Cisplatin resistance associated with hypersensitivity to CD95-mediated apoptosis in epidermoid carcinoma cell KB/DDP5 subline

The cisplatin resistant epidermoid carcinoma subline, KB/DDP5, was develope d from the parental cell line, KB. We found that the level of CD95/Fas-anti gen expression is higher on cell subline, KB/DDP5, than on the parental cel l line, KB. After the cisplatin treatment, the level of CD95 expression was upregulated only on KB cell line. We also show that drug resistant cell su bline, KB/DDP5, is hypersensitive to CD95-mediated apoptosis induced by ago nistic monoclonal antibodies IPO-4 (IgM). Combined treatment with IPO-4 and cisplatin results in a synergistic cytotoxic effect in cisptatin-resistant KB/DDP5 and especially sensitive KB cell line.