Genome-wide profiling reveals alternative polyadenylation of mRNA in human non-small cell lung cancer

Abstract

Background: Lung cancer is the second most common cancer with an extremely poor overall survival rate. Post-transcriptional regulation of gene expression play many important roles in human cancer, and one of the potential mechanisms underlying this is alternative mRNA maturation at its 3′ untranslated regions (3′-UTRs). Methods: Cancer tissues and paired adjacent normal lung tissues from 26 patients diagnosed with non-small cell lung cancer (NSCLC) were analyzed by in vitro transcription-sequencing alternative polyadenylation sites (IVT-SAPAS). 41,773,101 reads in average were obtained from each paired sample. A potential regulation of Cleavage Stimulation Factor Subunit 2 (CSTF2) on 3′UTR length of genes was tested in H460 cells. Results: 1439 (10.26%) genes showed up-regulated expression and 1364 (9.72%) genes showed down-regulated expression in lung cancer tissue versus normal lung tissue, and shorten 3′UTR in cancer tissue was detected in cancer tissues collected from 96.2% (25/26) patients, indicating lung cancer tend to have shortened 3′UTRs of these identified genes. KEGG analysis showed 1855 genes with shorten 3′UTR were enriched in mTOR signaling, ubiquitin mediated proteolysis and RNA degradation. Knocking down CSTF2 expression in H460 cells results in 3′UTR elongation of genes that was identified to be with shortened length in cancer tissues. Conclusion: Alternative polyadenylation (APA) site-switching of 3′UTRs is prevalent in NSCLC, and CSTF2 may serve as an oncogene regulates the 3′UTR length of cancer related genes in NSCLC.