p55PIK regulates alpha-fetoprotein expression through the NF-κB signaling pathway

Alpha-fetoprotein (AFP) is regarded as a diagnostic and prognostic biomarker and a potential therapeutic target for hepatocellular carcinoma (HCC). However, the regulation of AFP expression in HCC remains poorly understood. This study aimed to investigate the mechanism by which AFP expression is regulated by p55PIK, an isoform of PI3K.

Human HCC cell lines (HepG2 and Huh-7) were treated with p55PIK specific competitive inhibitor or shRNA, or p55PIK overexpression vector, in the absence or presence of NF-κB inhibitor PDTC. AFP expression was detected by quantitative real-time PCR and Western blotting. NF-κB responsive elements in AFP enhancer region were characterized by luciferase reporter assay.

p55PIK significantly stimulated the expression of AFP by activating NF-κB signaling pathway in HCC cells. Furthermore, two NF-κB binding sites in AFP enhancer region were identified to be primarily responsible for p55PIK mediated upregulation of AFP expression.

p55PIK/NF-κB signaling plays an important role in the upregulation of AFP expression in HCC.