A novel DNA methylation signature revealed GDF6 and RCC1 as potential prognostic biomarkers correlated with cell proliferation in clear cell renal cell carcinoma.

Background: Clear cell renal cell carcinoma (ccRCC) accounts for the majority (80%-90%) of renal cell carcinoma (RCC) patients at the time of diagnosis, and approximately 15% of ccRCC patients will develop distant metastasis or recurrence during their lifetime. Increasing number of studies have revealed that the aberrant DNA methylations is closely correlated with the tumorigenesis in ccRCC.

Results: In this study, we utilized a LASSO (least absolute shrinkage and selection operator) model to identify a combination of 13 probes-based DNA methylation signature that associated with the progression-free survival (PFS) of ccRCC patients. First, differentially methylated regions (CpGs) related to PFS and phenotypes were identified. Next, prognostic DNA methylation probes were selected from the differentially methylated probes (DMPs) and calculated risk scores to stratify patients with ccRCC. The performance of this signature was validated in an independent testing set using various analyses, including Kaplan-Meier analysis for PFS and receiver operating characteristic (ROC) curve analysis. Based on our 13-DNA methylation probes signature, ccRCC patients were successfully stratified into high- and low-risk groups. Combining DNA methylation signature with clinical variables such as T stage, M stage and tumor grade could further improve the accuracy of prediction. Moreover, we highlight two molecular biomarkers (RCC1 and GDF6) corresponding to our probes. Invitro experiments showed that knockdown of RCC1 or GDF6 in ccRCC cell lines reduced cell proliferation, which indicated that both biomarkers are associated with tumorigenesis.

Conclusions: The 13-probes-based DNA methylation signature has the potential to serve as an independent tool for survival outcome improvement and treatment strategy selection for ccRCC patients. In addition, our findings suggest that RCC1 and GDF6 may serve as promising markers for ccRCC.