CircCMTM3, as a miR-3619–5p sponge, promotes the tumorigenesis of HCC through miR-3619-5p-SOX9 pathway (Hu et al., 2021).The exosomal circRNA-100,338 is highly expressed in metastatic HCC exosomes and promotes the metastasis of HCC via enhancing invasiveness and angiogenesis (Huang et al., 2020a). This evidence concerns the gene SOX9 and hepatocellular carcinoma.