Osthole delays hepatocarcinogenesis in mice by suppressing AKT/FASN axis and ERK phosphorylation

Abstract

Hepatocellular carcinoma (HCC) is one of the most common fatal malignancies worldwide. Inhibition of the lipogenic enzymes involved in hepatic de novo lipogenesis can both effectively restrain proliferation of HCC cells in vitro and reduce the risk of hepatocarcinogenesis in vivo. Although a natural coumarin derivative osthole shows efficacy in suppressing cell proliferation and inducing apoptosis in cultured hepatoma cells and HCC xenograft tumors, the molecular mechanism by which osthole delays hepatocellular malignant transformation during lipogenesis-driven hepatocarcinogenesis remains unknown. Here, we evaluate the efficacy of osthole in a rapid HCC mouse model featuring excessive levels of hepatic steatosis established via hydrodynamic transfection of activated forms of AKT and c-Met proto-oncogenes. Moreover, human hepatoma cell lines were employed for in vitro assessment. Hematoxylin and eosin staining, immunoblotting and immunohistochemistry were applied for mechanistic investigations. The results revealed that if osthole was administered in the early stage of AKT/c-Met-driven HCC, it led to disease stabilization. Moreover, osthole alleviated hepatic steatosis in the AKT/c-Met mice. Further evidence at the molecular level suggested that osthole reduced the expression of phosphor-extracellular signal-regulated kinase 1/2 (ERK1/2), proliferating cell nuclear antigen (PCNA) and Ki67 in livers of the AKT/c-Met mice. Mechanically, osthole efficiently repressed the phospho-AKT (Thr308) / ribosomal protein S6 (RPS6) / fatty acid synthase (FASN) signaling both in mice and in vitro. Altogether, this study suggests that osthole exerts its antilipogenic and antiproliferative efficacy by suppressing the AKT/FASN axis and ERK phosphorylation, which contributes to its capacity to delay hepatocarcinogenesis.