Russo, Marissa

Abstract The purpose of this study was to identify glioblastoma (GBM) proteins that contribute to the hijacking of the tumor microenvironment through extracellular vesicles (EVs). GBM is the most aggressive primary brain tumor in adults. It presents significant challenges due to its universal recurrence and limited survival rates, exacerbated when its located proximal to the lateral ventricles (LV). The cellular subpopulation of brain tumor-initiating cells (BTICs) plays a pivotal role in tumor initiation and invasiveness, interacting with the microenvironment, particularly the cellular components in the subventricular zone (SVZ) in the LV. We employed an integrated multi-omic strategy combining cell-specific proteomics of EV cargo and whole-cell transcriptomics of EV-treated neural progenitor cells (NPCs) to define mechanisms by which BTICs remodel the tumor microenvironment. Using the TurboID cell-specific protein labeling system, we identified a previously unrecognized repertoire of BTIC-derived proteins selectively packaged into EVs. Among these, DPYSL2 (CRMP2) emerged as a prominent EV cargo as it is implicated in cancer cell migration and invasion. Functionally, exposure of human NPCs to BTIC-derived EVs significantly increased NPC proliferation and migratory capacity in vitro, findings that were recapitulated in vivo following intracranial and intranasal delivery of GBM-derived EVs. To define the molecular basis of these phenotypic changes, we performed RNA sequencing of NPCs following EV treatment. Bioinformatic integration, including ontogenic and pathway enrichment analyses, revealed robust activation of oncogenic signaling pathways, notably JAK/STAT, mTOR, and WNT, accompanied by upregulation of downstream effector genes. Importantly, integrative proteomic-transcriptomic analyses identified DPYSL2 as a mechanistic link between EV cargo and NPC transcriptional reprogramming. Prior studies demonstrate that DPYSL2 can interact with JAK kinases, promoting STAT3 activation and transcription of genes such as Vimentin (VIM) and CALCA, consistent with the transcriptomic changes observed in EV-treated NPCs. Overall, we have identified DPYSL2 as a novel regulator of tumor microenvironment hijacking mediated by extracellular vesicles. This multi-omic approach is the first use of cell-specific proteomics to study extracellular vesicles and the first time pairing this method to identify upstream regulators of transcriptomic changes in neural progenitor cells. Collectively, these findings establish a direct molecular connection between BTIC-derived EV proteins and functional reprogramming of neural progenitor cells, providing mechanistic insight into how glioblastoma exploits developmental programs to promote tumor progression. Citation Format: Marissa Russo, Emily Norton, Weiwei Wang, Shreyartha Mukherjee, Daniel Wickland, TuKiet Lam, Hugo Guerrero-Cazares. DPYSL2 mediates extracellular vesicle-driven reprogramming of the glioblastoma tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(8_Suppl):Abstract nr LB228.

Abstract Glioblastoma (GBM), the most aggressive primary brain tumor in adults, presents significant challenges due to its universal recurrence and limited survival rates, exacerbated when proximal to the lateral ventricles (LV). The subpopulation of brain tumor-initiating cells (BTICs) plays a pivotal role in tumor initiation and invasiveness, interacting with the microenvironment, particularly the cellular components in the subventricular zone (SVZ), like Neural Progenitor Cells (NPCs). Mechanisms of intercellular communication present in the SVZ include paracrine, autocrine, direct cell contact, and more recently extracellular vesicles (EVs). EVs are membrane-bound particles released by cells that are central to intercellular communication. They carry bioactive proteins, RNA, and other molecules that influence recipient cell behavior. This study investigates the role of EVs in GBM’s communication with non-cancer cells. Our findings indicate that BTIC-derived EVs promote migration and proliferation (*p < 0.02, ****p <0.001) in NPCs in vitro, highlighting the EVs’ role in altering the microenvironment. Additionally, we leverage a multi-omic approach to profile the small RNA and protein cargo of BTIC-EVs while also evaluating changes in the transcriptome of NPCs after BTIC-EV treatment. To identify the protein cargo contained in GBM-derived EVs, we utilized the innovative proximity-labeling system TurboID. We successfully induced TurboID expression in primary-cultured human BTICs from GBM patients, enabling the unbiased biotinylation of proteins in EVs. This method marks the first implementation of TurboID for unbiased global labeling of EV protein cargo in primary GBM cells. We identified unique miRNAs to be regulators of NPC’s transcriptome, and ontogenic analysis revealed upregulation of pathways involved in maintaining stem-like state, and upregulating PI3k-AKT, mTOR, and WNT signaling. This approach facilitates the investigation of EV-mediated communication and potential therapeutic targets, contributing to the understanding of GBM’s complex interactions with the brain’s microenvironment and the identification of biomarkers for improved diagnosis and treatment response.

ABSTRACT Glioblastoma (GBM), the most aggressive primary brain tumour in adults, presents significant challenges due to its universal recurrence and limited survival rates. A key driver of GBM progression is the subpopulation of brain tumour‐initiating cells (BTICs), which contribute to therapy resistance and interact with the tumour microenvironment, particularly the cellular components in the subventricular zone (SVZ). Extracellular vesicles (EVs) are critical mediators of intercellular communication, carrying bioactive molecules, such as proteins and RNAs, that can modulate the behaviour of recipient cells. This study investigates the role of EVs in GBM's communication with non‐cancer cells. We utilised the proximity‐labelling system TurboID to achieve global and unbiased labelling of proteins within GBM‐derived EVs. By inducing TurboID expression in primary‐cultured human BTICs from GBM patients, we achieved efficient biotinylation of EV proteins without compromising vesicle integrity, and performed proteomic analysis of biotinylated proteins, which revealed a diverse cargo within BTIC‐EVs. Our method marks the first implementation of TurboID for unbiased global labelling of EV protein cargo in primary cells. This approach facilitates the investigation of EV‐mediated communication and potential therapeutic targets, contributing to the understanding of GBM's complex interactions with the brain's microenvironment and identification of biomarkers for improved diagnosis and treatment response.

Abstract There is a general separation between medical and business education, despite the substantial intersection of these fields in hospital and industry settings. This separation hinders medical innovators, who rarely have opportunities to see how entrepreneurial concepts apply to the translation of medical innovation. To address this, the Office of Entrepreneurship at Mayo Clinic Florida provides experiential entrepreneurial training through an internal pitch competition: the alligator tank (AT). This study evaluates the impact and efficacy of the first seven years of the AT. Key metrics include a modified technology readiness level (TRL), determined by the presence of a disclosure, prototype, and preliminary data. A high TRL is not indicative of success in the pitch competition, leveling the playing field for early-stage inventions. The AT is characterized by broad representation across academic and professional ranks, departments, and genders, as well as strong participant retention. Innovators with prior disclosures are more likely to win the AT, presumably due to their experience. The AT serves as an institution-wide initiative that cultivates an inclusive, supportive innovation culture, fosters interdisciplinary medical innovation, and helps advance innovation maturity. Adopting the AT framework may help similar medical systems build an innovation ecosystem within their institutions.

Abstract Glioblastoma (GBM), the most aggressive primary brain tumor in adults, presents significant challenges due to its universal recurrence and limited survival rates, exacerbated when proximal to the lateral ventricles (LV). The subpopulation of brain tumor-initiating cells (BTICs) plays a pivotal role in tumor initiation and invasiveness, interacting with the microenvironment, particularly the cellular components in the subventricular zone (SVZ). Some mechanisms of intercellular communication present in the SVZ include paracrine, autocrine, direct cell contact, gap junctions, nanotubes, and more recently extracellular vesicles (EVs). EVs are membrane-bound particles released by cells that are central to intercellular communication. They have the ability to carry bioactive proteins, RNA, and other molecules that influence recipient cell behavior.This study investigates the role of EVs in GBM's communication with non-cancer cells. Our findings indicate that BTIC-derived EVs promote migration and proliferation (*p < 0.02, ****p <0.001) in neural progenitor cells (NPCs) in vitro, highlighting the EVs' role in altering the microenvironment. To identify the protein cargo contained in GBM-derived EVs, we utilized the innovative proximity-labeling system TurboID. We successfully induced TurboID expression in primary-cultured human BTICs from GBM patients, enabling the unbiased biotinylation of proteins in EVs. We isolated biotinylated proteins from BTIC lysates and BTIC-EVs, preserving the integrity of EVs, and conducted proteomic analysis via mass spectrometry. Our method marks the first implementation of TurboID for unbiased global labeling of EV protein cargo in primary GBM cells. This approach facilitates the investigation of EV-mediated communication and potential therapeutic targets, contributing to the understanding of GBM's complex interactions with the brain's microenvironment and the identification of biomarkers for improved diagnosis and treatment response. Citation Format: Marissa Russo, Emily Norton-Ramos, Maria Jose Ulloa Navas, Alfredo Quinones-Hinojosa, Hugo Guerrero-Cazares. Elucidating glioblastoma-derived extracellular vesicle cargo using TurboID: Implications for tumor microenvironment adaptation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 6579.

Abstract Glioblastoma (GBM) is the most common malignant primary brain tumor in adults with a median survival of 8-14 months and 5-year survival rate of 6.9%. Its aggressive nature arises mostly from molecular heterogeneity and resistance to standard of care (SOC), including radiation and temozolomide (TMZ). Recurrence is nearly inevitable, driven by highly invasive brain tumor initiating cells (BTICs). Our previous studies revealed that exposing BTICs to cerebrospinal fluid (CSF) from GBM patients increases cell migration and proliferation compared to non-cancer CSF. Transcriptomic analysis identified the upregulation of the SERPINA3 gene, which encodes alpha-1-antichymotrypsin (ACT). Silencing of SERPINA3 reduces BTIC migration and proliferation and abolishes the promigratory response to GBM-derived CSF, highlighting SERPINA3 as a potential therapeutic target. ACT has been reported to bind to DNA, although the implications of this interaction are unknown. We have previously observed higher levels of intranuclear ACT in human GBM compared to non-cancer brain tissues. We hypothesize that the nuclear localization of SERPINA3 in GBM contributes to increased malignancy, opening the possibility of therapeutically targeting its intranuclear transport. Here, we determined the intracellular localization of ACT in BTICs and GBM and compared it to non-cancer tissues. Additionally, we evaluated whether SOC affected intranuclear localization of ACT. Patient-derived BTICs were treated with TMZ, radiation, and a combination of both, to assess changes in ACT expression via Western Blot, PCR, and ICC. A decrease in cell confluency was correlated with a significant decrease (p<0.05) in SERPINA3 mRNA and overall protein expression when BTICs were treated with TMZ alone or in combination. Interestingly, confocal microscopy revealed a significant increase (p<0.05) in its nuclear localization, particularly with TMZ treatment, indicating a change in its intracellular distribution. Overall, nuclear translocation of SERPINA3 increases in response to SOC with potential implications as a treatment resistance mechanism.

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.

Abstract Glioblastoma (GBM) is the most common and lethal primary brain tumor in adults. Within the tumor, there is a subtype of cells deemed brain tumor initiating cells (BTICs), which contribute to tumor progression, therapy resistance, and tumoral heterogeneity. The tumor microenvironment, surrounding tumors, contains an ecosystem of cells in which BTICs can interact with and further promote tumor progression. In the lateral wall of the lateral ventricles, the neurogenic niche of the subventricular zone (SVZ), contains neural progenitor cells (NPCs) that self-renew and generate highly migratory neuroblasts. Interestingly, GBM tumors proximal to the SVZ are more proliferative, migratory, and negatively impact the survival of patients. We have previously observed that the presence of GBM induces reciprocal changes to the SVZ altering its neurogenic capacity and resulting in a more proliferative tumor. BTICs share similar self-renewal capacity to NPCs and may exert intercellular communication resulting in increased malignancy features. The mechanisms of intercellular communication, present in the SVZ include paracrine, autocrine, direct cell contact, gap junctions, nanotubes, and more recently extracellular vesicles (EVs). However, the exact mechanisms of how BTICs communicate with NPCs is not well understood. EVs are a heterogenous group of cell-derived membranous structures that serve as means of intercellular communication, allowing for cells to exchange proteins, lipids, RNA, and other genetic material. Cancer cells release higher amounts of EVs than non-malignant cells, and these EVs help communicate with other nearby cells, leading to promotion of tumorigenesis. We have observed that BTICs-derived EVs increase the proliferation of human NPCs, while altering their morphology and expression of stem cell markers. These effects are not observed when NPCs are treated with vesicle-free BTIC-derived secreted factors. To investigate the distinctions between BTIC secreted factors and protein cargo contained in BTIC-EVs, we employ the proximity protein labelling system, TurboID, and express this system in BTIC-EVs. The overarching goal of this project is to characterize BTIC-derived EV cargo to identify proteins that modify the GBM tumor microenvironment. We hypothesize that the phenotype of non-cancer NPCs is altered by distinct protein cargo contained in BTIC-derived EVs. The results of these experiments will help us to elucidate what BTIC-specific EV cargo impacts the tumor microenvironment, with the potential of revealing therapeutic targets for GBM. Citation Format: Marissa Russo, Maria Jose Ulloa Navas, Emily Norton-Ramos, Alfredo Quiñones Hinojosa, Hugo Guerrero Cazares. Exploring the differences between brain tumor initiating cell extracellular vesicles and secreted factors that influence the tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2776.

Abstract Glioblastoma (GBM) is the most malignant form of gliomas and is the most common and lethal primary brain tumor in adults. Within the tumor, there is a subtype of cells deemed brain tumor initiating cells (BTICs), which contribute to tumor progression, therapy resistance, and tumoral heterogeneity. The tumor microenvironment, surrounding tumors, contains an ecosystem of cells in which BTICs can interact with and further promote tumor progression. In the lateral wall of the lateral ventricles, the neurogenic niche of the subventricular zone (SVZ), contains neural stem cells (NSCs) that self-renew and generate highly migratory neural progenitor cells (NPCs). Interestingly, GBM tumors proximal to the SVZ are more proliferative, migratory, and negatively impact the survival of patients. We have previously observed that the presence of GBM induces reciprocal changes to the SVZ altering its neurogenic capacity and resulting in a more proliferative tumor. BTICs share the similar self-renewal capacity to NPCs and may exert intercellular communication resulting in increase malignancy features. However, the exact mechanisms of how GSCs communicate with NPCs is not well understood. Cancer cells release higher amounts of extracellular vesicles (EVs) than non-malignant cells. Cancer EVs help communicate with other nearby cells, leading to promotion of tumorigenesis. EVs are a heterogenous group of cell-derived membranous structures that serve as means of intercellular communication, allowing for cells to exchange proteins, lipids, RNA, and other genetic material. They can be further characterized into two main subtypes, small EVs, that range from 30-150nm, and large EVs, that range from 50-1000nm. EVs derived from gliomas or non-glioma cells in the tumor microenvironment are involved in tumor cell proliferation, invasion, malignancy, and drug resistance. The overarching goal of this project is to characterize BTIC-derived small EV cargo to identify proteins and RNAs that modify the GBM tumor microenvironment. We hypothesize that GBM-derived small extracellular vesicles alter the phenotype of non-cancer cells in the tumor microenvironment through distinct cargo contained in small extracellular vesicles. The results of these experiments will help us to elucidate what exact small EV cargo impacts the tumor microenvironment, with the potential of revealing possible therapeutic targets for GBM.The optimized protocol gives us the ability to enrich our desired EV population of small EVs from BTICs. BTIC-derived small EVs influence recipient NPCs by significantly upregulating markers for stemness, tumor aggressiveness, and invasion, as well as increasing NPC migration. Future experiments will include trying to establish a cell-specific labeling system in vitro to label EVs from BTICs, to allow for direct co-culture of BTICs with NPCs and other cells in the tumor microenvironment. Citation Format: Marissa Russo. The role of extracellular vesicles in the glioblastoma tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2370.

Abstract Glioblastoma (GBM) is the most common and aggressive primary neoplasm of the central nervous system. The location of GBM contributes significantly to patient outcomes, where tumors contacting the lateral ventricles (LVs) have increased expression of stem cell genes, increased incidence of distal recurrence, and decreased overall survival. While the reasons for these findings are not fully understood, we hypothesize they arise due to interactions with the subventricular zone (SVZ), the largest neurogenic niche in mammals. We examined bidirectional signals between GBM cells and neural progenitor cells (NPCs) in vitro and in vivo using a combination of patient-derived intraoperative samples, preclinical animal models, and the methionine tRNA synthetase L274G (MetRS*) nascent proteomic labeling system, which allows for cell-specific proteomics analysis from complex in vivo systems. In co-culture with NPCs, GBM cells increase their viability, proliferation, migration, and expression of malignancy-promoting proteins, including migratory proteins such as TAGLN, PALLD, and STAT1. In vivo, tumor proximity to the SVZ results in increased proliferation, increased expression of stemness markers, decreased survival, and altered tumor-specific proteome. We then examined the reciprocal effect of GBM cells on NPC biology. In vitro and in vivo, GBM cells decreased NPC proliferation and induced decreased neuronal maturation of NPCs. To determine NPC proteomic changes in vivo, we created a transgenic mouse line Nestin-CreERT2; STOPflox R26-MetRS L274G, where upon tamoxifen administration Nestin+ NPCs express GFP and MetRS*. Our results indicate that LV-proximal GBM induces decreased expression of neuronal maturation proteins such as Eml1, VGLUT1, and EAAT2, and an increase in pro-migratory factors such as Lamc1 in NPCs. In conclusion, there are bidirectional proteomic interactions between GBM cells and NPCs that contributes to altered neurogenesis and increased tumor malignancy of LV-proximal GBM. The signaling factors identified in our studies will result in identification of novel therapeutic targets for GBM.