title: Increased expression of the N-myc gene during normal and neoplastic rat liver growth.
abstract: The activation of N-myc and c-myc genes has been implicated in the genesis of a variety of cancers. In order to determine whether this activation is related to the process of cell growth, we examined N-myc and c-myc expression in rat hepatocytes when growth was stimulated by partial hepatectomy and in rat liver during neoplastic growth induced by diethylnitrosamine. The levels of N-myc and c-myc mRNAs, which are very low in hepatocytes from normal rats, were increased at least 20-fold within 3 h after partial hepatectomy and decreased rapidly by 6 h. A second transient peak of c-myc and N-myc mRNAs occurred around 9 and 48 h, respectively. N-myc and c-myc expressions were also induced in carcinoma nodules by diethylnitrosamine. A high level of N-myc transcript was observed in hepatocytes as early as 1 month after the carcinogen administration, whereas c-myc transcript was detected at a high level only several months later in carcinoma nodules. Our results suggest that the transient expression of N-myc and c-myc oncogenes during the prereplicative stage of liver regeneration may be associated with the entry of hepatocytes into the cell cycle, and that N-myc expression is not limited to tumors of neural characteristics as has been previously shown but is also observed in cancer from epithelial origin.
authors.affiliation: Institut de Pathologie Moléculaire, Unité Associée CNRS, Faculté de Médecine Cochin-Port-Royal, Paris, France.
authors.forename: M
authors.initials: M
authors.lastname: Corral
authors.forename: B
authors.initials: B
authors.lastname: Paris
authors.forename: C
authors.initials: C
authors.lastname: Guguen-Guillouzo
authors.forename: D
authors.initials: D
authors.lastname: Corcos
authors.forename: J
authors.initials: J
authors.lastname: Kruh
authors.forename: N
authors.initials: N
authors.lastname: Defer
mesh_terms: D000818:Animals; D002455:Cell Division; D002471:Cell Transformation, Neoplastic; D004052:Diethylnitrosamine; D005260:Female; D007700:Kinetics; D008099:Liver / Q000648:ultrastructure*; D008113:Liver Neoplasms / Q000139:chemically induced / Q000473:pathology*; D008115:Liver Regeneration; D009857:Oncogenes; D051381:Rats; D011919:Rats, Inbred Strains; D014158:Transcription, Genetic
chemical_list: D004052:Diethylnitrosamine