Stemness-associated marker expression following hyperbaric oxygen therapy in a DMBA-induced epithelial ovarian cancer model

Abstract

Epithelial ovarian cancer (EOC) is one of the most lethal gynecologic malignancies and is commonly associated with metastasis, recurrence, and chemotherapy resistance. Ovarian cancer stem cells (OCSCs) are thought to contribute to tumor formation, metastatic progression, treatment resistance, and recurrent disease through their ability to survive under stressful microenvironmental conditions. Hyperbaric oxygen therapy (HBOT) may influence tumor oxygenation and oxidative stress; however, its effects on ovarian cancer stemness remain unclear. The aim of this study was to evaluate the effects of HBOT on the expression profile of OCSC markers in a 7,12-dimethylbenz[a]anthracene (DMBA)-induced epithelial ovarian cancer model. This experimental post-test-only control group study included 30 female Wistar rats randomly allocated into a healthy control group, a DMBA-induced epithelial ovarian cancer group without HBOT, and a DMBA-induced epithelial ovarian cancer treated with HBOT group. HBOT was administered using 100% oxygen at 1.7 atmospheres absolute. The expression of CD44, CD133, and aldehyde dehydrogenase 1 (ALDH1) was assessed immunohistochemically using H-score analysis. Overall group differences were assessed using Kruskal–Wallis tests with Dunn–Bonferroni post hoc comparisons; inter-marker relationships and expression profiles were evaluated using Spearman correlation and principal component analysis (PCA), respectively. CD44 expression differed significantly among groups (p=0.004), and post hoc analysis showed lower CD44 expression in the HBOT-treated EOC group than in the healthy group (p=0.015) and untreated EOC group (p=0.017). CD133 expression was also significantly different among groups (p=0.032), with post hoc analysis showing higher expression in the HBOT-treated EOC group than in the healthy group (p=0.048), and no significant difference was observed between the untreated EOC and HBOT-treated EOC groups. ALDH1 expression did not differ significantly among groups (p=0.877). A strong positive correlation was observed between CD133 and ALDH1 expression (r=0.70, p<0.001). PCA demonstrated partial separation of the HBOT-treated group, suggesting changes in the overall stemness-associated expression profile. These findings suggest that HBOT may be associated with altered stemness-associated marker patterns in the DMBA-induced EOC model, although the underlying mechanisms and functional relevance require further validation.