CCL20‐CCR6 Cytokine Network Facilitate Treg Activity in Advanced Grades and Metastatic Variants of Hepatocellular Carcinoma

Tumour immunity regulates tumour restriction to the site of occurrence. Failure of this balance facilitates tumour spread beyond the primary organ of origin. Tregs are known to be recruited in infections, including viral infections like hepatitis B and hepatitis C. Thus, they form a continuum of initial viral infection, an environment of immune suppression by recruitment of Tregs, intrinsic viral‐mediated nuclear transformation and carcinogenesis, and thereafter worsening of progress, including metastasis due to the Tregs suppressing the cell‐mediated destruction of tumour cells. In this study, we obtained advanced grades of hepatocellular carcinoma (HCC) and examined the cytokines that is potentially known to recruit Tregs. We examined the expression of CCL20, the cytokine that recruits Tregs. We isolated Tregs from HCC samples and examined expression of CCR6, the receptor for CCL20 and compared expression in control tissues obtained mainly from subjects with cirrhosis, but no evidence of cancer. The findings of this study indicate that mRNA expression of CCL20 is significantly enhanced, along with expression of mRNA for the cytokines IL17 and IL6. Furthermore, tissue expression of Gamma‐interferon was reduced in HCC. When Tregs were isolated from the liver cancer samples, the expression of CCR6, the only and specific receptor for CCL20, was upregulated in the cancer tissue derived Tregs. Furthermore, STAT3 levels were significantly increased in these tumour‐derived Tregs. This study demonstrates that immune evasion mechanisms are operant in hepatocellular carcinoma through a transcriptional network of CCL20‐IL17‐IL6 cytokines that facilitate immune suppression‐mediated cancer cell elimination and metastasis.