RESUMO
p53 gene mutation (exon4 , 5 , 6 . 7 . 8 and intron6) in gastric cancer and precancerous le- sions and p53 gene (exon4 and intron6) .APC gene deletion in gastric carcinomas were studied by PCR/ SSCP and PCR/RFLP. Results showed: mutation rate of p53 in intestinal metaplasia ,dysplasia and gas- tric carcinoma was 37. 5% (3/8) ,42. 1 % (8/19) , 53. 3% (16/30) ,respectively. There was significant dif- ference between groups of metaplasia、dysplasia、cancer and that of normal control. We found there were no exon8 mutation in metaplasia and dysplasia , but 4 cases in cancer group. lt is suggestted that exon8 mutation occurs at the late stage of gastric cancer , but exon 5 , 6 , 7 mutation occur in the course of pre- cancerous lesions to cancer. Loss of heterozygosity (LOH) of exon4 . intron6 . APC was 47. 4 % ( 9/19) . 8. 7%C2/23).16. 7%(3/18) ,respectively. There are some relationship between LOH of exon4 and poor- ly differentiation , lymph node metastas , depth of invasion. LOH of exon4 may be one of prognostic marker of gastric cancer. We concluded that p53 gene mutation is an early event and perhaps has syner- gism with ras oncogene in gastric carcinogenesis