Effects of gastrin and difluoromethylornithine on growth of human colon cancer

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Abstract
The effect of difluoromethylornithine (DFMO), a specific inhibitor of ornithine decarboxylase activity, was evaluatedin vivo andin vitro on the growth of a gastrin-sensitive human colon carcinoma (WiDr).In vivo, mice bearing the tumor treated with pentagastrin had larger tumors with higher ornithine decarboxylase activity and polyamine content (P3H]thymidine incorporation in the presence or absence of serum. In serum-free conditions, however, gastrin stimulated cell growth without concomitantly increasing ODC activity. DFMO, on the other hand, decreased both ODC activity and growth. These studies suggest that the trophic effect of gastrin on WiDr human colon cancer is independent of ODC activity. Since gastrin treatment increased ODC activityin vivo, gastrin may interactin vitro with other factors present in serum that can alter ODC activity.