Epigenetic modulation of the retinoid X receptor alpha by green tea in the azoxymethane-Apc Min/+ mouse model of intestinal cancer.

We investigated the possible mechanisms of inhibition of colorectal carcinogenesis by green tea (GT) in azoxymethane-treated (AOM) Apc(Min/+) mice. Mice received water or a 0.6% (w/v) solution of GT as the only source of beverage. GT treatment commenced at the 8th week of age and lasted for 8 wk. The treatment caused a statistically significant reduction in the number of newly formed tumors (28%, P < 0.05). Immunohistochemical analysis showed that GT decreased the levels of beta-catenin and its downstream target cyclin D1. To probe a mechanism, we further investigated the expression of retinoic X receptor alpha (RXR alpha) in AOM/Apc(Min/+) tumors. Our results show that RXR alpha is selectively downregulated in AOM/Apc(Min/+) mouse intestinal tumors. In contrast, other retinoic receptors including retinoic acid receptor alpha (RAR alpha), RAR beta, RXR beta, and RXR gamma were all expressed in Apc(Min/+) adenomas. Furthermore, our results show that RXR alpha downregulation is an early event in colorectal carcinogenesis and is independent of beta-catenin expression. GT significantly increased the protein levels of RXR alpha. In addition, RT-PCR analysis showed that GT induced a similar increase in the levels of RXR alpha mRNA. Genomic bisulfite treatment of colonic DNA followed by pyrosequencing of 24 CpG sites in the promoter region of RXR alpha gene showed a significant decrease in CpG methylation with GT treatment. The results suggest that a low concentration of GT is sufficient to desilence RXR alpha and inhibit intestinal tumorigenesis in the Apc(Min/+) mouse.

Green tea selectively targets initial stages of intestinal carcinogenesis in the AOM-ApcMin mouse model.

One of the liabilities of the Apc(Min) mouse as a model for colon cancer is its lack of a robust tumor response in the large bowel. In our protocol, we treated the Apc(Min) mouse with azoxymethane, a colon-selective carcinogen. This protocol induced a 4-fold increase in the number of colon tumors. We utilized this protocol to investigate the possible mechanisms of inhibition of colorectal carcinogenesis by green tea. Mice received water or a 0.6% (w/v) solution of green tea as the only source of beverage. Green tea treatment commenced at the eighth week of age and lasted for either 4 or 8 weeks. Green tea significantly inhibited the formation of new adenomas, but was ineffective against larger tumors. Mechanistically, we investigated the effects of green tea on the expression of biomarkers involved in colon carcinogenesis. Western blotting analysis showed that green tea decreased the total levels of the early carcinogenesis biomarker beta-catenin and its downstream target cyclin D1. In contrast, the expression of COX-2 was not altered. Immunohistochemical analysis showed that green tea inhibited the formation of adenomas overexpressing beta-catenin and cyclin D1, but did not reduce the number of COX-2-expressing adenomas. Our results suggest that green tea specifically targets initial stages of colon carcinogenesis; the time of administration of green tea is pivotal for effective chemoprevention. Beverage levels of green tea do not inhibit the progress of any large adenomas or adenocarcinomas existing prior to the tea administration.

On use of the multistage dose-response model for assessing laboratory animal carcinogenicity.

We explore how well a statistical multistage model describes dose-response patterns in laboratory animal carcinogenicity experiments from a large database of quantal response data. The data are collected from the US EPA's publicly available IRIS data warehouse and examined statistically to determine how often higher-order values in the multistage predictor yield significant improvements in explanatory power over lower-order values. Our results suggest that the addition of a second-order parameter to the model only improves the fit about 20% of the time, while adding even higher-order terms apparently does not contribute to the fit at all, at least with the study designs we captured in the IRIS database. Also included is an examination of statistical tests for assessing significance of higher-order terms in a multistage dose-response model. It is noted that bootstrap testing methodology appears to offer greater stability for performing the hypothesis tests than a more-common, but possibly unstable, "Wald" test.

Common polymorphisms in 5-lipoxygenase and 12-lipoxygenase genes and the risk of incident, sporadic colorectal adenoma.

BACKGROUND: Lipoxygenases (LOX) are major enzymes that metabolize arachidonic acid to hydroxyl-eicosatetraenoic acids and leukotrienes, which have been implicated in inflammation and colorectal cancer risk. Polymorphisms in LOX genes may influence their function and/or expression and, thus, may modify the risk for colorectal adenoma. The authors investigated the associations of 3 polymorphisms (2 in 5-LOX, -1708 guanine-->adenine and 21 cytosine-->thymine; and 1 in 12-LOX, arginine 261 glutamine [Arg261Gln]) in LOX genes with the risk of colorectal adenoma and also explored possible interactions of these polymorphisms with several inflammation-pathway or arachidonic acid metabolism-pathway related factors with the risk of colorectal adenoma. METHODS: By using data from a community-based, case-control study of incident, sporadic colorectal adenoma that included 162 cases and 211 controls, the authors constructed multiple logistic regression models to estimate the odds ratios (OR) and 95% confidence intervals (95% CI) of colorectal adenoma after adjusting for potential confounders. RESULTS: Overall, there were no significant associations of the 2 5-LOX polymorphisms with the risk of colorectal adenoma. However, there was an inverse association between the Arg261Gln polymorphism in 12-LOX and colorectal adenoma (OR, 0.63; 95% CI, 0.40-1.00). A significant interaction also was observed between the 12-LOX polymorphism (Arg261Gln) and the use of nonsteroidal anti-inflammatory drugs (P(interaction) = .02). CONCLUSIONS: The current results suggested that polymorphisms of LOX genes may act independently or with other factors to affect the risk of colorectal adenoma. Further studies will be needed to confirm these findings. Cancer 2007 (c) 2007 American Cancer Society.

Is risk of axillary lymph node metastasis associated with proximity of breast cancer to the skin?

INTRODUCTION: Risk of axillary lymph node metastasis, the most important predictor of disease-free and overall survival in breast cancer patients, is estimated primarily from histologic features of the primary cancer including tumor size, histologic type and grade, and hormone receptor expression. Based upon a clinical impression, and research showing that palpable cancers are more likely to be node positive, we hypothesized that primary breast cancers more proximal to the skin of the breast are more likely to be positive for axillary lymph node metastasis. METHODS: This is a retrospective medical record review of 209 women with stage T1 or T2 (

Permeation and reservoir formation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P) across porcine esophageal tissue in the presence of ethanol and menthol.

Environmental influences may affect carcinogen absorption and residency in the tissues of the aero-digestive tract. We quantified the effect of ethanol and menthol on the rates of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P) absorption using a fully validated in vitro diffusion system, capable of accurately and precisely quantifying tobacco carcinogen permeation and reservoir formation in porcine esophageal mucosa. Confocal microscopy was employed to visualize the location of B[a]P in the exposed membranes. Markedly different extents of permeation and reservoir formation for the tobacco carcinogens were recorded in the presence of ethanol and menthol. The water-soluble NNK permeated the membrane rapidly, while the lipophilic B[a]P did not appreciably diffuse through the tissue. Significantly different extents of reservoir formation were observed for the different carcinogens and in the presence of the different penetration-enhancer solvents. Alcohol (at 5% concentration) did not influence the permeation or reservoir formation of NNK. A mentholated donor solution (0.08%) both decreased the flux of NNK and significantly increased the tissue reservoir formation. The magnitude of the reservoir formed by B[a]P was relatively extensive (even though membrane permeation rates were negligible), being greatest in the presence of both ethanol and menthol. This suggests synergy between the two penetration-enhancer species acting on this carcinogen. Confocal microscopy studies confirmed that there was an appreciable intra-cellular, and specifically nuclear, association of the B[a]P species during the reservoir formation process. The aqueous solubility of the diffusing species and the presence of penetration enhancers appeared to be key factors in the absorption and cellular binding processes. The results presented support the hypothesis that the use of mentholated cigarettes, or the concomitant consumption of alcohol while smoking, may have marked effects on the fate of tobacco chemicals. This finding may help to explain elevated rates of esophageal squamous cell carcinoma in African Americans.

Urinary estrogen metabolites, prostate specific antigen, and body mass index among African-American men in South Carolina.

INTRODUCTION: Estrogen metabolites have been linked to risk of breast cancer, and we were interested in whether they are associated with prostate specific antigen (PSA) and other factors associated with prostate cancer. African-American (AA) men in South Carolina have among the highest prostate cancer rates in the world, and thus provide an ideal population in which to investigate this hypothesis. METHODS: We recruited AA men attending prostate cancer screenings in and around Columbia, South Carolina. Because very few men had elevated PSAs, we restricted our study to the 77 men whose PSA was below the cutpoint used by the screening program to indicate need for diagnostic workup. These men provided spot urine samples and answered demographic and lifestyle questions including self-reported body weight, height, exercise, tobacco use, medications, cancer history and age. Levels of urinary 2-hydroxyestrone (2-OHE1) and 16alpha-hydroxyestrone (16alpha-OHE1), and their ratio (2/16) and blood PSA levels were determined. RESULTS: After adjusting for a statistically significant interaction between age and BMI, we found a reduction of 14.2% in 2-OHE1 for each 1.0 ng/ml increase in PSA (p=0.05). For obese AA men only (BMI> or =30 kg/m2), 2-OHE1 increased by 36% for each decade of age (p=0.009). CONCLUSIONS: Estrogen metabolites may be related to PSA level in AA men. Older men with BMIs greater than 30 kg/m2 had an unexpected increase in 2-OHE1, suggesting a dysregulation of this estrogen metabolism pathway. Further studies of estrogen metabolites may provide insights into prostate cancer risk factors.

Can hyperbaric oxygen therapy reduce breast cancer treatment-related lymphedema? A pilot study.

OBJECTIVE: Arm lymphedema after surgery or radiation for breast cancer is common, causing pain and limitation of activities. Previous reports of hyperbaric oxygen (HBO) therapy for breast edema led us to consider the use of HBO therapy for arm lymphedema. METHODS: Ten healthy postmenopausal women (age 58 +/- 5.7 years) with persistent (9.4 years +/- 9.1 years) arm lymphedema following breast cancer surgery and radiation (n = 10) plus chemotherapy (n = 7) received 20 HBO treatments (90 minutes at 2.0 ATA five times a week for 4 weeks). End points included changes in upper extremity volume, platelet counts, plasma levels of vascular endothelial growth factor (VEGF), and lymph angiogenic-associated vascular endothelial growth factor-C (VEGF-C). Lymphedema volume (LV) was defined as the volume of the unaffected arm subtracted from the volume of the affected arm. RESULTS: We observed a 38% average reduction in hand lymphedema (-7.4 ml, 11.6 SD, range -30-+8 ml, p = 0.076, 95% confidence interval -15.7-0.9 ml) at the end of HBO, which was independent of changes in body weight. For those who benefited (n = 8), the reduction was persistent from the end of treatment to a final measurement an average of 14.2 months after the last HBO treatment. However, total LV did not change significantly. VEGF-C increased from baseline (p = 0.004) before treatment 20, suggesting HBO had begun to stimulate this growth factor. CONCLUSIONS: Future studies should explore the effects of a greater number of HBO treatments on lymphedema, with more patients.