STUDIES ON THE HYPOMETHYLATION OF C-MYC, C-HA-RAS ONCOGENES AND HISTOPATHOLOGICAL CHANGES IN HUMAN GASTRIC-CARCINOMA

In order to study the status of DNA methylation of specific oncogenes and the relationship between them and the pathological changes in gast ric carcinoma, we analysed the methylated status of c-myc, c-Ha-ras on cogenes by Southern blot hybridization. Genomic DNA from cancerous, pa racancerous and non-cancerous areas of surgically resected specimens w ere examined in 22 cases of advanced human gastric carcinoma. Specimen s were digested by the restriction endonucleases MspI/HpaII, which are able to cleave between methylated and non-methylated cytosine at thei r nucleotide recognition site the DNA 5'-CCGG sequence, and were hybri dized with c-myc, c-Ha-ras oncogene probes. Moreover, the correspondin g pathological changes in gastric carcinoma were observed. The results showed that c-myc, c-Ha-ras oncogenes from cancerous (10/22, 5/10) an d paracancerous areas (13/22, 4/10) were hypomethylated and that there was no significant relationship between them and the histopathologica l changes.