Regulated transcription of c-Ki-ras and c-myc during compensatory growth of rat liver.

We examined the transcription of six cellular oncogenes during the process of compensatory growth in rat liver after partial hepatectomy. We have previously reported that transcripts of c-rasH are elevated during regenerative growth of the liver. We now report that transcripts of c-rasK and c-myc genes are significantly elevated after partial hepatectomy, whereas transcripts of c-abl and c-src are essentially unchanged and transcripts of c-mos are undetectable in either normal or regenerating rat liver. In liver regeneration after partial hepatectomy or chemical injury, changes in c-myc transcripts occur before DNA synthesis. The elevation of c-myc and c-ras transcripts is sequential in that highest levels of c-myc transcripts were detected 12 to 18 h after partial hepatectomy, whereas the levels of c-rasH and c-rasK were maximal by 36 to 48 h. Transcripts of all three activated oncogenes returned to their basal levels by 96 h.