Simian virus 40 large tumour antigen is produced but not expressed in revertant cell lines RD2005 and RXHO24.
Revertant cell lines RD2005 and RXHO24 obtained from the reversion of the transformed cell lines TD2005 and TXHO24 produced Simian virus 40 large tumour antigen. Transformed cells resulted in the transfection of the FR3T3 cell line with the mutant plasmids of Simian virus (SV40) called D2005 and XHO24. The first plasmid D2005 encoded the large tumour (LT) antigen in its entire size. The second plasmid XHO24 encoded only a small portion: 19% of the LT-antigen. The analysis of the viral protein by immunoprecipitation showed the production of the LT protein in revertant cells. The LT oncogenes produced in revertant cells could not be expressed, because some cellular factors or some epigenetic and genetic events controlled their expression. The modulation of the expression of a viral oncogene could also be associated with alterations in the chromatin structures. This may explain the loss or the reacquisition of its activity, providing a useful dynamic heterogeneity model of tumoral progression in cancer cells.
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Department of Biology, Laurentian University, Sudbury, Ontario, Canada.
D016475:3T3 Cells; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000096:biosynthesis*; D002461:Cell Line, Transformed; D004279:DNA, Viral / Q000235:genetics; D015967:Gene Expression Regulation, Viral; D018014:Gene Transfer Techniques; D051379:Mice; D009154:Mutation; D010957:Plasmids; D018139:Simplexvirus / Q000235:genetics / Q000378:metabolism*
D000952:Antigens, Polyomavirus Transforming; D004279:DNA, Viral