Vitamin D Receptor Levels Research Articles

Role of Vitamin D Receptor in Prediabetes

Background: Recent epidemiological evidence points towards the potential association of vitamin D insufficiency with adverse metabolic risk and in the pathogenesis of cancer, cardiovascular diseases, type 2 diabetes and other diseases. Vitamin D exerts its action in a variety of cell types through vitamin D receptors. No reports are available in the literature regarding vitamin D and vitamin D receptor status in prediabetics. The present study was planned to compare serum 25-hydroxy vitamin D [25(OH)D] and vitamin D receptor (VDR) protein levels in prediabetic cases and normoglycemic controls. Methods: The present study was conducted in 80 persons who were divided into two groups, Study group (n= 40) comprised of diagnosed cases of prediabetes and control group (n=40) comprised of healthy normoglycemic controls. Serum 25-hydroxy vitamin D [25(OH)D] was analyzed by radioimmunoassay (RIA). Serum vitamin D receptor (VDR) protein was analyzed by sandwich enzyme immunoassay (ELISA). Results: Serum 25(OH) vitamin D levels were significantly decreased in prediabetic cases as compared to normoglycemic controls [p<0.001]. Serum Vitamin D receptor protein levels were highly significantly decreased in prediabetic cases as compared to normoglycemic controls [p<0.00]. Serum 25(OH)D levels showed a highly significant positive correlation with serum VDR levels in both the groups [p<0.001 at both levels]. Conclusion: The findings of the present study indicate that vitamin D and VDR can serve as a possible screening marker and target for modulation of the management and alleviating the progress and complications of diabetes.

The clinical significance of VDR and WIFI downregulation in colorectal cancer tissue

BackgroundActivation of the Wnt/β catenin signaling pathway is the first event in the majority of colorectal cancers. Wnt inhibitory factor 1 (WIF1) inhibits the activity Wnt/β catenin pathway and prevents tumor growth through binding Wnt ligands. Vitamin D Receptor (VDR) modulates the transcription rate hundreds of target genes, specifically those involved in the inhibition of the Wnt/β catenin pathway. In this study, we aimed to analyze the expression of VDR and WIFI in patients with sporadic CRC. MethodsOur study population consisted of 47 sporadic CRC tissues and their neighboring non-cancerous tissues that were collected between 2006 and 2015. RNA extraction was performed by RNX-plus Total RNA Isolation Kit from tissues. After cDNA synthesis; the real-time PCR was performed to detect VDR and WIFI gene expression. ResultsOur experiments revealed the mRNA expression levels of VDR and WIF1 were markedly lower in tumoral tissues in compared their marginal tissues, especially in the stage of III and stage IV (p-value <0.0001). In addition, there was statistically a positive correlation between VDR and WIFI expressions in tumoral tissues (r = 0.9329, p-value < 0.0001). ConclusionOur findings indicated that expression levels of VDR and WIF1 was low in CRC tissues in comparison with marginal tissues. Thereby, VDR and WIFI may be considered as critical factors which may be associated with different stages of CRC, and it can be novel biomarkers for the diagnosis and prognosis of CRC, as well as can be a promising therapeutic target in CRC.

The vitamin D receptor Taq I polymorphism is associated with reduced VDR and increased PDIA3 protein levels in human intestinal fibroblasts

The synonymous single nucleotide polymorphism (SNP) rs731236, located in the vitamin D receptor (VDR) gene (Taq I) has been associated with both decreased levels of the protein in peripheral blood mononuclear cells and a fibrosis-related complication in Crohn´s disease (CD). Interactions between VDR and a protein-disulfide isomerase-associated 3 (PDIA3) in the regulation of extracellular matrix have been reported and we aim to analyze the relevance of the VDR genotypes and the effects of Vitamin D (VD) in the expression of VDR, PDIA3 and proliferation of intestinal fibroblasts. Human intestinal fibroblasts were isolated from the non-affected surgical resections of colorectal patients and classified according to the VDR genotype. In some cases, cells were transfected with specific PDIA3 siRNA. Basal and VD-stimulated expression of VDR, PDIA3 and Collagen 1A1 (COL1A1) as well as fibroblast migration/proliferation were analyzed. Our data show that intestinal fibroblasts homozygous for the C allele in the VDR gene exhibited lower VDR protein levels and higher proliferation than cells homozygous for the T allele. VD increased VDR and attenuated the accelerated proliferation of CC fibroblasts. The diminished VDR level detected in CC cells was associated with increased levels of both PDIA3 and COL1A1 expression and the transient silencing of PDIA3 significantly reduced COL1A1 expression. We conclude that intestinal fibroblasts homozygous for the C allele in the VDR gene exhibited: reduced VDR protein levels, increased proliferation and increased PDIA3/COL1A1 expression. Treatment with VD increased VDR and attenuated proliferation of these cells.

Assessment of expression of vitamin D receptor-associated lncRNAs in gastric cancer

Vitamin D deficiency and alterations in expression of vitamin D receptor (VDR) are involved in the pathogenesis of gastric cancer. In the current study, we assessed expression of VDR and four VDR-associated long non-coding RNAs (SNHG6, SNHG16, LINC00346 and LINC00511) in gastric cancer tissues and their neighboring non-cancerous tissues by means of real time PCR. Expression levels of VDR and SNHG6 were significantly higher in malignant tissues compared with non-malignant tissues (expression ratios: 32.7 and 3.39, P values: 0.04 and <0.001 respectively). There was no significant difference in expression of other genes between malignant and non-malignant tissues. There was a trend toward association between expression level of VDR and patients' gender (P = .05). Besides, expression of SNHG6 was associated with peritoneal invasion (P = .01). Expression of SNHG6 was significantly higher in patients who had family history of cancer compared with those did not (P = .04). Expression of SNHG16 was lower in samples with peritoneal invasion compared with those did not have peritoneal invasion (P = .04). Finally, expression of VDR was higher in malignant samples of females compared with males (P = .009). Expressions of other genes were not different between subgroups of malignant samples. Expression levels of VDR and SNHG6 could differentiate malignant and non-malignant tissues with diagnostic power of 0.85. The current study demonstrates the role of VDR signaling in gastric cancer.

RNA-binding protein HuR regulates translation of vitamin D receptor modulating rapid epithelial restitution after wounding.

Homeostasis of the intestinal epithelium is tightly regulated by numerous extracellular and intracellular factors including vitamin D and the vitamin D receptor (VDR). VDR is highly expressed in the intestinal epithelium and is implicated in many aspects of gut mucosal pathophysiology, but the exact mechanism that controls VDR expression remains largely unknown. The RNA-binding protein human antigen R (HuR) regulates the stability and translation of target mRNAs and thus modulates various cellular processes and functions. Here we report a novel role of HuR in the posttranscriptional control of VDR expression in the intestinal epithelium. The levels of VDR in the intestinal mucosa decreased significantly in mice with ablated HuR, compared with control mice. HuR silencing in cultured intestinal epithelial cells (IECs) also reduced VDR levels, whereas HuR overexpression increased VDR abundance; neither intervention changed cellular Vdr mRNA content. Mechanistically, HuR bound to Vdr mRNA via its 3'-untranslated region (UTR) and enhanced VDR translation in IECs. Moreover, VDR silencing not only inhibited IEC migration over the wounded area in control cells but also prevented the increased migration in cells overexpressing HuR, although it did not alter IEC proliferation in vitro and growth of intestinal organoids ex vivo. The human intestinal mucosa from patients with inflammatory bowel diseases exhibited decreased levels of both HuR and VDR. These results indicate that HuR enhances VDR translation by directly interacting with its mRNA via 3'-UTR and that induced VDR by HuR is crucial for rapid intestinal epithelial restitution after wounding.

Vitamin D modulates innate immunity in pulmonary tuberculosis

Abstract Vitamin D and vitamin D receptor (VDR) may play role in altering host defence against Mtb via cathelicidin production and regulating nitric oxide (NO) production through inducible nitric oxide synthase (iNOS). 100 active pulmonary tuberculosis (PTB) patients, 75 household contacts and 70 healthy controls were recruited. Serum Vitamin D and NO levels were measured using CLIA and colorimetry based kit respectively. VDR and iNOS mRNA was studied in monocytes using qPCR. Serum VDR, cathelicidin and iNOS levels were measured using ELISA. Lower serum levels of vitamin D was found in PTB group compared to household contacts and healthy controls (P&amp;lt;0.001). VDR (both mRNA and protein) and iNOS mRNA levels were also lower in PTB group compared to household contacts and healthy controls (P&amp;lt;0.005)probably due to decreased levels of vitamin D. However, despite low serum vitamin D, serum cathelicidin levels were higher in PTB group compared to household contacts and healthy controls (p&amp;lt;0.01) which could be attributed to direct trigger via toll like receptors where Mtb is multiplying actively. Serum iNOS and NO levels were higher in PTB group compared to household contacts and healthy controls (p&amp;lt; 0.05), despite decreased iNOS expression which needs further evaluation. Increased VDR and iNOS expression in household contacts compared to both PTB and healthy controls could be due to optimum levels of vitamin D along with some exposure to Mtb as evident by increased levels of cathelicidin and NO compared to healthy controls. Adequate levels of vitamin D, VDR and iNOS that in turn promote production of antimicrobial cathelicidin and NO might have protective role against TB among household contacts and needs further investigation for its therapeutic potential.

Vitamin D regulation of HAS2, hyaluronan synthesis and metabolism in triple negative breast cancer cells

The vitamin D receptor (VDR) and its ligand 1,25(OH)2D3 (1,25D) exert anti-tumor effects, but considerable heterogeneity has been reported in different model systems. In general, cell lines derived from aggressive tumor subtypes such as Triple Negative Breast Cancer (TNBC) express low levels of VDR and are less sensitive to 1,25D than those derived from more differentiated tumor types. We have previously reported that 1,25D inhibits hyaluronic acid synthase 2 (HAS2) expression and hyaluronic acid (HA) synthesis in murine TNBC cells. Here we confirmed the inhibitory effect of 1,25D on HA synthesis in human Hs578T cells representative of the mesenchymal/stem-like (MSL) subtype of TNBC. Because HA synthesis requires the production of hexoses for incorporation into HA, we predicted that the high HA production characteristic of Hs578T cells would require sustained metabolic changes through the hexosamine biosynthetic pathway (HBP). We thus examined metabolic gene expression in Hs578T cell variants sorted for High (HAHigh) and Low (HALow) HA production, and the ability of 1,25D to reverse these adaptive changes. HAHigh populations exhibited elevated HA production, smaller size, increased proliferation and higher motility than HALow populations. Despite their more aggressive phenotype, HAHigh populations retained expression of VDR protein at levels comparable to that of parental Hs578T cells and HALow subclones. Treatment with 1,25D decreased production of HA in both HAHigh and HALow populations. We also found that multiple metabolic enzymes were aberrantly expressed in HAHigh cells, especially those involved in glutamine and glucose metabolism. Notably, Glutaminase (GLS), a known oncogene for breast cancer, was strongly upregulated in HAHigh vs. HALow cells and its expression was significantly reduced by 1,25D (100 nM, 24 h). Consistent with this finding, Seahorse extracellular flux analysis indicated that respiration in HAHigh cells was significantly more dependent on exogenous glutamine than HALow cells, however, acute 1,25D exposure did not alter metabolic flux. In contrast to GLS, the glutamate transporter SLC1A7 was significantly reduced in HAHigh cells compared to HALow cells and its expression was enhanced by 1,25D. These findings support the concept that 1,25D can reverse the metabolic gene expression changes associated with HA production in cancer cells with aggressive phenotypes.

Plasma 25-Hydroxyvitamin D Levels and VDR Gene Expression in Peripheral Blood Mononuclear Cells of Leukemia Patients and Healthy Subjects in Central Kazakhstan.

Low blood levels of the vitamin D metabolite 25-hydroxyvitamin D [25(OH)D] have been associated with an increased risk and poorer outcomes of various cancers, including hematological malignancies. The Central Kazakhstan area has a relatively high incidence rate of leukemia. However, the relationship between vitamin D status and leukemia or other types of cancer in Kazakhstan has not yet been addressed. Therefore, in this first pilot single-center study conducted in Central Kazakhstan, we compared plasma levels of 25(OH)D and the vitamin D receptor (VDR) gene expression levels in peripheral blood mononuclear cells of patients with leukemia and demographically matching healthy volunteers. The levels of 25(OH)D in patients were found to be significantly lower (10.8 ± 7.0 ng/mL; n = 31) than in healthy subjects (21.6 ± 7.8 ng/mL; n = 34; p < 0.0001). A similar difference was observed in both younger (<60 years old) and older (>60 years old) participants, though there was no association between 25(OH)D concentration and age within the patient group. In female patients, 25(OH)D levels were significantly lower than in male patients (p = 0.04). No significant seasonal variations of 25(OH)D were observed in either the patient or the control group. VDR gene expression levels appeared to be similar in leukemia patients and healthy subjects, and no correlation between the cellular VDR expression and plasma 25(OH)D concentrations was observed in either group of participants. We did not observe a significant association of 25(OH)D or VDR levels and overall survival of leukemia patients. This observational study conducted for the first time in Kazakhstan supports previous findings demonstrating reduced blood 25(OH)D levels in cancer (leukemia) patients. Larger studies are required to determine whether low 25(OH)D plasma concentrations represent a risk factor for leukemia development and/or progression.

The Role of IL-6, TNF-α, and VDR in Inhibiting the Growth of Salmonella Typhi: in vivo Study

Background and aim: The prevalence of typhoid fever is reportedly high, especially in Asia. When a pathogen enters the human body, there are markers in the form of molecules that will be known by the innate immune system. Specific molecular markers of gram negative bacteria, which are Lipopolysaccharides (LPS) and Toll-Like receptors-4 will interact with LPS. The binding between LPS and TLR-4 will give rise to activation signals that will activate innate immune cells. Immune cells will release a number of proinflammatory cytokines, such as TNF-α, IL-1, and IL-6. While Vitamin D Receptors (VDR) are expressed in large amounts in tumor tissue and infected cells. This study aimed to prove the role of IL-6, TNF-α, and VDR in inhibiting bacterial growth in mice that have been induced by S.Typhi. Methods: This research was a real experimental pre-post test design to investigate the level of IL-6, TNF-α and VDR in suppressing the growth of bacteria in the peritoneal fluid of S. Typhi, male, mice BALB/c. Mice were divided into three groups comprised of 10 mice each. All mice in groups A and B were intraperitoneally inoculated with S. Typhi strain Thy1 in study day 0. Group A was treated with antibiotic Levofloxacine, on study day 4th. Another study group, group B, was used as a placebo and received aquades on study day 4th. While group C as a control was not inoculated with S. Typhi. Blood samples from three groups for the calculation of serum Il-6, TNF-α, and VDR were collected. This examination was taken four times; at baseline, 4th day, 10th day, and 30th day. For the calculation of bacterial colony, peritoneal fluid retrieval was collected three times, which is on 4th day, 10th day, and 30th day. Results: A repeated measure ANOVA in group A (antibiotic) and group B (placebo) group showed that mean IL-6, TNF-α, and VDR level differed statistically significant between times (p-value 0.000). There was a strong negative correlation between bacterial colony count and VDR level, which was statistically significant in both groups (group A; r = -0.875, p-value = 0.000 vs group B; r = -0.470, p-value = 0.002). IL-6 and TNF-α didn't give significant statistical correlation with bacterial colony count. Conclusion: VDR, IL-6, and TNF-α play an important role in killing bacteria. From the results of this study, IL-6 level is related to the number of bacterial colonies, the lower the IL-6 level, the less the number of bacterial colonies. Similarly, TNF-α levels have a positive correlation with the number of bacterial colonies. While VDR levels are also related to the number of bacterial colonies, the higher the VDR level, the lower the number of bacterial colonies.

Intestinal responses to 1,25 dihydroxyvitamin D are not improved by higher intestinal VDR levels resulting from intestine-specific transgenic expression of VDR in mice

Intestinal calcium (Ca) absorption depends upon vitamin D signaling through the vitamin D receptor (VDR) in the proximal and distal intestine while lower VDR content causes intestinal resistance to 1,25 dihydroxyvitamin D (1,25(OH)2 D) action. We tested whether intestinal responsiveness to 1,25(OH)2 D is increased in mice with higher than normal VDR levels resulting from transgenic VDR expression in the whole intestine (villin promoter-human VDR transgene, HV2). Wild type (WT) and HV2 mice were treated with 0, 0.15, or 0.3 ng 1,25(OH)2 D/g body weight (BW) (n = 6/dose) for 6 h. 1,25(OH)2 D significantly induced Cyp24a1, Trpv6, and S100 g mRNA in duodenum (Dd) of WT mice but induction was not higher in HV2 mice. We next tested whether higher intestinal VDR could protect mice from the consequences of low dietary Ca intake. WT and HV2 mice were fed diets with 0.125, 0.25, 0.5 (reference), or 1% Ca from weaning to 3 months of age (n = 9/diet/genotype). Dietary Ca restriction caused a dose dependent increase in serum 1,25(OH)2 D, Dd TRPV6, and Dd S100 g mRNA in WT mice and the effect was greater in HV2 mice. While Ca absorption was increased by low Ca intake, there was no difference in Ca absorption between HV2 and WT mice. Similarly, while bone density and microstructure were reduced by low Ca intake in WT mice, high intestinal VDR in HV2 mice did not protect bone in mice fed low Ca diets. Thus, while intestinal VDR and vitamin D signaling are essential for normal Ca metabolism during growth, our data demonstrate that higher than normal intestinal VDR levels do not improve the intestinal response to either 1,25(OH)2 D injection or to elevated 1,25(OH)2 D levels resulting from the physiologic adaptation to low Ca diets.

25(OH) D3 alleviate liver NK cytotoxicity in acute but not in chronic fibrosis model of BALB/c mice due to modulations in vitamin D receptor

BackgroundLow 25-Hydroxy-vitamin-D; “25(OH)-D3” serum and vitamin D receptor (VDR) levels were recently correlated to advanced fibrosis. However, VDR mechanism in liver fibrosis modulations is not well understood. In this study, we aimed to evaluate changes in liver NK cells cytotoxicity due to modulations in VDR in CCl4 fibrosis model following 25(OH) D3 injections.MethodsCarbon-tetrachloride (CCl4) hepatic-fibrosis was induced in BALB/c mice for 1 and 4 weeks as an acute and chronic fibrosis model, respectively. Along 1th to 4th weeks, vitamin D were i.p injected/2x week. Liver were assessed histologically and for proteins quantification for VDR and αSMA expressions. In vitro, potential killing of NK cells were evaluated following co-culture with primary-hepatic-stellate-cells (pHSCs) obtained from BALB/c WT-mice.ResultsSystemic inflammation and hepatic-fibrosis increased along 4 weeks of CCl4 as indicated by serum ALT and αSMA expressions (P < 0.02) as well as histological assessments, respectively. These results were associated with increased NK1.1 activations and hypercalcemia. While vitamin D administrations delayed fibrosis of early stages, vitamin D worsen hepatic-fibrosis of late stages of CCl4. In week 4, no further activations of NK cells were seen following vitamin D injections and were associated with down-expressions of VDR (1.7 Fold, P < 0.004) indicating the inability of vitamin D to ameliorate hepatic fibrosis. In vitro, NK cells from the chronic model of CCl4 did not affect pHSCs killing and fail to reduce fibrosis.ConclusionVitamin D alleviate liver NK cytotoxicity in acute but not in chronic fibrosis model due to modulations in vitamin D receptor and calcium. Hypercalcemia associated with late fibrosis may inhibited VDR levels, however, may not explain the profibrogenic effects of vitamin D.

Older Age Is Associated with Decreased Levels of VDR, CYP27B1, and CYP24A1 and Increased Levels of PTH in Human Parathyroid Glands.

Parathyroid glands contain the vitamin D receptor (VDR) and 25-hydroxyvitamin D-1α-hydroxylase (CYP27B1) and 24-hydroxylase (CYP24A1), which catalyze the production and degradation of 1,25-dihydroxyvitamin D [1,25(OH)2D], respectively. Previous studies have shown that the serum level of intact parathyroid hormone (iPTH) increases with age. We hypothesized that the expression of CYP27B1 or VDR in parathyroid glands decreases with age, which might account for the increased serum levels of iPTH due to decreased suppression of parathyroid hormone (PTH) secretion by 1,25(OH)2D in older people. To test this hypothesis, we examined relative expression levels of VDR, CYP27B1, CYP24A1, and PTH in specimens from parathyroid glands unintentionally removed during thyroidectomy for 70 patients varying in age from 10 to 70 years. The results showed that there was an inverse correlation between age and VDR, CYP27B1, and CYP24A1 expression (p < 0.05). A significant positive correlation between PTH expression levels and age was also observed (p < 0.05). These data indicate that older age is associated with decreased levels of VDR, CYP27B1, and CYP24A1 and increased levels of PTH in human parathyroid glands.

Myeloid vitamin D receptor influences cell proliferation in small intestine

The vitamin D receptor (VDR) is a ubiquitous nuclear receptor that acts as a transcription factor when vitamin D binds with VDR. Intestinal epithelial VDR has various physiological and anatomical benefits to intestine. Interactions between intestinal epithelial cells (IEC) and immune cells are critical for gut health. Cellular proliferation through Wnt/β‐catenin signaling is a result of immune and IEC crosstalk. Wnt proteins from macrophages bind to intestinal epithelial cells and activate the Wnt/β‐catenin pathway. This pathway is critical for cell proliferation which enables food and water absorption in the small intestine. However, the importance of myeloid VDR in regulating the Wnt/β‐catenin pathway in epithelial cells is not fully understood. The objective of this study is to assess how the presence of myeloid VDR in the intestinal epithelial cells influences cellular proliferation through the Wnt/β‐catenin pathway. We hypothesize that the low level of myeloid VDR will reduce expression of Wnt/β‐catenin signaling downstream and alleviate cell proliferation in the small intestine. This experiment utilized selective deletion of myeloid VDR in an ex‐vivo and in‐vivo set‐up. For the ex‐vivo, control mice (VDRLoxP) were crossed with lysozyme (M) ‐cre mice to create specific knockout of myeloid VDR (VDRrLyz) mice. Twelve mice (6 VDRLoxP mice and 6 VDRrLyz) were sacrificed and mucosal scrapings from the ileum (small intestine) were collected for westerns. For cell culture, small intestine organoids derived from the intestinal stem cells were cultured alone or co‐cultured with macrophages (VDR+/+ or VDR−/−). After 3 days, the organoids and organoid‐macrophage co‐cultures were collected for western blots. Western blots were used to measure and compare expression of Wnt/β‐catenin signaling proteins. The VDR−/− organoid macrophage co‐culture showed significantly decreased expression of β‐catenin and PCNA (a cell proliferation marker), compared to the VDR+/+ organoid macrophage co‐culture. Our results suggest that myeloid VDR influences the Wnt/β‐catenin signaling pathway. We present a novel role of myeloid VDR signaling in mediating immune/epithelial cell cross talk in intestine.

A simple and sensitive method to detect vitamin D receptor expression in various disease models using stool samples

Vitamin D receptor (VDR) executes the main biological functions of its ligand vitamin D. VDR/vitamin D plays critical roles in regulating host immunity, maintaining barrier functions, and shaping gut microbiome. Reduction of intestinal VDR has been reported in various diseases, including inflammatory diseases and colon cancer. However, it is always challenging to get biopsies to test the pathologic changes of VDR in intestine. In the current study, we reported a simple and sensitive quantitative PCR (qPCR) method to detect reduction of intestinal VDR using fecal samples. We validated this method in several experimental models, such as colitis, bacterial infection, and aging. We further correlated the qPCR data of VDR with the protein level of VDR in colon or serum 25 (OH)D3 in mice with different VDR status (VDR+/+, VDR+/-, and VDR−/−). Our data indicate that the qPCR method to test VDR using fecal samples could detect the expression level of intestinal VDR in various diseases. Our study highlights the feasibility, sensitivity, and simplicity of a molecular method to study the status of VDR as a biomarker.

Characterization of VDR and CYP27B1 expression in the endometrium during the menstrual cycle before embryo transfer: implications for endometrial receptivity

BackgroundMolecular analyses of vitamin D in a typical cycling endometrium has received minimal research attention in the reproductive field. This study was designed to assess how expression of the endometrial vitamin D receptor (VDR) and CYP27B1, a vitamin D metabolizing enzyme, change during the menstrual cycle in women of reproductive age. In addition, this study explores the association between expression of vitamin D-VDR system and endometrial receptivity during the implantation window.MethodsSixteen patients underwent standardized in vitro fertilization (IVF) treatment and freeze-all techniques. Before embryo transfer, total serum 25(OH) D levels were determined through blood samples and VDR, CYP27B1, HOXA10, and CYP19 expression were determined through endometrial samples. Endometrial receptivity was also assessed using an electron microscope.ResultsWe found that VDR protein expression was significantly lower throughout the endometrial secretory phase compared to the proliferative phase, while CYP27B1 expression remained constant during the menstrual cycle. During the implantation window, ultrastructural evaluation showed that higher serum vitamin D levels were associated with more mature pinopodes; VDR and HOXA10 protein expression were substantially elevated in pregnant women compared to non-pregnant women; and VDR protein levels were positively correlated with HOXA10 levels. In addition, serum vitamin D levels were positively correlated with VDR and HOXA10 protein levels in the endometrium.ConclusionsWomen with increased VDR expression in the endometrium, especially during the implantation window of the menstrual cycle, were significantly more likely to be pregnant than women with decreased expression. Our results support the hypothesis that the Vitamin D-VDR system performs a role during the development of endometrial receptivity.

Vitamin D Receptor Overexpression in β-Cells Ameliorates Diabetes in Mice.

Vitamin D deficiency has been associated with increased incidence of diabetes, both in humans and in animal models. In addition, an association between vitamin D receptor (VDR) gene polymorphisms and diabetes has also been described. However, the involvement of VDR in the development of diabetes, specifically in pancreatic β-cells, has not been elucidated yet. Here, we aimed to study the role of VDR in β-cells in the pathophysiology of diabetes. Our results indicate that Vdr expression was modulated by glucose in healthy islets and decreased in islets from both type 1 diabetes and type 2 diabetes mouse models. In addition, transgenic mice overexpressing VDR in β-cells were protected against streptozotocin-induced diabetes and presented a preserved β-cell mass and a reduction in islet inflammation. Altogether, these results suggest that sustained VDR levels in β-cells may preserve β-cell mass and β-cell function and protect against diabetes.

1,25-hydroxyvitamin D3 decreases endoplasmic reticulum stress-induced inflammatory response in mammary epithelial cells.

Recent studies indicated that intramammary administration of active vitamin D3 hormone (1,25D3) inhibits the inflammatory process associated with mastitis. We hypothesized that attenuation of endoplasmic reticulum (ER) stress by 1,25D3 in mammary epithelial cells (MECs) is an important cellular mechanism contributing to this beneficial effect of intramammary treatment with 1,25D3. To test this hypothesis, the effect of 1,25D3 was studied on induction of ER stress in a transformed human MEC line, MCF-7 cells. Treatment with two different ER stress inducers, thapsigargin (TG) and tunicamycin (TM), caused a dose-dependent induction of ER stress as evident from up-regulation of protein kinase RNA-like ER kinase (PERK), heat shock protein family A (Hsp70) member 5 (HSPA5), activating transcription factor (ATF4), ATF6, DNA damage inducible transcript 3 (DDIT3) and spliced X-box binding protein 1 (sXBP1) and impaired cell viability and decreased expression of vitamin D receptor (VDR) in MCF-7 cells (P < 0.05). Treatment with 1,25D3 (100 nM) inhibited TG (10 nM)- and TM (1 μg/mL)-induced mRNA and/or protein levels of ATF4, ATF6, DDIT3 and HSPA5 in MCF-7 cells (P < 0.05). In addition, 1,25D3 (100 nM) antagonized the effect of TG (10 nM) and TM (1 μg/mL) on mRNA and protein levels of VDR and mRNA levels of genes involved in production and degradation of 1,25D3 in MCF-7 cells (P < 0.05). Moreover, 1,25D3 (100 nM) inhibited nuclear factor-κB (NF-κB) activation in response to TM (10 nM) and TG (1 μg/mL) in MCF-7 cells. In conclusion, the present findings show that 1,25D3 is effective in attenuating ER stress and the NF-κB-driven inflammatory response in MCF-7 cells. This indicates that attenuation of ER stress by 1,25D3 in MECs may contribute to the recently observed inhibitory effect of intramammary treatment of dairy cows with 1,25D3 on the inflammatory process associated with mastitis.

Effect of Vitamin D on Relapse-Free Survival in a Subgroup of Patients with p53 Protein-Positive Digestive Tract Cancer: A Post Hoc Analysis of the AMATERASU Trial.

The AMATERASU randomized trial of vitamin D3 supplementation (2,000 IU/day; UMIN000001977) showed the potential benefit of vitamin D in a subgroup of patients with digestive tract cancer. By conducting post hoc analyses of this trial, we further explored whether subgroups stratified by expression levels of p53, vitamin D receptor (VDR), and Ki-67 modify the effect of vitamin D supplementation. The primary outcome was relapse-free survival (RFS). On IHC using pathologic specimens, the degree of p53 protein expression parallel with TP53 missense mutations was classified as p53 positive (>10%) and p53 negative (≤10%). In addition, VDR and Ki-67 expression levels were divided into quartiles. The p53 status of 372 patients' pathologic specimens was evaluated. In a subgroup of patients with p53-positive cancer (n = 226), 5-year RFS was 79% in the vitamin D group, which was significantly higher than the 57% in the placebo group (HR, 0.52; 95% confidence interval, 0.31-0.88; P = 0.02). In the subgroup of patients with p53-negative cancer, 5-year RFS in the vitamin D group versus placebo group was 72% versus 84% (not significantly different), respectively. Effect modification by p53 positivity was significant (P interaction = 0.02). However, no significant effect modification by either VDR or Ki-67 was observed. These results generate a hypothesis that vitamin D supplementation may improve RFS in patients with p53-positive digestive tract cancer. The results are still preliminary, but potentially important, because TP53 is the most frequently mutated gene across cancers at all sites.

Serum vitamin D receptor (VDR) levels as a potential diagnostic marker for colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of mortality and morbidity worldwide, and there has been a significant increase in the incidence of CRC in recent decades. Therefore, there is an urgent need to identify blood biomarkers that can be used for early diagnosis. It is not yet clear whether the level of vitamin D and its receptor, vitamin D receptor (VDR), in the blood are helpful factors in the diagnosis of CRC. Therefore, the study focuses on determining the VDR serum level’s contribution and other chemical parameters to the risk of CRC. A total of 189 Saudi participants (66 CRC patients and 123 control patients) aged 20–80 years old were enrolled in this case-control study. A serum sample was collected from each participant, and the levels of VDR and other bone profile tests were determined using ELISA or chemiluminescent assays. P values < 0.05 were considered statistically significant. The results showed a highly significant reduction in the levels of total vitamin D (P < 0.0001), VDR (P < 0.0001), vitamin D3 (P < 0.05), and calcium (P < 0.0001) in the serum of CRC patients compared to the controls. However, the alkaline phosphatase level was higher in CRC patients compared to the controls (P < 0.0001). None of the blood markers showed a significant correlation to the progression of CRC (P > 0.05). More investigation is needed to elucidate different physiological processes that can be affected by these blood biomarkers, therefore changing the carcinogenesis of CRC.

Propionate promotes vitamin D receptor expression via yes-associated protein in rats with short bowel syndrome

Vitamin D deficiency and refractory osteoporosis are common complications in patients with short bowel syndrome (SBS). The symptom of bone loss is not effectively alleviated, even after the oral administration of vitamin D in SBS patients who had been weaned off parenteral nutrition. In this study, we aimed to investigate the effect of propionate on the expression of the vitamin D receptor (VDR) in the small intestine of rats with SBS. Firstly, IEC-6 (intestinal epithelioid cell line No. 6) cells were incubated in vitro with 1 mM sodium propionate for 24 h. This resulted in a significant increase in the expression of VDR and yes-associated protein (YAP) compared with that in the control group. Transfection of IEC-6 cells with YAP siRNA significantly down-regulated the expression of VDR. By contrast, after incubating IEC-6 cells with lysophosphatidic acid, an agonist of YAP, upregulation of VDR and YAP was observed. Next, we investigated whether this effect occurs in vivo. Five-week-old male Sprague-Dawley rats underwent 80% small bowel resection to establish an SBS model. Rats treated with 1% w/v sodium propionate had high levels of VDR and YAP expression in the intestine and intestinal adaptation was clearly observed compared to the control group. However, these effects were blocked by intraperitoneal injection of verteporfin. Thus, this study showed that propionate promoted VDR expression in the intestine via the activity of YAP, both in vitro and in vivo. Moreover, propionate was shown to play an active role in postoperative intestinal adaptation in SBS rats.