Lung cancer biomarkers for the assessment of modified risk tobacco products: an oxidative stress perspective

What Can Current Biomarker Data Tell Us About the Risks of Lung Cancer Posed by Heated Tobacco Products?

INTRODUCTION

Heated tobacco products (HTPs) are marketed as less harmful alternatives to cigarettes, but the lung cancer risk of HTPs is unknown. In the absence of epidemiological data, assessing the risks of HTPs relies on biomarker data from clinical trials. This study examined existing biomarker data to determine what it tells us about the lung cancer risk posed by HTPs.

AIMS AND METHODS

We identified all biomarkers of exposure and potential harm measured in HTP trials and evaluated their appropriateness based on ideal characteristics for measuring lung cancer risk and tobacco use. The effects of HTPs on the most appropriate biomarkers within cigarette smokers switched to HTPs and compared to continued cigarette smoking or cessation were synthesized.

RESULTS

Sixteen out of eighty-two biomarkers (7 exposure and 9 potential harm) measured in HTP trials have been associated with tobacco use and lung cancer, dose-dependently correlated with smoking, modifiable upon cessation, measured within an appropriate timeframe, and had results published. Three of the exposure biomarkers significantly improved in smokers who switched to HTPs and were not significantly different from cessation. The remaining 13 biomarkers did not improve-in some instances worsening upon switching to HTPs-or were inconsistently affected across studies. There were no appropriate data to estimate the lung cancer risk of HTPs in non-smokers.

CONCLUSIONS

The appropriateness of existing biomarker data in assessing lung cancer risk of HTPs, both relative to cigarettes and their absolute risk, is limited. Furthermore, findings on the most appropriate biomarkers were conflicting across studies and largely showed no improvement following a switch to HTPs.

IMPLICATIONS

Biomarker data are fundamental to assessing the reduced risk potential of HTPs. Our evaluation suggests much of the existing biomarker data on HTPs is inappropriate for determining the risk of lung cancer posed by HTPs. In particular, there is a paucity of data on the absolute lung cancer risk of HTPs, which could be obtained from comparisons to smokers who quit and never smokers exposed to or using HTPs. There is an urgent need for further exploration of the lung cancer risks posed by HTPs, via clinical trials and, in the long-term, confirmation of these risks via epidemiological studies. However, careful consideration should be given to biomarker selection and study design to ensure both are appropriate and will provide valuable data.

The Impact of Tobacco Cigarettes, Vaping Products and Tobacco Heating Products on Oxidative Stress

Cells constantly produce oxidizing species because of their metabolic activity, which is counteracted by the continuous production of antioxidant species to maintain the homeostasis of the redox balance. A deviation from the metabolic steady state leads to a condition of oxidative stress. The source of oxidative species can be endogenous or exogenous. A major exogenous source of these species is tobacco smoking. Oxidative damage can be induced in cells by chemical species contained in smoke through the generation of pro-inflammatory compounds and the modulation of intracellular pro-inflammatory pathways, resulting in a pathological condition. Cessation of smoking reduces the morbidity and mortality associated with cigarette use. Next-generation products (NGPs), as alternatives to combustible cigarettes, such as electronic cigarettes (e-cig) and tobacco heating products (THPs), have been proposed as a harm reduction strategy to reduce the deleterious impacts of cigarette smoking. In this review, we examine the impact of tobacco smoke and MRPs on oxidative stress in different pathologies, including respiratory and cardiovascular diseases and tumors. The impact of tobacco cigarette smoke on oxidative stress signaling in human health is well established, whereas the safety profile of MRPs seems to be higher than tobacco cigarettes, but further, well-conceived, studies are needed to better understand the oxidative effects of these products with long-term exposure.

A Pilot Study on the Association of Lead, 8-Hydroxyguanine, and Malondialdehyde Levels in Opium Addicts' Blood Serum with Illicit Drug Use and Non-Addict Persons

While a large body of literature has shown the health problems of illicit drug use, research is needed on how substance abuse impacts DNA damage and contaminants in blood, especially given Pb-contaminated opium. This pilot study aimed to evaluate the levels of lead (Pb), 8-hydroxy di-guanine (8-oxo-Gua), and malondialdehyde (MDA) in the blood serum of opium addicts and non-addict people. The current study is a case–control study with a cross-sectional design. A sample of 50 opium-addicted and non-addict adults were chosen for this study using convenience and random sampling methods. Participants were divided into two groups: addicts and non-addicts. The atomic absorption spectroscopy method was used to measure the quantity of Pb, and the Enzyme-Linked Immunosorbent Assay (ELISA) method was used to measure the amount of 8-oxo-Gua and MDA. The data were analyzed using an independent t-test. The results show that the amount of Pb in the blood serum of addicted women and men was higher than levels in non-addict men and women, for the study participants (p-value = 0.001). Blood levels were not significantly different between addicts and non-addicts for men or women for 8-oxo-Gua (p-value = 0.647 for women and p-value = 0.785 for men) and MDA (p-value = 0.867 for women and p-value = 0.995 for men). In general, addicts’ blood Pb levels were found to be substantially higher than those of normal non-addict persons in this pilot study. As a result, testing for blood Pb levels in addicts may be informative in instances when symptoms are inconclusive.

Pathogenesis of Congenital Malformations: Possible Role of Oxidative Stress

OBJECTIVE

Congenital anomalies are important causes of morbidity and mortality in children. Oxidative stress (OS) is involved in the physiopathology of pregnancy-related congenital malformations. This review summarizes the role of OS in the pathogenesis of congenital malformations; in particular, its purpose is to describe how OS influences the development of heart congenital malformations, oesophageal atresia, biliary atresia, diaphragmatic hernia, and autosomal dominant polycystic kidney disease.

STUDY DESIGN

Systematic review of previous studies about the role of OS in pregnancy and its possible effects in developing of congenital malformations. One electronic database (PubMed) was searched and reference lists were checked.

RESULTS

An imbalance between the production of reactive oxygen species (ROS) and antioxidant defense can occur early in pregnancy and continue in the postnatal life, producing OS. It may destroy the signaling pathways needed for a correct embryogenesis leading to birth defects. In fact, cell functions, especially during embryogenesis, needs specific signaling pathways to regulate the development. These pathways are sensitive to both endogenous and exogenous factors; therefore, they can produce structural alterations of the developing fetus.

CONCLUSION

Because OS plays a significant role in pathogenesis of congenital malformations, studies should be developed in order to better define their OS mechanisms and the beneficial effects of supplemental therapeutic strategies.

KEY POINTS

· Oxidative stress is involved in the pathogenesis of congenital malformations.. · Heart malformations, oesophageal atresia, biliary atresia, diaphragmatic hernia, and autosomal dominant polycystic kidney are analyzed.. · A knowledge of pathomechanism of OS-related congenital malformations could be useful to prevent them..

Relationship Between Urinary 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanol and Lung Cancer Risk in the General Population: A Community-Based Prospective Cohort Study

No published studies have prospectively evaluated the association between urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels and lung cancer risk in the general population. Here, we conducted a prospective community-based cohort study in the Republic of Korea to evaluate the relationship between urinary NNAL levels and lung cancer risk using prediagnostic urine samples. This prospective cohort study was based on the Korean National Cancer Center Community Cohort. During the follow-up period, 173 primary lung cancer cases were identified. Total urinary NNAL levels were measured by liquid chromatography-tandem mass spectrometry, and data were analyzed using multivariable Cox proportional hazards regression models. The risk of lung cancer was significantly increased per unit of natural log-transformed urinary NNAL (HR, 1.27; 95% CI, 1.09-1.48), after adjusting for age, region, entry year into the cohort, education achievement, alcohol consumption status, BMI, smoking status, and urinary cotinine levels. Cox proportional-hazards models with NNAL quartiles also showed positive dose-response relationships with risk of lung cancer. A significantly increased risk of lung cancer was found in the fourth quartile of urinary NNAL levels (HR, 3.27; 95% CI, 1.37-7.79, P for trend < 0.01). After stratification with sex, the significant association remained in only men. Urinary NNAL levels are associated with the risk of lung cancer in the general population, and this association is independent from the quantification of cigarette smoking and nicotine uptake.

Statistical analysis plan for "A randomised, controlled study to evaluate the effects of switching from cigarette smoking to using a tobacco heating product on health effect indicators in healthy subjects"

Tobacco harm reduction strategies aim to substitute smoking with potentially reduced risk products (PRRPs) such as e-cigarettes and tobacco-heating products (THPs). The health benefits of switching from smoking to PRRPs is unknown. A randomised controlled trial is being conducted to increase understanding of the health effects of switching from smoking to a THP in a 12-month long ambulatory study (ISRCTN81075760). Here we describe the study endpoints and the statistical analysis plan. Endpoints are divided into biomarkers of exposure (BoE) to tobacco smoke constituents and health effect indicators related to risk of lung cancer, cardiovascular and obstructive lung disease. These have been selected on the basis of extensive literature evidence. Three primary endpoints, augmentation index (risk factor for cardiovascular disease), total NNAL (linked to lung cancer) and 8-Epi-PGF2α type III (indicator of oxidative stress linked to various diseases), and multiple secondary endpoints will be analysed at 90, 180, and 360 days. Changes from baseline will be compared between study arms by specific contrasts in mixed models. Study wise multiple comparisons adjustments will be performed to account for multiplicity of timepoints and comparisons within timepoints. Generalisability of outcomes will be tested by a sensitivity analysis adjusting for age and gender. Importantly, an ancillary analysis will be performed to assess product compliance during the study based on plasma levels of CEVal, a surrogate marker for acrylonitrile exposure. The rationale underlying the selection of BoEs and health effect indicators, coupled with the statistical analysis plan will be central to understanding the potential health effects of replacing smoking with THP use for one year.

Wood dust and urinary 15-F2t isoprostane in Italian industry workers

Wood dust is one of the most common occupational exposures, with about 3.6 million of workers in the wood industry in Europe. Wood particles can deposit in the nose and the respiratory tract and cause adverse health effects. Occupational exposure to wood dust has been associated with malignant tumors of the nasal cavity and paranasal sinuses. The induction of oxidative stress and the generation of reactive oxygen species through activation of inflammatory cells could have a role in the carcinogenicity of respirable wood dust. Therefore, we conducted a cross-sectional study to evaluate the prevalence of urinary 15-F_2t isoprostane (15-F_2t-IsoP), a biomarker of oxidative stress and peroxidation of lipids, in 123 wood workers compared to 57 unexposed controls living in Tuscany region, Italy. 15-F_2t-IsoP generation was measured by ELISA. The main result of the present study showed that a statistically significant excess of this biomarker occurred in the workers exposed to 1.48 mg/m³ of airborne wood dust with respect to the unexposed controls. The overall mean ratio (MR) between the workers exposed to wood dust and the controls was 1.36, 95% Confidence Interval (C.I.) 1.18-1.57, after correction for age and smoking habits. A significant increment of 15-F_2t-IsoP (43%) was observed in the smokers as compared to the non-smokers. The urinary excretion of 15-F_2t-IsoP was significantly associated with co-exposure to organic solvents, i.e., MR of 1.41, 95% C.I. 1.17-1.70, after adjustment for age and smoking habits. A 41% excess was observed in long-term wood workers, 95% C.I. 1.14-1.75. Multivariate regression analysis showed that the level of 15-F_2t-IsoP was linearly correlated to the length of exposure, regression coefficient (β) = 0.244 ± 0.002 (SE). The overall increment by exposure group persisted after stratification for smoking habits. For instance, in smokers, a 53% excess was detected in the wood workers as compared to the controls, 95% C.I. 1.23-1.91. Our data support the hypothesis that oxidative stress and lipid peroxidation can have a role in the toxicity of wood dust F₂-IsoP measure can be a tool for the evaluation of the effectiveness of targeted interventions aimed to reduce exposures to environmental carcinogens.

How stable is oxidative stress level? An observational study of intra- and inter-individual variability in urinary oxidative stress biomarkers of DNA, proteins, and lipids in healthy individuals

Oxidative stress in humans is affected by the health and nutritional status as well as exposure to external environmental factors. To evaluate the effects of external factors, an assessment of baseline levels as well as diurnal variations in oxidative stress status of healthy individuals is needed. In this study, we examined intra- and inter-individual variability of oxidative stress biomarkers (OSBs) of lipids (malondialdehyde [MDA] and four F₂-isoprostane isomers, namely, 8-isoprostaglandinF_2α [8-PGF_2α], 11β-prostaglandinF_2α [11-PGF_2α], 15(R)-prostaglandinF_2α [15-PGF_2α], and 8-iso,15(R)-prostaglandinF_2α [8,15-PGF_2α]); proteins (o,o'-dityrosine [diY]); and DNA (8-hydroxy-2'-deoxyguanosine [8-OHdG]) in urine from healthy individuals. The significance of creatinine correction, which is typically used to account for urinary dilution, on OSB concentrations was evaluated. Analysis of 515 urine samples, collected longitudinally from 19 healthy individuals daily for over a month, showed inter-individual coefficient of variation (CV) in concentrations from 112% for MDA to 272% for 15-PGF_2α. Intra-individual CV in concentrations ranged from 29% for 8-OHdG to 149% for 15-PGF_2α. MDA was the most abundant OSB found in urine. The intra- and inter-individual variability in F₂-isoprostane concentrations were higher than the values calculated for diY, 8-OHdG, and MDA. All seven OSB concentrations were significantly correlated with each other and with creatinine. Creatinine normalization of OSB concentrations improved predictability in OSB concentrations over time. Our results suggest that 8-OHdG, showing the highest ICC (0.96), yielded more reproducible measurements with a low CV, and is the most suitable biomarker of OSB in spot urine samples. The measured concentrations and diurnal variability in urinary OSB levels in healthy individuals reported in this study are useful as a benchmark for future toxicological and epidemiological studies.

Clinico-epidemiological profile and redox imbalance of lung cancer patients in Algeria

Hypothesis: How are the epidemiologic repartition and the physiopathology of lung cancer (LC) in Algeria? Objective: Our study aimed to establish the clinico-epidemiological profile and evaluate redox imbalance in Algerian patients with LC. Methods and results: Our study concerned 94 Algerian patients with LC treated at two hospitals of Algiers, the capital of Algeria. The clinico-epidemiological profile was established. Moreover, the redox imbalance was evaluated by dosing oxidative stress (OS) parameters in tumor tissues and blood. We noted that the average age was 62.06 years, and 79 among the 94 patients were male, 94.59% of which were smokers. The most common histological type was adenocarcinoma (45.45% of cases), followed by squamous cell carcinoma (37.88%) small-cell carcinoma (4.86%) and other histological types (6.67%), while the most frequent clinical stage was IV (66.95 %). 23 of the 94 patients were exposed to particular risk factors such as masonry products, metal mechanics, coal smoke and so forth. In other respects, the OS parameters: NO (Nitrogen monoxide), AOPP (Advanced Oxidation Protein Products) and MDA (Malondialdehyde) were higher in tumor tissues compared to peritumoral stroma (control), unlike the catalase activity. Otherwise, AOPP and MDA were significantly higher in patients' blood than in healthy control blood, in contrast to the catalase activity. Discussion: The LC has a heterogeneous repartition regarding the sex, age, histological types, the smoking status and professional exposition to risk factors in the Algerian population. Moreover, the oxidative stress impacts the physiopathology of LC.

Simultaneous Analysis of Seven Biomarkers of Oxidative Damage to Lipids, Proteins, and DNA in Urine

The determination of oxidative stress biomarkers (OSBs) is useful for the assessment of health status and progress of diseases in humans. Whereas previous methods for the determination of OSBs in urine were focused on a single marker, in this study, we present a method for simultaneous determination of biomarkers of oxidative damage to lipids, proteins, and DNA. 2,4-Dinitrophenylhydrazine (DNPH) derivatization followed by solid phase extraction (SPE) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) allowed the determination of 8-hydroxy-2'-deoxyguanosine (8-OHdG), o- o'-dityrosine (diY), malondialdehyde (MDA), and four F₂-isoprostane isomers: 8-iso-prostaglandinF_2α (8-PGF_2α), 11β-prostaglandinF_2α (11-PGF_2α), 15( R)-prostaglandinF_2α (15-PGF_2α), and 8-iso,15( R)-prostaglandinF_2α (8,15-PGF_2α) in urine. Derivatization with DNPH and SPE was optimized to yield greater sensitivity and selectivity for the analysis of target chemicals. The limits of detection of target analytes in urine were below 30 pg mL^-1. The assay intra- and interday variability was below 16% of the relative standard deviation, and the recoveries of target chemicals spiked into synthetic urine were near 100%. The method was applied to the analysis of 21 real urine samples, and the analytes were found at a detection frequency of 85% for 8-PGF_2α and 15-PGF_2α, 71% for 11-PGF_2α, 81% for 8,15-PGF_2α, and 100% for diY, 8-OHdG, and MDA. This method offers simultaneous determination of multiple OSBs of different molecular origin in urine samples selectively with high accuracy and precision.

Relationships of salivary cortisol and melatonin rhythms to sleep quality, emotion, and fatigue levels in patients with newly diagnosed lung cancer

PURPOSE

After being diagnosed with lung cancer, patients often experience sleep disturbance, anxiety, depression, and fatigue. These symptoms may occur because of changes in neurotransmitter secretion caused by tumors. This study investigated the correlation of cortisol and melatonin rhythms with sleep quality, anxiety, depression, and fatigue levels in patients with newly diagnosed lung cancer.

METHOD

We conducted a case-control study and recruited 40 patients with newly diagnosed lung cancer and 40 healthy adults.

RESULTS

The patient group had a lower salivary melatonin level and flatter slope (p < 0.001 and p < 0.001), higher salivary cortisol level and steeper slope (p < 0.001 and p < 0.001), higher sleep disturbance level (p = 0.004), and higher depression level (p < 0.001). The multivariate linear regression analysis indicated that the cortisol slope (p = 0.005) and fatigue score (p = 0.032) predicted the sleep quality score (p = 0.011).

CONCLUSION

Overall, the patients with newly diagnosed lung cancer had poorer sleep quality, higher depression levels, lower salivary melatonin levels, higher cortisol levels, and flatter melatonin and cortisol slopes than did the controls. The fatigue level and cortisol slope significantly predicted sleep quality. Therefore, the assessment of cortisol and melatonin rhythms and levels could provide crucial information that may be beneficial for managing symptoms in patients with newly diagnosed lung cancer.

Reduction-oxidation pathways involved in cancer development: a systematic review of literature reviews

Oxidative stress results from an imbalance of the reactive oxygen species/reactive nitrogen species (ROS/RNS) production and the oxidants defense system. Extensive research during the last decades has revealed that oxidative stress can mediate cancer initiation and development by leading not only to molecular damage but also to a disruption of reduction-oxidation (redox) signaling. In order to provide a global overview of the redox signaling pathways, which play a role in cancer formation, we conducted a systematic literature search in PubMed and ISI Web of Science and identified 185 relevant reviews published in the last 10 years. The 20 most frequently described pathways were selected to be presented in this systematic review and could be categorized into 3 groups: Intracellular ROS/RNS generating organelles and enzymes, signal transduction cascades kinases/phosphatases and transcription factors. Intracellular ROS/RNS generation organelles are mitochondria, endoplasmic reticulum and peroxisomes. Enzymes, including NOX, COX, LOX and NOS, are the most prominent enzymes generating ROS/RNS. ROS/RNS act as redox messengers of transmembrane receptors and trigger the activation or inhibition of signal transduction kinases/phosphatases, such as the family members of protein tyrosine kinases and protein tyrosine phosphatases. Furthermore, these reactions activate downstream signaling pathways including protein kinase of the MAPK cascade, PI3K and PKC. The kinases and phosphatases regulate the phosphorylation status of transcription factors including APE1/Ref-1, HIF-1α, AP-1, Nrf2, NF-κB, p53, FOXO, STAT, and β-catenin. Finally, we briefly discuss cancer prevention and treatment opportunities, which address redox pathways and further research needs.

Persistent alterations of gene expression profiling of human peripheral blood mononuclear cells from smokers

The number of validated biomarkers of tobacco smoke exposure is limited, and none exist for tobacco-related cancer. Additional biomarkers for smoke, effects on cellular systems in vivo are needed to improve early detection of lung cancer, and to assist the Food and Drug Administration in regulating exposures to tobacco products. We assessed the effects of smoking on the gene expression using human cell cultures and blood from a cross-sectional study. We profiled global transcriptional changes in cultured smokers' peripheral blood mononuclear cells (PBMCs) treated with cigarette smoke condensate (CSC) in vitro (n = 7) and from well-characterized smokers' blood (n = 36). ANOVA with adjustment for covariates and Pearson correlation were used for statistical analysis in this study. CSC in vitro altered the expression of 1 178 genes (177 genes with > 1.5-fold-change) at P < 0.05. In vivo, PBMCs of heavy and light smokers differed for 614 genes (29 with > 1.5-fold-change) at P < 0.05 (309 remaining significant after adjustment for age, race, and gender). Forty-one genes were persistently altered both in vitro and in vivo, 22 having the same expression pattern reported for non-small cell lung cancer. Our data provides evidence that persistent alterations of gene expression in vitro and in vivo may relate to carcinogenic effects of cigarette smoke, and the identified genes may serve as potential biomarkers for cancer. The use of an in vitro model to corroborate results from human studies provides a novel way to understand human exposure and effect. © 2015 Wiley Periodicals, Inc.

Multiplatform serum metabolic phenotyping combined with pathway mapping to identify biochemical differences in smokers

Aim: Determining perturbed biochemical functions associated with tobacco smoking should be helpful for establishing causal relationships between exposure and adverse events. Results: A multiplatform comparison of serum of smokers (n = 55) and never-smokers (n = 57) using nuclear magnetic resonance spectroscopy, UPLC–MS and statistical modeling revealed clustering of the classes, distinguished by metabolic biomarkers. The identified metabolites were subjected to metabolic pathway enrichment, modeling adverse biological events using available databases. Perturbation of metabolites involved in chronic obstructive pulmonary disease, cardiovascular diseases and cancer were identified and discussed. Conclusion: Combining multiplatform metabolic phenotyping with knowledge-based mapping gives mechanistic insights into disease development, which can be applied to next-generation tobacco and nicotine products for comparative risk assessment.

Oxidative Stress Related Diseases in Newborns

We review oxidative stress-related newborn disease and the mechanism of oxidative damage. In addition, we outline diagnostic and therapeutic strategies and future directions. Many reports have defined oxidative stress as an imbalance between an enhanced reactive oxygen/nitrogen species and the lack of protective ability of antioxidants. From that point of view, free radical-induced damage caused by oxidative stress seems to be a probable contributing factor to the pathogenesis of many newborn diseases, such as respiratory distress syndrome, bronchopulmonary dysplasia, periventricular leukomalacia, necrotizing enterocolitis, patent ductus arteriosus, and retinopathy of prematurity. We share the hope that the new understanding of the concept of oxidative stress and its relation to newborn diseases that has been made possible by new diagnostic techniques will throw light on the treatment of those diseases.

Gene-expression profiles in lung adenocarcinomas related to chronic wood smoke or tobacco exposure

BACKGROUND

Tobacco-smoke is the major etiological factor related to lung cancer. However, other important factor is chronic wood smoke exposure (WSE). Approximately 30 % of lung cancer patients in Mexico have a history of WSE, and present different clinical, pathological and molecular characteristics compared to tobacco related lung cancer, including differences in mutational profiles. There are several molecular alterations identified in WSE associated lung cancer, however most studies have focused on the analysis of changes in several pathogenesis related proteins.

METHODS

Our group evaluated gene expression profiles of primary lung adenocarcinoma, from patients with history of WSE or tobacco exposure. Differential expression between these two groups were studied through gene expression microarrays.

RESULTS

Results of the gene expression profiling revealed 57 statistically significant genes (p < 0.01). The associated biological functional pathways included: lipid metabolism, biochemistry of small molecules, molecular transport, cell morphology, function and maintenance. A highlight of our analysis is that three of the main functional networks represent 37 differentially expressed genes out of the 57 found. These hubs are related with ubiquitin C, GABA(A) receptor-associated like protein; and the PI3K/AKT and MEK/ERK signaling pathways.

CONCLUSION

Our results reflect the intrinsic biology that sustains the development of adenocarcinoma related to WSE and show that there is a different gene expression profile of WSE associated lung adenocarcinoma compared to tobacco exposure, suggesting that they arise through different carcinogenic mechanisms, which may explain the clinical and mutation profile divergences between both lung adenocarcinomas.

Bhas 42 cell transformation activity of cigarette smoke condensate is modulated by selenium and arsenic

Cigarette smoking remains a major health risk worldwide. Development of newer tobacco products requires the use of quantitative toxicological assays. Recently, v-Ha-ras transfected BALB/c3T3 (Bhas 42) cell transformation assay was established that simulates the two-stage animal tumorigenesis model and measures tumor initiating and promoting activities of chemicals. The present study was performed to assess the feasibility of using this Bhas 42 cell transformation assay to determine the initiation and promotion activities of cigarette smoke condensate (CSC) and its water soluble fraction. Further, the modulating effects of selenium and arsenic on cigarette smoke-induced cell transformation were investigated. Dimethyl sulfoxide (DMSO) and water extracts of CSC (CSC-D and CSC-W, respectively) were tested at concentrations of 2.5-40 µg mL(-1) in the initiation or promotion assay formats. Initiation protocol of the Bhas 42 assay showed a 3.5-fold increase in transformed foci at 40 µg mL(-1) of CSC-D but not CSC-W. The promotion phase of the assay yielded a robust dose response with CSC-D (2.5-40 µg mL(-1)) and CSC-W (20-40 µg mL(-1)). Preincubation of cells with selenium (100 nM) significantly reduced CSC-induced increase in cell transformation in initiation assay. Co-treatment of cells with a sub-toxic dose of arsenic significantly enhanced cell transformation activity of CSC-D in promotion assay. The results suggest a presence of both water soluble and insoluble tumor promoters in CSC, a role of oxidative stress in CSC-induced cell transformation, and usefulness of Bhas 42 cell transformation assay in comparing tobacco product toxicities and in studying the mechanisms of tobacco carcinogenesis.

A cross-sectional study of biomarkers of exposure and effect in smokers and moist snuff consumers

Cigarette smoking is a major risk factor for several chronic diseases. Epidemiological data indicate the use of smokeless tobacco (ST) is associated with significantly lower risk for smoking-related diseases compared to cigarettes. Several biomarkers of exposure (BioExp) and effect (BioEff) associated with smoking and use of moist snuff (ST) were evaluated.

A single site, cross-sectional clinical study enrolled three groups of generally healthy male smokers (SMK), moist snuff consumers (MSC), and non-tobacco consumers (NTC), and several BioExp and BioEff were evaluated.

Blood and urinary BioExp, including total nicotine equivalents and tobacco-specific nitrosamines, were higher in MSC compared to SMK. Biomarkers of combustion-related toxicants and cadmium were elevated in SMK. Elevated levels of some BioEff associated with oxidative stress (urinary isoprostanes and leukotriene E4), inflammation (white blood cell count), platelet activation (thromboxane metabolites), and lipid metabolism (apolipoprotein B100 and oxidized low-density lipoprotein) were observed in SMK relative to NTC and MSC (all p<0.05). The non-smoking groups (MSC and NTC) showed similar levels of combustion-related BioExp and BioEff.

Higher levels of exposure to nicotine and some N′-nitrosamines may be observed in MSC, and SMK are exposed to higher levels of combustion-related toxicants. Changes in BioEff consistent with some aspects of inflammation, oxidative stress, and altered lipid metabolism were detected in SMK compared to the non-smoking groups. The biomarker data further improve our understanding of pathophysiological changes and the risk continuum associated with various tobacco products, and could be useful components of future assessments of tobacco products.

Switching from usual brand cigarettes to a tobacco-heating cigarette or snus: Part 3. Biomarkers of biological effect

A randomized, multi-center study of adult cigarette smokers switched to tobacco-heating cigarettes, snus or ultra-low machine yield tobacco-burning cigarettes (50/group) for 24 weeks was conducted. Evaluation of biomarkers of biological effect (e.g. inflammation, lipids, hypercoaguable state) indicated that the majority of consistent and statistically significant improvements over time within each group were observed in markers of inflammation. Consistent and statistically significant differences in pairwise comparisons between product groups were not observed. These findings are relevant to the understanding of biomarkers of biological effect related to cigarette smoking as well as the risk continuum across various tobacco products (ClinicalTrials.gov Identifier: NCT02061917).

The isoprostanes--25 years later

Isoprostanes (IsoPs) are prostaglandin-like molecules generated independent of the cyclooxygenase (COX) by the free radical-induced peroxidation of arachidonic acid. The first isoprostane species discovered were isomeric to prostaglandin F2α and were thus termed F2-IsoPs. Since the initial discovery of the F2-IsoPs, IsoPs with differing ring structures have been identified as well as IsoPs from different polyunsaturated fatty acids, including eicosapentaenoic acid and docosahexanenoic acid. The discovery of these molecules in vivo in humans has been a major contribution to the field of lipid oxidation and free radical research over the course of the past 25 years. These molecules have been determined to be both biomarkers and mediators of oxidative stress in numerous disease settings. This review focuses on recent developments in the field with an emphasis on clinical research. Special focus is given to the use of IsoPs as biomarkers in obesity, ischemia-reperfusion injury, the central nervous system, cancer, and genetic disorders. Additionally, attention is paid to diet and lifestyle factors that can affect endogenous levels of IsoPs. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: analysis and biological relevance."

Cytotoxicity of chronic exposure to 4 cigarette smoke condensates in 2 cell lines

Tobacco use is the leading preventable cause of death. The cytotoxicity of cigarette smoke condensate (CSC), the particulate fraction of cigarette smoke without the vapor phase, has mostly been tested in short-term in vitro studies lasting from a few hours to a few days. Here, we assessed the toxicity of CSCs from 2 reference cigarettes, 3R4F and CM6, using a primary human small airway epithelial (PSAE) cell line by quantifying adenosine 5'-triphosphate (ATP), 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS), total glutathione (reduced glutathione [GSH] + oxidized glutathione [GSSG]), and lactate dehydrogenase (LDH) release over the course of 28 days. The CSCs, 0.3 to 10 μg/mL, promoted cell proliferation at 120 hours of exposure, but demonstrated cytotoxicity at days 14 and 28. Interestingly, CSCs, 0.3 to 3 μg/mL, showed a cell death effect at day 14 but induced cell proliferation at day 28. Consistently, transformation associated with morphological changes began by day 14 and the transformed cells grew dramatically at day 28. The LDH assay appeared to be sensitive for assessing early cell damage, whereas the ATP, MTS, and GSH assays were more suitable for determining later stage CSCs-induced cytotoxicity. The ATP assay showed greater sensitivity than the MTS and GSH assays. We also assessed the toxicity of CSCs in an human Telomerase Reverse Transcriptase (hTERT)-immortalized Barrett esophagus cell line (CP-C). The CP-C cells demonstrated dose- and time-dependent cytotoxicity over the course of 28 days but displayed higher resistance to CSCs than PSAE cells. This study demonstrates that CSCs cause cytotoxicity and induce transformation related to cell resistance and cell invasion properties.

Introduction: oxidation and inflammation, a molecular link between non-communicable diseases

Non-communicable diseases are, by definition, those chronic diseases that are non-infectious and non-transmissible. The most common non-communicable diseases are obesity, diabetes, cancer, and cardiovascular, chronic respiratory and neurological diseases. Altogether, they are the commonest cause of death and disability in modern world. Recent investigations show that many of these diseases share common pathophysiological mechanisms and are, at least in part, different manifestations in different organs of similar molecular alterations. Mitochondrial alterations, oxidative stress and inflammation are inextricably linked and play major roles in the onset and development of non-communicable diseases. Therefore, it is conceivable that pharmacological or nutritional manipulation of oxidation and inflammation allows a significant decrease in the mortality and morbility associated to these diseases.

Biomarkers of tobacco smoke exposure

Diseases and death caused by exposure to tobacco smoke have become the single most serious preventable public health concern. Thus, biomarkers that can monitor tobacco exposure and health effects can play a critical role in tobacco product regulation and public health policy. Biomarkers of exposure to tobacco toxicants are well established and have been used in population studies to establish public policy regarding exposure to second-hand smoke, an example being the nicotine metabolite cotinine, which can be measured in urine. Biomarkers of biological response to tobacco smoking range from those indicative of inflammation to mRNA and microRNA patterns related to tobacco use and/or disease state. Biomarkers identifying individuals with an increased risk for a pathological response to tobacco have also been described. The challenge for any novel technology or biomarker is its translation to clinical and/or regulatory application, a process that requires first technical validation of the assay and then careful consideration of the context the biomarker assay may be used in the regulatory setting. Nonetheless, the current efforts to investigate new biomarker of tobacco smoke exposure promise to offer powerful new tools in addressing the health hazards of tobacco product use. This review will examine such biomarkers, albeit with a focus on those related to cigarette smoking.

A cross-sectional analysis of candidate biomarkers of biological effect in smokers, never-smokers and ex-smokers

CONTEXT

Biomarkers of biological effect (BOBE) have been proposed as potential tools to assess tobacco product use, toxicity and disease risk.

OBJECTIVE

To determine if candidate BOBE can distinguish between smokers, never-smokers and former smokers.

METHODS

Biomarker levels were compared from 143 smokers, 61 never-smokers and 61 ex-smokers.

RESULTS

In total, 27 candidate biomarkers were assessed, 14 were significantly different between smokers and never-smokers (p < 0.01) and of these 14 biomarkers, 12 were able to distinguish between smokers and former smokers (p < 0.05), which indicates the potential for reversibility.

CONCLUSIONS

A total of 12 of 27 BOBE are potentially useful tools for future product assessment.