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)

Abnormalities of the EGF receptor and/or the related ERBB2 receptor occur in a significant proportion of cases of human breast cancer and are important influences in the behaviour of this tumour type. In this report we demonstrate by nucleic acid analysis and immunohistochemistry that the recently recognised third member of this gene family, ERBB3, shows a wide range of expression in breast cancer, and shows stronger immunoreactivity than that observed in normal tissue in 43 out of 195 cases (22%) of primary breast cancer. Overexpression of ERBB3 appears to result from increased levels of gene transcription since in none of the cell lines or primary cancers analysed did we find evidence of gene amplification. High expression of ERBB3 is positively associated with the presence of lymph node metastases, but there was no demonstrable relationship with patient survival in this series.
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PMID:Expression of the ERBB3 gene product in breast cancer. 133 87

Overexpression of the ERBB2 gene in human breast cancer is associated with a poor prognosis and resistance to hormonal treatment and chemotherapy. Oestrogen receptor (ER) positive tumour-derived cell lines are known to express relatively low levels of ERBB2 protein under oestrogenic conditions, but markedly higher levels following withdrawal of oestrogens or administration of tamoxifen. Expression of the closely related ERBB3 gene, which co-operates with ERBB2 in cellular transformation, is now shown to respond to oestrogenic manipulation in a similar way, both responses being mediated largely by transcriptional changes. Six previously undescribed DNase I hypersensitive sites occur within the first intron of ERBB2 in cells that overexpress the gene. A 409 base pair DNA fragment containing one of these sites conferred ER dependent oestrogen inhibition on the ERBB2 promoter in two types of transient transfection assay. DNase I footprinting revealed four separate transcription factor binding sites within this fragment consistent with a role as a transcriptional enhancer. These findings implicate intron 1 sequences in the control of ERBB2 expression for the first time and demonstrate that one site within this region is involved in mediating the transcriptional response to oestrogens. Additionally, there is likely to be synergism between ERBB2 and ERBB3 signalling when both are overexpressed in response to oestrogen inhibition, thereby driving transformed cell behaviour.
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PMID:An intron 1 enhancer element mediates oestrogen-induced suppression of ERBB2 expression. 924 84

HER2 (also known as Neu, ErbB2) is a member of the epidermal growth factor receptor (EGFR; also known as ErbB) family of receptor tyrosine kinases, which in humans includes HER1 (EGFR, ERBB1), HER2, HER3 (ERBB3) and HER4 (ERBB4). ErbB receptors are essential mediators of cell proliferation and differentiation in the developing embryo and in adult tissues, and their inappropriate activation is associated with the development and severity of many cancers. Overexpression of HER2 is found in 20-30% of human breast cancers, and correlates with more aggressive tumours and a poorer prognosis. Anticancer therapies targeting ErbB receptors have shown promise, and a monoclonal antibody against HER2, Herceptin (also known as trastuzumab), is currently in use as a treatment for breast cancer. Here we report crystal structures of the entire extracellular regions of rat HER2 at 2.4 A and human HER2 complexed with the Herceptin antigen-binding fragment (Fab) at 2.5 A. These structures reveal a fixed conformation for HER2 that resembles a ligand-activated state, and show HER2 poised to interact with other ErbB receptors in the absence of direct ligand binding. Herceptin binds to the juxtamembrane region of HER2, identifying this site as a target for anticancer therapies.
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PMID:Structure of the extracellular region of HER2 alone and in complex with the Herceptin Fab. 1261 Jun 29

ERBB2 increases the sensitivity of breast cancer cells to the HSP90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG). This has been attributed to the disruption of ERBB3/ERBB2 heterodimers that maintain a crucial cell survival signal via phosphatidylinositol 3-kinase/AKT. ERBB2 confers a poor clinical outcome in medulloblastoma, the most common malignant pediatric brain tumor. Here, we show that medulloblastoma cell sensitivity to 17-AAG is directly related to ERBB2 expression level. Furthermore, overexpression of exogenous ERBB2 in these cells induces spontaneous homodimerization, further enhancing cell sensitivity to 17-AAG. In contrast to breast cancer cells, this increased sensitivity to 17-AAG does not result from cell dependence on AKT1 activity. Rather, we show that 17-AAG generates a dose- and time-dependent increase in MEK/ERK signaling that is required for the drug to inhibit the proliferation of medulloblastoma cells and that ERBB2 sensitizes medulloblastoma cells to 17-AAG by up-regulating basal MEK/ERK signaling. We further show that down-regulation of MEK1 activity markedly reduces the sensitivity of medulloblastoma, breast, and ovarian cancer cells to 17-AAG, whereas expression of a constitutively active MEK1 potentiates the activity of 17-AAG against these cells. Therefore, intact MEK/ERK signaling may be required for optimal 17AAG activity against a variety of tumor cell types. These data identify a new mechanism by which 17-AAG inhibits the proliferation of cancer cells. Defining the precise mode of action of these agents within specific tumor cell types will be crucial if this class of drugs is to be efficiently developed in the clinic.
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PMID:Medulloblastoma sensitivity to 17-allylamino-17-demethoxygeldanamycin requires MEK/ERKM. 1270 19

The ErbB-driven autocrine growth pathway has been implicated in the development and progression of most common human epithelial malignancies; its blockade is therefore a promising therapeutic strategy, and several candidate drugs are currently undergoing clinical trials. Paradoxically, little is known of the expression pattern of these 4 genes in human tumors, and the clinical significance of the 2 most recently discovered ERBB genes, ERBB3 and ERBB4, is unclear. We used a real-time quantitative RT-PCR assay to quantify ERBB family mRNA copy numbers in a large series of breast tumors from patients with known long-term outcome. ERBB gene expression varied widely, by more than 2 orders of magnitude for ERBB1 and ERBB3, more than 3 orders for ERBB2 and more than 4 orders for ERBB4. We found a positive correlation between ERBB3 and ERBB4 mRNA levels, and a negative correlation between the expression of these 2 latter genes and that of ERBB1. Compared to normal breast tissue, ERBB1 was underexpressed (82.3% of tumors), ERBB2 (16.9%) and ERBB3 (46.2%) were overexpressed and ERBB4 was both underexpressed (24.6%) and overexpressed (29.2%). Links were also found between ERBB status on the one hand and Scarff-Bloom-Richardson (SBR) histopathological grade and estrogen receptor alpha (ERa) status on the other hand. Relapse-free survival (RFS) was shorter among patients with ERBB3-overexpressing tumors (p=0.0092) and longer among those with ERBB4-underexpressing tumors (p=0.0085) relative to patients with normal expression of the respective genes; in contrast, RFS was not significantly influenced by ERBB1 or ERBB2 mRNA status. Only ERBB4 status retained prognostic significance in Cox multivariate regression analysis (p=0.015). Our results point to the involvement of several ErbB-specific ligands (amphiregulin and neuregulin 1) and enzymes or adaptor molecules (PI3K, Src, Shc and Grb7) in the ErbB pathway dysregulation associated with breast cancer. These findings reveal a complex expression pattern of ERBB gene family members in breast tumors and suggest that it is this pattern of expression, rather than the expression of individual family members, that should be taken into account when evaluating antitumoral drugs designed to target these receptors.
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PMID:Prognostic value of ERBB family mRNA expression in breast carcinomas. 1286 37

Given the role of the EGFR/HER2 family of tyrosine kinases in breast cancer, we dissected the molecular basis of EGFR/HER2 kinase signaling in prostate cancer. Using the small molecule dual EGFR/HER2 inhibitor PKI-166, we show that the biologic effects of EGFR/HER-2 pathway inhibition are caused by reduced AR transcriptional activity. Additional genetic and pharmacologic experiments show that this modulation of AR function is mediated by the HER2/ERBB3 pathway, not by EGFR. This HER2/ERBB3 signal stabilizes AR protein levels and optimizes binding of AR to promoter/enhancer regions of androgen-regulated genes. Surprisingly, the downstream signaling pathway responsible for these effects appears to involve kinases other than Akt. These data suggest that the HER2/ERBB3 pathway is a critical target in hormone-refractory prostate cancer.
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PMID:HER2/neu kinase-dependent modulation of androgen receptor function through effects on DNA binding and stability. 1554 23

ERBB4/HER4 (referred to here as ERBB4) is a unique member of the epidermal growth factor receptor (EGFR) family of receptor tyrosine kinases. In contrast to the other three members of the EGFR family (i.e., EGFR, ERBB2/HER2/NEU, and ERBB3), which are associated with aggressive forms of human cancers, ERBB4 expression seems to be selectively lost in tumors with aggressive phenotypes. Consistent with this observation, we show that ERBB4 induces apoptosis when reintroduced into breast cancer cell lines or when endogenous ERBB4 is activated by a ligand. We further show that ligand activation and subsequent proteolytic processing of endogenous ERBB4 results in mitochondrial accumulation of the ERBB4 intracellular domain (4ICD) and cytochrome c efflux, the essential and committed step of mitochondrial regulated apoptosis. Our results indicate that 4ICD is functionally similar to BH3-only proteins, proapoptotic members of the BCL-2 family required for initiation of mitochondrial dysfunction through activation of the proapoptotic multi-BH domain proteins BAX/BAK. Similar to other BH3-only proteins, 4ICD cell-killing activity requires an intact BH3 domain and 4ICD interaction with the antiapoptotic protein BCL-2, suppressed 4ICD-induced apoptosis. Unique among BH3-only proteins, however, is the essential requirement of BAK but not BAX to transmit the 4ICD apoptotic signal. Clinically, cytosolic but not membrane ERBB4/4ICD expression in primary human breast tumors was associated with tumor apoptosis, providing a mechanistic explanation for the loss of ERBB4 expression during tumor progression. Thus, we propose that ligand-induced mitochondrial accumulation of 4ICD represents a unique mechanism of action for transmembrane receptors, directly coupling a cell surface signal to the tumor cell mitochondrial apoptotic pathway.
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PMID:The ERBB4/HER4 intracellular domain 4ICD is a BH3-only protein promoting apoptosis of breast cancer cells. 1677 20

Deregulation of micro-RNAs (miRNAs) is emerging as a major aspect of cancer etiology because their capacity to direct the translation and stability of targeted transcripts can dramatically influence cellular physiology. To explore the potential of exogenously applied miRNAs to suppress oncogenic proteins, the ERBB oncogene family was chosen with a bioinformatics search identifying targeting seed sequences for miR-125a and miR-125b within the 3'-untranslated regions of both ERBB2 and ERBB3. Using the human breast cancer cell line SKBR3 as a model for ERBB2 and ERBB3 dependence, infection of these cells with retroviral constructs expressing either miR-125a or miR-125b resulted in suppression of ERBB2 and ERBB3 at both the transcript and protein level. Luciferase constructs containing the 3' 3'-untranslated regions of ERBB2 and ERBB3 demonstrated approximately 35% less activity in miR-125a- and miR-125b-expressing cells relative to controls. Additionally, phosphorylation of ERK1/2 and AKT was suppressed in SKBR3 cells overexpressing either miR-125a or miR-125b. Consistent with suppression of both ERBB2 and ERBB3 signaling, miR-125a-or miR-125b-overexpressing SKBR3 cells were impaired in their anchorage-dependent growth and exhibited reduced migration and invasion capacities. Parallel studies performed on MCF10A cells demonstrated that miR-125a or miR-125b overexpression produced only marginal influences on the growth and migration of these non-transformed human mammary epithelial cells. These results illustrate the feasibility of using miRNAs as a therapeutic strategy to suppress oncogene expression and function.
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PMID:Coordinate suppression of ERBB2 and ERBB3 by enforced expression of micro-RNA miR-125a or miR-125b. 1711 Mar 80

Protein microarrays allow highly accurate comparison and quantification of numerous biological samples in parallel while requiring only little material. This qualifies protein arrays for systems biology and clinical research where only limited sample material is available, but a precise readout is required. With the introduction of signal normalization steps to monitor the drop size of manually contact-spotted RP protein arrays, the usefulness of normalizer proteins to ensure a high-throughput but inexpensive protein analysis was demonstrated. This approach was applied for the analysis of signaling through ERBB receptor activated kinases in the breast cancer cell line MCF-7. Activation of ERK1/2 and AKT by ERBB1 (EGFR), ERRB2 (HER2/neu), and ERBB3-4 was monitored in a time-resolved manner. Analysis of pathway activation by stimulation with epidermal growth factor and heregulin, or inhibition by blocking with gefitinib or herceptin allowed a characterization of the distinct signaling properties of the different ERBB receptor subtypes.
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PMID:Contact spotting of protein microarrays coupled with spike-in of normalizer protein permits time-resolved analysis of ERBB receptor signaling. 1835 92

ERBB3/HER3 is one of the four members of the epidermal growth factor receptor (ERBB) family. It is activated by binding to ligands Neuregulin-1 and Neuregulin-2. Since ERBB3 lacks intrinsic kinase activity, signal transduction occurs through formation of heterodimers with EGFR, ERBB2, and ERBB4. ERBB3 is a signaling specialist since it has six binding sites for the p85 SH2 adapter subunit of phosphoinositide 3' kinases. These lipid kinases coordinate regulation of metabolism, cell size, proliferation, survival, and angiogenesis. Not surprisingly, ERBB3 signaling has been linked to cancer etiology and progression. In breast cancer, the partnership of ERBB2 and ERBB3 may be crucial for the aggressive properties of cancers with ERBB2 amplification, and may contribute to pre-existing and acquired resistance to therapy. This partnership creates opportunities for improving efficacy of ERBB-targeted pharmaceuticals, by interfering with coupling of ERBB2 to ERBB3 through dimerization inhibitors, and by use of therapeutic compounds that target AKT-dependent pathways activated through ERBB3. Additional therapeutic opportunities may be identified through better understanding of how ERBBs are regulated and deployed in normal mammary gland processes. Work using mouse models has identified the main processes regulated by each of the four ERBBs, which has practical implications in understanding breast cancer etiology, and eventual development of better prognostic, predictive, and therapeutic tools.
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PMID:ERBB3/HER3 and ERBB2/HER2 duet in mammary development and breast cancer. 1845 6


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