Effects of CoCl2-Induced Hypoxia on HepG2 Cells: Increased VEGF and GLUT1 Gene Expression and Enhanced Doxorubicin Resistance

Abstract

This study explored the effects of cobalt chloride (CoCl₂), a hypoxia-mimicking agent, on HepG2 cells, with a focus on cell survival, gene expression, chemotherapy sensitivity, and drug efflux capacity. HepG2 cells were treated with various concentrations of CoCl₂ (50, 100, 150, 200, and 250 µM) and observed over different time periods (12, 24, and 48 hours). The results indicated that lower concentrations (50 and 100 µM) did not significantly impact cell viability, whereas higher concentrations (150, 200, and 250 µM) led to notable cytotoxicity, demonstrating a concentration-dependent effect. CoCl₂ treatment significantly increased the expression of vascular endothelial growth factor (VEGF) and glucose transporter 1 (GLUT1) at 72 and 96 hours, despite stable levels of hypoxia-inducible factor 1-alpha (HIF-1α). These findings suggest an increase in angiogenesis and metabolic adaptation. Additionally, CoCl₂-treated cells exhibited reduced sensitivity to the chemical drug doxorubicin, with increased IC50 values, indicating increased drug resistance. Furthermore, CoCl₂ treatment doubled the subpopulation of cells capable of effluxing rhodamine 123, suggesting increased drug efflux capacity. These findings underscore the effectiveness of CoCl₂ in mimicking hypoxia and its utility in studying hypoxia-related cellular responses and drug resistance in liver cancer cells. However, the results emphasize the necessity of carefully considering the CoCl₂ concentration and exposure time to ensure accurate and relevant experimental outcomes.