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

Vitamin D as a Potential Preventive Agent For Young Women's Breast Cancer

Clinical studies backed by research in animal models suggest that vitamin D may protect against the development of breast cancer, implicating vitamin D as a promising candidate for breast cancer prevention. However, despite clear preclinical evidence showing protective roles for vitamin D, broadly targeted clinical trials of vitamin D supplementation have yielded conflicting findings, highlighting the complexity of translating preclinical data to efficacy in humans. While vitamin D supplementation targeted to high-risk populations is a strategy anticipated to increase prevention efficacy, a complimentary approach is to target transient, developmental windows of elevated breast cancer risk. Postpartum mammary gland involution represents a developmental window of increased breast cancer promotion that may be poised for vitamin D supplementation. Targeting the window of involution with short-term vitamin D intervention may offer a simple, cost-effective approach for the prevention of breast cancers that develop postpartum. In this review, we highlight epidemiologic and preclinical studies linking vitamin D deficiency with breast cancer development. We discuss the underlying mechanisms through which vitamin D deficiency contributes to cancer development, with an emphasis on the anti-inflammatory activity of vitamin D. We also discuss current evidence for vitamin D as an immunotherapeutic agent and the potential for vitamin D as a preventative strategy for young woman's breast cancer.

Is Vitamin D Deficiency Related to Increased Cancer Risk in Patients with Type 2 Diabetes Mellitus?

There is mounting evidence that type 2 diabetes mellitus (T2DM) is related with increased risk for the development of cancer. Apart from shared common risk factors typical for both diseases, diabetes driven factors including hyperinsulinemia, insulin resistance, hyperglycemia and low grade chronic inflammation are of great importance. Recently, vitamin D deficiency was reported to be associated with the pathogenesis of numerous diseases, including T2DM and cancer. However, little is known whether vitamin D deficiency may be responsible for elevated cancer risk development in T2DM patients. Therefore, the aim of the current review is to identify the molecular mechanisms by which vitamin D deficiency may contribute to cancer development in T2DM patients. Vitamin D via alleviation of insulin resistance, hyperglycemia, oxidative stress and inflammation reduces diabetes driven cancer risk factors. Moreover, vitamin D strengthens the DNA repair process, and regulates apoptosis and autophagy of cancer cells as well as signaling pathways involved in tumorigenesis i.e., tumor growth factor β (TGFβ), insulin-like growth factor (IGF) and Wnt-β-Cathenin. It should also be underlined that many types of cancer cells present alterations in vitamin D metabolism and action as a result of Vitamin D Receptor (VDR) and CYP27B1 expression dysregulation. Although, numerous studies revealed that adequate vitamin D concentration prevents or delays T2DM and cancer development, little is known how the vitamin affects cancer risk among T2DM patients. There is a pressing need for randomized clinical trials to clarify whether vitamin D deficiency may be a factor responsible for increased risk of cancer in T2DM patients, and whether the use of the vitamin by patients with diabetes and cancer may improve cancer prognosis and metabolic control of diabetes.

The Vitamin D Receptor as Tumor Suppressor in Skin

Cutaneous malignancies including melanomas and keratinocyte carcinomas (KC) are the most common types of cancer, occurring at a rate of over one million per year in the United States. KC, which include both basal cell carcinomas and squamous cell carcinomas, are substantially more common than melanomas and form the subject of this chapter. Ultraviolet radiation (UVR), both UVB and UVA, as occurs with sunlight exposure is generally regarded as causal for these malignancies, but UVB is also required for vitamin D synthesis in the skin. Keratinocytes are the major cell in the epidermis. These cells not only produce vitamin D but contain the enzymatic machinery to metabolize vitamin D to its active metabolite, 1,25(OH)₂D, and express the receptor for this metabolite, the vitamin D receptor (VDR). This allows the cell to respond to the 1,25(OH)₂D that it produces. Based on our own data and that reported in the literature, we conclude that vitamin D signaling in the skin suppresses UVR-induced epidermal tumor formation. In this chapter we focus on four mechanisms by which vitamin D signaling suppresses tumor formation. They are inhibition of proliferation/stimulation of differentiation with discussion of the roles of hedgehog, Wnt/β-catenin, and hyaluronan/CD44 pathways in mediating vitamin D regulation of proliferation/differentiation, regulation of the balance between oncogenic and tumor suppressor long noncoding RNAs, immune regulation, and promotion of DNA damage repair (DDR).

Vitamin D metabolism in dogs and cats and its relation to diseases not associated with bone metabolism

Due to the presence of receptors in the cells of numerous body tissues, vitamin D is associated with several physiological functions that go beyond calcium and phosphorus homoeostasis and control of bone metabolism in the body. In humans, several studies have associated lower vitamin D concentrations with numerous diseases, such as cancer, heart disease, autoimmune diseases and infectious diseases, and also with an increase in the total mortality rate of the population. Recently, this nutrient started to gain importance in veterinary medicine, and several articles have shown a correlation between low vitamin D status and diseases unrelated to bone metabolism. The present review aims to highlight the recent publications that investigated this relationship, bringing the evidence that exists so far in dogs and cats.

Tocopherols inhibit estrogen-induced cancer stemness and OCT4 signaling in breast cancer

Estrogen plays an important role in breast cancer development. While the mechanism of the estrogen effects is not fully elucidated, one possible route is by increasing the stem cell-like properties in the tumors. Tocopherols are known to reduce breast cancer development and progression. The aim of the present study is to investigate the effects of tocopherols on the regulation of breast cancer stemness mediated by estrogen. To determine the effects of tocopherols on estrogen-influenced breast cancer stem cells, the MCF-7 tumorsphere culture system, which enriches for mammary progenitor cells and putative breast cancer stem cells, was utilized. Treatment with estrogen resulted in an increase in the CD44+/CD24- subpopulation and aldehyde dehydrogenase activity in tumorspheres as well as the number and size of tumorspheres. Tocopherols inhibited the estrogen-induced expansion of the breast cancer stem population. Tocopherols decreased the levels of stem cell markers, including octamer-binding transcription factor 4 (OCT4), CD44 and SOX-2, as well as estrogen-related markers, such as trefoil factor (TFF)/pS2, cathepsin D, progesterone receptor and SERPINA1, in estrogen-stimulated tumorspheres. Overexpression of OCT4 increased CD44 and sex-determining region Y-box-2 levels and significantly increased cell invasion and expression of the invasion markers, matrix metalloproteinases, tissue inhibitors of metalloproteinase and urokinase plasminogen activator, and tocopherols inhibited these OCT4-mediated effects. These results suggest a potential inhibitory mechanism of tocopherols in estrogen-induced stemness and cell invasion in breast cancer.

Role of vitamin D and vitamin D receptor (VDR) in oral cancer

Oral cancer is known as one of the most common cancers, with a poor prognosis, related to delayed clinical diagnosis, either due to the lack of particular biomarkers related to the disease or costly therapeutic alternatives. Vitamin D executes its functions by interacting with the vitamin D receptor (VDR), both in healthy and diseased individuals, including oral cancer. This review discusses the role of vitamin D and VDR on tumorigenesis, emphasizing on oral cancer. Furthermore, regulation of VDR expression, mechanisms of anticancer effects of calcitriol, oral cancer chemoresistance and its relation with VDR and polymorphisms of VDR gene will be discussed. The manuscript is prepared mainly using the information collected from PubMed and MEDLINE.

A more reliable synthesis of a Gemini vitamin D analog, a potentially effective chemotherapeutic agent for the treatment of colorectal carcinomas

After a serendipitous synthesis of a potentially effective chemotherapeutic agent for the treatment of colorectal carcinomas, a more reliable synthetic method is now described using our building blocks containing stereodefined stereochemistry at C-20.

Differential Gene Regulation and Tumor-Inhibitory Activities of Alpha-, Delta-, and Gamma-Tocopherols in Estrogen-Mediated Mammary Carcinogenesis

Despite experimental evidence elucidating the antitumor activities of tocopherols, clinical trials with α-tocopherol (α-T) have failed to demonstrate its beneficial effects in cancer prevention. This study compared the chemopreventive efficacy of individual tocopherols (α-, δ-, and γ-T) and a γ-T-rich tocopherol mixture (γ-TmT) in the August-Copenhagen Irish (ACI) rat model of estrogen-mediated mammary cancer. Female ACI rats receiving 17β-estradiol (E2) implants were administered with 0.2% α-T, δ-T, γ-T, or γ-TmT for 30 weeks. Although α-T had no significant effects on mammary tumor growth in ACI rats, δ-T, γ-T, and γ-TmT reduced mammary tumor volume by 51% (P < 0.05), 60% (P < 0.01), and 59% (P < 0.01), respectively. Immunohistochemical analysis revealed that δ-T, γ-T, and γ-TmT reduced levels of the cell proliferation marker, proliferating cell nuclear antigen, in the rat mammary tumors. To gain further insight into the biological functions of different forms of tocopherols, RNA-seq analysis of the tumors was performed. Treatment with γ-T induced robust gene expression changes in the mammary tumors of ACI rats. Ingenuity Pathway Analysis identified "Cancer" as a top disease pathway and "Tumor growth" and "Metastasis" as the top signaling pathways modulated by γ-T. Although the results need further functional validation, this study presents an unbiased attempt to understand the differences between biological activities of individual forms of tocopherols at the whole transcriptome level. In conclusion, δ-T and γ-T have superior cancer preventive properties compared to α-T in the prevention of estrogen-mediated mammary carcinogenesis. Cancer Prev Res; 10(12); 694-703. ©2017 AACR.

Vitamin D compounds inhibit cancer stem-like cells and induce differentiation in triple negative breast cancer

Triple-negative breast cancer is one of the least responsive breast cancer subtypes to available targeted therapies due to the absence of hormonal receptors, aggressive phenotypes, and the high rate of relapse. Early breast cancer prevention may therefore play an important role in delaying the progression of triple-negative breast cancer. Cancer stem cells are a subset of cancer cells that are thought to be responsible for tumor progression, treatment resistance, and metastasis. We have previously shown that vitamin D compounds, including a Gemini vitamin D analog BXL0124, suppress progression of ductal carcinoma in situ in vivo and inhibit cancer stem-like cells in MCF10DCIS mammosphere cultures. In the present study, the effects of vitamin D compounds in regulating breast cancer stem-like cells and differentiation in triple-negative breast cancer were assessed. Mammosphere cultures, which enriches for breast cancer cells with stem-like properties, were used to assess the effects of 1α,25(OH)₂D₃ and BXL0124 on cancer stem cell markers in the triple-negative breast cancer cell line, SUM159. Vitamin D compounds significantly reduced the mammosphere forming efficiency in primary, secondary and tertiary passages of mammospheres compared to control groups. Key markers of cancer stem-like phenotype and pluripotency were analyzed in mammospheres treated with 1α,25(OH)₂D₃ and BXL0124. As a result, OCT4, CD44 and LAMA5 levels were decreased. The vitamin D compounds also down-regulated the Notch signaling molecules, Notch1, Notch2, Notch3, JAG1, JAG2, HES1 and NFκB, which are involved in breast cancer stem cell maintenance. In addition, the vitamin D compounds up-regulated myoepithelial differentiating markers, cytokeratin 14 and smooth muscle actin, and down-regulated the luminal marker, cytokeratin 18. Cytokeratin 5, a biomarker associated with basal-like breast cancer, was found to be significantly down-regulated by the vitamin D compounds. These results suggest that vitamin D compounds may serve as potential preventive agents to inhibit triple negative breast cancer by regulating cancer stem cells and differentiation.

Structural analysis and biological activities of BXL0124, a gemini analog of vitamin D

Gemini analogs of calcitriol, characterized by the extension of the C21-methyl group of calcitriol with a second chain, act as agonists of the vitamin D receptor (VDR). This second side chain of gemini is accommodated in a new cavity inside the VDR created by the structural rearrangement of the protein core. The resulting conformational change preserves the active state of the receptor and bestows gemini compounds with biological activities that exceed those of calcitriol. Of particular interest are gemini's anti-cancer properties, and in this study we demonstrate anti-proliferative and tumor-reducing abilities of BXL0124 and BXL0097, differing only by the presence or absence, respectively, of the methylene group on the A ring. BXL0124 acts as a more potent VDR agonist than its 19-nor counterpart by activating VDR-mediated transcription at lower concentrations. In a similar manner, BXL0124 is more active than BXL0097 in growth inhibition of breast cancer cells and reduction of tumor volume. Structural comparisons of BXL0097 and BXL0124, as their VDR complexes, explain the elevated activity of the latter.

High concentration calcitriol induces endoplasmic reticulum stress related gene profile in breast cancer cells

Calcitriol, the active form of vitamin D, is known for its anticancer properties including induction of apoptosis as well as the inhibition of angiogenesis and metastasis. Understanding the mechanisms of action for calcitriol will help with the development of novel treatment strategies. Since vitamin D exerts its cellular actions via binding to its receptor and by altering expressions of a set of genes, we aimed to evaluate the effect of calcitriol on transcriptomic profile of breast cancer cells. We previously demonstrated that calcitriol alters endoplasmic reticulum (ER) stress markers, therefore in this study we have focused on ER-stress-related genes to reveal calcitriols action on these genes in particular. We have treated breast cancer cell lines MCF-7 and MDA-MB-231 with previously determined IC50 concentrations of calcitriol and evaluated the transcriptomic alterations via microarray. During analysis, only genes altered by at least 2-fold with a P value < 0.05 were taken into consideration. Our findings revealed an ER-stress-associated transcriptomic profile induced by calcitriol. Induced genes include genes with a pro-survival function (NUPR1, DNAJB9, HMOX1, LCN2, and LAMP3) and with a pro-death function (CHOP (DDIT3), DDIT4, NDGR1, NOXA, and CLGN). These results suggest that calcitriol induces an ER-stress-like response inducing both pro-survival and pro-death transcripts in the process.

Inhibitory Effects of γ- and δ-Tocopherols on Estrogen-Stimulated Breast Cancer In Vitro and In Vivo

Estrogens have been implicated as complete carcinogens for breast and other tissues through mechanisms involving increased cell proliferation, oxidative stress, and DNA damage. Because of their potent antioxidant activity and other effects, tocopherols have been shown to exert antitumor activities in various cancers. However, limited information is available on the effect of different forms of tocopherols in estrogen-mediated breast cancer. To address this, we examined the effects of α-, γ-, and δ-tocopherols as well as a natural γ-tocopherol-rich mixture of tocopherols, γ-TmT, on estrogen-stimulated MCF-7 cells in vitro and in vivo For the in vivo studies, MCF-7 cells were injected into the mammary fat pad of immunodeficient mice previously implanted with estrogen pellets. Mice were then administered diets containing 0.2% α-, γ-, δ-tocopherol, or γ-TmT for 5 weeks. Treatment with α-, γ-, δ-tocopherols, and γ-TmT reduced tumor volumes by 29% (P < 0.05), 45% (P < 0.05), 41% (P < 0.05), and 58% (P < 0.01), as well as tumor weights by 20%, 37% (P < 0.05), 39% (P < 0.05), and 52% (P < 0.05), respectively. γ- and δ-tocopherols and γ-TmT inhibited the expression of cell proliferation-related genes such as cyclin D1 and c-Myc, and estrogen-related genes such as TFF/pS2, cathepsin D, and progesterone receptor in estrogen-stimulated MCF-7 cells in vitro Further, γ- and δ-tocopherols decreased the levels of estrogen-induced oxidative stress and nitrosative stress markers, 8-hydroxy-2'-deoxyguanosine and nitrotyrosine, as well as the DNA damage marker, γ-H2AX. Our results suggest that γ- and δ-tocopherols and the γ-tocopherol-rich mixture are effective natural agents for the prevention and treatment of estrogen-mediated breast cancer. Cancer Prev Res; 10(3); 188-97. ©2017 AACR.

An improved methodology for the synthesis of 1α,25-dihydroxy-20-epi-vitamin D3 (MC 1288) and Gemini analog Ro-438-3582

Control over the C-20 stereochemistry allows a versatile method to introduce novel side-chains into the vitamin D scaffold.

Calcitriol stimulates gene expression of cathelicidin antimicrobial peptide in breast cancer cells with different phenotype

Background

In normal and neoplastic cells, growth-promoting, proangiogenic, cytotoxic and pro-apoptotic effects have all been attributed to cathelicidin antimicrobial peptide (CAMP). Nevertheless, little is known about the factors regulating this peptide expression in breast cancer. Herein we asked if the well-known antineoplastic hormone calcitriol could differentially modulate CAMP gene expression in human breast cancer cells depending on the cell phenotype in terms of efficacy and potency.

Methods

The established breast cancer cell lines MCF7, BT-474, HCC1806, HCC1937, SUM-229PE and a primary cell culture generated from invasive ductal breast carcinoma were used in this study. Calcitriol regulation of cathelicidin gene expression in vitro and in human breast cancer xenografts was studied by real time PCR. Tumorigenicity was evaluated for each cell line in athymic mice.

Results

Estrogen receptor (ER)α + breast cancer cells showed the highest basal CAMP gene expression. When incubated with calcitriol, CAMP gene expression was stimulated in a dose-dependent and cell phenotype-independent manner. Efficacy of calcitriol was lower in ERα + cells when compared to ERα- cells (<10 vs. >70 folds over control, respectively). Conversely, calcitriol lowest potency upon CAMP gene expression was observed in the ERα-/EGFR+ SUM-229PE cell line (EC₅₀ = 70.8 nM), while the highest was in the basal-type/triple-negative cells HCC1806 (EC₅₀ = 2.13 nM) followed by ERα + cells MCF7 and BT-474 (EC₅₀ = 4.42 nM and 14.6 nM, respectively). In vivo, lower basal CAMP gene expression was related to increased tumorigenicity and lack of ERα expression. Xenografted triple-negative breast tumors of calcitriol-treated mice showed increased CAMP gene expression compared to vehicle-treated animals.

Conclusions

Independently of the cell phenotype, calcitriol provoked a concentration-dependent stimulation on CAMP gene expression, showing greater potency in the triple negative HCC1806 cell line. Efficacy of calcitriol was lower in ERα + cells when compared to ERα- cells in terms of stimulating CAMP gene expression. Lower basal CAMP and lack of ERα gene expression was related to increased tumorigenicity. Our results suggest that calcitriol anti-cancer therapy is more likely to induce higher levels of CAMP in ERα- breast cancer cells, when compared to ERα + breast cancer cells.

Progestin-mediated activation of MAPK and AKT in nuclear progesterone receptor negative breast epithelial cells: The role of membrane progesterone receptors

Progesterone (P4), a steroid produced during estrous cycles and gestation for maintenance of pregnancy, also plays key roles in breast development to allow lactation post-parturition. Progestins (P4 and related steroids) are also implicated in breast cancer etiology. Hormone replacement therapy containing both estrogen and progestins increases breast cancer incidence while estrogen hormone therapy lowers breast cancer risk. P4 signaling via nuclear P4 receptors (PRs) has been extensively studied in breast cancer, however, progestin signaling via non-classical membrane bound progestin receptors (MPRs and PGRMC1) remains unclear. Moreover, P4 metabolites and synthetic progestins may bind membrane progestin receptors. We hypothesized that PR-negative breast epithelial cells express non-classical progestin receptors, which activate intracellular signaling pathways differently depending on nature of progestin. Therefore, our objectives for the current study were to determine expression of MPRs and PGRMC1 in two PR-negative non-tumorigenic breast epithelial cell lines, assess progestin-mediated signaling and biological functions. We determined five MPR isoforms and PGRMC1 were present in MCF10A cells and all progestin receptors but MPRβ in MCF12A cells. MCF10A and MCF12A cells were treated with P4, select P4 metabolites (5αP and 3αHP), medroxyprogesterone acetate (MPA), or a specific MPR-Agonist (MPR-Ag) and phosphorylation of ERK, p38, JNK, and AKT was characterized following treatment. To our knowledge this is the first report of ERK and JNK activation in MCF10A and MCF12A cells with P4, P4 metabolites, MPA, and MPR-Ag. Activation of ERK and JNK in cells treated with MPR-Ag implicates MPRs may serve as the receptors responsible for their activation. In contrast, p38 activation varied with cell type and with progestin treatment. P4 and MPA promoted AKT phosphorylation in the MCF12A cell line only whereas no activation was observed in MCF10A cells. Interestingly, cellular proliferation increased in MCF10A cells treated with MPA or 5αP, while MPR-Ag tended to slightly decrease proliferation. Collectively, our data highlights the importance of investigating the effects of synthetic progestins in breast cancer biology. Our results add to the understanding that various progestins have on breast epithelial cells and underscores the importance of considering both membrane bound receptors and progestin type in breast cancer development.

Tumoral Vitamin D Synthesis by CYP27B1 1-α-Hydroxylase Delays Mammary Tumor Progression in the PyMT-MMTV Mouse Model and Its Action Involves NF-κB Modulation

Biologically active vitamin D (1,25-dihydroxycholecalciferol or 1,25(OH)2D) is synthetized from inactive prohormone 25-hydroxycholecalciferol (25(OH)D) by the enzyme CYP27B1 1-α-hydroxylase in kidney and several extrarenal tissues including breast. Although the development of breast cancer has been linked to inadequate vitamin D status, the importance of bioactive vitamin D production within tumors themselves is not fully understood. To investigate the role of tumoral vitamin D production in mammary epithelial cell progression to breast cancer, we conducted a Cre-loxP-mediated Cyp27b1 gene ablation in the mammary epithelium of the polyoma middle T antigen-mouse mammary tumor virus (PyMT-MMTV) mouse breast cancer model. Targeted ablation of Cyp27b1 was accompanied by significant acceleration in initiation of spontaneous mammary tumorigenesis. In vivo, cell proliferation, angiogenesis, cell cycle progression, and survival markers were up-regulated in tumors by Cyp27b1 ablation, and apoptosis was decreased. AK thymoma (AKT) phosphorylation and expression of several components of nuclear factor κB (NF-κB), integrin, and signal transducer and activator of transcription 3 (STAT3) signaling pathways were increased in Cyp27b1-ablated tumors compared with nonablated controls. In vitro, 1,25(OH)2D treatment induced a strong antiproliferative action on tumor cells from both ablated and nonablated mice, accompanied by rapid disappearance of NF-κB p65 from the nucleus and segregation in the cytoplasm. In contrast, treatment with the metabolic precursor 25(OH)D was only effective against cells from nonablated mice. 25(OH)D did not inhibit growth of Cyp27b1-ablated cells, and their nuclear NF-κB p65 remained abundant. Our findings demonstrate that in-tumor CYP27B1 1-α-hydroxylase activity plays a crucial role in controlling early oncogene-mediated mammary carcinogenesis events, at least in part by modulating tumoral cell NF-κB p65 nuclear translocation.

The role of vitamin D in cancer prevention

Vitamin D, also known as cholecalciferol, is the precursor to the active steroid hormone 1, 25-dihydroxyvitamin D3 (calcitriol; 1, 25(OH)2D3). The main physiological role for 1, 25(OH)2D3 is to regulate calcium and inorganic phosphate homeostasis for bone health. More recently, vitamin D has been investigated for its effects in the prevention and treatment of a variety of diseases such as cancer, autoimmune disorders, and cardiovascular disease. Preclinical data strongly support a role for vitamin D in the prevention of cancer through its anti-proliferative, pro-apoptotic, and anti-angiogenic effects on cells. Epidemiologic and clinical studies have shown mixed data on the correlation between serum vitamin D levels and cancer risk. This report seeks to outline results from the most recent preclinical and clinical studies investigating the potential role of vitamin D in cancer prevention.

Gene Signatures of 1,25-Dihydroxyvitamin D3 Exposure in Normal and Transformed Mammary Cells

To elucidate potential mediators of vitamin D receptor (VDR) action in breast cancer, we profiled the genomic effects of its ligand 1,25-dihydroxyvitamin D3 (1,25D) in cells derived from normal mammary tissue and breast cancer. In non-transformed hTERT-HME cells, 483 1,25D responsive entities in 42 pathways were identified, whereas in MCF7 breast cancer cells, 249 1,25D responsive entities in 31 pathways were identified. Only 21 annotated genes were commonly altered by 1,25D in both MCF7 and hTERT-HME cells. Gene set enrichment analysis highlighted eight pathways (including senescence/autophagy, TGFβ signaling, endochondral ossification, and adipogenesis) commonly altered by 1,25D in hTERT-HME and MCF7 cells. Regulation of a subset of immune (CD14, IL1RL1, MALL, CAMP, SEMA6D, TREM1, CSF1, IL33, TLR4) and metabolic (ITGB3, SLC1A1, G6PD, GLUL, HIF1A, KDR, BIRC3) genes by 1,25D was confirmed in hTERT-HME cells and similar changes were observed in another comparable non-transformed mammary cell line (HME cells). The effects of 1,25D on these genes were retained in HME cells expressing SV40 large T antigen but were selectively abrogated in HME cells expressing SV40 + RAS and in MCF7 cells. Integration of the datasets from hTERT-HME and MCF7 cells with publically available RNA-SEQ data from 1,25D treated SKBR3 breast cancer cells enabled identification of an 11-gene signature representative of 1,25D exposure in all three breast-derived cell lines. Four of these 11 genes (CYP24A1, CLMN, EFTUD1, and SERPINB1) were also identified as 1,25D responsive in human breast tumor explants, suggesting that this gene signature may prove useful as a biomarker of vitamin D exposure in breast tissue.

Dietary γ-Tocopherol-Rich Mixture Inhibits Estrogen-Induced Mammary Tumorigenesis by Modulating Estrogen Metabolism, Antioxidant Response, and PPARγ

This study evaluated the anticancer activity and mechanism of action of a γ-tocopherol-rich tocopherol mixture, γ-TmT, in two different animal models of estrogen-induced breast cancer. The chemopreventive effect of γ-TmT at early (6 weeks), intermediate (18 weeks), and late (31 weeks) stages of mammary tumorigenesis was determined using the August-Copenhagen Irish rat model. Female rats receiving 17β-estradiol (E2) implants were administered with different doses (0%, 0.05%, 0.1%, 0.3%, and 0.5%) of γ-TmT diet. Treatment with 0.3% and 0.5% γ-TmT decreased tumor volume and multiplicity. At 31 weeks, serum concentrations of E2 were significantly decreased by γ-TmT. γ-TmT preferentially induced expression of the E2-metabolizing enzyme CYP1A1, over CYP1B1 in the rat mammary tissues. Nrf2-dependent antioxidant response was stimulated by γ-TmT, as evident from enhanced expression of its downstream targets, NQO1, GCLM, and HMOX1. Serum concentrations of the oxidative stress marker, 8-isoprostane, were also decreased in the γ-TmT-treated groups. Treatment with γ-TmT increased expression of PPARγ and its downstream genes, PTEN and p27, whereas the cell proliferation marker, PCNA, was significantly reduced in γ-TmT-treated mammary tumors. In an orthotopic model in which human MCF-7 breast cancer cells were injected into the mammary fat pad of immunodeficient mice, γ-TmT inhibited E2-dependent tumor growth at all the doses tested. In conclusion, γ-TmT reduced mammary tumor development, in part through decreased E2 availability and reduced oxidative stress in mammary tissues; γ-TmT could thus be an effective agent for the prevention and treatment of E2-induced breast cancer.

Vitamin D in cancer chemoprevention

CONTEXT

There is increasing evidence that Vitamin D (Vit D) and its metabolites, besides their well-known calcium-related functions, may also exert antiproliferative, pro-differentiating, and immune modulatory effects on tumor cells in vitro and may also delay tumor growth in vivo.

OBJECTIVE

The aim of this review is to provide fresh insight into the most recent advances on the role of Vit D and its analogues as chemopreventive drugs in cancer therapy.

METHODS

A systematic review of experimental and clinical studies on Vit D and cancer was undertaken by using the major electronic health database including ISI Web of Science, Medline, PubMed, Scopus and Google Scholar.

RESULTS AND CONCLUSION

Experimental and clinical observations suggest that Vit D and its analogues may be effective in preventing the malignant transformation and/or the progression of various types of human tumors including breast cancer, prostate cancer, colorectal cancer, and some hematological malignances. These findings suggest the possibility of the clinical use of these molecules as novel potential chemopreventive and anticancer agents.

Vitamin D compounds reduce mammosphere formation and decrease expression of putative stem cell markers in breast cancer

Breast cancer stem cells (BCSCs) are a subset of tumor cells that are believed to be the cells responsible for the establishment and maintenance of tumors. Moreover, BCSCs are suggested to be the main cause of progression to metastasis and recurrence of cancer because of their tumor-initiating abilities and resistance to conventional therapies. Ductal carcinoma in situ (DCIS) is an early precursor in breast carcinogenesis which progresses to invasive ductal carcinoma (IDC). We have previously reported that a vitamin D compound, BXL0124, inhibits the progression of DCIS to IDC. In the present study we sought to determine whether this effect was mediated through an influence on BCSCs. In MCF10DCIS cells treated with vitamin D compounds (1α25(OH)2D3 or BXL0124), the breast cancer stem cell-like population, identified by the CD44(+)/CD24(-/low) and CD49f(+)/CD24(-/low) subpopulations, was reduced. To determine the effects of vitamin D compounds on cancer stem cell activity, the MCF10DCIS mammosphere cell culture system, which enriches for mammary progenitor cells and putative BCSCs, was utilized. Untreated MCF10DCIS mammospheres showed a disorganized and irregular shape. When MCF10DCIS cells were treated with 1α25(OH)2D3 or BXL0124, the mammospheres that formed exhibited a more organized, symmetrical and circular shape, similar to the appearance of spheres formed by the non-malignant, normal mammary epithelial cell line, MCF10A. The mammosphere forming efficiency (MFE) was significantly decreased upon treatment with 1α25(OH)2D3 or BXL0124, indicating that these compounds have an inhibitory effect on mammosphere development. Treatment with 1α25(OH)2D3 or BXL0124 repressed markers associated with the stem cell-like phenotype, such as CD44, CD49f, c-Notch1, and pNFκB. Furthermore, 1α25(OH)2D3 and BXL0124 reduced the expression of pluripotency markers, OCT4 and KLF-4 in mammospheres. This study suggests that vitamin D compounds repress the breast cancer stem cell-like population, potentially contributing to their inhibition of breast cancer. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.

HES1-mediated inhibition of Notch1 signaling by a Gemini vitamin D analog leads to decreased CD44(+)/CD24(-/low) tumor-initiating subpopulation in basal-like breast cancer

Tumor-initiating cells (also known as cancer stem cells) are the subpopulation of cells shown to be responsible for tumor initiation, maintenance and recurrence. In breast cancer, CD44(+)/CD24(-/low) cells were identified as tumor-initiating cells. We previously reported that a Gemini vitamin D analog, 1,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol (BXL0124), reduced CD44(+)/CD24(-/low) cells in MCF10DCIS basal-like breast cancer cells. Since Notch has been identified as one of the key signaling pathways involved in breast cancer stem cells, the effect of BXL0124 on the Notch signaling pathway was investigated in breast cancer. The CD44(+)/CD24(-/low) subpopulation of MCF10DCIS cells showed elevated Notch1 signaling and increased cell proliferation compared to the CD44(+)/CD24(high) subpopulation. Treatment with the Gemini vitamin D analog BXL0124 decreased the level of activated Notch1 receptor. In addition, mRNA and protein levels of the Notch ligands, Jagged-1, Jagged-2 and DLL1, were significantly reduced by treatment with BXL0124, which was followed by repression of c-Myc, a key downstream target of Notch signaling. Interestingly, HES1, a known downstream target of Notch signaling, was rapidly induced by treatment with BXL0124. The inhibitory effect of BXL0124 on Notch signaling was reversed by knockdown of HES1. Overexpression of HES1 inhibited Notch1 signaling and reduced the CD44(+)/CD24(-/low) subpopulation, confirming a role of HES1 in Notch1 signaling. In conclusion, the Gemini vitamin D analog, BXL0124, represses the tumor-initiating subpopulation by HES1-mediated inhibition of Notch1 signaling. The present study demonstrates BXL0124 as a potent inhibitor of Notch signaling to target tumor-initiating cells in basal-like breast cancer. 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'.

Chemoprevention activity of 25-hydroxyvitamin D in the MMTV-PyMT mouse model of breast cancer

Development of oncologic conditions is often accompanied by inadequate vitamin D status. The chemoprevention ability of this molecule is of high interest for breast cancer, the most common malignancy in women worldwide. Because current effective vitamin D analogues, including the naturally occurring active metabolite 1,25-dihydroxycholecalciferol (1,25(OH)2D), frequently cause hypercalcemia at pharmacologic doses, the development of safer molecules for clinical chemopreventive use is essential. This study examines whether exogenously supplied prohormone 25-hydroxycholecalciferol (25(OH)D) can delay tumor progression in vivo without hypercalcemic effects. A low vitamin D diet (25 IU/kg) in the non-immunodeficient MMTV-PyMT mouse model of metastatic breast cancer revealed a significant acceleration of mammary neoplasia compared with normal diet (1,000 IU/kg). Systemic perfusion of MMTV-PyMT mice with 25(OH)D or 1,25(OH)2D delayed tumor appearance and significantly decreased lung metastasis, and both metabolites reduced Ki-67, cyclin D1, and ErbB2 levels in tumors. Perfusion with 25(OH)D caused a 50% raise in tumor 1,25(OH)2D levels, indicating good tumor penetration and effective activation. Importantly, in contrast with 1,25(OH)2D, perfusion with 25(OH)D did not cause hypercalcemia. In vitro treatment of cultured MMTV-PyMT mammary tumor cells with 25(OH)D inhibited proliferation, confirming local activation of the prohormone in this system. This study provides an in vivo demonstration in a non-immunodeficient model of spontaneous breast cancer that exogenous 25(OH)D delays neoplasia, tumor growth, and metastasis, and that its chemoprevention efficacy is not accompanied by hypercalcemia.

A synthetic triterpenoid CDDO-Im inhibits tumorsphere formation by regulating stem cell signaling pathways in triple-negative breast cancer

Triple-negative breast cancer is associated with poor prognosis because of a high rate of tumor recurrence and metastasis. Previous studies demonstrated that the synthetic triterpenoid, CDDO-Imidazolide (CDDO-Im) induced cell cycle arrest and apoptosis in triple-negative breast cancer. Since a small subpopulation of cancer stem cells has been suggested to be responsible for drug resistance and metastasis of tumors, our present study determined whether the effects of CDDO-Im in triple-negative breast cancer are due to the inhibition of a cancer stem cell subpopulation. CDDO-Im treatment markedly induced cell cycle arrest at G2/M-phase and apoptosis in the triple-negative breast cancer cell lines, SUM159 and MDA-MB-231. Because SUM159 cells were more sensitive to CDDO-Im than MDA-MB-231 cells, the effects of CDDO-Im on the cancer stem cell subpopulation were further investigated in SUM159 cells. SUM159 cells formed tumorspheres in culture, and the cancer stem cell subpopulation, CD24−/EpCAM+ cells, was markedly enriched in SUM159 tumorspheres. The CD24−/EpCAM+ cells in SUM159 tumorspheres were significantly inhibited by CDDO-Im treatment. CDDO-Im also significantly decreased sphere forming efficiency and tumorsphere size in both primary and secondary sphere cultures. PCR array of stem cell signaling genes showed that expression levels of many key molecules in the stem cell signaling pathways, such as Notch, TGF-β/Smad, Hedgehog and Wnt, were significantly down-regulated by CDDO-Im in SUM159 tumorspheres. Protein levels of Notch receptors (c-Notch1, Notch1 and Notch3), TGF-β/Smad (pSmad2/3) and Hedgehog downstream effectors (GLI1) also were markedly reduced by CDDO-Im. In conclusion, the present study demonstrates that the synthetic triterpenoid, CDDO-Im, is a potent anti-cancer agent against triple-negative breast cancer cells by targeting the cancer stem cell subpopulation.

The impact of vitamin D in breast cancer: genomics, pathways, metabolism

Nuclear receptors exert profound effects on mammary gland physiology and have complex roles in the etiology of breast cancer. In addition to receptors for classic steroid hormones such as estrogen and progesterone, the nuclear vitamin D receptor (VDR) interacts with its ligand 1α,25(OH)₂D₃ to modulate the normal mammary epithelial cell genome and subsequent phenotype. Observational studies suggest that vitamin D deficiency is common in breast cancer patients and that low vitamin D status enhances the risk for disease development or progression. Genomic profiling has characterized many 1α,25(OH)₂D₃ responsive targets in normal mammary cells and in breast cancers, providing insight into the molecular actions of 1α,25(OH)₂D₃ and the VDR in regulation of cell cycle, apoptosis, and differentiation. New areas of emphasis include regulation of tumor metabolism and innate immune responses. However, the role of VDR in individual cell types (i.e., epithelial, adipose, fibroblast, endothelial, immune) of normal and tumor tissues remains to be clarified. Furthermore, the mechanisms by which VDR integrates signaling between diverse cell types and controls soluble signals and paracrine pathways in the tissue/tumor microenvironment remain to be defined. Model systems of carcinogenesis have provided evidence that both VDR expression and 1α,25(OH)₂D₃ actions change with transformation but clinical data regarding vitamin D responsiveness of established tumors is limited and inconclusive. Because breast cancer is heterogeneous, analysis of VDR actions in specific molecular subtypes of the disease may help to clarify the conflicting data. The expanded use of genomic, proteomic and metabolomic approaches on a diverse array of in vitro and in vivo model systems is clearly warranted to comprehensively understand the network of vitamin D regulated pathways in the context of breast cancer.

The role of vitamin D in reducing cancer risk and progression

Vitamin D is not really a vitamin but the precursor to the potent steroid hormone calcitriol, which has widespread actions throughout the body. Calcitriol regulates numerous cellular pathways that could have a role in determining cancer risk and prognosis. Although epidemiological and early clinical trials are inconsistent, and randomized control trials in humans do not yet exist to conclusively support a beneficial role for vitamin D, accumulating results from preclinical and some clinical studies strongly suggest that vitamin D deficiency increases the risk of developing cancer and that avoiding deficiency and adding vitamin D supplements might be an economical and safe way to reduce cancer incidence and improve cancer prognosis and outcome.

Tocopherols inhibit oxidative and nitrosative stress in estrogen-induced early mammary hyperplasia in ACI rats

Oxidative stress is known to play a key role in estrogen-induced breast cancer. This study assessed the chemopreventive activity of the naturally occurring γ-tocopherol-rich mixture of tocopherols (γ-TmT) in early stages of estrogen-induced mammary hyperplasia in ACI rats. ACI rats provide an established model of rodent mammary carcinogenesis due to their high sensitivity to estrogen. Female rats were implanted with 9 mg of 17β-estradiol (E2) in silastic tubings and fed with control or 0.3% γ-TmT diet for 1, 3, 7, and 14 d. γ-TmT increased the levels of tocopherols and their metabolites in the serum and mammary glands of the rats. Histological analysis revealed mammary hyperplasia in the E2 treated rats fed with control or γ-TmT diet. γ-TmT decreased the levels of E2-induced nitrosative and oxidative stress markers, nitrotyrosine, and 8-oxo-dG, respectively, in the hyperplastic mammary tissues. 8-Isoprostane, a marker of oxidative stress in the serum, was also reduced by γ-TmT. Noticeably, γ-TmT stimulated Nrf2-dependent antioxidant response in the mammary glands of E2 treated rats, evident from the induced mRNA levels of Nrf2 and its downstream antioxidant enzymes, superoxide dismutase, catalase, and glutathione peroxidase. Therefore, inhibition of nitrosative/oxidative stress through induction of antioxidant response is the primary effect of γ-TmT in early stages of E2-induced mammary hyperplasia. Due to its cytoprotective activity, γ-TmT could be a potential natural agent for the chemoprevention of estrogen-induced breast cancer.

Inhibition of the transition of ductal carcinoma in situ to invasive ductal carcinoma by a Gemini vitamin D analog

Ductal carcinoma in situ (DCIS) is a nonmalignant lesion of the breast with the potential to progress to invasive ductal carcinoma (IDC). The disappearance and breakdown of the myoepithelial cell layer and basement membrane in DCIS have been identified as major events in the development of breast cancer. The MCF10DCIS.com cell line is a well-established model, which recapitulates the progression of breast cancer from DCIS to IDC. We have previously reported that a novel Gemini vitamin D analog, 1α,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol (BXL0124) is a potent inhibitor of the growth of MCF10DCIS.com xenografted tumors without hypercalcemic toxicity. In this study, we utilized the MCF10DCIS.com in vivo model to assess the effects of BXL0124 on breast cancer progression from weeks 1 to 4. Upon DCIS progression to IDC from weeks 3 to 4, tumors lost the myoepithelial cell layer and basement membrane as shown by immunofluorescence staining with smooth muscle actin and laminin 5, respectively. Administration of BXL0124 maintained the critical myoepithelial cell layer as well as basement membrane, and animals treated with BXL0124 showed a 43% reduction in tumor volume by week 4. BXL0124 treatment decreased cell proliferation and maintained vitamin D receptor levels in tumors. In addition, the BXL0124 treatment reduced the mRNA levels of matrix metalloproteinases starting at week 3, contributing to the inhibition of invasive transition. Our results suggest that the maintenance of DCIS plays a significant role in the cancer preventive action of the Gemini vitamin D BXL0124 during the progression of breast lesions.

Peroxisome proliferator-activated receptor and vitamin d receptor signaling pathways in cancer cells

Peroxisome proliferator-activated receptors (PPARs) are members of the superfamily of nuclear hormone receptors, which respond to specific ligands such as polyunsaturated fatty acids by altering gene expression. Three subtypes of this receptor have been discovered, each evolving to achieve different biological functions. Like other nuclear receptors, the transcriptional activity of PPARs is affected not only by ligand-stimulation, but also by cross-talk with other molecules. For example, both PPARs and the RXRs are ligand-activated transcription factors that coordinately regulate gene expression. In addition, PPARs and vitamin D receptor (VDR) signaling pathways regulate a multitude of genes that are of importance for cellular functions including cell proliferation and cell differentiation. Interaction of the PPARs and VDR signaling pathways has been shown at the level of molecular cross-regulation of their transcription factor. A variety of ligands influencing the PPARs and VDR signaling pathways have been shown to reveal chemopreventive potential by mediating tumor suppressive activities in human cancers. Use of these compounds may represent a potential novel strategy to prevent cancers. This review summarizes the roles of the PPARs and the VDR in pathogenesis and progression of cancer.

Molecular link between vitamin D and cancer prevention

The metabolite of vitamin D, 1α,25-dihydroxyvitamin D₃ (also known as calcitriol), is a biologically active molecule required to maintain the physiological functions of several target tissues in the human body from conception to adulthood. Its molecular mode of action ranges from immediate nongenomic responses to longer term mechanisms that exert persistent genomic effects. The genomic mechanisms of vitamin D action rely on cross talk between 1α,25-dihydroxyvitamin D₃ signaling pathways and that of other growth factors or hormones that collectively regulate cell proliferation, differentiation and cell survival. In vitro and in vivo studies demonstrate a role for vitamin D (calcitriol) in modulating cellular growth and development. Vitamin D (calcitriol) acts as an antiproliferative agent in many tissues and significantly slows malignant cellular growth. Moreover, epidemiological studies have suggested that ultraviolet-B exposure can help reduce cancer risk and prevalence, indicating a potential role for vitamin D as a feasible agent to prevent cancer incidence and recurrence. With the preventive potential of this biologically active agent, we suggest that countries where cancer is on the rise--yet where sunlight and, hence, vitamin D may be easily acquired--adopt awareness, education and implementation strategies to increase supplementation with vitamin D in all age groups as a preventive measure to reduce cancer risk and prevalence.

Oral administration of a gemini vitamin D analog, a synthetic triterpenoid and the combination prevents mammary tumorigenesis driven by ErbB2 overexpression

HER2 (or ErbB2), a member of ErbB receptor tyrosine kinases, is overexpressed in approximately 20% of human breast cancer, and the ErbB2 signaling pathway is a critical therapeutic target for ErbB2-overexpressing breast cancer. We investigated the inhibitory effects of the Gemini vitamin D analog BXL0124, the synthetic triterpenoid CDDO-Im and the combination on the tumorigenesis of ErbB2-overexpressing breast cancer. MMTV-ErbB2/neu transgenic mice were treated with BXL0124, CDDO-Im, or the combination from three months of age until the end of the experiment. Formation and growth of MMTV-ErbB2/neu mammary tumors were monitored every week, and all three treatments delayed the development of mammary tumors without significant toxicity. Decreased activation of ErbB2 as well as other ErbB receptors, ErbB1 and ErbB3, in MMTV-ErbB2/neu mammary tumors was shown by all treatments. Protein levels of downstream targets of the ErbB2 signaling pathway, including activated-Erk1/2, activated-Akt, c-Myc, CycD1, and Bcl2, were repressed by all three treatments, with the combination treatment exhibiting the strongest effects. To investigate therapeutic efficacy, the combination of BXL0124 and CDDO-Im was given to MMTV-ErbB2/neu mice after mammary tumors were established between 23 and 30 weeks of age. Short-term treatment with the combination did not show effects on tumor growth nor the ErbB2 signaling pathway. The present study shows BXL0124, CDDO-Im, and the combination as potential agents for prevention, but not treatment, against the tumorigenesis of ErbB2-overexpressing breast cancer.

Antineoplastic effects of 1,25(OH)2D3 and its analogs in breast, prostate and colorectal cancer

The active form of vitamin D3, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), is mostly known for its importance in the maintenance of calcium and phosphate homeostasis. However, next to its classical effects on bone, kidney and intestine, 1,25(OH)2D3 also exerts antineoplastic effects on various types of cancer. The use of 1,25(OH)2D3 itself as treatment against neoplasia is hampered by its calcemic side effects. Therefore, 1,25(OH)2D3-derived analogs were developed that are characterized by lower calcemic side effects and stronger antineoplastic effects. This review mainly focuses on the role of 1,25(OH)2D3 in breast, prostate and colorectal cancer (CRC) and the underlying signaling pathways. 1,25(OH)2D3 and its analogs inhibit proliferation, angiogenesis, migration/invasion and induce differentiation and apoptosis in malignant cell lines. Moreover, prostaglandin synthesis and Wnt/b-catenin signaling are also influenced by 1,25(OH)2D3 and its analogs. Human studies indicate an inverse association between serum 25(OH)D3 values and the incidence of certain cancer types. Given the literature, it appears that the epidemiological link between vitamin D3 and cancer is the strongest for CRC, however more intervention studies and randomized placebo-controlled trials are needed to unravel the beneficial dose of 1,25(OH)2D3 and its analogs to induce antineoplastic effects.

Transcriptional effects of 1,25 dihydroxyvitamin D(3) physiological and supra-physiological concentrations in breast cancer organotypic culture

BACKGROUND

Vitamin D transcriptional effects were linked to tumor growth control, however, the hormone targets were determined in cell cultures exposed to supra physiological concentrations of 1,25(OH)(2)D(3) (50-100nM). Our aim was to evaluate the transcriptional effects of 1,25(OH)(2)D(3) in a more physiological model of breast cancer, consisting of fresh tumor slices exposed to 1,25(OH)(2)D(3) at concentrations that can be attained in vivo.

METHODS

Tumor samples from post-menopausal breast cancer patients were sliced and cultured for 24 hours with or without 1,25(OH)(2)D(3) 0.5nM or 100nM. Gene expression was analyzed by microarray (SAM paired analysis, FDR≤0.1) or RT-qPCR (p≤0.05, Friedman/Wilcoxon test). Expression of candidate genes was then evaluated in mammary epithelial/breast cancer lineages and cancer associated fibroblasts (CAFs), exposed or not to 1,25(OH)(2)D(3) 0.5nM, using RT-qPCR, western blot or immunocytochemistry.

RESULTS

1,25(OH)(2)D(3) 0.5nM or 100nM effects were evaluated in five tumor samples by microarray and seven and 136 genes, respectively, were up-regulated. There was an enrichment of genes containing transcription factor binding sites for the vitamin D receptor (VDR) in samples exposed to 1,25(OH)(2)D(3) near physiological concentration. Genes up-modulated by both 1,25(OH)(2)D(3) concentrations were CYP24A1, DPP4, CA2, EFTUD1, TKTL1, KCNK3. Expression of candidate genes was subsequently evaluated in another 16 samples by RT-qPCR and up-regulation of CYP24A1, DPP4 and CA2 by 1,25(OH)(2)D(3) was confirmed. To evaluate whether the transcripitonal targets of 1,25(OH)(2)D(3) 0.5nM were restricted to the epithelial or stromal compartments, gene expression was examined in HB4A, C5.4, SKBR3, MDA-MB231, MCF-7 lineages and CAFs, using RT-qPCR. In epithelial cells, there was a clear induction of CYP24A1, CA2, CD14 and IL1RL1. In fibroblasts, in addition to CYP24A1 induction, there was a trend towards up-regulation of CA2, IL1RL1, and DPP4. A higher protein expression of CD14 in epithelial cells and CA2 and DPP4 in CAFs exposed to 1,25(OH)(2)D(3) 0.5nM was detected.

CONCLUSIONS

In breast cancer specimens a short period of 1,25(OH)(2)D(3) exposure at near physiological concentration modestly activates the hormone transcriptional pathway. Induction of CYP24A1, CA2, DPP4, IL1RL1 expression appears to reflect 1,25(OH)(2)D(3) effects in epithelial as well as stromal cells, however, induction of CD14 expression is likely restricted to the epithelial compartment.

Targeting CD44-STAT3 signaling by Gemini vitamin D analog leads to inhibition of invasion in basal-like breast cancer

Background

CD44, a transmembrane glycoprotein, is a major receptor for extracellular proteins involved in invasion and metastasis of human cancers. We have previously demonstrated that the novel Gemini vitamin D analog BXL0124 [1α,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluro-cholecalciferol] repressed CD44 expression in MCF10DCIS.com basal-like human breast cancer cells and inhibited MCF10DCIS xenograft tumor growth. In the present study, we investigated potential factors downstream of CD44 and the biological role of CD44 repression by BXL0124 in MCF10DCIS cells.

Methods and Findings

The treatment with Gemini vitamin D BXL0124 decreased CD44 protein level, suppressed STAT3 signaling, and inhibited invasion and proliferation of MCF10DCIS cells. The interaction between CD44 and STAT3 was determined by co-immunoprecipitation. CD44 forms a complex with STAT3 and Janus kinase 2 (JAK2) to activate STAT3 signaling, which was inhibited by BXL0124 in MCF10DCIS cells. The role of CD44 in STAT3 signaling and invasion of MCF10DCIS cells was further determined by the knockdown of CD44 using small hairpin RNA in vitro and in vivo. MCF10DCIS cell invasion was markedly decreased by the knockdown of CD44 in vitro. The knockdown of CD44 also significantly decreased mRNA expression levels of invasion markers, matrix metalloproteinases (MMPs) and urokinase plasminogen activator (uPA), in MCF10DCIS cells. In MCF10DCIS xenograft tumors, CD44 knockdown decreased tumor size and weight as well as invasion markers.

Conclusions

The present study identifies STAT3 as an important signaling molecule interacting with CD44 and demonstrates the essential role of CD44-STAT3 signaling in breast cancer invasion. It also suggests that repression of CD44-STAT3 signaling is a key molecular mechanism in the inhibition of breast cancer invasion by the Gemini vitamin D analog BXL0124.

Differences in transcriptional effects of 1α,25 dihydroxyvitamin D3 on fibroblasts associated to breast carcinomas and from paired normal breast tissues

The effects of 1α,25 dihydroxyvitamin D3 (1,25D) on breast carcinoma associated fibroblasts (CAFs) are still unknown. This study aimed to identify genes whose expression was altered after 1,25D treatment in CAFs and matched adjacent normal mammary associated fibroblasts (NAFs). CAFs and NAFs (from 5 patients) were cultured with or without (control) 1,25D 100 nM. Both CAF and NAF expressed vitamin D receptor (VDR) and 1,25D induction of the genomic pathway was detected through up-regulation of the target gene CYP24A1. Microarray analysis showed that despite presenting 50% of overlapping genes, CAFs and NAFs exhibited distinct transcriptional profiles after 1,25D treatment (FDR<0.05). Functional analysis revealed that in CAFs, genes associated with proliferation (NRG1, WNT5A, PDGFC) were down regulated and those involved in immune modulation (NFKBIA, TREM-1) were up regulated, consistent with anti tumor activities of 1,25D in breast cancer. In NAFs, a distinct subset of genes was induced by 1,25D, involved in anti apoptosis, detoxification, antibacterial defense system and protection against oxidative stress, which may limit carcinogenesis. Co-expression network and interactome analysis of genes commonly regulated by 1,25D in NAFs and CAFs revealed differences in their co-expression values, suggesting that 1,25D effects in NAFs are distinct from those triggered in CAFs.

Cellular and molecular effects of vitamin D on carcinogenesis

Epidemiologic data suggest that the incidence and severity of many types of cancer inversely correlates with indices of vitamin D status. The vitamin D receptor (VDR) is highly expressed in epithelial cells at risk for carcinogenesis including those resident in skin, breast, prostate and colon, providing a direct molecular link by which vitamin D status impacts on carcinogenesis. Consistent with this concept, activation of VDR by its ligand 1,25-dihydroxyvitamin D (1,25D) triggers comprehensive genomic changes in epithelial cells that contribute to maintenance of the differentiated phenotype, resistance to cellular stresses and protection of the genome. Many epithelial cells also express the vitamin D metabolizing enzyme CYP27B1 which enables autocrine generation of 1,25D from the circulating vitamin D metabolite 25-hydroxyvitamin D (25D), critically linking overall vitamin D status with cellular anti-tumor actions. Furthermore, pre-clinical studies in animal models has demonstrated that dietary supplementation with vitamin D or chronic treatment with VDR agonists decreases tumor development in skin, colon, prostate and breast. Conversely, deletion of the VDR gene in mice alters the balance between proliferation and apoptosis, increases oxidative DNA damage, and enhances susceptibility to carcinogenesis in these tissues. Because VDR expression is retained in many human tumors, vitamin D status may be an important modulator of cancer progression in persons living with cancer. Collectively, these observations have reinforced the need to further define the molecular actions of the VDR and the human requirement for vitamin D in relation to cancer development and progression.

Synthetic triterpenoids, CDDO-Imidazolide and CDDO-Ethyl amide, induce chondrogenesis

Novel methods for inducing chondrogenesis are critical for cartilage tissue engineering and regeneration. Here we show that the synthetic oleanane triterpenoids, CDDO-Imidazolide (CDDO-Im) and CDDO-Ethyl amide (CDDO-EA), at concentrations as low as 200 nM, induce chondrogenesis in organ cultures of newborn mouse calvaria. The cartilage phenotype was measured histologically with metachromatic toluidine blue staining for proteoglycans and by immunohistochemical staining for type II collagen. Furthermore, real-time polymerase chain reaction (PCR) analysis using mRNA from calvaria after 7-day treatment with CDDO-Im and CDDO-EA showed up-regulation of the chondrocyte markers SOX9 and type II collagen (alpha1). In addition, TGF-β; BMPs 2 and 4; Smads 3, 4, 6, and 7; and TIMPs-1 and -2 were increased. In contrast, MMP-9 was strongly down-regulated. Treatment of human bone marrow-derived mesenchymal stem cells with CDDO-Im and CDDO-EA (100 nM) induced expression of SOX9, collagen IIα1, and aggrecan, as well as BMP-2 and phospho-Smad5, confirming that the above triterpenoids induce chondrogenic differentiation. This is the first report of the use of these drugs for induction of chondrogenesis.

Dietary tocopherols inhibit cell proliferation, regulate expression of ERα, PPARγ, and Nrf2, and decrease serum inflammatory markers during the development of mammary hyperplasia

Previous clinical and epidemiological studies of vitamin E have used primarily α-tocopherol for the prevention of cancer. However, γ-tocopherol has demonstrated greater anti-inflammatory and anti-tumor activity than α-tocopherol in several animal models of cancer. This study assessed the potential chemopreventive activities of a tocopherol mixture containing 58% γ-tocopherol (γ-TmT) in an established rodent model of mammary carcinogenesis. Female ACI rats were utilized due to their sensitivity to 17β-estradiol (E2 ) to induce mammary hyperplasia and neoplasia. The rats were implanted subcutaneously with sustained release E2 pellets and given dietary 0.3% or 0.5% γ-TmT for 2 or 10 wk. Serum E2 levels were significantly reduced by the treatment with 0.5% γ-TmT. Serum levels of inflammatory markers, prostaglandin E2 and 8-isoprostane, were suppressed by γ-TmT treatment. Histology of mammary glands showed evidence of epithelial hyperplasia in E2 -treated rats. Immunohistochemical analysis of the mammary glands revealed a decrease in proliferating cell nuclear antigen (PCNA), cyclooxygenase-2 (COX-2), and estrogen receptor α (ERα), while there was an increase in cleaved-caspase 3, peroxisome proliferator-activated receptor γ (PPARγ), and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in γ-TmT-treated rats. In addition, treatment with γ-TmT resulted in a decrease in the expression of ERα mRNA, whereas mRNA levels of ERβ and PPARγ were increased. In conclusion, γ-TmT was shown to suppress inflammatory markers, inhibit E2 -induced cell proliferation, and upregulate PPARγ and Nrf2 expression in mammary hyperplasia, suggesting that γ-TmT may be a promising agent for human breast cancer prevention.

Vitamin D and cancer: a review of molecular mechanisms

The population-based association between low vitamin D status and increased cancer risk can be inconsistent, but it is now generally accepted. These relationships link low serum 25OHD (25-hydroxyvitamin D) levels to cancer, whereas cell-based studies show that the metabolite 1,25(OH)2D (1,25-dihydroxyvitamin D) is a biologically active metabolite that works through vitamin D receptor to regulate gene transcription. In the present review we discuss the literature relevant to the molecular events that may account for the beneficial impact of vitamin D on cancer prevention or treatment. These data show that although vitamin D-induced growth arrest and apoptosis of tumour cells or their non-neoplastic progenitors are plausible mechanisms, other chemoprotective mechanisms are also worthy of consideration. These alternative mechanisms include enhancing DNA repair, antioxidant protection and immunomodulation. In addition, other cell targets, such as the stromal cells, endothelial cells and cells of the immune system, may be regulated by 1,25(OH)2D and contribute to vitamin D-mediated cancer prevention.

20-Hydroxyvitamin D2 is a noncalcemic analog of vitamin D with potent antiproliferative and prodifferentiation activities in normal and malignant cells

20-hydroxyvitamin D(2) [20(OH)D(2)] inhibits DNA synthesis in epidermal keratinocytes, melanocytes, and melanoma cells in a dose- and time-dependent manner. This inhibition is dependent on cell type, with keratinocytes and melanoma cells being more sensitive than normal melanocytes. The antiproliferative activity of 20(OH)D(2) is similar to that of 1,25(OH)(2)D(3) and of newly synthesized 1,20(OH)(2)D(2) but significantly higher than that of 25(OH)D(3). 20(OH)D(2) also displays tumorostatic effects. In keratinocytes 20(OH)D(2) inhibits expression of cyclins and stimulates involucrin expression. It also stimulates CYP24 expression, however, to a significantly lower degree than that by 1,25(OH)(2)D(3) or 25(OH)D(3). 20(OH)D(2) is a poor substrate for CYP27B1 with overall catalytic efficiency being 24- and 41-fold lower than for 25(OH)D(3) with the mouse and human enzymes, respectively. No conversion of 20(OH)D(2) to 1,20(OH)(2)D(2) was detected in intact HaCaT keratinocytes. 20(OH)D(2) also demonstrates anti-leukemic activity but with lower potency than 1,25(OH)(2)D(3). The phenotypic effects of 20(OH)D(2) are mediated through interaction with the vitamin D receptor (VDR) as documented by attenuation of cell proliferation after silencing of VDR, by enhancement of the inhibitory effect through stable overexpression of VDR and by the demonstration that 20(OH)D(2) induces time-dependent translocation of VDR from the cytoplasm to the nucleus at a comparable rate to that for 1,25(OH)(2)D(3). In vivo tests show that while 1,25(OH)(2)D(3) at doses as low as 0.8 μg/kg induces calcium deposits in the kidney and heart, 20(OH)D(2) is devoid of such activity even at doses as high as 4 μg/kg. Silencing of CY27B1 in human keratinocytes showed that 20(OH)D(2) does not require its transformation to 1,20(OH)(2)D(2) for its biological activity. Thus 20(OH)D(2) shows cell-type dependent antiproliferative and prodifferentiation activities through activation of VDR, while having no detectable toxic calcemic activity, and is a poor substrate for CYP27B1.

A novel Gemini vitamin D analog represses the expression of a stem cell marker CD44 in breast cancer

CD44 is a multifunctional transmembrane protein involved in cell proliferation, angiogenesis, invasion, and metastasis. CD44 is identified as a cancer stem cell marker, and the CD44-positive breast cancer cells are enriched in residual breast cancer cell populations after conventional therapies, suggesting that CD44 may be an important target for cancer prevention and therapy. Therefore, we investigated for the inhibitory effect of a novel Gemini vitamin D analog, 1α,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol (BXL0124), on mammary tumor growth and CD44 expression in MCF10DCIS.com human breast cancer in vitro and in vivo. MCF10DCIS.com cells were injected into mammary fat pads in immunodeficient mice, and BXL0124 was then administered intraperitoneally (0.1 μg/kg body weight) or orally (0.03 or 0.1 μg/kg body weight) 6 days a week for 5 weeks. At necropsy, mammary tumors and blood were collected for evaluating tumor growth, CD44 expression, and serum calcium level. BXL0124 suppressed mammary tumor growth and markedly decreased the expression of CD44 protein in MCF10DCIS xenograft tumors without causing hypercalcemic toxicity. BXL0124 also inhibited the expression of CD44 protein and mRNA as well as the transcriptional activity of the CD44 promoter in cultured MCF10DCIS.com cells. The repression of CD44 expression induced by BXL0124 was blocked by siRNA vitamin D receptor (VDR), indicating that the regulation of CD44 expression by BXL0124 is a VDR-dependent event. The novel Gemini vitamin D analog, BXL0124, represses CD44 expression in MCF10DCIS.com cells in vitro and in xenograft tumors, suggesting an inhibitory role of a Gemini vitamin D derivative on breast cancer stem cells.

Gemini vitamin D analog suppresses ErbB2-positive mammary tumor growth via inhibition of ErbB2/AKT/ERK signaling

Numerous synthetic vitamin D analogs have been studied for their effects on the prevention and treatment of breast cancer. However, the inhibitory effects of naturally occurring 1alpha,25-dihydroxyvitamin D3 or its synthetic analogs on ErbB2 overexpressing mammary tumorigenesis have not been reported. Gemini vitamin D analogs are novel synthetic vitamin D derivatives with a unique structure of two six-carbon chains at C-20. We have previously shown that Gemini vitamin D analogs significantly inhibited carcinogen-induced estrogen receptor (ER)-positive mammary tumorigenesis and reduced ER-negative MCF10DCIS.com xenograft tumor growth without hypercalcemic toxicity. In the present study, we have determined the inhibitory effect of a potent Gemini vitamin D analog BXL0124 (1alpha,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol) on the ErbB2/Her-2/neu overexpressing mammary tumorigenesis. The Gemini BXL0124 inhibits ErbB2-positive mammary tumor growth and down-regulates the phosphorylation of ErbB2, ERK and AKT in tumors of MMTV-ErbB2/neu transgenic mice. These effects of Gemini BXL0124 in vivo were confirmed by using the ErbB2 overexpressing tumor cells derived from the mammary tumors of MMTV-ErbB2/neu mice. In conclusion, the Gemini vitamin D analog BXL0124 inhibits the growth of ErbB2 overexpressing mammary tumors through regulating the ErbB2/AKT/ERK signaling pathways, suggesting that Gemini vitamin D analog may be considered for translational studies.

Genomic vitamin D signaling in breast cancer: Insights from animal models and human cells

These studies focus on identification of vitamin D regulated pathways that impact development or progression of breast cancer. In mouse experiments, we assessed genomic profiles of glandular tissue and established tumors from MMTV-neu mice fed adequate (250 IU/kg) or high (5000 IU/kg) vitamin D (cholecalciferol). Genomic profiles were also obtained in murine mammary cells that differentially express VDR that were cultured in vitro with 100 nM 1,25-dihydroxyvitamin D (1,25D). Ten candidate genes were identified that were commonly regulated in murine cells treated with 1,25D in vitro and in mammary gland of mice fed high dietary vitamin D. In complementary studies, the vitamin D pathway was evaluated in human mammary epithelial cells as a function of transformation. Genes regulated by 1,25D in human mammary epithelial cells included those involved in innate immunity (CD14), differentiation (Bmp6), extracellular matrix remodeling (Plau) and cell survival (Birc3). Transformation reduced VDR content and blunted the induction of some, but not all, target genes by 1,25D in human mammary cells. Collectively, these in vivo and in vitro data demonstrate that vitamin D signaling impacts on common pathways that drive differentiation, alter metabolism, remodel the extracellular matrix and trigger innate immunity in mammary tissue.

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.

Mixed tocopherols prevent mammary tumorigenesis by inhibiting estrogen action and activating PPAR-gamma

PURPOSE

Tocopherols are lipophilic antioxidants present in vegetable oils. Although the antioxidant and anticancer activities of alpha-tocopherol (vitamin E) have been studied for decades, recent intervention studies with alpha-tocopherol have been negative for protection from cancer in humans. The tocopherols consist of four isoforms, which are the alpha, beta, gamma, and delta variants, and recent attention is being given to other isoforms. In the present study, we investigated the inhibitory effect of a tocopherol mixture rich in gamma- and delta-tocopherols against mammary tumorigenesis.

EXPERIMENTAL DESIGN

Female Sprague Dawley rats were treated with N-methyl-N-nitrosourea (NMU), and then fed diets containing 0.1%, 0.3%, or 0.5% mixed tocopherols rich in gamma- and delta-tocopherols for 9 weeks. Tumor burden and multiplicity were determined, and the levels of markers of inflammation, proliferation, and apoptosis were evaluated in the serum and in mammary tumors. The regulation of nuclear receptor signaling by tocopherols was studied in mammary tumors and in breast cancer cells.

RESULTS

Dietary administration of 0.1%, 0.3%, or 0.5% mixed tocopherols suppressed mammary tumor growth by 38%, 50%, or 80%, respectively. Tumor multiplicity was also significantly reduced in all three mixed tocopherol groups. Mixed tocopherols increased the expression of p21, p27, caspase-3, and peroxisome proliferator activated receptor-gamma, and inhibited AKT and estrogen signaling in mammary tumors. Our mechanistic study found that gamma- and delta-tocopherols, but not alpha-tocopherol, activated peroxisome proliferator activated receptor-gamma and antagonized estrogen action in breast cancer.

CONCLUSION

The results suggest that gamma- and delta-tocopherols may be effective agents for the prevention of breast cancer.

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.