Non-coding RNA in cancer

Abstract

Majority of the human genome is transcribed to RNAs that do not encode proteins. These non-coding RNAs (ncRNAs) play crucial roles in regulating the initiation and progression of various cancers. Given the importance of the ncRNAs, the roles of ncRNAs in cancers have been reviewed elsewhere. Thus, in this review, we mainly focus on the recent studies of the function, regulatory mechanism and therapeutic potential of the ncRNAs including microRNA (miRNA), long ncRNA (lncRNA), circular RNA (circRNA) and PIWI interacting RNA (piRNA), in different type of cancers.

Keywords: cancer; circular RNA; long non-coding RNA; microRNA; non-coding RNA; piwi RNA.

Figure 1. The biogenesis and effector machineries of miRNAs

miRNAs are transcribed as pri-miRNAs by RNA polymerase II. Following processing by the Drosha complex, pre-miRNAs are exported to the cytoplasma by exportin 5 (XPO5). Mature miRNAs are produced by Dicer and TAR RNA-binding protein 2 (TARBP2)-mediated processing and loaded into the RISC. miRNAs function through degrading mRNA or repressing translation to regulate cancer.

Figure 2. The biogenesis and effector machineries of lncRNAs

LncRNAs are transcribed by RNA polymerase II. LncRNAs function as guide molecules to recruit factors for chromatin remodeling, as decoys to hinder transcriptional factors from the promoter of target gene, as sponges of associated miRNA to prevent degradation of target gene, or as scaffolds to facilitate interaction of associated proteins.

Figure 3. The biogenesis and effector machineries of circRNAs

circRNAs are transcribed by RNA polymerase II and cyclized by backsplicing. circRNAs function as scaffolds to facilitate interaction of associated proteins, or as miRNA sponges to prevent degradation of target gene.