[Show abstract][Hide abstract] ABSTRACT: Freeze-dried black raspberries (BRB), their component anthocyanins (ACs), and a metabolite of BRB ACs, protocatechuic acid (PCA), inhibit the development of esophagus cancer in rats induced by the carcinogen, N-nitrosomethylbenzylamine (NMBA). All three components reduce inflammation in the esophagus and in plasma. The present study determined the relation of changes in inflammatory markers to infiltration of innate immune cells into NMBA-treated esophagus. Rats were injected with NMBA (0.35 mg/kg) for five weeks while on control diet. Following NMBA treatment, rats were fed diets containing 6.1% BRB powder, an AC-rich fraction of BRBs (3.8 µmoles/g diet), or 500 ppm PCA. At weeks 15, 25 and 35, inflammatory biomarker expression in the plasma and esophagus was quantified and infiltration of immune cells in the esophagus was examined. At all three time points, BRB, AC, and PCA similarly affected cytokine production in the esophagus and plasma of NMBA-treated rats, relative to the NMBA-only control. These included decreased expression of the pro-inflammatory cytokine IL1β, and increased the expression of the anti-inflammatory cytokine IL10. Moreover, all three diets also increased the expression of IL12, a cytokine that activates both cytolytic NK and CD8+ T cells. Additionally, the three diets also decreased infiltration of both macrophages and neutrophils into the esophagus. Overall, our results suggest that another mechanism by which BRBs, ACs, and PCA inhibit NMBA-induced esophageal tumorigenesis is by altering cytokine expression and innate immune cell-trafficking into tumor tissues.
[Show abstract][Hide abstract] ABSTRACT: Differences in internal dose of nicotine and tobacco-derived carcinogens among ethnic/racial groups have been observed. In
this study, we explicitly examined the relationships between genetic ancestries (genome-wide average) and 19 tobacco-derived
biomarkers in smokers from 3 admixed groups in the Multiethnic Cohort Study (1993–present), namely, African ancestry in African
Americans (n = 362), Amerindian ancestry in Latinos (n = 437), and Asian and Native Hawaiian ancestries in Native Hawaiians (n = 300). After multiple comparison adjustment, both African and Asian ancestries were significantly related to a greater level
of free cotinine; African ancestry was also significantly related to lower cotinine glucuronidation (P's < 0.00156). The predicted decrease in cotinine glucuronidation was 8.6% (P = 4.5 × 10−6) per a 20% increase in African ancestry. Follow-up admixture mapping revealed that African ancestry in a 12-Mb region on
chromosome 4q was related to lower cotinine glucuronidation (P's < 2.7 × 10−7, smallest P = 1.5 × 10−9), although this is the same region reported in our previous genome-wide association study. Our results implicate a genetic
ancestral component in the observed ethnic/racial variation in nicotine metabolism. Further studies are needed to identify
the underlying genetic variation that could potentially be ethnic/racial specific.
No preview · Article · Nov 2015 · American Journal of Epidemiology
[Show abstract][Hide abstract] ABSTRACT: Two of the most widely measured compounds in the urine of people who use tobacco products are cotinine, a major metabolite of the addictive constituent nicotine, and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), a metabolite of the powerful lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Thousands of analyses have been reported in the literature, carried out exclusively - to the best of our knowledge - by separate methods. In the study reported here, we have developed a sensitive, accurate, and precise liquid chromatography-electrospray ionization-tandem mass spectrometry-selected reaction monitoring method for the combined analysis of total cotinine (the sum of cotinine and its glucuronide) and total NNAL (the sum of NNAL and its glucuronide). The new method quantifies naturally occurring [13C]cotinine to minimize problems associated with the vast differences in concentration of total cotinine and total NNAL in urine. This method should greatly facilitate future determinations of these important compounds.
No preview · Article · Dec 2014 · Analytical Chemistry
[Show abstract][Hide abstract] ABSTRACT: The metabolic fate of a compound is determined by numerous factors including its chemical structure. Although the metabolic options for a variety of functional groups are well understood, and can often provide a rationale for comparison of toxicity based on structural analogy, at times, quite minor structural variations may have major consequences for metabolic outcomes and toxicity. In this paper, the effects of structural variations on metabolic outcomes is detailed for a group of related hydroxy- and alkoxy- substituted allyl- and propenylbenzenes. These classes of compounds are naturally occurring constituents of a variety of botanical based food items. The classes vary from one another by the presence or absence of alkylation of their para-hydroxyl substituents and/or the position of the double bond in the alkyl side chain. We provide an overview of how these subtle structural variations alter the metabolism of these important food-borne compounds, ultimately influencing their toxicity, particularly their DNA reactivity and carcinogenic potential. The data reveal that detailed knowledge of the consequences of subtle structural variations for metabolism is essential for adequate comparison of structurally related chemicals. Taken together, it is concluded that predictions in toxicological risk assessment should not be performed on the basis of structural analogy only, but should include analogy of metabolic pathways across compounds and species.
No preview · Article · May 2014 · Chemical Research in Toxicology
[Show abstract][Hide abstract] ABSTRACT: The Family Smoking Prevention and Tobacco Control Act gives the Food and Drug Administration power to regulate tobacco products. This commentary calls for immediate regulation of the carcinogenic tobacco-specific nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N'-nitrosonornicotine (NNN) in cigarette tobacco as a logical path to cancer prevention. NNK and NNN, powerful carcinogens in laboratory animals, have been evaluated as "carcinogenic to humans" by the International Agency for Research on Cancer. NNK and NNN are present in the tobacco of virtually all marketed cigarettes; levels in cigarette smoke are directly proportional to the amounts in tobacco. The NNK metabolite NNAL, itself a strong carcinogen, is present in the urine of smokers and non-smokers exposed to secondhand smoke. Some of the highest levels of NNK and NNN are found in U.S. products. It is well established that factors such as choice of tobacco blend, agricultural conditions, and processing methods influence levels of NNK and NNN in cigarette tobacco and cigarette smoke. Therefore, it is time to control these factors and produce cigarettes with 100 ppb or less each of NNK and NNN in tobacco, which would result in an approximate 15-20 fold reduction of these carcinogens in the mainstream smoke of popular cigarettes sold in the United States.
Preview · Article · May 2014 · Cancer Prevention Research
[Show abstract][Hide abstract] ABSTRACT: This publication is the 1st in a series of publications by the Expert Panel of the Flavor and Extract Manufacturers Assoc. summarizing the Panel's 3rd re-evaluation of Generally Recognized as Safe (GRAS) status referred to as the GRASr2 program. In 2011, the Panel initiated a comprehensive program to re-evaluate the safety of more than 2700 flavor ingredients that have previously met the criteria for GRAS status under conditions of intended use as flavor ingredients. Elements that are fundamental to the safety evaluation of flavor ingredients include exposure, structural analogy, metabolism, pharmacokinetics, and toxicology. Flavor ingredients are evaluated individually and in the context of the available scientific information on the group of structurally related substances. Scientific data relevant to the safety evaluation of the use of aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances as flavoring ingredients are evaluated. The group of aliphatic acyclic and alicyclic terpenoid tertiary alcohols and structurally related substances was reaffirmed as GRAS (GRASr2) based, in part, on their rapid absorption, metabolic detoxication, and excretion in humans and other animals; their low level of flavor use; the wide margins of safety between the conservative estimates of intake and the no-observed-adverse effect levels determined from subchronic studies and the lack of significant genotoxic and mutagenic potential.
No preview · Article · Apr 2014 · Journal of Food Science
[Show abstract][Hide abstract] ABSTRACT: Diets containing either freeze-dried black raspberries (BRB) or their polyphenolic anthocyanins (AC) have been shown to inhibit the development of N-nitrosomethylbenzylamine (NMBA)-induced esophageal cancer in rats. The present study was conducted to determine if PCA, a major microbial metabolite of BRB AC, also prevents NMBA-induced esophageal cancer in rats. F344 rats were injected with NMBA three times a week for five weeks and then fed control or experimental diets containing 6.1% BRB, an AC-rich fraction derived from BRB, or PCA. Animals were exsanguinated at weeks 15, 25, & 35 to quantify the development of preneoplastic lesions and tumors in the esophagus, and to relate this to the expression of inflammatory biomarkers. At weeks 15 & 25, all experimental diets were equally effective in reducing NMBA-induced esophageal tumorigenesis, as well as in reducing the expression of Pentraxin-3 (PTX3), a cytokine produced by peripheral blood mononuclear cells in response to IL-1β and TNF-α. All experimental diets were also active at reducing tumorigenesis at week 35; however, the BRB diet was significantly more effective than the AC & PCA diets. Further, all experimental diets inhibited inflammation in the esophagus via reducing biomarker (COX-2, iNOS, p-NF-κB, sEH) and cytokine (PTX3) expression. Overall, our data suggest that BRB, their component AC and PCA inhibit NMBA-induced esophageal tumorigenesis, at least in part, by their inhibitory effects on genes associated with inflammation.
Full-text · Article · Mar 2014 · Cancer Prevention Research
[Show abstract][Hide abstract] ABSTRACT: Cigarette smoking is the major cause of lung cancer in the United States and worldwide. Tobacco products are estimated to cause approximately 90% of lung cancer cases. Experimental studies in laboratory animals have collectively demonstrated the carcinogenicity of cigarette smoke and cigarette smoke condensates (CSCs). There are over 5000 identified chemicals and more than 60 known carcinogens in cigarette smoke, with polycyclic aromatic hydrocarbons (PAHs) and the tobacco-specific nitrosamine NNK (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone) likely being the most important respiratory carcinogens. The carcinogenicity of cigarette smoke can also be enhanced by the presence of tumor promoters and cocarcinogens. The reaction of carcinogens with DNA can cause mutations and, if unrepaired, can lead to the activation of oncogenes or the inactivation of tumor suppressors. Epigenetic changes may also occur from exposure to tobacco carcinogens, leading to a change in gene expression. While the majority of lung cancer results from cigarette smoking, only 15% of smokers get lung cancer. Studies indicate that this may be due to genetic factors that contribute to a person's susceptibility to tobacco-induced cancers. Biomarkers have been developed to monitor uptake and activation of tobacco carcinogens, and perhaps could be used to predict susceptibility to lung cancer. Chemoprevention has developed as an approach to prevent or delay the onset of tobacco-induced lung cancer. However, cessation of tobacco products is the best way to prevent lung cancer.
[Show abstract][Hide abstract] ABSTRACT: Our laboratory has f cancer prevention using freeze-dried berries, mainly black raspberries, for more than two decades. Berries contain many known agents with chemopreventive potential including certain vitamins, minerals, simple and complex polyphenols, phytosterols, and various fiber constituents. Because berries are approximately 80-90 % water, the freeze-drying process concentrates these bioactive constituents approximately tenfold. This chapter describes methods we use to harvest the berries, grind them into a powder, and determine the nutrient, chemical, and microbial content of the powder before use in both preclinical and clinical studies. We have found that berry powder, when added at 5.0-10 % of the diet, protects against chemically induced cancer in the rodent esophagus and colon, and other laboratories have demonstrated protective effects in the rodent oral cavity, mammary gland, and skin. Bio-fractionation studies indicate that the anthocyanins in black raspberries are important for their chemopreventive effects. The berries function to reduce cell proliferation, inflammation, and angiogenesis and to stimulate apoptosis and differentiation, and they influence the expression levels of multiple genes and signaling pathways associated with these cellular functions. Black raspberry and strawberry powders are well tolerated by humans for at least 6-9 months when consumed orally at doses as high as 60 g/day. As an example of their effects in humans, we describe here the ability of black raspberries and strawberries (STRW) to modulate the development of premalignant lesions (Barrett's esophagus and esophageal dysplasia) in the esophagus. We hope that the information and methods in this review will be helpful to others who are considering the use of food-based approaches to cancer prevention.
No preview · Article · Jan 2014 · Methods in Pharmacology and Toxicology
[Show abstract][Hide abstract] ABSTRACT: DNA adduct measurements provide valuable information about DNA damage associated with exposure to specific genotoxicants. N 2-Ethylidene- dGuo, the major DNA adduct formed upon reaction of acetaldehyde with DNA, has been used to investigate mechanisms of alcohol carcinogenesis focusing on the effects of acetaldehyde, the primary metabolite of ethanol. N 2-Ethylidene-dGuo is stable in DNA, but it easily degrades when released as a nucleoside. A liquid-chromatography-electrospray ionization-tandem mass spectrometry-selected reaction monitoring (LC-ESI-MS/MS-SRM) method for the analysis of N2-Ethylidene-dGuoas its reduced form N 2-ethyl-dGuo has been developed. This assay is based on addition of the reducing agent NaBH3CN to the DNA before hydrolysis and on the use of a 15N-labeled analog of N 2-ethyl-dGuo as an internal standard. The addition of the reducing agent and internal standard are followed by enzymatic hydrolysis and sample purification and enrichment. This chapter provides detailed step-by-step information on the analysis of N 2-ethyl-dGuo in DNA by LC-ESI-MS/MS-SRM. The protocol described easily can be applied to DNA isolated from different tissues and cell types and on DNA amounts as low as 5-10 μg.
No preview · Article · Jan 2014 · Methods in Pharmacology and Toxicology
[Show abstract][Hide abstract] ABSTRACT: In 2007, International Agency for Cancer Research presented compelling evidence that linked smokeless tobacco use to the development of human oral cancer. While these findings imply vigorous local carcinogen metabolism, little is known regarding levels and distribution of Phase I, II and drug egress enzymes in human oral mucosa. In the study presented here, we integrated clinical data, imaging and histopathologic analyses of an oral squamous cell carcinoma that arose at the site of smokeless tobacco quid placement in a patient. Immunoblot and immunohistochemical (IHC) analyses were employed to identify tumor and normal human oral mucosal smokeless tobacco-associated metabolic activation and detoxification enzymes. Human oral epithelium contains every known Phase I enzyme associated with nitrosamine oxidative bioactivation with ~2 fold inter-donor differences in protein levels. Previous studies have confirmed ~3.5 fold inter-donor variations in intraepithelial Phase II enzymes. Unlike the superficially located enzymes in non-replicating esophageal surface epithelium, IHC studies confirmed oral mucosal nitrosamine metabolizing enzymes reside in the basilar and suprabasilar region which notably is the site of ongoing keratinocyte DNA replication. Clearly, variations in product composition, nitrosamine metabolism and exposure duration will modulate clinical outcomes. The data presented here form a coherent picture consistent with the abundant experimental data that links tobacco-specific nitrosamines to human oral cancer.
Preview · Article · Nov 2013 · Cancer Prevention Research