PO-284 Involvement of versican, a chondroitin sulfate proteolgycan in the pathogenesis of multiple myeloma

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IntroductionMultiple Myeloma (MM) is second most common haematological malignancy characterised by uncontrolled proliferation of abnormal plasma cells in bone marrow (BM). The growth of these myeloma cells is facilitated by BM niche consisting of numerous proteins, proteoglycans, cytokines and growth factors. One of the chondroitin sulfate proteoglycan, Versican (VCAN) has gained consideration in context of solid tumours where in it has been shown to promote tumour progression but there is dearth of literature in haematological malignancies including MM. Therefore, the involvement of VCAN in association with MM has been studied.Material and methods30 newly diagnosed MM patients and 20 controls were recruited. BM Mononuclear Cells (BMMNCs) were isolated from their BM aspirate. In representative samples (n=15), BM Stromal Cells (BMSCs) were harvested from BMMNCs by primary culture. The relative mRNA expression of VCAN and its four isoforms (V0, V1, V2 and V3) were investigated in BMMNCs, BMSCs and MM cell lines (RPMI8226 and U266). Conditioned medium (CM) of primary cultured BMSCs was collected and examined for presence of VCAN by ELISA. Thereafter, the effect of BMSCs CM was studied on MM cells in presence or absence of VCAN antibody. To accomplish this, PCNA along with MTT assay for proliferation, VEGF for angiogenesis and Bcl-2, PUMA for apoptosis were investigated. Further, the signalling pathways involved in the action of VCAN were also identified.Results and discussionsThe relative mRNA expression of VCAN and its isoforms were found significantly higher in MM patients in both BMMNCs and BMSCs with higher expression in BMSCs than in BMMNCs. VCAN being produced in stroma found at lower levels in MM cell lines. Furthermore, BMSCs CM showed the presence of VCAN whose effect was evaluated in MM cell lines in vitro. Upon treatment with BMSCs CM, proliferation and angiogenesis increase while apoptosis decrease in cell lines, however, effect of CM neutralised in presence of VCAN antibody. The downstream signalling of VCAN was observed to entail phosphorylation of FAK and STAT3 which subsides by treatment with VCAN antibody.ConclusionAugmented levels of VCAN and its isoforms in BM of patients especially in BMSCs imply their involvement in BM microenvironment of MM. The neutralisation of the oncogenic effect of BMSCs CM upon treatment with VCAN antibody affirms the plausible role of VCAN in pathogenesis of MM. These findings open up new avenues for exploration of VCAN as a therapeutic target for treatment of MM in future.