Vitamin D receptor protein expression in tumor tissue and prostate cancer progression

The impact of vitamin D pathway genetic variation and circulating 25-hydroxyvitamin D on cancer outcome: systematic review and meta-analysis

BACKGROUND

Vitamin D has been linked with improved cancer outcome. This systematic review and meta-analysis investigates the relationship between cancer outcomes and both vitamin D-related genetic variation and circulating 25-hydroxyvitamin D (25OHD) concentration.

METHODS

A systematic review and meta-analysis of papers until November 2016 on PubMed, EMBASE and Web of Science pertaining to association between circulating vitamin D level, functionally relevant vitamin D receptor genetic variants and variants within vitamin D pathway genes and cancer survival or disease progression was performed.

RESULTS

A total of 44 165 cases from 64 studies were included in meta-analyses. Higher 25OHD was associated with better overall survival (hazard ratio (HR=0.74, 95% CI: 0.66-0.82) and progression-free survival (HR=0.84, 95% CI: 0.77-0.91). The rs1544410 (BsmI) variant was associated with overall survival (HR=1.40, 95% CI: 1.05-1.75) and rs7975232 (ApaI) with progression-free survival (HR=1.29, 95% CI: 1.02-1.56). The rs2228570 (FokI) variant was associated with overall survival in lung cancer patients (HR=1.29, 95% CI: 1.0-1.57), with a suggestive association across all cancers (HR=1.26, 95% CI: 0.96-1.56).

CONCLUSIONS

Higher 25OHD concentration is associated with better cancer outcome, and the observed association of functional variants in vitamin D pathway genes with outcome supports a causal link. This analysis provides powerful background rationale to instigate clinical trials to investigate the potential beneficial effect of vitamin D in the context of stratification by genotype.

WOMEN IN CANCER THEMATIC REVIEW: New roles for nuclear receptors in prostate cancer

Prostate cancer has, for decades, been treated by inhibiting androgen signalling. This is effective in the majority of patients, but inevitably resistance develops and patients progress to life-threatening metastatic disease - hence the quest for new effective therapies for 'castrate-resistant' prostate cancer (CRPC). Studies into what pathways can drive tumour recurrence under these conditions has identified several other nuclear receptor signalling pathways as potential drivers or modulators of CRPC.The nuclear receptors constitute a large (48 members) superfamily of transcription factors sharing a common modular functional structure. Many of them are activated by the binding of small lipophilic molecules, making them potentially druggable. Even those for which no ligand exists or has yet been identified may be tractable to activity modulation by small molecules. Moreover, genomic studies have shown that in models of CRPC, other nuclear receptors can potentially drive similar transcriptional responses to the androgen receptor, while analysis of expression and sequencing databases shows disproportionately high mutation and copy number variation rates among the superfamily. Hence, the nuclear receptor superfamily is of intense interest in the drive to understand how prostate cancer recurs and how we may best treat such recurrent disease. This review aims to provide a snapshot of the current knowledge of the roles of different nuclear receptors in prostate cancer - a rapidly evolving field of research.

Vitamin D and cancer: does it really matter?

PURPOSE OF REVIEW

This article provides a background for an evidence-based decision regarding the prescription of vitamin D for cancer prevention and improvement of outcomes in oncology.

RECENT FINDINGS

In 2014, Feldman and colleagues published a review suggesting a beneficial role for vitamin D in cancer development. In the same year, a Cochrane meta-analysis that included 18 randomized clinical trials comparing vitamin D administration versus no intervention in healthy population found no difference regarding cancer incidence between the groups. One year later, a phase III trial published in the New England Journal of Medicine did not show any protective effect of vitamin D against adenoma development.

SUMMARY

Vitamin D is well known for its importance in calcium and phosphate homeostasis, being essential for bone mineralization. However, calcitriol, or 1,25-dyhydroxy-vitamin D3, is a multifunctional steroid hormone with many extra skeletal actions and may regulate signaling pathways related to cancer development and progression. In preclinical studies, it was shown that vitamin D can promote cell differentiation and inhibit proliferation, angiogenesis, and cell migration. Inconsistent results are found in epidemiological studies and early trials regarding clinical effects of vitamin D supplementation and cancer in terms of prevention and impact in cancer-related mortality.

Role of vitamin D receptor gene Cdx2 and Apa1 polymorphisms in prostate cancer susceptibility: a meta-analysis

BACKGROUND

Vitamin D receptor (VDR) gene polymorphisms affect the risk of prostate cancer. However, studies investigating the relationship between VDR gene polymorphisms (Cdx2 and ApaI) and prostate cancer risk are equivocal. Therefore, we conducted a meta-analysis of all the studies to review the evidence available.

METHODS

A comprehensive search of PubMed, EMBASE, and ISI Web of Science for studies published until September 2015 was conducted. Odds ratios (ORs) and 95 % confidence intervals (CIs) were analyzed to determine the association between VDR Cdx2 and ApaI polymorphisms, and prostate cancer risk.

RESULTS

The meta-analysis included 10 studies involving 4979 cases and 4380 controls to analyze the VDR Cdx2 polymorphism. An additional 11 studies involving 2837 cases and 2884 controls were analyzed for the VDR ApaI polymorphism. Evidence failed to support the role of VDR Cdx2 and ApaI polymorphisms in prostate cancer. For Cdx2, the pooled OR was 1.11 (95 % CI = 0.93-1.33) for AA vs. GG genotypes, 0.97 (95 % CI = 0.88-1.06) for GA vs. AA genotypes, 0.99 (95 % CI = 0.91-1.08) for AA + GA vs. GG, and 1.12 (95 % CI = 0.95-1.31) for AA vs. GA + GG. No significant relationship was observed in any subgroup analysis based on ethnicity, controls, and Hardy-Weinberg equilibrium (HWE). ORs for the ApaI polymorphism were similar.

CONCLUSIONS

VDR Cdx2 and ApaI polymorphisms are not associated with prostate cancer. Additional evidence is required to confirm this conclusion.

Tumor Expression of Vitamin D Receptor and Breast Cancer Histopathological Characteristics and Prognosis

PURPOSE

Our previous work has shown low serum 25-hydroxyvitamin D concentrations in association with aggressive breast cancer subtypes. Vitamin D receptor (VDR) is central for vitamin D-mediated transcription regulation. Few studies have examined breast VDR expression with tumor characteristics or patient survival.

EXPERIMENTAL DESIGN

VDR expression in breast tumor tissue microarrays was determined by immunohistochemistry in 1,114 female patients as low, moderate, and strong expression based on an immunoreactive score, and examined with histopathologic tumor characteristics and survival outcomes including progression-free survival, breast cancer-specific survival, and overall survival.

RESULTS

A majority (58%) of breast tumors showed moderate or strong VDR expression. VDR expression was inversely related to aggressive tumor characteristics, including large tumor size, hormonal receptor (HR) negativity, and triple-negative subtype (P < 0.05). In addition, VDR expression was also inversely related to Ki-67 expression among patients older than 50 years. Nevertheless, VDR expression was not associated with any patient survival outcomes examined.

CONCLUSIONS

In a large patient population, VDR expression is inversely associated with more aggressive breast cancer, but not with breast cancer survival outcomes. The present findings of VDR expression are consistent with our previous results of circulating vitamin D biomarkers, which provide two converging lines of evidence supporting the putative benefits of vitamin D against aggressive breast cancer. Because of the observational nature of our analyses, future studies are warranted to establish the causality of the reported associations. Clin Cancer Res; 23(1); 97-103. ©2016 AACR.

Systems analysis of the prostate transcriptome in African-American men compared with European-American men

AIM

African-Americans (AA) have increased prostate cancer risk and a greater mortality rate than European-Americans (EA). AA exhibit a high prevalence of vitamin D deficiency. We examined the global prostate transcriptome in AA and EA, and the effect of vitamin D₃ supplementation.

PATIENTS & METHODS

Twenty-seven male subjects (ten AA and 17 EA), slated to undergo prostatectomy were enrolled in the study. Fourteen subjects received vitamin D₃ (4000 IU daily) and 13 subjects received placebo for 2 months prior to surgery.

RESULTS

AA show higher expression of genes associated with immune response and inflammation.

CONCLUSION

Systems level analyses support the concept that Inflammatory processes may contribute to disease progression in AA. These transcripts can be modulated by a short course of vitamin D₃ supplementation.

Calcium-Sensing Receptor Tumor Expression and Lethal Prostate Cancer Progression

CONTEXT

Prostate cancer metastases preferentially target bone, and the calcium-sensing receptor (CaSR) may play a role in promoting this metastatic progression.

OBJECTIVE

We evaluated the association of prostate tumor CaSR expression with lethal prostate cancer.

DESIGN

A validated CaSR immunohistochemistry assay was performed on tumor tissue microarrays. Vitamin D receptor (VDR) expression and phosphatase and tensin homolog tumor status were previously assessed in a subset of cases by immunohistochemistry. Cox proportional hazards models adjusting for age and body mass index at diagnosis, Gleason grade, and pathological tumor node metastasis stage were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the association of CaSR expression with lethal prostate cancer.

SETTING

The investigation was conducted in the Health Professionals Follow-up Study and Physicians' Health Study.

PARTICIPANTS

We studied 1241 incident prostate cancer cases diagnosed between 1983 and 2009.

MAIN OUTCOME

Participants were followed up or cancer-specific mortality or development of metastatic disease.

RESULTS

On average, men were followed up 13.6 years, during which there were 83 lethal events. High CaSR expression was associated with lethal prostate cancer independent of clinical and pathological variables (HR 2.0; 95% CI 1.2-3.3). Additionally, there was evidence of effect modification by VDR expression; CaSR was associated with lethal progression among men with low tumor VDR expression (HR 3.2; 95% CI 1.4-7.3) but not in cases with high tumor VDR expression (HR 0.8; 95% CI 0.2-3.0).

CONCLUSIONS

Tumor CaSR expression is associated with an increased risk of lethal prostate cancer, particularly in tumors with low VDR expression. These results support further investigating the mechanism linking CaSR with metastases.

Markers of Vitamin D Exposure and Esophageal Cancer Risk: A Systematic Review and Meta-analysis

Vitamin D has been associated with reduced risk of many cancers, but evidence for esophageal cancer is mixed. To clarify the role of vitamin D, we performed a systematic review and meta-analysis to evaluate the association of vitamin D exposures and esophageal neoplasia, including adenocarcinoma, squamous cell carcinoma (SCC), Barrett's esophagus, and squamous dysplasia. Ovid MEDLINE, EMBASE, and Web of Science were searched from inception to September 2015. Fifteen publications in relation to circulating 25-hydroxyvitamin D [25(OH)D; n = 3], vitamin D intake (n = 4), UVB exposure (n = 1), and genetic factors (n = 7) were retrieved. Higher [25(OH)D] was associated with increased risk of cancer [adenocarcinoma or SCC, OR = 1.39; 95% confidence interval (CI), 1.04-1.74], with the majority of participants coming from China. No association was observed between vitamin D intake and risk of cancer overall (OR, 1.03; 0.65-1.42); however, a nonsignificantly increased risk for adenocarcinoma (OR, 1.45; 0.65-2.24) and nonsignificantly decreased risk for SCC (OR, 0.80; 0.48-1.12) were observed. One study reported a decreased risk of adenocarcinoma with higher UVB exposure. A decreased risk was found for VDR haplotype rs2238135(G)/rs1989969(T) carriers (OR, 0.45; 0.00-0.91), and a suggestive association was observed for rs2107301. In conclusion, no consistent associations were observed between vitamin D exposures and occurrence of esophageal lesions. Further adequately powered, well-designed studies are needed before conclusions can be made. Cancer Epidemiol Biomarkers Prev; 25(6); 877-86. ©2016 AACR.

Associations Between Serum Vitamin D and Adverse Pathology in Men Undergoing Radical Prostatectomy

PURPOSE

Lower serum vitamin D levels have been associated with an increased risk of aggressive prostate cancer. Among men with localized prostate cancer, especially with low- or intermediate-risk disease, vitamin D may serve as an important biomarker of disease aggression. The aim of this study was to assess the relationship between adverse pathology at the time of radical prostatectomy and serum 25-hydroxyvitamin D (25-OH D) levels.

METHODS

This cross-sectional study was carried out from 2009 to 2014, nested within a large epidemiologic study of 1,760 healthy controls and men undergoing prostate cancer screening. In total, 190 men underwent radical prostatectomy in the cohort. Adverse pathology was defined as the presence of primary Gleason 4 or any Gleason 5 disease, or extraprostatic extension. Descriptive and multivariate analyses were performed to assess the relationship between 25-OH D and adverse pathology at the time of prostatectomy.

RESULTS

Eighty-seven men (45.8%) in this cohort demonstrated adverse pathology at radical prostatectomy. The median age in the cohort was 64.0 years (interquartile range, 59.0 to 67.0). On univariate analysis, men with adverse pathology at radical prostatectomy demonstrated lower median serum 25-OH D (22.7 v 27.0 ng/mL, P = .007) compared with their counterparts. On multivariate analysis, controlling for age, serum prostate specific antigen, and abnormal digital rectal examination, serum 25-OH D less than 30 ng/mL was associated with increased odds of adverse pathology (odds ratio, 2.64; 95% CI, 1.25 to 5.59; P = .01).

CONCLUSION

Insufficiency/deficiency of serum 25-OH D is associated with increased odds of adverse pathology in men with localized disease undergoing radical prostatectomy. Serum 25-OH D may serve as a useful biomarker in prostate cancer aggressiveness, which deserves continued study.

Vitamin D and Immune Response: Implications for Prostate Cancer in African Americans

Prostate cancer (PCa) is the most common cancer among men in the U.S. African American (AA) men have a higher incidence and mortality rate compared to European American (EA) men, but the cause of PCa disparities is still unclear. Epidemiologic studies have shown that vitamin D deficiency is associated with advanced stage and higher tumor grade and mortality, while its association with overall PCa risk is inconsistent. Vitamin D deficiency is also more common in AAs than EAs, and the difference in serum vitamin D levels may help explain the PCa disparities. However, the role of vitamin D in aggressive PCa in AAs is not well explored. Studies demonstrated that the active form of vitamin D, 1,25-dihydroxyvitamin D, has anti-inflammatory effects by mediating immune-related gene expression in prostate tissue. Inflammation also plays an important role in PCa pathogenesis and progression, and expression of immune-related genes in PCa tissues differs significantly between AAs and EAs. Unfortunately, the evidence linking vitamin D and immune response in relation to PCa is still scarce. This relationship should be further explored at a genomic level in AA populations that are at high risk for vitamin D deficiency and fatal PCa.

Calcitriol in Combination Therapy for Prostate Cancer: Pharmacokinetic and Pharmacodynamic Interactions

Epidemiological studies indicate that vitamin D insufficiency could have an etiological role in prostate cancer. In addition, calcitriol, used in combination with currently available drugs, has the potential to potentiate their anticancer effects or act synergistically by inhibiting distinct mechanisms involved in prostate cancer growth. Clinical data have not yet provided sufficient evidence to demonstrate benefit of vitamin D due to the limited and underpowered studies that have been published to date. Here, we review the preclinical and clinical studies that describe the activity of calcitriol, applied either alone or in combination and assessed the mechanistic basis of pharmacodynamic and pharmacokinetic interactions with calcitriol. Important considerations for calcitriol use in combination therapy with respect to safety and clinical outcomes have been discussed. Many of these combinations have therapeutic potential for the treatment of several cancer types and it is anticipated that future clinical research will put emphasis on well‑designed clinical trials to establish efficacy.

Vitamin D Signaling Modulators in Cancer Therapy

The antiproliferative and pro-apoptotic effects of 1α,25-dihydroxycholecalciferol (1,25(OH)2D3, 1,25D3, calcitriol) have been demonstrated in various tumor model systems in vitro and in vivo. However, limited antitumor effects of 1,25D3 have been observed in clinical trials. This may be attributed to a variety of factors including overexpression of the primary 1,25D3 degrading enzyme, CYP24A1, in tumors, which would lead to rapid local inactivation of 1,25D3. An alternative strategy for improving the antitumor activity of 1,25D3 involves the combination with a selective CYP24A1 inhibitor. The validity of this approach is supported by numerous preclinical investigations, which demonstrate that CYP24A1 inhibitors suppress 1,25D3 catabolism in tumor cells and increase the effects of 1,25D3 on gene expression and cell growth. Studies are now required to determine whether selective CYP24A1 inhibitors+1,25D3 can be used safely and effectively in patients. CYP24A1 inhibitors plus 1,25D3 can cause dose-limiting toxicity of vitamin D (hypercalcemia) in some patients. Dexamethasone significantly reduces 1,25D3-mediated hypercalcemia and enhances the antitumor activity of 1,25D3, increases VDR-ligand binding, and increases VDR protein expression. Efforts to dissect the mechanisms responsible for CYP24A1 overexpression and combinational effect of 1,25D3/dexamethasone in tumors are underway. Understanding the cross talk between vitamin D receptor (VDR) and glucocorticoid receptor (GR) signaling axes is of crucial importance to the design of new therapies that include 1,25D3 and dexamethasone. Insights gained from these studies are expected to yield novel strategies to improve the efficacy of 1,25D3 treatment.

Vitamin D and the Epithelial to Mesenchymal Transition

Several studies support reciprocal regulation between the active vitamin D derivative 1α,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) and the epithelial to mesenchymal transition (EMT). Thus, 1,25(OH)₂D₃ inhibits EMT via the induction of a variety of target genes that encode cell adhesion and polarity proteins responsible for the epithelial phenotype and through the repression of key EMT inducers. Both direct and indirect regulatory mechanisms mediate these effects. Conversely, certain master EMT inducers inhibit 1,25(OH)₂D₃ action by repressing the transcription of VDR gene encoding the high affinity vitamin D receptor that mediates 1,25(OH)₂D₃ effects. Consequently, the balance between the strength of 1,25(OH)₂D₃ signaling and the induction of EMT defines the cellular phenotype in each context. Here we review the current understanding of the genes and mechanisms involved in the interplay between 1,25(OH)₂D₃ and EMT.

Vitamin D: Metabolism, Molecular Mechanism of Action, and Pleiotropic Effects

1,25-Dihydroxvitamin D3 [1,25(OH)2D3] is the hormonally active form of vitamin D. The genomic mechanism of 1,25(OH)2D3 action involves the direct binding of the 1,25(OH)2D3 activated vitamin D receptor/retinoic X receptor (VDR/RXR) heterodimeric complex to specific DNA sequences. Numerous VDR co-regulatory proteins have been identified, and genome-wide studies have shown that the actions of 1,25(OH)2D3 involve regulation of gene activity at a range of locations many kilobases from the transcription start site. The structure of the liganded VDR/RXR complex was recently characterized using cryoelectron microscopy, X-ray scattering, and hydrogen deuterium exchange. These recent technological advances will result in a more complete understanding of VDR coactivator interactions, thus facilitating cell and gene specific clinical applications. Although the identification of mechanisms mediating VDR-regulated transcription has been one focus of recent research in the field, other topics of fundamental importance include the identification and functional significance of proteins involved in the metabolism of vitamin D. CYP2R1 has been identified as the most important 25-hydroxylase, and a critical role for CYP24A1 in humans was noted in studies showing that inactivating mutations in CYP24A1 are a probable cause of idiopathic infantile hypercalcemia. In addition, studies using knockout and transgenic mice have provided new insight on the physiological role of vitamin D in classical target tissues as well as evidence of extraskeletal effects of 1,25(OH)2D3 including inhibition of cancer progression, effects on the cardiovascular system, and immunomodulatory effects in certain autoimmune diseases. Some of the mechanistic findings in mouse models have also been observed in humans. The identification of similar pathways in humans could lead to the development of new therapies to prevent and treat disease.

Vitamin D in Prostate Cancer

Metastatic castration-resistant prostate cancer (mCRPC) is a progressive, noncurable disease induced by androgen receptor (AR) upon its activation by tumor tissue androgen, which is generated from adrenal steroid dehydroepiandrosterone (DHEA) through intracrine androgen biosynthesis. Inhibition of mCRPC and early-stage, androgen-dependent prostate cancer by calcitriol, the bioactive vitamin D3 metabolite, is amply documented in cell culture and animal studies. However, clinical trials of calcitriol or synthetic analogs are inconclusive, although encouraging results have recently emerged from pilot studies showing efficacy of a safe-dose vitamin D3 supplementation in reducing tumor tissue inflammation and progression of low-grade prostate cancer. Vitamin D-mediated inhibition of normal and malignant prostate cells is caused by diverse mechanisms including G1/S cell cycle arrest, apoptosis, prodifferentiation gene expression changes, and suppressed angiogenesis and cell migration. Biological effects of vitamin D are mediated by altered expression of a gene network regulated by the vitamin D receptor (VDR), which is a multidomain, ligand-inducible transcription factor similar to AR and other nuclear receptors. AR-VDR cross talk modulates androgen metabolism in prostate cancer cells. Androgen inhibits vitamin D-mediated induction of CYP24A1, the calcitriol-degrading enzyme, while vitamin D promotes androgen inactivation by inducing phase I monooxygenases (e.g., CYP3A4) and phase II transferases (e.g., SULT2B1b, a DHEA-sulfotransferase). CYP3A4 and SULT2B1b levels are markedly reduced and CYP24A1 is overexpressed in advanced prostate cancer. In future trials, combining low-calcemic, potent next-generation calcitriol analogs with CYP24A1 inhibition or androgen supplementation, or cancer stem cell suppression by a phytonutrient such as sulfarophane, may prove fruitful in prostate cancer prevention and treatment.

Evaluating a 4-marker signature of aggressive prostate cancer using time-dependent AUC

BACKGROUND

We previously identified a protein tumor signature of PTEN, SMAD4, SPP1, and CCND1 that, together with clinical features, was associated with lethal outcomes among prostate cancer patients. In the current study, we sought to validate the molecular model using time-dependent measures of AUC and predictive values for discriminating lethal from non-lethal prostate cancer.

METHODS

Using data from the initial study, we fit survival models for men with prostate cancer who were participants in the Physicians' Health Study (PHS; n = 276). Based on these models, we generated prognostic risk scores in an independent population, the Health Professionals Follow-up Study (HPFS; n = 347) to evaluate external validity. In each cohort, men were followed prospectively from cancer diagnosis through 2011 for development of distant metastasis or cancer mortality. We measured protein tumor expression of PTEN, SMAD4, SPP1, and CCND1 on tissue microarrays.

RESULTS

During a median of 11.9 and 14.3 years follow-up in the PHS and HPFS cohorts, 24 and 32 men (9%) developed lethal disease. When used as a prognostic factor in a new population, addition of the four markers to clinical variables did not improve discriminatory accuracy through 15 years of follow-up.

CONCLUSIONS

Although the four markers have been identified as key biological mediators in metastatic progression, they do not provide independent, long-term prognostic information beyond clinical factors when measured at diagnosis. This finding may underscore the broad heterogeneity in aggressive prostate tumors and highlight the challenges that may result from overfitting in discovery-based research.

Vitamin D deficiency predicts prostate biopsy outcomes

PURPOSE

The association between vitamin D and prostate biopsy outcomes has not been evaluated. We examine serum vitamin D levels with prostate biopsy results in men with an abnormal prostate-specific antigen and/or digital rectal examination.

EXPERIMENTAL DESIGN

Serum 25-hydroxyvitamin D (25-OH D) was obtained from 667 men, ages 40 to 79 years, prospectively enrolled from Chicago urology clinics undergoing first prostate biopsy. Logistic regression was used to evaluate the associations between 25-OH D status and incident prostate cancer, Gleason score, and tumor stage.

RESULTS

Among European American (EA) men, there was an association of 25-OH D <12 ng/mL with higher Gleason score ≥ 4+4 [OR, 3.66; 95% confidence interval (CI), 1.41-9.50; P = 0.008] and tumor stage [stage ≥ cT2b vs. ≤ cT2a, OR, 2.42 (1.14-5.10); P = 0.008]. In African American (AA) men, we find increased odds of prostate cancer diagnosis on biopsy with 25-OH D < 20 ng/mL [OR, 2.43 (1.20-4.94); P = 0.01]. AA men demonstrated an association between 25-OH D < 12 ng/mL and Gleason ≥ 4+4 [OR, 4.89 (1.59-15.07); P = 0.006]. There was an association with tumor stage ≥ cT2b vs. ≤ cT2a [OR, 4.22 (1.52-11.74); P = 0.003].

CONCLUSIONS

In AA men, vitamin D deficiency was associated with increased odds of prostate cancer diagnosis on biopsy. In both EA and AA men, severe deficiency was positively associated with higher Gleason grade and tumor stage.

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

BACKGROUND

Evidence from experimental animal and cell line studies supports a beneficial role for vitamin D in prostate cancer (PCa). Although the results from human studies have been mainly null for overall PCa risk, there may be a benefit for survival. This study assessed the associations of circulating 25-hydroxyvitamin D (25(OH)D) and common variations in key vitamin D-related genes with fatal PCa.

METHODS

In a large cohort consortium, 518 fatal cases and 2986 controls with 25(OH)D data were identified. Genotyping information for 91 single-nucleotide polymorphisms (SNPs) in 7 vitamin D-related genes (vitamin D receptor, group-specific component, cytochrome P450 27A1 [CYP27A1], CYP27B1, CYP24A1, CYP2R1, and retinoid X receptor α) was available for 496 fatal cases and 3577 controls. Unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations of 25(OH)D and SNPs with fatal PCa. The study also tested for 25(OH)D-SNP interactions among 264 fatal cases and 1169 controls.

RESULTS

No statistically significant relationship was observed between 25(OH)D and fatal PCa (OR for extreme quartiles, 0.86; 95% CI, 0.65-1.14; P for trend = .22) or the main effects of the SNPs and fatal PCa. There was evidence suggesting that associations of several SNPs, including 5 related to circulating 25(OH)D, with fatal PCa were modified by 25(OH)D. Individually, these associations did not remain significant after multiple testing; however, the P value for the set-based test for CYP2R1 was .002.

CONCLUSIONS

Statistically significant associations were not observed for either 25(OH)D or vitamin D-related SNPs with fatal PCa. The effect modification of 25(OH)D associations by biologically plausible genetic variation may deserve further exploration.

Vitamin D in cancer chemoprevention

CONTEXT

There is increasing evidence that Vitamin D (Vit D) and its metabolites, besides their well-known calcium-related functions, may also exert antiproliferative, pro-differentiating, and immune modulatory effects on tumor cells in vitro and may also delay tumor growth in vivo.

OBJECTIVE

The aim of this review is to provide fresh insight into the most recent advances on the role of Vit D and its analogues as chemopreventive drugs in cancer therapy.

METHODS

A systematic review of experimental and clinical studies on Vit D and cancer was undertaken by using the major electronic health database including ISI Web of Science, Medline, PubMed, Scopus and Google Scholar.

RESULTS AND CONCLUSION

Experimental and clinical observations suggest that Vit D and its analogues may be effective in preventing the malignant transformation and/or the progression of various types of human tumors including breast cancer, prostate cancer, colorectal cancer, and some hematological malignances. These findings suggest the possibility of the clinical use of these molecules as novel potential chemopreventive and anticancer agents.

Vitamin D receptor genetic polymorphisms are associated with PSA level, Gleason score and prostate cancer risk in African-American men

BACKGROUND/AIM

Several studies have revealed an association between single nucleotide polymorphisms (SNPs) in the VDR gene and prostate cancer (PCa) risk in European and Asian populations. To investigate whether VDR SNPs are associated with PCa risk in African-American (AA) men, nine VDR SNPs were analyzed in a case-control study.

MATERIALS AND METHODS

Multiple and binary logistic regression models were applied to analyze the clinical and genotypic data.

RESULTS

rs731236 and rs7975232 were significantly associated with PCa risk (p<0.05). In the analysis of clinical phenotypes, rs731236, rs1544410 and rs3782905 were strongly associated with high PSA level (p<0.05), whereas rs1544410 and rs2239185 showed a statistically significant association with high Gleason score (p<0.05). Haplotype analysis revealed several VDR haplotypes associated with PCa risk. Additionally, a trend existed, where as the number of risk alleles increased in the haplotype, the greater was the association with risk (p-trend=0.01).

CONCLUSION

These results suggest that the VDR SNPs may be associated with PCa risk and other clinical phenotypes of PCa in AA men.

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

PURPOSE

Dysregulated signaling of nuclear transcription factors vitamin D receptor (VDR) and Forkhead box M1 (FOXM1) plays important roles in transformation and tumorigenesis. In this study, we sought to determine whether VDR signaling causally affected FOXM1 signaling in and pathogenesis of pancreatic ductal adenocarcinoma (PDAC).

EXPERIMENTAL DESIGN

Genetic and pharmacologic approaches were used to manipulate VDR signaling. The impacts of altered VDR signaling on FOXM1 expression and function in PDAC cells were determined using molecular and biochemical methods, whereas those on PDAC cell biology and tumorigenicity were determined using in vitro and in vivo experimental systems. The clinical relevance of our findings was validated by analyzing human PDAC specimens.

RESULTS

There was a striking inverse correlation between reduced expression of VDR and increased expression of FOXM1 in human PDAC cells and tissues. Treatment of PDAC cells with 1,25-dihydroxyvitamin D3 (1,25D), its synthetic analogue EB1089 (EB), and VDR transgenics drastically inhibited FOXM1 signaling and markedly suppressed tumor stemness, growth, and metastasis. Mechanistically, 1,25D and EB repressed FOXM1 transcription and reduced the expression level of nuclear FOXM1 protein.

CONCLUSION

Inactivation of Vitamin D/VDR signaling is a critical contributor to PDAC development and progression via elevated expression and function of FOXM1 and enhanced PDAC cell stemness, invasion, and metastasis.

VDR activity is differentially affected by Hic-5 in prostate cancer and stromal cells

Patients with prostate cancer treated with androgen deprivation therapy (ADT) eventually develop castrate-resistant prostate cancer (CRPC). 1,25-Dihydroxyvitamin D3 (1,25D3/calcitriol) is a potential adjuvant therapy that confers antiproliferative and pro-differentiation effects in vitro, but has had mixed results in clinical trials. The impact of the tumor microenvironment on 1,25D3 therapy in patients with CRPC has not been assessed. Transforming growth factor β (TGFβ), which is associated with the development of tumorigenic "reactive stroma" in prostate cancer, induced vitamin D3 receptor (VDR) expression in the human WPMY-1 prostate stromal cell line. Similarly, TGFβ enhanced 1,25D3-induced upregulation of CYP24A1, which metabolizes 1,25D3 and thereby limits VDR activity. Ablation of Hic-5, a TGFβ-inducible nuclear receptor coregulator, inhibited basal VDR expression, 1,25D3-induced CYP24A1 expression and metabolism of 1,25D3 and TGFβ-enhanced CYP24A1 expression. A Hic-5-responsive sequence was identified upstream (392-451 bp) of the CYP24A1 transcription start site that is occupied by VDR only in the presence of Hic-5. Ectopic expression of Hic-5 sensitized LNCaP prostate tumor cells to growth-inhibitory effects of 1,25D3 independent of CYP24A1. The sensitivity of Hic-5-expressing LNCaP cells to 1,25D3-induced growth inhibition was accentuated in coculture with Hic-5-ablated WPMY-1 cells. Therefore, these findings indicate that the search for mechanisms to sensitize prostate cancer cells to the antiproliferative effects of VDR ligands needs to account for the impact of VDR activity in the tumor microenvironment.

IMPLICATIONS

Hic-5 acts as a coregulator with distinct effects on VDR transactivation, in prostate cancer and stromal cells, and may exert diverse effects on adjuvant therapy designed to exploit VDR activity in prostate cancer.

The role of vitamin D in reducing cancer risk and progression

Vitamin D is not really a vitamin but the precursor to the potent steroid hormone calcitriol, which has widespread actions throughout the body. Calcitriol regulates numerous cellular pathways that could have a role in determining cancer risk and prognosis. Although epidemiological and early clinical trials are inconsistent, and randomized control trials in humans do not yet exist to conclusively support a beneficial role for vitamin D, accumulating results from preclinical and some clinical studies strongly suggest that vitamin D deficiency increases the risk of developing cancer and that avoiding deficiency and adding vitamin D supplements might be an economical and safe way to reduce cancer incidence and improve cancer prognosis and outcome.

Androgen receptor and gene network: Micromechanics reassemble the signaling machinery of TMPRSS2-ERG positive prostate cancer cells

Prostate cancer is a gland tumor in the male reproductive system. It is a multifaceted and genomically complex disease. Transmembrane protease, serine 2 and v-ets erythroblastosis virus E26 homolog (TMPRSS2-ERG) gene fusions are the common molecular signature of prostate cancer. Although tremendous advances have been made in unraveling various facets of TMPRSS2-ERG-positive prostate cancer, many research findings must be sequentially collected and re-interpreted. It is important to understand the activation or repression of target genes and proteins in response to various stimuli and the assembly in signal transduction in TMPRSS2-ERG fusion-positive prostate cancer cells. Accordingly, we divide this multi-component review ofprostate cancer cells into several segments: 1) The role of TMPRSS2-ERG fusion in genomic instability and methylated regulation in prostate cancer and normal cells; 2) Signal transduction cascades in TMPRSS2-ERG fusion-positive prostate cancer; 3) Overexpressed genes in TMPRSS2-ERG fusion-positive prostate cancer cells; 4) miRNA mediated regulation of the androgen receptor (AR) and its associated protein network; 5) Quantitative control of ERG in prostate cancer cells; 6) TMPRSS2-ERG encoded protein targeting; In conclusion, we provide a detailed understanding of TMPRSS2-ERG fusion related information in prostate cancer development to provide a rationale for exploring TMPRSS2-ERG fusion-mediated molecular network machinery.

Prostate-specific membrane antigen protein expression in tumor tissue and risk of lethal prostate cancer

BACKGROUND

Overexpression of prostate-specific membrane antigen (PSMA) in tumor tissue and serum has been linked to increased risk of biochemical recurrence in surgically treated prostate cancer patients, but none of the studies have assessed its association with disease-specific mortality.

METHODS

We examined whether high PSMA protein expression in prostate tumor tissue was associated with lethal disease, and with tumor biomarkers of progression, among participants of two U.S.-based cohorts (n = 902, diagnosed 1983-2004). We used Cox proportional hazards regression to calculate multivariable HRs and 95% confidence intervals (CI) of lethal prostate cancer, defined as disease-specific death or development of distant metastases (n = 95). Partial Spearman rank correlation coefficients were used to correlate PSMA with tumor biomarkers.

RESULTS

During an average 13 years of follow-up, higher PSMA expression at prostatectomy was significantly associated with lethal prostate cancer (age-adjusted HRQuartile(Q)4vs.Q1 = 2.42; Ptrend < 0.01). This association was attenuated and nonsignificant (multivariable-adjusted HRQ4vs.Q1 = 1.01; Ptrend = 0.52) after further adjusting for Gleason score and prostate-specific antigen (PSA) at diagnosis. High PSMA expression was significantly (P < 0.05) correlated with higher Gleason score and PSA at diagnosis, increased tumor angiogenesis, lower vitamin D receptor and androgen receptor expression, and absence of ets-related gene (ERG) expression.

CONCLUSIONS

High tumor PSMA expression was not an independent predictor of lethal prostate cancer in the current study. PSMA expression likely captures, in part, malignant features of Gleason grade and tumor angiogenesis.

IMPACT

PSMA is not a strong candidate biomarker for predicting prostate cancer-specific mortality in surgically treated patients.

Multispectral Imaging

The field of anatomic pathology has changed significantly over the last decades and, as a result of the technological developments in molecular pathology and genetics, has had increasing pressures put on it to become quantitative and to provide more information about protein expression on a cellular level in tissue sections. Multispectral imaging (MSI) has a long history as an advanced imaging modality and has been used for over a decade now in pathology to improve quantitative accuracy, enable the analysis of multicolor immunohistochemistry, and drastically reduce the impact of contrast-robbing tissue autofluorescence common in formalin-fixed, paraffin-embedded tissues. When combined with advanced software for the automated segmentation of different tissue morphologies (eg, tumor vs stroma) and cellular and subcellular segmentation, MSI can enable the per-cell quantitation of many markers simultaneously. This article covers the role that MSI has played in anatomic pathology in the analysis of formalin-fixed, paraffin-embedded tissue sections, discusses the technological aspects of why MSI has been adopted, and provides a review of the literature of the application of MSI in anatomic pathology.

Circulating levels of 25-hydroxyvitamin D and prostate cancer prognosis

OBJECTIVES

Ecological, in vitro, and in vivo studies demonstrate a link between vitamin D and prostate tumor growth and aggressiveness. The goal of this study was to investigate whether plasma concentration of vitamin D is associated with survivorship and disease progression in men diagnosed with prostate cancer.

MATERIALS AND METHODS

We conducted a population-based cohort study of 1476 prostate cancer patients to assess disease recurrence/progression and prostate cancer-specific mortality (PCSM) risks associated with serum levels of 25(OH) vitamin D [25(OH)D].

RESULTS

There were 325 recurrence/progression and 95 PCSM events during an average of 10.8 years of follow-up. Serum levels of 25(OH)D were not associated with risk of recurrence/progression or mortality. Clinically deficient vitamin D levels were associated with an increased risk of death from other causes.

CONCLUSIONS

We did not find evidence that serum vitamin D levels measured after diagnosis affect prostate cancer prognosis. Lower levels of vitamin D were associated with risk of non-prostate cancer mortality.

Genetic and molecular differences in prostate carcinogenesis between African American and Caucasian American men

Prostate cancer is the most common non-skin cancer and the second leading cause of cancer-related death for men in the United States. Prostate cancer incidence and associated mortality are highest in African American men in comparison to other races. The observed differences in incidence and disease aggressiveness at presentation support a potential role for different pathways of prostate carcinogenesis between African American and Caucasian men. This review focuses on some of the recent molecular biology discoveries, which have been investigated in prostate carcinogenesis and their likely contribution to the known discrepancies across race and ethnicity. Key discussion points include the androgen receptor gene structure and function, genome-wide association studies and epigenetics. The new observations of the ethnic differences of the ERG oncogene, the most common prostate cancer gene, are providing new insights into ERG based stratification of prostate cancers in the context of ethnically diverse patient populations. This rapidly advancing knowledge has the likely potential to benefit clinical practice. Current and future work will improve the ability to sub-type prostate cancers by molecular alterations and lead to targeted therapy against this common malignancy.

Vitamin D3 supplementation, low-risk prostate cancer, and health disparities

Vitamin D promotes the differentiation of prostate cancer cells, raising the possibility that vitamin D deficiency over time may contribute to the progression from subclinical prostate cancer to clinical disease. Since low-risk prostate cancers are monitored over time in an effort to determine which progress into clinically important, more aggressive cancers, they provide an excellent model in which to study, over an extended period of time, the effects of enhancing vitamin D status and related changes in tumor progression. This is particularly relevant to African-American men, who exhibit a high prevalence of vitamin D deficiency as well as higher incidence of prostate cancer and higher mortality rates from prostate cancer than Caucasians. Our research team has recently completed an open-label clinical trial aimed at assessing the safety and potential efficacy of vitamin D3 supplementation at 4000 international units (IU) per day for one year in subjects diagnosed with early stage, low-risk prostate cancer. The results of this clinical study suggest that supplementation with vitamin D3 at 4000IU per day may benefit patients with early stage, low-risk prostate cancer on active surveillance, because of the improved outcome (a decreased number of positive cores at repeat biopsy) in more than half of the subjects enrolled in the trial. We also observed that, after one year of supplementation, there was no difference in circulating levels of vitamin D between African-American and Caucasian subjects who completed the study. These clinical results also suggest that robust and sustained vitamin D3 supplementation can reduce prostate cancer-related health disparities in African-American men and that these health disparities are at least in part the result of widespread hypovitaminosis D within the African-American population. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Vitamin D Receptor Gene Expression and Function in a South African Population: Ethnicity, Vitamin D and FokI

Polymorphisms of the vitamin D receptor gene (VDR) have been associated inconsistently with various diseases, across populations of diverse origin. The T(f) allele of the functional SNP FokI, in exon 2 of VDR, results in a longer vitamin D receptor protein (VDR) isoform, proposed to be less active. Genetic association of VDR with disease is likely confounded by ethnicity and environmental factors such as plasma 25(OH)D3 status. We hypothesized that VDR expression, VDR level and transactivation of target genes, CAMP and CYP24A1, depend on vitamin D, ethnicity and FokI genotype. Healthy volunteers participated in the study (African, n = 40 and White, n = 20). Plasma 25(OH)D3 levels were quantified by LC-MS and monocytes cultured, with or without 1,25(OH)2D3. Gene expression and protein level was quantified using qRT-PCR and flow cytometry, respectively. Mean plasma 25(OH)D3 status was normal and not significantly different between ethnicities. Neither 25(OH)D3 status nor 1,25(OH)2D3 supplementation significantly influenced expression or level of VDR. Africans had significantly higher mean VDR protein levels (P<0.050), nonetheless transactivated less CAMP expression than Whites. Genotyping the FokI polymorphism by pyrosequencing together with HapMap data, showed a significantly higher (P<0.050) frequency of the CC genotype in Africans than in Whites. FokI genotype, however, did not influence VDR expression or VDR level, but influenced overall transactivation of CAMP and 1,25(OH)2D3-elicited CYP24A1 induction; the latter, interacting with ethnicity. In conclusion, differential VDR expression relates to ethnicity, rather than 25(OH)D3 status and FokI genotype. Instead, VDR transactivation of CAMP is influenced by FokI genotype and, together with ethnicity, influence 1,25(OH)2D3-elicited CYP24A1 expression. Thus, the expression and role of VDR to transactivate target genes is determined not only by genetics, but also by ethnicity and environment involving complex interactions which may confound disease association.

Tumor suppressor microRNAs, miR-100 and -125b, are regulated by 1,25-dihydroxyvitamin D in primary prostate cells and in patient tissue

MiR-100 and miR-125b are lost in many cancers and have potential function as tumor suppressors. Using both primary prostatic epithelial cultures and laser capture-microdissected prostate epithelium from 45 patients enrolled in a vitamin D3 randomized trial, we identified miR-100 and -125b as targets of 1,25-dihydroxyvitamin D3 (1,25D). In patients, miR-100 and -125b levels were significantly lower in tumor tissue than in benign prostate. Similarly, miR-100 and -125b were lower in primary prostate cancer cells than in cells derived from benign prostate. Prostatic concentrations of 1,25D positively correlated with these miRNA levels in both prostate cancer and benign epithelium, showing that patients with prostate cancer may still benefit from vitamin D3. In cell assays, upregulation of these miRNAs by 1,25D was vitamin D receptor dependent. Transfection of pre-miR-100 and pre-miR-125b in the presence or absence of 1,25D decreased invasiveness of cancer cell, RWPE-2. Pre-miR-100 and pre-miR-125b decreased proliferation in primary cells and cancer cells respectively. Pre-miR-125b transfection suppressed migration and clonal growth of prostate cancer cells, whereas knockdown of miR-125b in normal cells increased migration indicates a tumor suppressor function. 1,25D suppressed expression of previously bona fide mRNA targets of these miRNAs, E2F3 and Plk1, in a miRNA-dependent manner. Together, these findings show that vitamin D3 supplementation augments tumor suppressive miRNAs in patient prostate tissue, providing evidence that miRNAs could be key physiologic mediators of vitamin D3 activity in prevention and early treatment of prostate cancer.

ERG induces androgen receptor-mediated regulation of SOX9 in prostate cancer

Fusion of the androgen receptor-regulated (AR-regulated) TMPRSS2 gene with ERG in prostate cancer (PCa) causes androgen-stimulated overexpression of ERG, an ETS transcription factor, but critical downstream effectors of ERG-mediating PCa development remain to be established. Expression of the SOX9 transcription factor correlated with TMPRSS2:ERG fusion in 3 independent PCa cohorts, and ERG-dependent expression of SOX9 was confirmed by RNAi in the fusion-positive VCaP cell line. SOX9 has been shown to mediate ductal morphogenesis in fetal prostate and maintain stem/progenitor cell pools in multiple adult tissues, and has also been linked to PCa and other cancers. SOX9 overexpression resulted in neoplasia in murine prostate and stimulated tumor invasion, similarly to ERG. Moreover, SOX9 depletion in VCaP cells markedly impaired invasion and growth in vitro and in vivo, establishing SOX9 as a critical downstream effector of ERG. Finally, we found that ERG regulated SOX9 indirectly by opening a cryptic AR-regulated enhancer in the SOX9 gene. Together, these results demonstrate that ERG redirects AR to a set of genes including SOX9 that are not normally androgen stimulated, and identify SOX9 as a critical downstream effector of ERG in TMPRSS2:ERG fusion-positive PCa.

Current management of prostate cancer: dilemmas and trials

The past decade has witnessed significant advances in our understanding of the biology of prostate cancer. Androgen ablation/androgen receptor inhibition remains as the mainstay of treatment for advanced prostate cancer. Our understanding of the biology of prostate cancer has increased exponentially owing to advances in molecular biology. With this knowledge many intriguing issues have come to light, which clinicians and scientists alike strive to answer. These include why prostate cancer is so common, what drives the development of prostate cancer at a molecular level, why prostate cancer appears refractory to many families of cytotoxic chemotherapeutics, and why prostate cancer preferentially metastasizes to bone. Two clinical forms of prostate cancer have been identified: indolent organ confined disease, which elderly men often die of, and aggressive metastatic disease. A method of distinguishing between these two forms of the disease at an organ-confined stage remains elusive. Understanding the mechanisms of castrate resistance is a further issue of clinical importance. New trials of treatments, including molecular agents that target prostate cancer from a range of angles, have been instituted over the past 10-15 years. We can look at these trials not only as a chance to investigate the effectiveness of new treatments but also as an opportunity to further understand the complex biology of this disease.

Vitamin D3 supplementation at 4000 international units per day for one year results in a decrease of positive cores at repeat biopsy in subjects with low-risk prostate cancer under active surveillance

CONTEXT

We wanted to investigate vitamin D in low-risk prostate cancer.

OBJECTIVES

The objective of the study was to determine whether vitamin D(3) supplementation at 4000 IU/d for 1 yr is safe and would result in a decrease in serum levels of prostate-specific antigen (PSA) or in the rate of progression.

DESIGN

In this open-label clinical trial (Investigational New Drug 77,839), subjects were followed up until repeat biopsy.

SETTING

All subjects were enrolled through the Medical University of South Carolina and the Ralph H. Johnson Veterans Affairs Medical Center, both in Charleston, SC.

PATIENTS AND OTHER PARTICIPANTS

All subjects had a diagnosis of low-risk prostate cancer. Fifty-two subjects were enrolled in the study, 48 completed 1 yr of supplementation, and 44 could be analyzed for both safety and efficacy objectives.

INTERVENTION

The intervention included vitamin D(3) soft gels (4000 IU).

MAIN OUTCOME MEASURES

Adverse events were monitored throughout the study. PSA serum levels were measured at entry and every 2 months for 1 yr. Biopsy procedures were performed before enrollment (for eligibility) and after 1 yr of supplementation.

RESULTS

No adverse events associated with vitamin D(3) supplementation were observed. No significant changes in PSA levels were observed. However, 24 of 44 subjects (55%) showed a decrease in the number of positive cores or decrease in Gleason score; five subjects (11%) showed no change; 15 subjects (34%) showed an increase in the number of positive cores or Gleason score.

CONCLUSION

Patients with low-risk prostate cancer under active surveillance may benefit from vitamin D(3) supplementation at 4000 IU/d.

Seasonal variation in expression of markers in the vitamin D pathway in prostate tissue

PURPOSE

Recent studies suggest variation in genes along the vitamin D pathway, as well as vitamin D receptor (VDR) protein levels, may be associated with prostate cancer. As serum vitamin D levels vary by season, we sought to determine whether the expression of genes on the vitamin D pathway, assessed in prostate tumor tissue, do the same.

METHODS

Our study incorporates mRNA expression data from 362 men in the Swedish Watchful Waiting cohort, diagnosed between 1977 and 1999, and 106 men enrolled in the US Physicians' Health Study (PHS) diagnosed between 1983 and 2004. We also assayed for VDR protein expression among 832 men in the PHS and Health Professionals Follow-up Study cohorts. Season was characterized by date of initial tissue specimen collection categorically and by average monthly ultraviolet radiation levels. One-way analysis of variance was used to examine variation in the expression levels of six genes on the vitamin D pathway-VDR, GC, CYP27A1, CYP27B1, RXRα, CYP24A1-and VDR protein by season, adjusted for age at diagnosis and Gleason grade. Variation was also examined separately among lethal and nonlethal cases.

RESULTS

Tumor expression levels of the six genes did not vary significantly by season of tissue collection. No consistent patterns emerged from subgroup analyses by lethal versus nonlethal cases.

CONCLUSIONS

Unlike circulating levels of 25(OH) vitamin D, expression levels of genes on the vitamin D pathway and VDR protein did not vary overall by season of tissue collection. Epidemiological analyses of vitamin D gene expression may not be biased by seasonality.

Vitamin D receptor expression in the mucosal tissue at the gastroesophageal junction

Barrett's esophagus is considered to be a precursor to adenocarcinoma and the information on VDR expression in normal and Barrett's esophagus is significantly lacking. In this study, we examined the expression of VDR in the lower esophagus and gastric cardia of normal and Barrett's esophagus by immunofluorescence. Columnar mucosa but not squamous mucosa at the gastroesophageal junction showed positive immunofluorescence to VDR. Submucosal glands and ducts deep to the normal squamous mucosa stained positive for VDR and localized in the cytoplasm and perinuclear regions with no nuclear staining. Interestingly, Barrett's mucosa stained strongly positive for VDR. Glandular structures in the mucosal layer were far less abundant in the Barrett's mucosa than in the normal gastric mucosa. As a result, fewer structures deep to the Barrett's epithelial layer stained positive for VDR when compared to normal gastric mucosa. These findings suggest that in normal esophagus VDR expression is restricted to columnar epithelium and glandular structures. Furthermore, strong VDR expression in Barrett's mucosa may indicate an increased sensitivity of this tissue to endogenous or therapeutic effects of Vitamin D.

Characterization of vitamin D receptor (VDR) in lung adenocarcinoma

PURPOSE

The anti-proliferative effects of 1α,25-dihydroxyvitamin D(3) (1,25-D(3), calcitriol, the active form of vitamin D) are mediated by the nuclear vitamin D receptor (VDR). In the present study, we characterized VDR expression in lung adenocarcinoma (AC).

EXPERIMENTAL DESIGN

We examined VDR mRNA expression using a quantitative real-time PCR (qRT-PCR) in 100 patients who underwent surgery for lung AC. In a subset of these patients (n=89), we examined VDR protein expression using immunohistochemistry. We also examined the association of VDR protein expression with circulating serum levels of 25-hydroxyvitamin D(3) (25-D(3)) and 1,25-D(3). The antiproliferative effects and cell cycle arrest of 1,25-D(3) were examined using lung cancer cell lines with high (SKLU-1) as well as low (A549) expression of VDR mRNA.

RESULTS

Higher VDR expression correlates with longer survival after adjusting for age, sex, disease stage and tumor grade (HR 0.73, 95% CI 0.58-0.91). In addition, there was a positive correlation (r=0.38) between serum 1,25-D(3) and tumor VDR protein expression. A greater anti-proliferative effect of 1,25-D(3) was observed in high compared to low VDR-expressing cell lines; these effects corresponded to G1 cell cycle arrest; this was associated with a decline in cyclin D1, S-phase kinase protein 2 (Skp2), retinoblastoma (Rb) and minichromosome maintenance 2 (MCM2) proteins involved in S-phase entry.

CONCLUSIONS

Increased VDR expression in lung AC is associated with improved survival. This may relate to a lower proliferative status and G1 arrest in high VDR-expressing tumors.

Vitamin D receptor expression and neoadjuvant therapy in esophageal adenocarcinoma

Esophageal adenocarcinoma carries a poor prognosis. Tumor response to neoadjuvant therapy is a key prognostic factor in patients with adenocarcinoma of the esophagus, but is inconsistent. Identifying tumor characteristics that portend a favorable response to neoadjuvant therapy would be a valuable clinical tool. The anticancer actions of vitamin D and its receptor may have implications. In this study, 15 biopsy specimens were procured retrospectively from patients being treated for adenocarcinoma of the esophagus. The tissue was immunostained for the vitamin D receptor and compared on the basis of response to neoadjuvant therapy. Tumors that did not respond to neoadjuvant therapy had greater expression of VDR than tumors that responded completely. Expression of VDR declined with tumor de-differentiation. The data suggest that a relationship between vitamin D receptor expression and response to neoadjuvant therapy is plausible.

Lifestyle and dietary factors in the prevention of lethal prostate cancer

The prevention of lethal prostate cancer is a critical public health challenge that would improve health and reduce suffering from this disease. In this review, we discuss the evidence surrounding specific lifestyle and dietary factors in the prevention of lethal prostate cancer. We present a summary of evidence for the following selected behavioral risk factors: obesity and weight change, physical activity, smoking, antioxidant intake, vitamin D and calcium, and coffee intake.

Vitamin D-related genetic variation, plasma vitamin D, and risk of lethal prostate cancer: a prospective nested case-control study

BACKGROUND

The association of vitamin D status with prostate cancer is controversial; no association has been observed for overall incidence, but there is a potential link with lethal disease.

METHODS

We assessed prediagnostic 25-hydroxyvitamin D [25(OH)D] levels in plasma, variation in vitamin D-related genes, and risk of lethal prostate cancer using a prospective case-control study nested within the Health Professionals Follow-up Study. We included 1260 men who were diagnosed with prostate cancer after providing a blood sample in 1993-1995 and 1331 control subjects. Men with prostate cancer were followed through March 2011 for lethal outcomes (n = 114). We selected 97 single-nucleotide polymorphisms (SNPs) in genomic regions with high linkage disequilibrium (tagSNPs) to represent common genetic variation among seven vitamin D-related genes (CYP27A1, CYP2R1, CYP27B1, GC, CYP24A1, RXRA, and VDR). We used a logistic kernel machine test to assess whether multimarker SNP sets in seven vitamin D pathway-related genes were collectively associated with prostate cancer. Tests for statistical significance were two-sided.

RESULTS

Higher 25(OH)D levels were associated with a 57% reduction in the risk of lethal prostate cancer (highest vs lowest quartile: odds ratio = 0.43, 95% confidence interval = 0.24 to 0.76). This finding did not vary by time from blood collection to diagnosis. We found no statistically significant association of plasma 25(OH)D levels with overall prostate cancer. Pathway analyses found that the set of SNPs that included all seven genes (P = .008) as well as sets of SNPs that included VDR (P = .01) and CYP27A1 (P = .02) were associated with risk of lethal prostate cancer.

CONCLUSION

In this prospective study, plasma 25(OH)D levels and common variation among several vitamin D-related genes were associated with lethal prostate cancer risk, suggesting that vitamin D is relevant for lethal prostate cancer.

Vitamin D and cancer: a review of molecular mechanisms

The population-based association between low vitamin D status and increased cancer risk can be inconsistent, but it is now generally accepted. These relationships link low serum 25OHD (25-hydroxyvitamin D) levels to cancer, whereas cell-based studies show that the metabolite 1,25(OH)2D (1,25-dihydroxyvitamin D) is a biologically active metabolite that works through vitamin D receptor to regulate gene transcription. In the present review we discuss the literature relevant to the molecular events that may account for the beneficial impact of vitamin D on cancer prevention or treatment. These data show that although vitamin D-induced growth arrest and apoptosis of tumour cells or their non-neoplastic progenitors are plausible mechanisms, other chemoprotective mechanisms are also worthy of consideration. These alternative mechanisms include enhancing DNA repair, antioxidant protection and immunomodulation. In addition, other cell targets, such as the stromal cells, endothelial cells and cells of the immune system, may be regulated by 1,25(OH)2D and contribute to vitamin D-mediated cancer prevention.

Vitamin D metabolism and action in the prostate: implications for health and disease

Prostate cancer (PCa) is the second most common cancer in men worldwide. Epidemiological, molecular, and cellular studies have implicated vitamin D deficiency as a risk factor for the development and/or progression of PCa. Studies using cell culture systems and animal models suggest that vitamin D acts to reduce the growth of PCa through regulation of cellular proliferation and differentiation. However, although preclinical studies provide a strong indication for anti-cancer activity, proof of therapeutic benefits in men is still lacking. The anti-proliferative and pro-differentiating properties of vitamin D have been attributed to calcitriol [1,25(OH)(2)D(3)], the hormonally active form of vitamin D, acting through the vitamin D receptor (VDR). Metabolism of vitamin D in target tissues is mediated by two key enzymes: 1α-hydroxylase (CYP27B1), which catalyzes the synthesis of calcitriol from 25(OH)D and 24-hydroxylase (CYP24), which catalyzes the initial step in the conversion of calcitriol to less active metabolites. Many factors affect the balance of calcitriol synthesis and catabolism and several maneuvers, like combination therapy of calcitriol with other drugs, have been explored to treat PCa and reduce its risk. The current paper is an overview addressing some of the key factors that influence the biological actions of vitamin D and its metabolites in the treatment and/or prevention of PCa.

Watchful waiting and quality of life among prostate cancer survivors in the Physicians' Health Study

PURPOSE

We examined patient reported outcomes among patients with prostate cancer treated with watchful waiting in a nationwide cohort.

MATERIALS AND METHODS

We collected treatment information and patient reported outcomes from 1,230 patients with prostate cancer diagnosed with T1-T2 prostate cancer in the Physicians' Health Study, of whom 125 were initially treated with watchful waiting. Cox proportional hazards regression was used to identify predictors of treatment initiation among patients on watchful waiting. Logistic regression was used to calculate the OR and 95% CI to assess disease targeted quality of life by initial treatment or watchful waiting.

RESULTS

At a mean 7.3-year followup 41% of patients on watchful waiting remained free of treatment while 34% had received radiotherapy or brachytherapy, 16% had received primary hormonal therapy and 10% had undergone prostatectomy. Younger age, higher clinical stage, higher Gleason score and higher prostate specific antigen at diagnosis predicted progression to treatment. Watchful waiting compared to immediate treatment was associated with less urinary incontinence (3.5% vs 10%) and impotence (68% vs 78%) but more common obstructive urinary symptoms (22% vs 13%) on univariate analysis (each p <0.05). Incontinence and impotence differences remained significant after adjusting for age, comorbidity and time after cancer diagnosis. Quality of life outcomes in men who underwent delayed treatment after initially waiting were not worse than in men who underwent immediate treatment.

CONCLUSIONS

Findings suggest quality of life benefits after watchful waiting in select patients with early stage prostate cancer compared to men treated immediately after diagnosis. Younger age and greater cancer severity at diagnosis predicted progression to treatment.

Prediagnostic plasma vitamin D metabolites and mortality among patients with prostate cancer

BACKGROUND

Laboratory evidence suggests that vitamin D might influence prostate cancer prognosis.

METHODOLOGY/PRINCIPAL FINDINGS

We examined the associations between prediagnostic plasma levels of 25(OH)vitamin D [25(OH)D] and 1,25(OH)(2) vitamin D [1,25(OH)(2)D] and mortality among 1822 participants of the Health Professionals Follow-up Study and Physicians' Health Study who were diagnosed with prostate cancer. Cox proportional hazards models were used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) of total mortality (n = 595) and lethal prostate cancer (death from prostate cancer or development of bone metastases; n = 202). In models adjusted for age at diagnosis, BMI, physical activity, and smoking, we observed a HR of 1.22 (95% CI: 0.97, 1.54) for total mortality, comparing men in the lowest to the highest quartile of 25(OH)D. There was no association between 1,25(OH)(2)D and total mortality. Men with the lowest 25(OH)D quartile were more likely to die of their cancer (HR: 1.59; 95% CI: 1.06, 2.39) compared to those in the highest quartile (P(trend) = 0.006). This association was largely explained by the association between low 25(OH)D levels and advanced cancer stage and higher Gleason score, suggesting that these variables may mediate the influence of 25(OH)D on prognosis. The association also tended to be stronger among patients with samples collected within five years of cancer diagnosis. 1,25(OH)(2)D levels were not associated with lethal prostate cancer.

CONCLUSIONS/SIGNIFICANCE

Although potential bias of less advanced disease due to more screening activity among men with high 25(OH)D levels cannot be ruled out, higher prediagnostic plasma 25(OH)D might be associated with improved prostate cancer prognosis.