title: 9-Hydroxypheophorbide alpha-induced apoptotic death of MCF-7 breast cancer cells is mediated by c-Jun N-terminal kinase activation.
abstract: Recently, we synthesized 9-hydroxypheophorbide alpha (9-HPbD), a new chlorophyll-derived photosensitizer. The photo-treatment of MCF-7 human breast cancer cells with 20 kJ/m2 of red light after 5 microM 9-HPbD pretreatment induced cell death, showed typical apoptotic features, i.e., chromatin condensation, phosphatidyl serine externalization, membrane blebbing, and apoptotic bodies with an intact plasma membrane structure. To elucidate the mechanism of 9-HPbD-induced apoptosis, various mediators of the apoptosis were investigated. Release of cytochrome c from mitochondria into the cytosol was distinct 9 h after irradiation, while the levels of most apoptosis-related molecules such as Fas, FasL, Bcl-2, Bax and p53 were unchanged. Furthermore, caspase-9 activated by released cytochrome c was not significantly activated after 9-HPbD-photosensitization. On the other hand, stress-activated protein kinases such as p38 and c-Jun N-terminal kinase (JNK) were activated 1 h after irradiation. Blocking of JNK signaling by transfecting with the dominant negative from of the JNK gene significantly reduced 9-HPbD-induced cell death. Our data show that photosensitization with the new photosensitizer 9-HPbD could induce the apoptotic death of MCF-7 breast cancer cell and that this death is mediated by stress-activated signal through JNK.
authors.affiliation: Laboratory of Endocrinology, Institute for Medical Sciences, Ajou University School of Medicine, Wonchon-dong san 5, Paldal-Gu, Suwon, Kyunggi-do 442-749, Republic of Korea.
authors.forename: Sung-E
authors.initials: SE
authors.lastname: Choi
authors.forename: Seonghyang
authors.initials: S
authors.lastname: Sohn
authors.forename: Jeong-Woo
authors.initials: JW
authors.lastname: Cho
authors.forename: Eun-A
authors.initials: EA
authors.lastname: Shin
authors.forename: Pill-Soon
authors.initials: PS
authors.lastname: Song
authors.forename: Yup
authors.initials: Y
authors.lastname: Kang
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002734:Chlorophyll / Q000031:analogs & derivatives / Q000494:pharmacology*; D004789:Enzyme Activation; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D008854:Microscopy, Electron; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: C491791:9-hydroxypheophorbide alpha; D002734:Chlorophyll; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases