Differential expression profiles of circRNAs in cancers: Future clinical and diagnostic perspectives

Since decades ago, circular RNAs (circRNAs) have been known for their critical role in RNA maturation, RNA transportation, epigenetic regulation, gene transcription, peptide/protein translation, and interaction with proteins to modulate their activities. At present, circRNAs are being extensively studied as oncotargets in the onset and development of several malignancies and treatment resistance by modulating various signaling pathways and cellular processes such as ubiquitination, degradation, invasion, proliferation, c-Myc oncoprotein stabilization, epithelial-mesenchymal transition, autophagy, and apoptosis. In addition, circRNAs are known to be highly conserved, have a longer life span than other RNAs, and their differential expressions are implicated in solid tumors and hematological malignancies. However, their potential diagnostic and therapeutic targets are not fully elucidated. Therefore, we sought to underline the opportunities and constraints associated with using these oncotargets in cancer therapy by outlining the functional mechanisms of circRNAs and their ectopic expression in distinct malignancies. The clinical applications of circRNAs in developing progressive markers like liquid biopsy biomarkers and for treating cancers are also prospected in this paper.