Introduction: The modification of p53 protein by phosphorylation plays an important role in its stabilization and the regulation of its biological properties. The study investigated the expression of p53 protein phosphorylated at serine 20 (Ser20) and Ser392 and the association between clinicopathological parameters of ovarian neoplasms with respect to p53 protein overexpression.

Methods: p53 protein expression was evaluated on tissues from malignant and benign ovarian tumors. Protein expression was measured in a subset of the specimens using immunohistochemistry.

Results: The correlation between p53 protein overexpression and p53-Ser392 phosphorylation was found in ovarian carcinomas (P = 0.001, r = +0.27). In the total group of ovarian carcinomas, significant differences were observed in p53 protein overexpression between well (G1) and poor (G3) tumor grades (P = 0.005) and between serous and endometrioid types of tumor (P = 0.04), whereas p53-Ser20 phosphorylation was associated with advanced International Federation of Gynecology and Obstetrics stage (P = 0.004) and high tumor grade (P = 0.02). In p53-positive ovarian carcinomas, p53-Ser392 phosphorylation was associated with advanced tumor stage (P = 0.02) and high tumor grade (P = 0.049). p53-Ser20 phosphorylation was associated with low tumor grade of p53-positive ovarian carcinomas (P = 0.02) and with high tumor grade of p53-negative ovarian carcinomas (P = 0.02).

Conclusions: These results revealed that p53 phosphorylation at Ser20 and Ser392 is an early event in ovarian tumor development. The authors suggest that the expression of p53 protein phosphorylated at Ser20 and Ser392 in ovarian carcinomas determines their individual clinical features depending on p53 protein status and may be useful biological biomarkers characterizing their behavior.