Novel pathways that contribute to the anti-proliferative and chemopreventive activities of calcitriol in prostate cancer

Identification of a functional vitamin D response element in the promoter of goose anti-Müllerian hormone gene

Anti-Müllerian hormone (AMH) plays an important role in avian ovarian follicle development. The high mRNA expression of AMH in avian ovarian prehierarchical follicles helps prevent premature granulosa cell differentiation. Vitamin D3 was reported to downregulate AMH mRNA expression in granulosa cells of prehierarchical follicles in hens; however, the underlying molecular mechanism remains unknown. In this study, AMH mRNA expression was investigated in granulosa cells of prehierarchical follicles in geese under vitamin D3 induction. A potential vitamin D response element (VDRE) present in the goose AMH promoter was identified using luciferase activity, electrophoretic mobility shift assay (EMSA), and chromatin immunoprecipitation (ChIP) assays. The results showed that AMH mRNA expressions were downregulated by vitamin D3 in granulosa cells of prehierarchical follicles in geese. A classical VDRE-like sequence was identified in the goose AMH promoter by in silico analyses. Luciferase activity assays revealed that the putative VDRE is a negative regulatory element. Vitamin D receptor (VDR) and retinoic X receptor (RXR) are necessary to decrease the AMH promoter activity induced by vitamin D3. The EMSA and ChIP assays demonstrated that the VDR/RXR complex directly binds to the putative VDRE. These results suggest that vitamin D3 downregulates AMH mRNA expression via a functional VDRE that binds the VDR/RXR heterodimer in goose ovarian prehierarchical follicles. These results provide new insights into the regulatory mechanisms of vitamin D3 in avian ovarian follicular development.

Vitamin D and biomarkers of inflammation and oxidative stress among pregnant women: a systematic review of observational studies

OBJECTIVE

This systematic review aimed to map the evidence evaluated the relationship between vitamin D and redox and inflammatory status during gestation.

METHODS

Three databases (PubMed/MEDLINE, Scopus, and Web of Science (WoS)) and reference list of included documents were searched for related observational studies published until 2nd October 2023. To determine the quality of the selected observational studies, the Newcastle-Ottawa Scale (NOS) was used.

RESULTS

After a primary search of three databases, 19492records were appeared. When duplicates and irrelevant documents were removed, 14 articles were found to have eligible criteria. The design of the identified studies was cross-sectional, case-control and cohort. Evidence showed an adverse association between 25(OH)D and the biomarkers of inflammation, such as high-sensitivity C-reactive protein (hs-CRP), Interleukin-1beta (IL-1β), Interleukin-6 (IL-6), and tumor necrosis factor- alfa (TNF-α) during pregnancy. On the contrary, some studies represented that 25(OH)D positively correlated with hs-CRP in the cord blood. One study suggested a direct association between serum concentrations of 25(OH)D and Interleukin-8 (IL-8), macrophage inflammatory protein (MIP), and TNF-α levels in mothers with gestational diabetes mellitus (GDM). A case-control study showed that lower serum concentration of 25(OH)D positively correlated with total antioxidant capacity (TAC) levels in participants.

CONCLUSIONS

Evidence confirmed the supposition of the direct relationship between vitamin D levels and biomarkers with anti-inflammatory and anti-oxidative properties. However, the Existence of inconsistent evidence confirms the need for further studies in mothers with GDM and hypertensive disorders.

PROSPERO REGISTRATION CODE

CRD42020202600.

Seasonal dynamic of cholecalciferol (D3) and anti-Muellerian hormone (AMH) with impact on ovarian response and IVF/ICSI

OBJECTIVE

Recent studies revealed intriguing associations between cholecalciferol (D3) and reproductive functions. Seasonal changes of D3 concentrations are well known; however, they are not always considered in the context of reproductive functions. In this study, we analyzed D3 serum concentration in IVF/ICSI patients with respect to seasonal 3-month quartiles and anti-Muellerian hormone (AMH) referring to the impact on Assisted Reproductive Technologies (ART) outcome.

MATERIALS AND RESEARCH METHODS

We studied 469 female patients, presenting between 2012 and 2018 for ART treatment in our fertility center. D3 as well as the AMH serum concentrations were measured at the beginning of the follicle stimulation (days 3-5 of menstrual cycles). Results were evaluated with respect to seasonal quartiles and outcome of the ART cycles.

RESULTS

D3 concentrations showed significant fluctuations within annual quartiles with a pronounced peak in August-October and a minimum in February-April (26.0 vs. 20.5 mg/dl; p < 0.0001). Similar seasonal dynamics were found for AMH (2.98 vs. 1.78 ng/ml; p = 0.010) and these were associated with significantly shorter stimulation periods during August-October (11.29 vs. 12.12 days; p = 0.042), higher number of fertilized oocytes between August and October (6.23 vs. 4.97; p = 0.05) along with a trend towards higher numbers of cumulus-oocyte complexes. However, no such differences were found for the numbers of MII oocytes or pregnancy rates.

CONCLUSION

Our data indicate seasonal 3-month quartile variations of AMH concentrations and characteristics of ART, such as days of ovarian stimulation and number of fertilized oocytes. Highest AMH concentrations were found between August and October and this quartile was associated with highest D3 concentrations.

A systematic review and meta-analysis of the association between vitamin D and ovarian reserve

It is hypothesized that vitamin D deficiency could be related to ovarian reserve. This systematic review and meta-analysis was undertaken to analyze the possible association between vitamin D and ovarian reserve among adolescent and adult women. All eligible studies identified through the ISI Web of Science, PubMed, and Scopus were included up to May 2021. A random-effects meta-analysis model was implemented and a weighted mean difference (WMD) and 95% confidence interval (CI) were calculated. A total of 38 papers covering 8608 individuals were enrolled in this systematic review and meta-analysis. Antral follicle count (AFC) was significantly lower among Asians (WMD - 0.65; 95% CI - 1.28 to - 0.01; P = 0.04; I2 = 0.0%) and luteinizing hormone (LH) levels were higher in non-Asians (WMD 2.16 IU/L; 95% CI 0.20 to 4.12; P = 0.031; I2 = 9.3%) with vitamin D insufficiency/deficiency. Also, there was a negative correlation between vitamin D and LH/FSH ratio in women with normal body mass index (BMI) (Fisher's Z: - 0.18; 95% CI - 0.37 to - 0.008; P = 0.041; I2 = 51.5%). Although there were no significant associations between serum vitamin D levels and any of the intended ovarian reserve markers, subgroup analyses have found significant findings regarding AFC, LH, and LH/FSH ratio. In order to understand the underlying mechanisms of vitamin D in female reproduction, further attempts are needed.

A Narrative Review of Current Understanding of the Pathophysiology of Polycystic Ovary Syndrome: Focus on Plausible Relevance of Vitamin D

Polycystic ovarian syndrome (PCOS) is the most prevalent endocrinopathy of reproductive years. Salient features in presentation of patients PCOS include menstrual dysfunction, hyperandrogenism and/or polycystic appearance of ovaries on ultrasound. While the diagnosis of PCOS depends on presence of specified criteria, misdiagnoses are common. Despite years of extensive research, the exact aetiology of PCOS remains largely unknown. In the past decade, apart from insulin resistance and hyperandrogenemia, anti-mullerian hormone (AMH), an important marker of ovarian reserve, and vascular endothelial growth factor (VEGF), a crucial factor in angiogenesis, have been examined as plausible players of causative relevance for PCOS. Vitamin D, a sex-steroid hormone that is universally known for its relevance for skeletal health, has received increasing attention due to growing evidence supporting its pivotal in reproductive physiology and in PCOS. In this review we summarize our current understanding of the mechanisms relevant to the pathophysiology of PCOS and examine the role of vitamin D signalling in this context.

Anti-Müllerian Hormone and Ovarian Reserve: Update on Assessing Ovarian Function

CONTEXT

Anti-müllerian hormone (AMH) is produced by granulosa cells of small, growing follicles in the ovary. Serum AMH levels strongly correlate with the number of growing follicles, and therefore AMH has received increasing attention as a marker for ovarian reserve. This review summarizes recent findings and limitations in the application of serum AMH in ovarian reserve assessment.

EVIDENCE ACQUISITION

A PubMed search was conducted to find recent literature on the measurements and use of serum AMH as a marker for ovarian reserve.

EVIDENCE SYNTHESIS

Serum AMH levels are measured to assess the "functional ovarian reserve," a term that is preferred over "ovarian reserve," since AMH levels reflect the pool of growing follicles that potentially can ovulate. Serum AMH levels are used in individualized follicle-stimulating hormone dosing protocols and may predict the risk of poor response or ovarian hyperstimulation syndrome but has limited value in predicting ongoing pregnancy. Serum AMH levels are studied to predict natural or disease-related age of menopause. Studies show that the age-dependent decline rates of AMH vary among women. The generalized implementation of serum AMH measurement has also led to an increase in diagnostic assays, including automated assays. However, direct comparison of results remains problematic.

CONCLUSION

Serum AMH remains the preferred ovarian reserve marker. However, the lack of an international standard for AMH limits comparison between AMH assays. Furthermore, little is known about endogenous and exogenous factors that influence serum AMH levels, which limits proper interpretation of AMH values in a clinical setting.

The Association between Vitamin D and Anti-Müllerian Hormone: A Systematic Review and Meta-Analysis

Accumulating evidence from animal and human studies indicates a role for vitamin D in female reproductive physiology, and numerous clinical studies have suggested its potential benefit for various aspects of human reproduction. Anti-Müllerian hormone (AMH) is an ovarian biomarker that plays an important role in folliculogenesis. It is the most sensitive ovarian reserve marker and is widely used clinically in reproductive medicine. While initial studies have suggested that vitamin D may be associated with ovarian reserve markers, including AMH, evidence has been conflicting. Currently, there is considerable debate in the field whether vitamin D has the capacity to influence ovarian reserve, as indicated by the AMH level. The current systematic review aims to evaluate and summarize the available evidence regarding the relationship between vitamin D and AMH. In total, 18 observational studies and 6 interventional studies were included in this systematic review. Cross-sectional studies have reported largely discrepant findings regarding an association between serum vitamin D and AMH levels, which are likely due to the heterogeneity in study populations, as well as the apparently complex relationship that may exist between vitamin D and AMH. However, meta-analysis of interventional studies performed herein that examined the effects of vitamin D supplementation on serum AMH levels indicates a cause-effect relationship between vitamin D and AMH, the direction of which appears to depend on a woman’s ovulatory status. Serum AMH was significantly decreased following vitamin D supplementation in polycystic ovarian syndrome (PCOS) women (standardized mean difference (SMD) −0.53, 95% CI −0.91 to −0.15, p < 0.007), while it was significantly increased following vitamin D supplementation in ovulatory women without PCOS (SMD 0.49, 95% CI 0.17 to 0.80, p = 0.003). In conclusion, the results of this systematic review demonstrate that the relationship between vitamin D and AMH is a complex one, and large, randomized trials of vitamin D supplementation focusing on different vitamin D status ranges are necessary to gain more insight into the nature of this relationship and the potential benefit of vitamin D to female reproduction in general.

Effects of Vitamin D Supplementation on Inflammation, Colonic Cell Kinetics, and Microbiota in Colitis: A Review

Vitamin D is widely known to regulate bone health, but there is increasing evidence that it may also ameliorate colitis through inflammation, cell proliferation and apoptosis, and the microbiota. The purpose of this review is to systematically examine the mechanisms by which vitamin D reduces colitis. PubMed and Web of Science were searched for articles published between 2008 and 2019 using key words such as "vitamin D," "colitis," "inflammatory bowel disease," "inflammation," "apoptosis," "cell proliferation," and "gut bacteria". Retrieved articles were further narrowed and it was determined whether their title and abstracts contained terminology pertaining to vitamin D in relation to colitis in human clinical trials, animal studies, and cell culture/biopsy studies, as well as selecting the best match sorting option in relation to the research question. In total, 30 studies met the established criteria. Studies consistently reported results showing that vitamin D supplementation can downregulate inflammatory pathways of COX-2, TNF-α, NF-κB, and MAPK, modify cell kinetics, and alter gut microbiome, all of which contribute to an improved state of colitis. Although vitamin D and vitamin D analogs have demonstrated positive effects against colitis, more randomized, controlled human clinical trials are needed to determine the value of vitamin D as a therapeutic agent in the treatment of colitis.

Roles of Vitamin D in Reproductive Systems and Assisted Reproductive Technology

Vitamin D, an essential steroid hormone in the human body, plays an important role in not only the regulation of calcium and phosphorus metabolism, but also in various physiological processes, such as cell differentiation and apoptosis, inflammation, and insulin resistance. Vitamin D receptors are widely distributed in male and female reproductive systems, suggesting that vitamin D is essential for fertility. Because vitamin D deficiency is highly prevalent around the world, this review aims to discuss the potential functions of vitamin D in male and female reproductive systems and the associations between vitamin D and assisted reproductive technology (ART) outcomes. Vitamin D is involved in many physiological reproductive processes, including steroidogenesis, spermatogenesis, and acrosome reaction. It is correlated with sperm quality, ovarian reserve, polycystic ovarian syndrome, and endometriosis, among others. Controversial clinical findings on vitamin D levels and ART outcomes were revealed in this review, and demonstrations of efficacy for human fertility in randomized controlled trials of vitamin D supplementation are notably lacking. Thus, further studies are highly required involving molecular mechanisms among different species and human populations, as well as randomized controlled trials.

Anti-Müllerian hormone level is associated with vitamin D receptor polymorphisms in women with polycystic ovary syndrome

Objective

Our study aimed to investigate the relationship between polymorphisms (Apa1, Bsm1, Fok1, and Cdx2) in the VDR gene as well as AMH and AMHR2 genes and their influence on AMH and 25(OH)D levels in PCOS women.

Study design

Seventy-five patients with PCOS and 23 control women were included. Serum AMH and 25(OH)D levels in patients and controls were measured by enzyme-linked immunosorbent assay (ELISA). Polymorphisms in VDR gene Fok1 C/T (rs2228587), Bsm1 A/G (rs1544410), Apa1 A/C (rs7975232), and Cdx2 A/G (rs11568820) polymorphisms as well as AMH G/T (rs10407022) and AMHR2 A/G (rs2002555) were analyzed using real-time PCR.

Results

Analysis of the VDR Cdx2 polymorphism showed a significantly higher frequency of the homozygous GG (mutant) genotype in the PCOS group as compared with the control group (p < 0.05). The analysis revealed a statistically significant correlation between the presence of FokI and ApaI polymorphisms and AMH levels in PCOS women (p < 0.05). The presence of mutant genotypes (CT, TT) in the Fok1 and (CA, CC) in the Apa1 polymorphisms were associated with higher AMH level in PCOS women (p < 0.05). No statistically significant correlations between AMH and AMHR2 polymorphisms and AMH level were found. Moreover, there was no correlation between AMH and 25(OH)D levels in the PCOS or in the control group.

Conclusion

It seems that the elevated AMH level is associated with VDR Fokl and Apal polymorphisms, but not with 25(OH)D levels in PCOS women. Further research is needed to determine the role of VDR polymorphism in AMH level in PCOS.

Independent association of serum vitamin D with anti-Mullerian hormone levels in women with polycystic ovary syndrome

OBJECTIVE

This study aimed at investigating the association of serum vitamin D (25(OH)D) and anti-Mullerian hormone (AMH) levels in women with polycystic ovary syndrome (PCOS) as well as non-PCOS healthy ovulatory women and the possible confounding effects of adiposity and androgen.

METHOD

This was a cross-sectional study conducted on serum samples collected from 451 women diagnosed with PCOS as well as 244 age-matched healthy ovulatory women in a tertiary gynaecology out-patient clinic and a family planning clinic.

RESULTS

Serum 25(OH)D level was significantly higher in women recruited during summer and autumn than those recruited in winter and spring. Both serum 25(OH)D and AMH levels peaked during summer in women with PCOS. In ovulatory women, only serum 25(OH)D but not AMH level showed such seasonal variation. Serum 25(OH)D level in women with PCOS significantly correlated positively with AMH, AMH/antral follicle count (AFC) ratio, serum total testosterone, sex-hormone-binding globulin and quantitative insulin-sensitivity check index and inversely with body mass index (BMI), insulin, triglycerides and homeostatic model assessment of insulin resistance. After controlling for BMI, 25(OH)D level remained significantly correlated positively with serum AMH, AMH/AFC and total testosterone, and inversely with triglycerides. 25(OH)D level was an independent predictor of serum AMH level after controlling for age, BMI and free androgen index in women with PCOS.

CONCLUSION

Serum 25(OH)D level is an independent factor significantly associated with AMH level in women with PCOS but not in ovulatory women.

Vitamin D Status Is Not Associated with Risk of Early Menopause

Background

Early natural menopause, the cessation of ovarian function before age 45 y, is positively associated with cardiovascular disease and other conditions. Dietary vitamin D intake has been inversely associated with early menopause; however, no previous studies have evaluated risk with regard to plasma 25-hydroxyvitamin D [25(OH)D] concentrations.

Objective

We prospectively evaluated associations of total and free 25(OH)D and vitamin D-binding protein (VDBP) concentrations and the risk of early menopause in a case-control study nested within the Nurses' Health Study II (NHS2). We also considered associations of 25(OH)D and VDBP with anti-Müllerian hormone (AMH) concentrations.

Methods

The NHS2 is a prospective study in 116,430 nurses, aged 25-42 y at baseline (1989). Premenopausal plasma blood samples were collected between 1996 and 1999, from which total 25(OH)D and VDBP concentrations were measured and free 25(OH)D concentrations were calculated. Cases experienced menopause between blood collection and age 45 y (n = 328) and were matched 1:1 by age and other factors to controls who experienced menopause after age 48 y (n = 328). Conditional logistic regression models were used to estimate ORs and 95% CIs for early menopause according to each biomarker. Generalized linear models were used to estimate AMH geometric means according to each biomarker.

Results

After adjusting for smoking and other factors, total and free 25(OH)D were not associated with early menopause. Quartile 4 compared with quartile 1 ORs were 1.04 (95% CI: 0.60, 1.81) for total 25(OH)D and 0.70 (95% CI: 0.41, 1.20) for free 25(OH)D. 25(OH)D was unrelated to AMH concentrations. VDBP was positively associated with early menopause; the OR comparing the highest with the lowest quartile of VDBP was 1.80 (95% CI: 1.09, 2.98).

Conclusions

Our findings suggest that total and free 25(OH)D are not importantly related to the risk of early menopause. VDBP may be associated with increased risk, but replication is warranted.

Combined effects of aspirin and vitamin D3 on two OSCC cell lines: a preliminary study

OBJECTIVES

We evaluated the potential effects of aspirin combined with vitamin D3 on cell proliferation and apoptosis in oral cancer cells.

RESULTS

Compared to the untreated control or individual drug, the combinations of aspirin and vitamin D3 significantly decreased the rates of cell proliferation by CCK-8 assay, and caused higher rates of cell apoptosis in both CAL-27 and SCC-15 cells by Annexin V-FITC apoptosis assay and flow cytometry. Remarkably, the combined treatment with aspirin and vitamin D3 significantly suppressed the expression of Bcl-2 protein and p-Erk1/2 protein, examined by western blot analysis.

CONCLUSIONS

Our study demonstrates that aspirin and vitamin D3 have biological activity against two human OSCC cell lines and their activity is synergistic or additive when two drugs used in combination with therapeutic concentrations. The combination of aspirin and vitamin D3 may be an effective approach for inducing cell death in OSCC.

Shedding new light on female fertility: The role of vitamin D

In the last decades several studies suggested that vitamin D is involved in the modulation of the reproductive process in women due to the expression of VDR and 1α-hydroxylase in reproductive tissues such as ovary, uterus, placenta, pituitary and hypothalamus. Vitamin D has also a role in the regulation of sex hormone steroidogenesis. Increasing evidence suggests that vitamin D might have a regulatory role in polycystic ovary syndrome (PCOS)-associated symptoms, including ovulatory dysfunction, insulin resistance and hyperandrogenism. Vitamin D deficiency also has been reported to contribute to the pathogenesis of endometriosis due to its immunomodulatory and anti-inflammatory properties. Although most of the studies supported a role of vitamin D in the onset of these diseases, randomized controlled trials to assess the efficacy of vitamin D supplementation have never been performed. In this review we critically discuss the role of vitamin D in female fertility, starting from in vitro and in vivo studies, focusing our attention on the two most frequent causes of female infertility: PCOS and endometriosis.

To Study the Vitamin D Levels in Infertile Females and Correlation of Vitamin D Deficiency with AMH Levels in Comparison to Fertile Females

Context:

Human and animal data suggest that low vitamin D (25-hydroxyvitamin D) status is associated with impaired fertility, endometriosis, and polycystic ovary syndrome. Vitamin D regulates antimullerian hormone (AMH), FSH, mRNA, and expression of genes in reproductive tissues, implicating a role in female reproduction.

Aims:

To study the vitamin D levels in infertile females and to know the correlation of vitamin D deficiency (VDD) with serum AMH in infertile females compare to fertile females.

Settings And Design:

This prospective study was conducted in department of Maternal and Reproductive Health in between April 2014 and April 2016.

Materials and Methods:

After matching inclusion and exclusion criteria out of total 70 infertile females, 45 were found to have VDD. Of these 35 patients were identified as cases; in whom, the AMH levels were assessed. As control 35 fertile normal females were taken, in which vitamin D and AMH were taken. In both groups, correlation of VDD with AMH was studied.

Statistical Analysis Used:

To analyze the correlation between vitamin D and AMH linear regression test and for comparison of both the groups, two sample t tests were used.

Results:

The VDD was present in 64.28% of infertile females. In vitamin D deficient cases, the mean for vitamin D was 6.18 ± 2.09 and AMH was 1.94 ± 1.30. In vitamin D deficient controls, the mean for vitamin D was 4.85 ± 3.02 and AMH was 3.47 ± 2.59. On comparison, the vitamin D levels were lower in fertile than infertile females, which was significant (P = 0.04), and AMH levels were lower in cases than control group (P = 0.003).

Conclusion:

The VDD was present in 64.28% of infertile females. No significant correlation was found in between VDD and AMH levels in both the groups.

Direct vitamin D3 actions on rhesus macaque follicles in three-dimensional culture: assessment of follicle survival, growth, steroid, and antimüllerian hormone production

OBJECTIVE

To investigate the direct actions of active 1,25-dihydroxy vitamin D3 (VD3) upon primate follicular development at specific stages of folliculogenesis.

DESIGN

Secondary preantral follicles were isolated from rhesus monkeys ovaries, encapsulated in alginate, and cultured for 40 days. Follicles were randomly assigned to experimental groups of control, low-dose VD3 (LVD3; 25 pg/mL), and high-dose VD3 (HVD3; 100 pg/mL).

SETTING

National primate research center.

ANIMAL(S)

Adult, female rhesus macaques (Macaca mulatta).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Follicle survival and growth, as well as oocyte size, were assessed. Progesterone (P₄), androstenedione (A₄), E₂, and antimüllerian hormone (AMH) concentrations in culture media were measured.

RESULT(S)

Compared with the control group, LVD3 increased preantral follicle survival at week 2 by >66%, while HVD3 increased antral follicle diameters at week 5. Follicles with diameters ≥500 μm at week 5 were categorized as fast-growing follicles. Higher percentages of fast-growing follicles were obtained after HVD3 treatment. Although P₄, A₄, and E₂ production by antral follicles was not altered by VD3, AMH concentrations were 36% higher in the LVD3 group relative to controls at week 5. Oocytes with larger diameters were retrieved from antral follicles developed in both LVD3 and HVD3 groups compared with controls.

CONCLUSION(S)

The addition of LVD3 increased preantral follicle survival and maintained AMH production by antral follicles, while HVD3 improved antral follicle growth. VD3 supplement promoted oocyte growth in in vitro-developed follicles. Direct actions of VD3 on the primate follicle appear to be both dose and stage dependent.

The role of AMH in the pathophysiology of polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) affects 5 - 10% of reproductive age women, but its pathogenesis is still poorly understood. The aim of this review is to collate evidence and summarize our current knowledge of the role of anti-Müllerian hormone (AMH) in PCOS pathogenesis. AMH is increased and correlated with the various reproductive and metabolic/endocrine alterations in PCOS. AMH plays an inhibitory role in follicular development and recruitment, contributing to follicular arrest. AMH inhibitory action on FSH-induced aromatase production likely contributes to hyperandrogenism in PCOS, which further enhances insulin resistance in these women. Elevated serum AMH concentrations are predictive of poor response to various treatments of PCOS including weight loss, ovulation induction and laparoscopic ovarian drilling, while improvement in various clinical parameters following treatment is associated with serum AMH decline, further supporting an important role for AMH in the pathophysiology of this syndrome. This review emphasizes the need for understanding the exact mechanism of action of AMH in the pathophysiology of PCOS. This may lead to the development of new treatment modalities targeting AMH to treat PCOS, as well as help clinicians in prognostication and better tailoring existing treatments for this disease.

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.

Role of vitamin D in female reproduction

Vitamin D is a fat-soluble vitamin that belongs to the family of steroid hormones. The biological actions of vitamin D are exerted through a soluble protein, the vitamin D receptor (VDR). VDR is a transcription factor located in the nuclei of target cells that mediates the genomic action of the active form of vitamin D (1,25(OH)2D3). This transcription factor is distributed in various tissues, including the reproductive system. The presence of VDR in female reproductive tissue suggests that vitamin D is involved in female reproduction. The present article reviews the impact of vitamin D on anti-Müllerian hormone (AMH), as an ovarian reserve marker, and ovarian steroidogenesis. This article also discusses the impact of vitamin D as a factor that influences infertility and the outcome of in vitro fertilization (IVF), insulin resistance (IR), hyperandrogenism, endometriosis and polycystic ovary syndrome (PCOS).

Vitamin D in Prostate Cancer

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

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.

Association between sex steroids, ovarian reserve, and vitamin D levels in healthy nonobese women

CONTEXT

Vitamin D maintains calcium and phosphorous homeostasis and promotes bone mineralization; however, its nonskeletal functions are increasingly being recognized. Recent evidence supports a role for vitamin D in reproductive potential, but few studies have investigated the potential effects of vitamin D on reproductive hormone biosynthesis and ovarian reserve.

OBJECTIVE

The aim of this study was to determine the relationships between the serum level of vitamin D, reproductive hormone levels, and ovarian reserve in healthy nonobese women.

DESIGN

This was a cross-sectional study.

SETTING

The study was performed at the Fertility Center at CHA Medical Center.

PARTICIPANTS

Seventy-three healthy women volunteers participated in this study. The participants were nonobese parous women with regular menstrual cycles and no history of infertility.

MAIN OUTCOME MEASURES

We determined serum levels of vitamin D, steroid hormones, SHBG, ovarian reserve markers, homeostatic model assessment of insulin resistance index, and lipid profiles.

RESULTS

In linear regression analysis adjusting for age, body mass index, homeostatic model assessment of insulin resistance, and lipid profile, serum vitamin D level positively correlated with total T (P < .001) and free androgen index (P < .001) but did not correlate with dehydroepiandrosterone sulfate or other steroid hormones. The spline regression-suggested relationship between 25-hydroxyvitamin D and total T was most pronounced at a 25-hydroxyvitamin D concentration greater than 13 ng/mL (β-coefficient 2.374, 95% confidence interval 1.435-3.313). The serum vitamin D level was not associated with the levels of ovarian reserve markers.

CONCLUSION

Our study revealed a positive correlation between serum vitamin D level and T level in healthy nonobese women, suggesting that vitamin D may increase fertility through the modulation of androgen activity. The possible causality of the relationship between vitamin D and T deserves further investigation.

Role of vitamin D in ovarian physiology and its implication in reproduction: a systematic review

OBJECTIVE

To report an update on the role of vitamin D (VD) in ovarian physiology with a focus on genes involved in steroidogenesis, follicular development, and ovarian reserve, as well as ovulatory dysfunction associated with polycystic ovary syndrome (PCOS), and ovarian response to assisted reproductive technology (ART).

DESIGN

Systematic review.

SETTING

Not applicable.

PATIENT(S)

Human, animal, and cell culture models.

INTERVENTION(S)

Pubmed literature search.

MAIN OUTCOME MEASURE(S)

Granulosa cell function, serum antimüllerian hormone (AMH), AMH and its receptor gene expression, soluble receptor for advanced glycation end-products (sRAGE), PCOS parameters, and ART outcome.

RESULT(S)

In human granulosa cells, VD alters AMH signaling, FSH sensitivity, and progesterone production and release, indicating a possible physiologic role for VD in ovarian follicular development and luteinization. In the serum, 25-hydroxyvitamin D (25OH-D) is positively correlated with AMH, and appropriate VD supplementation in VD-depleted women can suppress the seasonal changes that occur in serum AMH. In VD-deficient women with PCOS, VD supplementation lowers the abnormally elevated serum AMH levels, possibly indicating a mechanism by which VD improves folliculogenesis. The antiinflammatory sRAGE serum levels significantly increase in women with PCOS after VD replacement. Although follicular fluid 25OH-D correlates with IVF outcomes, there is a lack of data pertaining to the impact of VD supplementation on pregnancy rates following IVF.

CONCLUSION(S)

This review underscores the need for understanding the mechanistic actions of VD in ovarian physiology and the critical need for randomized trials to elucidate the impact of VD supplementation on controlled ovarian hyperstimulation/IVF outcome and ovulatory dysfunction associated with PCOS.

Vitamin D alters genes involved in follicular development and steroidogenesis in human cumulus granulosa cells

CONTEXT

Vitamin D deficiency is common among reproductive-aged women and has a role in female reproduction.

OBJECTIVE

This study evaluated the role of 1,25-dihydroxyvitamin D3 (vit D3) in ovarian follicular development and steroidogenesis by using a human granulosa cell (GC) model.

DESIGN, SETTING, AND PARTICIPANTS

Fifty-four women who underwent in vitro fertilization were enrolled.

INTERVENTION

Follicular fluid (FF) and mural and cumulus GCs were collected from small and large follicles. In separate experiments, primary cumulus GCs were cultured with or without vit D3 followed by RT-PCR for mRNA expression levels. The effect of recombinant anti-Mullerian hormone (AMH) on nuclear localization of phospho-Smad 1/5/8 was evaluated in the presence or absence of vit D3 by using immunofluorescence. 25-Hydroxyvitamin D levels in FF as well as cell culture media AMH, progesterone, and estradiol (E2) concentrations were determined by ELISA and RIA.

MAIN OUTCOME MEASURES

The following were measured: 1) mRNA expression levels; 2) 3β-hydroxysteroid dehydrogenase (3β-HSD) enzyme activity; 3) FSH-induced aromatase mRNA and E2 production; and 4) nuclear localization of phospho-Smad 1/5/8.

RESULTS

In a multivariate analysis, 25 OH-D levels in FF negatively correlated with AMH and AMH receptor (AMHR)-II mRNA levels in cumulus GCs of small follicles. Compared with women with replete 25-hydroxyvitamin D levels in FF, those with insufficient/deficient levels had a 2-fold increase in AMHR-II mRNA levels in cumulus GCs of small follicles (P = .02). Treatment with vit D3 caused a decrease in AMHR-II and FSH receptor mRNA but an increase in 3-βHSD mRNA levels compared with control (P < .05). Vit D3 enhanced 3-βHSD enzyme activity as assessed by increasing progesterone release; however, vit D3 did not affect FSH-induced aromatase mRNA and E2 production, but it decreased the phosphorylation of Smad 1/5/8 and its nuclear localization.

CONCLUSION

These data suggest that vit D3 alters AMH signaling and steroidogenesis in human cumulus GCs, possibly reflecting a state of GC luteinization potentiation.

IGF binding proteins in cancer: mechanistic and clinical insights

The six members of the family of insulin-like growth factor (IGF) binding proteins (IGFBPs) were originally characterized as passive reservoirs of circulating IGFs, but they are now understood to have many actions beyond their endocrine role in IGF transport. IGFBPs also function in the pericellular and intracellular compartments to regulate cell growth and survival - they interact with many proteins, in addition to their canonical ligands IGF-I and IGF-II. Intranuclear roles of IGFBPs in transcriptional regulation, induction of apoptosis and DNA damage repair point to their intimate involvement in tumour development, progression and resistance to treatment. Tissue or circulating IGFBPs might also be useful as prognostic biomarkers.

Cell-autonomous regulation of brown fat identity gene UCP1 by unliganded vitamin D receptor

White adipose tissue stores energy in the form of lipids, and brown adipose tissue expends energy via uncoupled fatty acid oxidation, which leads to the generation of heat. Obesity reflects an imbalance between energy storage and energy expenditure and is strongly associated with metabolic and cardiovascular disease. Therefore, there are important medical and biological implications for elucidating the mechanisms that promote energy expenditure in humans. Animal models with altered vitamin D receptor (VDR) expression have changes in energy expenditure. However, the specific mechanism for this effect has not been elucidated and the relevance for humans is unclear. Here we show, using human patient samples from individuals with hereditary vitamin D resistant rickets, that the VDR directly inhibits the expression of uncoupling protein-1 (UCP1), the critical protein for uncoupling fatty acid oxidation in brown fat and burning energy. The inhibition is enforced by VDR occupancy of a negative response element in the promoter proximal region of the UCP1 gene. Deletion of VDR increases UCP1 expression and results in a "browning" of adipocytes. Importantly, we found that this process occurs cell autonomously and is independent of the physiologic VDR hormone ligand, 1,25-dihydroxyvitamin D. These results identify a mechanism for modulating energy balance in humans.

Low-dose 1,25-dihydroxyvitamin D(3) combined with arsenic trioxide synergistically inhibits proliferation of acute myeloid leukemia cells by promoting apoptosis

Arsenic trioxide (As(2)O(3)) has shown substantial efficacy in the treatment of patients with acute promyelocytic leukemia, a specific subtype of acute myeloid leukemia (AML). However, since not all patients can achieve remission after treatment, it is necessary to develop a novel method to overcome this problem. We investigated the anti-leukemic effect of low-dose 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) in combination with As(2)O(3) on the human AML cell lines HL-60 and K562. The cell viability was in reverse proportion to As(2)O(3) or 1,25(OH)(2)D(3) concentration. In both HL-60 and K562 cells, after the combination treatment with As(2)O(3) and 1,25(OH)(2)D(3) at a 10:1 ratio, the combination index (CI) values were <1 in all treatment groups. In the RT-PCR and western blot analysis, the combination treatment decreased Bcl-2 expression and increased Bax and caspase-3 expression more prominently than the single treatment. In the flow cytometric analysis performed in HL-60 cells, the proportion of late apoptotic cells was 4.9% in the control, 30.0% in cells treated with 1.0 µM As(2)O(3), 8.1% in cells treated with 100 nM 1,25(OH)(2)D(3), and 64.3% in cells treated with 1.0 µM As(2)O(3) plus 100 nM 1,25(OH)(2)D(3). In conclusion, low-dose 1,25(OH)(2)D(3) combined with As(2)O(3) synergistically inhibited proliferation of HL-60 and K562 cells. In addition, this combination activated the apoptosis pathway more prominently than the single-drug treatment.

Antineoplastic effects of 1,25(OH)2D3 and its analogs in breast, prostate and colorectal cancer

The active form of vitamin D3, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), is mostly known for its importance in the maintenance of calcium and phosphate homeostasis. However, next to its classical effects on bone, kidney and intestine, 1,25(OH)2D3 also exerts antineoplastic effects on various types of cancer. The use of 1,25(OH)2D3 itself as treatment against neoplasia is hampered by its calcemic side effects. Therefore, 1,25(OH)2D3-derived analogs were developed that are characterized by lower calcemic side effects and stronger antineoplastic effects. This review mainly focuses on the role of 1,25(OH)2D3 in breast, prostate and colorectal cancer (CRC) and the underlying signaling pathways. 1,25(OH)2D3 and its analogs inhibit proliferation, angiogenesis, migration/invasion and induce differentiation and apoptosis in malignant cell lines. Moreover, prostaglandin synthesis and Wnt/b-catenin signaling are also influenced by 1,25(OH)2D3 and its analogs. Human studies indicate an inverse association between serum 25(OH)D3 values and the incidence of certain cancer types. Given the literature, it appears that the epidemiological link between vitamin D3 and cancer is the strongest for CRC, however more intervention studies and randomized placebo-controlled trials are needed to unravel the beneficial dose of 1,25(OH)2D3 and its analogs to induce antineoplastic effects.

Follicle selection in the avian ovary

Follicle development in the highly efficient laying hen is characterized by a well-organized follicular hierarchy. This is not the case in other chickens such as the broiler breeder hen that has excessive follicle development and lower reproductive efficiency. Although management practices can optimize egg production in less productive breeds of chickens, the factors that contribute to this difference are not known. Interactions between the oocyte and surrounding somatic cells are believed to be involved in promoting follicle selection. Anti-Müllerian hormone (AMH) has been shown to have a role in regulating rate of follicle development in mammals. In hens, the expression of AMH is restricted to the growing population of follicles and, similar to mammals, is markedly decreased at around the time of follicle selection. The oocyte factors, growth and differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), have been identified in the hen, and their expression pattern has been characterized. Anti-Müllerian hormone expression in hens is decreased by a protein factor from the oocyte (not GDF9) and is also decreased by vitamin D. Associated with the decrease in AMH expression by vitamin D, follicle-stimulating hormone receptor mRNA is increased. These data suggest that information about AMH regulation may enhance our understanding of follicle selection, particularly in birds with aberrant follicle development.

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.

Relative Expression of Vitamin D Hydroxylases, CYP27B1 and CYP24A1, and of Cyclooxygenase-2 and Heterogeneity of Human Colorectal Cancer in Relation to Age, Gender, Tumor Location, and Malignancy: Results from Factor and Cluster Analysis

Previous studies on the significance of vitamin D insufficiency and chronic inflammation in colorectal cancer development clearly indicated that maintenance of cellular homeostasis in the large intestinal epithelium requires balanced interaction of 1,25-(OH)₂D₃ and prostaglandin cellular signaling networks. The present study addresses the question how colorectal cancer pathogenesis depends on alterations of activities of vitamin D hydroxylases, i.e., CYP27B1-encoded 25-hydroxyvitamin D-1α-hydroxylase and CYP24A1-encoded 25-hydroxyvitamin D-24-hydroxylase, and inflammation-induced cyclooxygenase-2 (COX-2). Data from 105 cancer patients on CYP27B1, VDR, CYP24A1, and COX-2 mRNA expression in relation to tumor grade, anatomical location, gender and age were fit into a multivariate model of exploratory factor analysis. Nearly identical results were obtained by the principal factor and the maximum likelihood method, and these were confirmed by hierarchical cluster analysis: Within the eight mutually dependent variables studied four independent constellations were found that identify different features of colorectal cancer pathogenesis: (i) Escape of COX-2 activity from restraints by the CYP27B1/VDR system can initiate cancer growth anywhere in the colorectum regardless of age and gender; (ii) variations in COX-2 expression are mainly responsible for differences in cancer incidence in relation to tumor location; (iii) advancing age has a strong gender-specific influence on cancer incidence; (iv) progression from well differentiated to undifferentiated cancer is solely associated with a rise in CYP24A1 expression.

15-Hydroxyprostaglandin dehydrogenase as a novel molecular target for cancer chemoprevention and therapy

Cyclooxygenase-2 (COX-2), a rate-limiting enzyme in arachidonic acid cascade, plays a key role in the biosynthesis of prostaglandin E(2) (PGE(2)) upon inflammatory insults. Overproduction of PGE(2) stimulates proliferation of various cancer cells, confers resistance to apoptosis of cancerous or transformed cells, and accelerates metastasis and angiogenesis. Excess PGE(2) undergoes metabolic inactivation which is catalyzed by NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH). In this context, 15-PGDH has been speculated as a physiological antagonist of COX-2 and a tumor suppressor. Thus, overexpression of 15-PGDH has been known to protect against experimentally induced carcinogenesis and renders the cancerous or transformed cells susceptible to apoptosis by counteracting oncogenic action of PGE(2). In contrast, silence of 15-PGDH is observed in some cancer cells, which is associated with epigenetic modification, such as DNA methylation and histone deacetylation, in the promoter region of 15-PGDH. A variety of compounds capable of inducing the expression of 15-PGDH have been reported, which include the histone deacetylase inhibitors, nonsteroidal anti-inflammatory drugs, and peroxisome proliferator-activated receptor-gamma agonists. Therefore, 15-PGDH may be considered as a novel molecular target for cancer chemoprevention and therapy. This review highlights the role of 15-PGDH in carcinogenesis and its regulation.

Vitamin d, sunlight and prostate cancer risk

Prostate cancer is the second common cancer in men worldwide. The prevention of prostate cancer remains a challenge to researchers and clinicians. Here, we review the relationship of vitamin D and sunlight to prostate cancer risk. Ultraviolet radiation of the sunlight is the main stimulator for vitamin D production in humans. Vitamin D's antiprostate cancer activities may be involved in the actions through the pathways mediated by vitamin D metabolites, vitamin D metabolizing enzymes, vitamin D receptor (VDR), and VDR-regulated genes. Although laboratory studies including the use of animal models have shown that vitamin D has antiprostate cancer properties, whether it can effectively prevent the development and/or progression of prostate cancer in humans remains to be inconclusive and an intensively studied subject. This review will provide up-to-date information regarding the recent outcomes of laboratory and epidemiology studies on the effects of vitamin D on prostate cancer prevention.

Role of vitamin d in the prevention of pancreatic cancer

Pancreatic cancer is a malignancy of poor prognosis which is mostly diagnosed at advanced stages. Current treatment modalities are very limited creating great interest for novel preventive and therapeutic options. Vitamin D seems to have a protective effect against pancreatic cancer by participating in numerous proapoptotic, antiangiogenic, anti-inflammatory, prodifferentiating, and immunomodulating mechanisms. 25-hydroxyvitamin D [25(OH)D] serum concentrations are currently the best indicator of vitamin D status. There are three main sources of vitamin D: sun exposure, diet,and dietary supplements. Sun exposure has been associated with lower incidence of pancreatic cancer in ecological studies. Increased vitamin D levels seem to protect against pancreatic cancer, but caution is needed as excessive dietary intake may have opposite results. Future studies will verify the role of vitamin D in the prevention and therapy of pancreatic cancer and will lead to guidelines on adequate sun exposure and vitamin D dietary intake.

Vitamin D and breast cancer: inhibition of estrogen synthesis and signaling

Calcitriol (1,25-dihydroxyvitamin D3), the hormonally active metabolite of vitamin D, inhibits the growth and induces the differentiation of many malignant cells including breast cancer (BCa) cells. Calcitriol exerts its anti-proliferative activity in BCa cells by inducing cell cycle arrest and stimulating apoptosis. Calcitriol also inhibits invasion, metastasis and tumor angiogenesis in experimental models of BCa. Our recent studies show additional newly discovered pathways of calcitriol action to inhibit the growth of BCa cells. Calcitriol suppresses COX-2 expression and increases that of 15-PGDH thereby reducing the levels and biological activity of prostaglandins (PGs). Calcitriol decreases the expression of aromatase, the enzyme that catalyzes estrogen synthesis selectively in BCa cells and the breast adipose tissue surrounding BCa, by a direct repression of aromatase transcription via promoter II as well as an indirect effect due to the reduction in the levels and biological activity of PGE2, which is a major stimulator of aromatase transcription through promoter II in BCa. Calcitriol down-regulates the expression of estrogen receptor alpha and thereby attenuates estrogen signaling in BCa cells including the proliferative stimulus provided by estrogens. We hypothesize that the inhibition of estrogen synthesis and signaling by calcitriol and its anti-inflammatory actions will play an important role in the use of calcitriol for the prevention and/or treatment of BCa.

Vitamins and prostate cancer risk

Prostate cancer (PC) is the second most common cancer in men worldwide. Its prevention and treatment remain a challenge to clinicians. Here we review the relationship of vitamins to PC risk. Many vitamins and related chemicals, including vitamin A, retinoids, several B vitamins, vitamin C, vitamin D and vitamin E have shown their anti-cancer activities as anti-oxidants, activators of transcription factors or factors influencing epigenetic events. Although laboratory tests including the use of animal models showed these vitamins may have anti-PC properties, whether they can effectively prevent the development and/or progression of PC in humans remains to be intensively studied subjects. This review will provide up-to-date information regarding the recent outcomes of laboratory, epidemiology and/or clinical trials on the effects of vitamins on PC prevention and/or treatment.

Vitamin D: considerations in the continued development as an agent for cancer prevention and therapy

Considerable preclinical and epidemiologic data suggest that vitamin D may play a role in the pathogenesis, progression, and therapy for cancer. Numerous epidemiologic studies support the hypothesis that individuals with lower serum vitamin D levels have a higher risk of a number of cancers. Measures of vitamin D level in such studies include both surrogate estimates of vitamin D level (residence in more northern latitudes, history of activity, and sun exposure) as well as measured serum 25(OH) cholecalciferol levels. Perhaps, the most robust of these epidemiologic studies is that of Giovannucci et al, who developed and validated an estimate of serum 25(OH) cholecalciferol level and reported that among >40,000 individuals in the Health Professionals Study, an increase in 25(OH) cholecalciferol level of 62.5 ng/mL was associated with a reduction in the risk of head/neck, esophagus, pancreas cancers, and acute leukemia by >50%. Unfortunately, very limited data are available to indicate whether or not giving vitamin D supplements reduces the risk of cancer. Many preclinical studies indicate that exposing cancer cells, as well as vascular endothelial cells derived from tumors, to high concentrations of active metabolites of vitamin D halts progression through cell cycle, induces apoptosis and will slow or stop the growth of tumors in vivo. There are no data that one type of cancer is more or less susceptible to the effects of vitamin D. Vitamin D also potentiates the antitumor activity of a number of types of cytotoxic anticancer agents in in vivo preclinical models. Vitamin D analogues initiate signaling through a number of important pathways, but the pathway(s) essential to the antitumor activities of vitamin D are unclear. Clinical studies of vitamin D as an antitumor agent have been hampered by the lack of a suitable pharmaceutical preparation for clinical study. All commercially available formulations are inadequate because of the necessity to administer large numbers of caplets and the poor "bioavailability" of calcitriol (the most carefully studied analogue) at these high doses. Preclinical data suggest that high exposures to calcitriol are necessary for the antitumor effects. Clinical data do indicate that high doses of calcitriol (>100 mcg weekly, intravenously, and 0.15 microg /kg weekly, orally) can be given safely. The maximum tolerated dose of calcitriol is unclear. While a 250-patient trial in men with castration-resistant prostate cancer comparing docetaxel (36 mg/sqm weekly) +/- calcitriol 0.15 microg/kg indicated that calcitriol was very safe may have reduced to death rate, an adequately powered (1000 patients) randomized study of weekly docetaxel + calcitriol versus q3 week docetaxel was negative. The limitations of this trial were the unequal chemotherapy arms compared in this study and the failure to use an optimal biologic dose or maximum-tolerated dose of calcitriol. In view of the substantial preclinical and epidemiologic data supporting the potential role of vitamin D in cancer, careful studies to evaluate the impact of vitamin D replacement on the frequency of cancer and the impact of an appropriate dose and schedule of calcitriol or other active vitamin D analogue on the treatment of established cancer are indicated.

The relation of serum parathyroid hormone and serum calcium to serum levels of prostate-specific antigen: a population-based study

Experimental and clinical data implicate calcium and parathyroid hormone (PTH) in the development of prostate cancer. However, epidemiologic data on the role of these variables in prostate health are sparse. We examined the relationship between serum levels of calcium, PTH, and prostate-specific antigen (PSA), an established marker of prostate growth, in a large, population-based study using multivariate linear regression. We studied 1,273 men in National Health and Nutrition Survey 2005 to 2006 who were >or=40 years of age and who were without clinical prostate cancer. Adjusted for age, race, body mass index, and serum levels of 25-hydroxyvitamin D, serum levels of PTH were significantly positively correlated with serum PSA (P = 0.01). Serum levels of PTH and calcium each were correlated significantly with free PSA (P = 0.05 and 0.008, respectively). The percentage of men who had elevated serum levels of PTH (PTH, >or=66 pg/mL) was significantly greater among African American men (19.2 versus 9.6%, P = 0.04). Compared with men whose PTH was at the lower end of the reference range, the predicted PSA for men with a PTH of 66 pg/mL was increased 43%. These findings support the hypothesis that serum calcium and serum PTH stimulate prostate growth in men without clinical prostate cancer and have implications for the use of PSA as a screening tool for prostate cancer.

Unraveling insulin-like growth factor binding protein-3 actions in human disease

The IGF system plays critical roles in somatic growth in an endocrine fashion (somatomedin hypothesis) as well as proliferation and differentiation of normal and malignant cells in a paracrine/autocrine fashion. IGFBP-3 is known to modulate the actions of IGFs in circulation as well as the immediate extracellular environment. Interestingly, apart from the ability to inhibit or enhance IGF actions, IGFBP-3 also exhibits very clear, distinct biological effects independent of the IGF/IGF-I receptor axis. Over the past decade it has become widely appreciated that IGF/IGF-IR-independent actions of IGFBP-3 (antiproliferative and proapoptotic effects) contribute to improving the pathophysiology of a variety of human diseases, such as cancer, diabetes, and malnutrition. Recent studies have implicated interaction of IGFBP-3 with a variety of proteins or signaling cascades critical to cell cycle control and apoptosis; however, the actual mechanism of IGFBP-3 action is still unclear. This review reinforces the concept in support of the IGF/IGF-IR axis-independent actions of IGFBP-3 and delineates potential underlying mechanisms involved and subsequent biological significance, focusing in particular on functional binding partners and the clinical significance of IGFBP-3 in the assessment of cancer risk.

The promiscuous receptor

OBJECTIVE

To determine the effectiveness of vitamin D therapy in patients with asymptomatic, prostate-specific antigen (PSA)-progression of prostate cancer.

PATIENTS AND METHODS

Twenty-six patients with locally advanced or metastatic prostate cancer were treated with vitamin D. Vitamin D therapy was discontinued on disease progression as assessed by symptoms or serum PSA increase. The response to therapy was judged from changes in PSA level from the pretreatment baseline to 3 months after starting vitamin D therapy.

RESULTS

Of the 26 patients, five (20%) responded to vitamin D; the mean (range) reduction in PSA level was 45.3 (15.9-95.1)%, and mean duration of response was 4-5 months. Patients in whom the PSA level was stabilized, but not reduced, after vitamin D treatment had a duration of response of up to 36 months. Treatment was well tolerated and was not associated with elevation of serum calcium levels. There was no significant correlation between response to therapy and stage of disease, Gleason grade, previous treatments or PSA level at diagnosis or initiation of vitamin D therapy.

CONCLUSION

Vitamin D therapy is an effective and well tolerated treatment for patients with asymptomatic progressive prostate cancer, and is a useful addition to the therapeutic options.

Interaction of the vitamin D receptor with a vitamin D response element in the Mullerian-inhibiting substance (MIS) promoter: regulation of MIS expression by calcitriol in prostate cancer cells

Calcitriol (1,25-dihydroxyvitamin D(3)) inhibits the growth of a variety of cancer cells including human prostate cancer. Müllerian-inhibiting substance (MIS) also exhibits antiproliferative and proapoptotic actions on multiple cancer cells including human prostate cancer. In this study, we investigated whether calcitriol regulated MIS expression in prostate cancer, an action that might contribute to its antiproliferative activity. We identified a 15-bp sequence, GGGTGAgcaGGGACA, in the MIS promoter that was highly similar to direct repeat 3-type vitamin D response elements (VDREs). The human MIS promoter containing the putative VDRE was cloned into a luciferase reporter vector. In HeLa cells transfected with the vitamin D receptor (VDR), MIS promoter activity was stimulated by calcitriol. Coexpression of steroidogenic factor 1, a key regulator of MIS, increased basal MIS promoter activity that was further stimulated by calcitriol. Mutation or deletion of the VDRE reduced calcitriol-induced transactivation. In addition, the MIS VDRE conferred calcitriol responsiveness to a heterologous promoter. In gel shift assays, VDR and retinoid X receptor bound to the MIS VDRE and the binding was increased by calcitriol. Chromatin immunoprecipitation assays showed that VDR and retinoid X receptor were present on the MIS promoter in prostate cancer cells. In conclusion, we demonstrated that MIS is a target of calcitriol action. MIS is up-regulated by calcitriol via a functional VDRE that binds the VDR. Up-regulation of MIS by calcitriol may be an important component of the antiproliferative actions of calcitriol in some cancers.

The vitamin D receptor agonist elocalcitol inhibits IL-8-dependent benign prostatic hyperplasia stromal cell proliferation and inflammatory response by targeting the RhoA/Rho kinase and NF-kappaB pathways

BACKGROUND

Benign prostatic hyperplasia (BPH) is characterized by an important inflammatory component. Stimulation of human prostate stromal cells from BPH tissues with proinflammatory cytokines leads to secretion of IL-8, a chemokine involved in BPH pathogenesis. The vitamin D receptor (VDR) agonist elocalcitol can arrest prostate growth in BPH patients, but its mechanism of action in this pathology is still incompletely understood.

METHODS

IL-8 levels were measured by real-time RT-PCR and ELISA. NF-kappaB translocation and COX-2 expression were evaluated by confocal microscopy. RhoA and Rho-kinase (ROCK) gene expression and functional activity were studied by real-time RT-PCR, immuno-kinase assays, Western blot analysis, confocal microscopy, and cell invasion.

RESULTS

Stimulation of BPH cells with IL-8 activates the calcium-sensitizing RhoA/ROCK pathway, as demonstrated by the increased membrane translocation of RhoA and by phosphorylation of the ROCK substrate myosin phosphatase target subunit 1 (MYPT-1). In agreement with these data, C3 exoenzyme, a selective RhoA inhibitor, inhibits IL-8-induced invasion of BPH cells. The VDR agonist elocalcitol significantly inhibits IL-8 production by BPH cells stimulated with inflammatory cytokines, and IL-8-induced proliferation of BPH cells. In addition, elocalcitol inhibits IL-8-induced membrane translocation of RhoA and MYPT-1 phosphorylation in BPH cells, and inhibits dose-dependently their IL-8-dependent invasion. The inhibition induced by elocalcitol of IL-8 production by BPH cells is accompanied by decreased COX-2 expression and PGE(2) production and by arrest of NF-kappaB p65 nuclear translocation, associated with inhibition of the RhoA/ROCK pathway.

CONCLUSIONS

These data provide a mechanistic explanation for the anti-proliferative and anti-inflammatory properties of elocalcitol in BPH cells.

The association of bone mineral density with prostate cancer risk in the Osteoporotic Fractures in Men (MrOS) Study

We investigated the association of bone mineral density (BMD) measures with prostate cancer (PCa) risk in older men enrolled in the Osteoporotic Fractures in Men Study. We hypothesized that men with higher BMD, a marker of exposure to endogenous sex hormones, would have an increased incidence of PCa. The cohort included 4,597 men (89% White, 65 years or older) with no prior history of PCa. Baseline total body, total hip, and spine BMD were assessed using dual energy X-ray absorptiometry. Prostate cancer was confirmed by review of medical records. Cox regression was used to assess the association of BMD quartiles with incident PCa, adjusting for age, body mass index, and other covariates. During an average follow-up of 5.2 years, 5.6% (n = 255) of men developed PCa. Total body BMD was inversely associated with incident PCa, with a significant trend for decreasing PCa risk with increasing BMD quartiles (P(trend) = 0.007). Men in the highest total body BMD quartile had a 41% reduced risk for PCa (hazard ratio, 0.59; 95% confidence interval, 0.40-0.86), compared with men in the lowest quartile. Total hip and spine BMD did not exhibit significant relationships with PCa. Associations of BMD measures differed for low-grade (Gleason sum, 2-6) versus high-grade tumors (Gleason sum, >or=7). Significant inverse relationships with high-grade disease were noted at the total body and total hip sites. However, no associations were observed with low-grade disease. Our results provide support for an inverse association between BMD and PCa risk. Possible pathophyisological mechanisms linking BMD and PCa should be elucidated.

Inactivation of the human vitamin D receptor by caspase-3

Calcitriol actions are mediated by the vitamin D receptor (VDR), a nuclear transcription factor of the steroid-retinoid-thyroid nuclear receptor gene superfamily. Calcitriol inhibits the growth of many cells including cancer cells by inducing cell cycle arrest. In some cancer cell lines, calcitriol also induces apoptosis. In the LNCaP prostate cancer cell line, induction of apoptosis and caspase-3/7 activities by staurosporine (STS) abolished [(3)H]1,25-dihydroxy vitamin D(3) binding and VDR protein, suggesting that the VDR may be targeted for inactivation by caspases during apoptosis. A potential caspase-3 site (D(195)MMD(198)S) was identified in the human VDR ligand-binding domain. Mutations D195A, D198A, and S199A were generated in the putative capase-3 cleavage site. In transfected COS-7 cells, STS treatment resulted in the cleavage of the wild-type (WT) VDR and S199A mutant VDR but not the D195A or D198A mutants. In in vitro assays, the WT VDR and S199A mutant VDR were cleaved by caspase-3, although the D195A and D198A mutants were resistant to caspase-3. In vitro, the WT VDR was also cleaved by caspase-6 and caspase-7 and in extracts of STS-treated LNCaP cells. In STS-treated LNCaP cells and human skin fibroblasts, the proteasome inhibitor MG-132 protected the VDR caspase cleavage fragment from further degradation by the 26S proteasome. The rat VDR that does not contain the caspase-3 cleavage site was not cleaved in STS-treated COS-7 cells. In conclusion, our results demonstrate that the human VDR is a target of caspase-3 and suggest that activation of caspase-3 may limit VDR activity.