Hepatocarcinoma cells stimulate the growth, migration and expression of pro-angiogenic genes in human hepatic stellate cells

Abstract

Activated hepatic stellate cells (HSC) and other fibrogenic cell types are frequently found around hepatocellular carcinoma. It is unknown whether hepatocarcinoma cells regulate the biological functions of HSC. This study aimed to investigate the paracrine effects of hepatocarcinoma cells on human HSC using a co-culture system. Huh7 or HepG2 cells, human hepatocarcinoma cell lines, were co-cultured with primary human HSC. Intracellular calcium mobilization, proliferation, migration, expression of pro-angiogenic and fibrogenic genes, smooth muscle alpha-actin (alpha-SMA) protein expression, inflammatory properties (nuclear factor kappa B activation and interleukin 8 secretion) and intracellular signalling pathways (AKT and ERK) were analysed in HSC. Culture of HSC with Huh7 cells for 24 h stimulated HSC proliferation, migration and expression of pro-angiogenic genes. The migration effect was corroborated with HepG2 cells. The effects of Huh7 cells on cell proliferation and migration were mediated mainly by PI3K/AKT activation. Moreover, Huh7 cells reduced the expression of genes involved in fibrogenesis, while they did not modify the inflammatory properties of HSC. The expression of alpha-SMA was induced by Huh7 cells. Because hepatitis C virus (HCV) infection is a major cause of hepatocarcinoma, we next investigated whether these effects are regulated by the expression of HCV in hepatocarcinoma cells. Expression of a subgenomic replicon expressing HCV nonstructural proteins (NS3-NS5) in Huh7 cells did not affect paracrine actions in HSC (cell proliferation and migration). These results suggested that there is a cross-talk between hepatocarcinoma cells and HSC. Activated HSC may be stimulated by cancer cells to accumulate and express angiogenic genes.