Upregulation of Syndecan-1 in the bone marrow microenvironment in multiple myeloma is associated with angiogenesis

OBJECTIVES: Syndecan-1 (SDC1), hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF) and interleukin-6 (IL6) are expressed by malignant plasma cells and cells in the bone marrow microenvironment and may be involved in the angiogenic process in multiple myeloma (MM).METHODS: In this study, we examined the association between bone marrow angiogenesis estimated as micro-vessel density (MVD) and gene expression of SDC1, HGF, VEGF and IL6 in whole bone marrow biopsies from healthy volunteers (n = 10), patients with monoclonal gammopathy of undetermined significance (MGUS) (n = 35) and MM (n = 65).RESULTS: MVD was significantly higher in patients with MM than MGUS (P = 0.03) and was positively correlated with plasma cell percentage (P = 0.002). SDC1 gene expression increased with increasing MVD in patients with MGUS and MM (P < 0.001). A positive correlation between bone marrow plasma cell percentage and SDC1 gene expression was detected in patients with MM (P < 0.001). Importantly, after adjustment for plasma cell percentage, the association between MVD and SDC1 gene expression remained significant (P = 0.026). No association between bone marrow angiogenesis and gene expression of HGF, VEGF and IL6 was seen.CONCLUSION: Our study indicates that SDC1 expressed by the bone marrow microenvironment is involved in angiogenesis in MM.