Vitamin D receptor variants and breast cancer risk in the Polish population

The VDR rs1544410 and rs11568820 Variants and the Risk of Osteoporosis in the Polish Population

Vitamin D affects bone metabolism and calcium-phosphate metabolism. Its deficiency leads to bone mineralization disorders and is the cause of abnormal skeletal development from fetal life to the period of completed skeletal growth. In later periods of life, vitamin D deficiency leads to bone metabolism disorders, i.e., osteoporosis. Disturbance of the balance between osteoblasts responsible for bone formation and osteoclasts associated with bone resorption results in reduced bone mass and bone weakening, and consequently leads to susceptibility to fractures. Analysis of genetic variants of the vitamin D receptor (VDR) concerns their relationship with metabolic bone diseases, and the results of previous studies assessing the relationship of polymorphisms with bone mineral density, fracture risk, or osteoporosis are not clear. Therefore, the aim of our study was to determine the effect of rs1544410 and rs11568820 polymorphisms of the VDR gene on the risk of developing osteoporosis in the Polish population. The study included 197 women with osteoporosis, 98 women with osteopenia, and 147 healthy controls. The real-time PCR method was used to determine the rs1544410 and rs11568820 polymorphisms of the VDR1 gene. Analysis of the results in the group with osteopenia showed that for the rs1544410 polymorphism, heterozygous GA genotypes occurred in 37.8% of the study group and 47.6% of the controls (OR = 0.60; 95%CI: 0.34-1.05), and homozygous AA in 15.3% of the study group and 17.0% of the controls (OR = 0.68; 95%CI: 0.32-1.44) (p = 0.185, AIC = 332.4; AIC-Akaike information criterion). The best model for this variant turned out to be the dominant model OR = 0.62; 95%CI: 0.37-1.04; p = 0.071, AIC = 330.5. In the case of the rs11568820 polymorphism of the VDR gene, the GG genotype was more common in women with osteopenia compared to controls (75.5% vs. 70.1%). Genotypes containing at least one mutant A allele were present in 24.5% of women with osteopenia and 29.9% of controls (OR = 0.76; 95%CI: 0.43-1.36; p = 0.349; AIC = 332.9). Analyzing the rs1544410 polymorphism in women with osteoporosis, the GA genotype was present in 42.1% of the study group and 47.6% of patients with normal bone density (OR = 0.74; 95%CI: 0.46-1.19), and the AA genotype in 15.7% of the study group and 17.0% of controls (OR = 0.78; 95%CI: 0.41-1.46) (p = 0.441). In the case of the rs11568820 polymorphism, the GA genotype occurred in 22.3% of the study subjects and 27.2% of the control patients (OR = 0.76; 95%CI: 0.46-1.25), and the AA genotype in 2.0% of the study subjects and 2.7% of the controls (OR = 0.69; 95%CI: 0.17-2.83) (p = 0.511). For both variants, the model with the lowest AIC value was the dominant model, in which for the rs1544410 variant OR = 0.75; 95%CI: 0.48-1.17; p = 0.203; AIC = 472.0 was obtained, while for rs11568820-OR = 0.75; 95%CI: 0.47-1.22; p = 0.250; AIC = 472.3. The obtained results indicate that the rs1544410 and rs11568820 polymorphisms of the VDR gene do not affect the development of osteoporosis in the Polish population.

Vitamin D receptor polymorphisms associate with the efficacy and toxicity of radioiodine-131 therapy in patients with differentiated thyroid cancer

BACKGROUND

Radioiodine-131 (I-131) therapy is the common postoperative adjuvant therapy for differentiated thyroid cancer (DTC) However, methods to evaluate the efficacy and toxicity of I-131 on DTC are still lacking.

OBJECTIVE

To evaluate the association between vitamin D receptor (VDR) gene polymorphisms and the efficacy and toxicity of I-131 in DTC patients.

METHODS

A total of 256 DTC patients who received I-131 therapy were enrolled. The patients were divided into effective group and ineffective group. 4 single nucleotide polymorphisms (SNPs) (rs7975232, rs731236, rs1544410 and rs10735810) of VDR were analyzed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) Cell counting kit-8 (CCK-8) and flow cytometry were used to detect the proliferation and apoptosis of thyroid cancer cells.

RESULTS

Patients in effective group had more CC genotype of rs7975232 and GG genotype of rs10735810 compared with patients in ineffective group They were also independent factors for influencing the efficacy of I-131. PTC-1 and FTC-133 cells transfected with CC genotype of rs7975232 showed lower proliferative activity and higher apoptosis rate after being treated with I-131 In addition, patients with CC genotype at rs7975232 had fewer adverse reactions after I-131 treatment.

CONCLUSIONS

VDR gene polymorphisms may be associated with the efficacy and toxicity of I-131 in DTC patients, which will help to personalize the treatment for patients.

Lower vitamin D levels and VDR variants are risk factors for breast cancer: an updated meta-analysis

Inadequate vitamin D levels and vitamin D variants have been shown to be associated with breast cancer (BC), however the results are inconsistent. To reach a definitive conclusion the present meta-analysis was conducted. When compared to healthy controls, BC patients had reduced vitamin D levels (standard difference in means = -0.564, p = 0.003). The meta-analysis revealed that the FokI mutation was linked with an increased BC susceptibility (CC vs. TT: OR = 1.107, p = 0.001, CC vs. TC + TT: OR = 1.114, p = 0.020). There was no role of other VDR variants (BsmI, TaqI, and ApaI). FokI mutation and diminished vitamin D increase the likelihood of developing BC.

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.

Genetic Polymorphisms of Vitamin D Receptor Gene are Associated with Cervical Cancer Risk in Northeastern Thailand

OBJECTIVE

This study aimed to explore whether VDR polymorphisms (Fok1, Apa1 and Taq1) are associated to the cervical cancer in Thai population.

MATERIALS AND METHODS

Subjects of 204 cervical cancer patient and 204 age-matched healthy control were enrolled in the case-control study. VDR polymorphisms were detected by using real-time PCR. Haplotype analysis of three loci was applied to the obtained genotypes.

RESULTS

Significantly increased risk for cervical cancer was observed in carriers of TT genotype (p = 0.0388) and T allele (p = 0.0357) of Fok1 and TC genotype (p = 0.0001), CC genotype (p = 0.0160) and the C allele of Taq1 (p = 0.0001). Haplotype analyses revealed a significant correlation between C-T-C, T-G-C and T-T-C haplotypes and elevated risk for cervical cancer (OR = 2.06; 95%CI = 1.06-4.00; p = 0.0313, OR = 2.15; 95%CI = 1.22-3.80; p = 0.0078 and OR = 2.81; 95%CI = 1.53-5.16; p = 0.0006, respectively). Furthermore, haplotype carrying C allele of Taq1 (C-G-C + C-T-C + T-G-C + T-T-C) significantly increased cervical cancer risk with OR of 1.92 (95%CI = 1.32-2.79, p = 0.0006).

CONCLUSION

Our finding revealed an association between VDR polymorphisms and cervical cancer risk. Taq1 C allele might be a molecular marker for cervical cancer development.<br />.

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.

Medullary thyroid cancer is associated with high serum vitamin D level and polymorphism of vitamin D receptors

Background

Thyroid cancer is the most common endocrine malignancy. Studies have observed an anti-cancer effect for vitamin D and found that polymorphisms of vitamin D receptors can influence the prevalence of various cancers. The present study investigated the serum level of vitamin D and FokI, BsmI and Tru9I polymorphisms of vitamin D receptors.

Methods

Forty patients with medullary thyroid cancer and 40 healthy controls were investigated. The genomic DNA of the subjects was extracted using saturated salt/proteinase K and investigated by PCR sequencing. Serum levels of vitamin D were evaluated by ELISA. The results were analyzed in SPSS and GraphPad Prism 5 software.

Results

The genotypic and allelic frequencies of FokI and BsmI polymorphisms showed no significant differences between test and control groups. For Tru9I polymorphism, Tt genotype and t allelic frequency in the test group were significantly different from those of the control group. Also, we found Tt genotype and t allelic frequency to be significantly associated with medullary thyroid cancer (MTC) type and the agressiveness of the disease. The average serum vitamin D level was 23.32 ng/mL and 18.95 ng/mL for patients and controls, respectively, and the difference between the two groups was statistically significant. Moreover, we found high serum vitamin D level to be associated with t allelic frequency.

Conclusions

Unexpectedly, the mean serum vitamin D level of the test group was significantly higher than that of the control group. Tru9I polymorphism was found to be significantly correlated with the prevalence of medullary thyroid carcinoma.

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.

Single-Nucleotide Polymorphisms in Vitamin D-Related Genes May Modify Vitamin D-Breast Cancer Associations

Background: We previously observed that high serum 25-hydroxyvitamin D (25(OH)D; >38.0 ng/mL) was inversely associated with breast cancer. Here, we examined effect modification by SNPs in vitamin D-related genes.Methods: The Sister Study enrolled 50,884 U.S. women who had a sister with breast cancer, but who had never had breast cancer themselves. Using a case-cohort design, we compared 1,524 women who developed breast cancer within 5 years to 1,810 randomly selected participants. We estimated ratios of HRs (RHRs) for the 25(OH)D-breast cancer association per copy of the minor allele using Cox proportional hazards models. We considered 82 SNPs in 7 vitamin D-related genes (CYP24A1, CYP27B1, CYP2R1, GC, DHCR7/NADSYN1, RXRA, and VDR). We also tested gene-based interactions with 25(OH)D.Results: The SNP with the smallest interaction P value was rs4328262 in VDR (P = 0.0008); the 25(OH)D HR was 0.92 [95% confidence interval (CI), 0.68-1.24] among those homozygous for the common allele, and the minor allele was estimated to decrease the HR by 33% per copy (RHR = 0.67; 95% CI, 0.53-0.85). Five other VDR SNPs showed evidence of interaction at P < 0.05, as did one SNP in CYP2R1 and one in RXRA As a group, the 82 SNPs showed evidence of multiplicative interaction with 25(OH)D (P = 0.04). In gene-based tests, only VDR showed strong evidence of interaction (P = 0.04).Conclusions: SNPs in vitamin D-related genes may modify the association between serum 25(OH)D and breast cancer.Impact: This work strengthens the evidence for protective effects of vitamin D. Cancer Epidemiol Biomarkers Prev; 26(12); 1761-71. ©2017 AACR.

Vitamin D receptor polymorphisms or serum levels as key drivers of breast cancer development? The question of the vitamin D pathway

As total vitamin D levels are often lower in black than in white Americans, the former are frequently classified as vitamin D-deficient. To fully understand African vitamin D (25(OH)D) status, other factors should be considered, e.g. vitamin D blood carrier, vitamin D-binding protein (DBP), vitamin D receptor (VDR) and DBP polymorphisms. A prospective study on an indigenous black Tanzanian and a Caucasian Italian population was performed on 50 healthy donors from both populations and 35 Caucasian and 18 African breast cancer patients. 25(OH)D and DBP serum levels were analyzed by ELISA. A1012G, Cdx2 and Fok1 VDR polymorphisms and DBP polymorphisms rs4588 and rs7041 were genotyped by real-time PCR. Vitamin D and DBP levels were lower in healthy African donors than in Caucasians. Africans had a significantly higher frequency of AA and CC for Cdx2 and Fok1 polymorphisms, respectively. These allelic variants were related to a higher transcription of VDR gene and a higher activity of VDR receptor. With regard to polymorphism distribution, Africans showed innate higher levels and activity of VDR. We conclude that a strengthening of the vitamin D pathway could have a protective role against the development of breast cancer in the African population.

Vitamin D Receptor Polymorphism and Breast Cancer Risk: A Meta-Analysis

The objective was to perform a meta-analysis to summarize the available evidence from prospective nested case-control studies on the association of vitamin D receptor (VDR) polymorphism and the risk of breast cancer.We searched PubMed, ISI web of science, EMBASE, and reference lists for included articles. Study specific odds ratios (ORs) and 95% confidence intervals (CIs) were pooled by using fixed-effect or random-effects models.Eight studies were included in the meta-analysis. There were no association between Fok1 gene allele contrast f versus F (OR: 0.859; 95%CI: 0.685-1.079), ff versus FF (OR: 0.893; 95%CI: 0.763-1.045), recessive models ff versus FF+Ff (OR: 0.932; 95%CI: 0.796-1.092), and dominant models ff+Ff versus FF (OR: 0.899; 95%CI: 0.780-1.037). The estimated VDR polymorphism showed no significant association between Bsm1, Taq1, Apa1 polymorphism, and breast cancer risk. In the Caucasian ethnic subgroup, no association was found between allele contrast, recessive models, and dominant models on Fok1, Bsm1 polymorphism, and breast cancer risk.VDR polymorphism (Fok1, Bsm1, Taq1, and Apa1) were not associated with the risk of breast cancer in the general population as well as Caucasian population.

Vitamin D, Cancer Risk, and Mortality

Antiproliferative effects of 1,25-dihydroxyvitamin D, the biologically active form of vitamin D, are well established in various cell types by influencing cell differentiation and decreasing cell proliferation, growth, invasion, angiogenesis, and metastasis. Several meta-analyses showed that low serum levels of 25(OH)D was associated with colorectal cancer and overall mortality, while the association with cancer mortality was less consistent. VDR is a crucial mediator for the cellular effects of vitamin D and conflicting data have been reported for most malignancies. Beyond VDR, the biological effects of vitamin D are mediated by the vitamin D-binding protein. The GC (group-specific component) gene, encoding DBP, is highly polymorphic and several polymorphisms were investigated in association with cancer development with controversial results. Vitamin D supplementation was found to be associated with a reduced risk of overall mortality, reviewing all published trials on healthy subjects, whereas the evidence of an effect on cancer risk and mortality is less clear. Furthermore, long-term health effects of high doses of vitamin D, extended duration of supplementation, and the association with different baseline vitamin D levels remain to be investigated. In summary, epidemiological and preclinical studies support the development of vitamin D as preventative and therapeutic anticancer agents, with significant associations especially found for low vitamin D status with overall mortality and cancer outcome, more than cancer incidence. However, a definitive conclusion cannot be drawn and only large randomized clinical trials, both in healthy subjects and in cancer patients, will allow to draw definitive conclusions on the effect of vitamin D supplementation on cancer risk, prognosis, and mortality.

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.

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.

Vitamin D receptor polymorphism FokI and cancer risk: a comprehensive meta-analysis

Numerous studies investigated the associations of VDR polymorphisms with various types of cancer, suggesting an influence on cancer risk. FokI is one of the most frequently analysed polymorphisms but the results from single studies are contradictory. We performed a meta-analysis looking at the association between the FokI and all cancer sites and investigating sources of heterogeneity. We identified 77 independent studies up to April 2014. We presented the summary odds ratios (SORs) by cancer sites, ethnicity and study features. We found a significant association between FokI and ovarian cancer for ff genotype versus FF with no heterogeneity: SOR = 1.20 (95% CI: 1.02-1.41, I (2) = 0%). Moreover, we found a significant increased risk of any cancer: SOR = 1.08 (95% CI: 1.01-1.16, I (2) = 58%). A significant increased risk of any cancer is confirmed among Caucasian, among studies in Hardy-Weinberg equilibrium and nested case-control studies. Furthermore, among studies in Hardy-Weinberg equilibrium, skin cancer was found significantly associated with FokI: SOR = 1.24 (95% CI: 1.01-1.54; I (2) = 24%) for ff versus FF. The estimated number of cases attributable to ff genotype is 4221 for ovarian cancer and 52858 for skin cancer worldwide each year. No indication for publication bias was found for any cancer site. In conclusion, we found an overall significant association of FokI polymorphism with any cancer, with differential effect by ethnicity. In particular, the summary estimates indicate an increase risk for ovarian and skin cancer for ff versus FF. However, other factors may act modifying the association, and further studies are needed to clarify the impact on 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.

TaqI polymorphism of VDR gene contributes to breast cancer risk

Previous studies on the association of Vitamin D receptor (VDR) TaqI gene polymorphism with breast carcinogenesis have yielded inconsistent and inconclusive findings. The current meta-analysis was performed to provide a more precise assessment on the role of VDR TaqI polymorphism in breast cancer risk. 20 eligible case-control studies involving 9,055 cases and 10,516 controls were identified after a comprehensive literature search of the PubMed, Embase, Web of Science, and Wanfang databases. The pooled odds ratio (OR) with corresponding 95% confidence interval (95% CI) was calculated. Stratified analyses by ethnicity and study quality were conducted for further estimation. All statistical analyses were conducted by use of STATA (STATA Corporation, College Station, TX, Version 11.0). The overall ORs showed that the variant t allele and tt genotype were related to an increased risk of breast cancer (OR(t vs. T) = 1.05, 95% CI 1.01-1.10, P(OR) = 0.025; OR(tt vs. TT) = 1.12, 95% CI 1.03-1.23, P(OR) = 0.011; OR(tt vs. Tt + TT) = 1.10, 95% CI 1.01-1.20, P(OR) = 0.023). Stratified analyses of studies in Caucasians and with high-quality further confirmed the results. However, no significant relationship was observed among Asians. This meta-analysis suggests that the VDR TaqI polymorphism confers risk effect on the breast cancer development, particularly in Caucasians.

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 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.

Genetic analysis of the vitamin D receptor gene in two epithelial cancers: melanoma and breast cancer case-control studies

Background

Vitamin D serum levels have been found to be related to sun exposure and diet, together with cell differentiation, growth control and consequently, cancer risk. Vitamin D receptor (VDR) genotypes may influence cancer risk; however, no epidemiological studies in sporadic breast cancer (BC) or malignant melanoma (MM) have been performed in a southern European population. In this study, the VDR gene has been evaluated in two epithelial cancers BC and MM.

Methods

We have conducted an analysis in 549 consecutive and non-related sporadic BC cases and 556 controls, all from the Spanish population, and 283 MM cases and 245 controls. Genotyping analyses were carried out on four putatively functional SNPs within the VDR gene.

Results

An association with the minor allele A of the non-synonymous SNP rs2228570 (rs10735810, FokI, Met1Thr) was observed for BC, with an estimated odds ratio (OR) of 1.26 (95% CI = 1.02–1.57; p = 0.036). The synonymous variant rs731236 (TaqI) appeared to be associated with protection from BC (OR = 0.80, 95%CI = 0.64–0.99; p = 0.047). No statistically significant associations with MM were observed for any SNP. Nevertheless, sub-group analyses revealed an association between rs2228570 (FokI) and absence of childhood sunburns (OR = 0.65, p = 0.003), between the 3'utr SNP rs739837 (BglI) and fair skin (OR = 1.31, p = 0.048), and between the promoter SNP rs4516035 and the more aggressive tumour location in head-neck and trunk (OR = 1.54, p = 0.020).

Conclusion

In summary, we observed associations between SNPs in the VDR gene and BC risk, and a comprehensive analysis using clinical and tumour characteristics as outcome variables has revealed potential associations with MM. These associations required confirmation in independent studies.