Expression of oncogenic ras in human teratocarcinoma cells induces partial differentiation and permissiveness for human cytomegalovirus infection.

Retinoic acid (RA)-induced differentiation of human teratocarcinoma (T2) cells results in a change from a normally non-permissive phenotype for human cytomegalovirus (HCMV) infection to cells which are fully permissive. We have used this system to analyse factors associated with differentiation which may regulate HCMV gene expression. Differentiation of T2 cells results in an increase of c-ras expression. Consequently, we have introduced ras expression vectors into T2 cells. We find that, as with RA induction, transfection of T2 cells with oncogenic human Ha-ras results in cells which are permissive for HCMV infection and gene expression. However, unlike RA which induces a cessation of cell proliferation and terminal differentiation, ras transfection only appears to result in changes associated with early events in RA-induced differentiation of T2 cells.