Chondro/osteoblastic and cardiovascular gene modulation in human artery smooth muscle cells that calcify in the presence of phosphate and calcitriol or paricalcitol

Pathological mutations reveal the key role of the cytosolic iRhom2 N-terminus for phosphorylation-independent 14-3-3 interaction and ADAM17 binding, stability, and activity

The protease ADAM17 plays an important role in inflammation and cancer and is regulated by iRhom2. Mutations in the cytosolic N-terminus of human iRhom2 cause tylosis with oesophageal cancer (TOC). In mice, partial deletion of the N-terminus results in a curly hair phenotype (cub). These pathological consequences are consistent with our findings that iRhom2 is highly expressed in keratinocytes and in oesophageal cancer. Cub and TOC are associated with hyperactivation of ADAM17-dependent EGFR signalling. However, the underlying molecular mechanisms are not understood. We have identified a non-canonical, phosphorylation-independent 14-3-3 interaction site that encompasses all known TOC mutations. Disruption of this site dysregulates ADAM17 activity. The larger cub deletion also includes the TOC site and thus also dysregulated ADAM17 activity. The cub deletion, but not the TOC mutation, also causes severe reductions in stimulated shedding, binding, and stability of ADAM17, demonstrating the presence of additional regulatory sites in the N-terminus of iRhom2. Overall, this study contrasts the TOC and cub mutations, illustrates their different molecular consequences, and reveals important key functions of the iRhom2 N-terminus in regulating ADAM17.

Restoration of Vitamin D Levels Improves Endothelial Function and Increases TASK-Like K+ Currents in Pulmonary Arterial Hypertension Associated with Vitamin D Deficiency

Background: Vitamin D (vitD) deficiency is highly prevalent in patients with pulmonary arterial hypertension (PAH). Moreover, PAH-patients with lower levels of vitD have worse prognosis. We hypothesize that recovering optimal levels of vitD in an animal model of PAH previously depleted of vitD improves the hemodynamics, the endothelial dysfunction and the ionic remodeling. Methods: Male Wistar rats were fed a vitD-free diet for five weeks and then received a single dose of Su5416 (20 mg/Kg) and were exposed to vitD-free diet and chronic hypoxia (10% O₂) for three weeks to induce PAH. Following this, vitD deficient rats with PAH were housed in room air and randomly divided into two groups: (a) continued on vitD-free diet or (b) received an oral dose of 100,000 IU/Kg of vitD plus standard diet for three weeks. Hemodynamics, pulmonary vascular remodeling, pulmonary arterial contractility, and K⁺ currents were analyzed. Results: Recovering optimal levels of vitD improved endothelial function, measured by an increase in the endothelium-dependent vasodilator response to acetylcholine. It also increased the activity of TASK-1 potassium channels. However, vitD supplementation did not reduce pulmonary pressure and did not ameliorate pulmonary vascular remodeling and right ventricle hypertrophy. Conclusions: Altogether, these data suggest that in animals with PAH and severe deficit of vitD, restoring vitD levels to an optimal range partially improves some pathophysiological features of PAH.

Potassium (K+) channels in the pulmonary vasculature: Implications in pulmonary hypertension Physiological, pathophysiological and pharmacological regulation

The large K⁺ channel functional diversity in the pulmonary vasculature results from the multitude of genes expressed encoding K⁺ channels, alternative RNA splicing, the post-transcriptional modifications, the presence of homomeric or heteromeric assemblies of the pore-forming α-subunits and the existence of accessory β-subunits modulating the functional properties of the channel. K⁺ channels can also be regulated at multiple levels by different factors controlling channel activity, trafficking, recycling and degradation. The activity of these channels is the primary determinant of membrane potential (Em) in pulmonary artery smooth muscle cells (PASMC), providing an essential regulatory mechanism to dilate or contract pulmonary arteries (PA). K⁺ channels are also expressed in pulmonary artery endothelial cells (PAEC) where they control resting Em, Ca²⁺ entry and the production of different vasoactive factors. The activity of K⁺ channels is also important in regulating the population and phenotype of PASMC in the pulmonary vasculature, since they are involved in cell apoptosis, survival and proliferation. Notably, K⁺ channels play a major role in the development of pulmonary hypertension (PH). Impaired K⁺ channel activity in PH results from: 1) loss of function mutations, 2) downregulation of its expression, which involves transcription factors and microRNAs, or 3) decreased channel current as a result of increased vasoactive factors (e.g., hypoxia, 5-HT, endothelin-1 or thromboxane), exposure to drugs with channel-blocking properties, or by a reduction in factors that positively regulate K⁺ channel activity (e.g., NO and prostacyclin). Restoring K⁺ channel expression, its intracellular trafficking and the channel activity is an attractive therapeutic strategy in PH.

Vitamin D deficiency downregulates TASK-1 channels and induces pulmonary vascular dysfunction

Vitamin D (VitD) receptor regulates the expression of several genes involved in signaling pathways affected in pulmonary hypertension (PH). VitD deficiency is highly prevalent in PH, and low levels are associated with poor prognosis. We investigated if VitD deficiency may predispose to or exacerbate PH. Male Wistar rats were fed with a standard or a VitD-free diet for 5 wk. Next, rats were further divided into controls or PH, which was induced by a single dose of Su-5416 (20 mg/kg) and exposure to hypoxia (10% O2) for 2 wk. VitD deficiency had no effect on pulmonary pressure in normoxic rats, indicating that, by itself, it does not trigger PH. However, it induced several moderate but significant changes characteristic of PH in the pulmonary arteries, such as increased muscularization, endothelial dysfunction, increased survivin, and reduced bone morphogenetic protein ( Bmp) 4, Bmp6, DNA damage-inducible transcript 4, and K+ two - pore domain channel subfamily K member 3 ( Kcnk3) expression. Myocytes isolated from pulmonary arteries from VitD-deficient rats had a reduced whole voltage-dependent potassium current density and acid-sensitive (TASK-like) potassium currents. In rats with PH induced by Su-5416 plus hypoxia, VitD-free diet induced a modest increase in pulmonary pressure, worsened endothelial function, increased the hyperreactivity to serotonin, arterial muscularization, decreased total and TASK-1 potassium currents, and further depolarized the pulmonary artery smooth muscle cell membrane. In human pulmonary artery smooth muscle cells from controls and patients with PH, the active form of VitD calcitriol significantly increased KCNK3 mRNA expression. Altogether, these data strongly suggest that the deficit in VitD induces pulmonary vascular dysfunction.

Reactive oxygen species (ROS) generation as an underlying mechanism of inorganic phosphate (Pi)-induced mineralization of osteogenic cells

Reactive Oxygen Species (ROS) are a natural byproduct of oxygen metabolism. At physiological levels, ROS regulate multiple cellular processes like proliferation, migration, and differentiation. Increased levels of ROS are associated with pathological conditions, such as inflammation and vascular calcification, where they elicit cytotoxic effects. These contrasting outcomes of ROS have also been reported in osteogenic precursor cells. However, the role of ROS in committed osteogenic cells has not been investigated. Cytotoxic and physiologic effects have also been demonstrated for extracellular phosphate (Pi). Specifically, in committed osteogenic cells Pi stimulates their major function (mineralization), however in osteogenic precursors and endothelial cells Pi cytotoxicity has been reported. Interestingly, Pi cytotoxic effects have been associated with ROS production in the pathological vascular mineralization. In this study, we investigated a molecular mechanistic link between elevated Pi and ROS production in the context of the mineralization function of committed osteogenic cells. Using committed osteogenic cells, 17IIA11 odontoblast-like cell and MLO-A5 osteoblast cell lines, we have unveil that Pi enhances intracellular ROS production. Furthermore, using a combination of mineralization assays and gene expression analyses, we determined that Pi-induced intracellular ROS supports the physiological mineralization process. In contrast, the exogenous ROS, provided in a form of H2O2, was detrimental for osteogenic cells. By comparing molecular signaling cascades induced by extracellular ROS and Pi, we identified differences in signaling routes that determine physiologic versus toxic effect of ROS on osteogenic cells. Specifically, while both extracellular and Pi-induced intracellular ROS utilize Erk1/2 signaling mediator, only extracellular ROS induces stress-activated mitogen-activated protein kinases P38 and JNK that are associated with cell death. In summary, our results uncovered a physiological role of ROS in the Pi-induced mineralization through the molecular pathway that is distinct from ROS-induced cytotoxic effects.

Captopril Attenuates the Upregulated Connexin 43 Expression in Artery Calcification

OBJECTIVE

Vascular calcification is commonly observed in atherosclerosis and diabetes. The renin-angiotensin II system is associated with the regulation of arterial stiffening. The aim of this study was to examine whether the angiotensin-converting enzyme inhibitors captopril attenuates artery calcification.

METHODS

The rat model of arterial calcification was established by a combination of warfarin and vitamin K1. Two weeks after the induction of arterial calcification, captopril treatment was initiated. One week after captopril treatment, aortic arteries were examined to determine the calcification morphology and the connexin 43 expression. Matrix Gla protein (MGP), receptor activator of nuclear factor-κB ligand (RANKL) and extracellular regulated protein kinase (ERK) pathways were examined.

RESULTS

The morphology of the calcified arteries was significantly attenuated after captopril treatment. Consistently, captopril inhibited the increased connexin 43 expression and enhanced the decreased MGP expression in calcification arteries. Furthermore, captopril enhanced the decreased SM22 expression in calcified arteries by fluorescence assay. Finally, the calcification arteries increased the p38, p-ERK and RANKL expression, which were downregulated by captopril treatment.

CONCLUSIONS

We concluded that captopril attenuated the increased connexin 43 expression and enhanced the MGP and SM22 expression levels, which are associated with the inactivation of p-ERK, p38 and RANKL pathways in rat aortic arteries.

Agonists and knockdown of estrogen receptor β differentially affect invasion of triple-negative breast cancer cells in vitro

Background

Estrogen receptor β (ERβ) is expressed in the majority of invasive breast cancer cases, irrespective of their subtype, including triple-negative breast cancer (TNBC). Thus, ERβ might be a potential target for therapy of this challenging cancer type. In this in vitro study, we examined the role of ERβ in invasion of two triple-negative breast cancer cell lines.

Methods

MDA-MB-231 and HS578T breast cancer cells were treated with the specific ERβ agonists ERB-041, WAY200070, Liquiritigenin and 3β-Adiol. Knockdown of ERβ expression was performed by means of siRNA transfection. Effects on cellular invasion were assessed in vitro by means of a modified Boyden chamber assay. Transcriptome analyses were performed using Affymetrix Human Gene 1.0 ST microarrays. Pathway and gene network analyses were performed by means of Genomatix and Ingenuity Pathway Analysis software.

Results

Invasiveness of MBA-MB-231 and HS578T breast cancer cells decreased after treatment with ERβ agonists ERB-041 and WAY200070. Agonists Liquiritigenin and 3β-Adiol only reduced invasion of MDA-MB-231 cells. Knockdown of ERβ expression increased invasiveness of MDA-MB-231 cells about 3-fold. Transcriptome and pathway analyses revealed that ERβ knockdown led to activation of TGFβ signalling and induced expression of a network of genes with functions in extracellular matrix, tumor cell invasion and vitamin D3 metabolism.

Conclusions

Our data suggest that ERβ suppresses invasiveness of triple-negative breast cancer cells in vitro. Whether ERβ agonists might be useful drugs in the treatment of triple-negative breast cancer, has to be evaluated in further animal and clinical studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2973-y) contains supplementary material, which is available to authorized users.

Systems biological understanding of the regulatory network and the possible therapeutic strategies for vascular calcification

Since there is no precise therapy for treating vascular calcification by directly targeting the vascular wall, we aim to unveil novel drug targets through mining the molecular effect of a high phosphate environment on vascular cells through computational methods. Here, we hypothesize that manipulation of the vascular pathogenic network by small molecule therapeutics predicted from prior knowledge might offer great promise. With this, we intend to understand the publicly available transcriptomic data of vascular smooth muscle cells and endothelial cells exposed to the high phosphate induced vascular calcification milieu and to re-examine the above published experiments for reasons different from those examined in the previous studies through multilevel systems biological understanding. Hence, in this study the differentially expressed genes were subjected to both upstream and downstream network analysis through multiple standalone software and web servers. To provide an insight into causal signaling, we simultaneously predicted upstream regulatory layers through transcription factor and kinome enrichment analysis. Moreover the possible systems pharmacological choices were presented in three ways as (1) drug induced expression modulation, (2) drugs that interact with upstream and downstream regulatory targets, (3) possible natural product therapeutics from target-compound relationship. Furthermore for validating the current study we have specifically evaluated the preventive effect of two predicted natural compounds in a bovine aortic calcification model. The overall observation predicts a few novel mechanisms that might be involved in vascular dysfunction and calcification in both cell types. Also, the systems pharmacological investigation provides clues for the possible therapeutic options along with validation. In conclusion, the current study indicates that reanalysis of transcriptomic data propels us to reposition the approved drugs and use natural compounds as novel therapeutic agents for vascular calcification.

Induction of DKK1 by ox-LDL negatively regulates intracellular lipid accumulation in macrophages

Dickkopf1 (DKK1), a canonical Wnt/β-catenin pathway antagonist, is closely associated with cardiovascular disease and adipogenesis. We performed an in vitro study to determine whether oxidized low-density lipoprotein (ox-LDL) increased the expression of DKK1 in macrophages and whether β-catenin and liver X receptor α (LXRα) were involved in this regulation. Induction of DKK1 expression by ox-LDL decreased the level of lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) via a Wnt/β-catenin pathway and increased ATP-binding cassette transporter A/G1 (ABCA/G1) levels via a signal transducer and activator of transcription 3 (STAT3) pathway. Lower LOX-1 and higher ABCA/G1 levels inhibited cholesterol loading in macrophages. In conclusion, ox-LDL may induce DKK1 expression in macrophages to inhibit the accumulation of lipids through a mechanism that involves downregulation of LOX-1-mediated lipid uptake and upregulation of ABCA/G1-dependent cholesterol efflux.

The future of vitamin D analogs

The active form of vitamin D₃, 1,25-dihydroxyvitamin D₃, is a major regulator of bone and calcium homeostasis. In addition, this hormone also inhibits the proliferation and stimulates the differentiation of normal as well as malignant cells. Supraphysiological doses of 1,25-dihydroxyvitamin D₃ are required to reduce cancer cell proliferation. However, these doses will lead in vivo to calcemic side effects such as hypercalcemia and hypercalciuria. During the last 25 years, many structural analogs of 1,25-dihydroxyvitamin D₃ have been synthesized by the introduction of chemical modifications in the A-ring, central CD-ring region or side chain of 1,25-dihydroxyvitamin D₃ in the hope to find molecules with a clear dissociation between the beneficial antiproliferative effects and adverse calcemic side effects. One example of such an analog with a good dissociation ratio is calcipotriol (Daivonex®), which is clinically used to treat the hyperproliferative skin disease psoriasis. Other vitamin D analogs were clinically approved for the treatment of osteoporosis or secondary hyperparathyroidism. No vitamin D analog is currently used in the clinic for the treatment of cancer although several analogs have been shown to be potent drugs in animal models of cancer. Transcriptomics studies as well as in vitro cell biological experiments unraveled basic mechanisms involved in the antineoplastic effects of vitamin D and its analogs. 1,25-dihydroxyvitamin D₃ and analogs act in a cell type- and tissue-specific manner. Moreover, a blockade in the transition of the G0/1 toward S phase of the cell cycle, induction of apoptosis, inhibition of migration and invasion of tumor cells together with effects on angiogenesis and inflammation have been implicated in the pleiotropic effects of 1,25-dihydroxyvitamin D₃ and its analogs. In this review we will give an overview of the action of vitamin D analogs in tumor cells and look forward how these compounds could be introduced in the clinical practice.

TGF-β prevents phosphate-induced osteogenesis through inhibition of BMP and Wnt/β-catenin pathways

BACKGROUND

Transforming growth factor-β (TGF-β) is a key cytokine during differentiation of mesenchymal stem cells (MSC) into vascular smooth muscle cells (VSMC). High phosphate induces a phenotypic transformation of vascular smooth muscle cells (VSMC) into osteogenic-like cells. This study was aimed to evaluate signaling pathways involved during VSMC differentiation of MSC in presence or not of high phosphate.

RESULTS

Our results showed that TGF-β induced nuclear translocation of Smad3 as well as the expression of vascular smooth muscle markers, such as smooth muscle alpha actin, SM22α, myocardin, and smooth muscle-myosin heavy chain. The addition of high phosphate to MSC promoted nuclear translocation of Smad1/5/8 and the activation of canonical Wnt/β-catenin in addition to an increase in BMP-2 expression, calcium deposition and alkaline phosphatase activity. The administration of TGF-β to MSC treated with high phosphate abolished all these effects by inhibiting canonical Wnt, BMP and TGF-β pathways. A similar outcome was observed in high phosphate-treated cells after the inhibition of canonical Wnt signaling with Dkk-1. Conversely, addition of both Wnt/β-catenin activators CHIR98014 and lithium chloride enhanced the effect of high phosphate on BMP-2, calcium deposition and alkaline phosphatase activity.

CONCLUSIONS

Full VSMC differentiation induced by TGF-β may not be achieved when extracellular phosphate levels are high. Moreover, TGF-β prevents high phosphate-induced osteogenesis by decreasing the nuclear translocation of Smad 1/5/8 and avoiding the activation of Wnt/β-catenin pathway.

Interaction of vitamin D with membrane-based signaling pathways

Many studies in different biological systems have revealed that 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂D₃) modulates signaling pathways triggered at the plasma membrane by agents such as Wnt, transforming growth factor (TGF)-β, epidermal growth factor (EGF), and others. In addition, 1α,25(OH)₂D₃ may affect gene expression by paracrine mechanisms that involve the regulation of cytokine or growth factor secretion by neighboring cells. Moreover, post-transcriptional and post-translational effects of 1α,25(OH)₂D₃ add to or overlap with its classical modulation of gene transcription rate. Together, these findings show that vitamin D receptor (VDR) cannot be considered only as a nuclear-acting, ligand-modulated transcription factor that binds to and controls the transcription of target genes. Instead, available data support the view that much of the complex biological activity of 1α,25(OH)₂D₃ resides in its capacity to interact with membrane-based signaling pathways and to modulate the expression and secretion of paracrine factors. Therefore, we propose that future research in the vitamin D field should focus on the interplay between 1α,25(OH)₂D₃ and agents that act at the plasma membrane, and on the analysis of intercellular communication. Global analyses such as RNA-Seq, transcriptomic arrays, and genome-wide ChIP are expected to dissect the interactions at the gene and molecular levels.

Gene expression profiles in human and mouse primary cells provide new insights into the differential actions of vitamin D3 metabolites

1α,25-Dihydroxyvitamin D₃ (1α,25(OH)₂D₃) had earlier been regarded as the only active hormone. The newly identified actions of 25-hydroxyvitamin D₃ (25(OH)D₃) and 24R,25-dihydroxyvitamin D₃ (24R,25(OH)₂D₃) broadened the vitamin D₃ endocrine system, however, the current data are fragmented and a systematic understanding is lacking. Here we performed the first systematic study of global gene expression to clarify their similarities and differences. Three metabolites at physiologically comparable levels were utilized to treat human and mouse fibroblasts prior to DNA microarray analyses. Human primary prostate stromal P29SN cells (hP29SN), which convert 25(OH)D₃ into 1α,25(OH)₂D₃ by 1α-hydroxylase (encoded by the gene CYP27B1), displayed regulation of 164, 171, and 175 genes by treatment with 1α,25(OH)₂D₃, 25(OH)D₃, and 24R,25(OH)₂D₃, respectively. Mouse primary Cyp27b1 knockout fibroblasts (mCyp27b1^−/−), which lack 1α-hydroxylation, displayed regulation of 619, 469, and 66 genes using the same respective treatments. The number of shared genes regulated by two metabolites is much lower in hP29SN than in mCyp27b1^−/−. By using DAVID Functional Annotation Bioinformatics Microarray Analysis tools and Ingenuity Pathways Analysis, we identified the agonistic regulation of calcium homeostasis and bone remodeling between 1α,25(OH)₂D₃ and 25(OH)D₃ and unique non-classical actions of each metabolite in physiological and pathological processes, including cell cycle, keratinocyte differentiation, amyotrophic lateral sclerosis signaling, gene transcription, immunomodulation, epigenetics, cell differentiation, and membrane protein expression. In conclusion, there are three distinct vitamin D₃ hormones with clearly different biological activities. This study presents a new conceptual insight into the vitamin D₃ endocrine system, which may guide the strategic use of vitamin D₃ in disease prevention and treatment.

Acceleration of bone repair in NOD/SCID mice by human monoosteophils, novel LL-37-activated monocytes

Background

An incomplete understanding of bone forming cells during wound healing and ectopic calcification has led to a search for circulating cells that may fulfill this function. Previously, we showed that monoosteophils, a novel lineage of calcifying/bone-forming cells generated by treatment of monocytes with the natural peptide LL-37, are candidates. In this study, we have analyzed their gene expression profile and bone repair function.

Methods and Findings

Human monoosteophils can be distinguished from monocytes, macrophages and osteoclasts by their unique up-regulation of integrin α3 and down-regulation of CD14 and CD16. Monoosteophils express high mRNA and protein levels of SPP1 (osteopontin), GPNMB (osteoactivin), CHI3L1 (cartilage glycoprotein-39), CHIT1 (Chitinase 1), MMP-7, CCL22 and MAPK13 (p38MAPKδ). Monocytes from wild type, but not MAPK13 KO mice are also capable of monoosteophil differentiation, suggesting that MAPK13 regulates this process. When human monoosteophils were implanted in a freshly drilled hole in mid-diaphyseal femurs of NOD/SCID mice, significant bone repair required only 14 days compared to at least 24 days in control treated injuries.

Conclusion

Human derived monoosteophils, characterized as CD45⁺α3⁺α3β⁺CD34⁻CD14⁻BAP (bone alkaline phosphatase)⁻ cells, can function in an animal model of bone injury.

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.