Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The incidence of a specific estradiol receptor among the Finnish breast cancer patients was investigated using methods involving dextran-coated charcoal or sucrose density gradient centrifugation techniques. An estradiol receptor was detected in 20 (71%) out of the 28 tumor specimens studied with the following binding site concentrations: 100-1000 fmoles/mg cytosol protein in 12 patients; 10-99 fmoles/mg cytosol protein in 6 patients and below 10 fmoles/mg cytosol protein in 2 patients the lowest detectable level being about 5 fmoles/mg cytosol protein. The apparent intrinsic association constant of the receptor for estradiol-17 beta ranged from 0.4-32 X 10(10) liters/mole in different breast cancer specimens. Estradiol receptor concentration did not seem to correlate well with the age of the patients or the microscopic structure of the tumor. The ligand-binding specificity of the receptor was studied with 25 different estrogen derivatives in 6 separate tumor specimens. The binding proteins in all these tumors showed very similar ligand specificities, despite differences in their histological types and estradiol-binding site concentrations. The phenolic hydroxyl group at C--3 was essential for an effective binding by the receptor, whereas certain modifications in the D-ring structure were well tolerated. As is the case with other steroid receptors, certain hydrophobic substituents seemed to increase the binding of the ligand by the breast cancer estradiol receptor. The in vitro binding affinity and the in vivo biological (estrogenic) potency of some of the steroids investigated did not correlate very well.
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PMID:Steroid binding properties of estradiol receptors in human breast cancer. 17 27

We have demonstrated that natural beta-interferon (beta-IFN) enhances estrogen receptor (ER) mRNA of a human breast cancer cell line, CG-5. Cells were sensitive to the effect of beta-IFN at concentrations ranging from 10 to 100 IU/ml. The increase of ER mRNA was seen after 48 hr of treatment in at least three separate experiments. Our results are in agreement with the previously observed enhancement of receptor protein. In addition, they suggest that the IFN-induced promotion of the antiproliferative activity of drugs which act via ER may be due, in part, to increased receptor synthesis.
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PMID:Effect of natural beta-interferon on estrogen receptor mRNA of breast cancer cells. 129 49

Estrogen receptor (ER) binding has been shown to decrease in breast cancer cell lines exposed to sodium butyrate; however, the underlying mechanisms are unknown. In MCF-7 breast cancer cells, butyrate caused a rapid time- and concentration-dependent decrease in ER mRNA levels, apparent by 3 h at 3 mM butyrate. ER gene transcription rate was decreased and cycloheximide co-treatment did not relieve this inhibitory effect, suggesting that the butyrate effect was not dependent on ongoing protein synthesis. In both MCF-7 and T-47D cells the decrease in ER mRNA was mirrored by an increase in the level of epidermal growth factor receptor (EGF-R) mRNA. A marked inverse relationship exists between ER and EGF-R in human breast cancer biopsies and cell lines, and the reciprocal modulation of these genes by butyrate suggests that the expression of ER and EGF-R may be co-regulated. This relationship was further investigated in lines expressing only one or the other receptor. In the ER-positive EGF-R-negative line, MDA-MB-134-VI, butyrate exposure decreased ER mRNA levels, implying that the regulation of ER mRNA by butyrate is independent of EGF-R expression. However, butyrate decreased EGF-R mRNA in two ER-negative lines, MDA-MB-231 and HBL-100. As this effect differed from that in ER-positive lines, the regulation of EGF-R may depend on the expression of ER. The possibility that ER and EGF-R gene expression are closely linked has implications in the understanding of progression of human breast cancers to a hormone-independent phenotype and for the use of ER and EGF-R levels as independent prognostic indicators.
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PMID:Effect of sodium butyrate on estrogen receptor and epidermal growth factor receptor gene expression in human breast cancer cell lines. 151 34

The cDNAs for variant estrogen receptor (ER) mRNAs previously identified in human breast cancer biopsy samples have been cloned and characterized. Some of these cDNAs are unique to a tumor sample (e.g. clones 24 and 5), while others are present in multiple breast tumor samples (e.g. clone 4). The 5' ends of the variant cDNAs are essentially identical to sequences present in exons 1, 2, and 3 of the normal ER mRNA. However, at points which mark either the exon 2/intron or exon 3/intron boundaries, the variant cDNA sequences diverge and are unrelated to the normal ER mRNA. The unique sequences of clones 24 and 5 are unknown, and the unique sequence of clone 4 is related to the long interspersed repetitive LINE-1 sequences. The variant mRNAs contain open reading frames which could encode proteins containing known functional domains of the normal ER but missing others. In particular, the hormone binding domain of the normal ER is always missing. Furthermore, some of the variant transcripts may encode other unique proteins. In transient expression assays the proteins encoded by the variant ER mRNAs are unable to activate transcription of an estrogen-responsive reporter gene; neither are they able to modulate the ability of normal ER proteins to activate transcription.
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PMID:Characterization of estrogen receptor variant mRNAs from human breast cancers. 160 86

We have examined the ability of estradiol (E2) to regulate the expression of three mRNAs [for pS2, progesterone receptor (PR), and estrogen receptor (ER)], known to be under E2 regulation in the parental E2 growth-responsive MCF-7 cells, in an E2 growth-independent MCF-7 K3), previously isolated from the parental estrogen-dependent MCF-7 K1 human breast cancer cells after long term growth in vitro in the absence of estrogen, acquired estrogen-independent growth in vitro as well as the ability to form tumors in nude mice in vivo without estrogen. We find that the content of pS2 mRNA and the transcription rate of the pS2 gene, while being markedly increased by E2 in MCF-7 K1 cells, are no longer stimulated by E2 in this subline, although protein kinase activators tremendously increase (greater than 10-fold) pS2 mRNA in both K1 and K3 cells. In fact, basal pS2 mRNA levels are elevated 2.8 +/- 0.4-fold in MCF-7 K3 cells, and E2 evokes a concentration-dependent suppression of the pS2 mRNA level. In contrast, PR mRNA in the K3 subline, as in the parental K1 cells, is still up-regulated by E2, and ER mRAN content and the ER mRNA transcription rate are still down-regulated by E2 and show normal E2 dose-response relationships, implying that the ER in this subline is functional. These results demonstrate that the progression to estrogen-independent growth in K3 cells is accompanied by a change in the regulation of some estrogen-induced genes by estrogen. While PR and ER retain normal patterns of regulation by E2, the pS2 gene in the estrogen growth-independent K3 subline is differentially affected and is no longer stimulated by E2. Our data suggest that this altered regulation of the pS2 gene is probably not caused by a defect of the ER or ER regulation in this subline.
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PMID:Differential regulation of gene expression by estrogen in estrogen growth-independent and -dependent MCF-7 human breast cancer cell sublines. 172 71

Cell proliferation and phenotype of cells from female reproductive tissues are regulated by estrogens. It is therefore important to understand how estrogen action can be modulated. It recently has been reported that certain nuclear receptors can antagonize the tumor promoter 12-O-tetradeconylphorbol-13-acetate (TPA) by direct interaction with the transcription factor AP-1, and that the AP-1 constituents cJun and cFos can inhibit receptor activity. This mutual antagonism appears to be based on direct protein-protein interaction. In the human breast cancer cell line MCF-7, TPA leads to growth arrest and altered cell morphology. We have investigated here whether in MCF-7 cells and other cell lines AP-1 and estrogen receptors (ERs) can inhibit each other's activity. We find that TPA or the AP-1 components cJun and cFos can inhibit estradiol-dependent estrogen receptor activity in most cell lines investigated. In addition, ER mRNA is rapidly down-regulated in MCF-7 cells. Gel retardation experiments show that ER DNA binding is inhibited in vitro by cJun protein, while ER also can inhibit cJun DNA binding. However, in vivo we do not observe inhibition of AP-1 activity by ER in the cell lines investigated here. On the contrary, we observed an enhancing effect at low ER concentrations on AP-1. Together our data suggest a new regulatory pathway by which ER activity can be modulated by AP-1. Several mechanisms including ER-AP-1 protein interaction appear to be involved.
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PMID:Inhibition of estrogen receptor activity by the tumor promoter 12-O-tetradeconylphorbol-13-acetate: a molecular analysis. 179 43

A study of HLA phenotype in 151 cases of breast cancer showed an increased occurrence of DR4 antigen (46.8%) as compared to general population (16.3%). Some clinical parameters of DR4-positive and DR4-negative patients were compared. Estradiol receptor-negative tumor was observed in 40% of DR4-positive patients and only in 18.5% of estradiol receptor-negative ones. DR4 positivity was associated with poorer prognosis.
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PMID:[The clinical significance of determining the HLA-DR4 antigen in patients with breast cancer]. 184 31

We studied the effect of interleukin 1 alpha (IL-1 alpha) on estradiol stimulation of cell growth and estrogen receptor (ER) content in MCF-7 human breast cancer cells in vitro to determine if IL-1 alpha altered cellular estradiol responsiveness. We found that IL-1 alpha blocked estradiol-stimulated growth of these cells in a dose-dependent manner (complete antagonism at 1000 units/ml: day 7 mean growth = vehicle, 47.7 micrograms DNA; estradiol 10(-10) M, 95.1; IL-1 alpha/estradiol, 44.6) and at all concentrations of estradiol from 10(-8) to 10(-11) M. IL-1 alpha in combination with trans-hydroxytamoxifen further inhibited estradiol-stimulated growth (vehicle = 44.8 micrograms DNA, estradiol = 108.3, estradiol/trans-hydroxytamoxifen = 47.8, IL-1 alpha/estradiol/trans-hydroxytamoxifen = 3.0, P less than 0.01). Inhibition with trans-hydroxytamoxifen was IL-1 alpha dose dependent (maximum = 97% at 1000 units/ml, P less than 0.01) and estradiol dose dependent (reversible with 10(-8) M estradiol, maximum inhibition at 10(-10) M estradiol). Concomitantly, IL-1 alpha down-regulated ER concentration by 38.0-43.7% (P less than 0.01) as measured by immunoreactivity or Scatchard analysis, respectively. This occurred as early as 3 h without a change in the Kd (vehicle = 0.23 nM, IL-1 alpha = 0.24 nM), persisted for at least 48 h, was dose dependent (maximum, 43.7% at 1000 units/ml, P less than 0.01), and was blocked by cycloheximide. IL-1 alpha, however, did not block estradiol stimulation of progesterone receptor content (vehicle = 221.9, IL-1 alpha = 238.9 fmol/mg protein) and did not block estradiol down-regulation of ER content. Furthermore, IL-1 alpha alone did not alter levels of ER mRNA and did not alter estradiol down-regulation of ER mRNA. These findings indicate that while IL-1 alpha antagonizes estradiol stimulation of growth and reduces ER content, its mechanism may involve other non-estrogen-regulated pathways.
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PMID:Interleukin 1 alpha blocks estradiol-stimulated growth and down-regulates the estrogen receptor in MCF-7 breast cancer cells in vitro. 199 87

Epidermal growth factor receptors (EGF-R) are present in a number of human breast cancer cell lines and tumor biopsies. Furthermore, it has been suggested that EGF-R levels are higher in estrogen receptor negative (ER-) than in ER+ human breast tumors and that EGF-R status may be a prognostic indicator in breast cancer. The present study was undertaken to establish whether there is a quantitative relationship between EGF-R and ER mRNA concentrations in a series of 10 well-characterized human breast cancer cell lines. All cell lines expressed detectable quantities of EGF-R mRNA by Northern analysis but the relative abundance of EGF-R mRNA varied more than 50-fold. Two transcripts corresponding to the 10.5- and 5.8-kb mRNAs described in other cell types were present but in different relative proportions in different cell lines. When these lines were divided into an ER+ and an ER- group based on their ability to bind estradiol, ER- cell lines were shown to express significantly higher concentrations of EGF-R mRNA than did ER+ cell lines (p less than 0.005). Furthermore, linear-regression analysis revealed a significant inverse relationship between ER and EGF-R mRNA concentrations both within the group of 10 human breast cancer cell lines as a whole (r = 0.66) and within the 6 functionally ER + lines (r = 0.77). This demonstration of a significant (p less than 0.005) inverse relationship between the concentrations of ER and EGF-R mRNAs in ER + cell lines raises the possibility of reciprocal regulation of the expression of these genes in human breast cancer.
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PMID:Inverse relationship between estrogen receptor and epidermal growth factor receptor mRNA levels in human breast cancer cell lines. 220 58

Progestin antagonism of estrogen action is thought to be due, at least in part, to progestin down-regulation of the estrogen receptor (ER). The molecular mechanisms subserving this effect, and the functional consequences in terms of target cell sensitivity to estrogens, are poorly understood. The present study was undertaken to address these issues with particular emphasis on progestin regulation of ER gene expression at the mRNA level. The T-47D human breast cancer cell line was treated with the synthetic progestin, ORG 2058, and the resultant changes in ER mRNA and ER levels determined by Northern analysis and radioligand binding, respectively. Treatment of T-47D cells with ORG 2058 resulted in rapid down-regulation of ER mRNA levels to a nadir of 35-40% of control by 6 h. This fall in ER mRNA levels was accompanied by a slower but more sustained fall in ER binding to a nadir of 20% of control at 24 h. Between 12 and 24 h ER mRNA levels recovered partially while ER ligand binding continued to fall. At 48 h both ER mRNA and ER concentrations remained depressed, although the latter to a greater extent. ER mRNA half-life was determined by [3H]uridine incorporation to be approximately 60 min and was unaffected by progestin treatment during the early rapid phase of ER mRNA down-regulation. These data demonstrate that progestins cause rapid down-regulation of the ER mRNA and suggest that during the early rapid phase of this effect, reduced transcription of the ER gene rather than altered ER mRNA half-life mediate this effect.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Progestin regulation of estrogen receptor messenger RNA in human breast cancer cells. 223 41


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