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.