Berberine, a natural alkaloid sensitizes human hepatocarcinoma to ionizing radiation by blocking autophagy and cell cycle arrest resulting in senescence

Objective To study the radiosensitizing potential of Berberine and the underlying mechanism in human hepatocarcinoma (HepG2) cells. Methods HepG2 cells were challenged with X-rays in combination with Berberine treatment and severalin vitroassays were performed. Alteration in cell viability was determined by MTT assay. Changes in intracellular ROS levels, mitochondrial membrane potential/mass, intracellular acidic vesicular organelles as well as cell cycle arrest and apoptotic cell death were analysed by flow cytometry. Induction of autophagy was assessed by staining the cells with Monodansylcadaverine/Lysotracker red dyes and immunoblotting for LC3I/II and p62 proteins. Phase-contrast/fluorescence microscopy was employed to study mitotic catastrophe and senescence. Cellular senescence was confirmed by immunoblotting for p21 levels and ELISA for Interleukin-6. Key findings X-rays + Berberine had a synergistic effect in reducing cell proliferation accompanied by a robust G2/M arrest. Berberine-mediated radiosensitization was associated with elevated levels of LC3II and p62 suggesting blocked autophagy that was followed by mitotic catastrophe and senescence. Treatment of cells with X-rays + Berberine resulted in increased oxidative stress, hyperpolarized mitochondria with increased mitochondrial mass and reduced ATP levels. Conclusions The study expands the understanding of the pharmacological properties of Berberine and its applicability as a radiosensitizer towards treating liver cancer.