Purpose: We sought to determine whether cyclosporin-A (CsA) enhances docetaxel [Taxotere (TXT)]- induced apoptosis in human gastric carcinoma cells, and, if so, to determine the relation between this apoptosis and nuclear factor-kappaB (NF-kappaB) activation.
Experimental design: Two human gastric carcinoma cell lines (GCTM-1 and MK-1), a human embryonic pulmonary fibroblast cell line, and human umbilical vein endothelial cells were used as drug targets. Apoptotic cell death was verified morphologically by nuclear fragmentation assay with Hoechst staining. Electrophoretic mobility shift assays were performed to check for nuclear translocation of NF-kappaB. The therapeutic effects of a combination of TXT and CsA were assessed in a mouse peritoneal dissemination model.
Results: A combination of CsA (5 micro M) and TXT (10 nM) significantly enhanced apoptotic cell death in both carcinoma cell lines but not in nonmalignant cell lines in comparison with the single-agent treatment alone. This effect was not related to drug uptake, efflux, or MDR1 expression. These effects were also observed in freshly obtained TXT-resistant gastric carcinoma cells isolated from a patient with malignant ascites. TXT alone induced NF-kappaB activation in both carcinoma cell types, and this activation was suppressed by CsA. A combination of TXT and NF-kappaB decoy, a well-known NF-kappaB inhibitor, also enhanced apoptotic cell death in the carcinoma cells. A combination of CsA and TXT significantly suppressed peritoneal dissemination in vivo relative to the single-agent effect.
Conclusions: Treatment with CsA and TXT in combination may be an effective therapeutic strategy for patients with gastric carcinoma.