Exogenous Mutant P53 DNA Enhanced Cisplatin-induced Apoptosis in TSGH-8301 Human Bladder Cancer Cells

Background: The influence of tumor suppressor gene p53 on the apoptosis of bladder cancer cells is not completely understood. In this study, the requirement for p53 in the cisplatin-induced apoptosis of human bladder cancer cells TSGH-8301 was investigated.

Materials And Methods: TSGH-8301 cells, which contain endogenous wild type p53 genes, were transfected with expression vectors containing p53 cDNA mutated at codon 173. Stable mutant p53 transfectant clones were confirmed by Southern blotting and Western blotting. The cellular response to cisplatin was determined on the basis of (a) cells viability, (b) apoptotic DNA fragmentation, and (c) nuclear condensation.

Results: Cells containing an exogenous mutant p53 sequence had increased sensitivity to cisplatin by undergoing apoptosis compared with parental TSGH8301 cells. In contrast, no difference was observed in those clones with rearranged or undetectable exogenous mutant p53 cDNA. However, analysis of p53 mRNA with RT-PCR sequencing indicated that none of the transfectant clones expressed exogenous mutant p53 mRNA.

Conclusion: The transfectants had lost the expression of mutant p53 during selection; however, they could still enhance the expression of wild-type p53, which conferred sensitivity to cisplatin.

Implication: Transient expression of mutant p53 protein in TSGH8301 cells may induce an irreversibly stabilization of p53 and increase the steady state of p53 expression.