The role of vitamin D in cancer prevention and treatment

Estrogen receptor-mediated health benefits of phytochemicals: a review

Estrogen receptors (ERs) are transcription factors with two subtypes: estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), which are essential for the maintenance of human health and play a regulatory role in common diseases such as breast cancer, osteoporosis, neurodegenerative disorders, liver injuries and lung cancers. A number of phytochemicals extracted from various fruits and vegetables have been demonstrated to exhibit estrogenic effects and are termed phytoestrogens. As modulators of ERs, phytoestrogens can be involved in the prevention and treatment of multiple diseases as complementary or alternative therapeutic agents and have a variety of health benefits for humans. This article reviews the health benefits of phytoestrogens in clinical and epidemiologic studies for several diseases and also provides a detailed description of the molecular mechanisms of their action. A brief comparison of the advantages and disadvantages of natural phytochemicals compared to synthetic drugs is also presented. The role of phytoestrogens in the treatment of diseases and human health requires further research to fully realize their therapeutic potential.

Efficacy of vitamin D3 supplementation on cancer mortality: Systematic review and individual patient data meta-analysis of randomised controlled trials

To evaluate the effect of vitamin D3 supplementation on cancer mortality in the general population and on prognosis in cancer patients, a systematic review and meta-analysis of randomised, placebo-controlled trials (RCTs) and individual patient data (IPD) was conducted. Overall, 14 RCTs with a total of 104,727 participants (2015 cancer deaths) were identified and 7 RCTs, including 90 % of all study participants (n = 94,068), could be included in the IPD meta-analyses. The main meta-analysis of the 14 RCTs yielded a statistically non-significant reduction in cancer mortality by 6 % (risk ratio (RR) [95%-confidence interval (95%CI)]: 0.94 [0.86-1.02]). Subgroup analyses revealed a 12 % lower cancer mortality in the vitamin D3 group compared with the placebo group in 10 trials with a daily dosing regimen (RR [95%CI]: 0.88 [0.78-0.98]), whereas no mortality reduction was seen in 4 trials using a bolus regimen (RR [95%CI]: 1.07 [0.91-1.24]; p-value for interaction: 0.042). The IPD meta-analysis (RR [95%CI]: 0.93 [0.84; 1.02]) confirmed the finding of all trials. The IPD were used to test effect modification by age, sex, body mass index, ethnicity, baseline serum 25-hydroxyvitamin D concentration, adherence and cancer-related factors but no statistically significant findings were obtained in meta-analyses of all trials. When restricted to trials with daily dosing in a post-hoc analysis, adults aged ≥ 70 years (RR [95%CI]: 0.83 [0.77; 0.98]) and subjects with vitamin D3 therapy initiation before cancer diagnosis (RR [95%CI]: 0.87 [0.69; 0.99]) appeared to benefit most from daily vitamin D3 supplementation. Measurements of baseline 25-hydroxyvitamin D levels and inclusion of other than non-Hispanic White adults were too sparse in the trials to draw conclusions. Results for all-cause and cancer-specific survival of participants with cancer were comparable to those obtained in the general population for cancer mortality. In conclusion, vitamin D3 did not reduce cancer mortality in the main meta-analysis of all RCTs because the observed risk reduction by 6 % was not statistically significant. However, a subgroup analysis revealed that vitamin D3 administered daily, in contrast to bolus supplementation, reduced cancer mortality by 12 %.

25-Hydroxycholecalciferol Inhibits Cell Growth and Induces Apoptosis in SiHa Cervical Cells via Autocrine Vitamin D Metabolism

Preclinical studies show that the anticancer actions of vitamin D metabolites are mediated by apoptosis, inhibition of cell proliferation and induction of cell cycle arrest. Cervical cancer cells express an autocrine vitamin D metabolising system (VDMS) comprised of a vitamin D receptor, vitamin D catabolic enzyme (CYP24A1), and the activating enzyme of 25-hydroxycholecalciferol (25(OH)D3), CYP27B1. We assessed the anticancer effects of 25(OH)D3 at clinically relevant concentrations on a cervical squamous cell cancer cell line, SiHa. We evaluated cell health parameters (cell count, viability, and cell cycle), cell death modes (apoptosis, autophagic-dependent death, and necrosis by flow cytometry and transmission electron microscopy), and autocrine VDMS gene and protein expression by qPCR and Western blot, respectively. Our study demonstrates that physiological and supraphysiological doses of 25(OH)D3 inhibit cell growth and viability and induce biochemical and morphological apoptosis in SiHa cells. These growth effects are mediated by alteration in the VDMS gene and protein expression, with prominent negative feedback at supraphysiological treatment dose. These data identify promising therapeutic potential of 25(OH)D3 in cervical cancer, which warrants further clinical translational investigations.

Dry granulation of vitamin D3 and iron in corn starch matrix: Powder flow and structural properties

In this work, a twin-screw dry granulation (TSDG) was adopted to produce vitamin D3 (VD3) and iron blended dry granules using corn starch as an excipient. Response surface methodology was applied to determine the effect of the formulation compositions (VD3 and iron) on granule properties [tapped bulk density, oil holding capacity, and volumetric mean particle size (D_v50)]. Results indicated that the model fitted well, and responses, in particular flow properties, were significantly affected by the composition. The D_v50 was only influenced by the addition of VD3. The flow properties were characterized by the Carr index and Hausner ratio, which indicated very poor flow of the granules. Scanning electron microscopy with energy dispersive spectroscopy confirm the presence and distribution of Fe⁺⁺ and VD3 in the granules. Overall, TSDG was proven to be a simple alternative method for the preparation of dry granules of VD3 and iron in a blend.

Therapeutic effects of vitamin D and cancer: An overview

Since vitamin D's discovery, strenuous efforts to investigate its physiological exploit and deficiency on human health were done. Our body synthesizes fat‐soluble vitamin D when get exposed to sunlight. In recent years, experimental data indicate that sunlight exposure and an adequate level of circulating vitamin D can reduce the incidence of cancer. Several in vitro and in vivo studies also suggest vitamin D as a potentially valuable supplement for cancer treatment and prevention. Nevertheless, there need to be adequate clinical studies performed to substantiate the suppressive ability of vitamin D concerning cancer incidence. Thus, understanding the cellular mechanisms of vitamin D can be advantageous for preventing several chronic diseases. Consequently, this review concentrates on different studies that have been conducted to characterize the outcome of vitamin D in reducing cancer incidence and its medication by cellular progression mechanism.

Exploring the expression profile of vitamin D receptor and its related long non-coding RNAs in patients with acute lymphoblastic leukemia

OBJECTIVE

Acute lymphoblastic leukemia (ALL) is the most common type of childhood cancer. Previous studies have indicated the involvement of vitamin D receptor (VDR) and related long noncoding RNAs (lncRNAs) signaling in the pathophysiology of several cancers. However, their contribution to ALL remains to be elucidated.

METHODS

In this case-control study, 30 patients with newly diagnosed ALL and 30 age- and sex-matched healthy children were selected. Then, the level of 25(OH) vitamin D and the expression of VDR and four VDR-related lncRNAs were assessed.

RESULTS

No significant difference in serum 25(OH) vitamin D was observed between patients with ALL (20.42±6.5 ng/mL) and healthy subjects (25.45±11 ng/mL). In addition, the expression of MALAT-1, HOTAIR, and P-21 was not statistically significant between the two groups. However, a significant reduction in VDR and H19 expression was observed in patients with ALL (p<0.05).

CONCLUSIONS

25(OH) vitamin D insufficiency was evident in both groups. VDR and H19 signaling might be contributed to the pathogenesis of ALL, which needs further investigations.

Influence of Storage Conditions on the Stability of Vitamin D3 and Kinetic Study of the Vitamin Degradation in Fortified Canola Oil during the Storage

Nowadays, fortified vegetable oils with vitamin D3 are widely available in different countries. In this study, the influence of storage conditions including light, air, storage temperature, and time on vitamin D3 retention in fortified canola oil was evaluated. Moreover, a kinetic study on vitamin D3 degradation in the oil was done. To this aim, fortified canola oil was prepared at two initial concentrations of 6.87 mg·kg−1 and 13.8 mg·kg−1 and then filled in transparent and dark-brown polyethylene terephthalate bottles at two filling levels of 50% and 100%. Samples were kept in two temperatures of 4°C and room temperature (27°C). The retention of vitamin D3 in different samples showed that the vitamin content was affected by the packaging type, storage temperature, and initial concentration. Vitamin D3 in the samples with a lower concentration of the vitamin which was stored in the refrigerator showed the highest retention (91%) after 70 days of storage, and the samples with higher initial concentration packed in transparent containers which were stored at room temperature (RT) showed the greatest loss (55.6%). Results of the kinetic study also showed that vitamin D3 was affected by storage condition. The half-life of the vitamin D3 differed from 96 to 577 days depending on the storage condition.

Obesity, oxidative DNA damage and vitamin D as predictors of genomic instability in children and adolescents

BACKGROUND/OBJECTIVES

Epidemiological evidence indicates obesity in childhood and adolescence to be an independent risk factor for cancer and premature mortality in adulthood. Pathological implications from excess adiposity may begin early in life. Obesity is concurrent with a state of chronic inflammation, a well-known aetiological factor for DNA damage. In addition, obesity has been associated with micro-nutritional deficiencies. Vitamin D has attracted attention for its anti-inflammatory properties and role in genomic integrity and stability. The aim of this study was to determine a novel approach for predicting genomic instability via the combined assessment of adiposity, DNA damage, systemic inflammation, and vitamin D status.

SUBJECTS/METHODS

We carried out a cross-sectional study with 132 participants, aged 10-18, recruited from schools and paediatric obesity clinics in London. Anthropometric assessments included BMI Z-score, waist and hip circumference, and body fat percentage via bioelectrical impedance. Inflammation and vitamin D levels in saliva were assessed by enzyme-linked immunosorbent assay. Oxidative DNA damage was determined via quantification of 8-hydroxy-2'-deoxyguanosine in urine. Exfoliated cells from the oral cavity were scored for genomic instability via the buccal cytome assay.

RESULTS

As expected, comparisons between participants with obesity and normal range BMI showed significant differences in anthropometric measures (p < 0.001). Significant differences were also observed in some measures of genomic instability (p < 0.001). When examining relationships between variables for all participants, markers of adiposity positively correlated with acquired oxidative DNA damage (p < 0.01) and genomic instability (p < 0.001), and negatively correlated with vitamin D (p < 0.01). Multiple regression analyses identified obesity (p < 0.001), vitamin D (p < 0.001), and oxidative DNA damage (p < 0.05) as the three significant predictors of genomic instability.

CONCLUSIONS

Obesity, oxidative DNA damage, and vitamin D deficiency are significant predictors of genomic instability. Non-invasive biomonitoring and predictive modelling of genomic instability in young patients with obesity may contribute to the prioritisation and severity of clinical intervention measures.

Research Progress of TXNIP as a Tumor Suppressor Gene Participating in the Metabolic Reprogramming and Oxidative Stress of Cancer Cells in Various Cancers

Thioredoxin-interacting protein (TXNIP) is a thioredoxin-binding protein that can mediate oxidative stress, inhibit cell proliferation, and induce apoptosis by inhibiting the function of the thioredoxin system. TXNIP is important because of its wide range of functions in cardiovascular diseases, neurodegenerative diseases, cancer, diabetes, and other diseases. Increasing evidence has shown that TXNIP expression is low in tumors and that it may act as a tumor suppressor in various cancer types such as hepatocarcinoma, breast cancer, and lung cancer. TXNIP is known to inhibit the proliferation of breast cancer cells by affecting metabolic reprogramming and can affect the invasion and migration of breast cancer cells through the TXNIP-HIF1α-TWIST signaling axis. TXNIP can also prevent the occurrence of bladder cancer by inhibiting the activation of ERK, which inhibits apoptosis in bladder cancer cells. In this review, we find that TXNIP can be regulated by binding to transcription factors or other binding proteins and can also be downregulated by epigenetic changes or miRNA. In addition, we also summarize emerging insights on TXNIP expression and its functional role in different kinds of cancers, as well as clarify its participation in metabolic reprogramming and oxidative stress in cancer cells, wherein it acts as a putative tumor suppressor gene to inhibit the proliferation, invasion, and migration of different tumor cells as well as promote apoptosis in these cells. TXNIP may therefore be of basic and clinical significance for finding novel molecular targets that can facilitate the diagnosis and treatment of malignant tumors.

VD3 and LXR agonist (T0901317) combination demonstrated greater potency in inhibiting cholesterol accumulation and inducing apoptosis via ABCA1-CHOP-BCL-2 cascade in MCF-7 breast cancer cells

Obesity is associated with hypercholesterolemia and is a global epidemic. Epidemiological and animal studies revealed cholesterol is an essential regulator of estrogen receptor positive (ER+) breast cancer progression while inhibition of cholesterol accumulation was found to prevent breast tumor growth. Individually, vitamin D and LXR agonist T0901317 showed anticancer properties. The present study investigated the effects of vitamin D₃ (VD₃, calcitriol), LXR agonist (T0901317) and a combination of VD₃ + T0901317 on cholesterol metabolism and cancer progression in ER+ breast cancer (MCF-7) cells. VD₃ or T0901317 alone reduced cholesterol accumulation significantly in MCF-7 cells concomitant with an induction of ABCA1 protein and gene expression compared to the control treatment. Most importantly, VD₃ + T0901317 combination showed higher effects in reducing cholesterol levels and increasing ABCA1 protein and gene expression compared to individual treatments. Importantly, VD₃ + T0901317 combination showed higher effects in increasing apoptosis as measured by annexin apoptosis assay, cell viability and was associated with induction of CHOP protein and gene expression. Additionally, the VD₃ + T0901317 exerted higher effects in reducing antiapoptotic BCL-2 while increased pro-apoptotic BAX gene expression compared to the individual treatments. The present results suggest that VD₃ and T0901317 combination may have an important therapeutic application to prevent obesity and hyperlipidemia mediated ER+ breast cancer progression.

Vitamin D deficiency and metabolic syndrome in elderly Chinese individuals: evidence from CLHLS

Objectives

Both low vitamin D status and metabolic syndrome (MetS) are worldwide concerns, and low 25-hydroxyvitamin D [25(OH)D] levels are associated with MetS; however, related epidemiological evidence based on elderly Chinese individuals, especially those over 80 years of age, is limited. In the present study, we aimed to evaluate the association between serum 25(OH)D and MetS in elderly Chinese individuals.

Method

Serum 25(OH)D was measured in a cross-sectional sample of 2493 elderly people aged 65–112 years from eight areas of China in which the density of centenarians is exceptionally high. MetS was diagnosed according to blood pressure, lipid, and blood sugar levels; waist circumference; and body mass index (BMI). Adjusted multivariable logistic regression was used to analyze the associations between vitamin D and MetS based on different diagnostic criterias.

Results

A total of 890 (35.7%) of the recruited elderly individuals had insufficient levels of vitamin D, and 1029 participants (41.3%) were vitamin D deficient. High serum vitamin D concentrations were associated with a low prevalence of MetS according to the modified Adult Treatment Panel III (ATP III) criteria for adequate versus deficient vitamin D levels (OR: 0.63, 95% CI: 0.45, 0.88) and inadequate versus deficient vitamin D levels (OR: 0.70, 95% CI: 0.52, 0.92). Each 10 ng/ml increase in serum vitamin D was significantly associated with a decreased prevalence of MetS according to the modified ATP III criteria for people with normal waist circumference (WC) (OR: 0.55, 95% CI: 0.43,0.71). However, no significant statistical correlation was found among elderly people with a high WC. Additionally, in the analysis of the individual components, the ORs of adequate versus deficient vitamin D levels were 0.46 (95% CI: 0.30, 0.71) for elevated triglycerides and 0.64 (95% CI: 0.42, 0.97) for reduced high-density lipoprotein cholesterol (HDL-C) after adjustment for other components.

Conclusions

Vitamin D deficiency is very common among elderly Chinese individuals. Vitamin D deficiency may be a risk factor for MetS; however, the association was only statistically significant among elderly people with noncentral obesity. Further studies are needed to examine the causal direction of the association.

Vitamin D3 as adjuvant in the treatment of type 2 diabetes mellitus: modulation of genomic and biochemical instability

Type 2 diabetes mellitus has undergone a worldwide growth in incidence in the world and has now acquired epidemic status. There is a strong link between type 2 diabetes and vitamin D deficiency. Because vitamin D has beneficial effects on glucose homeostasis, the aim of this study was to evaluate the influence of vitamin D3 supplementation on the modulation of glycaemic control and other metabolic effects, as well as modulation of genomic instability in patients with type 2 diabetes. We evaluated 75 patients with type 2 diabetes, registered in the Integrated Clinics of the University of Southern Santa Catarina. Participants received 4000 IU of vitamin D3 (25(OH)D) supplementation daily for 8 weeks. Blood samples were collected at the beginning and at the end of the supplementation, and 4 weeks after the end of supplementation. The glycidic and lipid profiles [total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein and triglycerides], oxidative stress, DNA damage and 25(OH)D levels were evaluated. Vitamin D3 supplementation for 8 weeks showed enough to significantly increase blood levels of 25(OH)D. A significant difference in lipid profile was observed only in non-HDL cholesterol. Significant changes were observed in glucose homeostasis (fasting glucose and serum insulin) and, in addition, a reduction in the parameters of oxidative stress and DNA damage. There was a significant reduction in the values of 25(OH)D 4 weeks after the end of the supplementation, but levels still remained above baseline. Use of vitamin D supplementation can be an ally in the health modulation of patients with type 2 diabetes mellitus.

Effects of vitamin D as a regulator of androgen intracrinology in LNCAP prostate cancer cells

Prostate cancer is initially treated via androgen deprivation therapy (ADT), a highly successful treatment in the initial pursuit of tumor regression, but commonly restricted by the eventual emergence of a more lethal 'castrate resistant' form of the disease. Intracrine pathways that utilize dehydroepiandrosterone (DHEA) or other circulatory precursor steroids, are thought to generate relevant levels of growth-stimulating androgens such as testosterone (T) and dihydrotestosterone (DHT). In this study, we explored the capacity of the active vitamin D hormone to interact and elicit changes upon this prostatic intracrine pathway at a metabolic level. We used androgen dependent LNCaP cells cultured under steroid-depleted conditions and assessed the impact of vitamin D-based compounds upon intracrine pathways that convert exogenously added DHEA to relevant metabolites, through Mass Spectrometry (MS). Changes in relevant metabolism-related gene targets were also assessed. Our findings confirm that exposure to vitamin D based compounds, within LNCaP cells, elicits measurable and significant reduction in the intracrine conversion of DHEA to T, DHT and other intermediate metabolites within the androgenic pathway. The aassessment and validation of the biological model and analytical platforms were performed by pharmacological manipulations of the SRD5α and HSD-17β enzymes. The data provides further confirmation for how a vitamin D-based regime may be used to counter intracrine mechanisms contributing to the emergence of castrate-resistant tumors.

VDR agonists down regulate PI3K/Akt/mTOR axis and trigger autophagy in Kaposi's sarcoma cells

The Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor (KSHV/vGPCR) is a key molecule in the pathogenesis of Kaposi's sarcoma. We have previously shown that 1α,25(OH)2D3 or its less-calcemic analog TX 527 inhibits the proliferation of endothelial cells expressing vGPCR, NF-κB activity and induces apoptosis in a VDR dependent manner. In this work, we further explored whether 1α,25(OH)2D3 or TX 527 regulates PI3K/Akt/mTOR axis and induces autophagy as part of its antineoplastic mechanism of action. Proliferation assays indicated that vGPCR cell number decreased in presence of LY294002 (PI3K/Akt inhibitor) likewise 1α,25(OH)2D3 or TX 527 (10 nM, 48 h). Also, Akt phosphorylation was found decreased in dose (0.1-100 nM) and time response studies (12-72 h) after both compounds treatments. In addition, decreased phosphorylated Akt was significantly observed in the nucleus. Moreover, regulation of Akt phosphorylation was NF-κB and VDR dependent. TNFAIP3/A20, an ubiquitin-editing enzyme, a direct NF-κB target gene and a negative regulator of Beclin-1, was down-regulated whereas Beclin-1 was up-regulated after 10 nM of 1α,25(OH)2D3 or TX 527 treatment. Decrement in Akt phosphorylation was accompanied by a reduced mTOR phosphorylation and an increase in the autophagy marker LC3-II. Since increment in autophagosomes not always indicates increment in autophagy activity, we used Chloroquine (CQ, 1 μM), an inhibitor of autophagy flow, to confirm autophagy after both VDR agonists treatment. In conclusion, VDR agonists, 1α,25(OH)2D3 or TX 527, inhibited PI3K/Akt/mTOR axis and induced autophagy in endothelial cells expressing vGPCR by a VDR-dependent mechanism.

Association of Vitamin D Receptor Polymorphisms With Activity of Acromegaly, Vitamin D Status and Risk of Osteoporotic Fractures in Acromegaly Patients

Introduction: The vitamin D receptor (VDR) gene is one of the most widely studied tumorigenesis-related genes. The primary objective of this study was assessment of possible roles of VDR gene polymorphisms in acromegaly, with regard to the activity of the disease and compared them with a control group. Furthermore, we have assessed the associations between these polymorphisms with vitamin D status as well as with TBS (trabecular bone score) and risk for osteoporotic fracture in acromegaly patients. Materials and Methods: We studied 69 patients with acromegaly and 51 healthy controls (CG). Acromegaly patients were divided into three subgroups on the basis of disease activity (AA, active acromegaly; CD, controlled disease; CA, cured acromegaly). In all patients, blood samples were obtained to assess the hormonal and metabolic status as well as genetic analysis. VDR polymorphisms were determined by means of two methods, Polymerase Chain Reactions (PCR) and minisequencing (SNaPshot). Results: Genotype frequencies for VDR ApaI, TaqI, BsmI, and FokI polymorphisms did not deviate significantly from Hardy-Weinberg equilibrium (HWE) in the acromegaly group as well as in the control group. There was no statistically significant difference in distributions of these four VDR genotypes between acromegaly patients and the control group. This study revealed statistically significant negative correlation between risk of major osteoporotic fractures and genotypes tt (TaqI), aa (ApaI) and bb (BsmI) in acromegaly groups. Furthermore, the negative correlations were observed between TBS and risk for major osteoporotic fractures and hip fractures. Conclusions: Our study suggests that tt (TaqI), aa (ApaI) and bb (BsmI) of VDR gene may be associated with better bone quality and microarchitecture (higher TBS), which lead to a lower risk of osteoporotic fractures in acromegaly patients. TBS may be a useful tool for predicting risk of fractures in acromegaly patients.

Role of vitamin D and vitamin D receptor (VDR) in oral cancer

Oral cancer is known as one of the most common cancers, with a poor prognosis, related to delayed clinical diagnosis, either due to the lack of particular biomarkers related to the disease or costly therapeutic alternatives. Vitamin D executes its functions by interacting with the vitamin D receptor (VDR), both in healthy and diseased individuals, including oral cancer. This review discusses the role of vitamin D and VDR on tumorigenesis, emphasizing on oral cancer. Furthermore, regulation of VDR expression, mechanisms of anticancer effects of calcitriol, oral cancer chemoresistance and its relation with VDR and polymorphisms of VDR gene will be discussed. The manuscript is prepared mainly using the information collected from PubMed and MEDLINE.

Association of serum content of 25-hydroxy vitamin D with semen quality in normozoospermic and oligoasthenoteratozoospermic men

BACKGROUND

Vitamin D has multifaceted function in human reproductive physiology. It has been revealed that vitamin D is involved in spermatogenesis, and semen quality can be linked to vitamin D status in men.

OBJECTIVE

Evaluating the correlation of 25-hydroxy vitamin D (25-OHD) levels in serum with basic and advanced semen parameters and essential determinants of spermatozoa function.

MATERIALS AND METHODS

Participants were categorized, based on semen parameters, into normozoospermic (NS) and oligoasthenoteratozoospermic (OAT) men. Serum level of 25-OHD was measured. Apoptotic status of spermatozoa, mitochondrial membrane potential and reactive oxygen species content of semen were assessed.

RESULTS

Difference of 25-OHD concentration in serum of NS men versus OAT ones did not meet significance threshold. DNA fragmentation, reactive oxygen species content of semen and mitochondrial membrane potential state revealed significant difference between NS and OAT subjects. There were no significant differences in basic and functional semen parameters when men were stratified based on serum 25-OHD level. Taking both 25-OHD and semen categories (NS and OAT) into consideration did not indicate any significant difference in studied parameters. Total motility of spermatozoa was positively correlated with serum concentration of 25-OHD in all studied subjects. In addition, normal morphology of spermatozoa in NS men revealed a positive and significant correlation with levels of 25-OHD in serum.

CONCLUSION

Vitamin D may affect motility and morphology of spermatozoa. Lower content of serum vitamin D may affect fertility of men and should be considered in examination of men with abnormal spermogram.

BRAF signals to pro-apoptotic BIM to enhance AraC cytotoxicity induced in AML cells by Vitamin D-based differentiation agents

Vitamin D has so far not fulfilled its early promise as an antineoplastic agent, in spite of compelling in vitro data. With the aim of bringing vitamin D or its derivatives (VDDs) effectively to the clinic, we developed a two-pronged approach. First, by adding the plant-derived Carnosic Acid (CA) to a vitamin D2 derivative Doxercalciferol we increased its differentiation potency without increasing it hypercalcemic properties. Second, we added these two agents together to AML cells already treated with Cytarabine (AraC), the standard drug for the treatment of patients with AML. We now report that BRAF, a part of the MAPK signaling pathway, is required for the optimally increased cell death in this system and acts upstream of BIM, the regulator of the caspase cascade that leads to cell death by apoptosis. It is proposed that this therapeutic regimen should be tested in a clinical trial.

VDR mRNA overexpression is associated with worse prognostic factors in papillary thyroid carcinoma

The purpose of this study was to assess the relationship between vitamin D receptor gene (VDR) expression and prognostic factors in papillary thyroid cancer (PTC). mRNA sequencing and somatic mutation data from The Cancer Genome Atlas (TCGA) were analyzed. VDR mRNA expression was compared to clinicopathologic variables by linear regression. Tree-based classification was applied to find cutoff and patients were split into low and high VDR group. Logistic regression, Kaplan-Meier analysis, differentially expressed gene (DEG) test and pathway analysis were performed to assess the differences between two VDR groups. VDR mRNA expression was elevated in PTC than that in normal thyroid tissue. VDR expressions were high in classic and tall-cell variant PTC and lateral neck node metastasis was present. High VDR group was also associated with classic and tall cell subtype, AJCC stage IV and lower recurrence-free survival. DEG test reveals that 545 genes were upregulated in high VDR group. Thyroid cancer-related pathways were enriched in high VDR group in pathway analyses. VDR mRNA overexpression was correlated with worse prognostic factors such as subtypes of papillary thyroid carcinoma that are known to be worse prognosis, lateral neck node metastasis, advanced stage and recurrence-free survival.

Enhancement of arabinocytosine (AraC) toxicity to AML cells by a differentiation agent combination

Arabinocytosine (AraC, also known as cytarabine) is one of the mainstays of AML therapy, but like other DNA damaging therapeutic agents it is rarely curative by itself. There is an emerging realization that the therapeutic outcomes may be improved by combining AraC with other compounds. Here we report that the addition of a differentiating agent combination immediately following AraC damage to AML blasts, selectively increases the cell kill. The experiments were performed using cultured cells from established cell lines of AML (HL60 and U937). The cells were exposed to 100nM AraC, a concentration which produced approximately 25-50% cell kill, followed by a combination of 100nM 1alpha-hydroxyvitamin D2 (1-D2) and 10μM carnosic acid (CA), which together can serve as a powerful differentiating agent combination for AML cells, but are not toxic alone. AraC-induced cell death, measured by annexin V/propidium iodide, was significantly (p<0.01) increased by the 1-D2/CA combination in both cell lines, but not by 1-D2 or CA alone. The enhancement of cell death occurred by both apoptosis and necrosis, was associated with increased DNA damage and with higher levels of DNA damage response (DDR) activated marker Chk1, but the expression of p27, a cell cycle inhibitor protein, was not enhanced by 1-D2/CA. The principal finding is that a vitamin D analog 1-D2 combined with a plant-derived antioxidant CA can markedly augment the cytotoxic action of AraC, an anti-leukemia therapeutic agent.

Could Vitamin D Analogues Be Used to Target Leukemia Stem Cells?

Leukemic stem cells (LSCs) are defined as cells that possess the ability to self-renew and give rise to the differentiated cancer cells that comprise the tumor. These LSCs seem to show chemo-resistance and radio-resistance leading to the failure of conventional cancer therapies. Current therapies are directed at the fast growing tumor mass leaving the LSC fraction untouched. Eliminating LSCs, the root of cancer origin and recurrence, is considered to be a hopeful approach to improve survival or even to cure cancer patients. In order to achieve this, the characterization of LSCs is a prerequisite in order to develop LSC-based therapies to eliminate them. Here we review if vitamin D analogues may allow an avenue to target the LSCs.

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

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

Vitamin D3-dependent VDR signaling delays ron-mediated breast tumorigenesis through suppression of β-catenin activity

The Ron receptor is upregulated in human breast cancers and correlates with enhanced metastasis and reduced patient survival. Ron overexpression drives mammary tumorigenesis through direct β-catenin activation and augmented tumor cell proliferation, migration and invasion. Ron and β-catenin are also coordinately elevated in breast cancers. The vitamin D receptor (VDR) antagonizes β-catenin signaling. Herein, we examined mammary tumor onset and progression using a Ron-driven murine model of breast tumorigenesis crossed with VDR deficient mice. VDR ablation accelerated mammary tumor onset and led to tumors that exhibited a desmoplastic phenotype and enhanced metastases. Tumor levels of active β-catenin were markedly increased in the absence of VDR. In vitro, VDR activation in breast cancer cells reduced β-catenin activation and transcriptional activity leading to elevated expression of the extracellular Wnt inhibitor dickkopf-related protein 1, and a reduction in the interaction of β-catenin with the cyclin D1 promoter. Expression of a stabilized form or β-catenin ablated the protective effects of VDR activation. Collectively, these studies delineate a protective role for VDR signaling in Ron-induced mammary tumorigenesis through disruption of β-catenin activation.

DNA Repair in Despair-Vitamin D Is Not Fair

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

Prevalence of Vitamin D deficiency in Pakistan and implications for the future

BACKGROUND AND AIMS

vitamin D deficiency (25-hydroxyvitamin D) affects over one billion people worldwide. Vitamin D deficiency results in progression of osteoporosis as well as other conditions. Previous studies have shown high rates of vitamin D deficiency in Pakistan despite appreciable levels of sunshine. However, none have assessed vitamin D deficiency across all age groups, genders, incomes, and locations to guide future strategies.

METHODS

Questionnaire and blood sampling among 4830 randomly selected citizens.

RESULTS

High levels of deficiency among all age groups, genders, income levels, and locations. Amongst the selected citizens, 53.5% had vitamin D deficiency, 31.2% had insufficient vitamin D, and only 15.3% normal vitamin D.

CONCLUSION

High rates of vitamin D deficiency in Pakistan despite high levels of sunshine and previous Food Acts asking for food fortification with vitamin D. Public health strategies are needed to address high deficiency rates, including food fortification, i.e. nurture, alongside increasing exposure to sunlight, i.e. nature. This will involve all key stakeholder groups.

A novel cytostatic form of autophagy in sensitization of non-small cell lung cancer cells to radiation by vitamin D and the vitamin D analog, EB 1089

The standard of care for unresectable lung cancer is chemoradiation. However, therapeutic options are limited and patients are rarely cured. We have previously shown that vitamin D and vitamin D analogs such as EB 1089 can enhance the response to radiation in breast cancer through the promotion of a cytotoxic form of autophagy. In A549 and H460 non-small cell lung cancer (NSCLC) cells, 1,25-D3 (the hormonally active form of vitamin D) and EB 1089 prolonged the growth arrest induced by radiation alone and suppressed proliferative recovery, which translated to a significant reduction in clonogenic survival. In H838 or H358 NSCLC cells, which lack VDR/vitamin D receptor or functional TP53, respectively, 1,25-D3 failed to modify the extent of radiation-induced growth arrest or suppress proliferative recovery post-irradiation. Sensitization to radiation in H1299 NSCLC cells was evident only when TP53 was induced in otherwise tp53-null H1299 NSCLC cells. Sensitization was not associated with increased DNA damage, decreased DNA repair or an increase in apoptosis, necrosis, or senescence. Instead sensitization appeared to be a consequence of the conversion of the cytoprotective autophagy induced by radiation alone to a novel cytostatic form of autophagy by the combination of 1,25-D3 or EB 1089 with radiation. While both pharmacological and genetic suppression of autophagy or inhibition of AMPK phosphorylation sensitized the NSCLC cells to radiation alone, inhibition of the cytostatic autophagy induced by the combination treatment reversed sensitization. Evidence for selectivity was provided by lack of radiosensitization in normal human bronchial cells and cardiomyocytes. Taken together, these studies have identified a unique cytostatic function of autophagy that appears to be mediated by VDR, TP53, and possibly AMPK in the promotion of an enhanced response to radiation by 1,25-D3 and EB 1089 in NSCLC.

A synthetic lethal screen identifies the Vitamin D receptor as a novel gemcitabine sensitizer in pancreatic cancer cells

Overcoming chemoresistance of pancreatic cancer (PCa) cells should significantly extend patient survival. The current treatment modalities rely on a variety of DNA damaging agents including gemcitabine, FOLFIRINOX, and Abraxane that activate cell cycle checkpoints, which allows cells to survive these drug treaments. Indeed, these treatment regimens have only extended patient survival by a few months. The complex microenvironment of PCa tumors has been shown to complicate drug delivery thus decreasing the sensitivity of PCa tumors to chemotherapy. In this study, a genome-wide siRNA library was used to conduct a synthetic lethal screen of Panc1 cells that was treated with gemcitabine. A sublethal dose (50 nM) of the drug was used to model situations of limiting drug availability to PCa tumors in vivo. Twenty-seven validated sensitizer genes were identified from the screen including the Vitamin D receptor (VDR). Gemcitabine sensitivity was shown to be VDR dependent in multiple PCa cell lines in clonogenic survival assays. Sensitization was not achieved through checkpoint override but rather through disrupting DNA repair. VDR knockdown disrupted the cells' ability to form phospho-γH2AX and Rad51 foci in response to gemcitabine treatment. Disruption of Rad51 foci formation, which compromises homologous recombination, was consistent with increased sensitivity of PCa cells to the PARP inhibitor Rucaparib. Thus inhibition of VDR in PCa cells provides a new way to enhance the efficacy of genotoxic drugs.

Investigation of Bone Health Subsequent to Vitamin D Supplementation in Children Following Burn Injury

BACKGROUND

The effect of supplemental vitamin D on fracture occurrence following burn injuries is unclear. The objective of this study was to evaluate postintervention incidence of fractures in children during the rehabilitative phase postburn (PB) following participation in a randomized clinical trial of vitamin D supplementation.

MATERIALS AND METHODS

Follow-up for fracture evaluation was obtained in 39 of 50 patients randomized to daily enteral vitamin D2, D3, or placebo throughout the acute burn course. Serum 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, D2, D3, calcitonin, and bone alkaline phosphatase (BAP) measurements were obtained PB day 7, midpoint, discharge, and 1-year PB. Urinary calcium was obtained PB day 7 and midpoint. Dual-energy x-ray absorptiometry (DXA) was performed at discharge and 1-year PB.

RESULTS

Fractures were reported in 6 of 39 respondents. Four fractures occurred in the placebo group, 2 in the D2 group, and none in the D3 group. Serum vitamin D, calcitonin, BAP, and urinary calcium were similar between fracture groups. The group with fracture morbidity had larger burn size (83.8% ± 4.9% vs 53.0% ± 2.9%, P < .0001), greater full-thickness burn (69.7% ± 9.4% vs 39.4% ± 4.1%, P = .02), and increased incidence of inhalation injury (33% vs 6%, P = .04). Decreased bone mineral density z score was noted at discharge in the placebo fracture compared with no-fracture group (P < .05).

CONCLUSION

This preliminary report suggests there may be benefit of vitamin D3 in reducing postdischarge fracture risk. Results reaffirm the importance of monitoring bone health in pediatric patients postburn.

Potent antiproliferative effects of 25-hydroxy-16-ene-23-yne-vitamin D₃ that resists the catalytic activity of both CYP27B1 and CYP24A1

The potency of 25-hydroxyvitamin D3 (25(OH)D3) is increased by several fold through its metabolism into 1α,25-dihydroxyvitamin D3 (1α,25(OH)2D3) by cytochrome P450 27B1 (CYP27B1). Thus, the pivotal role of 1α-hydroxylation in the activation of vitamin D compounds is well known. Here, we examined the metabolism of 25-hydroxy-16-ene-23-yne-vitamin D3 (25(OH)-16-ene-23-yne-D3), a synthetic analog of 25(OH)D3 in a cell-free system and demonstrated that 25(OH)-16-ene-23-yne-D3 is neither activated by CYP27B1 nor inactivated by cytochrome P450 24A1 (CYP24A1). These findings were also confirmed in immortalized normal human prostate epithelial cells (PZ-HPV-7) which are known to express both CYP27B1 and CYP24A1, indicating that the structural modifications featured in 25(OH)-16-ene-23-yne-D3 enable the analog to resist the actions of both CYP27B1 and CYP24A1. To provide intelligible structure-function information, we also performed molecular docking analysis between the analog and CYP27B1. Furthermore, 25(OH)-16-ene-23-yne-D3 was found to suppress the growth of PZ-HPV-7 cells with a potency equivalent to 1α,25(OH)2D3. The antiproliferative activity of 25(OH)-16-ene-23-yne-D3 was found to be vitamin D receptor (VDR)-dependent as it failed to inhibit the growth of mammary tumor cells derived from VDR-knockout mice. Furthermore, stable introduction of VDR into VDR-knockout cells restored the growth inhibition by 25(OH)-16-ene-23-yne-D3. Thus, we identified 25-hydroxy-16-ene-23-yne-vitamin D3 as a novel non-1α-hydroxylated vitamin D analog which is equipotent to 1α,25(OH)2D3 in its antiproliferative activity. We now propose that the low potency of the intrinsic VDR-mediated activities of 25(OH)D3 can be augmented to the level of 1α,25(OH)2D3 without its activation through 1α-hydroxylation by CYP27B1, but by simply preventing its inactivation by CYP24A1.

Dietary vitamin D supplementation does not reduce the incidence or severity of asbestos-induced mesothelioma in a mouse model

Epidemiological studies suggest that vitamin and mineral intake is associated with cancer incidence. A prevention strategy based on diet or dietary supplementation could have enormous benefit, both directly, by preventing disease, and indirectly by alleviating fear in millions of people worldwide who have been exposed to asbestos. We have previously shown that dietary supplementation with the antioxidants vitamins A, E, and selenium does not affect overall survival nor the time to progression of asbestos-induced mesothelioma in MexTAg mice. Here we have extended our analysis to vitamin D. We compared survival of asbestos-exposed MexTAg mice provided with diets that were deficient or supplemented with 4500 IU/kg vitamin D (cholecalciferol). Survival of supplemented mice was significantly shorter than mice given a standard AIN93 diet containing 1000 IU/kg cholecalciferol (median survival was 29 and 32.5 weeks respectively). However, mice deficient in vitamin D had the same rate of mesothelioma development as control mice. Neither the latency time from asbestos exposure to diagnosis nor disease progression after diagnosis were significantly different between mice on these diets. We conclude that vitamin D is unlikely to moderate the incidence of disease in asbestos-exposed populations or to ameliorate the pathology in patients with established mesothelioma.

1,25-Dihydroxyvitamin D₃ and cisplatin synergistically induce apoptosis and cell cycle arrest in gastric cancer cells

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] plays an anticancer role in multiple types of cancer and potentiates the cytotoxic effects of several common chemotherapeutic agents. The hypercalcemia caused by 1,25(OH)2D3 alone or resistance to cisplatin weaken the anticancer effects of vitamin D. Thus, in this study, we aimed to investigate the synergistic effects of 1,25(OH)2D3 and cisplatin on the apoptosis and cell cycle progression of gastric cancer cells. BGC-823 human gastric cancer cells were treated with 1,25(OH)2D3 or cisplatin alone, or a combination of both agents. Cell apoptosis was assessed by TUNEL assay and flow cytometry. The expression of the apoptosis-related proteins, poly(ADP-ribose) polymerase (PARP), Bax, Bcl-2, caspase-3 and caspase-8, was examined using immunoblot analysis. ERK and AKT phosphorylation were examined by immunoblot analysis. The cell cycle distribution was determined by propidium iodide staining and flow cytometric analysis. p21 and p27 protein expression was also examined using immunoblot analysis. Our results revealed that co-treatment with 1,25(OH)2D3 enhanced cisplatin-induced apoptosis and upregulated the expression of Bax, and promoted the cleavage of PARP and caspase-3. The phosphorylation levels of ERK and AKT were reduced following combined treatment with 1,25(OH)2D3 and cisplatin. The percentage of cells in the G0/G1 phase was greater in the cells treated with the combined treatment than in those treated with either 1,25(OH)2D3 or cisplatin alone. p21 and p27 expression was upregulated following co-treatment with both agents. The results of this study suggest that 1,25(OH)2D3 potentiates cisplatin-mediated cell growth inhibition and cell apoptosis, which involves the upregulation of Bax, a decrease in ERK and AKT phosphorylation levels, and increased p21 and p27 levels.

1α,25-dihydroxyvitamin D3 modulates CYP2R1 gene expression in human oral squamous cell carcinoma tumor cells

Oral squamous cell carcinomas (OSCC) are the most common malignant neoplasms associated with mucosal surfaces of the oral cavity and oropharynx. 1α,25-Dihydroxyvitamin D3 (1,25(OH)2D3) is implicated as an anticancer agent. Cytochrome P450 2R1 (CYP2R1) is a microsomal vitamin D 25-hydroxylase which plays an important role in converting dietary vitamin D to active metabolite, 25-(OH)D3. We identified high levels of CYP2R1 expression using tissue microarray of human OSCC tumor specimens compared to normal adjacent tissue. Therefore, we hypothesize that 1,25(OH)2D3 regulates CYP2R1 gene expression in OSCC tumor cells. Interestingly, real-time RT-PCR analysis of total RNA isolated from OSCC cells (SCC1, SCC11B, and SCC14a) treated with 1,25(OH)2D3 showed a significant increase in CYP2R1 and vitamin D receptor (VDR) mRNA expression. Also, Western blot analysis demonstrated that 1,25(OH)2D3 treatment time-dependently increased CYP2R1 expression in these cells. 1,25(OH)2D3 stimulation of OSCC cells transiently transfected with the hCYP2R1 promoter (-2 kb)-luciferase reporter plasmid demonstrated a 4.3-fold increase in promoter activity. In addition, 1,25(OH)2D3 significantly increased c-Fos, p-c-Jun expression, and c-Jun N-terminal kinase (JNK) activity in these cells. The JNK inhibitor suppresses 1,25(OH)2D3, inducing CYP2R1 mRNA expression and gene promoter activity in OSCC cells. Furthermore, JNK inhibitor significantly decreased 1,25(OH)2D3 inhibition of OSCC tumor cell proliferation. Taken together, our results suggest that AP-1 is a downstream effector of 1,25(OH)2D3 signaling to modulate CYP2R1 gene expression in OSCC tumor cells, and vitamin D analogs could be potential therapeutic agents to control OSCC tumor progression.

Synthesis and Biological Activity of Diastereomeric and Geometric Analogs of Calcipotriol, PRI-2202 and PRI-2205, Against Human HL-60 Leukemia and MCF-7 Breast Cancer Cells

Diastereomeric and geometric analogs of calcipotriol, PRI-2202 and PRI-2205, were synthesized as advanced intermediates from vitamin D C-22 benzothiazoyl sulfones and side-chain aldehydes using our convergent strategy. Calcitriol, calcipotriol (PRI-2201) and tacalcitol (PRI-2191) were used as the reference compounds. Among a series of tested analogs the diastereomeric analog PRI-2202 showed the strongest antiproliferative activity on the human breast cancer cell line MCF-7, whereas the geometric analog PRI-2205 was the weakest. Both analogs were less potent in antiproliferative activity against HL-60 cells compared to the reference compounds. The ability to potentiate antiproliferative effect of cisplatin or doxorubicin against HL-60 cells or that of tamoxifen against the MCF-7 cell line was observed at higher doses of PRI-2202 or PRI-2205 than those of the reference compounds. The proapoptotic activity of tamoxifen, expressed as the diminished mitochondrial membrane potential, as well as the increased phosphatidylserine expression, was partially attenuated by calcitriol, PRI-2191, PRI-2201 and PRI-2205. The treatment of the MCF-7 cells with tamoxifen alone resulted in an increase in VDR expression. Moreover, a further increase in VDR expression was observed when the analogs PRI-2201 or PRI-2205, but not PRI-2191, were used in combination with tamoxifen. This observation could partially explain the potentiation of the antiproliferative effect of tamoxifen by vitamin D analogs.

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.

Influence of vitamin D on cisplatin sensitivity in testicular germ cell cancer-derived cell lines and in a NTera2 xenograft model

The active form of vitamin D, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) has anti-proliferative, pro-apoptotic, and pro-differentiating effects in somatic cancer cells in vitro and in vivo. 1,25(OH)2D3 also augments the anti-tumor effects of several chemotherapeutic agents, including cisplatin, which may have clinical relevance. Given the pro-differentiation effect of vitamin D recently demonstrated in testicular germ cell tumors (TGCTs), we hypothesized that 1,25(OH)2D3 could be a beneficial adjunctive to existing chemotherapy regime used to treat these tumors. In this study, cell survival effects of 1,25(OH)2D3, another pro-differentiation compound, retinoic acid and cisplatin were investigated in TGCT-derived cell lines in vitro. 1,25(OH)2D3 augmented the effect of cisplatin in an embryonal carcinoma-derived cell line (NTera2), possibly through downregulation of pluripotency genes and simultaneous upregulation of the cell cycle regulators p21, p27, p53, p73 and FOXO1, while no significant effects were found in TCam-2 and 2102Ep cell lines (derived from seminoma and embryonal carcinoma, respectively). Anti-tumor effects of cholecalciferol, 1,25(OH)2D3, and cisplatin were subsequently tested in vivo, in a NTera2 xenograft tumor model in nude mice. In xenograft tumors, co-treatment with 1,25(OH)2D3 and cisplatin resulted in downregulation of OCT4 and simultaneous upregulation of p21 and p73, but did not reduce tumor growth significantly more than cisplatin alone. Also, cholecalciferol supplemented diet (1100IU daily) after tumor formation did not increase cisplatin sensitivity in vivo. In conclusion, addition of 1,25(OH)2D3 augmented the antitumor effect of cisplatin monotherapy in vitro, but not in this in vivo testicular germ cell cancer model. Future studies are needed to investigate potential beneficial effects of vitamin D with lower cisplatin doses, and to determine whether 1,25(OH)2D3 may increase cisplatin sensitivity in chemotherapy-resistant TGCTs. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Vitamin D analogs enhance the anticancer activity of 5-fluorouracil in an in vivo mouse colon cancer model

Background

Active vitamin D analogs that are less toxic than calcitriol can be useful in the combined treatment of patients suffering from colon cancer. In the present study we demonstrate, for the first time in an in vivo model system, the biological effect of combined therapy using 5-fluorouracil (5-FU) along with vitamin D analog PRI-2191 (tacalcitol, 1,24-dihydroxyvitamin D₃) or PRI-2205 (5,6-trans-isomer of calcipotriol) on colon cancer.

Methods

We investigated the influence of vitamin D analogs on the anticancer activity of 5-FU or capecitabine in the treatment of mice bearing MC38 mouse colon tumors implanted subcutaneously or orthotopically. The cell cycle distribution, E-cadherin expression and caspase 3/7 activity in vitro were also evaluated.

Results

We observed that both PRI-2191 and PRI-2205 significantly enhanced the antitumor activity of 5-FU; but these results depend on the treatment regimen. Applying the optimal schedule of combined therapy we observed a significant decrease in tumor growth, metastasis and also a prolongation of the survival time of mice, in comparison with the administrations of 5-FU given alone. Both combinations indicated a synergistic effect and did not cause toxicity. Moreover, analogs applied after completed course of administration of 5-FU, prolonged the antitumor effect of the drug. Furthermore, when the prodrug of 5-FU, capecitabine, was used, potentiation of its activity was also observed.

Conclusions

Our data suggest that vitamin D analogs (especially PRI-2191) might be potentially applied to clinical use in order to enhance the anticancer effect of 5-FU and also prolong its activity against colon cancer. The activity of PRI-2191 is realized through stopping the cells in the G₀/G₁ cell cycle phase and increasing the expression of E-cadherin.

Progesterone enhances calcitriol antitumor activity by upregulating vitamin D receptor expression and promoting apoptosis in endometrial cancer cells

Human studies suggest that progesterone and calcitriol may prove beneficial in preventing or inhibiting oncogenesis, but the underlying mechanism is not fully understood. The current study investigates the effects of progesterone, calcitriol, and their combination on immortalized human endometrial epithelial cells and endometrial cancer cells and identifies their targets of action. Combination treatment with both agents enhanced vitamin D receptor expression and inhibited cell proliferation through caspase-3 activation and induction of G0-G1 cell-cycle arrest with associated downregulation of cyclins D1 and D3 and p27 induction. We used mass spectrometry-based proteomics to measure protein abundance differences between calcitriol-, progesterone-, or combination-exposed endometrial cells. A total of 117 proteins showed differential expression among these three treatments. Four proteins were then selected for validation studies: histone H1.4 (HIST1H1E), histidine triad nucleotide-binding protein 2 (HINT2), IFN-induced, double-stranded RNA-activated protein kinase (EIF2AK2), and Bcl-2-associated X protein (BAX). Abundance levels of selected candidates were low in endometrial cancer cell lines versus the immortalized endometrial epithelial cell line. All four proteins displayed elevated expression in cancer cells upon exposure to calcitriol, progesterone, or the combination. Further BAX analysis through gain- or loss-of-function experiments revealed that upregulation of BAX decreased cell proliferation by changing the BAX:BCL-2 ratio. Knockdown of BAX attenuated progesterone- and calcitriol-induced cell growth inhibition. Our results showed that progesterone and calcitriol upregulate the expression of BAX along with other apoptosis-related proteins, which induce inhibition of endometrial cancer cell growth by apoptosis and cell-cycle arrest.