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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Breast cancers often have deregulated hepatocyte growth factor (HGF) and c-Met signaling that results in increased tumor growth and invasion. Elucidating the mechanism responsible for HGF/c-Met action in breast cancer progression has been difficult as c-Met communicates with a number of secondary receptors that can lead to various pathological outcomes. Understanding how these secondary receptors facilitate HGF/c-Met cellular responses will aid in the development of better therapeutic treatment options for breast cancer patients with elevated HGF signaling. In the present study it was shown that the epidermal growth factor receptor (EGFR) plays a significant role in HGF/c-Met mediated biological activities indicative of advanced tumor pathology, including enhanced proliferation and invasion. The clinically relevant EGFR inhibitor gefitinib was used to determine the role of EGFR in HGF-induced proliferation and motility in several mammary carcinoma cells including PyVmT, MDA-MB-231 and 4T1. Our analyses indicated that EGFR inhibition significantly blocked HGF activation of c-Met and EGFR and that inhibition of these pathways mitigated HGF induced proliferation and motility. The data indicate that this inhibition was not through a direct effect of gefitinib on c-Met, but that EGFR is necessary for c-Met activation in the assays performed. These results provide a novel mechanism of action for EGFR as a mediator of HGF signaling thereby linking EGFR to the oncogenic potential of c-Met in mammary carcinomas cells.
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PMID:Epidermal growth factor receptor plays a significant role in hepatocyte growth factor mediated biological responses in mammary epithelial cells. 1749 20

Inflammatory breast carcinoma (IBC) is a rare but very aggressive tumour phenotype. Increased c-Met protein expression correlates with reduced survival and a higher metastatic risk in many human malignancies, including breast cancer Several studies have shown that c-Met protein is targetable by specific drugs. Here we compared c-Met expression in IBC (n = 41) and non IBC (n = 480). Two microarrays of IBC and non IBC tissues were constructed and standardized. C-Met, P13K and E-cadherin were immunodetected (Ven-tana Benchmark Autostainer) on serial sections. The results were quantified with an automated image analysis device (SAMBA Technologies) by immunoprecipitate densitometry of each core section (0.6 microns thick). We found that (i) c-Met is significantly overexpressed in IBC compared to non IBC (p < 0. 001), (ii) P13K is also overexpressed (p < 0.001) in IBC, suggesting that overexpressed c-Met is functionally active, at least through the PI3K signal transduction pathway ; and (iii) E-cadherin is paradoxically overexpressed in IBC. We conclude that c-Met may constitute a target for specific therapy in patients with poor-prognosis malignancies like IBC Automated image analysis of TMA is a valuable tool for high-throughput quantification of the immunohistochemical expression of the tumor proteome.
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PMID:[High-throughput quantification of tissue microarrays: identification of candidate target proteins in inflammatory breast cancer]. 1796 54

We have shown that administration of alpha-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase (ODC), the first and rate-limiting enzyme in polyamine (PA) biosynthesis, reduces the invasive and metastatic properties of MDA-MB-435 breast cancer cells while activating multiple signal transduction pathways, including MAPK, Stat3, Stat1, and JNK. Since the activity of these signaling mechanisms is frequently regulated by upstream tyrosine kinases (TKs), we tested whether non-receptor and receptor TKs may be involved in the signaling and biological effects of DFMO in MDA-MB-435 cells. Treatment with DFMO (1 mM for 48 h) did not affect Src phosphorylation (Tyr 416). Administration of the Src-family members inhibitor PP-1 (1 microM), blocked Src phosphorylation in the absence and in the presence of DFMO, but did not block the signaling effects of DFMO (increased phosphorylation of Stat3, Stat1, ERK and JNK). PP-1 treatment, on the other hand, inhibited the invasiveness of MDA-MB-435 cells in matrigel and potentiated the anti-invasive effect of DFMO. Next, we focused on the role of receptor TK. Western analysis of cell lysates from MDA-MB-435 cells failed to show the presence of EGF-R and HER-2neu but demonstrated the expression of c-Met, the receptor for hepatocyte growth factor (HGF). Therefore, we tested the effect of DFMO on the HGF/c-Met pathway which is strongly implicated in the progression of human breast cancer. We found that DFMO treatment blocked HGF-induced c-Met phosphorylation in MDA-MB-435 cells, suggesting that its anti-invasion action may be mediated, at least in part, by blocking c-Met signaling. Next, we showed that 1 mM DFMO suppressed HGF induced invasiveness of MDA-MB-435 cells in matrigel. Combination administration of DFMO with suboptimal doses of PHA-665752, a specific c-Met inhibitor, reduced invasiveness to an even greater extent than the individual treatment. These findings indicate that Src-family members, while not involved in DFMO action, promote invasiveness of breast cancer cells and their inhibition may enhance the antitumor effect of PA depletion. Our data also point to inhibition of HGF/c-Met pathway as a possible novel approach to enhancing the antitumor action of DFMO.
Breast Cancer Res Treat 2008 Nov
PMID:Role of non-receptor and receptor tyrosine kinases (TKs) in the antitumor action of alpha-difluoromethylornithine (DFMO) in breast cancer cells. 1809 46

Acquisition of invasive characteristics is a hallmark of breast carcinoma progression. During this phenomenon, Ets-1 transcription factor overexpression is induced and associated with breast cancer invasiveness, and poor prognosis. We hypothesized that Ets-1 transcription factor could be the orchestrator of a genetic program inducing the expression of genes necessary for cell motility, as postulated by the tumor microenvironment invasion model. We aimed at elucidating the role of Ets-1 in the molecular control of mammary cancer cell invasion and aggressiveness within their matrix environment. To that purpose, mouse mammary tumor MMT epithelial cells were engineered to stably overexpress Ets-1, or the dominant negative Ets-1 DNA Binding domain. The biological function of Ets-1 was assessed in three-dimensional extracellular matrix systems recreating a microenvironmental architecture resembling in vivo geometric constraints. Ets-1 overexpression provided MMT cells with a motile and invasive phenotype, leading to cell scattering, and impairing multicellular organization in matrix-mimicking gels. We evidenced that Ets-1 promoted HGF/SF activation, and the expression of its receptor, c-Met. Ets-1 also orchestrated switches in integrin expression pattern, towards a pro-migratory and malignant phenotype. Moreover, Ets-1 concomitantly triggered matrix metalloproteinases (MMP) expression and activation, thus contributing to cell scattering. Functional relevance of these observations was confirmed with blocking antibodies or MMP inhibitors. Our data highlight a critical role for Ets-1 in the orchestration of a network of molecular and phenotypic events, converging to enhance malignant features and invasion by mammary cancer cells of their environment. Ets-1 overexpression hence appears as a probable key step for breast cancer progression.
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PMID:Ets-1 triggers and orchestrates the malignant phenotype of mammary cancer cells within their matrix environment. 1818 Nov 72

That metastatic tumor cells grow in selective non-native environments suggests an ability to differentially respond to local microenvironments. BRMS1, like other metastasis suppressors, halts ectopic growth (metastasis) without blocking orthotopic tumor formation. BRMS1-expressing tumor cells reach secondary sites but do not colonize distant tissues, compelling the hypothesis that BRMS1 selectively restricts the ability of tumor cells to respond to exogenous regulators in different tissues. Here we report that BRMS1 expression in metastatic human breast cancer cells leads to a selective reduction in epidermal growth factor receptor expression and downstream (AKT) signaling. Signaling through another receptor tyrosine kinase, hepatocyte growth factor receptor (c-Met), remains unaltered despite reduced levels of the signaling intermediate phosphatidylinositol (4,5)-bisphosphate. Interestingly, reduced downstream calcium signaling is observed following treatment with platelet-derived growth factor, consistent with decreased phosphatidylinositol (4,5)-bisphosphate. However, platelet-derived growth factor receptor expression is unaltered. Thus, BRMS1 differentially attenuates cellular responses to mitogenic signals, not only dependent upon the specific signal received, but at varying steps within the same signaling cascade. Specific modulation of signaling responses received from the microenvironment may ultimately dictate which environments are permissive/restrictive for tumor cell growth and provide insights into the biology underlying metastasis.
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PMID:Breast cancer metastasis suppressor-1 differentially modulates growth factor signaling. 1866 70

The recepteur d'origine nantais (RON) is a receptor tyrosine kinase (RTK) in the scatter factor family, which includes the c-Met receptor. RON exhibits increased expression in a significant number of human breast cancer tissues as well as in many established breast cancer cell lines. Recent studies have indicated that in addition to ligand-dependent signaling events, RON also promotes signals in the absence of its only known ligand, MSP, when expressed in epithelial cells. In this study, we found that when expressed in MCF-10A breast epithelial cells, RON exhibits both MSP-dependent and MSP-independent signaling, which lead to distinct biological outcomes. In the absence of MSP, RON signaling promotes cell survival, increased cell spreading and enhanced migration in response to other growth factors. However, both RON-mediated proliferation and migration require the addition of MSP in MCF-10A cells. Both MSP-dependent and MSP-independent signaling by RON are mediated in part by Src family kinases. These data suggest that RON has two alternative modes of signaling that can contribute to oncogenic behavior in normal breast epithelial cells.
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PMID:The RON receptor tyrosine kinase promotes MSP-independent cell spreading and survival in breast epithelial cells. 1883 80

We previously described the novel zinc finger protein ZKSCAN3 as a new "driver" of colon cancer progression. To investigate the underlying mechanism and because the predicted structural features (tandem zinc fingers) are often present in transcription factors, we hypothesized that ZKSCAN3 regulates the expression of a gene(s) favoring tumor progression. We employed unbiased screening to identify a DNA binding motif and candidate downstream genes. Cyclic amplification and selection of targets using a random oligonucleotide library and ZKSCAN3 protein identified KRDGGG as the DNA recognition motif. In expression profiling, 204 genes were induced 2-29-fold, and 76 genes reduced 2-5-fold by ZKSCAN3. To enrich for direct targets, we eliminated genes under-represented (<3) for the ZKSCAN3 binding motif (identified by CAST-ing) in 2 kilobases of regulatory sequence. Up-regulated putative downstream targets included genes contributing to growth (c-Met-related tyrosine kinase (MST1R), MEK2; the guanine nucleotide exchanger RasGRP2, insulin-like growth factor-2, integrin beta 4), cell migration (MST1R), angiogenesis (vascular endothelial growth factor), and proteolysis (MMP26; cathepsin D; PRSS3 (protease serine 3)). We pursued integrin beta 4 (induced up to 6-fold) as a candidate target because it promotes breast cancer tumorigenicity and stimulates phosphatidyl 3-kinase implicated in colorectal cancer progression. ZKSCAN3 overexpression/silencing modulated integrin beta 4 expression, confirming the array analysis. Moreover, ZKSCAN3 bound to the integrin beta 4 promoter in vitro and in vivo, and the integrin beta 4-derived ZKSCAN3 motif fused upstream of a tk-Luc reporter conferred ZKSCAN3 sensitivity. Integrin beta 4 knockdown by short hairpin RNA countered ZKSCAN3-augmented anchorage-independent colony formation. We also demonstrate vascular endothelial growth factor as a direct ZKSCAN3 target. Thus, ZKSCAN3 regulates the expression of several genes favoring tumor progression including integrin beta 4.
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PMID:Unbiased screening for transcriptional targets of ZKSCAN3 identifies integrin beta 4 and vascular endothelial growth factor as downstream targets. 1894 Aug 3

We previously demonstrated that CD151 forms a functional complex with c-Met and integrin alpha3/alpha6 in human salivary gland cancer cells. In the current study, we investigated the involvement of CD151, c-Met, and integrin alpha3/alpha6 in the cellular morphogenesis of human breast cancer cells. Knockdown of CD151, integrin alpha3, or integrin alpha6 expression abolished branching morphogenesis. Decreased c-Met expression in these cells led to the formation of rudimentary networks and prevented their conversion. Furthermore, hepatocyte growth factor (HGF) promoted cellular morphogenesis by accelerating network reorganization. Immunoprecipitation revealed a specific association between CD151 and c-Met. The involvement of CD151 and integrin alpha3/alpha6 in HGF-dependent signaling was confirmed by the decreased Akt phosphorylation in cells lacking CD151, integrin alpha3, or integrin alpha6. Hence, the regulation of CD151 expression might contribute to changes in HGF/c-Met signaling and thereby modulate the phenotypic characteristics of cancer cells.
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PMID:CD151 regulates HGF-stimulated morphogenesis of human breast cancer cells. 1915 12

Understanding the signaling pathways that drive aggressive breast cancers is critical to the development of effective therapeutics. The oncogene MET is associated with decreased survival in breast cancer, yet the role that MET plays in the various breast cancer subtypes is unclear. We describe a knockin mouse with mutationally activated Met (Met(mut)) that develops a high incidence of diverse mammary tumors with basal characteristics, including metaplasia, absence of progesterone receptor and ERBB2 expression, and expression of cytokeratin 5. With gene expression and tissue microarray analysis, we show that high MET expression in human breast cancers significantly correlated with estrogen receptor negative/ERBB2 negative tumors and with basal breast cancers. Few treatment options exist for breast cancers of the basal or trastuzumab-resistant ERBB2 subtypes. We conclude from these studies that MET may play a critical role in the development of the most aggressive breast cancers and may be a rational therapeutic target.
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PMID:Met induces diverse mammary carcinomas in mice and is associated with human basal breast cancer. 1956 31

Although tamoxifen treatment is associated with improved survival in patients with estrogen receptor (ER)-positive breast tumors, resistance remains an important clinical obstacle. Signaling through growth factor signaling pathways, in particular through receptor tyrosine kinases, has been demonstrated to confer tamoxifen resistance in an estradiol-independent manner. The Ron receptor tyrosine kinase, a member of the c-Met family of receptors, is expressed in a number of human epithelial tumors, and elevated expression of Ron is associated with poor prognosis in women with breast cancer. In this report, we evaluated the role of Ron receptor activation in conferring resistance to tamoxifen in human and murine breast cancer cell lines. Activation of Ron by its ligand, hepatocyte growth factor-like protein (HGFL) was associated with partial rescue from tamoxifen-induced growth inhibition in Ron-expressing cell lines. Western analysis revealed that treatment of the T47D human breast cancer cell line with tamoxifen and HGFL was associated with increased phosphorylation of mitogen-activated protein kinase (MAPK) 1/2 and phosphorylation of serine residue 118 of ER. Expression of ER-dependent genes was increased in cells treated with tamoxifen and HGFL by quantitative reverse transcription-polymerase chain reaction. All of these effects were inhibited by treatment with either a Ron-neutralizing antibody or a MEK1 inhibitor, suggesting the specificity of the effect to Ron, and the involvement of the MAPK 1/2 signaling pathway. In summary, these results illustrate a novel connection between the Ron receptor tyrosine kinase and an important mechanism of tamoxifen resistance in breast cancer.
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PMID:Ron receptor tyrosine kinase activation confers resistance to tamoxifen in breast cancer cell lines. 2068 59


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