TGF-β regulates hepatocellular carcinoma progression by inducing Treg cell polarization.

BACKGROUND/AIMS TGF-β plays a key role in the progression of various tumors. The main objective of our study was to investigate whether TGF-β is able to regulate N-nitrosodiethylamine (DEN)-induced hepatocellular carcinoma (HCC) progression in a mouse model by inducing Treg cell polarization. METHODS HCC progression, TGF-β and Foxp3 expression levels, serum TGF-β, IL10 and GP73 levels as well as percentage of Treg cells were analyzed in healthy, HCC and HCC+SM-16 mouse groups. The effect of TGF-β on Treg cell polarization in vitro was measured by flow cytometric analysis. The expression of TGF-β and IL10 was identified by IHC in HCC patients and the correlation between TGF-β and IL10 was also assessed. RESULTS TGF-β expression is up-regulated in a DEN-induced HCC mouse model. TGF-β can promote the differentiation of Foxp3(+)CD4(+) T cells (Treg cells) in vitro. However, blocking the TGF-β pathway with a specific TGF-β receptor inhibitor, SM-16, reduced HCC progression and the percentage of Treg cells in liver tissue. The correlation between TGF-β and Treg cells was also confirmed in HCC patients and the expression of both TGF-β and IL-10 was shown to be associated with HCC progression. CONCLUSION TGF-β is necessary for HCC progression, acting by inducing Treg cell polarization.