c-fos regulation in untransformed as compared to transformed Balb/c 3T3 fibroblasts.
The regulation of c-fos expression was studied in the untransformed A31 Balb/c 3T3 mouse fibroblast cell line and in the derivative benzo(a)pyrene (BPA31), dimethylbenz(a)anthracene (DA31) and the Kirsten sarcoma virus (KA31) transformed cell lines. The peak induced c-fos RNA levels varied by about 20-fold among the cell lines. Differences in the peak level of c-fos RNA were due primarily to differences in the de novo transcriptional rate rather than in the stability of the message. Superinduction of 6-12x occurred after combined cycloheximide and phorbol ester treatment in the 4 cell lines. Superinduction of 20x in the untransformed A31 cells but only 1-3x in the transformed cells occurred when cycloheximidine and 10% serum were used. Superinduction of 5x in the A31 cells and of 1-2x in the transformed cells was found using cycloheximide and A23187. The data suggest the possibility that a labile protein which degrades the c-fos RNA is stabilized or increased in the transformed cells.
Division of Medical Oncology, Harbor-UCLA Medical Center, Torrance 90509.
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D000818:Animals; D002461:Cell Line, Transformed; D003513:Cycloheximide / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects; D015151:Immunoblotting; D051379:Mice; D008807:Mice, Inbred BALB C; D011493:Protein Kinase C / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D016760:Proto-Oncogene Proteins c-fos; D012313:RNA / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects
D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos; D012313:RNA; D003513:Cycloheximide; D011493:Protein Kinase C