Comprehensive analysis of differentially expressed circRNAs revealed a ceRNA network in pancreatic ductaladenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies. However, the molecular mechanisms underlying PDAC are still not completely understood. Circular RNAs (circRNAs) are a unique class of RNA formed by special loop splicing. More and more researchers have paid attention to circRNAs. In this study, we constructed a circRNA-mediated competing endogenous RNA (ceRNA) network in PDAC. Gene ontology (GO) analysis was performed to explore circRNAs' potential roles in PDAC progression. We also constructed an up-stream transcriptional network of circRNAs' parental genes and found that many transcription factors (TFs), such as tumor protein p53 (TP53) and MYC, could regulate their expression. This study, which aimed to identify differentially expressed circRNAs in PDAC, suggested that circRNAs may also act as biomarkers for PDAC. We analyzed two public datasets (GSE69362 and GSE79634) to identify differentially expressed circRNAs in PDAC. Finally, we found that DExH-Box Helicase 9 (DHX9) may be a potential regulator of circRNA formation in PDAC. Genomic loci of four down-regulated circRNAs - hsa_circ_000691, hsa_circ_0049392, hsa_circ_0005203, and hsa_circ_0001626 - contained DHX9 binding sites, suggesting that they may be directly regulated by DHX9. Our study identified differentially expressed circRNAs in PDAC, suggesting that circRNAs may also act as biomarkers for PDAC. Additional investigations of function and up-stream regulation of differentially expressed circRNA in PDAC are still needed.