Green, Jordan J.

Abstract Spontaneously arising canine high-grade gliomas (cHGG) offer a clinically relevant model for human glioblastoma, sharing conserved histopathological, genetic, and immunological traits. We established two cHGG cell lines and two canine adipose-derived mesenchymal stem cell (cAMSC) lines, and immune-competent 3D cHGG organoid models. Immunoblotting of cHGG cell lines showed that these models exhibit hallmark GBM features including SOX2, Nestin, GFAP, and activation of PI3K/AKT and p53 pathways. Given the established cytotoxic and differentiation-inducing effects of BMP4 in human GBM cell lines, we evaluated whether our canine glioma models recapitulate these responses to assess their translational relevance. BMP4 treatment of cHGG cells induced significant cytotoxicity and reduced migration, accompanied by downregulation of SOX2 and Nestin, upregulation of GFAP, and suppression of CDK6 and phospho-AKT—hallmarks of reduced stemness and astrocytic differentiation. In human-derived GBM cells, BMP4 enhanced radiosensitivity, likely via differentiation and depletion of therapy-resistant stem-like populations. Our cHGG models mirrored these molecular responses, suggesting a conserved BMP4 signaling axis in canine glioma. Quantitative phase imaging showed that BMP4 treatment was non-toxic to cAMSCs and did not impair their migration, supporting the feasibility of engineering cAMSC-BMP4 for therapeutic delivery. Observed molecular traits in canine and human gliomas—including mutually exclusive mutations in PDGFRA and PIK3CA, and shared expression of TP53, PTEN, p21, Rb1, mTOR, and MAPK—underscore the translational relevance of the cHGG model. High-content imaging further confirmed expression of p-AKT, p53, MDM2, and CD44 in cHGG lines, reinforcing activation of conserved gliomagenic pathways. To complement these findings, we developed a cHGG 3D organoids from freshly resected tumors, that recapitulate tumor heterogeneity with co-localized GFAP+/Nestin+ glioma cells, CD3+ infiltrating T cells, macrophages and cleaved caspase-3+ apoptotic cells, indicating active immune surveillance and ongoing programmed cell death. Our results support canine GBM model as a platform to assess glioma biology, cell therapy, and modeling immune engagement in a species-relevant, physiologically intact environment for streamlined translation of therapeutics to human clinical trials.

Background/Objectives: CSCs are critical drivers of the tumor and stem cell phenotypes of glioblastoma (GBM) cells. Chromatin modifications play a fundamental role in driving a GBM CSC phenotype. The goal of this study is to further our understanding of how stem cell-driving events control changes in chromatin architecture that contribute to the tumor-propagating phenotype of GBM. Methods: We utilized computational analyses to identify a subset of clinically relevant genes that were predicted to be repressed in a Polycomb repressive complex 2 (PRC2)-dependent manner in GBM upon induction of stem cell-driving events. These associations were validated in patient-derived GBM neurosphere models using state-of-the-art molecular techniques to express, silence, and measure microRNA (miRNA) and gene expression changes. Advanced Poly(β-amino ester) nanoparticle formulations (PBAEs) were used to deliver miRNAs in vivo to orthotopic human GBM tumor models. Results: We show that glioma stem cell (GSC) formation and tumor propagation involve the crosstalk between multiple epigenetic mechanisms, resulting in the repression of the miRNAs that regulate PRC2 function and histone H3 lysine 27 tri-methylation (H3K27me3). We also identified miR-217-5p as an EZH2 regulator repressed in GSCs and showed that miR-217-5p reconstitution using advanced nanoparticle formulations re-activates the PRC2-repressed genes, inhibits GSC formation, impairs tumor growth, and enhances the effects of ionizing radiation in an orthotopic model of GBM. Conclusions: These findings suggest that inhibiting PRC2 function by targeting EZH2 with miR-217-5p advanced nanoparticle formulations could have a therapeutic benefit in GBM.

Abstract Despite aggressive therapy consisting of surgery followed by radio/chemotherapy Glioblastoma (GBM) recurs in almost all patients and, currently, there are no proven therapies to treat recurrent GBM (rGBM). Recent developments in nanomedicine provide new and promising opportunities to develop new targeted therapeutics to treat brain tumors. In this study we combine bioinformatics, forward-thinking understanding of miRNA biology and cutting-edge nucleic acid delivery vehicles to advance targeted therapeutics for rGBM. Bioinformatic analysis of RNA sequencing from GSCs and clinical rGBM specimens identified TGF-beta receptor II (TGFBR2) signaling as a targetable pathway in rGBM. Mechanistically, we show that alterations in chromatin state driven by stem-cell driving events are conducive to a therapy-resistant state induced by TGFBR2. We show that blocking TGFBR2 via molecular and pharmacological approaches decreases the stem cell capacity, cell viability and re-sensitizes clinical rGBM isolates to temozolomide (TMZ) in vitro. Network analysis of SMAD2/3 targets enriched in rGBM predicted a subset of miRNAs that can target multiple genes within this set. Notably, miR-590-3p was predicted to inhibit 37 SMAD 2/3 gene targets that are also enriched in rGBMs. Bioinformatics analysis also showed that expression of 24 of those 37 miR-590-3p targets are positively correlated with TGFBR2 expression in rGBM clinical specimens. Consistent with these predictions, miR-590-3p inhibited expression of 25 of the 37 targets across 3 distinct therapy-resistant GSC isolates. To translate these in vitro finding, we developed novel bioreducible Lipophilic poly(β-amino ester) nanoparticles (LiPBAEs) for in vivo miRNA delivery. Following direct intratumoral infusion, these nanomiRs efficiently distribute through the tumors and spatial transcriptomic analysis (STA) found a decrease in 34 out of the 37 miR- 590-3p targets in animals that received the active nanomiR compared to control miRNA. Furthermore, STA identified 3 cell populations with distinct transcriptomic profiles reflecting a gradient pharmacodynamic response within tumors that received miR-590-3p nanomiRs with decreasing target expression towards the core of the tumor closest to catheter tip placement. To test the effect of 590-3p nanomiR therapy on survival, animals bearing pre-established intracranial rGBM xenografts received three infusions of either control or miR-590-3p nanomiRs every other day beginning on post-implantation day 7. All 10 animals treated with control nanomiRs were either dead or premorbid requiring euthanasia by post-implantation day 23. In contrast, 3 of 10 animals treated with miR-590-3p nanomiRs remained alive and healthy by post-implantation day 45, at which time the experiment was terminated. These results show that miRNA-based targeted therapeutics provide new opportunities to treat rGBM and bypass the resistance that is developed to standard of care. Citation Format: Hernando Lopez-Bertoni, Jack Korleski, Sophie Sall, Kathryn Luly, Maya K Johnson, Amanda L Johnson, Harmon Khela, Bachchu Lal, TC Taylor, Jean Micheal Ashby, Hector Alonso, Alice Li, Stephany Tzeng, John Laterra, Jordan J Green. Multipronged SMAD Pathway Targeting by LiPBAE miR-590-3p NanomiRs Inhibits Recurrent Glioblastoma Growth and Prolongs Survival [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr PR011.

BACKGROUND AND OBJECTIVES: Despite standard of care with maximal safe resection and chemoradiation, glioblastoma (GBM) is the most common and aggressive type of primary brain cancer. Surgical resection provides a window of opportunity to locally treat gliomas while the patient is recovering and before initiating concomitant chemoradiation. The objective was to assess the safety and establish the maximum tolerated dose of adipose-derived mesenchymal stem cells (AMSCs) for the treatment of recurrent GBM. Secondary objectives were to assess the toxicity profile and long-term survival outcomes of patients enrolled in the trial. In addition, biospecimens will be collected to explore the local and systemic responses to this therapy. METHODS: We will conduct a phase 1, dose-escalated, nonrandomized, open-label, clinical trial of patients with GBM who are undergoing surgical resection for recurrence. Up to 18 patients will receive intracavitary application of AMSCs encapsulated in fibrin glue during surgical resection. All patients will be followed for up to 5 years for safety and survival data. Adverse events will be recorded using the CTCAE V5.0. EXPECTED OUTCOMES: This study will explore the maximum tolerated dose of AMSCs along with the toxicity profile of this therapy in patients with recurrent GBM. In addition, preliminary long-term survival and progression-free survival outcome analysis will be used to power further randomized studies. Finally, cerebrospinal fluid and blood will be obtained throughout the treatment period to investigate circulating molecular and inflammatory tumoral/stem cell markers and explore the mechanism of action of the therapeutic intervention. DISCUSSION: This prospective translational study will determine the initial safety and toxicity profile of local delivery of AMSCs for recurrent GBM. It will also provide additional survival metrics for future randomized trials.

Abstract Confounding results of engineered mesenchymal stem cells (MSCs) used as cellular vehicles has plagued technologies whereby success or failure of novel approaches may be dismissed or inaccurately ascribed solely to the biotechnology platform rather than suitability of the human donor. Polymeric materials were screened for non‐viral engineering of MSCs from multiple human donors to deliver bone morphogenic protein‐4 (BMP4), a protein previously investigated in clinical trials for glioblastoma (GBM) to combat a subpopulation of highly invasive and tumorigenic clones. A “smart technology” that target the migratory and stem‐like nature of GBM will require: (1) a cellular vehicle (MSC) which can scavenge and target residual cells left behind after surgical debulking and deliver; (2) anti‐glioma cargo (BMP4). Multiple MSC donors are safely engineered, though varied in susceptibility to accept BMP4 due to intrinsic characteristics revealed by their molecular signatures. Efficiency is compared via secretion, downstream signaling, differentiation, and anti‐proliferative properties across all donors. In a clinically relevant resection and recurrence model of patient‐derived human GBM, we demonstrate that nanoengineered MSCs are not “donor agnostic” and efficacy is influenced by the inherent suitability of the MSC to the cargo. Therefore, donor profiles hold greater influence in determining downstream outcomes than the technical capabilities of the engineering technology.

OBJECTIVE The vertebral column is the most common site for skeletal metastasis, often leading to debilitating pain and weakness. Metastatic cancer has unique genetic drivers that potentiate tumorigenicity. There is an unmet need for novel targeted therapy in patients with spinal metastatic disease. METHODS The authors assessed the effect of verteporfin-induced yes-associated protein (YAP) inhibition on spine metastatic cell tumorigenicity and radiation sensitivity in vitro. Animal studies used a subcutaneous xenograft mouse model to assess the use of systemic intraperitoneal verteporfin (IP-VP) and intratumoral verteporfin microparticles (IT-VP) to inhibit the tumorigenicity of lung and breast spinal metastatic tumors from primary patient-derived tissue. RESULTS Verteporfin led to a dose-dependent decrease in migration, clonogenicity, and cell viability via inhibition of YAP and downstream effectors cyclin D1, CTGF, TOP2A, ANDRD1, MCL-1, FOSL2, KIF14, and KIF23. This was confirmed with knockdown of YAP. Verteporfin has an additive response when combined with radiation, and knockdown of YAP rendered cells more sensitive to radiation. The addition of verteporfin to YAP knockdown cells did not significantly alter migration, clonogenicity, or cell viability. IP-VP and IT-VP led to diminished tumor growth (p < 0.0001), especially when combined with radiation (p < 0.0001). Tissue analysis revealed diminished expression of YAP (p < 0.0001), MCL-1 (p < 0.0001), and Ki-67 (p < 0.0001) in tissue from verteporfin-treated tumors compared with vehicle-treated tumors. CONCLUSIONS This is the first study to demonstrate that verteporfin-mediated inhibition of YAP leads to diminished tumorigenicity in lung and breast spinal metastatic cancer cells. Targeting of YAP with verteporfin offers promising results that could be translated to human clinical trials.

Abstract A small population of self-renewing stem cells initiate tumors and maintain therapeutic resistance in glioblastoma (GBM). Given the limited treatment options and dismal prognosis for this disease, there is urgent need to identify drivers of stem cells that could be druggable targets. Previous work showed that the endosomal pH regulator NHE9 is upregulated in GBM and correlates with worse survival prognosis. Here, we probed for aberrant signaling pathways in patient-derived GBM cells and found that NHE9 increases cell surface expression and phosphorylation of multiple receptor tyrosine kinases (RTKs) by promoting their escape from lysosomal degradation. Downstream of NHE9-mediated receptor activation, oncogenic signaling pathways converged on the JAK2-STAT3 transduction axis to induce pluripotency genes Oct4 and Nanog and suppress markers of glial differentiation. We used both genetic and chemical approaches to query the role of endosomal pH in GBM phenotypes. Loss-of-function mutations in NHE9 that failed to alkalinize endosomal lumen did not increase self-renewal capacity of gliomaspheres in vitro. However, monensin, a chemical mimetic of Na+/H+ exchanger activity, and the H+ pump inhibitor bafilomycin bypassed NHE9 to directly alkalinize the endosomal lumen resulting in stabilization of RTKs and induction of Oct4 and Nanog. Using orthotopic models of primary GBM cells we found that NHE9 increased tumor initiation in vivo. We propose that NHE9 initiates inside-out signaling from the endosomal lumen, distinct from the established effects of cytosolic and extracellular pH on tumorigenesis. Endosomal pH may be an attractive therapeutic target that diminishes stemness in GBM, agnostic of specific receptor subtype.

AbstractClinical translation of polymer‐based nanocarriers for systemic delivery of RNA has been limited due to poor colloidal stability in the blood stream and intracellular delivery of the RNA to the cytosol. To address these limitations, this study reports a new strategy incorporating photocrosslinking of bioreducible nanoparticles for improved stability extracellularly and rapid release of RNA intracellularly. In this design, the polymeric nanocarriers contain ester bonds for hydrolytic degradation and disulfide bonds for environmentally triggered small interfering RNA (siRNA) release in the cytosol. These photocrosslinked bioreducible nanoparticles (XbNPs) have a shielded surface charge, reduced adsorption of serum proteins, and enable superior siRNA‐mediated knockdown in both glioma and melanoma cells in high‐serum conditions compared to non‐crosslinked formulations. Mechanistically, XbNPs promote cellular uptake and the presence of secondary and tertiary amines enables efficient endosomal escape. Following systemic administration, XbNPs facilitate targeting of cancer cells and tissue‐mediated siRNA delivery beyond the liver, unlike conventional nanoparticle‐based delivery. These attributes of XbNPs facilitate robust siRNA‐mediated knockdown in vivo in melanoma tumors colonized in the lungs following systemic administration. Thus, biodegradable polymeric nanoparticles, via photocrosslinking, demonstrate extended colloidal stability and efficient delivery of RNA therapeutics under physiological conditions, and thereby potentially advance systemic delivery technologies for nucleic acid‐based therapeutics.

AbstractBrain cancer persists as a difficult‐to‐treat condition. In particular, metastatic brain cancer and malignant primary brain tumors such as glioblastoma (GBM) are among the most deadly and still carry a dismal prognosis despite current standard of care with surgery and chemo‐radiation. Recent advances in nanotechnology have led to innovative nanomedicine strategies for the treatment of brain cancers and specifically for GBM. These strategies represent promising alternative or adjunctive therapies for conventional treatment modalities and are increasingly designed to target specific cell types such as brain tumor‐initiating cells and immune cells. This review provides an update on emerging insights into these nanomedicine strategies with a focus on nanoparticles as tools that facilitate 1) drug delivery 2) gene therapy, and 3) engineered‐cellular therapy for GBM and future directions for brain cancer treatment.