title: Depletion of end-binding protein 1 (EB1) promotes apoptosis of human non-small-cell lung cancer cells via reactive oxygen species and Bax-mediated mitochondrial dysfunction.
abstract: Although end-binding protein 1 (EB1) is well known to regulate microtubule dynamics, the role of EB1 in apoptosis of non-small cell lung cancer (NSCLC) is poorly understood. Here, we investigated the molecular mechanism by which EB1 regulates apoptosis in H460, A549, and H1299 cells. Depletion of EB1 in A549 and H1299 cells, which express high levels of EB1, induced cell death in a p53-independent manner through over-production of reactive oxygen species (ROS) and Bax induction. This phenomenon was potentiated in radiation-treated EB1-knockdown cells and was largely blocked by N-acetyl-L-cysteine, a scavenger of ROS. ROS accelerated the activation of nuclear factor-kappa B (NF-κB) to promote transcriptional activity of Bax, an action that was accompanied by cytochrome c translocation and apoptosis-inducing factor (AIF) release. The NF-κB inhibitor, BAY 11-7082, potently inhibited the apoptosis induced by EB1 knockdown and radiation treatment, in association with diminished activity of the mitochondrial death pathway. Conversely, ectopic overexpression of EB1 in H460 cells, which express low levels of EB1, remarkably abrogated radiation-induced apoptosis and NF-κB-mediated mitochondrial dysfunction. Our data provide the first demonstration that down-regulation of EB1 promotes NSCLC cell death by inducing ROS-mediated, NF-κB-dependent Bax signaling cascades, a process in which cytochrome c and AIF play important roles, indicating a potential therapeutic benefit of EB1 in lung cancer.
authors.affiliation: Division of Radiation Cancer Biology, Korea Institute of Radiological and Medical Sciences, Seoul 139-706, Republic of Korea.
authors.forename: Min-Jung
authors.initials: MJ
authors.lastname: Kim
authors.forename: Hong Shik
authors.initials: HS
authors.lastname: Yun
authors.forename: Eun-Hee
authors.initials: EH
authors.lastname: Hong
authors.forename: Su-Jae
authors.initials: SJ
authors.lastname: Lee
authors.forename: Jeong-Hwa
authors.initials: JH
authors.lastname: Baek
authors.forename: Chang-Woo
authors.initials: CW
authors.lastname: Lee
authors.forename: Ji-Hye
authors.initials: JH
authors.lastname: Yim
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Kim
authors.forename: Jong Kuk
authors.initials: JK
authors.lastname: Park
authors.forename: Hong-Duck
authors.initials: HD
authors.lastname: Um
authors.forename: Sang-Gu
authors.initials: SG
authors.lastname: Hwang
mesh_terms: D017209:Apoptosis / Q000235:genetics / Q000528:radiation effects; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism*; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D051028:bcl-2-Associated X Protein / Q000378:metabolism*
chemical_list: C500985:MAPRE1 protein, human; D008869:Microtubule-Associated Proteins; D017382:Reactive Oxygen Species; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein
keywords: AIF; Apoptosis; Bax; EB1; Mitochondrial ROS; N-acetyl cysteine; NAC; NF-κB; NSCLC; PARP; ROS; Radiation; apoptosis inducing factor; end-binding protein 1; non-small-cell lung cancer; nuclear factor-kappa B; poly (ADP-ribose) polymerase; reactive oxygen species; siRNA; small interfering RNA