A major rate-limiting step in developing more effective immunotherapies for GBM is our inadequate understanding of the cellular complexity and the molecular heterogeneity of immune infiltrates in ...gliomas. Here, we report an integrated analysis of 201,986 human glioma, immune, and other stromal cells at the single cell level. In doing so, we discover extensive spatial and molecular heterogeneity in immune infiltrates. We identify molecular signatures for nine distinct myeloid cell subtypes, of which five are independent prognostic indicators of glioma patient survival. Furthermore, we identify S100A4 as a regulator of immune suppressive T and myeloid cells in GBM and demonstrate that deleting S100a4 in non-cancer cells is sufficient to reprogram the immune landscape and significantly improve survival. This study provides insights into spatial, molecular, and functional heterogeneity of glioma and glioma-associated immune cells and demonstrates the utility of this dataset for discovering therapeutic targets for this poorly immunogenic cancer.
Tumour cell phagocytosis by antigen presenting cells (APCs) is critical to the generation of antitumour immunity. However, cancer cells can evade phagocytosis by upregulating anti-phagocytosis ...molecule CD47. Here, we show that CD47 blockade alone is inefficient in stimulating glioma cell phagocytosis. However, combining CD47 blockade with temozolomide results in a significant pro-phagocytosis effect due to the latter's ability to induce endoplasmic reticulum stress response. Increased tumour cell phagocytosis subsequently enhances antigen cross-presentation and activation of cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) in APCs, resulting in more efficient T cell priming. This bridging of innate and adaptive responses inhibits glioma growth, but also activates immune checkpoint. Sequential administration of an anti-PD1 antibody overcomes this potential adaptive resistance. Together, these findings reveal a dynamic relationship between innate and adaptive immune regulation in tumours and support further investigation of phagocytosis modulation as a strategy to enhance cancer immunotherapy responses.
In the last several years, our appreciation of intra-tumoral heterogeneity has greatly increased due to accumulating evidence for the co-existence of genetically and epigenetically divergent cancer ...cells residing in different microenvironments within a tumor. Herein, we review recent literature discussing intra-tumoral heterogeneity in the context of therapy resistance mechanisms at the genetic, epigenetic and microenvironmental levels. We illustrate the influence of tumor microenvironment on therapy resistance and epigenetic states of cancer cells by highlighting the role of cancer stem cells in therapy resistance. We also summarize different strategies that have been employed to address various resistance mechanisms at genetic, epigenetic, and microenvironmental levels in preclinical and clinical studies. We propose that future personalized cancer therapy design needs to incorporate dynamic and comprehensive analyses of tumor heterogeneity landscape and multi-dimensional mechanisms of therapy resistance.
Exosomes are attractive as nucleic-acid carriers because of their favourable pharmacokinetic and immunological properties and their ability to penetrate physiological barriers that are impermeable to ...synthetic drug-delivery vehicles. However, inserting exogenous nucleic acids, especially large messenger RNAs, into cell-secreted exosomes leads to low yields. Here we report a cellular-nanoporation method for the production of large quantities of exosomes containing therapeutic mRNAs and targeting peptides. We transfected various source cells with plasmid DNAs and stimulated the cells with a focal and transient electrical stimulus that promotes the release of exosomes carrying transcribed mRNAs and targeting peptides. Compared with bulk electroporation and other exosome-production strategies, cellular nanoporation produced up to 50-fold more exosomes and a more than 10
-fold increase in exosomal mRNA transcripts, even from cells with low basal levels of exosome secretion. In orthotopic phosphatase and tensin homologue (PTEN)-deficient glioma mouse models, mRNA-containing exosomes restored tumour-suppressor function, enhanced inhibition of tumour growth and increased survival. Cellular nanoporation may enable the use of exosomes as a universal nucleic-acid carrier for applications requiring transcriptional manipulation.
Tumour-targeted immunotherapy offers the unique advantage of specific tumouricidal effects with reduced immune-associated toxicity. However, existing platforms suffer from low potency, inability to ...generate long-term immune memory and decreased activities against tumour-cell subpopulations with low targeting receptor levels. Here we adopted a modular design approach that uses colloidal nanoparticles as substrates to create a multivalent bi-specific nanobioconjugate engager (mBiNE) to promote selective, immune-mediated eradication of cancer cells. By simultaneously targeting the human epidermal growth factor receptor 2 (HER2) expressed by cancer cells and pro-phagocytosis signalling mediated by calreticulin, the mBiNE stimulated HER2-targeted phagocytosis and produced durable antitumour immune responses against HER2-expressing tumours. Interestingly, although the initial immune activation mediated by the mBiNE was receptor dependent, the subsequent antitumour immunity also generated protective effects against tumour-cell populations that lacked the HER2 receptor. Thus, the mBiNE represents a new targeted, nanomaterial-immunotherapy platform to stimulate innate and adaptive immunity and promote a universal antitumour response.
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IJS, NUK, SBMB, UL, UM, UPUK
The Notch pathway plays a pivotal role in regulating cell fate decisions in many stem cell systems. However, the full repertoire of Notch target genes in vivo and the mechanisms through which this ...pathway activity is integrated with other signaling pathways are largely unknown. Here, we report a transgenic mouse in which the activation of the Notch pathway massively expands the neural stem cell (NSC) pool in a cell context‐dependent manner. Using this in vivo system, we identify direct targets of RBPJ/N1ICD in cortical NSCs at a genome‐wide level through combined ChIP‐Seq and transcriptome analyses. Through a highly conservative analysis of these datasets, we identified 98 genes that are directly regulated by N1ICD/RPBJ in vivo. These include many transcription factors that are known to be critical for NSC self‐renewal (Sox2, Pax6, Tlx, and Id4) and the transcriptional effectors of the Wnt, SHH, and Hippo pathways, TCF4, Gli2, Gli3, Yap1, and Tead2. Since little is known about the function of the Hippo‐Yap pathway in NSCs, we analyzed Yap1 expression and function in NSCs. We show that Yap1 expression is restricted to the stem cell compartment in the developing forebrain and that its expression is sufficient to rescue Notch pathway inhibition in NSC self‐renewal assays. Together, results of this study reveal a previously underappreciated complexity and breadth of Notch1 targets in vivo and show direct interaction between Notch and Hippo‐Yap pathways in NSCs. STEM CELLS 2012; 30:741–752
Super-enhancers are large clusters of enhancers that activate gene expression. Broad trimethyl histone H3 lysine 4 (H3K4me3) often defines active tumor suppressor genes. However, how these epigenomic ...signatures are regulated for tumor suppression is little understood. Here we show that brain-specific knockout of the H3K4 methyltransferase MLL4 (a COMPASS-like enzyme, also known as KMT2D) in mice spontaneously induces medulloblastoma. Mll4 loss upregulates oncogenic Ras and Notch pathways while downregulating neuronal gene expression programs. MLL4 enhances DNMT3A-catalyzed DNA methylation and SIRT1/BCL6-mediated H4K16 deacetylation, which antagonize expression of Ras activators and Notch pathway components, respectively. Notably, Mll4 loss downregulates tumor suppressor genes (e.g., Dnmt3a and Bcl6) by diminishing broad H3K4me3 and super-enhancers and also causes widespread impairment of these epigenomic signatures during medulloblastoma genesis. These findings suggest an anti-tumor role for super-enhancers and provide a unique tumor-suppressive mechanism in which MLL4 is necessary to maintain broad H3K4me3 and super-enhancers at tumor suppressor genes.
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•Brain-specific Mll4 loss in mice results in spontaneous medulloblastoma•MLL4 upregulates DNMT3A-catalyzed DNA methylation to repress Ras activators•MLL4 enhances SIRT1/BCL6-mediated H4K16 deacetylation to downregulate Notch pathways•MLL4 establishes broad H3K4me3 and super-enhancers to activate tumor suppressor genes
Dhar et al. show that MLL4 suppresses medulloblastoma by establishing super-enhancers and broad H3K4me3 to activate multiple mechanisms that lead to activation of tumor suppressor genes and repression of oncogenes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Glioma stem cells (GSC) and epithelial-mesenchymal transition (EMT) are strongly associated with therapy resistance and tumor recurrence, but the underlying mechanisms are incompletely understood. ...Here, we show that S100A4 is a novel biomarker of GSCs. S100A4
cells in gliomas are enriched with cancer cells that have tumor-initiating and sphere-forming abilities, with the majority located in perivascular niches where GSCs are found. Selective ablation of S100A4-expressing cells was sufficient to block tumor growth
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We also identified S100A4 as a critical regulator of GSC self-renewal in mouse and patient-derived glioma tumorspheres. In contrast with previous reports of S100A4 as a reporter of EMT, we discovered that S100A4 is an upstream regulator of the master EMT regulators
and
along with other mesenchymal transition regulators in glioblastoma. Overall, our results establish S100A4 as a central node in a molecular network that controls stemness and EMT in glioblastoma, suggesting S100A4 as a candidate therapeutic target.
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The application of tumor immunotherapy to glioblastoma (GBM) is limited by an unprecedented degree of immune suppression due to factors that include high numbers of immune suppressive myeloid cells, ...the blood brain barrier, and T cell sequestration to the bone marrow. We previously identified an increase in immune suppressive myeloid-derived suppressor cells (MDSCs) in GBM patients, which correlated with poor prognosis and was dependent on macrophage migration inhibitory factor (MIF). Here we examine the MIF signaling axis in detail in murine MDSC models, GBM-educated MDSCs and human GBM. We found that the monocytic subset of MDSCs (M-MDSCs) expressed high levels of the MIF cognate receptor CD74 and was localized in the tumor microenvironment. In contrast, granulocytic MDSCs (G-MDSCs) expressed high levels of the MIF non-cognate receptor CXCR2 and showed minimal accumulation in the tumor microenvironment. Furthermore, targeting M-MDSCs with Ibudilast, a brain penetrant MIF-CD74 interaction inhibitor, reduced MDSC function and enhanced CD8 T cell activity in the tumor microenvironment. These findings demonstrate the MDSC subsets differentially express MIF receptors and may be leveraged for specific MDSC targeting.
CAG repeat expansion is the genetic cause of nine incurable polyglutamine (polyQ) diseases with neurodegenerative features. Silencing repeat RNA holds great therapeutic value. Here, we developed a ...repeat-based RNA-cleaving DNAzyme that catalyzes the destruction of expanded CAG repeat RNA of six polyQ diseases with high potency. DNAzyme preferentially cleaved the expanded allele in spinocerebellar ataxia type 1 (SCA1) cells. While cleavage was non-allele-specific for spinocerebellar ataxia type 3 (SCA3) cells, treatment of DNAzyme leads to improved cell viability without affecting mitochondrial metabolism or p62-dependent aggresome formation. DNAzyme appears to be stable in mouse brain for at least 1 month, and an intermediate dosage of DNAzyme in a SCA3 mouse model leads to a significant reduction of high molecular weight ATXN3 proteins. Our data suggest that DNAzyme is an effective RNA silencing molecule for potential treatment of multiple polyQ diseases.
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