A novel vitamin D derivative activates bone morphogenetic protein signaling in MCF10 breast epithelial cells

The Effect of Vitamin D3 and Valproic Acid on the Maturation of Human-Induced Pluripotent Stem Cell-Derived Enterocyte-Like Cells

Cytochrome P450 3A4 (CYP3A4) is involved in first-pass metabolism in the small intestine and is heavily implicated in oral drug bioavailability and pharmacokinetics. We previously reported that vitamin D3 (VD3), a known CYP enzyme inducer, induces functional maturation of iPSC-derived enterocyte-like cells (iPSC-ent). Here, we identified a Notch activator and CYP modulator valproic acid (VPA), as a promotor for the maturation of iPSC-ent. We performed bulk RNA sequencing to investigate the changes in gene expression during the differentiation and maturation periods of these cells. VPA potentiated gene expression of key enterocyte markers ALPI, FABP2, and transporters such as SULT1B1. RNA-sequencing analysis further elucidated several function-related pathways involved in fatty acid metabolism, significantly upregulated by VPA when combined with VD3. Particularly, VPA treatment in tandem with VD3 significantly upregulated key regulators of enterohepatic circulation, such as FGF19, apical bile acid transporter SLCO1A2 and basolateral bile acid transporters SLC51A and SLC51B. To sum up, we could ascertain the genetic profile of our iPSC-ent cells to be specialized toward fatty acid absorption and metabolism instead of transporting other nutrients, such as amino acids, with the addition of VD3 and VPA in tandem. Together, these results suggest the possible application of VPA-treated iPSC-ent for modelling enterohepatic circulation.

The Centennial Collection of VDR Ligands: Metabolites, Analogs, Hybrids and Non-Secosteroidal Ligands

Since the discovery of vitamin D a century ago, a great number of metabolites, analogs, hybrids and nonsteroidal VDR ligands have been developed. An enormous effort has been made to synthesize compounds which present beneficial properties while attaining lower calcium serum levels than calcitriol. This structural review covers VDR ligands published to date.

Vitamin D Analogs Bearing C-20 Modifications Stabilize the Agonistic Conformation of Non-Responsive Vitamin D Receptor Variants

The Vitamin D receptor (VDR) plays a key role in calcium homeostasis, as well as in cell proliferation and differentiation. Among the large number of VDR ligands that have been developed, we have previously shown that BXL-62 and Gemini-72, two C-20-modified vitamin D analogs are highly potent VDR agonists. In this study, we show that both VDR ligands restore the transcriptional activities of VDR variants unresponsive to the natural ligand and identified in patients with rickets. The elucidated mechanisms of action underlying the activities of these C-20-modified analogs emphasize the mutual adaptation of the ligand and the VDR ligand-binding pocket.

Targeting cancer stem cells in solid tumors by vitamin D

Cancer stem cells (CSCs) are a small subset of cells that may be responsible for initiation, progression, and recurrence of tumors. Recent studies have demonstrated that CSCs are highly tumorigenic and resistant to conventional chemotherapies, making them a promising target for the development of preventive/therapeutic agents. A single or combination of various markers, such as CD44, EpCAM, CD49f, CD133, CXCR4, ALDH-1, and CD24, were utilized to isolate CSCs from various types of human cancers. Notch, Hedgehog, Wnt, and TGF-β signalingregulate self-renewal and differentiation of normal stem cells andare aberrantly activated in CSCs. In addition, many studies have demonstrated that these stem cell-associated signaling pathways are required for the maintenance of CSCs in different malignancies, including breast, colorectal, prostate, and pancreatic cancers. Accumulating evidence has shown inhibitory effects of vitamin D and its analogs on the cancer stem cell signaling pathways, suggesting vitamin D as a potential preventive/therapeutic agent against CSCs. In this review, we summarize recent findings about the roles of Notch, Hedgehog, Wnt, and TGF-β signaling in CSCs as well as the effects of vitamin D on these stem cell signaling pathways. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.

Comparative regulation of gene expression by 1,25-dihydroxyvitamin D3 in cells derived from normal mammary tissue and breast cancer

Previous genomic profiling of immortalized, non-tumorigenic human breast epithelial cells identified a set of 1,25-dihydroxyvitamin D3 (1,25D) regulated genes with potential relevance to breast cancer prevention. In this report, we characterized the effect of 1,25D on a subset of these genes in six cell lines derived from mammary tissue and breast cancers. Non-tumorigenic cell lines included hTERT-HME1, HME and MCF10A cells which are often used to model normal breast epithelial cells. Breast cancer cell lines included MCF7 cells (a model of early stage, estrogen-dependent disease), DCIS.com cells (a derivative of MCF10A cells that models in situ breast cancer) and Hs578T cells (a model of metastatic disease). All of these cell lines express the vitamin D receptor (VDR) and exhibit anti-cancer responses to 1,25D such as changes in proliferation, apoptosis, metabolism, or invasion. Our comparative data demonstrate highly variable responses to 1,25D (100nM, 24h) between the cell lines. In both hTERT-HME1 and HME cell lines, CYP24A1, SLC1A1 and ITGB3 were up-regulated whereas KDR, GLUL and BIRC3 were down-regulated in response to 1,25D. In contrast, no changes in SLC1A1, ITGB3 or GLUL expression were detected in 1,25D treated MCF10A cells although KDR and BIRC3 were down-regulated by 1,25D. The effects of 1,25D on these genes in the breast cancer cell lines were blunted, with the DCIS.com cells exhibiting the most similar responses to the immortalized hTERT-HME1 and HME cells. The differences in cellular responses were not due to general impairment in VDR function as robust CYP24A1 induction was observed in all cell lines. Thus, our data indicate that the genomic changes induced by 1,25D are highly cell-type specific even in model cell lines derived from the same tissue. The implication of these findings is that genomic responses to changes in vitamin D status in vivo are likely to be distinct from individual to individual, particularly in neoplastic tissue. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.

Calcitriol derivatives with two different side chains at C-20. V. Potent inhibitors of mammary carcinogenesis and inducers of leukemia differentiation

Calcitriol is implicated in many cellular functions including cellular growth and differentiation, thus explaining its antitumor effects. It was shown that gemini, the calcitriol derivative containing two side chain at C20, is also active in gene transcription with enhanced antitumor activity. We have now further optimized both the A-ring and the two side chains. The chemical structures of the resulting 18 geminis were correlated with biological activities. Those containing the 1alpha-fluoro A-ring are the least active. Those featuring 23-yne and 23(E) side-chains are generally more active in human breast cancer cell growth inhibition and human leukemia cell differentiation induction than their 23(Z) counterparts. On the basis of these evaluations, we selected as lead compound a 20(R) gemini, related to calcitriol in terms of it is A-ring, where one side chain was modified by introduction of a 23-yne function and replacement of the geminal methyl groups with trifluoromethyl groups, the other created by extension of C21 with a 3-hydroxy-3-trideuteromethyl-4,4,4-trideutero-butyl moiety.

Anti-inflammatory action of pterostilbene is mediated through the p38 mitogen-activated protein kinase pathway in colon cancer cells

Oxidative/nitrosative stress and generation of proinflammatory cytokines are hallmarks of inflammation. Because chronic inflammation is implicated in several pathologic conditions in humans, including cancers of the colon, anti-inflammatory compounds may be useful chemopreventive agents against colon cancer. Stilbenes, such as resveratrol, have diverse pharmacologic activities, which include anti-inflammation, cancer prevention, a cholesterol-lowering effect, enhanced insulin sensitivity, and increased life span. We previously showed that pterostilbene (trans-3,5-dimethoxy-4'-hydroxystilbene), a structural analogue of resveratrol, is present in blueberries and that pterostilbene inhibited expression of certain inflammation-related genes in the colon and suppressed aberrant crypt foci formation in rats. Here, we examined molecular mechanisms of the action of pterostilbene in colon cancer. Pterostilbene reduced cell proliferation, down-regulated the expression of c-Myc and cyclin D1, and increased the level of cleaved poly(ADP-ribose) polymerase. A combination of cytokines (tumor necrosis factor-alpha, IFN-gamma, and bacterial endotoxin lipopolysaccharide) induced inflammation-related genes such as inducible nitric oxide synthase and cyclooxygenase-2, which was significantly suppressed by treatment with pterostilbene. We further identified upstream signaling pathways contributing to the anti-inflammatory activity of pterostilbene by investigating multiple signaling pathways, including nuclear factor-kappaB, Janus-activated kinase-signal transducer and activator of transcription, extracellular signal-regulated kinase, p38, c-Jun NH(2)-terminal kinase, and phosphatidylinositol 3-kinase. Cytokine induction of the p38-activating transcription factor 2 pathway was markedly inhibited by pterostilbene among the different mediators of signaling evaluated. By silencing the expression of the p38 alpha isoform, there was significant reduction in cytokine induction of inducible nitric oxide synthase and cyclooxygenase-2. Our data suggest that the p38 mitogen-activated protein kinase cascade is a key signal transduction pathway for eliciting the anti-inflammatory action of pterostilbene in cultured HT-29 colon cancer cells.

Gemini vitamin D analogues inhibit estrogen receptor-positive and estrogen receptor-negative mammary tumorigenesis without hypercalcemic toxicity

Numerous preclinical, epidemiologic, and clinical studies have suggested the benefits of vitamin D and its analogues for the prevention and treatment of cancer. However, the hypercalcemic effects have limited the use of 1alpha,25(OH)(2)D(3), the hormonally active form of vitamin D. To identify vitamin D analogues with better efficacy and low toxicity, we have tested >60 novel Gemini vitamin D analogues with a unique structure of two side chains for growth inhibition of breast cancer cells. Our initial studies found that some Gemini analogues are 5-15 times more active than 1alpha,25(OH)(2)D(3) in growth inhibition assay. In vivo experiments were designed to study the inhibitory effect of selected Gemini vitamin D analogues against mammary carcinogenesis by using (a) an N-methyl-N-nitrosourea-induced estrogen receptor (ER)-positive mammary tumor model and (b) an MCF10DCIS.com xenograft model of ER-negative mammary tumors. Among vitamin D analogues we tested, Gemini 0072 [1alpha,25-dihydroxy-20S-21(3-trideuteromethyl-3-hydroxy-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-19-nor-cholecalciferol] and Gemini 0097 [1alpha,25-dihydroxy-20R-21(3-trideuteromethyl-3-hydroxy-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-19-nor-cholecalciferol] administration inhibited by 60% the NMU-induced mammary tumor burden compared with the NMU-treated control group, but these compounds were devoid of hypercalcemia toxicity. In an ER-negative xenograft model, Gemini 0097 significantly suppressed tumor growth without hypercalcemia toxicity. We found that the inhibitory effect of Gemini 0097 was associated with an increased level of cyclin-dependent kinase inhibitor p21 and the insulin-like growth factor binding protein 3 in both ER-positive and ER-negative mammary tumors. Our results suggest that Gemini vitamin D analogues may be potent agents for the prevention and treatment of both ER-positive and ER-negative breast cancer without hypercalcemia toxicity.

Endogenous bone morphogenetic proteins mediate 1alpha, 25-dihydroxyvitamin D(3)-induced expression of osteoblast differentiation markers in human dermal fibroblasts

Human dermal fibroblasts are generally considered to be restricted to a fibroblastic lineage. Although dermal fibroblasts do not typically express markers of osteoblastic differentiation, they have previously been shown to undergo osteoinduction when stimulated with bone morphogenetic proteins (BMPs) or vitamin D(3). However, involvement of BMP signaling in vitamin D(3)-mediated osteoinduction has not been reported. In this study, human dermal fibroblasts were cultured in chemically defined medium containing vitamin D(3), in the presence of the BMP antagonist noggin or neutralizing antibodies specific for BMP-4 or BMP-6, and characterized for markers of osteoblastic differentiation. Treatment of dermal fibroblasts with vitamin D(3) induced expression of BMP-4 (1.2 +/- 0.2, 1.7 +/- 0.2, and 1.8 +/- 0.2 relative fold increase) and BMP-6 (9.1 +/- 0.3, 23.3 +/- 2.1, and 30.4 +/- 3.0 relative fold increase) at 3, 14, and 21 days, respectively. Vitamin D(3) was also shown to induce the expression of the osteoblast-specific markers, alkaline phosphatase and osteocalcin, in a dose-dependent manner in human dermal fibroblasts. Addition of noggin, BMP-4 antibodies, and BMP-6 antibodies resulted in a downregulation of alkaline phosphatase activity (by 42%, 22%, and 20%, respectively) and secreted osteocalcin (by 20%, 31%, and 49%, respectively) after 21 days in culture. However, blocking BMP signaling did not result in complete recovery of a fibroblastic phenotype. Taken together, these results suggest that BMP signaling plays a role in the induction of an osteoblastic phenotype in human dermal fibroblasts in response to vitamin D(3) stimulation.

Vitamin D reduces the expression of collagen and key profibrotic factors by inducing an antifibrotic phenotype in mesenchymal multipotent cells

Hypovitaminosis D is an important public health problem. Serum 25-hydroxyvitamin D (25-OHD) is now recognized as an independent predictor for cardiovascular and related diseases (CVD) as well as other chronic medical conditions. However, the biologic pathways through which these effects are mediated remain poorly understood. We hypothesized that exposing mesenchymal multipotent cells (MMCs) to the active form of vitamin D would increase the expression of selected antifibrotic factors that in turn would ameliorate the progression of chronic diseases. MMCs were primed with 5'-azacytidine to induce a fibrotic phenotype and then treated with active vitamin D (1,25D) or ethanol <0.1% as vehicle in a time course manner (30 min, 1, 5, and 24 h, and for 4 and 7 days). The addition of 1,25D to MMCs promotes: a) increased expression and nuclear translocation of the vitamin D receptor; b) decreased expression of TGFB1 and plasminogen activator inhibitor (SERPINE1), two well-known profibrotic factors; c) decreased expression of collagen I, III and other collagens isoforms; and d) increased expression of several antifibrotic factors such as BMP7 a TGFB1 antagonist, MMP8 a collagen breakdown inducer and follistatin, an inhibitor of the profibrotic factor myostatin. In conclusion, the addition of 1,25D to differentiated MMCs displays a decreased profibrotic signaling pathway and gene expression, leading to decrease in collagen deposition. This study highlights key mechanistic pathways through which vitamin D decreases fibrosis, and provides a rationale for studies to test vitamin D supplementation as a preventive and/or early treatment strategy for CVD and related fibrotic disorders.

Activation of bone morphogenetic protein signaling by a Gemini vitamin D3 analogue is mediated by Ras/protein kinase C alpha

Bone morphogenetic proteins (BMP) are members of the transforming growth factor-beta superfamily, and they play an important role for embryonic development, for bone and cartilage formation, and during carcinogenesis. We have previously shown that the novel Gemini vitamin D(3) analogue, Ro-438-3582 [Ro3582; 1 alpha,25-dihydroxy-20S,21(3-hydroxy-3-methylbutyl)-23-yne-26,27-hexafluorocholecalciferol], inhibited cell proliferation and activated the BMP/Smad signaling pathway in MCF10AT1 breast epithelial cells. In this report, we investigated the upstream signaling pathways responsible for the activation of BMP/Smad signaling by Ro3582. Among seven different serine/threonine kinase inhibitors that we tested, protein kinase C (PKC) inhibitors blocked the effects of Ro3582 on the phosphorylation of Smad1/5, mRNA synthesis for BMP-2 and BMP-6, and cell growth in MCF10AT1 cells. Overexpression of PKC alpha, but not PKC epsilon, PKC delta or PKC zeta isoforms, increased Ro3582-induced phosphorylation of Smad1/5, suggesting that PKC alpha mediates the activation of Smad signaling and inhibition of cell proliferation. Interestingly, the activation of Smad signaling by Ro3582 was shown in Ha-ras-transfected MCF10AT1 cells, but not in the parent cell line (MCF10A without Ras). Inhibiting Ras activity blocked the translocation of PKC alpha to the plasma membrane and the phosphorylation of Smad1/5 induced by Ro3582, indicating that Ras is necessary for the activation of PKC alpha and Smad signaling. In conclusion, Ro3582 inhibits cell proliferation and activates BMP/Smad signaling via a Ras and PKC alpha pathway in breast epithelial cells.

Gene expression profiling changes induced by a novel Gemini Vitamin D derivative during the progression of breast cancer

We investigated gene expression changes induced by a novel Gemini Vitamin D(3) analog, RO-438-3582 (1alpha,25-dihydroxy-20S-21(3-hydroxy-3-methyl-butyl)-23-yne-26,27-hexafluoro-cholecalciferol, Ro3582), in a unique human breast MCF10 model. We used two breast epithelial cell lines from this model, namely MCF10AT1 (Ha-ras oncogene transfected MCF10A, early premalignant) and MCF10CA1a (fully malignant and metastatic derived from the MCF10AT1 line). We analyzed gene expression changes induced by Ro3582 using GeneChip technology, quantitative RT-PCR, Western blot analysis, or a gene transcription assay. Interestingly, we found distinct gene expression profile differences between Ro3582-induced response of the early premalignant MCF10AT1 and the malignant and metastatic MCF10CA1a cell lines. Moreover, while the Gemini Vitamin D(3) analog Ro3582 modulated the expression of several Vitamin D target genes such as the 24-hydroxylase, CD14, osteocalcin, and osteopontin in both cell lines, Ro3582 regulated many genes involved in cell proliferation and apoptosis, cell adhesion, invasion, angiogenesis as well as cell signaling pathways, such as the BMP and TGF-beta systems, differently in the two cell lines. The Gemini Vitamin D(3) analog Ro3582 induced more significant gene changes in the early premalignant MCF10AT1 cells than in the malignant metastatic MCF10CA1a cells, suggesting that Gemini Vitamin D(3) analogs may be more effective in preventing the progression of an early stage of breast carcinogenesis than in treating late stage breast cancer.