Selective and Non-Selective Pharmacological Activation of Hypoxia-Inducible Factor Differentially Modulate Cancer Progression of Hepatocellular Carcinoma Cell Line HepG2

Cellular adaptation to hypoxia is mediated by hypoxia-inducible factor (HIF), a transcription factor primarily regulated by prolyl hydroxylases (PHDs) in an oxygen-dependent manner. In hepatocellular carcinoma (HCC), HIF is overexpressed but its role in driving tumour progression remains unclear. This study investigated the effects of pharmacological HIF pathway activation on proliferation, epithelial-mesenchymal transition (EMT) and oxidative stress in the HepG2 human HCC cell line. Three PHD inhibitors were used: a non-selective iron-chelator deferoxamine (DFO), a pan-inhibitor of 2-oxoglutarate (2-OG)-oxygenases dimethyloxalylglycine (DMOG) and a selective inhibitor of the PHDs IOX2. DFO reduced proliferation in a concentration- and time-dependent manner, while DMOG and IOX2 induced proliferation at lower concentrations. EMT induction by DFO was evidenced by reduced epithelial marker E-cadherin and increased mesenchymal marker alpha-smooth muscle actin (α-SMA) levels. In contrast, IOX2 upregulated E-cadherin and downregulated α-SMA levels in a concentration-dependent manner, correlating with HIF-α activation, suggesting reduced EMT. Reactive oxygen species (ROS) levels remained unchanged with IOX2 but were reduced by DMOG. These findings suggest that selective HIF activation using IOX2 promotes proliferation while reduces EMT without affecting ROS levels in HepG2, whereas non-selective HIF activation by DFO and DMOG produce differential effects to that of IOX2, likely via off-target effects.