p53 and transformation by SV40.

The large T antigen of SV40 is able to immortalize and transform primary and established cells in culture, and can, at least in certain cases, confer a tumorigenic phenotype on the infected cell. T antigen has been shown to induce cellular DNA synthesis in the infected cell and this activity is likely to be instrumental in T antigen mediated oncogenesis. A property of T antigen which may be of paramount importance to its oncogenic and mitogenic activities is its ability to specifically bind and stabilize the cellular protein p53. p53 has been implicated in the control of the passage of the cell from G0 arrest to G1 and S phase. Furthermore, altered p53 expression is strongly associated with various phenotypes of the transformed state, and p53 has been identified as an immortalizing oncogene. Thus it is possible that p53-fixation by T antigen is responsible for its transforming potential. In this article, the transforming activities of T antigen and p53 are reviewed, and the possible relevance of p53-binding to T antigen-induced transformation is discussed.