BOMBESIN STIMULATES INTRACELLULAR CA2-CANCER CELLS( MOBILIZATION BUT NOT PROLIFERATION ON HUMAN COLON)

Increases in intracellular Ca2+ ([Ca2+]i) levels mediated by bombesin (BBS) are believed to be important signals leading to stimulation of D NA synthesis and an increase in cellular proliferative rate. Since the role of BBS on growth of normal or malignant cells in the GI tract is still unclear, we examined whether BBS affects in vitro growth of hum an colon cancer cells (COLO 320, HCT116 and LoVo). We also examined th e effect of BBS on intracellular Ca2+ levels to determine if the growt h-regulatory effect of BBS is mediated through increases in [Ca2+]i. L evels of [Ca2+]i in response to BBS were measured by single cell fluor escence after loading with fura-2. BBS stimulated the mobilization of [Ca2+]i in COLO 320, LoVo, and HCT116 cells in a dose-dependent fashio n, but did not affect in vitro growth. These findings suggest that the BBS-mediated increase in [Ca2+]i does not always correlate with the g rowth-regulatory effect of BBS.