11- Circular RNAs in Carcinogenesis

Abstract

Circular ribonucleic acids (RNAs) are made by alternative splicing of the pre-messenger RNA (pre-mRNA), connecting a downstream splice site with an upstream splice site, thus encompassing any introns and exons in between and circularizing the molecule. Various mechanisms are involved in forming the circular RNAs employing the existing spliceosome, and this can lead to the production of different end products. The circular RNAs perform many biological functions but mainly that of mopping up cognate microRNA species stands out as being the most investigated. This function indicates a role in post-translational gene regulation. It works by influencing microRNAs, which are known to regulate their targets. This regulation occurs through two main mechanisms: inhibiting translation and causing mRNA destabilization. Such a function suggests an important role that the circRNAs can have in carcinogenesis and that aspect is explored further in the text. This review aims to explore the circularization mechanisms of RNAs and to highlight their potential functions and role in carcinogenesis. Understanding the involvement of circRNAs in cancer pathogenesis could have clinical implications in designing novel diagnostic tools, prognostic indicators and targeted therapies.