Cisplatin caused highly delayed cytotoxicity in the immortalized cells derived from S3 segment of mouse kidney proximal tubules

Anti-cancer drug cisplatin (CDDP) causes severe acute kidney injury (AKI). CDDP-induced AKI does not occur immediately after administration, but rather 6 to 10 days after administration. However, the mechanism underling the delayed renal injury by CDDP is not well understood. In a previous investigation using immortalized cells derived from the S1, S2, and S3 segments of the proximal tubules, we found that S3 cells were more sensitive to CDDP than S1 and S2 cells. In this study, we examined whether S1, S2, and S3 cells would be useful in elucidating the mechanism of CDDP-induced delayed renal injury and whether the high sensitivity of S3 cells contributes to CDDP-induced delayed renal injury. Measurement of platinum (Pt) content by ICP-MS showed that Pt accumulation peaked at 15 min after CDDP exposure in each cell type. Even when the medium was replaced with CDDP-free medium after the 15-min CDDP exposure and the cells were further incubated, delayed cytotoxicity was still observed. The S3 cells exhibited greater sensitivity to CCDP than the S1 and S2 cells at all time points after the medium change. To investigate the mechanism of the CDDP-induced delayed cytotoxicity, we examined the cell cycle distribution of cells after CDDP exposure. The results showed that CDDP-induced perturbation of cell cycle was greater in S3 than in S1 and S2 cells. These results suggest that perturbation of the cell cycle in S3 cells due to enhanced CDDP–DNA adduct formation contributes to the high susceptibility of S3 cells to CDDP-induced delayed cytotoxicity.