Growth Hormone Regulation of the c-myc Gene During Sex-Differentiated Rat Liver Carcinogenesis
The expression of the c-myc gene was analyzed at different stages of rat liver carcinogenesis in the resistant hepatocyte model (RH-model). During promotion of diethylnitrosamine (DEN)-initiated Wistar rats with 2-acetylaminofluorene (2-AAF) and partial hepatectomy (PH), the hepatic c-myc expression was increased in males, but not in females, from one day after PH. Continuous growth hormone (GH) infusion decreased the expression to the level in females. A higher c-myc mRNA level compared with the respective surrounding livers was observed in nodules from males isolated 6 weeks. This elevated c-myc RNA level was also seen in 8 and > 11 months after DEN treatment and in hepatomas, while in females an increased expression was noted only in > 11 month nodules and hepatomas. GH infusion to nodule bearing males decreased c-myc mRNA levels in surrounding livers, and in nodules 8 but not 11 months after DEN.
KeywordsGrowth Hormone Partial Hepatectomy Total Nucleic Acid Growth Hormone Regulation Altered Hepatic Focus
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Blanck A, Hansson T, Eriksson LC, Gustafsson J-Å (1987) Growth hormone modifies the growth rate of enzyme altered hepatic foci in male rats treated according to the resistant hepatocyte model. Carcinogenesis 8: 1585–1589.PubMedCrossRefGoogle Scholar
Blanck A, Hansson T, Gustafsson J-Å, Eriksson LC (1986) Pituitary grafts modify sex differences in liver tumor formation in the rat following initiation with diethylnitrosamine and different promotion regimens. Carcinogenesis 7: 981–985.PubMedCrossRefGoogle Scholar
Porsch Hâllstrôm I, Gustafsson J-Å, Blanck A (1989) Effects of growth hormone on the expression of c-myc
during early stages of sex-differentiated rat liver carcinogenesis in the resistant hepatocyte model. Carcinogenesis 10: 2339–2343.CrossRefGoogle Scholar
Cole MD (1986) The myc
oncogene: its role in transformation and differentiation. Ann Rev Genet 20: 361–384.PubMedCrossRefGoogle Scholar
Gu JR (1988) Molecular aspects of human hepatic carcinogenesis. Carcinogenesis 9: 697–703.PubMedCrossRefGoogle Scholar
Makino R, Hayashi K, Sato S, Sugimura T (1984) Expression of the cHa-ras
genes in rat liver tumors. Biochem Biophys Res Commun 119: 1096–1102.CrossRefGoogle Scholar
Nagy P, Evarts RP, Marsden E, Roach J, Thorgeirsson SS (1988) Cellular distribution of c-myc
transcripts during chemical hepatocarcinogenesis. Cancer Res 48: 5522–5527.PubMedGoogle Scholar
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