Elucidation of the intracellular mechanisms of cisplatin-induced apoptosis in renal cell line

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We have examined the intracellular mechanisms of cisplatin-induced apoptosis in mouse terminal proximal straight tubule (S_3) cell line derived from transgenic mice harboring temperature-sensitive simian virus 40 antigen gene. (1) The involvement of caspase : Using the peptide caspase inhibitor and the introduction of viral gene encoding caspase inhibitor, it appears that caspase-3 is involved in cisplatin-induced apoptosis, whereas some caspases other than caspase-3 in apoptosis induced by staurosporine , protein kinase C inhibitor. Thus, different caspases may be involved in apoptosis in S_3 cells induced by different stimuli. The intranephron distribution of caspase-3 was examined by RT-PCR analysis from mRNA of mouse individual nephron segments. Caspase-3 mRNA was expressed in all of mouse nephron segments tested, and those for distal tubule and collecting duct were the highest. (2) The association with cell cycleprogression 0 : The inhibition of caspases increased the degree of G2 … More arrest in cisplatin-treated S_3 cells, suggesting that the activation of caspases induces apoptosis by decreasing the number of cells arrested at G2 phase of the cell cycle in cisplatin-treated S_3 cells. (3) The involvement of free radical oxygene species : Using fluorescent probe and cofocal laser scanning microscope, H_2O_2 production was detected in cisplatin-treated S_3 cells. The treatment with catalase inhibited H_2O_2 production and the cytotoxicity in cisplatin-induced S_3 cells. In addition, H_2O_2 was shown to induce apoptosis, necrosis, oncosis and apoptotic oncosis in S_3cells. Since DNA fragmentation was detected in H_2O_2-treated S_3 cells, DNA fragmentation appeared not to be unique to apoptosis. (4) The involvement of oncogene : The increase in c-fos mHNA expression was observed in cisplatin-treated S_3 cells. Overexpression of bcl-2 inhibited the activation of caspase-3 and cell death in cisplatin-treated S_3 cellsThese results suggest that caspase, cell cycle progression, free radical oxygen species and oncogene are involved in cisplatin-induced apoptosis in S_3 cells. Less