SV40 large T antigen targets multiple cellular pathways to elicit cellular transformation

• Published in: Oncogene Vol. 24; no. 52; pp. 7729 - 7745
• Main Authors: Ahuja, Deepika, Sáenz-Robles, M Teresa, Pipas, James M
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 21-11-2005
• Subjects: Amino acids; Animals; Antigen T (large); Antigens; Antigens, Polyomavirus Transforming - genetics; Antigens, Polyomavirus Transforming - physiology; Cell Transformation, Neoplastic - genetics; Cell Transformation, Neoplastic - pathology; DNA tumor viruses; DNA viruses; Gene Expression Regulation; Genes, p53; Genes, Retinoblastoma; Genetic transformation; Genomes; Hyperplasia; Infections; Invasiveness; Metastases; Mice; Mice, Transgenic; MicroRNAs; Neoplasm Invasiveness; Neoplasm Metastasis; Oncogene Proteins - biosynthesis; p53 Protein; Phenotype; Phenotypes; Proteins; Simian virus 40; Transgenic mice; Tumorigenesis; Tumors; Viruses; United States > US; Pittsburgh Pennsylvania
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/sj.onc.1209046

DNA tumor viruses such as simian virus 40 (SV40) express dominant acting oncoproteins that exert their effects by associating with key cellular targets and altering the signaling pathways they govern. Thus, tumor viruses have proved to be invaluable aids in identifying proteins that participate in tumorigenesis, and in understanding the molecular basis for the transformed phenotype. The roles played by the SV40-encoded 708 amino-acid large T antigen (T antigen), and 174 amino acid small T antigen (t antigen), in transformation have been examined extensively. These studies have firmly established that large T antigen's inhibition of the p53 and Rb-family of tumor suppressors and small T antigen's action on the pp2A phosphatase, are important for SV40-induced transformation. It is not yet clear if the Rb, p53 and pp2A proteins are the only targets through which SV40 transforms cells, or whether additional targets await discovery. Finally, expression of SV40 oncoproteins in transgenic mice results in effects ranging from hyperplasia to invasive carcinoma accompanied by metastasis, depending on the tissue in which they are expressed. Thus, the consequences of SV40 action on these targets depend on the cell type being studied. The identification of additional cellular targets important for transformation, and understanding the molecular basis for the cell type-specific action of the viral T antigens are two important areas through which SV40 will continue to contribute to our understanding of cancer.