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Free Radic Biol Med. 2014 Nov;76:173-84. doi: 10.1016/j.freeradbiomed.2014.08.002. Epub 2014 Aug 20.

Nicotine mediates oxidative stress and apoptosis through cross talk between NOX1 and Bcl-2 in lung epithelial cells.

Author information

1
Department of Pediatrics, Children's Hospital, 1211 Geneva, Switzerland; Department of Pathology and Immunology, Medical School, and University of Geneva, Geneva, Switzerland.
2
Venetian Institute of Molecular Medicine, University of Padova, Padova, Italy.
3
Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
4
Department of Pediatrics, Children's Hospital, 1211 Geneva, Switzerland; Department of Pathology and Immunology, Medical School, and University of Geneva, Geneva, Switzerland. Electronic address: Constance.Barazzone@hcuge.ch.

Abstract

Nicotine contributes to the onset and progression of several pulmonary diseases. Among the various pathophysiological mechanisms triggered by nicotine, oxidative stress and cell death are reported in several cell types. We found that chronic exposure to nicotine (48h) induced NOX1-dependent oxidative stress and apoptosis in primary pulmonary cells. In murine (MLE-12) and human (BEAS-2B) lung epithelial cell lines, nicotine acted as a sensitizer to cell death and synergistically enhanced apoptosis when cells were concomitantly exposed to hyperoxia. The precise signaling pathway was investigated in MLE-12 cells in which NOX1 was abrogated by a specific inhibitor or stably silenced by shRNA. In the early phase of exposure (1h), nicotine mediated intracellular Ca(2+) fluxes and activation of protein kinase C, which in its turn activated NOX1, leading to cellular and mitochondrial oxidative stress. The latter triggered the intrinsic apoptotic machinery by modulating the expression of Bcl-2 and Bax. Overexpression of Bcl-2 completely prevented nicotine's detrimental effects, suggesting Bcl-2as a downstream key regulator in nicotine/NOX1-induced cell damage. These results suggest that NOX1 is a major contributor to the generation of intracellular oxidative stress induced by nicotine and might be an important molecule to target in nicotine-related lung pathologies.

KEYWORDS:

Alveolar epithelial type II cells; Apoptosis; Bcl-2; Free radicals; NOX1; Nicotine; Oxidative stress

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