Interleukin-6 (IL-6) and basic fibroblast growth factor (bFGF) in noncontact cocultures of U-266 myeloma cells and bone marrow stromal cells (BMSCs).
(A) Enhanced IL-6 secretion of BMSCs derived from myeloma patients in transwell cocultures with U-266 cells (P < .01 vs BMSC monocultures). The addition of anti-bFGF or anti-bFGF plus anti-VEGF antibodies resulted in a significant reduction of IL-6 secretion (P = .01 and P = .02, respectively, versus native cocultures containing no antibody). IL-6 secretion by BMSCs and U-266 monocultures served as baseline controls. IL-6 concentrations were determined in serum-free supernatants of 72-hour cultures. Results were corrected for 105 cells and are presented as medians and interquartile ranges of 9 independent coculture experiments with BMSCs from different patients. Analysis of significance for group differences was performed by the Mann-Whitney rank sum test. The insert shows the induction of IL-6 transcripts in BMSCs by noncontact cocultivation with U-266 cells and its reversal by the addition of anti-bFGF antibody (quantitative IL-6 RT-PCR in a representative coculture). Ratios of IL-6 over glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression are depicted as fold increase over the unstimulated control. (B) Increased bFGF secretion into supernatants of transwell cocultures of U-266 cells with BMSCs for 72 hours (P = .03 vs U-266 monocultures). The addition of polyclonal antihuman IL-6 antibody (5 μg/mL) slightly, but not significantly, decreased bFGF secretion. U-266 and BMSC monocultures served as baseline controls. BFGF concentrations were determined in supernatants of serum-free 72-hour cultures. Results were corrected for 106 cells and are presented as medians and interquartile ranges of 3 independent experiments. The insert shows the induction of bFGF transcripts in U-266 myeloma cells by noncontact coincubation with BMSCs and the effect of anti–IL-6 antibody (quantitative bFGF RT-PCR, representative experiment). Ratios of bFGF over glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression are shown as fold increase over the unstimulated control.
