Stimulation of growth of a colon cancer cell line by gastrin

The trophic effects of the hormone gastrin-17 were examined on a human colon cancer cell line. LoVo cells were obtained from the American Type Culture Collection and grown in minimal essential medium in the presence of 10% bovine fetal serum. To demonstrate the trophic effect of gastrin, synchronization was necessary. The effect of gastrin was optimal after 26-h exposure to 0.6 mM thymidine. In the presence of serum the optimal dose of gastrin for stimulation of DNA synthesis was 7.2 X 10(-10) M. Under these conditions gastrin caused a 220% increase in [3H]thymidine incorporation. In the absence of serum the optimal dose of gastrin (3.6 X 10(-9) M) increased DNA synthesis approximately 200%. Twenty-four hours after gastrin treatment (1.8 X 10(-10) M gastrin 17) cell numbers increased 50.8% compared with control. At 48 h this increase was maintained at 44%. Maximum stimulation by gastrin occurred 7-8 h after release from synchronization and exposure to gastrin. This corresponded to the S phase of the cell cycle. Significant stimulation occurred a second time at 22-24 h, presumably during the second S phase in a still synchronous or partially synchronous cell population. These data demonstrate that physiological concentrations of gastrin-17 can stimulate the growth of a human cancer cell line and that some degree of synchronization may be necessary to demonstrate similar effects in other cell lines. Such cell lines may provide a source of rapidly growing cells in which the mechanisms of the trophic effect of gastrin can be examined.