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: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This review is focused on genetic factors that may influence the development and/or appearance of breast cancer metastases. Over the last decade there have been significant advances in the understanding of genetic predisposition to breast cancer. The first breast cancer predisposing gene to be identified was TP53, and this was followed over the next 5 years by two more genes, BRCA1 and BRCA2, which from a population perspective are much more important than TP53. Other rarer genes have subsequently been identified, but the role of more common, less penetrant genes in breast cancer susceptibility remains unknown. Recent work has shown that breast cancers occurring in women carrying germ-line BRCA1 mutations tend to have clinicopathological features that are usually associated with a poor prognosis, such as high grade, estrogen receptor negative status and somatic TP53 mutations. On the other hand, they are usually ERBB2 negative. Whether or not such tumors are more or less likely to metastasize, and hence be associated with a poor outcome, is currently uncertain and has been the subject of much debate. Here, we outline some of the clinicopathological features of hereditary breast cancer, discuss the prognostic studies that have been performed, and introduce some possible new research directions.
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PMID:The contribution of inherited factors to the clinicopathological features and behavior of breast cancer. 1201 34

The estrogen receptor alpha (ERalpha) signaling plays an essential role in breast cancer progression and endocrine therapy. Mitogen-activated protein kinase (MAPK/Erk1/2) has been implicated in ligand-independent activation of ER, resulting in the cross-talk between growth factor and ER mediated signaling. In this study, we examined the effect of the cross-talk on estradiol (E(2))-mediated signaling, tumor growth and its effect on anti-estrogen therapy. Our findings demonstrate that expression of constitutively activated mitogen activated kinase kinase (MEK1), an immediate upstream activator of MAPK in estrogen receptor positive MCF-7 breast cancer cells (MEK/MCF-7), showed an increase in ERalpha-driven transcriptional activation. In MEK/MCF-7 cells maximal transactivation levels were achieved in response to treatment with much lower E(2) concentrations (10(-10) M E(2)) when compared to MCF-7 control cells (10(-8) M E(2)). Furthermore, we have seen an increased association between ERalpha and its nuclear coactivators AIB1 or TIF-2, in MEK/MCF-7 cells relative to those seen in MCF-7 control cells. In addition, in vivo studies show that MEK/MCF-7 cell tumors are approximately threefold larger than those of MCF-7 cell, in the presence of E(2). Immunohistochemical staining demonstrates that progesterone receptor (PR) and pS2, two E(2)-regulated gene products, are significantly increased in MEK/MCF-7 cell tumors compared to those of MCF-7 control tumors, suggesting that activation of ERalpha by MAPK enhances the expression of E(2)-regulated genes and accelerates tumor growth. Remarkably, the antiestrogens tamoxifen and ICI 182,780, were shown both in vitro and in vivo studies to efficiently antagonize the stimulatory effects of E(2) on ER regulated transactivation and tumor growth in MEK/MCF-7 as well as MCF-7 cell lines. Taken together, these data suggest that MAPK/ER cross-talk enhances ERalpha-mediated signaling and accelerates E(2)-dependent tumor growth without diminishing sensitivity to the inhibitory effects of anti-estrogens.
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PMID:MAP kinase/estrogen receptor cross-talk enhances estrogen-mediated signaling and tumor growth but does not confer tamoxifen resistance. 1203 82

Preliminary results of a phase II study of gemcitabine plus trastuzumab in previously treated (up to 3 previous regimens) metastatic breast cancer patients are presented. Patients had histologically confirmed metastatic breast cancer, with 2+ or 3+ tumor HER2 expression. Treatment consisted of gemcitabine 1200 mg/m2 over 30 minutes intravenously on days 1 and 8 every 21 days, and trastuzumab 4 mg/kg over 90 minutes, followed by 2 mg/kg infused over 30 minutes weekly. Treatment was continued until disease progression or unacceptable toxicity occurred. Preliminary results are available on the first 38 patients enrolled. Median patient age was 53 years, 53% had estrogen receptor/progesterone receptor-positive disease, and HER2 staining was 2+ in 39% and 3+ in 61% of patients. There was a median of 3 previously administered (including adjuvant) chemotherapy regimens, and a median of 4.5 treatment cycles per patient has been administered so far. Twelve patients (32%) have had an objective partial response, with a median response duration of 8.6 months. Median time to disease progression is 6.7 months to date, with a median overall survival of 10.2 months. No unexpected toxicities or grade 4 nonhematologic toxicities have been observed; 2 patients developed grade 4 neutropenia and 1 patient had febrile neutropenia. Thus, gemcitabine/ trastuzumab resulted in an encouraging 32% response rate, given the heavily pretreated patient population. Tolerability was good overall, with no unexpected side effects observed.
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PMID:Phase II trial of gemcitabine plus trastuzumab in metastatic breast cancer patients previously treated with chemotherapy: preliminary results. 1205 40

Most highly estrogen responsive genes are synergistically activated by multiple copies of estrogen responsive elements (EREs) capable of binding to the estrogen receptor (ER). We examined here the structural features of the receptor necessary to interact with co-regulatory proteins and to produce a synergistic pattern of activation from multiple EREs. Using full length and truncated variants of ERalpha, we show in transfected mammalian cells that although the carboxyl (AF-2) and the amino (AF-1) terminal activation domains are functionally integrated to induce transcription, AF-1 is critical for mediating synergy. Partial characterization of AF-1 sub-domains revealed that both Box-1 and Box-2 regions (amino acids 41-64 and 87-108, respectively) are essential for a synergistic response to estrogen. We show that members of the p160 family of co-factors and TIF-1 interact with the AF-2 domain of ERalpha. We also found that TIF-2, a member of the p160 family, can interact with the Box-1 region of AF-1. Apparently, structural regions required for the ability of ERalpha to induce transcription synergistically from tandem ERE sequences are also critical for the interaction of the receptor with the co-regulatory proteins.
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PMID:Structural regions of ERalpha critical for synergistic transcriptional responses contain co-factor interacting surfaces. 1208 78

Over-expression of the human epidermal growth factor receptor-2 (HER2/neu) has been observed in many cancers, and is associated with a poor prognosis. Recent adjuvant treatment with anti-HER2 monoclonal antibodies in breast cancer has increased the demand for an evaluation of the HER2/neu status in breast cancer. The aim of this study was to investigate the HER2/neu status in breast cancer by a real-time quantitative polymerase chain reaction (PCR) method using LightCycler (Roche Diagnostics, Mannheim, Germany). DNA samples from the fresh tumor tissues of 27 patients with breast cancer were analyzed in parallel using immunohistochemistry (IHC) and the other prognostic parameters including estrogen receptor, progesterone receptor, cytokeratin, and DNA ploidy. Ten (37%) out of 27 cases tested were positive for HER2/neu, while 16 (73%) out of 22 tested positive through an IHC study. The correlation between the DNA aneuploidy and the positive results for HER2/neu were only observed using the real-time PCR method (p < 0.05). There was no significant correlation between the HER2/neu status and the S-phase fractions of the DNA ploidy or other parameters. This study demonstrated that there is marked discordance in the results for the HER2/neu status according to the various methods used. Real-time quantitative PCR for HER2/neu appears to be clinically useful due to its simplicity and ability to produce rapid results.
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PMID:Evaluation of HER2/neu status by real-time quantitative PCR in breast cancer. 1208 41

Soluble and nuclear estrogen receptor (ER) content was measured by ligand binding assay, and estrogen and progesterone receptors by immunohistochemical assays (ER-ICA and PR-ICA) in 214 patients with breast cancer recruited at the "M. Ascoli" Cancer Hospital Centre in Palermo, Sicily, to assess the discriminant and predictive value of these parameters. On follow-up, data from both ER-ICA and PR-ICA showed a statistically significant difference, PR-positive patients having longer disease-free (DSF) and overall (OS) survival than PR-negative ones. Conversely, ER status did not correlate significantly with both DFS (P = 0.6) and OS (P = 0.2). In particular, PR-positive patients had 59 +/- 18 months DFS and 67 +/- 12 months OS, compared to 51 +/- 22 months DFS and 57 +/- 17 months OS of PR-negative cases. The present evidence implies that a PR-negative status identifies breast cancer patients with early relapse, as also suggested by previous studies. It also agrees with the results of ligand binding assay of ER, where ER status is a good discriminant and predictor of response to endocrine treatment, but is unable to anticipate early relapse in breast cancer patients. Evidence that PR status is a statistically significant prognostic indicator deserves further study to ascertain whether or not PR should be regarded as an ER-dependent parameter or be related to other biological variables such as growth factor (e.g., EGF), oncogene (e.g., Her2/Neu), or tumor suppressor gene (e.g., p53) products.
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PMID:Ligand binding and cytochemical analysis of estrogen and progesterone receptors in relation to follow-up in patients with breast cancer. 1209 34

Clinical observations suggest that human breast tumors can adapt in response to endocrine therapy by developing hypersensitivity to estradiol. To understand the mechanisms responsible, we examined estrogenic stimulation of cell proliferation in a model system and provided evidence that long-term deprivation of estradiol causes adaptive hypersensitivity. The enhanced responses to estradiol do not involve mechanisms acting at the level of transcription of estrogen regulated genes. We found no evidence of hypersensitivity when examining the effects of estradiol on regulation of c-myc, pS2, progesterone receptor, several ER reporter genes or c-myb in hypersensitive cells. On the other hand, deprivation of breast cells long term was found to up-regulate a separate pathway whereby the estrogen receptor co-opts a classical growth factor pathway and induces rapid non-genomic effects. Through this pathway, estradiol caused rapid activation of mitogen-activated protein (MAP) kinase. In exploring the mechanisms mediating this event, we found that estradiol binds to cell membrane associated estrogen receptors and causes phosphorylation of Shc, an adaptor protein usually involved in growth factor signaling pathways. ERalpha was found to complex with Shc under these conditions. In turn, Shc bound Grb-2 and Sos which resulted in the activation of MAP kinase. The pure antiestrogen, ICI 182,780, blocked several steps in the rapidly responding ER alpha, Shc, MAP kinase pathway. These non-genomic effects of estradiol produced biologic effects by activating Elk and by inducing morphologic changes in cell membranes. Using confocal microscopy, we demonstrated that estradiol caused a rapid alteration in membrane ruffling, the formation of pseudopodia and translocation of ER alpha to regions contiguous with the cell membrane. These morphologic effects could be blocked with a pure anti-estrogen. We conclude that long-term estradiol deprived cells utilize both genomic (transcriptional) and rapid, non-genomic estradiol induced pathways. We postulate that synergy between these two pathways acting at the level of the cell cycle is responsible for adaptive hypersensitivity.
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PMID:Adaptive mechanisms induced by long-term estrogen deprivation in breast cancer cells. 1216 Sep 99

To explore the hypothesis that aging not only increases breast cancer incidence but also alters breast cancer biology, we correlated patient age and diagnosis with tumor histology, stage and biomarkers independently determined from two different tumor archives: an American collection of approximately 800 paraffin-embedded and immunohistochemically analyzed primary breast cancers, and an European collection of approximately 3000 cryobanked primary breast cancers analyzed by ligand-binding and enzyme immunoassay (EIA). The prognostic biomarkers chosen for comparison represented surrogate measures of tumor: (i). proliferation, growth and genetic instability (mitotic and apoptotic indices, Ki-67/MIB-1-positivity, nuclear grade, p53-positivity), (ii). endocrine-dependence (estrogen receptor (ER), progesterone receptors (PR), pS2, Bcl2), (iii). growth factor receptor-dependence (ErbB2, EGFR/ErbB1), and (iv). angiogenic, invasive and proteolytic potential (uPA, PAI-1, Cathepsin D, VEGF). No biomarker reflecting tumor angiogenic, invasive or proteolytic potential showed a significant correlation with patient age at diagnosis. In contrast, significant inverse correlations (|r|>0.1; P< or =0.05) were observed for all measures of tumor growth and genetic instability as well as growth factor receptor overexpression (ErbB2 or EGFR positivity). Only one marker of endocrine-dependence, ER expression, showed a significant positive correlation with patient age at diagnosis. In summary, these findings support the hypothesis that breast cancer biology is significantly affected by patient age. In particular, breast tumors arising in older patients have slower growth rates, are more likely to be ER-positive, and are less likely to be p53-positive, EGFR-positive or ErbB2-positive.
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PMID:Age-associated biomarker profiles of human breast cancer. 1220 28

We showed previously in neocortical explants, derived from developing wild-type and estrogen receptor (ER)-alpha gene-disrupted (ERKO) mice, that both 17alpha- and 17beta-estradiol elicit the rapid and sustained phosphorylation and activation of the mitogen-activated protein kinase (MAPK) isoforms, the extracellular signal-regulated kinases ERK1 and ERK2. We proposed that the ER mediating activation of the MAPK cascade, a signaling pathway important for cell division, neuronal differentiation, and neuronal survival in the developing brain, is neither ER-alpha nor ER-beta but a novel, plasma membrane-associated, putative ER with unique properties. The data presented here provide further evidence that points strongly to the existence of a high-affinity, saturable, 3H-estradiol binding site (K(d), approximately 1.6 nm) in the plasma membrane. Unlike neocortical ER-alpha, which is intranuclear and developmentally regulated, and neocortical ER-beta, which is intranuclear and expressed throughout life, this functional, plasma membrane-associated ER, which we have designated "ER-X," is enriched in caveolar-like microdomains (CLMs) of postnatal, but not adult, wild-type and ERKO neocortical and uterine plasma membranes. We show further that ER-X is functionally distinct from ER-alpha and ER-beta, and that, like ER-alpha, it is re-expressed in the adult brain, after ischemic stroke injury. We also confirmed in a cell-free system that ER-alpha is an inhibitory regulator of ERK activation, as we showed previously in neocortical cultures. Association with CLM complexes positions ER-X uniquely to interact rapidly with kinases of the MAPK cascade and other signaling pathways, providing a novel mechanism for mediation of the influences of estrogen on neuronal differentiation, survival, and plasticity.
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PMID:ER-X: a novel, plasma membrane-associated, putative estrogen receptor that is regulated during development and after ischemic brain injury. 1235 13

Methylsulfonyl (MeSO(2)) metabolites of polychlorinated biphenyls (PCBs) and 2,2-bis(4-chlorophenyl)-1,1-dichloroethene (4,4'-DDE), itself a metabolite of the insecticide 4,4'-DDT, are emerging as a major class of contaminants in the tissues of wildlife and humans. We investigated the antiestrogenic capacity and potencies of 3'- and 4'-MeSO(2)-2,2',4,5,5'-pentachlorobiphenyl (CB101) and -2,2',4,5'-tetrachlorobiphenyl (CB49), which are among the most environmentally persistent MeSO(2)-PCBs, and 3-MeSO(2)-4,4'-DDE on estrogen receptor (ER)-dependent gene expression in four cell-based bioassay systems. Congener- and concentration-dependent antagonism of 17beta-estradiol (E2)-induced gene expression, rather than induction of ER-dependent gene expression, was observed for the MeSO(2)-PCBs on lucifierase activity in stably transfected human breast adenocarcinoma T47D cells (ER-CALUX) and vitellogenin (vtg) production in primary hepatocytes from male carp fish (Cyprinus carpio) (CARP-HEP/vtg). 4'-MeSO(2)-CB101 and -CB49 had the highest antagonistic potency (i.e., maximum inhibition of about 70%, LOECs of 1.0 microM and 2.5 microM), whereas 3'-MeSO(2)-CB101 and -CB49 were less antagonistic; the precursor CB101 and MeSO(2)-PCB analog MeSO(2)-2,5-dichlorobenzene had no effect. Relative to the 4-MeSO(2)-PCBs, tamoxifen (IC(50), 0.06 microM and 0.7 microM) was about 40 and 7 times more potent in the ER-CALUX and CARP-HEP/vtg assays, respectively. Congener- and concentration-dependent effects on aryl hydrocarbon receptor-mediated induction of EROD activity (carp hepatocytes), luciferase expression (H4IIE rat hepatoma [H4IIE.luc] cell line), or cell viability were not observed. 3-MeSO(2)-4,4'-DDE was neither estrogenic nor antiestrogenic in either of the bioassays. Inhibitory trends for the MeSO(2)-PCBs in a bioassay based on stably transfected human embryonic kidney cell (HEK293-ERalpha-ERE) were similar to the ER-CALUX and CARP-HEP/vtg bioassays, whereas the antagonism was weaker in a related HEK293-ERbeta-ERE bioassay. Our findings suggest that the 4'-MeSO(2)-PCBs are antiestrogenic in vitro via a reversible or surmountable interaction with fish or human ER, and that the interaction with human ERalpha is apparently favored over ERbeta. MeSO(2)-PCB metabolites are persistent and bioaccumulative contaminants, and therefore, could be potentially active as environmental antiestrogens in wildlife and humans.
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PMID:In vitro antiestrogenic effects of aryl methyl sulfone metabolites of polychlorinated biphenyls and 2,2-bis(4-chlorophenyl)-1,1-dichloroethene on 17beta-estradiol-induced gene expression in several bioassay systems. 1237 85


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