ALTERATION IN THE CODING POTENTIAL AND EXPRESSION OF H-RAS IN HUMAN CYTOMEGALOVIRUS-TRANSFORMED CELLS

CMV-transformed cell lines demonstrated a greater level of H-ras RNA (7.5- to 9.5-fold) relative to the level for H-ras in parental cells. Nuclear run off assays showed that the RNA levels for the H-ras gene were regulated at the level of transcriptional initiation. The increased RNA levels for H-ras correlated with the level of p21(ras)Val-12 in transformed cells, while p21(ras)Val-12 was below the level of detection in nontransformed cells using Western blot analysis. In addition, an activating mutation was identified in both alleles of the first exon, codon 12 of H-ras resulting in a G:C to T:A transversion in all transformed cell lines examined in this study. These results suggest that the mutated H-ras may be one of the components by which an oncogenic phenotype is maintained in these CMV-transformed cells.