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:Disruption of Estrogen Signaling Enhances Invasiveness of Breast Cancer Cells by Attenuating a HER2-independent Gene Repression Program
Project description:CdGAP/ARHGAP31 is a molecular target of TGFb-mediated EMT and required for Her2-positive breast cancer growth and metastasis Metastasis is the leading cause of death in breast cancer patients. The epithelial-to-mesenchymal transition (EMT) has a crucial role in metastasis and is highly critical for tumor cell dissemination. CdGAP/ARHGAP31 is highly expressed in breast cancer tissues and is associated with poor clinical outcome in breast cancer patients. CdGAP cooperates in a GAP-independent manner with the transcriptional repressor Zeb2 to function as a critical modulator of breast cancer through repression of E-cadherin transcription. In this study, we used a murine model of Her2+ breast cancer to investigate further the role of CdGAP in breast tumorigenesis. We found that CdGAP was essential for tumor formation and metastasis to the lungs in the Her2+ mouse breast cancer model. We determined that CdGAP is required for intravasation and growth at the metastatic sites. By using global gene expression approaches, we found that CdGAP depletion in Her2+ primary tumors was associated with an EMT signature, including a decreased expression of the metastatic factor claudin-2 and an increase in E-cadherin expression. In Her2+ breast cancer cells, CdGAP expression is positively regulated by the TGFb canonical pathway in a smad-dependent manner and regulates cell proliferation, migration, invasion, and adhesion. CdGAP was found to interact with the focal adhesion protein Talin and regulates focal adhesion dynamics in breast cancer cells. Collectively, CdGAP appears as a potential anti-metastatic target for the treatment of Her2+ breast cancer.
Project description:Systemic metabolic alterations associated with increased consumption of saturated fat and obesity are linked with increased risk of prostate cancer progression and mortality but the molecular underpinnings of this association are poorly understood. Furthermore, the mechanisms by which metabolic rewiring alters the prostate cancer epigenome, the effector arm of intra- and extra-cellular signals, is equally nebulous. Here, we demonstrate, in a murine prostate cancer model, that high-fat diet (HFD) enhances the MYC transcriptional program through metabolic alterations that favour histone H4K20 hypomethylation at the promoter regions of MYC regulated genes, leading to a HFD-dependent phenotype characterized by increased cellular proliferation and tumour burden. Importantly, these results are recapitulated in prostate cancer patients, where increased saturated fat intake (SFI), but not monounsaturated or polyunsaturated fat intake, is also associated with an enhanced MYC transcriptional signature. Additionally, the SFI-induced MYC signature independently predicts prostate cancer progression and death. Finally, a dietary intervention consisting of switching from a high-fat to control diet, greatly attenuates the MYC transcriptional program. Our findings suggest that in primary prostate cancer, dietary fat intake contributes to tumour progression by mimicking MYC over expression, setting the stage for therapeutic approaches involving changes to the diet.
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:Cultured cancer cells exhibit substantial phenotypic heterogeneity when measured in a variety of ways such as sensitivity to drugs or the capacity to grow under various conditions. Among these, the ability to exhibit anchorage-independent cell growth (colony forming capacity in semisolid media) has been considered to be fundamental in cancer biology because it has been connected with tumor cell aggressiveness in vivo such as tumorigenic and metastatic potentials, and also utilized as a marker for in vitro transformation. Although multiple genetic factors for anchorage-independence have been identified, the molecular basis for this capacity is still largely unknown. To investigate the molecular mechanisms underlying anchorage-independent cell growth, we have used genome-wide DNA microarray studies to develop an expression signature associated with this phenotype. Using this signature, we identify a program of activated mitochondrial biogenesis associated with the phenotype of anchorage-independent growth and importantly, we demonstrate that this phenotype predicts potential for metastasis in primary breast and lung tumors. Keywords: c-Myc or v-Src retroviral vector-infected immortalized mouse embryonic fibroblasts. Expression data of c-Myc and v-Src transformed MEFs was used to validate an expression signature generated from human cultured breast cancer cell lines with anchorage-independent growth ability.
Project description:The sequential accumulation of survival advantage traits – the cancer evolution hypothesis – implies that early detection and treatment of precancers can prevent cancer mortality. In practice, detection and treatment of breast precancer ductal carcinoma in situ (DCIS) has had minimal impact on reducing breast cancer mortality. The evolution of precancer is not inevitable, suggesting that inciting neoplastic events lead to different trajectories of progression. Here we visualize distinct tumor driver gene programs of lineage specification occurring at cancer initiation. Crainbow fluorescent barcoding of wild-type HER2, d16-HER2, and p95-HER2 enables whole-gland lineage tracing and single-cell reconstruction of the origin of HER2+ breast cancer. Molecular pathology and Crainbow lineage tracing provide genotype:phenotype modules and gene signatures predictive of cancer progression. WT-HER2 neoplasms were rare and proliferative d16-HER2 neoplasms eventually progressed to metastasis, and p95-HER2 induced rapidly invasive and metastatic carcinomas. p95-HER2 carcinomas originate without detectable in situ stages – termed here a minimally detectable “nascent lethal carcinoma”. This nascent lethal program biases the commitment of tumor stem cells toward a metaplastic epithelial-mesenchymal transition-like (EMT) lineage promoting microenvironmental remodeling. Overall, these data suggest that lethality programs begin at initiation, indicating that detection must be improved to identify the nascent lethal lesion.
Project description:Interleukin 6 (IL6) signaling has been associated with an aggressive and metastatic phenotype in multiple solid tumors including breast cancer, but its mechanism of action in mediating tumor progression and treatment response is not clear. By exploiting a clinically relevant intraductal xenograft model of estrogen receptor positive (ER+) breast cancer, we demonstrate that IL6 increases both primary tumor growth and distant metastases. By integrating pre-clinical models and clinical specimens, we show that signal transducer and activator of transcription 3 (STAT3) mediates IL6-induced activation of a metastatic gene program from enhancer-elements shared with ER and its pioneer factor FOXA1. Although IL6 activated STAT3 and ER/FOXA1 share cis-regulatory regions, STAT3 drives transcription independent of ER and FOXA1 function, and the IL6/STAT3 gene program is not influenced by ER-targeted therapies, decoupling these two important pathways. This demonstrates that ER/FOXA1 and IL6/STAT3 are two parallel, but independent actionable pathways controlling breast cancer progression.