title: Protoporphyrin IX-mediated sonodynamic action induces apoptosis of K562 cells.
abstract: OBJECTIVE
  The present study aims to investigate apoptosis of human leukemia K562 cells induced by protoporphyrin IX (PpIX)-mediated sonodynamic therapy (PpIX-SDT).
  
  
  METHODS
  The uptakes of intracellular PpIX in K562 cells were detected by flow cytometry. The sub-cellular localization of PpIX was imaged by confocal microscope. The cytotoxic effect of PpIX-SDT was assessed by MTT (3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenylter-trazolium bromide tetrazolium) assay. Apoptosis was evaluated by chromatin condensation with DAPI (4'-6-diamidino-2-phenylindole) staining, decrease of mitochondria membrane potential (MMP), re-distribution of Bax, and the expression changes of the key apoptosis-associated protein (Caspase-3 and polypeptide poly (ADP-robose) polymerase). The possible mechanism of SDT-induced apoptosis was investigated by detecting by intracellular ROS (reactive oxygen species) generation and effect of ROS scavenger-NAC (N-acetylcysteine) on SDT induced apoptosis.
  
  
  RESULTS
  The intracellular PpIX increased quickly within 2 h after PpIX administration and PpIX mainly localized in the mitochondria. Compared with PpIX alone and ultrasound alone groups, the synergistic cytotoxicity of PpIX plus ultrasound was significantly boosted. In addition, the ultrasound induced some extent of chromatin condensation and MMP loss was greatly enhanced by the presence of 2 μg/ml PpIX, where PpIX alone treatment showed no or only slight effect. Time-dependent Bax translocation, caspase-3 activation and PARP cleavage were detected in SDT treatment groups. Besides, intracellular ROS production was significantly enhanced after SDT, and the general ROS scavenger NAC could obviously alleviate the SDT-caused cell viability loss, MMP loss, Bax redistribution and nuclear changes.
  
  
  CONCLUSIONS
  These results indicated that PpIX-mediated sonodynamic action could induce apoptosis on K562 cells, and the intracellular ROS was involved in the PpIX-SDT induced apoptosis.
authors: Key Laboratory of Medicinal Resources and Natural Pharmaceutical Chemistry, Ministry of Education, National Engineering Laboratory for Resource Developing of Endangered Chinese Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi'an, 710062 Shaanxi, China.
authors: Xiaomin
authors: X
authors: Su
authors: Yixiang
authors: Y
authors: Li
authors: Pan
authors: P
authors: Wang
authors: Xiaobing
authors: X
authors: Wang
authors: Quanhong
authors: Q
authors: Liu
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects; D004586:Electrophoresis / Q000379:methods*; D006801:Humans; D020014:K562 Cells; D011524:Protoporphyrins / Q000008:administration & dosage*; D011838:Radiation-Sensitizing Agents / Q000008:administration & dosage; D013010:Sonication / Q000379:methods*; D014464:Ultrasonic Therapy / Q000379:methods*
chemical_list: D011524:Protoporphyrins; D011838:Radiation-Sensitizing Agents; C028025:protoporphyrin IX
keywords: Apoptosis; Human leukemia K562 cells; Protoporphyrin IX; ROS; Sonodynamic therapy