Alteration of cellular gene expression in adenovirus transformed cells by post-transcriptional mechanisms.

We have isolated cDNA clones complementary to human mRNAs that are expressed at elevated levels in 293 cells, adenovirus-transformed human embryonic kidney cells, as compared to a normal counterpart of this cell line. Approximately 200 clones out of 100,000 that were screened were positive; 40 of these were isolated, of which 31 were determined to be unique and were further characterized. Each clone detected a mRNA that was 5 to 50 times more abundant in 293 cells than in the non-transformed HEK cell line. For several of these transcripts, the elevated expression appeared to be a function of transformation since they were also high in other human tumor cell lines. Strikingly, we have found that post-transcriptional control is largely responsible for the regulation of the abundance of these mRNAs.