Effects Of Calcitriol Research Articles

Vitamin D receptor activation is a feasible therapeutic target to impair adrenocortical tumorigenesis

ObjectiveTo evaluate the therapeutic potential of vitamin D receptor (VDR) signaling in adrenocortical carcinoma (ACC) cells. MethodsWe evaluated VDR's methylation pattern in H295R ACC cells, and investigated the effects of calcitriol and seocalcitol treatments on adrenocortical tumorigenesis. ResultsVDR was hypermethylated and underexpressed in basal H295R cells. Treatments with calcitriol and seocalcitol restored VDR signaling, resulted in antiproliferative effects, and impaired Wnt/B-catenin signaling. RNAseq of treated cells demonstrated VDR activation on steroid hormones biosynthesis and Rap1 signaling, among others. In vivo, seocalcitol constrained the growth of H295R xenografts and reduced autonomous tumor steroid secretion without hypercalcemia-associated side effects. ConclusionsH295R cells present VDR hypermethylation, which can be responsible for its underexpression and signaling inactivation under basal conditions. VDR signaling promoted antiproliferative effects in vitro and in vivo, suggesting that it may be a potential therapeutic target for ACC and a valuable tool for patient's clinical management.

Anti-Inflammatory Effects of 1,25(OH)2D/Calcitriol in T Cell Immunity: Does Sex Make a Difference?

Hypovitaminosis D is involved in various inflammatory, infectious and autoimmune diseases such as rheumatoid arthritis and multiple sclerosis. Moreover, the active form of vitamin D, calcitriol, has been shown to modulate the immune response, playing an anti-inflammatory effect. However little is known about the mechanisms underlying this anti-inflammatory effect and the potential sex differences of calcitriol immune regulation. Hence, the aim of this study was to investigate whether calcitriol could act differently in modulating T cell immunity of age-matched male and female healthy donors. We analyzed the effects of calcitriol in T lymphocytes from healthy women and men on the expression levels of the vitamin D receptor (VDR) and pro- and anti-inflammatory cytokine production. We showed that a treatment with calcitriol induced a significant increase in the VDR expression levels of activated T lymphocytes from male and female healthy subjects. Moreover, we found that calcitriol significantly reduced the expression level of pro-inflammatory cytokines IL-17, INF-γ and TNF-α in the T lymphocytes of both sexes. Notably, we observed that calcitriol induced a significant increase in the expression level of anti-inflammatory cytokine IL-10 only in the T lymphocytes from female healthy donors. In conclusion, our study provides new insights regarding the sex-specific anti-inflammatory role of calcitriol in T cell immunity.

Effects of calcitriol on the cell cycle of rhabdomyosarcoma cells

Rhabdomyosarcoma (RMS) is a type of cancer of skeletal muscle. Calcitriol is the active form of vitamin D3, also recognised as a steroid hormone called 1α, 25-dihydroxy vitamin D3 (1,25D). We previously reported that 1,25D promoted cell proliferation and differentiation in non-cancerous skeletal muscle cells C2C12. The aim of this work is to evaluate some of the events triggered by 1,25D in RD cells, a human RMS cell line. In this work we reported that RD cells expressed vitamin D receptor (VDR) and treatment with 1,25D reduced VDR expression at 72 h. At the same time an acute decrease in viable cells as well as in cells in S-phase of cell cycle was also observed. Furthermore, up-regulation of p15INK4b was accompanied in a timely manner by down-regulation of cyclin D3, p21Waf1/Cip1 and myogenin protein levels. Simultaneously, 1,25D induced early apoptosis markers such as cyclin D1 and CDK4, and the disruption of the mitochondrial network together with a redistribution of mitochondria around the nucleus. Finally, 1,25D induced changes in the plasma membrane of RD cells associated with early and late apoptosis at 72 h, as determined by flow cytometry. Taken together, these results determine that treatment with 1,25D for 72 h triggers apoptosis in RD cells.

Combination of Calcitriol and Zoledronic Acid on PINP and β-CTX in Postoperative Patients with Diabetic Osteoporosis: A Randomized Controlled Trial

Objective To explore the effect of calcitriol combined with zoledronic acid in posterior cruciate ligament tibial avulsion fractures of the knee joint in patients with diabetic osteoporosis. Methods Between January 2020 and January 2022, 60 patients with diabetic osteoporosis treated in our hospital were included. All patients underwent knee joint posterior cruciate ligament tibial avulsion fractures, and they were randomized (1 : 1) into the observation group (calcitriol combined with zoledronic acid) and control group (calcitriol). The two groups were compared with respect to the improvement of bone mineral density and bone metabolism indexes, the pain degree (VAS) and knee joint function (Lysholm), and the incidence of refracture. Results Both groups showed an increasing bone mineral density after treatment, and significant increase was observed in the observation group vs. control group (all p < 0.05). After treatment, VAS scores decreased in the two groups, and Lysholm scores increased compared to the corresponding values before treatment (all p < 0.05), with more notable changes in the observation group versus control group (all p < 0.05). The observation group had fewer cases of refractures than the control group (2 cases vs. 8 cases) (p < 0.05). Conclusion Calcitriol combined with zoledronic acid used in patients with diabetic osteoporosis after the posterior cruciate ligament tibial attachment avulsion fracture of the knee joint yields a promising result in enhancing bone mineral density and bone metabolism indicators, relieving pain, improving knee joint function, and reducing the risk of refracture.

Intravenous calcitriol treatment benefits the homeostasis of CD4+ T cells and attenuates kidney injury in obese mice complicated with polymicrobial sepsis

ObjectivesSepsis is a lethal clinical condition with dysregulated cluster of differentiation (CD) 4+ T cells that leads to inflammation and multiorgan injury. Low vitamin D levels are commonly seen in patients with sepsis. Obesity is a state with oxidative stress and chronic inflammation. Both obesity and low vitamin D levels are associated with adverse outcomes in patients with sepsis. This study investigated the effects of calcitriol on CD4+ T-cell polarization and kidney injury during sepsis. MethodsMice were fed a high-fat diet to induce obesity. One group of obese mice served as the control group and in the other two groups (SS and SD) were performed cecal ligation and puncture (CLP) to induce sepsis. Mice in the SS group were injected with saline and those in the SD group with calcitriol 1 h after CLP via tail vein. Mice with sepsis were euthanized at 12 h and 24 h after CLP, respectively. ResultsSepsis led to a decrease in circulating CD4+ T-cell percentage, and T helper (Th) 2, Th17, and regulatory T (Treg) cell percentages were upregulated. Compared with the SS group, the SD group maintained blood CD4+ T-cell levels, and were reduced the Th2 and Th17 percentages as well as the Th17:Treg ratio. Also, plasma levels of cathelicidin increased, but inflammatory chemokines and kidney injury markers were reduced. Higher arginase-1 and lower inducible nitric oxide synthase expressions in the SD group indicated M1 macrophage polarized toward the M2 type. ConclusionsThese findings suggest that intravenous calcitriol administration after sepsis modulates the homeostasis of CD4+ T-cell subpopulations associated with alleviating sepsis-induced kidney injury in obese mice.

Novel Insights into the Cardioprotective Effects of Calcitriol in Myocardial Infarction.

Background: Increasing evidence indicates that vitamin D deficiency negatively affects the cardiovascular system. Here we studied the therapeutic effects of calcitriol in myocardial infarction (MI) and investigated its underlying mechanisms. Methods: A MI model of Kun-ming mice induced by left anterior descending coronary artery ligation was utilized to study the potential therapeutic effects of calcitriol on MI. AC16 human cardiomyocyte-like cells treated with TNF-α were used for exploring the mechanisms that underlie the cardioprotective effects of calcitriol. Results: We observed that calcitriol reversed adverse cardiovascular function and cardiac remodeling in post-MI mice. Mechanistically, calcitriol suppressed MI-induced cardiac inflammation, ameliorated cardiomyocyte death, and promoted cardiomyocyte proliferation. Specifically, calcitriol exerted these cellular effects by upregulating Vitamin D receptor (VDR). Increased VDR directly interacted with p65 and retained p65 in cytoplasm, thereby dampening NF-κB signaling and suppressing inflammation. Moreover, up-regulated VDR was translocated into nuclei where it directly bound to IL-10 gene promoters to activate IL-10 gene transcription, further inhibiting inflammation. Conclusion: We provide new insights into the cellular and molecular mechanisms underlying the cardioprotective effects of calcitriol, and we present comprehensive evidence to support the preventive and therapeutic effects of calcitriol on MI.

Calcitriol Inhibits Proliferation and Potentially Induces Apoptosis in B16-F10 Cells.

BackgroundMelanoma is one of the most aggressive types of cancer and it has shown a remarkable surge in incidence during the last 50 years. Melanoma has been projected to be continuously rising in the future. Therapy for advanced-type melanoma is still a challenge due to the low response rate and poor 10-year survival. Interestingly, several epidemiological and preclinical studies had reported that vitamin D deficiency was associated with disease progression in several cancer types. In vivo and in vitro studies revealed anti-proliferative, anti-angiogenic, apoptosis, and differentiation induction effects of calcitriol in various cancers. However, information on the effects of calcitriol (1,25(OH)2D3) on melanoma is still limited, and its mechanism remains unclear.Material/MethodsIn the present study, by utilizing B16–F10 cells, which is a melanoma cell line, we explored the anti-proliferative effect of calcitriol using cell viability assay, near-infrared imaging, expression of apoptosis-related genes using real-time polymerase chain reactions (PCR), and the expression of apoptosis proteins levels using western blot. In addition, we also assessed calcitriol uptake by B16–F10 cells using high-performance liquid chromatography (HPLC).ResultsWe found that calcitriol inhibits melanoma cell proliferation with an IC50 of 93.88 ppm (0.24 μM), as shown by cell viability assay. Additionally, we showed that B16–F10 cells are capable of calcitriol uptake, with a peak uptake time at 60 min after administration. Calcitriol was also able to induce apoptosis-related proteins such as caspase-3, caspase 8, and caspase-9. These effects of calcitriol reflect its potential utility as a potent adjuvant therapy for melanoma.ConclusionsCalcitriol inhibits cell proliferation and induces apoptosis in B16–F10 cells.

Effects of calcitriol upon TGF-ΒS and their receptors in trophoblast cells

Effects of calcitriol upon TGF-ΒS and their receptors in trophoblast cells

Regulation of 1 and 24 hydroxylation of vitamin D metabolites in the proximal tubule.

Calcium and phosphate are critical for numerous physiological processes. Consequently, the plasma concentration of these ions are tightly regulated. Calcitriol, the active form of vitamin D, is a positive modulator of mineralization as well as calcium and phosphate metabolism. The molecular and physiological effects of calcitriol are well documented. Calcitriol increases blood calcium and phosphate levels by increasing absorption from the intestine, and resorption of bone. Calcitriol synthesis is a multistep process. A precursor is first made via skin exposure to UV, it is then 25-hydroxylated in the liver to form 25-hydroxyitamin D. The next hydroxylation step occurs in the renal proximal tubule via the 1-αhydroxylase enzyme (encoded by CYP27B1) thereby generating 1,25-dihydroxyvitamin D, that is, calcitriol. At the same site, the 25-hydroxyvitamin D 24-hydroxlase enzyme encoded by CYP24A1 can hydroxylate 25-hydroxyvitamin D or calcitriol to deactivate the hormone. Plasma calcitriol levels are primarily determined by the regulated expression of CYP27B1 and CYP24A1. This occurs in response to parathyroid hormone (increases CYP27B1), calcitriol itself (decreases CYP27B1 and increases CYP24A1), calcitonin (increases or decreases CYP24A1 and increases CYP27B1), FGF23 (decreases CYP27B1 and increases CYP24A1) and potentially plasma calcium and phosphate levels themselves (mixed effects). Herein, we review the regulation of CYP27B1 and CYP24A1 transcription in response to the action of classic phophocalciotropic hormones and explore the possibility of direct regulation by plasma calcium.

P234 The effect of calcitriol on the expression of interferon signature genes in dendritic cells and macrophages in systemic lupus erythematosus

Abstract Background/Aims A number of studies have demonstrated the inverse association between vitamin D and (i) disease activity and (ii) interferon (IFN) signature gene expression in systemic lupus erythematosus (SLE). The aim of the study was to establish the effect of calcitriol supplementation to cultured macrophages and dendritic cells (DC) from a SLE patient and control, on the expression of 12 IFN signature genes, interferon regulatory factor (IRF)7 and IRF8. Methods Blood samples were collected from a 41-year-old female SLE patient who fulfilled the SLICC classification criteria for SLE and from a 36-year-old healthy female control after obtaining informed consent. Both patients had a serum 25-hydroxyvitamin D level of 25ng/ml. Peripheral blood mononuclear cells (PBMC) were isolated by using histopaque®-1077. CD83 and CD14 expression was measured by flow cytometry and cell count and viability were assessed. The PBMC suspension was cultured in 6-well plates using: (i) ImmunoCultTM DC culture kit (following kit protocol) for DC differentiation, (ii) culture medium for macrophage differentiation containing RPMI 1640 Medium, DMEM, fetal bovine serum and LPS. Following 7 days of incubation, differentiation of cells was confirmed using microscopy and flow cytometry to measure CD83 and CD14 expression. Calcitriol at a concentration of 20nM was added to half of the wells of each sample category. Following 24 and 48 hours, RNA extraction was carried out on treated and untreated samples. QuantiGene Plex technology was used to measure the expression of 12 IFN signature genes, IRF7, IRF8 and four housekeeping genes in the extracted RNA. The normalised median florescence intensity for the 12 IFN signature genes was used to calculate the IFN score. Results A significantly lower IFN score was noted at 24 hours in SLE patient dendritic cell and macrophage cell cultures and in control macrophage cell cultures treated with calcitriol when compared with respective untreated samples (p = 0.014, p = 0.034, p = 0.031 respectively). On comparing IRF8 expression in treated and untreated cell cultures, a significantly lower IRF8 expression was noted in treated macrophage cell cultures obtained from both SLE patient and control (p = 0.034, p = 0.041). No difference in IRF7 expression was noted in treated and untreated cultures for all samples. Conclusion The suppression of the interferon signature genes in dendritic cell and macrophage cell cultures with vitamin D was confirmed in the in vitro experiment carried out. In this experiment a decrease in the expression of IRF8 (known to have a VDR binding site) was also observed in macrophage cultures from both SLE patient and control. Disclosure R. Magro: None. E. Seria: None. G. Grech: None. A.A. Borg: None. C. Scerri: None.

Calcitriol ameliorates renal injury with high-salt diet-induced hypertension by upregulating GLIS2 expression and AMPK/mTOR-regulated autophagy.

The goal of the present study was to investigate the protective effect of calcitriol on high-salt diet-induced hypertension. The hypertension rat model was established by a long-term high-salt diet (8% NaCl). Rats were treated with calcitriol, losartan, or their combination. Histological staining was used to confirm renal pathology. Global transcriptome analysis of renal tissues was performed, and the mechanism of the therapeutic effect of calcitriol was analysed by functional annotation and pathway analysis of the differentially expressed genes (DEGs) as well as by Western blotting analysis. The core genes for potential therapeutic regulation were identified through the coexpression gene network. For in vitro HK-2 cell experiments, small interfering RNA (siRNA) was used to knockdown key a transcription factor (TF) Glis2 to validate the therapeutic target of calcitriol. MAPK1 and CXCL12 expression was downregulated and the apoptosis pathway was significantly enriched by calcitriol treatment. The western blotting results showed that calcitriol treatment increased AMPK phosphorylation and decreased downstream mTOR phosphorylation, which was accompanied by a decrease in autophagy protein p62 expression and an increase in LC3-II/I expression. GLIS2 was identified as a specific therapeutic target for calcitriol. GLIS2 expression was upregulated by calcitriol and confirmed by HK-2 cells in vitro. Our omics data show that calcitriol can alleviate oxidative stress and fibrosis. Moreover, calcitriol can regulate the CXCL12/ERK1/2 cascade to inhibit the inflammatory response and renal cell apoptosis and induce renal autophagy through the AMPK/mTOR pathway. Our study partially elucidate the pathogenesis and treatment mechanism underlying hypertension, and provide new insights into the treatment of hypertension.

Vitamin D and Hypoxia: Points of Interplay in Cancer.

Simple SummaryVitamin D, conventionally considered a nutrient, is a potent hormone regulating many physiological functions. In addition, many studies point to the anticancer activities of calcitriol. However, cancer cells use mechanisms that negate the beneficial effects of calcitriol. Many of these mechanisms control or are controlled by the Hypoxia Inducible transcription Factors (HIFs) that are overexpressed in human cancers due to the development of hypoxia inside the tumors. This review discusses the crosstalk between calcitriol and HIF signaling in order to better understand their relationship to cancer, its prevention, and treatment.Vitamin D is a hormone that, through its action, elicits a broad spectrum of physiological responses ranging from classic to nonclassical actions such as bone morphogenesis and immune function. In parallel, many studies describe the antiproliferative, proapoptotic, antiangiogenic effects of calcitriol (the active hormonal form) that contribute to its anticancer activity. Additionally, epidemiological data signify the inverse correlation between vitamin D levels and cancer risk. On the contrary, tumors possess several adaptive mechanisms that enable them to evade the anticancer effects of calcitriol. Such maladaptive processes are often a characteristic of the cancer microenvironment, which in solid tumors is frequently hypoxic and elicits the overexpression of Hypoxia-Inducible Factors (HIFs). HIF-mediated signaling not only contributes to cancer cell survival and proliferation but also confers resistance to anticancer agents. Taking into consideration that calcitriol intertwines with signaling events elicited by the hypoxic status cells, this review examines their interplay in cellular signaling to give the opportunity to better understand their relationship in cancer development and their prospect for the treatment of cancer.

Rapid Nontranscriptional Effects of Calcifediol and Calcitriol.

Classically, a secosteroid hormone, vitamin D, has been implicated in calcium and phosphate homeostasis and has been associated with the pathogenesis of rickets and osteomalacia in patients with severe nutritional vitamin D deficiency. The spectrum of known vitamin D-mediated effects has been expanded in recent years. However, the mechanisms of how exactly this hormone elicits its biological function are still not fully understood. The interaction of this metabolite with the vitamin D receptor (VDR) and, subsequently, with the vitamin D-responsive element in the region of specific target genes leading to the transcription of genes whose protein products are involved in the traditional function of calcitriol (known as genomic actions). Moreover, in addition to these transcription-dependent mechanisms, it has been recognized that the biologically active form of vitamin D3, as well as its immediate precursor metabolite, calcifediol, initiate rapid, non-genomic actions through the membrane receptors that are bound as described for other steroid hormones. So far, among the best candidates responsible for mediating rapid membrane response to vitamin D metabolites are membrane-associated VDR (VDRm) and protein disulfide isomerase family A member 3 (Pdia3). The purpose of this paper is to provide an overview of the rapid, non-genomic effects of calcifediol and calcitriol, whose elucidation could improve the understanding of the vitamin D3 endocrine system. This will contribute to a better recognition of the physiological acute functions of vitamin D3, and it could lead to the identification of novel therapeutic targets able to modulate these actions.

Calcitriol Pretreatment Attenuates Glutamate Neurotoxicity by Regulating NMDAR and CYP46A1 Gene Expression in Rats Subjected to Transient Middle Cerebral Artery Occlusion.

Although the neuroprotective effects of calcitriol have been demonstrated in a variety of neurological diseases, such as stroke, the precise molecular mechanism has yet to be determined. This study aimed to investigate the possible role of calcitriol as a neuroprotective agent via CYP46A1 and glutamate receptors in a middle cerebral artery occlusion (MCAO) animal model. The MCAO technique was performed on adult male Wistar rats to induce focal cerebral ischemia for 1 hour followed by 23 hours of reperfusion. Calcitriol was given for 7 days prior to stroke induction. Sensorimotor functional tests were done 24 hours after ischemia/reperfusion, and infarct volume was estimated by tetrazolium chloride staining of brain sections. Gene expression of NR2A, NR2B, NR3B, and CYP46A1 was evaluated by RT-PCR followed by western blotting for NR3B protein. Our data revealed that calcitriol pretreatment reduced lesion volume and improved ischemic neurobehavioral parameters. Calcitriol therapy altered the expression of glutamate receptor and CYP46A1 genes. A possible molecular mechanism of calcitriol to reduce the severity and complications of ischemia may be through alterations of glutamate receptor and CYP46A1 gene expression.

Enhanced in vitro tumoricidal effects of 5-Fluorouracil, thymoquinone, and active vitamin D3 triple therapy against colon cancer cells by attenuating the PI3K/AKT/mTOR pathway

AimsThis study measured the effects of 5-Fluorouracil (5-FU), calcitriol (VD3), and/or thymoquinone (TQ) single/dual/triple therapies on cell cycle progression, apoptosis, inhibition of the PI3K/AKT/mTOR pathway, and oxidative stress against colorectal cancer (CRC). Main methodsThe HT29, SW480 and SW620 cell lines were treated with 5-FU (50 μM), VD3 (25 μM), and TQ (75 μM), alone or combined for 12 h, prior to cell cycle/apoptosis analyses. Key findingsTQ monotherapy had greater anticancer effects to active VD3 or 5-FU, revealing higher expression of p21/p27/PTEN/BAX/Cyto-C/Casp-3 and increased levels of total glutathione, with inhibitions in CCND1/CCND3/BCL-2 and PI3K/AKT/mTOR molecules, alongside higher rates of apoptosis in HT29, SW480 and SW620 cells (P < 0.005 for all markers). Additionally, all combination protocols revealed enhanced modulations of the PI3K/PTEN/Akt/mTOR pathway, higher expression of p21/p27/PTEN/BAX/Cyto-C/Casp-3, and better anti-oxidant effects, than the monotherapies. Although TQ/5-FU and TQ/VD3 co-therapies were better relative to the VD3/5-FU regimen, the best tumoricidal effects were observed with triple therapy in the HT29 and SW480 cell lines, possibly by boosted attenuations of the PI3K/AKT/mTOR oncogenic pathway. In contrast, TQ single treatment was more effective than the triple therapy regimen in metastatic SW620 cells, suggesting that this protocol would be more useful therapeutically in late-stage CRC. SignificanceIn conclusion, this study is the first to demonstrated enhanced anti-tumorigenic effects for VD3, TQ, and 5-FU triple therapy against CRC cells and could represent the best strategy for treating early stages of malignancy, whereas TQ monotherapy could be a better approach for treating metastatic forms of the disease.

Effects of Ruxolitinib and Calcitriol Combination Treatment on Various Molecular Subtypes of Breast Cancer.

The anticancer effects of ruxolitinib and calcitriol against breast cancer were reported previously. However, the effect of ruxolitinib and calcitriol combination treatment on various molecular subtypes of breast cancer remains unexplored. In this study, we used MCF-7, SKBR3, and MDA-MB-468 cells to investigate the effect of ruxolitinib and calcitriol combination treatment on cell proliferation, apoptosis, cell cycle, and cell signaling markers, in vitro and in vivo. Our results revealed the synergistic anticancer effect of ruxolitinib and calcitriol combination treatment in SKBR3 and MDA-MB-468 cells, but not in MCF-7 cells in vitro, via cell proliferation inhibition, apoptosis induction, cell cycle arrest, and the alteration of cell signaling protein expression, including cell cycle-related (cyclin D1, CDK1, CDK4, p21, and p27), apoptosis-related (c-caspase and c-PARP), and cell proliferation-related (c-Myc, p-p53, and p-JAK2) proteins. Furthermore, in the MDA-MB-468 xenograft mouse model, we demonstrated the synergistic antitumor effect of ruxolitinib and calcitriol combination treatment, including the alteration of c-PARP, cyclin D1, and c-Myc expression, without significant drug toxicity. The combination exhibited a synergistic effect in HER2-enriched and triple-negative breast cancer subtypes. In conclusion, our results suggest different effects of the combination treatment of ruxolitinib and calcitriol depending on the molecular subtype of breast cancer.

Calcitriol supplementation attenuates cisplatin-induced behavioral and cognitive impairments through up-regulation of BDNF in male rats

Chemotherapy-induced cognitive impairment such as memory impairment and concentration problems are now extensively recognized as side effects of chemotherapy. These problems reduce the quality of life in patients. Therefore, the present study aims to examine the effects of calcitriol supplementation (100 ng/kg /day for five weeks) on cognitive impairment, behavioral deficits, and hippocampal brain-derived neurotrophic factor (BDNF) changes following cisplatin treatment (5 mg/kg/ once a week for five weeks). We also determined the impact of cisplatin and calcitriol administration on reaction time against the thermal stimulus and muscle strength. Our findings showed that cisplatin administration resulted in a significant increase in anxiety-like behaviors. Treatment of rats with cisplatin also impaired performance in the passive avoidance and novel object recognition tasks which are indicating cognitive deficits. Co-administration of calcitriol prevented the cisplatin-induced behavioral and cognitive impairments. Cisplatin exposure also resulted in enhanced reaction time to the thermal stimulus and decreased muscle ability. Besides, hippocampal BDNF levels were reduced in cisplatin-treated rats; however, calcitriol alleviated these effects of cisplatin and up-regulated BDNF mRNA in the hippocampus. In addition, calcitriol alone indicated a significant change in BDNF level compared to the control group. We conclude that increased hippocampal BDNF mediates the beneficial effects of calcitriol against neurotoxicity in cisplatin-exposed rats. However, further studies are required to explore the other mechanisms that mediate the beneficial effect of calcitriol

Calcitriol and enamel matrix derivative differentially regulated cemento-induction and mineralization in human periodontal ligament-derived cells.

Alveolar bone and cementum share many biological and developmental similarities. The mineralizing effect of calcitriol has been previously reported. Yet, its cemento-inductivity has not been confirmed. This study evaluated the potential cemento-inductivity effect of calcitriol and enamel matrix derivative (EMD) on human periodontal ligament-derived cells (hPDLCs). The hPDLCs obtained from extracted third molars or premolars were cultured with calcitriol, or EMD. Cementogenic gene expression was examined using real-time quantitative reverse transcription polymerase chain reaction. Expression analysis also included cementoblast-specific markers, cementum protein 1 (CEMP1), cementum attachment protein (CAP), and recently reported cementoblast-enriched genes, secreted frizzled related protein 1 (SFRP1), and Dickkopf-related protein 1 (DKK1). Mineralization capacities were evaluated by alkaline phosphatase (ALP) activity, Alizarin Red, and Von Kossa staining followed by scanning electron microscope imaging and element mapping. Among tested conditions, 10nM calcitriol enhanced most cementogenic gene expression, transforming growth factor-β1, bone morphogenetic proteins (BMP-2 and BMP-4), core-binding factor subunit alpha-1/Runt-related transcription factor 2, Type I collagen, ALP, bone sialoprotein, osteopontin), osteocalcin, CEMP1, and CAP, and Wnt signaling negative modulators, SFRP1 and DKK1, along with highest ALP activity and mineralization formation in hPDLCs. However, only moderate CEMP1 protein was observed. In contrast, EMD stimulated stronger CEMP1 and CAP protein, but presented weaker mineralization capacity, hinting at the possibility that strong stimulation of mineralization might dominate cemetogenic specific factors and vice versa. Calcitriol demonstrated not only great osteoinductivity, but also the potential to induce cementogenic gene expression by initiating hPDLC differentiation and promoting mineralization. Compared with calcitriol, EMD promoted cemento-inductivity in hPDLCs at a later time point via highly expressed CEMP1 and CAP protein, but with less mineralization. Thus, calcitriol and EMD could provide differential enhancement of cemento-induction and mineralization, likely acting at various differentiation stages.

Cytotoxic effects of calcitriol on osteosarcoma cells

Aim: It was aimed to examine the effect of calcitriol which has known anticancer activities, on the osteosarcoma cell line SAOS-2 cells [1,25(OH)2D3].Methods: SAOS-2 cells were grown in culture in conventional culture flasks in DMEM medium at 37°C and 5% CO2. When the cells were 70-80% confluent, morphological changes were examined under an inverted microscope. The cells were passaged into 96 microplates, and after passage, different concentrations of calcitriol was applied to the cells (0.1; 0.5; 1; 5; 10; 25 nM/ml) was done. After administration, cytotoxic effect and proliferation rates/cell proliferation were analyzed by MTT method.Results: The effect of calcitriol applied at different concentrations in cultured cells were 0.1, 1, 10, 25 nM/ml doses, in these groups proliferation was found to be statistically significantly reduced compared to the control group (p≤0.05).Conclusion: Our data imply that the antiproliferative effects of vitamin D applications can be benefited from in exosomal, combined and supportive treatments in osteosarcoma. Further trials are warranted to confirm and validate our findings.

Effect of Calcitriol on Bone Mineral Density and Bone Metabolism in Osteoporotic Rats

Effect of Calcitriol on Bone Mineral Density and Bone Metabolism in Osteoporotic Rats