Carcinogens In Tobacco Smoke Research Articles

Time to First Cigarette and 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanol (NNAL) Levels in Adult Smokers; National Health and Nutrition Examination Survey (NHANES), 2007–2010

The time to first cigarette (TTFC) is a good indicator of several dimensions of nicotine dependence. An early TTFC is also associated with increased lung and oral cancer risk. Our objective was to determine the relationship between TTFC and exposure to tobacco smoke carcinogens. We conducted a cross-sectional analysis of a nationally representative subsample of smoking adults that had urinary samples analyzed for tobacco biomarkers. The study included 1,945 participants from the 2007-2008 and 2009-2010 National Health and Nutrition and Examination Survey. The main outcome measure was creatinine-adjusted urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels. The cigarette-per-day adjusted levels of NNAL were twice as high in participants who smoked within 5 minutes after waking than in participants who refrained from smoking for at least 1 hour (0.58 vs. 0.28 ng/mL, P < 0.001). In multivariate linear models, a shorter TTFC was significantly associated with increasing NNAL levels, after adjusting for cigarettes smoked per day (or cotinine), secondhand smoke exposure, age, sex, race/ethnicity, and other potential confounders. These data show that in a nationally representative sample, there is a dose-dependent relationship between earlier smoking in the day and higher biologic exposure to a tobacco smoke carcinogen. Our study provides further evidence that highlights the relationship between TTFC, nicotine dependence, and cancer risk.

1127 QUANTIFICATION OF MAJOR BLADDER CARCINOGENS - ACROLEIN AND AMINOBIPHENYL-INDUCED DNA ADDUCTS IN NORMAL HUMAN UROTHELIAL MUCOSA AND BLADDER TUMOR TISSUE

You have accessJournal of UrologyBladder Cancer: Basic Research (III)1 Apr 20131127 QUANTIFICATION OF MAJOR BLADDER CARCINOGENS - ACROLEIN AND AMINOBIPHENYL-INDUCED DNA ADDUCTS IN NORMAL HUMAN UROTHELIAL MUCOSA AND BLADDER TUMOR TISSUE Hyun-Wook Lee, Hsiang-Tsui Wang, Mao-wen Weng, Yan Liu, William C. Huang, Nicholas Donin, Xue-Ru Wu, Herbert Lepor, and Moon-shong Tang Hyun-Wook LeeHyun-Wook Lee New York, NY More articles by this author , Hsiang-Tsui WangHsiang-Tsui Wang New York, NY More articles by this author , Mao-wen WengMao-wen Weng New York, NY More articles by this author , Yan LiuYan Liu New York, NY More articles by this author , William C. HuangWilliam C. Huang New York, NY More articles by this author , Nicholas DoninNicholas Donin New York, NY More articles by this author , Xue-Ru WuXue-Ru Wu New York, NY More articles by this author , Herbert LeporHerbert Lepor New York, NY More articles by this author , and Moon-shong TangMoon-shong Tang New York, NY More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.742AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Tobacco smoke (TS) is the major cause of bladder cancer (BC) in the US; BC incidence in tobacco smokers is 5-fold higher than in nonsmokers. TS contains 2 chemicals, 4-hydroxy-aminobiphenyl (ABP) and acrolein (Acr) that cause BC in animal models. Since ABP is a major cause of occupation-related BC and ABP-DNA adducts have been found in human bladder tissue, it has long been suspected that ABP is a major human bladder carcinogen in TS. While the amount of ABP in TS is minute (<5 ng/cigarette), the amount of Acr in TS is more than 100,000-fold higher than ABP. Moreover, Acr can form Acr-deoxyguanosine (Acr-dG) adducts that are mutagenic and can inhibit DNA repair and enhance DNA damage-induced mutations. Since inhaled Acr is excreted in urine, we hypothesize that Acr may initiate bladder carcinogenesis. As a first step to test this hypothesis we quantify Acr and ABP induced DNA adducts in normal human urothelium and in BC tissues. METHODS We developed 2 methods for quantification of Acr-dG and ABP-DNA adducts in human bladder tissues: 1) chemistry method using 32P post-labeling the adducted nucleotides followed by 2- and 4-dimensional thin layer chromatography and high performance liquid chromatography, and 2) immunochemical method using monoclonal antibody against Acr-dG adducts as first antibody and labeling the second antibody with quantum dot. We determined the levels of Acr-dG and ABP-DNA adducts in 20 normal human urothelial mucosa samples and in 10 BC samples. RESULTS Both methods can quantify Acr-dG and ABP-DNA adduct levels and yield comparable results. The immunochemical method is 40-fold more sensitive than the chemistry method. Acr-dG adduct levels are 20-100-fold higher than ABP-DNA adduct levels in both normal urothelium and BC tissues, and Acr-dG levels in BC tissues are 2-fold higher than in normal urothelium. CONCLUSIONS The levels of Acr-DNA adducts in normal human urothelium are 20-100 times higher than ABP-DNA adduct levels, and Acr-dG levels in BC tissues are 2 times higher than in normal urothelium. These results support the hypothesis that Acr is a major bladder carcinogen, and will have a major impact on bladder cancer risk assessment and design of new BC prevention strategies. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e460-e461 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Hyun-Wook Lee New York, NY More articles by this author Hsiang-Tsui Wang New York, NY More articles by this author Mao-wen Weng New York, NY More articles by this author Yan Liu New York, NY More articles by this author William C. Huang New York, NY More articles by this author Nicholas Donin New York, NY More articles by this author Xue-Ru Wu New York, NY More articles by this author Herbert Lepor New York, NY More articles by this author Moon-shong Tang New York, NY More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Novel selective catalyst derived from uniform clustered NaY zeolite microspheres

The design and preparation of a new “self-protected” zeolite catalyst are reported in this paper for the first time, in order to face the challenges arising from environmental protection, in selective catalytic degrading of tobacco specific nitrosamine (TSNA) carcinogens in environmental tobacco smoke (ETS). A new method to synthesize NaY zeolite with uniform microsphere morphology via an organic amine TMAOH as bifunctional template is reported in this study. The spherical zeolite is prepared by a one-step hydrothermal crystallization without any post-treatment or other shape-directing agent. It has a rugged surface like a cluster of crystal grains and its crystallization process is monitored in detail by means of XRD and SEM. To assess how the zeolite morphology affects its catalytic performance in complex systems, this material was directly mixed with tobacco shred and added into cigarettes to in situ degrade TSNA in smoke. As a result, the clustered zeolite microsphere can avoid the interference of particulate matter in smoke and shows a high selectivity in the removal of TSNA. This synthetic method offers a novel way of preparing zeolites with a spherical morphology, which has great potential application in the fields of catalysis, adsorption and separation.

The Food and Drug Administration's Regulation of Tobacco: The Center for Tobacco Products' Office of Science

The Family Smoking Prevention and Tobacco Control Act (TCA) was signed into law on June 22, 2009, and provided the Food and Drug Administration (FDA) broad regulatory authority with respect to the manufacture, marketing, and distribution of tobacco products. The three public health goals of the Center for Tobacco Products (CTP), FDA, are to prevent youth initiation of tobacco use, decrease harm and/or addictiveness of tobacco products, and encourage tobacco use cessation. The CTP has established an Office of Science to ensure that sound science exists with which to develop regulatory actions. Although there is a vast and sound science base with regard to numerous provisions within the TCA, new research will not only help assess the impact of FDA regulatory authority over tobacco products but will inform future regulatory activities. In order to meet the broad science demands within the TCA, the CTP developed seven research priority areas: 1understanding the diversity of tobacco products; 2reducing addiction to tobacco products; 3reducing toxicity and carcinogenicity of tobacco products and smoke; 4understanding adverse health consequences of tobacco use; 5understanding communications about tobacco products; 6understanding tobacco product marketing; and 7understanding economics and policies on tobacco use and perceptions.

DNA and protein adducts in human tissues resulting from exposure to tobacco smoke

Tobacco smoke contains a variety of genotoxic carcinogens that form adducts with DNA and protein in the tissues of smokers. Not only are these biochemical events relevant to the carcinogenic process, but the detection of adducts provides a means of monitoring exposure to tobacco smoke. Characterization of smoking-related adducts has shed light on the mechanisms of smoking-related diseases and many different types of smoking-derived DNA and protein adducts have been identified. Such approaches also reveal the potential harm of environmental tobacco smoke (ETS) to nonsmokers, infants and children. Because the majority of tobacco-smoke carcinogens are not exclusive to this source of exposure, studies comparing smokers and nonsmokers may be confounded by other environmental sources. Nevertheless, certain DNA and protein adducts have been validated as biomarkers of exposure to tobacco smoke, with continuing applications in the study of ETS exposures, cancer prevention and tobacco product legislation. Our article is a review of the literature on smoking-related adducts in human tissues published since 2002.

FDA's Tobacco Products Research Program likely to play role in cancer prevention

Editor's note: This is Part 2 of a 2-part series on cancer prevention research. Part 1 was published in the June 1 issue of “CancerScope.” When the Family Smoking Prevention and Tobacco Control Act (TCA) became law in 2009, giving the US Food and Drug Administration (FDA) the power to regulate tobacco products, the FDA created the Center for Tobacco Products. The center's principal mission is to regulate the manufacture, marketing, and distribution of tobacco products. According to David Ashley, PhD, director of the center's Office of Science, scientific research is necessary to inform the FDA's regulations, which involve reducing initiation, promoting cessation, and reducing harms for those who use tobacco products. Understanding the diversity of tobacco products; Reducing addiction to tobacco products; Reducing the toxicity and carcinogenicity of tobacco products and smoke; Understanding the adverse health consequences of tobacco use; Understanding communications about tobacco products; Understanding tobacco product marketing; and Understanding how economics and policies affect tobacco product use. Center representatives add that scientists also can submit basic research proposals if they can inform regulatory issues. Within this framework, the FDA recently announced 56 questions they would like to see answered through research. (For the full list of questions, visit the Center for Tobacco Products' summary of its meeting on research priorities at www.fda.gov/TobaccoProducts and click on “News & Events.”) “They're growing a regulatory and research arm from scratch, in a paradigm that's totally foreign to the FDA,” says Peter Shields, MD, president of the American Society of Preventive Oncology and deputy director at the Lombardi Comprehensive Cancer Center at Georgetown University Medical Center. “If they applied any of the rules they use for drugs or food to tobacco, they would get rid of it, but the law prohibits them from banning it.” Because Congress will never ban tobacco, the FDA is trying to limit as much as possible the harm of tobacco products, he says. “Tobacco research has been underfunded for 20 years, and now the FDA needs data that doesn't exist,” says Dr. Shields. “There are fundamental, basic questions that need to be answered.” National Study Will Assess Regulation Impact The first large-scale FDA/National Institutes of Health (NIH) study to be announced since the FDA gained authority to regulate tobacco products is a national study of tobacco users to monitor and assess the behavioral and health impacts of new government tobacco regulations. The effort is a collaboration between the NIH's National Institute on Drug Abuse and the Center for Tobacco Products. What makes people susceptible to tobacco use; Use patterns and resulting health problems; Patterns of tobacco cessation and relapse in the era of tobacco regulation; The effects of regulatory changes on risk perceptions and other tobacco-related attitudes; and Differences in attitudes, behaviors, and key health outcomes in racial/ethnic, gender, and age subgroups. Tobacco research has been underfunded for 20 years, and now the FDA needs data that doesn't exist. There are fundamental, basic questions that need to be answered.—Peter Shields, MD Knowledge gleaned from this study will help the FDA target the most effective actions to decrease the toll of tobacco use on the nation's health, said Margaret Hamburg, FDA commissioner, when the study was announced last fall. More specifically, the results will help the FDA assess the impact of the TCA and understand how best to use its regulatory authority regarding product marketing and standards and communicating the risks of tobacco use. Additional Efforts Similar to the Department of Defense funding breast cancer research, the FDA is contracting with the NIH to award additional grants. Among the questions to be answered is whether the FDA should regulate levels of nicotine. In addition, researchers need to test the blood and urine of people using the new tobacco products to understand their impact. Tobacco companies claim these products reduce carcinogens, but scientists currently do not have those tests. As a result, the best options now are testing individuals for certain biomarkers and developing and validating specific modeling that will determine how regulators can best impact public health, Dr. Shields says. Researchers also need to understand how people use the new products and what they think of them. Clinical trials are difficult to conduct because the typical tobacco user does not want to participate in a trial, Dr. Shields adds. “Tobacco is a complex problem that's been around a long time, and it won't be solved overnight,” he says.

Comparative metabolism of benzo[a]pyrene by human keratinocytes infected with high-risk human papillomavirus types 16 and 18 as episomal or integrated genomes

Background:Infection with human papillomavirus (HPV) is a critical factor in the development of cervical cancer. Smoking is an additional risk factor. Tobacco smoke carcinogens, such as benzo[a]pyrene (B[a]P), and their cytochrome P450-related metabolites are present in significantly higher levels in the cervical mucus of women smokers than in nonsmokers. We determined the metabolism and P450 expression of B[a]P-treated human keratinocytes infected with HPV-16 or -18.Materials and Methods:Monolayer cultures of uninfected primary human foreskin keratinocytes, human vaginal and cervical keratinocytes carrying episomal genomes of HPV-16 and -18, respectively, and invasive cervical carcinoma cell lines carrying either HPV-16 or -18 genomes integrated into the host DNA, were incubated with 0.1 μM [3H]B[a]P. The resulting oxidative metabolites were analyzed and quantified by radioflow high-performance liquid chromatography. Additionally, all cell lines were incubated with unlabeled 0.1 μM B[a]P for Western blot analysis of cytochrome P450 1A1 and 1B1.Results:Significant enhancement in levels of both detoxification and activation metabolites was found in incubations with all types of HPV-infected cells compared with control incubations (P < 0.05). The highest capacity to metabolize B[a]P was observed with cells containing integrated HPV-18 genomes. Induction of cytochrome 1B1 was observed in HPV-16 and -18 integrated, and in HPV-16 episomal cell types.Conclusions:Both viral genotype and genomic status in the host cell affect B[a]P metabolism and cytochrome P450 1B1 expression. An increase of DNA-damaging metabolites might result from exposure of HPV-infected women to cigarette smoke carcinogens.

Novel selective adsorbent derived from hierarchical rockery-like MCM-41 monolith

The design and preparation of a new “self-protected” mesoporous adsorbent is reported for the first time, in order to selectively adsorb tobacco specific nitrosamine (TSNA) carcinogens in environmental tobacco smoke (ETS). Hierarchical rockery-like MCM-41 monoliths with the tunable hollow structure and macropores are synthesized under special conditions by controlling the formation and connection of primary particles: through self-assembly and flow induced orientation, the initial formed prism-like primary particles are compelled to form circular disc- or ellipse-like secondary structures, and these domains connect together to form flats that are linked by small flats to yield units on millimeter scale, finally these units are randomly crooked to generate monoliths at centimeter level. These monolithic materials have similar textural properties, surface state and the same primary particles as common MCM-41, but they exhibit unique selectivity in the capture of TSNA in cigarette smoke. They also avoid unnecessary trapping of accompanying particles, which is realized for the first time because of the morphology-induced new function, opening a new way to create superior selectivity in complicated adsorption processes, where the target is adhered on the particles in a gas stream.

Mutagenesis and carcinogenesis induced by dibenzo[a,l]pyrene in the mouse oral cavity: a potential new model for oral cancer.

Cancer of the oral cavity is a serious disease, affecting about 30,000 individuals in US annually. There are several animal models of oral cancer, but each has certain disadvantages. As a new model, we investigated whether topical application of the tobacco smoke carcinogen, dibenzo[a,l]pyrene (DB[a,l]P) is mutagenic and carcinogenic in the oral cavity of the B6C3F1 lacI and B6C3F1 mouse, respectively. B6C3F1 lacI mice received DB[a,l]P (0, 3, 6, 12 nmol) 3× per week. B6C3F1 mice received the same doses and also 24 nmol. At 38 weeks mutagenesis was measured in oral tissues in lacI mice. For the high dose group, the mutant fraction (MF) in upper mucosa and tongue increased about twofold relative to that in vehicle-alone. The increases were statistically significant. The mutational profile in the DB[a,l]P-induced mutants was compared with that induced by benzo[a]pyrene (BaP) in oral tissue. BaP is mutagenic in many tissues when administered by gavage. The mutational profile for DB[a,l]P was more similar to that reported for p53 mutations in head and neck cancers than was that of BaP. At 47 weeks, oral squamous cell carcinomas (OSCC) were found in 31% of the high-dose B6C3F1 group. Elevations of p53 and COX-2 protein were observed in tumor and dysplastic tissue. As DB[a,l]P induces mutations and tumors in the oral cavity, and has a mutational profile in oral tissue similar to that found in p53 in human OSCC, the treatment protocol described here may represent a new and relevant model for cancer of the oral cavity.

Abstract B41: A mouse model for inflammation-driven lung tumorigenesis

Abstract The link between chronic inflammation and cancer development has lately gained extensive epidemiological and experimental support, particularly in organs like liver, stomach, colon, and lung. Although experimental models are available to study inflammation-driven tumorigenesis in the liver, stomach, and colon, no such models are available for lung cancer. Therefore, the objective of the present study is to develop a model for inflammation-driven lung tumorigenesis. A/J mice received four intraperitoneal injections (two doses/week) of the tobacco smoke carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) at a dose level of 50 mg/kg body weight. Beginning one week after the last dose of NNK, the mice were given weekly intranasal instillations of lipopolysaccharide (LPS, 10ug/mouse), a potent inflammation-inducing agent, until the end of the study at week 27. Upon termination of the study, tumors on the surface of the lung were counted, their size determined and histopathologically analyzed. Moreover, we analyzed alterations in the expression of inflammation- and tumorigenesis-related proteins and microRNAs (miRs) by Western immunoblotting and qRT-PCR, respectively. Chronic exposure NNK-treated mice to LPS increased the number and size of lung tumors (47.3 ± 11 tumors/mouse for the NNK plus LPS group versus 28 ± 8 tumors/mouse in the NNK only group). Furthermore, lung tumors in the NNK plus LPS treated mice were significantly larger than the lung tumors of the mice challenged with NNK alone. Multiplicities of lung tumors in LPS-treated mice were similar to those mice given the vehicle. Multiplicities of the histopathological lesions pulmonary hyperplastic foci, adenoma, adenoma with dysplasia and adenocarcinoma in the NNK only group were 3.0 ± 1.2, 7.1 ± 2.9, 1.3 ± 1.1, and 0.3 ± 0.5/mouse, respectively. The corresponding frequencies of the lesions in the NNK plus LPS group were 3.1 ± 1.8, 11.8 ± 5.2, 3.9 ± 1.8, and 0.6 ± 0.7/mouse. Western immunoblotting studies showed that LPS exposure of NNK-treated mice enhanced activation of NF-kappaB, STAT3, and Akt but caused down-regulation of the tumor suppressor protein PTEN. Further, analyses of levels of five carcinogenesis-related microRNAs (miR-21, miR-146a, miR-150, miR-155 and miR-21, and miR-181b-1) showed increases in the expressions of miR-155 and miR-21. Levels of miR-155 and miR-21 were increased by 2.3-fold and 1.9-fold, respectively, in mice treated with NNK plus LPS group as compared to mice treated with NNK. Moreover, levels of miR-155 and miR-21 were increased by 10.5-fold and 4.7-fold, respectively, in LPS treated mice compared to vehicle-treated mice. In summary, our results demonstrate that LPS-induced chronic lung inflammation enhances lung tumorigenesis. This model could be a vey useful tool to understand the role inflammation in lung tumorigenesis and for identification of anti-inflammatory and lung cancer chemopreventive agents. Citation Information: Cancer Prev Res 2011;4(10 Suppl):B41.

Glutathione S-transferase (GST) gene polymorphisms, cigarette smoking and colorectal cancer risk among Chinese in Singapore

Cigarette smoking is a risk factor for colorectal cancer. Putative colorectal procarcinogens in tobacco smoke include polycyclic aromatic hydrocarbons and heterocyclic aromatic amines that are known substrates of glutathione S-transferases (GSTs). This study examined the influence of functional GST gene polymorphisms on the smoking-colorectal cancer association in a population known to be minimally exposed to dietary sources of these procarcinogens. Incident cases of colorectal cancer (n = 480) and matched controls (n = 1167) were selected from the Singapore Chinese Health Study, a population-based prospective cohort of 63 257 men and women who have been followed since 1993. We determined the deletion polymorphisms of GSTM1 and GSTT1 and the functional polymorphism at codon 105 of GSTP1 for each subject. A three level composite GST index was used to examine if GST profile affected a smoker's risk of developing colorectal cancer. While there was no statistically significant association between cigarette smoking and colorectal cancer risk among subjects absent of any at-risk GST genotypes, smokers possessing two to three at-risk GST genotypes exhibited a statistically significant increased risk of colorectal cancer compared with non-smokers (P = 0.0002). In this latter stratum, heavy smokers exhibited a >5-fold increased risk relative to never-smokers (odds ratio, 5.43; 95% confidence interval, 2.22-13.23). Subjects with one at-risk GST genotype displayed a statistically significant but weaker association with smoking. These findings suggest that GST gene polymorphisms influence interindividual susceptibility to smoking-associated colorectal cancer. Our data indicate an important role for GST enzymes in the detoxification of colorectal carcinogens in tobacco smoke.

Metabolic study of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone to the enantiomers of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in vitro in human bronchial epithelial cells using chiral capillary electrophoresis

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) with one chiral center at the carbinol is a major metabolite of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). As tobacco specific N-nitrosamines (TSNAs), NNK and NNAL are the most pulmonary carcinogens in tobacco products and smoke. In this paper, a chiral CE method modified with highly sulfated β-cyclodextrin (S-β-CD) was developed to investigate the stereoselective formation of NNAL from NNK in vitro in normal human bronchial epithelial (NHBE) cells. Combined with solid phase extraction (SPE) of the cell samples, NNK and NNAL enantiomers were baseline separated under the proposed CE conditions, with satisfactory recoveries (72.5–113% for NNK and (±)-NNAL) and low limits of detection (LOD, 2.5–3 μg/mL for NNK and (±)-NNAL). The cytotoxicity of NNK in NHBE cells was investigated through the cell counting kit (CCK) assay and proved to be highly dependent on the NNK's concentration. The metabolic results obtained from CE analysis demonstrated that NNK was preferentially metabolized to (+)-NNAL through carbonyl reduction. Meanwhile, the ratio of [(+)-NNAL]/[(−)-NNAL] was independent of NHBE cells’ incubation time with NNK, but could be changed according to the original incubation concentration of NNK. This chiral CE method could be useful for the study on toxicology and metabolic transformations of related TSNAs.

Phenolic fraction of tobacco smoke inhibits BPDE-induced apoptosis response and potentiates cell transformation: role of attenuation of p53 response.

Polynuclear aromatic hydrocarbons (PAHs) present in tobacco smoke are regarded as chemical carcinogens. Previously, we observed that a weakly acidic phenolic fraction of tobacco smoke condensate (TSCPhFr), which is devoid of PAHs, significantly potentiates (±)-anti-BP-7,8-diol-9,10-epoxide (BPDE)-induced anchorage-independent cell growth of promotion-sensitive JB6 cell, indicating its tumor-promoting potential. In the present article, we report that further fractionation of phenolic components from TSCPhFr did not show any significant potentiation of BPDE-induced cell transformation by any of the HPLC-purified phenolic fractions, indicating several phenolic components as a whole are needed for observed activity. Although the tumor-promoting activity of weakly acidic phenolic fraction of tobacco smoke had been indicated long before, no studies have been pursued to understand the mechanism(s) underlying the tumor-promoting activity of TSCPhFr. We observed that BPDE, an ultimate carcinogenic metabolite of tobacco smoke carcinogen benzo[a]pyrene, elicits apoptosis induction, which is significantly inhibited by TSCPhFr. Increased cell transformation and decreased apoptosis by TSCPhFr were associated with attenuation of BPDE-induced p53 accumulation. JB6 cells transfected with p53 siRNA showed significantly less apoptosis induction by BPDE as compared to control cells. In p53 impaired cells (which are observed to have a faster growth rate as compared to normal cells), TSCPhFr has a practically negligible effect on apoptosis induction in response to BPDE. Also, in p53 null HCT116 p53(-/-) cells, BPDE-induced apoptosis is unresponsive to TSCPhFr. Inhibition of BPDE-induced NF-κB activation was also observed by us previously. Interestingly, treatment of cells with NF-κB-specific inhibitor IKK-NBD peptide showed no effect on BPDE-induced apoptosis, whereas TSCPhFr showed moderate inhibition of apoptosis in NF-κB inhibited cells as compared to control cells. Our observations indicate that attenuation of BPDE-induced p53 response has a role in apoptosis inhibition and increased cell transformation by TSCPhFr. These findings have implication with regard to the underlying mechanism of tumor-promoting activity of TSCPhFr in PAH-induced carcinogenesis. Although p53-mediated NF-κB activation has a role in apoptosis induction, the role of NF-κB in TSCPhFr-mediated potentiation of PAH-induced cell transformation is not clear from our studies.

Abstract LB-465: Investigation on chemopreventive effect of lyophilized strawberries in human subjects with precancerous lesions in esophagus: a phase 1b study in China

Abstract Esophageal squamous cell carcinoma (SCC) is the third most common gastrointestinal malignancy and the sixth most frequent cause of cancer death in the world. Nitrosamine carcinogens in tobacco smoke, in the diet, and those produced in the acidic conditions of the stomach, appear to be important causative agents of esophageal SCC. Among these is N-Nitrosomethylbenzylamine (NMBA), present in the diet in China, and likely the most potent nitrosamine carcinogen for the rat esophagus. Our laboratory has used the NMBA-induced esophageal cancer model in rats to identify putative chemopreventive agents, including natural food products, to prevent this disease. Dietary freeze-dried strawberries were found to significantly inhibit tumor development in the rat esophagus by inhibiting the metabolism of NMBA to DNA damaging species and by reducing the growth rate of premalignant cells. Based on these observations, we conducted a Phase I trial in China to investigate the effects of freeze-dried strawberries in a cohort of adult individuals with esophageal dysplastic lesions in a high-risk area for esophageal cancer. In this study, 60 grams of freeze-dried strawberries were given to participants who have been identified by endoscopy to have dysplastic lesions, every day for six months. Biopsy specimens were obtained by endoscopy before and after strawberry treatment. Overall, 36 patients (94.7%) have successfully completed the study, including proper completion of the pre- and post-esophageal endoscopy and biopsy, and the dietary strawberry diary. Twenty patients are females and fifteen patients are males. The average of age is 54.6 ± 1.28. Among 36 patients, 31 patients were diagnosed with mild dysplasia (86.11%) and 5 patients were diagnosed with moderate dysplasia (13.89%). After 6-month strawberry treatment, in patients with mild dysplasia, there was no change in 4 patients, decrease in 26 patients (P &amp;lt; 0.0001) and an increase in 1 patient in histological grade. In patients with moderate dysplasia, there was no change in 2 patients and a decrease in 3 patients in histological grade. Strawberries reduced protein expression levels of inducible nitric oxide synthase (iNOS; 77.3% reduction, P = 0.03), cyclooxygenase-2 (COX-2; 47.3% reduction, P = 0.11), phospho-NFκB-p65 (63.1% reduction, P = 0.23) and phospho-S6 (87.9% reduction, P = 0.02). In addition, we evaluated the effects of strawberries on cell proliferation rate by Ki-67 staining. Strawberries significantly inhibited Ki-67 labeling index by 37.9% (P = 0.023). Our results suggest that strawberries may be a useful alternative to chemopreventive drugs for the prevention of human esophageal cancer. (Supported by California Strawberry Commissions) Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-465. doi:10.1158/1538-7445.AM2011-LB-465

Abstract 955: Specific forms of mutant KRAS predict patient benefit from targeted therapy in the BATTLE-1 clinical trial in advanced non-small cell lung cancer

Abstract Mutant KRAS (mut-KRAS) is present in 17-25% of all human cancers, where it plays a critical role in driving cancer cell growth and resistance to therapy. Despite numerous attempts, there is still no effective therapy for mut-KRAS tumors. Understanding the signaling mechanisms activated by mut-KRAS and finding agents to inhibit mut-KRAS signaling are important unmet needs in cancer therapy today. The recently completed BATTLE-1 clinical trial, a prospective, multi-arm, biopsy-mandated, biomarker-driven, clinical trial in advanced refractory non-small cell lung cancer (NSCLC), found that mut-KRAS did not accurately predict patient outcome (progression-free survival) to targeted intervention. This finding contradicted published evidence for such a relationship from colon cancer and some previous NSCLC studies. We explored more specifically the nature of the KRAS mutations, which are primarily found at codons 12 and 13, where different base substitutions lead to alternate amino acid (aa) substitutions. NSCLC has a much higher proportion of mut-KRAS G12C(cysteine) aa substitutions (47%) due to carcinogens in tobacco smoke, and only 15% mut-KRAS have G12D(aspartate). These data contrast those in other solid tumors, such as colon or pancreas, which predominantly manifest mut-KRAS G12D (50%) and only 9% mut-KRAS G12C. In a subset analysis of the BATTLE-1 data, we showed significantly worse progression-free survival in patients with mut-KRAS G12C, versus other mut-KRAS including G12D (p=.041) and who were treated with erlotinib, vandetanib or sorafenib. In a panel of NSCLC cell lines with known mut-KRAS aa substitutions to identify pathways activated by the different mut-KRAS genotypes, we found that mut-KRAS G12D activates both PI-3-K and MEK signaling, while mut-KRAS G12C does not and alternatively activates PKCζ and RAL signaling. This finding was confirmed in immortalized human bronchial epithelial (HBEC) cells stably transfected with wt-KRAS or different forms of mut-KRAS. Our molecular modeling studies show that the different conformation imposed by mut-KRAS G12C could lead to altered association with downstream signaling transducers, compared to mut-KRAS G12D. The significance of the findings for developing mut-KRAS therapies is profound, since it suggests that not all mut-KRAS may be addictive; and that different combinations of inhibitors of downstream signaling may be needed for different mut-KRAS. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 955. doi:10.1158/1538-7445.AM2011-955

Abstract 5551: Potentiation of PAH-induced cell transformation by phenolic fraction of tobacco smoke: A mechanistic insight

Abstract It is reported that the known content of carcinogenic polynuclear aromatic hydrocarbons (PAHs) in the tobacco smoke condensate (TSC) alone cannot account for the observed carcinogenicity of the TSC tested on mouse skin (Orris, L. et.al., 1958. J. Natl. Cancer Inst., 21: 557-561). The phenolic fraction of TSC (TSCPhFr) which is devoid of PAHs exhibits strong tumor-promoting activity in mouse skin initiated with PAHs (Roe et. al., 1959. Brit. J. Cancer., 13: 623-633). The mechanism(s) underlying the tumor promoting effect of TSCPhFr is not known. In the present communication we report that (±)-anti-BP-7,8-diol-9,10-epoxide (BPDE), an ultimate carcinogenic metabolite of tobacco smoke carcinogen benzo[a]pyrene, elicits both apoptosis induction and cell transformation in promotion sensitive mouse epidermal JB6 cell which has been extensively used for tumor promotion studies. We observed that TSCPhFr significantly potentiates BPDE-induced cell transformation associated with decreased apoptosis response indicating its tumor promoting potential. Increased cell transformation and decreased apoptosis by TSCPhFr was associated with attenuation of BPDE-induced p53 accumulation and NF-κB activation. We examined whether attenuation of p53 and NF-κB responses by TSCPhFr has any role in this regard. Chemical inhibition of p53 in JB6 cells using known p53 inhibitor pifithrin alpha showed potentiation of BPDE-induced p53 accumulation instead of down-regulation as expected. Since pifithrin alpha's role in p53 inhibition is controversial as reported in many studies, we used genomic inhibitor (p53 siRNA) to down-regulate p53 response. We observed that either JB6 cells transfected with p53 siRNA or p53 deficient HCT116 cells (HCT116p53-/−) shows significantly less apoptosis induction and more colony formation on soft agar by BPDE compared to control cells. In p53 impaired both cell lines (which are observed to have faster growth rate compared to normal cells) TSCPhFr has practically negligible effect on apoptosis induction and soft agar colony formation in response to BPDE. Interestingly treatment of cells with IKK-NBD peptide NF-κB-specific inhibitor) has variable effects on BPDE-induced apoptosis induction and cell transformation. Our observations indicate that attenuation of BPDE-induced p53 response by TSCPhFr has a role in apoptosis inhibition and increased cell transformation. These findings have implication with regard to the underlying mechanism of tumor promoting activity of TSCPhFr in PAH-induced carcinogenesis. Although p53 mediated NF-κB activation is involved in DNA damage-induced apoptosis induction as reported by others (Nature 2000, 404:892-897), the role of NF-κB in PAH-induced apoptosis and cell transformation is not clear (supported by NCI grant 1R15CA125630). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5551. doi:10.1158/1538-7445.AM2011-5551

TACE/ADAM-17 Phosphorylation by PKC-Epsilon Mediates Premalignant Changes in Tobacco Smoke-Exposed Lung Cells

BackgroundTobacco smoke predisposes humans and animals to develop lung tumors, but the molecular events responsible for this are poorly understood. We recently showed that signaling mechanisms triggered by smoke in lung cells could lead to the activation of a growth factor signaling pathway, thereby promoting hyperproliferation of lung epithelial cells. Hyperproliferation is considered a premalignant change in the lung, in that increased rates of DNA synthesis are associated with an increased number of DNA copying errors, events that are exacerbated in the presence of tobacco smoke carcinogens. Despite the existence of DNA repair mechanisms, a small percentage of these errors go unrepaired and can lead to tumorigenic mutations. The results of our previous study showed that an early event following smoke exposure was the generation of oxygen radicals through the activation of NADPH oxidase. Although it was clear that these radicals transduced signals through the epidermal growth factor receptor (EGFR), and that this was mediated by TACE-dependent cleavage of amphiregulin, it remained uncertain how oxygen radicals were able to activate TACE.Principal FindingsIn the present study, we demonstrate for the first time that phosphorylation of TACE at serine/threonine residues by tobacco smoke induces amphiregulin release and EGFR activation. TACE phosphorylation is triggered in smoke-exposed lung cells by the ROS-induced activation of PKC through the action of SRC kinase. Furthermore, we identified PKCε as the PKC isoform involved in smoke-induced TACE activation and hyperproliferation of lung cells.ConclusionsOur data elucidate new signaling paradigms by which tobacco smoke promotes TACE activation and hyperproliferation of lung cells.

Acetaldehyde and gastric cancer

Aldehyde dehydrogenase (ALDH2) and alcohol dehydrogenase (ADH) gene polymorphisms associating with enhanced acetaldehyde exposure and markedly increased cancer risk in alcohol drinkers provide undisputable evidence for acetaldehyde being a local carcinogen not only in esophageal but also in gastric cancer. Accordingly, acetaldehyde associated with alcoholic beverages has recently been classified as a Group 1 carcinogen to humans. Microbes are responsible for the bulk of acetaldehyde production from ethanol both in saliva and Helicobacter pylori-infected and achlorhydric stomach. Acetaldehyde is the most abundant carcinogen in tobacco smoke and it readily dissolves into saliva during smoking. Many foodstuffs and 'non-alcoholic' beverages are important but unrecognized sources of local acetaldehyde exposure. The cumulative cancer risk associated with increasing acetaldehyde exposure suggests the need for worldwide screening of the acetaldehyde levels of alcoholic beverages and as well of the ethanol and acetaldehyde of food produced by fermentation. The generally regarded as safe status of acetaldehyde should be re-evaluated. The as low as reasonably achievable principle should be applied to the acetaldehyde of alcoholic and non-alcoholic beverages and food. Risk groups with ADH-and ALDH2 gene polymorphisms, H. pylori infection or achlorhydric atrophic gastritis, or both, should be screened and educated in this health issue. L-cysteine formulations binding carcinogenic acetaldehyde locally in the stomach provide new means for intervention studies.

Active smoking and secondhand smoke increase breast cancer risk: the report of the Canadian Expert Panel on Tobacco Smoke and Breast Cancer Risk (2009)

Four authoritative reviews of active smoking and breast cancer have been published since 2000, but only one considered data after 2002 and conclusions varied. Three reviews of secondhand smoke (SHS) and breast cancer (2004-2006) each came to different conclusions. With 30 new studies since 2002, further review was deemed desirable. An Expert Panel was convened by four Canadian agencies, the Ontario Tobacco Research Unit, the Public Health Agency of Canada, Physicians for a Smoke-Free Canada and the Canadian Partnership Against Cancer to comprehensively examine the weight of evidence from epidemiological and toxicological studies and understanding of biological mechanisms regarding the relationship between tobacco smoke and breast cancer. This article summarises the panel's full report (http://www.otru.org/pdf/special/expert_panel_tobacco_breast_cancer.pdf). There are 20 known or suspected mammary carcinogens in tobacco smoke, and recognised biological mechanisms that explain how exposure to these carcinogens could lead to breast cancer. Results from the nine cohort studies reporting exposure metrics more detailed than ever/never and ex/current smoker show that early age of smoking commencement, higher pack-years and longer duration of smoking increase breast cancer risk 15% to 40%. Three meta-analyses report 35% to 50% increases in breast cancer risk for long-term smokers with N-acetyltransferase 2 gene (NAT2) slow acetylation genotypes. The active smoking evidence bolsters support for three meta-analyses that each reported about a 65% increase in premenopausal breast cancer risk among never smokers exposed to SHS. The Panel concluded that: 1) the association between active smoking and breast cancer is consistent with causality and 2) the association between SHS and breast cancer among younger, primarily premenopausal women who have never smoked is consistent with causality.

What is the biological fate of mentholated cigarette smoking?

What is the biological fate of mentholated cigarette smoking?