c-myc amplification in pre-malignant and malignant lesions induced in rat liver by the resistant hepatocyte model.
We have investigated by restriction fragment analysis genomic abnormalities involving the c-myc gene in DNA isolated from adenomas and hepatocellular carcinomas (HCCs). Adenomas and HCCs were induced by the "resistant hepatocyte" protocol in diethylnitrosamine-initiated male F344 rats. Southern-blot analysis of EcoRI-restricted DNA from normal liver, early and late adenomas, 12 weeks (EAs) and 30 weeks (LAs) after initiation, and HCCs, showed 2 bands of 18 and 3.2 kb hybridizing with c-myc, in all tissues. c-myc amplification occurred in almost all HCCs, and in the majority of EAs and LAs. These results were confirmed by dilution analysis. c-myc amplification was also seen in adenomas and HCCs by Southern analysis with HindIII-restricted DNA, and in HCCs by differential PCR. c-myc mRNA increase occurred in all adenomas and HCCs, but it was higher in the lesions showing gene amplification. Moreover, a 13-kb DNA extraband, hybridizing with c-myc, was found in the HindIII-restricted DNA from HCCs, but not in normal liver and adenomas, and a 7.1-kb extra band was present in EcoRI-digested DNA from one LA. EcoRI-restricted DNA from some adenomas exhibited a decrease in intensity of the 18-kb fragment, and an increase in intensity of the 3.2-kb fragment. No alteration in banding pattern occurred in the beta-actin gene in adenomas. These results provide evidence of amplification and some other rearrangements involving the c-myc gene, in pre-malignant and malignant liver lesions, induced by the RH protocol, and suggest a role of c-myc rearrangement in the progression of adenomas to malignancy.
Istituto di Patologia Generale e Centro di Ricerche Oncologiche dell'Università di Sassari, Italy.
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Pascale
M R
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De Miglio
M R
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Muroni
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Simile
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Daino
M A
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Seddaiu
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Nufris
L
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Gaspa
L
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Deiana
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Feo
D000236:Adenoma / Q000139:chemically induced / Q000235:genetics; D000818:Animals; D015152:Blotting, Northern; D015139:Blotting, Southern; D006528:Carcinoma, Hepatocellular / Q000139:chemically induced / Q000235:genetics; D015246:Deoxyribonuclease EcoRI; D015247:Deoxyribonuclease HindIII; D004052:Diethylnitrosamine; D016259:Genes, myc / Q000235:genetics*; D008113:Liver Neoplasms / Q000139:chemically induced / Q000235:genetics*; D008297:Male; D016133:Polymerase Chain Reaction; D011230:Precancerous Conditions / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011916:Rats, Inbred F344
D012333:RNA, Messenger; D004052:Diethylnitrosamine; D015246:Deoxyribonuclease EcoRI; D015247:Deoxyribonuclease HindIII