title: Photodynamic therapy induced cell death of hormone insensitive prostate cancer PC-3 cells with autophagic characteristics.
abstract: BACKGROUND
  The introduction of photodynamic therapy (PDT) to the treatment of advanced prostate cancer can accomplish the eradication of local neoplasm and distant metastases with minimized damage to the adjacent structures. The evidence of PDT efficacy for androgen-refractory prostate cancer will be especially meaningful for the patients resistant to hormone therapy.
  
  
  METHODS
  Pheophorbide a (PhA) as a photosensitizer was employed to evaluate the photodynamic efficacy in androgen-insensitive PC-3 prostate cancer cells in culture by cell viability assay, reactive oxygen species (ROS) measurement and cell cycle test. Characteristics of apoptosis and autophagy were investigated via DNA fragmentation electrophoresis and immune-fluorescence staining, acidic vesicle determination and detection of LC3B in puncta form by fluorescence microscopy, Western blotting of autophagy-related (Atg) proteins and detailed phenotype shown by electron microscopy.
  
  
  RESULTS
  PhA exerted significant photo-cytotoxicity toward androgen-insensitive prostate cancer PC-3 cells in photosensitizer-dose and light-dose dependent manners. The photoactivation immediately initiated hyperproduction of ROS, the depolarization of mitochondrial membrane potential and the arrest of the cell cycle in the G0/G1 phase. Autophagy was revealed in PhA-PDT treated PC-3 cells by a significant high amount of acidic vesicular organelles with acridine orange staining, recruitment of LC3B on the membrane of autophagosomes by fluorescent microscopy, double membrane-bound vesicles suggesting autophagosomes by electron microscopy, significant increased Atg proteins such as beclin-1, Atg12-Atg5 conjugation, Atg7 and the conversion of LC3B-I to LC3B-II by Western blot analysis.
  
  
  CONCLUSIONS
  PhA-mediated PDT induced significant autophagy in hormone-refractory prostate cancer PC-3 cells.
authors.affiliation: School of Chinese Medicine, The Chinese University of Hong Kong, Hong Kong Special Administrative Region.
authors.forename: Dan Dan
authors.initials: DD
authors.lastname: Xu
authors.forename: Hon Ming
authors.initials: HM
authors.lastname: Lam
authors.forename: Robin
authors.initials: R
authors.lastname: Hoeven
authors.forename: Chong Bing
authors.initials: CB
authors.lastname: Xu
authors.forename: Albert Wing Nang
authors.initials: AW
authors.lastname: Leung
authors.forename: William Chi Shing
authors.initials: WC
authors.lastname: Cho
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000528:radiation effects; D001343:Autophagy / Q000187:drug effects* / Q000528:radiation effects; D002453:Cell Cycle / Q000187:drug effects / Q000528:radiation effects; D045744:Cell Line, Tumor; D002734:Chlorophyll / Q000031:analogs & derivatives* / Q000627:therapeutic use; D006801:Humans; D008297:Male; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D064129:Prostatic Neoplasms, Castration-Resistant / Q000188:drug therapy* / Q000473:pathology*; D016896:Treatment Outcome
chemical_list: D017319:Photosensitizing Agents; D002734:Chlorophyll; C032623:pheophorbide a
keywords: Autophagy; Pheophorbide a; Photodynamic therapy; Prostate cancer