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: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:The aberrant overexpression of mucin 1 (MUC1) and human epidermal growth factor receptor 2 (HER2) are often observed in breast cancer. However, the role of concomitant of MUC1/HERR2 in the development of breast cancer has not been fully illustrated. Following analysis public microarray datasets that revealed a correlation of double positive of MUC1 and HER2 to a worse clinical outcome, we generated a mouse model overexpressing both Her2 and MUC1 cytoplasmic domain (MUC1-CD) to investigate their interaction in mammary carcinogenesis. Coexpression of Her2 and MUC1-CD confers growth advantage and promotes the development of spontaneous mammary tumors. Genomic analysis uncovers that enforced expression of MUC1-CD and Her2 induces mammary tumor lineage plasticity which is supported by gene reprogramming and mammary stem cell enrichment. With gain- and loss-of function strategies, we show that coexpression of Her2 and MUC1-CD was associated with down-regulation of TCA cycle genes in tumors. Importantly, the reduction of TCA cycle genes induced by MUC1-CD is is significantly connected to the poor prognosis in HER2+ breast cancer patients. In addition, MUC1 augments Her2 signaling pathway by inducing Her2/Egfr dimerization. These findings collectively demonstrate the vital role of MUC1-CD/Her2 collaboration in shaping mammary tumor landscape and highlight the prognostic and therapeutic implication of MUC1 in patients with Her2+ breast cancer.
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: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.
Project description:We identified a 17-gene Her2-enriched tumor initiating cell (HTIC) signature in MMTV-Her2/Neu mouse mammary TICs. Here, we show that patients with HTICS+ HER2+:ERα− tumors are more likely to achieve a pathologic complete response to trastuzumab-based neoadjuvant chemotherapy compared with HER2+:ER+ tumors.
Project description:HER2 is a tyrosine kinase receptor causally involved in cancer. A subgroup of breast cancer patients with particularly poor clinical outcome expresses a heterogeneous collection of HER2 carboxy-terminal fragments (CTFs). However, since the CTFs lack the extracellular domain that drives dimerization and subsequent activation of full-length HER2, they are in principle expected to be inactive. Here we present evidence that at low expression levels one of these fragments, 611-CTF, activated multiple signaling pathways because of its unanticipated ability to constitutively homodimerize. A transcriptomic analysis revealed that 611-CTF specifically controlled the expression of genes that we found correlated with poor prognosis in breast cancer. Among the 611-CTF-regulated genes were several that previously have been linked to metastasis, including MET, EPHA2, MMP1, IL11, ANGPTL4 and different Integrins. Transgenic mice overexpressing HER2 in the mammary gland develop tumors only after acquisition of activating mutations in the transgene. In contrast, we show that expression of 611-CTF led to development of aggressive and invasive mammary tumors without the need for mutations. These results demonstrate that 611-CTF is a potent oncogene capable of promoting mammary tumor progression and metastasis. Affymetrix Gene Array expression study, using MCF7/tet-off clones stably transfected with vectors encoding HER2 and different truncated forms of the receptor, were used to elucidate the activity of the various protein isoforms. MCF7 clones were selected, maintain and expanded in the presence of doxycycline to avoid expression of the HER2 receptor isoforms. The experiments were started by seeding equal numbers of cells in two dishes, one with and one without doxycycline. 15 or 60 hours later total RNA was isolated in parallel from the two dishes. In the dishes without doxycycline the cloned HER2 isoforms were expressed from a CMV promoter. In total 50 arrays were included in the analysis. For key clones and time points biological replicates were included.