Effects of octreotide, galanin and serotonin on a human gastric cancer cell line.

Human gastric cancer cell line was exposed in vitro to octreotide, galanin and serotonin alone, or in double or triple combination, and the number of viable cells and proliferation index were measured after 3, 6 and 12 h. The tumour cells were also implanted subcutaneously in nude mice. After 8 days, the animals were randomly allocated to either of two groups, with 8 in each. The first group received a bolus intraperitoneal injection, twice daily with 100 microl sterile saline solution for 10 days, while the second group was given sterile saline solution containing 100 microg/kg body weight of octreotide, galanin and serotonin. In vitro exposure to octreotide, galanin and serotonin alone or in double or triple combination reduced the number of viable cells and proliferation index. Both the volume and weight of tumours in mice given triple therapy were less than in controls. There was no statistical difference between treated and control tumours regarding proliferation and apoptotic indices or the labelling index of epidermal growth factor (EGF). It was concluded that the reduction in tumour volume and weight following triple treatment in vivo experiments could be not explained by inhibition of proliferation, induction of apoptosis or decreased expression of EGF of the tumour cells, and that other mechanisms must be involved. The reduction of proliferation in vitro but not in vivo could not be explained by the difference in concentrations of octreotide, galanin and serotonin used in vitro and in vivo.