Carcinogen-induced liver tumours of Wistar rats: absence of activated ras genes and of N-rasC.
We examined mutational activation of ras genes in rat liver preneoplasias and tumours induced by diethylnitrosamine and N-methyl-N-nitrosourea (NMU). In accordance with previous reports on H- and K-ras genes, no mutations were detected in the investigated hepatic tumours and prestages suggesting that neither mutations at codons 12, 13 and 61 of H- and N-ras nor a mutation in the last intron of the H-ras gene are involved in initiation and progression of rat hepatocellular carcinomas. In the course of this investigation we found two N-ras genes (N-rasA, N-rasB). Surprisingly N-rasC, which is present in the germ line of Fischer rats, is missing in Wistar rats. This suggests different numbers of germline N-ras genes in members of one species. Two out of eight NMU-induced liver tumours exhibited additional N-ras-related sequences of unknown origin.
Ostermayr
R
R
Institute of Pathology, University of Munich, Federal Republic of Germany.
Suchy
B
B
Rabes
H M
HM
D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D003062:Codon / Q000502:physiology; D005091:Exons / Q000502:physiology; D005786:Gene Expression Regulation / Q000235:genetics; D011905:Genes, ras / Q000235:genetics*; D007438:Introns / Q000502:physiology; D008099:Liver / Q000502:physiology; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced / Q000235:genetics*; D008297:Male; D008770:Methylnitrosourea; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains
D003062:Codon; D008770:Methylnitrosourea