title: Blockage of JNK pathway enhances arsenic trioxide-induced apoptosis in human keratinocytes.
abstract: Arsenic is well known as a carcinogen predisposing humans to some severe diseases and also as an effective medicine for treating acute promyelocytic leukemia, syphilis, and psoriasis. Multiple active mechanisms, including cell cycle arrest and apoptosis, have been proposed in therapy; however, the opposing effects of arsenic remain controversial. Our previous study found that arsenic trioxide (ATO)-induced activation of p21(WAF1/CIP1) (p21) led to A431 cell death through the antagonistic effects of the signaling of ERK1/2 and JNK1. In the current study, the inhibitory effects of JNK1 on ATO-induced p21 expression were explored. Over-expression of JNK1 in A431 cells could inhibit p21 expression, which was associated with HDAC1 and TGIF. Using the GST pull-down assay and fluorescence resonance energy transfer analysis, N-terminal domain (amino acids 1-108) of TGIF, critical to its binding with c-Jun, was found. Using reporter assays, requirement of the C-terminal domain (amino acids 138-272) of TGIF to suppress ATO-induced p21 expression was observed. Thus, the domains of TGIF that carried out its inhibitory effects on p21 were identified. Finally, treatment with JNK inhibitor SP600125 could enhance ATO-induced apoptosis of HaCaT keratinocytes by using flow cytometry.
authors.affiliation: Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan. huanghs@mail.ncku.edu.tw
authors.forename: Huei-Sheng
authors.initials: HS
authors.lastname: Huang
authors.forename: Zi-Miao
authors.initials: ZM
authors.lastname: Liu
authors.forename: Duang-Yang
authors.initials: DY
authors.lastname: Hong
mesh_terms: D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D000077237:Arsenic Trioxide; D001152:Arsenicals; D045744:Cell Line, Tumor; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015603:Keratinocytes / Q000187:drug effects* / Q000201:enzymology* / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000502:physiology; D048055:Mitogen-Activated Protein Kinase 8 / Q000037:antagonists & inhibitors / Q000378:metabolism; D010087:Oxides / Q000633:toxicity*; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology
chemical_list: D000873:Anthracenes; D001152:Arsenicals; D010087:Oxides; C432165:pyrazolanthrone; D048031:JNK Mitogen-Activated Protein Kinases; D048055:Mitogen-Activated Protein Kinase 8; D000077237:Arsenic Trioxide