Influence of gastrin on human astrocytic tumor cell proliferation

Background: Gastrin and cholecystokinin (CCK) mediate their effects through at least two types of receptors (CCK receptors A and B). While it has been hypothesized that gastrin, a stimulator of gastric acid secretion, is also a neurotransmitter and a stimulator of cell proliferation in various normal and neoplastic tissues, its effect on astrocytic brain tumors has not been actively investigated. Purpose: Our goal was to determine the effects of gastrin and gastrin and/or CCK antagonists on the proliferation in vitro of astrocytic tumor cells by use of both established cell lines and primary cell cultures of tumor tissue. Methods: Ten established astrocytic tumor cell limes, SW1088, SW1783, Hs683, H4, U87, U118, U138, U373, T98G, and A172, were studied. The effects of added gastrin (at 0.01, 0.1, and 1 mu M) and the gastrin/CCK antagonists L-365,260, CI-988, L-364,718, and JMV 234 (each at 0.01, 0.1, and 1 mu M) on the cellular proliferation rates of the 10 cell lines were indirectly measured by use of the colorimetric tetrazolium assay. The influence of gastrin (at 0.01 mu M) on the cellular proliferation of primary cultures from nine freshly explanted astrocytic tumors was assessed by means of tritiated thymidine uptake and autoradiography. Results: At specific concentrations, added gastrin increased the cellular proliferation of three established astrocytic cell lines (A172, Hs683, and SW1088), decreased it in two (U373 and T98G), and was without effect on the remaining five. Gastrin decreased cellular proliferation in one primary astrocytic tumor cell culture, stimulated it in five, and had no apparent effect in the remaining three. L-365,260, a CCK receptor B antagonist used at 0.01 mu M, increased cellular proliferation in seven cell lines (A172, H4, Hs683, SW1783, T98G, U118, and U138), decreased it in one (U87), and had no effect in the remaining two. CI-988, another CCK receptor B antagonist used at 0.01 mu M, inhibited cellular proliferation in five cell lines (A172, H4, SW1783, U373, and U87), stimulated it in two (T98G and U138), and had no effect in three. The CCK receptor A antagonists L-364,718 and JMV 234, both used at 0.01 mu M, affected the cellular proliferation of only three of the 10 cell lines. Conclusions: These results suggest that gastrin (and perhaps CCK that belongs to the same peptide family) may play a role in the growth of a substantial proportion of human astrocytic tumors.