Blood-based RBBP7 and RIBC1 methylation as a candidate epigenetic biomarker for ovarian cancer epigenetic markers RBBP7 and RIBC1 in ovarian cancer.

Ovarian cancer (OC) remains one of the leading causes of gynecological cancer-related mortality, with limited biomarkers for early detection and prognosis. Changes in DNA methylation-stable and detectable in blood-are potential candidates for clinical application. In our earlier genome-wide methylation study involving monozygotic twins where one had ovarian cancer and the other did not, we identified two genes, RBBP7 and RIBC1, as differentially methylated. These findings laid the groundwork for further targeted investigation. Peripheral blood methylation of RBBP7 and RIBC1 was evaluated in 387 ovarian cancer patients, 50 benign ovarian disease patients, and 100 healthy controls using a bisulfite-free, methylation-sensitive restriction enzyme (MSRE)-based qPCR assay. In this approach, DNA is divided into digested and undigested reactions, and methylation levels are calculated from Ct differences. Methylation levels differed across groups, with RBBP7 showing a clearer discriminatory pattern (p < 0.001) and associations with disease severity (p < 0.001) and CA125 levels (p = 0.05). RIBC1 also differed between ovarian cancer and healthy controls (p < 0.001) but showed no significant associations with clinicopathological parameters. RBBP7 methylation appears to be a potential candidate biomarker associated with disease characteristics and progression patterns of ovarian cancer. These findings suggest that RBBP7 methylation may have potential for integration into future multi-marker diagnostic and risk-stratification approaches, pending further validation. While RIBC1 methylation also showed differential patterns, its clinical relevance appears limited and requires further investigation. These findings support the integration of RBBP7 methylation assessment into early-stage diagnostic workflows and risk-stratification strategies for ovarian cancer, enabling more precise clinical decision-making. Future multicenter prospective studies are warranted before clinical implementation.