Circular RNA ITCH: A novel tumor suppressor in multiple cancers

Circular RNAs (circRNAs) are a new type of endogenous noncoding RNAs with closed circular structure. Emerging evidence indicates that circRNAs play crucial roles in many biological processes by regulating linear RNA transcription, downstream gene expression and protein production. Meanwhile, recent studies have suggested that circRNAs have the potential to be oncogenic or anti-oncogenic and play vital regulatory roles in the initiation and progression of tumors. Circular RNA itchy E3 ubiquitin protein ligase (circ-ITCH), a novel circular RNA originated from several exons of ITCH and located on chromosome 20q11.22, was proved to be declined in many malignant tumors, such as melanoma and ovarian cancer, resulting in tumor occurrence and progression. This review summarizes the biogenesis, characteristics, and functions of circRNAs, as well as recent progression regarding the biological functions and potential molecular mechanisms of circ-ITCH, and future challenges in cancer research.