Project description:Macrophages accumulate with glioblastoma multiforme (GBM) progression, and can be acutely targeted via inhibition of colony stimulating factor-1 receptor (CSF-1R) to regress high-grade tumors in animal models. However, whether and how resistance emerges in response to sustained CSF-1R blockade is unknown. Here, we investigate whether long-term CSF-1R inhibition can stably regress GBM in preclinical trials. We show that while overall survival is significantly prolonged, tumors recur eventually in >50% of mice. Upon isolation and transplantation of recurrent tumor cells into naïve animals, gliomas re-establish sensitivity to CSF-1R inhibition, indicating that resistance is microenvironment-driven. PI3K pathway activity was elevated in recurrent GBM, driven by macrophage-derived IGF-1 and tumor cell IGF-1R. Consequently, combining IGF-1R or PI3K blockade with continuous CSF-1R inhibition in recurrent tumors significantly prolonged overall survival. By contrast, monotherapy with IGF-1R or PI3K inhibitors in rebound or treatment-naïve tumors was less effective, indicating the necessity of combination therapy to expose PI3K signaling-dependency in recurrent disease. Our findings thus reveal a potential therapeutic approach for treating resistance to CSF-1R inhibitors in the clinical setting.
Project description:IGF1 and IGF1 receptors (IGF1R) are present in the adult heart and have been shown to be essential for myocardial performance. Insulin-like growth factor 1 (IGF1) is produced in numerous tissues particularly by the liver in response to growth hormone stimulation and is an important factor in the regulation of post-natal growth and development. We have generated and characterized transgenic mice over-expressing the IGF1R. We crossed IGF1R transgenic mice with dominant negative (dn)PI3K (p110) and with constitutively active (ca)PI3K(p110) transgenic mice. Expression profiling was performed on the ventricles of IGF1R, IGF1R-caPI3K, IGF1R-dnPI3K, caPI3K, dnPI3K transgenic female mice at 3 months of age. Non-transgenic littermates were used as controls.
Project description:Glioblastoma multiforme (GBM) is the most aggressive form of glioma, and is notorious for its terminal prognosis and lack of responsiveness to current treatment approaches. The brain tumor microenvironment (TME) represents a largely untapped reservoir of therapeutic target options in GBM. Here we have focused on the interplay between glioma cells and tumor-associated macrophages/ microglia (TAMs). TAMs accumulate in the gliomas with disease progression, and depend on colony stimulating factor 1 receptor (CSF-1R) signaling for survival. In a recent study from our laboratory, mice bearing high-grade gliomas were treated with a CSF-1R inhibitor, BLZ945 (Novartis), and tumors regressed significantly after just 7 days of treatment (PMID: 24056773). Here we investigate whether long-term treatment of high-grade gliomas with BLZ945 would result in stable management of disease in a mouse model of proneural GBM. We show that ~44% of mice survived to the trial end point (EP) with minimal disease by MRI and histology, whereas ~56% of mice showed tumor recurrence (Reb). Serial transplantation of rebound tumor cells into naïve animals re-established BLZ945 responsiveness, suggesting a role for the microenvironment in supporting recurrent disease. Indeed, RNA-seq analysis on FACS purified tumor cells and TAMs from EP and Reb tumors showed elevated PI3K signaling in Reb tumors, driven by a heterotypic paracrine interaction between TAM-derived IGF-1 and tumor cell IGF-1R. We performed combination trials to block IGF-1R or downstream PI3K signaling in rebound tumors with BLZ945 treatment, and were able to significantly prolong overall survival. Given that CSF-1R inhibitors are currently in clinical trials for multiple cancer types including for GBM, understanding the molecular mechanisms that underlie non-responsive/ resistant tumors is timely and critical.
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:IGF1 and IGF1 receptors (IGF1R) are present in the adult heart and have been shown to be essential for myocardial performance. Insulin-like growth factor 1 (IGF1) is produced in numerous tissues particularly by the liver in response to growth hormone stimulation and is an important factor in the regulation of post-natal growth and development. We have generated and characterized transgenic mice over-expressing the IGF1R. We crossed IGF1R transgenic mice with dominant negative (dn)PI3K (p110) and with constitutively active (ca)PI3K(p110) transgenic mice. Expression profiling was performed on the ventricles of IGF1R, IGF1R-caPI3K, IGF1R-dnPI3K, caPI3K, dnPI3K transgenic female mice at 3 months of age. Non-transgenic littermates were used as controls. Keywords = http://cardiogenomics.med.harvard.edu/groups/proj1/pages/igfr1_home.html Keywords: other
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.
Project description:Insulin-like growth factor (IGF1R) signalling has been implicated to play an important role in regulation of cardiac growth, hypertrophy and contractile function, and has been linked to the development of age related congestive heart failure. Here we address the question to what extent cardiomyocyte specific IGF1 signalling is essential for maintenance of the structural and functional integrity of the adult murine heart. To investigate the effects of IGF1 signalling in the adult heart without confounding effects due to IGF1 over-expression or adaptation during embryonic and early post-natal development, we inactivated the IGF1R by a 4-hydroxy tamoxifen inducible Cre recombinase in adult cardiac myocytes. Efficient inactivation of the IGF1R (iCMIGF1RKO) as assessed by Western analysis and real-time PCR went along with reduced IGF1-dependent AKT and GSK3β-phosphorylation. Functional analysis by conductance manometry and magnetic resonance imaging (MRI) revealed no functional alterations in young adult iCMIGF1RKO mice (age 3 month). However, when induced in aged mice (11 month) diastolic cardiac function was depressed. To address the question if insulin signalling might compensate for the defective IGF1R signalling we inactivated β-cells by streptozotocin. However, the diabetes associated functional depression was similar in controls and iCMIGF1RKO mice. Similarly, analysis of the cardiac gene expression profile on 44K microarrays did not reveal activation of overt adaptive processes. Endogenous IGF1 receptor signalling is required for conservation of cardiac function of the aging heart, but not for the integrity of cardiac structure and function of young hearts. Four samples of each group: the control group, positive for Cre recombinase, but negative for the floxed IGF-1R and the experimental group with double transgenic mice (merCremer/+ IGFloxP/IGFloxP).
Project description:The important role of IGF-1R in cancers has been well established. Classical model involves IGF-1/2 binding to IGF-1R, following activation of the PI3K/Akt pathway, thereby promoting cell proliferation, apoptosis inhibition and treatment resistance. While IGF-1R has become a promising target for cancer therapy, clinical disclosures subsequently have been less encouraging. The question is whether targeting IGF/IGF-1R still holds therapeutic potential. Here we show a novel mechanism that knockdown IGF-1R surprisingly triggers cytoplasmic viral RNA sensors MDA5 and RIG-1, leading to mitochondrial apoptosis in cancer. We analyzed MDA5 and RIG-1 in the intestinal epithelium of IGF-1R knockdown mice. Igf1r+/- mice demonstrated higher MDA5 and RIG-1 than WT mice. IGF-1R knockdown-triggered MDA5 and RIG-1 was further analyzed in human cancer and normal cells. Increased MDA5 and RIG-1 were clearly seen in the cytoplasm identified by immunofluoresce in the cells silenced IGF-1R. Block off IGF-1R downstream PI3K/Akt did not impact on MDA5 and RIG-1 expression. IGF-1R knockdown-triggered MDA5 and RIG-1 and their signaling pathways were similar to those of viral RNA mimetic poly(I:C) had. IGF-1R knockdown-triggered MDA5 and RIG-1 led to cancer apoptosis through activation of the mitochondrial pathway. In vivo assay, Igf1r+/- mice strongly resisted AOM-induced colonic tumorigenesis through triggering MDA¬5- and RIG-1-mediated apoptosis. Notably, RIG-I and MDA5-mediated proapoptotic signaling pathway is preferential active in cancer cells. These data suggest that targeting IGF-1R-triggered MDA5 and RIG-1 might have therapeutic potential for cancer treatment.
Project description:Treatment of glioblastoma with anti-CSF-1R immunotherapy, radiotherapy, or surgical tumor resection were found to all induce a fibrotic response to treatment, which was highly associated with tumor recurrence. To investigate the drivers of fibrotic treatment response we performed multi-omic analysis of the glioblastoma microenvironment following treatment with anti-CSF-1R immunotherapy. Studies consisted of mass spectrometry proteomic analysis, single cell transcriptomics, and high-dimensional spatial analysis. These data identified a protective spatial niche that supported tumor cell survival following treatment, ultimately leading to tumor recurrence. Therapeutic inhibition of fibrotic treatment response blocked the formation of this niche, and significantly improved survival in anti-CSF-1R preclinical trials
Project description:Parietal epithelial cells (PECs) are part of renal progenitor cells with similarities to bone marrow stem cell niche. In focal segmental glomerulosclerosis (FSGS) PECs become activated and contribute to extracellular matrix deposition. Colony stimulating factor-1 (CSF-1), a hematopoietic growth factor, acts via its specific receptor, CSF-1R, and has been implicated in several glomerular diseases, although its role on PEC activation is unknown. We found that CSF-1R was upregulated in PECs and podocytes from human biopsies with FSGS. Through in vitro studies, we demonstrated that PECs constitutively express CSF-1R. Incubation with CSF-1 induced CSF-1R upregulation and significant transcriptional regulation of genes involved in pathways associated with PEC activation. Specifically, CSF-1/CSF-1R activated the ERK1/2 pathway and upregulated CD44 in PECs, while both ERK and CSF-1R inhibitors reduced CD44 expression. Our functional studies showed that CSF-1 induced PEC proliferation and migration, while reducing the differentiation of PECs into podocytes. These results were validated in the Adriamycin-induced FSGS experimental model. Importantly, treatment with either the CSF-1R-specific inhibitor GW2580 or Ki20227 provided a robust therapeutic effect. In conclusion, we provide the first evidence of the role of the CSF-1/CSF-1R pathway in PEC activation in FSGS, paving the way for future clinical studies investigating the therapeutic effect of CSF-1R inhibitors on FSGS in humans.