Demonstration of ras and p53 gene mutations in carcinomas in the forestomach and intestine and soft tissue sarcomas induced by N-methyl-N-nitrosourea in the rat.
The presence of ras family and p53 gene mutations in rat forestomach, intestine and liver tumors and soft tissue sarcomas induced by N-methyl-N-nitrosourea (MNU) was examined using polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) followed by direct sequencing analysis. In the forestomach squamous cell carcinomas (SCC), Ha-ras and p53 mutations were detected in 2 (40%) and 4 (80%) of 5 cases, respectively. The figures for Ki-ras and p53 gene mutations in adenocarcinomas of the large and small intestines were 3 (18.8%) and 5 (31.3%) of 16 cases. Soft tissue sarcomas in different sites were found to have mutations of Ki-ras in 7 (23.3%) and of p53 in 9 (30%) of 30 cases. One forestomach SCC and 2 soft tissue sarcomas had double p53 mutations in different exons. Single cases of forestomach SCC and intestinal adenocarcinoma had mutations in both Ki-ras and p53 genes. No mutations were found in counterpart benign tumors or hepatocellular adenomas. The p53 mutation spectrum revealed preferential clustering within exon 8 for the forestomach SCCs, and exons 5 and 8 for the intestinal adenocarcinomas, whereas the distribution was evenly spread through exons 5 to 8 in soft tissue sarcomas. All the detected ras or p53 mutations were G:C to A:T transitions. These results indicate firstly that specific Ki-ras, Ha-ras and p53 gene mutations in MNU-induced lesions are related to particular alkylation sites (G:C to A:T transitions) and secondly, although not essential, Ki-ras, Ha-ras or p53 gene mutations may be involved in the progression stage of forestomach, intestine and soft tissue neoplasms induced by MNU.
Matsumoto
K
K
Second Department of Pathology, Fujita Health University School of Medicine, Toyoake.
Iwase
T
T
Hirono
I
I
Nishida
Y
Y
Iwahori
Y
Y
Hori
T
T
Asamoto
M
M
Takasuka
N
N
Kim
D J
DJ
Ushijima
T
T
Nagao
M
M
Tsuda
H
H
D000230:Adenocarcinoma / Q000139:chemically induced / Q000235:genetics; D000236:Adenoma / Q000139:chemically induced / Q000235:genetics; D000818:Animals; D002273:Carcinogens; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced / Q000235:genetics; D016158:Genes, p53 / Q000235:genetics*; D011905:Genes, ras / Q000235:genetics*; D007414:Intestinal Neoplasms / Q000139:chemically induced / Q000235:genetics*; D008114:Liver Neoplasms, Experimental / Q000139:chemically induced / Q000235:genetics*; D008297:Male; D008770:Methylnitrosourea; D009374:Neoplasms, Experimental / Q000139:chemically induced / Q000235:genetics; D010212:Papilloma / Q000139:chemically induced / Q000235:genetics; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D051381:Rats; D011916:Rats, Inbred F344; D012513:Sarcoma, Experimental / Q000139:chemically induced / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013274:Stomach Neoplasms / Q000139:chemically induced / Q000235:genetics*
D002273:Carcinogens; D008770:Methylnitrosourea