title: Apoptosis Induced by Microbubble-Assisted Acoustic Cavitation in K562 Cells: The Predominant Role of the Cyclosporin A-Dependent Mitochondrial Permeability Transition Pore.
abstract: Acoustic cavitation of microbubbles has been described as inducing tumor cell apoptosis that is partly associated with mitochondrial dysfunction; however, the exact mechanisms have not been fully characterized. Here, low-intensity pulsed ultrasound (1 MHz, 0.3-MPa peak negative pressure, 10% duty cycle and 1-kHz pulse repetition frequency) was applied to K562 chronic myelogenous leukemia cells for 1 min with 10% (v/v) SonoVue microbubbles. After ultrasound exposure, the apoptotic index was determined by flow cytometry with annexin V-fluorescein isothiocyanate/propidium iodide. In addition, mitochondrial membrane potential (ΔΨm) was determined with the JC-1 assay. Translocation of apoptosis-associated protein cytochrome c was evaluated by Western blotting. We found that microbubble-assisted acoustic cavitation can increase the cellular apoptotic index, mitochondrial depolarization and cytochrome c release in K562 cells, compared with ultrasound treatment alone. Furthermore, mitochondrial dysfunction and apoptosis were significantly inhibited by cyclosporin A, a classic inhibitor of the mitochondrial permeability transition pore; however, the inhibitor of Bax protein, Bax-inhibiting peptide, could not suppress these effects. Our results suggest that mitochondrial permeability transition pore opening is involved in mitochondrial dysfunction after exposure to microbubble-assisted acoustic cavitation. Moreover, the release of cytochrome c from the mitochondria is dependent on cyclosporin A-sensitive mitochondrial permeability transition pore opening, but not formation of the Bax-voltage dependent anion channel complex or Bax oligomeric pores. These data provide more insight into the mechanisms underlying mitochondrial dysfunction induced by acoustic cavitation and can be used as a basis for therapy.
authors.affiliation: Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi' an Jiaotong University, Xi' an, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi' an Jiaotong University, Xi' an, China. Electronic address: fengyi@mail.xjtu.edu.cn.
authors.forename: Yi
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi' an Jiaotong University, Xi' an, China.
authors.forename: Aiwei
authors.initials: A
authors.lastname: Shi
authors.affiliation: Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi' an Jiaotong University, Xi' an, China.
authors.forename: Yujin
authors.initials: Y
authors.lastname: Zong
authors.affiliation: Key Laboratory of Biomedical Information Engineering of Ministry of Education, Department of Biomedical Engineering, School of Life Science and Technology, Xi' an Jiaotong University, Xi' an, China. Electronic address: mxwan@mail.xjtu.edu.cn.
authors.forename: Mingxi
authors.initials: M
authors.lastname: Wan
mesh_terms: D017209:Apoptosis / Q000528:radiation effects*; D016572:Cyclosporine / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D020014:K562 Cells; D045423:Microbubbles / Q000627:therapeutic use*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism*; D000083162:Mitochondrial Permeability Transition Pore; D009374:Neoplasms, Experimental / Q000378:metabolism* / Q000473:pathology / Q000628:therapy; D011829:Radiation Dosage; D013010:Sonication / Q000379:methods; D013016:Sound; D014464:Ultrasonic Therapy / Q000379:methods*
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D000083162:Mitochondrial Permeability Transition Pore; D016572:Cyclosporine
keywords: Acoustic cavitation; Cyclosporin A; Cytochrome c; Microbubble; Mitochondrial permeability transition pore