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: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:Tumor-associated macrophages/microglia (TAMs) are prominent microenvironment components in human glioblastoma (GBM) that are potential targets for anti-tumor therapy. However, TAM depletion by CSF1R inhibition showed mixed results in clinical trials. We hypothesized that GBM subtype-specific tumor microenvironment convey distinct sensitivities to TAM targeting.We generated syngeneic PDGFB-driven and RAS-driven GBM models that resemble proneural-like and mesenchymal-like gliomas, and determined the effect of TAM targeting by CSF1R inhibitor PLX3397 on glioma growth. We also investigated the co-targeting of TAMs and angiogenesis on PLX3397-resistant RAS-driven GBM. Using single-cell transcriptomic profiling, we further explored differences in tumor microenvironment cellular compositions and functions in PDGFB- and RAS-driven gliomas. We found that growth of PDGFB-driven tumors was markedly inhibited by PLX3397. In contrast, depletion of TAMs at the early phase accelerated RAS-driven tumor growth and had no effects on other proneural and mesenchymal GBM models. In addition, PLX3397-resistant RAS-driven tumors did not respond to PI3K signaling inhibition. Single-cell transcriptomic profiling revealed that PDGFB-driven gliomas induced expansion and activation of pro-tumor microglia, whereas TAMs in mesenchymal RAS-driven GBM were enriched in pro-inflammatory and angiogenic signaling. Co-targeting of TAMs and angiogenesis decreased cell proliferation and changed the morphology of RAS-driven gliomas.Our work identify functionally distinct TAM subpopulations in the growth of different glioma subtypes. Notably, we uncover a potential responsiveness of resistant mesenchymal-like gliomas to combined anti-angiogenic therapy and CSF1R inhibition. These data highlight the importance of characterization of the microenvironment landscape in order to optimally stratify patients for TAM-targeted therapy.
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:We performed single-cell RNA sequencing of multiple IGF-1R loss-of function mouse mammary tumor models to uncover how IGF-1R signaling regulates intrinsic epithelial cell signaling to suppress metastasis. We identify key pathways necessary for promoting metastasis, determined IGF-1R is required to maintain a metastatic suppressive tumor microenvironment and demonstrate that attenuated epithelial IGF-1R signaling in the MMTV-Wnt1 mouse tumor model is sufficient for metastatic invasion. We further show that adherence between luminal and basal tumor cells is necessary for tumor growth at the secondary site and that reduced IGF-1R signaling in tumor epithelial cells inhibits secondary tumor epithelial cell growth due to dysregulated E-cadherin and P-cadherin and loss of cell-cell adhesion.
Project description:The insulin-like growth factor 1 receptor (IGF-1R) plays crucial roles in developmental and cancer biology. Most of its biological effects have been ascribed to its tyrosine kinase activity. We report that IGF-1 promotes the modification of IGF-1R by small ubiquitin-like modifier protein-1 (SUMO-1) and its translocation to the nucleus. Nuclear IGF-1R associated with enhancer-like elements and increased transcription in reporter assays. We used ChIP-seq to examine the interaction of IGF-1R with DNA on a genome-wide scale. Analysis of the data set resulted in 568 candidate peaks, that is, statistically significant IGF-1R-enriched regions. The IGF-1R-enriched regions were divided into five classes on the basis of their location relative to known genes. Most of the IGF-1R-interacting sites (80%) were located distal from any annotated gene (intergenic), 6.3% were located in introns, 6.3% in exons, 3.4% were <20 kb upstream of an annotated transcript start site (5'UTR + 20 kb upstream), and 3.6% were <20 kb downstream of an annotated transcript end site (3'UTR + 20 kb downstream).
Project description:Ewing Sarcoma is caused by a pathognomonic genomic translocation that places an N-terminal EWSR1 gene in approximation with one of several ETS genes (typically FLI1). This aberration, in turn, alters the transcriptional regulation of more than five hundred genes and perturbs a number of critical pathways that promote oncogenesis, cell growth, invasion, and metastasis. Among them, translocation-mediated up-regulation of the insulin-like growth factor receptor 1 (IGF-1R) and mammalian target of rapamycin (mTOR) are of particular importance since they work in concert to facilitate IGF-1R expression and ligand-induced activation, respectively, of proven importance in ES transformation. When used as a single agent in Ewing sarcoma therapy, IGF-1R or mTOR inhibition leads to rapid counter-regulatory effects that blunt the intended therapeutic purpose. Therefore, identify new mechanisms of resistance that are used by Ewing sarcoma to evade cell death to single-agent IGF-1R inhibition might suggest a number of therapeutic combinations that could improve its clinical activity. TC32 and TC71 ES clones with acquired resistance to OSI-906 or NVP-ADW-742 were generated by maintaining the corresponding parental cell lines with increasing concentrations of the agents (up to 2.3 μM for OSI-906, 1.5 μM for NVP-ADW-742) for 7 months. All parental and acquired drug resistant cell lines were tested twice per year for mycoplasma contamination using the MycoAlert Detection Kit (Lonza Group Ltd.) according to the manufacturerâs protocol and validated using short-tandem repeat fingerprinting with an AmpFLSTR Identifier kit as previously described. Herein, we determine subtle differences in acquired mechanism of resistance by two promising small molecule inhibitors of IGF-1R/IR-α. OSI-906, which inhibits IGF-1R and IR, and NVP-ADW-742, which inhibits only IGF-1R, were evaluated using in vitro assays to decipher the mechanism(s) by which IGF-1R inhibition induces drug resistance in Ewing sarcoma cells. The preparation of extracted proteins from sensitive and acquired resistant Ewing sarcoma cells to OSI-906 and NVP-ADW-742 for reverse-phase protein lysate array (RPPA) analysis were prepared using the same array. Lysates were processed, spotted onto nitrocellulose-coated FAST slides, probed with 115 validated primary antibodies, and detected using a DakoCytomation-catalyzed system with secondary antibodies. MicroVigene software program (VigeneTech) was used for automated spot identification, background correction, and individual spot-intensity determination. Expression data was normalized for possible unequal protein loading, taking into account the signal intensity for each sample for all antibodies tested. Log2 values were media-centered by protein to account for variability in signal intensity by time and were calculated using the formula log2 signal â log2 median. Principal component analysis was used to check for a batch effect and feature-by-feature two-sample t-tests were used to assess differences between sensitive and resistant cell lines to drug treatments. We also used feature-by-feature one-way analysis of variance (ANOVA) followed by the Tukey test to perform pair comparisons for all groups. Beta-uniform mixture models were used to fit the resulting p value distributions to adjust for multiple comparisons. The cutoff p values and number of significant proteins were computed for several different false discovery rates (FDRs). Biostatistical analyses comparing two groups were performed using an unpaired t-test with Gaussian distribution followed by the Welch correction. To distinguish between treatment groups, we used one-way ANOVA with the Geisser-Greenhouse correction. Differences with p values <0.05 were considered significant. Within clustered image maps (CIM), unsupervised double hierarchical clustering used the Pearson correlation distance and Wardâs linkage method as the clustering algorithm to link entities (proteins) and samples.
Project description:The insulin-like growth factor 1 receptor (IGF-1R) plays crucial roles in developmental and cancer biology. Most of its biological effects have been ascribed to its tyrosine kinase activity. We report that IGF-1 promotes the modification of IGF-1R by small ubiquitin-like modifier protein-1 (SUMO-1) and its translocation to the nucleus. Nuclear IGF-1R associated with enhancer-like elements and increased transcription in reporter assays. We used ChIP-seq to examine the interaction of IGF-1R with DNA on a genome-wide scale. Analysis of the data set resulted in 568 candidate peaks, that is, statistically significant IGF-1R-enriched regions. The IGF-1R-enriched regions were divided into five classes on the basis of their location relative to known genes. Most of the IGF-1R-interacting sites (80%) were located distal from any annotated gene (intergenic), 6.3% were located in introns, 6.3% in exons, 3.4% were <20 kb upstream of an annotated transcript start site (5'UTR + 20 kb upstream), and 3.6% were <20 kb downstream of an annotated transcript end site (3'UTR + 20 kb downstream). Analysis of the genomic interaction of IGF1R in DFB cells
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:Analysis of newborn mouse epidermis lacking the expression of Insulin receptor (IR) and Insulin like growth factor 1 receptor (IGF-1R). Results show that IR/IGF-1R signalling control epidermal morphogenesis.