bims-malgli 2024-01-14 papers

bims-malgli

Biomed News

on Biology of malignant gliomas

Issue of 2024–01–14
twelve papers selected by
Oltea Sampetrean, Keio University

Tumor-specific migration routes of xenotransplanted human glioblastoma cells in mouse brain.
Proteomic, Metabolomic, and Fatty Acid Profiling of Small Extracellular Vesicles from Glioblastoma Stem-Like Cells and Their Role in Tumor Heterogeneity.
Integrated proteogenomic characterization of glioblastoma evolution.
The paracaspase MALT1 controls cholesterol homeostasis in glioblastoma stem-like cells through lysosome proteome shaping.
Involvement of the tumour necrosis factor receptor system in glioblastoma cell death induced by palbociclib-heptamethine cyanine dye conjugate.
Improved prognostic stratification of patients with isocitrate dehydrogenase-mutant astrocytoma.
Carcinoembryonic antigen-expressing oncolytic measles virus derivative in recurrent glioblastoma: a phase 1 trial.
Aberrant DNA repair reveals a vulnerability in histone H3.3-mutant brain tumors.
The immune system and metabolic products in epilepsy and glioma-associated epilepsy: emerging therapeutic directions.
Repeated peripheral infusions of anti-EGFRvIII CAR T cells in combination with pembrolizumab show no efficacy in glioblastoma: a phase 1 trial.
Structural connectome-based predictive modeling of cognitive deficits in treated glioma patients.
Antigen presentation deficiency, mesenchymal differentiation, and resistance to immunotherapy in the murine syngeneic CT2A tumor model.

Sci Rep. 2024 01 09. 14(1): 864

Tumor-specific migration routes of xenotransplanted human glioblastoma cells in mouse brain.

Rajesh Kumar Gupta, Mia Niklasson, Tobias Bergström, Anna Segerman, Christer Betsholtz, Bengt Westermark.

The migration of neural progenitor cells (NPCs) to their final destination during development follows well-defined pathways, such as along blood vessels. Cells originating from the highly malignant tumor glioblastoma (GBM) seem to exploit similar routes for infiltrating the brain parenchyma. In this report, we have examined the migration of GBM cells using three-dimensional high-resolution confocal microscopy in brain tumors derived from eight different human GBM cell lines xenografted into immunodeficient mice. The primary invasion routes identified were long-distance migration along white matter tracts and local migration along blood vessels. We found that GBM cells in the majority of tumors (6 out of 8) did not exhibit association with blood vessels. These tumors, derived from low lamin A/C expressing GBM cells, were comparatively highly diffusive and invasive. Conversely, in 2 out of 8 tumors, we noted perivascular invasion and displacement of astrocyte end-feet. These tumors exhibited less diffusive migration, grew as solid tumors, and were distinguished by elevated expression of lamin A/C. We conclude that the migration pattern of glioblastoma is distinctly tumor cell-specific. Furthermore, the ability to invade the confined spaces within white matter tracts may necessitate low expression of lamin A/C, contributing to increased nuclear plasticity. This study highlights the role of GBM heterogeneity in driving the aggressive growth of glioblastoma.

DOI: https://doi.org/10.1038/s41598-023-51063-7
ACS Nano. 2024 Jan 11.

Proteomic, Metabolomic, and Fatty Acid Profiling of Small Extracellular Vesicles from Glioblastoma Stem-Like Cells and Their Role in Tumor Heterogeneity.

Tolga Lokumcu, Murat Iskar, Martin Schneider, Dominic Helm, Glynis Klinke, Lisa Schlicker, Frederic Bethke, Gabriele Müller, Karsten Richter, Gernot Poschet, Emma Phillips, Violaine Goidts.

  Glioblastoma is a deadly brain tumor for which there is no cure. The presence of glioblastoma stem-like cells (GSCs) contributes to the heterogeneous nature of the disease and makes developing effective therapies challenging. Glioblastoma cells have been shown to influence their environment by releasing biological nanostructures known as extracellular vesicles (EVs). Here, we investigated the role of GSC-derived nanosized EVs (<200 nm) in glioblastoma heterogeneity, plasticity, and aggressiveness, with a particular focus on their protein, metabolite, and fatty acid content. We showed that conditioned medium and small extracellular vesicles (sEVs) derived from cells of one glioblastoma subtype induced transcriptomic and proteomic changes in cells of another subtype. We found that GSC-derived sEVs are enriched in proteins playing a role in the transmembrane transport of amino acids, carboxylic acids, and organic acids, growth factor binding, and metabolites associated with amino acid, carboxylic acid, and sugar metabolism. This suggests a dual role of GSC-derived sEVs in supplying neighboring GSCs with valuable metabolites and proteins responsible for their transport. Moreover, GSC-derived sEVs were enriched in saturated fatty acids, while their respective cells were high in unsaturated fatty acids, supporting that the loading of biological cargos into sEVs is a highly regulated process and that GSC-derived sEVs could be sources of saturated fatty acids for the maintenance of glioblastoma cell metabolism. Interestingly, sEVs isolated from GSCs of the proneural and mesenchymal subtypes are enriched in specific sets of proteins, metabolites, and fatty acids, suggesting a molecular collaboration between transcriptionally different glioblastoma cells. In summary, this study revealed the complexity of GSC-derived sEVs and unveiled their potential contribution to tumor heterogeneity and critical cellular processes commonly deregulated in glioblastoma.

Keywords:  exosomes; fatty acids; glioblastoma; glioblastoma stem-like cells; metabolomics; proteomics; small extracellular vesicles

DOI:  https://doi.org/10.1021/acsnano.3c11427
Cancer Cell. 2024 Jan 01. pii: S1535-6108(23)00443-9. [Epub ahead of print]

Integrated proteogenomic characterization of glioblastoma evolution.

Kyung-Hee Kim, Simona Migliozzi, Harim Koo, Jun-Hee Hong, Seung Min Park, Sooheon Kim, Hyung Joon Kwon, Seokjun Ha, Luciano Garofano, Young Taek Oh, Fulvio D'Angelo, Chan Il Kim, Seongsoo Kim, Ji Yoon Lee, Jiwon Kim, Jisoo Hong, Eun-Hae Jang, Bertrand Mathon, Anna-Luisa Di Stefano, Franck Bielle, Alice Laurenge, Alexey I Nesvizhskii, Eun-Mi Hur, Jinlong Yin, Bingyang Shi, Youngwook Kim, Kyung-Sub Moon, Jeong Taik Kwon, Shin Heon Lee, Seung Hoon Lee, Ho Shin Gwak, Anna Lasorella, Heon Yoo, Marc Sanson, Jason K Sa, Chul-Kee Park, Do-Hyun Nam, Antonio Iavarone, Jong Bae Park.

  The evolutionary trajectory of glioblastoma (GBM) is a multifaceted biological process that extends beyond genetic alterations alone. Here, we perform an integrative proteogenomic analysis of 123 longitudinal glioblastoma pairs and identify a highly proliferative cellular state at diagnosis and replacement by activation of neuronal transition and synaptogenic pathways in recurrent tumors. Proteomic and phosphoproteomic analyses reveal that the molecular transition to neuronal state at recurrence is marked by post-translational activation of the wingless-related integration site (WNT)/ planar cell polarity (PCP) signaling pathway and BRAF protein kinase. Consistently, multi-omic analysis of patient-derived xenograft (PDX) models mirror similar patterns of evolutionary trajectory. Inhibition of B-raf proto-oncogene (BRAF) kinase impairs both neuronal transition and migration capability of recurrent tumor cells, phenotypic hallmarks of post-therapy progression. Combinatorial treatment of temozolomide (TMZ) with BRAF inhibitor, vemurafenib, significantly extends the survival of PDX models. This study provides comprehensive insights into the biological mechanisms of glioblastoma evolution and treatment resistance, highlighting promising therapeutic strategies for clinical intervention.

Keywords:  BRAF; longitudinal glioblastoma; neuronal; proteogenomics; recurrence; synapse

DOI:  https://doi.org/10.1016/j.ccell.2023.12.015
Cell Rep. 2024 Jan 05. pii: S2211-1247(23)01642-X. [Epub ahead of print]43(1): 113631

The paracaspase MALT1 controls cholesterol homeostasis in glioblastoma stem-like cells through lysosome proteome shaping.

Clément Maghe, Kilian Trillet, Gwennan André-Grégoire, Mathilde Kerhervé, Laura Merlet, Kathryn A Jacobs, Kristine Schauer, Nicolas Bidère, Julie Gavard.

  Glioblastoma stem-like cells (GSCs) compose a tumor-initiating and -propagating population remarkably vulnerable to variation in the stability and integrity of the lysosomal compartment. Previous work has shown that the expression and activity of the paracaspase MALT1 control GSC viability via lysosome abundance. However, the underlying mechanisms remain elusive. By combining RNA sequencing (RNA-seq) with proteome-wide label-free quantification, we now report that MALT1 repression in patient-derived GSCs alters the homeostasis of cholesterol, which accumulates in late endosomes (LEs)-lysosomes. This failure in cholesterol supply culminates in cell death and autophagy defects, which can be partially reverted by providing exogenous membrane-permeable cholesterol to GSCs. From a molecular standpoint, a targeted lysosome proteome analysis unraveled that Niemann-Pick type C (NPC) lysosomal cholesterol transporters are diluted when MALT1 is impaired. Accordingly, we found that NPC1/2 inhibition and silencing partially mirror MALT1 loss-of-function phenotypes. This supports the notion that GSC fitness relies on lysosomal cholesterol homeostasis.

Keywords:  CP: Cancer; CP: Cell biology; Niemann-Pick disease; SREBP2; autophagy; cholesterol; glioblastoma; glioma; late endosome; lysosome; proteome; transporter

DOI:  https://doi.org/10.1016/j.celrep.2023.113631
Cell Commun Signal. 2024 Jan 11. 22(1): 30

Involvement of the tumour necrosis factor receptor system in glioblastoma cell death induced by palbociclib-heptamethine cyanine dye conjugate.

Elizabeth Cooper, Caitlin R M Oyagawa, Rebecca Johnson, Peter J Choi, Jena Macapagal Foliaki, Jason Correia, Patrick Schweder, Peter Heppner, Edward Mee, Clinton Turner, Richard Faull, William A Denny, Mike Dragunow, Jiney Jose, Thomas I-H Park.

Glioblastoma is the most common and aggressive primary brain tumour in adults. The development of anti-brain cancer agents are challenged by the blood-brain barrier and the resistance conferred by the local tumour microenvironment. Heptamethine cyanine dyes (HMCDs) are a class of near-infrared fluorescence compounds that have recently emerged as promising agents for drug delivery. We conjugated palbociclib, a cyclin-dependent kinase (CDK) 4/6 inhibitor, to an HMCD, MHI-148, and conducted drug activity analysis on primary patient-derived glioblastoma cell lines. In addition to the expected cytostatic activity, our in vitro studies revealed that palbociclib-MHI-148 conjugate resulted in an almost 100-fold increase in cytotoxicity compared to palbociclib alone. This shift of palbociclib from cytostatic to cytotoxic when conjugated to MHI-148 was due to increased DNA damage, as indicated by an increase in γH2AX foci, followed by an increased expression of key extrinsic apoptosis genes, including TP53, TNFR1, TRAIL, FADD and caspase 8. In addition, we observed a time-dependent increase in the cell surface expression of TNFR1, consistent with an observed increase in the secretion TNFα, followed by TNFR1 endocytosis at 48 h. The treatment of patient GBM cells with the palbociclib-MHI-148 conjugate prevented TNFα-induced NFκB translocation, suggesting conjugate-induced TNFR1 signalling favoured the TNFR1-mediated apoptotic response rather than the pro-inflammatory response pathway. Notably, pharmacological inhibition of endocytosis of TNFR1, and siRNA-knockdown of TNFR1 reversed the palbociclib-MHI-148-induced cell death. These results show a novel susceptibility of glioblastoma cells to TNFR1-dependent apoptosis, dependent on inhibition of canonical NFκB signalling using our previously reported palbociclib-HMCD conjugate. Video Abstract.

DOI: https://doi.org/10.1186/s12964-023-01277-z
Acta Neuropathol. 2024 Jan 06. 147(1): 11

Improved prognostic stratification of patients with isocitrate dehydrogenase-mutant astrocytoma.

Michael Weller, Jörg Felsberg, Bettina Hentschel, Dorothee Gramatzki, Nadezhda Kubon, Marietta Wolter, Matthias Reusche, Patrick Roth, Dietmar Krex, Ulrich Herrlinger, Manfred Westphal, Joerg C Tonn, Luca Regli, Claude-Alain Maurage, Andreas von Deimling, Torsten Pietsch, Emilie Le Rhun, Guido Reifenberger.

  Prognostic factors and standards of care for astrocytoma, isocitrate dehydrogenase (IDH)-mutant, CNS WHO grade 4, remain poorly defined. Here we sought to explore disease characteristics, prognostic markers, and outcome in patients with this newly defined tumor type. We determined molecular biomarkers and assembled clinical and outcome data in patients with IDH-mutant astrocytomas confirmed by central pathology review. Patients were identified in the German Glioma Network cohort study; additional cohorts of patients with CNS WHO grade 4 tumors were identified retrospectively at two sites. In total, 258 patients with IDH-mutant astrocytomas (114 CNS WHO grade 2, 73 CNS WHO grade 3, 71 CNS WHO grade 4) were studied. The median age at diagnosis was similar for all grades. Karnofsky performance status at diagnosis inversely correlated with CNS WHO grade (p < 0.001). Despite more intensive treatment upfront with higher grade, CNS WHO grade was strongly prognostic: median overall survival was not reached for grade 2 (median follow-up 10.4 years), 8.1 years (95% CI 5.4-10.8) for grade 3, and 4.7 years (95% CI 3.4-6.0) for grade 4. Among patients with CNS WHO grade 4 astrocytoma, median overall survival was 5.5 years (95% CI 4.3-6.7) without (n = 58) versus 1.8 years (95% CI 0-4.1) with (n = 12) homozygous CDKN2A deletion. Lower levels of global DNA methylation as detected by LINE-1 methylation analysis were strongly associated with CNS WHO grade 4 (p < 0.001) and poor outcome. MGMT promoter methylation status was not prognostic for overall survival. Histomolecular stratification based on CNS WHO grade, LINE-1 methylation level, and CDKN2A status revealed four subgroups of patients with significantly different outcomes. In conclusion, CNS WHO grade, global DNA methylation status, and CDKN2A homozygous deletion are prognostic in patients with IDH-mutant astrocytoma. Combination of these parameters allows for improved prediction of outcome. These data aid in designing upcoming trials using IDH inhibitors.

Keywords:  Brain; CDKN2A; CNS WHO grade; IDH; LINE-1; Molecular

DOI:  https://doi.org/10.1007/s00401-023-02662-1
Nat Commun. 2024 Jan 12. 15(1): 493

Carcinoembryonic antigen-expressing oncolytic measles virus derivative in recurrent glioblastoma: a phase 1 trial.

Evanthia Galanis, Katharine E Dooley, S Keith Anderson, Cheyne B Kurokawa, Xiomara W Carrero, Joon H Uhm, Mark J Federspiel, Alexey A Leontovich, Ileana Aderca, Kimberly B Viker, Julie E Hammack, Randolph S Marks, Steven I Robinson, Derek R Johnson, Timothy J Kaufmann, Jan C Buckner, Daniel H Lachance, Terry C Burns, Caterina Giannini, Aditya Raghunathan, Ianko D Iankov, Ian F Parney.

Measles virus (MV) vaccine strains have shown significant preclinical antitumor activity against glioblastoma (GBM), the most lethal glioma histology. In this first in human trial (NCT00390299), a carcinoembryonic antigen-expressing oncolytic measles virus derivative (MV-CEA), was administered in recurrent GBM patients either at the resection cavity (Group A), or, intratumorally on day 1, followed by a second dose administered in the resection cavity after tumor resection on day 5 (Group B). A total of 22 patients received study treatment, 9 in Group A and 13 in Group B. Primary endpoint was safety and toxicity: treatment was well tolerated with no dose-limiting toxicity being observed up to the maximum feasible dose (2×107 TCID50). Median OS, a secondary endpoint, was 11.6 mo and one year survival was 45.5% comparing favorably with contemporary controls. Other secondary endpoints included assessment of viremia, MV replication and shedding, humoral and cellular immune response to the injected virus. A 22 interferon stimulated gene (ISG) diagonal linear discriminate analysis (DLDA) classification algorithm in a post-hoc analysis was found to be inversely (R = -0.6, p = 0.04) correlated with viral replication and tumor microenvironment remodeling including proinflammatory changes and CD8 + T cell infiltration in post treatment samples. This data supports that oncolytic MV derivatives warrant further clinical investigation and that an ISG-based DLDA algorithm can provide the basis for treatment personalization.

DOI: https://doi.org/10.1038/s41467-023-43076-7
Nucleic Acids Res. 2024 Jan 12. pii: gkad1257. [Epub ahead of print]

Aberrant DNA repair reveals a vulnerability in histone H3.3-mutant brain tumors.

Giulia Giacomini, Sandra Piquet, Odile Chevallier, Juliette Dabin, Siau-Kun Bai, Byungjin Kim, Robert Siddaway, Brian Raught, Etienne Coyaud, Chun-Min Shan, Robert J D Reid, Takenori Toda, Rodney Rothstein, Viviana Barra, Therese Wilhelm, Sabah Hamadat, Chloé Bertin, Alexander Crane, Frank Dubois, Ignasi Forne, Axel Imhof, Pratiti Bandopadhayay, Rameen Beroukhim, Valeria Naim, Songtao Jia, Cynthia Hawkins, Beatrice Rondinelli, Sophie E Polo.

Pediatric high-grade gliomas (pHGG) are devastating and incurable brain tumors with recurrent mutations in histone H3.3. These mutations promote oncogenesis by dysregulating gene expression through alterations of histone modifications. We identify aberrant DNA repair as an independent mechanism, which fosters genome instability in H3.3 mutant pHGG, and opens new therapeutic options. The two most frequent H3.3 mutations in pHGG, K27M and G34R, drive aberrant repair of replication-associated damage by non-homologous end joining (NHEJ). Aberrant NHEJ is mediated by the DNA repair enzyme polynucleotide kinase 3'-phosphatase (PNKP), which shows increased association with mutant H3.3 at damaged replication forks. PNKP sustains the proliferation of cells bearing H3.3 mutations, thus conferring a molecular vulnerability, specific to mutant cells, with potential for therapeutic targeting.

DOI: https://doi.org/10.1093/nar/gkad1257
JCI Insight. 2024 Jan 09. pii: e174753. [Epub ahead of print]9(1):

The immune system and metabolic products in epilepsy and glioma-associated epilepsy: emerging therapeutic directions.

Shashwat Tripathi, Cody L Nathan, Matthew C Tate, Craig M Horbinski, Jessica W Templer, Joshua M Rosenow, Timothy L Sita, Charles D James, Benjamin Deneen, Stephen D Miller, Amy B Heimberger.

Epilepsy has a profound impact on quality of life. Despite the development of new antiseizure medications (ASMs), approximately one-third of affected patients have drug-refractory epilepsy and are nonresponsive to medical treatment. Nearly all currently approved ASMs target neuronal activity through ion channel modulation. Recent human and animal model studies have implicated new immunotherapeutic and metabolomic approaches that may benefit patients with epilepsy. In this Review, we detail the proinflammatory immune landscape of epilepsy and contrast this with the immunosuppressive microenvironment in patients with glioma-related epilepsy. In the tumor setting, excessive neuronal activity facilitates immunosuppression, thereby contributing to subsequent glioma progression. Metabolic modulation of the IDH1-mutant pathway provides a dual pathway for reversing immune suppression and dampening seizure activity. Elucidating the relationship between neurons and immunoreactivity is an area for the prioritization and development of the next era of ASMs.

DOI: https://doi.org/10.1172/jci.insight.174753
Nat Cancer. 2024 Jan 12.

Repeated peripheral infusions of anti-EGFRvIII CAR T cells in combination with pembrolizumab show no efficacy in glioblastoma: a phase 1 trial.

Stephen J Bagley, Zev A Binder, Lamia Lamrani, Eliana Marinari, Arati S Desai, MacLean P Nasrallah, Eileen Maloney, Steven Brem, Robert A Lustig, Goldie Kurtz, Michelle Alonso-Basanta, Pierre-Emmanuel Bonté, Christel Goudot, Wilfrid Richer, Eliane Piaggio, Shawn Kothari, Lea Guyonnet, Coralie L Guerin, Joshua J Waterfall, Suyash Mohan, Wei-Ting Hwang, Oliver Y Tang, Meghan Logun, Meghna Bhattacharyya, Kelly Markowitz, Devora Delman, Amy Marshall, E John Wherry, Sebastian Amigorena, Gregory L Beatty, Jennifer L Brogdon, Elizabeth Hexner, Denis Migliorini, Cecile Alanio, Donald M O'Rourke.

We previously showed that chimeric antigen receptor (CAR) T-cell therapy targeting epidermal growth factor receptor variant III (EGFRvIII) produces upregulation of programmed death-ligand 1 (PD-L1) in the tumor microenvironment (TME). Here we conducted a phase 1 trial (NCT03726515) of CAR T-EGFRvIII cells administered concomitantly with the anti-PD1 (aPD1) monoclonal antibody pembrolizumab in patients with newly diagnosed, EGFRvIII+ glioblastoma (GBM) (n = 7). The primary outcome was safety, and no dose-limiting toxicity was observed. Secondary outcomes included median progression-free survival (5.2 months; 90% confidence interval (CI), 2.9-6.0 months) and median overall survival (11.8 months; 90% CI, 9.2-14.2 months). In exploratory analyses, comparison of the TME in tumors harvested before versus after CAR + aPD1 administration demonstrated substantial evolution of the infiltrating myeloid and T cells, with more exhausted, regulatory, and interferon (IFN)-stimulated T cells at relapse. Our study suggests that the combination of CAR T cells and PD-1 inhibition in GBM is safe and biologically active but, given the lack of efficacy, also indicates a need to consider alternative strategies.

DOI: https://doi.org/10.1038/s43018-023-00709-6
Neurooncol Adv. 2024 Jan-Dec;6(1):6(1): vdad151

Structural connectome-based predictive modeling of cognitive deficits in treated glioma patients.

Michel Friedrich, Christian P Filss, Philipp Lohmann, Felix M Mottaghy, Gabriele Stoffels, Carolin Weiss Lucas, Maximilian I Ruge, N Jon Shah, Svenja Caspers, Karl-Josef Langen, Gereon R Fink, Norbert Galldiks, Martin Kocher.

   Background: In glioma patients, tumor growth and subsequent treatments are associated with various types of brain lesions. We hypothesized that cognitive functioning in these patients critically depends on the maintained structural connectivity of multiple brain networks.
Methods: The study included 121 glioma patients (median age, 52 years; median Eastern Cooperative Oncology Group performance score 1; CNS-WHO Grade 3 or 4) after multimodal therapy. Cognitive performance was assessed by 10 tests in 5 cognitive domains at a median of 14 months after treatment initiation. Hybrid amino acid PET/MRI using the tracer O-(2-[18F]fluoroethyl)-L-tyrosine, a network-based cortical parcellation, and advanced tractography were used to generate whole-brain fiber count-weighted connectivity matrices. The matrices were applied to a cross-validated machine-learning model to identify predictive fiber connections (edges), critical cortical regions (nodes), and the networks underlying cognitive performance.
Results: Compared to healthy controls (n = 121), patients' cognitive scores were significantly lower in 9 cognitive tests. The models predicted the scores of 7/10 tests (median correlation coefficient, 0.47; range, 0.39-0.57) from 0.6% to 5.4% of the matrix entries; 84% of the predictive edges were between nodes of different networks. Critically involved cortical regions (≥10 adjacent edges) included predominantly left-sided nodes of the visual, somatomotor, dorsal/ventral attention, and default mode networks. Highly critical nodes (≥15 edges) included the default mode network's left temporal and bilateral posterior cingulate cortex.
Conclusions: These results suggest that the cognitive performance of pretreated glioma patients is strongly related to structural connectivity between multiple brain networks and depends on the integrity of known network hubs also involved in other neurological disorders.

Keywords:  brain networks; cognitive functions; diffusion-weighted imaging; glioma; structural connectivity

DOI:  https://doi.org/10.1093/noajnl/vdad151
Front Immunol. 2023 ;14 1297932

Antigen presentation deficiency, mesenchymal differentiation, and resistance to immunotherapy in the murine syngeneic CT2A tumor model.

J Bryan Iorgulescu, Neil Ruthen, Ryuhjin Ahn, Eleni Panagioti, Prafulla C Gokhale, Martha Neagu, Maria C Speranza, Benjamin K Eschle, Kara M Soroko, Raziye Piranlioglu, Meenal Datta, Shanmugarajan Krishnan, Kathleen B Yates, Gregory J Baker, Rakesh K Jain, Mario L Suvà, Donna Neuberg, Forest M White, E Antonio Chiocca, Gordon J Freeman, Arlene H Sharpe, Catherine J Wu, David A Reardon.

   Background: The GL261 and CT2A syngeneic tumor lines are frequently used as immunocompetent orthotopic mouse models of human glioblastoma (huGBM) but demonstrate distinct differences in their responses to immunotherapy.
Methods: To decipher the cell-intrinsic mechanisms that drive immunotherapy resistance in CT2A-luc and to define the aspects of human cancer biology that these lines can best model, we systematically compared their characteristics using whole exome and transcriptome sequencing, and protein analysis through immunohistochemistry, Western blot, flow cytometry, immunopeptidomics, and phosphopeptidomics.
Results: The transcriptional profiles of GL261-luc2 and CT2A-luc tumors resembled those of some huGBMs, despite neither line sharing the essential genetic or histologic features of huGBM. Both models exhibited striking hypermutation, with clonal hotspot mutations in RAS genes (Kras p.G12C in GL261-luc2 and Nras p.Q61L in CT2A-luc). CT2A-luc distinctly displayed mesenchymal differentiation, upregulated angiogenesis, and multiple defects in antigen presentation machinery (e.g. Tap1 p.Y488C and Psmb8 p.A275P mutations) and interferon response pathways (e.g. copy number losses of loci including IFN genes and reduced phosphorylation of JAK/STAT pathway members). The defect in MHC class I expression could be overcome in CT2A-luc by interferon-γ treatment, which may underlie the modest efficacy of some immunotherapy combinations. Additionally, CT2A-luc demonstrated substantial baseline secretion of the CCL-2, CCL-5, and CCL-22 chemokines, which play important roles as myeloid chemoattractants.
Conclusion: Although the clinical contexts that can be modeled by GL261 and CT2A for huGBM are limited, CT2A may be an informative model of immunotherapy resistance due to its deficits in antigen presentation machinery and interferon response pathways.

Keywords:  antigen presentation machinery; cancer; glioblastoma; immunotherapy; mesenchymal; mouse model; resistance

DOI:  https://doi.org/10.3389/fimmu.2023.1297932