Cancer-associated fibroblasts promote stem cell-like properties of hepatocellular carcinoma cells through IL-6/STAT3/Notch signaling

In this study, we investigated the role of cancer-associated fibroblasts (CAFs) in hepatocellular carcinoma (HCC) progression. We showed that CAFs secrete high levels of IL-6, which promoted stem cell-like properties in HCC cells by activating Notch signaling through STAT3 Tyr705 phosphorylation. These effects were abolished by Notch1 shRNA knockdown in HCC cells or treatment with an IL-6 neutralizing antibody or the p-STAT3 (Tyr705) inhibitor cryptotanshinone. Xenografted liver tumors were larger in nude mice injected with HCC cells and CAFs than in those receiving HCC cells alone. Moreover, immunohistochemical analysis of liver tissue specimens from 88 HCC patients revealed that high nuclear Notch intracellular domain (nNICD) levels in HCC cells correlated with poor prognosis in patients. These findings suggest that IL-6 secreted by CAFs promotes stem cell-like properties in HCC cells by enhancing STAT3/Notch signaling.