Expression of gamma-glutamyl transpeptidase in adult rat liver cells after transformation with SV40 virus

By the use of histochemical techniques we have shown that the transformation of rat hepatocytes with simian virus 40 resulted in a large majority of cells producing γ-glutamyl transpeptidase (γGT). Using a temperature-sensitive mutant of this virus we have shown that the precentage of cells exhibiting this enzyme in a temperature-sensitive SV40 mutant is much higher in cells grown at the permissive temperature of 33°C than at the non-permissive temperature of 40.5°C. We thus conclude that, the correlation between γGT expression and chemical or spontaneous transformation of hepatocytes, previously described by other authors, can now be extended to viral transformation and that the enzyme activity is dependent on the expression of a transformed cell phenotype.