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Smoking-induced upregulation of AKR1B10 expression in the airway epithelium of healthy individuals.

ABSTRACT: BACKGROUND:The aldo-keto reductase (AKR) gene superfamily codes for monomeric, soluble reduced nicotinamide adenine dinucleotide phosphate-dependent oxidoreductases that mediate elimination reactions. AKR1B10, an AKR that eliminates retinals, has been observed as upregulated in squamous metaplasia and non-small cell lung cancer and has been suggested as a diagnostic marker specific to tobacco-related carcinogenesis. We hypothesized that upregulation of AKR1B10 expression may be initiated in healthy smokers prior to the development of evidence of lung cancer. METHODS:Expression of AKR1B10 was assessed at the mRNA level using microarrays with TaqMan confirmation in the large airway epithelium (21 healthy nonsmokers, 31 healthy smokers) and small airway epithelium (51 healthy nonsmokers, 58 healthy smokers) obtained by fiberoptic bronchoscopy and brushing. RESULTS:Compared with healthy nonsmokers, AKR1B10 mRNA levels were significantly upregulated in both large and small airway epithelia of healthy smokers. Consistent with the mRNA data, AKR1B10 protein was significantly upregulated in the airway epithelium of healthy smokers as assessed by Western blot analysis and immunohistochemistry, with AKR1B10 expressed in both differentiated and basal cells. Finally, cigarette smoke extract mediated upregulation of AKR1B10 in airway epithelial cells in vitro, and transfection of AKR1B10 into airway epithelial cells enhanced the conversion of retinal to retinol. CONCLUSIONS:Smoking per se mediates upregulation of AKR1B10 expression in the airway epithelia of healthy smokers with no evidence of lung cancer. In the context of these observations and the link of AKR1B10 to the metabolism of retinals and to lung cancer, the smoking-induced upregulation of AKR1B10 may be an early process in the multiple events leading to lung cancer.

SUBMITTER: Wang R

PROVIDER: S-EPMC2998206 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

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Smoking-induced upregulation of AKR1B10 expression in the airway epithelium of healthy individuals.

Wang Rui R Wang Guoqing G Ricard Megan J MJ Ferris Barbara B Strulovici-Barel Yael Y Salit Jacqueline J Hackett Neil R NR Gudas Lorraine J LJ Crystal Ronald G RG

Chest 20100812 6

<h4>Background</h4>The aldo-keto reductase (AKR) gene superfamily codes for monomeric, soluble reduced nicotinamide adenine dinucleotide phosphate-dependent oxidoreductases that mediate elimination reactions. AKR1B10, an AKR that eliminates retinals, has been observed as upregulated in squamous metaplasia and non-small cell lung cancer and has been suggested as a diagnostic marker specific to tobacco-related carcinogenesis. We hypothesized that upregulation of AKR1B10 expression may be initiated ...[more]

PMID: 20705797

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Project description:The aldokatoreductases (AKRs) represent a gene superfamily that code for monomeric, soluble NAD(P)H-dependent oxidoreductases that mediate elimination reactions. AKR1B10, an AKR that functions to eliminate retinals, has been observed to be upregulated in squamous metaplasma and non small cell lung cancer, and has been suggested as a diagnostic marker specific to tobacco-related carcinogenesis. In the context of the link of smoking and lung cancer and the enhanced expression of AKR1B10 expression in lung cancer, we hypothesize that enhanced expression of AKR1B10 may be initiated in healthy smokers, prior to the development of any evidence of lung cancer. For this purpose, expression of AKR1B10 was assessed at the mRNA level using microarrays in the large airway epithelium (21 healthy nonsmokers, 31 health smokers) and small airway epithelium (51 healthy nonsmokers, 58 healthy smokers) obtained by fiberoptic bronchoscopy and brushing, as well as assessment in a subset of this population by TaqMan PCR and in endobronchial biopsies by Western analysis and immunohistochemistry. Compared to healthy nonsmokers, ARK1B10 mRNA levels were markedly upregulated in both the large and small airway epithelium of healthy smokers (large airway microarray p<0.0001, small airway p<0.0001; TaqMan large airway, p<0.02, small airway p<0.01). Consistent with the mRNA data, AKR1B10 protein was significantly upregulated in the airway epithelium of healthy smokers as assessed by Western analysis and by immunohistochemistry, with AKR1B10 expressed in both differentiated and basal cells of the normal epithelium. Finally, cigarette smoke extract mediated up-regulation of AKR1B10 in airway epithelial cells in vitro. Thus, smoking per se mediates up-regulation of AKR1B10 expression in the airway epithelium of healthy smokers with no evidence of lung cancer. In the context of these observations, and the link of AKR1B10 to the metabolism of retinals and to lung cancer, the smoking-induced up-regulation of AKR1B10 may be an early process in the multiple events leading to the develop of lung cancer.

Project description:Cigarette smoking is a leading cause of preventable death and a significant cause of lung cancer and chronic obstructive pulmonary disease. Prior studies have demonstrated that smoking creates a field of molecular injury throughout the airway epithelium exposed to cigarette smoke. We have previously characterized gene expression in the bronchial epithelium of never smokers and identified the gene expression changes that occur in the mainstem bronchus in response to smoking. In this study, we explored relationships in whole-genome gene expression between extrathorcic (buccal and nasal) and intrathoracic (bronchial) epithelium in healthy current and never smokers.Using genes that have been previously defined as being expressed in the bronchial airway of never smokers (the "normal airway transcriptome"), we found that bronchial and nasal epithelium from non-smokers were most similar in gene expression when compared to other epithelial and nonepithelial tissues, with several antioxidant, detoxification, and structural genes being highly expressed in both the bronchus and nose. Principle component analysis of previously defined smoking-induced genes from the bronchus suggested that smoking had a similar effect on gene expression in nasal epithelium. Gene set enrichment analysis demonstrated that this set of genes was also highly enriched among the genes most altered by smoking in both nasal and buccal epithelial samples. The expression of several detoxification genes was commonly altered by smoking in all three respiratory epithelial tissues, suggesting a common airway-wide response to tobacco exposure.Our findings support a relationship between gene expression in extra- and intrathoracic airway epithelial cells and extend the concept of a smoking-induced field of injury to epithelial cells that line the mouth and nose. This relationship could potentially be utilized to develop a non-invasive biomarker for tobacco exposure as well as a non-invasive screening or diagnostic tool providing information about individual susceptibility to smoking-induced lung diseases.

Project description:BackgroundThe production of gamma-amino butyric acid (GABA) is dependent on glutamate decarboxylases (GAD65 and GAD67), the enzymes that catalyze the decarboxylation of glutamate to GABA. Based on studies suggesting a role of the airway epithelial GABAergic system in asthma-related mucus overproduction, we hypothesized that cigarette smoking, another disorder associated with increased mucus production, may modulate GABAergic system-related gene expression levels in the airway epithelium.MethodsWe assessed expression of the GABAergic system in human airway epithelium obtained using bronchoscopy to sample the epithelium and microarrays to evaluate gene expression. RT-PCR was used to confirm gene expression of GABAergic system gene in large and small airway epithelium from heathy nonsmokers and healthy smokers. The differences in the GABAergic system gene was further confirmed by TaqMan, immunohistochemistry and Western analysis.ResultsThe data demonstrate there is a complete GABAergic system expressed in the large and small human airway epithelium, including glutamate decarboxylase, GABA receptors, transporters and catabolism enzymes. Interestingly, of the entire GABAergic system, smoking modified only the expression of GAD67, with marked up-regulation of GAD67 gene expression in both large (4.1-fold increase, p < 0.01) and small airway epithelium of healthy smokers (6.3-fold increase, p < 0.01). At the protein level, Western analysis confirmed the increased expression of GAD67 in airway epithelium of healthy smokers compared to healthy nonsmokers (p < 0.05). There was a significant positive correlation between GAD67 and MUC5AC gene expression in both large and small airway epithelium (p < 0.01), implying a link between GAD67 and mucin overproduction in association with smoking.ConclusionsIn the context that GAD67 is the rate limiting enzyme in GABA synthesis, the correlation of GAD67 gene expression with MUC5AC expressions suggests that the up-regulation of airway epithelium expression of GAD67 may contribute to the increase in mucus production observed in association with cigarette smoking.Trial registrationNCT00224198; NCT00224185.

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Smoking-induced upregulation of AKR1B10 expression in the airway epithelium of healthy individuals.

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Smoking-induced upregulation of AKR1B10 expression in the airway epithelium of healthy individuals.

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