Relationship between urinary 15-F2t-isoprostane and 8-oxodeoxyguanosine levels and breast cancer risk

Associations of the Paleolithic Diet Pattern Scores and the Risk of Breast Cancer among Adults: A Case-Control Study

Evidence suggests the role of changing traditional lifestyle patterns such as Paleolithic to modern lifestyle in the incidence and epidemic of chronic diseases. Thus, this study aimed to investigate the association between Paleolithic diet (PD) and risk of Breast Cancer (BC) in adult Iranian women. This matched case-control study included 253 women with BC and 267 healthy women aged >18 years. PD score was evaluated using a validated 168-item quantitative food frequency questionnaire. Conditional logistic regression model was used to estimate odds ratios (ORs) and 95% confidence intervals (95%CIs), and dose-response was investigated. Mean of PD score was 39.00 ± 6.39. Among the food groups of the PD components, BC patients significantly had lower consumption of healthy food groups as vegetables, fruits, fish, and nuts, higher intakes of sugar-sweetened beverages as well as grains and starches. After adjustment for potential confounders, comparing the highest quartile of PD scores with the lowest quartile, a decrease in the risk of BC was observed for all women (OR: 0.26; 95% CI: 0.13-0.53), as well as those premenopausal (OR: 0.29; 95% CI: 0.11), and postmenopausal (OR: 0.17; 95% CI: 0.05 - 0.56). Our findings show that adherence to the PD pattern significantly reduces the risk of BC in the population studied. However, prospective studies are needed to further investigate this association.

Oxidative Stress and Menopausal Status: The Coronary Artery Risk Development in Young Adults Cohort Study

Background: Low endogenous estrogen concentrations after menopause may contribute to higher oxidative stress and greater cardiovascular disease (CVD) risk. However, differences in oxidative stress between similarly aged premenopausal and postmenopausal women are not well-characterized on a population level. We hypothesized that urinary isoprostane concentrations, a standard measure of systemic oxidative stress, are higher in women who have undergone menopause compared to premenopausal women. Methods and Results: We examined differences in urinary 8-isoprostane (iPF_2α-III) and 2,3-dinor-8-isoprostane (iPF_2α-III-M) indexed to urinary creatinine between 279 postmenopausal and 196 premenopausal women in the Coronary Artery Risk Development in Young Adults (CARDIA) study, using linear regression with progressive adjustment for sociodemographic factors and traditional CVD risk factors. Unadjusted iPF_2α-III-M concentrations were higher among postmenopausal compared to premenopausal women (Median [25th, 75th percentile]: 1762 [1178, 2974] vs. 1535 [1067, 2462] ng/g creatinine; p = 0.01). Menopause was associated with 25.5% higher iPF_2α-III-M (95% confidence interval [6.5-47.9]) adjusted for age, race, college education, and field center. Further adjustments for tobacco use (21.2% [2.9-42.6]) and then CVD risk factors (18.8% [0.1-39.6]) led to additional partial attenuation. Menopause was associated with higher iPF_2α-III in Black but not White women. Conclusions: We conclude that postmenopausal women had higher oxidative stress, which may contribute to greater CVD risk. ClinicalTrials.gov Identifier: NCT00005130.

Prediagnostic Levels of Copper and Zinc and Breast Cancer Risk in the ORDET Cohort

BACKGROUND

Case-control studies show that copper (Cu) is high and zinc (Zn) low in blood and urine of women with breast cancer compared with controls.

METHODS

To assess whether prediagnostic Cu and Zn are associated with breast cancer risk, OR of breast cancer according to Cu, Zn, and Cu/Zn ratio in plasma and urine was estimated in a nested case-control study within the ORDET cohort, using conditional logistic regression adjusted for multiple variables: First 496 breast cancer cases and matched controls, diagnosed ≥2 years after recruitment (to eliminate reverse causation) were analyzed. Then all eligible cases/controls were analyzed with stratification into years from recruitment to diagnosis.

RESULTS

For women diagnosed ≥2 years, compared with lowest tertiles, breast cancer risk was higher in the highest tertile of plasma Cu/Zn ratio (OR, 1.75; 95% CI, 1.21-2.54) and the highest tertile of both plasma and urine Cu/Zn ratio (OR, 2.37; 95% CI, 1.32-4.25). Risk did not vary with ER/PR/HER2 status. For women diagnosed <2 years, high Cu/Zn ratio was strongly associated with breast cancer risk.

CONCLUSIONS

Our prospective findings suggest that increased Cu/Zn ratio in plasma and urine may be both an early marker of, and a risk factor for, breast cancer development. Further studies are justified to confirm or otherwise our results and to investigate mechanisms.

IMPACT

Our finding that prediagnostic Cu/Zn ratio is a strong risk factor for breast cancer development deserves further investigation and, if confirmed, might open the way to interventions to reduce breast cancer risk in women with disrupted Cu/Zn homeostasis.

Correlation between biomarkers of exposure, effect and potential harm in the urine of electronic cigarette users

Objectives

To determine if urinary biomarkers of effect and potential harm are elevated in electronic cigarette users compared with non-smokers and if elevation correlates with increased concentrations of metals in urine.

Study design and setting

This was a cross-sectional study of biomarkers of exposure, effect and potential harm in urine from non-smokers (n=20), electronic cigarette users (n=20) and cigarette smokers (n=13). Participant’s screening and urine collection were performed at the Roswell Park Comprehensive Cancer Center, and biomarker analysis and metal analysis were performed at the University of California, Riverside.

Results

Metallothionein was significantly elevated in the electronic cigarette group (3761±3932 pg/mg) compared with the non-smokers (1129±1294 pg/mg, p=0.05). 8-OHdG (8-hydroxy-2′-deoxyguanosine) was significantly elevated in electronic cigarette users (442.8±300.7 ng/mg) versus non-smokers (221.6±157.8 ng/mg, p=0.01). 8-Isoprostane showed a significant increase in electronic cigarette users (750.8±433 pg/mg) versus non-smokers (411.2±287.4 pg/mg, p=0.03). Linear regression analysis in the electronic cigarette group showed a significant correlation between cotinine and total metal concentration; total metal concentration and metallothionein; cotinine and oxidative DNA damage; and total metal concentration and oxidative DNA damage. Zinc was significantly elevated in the electronic cigarette users (584.5±826.6 µg/g) compared with non-smokers (413.6±233.7 µg/g, p=0.03). Linear regression analysis showed a significant correlation between urinary zinc concentration and 8-OHdG in the electronic cigarette users.

Conclusions

This study is the first to investigate biomarkers of potential harm and effect in electronic cigarette users and to show a linkage to metal exposure. The biomarker levels in electronic cigarette users were similar to (and not lower than) cigarette smokers. In electronic cigarette users, there was a link to elevated total metal exposure and oxidative DNA damage. Specifically, our results demonstrate that zinc concentration was correlated to oxidative DNA damage.

Impact of Physical Activity on Oxidative Stress Markers in Patients with Metastatic Breast Cancer

Purpose

Regular physical activity (PA) can affect oxidative stress, known to be involved in carcinogenesis. The objective of this study was to evaluate the associations between a six-month PA intervention and oxidative stress biomarkers, PA, and clinical outcomes in patients with metastatic breast cancer.

Methods

Forty-nine newly diagnosed patients with metastatic breast cancer were recruited for a single-arm, unsupervised, and personalized six-month walking intervention with activity tracker. PA level and PA fitness, plasma concentrations of DNA oxidation (8OhdG), lipid peroxidation (MDA), and protein oxidation (AOPP), plasma activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase, plasma and leucocyte activities of myeloperoxidase (MPO) and NADPH oxidase (NOX), and clinical markers of tumor progression (RECIST criteria) were measured at baseline and after the six-month intervention.

Results

GPX activity (+17%) and MDA (+9%) significantly increased between baseline and the end of the intervention. Changes in PA level and fitness were significantly positively correlated with changes in plasma GPX and significantly negatively with changes in NOX in the leucocytes. Plasma MDA was significantly higher (+20%) whereas plasma AOPP was lower (-46%) for patients with tumor progression or that died during the six months as compared to patients without progression.

Conclusion

A six-month PA intervention may be potentially beneficial in metastatic breast cancer patients for enhancing antioxidant enzyme activity and decreasing prooxidant enzyme activity. Moreover, AOPP and MDA could also be favorable and unfavorable biomarkers, respectively, since they are associated with disease progression and fitness level in this population. This trial is registered with NCT number: NCT03148886.

Cyclopentenone Prostaglandins: Biologically Active Lipid Mediators Targeting Inflammation

Cyclopentenone prostaglandins (cyPGs) are biologically active lipid mediators, including PGA2, PGA1, PGJ2, and its metabolites. cyPGs are essential regulators of inflammation, cell proliferation, apoptosis, angiogenesis, cell migration, and stem cell activity. cyPGs biologically act on multiple cellular targets, including transcription factors and signal transduction pathways. cyPGs regulate the inflammatory response by interfering with NF-κB, AP-1, MAPK, and JAK/STAT signaling pathways via both a group of nuclear receptor peroxisome proliferator-activated receptor-gamma (PPAR-γ) dependent and PPAR-γ independent mechanisms. cyPGs promote the resolution of chronic inflammation associated with cancers and pathogen (bacterial, viral, and parasitic) infection. cyPGs exhibit potent effects on viral infections by repressing viral protein synthesis, altering viral protein glycosylation, inhibiting virus transmission, and reducing virus-induced inflammation. We summarize their anti-proliferative, pro-apoptotic, cytoprotective, antioxidant, anti-angiogenic, anti-inflammatory, pro-resolution, and anti-metastatic potential. These properties render them unique therapeutic value, especially in resolving inflammation and could be used in adjunct with other existing therapies. We also discuss other α, β -unsaturated carbonyl lipids and cyPGs like isoprostanes (IsoPs) compounds.

Effects of neoadjuvant therapies on genetic regulation of targeted pathways in ER+ primary ductal breast carcinoma: A meta-analysis of microarray datasets

Breast cancer arises as a result of multiple interactions between environmental and genetic factors. Conventionally, breast cancer is treated based on histopathological and clinical features. DNA technologies like the human genome microarray are now partially integrated into clinical practice and are used for developing new "personalized medicines" and "pharmacogenetics" for improving the efficiency and safety of cancer medications. We investigated the effects of four established therapies-for ER+ ductal breast cancer-on the differential gene expression. The therapies included single agent tamoxifen, two-agent docetaxel and capecitabine, or combined three-agents CAF (cyclophosphamide, doxorubicin, and fluorouracil) and CMF (cyclophosphamide, methotrexate, and fluorouracil). Genevestigator 8.1.0 was used to compare five datasets from patients with infiltrating ductal carcinoma, untreated or treated with selected drugs, to those from the healthy control. We identified 74 differentially expressed genes involved in three pathways, i.e., apoptosis (extrinsic and intrinsic), oxidative signaling, and PI3K/Akt signaling. The treatments affected the expression of apoptotic genes (TNFRSF10B [TRAIL], FAS, CASP3/6/7/8, PMAIP1 [NOXA], BNIP3L, BNIP3, BCL2A1, and BCL2), the oxidative stress-related genes (NOX4, XDH, MAOA, GSR, GPX3, and SOD3), and the PI3K/Akt pathway gene (ERBB2 [HER2]). Breast cancer treatments are complex with varying drug responses and efficacy among patients. This necessitates identifying novel biomarkers for predicting the drug response, using available data and new technologies. GSR, NOX4, CASP3, and ERBB2 are potential biomarkers for predicting the treatment response in primary ER+ ductal breast carcinoma.

Redox changes in obesity, metabolic syndrome, and diabetes

"Life is an instantaneous encounter of circulating matter and flowing energy" (Jean Giaja, Serbian physiologist), is one of the most elegant definitions not only of life but the relationship of redox biology and metabolism. Their evolutionary liaison has created inseparable yet dynamic homeostasis in health, which, when disrupted, leads to disease. This interconnection is even more pertinent today, in an era of increasing metabolic diseases of epidemic proportions such as obesity, metabolic syndrome, and diabetes. Despite great advances in understanding the molecular mechanisms of redox and metabolic regulation, we face significant challenges in preventing, diagnosing, and treating metabolic diseases. The etiological association and temporal overlap of these syndromes present significant challenges for the discrimination of appropriate clinical biomarkers for diagnosis, treatment, and outcome prediction. These multifactorial, multiorgan metabolic syndromes with complex etiopathogenic mechanisms are accompanied by disturbed redox equilibrium in target tissues and circulation. Free radicals and reactive species are considered both a causal factor and a consequence of disease status. Thus, determining the subtypes and levels of free radicals and reactive species, oxidatively damaged biomolecules (lipids, proteins, and nucleic acids) and antioxidant defense components as well as redox-sensitive transcription factors and fluxes of redox-dependent metabolic pathways will help define existing and establish novel redox biomarkers for stratifying metabolic diseases. This review aims to discuss diverse redox/metabolic aspects in obesity, metabolic syndrome, and diabetes, with the imperative to help establish a platform for emerging and future redox-metabolic biomarkers research in precision medicine. Future research warrants detailed investigations into the status of redox biomarkers in healthy subjects and patients, including the use of emerging 'omic' profiling technologies (e.g., redox proteomes, lipidomes, metabolomes, and transcriptomes), taking into account the influence of lifestyle (diet, physical activity, sleep, work patterns) as well as circadian ~24h fluctuations in circulatory factors and metabolites.

Hubungan Asupan dan Kadar Serum β-karoten, Aktivitas SOD, TNF-α dan 8-isoprostan serum dengan Ukuran Tumor Payudara

Latar Belakang: Kanker payudara dapat disebabkan oleh berkembangnya Reactive Oxygen Species (ROS) di dalam sel yang memicu stres oksidatif dan oksidasi pada DNA. DNA akan kehilangan kemampuannya untuk memperbaiki diri dan terjadi mutasi. Mutasi dapat menyebabkan pertumbuhan dan perkembangan sel tumor. Asupan antioksidan seperti β-karoten pada penderita tumor dimungkinkan dapat menurunkan stres oksidatif dan risiko berkembangnya kanker.Tujuan: Penelitian ini bertujuan untuk menganalisis hubungan asupan dan kadar serum β-karoten, aktivitas SOD, TNF-α dan 8-isoprostan serum dengan ukuran tumor payudara.Metode: Penelitian ini menggunakan desain cross-sectional. Data yang digunakan adalah data baseline dari penelitian utama yang diambil pada bulan November-Desember 2018. Sebanyak 15 orang wanita yang terindikasi tumor payudara dan memenuhi kriteria inklusi serta eksklusi diikutsertakan dalam penelitian ini. Data dianalisis menggunakan uji korelasi Pearson dan spearman.Hasil: Usia subjek berkisar antara 22-52 tahun dengan rata-rata usia 36 tahun. Hasil penelitian menunjukkan asupan β-karoten per hari masih kurang. Terdapat hubungan antara asupan β-karoten dengan aktivitas SOD (p=0,025; r=0,408) dan aktivitas SOD dengan ukuran tumor payudara (p=0,018; r=-0,430). Hal ini menunjukkan bahwa terdapat hubungan tidak langsung antara asupan β-karoten dengan ukuran tumor payudara. Kadar serum β-karoten, TNF-α dan 8-isoprostan serum tidak berhubungan signifikan dengan ukuran tumor payudara (p=0,107; r=-0,430 | p=0.061; r=0,347 | p= 0,217; r=0,232).Kesimpulan: Terdapat hubungan antara asupan β-karoten dengan aktivitas SOD dan aktivitas SOD dengan ukuran tumor payudara.

Oxidative stress induction in woodworkers occupationally exposed to wood dust and formaldehyde

BACKGROUND

Many workers are exposed to wood dust (WD) and formaldehyde (FA), whose carcinogenic activity is supposed to be oxidative stress-mediated. This study aims to assess to what extent the occupational exposure to WD and FA, albeit within regulatory limits, could result in OS induction in a woodworkers' population.

METHODS

The sample population consisted of 127 woodworkers from 4 factories and 111 unexposed controls. Individual exposure was assessed by personal air-samplers. Each participant enrolled in the study filled out a questionnaire and provided a urinary sample to quantify OS biomarkers, namely 15-F2t-IsoProstane (15-F2t-IsoP) and 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-dGuo). The main confounding factor for OS, i.e. tobacco smoking exposure, was assessed by measuring cotinine in urine samples.

RESULTS

Woodworkers were exposed to significantly higher amounts of WD and FA as compared to controls (p < 0.001). Among OS biomarkers, 15-F2t-IsoP showed statistically significant higher values in woodworkers compared to controls (p = 0.004). A significant, positive correlation was observed between 15-F2t-IsoP and 8-oxo-dGuo (p = 0.005), cotinine (p = 0.05), FA (p < 0.001) and WD (p = 0.01); 8-oxo-dGuo was significantly correlated with cotinine (p = 0.001) and WD (p = 0.004). In addition, WD and FA were significantly correlated each other (p < 0.001).

CONCLUSIONS

The study confirms that WD and FA may induce OS in woodworkers, and highlights that even the compliance with occupational exposure limits can result in measurable biological outcomes.

Evaluation of the Diagnostic and Predicative Values of 8-Iso-Prostaglandin F2α as a Biomarker of Breast Cancer

BACKGROUND

Breast cancer (BC) is a commonly reported cancer that is widely prevalent among women. Its early detection improves patient survival and results in better outcomes. For diagnosis and follow-up care, tumor markers are one of the feasible investigations to be ordered. 8-Iso-prostaglandin F2α (8-iso-PGF2α) serves as a serum marker reflecting oxidative stress and subsequent damaging of DNA. In the present study, we aimed to evaluate both diagnostic and predictive values of 8-iso-PGF2α in BC patients.

MATERIALS AND METHODS

Serum levels of 8-iso-PGF2α were assessed for 66 women with benign breast tumors and 65 women who had malignant BC. To compare the patients who had breast tumors with healthy individuals, 63 women free of breast diseases were selected as controls.

RESULTS

The serum level of 8-iso-PGF2α in the BC patients (57.92 pg/mL) was significantly higher compared to those with benign tumors (18.89 pg/mL) (p < 0.001). In addition, individuals with no breast diseases had less 8-iso-PGF2α (4.02 pg/mL) compared to those who had developed a tumor (p < 0.001). Serum 8-iso-PGF2α was found to be positively correlated with both carcinoembryonic antigen (r = 0.74, p < 0.001) and cancer antigen 15-3 (r = 0.80, p < 0.001). Furthermore, serum 8-iso-PGF2α showed high diagnostic performance in BC (AUC = 0.999, sensitivity = 100%, specificity = 99.2% at a cutoff value of 36.18 pg/mL).

CONCLUSIONS

Our study found that the high level of serum 8-iso-PGF2α helps to provide a non-invasive indicator to detect BC. Future work with a larger sample size and various phases of BC can confirm the current results which provide insights into the early detection of cancer.

Influence of pubertal development on urinary oxidative stress biomarkers in adolescent girls in the New York LEGACY cohort

Puberty is a time of intense growth and differentiation of breast tissue and a window of susceptibility (WOS) for breast cancer. Although oxidative stress markers have been associated with breast cancer risk, it is unclear whether oxidative stress levels are different during the pubertal WOS, and if so, whether these differences are related to breast cancer susceptibility. We measured urinary biomarkers of whole body oxidative stress (urinary F2-Isoprostanes and 8-oxodeoxyguanosine (8-oxodG)) in 158 girls (ages 6-13 years), 71 with and 87 without a breast cancer family history (BCFH) from a cohort of adolescent girls from the New York site of the LEGACY cohort (Lessons in Epidemiology and Genetics in Adults Cancer from Youth). We compared levels of urinary oxidative stress biomarkers (F2-Isoprostanes and 8-oxodG) across the pubertal window, defined by Tanner Stage (TS) of breast development, both cross-sectionally and longitudinally within girls over an 18-month follow up period. Urinary oxidative stress biomarkers were unrelated to pubertal stages in cross-sectional analyses after considering adjustments for body mass index (BMI) and BCFH. In our longitudinal analysis, we found that urinary 8-oxodG levels, but not F2-Isoprostane levels, increased with age in BCFH + girls (β = 6.12, 95% CI = 0.08-12.16) compared to BCFH-girls. Higher BMI was associated with higher level of F2-Isoprostane in both cross-sectional (β = 0.02, 95% CI = 0.0004-0.05) and longitudinal analysis (β = 0.02, 95% CI = 0.0002-0.05). These findings support that higher BMI increases oxidative stress biomarkers over the pubertal window and that there are changes in 8-oxodG oxidative stress biomarkers in girls with a BCFH compared to girls without a BCFH.

Airborne mammary carcinogens and breast cancer risk in the Sister Study

INTRODUCTION

Potentially carcinogenic hazardous air pollutants (air toxics) have been inconsistently associated with breast cancer. Whether metabolic factors modify these associations is unknown. We studied 29 non-metallic air toxics classified as mammary gland carcinogens in animal studies in relation to breast cancer risk.

METHODS

Participants included 49,718 women from the Sister Study. Census tract air toxic concentration estimates from the 2005 National Air Toxics Assessment were linked to enrollment residential addresses. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for individual air toxics were estimated using Cox regression. Body mass index (BMI) was considered a potential modifier. Relevant mixtures were identified using classification trees.

RESULTS

Over follow-up (average = 8.4 years), 2975 women were newly diagnosed with breast cancer (invasive or ductal carcinoma in situ). Several air toxics, including methylene chloride, polycyclic organic matter, propylene dichloride, and styrene, were associated with increased risk. Of these, methylene chloride was most consistently associated with risk across multiple analyses. It was associated with overall (HRquintile 4vs1 = 1.21 (95%CI = 1.07-1.38)) and estrogen receptor positive (ER+) invasive breast cancer (HRquintile 4vs1 = 1.28 (95%CI = 1.08-1.52)) in individual pollutant models, although no dose-response was observed. Associations were stronger among overweight/obese (vs. non-overweight/obese) women (p < 0.05) for six air toxics. The classification tree identified combinations of age, methylene chloride, BMI, and four other toxics (propylene dichloride, ethylene dibromide, ethylidene dichloride, styrene) related to overall breast cancer.

CONCLUSIONS

Some non-metallic air toxics, particularly methylene chloride, were associated with the hazard for overall and ER+ breast cancer. Overweight/obese women may be particularly susceptible to air toxics.

Dose-response association of serum alanine aminotransferase levels with multimorbidity

Multimorbidity has posed a major challenge to health care systems worldwide, but little is known about its association with biological factors. This study represents the first one to examine the association of serum levels of alanine aminotransferase (ALT) with multimorbidity. The baseline category logistic regression model was used to estimate the odds ratio (OR) between ALT and multimorbidity, and the area under the receiver operating characteristic curve (AUC) was used to evaluate the classification utility of ALT. Serum ALT levels were associated, in a dose-response manner, with multimorbidity. Compared with the first quartile, the adjusted OR (95% confidence interval) of the fourth quartile for multimorbidity was 4.71 (3.56–6.23). In addition, the AUC value for distinguishing the multimorbidity group from the control group reached 0.7185. In conclusion, high levels of ALT were significantly correlated with multimorbidity and this association was independent of other potential risk factors. Serum ALT might be a useful marker for identifying individuals with multimorbidity.

Tea consumption and oxidative stress: a cross-sectional analysis of 889 premenopausal women from the Sister Study

In experimental and clinical studies, green or black tea consumption has been shown to reduce oxidative stress. However, these studies involved high levels of tea consumption and may not reflect patterns in the general population. Here, we examined the association between black or green tea consumption and oxidative stress in a cross-sectional study of 889 premenopausal US women aged 35-54 years. Tea consumption was measured using the Block-98 FFQ. Urinary 8-iso-PGF2α (F2-IsoP) and 2,3-dinor-5,6-dihydro-15-F2t-isoprostane (15-F2t-IsoP-M) were used as biomarkers of oxidative stress. These compounds were measured by MS and normalised to creatinine. Linear regression was used to calculate the geometric mean differences (GMD) and 95% CI for log-transformed urinary F2-IsoP or 15-F2t-IsoP-M in relation to black or green tea consumption. We further examined whether adjusting for caffeine impacted associations between tea and oxidative stress. Geometric means of urinary F2-IsoP and 15-F2t-IsoP-M were 1·44 (95% CI 1·39, 1·49) and 0·71 (95% CI 0·69, 0·73) ng/mg creatinine, respectively. Overall, green tea consumption was not associated with urinary F2-IsoP or 15-F2t-IsoP-M. High-level black tea consumption (≥5 cups/week compared with 0) was associated with higher 15-F2t-IsoP-M concentrations (adjusted GMD=0·10, 95 % CI 0·02-0.19) but not F2-IsoP. Adjusting for caffeine nullified the association between black tea and 15-F2t-IsoP-M. Our findings do not support the hypothesis that dietary tea consumption is inversely associated with oxidative stress.

Fatty acids: Adiposity and breast cancer chemotherapy, a bad synergy?

Globally, breast cancer continues to be a major concern in women's health. Lifestyle related risk factors, specifically excess adipose tissue (adiposity) has reached epidemic proportions and has been identified as a major risk factor in the development of breast cancer. Dysfunctional adipose tissue has evoked research focusing on its association with metabolic-related conditions, breast cancer risk and progression. Adipose dysfunction in coordination with immune cells and inflammation, are responsible for accelerated cell growth and survival of cancer cells. Recently, evidence also implicates adiposity as a potential risk factor for chemotherapy resistance. Chemotherapeutic agents have been shown to negatively impact adipose tissue. Since adipose tissue is a major storage site for fatty acids, it is not unlikely that these negative effects may disrupt adipose tissue homeostasis. It is therefore argued that fatty acid composition may be altered due to the chemotherapeutic pharmacokinetics, which in turn could have severe health related outcomes. The underlying molecular mechanisms elucidating the effects of fatty acid composition in adiposity-linked drug resistance are still unclear and under explored. This review focuses on the potential role of adiposity in breast cancer and specifically emphasizes the role of fatty acids in cancer progression and treatment resistance.

Pre-diagnostic urinary 15-F2t -isoprostane level and liver cancer risk: Results from the Shanghai Women's and Men's Health Studies

Oxidative stress has been hypothesized to affect cancer development via various mechanisms, but the evidence from human is limited and inconclusive. 15-F_2t -isoprostane (15-F_2t -IsoP) is an accurate marker of oxidative stress in humans. Recent studies showed that the evidence of urinary 15-F_2t -IsoP level correlating cancer risk is conflicting. We conducted a case-control study nested within two population-based cohort studies. Pre-diagnosis urine samples, collected at cohort enrollment, from 363 incident liver cancer cases and 725 individually matched controls, were used to determine the level of 15-F_2t -IsoP by enzyme-linked immunosorbent assay. Conditional logistic regression model was used to estimate the odds ratio to measure the association between the urinary 15-F_2t -IsoP level and liver cancer risk. We found that higher pre-diagnostic urinary 15-F_2t -IsoP level was associated with an increased liver cancer risk, with an adjusted OR in males (OR_{4th vs. 1st quartile}  = 8.84, 95% CI 2.74-28.60), which was significantly higher than those in females (OR_{4th vs. 1st quartile}  = 1.75, 95% CI 0.70-4.42). HBsAg carriers with higher 15-F_2t -IsoP had a significantly increased liver cancer risk (OR_female  = 59.04, 95% CI 12.26, 284.30; OR_male  = 92.55, 95% CI 34.83, 245.96) compared to non-carriers with lower 15-F_2t -IsoP. High urinary 15-F_2t -IsoP level was associated with high liver cancer risk, suggesting that 15-F_2t -IsoP may be a promising biomarker for liver cancer risk. The result suggests that people with sero-positive HBsAg and higher level of 15-F_2t -IsoP might be given a higher priority on future surveillance program of liver cancer.

Urinary 8-isoprostane levels and occurrence of lung, colorectal, prostate, breast and overall cancer: Results from a large, population-based cohort study with 14 years of follow-up

BACKGROUND

Urinary 8-isoprostane is an established biomarker for lipid peroxidation. However, the association between its pre-diagnostic levels and cancer incidence has rarely been evaluated.

METHODS

8793 older adults from the German ESTHER cohort were followed up for cancer incidence by cancer registry data. A directed acyclic graph was utilized to identify potential confounders. Multivariate Cox regression models were applied to estimate hazard ratios (HRs) and 95% confidence intervals (95% CI).

RESULTS

During 14-year follow-up, 1540 incident cancer cases, including 207 lung, 196 colorectal, 218 breast and 245 prostate cancer cases were detected. 8-isoprostane concentrations were positively associated with lung cancer, but not with cancer at the other sites. The HR (95% CI) for the association with lung cancer was 1.61 (1.10, 2.34) for comparison of the top with bottom tertile in total population. The association of 8-isoprostane levels with lung cancer persisted after the adjustment for smoking and other potential confounders and was multiplicative to the effect of smoking. However, 8-isoprostane levels did not improve lung cancer prediction when added to a model containing age, sex and smoking. A protective association of increasing 8-isoprostane levels was observed for prostate cancer incidence but this association was only statistically significant among current smokers.

DISCUSSION

Our findings suggest that lipid peroxidation is involved in the development of lung cancer. However, high oxidative stress may be a protective factor for prostate cancer, especially among current smokers.

Pituitary, Gonadal, Thyroid Hormones and Endocrine Disruptors in Pre and Postmenopausal Nigerian Women with ER-, PR- and HER-2-Positive and Negative Breast Cancers

Breast cancer is broadly sub-divided into hormone responsive and non-hormone responsive subtypes. Estradiol has been associated with hormone responsive breast cancers. There is, however, a paucity of information on the role of sex hormones, gonadotropins, and thyroid hormone in non-hormone responsive breast cancer. This study aimed to determine differences in the serum levels of sex hormones, gonadotropins, thyroid hormones, and endocrine disruptors (lead, cadmium, and arsenic) in Nigerian women with hormone responsive and non-hormone responsive breast cancers. Seventy-nine non-pregnant women aged 28–80 years with histologically confirmed breast cancer were recruited, pre-therapy, into this cross-sectional study. They comprised 52 premenopausal women and 27 postmenopausal women recruited from the Surgical Oncology Clinic of the Department of Surgery, University College Hospital, Ibadan. Comparison of biochemical parameters were based on the positivity (+) and negativity (−) of estrogen receptor (ER), progesterone receptor (PR) and human epithelial receptor-2 (HER-2). Estradiol, progesterone, follicle stimulating hormone (FSH), luteinizing hormone (LH), free thyroxine (FT₄), free triiodothyronine (FT₃), and thyroid stimulating hormone (TSH) were determined using enzyme immunoassay (EIA). Serum lead, cadmium and arsenic were determined using atomic absorption spectrophotometry (AAS). Expression of ER, PR and HER2 were determined using immunohistochemistry. Data was analyzed using Mann-Whitney U-test and multiple regression, with p < 0.05 considered as being statistically significant. Estradiol and progesterone were significantly higher in breast cancer participants with ER⁻ and PR⁻ compared with those with ER⁺ and PR⁺ breast cancer (p < 0.05). Follicle stimulating hormone and LH levels were significantly higher in participants with ER⁺ and PR⁺ breast cancer compared with participants with ER⁻ and PR⁻ breast cancer (p < 0.05). Arsenic was inversely related with TSH in premenopausal participants with ER⁻ and PR⁻ (β = −0.305; β = −0.304, respectively). Sex hormones and gonadotropins appear to be involved in the pathogenesis of triple negative and luminal breast cancer, respectively.

Dietary Weight Loss, Exercise, and Oxidative Stress in Postmenopausal Women: A Randomized Controlled Trial

Oxidative stress, a potential mechanism linking obesity and cancer, results from an imbalance between activation/inactivation of reactive oxygen species, byproducts of cellular metabolism. In a randomized controlled trial, we investigated effects of diet and/or exercise on biomarkers of oxidative stress. A total of 439 overweight/obese [body mass index (BMI) > 25 kg/m²] postmenopausal women, ages 50 of 75 years, were randomized to 12 months of (i) reduced-calorie weight loss diet ("diet"; n = 118); (ii) moderate-to-vigorous intensity aerobic exercise ("exercise"; n = 117); (iii) combined diet and exercise intervention ("diet + exercise"; n = 117); or (iv) control (n = 87). Outcomes were circulating markers of oxidative stress, including fluorescent oxidation products (FOP), F₂-isoprostanes, and oxidized low-density lipoprotein (LDL). On average, participants were 57.9 years, with a BMI of 30.9 kg/m² F₂-isprostanes were significantly reduced in the diet (-22.7%, P = 0.0002) and diet + exercise (-23.5%, P < 0.0001) arms versus controls (-2.99%) and nonsignificantly reduced in the exercise arm (-14.5%, P = 0.01). Participants randomized to the diet and diet + exercise arms had significant increases in levels of FOP [control -5.81%; diet +14.77% (P = 0.0001); diet + exercise +17.45%, (P = 0.0001)]. In secondary analyses, increasing weight loss was statistically significantly associated with linear trends of greater reductions in oxidized LDL and in F₂-isoprostanes and increases in FOP. Compared with controls, exercise participants whose maximal oxygen consumption increased had significant decreases in levels of F₂-isoprostanes and in oxidized LDL and increases in FOP. Dietary weight loss, with or without exercise, significantly reduced some markers of oxidative stress in postmenopausal women. Cancer Prev Res; 9(11); 835-43. ©2016 AACR.

Oxidative Stress and Breast Cancer Risk in Premenopausal Women

BACKGROUND

Detrimental effects of oxidative stress are widely recognized, but induction of apoptosis and senescence may also have benefits for cancer prevention. Recent studies suggest oxidative stress may be associated with lower breast cancer risk before menopause.

METHODS

We conducted a nested case-control study (N = 457 cases, 910 controls) within the NIEHS Sister Study cohort of 50,884 women. Premenopausal women ages 35-54 were eligible for selection. We matched controls 2:1 to cases on age and enrollment year and were breast cancer-free at the time of the corresponding case's diagnosis. Oxidative stress was measured by urinary F2-isoprostane and metabolite (15-F2t-isoprostane-M) concentrations. Odds ratios (OR) and 95% confidence intervals (CIs) were calculated with multivariable conditional logistic regression.

RESULTS

After multivariable adjustment for body mass index (BMI) and other potential confounders, the OR for breast cancer comparing the >90th (≥2.94 ng/mgCr) to <25th percentile (1.01 ng/mgCr) was 1.1 (CI: 0.65, 1.7) for F2-isoprostane and 0.70 (CI: 0.43, 1.1) for the metabolite. Higher metabolite concentrations were associated with lower breast cancer risk among women who were also premenopausal (353 cases, OR: 0.59, CI: 0.34, 1.0) or <46 years (82 cases, OR: 0.15, CI: 0.06, 0.42) at diagnosis. ORs for the metabolite and breast cancer were inverse among women with BMI 18.5-24.9 kg/m (OR: 0.47, CI: 0.18, 1.2, 208 cases) and >30 kg/m (OR: 0.71, CI: 0.30, 1.7, 107 cases), but not among women with BMI 25-29.9 kg/m (OR: 0.98, CI: 0.39, 2.5, 138 cases).

CONCLUSIONS

Together with other studies, our results support a possible inverse association between oxidative stress and premenopausal breast cancer risk.

Discriminating patients with early-stage breast cancer from benign lesions by detection of oxidative DNA damage biomarker in urine

Breast cancer is one of the most commonly diagnosed and death-related cancers in women worldwide. Mammography is routinely used for screening and invasive examinations such as painful tissue biopsies were recommended for patients with abnormal screening outcomes. However, a considerable proportion of these cases turn out to be benign lesions. Thus, novel non-invasive approach for discriminating breast cancer from benign lesions is desirable. Herein, we applied a high-throughput ultra performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) analysis to determine the oxidative DNA damage biomarker, 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) in urine samples from 60 patients with early-stage breast cancer (stage I, II), 51 patients with benign breast diseases and 73 healthy volunteers. We demonstrated that the concentration of urinary 8-oxodG in patients with early-stage breast cancer was significantly higher not only than that in healthy controls, but also than that in patients with benign breast diseases, whereas no significant difference of urinary 8-oxodG level was observed between benign breast diseases group and healthy control group. Moreover, there was significant difference between early-stage breast cancer group and non-cancerous group which consisted of benign breast diseases patients and healthy controls. Besides, logistic regression analysis and receiver operator characteristic (ROC) curve analysis were also performed. Our findings indicate that the marked increase of 8-oxodG in urine may serve as a potential biomarker for the risk estimation, early screening and detection of breast cancer, particularly for discriminating early-stage breast cancer from benign lesions.

Evaluation of serum levels of 8-oxo-2′-deoxyguanosine as a prognostic factor in nonmetastatic breast cancer patients

Aim: 8-OxodG protein has been introduced recently as a new biomarker for breast cancer, according to its role in tumor progression and invasion. In this study, we investigated prognostic value of 8-Oxo-2′-deoxyguanosine (8-OxodG) protein in nonmetastatic breast cancer patients excluding confounding factor. Materials & methods: Before any adjuvant chemotherapy or surgery, serum level of 8-OxodG protein was determined in 79 patients with nonmetastatic breast cancer. All patients follow up for 5 years regarding cancer recurrence and survival. Results: Cumulative risk of recurrence 5 years after the beginning of the study was 0.86 and there was no significant correlation between 8-OxodG and the recurrence rate (p = 0.78). Conclusion: The serum levels of 8-OxodG protein may not be an appropriate prognostic factor in breast cancer.

The Role of Biomarkers of Oxidative Stress in Breast Cancer Risk and Prognosis: A Systematic Review of the Epidemiologic Literature

BACKGROUND

Oxidative stress may play an important role in both initiation and progression of breast cancer. We conducted the first systematic epidemiologic review to summarize the published literature on oxidative stress biomarkers and breast cancer.

MATERIALS AND METHODS

We implemented systematic search strategies to identify published studies of oxidative stress biomarkers and (1) risk of developing breast cancer and (2) breast cancer prognosis using the PRISMA statement guidelines.

RESULTS

We identified eleven case-control studies of oxidative stress biomarkers and breast cancer. Biomarkers utilized varied and menopausal status was a key modifying factor. Across three nested case-control studies with biomarkers measured before diagnosis, one reported increased risk of postmenopausal breast cancer in association with 8-oxodG (DNA damage biomarker), while two (one of F₂-isoprostanes and one of fluorescent oxidation products) reported inverse associations for premenopausal breast cancer only. We identified eight prognostic studies. Two reported associations for lipid peroxidation and breast cancer prognosis; results for other studies were null.

CONCLUSIONS

DNA damage may increase risk of breast cancer among postmenopausal women, while lipid peroxidation may be inversely associated with premenopausal breast cancer. Lipid peroxidation may be associated with survival after breast cancer diagnosis; however, results require evaluation in large, prospective cohort studies.

Oxidant stress as a major determinant of platelet activation in invasive breast cancer

The hypothesis that increased oxidative stress in breast cancer (BC) patients could induce enhanced lipid peroxidation, which, in turn, would contribute to platelet activation and poor clinical outcome is attractive. To address this issue, we investigated pre-surgical urinary 8-iso-prostaglandin (PG)F_2α (marker of in vivo oxidative stress) and 11-dehydro-thromboxane (TX)B₂ (marker of in vivo platelet activation) levels in patients with primary BC (n = 115) compared with control women paired for comorbidities and their association with patients' metabolic profile and clinical prognostic factors. The results obtained showed that presurgical urinary excretion of both biomarkers was enhanced in BC patients compared to controls and was associated with patients' estrogen receptor (ER) expression, but not HER2 status or Ki67 proliferation index. Accordingly, both urinary biomarkers were increased in patients with luminal-like BC molecular subtypes compared with triple negative or HER2-enriched tumors. ER status was an independent predictor of 8-iso-PGF_2α urinary levels, which, in turn, significantly predicted 11-dehydro-TXB₂ urinary levels together with disease stage and ER status. The prognostic value of 11-dehydro-TXB₂ was then evaluated showing a significant correlation with BC pathological response to neoadjuvant treatment. Furthermore, among relapsing patients, those with elevated urinary biomarker levels were more likely to develop distant metastasis rather than local recurrence. In conclusion, we may speculate that enhanced oxidative stress due to estrogen-related mechanisms might cause a condition of persistent platelet activation capable of sustaining BC growth and progression through the release of bioactive stored molecules, ultimately contributing to tumor invasiveness. Further studies specifically addressing this hypothesis are presently needed.

Effects of exercise on markers of oxidative stress: an Ancillary analysis of the Alberta Physical Activity and Breast Cancer Prevention Trial

BACKGROUND

Oxidative stress may contribute to cancer aetiology through several mechanisms involving damage to DNA, proteins and lipids leading to genetic mutations and genomic instability. The objective of this study was to determine the effects of aerobic exercise on markers of oxidative damage and antioxidant enzymes in postmenopausal women.

METHODS

The Alberta Physical Activity and Breast Cancer Prevention Trial (ALPHA) was a two-centre, two-armed randomised trial of 320 inactive, healthy, postmenopausal women aged 50-74 years. Participants were randomly assigned to a year-long exercise intervention (225 min/week) or a control group while being asked to maintain a normal diet. Fasting blood samples were obtained and plasma concentrations of two oxidative damage markers (8-hydroxy-2'-deoxyguanosine (8-OHdG) and 8-isoprostaglandin F2α (8-Iso-PGF2α)) and two antioxidant enzymes (superoxide dismutase and catalase) were measured at baseline, 6 months and 12 months. Intention-to-treat (ITT) and per-protocol analyses were performed using linear mixed models adjusted for baseline biomarker concentrations. A further exercise adherence analysis, based on mean minutes of exercise per week, was also performed.

RESULTS

In the ITT and per-protocol analyses, the exercise intervention did not have any statistically significant effect on either oxidative damage biomarkers or antioxidant enzyme activity.

CONCLUSIONS

A year-long aerobic exercise intervention did not have a significant impact on oxidative stress in healthy, postmenopausal women.

TRIAL REGISTRATION NUMBER

NCT00522262.

Oxidative stress in relation to diet and physical activity among premenopausal women

Higher levels of oxidative stress, as measured by F2-isoprostanes, have been associated with chronic diseases such as CVD and some cancers. Improvements in diet and physical activity may help reduce oxidative stress; however, previous studies regarding associations between lifestyle factors and F2-isoprostane concentrations have been inconsistent. The aim of this cross-sectional study was to investigate whether physical activity and intakes of fruits/vegetables, antioxidant nutrients, dietary fat subgroups and alcohol are associated with concentrations of F2-isoprostane and the major F2-isoprostane metabolite. Urinary F2-isoprostane and its metabolite were measured in urine samples collected at enrolment from 912 premenopausal women (aged 35-54 years) participating in the Sister Study. Physical activity, alcohol consumption and dietary intakes were self-reported via questionnaires. With adjustment for potential confounders, the geometric means of F2-isoprostane and its metabolite were calculated according to quartiles of dietary intakes, alcohol consumption and physical activity, and linear regression models were used to evaluate trends. Significant inverse associations were found between F2-isoprostane and/or its metabolite and physical activity, vegetables, fruits, vitamin C, α-carotene, vitamin E, β-carotene, vitamin A, Se, lutein+zeaxanthin and long-chain n-3 fatty acids. Although trans fats were positively associated with both F2-isoprostane and its metabolite, other dietary fat subgroups including SFA, n-6 fatty acids, n-3 fatty acids, MUFA, PUFA, short-chain n-3 fatty acids, long-chain n-3 fatty acids and total fat were not associated with either F2-isoprostane or its metabolite. Our findings suggest that lower intake of antioxidant nutrients and higher intake of trans fats may be associated with greater oxidative stress among premenopausal women.

Assessment of Isoprostanes in Human Plasma: Technical Considerations and the Use of Mass Spectrometry

Oxygenated lipid mediators released from non-enzymatic peroxidation of polyunsaturated fatty acids (PUFA) are known to have functional roles in humans. Notably, among these lipid mediators, isoprostanes molecules are robust biomarkers of oxidative stress but those from n-3 PUFA are also bioactive molecules. In order to identify and assess the isoprostanes, the use of mass spectrometry (MS) for analysis is preferable and has been used for over two decades. Gas chromatography (GC) is commonly coupled to the MS to separate the derivatized isoprostanes of interest in biological samples. In order to increase the accuracy of the analytical performance, GC-MS/MS was also applied. Lately, MS or MS/MS has been coupled with high-performance liquid chromatography to assess multiple isoprostane molecules in a single biological sample without derivatization process. However, there are limitations for the use of LC-MS/MS in the measurement of plasma isoprostanes, which will be discussed in this review.

Plasma fluorescent oxidation products and risk of estrogen receptor-negative breast cancer in the Nurses' Health Study and Nurses' Health Study II

Findings from epidemiologic studies of oxidative stress biomarkers and breast cancer have been mixed, although no studies have focused on estrogen receptor-negative (ER-) tumors which may be more strongly associated with oxidative stress. We examined prediagnostic plasma fluorescent oxidation products (FlOP), a global biomarker of oxidative stress, and risk of ER- breast cancer in a nested case-control study in the Nurses' Health Study and Nurses' Health Study II. ER- breast cancer cases (n = 355) were matched to 355 controls on age, month/time of day of blood collection, fasting status, menopausal status, and menopausal hormone use. Conditional logistic regression models were used to examine associations of plasma FlOP at three emission wavelengths (FlOP_360, FlOP_320, and FlOP_400) and risk of ER- breast cancer. We did not observe any significant associations between FlOP measures and risk of ER- breast cancer overall; the RRQ4vsQ1 (95 %CI) 0.70 (0.43-1.13), p trend = 0.09 for FlOP_360; 0.91(0.56-1.46), p trend = 0.93 for FlOP_320; and 0.62 (0.37-1.03), p trend = 0.10 for FlOP_400. Results were similar in models additionally adjusted for total carotenoid levels and in models stratified by age and total carotenoids. Although high (vs. low) levels of FIOP_360 and FIOP_400 were associated with lower risk of ER- breast cancer in lean women (body mass index (BMI) < 25 kg/m(2)) but not in overweight/obese women, these differences were not statistically significant (pint = 0.23 for FlOP_360; pint = 0.37 for FlOP_400). Our findings suggest that positive associations of plasma FlOP concentrations and ER- breast cancer risk are unlikely.

Altered Levels of Salivary 8-oxo-7-hydrodeoxyguanosine in Breast Cancer

Oxidative stress has been implicated in the pathogenesis of breast cancer (BC). To determine whether BC is associated with altered salivary redox homeostasis, we performed a case-control study assessing the relationship between BC and 8-oxo-7-hydrodeoxyguanosine (8-oxodG), a marker for oxidative damage to DNA. Enzyme-linked immunosorbent assay for 8-oxodG was used on whole, unstimulated saliva of 134 BC patients and 226 healthy controls. Associations of the redox data were assessed by analysis of variance and logistic regression analysis. Our results revealed that there were 1) significantly lower mean levels of salivary 8-oxodG in BC patients versus controls ( P = 0.0005), 2) significantly lower levels among participants who did not receive radiotherapy and/or chemotherapy as compared with controls ( P < 0.0001), 3) significantly lower levels among BC patients who did not receive these treatments than among those who did ( P < 0.02), 4) and no significant differences in mean 8-oxodG levels among BC patients positive or negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 ( P ≥ 0.08). Our results suggest that BC is associated with decreased levels of oxidatively modified DNA in saliva. Knowledge Transfer Statement: The results of our current case-control study indicate that the molecular biomarker of oxidative stress 8-oxo-7-hydrodeoxyguanosine, measured from saliva, is associated with breast cancer. Our findings may provide the basis for future studies on molecular biomarkers of oxidative stress and breast cancer using saliva as an accessible and noninvasive tissue.

Esophageal squamous cell cancer in a highly endemic region

AIM: To identify risk factors associated with esophageal cancer in Zambia and association between dietary intake and urinary 8-iso prostaglandin F2α (8-isoPGF2α).

METHODS: We conducted a prospective, case control study at the University Teaching Hospital. Subjects included both individuals admitted to the hospital and those presenting for an outpatient upper endoscopy. Esophageal cancer cases were compared to age and sex-matched controls. Cases were defined as patients with biopsy proven esophageal cancer; controls were defined as subjects without endoscopic evidence of esophageal cancer. Clinical and dietary data were collected using a standard questionnaire, developed a priori. Blood was collected for human immunodeficiency virus (HIV) serology. Urine was collected, and 8-isoPGF2α was measured primarily by enzyme-linked immunosorbent assay and expressed as a ratio to creatinine.

RESULTS: Forty five controls (mean age 54.2 ± 15.3, 31 male) and 27 cases (mean age 54.6 ± 16.4, 17 males) were studied. Body mass index was lower in cases (median 16.8) than controls (median 23.2), P = 0.01. Histopathologically, 25/27 (93%) were squamous cell carcinoma and 2/27 (7%) adenocarcinoma. More cases smoked cigarettes (OR = 11.24, 95%CI: 1.37-92.4, P = 0.02) but alcohol consumption and HIV seropositivity did not differ significantly (P = 0.14 for both). Fruit, vegetables and fish consumption did not differ significantly between groups (P = 0.11, 0.12, and 0.10, respectively). Mean isoprostane level was significantly higher in cases (0.03 ng/mg creatinine) than controls (0.01 ng/mg creatinine) (OR = 2.35, 95%CI: 1.19-4.65, P = 0.014).

CONCLUSION: Smoking and isoprostane levels were significantly associated with esophageal cancer in Zambians, but diet, HIV status, and alcohol consumption were not.

Identification of lung cancer histology-specific variants applying Bayesian framework variant prioritization approaches within the TRICL and ILCCO consortia

Large-scale genome-wide association studies (GWAS) have likely uncovered all common variants at the GWAS significance level. Additional variants within the suggestive range (0.0001> P > 5×10(-8)) are, however, still of interest for identifying causal associations. This analysis aimed to apply novel variant prioritization approaches to identify additional lung cancer variants that may not reach the GWAS level. Effects were combined across studies with a total of 33456 controls and 6756 adenocarcinoma (AC; 13 studies), 5061 squamous cell carcinoma (SCC; 12 studies) and 2216 small cell lung cancer cases (9 studies). Based on prior information such as variant physical properties and functional significance, we applied stratified false discovery rates, hierarchical modeling and Bayesian false discovery probabilities for variant prioritization. We conducted a fine mapping analysis as validation of our methods by examining top-ranking novel variants in six independent populations with a total of 3128 cases and 2966 controls. Three novel loci in the suggestive range were identified based on our Bayesian framework analyses: KCNIP4 at 4p15.2 (rs6448050, P = 4.6×10(-7)) and MTMR2 at 11q21 (rs10501831, P = 3.1×10(-6)) with SCC, as well as GAREM at 18q12.1 (rs11662168, P = 3.4×10(-7)) with AC. Use of our prioritization methods validated two of the top three loci associated with SCC (P = 1.05×10(-4) for KCNIP4, represented by rs9799795) and AC (P = 2.16×10(-4) for GAREM, represented by rs3786309) in the independent fine mapping populations. This study highlights the utility of using prior functional data for sequence variants in prioritization analyses to search for robust signals in the suggestive range.

High 15-F2t-Isoprostane Levels in Patients with a Previous History of Nonmelanoma Skin Cancer: The Effects of Supplementary Antioxidant Therapy

BACKGROUND

Phase I of this study was aimed at comparing the profiles of oxidative stress biomarkers in patients with history of nonmelanoma skin cancer (NMSC), previously treated with surgery, to the healthy subjects. Phase II aimed to evaluate the effects of supplementary antioxidant therapy on the levels of biomarkers in the case group.

MATERIALS AND METHODS

In Phase I, oxidative stress biomarkers were measured in blood samples obtained from 24 healthy subjects and 60 patients with history of NMSC previously treated with surgery. In Phase II, the 60 patients with history of NMSC were randomized into two subgroups, one receiving placebo (n = 34) and the other (n = 26) receiving vitamin C, vitamin E, and zinc supplementation for 8 weeks, followed by reevaluation of biomarkers.

RESULTS

In Phase I, patients with history of NMSC showed increased plasma concentrations of all biomarkers, but only 15-F2t-isoprostane was significantly higher than in the healthy subjects. Risk of NMSC increased by 4% for each additional 1 pg/mL increase in 15-F2t-isoprostane. In Phase II, supplementation did not significantly reduce levels of oxidative stress biomarkers.

CONCLUSION

Patients with history of NMSC had significantly high 15-F2t-isoprostane plasma levels; supplementation did not result in significant reduction of oxidative stress biomarkers. This trial was registered with ClinicalTrials.gov (ID NCT02248584).

A Central Role for JNK/AP-1 Pathway in the Pro-Oxidant Effect of Pyrrolidine Dithiocarbamate through Superoxide Dismutase 1 Gene Repression and Reactive Oxygen Species Generation in Hematopoietic Human Cancer Cell Line U937

Pyrrolidine dithiocarbamate (PDTC) known as antioxidant and specific inhibitor of NF-κB was also described as pro-oxidant by inducing cell death and reactive oxygen species (ROS) accumulation in cancer. However, the mechanism by which PDTC indices its pro-oxidant effect is unknown. Therefore, we aimed to evaluate the effect of PDTC on the human Cu/Zn superoxide dismutase 1 (SOD1) gene transcription in hematopoietic human cancer cell line U937. We herein show for the first time that PDTC decreases SOD1 transcripts, protein and promoter activity. Furthermore, SOD1 repression by PDTC was associated with an increase in oxidative stress as evidenced by ROS production. Electrophoretic mobility-shift assays (EMSA) show that PDTC increased binding of activating protein-1 (AP-1) in dose dependent-manner suggesting that the MAPkinase up-stream of AP-1 is involved. Ectopic NF-κB p65 subunit overexpression had no effect on SOD1 transcription. In contrast, in the presence of JNK inhibitor (SP600125), p65 induced a marked increase of SOD1 promoter, suggesting that JNK pathway is up-stream of NF-κB signaling and controls negatively its activity. Indeed, using JNK deficient cells, PDTC effect was not observed nether on SOD1 transcription or enzymatic activity, nor on ROS production. Finally, PDTC represses SOD1 in U937 cells through JNK/c-Jun phosphorylation. Taken together, these results suggest that PDTC acts as pro-oxidant compound in JNK/AP-1 dependent-manner by repressing the superoxide dismutase 1 gene leading to intracellular ROS accumulation.

Genetic polymorphisms in DNA repair and oxidative stress pathways may modify the association between body size and postmenopausal breast cancer

PURPOSE

Obesity is associated with increased bioavailability of estrogen, hyperinsulinemia, and chronic inflammation, all of which may promote tumor growth. Given DNA repair and oxidative stress pathways may work together with these mechanisms to influence carcinogenesis, we hypothesized that genetic variation in these pathways may modify the obesity-postmenopausal breast cancer (BC) association.

METHODS

Resources from a population-based case-control study (990 cases and 970 controls) were used to construct logistic regression models. Body mass index (BMI, weight [kilogram]/height [square meter]) was assessed 1 year before reference date. We characterized interactions between BMI and 29 genetic polymorphisms in oxidative stress and DNA repair pathways.

RESULTS

Age-adjusted odds ratios (95% confidence intervals) for postmenopausal BC were 1.24 (1.00-1.52) and 1.35 (1.09-1.71) for 25 ≥ BMI < 30 and BMI ≥ 30 kg/m(2), respectively. We observed multiplicative interactions (P ≤ .05) for eight gene polymorphisms in DNA repair and oxidative stress pathways. For example, among MPO variant allele carriers, obesity was associated with a twofold increased risk of postmenopausal BC (2.13 [1.35-3.36]); however, in wild-type homozygotes, the relationship was less pronounced (1.33 [0.93-1.89]). Our findings were no longer significant after Bonferroni correction.

CONCLUSIONS

Obesity may be particularly deleterious for postmenopausal BC development in the presence of biologically plausible DNA repair or oxidative stress genotypes.

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."

Consumption of a high glycemic load but not a high glycemic index diet is marginally associated with oxidative stress in young women

Research studies have suggested that chronic consumption of high glycemic index foods may lead to chronically high oxidative stress. This is important because oxidative stress is suspected to be an early event in the etiology of many disease processes. We hypothesized that dietary glycemic index and glycemic load were positively associated with oxidative stress assessed by plasma F2-isoprostanes in healthy, premenopausal women (body mass index [BMI] = 24.7 ± 4.8 kg/m(2) and age 25.3 ± 3.5 years, mean ± SD). We measured plasma F2-isoprostanes in 306 healthy premenopausal women at the baseline visit for the Women In Steady Exercise Research study, using gas chromatography-mass spectrometry. Dietary glycemic index and load were calculated from the National Cancer Institute Diet History Questionnaire, and participants were divided into quartiles of dietary glycemic index and of glycemic load. Plasma F2-isoprostanes were compared across quartile groups of dietary glycemic index and glycemic load using linear regression models. Plasma F2-isoprostanes (pg/mL) increased with quartile of glycemic load (test for linear trend, P = .033), and also increased with quartile of glycemic index in participants with BMI ≥ 25 (P = .035) but not in those with BMI <25 (P = .924). After adjustment for BMI, alcohol consumption and total energy intake, both these positive trends remained marginally significant (P = .123 for quartiles of glycemic index and P = .065 for quartiles of glycemic load).

Inflammation and oxidative stress markers and esophageal adenocarcinoma incidence in a Barrett's esophagus cohort

BACKGROUND

Persons with Barrett's esophagus experience increased risk of esophageal adenocarcinoma. Prediagnostic inflammation markers predict several cancers, but their role in predicting esophageal adenocarcinoma is unknown.

METHODS

We investigated whether biomarkers of inflammation [C-reactive protein (CRP), interleukin-6 (IL6), soluble tumor necrosis factor (sTNF) receptors I and II], and of oxidative stress (F2-isoprostanes) predicted progression to esophageal adenocarcinoma in a prospective cohort of 397 patients with Barrett's esophagus, 45 of whom developed esophageal adenocarcinoma. Biomarkers were measured in stored plasma samples from two time points during follow-up, the mean of which served as the primary predictor. Adjusted hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox regression.

RESULTS

CRP level above the median was associated with an 80% increased risk of esophageal adenocarcinoma. The HR and 95% CI adjusted for age, gender, and further adjusted for waist-hip ratio and smoking were 1.98 (1.05-3.73) and 1.77 (0.93-3.37), respectively, with Ptrend for continuous CRP = 0.04. Persons with IL6 levels above the median also had almost 2-fold increased risk [HR and 95% CI adjusted for age and gender, and further adjusted for waist-hip ratio and smoking were 1.95 (1.03-3.72) and 1.79 (0.93-3.43), respectively, but no evidence of a trend was observed]. Concentrations of TNF receptors and F2-isoprostanes were not associated with esophageal adenocarcinoma risk.

CONCLUSIONS

Further research is needed to evaluate the role of inflammation and associated markers in esophageal adenocarcinoma development in persons with Barrett's esophagus.

IMPACT

This prospective study suggests that inflammation markers, particularly CRP and IL6, may help identify persons at higher risk of progression to esophageal adenocarcinoma.

A review of the application of inflammatory biomarkers in epidemiologic cancer research

Inflammation is a facilitating process for multiple cancer types. It is believed to affect cancer development and progression through several etiologic pathways, including increased levels of DNA adduct formation, increased angiogenesis, and altered antiapoptotic signaling. This review highlights the application of inflammatory biomarkers in epidemiologic studies and discusses the various cellular mediators of inflammation characterizing the innate immune system response to infection and chronic insult from environmental factors. Included is a review of six classes of inflammation-related biomarkers: cytokines/chemokines, immune-related effectors, acute-phase proteins, reactive oxygen and nitrogen species, prostaglandins and cyclooxygenase-related factors, and mediators such as transcription factors and growth factors. For each of these biomarkers, we provide a brief overview of the etiologic role in the inflammation response and how they have been related to cancer etiology and progression within the literature. We provide a discussion of the common techniques available for quantification of each marker, including strengths, weaknesses, and potential pitfalls. Subsequently, we highlight a few under-studied measures to characterize the inflammatory response and their potential utility in epidemiologic studies of cancer. Finally, we suggest integrative methods for future studies to apply multifaceted approaches to examine the relationship between inflammatory markers and their roles in cancer development.

Effects of a green tea extract, Polyphenon E, on systemic biomarkers of growth factor signalling in women with hormone receptor-negative breast cancer

BACKGROUND

Observational and experimental data support a potential breast cancer chemopreventive effect of green tea.

METHODS

We conducted an ancillary study using archived blood/urine from a phase IB randomised, placebo-controlled dose escalation trial of an oral green tea extract, Polyphenon E (Poly E), in breast cancer patients. Using an adaptive trial design, women with stage I-III breast cancer who completed adjuvant treatment were randomised to Poly E 400 mg (n = 16), 600 mg (n = 11) and 800 mg (n = 3) twice daily or matching placebo (n = 10) for 6 months. Blood and urine collection occurred at baseline, and at 2, 4 and 6 months. Biological endpoints included growth factor [serum hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF)], lipid (serum cholesterol, triglycerides), oxidative damage and inflammatory biomarkers.

RESULTS

From July 2007-August 2009, 40 women were enrolled and 34 (26 Poly E, eight placebo) were evaluable for biomarker endpoints. At 2 months, the Poly E group (all dose levels combined) compared to placebo had a significant decrease in mean serum HGF levels (-12.7% versus +6.3%, P = 0.04). This trend persisted at 4 and 6 months but was no longer statistically significant. For the Poly E group, serum VEGF decreased by 11.5% at 2 months (P = 0.02) and 13.9% at 4 months (P = 0.05) but did not differ compared to placebo. At 2 months, there was a trend toward a decrease in serum cholesterol with Poly E (P = 0.08). No significant differences were observed for other biomarkers.

CONCLUSIONS

Our findings suggest potential mechanistic actions of tea polyphenols in growth factor signalling, angiogenesis and lipid metabolism.

Nutritional countermeasures targeting reactive oxygen species in cancer: from mechanisms to biomarkers and clinical evidence

Reactive oxygen species (ROS) exert various biological effects and contribute to signaling events during physiological and pathological processes. Enhanced levels of ROS are highly associated with different tumors, a Western lifestyle, and a nutritional regime. The supplementation of food with traditional antioxidants was shown to be protective against cancer in a number of studies both in vitro and in vivo. However, recent large-scale human trials in well-nourished populations did not confirm the beneficial role of antioxidants in cancer, whereas there is a well-established connection between longevity of several human populations and increased amount of antioxidants in their diets. Although our knowledge about ROS generators, ROS scavengers, and ROS signaling has improved, the knowledge about the direct link between nutrition, ROS levels, and cancer is limited. These limitations are partly due to lack of standardized reliable ROS measurement methods, easily usable biomarkers, knowledge of ROS action in cellular compartments, and individual genetic predispositions. The current review summarizes ROS formation due to nutrition with respect to macronutrients and antioxidant micronutrients in the context of cancer and discusses signaling mechanisms, used biomarkers, and its limitations along with large-scale human trials.

Plasma florescent oxidation products and breast cancer risk: repeated measures in the Nurses' Health Study

Reactive oxygen species (ROS), normally generated through biologic processes, may damage DNA, lipids, and proteins. ROS are balanced through enzymatic mechanisms and exogenous antioxidants; imbalance results in oxidative stress. Limited data suggest an association between oxidative stress and breast cancer. We evaluated pre-diagnostic plasma fluorescent oxidation products (FlOP), a global biomarker of oxidative stress, and breast cancer risk in a nested case-control study in the Nurses' Health Study. Participants provided two blood samples (1989-1990 and 2000-2002) (N = 18,743). 377 women developed breast cancer between the second collection and June 1, 2006. Cases were matched to 377 controls. Relative fluorescent intensity at three different excitation/emission wavelengths (FlOP_360, FlOP_320, FlOP_400) were quantified in both samples, providing distant (≥10 years before diagnosis) and proximate (≤6 years before diagnosis) measures of oxidative stress. We observed no association between FlOP and breast cancer risk in proximate or distant samples (e.g., proximate extreme quartiles: FlOP_360, RR 0.8, 95 % CI 0.5-1.3, p trend = 0.49; FlOP_320, RR 1.1, 95 % CI 0.7-1.7, p trend = 0.53; FlOP_400, RR 1.3, 95 % CI 0.8-2.0, p trend = 0.80). In general no association was observed when cross-classifying or averaging proximate and distant exposure (e.g., extreme quartile of averages: FlOP_360, OR 0.9, 95 % CI 0.6-1.4, p trend = 0.82; FlOP_400, OR 0.9, 95 % CI 0.6-1.4, p trend = 0.55), with the exception of a significant trend for average FlOP_320 (extreme quartiles, OR 1.6, 95 % CI 1.0-2.4, p trend = 0.02). We did not observe important associations between FlOP and breast cancer risk in this large prospective study, though our data suggest women with consistently high FlOP_320 may be at increased risk.

Levothyroxine and lung cancer in females: the importance of oxidative stress

BACKGROUND

Levothyroxine (LT4) treatment can lead to iatrogenic hyperthyroidism and oxidative stress that can cause patient discomfort. Oxidative stress is also recognized as one of the causes of chronic diseases and cancer.

METHODS

The prevalence of breast, colorectal, gastric and lung cancer in 18 Italian Regions during 2010 was correlated with the sales of LT4 in 2009. The cancer prevalence was analyzed in women aged 30-84. This age range corresponds to more than 80% of the consumers of the drug and to about 99% of all malignant cancers. The correlation between sales of LT4 and cancers was determined with the technique of Density Ellipses. The age and smoking contribution for lung cancer was determined with the Sequential test.

RESULTS

No significant correlation was seen between LT4 sales and breast, colorectal and gastric cancers. A significant correlation was instead found for lung cancer (p<0.05) corrected for smoking and age.

CONCLUSIONS

LT4 consumption in Italy is about 0.7 boxes/women/year. There is a correlation between lung cancer and LT4 treatment and oxidative stress caused by LT4 supplementation can be one of the causes. Although we cannot exclude that dysthyroidism needing LT4 supplementation might be the ground for lung cancer itself and measuring oxidative stress could be helpful in avoiding excessive use of the drug.

The antioxidant paradox: less paradoxical now?

The term 'antioxidant paradox' is often used to refer to the observation that oxygen radicals and other reactive oxygen species are involved in several human diseases, but giving large doses of dietary antioxidant supplements to human subjects has, in most studies, demonstrated little or no preventative or therapeutic effect. Why should this be? First, the role of reactive oxygen species in the origin and/or progression of most human diseases is unclear, although they are probably important in cancer, neurodegenerative diseases and perhaps some others. Second, the endogenous antioxidant defences in the human body are complex, interlocking and carefully regulated. The body's 'total antioxidant capacity' seems unresponsive to high doses of dietary antioxidants, so that the amount of oxidative damage to key biomolecules is rarely changed. Indeed, manipulation of endogenous antioxidant levels (e.g. by supplying weak pro-oxidants) may be a more useful approach to treatment and prevention of diseases in which reactive oxygen species are important than is consumption of large doses of dietary antioxidants.

Mitochondrial DNA copy number is associated with breast cancer risk

Mitochondrial DNA (mtDNA) copy number in peripheral blood is associated with increased risk of several cancers. However, data from prospective studies on mtDNA copy number and breast cancer risk are lacking. We evaluated the association between mtDNA copy number in peripheral blood and breast cancer risk in a nested case-control study of 183 breast cancer cases with pre-diagnostic blood samples and 529 individually matched controls among participants of the Singapore Chinese Health Study. The mtDNA copy number was measured using real time PCR. Conditional logistic regression analyses showed that there was an overall positive association between mtDNA copy number and breast cancer risk (P_trend = 0.01). The elevated risk for higher mtDNA copy numbers was primarily seen for women with <3 years between blood draw and cancer diagnosis; ORs (95% CIs) for 2^nd, 3^rd, 4^th, and 5^th quintile of mtDNA copy number were 1.52 (0.61, 3.82), 2.52 (1.03, 6.12), 3.12 (1.31, 7.43), and 3.06 (1.25, 7.47), respectively, compared with the 1^st quintile (P_trend = 0.004). There was no association between mtDNA copy number and breast cancer risk among women who donated a blood sample ≥3 years before breast cancer diagnosis (P_trend = 0.41). This study supports a prospective association between increased mtDNA copy number and breast cancer risk that is dependent on the time interval between blood collection and breast cancer diagnosis. Future studies are warranted to confirm these findings and to elucidate the biological role of mtDNA copy number in breast cancer risk.

Association between 8-oxo-7,8-dihydro-2'-deoxyguanosine excretion and risk of postmenopausal breast cancer: nested case-control study

BACKGROUND

Oxidative stress may be important in carcinogenesis and a possible risk factor for breast cancer. The urinary excretion of oxidatively generated biomolecules, such as 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), represents biomarkers of oxidative stress, reflecting the rate of global damage to DNA in steady state.

METHODS

In a nested case-control design, we examined associations between urinary excretion of 8-oxodG and risk of breast cancer in a population-based cohort of 24,697 postmenopausal women aged 50 to 64 years with 3 to 7 years follow-up. The accruing cases of breast cancer were matched to controls by age at diagnosis, baseline age, and hormone replacement therapy (HRT). Spot urine samples collected at entry was analyzed for 8-oxodG by high-performance liquid chromatography with electrochemical detection. Incidence rate ratio (IRR; 95% confidence intervals) based on 336 matched pairs with all information was estimated per unit increase in 8-oxodG divided by creatinine for all and estrogen receptor (ER) positive and negative breast cancers.

RESULTS

There was a borderline significant positive association between 8-oxodG and risk of all breast cancer (IRR: 1.08; 1.00-1.17 per unit increase in nmol/mmol creatinine). This association was significant with respect to the risk of ER-positive cancer (IRR: 1.11; 1.01-1.23) and among women not using HRT (IRR: 1.11; 0.97-1.26) or with low dietary iron intake (IRR: 1.10; 1.06-1.37 per unit increase) for all breast cancer.

CONCLUSIONS

We observed positive association between 8-oxodG excretion and risk of especially ER-positive breast cancer.

IMPACT

Our results suggest that oxidative stress with damage to DNA is important for the development of breast cancer.

Eicosanoids and adipokines in breast cancer: from molecular mechanisms to clinical considerations

Chronic inflammation is one of the foremost risk factors for different types of malignancies, including breast cancer. Additional risk factors of this pathology in postmenopausal women are weight gain, obesity, estrogen secretion, and an imbalance in the production of adipokines, such as leptin and adiponectin. Various signaling products of transcription factor, nuclear factor-kappaB, in particular inflammatory eicosanoids, reactive oxygen species (ROS), and cytokines, are thought to be involved in chronic inflammation-induced cancer. Together, these key components have an influence on inflammatory reactions in malignant tissue damage when their levels are deregulated endogenously. Prostaglandins (PGs) are well recognized in inflammation and cancer, and they are solely biosynthesized through cyclooxygenases (COXs) from arachidonic acid. Concurrently, ROS give rise to bioactive isoprostanes from arachidonic acid precursors that are also involved in acute and chronic inflammation, but their specific characteristics in breast cancer are less demonstrated. Higher aromatase activity, a cytochrome P-450 enzyme, is intimately connected to tumor growth in the breast through estrogen synthesis, and is interrelated to COXs that catalyze the formation of both inflammatory and anti-inflammatory PGs such as PGE(2), PGF(2α), PGD(2), and PGJ(2) synchronously under the influence of specific mediators and downstream enzymes. Some of the latter compounds upsurge the intracellular cyclic adenosine monophosphate concentration and appear to be associated with estrogen synthesis. This review discusses the role of COX- and ROS-catalyzed eicosanoids and adipokines in breast cancer, and therefore ranges from their molecular mechanisms to clinical aspects to understand the impact of inflammation.