Aggressive Glioblastoma Multiforme Research Articles

Stemness, invasion, and immunosuppression modulation in recurrent glioblastoma using nanotherapy.

The recurrent nature of glioblastoma negatively impacts conventional treatment strategies leading to a growing need for nanomedicine. Nanotherapeutics, an approach designed to deliver drugs to specific sites, is experiencing rapid growth and gaining immense popularity. Having potential in reaching the hard-to-reach disease sites, this field has the potential to show high efficacy in combatting glioblastoma progression. The presence of glioblastoma stem cells (GSCs) is a major factor behind the poor prognosis of glioblastoma multiforme (GBM). Stemness potential, heterogeneity, and self-renewal capacity, are some of the properties that make GSCs invade across the distant regions of the brain. Despite advances in medical technology and MRI-guided maximal surgical resection, not all GSCs residing in the brain can be removed, leading to recurrent disease. The aggressiveness of GBM is often correlated with immune suppression, where the T-cells are unable to infiltrate the cancer initiating GSCs. Standard of care therapies, including surgery and chemotherapy in combination with radiation therapy, have failed to tackle all the challenges of the GSCs, making it increasingly important for researchers to develop strategies to tackle their growth and proliferation and reduce the recurrence of GBM. Here, we will focus on the advancements in the field of nanomedicine that has the potential to show positive impact in managing glioblastoma tumor microenvironment. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Hyphenation of lipophilic ruthenium(II)-diphosphine core with 5-fluorouracil: an effective metallodrug against glioblastoma brain cancer cells.

Glioblastoma multiforme (GBM) is the most common highly aggressive malignant brain tumor, with a very limited chance for survival post-diagnosis and post-treatment. Despite significant advancement in GBM genomics implicated in molecularly targeted chemotherapies, the prognosis remains poor and requires new drug discovery approaches. We used fluoropyrimidine 5-fluorouracil (5-FU), an antimetabolite anticancer drug conjugated or 'caged' within a lipophilic Ru(II)-diphosphine (dppe) core formulated as [RuII(dppe)2(5-FU)]PF6 (Ru-DPPE-5FU), where dppe = 1,2-bis(diphenylphosphino)ethane, and evaluated its in vitro cytotoxicity in depth with aggressive GBM cells (LN229). The hydrophilic nature of 5-FU limits its passage through the blood-brain barrier (BBB), which prevents its effective accumulation and efficacy for GBM tumors. Herein, we attempted to modulate the lipophilicity of 5-FU by inserting it within a well-designed lipophilic {Ru(dppe)2}-core with anticipated higher efficiency towards GBM. The physicochemical properties of [RuII(dppe)2(5-FU)]PF6 (Ru-DPPE-5FU) were studied using various spectroscopic and analytical techniques. The molecular structure was determined using X-ray crystallography, showing a distorted {RuP4NO} octahedral geometry with bidentate (N, O) binding of 5-FU and its aromatization in the Ru(II)-bound form. The 31P-NMR spectra of Ru-DPPE-5FU showed four closely spaced distinct 31P-signals, indicating four unique chemical environments around P, and the strong coupling constants between them make it a second-order spectrum. The RuII/RuIII redox potential in Ru-DPPE-5FU shifted by ∼0.91 V towards the anodic region as compared to its precursor complex cis-[Ru(dppe)2Cl2] (Ru-DPPE-Cl). DFT-based theoretical calculations have been performed to correlate the experimental electronic absorption spectra and redox behaviours of the complexes. The electrostatic potential (ESP) plots indicate the delocalization of the charge density on the O-/F-atom from the 5-FU ligand towards Ru(II) upon its complexation. The antioxidant properties of all the compounds were quantified by a 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay. The hyphenation of the 5-fluorouracil (5-FU) ligand to the lipophilic {Ru(dppe)2}-core endowed lipophilicity to Ru-DPPE-5FU with higher in vitro cytotoxicity (IC50 = 2.37 μM) against the LN229 GBM cells as compared to the hydrophilic 5-FU, suggesting efficient cellular uptake. Further biological assays indicated that the complex is highly potent in inhibiting significant proliferation and spheroid formation and restricting the migratory potentials of the GBM cells. Increased caspase 3/7 activity and the presence of apoptotic bodies at the center of 3-D GBM spheroids as revealed by AO/EB dual staining indicated a deeper penetration of the lipophilic complex. The Ru-DPPE-5FU complex displayed lower cytotoxicity in HaCaT normal cells (IC50 = 7.27 μM) in comparison to LN229 cancer cells with a selectivity index (S.I.) of ≥3. Overall, the synergism and caging of 5-FU within the hydrophobic {Ru(dppe)2}-core improves the pharmacokinetic profile of Ru-DPPE-5FU as a potent anticancer agent for glioblastoma.

Abstract A034: Synthesis and biological activities of a novel series of “combi-molecules” designed to delay metabolic dealkylation prior to crossing the blood brain barrier in the context of optimizing their potency against glioblastoma multiforme

Abstract Introduction. Glioblastoma multiforme (GBM) is the most aggressive form of primary brain tumor in adults with a survival of only 12-15 months. GBM stem cells contribute to resistance to the DNA-damaging first-line chemotherapy, temozolomide, which accounts for tumor recurrence and treatment failure. Amplification of epidermal growth factor receptor (EGFR) is one of the most common genetic alterations associated with GBM aggressiveness. Despite the evidence that EGFR-induced pathway represents an attractive therapeutic target in GBM, gefitinib, an orally active selective EGFR-tyrosine kinase inhibitor, showed only a limited potency in clinical trials. We previously showed that ZR2002, an aminoquinazoline “combi-molecule” designed to possess mixed EGFR tyrosine kinase inhibition and DNA damaging properties, induced submicromolar cytotoxic activity against GBM stem cells resistant to temozolomide and gefitinib. Significantly increased survival of mice harboring an intracranially implanted aggressive temozolomide-resistant tumour by comparison with the clinical treatment gefitinib. Furthermore, mass spectrometry imaging provided evidence of its ability to cross the blood–brain barrier but metabolites devoid of its critical 2-chloroethyl DNA alkylating function were observed. Given that the loss of DNA alkylating species may decrease efficacy in vivo, here we show a structure-activity relationship study toward structures with increased stability to metabolic dealkylation. Materials and methods. Three glioblastoma cells line (U87-wt, U87-EGFR and U87-EGFRvIII) were used to determine IC50 of the new molecules with SRB assay. CD1 mice were treated with a dose of 100mg/kg by oral gavage and analyzed after 3h. Drug metabolism was measured by LC-MS. Results. In vitro growth inhibitory showed that the new analogues have the same cytotoxicity profile as ZR2002. In vivo analysis in mice administered p.o. with the new analogues showed that our newly synthesized molecules were less metabolized than ZR2002 using the ratio of intact structure levels/over metabolites as a parameter that we defined as extent of metabolism. Furthermore, they were found to maintain good brain penetration. Conclusions. These results proved that we were able to design and synthesize combi-molecules that can escape metabolism and preserve the 2-chloroethyl in vivo, a group that is required for the dual activity of the combi-molecules. Importantly, the combi-molecules, despite the structural change, remain very water soluble and available orally. Citation Format: Ana Belen Fraga-Timiraos, Caterina Facchin, Anne-Laure Larroque-Lombard, Bertrand Jacques Jean-Claude. Synthesis and biological activities of a novel series of “combi-molecules” designed to delay metabolic dealkylation prior to crossing the blood brain barrier in the context of optimizing their potency against glioblastoma multiforme [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr A034.

Mitochondrial glutamate transporter SLC25A22 uni-directionally export glutamate for metabolic rewiring in radioresistant glioblastoma

Glioblastoma Multiforme (GBM) is a malignant primary brain tumor. Radiotherapy, one of the standard treatments for GBM patients, could induce GBM radioresistance via rewiring cellular metabolism. However, the precise mechanism attributing to GBM radioresistance or targeting strategies to overcome GBM radioresistance are lacking. Here, we demonstrate that SLC25A22, a mitochondrial bi-directional glutamate transporter, is upregulated and showed uni-directionality from mitochondria to cytosol in radioresistant GBM cells, resulting in accumulating cytosolic glutamate. However, mitochondrial glutaminolysis-mediated TCA cycle metabolites and OCR are maintained constantly. The accumulated cytosolic glutamate enhances the glutathione (GSH) production and proline synthesis in radioresistant GBM cells. Increased GSH protects cells against ionizing radiation (IR)-induced reactive oxygen species (ROS) whereas increased proline, a rate-limiting substrate for collagen biosynthesis, induces extracellular matrix (ECM) remodeling, leading to GBM invasive phenotypes. Finally, we discover that genetic inhibition of SLC25A22 using miR-184 mimic decreases GBM radioresistance and aggressiveness both in vitro and in vivo. Collectively, our study suggests that SLC25A22 upregulation confers GBM radioresistance by rewiring glutamate metabolism, and SLC25A22 could be a significant therapeutic target to overcome GBM radioresistance.

Silencing GMPPB Inhibits the Proliferation and Invasion of GBM via Hippo/MMP3 Pathways.

Glioblastoma multiforme (GBM) is a highly aggressive malignancy and represents the most common brain tumor in adults. To better understand its biology for new and effective therapies, we examined the role of GDP-mannose pyrophosphorylase B (GMPPB), a key unit of the GDP-mannose pyrophosphorylase (GDP-MP) that catalyzes the formation of GDP-mannose. Impaired GMPPB function will reduce the amount of GDP-mannose available for O-mannosylation. Abnormal O-mannosylation of alpha dystroglycan (α-DG) has been reported to be involved in cancer metastasis and arenavirus entry. Here, we found that GMPPB is highly expressed in a panel of GBM cell lines and clinical samples and that expression of GMPPB is positively correlated with the WHO grade of gliomas. Additionally, expression of GMPPB was negatively correlated with the prognosis of GBM patients. We demonstrate that silencing GMPPB inhibits the proliferation, migration, and invasion of GBM cells both in vitro and in vivo and that overexpression of GMPPB exhibits the opposite effects. Consequently, targeting GMPPB in GBM cells results in impaired GBM tumor growth and invasion. Finally, we identify that the Hippo/MMP3 axis is essential for GMPPB-promoted GBM aggressiveness. These findings indicate that GMPPB represents a potential novel target for GBM treatment.

NQO1 drives glioblastoma cell aggressiveness through EMT induction via the PI3K/Akt/mTOR/Snail pathway.

Glioblastoma multiforme (GBM) is the most frequent and lethal cancer derived from the central nervous system, of which the mesenchymal (MES) subtype seriously influences the survival and prognosis of patients. NAD(P)H: quinone acceptor oxidoreductase 1 (NQO1) serves an important role in the carcinogenesis and progression of various types of cancer; however, the specific mechanism underlying the regulatory effects of NQO1 on GBM is unclear. Thus, the present study aimed to explore the role and mechanism of NQO1 in GBM progression. The results of bioinformatics analysis and immunohistochemistry showed that high expression of NQO1 was significantly related to the MES phenotype of GBM and shorter survival. In addition, MTT, colony formation, immunofluorescence and western blot analyses, and lung metastasis model experiments suggested that silencing NQO1 inhibited the proliferation and metastasis of GBM cells invitro and invivo. Furthermore, western blotting showed that the activity of the PI3K/Akt/mTOR signaling pathway was revealed to be inhibited by downregulation of NQO1 expression, whereas it was enhanced by overexpression of NQO1. Notably, co‑immunoprecipitation and ubiquitination experiments suggested that Snail was considered an important downstream target of NQO1 in GBM cells. Snail knockdown could eliminate the promoting effect of ectopic NQO1 on the proliferation and invasion of GBM cells, and reduce its effects on the activity of PI3K/Akt/mTOR signaling pathway. These results indicated that NQO1 could promote GBM aggressiveness by activating the PI3K/Akt/mTOR signaling pathway in a Snail‑dependent manner, and NQO1 and its relevant pathways may be considered novel targets for GBM therapy.

Rab32 promotes glioblastoma migration and invasion via regulation of ERK/Drp1-mediated mitochondrial fission

The highly widespread and infiltrative nature of glioblastoma multiforme (GBM) makes complete surgical resection hard, causing high recurrence rate and poor patients’ prognosis. However, the mechanism underlying GBM migration and invasion is still unclear. In this study, we investigated the role of a Ras-related protein Rab32 on GBM and uncovered its underlying molecular and subcellular mechanisms that contributed to GBM aggressiveness. The correlation of Rab32 expression with patient prognosis and tumor grade was investigated by public dataset analysis and clinical specimen validation. The effect of Rab32 on migration and invasion of GBM had been evaluated using wound healing assay, cell invasion assay, as well as protein analysis upon Rab32 manipulations. Mitochondrial dynamics of cells upon Rab32 alterations were detected by immunofluorescence staining and western blotting. Both the subcutaneous and intracranial xenograft tumor model were utilized to evaluate the effect of Rab32 on GBM in vivo. The expression level of Rab32 is significantly elevated in the GBM, especially in the most malignant mesenchymal subtype, and is positively correlated with tumor pathological grade and poor prognosis. Knockdown of Rab32 attenuated the capability of GBM’s migration and invasion. It also suppressed the expression levels of invasion-related proteins (MMP2 and MMP9) as well as mesenchymal transition markers (N-cadherin, vimentin). Interestingly, Rab32 transported Drp1 to mitochondrial from the cytoplasm and modulated mitochondrial fission in an ERK1/2 signaling-dependent manner. Furthermore, silencing of Rab32 in vivo suppressed tumor malignancy via ERK/Drp1 axis. Rab32 regulates ERK1/2/Drp1-dependent mitochondrial fission and causes mesenchymal transition, promoting migration and invasion of GBM. It serves as a novel therapeutic target for GBM, especially for the most malignant mesenchymal subtype.Schematic of Rab32 promotes GBM aggressiveness via regulation of ERK/Drp1-mediated mitochondrial fission. Rab32 transports Drp1 from the cytoplasm to the mitochondria and recruits ERK1/2 to activate the ser616 site of Drp1, which in turn mediates mitochondrial fission and promotes mesenchymal transition, migration and invasion of GBM.

Natural Products Targeting Hsp90 for a Concurrent Strategy in Glioblastoma and Neurodegeneration.

Glioblastoma multiforme (GBM) is one of the most common aggressive, resistant, and invasive primary brain tumors that share neurodegenerative actions, resembling many neurodegenerative diseases. Although multiple conventional approaches, including chemoradiation, are more frequent in GBM therapy, these approaches are ineffective in extending the mean survival rate and are associated with various side effects, including neurodegeneration. This review proposes an alternative strategy for managing GBM and neurodegeneration by targeting heat shock protein 90 (Hsp90). Hsp90 is a well-known molecular chaperone that plays essential roles in maintaining and stabilizing protein folding to degradation in protein homeostasis and modulates signaling in cancer and neurodegeneration by regulating many client protein substrates. The therapeutic benefits of Hsp90 inhibition are well-known for several malignancies, and recent evidence highlights that Hsp90 inhibitors potentially inhibit the aggressiveness of GBM, increasing the sensitivity of conventional treatment and providing neuroprotection in various neurodegenerative diseases. Herein, the overview of Hsp90 modulation in GBM and neurodegeneration progress has been discussed with a summary of recent outcomes on Hsp90 inhibition in various GBM models and neurodegeneration. Particular emphasis is also given to natural Hsp90 inhibitors that have been evidenced to show dual protection in both GBM and neurodegeneration.

Transcriptomic and connectomic correlates of differential spatial patterning among gliomas.

Unravelling the complex events driving grade-specific spatial distribution of brain tumour occurrence requires rich datasets from both healthy individuals and patients. Here, we combined open-access data from The Cancer Genome Atlas, the UK Biobank and the Allen Brain Human Atlas to disentangle how the different spatial occurrences of glioblastoma multiforme and low-grade gliomas are linked to brain network features and the normative transcriptional profiles of brain regions. From MRI of brain tumour patients, we first constructed a grade-related frequency map of the regional occurrence of low-grade gliomas and the more aggressive glioblastoma multiforme. Using associated mRNA transcription data, we derived a set of differential gene expressions from glioblastoma multiforme and low-grade gliomas tissues of the same patients. By combining the resulting values with normative gene expressions from post-mortem brain tissue, we constructed a grade-related expression map indicating which brain regions express genes dysregulated in aggressive gliomas. Additionally, we derived an expression map of genes previously associated with tumour subtypes in a genome-wide association study (tumour-related genes). There were significant associations between grade-related frequency, grade-related expression and tumour-related expression maps, as well as functional brain network features (specifically, nodal strength and participation coefficient) that are implicated in neurological and psychiatric disorders. These findings identify brain network dynamics and transcriptomic signatures as key factors in regional vulnerability for glioblastoma multiforme and low-grade glioma occurrence, placing primary brain tumours within a well established framework of neurological and psychiatric cortical alterations.

Locked and Loaded: β-Galactosidase Activated Photodynamic Therapy Agent Enables Selective Imaging and Targeted Treatment of Glioblastoma Multiforme Cancer Cells.

Selective detection and effective therapy of brain cancer, specifically, the very aggressive glioblastoma multiforme (GBM), remains one of the paramount challenges in clinical settings. While radiotherapy combined surgery is proposed as the main treatment course, it has several drawbacks such as complexity of the operation and common development of recurrent tumors in this course of patient care. Unique opportunities presented by photodynamic therapy (PDT) offer promising, effective, and precise therapy against GBM cells along with simultaneous imaging opportunities. However, activatable, theranostic molecular systems in PDT modality for GBM remained scarce. Specifically, even though elevated β-galactosidase (β-gal) activity in glioblastoma cells is well-documented, targeted, activatable therapeutic PDT agents have not been realized. Herein, we report a β-galactosidase (β-gal) activatable phototheranostic agent based on an iodinated resorufin core (RB-1) which was realized in only three steps with commercial reagents in 29% overall yield. RB-1 showed very high singlet oxygen (1O2) quantum yield (54%) accompanied by a remarkable turn-on response in fluorescence upon enzymatic activation. RB-1 was tested in different cell lines and revealed selective photocytotoxicity in U-87MG glioblastoma cells. Additionally, thanks to almost 7% fluorescence quantum yield (ΦF) despite extremely high 1O2 generation yield, RB-1 was also demonstrated as a successful agent for fluorescence imaging of U-87MG cells. Due to significantly lower (β-gal) activity in healthy cells (NIH/3T3), RB-1 stayed in a passive state and showed minimal photo and dark toxicity. RB-1 marks the first example of a β-gal activatable phototheranostic agent toward effective treatment of glioblastoma.

Sprouty 1 is associated with stemness and cancer progression in glioblastoma.

Glioblastoma multiforme (GBM) is the most severe type of human brain tumor, with a poor prognosis and a low survival rate. GBM is composed of a variety of cell types, including glioma stem-like cells (GSCs), which attribute to its therapeutic resistance (Boyd et al., 2020). Sprouty1 (SPRY1) was first identified as a receptor tyrosine kinases (RTK) signaling mediator in a mammalian cell (Christofori, 2003), however, its role in GBM is unknown. Therefore, the goal of this study was to investigate the role of SPRY1 in the stemness and aggressiveness of GSCs. The mRNA expression levels of SPRY1 were confirmed using quantitative reverse transcription PCR (RT-qPCR) in normal human astrocytes (NHA), glioma cells, and glioma stem cells. SPRY1 expression was inhibited in glioma stem cells using small interference RNA (siRNAs) to examine its role in cell proliferation and tumorsphere formation. Bioinformatics analyses were also employed to investigate the association of SPRY1 expression with patient survival, tumor grade, and subtypes publicly available datasets. We demonstrated that SPRY1 is highly expressed in glioma stem cells than in NHA, glioma cells, and differentiated glioma stem cells. siRNA-mediated downregulation of SPRY1 expression decreased the stemness and self-renewal ability in GSC11. Bioinformatics results showed that high SPRY1 expression correlates with poor overall survival in glioma patients. Our findings suggest that SPRY1 contributes to the stemness and aggressiveness of GBM.

Ribosomes and Ribosomal Proteins Promote Plasticity and Stemness Induction in Glioma Cells via Reprogramming.

Glioblastoma multiforme (GBM) is a lethal tumor that develops in the adult brain. Despite advances in therapeutic strategies related to surgical resection and chemo-radiotherapy, the overall survival of patients with GBM remains unsatisfactory. Genetic research on mutation, amplification, and deletion in GBM cells is important for understanding the biological aggressiveness, diagnosis, and prognosis of GBM. However, the efficacy of drugs targeting the genetic abnormalities in GBM cells is limited. Investigating special microenvironments that induce chemo-radioresistance in GBM cells is critical to improving the survival and quality of life of patients with GBM. GBM cells acquire and maintain stem-cell-like characteristics via their intrinsic potential and extrinsic factors from their special microenvironments. The acquisition of stem-cell-like phenotypes and aggressiveness may be referred to as a reprogramming of GBM cells. In addition to protein synthesis, deregulation of ribosome biogenesis is linked to several diseases including cancer. Ribosomal proteins possess both tumor-promotive and -suppressive functions as extra-ribosomal functions. Incorporation of ribosomes and overexpression of ribosomal protein S6 reprogram and induce stem-cell-like phenotypes in GBM cells. Herein, we review recent literature and our published data on the acquisition of aggressiveness by GBM and discuss therapeutic options through reprogramming.

Stanniocalcin 2 drives malignant transformation of human glioblastoma cells by targeting SNAI2 and Matrix Metalloproteinases

Glioblastoma multiforme (GBM) is the most malignant brain tumor and is refractory to conventional therapies. Although previous studies have proposed that the interaction between gene mutations and the external environment leads to the occurrence of GBM, the pathogenesis of GBM is still unclear and much remains to be studied. Herein, we show an association between human glycoprotein stanniocalcin-2 (STC2) and aggressive GBM progression, and demonstrate the underlying mechanism. Elevated STC2 expression and secretion greatly increase GBM cell growth and invasive phenotypes. Mechanistically, both, conditioned media (CM) containing STC2 and recombinant STC2, can induce the transformation of GBM cells into more malignant phenotypes by upregulating the expression of the epithelial-mesenchymal transition transcription factor, snail family transcription repressor 2 (SNAI2) as well as matrix metalloproteinases (MMPs). Moreover, we further demonstrate that the oncogenic function of STC2 in GBM is mediated through the MAPK signaling pathway. Collectively, these results identify the mechanism of STC2 targeting SNAI2 and MMPs through the MAPK pathway in GBM, and provide insights into a potential therapeutic strategy for GBM.

Ubiquitin-Specific Protease 6 n-Terminal-like Protein (USP6NL) and the Epidermal Growth Factor Receptor (EGFR) Signaling Axis Regulates Ubiquitin-Mediated DNA Repair and Temozolomide-Resistance in Glioblastoma.

Glioblastoma multiforme (GBM) is the most malignant glioma, with a 30–60% epidermal growth factor receptor (EGFR) mutation. This mutation is associated with unrestricted cell growth and increases the possibility of cancer invasion. Patients with EGFR-mutated GBM often develop resistance to the available treatment modalities and higher recurrence rates. The drug resistance observed is associated with multiple genetic or epigenetic factors. The ubiquitin-specific protease 6 N-terminal-like protein (USP6NL) is a GTPase-activating protein that functions as a deubiquitinating enzyme and regulates endocytosis and signal transduction. It is highly expressed in many cancer types and may promote the growth and proliferation of cancer cells. We hypothesized that USP6NL affects GBM chemoresistance and tumorigenesis, and that its inhibition may be a novel therapeutic strategy for GBM treatment. The USP6NL level, together with EGFR expression in human GBM tissue samples and cell lines associated with therapy resistance, tumor growth, and cancer invasion, were investigated. Its pivotal roles and potential mechanism in modulating tumor growth, and the key mechanism associated with therapy resistance of GBM cells, were studied, both in vitro and in vivo. Herein, we found that deubiquitinase USP6NL and growth factor receptor EGFR were strongly associated with the oncogenicity and resistance of GBM, both in vitro and in vivo, toward temozolomide, as evidenced by enhanced migration, invasion, and acquisition of a highly invasive and drug-resistant phenotype by the GBM cells. Furthermore, abrogation of USP6NL reversed the properties of GBM cells and resensitized them toward temozolomide by enhancing autophagy and reducing the DNA damage repair response. Our results provide novel insights into the probable mechanism through which USP6NL/EGFR signaling might suppress the anticancer therapeutic response, induce cancer invasiveness, and facilitate reduced sensitivity to temozolomide treatment in GBM in an autolysosome-dependent manner. Therefore, controlling the USP6NL may offer an alternative, but efficient, therapeutic strategy for targeting and eradicating otherwise resistant and recurrent phenotypes of aggressive GBM cells.

Abstract 6396: Detection of stemness and EMT in response to radiation in glioblastoma and ovarian cancer cells

Abstract Tumor recurrence and metastasis contribute to the poor prognosis of ovarian cancer (OC) and glioblastoma multiforme (GBM). The aggressiveness of GBM and OC during recurrence creates a need to identify potential therapeutic targets. The cancer stem cell (CSC)-like phenotype and epithelial mesenchymal transition (EMT) have been shown to contribute to cancer aggressiveness, which makes CSCs and EMT viable targets for therapeutic intervention. EMT is a normal process during development and wound healing, but its reactivation in cancer cells contributes to metastasis. To detect CSC phenotypes in live cells without the use of antibodies, we are analyzing core stem cell transcription factors in which a SOX2/OCT4 response element, designated as SORE6, regulates a GFP reporter system. Also, to detect EMT we are using a GFP based reporter regulated by Zeb1 3’ UTR, a common EMT marker. Our aim is to detect changes in stemness and EMT in response to proton and photon ionizing radiation (IR). We hypothesize that proton and photon IR have similar effects on aggressiveness in OC and GBM. To investigate this, 2 GBM cancer cell lines, 1 breast cancer cell line, 1 OC cell line, and two patient derived samples were exposed to 0, 1, 2, 4 and 8Gy of 250 MeV proton and 6 MeV photon beams. 72 hours post IR exposure, flow cytometry analysis quantified reporter activity. We found an increase in stemness as radiation dosage increased in most cell lines. Results suggest that proton radiation increases stemness more than photon exposure. Citation Format: Aaron Keniston, Alondra Enciso, Yeonkyu Jung, Ashley Antonissen, Ryan Fuller, Ann Morcos, Antonella Bertucci, Marcello Vazquez, Juli Unternaehrer. Detection of stemness and EMT in response to radiation in glioblastoma and ovarian cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6396.

Novel cancer stem cell marker MVP enhances temozolomide-resistance in glioblastoma

The resistance of highly aggressive glioblastoma multiforme (GBM) to chemotherapy is a major clinical problem resulting in a poor prognosis. GBM contains a rare population of self-renewing cancer stem cells (CSCs) that proliferate, spurring the growth of new tumors, and evade chemotherapy. In cancer, major vault protein (MVP) is thought to contribute to drug resistance. However, the role of MVP as CSCs marker remains unknown and whether MVP could sensitize GBM cells to Temozolomide (TMZ) also is unclear. We found that sensitivity to TMZ was suppressed by significantly increasing the MVP expression in GBM cells with TMZ resistance. Also, MVP was associated with the expression of other multidrug-resistant proteins in tumorsphere of TMZ-resistant GBM cell, and was highly co-expressed with CSC markers in tumorsphere culture. On the other hands, knockdown of MVP resulted in reduced sphere formation and invasive capacity. Moreover, high expression of MVP was associated with tumor malignancy and survival rate in glioblastoma patients. Our study describes that MVP is a potentially novel maker for glioblastoma stem cells and may be useful as a target for preventing TMZ resistance in GBM patients.

Role of Lamin A/C as Candidate Biomarker of Aggressiveness and Tumorigenicity in Glioblastoma Multiforme

Nuclear lamina components have long been regarded as scaffolding proteins, forming a dense fibrillar structure necessary for the maintenance of the nucleus shape in all the animal kingdom. More recently, mutations, aberrant localisation and deregulation of these proteins have been linked to several diseases, including cancer. Using publicly available data we found that the increased expression levels of the nuclear protein Lamin A/C correlate with a reduced overall survival in The Cancer Genome Atlas Research Network (TCGA) patients affected by glioblastoma multiforme (GBM). We show that the expression of the LMNA gene is linked to the enrichment of cancer-related pathways, particularly pathways related to cell adhesion and cell migration. Mimicking the modulation of LMNA in a GBM preclinical cancer model, we confirmed both in vitro and in vivo that the increased expression of LMNA is associated with an increased aggressiveness and tumorigenicity. In addition, delving into the possible mechanism behind LMNA-induced GBM aggressiveness and tumorigenicity, we found that the mTORC2 component, Rictor, plays a central role in mediating these effects.

BMP4 to increase connexin43 expression and interaction with β-catenin in glioblastoma stem cells.

e14045 Background: Glioblastoma multiforme (GBM) is the most commonly occurring and most lethal primary central nervous system tumor. Treatment for GBM involves an aggressive combination of surgical resection, radiotherapy, and temozolomide chemotherapy. While intensive therapy has shown marginal improvement in prognosis, the median survival for GBM patients remains between twelve to fourteen months. The aggressiveness of GBM is attributed to the cellular heterogeneity and the invasive nature of the tumor, as well as the presence of glioblastoma cancer stem cells (GSCs). GSCs are a subpopulation of slowly dividing cells within GBM tumors that can survive chemotherapy and irradiation treatments targeting proliferating cells. The remaining quiescent GSCs can then enter an active state of self-renewal and differentiation through asymmetric division that contributes to tumor recurrence by recapitulating the heterogeneous tumor in relatively short order. Previously, we have identified a non-junctional, tumorigenic function for the gap junction protein connexin43 (Cx43) through its interaction with microtubules in GSCs. However, when GSCs are differentiated, this interaction decreases while Cx43 expression increases, suggesting an alternate function for Cx43. Bone Morphogenic Proteins (BMPs) have been implicated in GSC differentiation and their role in human tumorigenesis has remained largely unknown in GSCs. In this study, we aim to determine the effect of BMP on Cx43 expression and localization in GSCs. Methods: In this study, we used GBM patient-derived GSCs isolated from two GBM tumors following resection at Carilion Clinic, and maintained in stem cell medium. The effect of BMP4 signaling on Cx43 expression and localization in GSCs was determined using RT-qPCR, immunofluorescence, western blot, and co-immunoprecipitation. Results: Preliminary data show that BMP4 treatment increases Cx43 expression at the protein and mRNA levels through nuclear translocation and transcriptional activity of β-catenin. In addition, BMP4 treatment increases the interaction between Cx43 and β-catenin at the plasma membrane. Further studies are underway to determine the implications of disrupting Cx43/β-catenin interaction in GSC differentiation. Conclusions: While additional experiments are needed, our findings may be adapted as a prognostic indicator to determine patients’ susceptibility to traditional GBM therapies, and aid in novel therapeutic development to eradicate GSCs in GBM and prevent tumor recurrence following treatment.

A short review on cross-link between pyruvate kinase (PKM2) and Glioblastoma Multiforme.

Pyruvate kinase (PK) catalyzes the last irreversible reaction of glycolysis pathway, generating pyruvate and ATP, from Phosphoenol Pyruvate (PEP) and ADP precursors. In mammals, four different tissue-specific isoforms (M1, M2, L and R) of PK exist, which are translated from two genes (PKL and PKR). PKM2 is the highly expressed isoform of PK in cancers, which regulates the aerobic glycolysis via reprogramming cancer cell's metabolic pathwaysto provide an anabolicadvantage to the tumor cells. In addition to the established role of PKM2 in aerobic glycolysis of multiple cancer types, various recent findings have highlighted the non-metabolic functions of PKM2 in brain tumor development. Nuclear PKM2 acts as a co-activator and directly regulates gene transcription. PKM2 dependent transactivation of various oncogenic genes is instrumental in the progression and aggressiveness of Glioblastoma Multiforme (GBM). Also, PKM2 acts as a protein kinase in histone modification which regulates gene expression and tumorigenesis. Ongoing research has explored novel regulatory mechanisms of PKM2 and its association in GBM progression. This review enlists and summarizes the metabolic and non-metabolic roles of PKM2 at the cellular level, and its regulatory function highlights the importance of the nuclear functions of PKM2 in GBM progression, and an emerging role of PKM2 as novel cancer therapeutics.

Role of Purinome, A Complex Signaling System, In Glioblastoma Aggressiveness.

Many recent papers dealing with glioblastoma multiforme (GBM), the most common/lethal human brain tumor, are aimed at identifying new druggable targets, hopefully useful for more effective therapies than the current ones. In this context, the purinergic system, present in all living cells, is arousing considerable interest, mainly in relation to adenine-based compounds. It is composed of: intracellular purine nucleotides, nucleosides and nucleobases involved in fundamental biological processes such as cell duplication, chemical energy supply, intracellular signaling, and protein metabolism regulation (Frenguelli and Dale, 2020); extracellular purines (the same found intracellularly), among which adenine-based nucleotides/nucleosides behave as signal molecules interacting with specific receptors, namely P1 and P2 for adenosine (ADO) and ATP/ADP, respectively (Burnstock, 2018); a wide array of intra/extracellular metabolizing enzymes (Yegutkin, 2014); transporters, mostly deputed to regain nucleosides/bases to restore the intracellular purine pool (Choi and Berdis, 2012). The advent of the “omic” era has induced scientists to indicate this complex network as “purinome”, to emphasize that its components act in close/interactive fashion. This concerted activity maintains cells in homeostatic/physiological conditions, while purinome imbalance causes/is implicated in profound alterations of normal cell biological activities, thus contributing to malignant cell transformation toward more aggressive phenotypes, as shown in different tumors (Boison and Yegutkin, 2019; Campos-Contreras et al., 2020), including GBM (Giuliani et al., 2018; Zhou et al., 2020). Here, we exemplified some emerging alterations of purinome, highlighting how they influence GBM progression, in order to outline a picture, which can be the natural premise for suggesting new checkpoints of GBM aggressiveness.