Besides its role as an essential regulator of physiologic and pathologic angiogenesis, vascular endothelial growth factor (VEGF) triggers growth, survival, and migration of leukemia and multiple myeloma cells; plays a pivotal role in hematopoiesis; inhibits maturation of dendritic cells; and increases osteoclastic bone-resorbing activity as well as osteoclast chemotaxis. Dysregulation of VEGF expression and signaling pathways therefore plays an important role in the pathogenesis and clinical features of hematologic malignancies, in particular multiple myeloma. Direct and indirect targeting of VEGF and its receptors therefore may provide a potent novel therapeutic approach to overcome resistance to therapies and thereby improve patient outcome.

VEGF

VEGF isoforms. The original peptide growth factor vascular endothelial growth factor (VEGF), first described as vascular permeability factor (VPF) and now denoted VEGF-A, was identified in the 1980s.1-5  The heterozygous embryonic lethality induced by targeted inactivation of the VEGF gene,6,7  as well as the high homology of VEGF across species, reflects the pivotal importance of this protein.8,9  Beside the prototype member VEGF-A, there is now a VEGF family of structurally related dimeric glycoproteins belonging to the platelet-derived growth factor (PDGF) superfamily of growth factors. The VEGF family includes VEGF-B,10  VEGF-C,11  VEGF-D,12  VEGF-E, and placenta growth factor (PlGF).13,14  The active forms of VEGF are synthesized either as homodimers (40-45 kDa) or as heterodimers with other VEGF family members, such as PlGF. VEGF-A, located at chromosome 6p21.3, is encoded by 8 exons separated by 7 introns. Four principal isoforms of VEGF-A are generated by alternative splicing15,16 : VEGF121, the predominant isoform VEGF165, VEGF189, and VEGF206.4  These forms differ primarily in their bioavailability, which is conferred by heparin and heparan-sulfate binding domains encoded by exons 6 and 7. VEGF189 and VEGF206 contain additional stretches of basic residues, resulting in their nearly complete retention in the extracellular matrix (ECM). VEGF206 binds most strongly to heparin. VEGF165 lacks exon 6 and is secreted but also remains bound to the cell surface and the extracellular matrix via its heparin-binding sites. VEGF121, which lacks both exon 6 and exon 7, fails to bind heparin and is therefore a freely diffusible protein. The VEGF121, VEGF165, and VEGF189 forms are abundant and usually produced simultaneously. VEGF121 and VEGF165 isoforms induce mitogenic and permeability-enhancing activity on endothelial cells, whereas the other longer isoforms trigger only permeability-enhancing activity.15,17,18  Additionally, plasmin-induced cleavage of both VEGF165 and VEGF189 releases a bioactive carboxy-terminal domain111-165  of VEGF.19  Analysis of the crystal structure of VEGF-A shows an antiparallel homodimer, which is covalently linked by 2 disulfide bridges.20 

VEGF expression. VEGF165, VEGF189, and VEGF206 levels are increased in several human malignancies including breast,21  lung,22  brain,23  pancreatic,24  ovarian,25  kidney, and bladder carcinomas.26  Less frequently expressed are the VEGF-A splice forms VEGF145, VEGF183, VEGF162, and VEGF165b.27  VEGF145, for example, is expressed by cells derived from reproductive organs, the skin, and kidney28-31 ; it is also expressed by both human multiple myeloma (MM) cells32  and Kaposi sarcoma (KS)–associated herpesvirus or human herpesvirus-8 (KSHV or HHV-8)–associated primary effusion lymphomas (PELs).33 

Hypoxia is a key regulator of VEGF expression via the hypoxia-inducible factor-1 (HIF-1)/von Hippel-Lindau tumor suppressor gene (VHL) pathway,34,35  and VEGF is therefore most highly expressed adjacent to necrotic areas.36,37  Besides hypoxia, growth factors and cytokines including platelet-derived growth factor (PDGF), epidermal growth factor (EGF), fibroblast growth factor (FGF), tumor necrosis factor α (TNFα), tumor growth factor α and β1 (TNFα, TGFβ1), keratinocyte growth factor, insulin-like growth factor-1 (IGF-1), interleukin-1β (IL-1β), and IL-638  up-regulate transcription of VEGF mRNA.39,40  VEGF expression is also induced by UVB and H2O241 ; mutant p53 (via PKC)42  and mutant Ras oncogenes43,44 ; and proangiogenic oncogenes including Src, c-Myc, Fos, and Bcl-2.45 

VEGF receptors and signal transduction

VEGF receptors. VEGF-A, -B, -C, -D, and PlGF bind with different affinities to 3 related receptor tyrosine kinases: VEGF receptor-1 (VEGFR-1; fms-like tyrosine kinase-1; Flt-1), VEGFR-2 (kinase domain region, KDR; homolog to murine fetal liver kinase-1, Flk-1), and VEGFR-3. VEGF-A mediates its activity mainly via 2 receptor tyrosine kinases (RTKs): the high-affinity receptor VEGFR-1 (KD 10-20pM) located at chromosome 13q12-1346  and VEGFR-2 (KD 75-125pM) located at chromosome 4q11-1247-51  (Figure 1A). Both receptors have a crucial role in the development of the vascular system evidenced by embryonic lethality upon their disruption.52,53  These VEGF-RTKs are single-pass transmembrane receptors with 7 immunoglobulin-like loops in the extracellular domain and a cytoplasmic tyrosine-kinase domain, separated by an intervening, noncatalytic, 70-aa residue sequence. Both are modified after translation by N-linked glycosylation and phosphorylation on serine, threonine, and tyrosine. Using sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), VEGFR-1 migrates at a molecular mass of 180 kDa, and VEGFR-2 at 230 kDa. Hypoxia directly up-regulates VEGFR-1 gene expression via an HIF-1α binding site within the VEGFR-1 promoter. In contrast to VEGFR-1, VEGFR-2 lacks this binding site.54  The VEGF-A aa residues Arg82, Lys84, and His85 are required for binding to VEGFR-2, whereas the VEGF-A aa residues Asp63, Glu64, and Glu67 are required for binding to VEGFR-155  (Figure 1B).

Figure 1.

Interactions of VEGF family members with their receptors. (A) Growth factors and receptors of the VEGF family. Interactions of the VEGF family members VEGF-A, -B, -C, -D, -E, PlGF-1, PlGF-2 and the human immunodeficiency (HIV) Tat protein with the receptor tyrosine kinases VEGFR-1, VEGFR-2, and VEGFR-3; the accessory isoform specific receptors neuropilin-1 and -2 (NPR-1, -2); and heparansulfate proteoglycane (HSP) are shown. The receptors are displayed with their major structural motifs. VEGF-A splicing forms are in boxes. The extracellular domain of VEGFR-1 also is expressed as a soluble protein. (B) VEGFR-1 and -2. VEGF-A mediates its activity mainly via 2 receptor tyrosine kinases, VEGFR-1 and -2. VEGFR-1 and -2 are single-pass transmembrane receptors with 7 immunoglobulin (Ig)–like loops in the extracellular domain and a cytoplasmic tyrosine-kinase domain, separated by an intervening, noncatalytic, 70-aa residue sequence. Two VEGF monomers linked together by disulfide bonds induce receptor dimerization, thereby triggering kinase activation of both the receptor itself and several cytoplasmic signal transduction molecules.

Figure 1.

Interactions of VEGF family members with their receptors. (A) Growth factors and receptors of the VEGF family. Interactions of the VEGF family members VEGF-A, -B, -C, -D, -E, PlGF-1, PlGF-2 and the human immunodeficiency (HIV) Tat protein with the receptor tyrosine kinases VEGFR-1, VEGFR-2, and VEGFR-3; the accessory isoform specific receptors neuropilin-1 and -2 (NPR-1, -2); and heparansulfate proteoglycane (HSP) are shown. The receptors are displayed with their major structural motifs. VEGF-A splicing forms are in boxes. The extracellular domain of VEGFR-1 also is expressed as a soluble protein. (B) VEGFR-1 and -2. VEGF-A mediates its activity mainly via 2 receptor tyrosine kinases, VEGFR-1 and -2. VEGFR-1 and -2 are single-pass transmembrane receptors with 7 immunoglobulin (Ig)–like loops in the extracellular domain and a cytoplasmic tyrosine-kinase domain, separated by an intervening, noncatalytic, 70-aa residue sequence. Two VEGF monomers linked together by disulfide bonds induce receptor dimerization, thereby triggering kinase activation of both the receptor itself and several cytoplasmic signal transduction molecules.

Close modal

VEGFR-1 and VEGFR-2 are expressed in all adult vascular endothelial cells with the exception of vascular endothelial cells in the brain.56  Besides endothelial cells, VEGFR-1 is expressed on hematopoietic stem cells39  and monocytes57,58 ; human trophoblast, choriocarcinoma cells,59  renal mesangial cells,60  and vascular smooth muscle cells61 ; and MM and leukemic cells.62,63  VEGFR-2 also is expressed on circulating endothelial progenitor cells (CEPs),64-66  pancreatic duct cells,67  retinal progenitor cells,68  and megakaryocytes.69  Co-expression of VEGFR-1 and VEGFR-2 is found on normal human testicular tissue70  and in the myometrium. Significantly increased levels of both VEGFR-1 and -2 also are present on cancers of kidney, bladder,71  ovaries,25  and brain.23 

The role of VEGFR-2 in endothelial cells has been extensively studied: VEGFR-2 mediates developmental angiogenesis and hematopoiesis by triggering vascular endothelial cell proliferation, migration, differentiation, and survival, as well as by inducing vascular permeability and blood island formation.53  The functional role of VEGFR-1 is complex and dependent on both the developmental stage and cell type.72-74  Although the role of VEGFR-1 signaling cascades in endothelial cells is not fully delineated, VEGFR-1 signaling is required in hematopoiesis,75,76  monocyte migration,57,58,77  and paracrine release of growth factors.78,79  In addition, a recent report links VEGFR-1 signaling with production of MMP-9 in lung endothelial cells, thereby facilitating lung metastasis.80  Blockade of VEGFR-1 attenuates blood vessel formation in the setting of cancer, ischemic retinopathy, and rheumatoid arthritis; importantly, blocking VEGFR-1 abrogates inflammatory processes such as atherosclerosis and rheumatoid arthritis, whereas inhibiting VEGFR-2 does not.78 

VEGF-mediated signal transduction in endothelial cells. VEGF monomers linked by disulfide bonds induce receptor dimerization, thereby triggering kinase activation of both the receptor itself and several cytoplasmic signal transduction molecules including PLC-γ,81-84  VEGFR-associated protein (VRAP),85  Ras GTPase activating protein (Ras GAP),86  FAK,83,87,88  Sck,89,90  Src family of tyrosine kinases,91,92  Grb2,82,93  PI3-kinase/Akt,83,94-96  PKC,97-100  Raf-1,99,101  MEK/ERK,83,99,102-104  p38MAPK,88,105  Nck,86,94  Crk,82  Shc,93  and STAT.106  VEGFR kinase activity is additionally regulated by naturally occurring soluble forms of VEGFR-1 and -2; coreceptors including cadherins, integrin αvβ3, neuropilin-1 and -2107-110 ; polysaccharides heparin and heparan sulfate17,111 ; phosphatases SHP-1 and -293,94  and HCPTPA112 ; and small guanosine triphosphate (GTPase) RhoA.113 

VEGF functions

Angiogenesis and tumor progression. Blood vessels are required for tumor growth and progression for provision of vital oxygen and nutrients within the diffusion limit for oxygen (100-200 μm). Normally, primary embryonic vasculature is assembled from endothelial precursors (vasculogenesis) followed by angiogenesis, the expansion of this primitive network by sprouting, bridge-formation, and intussusception (insertion of interstitial tissue columns into the lumen of preexisting vessels). In addition to sprouting and co-option114  of neighboring preexisting vessels, tumor-derived angiogenic factors like VEGF promote formation of the endothelial lining of tumor vessels (vasculogenesis) by recruitment of highly proliferative circulating endothelial precursors (CEPs, angioblasts) from the bone marrow, hematopoietic stem cells (HSCs), progenitor cells, monocytes, and macrophages.115  In addition, tumor cells (ie, melanoma cells) can act as endothelial cells and form functional avascular blood conduits or mosaic blood vessels, which are lined partially by tumor cells and vessel walls.116-120 

CEPs, but not circulating endothelial cells sloughed from the vessel wall, are highly proliferative and contribute to tumor neoangiogenesis.115,121  HSCs and CEPs likely originate from a common precursor, the hemangioblast. Typically, CEPs express VEGFR-2, c-KIT, CD133, and CD146,64-66  whereas HSCs express VEGFR-1, Sca-1, and c-KIT; the lineage-specific differentiation of these HSCs into erythroid, myeloid, megakaryocytic, and lymphoid cells is dependent on the availability of specific cytokines including IL-3, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and thrombopoietin (TPO). Subsequently, hematopoietic progenitors and terminally differentiated precursor cells produce and secrete factors including VEGF, FGFs, brain-derived nerve growth-factor (BDNF), and angiopoietin; together with ECM proteins like fibronectin and collagen, these factors promote differentiation of CEPs, thereby contributing to new vessel formation. In addition, direct cellular contact with stromal cells also regulates the expansion of undifferentiated CEPs.115  Importantly, VEGFR-1–expressing hematopoietic cells and CEPs colocalize to cooperate in the formation of functional tumor vessels.122,123 

Angiogenesis is tightly regulated by proangiogenic and antiangiogenic molecules. In tumorigenesis, this balance is derailed,124  thereby triggering tumor growth, invasion, and metastasis.125,126  Pro- and antiangiogenic molecules arise from cancer cells, stromal cells, endothelial cells, the ECM, and blood.127  Importantly, the relative contribution of these molecules is dependent on the tumor type and site, and their expression changes with tumor growth, regression, and relapse. The “angiogenic switch”128  is triggered by oncogene-mediated tumor expression of angiogenic proteins including VEGF, FGF, PDGF, EGF, lysophosphatic acid (LPA), and angiopoetin, as well as by metabolic stress, mechanical stress, genetic mutations, and the immune response.124,125,129-133  The imbalance of angiogenic regulators (ie, VEGF and angiopoietin) accounts for an abnormal structure of tumor vessels, which in turn results in chaotic, variable blood flow and vessel leakiness, thereby lowering drug delivery and selecting more malignant tumor cells.134-137 

In the healthy adult, only 0.01% of endothelial cells undergo division,124  whereas up to 25% of endothelial cells divide in tumor vessels.138  Also, recent studies indicate that the gene expression pattern of normal endothelial cells differs from endothelial cells in tumors,139  for instance, 79 differentially expressed gene products were found in endothelial cells from colon cancer compared to normal endothelial cells.140  In addition, as tumor cells grow, a wider array of angiogenic molecules can be produced; therefore, if one proangiogenic molecule is blocked, tumors may use another molecule. A cocktail of antiangiogenic therapies may therefore be required to effectively prevent angiogenesis124  (Figure 2).

Figure 2.

The pathophysiologic functions of VEGF within the BM microenvironment. (A) Components of the bone marrow microenvironment and tumor angiogenesis. The BM microenvironment is a heterogeneous population of cells that are in tight association with the extracellular matrix (ECM) (fibronectin, laminin, collagen): immune cells (including NK cells, T lymphocytes, and monocytes) and dendritic cells (DCs); erythrocytes (Erys); hematopoietic stem cells (HSCs); progenitor and precursor cells; bone-marrow–derived circulating endothelial precursors (CEPs); endothelial cells (ECs); fibroblasts; osteoblasts and osteoclasts; and the tumor cells. Pro- and antiangiogenic molecules secreted by both the stromal and tumor cells contribute to tumor growth and progression. Tumor-derived angiogenic factors like VEGF promote tumor angiogenesis. Tumor vessels grow by co-option, sprouting, and intussusception, as well as by recruitment of CEPs and HSCs. Moreover, some tumor cells act as endothelial cells and form avascular conduits or mosaic blood vessels. (B) Additional biologic functions of VEGF. Besides angiogenesis, VEGF regulates hematopoiesis by mediating HSC survival and repopulation via both an autocrine loop and by inducing differentiation of multiple hematopoietic lineages. Moreover, VEGF inhibits maturation of DCs, increases bone-resorbing activity, modulates immune responses (eg, enhances NK cell adhesion to tumor endothelium), triggers CEP differentiation, and mediates monocyte and CEP recruitment to the vasculature. In the context of cancer, VEGF is an important growth, migration, and survival factor in Kaposi sarcoma, leukemia, and MM. These highly integrated processes involve paracrine, autocrine, and juxtacrine secretion of multiple growth factors, cytokines, and chemokines including IL-6, VEGF, IGF-1, and TNFα; and release of active metalloproteinases (MMPs, such as MMP9); as well as direct tumor–stromal cell and tumor cell–ECM contact.

Figure 2.

The pathophysiologic functions of VEGF within the BM microenvironment. (A) Components of the bone marrow microenvironment and tumor angiogenesis. The BM microenvironment is a heterogeneous population of cells that are in tight association with the extracellular matrix (ECM) (fibronectin, laminin, collagen): immune cells (including NK cells, T lymphocytes, and monocytes) and dendritic cells (DCs); erythrocytes (Erys); hematopoietic stem cells (HSCs); progenitor and precursor cells; bone-marrow–derived circulating endothelial precursors (CEPs); endothelial cells (ECs); fibroblasts; osteoblasts and osteoclasts; and the tumor cells. Pro- and antiangiogenic molecules secreted by both the stromal and tumor cells contribute to tumor growth and progression. Tumor-derived angiogenic factors like VEGF promote tumor angiogenesis. Tumor vessels grow by co-option, sprouting, and intussusception, as well as by recruitment of CEPs and HSCs. Moreover, some tumor cells act as endothelial cells and form avascular conduits or mosaic blood vessels. (B) Additional biologic functions of VEGF. Besides angiogenesis, VEGF regulates hematopoiesis by mediating HSC survival and repopulation via both an autocrine loop and by inducing differentiation of multiple hematopoietic lineages. Moreover, VEGF inhibits maturation of DCs, increases bone-resorbing activity, modulates immune responses (eg, enhances NK cell adhesion to tumor endothelium), triggers CEP differentiation, and mediates monocyte and CEP recruitment to the vasculature. In the context of cancer, VEGF is an important growth, migration, and survival factor in Kaposi sarcoma, leukemia, and MM. These highly integrated processes involve paracrine, autocrine, and juxtacrine secretion of multiple growth factors, cytokines, and chemokines including IL-6, VEGF, IGF-1, and TNFα; and release of active metalloproteinases (MMPs, such as MMP9); as well as direct tumor–stromal cell and tumor cell–ECM contact.

Close modal

Additional biologic functions of VEGF

Besides its role as an essential regulator of physiologic endothelial cell growth, permeability, and migration in vitro and in vivo,1-5,141,142  VEGF is a pivotal factor in hematopoiesis, which specifically affects the differentiation of multiple hematopoietic lineages.6,7,53,76  Importantly, VEGF mediates HSC survival and repopulation via an autocrine loop,76  whereas angiogenesis is regulated via a paracrine VEGF loop. In addition, VEGF inhibits maturation of dendritic cells through inhibition of nuclear factor κB activation143 ; increases both osteoclastic bone-resorbing activity144  and osteoclast chemotaxis145 ; induces migration, parathyroid hormone (PTH)–dependent cAMP accumulation, and alkaline phosphatase in osteoblasts146 ; enhances natural killer (NK) cell adhesion to tumor endothelium147 ; recruits monocyte57  and endothelial cell progenitors122  to the vasculature; stimulates surfactant production by alveolar type II cells148 ; and mediates a direct neuroprotective effect on motor neurons in vitro.149  In the context of cancer, VEGF is an important growth, migration, and survival factor in KS150-155 ; leukemia, and MM63,156  (Figure 2).

Angiogenesis and microvessel density (MVD) in MM and other hematologic malignancies

In solid tumors, VEGF has an important role in the induction of neovascularization, thereby promoting tumor growth and metastatic potential. However, it was not until 1993 that a role for VEGF and other angiogenic molecules also was defined in leukemias and other hematologic malignancies. First, VEGF was isolated from the HL-60 myeloid leukemia cell line,4  and bFGF was shown to be expressed by bone marrow (BM) stromal and peripheral blood cells.157  Later, increased vascularity was observed in the lymph nodes of B-cell non-Hodgkin lymphoma158  and B-cell chronic lymphocytic leukemia (B-CLL)159-161 ; as well as in BM specimens from patients with childhood acute lymphoid leukemia (ALL),162  acute myeloid leukemia (AML),163  chronic myelocytic leukemia (CML),164  myelodysplastic syndromes (MDS),165  and idiopathic myelofibrosis.166 

In MM, increased MVD in patient BM specimens correlates with disease progression and poor prognosis.167-171  Specifically, the extent of angiogenesis is directly correlated with the plasma-cell labeling index and inversely correlated with patient survival. The prognostic significance of angiogenesis in MM was further demonstrated by an Eastern Cooperative Oncology Group (ECOG) study of 75 newly diagnosed patients with MM. Overall survival was significantly longer in patients with low-grade (53 months) than with high-grade (24 months) or intermediate-grade (48 months) angiogenesis (P = .018).172  In addition, BM MVD at the time of initial diagnosis is an important prognostic factor for median overall survival and median progression-free survival in patients undergoing autologous transplantation as frontline therapy for MM. High-grade angiogenesis has similar prognostic impact in solitary bone plasmacytoma.173 

Although increased MVD in the BM is associated with initial tumor burden and relapse in MM, it may not be a good indicator of therapeutic response174,175  when tumor cytotoxicity exceeds the disappearance of capillaries. Therefore, a decrease in MVD during treatment indicates the effectiveness of the agent: for example, MVD decreases significantly in MM patients responding to thalidomide, but not in nonresponders.176  However, the absence of such a decrease in MVD does not necessarily indicate lack of response.177  As a substitute for MVD, potential surrogate markers include levels of VEGF or circulating BM-derived endothelial cells.178 

Importantly, a recent study of B-cell lymphomas found identical primary and secondary genetic aberrations simultaneously in endothelial cells and tumor cells, suggesting a close relationship between the genetic events in these 2 cell types. The authors suggest 4 different mechanisms that could explain this finding: (1) both cell types are derived from a common malignant precursor cell; (2) the endothelial cell carrying the genetic alteration of the lymphoma cell has arisen from a cell that was already committed to the lymphoid lineage; (3) lymphoma cell–endothelial cell fusion has occurred; or (4) apoptotic bodies from tumor cells have been taken up by endothelial cells.179 

In MM, endothelial cells of the BM (MMECs) represent a heterogeneous cell population forming tortuous, uneven vessels with profuse branching, and shunts.167  When compared to healthy quiescent human umbilical vein endothelial cells (HUVECs), MMECs demonstrate (1) enhanced expression of specific antigens including Tie2/Tek, CD105/endoglin, VEGFR-2, bFGFR-2, CD133 (AC133), aquaporin 1, and CD61 (β3 integrin); (2) enhanced capillarogenic activity; and (3) secretion of growth and invasive factors for plasma cells including bFGF, VEGF, MMP-2, and MMP-9. These findings therefore indicate that MMEC facilitates tumor cell growth, invasion, and dissemination; and conversely, raises the possibility of myeloma-induced endothelial-cell growth in the bone marrow.180  The frequency of myeloma-specific genetic aberrations in microvascular endothelial cells remains to be investigated.

VEGF and VEGF receptors in MM and other hematologic malignancies

VEGF and VEGF receptor expression was first reported in acute and chronic leukemias and myelodysplastic syndromes160,181-185  as well as in cell lines derived from hematopoietic malignancies including MM.159  Most studies found VEGFR-1 to be more commonly expressed than VEGFR-2. In MM, VEGFR-1 is widely expressed on both MM cell lines and patient MM cells, confirmed both by reverse-transcriptase polymerase chain reaction (RT-PCR) analyses and immunoprecipitation.32,159,186-188  The role for paracrine and juxtacrine VEGF-mediated tumor cell growth and survival is well established. In addition, co-expression of both VEGF and VEGF receptors in leukemia, lymphoma, and MM, coupled with its direct effects on tumor cell survival, migration, and proliferation, confirms the pivotal role for autocrine VEGF loops in the pathogenesis of these malignancies. Only recently have signaling pathways mediating these effects in hematologic malignancies been delineated.32,183,189-191 

Importantly VEGFR-1, but not VEGFR-2, is associated with inhibition of hematopoietic stem cell cycling, differentiation, and hematopoietic recovery in adults.76  The potential role of VEGF and VEGFR-1 in development of the MM cell clone in particular, and in leukemogenesis in general, remains to be investigated.

The functional role of VEGF in the pathogenesis of hematologic malignancies

VEGF and the tumor microenvironment. The BM microenvironment is a heterogeneous population of cells including hematopoietic stem cells; endothelial cells; stromal cells including fibroblasts, macrophages, T lymphocytes; and cells involved in bone homeostasis such as chondroclasts, osteoclasts, and osteoblasts (Figure 2). Differentiation, maintenance, and expansion of tumor cells, for example, MM cells, within the BM microenvironment is a highly coordinated process involving multiple growth factors, cytokines, and chemokines secreted by tumor cells (autocrine loop); stromal cells (paracrine loop); nonhematopoietic organs (eg, kidney and liver); and direct tumor cell–stromal cell contact (juxtacrine loop).

The function of VEGF and its receptors is one component of regulatory processes contributing to the pathogenesis of hematologic malignancies, including MM. VEGF is present in the BM microenvironment of patients with MM and associated with neovascularization at sites of MM cell infiltration.192  The secreted isoforms VEGF121, VEGF145, and VEGF165, as well as ECM- and surface-bound VEGF189 and VEGF206, are produced by MM cell lines, as well as by patient MM and plasma cell leukemia (PCL) cells.32 

“Public” (or “external”) autocrine loops, where growth factors (eg, VEGF) are secreted by tumor cells and then activate receptors on both tumor cells and other cells, have been described in several hematologic malignancies, including MM. “Private” (or “internal”) autocrine loops, where the factor activates autonomous cell growth via an intracellular receptor without being secreted,193  have been described in AML cells and in murine experimental models (eg, for IL-3, GM-CSF, v-sis/c-sis/PDGF). In contrast to the “public” autocrine loop, cell proliferation mediated by a “private” VEGF autocrine loop is not cell-density dependent, and neutralizing antibodies do not prevent continued cell growth or differentiation.193-199  Importantly, this independence of factor secretion contrasts the regulatory role of VEGF during hematopoiesis versus angiogenesis.

Extracellular matrix (ECM) proteins laminin, microfibrillar collagen type VI, and fibronectin are strong adhesive components for tumor cells, and their adhesion to laminin and fibronectin is β1-integrin (CD29) mediated.200  β1-integrins expressed on MM cells, specifically α-integrins VLA-4 (α4β1) and VLA-5 (α5β1)201,202  mediate adhesion to endothelial cells and bone marrow stromal cells (BMSCs), thereby conferring protection against drug-induced apoptosis both by cell-cell contact and by triggering NFκB-dependent transcription and secretion of IL-6, a major MM growth, survival, and drug resistance factor.203,204  Importantly, IL-6 secreted by BMSCs enhances the production and secretion of VEGF by MM cells, thereby augmenting MM cell growth and survival159,186,205 ; conversely, binding of MM cells to BMSCs enhances IL-6, IGF-1, and VEGF secretion in BMSCs.186,206,207  Specifically, IGF-1 induces HIF-1α, which triggers VEGF expression208 ; consequently, inhibition of IGFR-1 activity markedly decreases VEGF secretion in MM/BMSC cocultures.206  Other mechanisms regulating VEGF expression in MM cells include c-maf and CD40. c-maf–driven expression of integrin β7 enhances adhesion to BM stroma and thereby increases VEGF production,209  and CD40 activation induces p53-dependent VEGF secretion.210 

In CML, VEGF is expressed at high levels in the bone marrow and the peripheral blood; moreover, the CML-associated oncogene Bcr-Abl induces VEGF- and HIF1α-gene expression via a PI3K-mTOR–dependent pathway211  (Figure 3).

Figure 3.

Regulation of VEGF expression. VEGF-A levels are increased in several hematologic malignancies, including MM. Factors modulating VEGF secretion include (A) secretion of IL-6 or VEGF by both BMSCs and tumor cells (paracrine/autocrine loop); (B) hypoxia and the presence of mutant oncogenes (ie, mutant Ras [mutRas] or Bcr-Abl, which up-regulate VEGF expression via HIF-1α protein); (C) secretion of IGF-1, which up-regulates VEGF production and secretion in tumor cells (paracrine loop); (D) c-maf–driven expression of tumor integrin β7; (E) tumor cell expression of ICAM1 and LFA1 modulating adhesion to ECM and BMSCs, thereby increasing VEGF production and secretion; and (F) CD40 activation, which induces p53-dependent VEGF secretion. Furthermore, VEGFR-1 expression is regulated, for instance, by IGF-1 via HIF-1α (C).

Figure 3.

Regulation of VEGF expression. VEGF-A levels are increased in several hematologic malignancies, including MM. Factors modulating VEGF secretion include (A) secretion of IL-6 or VEGF by both BMSCs and tumor cells (paracrine/autocrine loop); (B) hypoxia and the presence of mutant oncogenes (ie, mutant Ras [mutRas] or Bcr-Abl, which up-regulate VEGF expression via HIF-1α protein); (C) secretion of IGF-1, which up-regulates VEGF production and secretion in tumor cells (paracrine loop); (D) c-maf–driven expression of tumor integrin β7; (E) tumor cell expression of ICAM1 and LFA1 modulating adhesion to ECM and BMSCs, thereby increasing VEGF production and secretion; and (F) CD40 activation, which induces p53-dependent VEGF secretion. Furthermore, VEGFR-1 expression is regulated, for instance, by IGF-1 via HIF-1α (C).

Close modal

What is the functional role of VEGF in tumorigenesis of hematologic malignancies in general, and of MM in particular? In addition to stimulating angiogenesis, our studies show that VEGF directly stimulates MM cell migration on fibronectin, proliferation, and survival via autocrine and paracrine loops. Importantly, the range of VEGF target cells within the BM compartment of MM may be even broader since VEGF dramatically affects the differentiation of multiple hematopoietic lineages in vivo; increases the production of B cells and generation of myeloid cells143,212 ; (3) regulates HSC survival by an internal autocrine loop mechanism76 ; increases both osteoclastic bone-resorbing activity144  and osteoclast chemotaxis145 ; and inhibits maturation of dendritic cells.143  For example, we have shown that addition of anti-VEGF antibodies to MM patients' BM sera abrogates its inhibitory effect on dendritic cell maturation.213  Therefore, besides angiogenesis, dysregulation of VEGF plays an important role in MM pathogenesis and clinical features, including lytic lesions of the bone and immune deficiency. Inhibition of VEGF in MM may therefore target not only endothelial cells and MM cells, but also a broad array of cells contributing to MM pathogenesis.

VEGF signal transduction. In MM, tumor cell growth, survival, and migration are necessary for homing of MM cells to the BM, their expansion within the BM microenvironment, and their egress into the peripheral blood. Binding of exogenous VEGF165 to MM cells triggers VEGFR-1 tyrosine phosphorylation. Subsequently, several downstream signaling pathways are activated: (1) a PI3-kinase/protein kinase Cα (PKCα)–dependent cascade mediating MM cell migration on fibronectin, evidenced by using the PKC inhibitor bisindolylmaleimide I and LY294002; (2) a MEK-extracellular signal-regulated protein kinase (ERK) pathway mediating MM cell proliferation, evidenced by use of anti-VEGF antibody and PD09805932 ; and (3) a pathway mediating MM cell survival via up-regulation of Mcl-1 and survivin in a dose- and time-dependent manner214  (Figure 4).

Figure 4.

VEGF signal transduction in MM cells. VEGF mediates MM cell proliferation via MEK-1/ERK signaling and MM cell survival via up-regulation of survivin and Mcl-1. VEGF-induced MM cell migration on fibronectin is dependent on the localization of VEGFR-1 within caveolae, followed by Src tyrosine kinase family–dependent phosphorylation of caveolin-1, PI3-kinase, and PKCα.

Figure 4.

VEGF signal transduction in MM cells. VEGF mediates MM cell proliferation via MEK-1/ERK signaling and MM cell survival via up-regulation of survivin and Mcl-1. VEGF-induced MM cell migration on fibronectin is dependent on the localization of VEGFR-1 within caveolae, followed by Src tyrosine kinase family–dependent phosphorylation of caveolin-1, PI3-kinase, and PKCα.

Close modal

As in MM, autocrine VEGF stimulation of VEGFR-2 triggers leukemic cell proliferation and migration, thereby inducing a more invasive tumor phenotype.183  Moreover, VEGF induces the expression of heat shock protein 90 (Hsp90) and its binding to Bcl-2 and Apaf-1, thereby increasing leukemic cell resistance to serum deprivation-induced apoptosis.190 

In addition to the known paracrine/external autocrine/juxtacrine loops, an internal autocrine loop of VEGF similar to AML may contribute to growth factor and cell density–independent proliferation of MM cells. Internalization and functional intracellular trafficking of VEGFR-1 may be mediated by lipid rafts in general and caveolae in particular. Functionally, caveolae, vesicular flask-shaped invaginations of the plasma membrane, which are composed of caveolins, cholesterol, and sphingolipids, have been implicated in transmembrane transport and signal transduction.215,216  Specifically, we recently demonstrated that caveolae and caveolin-1 are present in MM cells and are required for IL-6- and IGF-1–triggered Akt-1–mediated survival of MM cells.217  Ongoing studies are exploring whether caveolae mediate VEGFR-1 trafficking in MM cells, thereby mediating both “private” and “public” autocrine MM cell proliferation and survival; as well as development of the tumor cell clone.

Therapeutic approaches to target VEGF

Several direct and indirect VEGF and VEGF receptor inhibitor strategies are under clinical investigation for treatment of solid tumors and hematologic malignancies (http://www.cancer.gov/clinicaltrials/developments/anti-angio-table). Approaches to disrupt the VEGF/VEGF receptor signaling pathways range from small molecule ATP competitive VEGF receptor inhibitors to biologic agents like soluble receptors, anti-VEGF and anti-VEGF receptor antibodies, small molecule inhibitors, and VEGF transcription inhibitors. The earliest study showing that VEGF blockade by a monoclonal antibody suppressed angiogenesis and tumor growth in vivo was in a glioblastoma cell line.218  The antitumor effect of VEGF inactivation in vivo was more recently shown in a murine insulinoma model.219 

Anti-VEGF antibody (bevacizumab; Avastin). The most successful approach to date to therapeutically target VEGF is the use of a humanized monoclonal antibody against VEGF, bevacizumab (Avastin),220  which was United States Food and Drug Administration (USFDA) approved for use as a first-line therapy for metastatic colorectal cancer in February 2004; specifically, bevacizumab in combination with intravenous 5-FU–based chemotherapy is a new treatment option.221  Furthermore, bevacizumab also significantly prolonged time to progression of disease in patients with metastatic renal-cell cancer in a clinical phase 2 trial.222,223  Effects of bevacizumab also were seen in combination with chemotherapy in non–small-cell lung cancer (NSCLC),224,225  pancreatic226  and breast carcinoma227 ; with interferon-α in both melanoma and metastatic renal cell carcinoma228 ; with radiotherapy in rectal cancer; and with thalidomide in metastatic renal-cell carcinoma. Interestingly, bevacicumab reduces the number of CEPs and increases the fraction of tumor endothelial cells with pericyte coverage, thereby reflecting the dropout of immature endothelial cells and potentially providing a novel biomarker.229  Ongoing studies in hematologic malignancies are evaluating the efficacy of bevacizumab in patients with relapsed or refractory MM (with or without thalidomide), blastic phase chronic myelogenous leukemia (CML-BP), myelodysplastic syndrome (MDS), and relapsed aggressive non-Hodgkin lymphoma (NHL).

VEGF-trap. Another approach is to target the VEGFR. Flt1-3  IgG, a Fc fusion with the first 3 Ig-like domains of VEGFR-1, inhibits tumor growth in a murine rhabdomyosarcoma xenograft model.230  A hybrid Fc construct in which domain 2 of VEGFR-1 is joined to domain 3 of the VEGFR-2 (VEGF-trap)231  causes regression of co-opted vessels in a model of neuroblastoma.232  Importantly, ongoing clinical studies are evaluating the efficacy of the VEGF trap in patients with incurable relapsed or refractory solid tumors or NHL.

PTK787/ZK222584. PTK787/ZK222584 is an orally available tyrosine kinase inhibitor (Novartis Pharmaceuticals) that binds to the ATP-binding sites of VEGF receptors.233,234  In MM, we have reported that PTK787/ZK222584 acts directly on MM cells to inhibit VEGF-induced MM cell growth and migration and inhibits paracrine IL-6–mediated MM cell growth in the BM milieu.188  PTK787/ZK222584 is now under evaluation in a phase 3 trial for colorectal cancer; a phase 1 trial together with imatinib mesylate (Gleevec) for AML, AMM, CML-BP; a phase 2 trial for primary or secondary MDS; and a phase 1 trial for MM.

Indazolylpyrimidine pan-VEGFR inhibitors. The indazolylpyrimidine GW654652 is a small molecule tyrosine kinase inhibitor that inhibits all 3 VEGF receptors with similar potency. Preclinical data demonstrates that GW654652 is a potent inhibitor of both VEGF- and bFGF-mediated angiogenesis, as well as VEGF-induced vascular permeability in vivo. In addition, daily oral dosing with GW654652 inhibits the growth of human tumor head, neck, colon, melanoma, and prostate cancer xenografts in vivo.235  Moreover, GW654652 has a favorable pharmacokinetic profile in murine and canine studies, suggesting its potential clinical application.236  In MM, the indazolylpyrimidine class of pan-VEGF receptor inhibitors acts both directly on tumor cells and in the BM microenvironment to overcome drug resistance. Specifically, GW654652 inhibits VEGF-triggered migrational activity and proliferation of MM cell lines, including those sensitive and resistant to conventional therapy, in a dose-dependent fashion. Furthermore, GW654652 blocks both VEGF-induced VEGFR-1 phosphorylation and downstream activation of AKT-1 and MAPK signaling pathways. Importantly, GW654652 also acts in the BM microenvironment, since it blocks HUVEC proliferation and inhibits both IL-6 and VEGF secretion, as well as proliferation of MM cells induced by MM cell binding to BM stromal cells. Importantly, inhibition of MM cell growth, survival, and migration is not reversed by removal of GW654652 after treatment; in contrast, its effects on HUVEC survival and proliferation are partially reversible after drug removal. The higher sensitivity of MM cells may be due to lower VEGF receptor expression levels in MM cells than in HUVECs. Alternatively, these data may indicate that long-term exposure of MM cells to GW654652 leads to stable destruction of VEGFR-1 on MM cells. These results therefore suggest potential use of this drug class to target both tumor cells and their microenvironment.237  A phase 1 clinical trial in MM is planned at our institution.

Other VEGF inhibitors. Significant efficacy of RTK inhibitors including molecule SU5416 (Sugen),238-240  SU11248 (Sugen),241  AG013676 and CP-547632 (Pfizer),242  ZD6474 (AstraZeneca),243  and BAY 43-9006 (Bayer/Onyx)244,245  has been demonstrated in both preclinical models and clinical trials of solid tumors and hematologic malignancies including AML, MDS, and MM.

Therapeutic approaches directly targeting endothelial cells

Thalidomide/IMiDs. Based upon its antiangiogenic activity,246  Thal was used empirically to treat patients with refractory relapsed MM and achieved responses in one third of cases.174  Subsequently, a series of immunomodulatory drugs (IMiDs) has been developed.247  Importantly, both Thal and the more potent IMiDs can overcome the growth and survival advantage conferred by the BM milieu, including down-regulating VEGF.248,249  Proliferation and capillarogenesis of MMECs also are significantly inhibited by thalidomide.180  Moreover the IMiDs costimulate T cells, enhance antitumor immunity mediated by IFNγ and IL-2, and augment NK cell cytotoxicity.250  These studies provided the basis for the use of IMiD CC-5013 (Revimid, now REVLIMID) (Celgene) in a phase 1 dose-escalation trial in patients with relapsed and refractory MM, which demonstrated either response or stabilization of disease in 79% cases.251  Two clinical phase 2 trials have confirmed these data, achieving complete responses with favorable side effect profiles, and 2 clinical phase 3 trials comparing Revlimid to dexamethasone/Revlimid treatment of relapsed MM are now completely enrolled.

A phase 1/2 study in patients with advanced MM using IMiD CC-4047 (Actimid) (Celgene) showed antimyeloma activity and an acceptable safety profile.252  In addition to MM, clinical studies are ongoing in MDS, large B-cell lymphoma, CLL, and small lymphocytic lymphomas.247 

2-ME-2. 2-Methoxyestradiol (2-ME-2), a natural metabolite of estradiol, is a potent antitumor and antiangiogenic agent in leukemic cells.253-258  However, the mechanisms mediating its biologic effects remain unclear. Our recent studies show that 2ME2 also inhibits growth and induces apoptosis in MM cell lines and patient cells. Importantly, VEGF secretion induced by adhesion of MM cells to BMSCs is inhibited by 2ME2. Conversely, 2ME2 inhibits MM cell growth, prolongs survival, and decreases angiogenesis in a murine model.259  Clinical phase 1 studies are under way in both solid tumors and in MM.

LY317615 (PKCβ inhibitor). Preclinical data show that the PKCβ inhibitor LY317615 decreases plasma VEGF levels in human tumor xenograft-bearing mice.260-262  A clinical phase 2 trial is now active, which tests the efficacy of LY 317615 in patients with relapsed or refractory lymphoma (Table 1).

Therapeutic approach inhibiting endothelial-specific integrin/survival signaling

The cyclic pentapeptide EMD 121974 (cilengitide) mediates its antiangiogenic activity via selective inhibition of integrins ανβ3 and ανβ5.263-266  Clinical trials are ongoing in AML and lymhomas.

Additional approaches directly or indirectly targeting VEGF

Lysophosphatidic acid acyltransferase-β (LPAAT) inhibitors. Lysophosphatidic acid (LPA), an intracellular lipid mediator with growth factor–like activities, stimulates a specific G protein–coupled receptor present in numerous cell types, thereby triggering a multitude of biologic responses.267  LPA stimulates VEGF expression and secretion in ovarian cancer cells, thereby increasing tumor angiogenesis and subsequent tumor growth and metastasis.268  Conversely, we have recently demonstrated that LPA acyltransferase (LPAAT) inhibitors (Cell Therapeutics, Seattle, WA) have antitumor activity in MM, at least in part due to their inhibitory effect on VEGF expression.269 

Bortezomib. Bortezomib (previously denoted PS341) is a novel proteasome inhibitor recently approved by the USFDA for therapy of patients with progressive MM after previous treatment.270  It induces apoptosis in drug-resistant MM cells and inhibits binding of MM cells in the BM microenvironment, as well as production and secretion of cytokines that mediate MM cell growth and survival. IL-6–triggered phosphorylation of ERK, but not of STAT3, is blocked by bortezomib.271  Moreover, bortezomib mediates anti-MM activity by triggering phosphorylation of both p53 protein and JNK, cleavage of DNA-PKcs and ATM,272  and caspase-dependent down-regulation of gp130.273  The antiangiogenic effect of bortezomib274,275  is another potential mechanism of its anti-MM activity.276  Moreover, our recent studies show that bortezomib down-regulates caveolin-1 expression and inhibits caveolin-1 tyrosine phosphorylation, which are required for VEGF-mediated MM cell migration on fibronectin; and blocks VEGF-induced tyrosine phosphorylation of caveolin-1 in HUVECs, thereby inhibiting ERK-dependent endothelial cell proliferation.

CD40 antibody. CD40 activation induces p53-dependent VEGF secretion210 ; conversely, a humanized anti-CD40 antibody induces cytotoxicity in human MM cells.277  A clinical trial is ongoing at our institution.

Combination therapy/metronomic chemotherapy

The production of pro- and antiapoptotic molecules changes during the course of conventional therapy for cancer. Specifically, prior studies show that surgery and chemotherapy, in contrast to irradiation, may even enhance tumor angiogenesis by stimulating production of VEGF and other endothelial-cell survival and growth factors in tumor cells.278  High local VEGF concentrations in the BM microenvironment of MM patients suppress the antiproliferative effects of several chemotherapeutics, thereby promoting multidrug resistance.279,280  Therefore, combining chemotherapies and irradiation with drugs that block VEGF signaling may enhance antitumor efficacy, for example, by “normalizing” tumor vasculature and thereby improving oxygenation and delivery of chemotherapies to tumor cells.281  Enhanced antitumor activity of conventional chemotherapy282-284  and irradiation285,286  regimens has been achieved when combined with antiangiogenic drugs. Novel therapeutic strategies of metronomic chemotherapy287,288  use frequent uninterrupted administration of conventional chemotherapeutics in doses significantly below the maximum tolerated dose (MTD) for prolonged periods,289  thereby both reducing toxic side effects and improving antitumor effects.290-292  Another advantage of metronomic chemotherapy is the possibility that it may be combined with antiangiogenic drugs like bevacizumab (Avastin).221 

Conclusions and future therapeutic perspectives

The complexity of VEGF actions is determined by a multitude of target cells. Besides its role as an essential regulator of physiologic and pathologic angiogenesis, VEGF is now known to trigger growth, survival, and migration of leukemia and MM cells via paracrine and autocrine pathways; to inhibit maturation of dendritic cells and to increase bone-resorbing activity. Moreover, VEGF also is associated with HSC differentiation and hematopoietic recovery in adults. VEGF levels and increased vascularity are correlated with clinical outcome in hematologic malignancies including leukemias, lymphomas, and MM. In addition, effects of VEGF on target cells other than endothelial cells may contribute to the clinical manifestations of leukemias, lymphomas, and MM. Direct and indirect targeting of VEGF and its receptors are therefore promising novel therapeutic approaches to improve patient outcome.

When tumor cells grow, a wide array of angiogenic molecules may be produced. This at least in part, may be the reason why single-agent therapy inhibiting VEGF is only effective initially and that a cocktail of antiangiogenic therapies is required to effectively prevent tumor angiogenesis. Enhancement of antitumor efficacy can also be achieved by combining drugs that block VEGF signaling with chemotherapies or irradiation, thereby “normalizing” and sensitizing tumor vasculature and improving oxygenation and delivery of chemotherapies to tumor cells and endothelial cells. In addition, VEGF actions and the array of its target cells may vary, depending on the stage of the malignancy and the tumor type. Ongoing studies are addressing these dynamic interactions and translating them into therapeutic strategies. Furthermore, since VEGF plays a pivotal role in HSC differentiation, the potential role of VEGF and VEGFR-1 in clonal leukemogenic development also is under investigation. A close collaboration between basic researchers and clinicians will be required to both enhance our understanding of the pathophysiologic role of VEGF in hematologic malignancies and derive related targeted clinical trials to eventually improve patient outcome.

Prepublished online as Blood First Edition Paper, October 7, 2004; DOI 10.1182/blood-2004-07-2909.

Supported by a Multiple Myeloma Research Foundation (MMRF) Senior Research Grant Award (K.P.); National Institutes of Health Grants IP50 CA100707, PO-1 78378, and RO-1 CA 50945; and the Doris Duke Distinguished Clinical Research Scientist Award (K.C.A.).

The authors thank all members of the Jerome Lipper Multiple Myeloma Center for helpful discussions.

1
Senger DR, Galli SJ, Dvorak AM, Perruzzi CA, Harvey VS, Dvorak HF. Tumor cells secrete a vascular permeability factor that promotes accumulation of ascites fluid.
Science
.
1983
;
219
:
983
-985.
2
Ferrara N, Henzel WJ. Pituitary follicular cells secrete a novel heparin-binding growth factor specific for vascular endothelial cells.
Biochem Biophys Res Commun
.
1989
;
161
:
851
-858.
3
Connolly DT, Olander JV, Heuvelman D, et al. Human vascular permeability factor: isolation from U937 cells.
J Biol Chem
.
1989
;
264
:
20017
-20024.
4
Leung DW, Cachianes G, Kuang WJ, Goeddel DV, Ferrara N. Vascular endothelial growth factor is a secreted angiogenic mitogen.
Science
.
1989
;
246
:
1306
-1309.
5
Keck PJ, Hauser SD, Krivi G, et al. Vascular permeability factor, an endothelial cell mitogen related to PDGF.
Science
.
1989
;
246
:
1309
-1312.
6
Ferrara N, Carver-Moore K, Chen H, et al. Heterozygous embryonic lethality induced by targeted inactivation of the VEGF gene.
Nature
.
1996
;
380
:
439
-442.
7
Carmeliet P, Ferreira V, Breier G, et al. Abnormal blood vessel development and lethality in embryos lacking a single VEGF allele.
Nature
.
1996
;
380
:
435
-439.
8
Conn G, Bayne ML, Soderman DD, et al. Amino acid and cDNA sequences of a vascular endothelial cell mitogen that is homologous to platelet-derived growth factor.
Proc Natl Acad Sci U S A
.
1990
;
87
:
2628
-2632.
9
Senger DR, Connolly DT, Van de Water L, Feder J, Dvorak HF. Purification and NH2-terminal amino acid sequence of guinea pig tumor-secreted vascular permeability factor.
Cancer Res
.
1990
;
50
:
1774
-1778.
10
Olofsson B, Pajusola K, Kaipainen A, et al. Vascular endothelial growth factor B, a novel growth factor for endothelial cells.
Proc Natl Acad Sci U S A
.
1996
;
93
:
2576
-2581.
11
Joukov V, Pajusola K, Kaipainen A, et al. A novel vascular endothelial growth factor, VEGF-C, is a ligand for the Flt4 (VEGFR-3) and KDR (VEGFR-2) receptor tyrosine kinases.
EMBO J
.
1996
;
15
:
1751
.
12
Achen MG, Jeltsch M, Kukk E, et al. Vascular endothelial growth factor D (VEGF-D) is a ligand for the tyrosine kinases VEGF receptor 2 (Flk1) and VEGF receptor 3 (Flt4).
Proc Natl Acad Sci U S A
.
1998
;
95
:
548
-553.
13
Maglione D, Guerriero V, Viglietto G, Delli-Bovi P, Persico MG. Isolation of a human placenta cDNA coding for a protein related to the vascular permeability factor.
Proc Natl Acad Sci U S A
.
1991
;
88
:
9267
-9271.
14
Maglione D, Guerriero V, Viglietto G, et al. Two alternative mRNAs coding for the angiogenic factor, placenta growth factor (PlGF), are transcribed from a single gene of chromosome 14.
Oncogene
.
1993
;
8
:
925
-931.
15
Houck KA, Ferrara N, Winer J, Cachianes G, Li B, Leung DW. The vascular endothelial growth factor family: identification of a fourth molecular species and characterization of alternative splicing of RNA.
Mol Endocrinol
.
1991
;
5
:
1806
-1814.
16
Tischer E, Mitchell R, Hartman T, et al. The human gene for vascular endothelial growth factor: multiple protein forms are encoded through alternative exon splicing.
J Biol Chem
.
1991
;
266
:
11947
-11954.
17
Houck KA, Leung DW, Rowland AM, Winer J, Ferrara N. Dual regulation of vascular endothelial growth factor bioavailability by genetic and proteolytic mechanisms.
J Biol Chem
.
1992
;
267
:
26031
-26037.
18
Park JE, Keller GA, Ferrara N. The vascular endothelial growth factor (VEGF) isoforms: differential deposition into the subepithelial extracellular matrix and bioactivity of extracellular matrix-bound VEGF.
Mol Biol Cell
.
1993
;
4
:
1317
-1326.
19
Keyt BA, Berleau LT, Nguyen HV, et al. The carboxyl-terminal domain (111-165) of vascular endothelial growth factor is critical for its mitogenic potency.
J Biol Chem
.
1996
;
271
:
7788
-7795.
20
Muller YA, Li B, Christinger HW, Wells JA, Cunningham BC, de Vos AM. Vascular endothelial growth factor: crystal structure and functional mapping of the kinase domain receptor binding site.
Proc Natl Acad Sci U S A
.
1997
;
94
:
7192
-7197.
21
Yoshiji H, Gomez DE, Shibuya M, Thorgeirsson UP. Expression of vascular endothelial growth factor, its receptor, and other angiogenic factors in human breast cancer.
Cancer Res
.
1996
;
56
:
2013
-2016.
22
Volm M, Koomagi R, Mattern J. Prognostic value of vascular endothelial growth factor and its receptor Flt-1 in squamous cell lung cancer.
Int J Cancer
.
1997
;
74
:
64
-68.
23
Hatva E, Kaipainen A, Mentula P, et al. Expression of endothelial cell-specific receptor tyrosine kinases and growth factors in human brain tumors.
Am J Pathol
.
1995
;
146
:
368
-378.
24
Ellis LM, Takahashi Y, Fenoglio CJ, Cleary KR, Bucana CD, Evans DB. Vessel counts and vascular endothelial growth factor expression in pancreatic adenocarcinoma.
Eur J Cancer
.
1998
;
34
:
337
-340.
25
Boocock CA, Charnock-Jones DS, Sharkey AM, et al. Expression of vascular endothelial growth factor and its receptors flt and KDR in ovarian carcinoma.
J Natl Cancer Inst
.
1995
;
87
:
506
-516.
26
Brown LF, Berse B, Jackman RW, et al. Increased expression of vascular permeability factor (vascular endothelial growth factor) and its receptors in kidney and bladder carcinomas.
Am J Pathol
.
1993
;
143
:
1255
-1262.
27
Ferrara N, Gerber HP, LeCouter J. The biology of VEGF and its receptors.
Nat Med
.
2003
;
9
:
669
-676.
28
Poltorak Z, Cohen T, Sivan R, et al. VEGF145, a secreted vascular endothelial growth factor isoform that binds to extracellular matrix.
J Biol Chem
.
1997
;
272
:
7151
-7158.
29
Burchardt T, Burchardt M, Chen MW, et al. Expression of VEGF splice variants 144/145 and 205/206 in adult male tissues.
IUBMB Life
.
1999
;
48
:
405
-408.
30
Tober KL, Cannon RE, Spalding JW, et al. Comparative expression of novel vascular endothelial growth factor/vascular permeability factor transcripts in skin, papillomas, and carcinomas of v-Ha-ras Tg. AC transgenic mice and FVB/N mice.
Biochem Biophys Res Commun
.
1998
;
247
:
644
-653.
31
Whittle C, Gillespie K, Harrison R, Mathieson PW, Harper SJ. Heterogeneous vascular endothelial growth factor (VEGF) isoform mRNA and receptor mRNA expression in human glomeruli, and the identification of VEGF148 mRNA, a novel truncated splice variant.
Clin Sci (Lond)
.
1999
;
97
:
303
-312.
32
Podar K, Tai YT, Davies FE, et al. Vascular endothelial growth factor triggers signaling cascades mediating multiple myeloma cell growth and migration.
Blood
.
2001
;
98
:
428
-435.
33
Aoki Y, Tosato G. Vascular endothelial growth factor/vascular permeability factor in the pathogenesis of primary effusion lymphomas.
Leuk Lymphoma
.
2001
;
41
:
229
-237.
34
Wang GL, Semenza GL. Purification and characterization of hypoxia-inducible factor 1.
J Biol Chem
.
1995
;
270
:
1230
-1237.
35
Iliopoulos O, Levy AP, Jiang C, Kaelin WG Jr, Goldberg MA. Negative regulation of hypoxia-inducible genes by the von Hippel-Lindau protein.
Proc Natl Acad Sci U S A
.
1996
;
93
:
10595
-10599.
36
Shweiki D, Itin A, Soffer D, Keshet E. Vascular endothelial growth factor induced by hypoxia may mediate hypoxia-initiated angiogenesis.
Nature
.
1992
;
359
:
843
-845.
37
Plate KH, Breier G, Weich HA, Risau W. Vascular endothelial growth factor is a potential tumour angiogenesis factor in human gliomas in vivo.
Nature
.
1992
;
359
:
845
-848.
38
Cohen T, Nahari D, Cerem LW, Neufeld G, Levi BZ. Interleukin 6 induces the expression of vascular endothelial growth factor.
J Biol Chem
.
1996
;
271
:
736
-741.
39
Ferrara N, Davis-Smyth T. The biology of vascular endothelial growth factor.
Endocr Rev
.
1997
;
18
:
4
-25.
40
Neufeld G, Cohen T, Gengrinovitch S, Poltorak Z. Vascular endothelial growth factor (VEGF) and its receptors.
FASEB J
.
1999
;
13
:
9
-22.
41
Brauchle M, Funk JO, Kind P, Werner S. Ultraviolet B and H2O2 are potent inducers of vascular endothelial growth factor expression in cultured keratinocytes.
J Biol Chem
.
1996
;
271
:
21793
-21797.
42
Kieser A, Weich HA, Brandner G, Marme D, Kolch W. Mutant p53 potentiates protein kinase C induction of vascular endothelial growth factor expression.
Oncogene
.
1994
;
9
:
963
-969.
43
Rak J, Mitsuhashi Y, Bayko L, et al. Mutant ras oncogenes upregulate VEGF/VPF expression: implications for induction and inhibition of tumor angiogenesis.
Cancer Res
.
1995
;
55
:
4575
-4580.
44
Grugel S, Finkenzeller G, Weindel K, Barleon B, Marme D. Both v-Ha-Ras and v-Raf stimulate expression of the vascular endothelial growth factor in NIH 3T3 cells.
J Biol Chem
.
1995
;
270
:
25915
-25919.
45
Kerbel R, Folkman J. Clinical translation of angiogenesis inhibitors.
Nat Rev Cancer
.
2002
;
2
:
727
-739.
46
Satoh H, Yoshida MC, Matsushime H, Shibuya M, Sasaki M. Regional localization of the human c-ros-1 on 6q22 and flt on 13q12.
Jpn J Cancer Res
.
1987
;
78
:
772
-775.
47
de Vries C, Escobedo JA, Ueno H, Houck K, Ferrara N, Williams LT. The fms-like tyrosine kinase, a receptor for vascular endothelial growth factor.
Science
.
1992
;
255
:
989
-991.
48
Shibuya M, Yamaguchi S, Yamane A, et al. Nucleotide sequence and expression of a novel human receptor-type tyrosine kinase gene (flt) closely related to the fms family.
Oncogene
.
1990
;
5
:
519
-524.
49
Terman BI, Dougher-Vermazen M, Carrion ME, et al. Identification of the KDR tyrosine kinase as a receptor for vascular endothelial cell growth factor.
Biochem Biophys Res Commun
.
1992
;
187
:
1579
-1586.
50
Quinn TP, Peters KG, De Vries C, Ferrara N, Williams LT. Fetal liver kinase 1 is a receptor for vascular endothelial growth factor and is selectively expressed in vascular endothelium.
Proc Natl Acad Sci U S A
.
1993
;
90
:
7533
-7537.
51
Sait SN, Dougher-Vermazen M, Shows TB, Terman BI. The kinase insert domain receptor gene (KDR) has been relocated to chromosome 4q11 → q12.
Cytogenet Cell Genet
.
1995
;
70
:
145
-146.
52
Fong GH, Rossant J, Gertsenstein M, Breitman ML. Role of the Flt-1 receptor tyrosine kinase in regulating the assembly of vascular endothelium.
Nature
.
1995
;
376
:
66
-70.
53
Shalaby F, Rossant J, Yamaguchi TP, et al. Failure of blood-island formation and vasculogenesis in Flk-1–deficient mice.
Nature
.
1995
;
376
:
62
-66.
54
Gerber HP, Condorelli F, Park J, Ferrara N. Differential transcriptional regulation of the two vascular endothelial growth factor receptor genes: Flt-1, but not Flk-1/KDR, is up-regulated by hypoxia.
J Biol Chem
.
1997
;
272
:
23659
-23667.
55
Keyt BA, Nguyen HV, Berleau LT, et al. Identification of vascular endothelial growth factor determinants for binding KDR and FLT-1 receptors: generation of receptor-selective VEGF variants by site-directed mutagenesis.
J Biol Chem
.
1996
;
271
:
5638
-5646.
56
Millauer B, Wizigmann-Voos S, Schnurch H, et al. High affinity VEGF binding and developmental expression suggest Flk-1 as a major regulator of vasculogenesis and angiogenesis.
Cell
.
1993
;
72
:
835
-846.
57
Barleon B, Sozzani S, Zhou D, Weich HA, Mantovani A, Marme D. Migration of human monocytes in response to vascular endothelial growth factor (VEGF) is mediated via the VEGF receptor flt-1.
Blood
.
1996
;
87
:
3336
-3343.
58
Clauss M, Weich H, Breier G, et al. The vascular endothelial growth factor receptor Flt-1 mediates biologic activities: implications for a functional role of placenta growth factor in monocyte activation and chemotaxis.
J Biol Chem
.
1996
;
271
:
17629
-17634.
59
Charnock-Jones DS, Sharkey AM, Boocock CA, et al. Vascular endothelial growth factor receptor localization and activation in human trophoblast and choriocarcinoma cells.
Biol Reprod
.
1994
;
51
:
524
-530.
60
Takahashi T, Shirasawa T, Miyake K, et al. Protein tyrosine kinases expressed in glomeruli and cultured glomerular cells: Flt-1 and VEGF expression in renal mesangial cells.
Biochem Biophys Res Commun
.
1995
;
209
:
218
-226.
61
Grosskreutz CL, Anand-Apte B, Duplaa C, et al. Vascular endothelial growth factor-induced migration of vascular smooth muscle cells in vitro.
Microvasc Res
.
1999
;
58
:
128
-136.
62
Bellamy WT. Expression of vascular endothelial growth factor and its receptors in multiple myeloma and other hematopoietic malignancies.
Semin Oncol
.
2001
;
28
:
551
-559.
63
Ria R, Roccaro AM, Merchionne F, Vacca A, Dammacco F, Ribatti D. Vascular endothelial growth factor and its receptors in multiple myeloma.
Leukemia
.
2003
;
17
:
1961
-1966.
64
Solovey A, Lin Y, Browne P, Choong S, Wayner E, Hebbel RP. Circulating activated endothelial cells in sickle cell anemia.
N Engl J Med
.
1997
;
337
:
1584
-1590.
65
Peichev M, Naiyer AJ, Pereira D, et al. Expression of VEGFR-2 and AC133 by circulating human CD34(+) cells identifies a population of functional endothelial precursors.
Blood
.
2000
;
95
:
952
-958.
66
Gill M, Dias S, Hattori K, et al. Vascular trauma induces rapid but transient mobilization of VEGFR2(+)AC133(+) endothelial precursor cells.
Circ Res
.
2001
;
88
:
167
-174.
67
Oberg C, Waltenberger J, Claesson-Welsh L, Welsh M. Expression of protein tyrosine kinases in islet cells: possible role of the Flk-1 receptor for beta-cell maturation from duct cells.
Growth Factors
.
1994
;
10
:
115
-126.
68
Yang K, Cepko CL. Flk-1, a receptor for vascular endothelial growth factor (VEGF), is expressed by retinal progenitor cells.
J Neurosci
.
1996
;
16
:
6089
-6099.
69
Katoh O, Tauchi H, Kawaishi K, Kimura A, Satow Y. Expression of the vascular endothelial growth factor (VEGF) receptor gene, KDR, in hematopoietic cells and inhibitory effect of VEGF on apoptotic cell death caused by ionizing radiation.
Cancer Res
.
1995
;
55
:
5687
-5692.
70
Ergun S, Kilic N, Fiedler W, Mukhopadhyay AK. Vascular endothelial growth factor and its receptors in normal human testicular tissue.
Mol Cell Endocrinol
.
1997
;
131
:
9
-20.
71
Brown LF, Detmar M, Tognazzi K, Abu-Jawdeh G, Iruela-Arispe ML. Uterine smooth muscle cells express functional receptors (flt-1 and KDR) for vascular permeability factor/vascular endothelial growth factor.
Lab Invest
.
1997
;
76
:
245
-255.
72
Fong GH, Zhang L, Bryce DM, Peng J. Increased hemangioblast commitment, not vascular disorganization, is the primary defect in flt-1 knock-out mice.
Development
.
1999
;
126
:
3015
-3025.
73
Matsumoto T, Claesson-Welsh L. VEGF receptor signal transduction.
Sci STKE
.
2001
;
2001
:
RE21
.
74
Hiratsuka S, Minowa O, Kuno J, Noda T, Shibuya M. Flt-1 lacking the tyrosine kinase domain is sufficient for normal development and angiogenesis in mice.
Proc Natl Acad Sci U S A
.
1998
;
95
:
9349
-9354.
75
Hattori K, Heissig B, Wu Y, et al. Placental growth factor reconstitutes hematopoiesis by recruiting VEGFR1(+) stem cells from bone-marrow microenvironment.
Nat Med
.
2002
;
8
:
841
-849.
76
Gerber HP, Malik AK, Solar GP, et al. VEGF regulates haematopoietic stem cell survival by an internal autocrine loop mechanism.
Nature
.
2002
;
417
:
954
-958.
77
Sawano A, Iwai S, Sakurai Y, et al. Flt-1, vascular endothelial growth factor receptor 1, is a novel cell surface marker for the lineage of monocyte-macrophages in humans.
Blood
.
2001
;
97
:
785
-791.
78
Luttun A, Tjwa M, Carmeliet P. Placental growth factor (PlGF) and its receptor Flt-1 (VEGFR-1): novel therapeutic targets for angiogenic disorders.
Ann N Y Acad Sci
.
2002
;
979
:
80
-93.
79
LeCouter J, Moritz DR, Li B, et al. Angiogenesis-independent endothelial protection of liver: role of VEGFR-1.
Science
.
2003
;
299
:
890
-893.
80
Hiratsuka S, Nakamura K, Iwai S, et al. MMP9 induction by vascular endothelial growth factor receptor-1 is involved in lung-specific metastasis.
Cancer Cell
.
2002
;
2
:
289
-300.
81
Cunningham SA, Arrate MP, Brock TA, Waxham MN. Interactions of FLT-1 and KDR with phospholipase C gamma: identification of the phosphotyrosine binding sites.
Biochem Biophys Res Commun
.
1997
;
240
:
635
-639.
82
Ito N, Wernstedt C, Engstrom U, Claesson-Welsh L. Identification of vascular endothelial growth factor receptor-1 tyrosine phosphorylation sites and binding of SH2 domain-containing molecules.
J Biol Chem
.
1998
;
273
:
23410
-23418.
83
Wu LW, Mayo LD, Dunbar JD, et al. Utilization of distinct signaling pathways by receptors for vascular endothelial cell growth factor and other mitogens in the induction of endothelial cell proliferation.
J Biol Chem
.
2000
;
275
:
5096
-5103.
84
Takahashi T, Yamaguchi S, Chida K, Shibuya M. A single autophosphorylation site on KDR/Flk-1 is essential for VEGF-A–dependent activation of PLC-gamma and DNA synthesis in vascular endothelial cells.
EMBO J
.
2001
;
20
:
2768
-2778.
85
Wu LW, Mayo LD, Dunbar JD, et al. VRAP is an adaptor protein that binds KDR, a receptor for vascular endothelial cell growth factor.
J Biol Chem
.
2000
;
275
:
6059
-6062.
86
Guo D, Jia Q, Song HY, Warren RS, Donner DB. Vascular endothelial cell growth factor promotes tyrosine phosphorylation of mediators of signal transduction that contain SH2 domains: association with endothelial cell proliferation.
J Biol Chem
.
1995
;
270
:
6729
-6733.
87
Abedi H, Zachary I. Vascular endothelial growth factor stimulates tyrosine phosphorylation and recruitment to new focal adhesions of focal adhesion kinase and paxillin in endothelial cells.
J Biol Chem
.
1997
;
272
:
15442
-15451.
88
Rousseau S, Houle F, Kotanides H, et al. Vascular endothelial growth factor (VEGF)–driven actin-based motility is mediated by VEGFR2 and requires concerted activation of stress-activated protein kinase 2 (SAPK2/p38) and geldanamycin-sensitive phosphorylation of focal adhesion kinase.
J Biol Chem
.
2000
;
275
:
10661
-10672.
89
Igarashi K, Shigeta K, Isohara T, Yamano T, Uno I. Sck interacts with KDR and Flt-1 via its SH2 domain.
Biochem Biophys Res Commun
.
1998
;
251
:
77
-82.
90
Warner AJ, Lopez-Dee J, Knight EL, Feramisco JR, Prigent SA. The Shc-related adaptor protein, Sck, forms a complex with the vascular-endothelial-growth-factor receptor KDR in transfected cells.
Biochem J
.
2000
;
347
:
501
-509.
91
He H, Venema VJ, Gu X, Venema RC, Marrero MB, Caldwell RB. Vascular endothelial growth factor signals endothelial cell production of nitric oxide and prostacyclin through flk-1/KDR activation of c-Src.
J Biol Chem
.
1999
;
274
:
25130
-25135.
92
Eliceiri BP, Paul R, Schwartzberg PL, Hood JD, Leng J, Cheresh DA. Selective requirement for Src kinases during VEGF-induced angiogenesis and vascular permeability.
Mol Cell
.
1999
;
4
:
915
-924.
93
Kroll J, Waltenberger J. The vascular endothelial growth factor receptor KDR activates multiple signal transduction pathways in porcine aortic endothelial cells.
J Biol Chem
.
1997
;
272
:
32521
-32527.
94
Igarashi K, Isohara T, Kato T, Shigeta K, Yamano T, Uno I. Tyrosine 1213 of Flt-1 is a major binding site of Nck and SHP-2.
Biochem Biophys Res Commun
.
1998
;
246
:
95
-99.
95
Gerber HP, McMurtrey A, Kowalski J, et al. Vascular endothelial growth factor regulates endothelial cell survival through the phosphatidylinositol 3′-kinase/Akt signal transduction pathway: requirement for Flk-1/KDR activation.
J Biol Chem
.
1998
;
273
:
30336
-30343.
96
Dimmeler S, Dernbach E, Zeiher AM. Phosphorylation of the endothelial nitric oxide synthase at ser-1177 is required for VEGF-induced endothelial cell migration.
FEBS Lett
.
2000
;
477
:
258
-262.
97
Xia P, Aiello LP, Ishii H, et al. Characterization of vascular endothelial growth factor's effect on the activation of protein kinase C, its isoforms, and endothelial cell growth.
J Clin Invest
.
1996
;
98
:
2018
-2026.
98
Wu HM, Yuan Y, Zawieja DC, Tinsley J, Granger HJ. Role of phospholipase C, protein kinase C, and calcium in VEGF-induced venular hyperpermeability.
Am J Physiol
.
1999
;
276
:
H535
-H542.
99
Takahashi T, Ueno H, Shibuya M. VEGF activates protein kinase C–dependent, but Ras-independent Raf-MEK-MAP kinase pathway for DNA synthesis in primary endothelial cells.
Oncogene
.
1999
;
18
:
2221
-2230.
100
Gliki G, Abu-Ghazaleh R, Jezequel S, Wheeler-Jones C, Zachary I. Vascular endothelial growth factor–induced prostacyclin production is mediated by a protein kinase C (PKC)–dependent activation of extracellular signal-regulated protein kinases 1 and 2 involving PKC-delta and by mobilization of intracellular Ca2+.
Biochem J
.
2001
;
353
:
503
-512.
101
Hood J, Granger HJ. Protein kinase G mediates vascular endothelial growth factor–induced Raf-1 activation and proliferation in human endothelial cells.
J Biol Chem
.
1998
;
273
:
23504
-23508.
102
Parenti A, Morbidelli L, Cui XL, et al. Nitric oxide is an upstream signal of vascular endothelial growth factor-induced extracellular signal-regulated kinase1/2 activation in postcapillary endothelium.
J Biol Chem
.
1998
;
273
:
4220
-4226.
103
Doanes AM, Hegland DD, Sethi R, Kovesdi I, Bruder JT, Finkel T. VEGF stimulates MAPK through a pathway that is unique for receptor tyrosine kinases.
Biochem Biophys Res Commun
.
1999
;
255
:
545
-548.
104
Thakker GD, Hajjar DP, Muller WA, Rosengart TK. The role of phosphatidylinositol 3-kinase in vascular endothelial growth factor signaling.
J Biol Chem
.
1999
;
274
:
10002
-10007.
105
Rousseau S, Houle F, Landry J, Huot J. p38 MAP kinase activation by vascular endothelial growth factor mediates actin reorganization and cell migration in human endothelial cells.
Oncogene
.
1997
;
15
:
2169
-2177.
106
Huser M, Luckett J, Chiloeches A, et al. MEK kinase activity is not necessary for Raf-1 function.
EMBO J
.
2001
;
20
:
1940
-1951.
107
Rahimi N, Kazlauskas A. A role for cadherin-5 in regulation of vascular endothelial growth factor receptor 2 activity in endothelial cells.
Mol Biol Cell
.
1999
;
10
:
3401
-3407.
108
Caveda L, Martin-Padura I, Navarro P, et al. Inhibition of cultured cell growth by vascular endothelial cadherin (cadherin-5/VE-cadherin).
J Clin Invest
.
1996
;
98
:
886
-893.
109
Borges E, Jan Y, Ruoslahti E. Platelet-derived growth factor receptor beta and vascular endothelial growth factor receptor 2 bind to the beta 3 integrin through its extracellular domain.
J Biol Chem
.
2000
;
275
:
39867
-39873.
110
Soker S, Takashima S, Miao HQ, Neufeld G, Klagsbrun M. Neuropilin-1 is expressed by endothelial and tumor cells as an isoform-specific receptor for vascular endothelial growth factor.
Cell
.
1998
;
92
:
735
-745.
111
Dougher AM, Wasserstrom H, Torley L, et al. Identification of a heparin binding peptide on the extracellular domain of the KDR VEGF receptor.
Growth Factors
.
1997
;
14
:
257
-268.
112
Huang L, Sankar S, Lin C, et al. HCPTPA, a protein tyrosine phosphatase that regulates vascular endothelial growth factor receptor-mediated signal transduction and biological activity.
J Biol Chem
.
1999
;
274
:
38183
-38188.
113
Gingras D, Lamy S, Beliveau R. Tyrosine phosphorylation of the vascular endothelial-growth-factor receptor-2 (VEGFR-2) is modulated by Rho proteins.
Biochem J
.
2000
;
348
:
273
-280.
114
Holash J, Maisonpierre PC, Compton D, et al. Vessel co-option, regression, and growth in tumors mediated by angiopoietins and VEGF.
Science
.
1999
;
284
:
1994
-1998.
115
Rafii S, Lyden D, Benezra R, Hattori K, Heissig B. Vascular and haematopoietic stem cells: novel targets for anti-angiogenesis therapy?
Nat Rev Cancer
.
2002
;
2
:
826
-835.
116
Folberg R, Hendrix MJ, Maniotis AJ. Vasculogenic mimicry and tumor angiogenesis.
Am J Pathol
.
2000
;
156
:
361
-381.
117
Chang YS, di Tomaso E, McDonald DM, Jones R, Jain RK, Munn LL. Mosaic blood vessels in tumors: frequency of cancer cells in contact with flowing blood.
Proc Natl Acad Sci U S A
.
2000
;
97
:
14608
-14613.
118
Yancopoulos GD, Davis S, Gale NW, Rudge JS, Wiegand SJ, Holash J. Vascular-specific growth factors and blood vessel formation.
Nature
.
2000
;
407
:
242
-248.
119
Hendrix MJ, Seftor EA, Meltzer PS, et al. Expression and functional significance of VE-cadherin in aggressive human melanoma cells: role in vasculogenic mimicry.
Proc Natl Acad Sci U S A
.
2001
;
98
:
8018
-8023.
120
Folkman J. Can mosaic tumor vessels facilitate molecular diagnosis of cancer?
Proc Natl Acad Sci U S A
.
2001
;
98
:
398
-400.
121
Rafii S. Circulating endothelial precursors: mystery, reality, and promise.
J Clin Invest
.
2000
;
105
:
17
-19.
122
Lyden D, Hattori K, Dias S, et al. Impaired recruitment of bone-marrow–derived endothelial and hematopoietic precursor cells blocks tumor angiogenesis and growth.
Nat Med
.
2001
;
7
:
1194
-1201.
123
Luttun A, Tjwa M, Moons L, et al. Revascularization of ischemic tissues by PlGF treatment, and inhibition of tumor angiogenesis, arthritis and atherosclerosis by anti-Flt1.
Nat Med
.
2002
;
8
:
831
-840.
124
Carmeliet P, Jain RK. Angiogenesis in cancer and other diseases.
Nature
.
2000
;
407
:
249
-257.
125
Hanahan D, Weinberg RA. The hallmarks of cancer.
Cell
.
2000
;
100
:
57
-70.
126
Folkman J.
Harrison's Textbook of Internal Medicine
. 15th ed.
2001
:
517
-530.
127
Fukumura D, Xavier R, Sugiura T, et al. Tumor induction of VEGF promoter activity in stromal cells.
Cell
.
1998
;
94
:
715
-725.
128
Bergers G, Benjamin LE. Tumorigenesis and the angiogenic switch.
Nat Rev Cancer
.
2003
;
3
:
401
-410.
129
Folkman J. Angiogenesis and angiogenesis inhibition: an overview.
Exs
.
1997
;
79
:
1
-8.
130
Carmeliet P. Developmental biology: controlling the cellular brakes.
Nature
.
1999
;
401
:
657
-658.
131
Kerbel RS. Tumor angiogenesis: past, present and the near future.
Carcinogenesis
.
2000
;
21
:
505
-515.
132
Dameron KM, Volpert OV, Tainsky MA, Bouck N. Control of angiogenesis in fibroblasts by p53 regulation of thrombospondin-1.
Science
.
1994
;
265
:
1582
-1584.
133
Bouck N, Stellmach V, Hsu SC. How tumors become angiogenic.
Adv Cancer Res
.
1996
;
69
:
135
-174.
134
Dvorak HF, Nagy JA, Dvorak JT, Dvorak AM. Identification and characterization of the blood vessels of solid tumors that are leaky to circulating macromolecules.
Am J Pathol
.
1988
;
133
:
95
-109.
135
Morikawa S, Baluk P, Kaidoh T, Haskell A, Jain RK, McDonald DM. Abnormalities in pericytes on blood vessels and endothelial sprouts in tumors.
Am J Pathol
.
2002
;
160
:
985
-1000.
136
Baish JW, Jain RK. Fractals and cancer.
Cancer Res
.
2000
;
60
:
3683
-3688.
137
Helmlinger G, Yuan F, Dellian M, Jain RK. Interstitial pH and pO2 gradients in solid tumors in vivo: high-resolution measurements reveal a lack of correlation.
Nat Med
.
1997
;
3
:
177
-182.
138
Brien SE, Zagzag D, Brem S. Rapid in situ cellular kinetics of intracerebral tumor angiogenesis using a monoclonal antibody to bromodeoxyuridine.
Neurosurgery
.
1989
;
25
:
715
-719.
139
Ruoslahti E. Specialization of tumour vasculature.
Nat Rev Cancer
.
2002
;
2
:
83
-90.
140
St Croix B, Rago C, Velculescu V, et al. Genes expressed in human tumor endothelium.
Science
.
2000
;
289
:
1197
-1202.
141
Breier G, Albrecht U, Sterrer S, Risau W. Expression of vascular endothelial growth factor during embryonic angiogenesis and endothelial cell differentiation.
Development
.
1992
;
114
:
521
-532.
142
Jakeman LB, Winer J, Bennett GL, Altar CA, Ferrara N. Binding sites for vascular endothelial growth factor are localized on endothelial cells in adult rat tissues.
J Clin Invest
.
1992
;
89
:
244
-253.
143
Gabrilovich DI, Chen HL, Girgis KR, et al. Production of vascular endothelial growth factor by human tumors inhibits the functional maturation of dendritic cells.
Nat Med
.
1996
;
2
:
1096
-1103.
144
Nakagawa M, Kaneda T, Arakawa T, et al. Vascular endothelial growth factor (VEGF) directly enhances osteoclastic bone resorption and survival of mature osteoclasts.
FEBS Lett
.
2000
;
473
:
161
-164.
145
Henriksen K, Karsdal M, Delaisse JM, Engsig MT. RANKL and vascular endothelial growth factor (VEGF) induce osteoclast chemotaxis through an ERK1/2-dependent mechanism.
J Biol Chem
.
2003
;
278
:
48745
-48753.
146
Midy V, Plouet J. Vasculotropin/vascular endothelial growth factor induces differentiation in cultured osteoblasts.
Biochem Biophys Res Commun
.
1994
;
199
:
380
-386.
147
Melder RJ, Koenig GC, Witwer BP, Safabakhsh N, Munn LL, Jain RK. During angiogenesis, vascular endothelial growth factor and basic fibroblast growth factor regulate natural killer cell adhesion to tumor endothelium.
Nat Med
.
1996
;
2
:
992
-997.
148
Compernolle V, Brusselmans K, Acker T, et al. Loss of HIF-2alpha and inhibition of VEGF impair fetal lung maturation, whereas treatment with VEGF prevents fatal respiratory distress in premature mice.
Nat Med
.
2002
;
8
:
702
-710.
149
Oosthuyse B, Moons L, Storkebaum E, et al. Deletion of the hypoxia-response element in the vascular endothelial growth factor promoter causes motor neuron degeneration.
Nat Genet
.
2001
;
28
:
131
-138.
150
Arora N, Masood R, Zheng T, Cai J, Smith DL, Gill PS. Vascular endothelial growth factor chimeric toxin is highly active against endothelial cells.
Cancer Res
.
1999
;
59
:
183
-188.
151
Cornali E, Zietz C, Benelli R, et al. Vascular endothelial growth factor regulates angiogenesis and vascular permeability in Kaposi's sarcoma.
Am J Pathol
.
1996
;
149
:
1851
-1869.
152
Nakamura S, Murakami-Mori K, Rao N, Weich HA, Rajeev B. Vascular endothelial growth factor is a potent angiogenic factor in AIDS-associated Kaposi's sarcoma–derived spindle cells.
J Immunol
.
1997
;
158
:
4992
-5001.
153
Sakurada S, Kato T, Mashiba K, Mori S, Okamoto T. Involvement of vascular endothelial growth factor in Kaposi's sarcoma associated with acquired immunodeficiency syndrome.
Jpn J Cancer Res
.
1996
;
87
:
1143
-1152.
154
Samaniego F, Markham PD, Gendelman R, et al. Vascular endothelial growth factor and basic fibroblast growth factor present in Kaposi's sarcoma (KS) are induced by inflammatory cytokines and synergize to promote vascular permeability and KS lesion development.
Am J Pathol
.
1998
;
152
:
1433
-1443.
155
Weindel K, Marme D, Weich HA. AIDS-associated Kaposi's sarcoma cells in culture express vascular endothelial growth factor.
Biochem Biophys Res Commun
.
1992
;
183
:
1167
-1174.
156
List AF. Vascular endothelial growth factor signaling pathway as an emerging target in hematologic malignancies.
Oncologist
.
2001
;
6
(suppl 5):
24
-31.
157
Brunner G, Nguyen H, Gabrilove J, Rifkin DB, Wilson EL. Basic fibroblast growth factor expression in human bone marrow and peripheral blood cells.
Blood
.
1993
;
81
:
631
-638.
158
Vacca A, Ribatti D, Roncali L, Dammacco F. Angiogenesis in B cell lymphoproliferative diseases: biological and clinical studies.
Leuk Lymphoma
.
1995
;
20
:
27
-38.
159
Bellamy WT, Richter L, Frutiger Y, Grogan TM. Expression of vascular endothelial growth factor and its receptors in hematopoietic malignancies.
Cancer Res
.
1999
;
59
:
728
-733.
160
Aguayo A, Kantarjian H, Manshouri T, et al. Angiogenesis in acute and chronic leukemias and myelodysplastic syndromes.
Blood
.
2000
;
96
:
2240
-2245.
161
Ridell B, Norrby K. Intratumoral microvascular density in malignant lymphomas of B-cell origin.
Apmis
.
2001
;
109
:
66
-72.
162
Perez-Atayde AR, Sallan SE, Tedrow U, Connors S, Allred E, Folkman J. Spectrum of tumor angiogenesis in the bone marrow of children with acute lymphoblastic leukemia.
Am J Pathol
.
1997
;
150
:
815
-821.
163
Hussong JW, Rodgers GM, Shami PJ. Evidence of increased angiogenesis in patients with acute myeloid leukemia.
Blood
.
2000
;
95
:
309
-313.
164
Lundberg LG, Lerner R, Sundelin P, Rogers R, Folkman J, Palmblad J. Bone marrow in polycythemia vera, chronic myelocytic leukemia, and myelofibrosis has an increased vascularity.
Am J Pathol
.
2000
;
157
:
15
-19.
165
Pruneri G, Bertolini F, Soligo D, et al. Angiogenesis in myelodysplastic syndromes.
Br J Cancer
.
1999
;
81
:
1398
-1401.
166
Mesa RA, Hanson CA, Rajkumar SV, Schroeder G, Tefferi A. Evaluation and clinical correlations of bone marrow angiogenesis in myelofibrosis with myeloid metaplasia.
Blood
.
2000
;
96
:
3374
-3380.
167
Vacca A, Ribatti D, Roncali L, et al. Bone marrow angiogenesis and progression in multiple myeloma.
Br J Haematol
.
1994
;
87
:
503
-508.
168
Vacca A, Ribatti D, Presta M, et al. Bone marrow neovascularization, plasma cell angiogenic potential, and matrix metalloproteinase-2 secretion parallel progression of human multiple myeloma.
Blood
.
1999
;
93
:
3064
-3073.
169
Ribatti D, Vacca A, Nico B, et al. Bone marrow angiogenesis and mast cell density increase simultaneously with progression of human multiple myeloma.
Br J Cancer
.
1999
;
79
:
451
-455.
170
Munshi NW, Penn J. Angiogenesis in newly diagnosed multiple myeloma: poor prognosis with increased microvessel density (MVD) in bone marrow biopsies [abstract].
Blood
.
1998
;
92
:
98a
.
171
Sezer O, Niemoller K, Eucker J, et al. Bone marrow microvessel density is a prognostic factor for survival in patients with multiple myeloma.
Ann Hematol
.
2000
;
79
:
574
-577.
172
Rajkumar SV, Leong T, Roche PC, et al. Prognostic value of bone marrow angiogenesis in multiple myeloma.
Clin Cancer Res
.
2000
;
6
:
3111
-3116.
173
Kumar S, Fonseca R, Dispenzieri A, et al. Prognostic value of angiogenesis in solitary bone plasmacytoma.
Blood
.
2003
;
101
:
1715
-1717.
174
Singhal S, Mehta J, Desikan R, et al. Antitumor activity of thalidomide in refractory multiple myeloma.
N Engl J Med
.
1999
;
341
:
1565
-1571.
175
Rajkumar SV, Fonseca R, Witzig TE, Gertz MA, Greipp PR. Bone marrow angiogenesis in patients achieving complete response after stem cell transplantation for multiple myeloma.
Leukemia
.
1999
;
13
:
469
-472.
176
Kumar S, Witzig TE, Dispenzieri A, et al. Effect of thalidomide therapy on bone marrow angiogenesis in multiple myeloma.
Leukemia
.
2004
;
18
:
624
-627.
177
Hlatky L, Hahnfeldt P, Folkman J. Clinical application of antiangiogenic therapy: microvessel density, what it does and doesn't tell us.
J Natl Cancer Inst
.
2002
;
94
:
883
-893.
178
Bertolini F, Mingrone W, Alietti A, et al. Thalidomide in multiple myeloma, myelodysplastic syndromes and histiocytosis: analysis of clinical results and of surrogate angiogenesis markers.
Ann Oncol
.
2001
;
12
:
987
-990.
179
Streubel B, Chott A, Huber D, et al. Lymphoma-specific genetic aberrations in microvascular endothelial cells in B-cell lymphomas.
N Engl J Med
.
2004
;
351
:
250
-259.
180
Vacca A, Ria R, Semeraro F, et al. Endothelial cells in the bone marrow of patients with multiple myeloma.
Blood
.
2003
;
102
:
3340
-3348.
181
Fiedler W, Graeven U, Ergun S, et al. Vascular endothelial growth factor, a possible paracrine growth factor in human acute myeloid leukemia.
Blood
.
1997
;
89
:
1870
-1875.
182
Chen H, Treweeke AT, West DC, et al. In vitro and in vivo production of vascular endothelial growth factor by chronic lymphocytic leukemia cells.
Blood
.
2000
;
96
:
3181
-3187.
183
Dias S, Hattori K, Zhu Z, et al. Autocrine stimulation of VEGFR-2 activates human leukemic cell growth and migration.
J Clin Invest
.
2000
;
106
:
511
-521.
184
Krauth MT, Simonitsch I, Aichberger KJ, et al. Immunohistochemical detection of VEGF in the bone marrow of patients with chronic myeloid leukemia and correlation with the phase of disease.
Am J Clin Pathol
.
2004
;
121
:
473
-481.
185
Ghannadan M, Wimazal F, Simonitsch I, et al. Immunohistochemical detection of VEGF in the bone marrow of patients with acute myeloid leukemia: correlation between VEGF expression and the FAB category.
Am J Clin Pathol
.
2003
;
119
:
663
-671.
186
Dankbar B, Padro T, Leo R, et al. Vascular endothelial growth factor and interleukin-6 in paracrine tumor-stromal cell interactions in multiple myeloma.
Blood
.
2000
;
95
:
2630
-2636.
187
Kumar S, Witzig TE, Timm M, et al. Expression of VEGF and its receptors by myeloma cells.
Leukemia
.
2003
;
17
:
2025
-2031.
188
Lin B, Podar K, Gupta D, et al. The vascular endothelial growth factor receptor tyrosine kinase inhibitor PTK787/ZK222584 inhibits growth and migration of multiple myeloma cells in the bone marrow microenvironment.
Cancer Res
.
2002
;
62
:
5019
-5026.
189
Dias S, Hattori K, Heissig B, et al. Inhibition of both paracrine and autocrine VEGF/VEGFR-2 signaling pathways is essential to induce long-term remission of xenotransplanted human leukemias.
Proc Natl Acad Sci U S A
.
2001
;
98
:
10857
-10862.
190
Dias S, Shmelkov SV, Lam G, Rafii S. VEGF(165) promotes survival of leukemic cells by Hsp90-mediated induction of Bcl-2 expression and apoptosis inhibition.
Blood
.
2002
;
99
:
2532
-2540.
191
Podar K, Tai YT, Lin BK, et al. Vascular endothelial growth factor-induced migration of multiple myeloma cells is associated with beta 1 integrin- and phosphatidylinositol 3-kinase-dependent PKC alpha activation.
J Biol Chem
.
2002
;
277
:
7875
-7881.
192
Yaccoby S, Barlogie B, Epstein J. Primary myeloma cells growing in SCID-hu mice: a model for studying the biology and treatment of myeloma and its manifestations.
Blood
.
1998
;
92
:
2908
-2913.
193
Browder TM, Dunbar CE, Nienhuis AW. Private and public autocrine loops in neoplastic cells.
Cancer Cells
.
1989
;
1
:
9
-17.
194
Huang SS, Huang JS. Rapid turnover of the platelet-derived growth factor receptor in sis-transformed cells and reversal by suramin: implications for the mechanism of autocrine transformation.
J Biol Chem
.
1988
;
263
:
12608
-12618.
195
Lang RA, Metcalf D, Gough NM, Dunn AR, Gonda TJ. Expression of a hemopoietic growth factor cDNA in a factor-dependent cell line results in autonomous growth and tumorigenicity.
Cell
.
1985
;
43
:
531
-542.
196
Kitani A, Hara M, Hirose T, et al. Autostimulatory effects of IL-6 on excessive B cell differentiation in patients with systemic lupus erythematosus: analysis of IL-6 production and IL-6R expression.
Clin Exp Immunol
.
1992
;
88
:
75
-83.
197
Lu C, Kerbel RS. Interleukin-6 undergoes transition from paracrine growth inhibitor to autocrine stimulator during human melanoma progression.
J Cell Biol
.
1993
;
120
:
1281
-1288.
198
Rogers SY, Bradbury D, Kozlowski R, Russell NH. Evidence for internal autocrine regulation of growth in acute myeloblastic leukemia cells.
Exp Hematol
.
1994
;
22
:
593
-598.
199
Santos SC, Dias S. Internal and external autocrine VEGF/KDR loops regulate survival of subsets of acute leukemia through distinct signaling pathways.
Blood
.
2004
;
103
:
3883
-3889.
200
Kibler C, Schermutzki F, Waller HD, Timpl R, Muller CA, Klein G. Adhesive interactions of human multiple myeloma cell lines with different extracellular matrix molecules.
Cell Adhes Commun
.
1998
;
5
:
307
-323.
201
Damiano JS, Cress AE, Hazlehurst LA, Shtil AA, Dalton WS. Cell adhesion mediated drug resistance (CAM-DR): role of integrins and resistance to apoptosis in human myeloma cell lines.
Blood
.
1999
;
93
:
1658
-1667.
202
Jensen GS, Belch AR, Mant MJ, Ruether BA, Yacyshyn BR, Pilarski LM. Expression of multiple beta 1 integrins on circulating monoclonal B cells in patients with multiple myeloma.
Am J Hematol
.
1993
;
43
:
29
-36.
203
Uchiyama H, Barut BA, Mohrbacher AF, Chauhan D, Anderson KC. Adhesion of human myeloma-derived cell lines to bone marrow stromal cells stimulates interleukin-6 secretion.
Blood
.
1993
;
82
:
3712
-3720.
204
Uchiyama H, Barut BA, Chauhan D, Cannistra SA, Anderson KC. Characterization of adhesion molecules on human myeloma cell lines.
Blood
.
1992
;
80
:
2306
-2314.
205
Gupta D, Treon SP, Shima Y, et al. Adherence of multiple myeloma cells to bone marrow stromal cells upregulates vascular endothelial growth factor secretion: therapeutic applications.
Leukemia
.
2001
;
15
:
1950
-1961.
206
Mitsiades CS, Mitsiades NS, McMullan CJ, et al. Inhibition of the insulin-like growth factor receptor-1 tyrosine kinase activity as a therapeutic strategy for multiple myeloma, other hematologic malignancies, and solid tumors.
Cancer Cell
.
2004
;
5
:
221
-230.
207
Menu E, Kooijman R, Van Valckenborgh E, et al. Specific roles for the PI3K and the MEK-ERK pathway in IGF-1–stimulated chemotaxis, VEGF secretion and proliferation of multiple myeloma cells: study in the 5T33MM model.
Br J Cancer
.
2004
;
90
:
1076
-1083.
208
Fukuda R, Hirota K, Fan F, Jung YD, Ellis LM, Semenza GL. Insulin-like growth factor 1 induces hypoxia-inducible factor 1–mediated vascular endothelial growth factor expression, which is dependent on MAP kinase and phosphatidylinositol 3–kinase signaling in colon cancer cells.
J Biol Chem
.
2002
;
277
:
38205
-38211.
209
Hurt EM, Wiestner A, Rosenwald A, et al. Overexpression of c-maf is a frequent oncogenic event in multiple myeloma that promotes proliferation and pathological interactions with bone marrow stroma.
Cancer Cell
.
2004
;
5
:
191
-199.
210
Tai YT, Podar K, Gupta D, et al. CD40 activation induces p53-dependent vascular endothelial growth factor secretion in human multiple myeloma cells.
Blood
.
2002
;
99
:
1419
-1427.
211
Mayerhofer M, Valent P, Sperr WR, Griffin JD, Sillaber C. BCR/ABL induces expression of vascular endothelial growth factor and its transcriptional activator, hypoxia inducible factor-1alpha, through a pathway involving phosphoinositide 3-kinase and the mammalian target of rapamycin.
Blood
.
2002
;
100
:
3767
-3775.
212
Hattori K, Dias S, Heissig B, et al. Vascular endothelial growth factor and angiopoietin-1 stimulate postnatal hematopoiesis by recruitment of vasculogenic and hematopoietic stem cells.
J Exp Med
.
2001
;
193
:
1005
-1014.
213
Hayashi T, Hideshima T, Akiyama M, et al. Ex vivo induction of multiple myeloma-specific cytotoxic T lymphocytes.
Blood
.
2003
;
102
:
1435
-1442.
214
Le Gouill S, Podar K, Amiot M, et al. VEGF induces MCL-1 upregulation and protects multiple myeloma cells against apoptosis.
Blood
.
2004
;
104
:
2886
-2892.
215
Smart EJ, Graf GA, McNiven MA, et al. Caveolins, liquid-ordered domains, and signal transduction.
Mol Cell Biol
.
1999
;
19
:
7289
-7304.
216
Simons K, Toomre D. Lipid rafts and signal transduction.
Nat Rev Mol Cell Biol
.
2000
;
1
:
31
-39.
217
Podar K, Tai YT, Cole CE, et al. Essential role of caveolae in interleukin-6– and insulin-like growth factor I–triggered Akt-1–mediated survival of multiple myeloma cells.
J Biol Chem
.
2003
;
278
:
5794
-5801.
218
Kim KJ, Li B, Winer J, et al. Inhibition of vascular endothelial growth factor–induced angiogenesis suppresses tumour growth in vivo.
Nature
.
1993
;
362
:
841
-844.
219
Inoue M, Hager JH, Ferrara N, Gerber HP, Hanahan D. VEGF-A has a critical, nonredundant role in angiogenic switching and pancreatic beta cell carcinogenesis.
Cancer Cell
.
2002
;
1
:
193
-202.
220
Ferrara N, Hillan KJ, Gerber HP, Novotny W. Discovery and development of bevacizumab, an anti-VEGF antibody for treating cancer.
Nat Rev Drug Discov
.
2004
;
3
:
391
-400.
221
Hurwitz H, Fehrenbacher L, Novotny W, et al. Bevacizumab plus irinotecan, fluorouracil, and leucovorin for metastatic colorectal cancer.
N Engl J Med
.
2004
;
350
:
2335
-2342.
222
Yang JC, Haworth L, Sherry RM, et al. A randomized trial of bevacizumab, an anti-vascular endothelial growth factor antibody, for metastatic renal cancer.
N Engl J Med
.
2003
;
349
:
427
-434.
223
Yang JC, Sherry RM, Steinberg SM, et al. Randomized study of high-dose and low-dose interleukin-2 in patients with metastatic renal cancer.
J Clin Oncol
.
2003
;
21
:
3127
-3132.
224
Johnson DH, Fehrenbacher L, Novotny WF, et al. Randomized phase II trial comparing bevacizumab plus carboplatin and paclitaxel with carboplatin and paclitaxel alone in previously untreated locally advanced or metastatic non-small-cell lung cancer.
J Clin Oncol
.
2004
;
22
:
2184
-2191.
225
Sandler AB, Johnson DH, Herbst RS. Anti-vascular endothelial growth factor monoclonals in non-small cell lung cancer.
Clin Cancer Res
.
2004
;
10
:
4258s
-4262s.
226
Diaz-Rubio E. New chemotherapeutic advances in pancreatic, colorectal, and gastric cancers.
Oncologist
.
2004
;
9
:
282
-294.
227
Rugo HS. Bevacizumab in the treatment of breast cancer: rationale and current data.
Oncologist
.
2004
;
1
(suppl 9):
43
-49.
228
Rini BI, Halabi S, Taylor J, Small EJ, Schilsky RL. Cancer and Leukemia Group B 90206: a randomized phase III trial of interferon-alpha or interferon-alpha plus anti-vascular endothelial growth factor antibody (bevacizumab) in metastatic renal cell carcinoma.
Clin Cancer Res
.
2004
;
10
:
2584
-2586.
229
Willett CG, Boucher Y, di Tomaso E, et al. Direct evidence that the VEGF-specific antibody bevacizumab has antivascular effects in human rectal cancer.
Nat Med
.
2004
;
10
:
145
-147.
230
Gerber HP, Kowalski J, Sherman D, Eberhard DA, Ferrara N. Complete inhibition of rhabdomyosarcoma xenograft growth and neovascularization requires blockade of both tumor and host vascular endothelial growth factor.
Cancer Res
.
2000
;
60
:
6253
-6258.
231
Holash J, Davis S, Papadopoulos N, et al. VEGF-Trap: a VEGF blocker with potent antitumor effects.
Proc Natl Acad Sci U S A
.
2002
;
99
:
11393
-11398.
232
Kim ES, Serur A, Huang J, et al. Potent VEGF blockade causes regression of co-opted vessels in a model of neuroblastoma.
Proc Natl Acad Sci U S A
.
2002
;
99
:
11399
-11404.
233
Wood JM, Bold G, Buchdunger E, et al. PTK787/ZK 222584, a novel and potent inhibitor of vascular endothelial growth factor receptor tyrosine kinases, impairs vascular endothelial growth factor-induced responses and tumor growth after oral administration.
Cancer Res
.
2000
;
60
:
2178
-2189.
234
Thomas AL, Morgan B, Drevs J, et al. Vascular endothelial growth factor receptor tyrosine kinase inhibitors: PTK787/ZK 222584.
Semin Oncol
.
2003
;
30
:
32
-38.
235
Kumar R, Hopper TM, Miller CG, et al. Discovery and biological evaluation of GW654652: a pan inhibitor of VEGF receptors [abstract].
Proc Am Assoc Cancer Res
.
2003
;
44
:
9
.
236
Cheung M, Boloor A, Hinkle KW, et al. Discovery of indazolylpyrimidines as potent inhibitors of VEGFR2 tyrosine kinase [abstract].
Proc Am Assoc Cancer Res
.
2003
;
44
:
9
.
237
Podar K, Catley LP, Tai YT, et al. GW654652, the pan-inhibitor of VEGF receptors, blocks the growth and migration of multiple myeloma cells in the bone marrow microenvironment.
Blood
.
2004
;
103
:
3474
-3479.
238
O'Farrell AM, Yuen HA, Smolich B, et al. Effects of SU5416, a small molecule tyrosine kinase receptor inhibitor, on FLT3 expression and phosphorylation in patients with refractory acute myeloid leukemia.
Leuk Res
.
2004
;
28
:
679
-689.
239
Giles FJ, Stopeck AT, Silverman LR, et al. SU5416, a small molecule tyrosine kinase receptor inhibitor, has biologic activity in patients with refractory acute myeloid leukemia or myelodysplastic syndromes.
Blood
.
2003
;
102
:
795
-801.
240
Fiedler W, Mesters R, Tinnefeld H, et al. A phase 2 clinical study of SU5416 in patients with refractory acute myeloid leukemia.
Blood
.
2003
;
102
:
2763
-2767.
241
O'Farrell AM, Abrams TJ, Yuen HA, et al. SU11248 is a novel FLT3 tyrosine kinase inhibitor with potent activity in vitro and in vivo.
Blood
.
2003
;
101
:
3597
-3605.
242
Beebe JS, Jani JP, Knauth E, et al. Pharmacological characterization of CP-547,632, a novel vascular endothelial growth factor receptor-2 tyrosine kinase inhibitor for cancer therapy.
Cancer Res
.
2003
;
63
:
7301
-7309.
243
Bates D. ZD-6474. AstraZeneca.
Curr Opin Investig Drugs
.
2003
;
4
:
1468
-1472.
244
Lowinger TB, Riedl B, Dumas J, Smith RA. Design and discovery of small molecules targeting raf-1 kinase.
Curr Pharm Des
.
2002
;
8
:
2269
-2278.
245
Richly H, Kupsch P, Passage K, et al. A phase I clinical and pharmacokinetic study of the Raf kinase inhibitor (RKI) BAY 43-9006 administered in combination with doxorubicin in patients with solid tumors.
Int J Clin Pharmacol Ther
.
2003
;
41
:
620
-621.
246
D'Amato RJ, Loughnan MS, Flynn E, Folkman J. Thalidomide is an inhibitor of angiogenesis.
Proc Natl Acad Sci U S A
.
1994
;
91
:
4082
-4085.
247
Bartlett JB, Dredge K, Dalgleish AG. The evolution of thalidomide and its IMiD derivatives as anticancer agents.
Nat Rev Cancer
.
2004
;
4
:
314
-322.
248
Hideshima T, Chauhan D, Shima Y, et al. Thalidomide and its analogs overcome drug resistance of human multiple myeloma cells to conventional therapy.
Blood
.
2000
;
96
:
2943
-2950.
249
D'Amato RJ, Lentzsch S, Anderson KC, Rogers MS. Mechanism of action of thalidomide and 3-aminothalidomide in multiple myeloma.
Semin Oncol
.
2001
;
28
:
597
-601.
250
Davies FE, Raje N, Hideshima T, et al. Thalidomide and immunomodulatory derivatives augment natural killer cell cytotoxicity in multiple myeloma.
Blood
.
2001
;
98
:
210
-216.
251
Richardson PG, Schlossman RL, Weller E, et al. Immunomodulatory drug CC-5013 overcomes drug resistance and is well tolerated in patients with relapsed multiple myeloma.
Blood
.
2002
;
100
:
3063
-3067.
252
Schey SA, Fields P, Bartlett JB, et al. Phase I study of an immunomodulatory thalidomide analog, CC-4047, in relapsed or refractory multiple myeloma.
J Clin Oncol
.
2004
;
22
:
3269
-3276.
253
Cushman M, He HM, Katzenellenbogen JA, Lin CM, Hamel E. Synthesis, antitubulin and antimitotic activity, and cytotoxicity of analogs of 2-methoxyestradiol, an endogenous mammalian metabolite of estradiol that inhibits tubulin polymerization by binding to the colchicine binding site.
J Med Chem
.
1995
;
38
:
2041
-2049.
254
Klauber N, Parangi S, Flynn E, Hamel E, D'Amato RJ. Inhibition of angiogenesis and breast cancer in mice by the microtubule inhibitors 2-methoxyestradiol and taxol.
Cancer Res
.
1997
;
57
:
81
-86.
255
Lottering ML, Haag M, Seegers JC. Effects of 17 beta-estradiol metabolites on cell cycle events in MCF-7 cells.
Cancer Res
.
1992
;
52
:
5926
-5932.
256
Mukhopadhyay T, Roth JA. Induction of apoptosis in human lung cancer cells after wild-type p53 activation by methoxyestradiol.
Oncogene
.
1997
;
14
:
379
-384.
257
Schumacher G, Neuhaus P. The physiologic estrogen metabolite 2-methoxyestradiol reduces tumor growth and induces apoptosis in human solid tumors.
J Cancer Res Clin Oncol
.
2001
;
127
:
405
-410.
258
Kumar AP, Garcia GE, Slaga TJ. 2-methoxyestradiol blocks cell-cycle progression at G(2)/M phase and inhibits growth of human prostate cancer cells.
Mol Carcinog
.
2001
;
31
:
111
-124.
259
Chauhan D, Catley L, Hideshima T, et al. 2-Methoxyestradiol overcomes drug resistance in multiple myeloma cells.
Blood
.
2002
;
100
:
2187
-2194.
260
Keyes K, Cox K, Treadway P, et al. An in vitro tumor model: analysis of angiogenic factor expression after chemotherapy.
Cancer Res
.
2002
;
62
:
5597
-5602.
261
Keyes KA, Mann L, Sherman M, et al. LY317615 decreases plasma VEGF levels in human tumor xenograft-bearing mice.
Cancer Chemother Pharmacol
.
2004
;
53
:
133
-140.
262
Herbst RS. Targeted therapy using novel agents in the treatment of non-small-cell lung cancer.
Clin Lung Cancer
.
2002
;
3
(suppl 1):
S30
-S38.
263
MacDonald TJ, Taga T, Shimada H, et al. Preferential susceptibility of brain tumors to the antiangiogenic effects of an alpha(v) integrin antagonist.
Neurosurgery
.
2001
;
48
:
151
-157.
264
Burke PA, DeNardo SJ, Miers LA, Lamborn KR, Matzku S, DeNardo GL. Cilengitide targeting of alpha(v)beta(3) integrin receptor synergizes with radioimmunotherapy to increase efficacy and apoptosis in breast cancer xenografts.
Cancer Res
.
2002
;
62
:
4263
-4272.
265
Raguse JD, Gath HJ, Bier J, Riess H, Oettle H. Cilengitide (EMD 121974) arrests the growth of a heavily pretreated highly vascularised head and neck tumour.
Oral Oncol
.
2004
;
40
:
228
-230.
266
Nisato RE, Tille JC, Jonczyk A, Goodman SL, Pepper MS. alphav beta 3 and alphav beta 5 integrin antagonists inhibit angiogenesis in vitro.
Angiogenesis
.
2003
;
6
:
105
-119.
267
Moolenaar WH, Kranenburg O, Postma FR, Zondag GC. Lysophosphatidic acid: G-protein signalling and cellular responses.
Curr Opin Cell Biol
.
1997
;
9
:
168
-173.
268
Hu YL, Tee MK, Goetzl EJ, et al. Lysophosphatidic acid induction of vascular endothelial growth factor expression in human ovarian cancer cells.
J Natl Cancer Inst
.
2001
;
93
:
762
-768.
269
Hideshima T, Chauhan D, Hayashi T, et al. Antitumor activity of lysophosphatidic acid acyltransferase-beta inhibitors, a novel class of agents, in multiple myeloma.
Cancer Res
.
2003
;
63
:
8428
-8436.
270
Kane RC, Bross PF, Farrell AT, Pazdur R. Velcade: US FDA approval for the treatment of multiple myeloma progressing on prior therapy.
Oncologist
.
2003
;
8
:
508
-513.
271
Hideshima T, Richardson P, Chauhan D, et al. The proteasome inhibitor PS-341 inhibits growth, induces apoptosis, and overcomes drug resistance in human multiple myeloma cells.
Cancer Res
.
2001
;
61
:
3071
-3076.
272
Hideshima T, Mitsiades C, Akiyama M, et al. Molecular mechanisms mediating antimyeloma activity of proteasome inhibitor PS-341.
Blood
.
2003
;
101
:
1530
-1534.
273
Hideshima T, Chauhan D, Hayashi T, et al. Proteasome inhibitor PS-341 abrogates IL-6 triggered signaling cascades via caspase-dependent down-regulation of gp130 in multiple myeloma.
Oncogene
.
2003
;
22
:
8386
-8393.
274
Nawrocki ST, Bruns CJ, Harbison MT, et al. Effects of the proteasome inhibitor PS-341 on apoptosis and angiogenesis in orthotopic human pancreatic tumor xenografts.
Mol Cancer Ther
.
2002
;
1
:
1243
-1253.
275
Oikawa T, Sasaki T, Nakamura M, et al. The proteasome is involved in angiogenesis.
Biochem Biophys Res Commun
.
1998
;
246
:
243
-248.
276
LeBlanc R, Catley LP, Hideshima T, et al. Proteasome inhibitor PS-341 inhibits human myeloma cell growth in vivo and prolongs survival in a murine model.
Cancer Res
.
2002
;
62
:
4996
-5000.
277
Tai YT, Catley LP, Mitsiades CS, et al. Mechanisms by which SGN-40, a humanized anti-CD40 antibody, induces cytotoxicity in human multiple myeloma cells: clinical implications.
Cancer Res
.
2004
;
64
:
2846
-2852.
278
Gorski DH, Beckett MA, Jaskowiak NT, et al. Blockage of the vascular endothelial growth factor stress response increases the antitumor effects of ionizing radiation.
Cancer Res
.
1999
;
59
:
3374
-3378.
279
Sweeney CJ, Miller KD, Sissons SE, et al. The antiangiogenic property of docetaxel is synergistic with a recombinant humanized monoclonal antibody against vascular endothelial growth factor or 2-methoxyestradiol but antagonized by endothelial growth factors.
Cancer Res
.
2001
;
61
:
3369
-3372.
280
Tran J, Master Z, Yu JL, Rak J, Dumont DJ, Kerbel RS. A role for survivin in chemoresistance of endothelial cells mediated by VEGF.
Proc Natl Acad Sci U S A
.
2002
;
99
:
4349
-4354.
281
Jain RK. Normalizing tumor vasculature with anti-angiogenic therapy: a new paradigm for combination therapy.
Nat Med
.
2001
;
7
:
987
-989.
282
Teicher BA, Sotomayor EA, Huang ZD. Antiangiogenic agents potentiate cytotoxic cancer therapies against primary and metastatic disease.
Cancer Res
.
1992
;
52
:
6702
-6704.
283
Kakeji Y, Teicher BA. Preclinical studies of the combination of angiogenic inhibitors with cytotoxic agents.
Invest New Drugs
.
1997
;
15
:
39
-48.
284
Klement G, Baruchel S, Rak J, et al. Continuous low-dose therapy with vinblastine and VEGF receptor-2 antibody induces sustained tumor regression without overt toxicity.
J Clin Invest
.
2000
;
105
:
R15
-R24.
285
Lee CG, Heijn M, di Tomaso E, et al. Anti-vascular endothelial growth factor treatment augments tumor radiation response under normoxic or hypoxic conditions.
Cancer Res
.
2000
;
60
:
5565
-5570.
286
Kozin SV, Boucher Y, Hicklin DJ, Bohlen P, Jain RK, Suit HD. Vascular endothelial growth factor receptor-2-blocking antibody potentiates radiation-induced long-term control of human tumor xenografts.
Cancer Res
.
2001
;
61
:
39
-44.
287
Hanahan D, Bergers G, Bergsland E. Less is more, regularly: metronomic dosing of cytotoxic drugs can target tumor angiogenesis in mice.
J Clin Invest
.
2000
;
105
:
1045
-1047.
288
Kerbel RS, Kamen BA. The anti-angiogenic basis of metronomic chemotherapy.
Nat Rev Cancer
.
2004
;
4
:
423
-436.
289
Browder T, Butterfield CE, Kraling BM, et al. Anti-angiogenic scheduling of chemotherapy improves efficacy against experimental drug-resistant cancer.
Cancer Res
.
2000
;
60
:
1878
-1886.
290
Gasparini G. Metronomic scheduling: the future of chemotherapy?
Lancet Oncol
.
2001
;
2
:
733
-740.
291
Kamen BA, Rubin E, Aisner J, Glatstein E. High-time chemotherapy or high time for low dose.
J Clin Oncol
.
2000
;
18
:
2935
-2937.
292
Kerbel RS, Klement G, Pritchard KI, Kamen B. Continuous low-dose anti-angiogenic/metronomic chemotherapy: from the research laboratory into the oncology clinic.
Ann Oncol
.
2002
;
13
:
12
-15.
Sign in via your Institution