Hesperetin Induces Apoptosis in Human Glioblastoma Cells via p38 MAPK Activation

Glioblastoma (GBM) is the most common and aggressive form of malignant brain tumor, with poor prognosis and a lack of effective treatment. Hesperetin, a natural product found in citrus fruits, displayed bioactivities including antioxidant, anti-inflammatory, and anticancer, while its effects on GBM cells were largely unknown. Here, we explored the anticancer effect of hesperetin on human GBM cells in vitro, as well as the underlying signaling mechanisms. By CCK-8 assay and live/dead assay, hesperetin presented significant inhibitory effect on human GBM U-251 and U-87 cell viability. By DAPI staining and Annexin V-FITC/PI assay, apoptotic death was proved to contribute to the cell viability reduction, and it was verified by the increased Bax/Bcl-2 ratio in western blotting results. Furthermore, by cell cycle analysis and western blotting for cyclin B1, CDK1, and p21, hesperetin was found to induce cell-cycle arrest at G2/M phase. For signaling mechanism, the western blotting results showed elevated p38 MAPK activation, and the reduced Bcl-2 and enhanced Bax upon hesperetin treatment were partly reversed by p38 MAPK inhibitor SB203580. In summary, we have discovered hesperetin as a natural product candidate for the treatment of GBM, and that it could induce GBM cell apoptosis via p38 MAPK activation.