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Vitamin D receptor ligands have potential for the treatment of hyperproliferative diseases and disorders related to the immune system. However, hypercalcemic effects limit their therapeutical uses and call for the development of tissue-selective new analogs. We have designed and synthesized the first examples of 1α,25-dihydroxyvitamin D 3 analogs bearing an allenic unit attached to the D ring to restrict the side-chain conformational mobility. The triene system was constructed by a Pd 0 -mediated cyclization/Suzuki-Miyaura cross-coupling process in the presence of an allenic side chain. The allenic moiety was built through an orthoester-Claisen rearrangement of a propargylic alcohol. The biological activity and structure of (22S)-1α,25-dihydroxy-17,20-dien-24-homo-21-nor-vitamin D 3 bound to binding domain of the vitamin D receptor, provide information concerning side-chain conformational requirements for biological activity., (© 2021 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

Deficiency in 1alpha,25-dihydroxyvitamin D(3) (1,25D(3)) has been suggested as an important environmental factor for immuno-mediated disorders including inflammatory bowel diseases (IBD), comprising Crohn's disease and ulcerative colitis, both characterized by chronic intestinal inflammation. Administration of vitamin D receptor (VDR) agonists can ameliorate spontaneous and induced animal models of colitis, but hypercalcemia is a dose-limiting adverse event. Previous work in our laboratory has identified 1alpha,25(OH)(2)-16-ene-20-cyclopropyl-vitamin D(3) (BXL-62) as a potent anti-inflammatory VDR agonist with a low calcemic activity. In the present study, we confirm the marked anti-inflammatory properties of BXL-62 and show its capacity to induce VDR primary response genes, like CYP24A1 and CAMP, at lower concentrations than 1,25D(3), in PBMCs from IBD patients. Its higher anti-inflammatory potency compared to 1,25D(3) was demonstrated by the significantly more potent inhibition in PBMCs and in lymphocyte-enriched lamina propria mononuclear cells of the pro-inflammatory cytokines TNF-alpha, IL-12/23p40, IL-6 and IFN-gamma, both at mRNA and protein level. The therapeutic efficacy of intra-rectal administration of BXL-62 in experimental IBD is shown by its beneficial effects, significantly higher than 1,25D(3), to induce recovery of clinical symptoms of colitis at normocalcemic doses in mice undergoing dextran sodium sulfate-induced colitis. These results confirm the therapeutic efficacy of VDR agonists in experimental colitis, and suggest BXL-62 as a promising compound for IBD treatment., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)

1alpha,25(OH)(2)-16-ene-20-cyclopropyl-vitamin D(3) (13) is several fold more potent than the natural hormone 1alpha,25-dihydroxyvitamin D(3) (1) as an anti-inflammatory agent. Here, we have further analyzed the anti-inflammatory properties of 13, confirming it as the most potent analogue tested within this family. We then determined the structures of all the natural metabolites of 13, including the 24-oxo metabolite 14, and carried out its synthesis. A comparison of 13 with 14 showed a similar induction of the primary VDR target genes CYP24A1 and CAMP and comparable anti-inflammatory properties as revealed by a similar inhibition of TNF-alpha, IL-12/23p40, IL-6, and IFN-gamma production. Interestingly, 14 displays a 3-fold lower calcemic activity in vivo compared to 13. Collectively, these findings indicate that the strong potency of 13 can be explained by the accumulation of its stable 24-oxo metabolite, which shows immunoregulatory and anti-inflammatory properties superimposable to those exerted by 13 itself.

Background: Benign prostatic hyperplasia (BPH) is characterized by an important inflammatory component. Stimulation of human prostate stromal cells from BPH tissues with proinflammatory cytokines leads to secretion of IL-8, a chemokine involved in BPH pathogenesis. The vitamin D receptor (VDR) agonist elocalcitol can arrest prostate growth in BPH patients, but its mechanism of action in this pathology is still incompletely understood., Methods: IL-8 levels were measured by real-time RT-PCR and ELISA. NF-kappaB translocation and COX-2 expression were evaluated by confocal microscopy. RhoA and Rho-kinase (ROCK) gene expression and functional activity were studied by real-time RT-PCR, immuno-kinase assays, Western blot analysis, confocal microscopy, and cell invasion., Results: Stimulation of BPH cells with IL-8 activates the calcium-sensitizing RhoA/ROCK pathway, as demonstrated by the increased membrane translocation of RhoA and by phosphorylation of the ROCK substrate myosin phosphatase target subunit 1 (MYPT-1). In agreement with these data, C3 exoenzyme, a selective RhoA inhibitor, inhibits IL-8-induced invasion of BPH cells. The VDR agonist elocalcitol significantly inhibits IL-8 production by BPH cells stimulated with inflammatory cytokines, and IL-8-induced proliferation of BPH cells. In addition, elocalcitol inhibits IL-8-induced membrane translocation of RhoA and MYPT-1 phosphorylation in BPH cells, and inhibits dose-dependently their IL-8-dependent invasion. The inhibition induced by elocalcitol of IL-8 production by BPH cells is accompanied by decreased COX-2 expression and PGE(2) production and by arrest of NF-kappaB p65 nuclear translocation, associated with inhibition of the RhoA/ROCK pathway., Conclusions: These data provide a mechanistic explanation for the anti-proliferative and anti-inflammatory properties of elocalcitol in BPH cells., ((c) 2008 Wiley-Liss, Inc.)