Project description:Breast cancer metastasis to bone is a critical determinant of long-term survival after treatment of primary tumors. We used a mouse model of spontaneous bone metastasis to determine new molecular mechanisms. Differential transcriptome comparisons of primary and metastatic tumor cells revealed that a substantial set of genes suppressed in bone metastases were highly enriched for promoter elements for the type I interferon (IFN) regulatory factor, Irf7, itself suppressed in mouse and human metastases. The critical function of the Irf7 pathway was demonstrated by restoration of exogenous Irf7 or systemic interferon administration, which significantly reduced bone metastases and prolonged metastasis-free survival. Using mice deficient in the type I receptor (Ifnar1-/-) or mature B, T and NK cell responses (NOD Scid IL-2rγ-/- mice), we demonstrated that Irf7-driven suppression of metastasis was reliant on IFN signaling to host immune cells. Metastasis suppression correlated with decreased accumulation of myeloid-derived suppressor cells and increased CD4++, CD8 T cells and NK cells in the peripheral blood and was reversed by depletion of CD8+ cells and NK cells. Clinical importance of our findings was demonstrated as increased primary tumor Irf7 expression predicted prolonged bone and lung metastasis-free survival. Thus we report for the first time, a novel innate immune pathway, intrinsic to breast cancer cells, whose suppression in turn restricts systemic immunosurveillance to enable metastasis. This pathway may constitute a novel therapeutic target for restricting breast cancer metastases. Microarrays were used to profile transcriptional alterations inherent in tumor cells growing in bone when compared to matched primary tumor cells in the 4T1.2 murine mammary tumor model. Primary and metastasized tumor were isolated from the same mouse with 4 independent biological replicates.
Project description:Many preclinical therapy studies have focused on a small number of well-described mouse allograft or human xenograft models that poorly represent the heterogeneity of human disease. Here we have assembled a panel of mouse mammary cell lines that metastasize in syngeneic mouse hosts and we have assessed gene expression programs in the untreated primary tumors with the goal of generating information that may be useful to the identification of biomarkers that predict response to therapeutic intervention. We used microarrays to assess global gene expression programs in primary tumors from 12 metastatic mouse mammary tumor models transplanted orthotopically into syngeneic, fully immunocompetent mouse hosts. The 12 tumor models used here are based on published cell lines that had been established from either spontaneous mammary tumors or from mammary tumors arising in genetically engineered mouse models. All cell lines were previously described to be metastatic. Cells were surgically implanted in the #4 mammary fat pads of syngeneic mice and primary tumors were harvested when they reached 0.5-1.0 cm diameter and snap-frozen for later RNA extraction. 4 independent tumors were collected for each of the 12 models.
Project description:Breast cancer metastasis to bone is a critical determinant of long-term survival after treatment of primary tumors. We used a mouse model of spontaneous bone metastasis to determine new molecular mechanisms. Differential transcriptome comparisons of primary and metastatic tumor cells revealed that a substantial set of genes suppressed in bone metastases were highly enriched for promoter elements for the type I interferon (IFN) regulatory factor, Irf7, itself suppressed in mouse and human metastases. The critical function of the Irf7 pathway was demonstrated by restoration of exogenous Irf7 or systemic interferon administration, which significantly reduced bone metastases and prolonged metastasis free survival. Using mice deficient in the type I receptor (Ifnar1-/-) or mature B, T and NK cell responses (NOD Scid IL-2rγ-/- mice) we demonstrated that Irf7-driven suppression of metastasis was reliant on IFN signaling to host immune cells. Metastasis suppression correlated with decreased accumulation of myeloid-derived suppressor cells and increased CD4++, CD8 T cells and NK cells in the peripheral blood and was reversed by depletion of CD8+ cells and NK cells. Clinical importance of our findings was demonstrated as increased primary tumor Irf7 expression predicted prolonged bone and lung metastasis-free survival. Thus we report for the first time, a novel innate immune pathway, intrinsic to breast cancer cells, whose suppression in turn restricts systemic immunosurveillance to enable metastasis. This pathway may constitute a novel therapeutic target for restricting breast cancer metastases. Comparison of basal gene expression in breast cancer 4T1.2 cell line stably transfected using the pMSCV retroviral expression vector system with IRF7 or the base vector. Three independent experiments were performed comparing the IRF7 expressing cells to the base vector cells
Project description:BMP4 is down-regulated in metastatic human and murine mammary tumours. Here we determined the effect of ectopic mouse Bmp4 re-expression on global gene expression patterns in orthotopic primary mammary tumours in syngeneic Balb/c mice. Breast cancer is a major cause of cancer related death in women, due to the development of metastatic disease in vital organs. Metastasis can be facilitated by tumor induced MDSC, which requires understanding. We have confirmed that BMP4 is a potent suppressor of breast cancer metastasis, but for potential clinical application, it is important to understand how BMP4 acts to suppress metastasis. Here, we report one mechanism by which BMP4 can inhibit metastasis. Mice bearing highly metastatic mammary tumors present with elevated numbers of myeloid derived suppressor cells (MDSC), the extent of which is markedly reduced upon exogenous BMP4 expression. Increased numbers of MDSC can also be induced directly by treatment with granulocyte-colony stimulating factor (G-CSF), leading to enhancement of metastasis. Both tumor-induced and G-CSF-induced MDSC can effectively suppress T cell activation and proliferation. BMP4 acts to reduce the expression and secretion of G-CSF through inhibition of NFkB activity in several human and mouse tumor lines. Since MDSC in breast cancer patients are correlated with poor prognosis, BMP4 treatment offers a potential new therapeutic strategy for progressive breast disease. Three 4T1.2 primary mammary tumours and three 4T1.2-Bmp4 primary mammary tumours were analyzed.
Project description:Many preclinical therapy studies have focused on a small number of well-described mouse allograft or human xenograft models that poorly represent the heterogeneity of human disease. Here we have assembled a panel of mouse mammary cell lines that metastasize in syngeneic mouse hosts and we have assessed gene expression programs in the untreated primary tumors with the goal of generating information that may be useful to the identification of biomarkers that predict response to therapeutic intervention. We used microarrays to assess global gene expression programs in primary tumors from 12 metastatic mouse mammary tumor models transplanted orthotopically into syngeneic, fully immunocompetent mouse hosts. The 12 tumor models used here are based on published cell lines that had been established from either spontaneous mammary tumors or from mammary tumors arising in genetically engineered mouse models. All cell lines were previously described to be metastatic.
Project description:Breast cancer brain metastasis remains largely incurable. While several mouse models have been developed to investigate the genes and mechanisms regulating breast cancer brain metastasis, these models often lack clinical relevance since they require the use of immune-compromised mice and/or are poorly metastatic to brain from the mammary gland. We describe the development and characterization of an aggressive brain metastatic variant of the 4T1 syngeneic model (4T1Br4) that spontaneously metastasises to lung, bone and brain but is selectively more metastatic to the brain from the mammary gland than parental 4T1 tumors. The 4T1Br4 model will provide a clinically relevant tool to evaluate novel therapies against brain metastasis.
Project description:The aim of this investigation was to study the consequences of interfering with soluble epoxide hydrolase (sEH) expression on tumor growth and metastasis in genetically modified animals that spontaneously generate tumors without the exogenous application of high concentrations of epoxide mediators or inhibitors. Therefore, breast cancer development was studied in mice expressing the polyoma middle T oncogene (PyMT) under the control of the mouse mammary tumor virus promoter, to induce spontaneous mammary tumors. To facilitate the study of endogenous sEH activity in tumor growth, PyMT mice were then crossed with sEH-/- mice to generate sEH-deficient mice that spontaneously generate breast tumors (so called PyMTsEH mice). For these analyses, primary tumors were removed from 20 week old mice.
Project description:MMTV-NeuNT transgenic mouse model harbors an activated form of Neu (NeuNT). Mice develop stochastically multifocal mammary adenocarcinomas that metastasize to the lung (Muller et al., 1988). MMTV-NeuNT mouse model exhibits both intravascular and parenchymal metastasis which provides a good tool to comprehensively study breast cancer metastasis. In this study, we investigated the role of tenascin C (TNC) in tumor progression using the a syngeneic orthotopic grafting mouse model. NT193 cell line was isolated from MMTV-NeuNT TNC WT tumor tissue. TNC expression in these cells was turned down through shRNA strategy, giving rise to NT193 shTNC cells and their respective control NT193 shcTNC. These cells were grafted orthotopically into syngeneic FVB mice either WT or KO for TNC. In FVB WT mice, NT193 shcTNC tissue was treated with AMD3100 (plerixafor) (Sigma, A5602) at 5 mg/kg/day by peritumoral injection for 2 weeks before processing with NT193 shcTNC and NT193 shTNC tissue receiving phosphate buffered saline as a control.
Project description:Metastatic disease remains one of the most urgent clinical challenges accounting for over 90% of cancer-related deaths. Yet, the identification of novel therapeutic targets to fight or prevent metastatic disease has been hampered by the limited availability of clinically relevant mouse models of metastasis formation. To address this caveat, we developed a novel preclinical mouse model of spontaneous metastatic breast cancer that recapitulates the key biological events of the metastatic cascade and mimics the clinical course of metastatic disease in humans. Exploiting the conditional K14cre;CdhF/F;Trp53F/F mouse model of de novo mammary tumor formation, we orthotopically transplanted K14cre;CdhF/F;Trp53F/F derived mouse invasive lobular carcinoma (mILC) fragments into mammary glands of wild-type syngeneic hosts. Once recipient mammary tumors were established, we mimicked the clinical setting and performed a mastectomy. Following surgery, recipient mice eventually succumbed to wide-spread clinically overt metastatic disease in lymph nodes, lungs and gastrointestinal tract. Using aCGH analyses, we explored the relationship between the genomic profiles of mammary donor tumors and paired recipient outgrowths and observed a strong correlation, indicating that the genomic profile of the parental K14cre;CdhF/F;Trp53F/F mILC is highly conserved in recipient mammary tumors. To investigate the genomic relationship between recipient mammary tumors and their metastases, we examined the correlation structure of genomic profiles derived from paired sets of primary tumors and metastases. Genomic profiles of clonally-related recipient mammary tumors were highly conserved in local and distant metastases, indicating that few genomic alterations occur during transition from a primary tumor to a distant site. To more thoroughly examine potential site-specific genomic alterations, we constructed so-called ‘delta-profiles’ by calculating the difference between the genomic profile of a recipient mammary tumor and its paired lymph node- and lung metastasis. Site-specific recurrent alterations were not observed in lymph node nor lung metastases. Taken together, these data show that genomic profiles of metastases are highly similar to those of parental recipient tumors and that, if changes occurred, they did not recur in different independent samples. We performed aCGH analyses on DNA isolated from K14cre;Cdh-/-;Trp53-/- derived donor mILCs (n=3) and their recipient mammary tumor outgrowths (n=10). Furthermore, we also analyzed genomic profiles derived from lung (n=10), tumor-draining (n=7) and distant lymph node metastases (n=5) isolated from the same recipient mice. DNA from each of these samples was hybridized against related donor splenic DNA.