Promoter methylation of Retinol Binding Protein 7 (RBP7) predicts worse prognosis in breast cancer patients

Breast cancer is the most common cancer among women all over the world. Genetic and epigenetic events are accumulated in breast tumorigenesis. Retinoid-binding protein7 (RBP7) is a member of the cellular retinol-binding protein (CRBP) family, which is involved in the pathogenesis of breast cancer. Previous study indicated high expression of RBP7 was significantly related to good relative percent survival in the luminal A subtype. However, promoter methylation of RBP7 and its relationship with clinicopathological features remains unclear. In order to investigate the methylation status of RBP7 in breast cancer patients. We collected and conducted MSP in a cohort of breast cancer patients. Our results showed that high expression of RBP7 correlates with better prognosis in breast cancer from TCGA database. And the MSP experiment in the breast cancer cohort indicated promoter methylation of RBP7 might be one of the reasons causing RBP7 down-regulation in breast cancer patient. Further study indicated that RBP7 methylation was found to be significantly associated with molecular status, LNM and cancer related death. Furthermore, the univariate and multivariable Cox regression analysis showed that RBP7 methylation acted as a predictor of poor survival either in the whole cohort or ER, PR, Her2 negative subtypes. Our study in conclusion indicates that promoter methylation of RBP7 may predict poor prognosis in breast cancer regardless of its molecular status.