U87 Glioma Cells Research Articles

Abstract 7110: Characterizing pY240-PTEN:Ki-67 interactions and development of a PPI disrupting peptide

Abstract Glioblastoma (GBM) is the most aggressive and common malignant primary brain tumor. Standard of care for GBM patients involves chemotherapy and ionizing radiation which induce DNA damage to kill tumor cells; however resistance to these treatment modalities commonly develop through various mechanisms. One novel mechanism of radioresistance is through enhanced homologous recombination (HR) DNA damage response (DDR) mediated by nuclear-localized tyrosine-phosphorylated PTEN (pY240-PTEN) recruited to chromatin through interaction with the PP1 Binding Domain (PP1BD) of Ki-67. PTEN is known to play an important tumor-suppressive role and is found to be mutated in approximately 40% of GBMs. A Y240F-PTEN knock-in mouse model has shown that loss of Y240 phosphorylation results in IR sensitivity. Ki-67 dependent, pY240-PTEN facilitated DDR may be regulated by currently uncharacterized interactions within the Ki-67 PP1BD and determination of these interactions may enable development of complex-disrupting peptides capable of radiosensitizing glioma cells. To this end, I have identified residues in the Ki-67 PP1BD that are essential for pY240-PTEN interaction via streptavidin pulldown of N-terminal biotinylated peptides synthesized with alanine mutations at all residues spanning the Ki-67 PP1BD. Orthogonally, glioma cell lines have been engineered that stably express Ki-67 minigene constructs harboring mutation of the identified PP1BD residues. The effects of these mutations on PTEN:Ki-67 interaction, as well as DDR, HR, chromatin accessibility, and colony formation efficiency are currently being interrogated. Competitor peptides have been designed based on candidate Ki-67 residues and evaluated for their ability to bind PTEN. Further optimization of these peptides has led to candidates that are being assessed for stability and potential to radiosensitize glioma cells. In addition, regulation of pY240-PTEN:Ki-67 interaction by posttranslational modification of the Ki-67 PP1BD by aurora B kinase and cyclin dependent kinase 1 has been investigated through pulldown of biotinylated peptides harboring phosphorylated candidate residues. Lastly, Ki-67 has been knocked out in U87 glioma cells, as well as TS528 glioma stem like cells, and the resulting effect on IR sensitivity and DDR is being investigated in the absence, or presence of PTEN. Overall, this project has begun to characterize the regulation and critical molecular interactions between pY240-PTEN and Ki-67, elucidating potential strategies that could disrupt these interactions to enhance the efficacy of radiotherapy. Citation Format: Brandon Jones, Sejal Patel, Frank Furnari. Characterizing pY240-PTEN:Ki-67 interactions and development of a PPI disrupting peptide [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 7110.

Abstract 701: Preclinical data of a novel DNA-PK inhibitor in combination with radiation therapy shows promise in the treatment of established GBM and lung carcinoma cell lines

Abstract Radiation therapy (RT) is a cornerstone of oncologic therapy for the majority of solid malignancies, and unrepaired DNA double-strand breaks are responsible for radiation-induced cytotoxicity. RT-induced DNA lesions can be repaired by multiple mechanisms including homologous recombination (HR) and non-homologous end joining (NHEJ), and disruption of either of these pathways can enhance cytotoxicity. A key component of the NHEJ pathway is the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs), and loss of kinase activity can significantly increase radiosensitivity. Herein we describe the results of our medicinal chemistry campaign to develop a potent and selective DNA-PKcs inhibitor, WNC0901. WNC0901 inhibits DNA-PKcs kinase activity in a cell free system with an IC50 of 0.071 nM and demonstrated at least 30-fold higher sensitivity than other family members (ATM, ATR, mTOR, PI3K). WNC0901 has limited aldehyde oxidase (AO) liability with a T1/2 >2000 min in liver cytosol and is stable for over 120 minutes in the presence and absence of an AO inhibitor. A preliminary pharmacokinetic analysis in wista han rat (IV=2mg/kg, PO=20mg/kg) demonstrated 116% apparent absolute oral bioavailability, 2.6 hour terminal half-life, 33.0 mL/min/kg clearance, and a 2.6% unbound brain-to-plasma partition coefficient (Kpuu). WNC0901 also had favorable pharmacokinetic properties in beagle dog (IV=2mg/kg, PO=20mg/kg) with moderate clearance (8.5 mL/min/kg), high apparent absolute oral bioavailability (131%) with good exposure (AUC=36092 h*ng/mL), moderate half-life (4.28 h), and low protein binding (74.3% fraction unbound). The volume of distribution was moderate in both species (Vss = 1.32 L/kg in wistar han rat and 1.87 L/kg in beagle dog). In cell culture, WNC0901 inhibited autophosphorylation of DNA-PKcs in HT29 cells irradiated with 10 Gy with an IC50 of 32.7 nM and robustly inhibited autophosphorylation in both U251 glioma and A549 lung cancer cell lines at 300 nM in combination with 5Gy. In a clonogenic assay, 5Gy irradiation (10% survival) combined with 100nM WNC0901 demonstrated modestly enhanced cell killing (1.5% survival), and maximal effects were seen at 300nM (0.04% survival, p<0.01). Similar radiosensitizing effects with 300 nM WNC0901 were seen in the A549 cell line (0.2% survival with combination compared to 19% with 5Gy alone, p<0.01). In summary, WNC0901 inhibits DNA-PK kinase activity and provides potent radiosensitization in a GBM and lung cancer cell line. Future studies will assess the combination of WNC0901 and RT in GBM patient-derived xenograft models in vivo. Citation Format: Ann C. Mladek, Danielle L. Burgenske, William F. Elmquist, Wei Zhong, Jann N. Sarkaria. Preclinical data of a novel DNA-PK inhibitor in combination with radiation therapy shows promise in the treatment of established GBM and lung carcinoma cell lines [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 701.

D-2-HG Inhibits IDH1mut Glioma Growth via FTO Inhibition and Resultant m6A Hypermethylation.

IDH1mut gliomas produce high levels of D-2-HG, an oncometabolite capable of inhibiting α-ketoglutarate-dependent dioxygenases critical to a range of cellular functions involved in gliomagenesis. IDH1mut gliomas also exhibit slower growth rates and improved treatment sensitivity compared to their IDH1wt counterparts. This study explores the mechanism driving apparent reduced growth in IDH1mut gliomas. Specifically, we investigated the relationship between IDH1mut and the RNA m6A demethylases FTO and ALKBH5, and their potential for therapeutic targeting. We investigated the role of D-2-HG and m6A in tumor proliferation/viability using glioma patient tumor samples, patient-derived gliomaspheres, and U87 cells, as well as with mouse intracranial IDH1wt gliomasphere xenografts. MeRIP-Seq RNA sequencing was used to identify m6A enriched transcripts in IDH1mut glioma. We show that IDH1mut production of D-2-HG is capable of reducing glioma cell growth via inhibition of the m6A epitranscriptomic regulator, FTO, with resultant m6A hypermethylation of a set of mRNA transcripts. Based on unbiased MeRIP-Seq epitranscriptomic profiling, we identify ATF5 as a hypermethylated, downregulated transcript that potentially contributes to increased apoptosis. We further demonstrate how targeting this pathway genetically and pharmacologically reduces the proliferative potential of malignant IDH1wt gliomas, both in vitro and in vivo. Our work provides evidence that selective inhibition of the m6A epitranscriptomic regulator FTO attenuates growth in IDH1wt glioma, recapitulating the clinically favorable growth phenotype seen in the IDH1mut subtype.

MiR-26-3p regulates proliferation, migration, invasion and apoptosis of glioma cells by targeting CREB1

To investigate the regulatory role of miR-26b-3p in proliferation, migration and invasion of glioma. The expressions of miR-26b-3p and cAMP-responsive element binding protein 1 (CREB1) in gliomas of different pathological grades were detected with RT-qPCR and Western blotting. Bioinformatic methods were used to analyze the target sequence of miRNA-26b-3p binding to CREB1, and dual luciferase gene reporter experiment was performed to explore the mechanism for targeted regulation of CREB1 by miR-26b-3p. Glioma U251 cells were treated with miR-26b-3p mimic or inhibitor, and the changes in CREB1 expression and cell proliferation, migration, invasion and apoptosis were determined with Western blotting, CCK-8 assay, wound healing assay, Transwell assay, and flow cytometry. The expression of miR-26b-3p decreased while CREB1 expression increased significantly as the pathological grade of gliomas increased (P < 0.05). Dual luciferase gene reporter experiment confirmed that CREB1 was a downstream target of miR-26b-3p. Inhibition of miR-26b-3p significantly upregulated the expression of CERB1, suppressed apoptosis and promoted proliferation and invasion of glioma cells, and overexpression of miR-26b-3p produced the opposite effects (P < 0.05). MiR-26b-3p regulates CREB1 expression to modulate apoptosis, proliferation, migration and invasion of glioma cells, thereby participating in tumorigenesis and progression of glioma.

Calycosin (CA) inhibits proliferation, migration and invasion by suppression of CXCL10 signaling pathway in glioma.

Glioblastoma is the most common malignant tumor in the central nervous system and its occurrence and development is involved in various molecular abnormalities. C-X-C chemokine ligand 10 (CXCL10), an inflammatory chemokine, has been reported to be related to the pathogenesis of cancer while it has not yet been linked to glioma. Calycosin, a bioactive compound derived from Radix astragali, has demonstrated anticancer properties in several malignancies, including glioma. Nonetheless, its underlying mechanisms are not fully understood. This study explores CXCL10 as a potential therapeutic target for calycosin in the suppression of glioblastoma. We observed that CXCL10 expression correlates positively with glioma malignancy and inversely with patient prognosis, highlighting its potential as a glioblastoma treatment target. Furthermore, we found that calycosin inhibited proliferation, migration, and invasion in U87 and U251 glioma cells, and decreased CXCL10 expression in a dose-dependent manner, along with its downstream effectors such as NLRP3, NF-κB, and IL-1β. Additionally, molecular docking experiments demonstrated that calycosin exhibits a notable binding affinity to CXCL10. Overexpression of CXCL10 counteracted the inhibitory effects of calycosin on cell proliferation, migration, and invasion, while CXCL10 knockdown enhanced these effects. Finally, we verified that calycosin inhibited glioma growth in a xenograft mouse model and downregulated CXCL10 and its downstream molecules. These findings suggest that targeting CXCL10 may be an effective strategy in glioblastoma treatment, and calycosin emerges as a potential therapeutic agent.

EZH2-regulated PARP-1 Expression is a Likely Mechanism for the Chemoresistance of Gliomas to Temozolomide.

Chemoresistance in gliomas accounts for the major cause of tumor progress and recurrence during comprehensive treatment with alkylating agents including temozolomide (TMZ). The oncogenic role of Enhancer of zeste homolog 2 (EZH2) has been identified in many solid malignancies including gliomas, though the accurate effect of EZH2 on chemotherapy resistance of gliomas has been elusive. To elucidate the role of EHZ2 on TMZ resistance of gliomas and the molecular mechanisms. Immunohistochemistry (IHC) and Reverse transcription-quantitative (RT-q) PCR, and western blot assay were performed for expressional analysis. Cell Counting Kit-8 (CCK-8) assay was applied to determine the TMZ sensitivity. EZH2-silencing lentivirus was generated for mechanic study. EZH2 was overexpressed in gliomas both at the transcriptional and protein levels. EZH2 level in glioma cell lines was positively correlated with resistance to TMZ, represented by the 50% inhibition rate (IC50). Moreover, there was increased TMZ sensitivity in EZH2-inhibited glioma cells than in the control cells. Furthermore, we determined that PARP1 was a common molecule among the downregulated DNA repair proteins in both U251 and U87 glioma cell lines after EZH2 inhibition. Specifically, we observed a spontaneous increase of PARP1 expression with TMZ treatment and interestingly, the increase of PARP1 could be also reduced by EZH2 inhibition in the glioma cells. Finally, combined treatment with lentivirus-induced EZH2 inhibition and a PARP1 inhibitor dramatically enhanced TMZ cytotoxicity compared with either one alone. EZH2-PARP-1 signaling axis is possibly responsible for the chemoresistance of gliomas to TMZ. Simultaneously inhibiting these two genes may improve the outcome of TMZ chemotherapy.

Methylseleninic acid inhibits human glioma growth in vitro and in vivo by triggering ROS-dependent oxidative damage and apoptosis.

Selenium-containing agents showed novel anticancer activity by triggering pro-oxidative mechanism. Studies confirmed that methylseleninic acid (MeSe) displayed broad-spectrum anti-tumor activity against kinds of human cancers. However, the anticancer effects and mechanism of MeSe against human glioma growth have not been explored yet. Herein, the present study showed that MeSeA dose-dependently inhibited U251 and U87 human glioma cells growth in vitro. Flow cytometry analysis indicated that MeSe induced significant U251 cells apoptosis with a dose-dependent manner, followed by the activation of caspase-7, caspase-9 and caspase-3. Immunofluorescence staining revealed that MeSe time-dependently caused reactive oxide species (ROS) accumulation and subsequently resulted in oxidative damage, as convinced by the increased phosphorylation level of Ser428-ATR, Ser1981-ATM, Ser15-p53 and Ser139-histone. ROS inhibition by glutathione (GSH) effectively attenuated MeSe-induced ROS generation, oxidative damage, caspase-3 activation and cytotoxicity, indicating that ROS was an upstream factor involved in MeSe-mediated anticancer mechanism in glioma. Importantly, MeSe administration in nude mice significantly inhibited glioma growth in vivo by inducing apoptosis through triggering oxidative damage. Taken together, our findings validated the possibility that MeSe as a selenium-containing can act as potential tumor chemotherapy agent for therapy of human glioma.

Predictive potentials of glycosylation-related genes in glioma prognosis and their correlation with immune infiltration

Glycosylation is currently considered to be an important hallmark of cancer. However, the characterization of glycosylation-related gene sets has not been comprehensively analyzed in glioma, and the relationship between glycosylation-related genes and glioma prognosis has not been elucidated. Here, we firstly found that the glycosylation-related differentially expressed genes in glioma patients were engaged in biological functions related to glioma progression revealed by enrichment analysis. Then seven glycosylation genes (BGN, C1GALT1C1L, GALNT13, SDC1, SERPINA1, SPTBN5 and TUBA1C) associated with glioma prognosis were screened out by consensus clustering, principal component analysis, Lasso regression, and univariate and multivariate Cox regression analysis using the TCGA-GTEx database. A glycosylation-related prognostic signature was developed and validated using CGGA database data with significantly accurate prediction on glioma prognosis, which showed better capacity to predict the prognosis of glioma patients than clinicopathological factors do. GSEA enrichment analysis based on the risk score further revealed that patients in the high-risk group were involved in immune-related pathways such as cytokine signaling, inflammatory responses, and immune regulation, as well as glycan synthesis and metabolic function. Immuno-correlation analysis revealed that a variety of immune cell infiltrations, such as Macrophage, activated dendritic cell, Regulatory T cell (Treg), and Natural killer cell, were increased in the high-risk group. Moreover, functional experiments were performed to evaluate the roles of risk genes in the cell viability and cell number of glioma U87 and U251 cells, which demonstrated that silencing BGN, SDC1, SERPINA1, TUBA1C, C1GALT1C1L and SPTBN5 could inhibit the growth and viability of glioma cells. These findings strengthened the prognostic potentials of our predictive signature in glioma. In conclusion, this prognostic model composed of 7 glycosylation-related genes distinguishes well the high-risk glioma patients, which might potentially serve as caner biomarkers for disease diagnosis and treatment.

Melitoxin Inhibits Proliferation, Metastasis, and Invasion of Glioma U251 Cells by Down-regulating F2RL1.

As the principal active component of bee venom, melittin has an anti-cancer effect in different cancers. This study was aimed to investigate the effect of melittin in glioma and explore whether F2RL1 is closely involved in glioblastoma cells proliferation. TCGA and GES databases were used to evaluate the role of F2RL1 in gliomas. The U251 cells were divided into a control lentivirus + PBS group (NC-PBS), F2RL1 intervention lentivirus + PBS group (KD-PBS), control lentivirus + melittin group (NC-melittin), and F2RL1 intervention lentivirus + melittin group (KD-melittin). Cell proliferation was detected by MTT and EDU staining assays. The apoptosis rate was assessed by flow cytometry. Expressions of genes related to apoptosis, cycle arrest, migration, and invasion were detected by qRT-PCR. Cellular LDH concentrations were detected by ELISA. The subcutaneous tumor volume of nude mice was analyzed by xenograft method. F2RL1 was significantly overexpressed in glioma tissues and were reduced in the melittin-treated group compared to the blank group. F2RL1 knockdown and melittin alone or in combination increased the proportion of cells in the G1-phase, and the combination was more pronounced. The KD-melittin group showed a decrease in the number of viable cells at 24, 48, 72, and 96 h compared to the NC-PBS group. The number of cell migration and invasion was decreased in the KD-melittin group compared to the other groups. Moreover, the genes related to cell cycle arrest and apoptosis were significantly changed in the KD-melittin group. At weeks 4, 5, and 6, the tumor volume in the KD-melittin group was smaller than that in the KD-PBS group and NC-melittin group. Interference with the target gene F2RL1 inhibited the proliferation of glioma U251 cells, and melittin treatment inhibited the proliferation of glioma U251 cells. Melittin inhibited the proliferation of glioma U251 cells by suppressing the expression of target gene F2RL1.

CLEC19A overexpression inhibits tumor cell proliferation/migration and promotes apoptosis concomitant suppression of PI3K/AKT/NF-κB signaling pathway in glioblastoma multiforme.

GBM is the most frequent malignant primary brain tumor in humans. The CLEC19A is a member of the C-type lectin family, which has a high expression in brain tissue. Herein, we sought to carry out an in-depth analysis to pinpoint the role of CLEC19A expression in GBM. To determine the localization of CLEC19A, this protein was detected using Western blot, Immunocytochemistry/Immunofluorescence, and confocal microscopy imaging. CLEC19A expression in glioma cells and tissues was evaluated by qRT-PCR. Cell viability, proliferation, migration, and apoptosis were examined through MTT assay, CFSE assay, colony formation, wound healing assay, transwell test, and flow cytometry respectively after CLEC19A overexpression. The effect of CLEC19A overexpression on the PI3K/AKT/NF-κB signaling pathway was investigated using Western blot. An in vivo experiment substantiated the in vitro results using the glioblastoma rat models. Our in-silico analysis using TCGA data and measuring CLEC19A expression level by qRT-PCR determined significantly lower expression of CLEC19A in human glioma tissues compared to healthy brain tissues. By employment of ICC/IF, confocal microscopy imaging, and Western blot we could show that CLEC19A is plausibly a secreted protein. Results obtained from several in vitro readouts showed that CLEC19A overexpression in U87 and C6 glioma cell lines is associated with the inhibition of cell proliferation, viability, and migration. Further, qRT-PCR and Western blot analysis showed CLEC19A overexpression could reduce the expression levels of PI3K, VEGFα, MMP2, and NF-κB and increase PTEN, TIMP3, RECK, and PDCD4 expression levels in glioma cell lines. Furthermore, flow cytometry results revealed that CLEC19A overexpression was associated with significant cell cycle arrest and promotion of apoptosis in glioma cell lines. Interestingly, using a glioma rat model we could substantiate that CLEC19A overexpression suppresses glioma tumor growth. To our knowledge, this is the first report providing in-silico, molecular, cellular, and in vivo evidences on the role of CLEC19A as a putative tumor suppressor gene in GBM. These results enhance our understanding of the role of CLEC19A in glioma and warrant further exploration of CLEC19A as a potential therapeutic target for GBM.

Synthesis of carbon dot based Schiff bases and selective anticancer activity in glioma cells.

Schiff bases have remarkable anticancer activity and are used for glioma therapy. However, the poor water solubility/dispersibility limits their therapeutic potential in biological systems. To address this issue, carbon dots (CDs) have been utilized to enhance the dispersibility in water and biological efficacy of Schiff bases. The amino groups on the surface of CDs were conjugated effectively with the aldehyde group of terephthalaldehyde to form novel CD-based Schiff bases (CDSBs). The results of the MTT assays demonstrate that CDSBs have significant anticancer activity in glioma GL261 cells and U251 cells, with IC50 values of 17.9 μg mL-1 and 14.9 μg mL-1, respectively. CDSBs have also been found to have good biocompatibility with normal glial cells. The production of reactive oxygen species (ROS) in GL261 glioma cells showed that CDSBs, at a concentration of 44 μg mL-1, resulted in approximately 13 times higher intracellular ROS production than in the control group. These experiments offer evidence that CDSBs induce mitochondrial damage, leading to a reduction in mitochondrial membrane potential in GL261 cells. In particular, in this work, CDs serve not as carriers, but as an integral part of the anticancer drugs, which can expand the role of CDs in cancer treatment.

CDC6 overexpression contributes to the malignant phenotype of glioma via IL6/JAK2/STAT3 signaling.

Glioma, a prevalent primary tumor of the central nervous system, is targeted by molecular therapies aiming to intervene in specific genes and signaling pathways to inhibit tumor growth and spread. Our previous bioinformatics study revealed that significant CDC6 overexpression in gliomas was closely correlated with poor patient prognosis. Through qPCR, western blotting, and immunohistochemistry, we will further validate CDC6 expression in clinical glioma specimens, while the effects of silencing and overexpressing CDC6 in the U87 and LN229 glioma cell lines on malignancy will be assessed through MTS, EdU, transwell, and migration assays. Luciferase reporter assays, ChIP, qPCR, and western blotting were used to explore the upstream and downstream molecular mechanisms of CDC6. Our study confirmed the abnormal overexpression of CDC6 in gliomas, particularly in glioblastomas. CDC6 promotes glioma cell activity, proliferation, invasion, and migration by activating the IL6-mediated JAK2/STAT3 signaling pathway. The transcription Factor E2F8 directly regulates CDC6 transcription, playing a crucial role in its abnormal overexpression in gliomas. This research provides vital evidence supporting CDC6 as a molecular target for glioma therapy.

Elevated SH3 and Multiple Ankyrin Repeat Domains 2 Expression Correlates With Improved Glioma Prognosis.

This study investigates the prognostic significance of SH3 and multiple ankyrin repeat domains 2 (SHANK2) gene expression in glioma patients, using data from The Cancer Genome Atlas (TCGA), the Genotype-Tissue Expression (GTEx) project, and the Gene Expression Omnibus (GEO). Through comprehensive analysis, we found a significant association between higher SHANK2 expression and improved survival outcomes across various glioma subtypes. To further validate the clinical relevance of SHANK2, we conducted cellular experiments involving siRNA-mediated knockdown of SHANK2 in U87 and A172 glioma cell lines. Quantitative real-time PCR (qPCR) and Western blot analyses confirmed the successful knockdown of SHANK2, and subsequent MTT assays revealed that silencing SHANK2 significantly promoted glioma cell proliferation. These findings underscore the potential role of SHANK2 as a tumor suppressor in glioma. The study also introduces a multivariate prognostic model incorporating SHANK2, providing a novel perspective on glioma prognosis. While the retrospective nature of the study presents limitations, our results suggest that SHANK2 expression could serve as a valuable biomarker for glioma prognosis and inform future therapeutic strategies.

Preparation of transferrin-targeted temozolomide nano-micelles and their anti-glioma effect.

This study aims to develop brain-targeted temozolomide (TMZ) nanograins using the biodegradable polymer material PEG-PLA as a carrier. The model drug TMZ was encapsulated within the polymer using targeted nanotechnology. Key characteristics such as appearance, particle size, size distribution, drug loading capacity, in vitro release rate, stability, and anti-tumor effects were systematically evaluated through in vitro experiments. Transmission electron microscopy (TEM) and Malvern size analyzer were employed to observe the morphological and particle size features of the TMZ nanospheres at various time points to assess stability. The effects of TMZ nanograins on glioma cell viability and apoptosis were evaluated using MTT assays and flow cytometry. The targeted TMZ nano-micelles were successfully synthesized. After loading and targeted modifications, the particle size increased from 50.7 to 190 nm, indicating successful encapsulation of TMZ. The average particle size of the nano-micelles remained stable around 145 ± 10 nm at 1 day, 15 days, and 30 days post-preparation. The release rate of the nano-micelles was monitored at 2 h, 12 h, 24 h, and 48 h post-dialysis, ultimately reaching 95.8%. Compared to TMZ alone, the TMZ-loaded PEG-PLA nano-micelles exhibited enhanced cytotoxicity and apoptosis in glioma cells. This was accompanied by increased mitochondrial membrane potential and reactive oxygen species (ROS) levels following treatment with the TMZ nano-micelles. TMZ-loaded nano-micelles demonstrated a gradual release profile and significantly enhanced inhibitory effects on human glioma U251 cells compared to TMZ alone. The findings suggest that TMZ-loaded PEG-PLA nano-micelles may offer a more effective therapeutic approach for glioma treatment.

The CircHAS2/RPL23/MMP9 Axis Facilitates Brain Tumor Metastasis

Abstract Background: Circular RNAs (circRNAs) regulate tumor development by interacting with microRNAs. However, limited research has been conducted on the roles of circRNAs in gliomas. Therefore, we sought to demonstrate the function and molecular mechanism of circHAS2 in gliomas. Methods: CircHAS2, hsa-miR-508-3p, RPL23, and MMP9 mRNA levels were assessed with qRT-PCR. RPL23 and MMP9 protein levels were determined with western blotting and immunohistochemical staining. Glioma cell migration and invasion were assessed with Transwell assays. The interaction between hsa-miR-508-3p and circHAS2 or RPL23 was predicted with RNAhybrid and miRanda, and confirmed through luciferase reporter assays. The effects of circHAS2 on glioma cells were demonstrated in a nude mouse orthotopic xenograft glioma model. Results: We computationally analyzed the differentially expressed circRNAs in glioma tissues by using the GEO database. The screening indicated that circHAS2 was located primarily in the cytoplasm. Functionally, silencing of circHAS2 inhibited glioma migration and invasion. Mechanically, hsa-miR-508-3p was identified as a downstream target of circHAS2. CircHAS2 was found to regulate RPL23 and influence MMP9 via hsa-miR-508-3p, thereby promoting glioma migration and invasion. Moreover, inhibition of circHAS2 impeded the progression of U87 glioma cells in vivo. Conclusion: CircHAS2 regulates RPL23 and subsequent MMP9 expression by sponging hsa-miR508-3p in glioma cells.

Radiosynthesis and in-vitro identification of a molecular probe 131I-FAPI targeting cancer-associated fibroblasts.

Fibroblast activation protein (FAP) is highly expressed in the mesenchyme of most malignant epithelial tumors, while its expression is low in normal tissues. FAP inhibitors (FAPIs) bind specifically to FAP and are used for tumor-targeted diagnosis and therapy. The aim of this study was to radiosynthesize a novel molecular probe 131I-FAPI and evaluate its in-vitro targeting and biological characteristics. The structurally modified FAPI was labelled with 131I through the chloramine-T method. The radiolabeling rate was then detected by thin-layer chromatography (TLC). The stability of 131I-FAPI was determined at PBS (room temperature) and serum (37°C). Its hydrophilicity was calculated by measuring its lipid-water partition coefficient. Pancreatic cancer PANC-1 cell line and glioma U87 cell line were cultured in vitro. Cell uptake assay was used to show the binding ability of 131I-FAPI. The CCK-8 assay was used to calculate the inhibitory effects of 131I-FAPI at different time points (4h, 8h, 12h, 24h, 48h) after comparing with the 131I and FAPI. The before-and-after-24h scratch areas of the two cells were determined in order to verify the effect of 131I-FAPI on the migration ability of the cells. The radiolabeling rate was (84.9 ± 1.02) %. The radiochemical purity of 131I-FAPI remained over 80% in both 25°C PBS and 37°C serum. The value of the lipid-water partition coefficient was -0.869 ± 0.025, indicating the hydrophilic of the probe. The cellular uptake assay showed that U87 cells had a specific binding capacity for 131I-FAPI. In cell inhibition assays, the inhibitory effect of 131I-FAPI on U87 cells increased with time. The results of cell scratch assay showed that 131I-FAPI had the strongest inhibitory effect on the migratory ability of U87 cells compared with 131I and FAPI (P<0.001). 131I-FAPI was synthesized with good in-vitro stability and hydrophilic properties. It can be specifically bound by U87 cells. The proliferation and migration of U87 cells can be effectively inhibited. 131I-FAPI is promising to become a therapeutic probe.

Methionine restriction of glioma does not induce MGMT and greatly improves temozolomide efficacy in an orthotopic nude-mouse model: A potential curable approach to a clinically-incurable disease

Glioma is a highly recalcitrant disease with a 5-year survival of 6.8 %. Temozolomide (TMZ), first-line therapy for glioma, is more effective in O6-methylguanine-DNA methyltransferase (MGMT)-negative gliomas than in MGMT-positive gliomas as MGMT confers resistance to TMZ. Methionine restriction is effective for many cancers in mouse models including glioma. The concern is that methionine restriction could induce MGMT by decreasing DNA methylation and confer resistance to TMZ. In the present study, we investigated the efficacy of combining methionine restriction with TMZ for the treatment of MGMT-negative glioma, and whether methionine restriction induced MGMT. Human MGMT-negative U87 glioma cells were used to determine the efficacy of TMZ combined with methionine restriction. Recombinant methioninase (rMETase) inhibited U87 glioma growth without induction of MGMT in vitro. The combination of rMETase and TMZ inhibited U87 cell proliferation more than either agent alone in vitro. In the orthotopic nude-mouse model, the combination of TMZ and a methionine-deficient diet was much more effective than TMZ alone: two mice out of five were cured of glioma by the combination. No mice died during the treatment period. Methionine restriction enhanced the efficacy of TMZ in MGMT-negative glioma without inducing MGMT, demonstrating potential clinical promise for improved outcome of a currently incurable disease.

Transmembrane and Ubiquitin-Like Domain-Containing 1 Promotes Glioma Growth and Indicates Unfavorable Prognosis.

Ubiquitin-related proteins have garnered increasing attention for their roles in tumorigenesis. Transmembrane and ubiquitin-like domain-containing 1 (TMUB1) is a recently discovered protein in the ubiquitin-like domain family, yet its involvement in glioma remains poorly understood. This study is aimed at investigating the functional significance and clinical relevance of TMUB1 in glioma. We conducted a comprehensive analysis using two cohorts: a retrospective glioma cohort from our hospital and The Cancer Genome Atlas (TCGA) cohort. The mRNA levels of TMUB1 were assessed through reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Clinical associations of TMUB1 in these cohorts were evaluated using correlation tests, chi-square tests, and survival analyses. Additionally, we performed TMUB1 knockdown in U87 and LN-229 human glioma cell lines, and cellular growth was assessed through the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Our results revealed that TMUB1 expression was elevated in glioma tissues compared to normal brain tissues. Notably, lower TMUB1 expression correlated with favorable characteristics such as lower World Health Organization (WHO) grade and 1p/19q codeletion. Moreover, patients with higher TMUB1 levels in glioma tissues exhibited worse prognosis in both TCGA cohort and our retrospective cohort, underscoring its prognostic significance in gliomas. Cellular experiments demonstrated that TMUB1 silencing suppressed the growth of glioma cells. TMUB1 emerges as a novel and clinically relevant prognostic biomarker for gliomas. Targeting TMUB1 holds promise as a potential strategy for glioma treatment. This study contributes valuable insights into the multifaceted role of TMUB1 in glioma pathogenesis and its potential as a diagnostic and therapeutic target.

ApoE—functionalization of nanoparticles for targeted brain delivery—a feasible method for polyplexes?

The blood–brain barrier (BBB) poses a major obstacle in the treatment of all types of central nervous system (CNS) diseases. Small interfering RNA (siRNA) offers in principle a promising therapeutic approach by downregulating disease-related genes via RNA interference. However, the BBB is a formidable barrier for macromolecules such as nucleic acids. In an effort to develop a brain-targeted strategy for siRNA delivery systems formed by electrostatic interactions with cationic polymers (polyplexes (PXs)), we investigated the suitability of the well-known surfactant-based approach for Apolipoprotein E (ApoE)-functionalization of nanoparticles (NPs). The aim of this present work was to investigate if ApoE coating of siRNA PXs formed with cationic branched 25-kDa poly(ethyleneimine) (b-PEI) and nylon-3 polymers without or after precoating with polysorbate 80 (PS 80) would promote successful delivery across the BBB. We utilized highly hydrophobic NM0.2/CP0.8 nylon-3 polymers to evaluate the effects of hydrophobic cyclopentyl (CP) subunits on ApoE binding efficacy and observed successful ApoE binding with and without PS 80 precoating to the nylon-3 but not the PEI polyplexes. Accordingly, ApoE-coated nylon-3 polyplexes showed significantly increased uptake and gene silencing in U87 glioma cells but no benefit in vivo. In conclusion, further optimization of ApoE-functionalized polyplexes and more sophisticated in vitro models are required to achieve more successful in vitro-in vivo translation in future approaches. Graphical abstract

Retrovirus-like gag protein Arc/Arg3.1 is involved in extracellular-vesicle-mediated mRNA transfer between glioma cells

BackgroundActivity-regulated cytoskeleton-associated (Arc) protein is predominantly expressed in excitatory glutamatergic neurons of vertebrates, where it plays a pivotal role in regulation of synaptic plasticity. Arc protein forms capsid-like particles, which can encapsulate and transfer mRNA in extracellular vesicles (EVs) between hippocampal neurons. Once glioma cell networks actively interact with neurons via paracrine signaling and formation of neurogliomal glutamatergic synapses, we predicted the involvement of Arc in a process of EV-mediated mRNA transfer between glioma cells. Materials and methodsArc expression in three human glioma cell lines was evaluated by WB and immunocytochemistry. The properties of Arc protein/mRNA-containing EVs produced by glioma cells were analyzed by RT-PCR, TEM, and WB. Flow cytometry, RT-PCR, and fluorescent microscopy were used to show the involvement of Arc in EV-mediated mRNA transfer between glioma cells. ResultsIt was found that human glioma cells can produce EVs containing Arc/Arg3.1 protein and Arc mRNA (or “Arc EVs”). Arc EVs from U87 glioma cells internalize and deliver Arc mRNA to recipient U87 cells, where it is translated into a protein. Arc overexpression significantly increases EV production, alters EV morphology, and enhances intercellular transfer of highly expressed mRNA in glioma cell culture. ConclusionThese findings indicate involvement of Arc EVs into mRNA transfer between glioma cells that could contribute to tumor progression and affect synaptic plasticity in cancer patients.