Project description:BackgroundUnlike normal cells, cancer cells frequently have multiple centrosomes that can cluster to form bipolar mitotic spindles and allow for successful cell division. Inhibiting centrosome clustering, therefore, holds therapeutic promise to promote cancer cell-specific cell death.MethodsWe used confocal microscopy, real-time PCR, siRNA knockdown, and western blot to analyze centrosome clustering and declustering using normal lung bronchial epithelial and nonsmall-cell lung cancer (NSCLC) cell lines. Also, we used Ingenuity Pathway Analysis software to identify novel pathways associated with centrosome clustering.ResultsIn this study, we found that exposure to cigarette smoke condensate induces centrosome amplification and clustering in human lung epithelial cells. We observed a similar increase in centrosome amplification and clustering in unexposed NSCLC cell lines which may suggest a common underlying mechanism for lung carcinogenesis. We identified a cyclin D2-mediated centrosome clustering pathway that involves a sonic hedgehog-forkhead box protein M1 axis which is critical for mitosis. We also observed that cyclin D2 knockdown induced multipolar mitotic spindles that could eventually lead to cell death.ConclusionsHere we report a novel role of cyclin D2 in the regulation of centrosome clustering, which could allow the identification of tumors sensitive to cyclin D2 inhibitors. Our data reveal a pathway that can be targeted to inhibit centrosome clustering by interfering with the expression of cyclin D2-associated genes.
Project description:Limited information is available regarding epigenomic events mediating initiation and progression of tobacco-induced lung cancers. In this study, we established an in vitro system to examine epigenomic effects of cigarette smoke in respiratory epithelia. Normal human small airway epithelial cells and cdk-4/hTERT-immortalized human bronchial epithelial cells (HBEC) were cultured in normal media with or without cigarette smoke condensate (CSC) for up to 9 months under potentially relevant exposure conditions. Western blot analysis showed that CSC mediated dose- and time-dependent diminution of H4K16Ac and H4K20Me3, while increasing relative levels of H3K27Me3; these histone alterations coincided with decreased DNA methyltransferase 1 (DNMT1) and increased DNMT3b expression. Pyrosequencing and quantitative RT-PCR experiments revealed time-dependent hypomethylation of D4Z4, NBL2, and LINE-1 repetitive DNA sequences; up-regulation of H19, IGF2, MAGE-A1, and MAGE-A3; activation of Wnt signaling; and hypermethylation of tumor suppressor genes such as RASSF1A and RAR-beta, which are frequently silenced in human lung cancers. Array-based DNA methylation profiling identified additional novel DNA methylation targets in soft-agar clones derived from CSC-exposed HBEC; a CSC gene expression signature was also identified in these cells. Progressive genomic hypomethylation and locoregional DNA hypermethylation induced by CSC coincided with a dramatic increase in soft-agar clonogenicity. Collectively, these data indicate that cigarette smoke induces 'cancer-associated' epigenomic alterations in cultured respiratory epithelia. This in vitro model may prove useful for delineating early epigenetic mechanisms regulating gene expression during pulmonary carcinogenesis.
Project description:In infants, smoke exposure is associated with more respiratory illnesses and decreased lung function. We hypothesized that perinatal lung is particularly susceptible to the damaging effects of cigarette smoke (CS) and that exposure to CS during this period may alter expression of immune response genes and adversely affect lung growth. To test this, we exposed neonatal mice to 14 days of CS. Immediately after exposure to CS, pulmonary gene expression profiling was performed on 2-week-old CS-exposed lung and age-matched control lung. Nitrotyrosine, TUNEL, MAC3, and phospho-SMAD-2 (p-SMAD2) staining was also performed. At 8 weeks of age, lung volume measurements were determined and mean linear intercept measurements were calculated. Pulmonary gene expression profiling revealed that CS exposure significantly inhibited type 1 and type 2 interferon pathway genes in neonatal lung, compared with age-matched control lung. Neonatal CS-exposed lung also had a significant increase in n-tyrosine, TUNEL, and p-SMAD2 staining when compared with adult CS-exposed lung and age-matched control lung. Lung volumes at 8 weeks of age were modestly but significantly decreased in mice exposed to CS in the neonatal period compared with age-matched controls, consistent with impaired lung growth. The results of this study indicate that exposure to CS during the neonatal period inhibits expression of genes involved in innate immunity and mildly impairs postnatal lung growth. These findings may in part explain the increased incidence of respiratory symptoms in infants and children exposed to CS.
Project description:BackgroundLung aging is characterized by a number of structural alterations including fibrosis, chronic inflammation and the alteration of inflammatory cell composition. Chronic exposure to cigarette smoke (CS) is known to induce similar alterations and may contribute to premature lung aging. Additionally, aging and CS exposure are associated with transcriptional alterations in the lung. The current work aims to explore the interaction between age- and CS- associated transcriptomic perturbations and develop a transcriptomic clock able to predict the biological age and the impact of external factors on lung aging.ResultsOur investigations revealed a substantial overlap between transcriptomic response to CS exposure and age-related transcriptomic alterations in the murine lung. Of particular interest is the strong upregulation of immunoglobulin genes with increased age and in response to CS exposure, indicating an important implication of B-cells in lung inflammation associated with aging and smoking. Furthermore, we used a machine learning approach based on Lasso regression to build a transcriptomic age model that can accurately predict chronological age in untreated mice and the deviations associated with certain exposures. Interestingly, CS-exposed-mice were predicted to be prematurely aged in contrast to mice exposed to fresh air or to heated tobacco products (HTPs). The accelerated aging rate associated with CS was reversed upon smoking cessation or switching to HTPs. Additionally, our model was able to predict premature aging associated with thoracic irradiation from an independent public dataset.ConclusionsAging and CS exposure share common transcriptional alteration patterns in the murine lung. The massive upregulation of B-cell restricted genes during these processes shed light on the contribution of cell composition and particularly immune cells to the measured transcriptomic signal. Through machine learning approach, we show that gene expression changes can be used to accurately monitor the biological age and the modulations associated with certain exposures. Our findings also suggest that the premature lung aging is reversible upon the reduction of harmful exposures.
Project description:Human alveolar epithelial cells were exposed to cigarette smoke extract (CSE) for 1, 3 and 5 weeks at 1%, 5% and 10%, and gene expression was evaluated by complete transcriptome microarrays. In this study we explored the effect of cigarette smoke on the gene expression profile.
Project description:Smoking is the main risk factor for many lung diseases including chronic obstructive pulmonary disease. Cigarette smoke (CS) contains carcinogenic and reactive oxygen species that favor DNA mutations and perturb the homeostasis and environment of cells. CS induces lung cell senescence resulting in a stable proliferation arrest and a senescence-associated secretory phenotype. It was recently reported that senescent cell accumulation promotes several lung diseases.
Project description:The pharmacological effects of tobacco products are primarily mediated by nicotine; however, research suggests that several non-nicotine tobacco constituents may alter the reinforcing effects of nicotine. This study evaluated the reinforcing effects of aqueous solutions of smoke/aerosol condensate from cigarettes, little cigars, electronic cigarettes (e-cigarettes), and waterpipe tobacco in a self-administration procedure to determine if abuse liability of these tobacco products differed. Adult male Sprague-Dawley rats (n = 64 total) were trained to self-administer intravenous nicotine (30 μg/kg/infusion) on a fixed ratio 5 schedule of reinforcement. Following nicotine dose-effect assessment (1, 7.5, 15, and 30 μg/kg/infusion), rats were given access to smoke/aerosol condensate derived from their assigned tobacco product. Rats responded for smoke/aerosol condensate containing 1, 7.5, 15, and 30 μg/kg/infusion nicotine, with the ratio of nicotine:non-nicotine constituents held constant across doses for each tobacco product. Responding for nicotine or smoke/aerosol condensate was also assessed on a progressive ratio schedule of reinforcement. Cigarette, little cigar, and e-cigarette smoke/aerosol condensates shifted the nicotine dose-effect curve leftward, whereas waterpipe tobacco smoke condensate shifted the dose-effect curve rightward. Smoke/aerosol condensate from all tobacco products produced similar levels of responding compared to nicotine alone during the progressive ratio phase. Results suggest that non-nicotine constituents in cigarettes, little cigars, and e-cigarettes differentially enhance nicotine's reinforcing potency. In contrast, waterpipe tobacco blunted nicotine's reinforcing potency, suggesting that it may contain unique constituents that dampen nicotine's reinforcing effects.
Project description:Wnt7a is known to be a tumor suppressor that is lost in NSCLC, but no mechanism of loss has been established. Methylation of promoter regions has been established as a common mechanism of loss of tumor suppressor expression in NSCLC. We previously demonstrated that loss of Wnt7a in non-transformed lung epithelial cell lines led to increased cell growth, altered 3-D culture growth, and increased migration. The Wnt7a promoter has a higher percentage of methylation in NSCLC tumor tissue compared to matched normal lung tissue and methylation of the promoter region leads to decreased activity. We treated H157 and H1299 NSCLC cell lines with 5-Aza-2'-deoxycytidine and detected loss of Wnt7a promoter methylation, increased Wnt7a expression, and increased activity of the Wnt7a lung signaling pathway. When DNMT1 expression was knocked down by shRNA, expression of Wnt7a increased and methylation decreased. Together these data suggest that in NSCLC, Wnt7a is lost by methylation in a subset of tumors and that this methylation is maintained by DNMT1. Restoration of Wnt7a expression through demethylation could be an important therapeutic approach in the treatment of NSCLC.
Project description:Smoking is known to be an added risk factor for tuberculosis (TB), with nearly a quarter of the TB cases attributed to cigarette smokers in the 22 countries with the highest TB burden. Many studies have indicated a link between risk of active TB and cigarette smoke. Smoking is also known to significantly decrease TB cure and treatment completion rate and increase mortality rates. Cigarette smoke contains thousands of volatile compounds including carcinogens, toxins, reactive solids, and oxidants in both particulate and gaseous phase. Yet, to date, limited studies have analyzed the impact of cigarette smoke components on Mycobacterium tuberculosis (Mtb), the causative agent of TB. Here we report the impact of cigarette smoke condensate (CSC) on survival, mutation frequency, and gene expression of Mtb in vitro. We show that exposure of virulent Mtb to cigarette smoke increases the mutation frequency of the pathogen and strongly induces the expression of the regulon controlled by SigH-a global transcriptional regulator of oxidative stress. SigH has previously been shown to be required for Mtb to respond to oxidative stress, survival, and granuloma formation in vivo. A high-SigH expression phenotype is known to be associated with greater virulence of Mtb. In patients with pulmonary TB who smoke, these changes may therefore play an important, yet unexplored, role in the treatment efficacy by potentially enhancing the virulence of tubercle bacilli.
Project description:Mycbacterium tuberculosis was exposed to cigarette smoke condensate (CSC) in 7H9 dextrose culture media. The transcriptional response to cigarette smoke condensate was compared to that of exposure to the CSC diluent, DMSO..