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

CCAAT/enhancer binding proteindelta (C/EBPdelta) gene transcription is highly induced in G(0) growth arrested mammary epithelial cells and "loss of function" alterations in C/EBPdelta have been reported in human breast cancer. To gain a better understanding of the positive and negative factors that control C/EBPdelta gene expression we investigated the role of transcriptional activators, coactivators, repressors, histone modifications, chromatin remodeling and basal transcriptional machinery components in growing and growth arrested HC11 mouse mammary epithelial cells. Growth arrest treatments result in increased STAT3 activation (pSTAT3) and increased C/EBPdelta expression. Co-immunoprecipitation and chromatin immunoprecipitation (ChIP) assays demonstrated that pSTAT3 and Sp1 interact and bind to the transcriptionally active C/EBPdelta promoter. ChIP assays performed under exponentially growing (C/EBPdelta non-expressing) conditions demonstrated that the C/EBPdelta promoter is preloaded with transcriptional activators (Sp1 and CREB) and transcriptional machinery components (TBP and RNA Pol II). In contrast, under G(0) growth arrest (C/EBPdelta expressing) conditions ChIP analysis detected pSTAT3, Sp1, NCoA/SRC1, CBP/p300, pCREB, TBP, and serine 2 phosphorylated Pol II (pPol II) in association with the C/EBPdelta proximal promoter. C/EBPdelta promoter-associated histone post-translational modification analysis revealed histone H3 and H4 acetylation and methylation patterns consistent with a constitutively "open" chromatin conformation. Chromatin remodeling experiments demonstrated that BRG1, the ATPase component of the SWI/SNF chromatin remodeling complex, is required for C/EBPdelta transcription. Finally, C/EBPdelta expression is repressed in proliferating mammary epithelial cells by c-Myc via a mechanism that involves the binding of c-Myc:Max dimers to C/EBPdelta promoter-bound Miz-1. These results provide a molecular model of C/EBPdelta transcriptional regulation under G(0) growth arrest conditions.
 ...
PMID:The mouse C/EBPdelta gene promoter is regulated by STAT3 and Sp1 transcriptional activators, chromatin remodeling and c-Myc repression. 1747 7

Mutations in BRCA2 predispose individuals to breast cancer, a consequence of the role of BRCA2 in DNA repair. Human BRCA2 interacts with the recombinase RAD51 via eight BRC repeats. Controversy has existed, however, about whether the BRC interactions are primarily with RAD51 monomers or with the RAD51-DNA helical polymer, and whether there is a single interaction or multiple ones. We show here that the single BRC motif in the Caenorhabditis elegans BRCA2 homolog, CeBRC-2, contains two different RAD-51-binding regions. One of these regions binds only weakly to RAD-51-DNA filaments but strongly to RAD-51 alone and corresponds to the part of human BRC4 crystallized with RAD51. Injection of a peptide corresponding to this region into worms inhibits the normal formation of RAD-51 foci in response to ionizing radiation (IR). Conversely, peptides corresponding to the second region bind strongly to RAD-51-DNA filaments but do not bind to RAD-51 alone. Three-dimensional reconstructions from electron micrographs show that this peptide binds to the RAD-51 N-terminal domain, which has been shown to have a regulatory function. Injection of this peptide into worms before IR leads to a dramatic increase and persistence of IR-induced RAD-51 foci. This peptide also inhibits the RAD-51 ATPase activity, required for filament depolymerization. These results support a model where an interaction with RAD-51 alone is likely involved in filament nucleation, whereas a second independent interaction is involved in stabilization of RAD-51 filaments by BRCA2. The multiple interactions between BRCA2-like molecules and RAD51 provide insights into why mutations in BRCA2 lead to cancer.
 ...
PMID:Stabilization of RAD-51-DNA filaments via an interaction domain in Caenorhabditis elegans BRCA2. 1748 48

Therapeutic concentrations of digitalis drugs inhibit the proliferation of breast cancer cells by inducing the interaction of Na+/K+-ATPase with Src/EGFR, activation of ERK1/2, and the resulting upregulation of cell cycle inhibitor p21Cip1. Quantitative comparison of ouabain dose-response curves for growth arrest and pump inhibition shows that ratio of Ki (pump)/Ki (proliferation) = 7.2. Such large gains in sensitivity are characteristic of several signal transducing pathways of other receptors. Making the reasonable assumption that Na+/K+-ATPase is the only receptor for ouabain, the large amplification factor clearly shows that occupation of a small fraction of pumping Na+/K+-ATPase by digitalis drugs, or endogenous digitalis-like factors, is sufficient to cause near complete inhibition of cell growth. The likely causes of large amplification factor in the signaling function of Na+/K+-ATPase include (a) interactions among the protomers of Na+/K+-ATPase in the membrane; and (b) induced clustering of Na+/K+-ATPase oligomers with neighboring proteins. The upstream location of both mechanisms suggests that similar amplifications also occur in other cell types with different digitalis downstream effects; e.g., stimulation of proliferation or hypertrophy.
 ...
PMID:On the importance and mechanism of amplification of digitalis signal through Na+/K+-ATPase. 1753 33

P-glycoprotein (P-gp) pumps multiple types of drugs out of the cell, using energy generated from ATP, and confers multidrug resistance (MDR) on cancer cells. ZD6474 is an orally active, selective inhibitor of the vascular endothelial growth factor receptor, epidermal growth factor receptor, and rearranged during transfection tyrosine kinases. This study was designed to examine whether ZD6474 reverses P-gp-mediated MDR in cancer cells. Here, we show that clinically achievable levels of ZD6474 reverse P-gp-mediated MDR of the P-gp-overexpressing cell lines derived from breast cancer, MCF-7/adriamycin (ADR), and human oral epidermoid carcinoma, KBV200 to ADR, docetaxel, and vinorelbine. This ability to reverse the P-gp-mediated resistance is comparable to that of another frequently used reversal agent known as verapamil. ZD6474 itself moderately inhibits the proliferation of both MCF-7 and MCF-7/ADR cells with almost equal activity, but its inhibitory effect is not altered by co-incubation with verapamil, suggesting that ZD6474 may not be a substrate of P-gp. In addition, ZD6474 increases the intracellular accumulation of the P-gp substrate, rhodamine-123, and ADR, by enhancing the uptake and/or decreasing the efflux of these compounds in resistant cells. Further studies show that ZD6474 stimulates ATPase activity in a dose-dependent manner, which is required for the proper function of P-gp. In contrast, ZD6474 does not inhibit the expression level of P-gp. Our results suggest that ZD6474 is capable of reversing MDR in cancer cells by directly inhibiting the function of P-gp, a finding that may have clinical implications for ZD6474.
 ...
PMID:ZD6474 reverses multidrug resistance by directly inhibiting the function of P-glycoprotein. 1791 40

AAA+ proteins play crucial roles in diverse biological processes via their ATPase-driven remodeling of macromolecular complexes. Here we report our identification of an evolutionarily conserved AAA+ protein, ANCCA/pro2000, endowed with a bromodomain that is strongly induced by estrogen in human breast cancer cells and is a direct target of protooncogene ACTR/AIB1/SRC-3. We found that ANCCA associates directly with estrogen-bound estrogen receptor (ER) alpha and ACTR. It is selectively recruited, upon estrogen stimulation, to a subset of ERalpha target genes including cyclin D1, c-myc, and E2F1 and is required for their estrogen-induced expression as well as breast cancer cell proliferation. Further studies indicate that ANCCA binds and hydrolyzes ATP and is critical for recruitment of coregulator CBP and histone hyperacetylation at the ER target chromatin. Moreover, mutations at the ATP binding motifs rendered ANCCA defective as a coactivator in mediating estrogen induction of gene expression. Together, our findings reveal an unexpected layer of regulatory mechanism in hormone signaling mediated by ANCCA and suggest that hormone-induced assembly of transcriptional coregulator complexes at chromatin is a process facilitated by AAA+ ATPase proteins.
 ...
PMID:ANCCA, an estrogen-regulated AAA+ ATPase coactivator for ERalpha, is required for coregulator occupancy and chromatin modification. 1799 43

Cancer immunotherapy relies on the identification and characterization of tumour antigens that can be recognized by effector T cells. Here, we used a proteomics-based approach to identify tumour antigens recognized by serum antibodies from patients with breast cancer. Specific reactivity against a set of spots was identified and their identity was revealed by MALDI-TOF peptide mass fingerprinting. They include disintegrin and metalloprotease 10, aldolase A, beta-ATPase F1, heat shock protein 27, deaminase, pyruvate dehydrogenase protein X component, and Vimentin. Western blot analysis using recombinant proteins expressed in E. coli confirmed the specific reactivity with patient sera. Several tumour antigens were expressed on the surface of the T7 phage and shown to trigger specific immune responses in BALB/c mice following oral immunisation. Furthermore, these immune responses inhibited tumour growth and metastasis of the 4T1 mammary adenocarcinoma cell line. Collectively, the present data indicate that proteomics-based strategy can identify tumour antigens whose surface display on phages or bacteria can provide an effective strategy for mucosal cancer vaccines. In addition, arrayed phage-displayed tumour antigens could be useful as a serum-based screening test for the detection of several tumour antigens.
 ...
PMID:Mucosal vaccination with phage-displayed tumour antigens identified through proteomics-based strategy inhibits the growth and metastasis of 4T1 breast adenocarcinoma. 1809 64

FANCJ mutations are associated with breast cancer and genetically linked to the bone marrow disease Fanconi anemia (FA). The genomic instability of FA-J mutant cells suggests that FANCJ helicase functions in the replicational stress response. A putative helicase with sequence similarity to FANCJ in Caenorhabditis elegans (DOG-1) and mouse (RTEL) is required for poly(G) tract maintenance, suggesting its involvement in the resolution of alternate DNA structures that impede replication. Under physiological conditions, guanine-rich sequences spontaneously assemble into four-stranded structures (G quadruplexes [G4]) that influence genomic stability. FANCJ unwound G4 DNA substrates in an ATPase-dependent manner. FANCJ G4 unwinding is specific since another superfamily 2 helicase, RECQ1, failed to unwind all G4 substrates tested under conditions in which the helicase unwound duplex DNA. Replication protein A stimulated FANCJ G4 unwinding, whereas the mismatch repair complex MSH2/MSH6 inhibited this activity. FANCJ-depleted cells treated with the G4-interactive compound telomestatin displayed impaired proliferation and elevated levels of apoptosis and DNA damage compared to small interfering RNA control cells, suggesting that G4 DNA is a physiological substrate of FANCJ. Although the FA pathway has been classically described in terms of interstrand cross-link (ICL) repair, the cellular defects associated with FANCJ mutation extend beyond the reduced ability to repair ICLs and involve other types of DNA structural roadblocks to replication.
 ...
PMID:FANCJ helicase defective in Fanconia anemia and breast cancer unwinds G-quadruplex DNA to defend genomic stability. 1842 15

Chalcones are biosynthetic precursors of flavonoids found to possess cytotoxic and chemopreventive activities. In this study, 17 non-basic chalcone analogues were synthesized and evaluated for their ability to modulate the function of either the human wild-type (482R) or mutant (482T) breast cancer resistance protein (BCRP/ABCG2) stably expressed in breast cancer MDA-MB-231 cells. At 5microM, chalcones with 2,4-dimethoxy groups or 2,4-dihydroxyl groups on ring A were found to increase mitoxantrone accumulation to a greater extent than an established BCRP inhibitor, fumitremorgin C. At the same time, these chalcones had negligible effect on calcein accumulation in P-glycoprotein overexpressing MDCKII cells, indicating their potential as selective BCRP inhibitors. Functionally, these compounds were able to increase the sensitivity of BCRP-overexpressing cancer cells to mitoxantrone by 2-5-fold. The effect of chalcone compounds on both wild-type and mutant BCRP ATPase activity was also examined and variable effects were observed. A stimulatory effect was mostly observed with chalcones with 2,4-dimethoxy substitution on ring A which were earmarked as good BCRP inhibitors in the MX accumulation and cytotoxicity assays. These findings underscore the potential of methoxylated and hydroxylated chalcones as selective and potent inhibitors of BCRP whose mode of action may not involve the inhibition of ATPase activity.
 ...
PMID:Modulation of breast cancer resistance protein (BCRP/ABCG2) by non-basic chalcone analogues. 1859 62

The Na+K+-ATPase is a known target of cardiac glycosides such as digitoxin and ouabain. We determined that the enzyme also is a target of the structurally-related triterpene glycoside actein, present in the herb black cohosh. Actein's inhibition of Na+-K+-ATPase activity was less potent than that of digitoxin, but actein potentiated digitoxin's inhibitory effect on Na+-K+-ATPase activity and MDA-MB-453 breast cancer cell growth. We observed different degrees of signal amplification for the two compounds. Actein's inhibitory effect on ATPase activity was amplified 2-fold for cell growth inhibition, whereas digitoxin's signal was amplified 20-fold. Actein induced a biphasic response in proteins downstream of ATPase: low dose and short duration of treatment upregulated NF-kappaB promoter activity, p-ERK, p-Akt and cyclin D1 protein levels, whereas higher doses and longer exposure inhibited these activities. Actein and digitoxin may be a useful synergistic combination for cancer chemoprevention and/or therapy.
 ...
PMID:Actein inhibits the Na+-K+-ATPase and enhances the growth inhibitory effect of digitoxin on human breast cancer cells. 1875 49

The expression of transmembrane transporter multidrug resistance-associated protein 1 (MRP1) confers the multidrug-resistant phenotype (MDR) on cancer cells. Since the activity of the other MDR transporter, P-glycoprotein, is sensitive to membrane perturbation, we aimed to check whether the changes in lipid bilayer properties induced by flavones (apigenin, acacetin) and flavonols (morin, myricetin) were related to their MRP1 inhibitory activity. All the flavonoids inhibited the efflux of MRP1 fluorescent substrate from human erythrocytes and breast cancer cells. Morin was also found to stimulate the ATPase activity of erythrocyte ghosts. All flavonoids intercalated into phosphatidylcholine bilayers as judged by differential scanning calorimetry and fluorescence spectroscopy with the use of two carbocyanine dyes. The model of an intramembrane localization for flavones and flavonols was proposed. No clear relationship was found between the membrane-perturbing activity of flavonoids and their potency to inhibit MRP1. We concluded that mechanisms other than perturbation of the lipid phase of membranes were responsible for inhibition of MRP1 by the flavonoids.
 ...
PMID:Perturbation of the lipid phase of a membrane is not involved in the modulation of MRP1 transport activity by flavonoids. 1902 Aug 11


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>