Recent efforts have uncovered immense transcriptional and ontogenetic diversity among tissue-resident macrophages, each with their own transcriptional profile endowing the cell with its tissue-specific functions. However, it is currently unknown whether the origins of different macrophage populations may affect their roles in malignancy. Given potential artifacts associated with irradiation-based lineage tracing, it remains unclear if bone marrow-derived macrophages (BMDM) are even present in tumors of the brain, a tissue where there is no homeostatic involvement of peripherally-derived myeloid cells. Here, we employed multiple models of murine brain malignancy and genetic lineage tracing models to demonstrate that BMDM are indeed abundant in primary and metastatic brain tumors. Transcriptional profiling of tumor-associated BMDM and resident microglia showed that these cells acquire substantially different gene expression profiles. Our data suggest that transcriptional networks in each cell population are associated with tumor-mediated education, yet are also influenced by chromatin landscapes established before tumor initiation. Furthermore, we demonstrate that microglia specifically repress Itga4 (CD49D), enabling its utility as a discriminatory marker between brain-resident microglia and peripherally-derived macrophages in both primary and metastatic disease in mouse and human. Overall design: Tumor associated microglia and macrophages were isolated from mouse glioma tumors. Samples are provided as matched microglia and macrophages from 3 tumors.
Macrophage Ontogeny Underlies Differences in Tumor-Specific Education in Brain Malignancies.
Specimen part, Cell line, Subject
View SamplesGlioblastoma multiforme (GBM), the most common and aggressive primary brain tumor in adults, can be divided into several molecular subtypes including proneural GBM. Most clinical strategies aimed at directly targeting glioma cells in these tumors have failed. A promising alternative is to target stromal cells in the brain microenvironment, such as tumor-associated microglia and macrophages (TAMs). Macrophages are dependent upon colony stimulating factor (CSF)-1 for differentiation and survival; therefore, we used an inhibitor of its receptor, CSF-1R, to target macrophages in a mouse proneural GBM model. CSF-1R inhibition dramatically increased survival in mice and regressed established GBMs. Tumor cell apoptosis was significantly increased, and proliferation and tumor grade markedly decreased. Surprisingly, TAMs were not depleted in tumors treated with the CSF-1R inhibitor. Instead, analysis of gene expression in TAMs isolated from treated tumors revealed a decrease in alternatively activated/ M2 macrophage markers, consistent with impaired tumor-promoting functions. These gene signatures were also associated with better survival specifically in the proneural subtype of patient gliomas. Collectively, these results establish macrophages as valid therapeutic targets in proneural gliomas, and highlight the clinical potential for CSF-1R inhibitors in GBM.
CSF-1R inhibition alters macrophage polarization and blocks glioma progression.
Sex, Specimen part
View SamplesTreatment with ALK tyrosine kinase inhibitors often elicits profound initial antitumor responses in ALK fusion-positive patients with lung adenocarcinoma. However, patients invariably develop acquired resistance to ALK inhibitors. In this study, we aimed to identify molecular events that limit the durable response to ALK inhibition using genetic and epigenetic approaches. To identify novel mechanisms of acquired resistance to ALK inhibitors, we established in vivo and in vitro models of acquired resistance to ceritinib and crizotinib using H3122 and H2228 cells. For in vivo model, mice with established H3122-derived tumors were treated with four doses of ceritinib (50mg/kg, 75mg/kg, 87.5mg/kg, 100mg/kg) to derive ceritinib-resistant tumors.
Enhancer Remodeling and MicroRNA Alterations Are Associated with Acquired Resistance to ALK Inhibitors.
Cell line
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