Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The decrease in estrogen levels that follows the onset of menopause results in rapid bone loss and osteoporosis. The major effect of estrogen deficiency on bone metabolism is an increase in the rate of bone resorption, but the precise mechanism by which this occurs remains unresolved. A recently developed technique for the isolation of avian osteoclasts has been modified to obtain highly purified multinucleated cells from human giant cell tumors. These osteoclast-like cells have been examined for evidence of estrogen receptors (ERs) and responses to 17 beta-estradiol (17 beta-E2). Analysis of giant-cell RNA demonstrated expression of ER mRNA. Furthermore, immunoblot analysis revealed that the giant cells contained a 66-kDa protein that was recognized by a monoclonal antibody specific for the human ER. When isolated multinucleated cells were cultured on slices of bone, there was a dose-dependent decrease in resorption in response to treatment detectable at 10 pM 17 beta-E2. Treatment with 10 nM 17 alpha-estradiol or vehicle (control) did not inhibit resorption. Moreover, the multinucleated cells isolated from these tumors had decreased mRNA levels for cathepsin B, cathepsin D, and tartrate-resistant acid phosphatase (TRAP) as well as secreted cathepsin B and TRAP enzyme activity in response to treatment with 10 nM 17 beta-E2. In contrast to these data, no change in gene expression was detected in mononuclear cells from these tumors in response to 17 beta-E2 treatment. These data support the proposition that human osteoclasts are target cells for estrogen and that estrogen can inhibit bone resorption by human osteoclasts.
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PMID:Human giant cell tumors of the bone (osteoclastomas) are estrogen target cells. 820 73

The human diet contains industrial-derived, endocrine-active chemicals and higher levels of naturally occurring compounds that modulate multiple endocrine pathways. Hazard and risk assessment of these mixtures is complicated by noadditive interactions between different endocrine-mediated responses. This study focused on estrogenic chemicals in the diet and compared the relative potencies or estrogen equivalents (EQs) of the daily consumption of xenoestrogenic organochlorine pesticides in food (2.44 micrograms/day) with the EQs in a single 200-ml glass of red cabernet wine. The reconstituted organochlorine mixture contained 1,1,1-trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl)ethane, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene, endosulfan-1, endosulfan-2, p,p'-methoxychlor, and toxaphene; the relative proportion of each chemical in the mixture resembled the composition reported in a recent U.S. Food and Drug Administration market basket survey. The following battery of in vitro 17 beta-estradiol (E2)-responsive bioassays were utilized in this study: competitive binding to mouse uterine estrogen receptor (ER); proliferation in T47D human breast cancer cells; luciferase (Luc) induction in human HepG2 cells transiently cotransfected with C3-Luc and the human ER, rat ER-alpha, or rat ER-beta; induction of chloramphenicol acetyltransferase (CAT) activity in MCF-7 human breast cancer cells transfected with E2-responsive cathepsin D-CAT or creatine kinase B-CAT plasmids. For these seven in vitro assays, the calculated EQs in extracts from 200 ml of red cabernet wine varied from 0.15 to 3.68 micrograms/day. In contrast, EQs for consumption of organochlorine pesticides (2.44 micrograms/day) varied from nondetectable to 1.24 ng/day. Based on results of the in vitro bioassays, organochlorine pesticides in food contribute minimally to dietary EQ intake.
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PMID:Comparative estrogenic activity of wine extracts and organochlorine pesticide residues in food. 986 Aug 91

The BRCA1 gene was previously found to inhibit the transcriptional activity of the estrogen receptor [ER-alpha] in human breast and prostate cancer cell lines. In this study, we found that breast cancer-associated mutations of BRCA1 abolish or reduce its ability to inhibit ER-alpha activity and that domains within the amino- and carboxyl-termini of the BRCA1 protein are required for the inhibition. BRCA1 inhibition of ER-alpha activity was demonstrated under conditions in which a BRCA1 transgene was transiently or stably over-expressed in cell lines with endogenous wild-type BRCA1 and in a breast cancer cell line that lacks endogenous functional BRCA1 (HCC1937). In addition, BRCA1 blocked the expression of two endogenous estrogen-regulated gene products in human breast cancer cells: pS2 and cathepsin D. The BRCA1 protein was found to associate with ER-alpha in vivo and to bind to ER-alpha in vitro, by an estrogen-independent interaction that mapped to the amino-terminal region of BRCA1 (ca. amino acid 1-300) and the conserved carboxyl-terminal activation function [AF-2] domain of ER-alpha. Furthermore, several truncated BRCA1 proteins containing the amino-terminal ER-alpha binding region blocked the ability of the full-length BRCA1 protein to inhibit ER-alpha activity. Our findings suggest that the amino-terminus of BRCA1 interacts with ER-alpha, while the carboxyl-terminus of BRCA1 may function as a transcriptional repression domain. Oncogene (2001) 20, 77 - 87.
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PMID:Role of direct interaction in BRCA1 inhibition of estrogen receptor activity. 1124 6

Several breast cancer tumor models respond to estradiol (E(2)) by undergoing apoptosis, a phenomenon known to occur in clinical breast cancer. Before the application of tamoxifen as an endocrine therapy, high-dose E(2) or diethystilbesterol treatment was successfully used, albeit with unfavorable side effects. It is now recognized that such an approach may be a potential endocrine therapy option. We have explored the mechanism of E(2)-induced tumor regression in our T47D:A18/PKCalpha tumor model that exhibits autonomous growth, tamoxifen resistance, and E(2)-induced tumor regression. Fulvestrant, a selective estrogen receptor (ER) down-regulator, prevents T47D:A18/PKCalpha E(2)-induced tumor growth inhibition and regression when given before or after tumor establishment, respectively. Interestingly, E(2)-induced growth inhibition is only observed in vivo or when cells are grown in Matrigel but not in two-dimensional tissue culture, suggesting the requirement of the extracellular matrix. Tumor regression is accompanied by increased expression of the proapoptotic FasL/FasL ligand proteins and down-regulation of the prosurvival Akt pathway. Inhibition of colony formation in Matrigel by E(2) is accompanied by increased expression of FasL and short hairpin RNA knockdown partially reverses colony formation inhibition. Classic estrogen-responsive element-regulated transcription of pS2, PR, transforming growth factor-alpha, C3, and cathepsin D is independent of the inhibitory effects of E(2). A membrane-impermeable E(2)-BSA conjugate is capable of mediating growth inhibition, suggesting the involvement of a plasma membrane ER. We conclude that E(2)-induced T47D:A18/PKCalpha tumor regression requires participation of ER-alpha, the extracellular matrix, FasL/FasL ligand, and Akt pathways, allowing the opportunity to explore new predictive markers and therapeutic targets.
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PMID:Estradiol-induced regression in T47D:A18/PKCalpha tumors requires the estrogen receptor and interaction with the extracellular matrix. 1937 79