Hepatoma-Derived Growth Factor Promotes Liver Carcinogenesis by Inducing Phosphatase and Tensin Homolog Inactivation

Abstract

Hepatoma-derived growth factor (HDGF) is located on chromosome 1q21-23, a locus frequently amplified in hepatocellular carcinoma (HCC), and has been proposed as an oncogenic factor by stimulating PI3K/Akt signaling. Phosphatase and tensin homolog (PTEN) acts as a tumor suppressor that antagonizes PI3K/Akt signaling, suggesting a possible regulatory effect of HDGF on PTEN. In this study, we aimed to investigate the regulatory role of HDGF on PTEN. The Cancer Genome Atlas cohort study was used to explore molecular significance and outcomes in liver cancer. Resected clinical specimens, consisting of paired tumor and adjacent nontumor tissue, were analyzed for expression of HDGF and PTEN in the liver cancer cohort. Liver tissue and primary hepatocytes derived from HDGF knockout mice were analyzed for PTEN status. The influence of HDGF on PTEN was investigated through in vitro and in vivo genetic manipulation studies. The Cancer Genome Atlas cohort study revealed an inverse correlation between HDGF and PTEN, with HDGF overexpression emerging as a dominant factor independent of PTEN levels and correlated with poor outcomes in patients with HCC. Paired clinical specimens revealed HDGF upregulation in tumor tissue is relevant to elevated alpha-fetoprotein, and poor survival and recurrent outcomes in the liver cancer cohort. HDGF knockout mice exhibited decreased liver C-tail--phosphorylated PTEN (p-PTEN) levels and increased PTEN expression. Furthermore, an in vitro study validated that overexpression of HDGF increased p-PTEN levels and tumor growth, whereas knockdown of HDGF yielded inverse results. Treatment with recombinant HDGF confirmed the stimulation of p-PTEN and accumulation of phosphatidylinositol 3,4,5-trisphosphate. Blockade of HDGF and casein kinase 2 signaling using anti-HDGF and a casein kinase 2 inhibitor validated the stimulation of p-PTEN. Our results reveal that HDGF is an oncogene frequently amplified and upregulated, leading to suppression of PTEN expression and activity, thereby contributing to malignant progression in liver cancer. HDGF upregulation in resected paired-HCC specimens may constitute a valuable prognostic biomarker for patients with HCC.