Functional Characterization of Brain Tumor-Initiating Cells and Establishment of GBM Preclinical Models that Incorporate Heterogeneity, Therapy, and Sex Differences

USP9X deubiquitinates TRRAP to promote glioblastoma cell proliferation and migration and M2 macrophage polarization

Glioblastoma (GBM) is the most aggressive form of brain cancer, characterized by rapid growth and invasion into surrounding brain tissue. Ubiquitin-specific protease 9X (USP9X) has emerged as a key regulator in various cancers, but its role in GBM pathogenesis remains unclear. Understanding the molecular mechanisms underlying USP9X modulation of GBM progression could unveil potential therapeutic targets for this deadly disease. The mRNA and protein levels were determined in GBM tissues and/or cells using quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting assays, respectively. Cell migration was evaluated through wound-healing assay, while cell proliferation was measured using colony formation and CCK-8 assays. Flow cytometry analysis was performed to quantify the CD206-positive macrophages to assess M2 polarization. Co-immunoprecipitation (Co-IP) assays were conducted to elucidate the association between USP9X and transformation/transcription domain-associated protein (TRRAP). Cycloheximide (CHX) treatment was used to determine the impact of USP9X on TRRAP protein stabilization. Furthermore, the effect of USP9X depletion on GBM cell malignancy was validated using a xenograft mouse model. We found that USP9X expression was elevated in GBM tissues and cells. Depletion of USP9X suppressed GBM cell migration, proliferation, and M2 macrophage polarization. Mechanistically, USP9X stabilized TRRAP through the deubiquitination pathway in GBM cells, and TRRAP mitigated the effects of USP9X silencing on GBM cell malignant phenotypes and M2 macrophage polarization. Moreover, silencing of USP9X inhibited tumor formation in vivo. Together, USP9X deubiquitinated TRRAP, thereby promoting glioblastoma cell proliferation, migration, and M2 macrophage polarization. These results highlight the potential of targeting the USP9X-TRRAP axis as a therapeutic strategy for GBM.

Solid cancer-directed CAR T cell therapy that attacks both tumor and immunosuppressive cells via targeting PD-L1

Chimeric antigen receptor (CAR) T cell therapy has encountered limited success in solid tumors. The lack of dependable antigens and the immunosuppressive tumor microenvironment (TME) are major challenges. Within the TME, tumor cells along with immunosuppressive cells employ an immune-evasion mechanism that upregulates programmed death ligand 1 (PD-L1) to deactivate effector T cells; this makes PD-L1 a reliable, universal target for solid tumors. We developed a novel PD-L1 CAR (MC9999) using our humanized anti-PD-L1 monoclonal antibody, designed to simultaneously target tumor and immunosuppressive cells. The antigen-specific antitumor effects of MC9999 CAR T cells were observed consistently across four solid tumor models: breast cancer, lung cancer, melanoma, and glioblastoma multiforme (GBM). Notably, intravenous administration of MC9999 CAR T cells eradicated intracranially established LN229 GBM tumors, suggesting penetration of the blood-brain barrier. The proof-of-concept data demonstrate the cytolytic effect of MC9999 CAR T cells against immunosuppressive cells, including microglia HMC3 cells and M2 macrophages. Furthermore, MC9999 CAR T cells elicited cytotoxicity against primary tumor-associated macrophages within GBM tumors. The concept of targeting both tumor and immunosuppressive cells with MC9999 was further validated using CAR T cells derived from cancer patients. These findings establish MC9999 as a foundation for the development of effective CAR T cell therapies against solid tumors.

Cell-specific cross-talk proteomics reveals cathepsin B signaling as a driver of glioblastoma malignancy near the subventricular zone

Glioblastoma (GBM) is the most prevalent and aggressive malignant primary brain tumor. GBM proximal to the lateral ventricles (LVs) is more aggressive, potentially because of subventricular zone contact. Despite this, cross-talk between GBM and neural stem/progenitor cells (NSC/NPCs) is not well understood. Using cell-specific proteomics, we show that LV-proximal GBM prevents neuronal maturation of NSCs through induction of senescence. In addition, GBM brain tumor-initiating cells (BTICs) increase expression of cathepsin B (CTSB) upon interaction with NPCs. Lentiviral knockdown and recombinant protein experiments reveal that both cell-intrinsic and soluble CTSB promote malignancy-associated phenotypes in BTICs. Soluble CTSB stalls neuronal maturation in NPCs while promoting senescence, providing a link between LV-tumor proximity and neurogenesis disruption. Last, we show LV-proximal CTSB up-regulation in patients, showing the relevance of this cross-talk in human GBM biology. These results demonstrate the value of proteomic analysis in tumor microenvironment research and provide direction for new therapeutic strategies in GBM.

From the Operating Room to the Laboratory: Role of the Neuroscience Tissue Biorepository in the Clinical, Translational, and Basic Science Research Pipeline

OBJECTIVE

To establish a neurologic disorder-driven biospecimen repository to bridge the operating room with the basic science laboratory and to generate a feedback cycle of increased institutional and national collaborations, federal funding, and human clinical trials.

METHODS

Patients were prospectively enrolled from April 2017 to July 2022. Tissue, blood, cerebrospinal fluid, bone marrow aspirate, and adipose tissue were collected whenever surgically safe. Detailed clinical, imaging, and surgical information was collected. Neoplastic and nonneoplastic samples were categorized and diagnosed in accordance with current World Health Organization classifications and current standard practices for surgical pathology at the time of surgery.

RESULTS

A total of 11,700 different specimens from 813 unique patients have been collected, with 14.2% and 8.5% of patients representing ethnic and racial minorities, respectively. These include samples from a total of 463 unique patients with a primary central nervous system tumor, 88 with metastasis to the central nervous system, and 262 with nonneoplastic diagnoses. Cerebrospinal fluid and adipose tissue dedicated banks with samples from 130 and 16 unique patients, respectively, have also been established. Translational efforts have led to 42 new active basic research projects; 4 completed and 6 active National Institutes of Health-funded projects; and 2 investigational new drug and 5 potential Food and Drug Administration-approved phase 0/1 human clinical trials, including 2 investigator initiated and 3 industry sponsored.

CONCLUSION

We established a comprehensive biobank with detailed notation with broad potential that has helped us to transform our practice of research and patient care and allowed us to grow in research and clinical trials in addition to providing a source of tissue for new discoveries.

Stabilization of KPNB1 by deubiquitinase USP7 promotes glioblastoma progression through the YBX1-NLGN3 axis

BACKGROUND

Glioblastoma (GBM) is the most common malignant tumor of the central nervous system. It is an aggressive tumor characterized by rapid proliferation, diffuse tumor morphology, and poor prognosis. Unfortunately, current treatments, such as surgery, radiotherapy, and chemotherapy, are unable to achieve good outcomes. Therefore, there is an urgent need to explore new treatment targets. A detailed mechanistic exploration of the role of the nuclear pore transporter KPNB1 in GBM is lacking. This study demonstrated that KPNB1 regulated GBM progression through a transcription factor YBX1 to promote the expression of post-protrusion membrane protein NLGN3. This regulation was mediated by the deubiquitinating enzyme USP7.

METHODS

A tissue microarray was used to measure the expression of KPNB1 and USP7 in glioma tissues. The effects of KPNB1 knockdown on the tumorigenic properties of glioma cells were characterized by colony formation assays, Transwell migration assay, EdU proliferation assays, CCK-8 viability assays, and apoptosis analysis using flow cytometry. Transcriptome sequencing identified NLGN3 as a downstream molecule that is regulated by KPNB1. Mass spectrometry and immunoprecipitation were performed to analyze the potential interaction between KPNB1 and YBX1. Moreover, the nuclear translocation of YBX1 was determined with nuclear-cytoplasmic fractionation and immunofluorescence staining, and chromatin immunoprecipitation assays were conducted to study DNA binding with YBX1. Ubiquitination assays were performed to determine the effects of USP7 on KPNB1 stability. The intracranial orthotopic tumor model was used to detect the efficacy in vivo.

RESULTS

In this study, we found that the nuclear receptor KPNB1 was highly expressed in GBM and could mediate the nuclear translocation of macromolecules to promote GBM progression. Knockdown of KPNB1 inhibited the progression of GBM, both in vitro and in vivo. In addition, we found that KPNB1 could regulate the downstream expression of Neuroligin-3 (NLGN3) by mediating the nuclear import of transcription factor YBX1, which could bind to the NLGN3 promoter. NLGN3 was necessary and sufficient to promote glioma cell growth. Furthermore, we found that deubiquitinase USP7 played a critical role in stabilizing KPNB1 through deubiquitination. Knockdown of USP7 expression or inhibition of its activity could effectively impair GBM progression. In vivo experiments also demonstrated the promoting effects of USP7, KPNB1, and NLGN3 on GBM progression. Overall, our results suggested that KPNB1 stability was enhanced by USP7-mediated deubiquitination, and the overexpression of KPNB1 could promote GBM progression via the nuclear translocation of YBX1 and the subsequent increase in NLGN3 expression.

CONCLUSION

This study identified a novel and targetable USP7/KPNB1/YBX1/NLGN3 signaling axis in GBM cells.

Behavior of glioblastoma brain tumor stem cells following a suborbital rocket flight: reaching the "edge" of outer space

The emerging arena of space exploration has created opportunities to study cancer cell biology in the environments of microgravity and hypergravity. Studying cellular behavior in altered gravity conditions has allowed researchers to make observations of cell function that would otherwise remain unnoticed. The patient-derived QNS108 brain tumor initiating cell line (BTIC), isolated from glioblastoma (GBM) tissue, was launched on a suborbital, parabolic rocket flight conducted by EXOS Aerospace Systems & Technologies. All biologicals and appropriate ground controls were secured post-launch and transported back to our research facility. Cells from the rocket-flight and ground-based controls were isolated from the culture containers and expanded on adherent flasks for two weeks. In vitro migration, proliferation, and stemness assays were performed. Following cell expansion, male nude mice were intracranially injected with either ground-control (GC) or rocket-flight (RF) exposed cells to assess tumorigenic capacity (n = 5 per group). Patient-derived QNS108 BTICs exposed to RF displayed more aggressive tumor growth than the GC cells in vitro and in vivo. RF cells showed significantly higher migration (p < 0.0000) and stemness profiles (p < 0.01) when compared to GC cells. Further, RF cells, when implanted in vivo in the brain of rodents had larger tumor-associated cystic growth areas (p = 0.00029) and decreased survival (p = 0.0172) as compared to those animals that had GC cells implanted.

Magnetic resonance imaging findings of intracranial extraventricular ependymoma: A retrospective multi-center cohort study of 114 cases

BACKGROUND

Intracranial extraventricular ependymoma (IEE) is an ependymoma located in the brain parenchyma outside the ventricles. IEE has overlapping clinical and imaging characteristics with glioblastoma multiforme (GBM) but different treatment strategy and prognosis. Therefore, an accurate preoperative diagnosis is necessary for optimizing therapy for IEE.

METHODS

A retrospective multicenter cohort of IEE and GBM was identified. MR imaging characteristics assessed with the Visually Accessible Rembrandt Images (VASARI) feature set and clinicopathological findings were recorded. Independent predictors for IEE were identified using multivariate logistic regression, which was used to construct a diagnostic score for differentiating IEE from GBM.

RESULTS

Compared to GBM, IEE tended to occur in younger patients. Multivariate logistic regression analysis identified seven independent predictors for IEE. Among them, 3 predictors including tumor necrosis rate (F7), age, and tumor-enhancing margin thickness (F11), demonstrated higher diagnostic performance with an Area Under Curve (AUC) of more than 70% in distinguishing IEE from GBM. The AUC was 0.85, 0.78, and 0.70, with sensitivity of 92.98%, 72.81%, and 96.49%, and specificity of 65.50%, 73.64%, and 43.41%, for F7, age, and F11, respectively.

CONCLUSION

We identified specific MR imaging features such as tumor necrosis and thickness of enhancing tumor margins that could help to differentiate IEE from GBM. Our study results should be helpful to assist in diagnosis and clinical management of this rare brain tumor.

Perivascular invasion of primary human glioblastoma cells in organotypic human brain slices: human cells migrating in human brain

INTRODUCTION

Glioblastoma (GBM) is an aggressive primary brain cancer. Lack of effective therapy is related to its highly invasive nature. GBM invasion has been studied with reductionist systems that do not fully recapitulate the cytoarchitecture of the brain. We describe a human-derived brain organotypic model to study the migratory properties of GBM IDH-wild type ex vivo.

METHODS

Non-tumor brain samples were obtained from patients undergoing surgery (n = 7). Organotypic brain slices were prepared, and green fluorescent protein (GFP)-labeled primary human GBM IDH-wild type cells (GBM276, GBM612, GBM965) were placed on the organotypic slice. Migration was evaluated via microscopy and immunohistochemistry.

RESULTS

After placement, cells migrated towards blood vessels; initially migrating with limited directionality, sending processes in different directions, and increasing their speed upon contact with the vessel. Once merged, migration speed decreased and continued to decrease with time (p < 0.001). After perivascular localization, migration is limited along the blood vessels in both directions. The percentage of cells that contact blood vessels and then continue to migrate along the vessel was 92.5% (- 3.9/ + 2.9)% while the percentage of cells that migrate along the blood vessel and leave was 7.5% (- 2.9/ + 3.9) (95% CI, Clopper-Pearson (exact); n = 256 cells from six organotypic cultures); these percentages are significantly different from the random (50%) null hypothesis (z = 13.6; p < 10-7). Further, cells increase their speed in response to a decrease in oxygen tension from atmospheric normoxia (20% O2) to anoxia (1% O2) (p = 0.033).

CONCLUSION

Human organotypic models can accurately study cell migration ex vivo. GBM IDH-wild type cells migrate toward the perivascular space in blood vessels and their migratory parameters change once they contact vascular structures and under hypoxic conditions. This model allows the evaluation of GBM invasion, considering the human brain microenvironment when cells are removed from their native niche after surgery.

Advances in computational and translational approaches for malignant glioma

Gliomas are the most common primary brain tumors in adults and carry a dismal prognosis for patients. Current standard-of-care for gliomas is comprised of maximal safe surgical resection following by a combination of chemotherapy and radiation therapy depending on the grade and type of tumor. Despite decades of research efforts directed towards identifying effective therapies, curative treatments have been largely elusive in the majority of cases. The development and refinement of novel methodologies over recent years that integrate computational techniques with translational paradigms have begun to shed light on features of glioma, previously difficult to study. These methodologies have enabled a number of point-of-care approaches that can provide real-time, patient-specific and tumor-specific diagnostics that may guide the selection and development of therapies including decision-making surrounding surgical resection. Novel methodologies have also demonstrated utility in characterizing glioma-brain network dynamics and in turn early investigations into glioma plasticity and influence on surgical planning at a systems level. Similarly, application of such techniques in the laboratory setting have enhanced the ability to accurately model glioma disease processes and interrogate mechanisms of resistance to therapy. In this review, we highlight representative trends in the integration of computational methodologies including artificial intelligence and modeling with translational approaches in the study and treatment of malignant gliomas both at the point-of-care and outside the operative theater in silico as well as in the laboratory setting.

Epigenetic modifiers either individually or in specific combinations impair viability of patient-derived glioblastoma cell line while exhibit moderate effect on normal stem cells growth

Glioblastomas (GBM), also known as glioblastoma multiforme, are the most aggressive type of brain cancer. Currently, there is no effective treatment for GBM, highlighting the pressing need for new therapeutic strategies. In a recent study, we demonstrated that specific combinations of epigenetic modifiers significantly affect the metabolism and proliferation rate of the two most aggressive GBM cell lines, D54 and U-87. Importantly, these combinations exhibited minimal effects on the growth of normal stem cells. In this study, we extended our investigation to include a patient-derived GBM stem cell line. Our results showed that the combinations of modulators of histone and DNA covalent modifying enzymes that synergistically suppress D54 and U87 cell line growth also impair the viability of the patient-derived GBM stem cell line. These findings suggest that epigenetic modifiers alone or in specific combinations exhibit a cytotoxic effect on established and low-passage patient-derived GBM cell lines, and thus could be a promising therapeutic approach for this type of brain cancer.

Radiation combined with oncolytic vaccinia virus provides pronounced antitumor efficacy and induces immune protection in an aggressive glioblastoma model

Glioblastoma (GB) is a malignant and immune-suppressed brain cancer that remains incurable despite the current standard of care. Radiotherapy is a mainstay of GB treatment, however invasive cancer cells outside the irradiated field and radioresistance preclude complete eradication of GB cells. Oncolytic virus therapy harnesses tumor-selective viruses to spread through and destroy tumors while stimulating antitumor immune responses, and thus has potential for use following radiotherapy. We demonstrate that oncolytic ΔF4LΔJ2R vaccinia virus (VACV) replicates in and induces cytotoxicity of irradiated brain tumor initiating cells in vitro. Importantly, a single 10 Gy dose of radiation combined with ΔF4LΔJ2R VACV produced considerably superior anticancer effects relative to either monotherapy when treating immune-competent orthotopic CT2A-luc mouse models-significantly extending survival and curing the majority of mice. Mice cured by the combination displayed significantly increased survival relative to naïve age-matched controls following intracranial tumor challenge, with some complete rejections. Further, the combination therapy was associated with an increased ratio of CD8⁺ effector T cells to regulatory T cells compared to either monotherapy. This study validates the use of radiation with an oncolytic ΔF4LΔJ2R VACV to improve treatment of this malignant brain cancer.

Epigenetic modifiers either individually or in specific combinations impair viability of patient-derived glioblastoma cell line while exhibiting moderate effect on normal stem cells growth

Glioblastomas (GBM), also known as glioblastoma multiforme, are the most aggressive type of brain cancers. Currently, there is no real treatment for GBM and thus there is a compelling need for new therapeutic strategies for such type of cancers. Recently, we demonstrated that specific combinations of epigenetic modifiers significantly affect the metabolism and proliferation rate of two most aggressive GBM cell lines D54 and U-87. Importantly, these combinations exhibited minimal effect on normal stem cells growth. In this study we demonstrated that the combinations of modulators of histone and DNA covalent modifying enzymes that synergistically suppress D54 and U87 cell lines growth, also impair the viability of a patient freshly-derived GBM stem cell line. These data suggest that epigenetic modifiers alone or in specific combinations exhibit cytotoxic effect on established and low passage patient derived GB cell lines and thus could be a promising therapeutic approach for such type of brain cancers.

Anticancer Properties of Hexosamine Analogs Designed to Attenuate Metabolic Flux through the Hexosamine Biosynthetic Pathway

Altered cellular metabolism is a hallmark of cancer pathogenesis and progression; for example, a near-universal feature of cancer is increased metabolic flux through the hexosamine biosynthetic pathway (HBP). This pathway produces uridine diphosphate N-acetylglucosamine (UDP-GlcNAc), a potent oncometabolite that drives multiple facets of cancer progression. In this study, we synthesized and evaluated peracetylated hexosamine analogs designed to reduce flux through the HBP. By screening a panel of analogs in pancreatic cancer and glioblastoma multiform (GBM) cells, we identified Ac₄Glc2Bz─a benzyl-modified GlcNAc mimetic─as an antiproliferative cancer drug candidate that down-regulated oncogenic metabolites and reduced GBM cell motility at concentrations non-toxic to non-neoplastic cells. More specifically, the growth inhibitory effects of Ac₄Glc2Bz were linked to reduced levels of UDP-GlcNAc and concomitant decreases in protein O-GlcNAc modification in both pancreatic cancer and GBM cells. Targeted metabolomics analysis in GBM cells showed that Ac₄Glc2Bz disturbed glucose metabolism, amino acid pools, and nucleotide precursor biosynthesis, consistent with reduced proliferation and other anti-oncogenic properties of this analog. Furthermore, Ac₄Glc2Bz reduced the invasion, migration, and stemness of GBM cells. Importantly, normal metabolic functions mediated by UDP-GlcNAc were not disrupted in non-neoplastic cells, including maintenance of endogenous levels of O-GlcNAcylation with no global disruption of N-glycan production. Finally, a pilot in vivo study showed that a potential therapeutic window exists where animals tolerated 5- to 10-fold higher levels of Ac₄Glc2Bz than projected for in vivo efficacy. Together, these results establish GlcNAc analogs targeting the HBP through salvage mechanisms as a new therapeutic approach to safely normalize an important facet of aberrant glucose metabolism associated with cancer.

SARS-CoV2 entry factors are expressed in primary human glioblastoma and recapitulated in cerebral organoid models

PURPOSE

Glioblastoma (GBM) is the most common and malignant primary brain tumor in adults with a median overall survival of only 14.6 months despite aggressive treatment. While immunotherapy has been successful in other cancers, its benefit has been proven elusive in GBM, mainly due to a markedly immunosuppressive tumor microenvironment. SARS-CoV-2 has been associated with the development of a pronounced central nervous system (CNS) inflammatory response when infecting different cells including astrocytes, endothelial cells, and microglia. While SARS-CoV2 entry factors have been described in different tissues, their presence and implication on GBM aggressiveness or microenvironment has not been studied on appropriate preclinical models.

METHODS

We evaluated the presence of crucial SARS-CoV-2 entry factors: ACE2, TMPRSS2, and NRP1 in matched surgically-derived GBM tissue, cells lines, and organoids; as well as in human brain derived specimens using immunohistochemistry, confocal pixel line intensity quantification, and transcriptome analysis.

RESULTS

We show that patient derived-GBM tissue and cell cultures express SARS-CoV2 entry factors, being NRP1 the most crucial facilitator of SARS-CoV-2 infection in GBM. Moreover, we demonstrate that, receptor expression remains present in our GBM organoids, making them an adequate model to study the effect of this virus in GBM for the potential development of viral therapies in the future.

CONCLUSION

Our findings suggest that the SARS-CoV-2 virus entry factors are expressed in primary tissues and organoid models and could be potentially utilized to study the susceptibility of GBM to this virus to target or modulate the tumor microenviroment.

Melatonin Treatment Triggers Metabolic and Intracellular pH Imbalance in Glioblastoma

Metabolic rewiring in glioblastoma (GBM) is linked to intra- and extracellular pH regulation. In this study, we sought to characterize the role of melatonin on intracellular pH modulation and metabolic consequences to identify the mechanisms of action underlying melatonin oncostatic effects on GBM tumor initiating cells. GBM tumor initiating cells were treated at different times with melatonin (1.5 and 3.0 mM). We analyzed melatonin’s functional effects on GBM proliferation, cell cycle, viability, stemness, and chemo-radiosensitivity. We then assessed the effects of melatonin on GBM metabolism by analyzing the mitochondrial and glycolytic parameters. We also measured the intracellular and extracellular pH. Finally, we tested the effects of melatonin on a mouse subcutaneous xenograft model. We found that melatonin downregulated LDHA and MCT4, decreasing lactate production and inducing a decrease in intracellular pH that was associated with an increase in ROS and ATP depletion. These changes blocked cell cycle progression and induced cellular death and we observed similar results in vivo. Melatonin’s cytotoxic effects on GBM were due, at least in part, to intracellular pH modulation, which has emerged as a newly identified mechanism, providing new insights into the oncostatic effect of melatonin on GBM.

The Next Frontier in Health Disparities-A Closer Look at Exploring Sex Differences in Glioma Data and Omics Analysis, from Bench to Bedside and Back

Sex differences are increasingly being explored and reported in oncology, and glioma is no exception. As potentially meaningful sex differences are uncovered, existing gender-derived disparities mirror data generated in retrospective and prospective trials, real-world large-scale data sets, and bench work involving animals and cell lines. The resulting disparities at the data level are wide-ranging, potentially resulting in both adverse outcomes and failure to identify and exploit therapeutic benefits. We set out to analyze the literature on women's data disparities in glioma by exploring the origins of data in this area to understand the representation of women in study samples and omics analyses. Given the current emphasis on inclusive study design and research, we wanted to explore if sex bias continues to exist in present-day data sets and how sex differences in data may impact conclusions derived from large-scale data sets, omics, biospecimen analysis, novel interventions, and standard of care management.

The early infiltrative phase of GBM hypothesis: are molecular glioblastomas histological glioblastomas in the making? A preliminary multicenter study

PURPOSE

The presence of necrosis or microvascular proliferation was previously the hallmark for glioblastoma (GBM) diagnosis. The 2021 WHO classification now considers IDH-wildtype diffuse astrocytic tumors without the histological features of glioblastoma (that would have otherwise been classified as grade 2 or 3) as molecular GBM (molGBM) if they harbor any of the following molecular abnormalities: TERT promoter mutation, EGFR amplification, or chromosomal + 7/-10 copy changes. We hypothesize that these tumors are early histological GBM and will eventually develop the classic histological features.

METHODS

Medical records from 65 consecutive patients diagnosed with molGBM at three tertiary-care centers from our institution were retrospectively reviewed from November 2017-October 2021. Only patients who underwent reoperation for tumor recurrence and whose tissue at initial diagnosis and recurrence was available were included in this study. The detailed clinical, histopathological, and radiographic scenarios are presented.

RESULTS

Five patients were included in our final cohort. Three (60%) patients underwent reoperation for recurrence in the primary site and 2 (40%) underwent reoperation for distal recurrence. Microvascular proliferation and pseudopalisading necrosis were absent at initial diagnosis but present at recurrence in 4 (80%) patients. Radiographically, all tumors showed contrast enhancement, however none of them showed the classic radiographic features of GBM at initial diagnosis.

CONCLUSIONS

In this manuscript we present preliminary data for a hypothesis that molGBMs are early histological GBMs diagnosed early in their natural history of disease and will eventually develop necrosis and microvascular proliferation. Further correlative studies are needed in support of this hypothesis.

Identification of Synergistic Drug Combinations to Target KRAS-Driven Chemoradioresistant Cancers Utilizing Tumoroid Models of Colorectal Adenocarcinoma and Recurrent Glioblastoma

Treatment resistance is observed in all advanced cancers. Colorectal cancer (CRC) presenting as colorectal adenocarcinoma (COAD) is the second leading cause of cancer deaths worldwide. Multimodality treatment includes surgery, chemotherapy, and targeted therapies with selective utilization of immunotherapy and radiation therapy. Despite the early success of anti-epidermal growth factor receptor (anti-EGFR) therapy, treatment resistance is common and often driven by mutations in APC, KRAS, RAF, and PI3K/mTOR and positive feedback between activated KRAS and WNT effectors. Challenges in the direct targeting of WNT regulators and KRAS have caused alternative actionable targets to gain recent attention. Utilizing an unbiased drug screen, we identified combinatorial targeting of DDR1/BCR-ABL signaling axis with small-molecule inhibitors of EGFR-ERBB2 to be potentially cytotoxic against multicellular spheroids obtained from WNT-activated and KRAS-mutant COAD lines (HCT116, DLD1, and SW480) independent of their KRAS mutation type. Based on the data-driven approach using available patient datasets (The Cancer Genome Atlas (TCGA)), we constructed transcriptomic correlations between gene DDR1, with an expression of genes for EGFR, ERBB2-4, mitogen-activated protein kinase (MAPK) pathway intermediates, BCR, and ABL and genes for cancer stem cell reactivation, cell polarity, and adhesion; we identified a positive association of DDR1 with EGFR, ERBB2, BRAF, SOX9, and VANGL2 in Pan-Cancer. The evaluation of the pathway network using the STRING database and Pathway Commons database revealed DDR1 protein to relay its signaling via adaptor proteins (SHC1, GRB2, and SOS1) and BCR axis to contribute to the KRAS-PI3K-AKT signaling cascade, which was confirmed by Western blotting. We further confirmed the cytotoxic potential of our lead combination involving EGFR/ERBB2 inhibitor (lapatinib) with DDR1/BCR-ABL inhibitor (nilotinib) in radioresistant spheroids of HCT116 (COAD) and, in an additional devastating primary cancer model, glioblastoma (GBM). GBMs overexpress DDR1 and share some common genomic features with COAD like EGFR amplification and WNT activation. Moreover, genetic alterations in genes like NF1 make GBMs have an intrinsically high KRAS activity. We show the combination of nilotinib plus lapatinib to exhibit more potent cytotoxic efficacy than either of the drugs administered alone in tumoroids of patient-derived recurrent GBMs. Collectively, our findings suggest that combinatorial targeting of DDR1/BCR-ABL with EGFR-ERBB2 signaling may offer a therapeutic strategy against stem-like KRAS-driven chemoradioresistant tumors of COAD and GBM, widening the window for its applications in mainstream cancer therapeutics.

Mechanical Properties in the Glioma Microenvironment: Emerging Insights and Theranostic Opportunities

Gliomas represent the most common malignant primary brain tumors, and a high-grade subset of these tumors including glioblastoma are particularly refractory to current standard-of-care therapies including maximal surgical resection and chemoradiation. The prognosis of patients with these tumors continues to be poor with existing treatments and understanding treatment failure is required. The dynamic interplay between the tumor and its microenvironment has been increasingly recognized as a key mechanism by which cellular adaptation, tumor heterogeneity, and treatment resistance develops. Beyond ongoing lines of investigation into the peritumoral cellular milieu and microenvironmental architecture, recent studies have identified the growing role of mechanical properties of the microenvironment. Elucidating the impact of these biophysical factors on disease heterogeneity is crucial for designing durable therapies and may offer novel approaches for intervention and disease monitoring. Specifically, pharmacologic targeting of mechanical signal transduction substrates such as specific ion channels that have been implicated in glioma progression or the development of agents that alter the mechanical properties of the microenvironment to halt disease progression have the potential to be promising treatment strategies based on early studies. Similarly, the development of technology to measure mechanical properties of the microenvironment in vitro and in vivo and simulate these properties in bioengineered models may facilitate the use of mechanical properties as diagnostic or prognostic biomarkers that can guide treatment. Here, we review current perspectives on the influence of mechanical properties in glioma with a focus on biophysical features of tumor-adjacent tissue, the role of fluid mechanics, and mechanisms of mechanical signal transduction. We highlight the implications of recent discoveries for novel diagnostics, therapeutic targets, and accurate preclinical modeling of glioma.