title: Anti-apoptotic effects of curcumin on photosensitized human epidermal carcinoma A431 cells.
abstract: Photodynamic treatment (PDT) can elicit a diverse range of cellular responses, including apoptotic cell death. Previously, we showed that PDT stimulates caspase-3 activation and subsequent cleavage and activation of p21-activated kinase 2 (PAK2) in human epidermal carcinoma A431 cells. Curcumin, the yellow pigment of Curcuma longa, is known to have anti-oxidant and anti-inflammatory properties. In the present study, using Rose Bengal (RB) as the photosensitizer, we investigated the effect of curcumin on PDT-induced apoptotic events in human epidermal carcinoma A431 cells. We report that curcumin prevented PDT-induced JNK activation, mitochondrial release of cytochrome c, caspase-3 activation, and cleavage of PAK2. Using the cell permeable dye DCF-DA as an indicator of reactive oxygen species (ROS) generation, we found that both curcumin and ROS scavengers (i.e., l-histidine, a-tocopherol, mannitol) abolished PDT-stimulated intracellular oxidative stress. Moreover, all these PDT-induced apoptotic changes in cells could be blocked by singlet oxygen scavengers (i.e., l-histidine, a-tocopherol), but were not affected by the hydroxyl radical scavenger mannitol. In addition, we found that SP600125, a JNK-specific inhibitor, reduced PDT-induced JNK activation as well as caspase-3 activation, indicating that JNK activity is required for PDT-induced caspase activation. Collectively, these results demonstrate that singlet oxygen triggers JNK activation, cytochrome c release, caspase activation and subsequent apoptotic biochemical changes during PDT and show that curcumin is a potent inhibitor for this process.
authors.affiliation: Department of Bioscience Technology and Center for Nanotechnology, Chung Yuan Christian University, Chung Li, Taiwan, Republic of China. whchan@cycu.edu.tw
authors.forename: Wen-Hsiung
authors.initials: WH
authors.lastname: Chan
authors.forename: Hsin-Jung
authors.initials: HJ
authors.lastname: Wu
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002277:Carcinoma / Q000188:drug therapy / Q000378:metabolism*; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D003474:Curcumin / Q000494:pharmacology* / Q000627:therapeutic use; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D010778:Photochemotherapy; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000032:analysis; D024502:alpha-Tocopherol / Q000494:pharmacology; D054462:p21-Activated Kinases
chemical_list: D061945:Caspase Inhibitors; D017382:Reactive Oxygen Species; D045304:Cytochromes c; D011065:Poly(ADP-ribose) Polymerases; C515907:PAK2 protein, human; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases; D024502:alpha-Tocopherol; D003474:Curcumin