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Differential induction of heme oxygenase‐1 against nicotine‐induced cytotoxicity via the PI3K, MAPK, and NF‐kappa B pathways in immortalized and malignant human oral keratinocytes
Author(s) -
Lee HwaJeong,
Lee Jun,
Min SeungKi,
Guo HanYoung,
Lee SunKyung,
Kim HyungRyong,
Pae HyunOck,
Chung HunTaeg,
Hong SeungHeon,
Lee SukKeun,
Kim EunCheol
Publication year - 2008
Publication title -
journal of oral pathology and medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 83
eISSN - 1600-0714
pISSN - 0904-2512
DOI - 10.1111/j.1600-0714.2007.00616.x
Subject(s) - heme oxygenase , cytotoxicity , mapk/erk pathway , heme , nfkb1 , pi3k/akt/mtor pathway , cancer research , chemistry , nf κb , nicotine , cell culture , apoptosis , microbiology and biotechnology , signal transduction , biology , medicine , in vitro , biochemistry , enzyme , gene , genetics , transcription factor
BACKGROUND: Heme oxygenase‐1 (HO‐1) exhibits cytoprotective effects in many different cell types and is induced by nicotine exposure in human gingival fibroblasts. However, the role of HO‐1 in cancer cells exposed to nicotine has not previously been described. METHODS: We investigated the effects of nicotine on HO‐1 protein expression and cell viability in immortalized (IHOK) and malignant (HN12) human oral keratinocyte cells using the 3,4,5‐dimethylthiazol‐2‐yl‐2,5‐diphenyl tetrazolium bromide assay and Western blotting. We also examined the involvement of the phosphoinositide‐3‐kinase (PI3K), mitogen‐activated protein kinase (MAPK), and nuclear factor‐κB (NF‐κB) signaling pathways in nicotine‐induced cytotoxicity and HO‐1 levels in IHOK and HN12 cells. RESULTS: Nicotine‐induced HO‐1 production and had cytotoxic effects on cells in both a concentration‐ and time‐dependent manner. Nicotine‐induced cytotoxicity and accumulation of HO‐1 were greater in IHOK cells than in HN12 cells. Molecular inhibitors of the ERK, p38 MAP kinase, PI3 K, and NF‐κB signaling pathways blocked the cytotoxic effects and induction of HO‐1 expression by nicotine. Treatment with antioxidants (bilirubin, N ‐acetylcysteine) protected cells against nicotine‐induced cytotoxicity and blocked the upregulation of HO‐1, the effects of which were more pronounced in IHOK cells than in HN12 cells. CONCLUSIONS: Collectively, these results suggest that HO‐1 plays a principal role in the protective response to nicotine in oral cancer and immortalized keratinocytes. Moreover, the addition of exogenous antioxidants may help to protect oral epithelial cells as chemopreventive agents against nicotine‐induced oxidative stress.