[Expression and mutation of p53 and H-ras genes in the carcinogenesis and development of gastric adenocarcinoma induced by MNNG in rats].
OBJECTIVE
To investigate the effect of p53 and H-ras genes in the carcinogenesis of and development of gastric cancer induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Wistar rats.


METHODS
The expression of p53 and H-ras genes in normal mucosa, precancerous lesions and induced-cancers were studied immunohistochemically. DNA isolated from the precancerous lesion and tumors were analysed by PCR-SSCP for exon 5-8 of p53 gene and exon 1 and 2 of H-ras gene.


RESULTS
p53 protein were detected in 50% (20/40) of the gastric cancers studied, but not in the precancerous lesion, while p21 ras protein seen in 23% (9/40) of the gastric cancers and 44% (23/52) of the precancerous lesions. p53 gene mutations were detected in 45% (18/40) of the cancers and none in the precancerous lesions by PCR-SSCP. H-ras gene mutation was not found in either the cancers or the precancerous lesions.


CONCLUSIONS
The activation of ras gene is an early event and may be involved in the carcinogenesis of gastric cancer induced by MNNG. Inactivation of p53 gene may influence the development of the cancer.
Meng
Z
Z
Department of Pathology, Beijing Medical University, Beijing 100083.
Lei
D
D
Wang
J
J
D000230:Adenocarcinoma / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D015870:Gene Expression; D016158:Genes, p53; D011905:Genes, ras; D008297:Male; D008769:Methylnitronitrosoguanidine; D009154:Mutation; D016283:Proto-Oncogene Proteins p21(ras) / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D013274:Stomach Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000378:metabolism; D016159:Tumor Suppressor Protein p53 / Q000096:biosynthesis
D016159:Tumor Suppressor Protein p53; D008769:Methylnitronitrosoguanidine; D016283:Proto-Oncogene Proteins p21(ras)