Cancer can involve non-resolving, persistent inflammation where varying numbers of tumor-associated macrophages (TAMs) infiltrate and adopt different activation states between anti-tumor M1 and ...pro-tumor M2 phenotypes. Here, we resolve a cascade causing differential macrophage phenotypes in the tumor microenvironment. Reduction in TNF mRNA production or loss of type I TNF receptor signaling resulted in a striking pattern of enhanced M2 mRNA expression. M2 gene expression was driven in part by IL-13 from eosinophils co-recruited with inflammatory monocytes, a pathway that was suppressed by TNF. Our data define regulatory nodes within the tumor microenvironment that balance M1 and M2 populations. Our results show macrophage polarization in cancer is dynamic and dependent on the balance between TNF and IL-13, thus providing a strategy for manipulating TAMs.
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•Tumor-associated macrophages (TAMs) are heterogeneous populations•Loss of type I TNF receptor signaling causes a rise in M2 gene expression in TAMs•TNF mediates a global anti-M2 pathway•TNF suppresses IL-13 production from activated eosinophils
Macrophage “polarization” in cancer involves heterogeneity between the M1 and M2 phenotypes. Most research and clinical data link M2 macrophages to pro-tumor activities. Kratochvill et al. show that TNF is essential for suppressing the number of M2 tumor macrophages. TNF also blocks IL-13 production, a pro-M2 cytokine, from activated eosinophils.
Medulloblastomas that display a large cell/anaplastic morphology and overexpress the cellular c-MYC gene are highly aggressive and carry a very poor prognosis. This so-called MYC-subgroup differs in ...its histopathology, gene expression profile, and clinical behavior from other forms of medulloblastoma. We generated a mouse model of MYC-subgroup medulloblastoma by transducing Trp53-null cerebellar progenitor cells with Myc. The cardinal features of these mouse medulloblastomas closely mimic those of human MYC-subgroup tumors and significantly differ from mouse models of the Sonic-Hedgehog- and WNT-disease subgroups. This mouse model should significantly accelerate understanding and treatment of the most aggressive form of medulloblastoma and infers distinct roles for MYC and MYCN in tumorigenesis.
► Myc overexpression and Trp53 loss induce large cell anaplastic medulloblastoma ► The transcriptomes of human and mouse MYC-subgroup medulloblastoma are similar ► MYC-subgroup medulloblastomas are resistant to blockade of Sonic Hedgehog signaling
Selective targeting of N‐Myc‐driven Sonic hedgehog (SHH) medulloblastoma has been a challenge for many years and, despite decades of research, few targeted therapy opportunities exist. Recently, ...Kuzuoglu‐Ozturk et al. characterized the translatome of N‐Myc‐driven medulloblastoma as a promising therapeutic target. The study showed that N‐Myc controls a subset of members of the protein folding machinery that could be inhibited pharmacologically and validated a subset of Hsp70 functions as required for medulloblastoma progression in vitro and in vivo.
A new study by Kuzuoglu‐Ozturk et al. identified a novel therapeutic vulnerability in N‐Myc‐driven Sonic hedgehog medulloblastoma. Selective translation of protein homeostasis pathways, including protein folding machinery components, drives tumour cell response to proteotoxic stress. Targeting the Hsp70 co‐chaperone leaves cells vulnerable to the proteotoxic stress induced by N‐Myc overexpression and inhibits N‐Myc‐driven medulloblastoma proliferation.
We devised a high-throughput, cell-based assay to identify compounds to treat Group3 medulloblastoma (G3 MB). Mouse G3 MBs neurospheres were screened against a library of approximately 7,000 ...compounds including US Food and Drug Administration-approved drugs. We found that pemetrexed and gemcitabine preferentially inhibited G3 MB proliferation in vitro compared to control neurospheres and substantially inhibited G3 MB proliferation in vivo. When combined, these two drugs significantly increased survival of mice bearing cortical implants of mouse and human G3 MBs that overexpress MYC compared to each agent alone, while having little effect on mouse MBs of the sonic hedgehog subgroup. Our findings strongly suggest that combination therapy with pemetrexed and gemcitabine is a promising treatment for G3 MBs.
•Group3 medulloblastoma neurospheres were screened with FDA-approved drugs•Pemetrexed and gemcitabine inhibited mouse and human G3 and mouse SHH MBs in vitro•Pemetrexed and gemcitabine increased survival of mice bearing mouse and human G3 MB•Pemetrexed and gemcitabine did not affect survival of mice bearing mouse SHH MB
Group3 medulloblastoma (G3 MB) exhibits a high incidence of metastasis and poor patient prognosis. Morfouace et al. report that combination therapy with pemetrexed and gemcitabine, two drugs already in clinical use, effectively inhibits the proliferation of G3 MB that overexpresses MYC.
Medulloblastoma, originating in the cerebellum, is the most common malignant brain tumor in children. Medulloblastoma consists of four major groups where constitutive activation of the Sonic Hedgehog ...(SHH) signaling pathway is a hallmark of one group. Mouse and human SHH medulloblastomas exhibit increased expression of microRNAs encoded by the miR-17~92 and miR-106b~25 clusters compared with granule progenitors and postmitotic granule neurons. Here, we assessed the therapeutic potential of 8-mer seed-targeting locked nucleic acid (LNA)-modified anti-miR oligonucleotides, termed tiny LNAs, that inhibit microRNA seed families expressed by miR-17~92 and miR-106b~25 in two mouse models of SHH medulloblastomas. We found that tumor cells (medulloblastoma cells) passively took up 8-mer LNA-anti-miRs and specifically inhibited targeted microRNA seed-sharing family members. Inhibition of miR-17 and miR-19a seed families by anti-miR-17 and anti-miR-19, respectively, resulted in diminished tumor cell proliferation in vitro. Treatment of mice with systemic delivery of anti-miR-17 and anti-miR-19 reduced tumor growth in flank and brain allografts in vivo and prolonged the survival of mice with intracranial transplants, suggesting that inhibition of the miR-17~92 cluster family by 8-mer LNA-anti-miRs might be considered for the treatment of SHH medulloblastomas.
Of nine ependymoma molecular groups detected by DNA methylation profiling, the posterior fossa type A (PFA) is most prevalent. We used DNA methylation profiling to look for further molecular ...heterogeneity among 675 PFA ependymomas. Two major subgroups, PFA-1 and PFA-2, and nine minor subtypes were discovered. Transcriptome profiling suggested a distinct histogenesis for PFA-1 and PFA-2, but their clinical parameters were similar. In contrast, PFA subtypes differed with respect to age at diagnosis, gender ratio, outcome, and frequencies of genetic alterations. One subtype, PFA-1c, was enriched for 1q gain and had a relatively poor outcome, while patients with PFA-2c ependymomas showed an overall survival at 5 years of > 90%. Unlike other ependymomas, PFA-2c tumors express high levels of OTX2, a potential biomarker for this ependymoma subtype with a good prognosis. We also discovered recurrent mutations among PFA ependymomas. H3 K27M mutations were present in 4.2%, occurring only in PFA-1 tumors, and missense mutations in an uncharacterized gene,
CXorf67
, were found in 9.4% of PFA ependymomas, but not in other groups. We detected high levels of wildtype or mutant
CXorf67
expression in all PFA subtypes except PFA-1f, which is enriched for H3 K27M mutations. PFA ependymomas are characterized by lack of H3 K27 trimethylation (H3 K27-me3), and we tested the hypothesis that CXorf67 binds to PRC2 and can modulate levels of H3 K27-me3. Immunoprecipitation/mass spectrometry detected EZH2, SUZ12, and EED, core components of the PRC2 complex, bound to CXorf67 in the Daoy cell line, which shows high levels of
CXorf67
and no expression of H3 K27-me3. Enforced reduction of CXorf67 in Daoy cells restored H3 K27-me3 levels, while enforced expression of CXorf67 in HEK293T and neural stem cells reduced H3 K27-me3 levels. Our data suggest that heterogeneity among PFA ependymomas could have clinicopathologic utility and that
CXorf67
may have a functional role in these tumors.
Medulloblastomas (MBs) are the most common brain tumors in children. Some are thought to originate from cerebellar granule neuron progenitors (GNPs) that fail to undergo normal cell cycle exit and ...differentiation. Because microRNAs regulate numerous aspects of cellular physiology and development, we reasoned that alterations in miRNA expression might contribute to MB. We tested this hypothesis using 2 spontaneous mouse MB models with specific initiating mutations, Ink4c-/-; Ptch1+/- and Ink4c-/-; p53-/-. We found that 26 miRNAs showed increased expression and 24 miRNAs showed decreased expression in proliferating mouse GNPs and MBs relative to mature mouse cerebellum, regardless of genotype. Among the 26 overexpressed miRNAs, 9 were encoded by the miR-17~92 cluster family, a group of microRNAs implicated as oncogenes in several tumor types. Analysis of human MBs demonstrated that 3 miR-17~92 cluster miRNAs (miR-92, miR-19a, and miR-20) were also overexpressed in human MBs with a constitutively activated Sonic Hedgehog (SHH) signaling pathway, but not in other forms of the disease. To test whether the miR-17~92 cluster could promote MB formation, we enforced expression of these miRNAs in GNPs isolated from cerebella of postnatal (P) day P6 Ink4c-/-; Ptch1+/- mice. These, but not similarly engineered cells from Ink4c-/-; p53-/- mice, formed MBs in orthotopic transplants with complete penetrance. Interestingly, orthotopic mouse tumors ectopically expressing miR-17~92 lost expression of the wild-type Ptch1 allele. Our findings suggest a functional collaboration between the miR-17~92 cluster and the SHH signaling pathway in the development of MBs in mouse and man.
Targeting cereblon (CRBN) is currently one of the most frequently reported proteolysis‐targeting chimera (PROTAC) approaches, owing to favorable drug‐like properties of CRBN ligands, immunomodulatory ...imide drugs (IMiDs). However, IMiDs are known to be inherently unstable, readily undergoing hydrolysis in body fluids. Here we show that IMiDs and IMiD‐based PROTACs rapidly hydrolyze in commonly utilized cell media, which significantly affects their cell efficacy. We designed novel CRBN binders, phenyl glutarimide (PG) analogues, and showed that they retained affinity for CRBN with high ligand efficiency (LE >0.48) and displayed improved chemical stability. Our efforts led to the discovery of PG PROTAC 4 c (SJ995973), a uniquely potent degrader of bromodomain and extra‐terminal (BET) proteins that inhibited the viability of human acute myeloid leukemia MV4‐11 cells at low picomolar concentrations (IC50=3 pM; BRD4 DC50=0.87 nM). These findings strongly support the utility of PG derivatives in the design of CRBN‐directed PROTACs.
IMiD‐based PROTACs rapidly hydrolyze in commonly utilized cell media, which significantly affects their cell efficacy. We designed novel BET PROTACs based on phenyl glutarimide (PG) and showed that they retained affinity for CRBN and displayed improved chemical stability. To demonstrate the utility of PG‐based PROTACs we developed SJ995973 (4 c), a uniquely potent degrader of BET proteins.
Mouse models of medulloblastoma have proven to be instrumental in understanding disease mechanisms, particularly the role of epigenetic and molecular drivers, and establishing appropriate preclinical ...pipelines. To date, our research community has developed murine models for all four groups of medulloblastoma, each of which will be critical for the identification and development of new therapeutic approaches. Approaches to modeling medulloblastoma range from genetic engineering with CRISPR/Cas9 or in utero electroporation, to orthotopic and patient‐derived orthotopic xenograft systems. Each approach or model presents unique advantages that have ultimately contributed to an appreciation of medulloblastoma heterogeneity and the clinical obstacles that exist for this patient population.
Coordinated regulation of the lysosomal and autophagic systems ensures basal catabolism and normal cell physiology, and failure of either system causes disease. Here we describe an epigenetic ...rheostat orchestrated by c-MYC and histone deacetylases that inhibits lysosomal and autophagic biogenesis by concomitantly repressing the expression of the transcription factors MiT/TFE and FOXH1, and that of lysosomal and autophagy genes. Inhibition of histone deacetylases abates c-MYC binding to the promoters of lysosomal and autophagy genes, granting promoter occupancy to the MiT/TFE members, TFEB and TFE3, and/or the autophagy regulator FOXH1. In pluripotent stem cells and cancer, suppression of lysosomal and autophagic function is directly downstream of c-MYC overexpression and may represent a hallmark of malignant transformation. We propose that, by determining the fate of these catabolic systems, this hierarchical switch regulates the adaptive response of cells to pathological and physiological cues that could be exploited therapeutically.
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