Expression pattern of PAX2 in hyperplastic and malignant endometrium.

Background: PAX2 is a member of paired box gene family and expressed during development of urogenital system. This study aimed to evaluate PAX2 expression pattern in hyperplastic and malignant endometrial tissues in comparison to non-pathological endometrial changes and to investigate the presence of any correlation between the PAX2 expression and tumor behavior.
Methods: The study was performed on the archival material of 121 endometrial tissues including complex hyperplasia (n = 18), complex atypical hyperplasia (n = 20), and endometrioid type adenocarcinoma (n = 47) as study groups, and proliferative endometrium (n = 21) and atrophic endometrium (n = 16) as control groups. One representative block for each case was selected for immunohistochemical evaluation. Sections with 4μm thickness were cut from the blocks and incubated with PAX2 rabbit anti-human polyclonal antibody.
Results: PAX2 nuclear staining was detected in all of the endometrial tissues. The mean percentages of PAX2 staining cells were 80.8, 96.7, 88.6, 92.7, and 99.2% with proliferative endometrium, atrophic endometrium, complex hyperplasia, complex atypical hyperplasia, and adenocarcinoma, respectively (Kruskal-Wallis; P < 0.001). The frequency of PAX2 staining increased as the pathology progressed in the manner of complex hyperplasia → complex atypical hyperplasia → adenocarcinoma. In cancer cases, there was no correlation between PAX2 expression levels and the stage, histological grade, myometrial invasion, and lymph node status.
Conclusions: PAX2 is expressed in hyperplastic and malignant endometrium as well as proliferative and atrophic endometrium. As the neoplastic lesion progresses from a premalignant state to endometrial cancer, PAX2 expression increases. These findings suggest that PAX2 may contribute to the development of endometrial cancer.