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Excess wild-type p53 blocks initiation and maintenance of simian virus 40 transformation
K Fukasawa1, G Sakoulas, R E Pollack
1Department of Biological Sciences, Columbia University, New York, New York 10027.
Abstract:
Wild-type (wt) murine p53 has been tested for its ability to block and reverse the transforming effects of simian virus 40 (SV40) large T antigen. Established and precrisis mouse cells overexpressing exogenously introduced wt p53 became resistant to SV40 transformation. The introduction of excess wt p53 into SV40-transformed precrisis cells reverted their transformed phenotype. However, the phenotype of SV40-transformed established cells was not reverted by excess wt p53. We conclude that an antioncogenic action of wt p53 is exerted during SV40 transformation and that in precrisis cells, the antitransforming action of wt p53 can be exerted both at initiation and during the maintenance of transformation.
Insights
Wild-type p53 (a tumor suppressor) can prevent and reverse simian virus 40 (SV40) transformation in mouse cells. However, this effect is limited in established cells, suggesting p53
Area of Science:
- Oncology
- Molecular Biology
- Virology
Background:
- Wild-type p53 is a crucial tumor suppressor protein.
- Simian virus 40 (SV40) large T antigen is a known oncogenic driver.
- Cellular transformation is a key step in cancer development.
Purpose of the Study:
- To investigate the role of wild-type p53 in blocking and reversing SV40-induced cellular transformation.
- To determine if p53's antioncogenic activity differs between precrisis and established cells.
Main Methods:
- Overexpression of wild-type murine p53 in mouse cell lines.
- Exposure of cells to SV40 large T antigen.
- Assessment of cellular transformation phenotypes (resistance to transformation and reversion of transformed state).
Main Results:
- Overexpression of wild-type p53 conferred resistance to SV40 transformation in both established and precrisis cells.
- Introduction of excess wild-type p53 reverted the transformed phenotype in SV40-transformed precrisis cells.
- Excess wild-type p53 failed to revert the transformed phenotype in SV40-transformed established cells.
Conclusions:
- Wild-type p53 exhibits antioncogenic activity against SV40 transformation.
- p53's antitransforming action is effective during both the initiation and maintenance phases of transformation in precrisis cells.
- The efficacy of p53 in reversing transformation is dependent on the cellular state (precrisis vs. established).