Immunohistochemical expression of CD44v9 and 8-OHdG in ovarian endometrioma and the benign endometriotic lesions adjacent to clear cell carcinoma

Aim: Expression of CD44 variant isoforms (CD44v) promotes the synthesis of reduced glutathione and contributes to reactive oxygen species defense through up-regulation of the intracellular antioxidant. The aim of the study was to investigate the expression of CD44v9 and oxidative DNA damage marker, 8-OHdG, in benign ovarian endometrioma (OE) and OE harboring clear cell carcinomas (CCC). Methods: A retrospective study was performed at the Department of Gynecology, Nara Medical University hospital from January 2006 to December 2012. Patients with histologically confirmed benign OE (n = 27) and OE harboring areas of CCC (n = 8) were selected. Tissue samples were immunohistochemically analyzed for the presence of CD44v9 and 8-OHdG using avidin-biotin complex method. Results: CD44v9 was located on the cell membrane of endometriotic epithelial cells and expressed in 88.9% (24/27) of benign OE tissues. Only 25.0% (2/8) of benign endometriotic lesions adjacent to CCC was found to stain weakly for CD44v9. Percentage of CD44v9 positive cells was 68.5 ± 20.2% (mean ± standard deviation) of benign OE, 16.7 ± 16.5% of CCC endometriotic tissue (P < 0.001). Compared to benign OE, CCC endometriotic tissue showed a significant increase in the proportion of 8-OHdG expression (77.3 ± 22.5% vs 94.9 ± 3.0%, P = 0.049). A significant negative correlation was observed between CD44v9 status and 8-OHdG nuclear expression (r = −0.458, P = 0.006). Conclusion: Alterations in CD44v9 and 8-OHdG may be associated with malignant transformation of benign OE.