Expression of mdm2 and p53 in epithelial neoplasms of the colorectum.

AIMS To evaluate the respective roles of mdm2 (murine double minute 2) and p53 in the development of colorectal carcinoma. METHODS Formalin fixed, paraffin wax embedded tissues from 72 sporadic adenomas and 55 carcinomas were investigated by means of immunohistochemistry for mdm2 and p53. RESULTS mdm2 was expressed weakly in 17 of 72 (23.6%) adenomas and in 14 of 55 (25.4%) carcinomas. p53 was expressed in 19 of 72 (26.4%) adenomas and in 23 of 55 (41.8%) carcinomas. Four adenomas and five carcinomas showed positive staining for both proteins. Overexpression of p53 in adenomas was associated with moderate and severe dysplasia but not with tumour size. No associations were found between the expression of mdm2 and either the degree of dysplasia or tumour size. In carcinomas, neither the expression of p53 nor mdm2 correlated with Dukes's stage, metastasis, or differentiation. No associations were found between the expression of p53 and mdm2 in either adenomas or carcinomas. CONCLUSIONS Although mdm2 has been reported to be an oncogene, it does not appear to play a major role in the development of colorectal carcinoma.