Hepatic stellate cells secretes type I collagen to trigger epithelial mesenchymal transition of hepatoma cells.

Liver fibrosis is a risk factor for hepatoma. Activated hepatic stellate cells (HSCs) play a critical role in progression of hepatoma. Resected hepatoma patients with high α-SMA+HSCs infiltration had worse survival, OR: 2.2 and p=0.0434. We hypothesized that HSCs could increase the epithelial-mesenchymal transition (EMT) ability of hepatoma cells. In murine model of liver fibrosis with injection of ML1 mice HCC cell line, E-cadherin was lost at the margin of tumor nodule around α-SMA+HSC sites. In subcutaneous tumor model, HSCs could increase the metastatic nodules in the lung, and the expression of E-cadherin was decreased and the Slug was induced. To elucidate the effect of HSCs on hepatoma cells, HSC-T6 was co-cultured with ML1 and the condition medium of HSC-T6 can trigger ML1 cell morphological change, down-expression of E-cadherin, induction of Slug expression, and cell migration. Proteomic analysis of the condition medium showed that collagen I was the target molecule. Collagen type I alone also induced EMT of ML1 cells. Knockdown of collagen type I in HSC-T6 could decrease its induction of EMT on ML1 cells. In conclusion, HSC can secrete collagen type I to trigger hepatoma cells to undergo EMT for metastasis.