Identification of Novel Angiogenic Proteins in Multiple Myeloma Patient-Derived Endothelial Cells Using Proteome-Wide Analysis.

Abstract 2825

Poster Board II-801

Novel technologies are needed to identify new and more efficient biomarkers and improved molecular targets for accurate diagnosis and treatment of multiple myeloma (MM). Proteomics, i.e., the study of proteins and protein pathways involved in disease, is a new dimension in preclinical and clinical development. Preliminary studies in global protein expression of bone marrow endothelial cells (ECs) of patients with MM (MMECs) and ECs from monoclonal gammopathy of undetermined significance (MGUS-MGECs) vs. human umbilical vein endothelial cells (HUVECs), has shown at least 20 proteins differentially expressed in MMECs. The association of monodimensional electrophoresis with MALDI-MS analysis allowed us to identify a series of proteins that are shown to be important biomarkers to differentiate MMECs vs. MGECs and HUVECs, and distinguish different stages in MM progression, i.e., diagnosis, relapse, and refractory disease. These proteins are known to play important roles in cellular functions such as glycolysis (α-enolase and glyceraldehyde-3-phosphate dehydrogenase), cell-cycle regulation (14-3-3 zeta/delta protein, mitotic checkpoint serine/threonine-protein kinase BUB1), apoptosis (annexin V), angiogenesis and metastasis (vimentin, α-filamin) and they might contribute to the adverse evolution of the disease. Preliminary results suggest that the increased expression of α-filamin in ECs from an active desease, refractory desease and stable desease, the upregulation of vimentin in ECs from an active desease and down regulation of annexin VI in ECs from a refractory desease is related to the cell overangiogenic potential, indicate a common machinery involved with the structural organization of the cytoskeleton and with the connection of matrix and cell–cell external signals with the intracellular signaling pathways. On the other hand, changes in the expression of structural proteins (Filamin, vimentin, alpha-actinin), could account, at least in part, for the different morphologies displayed by migrating endothelial cells. In order to understand the role of these proteins in the angiogenic switch, the molecular targets potentially useful in the antiangiogenic treatment of MM were silenced by siRNA experiments and their potential involvement in migration and proliferation was investigated by proliferation, cell adhesion and invasion essays. This study has delineated the functional profile of the proteome of ECs in patients with MM in order to understand some of the mechanisms involved in neovascularisation and progression of MM and to identify new targets useful in the treatment of these patients. Because angiogenesis and lymphangiogenesis actively contribute to cancer progression, future studies to establish the role of these angiogenic proteins in disease may suggest potential new targets for tissue-specific therapies.