Enhancement of the Sensitivity of Renal Cell Carcinoma Cells to Fas-Mediated Cytotoxicity and Apoptosis by the Selective Cyclooxygenase-2 Inhibitor JTE-522

Abstract

Background: Cyclooxygenase-2 (COX-2) is a key enzyme involved in the production of prostaglandins and its inhibitors have been shown to induce apoptosis in a variety of cancer cells. We reasoned that combination treatment of renal cell carcinoma (RCC) cells with COX-2 inhibitors and anticancer agents may result in synergistic apoptosis. We examined whether the selective COX-2 inhibitor JTE-522 synergizes with anticancer agents in cytotoxicity and apoptosis against RCC cells. Methods: The cytotoxicity of the selective COX-2 inhibitor JTE-522 and other anticancer agents against the RCC cell lines and the normal renal cell line was determined by the microculture tetrazolium dye assay. Results: JTE-522 was cytotoxic against the Caki-1 RCC cell line. JTE-522 and anti-Fas monoclonal antibody (CH-11) exhibited a synergistic cytotoxic effect against Caki-1 cells. In contrast, JTE-522 in combination with 5-fluorouracil, adriamycin, cis-diamminedichloroplatinum, or interferon-α, all commonly used clinically, resulted in an additive cytotoxic effect. Synergy achieved in cytotoxicity with JTE-522 and CH-11 was shown to be due to apoptosis. Conclusions: The present study demonstrated that the selective COX-2 inhibitor JTE-522 had a cytotoxic effect on RCC and that synergistic cytotoxicity against RCC was obtained with JTE-522 in combination with anti-Fas monoclonal antibody. These results suggest that selective COX-2 inhibitors in combination with immunotherapy may be useful in treating patients with RCC.