Fig. 1.

The regulation of circRNAs in cancer. a. CircRNAs function as microRNA (miRNA) sponges. b. CircRNAs bind RNA binding proteins (RBPs) as transcription regulators. c. CircRNAs remove start codons from mature mRNAs to reduce protein translation. d. CircRNA production competes with canonical pre-mRNA splicing in gene regulation. e. The translation of circRNAs is driven by N⁶-methyladenosine (m⁶A). f. CircRNAs with internal ribosome entry sites (IRESs) can be translated. g. EIciRNAs and ciRNAs promote transcription. h. Exo-circRNAs are cleared by the RES or excreted via the liver or kidneys. i. Exo-circRNAs regulate cancer immunity. j. Exo-circRNAs promote cancer metastasis