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

Cellular responses to silencing of PDIA3 (protein disulphide-isomerase A3): Effects on proliferation, migration, and genes in control of active vitamin D

The active form of vitamin D, 1,25-dihydroxyvitamin D3, is known to act via VDR (vitamin D receptor), affecting several physiological processes. In addition, PDIA3 (protein disulphide-isomerase A3) has been associated with some of the functions of 1,25-dihydroxyvitamin D3. In the present study we used siRNA-mediated silencing of PDIA3 in osteosarcoma and prostate carcinoma cell lines to examine the role(s) of PDIA3 for 1,25-dihydroxyvitamin D3-dependent responses. PDIA3 silencing affected VDR target genes and significantly altered the 1,25-dihydroxyvitamin D3-dependent induction of CYP24A1, essential for elimination of excess 1,25-dihydroxyvitamin D3. Also, PDIA3 silencing significantly altered migration and proliferation in prostate PC3 cells, independently of 1,25-dihydroxyvitamin D3. 1,25-Dihydroxyvitamin D3 increased thermostability of PDIA3 in cellular thermal shift assay, supporting functional interaction between PDIA3 and 1,25-dihydroxyvitamin D3-dependent pathways. In summary, our data link PDIA3 to 1,25-dihydroxyvitamin D3-mediated signalling, underline and extend its role in proliferation and reveal a novel function in maintenance of 1,25-dihydroxyvitamin D3 levels.

The Impact of Baseline Vitamin D Level in Patients Receiving Gefitinib-Directed Therapy for EGFR-Mutant Non-Small-Cell Lung Cancer

Background

There is contradicting evidence on vitamin D levels and cancer mortality rates. In this study, we aimed to evaluate the impact of baseline vitamin D level on the outcome in patients with estimated glomerular filtration rate (EGFR)-mutant advanced non-small-cell lung cancer (NSCLC) who received either gefitinib or gefitinib with chemotherapy (pemetrexed and carboplatin) as first-line therapy in a prospective randomized study.

Methods

This was a post hoc analysis of a phase III randomized trial comparing gefitinib with gefitinib with carboplatin and pemetrexed in patients with advanced NSCLC with activating EGFR mutations in the first-line setting. As a part of regular practice, baseline vitamin D levels were measured using circulating 25(OH) levels in blood. We included 334 patients who had baseline vitamin D levels in the study and evaluated the effect of the vitamin D level on oncologic outcomes.

Results

There were 136 (40.7%) patients with a sufficient (>20 ng/mL) baseline vitamin D level, and 198 (59.3%) patients who were deficient in vitamin D (<20 ng/mL). The median progression-free survival (PFS) in patients with normal vitamin D levels was 17 months, whereas that in patients with deficient vitamin D levels was 15 months, with a hazard ratio of 1.45 (95% confidence interval [CI] = 1.03-2.06). The median overall survival (OS) in patients with normal vitamin D levels was 28.6 months, whereas that in patients with deficient vitamin D levels was 28.5 months, with a hazard ratio of 1.17 (95% CI = 0.81-1.68). On multivariate analysis, only 2 factors impacted the PFS, the baseline vitamin D level, and the treatment regimen; other factors like age, sex, disease stage, and performance status did not.

Conclusions

Baseline vitamin D levels have a significant impact on PFS, whereas OS is not affected by the baseline vitamin D levels on patients receiving targeted therapy for EGFR-mutant lung cancer.

Trial registration

The trial was prospectively registered with the Clinical Trial Registry of India, registration number CTRI/2016/08/007149. The date of the registration was 5 August 2016.

Association between vitamin D receptor gene polymorphisms and genetic susceptibility to benign prostatic hyperplasia: A systematic review and meta-analysis

BACKGROUND

Benign prostatic hyperplasia (BPH) is one of the global public health challenges due to the complexity of its mechanisms of occurrence. Many studies have suggested that vitamin D receptor gene polymorphisms are associated with BPH susceptibility. Still, their conflicting findings need to be analyzed in aggregate to gain a better understanding.

METHODS

We identified 10 trials involving 1539 BPH cases and 1915 controls through a systematic search of Embase using, data obtained from the Web of Science, PubMed, and China Knowledge Network databases as of December 31, 2021. A meta-analysis was performed to investigate the association between 4 constant polymorphisms of this associated vitamin D receptor gene (Fok-1, Bsm-1, Taq-1, and Apa-1) and BPH risk.

RESULTS

In the overall population analysis, a significant positive association with BPH risk was found only in the Taq-1 variant (P < .001). Of these, the pure-hybrid model (95% confidence interval [CI] = 1.384-3.196), the heterozygous model (95% CI = 1.207-2.021), the dominant model (95% CI = 1.312-2.133) and the allelic inheritance model (95% CI = 1.205-1.730) showed low heterogeneity. In subtype analyses, Bsm-1 variants showed a significant association with BPH risk for both the recessive (95% CI = 0.100-0.943, P = .039) and over-dominant (95% CI = 1.553-3.100, P = 0) models in the Caucasian population, and for the recessive (95% CI = 1.242-3.283, P = .039) and over-dominant (95% CI = 0.281-0.680, P = 0) models in the Asian population. In addition, a high degree of heterogeneity was found in the subgroup analysis of the association between Fok-1 variants and BPH risk.

CONCLUSION

Overall, there is an association between vitamin D receptor polymorphisms and BPH risk. Identification of BPH susceptibility by vitamin D receptor gene polymorphisms has potential.

Cytochrome P450 genes expression in human prostate cancer

CYP-dependent metabolites play a critical role in regulating the cell cycle, as well as the proliferative, invasive, and migratory activity of cancer cells. We conducted a study to analyze the relative gene expression of various CYPs (CYP7B1, CYP27A1, CYP39A1, CYP51, CYP1B1, CYP3A5, CYP4F8, CYP5A1, CYP4F2, CYP2J2, CYP2E1, CYP2R1, CYP27B1, CYP24A1) in 41 pairs of prostate samples (tumor and conventional normal tissues) using qPCR. Our analysis determined significant individual variability in the expression levels of all studied CYPs, both in the tumor and in conventionally normal groups. However, when we performed a paired test between the tumor and normal groups, we found no significant difference in the expression of the studied genes. We did observe a tendency to increase the level of CYP1B1 expression in the tumor group. We also did not find any significant difference between the levels of the studied CYPs in the tumor and conventional normal groups at different stages of prostate cancer and pathomorphological indicators. Correlation analysis revealed the presence of a positive relationship between the expressions of some cholesterol-metabolizing CYP genes, as well as between genes responsible for vitamin D biosynthesis and cholesterol biosynthesis. We observed significant correlative relationships between the expression of CYPs and some prostate cancer-related genes (CDH2, MMP9, SCHLAP1, GCR, CYP17A1, ACTA2, CXCL14, FAP, CCL17, MSMB, IRF1, VDR). Therefore, the expression of CYPs is not directly associated with prostate cancer but is largely determined by genetic, epigenetic factors, as well as endogenous substrates and xenobiotics. The significant correlative relationship between CYPs and genes associated with cancer may indicate common regulatory pathways that may have a synergistic effect on the tumor, ensuring the survival of cancer cells.

Associations of intakes of total protein, protein from dairy sources, and dietary calcium with risks of colorectal, breast, and prostate cancer: a prospective analysis in UK Biobank

BACKGROUND

Evidence concerning intakes of protein or sources of dairy protein and risks of colorectal, breast, and prostate cancers is inconclusive.

METHODS

Using a subsample of UK Biobank participants who completed ≥2 (maximum of 5) 24-h dietary assessments, we estimated intakes of total protein, protein from total dairy products, milk, and cheese, and dietary calcium in 114,217 participants. Hazard ratios (HRs) and 95% confidence intervals (CI) were estimated using multivariable-adjusted Cox regression.

RESULTS

After a median of 9.4 years of follow-up, 1193 colorectal, 2024 female breast, and 2422 prostate cancer cases were identified. There were inverse associations of total dairy protein, protein from milk, and dietary calcium intakes with colorectal cancer incidence (HRQ4 vs Q1:0.80, 95% CI: 0.67-0.94; 0.79, 0.67-0.94; 0.71, 0.58-0.86, respectively). We also observed positive associations of milk protein and dietary calcium with prostate cancer risk (HRQ4 vs Q1:1.12, 1.00-1.26 and 1.16, 1.01-1.33, respectively). No significant associations were observed between intake of dairy protein and breast cancer risk. When insulin-like growth factor-I concentrations measured at recruitment were added to the multivariable-adjusted models, associations remained largely unchanged. Analyses were also similar when looking at total grams of dairy products, milk, and cheese.

CONCLUSION

Further research is needed to understand the mechanisms underlying the relationships of dairy products with cancer risk and the potential roles of dietary protein and calcium.

Influence of sunlight on the association between 25-hydroxyvitamin D levels and sleep quality in Brazilian adults: A population-based study

OBJECTIVES

This study aimed to evaluate the association of vitamin D with sleep quality during the COVID-19 pandemic and the influence of daily sunlight on this association.

METHODS

This cross-sectional, population-based study among adults stratified by multistage probability cluster sampling was conducted from October to December 2020 in the Iron Quadrangle region of Brazil. The outcome was sleep quality, evaluated by the Pittsburgh Sleep Quality Index. Vitamin D (25-hydroxyvitamin D) concentrations were determined by indirect electrochemiluminescence and a deficiency was classified as 25(OH)D < 20 ng/mL. To assess sunlight, the average daily sunlight exposure was calculated and was classified as insufficient when less than 30 min/d. Multivariate logistic analysis was used to estimate the association between vitamin D and sleep quality. A directed acyclic graph was used to select minimal and sufficient sets of adjustment variables for confounding from the backdoor criterion.

RESULTS

In a total of 1709 individuals evaluated, the prevalence of vitamin D deficiency was 19.8% (95% CI, 15.5-24.9%), and the prevalence of poor sleep quality was 52.5% (95% CI, 48.6-56.4%). In multivariate analysis, vitamin D was not associated with poor sleep quality in individuals with sufficient sunlight. Moreover, in individuals with insufficient sunlight, vitamin D deficiency was associated with poor sleep quality (odds ratio [OR], 2.02; 95% CI, 1.10-3.71). Furthermore, each 1-ng/mL increase in vitamin D levels reduced the chance of poor sleep quality by 4.2% (OR, 0.96; 95% CI, 0.92-0.99).

CONCLUSIONS

Vitamin D deficiency was associated with poor sleep quality in individuals with insufficient exposure to sunlight.

The Effect of Vitamin D and Its Analogs in Ovarian Cancer

Ovarian cancer is one of the deadliest cancers in women, due to its heterogeneity and usually late diagnosis. The current first-line therapies of debulking surgery and intensive chemotherapy cause debilitating side effects. Therefore, there is an unmet medical need to find new and effective therapies with fewer side effects, or adjuvant therapies, which could reduce the necessary doses of chemotherapeutics. Vitamin D is one of the main regulators of serum calcium and phosphorus homeostasis, but it has also anticancer effects. It induces differentiation and apoptosis, reduces proliferation and metastatic potential of cancer cells. However, doses that would be effective against cancer cause hypercalcemia. For this reason, synthetic and less calcemic analogs have been developed and tested in terms of their anticancer effect. The anticancer role of vitamin D is best understood in colorectal, breast, and prostate cancer and much less research has been done in ovarian cancer. In this review, we thus summarize the studies on the role of vitamin D and its analogs in vitro and in vivo in ovarian cancer models.

Laser Ablation ICP-MS Analysis of Chemically Different Regions of Rat Prostate Gland with Implanted Cancer Cells

The comparison of tissues analyzed by LA-ICP-MS is challenging in many aspects, both medical and mathematical. The concept of distinguishing regions of interest (ROIs) was proposed in the literature, allowing for data reduction and targeted comparative analysis. ROIs can be drawn before any analysis, by indicating the anatomical parts of tissue, or after the first step of analysis, by using elemental distribution maps and characteristic regions of enrichment in selected elements. A simple method for identifying different regions, without the manual extraction of image fragments, is highly needed in biological experiments, where large groups of individuals (with samples taken from each of them) is very common. In the present study, two ROIs were distinguished: (1) tissue-rich in fat (and tissue-poor in water); and (2) tissue-rich in water (and tissue-poor in fat). ROIs were extracted mathematically, using an algorithm based on the relationship between 13C and 23Na signal intensities. A cut-off point was indicated in the point of the simultaneous decrease in 13C and increase in 23Na signal intensity. Separate analyses of chemically different ROIs allow for targeted comparison, which is a great advantage of laser ablation over liquid introductions to ICP-MS. In the present experiment, tissues were provided from animals with implanted prostate cancer cells as well as supplemented with mineral compounds particularly important both for prostate gland functions (Zn and Se) and neoplastic processes (Ca, Fe, and Cu). One of the goals was to try to determine whether dietary supplementation qualitatively and quantitatively affects the mineral composition of the prostate gland.

Identification of kinase inhibitors that rule out the CYP27B1-mediated activation of vitamin D: an integrated machine learning and structure-based drug designing approach

CYP27B1, a cytochrome P450-containing hydroxylase enzyme, converts vitamin D precursor calcidiol (25-hydroxycholecalciferol) to its active form calcitriol (1α,25(OH)₂D₃). Tyrosine kinase inhibitor such as imatinib is reported to interfere with the activation of vitamin D₃ by inhibiting CYP27B1 enzyme. Consequently, there is a decrease in the serum levels of active vitamin D that in turn may increase the relapse risk among the cancer patients treated with imatinib. Within this framework, the current study focuses on identifying other possible kinase inhibitors that may affect the calcitriol level in the body by inhibiting CYP27B1. To achieve this, we explored multiple machine learning approaches including support vector machine (SVM), random forest (RF), and artificial neural network (ANN) to identify possible CYP27B1 inhibitors from a pool of kinase inhibitors database. The most reliable classification model was obtained from the SVM approach with Matthews correlation coefficient of 0.82 for the external test set. This model was further employed for the virtual screening of kinase inhibitors from the binding database (DB), which tend to interfere with the CYP27B1-mediated activation of vitamin D. This screening yielded around 4646 kinase inhibitors that were further subjected to structure-based analyses using the homology model of CYP27B1, as the 3D structure of CYP27B1 complexed with heme was not available. Overall, five kinase inhibitors including two well-known drugs, i.e., AT7867 (Compound-2) and amitriptyline N-oxide (Compound-3), were found to interact with CYP27B1 in such a way that may preclude the conversion of vitamin D to its active form and hence testify the impairment of vitamin D activation pathway.

Altered expression of cytochrome P450 enzymes involved in metabolism of androgens and vitamin D in the prostate as a risk factor for prostate cancer

Prostate cancer is the most common malignant disease among men. The signaling pathways, regulated by the androgen and vitamin D receptors, play a key role in prostate cancer. The intracellular level of androgens and vitamin D determines not only receptor functionality, but also the efficacy of cellular processes regulated by them (cell proliferation, apoptosis, differentiation etc.). It is known that several androgen-metabolizing P450s (CYP3A4/5/43 and CYP2B6) and P450 enzymes (CYP2R1, CYP27A1, CYP27B1, CYP24A1, CYP3A4, CYP2J2), which are necessary for vitamin D metabolism, are expressed in the prostate. It was shown that alterations in an expression pattern of the certain cytochrome P450s might lead to the development of castration-resistant cancer (CYP3A4, CYP2J2, CYP24A1), and to chemo-resistance (CYP3A4, CYP3A5, CYP2B6) and early mortality (CYP2B6, CYP27A1, CYP24A1). Moreover, steroidogenic CYPs (CYP17A1, CYP11A1) are not expressed in normal prostate tissue. Alterations in their expression levels in steroidogenic tissues are closely associated with carcinogenesis, and, most importantly, with the development of aggressive forms of prostate cancer. Hence, it is important, to study how expression of CYPs in the prostate might be regulated, to understand the mechanisms of disease development and to improve the effectiveness of therapy. Several CYPs (CYP3A43, CYP2B6, CYP27A1, CYP24A1) can be considered as prognostic and diagnostic markers of prostate cancer. To propose personalized treatment, individual differences in CYP expression should be taken into account.

On Mendelian randomization analysis of case-control study

Mendelian randomization (MR) analysis uses genotypes as instruments to estimate the causal effect of an exposure in the presence of unobserved confounders. The existing MR methods focus on the data generated from prospective cohort studies. We develop a procedure for studying binary outcomes under a case-control design. The proposed procedure is built upon two working models commonly used for MR analyses and adopts a quasi-empirical likelihood framework to address the ascertainment bias from case-control sampling. We derive various approaches for estimating the causal effect and hypothesis testing under the empirical likelihood framework. We conduct extensive simulation studies to evaluate the proposed methods. We find that the proposed empirical likelihood estimate is less biased than the existing estimates. Among all the approaches considered, the Lagrange multiplier (LM) test has the highest power, and the confidence intervals derived from the LM test have the most accurate coverage. We illustrate the use of our method in MR analysis of prostate cancer case-control data with vitamin D level as exposure and three single nucleotide polymorphisms as instruments.

Dietary lipids and environmental xenobiotics as risk factors for prostate cancer: The role of cytochrome P450

Prostate cancer is one of the most common malignant neoplasms in men. Because of the increase in the number of cases as well as development of cancers resistant to conventional therapy, identification of the new molecular targets for the treatment and prevention is of great importance. For this purpose, many studies are aimed on revealing of molecular mechanisms of prostate cancer development. In this process, dietary lipids and environmental xenobiotics are largely involved and are considered as risk factors. A wide range of endogenous (cholesterol, polyunsaturated fatty acids, etc.) and exogenous (pollutants, drugs) compounds are metabolized in the human organism by cytochrome P450. From other hand, these compounds may alter cytochrome P450 expression levels, especially in prostate, which, in turn, affects cell metabolism. Cytochrome P450 is a member of signaling pathways, regulating cell cycle, apoptosis, invasion and adhesion. Hence, cytochrome P450 most probably plays the important role in initiation and progression of prostate cancer. Based on that, cytochrome P450 enzymes are considered as potential targets for the targeted therapy and prevention, and might serve as specific markers of malignant growth.

25-Hydroxyvitamin D and Total Cancer Incidence and Mortality: A Meta-Analysis of Prospective Cohort Studies

Epidemiological studies have suggested inconclusive associations between 25-hydroxyvitamin D and total cancer incidence and mortality. The aim of this study was to quantitatively assess these associations by combining results from prospective cohort studies. A systematic literature search was implemented in PubMed and Scopus databases in April 2019. Comparing the highest with the lowest categories, the multivariate-adjusted relative risks (RRs) and the corresponding 95% confidence intervals (CIs) were pooled using a random-effects model. A trend estimation was performed using a two-stage, dose-response, meta-analysis method. Twenty-three independent prospective studies were included for data synthesis. Eight studies investigated the association between 25-hydroxyvitamin D and the risk of cancer incidence (7511 events and 70,018 participants), and the summary estimate showed that 25-hydroxyvitamin D is marginally associated with cancer risk (Summary RR = 0.86; 95% CI: 0.73, 1.02; I² = 70.8%; p = 0.001). Sixteen studies investigated the association between 25-hydroxyvitamin D and the risk of cancer mortality (8729 events and 101,794 participants), and a higher 25-hydroxyvitamin D concentration was inversely associated with the risk of cancer mortality (Summary RR = 0.81; 95% CI: 0.71, 0.93; I² = 48.8%, p = 0.012). Dose-response analysis indicated that the risk of cancer incidence was reduced by 7% (RRs = 0.93; 95% CI: 0.91, 0.96), and the risk of cancer mortality was reduced by 2% (RRs = 0.98; 95% CI: 0.97, 0.99), with each 20 nmol/L increment of 25-hydroxyvitamin D concentration. This meta-analysis provides evidence that a higher 25-hydroxyvitamin D concentration is associated with a lower cancer incidence and cancer mortality.

Do dietary calcium and vitamin D matter in men with prostate cancer?

Active surveillance (AS) is an attractive alternative to immediate treatment for men with low-risk prostate cancer. Thus, the identification of environmental factors that promote the progression of indolent disease towards aggressive stages is critical to optimize clinical management. Epidemiological studies suggest that calcium-rich diets contribute to an increased risk of developing prostate cancer and that vitamin D reduces this risk. However, the potential effect of these nutrients on the progression of early-stage prostate tumours is uncertain, as studies in this setting are scarce and have not provided unambiguous conclusions. By contrast, the results of a preclinical study from our own group demonstrate that a diet high in calcium dose-dependently accelerated the progression of early-stage prostate tumours and that dietary vitamin D prevented this effect. The extent to which the conclusions of preclinical and epidemiological studies support a role for calcium and vitamin D and the relevance of monitoring and adjustment of calcium and/or vitamin D intake in patients on AS require further investigation.

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.

[An integral view of cancer (I). The study, classification and reprogramming of the tumoral microclimate]

The group of diseases that we call cancer share a biological structure formed by a complex ecosystem, with altered intercellular communication, information fields, development and tissue function. Beyond the genetic alterations of the tumor cell, the demonstration of an altered ecosystem, with interconnections at systemic levels, opens up a new perspective on cancer biology and behavior. Different tumor facets, such as morphology, classification, clinical aggressiveness, prognosis and response to treatment now appear under a comprehensive vision that offers a new horizon of study, research and clinical management. The Somatic Mutation Theory in cancer, in force for more than one hundred years, is now completed by the study of the tumor microenvironment, the extracellular matrix, the stromal cells, the immune response, the innervation, the nutrition, the mitochondria, the metabolism, the interstitial fluid, the mechanical and electromagnetic properties of the tissue and many other areas of emerging knowledge; thus opening the door to a reprogramming exercise of the tumor phenotype through the modification of the keys offered by this new paradigm. Its recognition makes it possible to go from considering the oncological process as a cellular problem to a supracellular alteration based on the disorganization of tissues, immersed in the relationships of the complex system of the living being.

A Collaborative Analysis of Individual Participant Data from 19 Prospective Studies Assesses Circulating Vitamin D and Prostate Cancer Risk

Previous prospective studies assessing the relationship between circulating concentrations of vitamin D and prostate cancer risk have shown inconclusive results, particularly for risk of aggressive disease. In this study, we examine the association between prediagnostic concentrations of 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)2D] and the risk of prostate cancer overall and by tumor characteristics. Principal investigators of 19 prospective studies provided individual participant data on circulating 25(OH)D and 1,25(OH)2D for up to 13,462 men with incident prostate cancer and 20,261 control participants. ORs for prostate cancer by study-specific fifths of season-standardized vitamin D concentration were estimated using multivariable-adjusted conditional logistic regression. 25(OH)D concentration was positively associated with risk for total prostate cancer (multivariable-adjusted OR comparing highest vs. lowest study-specific fifth was 1.22; 95% confidence interval, 1.13-1.31; P trend < 0.001). However, this association varied by disease aggressiveness (P heterogeneity = 0.014); higher circulating 25(OH)D was associated with a higher risk of nonaggressive disease (OR per 80 percentile increase = 1.24, 1.13-1.36) but not with aggressive disease (defined as stage 4, metastases, or prostate cancer death, 0.95, 0.78-1.15). 1,25(OH)2D concentration was not associated with risk for prostate cancer overall or by tumor characteristics. The absence of an association of vitamin D with aggressive disease does not support the hypothesis that vitamin D deficiency increases prostate cancer risk. Rather, the association of high circulating 25(OH)D concentration with a higher risk of nonaggressive prostate cancer may be influenced by detection bias. SIGNIFICANCE: This international collaboration comprises the largest prospective study on blood vitamin D and prostate cancer risk and shows no association with aggressive disease but some evidence of a higher risk of nonaggressive disease.

Human uterine leiomyoma contains low levels of 1, 25 dihdroxyvitamin D3, and shows dysregulated expression of vitamin D metabolizing enzymes

OBJECTIVES

To evaluate tissue concentration of 1, 25 dihydroxyvitamin D3, and gene expression level of CYP27B1 that codes for 1-α hydroxylase (vitamin D activating enzyme), and CYP24A1 that codes for 24-hydroxylase (vitamin D catabolizing enzyme) in human uterine leiomyoma (ULM), its adjacent myometrium (Myo-F), and normal myometrium (Myo-N).

STUDY DESIGN

Levels of 1, 25 dihydroxyvitamin D3 were measured using HPLC and Diode detectors whereas CYP27B1, and CYP24A1 expressions were assessed using Real-Time PCR in ULM, Myo-F, and Myo-N. Non-parametric statistics were used.

RESULTS

ULMs contained significantly less 1, 25 dihydroxy vitamin D3 compared to Myo-F (3.0, IQR: 1.0-9.0 versus 6.0, IQR: 3.0-13.0 μg/ kg, P value is 0.03). No significant difference was detected between ULM and Myo-N, or Myo-F and Myo-N. Intratumoral level of the active form of vitamin D did not differ according to the type of ULM (submucous or interstitial/subserous), or to the ULM volume. CYP27B1 was expressed in ULM (2.17, IQR: 0.65-4.9), Myo-F (4.94, IQR: 1.04-22.59), and Myo-N (0.99, IQR: 0.49-1.71) to a comparable level. CYP24A1 expression was significantly higher in ULM compared to Myo-N (2.00, IQR: 0.69-10.77 versus 0.22, IQR: 00- 0.96, respectively, P value is 0.04).

CONCLUSIONS

Human ULMs contain significantly lower 1, 25 dihydroxyvitamin D3 than its adjacent myometrium. ULM, Myo-F, and Myo-N express CYP27B1 and CYP24A1. ULMs express significantly higher level of CYP24A1 than normal myometrium indicating that over expression of 24-hydroxylase is a mechanism by which ULMs sustain a relative state of hypovitaminosis D.

Prostate cancer risk factors in black and white men in the NIH-AARP Diet and Health Study

BACKGROUND

There are few prospective studies comparing race-specific associations between diet, nutrients, and health-related parameters, and prostate cancer risk.

METHODS

Race-specific prostate cancer risk associations were examined among men in the National Institutes of Health (NIH)-AARP Diet and Health Study. We identified 1417 cases among black men (209 advanced), and 28,845 among white men (3898 advanced). Cox proportional hazards regression models estimated hazard ratios (HRs) and 95% confidence intervals (CIs). We also evaluated the cumulative change in the HR for black race following adjustment for each factor.

RESULTS

Race-specific prostate cancer associations were similar in black and white men across disease subtypes only for history of diabetes (overall : HR = 0.77, 95% CI: 0.65-0.90 and HR = 0.72, 95% CI: 0.69-0.76, respectively; P_interaction = 0.66). By contrast, there was a positive risk association with height for white men  and  inverse for black men (P_interaction: non-advanced = 0.01; advanced = 0.04). This difference remained among men with at least 2 years of follow-up for non-advanced (P_interaction = 0.01), but not advanced disease (P_interaction = 0.24); or after adjustment for prostate cancer screening (non-advanced P_interaction = 0.53, advanced P_interaction = 0.31). The only other evidence of interaction with race was observed for dietary vitamin D intake and non-advanced disease, but only after adjustment for screening (P_interaction = 0.02). Cumulative adjustment for each factor increased the HR for black race by 32.9% for overall cancer and 12.4% for advanced disease.

CONCLUSIONS

Our data suggest few of the dietary, nutrient, and health-related factors associated with prostate cancer risk in predominantly non-Hispanic white men were associated with risk in black men, and adjustment for these factors widen the black-white difference in risk. Larger studies of black men, particularly with prospective data, are needed to help identify risk factors relevant to this population.

Serum 25-hydroxyvitamin D, vitamin D binding protein, and prostate cancer risk in black men

BACKGROUND

Few studies have prospectively examined the relationship between vitamin D status and prostate cancer risk in black men, a group at high risk for both low vitamin D status and prostate cancer.

METHODS

Among black men in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial, we identified 226 prostate cancer cases and 452 controls matched on age at randomization (±5 years), date of blood draw (±30 days), calendar year of cohort entry, and time since baseline prostate cancer screening (±1 year). Conditional logistic regression was used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between serum 25-hydroxyvitamin D [25(OH)D], vitamin D binding protein (DBP), the 25(OH)D:DBP molar ratio, and prostate cancer risk.

RESULTS

Serum 25(OH)D was not associated with overall prostate cancer (Q4 vs Q1: OR, 0.73; 95% CI, 0.40-1.33; P for trend = .25), although there were apparent inverse associations for nonaggressive disease (global P = .03, clinical stage I/II, and Gleason score <7) and among men ≥62 years old (P for interaction = .04) that were restricted to Q3. Interestingly, serum DBP was significantly inversely associated with prostate cancer risk (Q4 vs Q1: OR, 0.45; 95% CI, 0.20-1.00; P for trend = .03), whereas the 25(OH)D:DBP molar ratio was not. Results were similar when we mutually adjusted for 25(OH)D and DBP, and we found no evidence of interaction between the two.

CONCLUSION

Our study suggests higher (versus lower) circulating DBP may be independently associated with a decreased prostate cancer risk in black men independent of 25(OH)D status. Cancer 2017;123:2698-704. © 2017 American Cancer Society.

Expression pattern of CYP24 in liver during ageing in long-term diabetes

Association of liver calcitriol (active vitamin D metabolite) catabolism with osteomalacia during prolonged use of certain drugs was reported in several recent studies. To examine whether the increased calcitriol catabolism could be a potential link between ageing/diabetes mellitus (DM) and bone loss, we studied the dynamic of expression of CYP24, the main calcitriol catabolising enzyme in the liver of rats during ageing and a long-term experimental DM1. DM1 model was induced with intraperitoneally injected streptozotocin (STZ) (55mg/kg). Sprague-Dawley rats were sacrificed 6 and 12 months after the DM1 induction. The immunohistochemical analyses of CYP24 and transforming growth factor β 1 (TGF-β1) expression in the liver were performed. We found that ageing and long-term DM1 resulted in a significantly increased expression of CYP24 in hepatocytes, as well as in non-hepatocyte liver cells (Kupffer cells, hepatic stellate cells and sinusoidal endothelial cells). Ageing and long-term DM1 resulted in an increased expression of TGF-β1 as well. Expression of CYP24 coexisted with the expression of TGF-β1 in all types of hepatic cells. We concluded that liver has the capacity for an active vitamin D catabolism in different populations of liver cells, especially in sinusoidal endothelial cells, through an expression of CYP24. That capacity is substantially increased during ageing and long-term diabetes mellitus. Increased liver calcitriol catabolism could be one of the mechanisms of the bone metabolism impairment related to ageing and diabetes.

Association of Circulating 25(OH)D and Lower Urinary Tract Symptoms: A Four-Year Prospective Study among Elderly Chinese Men

The role of vitamin D in relation to lower urinary tract symptoms (LUTS) remains inconclusive. This four-year longitudinal study aims to explore the association of circulating 25(OH)D and LUTS in elderly Chinese men. Two thousand Chinese men aged 65 and older were recruited from a local community, of which 1998 (99.9%) at baseline and 1564 (78.2%) at four-year follow-up reported data on LUTS, and 988 of the randomly chosen subpopulation were assayed for serum 25(OH)D by radioimmunoassay at baseline. LUTS were evaluated by a validated International Prostate Symptoms Scale (IPSS). Data on demographic characteristics, lifestyle factors, health, and medications were collected. Serum parathyroid and sex steroid hormones and genotypes of vitamin D receptors were assayed. The association of serum 25(OH)D and LUTS was examined by using multivariable regression models. Serum 25(OH)D was not significantly associated with the changes of IPSS or the risk of LUTS in overall participants. However, among men with 25(OH)D ≤ 60 nmol/L, each 10 nmol/L increase of 25(OH)D over 0 nmol/L was significantly associated with 1.3 lower points of IPSS or a 51.6% decreased risk for moderate/severe LUTS four years later. Adjustment for serum androstenedione (p = 0.019) and dehydropiandrosterone (p = 0.037) attenuated the associations. Our study suggested that among individuals with low vitamin D status, the increase of the 25(OH)D level may be associated with a lowered risk of LUTS.

Vitamin D and urological cancers

Introduction

Vitamin D controls calcium and phosphate homeostasis. Additionally, it has been proven that vitamin D is an important modulator of cellular differentiation and proliferation in a number of normal and malignant cells. Vitamin D can regulate proliferation, apoptosis, and cell adhesion at the tumor cell level. It also modifies tumor angiogenesis, invasion, and metastasis and also decreases oxidative DNA damage.

Material and methods

The Medline and Web of Science databases were searched without time limit on October 2015 using the terms ‘vitamin D’ in conjunction with ‘kidney cancer’, ‘bladder cancer’, ‘prostate cancer’, and ‘testis cancer’. Autoalerts in Medline were also run and reference lists of original articles, review articles, and book chapters were searched for further eligible articles.

Results

In recent years, vitamin D has received vast attention due to suggestions that it may have a crucial role in the prevention and therapy of various cancers. Many epidemiologic studies have reported the impact of VD3 on preventing several cancers and other pathologies. Assuming that vitamin D status changes cancer risk, enough vitamin D supply would be an easy, economical, and safe cancer incidence and mortality reduction method. However, despite numerous researches, the role of vitamin D in cancer incidence and therapy remains unclear.

Conclusions

The impact of vitamin D is well described in breast, colon, and prostate cancer; yet, there is only little published about other malignancies.

New insights into the androgen biotransformation in prostate cancer: A regulatory network among androgen, androgen receptors and UGTs

Androgen, as one kind of steroid hormones, is pivotal in the hormone-sensitive cancer, such as prostate cancer (PCa). The synthesis, elimination, and bioavailability of androgen in prostate cells have been proved to be a main cause of the carcinogenesis, maintenance and deterioration of PCa. This review illustrates the outlines of androgen biotransformation, and further discusses the different enzymes, especially UDP-glucuronyltransferases (UGTs) embedded in both benign and malignant prostate cells, which catalyze the reactions. Although many inhibitors of the enzymes responsible for the synthesis of androgens have been developed into drugs to fight against PCa, the elimination procedures metabolized by the UGTs are less emphasized. Thus the regulatory network among androgen, androgen receptors (AR) and UGTs is carefully reviewed in this article, indicating the determinant effects of UGTs on prostatic androgens and the regulation of AR. Finally, the hypothesis is also put forward that the regulators of UGTs may be developed to accelerate the androgen elimination and benefit PCa therapy.

Anti-Proliferative and Apoptotic Activities of Müllerian Inhibiting Substance Combined with Calcitriol in Ovarian Cancer Cell Lines

PURPOSE

This study aimed to investigate whether Müllerian inhibiting substance (MIS) in combination with calcitriol modulates proliferation and apoptosis of human ovarian cancer (OCa) cell lines (SKOV3, OVCAR3, and OVCA433) and identify the signaling pathway by which MIS mediates apoptosis.

MATERIALS AND METHODS

OCa cell lines were treated with MIS in the absence or presence of calcitriol. Cell viability and proliferation were evaluated using the Cell Counting Kit-8 assay and apoptosis was evaluated by DNA fragmentation assay. Western blot and enzyme-linked immunosorbent assay were used to determine the signaling pathway.

RESULTS

The cells showed specific staining for the MIS type II receptor. Treatment of OCa cells with MIS and calcitriol led to dose- and time-dependent inhibition of cell growth and survival. The combination treatment significantly suppressed cell growth, down-regulated the expression of B-cell lymphoma 2 (Bcl-2), and up-regulated the expressions of Bcl-2 associated X protein, caspase-3, and caspase-9 through the extracellular signal-regulated kinase signaling pathway.

CONCLUSION

These results, coupled with a much-needed decrease in the toxic side effects of currently employed therapeutic agents, provide a strong rationale for testing the therapeutic potential of MIS, alone or in combination with calcitriol, in the treatment of OCa.

Vitamin D and prostate cancer prognosis: a Mendelian randomization study

PURPOSE

Decreased vitamin D levels have been associated with prostate cancer, but it is unclear whether this association is causal. A functional single-nucleotide polymorphism (SNP) in the group-specific component (GC) gene (T > G, rs2282679) has been associated with 25-hydroxy (25-OH) vitamin D and 1.25 dihydroxy (1.25-OH2) vitamin D levels.

METHODS

To examine the hypothesized inverse relationship between vitamin D status and prostate cancer, we studied the association between this SNP and prostate cancer outcome in the prospective PROCAGENE study comprising 702 prostate cancer patients with a median follow-up of 82 months.

RESULTS

GC rs2282679 genotypes were not associated with biochemical recurrence [hazard ratios (HR) 0.91, 95 % confidence interval (CI) 0.73-1.12; p = 0.36], development of metastases (HR 1.20, 95 % CI 0.88-1.63; p = 0.25) or overall survival (HR 1.10; 95 % CI 0.84-1.43; p = 0.50).

CONCLUSIONS

A causal role of vitamin D status, as reflected by GC rs2282679 genotype, in disease progression and mortality in prostate cancer patients is unlikely.

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 D3 regulates the formation and degradation of gap junctions in androgen-responsive human prostate cancer cells

1α-25(OH)2 vitamin D3 (1-25D), an active hormonal form of Vitamin D3, is a well-known chemopreventive and pro-differentiating agent. It has been shown to inhibit the growth of several prostate cancer cell lines. Gap junctions, formed of proteins called connexins (Cx), are ensembles of cell-cell channels, which permit the exchange of small growth regulatory molecules between adjoining cells. Cell-cell communication mediated by gap junctional channels is an important homeostatic control mechanism for regulating cell growth and differentiation. We have investigated the effect of 1-25D on the formation and degradation of gap junctions in an androgen-responsive prostate cancer cell line, LNCaP, which expresses retrovirally-introduced Cx32. Connexin32 is expressed by the luminal and well-differentiated cells of normal prostate and prostate tumors. Our results document that 1-25D enhances the expression of Cx32 and its subsequent assembly into gap junctions. Our results further show that 1-25D prevents androgen-regulated degradation of Cx32, post-translationally, independent of androgen receptor (AR)-mediated signaling. Finally, our findings document that formation of gap junctions sensitizes Cx32-expressing LNCaP cells to the growth inhibitory effects of 1-25D and alters their morphology. These findings suggest that the growth-inhibitory effects of 1-25D in LNCaP cells may be related to its ability to modulate the assembly of Cx32 into gap junctions.

Role of local bioactivation of vitamin D by CYP27A1 and CYP2R1 in the control of cell growth in normal endometrium and endometrial carcinoma

Vitamin D (VD) deficiency has been suggested as a risk factor for cancer. One recognized mechanism is that the low-serum 25-hydroxyvitamin D (25(OH)D) of VD deficiency reduces intratumoral 25(OH)D conversion to 1α,25-dihydroxyvitamin D (1,25D, the hormonal form of VD), compromising 1,25D-VD receptor (VDR) antitumoral actions. Reduced tumoral VDR and increased CYP24A1, the enzyme that degrades 1,25D and 25(OH)D, further worsen cancer progression. Importantly, in cells expressing CYP27A1 and/or CYP2R1, which convert inert VD into 25(OH)D, low-serum VD may reduce intratumoral 25(OH)D synthesis thereby compromising VDR antitumoral actions because 25(OH)D can activate the VDR directly and enhance 1,25D-VDR action. Therefore, this study examined whether abnormal endometrial expression of CYP27A1 and/or CYP2R1 may impair VDR-antiproliferative properties in endometrial carcinoma (EC). Immunohistochemical analysis of tissue microarrays of normal human endometrium (NE; n=60) and EC (n=157) showed the expected lower VDR expression in EC (P=0.0002). Instead, CYP24A1 expression was lower in EC compared with NE, while CYP27A1 and CYP2R1 expressions were higher (P=0.0002; P=0.03). Furthermore, in NE and EC, CYP2R1 and CYP27A1 expression correlated directly with nuclear VDR levels, an indicator of ligand-induced VDR activation, and inversely with the proliferation marker Ki67. Accordingly, in the endometrioid carcinoma cell lines IK, RL95/2 and HEC1-A, which express VDR, CYP27A1, and CYP2R1, VD efficaciously reduced cell viability and colony number, with a time course that paralleled actual increases in both intracellular 25(OH)D and nuclear VDR levels. Thus, VD may protect from EC progression in part through increased intratumoral 25(OH)D production by CYP27A1 and CYP2R1 for autocrine/paracrine enhancement of 1,25D-VDR-antiproliferative actions.

The tumor suppressor TERE1 (UBIAD1) prenyltransferase regulates the elevated cholesterol phenotype in castration resistant prostate cancer by controlling a program of ligand dependent SXR target genes

Castrate-Resistant Prostate Cancer (CRPC) is characterized by persistent androgen receptor-driven tumor growth in the apparent absence of systemic androgens. Current evidence suggests that CRPC cells can produce their own androgens from endogenous sterol precursors that act in an intracrine manner to stimulate tumor growth. The mechanisms by which CRPC cells become steroidogenic during tumor progression are not well defined. Herein we describe a novel link between the elevated cholesterol phenotype of CRPC and the TERE1 tumor suppressor protein, a prenyltransferase that synthesizes vitamin K-2, which is a potent endogenous ligand for the SXR nuclear hormone receptor. We show that 50% of primary and metastatic prostate cancer specimens exhibit a loss of TERE1 expression and we establish a correlation between TERE1 expression and cholesterol in the LnCaP-C81 steroidogenic cell model of the CRPC. LnCaP-C81 cells also lack TERE1 protein, and show elevated cholesterol synthetic rates, higher steady state levels of cholesterol, and increased expression of enzymes in the de novo cholesterol biosynthetic pathways than the non-steroidogenic prostate cancer cells. C81 cells also show decreased expression of the SXR nuclear hormone receptor and a panel of directly regulated SXR target genes that govern cholesterol efflux and steroid catabolism. Thus, a combination of increased synthesis, along with decreased efflux and catabolism likely underlies the CRPC phenotype: SXR might coordinately regulate this phenotype. Moreover, TERE1 controls synthesis of vitamin K-2, which is a potent endogenous ligand for SXR activation, strongly suggesting a link between TERE1 levels, K-2 synthesis and SXR target gene regulation. We demonstrate that following ectopic TERE1 expression or induction of endogenous TERE1, the elevated cholesterol levels in C81 cells are reduced. Moreover, reconstitution of TERE1 expression in C81 cells reactivates SXR and switches on a suite of SXR target genes that coordinately promote both cholesterol efflux and androgen catabolism. Thus, loss of TERE1 during tumor progression reduces K-2 levels resulting in reduced transcription of SXR target genes. We propose that TERE1 controls the CPRC phenotype by regulating the endogenous levels of Vitamin K-2 and hence the transcriptional control of a suite of steroidogenic genes via the SXR receptor. These data implicate the TERE1 protein as a previously unrecognized link affecting cholesterol and androgen accumulation that could govern acquisition of the CRPC phenotype.

Pharmacogenetics of the nuclear hormone receptors: the missing link between environment and drug effects?

In the last decade, genetic variations in ABC/SLC transporters and phase I/II enzymes have raised pharmacogenetic markers as being predictive to the attention of researchers in the field of personalized medicine in oncology. However, it is becoming evident that the sequence variations in these genes cannot address by themselves the sharp interindividual variability in drug effects. Recently, nuclear receptors (NRs), including pregnane X receptor, constitutive androstane receptor, retinoid X receptor, farnesoid X receptor, liver X receptor, vitamin D receptor, peroxisome proliferator-activated receptors and HNF4A, have demonstrated key roles in regulating transporter and metabolic gene expression in response to xeno/endobiotics, as well as antineoplastic drugs. These findings attracted interest to the genetics of the NRs for their possible role in influencing the metabolism and pharmacological profiles of chemotherapeutics. In this review, we aim to summarize the most recent findings in the innovative field of NR pharmacogenetics and findings in how they could integrate with more traditional markers in order to improve drug treatment personalization.

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

We have synthesized 39 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] analogs having two side chains attached to carbon-20 (Gemini) with various modifications and compared their anticancer activities. Five structure-function rules emerged to identify analogs with enhanced anticancer activity. One of these active analogs, BXL-01-0126, was more potent than 1,25(OH)2D3 in mediating 50% clonal inhibition of cancer cell growth. Murine studies found that BXL-01-0126 and 1,25(OH)2D3 had nearly the same potency to raise serum calcium levels. Taken together, BXL-01-0126 when compared to 1,25(OH)2D3 has greater anticancer potency, but similar toxicity causing hypercalcemia. We focused on the effect of these compounds on the stimulation of expression of human cathelicidin antimicrobial peptide (CAMP) whose gene has a vitamin D response element in its promoter. Expression of CAMP mRNA and protein increased in a dose-response fashion after exposure of acute myeloid leukemia (AML) cells to the Gemini analog, BXL-01-126, in vitro. A xenograft model of AML was developed using U937 AML cells injected into NSG-immunodeficient mice. Administration of vitamin D3 compounds to these mice resulted in substantial levels of CAMP in the systemic circulation. This suggests a unique prophylactic treatment at diagnosis or during induction chemotherapy for AML patients to provide them with protection against various microbial infections through CAMP induction.

The world pandemic of vitamin D deficiency could possibly be explained by cellular inflammatory response activity induced by the renin-angiotensin system

This review attempts to show that there may be a relationship between inflammatory processes induced by chronic overstimulation of the renin-angiotensin system (RAS) and the worldwide deficiency of vitamin D (VitD) and that both disorders are probably associated with environmental factors. Low VitD levels represent a risk factor for several apparently different diseases, such as infectious, autoimmune, neurodegenerative, and cardiovascular diseases, as well as diabetes, osteoporosis, and cancer. Moreover, VitD insufficiency seems to predispose to hypertension, metabolic syndrome, left ventricular hypertrophy, heart failure, and chronic vascular inflammation. On the other hand, inappropriate stimulation of the RAS has also been associated with the pathogenesis of hypertension, heart attack, stroke, and hypertrophy of the left ventricle and vascular smooth muscle cells. Because VitD receptors (VDRs) and RAS receptors are almost distributed in the same tissues, a possible link between VitD and the RAS is even more plausible. Furthermore, from an evolutionary point of view, both systems were developed simultaneously, actively participating in the regulation of inflammatory and immunological mechanisms. Changes in RAS activity and activation of the VDR seem to be inversely related; thus any changes in one of these systems would have a completely opposite effect on the other, making it possible to speculate that the two systems could have a feedback relationship. In fact, the pandemic of VitD deficiency could be the other face of increased RAS activity, which probably causes lower activity or lower levels of VitD. Finally, from a therapeutic point of view, the combination of RAS blockade and VDR stimulation appears to be more effective than either RAS blockade or VDR stimulation individually.

Combination of calcitriol and dietary soy exhibits enhanced anticancer activity and increased hypercalcemic toxicity in a mouse xenograft model of prostate cancer

BACKGROUND

The potential role of vitamin D and soy in prostate cancer (PCa) prevention/treatment has gained much attention in recent years. In this study, we evaluated the anticancer activity of calcitriol, the active form of vitamin D, dietary soy, and their combinations in a mouse model of PCa.

METHODS

Athymic male nude mice bearing PC-3 human PCa xenografts received diets containing 10 or 20 kcal% soy, calcitriol injections, or a combination of dietary soy and calcitriol. Changes in tumor growth, serum levels of 1,25(OH)(2)D and calcium, and regulation of tumor gene expression were examined.

RESULTS

The combination treatments resulted in substantially greater inhibition of tumor growth than either agent alone. Soy diets alone caused a modest elevation in serum 1,25(OH)(2)D, whereas the calcitriol-soy combinations led to substantially elevated serum 1,25(OH)(2) D, hypercalcemia, and in some cases lethal toxicity. The combinations enhanced calcitriol activity in regulating target gene expression, including greater up-regulation of anti-proliferative (p21, IGFBP-3) and pro-apoptotic (Bax) genes, increased inhibition of anti-apoptotic (Bcl-2) and cell cycle promoting (cyclin D1) genes, and suppression of prostaglandin (PG) synthesis and signaling (COX-2, 15-PGDH, PG receptors). Increases in serum calcium were accompanied by elevated expression of intestinal calcium absorption genes (TRPV6, calbindin-9k).

CONCLUSIONS

Soy increases the bioavailability of endogenous and administered calcitriol, thereby enhancing its anticancer effects and risk of hypercalcemia. Since both agents are easily available as dietary supplements, the increased potential for hypercalcemic toxicity becomes an important factor when considering the combined use of vitamin D and soy in PCa therapy.

Advanced prostate cancer--a case for adjuvant differentiation therapy

The development of novel therapies such as abiraterone acetate and sipuleucel-T has improved the outlook for patients with advanced-stage and castration-resistant prostate cancer. However, the beneficial effects of these drugs are only measured in months. Moreover, the National Institute for Health and Clinical Excellence in the UK had ruled that the use of abiraterone acetate was not cost-effective before cost revision by the manufacturers. The FDA statement asserting that the use of 5α-reductase inhibitors for prostate cancer chemoprevention could increase the risk of developing high-grade prostate cancer also indirectly questions the value of direct androgen response manipulation for long-term benefit. These reports illustrate the need for a fresh and comprehensive analysis of advanced prostate cancer pathology to promote the next generation of effective adjuvant therapies. One such avenue is that of differentiation therapy, which seeks to promote the differentiation of cancer stem cells into a phenotype more sensitive to anticancer therapy than their parents. Using differentiation therapy with current antiandrogen therapies should augment our armoury of treatment for the management of advanced prostate cancer.

Review article: vitamin D and inflammatory bowel disease--established concepts and future directions

BACKGROUND

Understanding of the role of vitamin D in health and disease has increased markedly in the past decade, with its involvement extending well beyond traditional roles in calcium and phosphate homeostasis and musculoskeletal health. This conceptual expansion has been underpinned by identification and exploration of components of this axis including vitamin D-binding protein, key enzymes and receptors in multiple cell types, and a greater recognition of nonclassical autocrine and paracrine effects. Its influence in IBD remains uncertain.

AIM

To review the role of vitamin D in bone health, immune regulation and cancer prevention in IBD, and to outline practical issues and limitations of its use.

METHODS

An extensive online literature review including PubMed and Medline.

RESULTS

In patients with IBD, the vitamin D axis provides an important and often underutilised pathway to preserving bone health. Furthermore, an exciting body of clinical and basic science research demonstrates that these pathways may have an integral part to play in regulation of the immune response in IBD, through effects on the intestinal barrier, antigen presenting cells and adaptive T cells. The possibility of chemoprevention requires further study. The optimal target level of 25-hydroxy vitamin D in patients with IBD is currently uncertain, as is the best therapeutic modality.

CONCLUSIONS

Study of vitamin D pathways may result in the development of relatively inexpensive therapeutic options to optimise patient outcomes. Further prospective clinical research is required to address efficacy and long-term safety.