[Establishment and characterization of a cis-diamminedichloro platinum-resistant human bladder cancer cell line]

A cis-diamminedichloroplatinum (CDDP)-resistant cell line, CL-7/CDDP, has been established by chronic exposure of a parent human bladder cancer cell line, T24 (CL-7), to CDDP at progressively increased concentrations for 20 months. CL-7/CDDP was 2.7-fold more resistant to CDDP than CL-7 as determined by colony formation assay. Biological and biochemical characteristics were examined in CL-7/CDDP to compare with CL-7. There were no differences in doubling time and plating efficiency between the two cell lines, but a small one in the mode of chromosome numbers. Intra-cellular CDDP amounts after CDDP exposure showed no difference between the two cell lines, but CL-7/CDDP showed a higher glutathione (GSH) and metallothionein (MT) level. It is suggested that the mechanism of acquired resistance to CDDP is attributed to intra-cellular detoxication, but not to the efflux. CL-7/CDDP may be useful for elucidation of the mechanism of CDDP resistance in human bladder cancer.