Transformation of Human and Murine Fibroblasts without Viral Oncoproteins

Abstract

Murine embryo fibroblasts are readily transformed by the introduction of specific combinations of oncogenes; however, the expression of those same oncogenes in human cells fails to convert such cells to tumorigenicity. Using normal human and murine embryonic fibroblasts, we show that the transformation of human cells requires several additional alterations beyond those required to transform comparable murine cells. The introduction of the c-Myc and H-RAS oncogenes in the setting of loss of p53 function efficiently transforms murine embryo fibroblasts but fails to transform human cells constitutively expressing hTERT, the catalytic subunit of telomerase. In contrast, transformation of multiple strains of human fibroblasts requires the constitutive expression of c-Myc, H-RAS, and hTERT, together with loss of function of the p53, RB, and PTEN tumor suppressor genes. These manipulations permit the development of transformed human fibroblasts with genetic alterations similar to those found associated with human cancers and define specific differences in the susceptibility of human and murine fibroblasts to experimental transformation.

ACKNOWLEDGMENTS

We thank Jason Arroyo, Kenkichi Masutomi, and Richard Possemato for helpful comments on the manuscript and all of the members of the Hahn and Cichowski laboratories for advice and encouragement.

This study was supported in part by grants from the U.S. National Cancer Institute (K01 CA94223 [W.C.H.] and PO1 CA50661 [W.C.H.])and the Doris Duke Charitable Foundation (W.C.H.).