title: Upregulation of connexin43 contributes to PX-12-induced oxidative cell death.
abstract: Thioredoxin (Trx) is a small redox protein that underlies aggressive tumor growth and resistance to chemotherapy. Inhibition of Trx with the chemical inhibitor PX-12 suppresses tumor growth and induces cell apoptosis. Currently, the mechanism underlying the therapeutic actions of PX-12 and the molecules influencing cell susceptibility to PX-12 are incompletely understood. Given that connexin43 (Cx43), a tumor suppressor, regulates tumor cell susceptibility to chemotherapy, we examined the possible involvement of Cx43 in PX-12-induced cell death. Exposure of cells to PX-12 led to a loss of cell viability, which was associated with the activation of oxidative sensitive c-Jun N-terminal kinase (JNK). Inhibition of JNK or supplement of cells with anti-oxidants prevented the cell-killing action of PX-12. The forced expression of Cx43 in normal and tumor cells increased cell sensitivity to PX-12-induced JNK activation and cell death. In contrast, the downregulation of Cx43 with siRNA or the suppression of gap junctions with chemical inhibitors attenuated JNK activation and enhanced cell resistance to PX-12. Further analysis revealed that PX-12 at low concentrations induced a JNK-dependent elevation in the Cx43 protein, which was also preventable by supplementing the cells with anti-oxidants. Our results thus indicate that Cx43 is a determinant in the regulation of cell susceptibility to PX-12 and that the upregulation of Cx43 may be an additional mechanism by which PX-12 exerts its anti-tumor actions.
authors.affiliation: Department of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, 409-3898, Japan.|Department of Urology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, Japan.|Department of Urology, Liaoning Cancer Hospital and Institute, Cancer Hospital of China Medical University, Shenyang, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.affiliation: Department of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, 409-3898, Japan.
authors.forename: Kun
authors.initials: K
authors.lastname: Gao
authors.affiliation: Department of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, 409-3898, Japan.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Chi
authors.affiliation: Department of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, 409-3898, Japan.
authors.forename: Xiling
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Urology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, Japan.
authors.forename: Takahiko
authors.initials: T
authors.lastname: Mitsui
authors.affiliation: Department of Molecular Signaling, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, 409-3898, Japan. yao@yamanashi.ac.jp.
authors.forename: Jian
authors.initials: J
authors.lastname: Yao
authors.affiliation: Department of Urology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Chuo, Yamanashi, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Takeda
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002450:Cell Communication / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects*; D002478:Cells, Cultured; D018031:Connexin 43 / Q000378:metabolism*; D004220:Disulfides / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D005786:Gene Expression Regulation; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology*; D007668:Kidney / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects*; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D013552:Swine
chemical_list: D018031:Connexin 43; D004220:Disulfides; D007093:Imidazoles; C412893:1-methylpropyl-2-imidazolyl disulfide; D007770:L-Lactate Dehydrogenase
keywords: Cx43; JNK; Oxidative stress; PX-12; Thioredoxin