Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1alpha-25-Dihydroxyvitamin D3 (calcitriol), the biologically active metabolite of vitamin D, is known to regulate calcium and phosphate levels in bone metabolism. It is also known to influence proliferation and differentiation in carcinoma cells mediated by the vitamin D receptor (VDR). The antiproliferative effects of calcitriol are believed to be mediated by the nuclear pathway via binding the activated receptor to vitamin D-responsive elements. This induces the vitamin D-responsive genes. Another possible pathway might be the MAPK-cascade or rapid response pathway. The interaction of calcitriol and the MAP-kinase-cascade was evaluated on VDR-positive MCF-7 cells and VDR-negative MDA-MB-231 breast cancer cells. The cells were incubated with calcitriol solution at 10(-7) M and 10(-9) M, or ethanol as controls, for up to 48 h. The effects of calcitriol were measured by semi-quantitative Western blotting. Calcitriol stimulated the MAP-kinases ERK1 and ERK2. A biphasic activation was found for calcitriol in VDR-positive cells after incubation for 5 to 20 min and from 2 to 24 h. However, early activation of ERK1 and ERK2 was also demonstrated in VDR-negative cells. In the controls, ethanol also induced the MAPK-cascade at 5 to 10 min. Calcitriol induction was demonstrated after incubation from 2 to 24 h. In conclusion, it seems that the early induction of the MAPK-cascade was independent of the VDR. A calcitriol-induced MAPK activation was shown after 4 h, which may have been caused by activation of the nuclear receptor pathway.
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PMID:Modulation of MAPK ERK1 and ERK2 in VDR-positive and -negative breast cancer cell lines. 1688 87

Vitamin D and calcium are metabolically interrelated and highly correlated dietary factors. Experimental studies have shown their anticarcinogenic effects due to their participation in regulating cell proliferation, differentiation, and apoptosis in normal and malignant breast cells. Given the emerging interest in their potential roles in the etiology of breast cancer, we review the current epidemiologic literature on dietary and/or supplemental intakes of vitamin D, endogenous circulating levels of vitamin D, and dietary and/or supplemental intakes of calcium in relation to breast cancer risk. To place these studies in context, we also provide a brief review of other supporting epidemiologic evidence. Despite inconsistent results from the epidemiologic studies, several lines of evidence suggest that vitamin D and calcium may be involved in the development of breast cancer. Specifically, (a) there is some epidemiologic evidence for inverse associations between vitamin D and calcium intakes and breast cancer; (b) serum, plasma, and/or blood levels of vitamin D metabolites have been inversely associated with breast cancer risk in some studies; (c) high sunlight exposure, presumably reflecting vitamin D synthesis in the skin, has been associated with a reduced risk of breast cancer; (d) vitamin D and calcium intakes have been inversely related to breast density, an intermediate end point for breast cancer; (e) calcium has been associated with a reduced risk of benign proliferative epithelial disorders of the breast, putative precursors of breast cancer; and (f) certain polymorphisms of the vitamin D receptor might modify breast cancer susceptibility. To further confirm the potential protective effects of calcium and vitamin D on breast cancer, well-designed cohort studies and clinical trials are warranted.
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PMID:Vitamin D, calcium, and breast cancer risk: a review. 1689 28

Prolactin (PRL) is a hormone that contributes to both the growth and differentiation of mammary epithelial cells, activities likely to impact breast cancer in opposite ways. Whether PRL causes growth or differentiation has been solely attributed to the coexisting steroidal environment, with PRL stimulating mammary gland growth during pregnancy, and then milk production after the postpartum drop in estrogen and progesterone. However, previous work from our laboratory has shown that the form of PRL may also be an important factor. During pregnancy, unmodified PRL (U-PRL) promotes mammary growth, while an increase in phosphorylated PRL, or administration of a molecular mimic of phosphorylated PRL (S179D PRL), inhibits growth. Unknown, however, is whether these forms of PRL have opposite effects on growth in the absence of steroids and whether effects are directly on mammary epithelial cells. To mimic the glandular epithelium in vitro, we used contact-inhibited, differentiated cells and showed that even with these minimally growing cells that treatment with U-PRL caused increased expression of cyclin D1 and cyclin-dependent kinase 4, increased activity of both cdk4 and cdk2, while having no effect on the inhibitory protein, p21. S179D PRL, by contrast, had no effect on cyclin D1 and cdk4 expression, but increased p21 expression and expression of the vitamin D receptor (VDR). We conclude that increased U-PRL or decreased phosphorylated PRL can directly affect cell cycle control proteins in relatively differentiated mammary epithelial cells, thereby implicating the balance between these two forms of PRL in the early promotion of breast cancer.
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PMID:Different forms of prolactin have opposing effects on the expression of cell cycle regulatory proteins in differentiated mammary epithelial cells. 1689 68

The major circulating form of vitamin D is 25-hydroxycholecalciferol [25(OH)D3], which is delivered to target tissues in complex with the serum vitamin D binding protein (DBP). We recently observed that mammary cells can metabolize 25(OH)D3 to 1,25-dihydroxycholecalciferol [1,25(OH)(2)D3], the vitamin D receptor (VDR) ligand, and the objective of our study was to elucidate the mechanisms by which the 25(OH)D3-DBP complex is internalized by mammary cells prior to metabolism. Using fluorescent microscopy and temperature-shift techniques, we found that T-47D breast cancer cells rapidly internalize DBP via endocytosis, which is blunted by receptor-associated protein, a specific inhibitor of megalin-mediated endocytosis. Endocytosis of DBP was associated with activation of VDR by 25(OH)D3 but not 1,25(OH)(2)D3 (as measured by induction of the VDR target gene, CYP24). We also found that megalin and its endocytic partner, cubilin, are coexpressed in normal murine mammary tissue, in nontransformed human mammary epithelial cell lines, and in some established human breast cancer cell lines. To our knowledge, our studies are the first to demonstrate that mammary-derived cells express megalin and cubilin, which contribute to the endocytic uptake of 25(OH)D3-DBP and activation of the VDR pathway.
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PMID:Megalin-mediated endocytosis of vitamin D binding protein correlates with 25-hydroxycholecalciferol actions in human mammary cells. 1705 96

1alpha-hydroxyvitamin D(5) [1alpha(OH)D(5)] is an active vitamin D analog showing promising chemopreventive effect in breast carcinogenesis. We previously reported that estrogen receptor (ER)-positive breast cancer cells were sensitive, whereas ER-negative breast cancer cells were relatively resistant to their antiproliferative effects. In the present study, we used ER-negative MDA-MB231, ER-transfected MDA-MB231 (S30) and ER-positive BT474 cell lines to evaluate the possible association between ER status and cellular sensitivity to 1alpha(OH)D(5) treatment. Our results demonstrate that ER expression in ER-negative breast cancer cells (S30) did not increase the sensitivity to 1alpha(OH)D(5), whereas in ER-positive BT474 cells, the significant antiproliferative effect of 1alpha(OH)D(5) was correlated with the downregulation of ER and progesterone receptor expression. Further analysis indicated that both MDA-MB231 and S30 cells express low vitamin D receptor (VDR) at transcriptional level and protein level. However, transfection of VDR failed to restore the sensitivity to 1alpha(OH)D(5) in MDA-MB231 and S30 cells, although VDR direct target gene CYP24 was more responsive to 1alpha(OH)D(5) treatment in MDA-MB231 and S30 cells overexpressing VDR. In addition, nuclear receptor cofactors NCoR1 and SRC1 that could potentially affect VDR action were also low in both MDA-MB231 and S30 cells in comparison with ER-positive, vitamin D-sensitive BT474 cells. These results suggest that in addition to the increased ER and VDR expression, the intact VDR signaling machinery as present in ER-positive, vitamin D-sensitive cells is essential for the antiproliferative action of vitamin D, whereas the direct VDR target genes such as CYP24 can remain responsive to augmented VDR expression.
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PMID:Overexpression of ER and VDR is not sufficient to make ER-negative MDA-MB231 breast cancer cells responsive to 1alpha-hydroxyvitamin D5. 1713 May 24

1alpha,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)), the most active vitamin D metabolite, regulates proliferation, survival, and differentiation in many cell types. 1,25(OH)(2)D(3) and several less calcemic analogs are in clinical trials against various neoplasias. We studied the effects of 1,25(OH)(2)D(3) on a panel of human breast cancer cells, which show similar vitamin D receptor (VDR) content but variable transcriptional and anti-proliferative responsiveness. In MDA-MB-453 cells, one of the responsive lines, 1,25(OH)(2)D(3) increased cell and nuclear size and induced a change from a rounded to a flattened morphology. By phase contrast, laser confocal and electron microscopy, we found that 1,25(OH)(2)D(3) changed the cytoarchitecture of actin filaments and microtubules and nuclear shape, induced filopodia and lamellipodia, and promoted cell-to-cell contacts via large cytoplasmic extensions. However, although claudin-7 and occludin content in the cells increased upon exposure to 1,25(OH)(2)D(3), these proteins were not located at the plasma membrane probably due to the absence of E-cadherin expression. Additionally, 1,25(OH)(2)D(3) induced the accumulation of alpha(v)-integrin, beta(5)-integrin, focal adhesion kinase (FAK), and paxillin in focal adhesion plaques, concomitant with the increased phosphorylation of the FAK. 1,25(OH)(2)D(3) enhanced MDA-MB-453 and MDA-MB-468 cell adhesion to plastic but decreased adhesion to laminin. The expression of the mesenchymal marker N-cadherin and of the myoepithelial marker P-cadherin was down-regulated by 1,25(OH)(2)D(3) in several breast cancer cell lines. Other myoepithelial proteins such as alpha(6)-integrin, beta(4)-integrin, and smooth muscle alpha-actin (SMA) were also repressed by 1,25(OH)(2)D(3) in MDA-MB-453 and MDA-MB-468 cells. Accordingly, mice lacking VDR (Vdr(-/-)) showed abnormally high levels of SMA and P-cadherin in their mammary gland. These findings show that 1,25(OH)(2)D(3) profoundly affects the phenotype of breast cancer cells, and suggest that it reverts the myoepithelial features associated with more aggressive forms and poor prognosis in human breast cancer.
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PMID:Vitamin D regulates the phenotype of human breast cancer cells. 1728 43

The human 25-hydroxyvitamin D3 (25(OH)D3) 1alpha-hydroxylase, which is encoded by the CYP27B1 gene, catalyzes the metabolic activation of the 25(OH)D3 into 1alpha,25-dihydroxyvitamin D3 (1alpha,25(OH)2D3), the most biologically potent vitamin D3 metabolite. The most important regulator of CYP27B1 gene activity is 1alpha,25(OH)2D3 itself, which down-regulates the gene. The down-regulation of the CYP27B1 gene has been proposed to involve a negative vitamin D response element (nVDRE) that is located approximately 500 bp upstream from transcription start site (TSS). In this study, we reveal the existence of two new VDR-binding regions in the distal promoter, 2.6 and 3.2 kb upstream from the TSS, that bind vitamin D receptor-retinoid X receptor complexes. Since the down regulation of the CYP27B1 gene is tissue- and cell-type selective, a comparative study was done for the new 1alpha,25(OH)2D3-responsive regions in HEK-293 human embryonic kidney and MCF-7 human breast cancer cells that reflect tissues that, respectively, are permissive and non-permissive to the phenomenon of 1alpha,25(OH)2D3-mediated down-regulation of this gene. We found significant differences in the composition of protein complexes associated with these CYP27B1 promoter regions in the different cell lines, some of which reflect the capability of transcriptional repression of the CYP27B1 gene in these different cells. In addition, chromatin architecture differed with respect to chromatin looping in the two cell lines, as the new distal regions were differentially connected with the proximal promoter. This data explains, in part, why the human CYP27B1 gene is repressed in HEK-293 but not in MCF-7 cells.
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PMID:Selective use of multiple vitamin D response elements underlies the 1 alpha,25-dihydroxyvitamin D3-mediated negative regulation of the human CYP27B1 gene. 1742 22

Epidemiologic data have demonstrated that breast cancer incidence is inversely correlated with indices of vitamin D status, including ultraviolet exposure, which enhances epidermal vitamin D synthesis. The vitamin D receptor (VDR) is expressed in mammary epithelial cells, suggesting that vitamin D may directly influence sensitivity of the gland to transformation. Consistent with this concept, in vitro studies have demonstrated that the VDR ligand, 1,25-dihydroxyvitamin D (1, 25D), exerts negative growth regulatory effects on mammary epithelial cells that contribute to maintenance of the differentiated phenotype. Furthermore, deletion of the VDR gene in mice alters the balance between proliferation and apoptosis in the mammary gland, which ultimately enhances its susceptibility to carcinogenesis. In addition, dietary supplementation with vitamin D, or chronic treatment with synthetic VDR agonists, reduces the incidence of carcinogen-induced mammary tumors in rodents. Collectively, these observations have reinforced the need to further define the human requirement for vitamin D and the molecular actions of the VDR in relation to prevention of breast cancer.
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PMID:Vitamin D and prevention of breast cancer. 1772 71

We investigated the association between polymorphism in the androgen receptor (AR) and vitamin D receptor (VDR) genes and breast cancer risk in a large population-based case-control study of genetically homogenous Swedish women. We successfully determined both AR CAG(n) and VDR A(n) genotype in 1,502 women with invasive breast cancer and in 1,510 control women. We did not find any associations between AR or VDR microsatellite lengths and breast cancer when we used a priori determined cutoffs (</=21 or >/=22 repeats for AR and </=18 or >/=19 for VDR) to define long and short alleles. There was statistically significant interaction between VDR genotype and parity, such that women with two short alleles had a halved risk for breast cancer, irrespective of parity, compared with nulliparous women with two long alleles. Homozygosity for the long VDR allele was associated with a more advanced clinical stage at diagnosis. In exploratory analyses, we determined cutoffs based on visual inspection of distributions of allele lengths among cases and controls and found that women carrying two alleles with <20 AR CAG(n) repeats had an increased risk for breast cancer, odds ratio of 1.67 (95% confidence interval, 1.17-2.38), compared with those with two alleles with >/=20 repeats. Women carrying two VDR alleles with <21 A(n) were also at an increased risk, odds ratio of 1.26 (95% confidence interval, 1.04-1.51). Our data do not support major roles for AR or VDR polymorphism as breast cancer risk factors. However, we did find an interaction between VDR genotype and parity that remains to be corroborated.
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PMID:Associations between androgen and Vitamin D receptor microsatellites and postmenopausal breast cancer. 1785 96

Considerable evidence indicates that vitamin D may reduce the risk of several cancers, including breast cancer. This study examined associations of breast cancer with sun exposure, the principal source of vitamin D, and vitamin D receptor gene (VDR) polymorphisms (FokI, TaqI, BglI) in a population-based case-control study of Hispanic, African-American, and non-Hispanic White women aged 35-79 years from the San Francisco Bay Area of California (1995-2003). In-person interviews were obtained for 1,788 newly diagnosed cases and 2,129 controls. Skin pigmentation measurements were taken on the upper underarm (a sun-protected site that measures constitutive pigmentation) and on the forehead (a sun-exposed site) using reflectometry. Biospecimens were collected for a subset of the study population (814 cases, 910 controls). A high sun exposure index based on reflectometry was associated with reduced risk of advanced breast cancer among women with light constitutive skin pigmentation (odds ratio = 0.53, 95% confidence interval: 0.31, 0.91). The association did not vary with VDR genotype. No associations were found for women with medium or dark pigmentation. Localized breast cancer was not associated with sun exposure or VDR genotype. This study supports the hypothesis that sunlight exposure reduces risk of advanced breast cancer among women with light skin pigmentation.
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PMID:Sun exposure, vitamin D receptor gene polymorphisms, and breast cancer risk in a multiethnic population. 1793 1


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