Exp Mol Med.  2001 Dec;33(4):293-298.

Immortalization of human embryonic fibroblasts by overexpression of c-myc and simian virus 40 large T antigen

Affiliations
  • 1Department of Biochemistry, College of Medicine, Hallym University, Chunchon, Kangwon-do, Korea.

Abstract

SV40 large T antigen, a viral oncoprotein, is known to immortalize human diploid fibroblast by soaking up cellular RB and p53, but its frequency is extremely low. Additional genetic alteration is necessary for single-step immortalization. We attempted to find out what this alteration is by overexpressing cellular signal mediator genes; c-myc and cyclin D frequently amplified in many cancer cells. Overexpression of cyclin D did not affect the immortalization, but, overexpression of c-myc along with T antigen could immortalize normal human diploid fibroblast. Several cellular markers tested during immortalization process showed that p21, a cyclin-dependent kinase inhibitor and a marker of cellular senescence, disappeared in the life span-extended cells by T antigen and in the immortalized cells by c-myc. p21 was, however, elevated in the senescent cells and in the cells of crisis. Interestingly, p16 was upregulated whenever T antigen is overexpressed. Telomerase activity was also activated only in the immortalized cells. These results suggest that overexpression of c-myc contributes to immortalization of human diploid fibroblast by activating telomerase activity and suppressing p21 activity.

Keyword

immortalization; human embryonic fibroblasts; SV40 large T antigen; telomerase

MeSH Terms

Antigens, Polyomavirus Transforming/genetics/*metabolism
Biological Markers
Cell Aging/*genetics
Cell Transformation, Viral
Cells, Cultured
Cyclins/metabolism
Diploidy
Fibroblasts/*metabolism
Genes, myc/*genetics
Human
Protein p16/metabolism
Simian virus 40/genetics
Support, Non-U.S. Gov't
Telomerase/metabolism
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