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  • 1
    In: Molecular and Cellular Biology, Informa UK Limited, Vol. 26, No. 3 ( 2006-02-01), p. 777-788
    Type of Medium: Online Resource
    ISSN: 1098-5549
    Language: English
    Publisher: Informa UK Limited
    Publication Date: 2006
    detail.hit.zdb_id: 1474919-1
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  • 2
    In: Neoplasia, Elsevier BV, Vol. 15, No. 7 ( 2013-07), p. 848-IN45
    Type of Medium: Online Resource
    ISSN: 1476-5586
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2013
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  • 3
    In: Blood, American Society of Hematology, Vol. 114, No. 22 ( 2009-11-20), p. 470-470
    Abstract: Abstract 470 Introduction: Specialized microenvironments, or niches, of the bone marrow (BM) maintain and regulate physiological haematopoietic stem/progenitor cells and have been implicated as areas of preferential engraftment and ‘sanctuary sites' for leukaemic cells and metastasizing cells of solid tumours. The cellular and molecular factors that comprise the BM vascular niche have not been well described. Megakaryocytes (MKs) reside in close association with the BM sinusoidal endothelium. The aim of this study was to investigate whether MKs play a role in the homing and engraftment of malignant cells in the BM. Methods: C57Bl/6 wild type and thrombopoietin (TPO)-/- mice (which have 〈 10% of the normal number of MKs and platelets) received flank or tail vein injections of the syngeneic B16-F10 melanoma or EL4 lymphoma cell lines fluorescently labelled with mCherry or GFP. The MK-vascular niche was examined using citrulline, MECA32, and TSP1 immunostaining. MKs were cultured from the Lin-Sca1+cKit+-enriched fraction of BM cells from flushed femurs and tibias, using 50ng/ml TPO + 20ng/ml SCF. Costar transwell co-culture plates and Neuroprobe chemotaxis chambers were used; cellular proliferation was assessed using the CellTitre MTS assay. RNA was extracted from flushed BM cells and in vitro cell cultures using Qiagen RNeasy columns/Trizol and gene expression was analyzed by RT-qPCR. Results: In wild type mice, the majority of BM sinusoids were surrounded by one or more large MKs forming the MK-vascular niche, with MKs tightly abutting the vascular endothelium. In TPO-/- mice, MKs were largely absent from the BM, blood vessels appeared more tortuous and the mean vessel diameter in the BM was significantly larger than in wild type mice (P 〈 0.01). Expression of the angiogenic regulatory proteins platelet factor 4 (PF4) and thrombospondin 1 (TSP1) was markedly lower in BM from TPO-/- mice than wild type; expression of VEGF and TGFb was also reduced. Together these findings suggest that MKs support the integrity of the vascular niche and that homeostasis of the niche may be disrupted in the absence of MKs. Wild type mice injected with either B16-F10 melanoma or EL4 lymphoma had increased numbers of MKs and a larger mean vessel diameter. Although there was no increase in platelet count, the mean platelet volume was significantly increased by day 18 (p=0.002), suggesting increased thrombopoiesis. Furthermore, there was a linear decrease in PF4 in response to tumour, reaching a 3-fold reduction by late-stage tumour growth. This finding was consistent with the increase in MK-vascular niches as PF4 normally acts as an autocrine inhibitor of megakaryopoiesis and inhibits endothelial cell proliferation and migration. Consistent with a modulatory effect of MKs and/or the MK-vascular niche on tumour phenotype, tumour growth in TPO-/- mice was markedly retarded and there was reduced metastasis to the BM and lung. To investigate the mechanism of these effects, MK-conditioned medium (MCM) was added to in vitro cultures of B16 cells. MCM significantly enhanced the proliferation rate of B16 melanoma cells (P 〈 0.001). Further, MCM was highly chemotactic for B16 cells (P 〈 0.001). This effect was found to be mediated by pertussis toxin-sensitive Gi-protein receptors and reduced but not entirely abrogated in the absence of TSP1 (using MCM generated from TSP1-/- mice). To investigate the interactions between tumour cells and MKs, MKs were cocultured with B16 cells. Coculture increased MK expression of proangiogenic factors VEGF and TGFb while cocultured B16 cells displayed increased expression of alpha integrins, a4, a5 and a6. Moreover, coculturing B16 cells with MKs prior to tail vein injection enhanced tumour cell engraftment in the lung. A pilot study of BM trephine biopsies from 8 patients with carcinoma (breast, lung, prostate, bladder and kidney) supported these preclinical findings. MKs in 3/3 patients with BM metastasis and 3/5 patients without BM metastasis showed a variable excess of MKs, some in loose clusters, with abnormal morphology and localization. Conclusions: These findings suggest that MKs contribute to the integrity and functionality of the BM vascular niche in homeostasis and in malignancy, and that cellular/molecular cross-talk between MKs and tumour cells at the vascular niche may promote metastasis. Targeting these interactions may be a useful as adjunctive therapy to prevent dissemination of cancer to the BM. Disclosures: No relevant conflicts of interest to declare.
    Type of Medium: Online Resource
    ISSN: 0006-4971 , 1528-0020
    RVK:
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    Language: English
    Publisher: American Society of Hematology
    Publication Date: 2009
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  • 4
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2011
    In:  Cancer Research Vol. 71, No. 8_Supplement ( 2011-04-15), p. 546-546
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 71, No. 8_Supplement ( 2011-04-15), p. 546-546
    Abstract: Background: Of patients with breast cancer, an estimated 40 percent relapse and develop metastatic disease with bone as a preferred site of metastases. Radiation therapy is used frequently to treat bone metastases for palliation of symptoms and to improve local control. Advances in the field of radiation oncology such as image-guided and intensity-modulated radiation therapy (IGRT/IMRT) permit the delivery of high-dose radiation to bone metastases. The tumor stroma and bone marrow-derived cells have been shown to impact the response to irradiation, potentially via radiation-induced recruitment of bone marrow-derived cells and mesenchymal stem cells. To date, little is known about changes in the bone marrow and tumor microenvironment following high-dose irradiation. Using a murine model of metastatic breast cancer, we sought to investigate the effect of local high-dose irradiation on the irradiated, non-irradiated tumor microenvironments, and on the pattern of circulating hematopoietic, endothelial progenitor and mesenchymal stem cells. Methods: The metastatic murine mammary tumor cell line, 4T1, was engineered to express GFP and luciferase for in vitro and in vivo detection of tumor cells. These cells were injected into the bilateral tibias of BALB/c mice. Five days following intra-tibial injection, animals received either high-dose irradiation or sham irradiation to the right hind limb. Growth and progression of bone and lung metastases were monitored by in vivo bioluminescence. Blood was assayed for circulating myeloid-derived suppressor cells (MDSC), endothelial progenitor cells (EPC), and mesenchymal stem cells (MSC) at several time points following irradiation. Results: Intra-tibial injection of 4T1 cells resulted in rapid tumor growth and development of pulmonary metastases. High-dose irradiation (20Gy) resulted in a significant reduction in the irradiated tumor size without a significant change in the size of contralateral non-irradiated tumor, as evident by bioluminescent imaging. Pulmonary metastases in irradiated animals were hemorrhagic as compared to non-irradiated animals. Irradiation resulted in increased macrophage recruitment to the irradiated, but not the non-irradiated tumor. As compared to control mice and irradiated non-tumor bearing mice, animals with 4T1 intra-tibial tumors have increased numbers of circulating MDSC (CD11b+/Gr1+), EPC (CD144+/VEGFR2+), and MSC (CD105+/CD29+). Conclusions: Here we introduce a model of breast cancer bone metastasis that may be utilized to study the effects of high-dose irradiation. Irradiation results in changes in immune cell composition at both the local and systemic levels. Ongoing studies will address the specific immune cell subtypes present in irradiated versus non-irradiated bone tumors and the corresponding pulmonary metastases. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 546. doi:10.1158/1538-7445.AM2011-546
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
    RVK:
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    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2011
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  • 5
    Online Resource
    Online Resource
    American Association for Cancer Research (AACR) ; 2013
    In:  Cancer Research Vol. 73, No. 8_Supplement ( 2013-04-15), p. 4585-4585
    In: Cancer Research, American Association for Cancer Research (AACR), Vol. 73, No. 8_Supplement ( 2013-04-15), p. 4585-4585
    Abstract: At the time of a cancer diagnosis, most patients have localized tumors. Despite elaborate staging schemas for each cancer type in an attempt to stratify patients, the vast majority of patients that die will do so from metastatic disease. We hypothesized that surgery augments the already ongoing activation and mobilization of bone marrow-derived progenitor cells that are critical to colonizing tumor cells at distant sites. These bone marrow-derived cells, by inducing a local inflamed tumor microenvironment, provide survival signals to these seeding tumor cells. Our data show increased metastatic burden in the lung after surgical resection of the primary tumor using two murine cancer models, B16 melanoma and E0771 breast carcinoma. In these models, we also show a surge in hematopoietic and endothelial progenitor cells in the hours and days immediately following resection of the primary tumor, which is not similarly observed in control mice, where surgery was performed in the absence of the primary tumor. We also confirmed that a factor specific to the plasma of the tumor-bearing mice is responsible for this mobilization by using in vitro migration assays, whereby plasma from tumor-bearing mice and surgically resected mice induced an increased migration of lineage negative bone marrow cells compared to the plasma of wild type mice. We confirmed increased levels of MCP-1 and MCSF, both known to mobilize progenitor cells, in the plasma of mice with surgical resection. Additionally, targeting these bone marrow derived hematopoietic and endothelial progenitor cells with Pazopanib prevents the surge in bone marrow-derived cells into the circulation, abolishes the enhanced metastatic spread in mice undergoing surgical resection of the primary tumor, and provides a significant prolongation of survival. Finally, we correlated these data to a cohort of breast cancer patients where circulating levels of progenitor cells were analyzed at time points before and after surgery, which confirmed the mobilization of progenitor cells with surgery. Together, these results provide evidence for the increased risk of metastatic spread after surgical resection of the primary tumor and suggest that blocking progenitor cell mobilization by adjuvant treatment during or immediately following surgery, the incidence of metastatic recurrence may be reduced. Citation Format: Selena R. Granitto, Amber Giles, Simon Lavotshkin, Daniel Rutigliano, David Lyden, Rosandra N. Kaplan. Breaking metastatic dormancy during surgical resection of a primary tumor and implications for treatment strategies. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4585. doi:10.1158/1538-7445.AM2013-4585
    Type of Medium: Online Resource
    ISSN: 0008-5472 , 1538-7445
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    RVK:
    Language: English
    Publisher: American Association for Cancer Research (AACR)
    Publication Date: 2013
    detail.hit.zdb_id: 2036785-5
    detail.hit.zdb_id: 1432-1
    detail.hit.zdb_id: 410466-3
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