title: Cell cycle deregulation in liver lesions of rats with and without genetic predisposition to hepatocarcinogenesis.
abstract: Preneoplastic and neoplastic hepatocytes undergo c-Myc up-regulation and overgrowth in rats genetically susceptible to hepatocarcinogenesis, but not in resistant rats. Because c-Myc regulates the pRb-E2F pathway, we evaluated cell cycle gene expression in neoplastic nodules and hepatocellular carcinomas (HCCs), induced by initiation/selection (IS) protocols 40 and 70 weeks after diethylnitrosamine treatment, in susceptible Fisher 344 (F344) rats, and resistant Wistar and Brown Norway (BN) rats. No interstrain differences in gene expression occurred in normal liver. Overexpression of c-myc, Cyclins D1, E, and A, and E2F1 genes, at messenger RNA (mRNA) and protein levels, rise in Cyclin D1-CDK4, Cyclin E-CDK2, and E2F1-DP1 complexes, and pRb hyperphosphorylation occurred in nodules and HCCs of F344 rats. Expression of Cdk4, Cdk2, p16(INK4A), and p27(KIP1) did not change. In nodules and/or HCCs of Wistar and BN rats, low or no increases in c-myc, Cyclins D1, E, and A, and E2F1 expression, and Cyclin-CDKs complex formation were associated with p16(INK4A) overexpression and pRb hypophosphorylation. In conclusion, these results suggest deregulation of G1 and S phases in liver lesions of susceptible rats and block of G1-S transition in lesions of resistant strains, which explains their low progression capacity.
authors.affiliation: Department of Biomedical Sciences, Division of Experimental Pathology and Oncology, University of Sassari, Sassari, Italy.
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Pascale
authors.forename: Maria M
authors.initials: MM
authors.lastname: Simile
authors.forename: Maria R
authors.initials: MR
authors.lastname: De Miglio
authors.forename: Maria R
authors.initials: MR
authors.lastname: Muroni
authors.forename: Diego F
authors.initials: DF
authors.lastname: Calvisi
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Asara
authors.forename: Daniela
authors.initials: D
authors.lastname: Casabona
authors.forename: Maddalena
authors.initials: M
authors.lastname: Frau
authors.forename: Maria A
authors.initials: MA
authors.lastname: Seddaiu
authors.forename: Francesco
authors.initials: F
authors.lastname: Feo
mesh_terms: D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology*; D018797:Cell Cycle Proteins / Q000378:metabolism; D019925:Cyclin A / Q000235:genetics; D019938:Cyclin D1 / Q000235:genetics; D019927:Cyclin E / Q000235:genetics; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics; D004268:DNA-Binding Proteins; D004195:Disease Models, Animal; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; D016193:G1 Phase / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D020022:Genetic Predisposition to Disease; D008099:Liver / Q000473:pathology*; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology*; D008297:Male; D010766:Phosphorylation; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D051381:Rats; D011914:Rats, Inbred BN; D011916:Rats, Inbred F344; D017208:Rats, Wistar; D016160:Retinoblastoma Protein / Q000378:metabolism; D016196:S Phase / Q000235:genetics; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D019925:Cyclin A; D019927:Cyclin E; D019941:Cyclin-Dependent Kinase Inhibitor p16; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; D050687:E2F1 Transcription Factor; C493755:E2f1 protein, rat; D016271:Proto-Oncogene Proteins c-myc; D016160:Retinoblastoma Protein; D050680:Transcription Factor DP1; D014157:Transcription Factors; D019938:Cyclin D1