Simian virus 40 T antigen induces p53-independent apoptosis but does not suppress erbB2/neu gene expression in immortalized human epithelial cells.
Previously, we have shown that simian virus 40 (SV40) T antigen can directly cause apoptosis in immortalized human epithelial cells under normal growth conditions. In this study, we further characterized the mechanism of T-antigen-mediated apoptosis involving p53 and whether T antigen can suppress erbB2/neu gene expression. Our results show the differential regulation of erbB2/neu gene expression in different cell clones in response to T antigen transgene, indicating that the regression of erbB2/neu gene by SV40 T is cell-type dependent. Our previous study reported T-antigen-induced apoptosis in p53 mutant cells; however, in this study we find increased levels of p53 protein in T-antigen-containing cells. Therefore, we examined the transactivation function of p53 in these cells. Our data show the failure to transactivate p53, suggesting that increased p53 protein in T antigen expressing cells is functionless at least for transcriptional activation.
Wang
C H
CH
Department of Microbiology and Immunology, National Defense Medical Center, Taipei, Taiwan.
Chen
Y L
YL
Tsao
Y P
YP
Chen
S L
SL
D000957:Antigens, Viral, Tumor / Q000235:genetics / Q000502:physiology*; D017209:Apoptosis / Q000235:genetics* / Q000502:physiology; D002461:Cell Line, Transformed; D015870:Gene Expression; D018734:Genes, erbB-2 / Q000235:genetics / Q000502:physiology*; D006801:Humans; D015533:Transcriptional Activation; D019076:Transgenes; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D000957:Antigens, Viral, Tumor; D016159:Tumor Suppressor Protein p53