GdCl3 suppresses the malignant potential of hepatocellular carcinoma by inhibiting the expression of CD206 in tumor-associated macrophages

In the present study, we aimed to ascertain whether there is a correlation between CD206 expression in tumor associated-macrophages (TAMs) and the prognosis of primary hepatocellular carcinomas (HCC) and we investigated the effect of GdCl3 on HCC. The expression of CD206 in HCC tumor tissues and pen-carcinoma tissues was measured using an array for liver tissues. The effects of GdCl3 on CD206 expression were examined in stimulated RAW264.7 cells. Target gene expression was evaluated by RT-PCR, western blotting and immunohistochemistry. The Transwell system was used to assess the invasiveness of HCC cells. Finally, we established a mouse model for HCC using N-nitrosodiethylamine (DEN) to determine the effect of GdCl3 on HCC. Liver tissue array analysis revealed that CD206 was highly expressed in the HCC tissues compared to the level in pen-carcinoma tissue. We found that GdCl3 suppressed the expression of CD206 in the M2 macrophage phenotype of stimulated RAW264.7 cells with an IC10 value of 0.07 mu g/mu l. In addition, GdCl3 also induced cell apoptosis in the RAW264.7 cells. Addition of GdCl3 into the culture medium of RAW264.7 cells markedly reduced the invasive ability of Hepal-6 cells compared to the control cells. Accordingly, GdCl3 treatment increased the expression of the epithelial-mesenchymal transition (EMT)-related protein E-cadherin while expression of N-cadherin, TWIST and Snail was reduced in IL-4-stimulated cells. Moreover, GdCl3 treatment inhibited HCC progression in DEN-induced HCC mice, possibly by downregulating CD206. Our findings indicate that CD206 is a potential biomarker for predicting HCC prognosis and that GdCl3 suppresses HCC progression by downregulating the expression of CD206 in TAMs.