Induction of Caspase-dependent Apoptosis by Apigenin by Inhibiting STAT3 Signaling in HER2-overexpressing MDA-MB-453 Breast Cancer Cells

Background: This study aimed to examine the effect of apigenin on proliferation and apoptosis in HER2-overexpressing MDA-MB-453 breast cancer cells. Materials and Methods: The antiproliferative effects of apigenin were examined by proliferation and MTT assays. The effect of apigenin on apoptotic molecules was determined by western blotting. RT-PCR was performed to measure mRNA levels of HIF-1 alpha and VEGF. ELISA assay was performed to measure intracellular VEGF levels. Immunocytochemistry was performed to evaluate nuclear STAT3 level. Results: Apigenin inhibited the proliferation of MDA-MB-453 cells. Apigenin up-regulated the levels of cleaved caspase-8 and caspase-3, and induced the cleavage of PARP. Apigenin induced extrinsic apoptosis and blocked the activation (phosphorylation) of JAK2 and STAT3. Apigenin inhibited CoCl2-induced VEGF secretion and decreased the nuclear staining of STAT3. Conclusion: Apigenin exerts its antiproliferative activity by inhibiting STAT3 signaling. Apigenin could serve as a useful compound to prevent or treat HER2-overexpressing breast cancer.