Project description:A Myc transcriptional program that is independent of EMT drives a poor prognosis tumor-propagating phenotype in HER2+ breast cancer
Project description:The HER2 (ERBB2) and MYC genes are commonly amplified genes in breast cancer, yet little is known about their molecular and clinical interaction. Using a novel chimeric mammary transgenic approach and in vitro models, we demonstrate markedly increased self renewal and tumour propagating capability of cells transformed with Her2 and c-Myc. Co-expression of both oncogenes in cultured cells led to a pronounced activation of a c-Myc transcriptional signature and acquisition of a self renewing phenotype independent of an EMT programme or regulation of cancer stem cell markers. We show that HER2 and c-MYC are frequently co-amplified in a clinical breast cancer cohort and that co-amplification is strongly associated with aggressive clinical behaviour and poor outcome. Lastly, we show that in patients receiving adjuvant chemotherapy (but not targeted anti-HER2 therapy), MYC amplification is associated with a poor outcome in HER2+ breast cancer patients. These findings demonstrate the importance of molecular context in oncogenic transformation and acquisition of a malignant stem-like phenotype and have important diagnostic and therapeutic consequences for the clinical management of HER2+ breast cancer. Gene expression analysis of Her2, Myc, and Her2 + Myc over expression on MCF10A cells, with MCF10A vector control comparison
Project description:The HER2 (ERBB2) and MYC genes are commonly amplified genes in breast cancer, yet little is known about their molecular and clinical interaction. Using a novel chimeric mammary transgenic approach and in vitro models, we demonstrate markedly increased self renewal and tumour propagating capability of cells transformed with Her2 and c-Myc. Co-expression of both oncogenes in cultured cells led to a pronounced activation of a c-Myc transcriptional signature and acquisition of a self renewing phenotype independent of an EMT programme or regulation of cancer stem cell markers. We show that HER2 and c-MYC are frequently co-amplified in a clinical breast cancer cohort and that co-amplification is strongly associated with aggressive clinical behaviour and poor outcome. Lastly, we show that in patients receiving adjuvant chemotherapy (but not targeted anti-HER2 therapy), MYC amplification is associated with a poor outcome in HER2+ breast cancer patients. These findings demonstrate the importance of molecular context in oncogenic transformation and acquisition of a malignant stem-like phenotype and have important diagnostic and therapeutic consequences for the clinical management of HER2+ breast cancer.
Project description:The transcription factor MYC is overexpressed in most cancers, where it drives multiple hallmarks of cancer progression. MYC is known to promote oncogenic transcription by binding to active promoters. In addition, MYC has also been shown to invade distal enhancers when expressed at oncogenic levels, but this enhancer binding has been proposed to have low gene-regulatory potential. Here, we demonstrate that MYC enhancer binding directly promotes cancer type-specific gene programs predictive of poor patient prognosis. MYC induces transcription of enhancer RNA through recruitment of RNAPII, rather than regulating RNAPII pause-release as is the case at promoters. This is mediated by MYC-induced H3K9 demethylation by KDM3A and acetylation by GCN5, leading to enhancer-specific BRD4 recruitment through its bromodomains, which facilitates RNAPII recruitment. Thus, we propose that MYC drives prognostic cancer type-specific gene programs by promoting RNAPII recruitment to enhancers through induction of an epigenetic switch.
Project description:Basal-like breast carcinoma is characterized by the expression of basal/myoepithelial markers, undifferentiated phenotype, highly aggressive behaviour and a frequent triple negative status (ESR-, PR-, Her2neu-). We have previously shown that epithelial-mesenchymal transition (EMT) occurs in basal-like breast tumours and identified Lysyl- Oxidase-Like 2 (LOXL2) as an EMT player and a poor prognosis marker in squamous cell carcinomas. We now show that LOXL2 mRNA is overexpressed in basal-like human breast carcinomas. Identification of new molecular markers in basal breast carcinomas 58 (IDC) infiltrative breast ductal carcinoma samples (Grade 3)
Project description:When making treatment decisions, oncologists often stratify breast cancers into a low-risk group (ER+, low grade); an intermediate-risk group (ER+, high grade); and a high-risk group that includes Her2+ and triple-negative (ER-/PR-/Her2-) tumors. None of the currently available gene signatures correlates to this clinical classification. We aimed to develop a test that is practical for the oncologists, that offers both molecular characterization of BCs, and improved prediction of prognosis and treatment response. We investigated the molecular basis of such clinical practice by grouping Her2+ and triple-negative breast cancers together during clustering analyses on the genome-wide gene expression profiles of our training cohort, mostly derived from fine needle aspiration biopsies (FNABs) of 149 consecutive evaluable Breast cancers. The analyses consistently divided these tumors into a three-cluster pattern, similar to clinical risk-stratification groups, that was reproducible in published microarray databases (n=2487) annotated with clinical outcomes. The clinicopathologic parameters of each of these three molecular groups were also similar to clinical classification. The low-risk group had good outcomes and benefited from endocrine therapy. Both intermediate- and high-risk groups had poor outcomes and were resistant to endocrine therapy. The latter demonstrated the highest rate of complete pathological response to neoadjuvant chemotherapy; the highest activities in MYC, E2F1, Ras, β-Catenin and IFN-γ pathways; and poor prognosis predicted by 14 independent prognostic signatures. Based on a multivariate analysis, this new gene signature, termed ClinicoMolecular Triad Classification, predicted recurrence and treatment response better than all pathologic parameters and other prognostic signatures. 149 invasive breast cancers from the 172 specimens contained 161 tumors were used in this study. Expression data of the 11 tumors with replicate was separately combined before analysis.
Project description:Epithelial-mesenchymal transition (EMT) is a diverse and dynamic biological process which is involved in cancer progression. It is important for carcinoma cells during invasion and metastasis. EMT has been in the spotlight for cancer cells to disseminate to distant organs by gaining partial EMT phenotype. Cancer cells with partial EMT are believed to be more cancerogenic/invasive than cells that have undergone complete EMT. The proteomic changes that occur following EMT in breast epithelial cells and how these relate to changes in cellular metabolism are incompletely understood. To study metabolic reprogramming in different mesenchymal states, we analyzed proteomic changes following EMT in the breast epithelial cell model D492, with single-shot LFQ supported by SILAC proteomic approach. The D492 EMT cell model contains three isogenic cell lines: epithelial D492 cells, mesenchymal D492M cells, and partial mesenchymal, HER2 overexpressing, tumorigenic D492HER2 cells. Proteomic analysis positioned the D492 and D492M cells as basal-like while D492HER2 as claudin-low. Further comparison of the non-tumorigenic D492 and D492M cells to tumorigenic D492HER2 differentiated the metabolic EMT markers of migration from those of invasion. Among these were markers of glycan metabolism. We identified glutamine-fructose-6-phosphate transaminase [isomerizing] 2 (GFPT2) as the top dysregulated enzyme in glycan metabolism and found increased GFPT2 expression was a characteristic of claudin-low breast cancer. siRNA knockdown of GFPT2 influenced both cell growth and invasion in vitro and was accompanied by lowered flux through the hexosamine biosynthesis pathway (HBP). Knockdown of GFPT2 decreased cystathionine and sulfide:quinone oxidoreductase (SQOR) in the transsulfuration pathway which regulates H2S production and mitochondrial homeostasis. Moreover, GFPT2 expression was regulated by the level of reduced glutathione (GSH) and suppressed by the oxidative stress regulator, GSK3-β. Our results demonstrate that GFPT2 is a marker for oxidative stress. It is upregulated and controls growth and invasion in the D492 EMT model and is associated with claudin-low and poor prognosis in breast cancer.
Project description:Epithelial-mesenchymal transition (EMT) is a diverse and dynamic biological process which is involved in cancer progression. It is important for carcinoma cells during invasion and metastasis. EMT has been in the spotlight for cancer cells to disseminate to distant organs by gaining partial EMT phenotype. Cancer cells with partial EMT are believed to be more cancerogenic/invasive than cells that have undergone complete EMT. The proteomic changes that occur following EMT in breast epithelial cells and how these relate to changes in cellular metabolism are incompletely understood. To study metabolic reprogramming in different mesenchymal states, we analyzed proteomic changes following EMT in the breast epithelial cell model D492, with single-shot LFQ supported by SILAC proteomic approach. The D492 EMT cell model contains three isogenic cell lines: epithelial D492 cells, mesenchymal D492M cells, and partial mesenchymal, HER2 overexpressing, tumorigenic D492HER2 cells. Proteomic analysis positioned the D492 and D492M cells as basal-like while D492HER2 as claudin-low. Further comparison of the non-tumorigenic D492 and D492M cells to tumorigenic D492HER2 differentiated the metabolic EMT markers of migration from those of invasion. Among these were markers of glycan metabolism. We identified glutamine-fructose-6-phosphate transaminase [isomerizing] 2 (GFPT2) as the top dysregulated enzyme in glycan metabolism and found increased GFPT2 expression was a characteristic of claudin-low breast cancer. siRNA knockdown of GFPT2 influenced both cell growth and invasion in vitro and was accompanied by lowered flux through the hexosamine biosynthesis pathway (HBP). Knockdown of GFPT2 decreased cystathionine and sulfide:quinone oxidoreductase (SQOR) in the transsulfuration pathway which regulates H2S production and mitochondrial homeostasis. Moreover, GFPT2 expression was regulated by the level of reduced glutathione (GSH) and suppressed by the oxidative stress regulator, GSK3-β. Our results demonstrate that GFPT2 is a marker for oxidative stress. It is upregulated and controls growth and invasion in the D492 EMT model and is associated with claudin-low and poor prognosis in breast cancer.
Project description:Purpose HER2 gene amplification or protein overexpression (HER2+) defines a clinically challenging subgroup of breast cancer with variable prognosis and response to therapy. We aimed to investigate the heterogeneous biological appearance and clinical behavior of HER2+ tumors using molecular profiling. Materials and Methods Hierarchical clustering of gene expression data from 58 HER2-amplified tumors of various stage, histological grade and estrogen receptor (ER) status was used to construct a HER2-derived prognostic predictor that was further evaluated in several large independent breast cancer data sets. Results Unsupervised analysis identified three subtypes of HER2+ tumors with mixed stage, histological grade and ER-status. One subtype had a significantly worse clinical outcome. A prognostic predictor was created based on differentially expressed genes between the subtype with worse outcome and the other subtypes. The predictor was able to define patient groups with better and worse outcome in HER2+ breast cancer across multiple independent breast cancer data sets and identify a sizable HER2+ group with long disease-free survival and low mortality. Significant correlation to prognosis was also observed in basal-like, ER−, lymph node positive or high-grade tumors, irrespective of HER2-status. The predictor included genes associated to immune response, tumor invasion and metastasis. Conclusion The HER2-derived prognostic predictor provides further insight into the heterogeneous biology of HER2+ tumors and may become useful for improved selection of patients that need additional treatment with new drugs targeting the HER2 pathway. Array comparative genomic hybridization (aCGH) identified 58 breast tumors with amplification of HER2 from a larger cohort of approx 500 tumors breast. Global gene expression profiles were obtained using 70-mer oligonucleotide microarrays. Unsupervised hierarchical clustering of the 58 tumors, using Pearson correlation and complete linkage, identified three main clusters. One cluster showed significantly poorer clinical outcome. Significance of microarray (SAM) analysis was performed to identify 158 genes separating the poor outcome cluster compared to the other two clusters. Gene expression centroids, based on the 158 genes, were created for each cluster for validation in independent breast cancer data sets.
Project description:Recently, several research groups have identified the mesenchymal subtype of serous OvCa on the basis of transcriptome data and its potential correlation with poor prognosis. We set out to define the regulatory mechanisms underlying the distinct gene expression profiles of serous OvCa using a network-based approach involving multiple molecular modalities such as gene expression and microRNA (miR) expression. Our study demonstrated that the mir-508-3p presented as the most powerful determinant of mesenchymal subtype-specific gene expression, tuning the majority of genes differentially expressed in the poor prognosis subtype, including genes associated with the epithelial–mesenchymal transition (EMT) program. Consequent functional experiments illustrate that miR-508-3p inhibition promoted EMT process, in vitro cell migration and invasion, and in vivo cancer metastasis.