THE SIGNIFICANCE OF EXPRESSION OF MDM2,P53 AND P21～WAF1/CIP1 IN GASTRIC CARCINOMAS

Objective To investigate the expression of MDM2 and its relationship to p53 and p21WAF1/CIP1 in gastric carcinomas to evaluate their effects on development of the carcinoma. Methods lmmunohistochemical technique was used to examined the expression of MDM2, p53 and p21WAF1/CIP1 proteins. Ninety-four specimens of gastric carcinoma which were removal by surgery during 1997 and 1998 were examined. The chi-square test was used for statistical analysis. Results There was no detectable MDM2 in all 94 cases of gastric catcinoma. The positive rate of p53 and p21WAF1/CIP1 was 56.38% (53/94) and 4 1.49% (39/94) respectively. Positive substances were located in the nuclei of cancer cells. Normal mucosas adjacent to the tumors were all negative. There were three dysplasia foci neighboring tumors with p53 positive and five with p21WAF1/CIP1 positive. There was no significant correlation between p53 and p21WAF1/CIP1 expression, and no direct relationships between their expression and the clinicopatbological parameters such as gender, age, location, invasion, lymph node metastasis and histological type in the gastric carcinomas. Conclusions In all 94 cases the expression of MDM2 could not be found, actually the high positive rate of mutation type p53 protein refuse to induce the rise of MDM2. The significance of MDM2 in the development of gastric carcinoma is negligible. The mutation of inhibition gene p53 may be the key factor in the development in this group of gastric carcinoma. The overexpression of p21WAF1/CIP1 by p53-independent pathway in gastric carcinoma suggest that the proliferation of the cancer cell has lost its control by the G1 checkpoint in cell cycle.