HER2 / Neu is amplified and overexpressed in a large proportion of human breast cancers, but the signaling pathways that contribute to tumor development and metastatic progression are not completely understood. Using gene expression data and pathway signatures we predicted a role for activator E2F transcription factors in Neu induced tumors. This was genetically tested by interbreeding Neu transgenics with knockouts of the three activator E2Fs. Loss of any E2F delayed Neu induced tumor onset. E2F1 loss accelerated tumor growth while E2F2 and E2F3 loss did not. Strikingly, it was observed that loss of E2F1 or E2F2 significantly reduced the metastatic capacity of the tumor and this was associated with a reduction in circulating tumor cells in the E2F2 knockout. Gene expression analysis between the tumors in the various E2F mutant backgrounds revealed that there was extensive compensation by other E2F family members in the individual knockouts, underscoring the importance of the E2Fs in HER2 / Neu induced tumors. Extension to HER2 positive human breast cancer revealed a number of HER2+ subtypes based on E2F activity with differences in relapse free survival times. Taken together these data demonstrate that the E2F transcription factors are integral to HER2+ tumor development and progression.
HER2/Neu tumorigenesis and metastasis is regulated by E2F activator transcription factors.
Specimen part
View SamplesLoss of E2F transcription factos alters metastatic capacity of MMTV-PyMT tumors.
Histological subtypes of mouse mammary tumors reveal conserved relationships to human cancers.
Disease
View SamplesWe used microarrays to futher characterize the effects of T58A mutation in Myc on mammary tumorigenesis.
A mouse model with T58A mutations in Myc reduces the dependence on KRas mutations and has similarities to claudin-low human breast cancer.
Specimen part
View SamplesAdvances in genomic signatures have begun to dissect breast cancer heterogeneity, and application of these signatures will allow the prediction of which pathways are important in tumor development. Here we used genomic signatures to predict involvement of specific E2F transcription factors in Myc-induced tumors. We genetically tested this prediction by interbreeding Myc transgenics with mice lacking various activator E2F alleles. Tumor latency decreased in the E2F1 mutant background and significantly increased in both the E2F2 and E2F3 mutants. Investigating the mechanism behind these changes revealed a reduction in apoptosis in the E2F1 knockout strain. E2F2 and E2F3 mutant backgrounds alleviated Myc effects on the mammary gland, reducing the susceptible tumor target population. Gene expression data from tumors revealed that the E2F2 knockout background resulted in fewer tumors with EMT, corresponding with a reduction in probability of Ras activation. In human breast cancer we found that a low probability of E2F2 pathway activation was associated with increased relapse-free survival time. Together these data illustrate the predictive utility of genomic signatures in deciphering the heterogeneity within breast cancer and illustrate the unique genetic requirements for individual E2Fs in mediating tumorigenesis in both mouse models and human breast cancer.
Prediction and genetic demonstration of a role for activator E2Fs in Myc-induced tumors.
Specimen part
View SamplesWe used microarrays to compare gene expression profiles between mouse mammary tumors initiated by Myc to those that have escaped Myc oncogene dependence.
Heterogeneity in MYC-induced mammary tumors contributes to escape from oncogene dependence.
Specimen part
View SamplesWe have used primary MEFs derived from wild type and E2F4 null mice growing asynchrounously in serum to generate a signature for E2F4 pathway activation. 10 wild type and 10 E2F4 null samples were each assayed using the Affymetrics Mouse Genome 430A 2.0 array.
Patterns of cell signaling pathway activation that characterize mammary development.
No sample metadata fields
View SamplesHuman cancers result from a complex series of genetic alterations resulting in heterogeneous disease states. Dissecting this heterogeneity is critical for understanding underlying mechanisms and providing opportunities for therapeutics matching the complexity. Mouse models of cancer have generally been employed to reduce this complexity and focus on the role of single genes. Nevertheless, our analysis of tumors arising in the MMTV-Myc model of mammary carcinogenesis reveals substantial heterogeneity, seen in both histological and expression phenotypes. One contribution to this heterogeneity is the substantial frequency of activating Ras mutations, the frequency of which can be changed by alterations in Myc. Additionally, we show that these Myc-induced mammary tumors exhibit even greater heterogeneity, revealed by distinct histological subtypes as well as distinct patterns of gene expression, than many other mouse models of tumorigenesis. Two of the major histological subtypes are characterized by differential patterns of cellular signaling pathways, including B-Catenin and Stat3 activities. We also demonstrate the predictive nature of this approach though examining metastatic potential. Together, these data reveal that a combination of histological and genomic analyses can uncover substantial heterogeneity in mammary tumor formation and therefore highlight aspects of tumor phenotype not evident in the population as a whole.
Genetic heterogeneity of Myc-induced mammary tumors reflecting diverse phenotypes including metastatic potential.
No sample metadata fields
View SamplesThe Fra-1 transcription factor promotes tumor cell growth, invasion and metastasis. While characterizing five breast cancer cell lines derived from primary human breast tumors, we identified BRC-31 as a novel basal-like cell model that expresses elevated Fra-1 levels. BRC-31 cells display elevated FAK, SRC and ERK2 phosphorylation relative to luminal breast cancer models. Inhibition of this signaling axis, through the use of pharmacological inhibitors, reduces the phosphorylation and stabilization of Fra-1. Elevated integrin V3 expression in these cells suggested that integrin receptors might activate this FAK-SRC-ERK2 signaling axis to enhance Fra-1 phosphorylation. These cells also express high levels of uPAR, a GPI-anchored receptor that has been shown to enhance integrin-mediated signaling initiated by Vitronectin engagement. Transient knockdown of uPAR in BRC31 cells grown on Vitronectin reduces Fra-1 phosphorylation and stabilization and uPAR and Fra-1 are required for Vitronectin-induced cell invasion. In clinical samples, a molecular component signature consisting of Vitronectin-uPAR-uPA-Fra-1 predicts poor overall survival in patients with breast cancer and correlates with a Fra-1 transcriptional signature. Taken together, we have identified a novel-signaling axis that leads to phosphorylation and stabilization of Fra-1, a transcription factor that is emerging as an important modulator of breast cancer progression and metastasis.
Integrin-uPAR signaling leads to FRA-1 phosphorylation and enhanced breast cancer invasion.
Age, Disease, Disease stage
View SamplesIn this study, we used conditional knockout and gene expression approaches to understand global molecular and transciptional changes due to ablation of each integrin subunit.
Functional Redundancy between β1 and β3 Integrin in Activating the IR/Akt/mTORC1 Signaling Axis to Promote ErbB2-Driven Breast Cancer.
Specimen part
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Anchorage-independent cell growth signature identifies tumors with metastatic potential.
Specimen part, Cell line
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