Component Of Tobacco Research Articles

Acute Tolerance to the Discriminative Stimulus Effects of Nicotine in Monkeys

Tolerance to the effects of nicotine, a major psychoactive component of tobacco, contributes to escalation in the frequency and quantity of tobacco use. However, mechanisms of tolerance to the effects of nicotine are not well understood. Here, drug discrimination was used to examine the rapid decrease in sensitivity to nicotine (i.e., acute tolerance), including its underlying receptor pharmacology and its relationship to nicotine pharmacokinetics. Rhesus monkeys (n=6) discriminated 0.032 mg/kg of nicotine base administered i.v. under an FR5 schedule of stimulus‐shock termination. Nicotine dose‐dependently increased drug‐lever responding; the ED50 value (95% confidence limits) of nicotine to produce discriminative stimulus effects was 0.012 (0.0077–0.020) mg/kg. The β2‐selective nicotinic acetylcholine receptor (nAChR) antagonist dihydro‐β‐erythroidine produced a 4.8‐fold rightward shift in the nicotine dose‐response function. Methyllycaconitine, an α7‐selective nAChR antagonist, up to 10 mg/kg did not antagonize the nicotine discriminative stimulus. The duration of the nicotine discriminative stimulus was less than 30 min; however, concentrations of nicotine measured in saliva were maximal (45–65 ng/ml) 10–30 min post‐injection. Pretreatment with nicotine (0.032 mg/kg i.v.) 30 min before re‐determination of sensitivity to the effects of nicotine resulted in a 3‐fold rightward shift in the dose‐response function. Firstly, these data suggest that the i.v. nicotine discriminative stimulus is mediated by β2‐containing, not α7‐containing, nAChRs. Secondly, decreased sensitivity to the discriminative stimulus effects of nicotine when preceded by an additional dose of nicotine 30 min earlier provides evidence of acute tolerance. That the peak concentrations of nicotine in saliva persist beyond the offset of its discriminative stimulus effects is also consistent with acute pharmacodynamic tolerance. Collectively, these results demonstrate that tolerance to the discriminative stimulus effects of nicotine can be produced by acute exposure to nicotine and suggest that the mechanism underlying acute tolerance may be related to rapid desensitization of β2‐containing nAChRs.Support or Funding InformationSupported by United States Public Health Service Grant DA 25267.

Effect of two-stage dehydration on retention of characteristic flavor components of flue-cured tobacco in rotary dryer

ABSTRACTTwo-stage dehydration method of flue-cured tobacco in rotary dryer was experimentally evaluated and compared to the single-stage dehydration process. The characteristic flavor components in dried cut tobacco, including major Maillard reaction compounds and carotenoid degradation products, as well as drying rate were analyzed for different two-stage dehydration operations. The results showed that both the pre-drying temperature and intermediate moisture content had a significant effect on the overall drying rate of cut tobacco during two-stage drying. On the other hand, the retention of characteristic flavor components in tobacco, especially Maillard reaction compounds retention, was influenced significantly by the final drying temperature as well as intermediate moisture content. The 10°C increase in the final drying temperature from 100 to 110°C reduced the retentions of Maillard reaction compounds and carotenoid degradation products by 14.5 and 9.4%, respectively. Change of intermediate moisture contents from 19 to 15% reduced the Maillard reaction compounds retention by 14.7%. Given the consideration of characteristic flavor components’ retention and drying process efficiency, two-stage dehydration of cut tobacco in rotary dryer could reach a better performance as compared with the single-stage dehydration. The cylinder-wall temperature combination of 140/100°C with the 17% intermediate moisture content could be used as the optimal two-stage condition for the investigated flue-cured tobacco.

Nicotine-induced resistance of non-small cell lung cancer to treatment--possible mechanisms.

Cigarette smoking is the leading risk factor of lung cancer. Data from several clinical studies suggest that continuation of smoking during therapy of tobacco-related cancers is associated with lower response rates to chemotherapy and/or radiotherapy, and even with decreased survival. Although nicotine--an addictive component of tobacco--is not a carcinogen, it may influence cancer development and progression or effectiveness of anti-cancer therapy. Several in vitro and in vivo trials have evaluated the influence of nicotine on lung cancer cells. The best known mechanisms by which nicotine impacts cancer biology involve suppression of apoptosis induced by certain drugs or radiation, promotion of proliferation, angiogenesis, invasion and migration of cancer cells. This effect is mainly mediated by membranous nicotinic acetylcholine receptors whose stimulation leads to sustained activation of such intracellular pathways as PI3K/Akt/mTOR, RAS/RAF/MEK/ERK and JAK/STAT, induction of NF-κB activity, enhanced transcription of mitogenic promoters, inhibition of the mitochondrial death pathway or stimulation of pro-angiogenic factors. We herein summarize the mechanisms underlying nicotine's influence on biology of lung cancer cells and the effectiveness of anti-cancer therapy.

Rapid determination of the volatile components in tobacco by ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction with gas chromatography-mass spectrometry.

An ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction was first employed to determine the volatile components in tobacco samples. The method combined the advantages of ultrasound, microwave, and headspace solid-phase microextraction. The extraction, separation, and enrichment were performed in a single step, which could greatly simplify the operation and reduce the whole pretreatment time. In the developed method, several experimental parameters, such as fiber type, ultrasound power, and irradiation time, were optimized to improve sampling efficiency. Under the optimal conditions, there were 37, 36, 34, and 36 components identified in tobacco from Guizhou, Hunan, Yunnan, and Zimbabwe, respectively, including esters, heterocycles, alkanes, ketones, terpenoids, acids, phenols, and alcohols. The compound types were roughly the same while the contents were varied from different origins due to the disparity of their growing conditions, such as soil, water, and climate. In addition, the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method was compared with the microwave-assisted extraction coupled to headspace solid-phase microextraction and headspace solid-phase microextraction methods. More types of volatile components were obtained by using the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction method, moreover, the contents were high. The results indicated that the ultrasound-microwave synergistic extraction coupled to headspace solid-phase microextraction technique was a simple, time-saving and highly efficient approach, which was especially suitable for analysis of the volatile components in tobacco.

Nicotine Inhibits Cisplatin-Induced Apoptosis via Regulating α5-nAChR/AKT Signaling in Human Gastric Cancer Cells.

Gastric cancer incidence demonstrates a strong etiologic association with smoking. Nicotine, the major component in tobacco, is a survival agonist that inhibits apoptosis induced by certain chemotherapeutic agents, but the precise mechanisms involved remain largely unknown. Recently studies have indicated that α5-nicotinic acetylcholine receptor (α5-nAChR) is highly associated with lung cancer risk and nicotine dependence. Nevertheless, no information has been available about whether nicotine also affects proliferation of human gastric cancer cells through regulation of α5-nAChR. To evaluate the hypothesis that α5-nAChR may play a role in gastric cancer, we investigated its expression in gastric cancer tissues and cell lines. The expression of α5-nAChR increased in gastric cancer tissue compared with para-carcinoma tissues. In view of the results, we proceeded to investigate whether nicotine inhibits cisplatin-induced apoptosis via regulating α5-nAChR in gastric cancer cell. The results showed that nicotine significantly promoted cell proliferation in a dose and time-dependent manner through α5-nAChR activation in human gastric cells. Furthermore, nicotine inhibited apoptosis induced by cisplatin. Silence of α5-nAChR ablated the protective effects of nicotine. However, when co-administrating LY294002, an inhibitor of PI3K/AKT pathway, an increased apoptosis was observed. This effect correlated with the induction of Bcl-2, Bax, Survivin and Caspase-3 by nicotine in gastric cell lines. These results suggest that exposure to nicotine might negatively impact the apoptotic potential of chemotherapeutic drugs and that α5-nAChR/AKT signaling plays a key role in the anti-apoptotic activity of nicotine induced by cisplatin.

Blockade of Nicotine and Cannabinoid Reinforcement and Relapse by a Cannabinoid CB1-Receptor Neutral Antagonist AM4113 and Inverse Agonist Rimonabant in Squirrel Monkeys.

Nicotine, the main psychoactive component of tobacco, and (-)-Δ(9)-tetrahydrocannabinol (THC), the main psychoactive ingredient in cannabis, play major roles in tobacco and marijuana dependence as reinforcers of drug-seeking and drug-taking behavior. Drugs that act as inverse agonists of cannabinoid CB1 receptors in the brain can attenuate the rewarding and abuse-related effects of nicotine and THC, but their clinical use is hindered by potentially serious side effects. The recently developed CB1-receptor neutral antagonists may provide an alternative therapeutic approach to nicotine and cannabinoid dependence. Here we compare attenuation of nicotine and THC reinforcement and reinstatement in squirrel monkeys by the CB1-receptor inverse agonist rimonabant and by the recently developed CB1-receptor neutral antagonist AM4113. Both rimonabant and AM4113 reduced two effects of nicotine and THC that play major roles in tobacco and marijuana dependence: (1) maintenance of high rates of drug-taking behavior, and (2) priming- or cue-induced reinstatement of drug-seeking behavior in abstinent subjects (models of relapse). In contrast, neither rimonabant nor AM4113 modified cocaine-reinforced or food-reinforced operant behavior under similar experimental conditions. However, both rimonabant and AM4113 reduced cue-induced reinstatement in monkeys trained to self-administer cocaine, suggesting the involvement of a common cannabinoid-mediated mechanism in the cue-induced reinstatement for different drugs of abuse. These findings point to CB1-receptor neutral antagonists as a new class of medications for treatment of both tobacco dependence and cannabis dependence.

Enhancement of the genotoxicity of benzo[a]pyrene by arecoline through suppression of DNA repair in HEp-2 cells

The International Agency for Research on Cancer lists the principal component of betel quid (BQ), the areca nut, and that of cigarette smoke, benzo[a]pyrene (BaP), as Group 1 carcinogens. Epidemiological studies have shown that coexposure of BQ and cigarette smoke markedly increases the risk of cancer. We previously demonstrated that arecoline, the most abundant alkaloid in the areca nut, inhibits nucleotide excision repair through the repression of p53 activity. To investigate the combined potency of arecoline and BaP in carcinogenesis, we treated human epithelial HEp-2 cells with subcytotoxic doses of arecoline and BaP, alone or in combination, and examined the effects on DNA damage and repair. When exposed for 24h, BaP enhanced DNA repair and p53 transactivation activity. However, these enhancements were suppressed through concurrent treatment of the cells with arecoline. Using a Comet assay, we found that extended exposure to arecoline and BaP caused moderate-to-severe DNA damage in 60% of the cells. Expression of the XPD helicase was transcriptionally suppressed by 1week of treatment with BaP. Our studies have revealed potential targets in the DNA repair pathway that are affected by BQ and tobacco components, as well as the effect of these components on carcinogenesis.

Common and Distinct Interactions of Chemical Inhibitors with Cytochrome P450 CYP1A2, CYP2A6 and CYP2B6 Enzymes

Tobacco smoking is a leading cause of preventable disease and death globally. Nicotine is the main addictive component in tobacco. Nicotine is eliminated from the body by biotransformation in the liver to inactive metabolites. This reaction is catalyzed by the cytochrome P450 2A6 (CYP2A6) enzyme. Administering chemical inhibitors of CYP2A6 has been shown to slow down the elimination of nicotine with consequent reduction in number of cigarettes smoked. We have systematically developed small molecule CYP2A6 inhibitors with good balance between potency and CYP selectivity. During this process we have noticed that many potent CYP2A6 inhibitors also inhibit other human liver CYP forms, most notably CYP1A2 and CYP2B6. This study aimed at defining common and distinct features of ligand binding to CYP1A2, CYP2A6 and CYP2B6 active sites. We used our previous chemical inhibitor databases to construct improved 3-dimensional quantitative structureactivity relationship (3D-QSAR) models for CYP1A2, CYP2A6 and CYP2B6. Combined 3D-QSAR and docking procedures yielded precise information about the common and distinct interactions of inhibitors and the enzyme active sites. Positioning of hydrogen bond donor/acceptor atoms and the shape and volume of the compound defined the potency and specificity of inhibition. A novel potent and selective CYP1A2 inhibitor was found. This in silico approach will provide a means for very rapid and high throughput prediction of cross-inhibition of these three CYP enzymes.

Antiplatelet Agents: All for One, One for All… Is it Still True?

Submit Manuscript | http://medcraveonline.com J Cardiol Curr Res 2016, 5(2): 00155 to stick to the inner lining of blood vessels and cause a blockage that disrupts blood flow. However, when there is a buildup of fatty deposits (atherosclerosis) within blood vessels, the lining of the vessels (the endothelium) is less resistant to blood clotting [2]. A variety of stimuli, including high blood pressure, high blood sugar, and poisonous chemicals, like tobacco components may make atherosclerotic fat deposits (plaques) unstable. This is particularly true when plaques are rich in fat (cholesterol) and white blood cells (inflammatory cells). An unstable plaque may crack or rupture and expose its contents to flowing blood. In its own defense, the body attempts to heal this injury by forming a blood clot over the damaged area [3].

Cognitive control deficits during mecamylamine-precipitated withdrawal in mice: Possible links to frontostriatal BDNF imbalance

Nicotine is a major psychoactive and addictive component of tobacco. Although cessation of tobacco use produces various somatic and affective symptoms, withdrawal-related cognitive deficits are considered to be a critical symptom that predict relapse. Therefore, delineating the cognitive mechanisms of nicotine withdrawal may likely provide gainful insights into the neurobiology of nicotine addiction. The present study was designed to examine the effects of nicotine withdrawal induced by mecamylamine, a non-specific nicotinic receptor (nAChR) antagonist, on cognitive control processes in mice using an operant strategy switching task. Brain-derived neurotrophic factor (BDNF) modulates synaptic transmission in frontostriatal circuits, and these circuits are critical for executive functions. Thus, we examined the effects of mecamylamine-precipitated nicotine withdrawal on prefrontal and striatal BDNF protein expression. Mice undergoing precipitated nicotine withdrawal required more trials to attain strategy switching criterion as compared to the controls. Error analysis indicated that impaired performance in these animals was mostly related to their inability to execute the new strategy. The striatal/prefrontal BDNF ratios robustly increased following precipitated nicotine withdrawal. Moreover, higher BDNF ratios were associated with longer task acquisition. Collectively, our findings illustrate that mecamylamine-induced nicotine withdrawal disrupts cognitive control processes and that these changes are possibly linked to perturbations in frontostriatal BDNF signaling.

Neuroscience of nicotine for addiction medicine: novel targets for smoking cessation medications.

Morbidity and mortality associated with tobacco smoking constitutes a significant burden on healthcare budgets all over the world. Therefore, promoting smoking cessation is an important goal of health professionals and policy makers throughout the world. Nicotine is a major psychoactive component in tobacco that is largely responsible for the widespread addiction to tobacco. A majority of the currently available FDA-approved smoking cessation medications act via neuronal nicotinic receptors. These medications are effective in approximately half of all the smokers, who want to quit and relapse among abstinent smokers continues to be high. In addition to relapse among abstinent smokers, unpleasant effects associated with nicotine withdrawal are a major motivational factor in continued tobacco smoking. Over the last two decades, animal studies have helped in identifying several neural substrates that are involved in nicotine-dependent behaviors including those associated with nicotine withdrawal and relapse to tobacco smoking. In this review, first the role of specific brain regions/circuits that are involved in nicotine dependence will be discussed. Next, the review will describe the role of specific nicotinic receptor subunits in nicotine dependence. Finally, the review will discuss the role of classical neurotransmitters (dopamine, serotonin, noradrenaline, glutamate, and γ-aminobutyric acid) as well as endogenous opioid and endocannabinoid signaling in nicotine dependence. The nicotinic and nonnicotinic neural substrates involved in nicotine-dependent behaviors can serve as possible targets for future smoking cessation medications.

The Development of DNA Based Methods for the Reliable and Efficient Identification of Nicotiana tabacum in Tobacco and Its Derived Products.

Reliable methods are needed to detect the presence of tobacco components in tobacco products to effectively control smuggling and classify tariff and excise in tobacco industry to control illegal tobacco trade. In this study, two sensitive and specific DNA based methods, one quantitative real-time PCR (qPCR) assay and the other loop-mediated isothermal amplification (LAMP) assay, were developed for the reliable and efficient detection of the presence of tobacco (Nicotiana tabacum) in various tobacco samples and commodities. Both assays targeted the same sequence of the uridine 5′-monophosphate synthase (UMPS), and their specificities and sensitivities were determined with various plant materials. Both qPCR and LAMP methods were reliable and accurate in the rapid detection of tobacco components in various practical samples, including customs samples, reconstituted tobacco samples, and locally purchased cigarettes, showing high potential for their application in tobacco identification, particularly in the special cases where the morphology or chemical compositions of tobacco have been disrupted. Therefore, combining both methods would facilitate not only the detection of tobacco smuggling control, but also the detection of tariff classification and of excise.

To quit or not: Vulnerability of women to smoking tobacco

ABSTRACTTobacco smoking is currently on the rise among women, and can pose a greater health risk. In order to understand the nature of the increase in smoking prevalence among women, we focused on the vulnerability of women to smoking behaviors—smoking cessation or tobacco addiction—and performed a systematic review of the socioeconomic and intrinsic factors as well as tobacco ingredients that affect women's susceptibility to smoking tobacco. We observed that nicotine and other tobacco components including cocoa-relatives, licorice products, and menthol aggravate tobacco addiction in women rather than in men. Various genetic and epigenetic alterations in dopamine pathway and the pharmaco-kinetics and -dynamic factors of nicotine also showed potential evidences for high susceptibility to tobacco addiction in women. Therefore, we suggest systemic approaches to prevent tobacco smoking–related health risks, considering gene–environment–gender interaction.

A Comprehensive Lifestyle Peer Group–Based Intervention on Cardiovascular Risk Factors: The Randomized Controlled Fifty-Fifty Program

BackgroundCardiovascular diseases stem from modifiable risk factors. Peer support is a proven strategy for many chronic illnesses. Randomized trials assessing the efficacy of this strategy for global cardiovascular risk factor modification are lacking. ObjectivesThis study assessed the hypothesis that a peer group strategy would help improve healthy behaviors in individuals with cardiovascular risk factors. MethodsA total of 543 adults 25 to 50 years of age with at least 1 risk factor were recruited; risk factors included hypertension (20%), overweight (82%), smoking (31%), and physical inactivity (81%). Subjects were randomized 1:1 to a peer group–based intervention group (IG) or a self-management control group (CG) for 12 months. Peer-elected leaders moderated monthly meetings involving role-play, brainstorming, and activities to address emotions, diet, and exercise. The primary outcome was mean change in a composite score related to blood pressure, exercise, weight, alimentation, and tobacco (Fuster-BEWAT score, 0 to 15). Multilevel models with municipality as a cluster variable were applied to assess differences between groups. ResultsParticipants’ mean age was 42 ± 6 years, 71% were female, and they had a mean baseline Fuster-BEWAT score of 8.42 ± 2.35. After 1 year, the mean scores were significantly higher in the IG (n = 277) than in the CG (n = 266) (IG mean score: 8.84; 95% confidence interval (CI): 8.37 to 9.32; CG mean score: 8.17; 95% CI: 7.55 to 8.79; p = 0.02). The increase in the overall score was significantly larger in the IG compared with the CG (difference: 0.75; 95% CI: 0.32 to 1.18; p = 0.02). The mean improvement in the individual components was uniformly greater in the IG, with a significant difference for the tobacco component. ConclusionsThe peer group intervention had beneficial effects on cardiovascular risk factors, with significant improvements in the overall score and specifically on tobacco cessation. A follow-up assessment will be performed 1 year after the final assessment reported here to determine long-term sustainability of the improvements associated with peer group intervention. (Peer-Group-Based Intervention Program [Fifty-Fifty]; NCT02367963)

Nicotine intake and problem solving strategies are modified during a cognitively demanding water maze task in rats

BackgroundNicotine is the major addictive component in tobacco, and despite well-established adverse health effects of tobacco addiction, some smokers have difficulty quitting. The acute cognitive enhancement and/or the amelioration of the cognitive disruption during withdrawal that some smokers experience after smoking are among important factors that hinder quit attempts. The animal model presented in the current study is comparable to the human smoking condition although nicotine intake routes are different. Rats were exposed to a free choice of oral nicotine starting at adolescence, and given a water maze (WM) task as adults. This design allowed us to see if rats alter their nicotine intake during the WM task and if nicotine preference and intake modify abilities and strategies rats use for problem solving. MethodsMale and female rats were exposed to a free choice of oral nicotine/water for 24weeks, starting at five weeks of age. After this period, they were selected based on their nicotine intake and, together with control animals that received only water, were subjected to a place-learning task in the WM. Free-choice nicotine exposure continued during WM testing. Following acquisition, the probe trial presented the rats with a choice between using two different strategies for problem solving. ResultsNicotine supported acquisition and rats increased their nicotine intake during WM testing; this effect was more pronounced in male rats with minimum nicotine preference and intake. Furthermore, nicotine modified the “female type” strategy in solving the place-learning task and nicotine treated female rats, unlike control females, behaved like males. ConclusionsThe increase in nicotine intake during mental engagement, and the sexually dimorphic effect of nicotine on problem solving strategies that we have observed in rats, may suggest that implementing sex-specific smoking cessation approaches, especially under stressful and cognitively demanding conditions, may be useful in helping smokers quit.

Abstract B22: The role of e-cigarette exposure on pulmonary epithelial cell transformation

Abstract Despite a strong correlation between cigarette smoking and the onset of lung cancer, the prevalence of smoking still remains high. The electronic cigarette (ECIG) is designed to deliver nicotine without combusting tobacco. Since nicotine is widely considered the addictive component in tobacco with limited ability to initiate cancer, ECIGs have been advertised to be a safer alternative to tobacco cigarettes. However, the potential health risks and carcinogenicity of ECIGs have not previously been evaluated. In this study, we assess the impact of ECIG exposure on the carcinogenic potential of immortalized human bronchial epithelial cells on a background of silenced p53 and activated KRAS (H3mut-P53/KRAS). This model is utilized because p53 and KRAS mutations are often observed in the airway of current and former smokers at risk for lung cancer. In anchorage independent growth assays, the in vitro correlate of malignant transformation, we found enhanced colony growth in the HBEC-P53/KRAS cells following a 12-day treatment with high concentrations of ECIG-conditioned media compared to the untreated and low concentration treatment groups. We next assessed the effect of ECIG and exposure on cell invasion using three-dimensional air-liquid interface (ALI) models. HBEC-P53/KRAS cells exhibited invasion-associated morphological changes following a 12-day treatment with the high conditioned media, including increased proliferation, diminished cell-cell cohesion and the appearance of cells percolating out of and breaching the modified basement membrane. Finally, to identify the biological impact of in vitro ECIG exposure in HBECs, we profiled the gene expression of P53/KRAS cells following a 96-hour exposure to ECIG- or tobacco cigarette (TCIG)-conditioned media. We found that epithelial cells exposed to clinically relevant concentrations of ECIG vapor-conditioned media have a gene expression pattern similar to those exposed to TCIG smoke-conditioned media and whole cigarette smoke. Rank-rank hyper-geometric overlap (RRHO) analysis indicated that differential expression - based ranked genes in TCIG and ECIG exposed groups were consistently overlapped at significant levels. There were 263 differentially expressed genes in the cells treated with high ECIG media versus untreated control. Annotations of the identified genes by the Molecular Signature database revealed several enriched biological pathways involved in malignant transformation and epithelial-mesenchymal transition (EMT). We have compared the resulting list of genes to publicly available microarray datasets and identified several transformation-related gene candidates. We are in the process of evaluating their contribution to ECIG-induced dissemination and carcinogenesis in vitro and in vivo. These studies will determine the impact of ECIG exposure on lung carcinogenicity and provide needed scientific guidance to the FDA regarding the physiologic effects of ECIGs. These studies were supported by funding from the following: NIH/NCI #U01CA152751 (SMD, TCW), NCI #U01CA152751-S1 (SMD, TCW, SJP), NCI #U01CA152751-AS (SMD, KK), NCI #T32-CA009120-36 (SMD, SJP, PCP), NIH/NHLBI #T32HL072752 (SMD, EL), University of California Tobacco-Related Disease Research Program (TRDRP) #18FT-0060 (TCW), TRDRP #20KT-0055 (TCW), Prevent Cancer Foundation (SJP), Lung Cancer SPORE (P50CA70907, JDM, JEL) Citation Format: Stacy J. Park, Tonya C. Walser, Linh M. Tran, Catalina Perdomo, Teresa Wang, Long-Sheng Hong, Paul C. Pagano, Elvira L. Liclican, Jill E. Larsen, Kostyantyn Krysan, Michael C. Fishbein, John D. Minna, Marc E. Lenburg, Spira Avrum, Steven Dubinett. The role of e-cigarette exposure on pulmonary epithelial cell transformation. [abstract]. In: Proceedings of the Thirteenth Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2014 Sep 27-Oct 1; New Orleans, LA. Philadelphia (PA): AACR; Can Prev Res 2015;8(10 Suppl): Abstract nr B22.

α5-nAChR modulates nicotine-induced cell migration and invasion in A549 lung cancer cells

Cigarette smoking is the most important risk factor in the development of human lung cancer. Nicotine, the major component in tobacco, not only contributes to carcinogenesis but also promotes tumor metastasis. By binding to nicotinic acetylcholine receptors (nAChRs), nicotine induces the proliferation and migration of non-small cell lung cancer. Recently studies have indicated that α5-nAChR is highly associated with lung cancer risk and nicotine dependence. Nevertheless, it is unclear whether nicotine promotes the migration and invasion through activation of α5-nAChR in lung cancer. In the present study, A549 cell was exposed to 1μN nicotine for 8, 24 or 48h. Wound-healing assay and transwell assay were used to evaluate the capability of A549 cell migration and cell invasion, respectively. Silencing of α5-nAChR was done by siRNA. Western blotting and PCR were used to detect α5-nAChR expression. Nicotine can induce activation of α5-nAChR in association with increased migration and invasion of human lung cancer A549 cell. Treatment of cells with α5-nAChR specific siRNA blocks nicotine-stimulated activation of α5-nAChR and suppresses A549 cell migration and invasion. Reduction of α5-nAChR resulted in upregulation of E-cadherin, consistent with E-cadherin being inhibitive of cancer cell invasion. These findings suggest that nicotine-induced migration and invasion may occur in a mechanism through activation of α5-nAChR, which can contribute to metastasis or development of human lung cancer.

Search for Non-Volatile Components with Low Polarity Characterizing Tobacco Leaves Using Liquid Chromatography / Atmospheric Pressure Chemical Ionization Mass Spectrometry Detector

SUMMARY There has been focus on the components with low polarity in tobacco leaf resin due to their probable relation with taste and aroma of tobacco products, the lack of a feasible analytical method and instrument has long been an obstacle to identifying the components with low polarity. The author thereby paid attention to the analysis employing nonaqueous reversed-phase chromatography hyphenated with a photo diode array detector and an atmospheric pressure chemical ionization mass spectrometry detector which has been considered applicable to the separation of significant but unknown non-volatile. The application succeeded in simultaneously separating, detecting and quantifying more than 100 non-volatile components with different low polarity such as solanesols, triacylglycerols, phytosterols, and chlorophylls. However, their compositional differences among various tobacco leaves still remained partial knowledge based on targeted analysis instead of global knowledge based on comprehensive analysis. No investigation searching for key components elucidating different tastes, aromas, species, cultivars, curing processes, and growing districts among tobacco leaves has been carried out so far. For this reason, all the quantification data were consolidated to form complete multidimensional matrix and were statistically processed to observe the categories and the key components of various tobacco leaves by principal component analysis and hierarchical clustering analysis. Tobacco leaves were first classified into three categories consisting of flue-cured Virginia, air-cured leaf, and Oriental. Solanesyl esters, phytosteryl esters and solanachromene contributed to the category of flue-cured Virginia, while air-cured leaf was characterized by free phytosterols. Oriental was featured by chlorophyll in addition to the contributory components to flue-cured Virginia. Non-volatile components with low polarity seemed to be degraded during curing process and to therefore characterize the different curing processes among various tobacco leaves.

Association of MMP7 −181A→G Promoter Polymorphism with Gastric Cancer Risk: INFLUENCE OF NICOTINE IN DIFFERENTIAL ALLELE-SPECIFIC TRANSCRIPTION VIA INCREASED PHOSPHORYLATION OF cAMP-RESPONSE ELEMENT-BINDING PROTEIN (CREB)

Elevated expression of matrix metalloproteinase7 (MMP7) has been demonstrated to play a pivotal role in cancer invasion. The -181A→G (rs11568818) polymorphism in the MMP7 promoter modulates gene expression and possibly affects cancer progression. Here, we evaluated the impact of -181A→G polymorphism on MMP7 promoter activity and its association with gastric cancer risk in eastern Indian case-control cohorts (n = 520). The GG genotype as compared with the AA genotype was predisposed (p = 0.02; odds ratio = 1.9, 95% confidence interval = 1.1-3.3) to gastric cancer risk. Stratification analysis showed that tobacco addiction enhanced gastric cancer risk in GG subjects when compared with AA subjects (p = 0.03, odds ratio = 2.46, and 95% confidence interval = 1.07-5.68). Meta-analysis revealed that tobacco enhanced the risk for cancer more markedly in AG and GG carriers. Activity and expression of MMP7 were significantly higher in GG than in AA carriers. In support, MMP7 promoter-reporter assays showed greater transcriptional activity toward A to G transition under basal/nicotine-induced/cAMP-response element-binding protein (CREB) overexpressed conditions in gastric adenocarcinoma cells. Moreover, nicotine (a major component of tobacco) treatment significantly up-regulated MMP7 expression due to enhanced CREB phosphorylation followed by its nuclear translocation in gastric adenocarcinoma cells. Furthermore, chromatin immunoprecipitation experiments revealed higher binding of phosphorylated CREB with the -181G than the -181A allele. Altogether, specific binding of phosphorylated CREB to the G allele-carrying promoter enhances MMP7 gene expression that is further augmented by nicotine due to increased CREB phosphorylation and thereby increases the risk for gastric cancer.

Evaluation of Genotoxicity in Women Bidi Rollers Using Comet Assay

A study was conducted on a group of employees from small scale bidi rolling industries in three different districts of telangana state were tested for comet tail lengths that are well established as indicators of early biological effects. To investigate whether occupational exposure to tobacco dust is genotoxic, a total of 182 women bidi workers and 182 control groups of individuals in the age group of 16 to 65 years and 6-30 yrs of tobacco dust exposure were recruited; a questionnaire based survey was conducted. In the present study, the assessment of Primary DNA damage hosted by peripheral blood leukocytes of workers employed in tobacco based bidi rolling industry was performed using the alkaline comet assay, the tail length and long-tailed nuclei thereby being the primary outcome of the measure . A significant increase in the incidence of DNA damage was observed in the experimental subjects when compared to their respective controls. The processing of tobacco leaves generates a lot of dust and facilitates the release of numerous tobacco components in to ambient air. The results obtained in this investigation indicate that bidi rollers seem to be facing the occupational hazard of genotoxicity due to inhalation and handling of bidi tobacco dust.