Study On Gastric Carcinoma And Mdm2, P53 And P21 Gene Abnormality

Objective To understand p53 gene mutation, the expression of mdm2, p53 and p21 protein in gastric carcinomas and corresponding adjacent tissues of gastric carcinoma. To analyse the potential pathogenic role of mdm2, p53 and p21 gene abnormality in the genesis and development of gastric carcinoma.Methods p53 gene mutation in exon 5～8 was tested by PCR-SSCP assay, mdm2,p53 and p21 protein expression were tested by the immunohistochemistry in 58 gastric carcinomas and corresponding adjacent tissues.Results①p53 immunoreactivity was detected in 50 of 58 gastric carcinomas and absent in 58 corresponding adjacent normal tissues. There were significant difference between the two groups(x~2=50.0, P=0.0000).②p21 immunoreactivity was detected in 36 of 58 gastric carcinomas and 52 of 58 corresponding adjacent normal tissues. There were significant difference between the two groups(x~2=12.5, P=0.0004).③mdm2 immunoreactivity was detected in 17 of 58 gastric carcinomas and absent in 58 corresponding adjacent normal tissues. There were significant difference between the two groups (x~2=15.059, P=0.0001).④There was significant correlation between mdm2 expression and p53 overexpression (x~2=11.1839, P=0.0008, r=0.4391 ) ,but there was no significant correlation between p21 and p53 expression(x~2=1.3228, P=0.2501, r=0.2025).⑤p53 gene mutation was found in only 2 cases of gastric carcinomas and both were exon 5. No p53 gene mutation was detected in 58 corresponding adjacent tissues.Conclusion①The abnomal expression of mdm2,p53 and p21 protein is related with the oncogenesis of gastric carcinoma.②p53 protein expression and overexpression are common in gastric carcinoma, but p53 protein abnormal accumulation might not result from p53 gene mutation.③The co-expression positive rate of p21 and p53 was high, but there was no significant correlation between p21 and p53 expression,suggesting that expression of p21 protein was induced by p53-dependent pathway as well as p53-independent pathway.④The expression of mdm2 was significantly associated with high levels of p53 protein,suggesting that mdm2 protein may play an important role in the pathogenesis of gastric carcinoma through suppressing the function of wild type p53 protein.