IL-6, a risk factor for hepatocellular carcinoma: FLLL32 inhibits IL-6-induced STAT3 phosphorylation in human hepatocellular cancer cells.

Hepatocellular carcinoma (HCC) is one of the most common human cancers and the patients' five-year survival rate is very low. Growing evidence indicates that interleukin-6 (IL-6) is a risk factor for HCC. High serum IL-6 may promote HCC development in hepatitis B patients. Therefore, IL-6 could be considered a HCC biomarker and blockade of IL-6 pathway may be a promising therapeutic alternative for HCC. STAT3 is major pathway to mediate signal from IL-6 to the nucleus, where different genes associated with proliferation and apoptosis are regulated. We previous reported that IL-6 induces cell survival upon drug treatment in HCC cells and inhibition of IL-6/STAT3 pathway using anti-IL-6 antibody or STAT3 small-molecule inhibitor LLL12 reduces this effect. Here we summarized the recent studies of IL-6 in HCC and showed another STAT3 small-molecule inhibitor FLLL32 also blocked IL-6-induced STAT3 activation in HCC cells. FLLL32 is a novel curcumin analogue, which has been described to suppress the constitutive activation of STAT3 in pancreatic and breast cancer cells in vitro and vivo. We demonstrated that FLLL32 blocked IL-6-induced STAT3 phosphorylation and nuclear translocation.