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Vitamin D and microRNA Expression

ABSTRACT: Background: Vitamin D has been observed to affect the expression of a number of genes, however its mechanism of action has not been completely elucidated. MicroRNA molecules have recently been shown to be key mediators of gene regulation. We hypothesised therefore that vitamin D might modulate gene expression by influencing the expression of microRNAs. Methodology/Principal findings: A microRNA array was used to investigate the expression of microRNAs in RNA extracted from cells exposed to calcitriol for 0, 8 or 36 hours. A diverse panel of human cell lines were analysed including Hep-G2, HL60, K562, two fibroblast cell lines (AG09309 and AG09319), and four lymphoblastoid cell lines (GM15084, GM12878, GM07348 and GM07019). When compared between 0, 8 and 36 hours of calcitriol treatment, there were several microRNAs that were differentially regulated but the significance of these was lost after correction for multiple hypothesis testing. Conclusions/Significance: No microRNA showed significantly altered expression after exposure to vitamin D. However, some nominally significant miRNA molecules may warrant further investigation for a potential vitamin D-related role in immune function.

ORGANISM(S): Mus musculus Human gammaherpesvirus 8 JC polyomavirus Rattus norvegicus Betapolyomavirus macacae Murid gammaherpesvirus 4 Homo sapiens Human immunodeficiency virus 1 Human betaherpesvirus 5 Betapolyomavirus hominis Human alphaherpesvirus 1 human gammaherpesvirus 4 Murid betaherpesvirus 1

PROVIDER: GSE20122 | GEO | 2010/02/02

SECONDARY ACCESSION(S): PRJNA124333

REPOSITORIES: GEO

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Project description:Vitamin D may have anti-tumorigenic actions by influencing the gene expression profile of target tissues, which possess vitamin D receptors. We used a more physiological in vitro model, represented by short-term culture of breast cancer tissue slices, to study the transcriptional effects of a near physiological concentration of calcitriol. Methods. Breast cancer fragments were sliced and maintained in culture for 24 hours in the presence or absence (control) of calcitriol 0.5nM or 100nM (called physiological or supra-physiological concentrations). Five and 16 samples were included in a test or validation group and gene expression was analyzed by microarray (using SAM paired analysis) or qPCR, respectively. Results. Nine genes were regulated by calcitriol 0.5nM including CYP24A1, DPP4, EFTUD1 (FDR£0.01), which were up-modulated. However, using a less stringent FDR value (0.25) 61 genes were differentially expressed. Among the down-regulated transcripts were members of the MHC class II complex (HLA-DPA1, HLA-DQA1, HLA-DQA2, HLA-DQB1, HLA-DRA, HLA-DRB1, HLA-DRB3) and IgG binding (FCGR2A, FCGR2B, FCGR2C). There was an enrichment of genes presenting transcription factor binding sites for vitamin D, among the up-regulated genes and for interferon regulatory factor IRF1, among the down-regulated genes. Analyzing calcitriol supra-physiological effects, a more impressive transcriptional modulation was identified and 136 and 60 genes (FDR 0.1) were more and less expressed in treated samples. Up-regulated genes were involved in vitamin metabolic process, regulation of leukocyte-mediated immunity and positive regulation of alpha-beta T cell activation. Many of the induced genes were already reported as vitamin D responsive genes, including CD14, which was also up-regulated in another set of 16 samples. Genes modulated by both calcitriol concentrations were CYP24A1, DPP4, CA2 (these three in both sets of samples), EFTUD1, TKTL1, KCNK3. Conclusion. Small increments in calcitriol concentration, within the physiological range, for a relatively short period of time may exert transcriptional effects in breast cancer samples. Further studies employing physiological concentrations of vitamin D for longer periods of time may help to elucidate the hormone effects in breast cancer treatment and prevention.

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Vitamin D and microRNA Expression

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