[Gene expression in gastric carcinoma tissues]

In gastric cancer, the expression of c-myc protein and mRNA were investigated to determine the mechanism of inappropriate expression of c-myc gene. Correlation between clinical findings and the gene was also studied. Forty-six lesions of 43 patients were investigated by immunohistochemical staining technique. The expression of c-myc mRNA in the small fresh tissues of the same patients was detected by Northern blot hybridization. Results were as follows: 1) c-myc protein was detected in 20 lesions. The expression of c-myc protein was not differed in histological types ans stages of the lesions. 2) The level of c-myc mRNA expression was increased. In 34 cancer lesions than normal mucosa of the same patients. The overexpression of c-myc mRNA in the cancer lesion was more frequently found in early-stage cancer than in advanced-stage cancer. However, no difference was seen in histological types. 3) c-myc protein expression was correlated with mRNA overexpression. 4) In early-stage cancer, the rate of the lesions found to express excess c-myc protein was not so frequent as that of mRNA overexpression. In conclusion, c-myc mRNA overexpression was thought to cause inappropriate protein expression in gastric cancer and c-myc gene overexpression might happen already in the early-stage of gastric cancer suggesting it had a role in carcinogenesis.