title: Ca(2+)-dependent and caspase-3-independent apoptosis caused by damage in Golgi apparatus due to 2,4,5,7-tetrabromorhodamine 123 bromide-induced photodynamic effects.
abstract: To clarify the role of the Golgi apparatus in photodynamic therapy-induced apoptosis, its signaling pathway was studied after photodynamic treatment of human cervix carcinoma cell line HeLa, in which a photosensitizer, 2,4,5,7-tetrabromorhodamine 123 bromide (TBR), was incorporated into the Golgi apparatus. Laser scanning microscopic analysis of TBR-loaded HeLa cells confirmed that TBR was exclusively located in the Golgi apparatus. HeLa cells incubated with TBR for 1 h were then exposed to visible light using an Xe lamp. Light of wavelength below 670 nm was eliminated with a filter. Morphological observation of nuclei stained with Hoechst 33342 revealed that apoptosis of cells was induced by exposure to light. Electron spin resonance spectrometry showed that light-exposed TBR produced both singlet oxygen (1O2) and superoxide anion (O2-). Apoptosis induction by TBR was inhibited by pyrrolidine dithiocarbamate, an O2- scavenger, but not by NaN3, a quencher of 1O2. Furthermore, TBR-induced apoptosis was inhibited by aurintricarboxylic acid and ZnCl2, which are known as inhibitors of deoxyribonuclease (DNase) gamma, and (acetoxymethyl)-1,2-bis(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid, a chelator of Ca2+, but not by acetyl Asp-Glu-Val-Asp-aldehyde, an inhibitor of caspase-3. These results suggested that O2- was responsible for TBR-induced apoptosis, and Ca(2+)-dependent and caspase-3-independent nuclease such as DNase gamma played an important role in apoptotic signaling triggered by Golgi dysfunction.
authors.affiliation: Laboratory of Radiation Biology, Department of Environmental Veterinary Science, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Japan.
authors.forename: Maiko
authors.initials: M
authors.lastname: Ogata
authors.forename: Osamu
authors.initials: O
authors.lastname: Inanami
authors.forename: Mihoko
authors.initials: M
authors.lastname: Nakajima
authors.forename: Takayuki
authors.initials: T
authors.lastname: Nakajima
authors.forename: Wakako
authors.initials: W
authors.lastname: Hiraoka
authors.forename: Mikinori
authors.initials: M
authors.lastname: Kuwabara
mesh_terms: D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D002118:Calcium / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000502:physiology*; D004578:Electron Spin Resonance Spectroscopy; D006056:Golgi Apparatus / Q000187:drug effects*; D006367:HeLa Cells; D006801:Humans; D010778:Photochemotherapy; D012235:Rhodamines / Q000009:adverse effects / Q000494:pharmacology*
chemical_list: D012235:Rhodamines; C060140:tetrabromorhodamine 123; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D002118:Calcium