key: cord-0005646-e9z0cdc5
authors: Campbell, Moray J.; Trump, Donald L.
title: Vitamin D Receptor Signaling and Cancer
date: 2017-09-29
journal: Endocrinol Metab Clin North Am
DOI: 10.1016/j.ecl.2017.07.007
sha: 25d69d1d7ef54c470f743b2f819f81536d61df75
doc_id: 5646
cord_uid: e9z0cdc5

nan

In parallel to these VDR-centered discoveries a greater awareness emerged of the 48 members of the nuclear hormone receptor (NR) superfamily, of which the VDR is a member. As a result, the VDR and other NRs represent some of the most well-studied human transcription factors and have yielded significant insight into the mechanisms of transcriptional control.

It is worth stressing the fundamental importance of the precise monitoring and regulation of serum calcium levels to human health; hence, the endocrine role of the VDR in the regulation of calcium homeostasis is critical. The levels of vitamin D depend on cutaneous synthesis initiated by solar radiation and on dietary intake; a decrease of either one or both sources leads to insufficiency. The contribution from the ultraviolet light (UV)-initiated cutaneous conversion of 7-dehydrocholesterol to vitamin D 3 is the greater, contributing more than 90% toward final 1,25(OH) 2 D 3 synthesis in a vitamin D-sufficient individual.

The importance of the relationships between solar exposure and the ability to capture UVmediated energy is underscored by the inverse correlation between human skin pigmentation and latitude and associated 25(OH)D levels. That is, skin pigmentation was lost as humans migrated out of Africa to adjust to life with reduced solar UV exposure. As a result, individual capacity to generate vitamin D 3 in response to solar UV exposure is intimately associated with forebear environmental adaptation. The correct and sufficient level of solar exposure and serum vitamin D 3 are matters of considerable debate, and an Institute of Medicine report 3 in 2010 recommended daily vitamin D 3 intake at the levels of 600 IU/d for most groups in the population (800 IU/d for those >70 years of age). However, this recommendation is not without controversy; parallel reassessment of the vitamin D impact on the prevention of osteoporosis has suggested that the correct level may be as high as 2 to 3000 IU/d, which may reflect more accurately ancestral serum levels. 4 Another challenge is determining how a given intake relates to serum levels among individuals 5, 6 and what are the appropriate biochemical readouts for measuring systemic response.

However, given that there has been a concerted research focus on VDR signaling, there now exists a fairly sophisticated appreciation of this process, and it has been extensively reviewed. [7] [8] [9] [10] [11] [12] [13] cell lines via direct induction of GADD45α. [59] [60] [61] Concomitant with these events is a downregulation of cyclins such as cyclin A, a decrease in kinase activities associated with activated complexes, and ultimately the dephosphorylation of the retinoblastoma protein and sequestration of E2F family members in a repressive complex. 62 Concomitant with changes in the cell cycle, 1,25(OH) 2 D 3 induces differentiation, most clearly evident in myeloid cell lines, but also supported by other cell types and most likely reflects the intimate links that exist between the regulation of the G 1 transition and the induction of cellular differentiation. [63] [64] [65] [66] [67] [68] [69] [70] [71] [72] Programmed cell death has been reported in breast cancer models and leukemia models, [73] [74] [75] [76] with evidence that the levels of BCL-2 family of proteins are tightly regulated. 77 Treatment with 1α,25(OH) 2 D 3 upregulates vitamin D upregulated protein 1, which binds to the disulfide reducing protein thioredoxin and inhibits its ability to neutralize reactive oxygen species, which in turn can lead to stress-induced apoptosis. [78] [79] [80] Tissue Invasion and Metastasis VDR signaling enhances adhesion and suppresses the invasive capacity of cells; many of these effects are associated with a more differentiated phenotype. In an elegant series of studies, Munoz and coworkers have dissected the relationships between VDR signaling and invasion in colon cancer cell lines and primary tumors. [81] [82] [83] [84] [85] [86] These workers established the delicate interplay between VDR, E-cadherin, and the Wnt signaling pathway in cell lines and clinical samples. Others have examined adhesion protein expression in other cancer models, suggesting that these mechanisms may be generalizable beyond colon cancer cells. 38, [87] [88] [89] 

An essential component of cancer is the ability to replicate without limits that often requires silencing of mechanisms of genomic surveillance. The VDR seems to play roles in maintaining genomic integrity and facilitating DNA repair. There is close cooperation between VDR actions and the p53 tumor suppressor pathway. Correlative data suggest that, generally, cells that respond to 1,25(OH) 2 D 3 most profoundly have wild-type p53, and at the molecular level several target genes are shared by both signaling pathways, such as CDKN1A and GADD45A. 53, 54, 59, [90] [91] [92] [93] [94] [95] Notably in the skin, VDR signaling is combined with surveillance of genomic damage to regulate mitosis negatively. 96, 97 In other epithelial tissues, close cooperation between VDR regulates BRCA1 mRNA and protein via transcriptional activation, again supporting a role in genomic surveillance. [98] [99] [100] 

role of cross-talk between VDR and transforming growth factor (TGF)-β signaling has been revealed. 112, 113 In addition, similar studies have shown that VDR transcriptional targets can distinguish leukemia aggressiveness. 114 The list of gene targets that is common across cell models seems to be short; the most clearly shared target is CYP24A1. Beyond that, commonly enriched gene networks often focus on cell cycle control and signal transduction. However, substantial variations in experimental design (eg, dose, exposure time, and use of 1,25(OH) 2 D 3 or an analog) limit strict comparisons. Thus, although a formal metaanalysis to reveal common themes has not been applied, 115, 116 it seems clear that there is little overlap between the transcriptomic studies. It is also noteworthy that datasets have been developed that are aimed at noncoding RNA species. 117, 118 Therefore, the diversity of the VDR regulated transcriptome is likely to increase.

More recently, these transcriptomic studies have been complemented by VDR ChIP-Seq studies in which the VDR genomic binding patterns have been captured. VDR ChIP-seq studies have been performed in several human cell types, [119] [120] [121] [122] [123] in the presence and/or absence of ligand, and revealed the impact of ligand binding on VDR genomic targeting. Arguably, VDR ChIP-seq studies are more important than transcriptomic studies because they reveal direct VDR genomic interactions, whereas transcriptomic analyses inevitably include direct and indirect VDR-mediated effects. Each VDR ChIP-Seq analysis revealed approximately 2000 to 6000 genomic loci normally distributed around transcription start sites, reflecting the binomial distributions found for other transcription factors, 123,124 but many loci are found at considerable distance from the transcription start sites. Another important finding from these studies is that the dual hexameric DNA motif spaced by 3 bp, a so-called DR3 motif, 125, 126 is found in the majority but not all of the most prominent genomic VDR binding sites. Other binding motifs have also been suggested, for example, an inverted palindrome spaced by 9 bp, a so-called IP-9. 127, 128 The application of ChIP-Seq approaches to NRs in general has revealed greater binding site diversity than previously expected; in addition the importance of flanking regions for cofactors to be biologically important to determine function. 129 These aspects of transcriptional regulation are described in greater depth in J. Wesley Pike and Sylvia Christakos' article, "Biology and Mechanisms of Action of the Vitamin D Hormone," in this issue.

The precise frequency of DR3 type elements in part remains ambiguous, because it depends on a number of variables that include the depth of the sequence read, the precise discovery motif algorithm applied, and the statistical thresholds used. Regardless of the actual percentage of VDR binding sites that contain DR3 motifs, it is clear that the VDR binds in significant levels to genomic regions that do not contain a canonical DR3. This may be explained by the VDR interacting with the genome in both direct (VDR-DNA) and indirect (VDR-protein-DNA) modes (reviewed in reference 8 ).

There is a compelling case to be made for the reanalysis of the VDR ChIP-Seq data, from genomic alignment to differential peak calling. The rationale for reanalyses is two-part. Analyses of ChIP-Seq is not trivial in terms of statistical assumptions, and the existing studies have all been analyzed in a different manner. Therefore, there is the possibility that thresholds and cutoffs differ between studies. Second, the methodologies for ChIP-Seq processing are an area of active development and advancement, and the most recent approaches display a number of benefits over earlier analytical workflows. 130 

Given this wealth of understanding of the broad anticancer actions of the VDR, and the aim to exploit this understanding in cancer settings, the use of rodent models is a major intermediary step before clinical exploitation of VDR signaling in either chemoprevention or chemotherapy settings.

A clear difficulty in investigating the efficacy of targeting VDR with either 1,25(OH) 2 D 3 or analogues that have more attractive pharmacologic propterits 33, 126, [131] [132] [133] [134] [135] [136] [137] [138] [139] [140] is that mice are not humans. Their spectra of age-associated malignancies are different from humans and other key metabolic differences exist. Recapitulating these lifetime effects are further compounded by the need to establish the window in which chemoprevention effects may play a role in either tumor initiation or progression.

Notwithstanding these caveats, the Vdr −/− animals are extremely useful tools to elucidate more clearly the role for the VDR to act in a cancer preventive manner. 2, 141, 142 A series of animals have been generated in which the VDR-ablated background has been crossed into animals with tumor disposition phenotypes. In the first instance, there is evidence that deleting or reducing VDR levels alters the morphology in the colon 143, 144 and breast. 145 Furthermore, crossing the Vdr-deficient and heterozygote mice with mouse mammary tumor virus-neu transgenic mice has generated animals that show a degree of Vdr haplosufficiency. 145 The mammary tumor burden in the crossed mice is reduced with the presence of one wild-type Vdr allele and further with 2 wild-type Vdr alleles. Alternatively, the Vdr −/− animals demonstrate greater susceptibility to carcinogen challenge. For example, challenging Vdr −/− mice with DMBA induced more preneoplastic lesions in the mammary glands than in wild-type mice. 146 Previously, other workers have established that deletion of the Adenomatous polyposis coli (Apc) gene in a mouse can faithfully recapitulate human colon cancer. In turn, these mice have been exploited to examine the impact of Vdr deletion on the progression of colon cancer 147 ; similar studies support an antitumorogenic role for the VDR in the skin. 148 Numerous studies have examined the ability of dietary or pharmacologic addition of vitamin D compounds to either prevent tumor formation or inhibit the growth of xenograft tumors. 82, [149] [150] [151] [152] [153] [154] [155] [156] [157] [158] [159] One area of investigation is the impact of experimental dietary variations and their impact on tumor predisposition. Long-term studies of mice fed with a Western-style diet (eg, high fat and phosphate and low vitamin D and calcium content) have been exploited to examine the impact of vitamin D on colon cancer proliferation. 160 Similarly, vitamin D and calcium dietary interventions and can modulate colon crypt hyperplasia 161 and provide a rationale for how diet, inflammation, and premalignant cells could all interact and modulate cancer progression. 143, [162] [163] [164] [165] 

Epidemiologic studies by Cedric Garland and coworkers were the first to investigate relationships between intensity of sunlight exposure and cancer incidence and revealed an inverse correlation with risk of colon cancer, and subsequently extended these findings to implicate a relationship with other cancers. [166] [167] [168] [169] [170] For example, levels of 25OH-D, the major circulating metabolite of vitamin D, are significantly lower in breast cancer patients than in age-matched controls. [171] [172] [173] However, these relationships are clearly complex and reflect lifetime exposures, and indeed controlling for lifestyle factors can significantly impact the strength of the relationships. 174 Although these are all association studies, and therefore function cannot be readily inferred, there are some suggestive findings that low serum levels of 25OH-D are an unfavorable prognostic indicator [175] [176] [177] [178] or may trigger worse chemotherapy responses. 179 In other cancers, prostate for example, the relationships are more equivocal, with some positive findings, 180, 181 although more generally the results are not able to support a cancer-preventative impact of vitamin D levels. [182] [183] [184] [185] To address these ambiguities, investigators are now in the first stages of randomized supplementation trials, 186 one of which, VITAL (VITamin D and omega-3 TriaL), has now accrued 25,000 people and is examining the impact of supplementing vitamin D and omega 3 fatty acid on a range of pathologies, principally cancer and heart disease incidence 187 Collectively, these preclinical studies and aspects of the epidemiologic findings encouraged academic and pharmaceutical partnerships in the design of vitamin D analogues that may have an optimal balance of in vivo properties to be used as a chemoprevention or chemotherapy agent. Optimizing vitamin D compounds for in vivo anticancer efficacy is aimed at ensuring a favorable balance between calcium mobilizing actions, which result in hypercalcemia, and enhancing the anticancer actions of targeting the VDR. Several medicinal chemistry groups undertook this goal, led in many ways by the group of Milan Uskokovic at Hoffman la Roche, 64, [188] [189] [190] [191] [192] [193] [194] [195] [196] [197] [198] [199] [200] alongside Lisa Binderup at Leo Pharmaceuticals, [201] [202] [203] [204] as well as other groups in academic settings, including Gary Posner. [205] [206] [207] [208] Together, these and other investigators have synthesized a blizzard of vitamin D analogues that have many promising properties, being resistant to metabolism and yet have tolerable impact on serum calcium levels.

Several of these analogues have served as the lead compounds in the search for disease settings where the anticancer actions of vitamin D compounds can be exploited. For example, phase I trials have been undertaken in a range of advanced cancers 209, 210 and led to more targeted phase II trials in pancreatic, 211 liver, 212 prostate, [213] [214] [215] [216] and breast cancers. 186, 217 In all cases, the regimens were well-tolerated but clinical responses were at times modest. However, this in part may reflect that the doses chosen were too conservative and the correct endpoints for these trials would be measuring cellular differentiation (or reduced proliferation or enhanced apoptosis), and this is not readily undertaken in the context of clinical trials.

These challenges are illustrated by considering prostate cancer in more detail. A number of investigators have considered the option of treating men with localized disease before surgery and then studying the prostate tumor after surgery for characterization of known VDR target genes. In a trial of nearly 40 patients with localized prostate cancer, Beer and colleagues 218 administered either 1,25(OH) 2 D 3 or placebo for 4 weeks before radical prostatectomy. Expression changes in the VDR or known candidate VDR target genes of markers of cell proliferation were examined. Interestingly VDR was downregulated in the treatment group, whereas the other genes chosen (eg, TGFBR2) were unchanged. Others replicated this approach but with doxercalciferol and revealed significant modulation of TGFBR2. Interestingly, microarray studies of 1,25(OH) 2 D 3 sensitivity in isogenic breast cancer cell lines established that TGFBR2 was a critical mediator and marker of sensitivity toward 1,25(OH) 2 D 3 . 112 Other investigators have examined the question of efficacy by escalating dose to assess how well higher levels of 1,25(OH) 2 D 3 can be tolerated. 219 Together these studies suggest that 1,25(OH) 2 D 3 can be given to prostate cancer patients at quite high doses and changes in expression of VDR-dependent genes can be observed.

This finding has also led others to consider how chemotherapy with 1,25(OH) 2 D 3 could be potentiated by combinations with other cytotoxic agents for added clinical benefit. Such combination studies are intrinsically challenging; in the vitamin D arena, Novocea undertook such an approach in their development of DN-101 (a new formulation of 1,25(OH) 2 D 3 ) as a cancer therapy in combination with docetaxel for men with advanced prostate cancer that had failed hormonal therapy, so-called castration resistant prostate cancer. Based on numerous preclinical studies and a single institution clinical study, Novocea conducted a randomized phase III study (ASCENT I [AIPC Study of Calcitriol ENhancing Taxotere]) to determine whether the prostate-specific antigen response rate (defined as a >50% decline in prostate-specific antigen for >1 month) was different for the standard therapy for castration resistant prostate cancer at the time (docetaxel 36 mg/m 2 weekly intravenously for 4 weeks every 6 weeks) compared with the same dose and schedule of docetaxel plus DN-101, 45 mg weekly. 220 Although this study did not meet the prostate-specific antigen response criteria, it did alter the overall survival and therefore justified a large randomized trial to assess survival. This new trial (ASCENT II) was halted before full recruitment because survival in the DN-101 arm was reduced compared with standard of care. However, the ASCENT II trial design was seriously flawed: the chemotherapy in each arm was not equal in efficacy. The design of the trial was docetaxel A + DN-101 versus docetaxel B + placebo. Substantial data existed at the time that the trial was initiated that docetaxel A was clearly inferior to docetaxel B in terms of survival in men with castration resistant prostate cancer. Therefore, the trial was actually designed to ask the question, can DN-101 overcome the inferiority of docetaxel regimen A.

A more fundamental flaw of both trials was that the dose of 1,25(OH) 2 D 3 chosen was neither the biologically optimal nor the maximum tolerated dose. Other studies have clearly shown that a 2 to 3 times higher doses of calcitriol can be given safely to such patients. However, the result of ASCENT II has been interpreted as "calcitriol does not potentiate docetaxel (and hence any chemotherapy) in a large clinical trial." This is a conclusion based on no adequate data. As a result, the application of vitamin D formulations have probably been left in a challenging development point. 221 Given these tantalizing preclinical and epidemiologic findings, the question then is why have the clinical trials not been successful? It is clear that clinical exploitation of any drug is hard, and there is a very high attrition rate of drugs passing from preclinical development to clinical implementation. 222 There are many therapies that struggle to balance preclinical promise with clinical realities, and the clinical development pipeline is often challenged by ensuring optimal clinical trial design, as illustrated by PARP inhibitors and antiangiogenesis therapies 223-227 that, although approved by the US Food and Drug Administration, have required further reanalyses to define optimal efficacy. 228,229 Therefore, it is possible that vitamin D-centered chemotherapies will fall to a similar fate. It may well be that, to date, an incomplete understanding of what are the desirable anticancer actions and inappropriate clinical trial design have impeded clinical success with vitamin D compounds.

A major focus emerged on dissecting how cancer cells vary in their response to 1,25(OH) 2 D 3 . One initial focus was on genetic variation in the 3′ and 5′ regions of the VDR gene itself. [230] [231] [232] [233] For example, a start codon polymorphism in exon II at the 5′ end of the gene, determined using the fok-I restriction enzyme, result in a truncated protein. 234 These findings were initially suggestive of a functional relationship between VDR gene genetic variation and cancer risk, but in larger studies these associations seem to be equivocal, or more nuanced. [235] [236] [237] [238] [239] [240] [241] [242] Indeed, this is also reflected by the fact that the National Human Genome Research Institute genome-wide association studies (GWAS) catalog does not list any genome-wide significant genetic variation that is annotated to the VDR and related to cancer phenotypes; rather the genetic variation of the VDR seems to associate with immune, diabetic, and reproduction phenotypes. [243] [244] [245] Also at the genetic level, various investigators have considered how cell responsiveness to 1,25(OH) 2 D 3 may be determined by the expression of the activating (CYP27B1) and metabolizing (CYP24A1) enzymes. For example, comparative genome hybridization studies found that CYP24A1 is amplified in human breast cancer in relation to paired normal tissue. 246, 247 Others have revealed reduced CYP27B1 mRNA and protein levels in a wide variety of cancer cell lines and primary tumors. [248] [249] [250] [251] [252] [253] [254] Together these findings suggest that cancer cell sensitivity toward 1,25(OH) 2 D 3 may primarily depend on autocrine metabolism in target cells rather than the endocrine synthesis and uptake in target cells. This raises the possibility that local control of these enzymes could be exploited in targeted VDR-centric therapies.

Finally, others have considered how epigenetic mechanisms may disrupt VDR signaling. Evidence for this approach arises from the observation that 1,25(OH) 2 D 3 -reclacitrant cells still often respond transcriptionally, but lack transcriptional responsiveness to antiproliferative target genes such as CDKN1A, but sustain or even enhance induction of CYP24A1 gene. 61, 100, 112, 118, 255 These data suggest that the VDR transcriptome is skewed in cancer cells to disfavor antiproliferative target genes, and that lack of functional VDR alone cannot explain resistance. The interactions of transcriptional corepressors such as NCOR1 and NCOR2/SMRT have been examined to investigate this possibility. 61, [256] [257] [258] [259] [260] [261] In turn, altered VDR-corepressor interactions may form a molecular lesion that could be targeted by cotreatment of 1,25(OH) 2 D 3 plus the HDAC inhibitors. [262] [263] [264] [265] [266] [267] 

Biology is very clearly in the genomic era, in which the sum total of genes, transcripts, proteins and metabolites in cells are captured and analyzed. Arguably, the achievements of the Human Genome Project 268 served as a major catalyst for this approach, and other research consortia have applied similar technologies and approaches to tackle other fundamental challenges in biology. Powerful examples are illustrated by Encyclopedia of DNA coding elements (ENCODE), 269, 270 RoadMap Epigenome, 271 Functional and Taxonomic Analysis of Metagenomes, 272 International Human Epigenome Consortium, 273, 274 the Cancer Genome Atlas (TCGA), 275 and the Genotype-Tissue Expression (GTEx) project. 276 The volume of data generated by these projects is unprecedented and truly transformative in terms of the questions that can be addressed, the manner in which they are tackled, and the how the findings are interpreted and widely translated.

Bioinformatic analyses are central to both the generation of these complex datasets and their investigation. Unbiased bioinformatics analyses can reveal organizational insight that is neither obvious nor intuitive. Unbiased and agnostic analyses are achieved by applying algorithmic approaches that depend on discrete mathematics and information theory, combined with graph theory, data mining, and computer science generally, with a central role for the statistical sciences. In this manner, bioinformatic approaches offer the promise to reveal underlying mechanisms of biology in health and disease.

For example, -omic technologies can be applied to capture genomic structural variants and mutations, gene and protein expression patterns, protein posttranslational modifications, and metabolites across cell states. Bioinformatics analyses is applied to all steps from data capture, to data processing (eg, filtering and normalization), to establishing reproducible changes between states A and B, and to more complex integrative analyses from combining different -omic datasets. The statistical sciences are central to all these steps. The ultimate goal from these workflows is to identify network changes between states, and finally to identify nodes that exert control. Such nodes would then form attractive targets for interventionist wet laboratory-based experiments.

Several points are worth stressing from this theoretic workflow. First, study design and phenotype definition are critical. Second, all analyses include a denominator (eg, the genome, the detectable transcriptome, etc) so that any change is considered against the appropriate backdrop of all events occurring in the cell. Third, all data processing includes normalization across samples, including replicates and states, and subsequent filtering to remove the large component of the signal that is unchanging to, therefore, control the penalties of false discovery. Finally, the integrative steps have very high potential for creativity and novelty. That is, as the volume of publicly available data grows, the statistical approaches and types of data integration that can occur are varied and represent where many of the key biological questions of the future will be framed.

The mechanics of VDR signaling and disruption in cancer can, therefore, be analyzed in the paradigm of mining and analyzing large biological datasets. Therefore, there are several bioinformatics approaches that are applicable to the VDR. In the first instance, applying the genome as the denominator allows the question to be addressed of where VDR biology is significant. For example, in what cancer does a significant role for the VDR emerge when considering all genetic variations or gene expression?

At the simplest, GTEx project 277 and the TCGA data can be investigated to identify in which normal tissue is the VDR most highly expressed, or in what cancer is it most commonly altered. The GTEx data reveal that the VDR is most abundant in tissues of the colon and small intestine, and least abundant in basal ganglia and brain tissues. The TCGA data reveal that the VDR is most commonly altered by deletion in 2 cohorts of adenoid cystic carcinoma of the breast. 278, 279 Interestingly, the GTEx data clearly reflect the focus at the preclinical and epidemiologic level of investigated VDR in colon cancer. However, no studies to date have examined VDR in the context of adenoid cystic carcinoma of breast cancer.

The TCGA 280,281 data are derived from more than 33 different cancer types that were collected from approximately 11,000 patients. The analyses of these data have been the subject of more than 350 papers to date and it is striking that none of these papers identified a genome-wide significant role for disruption or association of the VDR with tumor phenotypes. By comparison, more than 100 TCGA papers report a significant relationship with TP53.

Often, biological signals are extremely contextual. Analyses of myeloid 282 and megakaryocyte 283 cells illustrate that there is a significant role for the VDR to act in distinct transcriptional units that control specific points of cell differentiation. These findings reveal the intricate mechanistic basis to some of the earliest cancer studies on VDR signaling in leukemia, 284, 285 which revealed that exogenous vitamin D compounds can trigger cell differentiation. Therefore, reflecting on the role VDR seems to be playing in myeloid systems, it is worth stressing the apparent importance of VDR in immune phenotypes. That is, GWAS identify significant roles for VDR genetic variation in immune phenotypes. 244, 286, 287 Perhaps reflecting the reproduction-related functions of the VDR in murine systems, 288 the Vdr −/− mice display a mammary gland phenotype, and this genotype can modulate cancer incidence in murine cancer models. 145, 289, 290 However, transcriptional and epigenomic control of breast epithelial systems in human cells does not reveal a genome-wide significant role for the VDR, 291 and the major breast cancer papers from TCGA have not identified a genome-wide significant role for the VDR to act as a cancer driver. [292] [293] [294] [295] Putting these findings together from leukemia and common cancers suggests that the VDR itself does not act as a direct cancer driver, either through loss or gain of function. This finding may limit the likelihood of therapeutic exploitation in the cancer context.

Other approaches can be applied to leverage public data by changing the denominator. It is possible to address questions centered around the VDR and related genes, and thereby limit the penalties of false discovery. For example, previously we analyzed 13 transcription factor families implicated in cancer, including the NR superfamily, across 3000 tumors from 6 different tumor types. [296] [297] [298] [299] [300] Bootstrapping approaches 301 established that, across cancers, only the NR family was significantly downregulated, but was neither significantly mutated nor altered by copy number variation. 302 Within the NRs, we found that several NRs were uniquely suppressed in only one tumor site, including VDR in the colon cancer (COAD) cohort; this finding may reflect the strong expression of VDR in the normal colon. VDR downregulation was not found to be driven by copy number variation or mutation and thus epigenetic mechanisms may be primarily responsible for altered expression. 301, 302 There is a very well-established literature supporting links between corrupted VDR signaling and colon cancer. 85, 147, [303] [304] [305] [306] [307] [308] Our pan-cancer analyses add to these findings, suggesting that loss of VDR-induced growth restraint may be more apparent in colon cancer than in other cancers where alterations are not apparent.

The VDR ChIP-seq data also lend themselves to be combined with other types of publicly available data to ask further questions concerning VDR function. For example, an attractive integration approach is to examine how significant genetic variation in transcription factor binding site can relate to phenotypes and disease susceptibility. Testing the possibility that genetic variation impacts transcription factor function underpins trait differences and disease phenotypes is analytically challenging, given the size of the datasets and the potential for false discovery. Various groups have addressed this challenge; notably, both the ENCODE and Roadmap Epigenome consortia leveraged the remarkable volume of ChIP-seq data they generated and merged the binding sites with GWAS data to reveal and rank sites where single nucleotide polymorphisms (SNPs) seem to have a significant impact on the activity of multiple transcription factors. 124, 271, 309 However, given that VDR has not been considered in any of these consortia, we have recently integrated VDR ChIP-Seq 119-123 with National Human Genome Research Institute GWAS SNPs, and SNPs in linkage disequilibrium, to provide novel insight into the interaction between disease-and phenotype-associated SNPs and VDR binding. From these analyses, we applied transcription factor motif searching and exploited other ChIP-Seq data to identify significant interactions between the VDR and other transcription factors and disease traits. In this manner, we identified genetic variation that was significant at the genome-wide level enriched in VDR binding sites that were shared with nuclear factor-κB binding regions related to immune phenotypes, including self-reported allergy. 310 However, none of the GWAS SNPs identified in VDR binding sites were neither in a DR3 type motif, again underscoring the diversity of VDR binding sites, nor related to cancer phenotypes.

However, there does seem to be a significant relationship between VDR and colon cancer, given that the VDR is highly expressed in the normal colon, associated with the control of local immunity, 82, 308, [311] [312] [313] [314] [315] and that, of all the NRs, the VDR is commonly and significantly downregulated in colon cancer. To test this possibility, we leveraged VDR ChIP-Seq data derived in LS180 colon cancer cells 121 with the expression of VDR target genes in the TCGA-COAD cohort. 298 Clustering the tumors by expression patterns then allowed testing the relationships between expression of VDR target genes and clinical outcome. Expression of VDR target genes were either significantly repressed or activated in the COAD cohort, suggesting that VDR functions in both activating and repressing complexes at the basal (or physiologically activated) state. 316 For instance, LGALS4 is a VDR target gene that is specific to colonic cells and is downregulated in colon cancer, acting as a tumor suppressor, 303, 317, 318 and LGALS4 quartile expression patterns significantly associated with disease-free survival in specific patient subgroups.

A further opportunity available for meaningful data integration of ChIP-Seq studies is in the judicious choice of the cell line of study. For example, there are 3 tier 1 cell lines in the ENCODE project including K562 cells, which has approximately 600 publicly available genome-wide datasets. Therefore, there is an exciting opportunity once VDR ChIP-Seq is undertaken in one of these models in terms of integrative analyses 319 that could leverage ENCODE or RoadMap Epigenome data.

Enthusiasm remains for exploiting vitamin D signaling in cancer systems. This partly reflects that the biology is now very well-understood, that the toxicities associated with vitamin D compounds are easily monitored and managed and that in an era of high dimensional biological data it is possible to measure and dissect the actions of VDR signaling in very great detail. It seems likely that efforts will continue to exploit vitamin D compounds in the clinical setting, and it may well be that by exploiting tools to very accurately measure tumor type and burden will allow vitamin D-centered therapies to be applied with great precision. It seems likely that among the actions of VDR, the immunomodulatory capacity may ultimately be the ones that are most advantageous in cancer therapies. 

Preclinical and epidemiologic data justify the concept that vitamin D compounds could be exploited as a differentiation therapy for a wide range of malignancies.

• Clinical evaluation of vitamin D compounds has been more equivocal and, although biological responses can be measured in vivo, clinical responses have not justified further evaluation.

• Dissecting mechanisms of cellular resistance is one route to defining patient groups with greater precision who may respond more fully to clinical targeting.

• Large genomic and population datasets are available that can be mined to define patient responses more completely and identify which tumor types may be most effectively targeted.

Cloning and expression of full-length cDNA encoding human vitamin D receptor

25-Hydroxyvitamin D3 1alpha-hydroxylase and vitamin D synthesis

The 2011 report on dietary reference intakes for calcium and vitamin D from the institute of medicine: what clinicians need to know

Estimates of optimal vitamin D status

Investigating the patterns and determinants of seasonal variation in vitamin D status in Australian adults: the Seasonal D Cohort Study

Modelling the seasonal variation of vitamin D due to sun exposure

Vitamin D and the RNA transcriptome: more than mRNA regulation

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Molecular approaches for optimizing vitamin D supplementation

The impact of vitamin D in breast cancer: genomics, pathways, metabolism

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Cytoplasmic and nuclear binding components for 1alpha25-dihydroxyvitamin D3 in chick parathyroid glands

Scintillation autoradiographic localization of 1,25-dihydroxyvitamin D3 in chick intestine

1,25-dihydroxyvitamin D3 and malignant melanoma: the presence of receptors and inhibition of cell growth in culture

The induction of differentiation in teratocarcinoma stem cells by retinoic acid

The PML/RAR alpha oncoprotein is a direct molecular target of retinoic acid in acute promyelocytic leukemia cells

The acute promyelocytic leukemiaspecific PML-RAR alpha fusion protein inhibits differentiation and promotes survival of myeloid precursor cells

The PML-RAR alpha fusion mRNA generated by the t(15;17) translocation in acute promyelocytic leukemia encodes a functionally altered RAR

Rearrangements in the second intron of the RARA gene are present in a large majority of patients with acute promyelocytic leukemia and are used as molecular marker for retinoic acid-induced leukemic cell differentiation

Retinoic acid. Inhibition of the clonal growth of human myeloid leukemia cells

Induction of differentiation of the human promyelocytic leukemia cell line (HL-60) by retinoic acid

Retinoic acids in the treatment of acute promyelocytic leukemia

Use of all-trans retinoic acid in the treatment of acute promyelocytic leukemia

Fusion proteins of the retinoic acid receptor-alpha recruit histone deacetylase in promyelocytic leukaemia

Role of the histone deacetylase complex in acute promyelocytic leukaemia

Differentiation therapy

Differentiation agents in cancer therapy

German-Austrian Acute Myeloid Leukemia Study Group and Study Alliance Leukemia. Targeted therapy alone for acute promyelocytic leukemia

Retinoids and rexinoids in cancer prevention: from laboratory to clinic

A review of the chemopreventative effects of oral retinoids for internal neoplasms

Expression of retinoic acid receptorbeta sensitizes prostate cancer cells to growth inhibition mediated by combinations of retinoids and a 19-nor hexafluoride vitamin D3 analog

1 alpha,25-dihydroxyvitamin D3 induces differentiation of human myeloid leukemia cells

Differentiation of mouse myeloid leukemia cells induced by 1 alpha,25-dihydroxyvitamin D3

Genetic signatures of differentiation induced by 1alpha,25-dihydroxyvitamin D3 in human colon cancer cells

19-nor-hexafluoride analogue of vitamin D3: a novel class of potent inhibitors of proliferation of human breast cell lines

Inhibition of proliferation of prostate cancer cells by a 19-nor-hexafluoride vitamin D3 analogue involves the induction of p21waf1, p27kip1 and E-cadherin

Novel 20-epi-vitamin D3 analog combined with 9-cisretinoic acid markedly inhibits colony growth of prostate cancer cells

Antiproliferative effects of 1,25-dihydroxyvitamin D3 on primary cultures of human prostatic cells

Impact of the vitamin D3 receptor on growth-regulatory pathways in mammary gland and breast cancer

Possible role for vitamin D in controlling breast cancer cell proliferation

1,25-dihydroxyvitamin D3 receptors in human epithelial cancer cell lines

The hallmarks of cancer

RB phosphorylation in sodium butyrate-resistant HL-60 cells: crossresistance to retinoic acid but not vitamin D3

1,25(OH)2 vitamin D3 induces elevated expression of the cell cycle-regulating genes P21 and P27 in squamous carcinoma cell lines of the head and neck

Vitamin D2 analog 19-nor-1,25-dihydroxyvitamin D2: antitumor activity against leukemia, myeloma, and colon cancer cells

Vitamin D receptor stable transfection restores the susceptibility to 1,25-dihydroxyvitamin D3 cytotoxicity in a rat glioma resistant clone

Effects of vitamin D3 on proliferation of cancer cells in vitro

Induction of glioma cell death by 1,25(OH)2 vitamin D3: towards an endocrine therapy of brain tumors?

Antiapoptotic action of 1,25-dihydroxyvitamin D3 is associated with increased mitochondrial MCL-1 and RAF-1 proteins and reduced release of cytochrome c

1,25-Dihydroxyvitamin D3 protects HL60 cells against apoptosis but down-regulates the expression of the bcl-2 gene

Transcriptional activation of the Cdk inhibitor p21 by vitamin D3 leads to the induced differentiation of the myelomonocytic cell line U937

Regulation of the human p21(waf1/cip1) gene promoter via multiple binding sites for p53 and the vitamin D3 receptor

Cyclin-dependent kinase inhibitor p27 as a mediator of the G1-S phase block induced by 1,25-dihydroxyvitamin D3 in HL60 cells

p27(Kip1) stabilization and G(1) arrest by 1,25-dihydroxyvitamin D(3) in ovarian cancer cells mediated through down-regulation of cyclin E/cyclin-dependent kinase 2 and Skp1-Cullin-F-box protein/Skp2 ubiquitin ligase

Vitamin D(3) receptor/Sp1 complex is required for the induction of p27(Kip1) expression by vitamin D(3)

Translational control of p27Kip1 accumulation during the cell cycle

G2/M arrest by 1,25-dihydroxyvitamin D3 in ovarian cancer cells mediated through the induction of GADD45 via an exonic enhancer

Regulation of gene Expression by 1alpha,25-dihydroxyvitamin D3 and Its analog EB1089 under growth-inhibitory conditions in squamous carcinoma Cells

Altered SMRT levels disrupt vitamin D3 receptor signalling in prostate cancer cells

Modulation of cell cycle control by vitamin D3 and its analogue, EB1089, in human breast cancer cells

Stable methylation patterns of MYC and other genes regulated during terminal myeloid differentiation

Novel vitamin D analogs that modulate leukemic cell growth and differentiation with little effect on either intestinal calcium absorption or bone mobilization

Induction of differentiation of human promyelocytic leukemia cell line HL-60 by retinoyl glucuronide, a biologically active metabolite of vitamin A

Vitamin D3 derivatives inhibit the differentiation of Friend erythroleukemia cells

Inhibition of DNA synthesis by an inducer of differentiation of leukemic cells, 1 alpha, 25 dihydroxy vitamin D3, precedes down regulation of the c-myc gene

Vitamin D compounds. Effect on clonal proliferation and differentiation of human myeloid cells

Vitamin D(3) promotes the differentiation of colon carcinoma cells by the induction of E-cadherin and the inhibition of beta-catenin signaling

Induction of differentiation by 1alpha-hydroxyvitamin D(5) in T47D human breast cancer cells and its interaction with vitamin D receptors

The role of vitamin D in normal prostate growth and differentiation

Mechanisms of differentiation of U937 leukemic cells induced by GM-CSF and 1,25(OH)2 vitamin D3

Induction of apoptosis by 1,25-dihydroxyvitamin D3 in MCF-7 vitamin D3-resistant variant can be sensitized by TPA

Apoptosis is induced by the active metabolite of vitamin D3 and its analogue EB1089 in colorectal adenoma and carcinoma cells: possible implications for prevention and therapy

Synergistic decrease of clonal proliferation, induction of differentiation, and apoptosis of acute promyelocytic leukemia cells after combined treatment with novel 20-epi vitamin D3 analogs and 9-cis retinoic acid

20-epi-vitamin D3 analogues: a novel class of potent inhibitors of proliferation and inducers of differentiation of human breast cancer cell lines

Characterization of a vitamin D3-resistant MCF-7 cell line

Altered thioredoxin subcellular localization and redox status in MCF-7 cells following 1,25-dihydroxyvitamin D3 treatment

Tumor suppressor VDUP1 increases p27(kip1) stability by inhibiting JAB1

Vitamin D3 up-regulated protein 1 mediates oxidative stress via suppressing the thioredoxin function

Vitamin D receptor expression and associated gene signature in tumour stromal fibroblasts predict clinical outcome in colorectal cancer

Cystatin D is a candidate tumor suppressor gene induced by vitamin D in human colon cancer cells

DICKKOPF-4 is induced by TCF/beta-catenin and upregulated in human colon cancer, promotes tumour cell invasion and angiogenesis and is repressed by 1alpha,25-dihydroxyvitamin D3

The inhibition of Wnt/beta-catenin signalling by 1alpha,25-dihydroxyvitamin D3 is abrogated by Snail1 in human colon cancer cells

The transcription factor SNAIL represses vitamin D receptor expression and responsiveness in human colon cancer

Beta-catenin confers resistance to PI3K and AKT inhibitors and subverts FOXO3a to promote metastasis in colon cancer

The vitamin D analog, MART-10, represses metastasis potential via downregulation of epithelial-mesenchymal transition in pancreatic cancer cells

OH)2D3) signaling capacity and the epithelial-mesenchymal transition in non-small cell lung cancer (NSCLC): implications for use of 1,25(OH)2D3 in NSCLC treatment

1,25-dihydroxyvitamin D3 stimulates the assembly of adherens junctions in keratinocytes: involvement of protein kinase C

Action of low calcemic 1alpha,25-dihydroxyvitamin D3 analogue EB1089 in head and neck squamous cell carcinoma

1,25-dihydroxyvitamin D3 induces programmed cell death in a rat glioma cell line

p21Cip1/WAF1 is important for differentiation and survival of U937 cells

A new series of vitamin D analogs is highly active for clonal inhibition, differentiation, and induction of WAF1 in myeloid leukemia

Posttranscriptional stabilization underlies p53-independent induction of p21WAF1/CIP1/SDI1 in differentiating human leukemic cells

Modulation of the vitamin D3 response by cancerassociated mutant p53

Tumor suppression in skin and other tissues via cross-talk between vitamin D-and p53-signaling

Inactivation of the vitamin D receptor enhances susceptibility of murine skin to UV-induced tumorigenesis

Vitamin D/vitamin D receptor axis regulates DNA repair during oncogene-induced senescence

Cooperation between BRCA1 and vitamin D is critical for histone acetylation of the p21waf1 promoter and growth inhibition of breast cancer cells and cancer stem-like cells

The anti-proliferative effects of 1alpha,25(OH)2D3 on breast and prostate cancer cells are associated with induction of BRCA1 gene expression

Microarray analysis of 1alpha,25-dihydroxyvitamin D3-treated MC3T3-E1 cells

Large-scale in silico and microarray-based identification of direct 1,25-dihydroxyvitamin D3 target genes

Gene expression analysis of 1,25(OH)2D3-dependent differentiation of HL-60 cells: a cDNA array study

Expression profiling in squamous carcinoma cells reveals pleiotropic effects of vitamin D3 analog EB1089 signaling on cell proliferation, differentiation, and immune system regulation

Vitamin D3 induces tolerance in human dendritic cells by activation of intracellular metabolic pathways

25-dihydroxy-vitamin D3 stimulation of bronchial smooth muscle cells induces autocrine, contractility, and remodeling processes

Vitamin D3 suppresses the androgen-stimulated growth of mouse mammary carcinoma SC-3 cells by transcriptional repression of fibroblast growth factor 8

Vitamin D3 modulated gene expression patterns in human primary normal and cancer prostate cells

Vitamin D3 up-regulated protein-1 regulates collagen expression in mesangial cells

Expression profiling confirms the role of endocytic receptor megalin in renal vitamin D3 metabolism

Up-regulation of vitamin D3 up-regulated protein 1 gene in response to 5-fluorouracil in colon carcinoma SW620

Identification of VDR-responsive gene signatures in breast cancer cells

ZEB1 drives epithelial-to-mesenchymal transition in lung cancer

Identification of a molecular signature predictive of sensitivity to differentiation induction in acute myeloid leukemia

ProfileChaser: searching microarray repositories based on genome-wide patterns of differential expression

Ontology-driven indexing of public datasets for translational bioinformatics

LncRNA: a new player in 1alpha, 25(OH)2 vitamin D3/VDR protection against skin cancer formation

VDR regulation of microRNA differs across prostate cell models suggesting extremely flexible control of transcription

A vitamin D receptor/SMAD genomic circuit gates hepatic fibrotic response

Nuclear hormone 1alpha,25-dihydroxyvitamin D3 elicits a genome-wide shift in the locations of VDR chromatin occupancy

VDR/RXR and TCF4/beta-catenin cistromes in colonic cells of colorectal tumor origin: impact on c-FOS and c-MYC gene expression

A ChIP-seq defined genome-wide map of vitamin D receptor binding: associations with disease and evolution

Patterns of genome-wide VDR locations

Landscape of transcription in human cells

Structural analysis of RXR-VDR interactions on DR3 DNA

Transcriptional activity of a fluorinated vitamin D analog on VDR-RXR-mediated gene expression

The anti-proliferative effect of vitamin D3 analogues is not mediated by inhibition of the AP-1 pathway, but may be related to promoter selectivity

Selective recognition of vitamin D receptor conformations mediates promoter selectivity of vitamin D analogs

DNA recognition by thyroid hormone and retinoic acid receptors: 3,4,5 rule modified

From reads to regions: a bioconductor workflow to detect differential binding in ChIP-seq data

Antileukemic effect of a synthetic vitamin D3 analog, HY-11, with low potential to cause hypercalcemia

Structural evaluation of the agonistic action of a vitamin D analog with two side chains binding to the nuclear vitamin D receptor

Evidence for tissue-and cell-type selective activation of the vitamin D receptor by Ro-26-9228, a noncalcemic analog of vitamin D3

Novel 19-nor-hexafluoride vitamin D3 analog (Ro 25-6760) inhibits human colon cancer in vitro via apoptosis

A new analog of 1,25-(OH)2D3, 19-NOR-1,25-(OH)2D2, suppresses serum PTH and parathyroid gland growth in uremic rats without elevation of intestinal vitamin D receptor content

Novel Gemini-vitamin D3 analog inhibits tumor cell growth and modulates the Akt/mTOR signaling pathway

Development of a novel 1,25(OH)2-vitamin D3 analog with potent ability to induce HL-60 cell differentiation without modulating calcium metabolism

Structural studies of vitamin D nuclear receptor ligand-binding properties

Superagonistic fluorinated vitamin D3 analogs stabilize helix 12 of the vitamin D receptor

Superagonistic action of 14-epi-analogs of 1,25-dihydroxyvitamin D explained by vitamin D receptor-coactivator interaction

Rescue of the skeletal phenotype of vitamin D receptor-ablated mice in the setting of normal mineral ion homeostasis: formal histomorphometric and biomechanical analyses

Duodenal calcium absorption in vitamin D receptor-knockout mice: functional and molecular aspects

Characterization of a vitamin D receptor knockout mouse as a model of colorectal hyperproliferation and DNA damage

Lack of vitamin D receptor causes dysbiosis and changes the functions of the murine intestinal microbiome

Vitamin D receptor status alters mammary gland morphology and tumorigenesis in MMTV-neu mice

Vitamin D(3) receptor ablation sensitizes skin to chemically induced tumorigenesis

Vitamin D receptor deficiency enhances Wnt/betacatenin signaling and tumor burden in colon cancer

Overexpression of hedgehog signaling is associated with epidermal tumor formation in vitamin D receptor-null mice

Effects of synthetic vitamin D analogues on breast cancer cell proliferation in vivo and in vitro

Vitamin D receptor-dependent antitumour effects of 1,25-dihydroxyvitamin D3 and two synthetic analogues in three in vivo models of prostate cancer

Growth-inhibitory effects of vitamin D analogues and retinoids on human pancreatic cancer cells

The vitamin D analogue EB 1089 prevents skeletal metastasis and prolongs survival time in nude mice transplanted with human breast cancer cells

Activation of vitamin D receptor signaling down-regulates the expression of nuclear FOXM1 protein and suppresses pancreatic cancer cell stemness

Growth suppression of ovarian cancer xenografts in nude mice by vitamin D analogue EB1089

Vitamin D3 administration induces nuclear p27 accumulation, restores differentiation, and reduces tumor burden in a mouse model of metastatic follicular thyroid cancer

The prostate cancer TMPRSS2:ERG fusion synergizes with the vitamin D receptor (VDR) to induce CYP24A1 expression-limiting VDR signaling

Vitamin D deficiency enhances the growth of MC-26 colon cancer xenografts in Balb/c mice

Inhibition of prostate cancer-meditated osteoblastic bone lesions by the low-calcemic analog 1alpha-hydroxymethyl-16-ene-26,27-bishomo-25-hydroxy vitamin D3

Diet-derived 25-hydroxyvitamin D3 activates vitamin D receptor target gene expression and suppresses EGFR mutant non-small cell lung cancer growth in vitro and in vivo

Western-style diet-induced colonic tumors and their modulation by calcium and vitamin D in C57Bl/6 mice: a preclinical model for human sporadic colon cancer

Vitamin D and its metabolites inhibit cell proliferation in human rectal mucosa and a colon cancer cell line

Colonic vitamin D metabolism: implications for the pathogenesis of inflammatory bowel disease and colorectal cancer

Colon-specific regulation of vitamin D hydroxylases-a possible approach for tumor prevention

Phytoestrogens and vitamin D metabolism: a new concept for the prevention and therapy of colorectal, prostate, and mammary carcinomas

Cross talk between the calcium-sensing receptor and the vitamin D system in prevention of cancer

Vitamin D for cancer prevention: global perspective

Vitamin D and prevention of breast cancer: pooled analysis

Vitamin D and prevention of colorectal cancer

Dietary vitamin D and calcium and risk of colorectal cancer: a 19-year prospective study in men

Do sunlight and vitamin D reduce the likelihood of colon cancer?

Serum 25(OH) vitamin D and risk of breast cancer: a nested case-control study from the French E3N cohort

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

Serum 25-hydroxyvitamin D and risk of post-menopausal breast cancer-results of a large case-control study

Circulating 25-hydroxyvitamin D and postmenopausal breast cancer survival: influence of tumor characteristics and lifestyle factors

Protective links between vitamin D, inflammatory bowel disease and colon cancer

Serum vitamin D (25OHD3) levels and the risk of different subtypes of breast cancer: a nested case-control study

Association of serum level of vitamin D at diagnosis with breast cancer survival: a case-cohort analysis in the pathways study

Prediagnostic plasma 25-hydroxyvitamin D and pancreatic cancer survival

Vitamin D deficiency impairs rituximab-mediated cellular cytotoxicity and outcome of patients with diffuse large B-cell lymphoma treated with but not without rituximab

Vitamin D insufficiency is common in patients with nonmetastatic prostate cancer

Calcium intake and vitamin D metabolism and action, in healthy conditions and in prostate cancer

Circulating vitamin D, vitamin D-related genetic variation, and risk of fatal prostate cancer in the National Cancer Institute Breast and Prostate Cancer Cohort Consortium

Circulating levels of 25-hydroxyvitamin D and prostate cancer prognosis

Serum 25-hydroxy vitamin D and prostate cancer risk in a large nested case-control study

Plasma 25-hydroxyvitamin D and prostate cancer risk: the multiethnic cohort

Impact of a tailored oral vitamin D supplementation regimen on serum 25-hydroxyvitamin D levels in early breast cancer patients: a randomized phase III study

Baseline characteristics of participants in the VITamin D and omega-3 TriaL (VITAL)

Metabolism of selective 20-epi-vitamin D3 analogs in rat osteosarcoma UMR-106 cells: isolation and identification of four novel C-1 fatty acid esters of 1alpha,25-dihydroxy-16-ene-20-epi-vitamin D3

Novel Gemini vitamin D3 analogs: large structure/ function analysis and ability to induce antimicrobial peptide

Structure-function study of gemini derivatives with two different side chains at C-20, Gemini-0072 and Gemini-0097

27-trinorvitamin D3 (cholacalcioic acid): end products of 25-hydroxyvitamin D3 metabolism in rat kidney through C-24 oxidation pathway

C-20 cyclopropyl vitamin D3 analogs

Isolation and identification of 1alpha-hydroxy-24-oxovitamin D3 and 1alpha,23-dihydroxy-24-oxovitamin D3: metabolites of 1alpha,24(R)-dihydroxyvitamin D3 produced in rat kidney

25-dihydroxy-3-epivitamin D3: in vivo metabolite of 1alpha,25-dihydroxyvitamin D3 in rats

Vitamin D analog 25-(OH)-16,23E-Diene-26,27-hexafluoro-vitamin D3 induces differentiation of HL60 cells with minimal effects on cellular calcium homeostasis

Effects of 1alpha,25-dihydroxy-16ene, 23yne-vitamin D3 on osteoblastic function in human osteosarcoma SaOS-2 cells: differentiation-stage dependence and modulation by 17-beta estradiol

19-nor-10-ketovitamin D derivatives: unique metabolites of vitamin D3, vitamin D2, and 25-hydroxyvitamin D3

1 Alpha-25,26-trihydroxyvitamin D3: an in vivo and in vitro metabolite of vitamin D3

Vitamin D3 metabolites. 3. Synthesis and X-ray analysis of 1 alpha,25-dihydroxycholesterol

19-nor vitamin-D analogs: a new class of potent inhibitors of proliferation and inducers of differentiation of human myeloid leukemia cell lines

Vitamin D(3) analogs (MC 1288, KH 1060, EB 1089, GS 1558, and CB 1093): studies on their mechanism of action

The in vitro effect of vitamin D3 analogue EB-1089 on a human prostate cancer cell line (PC-3)

Vitamin D3 analogue (EB 1089) inhibits in vitro cellular proliferation of human colon cancer cells

EB 1089, a novel vitamin D analogue, has strong antiproliferative and differentiation inducing effects on cancer cells

QW-1624F2-2, a synthetic analogue of 1,25-dihydroxyvitamin D3, enhances the response to other deltanoids and suppresses the invasiveness of human metastatic breast tumor cells

Potent, selective and low-calcemic inhibitors of CYP24 hydroxylase: 24-sulfoximine analogues of the hormone 1alpha,25-dihydroxyvitamin D(3)

A non-calcemic analog of 1 alpha,25 dihydroxy vitamin D(3) (JKF) upregulates the induction of creatine kinase B by 17 beta estradiol in osteoblast-like ROS 17/2.8 cells and in rat diaphysis

New vitamin D analogues

A phase I study of the vitamin D analogue EB 1089 in patients with advanced breast and colorectal cancer

A phase I study of the vitamin D3 analogue ILX23-7553 administered orally to patients with advanced solid tumors

A phase II trial of the vitamin D analogue Seocalcitol (EB1089) in patients with inoperable pancreatic cancer

A phase II study of the vitamin D analogue Seocalcitol in patients with inoperable hepatocellular carcinoma

A phase II trial of dexamethasone, vitamin D, and carboplatin in patients with hormone-refractory prostate cancer

Phase IIa, randomized placebo-controlled trial of single high dose cholecalciferol (vitamin D3) and daily Genistein (G-2535) versus double placebo in men with early stage prostate cancer undergoing prostatectomy

Phase 2 trial of weekly intravenous 1,25 dihydroxy cholecalciferol (calcitriol) in combination with dexamethasone for castration-resistant prostate cancer

Phase II trial of oral 1,25-dihydroxyvitamin D (calcitriol) in hormone refractory prostate cancer

A phase 2 trial exploring the effects of high-dose (10,000 IU/day) vitamin D(3) in breast cancer patients with bone metastases

Randomized study of high-dose pulse calcitriol or placebo prior to radical prostatectomy

Randomized clinical trial of vitamin D3 doses on prostatic vitamin D metabolite levels and ki67 labeling in prostate cancer patients

ASCENT (AIPC Study of Calcitriol ENhancing Taxotere) Investigators. Intermittent chemotherapy in patients with metastatic androgen-independent prostate cancer: results from ASCENT, a double-blinded, randomized comparison of high-dose calcitriol plus docetaxel with placebo plus docetaxel

Randomized, open-label phase III trial of docetaxel plus high-dose calcitriol versus docetaxel plus prednisone for patients with castration-resistant prostate cancer

Optimising translational oncology in clinical practice: strategies to accelerate progress in drug development

Phase II study of olaparib (AZD-2281) after standard systemic therapies for disseminated colorectal cancer

Overall survival in patients with platinum-sensitive recurrent serous ovarian cancer receiving olaparib maintenance monotherapy: an updated analysis from a randomised, placebo-controlled, double-blind, phase 2 trial

PARP inhibitors stumble in breast cancer

Phase III trial evaluating the addition of bevacizumab to endocrine therapy as first-line treatment for advanced breast cancer: the letrozole/fulvestrant and avastin (LEA) study

Avastin saga reveals debate over clinical trial endpoints

PARP inhibitors: targeting the right patients

Double-blind phase II trial with prospective classification by ATM protein level to evaluate the efficacy and tolerability of olaparib plus paclitaxel in patients with recurrent or metastatic gastric cancer

Polymorphisms in the vitamin D receptor and risk of ovarian cancer in four studies

Vitamin D receptor gene polymorphisms, dietary promotion of insulin resistance, and colon and rectal cancer

Vitamin D receptor gene polymorphisms in breast cancer

Association of prostate cancer risk with genetic polymorphisms in vitamin D receptor and androgen receptor

Vitamin D receptor gene polymorphisms are associated with breast cancer risk in a UK Caucasian population

Vitamin D receptor gene polymorphisms and esophageal cancer risk in a Chinese population: a negative study

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

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

Genetic polymorphisms in vitamin D metabolism and signaling genes and risk of breast cancer: a nested case-control study

No association between vitamin D intake, VDR polymorphisms, and colorectal cancer in a population-based case-control study

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

Genetic polymorphisms of vitamin D receptor and the risk of prostate cancer: a meta-analysis

Vitamin D receptor gene ApaI polymorphism and breast cancer susceptibility: a meta-analysis

Parent-of-origin-specific allelic associations among 106 genomic loci for age at menarche

Host-microbe interactions have shaped the genetic architecture of inflammatory bowel disease

Gout and type 2 diabetes have a mutual interdependent effect on genetic risk factors and higher incidences

Cytogenetic characterization and gene expression profiling of the trastuzumab-resistant breast cancer cell line JIMT-1

Quantitative mapping of amplicon structure by array CGH identifies CYP24 as a candidate oncogene

Alterations in vitamin D signalling and metabolic pathways in breast cancer progression: a study of VDR, CYP27B1 and CYP24A1 expression in benign and malignant breast lesions

Comprehensive association analysis of the vitamin D pathway genes, VDR, CYP27B1, and CYP24A1, in prostate cancer

Relative expression of vitamin D hydroxylases, CYP27B1 and CYP24A1, and of cyclooxygenase-2 and heterogeneity of human colorectal cancer in relation to age, gender, tumor location, and malignancy: results from factor and cluster analysis

Regulation of extrarenal vitamin D metabolism as a tool for colon and prostate cancer prevention

MicroRNA-195 inhibits proliferation, invasion and metastasis in breast cancer cells by targeting FASN, HMGCR, ACACA and CYP27B1

Mechanisms of decreased Vitamin D 1alpha-hydroxylase activity in prostate cancer cells

Autocrine metabolism of vitamin D in normal and malignant breast tissue

Regulation of CYP24 splicing by 1,25-dihydroxyvitamin D(3) in human colon cancer cells

Recruitment of NCOR1 to VDR target genes is enhanced in prostate cancer cells and associates with altered DNA methylation patterns

NCoR and SMRT) as well as coactivators are recruited to positively regulated 1alpha,25-dihydroxyvitamin D3-responsive genes

Elevated NCOR1 disrupts a network of dietary-sensing nuclear receptors in bladder cancer cells

Cyclical chromatin looping and transcription factor association on the regulatory regions of the p21 (CDKN1A) gene in response to 1alpha,25-dihydroxyvitamin D3

Overexpression of ER and VDR is not sufficient to make ER-negative MDA-MB231 breast cancer cells responsive to 1alpha-hydroxyvitamin D5

25-Dihydroxyvitamin D3 inhibits transcriptional potential of nuclear factor kappa B in breast cancer cells

Incorporation of histone deacetylase inhibition into the structure of a nuclear receptor agonist

Synergistic growth inhibition of prostate cancer cells by 1 alpha,25 Dihydroxyvitamin D(3) and its 19-nor-hexafluoride analogs in combination with either sodium butyrate or trichostatin A

The TGFbeta/Smad 3-signaling pathway is involved in butyrate-mediated vitamin D receptor (VDR)-expression

Butyrate-induced differentiation of Caco-2 cells is mediated by vitamin D receptor

1,25-Dihydroxycholecalciferol enhances butyrate-induced p21(Waf1/Cip1) expression

Distinct HDACs regulate the transcriptional response of human cyclin-dependent kinase inhibitor genes to Trichostatin A and 1alpha,25-dihydroxyvitamin D3

A history of the human genome project

The making of ENCODE: lessons for big-data projects

Identification and analysis of functional elements in 1% of the human genome by the ENCODE pilot project

Integrative analysis of 111 reference human epigenomes

FANTOM: functional and taxonomic analysis of metagenomes

The International human epigenome consortium data portal

Genetic drivers of epigenetic and transcriptional variation in human immune cells

The Cancer Genome Atlas Pan-Cancer analysis project

Human genomics. The human transcriptome across tissues and individuals

The Genotype-Tissue Expression (GTEx) project

Genomic landscape of adenoid cystic carcinoma of the breast

The mutational landscape of adenoid cystic carcinoma

The cBio cancer genomics portal: an open platform for exploring multidimensional cancer genomics data

Integrative analysis of complex cancer genomics and clinical profiles using the cBioPortal

Densely interconnected transcriptional circuits control cell states in human hematopoiesis

Gene Ontology-driven transcriptional analysis of CD341 cell-initiated megakaryocytic cultures identifies new transcriptional regulators of megakaryopoiesis

Myeloid metaplasia in vitamin D deficiency rickets

Induction of differentiation of human acute myelogenous leukemia cells: therapeutic implications

Canonical pathways, networks and transcriptional factor regulation by clinical strains of Mycobacterium tuberculosis in pulmonary alveolar epithelial cells

Release of severe acute respiratory syndrome coronavirus nuclear import block enhances host transcription in human lung cells

Transcriptomic analysis reveals key regulators of mammogenesis and the pregnancy-lactation cycle

Accelerated mammary gland development during pregnancy and delayed postlactational involution in vitamin D3 receptor null mice

Vitamin D(3) receptor ablation alters mammary gland morphogenesis

Analysis of normal human mammary epigenomes reveals cell-specific active enhancer states and associated transcription factor networks

Integration of somatic mutation, expression and functional data reveals potential driver genes predictive of breast cancer survival

Comprehensive molecular portraits of invasive lobular breast cancer

Comparison of the genomic landscape between primary breast cancer in African American versus white women and the association of racial differences with tumor recurrence

Activating ESR1 mutations in hormoneresistant metastatic breast cancer

Cancer Genome Atlas Research Network. Comprehensive molecular characterization of urothelial bladder carcinoma

Cancer Genome Atlas Network. Comprehensive molecular portraits of human breast tumours

Comprehensive molecular characterization of human colon and rectal cancer

Comprehensive genomic characterization of head and neck squamous cell carcinomas

Genomic portrait of resectable hepatocellular carcinomas: implications of RB1 and FGF19 aberrations for patient stratification

Cooperative behavior of the nuclear receptor superfamily and its deregulation in prostate cancer

Pan-cancer analyses of the nuclear receptor superfamily

Galectin-4 functions as a tumor suppressor of human colorectal cancer

Galectin-4 reduces migration and metastasis formation of pancreatic cancer cells

Abrogation of galectin-4 expression promotes tumorigenesis in colorectal cancer

Metastatic progression of prostate cancer is mediated by autonomous binding of galectin-4-O-glycan to cancer cells

E-cadherin and vitamin D receptor regulation by SNAIL and ZEB1 in colon cancer: clinicopathological correlations

KDM6B/JMJD3 histone demethylase is induced by vitamin D and modulates its effects in colon cancer cells

Annotation of functional variation in personal genomes using RegulomeDB

Integration of VDR genome wide binding and GWAS genetic variation data reveals co-occurrence of VDR and NF-kB binding that is linked to immune phenotypes

Vitamin D and calcium deficits predispose for multiple chronic diseases

The renin-angiotensin system mediates EGF receptorvitamin d receptor cross-talk in colitis-associated colon cancer

Vitamin D resistance and colon cancer prevention

Macrophage-derived IL-1beta stimulates Wnt signaling and growth of colon cancer cells: a crosstalk interrupted by vitamin D3

Intestinal epithelial vitamin D receptor signaling inhibits experimental colitis

Integrative genomic approaches to dissect clinicallysignificant relationships between the VDR cistrome and gene expression in primary colon cancer

Detection of proteome changes in human colon cancer induced by cell surface binding of growth-inhibitory human galectin-4 using quantitative SILACbased proteomics

Search for epithelial-specific mRNAs in peripheral blood of patients with colon cancer by RT-PCR

Integrative genomic analysis in K562 chronic myelogenous leukemia cells reveals that proximal NCOR1 binding positively regulates genes that govern erythroid differentiation and Imatinib sensitivity