Quantitative study on the correlation between p53 gene mutation and its expression in endometrial carcinoma cell lines.
Mutant p53 protein is not degradated but accumulates in the nuclei. However, the relation between p53 gene mutation and quantity of p53 protein has not been clarified yet in endometrial carcinoma. We investigated the correlation between p53 gene mutation and its protein expression quantitatively using 11 cell lines of endometrial adenocarcinoma, endometrioid type and two serous-type cell lines. To examine p53 mutation, PCR-SSCP analysis in exon 5 to 8 and direct sequence were carried out. p53 expression was determined by immunocytochemistry and immunoblotting. The percentage of positive staining in the nuclei by immunocytochemistry was calculated as a labeling index (LI). The amount of p53 detected by immunoblotting was expressed as a comparative value of Ishikawa cells. Point mutation of p53 gene was detected in four of 11 (36.4%) cell lines of endometrioid adenocarcinoma, and all two of serous adenocarcinoma. There was a significant positive correlation between p53 LI and p53 values. The LI and the values of p53 were significantly higher in the mutant group than the wild one, thus showing a quantitative correlation between p53 protein expression and p53 gene mutation in endometrial carcinoma cell lines. It is plausible that immunohistochemical analysis of p53 could be qualified to be a convenient indicator of p53 gene mutation on clinical materials, if p53 LI is more than 40 (M-SD in mutant p53).