title: Apoptosis of ovarian cancer cells induced by methylene blue-mediated sonodynamic action.
abstract: OBJECTIVE
  The present study aims to investigate apoptosis of ovarian cancer cells induced by methylene blue (MB)-mediated sonodynamic therapy (SDT).
  
  
  METHODS
  The MB concentration was kept constant at 100μM and ovarian cancer HO-8910 cells were exposed to ultrasound therapy for 5s with an intensity of 0.46W/cm(2). The cytotoxicity was investigated 24h after MB-mediated sonodynamic action. Apoptosis was analyzed using a flow cytometer with Annexin V-FITC and propidium iodine (PI) staining as well as fluorescence microscopy with Hoechst 33258 staining. Intracellular reactive oxygen species (ROS) level was measured by flow cytometer with 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) staining.
  
  
  RESULTS
  The cytotoxicity of MB-mediated SDT on HO-8910 cells after MB-mediated SDT was significantly higher than those of other treatments including ultrasound alone, MB alone and sham treatment. Flow cytometric analysis showed a significant increase in the early and late apoptotic cell populations by MB-mediated SDT of HO-8910 cells. Nuclear condensation and increased ROS levels were also found in HO-8910 cells treated by MB-mediated SDT.
  
  
  CONCLUSIONS
  Our findings demonstrated that MB-mediated sonodynamic action significantly induced apoptosis of HO-8910 cells and an increase in intracellular ROS level. This indicates that apoptosis is an important mechanism of cell death induced by MB-mediated SDT. Thus, MB-mediated SDT might be a potential therapeutic strategy for combating ovarian cancer.
authors.affiliation: Department of Photodynamic and Sondynamic Therapy, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, China.
authors.forename: Junyan
authors.initials: J
authors.lastname: Xiang
authors.forename: Xinshu
authors.initials: X
authors.lastname: Xia
authors.forename: Yuan
authors.initials: Y
authors.lastname: Jiang
authors.forename: Albert Wingnang
authors.initials: AW
authors.lastname: Leung
authors.forename: Xinna
authors.initials: X
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Heping
authors.initials: H
authors.lastname: Yu
authors.forename: Dingqun
authors.initials: D
authors.lastname: Bai
authors.forename: Chuanshan
authors.initials: C
authors.lastname: Xu
mesh_terms: D000704:Analysis of Variance; D017209:Apoptosis; D005260:Female; D005434:Flow Cytometry; D005452:Fluoresceins; D006801:Humans; D008751:Methylene Blue / Q000494:pharmacology*; D008856:Microscopy, Fluorescence; D010051:Ovarian Neoplasms / Q000628:therapy*; D017382:Reactive Oxygen Species; D014407:Tumor Cells, Cultured; D014464:Ultrasonic Therapy / Q000379:methods*
chemical_list: D005452:Fluoresceins; D017382:Reactive Oxygen Species; C029569:diacetyldichlorofluorescein; D008751:Methylene Blue