There appear to be 2 pathways involved in the early pathogenesis of premalignant monoclonal gammopathy of undetermined significance (MGUS) and malignant multiple myeloma (MM) tumors. Nearly half of these tumors are nonhyperdiploid and mostly have immunoglobulin H (IgH) translocations that involve 5 recurrent chromosomal loci, including 11q13 (cyclin D1), 6p21 (cyclin D3), 4p16 (fibroblast growth factor receptor 3 [FGFR3] and multiple myeloma SET domain [MMSET]), 16q23 (c-maf), and 20q11 (mafB). The remaining tumors are hyperdiploid and contain multiple trisomies involving chromosomes 3, 5, 7, 9, 11, 15, 19, and 21, but infrequently have IgH translocations involving the 5 recurrent loci. Dysregulated expression of cyclin D1, D2, or D3 appears to occur as an early event in virtually all of these tumors. This may render the cells more susceptible to proliferative stimuli, resulting in selective expansion as a result of interaction with bone marrow stromal cells that produce interleukin-6 (IL-6) and other cytokines. There are 5 proposed tumor groups, defined by IgH translocations and/or cyclin D expression, that appear to have differences in biologic properties, including interaction with stromal cells, prognosis, and response to specific therapies. Delineation of the mechanisms mediating MM cell proliferation, survival, and migration in the bone marrow (BM) microenvironment may both enhance understanding of pathogenesis and provide the framework for identification and validation of novel molecular targets.

On January 1, 2000, there were estimated to be 47 000 patients with multiple myeloma (MM) in the United States, reflecting a yearly incidence of nearly 14 000 and a median survival of about 3 years.1Ā  Currently it remains an incurable malignancy that often is preceded by an exceptionally common (3.4% of the population over the age of 502Ā ) premalignant tumor, monoclonal gammopathy of undetermined significance (MGUS). Monoclonal gammopathies are usually asymptomatic, but they may sometimes cause primary amyloidosis as a result of pathologic, and ultimately lethal, deposits of monoclonal immunoglobulin (Ig) in critical tissues.3Ā  Although MGUS is stable, it stochastically progresses to frankly malignant MM at a rate of 0.6% to 3% per year, depending on the level of monoclonal Ig.4Ā  For both MGUS and MM, the incidence is markedly age dependent, about 2-fold higher in American blacks than whites, and significantly higher in males.5Ā  Although for many years the incidence of MM appeared to be increasing, since 1992 the incidence appears to have become stable. The roles of genetic background and environment are poorly defined, although there may be clustering within families.6Ā 

Germinal center B cells uniquely modify the DNA of Ig genes through sequential rounds of somatic hypermutation and antigen selection, and also by IgH switch recombination. Postgerminal center B cells can generate plasmablasts (PBs) that have successfully completed somatic hypermutation and IgH switching before migrating to the bone marrow (BM), where stromal cells enable terminal differentiation into long-lived plasma cells (PCs).7,8Ā  MGUS and MM are characterized by the accumulation of transformed PBs/PCs at multiple sites in the BM. Importantly, although MM is more proliferative than MGUS, both tumors have an extremely low rate of proliferation, typically with less than 1% of cells synthesizing DNA until late stages of MM. The combination of karyotypic complexity, an inability to efficiently perform conventional cytogenetics on low proliferative tumors, and the telomeric location of some translocation partners delayed the identification of Ig translocations in MGUS and MM. An important initial step in solving this problem was the identification and cloning of IgH switch region translocation breakpoints in human myeloma cell lines (HMCLs).9Ā  Interphase fluorescence in situ hybridization (FISH) using probes flanking the cloned breakpoints identifies karyotypic abnormalities even in nondividing cells and enabled the analysis of primary MGUS and MM tumors.10,11Ā  Several studies have shown that a majority of MM tumors have an IgH translocation that nonrandomly involves one of many potential chromosomal partners.9,12-14Ā  The prevalence of IgH translocations varies with the stage of disease: 46% to 48% in MGUS or smoldering MM (SMM), 55% to 73% in intramedullary MM, 85% in primary plasma cell leukemia, and more than 90% in HMCLs.8,14Ā 

There are 5 well-defined recurrent chromosomal partners (oncogenes) that are involved in IgH translocations in MGUS and MM: 11q13 (cyclin D1), 6p21 (cyclin D3), 4p16 (fibroblast growth factor receptor 3 [FGFR3] and multiple myeloma SET domain [MMSET]), 16q23 (c-maf), and 20q11 (mafB).9Ā  Together the combined prevalence of these 5 IgH translocation partners is about 40%, with approximately 15% 11q13, 3% 6p21, 15% 4p16, 5% 16q23, and 2% 20q11.8,12,15-18Ā  The t(4;14) translocation is unusual in that it appears to dysregulate 2 potential oncogenes, MMSET on der(4) and FGFR3 on der(14), although FGFR3 on der(14) is lost or not expressed in about 20% of MM tumors that have a t(4;14) translocation.19-23Ā  The apparently lower incidence of 4p16 and/or 16q23 in MGUS/SMM compared with MM may be due to these translocations resulting in de novo MM without preceding MGUS, or a more rapid progression of MGUS to MM, a hypothesis supported by the fact that patients with translocations involving 4p16 or 16q23 have an extremely poor prognosis.12,13,22,24Ā 

Primary translocations occur as early and perhaps initiating events during tumor pathogenesis, whereas secondary translocations occur as progression events. Most translocations involving the 5 recurrent translocation partners appear to be primary translocations that occurred from errors in IgH switch recombination during B-cell development in germinal centers. In contrast, translocations of c-myc appear to be very late secondary events that do not involve B-cellā€“specific recombination mechanisms, are often complex, and sometimes do not involve Ig loci. By FISH analysis, rearrangements of c-myc are reported in only 15% of MM tumors (with frequent heterogeneity within a tumor), but in nearly 40% of advanced MM tumors and 90% of HMCLs.25,26Ā  Regarding the approximately 20% of IgH translocations not involving the 6 recurrent partners, little is known about the multitude of partners and oncogenes, the mechanisms that mediate these translocations, or the time(s) at which these translocations occur.

MGUS and MM appear closer to normal, nonproliferating PCs than to normal, but highly proliferating PBs, for which 30% or more of the cells can be in S phase. It is surprising therefore that analysis by Bergsagel and Kuehl27Ā  of combined gene expression profiling data published from 2 laboratories28,29Ā  shows that the expression level of cyclin D1, cyclin D2, or cyclin D3 mRNA in MM and MGUS is distinctly higher than in normal PCs, comparable with the levels of cyclin D2 mRNA expressed in normal proliferating PBs (Figure 1). Normal hematopoietic cells, including normal B lymphocytes, PCs, and PBs, express cyclin D2 and/or D3, but little or no cyclin D1.30Ā  Given the lack of cyclin D1 expression in normal lymphocytes, the occurrence of Ig translocations that dysregulate cyclin D1 or cyclin D3 in about 20% of MM tumors, the expression of cyclin D1 in nearly 40% of tumors lacking a t(11;14) translocation, and the increased expression levels of cyclin D2 in most remaining tumors, it seems apparent that almost all MM tumors dysregulate at least one of the cyclin D genes.

Figure 1.

Cyclin D expression in normal and malignant plasma cells. The raw scores for each of the 3 D-cyclins (D1, green bars; D2, red bars; D3, blue bars) from the Affymetrix HuFL dataset published by Tarte et al28Ā  and Zhan et al29Ā  are plotted one above the other. The samples are divided into 9 groups, and arranged by the level of expression of the predominant cyclin D within each group. The samples are CD138+ selected cells from 6 peripheral blood generated plasmablasts and 1 reactive plasmacytosis (PPC), 31 bone marrow PCs (BMPC) from healthy volunteers, and 78 samples from patients with newly diagnosed MM and 3 with plasma cell leukemia. Among these there are 2 with high CCND3 (6p21) and 15 with high CCND1 (11q13) (TC1); 25 with lower levels of CCND1 without t(11;14) (TC2); 4 with lower levels of D1 and elevated CCND2 (D1 + D2), 17 remaining patients with elevated CCND2 (other), and 2 patients without an elevated cyclin D (TC3); 9 with elevated FGFR3 (4p16) (TC4); and 7 with elevated CX3CR1 and Ī²7 integrin, a marker of maf dysregulation (maf, 16q23 and 20q11) (TC5).

Figure 1.

Cyclin D expression in normal and malignant plasma cells. The raw scores for each of the 3 D-cyclins (D1, green bars; D2, red bars; D3, blue bars) from the Affymetrix HuFL dataset published by Tarte et al28Ā  and Zhan et al29Ā  are plotted one above the other. The samples are divided into 9 groups, and arranged by the level of expression of the predominant cyclin D within each group. The samples are CD138+ selected cells from 6 peripheral blood generated plasmablasts and 1 reactive plasmacytosis (PPC), 31 bone marrow PCs (BMPC) from healthy volunteers, and 78 samples from patients with newly diagnosed MM and 3 with plasma cell leukemia. Among these there are 2 with high CCND3 (6p21) and 15 with high CCND1 (11q13) (TC1); 25 with lower levels of CCND1 without t(11;14) (TC2); 4 with lower levels of D1 and elevated CCND2 (D1 + D2), 17 remaining patients with elevated CCND2 (other), and 2 patients without an elevated cyclin D (TC3); 9 with elevated FGFR3 (4p16) (TC4); and 7 with elevated CX3CR1 and Ī²7 integrin, a marker of maf dysregulation (maf, 16q23 and 20q11) (TC5).

Close modal

Based on the results summarized, a model for the molecular pathogenesis of MM has been proposed.8Ā  Chromosome content appears to identify 2 differentā€”but perhaps overlappingā€” pathways of pathogenesis: nonhyperdiploid tumors with a very high incidence of IgH translocations involving the 5 recurrent partners and a relatively high incidence of chromosome 13/13q14 loss; and hyperdiploid tumors associated with multiple trisomies involving chromosomes 3, 5, 7, 9, 11, 15, 19, and 21, but a low incidence of both chromosome 13/13q14 loss and IgH translocations involving the 5 recurrent partners31-33Ā  (Figure 2). In about half of tumors, a primary chromosome translocation results in the dysregulated expression of an oncogene. This may lead directly (11q13-cyclin D1 and 6p21-cyclin D3) or indirectly (4p16, 16q23, other cyclin D2) to cyclin D dysregulation. Alternatively, the remaining tumors are mostly hyperdiploid, and cyclin D1 (or less often cyclin D2) usually is dysregulated by an undefined mechanism.27Ā  The dysregulation of 1 of 3 cyclin D genes may render the cells more susceptible to proliferative stimuli, resulting in selective expansion as a result of interaction with bone marrow stromal cells (BMSCs) that produce interleukin-6 (IL-6) and other cytokines. Karyotypic abnormalities, most notably IgH translocations, trisomies of chromosomes 3, 5, 7, 9, 11, 15, 19, and 21, and monosomy of chromosome 13 or 13q14 deletion, often are present in premalignant MGUS, the earliest identified stage of tumorigenesis.12,14Ā  Even though dysregulation of a cyclin D gene appears to be a nearly universal event in early pathogenesis, there is evidence that the retinoblastoma (Rb) pathway is further disrupted by p16INK4a methylation and inactivation in a substantial fraction of MGUS and MM tumors.34,35Ā  Tumor progression is associated with secondary chromosome translocations, of which c-myc provides a paradigm.8,26Ā  Mutually exclusive activating mutations of K- or N-Ras (or FGFR3 when there is a t(4;14) translocation) are rare or absent in MGUS, whereas Ras mutations are present in 30% to 40% of early MM, and FGFR3 mutations occur more frequently in advanced MM.21,36-38Ā  Mutations and/or monoallelic deletion of p53 occur frequently but only late in the course of the disease.39Ā  Further disruption of the Rb pathway by inactivation of Rb or p18INK4c can also occur at a low frequency, most likely as a late progression event.40,41Ā  The frequency and timing of other events, such as inactivation of phosphatase and tensin homolog (PTEN), remain to be determined.42,43Ā 

Figure 2.

Two pathways for progression to plasma cell neoplasia. Defined stages of pathogenesis are depicted, with shaded triangles indicating the possible timing and frequency of known oncogenic events. The earliest changes include 2 partially overlapping pathways, indicated by primary IgH translocations (tx) and multiple trisomies. Deletion 13 (most often in nonhyperdiploid tumors) and p16 methylation might be included among the earliest changes, but might sometimes be involved in progression. Activating mutations of N- and K-RAS appear to mark, if not cause, the MGUS to MM transition in some tumors, but can also occur as later progression events. Late oncogenic changes include inactivation of p18 and p53, and also translocations that dysregulate c-myc. Inactivation of Rb, PTEN, and secondary translocations not involving c-myc are not depicted.

Figure 2.

Two pathways for progression to plasma cell neoplasia. Defined stages of pathogenesis are depicted, with shaded triangles indicating the possible timing and frequency of known oncogenic events. The earliest changes include 2 partially overlapping pathways, indicated by primary IgH translocations (tx) and multiple trisomies. Deletion 13 (most often in nonhyperdiploid tumors) and p16 methylation might be included among the earliest changes, but might sometimes be involved in progression. Activating mutations of N- and K-RAS appear to mark, if not cause, the MGUS to MM transition in some tumors, but can also occur as later progression events. Late oncogenic changes include inactivation of p18 and p53, and also translocations that dysregulate c-myc. Inactivation of Rb, PTEN, and secondary translocations not involving c-myc are not depicted.

Close modal

In addition to determining the expression level of cyclin D1, D2, and D3, gene expression profiling can effectively identify MM tumors that overexpress the oncogenes dysregulated by the 5 recurrent IgH translocations: 11q13 (cyclin D1); 6p21 (cyclin D3); 4p16 (MMSET and usually FGFR3); 16q23 (c-maf); and 20q11 (mafB).27,29Ā  We propose 5 translocation and cyclin D (TC) groups (Table 1) that can be distinguished based on the 5 recurrent Ig translocations and cyclin D expression: TC1 tumors (18%) express high levels of either cyclin D1 or cyclin D3 as a result of an Ig translocation; TC2 tumors (37%) ectopically express low to moderate levels of cyclin D1 despite the absence of a t(11;14) translocation; TC3 tumors (22%) are a mixture of tumors that do not fall into one of the other groups, with most expressing cyclin D2, but a few also expressing low levels of cyclin D1 or cyclin D3; TC4 tumors (16%) express high levels of cyclin D2, and also MMSET (and in most cases FGFR3) as a result of a t(4;14) translocation; and TC5 tumors (7%) express the highest levels of cyclin D2, and also high levels of either c-maf or mafB, consistent with evidence that both maf transcription factors up-regulate the expression of cyclin D2.44Ā 

In addition to tumor mass and secondary features that represent a host response to MM (anemia, thrombocytopenia, bone disease, immunodeficiency, etc), intrinsic properties of the tumor cell are also informative in predicting prognosis and response to existing therapies. For example, it has been well documented that an unfavorable outcome is associated with each of the following: increased plasma cell labeling index, the generation of tumor cells with an abnormal karyotype (perhaps a surrogate for increased proliferation), hypodiploidy compared with hyperdiploidy, monosomy of chromosome 13/13q, monosomy of chromosome 17/deletion of p53, and lack of cyclin D1 expression.7,13,31-33,45,46Ā  It also has been reported and independently confirmed that activating mutations of K-Ras (but not N-Ras) represent an adverse prognostic factor.37,38Ā  More recently, it has become clear that specific IgH translocations also have a profound prognostic significance13,24Ā  (Table 1). In particular, patients with tumors that have a t(4;14) translocation (TC4) have a substantially shortened survival either with standard or high-dose therapy (median overall survival [OS], 26 months and 33 months, respectively), and patients with a t(14;16) (TC5) have a similarly poor if not worse prognosis (median OS, 16 months with conventional therapy). By contrast, patients with tumors that have a t(11;14) translocation (TC1) appear to have a marginally better survival following conventional chemotherapy (median OS, 50 months), but apparently a remarkably better survival following intense therapy (predicted 88% OS at 80 months). These results suggest that the TC classification, which appears to be based on the earliest events in pathogenesis, may be a clinically useful way to classify patients into groups that have distinct subtypes of MM (and MGUS) tumors.13,47-49Ā  The TC classification identifies clinically important molecular subtypes of MM with different prognoses and with unique responses to different treatments (eg, high dose therapy [HDT] and TC1, microenvironment-directed therapy and TC2, FGFR3 inhibitor and TC4, maf dominant-negative and TC5).

The critical role of cyclin D dysregulation in the pathogenesis of MM highlights the importance of the cyclin D/Rb pathway and suggests that there may be a therapeutic window in targeting this pathway50Ā  for all molecular subtypes of MM (Figure 3). For example, epigenetic silencing of cyclin-dependent kinase (CDK) inhibitor mRNA expression might be reversed by histone deacetylase (HDAC) inhibitors (suberoylanilide hydroxamic acid [SAHA], depsipeptide) or inhibitors of DNA methyl transferase (5 aza-2ā€²deoxy-cytidine).51Ā  To target cyclin D, per se, there are a number of possible strategies including modulation of mRNA translation (eg, desferroxamine, eicosapentaenoic acid),52,53Ā  posttranslational modifications (ubiquitination and proteasomal degradation),54,55Ā  enzyme function (selective CDK kinase inhibitors),50,56Ā  and perhaps even inhibition of expression of cyclin D mRNA (the TC2 group may be particularly dependent on interaction with BM stromal cells for the ectopic expression of cyclin D1). Additional specificity may be achieved by targeting the genes directly dysregulated by translocations. This seems to be especially true in the case of the t(4;14) where 2 enzymes are overexpressed: FGFR3, a tyrosine kinase receptor, and MMSET, which has homology to histone methyltransferases. As a surface receptor, FGFR3 may be targeted by monoclonal antibodies, and as a tyrosine kinase, by selective tyrosine kinase inhibitors. Preclinical studies have validated FGFR3 as a therapeutic target in t(4;14) MM,57Ā  inhibitors of histone methyltransferases are being developed, and studies are under way to validate MMSET as a target in t(4;14) MM.

Figure 3.

Critical role for cyclin D/Rb pathway in multiple myeloma. The 5 TC molecular subtypes of myeloma are characterized by either direct (solid arrow) or indirect (dashed arrow) dysregulation of a D cyclin. Cyclin D together with CDK4 and 6 is involved in G1-S cell cycle progression by phosphorylating and inactivating Rb. This reaction is inhibited by the CDK inhibitors INK4a-d. In addition to cyclin D, other members that are targeted by genetic mutation in MM are highlighted (p16 by methylation, p18 by small homozygous deletions, and Rb by monoallelelic deletion).

Figure 3.

Critical role for cyclin D/Rb pathway in multiple myeloma. The 5 TC molecular subtypes of myeloma are characterized by either direct (solid arrow) or indirect (dashed arrow) dysregulation of a D cyclin. Cyclin D together with CDK4 and 6 is involved in G1-S cell cycle progression by phosphorylating and inactivating Rb. This reaction is inhibited by the CDK inhibitors INK4a-d. In addition to cyclin D, other members that are targeted by genetic mutation in MM are highlighted (p16 by methylation, p18 by small homozygous deletions, and Rb by monoallelelic deletion).

Close modal

Similar to their normal BM plasma cell (BMPC) counterpart, MGUS and MM tumors are dependent on mutual interactions with cells and extracellular components of the BM for survival and growth. Exceptions to this include primary plasma cell leukemia (PCL) and terminal phases of MM, which sometimes extend to extramedullary sites. Significantly, virtually all HMCLs are derived from PCL or extramedullary tumor. Although not yet well understood, there is increasing evidence that some of the earliest oncogenic events differentially affect the interaction of tumor cells with BM components. First, tumors in the TC1 and TC2 groups are more strongly associated with lytic bone lesions than tumors in the TC4 and TC5 groups (P.L.B., unpublished observations, January 2004).58Ā  Second, the maf transcription factorā€“stimulated expression of Ī²7 integrin and other surface receptors or cytokines seems likely to influence the interactions of the TC5 tumor group in the BM.44Ā  Third, in contrast to tumors in the other TC groups, TC2 tumors (hyperdiploid with multiple trisomies and cyclin D1 expression without a t(11;14)) are greatly underrepresented or absent in primary PCL59Ā  and HMCLs.27Ā  Thus TC2 tumors may be uniquely dependent on the BM environment, with the possibility that the ectopic/increased expression of cyclin D1 is dependent on the BM microenvironment. For example, IL-6 secreted by BMSCs triggers phosphorylation of Akt and downstream glycogen synthase kinase 3Ī² (GSK-3Ī²).60Ā  GSK-3Ī² in turn induces phosphorylation of cyclin D1 followed by degradation through the ubiquitin-proteasome pathway, thereby promoting the transition from G1 to S phase.61Ā  Tumor necrosis factor Ī± (TNFĪ±) in the BM milieu activates nuclear factor ĪŗB (NF-ĪŗB), thereby modulating expression of adhesion molecules on both MM cells and BMSCs, as well as inducing IL-6 transcription and secretion in BMSCs. Activated NF-ĪŗB also binds to the promoter of cyclin D1, thereby regulating its expression.62,63Ā 

MM cells home to the BM and adhere to extracellular matrix (ECM) proteins and to BM stromal cells (BMSCs), which not only localizes tumor cells in the BM milieu but also has important functional sequelae.64Ā  Specifically, adhesion of MM cells to ECM proteins confers cell adhesionā€“mediated drug resistance (CAM-DR),65-67Ā  and binding of MM cells to BMSCs triggers transcription and secretion of cytokines (ie, IL-6, insulin-like growth factor 1 [IGF-1], or vascular endothelial growth factor [VEGF]) from BMSCs, which not only promotes growth, survival, and migration of MM cells but also further confers resistance to conventional chemotherapy.60,68-72Ā  Delineation of mechanisms mediating MM cell growth, survival, and drug resistance in the BM milieu provides the framework to develop and validate novel anti-MM agents to overcome drug resistance and improve patient outcome.73Ā 

Adhesion molecules mediate both homotypic and heterotypic adhesion of MM cells to either ECM proteins or BMSCs.64Ā  Adhesion molecules CD44, very late antigen 4 (VLA-4), VLA-5, leukocyte function-associated antigen-1 (LFA-1, CD11a), CD56 (neural cell adhesion molecule), CD54 (intercellular adhesion molecule-1 [ICAM-1]), syndecan-1 (CD138), and MPC-1 mediate homing of MM cells to the BM. Subsequently, tumor cells binds to ECM proteins (ie, via syndecan-1 and VLA-4 on MM cells to type I collagen and fibronectin, respectively) and to BMSCs (ie, via VLA-4 on MM cells to vascular cell adhesion molecule 1 [VCAM-1, CD106] on BMSCs; Figure 4). Binding not only localizes tumor cells in the BM microenvironment, but also has important functional and clinical sequelae. Syndecan-1 regulates tumor cell growth and survival, and elevated serum levels correlate with increased tumor cell mass, decreased metalloproteinase-9 activity, and poor prognosis.74,75Ā  Furthermore, adhesion of MM cells via syndecan-1 to collagen induces matrix metalloproteinase-1, thereby promoting bone resorption and tumor invasion. Importantly, binding via VLA-4 on MM cells to the ECM protein fibronectin triggers up-regulation of p27Kip1 and other genetic changes that confer CAM-DR.65-67Ā  Adhesion of MM cells to BMSCs triggers nuclear factor ĪŗB (NF-ĪŗB)ā€“dependent transcription and secretion of IL-6,76Ā  whereas inhibition of NF-ĪŗB activity abrogates this response.77,78Ā  Moreover, MM cells localized in the BM milieu secrete cytokines such as TNFĪ±,79Ā  transforming growth factor Ī² (TGF-Ī²),80Ā  and VEGF,81Ā  which further up-regulate IL-6 secretion from BMSCs. Most importantly, within the BM microenvironment these cytokines mediate growth (IL-6, IGF-1, VEGF), survival (IL-6, IGF-1), drug resistance (IL-6, IGF-1, VEGF), and migration (IGF-1, VEGF, SDF-1Ī±) of MM cells, and also trigger angiogenesis (VEGF) (Figure 4). Novel agents that can overcome CAM-DR and the growth advantage conferred in the BM in vitro, including thalidomide, immunomodulatory drugs (IMiDs), and proteasome inhibitors, hold great promise to overcome conventional drug resistance and improve patient outcome.73Ā 

Figure 4.

Interaction of MM cells and their BM milieu. Binding of MM cells to BMSCs triggers both adhesion- and cytokine-mediated MM cell growth, survival, drug resistance, and migration. MM cell binding to BMSCs up-regulates cytokine (IL-6, IGF-1, VEGF, SDF-1Ī±) secretion from both BMSCs and MM cells. These cytokines subsequently activate 3 major signaling pathways (ERK, JAK/STAT3, and/or PI3-K/Akt), and their downstream targets including cytokines (IL-6, IGF-1, VEGF) and antiapoptotic proteins (Bcl-xL, IAPs, Mcl-1) in MM cells. Adhesion-mediated activation of NF-ĪŗB up-regulates adhesion molecules (ICAM-1, VCAM-1) on both MM cells and BMSCs, further enhancing adhesion of MM cells to BMSCs.

Figure 4.

Interaction of MM cells and their BM milieu. Binding of MM cells to BMSCs triggers both adhesion- and cytokine-mediated MM cell growth, survival, drug resistance, and migration. MM cell binding to BMSCs up-regulates cytokine (IL-6, IGF-1, VEGF, SDF-1Ī±) secretion from both BMSCs and MM cells. These cytokines subsequently activate 3 major signaling pathways (ERK, JAK/STAT3, and/or PI3-K/Akt), and their downstream targets including cytokines (IL-6, IGF-1, VEGF) and antiapoptotic proteins (Bcl-xL, IAPs, Mcl-1) in MM cells. Adhesion-mediated activation of NF-ĪŗB up-regulates adhesion molecules (ICAM-1, VCAM-1) on both MM cells and BMSCs, further enhancing adhesion of MM cells to BMSCs.

Close modal

Since adhesion molecules play a central role in the pathogenesis of MM, therapeutic strategies targeting these molecules and the sequelae of adhesion have been developed and tested in animal models (ie, antiā€“ICAM-1 antibodies inhibit tumor development in severe combined immunodeficient [SCID] mice). In addition, SCID mice bearing human fetal bone grafts (SCID-hu mice) have been used to study in vivo homing and binding of human MM cells to human ECM proteins and BMSCs; related induction of human cytokines; associated tumor cell growth, survival, drug resistance, and migration; as well as evaluation of novel therapeutics.82-84Ā  This model allows for direct evaluation of the impact of the human BM microenvironment and cytokines on tumor cell pathogenesis. Most recently, we have used green fluorescent protein (GFP)ā€“labeled MM cells within a similar SCID mouse model to demonstrate that binding of MM cells in BM induces genes in tumor cells conferring growth, survival, drug resistance, and migration as well as genes in BMSCs modulating cytokines.85Ā  This model allows for whole body imaging to assess tumor migration and localization in vivo. Moreover, evaluation of novel therapies in this model has identified agents (ie, IGF-1 and heat shock protein [Hsp] 90 inhibitors)86,87Ā  with great promise to overcome drug resistance and improve patient outcome. One drawback of this model is the study of human MM cells in murine BM, given the lack of cross-reactivity of some murine cytokines with human tumor cells.

IL-6

Although some MM cells secrete IL-6 and grow in an autocrine fashion,88Ā  it is primarily produced in BMSCs89,90Ā  and mediates paracrine MM cell growth. Its secretion is up-regulated in MM cells by CD40 activation91Ā  and in BMSCs by either adhesion of MM cells or cytokines (TNFĪ±, VEGF, IL-1Ī²).79,81,92Ā  Binding of MM cells to BMSCs induces NF-ĪŗB activation and related up-regulation of IL-6 transcription and secretion in BMSCs; conversely, specific inhibition of NF-ĪŗB by IĪŗB kinase (IKK) inhibitor down-regulates both constitutive and induced IL-6 secretion.78Ā  CD45+ MM cells have recently been identified as those MM cells responsive to IL-6.93,94Ā 

IL-6 binds to gp80 (CD80, IL-6R) expressed on most MM cell lines and patient tumor cells, thereby inducing phosphorylation and homodimerization of gp130.95-98Ā  Phosphorylation of gp130 in turn activates Ras/Raf/mitogen-activated protein kinase (MAPK) kinase (MEK)/extracellular signal-related kinase (ERK), Janus kinase (JAK)/signal transducer and activator of transcription (STAT), and phosphatidylinositol-3 kinase (PI3-K)/Akt (PKB) downstream signaling pathways in MM cells (Figure 4) mediating MM cell growth, survival, and drug resistance, respectively.60,71,99-104Ā  Targeted inhibition of Ras/Raf/MEK/ERK signaling using farnesyl-transferase inhibitor (R115777),102,103Ā  ERK antisense oligonucleotide, and MEK1 inhibitor PD98059,100Ā  or MEK1/2 inhibitor U0126,104Ā  abrogates tumor cell growth. Survival and drug resistance of MM cells are mediated via activation of both JAK2/STAT3 and PI3-K/Akt signaling cascades. STAT3 regulates downstream protein expression of Bcl-2 family members Bcl-xL101Ā  and Mcl-1,105-107Ā  and expression of these antiapoptotic proteins can be selectively down-regulated by dominant/negative STAT3 or JAK inhibitor101,108,109Ā  and antisense Mcl-1.110Ā  Moreover, cyclin-dependent kinase inhibitor flavopiridol induces apoptosis in MM cells, at least in part, by down-regulating Mcl-1.111Ā  IL-6 confers resistance to dexamethasone (Dex),68,69,112Ā  a common conventional therapy, via PI3-K/Akt signaling.60Ā  Dex-mediated apoptosis in MM cells is associated with downstream release of second mitochondria activator of caspase (Smac), but not of cytochrome-c (cyto-c),113Ā  from mitochondria114Ā ; cytosolic Smac disrupts X-linked inhibitor of apoptosis protein (XIAP)/caspase-9 complexes, thereby allowing activation of caspase-9, caspase-3 cleavage, and apoptosis. Since caspase-9 is a downstream target of Akt,115,116Ā  IL-6 protects against Dex-induced apoptosis via inactivation of caspase-960Ā ; conversely, PI3-K inhibitors block IL-6ā€“mediated protection against Dex-induced apoptosis.60,71Ā  Recent studies show that X-box binding protein 1 (XBP-1), a transcription factor that induces differentiation of normal B cells to plasma cells, is induced by IL-6 in patient MM cells117-119Ā ; proteasome inhibitors act against MM cells, at least in part, by targeting XBP-1 and the unfolded protein response.120Ā  Finally, it has shown that IL-6 induces caveolin-1 phosphorylation on the MM cell surface, whereas inhibition of caveolin-1 function blocks IL-6ā€“mediated signaling and growth in MM cells.121Ā 

Clinically, serum IL-6 and IL-6 receptors (IL-6Rs) are prognostic factors in MM reflective of the proliferative fraction of tumor cells.122-124Ā  Treatment strategies targeting IL-6 to date include antibodies to IL-6 and IL-6 receptor, as well as IL-6 superantagonists that compete for IL-6R binding but do not activate downstream signaling125-129Ā ; to date, however, only transient responses have been observed.

IGF-1

IGF-1 induces proliferation, survival, and drug resistance in MM cells via MEK/ERK and PI3-K/Akt signaling cascades. Although IGF-1 does not induce JAK2/STAT3 signaling in MM cells, it is a more potent inducer of Akt signaling than IL-6 and confers protection against Dex.71,130-132Ā  IGF-1 triggers phosphorylation of FKHR (forkhead transcription factor); up-regulates intracellular antiapoptotic proteins including FLICE-inhibitory protein, survivin, cellular inhibitor of apoptosis protein 2, A1/Bfl-1, and XIAP132Ā ; and increases telomerase activity via induction of PI3-K/Akt/NF-ĪŗB signaling133Ā  (Figure 4). Inhibitors of IGF-1 receptor demonstrate promising anti-MM activity in preclinical studies72Ā ; PI3-K or IKK inhibitors also block IGF-1ā€“induced telomerase activity.133,134Ā 

VEGF

VEGF is produced in MM cells and BMSCs and accounts, at least in part, for increased angiogenesis in MM patient BM.135,136Ā  Furthermore, both adhesion of MM cells to BMSCs and exogenous IL-6 up-regulate VEGF secretion, as does CD40 activation of human MM cells81,92,137Ā  (Figure 4). VEGF triggers Flt-1 phosphorylation and activation of MEK/ERK and PI-3K/PKCĪ± signaling cascades in MM cell lines and patient cells, thereby promoting modest proliferation and pronounced migration, respectively.138,139Ā  These direct effects of VEGF on MM cells and BM angiogenesis suggest potential use of novel therapies targeting VEGF; already VEGF receptor tyrosine kinase inhibitor PTK787 has demonstrated promise in preclinical studies.140,141Ā 

TNFĪ± and CD40 ligand

Both patient MM cells and BM mononuclear cells (BMMCs) express TNFĪ± mRNA and protein,142-144Ā  and TNFĪ± secretion is significantly higher in those MM patients with bone disease.145Ā  It induces tumor cell apoptosis via Fas-associated death domain/caspase-8 signaling,146,147Ā  as well as survival via NF-ĪŗB activation and up-regulation of antiapoptotic proteins (ie, Bcl-xL, XIAP, inhibitor of apoptosis protein [IAP])148-151Ā  (Figure 4). Combining TNFĪ± inhibition with NF-ĪŗB blockade using IKK inhibitors enhances cytotoxicity.78Ā  Although TNFĪ± secreted by MM cells does not induce growth, survival, or drug resistance in tumor cells, it binds to a TNFĪ± response element in the IL-6 promoter in BMSCs, and more potently triggers paracrine IL-6 transcription and secretion than does either VEGF or TGF-Ī².79Ā  Moreover, TNFĪ± secreted by MM cells induces NF-ĪŗBā€“dependent up-regulation of adhesion molecules on both MM and BMSCs (CD49d, CD54),79Ā  thereby increasing the binding of MM to BMSCs with associated CAM-DR and induction of cytokine (IL-6, IGF-1, VEGF) secretion in BMSCs.76,78,79Ā  Novel agents targeting TNFĪ±, including thalidomide and the IMiDs,152Ā  act against MM, at least in part, by inhibiting sequelae of these induced cytokines.

CD40 ligand, a TNFĪ± family member, modulates MM cell growth both directly and indirectly via its actions in the BM milieu.91,153,154Ā  Specifically, activation of MM cells via CD40 directly triggers p53-dependent growth versus apoptosis, as well as PI3/Akt NF-ĪŗBā€“dependent MM cell migration.155Ā  CD40 ligation also induces VEGF secretion in BMSCs, which mediates MM cell homing and migration as well as angiogenesis in the BM milieu.137Ā  Finally, CD40 activation up-regulates both HLA and costimulatory molecules on MM cells, thereby augmenting their antigenpresenting capacity.

Other cytokines

Stromal cellā€“derived factor 1 Ī± (SDF-1Ī±), the ligand for chemokine receptor CXCR4, is present in supernatants from MM patient BMSCs, whereas CXCR4 is expressed on MM cells.156Ā  SDF-1Ī± transiently up-regulates VLA-4ā€“mediated MM cell adhesion in the BM milieu,157Ā  as well as inducing modest proliferation, migration, and protection against Dex-induced apoptosis via activation of ERK, PI3-K/Akt, and NF-ĪŗB signaling cascades, respectively.156Ā  SDF-1Ī± also induces secretion of IL-6 and VEGF in BMSCs, thereby further promoting MM cell growth, survival, drug resistance, and migration (Figure 4). Transforming growth factor beta (TGF-Ī²) secreted by MM cells triggers paracrine IL-6 secretion in BMSCs91Ā ; conversely, TGF-Ī² receptor inhibitors down-regulate IL-6 secretion in BMSCs and associated paracrine MM cell growth.158Ā  IL-21 induces DNA synthesis in patient MM cells via phosphorylation of JAK1, STAT3, and ERK.159Ā  B-cell stimulation factor 3 (BSF-3) triggers ERK and STAT3 phosphorylation, thereby stimulating growth and conferring Dex resistance in MM cells.160Ā  IL-1, IL-6, receptor activator of NF-ĪŗB ligand (RANKL), parathyroid hormone-related protein (PTHrP), and macrophage inflammatory protein 1-Ī± (MIP-1Ī±) mediate bone destruction via activation of osteoclasts. RANKL triggers osteoclastogenesis and bone resorption as well as enhancing induction of osteoclasts by MIP-1Ī± and/or IL-6.161-164Ā  Most recently, increased Dickkopf 1 (DKK1) expression has been reported in MM cells, implicating Wnt signaling in suppression of osteoblasts and lytic lesions of bone in MM.58Ā 

Both conventional and novel chemotherapeutic agents target specific kinases mediating MM cell growth, survival, and apoptosis.73Ā  Most agents trigger apoptosis, which can be distinguished from necrosis by the lack of an associated inflammatory response.165Ā  Cytosolic aspartateā€“specific proteases (CASPases), which disassemble cells into apoptotic bodies, are present as inactive proenzymes and commonly activated by proteolytic cleavage.166Ā  In MM cells, caspase-8 is activated in response to extracellular apoptosis-inducing ligand (ie, TNFĪ±, TRAIL), by cytoplasmic death domain (ie, Fas-associated death domain [FADD]),167Ā  and by novel agents such as the immunomodulatory drug CC-5013 (lenalidomide, also known as Revimid or Revlimid)168Ā  (Figure 5). On the other hand, caspase-9 is activated in response to agents that trigger release of cyto-c from mitochondria to the cytosol. Importantly, Dex-induced apoptosis in MM cells is associated with caspase-9 activation and release of second mitochondria-derived activator of caspases (Smac), but not cyto-c.114Ā  Activation of either caspase-8 or caspase-9 is followed by downstream activation of caspase-3, poly adenosine diphosphateā€“ribose polymerase (PARP), and DNA fragmentation factor (DFF). Cross-talk of apoptotic signaling from caspase-8 to caspase-9 can occur (ie, via Bid).169,170Ā  Furthermore, novel proteasome inhibitor bortezomib (Velcade), 2-methoxyestradiol (2ME2), and lysophosphatidic acid acyltransferase-Ī² (LPAAT-Ī²) inhibitors activate c-Jun NH2-terminal kinase (JNK), which translocates from cytosol to mitochondria, thereby facilitating release of mitochondrial cyto-c/Smac to the cytosol and sequential activation of caspases-9 and -3; conversely, blocking JNK using either specific JNK inhibitor SP600125 or dominant-negative JNK abrogates both stress-induced release of cyto-c/Smac and induction of apoptosis171-173Ā  (Figure 5).

Figure 5.

Apoptotic signaling pathways triggered by conventional and novel therapies. Fas/FasL, TRAIL, Thal/IMiDs, and HDAC inhibitors trigger activation of caspase-8, whereas Dex activates caspase-9. Bortezomib (Velcade) and 2ME-2 induce both caspase-8 and -9 activation. Both IL-6 and IGF-1 inhibit caspase-9/caspase-3 apoptotic signaling via activation of Akt signaling.

Figure 5.

Apoptotic signaling pathways triggered by conventional and novel therapies. Fas/FasL, TRAIL, Thal/IMiDs, and HDAC inhibitors trigger activation of caspase-8, whereas Dex activates caspase-9. Bortezomib (Velcade) and 2ME-2 induce both caspase-8 and -9 activation. Both IL-6 and IGF-1 inhibit caspase-9/caspase-3 apoptotic signaling via activation of Akt signaling.

Close modal

Apoptosis can also be triggered or enhanced by down-regulation of inhibitor of apoptosis protein (IAP) activity (ie, inhibition of NF-ĪŗB activity down-regulates IAPs and enhances MM sensitivity to various drugs).168Ā  Bcl-2 family proteins regulate the release of cyto-c from mitochondria to cytosol; inhibition of these proteins (ie, Bcl-2, Bcl-xL, Mcl-1) therefore also enhances sensitivity of MM cells to apoptotic stimuli.110,174Ā  Importantly, these preclinical studies delineating apoptotic signaling induced by conventional and novel agents provide the framework for clinical treatment protocols. For example, both TRAIL and Revimid trigger caspase-8ā€“mediated MM cell death168Ā  and enhanced killing via intrinsic signaling in vitro, suggesting their potential combined clinical use (Figure 5). On the other hand, bortezomib induces predominantly activation of caspase-8, whereas Dex triggers activation of capase-9, providing the preclinical framework for combining agents in clinical protocols to induce dual apoptotic signaling. To date, thalidomide plus dexamethasone treatment has demonstrated significant antitumor activity against newly diagnosed175Ā  as well as relapsed refractory MM.176Ā  Bortezomib inhibits DNA repair by cleaving DNA-PKCs and ataxiatelangiectasia protein (ATM),171Ā  thereby enhancing cytotoxicity or overcoming resistance to DNA damaging agents in vitro.177Ā  Importantly, recent studies show that bortezomib can also overcome clinical resistance to doxorubicin and melphalan.178,179Ā 

Both in vitro systems and in vivo animal models to characterize mechanisms of MM cell homing to BM have been developed, including the factors (MM cellā€“BMSCs interactions, cytokines, angiogenesis) promoting MM cell growth, survival, drug resistance, and migration in the BM milieu73Ā  (Figure 6). These model systems have allowed for the development of several promising biologically based therapies that can target directly or indirectly both the MM cell and BM microenvironment including thalidomide/CC-5013 (Revimid),168,180-183Ā  PS-341 (bortezomib),77,171,184-186Ā  VEGF receptor kinase inhibitor PTK787,140Ā  HDAC inhibitors SAHA187Ā  and LAQ-824,188Ā  2-ME2,118,189Ā  arsenic trioxide,190Ā  and LPAAT-Ī² inhibitor173Ā ; those that target MM cells including telomestatin,191Ā  Hsp-90 inhibitor 17-AAG,87Ā  TRAIL,168,192Ā  statins,193Ā  IGF-1R inhibitor72Ā ; and those that target only the BM microenvironment including IĪŗB kinase inhibitors78Ā  and p38MAPK inhibitors194Ā  (Table 2). It is our hypothesis that drugs in these classes will need to be combined to achieve complete eradication of MM cells, and we are presently studying their mechanisms of action at a gene and protein level in order to provide the framework for rational combination clinical trials to overcome drug resistance and improve patient outcome.118Ā 

Figure 6.

Novel biologically based therapies targeting MM cells and the BM microenvironment. Novel agents (A) induce G1 growth arrest and/or apoptosis in MM cell lines and patient cells resistant to conventional chemotherapy; (B) inhibit MM cell adhesion to BMSCs; (C) decrease cytokine production and sequelae in the BM microenvironment; and (D) decrease angiogenesis.

Figure 6.

Novel biologically based therapies targeting MM cells and the BM microenvironment. Novel agents (A) induce G1 growth arrest and/or apoptosis in MM cell lines and patient cells resistant to conventional chemotherapy; (B) inhibit MM cell adhesion to BMSCs; (C) decrease cytokine production and sequelae in the BM microenvironment; and (D) decrease angiogenesis.

Close modal

Having demonstrated preclinical promise of these novel agents, we have rapidly translated our laboratory studies to phase 1, 2, and 3 clinical trials to evaluate their clinical use and toxicity, and to move them rapidly from the bench to the bedside. Most excitingly, bortezomib195Ā  and Revlimid196Ā  have already demonstrated marked clinical anti-MM activity even in patients with refractory relapsed MM, confirming the use of our preclinical models to identify and validate novel therapeutics. Importantly, gene array and proteomic studies have helped to identify in vivo mechanisms of action and drug resistance, as well as aiding in their clinical application. For example, gene microarray profiling of bortezomib-treated MM cells reveals induction of heat shock protein 90 stress response,171,184Ā  providing the rationale for the combined clinical use of bortezomib and 17-AAG to enhance anti-MM activity. The study of proteomics also forms the basis for clinical application. For example, protein profiling of bortezomib-treated MM cells demonstrated cleavage of DNA repair enzymes, providing the rationale for combining bortezomib with DNA damaging agents to enhance sensitivity or overcome resistance to these conventional therapies.177Ā  These studies have provided the framework for a new treatment paradigm targeting MM cell-host BMSC interactions and their sequelae in the BM milieu to overcome drug resistance and improve patient outcome in MM.

Recent studies have enabled the definition of molecular subtypes of MM and also the role of the BM milieu in pathogenesis. These studies have provided the framework for identification and validation of novel targeted therapies to overcome drug resistance and improve patient outcome. In the future, gene and protein profiling will enable patient-specific selection of targeted therapies197Ā  and will also provide the framework for development of more potent and less toxic targeted therapies.

Prepublished online as Blood First Edition Paper, April 15, 2004; DOI 10.1182/blood-2004-01-0037.

Supported by National Institutes of Health Grant Specialized Programs of Research Excellence (SPORE) IP50 CA10070-01, PO-1 78378, and RO-1 CA 50947; the Doris Duke Distinguished Clinical Research Scientist Award; the Multiple Myeloma Research Foundation; and the Cure for Myeloma Research Fund.

The publication costs of this article were defrayed in part by page charge payment. Therefore, and solely to indicate this fact, this article is hereby marked ā€œadvertisementā€ in accordance with 18 U.S.C. section 1734.

1
Ries LAG, Eisner MP, Kosary CL, et al, eds.
SEER Cancer Statistics Review, 1973-1999
. Bethesda, MD: National Cancer Institute;
2002
.
2
Kyle RA, Therneau TM, Rajkumar SV, et al. Prevalence of monoclonal gammopathy of undetermined significance (MGUS) among Olmsted County, MN residents over 50 years of age [abstract].
Blood
.
2003
;
102
:
3476a
.
3
Abraham RS, Geyer SM, Price-Troska TL, et al. Immunoglobulin light chain variable (V) region genes influence clinical presentation and outcome in light chain-associated amyloidosis (AL).
Blood
.
2003
;
101
:
3801
-3808.
4
Kyle RA, Therneau TM, Rajkumar SV, et al. A long-term study of prognosis in monoclonal gammopathy of undetermined significance.
N Engl J Med
.
2002
;
346
:
564
-569.
5
Cohen HJ, Crawford J, Rao MK, Pieper CF, Currie MS. Racial differences in the prevalence of monoclonal gammopathy in a community-based sample of the elderly.
Am J Med
.
1998
;
104
:
439
-444.
6
Lynch HT, Sanger WG, Pirruccello S, Quinn-Laquer B, Weisenburger DD. Familial multiple myeloma: a family study and review of the literature.
J Natl Cancer Inst
.
2001
;
93
:
1479
-1483.
7
Rajkumar SV, Fonseca R, Dewald GW, et al. Cytogenetic abnormalities correlate with the plasma cell labeling index and extent of bone marrow involvement in myeloma.
Cancer Genet Cytogenet
.
1999
;
113
:
73
-77.
8
Kuehl WM, Bergsagel PL. Multiple myeloma: evolving genetic events and host interactions.
Nat Rev Cancer
.
2002
;
2
:
175
-187.
9
Bergsagel PL, Kuehl WM. Chromosome translocations in multiple myeloma.
Oncogene
.
2001
;
20
:
5611
-5622.
10
Ahmann GJ, Jalal SM, Juneau AL, et al. A novel three-color, clone-specific fluorescence in situ hybridization procedure for monoclonal gammopathies.
Cancer Genet Cytogenet
.
1998
;
101
:
7
-11.
11
Avet-Loiseau H, Facon T, Daviet A, et al. 14q32 translocations and monosomy 13 observed in monoclonal gammopathy of undetermined significance delineate a multistep process for the oncogenesis of multiple myeloma. Intergroupe Francophone du Myelome.
Cancer Res
.
1999
;
59
:
4546
-4550.
12
Avet-Loiseau H, Facon T, Grosbois B, et al. Oncogenesis of multiple myeloma: 14q32 and 13q chromosomal abnormalities are not randomly distributed, but correlate with natural history, immunological features, and clinical presentation.
Blood
.
2002
;
99
:
2185
-2191.
13
Fonseca R, Blood E, Rue M, et al. Clinical and biologic implications of recurrent genomic aberrations in myeloma.
Blood
.
2003
;
101
:
4569
-4575.
14
Fonseca R, Bailey RJ, Ahmann GJ, et al. Genomic abnormalities in monoclonal gammopathy of undetermined significance.
Blood
.
2002
;
100
:
1417
-1424.
15
Anderson KC, Shaughnessy JD Jr, Barlogie B, Harousseau JL, Roodman GD. Multiple myeloma.
Hematology (Am Soc Hematol Educ Program)
.
2002
:
214
-240.
16
Fonseca R, Harrington D, Oken MM, et al. Biological and prognostic significance of interphase fluorescence in situ hybridization detection of chromosome 13 abnormalities (delta13) in multiple myeloma: an Eastern Cooperative Oncology Group study.
Cancer Res
.
2002
;
62
:
715
-720.
17
Sawyer JR, Lukacs JL, Munshi N, et al. Identification of new nonrandom translocations in multiple myeloma with multicolor spectral karyotyping.
Blood
.
1998
;
92
:
4269
-4278.
18
Sawyer JR, Lukacs JL, Thomas EL, et al. Multicolour spectral karyotyping identifies new translocations and a recurring pathway for chromosome loss in multiple myeloma.
Br J Haematol
.
2001
;
112
:
167
-174.
19
Chesi M, Nardini E, Brents LA, et al. Frequent translocation t(4;14)(p16.3;q32.3) in multiple myeloma: association with increased expression and activating mutations of fibroblast growth factor receptor 3.
Nat Genetics
.
1997
;
16
:
260
-264.
20
Chesi M, Nardini E, Lim RSC, Smith KD, Kuehl WM, Bergsagel PL. The t(4;14) translocation in myeloma dysregulates both FGFR3 and a novel gene, MMSET, resulting in IgH/MMSET hybrid transcripts.
Blood
.
1998
;
92
:
3025
-3034.
21
Chesi M, Bergsagel PL, Kuehl WM. The enigma of ectopic expression of FGFR3 in multiple myeloma: a critical initiating event or just a target for mutational activation during tumor progression.
Curr Opin Hematol
.
2002
;
9
:
288
-293.
22
Keats JJ, Reiman T, Maxwell CA, et al. In multiple myeloma, t(4;14)(p16;q32) is an adverse prognostic factor irrespective of FGFR3 expression.
Blood
.
2003
;
101
:
1520
-1529.
23
Santra M, Zhan F, Tian E, Barlogie B, Shaughnessy J Jr. A subset of multiple myeloma harboring the t(4;14)(p16;q32) translocation lacks FGFR3 expression but maintains an IGH/MMSET fusion transcript.
Blood
.
2003
;
101
:
2374
-2376.
24
Moreau P, Facon T, Leleu X, et al. Recurrent 14q32 translocations determine the prognosis of multiple myeloma, especially in patients receiving intensive chemotherapy.
Blood
.
2002
;
100
:
1579
-1583.
25
Avet-Loiseau H, Gerson F, Magrangeas F, Minvielle S, Harousseau JL, Bataille R. Rearrangements of the c-myc oncogene are present in 15% of primary human multiple myeloma tumors.
Blood
.
2001
;
98
:
3082
-3086.
26
Shou Y, Martelli ML, Gabrea A, et al. Diverse karyotypic abnormalities of the c-myc locus associated with c-myc dysregulation and tumor progression in multiple myeloma.
Proc Natl Acad Sci U S A
.
2000
;
97
:
228
-233.
27
Bergsagel PL, Kuehl WM. Critical roles for immunoglobulin translocations and cyclin D dysregulation in multiple myeloma.
Immunol Rev
.
2003
;
194
:
96
-104.
28
Tarte K, De Vos J, Thykjaer T, et al. Generation of polyclonal plasmablasts from peripheral blood B cells: a normal counterpart of malignant plasmablasts.
Blood
.
2002
;
100
:
1113
-1122.
29
Zhan F, Hardin J, Kordsmeier B, et al. Global gene expression profiling of multiple myeloma, monoclonal gammopathy of undetermined significance, and normal bone marrow plasma cells.
Blood
.
2002
;
99
:
1745
-1757.
30
Shaughnessy J Jr, Gabrea A, Qi Y, et al. Cyclin D3 at 6p21 is dysregulated by recurrent chromosomal translocations to immunoglobulin loci in multiple myeloma.
Blood
.
2001
;
98
:
217
-223.
31
Smadja NV, Bastard C, Brigaudeau C, Leroux D, Fruchart C. Hypodiploidy is a major prognostic factor in multiple myeloma.
Blood
.
2001
;
98
:
2229
-2238.
32
Smadja NV, Leroux D, Soulier J, et al. Further cytogenetic characterization of multiple myeloma confirms that 14q32 translocations are a very rare event in hyperdiploid cases.
Genes Chromosomes Cancer
.
2003
;
38
:
234
-239.
33
Fonseca R, Debes-Marun CS, Picken EB, et al. The recurrent IgH translocations are highly associated with nonhyperdiploid variant multiple myeloma.
Blood
.
2003
;
102
:
2562
-2567.
34
Urashima M, Teoh G, Ogata A, et al. Characterization of p16INK4A expression in multiple myeloma and plasma cell leukemia.
Clin Cancer Res
.
1997
;
3
:
2173
-2179.
35
Guillerm G, Gyan E, Wolowiec D, et al. p16(INK4a) and p15(INK4b) gene methylations in plasma cells from monoclonal gammopathy of undetermined significance.
Blood
.
2001
;
98
:
244
-246.
36
Bezieau S, Devilder MC, Avet-Loiseau H, et al. High incidence of N and K-Ras activating mutations in multiple myeloma and primary plasma cell leukemia at diagnosis.
Hum Mut
.
2001
;
18
:
212
-224.
37
Liu P, Leong T, Quam L, et al. Activating mutations of N- and K-ras in multiple myeloma show different clinical associations: analysis of the Eastern Cooperative Oncology Group Phase III Trial.
Blood
.
1996
;
88
:
2699
-2706.
38
Fonseaca R, Price-Troska T, Blood E, et al. Implication of N-ras and K-ras mutation in clinical outcome and biology of multiple myeloma [abstract].
Blood
.
2003
;
102
:
113a
.
39
Drach J, Ackermann J, Fritz E, et al. Presence of a p53 gene deletion in patients with multiple myeloma predicts for short survival after conventional-dose chemotherapy.
Blood
.
1998
;
92
:
802
-809.
40
Juge-Morineau N, Harousseau JL, Amiot M, Bataille R. The retinoblastoma susceptibility gene RB-1 in multiple myeloma.
Leuk Lymphoma
.
1997
;
24
:
229
-237.
41
Kulkarni MS, Daggett JL, Bender TP, Kuehl WM, Bergsagel PL, Williams ME. Frequent inactivation of the cyclin-dependent kinase inhibitor p18 by homozygous deletion in multiple myeloma cell lines: ectopic p18 expression inhibits growth and induces apoptosis.
Leukemia
.
2002
;
16
:
127
-134.
42
Hyun T, Yam A, Pece S, et al. Loss of PTEN expression leading to high Akt activation in human multiple myelomas.
Blood
.
2000
;
96
:
3560
-3568.
43
Ge NL, Rudikoff S. Expression of PTEN in PTEN-deficient multiple myeloma cells abolishes tumor growth in vivo.
Oncogene
.
2000
;
19
:
4091
-4095.
44
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.
45
Shaughnessy J, Jacobson J, Sawyer J, et al. Continuous absence of metaphase-defined cytogenetic abnormalities, especially of chromosome 13 and hypodiploidy, ensures long-term survival in multiple myeloma treated with Total Therapy I: interpretation in the context of global gene expression.
Blood
.
2003
;
101
:
3849
-3856.
46
Soverini S, Cavo M, Cellini C, et al. Cyclin D1 overexpression is a favorable prognostic variable for newly diagnosed multiple myeloma patients treated with high-dose chemotherapy and single or double autologous transplantation.
Blood
.
2003
;
102
:
1588
-1594.
47
Garand R, Avet-Loiseau H, Accard F, Moreau P, Harousseau JL, Bataille R. t(11;14) and t(4;14) translocations correlated with mature lymphoplasmacytoid and immature morphology, respectively, in multiple myeloma.
Leukemia
.
2003
;
17
:
2032
-2035.
48
Avet-Loiseau H, Garand R, Lode L, Harousseau JL, Bataille R. Translocation t(11;14)(q13;q32) is the hallmark of IgM, IgE, and nonsecretory multiple myeloma variants.
Blood
.
2003
;
101
:
1570
-1571.
49
Fonseca R, Blood EA, Oken MM, et al. Myeloma and the t(11;14)(q13;q32); evidence for a biologically defined unique subset of patients.
Blood
.
2002
;
99
:
3735
-3741.
50
Malumbres M, Barbacid M. To cycle or not to cycle: a critical decision in cancer.
Nat Rev Cancer
.
2001
;
1
:
222
-231.
51
Zhu WG, Otterson GA. The interaction of histone deacetylase inhibitors and DNA methyltransferase inhibitors in the treatment of human cancer cells.
Curr Med Chem Anti-Canc Agents
.
2003
;
3
:
187
-199.
52
Caraglia M, Tagliaferri P, Budillon A, Abbruzzese A. Post-translational modifications of eukaryotic initiation factor-5A (eIF-5A) as a new target for anti-cancer therapy.
Adv Exp Med Biol
.
1999
;
472
:
187
-198.
53
Palakurthi SS, Fluckiger R, Aktas H, et al. Inhibition of translation initiation mediates the anticancer effect of the n-3 polyunsaturated fatty acid eicosapentaenoic acid.
Cancer Res
.
2000
;
60
:
2919
-2925.
54
Dragnev KH, Freemantle SJ, Spinella MJ, Dmitrovsky E. Cyclin proteolysis as a retinoid cancer prevention mechanism.
Ann N Y Acad Sci
.
2001
;
952
:
13
-22.
55
Tsutsumi S, Yanagawa T, Shimura T, et al. Regulation of cell proliferation by autocrine motility factor/phosphoglucose isomerase signaling.
J Biol Chem
.
2003
;
278
:
32165
-32172.
56
Sherr CJ, McCormick F. The RB and p53 pathways in cancer.
Cancer Cell
.
2002
;
2
:
103
-112.
57
Trudel S, Ely SA, Farooqi Y, et al. Inhibition of fibroblast growth factor 3 induces differentiation and apoptosis in t(4;14) myeloma.
Blood
. Prepublished on January 8,
2004
, as DOI 10.1182/blood-2003-10-3650. (Now available as Blood. 2004; 103:3521-3528.)
58
Tian E, Zhan F, Walker R, et al. The role of the Wnt-signaling antagonist DKK1 in the development of osteolytic lesions in multiple myeloma.
N Engl J Med
.
2003
;
349
:
2483
-2494.
59
Facon T, Avet-Loiseau H, Guillerm G, et al. Chromosome 13 abnormalities identified by FISH analysis and serum beta2-microglobulin produce a powerful myeloma staging system for patients receiving high-dose therapy.
Blood
.
2001
;
97
:
1566
-1571.
60
Hideshima T, Nakamura N, Chauhan D, Anderson KC. Biologic sequelae of interleukin-6 induced PI3-K/Akt signaling in multiple myeloma.
Oncogene
.
2001
;
20
:
5991
-6000.
61
Diehl JA, Cheng M, Roussel MF, Sherr CJ. Glycogen synthase kinase-3beta regulates cyclin D1 proteolysis and subcellular localization.
Genes Dev
.
1998
;
12
:
3499
-3511.
62
Hinz M, Krappmann D, Eichten A, Heder A, Scheidereit C, Strauss M. NF-kappaB function in growth control: regulation of cyclin D1 expression and G0/G1-to-S-phase transition.
Mol Cell Biol
.
1999
;
19
:
2690
-2698.
63
Guttridge DC, Albanese C, Reuther JY, Pestell RG, Baldwin AS Jr. NF-kappaB controls cell growth and differentiation through transcriptional regulation of cyclin D1.
Mol Cell Biol
.
1999
;
19
:
5785
-5799.
64
Teoh G, Anderson KC. Interaction of tumor and host cells with adhesion and extracellular matrix molecules in the development of multiple myeloma.
Hematol Oncol Clin North Am
.
1997
;
11
:
27
-42.
65
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.
66
Hazlehurst LA, Damiano JS, Buyuksal I, Pledger WJ, Dalton WS. Adhesion to fibronectin via beta1 integrins regulates p27kip1 levels and contributes to cell adhesion mediated drug resistance (CAM-DR).
Oncogene
.
2000
;
19
:
4319
-4327.
67
Hazlehurst LA, Enkemann SA, Beam CA, et al. Genotypic and phenotypic comparisons of de novo and acquired melphalan resistance in an isogenic multiple myeloma cell line model.
Cancer Res
.
2003
;
63
:
7900
-7906.
68
Lichtenstein A, Tu Y, Fady C, Vescio R, Berenson J. Interleukin-6 inhibits apoptosis of malignant plasma cells.
Cell Immunol
.
1995
;
162
:
248
-255.
69
Chauhan D, Pandey P, Ogata A, et al. Dexamethasone induces apoptosis of multiple myeloma cells in a JNK/SAP kinase independent mechanism.
Oncogene
.
1997
;
15
:
837
-843.
70
Chauhan D, Kharbanda S, Ogata A, et al. Interleukin-6 inhibits Fas-induced apoptosis and stress-activated protein kinase activation in multiple myeloma cells.
Blood
.
1997
;
89
:
227
-234.
71
Tu Y, Gardner A, Lichtenstein A. The phosphatidylinositol 3-kinase/AKT kinase pathway in multiple myeloma plasma cells: roles in cytokine-dependent survival and proliferative responses.
Cancer Res
.
2000
;
60
:
6763
-6770.
72
Mitsiades CS, Mitsiades N, Kung AL, et al. The IGF/IGF-1R system is a major therapeutic target for multiple myeloma, other hematologic malignancies and solid tumors [abstract].
Blood
.
2002
;
100
:
170a
.
73
Hideshima T, Anderson KC. Molecular mechanisms of novel therapeutic approaches for multiple myeloma.
Nat Rev Cancer
.
2002
;
2
:
927
-937.
74
Dhodapkar MV, Abe E, Theus A, et al. Syndecan-1 is a multifunctional regulator of myeloma pathobiology: control of tumor cell survival, growth, and bone cell differentiation.
Blood
.
1998
;
91
:
2679
-2688.
75
Kaushal GP, Xiong X, Athota AB, Rozypal TL, Sanderson RD, Kelly T. Syndecan-1 expression suppresses the level of myeloma matrix metalloproteinase-9.
Br J Haematol
.
1999
;
104
:
365
-373.
76
Chauhan D, Uchiyama H, Akbarali Y, et al. Multiple myeloma cell adhesion-induced interleukin-6 expression in bone marrow stromal cells involves activation of NF-kB.
Blood
.
1996
;
87
:
1104
-1112.
77
Hideshima T, Richardson P, Chauhan D, et al. The proteasome inhibitor PS-341inhibits growth, induces apoptosis, and overcomes drug resistance in human multiple myeloma cells.
Cancer Res
.
2001
;
61
:
3071
-3076.
78
Hideshima T, Chauhan D, Richardson P, et al. NF-kB as a therapeutic target in multiple myeloma.
J Biol Chem
.
2002
;
277
:
16639
-16647.
79
Hideshima T, Chauhan D, Schlossman RL, Richardson PR, Anderson KC. Role of TNF-a in the pathophysiology of human multiple myeloma: therapeutic applications.
Oncogene
.
2001
;
20
:
4519
-4527.
80
Urashima M, Ogata A, Chauhan D, et al. Transforming growth factor b1: Differential effects on multiple myeloma versus normal B cells.
Blood
.
1996
;
87
:
1928
-1938.
81
Dankar 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.
82
Urashima M, Chen BP, Chen S, et al. The development of a model for the homing of multiple myeloma cells to human bone marrow.
Blood
.
1997
;
90
:
754
-765.
83
Yaccoby S, Barlogie B, Epstein J. Primary myeloma cells growting in SCID-hu mice: a model for studying the biology and treatment of myeloma and its manifestations.
Blood
.
1998
;
92
:
2908
-2913.
84
Yaccoby S, Johnson CL, Mahaffey SC, Wezeman MJ, Barlogie B, Epstein J. Antimyeloma efficacy of thalidomide in the SCID-hu model.
Blood
.
2002
;
100
:
4162
-4168.
85
Mitsiades CS, Mitsiades N, McMullan CJ, et al. In vitro and in vivo molecular profiling of multiple myeloma (MM) cell interaction with bone marrow (BM) microenvironment: insight into the role of novel anti-MM agents in counteracting BM-mediated drug-resistance in MM [abstract].
Blood
.
2003
;
102
:
441a
.
86
Mitsiades CS, Mitsiades NS, Bronson RT, et al. Fluorescence imaging of multiple myeloma cells in a clinically relevant SCID/NOD in vivo model: biologic and clinical implications.
Cancer Res
.
2003
;
63
:
6689
-6696.
87
Mitsiades CS, Mitsiades N, Poulaki V, Akiyama M, Treon SP, Anderson KC. The HSP90 molecular chaperone as a novel therapeutic target in hematologic malignancies [abstract].
Blood
.
2001
;
98
:
377a
.
88
Villunger A, Egle A, Kos M, Hittmair A, Maly K, Greil R. Constituents of autocrine IL-6 loops in myeloma cell lines and their targeting for suppression of neoplastic growth by antibody strategies.
Int J Cancer
.
1996
;
65
:
498
-505.
89
Klein B, Zhang XG, Jourdan M, et al. Paracrine rather than autocrine regulation of myeloma-cell growth and differentiation by interleukin-6.
Blood
.
1989
;
73
:
517
-526.
90
Ballester OF, Moscinski LC, Lyman GH, et al. High levels of interleukin-6 are associated with low tumor burden and low growth fraction in multiple myeloma.
Blood
.
1994
;
83
:
1903
-1908.
91
Urashima M, Chauhan D, Uchiyama H, Freeman GJ, Anderson KC. CD40 ligand triggered interleukin-6 secretion in multiple myeloma.
Blood
.
1995
;
85
:
1903
-1912.
92
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.
93
Ishikawa H, Tsuyama N, Abroun S, et al. Requirements of src family kinase activity associated with CD45 for myeloma cell proliferation by interleukin-6.
Blood
.
2002
;
15
:
2172
-2178.
94
Bataille R, Robillard N, Pellat-Deceunynck C, Amiot M. A cellular model for myeloma cell growth and maturation based on an intraclonal CD45 hierarchy.
Immunol Rev
.
2003
;
194
:
105
-111.
95
Taga T, Hibi M, Hirata Y, et al. Interleukin-6 triggers the association of its receptor with a possible signal transducer, gp130.
Cell
.
1989
;
58
:
573
-581.
96
Nishimoto N, Ogata A, Shima Y, et al. Oncostatin M, leukemia inhibitory factor, and interleukin 6 induce the proliferation of human plasmacytoma cells via the common signal transducer, gp130.
J Exp Med
.
1994
;
179
:
1343
-1347.
97
Matsuda T, Fukada T, Takahashi-Tezuka M, et al. Activation of Fes tyrosine kinase by gp130, an interleukin-6 family cytokine signal transducer, and their association.
J Biol Chem
.
1995
;
270
:
11037
-11039.
98
Kurth I, Horsten U, Pflanz S, et al. Activation of the signal transducer glycoprotein 130 by both IL-6 and IL-11 requires two distinct binding epitopes.
J Immunol
.
1999
;
162
:
1480
-1487.
99
Neumann C, Zehentmaier G, Danhauser-Riedl S, Emmerich B, Hallek M. Interleukin-6 induces tyrosine phosphorylation of the Ras activating protein Shc, and its complex formation with Grb2 in the human multiple myeloma cell line LP-1.
Eur J Immunol
.
1996
;
26
:
379
-384.
100
Ogata A, Chauhan D, Teoh G, et al. Interleukin-6 triggers cell growth via the ras-dependent mitogen-activated protein kinase cascade.
J Immunol
.
1997
;
159
:
2212
-2221.
101
Catlett-Falcone R, Landowski TH, Oshiro MM, et al. Constitutive activation of STAT-3 signaling confers resistance to apoptosis in human U266 myeloma cells.
Immunity
.
1999
;
10
:
105
-115.
102
Ochiai N, Uchida R, Fuchida S, et al. Effect of farnesyl transferase inhibitor R115777 on the growth of fresh and cloned myeloma cells in vitro.
Blood
.
2003
;
102
:
3349
-3353.
103
Cortes J, Albitar M, Thomas D, et al. Efficacy of the farnesyl transferase inhibitor R115777 in chronic myeloid leukemia and other hematologic malignancies.
Blood
.
2003
;
101
:
1692
-1697.
104
Hu L, Shi Y, Hsu JH, Gera J, Van Ness B, Lichtenstein A. Downstream effectors of oncogenic ras in multiple myeloma cells.
Blood
.
2003
;
101
:
3126
-3135.
105
Puthier D, Bataille R, Amiot M. IL-6 up-regulates mcl-1 in human myeloma cells through JAK/STAT rather than ras/MAP kinase pathway.
Eur J Immunol
.
1999
;
29
:
3945
-3950.
106
Zhang B, Gojo I, Fenton RG. Myeloid cell factor-1 is a critical survival factor for multiple myeloma.
Blood
.
2002
;
99
:
1885
-1893.
107
Jourdan M, Veyrune JL, Vos JD, Redal N, Couderc G, Klein B. A major role for Mcl-1 antiapoptotic protein in the IL-6-induced survival of human myeloma cells.
Oncogene
.
2003
;
22
:
2950
-2959.
108
Oshiro MM, Landowski TH, Catlett-Falcone R, et al. Inhibition of JAK kinase activity enhances Fas-mediated apoptosis but reduces cytotoxic activity of topoisomerase II inhibitors in U266 myeloma cells.
Clin Cancer Res
.
2001
;
7
:
4262
-4271.
109
Zhang B, Potyagaylo V, Fenton RG. IL-6-independent expression of Mcl-1 in human multiple myeloma.
Oncogene
.
2003
;
22
:
1848
-1859.
110
Derenne S, Monia B, Dean NM, et al. Antisense strategy shows that Mcl-1 rather than Bcl-2 or Bcl-x(L) is an essential survival protein of human myeloma cells.
Blood
.
2002
;
100
:
194
-199.
111
Gojo I, Zhang B, Fenton RG. The cyclin-dependent kinase inhibitor flavopiridol induces apoptosis in multiple myeloma cells through transcriptional repression and down-regulation of Mcl-1.
Clin Cancer Res
.
2002
;
8
:
3527
-3538.
112
Hardin J, Macleod S, Grigorieva I, et al. Interleukin-6 prevents dexamethasone-induced myeloma cell death.
Blood
.
1994
;
84
:
3063
-3070.
113
Chauhan D, Pandey P, Ogata A, et al. Cytochrome-c dependent and independent induction of apoptosis in multiple myeloma cells.
J Biol Chem
.
1997
;
272
:
29995
-29997.
114
Chauhan D, Hideshima T, Rosen S, Reed JC, Kharbanda S, Anderson KC. Apaf-1/cytochrome c independent and Smac dependent induction of apoptosis in multiple myeloma cells.
J Biol Chem
.
2001
;
276
:
24453
-24456.
115
Cardone MH, Roy N, Stennicke HR, et al. Regulation of cell death protease caspase-9 by phosphorylation.
Science
.
1998
;
282
:
1318
-1321.
116
Brunet A, Bonni A, Zigmond MJ, et al. Akt promotes cell survival by phosphorylating and inhibiting a Forkhead transcription factor.
Cell
.
1999
;
96
:
857
-868.
117
Wen XY, Stewart AK, Sooknanan RR, et al. Identification of c-myc promoter-binding protein and X-box binding protein 1 as interleukin-6 target genes in human multiple myeloma cells.
Int J Oncol
.
1999
;
15
:
173
-178.
118
Chauhan D, Li G, Auclair D, et al. Identification of genes regulated by 2-methoxyestradiol (2ME2) in multiple myeloma cells using oligonucleotide arrays.
Blood
.
2003
;
101
:
3606
-3614.
119
Reimold AM, Iwakoshi NN, Manis J, et al. Plasma cell differentiation requires the transcription factor XBP-1.
Nature
.
2001
;
412
:
300
-307.
120
Lee AH, Iwakoshi NN, Anderson KC, Glimcher LH. Proteasome inhibitors disrupt the unfolded protein response in myeloma cells.
Proc Natl Acad Sci U S A
.
2003
;
100
:
9946
-9951.
121
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.
122
Pulkki K, Pelliniemi TT, Rajamaki A, Tienhaara A, Laakso M, Lahtinen R. Soluble interleukin-6 receptor as a prognostic factor in multiple myeloma.
Br J Haematol
.
1996
;
92
:
370
-374.
123
Kyrtsonis MC, Dedoussis G, Zervas C, et al. Soluble interleukin-6 receptor (sIL-6R), a new prognostic factor in multiple myeloma.
Br J Haematol
.
1996
;
93
:
398
-400.
124
Stasi R, Brunetti M, Parma A, Di Giulio C, Terzoli E, Pagano A. The prognostic value of soluble interleukin-6 receptor in patients with multiple myeloma.
Cancer
.
1998
;
82
:
1860
-1866.
125
Huang YW, Vitetta ES. A monoclonal anti-human IL-6 receptor antibody inhibits the proliferation of human myeloma cells.
Hybridoma
.
1993
;
12
:
621
-630.
126
Savino R, Ciapponi L, Lahm A, et al. Rational design of a receptor super-antagonist of human interleukin-6.
Embo J
.
1994
;
13
:
5863
-5870.
127
Montero-Julian FA, Klein B, Gautherot E, Brailly H. Pharmacokinetic study of anti-interleukin-6 (IL-6) therapy with monoclonal antibodies: enhancement of IL-6 clearance by cocktails of anti-IL-6 antibodies.
Blood
.
1995
;
85
:
917
-924.
128
Keller ET, Ershler WB. Effect of IL-6 receptor antisense oligodeoxynucleotide on in vitro proliferation of myeloma cells.
J Immunol
.
1995
;
154
:
4091
-4098.
129
Demartis A, Bernassola F, Savino R, Melins G, Ciliberto G. Interleukin-6 receptor superantagonists are potent inducers of human multiple myeloma cell death.
Cancer Res
.
1996
;
56
:
4213
-4218.
130
Ge NL, Rudikoff S. Insulin-like growth factor I is a dual effector of multiple myeloma cell growth.
Blood
.
2000
;
96
:
2856
-2861.
131
Qiang YW, Kopantzev E, Rudikoff S. Insulinlike growth factor-I signaling in multiple myeloma: downstream elements, functional correlates, and pathway cross-talk.
Blood
.
2002
;
99
:
4138
-4146.
132
Mitsiades CS, Mitsiades N, Poulaki V, et al. Activation of NF-kB and upregulation of intracellular anti-apoptotic proteins via the IGF-1/Akt signaling in human multiple myeloma cells: therapeutic implications.
Oncogene
.
2002
;
21
:
5673
-5683.
133
Akiyama M, Hideshima T, Hayashi T, et al. Cytokines modulate telomerase activity in a human multiple myeloma cell line.
Cancer Res
.
2002
;
62
:
3876
-3882.
134
Akiyama M, Hideshima T, Hayashi T, et al. Nuclear factor-kappaB p65 mediates tumor necrosis factor alpha-induced nuclear translocation of telomerase reverse transcriptase protein.
Cancer Res
.
2003
;
63
:
18
-21.
135
Rajkumar SV, Kyle RA. Angiogenesis in multiple myeloma.
Semin Oncol
.
2001
;
28
:
560
-564.
136
Xu JL, Lai R, Kinoshita T, Nakashima N, Nagasaka T. Proliferation, apoptosis, and intratumoral vascularity in multiple myeloma: correlation with the clinical stage and cytological grade.
J Clin Pathol
.
2002
;
55
:
530
-534.
137
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.
138
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.
139
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.
140
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.
141
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
. Prepublished on November 26,
2003
, as DOI 10.1182/blood-2003-10-3527. (Now available as Blood. 2004;103:3474-3479.)
142
Garrett IR, Durie BG, Nedwin GE, et al. Production of lymphotoxin, a bone-resorbing cytokine, by cultured human myeloma cells.
N Engl J Med
.
1987
;
317
:
526
-532.
143
Lichtenstein A, Berenson D, Norman MP, Chang MP, Carlile A. Production of cytokines by bone marrow cells obtained from patients with multiple myeloma.
Blood
.
1989
;
74
:
1266
-1273.
144
Filella X, Blade J, Guillermo AL, Molina R, Rozman C, Ballesta AM. Cytokines (IL-6, TNF-alpha, IL-1alpha) and soluble interleukin-2 receptor as serum tumor markers in multiple myeloma.
Cancer Detect Prev
.
1996
;
20
:
52
-56.
145
Davies FE, Rollinson SJ, Rawstron AC, et al. High-producer haplotypes of tumor necrosis factor alpha and lymphotoxin alpha are associated with an increased risk of myeloma and have an improved progression-free survival after treatment.
J Clin Oncol
.
2000
;
18
:
2843
-2851.
146
Bang S, Jeong EJ, Kim IK, Jung YK, Kim KS. Fas- and tumor necrosis factor-mediated apoptosis uses the same binding surface of FADD to trigger signal transduction. A typical model for convergent signal transduction.
J Biol Chem
.
2000
;
2000
:
36217
-36222.
147
Qin ZH, Wang Y, Kikly KK, et al. Pro-caspase-8 is predominantly localized in mitochondria and released into cytoplasm upon apoptotic stimulation.
J Biol Chem
.
2001
;
276
:
8079
-8086.
148
Badrichani AZ, Stroka DM, Bilbao G, Curiel DT, Bach FH, Ferran C. Bcl-2 and Bcl-XL serve an anti-inflammatory function in endothelial cells through inhibition of NF-kappaB.
J Clin Invest
.
1999
;
103
:
543
-553.
149
Tsukahara T, Kannagi M, Ohashi T, et al. Induction of Bcl-x(L) expression by human T-cell leukemia virus type 1 Tax through NF-kappaB in apoptosis-resistant T-cell transfectants with Tax.
J Virol
.
1999
;
73
:
7981
-7987.
150
Stehlik C, de Martin R, Kumabashiri I, Schmid JA, Binder BR, Lipp J. Nuclear factor (NF)-kappaB-regulated X-chromosome-linked iap gene expression protects endothelial cells from tumor necrosis factor alpha-induced apoptosis.
J Exp Med
.
1998
;
188
:
211
-216.
151
Wang CY, Mayo MW, Korneluk RG, Goeddel DV, Baldwin AS Jr. NF-kappaB antiapoptosis: induction of TRAF1 and TRAF2 and c-IAP1 and c-IAP2 to suppress caspase-8 activation.
Science
.
1998
;
281
:
1680
-1683.
152
Corral LG, Haslett PAJ, Muller GW, et al. Differential cytokine modulation and T cell activation by two distinct classes of thalidomide analogues that are potent inhibitors of TNF-a.
J Immunol
.
1999
;
163
:
380
-386.
153
Westendorf J, Ahmann G, Armitage R, et al. CD40 expression in malignant plasma cells: Role in stimulation of autocrine IL-6 secretion by a human myeloma cell line.
J Immunol
.
1994
;
152
:
117
-128.
154
Teoh G, Tai YT, Urashima M, et al. CD40 activation mediates p53-dependent cell cycle regulation in human multiple myeloma cell lines.
Blood
.
2000
;
95
:
1039
-1046.
155
Tai YT, Podar K, Mitsiades N, et al. CD40 induces human multiple myeloma cell migration via phosphatidylinositol 3-kinase/AKT/NF-kappa B signaling.
Blood
.
2003
;
101
:
2762
-2769.
156
Hideshima T, Chauhan D, Hayashi T, et al. The biological sequelae of stromal cell-derived factor-1alpha in multiple myeloma.
Mol Cancer Ther
.
2002
;
1
:
539
-544.
157
Sanz-Rodriguez F, Hidalgo A, Teixido J. Chemokine stromal cell-derived factor-1alpha modulates VLA-4 integrin-mediated multiple myeloma cell adhesion to CS-1/fibronectin and VCAM-1.
Blood
.
2001
;
97
:
346
-351.
158
Hayashi T, Hideshima T, Podar K, et al. TGF-b receptor I kinase inhibitor downregulates cytokine secretion and multiple myeloma cell proliferation in the bone marrow microenvironment [abstract].
Blood
.
2003
;
102
:
388b
.
159
Brenne AT, Baade Ro T, Waage A, Sundan A, Borset M, Hjorth-Hansen H. Interleukin-21 is a growth and survival factor for human myeloma cells.
Blood
.
2002
;
99
:
3756
-3762.
160
Burger R, Bakker F, Guenther A, et al. Functional significance of novel neurotrophin-1/B cell-stimulating factor-3 (cardiotrophin-like cytokine) for human myeloma cell growth and survival.
Br J Haematol
.
2003
;
123
:
869
-878.
161
Tamura T, Udagawa N, Takahashi N, et al. Soluble interleukin-6 receptor triggers osteoclast formation by interleukin 6.
Proc Natl Acad Sci U S A
.
1993
;
90
:
11924
-11928.
162
Roodman GD. Biology of osteoclast activation in cancer.
J Clin Oncol
.
2001
;
19
:
3562
-3571.
163
Sezer O, Heider U, Zavrski I, Kuhne CA, Hofbauer LC. RANK ligand and osteoprotegerin in myeloma bone disease.
Blood
.
2003
;
101
:
2094
-2099.
164
Boyle WJ, Simonet WS, Lacey DL. Osteoclast differentiation and activation.
Nature
.
2003
;
423
:
337
-342.
165
Jaeschke H, Lemasters JJ. Apoptosis versus oncotic necrosis in hepatic ischemia/reperfusion injury.
Gastroenterology
.
2003
;
125
:
1246
-1257.
166
Thornberry NA, Lazebnik Y. Caspases: enemies within.
Science
.
1998
;
281
:
1312
-1318.
167
Chauhan D, Hideshima T, Anderson KC. Apoptotic signaling in multiple myeloma: therapeutic implications.
Int J Hematol
.
2003
;
78
:
114
-120.
168
Mitsiades N, Mitsiades CS, Poulaki V, et al. Apoptotic signaling induced by immunomodulatory thalidomide analogs in human multiple myeloma cells: therapeutic implications.
Blood
.
2002
;
99
:
4525
-4530.
169
Chen Q, Gong B, Mahmoud-Ahmed AS, et al. Apo2L/TRAIL and Bcl-2-related proteins regulate type I interferon-induced apoptosis in multiple myeloma.
Blood
.
2001
;
98
:
2183
-2192.
170
Dai Y, Dent P, Grant S. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) promotes mitochondrial dysfunction and apoptosis induced by 7-hydroxystaurosporine and mitogen-activated protein kinase kinase inhibitors in human leukemia cells that ectopically express Bcl-2 and Bcl-xL.
Mol Pharmacol
.
2003
;
64
:
1402
-1409.
171
Hideshima T, Mitsiades C, Akiyama M, et al. Molecular mechanisms mediating antimyeloma activity of proteasome inhibitor PS-341.
Blood
.
2003
;
101
:
1530
-1534.
172
Chauhan D, Li G, Hideshima T, et al. JNK-dependent release of mitochondrial protein, Smac, during apoptosis in multiple myeloma (MM) cells.
J Biol Chem
.
2003
;
278
:
17593
-17596.
173
Hideshima T, Chauhan D, Hayashi T, et al. Antitumor activity of lysophosphatidic acid acyltransferase (LPAAT)-b inhibitors, a novel class of agents, in multiple myeloma.
Cancer Res
.
2003
;
63
:
8428
-8436.
174
Jourdan M, De Vos J, Mechti N, Klein B. Regulation of Bcl-2-family proteins in myeloma cells by three myeloma survival factors: interleukin-6, interferon-alpha and insulin-like growth factor 1.
Cell Death Differ
.
2000
;
7
:
1244
-1252.
175
Rajkumar SV, Hayman S, Gertz MA, et al. Combination therapy with thalidomide plus dexamethasone for newly diagnosed myeloma.
J Clin Oncol
.
2002
;
20
:
4319
-4323.
176
Weber D, Rankin K, Gavino M, Delasalle K, Alexanian R. Thalidomide alone or with dexamethasone for previously untreated multiple myeloma.
J Clin Oncol
.
2003
;
21
:
16
-19.
177
Mitsiades N, Mitsiades CS, Richardson PG, et al. The proteasome inhibitor PS-341 potentiates sensitivity of multiple myeloma cells to conventional chemotherapeutic agents: therapeutic applications.
Blood
.
2003
;
101
:
2377
-2380.
178
Orlowski RZ, Hall M, Voorhees P, et al. Phase I study of the proteasome inhibitor bortezomib (PS-341, Velcade) in combination with pegylated liposomal doxorubicin (Doxil) in patients with refractory helatologic malignancies [abstract].
Blood
.
2002
;
100
:
105a
.
179
Yang HH, Swift R, Sadler K, et al. A phase I/II trial of Velcadeā„¢ and melphalan combination therapy (Ve+M) for patients with relapsed or refractory multiple myeloma (MM) [abstract].
Blood
.
2003
;
102
:
235a
.
180
Hideshima T, Chauhan D, Shima Y, et al. Thalidomide and its analogues overcome drug resistance of human multiple myeloma cells to conventional therapy.
Blood
.
2000
;
96
:
2943
-2950.
181
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.
182
Lentzsch S, LeBlanc R, Podar K, et al. Immunodulatory analogs of thalidomide inhibit growth of HS Sultan cells and angiogenesis in vivo.
Leukemia
.
2003
;
17
:
41
-44.
183
Hayashi T, Hideshima T, Akiyama M, et al. Ex vivo induction of multiple myeloma-specific cytotoxic T lymphocytes.
Blood
.
2003
;
102
:
1435
-1442.
184
Mitsiades N, Mitsiades CS, Poulaki V, et al. Molecular sequelae of proteasome inhibition in human multiple myeloma cells.
Proc Natl Acad Sci U S A
.
2002
;
99
:
14374
-14379.
185
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.
186
Hideshima T, Chauhan D, Hayashi T, et al. Proteasome inhibitor PS-341 abrogates IL-6 triggered signaling cascades via caspase-dependent downregulation of gp130 in multiple myeloma.
Oncogene
.
2003
;
22
:
8386
-8393.
187
Mitsiades N, Mitsiades CS, Richardson PG, et al. Molecular sequelae of histone deacetylase inhibition in human malignant B cells.
Blood
.
2003
;
101
:
4055
-4062.
188
Catley L, Weisberg E, Tai YT, et al. NVP-LAQ824 is a potent novel histone deacetylase inhibitor with significant activity against multiple myeloma.
Blood
.
2003
;
102
:
2615
-2622.
189
Chauhan D, Catley L, Hideshima T, et al. 2-Methoxyestradiol overcomes drug resistance in multiple myeloma cells.
Blood
.
2002
;
100
:
2187
-2194.
190
Hayashi T, Hideshima T, Akiyama M, et al. Arsenic trioxide inhibits growth of human multiple myeloma cells in the bone marrow microenvironment.
Mol Cancer Ther
.
2002
;
1
:
851
-860.
191
Shammas MA, Shmookler Reis RJ, Koley H, et al. Telomerase inhibition and apoptotic cell death following Telomestatin treatment of multiple myeloma [abstract].
Blood
.
2002
;
100
:
810a
.
192
Mitsiades CS, Treon SP, Mitsiades N, et al. TRAIL/Apo2L ligand selectively induces apoptosis and overcomes drug resistance in multiple myeloma: therapeutic applications.
Blood
.
2001
;
98
:
795
-804.
193
Mitsiades CS, Mitsiades N, Poulaki V, et al. HMG-CoA inhibitors (statins) induce growth arrest, apoptosis of multiple myeloma (MM) and Waldenstrom's Macroglobulinemia (WM) cells and enhance their sensitivity to conventional or novel therapies. Molecular profiling of HMG-CoA inhibition in MM/WM and framework for translation to therapeutic application [abstract].
Blood
.
2002
;
100
:
597a
.
194
Hideshima T, Akiyama M, Hayashi T, et al. Targeting p38 MAPK inhibits multiple myeloma cell growth in the bone marrow milieu.
Blood
.
2003
;
101
:
703
-705.
195
Richardson PG, Barlogie B, Berenson J, et al. A phase 2 study of bortezomib in relapsed, refractory myeloma.
N Engl J Med
.
2003
;
348
:
2609
-2617.
196
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.
197
Munshi NC, Hideshima T, Carrasco D, et al. Identification of genes modulated in multiple myeloma using genetically identical twin samples.
Blood
.
2004
;
103
:
1799
-1806.
Sign in via your Institution