Lung Carcinogen Research Articles

Abstract 3815: Cellular oxidative stress and immunological effects of carbon-based nanomaterials towards lung carcinogenicity

Abstract Lung cancer accounts for most number of cancer related death, reporting over 26.5% of all cancer deaths in United States alone. Among the risk factors, along with smoking, occupational as well as environmental exposure of carcinogens is considered as major driver of lung cancer in most cases. In that context, high aspect ratio nanomaterials (HARNs) with low density, such as carbon nanotubes (CNTs), remain efficient air-borne particulate matters during every step of their life cycle, from production to usage to disposal. Consequently, inhalation and potentially carcinogenic nanomaterial exposure to pulmonary tissues are anticipated, which may considerably facilitate lung cancer occurrence and mortality. Apart from pulmonary interaction, nanomaterial exposure via skin or oral route may play a significant role in adverse human health effects, especially when the use of nanomaterials in food and cosmetic industries are growing exponentially. CNTs are made of flat sheets of sp2 hybridized carbon atoms layered in hexagonal geometry that are rolled into unified cylindrical structures. CNTs are subdivided into single-walled (SWCNT), double-walled (DWCNT), or multi-walled carbon nanotube (MWCNT) based on the number of carbon layers in nanotubes. Size of CNTs can range from one to several nanometers in diameter and up to several micrometers in length, exhibiting a fibrous-like length-to-width (aspect) ratio similar to asbestos fibers and potentially harbor asbestos-like pulmonary fibrosis and lung cancer risks associated with their long-term exposure. Considerable efforts has been made to study Nano-toxicity but how cellular toxicological and immunological responses are affected by nanomaterial exposure is largely unknown. The present study investigated the effects of different CNT exposure on cellular proliferation, uptake, oxidative stress, DNA damage, Stem cell-like properties along with activation of cellular innate immune responses of human lung epithelial cells and immune cells to determine the underlying cross-talks. Using a physiologically relevant long-term-low-dose exposure model, we found that both single-walled and multi-walled carbon nanotubes, induced particle-specific cellular proliferation, tumor sphere formation, reactive oxygen species (ROS) and super oxide (SO), DNA-strand breaks, mitochondrial depolarization and reduced apoptosis, indicating the genotoxicity and carcinogenic potential of CNTs. We also determined distinct immune activation signature in these cells upon CNTs exposure that closely resembles “immune mediated” carcinogenesis signature as reported in “Inflammatory Cancer (C3)” subtypes. Finally, through in silico analyses and validation we have determined potential CNT exposure induced immune effectors to devise better targeted therapeutic intervention against nanomaterial exposure induced carcinogenesis. Citation Format: Rajib Ghosh, Liying W. Rojanasakul, Yon Rojanasakul. Cellular oxidative stress and immunological effects of carbon-based nanomaterials towards lung carcinogenicity [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3815.

Abstract 3395: Commute patterns, residential traffic-related air pollution, and lung cancer risk in the prospective UK Biobank cohort study

Abstract Introduction: Commuting to and from work is a daily activity that exposes millions of people to lung carcinogens such as particulate matter, polycyclic aromatic hydrocarbons, and other constituents of traffic-related air pollution (TRAP). Lung cancer is a global health burden and one of the most common malignancies among industrialized western countries such as the United Kingdom (UK). Few epidemiologic studies of TRAP and lung cancer consider the contribution of commute characteristics. To further investigate, we assessed associations between commute patterns, residential nitrogen dioxide (NO2; a surrogate marker for TRAP), and lung cancer risk in the prospective UK Biobank cohort study. Methods: We analyzed 234,124 employed participants at baseline in 2006-2010. There were 493 incident lung cancer cases diagnosed over an average 7-year follow-up. Subjects were cross-classified into exclusive categories of commute mode (automobile, public transportation, walking, cycling, active mixture, and other mixture) and frequency (regular: <5, often: ≥5 work-bound trips/week). Annual average residential NO2 concentrations in 2005-2007 were estimated from land use regression. Cox regression models were used to estimate associations between commute patterns, quartiles of NO2, and incident lung cancer, adjusted for age, sex, smoking status, race/ethnicity, study center, body mass index, annual income, commute distance, and alcohol intake. Additional analyses were stratified by age, sex, smoking status, NO2 (>, ≤ median2005=28.3 µg/m3) and main job duration (>, ≤10 years). Effect modification was tested using interaction terms. Results: Most participants only used automobiles to commute (56.5%), while 8.3% only used public transportation (e.g., buses, light-rail, subways), 2.2% only cycled, and 5.0% only walked. Compared to regular automobile use, commuting often by public transportation was strongly associated with increased lung cancer risk (HR=1.68, 95% CI: 1.14-2.47). The association was nominally stronger among high-NO2 residences, men, and ever-smokers, while similar by job duration. There was evidence for effect modification of the association by residential NO2 (p-interaction=0.03) and sex-smoking status (p-interactions=0.03 and 0.09 for former- and current-smoking men, respectively). The other commute categories were not associated with risk. Furthermore, there was a positive exposure-response relationship with NO2 (HRQ2=1.23, 95% CI:0.91-1.65; HRQ3=1.51, 95% CI:1.12-2.03; HRQ4=1.61, 95% CI:1.15-2.27; p-trend=2.1 × 10−3). Conclusions: Our findings suggest that commuters who often use public transportation have elevated lung cancer risk, possibly driven by time spent in transit microenvironments with high TRAP-levels. Although there are health benefits of public transit use, the competing risk of lung cancer warrants consideration. Citation Format: Jason Yat-Yang Wong, Rena Jones, Bryan Bassig, Batel Blechter, Wei Hu, Bu-tian Ji, Nathaniel Rothman, Qing Lan. Commute patterns, residential traffic-related air pollution, and lung cancer risk in the prospective UK Biobank cohort study [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3395.

Downregulation of hedgehog-interacting protein (HHIP) contributes to hexavalent chromium-induced malignant transformation of human bronchial epithelial cells.

Hexavalent chromium [Cr(VI)] is a potent human lung carcinogen. Multiple mechanisms have been proposed that contribute to Cr(VI)-induced lung carcinogenesis including oxidative stress, DNA damage, genomic instability and epigenetic modulation. However, the molecular mechanisms and pathways mediating Cr(VI) carcinogenicity have not been fully elucidated. Hedgehog (Hh) signaling is a key pathway that plays important roles in the formation of multiple tissues during embryogenesis and in the maintenance of stem cell populations in adults. Dysregulation of Hh signaling pathway has been reported in many human cancers. Here, we report a drastic reduction in both mRNA and protein levels of hedgehog-interacting protein (HHIP), a downstream target and a negative regulator of Hh signaling, in Cr(VI)-transformed cells. These findings point to a potential role of Hh signaling in Cr(VI)-induced malignant transformation and lung carcinogenesis. Cr(VI)-transformed cells exhibited DNA hypermethylation and silencing histone marks in the promoter region of HHIP, indicating that an epigenetic mechanism mediates Cr(VI)-induced silencing of HHIP. In addition, the major targets of Hh signaling (GLI1-3 and PTCH1) were significantly increased in Cr(VI)-transformed cells, suggesting an aberrant activation of Hh signaling in these cells. Moreover, ectopically expressing HHIP not only suppressed Hh signaling but also inhibited cell proliferation and anchorage-independent growth in Cr(VI)-transformed cells. In conclusion, these findings establish a novel regulatory mechanism underlying Cr(VI)-induced lung carcinogenesis and provide new insights for developing a better diagnostic and prognostic strategy for Cr(VI)-related human lung cancer.

Toxicity studies of abrasive blasting agents administered by inhalation to F344/NTac rats and Sprague Dawley (Hsd:Sprague Dawley SD) Rats.

Abrasive blasting, commonly known as sandblasting, involves forcibly projecting a stream of abrasive particles through compressed air or steam against a surface to change its quality or to remove contaminants. Silica blasting sand contains high levels of crystalline silica--which can cause pulmonary fibrosis (silicosis) after exposure through inhalation and is considered a lung carcinogen--and constitutes approximately 63% of all abrasives used in abrasive blasting. Other abrasives, including specular hematite, are recommended as alternative blasting agents. Due to the health risks associated with using blasting sand in the abrasive blasting process and the lack of toxicity data on alternatives to blasting sand, the National Institute for Occupational Safety and Health (NIOSH) proposed testing blasting sand and alternative abrasives to characterize their associated toxicity. (Abstract Abridged).

Abstract IA22: Impact of workplace exposures on cancer disparities

Abstract Workplace exposures can have a big impact on cancer disparities. Perhaps the earliest lens through which disparities were examined was through the UK “Registrar-General’s Social Classes,” which were introduced in 1913. These six classes were based on occupation ranging from “professional occupations” to “unskilled occupations” and were predictive of mortality. One can think of these occupational groups representing both education and income, but they also represent power, control, social prestige/status, and mobility, as well as differential exposure to a wide range of workplace carcinogens. While nonoccupational behavioral risk factors could potentially confound the relationship between social class based on occupation and cancer, adjustment for these factors often does not remove associations. For example, in IARC’s Synergy project, a pooled analysis of lung cancer case-control studies, strong associations between Treiman’s Standard International Occupational Prestige Scale and International Socio-Economic Index of Occupational Status remained after adjustment for smoking. In studies of occupational cancer, our focus has most often been on “skilled manual” and “semi-skilled” occupations, because it has been easier to document exposure and their employment by either large companies or unionization facilitates recruitment. Although potentially carcinogenic exposures can occur among a wide range of occupations, the risk is not spread evenly. For example, exposure to common workplace lung carcinogens such as asbestos, diesel exhaust, crystalline silica, nickel, and chromium remains prevalent among workers in construction, transportation, mining, and certain manufacturing and service industries, and very rare among managerial, professional, and sales workers. Although the first occupational chemical carcinogen identified was soot, to which chimney sweeps were exposed as child workers, few studies have focused on the lowest, most vulnerable social class because of difficulties recruiting and other practical challenges. For example, studies of pesticides and cancer have most often recruited farmers and pesticide applicators, and not the more vulnerable farm workers, particularly migrant workers. Other examples of vulnerable groups with potentially carcinogenic exposures are electronic waste, nail salon, and cleaning workers. Further studies of cancer among these vulnerable groups are needed. Citation Format: Paul A. Demers. Impact of workplace exposures on cancer disparities [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr IA22.

Abstract A41: Assessing the effect of glucobrassicin-rich Brussels sprouts on the metabolism of deuterated phenanthrene: Developing food-based chemoprevention of tobacco-related lung cancer

Abstract Introduction: Indole-3-carbinol (I3C) and 3,3-´diindolylmethane (DIM), derived from the glucosinolate glucobrassicin, are found in cruciferous vegetables. I3C and DIM possess a potent chemopreventive effect against the development of tobacco carcinogen-induced lung tumors in mice. Polycyclic aromatic hydrocarbons (PAH) are potent lung carcinogens present in high levels in tobacco smoke. An individual’s ability to metabolically activate and/or detoxify PAH may be related to lung cancer risk from smoking. We hypothesize that I3C administered by eating a rational dose of Brussels sprouts, defined in terms of glucobrassicin concentration, can decrease the metabolic activation and/or increase detoxification of PAH, represented by the noncarcinogenic PAH [D10]Phenanthrene ([D10]Phe). Use of deuterated phenanthrene eliminates confounding by environmental phenanthrene. Metabolic activation of [D10]Phe is represented by [D10]Phenanthrene tetraol ([D10]PheT), and detoxification is represented by [D10]phenanthrol. We are conducting a clinical trial to determine whether glucobrassicin-rich Brussels sprouts can favorably modify the metabolism of the [D10]Phe. Study Design: This is a single-arm clinical trial. The primary objective is to determine the effect of a 7-day course of Brussels sprout consumption on [D10]PheT. Secondary objectives include analysis of [D10]phenanthrol and the [D10]PheT:[D10]phenanthrol ratio. Exploratory objectives include determining the correlation between 24 h urinary DIM with the reduction in [D10]PheT, and determining the effect of Brussels sprout consumption on circulating immune cell composition and activity. Forty-eight generally healthy, adult current smokers and former smokers will be enrolled. Subjects are given 1 microgram of [D10]phe, and all urine is collected for 6 hours (h) afterwards to quantify baseline levels of [D10]PheT and [D10]phenanthrol. Subjects then consume 200 micromol glucobrassicin in the form of raw Brussels sprouts (~200-300 g) once daily for 7 days. Urine is collected for 24 h after vegetable consumption on days 3 ± 1 and 6 of the feeding intervention for DIM quantification. On day 7 of the feeding intervention, a second dose of 1 microgram of [D10]phe is administered at the study center 60 minutes ± 10 minutes after vegetable consumption, followed by another 6 h urine collection. [D10]pheT and [D10]phenanthrol levels are quantified using a validated tandem mass spectrometry assay. Pre- and post-[D10]PheT levels are compared using a paired t-test after log transformation. The results will also be analyzed by GSTT1 and GSTM1 genotyping. Results: Twelve subjects have completed the study. Baseline [D10]PheT levels ranged from 48.34 to 331.05 pmol/6 h. Day 7 [D10]PheT levels ranged from 26.57 to 333.35 pmol/6 h. Percent change from baseline to Day 7 [D10]PheT ranged from a 33% decrease to an 86.5% increase (mean +/- SE of 12.8 +/- 11.6%). Conclusions: The study is ongoing and more subjects are necessary to make a definitive conclusion. Citation Format: Naomi Fujioka, Michelle To, Bruce R. Lindgren, Vincent A. Fritz, Charles Rohwer, Dorothy Hatsukami, Stephen S. Hecht. Assessing the effect of glucobrassicin-rich Brussels sprouts on the metabolism of deuterated phenanthrene: Developing food-based chemoprevention of tobacco-related lung cancer [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr A41.

Respirable Crystalline Silica Exposure, Smoking, and Lung Cancer Subtype Risks. A Pooled Analysis of Case-Control Studies.

Rationale: Millions of workers around the world are exposed to respirable crystalline silica. Although silica is a confirmed human lung carcinogen, little is known regarding the cancer risks associated with low levels of exposure and risks by cancer subtype. However, little is known regarding the disease risks associated with low levels of exposure and risks by cancer subtype.Objectives: We aimed to address current knowledge gaps in lung cancer risks associated with low levels of occupational silica exposure and the joint effects of smoking and silica exposure on lung cancer risks.Methods: Subjects from 14 case-control studies from Europe and Canada with detailed smoking and occupational histories were pooled. A quantitative job-exposure matrix was used to estimate silica exposure by occupation, time period, and geographical region. Logistic regression models were used to estimate exposure-disease associations and the joint effects of silica exposure and smoking on risk of lung cancer. Stratified analyses by smoking history and cancer subtypes were also performed.Measurements and Main Results: Our study included 16,901 cases and 20,965 control subjects. Lung cancer odds ratios ranged from 1.15 (95% confidence interval, 1.04-1.27) to 1.45 (95% confidence interval, 1.31-1.60) for groups with the lowest and highest cumulative exposure, respectively. Increasing cumulative silica exposure was associated (P trend < 0.01) with increasing lung cancer risks in nonsilicotics and in current, former, and never-smokers. Increasing exposure was also associated (P trend ≤ 0.01) with increasing risks of lung adenocarcinoma, squamous cell carcinoma, and small cell carcinoma. Supermultiplicative interaction of silica exposure and smoking was observed on overall lung cancer risks; superadditive effects were observed in risks of lung cancer and all three included subtypes.Conclusions: Silica exposure is associated with lung cancer at low exposure levels. An exposure-response relationship was robust and present regardless of smoking, silicosis status, and cancer subtype.

Prolonged exposure to particulate Cr(VI) is cytotoxic and genotoxic to fin whale cells

BackgroundHexavalent chromium [Cr(VI)] is a human lung carcinogen and global marine pollutant. High Cr concentrations, resembling the ones observed in occupationally exposed workers, have been observed in fin whales (Balaenoptera physalus) in the Gulf of Maine. This outcome suggests Cr might be disrupting the health of fin whale populations. Indeed, Cr in acute (24 h) exposure does cause toxicity in fin whale cells. However, human cell culture data indicate prolonged exposures (120 h) induce a higher amount of toxicity compared to 24 h exposure due to an inhibition of homologous recombination repair. However, whether prolonged exposure causes similar outcomes in fin whale cells is unknown. ObjectiveDue to the importance of assessing prolonged exposure toxicity, this study focuses on characterizing acute and prolonged exposure of Cr(VI) in male and female fin whale cells. MethodsCytotoxicity was measured by the clonogenic assay, also known as colony forming assay, which measures the ability of cells to proliferate and form colonies after the treatment. DNA double strand breaks were analyzed by neutral comet assay. Clastogenicity was measured using the chromosome aberration assay. Intracellular Cr levels were measured with Graphite Furnace Atomic Absorption Spectrometry (GFAAS) with Syngistix Software. ResultsIn this study, we demonstrate that particulate Cr(VI) induces cytotoxicity and genotoxicity in a treatment-dependent manner after 24 h and 120 h exposures. Cytotoxicity levels were generally low with relative survival above 64 %. DNA double strand break data and chromosome aberration data were elevated after a 24 h exposure, but decreased after a 120 h exposure. While cytotoxicity was similar after 24 h and 120 h exposures, less DNA double strand breaks and chromosomal instability occurred with prolonged exposure. ConclusionParticulate Cr(VI) is cytotoxic and genotoxic to fin whale cells after acute and prolonged exposures. The reduction of genotoxicity we have observed after 120 h exposure may be partly explained by lower intracellular Cr levels after 120 h. However, the decrease in intracellular levels is not reflected by a similar decrease in chromosome aberrations suggesting other mechanisms may be at play. Male fin whale cells appear to be more susceptible to the genotoxic effects of particulate Cr(VI) while female cells are less susceptible possibly due to increased cell death of damaged cells, but more work is needed to clarify if this outcome reflects a sex difference or interindividual variability. Overall, the study shows particulate Cr(VI) does induce toxicity at both acute and prolonged exposures in fin whales cells indicating Cr(VI) exposure is a health risk for this species.

Sex-specific risks and trends in lung cancer mortality across occupations and economic activities in Switzerland (1990–2014)

ObjectivesTo assess lung cancer mortality across occupations and economic activities/industries in Switzerland using three statistical estimates.MethodsAll Swiss residents aged 18–65 during the 1990 or 2000 censuses were followed through 2014...

Investigation of diffusive transport of radon through bricks

Radon and their progeny are known indoor lung carcinogens with major sources from the subsoil followed by building materials. The present work was aimed to study the radon permeability of main building materials which is a dominant process for radon entry to indoor environment under normal room conditions. For this purpose, the radon diffusion coefficient and permeability for widely used bricks in the southern coastal region of India were measured with a specially designed twin-chamber experimental set up: a strong source of radon in one chamber and radon and progeny accumulation arrangement in another chamber. Brick samples (with varying thicknesses, firing time and porosity) collected from local kilns were sandwiched between the chambers allowing the radon gas to diffuse through them to get developed in the second chamber. An alpha scintillation based radon monitoring device was connected with both chambers for online radon measurement. Moderately- and lightly-fired bricks show relatively greater permeability than the highly-fired ones, but all the studied bricks are found to be in the radon-tight category. Measured data of radon diffusion coefficient (0.29–0.40) × 10−6 m2s-1 with a mean of (0.35 ± 0.05) × 10−6 m2s-1 and diffusion length (0.37–0.44 m) with a mean of 0.41 ± 0.03 m show a general agreement with the available results in the literature, albeit differing with an earlier study by Chauhan et al. (2008) due to the variation of the sample matrix. Measured data may help the building construction agency to choose a suitable brick to ensure a safer indoor environment for the dwellers.

Assessing the Impact of Housing Features and Environmental Factors on Home Indoor Radon Concentration Levels on the Navajo Nation.

Uranium is naturally found in the environment as a radioactive metal element with high concentrations in the Southwestern US. In this region is the Navajo Nation, which spans approximately 69,930 square kilometers. A decay product of uranium is radon gas, a lung carcinogen that has no color, odor, or taste. Radon gas may pass from soil into homes; and, indoor accumulation has been associated with geographical location, seasonality, home construction materials, and home ventilation. A home and indoor radon survey was conducted from November 2014 through May 2015, with volunteers who reported residence on the Navajo Nation. Home geolocation, structural characteristics, temperature (°C) during radon testing, and elevation (meters) were recorded. Short-term indoor radon kits were used to measure indoor radon levels. 51 homes were measured for indoor radon levels, with an arithmetic mean concentration of 60.5 Becquerels per cubic meter (Bq/m3) (SD = 42.7). The mean indoor radon concentrations (Bq/m3) by house type were: mobile, 29.0 (SD = 22.9); wood, 58.6 (SD = 36.0); hogan, 74.0 (SD = 0.0); homes constructed of cement and wood, 82.6 (SD = 3.5); and homes constructed of concrete and cement, 105.7 (SD = 55.8). A key observation is that house construction type appears to be associated with the mean home indoor radon concentration. This observation has been published in that the basic structural make-up of the home may affect home ventilation and therefore indoor radon concentration levels.

Time‐dependent Inhibition of Cytochrome P450 2A13 (CYP2A13): by Cinnamaldehyde as a Lung Cancer Preventive Agent

Nicotine is the addictive substance found in various tobacco products CYP2A13, an enzyme localized in the lungs, metabolizes tobacco‐specific nitrosamine carcinogens that contribute to lung cancer. Therefore, pinpointing CYP2A13 inhibitors is an approach to lower tobacco‐based lung cancer risk. Cinnamaldehyde is a common flavoring agent in the fluids of electronic nicotine vaping devices. Cinnamaldehyde was found to be a potent inhibitor of CYP2A6, another enzyme that metabolizes nicotine. Because CYP2A13 and CYP2A6 exhibit overlap in substrate/inhibitor selectivity, the goal here was to evaluate the inhibition of CYP2A13 by cinnamaldehyde. A time‐dependent inhibition coumarin assay was performed to determine the kinetic parameters for cinnamaldehyde in recombinant CYP2A13. Primary incubations contained cinnamaldehyde (5 to 200 micromolar) of (or DMSO for control), CYP2A13 Supersomes, and potassium phosphate buffer. Incubations were initiated with NADPH. Secondary incubations contained coumarin, NADPH, and potassium phosphate buffer. At selected time points (0 to 18 minutes), an aliquot of the primary incubation mixture was transferred to the secondary incubation tubes, which were terminated with trichloroacetic acid after heating at 37 degree C for 5.5 minutes. A linearity study o was conducted to determine the appropriate termination time. CYP2A13 activity was measured by detection of hydroxycoumarin using high performance liquid chromatography (HPLC) and a fluorescence detector. Standard curves of hydroxycoumarin were used to quantify product formation from experimental samples.Hydroxycoumarin formation decreased with time and inhibitor concentrations. Maximal inhibition following a 18 minute incubation was 38.3 ± 1.6 and 4.0 ± 0.6 % at 20 and 200 micromolar cinnamaldehyde, respectively. The maximal rate of inhibition was 0.109 per minute. The results provide evidence that cinnamaldehyde is a time‐dependent inhibitor of CYP2A13. Furthermore, cinnamaldehyde appears to be a more potent inhibitor of CYP2A13 than CYP2A6, based on the maximal rate of inhibition (0.109 and 0.056 per minute, respectively). The results imply that cinnamaldehyde could interfere with the bioactivation of nitrosamine lung carcinogens.. Additional kinetic studies are needed to confirm the results of this study, and to evaluate the safety and toxicity profiles of cinnamaldehyde in more complex physiological models.Figure 1 Standard Curve (7‐OH‐Coumarin) Percent uM Area uM Stds 1 Stds 2 Average Change Stds 1 4 1.1E+07 4 1.1E+07 11028898 11028898 0.0 2 5684098 2 5684098 5684098 5684098 0.0 Slope 2,764,695.99 1 2773892 1 2773892 2784915 2779404 0.4 Y‐intercept 29,108.47 0.5 1410325 0.5 1410325 1425656 1417991 1.1 R2 0.9998 0.25 713352 0.25 713352 724841 719097 1.6 0.125 355993 0.125 355993 364369 360181 2.4 0.0625 181197 0.0625 181197 182438 181818 0.7 0.03125 92767 0.03125 92767 92341 92554 −0.5 Stds 2 4 1.1E+07 AUC E 20 200 E 20 200 2 5684098 0 966263 897472 321950 873055 768870 272624 1 2784915 3 810370 715528 193710 871857 651272 169610 0.5 1425656 6 862911 554828 144832 3746286 804730 133450 0.25 724841 9 884632 520572 119480 841174 461582 109707 0.125 364369 12 853112 496090 87451 834152 423436 81136 0.0625 182438 15 871382 390425 76171 799519 326200 85743 0.03125 92341 18 855074 279226 66930 761978 340103 60431 OH‐Cou Concentration E 20 200 E 20 200 0 0.339 0.314 0.106 0.305 0.268 0.088 3 0.283 0.248 0.060 0.305 0.225 0.051 6 0.302 0.190 0.042 1.345 0.281 0.038 9 0.309 0.178 0.033 0.294 0.156 0.029 12 0.298 0.169 0.021 0.291 0.143 0.019 15 0.305 0.131 0.017 0.279 0.107 0.020 18 0.299 0.090 0.014 0.265 0.112 0.011

Generation and characterization of a serum albumin‐humanized mouse model for biomarker discovery

The aim of this study is to develop a serum albumin‐humanized mouse model, for identifying human protein biomarkers of exposure to hazardous xenobiotics. The albumin‐humanized mouse was generated via cross‐breeding between a human albumin‐transgenic mouse and an albumin‐null mouse. The ability of human and mouse albumins to react with metabolites of the lung carcinogen 4‐(methylnitrosamino)‐l‐(3‐pyridyl)‐1‐butanone (NNK) was compared. Adult albumin‐humanized mice and wild‐type mice were treated with NNK (100 mg/kg body weight, IP). Blood, liver, and lung were analyzed 6 hours after NNK treatment. The NNK metabolite 4‐hydroxy‐l‐(3‐pyridyl)‐1‐butanone (HPB), free or as albumin‐HPB adduct, was detected in the plasma, whereas the O6‐methyl‐deoxyguanosine (O6‐mdG) DNA adduct, formed via NNK bioactivation, was detected in lung and liver. Results of quantitative analyses revealed lower levels of O6‐mdG in tissues of the humanized mice (10.4 and 85.5 pmol/μmol guanine, for lung and liver, respectively) than in wild‐type mice (18.4 and 240 pmol/μmol guanine, for lung and liver, respectively), a difference possibly explained by differing pharmacokinetic profiles of NNK. Interestingly, although a substantial genotype‐related difference was not observed in free HPB levels in the plasma (0.31 and 0.39 ng/ml, for wild‐type and humanized, respectively), human albumin‐HPB adduct levels in the humanized mouse were 6X higher than mouse albumin‐HPB adduct levels in the wild‐type mouse (per mg albumin). These data suggest that human and mouse albumins have different reactivities with reactive NNK metabolites and they illustrate the utility of the albumin‐humanized mouse model for biomarker discovery.Support or Funding InformationSupported in part by NIH grant CA092596

Silica and asbestos exposure at work and the risk of bladder cancer in Canadian men: a population-based case-control study

BackgroundSilica and asbestos are recognized lung carcinogens. However, their role in carcinogenesis at other organs is less clear. Clearance of inhaled silica particles and asbestos fibers from the lungs may lead to translocation to sites such as the bladder where they may initiate carcinogenesis. We used data from a Canadian population-based case-control study to evaluate the associations between these workplace exposures and bladder cancer.MethodsData from a population-based case-control study were used to characterize associations between workplace exposure to silica and asbestos and bladder cancer among men. Bladder cancer cases (N = 658) and age-frequency matched controls (N = 1360) were recruited within the National Enhanced Cancer Surveillance System from eight Canadian provinces (1994–97). Exposure concentration, frequency and reliability for silica and asbestos were assigned to each job, based on lifetime occupational histories, using a combination of job-exposure profiles and expert review. Exposure was modeled as ever/never, highest attained concentration, duration (years), highest attained frequency (% worktime) and cumulative exposure. Odds ratios (OR) and their 95% confidence intervals (CI) were estimated using adjusted logistic regression.ResultsA modest (approximately 20%) increase in bladder cancer risk was found for ever having been exposed to silica, highest attained concentration and frequency of exposure but this increase was not statistically significant. Relative to unexposed, the odds of bladder cancer were 1.41 (95%CI: 1.01–1.98) times higher among men exposed to silica at work for ≥27 years. For asbestos, relative to unexposed, an increased risk of bladder cancer was observed for those first exposed ≥20 years ago (OR:2.04, 95%CI:1.25–3.34), those with a frequency of exposure of 5–30% of worktime (OR:1.45, 95%CI:1.06–1.98), and for those with < 10 years of exposure at low concentrations (OR:1.75, 95%CI:1.10–2.77) and the lower tertile of cumulative exposure (OR:1.69, 95%CI:1.07–2.65). However, no clear exposure-response relationships emerged.ConclusionsOur results indicate a slight increase in risk of bladder cancer with exposure to silica and asbestos, suggesting that the effects of these agents are broader than currently recognized. The findings from this study inform evidence-based action to enhance cancer prevention efforts, particularly for workers in industries with regular exposure.

The permissive role of TCTP in PM2.5/NNK-induced epithelial\u2013mesenchymal transition in lung cells

BackgroundTranslationally controlled tumor protein (TCTP) is linked to lung cancer. However, upon lung cancer carcinogens stimulation, there were no reports on the relationship between TCTP and lung cell carcinogenic epithelial–mesenchymal transition (EMT). This study was designed to investigate the molecular mechanism of regulation of TCTP expression and its role in lung carcinogens-induced EMT.MethodsTo study the role of TCTP in lung carcinogens [particulate matter 2.5 (PM2.5) or 4-methylnitrosamino-l-3-pyridyl-butanone (NNK)]-induced EMT, PM2.5/NNK-treated lung epithelial and non-small cell lung cancer (NSCLC) cells were tested. Cell derived xenografts, human lung cancer samples and online survival analysis were used to confirm the results. MassArray assay, Real-time PCR and Reporter assays were performed to elucidate the mechanism of regulation of TCTP expression. All statistical analyses were performed using GraphPad Prism version 6.0 or SPSS version 20.0.ResultsTranslationally controlled tumor protein and vimentin expression were up-regulated in PM2.5/NNK-treated lung cells and orthotopic implantation tumors. TCTP expression was positively correlated with vimentin in human NSCLC samples. Patients with high expression of TCTP displayed reduced overall and disease-free survival. TCTP overexpression could increase vimentin expression and promote cell metastasis. Furthermore, PM2.5/NNK stimulation brought a synergistic effect on EMT in TCTP-transfected cells. TCTP knockdown blocked PM2.5/NNK carcinogenic effect. Mechanically, PM2.5/NNK-induced TCTP expression was regulated by one microRNA, namely miR-125a-3p, but not by methylation on TCTP gene promoter. The level of TCTP was regulated by its specific microRNA during the process of PM2.5/NNK stimulation, which in turn enhanced vimentin expression and played a permissive role in carcinogenic EMT.ConclusionsOur results provided new insights into the mechanisms of TCTP regulatory expression in lung carcinogens-induced EMT. TCTP and miR-125a-3p might act as potential prognostic biomarkers and therapeutic targets for NSCLC.

Laryngeal Cancer Risks in Workers Exposed to Lung Carcinogens: Exposure-Effect Analyses Using a Quantitative Job Exposure Matrix.

Various established occupational lung carcinogens are also suspected risk factors for laryngeal cancer. However, individual studies are often inadequate in size to investigate this relatively rare outcome. Other limitations include imprecise exposure assessment and inadequate adjustment for confounders. This study applied a quantitative job exposure matrix (SYN-JEM) for four established occupational lung carcinogens to five case-control studies within the International Head and Neck Cancer Epidemiology Consortium. We used occupational histories for 2256 laryngeal cancer cases and 7857 controls recruited from 1989 to 2007. We assigned quantitative exposure levels for asbestos, respirable crystalline silica, chromium-VI, and chromium-VI and nickel combined (to address highly correlated exposures) via SYN-JEM. We assessed effects of occupational exposure on cancer risk for males (asbestos, respirable crystalline silica, chromium-VI, and chromium-VI and nickel combined) and females (asbestos and respirable crystalline silica), adjusting for age, study, tobacco smoking, alcohol consumption, and asbestos exposure where relevant. Among females, odds ratios (ORs) were increased for ever versus never exposed. Among males, P values for linear trend were <0.05 for estimated cumulative exposure (all agents) and <0.05 for exposure duration (respirable crystalline silica, chromium-VI, and chromium-VI and nickel combined); strongest associations were for asbestos at >90th percentile cumulative exposure (OR = 1.3, 95% confidence interval [CI] = 1.0, 1.6), respirable crystalline silica at 30+ years duration (OR = 1.4, 95% CI = 1.2, 1.7) and 75th-90th percentile cumulative exposure (OR = 1.4, 95% CI = 1.1, 1.8), chromium-VI at >75th percentile cumulative exposure (OR = 1.9, 95% CI = 1.2, 3.0), and chromium-VI and nickel combined at 20-29 years duration (OR = 1.5, 95% CI = 1.1, 2.2). These findings support hypotheses of causal links between four lung carcinogens (asbestos, respirable crystalline silica, chromium-VI, and nickel) and laryngeal cancer.

Deubiquitinase USP7-mediated MCL-1 up-regulation enhances Arsenic and Benzo(a)pyrene co-exposure-induced Cancer Stem Cell-like property and Tumorigenesis.

Rationale: MCL-1 is up-regulated in cancer and a target for cancer treatment. How MCL-1 is up-regulated and whether MCL-1 up-regulation plays a role in tumorigenic process is not well-known. Arsenic and benzo(a)pyrene (BaP) are well-recognized lung carcinogens and we recently reported that arsenic and BaP co-exposure acts synergistically in inducing cancer stem cell (CSC)-like property and lung tumorigenesis. This study was performed to further investigate the underlying mechanism focusing on the role of MCL-1.Methods: The spheroid formation assay and nude mouse tumorigenesis assay were used to determine the CSC-like property and tumorigenicity of arsenic plus BaP co-exposure-transformed human bronchial epithelial BEAS-2B cells, respectively. Biochemical, pharmacological and genetic approaches were used to manipulate gene expressions, dissect signaling pathways and determine protein-protein interactions. Both loss-of-function and gain-of-function approaches were used to validate the role of MCL-1 in arsenic plus BaP co-exposure-enhanced CSC-like property and tumorigenicity.Results: Arsenic plus BaP co-exposure-transformed cells express significantly higher protein levels of MCL-1 than the passage-matched control, arsenic or BaP exposure alone-transformed cells. Knocking down MCL-1 levels in arsenic plus BaP co-exposure-transformed cells significantly reduced their apoptosis resistance, CSC-like property and tumorigenicity in mice. Mechanistic studies revealed that arsenic plus BaP co-exposure up-regulates MCL-1 protein levels by synergistically activating the PI3K/Akt/mTOR pathway to increase the level of a deubiquitinase USP7, which in turn reduces the level of MCL-1 protein ubiquitination and prevents its subsequent proteasome degradation.Conclusions: The deubiquitinase USP7-mediated MCL-1 up-regulation enhances arsenic and BaP co-exposure-induced CSC-like property and tumorigenesis, providing the first evidence demonstrating that USP7 stabilizes MCL-1 protein during the tumorigenic process.

P101 - The role of L- and D-menthol in the glucuronidation and detoxification of the major lung carcinogen, NNK

P101 - The role of L- and D-menthol in the glucuronidation and detoxification of the major lung carcinogen, NNK

Airborne Levels of Lung Carcinogens at an Ascon Manufacturing Site

ABSTRACT We assessed the airborne concentrations of the dust (both total and respirable), quartz, polycyclic aromatic hydrocarbons, and elemental carbon in an ascon manufacturing environment to determine the exposure to operators and the likelihood of developing occupational respiratory disease. The Ascon production process is divided into four stages, namely, feeding, drying, mixing, and loading. During the feeding stage, the aggregate is transferred via hoppers to underground conveyors. The drying process removes moisture from the aggregate and maintains the required temperature for combining the aggregate, asphalt, and additives into ascon during the mixing stage. Finally, the ascon is disgorged from an outlet on the mixing machine and loaded onto dump trucks. The airborne concentrations of the total dust, respirable dust, and quartz measured at Hopper 1 and Hopper 6 were 8.540, 1.536, and 0.125 mg m–3, and 10.092, 3.989, and 0.331 mg m–3, respectively. The amounts of respirable dust and quartz by the vibrating screen totaled 12.362 and 1.645 mg m–3, respectively, and that of elemental carbon near a dryer burner equaled 0.001 mg m–3. The levels of the total dust, respirable dust, and quartz at the mixer outlet and in the dump truck zone were observed to be 0.685, 0.265, and 0.011 mg m–3, and 0.419, 0.036, and 0.011 mg m–3, respectively. Of the measured substances, only naphthalene was found at concentrations significantly lower than the permissible exposure limit (10 ppm), reaching only 0.274, 0.138, 0.192, and 0.237 ppm for the dryer burner, dump truck zone, dump truck waiting zone, and operational room, respectively. The conveyors on the ground, vibratory sieve, Bunker C oil tank, and mixer also exhibited very low concentrations of naphthalene—0.074, 0.088, 0.080, and 0.074 ppm, respectively. Relatively low levels of personal exposure to the total and the respirable dust (0.027 and 0.013 mg m–3) were measured during the operational tasks. However, operators were exposed to higher levels of respirable dust and quartz, 4.260 and 0.548 mg m–3, while cleaning the underground conveyors. Based our results, we conclude that whereas PAHs are emitted at very low concentrations during ascon production, quartz-containing aggregate dust is released in large quantities. This study presents the first environmental evaluation at an ascon production facility in terms of substances that cause lung cancer.

Low-moderate arsenic exposure and respiratory in American Indian communities in the Strong Heart Study

BackgroundArsenic exposure through drinking water is an established lung carcinogen. Evidence on non-malignant lung outcomes is less conclusive and suggests arsenic is associated with lower lung function. Studies examining low-moderate arsenic (< 50 μg/L), the level relevant for most populations, are limited. We evaluated the association of arsenic exposure with respiratory health in American Indians from the Northern Plains, the Southern Plains and the Southwest United States, communities with environmental exposure to inorganic arsenic through drinking water.MethodsThe Strong Heart Study is a prospective study of American Indian adults. This analysis used urinary arsenic measurements at baseline (1989–1991) and spirometry at Visit 2 (1993–1995) from 2132 participants to evaluate associations of arsenic exposure with airflow obstruction, restrictive pattern, self-reported respiratory disease, and symptoms.ResultsAirflow obstruction was present in 21.5% and restrictive pattern was present in 14.4%. The odds ratio (95% confidence interval) for obstruction and restrictive patterns, based on the fixed ratio definition, comparing the 75th to 25th percentile of arsenic, was 1.17 (0.99, 1.38) and 1.27 (1.01, 1.60), respectively, after adjustments, and 1.28 (1.02, 1.60) and 1.33 (0.90, 1.50), respectively, based on the lower limit of normal definition. Arsenic was associated with lower percent predicted FEV1 and FVC, self-reported emphysema and stopping for breath.ConclusionLow-moderate arsenic exposure was positively associated with restrictive pattern, airflow obstruction, lower lung function, self-reported emphysema and stopping for breath, independent of smoking and other lung disease risk factors. Findings suggest that low-moderate arsenic exposure may contribute to restrictive lung disease.