The role of circular RNAs in pancreatic cancer: new players in tumorigenesis and potential biomarkers

Circular RNAs (circRNAs) are a newly identified class of non-coding RNAs (ncRNAs) which show different structure compared to other RNAs in terms of their covalently closed ends. To date, a huge number of circRNAs have been identified in various species and also several databases have been created for storing and providing accessibility to retrieved data on identified circRNAs. They are produced by back-splicing from mainly protein coding genes. Same to other ncRNAs, circRNAs have been found to play role in gene regulation via interaction with other biomolecules like nucleic acids, proteins and microRNAs (miRNAs). They are involved in different physiological processes like vascular functions, brain and embryonic development, regulation of metabolism, cell cycle control and response to cellular stress. Dysregulation of circRNAs have been associated with many types of human diseases like cardiovascular diseases, immune diseases, neurologic diseases, diabetes and particularly various types of cancer. In this review, we have a look to the cellular experiments conducted on the role of circRNAs in the pancreatic cancer. Two cellular behaviors of two categories of circRNAs including up-regulated and down-regulated transcripts have been reviewed in pancreatic cancer. Furthermore, their potential application in diagnosis and prognosis of pancreatic cancer has been summarized. The results show circRNAs are potential diagnostic and prognostic biomarkers of pancreatic cancer.