Lung Tissue Of Nonsmokers Research Articles

CircANKRD11 Knockdown Protects HPMECs from Cigarette Smoke Extract-Induced Injury by Regulating miR-145-5p/BRD4 Axis.

BackgroundChronic obstructive pulmonary disease (COPD) is a major cause of death because of its high incidence and mortality, which is chiefly resulted from cigarette smoke exposure. A large number of studies show that circular RNA (circRNA) participates in regulating COPD process. This study aims to reveal the role of circRNA ankyrin repeat domain 11 (circANKRD11) in cigarette smoke extract (CSE)-induced cell apoptosis, inflammation, and oxidative stress.MethodsThe expression of circANKRD11, microRNA-145-5p (miR-145-5p) and bromodomain-containing 4 (BRD4) mRNA was detected by quantitative real-time polymerase chain reaction. The expression of apoptosis-related proteins and BRD4 protein was determined by Western blot. Cell apoptosis was detected by flow cytometry and Western blot. Cell inflammation was demonstrated by determining the levels of interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α) through enzyme-linked immunosorbent assay. Oxidative stress was investigated by the reactive oxygen species (ROS) and malondialdehyde (MDA) determination assays as well as superoxide dismutase (SOD) activity assay. The binding relationship between miR-145-5p and circANKRD11 or BRD4 was predicted by circinteractome or MicroT_CDS online database, and identified by dual-luciferase reporter, RNA immunoprecipitation or RNA pull-down assay.ResultsCircANKRD11 and BRD4 expression were increased, whereas miR-145-5p expression was decreased in the lung tissues of smokers with or without COPD and CSE-induced HPMECs compared with the lung tissues of non-smokers as well as untreated HPMECs, respectively. CircANKRD11 silencing ameliorated CSE-induced cell apoptosis, inflammation, and oxidative stress. CircANKRD11 acted as a sponge of miR-145-5p, and regulated CSE-induced cell injury via sponging miR-145-5p. Additionally, miR-145-5p mimics protected against CSE-induced cell injury through targeting BRD4.ConclusionCircANKRD11 absence protected HPMECs from CSE-induced injury by regulating BRD4 through associating with miR-145-5p, which demonstrated that circANKRD11 had the potential to act as a diagnosis biomarker for smoker-caused COPD.

Degradation of SARS-CoV-2 receptor ACE2 by the E3 ubiquitin ligase Skp2 in lung epithelial cells

An unexpected observation among the COVID-19 pandemic is that smokers constituted only 1.4%–18.5% of hospitalized adults, calling for an urgent investigation to determine the role of smoking in SARS-CoV-2 infection. Here, we show that cigarette smoke extract (CSE) and carcinogen benzo(a)pyrene (BaP) increase ACE2 mRNA but trigger ACE2 protein catabolism. BaP induces an aryl hydrocarbon receptor (AhR)-dependent upregulation of the ubiquitin E3 ligase Skp2 for ACE2 ubiquitination. ACE2 in lung tissues of non-smokers is higher than in smokers, consistent with the findings that tobacco carcinogens downregulate ACE2 in mice. Tobacco carcinogens inhibit SARS-CoV-2 spike protein pseudovirions infection of the cells. Given that tobacco smoke accounts for 8 million deaths including 2.1 million cancer deaths annually and Skp2 is an oncoprotein, tobacco use should not be recommended and cessation plan should be prepared for smokers in COVID-19 pandemic.Electronic Supplementary MaterialSupplementary material is available for this article at 10.1007/s11684-021-0837-6 and is accessible for authorized users.

Degradation of SARS-CoV-2 Receptor ACE2 by Tobacco Carcinogens

An unexpected observation among the COVID-19 pandemic is that smokers constituted only 1.4-18.5% of hospitalized adults, calling for an urgent investigation to determine the role of smoking in SARS-CoV-2 infection. Here, we show that cigarette smoke extract (CSE) and carcinogen benzo(a)pyrene (BaP) increase ACE2 mRNA but trigger ACE2 protein catabolism. BaP induces an aryl hydrocarbon receptor (AhR)-dependent upregulation of the ubiquitin E3 ligase Skp2 for ACE2 ubiquitination. ACE2 in lung tissues of non-smokers is higher than in smokers, consistent with the findings that tobacco carcinogens downregulate ACE2 in mice. Tobacco carcinogens inhibit SARS-CoV-2 Spike protein pseudovirions infection of the cells. These data indicate that recommendation of cessation of tobacco smoking remains valid because it is the carcinogens that are responsible for ACE2 degradation.

Aldehydes are the predominant forces inducing DNA damage and inhibiting DNA repair in tobacco smoke carcinogenesis

Tobacco smoke (TS) contains numerous cancer-causing agents, with polycyclic aromatic hydrocarbons (PAHs) and nitrosamines being most frequently cited as the major TS human cancer agents. Many lines of evidence seriously question this conclusion. To resolve this issue, we determined DNA adducts induced by the three major TS carcinogens: benzo(a)pyrene (BP), 4-(methylnitrosamine)-1-(3-pyridyl)-1-butanoe (NNK), and aldehydes in humans and mice. In mice, TS induces abundant aldehyde-induced γ-hydroxy-propano-deoxyguanosine (γ-OH-PdG) and α-methyl-γ-OH-PdG adducts in the lung and bladder, but not in the heart and liver. TS does not induce the BP- and NNK-DNA adducts in lung, heart, liver, and bladder. TS also reduces DNA repair activity and the abundance of repair proteins, XPC and OGG1/2, in lung tissues. These TS effects were greatly reduced by diet with polyphenols. We found that γ-OH-PdG and α-methyl-γ-OH-PdG are the major adducts formed in tobacco smokers' buccal cells as well as the normal lung tissues of tobacco-smoking lung cancer patients, but not in lung tissues of nonsmokers. However, the levels of BP- and NNK-DNA adducts are the same in lung tissues of smokers and nonsmokers. We found that while BP and NNK can induce BPDE-dG and O6-methyl-dG adducts in human lung and bladder epithelial cells, these inductions can be inhibited by acrolein. Acrolein also can reduce DNA repair activity and repair proteins. We propose a TS carcinogenesis paradigm. Aldehydes are major TS carcinogens exerting dominant effect: Aldehydes induce mutagenic PdG adducts, impair DNA repair functions, and inhibit many procarcinogens in TS from becoming DNA-damaging agents.

Microarray analysis of long non-coding RNAs in COPD lung tissue.

Long noncoding RNAs (lncRNAs) play an important role in the pathogenesis of many human diseases. In this study, we provide the description of genome-wide lncRNA expression in the lung tissue of non-smokers without Chronic obstructive pulmonary disease (COPD), of smokers without COPD and of smokers with COPD. RNA was extracted from human lung tissue and analysed using an Agilent Human lncRNA+mRNA Array v2.0 system. 39,253 distinct lncRNA transcripts were detected in the lung tissues of all subjects. In smokers without COPD 87 lncRNAs were significantly up-regulated and 244 down-regulated compared to non-smokers without COPD with RNA50010|UCSC-9199-1005 and RNA58351| CombinedLit_316_550, the most over- and under-regulated, respectively. In contrast, in COPD patients 120 lncRNAs were over-expressed and 43 under-expressed compared with smokers without COPD with RNA44121|UCSC-2000-3182 and RNA43510|UCSC-1260-3754 being the most over- and under-regulated, respectively. Gene Ontology (GO) and pathway analysis indicated that cigarette smoking was associated with activation of metabolic pathways, whereas COPD transcripts were associated with 'hematopoietic cell lineage', intermediary metabolism and immune system processes. We conclude that the altered expression of lncRNAs might play partial role in pathways implicated in COPD onset and progression such as intermediary metabolism and the immune response.

Endogenous and background DNA adducts by methylating and 2-hydroxyethylating agents

Detection of 7-alkylguanine DNA adducts is useful to assess human exposure to and the resulting DNA damage caused by simple alkylating agents. The background 7-methylguanine (7-MG) and 7-hydroxyethylguanine (7-HEG) adduct levels were determined in human and rat tissues, using thin-layer chromatography (TLC) combined with high pressure liquid chromatography (HPLC). In addition, these two adduct levels were also compared in various tissues between smokers and non-smokers. The results demonstrated that the background level of 7-alkylguanine adducts in WBC and lung tissues of non-smokers was 2.9 and 4.0 adducts/10 7 nucleotides, respectively. In smokers with lung cancers 7-MG adduct level in lung samples (6.3±1.9 adducts/10 7 nucleotides) and in bronchus samples (6.1±1.5 adducts/10 7 nucleotides) was significantly higher than that in WBC samples (3.3±0.9 adducts/10 7 nucleotides). 7-HEG adduct levels obtained from the same individuals were 0.8±0.3 in lung, 1.0±0.8 in bronchus and 0.6±0.2 adducts/10 7 nucleotides in WBC, respectively. Animal studies showed that background levels of 7-MG (2.1–2.5 adducts/10 7 nucleotides) in control rats were approximately 2–4-fold higher than 7-HEG levels (0.6–0.9 adducts/10 7 nucleotides). After a 3-day exposure to 300 ppm ethene, 7-HEG adducts accumulated to a similar extent in different tissues of rats, with the mean adduct level of 5.6–7.0 in liver, 7.4 in lymphocytes and 5.5 adducts/10 7 nucleotides in kidney.