Effects of Cyclosporin A and α-Difluoromethylornithine on the Growth of Hamster Pancreatic Cancer In Vitro<xref ref-type="fn" rid="FN2">2</xref><xref ref-type="fn" rid="FN3">3</xref>

Abstract

The growth and survival of hamster H2T pancreatic ductal adenocarcinoma in vitro are known to be significantly reduced by inhibitors of polyamine biosynthesis. alpha-Difluoromethylornithine (alpha-DFMO) is a specific and irreversible inhibitor of ornithine decarboxylase, the rate-limiting enzyme in polyamine biosynthesis. alpha-DFMO treatment inhibits the growth of H2T pancreatic cancer cells and decreases H2T cell survival in vitro and in vivo. In the present study, the effects of cyclosporin A (CsA) were examined on growth, survival, and polyamine levels in H2T pancreatic ductal adenocarcinoma in vitro. CsA had inhibitory effects on H2T pancreatic cancer growth similar to those of alpha-DFMO; these effects were blocked by the addition of the polyamine putrescine. Polyamine levels were found to be significantly altered in cells treated with CsA and/or alpha-DFMO. The combination of CsA (8.3 X 10(-4) mM) and alpha-DFMO (0.5 mM or 1.0 mM) inhibited H2T cell survival to a greater extent than either agent alone. These results suggest that CsA in combination with other agents that inhibit polyamine synthesis may be useful for the treatment of pancreatic cancer.