title: Apoptosis induced by the sonomechanical effects of low intensity pulsed ultrasound in a human leukemia cell line.
abstract: To obtain an optimal condition for ultrasound (US)-induced apoptosis that could be useful for cancer therapy, we applied low intensity pulsed US to sonicate U937 cells in vitro. Cells were then incubated at different time intervals before measuring apoptosis. The apoptosis was assessed by DNA fragmentation and phosphatidylserine externalization. The pattern of the decrease in mitochondrial membrane potential was determined by flow cytometry. Optimal apoptosis (70.0+/-13.8%) with minimal lysis was attained with 1 MHz ultrasound 0.3 W/cm2, 10% duty factor at 100 Hz for 1 min) at 12 h after sonication. Lack of US-induced free radical detection and absence of Heme oxygenase-1, an intracellular oxidative stress marker, up-regulation in cells, suggest that sonomechanical, not sonochemical, effects are the main mechanism involved.
authors.affiliation: Department of Radiological Sciences, Faculty of Medicine, Toyama Medical and Pharmaceutical University, 2630 Sagitani, Toyama 930-0194, Japan.
authors.forename: Loreto B
authors.initials: LB
authors.lastname: Feril
authors.forename: Takashi
authors.initials: T
authors.lastname: Kondo
authors.forename: Zheng-Guo
authors.initials: ZG
authors.lastname: Cui
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Tabuchi
authors.forename: Qing-Li
authors.initials: QL
authors.lastname: Zhao
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Ando
authors.forename: Takuro
authors.initials: T
authors.lastname: Misaki
authors.forename: Hideki
authors.initials: H
authors.lastname: Yoshikawa
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Umemura
mesh_terms: D017209:Apoptosis; D004578:Electron Spin Resonance Spectroscopy; D005434:Flow Cytometry; D005609:Free Radicals / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000378:metabolism; D051547:Heme Oxygenase-1; D006801:Humans; D007938:Leukemia / Q000378:metabolism* / Q000473:pathology; D008564:Membrane Potentials; D008565:Membrane Proteins; D008928:Mitochondria / Q000378:metabolism*; D018384:Oxidative Stress; D010718:Phosphatidylserines / Q000378:metabolism; D011674:Pulse; D013010:Sonication; D020298:U937 Cells
chemical_list: D005609:Free Radicals; D008565:Membrane Proteins; D010718:Phosphatidylserines; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1