Mechanically stimulated hepatic stellate cells release WNT5A that triggers apoptosis in HCC cell lines

WNT5A is a ligand of non-canonical WNT signaling and highly expressed in liver fibrosis and cirrhosis leading to hepatocellular carcinoma (HCC). Activated hepatic stellate cells (HSC) and myofibroblasts are major sources of WNT5A in the liver. Here we report that isolated rat HSC exposed to fluid shear stress, stretching, or stiff substrate release significantly more WNT5A than the respective controls. These mechanical stimuli mimic altered blood flow and tissue stiffness of diseased liver. Among genes that show increased expression in HSC after applying mechanical forces, the mechanically gated ion channel PIEZO1 was identified. CRISPR/Cas9-mediated knockout of Piezo1 in HSC lowered WNT5A release in response to mechanical stimuli, indicating that PIEZO1 is a mechanosensor in HSC. Interestingly, α-smooth muscle actin-positive myofibroblasts that surround HCC co-expressed PIEZO1. Therefore, we tested if recombinant rat WNT5A could affect the proliferation of the rat HCC cell lines H4IIE and N1S1. Treatment of the tumor cells with 1 µg/ml WNT5A significantly reduced the cell proliferation of both HCC cell lines within 4 hours as investigated by bromodeoxyuridine assays. TUNNEL assays indicated that WNT5A triggered apoptosis in the adherent growing H4IIE line. These findings are in line with earlier studies that reported apoptosis in WNT5A-treated tumor cells from other organs. However, proliferation of tumor cells in response to WNT5A treatment has also been described. Further studies are needed to clarify whether transcript variants of WNT5A or an alternative signaling modify the outcome of non-canonical WNT pathways and may enable an escape of tumor cells from apoptosis.

Publication History

Article published online:
26 January 2022