IMMUNOHISTOCHEMICALLY DETECTABLE P53 AND MDM-2 ONCOPROTEIN EXPRESSIONIN COLORECTAL-CARCINOMA - PROGNOSTIC-SIGNIFICANCE

Aims-To investigate the correlation between the expression of the p53 and mdm-2 oncoproteins and to assess their prognostic value in colorec tal cancer. Methods-Using a polyclonal (CM1) and a monoclonal antibody directed against p53 and mdm-2, respectively, these oncoproteins were stained immunohistochemically in 109 colorectal adenocarcinomas. Resu lts-p53 was detected in less than 10% of tumour cells in 11 of 109 ade nocarcinomas, in 10-50% of tumour cells, in 17 of 109 adenocarcinomas, and in more than 50% of tumour cells in 32 of 109 adenocarcinomas. Ex pression of mdm-2 was detected in 22 of 109 (20%) cases investigated, of which 19 showed concomitant p53 expression. In most cases mdm-2 imm unoreactivity was strongly associated with a small proportion of p53 p ositive tumour cells. Both p53 and mdm-2 expression lacked statistical significance when correlated with common staging and grading paramete rs. Conclusions-Detection of p53 and mdm-2 oncoprotein expression, det ected using immunohistochemistry, is of no prognostic value in colorec tal cancer. However, the close correlation between mdm-2 immunoreactiv ity and the proportion of p53 positive cells provides further evidence that the mdm-2 gene product interacts with p53 protein.