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  • 1
    ISSN: 1573-7276
    Keywords: breast cancer ; cell proliferation ; invasion ; migration ; 1α ; 25-dihydroxyvitamin D3
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Using the Boyden chamber invasion assay, the effect of 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3] on the invasiveness of the highly invasive, oestrogen receptor-negative human breast cancer cell line MDA-MB-231 was examined. The MDA-MB-231 cells were shown to contain high-affinity receptors for 1α,25(OH)2D3 with a Kd of 1.5 × 10−11 M. When the cells were treated with 1α,25(OH)2D3 for 4 days before the assay was performed, a dose-dependent inhibition of their invasive potential was demonstrated. Fifty per cent inhibition of invasion was obtained with a concentration of 13 pM of 1α,25(OH)2D3. However, when the cells were treated for only 6 h during the assay, no inhibitory effect was seen. The process of migration was also affected by treatment with 1α,25(OH)2D3 for 4 days, although the inhibition was not of the same magnitude as seen for the invasion. Fifty per cent inhibition of migration occurred at a concentration of 3.2 nM of 1α,25(OH)2D3 (250 times higher than in the invasion assay). Inhibition of invasion and migration was not due to the known anti-proliferative effect of 1α,25(OH)2D3, as no growth reduction could be demonstrated with treatment up to 5 days. Based on the present investigation it can therefore be concluded that 1α,25(OH)2D3 is able to inhibit tumour cell invasiveness by a mechanism which is not exclusively based on its anti-proliferative and anti-migrative effects.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0730-2312
    Keywords: vitamin D analogues ; vitamin D receptor ; ligand binding ; limited protease digestion ; ligand-dependent gel shift assay ; gene regulation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The nuclear hormone 1α,25-dihydroxyvitamin D3 (VD) has important cell-regulatory functions but also a strong calcemic effect. Therefore, various VD analogues have been synthesized and screened for their biological profile. In order to gain more insight into the molecular basis of the high antiproliferative but low calcemic action of the VD analogue EB1089, we characterized this compound in comparison to five structurally related VD analogues. The activities of the six VD analogues in in vitro assays (limited protease digestion assays for determining interaction with monomeric vitamin D receptor (VDR), ligand-dependent gel shift assays for showing the increase of DNA binding of VDR-retinoid X receptor (RXR) heterodimers, and reporter gene assays on different types of VD response elements for demonstrating the efficacy in nuclear VD signalling) were found to represent their biological potency (antiproliferative effect on different malignant cell lines). In this series, EB1089 proved to be the most potent VD analogue; that is, every structural modification (20-epi configuration, cis-configuration at position C24, or changes at the ethyl groups at position C25) appeared to reduce the determined activities mediated through the VDR of these analogues. Moreover, the modifications of EB1089 resulted in a loss of VD response element selectivity, suggesting that this parameter is very critical for the biological profile of this VD analogue. J. Cell. Biochem. 71:340-350, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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