Sonodynamic Killing Of MPPA On Liver Cancer Cells

Background/Objective: Liver cancer is increasing worldwide and remains to be the main cause of death in the Asia and Africa, especially China. It was estimated that more than one-half of the global cases of primary liver cancer was Chinese. Recent therapeutic modalities for liver cancer, for example surgical therapy, radiotherapy and chemotherapy, are initially successful in the majority of cases. However, the mortality of patients with liver cancer is still high. Therefore, developing novel therapeutic strategies is mandatory. In view of increasing evidence that sonodynamic therapy is a potential therapeutic modality for combating malignant tumor. The study has investigated the sonodynamic action of MPPa in a mouse liver cancer cell line H22 cells. Our aims are to provide the evidence for MPPa-mediated sonodynamic therapy on liver cancer.Materials/Methods: The intracellular fluorescence of MPPa in the H22 cells was measured by flow cytometry (FCM). The cytotoxicity and mode of death induced by a novel developed photosensitizer MPPa were investigated in a mouse liver cancer cell line H22, in which the drug concentration was 2μmol/l and the frequency of ultrasound wave was 1.7 MHz and the ultrasound intensity of 0.97 W/cm2 was adopted. Sonodynamic cytotoxicity was investigated 24h after treatment, cell morphology was also observed by light microscopy at the same time. Furthermore, the temperature changes of solution were recorded as well. Apoptosis was determined using FCM with Annexin V-FITC staining, and nuclear staining with Hoechst 33258. Ultrastructure was observed using transmission electron microscopy. Mitochondrial membrane potential was evaluated using Rhodamine 123 assay. Finally, intracellular reaction oxygen species were monitored using the flow cytometric method with 2, 7-dichlorodihydrofluorecein diacetate (DCFH-DA) staining.Results: The intracellular fluorescence of MPPa in the H22 cells peaked at round 20h after sensitization. Ultrasound-activated MPPa mediates a time-dependent cytotoxicity in the H22 cells. And light microscopy confirmed the above findings. No significant temperature changes were found in the study time range. Nuclear staining showed that DNA condensation and fragmentation occurred after sonodynamic therapy, indicating the cell death was by the apoptotic mode. Apoptotic rate 6h after SDT with MPPa increased. Transmission electron microscopy showed the ultrastructure of H22 cells 6h after sonodynamic treatment, that apoptotic bodies and necrosis was displayed. Mitochondrial membrane potential collapsed 6h after being sensitized with 2μmol/l MPPa 20h and exposed to Ultrasound with 0.97W/cm2. Moreover, The fluorescent intensity of cells was measured using flow cytometry with DCFH-DA staining, showed that the spectral shift of the fluorescence curve to the right 3h after sonodynamic treatment was more significant than that after ultrasound radiation alone and MPPa treatment alone. This indicated that sonodynamic action of MPPa enhanced the intracellular reaction oxygen species (ROS) level.Conclusion: Sonodynamic action of MPPa could significantly kill the liver cancer cells. Our results indicated that MPPa was a novel sonosensitizer and MPPa-mediated SDT might be a potential therapeutic modality in the management of malignancies.