Effect of VEGF on MM cell proliferation.

MM.1S (panel A) and MM cells isolated from 5 patients (panel B) (3 × 10⁴ cells per well) were cultured in RPMI 1640 medium with 5% (MM.1S) or 10% (patient MM cells) FBS in 96-well assay plates. The cells were then either left untreated or treated with 1 to 1000 ng/mL of VEGF₁₆₅. Cell growth was assessed by addition of 0.5μCi [³H] thymidine [³H (dT)] per well during the last 9 hours of 72-hour cultures at 37°C. Radioactive labeling was determined by harvesting the cells onto glass-fiber filtermates with an automatic cell harvester (Tomec Harvester 96 Mach III) and counting by means of the Wallac Trilux Betaplate scintillation counter. Data represent means and SDs for triplicate samples. Statistical significance for the proliferation of MM.1S cells was determined by analysis of variance followed by an unpaired Student t test: *P < .005; **P < .001, as compared with control (without VEGF).