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

Discordant Health Implications and Molecular Mechanisms of Vitamin D in Clinical and Preclinical Studies of Prostate Cancer: A Critical Appraisal of the Literature Data

Clinical and preclinical studies have provided conflicting data on the postulated beneficial effects of vitamin D in patients with prostate cancer. In this opinion piece, we discuss reasons for discrepancies between preclinical and clinical vitamin D studies. Different criteria have been used as evidence for the key roles of vitamin D. Clinical studies report integrative cancer outcome criteria such as incidence and mortality in relation to vitamin D status over time. In contrast, preclinical vitamin D studies report molecular and cellular changes resulting from treatment with the biologically active vitamin D metabolite, 1,25-dihydroxyvitamin D3 (calcitriol) in tissues. However, these reported changes in preclinical in vitro studies are often the result of treatment with biologically irrelevant high calcitriol concentrations. In typical experiments, the used calcitriol concentrations exceed the calcitriol concentrations in normal and malignant prostate tissue by 100 to 1000 times. This raises reasonable concerns regarding the postulated biological effects and mechanisms of these preclinical vitamin D approaches in relation to clinical relevance. This is not restricted to prostate cancer, as detailed data regarding the tissue-specific concentrations of vitamin D metabolites are currently lacking. The application of unnaturally high concentrations of calcitriol in preclinical studies appears to be a major reason why the results of preclinical in vitro studies hardly match up with outcomes of vitamin D-related clinical studies. Regarding future studies addressing these concerns, we suggest establishing reference ranges of tissue-specific vitamin D metabolites within various cancer entities, carrying out model studies on human cancer cells and patient-derived organoids with biologically relevant calcitriol concentrations, and lastly improving the design of vitamin D clinical trials where results from preclinical studies guide the protocols and endpoints within these trials.

Emerging perspectives: unraveling the anticancer potential of vitamin D3

Vitamin D3, a fat-soluble vitamin known for its critical function in calcium homeostasis and bone health, is gaining interest for its anticancer properties. Observational studies have suggested a negative relationship between vitamin D levels and the incidence of some malignancies throughout the years, prompting substantial investigation to find its anticancer effects. The purpose of this comprehensive review is to investigate the diverse function of vitamin D3 in cancer prevention and therapy. We explored the molecular mechanism underlying its effects on cancer cells, which range from cell cycle control and death to angiogenesis and immune response modulation. Insights from in vitro and in vivo studies provide valuable evidence supporting its anticancer potential. Furthermore, we look at epidemiological and clinical studies that investigate the relationship between vitamin D3 levels and cancer risk or treatment results. Vitamin D3 supplementation's safety profile and cost-effectiveness increase its attractiveness as an adjuvant therapy in conjunction with traditional treatment regimens. Our critical review of the current literature provides an in-depth understanding of vitamin D3's anticancer effect, covering the obstacles and possibilities in realizing its promise for cancer prevention and therapy. The findings of this study might pave the way for the development of innovative treatment techniques that take use of the advantages of vitamin D3 to fight cancer and improve patient care. As research progresses, a better understanding of vitamin D3's anticancer processes will surely simplify its incorporation into personalized cancer care techniques, hence enhancing patient outcomes in the battle against cancer.

Cancer Metabolism as a Therapeutic Target and Review of Interventions

Cancer is amenable to low-cost treatments, given that it has a significant metabolic component, which can be affected through diet and lifestyle change at minimal cost. The Warburg hypothesis states that cancer cells have an altered cell metabolism towards anaerobic glycolysis. Given this metabolic reprogramming in cancer cells, it is possible to target cancers metabolically by depriving them of glucose. In addition to dietary and lifestyle modifications which work on tumors metabolically, there are a panoply of nutritional supplements and repurposed drugs associated with cancer prevention and better treatment outcomes. These interventions and their evidentiary basis are covered in the latter half of this review to guide future cancer treatment.

Impact of Vitamin D Deficiency on Tumor Aggressiveness in Neuroendocrine Neoplasms

Background: The role of vitamin D (25(OH)D) in the pathogenesis and outcome of several conditions, including autoimmune diseases, diabetes and cancers is largely described in the literature. The aims of this study were to evaluate the prevalence of 25(OH)D deficit in a cohort of patients with neuroendocrine neoplasms (NENs) in comparison to a matched healthy control group and to analyze the possible role of 25(OH)D as a prognostic factor for NENs in terms of biological aggressiveness, tumor progression and survival. Methods: From 2009 to 2023, 172 patients with NENs (99 females; median age, 63 years) were included in the study. Serum 25(OH)D levels were defined as deficient if ≤20 ng/mL. The possible associations between 25(OH)D levels and disease grading, staging, ki67%, overall survival (OS), and progression-free survival (PFS) were considered. Results: NEN patients had significantly lower 25(OH)D levels compared to controls (p < 0.001) regardless of the primary origin. Patients with 25(OH)D < 20 ng/mL had a significantly higher ki67 index (p = 0.02) compared to the ones with 25(OH)D levels above 20 ng/mL. Patients with disease progression were found to have a significantly lower 25(OH)D at baseline (p = 0.02), whereas PFS and OS were not significantly influenced by 25(OH)D. Conclusions: Vitamin D deficiency is highly prevalent among NENs and is associated with higher ki67 and disease progression. Our study highlights the importance of monitoring 25(OH)D levels in patients with NENs, as its deficiency appeared to be linked to the worst biological tumor aggressiveness.

Does testosterone mediate the relationship between vitamin D and prostate cancer progression? A systematic review and meta-analysis

PURPOSE

Observational studies and randomized controlled trials (RCTs) have shown an association between vitamin D levels and prostate cancer progression. However, evidence of direct causality is sparse and studies have not examined biological mechanisms, which can provide information on plausibility and strengthen the evidence for causality.

METHODS

We used the World Cancer Research Fund International/University of Bristol two-stage framework for mechanistic systematic reviews. In stage one, both text mining of published literature and expert opinion identified testosterone as a plausible biological mechanism. In stage two, we performed a systematic review and meta-analysis to assess the evidence from both human and animal studies examining the effect of vitamin D on testosterone, and testosterone on advanced prostate cancer (diagnostic Gleason score of ≥ 8, development of metastasis) or prostate cancer-specific mortality.

RESULTS

A meta-analysis of ten human RCTs showed evidence of an effect of vitamin D on total testosterone (standardised mean difference (SMD) = 0.133, 95% CI =  - 0.003-0.269, I2 = 0.0%, p = 0.056). Five human RCTs showed evidence of an effect of vitamin D on free testosterone (SMD = 0.173, 95% CI =  - 0.104-0.450, I2 = 52.4%, p = 0.220). Three human cohort studies of testosterone on advanced prostate cancer or prostate cancer-specific mortality provided inconsistent results. In one study, higher levels of calculated free testosterone were positively associated with advanced prostate cancer or prostate cancer-specific mortality. In contrast, higher levels of dihydrotestosterone were associated with lowering prostate cancer-specific mortality in another study. No animal studies met the study eligibility criteria.

CONCLUSION

There is some evidence that vitamin D increases levels of total and free testosterone, although the effect of testosterone levels within the normal range on prostate cancer progression is unclear. The role of testosterone as a mechanism between vitamin D and prostate cancer progression remains inconclusive.

Vitamin D Metabolites in Nonmetastatic High-Risk Prostate Cancer Patients with and without Zoledronic Acid Treatment after Prostatectomy

Simple Summary

Recent research on prostate cancer and vitamin D is controversial. We measured three vitamin D₃ metabolites in 32 selected prostate cancer patients after surgery at four time points over four years. Within a large European study, half of the patients were prophylactically treated with zoledronic acid (ZA); the others received a placebo. After the study start, all the patients daily took calcium and vitamin D₃. The development of metastasis was not affected by ZA treatment. While two vitamin D metabolites had higher values after the study’s start, with constant follow-up values, the 1,25(OH)₂-vitamin D₃ concentrations remained unchanged. The latter form was the only metabolite that was higher in the patients with metastasis as compared to those without bone metastasis. This result is surprising. However, it is too premature to discuss possible prognostic value yet. Our results should be confirmed in larger cohorts.

Abstract

There are limited and discrepant data on prostate cancer (PCa) and vitamin D. We investigated changes in three vitamin D₃ metabolites in PCa patients after prostatectomy with zoledronic acid (ZA) treatment regarding their metastasis statuses over four years. In 32 patients from the ZEUS trial, 25(OH)D₃, 24,25(OH)₂D₃, and 1,25(OH)₂D₃ were measured with liquid chromatography coupled with tandem mass spectrometry at four time points. All the patients received daily calcium and vitamin D₃. Bone metastases were detected in 7 of the 17 ZA-treated patients and in 5 of the 15 controls (without ZA), without differences between the groups (p = 0.725). While 25(OH)D₃ and 24,25(OH)₂D₃ increased significantly after the study’s start, with following constant values, the 1,25(OH)₂D₃ concentrations remained unchanged. ZA treatment did not change the levels of the three metabolites. 25(OH)D₃ and 24,25(OH)₂D₃ were not associated with the development of bone metastases. In contrast, 1,25(OH)₂D₃ was also higher in patients with bone metastasis before the study’s start. Thus, in high-risk PCa patients after prostatectomy, 25(OH)D₃, 24,25(OH)₂D₃, and 1,25(OH)₂D₃ were not affected by supportive ZA treatment or by the development of metastasis over four years, with the exception of 1,25(OH)₂D₃, which was constantly higher in metastatic patients. There might be potential prognostic value if the results can be confirmed.

Altered expression of the vitamin D metabolizing enzymes CYP27B1 and CYP24A1 under the context of prostate aging and pathologies

Low circulating levels of vitamin D are common at older ages and have been linked to an increased risk of prostate disease, including cancer. However, it has not yet been determined whether aging affects the ability of prostate cells to locally metabolize vitamin D into its active metabolite calcitriol and thus mediate the vitamin D signaling in autocrine and paracrine ways. By using a suitable rat model to interrogate spontaneous prostatic modifications over the course of aging, here we showed that both CYP27B1 and CYP24A1 enzymes, which are key players respectively involved with calcitriol synthesis and deactivation, were highly expressed in the prostate epithelium. Furthermore, as the animals aged, a drastic reduction of CYP27B1 levels was detected in total protein extracts and especially in epithelial areas of lesions, including tumors. On the other hand, CYP24A1 expression significantly increased with aging and remained elevated even in altered epithelia. Such intricate unbalance in regard to vitamin D metabolizing enzymes was strongly associated with reduced bioavailability of calcitriol in the senile prostate, which in addition to decreased expression of the vitamin D receptor, further limits the protective actions mediated by vitamin D signaling. This evidence was corroborated by the increased proliferative activity exactly at sites of lesions where the factors implicated with calcitriol synthesis and responsiveness had its expression inhibited. Taken together, our results emphasize a set of modifications over the course of aging with a high potential to hamper vitamin D signaling on the prostate. These findings highlight a crosstalk between vitamin D, aging, and prostate carcinogenesis, offering new potential targets in the prevention of malignancies and other aging-related disorders arising in the gland.

High-dose vitamin D supplementation to prevent prostate cancer progression in localised cases with low-to-intermediate risk of progression on active surveillance (ProsD): protocol of a phase II randomised controlled trial

INTRODUCTION

Active surveillance (AS) for patients with prostate cancer (PC) with low risk of PC death is an alternative to radical treatment. A major drawback of AS is the uncertainty whether a patient truly has low risk PC based on biopsy alone. Multiparametric MRI scan together with biopsy, appears useful in separating patients who need curative therapy from those for whom AS may be safe. Two small clinical trials have shown short-term high-dose vitamin D supplementation may prevent PC progression. There is no substantial evidence for its long-term safety and efficacy, hence its use in the care of men with PC on AS needs assessment. This protocol describes the ProsD clinical trial which aims to determine if oral high-dose vitamin D supplementation taken monthly for 2 years can prevent PC progression in cases with low-to-intermediate risk of progression.

METHOD AND ANALYSIS

This is an Australian national multicentre, 2:1 double-blinded placebo-controlled phase II randomised controlled trial of monthly oral high-dose vitamin D supplementation (50 000 IU cholecalciferol), in men diagnosed with localised PC who have low-to-intermediate risk of disease progression and are being managed by AS. This trial will assess the feasibility, efficacy and safety of supplementing men with an initial oral loading dose of 500 000 IU cholecalciferol, followed by a monthly oral dose of 50 000 IU during the 24 months of AS. The primary trial outcome is the commencement of active therapy for clinical or non-clinical reason, within 2 years of AS.

ETHICS AND DISSEMINATION

This trial is approved by Bellberry Ethics Committee (2016-06-459). All results will be reported in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ACTRN12616001707459.

Pharmacokinetic Estimation Models-based Approach to Predict Clinical Implications for CYP Induction by Calcitriol in Human Cryopreserved Hepatocytes and HepaRG Cells

Calcitriol, a vitamin D₃ metabolite, is approved for various indications because it is the bioactive form of vitamin D in the body. The purpose of this study was to predict the clinical significance of cytochrome P450 (CYP) induction by calcitriol using in vitro human cryopreserved hepatocytes, HepaRG experimental systems, and various pharmacokinetic estimation models. CYP2B6, 3A4, 2C8, and 2C9 mRNA levels increased in a concentration-dependent manner in the presence of calcitriol in human cryopreserved hepatocytes and HepaRG cells. Using the half maximal effective concentration (EC₅₀) and maximum induction effect (E_max) obtained from the in vitro study, a basic kinetic model was applied, suggesting clinical relevance. In addition, a static mechanistic model showed the improbability of a clinically significant effect; however, the calculated area under the plasma concentration-time curve ratio (AUCR) was marginal for CYP3A4 in HepaRG cells. To clarify the effect of CYP3A4 in vivo, physiologically based pharmacokinetic (PBPK) modeling was applied as a dynamic mechanistic model, revealing a low clinically significant effect of CYP3A4 induction by calcitriol. Therefore, we conclude that CYP induction by calcitriol treatment would not be clinically significant under typical clinical conditions.

Vitamin D sufficiency enhances differentiation of patient-derived prostate epithelial organoids

Vitamin D is an essential steroid hormone that regulates systemic calcium homeostasis and cell fate decisions. The prostate gland is hormonally regulated, requiring steroids for proliferation and differentiation of secretory luminal cells. Vitamin D deficiency is associated with an increased risk of lethal prostate cancer, which exhibits a dedifferentiated pathology, linking vitamin D sufficiency to epithelial differentiation. To determine vitamin D regulation of prostatic epithelial differentiation, patient-derived benign prostate epithelial organoids were grown in vitamin D-deficient or -sufficient conditions. Organoids were assessed by phenotype and single-cell RNA sequencing. Mechanistic validation demonstrated that vitamin D sufficiency promoted organoid growth and accelerated differentiation by inhibiting canonical Wnt activity and suppressing Wnt family member DKK3. Wnt and DKK3 were also reduced by vitamin D in prostate tissue explants by spatial transcriptomics. Wnt dysregulation is a known contributor to aggressive prostate cancer, thus findings further link vitamin D deficiency to lethal disease.

Dietary Factors and Supplements Influencing Prostate Specific-Antigen (PSA) Concentrations in Men with Prostate Cancer and Increased Cancer Risk: An Evidence Analysis Review Based on Randomized Controlled Trials

The quest for dietary patterns and supplements efficient in down-regulating prostate-specific antigen (PSA) concentrations among men with prostate cancer (PCa) or increased PCa risk has been long. Several antioxidants, including lycopene, selenium, curcumin, coenzyme Q10, phytoestrogens (including isoflavones and flavonoids), green tea catechins, cernitin, vitamins (C, E, D) and multivitamins, medicinal mushrooms (Ganoderma lucidum), fruit extracts (saw palmetto, cranberries, pomegranate), walnuts and fatty acids, as well as combined supplementations of all, have been examined in randomized controlled trials (RCTs) in humans, on the primary, secondary, and tertiary PCa prevention level. Despite the plethora of trials and the variety of examined interventions, the evidence supporting the efficacy of most dietary factors appears inadequate to recommend their use.

Vitamin D Signaling in Inflammation and Cancer: Molecular Mechanisms and Therapeutic Implications

Vitamin D and its active metabolites are important nutrients for human skeletal health. UV irradiation of skin converts 7-dehydrocholesterol into vitamin D3, which metabolized in the liver and kidneys into its active form, 1α,25-dihydroxyvitamin D3. Apart from its classical role in calcium and phosphate regulation, scientists have shown that the vitamin D receptor is expressed in almost all tissues of the body, hence it has numerous biological effects. These includes fetal and adult homeostatic functions in development and differentiation of metabolic, epidermal, endocrine, neurological and immunological systems of the body. Moreover, the expression of vitamin D receptor in the majority of immune cells and the ability of these cells to actively metabolize 25(OH)D3 into its active form 1,25(OH)₂D3 reinforces the important role of vitamin D signaling in maintaining a healthy immune system. In addition, several studies have showed that vitamin D has important regulatory roles of mechanisms controlling proliferation, differentiation and growth. The administration of vitamin D analogues or the active metabolite of vitamin D activates apoptotic pathways, has antiproliferative effects and inhibits angiogenesis. This review aims to provide an up-to-date overview on the effects of vitamin D and its receptor (VDR) in regulating inflammation, different cell death modalities and cancer. It also aims to investigate the possible therapeutic benefits of vitamin D and its analogues as anticancer agents.

Safety of dietary supplements use among patients with cancer: A systematic review

Dietary supplements (DS) are commonly taken by patients with cancer, but safety of DS use remains unclear. A systematic literature search was conducted using PubMed, ClinicalTrials.gov, International Pharmaceutical Abstracts and Alt HealthWatch databases from inception through October 12, 2018. Included studies were limited to clinical trials including patients with cancer, DS products as interventions, evaluation of safety endpoints of DS use, and published in English. Sixty-five studies were included to evaluate 20 different DS among patients with 12 types of cancer. Botanical DS (n = 13), vitamins (n = 8), and probiotics/synbiotics (n = 7) were the top 3 types of DS evaluated in these trials. Majority of studied DS appeared safe. Among 19 trials including patients with cancer undergoing chemotherapy, most (n = 18) of studied DS (e.g., vitamins, botanical, omega-3 fatty acid) were found to be safe. Evaluation of DS use and its safety should be regularly incorporated in clinical trials among patients with cancer.

Vitamin D-Induced Molecular Mechanisms to Potentiate Cancer Therapy and to Reverse Drug-Resistance in Cancer Cells

Increasing interest in studying the role of vitamin D in cancer has been provided by the scientific literature during the last years, although mixed results have been reported. Vitamin D deficiency has been largely associated with various types of solid and non-solid human cancers, and the almost ubiquitous expression of vitamin D receptor (VDR) has always led to suppose a crucial role of vitamin D in cancer. However, the association between vitamin D levels and the risk of solid cancers, such as colorectal, prostate and breast cancer, shows several conflicting results that raise questions about the use of vitamin D supplements in cancer patients. Moreover, studies on vitamin D supplementation do not always show improvements in tumor progression and mortality risk, particularly for prostate and breast cancer. Conversely, several molecular studies are in agreement about the role of vitamin D in inhibiting tumor cell proliferation, growth and invasiveness, cell cycle arrest and inflammatory signaling, through which vitamin D may also regulate cancer microenvironment through the activation of different molecular pathways. More recently, a role in the regulation of cancer stem cells proliferation and short non-coding microRNA (miRNAs) expression has emerged, conferring to vitamin D a more crucial role in cancer development and progression. Interestingly, it has been shown that vitamin D is able not only to potentiate the effects of traditional cancer therapy but can even contribute to overcome the molecular mechanisms of drug resistance—often triggering tumor-spreading. At this regard, vitamin D can act at various levels through the regulation of growth of cancer stem cells and the epithelial–mesenchymal transition (EMT), as well as through the modulation of miRNA gene expression. The current review reconsiders epidemiological and molecular literature concerning the role of vitamin D in cancer risk and tumor development and progression, as well as the action of vitamin D supplementation in potentiating the effects of drug therapy and overcoming the mechanisms of resistance often triggered during cancer therapies, by critically addressing strengths and weaknesses of available data from 2010 to 2020.

Post-treatment levels of plasma 25- and 1,25-dihydroxy vitamin D and mortality in men with aggressive prostate cancer

Vitamin D may reduce mortality from prostate cancer (PC). We examined the associations of post-treatment plasma 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D concentrations with PC mortality. Participants were PC cases from the New South Wales Prostate Cancer Care. All contactable and consenting participants, at 4.9 to 8.6 years after diagnosis, were interviewed and had plasma 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)₂D) measured in blood specimens. Cox regression allowing for left-truncation was used to calculate adjusted mortality hazards ratios (HR) and 95% confidence intervals (95% CI) for all-cause and PC-specific mortality in relation to vitamin D levels and other potentially-predictive variables. Of the participants (n = 111; 75·9% response rate), there were 198 deaths from any cause and 41 from PC in the study period. Plasma 25(OH)D was not associated with all-cause or PC-specific mortality (p-values > 0·10). Plasma 1,25(OH)₂D was inversely associated with all-cause mortality (HR for highest relative to lowest quartile = 0·45; 95% CI: 0·29-0·69), and PC-specific mortality (HR = 0·40; 95% CI: 0·14-1·19). These associations were apparent only in men with aggressive PC: all-cause mortality HR = 0·28 (95% CI·0·15-0·52; p-interaction = 0·07) and PC-specific mortality HR = 0·26 (95% CI: 0·07-1.00). Time spent outdoors was also associated with lower all-cause (HR for 4^th relative to 1^st exposure quartile = 0·42; 95% CI: 0·24-0·75) and PC-specific (HR = 0·48; 95% CI: 0·14-1·64) mortality, although the 95% CI for the latter was wide. The inverse association between post-treatment plasma 1,25(OH)₂D levels and all-cause and PC-specific mortality in men with aggressive PC, suggest a possible beneficial effect of vitamin D supplementation in these men.

Single Nucleotide Polymorphisms in 25-Hydroxyvitamin D3 1-Alpha-Hydroxylase (CYP27B1) Gene: The Risk of Malignant Tumors and Other Chronic Diseases

: Vitamin D is widely known for its roles in the promotion of apoptosis and differentiation, with simultaneous inhibition of proliferation, inflammation, angiogenesis, invasion, and metastasis. Modern literature lacks complete information on polymorphisms in CYP27B1, the only enzyme capable of vitamin D activation. This review presents gathered data that relate to genetic variants in CYP27B1 gene in correlation to multiple diseases, mostly concerning colorectal, prostate, breast, lung, and pancreatic cancers, as well as on other pathologies, such as non-Hodgkin's lymphoma, oral lichen planus, or multiple sclerosis.

No association of serum PSA with vitamin D or total oxidant-antioxidant capacity in healthy men

Background and aim: Vitamin D deficiency and oxidative stress were suggested to be related to prostate cancer risk. We aimed to investigate the association of serum PSA concentration with vitamin D and total oxidant/antioxidant levels. Materials and methods: A total of 95 healthy men were enrolled for the cross sectional study. Serum PSA, 25(OH)D, serum total oxidant status, and total antioxidant status were measured. Results: Serum PSA was significantly negatively correlated with serum total oxidant status (r= -0.309, p = .003) but there was no significant correlation between PSA and 25(OH)D (p = .383) or total antioxidant levels (p = .233). After adjustment for age BMI and smoking status with multiple regression analysis, there was no significant association between serum PSA and total oxidant status. Conclusion: We find no evidence for an association between PSA and vitamin D levels or serum total oxidant/antioxidant levels.

Association among plasma 1,25(OH)2 D, ratio of 1,25(OH)2 D to 25(OH)D, and prostate cancer aggressiveness

BACKGROUND

African-American (AA) men tend to present with more aggressive prostate cancer (Gleason score >7) than European-American (EA) men. Vitamin D and its metabolites are implicated in prostate cancer biology with vitamin D deficiency, indicated by its metabolite levels in serum or plasma, usually observed in AA men.

OBJECTIVE

To determine if 1, 25-dihydroxy vitamin D3 [1,25(OH)2 D] plasma levels in AA and EA prostate cancer patients alter the risk of having aggressive prostate cancer.

DESIGN

Research subjects from the North Carolina-Louisiana Prostate Cancer Project (AA n = 435 and EA n = 532) were included. Plasma metabolites 1,25(OH)2 D and 25-hydroxyvitamin D3 [25(OH)D] were measured using liquid chromatography with tandem mass spectrophotometry. Research subjects were classified into low (Gleason sum < 7, stage T1-T2, and Prostate-specific antigen (PSA) < 9 ng/mL) or high (Gleason sum > 8 or Gleason sum = 7 with 4 + 3, or PSA > 20 ng/mL, or Gleason sum = 7 and stage T3-T4) aggressive disease.

RESULTS

Research subjects in the second and third tertiles of plasma levels of 1, 25(OH)2 D had lower odds of high aggressive prostate cancer (AA [ORT2vsT1 : 0.66, 95%CI: 0.39-1.12; ORT3vsT1 : 0.83, 95%CI: 0.49-1.41] and EA [ORT2vsT1 : 0.68, 95%CI: 0.41-1.11; ORT3vsT1 : 0.67, 95%CI: 0.40-1.11]) compared with the first tertile, though confidence intervals included the null. Greater 1,25(OH)2 D/25(OH)D molar ratios were associated with lower odds of high aggressive prostate cancer more evidently in AA (ORQ4vsQ1 : 0.45, CI: 0.24-0.82) than in EA (ORQ4vsQ1 : 0.64, CI: 0.35-1.17) research subjects.

CONCLUSIONS

The 1,25(OH)2 D/25(OH)D molar ratio was associated with decreased risk of high aggressive prostate cancer in AA men, and possibly in EA men. Further studies analyzing vitamin D polymorphisms, vitamin D binding protein levels, and prostatic levels of these metabolites may be useful. These studies may provide a better understanding of the vitamin D pathway and its biological role underlying health disparities in prostate cancer.

Vitamin D in prostate cancer

Signaling through the vitamin D receptor has been shown to be biologically active and important in a number of preclinical studies in prostate and other cancers. Epidemiologic data also indicate that vitamin D signaling may be important in the cause and prognosis of prostate and other cancers. These data indicate that perturbation of vitamin D signaling may be a target for the prevention and treatment of prostate cancer. Large studies of vitamin D supplementation will be required to determine whether these observations can be translated into prevention strategies. This paper reviews the available data in the use of vitamin D compounds in the treatment of prostate cancer. Clinical data are limited which support the use of vitamin D compounds in the management of men with prostate cancer. However, clinical trials guided by existing preclinical data are limited.

High levels of PIWI-interacting RNAs are present in the small RNA landscape of prostate epithelium from vitamin D clinical trial specimens

BACKGROUND

Vitamin D, a hormone that acts through the nuclear vitamin D receptor (VDR), upregulates antitumorigenic microRNA in prostate epithelium. This may contribute to the lower levels of aggressive prostate cancer (PCa) observed in patients with high serum vitamin D. The small noncoding RNA (ncRNA) landscape includes many other RNA species that remain uncharacterized in prostate epithelium and their potential regulation by vitamin D is unknown.

METHODS

Laser capture microdissection (LCM) followed by small-RNA sequencing was used to identify ncRNAs in the prostate epithelium of tissues from a vitamin D-supplementation trial. VDR chromatin immunoprecipitation-sequencing was performed to identify vitamin D genomic targets in primary prostate epithelial cells.

RESULTS

Isolation of epithelium by LCM increased sample homogeneity and captured more diversity in ncRNA species compared with publicly available small-RNA sequencing data from benign whole prostate. An abundance of PIWI-interacting RNAs (piRNAs) was detected in normal prostate epithelium. The obligate binding partners of piRNAs, PIWI-like (PIWIL) proteins, were also detected in prostate epithelium. High prostatic vitamin D levels were associated with increased expression of piRNAs. VDR binding sites were located near several ncRNA biogenesis genes and genes regulating translation and differentiation.

CONCLUSIONS

Benign prostate epithelium expresses both piRNA and PIWIL proteins, suggesting that these small ncRNA may serve an unknown function in the prostate. Vitamin D may increase the expression of prostatic piRNAs. VDR binding sites in primary prostate epithelial cells are consistent with its reported antitumorigenic functions and a role in ncRNA biogenesis.

Effect of Vitamin D Supplementation in Prostate Cancer: A Systematic Review of Randomized Control Trials

Vitamin D is important in many cellular functions including cell cycling and proliferation, differentiation, and apoptosis. Via the induction of cell cycle arrest and/or apoptosis, vitamin D inhibits normal prostatic epithelial cells growth. Review the evidence of the effect of vitamin D supplementation on prostate cancer (PC) biomarkers and patient survival and assess optimal dosage, formulation and duration. Pubmed, Medline and Ebsco Host databases were systematically searched for relevant literature. 8 Randomized Controlled Trials were included in this review. All studies, besides one, were of high methodological quality. 4 studies used calcitriol (0,5-45 μg/weekly), 2 studies have used vitamin D3 (150-1000 μg/daily) and 2 other studies have used 1α-hydroxy Vitamin D2 (10 μg/ daily or weekly). Duration of supplementation varied between 28 days up to 18.3 months. Two studies had positive effects on prostate specific antigen (PSA) (p < .05), 1 study had a significant positive effect on median survival (p < .05) and 1 study showed a significant reduction of vitamin D receptor (VDR) expression (p < .05). The remaining studies showed negative or no effect on PC characteristics, clinical outcomes and/or survival. Current evidence suggests that vitamin D supplementation in conjunction with standard of care (e.g. chemotherapy, radiation therapy) may confer clinical benefits such as a decrease in serum PSA levels and VDR expression but further research is required to ascertain these results. Calcitriol supplementation in doses ranging from 250-1000 mg for 3-8 weeks or a lower dose of 45 mg for 18.3 months, appear most beneficial regarding outcomes of PC progression and survival.

Vitamin D Signaling Suppresses Early Prostate Carcinogenesis in TgAPT121 Mice

We tested whether lifelong modification of vitamin D signaling can alter the progression of early prostate carcinogenesis in studies using mice that develop high-grade prostatic intraepithelial neoplasia that is similar to humans. Two tissue-limited models showed that prostate vitamin D receptor (VDR) loss increased prostate carcinogenesis. In another study, we fed diets with three vitamin D₃ levels (inadequate = 25 IU/kg diet, adequate for bone health = 150 IU/kg, or high = 1,000 IU/kg) and two calcium levels (adequate for bone health = 0.5% and high = 1.5%). Dietary vitamin D caused a dose-dependent increase in serum 25-hydroxyvitamin D levels and a reduction in the percentage of mice with adenocarcinoma but did not improve bone mass. In contrast, high calcium suppressed serum 1,25-dihydroxyvitamin D levels and improved bone mass but increased the incidence of adenocarcinoma. Analysis of the VDR cistrome in RWPE1 prostate epithelial cells revealed vitamin D-mediated regulation of multiple cancer-relevant pathways. Our data support the hypothesis that the loss of vitamin D signaling accelerates the early stages of prostate carcinogenesis, and our results suggest that different dietary requirements may be needed to support prostate health or maximize bone mass. SIGNIFICANCE: This work shows that disrupting vitamin D signaling through diet or genetic deletion increases early prostate carcinogenesis through multiple pathways. Higher-diet vitamin D levels are needed for cancer than bone.

Vitamin D and Atherosclerotic Cardiovascular Disease

CONTEXT

A large body of experimental and observational data has implicated vitamin D deficiency in the development of cardiovascular disease. However, evidence to support routine vitamin D supplementation to prevent or treat cardiovascular disease is lacking.

EVIDENCE ACQUISITION

A comprehensive literature review was performed using Pubmed and other literature search engines.

EVIDENCE SYNTHESIS

Mounting epidemiological evidence and data from Mendelian randomization studies support a link between vitamin D deficiency and adverse cardiovascular health outcomes, but randomized trial evidence to support vitamin D supplementation is sparse. Current public health guidelines restrict vitamin D intake recommendations to the maintenance of bone health and prevention of fractures. Two recently published large trials (VITAL and ViDA) that assessed the role of moderate-to-high dose vitamin D supplementation as primary prevention for cardiovascular outcomes in the general population had null results, and previous randomized trials have also been generally negative. These findings from general population cohorts that are largely replete in vitamin D may not be applicable to chronic kidney disease (CKD) populations, in which the use of active (1α-hydroxylated) vitamin D compounds is prevalent, or to other high-risk populations. Additionally, recent trials in the CKD population, and trials using vitamin D analogues have been limited.

CONCLUSIONS

Current randomized trials of vitamin D supplementation do not support benefits for cardiovascular health, but the evidence remains inconclusive. Additional randomized trials assessing larger numbers of participants with low baseline vitamin D levels, having longer follow-up periods, and testing higher vitamin D dosages, are needed to guide clinical practice.

Repurposing vitamin D for treatment of human malignancies via targeting tumor microenvironment

Tumor cells along with a small proportion of cancer stem cells exist in a stromal microenvironment consisting of vasculature, cancer-associated fibroblasts, immune cells and extracellular components. Recent epidemiological and clinical studies strongly support that vitamin D supplementation is associated with reduced cancer risk and favorable prognosis. Experimental results suggest that vitamin D not only suppresses cancer cells, but also regulates tumor microenvironment to facilitate tumor repression. In this review, we have outlined the current knowledge on epidemiological studies and clinical trials of vitamin D. Notably, we summarized and discussed the anticancer action of vitamin D in cancer cells, cancer stem cells and stroma cells in tumor microenvironment, providing a better understanding of the role of vitamin D in cancer. We presently re-propose vitamin D to be a novel and economical anticancer agent.

Does testosterone mediate the relationship between vitamin D and prostate cancer? A systematic review and meta-analysis protocol

BACKGROUND

Evidence from studies on prostate cancer progression have identified vitamin D to be a potentially important nutrient. However, the World Cancer Research Fund and American Institute for Cancer Research have reported the quality of this evidence to be limited and warrant further investigation. We plan to use the recently developed WCRF International/University of Bristol mechanistic systematic review framework to determine whether the observed association between vitamin D and prostate cancer exists through a plausible biological pathway.

METHODS

This protocol sets out how we will perform a systematic review of the literature in human and animal studies. We will search the electronic databases MEDLINE, EMBASE, PubMed, and BIOSIS Citation Index without restrictions on year of publication or language. We will extract data from observational and experimental studies examining two inter-linked pathways in the relationship between vitamin D and prostate cancer progression: (1) vitamin D and testosterone, and (2) testosterone and prostate cancer progression. We focus on testosterone as its actions form a potentially novel intermediate mechanism that was identified via our online literature mining tools. The outcomes of interest include incidence or prevalence of prostate cancer, measures of prostate cancer progression (including biochemical recurrence, local, or distal metastases), and prostate cancer-specific mortality. We will assess study quality and the level of certainty of the evidence. We will analyse data where possible, using meta-analysis with forest plots or albatross plots; otherwise, a narrative synthesis will be performed.

DISCUSSION

To our knowledge, this will be the first systematic synthesis of the evidence underpinning the vitamin D-testosterone-prostate cancer mechanistic pathway. The results of the review may inform future research, intervention trials, and public health messages.

Physiologic serum 1,25 dihydroxyvitamin D is inversely associated with prostatic Ki67 staining in a diverse sample of radical prostatectomy patients

PURPOSE

To investigate the correlation between serum 25 hydroxyvitamin D, prostatic 25 hydroxyvitamin D, and serum 1,25 dihydroxyvitamin D, and their respective associations with prostatic tumor proliferation at the time of radical prostatectomy.

METHODS

In this cross-sectional analysis of 119 men undergoing radical prostatectomy, serum from whole blood and expressed prostatic fluid was collected on the day of surgery. Tumor proliferation was measured in the dominant tumor on formalin-fixed prostatectomy tissues by immunohistochemical staining for Ki67 and quantified by Aperio imaging analysis.

RESULTS

The sample included 88 African Americans (74%) and 31 (26%) European Americans. Serum and prostatic levels of 25 hydroxyvitamin D were correlated with each other (Spearman's rho (ρ) = 0.27, p = 0.004), and there was also a correlation between serum 25 hydroxyvitamin D and 1,25 dihydroxyvitamin D (ρ = 0.34, p < 0.001). Serum and prostatic 25 hydroxyvitamin D levels were not correlated with Ki67 staining in tumor cells. Serum 1,25 dihydroxyvitamin D was inversely correlated with Ki67 staining in tumor cells (ρ = - 0.30, p = 0.002). On linear regression, serum 1,25 dihydroxyvitamin D was negatively associated with Ki67 staining in tumor cells (β - 0.46, 95% CI - 0.75, - 0.04, p = 0.04).

CONCLUSION

The correlation between physiologic serum levels of 25 hydroxyvitamin D with both prostatic 25 hydroxyvitamin D and serum 1,25 dihydroxyvitamin D suggests that serum levels are reasonable biomarkers of vitamin D status. Furthermore, serum 1,25 dihydroxyvitamin D has an inverse association with Ki67 staining in tumor cells at physiologic levels and may protect against tumor progression.

Circulating vitamin D level and mortality in prostate cancer patients: a dose-response meta-analysis

Previous studies investigating the association of circulating 25-hydroxyvitamin D level with prognosis of prostate cancer yielded controversial results. We conducted a dose-response meta-analysis to elucidate the relationship. PubMed and EMBASE were searched for eligible studies up to July 15, 2018. We performed a dose-response meta-analysis using random-effect model to calculate the summary hazard ratio (HR) and 95% CI of mortality in patients with prostate cancer. Seven eligible cohort studies with 7808 participants were included. The results indicated that higher vitamin D level could reduce the risk of death among prostate cancer patients. The summary HR of prostate cancer-specific mortality correlated with an increment of every 20 nmol/L in circulating vitamin D level was 0.91, with 95% CI 0.87-0.97, P = 0.002. The HR for all-cause mortality with the increase of 20 nmol/L vitamin D was 0.91 (95% CI: 0.84-0.98, P = 0.01). Sensitivity analysis suggested the pooled HRs were stable and not obviously changed by any single study. No evidence of publications bias was observed. This meta-analysis suggested that higher 25-hydroxyvitamin D level was associated with a reduction of mortality in prostate cancer patients and vitamin D is an important protective factor in the progression and prognosis of prostate cancer.

Polymeric nanocapsules as drug carriers for sustained anticancer activity of calcitriol in breast cancer cells

Clinical use of calcitriol (1,25-dihydroxyvitamin D₃) as an anticancer agent is currently limited by the requirement of supraphysiological doses and associated hypercalcemia. Nanoencapsulation of calcitriol is a strategy to overcome these drawbacks, allowing reduced administrated doses and/or frequency, while retaining the therapeutic activity towards cancer cells. For this purpose, we investigated the impact of calcitriol encapsulation on its antiproliferative activity and optimized formulation parameters with that respect. Calcitriol-loaded polymeric nanoparticles with different polymer:oil ratios were prepared by the nanoprecipitation method. Nanoparticles had similar mean size (200 nm) and EE (85%) whereas their release profile strongly depended on formulation parameters. Antiproliferative and cytotoxic activities of formulated calcitriol were evaluated in vitro using human breast adenocarcinoma cells (MCF-7) and showed that calcitriol-induced cell growth inhibition was closely related to its release kinetics. For the most suitable formulation, a sustained cell growth inhibition was observed over 10 days compared to free form. Advantages of calcitriol encapsulation and the role of formulation parameters on its biological activity in vitro were demonstrated. Selected nanoparticle formulation is a promising calcitriol delivery system ensuring a prolonged anticancer activity that could improve its therapeutic efficiency.

Calcitriol and cancer therapy: A missed opportunity

The vitamin D receptor is expressed in most tissues of the body - and the cancers that arise from those tissues. The vitamin D signaling pathway is active in those tissues and cancers. This is at least consistent with the hypothesis that perturbing this signaling may have a favorable effect on the genesis and growth of cancers. Epidemiologic data indicate that vitamin D signaling may be important in the initiation and outcome of a number of types of cancer. Many studies have shown that calcitriol (1,25 dihydroxycholecalciferol) and other vitamin D compounds have antiproliferative, pro-apoptotic, anti-cell migration and antiangiogenic activity in a number of preclinical studies in many different cancer types. Unfortunately, the assessment of the activity of calcitriol or other vitamin D analogues in the treatment of cancer, as single agents or in combination with other anticancer agents has been stymied by the failure to adhere to commonly accepted principles of drug development and clinical trials conduct.

Does the association of prostate cancer with night-shift work differ according to rotating vs. fixed schedule? A systematic review and meta-analysis

BACKGROUND

Recent studies suggested that the relation between night-shift work and prostate cancer may differ between rotating and fixed schedules.

OBJECTIVES

We aimed to quantify the independent association between night-shift work and prostate cancer, for rotating and fixed schedules.

METHODS

We searched MEDLINE for studies assessing the association of night-shift work, by rotating or fixed schedules, with prostate cancer. We computed summary relative risk (RR) estimates with 95% confidence intervals (95% CI) using the inverse variance method and quantified heterogeneity using the I² statistic. Meta-regression analysis was used to compare the summary RR estimates for rotating and fixed schedules, while reducing heterogeneity.

RESULTS

A total of nine studies assessed the effect of rotating and, in addition, four of them provided the effect of fixed night-shift work, in relation to daytime workers. Rotating night-shift work was associated with a significantly increased risk of prostate cancer (RR = 1.06, 95% CI of 1.01 to 1.12; I² = 50%), but not fixed night-shift work (RR of 1.01, 95% CI of 0.81 to 1.26; I² = 33%). In meta-regression model including study design, type of population, and control of confounding, the summary RR was 20% higher for rotating vs. fixed schedule, with heterogeneity fully explained by these variables.

CONCLUSIONS

This is the first meta-analysis suggesting that an increased risk of prostate cancer may be restricted to workers with rotating night shifts. However, the association was weak and additional studies are needed to further clarify this relation before it can be translated into measures for risk reduction in occupational settings.

Vitamin D Receptor Signaling and Cancer

The vitamin D receptor (VDR) binds the secosteroid hormone 1,25(OH)₂D₃ with high affinity and regulates gene programs that control a serum calcium levels, as well as cell proliferation and differentiation. A significant focus has been to exploit the VDR in cancer settings. Although preclinical studies have been strongly encouraging, to date clinical trials have delivered equivocal findings that have paused the clinical translation of these compounds. However, it is entirely possible that mining of genomic data will help to refine precisely what are the key anticancer actions of vitamin D compounds and where these can be used most effectively.

Vitamin D supplementation decreases serum 27-hydroxycholesterol in a pilot breast cancer trial

PURPOSE

27-hydroxycholesterol (27HC), an endogenous selective estrogen receptor modulator (SERM), drives the growth of estrogen receptor-positive (ER+) breast cancer. 1,25-dihydroxyvitamin D (1,25(OH)₂D), the active metabolite of vitamin D, is known to inhibit expression of CYP27B1, which is very similar in structure and function to CYP27A1, the synthesizing enzyme of 27HC. Therefore, we hypothesized that 1,25(OH)₂D may also inhibit expression of CYP27A1, thereby reducing 27HC concentrations in the blood and tissues that express CYP27A1, including breast cancer tissue.

METHODS

27HC, 25-hydroxyvitamin D (25OHD), and 1,25(OH)₂D were measured in sera from 29 breast cancer patients before and after supplementation with low-dose (400 IU/day) or high-dose (10,000 IU/day) vitamin D in the interval between biopsy and surgery.

RESULTS

A significant increase (p = 4.3E-5) in 25OHD and a decrease (p = 1.7E-1) in 27HC was observed in high-dose versus low-dose vitamin D subjects. Excluding two statistical outliers, 25OHD and 27HC levels were inversely correlated (p = 7.0E-3).

CONCLUSIONS

Vitamin D supplementation can decrease circulating 27HC of breast cancer patients, likely by CYP27A1 inhibition. This suggests a new and additional modality by which vitamin D can inhibit ER+ breast cancer growth, though a larger study is needed for verification.

1,25D3 differentially suppresses bladder cancer cell migration and invasion through the induction of miR-101-3p

Metastasis is the major cause of bladder cancer death. 1,25D₃, the active metabolite of vitamin D, has shown anti-metastasis activity in several cancer model systems. However, the role of 1,25D₃ in migration and invasion in bladder cancer is unknown. To investigate whether 1,25D₃ affects migration and invasion, four human bladder cell lines with different reported invasiveness were selected: low-invasive T24 and 253J cells and highly invasive 253J-BV and TCCSUP cells. All of the four bladder cancer cells express endogenous and inducible vitamin D receptor (VDR) as examined by immunoblot analysis. 1,25D₃ had no effect on the proliferation of bladder cancer cells as assessed by MTT assay. In contrast, 1,25D₃ suppressed migration and invasion in the more invasive 253J-BV and TCCSUP cells, but not in the low-invasive 253J and T24 cells using “wound” healing, chemotactic migration and Matrigel-based invasion assays. 1,25D₃ promoted the expression of miR-101-3p and miR-126-3p in 253J-BV cells as examined by qRT-PCR. miR-101-3p inhibitor partially abrogated and pre-miR-101-3p further suppressed the inhibition of 1,25D₃ on migration and invasion in 253J-BV cells. Further, 1,25D₃ enhanced VDR recruitment to the promoter region of miR-101-3p using ChIP-qPCR assay. 1,25D₃ enhanced the promoter activity of miR-101-3p as evaluated by luciferase reporter assay. Taken together, 1,25D₃ suppresses bladder cancer cell migration and invasion in two invasive/migration competent lines but not in two less invasive/motile lines, which is partially through the induction of miR-101-3p expression at the transcriptional level.

microRNAs and DICER1 are regulated by 1,25-dihydroxyvitamin D in prostate stroma

Vitamin D deficiency increases the risk of lethal prostate adenocarcinomas (PCa) and the majority of older men are deficient. Although PCa arises from the epithelium, the surrounding stroma has hormonal regulatory control over the epithelium and contributes to carcinogenesis. Herein, we describe regulation of microRNAs (miRs) by the active hormone dihydroxyvitamin D (1,25(OH)₂D) in human prostate stroma. 1,25(OH)₂D binds the vitamin D receptor (VDR) transcription factor to regulate gene expression, including miRs, which have emerged as potent regulators of protein expression. 1,25(OH)₂D-regulated miRs were identified by profiling in primary human prostatic stromal cells (PrS) and three miRs, miR-126-3p, miR 154-5p and miR-21-5p were subsequently validated in laser-capture micro-dissected prostate stromal tissue from a vitamin D3 clinical trial (N=45). Regulation of these miRs by 1,25(OH)₂D was VDR-dependent. Network analysis of known and putative mRNA targets of these miRs was enriched with cancer and inflammation pathways, consistent with known roles of stroma and of vitamin D in carcinogenesis. Expression of the miR processing ribonuclease, DICER1, positively correlated with vitamin D metabolite levels in the clinical trial specimens. High epithelial/stromal ratios of DICER1 were significantly associated biochemical recurrence (OR 3.1, p=0.03) in a tissue microarray of 170 matched PCa patients. In summary, these results underscore the role of the prostate stroma in regulating responses to the hormone 1,25(OH)₂D and identified miRs and DICER1 as being regulated in human prostate stroma. Regulation of stromal DICER1 by 1,25(OH)₂D may also have clinical relevance in protection against aggressive PCa.

Prostatic compensation of the vitamin D axis in African American men

BACKGROUND. African American (AA) men are disproportionately affected by both prostate cancer (PCa) and vitamin D deficiency compared with European American (EA) men. Vitamin D deficiency is linked to increased PCa aggressiveness and mortality. Therefore, it has been hypothesized that vitamin D deficiency may contribute to the PCa disparity between AA and EA men. METHODS. We studied a cross sectional group of 60 PCa patients (AA, n = 31; EA, n = 29) who underwent radical prostatectomy. Vitamin D metabolites 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)₂D) were measured in the serum and tissue by uHPLC-MS-MS. Tissue was laser capture microdissected, and gene expression was quantified by microarray. DNA isolated from whole blood was genotyped for West African ancestry markers and vitamin D-related SNPs. RESULTS. Serum concentrations of 25(OH)D were lower in AAs, but concentrations of 1,25(OH)₂D in the prostate tissue were higher compared with EAs. Expression of the vitamin D receptor was higher in prostate tissue from AAs. Expression of the extracellular receptor of vitamin D binding protein, LRP2, was positively associated with West African ancestry and inversely associated with tissue 25(OH)D concentrations in AAs. CONCLUSIONS. The relationships between vitamin D binding protein LRP2 and vitamin D metabolites suggest that the prohormone is actively transported into the prostate, followed by intraprostatic conversion to the active hormone, rather than passive diffusion. These findings support the presence of a compensatory response in prostate tissue to vitamin D deficiency in AAs and reveal a previously unknown complexity involving tissue distribution of vitamin D metabolites. FUNDING. Department of Defense Prostate Cancer Research Program Idea Award for Disparities Research PC121923 (LN and RK) and the NIH 1R01MD007105 (RK).

Race and BMI modify associations of calcium and vitamin D intake with prostate cancer

BACKGROUND

African Americans have disproportionately higher burden of prostate cancer compared to European Americans. However, the cause of prostate cancer disparities is still unclear. Several roles have been proposed for calcium and vitamin D in prostate cancer pathogenesis and progression, but epidemiologic studies have been conducted mainly in European descent populations. Here we investigated the association of calcium and vitamin D intake with prostate cancer in multiethnic samples.

METHODS

A total of 1,657 prostate cancer patients who underwent screening and healthy controls (888 African Americans, 620 European Americans, 111 Hispanic Americans, and 38 others) from Chicago, IL and Washington, D.C. were included in this study. Calcium and vitamin D intake were evaluated using food frequency questionnaire. We performed unconditional logistic regression analyses adjusting for relevant variables.

RESULTS

In the pooled data set, high calcium intake was significantly associated with higher odds for aggressive prostate cancer (OR_{Quartile 1 vs. Quartile 4} = 1.98, 95% C.I.: 1.01-3.91), while high vitamin D intake was associated with lower odds of aggressive prostate cancer (OR_{Quartile 1 vs. Quartile 4} = 0.38, 95% C.I.: 0.18-0.79). In African Americans, the association between high calcium intake and aggressive prostate cancer was statistically significant (OR_{Quartile 1 vs. Quartile 4} = 4.28, 95% C.I.: 1.70-10.80). We also observed a strong inverse association between total vitamin D intake and prostate cancer in African Americans (OR_{Quartile 1 vs. Quartile 4} = 0.06, 95% C.I.: 0.02-0.54). In European Americas, we did not observe any significant associations between either calcium or vitamin D intake and prostate cancer. In analyses stratifying participants based on Body Mass Index (BMI), we observed a strong positive association between calcium and aggressive prostate cancer and a strong inverse association between vitamin D intake and aggressive prostate cancer among men with low BMI (<27.8 kg/m²), but not among men with high BMI (≥27.8 kg/m²). Interactions of race and BMI with vitamin D intake were significant (P _Interaction < 0.05).

CONCLUSION

Calcium intake was positively associated with aggressive prostate cancer, while vitamin D intake exhibited an inverse relationship. However, these associations varied by race/ethnicity and BMI. The findings from this study may help develop better prostate cancer prevention and management strategies.

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.

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.

The Use of 1α,25-Dihydroxyvitamin D₃ as an Anticancer Agent

The notion that vitamin D can influence the incidence of cancer arose from epidemiological studies. The major source of vitamin D in the organism is skin production upon exposure to ultra violet-B. The very first observation of an inverse correlation between exposure of individuals to the sun and the likelihood of cancer was reported as early as 1941. In 1980, Garland and Garland hypothesised, from findings from epidemiological studies of patients in the US with colon cancer, that vitamin D produced in response to sun exposure is protective against cancer as opposed to sunlight per se. Later studies revealed inverse correlations between sun exposure and the occurrence of prostate and breast cancers. These observations prompted laboratory investigation of whether or not vitamin D had an effect on cancer cells. Vitamin D is not active against cancer cells, but the most active metabolite 1α,25-dihydroxyvitamin D₃ (1,25D) has profound biological effects. Here, we review the anticancer action of 1,25D, clinical trials of 1,25D to date and the prospects of the future therapeutic use of new and low calcaemic analogues.

DNA Repair in Despair-Vitamin D Is Not Fair

The role of vitamin D as a treatment option for neoplastic diseases, once considered to have a bright future, remains controversial. The preclinical studies discussed herein show compelling evidence that Vitamin D Derivatives (VDDs) can convert some cancer and leukemia cells to a benign phenotype, by differentiation/maturation, cell cycle arrest, or induction of apoptosis. Furthermore, there is considerable, though still evolving, knowledge of the molecular mechanisms underlying these changes. However, the attempts to clearly document that the treatment outcomes of human neoplastic diseases can be positively influenced by VDDs have been, so far, disappointing. The clinical trials to date of VDDs, alone or combined with other agents, have not shown consistent results. It is our contention, shared by others, that there were limitations in the design or execution of these trials which have not yet been fully addressed. Based on the connection between upregulation of JNK by VDDs and DNA repair, we propose a new avenue of attack on cancer cells by increasing the toxicity of the current, only partially effective, cancer chemotherapeutic drugs by combining them with VDDs. This can impair DNA repair and thus kill the malignant cells, warranting a comprehensive study of this novel concept. J. Cell. Biochem. 117: 1733-1744, 2016. © 2016 Wiley Periodicals, Inc.

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.

A systematic review of dietary, nutritional, and physical activity interventions for the prevention of prostate cancer progression and mortality

PURPOSE

Given the long-term, although potentially fatal, nature of prostate cancer, there is increasing observational evidence for the reduction in disease progression and mortality through changes in lifestyle factors.

METHODS

We systematically reviewed dietary, nutritional, and physical activity randomized interventions aimed at modifying prostate cancer progression and disease-specific mortality, including a detailed assessment of risk of bias and methodological quality.

RESULTS

Forty-four randomized controlled trials of lifestyle interventions, with prostate cancer progression or mortality outcomes, were identified. Substantial heterogeneity of the data prevented a meta-analysis. The included trials involved 3,418 prostate cancer patients, median 64 men per trial, from 13 countries. A trial of a nutritional supplement of pomegranate seed, green tea, broccoli, and turmeric; a trial comparing flaxseed, low-fat diet, flaxseed, and low-fat diet versus usual diet; and a trial supplementing soy, lycopene, selenium, and coenzyme Q10, all demonstrated beneficial effects. These trials were also assessed as having low risk of bias and high methodological quality (as were seven other trials with no evidence of benefit). The remaining trials were either underpowered, at high or unclear risk of bias, inadequately reported, of short duration or measured surrogate outcomes of unproven relationship to mortality or disease progression, which precluded any benefits reported being reliable.

CONCLUSION

Large, well-designed randomized trials with clinical endpoints are recommended for lifestyle modification interventions.

Hepatocellular carcinoma cells express 25(OH)D-1α-hydroxylase and are able to convert 25(OH)D to 1α,25(OH)₂D, leading to the 25(OH)D-induced growth inhibition

Hepatocellular carcinoma (HCC) is the most diagnosed liver cancer without effective treatments available for advanced HCC. Vitamin D is getting popular due to its anti-cancer characteristics. However, the clinical application of 1α,25(OH)2D, the active form of vitamin, is hampered by its hypercalcemia side effect. 1α,25(OH)2D is converted from 25(OH)D, the index of serum vitamin D status, by CYP27B1, which is originally found in kidneys but recently detected in non-renal tissues. 25(OH)D has been shown to repress some cancers expressing CYP27B1 due to the local conversion of 25(OH)D to 1α,25(OH)2D, which works in a intra-, auto-, or paracrine manner and thus minimizes the risk of hypercalcemia. In this study, we found CYP27B1 expression in human hepatocyte, HCC, and HepG2 cells. As we treated HepG2 cells with 25(OH)D, the 1α,25(OH)2D target gene CYP24A1 expression was increased and was further upregulated as CYP27B1 transfection or downregulated as CYP27B1 knockdown. Other 1α,25(OH)2D target genes in HepG2 cells, p21 and p27 were also stimulated by 25(OH)D after CYP27B1 transfection. Further, 25(OH)D could inhibit HepG2 cells growth, which was potentiated by CYP27B1 transfection. Collectively, we showed for the first time that HCC expressed CYP27B1 and was able to covert 25(OH)D to 1α,25(OH)2D in vitro, thus responsive to 25(OH)D treatment. Our data justifies the application of 25(OH)D and CYP27B1 gene transfection therapy in further HCC treatment studies.

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.

Comparison of digital image analysis and visual scoring of KI-67 in prostate cancer prognosis after prostatectomy

Background

The tumor proliferative index marker Ki-67 was shown to be associated with clinically significant outcomes in prostate cancer, but its clinical application has limitations due to lack of uniformity and consistency in quantification. Our objective was to compare the measurements obtained with digital image analysis (DIA) versus virtual microscopy (visual scoring (VS)).

Methods

To do so, we compared the measurement distributions of each technique and their ability to predict clinically useful endpoints. A tissue microarray series from a cohort of 225 men who underwent radical prostatectomy was immunostained for Ki-67. The percentage of Ki-67 positive nuclei in malignant cells was assessed both by VS and DIA, and a H–score was calculated. The distribution and predictive ability of these scoring methods to predict biochemical recurrence (BCR) and death from prostate cancer (DPCa) were compared using Mann–Whitney test and C-index.

Results

The measurements obtained with VS were similar to the DIA measurements (p = 0.73) but dissimilar to the H-score (p < 0.001). Cox regression models showed that Ki-67 was associated with BCR (HR 1.46, 95 % CI 1.10-1.94) and DPCa (HR 1.26, 95 % CI 1.06-1.50). C-indexes revealed that Ki-67 was a better predictor of DPCa (0.803, 0.8059 and 0.789; VS, DIA and H-score, respectively) than of BCR (0.625, 0.632 and 0.604; VS, DIA and H-score, respectively).

Conclusion

The measurement distributions and the predictive abilities of VS and DIA were similar and presented the same predictive behaviour in our cohort, supporting the role of Ki-67 proliferative index as an important prognostic factor of BCR and DPCa in prostate cancer post RP.

Virtual Slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/6656878501536663

Electronic supplementary material

The online version of this article (doi:10.1186/s13000-015-0294-0) contains supplementary material, which is available to authorized users.