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Asian Journal of Andrology 2018Signaling through the vitamin D receptor has been shown to be biologically active and important in a number of preclinical studies in prostate and other cancers.... (Review)
Review
Signaling through the vitamin D receptor has been shown to be biologically active and important in a number of preclinical studies in prostate and other cancers. Epidemiologic data also indicate that vitamin D signaling may be important in the cause and prognosis of prostate and other cancers. These data indicate that perturbation of vitamin D signaling may be a target for the prevention and treatment of prostate cancer. Large studies of vitamin D supplementation will be required to determine whether these observations can be translated into prevention strategies. This paper reviews the available data in the use of vitamin D compounds in the treatment of prostate cancer. Clinical data are limited which support the use of vitamin D compounds in the management of men with prostate cancer. However, clinical trials guided by existing preclinical data are limited.
Topics: Antineoplastic Combined Chemotherapy Protocols; Calcifediol; Calcitriol; Clinical Trials as Topic; Ergocalciferols; Humans; Male; Prostatic Neoplasms; Signal Transduction; Vitamin D; Vitamin D Deficiency
PubMed: 29667615
DOI: 10.4103/aja.aja_14_18 -
The American Journal of Clinical... Aug 2008Although researchers first identified the fat-soluble vitamin cholecalciferol almost a century ago and studies have now largely elucidated the transcriptional mechanism... (Review)
Review
Although researchers first identified the fat-soluble vitamin cholecalciferol almost a century ago and studies have now largely elucidated the transcriptional mechanism of action of its hormonal form, 1alpha,25-dihydroxyvitamin D(3) [1alpha,25(OH)(2)D(3)], we know surprisingly little about mechanisms of vitamin D toxicity. The lipophilic nature of vitamin D explains its adipose tissue distribution and its slow turnover in the body (half-life approximately 2 mo). Its main transported metabolite, 25-hydroxyvitamin D(3) [25(OH)D(3)], shows a half-life of approximately 15 d and circulates at a concentration of 25-200 nmol/L, whereas the hormone 1alpha,25(OH)(2)D(3) has a half-life of approximately 15 h. Animal experiments involving vitamin D(3) intoxication have established that 25(OH)D(3) can reach concentrations up to 2.5 mumol/L, at which it is accompanied by hypercalcemia and other pathological sequelae resulting from a high Ca/PO(4) product. The rise in 25(OH)D(3) is accompanied by elevations of its precursor, vitamin D(3), as well as by rises in many of its dihydroxy- metabolites [24,25(OH)(2)D(3); 25,26(OH)(2)D(3); and 25(OH)D(3)-26,23-lactone] but not 1alpha,25(OH)(2)D(3). Early assumptions that 1alpha,25(OH)(2)D(3) might cause hypercalcemia in vitamin D toxicity have been replaced by the theories that 25(OH)D(3) at pharmacologic concentrations can overcome vitamin D receptor affinity disadvantages to directly stimulate transcription or that total vitamin D metabolite concentrations displace 1alpha,25(OH)(2)D from vitamin D binding, increasing its free concentration and thus increasing gene transcription. Occasional anecdotal reports from humans intoxicated with vitamin D appear to support the latter mechanism. Although current data support the viewpoint that the biomarker plasma 25(OH)D concentration must rise above 750 nmol/L to produce vitamin D toxicity, the more prudent upper limit of 250 nmol/L might be retained to ensure a wide safety margin.
Topics: Animals; Bone Density Conservation Agents; Ergocalciferols; Half-Life; Humans; Hypercalcemia; Metabolic Clearance Rate; Risk Factors; Toxicology; Vitamin D
PubMed: 18689406
DOI: 10.1093/ajcn/88.2.582S -
Medicina (Kaunas, Lithuania) Feb 2021Vitamin D presents a plethora of different functions that go beyond its role in skeletal homeostasis. It is an efficient endocrine regulator of the... (Review)
Review
Vitamin D presents a plethora of different functions that go beyond its role in skeletal homeostasis. It is an efficient endocrine regulator of the Renin-Angiotensin-Aldosterone System (RAAS) and erythropoiesis, exerts immunomodulatory effects, reduces the cardiovascular events and all-cause mortality. In Chronic Kidney Disease (CKD) patients, Vitamin D function is impaired; the renal hydrolyzation of its inactive form by the action of 1α-hydroxylase declines at the same pace of reduced nephron mass. Moreover, Vitamin D major carrier, the D-binding protein (DBP), is less represented due to Nephrotic Syndrome (NS), proteinuria, and the alteration of the cubilin-megalin-amnionless receptor complex in the renal proximal tubule. In Glomerulonephritis (GN), Vitamin D supplementation demonstrated to significantly reduce proteinuria and to slow kidney disease progression. It also has potent antiproliferative and immunomodulating functions, contributing to the inhibitions of kidney inflammation. Vitamin D preserves the structural integrity of the slit diaphragm guaranteeing protective effects on podocytes. Activated Vitamin D has been demonstrated to potentiate the antiproteinuric effect of RAAS inhibitors in IgA nephropathy and Lupus Nephritis, enforcing its role in the treatment of glomerulonephritis: calcitriol treatment, through Vitamin D receptor (VDR) action, can regulate the heparanase promoter activity and modulate the urokinase receptor (uPAR), guaranteeing podocyte preservation. It also controls the podocyte distribution by modulating mRNA synthesis and protein expression of nephrin and podocin. Maxalcalcitol is another promising alternative: it has about 1/600 affinity to vitamin D binding protein (DBP), compared to Calcitriol, overcoming the risk of hypercalcemia, hyperphosphatemia and calcifications, and it circulates principally in unbound form with easier availability for target tissues. Doxercalciferol, as well as paricalcitol, showed a lower incidence of hypercalcemia and hypercalciuria than Calcitriol. Paricalcitol demonstrated a significant role in suppressing RAAS genes expression: it significantly decreases angiotensinogen, renin, renin receptors, and vascular endothelial growth factor (VEGF) mRNA levels, thus reducing proteinuria and renal damage. The purpose of this article is to establish the Vitamin D role on immunomodulation, inflammatory and autoimmune processes in GN.
Topics: Glomerulonephritis; Humans; Podocytes; Receptors, Calcitriol; Vascular Endothelial Growth Factor A; Vitamin D
PubMed: 33671780
DOI: 10.3390/medicina57020186 -
Kidney International Apr 2011Vitamin D compounds have been used successfully to treat secondary hyperparathyroidism for almost three decades. Side effects of increased levels of serum calcium and... (Review)
Review
Vitamin D compounds have been used successfully to treat secondary hyperparathyroidism for almost three decades. Side effects of increased levels of serum calcium and phosphate and potential complications have increasingly been recognized as problematic, and this has become an even more difficult clinical challenge with the desire to capitalize on some of the pleiotropic effects of vitamin D. Nonclassical nuclear vitamin D receptor (VDR) effects on the cardiovascular system, kidneys, and immune system, with the prospect of improved patient survival, have moved to center stage. Selective vitamin D compounds with minimal effects on mineral metabolism and with maximal cardiovascular and renal benefits are now needed. New vitamin D compounds already in clinical use, which have an improved side-effect profile and differential nonclassical effects compared with calcitriol, are limited to the three licensed pharmaceuticals--paricalcitol, 22-oxacalcitriol, and doxercalciferol. Other compounds are under early development and it is anticipated that these novel therapeutic concepts will result in new vitamin D therapies that will help to reduce the high mortality rate patients with kidney disease experience.
Topics: Animals; Biomarkers; Calcium; Cardiovascular Diseases; Drug Design; Humans; Hyperparathyroidism, Secondary; Phosphates; Receptors, Calcitriol; Signal Transduction; Vitamin D
PubMed: 20962748
DOI: 10.1038/ki.2010.387 -
Molecules (Basel, Switzerland) Sep 2009Alfacalcidol (1alpha-hydroxyvitamin D(3)) has been widely used since 1981 as a prodrug for calcitriol (1alpha,25-dihydroxyvitamin D(3)) in the treatment of hypocalcemia,... (Review)
Review
Alfacalcidol (1alpha-hydroxyvitamin D(3)) has been widely used since 1981 as a prodrug for calcitriol (1alpha,25-dihydroxyvitamin D(3)) in the treatment of hypocalcemia, chronic renal failure, hypoparathyroidism and osteoporosis. More recently, doxercalciferol (1alpha-hydroxyvitamin D(2)) has been used since 1999 as a prodrug for 1alpha,25-dihydroxyvitamin D(2) for the treatment of secondary hyperparathyroidism. Currently, six forms of vitamin D are known. They range from vitamin D(2) to vitamin D(7 )and are distinguished by their differing side chains. Only vitamin D(2) and vitamin D(3) have been found to be biologically active based on the elucidation of activation pathways. Alfacalcidol and osteoporosis/doxercalciferol and secondary hyperparathyroidism are discussed, with a new look at old compounds including their practical syntheses.
Topics: Drug Design; Ergocalciferols; Humans; Hydroxycholecalciferols; Hyperparathyroidism, Secondary; Prodrugs; Rickets; Vitamin D; Vitamins
PubMed: 19924035
DOI: 10.3390/molecules14103869 -
Kidney International Jan 2011We compared the effects of calcitriol and doxercalciferol, in combination with either calcium carbonate or sevelamer, on bone, mineral, and fibroblast growth factor-23... (Comparative Study)
Comparative Study Randomized Controlled Trial
Calcitriol and doxercalciferol are equivalent in controlling bone turnover, suppressing parathyroid hormone, and increasing fibroblast growth factor-23 in secondary hyperparathyroidism.
We compared the effects of calcitriol and doxercalciferol, in combination with either calcium carbonate or sevelamer, on bone, mineral, and fibroblast growth factor-23 (FGF-23) metabolism in patients with secondary hyperparathyroidism. A total of 60 pediatric patients treated with peritoneal dialysis were randomized to 8 months of therapy with either oral calcitriol or doxercalciferol, combined with either calcium carbonate or sevelamer. Bone formation rates decreased during therapy and final values were within the normal range in 72% of patients. A greater improvement in eroded surface was found in patients treated with doxercalciferol than in those given calcitriol. On initial bone biopsy, a mineralization defect was identified in the majority of patients which did not normalize with therapy. Serum phosphate concentrations were controlled equally well by both binders, but serum calcium levels increased during treatment with calcium carbonate, and serum parathyroid hormone levels were decreased by 35% in all groups. Baseline plasma FGF-23 values were significantly elevated and rose over fourfold with calcitriol and doxercalciferol, irrespective of phosphate binder. Thus, doxercalciferol is as effective as calcitriol in controlling serum parathyroid hormone levels and suppressing the bone formation rate. Sevelamer allows the use of higher doses of vitamin D. Implications of these changes on bone and cardiovascular biology remain to be established.
Topics: Adolescent; Bone Density Conservation Agents; Bone and Bones; Calcitriol; Calcium Carbonate; Chronic Kidney Disease-Mineral and Bone Disorder; Drug Therapy, Combination; Ergocalciferols; Female; Fibroblast Growth Factor-23; Fibroblast Growth Factors; Humans; Hypercalcemia; Hyperparathyroidism, Secondary; Hyperphosphatemia; Kidney Failure, Chronic; Longitudinal Studies; Male; Osteogenesis; Parathyroid Hormone; Polyamines; Sevelamer
PubMed: 20861820
DOI: 10.1038/ki.2010.352 -
Indian Journal of Nephrology Jul 2013This study was carried out to evaluate the efficacy and safety of doxercalciferol as therapy for secondary hyperparathyroidism (SHPT) in patients with chronic kidney...
This study was carried out to evaluate the efficacy and safety of doxercalciferol as therapy for secondary hyperparathyroidism (SHPT) in patients with chronic kidney disease (CKD) stage 4 in a prospective clinical trial. A total of 35 CKD-4 patients who had a baseline parathyroid hormone (iPTH) >150 pg/mL and had not received any vitamin D analog in the preceding 8 weeks were followed up at intervals of 6 weeks for 18 weeks on oral therapy with doxercalciferol. The starting dose was 1.5 μg/day, and the dose was increased in steps of 1 μg/day if iPTH did not decrease by at least 30% on the subsequent visit. Doxercalciferol was stopped temporarily if low iPTH (<70 pg/mL), hypercalcemia (>10.7 mg/dL), or severe hyperphosphatemia (>8.0 mg/dL) occurred, and was restarted at a lower dose on reversal of these abnormalities. Calcium acetate was the only phosphate binder used. Mean iPTH decreased by 35.4 ± 4.4% from 381.7 ± 31.3 pg/mL to 237.9 ± 25.7 pg/mL (P < 0.001). The proportion of patients who achieved 30% and 50% suppression of iPTH levels was 83% and 72%, respectively. Mean serum calcium, phosphorus, and calcium-phosphorus product values did not differ significantly from the baseline values. Four, two, and nine patients developed hypercalcemia, severe hyperphosphatemia, and high CaxP (>55), respectively. Almost all patients recovered to an acceptable level within 2 weeks of stopping doxercalciferol and adjusting the phosphate binder dose. In all, 21 patients required temporary stoppage of therapy. Most of them were restarted on therapy at a reduced dose during the study. It can, therefore, be concluded that doxercalciferol is effective in controlling SHPT in CKD-4 patients with an acceptable risk of hyperphosphatemia and hypercalcemia.
PubMed: 23960343
DOI: 10.4103/0971-4065.114492 -
Nutrients Mar 2023Lifestyle habits and insufficient sunlight exposure lead to a high prevalence of vitamin D hypovitaminosis, especially in the elderly. Recent studies suggest that in... (Review)
Review
Lifestyle habits and insufficient sunlight exposure lead to a high prevalence of vitamin D hypovitaminosis, especially in the elderly. Recent studies suggest that in central Europe more than 50% of people over 60 years are not sufficiently supplied with vitamin D. Since vitamin D hypovitaminosis is associated with many diseases, such as Alzheimer's disease (AD), vitamin D supplementation seems to be particularly useful for this vulnerable age population. Importantly, in addition to vitamin D, several analogues are known and used for different medical purposes. These vitamin D analogues differ not only in their pharmacokinetics and binding affinity to the vitamin D receptor, but also in their potential side effects. Here, we discuss these aspects, especially those of the commonly used vitamin D analogues alfacalcidol, paricalcitol, doxercalciferol, tacalcitol, calcipotriol, and eldecalcitol. In addition to their pleiotropic effects on mechanisms relevant to AD, potential effects of vitamin D analogues on comorbidities common in the context of geriatric diseases are summarized. AD is defined as a complex neurodegenerative disease of the central nervous system and is commonly represented in the elderly population. It is usually caused by extracellular accumulation of amyloidogenic plaques, consisting of amyloid (Aβ) peptides. Furthermore, the formation of intracellular neurofibrillary tangles involving hyperphosphorylated tau proteins contributes to the pathology of AD. In conclusion, this review emphasizes the importance of an adequate vitamin D supply and discusses the specifics of administering various vitamin D analogues compared with vitamin D in geriatric patients, especially those suffering from AD.
Topics: Humans; Aged; Alzheimer Disease; Neurodegenerative Diseases; Vitamin D; Vitamins; tau Proteins; Amyloid beta-Peptides
PubMed: 37049524
DOI: 10.3390/nu15071684 -
PloS One 2015Osteocytic protein expression is dysregulated in CKD and is affected by changes in mineral metabolism; however the effects of active vitamin D sterol therapy on...
BACKGROUND
Osteocytic protein expression is dysregulated in CKD and is affected by changes in mineral metabolism; however the effects of active vitamin D sterol therapy on osteocyte protein expression in advanced CKD is unknown.
METHODS
Eleven pediatric patients with end stage kidney disease underwent bone biopsy, were treated for 8 months with doxercalciferol, and then underwent a second bone biopsy. Bone expression of fibroblast growth factor 23 (FGF23), dentin matrix protein 1 (DMP1), and sclerostin were determined by immunohistochemistry and quantified by Ariol Scanning. Western blot analysis and qRT-PCR was performed on bone abstracts of a subset of study subjects to determine the nature (i.e. size) of FGF23 and DMP1 in bone before and after therapy.
RESULTS
As assessed by immunohistochemistry, bone FGF23, DMP1 and sclerostin protein all increased with therapy. In the case of FGF23, this increase was due to an increase in the full-length molecule without the appearance of FGF23 fragments. DMP1 was present primarily in its full-length form in healthy controls while 57kDa and 37kDa fragments of DMP1 were apparent in bone of dialysis patients at baseline and the 57 kDa appeared to decrease with therapy.
CONCLUSION
Marked changes in osteocytic protein expression accompany doxercalciferol therapy, potentially impacting bone mineralization and the skeletal response to PTH. The effects of these bone changes on long-term outcomes remain to be determined.
Topics: Adaptor Proteins, Signal Transducing; Adolescent; Biopsy; Bone Density Conservation Agents; Bone Morphogenetic Proteins; Bone and Bones; Child; Ergocalciferols; Extracellular Matrix Proteins; Female; Fibroblast Growth Factor-23; Fibroblast Growth Factors; Gene Expression; Genetic Markers; Humans; Kidney Failure, Chronic; Male; Osteocytes; Osteolysis; Phosphoproteins; Renal Dialysis; Treatment Outcome
PubMed: 25774916
DOI: 10.1371/journal.pone.0120856 -
PloS One 2023Identifying novel therapeutic agents is a fundamental challenge in contemporary drug development, especially in the context of complex diseases like cancer,...
Identifying novel therapeutic agents is a fundamental challenge in contemporary drug development, especially in the context of complex diseases like cancer, neurodegenerative disorders, and metabolic syndromes. Here, we present a comprehensive computational study to identify potential inhibitors of SIRT1 (Sirtuin 1), a critical protein involved in various cellular processes and disease pathways. Leveraging the concept of drug repurposing, we employed a multifaceted approach that integrates molecular docking and molecular dynamics (MD) simulations to predict the binding affinities and dynamic behavior of a diverse set of FDA-approved drugs from DrugBank against the SIRT1. Initially, compounds were shortlisted based on their binding affinities and interaction analyses to identify safe and promising binding partners for SIRT1. Among these candidates, Doxercalciferol and Timiperone emerged as potential candidates, displaying notable affinity, efficiency, and specificity towards the binding pocket of SIRT1. Extensive evaluation revealed that these identified compounds boast a range of favorable biological properties and prefer binding to the active site of SIRT1. To delve deeper into the interactions, all-atom MD simulations were conducted for 500 nanoseconds (ns). These simulations assessed the conformational dynamics, stability, and interaction mechanism of the SIRT1-Doxercalciferol and SIRT1-Timiperone complexes. The MD simulations illustrated that the SIRT1-Doxercalciferol and SIRT1-Timiperone complexes maintain stability over a 500 ns trajectory. These insightful outcomes propose that Doxercalciferol and Timiperone hold promise as viable scaffolds for developing potential SIRT1 inhibitors, with implications for tackling complex diseases such as cancer, neurodegenerative disorders, and metabolic syndromes.
Topics: Humans; Molecular Dynamics Simulation; Sirtuin 1; Molecular Docking Simulation; Drug Repositioning; Metabolic Syndrome; Neoplasms; Neurodegenerative Diseases
PubMed: 38117829
DOI: 10.1371/journal.pone.0293185