DETECTION OF P53 PROTEIN OVEREXPRESSION AND DNA-PLOIDY ANALYSIS IN COLON-CANCER

Background/Aims: This study was designed to demonstrate the accumulati on of the mutant p53 protein in human neoplasms. The correlation of fl ow cytometric DNA ploidy pattern with p53 expression using the immunob lotting technique was also investigated. Methodology: In this study, t he occurence of p53 overexpression was analyzed in 34 cases of adenoca rcinoma of the colon by western. immunoblotting technique, using an an ti-human p53 monoclonal antibody (Do-7). The nuclear protein extract f rom human colon. tumor specimens was immunoblotted relative to protein standards of known molecular weight. Flow cytometric analysts was use d to study the DNA ploidy, pattern of the tumor cells. Results: Monocl onal antibody p53-Do 7 detected a single band of 53 KDa in 70.5% (24 o f 34) of the tumor specimens examined. Whereas, no bands were detected in the normal colon mucosa. The relation between p53 overexpression a nd the clinicopathological variable (Dukes' staging) was studied and n o significant difference in p53 overexpression between Dukes' stages B and C was found. Flow cytometric analysis revealed a higher incidence of DNA aneuploidy in 75 4b (15 of 20) of p53 positive cases compared with 64.3% (9 of 14) in the diploid tumors. Conclusion: The immunoblot ting technique can successfully detect the mutant p53 and is therefore expected to provide valuable information on the robe of p53 in the pr ocess of carcinogenesis.