Astrocytic trans-differentiation completes a multicellular paracrine feedback loop required for medulloblastoma tumor growth
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ABSTRACT: We report the application of RNA-sequencing technology for high-throughput profiling of tumor-associated microglia/macrophage (TAMs). First, we checked the purity of sample by qRT-PCR. We confirmed the high purity of TAMs with rare other cell type contamination. By profiling samples of TAMs purified from five individual medulloblastoma of mouse model, we find that TAMs maintain microglia gene signature even there are decrease of microglia genes and increase of macrophage genes. This study provides the evidence for the application of comprehensive gene profiling towards characterization of cellular origin of cell populations in tumor microenvironment.
Project description:The tumor microenvironment (TME) is critical for tumor progression. However, the establishment and function of the TME remain obscure because of its complex cellular composition. Using a mouse genetic system called mosaic analysis with double markers (MADMs), we delineated TME evolution at single-cell resolution in sonic hedgehog (SHH)-activated medulloblastomas that originate from unipotent granule neuron progenitors in the brain. First, we found that astrocytes within the TME (TuAstrocytes) were trans-differentiated from tumor granule neuron precursors (GNPs), which normally never differentiate into astrocytes. Second, we identified that TME-derived IGF1 promotes tumor progression. Third, we uncovered that insulin-like growth factor 1 (IGF1) is produced by tumor-associated microglia in response to interleukin-4 (IL-4) stimulation. Finally, we found that IL-4 is secreted by TuAstrocytes. Collectively, our studies reveal an evolutionary process that produces a multi-lateral network within the TME of medulloblastoma: a fraction of tumor cells trans-differentiate into TuAstrocytes, which, in turn, produce IL-4 that stimulates microglia to produce IGF1 to promote tumor progression.
Project description:We used RNA-sequencing technology for high-throughput profiling of tumor-derived astrocytes. Laser capture microdissection of individual cells was performed on an ArcturusXT LCM system (Applied Biosystems) with an infrared laser using CapSure HS LCM caps after optimization of laser power and duration. For each sample, 250 cells were microdissected per LCM cap and split into five 50-cell technical replicates (as a control, one replicate did not undergo reverse transcription) after elution from the cap. Reamplified cDNA (~500 bp 3’ ends) was purified away from primer concatemers by two rounds of purification with 0.7x volume of AMPure XP beads (Beckman) according to the manufacturer’s recommendations, and purified cDNA was quantified by Qubit assay (Life Technologies). For each sample, 1 ng was tagmented with the Nextera XT kit (Illumina) and sequenced as 75 bp paired-end reads on a NextSeq instrument using v2 reagents (Illumina). 14–22 million reads per sample were filtered for signal to noise (chastity filtered), assessed for overall quality with FastQC (http://www.bioinformatics.babraham.ac.uk/projects/fastqc/), and then mapped with STAR (Dobin et al., 2013) against the mouse genome build mm10.
Project description:Glioblastomas are aggressive primary brain cancers that invariably recur as therapy-resistant tumors. Myeloid cells control glioblastoma malignancy, but their dynamics during disease progression remains poorly understood. By relying on single-cell RNA and protein profiling, we mapped the glioblastoma immune landscape in newly diagnosed and recurrent patients and in mouse tumors. This revealed a large and diverse myeloid compartment, with dendritic cell and macrophage populations that were conserved across species and were dynamic across disease stages. Tumor-associated macrophages (TAMs) consisted of microglia- or monocyte-derived populations, with both exhibiting additional heterogeneity, including subsets with conserved lipid and hypoxic signatures. Microglia- and monocyte-derived TAMs (Mo-TAMs) were self-renewing populations that competed for space and could be depleted via CSF1R blockade. Microglia-derived TAMs were predominant in newly diagnosed tumors but were outnumbered by Mo-TAMs upon recurrence, especially in hypoxic tumor environments. Our results unravel the glioblastoma myeloid landscape and provide a framework for future therapeutic interventions.
Project description:In Glioblastoma (GBM), tumour-associated microglia/macrophages (TAMs) represent the most abundant cells of the stromal compartment contributing to tumour immune escape mechanisms. Thus, strategies targeting TAMs are emerging as promising objectives for immunotherapy. However, TAMs heterogeneity is only starting to emerge and little is known about their contribution to GBM progression. Here, we comprehensively study the molecular changes of TAMs in the GL261 GBM mouse model by single-cell RNA-sequencing across GBM progression and in the absence of Acod1/Irg1, a key gene involved in macrophage metabolic reprogramming. We identify distinct TAM profiles, mainly based on their ontogeny, which recapitulate microglia- versus macrophage-like features showing key transcriptional differences and rapidly adapting along GBM stages. Notably, we uncover a decreased antigen-presenting cell signature in TAMs along tumour progression that is less prominent in Acod1/Irg1-deficient mice. Overall, our results provide insights into TAMs heterogeneity and highlight a potential role for Acod1/Irg1 in TAMs polarization along GBM progression.
Project description:Glioblastoma 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. RNA was isolated from sorted tumor associated macrophages (TAMs) from murine gliomas following either 7 days of vehicle or BLZ945 treatment. Samples were collected from 16 total tumor burdened mice, with 8 replicates for each treatment group. BLZ945: a Colony-Stimulating Factor 1 Receptor (CSF-1R) inhibitor
Project description:Macrophages have been implicated in breast cancer progression and metastasis, but relatively little is known about the genes and pathways that are involved. Using a conditional allele of Ets2 in the mouse, we have identified Ets2 as a critical gene in tumor associated macrophages (TAMs) that specifically promotes mammary tumor metastasis. Loss of Ets2 in TAMs decreased the frequency and size of lung metastases without impacting primary tumor burden. Expression profiling of isolated tumor macrophages established that Ets2 deficiency resulted in the de-repression of a defined set of anti-angiogenic genes. Activation of this transcriptional program correlated with decreased angiogenesis in metastatic tumors and decreased metastatic growth. Comparison of this Ets2-specific TAM expression profile with human breast cancer profiles revealed a macrophage gene expression signature that could predict overall survival of estrogen receptor negative patients. In summary, we have identified a critical factor, Ets2, in TAMs that represses a transcriptional program to promote the growth of mammary tumor metastases in the lung. Breast TAMs were isolated from early-stage PyMT-induced mammary tumors expressing Ets2 and also from the tumors with Ets2-deficient TAMs. Since macrophages have also been implicated in normal mammary gland remodeling, normal remeodeling macrophages were also purified from females expressing Ets2 and the ones where Ets2 is deleted in the macrophages. One RNA sample was extracted from each genetic group for gene-expression profiling.
Project description:After central nervous system injury, a rapid neuroinflammatory response is induced. This response can be both beneficial and detrimental to neuronal survival in the first few days and increase the risk for neurodegeneration if it persists. Semaphorin4B (Sema4B), a transmembrane protein primarily expressed by cortical astrocytes, has been shown to play a role in neuronal cell death following injury. Our study shows that neuroinflammation is attenuated in Sema4B knockout mice and microglia/macrophage activation is reduced after cortical stab wound injury. In vitro, recombinant Sema4B enhances the activation of microglia following injury, suggesting astrocytic Sema4B functions as a ligand. Moreover, injury-induced activation of microglia is attenuated in the presence of Sema4B knockout astrocytes compared to heterozygous astrocytes. In vitro, experiments indicate Plexin-B2 is the Sema4B receptor on microglia. Consistent with this, microglia-specific Plexin-B2 knockout mice, similar to Sema4B knockout mice, also show a reduction in microglial activation after cortical injury. Finally, in Sema4B/Plexin-B2 double heterozygous mice, microglial activation is also reduced after injury, thus supporting the idea that both Sema4B and Plexin-B2 are part of the same signaling pathway. Taken together, we propose a model in which following injury, astrocytic Sema4B enhances the pro-inflammatory response of microglia/macrophages via Plexin-B2, leading to increased neuroinflammation.
Project description:Spinal ependymomas are the most common spinal cord tumors in adults, but their intratumoral cellular heterogeneity has been less studied, and how spinal microglia are involved in tumor progression is still unknown. Here, our single-cell RNA-sequencing analyses of three spinal ependymoma subtypes dissect the microenvironmental landscape of spinal ependymomas and reveal tumor-associated macrophage (TAM) subsets with distinct functional phenotypes. CCL2+ TAMs are related to the immune response and exhibit a high capacity for apoptosis, while CD44+ TAMs are associated with tumor angiogenesis. By combining these results with those of single-cell ATAC-sequencing data analysis, we reveal that TEAD1 and EGR3 play roles in regulating the functional diversity of TAMs. We further identify diverse characteristics of both malignant cells and TAMs that might underlie the different malignant degrees of each subtype. Finally, assessment of cell-cell interactions reveal that stromal cells act as extracellular factors that mediate TAM diversity. Overall, our results reveal dual functions of TAMs in tumor progression, providing valuable insights for TAM-targeting immunotherapy.
Project description:Macrophages are often prominently present in the tumor microenvironment, where distinct macrophage populations can differentially affect tumor progression. Although metabolism influences macrophage function, studies on the metabolic characteristics of ex vivo tumor-associated macrophage (TAM) subsets are rather limited. Using transcriptomic and metabolomic analyses, we now reveal that pro-inflammatory MHC-IIhi TAMs display a hampered TCA cycle, while reparative MHC-IIlo TAMs show a higher oxidative and glycolytic metabolism. Although both TAM subsets rapidly exchange lactate in high lactate conditions, only MHC-IIlo TAMs use lactate as an additional carbon source. Accordingly, lactate supports the oxidative metabolism in MHC-IIlo TAMs, while it decreased the metabolic activity of MHC-IIhi TAMs. Lactate subtly affected the transcriptome of MHC-IIlo TAMs, increased L-arginine metabolism and enhanced T-cell suppressive capacity of these TAMs. Overall, our data uncover the metabolic intricacies of distinct TAM subsets and identify lactate as a carbon source, and metabolic and functional regulator of TAMs.
Project description:Active immunotherapy is a promising strategy for anti-angiogenic cancer therapy. Recently, we have reported that a vaccine using human umbilical vein endothelial cells (HUVECs) induced specific anti-endothelial immune responses in the most of immunized patients, and resulted in tumor regression in some patients with recurrent malignant brain tumors, whereas not in colorectal cancer patients. In this study, we hypothesized that non-hypoxic perivascular tumor associated macrophages (TAMs) in colorectal cancer, but not in glioblastoma, might negatively alter the therapeutic efficacy of anti-angiogenic active immunotherapy. To test this hypothesis, we examined global gene expression profiles of non-hypoxic macrophages stimulated in vitro by soluble factors released from tumor cells of human glioblastoma U-87MG (‘brain TAMs’) or colorectal adenocarcinoma HT-29 (‘colon TAMs’). Murine non-hypoxic TAMs were induced in vitro by incubation with soluble factors released from human cancer cell lines U-87MG ('brain TAMs') or HT-29 ('colon TAMs'), for RNA extraction and subsequent hybridization on Affymetrix microarrays. To evaluate homogeneous macrophage populations at different tumour developmental stages, RNA aliquots of control macrophages and TAMs obtained at five different time-points, i.e. 8h, 16h, 24h, 32h and 40h, were pooled and used for screening of differentially expressed genes. The experiments for TAMs as well as for control unstimulated macrophages were performed in triplicates.