title: Oxidative stress mediates chemical hypoxia-induced injury and inflammation by activating NF-κb-COX-2 pathway in HaCaT cells.
abstract: Hypoxia of skin is an important physiopathological process in many diseases, such as pressure ulcer, diabetic ulcer, and varicose ulcer. Although cellular injury and inflammation have been involved in hypoxia-induced dermatic injury, the underlying mechanisms remain largely unknown. This study was conducted to investigate the effects of cobalt chloride (CoCl(2)), a hypoxia-mimicking agent, on human skin keratinocytes (HaCaT cells) and to explore the possible molecular mechanisms. Exposure of HaCaT cells to CoCl(2) reduced cell viability and caused overproduction of reactive oxygen species (ROS) and oversecretion of interleukin-6 (IL-6) and interleukin-8 (IL-8). Importantly, CoCl(2) exposure elicited overexpression of cyclooxygenase-2 (COX-2) and phosphorylation of nuclear factor-kappa B (NF-κB) p65 subunit. Inhibition of COX-2 by NS-398, a selective inhibitor of COX-2, significantly repressed the cytotoxicity, as well as secretion of IL-6 and IL-8 induced by CoCl(2). Inhibition of NF-κB by PDTC (a selective inhibitor of NF-κB) or genetic silencing of p65 by RNAi (Si-p65), attenuated not only the cytotoxicity and secretion of IL-6 and IL-8, but also overexpression of COX-2 in CoCl(2)-treated HaCaT cells. Neutralizing anti-IL-6 or anti-IL-8 antibody statistically alleviated CoCl(2)-induced cytotoxicity in HaCaT cells. N-acetyl-L-cysteine (NAC), a well characterized ROS scavenger, obviously suppressed CoCl(2)-induced cytotoxicity in HaCaT cells, as well as secretion of IL-6 and IL-8. Additionally, NAC also repressed overexpression of COX-2 and phosphorylation of NF- B κ p65 subunit induced by CoCl(2) in HaCaT cells. In conclusion, our results demonstrated that oxidative stress mediates chemical hypoxia-induced injury and inflammatory response through activation of NF-κB-COX-2 pathway in HaCaT cells.
authors.affiliation: Department of Physiology, Zhongshan School of Medicine, Sun Yat-sen University, Guangdong, People's Republic of China.
authors.forename: Chuntao
authors.initials: C
authors.lastname: Yang
authors.forename: Hongzhong
authors.initials: H
authors.lastname: Ling
authors.forename: Meifen
authors.initials: M
authors.lastname: Zhang
authors.forename: Zhanli
authors.initials: Z
authors.lastname: Yang
authors.forename: Xiuyu
authors.initials: X
authors.lastname: Wang
authors.forename: Fanqin
authors.initials: F
authors.lastname: Zeng
authors.forename: Chuhuai
authors.initials: C
authors.lastname: Wang
authors.forename: Jianqiang
authors.initials: J
authors.lastname: Feng
mesh_terms: D015687:Cell Hypoxia / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003035:Cobalt; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D006801:Humans; D007249:Inflammation / Q000139:chemically induced; D015850:Interleukin-6 / Q000096:biosynthesis / Q000378:metabolism; D016209:Interleukin-8 / Q000096:biosynthesis / Q000378:metabolism; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism*; D009578:Nitrobenzenes / Q000494:pharmacology; D018384:Oxidative Stress; D010766:Phosphorylation; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction; D012867:Skin / Q000473:pathology / Q000503:physiopathology; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: D016861:Cyclooxygenase Inhibitors; D015850:Interleukin-6; D016209:Interleukin-8; D016328:NF-kappa B; D009578:Nitrobenzenes; D017382:Reactive Oxygen Species; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D003035:Cobalt; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; C018021:cobaltous chloride