[The interaction of vascular endothelial growth factor and interleukin-6 in multiple myeloma].

OBJECTIVE: To study the interaction between human multiple myeloma (MM) cell line and MM-bone marrow stromal cells (BMSCs) modulated by mutual stimulation of vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6), and to analyze the role of VEGF and IL-6 in the pathogenesis of MM. METHODS: MM patient (MM-BMSCs) and normal donor-BMSCs (N-BMSCs) were established from the MNCs of MM and normal bone marrow. ELISA was performed to detect the expression of VEGF and IL-6 in culture supernatants of human MM cell lines U266, MM-BMSCs, N-BMSCs, and co-cultures of U266 and BMSCs in vitro. VEGF and IL-6 were detected in culture supernatants with or without IL-6, anti-IL-6, VEGF, anti-VEGF antibody. RESULTS: Human MM cell line U266 secreted VEGF, but did not secrete IL-6. BMSCs from MM patients and normal donors secreted both VEGF and IL-6. BMSCs stimulated with recombinant human VEGF induced a time and dose-dependent increase in IL-6 secretion. The effects of VEGF were canceled by monoclonal anti-VEGF antibody. Exogenous IL-6 stimulated VEGF secretion of BMSCs. Importantly, when U266 cell were adhered to BMSCs, there was significant increase of VEGF (2.5 - 5.0 fold, P < 0.05) and IL-6 (5.5 - 9.0 fold, P < 0.05) secretion. The secretion of VEGF or IL-6 in BMSCs alone or co-cultures of BMSCs with U266 were inhibited by anti-human IL-6 or anti-human VEGF antibody. U266 cell stimulated with recombinant human IL-6 induced a dose-dependent increase in VEGF secretion, which was inhibited in the presence of a monoclonal antihuman IL-6 antibody. CONCLUSIONS: The interaction between myeloma cells and marrow stromal cells modulates the secretion of VEGF and IL-6, facilitates myeloma cells growth and angiogenesis in MM. It plays an important role in the pathogenesis of MM. This study provides a theoretic basis for target therapy in the treatment of bone marrow microenvironment.