Circular RNAs Serve as Novel Biomarkers and Therapeutic Targets in Cancers

Circular RNAs (circRNAs) are a class of non-coding RNAs (ncRNAs) that structurally form closed loops without 5'-end cap and 3'-end poly(A) tail unlike linear RNAs. CircRNAs are widely present in eukaryotic cells with the capabilities of structural stability, high abundance and cell- /tissue-specific expression. A growing body of researches suggest that the dysregulated circRNAs are intimately relevant to the occurrence and development of cancer. In this review, we mainly discuss the differentially expressed circRNAs in cancer tissues, plasma and exosomes, which makes it possible for clinicians to use certain circRNAs as novel biomarkers for cancer diagnosis and prognosis. In particular, we primarily focus on circRNAs as potential therapeutic targets, which will provide promising applications in cancer gene therapy.