Fig. 3

Biological functions of circRNAs in colorectal cancer. a | circRNAs regulate the cell cycle by inducing cell cycle arrest (e.g., circNOL10) or promoting cell cycle progression (e.g., circ-MDM2). b | circRNAs also regulate cell apoptosis by inducing (e.g., circCDYL) or inhibiting (e.g., circVAPA) cell apoptosis. c | Some circRNAs modulate the epithelial-mesenchymal transition (EMT) process by promoting (e.g., circPTK2) or inhibiting (e.g., circSMAD7) EMT; E-cad = E-cadherin, N-cad = N-cadherin. d | A few circRNAs have been shown to promote tumor angiogenesis and metastasis (e.g., circ-001971), while other circRNAs inhibit tumor metastasis (e.g., circ-FBXW7). e | Several circRNAs promote the self-renewal of colorectal cancer stem cells (CSCs) or tumor-initiating cells (TICs) and maintain the stemness of CRC cells (e.g., circLgr4 and circAGFG1). f | Finally, certain circRNAs modulate fatty acid β-oxidation (FAO) or glycolysis in CRC cells, resulting in profound changes in cellular lipid storage and increased cell growth (e.g., circACC1); Glu = glucose, Pyr = pyruvate, Lac = lactate, A-CoA = acetyl-CoA, P-CoA = palmitoyl CoA, FA = fatty acid, LDH = lactate dehydrogenase, PDH = pyruvate dehydrogenase, CPT = carnitine palmitoyltransferase, TCA cycle = tricarboxylic acid cycle