Correlation between the Urine Profile of 4-(Methylnitrosamino)-1-(3-Pyridyl)-1-Butanone Metabolites and N7-Methylguanine in Urothelial Carcinoma Patients

Relationships among cigarette smoking, urinary biomarkers, and urothelial carcinoma risk: a case-control study

Cigarette smoke is a known risk factor for urothelial carcinoma (UC). However, there is limited information about the distributions and effects of volatile organic compounds (VOCs) on smoking-related UC risk. With this hospital-based case-control study, we explored the associations between urinary levels of cotinine and VOC metabolites (acrylamide, 1,3-butadiene, and benzene) and the risk of UC. Urological examinations and pathological verifications were used to confirm the diagnoses of UC. All study participants provided smoking-related information via questionnaires and face-to-face interviews; they also provided urine samples for the measurement of VOC metabolites, cotinine, and 8-hydroxydeoxyguanosine (8-OHdG), which was used as an indicator of oxidative stress. We applied multiple logistic regression analysis to estimate the risk of UC, and we found that levels of urinary cotinine and 8-OHdG were higher in the UC group than in the control group. Furthermore, urinary levels of VOC metabolites, including N-acetyl-S-(2-carbamoylethyl)-L-cysteine (AAMA), N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine, N-acetyl-S-(4-hydroxy-2-buten-1-yl)-L-cysteine-3, trans,trans-muconic acid (t,t-MA), and S-phenylmercapturic acid (SPMA), increased with increasing levels of urinary cotinine. After adjusting for potential risk factors, dose-response relationships were observed between UC risk and urinary levels of AAMA, t,t-MA, SPMA, and 8-OHdG. Participants with high urinary levels of cotinine, AAMA, t,t-MA, SPMA, and 8-OHdG had risks of UC that were 3.5- to 6-fold higher than those of participants with lower levels. Future, large-scale investigations of the risks of UC should be explored, and repeated measurement of VOC metabolites should be assessed.

Effects of smoking cessation on biological monitoring markers in urine

INTRODUCTION

Urinary nicotine and cotinine levels are often measured as biomarkers for tobacco smoke exposure. However, these biomarkers are not appropriate to evaluate the effects of quitting smoking for several days, because of their short half-lives. In this study, we focused on the changes in the urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) levels of 55 patients in a smoking cessation program, because of the long half-life. At the same time, urinary 7-methylguanine (m7Gua) and 8-hydroxy-2'-deoxyguanosine (8-OHdG), as DNA damage markers of cigarette smoking, were also measured.

RESULTS

In the subjects who completed the quit-smoking program (18 subjects out of 55), the urinary nicotine and cotinine levels decreased to 1.7 and 0.2% at 8 weeks after the first visit to the clinic. By contrast, the NNAL levels decreased to 12.3% at 8 weeks after quitting smoking. During the same period, the urinary m7Gua levels significantly decreased, from 27.32 μg/mg creatinine to 14.17 μg/mg creatinine by the elimination of subjects who showed increased levels of NNAL during the smoking cessation program. The 8-OHdG levels were also reduced within the same period, but were not significantly different. From the all data analysis, the urinary levels of cotinine and NNAL positively correlated with the level of m7Gua.

CONCLUSIONS

NNAL may be an appropriate exposure marker for evaluating the smoking status of patients in a smoking cessation program. The urinary cotinine and NNAL levels positively correlated with the m7Gua levels.

Guanine-guided time-resolved luminescence recognition of DNA modification and i-motif formation by a terbium(III)-platinum(II) complex

Site-specific recognition of DNA modification or the formation of noncanonical structures has important applications in molecular biology, disease diagnosis, and gene expression analysis. In this study, we introduce a guanine-guided sensing tool using a terbium(III)-platinum(II) complex (TPC) as a time-resolved luminescence probe to site-specifically recognize DNA modification and i-motif formation in aqueous solution. The probe is composed of a Tb^III center as the luminescent reporter and two Pt^II units as the receptor for guanine (G) nucleobase. TPC exhibits remarkable reaction selectivity for guanine nucleotides over other nucleotides, giving rise to a significant increase in luminescence. The luminescence enhancement of TPC is mainly attributed to an energy transfer from G base to the Tb^III center after the specific coordination of Pt^II with N7 of guanine (N7-G), which would be facilitated by the phosphates through promoting the departure of coordinated water and bringing G closer to Tb^IIIvia noncovalent interactions. Based on such sensing feature, the enhanced luminescence of TPC sensitized by G nucleotides can correspondingly decrease upon N7-G modifications of DNA or i-motif formation through constructing simple guanine-guided sensing tools. This probe would provide a useful strategy for site-specific recognition of DNA for extensive purposes.

MicroRNAs in Smoking-Related Carcinogenesis: Biomarkers, Functions, and Therapy

Long-term heavy cigarette smoking is a well-known high-risk factor for carcinogenesis in various organs such as the head and neck, lungs, and urinary bladder. Furthermore, cigarette smoking can systemically accelerate aging, and as the result, promoting carcinogenesis via changing the host microenvironment. Various inflammatory factors, hormones, and chemical mediators induced by smoking mediate carcinoma-related molecules and induce carcinogenesis. MicroRNAs (miRNAs) are a family of short noncoding RNA molecules that bind to mRNAs and inhibit their expression. Cigarette smoke induces the expression of various miRNAs, many of which are known to function in the post-transcriptional silencing of anticancer molecules, thereby leading to smoking-induced carcinogenesis. Analysis of expression profiles of smoking-induced miRNAs can help identify biomarkers for the diagnosis and prognosis of smoking-related cancers and prediction of therapeutic responses, as well as revealing promising therapeutic targets. Here, we introduce the most recent and useful findings of miRNA analyses focused on lung cancer and urinary bladder cancer, which are strongly associated with cigarette smoking, and discuss the utility of miRNAs as clinical biomarkers.

Exposure to fine particulate matter causes oxidative and methylated DNA damage in young adults: A longitudinal study

An increased understanding is needed of the physiological effects and plausible biological mechanisms that link PM_2.5 (particulate matter with an aerodynamic diameter below 2.5μm) exposure to mortality and morbidities such as atherosclerosis and respiratory disease. PM_2.5 causes carcinogenic health effects. Biomonitoring in humans has suggested that 8-oxo-7, 8-dihydro-2-deoxyguanosine (8-oxodG) and N7-methylguanine (N7-MeG) are correlated with oxidative and methylated DNA damage. Thus, it is meaningful to explore the mechanisms of mutagenesis and carcinogenesis associated with oxidative and methylated DNA damage by simultaneously measuring these two markers. We recruited 72 participants from 2 areas (residential and commercial as well as residential and industrial) in the greater Taipei metropolitan area at baseline. Personal samplers were used to collect 24-hour PM_2.5-integrated samples. All participants completed an interview, and blood and urine samples were collected the next morning. All collection procedures were repeated twice after a two-month follow-up period. Urinary 8-oxodG and N7-MeG were assayed as biomarkers of oxidative and methylated DNA damage, respectively. Plasma superoxide dismutase (SOD) and glutathione peroxidase-1 (GPX-1) were measured as biomarkers of antioxidants. Urinary 1-hydroxypyrene (1-OHP) was used as a biomarker of exposure to polycyclic aromatic hydrocarbons (PAHs). The mean PM_2.5 level was 37.3μg/m³ at baseline. PM_2.5 concentrations were higher during winter than during spring and summer. After adjusting for confounds through a generalized estimating equation (GEE) analysis, N7-MeG was significantly increased by 8.1% (β=0.034, 95% CIs=0.001-0.068) per 10μg/m³ increment in PM_2.5. 8-oxodG levels were positively correlated with N7-MeG according to both cross-sectional and longitudinal analyses, and 1-OHP was significantly associated with increasing 8-oxodG and N7-MeG concentrations. Exposure to PM_2.5 increases methylated DNA damage. The mean level of urinary N7-MeG was 1000-fold higher than that of 8-oxodG.

Potential biomarkers for monitoring the toxicity of long-term exposure to atrazine in rat by metabonomic analysis

1. Herbicide atrazine (ATR) poses harmful effects on human health. The purpose of this study is to study potential biomarkers used for monitoring the toxic effects after chronic exposure to ATR by studying urine metabolites. 2. Rats were assigned into clinical chemistry and metabonomics arms, and each arm was divided into low-dose, high-dose and control groups. ATR was administered to rats along with their feed. At the end of 16, 20 and 24 weeks, clinical parameters and histopathologic changes was assessed to monitor the toxic effects. Twenty-four hour urine samples was analyzed by UPLC-MS, to find the significant alterations in metabolic profiling. 3. The body weight of rats in ATR group was lower than that of control starting from 12th week; abnormal levels of serum biochemistry and histopathologic alterations of organs were found initially from 16th and 20th week, respectively. Five exogenous and five endogenous metabolites were found which showed significant differences between ATR groups and control group at above-mentioned time points. 4. These metabolites may be used as potential indicators to monitor ATR toxicity, and also may provide some clues for understanding the mechanism of toxicity of ATR. The exact relationship between endogenous metabolites and ATR toxicity needs further investigation.

A correlation study applied to biomarkers of internal and effective dose for acrylonitrile and 4-aminobiphenyl in smokers

The urinary metabolites 2-cyanoethylmercapturic acid and 4-aminobiphenyl have been correlated with tobacco smoke exposure. Similarly, 2-cyanoethylvaline and 4-aminobiphenyl haemoglobin adducts have been used as biomarkers of effective dose for the exposure to acrylonitrile and 4-aminobiphenyl, respectively. Each pair of biomarkers is derived from the same parent chemical; however, the correlation between the urinary and the haemoglobin biomarkers has not been investigated. Using clinical study samples, we report a weak correlation between urinary and haemoglobin biomarkers due to different accumulation and elimination rates. Time course analysis showed that a reduction in exposure was paralleled by a delayed reduction in haemoglobin adducts.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism-related enzymes gene polymorphisms, NNK metabolites levels and urothelial carcinoma

Gene polymorphisms of the 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) metabolism-related enzymes-cytochrome P450 (CYP) monooxygenase 2A13 (CYP2A13) and UDP-glucuronosyltransferases (UGT)-2B7 could contribute to the levels of NNK-related metabolites in urine, thereby increasing the susceptibility to urothelial carcinoma (UC). Therefore, our study aimed to evaluate the roles of two gene polymorphisms (CYP2A13 and UGT2B7) of NNK metabolism-related enzymes in the carcinogenesis of UC in Taiwan. A hospital-based pilot case-control study was conducted. There were 121 UC cases and 121 age- and sex-matched healthy participants recruited from March 2007 to April 2009. Urine samples were analyzed for NNK-related metabolites using the liquid chromatography-tandem mass spectrometry method. Genotyping was conducted using a polymerase chain reaction-restriction fragment length polymorphism technique. ANCOVA and multivariate logistic regression were applied for data analyses. In healthy controls, former smokers had significantly higher total NNAL and higher NNAL-Gluc than never smokers or current smokers. Subjects carrying the UGT2B7 268 His/Tyr or Tyr/Tyr genotype had significantly lower total NNAL than those carrying His/His genotype. However, no association was seen between gene polymorphisms of CYP2A13 and UGT2B7 and UC risk after adjustment for age and sex. Significant dose -response associations between total NNAL, free NNAL, the ratios of free NNAL/total NNAL and NNAL-Gluc/total NNAL and UC risk were observed. In the future, large-scale studies will be required to verify the association between the single nucleotide polymorphisms of NNK metabolism-related enzymes and UC risk.

4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone is correlated with 8-hydroxy-2'-deoxyguanosine in humans after exposure to environmental tobacco smoke

Cigarette smoking and exposure to environmental tobacco smoke (ETS) are important risk factors for many cancers. However, exposure doses have usually not been quantitatively assessed in human studies. In humans 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and its glucuronate conjugate (defined as total NNAL) are the major metabolites of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone, a cigarette-specific carcinogen. Although animal studies have shown that exposure to cigarette smoke increases tissue oxidative DNA damage, the relationship between cigarette smoke and 8-hydroxydeoxyguanosine (8-OHdG) is not consistent in human studies. In the present study, we have developed a simple, sensitive, and robust LC-MS/MS method for quantifying total NNAL and 8-OHdG concentrations in human plasma. We quantified total NNAL and 8-OHdG in plasma as well as 8-OHdG in urine of 121 healthy male subjects. Total NNAL levels were significantly higher in ever-smokers than in never-smokers. Furthermore, total NNAL levels in plasma were increased with numbers of cigarettes smoked per day in ever-smokers. It suggests that total NNAL in plasma is a good biomarker for cigarette smoke exposure. After stratifying by smoking status and adjusting for age, ETS exposure and occupation category, total NNAL was associated with plasma and urinary 8-OHdG in never-smokers, but not in ever-smokers. Since total NNAL levels in nonsmokers represented the ETS exposure, it appears that 8-OHdG levels are dose-dependently correlated with their ETS exposure dose. Furthermore, this correlation supports the hypothesis that oxidative DNA damage is one of major adverse effects induced by ETS exposure in humans.

Synergism between 2,3,7,8-tetrachlorodibenzo-p-dioxin and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone on lung tumor incidence in mice

Although 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is classified as a human carcinogen, TCDD only induced oxidative DNA damages. In our present study, we combined TCDD with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) to investigate their tumorigenic effects on lung tumor formation in A/J mice. Application of NNK at a tumorigenic dose (2 mg/mouse) induced lung adenoma in both male and female A/J mice. Neither application of NNK at a non-tumorigenic dose (1 mg/mouse) nor repeated application of TCDD alone increased tumor incidence. Following the single injection of NNK at a non-tumorigenic dose (1 mg/mouse), repeated application of TCDD significantly increased the lung tumor incidence in female, but not in male, A/J mice 24 weeks later. Utilizing the real-time RT-PCR array, we found that P16 mRNA was significantly reduced in female lung, but not male lung, of NNK/TCDD co-treated A/J mice. With immunohistochemical staining, we confirmed that nuclear P16 protein was reduced in the lungs of NNK/TCDD co-treated female mice. These data suggest that P16 reduction at least partially contributed to synergistic effects of TCDD in lung tumorigenesis.