Apoptosis of THP-1 Macrophages Induced by Pseudohypericin-Mediated Sonodynamic Therapy Through the Mitochondria-Caspase Pathway

Background/Aims: Pseudohypericin (P-HY) and its congener hypericin are the major hydroxylated phenanthroperylenediones present in Hypericum species. Our previous study indicated that hypericin was able to function as a sonosensitizer. The potential use of P-HY as a sonosensitizer for sonodynamic therapy (SDT) requires further exploration. Thus, this study aimed to investigate the effects of P-HY-SDT on THP-1 macrophages. Methods: THP-1 macrophages were incubated with P-HY, and cell viability was measured using a CCK-8 assay. Fluorescence microscopy assessed the intracellular reactive oxygen species (ROS), mitochondrial membrane potential (∆Ψm) and mitochondrial permeability transition pore (mPTP) opening. Apoptotic and necrotic cell levels were measured by the flow cytometry analysis. Western blots were employed to assay BAX, Cytochrome C expression and apoptosis-related proteins. Results: P-HY-SDT induced THP-1 macrophage apoptosis. The levels of ROS were significantly increased in the SDT group, resulting in both mPTP opening and ∆Ψm loss, which led to apoptosis. In addition, the translocation of BAX, release of Cytochrome C and the upregulated expression of apoptosis-related proteins after P-HY-SDT were observed, all of which were reversed by N-acetyl cysteine (NAC). Conclusion: P-HY-SDT induced THP-1 macrophage apoptosis through the mitochondria-caspase pathway via ROS generation, the translocation of BAX and the release of Cytochrome C to regulate the mPTP opening.