We have previously shown that a fish oil-rich diet increased the chemopreventive efficacy of tamoxifen (Tam) against N-methyl-N-nitrosourea (MNU)-induced rat mammary carcinogenesis. Herein, we provide evidence that tamoxifen treatment modifies gene expression of mammary tumors depending upon the type of dietary fat fed to the animals. Rats initiated with MNU and treated with Tam were fed a diet rich in corn oil (CO) or fish oil (FO). After 8 weeks, cribriform tumors were collected and gene expression analysis was performed. Increased RNA expression of genes such as SerpinB10, Wisp2 and Apod in tumors from FO-treated rats is indicative of highly differentiated tumors. Decreased expression of H19 and Igf2 mRNA in Tam-treated groups, and Sncg mRNA in FO+Tam group may be related to tumor growth impairment and lower metastatic capacity. Change in the expression of genes associated with immunity in animals in the FO+Tam group may suggest a shift in the immune response. These data show that, although tamoxifen modulates the expression of genes leading to tumor growth impairment, further modulations of genes are influenced by FO. FO modulation of Tam changes in gene expression accounts for its enhancing chemopreventive effect against MNU-induced mammary carcinogenesis.
fish oil; corn oil; tamoxifen; breast cancer; chemoprevention
Since meat may be involved in the etiology of colorectal cancer, associations between meat-related compounds were examined to elucidate underlying mechanisms in a population-based case-control study. Participants (989 cases/1,033 healthy controls) completed a food frequency questionnaire with a meat-specific module. Multivariable logistic regression was used to examine associations between meat variables and colorectal cancer; polytomous logistic regression was used for subsite-specific analyses. The following significant positive associations were observed for meat-related compounds: 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx) and colorectal, distal colon, and rectal tumors; 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and colorectal and colon cancer tumors; nitrites/nitrates and proximal colon cancer; 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and rectal cancer; and benzo[a]pyrene and rectal cancer (P-trends < 0.05 ). For analyses by meat type, cooking method, and doneness preference, positive associations between red processed meat and proximal colon cancer and pan-fried red meat and colorectal cancer were found (P-trends < 0.05). Inverse associations were observed between unprocessed poultry and colorectal, colon, proximal colon, and rectal tumors; grilled/barbequed poultry and proximal colon cancer; and well-done/charred poultry and colorectal, colon, and proximal colon tumors (P-trends < 0.05). HCAs, PAHs, nitrites, and nitrates may be involved in colorectal cancer etiology. Further examination into the unexpected inverse associations between poultry and colorectal cancer is warranted.
colorectal cancer; meat; heterocyclic amines; polycyclic aromatic hydrocarbons; N-nitroso compounds
We have previously characterized three cell clones that were derived by limiting dilution from a human prostate cancer cell line (LNCaP) representing a phenotypic continuum of cancer progression (1). The present study was undertaken to examine the effects of L-selenomethionine (SeM), a clinically approved cancer chemopreventive agent, on the gene expression profile of the cultured cell clones. Following a three day incubation period with SeM, total RNA was extracted and the gene expression profile was evaluated using Affymetrix human HG U133A microarrays and analyzed by ViaLogy’s VMAxS® platform deploying quantum resonance interferometry (QRI) processing. The differentially expressed genes and corresponding biological processes were compared across the different treatments and cells types. Whereas SeM significantly affected RNA-DNA metabolism, and protein transport and metabolism in all of the cell types evaluated, other effects by SeM were observed only in certain cell clones.
Folate and related micronturients may affect colorectal cancer (CRC) risk, but the molecular mechanism(s) remain incompletely defined. We analyzed associations between dietary folate, vitamin B6, vitamin B12 and methionine with incident CRC, overall and by microsatellite instability (MSS/MSI-L or MSI-H), CpG island methylator phenotype (CIMP-negative or CIMP-positive), BRAF mutation (negative or positive), and KRAS mutation (negative or positive) status in the prospective, population-based Iowa Women’s Health Study (IWHS; 55–69 years at baseline; n = 41,836). Intake estimates were obtained from baseline, self-reported food frequency questionnaires. Molecular marker data were obtained for 514 incident CRC cases. Folate intake was inversely associated with overall CRC risk in age-adjusted Cox regression models, while methionine intake was inversely associated with overall CRC risk in multivariable-adjusted models (RR = 0.81; 95% CI = 0.69–0.95; p trend = 0.001 and RR = 0.72; 95% CI = 0.54–0.96; p trend = 0.03 for highest versus lowest quartiles, respectively). None of the dietary exposures were associated with MSI, CIMP, BRAF, or KRAS defined CRC subtypes. These data provide minimal support for major effects from the examined micronutrients on overall or molecularly defined CRC risks in the IWHS cohort.
Colorectal Cancer; Alcohol; Older Women; Cohort Study
The objectives of the present study were to characterize γ -ray, 1 GeV/n proton, and 1 GeV/n iron ion radiation-induced adverse biological effects in terms of toxicity and transformation of HTori-3 human thyroid epithelial cells; to evaluate the ability of L-selenomethionine (SeM) to protect against radiation-induced transformation when present at different times during the assay period; and to evaluate the tumorigenicity of HTori-3 cells derived from anchorage-independent colonies following iron ion radiation exposure. Cell survival was determined by a clonogenic assay, transformation was measured by a soft agar colony formation assay, and the tumorigenic potential of the cells was determined by injecting them subcutaneously into athymic nude mice and monitoring tumor formation. The results demonstrate that exposure of HTori-3 cells to γ -ray, proton, or iron ion radiation resulted in decreased clonogenic survival, which persisted for weeks after the radiation exposure. Treatment with SeM initiated up to 7 days after the radiation exposure conferred significant protection against radiation-induced anchorage-independent growth. HTori-3 cells derived from all evaluated anchorage-independent colonies formed tumors when injected into athymic nude mice, indicating that these cells are tumorigenic and that anchorage-independent colony growth is a reliable surrogate endpoint biomarker for the radiation-induced malignant transformation of HTori-3 cells.
One of the hypothesized protective mechanisms of soy against breast cancer involves changes in estrogen metabolism to 2-hydroxy (OH) and 16α-OH estrogens. The current analysis examined the effect of soy foods on the 2:16α-OH E1 ratio among premenopausal women during a randomized, crossover intervention study; women were stratified by equol producer status, a characteristic thought to enhance the protective effects of soy isoflavones. The study consisted of a high-soy diet with 2 soy food servings/day and a low-soy diet with <3 servings of soy/week for 6 months each; estrogen metabolites were measured in 3 overnight urines (baseline and at the end of the low- and high-soy diet) using gas chromatography mass spectrometry for the 82 women who completed the study. Urinary isoflavonoids were assessed by liquid chromatography mass spectrometry. When applying mixed models, the 2:16α-OH E1 ratio increased (p=0.05) due to a non-significant decrease in 16α-OH E1 (p=0.21) at the end of high-soy diet. Similar non-significant increases in the 2:16α-OH E1 ratio were observed in equol producers (p=0.13) and non-producers (p=0.23). These findings suggest a beneficial influence of soy foods on estrogen metabolism regardless of equol producer status.
Breast cancer risk; diet and nutrition; estrogen metabolites; isoflavones; soy foods
The relationship between serological levels of iron, vitamins A, B2, C, E, zinc, thiamin, and glutathione (GSH) and the risk of oral cavity cancer was examined in a hospital-based case-control study. The case group included 65 patients with incident histologically-confirmed oral cancer and 13 patients with oral premalignancies, and the control group included 85 sex- and age-matched subjects without cancer attending the hospital dental clinic. Compared to the lowest tertiles, significant decreased risks were observed for the highest tertile of free iron (odds ratio [OR] = 0.3, 95% CI: 0.1,0.6) and transferrin saturation (iron/total iron binding capacity (TIBC) × 100) (OR= 0.4, 95% CI: 0.2,0.9). The OR for TIBC, which measures the concentration of the iron delivery protein transferrin and is increased in iron-deficiency, was 3.2 (95% CI: 1.3,8.1). These associations were stronger in never-smokers than in ever smokers. While the levels of the iron storage protein ferritin was higher in cases, this may be attributed to disease-related inflammation or comorbidity. Significant associations of the endogenous antioxidant GSH (OR = 0.4, 95% CI: 0.1,0.9) and GSH reductase activity coefficient (indicative of riboflavin deficiency) OR = 1.6, 95% CI: 1.3,3.7) with oral cancer risk were also observed. In premalignant cases, serum iron levels were 16% higher in controls (P<0.05). These findings suggest that mild iron deficiency, as indicated by low levels free iron and transferrin and high levels of TIBC, as well as low levels of the major cellular antioxidant GSH are associated with increased risk of oral cancer.
oral cancer; micronutrients; iron; glutathione; antioxidants
Consumption of red meat, particularly well done meat, has been associated with increased prostate cancer risk. High temperature cooking methods such as grilling and barbequeing may produce heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) which are known carcinogens. We assessed the association with meat consumption and estimated HCA and PAH exposure in a population-based case-control study of prostate cancer. Newly diagnosed cases aged 40–79 years (531 advanced cases, 195 localized cases) and 527 controls were asked about dietary intake, including usual meat cooking methods and doneness levels. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using multivariate logistic regression. For advanced prostate cancer, but not localized disease, increased risks were associated with higher consumption of hamburgers (OR=1.79. CI=1.10–2.92), processed meat (OR=1.57, CI=1.04, 2.36), grilled red meat (OR=1.63, CI=0.99–2.68), and well done red meat (OR=1.52, CI=0.93–2.46), and intermediate intake of 2-amino-1-methyl1-6-phenylimidazo[4,5-b]pyridine (PhIP) (quartile 2 vs. 1: OR=1.41, CI=0.98–2.01; quartile 3 vs. 1: OR=1.42, CI=0.98–2.04), but not for higher intake. White meat consumption was not associated with prostate cancer. These findings provide further evidence that consumption of processed meat and red meat cooked at high temperature is associated with increased risk of advanced, but not localized prostate cancer.
Cooking methods; heterocyclic amines; processed meat; prostate cancer; red meat
Intake of omega-3 and omega-6 fatty acids may modify the risk of basal and squamous cell carcinoma of the skin (BCC and SCC), but population-based evidence is limited and inconsistent. We examined prospectively associations between intake of omega-3 and omega-6 fatty acids estimated from food frequency questionnaires and BCC and SCC incidence among 1322 randomly selected adults in Nambour, Australia. Relative risks (RR) and 95% confidence intervals (CI) were estimated based on histologically confirmed tumors diagnosed between 1997 and 2007. Incidence of BCC was lowest in the middle third of both total omega-6 intake (RRmv.adj = 0.74, 95% CI = 0.56–0.97) and linoleic acid intake (RRmv.adj = 0.75, 95% CI = 0.57–0.99) compared with the lowest third of intake. Evidence for associations with SCC was weak, though persons with arachidonic acid intake in the middle third had a marginally increased risk of SCC (RRmv.adj = 1.42, 95% CI = 1.00–2.02). Consumption of omega-3 fatty acids was not associated with subsequent skin cancer risk. Suggestion that intake of arachidonic acid may be associated with increased SCC incidence and total omega-6 with reduced BCC from our study is still highly uncertain and may be due to chance. These data do not support an association between these fatty acids and risk of BCC or SCC.
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Previous observational studies suggest that vitamin C may reduce risk of colorectal cancer. Vitamin C transport is facilitated by membrane bound sodium-dependent transporters, SVCT1 (encoded by SLC23A1) and SVCT2 (encoded by SLC23A2). To investigate if common genetic variants in these two genes are associated with risk of colorectal tumor development, we conducted a case-control study of 656 Caucasian advanced distal colorectal adenoma cases and 665 Caucasian sigmoidoscopy-negative controls nested within the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. The analysis of common single nucleotide polymorphisms in SLC23A1 revealed no association. For SLC23A2, overall, there was no association with haplotypes, but two SNPs located inintron 8 and exon 11 could be associated (odds ratio = 0.49, 95% confidence interval = 0.25–0.95 for haplotype G-C vs. haplotype C-C). The findings should be confirmed in follow-up studies, and further investigation is required to probe the functional basis of this finding.
There is considerable biologic plausibility to the hypothesis that genetic variability in pathways involved in insulin signaling and energy homeostasis may modulate dietary risk associated with colorectal cancer. We utilized data from 2 population-based case-control studies of colon (n = 1,574 cases, 1,970 controls) and rectal (n = 791 cases, 999 controls) cancer to evaluate genetic variation in candidate SNPs identified from 9 genes in a candidate pathway: PDK1, RP6KA1, RPS6KA2, RPS6KB1, RPS6KB2, PTEN, FRAP1 (mTOR), TSC1, TSC2, Akt1, PIK3CA, and PRKAG2 with dietary intake of total energy, carbohydrates, fat, and fiber. We employed SNP, haplotype, and multiple-gene analysis to evaluate associations. PDK1 interacted with dietary fat for both colon and rectal cancer and with dietary carbohydrates for colon cancer. Statistically significant interaction with dietary carbohydrates and rectal cancer was detected by haplotype analysis of PDK1. Evaluation of dietary interactions with multiple genes in this candidate pathway showed several interactions with pairs of genes: Akt1 and PDK1, PDK1 and PTEN, PDK1 and TSC1, and PRKAG2 and PTEN. Analyses show that genetic variation influences risk of colorectal cancer associated with diet and illustrate the importance of evaluating dietary interactions beyond the level of single SNPs or haplotypes when a biologically relevant candidate pathway is examined.
Ascorbic acid (vitamin C) inhibits cancer cell growth and there is a controversy regarding the cancer chemoprotective effects of pharmacologic doses of this compound which exhibits pro-oxidant activity. We hypothesized that the anticancer activity of pharmacologic doses of ascorbic acid (< 5 mM) is due, in part, to reactive oxygen species (ROS)-dependent downregulation of specificity protein (Sp) transcription factors Sp1, Sp3 and Sp4 and Sp-regulated genes. In this study, ascorbic acid (1 – 3 mM) decreased RKO and SW480 colon cancer cell proliferation and induced apoptosis and necrosis and this was accompanied by downregulation of Sp1, Sp3 and Sp4 proteins. In addition, ascorbic acid decreased expression of several Sp-regulated genes that are involved in cancer proliferation [hepatocyte growth factor receptor (c-Met), epidermal growth factor receptor (EGFR) and cyclin D1], survival (survivin and bcl-2), and angiogenesis [vascular endothelial growth factor (VEGF) and its receptors (VEGFR1 and VEGFR2)]. Other pro-oxidants such as hydrogen peroxide exhibited similar activities in colon cancer cells and cotreatment with glutathione inhibited these responses. This study demonstrates for the first time that the anticancer activities of ascorbic acid are due, in part, to ROS-dependent repression of Sp transcription factors.
Ascorbic acid; colon cancer; ROS; peroxide; Sp downregulation
Colorectal cancer (CRC) is a leading cause of cancer death in the United States. The majority of CRC arise in adenomatous polyps and 25–35% of colon adenoma risk could be avoidable by modifying diet and lifestyle habits. We assessed the association between diet and the risk of self-reported physician-diagnosed colorectal polyps among 2,818 subjects who had undergone colonoscopy. Subjects participated in 2 cohort studies: the AHS-1 in 1976 and the AHS-2 from 2002–2005. Multivariate logistic regression analysis was used to estimate the period risk of incident cases of polyps; 441 cases of colorectal polyps were identified. Multivariate analysis adjusted by age, sex, body mass index, and education showed a protective association with higher frequency of consumption of cooked green vegetables (OR 1 time/d vs. <5/wk = 0.76, 95% CI = 0.59–0.97) and dried fruit (OR 3+ times/wk vs. <1 time/wk = 0.76, 95%CI = 0.58–0.99). Consumption of legumes at least 3 times/wk reduced the risk by 33% after adjusting for meat intake. Consumption of brown rice at least 1 time/wk reduced the risk by 40%. These associations showed a dose-response effect. High frequency of consumption of cooked green vegetables, dried fruit, legumes, and brown rice was associated with a decreased risk of colorectal polyps.
The balance of putative pro- and anti-inflammatory lipoxygenase (LOX)-derived S-hydroxyeicosatetraenoic acids (S-HETEs) in colon mucosa is a potential target for modulating colon cancer risk and progression. The biological effects of S-HETEs and R-HETEs (produced by distinct pathways) may differ, but levels of these compounds in colon are unknown. The objective of this study was to develop chiral methods to characterize HETE enantiomers in colonic mucosa and evaluate the effects of fish oil on HETE formation. C57BL/6 mice (COX-1 null, COX-2 null, wild-type) were fed a diet supplemented with either olive oil or menhaden oil for 11 weeks, and R/S-HETEs in colonic mucosa were quantified by chiral LC-MS/MS. The R-enantiomer comprised 60-72% of 5-HETE, 18-58% of 15-HETE and 1-16% of 12-HETE in colonic mucosa, suggesting that non-LOX sources contribute to HETE profiles. Fish oil reduced levels of both R- and S-HETEs, and increased the preponderance of the R-enantiomers (particularly 12- and 15-HETEs). There was apparent shunting of arachidonic acid to12/15-LOX in the COX-1 null animals. This is the first report of the enantiomeric composition of HETEs in the colon in vivo.
experimental; lipoxygenase; hydroxyeicosatetraenoic acid; enantiomer; colon
We prospectively investigated whether coffee consumption was associated with decreased risk of colorectal cancer and whether cigarette smoking and stage of disease modify the association in the Singapore Chinese Health Study. During the first 12 years of follow-up, 961 colorectal cancer cases occurred in the cohort of over 60,000 middle-aged or older Chinese men and women living in Singapore. Baseline dietary exposures were assessed through in-person interviews using a validated food frequency questionnaire. The relation between coffee consumption and colorectal cancer risk was assessed by proportional hazards (Cox) regression. No overall association between coffee intake and colorectal cancer was observed. However, in analysis by subsite and stage restricted to ever smokers, the coffee–colon cancer association became statistically significant for advanced disease (P for trend = 0.01). The hazard ratio was 0.56 (95% confidence interval = 0.35–0.90) for advanced colon cancer in drinkers of 2 or more cups per day compared with those who drank no coffee or less than 1 cup per day. Although there is a null association between coffee intake and risk of colorectal cancer overall, coffee may protect against smoking related advanced colon cancer.
In the Women’s Health Initiative (WHI) trial of calcium plus vitamin D (CaD), we examined the treatment effect on incidence and mortality for all invasive cancers. Postmenopausal women (N = 36,282) were randomized to 1,000 mg of elemental calcium with 400 IU vitamin D3 or placebo. Cox models estimated risk of cancer incidence and mortality. After 7.0 yr, 1,306 invasive cancers were diagnosed in the supplement and 1,333 in the placebo group [hazard ratio (HR) = 0.98; CI = 0.90, 1.05, unweighted P = 0.54]. Mortality did not differ between supplement (315, annualized% = .26) and placebo [(347, 0.28%; P = 0.17; HR = 0.90 (0.77, 1.05)]. Significant treatment interactions on incident cancer were found for family history of cancer, personal total intake of vitamin D, smoking, and WHI dietary trial randomized group. Calcium/vitamin D supplementation did not reduce invasive cancer incidence or mortality. Supplementation lowered cancer risk in the WHI healthy diet trial arm and in women without a first-degree relative with cancer. The interactions are only suggestive given multiple testing considerations. The low vitamin D dose provided, limited adherence, and lack of serum 25(OH)D values should be considered when interpreting these findings.
Ingested nitrate can be endogenously reduced to nitrite, which may form N-nitroso compounds, known potent carcinogens. However, some studies have reported no or inverse associations between dietary nitrate intake and cancer risk. These associations may be confounded by a protective effect of folate, which plays a vital role in DNA repair. We evaluated the interaction of dietary and water nitrate intake with total folate intake on breast cancer risk in the Iowa Women’s Health Study. Dietary intake was assessed at study baseline. Nitrate intake from public water was assessed using a historical database on Iowa municipal water supplies. After baseline exclusions, 34,388 postmenopausal women and 2,875 incident breast cancers were included. Overall, neither dietary nor water nitrate was associated with breast cancer risk. Among those with folate intake ≥400 μg/d, breast cancer risk was significantly increased in public water users with the highest nitrate quintile (HR=1.40, 95%CI=1.05–1.87) and private well users (HR=1.38, 95%CI=1.05–1.82) compared to public water users with the lowest nitrate quintile; in contrast, there was no association among those with lower folate intake. Our findings do not support a previous report of increased risk of breast cancer among individuals with high dietary nitrate but low folate intake.
nitrate; folate; interaction; breast cancer; epidemiological
Prostate cancer is a common but complex disease, and distinguishing modifiable risk factors such as diet for more aggressive disease is extremely important. Previous work has detected intriguing associations between vegetable, fruit, and grains and more aggressive prostate cancer, although these remain somewhat unclear. Here we further investigate such potential relationships with a case-control study of 982 men (470 more aggressive prostate cancer cases and 512 control subjects). Comparing the highest to lowest quartiles of intake, we found that increasing intakes of leafy vegetables were inversely associated with risk of aggressive prostate cancer (adjusted odds ratio (OR) =0.66, 95% CI: 0.46, 0.96, P-trend=0.02), as was higher consumption of high carotenoid vegetables (OR=0.71, 95% CI: 0.48, 1.04; P-trend=0.04). Conversely, increased consumption of high glycemic index foods were positively associated with risk of aggressive disease (OR=1.64, 95% CI: 1.05, 2.57; P-trend=0.02). These results were driven by a number of specific foods within the food groups. Our findings support the hypothesis that diets high in vegetables and low in high glycemic index foods decrease risk of aggressive prostate cancer.
Diet; aggressive prostate cancer
We investigated whether serum from normal weight women is less mitogenic and more apoptotic than sera from the same women in the overweight state. Sera from premenopausal women, age (mean ±SEE) 34.6±0.53 years, who were randomized to caloric restriction (CR) (n=13), CR + aerobic exercise (AE) (n=14) or CR + resistance training (RT) (n=20) were used to culture endometrial cancer cells. Phases of the cell cycle were determined, proliferating cell nuclear antigen (PCNA) positivity was used to assess proliferation and apoptosis was assessed by determining cleaved caspase-3 and poly-ADP-ribose polymerase (PARP). Analyses showed that overall, cells grown in sera from the weight-reduced state had significantly more cells in G0/G1 and significantly fewer cells in the S and G2/M phases of the cell cycle than cells grown in sera from the overweight state. PCNA staining confirmed that cells grown in sera from the weight-reduced state had fewer proliferating cells. Cleaved caspase-3 and PARP were not different in cells grown in sera from the weight-reduced state compared to the overweight state. We conclude that weight loss with or without exercise could lower the risk for cancer through changes in serum that result in reduced cellular mitogenicity.
High doses of niacin (nicotinic acid) used to treat dyslipidemias cause flushing, due to high levels of prostaglandin D2 (PGD2). GPR109A, a G-protein coupled receptor, triggers the flushing in the skin. In addition to boosting PGD2, niacin binding to GPR109A activates the entire prostanoid cascade. We found that GPR109A occurs throughout the gastrointestinal tract. Mice that alternated between a 1% niacin diet and a control diet had higher urinary prostaglandin E2 (PGE2) metabolite levels when on niacin (2.8-fold increase; 95% confidence interval, 1.8–3.9). PGE2 promotes tumors in the intestines, whereas PGD2 may have an opposite effect, on the basis of our report showing that transgenic hematopoietic prostaglandin D synthase suppresses intestinal adenomas in ApcMin/+ mice. To determine if either tumor growth or tumor suppression prevails, we fed ApcMin/+ mice a 1% niacin diet and assessed tumor development. A 1% niacin diet did not affect the number of tumors scored histologically in ApcMin/+ mice at 14 weeks (33 mice on niacin, 33 controls). Although niacin stimulates production of various prostaglandins, our results support an interpretation that very high intakes of niacin are safe in relation to intestinal tumors in this model.
niacin; colorectal cancer; animal models; eicosanoids/prostaglandins
Moringa oleifera Lamarack is commonly consumed for nutritional or medicinal properties. We recently reported the isolation and structure elucidation of novel bioactive phenolic glycosides, including 4-[(2′-O-acetyl-α-l-rhamnosyloxy)benzyl]isothiocyanate (RBITC), which was found to suppress inducible nitric oxide synthase (iNOS) expression and nitric oxide production in lipopolysaccharide-stimulated RAW 264.7 mouse macrophage cells. Inhibitors of proteins such as cyclooxygenase-2 (COX-2) and iNOS are potential anti-inflammatory and cancer chemopreventive agents. The inhibitory activity of RBITC on NO production (IC50 = 0.96 ± 0.23 µM) was greater than that mediated by other well-known isothiocyanates such as sulforaphane (IC50 = 2.86 ± 0.39 µM) and benzyl isothiocyanate (IC50 = 2.08 ± 0.28 µM). RBITC inhibited expression of COX-2 and iNOS at both the protein and mRNA levels. Major upstream signaling pathways involved mitogen-activated protein kinases and nuclear factor-κB (NF-κB). RBITC inhibited phosphorylation of extracellular signal regulated kinase and stress-activated protein kinase, as well as ubiquitin-dependent degradation of inhibitor κBα (IκBα). In accordance with IκBα degradation, nuclear accumulation of NF-κB, and subsequent binding to NF-κB cis-acting element, was attenuated by treatment with RBITC. These data suggest RBITC should be included in the dietary armamentarium of isothiocyanates potentially capable of mediating anti-inflammatory or cancer chemopreventive activity.
cancer prevention; nitric oxide; cell signaling; in vitro/cell culture; isothiocyanates
Trans-resveratrol, present in high concentration in the skin of red grapes and red wine, has a dose-dependent antiproliferative effect in vitro, prevents the formation of mammary tumors, and has been touted as a chemopreventive agent. Based upon in vitro studies demonstrating that trans-resveratrol downregulates the expression of 1) DNA methyltransferases and 2) the cancer promoting prostaglandin (PG)E2, we determined if trans-resveratrol had a dose-related effect on DNA methylation and prostaglandin expression in humans. Thirty-nine adult women at increased breast cancer risk were randomized in double-blind fashion to placebo, 5 or 50 mg trans-resveratrol twice daily for 12 wk. Methylation assessment of 4 cancer-related genes (p16, RASSF-1α, APC, CCND2) was performed on mammary ductoscopy specimens. The predominant resveratrol species in serum was the glucuronide metabolite. Total trans-resveratrol and glucuronide metabolite serum levels increased after consuming both trans-resveratrol doses (P < .001 for both). RASSF-1α methylation decreased with increasing levels of serum trans-resveratrol (P = .047). The change in RASSF-1α methylation was directly related to the change in PGE2 (P = .045). This work provides novel insights into the effects of trans-resveratrol on the breast of women at increased breast cancer risk, including a decrease in methylation of the tumor suppressor gene RASSF-1α. Because of the limited sample size, our findings should be validated in a larger study.
No studies have investigated dietary differences between head and neck squamous cell carcinoma (HNSCC) patients with human papillomavirus (HPV)-positive tumors and patients with HPV-negative tumors. This study was designed to investigate the relationship between diet and HPV status in HNSCC patients. Cases of HNSCC were recruited from 2 clinical centers participating in the University of Michigan Head and Neck Specialized Program of Research Excellence (SPORE). HPV tissue genotyping was performed, and epidemiological and dietary data collected. Multivariable logistic regression tested whether pretreatment consumption of 12 selected micronutrients was significantly associated with HPV-positive status in 143 patients newly diagnosed with cancer of the oral cavity or pharynx. After controlling for age, sex, body mass index, tumor site, cancer stage, problem drinking, smoking, and energy intake, significant and positive associations were observed between vitamin A, vitamin E, iron, β-carotene, and folate intake and HPV-positive status (Ptrend < 0.05), suggesting that diet may be a factor in the improved prognosis documented in those with HPV-positive HNSCC. Dietary differences by HPV status should be considered in prognostic studies to better understand the influence of diet on HNSCC survival.
We determined if soy isoflavones have dose-related estrogenic and methylation effects. Thirty-four healthy premenopausal women were randomized to 40 mg or 140 mg isoflavones daily through one menstrual cycle. Breast specific and systemic estrogenic effects were assessed measuring the estrogenic marker complement (C)3 and changes in cytology, whereas methylation assessment of 5 cancer related genes (p16, RASSF1A, RARβ2, ER, and CCND2) was performed on intraductal specimens. Serum genistein significantly increased after consuming both isoflavone doses. Cytology did not significantly change at either isoflavone dose. Serum C3 levels posttreatment were inversely related to change in serum genistein (r = −0.76, P = 0.0045) in women consuming low but not high dose isoflavones. The RARβ2 hypermethylation increase posttreatment correlated with the posttreatment genistein level considering the entire group (r 0.67, P = 0.0017) and those receiving high-dose isoflavones (r = 0.68, P = 0.021). At the low but not the high isoflavone dose, CCND2 hypermethylation increase correlated with posttreatment genistein levels (r = 0.79, P = 0.011). In summary, the inverse correlation between C3 and genistein suggests an antiestrogenic effect. Isoflavones induced dose-specific changes in RARβ2 and CCND2 gene methylation, which correlated with genistein levels. This work provides novel insights into estrogenic and methylation effects of dietary isoflavones.
Insulin-like growth factor 1 (IGF-1) is an anabolic hormone important for growth and development. However, high-circulating serum concentrations in adults are associated with increased risk of postmenopausal breast cancer. Nutritional status and specific foods influence serum IGF-1 concentrations. Breast cancer incidence is typically low in Asian countries where soy is commonly consumed. Paradoxically, soy supplement trials in American women have reported significant increases in IGF-1. Seaweed also is consumed regularly in Asian countries where breast cancer risk is low. We investigated the possibility that seaweed could modify soy-associated increases in IGF-1 in American women. Thirty healthy postmenopausal women (mean age 58 yr) participated in this 14-wk double-blinded, randomized, placebo-controlled crossover clinical trial. Participants consumed 5 g/day placebo or seaweed (Alaria esculenta) in capsules for 7 wk. During the 7th wk, a high-soy protein isolate powder was added (2 mg/kg body weight aglycone equivalent isoflavones). Overnight fasting blood samples were collected after each intervention period. Soy significantly increased serum IGF-1 concentrations compared to the placebo (21.2 nmol/L for soy vs. 16.9 nmol/L for placebo; P = 0.0001). The combination of seaweed and soy significantly reduced this increase by about 40% (21.2 nmol/L for soy alone vs. 19.4 nmol/L; P = 0.01). Concurrent seaweed and soy consumption may be important in modifying the effect of soy on IGF-1 serum concentrations.