Increased transcription of the c-myc oncogene in two methylcholanthrene-induced quail fibroblastic cell lines.
The expression of three c-onc genes (c-erb, c-myc, c-myb) was investigated in five cell lines established from fibrosarcomas induced with 20-methylcholanthrene (MCA) of Japanese quails. These cell lines showed low levels of the three c-onc genes, with the exception of two cell lines that accumulated moderate (MCAQ 1-4) and large amounts (MCAQ3-5) of c-myc RNA. Molecular cloning and restriction endonuclease analyses indicated that expression of c-myc in these two cell lines were not associated with detectable rearrangements in the c-myc locus, that the size of the c-myc transcript (2.7 kb) in MCAQ 3-5 was similar to that of the normal c-myc messenger RNAs (mRNA) and that the transcriptional activation observed in MCAQ 3-5 was not mediated by the LTR (long terminal repeat) of a proximate ALV (avian leukosis virus) provirus. Finally, when analysed with the restriction enzymes Msp I and Hpa II, the c-myc locus of MCAQ 3-5 and MCAQ 1-4 was found hypomethylated as compared with that of the other cell lines tested that show low levels of c-myc transcripts. Our results suggest that one of the ways methylcholantrene could mediate transformation is by inducing an abnormal regulation of the c-myc gene.
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D003370:Coturnix; D004247:DNA / Q000378:metabolism; D004262:DNA Restriction Enzymes; D005347:Fibroblasts / Q000187:drug effects; D005354:Fibrosarcoma / Q000139:chemically induced / Q000235:genetics / Q000473:pathology*; D008748:Methylcholanthrene / Q000633:toxicity*; D009693:Nucleic Acid Hybridization; D009857:Oncogenes; D014158:Transcription, Genetic
D008748:Methylcholanthrene; D004247:DNA; D004262:DNA Restriction Enzymes