A similar manifestation was found in HCC, where exosome circCCAR1 expression was upregulated in hepatocellular carcinoma cells, which not only reduced the levels of perforin and granzyme B proteins in CD8+ T cells to promote their apoptosis, but also reduced the secretion of cytokines on their surface, causing dysfunction of CD8+T cells [106]. This evidence concerns the gene PRF1 and hepatocellular carcinoma.