title: Hypocrellin B enhances ultrasound-induced cell death of nasopharyngeal carcinoma cells.
abstract: Hypocrellin B, a natural pigment from a traditional Chinese herb, has been attracting extensive attention. The present study aims to investigate whether hypocrellin B can enhance cell death induced by ultrasound sonification on nasopharyngeal carcinoma cells in vitro. The sonodynamic action of hypocrellin B was investigated on nasopharyngeal carcinoma cell line CNE2 cells as tumor model cells. In the experiments, the hypocrellin B concentration was kept constant at 2.5 microM and the cells were subject to ultrasound exposure for 15 s at an intensity of 0.65 W/cm(2). Cytotoxicity was investigated 24 h after ultrasound sonification. Apoptosis was evaluated using flow cytometry with annexin V-FITC and propidium iodine staining and nuclear staining with Hoechst 33258. Cell ultrastructure morphology was observed using transmission electron microscopy (TEM). No significant dark cytotoxicity of hypocrellin B in the CNE2 cells was observed at the concentration of 2.5 microM. The cell death rate induced by ultrasound sonification was significantly higher in the presence of hypocrellin B than in the absence of hypocrellin B. Flow cytometry showed that ultrasound exposure in the presence of hypocrellin B significantly increased the early and late apoptotic rate, 18.64% and 22.57%, respectively, compared with the controls. Nuclear condensation was observed in the nuclear staining and swollen mitochondria and more vacuolar and broken cell membrane were found in TEM after the treatment of hypocrellin B and ultrasound. Our findings demonstrated that the presence of hypocrellin B significantly enhanced the cytotoxicity of ultrasound radiation in CNE2 cells, suggesting that hypocrellin B is a novel sonosensitizer and hypocrellin B-mediated sonodynamic therapy is a potential therapeutic modality in the management of malignant tumors.
authors.affiliation: Department of Photodynamic and Sonodynamic Therapy, The Second Affiliated Hospital, Chongqing Medical University, Chongqing, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Wang
authors.forename: Chuan-Shan
authors.initials: CS
authors.lastname: Xu
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Xinna
authors.initials: X
authors.lastname: Wang
authors.forename: Albert Wingnang
authors.initials: AW
authors.lastname: Leung
mesh_terms: D002277:Carcinoma / Q000628:therapy*; D016923:Cell Death / Q000187:drug effects*; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D006801:Humans; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D009303:Nasopharyngeal Neoplasms / Q000628:therapy*; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011809:Quinones / Q000737:chemistry / Q000494:pharmacology*; D014464:Ultrasonic Therapy
chemical_list: D017319:Photosensitizing Agents; D011809:Quinones; D010569:Perylene; C064522:hypocrellin B