Comprehensive analysis of differential expression profiles of mRNAs and lncRNAs and identification of a 14-lncRNA prognostic signature for patients with colon adenocarcinoma.

The objective of this study was to identify potentially significant genes and long non-coding RNAs (lncRNAs) in colon cancer for a panel of lncRNA signatures that could be used as prognostic markers for colon adenocarcinoma (COAD) based on the data from The Cancer Genome Atlas (TCGA). RNA-seq V2 exon data of COAD were downloaded from the TCGA data portal for 285 tumor samples and 41 normal tissue samples adjacent to tumors. Differentially expressed mRNAs and lncRNAs were identified. A functional enrichment analysis of differentially expressed mRNAs was performed, followed by protein-protein interaction (PPI) network construction and significant module selection. Additionally, the regulatory relationships in differentially expressed mRNAs and lncRNAs were assessed, and an lncRNA-lncRNA co-regulation and functional synergistic analysis were performed. Furthermore, the risk score model and Cox regression analysis based on the expression levels of lncRNAs were used to develop a prognostic lncRNA signature. A total of 976 differentially expressed mRNAs and 169 differentially expressed lncRNAs were identified. MDFI and MEOX2 were the PPI network hubs. We found these lncRNAs to be mainly involved in vascular smooth muscle contraction and the cGMP-PKG signaling pathway. Several lncRNA-lncRNA pairs had co-regulatory relationships or functional synergistic effects, including BVES-AS1/MYLK-AS1, ADAMTS9-AS1/MYLK-AS1 and FENDRR/MYLK-AS1. The differential expression profile analysis of four candidate lncRNAs (MYLK-AS1, BVES-AS1, ADAMTS9-AS1, and FENDRR) in COAD tumors were confirmed by reverse transcription-quantitative PCR. Moreover, this study identified a 14-lncRNA signature that could predict the survival for COAD patients.