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1.  Smoking-Related Gene Expression in Laser Capture Microdissected Human Lung 
Inter-individual differences in quantitative expression could underlie a propensity for lung cancer. To determine precise individual gene expression signatures on a lung compartment-specific basis, we investigated the expression of carcinogen metabolism genes encoding cytochromes P450 (CYP) 1B1, 2A13, glutathione S-transferase (GST) P1, and a tumor suppressor gene p16 in laser capture microdissected samples of human alveolar compartment (AC) and bronchial epithelial compartment (BEC) lung tissue from 62 smokers and non-smokers.
Experimental Design
Tobacco exposure was determined by plasma nicotine, cotinine, and smoking history. Precise mRNA expression was determined using our RNA-specific qRT-PCR strategy, and correlated with detailed demographic and clinical characteristics.
Several correlations of mRNA expression included: (a) CYP1B1 in AC (positively with plasma nicotine level, P = 0.008; plasma cotinine level, P = 0.001); (b) GSTP1 in AC (positively with plasma cotinine level, P = 0.003); (c) GSTP1 in BEC (negatively with smoke dose, P = 0.043; occupational risk, P = 0.019). CYP2A13 was rarely expressed in AC, and not expressed in BEC. p16 expression was not correlated with any measured factor. For each gene, subjects showed expression that was individually concordant between these compartments. No clear association of mRNA expression with lung cancer risk was observed in this pilot analysis.
The association between lung mRNA expression and tobacco exposure implies that gene-tobacco interaction is a measurable quantitative trait, albeit with wide inter-individual variation. Gene expression tends to be concordant for alveolar and bronchial compartments for these genes in an individual, controlling for proximate tobacco exposure.
PMCID: PMC4238890  PMID: 19996203
Lung carcinoma; gene expression; laser capture microdissection; lung epithelial cells; tobacco smoking
2.  A quantitative method to identify microRNAs targeting a messenger RNA using a 3′UTR RNA affinity technique 
Analytical biochemistry  2013;443(1):1-12.
The identification of specific microRNAs (miRNAs) that target a given messenger RNA (mRNA) is essential for studies in gene regulation, but the available bioinformatic software programs are often unreliable. We have developed a unique experimental miRNA affinity assay whereby a 3′UTR RNA is end-labeled with biotin, immobilized, and then used as a bait sequence for affinity pull-down of miRNAs. After washes and release, cloning and sequencing identify the miRNAs. Binding affinity is quantitated by quantitatvie polymerase chain reaction (qPCR), comparing released and original input concentrations. As an initial demonstration, the TCF8/ZEB1 mRNA affinity pull-down yielded miR-200 family member miRs in the majority of clones, and binding affinity was approximately 100%; virtually all copies of miR-200c bound the immobilized mRNA transcript. For validation in cells, miR-200c strongly inhibited expression of a TCF8 luciferase reporter, native TCF8 mRNA, and protein levels, which contrasted with other recovered miRNAs with lower binding affinities. For Smad4 mRNA, miR-150 (and others) displayed a binding affinity of 39% (or less) yet did not inhibit a Smad4 reporter, native Smad4 mRNA, or protein levels. These results were not predicted by available software. This work demonstrates this miRNA binding affinity assay to be a novel yet facile experimental means of identification of miRNAs targeting a given mRNA.
PMCID: PMC4112567  PMID: 23938772
miRNA; mRNA; miRNA:mRNA binding; Gene targeting; Gene modulation
3.  Genetic and epigenetic regulation of AHR gene expression in MCF-7 breast cancer cells: role of the proximal promoter GC-rich region 
Biochemical pharmacology  2012;84(5):722-735.
The aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor, contributes to carcinogenesis through its role in the regulation of cytochrome P450 1 (CYP1)-catalyzed metabolism of carcinogens. Here, we investigated genetic and epigenetic mechanisms that affect AhR expression. Analyses of the human AHR proximal promoter in MCF-7 human breast cancer cells using luciferase assays and electrophoretic mobility shift assays revealed multiple specificity protein (Sp) 1 binding sequences that are transcriptional activators in vitro. The regulation of AhR expression was evaluated in long-term estrogen exposed (LTEE) MCF-7 cells, which showed increased AhR expression, enhanced CYP1 inducibility, and increased capacity to form DNA adducts when exposed to the dietary carcinogen, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine. The increased AhR expression in LTEE cells was found not to result from increased mRNA stability, differential RNA processing, or decreased DNA methylation. Analysis of the AHR proximal promoter region using chromatin immunoprecipitation confirmed that enhanced expression of AhR in LTEE cells involves changes in histone modifications, notably decreased trimethylation of histone 3, lysine 27. Upon further examination of the GC-rich Sp1-binding region, we confirmed that it contains a polymorphic (GGGGC)n repeat. In a population of newborns from New York State, the allele frequency of (GGGGC)n was n = 4>5≫6, 2. Circular dichroism spectroscopy revealed the ability of sequences of this GC-rich region to form guanine-quadruplex structures in vitro. These studies revealed multiple levels at which AhR expression may be controlled, and offer additional insights into mechanisms regulating AhR expression that can ultimately impact carcinogenesis.
PMCID: PMC3965201  PMID: 22728919
aryl hydrocarbon receptor; long-term estrogen exposure; epigenetic; (GGGGC)n repeat polymorphism; guanine-quadruplex; 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine
4.  Lung cancer and its association with chronic obstructive pulmonary disease: update on nexus of epigenetics 
Purpose of review
Chronic obstructive pulmonary disease (COPD) and lung cancer are the leading causes of morbidity and mortality worldwide. The current research is focused on identifying the common and disparate events involved in epigenetic modifications that concurrently occur during the pathogenesis of COPD and lung cancer. The purpose of this review is to describe the current knowledge and understanding of epigenetic modifications in pathogenesis of COPD and lung cancer.
Recent findings
This review provides an update on advances of how epigenetic modifications are linked to COPD and lung cancer, and their commonalities and disparities. The key epigenetic modification enzymes (e.g. DNA methyltransferases – CpG methylation, histone acetylases/deacetylases and histone methyltransferases/demethylases) that are identified to play an important role in COPD and lung tumorigenesis and progression are described in this review.
Distinct DNA methyltransferases and histone modification enzymes are differentially involved in pathogenesis of lung cancer and COPD, although some of the modifications are common. Understanding the epigenetic modifications involved in pathogenesis of lung cancer or COPD with respect to common and disparate mechanisms will lead to targeting of epigenetic therapies against these disorders.
PMCID: PMC3730439  PMID: 21537190
chromatin; chronic obstructive pulmonary disease; epigenetics; histones; lung cancer; methylation
5.  Exhaled breath condensate appears to be an unsuitable specimen type for the detection of influenza viruses with nucleic acid-based methods 
Journal of virological methods  2009;163(1):144-146.
Exhaled breath condensate is an airway-derived specimen type that has shown significant promise in the diagnosis of asthma, cancer, and other disorders. The presence of human genomic DNA in this sample type has been proven, but there have been no reports on its utility for the detection of respiratory pathogens. The suitability of exhaled breath condensate for the detection of influenza virus was investigated, as an indication of its potential as a specimen type for respiratory pathogen discovery work. Matched exhaled condensates and nasopharyngeal swabs were collected from 18 adult volunteers. Eleven cases were positive for influenza A virus, and one was positive for influenza B virus. All swab samples tested positive in real-time amplification assays, but only one exhaled condensate, an influenza A positive sample with a very high viral load, tested positive in the real-time RT-PCR assay. Most of the positive nasopharyngeal swab samples inoculated for virus culture also tested positive, whereas influenza virus was not grown from any of the exhaled condensate specimens. It was concluded that influenza viruses are not readily detectable with culture or nucleic acid-based techniques in this sample type, and that exhaled breath condensate may not be suitable for respiratory pathogen investigations with molecular methods.
PMCID: PMC3730442  PMID: 19733195
Exhaled breath condensate; Influenza; Respiratory virus
6.  Haplotype-tagging single nucleotide polymorphisms in the GSTP1 gene promoter and susceptibility to lung cancer☆ 
Cancer detection and prevention  2009;32(0):403-415.
Glutathione S-transferase (GST) P1 is a major phase II xenobiotic-metabolizing enzyme in the human lung. Our laboratory had previously identified nine single nucleotide polymorphisms (SNPs) in the GSTP1 gene promoter, which were then grouped into three main haplotypes (Hap1, Hap2, and Hap3) based on statistical inference. Hap3 was found to display a high expression phenotype. The main objective of the current study was to test the association between GSTP1 promoter haplotypes with the risk of lung cancer after determining the promoter haplotypes experimentally through cloning and sequencing.
We conducted a case–control analysis of 150 subjects with lung cancer and 329 controls with no personal history of the disease. The three statistically inferred GSTP1 promoter haplotypes were confirmed experimentally through cloning and sequencing. Haplotype-tagging SNPs were selected and GSTP1 haplotypes were tested for genetic association to lung cancer using unconditional logistic regression after adjusting for confounders. Statistical interaction between GSTP1 promoter haplotypes with either cigarette smoking or dietary fruit and vegetable intake were tested using the likelihood ratio test.
We did not find protective effects of Hap3 against lung cancer, despite an adequately powered design for this main effect. Homozygous variants of tagSNPs –1738 T >A and –354 G > T, which tag Hap2, showed an increased (but statistically non-significant) risk of lung cancer among all subjects as well as among individuals with low fruit and vegetable intake, compared to homozygous wildtypes for these SNPs. We did not find significant interactions between Hap2 and dietary intake of fruits and vegetables.
Our results do not support significant main and modifying effects for GSTP1 promoter haplotypes on susceptibility to lung cancer in this population, but reinforce the protective effects of dietary intake of fruits and vegetables.
PMCID: PMC3730463  PMID: 19282111
Lung cancer; GSTP1; Promoter polymorphisms; Gene–environment interaction
7.  Dietary chemoprevention strategies for induction of phase II xenobiotic-metabolizing enzymes in lung carcinogenesis: A review 
Lung cancer is the leading cause of cancer mortality for men and women in the United States and is a growing worldwide problem. Protection against lung cancer is associated with higher dietary intake of fruits and vegetables, according to recent large epidemiologic studies. One strategy for lung cancer chemoprevention focuses on the use of agents to modulate the metabolism and disposition of tobacco, environmental and endogenous carcinogens through upregulation of detoxifying phase II enzymes. We summarize the substantial evidence that suggests that induction of phase II enzymes, particularly the glutathione S-transferases, plays a direct role in chemoprotection against lung carcinogenesis. The engagement of the Keap1–Nrf2 complex regulating the antioxidant response element (ARE) signaling pathway has been identified as a key molecular target of chemopreventive phase II inducers in several systems. Monitoring of phase II enzyme induction has led to identification of novel chemopreventive agents such as the isothiocyanate sulforaphane, and the 1,2-dithiole-3-thiones. However, no agents have yet demonstrated clear benefit in human cell systems, or in clinical trials. Alternative strategies include: (a) using intermediate cancer biomarkers for the endpoint in human trials; (b) high-throughput small molecule discovery approaches for induced expression of human phase II genes; and (c) integrative approaches that consider pharmacogenetics, along with pharmacokinetics and pharmacodynamics in target lung tissue. These approaches may lead to a more effective strategy of tailored chemoprevention efforts using compounds with proven human activity.
PMCID: PMC3730487  PMID: 19185948
Lung cancer; Phase II enzymes; Chemoprevention; Induction; Phytochemicals
8.  High-Throughput Library Screening Identifies Two Novel NQO1 Inducers in Human Lung Cells 
Many phytochemicals possess antioxidant and cancer-preventive properties, some putatively through antioxidant response element–mediated phase II metabolism, entailing mutagen/oxidant quenching. In our recent studies, however, most candidate phytochemical agents were not potent in inducing phase II genes in normal human lung cells. In this study, we applied a messenger RNA (mRNA)–specific gene expression–based high throughput in vitro screening approach to discover new, potent plant-derived phase II inducing chemopreventive agents. Primary normal human bronchial epithelial (NHBE) cells and immortalized human bronchial epithelial cells (HBECs) were exposed to 800 individual compounds in the MicroSource Natural Products Library. At a level achievable in humans by diet (1.0 μM), 2,3-dihydroxy-4-methoxy-4′-ethoxybenzophenone (DMEBP), triacetylresveratrol (TRES), ivermectin, sanguinarine sulfate, and daunorubicin induced reduced nicotinamide adenine dinucleotide phosphate:quinone oxidoreductase 1 (NQO1) mRNA and protein expression in NHBE cells. DMEBP and TRES were the most attractive agents as coupling potency and low toxicity for induction of NQO1 (mRNA level, ≥3- to 10.8-fold that of control; protein level, ≥ two- to fourfold that of control). Induction of glutathione S-transferase pi mRNA expression was modest, and none was apparent for glutathione S-transferase pi protein expression. Measurements of reactive oxygen species and glutathione/oxidized glutathione ratio showed an antioxidant effect for DMEBP, but no definite effect was found for TRES in NHBE cells. Exposure of NHBE cells to H2O2 induced nuclear translocation of nuclear factor erythroid 2–related factor 2, but this translocation was not significantly inhibited by TRES and DMEBP. These studies show that potency and low toxicity may align for two potential NQO1-inducing agents, DMEBP and TRES.
PMCID: PMC3326428  PMID: 22021338
GSTP1; NQO1; phytochemicals; high-throughput screening; gene expression
9.  The 3 prime paradigm of the miR-200 family and other microRNAs 
Epigenetics  2011;6(3):268-272.
The number of predicted human microRNAs in Sanger miRBase currently stands at over 1,000, with each of these in turn predicted to target numerous mRNAs. However, those microRNAs for which mRNA targets have been evaluated, verified and reported in the literature are still in the minority and the bulk of microRNA/mRNA interactions are yet to be confirmed. Confirmation of microRNA interaction with predicted mRNA targets represents a considerable undertaking, made more complex by potential synergistic effects of multiple microRNAs and the three possible outcomes (translational repression, degradation or a mixture of both). In addition, contrasting results obtained when either stably expressing or transiently transfecting members of the miR-200 family illustrate limitations in the verification methods currently in use. In this article we suggest that instead of allowing computational predictions to drive investigation, it would be desirable, when possible, to systematically evaluate microRNA targets using inducible, stable, ectopic expression. The advantage of stable lines ectopically expressing microRNA(s) is that they allow an analysis of changes to both the proteome and the transcriptome. This would allow verification of targets, improve the design of prediction algorithms and greatly increase our understanding of the outcome of microRNA/mRNA interaction.
PMCID: PMC3092674  PMID: 21242719
microRNA; target prediction; 3′UTR; mir-200 family; miR-200c
10.  Identification of Carcinogen DNA Adducts in Human Saliva by Linear Quadrupole Ion Trap/Multistage Tandem Mass Spectrometry 
Chemical research in toxicology  2010;23(7):1234-1244.
DNA adducts of carcinogens derived from tobacco smoke and cooked meat were identified, by liquid chromatography-electrospray ionization/multi-stage tandem mass spectrometry (LC-ESI/MS/MSn), in saliva samples from 37 human volunteers on unrestricted diets. The N-(deoxyguanosin-8-yl) (dG-C8) adducts of the heterocyclic aromatic amines 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP); 2-amino-9H-pyrido[2,3-b]indole (AαC); 2-amino-3,8-dimethylmidazo[4,5-f]quinoxaline (MeIQx); and the aromatic amine, 4-aminobiphenyl (4-ABP) were characterized and quantified, by LC-ESI/MS/MSn, employing consecutive reaction monitoring at the MS3 scan stage mode with a linear quadrupole ion trap (LIT) mass spectrometer (MS). DNA adducts of PhIP were found most frequently: dG-C8-PhIP was detected in saliva samples from 13 of 29 ever-smokers and in saliva samples from 2 of 8 never-smokers. dG-C8-AαC and dG-C8-MeIQx were identified solely in saliva samples of 3 current smokers, and dG-C8-4-ABP was detected in saliva from 2 current-smokers. The levels of these different adducts ranged from 1 to 9 adducts per 108 DNA bases. These findings demonstrate that PhIP is a significant DNA-damaging agent in humans. Saliva appears to be a promising biological fluid in which to assay DNA adducts of tobacco and dietary carcinogens, by selective LIT MS techniques.
PMCID: PMC2916027  PMID: 20443584
11.  Screening for DNA Adducts by Data-Dependent Constant Neutral Loss - Triple Stage (MS3) Mass Spectrometry with a Linear Quadrupole Ion Trap Mass Spectrometer 
Analytical chemistry  2009;81(2):809-819.
A 2-dimensional linear quadrupole ion trap mass spectrometer (LIT/MS) was employed to simultaneously screen for DNA adducts of environmental, dietary, and endogenous genotoxicants, by data-dependent constant neutral loss scanning followed by triple-stage mass spectrometry (CNL-MS3). The loss of the deoxyribose (dR) from the protonated DNA adducts ([M+H-116]+) in the MS/MS scan mode triggered the acquisition of MS3 product ion spectra of the aglycone adducts [BH2+]. Five DNA adducts of the tobacco carcinogen 4-aminobiphenyl (4-ABP) were detected in human hepatocytes treated with 4-ABP, and three DNA adducts of the cooked-meat carcinogen 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) were identified in the livers of rats exposed to MeIQx, by the CNL-MS3 scan mode. Buccal-cell DNA from tobacco smokers was screened for DNA adducts of various classes of carcinogens in tobacco smoke including 4-ABP, 2-amino-9H-pyrido[2,3-b]indole (AαC), and benzo[a]pyrene (BaP); the cooked-meat carcinogens MeIQx, AαC, and 2-amino-1-methyl-6-phenylmidazo[4,5-b]pyridine (PhIP); and the lipid peroxidation products acrolein (AC) and trans-4-hydroxynonenal (HNE). The CNL-MS3 scanning technique can be used to simultaneously screen for multiple DNA adducts derived from different classes of carcinogens, at levels of adduct modification approaching 1 adduct per 108 unmodified DNA bases, when 10 μg of DNA are employed for the assay.
PMCID: PMC2646368  PMID: 19086795
12.  Gene promoter methylation assayed in exhaled breath, with differences in smokers and lung cancer patients 
Respiratory Research  2009;10(1):86.
There is a need for new, noninvasive risk assessment tools for use in lung cancer population screening and prevention programs.
To investigate the technical feasibility of determining DNA methylation in exhaled breath condensate, we applied our previously-developed method for tag-adapted bisulfite genomic DNA sequencing (tBGS) for mapping of DNA methylation, and adapted it to exhaled breath condensate (EBC) from lung cancer cases and non-cancer controls. Promoter methylation patterns were analyzed in DAPK, RASSF1A and PAX5β promoters in EBC samples from 54 individuals, comprised of 37 controls [current- (n = 19), former- (n = 10), and never-smokers (n = 8)] and 17 lung cancer cases [current- (n = 5), former- (n = 11), and never-smokers (n = 1)].
We found: (1) Wide inter-individual variability in methylation density and spatial distribution for DAPK, PAX5β and RASSF1A. (2) Methylation patterns from paired exhaled breath condensate and mouth rinse specimens were completely divergent. (3) For smoking status, the methylation density of RASSF1A was statistically different (p = 0.0285); pair-wise comparisons showed that the former smokers had higher methylation density versus never smokers and current smokers (p = 0.019 and p = 0.031). For DAPK and PAX5β, there was no such significant smoking-related difference. Underlying lung disease did not impact on methylation density for this geneset. (4) In case-control comparisons, CpG at -63 of DAPK promoter and +52 of PAX5β promoter were significantly associated with lung cancer status (p = 0.0042 and 0.0093, respectively). After adjusting for multiple testing, both loci were of borderline significance (padj = 0.054 and 0.031). (5) The DAPK gene had a regional methylation pattern with two blocks (1)~-215~-113 and (2) -84 ~+26); while similar in block 1, there was a significant case-control difference in methylation density in block 2 (p = 0.045); (6)Tumor stage and histology did not impact on the methylation density among the cases. (7) The results of qMSP applied to EBC correlated with the corresponding tBGS sequencing map loci.
Our results show that DNA methylation in exhaled breath condensate is detectable and is likely of lung origin. Suggestive correlations with smoking and lung cancer case-control status depend on individual gene and CpG site examined.
PMCID: PMC2759916  PMID: 19781081

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