CD8A and hepatocellular carcinoma: The mechanism is that circCCAR1 prevents the ubiquitinated degradation of the PD1 protein by binding directly to PD1, thereby impairing the tumor killing capacity of CD8+ T cells702 Notably, in vitro and animal studies have shown that circRNA‐100338 promotes the invasion and metastasis of HCC cells and promotes vascular endothelial cell proliferation, angiogenesis, and which correlates with lung metastasis and reduced survival in HCC patients.63