title: Cadmium induces intracellular Ca2+- and H2O2-dependent apoptosis through JNK- and p53-mediated pathways in skin epidermal cell line.
abstract: Cadmium is a toxic heavy metal and has been widely used in industry. The skin is an important target for this metal. The mechanisms by which cadmium leads to damage to the skin are unclear at present. The aims of this study were to examine whether cadmium induces apoptosis in mouse skin epidermal cell line, JB6 Cl41 cells, and to investigate the cellular mechanisms by which cadmium causes cytotoxicity in the cells. The present study showed that cadmium induced cell death by apoptosis in a dose-dependent manner, as proven by the appearance of cell shrinkage, the increase of Annexin V positively stained cells, and the formation of nuclear DNA ladders. Cadmium-induced apoptosis involved a mitochondria-mediated mechanism but not caspase-dependent pathway in that the critical apoptotic events induced by cadmium, such as the decrease of Bcl-2/Bcl-xL, the increase of GADD45alpha, and the nuclear translocation of apoptosis inducing factor, were not affected by the inhibition of executive caspases. In contrast, blockage of p53 and JNK by pharmacological inhibitors or small interference RNA transfection suppressed the cadmium-induced apoptosis with the concomitant inhibition of antiapoptotic Bcl-2 family proteins and GADD45alpha, respectively. Furthermore, the activation of p53 and JNK and their downstream proteins in cadmium-exposed cells were inhibited by individual treatment with catalase and Bapta-acetoxymethyl. These results suggest that cadmium induces apoptosis via the activation of JNK- and p53-mediated signaling, where calcium ion and hydrogen peroxide act as the pivotal mediators of the apoptotic signaling.
authors.affiliation: Graduate Center for Toxicology, College of Medicine, University of Kentucky, Lexington, Kentucky 40536-0305, USA.
authors.forename: Young-Ok
authors.initials: YO
authors.lastname: Son
authors.forename: Jeong-Chae
authors.initials: JC
authors.lastname: Lee
authors.forename: J Andrew
authors.initials: JA
authors.lastname: Hitron
authors.forename: Jingju
authors.initials: J
authors.lastname: Pan
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Zhang
authors.forename: Xianglin
authors.initials: X
authors.lastname: Shi
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D019256:Cadmium Chloride / Q000633:toxicity*; D002118:Calcium / Q000378:metabolism*; D020169:Caspases / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004817:Epidermis / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D006861:Hydrogen Peroxide / Q000378:metabolism*; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology / Q000473:pathology; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D051020:bcl-X Protein / Q000378:metabolism; D000097642:GADD45 Proteins
chemical_list: D000975:Antioxidants; D051033:Apoptosis Inducing Factor; D019256:Cadmium Chloride; D002118:Calcium; D020169:Caspases; D018797:Cell Cycle Proteins; D006861:Hydrogen Peroxide; D048031:JNK Mitogen-Activated Protein Kinases; D009687:Nuclear Proteins; D047428:Protein Kinase Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051020:bcl-X Protein; C494812:Bcl2l1 protein, mouse; C499072:Gadd45a protein, mouse; D000097642:GADD45 Proteins; C494830:AIFM1 protein, mouse