Isoliquiritigenin inhibits cell proliferation by a heme oxygenase-dependent pathway in rat hepatic stellate cells.

We evaluated whether the antiproliferative effects of isoliquiritigenin (ISL) on rat hepatic stellate cells (HSCs) are related to the induction of heme oxygenase 1 (HO-1) expression. ISL significantly inhibited serum- or growth factor-induced HSC proliferation. The inhibition of platelet-derived growth factor (PDGF)-induced proliferation by ISL was associated with the mitogen-activated protein kinase and phosphatidylinositol 3-kinase-Akt-p70 (S6K) pathways. ISL induced the expression of HO-1 in HSCs. Using the chemical inhibitor tin protoporphyrin, we also found that the inhibitory action of ISL on PDGF-induced proliferation is mediated by HO-1. These data suggest that HO-1 expression is responsible for the antiproliferative effect of ISL on HSCs.