Effects of 17 beta-estradiol on c-myc and c-Ha-ras expression in the liver of ovariectomized female rats.
Twenty four hours after i.p. injection of 17 beta-estradiol (E2) (500 micrograms/100 g b.w.) to ovariectomized rats, the hepatocytes [3H]-thymidine pulse-labeling index (L.I.) was significantly increased, reaching a value of 4.3 +/- 1.6 percent (i.e. much lower than 32.0 +/- 2.0 percent 24 h. after partial hepatectomy -PH-). E2-treatment was followed by an increase in liver content in c-myc transcripts, with a peak at 650 percent basal value at 8 h, very similar to that observed after PH. In contrast, E2 induced an increase in liver c-Ha-ras expression with a similar time-course evolution but markedly lower amplitude than that seen after PH. These data are consistent with a role of c-myc in proliferative competence i.e. the ability to perform the Go-G1 transition, and with a role of c-ras in further progression of the cells in the cycle.
Servais
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P
Laboratory of Cytology and Experimental Cancerology, School of Medicine, Free University of Brussels (ULB), Belgium.
Galand
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P
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006498:Hepatectomy; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D010052:Ovariectomy; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis*; D016283:Proto-Oncogene Proteins p21(ras) / Q000096:biosynthesis*; D011519:Proto-Oncogenes / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical
D016271:Proto-Oncogene Proteins c-myc; D004958:Estradiol; D016283:Proto-Oncogene Proteins p21(ras)