PURPOSE: To confirm that human cancer cells show p53-dependent heat sensitivity through an apoptosis-related mechanism, we examined the heat sensitivity and Bax-mediated apoptosis after heating in a human squamous cell carcinoma cell line, SAS, with identical genetic backgrounds except for the p53 status. MATERIALS AND METHODS: We performed colony formation assay, Western blotting and analyses of apoptosis, using the SAS cells transfected with pC53-248 vector with mutant p53 gene (SAS/Trp248 cells) or the cells transfected with pCMV-Neo-Bam vector (SAS/neo cells) as a control. RESULTS: SAS/Trp248 cells showed heat resistance due to the dominant negative nature of mp53, compared with SAS/neo cells. The incidence of DNA ladders and apoptotic bodies increased markedly after heating in SAS/neo cells, but increased very little in SAS/Trp248 cells. CONCLUSION: These results suggest that heat resistance brought by mp53-transfection is p53-dependent and closely correlates with the induction of apoptosis in human squamous cell carcinomas.
PURPOSE: To confirm that humancancer cells show p53-dependent heat sensitivity through an apoptosis-related mechanism, we examined the heat sensitivity and Bax-mediated apoptosis after heating in a humansquamous cell carcinoma cell line, SAS, with identical genetic backgrounds except for the p53 status. MATERIALS AND METHODS: We performed colony formation assay, Western blotting and analyses of apoptosis, using the SAS cells transfected with pC53-248 vector with mutant p53 gene (SAS/Trp248 cells) or the cells transfected with pCMV-Neo-Bam vector (SAS/neo cells) as a control. RESULTS:SAS/Trp248 cells showed heat resistance due to the dominant negative nature of mp53, compared with SAS/neo cells. The incidence of DNA ladders and apoptotic bodies increased markedly after heating in SAS/neo cells, but increased very little in SAS/Trp248 cells. CONCLUSION: These results suggest that heat resistance brought by mp53-transfection is p53-dependent and closely correlates with the induction of apoptosis in humansquamous cell carcinomas.