NF-kappaB mediates the survival of human bronchial epithelial cells exposed to cigarette smoke extract

Xiang-de Liu, Shinsaku Togo, Mona Al-Mugotir, Huijung Kim, QiuHong Fang, Tetsu Kobayashi, XingQi Wang, Lijun Mao, Peter Bitterman, Stephen Rennard

Research output: Contribution to journalArticle

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Abstract

Background: We have previously reported that low concentrations of cigarette smoke extract induce DNA damage without leading to apoptosis or necrosis in human bronchial epithelial cells (HBECs), and that IL-6/STAT3 signaling contributes to the cell survival. Since NF-κB is also involved in regulating apoptosis and cell survival, the current study was designed to investigate the role of NF-κB in mediating cell survival in response to cigarette smoke exposure in HBECs.Methods: Both the pharmacologic inhibitor of NF-κB, curcumin, and RNA interference targeting p65 were used to block NF-κB signaling in HBECs. Apoptosis and cell survival were then assessed by various methods including COMET assay, LIVE/DEAD Cytotoxicity/Viability assay and colony formation assay.Results: Cigarette smoke extract (CSE) caused DNA damage and cell cycle arrest in S phase without leading to apoptosis in HBECs as evidenced by TUNEL assay, COMET assay and DNA content assay. CSE stimulated NF-κB -DNA binding activity and up-regulated Bcl-XL protein in HBECs. Inhibition of NF-κB by the pharmacologic inhibitor curcumin (20 μM) or suppression of p65 by siRNA resulted in a significant increase in cell death in response to cigarette smoke exposure. Furthermore, cells lacking p65 were incapable of forming cellular colonies when these cells were exposed to CSE, while they behaved normally in the regular culture medium.Conclusion: The current study demonstrates that CSE activates NF-κB and up-regulates Bcl-XL through NF-kB activation in HBECs, and that CSE induces cell death in cells lacking p65. These results suggest that activation of NF-κB regulates cell survival following DNA damage by cigarette smoke in human bronchial epithelial cells.

Original languageEnglish (US)
Article number66
JournalRespiratory Research
Volume9
DOIs
StatePublished - Sep 23 2008

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NF-kappa B
Smoke
Tobacco Products
Epithelial Cells
Cell Survival
Apoptosis
DNA Damage
Curcumin
Cell Death
B-Form DNA
In Situ Nick-End Labeling
RNA Interference
Cell Cycle Checkpoints
S Phase
Small Interfering RNA
Culture Media
Interleukin-6
Necrosis
Up-Regulation
DNA

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine

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NF-kappaB mediates the survival of human bronchial epithelial cells exposed to cigarette smoke extract. / Liu, Xiang-de; Togo, Shinsaku; Al-Mugotir, Mona; Kim, Huijung; Fang, QiuHong; Kobayashi, Tetsu; Wang, XingQi; Mao, Lijun; Bitterman, Peter; Rennard, Stephen.

In: Respiratory Research, Vol. 9, 66, 23.09.2008.

Research output: Contribution to journalArticle

Liu, X, Togo, S, Al-Mugotir, M, Kim, H, Fang, Q, Kobayashi, T, Wang, X, Mao, L, Bitterman, P & Rennard, S 2008, 'NF-kappaB mediates the survival of human bronchial epithelial cells exposed to cigarette smoke extract', Respiratory Research, vol. 9, 66. https://doi.org/10.1186/1465-9921-9-66
Liu, Xiang-de ; Togo, Shinsaku ; Al-Mugotir, Mona ; Kim, Huijung ; Fang, QiuHong ; Kobayashi, Tetsu ; Wang, XingQi ; Mao, Lijun ; Bitterman, Peter ; Rennard, Stephen. / NF-kappaB mediates the survival of human bronchial epithelial cells exposed to cigarette smoke extract. In: Respiratory Research. 2008 ; Vol. 9.
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AU - Togo, Shinsaku

AU - Al-Mugotir, Mona

AU - Kim, Huijung

AU - Fang, QiuHong

AU - Kobayashi, Tetsu

AU - Wang, XingQi

AU - Mao, Lijun

AU - Bitterman, Peter

AU - Rennard, Stephen

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N2 - Background: We have previously reported that low concentrations of cigarette smoke extract induce DNA damage without leading to apoptosis or necrosis in human bronchial epithelial cells (HBECs), and that IL-6/STAT3 signaling contributes to the cell survival. Since NF-κB is also involved in regulating apoptosis and cell survival, the current study was designed to investigate the role of NF-κB in mediating cell survival in response to cigarette smoke exposure in HBECs.Methods: Both the pharmacologic inhibitor of NF-κB, curcumin, and RNA interference targeting p65 were used to block NF-κB signaling in HBECs. Apoptosis and cell survival were then assessed by various methods including COMET assay, LIVE/DEAD Cytotoxicity/Viability assay and colony formation assay.Results: Cigarette smoke extract (CSE) caused DNA damage and cell cycle arrest in S phase without leading to apoptosis in HBECs as evidenced by TUNEL assay, COMET assay and DNA content assay. CSE stimulated NF-κB -DNA binding activity and up-regulated Bcl-XL protein in HBECs. Inhibition of NF-κB by the pharmacologic inhibitor curcumin (20 μM) or suppression of p65 by siRNA resulted in a significant increase in cell death in response to cigarette smoke exposure. Furthermore, cells lacking p65 were incapable of forming cellular colonies when these cells were exposed to CSE, while they behaved normally in the regular culture medium.Conclusion: The current study demonstrates that CSE activates NF-κB and up-regulates Bcl-XL through NF-kB activation in HBECs, and that CSE induces cell death in cells lacking p65. These results suggest that activation of NF-κB regulates cell survival following DNA damage by cigarette smoke in human bronchial epithelial cells.

AB - Background: We have previously reported that low concentrations of cigarette smoke extract induce DNA damage without leading to apoptosis or necrosis in human bronchial epithelial cells (HBECs), and that IL-6/STAT3 signaling contributes to the cell survival. Since NF-κB is also involved in regulating apoptosis and cell survival, the current study was designed to investigate the role of NF-κB in mediating cell survival in response to cigarette smoke exposure in HBECs.Methods: Both the pharmacologic inhibitor of NF-κB, curcumin, and RNA interference targeting p65 were used to block NF-κB signaling in HBECs. Apoptosis and cell survival were then assessed by various methods including COMET assay, LIVE/DEAD Cytotoxicity/Viability assay and colony formation assay.Results: Cigarette smoke extract (CSE) caused DNA damage and cell cycle arrest in S phase without leading to apoptosis in HBECs as evidenced by TUNEL assay, COMET assay and DNA content assay. CSE stimulated NF-κB -DNA binding activity and up-regulated Bcl-XL protein in HBECs. Inhibition of NF-κB by the pharmacologic inhibitor curcumin (20 μM) or suppression of p65 by siRNA resulted in a significant increase in cell death in response to cigarette smoke exposure. Furthermore, cells lacking p65 were incapable of forming cellular colonies when these cells were exposed to CSE, while they behaved normally in the regular culture medium.Conclusion: The current study demonstrates that CSE activates NF-κB and up-regulates Bcl-XL through NF-kB activation in HBECs, and that CSE induces cell death in cells lacking p65. These results suggest that activation of NF-κB regulates cell survival following DNA damage by cigarette smoke in human bronchial epithelial cells.

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