All of oncogenes was first described as part of the genome of RNA tumor viruses and were subsequently shown to be of cellular origin. These genes termed cellular oncogenes (c-onc)-appear to have been the evolutionary progenitors of viral oncogenes. It is strongly suggested that cellular oncogenes may possess an oncogenic potential. It is important to elucidate which and how cellular oncogenes can be activated for specific tissue types of human tumors. Transforming genes in human bladder cell lines have been identified as the c-onc genes known as c-Ha-ras and c-Ki-ras of point mutation type. Recently it was found that, 10% (detection rate) of fresh human bladder tumors are related to point mutation. Therefore considering the multistep carcinogenesis in human tumor in vivo, it seems to be very important to assess the expression level of multiple c-onc genes in freshly obtained human tumor tissues. We investigated the level of gene expression of 5 c-oncogenes (c-Hr-ras, c-Ki-ras, c-myc, c-myb and r.-fps) in 17 cases of gastric adenocarcinomas (stage II: 4 cases, stage Ill: 13 cases). DNA probes using for DNA-RNA hybridization technique were all cellular oncogenes except ras-Ki-gene (v-ras Ki). The results are summarized as follows: 1) Some of gastric adenocarcinomas showed the increased expression of cfps and c-myc (10 of 17 cases, and 9 of 17 cases, respectively). Signet ring cell type of adenocarcinoms showed the high expression of c-Ha-ras. 2) The other two oncogenes, c-Ki-ras and c-myb were expressed very infrequently in the gastric adenocarcinomas. 3) The coincidence of expression of two oncogenes, such as c-myc and cfps was found in 9 of 10 cases. 4) The regional lymph node metastasis rate was below 5g in gastric adenocarcinoma cases with high expression of c-fps and c-myc (5 out of 6). 5) There is a slight decreasing tendency in cfps and c-myc expression rates from Borrmann type I to type IV. 6) There is no significant difference in c-myc and c-fps expression levels and rates between intestinal type and diffuse type of gastric adenocarcinoma classfied by Lauren's method.
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