A novel polymorphism in the 1A promoter region of the vitamin D receptor is associated with altered susceptibilty and prognosis in malignant melanoma

Vitamin D, vitamin D receptor, and cathelicidin in the treatment of tuberculosis

Vitamin D plays a major role in bone mineral density and calcium homeostasis. Apart from its classical action, the active form of vitamin D [1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3))] influences the innate and adaptive immune functions through vitamin D receptor (VDR) that are present in various cells of the immune system. Vitamin D deficiencies have been associated with development of tuberculosis (TB) disease, caused by Mycobacterium tuberculosis. Vitamin D(3) is shown to enhance macrophage phagocytosis of M. tuberculosis and increases the production of antimicrobial peptide cathelicidin and killing of M. tuberculosis. During the preantibiotic era, exposure to sunlight and supplementation of vitamin D were the methods of choice for treatment of TB. Vitamin D supplementation showed sputum clearance and radiological improvement and reduction in mortality among human immunodeficiency virus (HIV)-infected patients with TB. VDR gene polymorphisms regulate the immunomodulatory effect of vitamin D(3) and are associated with faster sputum conversion during anti-TB treatment. The emerging evidences regarding immunomodulatory properties of vitamin D(3) have rekindled interest in vitamin D as an adjunct to anti-TB therapy. The current review explains the important potential application of vitamin D in enhancing the innate immunity to TB and the role of VDR gene variants on anti-TB treatment.

Growth, calcium status and vitamin D receptor (VDR) promoter genotype in European children with normal or low calcium intake

Calcium homeostasis and bone metabolism require the vitamin D receptor (VDR) to function properly, as evidenced in patients and transgenic mice with VDR mutations. We have shown that (A/G) polymorphism at the -1012 locus of the VDR promoter (rs4516035) is frequent in European populations, may influence VDR expression, is associated with height in French adolescent girls, and is associated with their lumbar spine mineral density in case of insufficient milk intake. Here, an association study was performed in a cohort of Moldovan children and adolescents, living at latitude similar to the first cohort but receiving a cereal-based diet with very low milk/dairy product intakes. Children and adolescents in this cohort had similar 25-(OH) D levels, but a short stature and low serum calcium levels, compared to the first cohort. Their height remained associated with the A-1012G VDRp genotype. In addition, their serum calcium levels were associated with VDRp polymorphism, excepted when their 25-(OH) D levels were low (below 33 nmol/L). In conclusion, the -1012 VDRp genotype appears to be associated with height in European children whatever their calcium/dairy product intakes, and may modulate their calcium homeostasis in conditions of low calcium/milk intakes when vitamin D status is sufficient.

Vitamin D receptor gene polymorphisms, serum 25-hydroxyvitamin D levels, and melanoma: UK case-control comparisons and a meta-analysis of published VDR data

We have carried out melanoma case-control comparisons for six vitamin D receptor (VDR) gene single nucleotide polymorphisms (SNPs) and serum 25-hydroxyvitamin D(3) levels in order to investigate the role of vitamin D in melanoma susceptibility. There was no significant evidence of an association between any VDR SNP and risk in 1028 population-ascertained cases and 402 controls from Leeds, UK. In a second Leeds case-control study (299 cases and 560 controls) the FokI T allele was associated with increased melanoma risk (odds ratio (OR) 1.42, 95% confidence interval (CI) 1.06-1.91, p=0.02). In a meta-analysis in conjunction with published data from other smaller data sets (total 3769 cases and 3636 controls), the FokI T allele was associated with increased melanoma risk (OR 1.19, 95% CI 1.05-1.35), and the BsmI A allele was associated with a reduced risk (OR 0.81, 95% CI 0.72-0.92), in each instance under a parsimonious dominant model. In the first Leeds case-control comparison cases were more likely to have a higher body mass index (BMI) than controls (p=0.007 for linear trend). There was no evidence of a case-control difference in serum 25-hydroxyvitamin D(3) levels. In 1043 incident cases from the first Leeds case-control study, a single estimation of serum 25-hydroxyvitamin D(3) level taken at recruitment was inversely correlated with Breslow thickness (p=0.03 for linear trend). These data provide evidence to support the view that vitamin D and VDR may have a small but potentially important role in melanoma susceptibility, and putatively a greater role in disease progression.

Why vitamin D for cancer patients?

Several epidemiological, pre-clinical and clinical studies support Vitamin D as a preventive and therapeutic cancer agent.

BACKGROUND

Vitamin D and cancer: calcitriol, the biologically active form of vitamin D (1,25(OH)D), exerts its effects mainly through binding to nuclear vitamin D receptor (VDR). Calcitriol has been shown to be an anti-proliferative, pro-differentiation, pro-apoptotic agent and an inhibitor of cell migration. Animal and human in vitro studies strongly indicate that vitamin D may have benefits for many forms of cancer. Inadequate levels of circulating 25-hydroxy-vitamin D (25(OH)D) are associated with an increased risk and poor prognosis of several types of cancer. Vitamin D and melanoma: cutaneous malignant melanoma (CMM) represents a major public health issue: rates in Italy have almost doubled in the last decade and CMM is frequent among young adults. For resected stage II melanoma no standard adjuvant treatment exists and five-year overall survival is about 70%. Cultured melanoma cells can synthesize calcitriol from 25(OH)D and express the VDR. Moreover, 1,25(OH)D has anti-proliferative and pro-differentiation effects in human melanoma cells. 1,25(OH)D has been shown to induce apoptosis in human melanoma cell lines and has an inhibitory effect on the spreading of melanoma cells in vitro. Preliminary results on vitamin D: epidemiological data indicate that vitamin D deficiency is relatively common in Europe. In an Italian study, we found that 85% of the participants had insufficient levels of 25(OH)D. We have shown through a meta-analysis of randomized trials that vitamin D supplementation is associated with a significant reduction (7%) in total mortality in healthy subjects and an association between VDR and 25(OH)D and CMM progression has also been demonstrated. We have also reported significant associations between VDR polymorphisms and incidence of skin cancer. In early supplementation trials, the lack of effect on cancer incidence has been attributed to insufficient vitamin D supplementation, stressing the need to better study vitamin D bioavailability. In fact, a recent IARC report highlighted the need for new randomized trials, based on results from our meta-analyses on 25(OH)D serum levels and cancer risk. Clinical trial and biomarkers studies: in order to assess whether vitamin D supplementation could improve prognosis of CMM, an Italian multi-centre trial in stage II resected melanoma patients was planned to monitor changes in 25(OH)D. The study will address two important questions regarding the relationship between the biology of VDR and (1) vitamin D metabolism, and (2) CMM prognosis. This will involve investigating the association between VDR polymorphisms and Breslow thickness, the most important prognostic factor of CMM, and between 25(OH)D serum level, vitamin D supplementation and VDR. We will also evaluate at baseline whether VDR polymorphisms are associated with Breslow thickness and whether we obtain significant increase in 25(OH)D serum levels during the first year of supplementation. We will quantify the percentages of patients who have desirable levels of 25(OH)D and, if they don't, the mean time to reach that level. The findings from this study will be of great interest because vitamin D could have anti-cancer benefits for a wide spectrum of cancers.

Cutaneous vitamin D synthesis versus skin cancer development: The Janus faces of solar UV-radiation

In scientific and public communities, there is an ongoing discussion how to balance between positive and negative effects of solar UV-exposure. On the one hand, solar UV-radiation represents the most important environmental risk factor for the development of non-melanoma skin cancer. Consequently, UV protection is an important measure to prevent these malignancies, especially in risk groups. Otherwise, approximately 90% of all vitamin D needed by the human body has to be formed in the skin through the action of UV-radiation. This dilemma represents a serious problem, for an association of vitamin D-deficiency and multiple independent diseases including various types of cancer, bone diseases, autoimmune diseases, infectious diseases, cardiovascular diseases and hypertension has now been reported in a large number of investigative and epidemiologic studies. As a consequence, it has been assumed that for the general population in the US, Europe and other countries, the net effects of solar UV B-radiation on human health are beneficial at or near current levels. We and others have shown that strict sun protection causes vitamin D-deficiency/insufficiency and that detection and treatment of vitamin D-deficiency in sun deprived risk groups is of high importance. Although further work is necessary to define an adequate vitamin D-status and adequate guidelines for solar and artificial UV-exposure, it is at present mandatory that public health campaigns and sun protection recommendations to prevent skin cancer consider these facts. In this review, we analyze the present literature to help developing well-balanced recommendations on sun protection that ensure an adequate vitamin D-status. These recommendations will hopefully protect us against adverse effects of UV protection without significantly increasing the risk to develop UV-induced skin cancer.

Management of familial melanoma and nonmelanoma skin cancer syndromes

The clinical manifestations of hereditary skin cancer syndromes depend upon the interplay between environmental and genetic factors. Familial melanoma occurs in the setting of hereditary susceptibility, with a complex phenotype of early age of onset, multiple atypical moles, multiple primary melanomas, multiple melanomas in the family, and in some instances pancreatic cancer. Identification of individuals who may have a hereditary susceptibility for the development of melanoma is essential to provide an opportunity for primary prevention, and to target high-risk groups for early diagnosis and treatment. Consequently, the surgeon as one of the primary caregivers should be familiar with hereditary skin cancer syndromes and their pathogenesis, diagnosis, management, and surveillance recommendations. This article discusses a practical approach for some of the issues likely encountered by the surgeon in the management of familial melanoma and non-melanoma skin cancer.

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.

Vitamin D receptor genotype in hypophosphatemic rickets as a predictor of growth and response to treatment

CONTEXT

Treatment of X-linked hypophosphatemic rickets improves bone mineralization and bone deformities, but its effect on skeletal growth is highly variable.

OBJECTIVE

Genetic variants in the promoter region of the vitamin D receptor (VDR) gene may explain the response to treatment because this receptor mediates vitamin D action.

DESIGN

We studied the VDR promoter haplotype structure in a large cohort of 91 patients with hypophosphatemic rickets including 62 patients receiving 1alpha-hydroxyvitamin D3 derivatives and phosphates from early childhood on.

RESULTS

Treatment improved bone deformities and final height, but 39% of treated patients still had short stature at the end of growth (-2 sd score or below). Height was closely associated with VDR promoter Hap1 genotype. Hap1(-) patients (35% of the cohort) had severe growth defects. This disadvantageous association of Hap1(-) status with height was visible before treatment, under treatment, and on to adulthood. Gender and age at initiation of treatment could not account for the Hap1 effect. No association with growth was found with a polymorphism of the PTH receptor gene otherwise found to be associated with adult height. Compared with Hap1(+) patients, those who were Hap1(-) had a higher urinary calcium response to 1alpha-hydroxyvitamin D3 and had significantly lower circulating FGF23 levels (C-terminal assay), taking into account their phosphate and 1alpha-hydroxyvitamin D3 intakes.

CONCLUSIONS

The present work identifies the VDR promoter genotype as a key predictor of growth under treatment with 1alpha-hydroxyvitamin D3 derivatives in patients with hypophosphatemic rickets, including those with established PHEX alterations. The VDR promoter genotype appears to provide valuable information for adjusting treatment and for deciding upon the utility of early GH therapy.

Vitamin D and skin cancer: a meta-analysis

A comprehensive bibliographic search of the literature was conducted to identify studies on Cutaneous Malignant Melanoma (CMM) and non-melanoma skin cancer (NMSC), Vitamin D receptor (VDR) polymorphisms, Vitamin D intake and 25(OH)D serum levels. Fully adjusted risk estimates were found and extracted for the two polymorphisms FokI and BsmI and Vitamin D intake. Ten studies were included in the meta-analysis, with a total of 6805 skin cancer cases. We found an association with CMM for both polymorphisms. The summary relative risks (SRR) for the studies on CMM were: 1.21 (1.03-1.42) and 1.21 (0.95-1.54) for the Ff and ff versus wild-type of FokI, respectively. The SRR for ff versus wild-type became significant with the inclusion of NMSC. The SRR for the studies on CMM were: 0.78 (0.65-0.92) and 0.75 (0.59-0.95) for the Bb and BB versus wild-type of BsmI, respectively. There is also a slight indication of a role of dietary Vitamin D in CMM development. In conclusion, this meta-analysis suggests a possible significant role of VDR FokI and BsmI polymorphism in CMM and NMSC risk. The association with Vitamin D intake is less clear and further studies could be useful to clarify the role of diet.

5' regulatory and 3' untranslated region polymorphisms of vitamin D receptor gene in south Indian HIV and HIV-TB patients

INTRODUCTION

Vitamin D receptor (VDR) gene polymorphisms in the 5' regulatory region (Cdx2 and A-1012G), coding region (FokI), and 3' untranslated region (UTR; BsmI, ApaI, and TaqI) were studied to find out whether these polymorphisms are associated with susceptibility to or protection against HIV-1 and development of tuberculosis (TB) in human immunodeficiency virus (HIV)-1-infected patients.

STUDY SUBJECTS AND METHODS

The study was carried out in 131 HIV patients without TB (HIV+ TB-) and 113 HIV patients with TB (HIV+ TB+; includes 82 patients with pulmonary TB (HIV+ PTB+) and 31 with extra pulmonary TB), 108 HIV-negative pulmonary TB patients (HIV- PTB+), and 146 healthy controls.

RESULTS

Among the 5' regulatory and coding region polymorphisms, significantly increased frequency of G/A genotype of Cdx-2 was observed in HIV+ TB- group compared to controls (p = 0.012, odds ratio (OR) 1.89 95% confidence interval (CI) 1.14-3.15). In the 3' UTR genotypes, a decreased frequency of b/b genotype of BsmI in total HIV patients (p = 0.014, OR 0.54 95% CI 0.32-0.89) and increased frequencies of A/A genotype of ApaI in HIV+ TB+ patients (p = 0.041, OR 1.77 95% CI 1.02-3.06) and t/t genotype of TaqI in HIV+ PTB+ patients (p = 0.05, OR 2.32 95% CI 0.99-5.46) were observed compared to controls. Haplotype analysis revealed significantly increased frequencies of 3' UTR haplotype B-A-t in HIV+ TB+ and HIV+ PTB+ groups (Pc = 0.030, OR 1.75 95% CI 1.14-2.66) and decreased frequencies of b-A-T haplotype in total HIV patients (Pc = 0.012, OR 0.46 95% CI 0.27-0.77), HIV+ TB- (p = 0.031 OR 0.48 95% CI 0.25-0.89), and HIV+ PTB+ groups (Pc = 0.04, OR 0.47 95% CI 0.23-0.89) compared to controls.

CONCLUSIONS

The results suggest that VDR gene 3' UTR haplotype b-A-T may be associated with protection against HIV infection while B-A-t haplotype might be associated with susceptibility to development of TB in HIV-1-infected patients.

Regulatory role of promoter and 3' UTR variants of vitamin D receptor gene on cytokine response in pulmonary tuberculosis

Vitamin D receptor (VDR) gene variants are shown to regulate immune response in tuberculosis. We studied the influence of VDR promoter (Cdx-2 and A1012G), 3' untranslated region (Apa I, Bsm I, and Taq I) and start codon (Fok I) polymorphisms on 1,25(OH)(2)D(3)-modulated IL-12p40, IFN-gamma, IL-10, and IL-5 response to live Mycobacterium tuberculosis and its culture filtrate antigen (CFA) in 60 normal healthy subjects and 51 pulmonary tuberculosis patients. In peripheral blood mononuclear cell cultures with CFA and 1,25(OH)(2)D(3), IL-12p40, and IFN-gamma levels were significantly decreased (p < 0.05) and IL-10 levels were significantly increased (p < 0.05) in patients with GG genotype. The extended genotype bbaaTT (baT haplotype) was associated with decreased IL-12p40 and IFN-gamma levels and significantly increased IL-10 levels (p < 0.05). The Cdx-2 GG genotype and baT haplotype are associated with a suppressed Th1 and increased IL-10 response, which suggests that 1,25(OH)(2)D(3) probably through the VDR polymorphic variants augments the anti-inflammatory response at the site of M. tuberculosis infection.

Melanocyte receptors: clinical implications and therapeutic relevance

The activation or the inhibition of melanocyte-specific receptors offers novel means of augmenting normal melanocyte function, skin color, and photoprotection, or treating melanocytic disorders, namely at this time, metastatic melanoma. Melanocyte-specific receptors include melanocortin-1 (MCR1) and melatonin receptors. Other receptors that play an important role in melanoma progression are G-protein couple receptors such as Frizzled 5 and receptor tyrosine kinases such as c-Kit and hepatocyte growth factor (HGF) receptor. These receptors activate two crucial cell-signaling pathways, RAS/RAF/MEK/ERK and PI3K/AKT, integral to melanoma cell survival, and can serve as targets for therapy of disseminated melanoma. Activation of death receptors is another pathway that can be exploited with targeted therapeutics to control advanced melanoma. This article reviews the current understanding of melanocyte receptors, their agonists and inhibitors, and their potential to treat the melanocytic pathology.

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.

Polymorphisms of vitamin D receptor and survival in early-stage non-small cell lung cancer patients

Our previous analysis suggested that surgery season in the summer time and high vitamin D intake are associated with improved survival in early-stage non-small cell lung cancer (NSCLC) patients. Here, we investigated the associations of vitamin D receptor (VDR) polymorphisms of Cdx-2 G>A, FokI C>T, and BsmI C>T with overall survival (OS) and recurrence-free survival (RFS) in 373 early-stage NSCLC patients. The data were analyzed using log-rank test and Cox proportional hazards models. The median follow-up time was 71 months (range, 0.1-140 months), with 186 deaths and 127 recurrences. There was no association between VDR polymorphisms and survival, overall or among adenocarcinoma patients. Among squamous cell carcinoma (SCC) patients, the G/A+A/A genotype group of the Cdx-2 polymorphism was associated with better OS: the 5-year OS rates were 41% [95% confidence interval (95% CI), 28-53] for the G/G and 55% (95% CI, 39-71) for the G/A+A/A genotypes, respectively (P = 0.04, log-rank test), with the adjusted hazard ratio of 0.56 (95% CI, 0.33-0.95) for G/A+A/A versus G/G. For the joint effects of the three polymorphisms, subjects with two or more "protective" alleles have better OS among SCC patients, with the adjusted hazard ratios of 0.20 (95% CI, 0.09-0.48), 0.40 (95% CI, 0.19-0.87), and 0.43 (95% CI, 0.19-0.97), respectively, for subjects with two, three, and four or more "protective" alleles when compared with subjects with zero or one "protective" allele (P(trend) = 0.71). Similar associations were found in haplotype analysis and for RFS among SCC patients. In conclusion, VDR polymorphisms may be associated with improved survival among SCC patients of early-stage NSCLC.

Molecular genetic analysis of NBS1 in German melanoma patients

The aim of this study was to investigate the role of NBS1 in the pathogenesis of malignant melanoma of the skin. To exclude the common 657del5 founder mutation, a total of 376 melanoma patients from Southern Germany were analyzed for sequence alterations in exon 6 of NBS1 by direct sequencing. Analyses revealed one 657del5 mutation and three nonsynonymous sequence variations in exon 6 of NBS1 (V210F, R215W, and F222L). Analysis of an additional sample of 629 melanoma patients and 604 controls revealed no F222L mutation, indicating that this newly identified sequence alteration is not a common polymorphism. In a case-control association study including 632 melanoma patients and 615 cancer-free control participants from Southern Germany, three publicly known single nucleotide polymorphisms located in the NBS1 gene region were analyzed. No significant associations between single nucleotide polymorphisms (rs9995, rs867185 and rs1063045) or referring calculated haplotypes and melanoma risk were identified. These results suggest that NBS1 does not play a major role in predisposition to melanoma in the Southern German population but that alterations of this gene might contribute to the risk of this cancer.

Exons and functional regions of the human vitamin D receptor gene around and within the main 1a promoter are well conserved among mammals

The human vitamin D receptor (hVDR) gene encompasses eight exons (2-9) in the so-called coding region and six more exons (1a-1f) in the so-called regulatory region, which contains several reported promoters. Evolutionary comparison performed on the VDR promoter sequences of a dozen of mammalian species shows a very high conservation of numerous regions around and in the 1a promoter, including exons 1e, 1a and 1d, and the Sp1 site region. This suggests that the so-called 1a promoter is well conserved among mammals. Homology among mammals also concerns three functional SNP site regions of the hVDR 1a promoter, the 1e-G-1739A SNP region (a Cdx-2 binding site), and both 1a-G-1521C and 1a-A-1012G sites, the 1a-1012A being located within a GATA site. Interestingly, the 1521G and 1012A nucleotides are being evolutionary conserved, suggesting that the 1521C/1012G haplotype, which is found in human chromosomes (43% of Caucasians), is a human specificity.

Genetic Variants of the Vitamin D Receptor Gene Alter Risk of Cutaneous Melanoma

Sunlight causes DNA damage but also induces production of vitamin D whose metabolite 1,25-(OH)2D3 has antiproliferative and pro-differentiative effects in both melanocytes and cutaneous melanoma (CM) cells mediated through the vitamin D receptor (VDR). We hypothesized that genetic polymorphisms of VDR are associated with risk of CM. In a hospital-based case-control study of 602 non-Hispanic white CM patients and 603 cancer-free control subjects frequency matched by age and sex, we genotyped two VDR polymorphisms (TaqI and FokI) and assessed their association with CM risk. We found that a significantly decreased risk was associated with VDR-TaqI Tt (adjusted odds ratio (OR), 0.70; 95% confidence interval (CI), 0.54-0.90) and Tt+tt (OR=0.70; 95% CI, 0.55-0.89) genotypes, compared with the VDR-TaqI TT genotype, whereas an increased risk was associated with VDR-FokI Ff genotype (OR=1.32; 95% CI, 1.03-1.68), and a borderline significantly increased risk was associated with Ff+ff (OR=1.26; 95% CI, 1.00-1.59) genotypes, compared with the VDR-FokI FF genotype. In conclusion, genetic variants (i.e., TaqI t protective allele and FokI f risk allele) in VDR may alter risk of CM.

Association between cutaneous melanoma, Breslow thickness and vitamin D receptor BsmI polymorphism

BACKGROUND

Literature data report an association between some vitamin D receptor (VDR) polymorphisms and different kinds of tumours, including malignant melanoma (MM). Only three VDR polymorphisms (FokI, TaqI and A-1012G) have been investigated in association with the presence of cutaneous MM or the development of metastases.

OBJECTIVES

The present paper analyses for the first time the association between BsmI polymorphism and MM prevalence together with Breslow thickness. In addition, the FokI single nucleotide polymorphism was also determined.

METHODS

One hundred and one patients with MM and 101 healthy donors matched for age and sex were enrolled. Molecular VDR typing was performed by means of restriction fragment length polymorphism analysis.

RESULTS

All cases and controls were in Hardy-Weinberg equilibrium for BsmI, FokI and A-1012G. Significant associations were found between the BsmI bb genotype frequency and MM (P = 0.02) along with Breslow thickness (P = 0.001). This same behaviour was not observed for the FokI or A-1012G polymorphisms. Multivariate logistic regression analysis confirmed these significant results after correction for age, gender, skin type and MM localization.

CONCLUSIONS

Although the biological meaning of the effects exerted by BsmI polymorphism is still under debate, the statistical association found in the present study suggests that further work should be done to verify this variant as a possible risk marker for MM and its aggressiveness, also considering that the real association may be due to other unknown genes linked to the BsmI b allele.

DNA repair gene polymorphisms and genetic predisposition to cutaneous melanoma

The incidence of cutaneous melanoma is rising rapidly in a number of countries. The key environmental risk factor is exposure to the ultraviolet (UV) component in sunlight. The nucleotide excision repair (NER) pathway deals with the main forms of UV-induced DNA damage. We have investigated the hypothesis that polymorphisms in NER genes constitute genetic susceptibility factors for melanoma. However, not all melanomas arise on sun-exposed sites and so we investigated the hypothesis that genes involved in other pathways for the repair of oxidative DNA damage may also be involved in susceptibility to melanoma. Scotland, with its high incidence of melanoma and stable homogeneous population, was ideal for this case-control study, involving 596 Scottish melanoma patients and 441 population-based controls. Significant associations were found for the NER genes ERCC1 and XPF, with the strongest associations for melanoma cases aged 50 and under [ERCC1 odds ratio (OR) 1.59, P = 0.008; XPF OR 1.69, P = 0.003]. Although an XPD haplotype was associated with melanoma, it did not contain the variant 751 Gln allele, which has been associated with melanoma in some previous studies. No associations were found for the base excision repair and DNA damage response genes investigated. An association was also found for a polymorphism in the promoter of the vitamin D receptor gene, VDR (OR 1.88, P = 0.005). The products of the two NER genes, ERCC1 and XPF, where associations with melanoma were found, act together in a rate-limiting step in the repair pathway.

Management of familial melanoma

Relatives of patients with melanoma are at increased risk of melanoma. We review the evidence that this risk may be attributed both to shared susceptibility genes (both high-penetrance and lower-penetrance genes) and shared environment. The most frequent high-penetrance susceptibility gene is CDKN2A, and environmental effects on the risk to gene carriers are evident in that CDKN2A penetrance is higher in CDKN2A-mutation-positive families living in Australia than those in Europe. We review the approaches to managing melanoma families, in which the likelihood of there being detectable CDKN2A mutations is positively correlated with the number of cases of melanoma in the family. Within families, risk that an individual carries a germline mutation can be estimated by pedigree analysis for autosomal dominant genes with incomplete penetrance. Prevention advice to families relates to moderation of sun exposure and self-examination of naevi, although there are few supportive data.

The challenge resulting from positive and negative effects of sunlight: How much solar UV exposure is appropriate to balance between risks of vitamin D deficiency and skin cancer?

There is no doubt that solar ultraviolet (UV) exposure is the most important environmental risk factor for the development of non-melanoma skin cancer. Therefore, sun protection is of particular importance to prevent these malignancies, especially in risk groups. However, 90% of all requisite vitamin D has to be formed in the skin through the action of the sun-a serious problem, for a connection between vitamin D deficiency and a broad variety of independent diseases including various types of cancer, bone diseases, autoimmune diseases, hypertension and cardiovascular disease has now been clearly indicated in a large number of epidemiologic and laboratory studies. An important link that improved our understanding of these new findings was the discovery that the biologically active vitamin D metabolite 1,25(OH)(2)D is not exclusively produced in the kidney, but in many other tissues such as prostate, colon, skin and osteoblasts. Extra-renally produced 1,25(OH)(2)D is now considered to be an autocrine or paracrine hormone, regulating various cellular functions including cell growth. We and others have shown that strict sun protection causes vitamin D deficiency in risk groups. In the light of new scientific findings that convincingly demonstrate an association of vitamin D deficiency with a variety of severe diseases including various cancers, the detection and treatment of vitamin D deficiency in sun-deprived risk groups is of high importance. It has to be emphasized that in groups that are at high risk of developing vitamin D deficiency (e.g., nursing home residents or patients under immunosuppressive therapy), vitamin D status has to be monitored. Vitamin D deficiency should be treated, e.g., by giving vitamin D orally. Dermatologists and other clinicians have to recognize that there is convincing evidence that the protective effect of less intense solar UV radiation outweighs its mutagenic effects. Although further work is necessary to define an adequate vitamin D status and adequate guidelines for solar UV exposure, it is at present mandatory that public health campaigns and recommendations of dermatologists on sun protection consider these facts. Well-balanced recommendations on sun protection have to ensure an adequate vitamin D status, thereby protecting people against adverse effects of strict sun protection without significantly increasing the risk of developing UV-induced skin cancer.

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

Vitamin D receptor (VDR) polymorphisms are prostate cancer risk candidates. We determined if SNPs in haplotype block sub-regions C2 (SNPs C2-1, G/C(3436), C2-2, A/G(3944)) or C1 (C1-1, C/T(20965), C1-2, C/T(30056)) are associated with risk in an ultraviolet radiation (UVR)-dependent manner. In men with very low exposure, SNPs in both sub-regions were associated with risk. Various haplotypes in haplotype block C including G(3436)-A(3944)-C(20965)-C(30056), (G or C)-A-C-C and G-A-(C or T)-C were significantly associated with increased risk (odds ratios between 1.95 and 2.37). These findings suggest various block C SNPs are associated with prostate cancer risk via a mechanism involving exposure to sunlight.

Associations between G/A1229, A/G3944, T/C30875, C/T48200 and C/T65013 genotypes and haplotypes in the vitamin D receptor gene, ultraviolet radiation and susceptibility to prostate cancer

Ultraviolet radiation (UVR) may protect against prostate cancer via a mechanism involving vitamin D. Thus, the vitamin D receptor (VDR) gene is a susceptibility candidate, though published data are discrepant. We studied the association of prostate cancer risk with five VDR single nucleotide polymorphisms (SNPs): G/A(1229) (SNP 1), A/G(3944) (SNP 2), T/C(30875) (SNP 3), C/T(48200) (SNP 4) and C/T(65013) (SNP 5), in 430 cancer and 310 benign prostatic hypertrophy (BPH) patients. The SNP 2 GG genotype frequency was lower in cancer than BPH patients (odds ratio = 0.63, 95% CI = 0.41-0.98, p = 0.039). SNPs 1 and 2, and SNPs 4 and 5, were in linkage disequilibrium. Two copies of haplotypes comprising SNPs 1-2, G-G (odds ratio = 0.63, p = 0.039), SNPs 2-3 G-C (odds ratio = 0.45, p = 0.008) and SNPs 1-2-3 G-G-C (odds ratio = 0.44, p = 0.006), but not SNPs 1-3, G-C (odds ratio = 0.81, p = 0.34), were associated with reduced risk (reference, no copies of the haplotypes). These associations were observed after stratification of subjects by extent of UVR exposure. These data show that SNP 2 GG genotype mediates prostate cancer risk, complementing studies reporting this allele is protective in malignant melanoma pathogenesis. They further suggest that published associations of risk with SNP 1 may result from linkage disequilibrium with SNP 2.

Two single-nucleotide polymorphisms in the human vitamin D receptor promoter change protein–DNA complex formation and are associated with height and vitamin D status in adolescent girls

Numerous association studies have dealt with single-nucleotide polymorphisms (SNPs) in coding and intronic regions of the human vitamin D receptor (hVDR) gene. We have hypothesized that phenotypic traits may also be associated with variations in VDR expression due to the presence of SNPs in promoter regions. In this work, we have studied two SNPs located 1521 bp (G/C) and 1012 bp (A/G) upstream of the transcriptional start site of the main human VDR gene promoter. One base-change in any of the two variant sites led to a dramatic change in protein-DNA complex formation using nuclear extracts from HEK293, Caco-2 and COS-7 cells. Genetic analysis of 185 healthy adolescent girls evidenced two major haplotypes: 1521G/1012A and 1521C/1012G and three main genotypes: homozygous for 1521G/1012A (21.1%), homozygous for 1521C/1012G (17.3%) and heterozygous 1521CG/1012GA (57.3%). On the basis of transfection data, promoter activity was nearly 2-fold higher with the 1521G/1012A haplotype, when compared with the 1521C/1012G haplotype. Clinical and biological association study in the adolescent cohort showed that girls with a CC/GG genotype had (i) lower circulating levels of 25-dihydroxyvitamin D, with no detectable consequence on calcium metabolism, (ii) lower serum IGF-1 levels and (iii) smaller height from 11 years of age up to adult height.

Vitamin D receptor gene polymorphisms, particularly the novel A-1012G promoter polymorphism, are associated with vitamin D3 responsiveness and non-familial susceptibility in psoriasis

Psoriasis is a genetically determined disease characterized by hyperproliferation and disordered maturation of the epidermis. Th1 lymphocytes are implicated in its pathogenesis. The vitamin D receptor (VDR) is a candidate modifying gene, having immunosuppressive effects and being involved in anti-proliferative and pro-differentiation pathways in keratinocytes. There is suggestive evidence that the A allele of the A-1012G polymorphism is associated with down-regulation of the Th1 response, via GATA-3. The F and T alleles of Fok1 and Taq1 have been associated with increased VDR activity. The present study aimed to test the hypothesis that the A allele of A-1012G is protective for occurrence and severity of psoriasis and enhances therapeutic response to vitamin D analogues and that these effects would be additive to those of Fok1 and Taq1. The study group comprised 206 psoriasis patients who had received topical calcipotriol treatment and 80 controls. There was no significant linkage disequilibrium between any pair of the three polymorphic sites (P=0.3-0.8). The A, F and T alleles were positively associated with calcipotriol response: AA genotype (compared to AG/GG), odds ratio (OR)=2.18 (P=0.04); TT, OR=1.97 (P=0.03); AAFF genotype combination, OR=4.11 (P=0.03); AATT, OR=5.64 (P=0.005); and FFTT, OR=3.22 (P=0.01). Comparing patients without, to patients with, a family history of psoriasis, the A allele was under represented (P=0.01) and the AAFF genotype combination even more so (compared to residual genotypes) (OR=0.24; P=0.005). AAFF was also under-represented in patients without a family history compared to controls (OR=0.31; P=0.04). There were no associations of family history with Fok1 and Taq1. There were no associations of severity of psoriasis with any polymorphism. In conclusion, the A-1012G, Fok1 and Taq1 VDR polymorphisms were associated with response to calcipotriol. A-1012G and Fok1 were associated with susceptibility to non-familial psoriasis.

Ultraviolet Radiation, Vitamin D and Risk of Prostate Cancer and Other Diseases

Most common diseases appear to result from complex, poorly understood interactions between genetic and environmental factors. Relatively few factors have been unequivocally linked with disease risk or outcome. Evidence from various studies using different experimental approaches has been interpreted as showing that, apart from its harmful effects on the pathogenesis of the common skin cancers, ultraviolet radiation (UVR) may exert a beneficial effect on development of various internal cancers and other pathologies. This concept is supported by parallel studies showing that hypovitaminosis D is linked with increased risk of various diseases including insulin resistance and multiple sclerosis. These findings suggest that, first, host factors such as skin pigmentation that affect UVR-induced synthesis of vitamin D and, second, polymorphism in genes that mediate the effectiveness of vitamin D action are susceptibility candidates for a variety of diseases. Collectively, these data suggest the hypothesis that, via effects on vitamin D synthesis, UVR exposure has beneficial effects on susceptibility and outcome to a variety of complex diseases. We describe evidence from studies in various diseases, but mainly from prostate cancer patients, that supports this hypothesis, but we emphasize that, although supportive data are available, the concept is unproven. Indeed, other explanations are possible. However, given the potentially important public health implications of the hypothesis and the potential for the development of novel therapeutic modalities, we believe the concept is worthy of further investigation.