Prostate cancer susceptibility is mediated by interactions between exposure to ultraviolet radiation and polymorphisms in the 5' haplotype block of the vitamin D receptor gene

The Association of a Novel Identified VDR SNP With Prostate Cancer in African American Men

BACKGROUND/AIM

Vitamin D receptor (VDR) is present in numerous cellular pathways and it has been suggested that VDR genetic variants influence individual susceptibility to prostate cancer. Also, analyses of single nucleotide polymorphisms (SNPs) in VDR revealed ethnicity-associated polymorphisms. The aim of this study was to identify VDR SNPs in African American men with and without prostate cancer.

MATERIALS AND METHODS

The entire VDR gene was screened for germline mutations in a case-control study by denaturing high performance liquid chromatography and DNA sequencing. Logistic regression was used to estimate the association of SNPs, age, family history, and Gleason score with prostate cancer risk.

RESULTS

Six SNPs in the non-coding regions, and one SNP in the coding region, were detected. SNP 1 (c.278-69G>A) and SNP 4 (c.907+75C>T) have not been previously reported. SNP 4 had a significant protective effect (β=-0.6, p<0.05); whereas, SNP 7 (rs7975232) showed an increase association with prostate cancer risk and high Gleason score (β=0.32, p<0.05). SNP 4, SNP 7 and age were better predictors of prostate cancer risk than family history with a high degree of sensitivity (74.7%) and specificity (92.4%).

CONCLUSION

SNP 4 and SNP 7 could be promising markers for prediction of reduced or increased prostate cancer risk, respectively.

Association of Vitamin D receptor Fok I polymorphism with the risk of prostate cancer: a meta-analysis

Several previous studies have been reported to examine the association between Vitamin D receptor (VDR) gene Fok I polymorphism and susceptibility to prostate cancer (PCa), however the results remain inconclusive. To provide a relatively comprehensive account of the association, we searched PubMed, Embase, CNKI, and Wanfang for eligible studies and carry out this meta-analysis. A total of 27 case-control studies with 10,486 cases and 10,400 controls were included. In the overall analysis, Fok I polymorphism was not significantly associated with the susceptibility to PCa. Subgroup analyses showed that significantly association was existed in Caucasian population, the subgroup of population-based controls and the stratified group with advanced tumor.These results indicate that the VDR Fok I polymorphism might be capable of causing PCa susceptibility and could be a promising target to forecast the PCa risk for clinical practice. However further well-designed epidemiologic studies are needed to confirm this conclusion.

Updated analysis of vitamin D receptor gene FokI polymorphism and prostate cancer susceptibility

INTRODUCTION

Polymorphisms of the vitamin D receptor (VDR) gene have been investigated in various case-control studies to evaluate prostate cancer susceptibility; however, published data on the association between vitamin D receptor gene FokI polymorphism and prostate cancer risk are inconclusive.

MATERIAL AND METHODS

To assess the impact of vitamin D receptor gene FokI polymorphism, we performed a meta-analysis of eligible studies including 9,720 patients and 9,710 control subjects.

RESULTS

The overall results indicated no obvious association of this variant on prostate cancer risk. However, in subgroup analysis by ethnicity, positive associations existed in Caucasian descendents for allelic contrast (OR = 1.03, 95% CI: 1.00-1.06, p_{heterogeneity} = 0.552, p = 0.026) and the dominant genetic model (OR = 1.03, 95% CI: 1.00-1.05, p_{heterogeneity} = 0.856, p = 0.032). In the subgroup analysis by tumor stage, there was a significant association between this variant and advanced prostate cancer under the recessive genetic model (OR = 1.15, 95% CI: 1.01-1.32, p_{heterogeneity} = 0.469, p = 0.032). In the subgroup analysis by source of control, association of the VDR FokI polymorphism and prostate cancer susceptibility was also found in population-based studies under homozygote comparison and the recessive genetic model.

CONCLUSIONS

The VDR FokI polymorphism may contribute to the risk of developing prostate cancer in Caucasian and population-based studies. Further large, well-designed studies are warranted to confirm this conclusion in more detail.

Meta-analysis of vitamin D-binding protein and cancer risk

BACKGROUND

Epidemiologic evidence supported a role for vitamin D and vitamin D receptor (VDR) polymorphisms in cancer risk. Beyond VDR, the biologic effects of vitamin D are mediated by the vitamin D-binding protein (DBP), a key protein in vitamin D metabolism. Furthermore, the gene encoding the DBP (GC, group-specific component) has an important role in the vitamin D pathway. Several studies investigated DBP serologic levels and GC polymorphisms in association with cancer risk with controversial results. Thus, we carried out a meta-analysis to investigate these associations.

METHODS

We included 28 independent studies concerning the following tumors: basal cell carcinoma, bladder, breast, colon-rectum, endometrium, liver, esophagus, stomach, melanoma, pancreas, prostate, and kidney. Through random-effect models, we calculated the summary odds ratios (SOR) for serum DBP and the GC polymorphisms rs2282679, rs12512631, rs7041, rs4588, rs17467825, rs1155563, and rs1352844.

RESULTS

We found a borderline decrease in cancer risk for subjects with high compared with low levels of DBP [SOR, 0.75; 95% confidence interval (CI), 0.56-1.00]. Dose-response meta-analysis indicates a nonsignificant decrease risk for an increase of 1,000 nmol/L of DBP (SOR, 0.96; 95% CI, 0.91-1.01). We found no significant alterations in cancer risk for subjects carrying any of the studied GC polymorphisms compared with wild-type subjects both in the main analysis and in analyses stratified by cancer type and ethnicity.

CONCLUSIONS

We found trends toward significance, suggesting a role of DBP in cancer etiology, which should be confirmed in further studies.

IMPACT

To our knowledge, this is the first study to investigate GC polymorphisms and DBP serologic levels in association with any type of cancer.

Does maternal VDR FokI single nucleotide polymorphism have an effect on lead levels of placenta, maternal and cord bloods?

INTRODUCTION

Individual susceptibility due to genetic variations appears to be an important factor in lead toxicity. As lead, ubiquitous atmospheric pollutant, behaves very similarly to calcium, gene polymorphisms in proteins involved in calcium homeostasis can affect lead toxicokinetics. Vitamin D receptor (VDR), a DNA-binding transcription factor, activates genes that encode proteins involved in calcium metabolism. Thus, the objective of this study was to determine the effect of maternal VDR FokI polymorphism on lead levels of maternal blood, placental tissue and cord blood.

METHODS

The study population comprised 116 women and their respective placenta and umbilical cord. Venous blood samples were drawn from mothers to investigate both the lead levels and VDR FokI polymorphism. Cord blood samples and placentas were collected for lead levels. VDR FokI polymorphism was detected by standard polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method. Lead levels were analyzed by dual atomic absorption spectrometer system.

RESULTS

Genotype frequencies of VDR FokI polymorphism were 49.2% FF, 44.8% Ff and 6.0% ff. The mean lead levels of maternal blood, placenta and cord blood were 36.76 ± 13.84 μg/L, 12.84 ± 14.47 μg/kg and 25.69 ± 11.12 μg/L, respectively. Maternal blood, placental and cord blood lead levels were found significantly to be higher in mothers with f allele for the VDR FokI polymorphism (p < 0.05).

DISCUSSION

The present study indicated that this polymorphism had an effect on maternal and fetal lead levels and that mothers with F allele associated with lower lead concentration may protect their respective fetus against the toxic effects of lead exposure.

Evidence of differential effects of vitamin d receptor variants on epithelial ovarian cancer risk by predicted vitamin d status

INTRODUCTION

Experimental studies suggest vitamin D inhibits ovarian carcinogenesis. Yet, epidemiologic studies of ovarian cancer risk and lifestyle correlates of vitamin D status, plasma 25-hydroxyvitamin D [25(OH)D], or vitamin D receptor (VDR) variants have been inconsistent.

OBJECTIVE

To evaluate VDR genetic associations by high vs. low predicted 25(OH)D, scores derived from known determinants of plasma 25(OH)D. To assess ovarian cancer associations with variants identified in genome-wide association studies (GWAS) of plasma 25(OH)D.

METHODS

We genotyped up to seven VDR and eight 25(OH)D GWAS variants in the Nurses' Health Studies (562 cases, 1,553 controls) and New England Case-Control study (1,821 cases, 1,870 controls). We estimated haplotype scores using expectation-maximization-based algorithms. We used unconditional logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CI). We combined study results using DerSimonian and Laird meta-analysis.

RESULTS

Ovarian cancer risk increased per A allele of rs7975232 (VDR; OR = 1.12, 95% CI = 1.01-1.25) among all women. When stratified by predicted 25(OH)D, ovarian cancer was associated with rs731236 (VDR; per C allele OR = 1.31) and rs7975232 (OR = 1.38) among women with high predicted 25(OH)D, but not among women with low levels (P ≤ 0.009). We also observed heterogeneity by predicted 25(OH)D for the ovarian cancer association with VDR 3' end haplotypes (P = 0.009). Of 25(OH)D-associated GWAS loci, rs7041 was associated with reduced ovarian cancer risk (per T allele OR = 0.92, 95% CI = 0.85-0.99), which did not differ by predicted 25(OH)D status.

CONCLUSION

Our study suggests an influence of VDR 3' end variants on ovarian cancer risk may be observed in women with high predicted 25(OH)D, which remained even after taking multiple comparisons into consideration. Future studies are needed to confirm our results and explore further the relation between vitamin D exposure, genetic variants, and ovarian 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.

Polymorphisms in the vitamin D Receptor (VDR) and the risk of ovarian cancer: a meta-analysis

The vitamin D receptor (VDR) principally mediates the anticancer activities of vitamin D. Various epidemiological studies have investigated the associations of VDR gene polymorphisms with ovarian cancer; however, the results have been inconclusive. In the current study, we evaluated, in a meta-analysis, the association of five common single nucleotide polymorphisms (SNPs) in the VDR gene (ApaI, BsmI, Cdx-2, FokI, and TaqI) with the risk of ovarian cancer. Six eligible studies, with a total of 4,107 cases and 6,661 controls, which evaluated the association of these variants and ovarian cancer risk, were identified from the MEDLINE and PubMed databases. The meta-analysis indicated that FokI was associated with an increased ovarian cancer risk, with a pooled odds ratio (OR) of 1.10 [95% confidence intervals (95% CI) = 1.00-1.20] for CT heterozygotes and 1.16 (95% CI = 1.02-1.30) for TT homozygotes relative to common CC carriers. Carriers of the T allele (also known as the f allele) showed an 11% (pooled OR = 1.11, 95% CI = 1.02-1.21; TT/CT vs. CC) increased risk of ovarian cancer relative to CC carriers. For FokI, no significant heterogeneity between the studies was found (I(2) = 0%, P = 0.62 for the Q test). There was no statistically significant association between the other four variants (ApaI, BsmI, Cdx-2 and TaqI) and risk of ovarian cancer. These data indicate that the polymorphism FokI on the VDR is a susceptibility factor for ovarian cancer. Nevertheless, more studies are warranted to elucidate the underlying mechanisms of the VDR in development of ovarian cancer.

Effect of interval between serum draw and follow-up period on relative risk of cancer incidence with respect to 25-hydroxyvitamin D level: Implications for meta-analyses and setting vitamin D guidelines

Ecological studies have reported strong inverse correlations between indices of solar ultraviolet-B (UVB) doses and incidence and/or mortality rates for many types of cancer. Case-control studies (CCS) generally find inverse correlations between serum 25-hydroxyvitamin D [25(OH)D] concentration measured at time of diagnosis for cancer incidence, whereas nested case-control studies (NCCS), which involve a several-year follow-up time after serum sampling, generally do not. This paper examines the relation between follow-up interval and relative risk (RR) for breast, colorectal, and prostate cancer. I plot the RR versus serum 25(OH)D data as a function of follow-up time from the literature for each type of cancer. For breast cancer, RRs were significantly reduced only for follow-up periods less than 3 years. For colorectal cancer, RRs were generally significantly reduced for follow-up periods up to 12 years. For prostate cancer, RRs were not statistically significant from 4 years to 28 years. This study included no CCS. Follow-up periods after serum sampling should not be too long for breast cancer because once a tumor reaches a diameter of 1-3 mm, it requires angiogenesis to continue growing, and vitamin D reduces angiogenesis around tumors. Breast cancer diagnoses are more common in spring and fall than in summer or winter, indicating that they can grow rapidly if circulating 25(OH)D drops in the fall or melatonin levels drop in spring. Serum sampling should be conducted during the study, perhaps every 2 years, to overcome the problem of change of 25(OH)D concentration during cohort studies.

Vitamin d, sunlight and prostate cancer risk

Prostate cancer is the second common cancer in men worldwide. The prevention of prostate cancer remains a challenge to researchers and clinicians. Here, we review the relationship of vitamin D and sunlight to prostate cancer risk. Ultraviolet radiation of the sunlight is the main stimulator for vitamin D production in humans. Vitamin D's antiprostate cancer activities may be involved in the actions through the pathways mediated by vitamin D metabolites, vitamin D metabolizing enzymes, vitamin D receptor (VDR), and VDR-regulated genes. Although laboratory studies including the use of animal models have shown that vitamin D has antiprostate cancer properties, whether it can effectively prevent the development and/or progression of prostate cancer in humans remains to be inconclusive and an intensively studied subject. This review will provide up-to-date information regarding the recent outcomes of laboratory and epidemiology studies on the effects of vitamin D on prostate cancer prevention.

Vitamin D pathway gene variants and prostate cancer prognosis

BACKGROUND

Observational studies linking vitamin D deficiency with increased prostate cancer (PCa) mortality and the pleiotropic anticancer effects of vitamin D in malignant prostate cell lines have initiated trials examining potential therapeutic benefits of vitamin D metabolites. There have been some successes but efforts have been hindered by risk of inducing hypercalcemia. A limited number of studies have investigated associations between variants in vitamin D pathway genes with aggressive forms of PCa. Increased understanding of relevant germline genetic variation with disease outcome could aid in the development of vitamin-D-based therapies.

METHODS

We undertook a comprehensive analysis of 48 tagging single-nucleotide polymorphisms (tagSNPs) in genes encoding for vitamin D receptor (VDR), vitamin D activating enzyme 1-alpha-hydroxylase (CYP27B1), and deactivating enzyme 24-hydroxylase (CYP24A1) in a cohort of 1,294 Caucasian cases with an average of 8 years of follow-up. Disease recurrence/progression and PCa-specific mortality risks were estimated using adjusted Cox proportional hazards regression.

RESULTS

There were 139 cases with recurrence/progression events and 57 cases who died of PCa. Significantly altered risks of recurrence/progression were observed in relation to genotype for two VDR tagSNPs (rs6823 and rs2071358) and two CYP24A1 tagSNPs (rs927650 and rs2762939). Three VDR tagSNPs (rs3782905, rs7299460, and rs11168314), one CYP27B1 tagSNP (rs3782130), and five CYP24A1 tagSNPs (rs3787557, rs4809960, rs2296241, rs2585428, and rs6022999) significantly altered risks of PCa death.

CONCLUSIONS

Genetic variations in vitamin D pathway genes were found to alter both risk of recurrence/progression and PCa-specific mortality.

Vitamin d pathway genes, diet, and risk of renal cell carcinoma

Mediated by binding to the high-affinity vitamin D receptor (VDR), vitamin D forms a heterodimer complex with the retinoid-X-receptor (RXR). Variation in both genes has been shown to modify renal cell carcinoma (RCC) risk. Therefore, we investigated whether VDR and RXRA polymorphisms modify associations between RCC risk and frequency of dietary intake of vitamin D and calcium rich foods, and occupational ultraviolet exposure among 777 RCC case and 1035 controls from Central and Eastern Europe. A positive association was observed in this population between increasing dietary intake frequency of yogurt, while an inverse association was observed with egg intake frequency. RXRA polymorphisms, located 3' of the coding sequence, modified associations between specific vitamin D rich foods and RCC risk, while RXRA polymorphisms, located in introns 1 and 4, modified associations with specific calcium rich foods. Results suggest that variants in the RXRA gene modified the associations observed between RCC risk and calcium and vitamin D intake.

Review and meta-analysis on vitamin D receptor polymorphisms and cancer risk

It was suggested that vitamin D levels influence cancer development. The vitamin D receptor (VDR) is a crucial mediator for the cellular effects of vitamin D. Results from previous studies on the association of VDR polymorphisms with different cancer types are somewhat contradictory, and the role of VDR in the etiology of cancer is still equivocal. We therefore performed a meta-analysis on the association between the two most studied VDR polymorphisms (FokI and BsmI) and any cancer site. Up to January 2009, we identified 67 independent studies. We used random-effects models to provide summary odds ratio (SOR) for VDR polymorphisms and cancer. We tested homogeneity of effects across studies and publication bias and explored between-study heterogeneity. When comparing FokI ff with FF carriers, we found a significant increase in skin cancer [SOR; 95% confidence intervals (CIs): 1.30; 1.04-1.61] and breast cancer (SOR; 95%CI: 1.14; 1.03-1.27) risk. For the same genotype comparison, we found a significantly higher risk of cancer when we pooled estimates from cancer sites possibly associated with vitamin D levels (prostate, breast, skin, ovary, non-Hodgkin lymphoma and colorectal). A significant reduction in prostate cancer risk was observed for carriers of BsmI Bb compared with bb genotype (SOR; 95%CI: 0.83; 0.69-0.99). In Caucasian populations, both Bb and BB carriers had a significant reduced risk of cancer at any site. In conclusion, this meta-analysis showed that VDR FokI and BsmI polymorphisms might modulate the risk of cancer of breast, skin and prostate and possibly affect cancer risk at any site in Caucasians.

Past environmental sun exposure and risk of multiple sclerosis: a role for the Cdx-2 Vitamin D receptor variant in this interaction

Multiple studies have provided evidence for an association between reduced sun exposure and increased risk of multiple sclerosis (MS), an association likely to be mediated, at least in part, by the vitamin D hormonal pathway. Herein, we examine whether the vitamin D receptor ( VDR), an integral component of this pathway, influences MS risk in a population-based sample where winter sun exposure in early childhood has been found to be an important determinant of MS risk. Three polymorphisms within the VDR gene were genotyped in 136 MS cases and 235 controls, and associations with MS and past sun exposure were examined by logistic regression. No significant univariate associations between the polymorphisms, rs11574010 ( Cdx-2A > G), rs10735810 ( Fok1T >  C), or rs731236 ( Taq1C > T) and MS risk were observed. However, a significant interaction was observed between winter sun exposure during childhood, genotype at rs11574010, and MS risk ( P = 0.012), with the ‘G’ allele conferring an increased risk of MS in the low sun exposure group (≤2 h/day). No significant interactions were observed for either rs10735810 or rs731236, after stratification by sun exposure. These data provide support for the involvement of the VDR gene in determining MS risk, an interaction likely to be dependent on past sun exposure.

Prostate cancer prevention by short-term anti-androgens: the rationale behind design of pilot studies

This paper sets out to review evidence that low-grade prostate inflammation is a precursor of prostate cancer development and the mechanisms by which it may account for the more than 50 years natural history from first infection to cancer. Though as yet there is no clear-cut specific associated infection, there is clear evidence that some sexually acquired infections damage the prostate and increase serum PSA with slow recovery back to normal. The demonstration that low-level solar exposure is protective provides a possible mechanism due to vitamin D's known benefit through action to boost macrophage-mediated immune surveillance. This observation and data demonstrating that non-steroidal anti-inflammatory drugs (NSAIDs) protect against prostate cancer provide the justification for trials of these two agents combined with short course intermittent anti-androgen therapy in populations at high risk of prostate cancer.

Variation in associations between allelic variants of the vitamin D receptor gene and onset of type 1 diabetes mellitus by ambient winter ultraviolet radiation levels: a meta-regression analysis

Vitamin D receptor (VDR) gene polymorphisms may be associated with risk of developing type 1 diabetes mellitus (T1DM), but reports have been conflicting. The authors reexamined population-based case-control studies on selected VDR polymorphisms and T1DM to investigate whether variation in reported associations could be partly explained by differences in ambient winter ultraviolet radiation (UVR) levels. A meta-analysis of 16 studies from 19 regions (midwinter UVR range, 1.0-133.8 mW/m(2)) was conducted. The association between winter UVR and the log odds ratio was examined by meta-regression. For FokI and BsmI, the log odds ratio for the association between the F and B alleles and T1DM increased as regional winter UVR increased (p = 0.039 and p = 0.036, respectively). The association between the TaqI T allele and T1DM was reduced with increasing winter UVR (p = 0.040). Low winter regional UVR was associated with a higher proportion of controls carrying BsmI and ApaI uppercase alleles and a lower proportion of controls carrying TaqI uppercase alleles. These findings strengthen the case that VDR variants are involved in the etiology of T1DM. They suggest that environmental UVR may influence the association between VDR genotype and T1DM risk. Further work on VDR polymorphisms and T1DM should concomitantly examine the roles of past UVR exposure and vitamin D status.

Vitamin D and cancer: current dilemmas and future research needs

A diversity of scientific literature supports a role for vitamin D in decreasing colorectal cancer incidence, but the available evidence provides only limited support for an inverse association between vitamin D status and the risk of other types of cancer. We need additional studies analyzing the dose-response relation between vitamin D status and cancer risk, the optimal level of 25-hydroxyvitamin D, the length of time required to observe an effect, and the time period of life when exposure is most relevant. Studies of vitamin D receptor polymorphisms have found that not all polymorphisms have the same association with cancer, and the cancer site could further dictate which polymorphisms might be most important; this indicates a need for more research on gene-environment interactions. Several dietary components and the balance between energy intake and expenditure influence vitamin D metabolism. These studies show that scientists need to identify confounders and modifiers of the biological response to vitamin D, including dietary factors, lifestyle factors such as exercise, and race or ethnicity. Transgenic and knockout animals are powerful tools for identifying the molecular targets of bioactive food components. Scientists should therefore make increased use of these models to identify molecular targets for vitamin D. Many research gaps relate to the need to develop predictive, validated, and sensitive biomarkers, including biomarkers that researchers can use to reliably evaluate intake or exposure to vitamin D, assess one or more specific biological effects that are linked to cancer, and effectively predict individual susceptibility as a function of nutrient-nutrient interactions and genetics.

Vitamin D receptor gene polymorphism is associated with reduced disability in multiple sclerosis

Ultraviolet radiation (UVR) may contribute to multiple sclerosis (MS) outcome by a mechanism involving vitamin D and the vitamin D receptor (VDR). In 512 patients with MS duration of 10 or more years, we studied the association of VDR single nucleotide polymorphisms (A/G1229, C/G3444, G/A3944, CC20965, CC30056, F/f30875, C/T48200, T/t65013) with outcome or disability. ff30875 frequency was lower in cases with EDSS ≥ 6.0 than with scores < 6.0 (odds ratio = 0.38, 95% CI = 0.20–0.70). The association of ff30875 with outcome was not mediated by cumulative exposure to UVR as assessed by questionnaire; low exposure (odds ratio = 0.42, 95% CI = 0.14–1.34) and high exposure (odds ratio = 0.34, 95% CI = 0.16–0.73).

Vitamin D insufficiency among African-Americans in the southeastern United States: implications for cancer disparities (United States)

OBJECTIVE

To determine the prevalence and predictors of vitamin D insufficiency among black and white adult residents of the southern US.

METHODS

A cross-sectional analysis of serum 25(OH)D levels using baseline blood samples from 395 Southern Community Cohort Study (SCCS) participants. Participants were African-American and white adults aged 40-79 who enrolled in the study from 2002-2004. We defined hypovitaminosis D as serum 25(OH)D levels < or = 15 ng/ml.

RESULTS

Hypovitaminosis D prevalence was 45% among blacks and 11% among whites. Vitamin D intake from diet and supplements was associated with modest increases in circulating 25(OH)D (0.5-0.7 ng/ml per 100 IU increment), but hypovitaminosis D was found for 32% of blacks with intake > or = 400 IU/day. Body mass index (BMI) was a strong predictor of risk for hypovitaminosis D among black women (OR = 6.5, 95% CI 1.7-25.1 for BMI > or = 30 kg/m(2) vs. 18-24.9 kg/m(2)). UVR exposure estimated by residential location was positively associated with 25(OH)D levels among all groups except white women.

CONCLUSIONS

Hypovitaminosis D was present in a substantial proportion of the African-American population studied, even in the South and among those meeting recommended dietary guidelines. Vitamin D should continue to be a studied target for ameliorating racial cancer disparities in the US.

Vitamin D receptor (VDR) gene polymorphisms and haplotypes, interactions with plasma 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, and prostate cancer risk

BACKGROUND

The vitamin D receptor (VDR) is required for actions of vitamin D. The binding of 1,25-dihydroxyvitamin D to the VDR on prostatic epithelial cells prompts the regulation of cancer-related genes.

METHODS

We conducted a nested case-control study in the Health Professionals Follow-up Study to investigate the role of the VDR Cdx2, Fok1, and Bsm1 gene polymorphisms and associated haplotypes and their interaction with plasma vitamin D metabolites in relation to prostate cancer (PC) risk.

RESULTS

No association was found between these SNPs or their associated haplotypes and all PC subtypes except that haplotype 2 (A-f-b) with Cdx2 A, Fok1 f, and Bsm1 b alleles and haplotype 3 (A-F-B) with Cdx2 A, Fok1 F and Bsm1 B alleles compared to the most common haplotype (A-F-b), were associated with reduced risk of aggressive PC (high stage or Gleason sum > or =7; P = 0.02), both with two alleles suspected of being low risk. Carriers of the variant Cdx2 A allele who were deficient in plasma 25-hydroxyvitamin D (< or =15 ng/ml) compared to non-carriers with normal 25-hydroxyvitamin D, had a lower risk of total and poorly differentiated PCs (Gleason sum > or =7) (P for interaction = 0.02 and 0.04, respectively). Plasma 1,25-dihydroxyvitamin D deficiency (< or =26 pg/ml) was associated with a threefold risk of poorly differentiated PC (P for interaction = 0.01) when comparing carriers of the Cdx2 A allele to non-carriers with normal 1,25-dihydroxyvitamin D.

CONCLUSION

In this population of men, none of the VDR polymorphisms studied was associated with susceptibility to PC.