Project description:The Epidermal Growth Factor Receptor 2 (ERBB2 or HER2) is amplified and overexpressed in approximately 20% of invasive breast cancers and is associated with metastasis and poor prognosis. Here we describe the role of a constitutively active splice variant of HER2 (Delta-HER2) in human mammary epithelial cells. Overexpression of Delta-HER2 in human mammary cells decreased apoptosis and increased proliferation and expression of epithelial-to-mesenchymal markers. It also induced invasion in three-dimensional cultures and promoted tumorigenicity and metastasis in vivo. In contrast, similar overexpression of wild-type HER2 failed to evoke the same effects. Unbiased protein-tyrosine phosphorylation profiling revealed a significant increase in phosphorylation of several key signaling proteins upon Delta-HER2 expression, some of which not previously shown to belong to the HER2 pathway. In addition, microarray analysis revealed the expression of a set of genes specifically associated with Delta-HER2 expression. We found those genes to be highly expressed in ER-negative, high grade and metastatic primary breast tumors. Altogether, these results provide new insights into the function of a tumorigenic splice variant of HER2 and the signaling cascade deriving from its activity RNA was extracted from MCF10A expressing empty vector, WT-HER2 or Delta-HER2 (n=3).
Project description:The Epidermal Growth Factor Receptor 2 (ERBB2 or HER2) is amplified and overexpressed in approximately 20% of invasive breast cancers and is associated with metastasis and poor prognosis. Here we describe the role of a constitutively active splice variant of HER2 (Delta-HER2) in human mammary epithelial cells. Overexpression of Delta-HER2 in human mammary cells decreased apoptosis and increased proliferation and expression of epithelial-to-mesenchymal markers. It also induced invasion in three-dimensional cultures and promoted tumorigenicity and metastasis in vivo. In contrast, similar overexpression of wild-type HER2 failed to evoke the same effects. Unbiased protein-tyrosine phosphorylation profiling revealed a significant increase in phosphorylation of several key signaling proteins upon Delta-HER2 expression, some of which not previously shown to belong to the HER2 pathway. In addition, microarray analysis revealed the expression of a set of genes specifically associated with Delta-HER2 expression. We found those genes to be highly expressed in ER-negative, high grade and metastatic primary breast tumors. Altogether, these results provide new insights into the function of a tumorigenic splice variant of HER2 and the signaling cascade deriving from its activity
Project description:d16HER2 is a splice variant of HER2 receptor characterized by a significant tumor aggressiveness. We derived primary tumor cell lines from spontaneous tumors grown in mice transgenic respectively for human d16 (MI6 and MI7 cell lines) and WT HER2 isoforms (WTHER2_1 and WTHER2_2). To analyze the molecular mechanisms underlying the higher tumorigenicity of d16HER2 than that of WTHER2, we conducted gene expression profiling analysis of these cell lines.
Project description:We studied cell lines derived from two transgenic mammary tumors driven by human HER2 that showed different dynamics of HER2 status. MamBo89 (HER2 stable) cell line displayed high and stable HER2 expression, which was maintained upon in vivo passages, whereas MamBo43 (HER2 labile) cell line gave rise to HER2-negative tumors, from which MamBo38 (HER2 loss) cell line was derived. MamBo cell lines were established from mammary tumors of FVBhuHER2 virgin female mice.
Project description:Purpose: There is an unmet clinical need for biomarkers to identify breast cancer patients who are at increased risk of developing brain metastases. The objective is to identify gene signatures and biological pathways associated with HER2+ brain metastasis. Experimental Design: Gene expression of 19 HER2+ breast cancer brain metastases was compared with HER2+ nonmetastatic primary tumors. Gene Set Enrichment Analysis was used to identify a signature, which was evaluated for correlation with BRCA1 mutation status and clinical outcome using published microarray datasets and for correlation with pharmacological inhibition by a PARP inhibitor and temozolomide using published microarray datasets of breast cancer cell lines. Results: A BRCA1 Deficient-Like (BD-L) gene signature is significantly correlated with HER2+ metastases in both our and an independent cohort. BD-L signature is enriched in BRCA1 mutation carrier primary tumors and HER2-/ER- sporadic tumors, but high values are found in a subset of ER+ and HER2+ tumors. Elevated BD-L signature in primary tumors is associated with increased risk of overall relapse, brain relapse, and decreased survival. The BD-L signature correlates with pharmacologic response to PARP inhibitor and temozolomide in two independent microarray datasets, and the signature outperformed four published gene signatures of BRCA1/2 deficiency. Conclusions: The BD-L signature is enriched in breast cancer brain metastases and identifies a subset of primary tumors with increased propensity for brain metastasis. Furthermore, this signature may serve as a biomarker to identify sporadic breast cancer patients who could benefit from a therapeutic combination of PARP inhibitor and temozolomide. Gene expression of 19 HER2+ human breast cancer brain metastases was compared with gene expression of 19 HER2+ nonmetastatic primary human breast tumors.
Project description:The tyrosine kinase receptors HER2 and HER3 play an important role in breast cancer. The HER2/HER3 heterodimer is a critical oncogenic unit associated with reduced relapse-free and decreased overall survival. We provide gene expression profile of the mammary epithelial cells MCF10A expressing HER2, HER3 or HER2/HER3 and grown in three-dimensional cultures for 15 days in the presence of heregulin, a known HER3-ligand that stabilizes and activates the HER2/HER3 heterodimer. The mammary epithelial cells MCF10A were transduced with retroviral vectors expressing HER2, HER3 or both. Cells from each group were grown for 15 days in three-dimensional cultures. At the end of the experiment, RNA was extracted for gene expression analysis.
Project description:HER2 (ERBB2) gene amplification and PIK3CA mutations often co-occur in breast cancer, and aberrant activation of the PI3K pathway has been implicated in resistance to HER2-directed therapies. We have created a mouse model of HER2-overexpressing (HER2+), PIK3CAH1047R-mutant breast cancer. Mice expressing both human HER2 and mutant PIK3CA in their mammary glands developed tumors with a significantly shorter latency compared to mice expressing either oncogene alone. By microarray analysis, HER2-driven tumors clustered with the luminal subtype, whereas HER2+PIK3CA and PIK3CA-driven tumors were associated with the claudin-low breast cancer subtype. In accordance, PIK3CA and HER2+PIK3CA tumors expressed elevated levels of EMT and stem cell markers, and cells from HER2+PIK3CA tumors more efficiently formed mammospheres, providing further evidence that activated PIK3CA may enrich for cancer stem cells. Finally, HER2+PIK3CA tumors are resistant to the HER2 antibody trastuzumab; resistance is partially reversed by the addition of a PI3K inhibitor. Taken together, these studies suggest that the co-expression of HER2 and PI3KH1047R in the mouse mammary gland accelerates the formation of aggressive, trastuzumab-resistant tumors. referenceXsample
Project description:The tumor immune microenvironment (TIME) is a critical determinant of therapeutic response. However, the mechanisms regulating its modulation are not fully understood. HER2D16, an oncogenic splice variant of the human epidermal growth factor receptor (HER2), has been implicated in breast cancer and other tumor types as a driver of tumorigenesis and metastasis. Nevertheless, the underlying mechanisms of HER2Δ16-mediated oncogenicity remain poorly understood. Here, we show that HER2∆16 expression is not exclusive to the clinically HER2+ subtype and is associated with a poor clinical outcome in breast cancer. To understand how HER2 variants modulate the tumor microenvironment, we generated transgenic mouse models expressing either proto-oncogenic HER2 or HER2D16 in the mammary epithelium. We found that HER2∆16 tumors are immune cold, characterized by low immune infiltrate and an altered cytokine profile. Using an epithelial cell surface proteomic approach, we identified ENPP1 as a functional regulator of the immune cold microenvironment. We generated a knock-in model of HER2Δ16 under the endogenous promoter to understand the role of ENPP1 in aggressive HER2+ breast cancer. Knockdown of ENPP1 in HER2Δ16-derived tumor cells resulted in decreased tumor growth that was correlated with increased T-cell infiltration. These findings suggest that HER2Δ16-dependent ENPP1 activation is associated with aggressive HER2+ breast cancer through its immune modulatory function. Our study provides a better understanding of the mechanisms underlying HER2Δ16-mediated oncogenicity and highlights ENPP1 as a potential therapeutic target in aggressive HER2+ breast cancer.
Project description:The tumor immune microenvironment (TIME) is a critical determinant of therapeutic response. However, the mechanisms regulating its modulation are not fully understood. HER2D16, an oncogenic splice variant of the human epidermal growth factor receptor (HER2), has been implicated in breast cancer and other tumor types as a driver of tumorigenesis and metastasis. Nevertheless, the underlying mechanisms of HER2Δ16-mediated oncogenicity remain poorly understood. Here, we show that HER2∆16 expression is not exclusive to the clinically HER2+ subtype and is associated with a poor clinical outcome in breast cancer. To understand how HER2 variants modulate the tumor microenvironment, we generated transgenic mouse models expressing either proto-oncogenic HER2 or HER2D16 in the mammary epithelium. We found that HER2∆16 tumors are immune cold, characterized by low immune infiltrate and an altered cytokine profile. Using an epithelial cell surface proteomic approach, we identified ENPP1 as a functional regulator of the immune cold microenvironment. We generated a knock-in model of HER2Δ16 under the endogenous promoter to understand the role of ENPP1 in aggressive HER2+ breast cancer. Knockdown of ENPP1 in HER2Δ16-derived tumor cells resulted in decreased tumor growth that was correlated with increased T-cell infiltration. These findings suggest that HER2Δ16-dependent ENPP1 activation is associated with aggressive HER2+ breast cancer through its immune modulatory function. Our study provides a better understanding of the mechanisms underlying HER2Δ16-mediated oncogenicity and highlights ENPP1 as a potential therapeutic target in aggressive HER2+ breast cancer.