Unknown,Transcriptomics,Genomics,Proteomics

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β-catenin signaling is a critical event in ErbB2-mediated mammary tumor progression.

ABSTRACT: Although ERBB2 amplification and overexpression is correlated with poor outcome in breast cancer, the molecular mechanisms underlying the aggressive nature of these tumors has not been fully elucidated. To investigate this further, we have used a transgenic mouse model of ErbB2-driven tumor progression (ErbB2KI model) that recapitulates clinically relevant events, including selective amplification of the core erbB2 amplicon. By comparing the transcriptional profiles of ErbB2KI mammary tumors and human ERBB2-positive breast cancers, we demonstrate that ErbB2KI tumors possess molecular features of the basal subtype of ERBB2-positive human breast cancer, including activation of canonical β-catenin signaling. Inhibition of β-catenin-dependent signaling in ErbB2KI-derived tumor cells using RNA interference impaired tumor initiation and metastasis. Furthermore, treatment of ErbB2KI or human ERBB2-overexpressing tumor cells with a selective β-catenin/CBP inhibitor significantly decreased proliferation and ErbB2 expression. Collectively, our data indicate that ERBB2-mediated breast cancer progression requires β-catenin signaling and can be therapeutically targeted by selective β-catenin/CBP inhibitors. Common reference design. 9 samples (including 2 normal tissue, 2 NIC tumors, and 5 KI tumor tissue samples) replicated twice as dye swaps, generating a total of 18 arrays.

ORGANISM(S): Mus musculus

SUBMITTER: Robert Lesurf

PROVIDER: E-GEOD-37954 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

β-Catenin signaling is a critical event in ErbB2-mediated mammary tumor progression.

Schade Babette B Lesurf Robert R Sanguin-Gendreau Virginie V Bui Tung T Deblois Geneviève G O'Toole Sandra A SA Millar Ewan K A EK Zardawi Sara J SJ Lopez-Knowles Elena E Sutherland Robert L RL Giguère Vincent V Kahn Michael M Hallett Michael M Muller William J WJ

Cancer research 20130529 14

Although ERBB2 amplification and overexpression is correlated with poor outcome in breast cancer, the molecular mechanisms underlying the aggressive nature of these tumors has not been fully elucidated. To investigate this further, we have used a transgenic mouse model of ErbB2-driven tumor progression (ErbB2(KI) model) that recapitulates clinically relevant events, including selective amplification of the core erbB2 amplicon. By comparing the transcriptional profiles of ErbB2(KI) mammary tumors ...[more]

PMID: 23720052

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Project description:Background: Glucocorticoids are important pharmaceutical agents in the treatment of acute lymphoblastic leukemia in children. Resistance or sensitivity to glucocorticoids is considered to be of crucial importance for disease prognosis. Prednisolone is a first-line chemotherapeutic agent in the treatment of acute lymphoblastic leukemia. Here, the effects of prednisolone on the resistant CCRF-CEM leukemic cell line were studied. Methods: Prednisolone’s cytotoxic and cell cycle effects were studied with flow cytometry. NF-κB translocation was studied with Western Blotting and differential gene expression was studied with cDNA microarrays. Results: Prednisolone exerted a delayed biphasic effect, necrotic at low doses and apoptotic at higher doses. At low doses, prednisolone exerted a pre-dominant mitogenic effect despite its induction on total cell death, while at higher doses, prednisolone’s mitogenic and cell death effects were counterbalanced. NF-κB was constitutively present in the nucleus. Early gene microarray analysis revealed 40 differentially expressed genes upon 4 hours of prednisolone’s exposure. Notable differences in gene regulation were observed between the lowest and the highest glucocorticoid doses. Prednisolone activated genes related to apoptosis/tumor suppression, cell cycle progression, metabolism and intra-/ extra-cellular signaling pathways. Conclusions: The mitogenic/biphasic effects of prednisolone are of clinical importance in the case of resistant leukemic cells. This approach might lead to the identification of gene candidates for future molecular drug targets in combination therapy with glucocorticoids, along with early markers for glucocorticoid resistance. Elucidation of the mechanisms of GC action may lead to identification of gene targets responsible for GC resistance. Key tools in this process are high-throughput technologies such as microarray-based gene expression analysis. For this purpose, the parental CCRF-CEM cell line was chosen as the system of study for the effects of prednisolone treatment. This is a T-cell leukemia cell line characterized by a mutation (L753F) on one GR gene allele that impairs ligand binding (Thompson and Johnson 2003). It is known that both the DNA and ligand binding domains of the GR are required in order to repress NF-κB transactivation (Wissink, van Heerde et al. 1997). Interestingly, concerning the question whether this mutation would affect GC resistance, it has been reported previously that both the GC-resistant as well as the GC-sensitive CCRF-CEM subclones express heterogeneous populations of the GR (GRwt/GRL753F) (Palmer and Harmon 1991; Powers, Hillmann et al. 1993). The CCRF-CEM cell line has been reported to be resistant to GCs, presumably due to the accumulation of more resistant variants after long periods of prolonged culture (Norman and Thompson 1977). It is possible that these cells are clonally inhomogeneous, as possibly the cells obtained in vivo by patients. Moreover, the large number of the CCRF-CEM subclone studies in the literature makes it difficult to choose an appropriate resistant cell model. In addition, the utilization of an in vitro system for this study offered reproducibility, an opportunity to closely examine intracellular signals and avoid interference from other in vivo-participating systems. Thus, the cell line used for this study was considered to be useful in studying GC action and resistance in leukemic cells. The aim of this work was to determine the cytotoxic, cell cycle phase distribution and early cancer-specific gene expression effects of prednisolone in CCRF-CEM cells, as an in vitro model of ALL resistance to glucocorticoids. The early gene expression profile allowed identification of genes initiating pivotal, early onset regulatory mechanisms activated by GC and excluded ensuing feedback responses and further downstream signals. Samples tested were in the form of a loop-design i.e. control vs. 10nM prednisolone (designated 0vs1) , 10nM prednisolone vs.700uM prednisolone (designated 1vs3) and control vs. 700uM prednisolone (designated 0vs3), the sum of the logarithms of the first two should equal the third. In other words if Rj,i is the ratio of the ith gene in the jth experiment then R0vs1,i+R1vs3,i=R0vs3,i. We tested this using a statistical test. We have applied an intensity-dependent z-score where the sum of the ratios was compared to the ratio of the third experiment. If the difference was significant genes, in a standard deviation threshold of ±1.5 in relative units, were rejected from further analysis (Kerr and Churchill 2001; Kerr and Churchill 2001; Altman and Hua 2006; Kerr and Churchill 2007).

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Dataset Information

β-catenin signaling is a critical event in ErbB2-mediated mammary tumor progression.

Publications

β-Catenin signaling is a critical event in ErbB2-mediated mammary tumor progression.

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