Functionally, the functional assays showed that TDO2 overexpression blocked the effects of silencing circZNF566 on the suppression of HCC cell mobility, migration, invasion, and proliferation, while downregulation of TDO2 mitigated the circZNF566-induced increases these abilities (Fig. 7f, g, Supplementary Fig. S6d, 6e). This evidence concerns the gene TDO2 and hepatocellular carcinoma.