Influence of dietary calcium and vitamin D on diet-induced epithelial cell hyperproliferation in mice

Association of Domestic Water Hardness with All-Cause and Cause-Specific Cancers: Evidence from 447,996 UK Biobank Participants

BACKGROUND

Accumulating evidence suggests that domestic water hardness is linked to health outcomes, but its association to all-cause and cause-specific cancers warrants investigation.

OBJECTIVE

The aim of this study was to investigate the association of domestic hard water with all-cause and cause-specific cancers.

METHODS

In the prospective cohort study, a total of 447,996 participants from UK Biobank who were free of cancer at baseline were included and followed up for 16 y. All-cause and 22 common cause-specific cancer diagnoses were ascertained using hospital inpatient records and self-reported data until 30 November 2022. Domestic water hardness, measured by CaCO 3 concentrations, was obtained from the local water supply companies across England, Scotland, and Wales in 2005. Data were analyzed using Cox proportional hazard models, with adjustments for known measured confounders, including demographic, socioeconomic, clinical, biochemical, lifestyle, and environmental factors.

RESULTS

Over a median follow-up of 13.6 y (range: 12.7-14.4 y), 58,028 all-cause cancer events were documented. A U-shaped relationship between domestic water hardness and all-cause cancers was observed (p for nonlinearity < 0.001 ). In comparison with individuals exposed to soft water (0 - 60 mg / L ), the hazard ratios (HRs) and 95% confidence intervals (CIs) of all-cause cancer were 1.00 (95% CI: 0.98, 1.02) for those exposed to moderate hard water (> 60 - 120 mg / L ), 0.88 (95% CI: 0.84, 0.91) for those exposed to hard water (> 120 - 180 mg / L ) and 1.06 (95% CI: 1.04, 1.08) for those exposed to very hard water (> 180 mg / L ). Additionally, domestic water hardness was associated with 11 of 22 cause-specific cancers, including cancers of the esophagus, stomach, colorectal tract, lung, breast, prostate, and bladder, as well as non-Hodgkin lymphoma, multiple myeloma, malignant melanoma, and hematological malignancies. Moreover, we observed a positive linear relationship between water hardness and bladder cancer.

DISCUSSION

Our findings suggest that domestic water hardness was associated with all-cause and multiple cause-specific cancers. Findings from the UK Biobank support a potentially beneficial association between hard water and the incidence of all-cause cancer. However, very hard water may increase the risk of all-cause cancer. https://doi.org/10.1289/EHP13606.

Association between calcium intake and risk of breast cancer: An updated systematic review and dose-response meta-analysis of cohort studies

BACKGROUND

Prospective cohort studies that dietary or total calcium intake was considered as the exposure variable and risk of BC as the main or second outcome were included in this systematic review.

METHODS

We searched the online databases of PubMed, Web of science, Scopus and, Google scholar for relevant studies published up to November 2021, using relevant keywords. Seven cohort studies including 1,579,904 participants, were eligible for the current meta-analysis.

RESULTS

Pooled effect size for the highest versus lowest category indicated that increasing dietary calcium intake was significantly associated with a reduced risk of BC (RR, 0.90; 95% CI: 0.81-1.00). However, total calcium intake revealed a non-significant inverse association (RR, 0.97; 95%CI, 0.91-1.03). Dose-response meta-analysis showed that every additional 350 mg per day dietary (RR, 0.94; 95% CI, 0.89-0.99) and total calcium intake (RR, 0.99; 95% CI, 0.97-1.00) was significantly associated with a lower risk of BC. Also, a significant decreasing trend for the risk of BC was observed after 500 mg/d of dietary calcium intake (P-nonlinearity = 0.05, n = 6.

CONCLUSION

Finally, our dose-response meta-analysis revealed a 6 and 1% lower risk of BC in each 350 mg per day increment in dietary and total calcium intake, respectively.

Milk Intake in Early Life and Later Cancer Risk: A Meta-Analysis

Dairy consumption in adulthood has been demonstrated to influence cancer risk. Although childhood and adolescence represent critical periods of rapid growth, the relationship between milk intake in early life and later cancer risk is unclear. Thus, we examined this relationship by conducting a meta-analysis of the observational studies. PubMed and Embase were searched for relevant articles that were published throughout December 2021. The summary relative risk (RR) and 95% confidence interval (CI) were estimated using the DerSimonian-Laird random-effects model. The summary RR for the highest vs. lowest milk intake was 0.83 (95% CI = 0.69–1.00; p = 0.05; I² = 60%; seven studies) for breast cancer, 0.98 (95% CI = 0.72–1.32; p = 0.88; I² = 51%; four studies) for prostate cancer, and 0.90 (95% CI = 0.42–1.93; p = 0.78; I² = 83%; three studies) for colorectal cancer. No evidence of an association emerged in subgroup analyses of menopausal status, cancer stage, fat content of milk, life stage of milk intake, or study design. Consistent results were observed in the meta-analyses using total dairy intake. In conclusion, milk intake during childhood and adolescence might not be associated with risks of breast, prostate, and colorectal cancer later in life. Given the small number of studies that were included in our meta-analysis, and the high heterogeneity, more studies are warranted for a definitive conclusion.

Dairy foods, calcium, and risk of breast cancer overall and for subtypes defined by estrogen receptor status: a pooled analysis of 21 cohort studies

BACKGROUND

Epidemiologic studies examining the relations between dairy product and calcium intakes and breast cancer have been inconclusive, especially for tumor subtypes.

OBJECTIVE

To evaluate the associations between intakes of specific dairy products and calcium and risk of breast cancer overall and for subtypes defined by estrogen receptor (ER) status.

METHOD

We pooled the individual-level data of over 1 million women who were followed for a maximum of 8-20 years across studies. Associations were evaluated for dairy product and calcium intakes and risk of incident invasive breast cancer overall (n = 37,861 cases) and by subtypes defined by ER status. Study-specific multivariable hazard ratios (HRs) were estimated and then combined using random-effects models.

RESULTS

Overall, no clear association was observed between the consumption of specific dairy foods, dietary (from foods only) calcium, and total (from foods and supplements) calcium, and risk of overall breast cancer. Although each dairy product showed a null or very weak inverse association with risk of overall breast cancer (P, test for trend >0.05 for all), differences by ER status were suggested for yogurt and cottage/ricotta cheese with associations observed for ER-negative tumors only (pooled HR = 0.90, 95% CI: 0.83, 0.98 comparing ≥60 g/d with <1 g/d of yogurt and 0.85, 95% CI: 0.76, 0.95 comparing ≥25 g/d with <1 g/d of cottage/ricotta cheese). Dietary calcium intake was only weakly associated with breast cancer risk (pooled HR = 0.98, 95% CI: 0.97, 0.99 per 350 mg/d).

CONCLUSION

Our study shows that adult dairy or calcium consumption is unlikely to associate with a higher risk of breast cancer and that higher yogurt and cottage/ricotta cheese intakes were inversely associated with the risk of ER-negative breast cancer, a less hormonally dependent subtype with poor prognosis. Future studies on fermented dairy products, earlier life exposures, ER-negative breast cancer, and different racial/ethnic populations may further elucidate the relation.

Dietary calcium, vitamin D, and breast cancer risk in women: findings from the SUN cohort

PURPOSE

Epidemiological evidence concerning the relationship between calcium and vitamin D intake and breast cancer (BC) is inconclusive. Moreover, the association according to menopausal status remains unclear. We aimed to assess whether total intakes from dietary and supplemental sources of calcium and vitamin D were associated with the incidence of BC in a Mediterranean cohort.

METHODS

We prospectively evaluated the association between intakes of calcium and vitamin D and BC risk among 10,812 women in the Seguimiento Universidad de Navarra (SUN) Project, a Spanish cohort of university graduates.

RESULTS

During a mean follow-up of 10.7 years, 101 incident BC cases were confirmed. Evidence of a non-linear association between total calcium intake and BC risk was found (P_{non-linearity} = 0.011) with risk reductions associated with higher intake up to approximately 1400 mg/day. Moderate intake [Tertile 2 (T2)] of total calcium was associated with lower overall BC risk [HR for T2 vs. Tertile 1 (T1): 0.55; 95% CI 0.33-0.91] and also among postmenopausal women (HR_{T2 vs. T1} = 0.38; 95% CI 0.16-0.92). Intake of vitamin D was not associated with BC risk.

CONCLUSIONS

Our findings suggest an L-shaped association between total calcium intake and BC incidence. Moderate calcium intake may be associated with lower BC risk among overall and postmenopausal women, but not among premenopausal women. No evidence for any association between vitamin D intake and BC was found. Adherence to current guidelines recommendations for calcium intake may help to reduce BC risk.

Nutritional Regulation of Mammary Gland Development and Milk Synthesis in Animal Models and Dairy Species

In mammals, milk is essential for the growth, development, and health. Milk quantity and quality are dependent on mammary development, strongly influenced by nutrition. This review provides an overview of the data on nutritional regulations of mammary development and gene expression involved in milk component synthesis. Mammary development is described related to rodents, rabbits, and pigs, common models in mammary biology. Molecular mechanisms of the nutritional regulation of milk synthesis are reported in ruminants regarding the importance of ruminant milk in human health. The effects of dietary quantitative and qualitative alterations are described considering the dietary composition and in regard to the periods of nutritional susceptibly. During lactation, the effects of lipid supplementation and feed restriction or deprivation are discussed regarding gene expression involved in milk biosynthesis, in ruminants. Moreover, nutrigenomic studies underline the role of the mammary structure and the potential influence of microRNAs. Knowledge from three lactating and three dairy livestock species contribute to understanding the variety of phenotypes reported in this review and highlight (1) the importance of critical physiological stages, such as puberty gestation and early lactation and (2) the relative importance of the various nutrients besides the total energetic value and their interaction.

Vitamin D Levels in Patients with Colorectal Cancer Before and After Treatment Initiation

PURPOSE

We aimed to described 25-hydroxyvitamin D [25(OH)D] levels in newly diagnosed colorectal cancer (CRC) patients and to re-evaluate levels after chemotherapy.

METHODS

Permanent residents of the San Francisco Bay Area with a new CRC diagnosis of any stage were recruited prior to any non-surgical therapy. Serum 25(OH)D levels were measured at time of diagnosis and 6-month follow-up. Supplement use was not restricted. The primary endpoint was the frequency of vitamin D deficiency in patients with newly diagnosed CRC of all stages. The Kruskal-Wallis and Spearman correlation tests were used to evaluate associations of patient characteristics with 25(OH)D levels.

RESULTS

Median 25(OH)D level at baseline was 27.0 ng/mL (range 7.2, 59.0); 65% of patients had insufficient levels (25(OH)D < 30 ng/mL) (n = 94). Race, disease stage, multivitamin use, vitamin D supplementation, and county of residence were associated with baseline 25(OH)D levels (P < 0.05). The median change in 25(OH)D from baseline to 6 months was - 0.7 ng/mL [- 19.4, 51.7] for patients treated with chemotherapy (n = 58) and 1.6 ng/mL [- 6.4, 33.2] for patients who did not receive chemotherapy (n = 19) (P = 0.26). For patients who received vitamin D supplementation during chemotherapy, the median 25(OH)D change was 8.3 ng/mL [- 7.6, 51.7] versus - 1.6 [- 19.4, 24.3] for chemotherapy patients who did not take vitamin D supplements (P = 0.02).

CONCLUSION

Among patients with a new diagnosis of CRC, most patients were found to have 25(OH)D levels consistent with either deficiency or insufficiency. In the subset of patients who received chemotherapy and took a vitamin D supplement, serum 25(OH)D levels increased, suggesting that vitamin D repletion is a feasible intervention during chemotherapy.

Pubertal mammary development as a "susceptibility window" for breast cancer disparity

Factors such as socioeconomic status, age at menarche and childbearing patterns are components that have been shown to influence mammary gland development and establish breast cancer disparity. Pubertal mammary gland development is selected as the focus of this review, as it is identified as a "window of susceptibility" for breast cancer risk and disparity. Here we recognize non-Hispanic White, African American, and Asian American women as the focus of breast cancer disparity, in conjunction with diets associated with changes in breast cancer risk. Diets consisting of high fat, N-3 polyunsaturated fatty acids, N-6 polyunsaturated fatty acids, as well as obesity and the Western diet have shown to lead to changes in pubertal mammary gland development in mammalian models, therefore increasing the risk of breast cancer and breast cancer disparity. While limited intervention strategies are offered to adolescents to mitigate development changes and breast cancer risk, the prominent solution to closing the disparity among the selected population is to foster lifestyle changes that avoid the deleterious effects of unhealthy diets.

The Effects of UVB and Vitamin D on Decreasing Risk of Colorectal Cancer Incidence and Mortality: A Review of the Epidemiology, Clinical Trials, and Mechanisms

The solar ultraviolet B-vitamin D-cancer hypothesis was first suggested in 1980 based on a geographical ecological study. Since then, several ecological and observational studies, as well as researches of mechanisms have supported the hypothesis. Also, the association between vitamin D condition and cancer risk has been assessed in a number of epidemiologic studies, while data from interventional studies remain scant. In regard of cancer locations, the body of evidence is most substantial for colorectal cancer, for which support comes from studies of 25(OH)D, vitamin D intake, and region of residence in a sunny weather. Collectively evidence demonstrates that vitamin D has a potent and beneficial effect at antagonizing and blocking several mitogenic mechanisms related to tumorigenesis. Taken together with the epidemiological studies and limited clinical trials, individuals may need to consider elevating 25(OH)D levels via sun exposure and/or vitamin D supplementation to decrease risk of colorectal cancer, in addition to standard care, treat cancer.

Effect of cigarette smoke exposure and mutant Kras overexpression on pancreatic cell proliferation

Pancreatic cancer is the fourth leading cause of cancer-associated mortality. The major risk factor for pancreatic cancer is cigarette smoking. Kras mutations are commonly observed in human pancreatic cancers. The present study examined the hypothesis that exposure to cigarette smoke and overexpression of a mutant Kras gene in the pancreas affects pancreatic cell proliferation in mice. Mice overexpressing the mutant Kras gene (KRas^G12D) in the pancreas as well as wild-type mice were exposed to environmental tobacco smoke for 2 weeks. Overexpression of mutant Kras increased cell proliferation in pancreatic ductal, acinar and islet cells. Notably, cigarette smoke exposure decreased cell proliferation in pancreatic ductal and acinar cells, and had no effect in islet cells. Cigarette smoke did not affect pancreatic protein levels of tumor necrosis factor (TNF)α, p53, or cyclin D₁, but mutant Kras overexpression slightly decreased TNFα and p53 protein levels. Therefore, pancreatic cell proliferation in mice overexpressing mutant Kras is associated with the later development of pancreatic tumors, but effects of cigarette smoke on pancreatic cell proliferation do not provide a good model for human pancreatic carcinogenesis.

Association of Vitamin D Receptor Gene Polymorphisms with Colorectal Cancer in a Saudi Arabian Population

BACKGROUND

Vitamin D, causally implicated in bone diseases and human malignancies, exerts its effects through binding to the vitamin D receptor (VDR). VDR is a transcription factor modulating the expression of several genes in different pathways. Genetic variants in the VDR gene have been associated with several cancers in different population including colorectal cancer.

OBJECTIVE

To assess the association of VDR gene polymorphisms in relation with colorectal cancer (CRC) in a Saudi population.

METHODS

The polymorphisms of VDR gene (BsmI, FokI, ApaI and TaqI) were analyzed by the polymerase chain reaction amplification of segments of interest followed by Sanger sequencing. One hundred diagnosed CRC patients and 100 healthy control subjects that were age and gender matched were recruited.

RESULTS

We did not observe significant association of any of the four VDR polymorphisms with colorectal cancer risk in the overall analysis. Although not statistically significant, the AA genotype of BsmI conferred about two-fold protection against CRCs compared to the GG genotype. Stratification of the study subjects based on age and gender suggests statistically significant association of CRC with the 'C' allele of ApaI in patients >57 years of age at disease diagnosis and BsmI polymorphism in females. In addition, statistically significant differences were observed for the genotypic distributions of VDR-BsmI, ApaI and TaqI SNPs between Saudi Arabian population and several of the International HapMap project populations.

CONCLUSION

Despite the absence of correlation of the examined VDR polymorphisms with CRCs in the combined analysis, ApaI and BsmI loci are statistically significantly associated with CRC in elderly and female patients, respectively. These findings need further validation in larger cohorts prior to utilizing these SNPs as potential screening markers for colorectal cancers in Saudi population.

Association between nutrient intake and thyroid cancer risk in Korean women

BACKGROUND/OBJECTIVES

The incidence of thyroid cancer has increased in many countries, including Korea. International differences in the incidence of thyroid cancer may indicate a role of diet, but findings from previous studies are inconclusive. Therefore, we aimed to investigate the roles of nutrients in thyroid cancer risk in Korean women.

SUBJECTS/METHODS

We conducted a case-control study comprising 113 cases and 226 age-matched controls. Nutrient intake was assessed using a validated food frequency questionnaire, and the association between nutrient intake and thyroid cancer risk was estimated using a logistic regression model.

RESULTS

We found that high calcium intake was associated with a reduced risk of thyroid cancer (OR [95% CI] = 0.55 [0.35-0.89]). Significant associations were observed among subjects who were older than 50 years, had low BMI, and had low calorie intake. However, other nutrients included in this study did not show any significant associations with thyroid cancer risk.

CONCLUSIONS

This study suggested a possible protective effect of calcium on thyroid cancer risk. Well-designed prospective studies are required to confirm these findings.

Early Life and Postnatal Western Diet Feeding and Susceptibility to Chemically Induced Colonic Aberrant Crypt Foci in Male Rats Offspring

The modifying effects of a Western diet (WD) during early life on the susceptibility to colon carcinogenesis induced by dimethylhydrazine (DMH) were examined in male rats as later adults. Three groups were studied: a lifetime control diet-fed group, a test group fed WD since pregnancy from dams until postnatal day (PND) 42, and a group fed WD at adulthood. At PND 70, all groups received the carcinogen DMH and were euthanized 10 wk later. Colonic aberrant crypt foci (ACF) were scored (number and crypt multiplicity) and the altered pattern of β-catenin expression was evaluated in the colonic lesions. ACF multiplicity (≥4 crypts) was significantly higher in the group fed WD at early life than in the group fed the control diet. ACF number, crypt multiplicity, and the number of high-grade dysplastic lesions were significantly higher in the group fed WD at adulthood than in the groupfed the control diet. The number of lesions with altered β-catenin expression was higher in the groups receiving WD at early life or at adulthood than in the lifetime control-diet-fed group. These findings indicate that WD exposure at early life increased the susceptibility to colon carcinogenesis at adulthood.

Calcium sensing receptor suppresses human pancreatic tumorigenesis through a novel NCX1/Ca(2+)/β-catenin signaling pathway

The calcium sensing receptor (CaSR) is functionally expressed in normal human pancreases, but its pathological role in pancreatic tumorigenesis is currently unknown. We sought to investigate the role of CaSR in pancreatic cancer (PC) and the underlying molecular mechanisms. We revealed that the expression of CaSR was consistently downregulated in the primary cancer tissues from PC patients, which was correlated with tumor size, differentiation and poor survival of the patients. CaSR activation markedly suppressed pancreatic tumorigenesis in vitro and in vivo likely through the Ca(2+) entry mode of Na(+)/Ca(2+) exchanger 1 (NCX1) to induce Ca(2+) entry into PC cells. Moreover, NCX1-mediated Ca(2+) entry resulted in Ca(2+)-dependent inhibition of β-catenin signaling in PC cells, eventually leading to the inhibition of pancreatic tumorigenesis. Collectively, we demonstrate for the first time that CaSR exerts a suppressive function in pancreatic tumorigenesis through a novel NCX1/Ca(2+)/β-catenin signaling pathway. Targeting this specific signaling pathway could be a potential therapeutic strategy for PC.

MicroRNA binding site polymorphisms as biomarkers in cancer management and research

MicroRNAs (miRNAs) are important regulators of eukaryotic gene expression. They have been implicated in a broad range of biological processes, and miRNA-related genetic alterations probably underlie several human diseases. Single nucleotide polymorphisms of transcripts may modulate the posttranscriptional regulation of gene expression by miRNAs and explain interindividual variability in cancer risk and in chemotherapy response. On the basis of recent association studies published in the literature, the present review mainly summarizes the potential role of miRNAs as molecular biomarkers for disease susceptibility, diagnosis, prognosis, and drug-response prediction in tumors. Many clues suggest a role for polymorphisms within the 3' untranslated regions of KRAS rs61764370, SET8 rs16917496, and MDM4 rs4245739 as SNPs in miRNA binding sites highly promising in the biology of human cancer. However, more studies are needed to better characterize the composite spectrum of genetic determinants for future use of markers in risk prediction and clinical management of diseases, heading toward personalized medicine.

Vitamin D3 insufficiency and colorectal cancer

Traditionally the main recognized function of vitamin D has been calcium and phosphate homeostasis. Nevertheless, recent evidences have highlighted the importance of vitamin D3 as a protective agent against various cancers. The association between CRC and vitamin D3 was first suggested in ecologic studies, but further was confirmed by observational studies in humans and experimental studies in both animal models and cellular lines. The protective role of vitamin D3 against cancer has been attributed to its influence of on cell proliferation, differentiation, apoptosis, DNA repair mechanisms, inflammation and immune function. In its active (calcitriol) form (1,25-dihydroxyvitamin D3[1α,25-(OH)2D3]) vitamin D3 and the nuclear vitamin D receptor (VDR) regulate hundreds of genes including those coding for proteins involved in cell differentiation and cell proliferation. The current review addresses some of the key mechanisms that influence the biological actions of vitamin D and its metabolites. The insights derived from these mechanisms may aid in designing new uses for this hormone and its non-hypercalcemic derivatives in the treatment and/or prevention of CRC.

The sum of many small changes: microRNAs are specifically and potentially globally altered by vitamin D3 metabolites

Vitamin D3 deficiency is rampant which may contribute to increased risk of many diseases including cancer, cardiovascular disease and autoimmune disorders. Genomic activity of the active metabolite 1,25-dihydroxyvitamin D (1,25D) mediates most vitamin D3's actions and many gene targets of 1,25D have been characterized. As the importance of non-coding RNAs has emerged, the ability of vitamin D3via 1,25D to regulate microRNAs (miRNAs) has been demonstrated in several cancer cell lines, patient tissue and sera. In vitamin D3 intervention patient trials, significant differences in miRNAs are observed between treatment groups and/or between baseline and followup. In patient sera from population studies, specific miRNA differences associate with serum levels of 25D. The findings thus far indicate that dietary vitamin D3 in patients and 1,25D in vitro not only regulate specific miRNA(s), but may also globally upregulate miRNA levels. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

A walnut-enriched diet reduces the growth of LNCaP human prostate cancer xenografts in nude mice

It was investigated whether a standard mouse diet (AIN-76A) supplemented with walnuts reduced the establishment and growth of LNCaP human prostate cancer cells in nude (nu/nu) mice. The walnut-enriched diet reduced the number of tumors and the growth of the LNCaP xenografts; 3 of 16 (18.7%) of the walnut-fed mice developed tumors; conversely, 14 of 32 mice (44.0%) of the control diet-fed animals developed tumors. Similarly, the xenografts in the walnut-fed animals grew more slowly than those in the control diet mice. The final average tumor size in the walnut-diet animals was roughly one-fourth the average size of the prostate tumors in the mice that ate the control diet.

Role of calcium sensing receptor (CaSR) in tumorigenesis

The extracellular Ca(2+)-sensing receptor (CaSR) is a robust promoter of differentiation in colonic epithelial cells and functions as a tumor suppressor in colon cancer. CaSR mediates its biologic effects through diverse mechanisms. Loss of CaSR expression activates a myriad of stem cell-like molecular features that drive and sustain the malignant and drug-resistant phenotypes of colon cancer. This CaSR-null phenotype, however, is not irreversible and induction of CaSR expression in CaSR-null cells promotes cell death mechanisms and restores drug sensitivity. The CaSR also functions as a tumor suppressor in breast cancer and promotes cellular sensitivity to cytotoxic drugs. BRCA1 and CaSR functions intersect in breast cancer cells, and CaSR activation can rescue breast cancer cells from the deleterious effect of BRCA1 mutations.

Efficacy of EGFR inhibition is modulated by model, sex, genetic background and diet: implications for preclinical cancer prevention and therapy trials

Molecule-targeted therapies are being widely developed and deployed, but they are frequently less effective in clinical trials than predicted based upon preclinical studies. Frequently, only a single model or genetic background is utilized using diets that are not relevant to that consumed by most cancer patients, which may contribute to the lack of predictability of many preclinical therapeutic studies. Inhibition of epidermal growth factor receptor (EGFR) in colorectal cancer was used to investigate potential causes for low predictive values of many preclinical studies. The efficacy of the small molecule EGFR inhibitor AG1478 was evaluated using two mouse models, Apc^Min/+ and azoxymethane (AOM), both sexes on three genetic backgrounds, C57BL/6J (B6) and A/J (A) inbred strains and AB6F1 hybrids, and two diets, standard chow (STD) or Western-style diet (WD). AG1478 has significant anti-tumor activity in the B6-Apc^Min/+ model with STD but only moderately on the WD and in the AOM model on an A background with a WD but not STD. On the F1 hybrid background AG1478 is effective in the Apc^Min/+ model with either STD or WD, but has only moderate efficacy in the AOM model with either diet. Sex differences were also observed. Unexpectedly, the level of liver EGFR phosphorylation inhibition by AG1478 was not positively correlated with inhibition of tumor growth in the AOM model. Model-dependent interactions between genetic background and diet can dramatically impact preclinical results, and indicate that low predictive values of preclinical studies can be attributed to study designs that do not account for the heterogeneous patient population or the diets they consume. Better-designed preclinical studies should lead to more accurate predictions of therapeutic response in the clinic.

Dietary calcium supplementation enhances efficacy but also toxicity of EGFR inhibitor therapy for colon cancer

The inverse correlation between levels of dietary calcium and colorectal cancer (CRC) incidence has been extensively investigated. However, the impact of supplemental calcium on cancer therapy remains unknown. We used four models of CRC, Caco-2 and HCT116 human cancer cell lines and Apc (Min/+) and azoxymethane carcinogen-induced mouse models, to investigate the impact of a western-style diet low in calcium (0.05%) vs. a similar diet but supplemented with calcium (5%) on therapeutic targeting of the epidermal growth factor receptor (EGFR). We found that calcium supplementation combined with pharmacologic blockade of EGFR results in an additive effect on tumor growth inhibition in all models. Unexpectedly, the combined use of dietary calcium supplementation and EGFR inhibitors also resulted in elevated toxicity suggesting that careful consideration be given when combining dietary supplements with prescribed cancer therapies.

Vitamin D and mammographic breast density: a systematic review

Studies suggest a protective relationship between Vitamin D and breast cancer risk. Several studies assessed the association of Vitamin D with mammographic breast density, a known and strong breast cancer risk factor. Understanding the potential role of Vitamin D in the modification of breast density might open new avenues in breast cancer prevention. This systematic review summarizes published studies that investigated the association between Vitamin D and mammographic breast density and offers suggestions for strategies to advance our scientific knowledge.

High fat diet reduces the expression of glutathione peroxidase 3 in mouse prostate

BACKGROUND

High fat diets are known to be a risk factor for prostate cancer. In this study, we investigated the effect of high fat diet on mouse prostate gene expression.

METHODS

C57BL/6J mice were fed either a control or high fat diet for 12 weeks. Microarray analyses were performed on mouse ventral prostate (VP) and dorsolateral prostate (DLP), followed by canonical pathway analysis and regulatory network identification. mRNA changes were confirmed by real time PCR.

RESULTS

Approximately 2,125, and 1,194 genes responded significantly to the high fat diet in VP, DLP, respectively. Pathways and networks related to oxidative stress, glutathione metabolism, NRF-mediated oxidative stress response and NF-kappaB were all differentially regulated by high fat diet. Glutathione peroxidase 3 (GPx3) mRNA levels were decreased by approximately twofold by high fat diet in all three prostate lobes. In human non-transformed prostate cells (PrSC, PrEC, and BPH-1), cholesterol loading decreased GPx3 expression, and increased H2 O2 levels of culture medium. Troglitazone increased GPx3 expression in three normal prostate cells, and decreased H2 O2 levels. In addition, troglitazone attenuated cholesterol-induced H2 O2 increase. Tissue from prostate cancer biopsies had decreased GPx3 mRNA and its level was inversely related to the Gleason score.

CONCLUSIONS

High fat diet alters pathways related to many genes concerned with oxidative stress. GPx3, a gene identified by this analysis, was found to be down-regulated by high fat diet and appears be decreased in human prostate cancers, suggesting that GPx3 may have a possible role in modulating carcinogenesis. Prostate 71:1499-1509, 2011. © 2011 Wiley-Liss, Inc.

Functional SNP in the microRNA-367 binding site in the 3'UTR of the calcium channel ryanodine receptor gene 3 (RYR3) affects breast cancer risk and calcification

We have evaluated and provided evidence that the ryanodine receptor 3 gene (RYR3), which encodes a large protein that forms a calcium channel, is important for the growth, morphology, and migration of breast cancer cells. A putative binding site for microRNA-367 (miR-367) exists in the 3'UTR of RYR3, and a genetic variant, rs1044129 A→G, is present in this binding region. We confirmed that miR-367 regulates the expression of a reporter gene driven by the RYR3 3'UTR and that the regulation was affected by the RYR3 genotype. A thermodynamic model based on base pairing and the secondary structure of the RYR3 mRNA and miR-367 miRNA showed that miR-367 had a higher binding affinity for the A genotype than for the G genotype. The rs1044129 SNP was genotyped in 1,532 breast cancer cases and 1,600 healthy Chinese women. The results showed that compared with the AA genotype, G was a risk genotype for breast cancer development and was also associated with breast cancer calcification and poor survival. Thus, rs1044129 is a unique SNP that resides in a miRNA-gene regulatory loop that affects breast cancer risk, calcification, and survival.

Omics underpins novel clues on VDR chemoprevention target in breast cancer

Breast cancer is the commonest form of female malignancy among women in Western countries. The advent of genomic technologies has enhanced the diagnosis and the biological classification of such pathology. It has been demonstrated that cancer takes many years to be fully established. This long dormancy could represent a potential window for intervening with chemoprevention studies. Cancer chemoprevention is by definition the use of natural, synthetic, or biological chemical agents to reverse, suppress, or delay the genetic or other alterations that culminate in the appearance of the tumor phenotype. An important step for the success of chemoprevention is the identification of molecularly targeted agents to prevent cancer development. Currently, only two chemoprevention agents, raloxifene and tamoxifen, are used in clinical practice to prevent breast cancer. In this review, we will mainly focus on: (1) the application of genomic technologies for the identification and validation of molecular targets for chemoprevention; (2) the role of vitamin D and its cognate receptor VDR (vitamin D receptor) as a model for the molecularly targeted chemoprevention of breast cancer.

Association between vitamin D and calcium intake and breast cancer risk according to menopausal status and receptor status in Japan

Although several studies have investigated the possible association between elevated vitamin D and calcium intake and low breast cancer risk, findings have been inconsistent. We conducted a case-control study to clarify the association between vitamin D and calcium intake and breast cancer risk among pre- and post- menopausal women in Japan. We also investigated whether these effects were modified by tumor receptor status, specifically estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor-2 (HER2) status. We examined 1803 breast cancer patients and 3606 age- and menopausal status-matched noncancer controls. Among cases, 713 were assessed for ER, PR, and HER2 status. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated using conditional or unconditional logistic models adjusted for potential confounders. A significant inverse association was observed between vitamin D and calcium intake and breast cancer risk among all subjects, with top quartile ORs of 0.76 (95% CI, 0.63-0.90; trend P = 0.001) and 0.83 (95% CI, 0.69-0.99; trend P = 0.038), respectively. In analyses stratified by menopausal status, a significant association between risk and vitamin D was observed only among premenopausal women (trend P < 0.001), whereas that between risk and calcium intake was seen only among postmenopausal women (trend P = 0.022). Heterogeneity by menopausal status for these associations was statistically significant. This association was modified by tumor receptor status. These findings suggest that the protective effects of vitamin D and calcium intake against breast cancer risk may differ by menopausal status and receptor status.

Western-style diets induce oxidative stress and dysregulate immune responses in the colon in a mouse model of sporadic colon cancer

A Western-style diet (WD), defined by high-fat, low-calcium, and vitamin D content, is associated with increased risk of human colorectal cancer. Understanding molecular mechanisms altered by the WD is crucial to develop preventive and therapeutic strategies. Effects of a WD on the colonic transcriptome of C57Bl/6J mice, a model for sporadic colon cancer, were studied at endpoints before tumors occur. To assess whether a WD induces inflammatory changes, expression profiles of a broad spectrum of inflammatory proteins were performed and numbers of lamina propria macrophages were determined with semiquantitative morphometry. Transcriptome changes were translated into molecular interaction network maps and pathways. Pathways related to oxidative stress response; lipid, glutathione, and xenobiotic metabolism; and the immune response were perturbed by the WD. Several nuclear factor-erythroid 2-related factor 2- and aryl hydrocarbon receptor-dependent genes, including those coding for enzymes involved in phase 1 and 2 drug metabolism and oxidative stress responses, were induced. Oxidative stress was demonstrated by measurements of endogenous colonic redox-sensitive compound concentrations. Perturbations in immune response-related pathways, expression of inflammatory proteins, and increased numbers of lamina propria macrophages showed that the WD significantly alters the local colonic immune response. Collectively, these data suggest that consumption of a WD interferes with networks of related biological response pathways involving colonic lipid metabolism, oxidative stress, and the immune response. These new findings impact our understanding of links between consumption of WD and colon carcinogenesis, providing additional information for developing preventive means for decreasing colorectal cancer risk.

Meta-analysis of vitamin D, calcium and the prevention of breast cancer

Vitamin D and calcium intake have been suggested to have protective effects against breast cancer; however, the data have been inconclusive. The present meta-analysis examined the overall effects of vitamin D intake, circulating 25(OH)D and 1alpha,25(OH)(2)D levels, and calcium intake on breast cancer risk. Data from 11 studies on vitamin D intake, 7 studies on circulating 25(OH)D levels, 3 studies of circulating 1alpha,25(OH)(2)D levels, and 15 studies on calcium intake and breast cancer risk were included in this analysis. From the meta-analysis, there was a significant inverse relationship between vitamin D intake and breast cancer risk, with an overall relative risk (RR) of high versus low vitamin D intake for breast cancer of 0.91 (95% CI = 0.85-0.97). The highest quantile of circulating 25(OH)D was found to be associated with a 45% (OR = 0.55, 95% CI = 0.38-0.80) decrease in breast cancer when compared with the lowest quantile. No significant association for the circulating 1alpha,25(OH)(2)D level and breast cancer was found (OR = 0.99, 95% CI = 0.68-1.44). For calcium, a 19% (RR = 0.81, 95% CI = 0.72-0.90) decrease in breast cancer risk was found for those with highest quantile of calcium intake compared to the lowest quantile. These results provide strong evidence that vitamin D and calcium have a chemopreventive effect against breast cancer.

Vitamin D related genes, CYP24A1 and CYP27B1, and colon cancer risk

Genetic association studies investigating the role of vitamin D in colon cancer have primarily focused on the vitamin D receptor (VDR), with limited data available for other genes in the vitamin D pathway, including vitamin D activating enzyme 1-alpha hydroxylase (CYP27B1) and vitamin D deactivating enzyme 24-alpha hydroxylase (CYP24A1). We evaluated whether 12 tagging single nucleotide polymorphisms (SNP) in CYP24A1, identified by resequencing the gene in 32 Caucasian samples, and 1 SNP in CYP27B1 were associated with colon cancer risk. In addition, we evaluated whether these two genes modify associations between colon cancer on the one hand and total vitamin D intake and UV-weighted sun exposure on the other, as well as other variants in VDR. Unconditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI) for the association between polymorphisms and haplotypes in CYP27B1 and CYP24A1 in a multicenter population-based case-control study of 1,600 cases and 1,949 controls. The CYP24A1 polymorphism IVS4-66T > G showed a statistically significant association with risk of colon cancer overall, particularly for proximal colon cancer. When stratified by anatomic site, we also found statistically significant associations for three CYP24A1 polymorphisms with risk of distal colon cancer (IVS4 + 1653C > T: OR for CT/TT versus CC, 0.81; 95% CI, 0.68-0.96; IVS9 + 198T > C: OR for CC versus TT, 1.33; 95% CI, 1.03-1.73; and within whites only: +4125bp 3' of STPC > G: OR for GG versus CC, 1.44; 95% CI, 1-2.05). In addition, a possible interaction between CYP27B1 and UV-weighted sun exposure with proximal colon cancer was observed. As this is the first study to evaluate these genes in relation to colon cancer, additional studies are needed to confirm these results.

Vitamin D receptor gene polymorphisms and the risk of colorectal cancer in a Chinese population

OBJECTIVE

The purpose was to investigate single nucleotide polymorphism of the vitamin D receptor gene and its possible relationship with colorectal cancer (CRC) in a Chinese population.

METHODS

The vitamin D receptor (VDR) genotypes were determined by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) using endonuclease BsmI and FokI, and direct sequencing in 400 Chinese people, comprised of 200 CRC patients and 200 controls from the same area in China.

RESULTS

The distribution of alleles (F/f) and genotypes (FF/Ff/ff) of the FokI had no significant difference between CRC patients and normal controls (P > 0.05), while that of the B allele and the BB genotype of the BsmI in CRC patients was significantly lower compared with the control group (0.1625 versus 0.740, P < 0.05, OR = 0.068, 95% CI: 0.048-0.096 and 0.060 versus 0.590, P < 0.05, OR = 0.015, 95% CI: 0.007-0.032).

CONCLUSION

The BB genotype of the VDR BsmI variant was significantly associated with a decreased risk of CRC in a Chinese population, while the VDR FokI polymorphism was not significantly associated with it.

Vitamin D and prevention of colorectal adenoma: a meta-analysis

BACKGROUND

Vitamin D status is associated inversely with risk of colorectal cancer, but the association with adenoma risk is less clear. This meta-analysis examined the overall relationship between circulating (plasma or serum) 25-hydroxyvitamin D [25(OH)D], vitamin D intake (dietary, supplemental, or total), and colorectal adenoma incidence in published studies.

METHODS

A meta-analysis composed of 17 epidemiologic studies [1 cross-sectional, 9 case-control, and 7 cohort or nested case-control studies; 7 on 25(OH)D and 12 on vitamin D intake] published before December 2007 was done to examine the association between circulating 25(OH)D, vitamin D intake, and colorectal adenomas. Summary Peto odds ratios (OR) were computed for overall and stratified analyses.

RESULTS

Circulating 25(OH)D was inversely associated with risk of colorectal adenomas: the OR was 0.70 [95% confidence interval (95% CI), 0.56-0.87] for high versus low circulating 25(OH)D. The highest quintile of vitamin D intake was associated with an 11% marginally decreased risk of colorectal adenomas compared with low vitamin D intake (OR, 0.89; 95% CI, 0.78-1.02). For recurrent adenomas, there was a decreased risk of 12% (95% CI, 0.72-1.07) among individuals with high versus low vitamin D intake. The inverse associations appeared stronger for advanced adenoma [OR, 0.64; 95% CI, 0.45-0.90 for serum 25(OH)D and OR, 0.77; 95% CI, 0.63-0.95 for vitamin D intake], but the number of studies was small.

CONCLUSIONS

Both circulating 25(OH)D and vitamin D intake were inversely associated with colorectal adenoma incidence and recurrent adenomas. These results further support a role of vitamin D in prevention of colorectal adenoma incidence and recurrence.

Long-term dietary calcium intake and breast cancer risk in a prospective cohort of women

BACKGROUND

Calcium may potentially influence the risk of breast cancer because of its role in regulating cell proliferation, differentiation, and apoptosis. However, prospective studies of calcium intake in relation to breast cancer incidence are sparse.

OBJECTIVE

The objective of this study was to prospectively examine and show the association, if any, of dietary calcium intake with risk of breast cancer by estrogen receptor (ER) and progesterone receptor (PR) status of the tumor.

DESIGN

The Swedish Mammography Cohort is a population-based prospective cohort of 61,433 women who were cancer-free at enrollment in 1987-1990. Dietary calcium intake was assessed with a food-frequency questionnaire at baseline and again in 1997. Cox proportional hazards models were used to estimate rate ratios (RRs) and 95% CIs, adjusted for breast cancer risk factors.

RESULTS

During an average of 17.4 y of follow-up, 2,952 incident cases of invasive breast cancer were ascertained. Dietary calcium intake was not associated with risk of overall breast cancer; the multivariate RR for the highest compared with the lowest quintile of calcium intake was 0.97 (95% CI: 0.87, 1.09; P for trend: 0.49). There was a statistically significant inverse trend for ER-negative/PR-negative (ER-/PR-) breast cancer (P for trend: 0.02); the multivariate RR for the comparison of extreme quintiles of calcium intake was 0.66 (95% CI: 0.44, 0.99). Calcium intake was not associated with ER-positive/PR-positive (ER+/PR+) or ER+/PR- tumors.

CONCLUSIONS

Our findings do not support an association between dietary calcium intake and overall breast cancer risk. The inverse relation between calcium intake and ER-/PR- breast cancer requires confirmation in other studies.

Effect of a Western-style diet fortified with increased calcium and vitamin D on mammary gland of C57BL/6 mice

We previously reported hyperproliferation and hyperplasia in C57Bl/6 mouse mammary gland after feeding a Western-style diet (WD); these findings decreased after supplementing WD with increased calcium and vitamin D(3). We now again fortified WD with increased calcium and vitamin D(3) from two sources: (1) a food source, calcium- and vitamin D(3)-enriched yogurt (WD(y) diet) or (2) adding calcium and vitamin D(3) directly to WD (WD(CaD) diet). After 6 months of feeding the number of mammary ducts was higher in mice consuming WD compared to WD(y) (216.0 vs. 202.7, P <.05) and WD(CaD) (216.0 vs. 194.9, P <.001). The percentage of small ducts increased in WD compared to AIN-76A controls (23.3% vs. 17.4%) but was lower in the WD(y) (17.1%) and WD(CaD) (14.8%) groups. WD mice had higher numbers of epithelial cells per duct than WD(y) (33.2 vs. 27.4, P <.001) and WD(CaD) (33.2 vs. 27.8, P <.001) mice, and AIN-76A-fed mice had higher numbers than WD(y) (31.1 vs. 27.4, P <.005) or WD(CaD) (31.1 vs. 27.8, P <.01) mice. Mitotic index was higher in WD than in WD(CaD) mice (0.0020 vs. 0.0009, P <.001). Thus, small mammary gland ductules and mitosis increased after feeding WD and decreased after supplementing the diets with increased calcium and vitamin D(3), administered either in a dairy food (yogurt) or directly as calcium carbonate plus vitamin D(3) in WD, suggesting further study of these nutrients for their possible relationship to breast cancer prevention.

The vitamin D receptor in cancer

Over the last 25 years roles have been established for vitamin D receptor (VDR) in influencing cell proliferation and differentiation. For example, murine knock-out approaches have revealed a role for the VDR in controlling mammary gland growth and function. These actions appear widespread, as the enzymes responsible for 1alpha,25-dihydroxycholecalciferol generation and degradation, and the VDR itself, are all functionally present in a wide range of epithelial and haematopoietic cell types. These findings, combined with epidemiological and functional data, support the concept that local, autocrine and paracrine VDR signalling exerts control over cell-fate decisions in multiple cell types. Furthermore, the recent identification of bile acid lithocholic acid as a VDR ligand underscores the environmental sensing role for the VDR. In vitro and in vivo dissection of VDR signalling in cancers (e.g. breast, prostate and colon) supports a role for targeting the VDR in either chemoprevention or chemotherapy settings. As with other potential therapeutics, it has become clear that cancer cells display de novo and acquired genetic and epigenetic mechanisms of resistance to these actions. Consequently, a range of experimental and clinical options are being developed to bring about more targeted actions, overcome resistance and enhance the efficacy of VDR-centred therapeutics.

Vitamin D and breast cancer risk

In addition to its important role in the maintenance of the skeleton, there is mounting evidence that vitamin D has effects on other body systems, and that adequate supplies of vitamin D are likely to be required for optimal health. Vitamin D is obtained both from dietary sources and from cutaneous synthesis with exposure to sunlight. Some epidemiological studies have indicated that vitamin D deficiency and decreased exposure to solar UVB radiation increase the risk of some cancers, including breast cancer. The active metabolite of vitamin D, 1,25-dihydroxy-vitamin D(3), is synthesized primarily in the kidney, and has been shown in laboratory studies to have potent anti-proliferative effects on breast cancer cells. Normal and neoplastic breast tissues contain the vitamin D receptor, and gene ablation studies have implicated the receptor in normal breast development. Several polymorphisms have been identified in the vitamin D receptor gene, and these have been associated with risk of breast cancer in some studies. Local synthesis of 1,25-dihydroxyvitamin D(3) in breast tissue may contribute to maintenance of normal cell function, which could be impaired in vitamin D deficiency.

Association of vitamin D receptor gene variants, adiposity and colon cancer

Vitamin D receptor (VDR) gene variants have been variably associated with risk of colon cancer in epidemiologic studies. We sought to further clarify the relationship between colon cancer and three single-nucleotide polymorphisms (SNPs) in the VDR gene (Cdx-2, FokI and TaqI) in a population-based case-control study of 250 incident cases and 246 controls. Colon cancer cases were more frequently homozygous for the Cdx-2 A allele (9.2 versus 4.1%, P = 0.06). Cdx-2 AA homozygotes were at increased risk with an unadjusted odds ratio (OR) of 2.47 [95% confidence interval (CI): 1.13-5.37, P = 0.022]; adjustment for age, sex, body mass index (BMI), non-steroidal anti-inflammatory use and family history of colorectal cancer yielded an OR of 2.27 (CI: 0.95-5.41, P = 0.065). Carriers of the FokI TT genotype were also at increased risk with an adjusted OR of 1.87 (CI: 1.03-3.38, P = 0.038). Haplotype analyses showed significant increased colon cancer risk for carriers of the Cdx-2-FokI A-T haplotype and the FokI-TaqI T-G haplotype. The three-SNP Cdx-2-FokI-TaqI (A-T-G) haplotype showed a similar association with an adjusted OR of 3.63 (CI: 1.01-13.07). A strong positive association was observed for the Cdx-2 variant among individuals with low BMI or low waist circumference. Our results suggest that genetic variation at the VDR locus, in particular Cdx-2 and FokI SNPs, may influence colon cancer risk and these associations may be modified by adiposity.

Serum metabolite profiles and target tissue gene expression define the effect of cholecalciferol intake on calcium metabolism in rats and mice

We studied the effect of cholecalciferol (VD3) intake on VD3 status and markers of calcium (Ca) homeostasis in mice and rats. Serum 25 hydroxycholecalciferol (25OH-VD3) concentrations were increased in animals fed diets containing 400-20,000 international units (IU) VD3/kg (37 nmol.L(-1).1000 IU VD3(-1)), but body weight, serum Ca, and duodenal gene expression were not altered. High-VD3 intake decreased serum 1, 25-dihydroxycholecalciferol [1,25(OH)2-VD3] and renal 25 hydroxycholecalciferol-1alphahydroxylase (CYP27B1) mRNA, suggesting that rodents tolerate high-VD3 intake by suppressing the activity of the VD3 endocrine system. Serum 25OH-VD3 declined when animals were fed diets containing 1000 to 25 IU VD3/kg (9-11 wk, inflection at 200 IU/kg, 4-fold steeper slope below this). Neither body weight nor serum Ca were influenced by low-VD3 intake. However, mice fed the 25-IU/kg diet had lower serum 1,25(OH)2-VD3, duodenal calbindin D9k mRNA, bone mineral density, and renal 25 hydroxycholecalciferol-24 hydroxylase mRNA, whereas renal CYP27B1 mRNA was elevated when rodents were fed < 200 IU VD3/kg. These data reveal a stress on VD3 and Ca metabolism at low dietary VD3 intake. Dietary Ca restriction (0.25 vs. 0.5%, 9 wk) increased serum 1,25(OH)2-VD3 and was 30% greater in rats fed a 10,000-IU VD3/kg diet. High-VD3 intake did not prevent Ca restriction-induced bone loss. Our data show that modeling human VD3 status requires lower intake than the current NRC rodent requirement (1000-IU/kg diet). Also, although rodents are very tolerant of high-VD3 intake, it cannot compensate for moderate Ca restriction.

Review article: nutrition, obesity and colorectal cancer

BACKGROUND

The age-adjusted incidence of colorectal cancer is higher in prosperous industrialized countries than elsewhere. Dietary factors may account for 75% of sporadic colorectal cancer in the west, but the mechanisms remain obscure.

AIM

To review evidence for the effects of overweight and obesity, physical activity and specific dietary components on colorectal neoplasia.

METHODS

English language papers cited on MEDLINE, obtained using search terms related to colorectal cancer, physical activity and body mass and specific food components were reviewed.

RESULTS

There is evidence for adverse effects of overweight and obesity and protective effects of high physical activity against colon, but not for rectal cancer. These effects may reflect metabolic stress and chronic low-grade inflammation. There are also modest adverse effects of red and processed meat. There is evidence for protective effects of dietary fibre, but for fruits and vegetables the evidence remains weak and inconclusive. There is some evidence for protective effects of n-3 polyunsaturated fatty acids from fish, some micronutrients and possibly phytochemicals. The effects of many dietary constituents may depend upon genetic polymorphisms affecting a variety of genes.

CONCLUSION

Further research should focus particularly on the effects of insulin-resistance, impaired glucose tolerance and chronic low-grade inflammation on the colonic mucosa.

Prospective study of serum 25(OH)-vitamin D concentration and risk of oesophageal and gastric cancers

We prospectively examined the relation between pretrial serum vitamin D status and risk of oesophageal and gastric cancers among subjects who developed cancer over 5.25 years of follow-up, including 545 oesophageal squamous cell carcinomas (ESCC), 353 gastric cardia adenocarcinomas, 81 gastric noncardia adenocarcinomas, and an age- and sex-stratified random sample of 1105 subjects. The distribution of serum 25(OH)D was calculated using the known sampling weights. For the cohort as a whole, the 25th, 50th, and 75th percentile concentrations of 25(OH)-vitamin D were 19.6, 31.9, and 48.7 nmol l(-1), respectively, and we found that higher serum 25(OH)D concentrations were associated with monotonically increasing risk of ESCC in men, but not in women. Comparing men in the fourth quartile of serum 25(OH)D concentrations to those in the first, we found a hazard ratio (HR) (95% confidence interval (CI)) of 1.77 (1.16-2.70), P trend=0.0033. The same comparison in women had a HR (95% CI) of 1.06 (0.71-1.59), P trend=0.70. We found no associations for gastric cardia or noncardia adenocarcinoma. Among subjects with low vitamin D status, higher serum 25(OH)D concentrations were associated with significantly increased risk of ESCC in men, but not in women. Further refinements of the analysis did not suggest any factors, which could explain this unexpected result.

Modeling cancer patient populations in mice: complex genetic and environmental factors

Genetic differences among individuals contribute to differential susceptibility to cancer and, undoubtedly, to variable efficacy and toxicity of pharmacological-based therapeutics. Many of the specific molecular processes involved in human tumorigenesis have been elucidated and accurately modeled in mice. However, the current models used for drug testing do not accurately predict how new treatments will fare in clinical trials. More sophisticated models that treat cancer as a complex disease present within heterogenous patient populations will provide better predictive power to identify patients that may benefit from specific therapies or that may develop potential drug-induced toxicities.

The vitamin D receptor as a therapeutic target

The vitamin D receptor (VDR) is a member of the large family of nuclear receptor transcription factors and specifically binds the micronutrient-derived hormone 1alpha,25(OH)2D3. A central endocrine role for this receptor in bone health was established at the beginning of the 20th century. Over the last 25 years, additional roles, perhaps through autocrine and paracrine mechanisms, have been established for VDR to regulate cell proliferation and differentiation, and more recently to exert immunomodulatory and antimicrobial functions. These findings, from in vitro and in vivo experiments, have generated considerable interest in targeting the VDR in multiple therapeutic settings. As with many potential therapeutics, it has also become clear that cells and tissues may also display de novo and acquired mechanisms of resistance to these actions. Consequently, a range of experimental and clinical options are being developed to bring about more targeted actions, overcome resistance and enhance efficacy of VDR-centred therapeutics.

Relationship Between Calcium, Lactose, Vitamin D, and Dairy Products and Ovarian Cancer

Few prospective studies of the relationship between intake of dairy foods, calcium, vitamin D, and lactose and ovarian cancer have been conducted, and results have been largely inconsistent. Two recent studies found significant increased risk with frequent dairy consumption and perhaps with high intakes of calcium or lactose. The authors investigated the association between these foods and nutrients and ovarian cancer risk among 31,925 subjects in the Breast Cancer Detection Demonstration Project follow-up cohort. Multivariable (MV) relative risks (RRs) adjusted for age, parity, and other factors were estimated using Cox proportional hazards models. Over an average follow-up of 8.3 yr, 146 incident ovarian cancer cases were confirmed. Higher intakes of total dairy food (comparing four or more servings per day vs. less than one serving per day) were associated with a statistically significant decreased risk of ovarian cancer, although the trend was not significant (MV RR = 0.42; 95% confidence interval (CI) = 0.20-0.89; P for trend = 0.07). Comparing extreme quartiles, we observed a statistically nonsignificant inverse association between high dietary calcium intake and ovarian cancer (RR = 0.67; 95% CI = 0.43, 1.04; P for trend = 0.08). No statistically significant relations were found for consumption of specific dairy foods, lactose, or vitamin D and ovarian cancer risk. The possibility of a decreased risk of ovarian cancer for dietary calcium merits further evaluation.

Vitamin D, Calcium, and Breast Cancer Risk: A Review

Vitamin D and calcium are metabolically interrelated and highly correlated dietary factors. Experimental studies have shown their anticarcinogenic effects due to their participation in regulating cell proliferation, differentiation, and apoptosis in normal and malignant breast cells. Given the emerging interest in their potential roles in the etiology of breast cancer, we review the current epidemiologic literature on dietary and/or supplemental intakes of vitamin D, endogenous circulating levels of vitamin D, and dietary and/or supplemental intakes of calcium in relation to breast cancer risk. To place these studies in context, we also provide a brief review of other supporting epidemiologic evidence. Despite inconsistent results from the epidemiologic studies, several lines of evidence suggest that vitamin D and calcium may be involved in the development of breast cancer. Specifically, (a) there is some epidemiologic evidence for inverse associations between vitamin D and calcium intakes and breast cancer; (b) serum, plasma, and/or blood levels of vitamin D metabolites have been inversely associated with breast cancer risk in some studies; (c) high sunlight exposure, presumably reflecting vitamin D synthesis in the skin, has been associated with a reduced risk of breast cancer; (d) vitamin D and calcium intakes have been inversely related to breast density, an intermediate end point for breast cancer; (e) calcium has been associated with a reduced risk of benign proliferative epithelial disorders of the breast, putative precursors of breast cancer; and (f) certain polymorphisms of the vitamin D receptor might modify breast cancer susceptibility. To further confirm the potential protective effects of calcium and vitamin D on breast cancer, well-designed cohort studies and clinical trials are warranted.

Prospective study of predictors of vitamin D status and cancer incidence and mortality in men

BACKGROUND

Vitamin D has potent anticancer properties, especially against digestive-system cancers. Many human studies have used geographic residence as a marker of solar ultraviolet B and hence vitamin D exposure. Here, we considered multiple determinants of vitamin D exposure (dietary and supplementary vitamin D, skin pigmentation, adiposity, geographic residence, and leisure-time physical activity-to estimate sunlight exposure) in relation to cancer risk in the Health Professionals Follow-Up Study.

METHODS

Among 1095 men of this cohort, we quantified the relation of these six determinants to plasma 25-hydroxy-vitamin D [25(OH)D] level by use of a multiple linear regression model. We used results from the model to compute a predicted 25(OH)D level for each of 47,800 men in the cohort based on these characteristics. We then prospectively examined this variable in relation to cancer risk with multivariable Cox proportional hazards models.

RESULTS

From 1986 through January 31, 2000, we documented 4286 incident cancers (excluding organ-confined prostate cancer and nonmelanoma skin cancer) and 2025 deaths from cancer. From multivariable models, an increment of 25 nmol/L in predicted 25(OH)D level was associated with a 17% reduction in total cancer incidence (multivariable relative risk [RR] = 0.83, 95% confidence interval [CI] = 0.74 to 0.92), a 29% reduction in total cancer mortality (RR = 0.71, 95% CI = 0.60 to 0.83), and a 45% reduction in digestive-system cancer mortality (RR = 0.55, 95% CI = 0.41 to 0.74). The absolute annual rate of total cancer was 758 per 100,000 men in the bottom decile of predicted 25(OH)D and 674 per 100,000 men for the top decile; these respective rates were 326 per 100,000 and 277 per 100,000 for total cancer mortality and 128 per 100,000 and 78 per 100,000 for digestive-system cancer mortality. Results were similar when we controlled further for body mass index or physical activity level.

CONCLUSIONS

Low levels of vitamin D may be associated with increased cancer incidence and mortality in men, particularly for digestive-system cancers. The vitamin D supplementation necessary to achieve a 25(OH)D increment of 25 nmol/L may be at least 1500 IU/day.