A novel epigenetic signature for predicting the prognosis of pancreatic ductal adenocarcinoma

Abstract

Background Aberrant DNA methylation is often involved in carcinogenesis. This study is designed to establish an epigenetic signature to predict overall survival (OS) of pancreatic ductal adenocarcinoma (PDAC). Methods DNA methylation and RNA-seq data of PDAC patients were downloaded from the Cancer Genome Atlas database, Genotype-Tissue Expression (GTEx), and International Cancer Genome Consortium (ICGC) database. Methylation-related differentially expressed genes (DEGs) were identified using an R package MethylMix. Epigenetic signature and nomogram were established by the LASSO and multivariate Cox regression analysis, respectively. In addition, a joint survival analysis of the gene expression and methylation was performed to identify potential prognostic factors for patients with PDAC. Results There were a total of 56 methylation-related DEGs by MethylMix criteria. After LASSO Cox regression analysis, we developed an epigenetic signature composed of five genes according to their methylation level. The signature was able to divide patients into high-risk and low-risk groups, and the OS between the high-and low-risk groups was more significantly different in both training and validation cohort. The signature is independent of clinicopathological variables and indicated better predictive power. Moreover, we developed a novel prognostic nomogram that combines risk scores with three clinicopathological factors. The joint survival analysis of gene expression and methylation revealed that 24 genes could be independent prognostic factors for OS in PDAC. Conclusions The qualitative signature and nomogram that predict OS at the individualized level and guide therapy for patients with PDAC.