circRNA is a novel type of endogenous non-coding RNA that has gained attention from researchers for its involvement in multiple biological processes. It is reported that circRNA acts as miRNA sponge and RBP sponge to function in human diseases. For example, ciR-7 contains more than 70 selectively conserved miRNA target sites that can bind miR-7, facilitate a specific miR-7-AGO2 interaction, and suppress miR-7 activity in diseases including hepatocellular carcinoma, colorectal cancer, and diabetes.