Cigarette smoke-induced cell death of a spermatocyte cell line can be prevented by inactivating the Aryl hydrocarbon receptor

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor whose physiological function is poorly understood. The AhR is highly expressed in barrier organs such as the skin, intestine and lung. The lungs are continuously exposed to environmental pollutants such as cigarette smoke (CS) that can induce cell death mechanisms such as apoptosis, autophagy and endoplasmic reticulum (ER) stress. CS also contains toxicants that are AhR ligands. We have previously shown that the AhR protects against apoptosis, but whether the AhR also protects against autophagy or ER stress is not known. Using cigarette smoke extract (CSE) as our in vitro surrogate of environmental tobacco exposure, we first assessed the conversion of LC3I to LC3II, a classic feature of both autophagic and ER stress-mediated cell death pathways. LC3II was elevated in CSE-exposed lung structural cells (mouse lung fibroblasts [MLFs], MLE12 and A549 cells) when AhR was absent. However, this heightened LC3II expression could not be explained by increased expression of key autophagy genes (Gabarapl1, Becn1, Map1lc3b), upregulation of upstream autophagic machinery (Atg5-12, Atg3) or by impaired autophagic flux, suggesting that LC3II may be autophagy-independent. This was further supported by the absence of autophagosomes in Ahr-/- lung cells. However, Ahr-/- lung cells had widespread ER-dilation, elevated expression of the ER stress markers CHOP and GADD34 and an accumulation of ubiquitinated proteins. These findings collectively illustrate a novel role for the AhR in attenuating ER stress by a mechanism that may be autophagy-independent.

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290 ACTIVATION OF THE ARYL HYDROCARBON RECEPTOR IS ASSOCIATED WITH CIGARETTE SMOKE, POOR PROGNOSIS AND CANCER CELL INVASION IN RENAL CELL CARCINOMA

European Urology Supplements ◽

10.1016/s1569-9056(10)60289-8 ◽

2010 ◽

Vol 9 (2) ◽

pp. 118

Author(s):

M. Ishida ◽

S. Mikami ◽

T. Kosaka ◽

H. Kono ◽

E. Kikuchi ◽

...

Keyword(s):

Renal Cell Carcinoma ◽

Aryl Hydrocarbon Receptor ◽

Cell Carcinoma ◽

Cigarette Smoke ◽

Cancer Cell ◽

Cell Invasion ◽

Renal Cell ◽

Poor Prognosis ◽

Cancer Cell Invasion ◽

Aryl Hydrocarbon

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RelB attenuates cigarette smoke extract-induced apoptosis in association with transcriptional regulation of the aryl hydrocarbon receptor

Free Radical Biology and Medicine ◽

10.1016/j.freeradbiomed.2017.02.045 ◽

2017 ◽

Vol 108 ◽

pp. 19-31 ◽

Cited By ~ 12

Author(s):

Matthew Iu ◽

Michela Zago ◽

Angela Rico de Souza ◽

Manuella Bouttier ◽

Swati Pareek ◽

...

Keyword(s):

Transcriptional Regulation ◽

Aryl Hydrocarbon Receptor ◽

Cigarette Smoke ◽

Cigarette Smoke Extract ◽

Aryl Hydrocarbon ◽

Induced Apoptosis

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Polycyclic Aromatic Hydrocarbons Can Trigger Hepatocyte Release of Extracellular Vesicles by Various Mechanisms of Action Depending on Their Affinity for the Aryl Hydrocarbon Receptor

Toxicological Sciences ◽

10.1093/toxsci/kfz157 ◽

2019 ◽

Vol 171 (2) ◽

pp. 443-462 ◽

Cited By ~ 9

Author(s):

Nettie van Meteren ◽

Dominique Lagadic-Gossmann ◽

Martine Chevanne ◽

Isabelle Gallais ◽

Dimitri Gobart ◽

...

Keyword(s):

Cell Death ◽

Transcription Factor ◽

Polycyclic Aromatic Hydrocarbons ◽

Cell Membrane ◽

Aryl Hydrocarbon Receptor ◽

Extracellular Vesicles ◽

Aromatic Hydrocarbons ◽

Aryl Hydrocarbon ◽

Polycyclic Aromatic ◽

Cell Membrane Fluidity

Abstract Extracellular vesicles (EVs) are membrane-enclosed nanostructures released by cells into the extracellular environment. As major actors of physiological intercellular communication, they have been shown to be pathogenic mediators of several liver diseases. Extracellular vesicles also appear to be potential actors of drug-induced liver injury but nothing is known concerning environmental pollutants. We aimed to study the impact of polycyclic aromatic hydrocarbons (PAHs), major contaminants, on hepatocyte-derived EV production, with a special focus on hepatocyte death. Three PAHs were selected, based on their presence in food and their affinity for the aryl hydrocarbon receptor (AhR): benzo[a]pyrene (BP), dibenzo[a,h]anthracene (DBA), and pyrene (PYR). Treatment of primary rat and WIF-B9 hepatocytes by all 3 PAHs increased the release of EVs, mainly comprised of exosomes, in parallel with modifying exosome protein marker expression and inducing apoptosis. Moreover, PAH treatment of rodents for 3 months also led to increased EV levels in plasma. The EV release involved CYP metabolism and the activation of the transcription factor, the AhR, for BP and DBA and another transcription factor, the constitutive androstane receptor, for PYR. Furthermore, all PAHs increased cholesterol levels in EVs but only BP and DBA were able to reduce the cholesterol content of total cell membranes. All cholesterol changes very likely participated in the increase in EV release and cell death. Finally, we studied changes in cell membrane fluidity caused by BP and DBA due to cholesterol depletion. Our data showed increased cell membrane fluidity, which contributed to hepatocyte EV release and cell death.

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E-cigarette Aerosol Condensate Enhances Metabolism of Benzo(a)pyrene to Genotoxic Products, and Induces CYP1A1 and CYP1B1, Likely by Activation of the Aryl Hydrocarbon Receptor

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16142468 ◽

2019 ◽

Vol 16 (14) ◽

pp. 2468 ◽

Cited By ~ 3

Author(s):

Yuan-Wan Sun ◽

Wieslawa Kosinska ◽

Joseph B. Guttenplan

Keyword(s):

Aryl Hydrocarbon Receptor ◽

Cell Line ◽

Tobacco Smoke ◽

Genotoxic Effects ◽

Aryl Hydrocarbon ◽

Hydrolysis Products ◽

Spontaneous Hydrolysis ◽

Tobacco Carcinogen ◽

Keratinocyte Cell ◽

Carcinogenic Metabolite

E-cigarette aerosol contains lower levels of most known carcinogens than tobacco smoke, but many users of e-cigarettes are also smokers, and these individuals may be vulnerable to possible promoting and/or cocarcinogenic effects of e-cigarettes. We investigated the possibility that a condensate of e-cigarette aerosol (EAC) enhances the metabolism of the tobacco carcinogen, benzo(a)pyrene (BaP), to genotoxic products in a human oral keratinocyte cell line. Cells were pretreated with EAC from two popular e-cigs and then with BaP. Metabolism to its ultimate carcinogenic metabolite, anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydro B[a]P (BPDE), was assayed by measuring isomers of its spontaneous hydrolysis products, BaP tetrols. The pretreatment of cells with EAC enhanced the rate of BaP tetrol formation several fold. Pretreatment with the e-liquid resulted in a smaller enhancement. The treatment of cells with EAC induced CYP1A1/1B1 mRNA and protein. The enhancement of BaP tetrol formation was inhibited by the aryl hydrocarbon receptor (AhR) inhibitor, α-napthoflavone, indicating EAC likely induces CYP1A1/1B1 and enhances BaP metabolism by activating the AhR. To our knowledge, this is first report demonstrating that e-cigarettes can potentiate the genotoxic effects of a tobacco smoke carcinogen.

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Cytotoxic effects of cigarette smoke extract on an alveolar type II cell-derived cell line

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.2001.281.2.l509 ◽

2001 ◽

Vol 281 (2) ◽

pp. L509-L516 ◽

Cited By ~ 128

Author(s):

Yuma Hoshino ◽

Tadashi Mio ◽

Sonoko Nagai ◽

Hiroyuki Miki ◽

Isao Ito ◽

...

Keyword(s):

Cell Death ◽

Cell Line ◽

Cigarette Smoke ◽

A549 Cells ◽

Cigarette Smoke Extract ◽

Alveolar Type ◽

Type Ii ◽

Cytotoxic Effects ◽

Alveolar Type Ii Cell ◽

Type Ii Cell

Injury of the alveolar epithelium by cigarette smoke is presumed to be an important process in the pathogenesis of smoking-related pulmonary diseases. We investigated the cytotoxic effects of cigarette smoke extract (CSE) on an alveolar type II cell-derived cell line (A549). CSE caused apoptosis at concentrations of 5% or less and necrosis at 10% or more. When CSE was exposed to air before application to A549 cells, the cytotoxic effects were attenuated. CSE caused cell death without direct contact with the cells. Acrolein and hydrogen peroxide, two major volatile factors in cigarette smoke, caused cell death in a similar manner. Aldehyde dehydrogenase, a scavenger of aldehydes, and N-acetylcysteine, a scavenger of oxidants and aldehydes, completely inhibited CSE-induced apoptosis. CSE and acrolein increased intracellular oxidant activity. In conclusion, apoptosis of alveolar epithelial cells may be one of the mechanisms of lung injury induced by cigarette smoking. This cytotoxic effect might be due to an interaction between aldehydes and oxidants present in CSE or formed in CSE-exposed cells.

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Down-Regulation of p23 in Normal Lung Epithelial Cells Reduces Toxicities From Exposure to Benzo[a]pyrene and Cigarette Smoke Condensate via an Aryl Hydrocarbon Receptor-Dependent Mechanism

Toxicological Sciences ◽

10.1093/toxsci/kfy234 ◽

2018 ◽

Vol 167 (1) ◽

pp. 239-248 ◽

Cited By ~ 3

Author(s):

Jinyun Chen ◽

Poonam Yakkundi ◽

William K Chan

Keyword(s):

Epithelial Cells ◽

Aryl Hydrocarbon Receptor ◽

Cigarette Smoke ◽

Lung Epithelial Cells ◽

Normal Lung ◽

Cigarette Smoke Condensate ◽

Down Regulation ◽

Protein Levels ◽

Aryl Hydrocarbon ◽

Lung Epithelial

Abstract The aryl hydrocarbon receptor (AHR) is a ligand-activated signaling molecule which controls tumor growth and metastasis, T cell differentiation, and liver development. Expression levels of this receptor protein is sensitive to the cellular p23 protein levels in immortalized cancer cell lines. As little as 30% reduction of the p23 cellular content can suppress the AHR function. Here we reported that down-regulation of the p23 protein content in normal, untransformed human bronchial/tracheal epithelial cells to 48% of its content also suppresses the AHR protein levels to 54% of its content. This p23-mediated suppression of AHR is responsible for the suppression of (1) the ligand-dependent induction of the cyp1a1 gene transcription; (2) the benzo[a]pyrene- or cigarette smoke condensate-induced CYP1A1 enzyme activity, and (3) the benzo[a]pyrene and cigarette smoke condensate-mediated production of reactive oxygen species. Reduction of the p23 content does not alter expression of oxidative stress genes and production of PGE2. Down regulation of p23 suppresses the AHR protein levels in two other untransformed cell types, namely human breast MCF-10A and mouse immune regulatory Tr1 cells. Collectively, down-regulation of p23 suppresses the AHR protein levels in normal and untransformed cells and can in principle protect our lung epithelial cells from AHR-dependent oxidative damage caused by exposure to agents from environment and cigarette smoking.

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