Vitamin D receptor polymorphisms and breast cancer risk in a large population-based case-control study of Caucasian and African-American women

Vitamin D receptor polymorphisms and associated miRNAs in the development of breast cancer in African American women

Breast cancer (BCa) is a prevalent form of cancer in women, exhibiting varying rates and distribution across different ethnic groups. Among these groups, African American (AA) women have the highest incidence of BCa and the lowest levels of Vitamin D (VD). Numerous studies have explored the connection between variations in the VDR gene and BCa risk, particularly in different populations, but research on the AA population remains limited. Epigenetic modifications, including specific microRNAs (miRNAs), can influence gene expression without altering the genetic code and have been implicated in cancer initiation and progression. Our hypothesis suggests that VDR gene variations may increase BCa risk in AA women and that changes in miRNA expression profiles could contribute to BCa development. Using data from the 1000 Genome Project, we identified five VDR gene variants with significant frequency differences between AA and European-American (EA) populations. We genotyped 404 African American BCa cases and controls for five variants using TaqMan® assays. SNPstats assessed their association with BCa risk. The rs1544410 variant's recessive model (A/A) showed a decreased BCa risk in AA (odds ratio 0.33, 95% CI: 0.15-0.73, p-value 0.0041). Conversely, the rs2853563 variant's recessive model (A/A) was linked to an increased BCa risk (odds ratio 4.04, 95% CI: 1.49-10.95, p-value 0.0022). We investigated miRNA expression influenced by VD in HCC1806 Triple-Negative Breast Cancer (TNBC) cell lines with the A/A allele for rs2853563. nCounter® Nanostring technology assessed miRNA profiles after calcitriol treatment. Our results indicated that calcitriol treatment led to reduced expression of six miRNAs, four of which are associated with tumor suppression in the presence of the AA genotype in TNBC cell lines. These findings suggest that specific VDR genotypes could have a potential effect on the miRNAs expression which could potentially serve as markers for cell proliferation in TNBC.

Potential interplay between tumor size and vitamin D receptor (VDR) polymorphisms in breast cancer prognosis: a prospective cohort study

PURPOSE

Vitamin D has some anticancer properties that may decrease breast cancer risk and improve prognosis. The aim was to investigate associations between four previously studied VDR SNPs (Taq1, Tru91, Bsm1, and Fok1) and prognosis in different groups of breast cancer patients.

METHODS

VDR genotyping of 1,017 breast cancer patients included 2002-2012 in Lund, Sweden, was performed using Oncoarray. Follow-up was until June 30, 2019. Clinical data and patient information were collected from medical records and questionnaires. Cox regression was used for survival analyses.

RESULTS

Genotype frequencies were as follows: Fok1 (AA 15.7%, AG 49.1%, GG 35.1%), Bsm1 (CC 37.2%, CT 46.1%, TT 16.7%), Tru91 (CC 77.8%, CT 20.7%, TT 1.5%), and Taq1 (AA 37.2%, AG 46.2%, GG 16.6%). During follow-up there were 195 breast cancer events. The homozygous variants of Taq1 and Bsm1 were associated with reduced risk of breast cancer events (adjusted HR = 0.59, 95% CI 0.38-0.92 for Taq1 and adjusted HR = 0.61, 95% CI 0.40-0.94 for Bsm1). The G allele of the Fok1 was associated with increased risk of breast cancer events in small tumors (pT1, adjusted HR = 1.83, 95% CI 1.04-3.23) but not in large tumors (pT2/3/4, adjusted HR = 0.80, 95% CI 0.41-1.59) with a borderline interaction (Pinteraction = 0.058). No interactions between VDR genotypes and adjuvant treatments regarding breast cancer prognosis were detected.

CONCLUSION

VDR genotypes were associated with breast cancer prognosis and the association might be modified by tumor size. Further research is needed to confirm the findings and elucidate their potential clinical implications.

Vitamin D, Th17 Lymphocytes, and Breast Cancer

Simple Summary

The effect of vitamin D₃ on the development of breast cancer (favorable, ineffective, or even unfavorable) depends on many factors, such as age, menopausal status, or obesity. The immunomodulatory effect of vitamin D may be unfavorable in case of breast cancer progression. The effect of vitamin D on Th17 cells may depend on disease type and patients’ age. Our goal was to summarize the data available and to find indications of vitamin D treatment failure or success. Therefore, in this review, we present data describing the effects of vitamin D₃ on Th17 cells, mainly in breast cancer.

Abstract

Vitamin D₃, which is well known to maintain calcium homeostasis, plays an important role in various cellular processes. It regulates the proliferation and differentiation of several normal cells, including immune and neoplastic cells, influences the cell cycle, and stimulates cell maturation and apoptosis through a mechanism dependent on the vitamin D receptor. The involvement of vitamin D₃ in breast cancer development has been observed in numerous clinical studies. However, not all studies support the protective effect of vitamin D₃ against the development of this condition. Furthermore, animal studies have revealed that calcitriol or its analogs may stimulate tumor growth or metastasis in some breast cancer models. It has been postulated that the effect of vitamin D₃ on T helper (Th) 17 lymphocytes is one of the mechanisms promoting metastasis in these murine models. Herein we present a literature review on the existing data according to the interplay between vitamin D, Th17 cell and breast cancer. We also discuss the effects of this vitamin on Th17 lymphocytes in various disease entities known to date, due to the scarcity of scientific data on Th17 lymphocytes and breast cancer. The presented data indicate that the effect of vitamin D₃ on breast cancer development depends on many factors, such as age, menopausal status, or obesity. According to that, more extensive clinical trials and studies are needed to assess the importance of vitamin D in breast cancer, especially when no correlations seem to be obvious.

Assessment the effect of vitamin D supplementation on plasma vitamin D levels, inflammation, and oxidative stress biomarkers based on vitamin D receptor genetic variation in breast cancer survivors: a protocol for clinical trial

BACKGROUND

Both human genes and environmental exposures, due to complex interplay, play important role in the cancer etiology. Vitamin D is associated with a reduced risk of incidence and mortality of several human cancers. This study will aim to investigate the possible effects of individual polymorphisms in vitamin D receptor (VDR) as well as effects of VDR haplotypes on response to vitamin D supplementation in breast cancer survivors.

METHODS

This is an interventional study in which the effects of vitamin D supplementation on plasma vitamin D levels, inflammatory and antioxidant biomarkers and factors associated with cell proliferation, differentiation, damage, and apoptosis will be investigated stratified by variations in VDR genotype. The present study will be conducted on breast cancer survivors referred to the Shohadaye Tajrish hospital and its associated clinics. One hundred ninety-eight breast cancer survivors will receive 4000 IU of vitamin D3 daily for 12 weeks. VDR Fok1, ApaI, TaqI, BsmI, and Cdx-2 genotype will be determined at the end of the study and responses to vitamin D supplements (inflammatory, antioxidant, cell proliferation, differentiation, damage, and apoptosis biomarkers) will be compared between the three subgroups of each VDR polymorphism as well as different VDR haplotype categories.

DISCUSSION

Genetic variation is a fundamental factor influencing individuals' divergent responses to diet, nutritional status, metabolic response, and diet-related health disorders. Furthermore, studies of gene and environment interactions will provide a precise and accurate assessments of individuals' dietary requirements by considering both the genetic and environmental aspects simultaneously. The results of the current study, to some extent, will highlight the discrepancies existing in the findings of different studies regarding vitamin D, VDR, and cancer by considering both the genetic and environmental aspects simultaneously. If responses to vitamin D supplementation could be modified by VDR SNPs, determining the distribution of VDR polymorphisms in both breast cancer survivors and healthy populations will provide a new insight into the vitamin D requirements of individuals to prevent cancer and its related mortality based on their genotypes. Trial registration This trial has been registered on Iranian Registry of Clinical Trials (IRCT) under the identification code: IRCT2017091736244N1, registration date: 2017-11-10, http://www.irct.ir/trial/27153.

Vitamin D Receptor (VDR) Allelic Variants Correlating with Response to Vitamin D3 Supplementation in Breast Cancer Survivors

We investigated how vitamin D receptor (VDR) allelic variants affect breast cancer survivors' responses to vitamin D3 supplementation to increase circulating 25-hydroxy vitamin D (25(OH)D) levels. Two hundred and fourteen patients who were diagnosed with breast cancer at least 6 mo, prior to the study and had completed all treatment regimens were assigned to consume 4000 IU of vitamin D3 daily for 12 weeks. Linear and multinomial logistic regression analyses were used to analyze the association of VDR single nucleotide polymorphism (SNPs) with changes in circulating 25(OH)D. The TaqI and BsmI VDR sequence variants modified the effect of vitamin D3 treatment on the plasma 25(OH)D changes (P value = 0.008 for TaqI and P value = 0.0005 for BsmI). Patients with the bb [Q4 vs. Q1 odds ratio(OR) 8.04, 95% confidence interval (CI) 1.55-41.57] and tt [Q4 vs. Q1 OR 4.64 95%CI 1.02-21.02] genotype of BsmI and TaqI had larger increases in plasma 25(OH)D levels compared to those with BB and TT genotype respectively after adjustment for potential confounders. Haplotype analyses suggested the existence of specific combination of alleles that might be associated with circulating 25(OH)D changes. VDR allelic variants modulate vitamin D3 supplementation to increase plasma 25(OH) levels in breast cancer survivors.

Prevalence of vitamin D deficiency in exclusively breastfed infants at a tertiary healthcare facility in Nairobi, Kenya

OBJECTIVE

To determine the prevalence of vitamin D deficiency (VDD) in exclusively breastfed infants at the Aga Khan University Hospital Nairobi, Kenya (AKUHN). The relationships between 25-hydroxyvitamin D; 25OHD, parathyroid hormone (PTH), maternal vitamin D supplementation, and sunlight exposure were also determined.

METHODS

Blood from 98 infants was assayed for 25OHD, calcium, phosphate, and PTH. Socio-demographic and clinical characteristics were analyzed using descriptive statistics and inferential analysis (p < 0.05).

RESULTS

The prevalence of VDD (25OHD <12 ng/mL), vitamin D insufficiency (VDI, 25OHD 12-20 ng/mL) and vitamin D sufficiency (VDS, 25OHD >20 ng/mL) was 11.2% (95% CI 8.0%-14.4%), 12.2% (95% CI 8.9%-15.5%), and 76.5% (95% CI 72.3%-80.8%) respectively. There was no difference in the mean age, head circumference, length, or weight of infants in VDD, VDI, and VDS groups. PTH was elevated when 25OHD was <12 ng/mL and normal when 25OHD was between 12-20 ng/mL. 25OHD and PTH were normal in infants whose mothers received vitamin D supplements. Infants who received <30 minutes/day of exposure to sunlight were 5 times more likely to have VDI than infants who received ≥30 minutes/day (p = 0.042).

CONCLUSION

The prevalence of VDD in exclusively breastfed infants at AKUHN is low. The current national policy that recommends exclusive breastfeeding of infants in the first 6 months of life appears to be effective in staving off vitamin D deficiency but those infants with < 30 minutes sunlight exposure may benefit from low dose supplemental vitamin D during times of low sunlight exposure.

Vitamin D Receptor Polymorphisms and Cancer

Increasing scientific evidence supports the link between vitamin D and cancer risk. The active metabolite 1,25(OH)2D exerts its activity by binding to the vitamin D receptor (VDR), an intracellular receptor that mediates transcriptional activation and repression of target genes. The binding of 1,25(OH)2D to VDR is able to regulate hundreds of different genes. VDR is active in virtually all tissues including the colon, breast, lung, ovary, bone, kidney, parathyroid gland, pancreatic b-cells, monocytes, T lymphocytes, melanocytes, keratinocytes, and also cancer cells.The relevance of VDR gene restriction fragment length polymorphisms for various types of cancer has been investigated by a great number of studies.We have carried out a systematic review of the literature to analyze the relevance of more VDR polymorphisms (Fok1, Bsm1, Taq1, Apa1, and Cdx2) for individual malignancies considering ethnicity as a key factor for heterogeneity.Up to December 2018, we identified 176 independent studies with data to assess the risk of breast, prostate, colorectal, skin (melanoma and non-melanoma skin cancer), lung, ovarian, kidney, bladder, gallbladder, esophageal, thyroid, head and neck, liver and pancreatic cancer, oral squamous cell carcinoma, non-Hodgkin lymphoma, multiple myeloma and sarcoma.Significant associations with VDR polymorphisms have been reported for prostate (Fok1, Bsm1, Taq1, Apa1, Cdx2), breast (Fok1, Bsm1, Taq1, Apa1, CdX2), colorectal (Fok1, Bsm1, Taq1, Apa1), and skin cancer (Fok1, Bsm1, Taq1). Very few studies reported risk estimates for the other cancer sites.Conflicting data have been reported for most malignancies, and at present, it is still not possible to make any definitive statements about the importance of the VDR genotype for cancer risk. It seems probable that other factors such as ethnicity, phenotype, 25(OH)D plasma levels, and UV radiation exposure play a role as confounding factors and introduce heterogeneity.To conclude, there is some indication that VDR polymorphisms may modulate the risk of some cancer sites and in future studies VDR genetic variation should be integrated also with assessment of vitamin D status and stratified by ethnicity.

Do genetic polymorphisms of the vitamin D receptor contribute to breast/ovarian cancer? A systematic review and network meta-analysis

BACKGROUND

To identify the most suitable genetic model for detecting the risk of breast cancer (BC)/ovarian cancer (OC) in specific populations.

METHODS

Databases were searched for related studies published up to October 2017. First, VDR genetic polymorphisms were compared in patients with and without cancer. Second, a network meta-analysis was used to reveal the relation between VDR genetic polymorphisms with disease outcomes. Subgroup analyses and a meta-regression were performed according to cancer types, ethnicity and genotypic method. The study is registered in PROSPERO with an ID: CRD42017075505.

RESULTS

Forty-five studies were eligible, which included 65,754 patients and 55 clinical analyses. Of genetic models, results suggested that the recessive model with the CDX2 polymorphism predicted the risk of BC in all cases. The recessive polymorphism model with the rs2228570 (FokI) polymorphism seemed to the best predictor of BC in Caucasian patients, whereas the homozygote model with the CDX2 polymorphism appeared to best predict BC in African-American patients. The homozygote model with the rs2228570 (FokI) polymorphism model appeared to detect the risk of OC in all cases, whereas the heterozygote model with the rs1544410 (BsmI) polymorphism seemed to detect the risk of OC in Caucasian patients.

CONCLUSIONS

By detecting the risk of BC, the recessive model with the rs2228570 (FokI) polymorphism is likely the best genetic model in Caucasian patients, and the homozygote model with the CDX2 polymorphism appears to be best genetic model in African-American patients. Moreover, for detecting clinical risk of OC, heterozygote models with the rs1544410 (BsmI) polymorphism is likely the best genetic model for detecting the risk of OC in Caucasian patients.

Association between Vitamin D receptor (Cdx2, Fok1, Bsm1, Apa1, Bgl1, Taq1, and Poly (A)) gene polymorphism and breast cancer: A systematic review and meta-analysis

The purpose of this systemic review and meta-analysis was to examine the relationship between VDR gene polymorphisms and breast cancer. Literature was searched through PubMed database, Google scholar, and the web of knowledge from December 2015 to January 2017 and consists of 34 studies (26,372 cases and 32,883 controls). All statistical measures were done using STATA version 11.2. The heterogeneity among studies was tested using I² statistics. Mantel-Haenszel method and DerSimonian-Laird method were used to combine data from studies using both random-effect model and fixed-effect model, respectively. Potential publication bias was evaluated by Egger's test. Sensitivity analysis was also performed to evaluate the quality and consistency in results. The results of this meta-analysis revealed that VDR gene polymorphisms (Bsm1 bb vs BB; SOR = 1.18, 95% CI = 1.054-1.322, Apa1 aa vs AA; SOR = 1.18, 95% CI = 0.87-1.59, Poly (A) LL vs SS; SOR = 1.41, 95% CI = 1.06-1.88, Fok1 ff + Ff vs FF; SOR = 1.25, 95% CI = 0.896-1.759, Apa1 aa+Aa vs AA; SOR = 1.13, 95% CI = 0.95-1.35, Poly (A) LL + LS vs SS; SOR = 1.19, 95% CI = 1.00-1.43, Poly (A) L vs S; SOR = 1.18, 95% CI = 1.03-1.35) are associated with the breast cancer. Cdx2, Bgl1, and Taq1 do not show association with breast cancer. Thus, the finding of this meta-analysis concluded that VDR Bsm1, Apa1, Fok1, and Poly (A) gene polymorphisms may be susceptible for breast cancer development.

Association of vitamin D receptor gene polymorphisms with breast cancer risk in an Egyptian population

This study aimed to explore whether genetic polymorphisms in vitamin D receptor are correlated to the breast cancer prevalence in an Egyptian population. Polymerase chain reaction-restriction fragment polymorphism was used to genotype three frequently analyzed vitamin D receptor gene single-nucleotide polymorphisms (rs1544410, rs7975232, and rs731236) and were identified by sequencing analysis. This is the first study that recorded a new single-nucleotide polymorphism in ApaI genotype within an Egyptian population and was registered with the accession number KY859868. The authors found that TC in rs731236, and TG in KY859868 single-nucleotide polymorphism showed significant distribution differences with an increased risk of breast cancer ( p < 0.05, odds ratio = 3.71, 95% confidence interval: 1.04-13.28 and p < 0.001, odds ratio = 7.05, 95% confidence interval: 2.02-24, respectively) compared with the wild-type TT genotype carriers in both single-nucleotide polymorphisms. In addition, the distribution frequencies of haplotypes ACT, GTT, and ATT in the patients group were significant, where ATT haplotype was associated with the highest breast cancer risk among all other haplotypes in the patients group ( p = 0.0023, odds ratio = 1.72, 95% confidence interval: 1.24-2.437). In conclusion, vitamin D receptors ApaI and TaqI confer high breast cancer susceptibility, particularly in Egyptians females carrying haplotype ATT. However, further studies focusing on the vitamin D receptor variants and haplotypes effects on vitamin D and vitamin D receptor concentrations, activities, and functionalities are needed.

Genetic variation in the vitamin D related pathway and breast cancer risk in women of African ancestry in the root consortium

The vitamin D related pathway has been evaluated in carcinogenesis but its genetic contribution remains poorly understood. We examined single-nucleotide polymorphisms (SNPs) in the vitamin D related pathway genes using data from a genome-wide association study (GWAS) of breast cancer in the African Diaspora that included 3,686 participants (1,657 cases). Pathway- and gene-level analyses were conducted using the adaptive rank truncated product test. Odds ratios (OR) and 95% confidence intervals (CI) were estimated at SNP-level. After stringent Bonferroni corrections, we observed no significant association between variants in the vitamin D pathway and breast cancer risk at the pathway-, gene-, or SNP-level. In addition, no association was found for either the reported signals from GWASs of vitamin D related traits, or the SNPs within vitamin D receptor (VDR) binding regions. Furthermore, a decrease in genetically predicted 25(OH)D levels by Mendelian randomization was not associated with breast cancer (p = 0.23). However, an association for breast cancer with the pigment synthesis/metabolism pathway almost approached significance (pathway-level p = 0.08), driven primarily by a nonsense SNP rs41302073 in TYRP1, with an OR of 1.54 (95% CI = 1.24-1.91, p_adj  = 0.007). In conclusion, we found no evidence to support an association between vitamin D status and breast cancer risk in women of African ancestry, suggesting that vitamin D is unlikely to have significant effect on breast carcinogenesis. Interestingly, TYRP1 might be related to breast cancer through a non-vitamin D relevant mechanism but further studies are needed.

Vitamin D Receptor Gene Polymorphism: Association with Susceptibility to Early-Onset Breast Cancer in Iranian, BRCA1/2-Mutation Carrier and non-carrier Patients

Mounting evidences support that vitamin D insufficiency or deficiency is a risk factor of breast cancer. Vitamin D receptor (VDR) is expressed in more than 36 cell types in different organs as in cancerous cells. Numerous allelic variants of VDR gene have been identified in human populations. Association of FokI (rs2228570) and BsmI (rs1544410) single nucleotide polymorphisms (SNPs) in VDR gene with the risk of breast cancer have been investigated in several studies, however, the published data are still inconsistent. Here, we investigated BsmI and FokI polymorphisms in Iranian young (≤ 35 years old) breast cancer patient with known BRCA1/2 germline mutations. VDR gene polymorphisms were detected by restriction fragment length polymorphism (RFLP) analysis in a cohort of 203 breast cancer patients and 214 controls from Iran. There was a significant association between the bb and Bb genotypes of the BsmI and the increased risk of breast cancer (OR 1.74, CI 1.06-2.87 and OR 2.08, CI 1.31-3.29, respectively). This association was maintained in the subgroup of BRCA1/2 mutation non carriers (OR 1.90, CI 1.15-3.20 and OR 1.75, CI 1.07-2.87 for bb and Bb genotypes respectively) and in the subgroup of BRCA1/2 mutation non-carriers with a family history of breast and/or ovarian cancer (OR 1.81, CI 1.08-3.05 and OR 1.65, CI 1.00-2.70 for bb and Bb genotypes respectively). None of the FokI homozygous or heterozygous genotypes were associated with the risk of breast cancer. In summary, the BsmI polymorphism of VDR gene may be associated with the risk of breast cancer in Iranian women.

Phytotherapy and Nutritional Supplements on Breast Cancer

Breast cancer is the most frequent type of nonskin malignancy among women worldwide. In general, conventional cancer treatment options (i.e., surgery, radiotherapy, chemotherapy, biological therapy, and hormone therapy) are not completely effective. Recurrence and other pathologic situations are still an issue in breast cancer patients due to side effects, toxicity of drugs in normal cells, and aggressive behaviour of the tumours. From this point of view, breast cancer therapy and adjuvant methods represent a promising and challenging field for researchers. In the last few years, the use of some types of complementary medicines by women with a history of breast cancer has significantly increased such as phytotherapeutic products and nutritional supplements. Despite this, the use of such approaches in oncologic processes may be problematic and patient's health risks can arise such as interference with the efficacy of standard cancer treatment. The present review gives an overview of the most usual phytotherapeutic products and nutritional supplements with application in breast cancer patients as adjuvant approach. Regardless of the contradictory results of scientific evidence, we demonstrated the need to perform additional investigation, mainly well-designed clinical trials in order to establish correlations and allow for further validated outcomes concerning the efficacy, safety, and clinical evidence-based recommendation of these products.

Genetic Variation in CYP2R1 and GC Genes Associated With Vitamin D Deficiency Status

This cross-sectional study enrolled 180 patients at a private family practice in Virginia. Total serum vitamin D concentrations were obtained weekly from January 30, 2013, through March 30, 2013, in consecutive patients regularly scheduled for laboratory work at the practice. Patients were categorized into 2 groups and analyzed for variant alleles in vitamin D receptor ( VDR; rs2228570), cytochrome P450 2R1 ( CYP2R1; rs10741657), 7-dehydrocholesterol reductase ( DHCR7; rs12785878), and group-specific component ( GC; rs2282679) to determine whether variants of those alleles influenced total serum 25(OH)D concentrations. One-hundred and eighty patients were enrolled, with 40 (22%) being sufficient, 25-hydroxy vitamin D level 25(OH)D ≥ 30 ng/mL, and 140 (78%) being insufficient, 25(OH)D < 30 ng/mL. Of the 4 genes, 2 genes, CYP2R1 (rs10741657) and GC (rs2282679), demonstrated a significant association related to vitamin D status. Subjects with 1 or more variant alleles at rs10741657 were almost 3.7 (odds ratio [OR] 3.67; 95% confidence interval [CI]: 1.35-9.99) times more likely be insufficient in vitamin D and subjects with 1 or more variant alleles at rs2282679 were about half (OR 0.42; 95% CI: 0.18-0.93) as likely to be insufficient in vitamin D. Allelic variations in CYP2R1 (rs10741657) and GC (rs2282679) affect vitamin D levels, but variant alleles on VDR (rs2228570) and DHCR7 (rs12785878) were not correlated with vitamin D deficiency, 25(OH)D < 30 ng/mL.

Association between the BsmI Polymorphism in the Vitamin D Receptor Gene and Breast Cancer Risk: Results from a Pakistani Case-Control Study

BACKGROUND

Vitamin D is postulated to decrease the risk of breast cancer by inhibiting cell proliferation via the vitamin D receptor (VDR). Two common single nucleotide polymorphisms (SNPs) in the VDR gene, rs1544410 (BsmI) and rs2228570 (FokI), are inconsistently associated with breast cancer risk in Caucasian populations, while data for Asians are scarce. Here, we investigated the possible contribution of these SNPs to breast cancer risk in Pakistani breast cancer patients and in controls participating in a hospital-based breast cancer case-control study (PAK-BCCC).

METHODS

Genotyping of the BsmI and FokI SNPs was performed by PCR-based restriction fragment length polymorphism (RFLP) analysis of 463 genetically enriched female breast cancer cases with known BRCA1/2 status and in 1,012 controls from Pakistan. The association between SNP genotypes and breast cancer risk was investigated by logistic regression adjusted for potential breast cancer risk factors and stratified by BRCA1/2 status and family history. Odds ratios (ORs) and 95% confidence intervals (CIs) were reported.

RESULTS

The b allele of the BsmI was associated with an increased breast cancer risk (per b allele OR 1.28, 95% CI 1.09-1.49, P = 0.003). Subgroup analysis revealed that this effect was restricted to BRCA1/2 non-carriers (per b allele OR 1.33, 95% CI 1.11-1.59, P = 0.002) and was stronger in those who reported a positive family history of breast and/or ovarian cancer (per b allele OR 1.64, 95% CI 1.20-2.22, P = 0.002). No association with breast cancer risk was detected for the FokI SNP.

CONCLUSIONS

The BsmI polymorphism in the VDR gene may be associated with an increased breast cancer risk in Pakistani women negative for BRCA1/2 germline mutations.

Integrated network analysis and logistic regression modeling identify stage-specific genes in Oral Squamous Cell Carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is associated with substantial mortality and morbidity but, OSCC can be difficult to detect at its earliest stage due to its molecular complexity and clinical behavior. Therefore, identification of key gene signatures at an early stage will be highly helpful.

METHODS

The aim of this study was to identify key genes associated with progression of OSCC stages. Gene expression profiles were classified into cancer stage-related modules, i.e., groups of genes that are significantly related to a clinical stage. For prioritizing the candidate genes, analysis was further restricted to genes with high connectivity and a significant association with a stage. To assess predictive power of these genes, a classification model was also developed and tested by 5-fold cross validation and on an independent dataset.

RESULTS

The identified genes were enriched for significant processes and functional pathways, and various genes were found to be directly implicated in OSCC. Forward and stepwise, multivariate logistic regression analyses identified 13 key genes whose expression discriminated early- and late-stage OSCC with predictive accuracy (area under curve; AUC) of ~0.81 in a 5-fold cross-validation strategy.

CONCLUSIONS

The proposed network-driven integrative analytical approach can identify multiple genes significantly related to an OSCC stage; the classification model that is developed with these genes may help to distinguish cancer stages. The proposed genes and model hold promise for monitoring of OSCC stage progression, and our findings may facilitate cancer detection at an earlier stage, resulting in improved treatment outcomes.

Vitamin D Receptor Poly(A) Microsatellite Polymorphism and 25-Hydroxyvitamin D Serum Levels: Association with Susceptibility to Breast Cancer

PURPOSE

According to previous studies, vitamin D exhibits protective effects against breast cancer via the vitamin D receptor (VDR). There is growing evidence that breast cancer incidence is associated with various polymorphisms of the VDR gene. This study investigates the association of VDR poly(A) microsatellite variants with 25-hydroxyvitamin D (25(OH)D) serum levels and breast cancer risk.

METHODS

Polymorphism analysis was performed on a total of 261 blood samples, which were collected from 134 women with breast cancer and 127 controls. Single strand conformation polymorphism was assessed by polymerase chain reaction in combination with sequencing to detect poly(A) lengths for each sample. The vitamin D levels of samples were determined by electrochemiluminescence.

RESULTS

The poly(A) variant L allele frequency was significantly higher in cancer patients than in controls (odds ratio [OR], 1.73; 95% confidence interval [CI], 1.16-2.57; p=0.006). Thus, carriers of the L allele (LS and LL genotypes) have a higher risk for breast cancer (OR, 1.86; 95% CI, 1.13-3.05; p=0.013). A larger increase in the risk for breast cancer was found in individuals with the L carrier genotype and lowered 25(OH)D levels.

CONCLUSION

The results primarily suggest that VDR gene polymorphism in the poly(A) microsatellite is associated with 25(OH)D levels and that it can affect the breast cancer risk in the female population from northern Iran.

Vitamin D receptor gene polymorphisms and breast cancer risk among postmenopausal Egyptian women

Many studies reported that vitamin D can protect against various types of cancers. The mechanism of vitamin D action is mediated by the vitamin D receptor (VDR). VDR may have anti-stress function because it has been identified as p53 direct target gene. This research was designed to investigate the role of VDR polymorphisms BsmI (rs 1544410), ApaI (rs 7975232), TaqI (rs 731236), and FokI (rs 10735810) in pathogenesis of breast cancer using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. The study included 130 postmenopausal breast cancer cases aged 49 to 65 years and 100 controls aged 50 to 72 years. A significantly increased risk of breast cancer among carriers of BsmI bb genotype was observed (OR = 2.5 (1.1-5.6), P = 0.025). Also, a significantly increased risk of breast cancer was detected among women carrying ApaI aa genotype (OR = 2.2 (1.02-4.5), P = 0.04), while no significant associations were observed between breast cancer risk and genotypes and allele frequencies of FokI and TaqI polymorphisms (P > 0.05). Our study showed that VDR gene polymorphisms (BsmI and ApaI) may contribute to breast cancer risk among postmenopausal women.

Vitamin D receptor Cdx-2 polymorphism and premenopausal breast cancer risk in southern Pakistani patients

Background

Vitamin D3 is a secoster oid that exerts its effect by binding to its nuclear receptor called vitamin D receptor (VDR), inducing apoptosis and thereby inhibiting cell proliferation in cancer cells. The VDR receptor, located in the nucleus, is known to regulate the functions of over 200 genes. Various allelic forms of hVDR have been discovered that increase susceptibility to various cancers. The VDR-Cdx2 polymorphism, located in the promoter region of exon 1e in the VDR gene, influences the functional activity of the receptor, since the hVDR lacks consensus TATA and CAAT boxes. The current investigation examines the association between VDR-Cdx2 polymorphism and breast cancer in premenopausal females from Southern Pakistan.

Methods

We conducted a case control study on 264 subjects (103 cases and 161 controls) who were recruited from a tertiary hospital located in Karachi, Pakistan. Genomic DNA was extracted from peripheral blood using a commercial kit method, and the VDR-Cdx2 polymorphism was genotyped using tetraprimer amplification refractory mutation system polymerase chain reaction (T-ARMS-PCR) method. Pearson chi square test was used to assess the association between VDR-Cdx2 genotype and breast cancer while genotype distribution in controls was evaluated by Hardy-Weinberg equilibrium (HWE). Breast cancer risk was calculated using odds ratios and 95% confidence intervals.

Results

The genotype distribution in the control group was in HWE (p > 0.05) for the VDR-Cdx2 polymorphism. A non-significant association was observed between VDR cdx2 polymorphism and breast cancer, however the GG genotype was at risk (OR = 1.832, 95% CI = 0.695–4.828) of developing breast cancer.

Conclusion

The GG genotype of Cdx2-VDR gene polymorphism may increase the risk of developing breast cancer in young female patients in South Pakistan. Further investigations examining additional single nucleotide polymorphisms (SNPs) in VDR are required to assess their relationships with breast cancer.

Vitamin D receptor gene polymorphisms and the risk for female reproductive cancers: A meta-analysis

Vitamin D receptor (VDR) gene polymorphisms and the risks for various breast and ovarian cancers have been reported in many epidemiological studies. However, the associations between VDR gene polymorphisms and the risk for each type of cancer are unclear. The aim of this meta-analysis was to evaluate the associations between VDR gene polymorphisms and female reproductive cancers. A systematic review was performed with the PubMed Science Direct, Scopus, and Google Scholar databases up to April 2014 using the search terms "vitamin D receptor or VDR" and "variant or polymorphism or SNP" with terms for breast, ovarian, cervical, endometrial, uterine, and vaginal cancers. A meta-analysis with the pooled odds ratios and 95% confidence intervals was carried out to assess the associations between VDR polymorphisms (Cdx-2, FokI, BsmI, ApaI, and TaqI) and the risks for reproductive cancers under the heterozygous, homozygous, dominant, and recessive models with fixed or random effects models. Six ovarian cancer studies (13 individual studies involving 4107 cases and 6661 controls) and 29 breast cancer studies (38 individual studies involving 16,453 cases and 22,044 controls) were included in our meta-analysis. Our results indicate that the FokI polymorphism was related to increased risks for breast and ovarian cancers, whereas the BsmI polymorphism was associated with a decreased risk for developing these cancers. Our comprehensive meta-analysis indicated that the FokI and BsmI VDR gene polymorphisms may be significantly associated with gynecological cancers. We suggest monitoring VDR gene polymorphisms as potential biomarkers in patients with gynecological malignancy.

Vitamin D receptor gene polymorphisms and steroid receptor status among Saudi women with breast cancer

The vitamin D receptor (VDR) is a mediator for the cellular effects of vitamin D and interacts with other cell signaling pathways that influence cancer development. We evaluated the associations of the FOK1 and Taq1 VDR polymorphisms and breast cancer risk and possible effect modification by steroid receptor status of the tumor. This case-control study includes 95 breast cancer patients and 100 age-matched controls. Genotyping for VDR FOK1 and Taq1 polymorphisms was performed using polymerase chain reaction-based restriction fragment length polymorphism. Level of 25(OH)D in serum was determined using ELISA. Immunohistochemical studies were performed for estrogen receptors (ER) and progesterone receptors (PR). The frequencies of ff genotype were significantly increased in the breast cancer group compared to the control group. Carriers of the f allele were significantly more likely to develop BC. We observed a statistically significant interaction for the Fok1 polymorphism and ER status. Our results demonstrated that FOK1 f. genotype and f allele have an important role in breast cancer risk in Saudi patients.

Association between VDR polymorphisms and breast cancer: an updated and comparative meta-analysis of crude and adjusted odd ratios

There is a lot of debate on the relationship between vitamin D receptor polymorphisms and risk of breast cancer. Herein, we quantitatively analyzed the published case-control studies on this relationship by meta- analysis, performing a bibliographic search from Pubmed and CNKI up to July 31, 2013. The included case- control studies for Fok1, Bsm1, Taq1, Apa1, Cdx2 and Poly-A were 16, 19, 20, 10, 4, 6, respectively. Crude and adjusted odd ratios and 95% confidence intervals were calculated to present and compare the strength of any associations. The results of combined analyses indicated that Fok1, Bsm1, Apa1, Cdx2 and Poly-A were not significantly associated with the risk of breast cancer. In contrast, the tt genotype of Taq1 was a modest risk factor for breast cancer development (tt vs. TT: OR = 1.21, 95% CI: 1.01-1.44). To further confirm the above results, adjusted effects for the six polymorphisms were pooled based on adjusted ORs reported in the original studies. Adjusted ORs of Fok1, Apa1, Cdx2 and Poly-A were similar to the crude ORs. However, Bsm1 and Taq1 showed inconsistent results. For Bsm1, OR for BB vs. bb was 0.85, 95% CI: 0.74-0.98; for Taq1, OR for tt vs. TT was 1.03, 95% CI: 0.92-1.15, and not associated with risk. Subgroup analyses for crude ORs showed some association between Bsm1, Taq1 and breast cancer in Caucasians only, but for adjusted ORs, no associations were found. This meta-analysis suggests that the roles that Fok1, Apa1, Cdx2 and Poly-A polymorphisms play in breast cancer risk are negligible, with Bsm1 and Taq1 as possible exceptions. To be conservative, we still assumed that they may play a modest role in determining breast cancer risk. Further studies are needed to validate our findings.

The role of the rs1544410 polymorphism of vitamin D receptor gene in breast cancer susceptibility

This study was devised to investigate the genetic effect modification of the BsmI polymorphism associated with the susceptibility to breast cancer. Case-control studies of the BsmI polymorphism and breast cancer were searched. A total of 17 eligible publications were included in our final analysis. Pooled ORs and 95 % CIs were obtained by means of fixed effects model. The general and stratified analyses according to ethnicity showed that the association between the BsmI polymorphism and the risk of breast cancer was not statistically significant. However, the subgroup of the hospital-based studies was found to confer protection against the disease (ORBBvs.bb = 0.83, 95 % CI = 0.71-0.97, P h = 0.571; OR BBvs.Bb+bb = 0.86, 95 % CI = 0.74-1.00, P h = 0.903; OR allele B vs. allele b = 0.92, 95 % CI = 0.86-0.99, P h = 0.337). Our results suggested that the presence of the BsmI polymorphism may contribute to the susceptibility of breast cancer. It is necessary that future large-scale studies should be conducted to further confirm the association between the BsmI polymorphism and breast cancer risk.

BsmI polymorphism of vitamin D receptor gene and cancer risk: a comprehensive meta-analysis

The VDR gene is an important regulator of the vitamin D pathway, and the role of some of its polymorphisms on cancer risk was previously investigated. A trend of cancer risk reduction with the VDR BsmI B allele was observed for many cancer sites. We performed a comprehensive meta-analysis to investigate the role of VDR BsmI polymorphism on cancer risk, even according to different ethnicities. Summary odds ratios (SORs) were calculated with random-effects models and maximum likelihood estimation. We categorized studies into three groups ("moderate", "high" and "very high confidence") according to departure from Hardy-Weinberg equilibrium in controls, reported minor allele frequency and genotyping quality controls. The meta-analysis included 73 studies with 45,218 cases and 52,057 controls. We found a significant 6-7% reduction of cancer risk at any site respectively for carriers of Bb genotype (SOR; 95%CI: 0.94; 0.90-0.99) and for carriers of BsmI BB genotype (SOR; 95%CI: 0.93; 0.89-0.98) compared to bb carriers, and they remain statistically significant when we restricted the analysis to at least "high confidence" studies. For skin cancer, a significant risk reduction was observed for Bb carriers (SOR; 95%CI: 0.86; 0.76-0.98). We also found a significant reduction of colorectal cancer risk for BB and Bb+BB genotypes carriers, but these SORs were no more significant when we restricted the analysis to studies with "high confidence". When the analysis was stratified by ethnicity, we still observed a significant decreased risk for both Bb and BB compared to bb genotype among Caucasians: SORs (95%CI) for any cancer site were 0.97 (0.93-1.00) and 0.95 (0.91-0.99), respectively. Among other ethnic groups the inverse association was still present, but did not reach statistical significance. In conclusion, we suggest a weak effect of BsmI B allele in reducing cancer risk at any site, especially of the skin.

VDR status arbitrates the prometastatic effects of tumor-associated macrophages

The relationship between tumor-associated macrophages (TAM) and epithelial-to-mesenchymal transition (EMT) during the initiation and progression of metastasis is still unclear. Here, a role for the vitamin D receptor (VDR) in metastasis was identified, as well as a role in the relationship between TAMs and EMT. First, the expression level of VDR was examined in clinical tissue from human patients with breast cancer or a mouse model of breast cancer with differential metastasis. These results revealed that VDR expression negatively correlates with metastasis in breast cancer. Second, coculture of VDR-overexpressing breast cancer cells with a macrophage cell line demonstrated that overexpression of VDR alleviated the prometastatic effect of cocultured macrophages on breast cancer cells. Furthermore, VDR overexpression abrogated the induction of EMT in breast cancer cells by cocultured macrophage cells, as measured by a loss of E-cadherin (CDH1) and induction of α-smooth muscle actin (α-SMA). TNFα in macrophage conditioned media inhibited VDR expression, whereas downregulation of VDR further mediated the promotion of TGFβ-induced EMT by TNFα. In addition, β-catenin expression was inhibited in VDR-overexpressing breast cancer cells and tumor xenografts. Finally, administration of calcitriol [1,25-(OH)2D3], an active vitamin D metabolite, exerted similar antimetastatic effects in breast cancer cells in vitro and a mouse model of breast cancer in vivo with preservation of VDR and suppression of β-catenin.

IMPLICATIONS

VDR suppression by TNFα mediates the prometastatic effect of TAMs through enhancement of the β-catenin pathway.

Association between vitamin D receptor gene polymorphisms and breast cancer risk: a meta-analysis of 39 studies

Background

The associations between vitamin D receptor (VDR) gene polymorphisms and breast cancer risk were comprehensively investigated to clarify issues that remain controversial.

Methodology/Principal Findings

An electronic search was conducted of several databases, including PubMed, the Cochrane library, Web of Science, EMBASE, CBM and CNKI, for papers that describe the association between Fok1, poly-A repeat, Bsm1, Taq1 or Apa1 polymorphisms of the VDR gene and breast cancer risk. Summary odds ratios and 95% confidence intervals (CI) were estimated based on a fixed-effect model (FEM) or random-effect model (REM), depending on the absence or presence of significant heterogeneity. A total of 39 studies met the inclusion criteria. A meta-analysis of high-quality studies showed that the Fok1 polymorphism of the VDR gene was associated with an increased risk of breast cancer (ff vs. Ff+FF, OR: 1.09, 95%CI: 1.02 to 1.16, p = 0.007). No significant associations were observed between the other polymorphisms and breast cancer risk. No positive results were detected by pooling the results of all relevant studies.

Conclusion

A meta-analysis of high-quality studies demonstrated that the Fok1 polymorphism of the VDR gene was closely associated with breast cancer risk.

Vitamin D receptor FokI gene polymorphisms may be associated with colorectal cancer among African American and Hispanic participants

BACKGROUND

Vitamin D plays a role in cancer tumorogenesis and acts through the vitamin D receptor (VDR). Although African Americans have the lowest serum vitamin D levels, supplementation has not yielded a significant improvement in cancer. Gene polymorphisms in VDR may play a role. There is a dearth of information on VDR gene polymorphisms and colorectal cancer (CRC) among under-represented ethnic groups. In this study, the authors examined whether VDR gene single nucleotide polymorphisms (SNPs) were associated with CRC in predominately African American and Hispanic study participants.

METHODS

Blood samples were collected from 378 participants, including a group of 78 patients with CRC (cases), a group of 230 noncancer participants without polyps (controls without polyps), and a group of 70 noncancer participants with polyps (controls with polyps). The 4 polymorphic SNPs in VDR (FokI, BsmI, TaqI, and ApaI) were assessed using the polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

There was a significant association of the VDR-FokI FF genotype with CRC cases (odds ratio, 2.9; P= .036) compared with the controls without polyps. The most common VDR-FokI genotype in the overall study population was the FF genotype (46%). However, upon breakdown by ethnicity, the FF genotype was the most common in African American participants (61%), and the Ff genotype was the most common in Hispanic/Latino participants (49%). When the association was assessed in a multivariate model, there was no significant association with any VDR polymorphism and CRC cases (P> .05). The other 3 polymorphic variants of VDR (BsmI, TaqI, and ApaI) were not associated with CRC.

CONCLUSIONS

The results from this study suggest that genetic variation of the VDR-FokI SNPs may influence CRC risk, particularly in African American cohorts.

Plasma 25-hydroxyvitamin D3 is associated with decreased risk of postmenopausal breast cancer in whites: a nested case-control study in the multiethnic cohort study

BACKGROUND

Higher sunlight exposure is correlated with lower incidence of breast cancer in ecological studies, but findings from prospective studies regarding the association of circulating levels of vitamin D with the risk of breast cancer have been null. The objective of this study was to examine the relation between plasma levels of vitamin D and the risk of postmenopausal breast cancer.

METHODS

We conducted a nested case-control study within the Multiethnic Cohort Study of five race/ethnic groups (white, African-American, Native Hawaiian, Japanese, and Latino) from Hawaii and Los Angeles between 2001 and 2006. Pre-diagnostic plasma levels of 25-hydroxyvitamin D2 [25(OH)D2], 25-hydroxyvitamin D3 [25(OH)D3] and 25(OH)D (sum of 25(OH)D2 and 25(OH)D3) were examined among 707 postmenopausal breast cancer cases and matched controls.

RESULTS

Using conditional logistic regression models, 20 ng/mL increases of plasma 25(OH)D3 (odds ratio (OR) 0.28; 95% confidence interval (CI) 0.14-0.56) and 25(OH)D (OR 0.43; 95% CI 0.23-0.80) were inversely associated with breast cancer risk among white women, but not among women in other race/ethnic groups. Using two-segmented, piecewise-linear logistic regression models, the change-points of the ORs, either for 25(OH)D3 or for 25(OH)D, were detected as 20 ng/mL among whites.

CONCLUSIONS

Circulating 25(OH)D3 and 25(OH)D were associated with a reduced risk of postmenopausal breast cancer among whites, but not in other ethnic groups, who reside in low latitude regions.

Current evidence on the four polymorphisms of VDR and breast cancer risk in Caucasian women

There have been a few epidemiological studies reporting VDR polymorphisms including Fok1, Bsm1, Apa1 and Taq1with breast cancer incidence and therefore risk. The results however are controversial, often due to smaller sample size. Concerning most of the studies were performed on Caucasian women, we conducted this comprehensive meta-analysis encompassing 38,151 cases and 47,546 controls (Fok1: 13,152 cases, 17,443 controls; Bsm1: 14,755 cases, 18,633 controls; Apa1: 3080 cases, 3412 controls; Taq1: 7164 cases, 8068 controls) to better understand roles of the polymorphisms in breast cancer development among Caucasian population. We did not find any association of the most controversial genotype Fok1 with breast cancer risk in Caucasian women (ff vs. FF: OR = 1.05, 95% CI = 0.95–1.22, P = 0.32 for heterogeneity; ff vs. Ff: OR = 1.05, 95% CI = 0.94–1.17, P = 0.40; ff vs. Ff + FF: OR = 1.07, 95% CI = 0.95–1.14, P = 0.37 and ff + Ff vs. FF: OR = 1.04, 95% CI = 0.99–1.09, P = 0.23). For Bsm1, Apa1 and Taq1, no significant association was also not found in the homozygote comparison, heterozygote comparison, recessive and dominant models respectively. In conclusion, the current analysis suggested that the four polymorphisms (Fok1, Bsm1, Apa1 and Taq1) of VDR may be not associated with breast cancer risk in Caucasian women.

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We added some new studies.

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The polymorphisms of VDR gene do not contribute to breast cancer susceptibility.

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This analysis is conducted in Caucasian women.

Vitamin D receptor gene polymorphisms in breast and renal cancer: current state and future approaches (review)

Cancer is a major health problem and cause of death worldwide that accounted for 7.6 million deaths in 2008, which is projected to continue rising with an estimated 13.1 million deaths in 2030 according to WHO. Breast cancer is the leading cause of cancer-based death among women around the world and its incidence is increasing annually with a similar tendency. In contrast, renal cell carcinoma accounts for only 3% of total human malignancies but it is still the most common type of urological cancer with a high prevalence in elderly men (>60 years of age). There are several factors linked with the development of renal cell cancer only, while others are connected only with breast cancer. Genetic risk factors and smoking are the factors which contribute to carcinogenesis in general. Some evidence exists indicating that vitamin D receptor (VDR) gene polymorphisms are associated with both breast and renal cancer; therefore, we put forward the hypothesis that polymorphisms in the VDR gene may influence both the occurrence risks of these cancers and their prognosis. However, the relationship between VDR polymorphisms and these two specific cancers remains a controversial hypothesis, and consequently needs further confirmation via clinical research together with genetic investigations. Here, we aimed to assess the correlation between the different alleles of VDR gene polymorphisms and renal cell cancer and breast cancer risks separately through a systematic review of the present literature. In contrast, this analysis has revealed that some VDR gene polymorphisms, such as: Bsm1, poly(A), Taq1, Apa1, are to some extent associated with breast cancer risk. Other polymorphisms were found to be significantly associated with renal cell cancer. Namely, they were Fok1, Bsm1, Taq1 and Apa1, which encode proteins participating mainly in proliferation, apoptosis and cell cycle regulation. However, data concerning renal cancer are not sufficient to firmly establish the VDR gene polymorphism association.

Association between vitamin D receptor poly(A) polymorphism and breast cancer risk: a meta-analysis

Vitamin D receptor (VDR) poly(A) is a common genetic polymorphism in the VDR gene, and it has been implicated to be associated with breast cancer risk. However, previous studies on the association reported inconclusive results. We performed this meta-analysis to comprehensively assess the association. Eligible studies were searched in PubMed and EMBASE databases. Odds ratio (OR) and its 95% confidence interval (95% CI) were used for statistical analysis. A total 6,631 cases and 6,718 controls from 11 case-control studies were finally included into the meta-analysis. Meta-analysis of total eligible studies showed that VDR poly(A) polymorphism was not associated with the risk of breast cancer (S versus L: OR = 0.99, 95% CI of 0.90-1.09, P = 0.84; SS versus LL: OR = 0.96, 95% CI of 0.79-1.18, P = 0.70; SS/LS versus LL: OR = 0.96, 95% CI of 0.83-1.12, P = 0.63; SS versus LL/LS: OR = 1.00, 95% CI of 0.91-1.10, P = 0.98). Meta-analysis of studies with high quality also showed that there was no association between VDR poly(A) polymorphism and breast cancer risk. In addition, in the subgroup analysis by ethnicity, no significant association was found among Caucasians. Therefore, the meta-analysis suggests that VDR poly(A) polymorphism is not associated with the risk of breast cancer. Large well-designed studies are necessary to clarify the possible association in Asians.

Associations between vitamin D receptor polymorphisms and breast cancer risk

Many epidemiologic studies have investigated the association between vitamin D receptor (VDR) gene polymorphisms and breast cancer risk, but the results were inconsistent. We performed a meta-analysis of 31 studies on VDR polymorphisms, including FokI, BsmI, TaqI, and ApaI, and breast cancer risk published before May 2013. For FokI, the allele of f was found to be associated with increased risk of breast cancer compared with F (OR, 1.19; 95% CI, 1.03-1.36). Patients with ff genotype were at significantly higher risk of breast cancer compared with those with FF genotype (OR, 1.95; 95% CI, 1.66-2.29). In subgroup analysis by race, Fok1 polymorphism was significantly associated with breast cancer risk for Caucasian population (f vs. F: OR, 1.35; 95% CI, 1.14-1.59; ff vs. FF: OR, 2.18; 95% CI, 1.86-2.54; ff vs. FF + Ff: OR, 1.16; 95% CI, 1.03-1.30). For ApaI, aa genotype was associated with increased breast cancer risk in Asian population based on four studies (aa vs. Aa + AA, OR, 1.49; 95% CI, 1.12-1.98). No significant association was found between breast cancer risk and ApaI and TaqI polymorphism in different models and populations. Our updated meta-analysis showed that Fok1 polymorphism is associated with breast cancer risk both in general population and in Caucasian population. ApaI polymorphism might be associated with breast cancer risk in Asian population. Large well-designed epidemiological studies are necessary to clarify the risk identified in the current meta-analysis.

Risk factors of breast cancer: a systematic review and meta-analysis

The etiology of breast cancer might be explained by 2 mechanisms, namely, differentiation and proliferation of breast epithelial cells mediated by hormonal factors. We performed a systematic review and meta-analysis to update effects of risk factors for both mechanisms. MEDLINE and EMBASE were searched up to January 2011. Studies that assessed association between oral contraceptives (OC), hormonal replacement therapy (HRT), diabetes mellitus (DM), or breastfeeding and breast cancer were eligible. Relative risks with their confidence intervals (CIs) were extracted. A random-effects method was applied for pooling the effect size. The pooled odds ratios of OC, HRT, and DM were 1.10 (95% CI = 1.03-1.18), 1.23 (95% CI = 1.21-1.25), and 1.14 (95% CI = 1.09-1.19), respectively, whereas the pooled odds ratio of ever-breastfeeding was 0.72 (95% CI = 0.58-0.89). Our study suggests that OC, HRT, and DM might increase risks, whereas breastfeeding might lower risks of breast cancer.

The association between the poly(A) polymorphism in the VDR gene and cancer risk: a meta-analysis

The poly(A) polymorphism (L/S) in the VDR gene has been implicated in susceptibility of cancer, but a number of studies have reported inconclusive results. The aim of this study is to investigate the relationship between the poly(A) polymorphism in the VDR gene and cancer risk by meta-analysis. We searched PubMed database, EMBASE database, CNKI database, and Wanfang database, covering all studies until January 22, 2013. Statistical analysis was performed by using the software Revman4.2 and STATA 10.0. A total 8,186 cancer cases and 8,685 controls in 19 case-control studies from 15 studies were identified for data analysis. The results suggested that the S allele carriers (SS+SL) did not have an increased or decreased risk of cancer when compared with the homozygote LL carriers (odds ratio (OR) =0.96, 95 % CI=0.87-1.06, P=0.43 for SS+SL vs. LL). In addition, in the subgroup analysis by ethnicity and cancer type, no significant association was found among Caucasians, African-Americans, prostate cancer, or breast cancer. This current meta-analysis suggested that the poly(A) polymorphism in the VDR gene may not contribute to the risk of cancer. Future studies are needed to validate our findings.

Vitamin D receptor gene polymorphisms and prognosis of breast cancer among African-American and Hispanic women

BACKGROUND

Vitamin D plays a role in cancer development and acts through the vitamin D receptor (VDR). Although African-Americans have the lowest levels of serum vitamin D, there is a dearth of information on VDR gene polymorphisms and breast cancer among African-Americans and Hispanics. This study examines whether VDR gene polymorphisms are associated with breast cancer in these cohorts.

METHODS

Blood was collected from 232 breast cancer patients (Cases) and 349 non-cancer subjects (Controls). Genotyping for four polymorphic variants of VDR (FokI, BsmI, TaqI and ApaI) was performed using the PCR-RFLP method.

RESULTS

An increased association of the VDR-Fok1 f allele with breast cancer was observed in African-Americans (OR = 1.9, p = 0.07). Furthermore, the FbTA, FbtA and fbtA haplotypes were associated with breast cancer among African-Americans (p<0.05). Latinas were more likely to have the VDR-ApaI alleles (Aa or aa) (p = 0.008). The VDR-ApaI aa genotype was significantly associated with poorly-differentiated breast tumors (p = 0.04) in combined Cases. Kaplan-Meier survival analysis showed decreased 5-year disease-free-survival (DFS) in breast cancer patients who had the VDR-Fok1 FF genotype (p<0.05). The Cox regression with multivariate analysis revealed the independent predictor value of the VDR-FokI polymorphism for DFS. The other three variants of VDR (BsmI, TaqI and ApaI) were not associated with disease outcome.

CONCLUSIONS

VDR haplotypes are associated with breast cancer in African-Americans, but not in Hispanic/Latinas. The VDR-FokI FF genotype is linked with poor prognosis in African-American women with breast cancer.

Vitamin d: are we ready to supplement for breast cancer prevention and treatment?

Vitamin D deficiency is a potentially modifiable risk factor that may be targeted for breast cancer prevention and treatment. Preclinical studies support various antitumor effects of vitamin D in breast cancer. Numerous observational studies have reported an inverse association between vitamin D status, including circulating 25-hydroxyvitamin D (25(OH)D) levels, and breast cancer risk. The relationship between vitamin D and mammographic density, a strong predictor of breast cancer risk, remains unclear. Studies analyzing the link between genetic polymorphisms in vitamin D pathway genes and breast cancer incidence and prognosis have yielded inconsistent results. Vitamin D deficiency among breast cancer patients has been associated with poorer clinical outcomes and increased mortality. Despite a number of clinical trials of vitamin D supplementation, the efficacy, optimal dosage of vitamin D, and target blood level of 25(OH)D for breast cancer prevention have yet to be determined. Even with substantial literature on vitamin D and breast cancer, future studies need to focus on gaining a better understanding of the biologic effects of vitamin D in breast tissue. Despite compelling data from experimental and observational studies, there is still insufficient data from clinical trials to make recommendations for vitamin D supplementation for breast cancer prevention or treatment.

Down-regulation of vitamin D receptor in mammospheres: implications for vitamin D resistance in breast cancer and potential for combination therapy

Vitamin D signaling in mammary cancer stem cells (MCSCs), which are implicated in the initiation and progression of breast cancer, is poorly understood. In this study, we examined vitamin D signaling in mammospheres which are enriched in MCSCs from established breast cancer cell lines. Breast cancer cells positive for aldehyde dehydrogenase (ALDH(+)) had increased ability to form mammospheres compared to ALDH(-) cells. These mammospheres expressed MCSC-specific markers and generated transplantable xenografts in nude mice. Vitamin D receptor (VDR) was significantly down-regulated in mammospheres, as well as in ALDH(+) breast cancer cells. TN aggressive human breast tumors as well as transplantable xenografts obtained from SKBR3 expressed significantly lower levels of VDR but higher levels of CD44 expression. Snail was up-regulated in mammospheres isolated from breast cancer cells. Inhibition of VDR expression by siRNA led to a significant change in key EMT-specific transcription factors and increased the ability of these cells to form mammospheres. On the other hand, over-expression of VDR led to a down-regulation of Snail but increased expression of E-cad and significantly compromised the ability of cells to form mammospheres. Mammospheres were relatively insensitive to treatment with 1,25-dihydroxyvitamin D (1,25D), the active form of vitamin D, compared to more differentiated cancer cells grown in presence of serum. Treatment of H-Ras transformed HMLE(HRas) cells with DETA NONOate, a nitric oxide (NO)-donor led to induction of MAP-kinase phosphatase -1 (MKP-1) and dephosphorylation of ERK1/2 in the mammospheres. Combined treatment of these cells with 1,25D and a low-concentration of DETA NONOate led to a significant decrease in the overall size of mammospheres and reduced tumor volume in nude mice. Our findings therefore, suggest that combination therapy using 1,25D with drugs specifically targeting key survival pathways in MCSCs warrant testing in prospective clinical trial for treatment of aggressive breast cancer.

Vitamin D receptor (VDR) polymorphisms and risk of ovarian cancer in Caucasian and African American women

OBJECTIVE

Polymorphisms in the vitamin D receptor (VDR) gene have been shown in some studies to be associated with the risk of epithelial ovarian cancer (EOC) in Caucasian women. There are no published reports among African Americans.

METHODS

Case-control data from the North Carolina Ovarian Cancer Study were analyzed using logistic regression to determine the association between seven VDR polymorphisms and EOC in both Caucasians (513 cases, 532 controls) and African Americans (74 cases, 79 controls). In a larger sample of African-Americans (125 cases, 155 controls), we assessed associations between six SNPs in proximity of rs7975232.

RESULTS

African American women who carried at least one minor allele of rs7975232 were at higher risk for invasive EOC controlling for age and admixture with an odds ratio (OR) for association under the log-additive model of 2.08 (95% confidence interval (CI)=1.19, 3.63, p=0.010). No association was observed between any of the VDR variants and EOC among Caucasians. A larger sample of African Americans revealed a nearly two-fold increased risk of invasive EOC associated with rs7305032, a SNP in proximity to rs7975232 (R(2)=0.369) with a log-additive OR of 1.87 (95% CI=1.20, 2.93, p=0.006).

CONCLUSIONS

This is the first report showing VDR variants associated with ovarian cancer risk in African American women. A larger study of African American women is needed to confirm these findings. These results imply that vitamin D exposure is a possible modifiable risk factor of ovarian cancer among African Americans.

Vitamin D receptor gene haplotypes and polymorphisms and risk of breast cancer: a nested case-control study

BACKGROUND

Observational and experimental studies suggest that vitamin D may influence breast cancer etiology. Most known effects of vitamin D are mediated via the vitamin D receptor (VDR). Few polymorphisms in the VDR gene have been well studied in relation to breast cancer risk and results have been inconsistent.

METHODS

We investigated VDR polymorphisms and haplotypes in relation to breast cancer risk by genotyping 26 single nucleotide polymorphisms (SNP) that (i) had known/suspected impact on VDR function, (ii) were tagging SNPs for the three VDR haplotype blocks among whites, or (iii) were previously associated with breast cancer risk. We estimated odds ratios (OR) and 95% confidence intervals (CI) in relation to breast cancer risk among 270 incident cases and 554 matched controls within the Agricultural Health Study cohort.

RESULTS

In individual SNP analyses, homozygous carriers of the minor allele for rs2544038 had significantly increased breast cancer risk (OR = 1.5; 95% CI: 1.0-2.5) and homozygous carriers of the minor allele for rs11168287 had significantly decreased risk (OR = 0.6; 95% CI: 0.4-1.0). Carriers of the minor allele for rs2239181 exhibited marginally significant association with risk (OR = 1.4; 95% CI: 0.9-2.0). Haplotype analyses revealed three haplotype groups (blocks "A," "B," and "C"). Haplotype GTCATTTCCTA in block B was significantly associated with reduced risk (OR = 0.5; 95% CI: 0.3-0.9).

CONCLUSIONS

These results suggest that variation in VDR may be associated with breast cancer risk.

IMPACT

Our findings may help guide future research needed to define the role of vitamin D in breast cancer prevention.

Vitamin D receptor, CYP27B1 and CYP24A1 genes polymorphisms association with oral cancer risk and survival

BACKGROUND

Genetic polymorphisms of vitamin D receptor gene (VDR) and genes involved in vitamin D metabolism pathway, CYP27B1 and CYP24B1, may affect individual susceptibility to oral squamous cell carcinoma. The purpose of this study was to evaluate the associations between VDR, CYP27B1 and CYP24A1 gene polymorphisms with oral cancer risk and survival.

METHODS

Study cohort consisted of 110 patients with oral cancer and 122 healthy controls. The genotypes of the analysed genes were determined by PCR-RFLP or real-time PCR method.

RESULTS

The significant decrease of oral cancer risk was observed in individuals with heterozygote genotype of CYP24A1 gene (rs2296241) (odds ratio 0.281, P = 0.000) in comparison with wild type. Patients with VDR FokI ff wild type genotype had significantly worse overall survival (P = 0.012, log rank) compared with heterozygous and mutated genotype combined. A stratified analysis by the lymph node involvement and tumour stage showed that ff is associated with poor survival in groups with and without lymph node involvement (P = 0.025, P = 0.040, respectively) and in stage III tumours (P = 0.026). Multivariate Cox's regression analysis revealed that VDR FokI could be considered an independent prognostic factor.

CONCLUSION

Our findings indicate that CYP24A1 gene polymorphism might have an influence on the susceptibility to oral cancer. VDR FokI polymorphism was associated with worse survival and could be considered as an independent prognostic marker.

Variants in the vitamin D pathway, serum levels of vitamin D, and estrogen receptor negative breast cancer among African-American women: a case-control study

Introduction

American women of African ancestry (AA) are more likely than European Americans (EA) to have estrogen receptor (ER)-negative breast cancer. 25-hydroxyvitamin D (25OHD) is low in AAs, and was associated with ER-negative tumors in EAs. We hypothesized that racial differences in 25OHD levels, as well as in inherited genetic variations, may contribute, in part, to the differences in tumor characteristics.

Methods

In a case (n = 928)-control (n = 843) study of breast cancer in AA and EA women, we measured serum 25OHD levels in controls and tested associations between risk and tag single nucleotide polymorphisms (SNPs) in VDR, CYP24A1 and CYP27B1, particularly by ER status.

Results

More AAs had severe vitamin D deficiency (< 10 ng/ml) than EAs (34.3% vs 5.9%), with lowest levels among those with the highest African ancestry. Associations for SNPs differed by race. Among AAs, VDR SNP rs2239186, associated with higher serum levels of 25OHD, decreased risk after correction for multiple testing (OR = 0.53, 95% CI = 0.31-0.79, p by permutation = 0.03), but had no effect in EAs. The majority of associations were for ER-negative breast cancer, with seven differential associations between AA and EA women for CYP24A1 (p for interaction < 0.10). SNP rs27622941 was associated with a > twofold increased risk of ER-negative breast cancer among AAs (OR = 2.62, 95% CI = 1.38-4.98), but had no effect in EAs. rs2209314 decreased risk among EAs (OR = 0.38, 95% CI = 0.20-0.73), with no associations in AAs. The increased risk of ER-negative breast cancer in AAs compared to EAs was reduced and became non-significant (OR = 1.20, 95% CI = 0.80-1.79) after adjusting for these two CYP24A1 SNPs.

Conclusions

These data suggest that genetic variants in the vitamin D pathway may be related to the higher prevalence of ER-negative breast cancer in AA women.

The association between vitamin D receptor expression and prolonged overall survival in breast cancer

In this study, we analyzed vitamin D receptor (VDR) expression and survival in a breast cancer patient cohort of 82 breast cancer patients. Immunohistochemical analysis was possible in 91.5% of the patients (75/82). Staining was evaluated using the semi-quantitative assay according to Remmele and Stegner (immunoreactivity score [IRS]). IRS 0-1 was negative/very low, IRS 2-4 was moderate to high, and IRS 6-12 was high. Statistical analysis was performed by Spearman's correlation test (p<0.05 significant). Overall survival was analyzed using Kaplan-Meier estimations. Only 6 patients had a negative IRS. Moderate IRS values were present in 20 patients. Most of the patients had a high IRS (49). For survival analysis, data were dichotomized (IRS 0-4: negative to moderate and IRS 6-12: high VDR expression). In univariate analysis, VDR expression showed significant differences in progression-free survival (PFS) and overall survival (OS). Patients with high IRS scores showed significantly better PFS and OS than patients with moderate/negative IRS scores for VDR expression. Tumor size was significantly correlated to PFS. When analyzed separately, the three different IRS groups showed significant differences in VDR expression. The present data suggest that VDR expression in breast cancer tissue may be of clinical significance, and the results provide evidence that VDR may be a factor with prognostic relevance.

Case-control study of vitamin D, dickkopf homolog 1 (DKK1) gene methylation, VDR gene polymorphism and the risk of colon adenoma in African Americans

BACKGROUND

There are sparse data on genetic, epigenetic and vitamin D exposure in African Americans (AA) with colon polyp. Consequently, we evaluated serum 25(OH) D levels, vitamin D receptor (VDR) polymorphisms and the methylation status of the tumor suppressor gene dickkopf homolog 1 (DKK1) as risk factors for colon polyp in this population.

METHODS

The case-control study consisted of 93 patients with colon polyp (cases) and 187 healthy individuals (controls) at Howard University Hospital. Serum levels of 25(OH)D (including D3, D2, and total) were measured by liquid chromatography-mass spectrometry. DNA analysis focused on 49 single nucleotide polymorphisms (SNPs) in the VDR gene. Promoter methylation analysis of DKK1 was also performed. The resulting data were processed in unadjusted and multivariable logistic regression analyses.

RESULTS

Cases and controls differed in vitamin D status (D(3)<50 nmol/L: Median of 35.5 in cases vs. 36.8 in controls nmol/L; P = 0.05). Low levels of 25(OH)D(3) (<50 nmol/L) were observed in 86% of cases and 68% of controls and it was associated with higher risks of colon polyp (odds ratio of 2.7, 95% confidence interval 1.3-3.4). The SNP analysis showed no association between 46 VDR polymorphisms and colon polyp. The promoter of the DKK1 gene was unmethylated in 96% of the samples.

CONCLUSION

We found an inverse association between serum 25(OH)D(3) and colon polyp in AAs. VDR SNPs and DKK1 methylation were not associated with colon polyp. Vitamin D levels may in part explain the higher incidence of polyp in AAs.

Genetic variation in proinflammatory cytokines IL6, IL6R, TNF-region, and TNFRSF1A and risk of breast cancer

Proinflammatory cytokines are associated with age-related diseases including arthritis and heart disease. IL6 and TNF also play key roles in estrogen modulation in older women. We explored whether variation in IL6 and TNF genes influenced the risk of breast cancer in samples that differed by age group: <44 years (228 cases and 271 controls), 45-64 years (426 cases and 396 controls), and 65+ years (228 cases and 239 controls). Samples were drawn from population-based case-control studies conducted in Seattle. Age-adjusted odds ratios (ORs) were calculated to evaluate the risk associated with variants in IL6, IL6R, TNF, and TNFRSF1A. There was a significantly increased risk of breast cancer associated with one or more C>T alleles at IL6 rs2069861 among subjects in the oldest age group (OR 1.8, 95% CI 1.1-2.9), but no overall increased risk of breast cancer associated with any IL6 or IL6R variants in the combined data. There were significantly elevated risks of breast cancer among women 45-64 years old associated with a UTR 5' flanking SNP LTA rs2009658 C>G allele (OR 1.5, 95% CI 1.1-1.9) and a nonsynonomous coding SNP TNFRSF1A rs767455 T>C allele (OR 1.3, 95% CI 1.1-1.6); these two variants were also elevated in the combined data (OR 1.3, 95% CI 1.1-1.5 and OR 1.2, 95% CI 1.1-1.4, respectively). This study supports a modest association between a variant in IL6 and breast cancer among older women and TNF-related variants and breast cancer among middle-aged women. Further evaluation of these genes in other studies is warranted.