UBA2 as a Prognostic Biomarker and Potential Therapeutic Target in Glioma

Background : Gliomas are characterized by aggressive behavior, leading to severe disability and high mortality. Ubiquitin-like modifier activating enzyme 2 (UBA2) is a subunit of the E1-activating enzyme involved in the SUMOylation (SUMO, small ubiquitin-related modifier) of numerous proteins. Although the abnormality of UBA2 is linked to the progression of various tumor types, the role of UBA2 in glioma is still unknown. Methods : A bioinformatic analysis using several public databases was conducted to examine the expression level, clinicopathological correlations


Introduction
Gliomas are the most frequent primary intracranial tumors and are characterized by aggressive behavior, leading to severe disability and a high rate of mortality [1].They are typically classified into two subgroups: low-grade glioma (LGG; grade 2 and 3) and glioblastoma multiforme (GBM; grade 4) [2].Several molecular markers, including 1p19q codeletion and isocitrate dehydrogenase (IDH) mutation are instrumental in the classification, prognosis, and treatment of gliomas [3].The 2021 World Health Organization (WHO) Classification of Tumors of the Central Nervous System subdivided adult-type diffuse glioma into three types based on histologic patterns and molecular markers: (1) astrocytoma, IDH-mutant; (2) oligodendroglioma, IDH-mutant, and 1p/19q-codeleted; and (3) glioblastoma, IDH-wildtype [4].The prognosis for patients with glioma remains poor, despite the availability of many treatment options, including surgical resection, chemotherapy, radiotherapy, and immunotherapy [5].
Small ubiquitin-related modifiers (SUMOs) are a large family of conserved proteins shared by all eukaryotic organisms [6].SUMOylation is a posttranslational protein modification involved in several biological activities, including transcription and cell signaling [7].A series of events mediated by the SUMO E1 activation enzyme, E2 conjugation enzyme, and several E3 ligases result in SUMOylation [8].The essential elements of E1, responsible for the activation of protein SUMOylation, are SUMOactivating enzyme subunit 1 (SAE1) and ubiquitin-like modifier activating enzyme 2 (UBA2) [9].Of note, several studies have shown that UBA2 expression is strongly correlated to the progression of pancreatic, lung, kidney, and colorectal cancers as well as being overexpressed in a variety of malignancies [7,[10][11][12][13][14].These findings imply that UBA2 is a promising therapeutic target for the management of cancer.However, the role of UBA2 in glioma is still unknown.
The aim of this research was therefore to clarify the expression level of UBA2 in glioma, as well as its clinicopathological correlations and prognostic significance.In addition, the correlation between UBA2 expression and drug sensitivity in cancer was also examined.To accomplish this, a bioinformatic analysis of various public databases was conducted.A series of in vitro cellular experiments further explored the function of UBA2 in glioma.Individualized treatment of gliomas is still being investigated, and there is an urgent need for more research on different targets.The results of the present work show that UBA2 is a promising prognostic biomarker and a potential therapeutic target in glioma.These findings may be important for the management of future glioma patients.

Data Collection, Preprocessing, and Expression Analysis
The UCSC Xena online tool (https://xenabrowser.ne t/datapages/) was used to compile data from the Cancer Genome Atlas (TCGA) and the Genotype-Tissue Expression (GTEx) RNAseq databases in transcripts per million (TPM) format, and together with prognostic data for glioma [15].UBA2 protein levels were analyzed using the University of Alabama at Birmingham Cancer Data Analysis Portal (UALCAN, https://ualcan.path.uab.edu/), and the aforementioned results were verified using the Gene Expression Profiling Interactive Analysis (GEPIA, http://gepia.cancer-pku.cn/)database [16,17].Finally, the diagnostic receiver operating characteristic (ROC) curve was used to determine the ability of UBA2 expression to distinguish between tumor and normal tissue.Youden's index was used to determine the cut-off value for UBA2 expression to classify tumor and non-tumor brain tissue.

Prognostic Value of UBA2 in Glioma and the Nomogram Prognostic Model
The median value of UBA2 mRNA expression in 698 glioma patients from the TCGA dataset was used as the cutoff value to classify patients into low and high expression groups.Kaplan-Meier (K-M) survival analysis was conducted using the R packages "survminer" and "survivor", and survival curves were plotted for both groups.The study endpoints were disease-specific survival (DSS), overall survival (OS), and progression-free interval (PFI).A cohort dataset was also retrieved from the Chinese Glioma Genome Atlas database (CGGA, http://www.cgga.org.cn/) in order to perform survival analysis [18].Univariate analysis using Cox proportional risk regression modelling was first performed to study the link between UBA2 expression and OS.Other clinical and pathological prognostic factors were also evaluated.Subsequently, variables with p values < 0.1 were included in multivariate Cox regression analysis to determine independent correlates of OS.The results were visualized by drawing forest plots using the R package "ggplot2".To assist clinicians in predicting the OS of patients, we constructed a prediction model using the R package "rms" and drew a calibration curve.The nomogram allows visualization of the correlation between each predictor and survival outcome.Each predictor corresponds to a scale of scores, and the sum of the scores for all factors corresponds to the probability of OS at different times.We also developed and validated the DSS and PFI prediction models using the same approach.

Prediction of Drug Sensitivity
The RNAs associated with Drug (RNAactDrug, http: //bio-bigdata.hrbmu.edu.cn/RNAactDrug/)database was used to explore the relationship between UBA2 mRNA expression and drug sensitivity.This online tool contains the Cancer Cell Line Encyclopedia (CCLE), the Genomics of Drug Sensitivity in Cancer (GDSC, formerly known as CGP), and the CellMiner databases.The computational analysis of resistance (CARE) algorithm utilizes compound screening data to identify biomarkers of response to targeted therapies.This contains the Cancer Therapeutic Response Portal (CTRP), CCLE, and CGP databases, and results in a CARE score that reflects drug sensitivity [27].

Cell Culture
Three human glioma cell lines (A172, U251, and U87) and one human normal astrocyte cell line (HA1800) were investigated in this study.The glioma cell lines were obtained from the Institute of Modern Physics, Chinese Academy of Sciences (Lanzhou, China), while the HA1800 cell line was obtained from Mingzhoubio (Ningbo, China).Short Tandem Repeat (STR) analysis was performed to identify the cell lines.All the cell lines were mycoplasma-negative and were cultured at 37 °C with 5% CO 2 in Dulbecco's Modified Eagle Medium with 1% penicillin/streptomycin (Solarbio, Beijing, China) and 10% fetal bovine serum (FBS, ExCell Bio, Soochow, China).

Cell Irradiation
Cells were irradiated using an X-RAY generator (X-RAD 225, North Branford, CT, USA).The dose rate was set to 2.0-3.0Gy/min (225 KV/13.3 mA, 0.2 mm Al filter), and source-skin distance was 40 cm.

Colony Formation Assay
For the colony formation assay, a single cell suspension containing an appropriate number of cells was placed in 60-mm petri dishes.The medium was replaced every 4 days.After 2 weeks of incubation, the cells were fixed in ethanol and 0.1% concentration of crystal violet (Solarbio, Beijing, China) was used to stain the colonies.

Cell Apoptosis and Cycle Assay
Cells were seeded into 6-well plates (2 × 10 5 cells per well) and grown for 48 h.Apoptosis was then measured using flow cytometry and an Annexin V-FITC/PI cell apoptosis analysis kit (Meilunbio, Dalian, China).For the cell cycle assay, cells were fixed in 70% ethanol at -20 °C overnight, stained with DNA staining solution (Liankebio, Hangzhou, China) at room temperature for 30 min, and evaluated by flow cytometry.Modfit LT software5.0.9 (Verity Software House, Bedford, MA, USA) was used to perform cell cycle analysis.

Cell Migration and Invasion Assay
The cell migration assay was performed using 24well transwell chambers (Corning, Kennebunk, ME, USA).Briefly, 3 × 10 4 cells in serum-free medium were added to the upper chamber, and medium containing 15% FBS was added to the lower chamber.Upper chamber cells were removed after 24 h of culture with a damp cotton swab, fixed in methanol, and stained with 0.1% crystal violet (Solarbio, Beijing, China).For the cell invasion assay, the upper chamber was coated with 1:8 Matrigel (BD Biosciences, San Jose, CA, USA), and the remaining experimental procedure was similar to that of the cell migration assay.Finally, the invasive and migrated cells were photographed using a light microscope (Olympus, Tokyo, Japan).

Statistical Analysis
The student's t test or Mann-Whitney U rank-sum test was used to compare UBA2 expression between tumor and normal tissues, depending on the results of the normality test of the samples.These tests were also used to determine correlations between UBA2 expression and clinicopathological variables.The log-rank test was used to perform a K-M survival analysis.The Pearson or Spearman's test was used for correlation analysis.R software 4.2.1 (Ross Ihaka and Robert Gentleman, Auckland, New Zealand) and GraphPad Prism 9.4.0 (Dotmatics, Boston, MA, USA) were employed for all statistical calculations and data visualizations, with the specific R package described in the preceding sections.All p-values in this study were tested using a two-tailed test, with p < 0.05 denoting the statistical significance.All data was presented in the format of means ± standard deviation.

UBA2 Overexpression in Glioma
Pan-cancer analysis of the TCGA-GTEx database revealed that UBA2 was overexpressed in multiple cancers relative to corresponding normal tissues, including glioma (Fig. 1A-C).In the GEPIA, UALCAN, and Clinical Proteomic Tumor Analysis Consortium (CPTAC, https://prot eomics.cancer.gov/programs/cptac)databases, UBA2 expression was substantially higher in glioma compared to normal tissues (Fig. 1D-F).UBA2 protein and mRNA expression in glioma (A172, U251, and U87) and astrocyte (HA1800) cell lines were detected using Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) assays.Compared to the typical astrocyte cell line, glioma cell lines expressed significantly higher levels of UBA2 protein and mRNA (Fig. 1G,H).Furthermore, the diagnostic ROC curve showed that UBA2 expression could effectively differentiate between glioma and normal tissues (Area Under Curve = 0.867, Fig. 1I).The expression level of UBA2 was 5.81 at the maximum Youden's index, indicating this was the optimal cut-off value for distinguishing between glioma and normal tissues (Supplementary Fig. 1).These findings demonstrate that UBA2 is overexpressed in glioma cell lines and tissues.

The Relationship Between Glioma Clinicopathological Parameters and UBA2 Expression
The relationship between UBA2 expression and various clinicopathological parameters in glioma patients was analyzed using the TCGA database (Supplementary Table 1).UBA2 expression in glioma was associated with WHO grade, IDH gene status, histological type, and 1p19q deletion, but not with patient sex, race, or age.UBA2 expression was higher in WHO grade 4 gliomas compared to WHO grade 2 and 3 gliomas (Fig. 2A).Additionally, UBA2 expression was higher in glioblastoma than in astrocytoma, oligoastrocytoma, and oligodendroglioma (Fig. 2C).Patients with 1p19q non-codeletion and IDH-wildtype, both of which are indicators of poor prognosis, showed highly elevated expression of UBA2 (Fig. 2B,D).Together, these findings indicate that UBA2 expression is associated with the malignant progression of glioma.

High UBA2 Expression Predicts Poor Survival in Glioma Patients
K-M analysis to explore the association between UBA2 expression and survival in glioma patients from the TCGA database.Patients with high UBA2 expression showed significantly worse OS, PFI, and DSS than those with low UBA2 expression (Fig. 3A-C).Further subgroup analyses revealed that high UBA2 expression was associated with poorer OS in patients with WHO grade 2 glioma, oligodendroglioma, and IDH mutant glioma, as well as in both male and female patients, aged ≤60 years old, and White individuals (Fig. 3D-J).Similar results were ob-tained following analysis of data from the CGGA database (Fig. 4A,D,H-J).Notably, the association between UBA2 expression and OS in the CGGA database was also found in WHO grade 3 glioma, anaplastic astrocytoma, gliomas with 1p19q non-codeletion, and glioma with methylated or unmethylated methylguanine methyltransferase (MGMT) promoter (Fig. 4B,C,E-G).These findings indicate that high UBA2 expression predictes poor survival in glioma patients.

UBA2 is a Prognostic Biomarker in Patients with Glioma
To further examine whether UBA2 is a prognostic factor for glioma, data from the TCGA database was used to perform univariate and multivariate Cox regression analyses.IDH status, patient age, WHO grade, 1p19q codeletion, sex, and UBA2 expression levels were all significantly associated with OS in univariate analysis (Fig. 5A).Multivariate analysis further revealed that patient age, IDH status, and WHO grade were independent prognostic factors (Fig. 5B).Next, a nomogram was constructed using WHO grade, IDH status, age, and UBA2 expression level to predict 1-year, 3-year, and 5-year OS in glioma patients (Fig. 5C).The calibration curve demonstrated consistency of the observed results with the predicted values (Fig. 5D).Using this method, nomograms for PFI and DSS and their respective calibration curves were also created (Fig. 5E-H).Taken together, these results indicate that UBA2 is a promising prognostic biomarker for glioma.

Relationship Between UBA2 Expression and Tumor-Infiltrating Immune Cells in Glioma
In light of the prognostic significance of tumorinfiltrating immune cells in gliomas, we next evaluated whether UBA2 expression was related to immune cell infiltration.The ssGSEA computational tool was used to compare the distribution of 24 distinct immune cell subpopulations between the high and low UBA2 expression groups.As shown in Fig. 6A, activated dendritic cells (DC), induced DC, macrophages, neutrophils, T helper cells, gamma delta T cells, and T helper type 2 cells were markably increased in the high UBA2 expression group.In contrast, CD8 T cells, DC, mast cells, natural killer (NK) CD56 bright cells, NK CD56 dim cells, plasmacytoid DC, follicular helper T cells (Tfh), Th17 cells, and T-regulatory cells were markedly lower in the high UBA2 expression group (Fig. 6A).Validation was performed with four algorithms, all of which yielded the same results as above (Fig. 6B).The ImmuneScore, EstimateScore, and Stroma-lScore values were all higher in the UBA2 high expression group compared to the low expression group, with all showing a positive linear correlation (Fig. 6C-H).These findings indicate that UBA2 expression is linked to immune cell infiltration in glioma.

Relationship Between UBA2 Expression and Drug Sensitivity
The relationship between UBA2 expression and drug sensitivity was analyzed using the RNAactDrug database.The calculated values showed a relationship between UBA2 expression and the IC50 of drugs.Sensitivities to Nilotinib, Erlotinib, Panobinostat, Sorafenib, Topotecan, and Irinotecan were all positively associated with UBA2 expression (Fig. 7A).A total of 6, 124, and 35 compounds from the CCLE, CTRP, and CGP databases, respectively, were screened by CARE (Fig. 7B).Twenty of these compounds contained in at least two of the databases were selected for visualization and to label their targets, including drugs such as Nilotinib, Sorafenib, Axitinib, Vorinostat, Linifanib, Navitoclax, Cabozantinib, Imatinib, Quizartinib, Abraxane, Topotecan, and Panobinostat.These drugs are already on the market or have been used in clinical trials (Fig. 7C).The findings show that UBA2 expression is associated with the drug sensitivity of cancers.

UBA2 Knockdown Inhibits U87 Cell Progression
To further examine the involvement of UBA2 in glioma development, lentiviruses carrying short hairpin RNA were used for stable knockdown of UBA2 in U87 cells (shUBA2-U87) and for the negative control (shNC-U87).Both the protein and mRNA levels of UBA2 were markedly lower in shUBA2-U87 cells, as determined by Western blotting and qRT-PCR (Fig. 8A,B).U87 cells with the shUBA2-1 sequence were selected for subsequent experiments.The CCK-8 assay showed that knockdown of UBA2 significantly slowed the proliferation of U87 cells (Fig. 8C).shUBA2-U87 cells also showed fewer colonies in the colony formation assay (Fig. 8D).The cell apoptosis assay revealed a significantly higher number of apoptotic shUBA2-U87 cells compared to shNC-U87 cells, suggesting that silencing of UBA2 plays a role in cell apoptosis (Fig. 8E).UBA2 knockdown in U87 cells significantly increased G0/G1 phase cells observed in the cell cycle assay, while reducing the S phase cells (Fig. 8F).Furthermore, shUBA2-U87 cells showed greatly reduced migration and invasion capacities (Fig. 8G).Taken together, these findings demonstrate that UBA2 knockdown suppresses the progression of glioma cells.

UBA2 Knockdown Sensitizes U87 Cells to Irradiation
The CGGA database was used to determine whether UBA2 expression was associated with the outcome of glioma patients after radiotherapy.Individuals with high UBA2 expression levels had a markedly poorer prognosis compared to those with low expression (Fig. 9A).We also investigated whether UBA2 knockdown would sensitize glioma cells to irradiation.The colony formation assay and CCK-8 assay revealed that UBA2 knockdown together with irradiation suppressed cell colony formation and proliferation (Fig. 9B,C).Moreover, the cell apoptosis assay revealed a higher apoptotic rate in irradiated shUBA2-U87 cells than in irradiated shNC-U87 cells (Fig. 9D).In summary, these findings imply that UBA2 knockdown can sensitize glioma cells to irradiation.

Discussion
Gliomas are a large group of heterogeneous neurological tumors.The typing of gliomas is becoming clearer thanks to advances in molecular genetic testing and several clinical trials.Traditional and new treatment protocols are becoming more precise and standardized.These usually involve comprehensive assessment of the patient's clinical presentation, general condition, prognostic factors, and side effects after surgery and chemoradiotherapy.The results of molecular pathology and genetic examinations can provide important prognostic information, as well as guiding the choice of radiotherapy and chemotherapy.Mutations in IDH1 and IDH2 are associated with favorable prognosis, and patients with these mutations respond better to alkylating agents and radiotherapy [28].The combined deletion of chromosome 1p19q is also thought to be a favorable prognostic indicator and a predictor of greater sensitivity to radiotherapy and alkylating agents [29].Methylation of the MGMT promoter in glioblastoma also indicates favorable prognosis and a positive therapeutic effect of temozolomide [30].Several other molecular markers such as H3K27, H3G34, a-thalassemiamentalretardation syndrome X (ATRX ), telomerase reverse tranase (TERT), and miR181d have also been shown to have both diagnostic and prognostic value.

Role of UBA2 in Malignant Tumors
Several previous studies have reported on the role of UBA2 in tumor development.Zhang et al. [14] found that inhibition of UBA2 in clear cell renal cell carcinoma suppressed cell growth, induced apoptosis, and reduced the level of crucial enzymes associated with the p53 mutant, c-Myc, and SUMO modification systems.He et al. [12] reported that UBA2 knockdown in colorectal cancer cells reduced cell proliferation and concurrently increased cell apoptosis through regulation of the P53/murine double minute2 (MDM2)/P21 and phosphatase and tensin homolog deleted on chromosome ten (PTEN)/phosphoinositide 3kinase (PI3K)/protein kinase B (AKT) signaling pathways.Li et al. [31] reported that knockdown of UBA2 inhibited the invasion and migration of gastric cancer cells by regulating the Wnt/β-catenin signaling pathway.In the present study, the majority of malignant tumors expressed high levels of UBA2.Our bioinformatic analysis and in vitro experiments showed that glioma tissue and cell lines expressed high levels of UBA2.Similar to the previous studies, we found that knockdown of UBA2 reduced the ability of glioma cells to proliferate, migrate, and invade, while also enhancing apoptosis and G0/G1 cell cycle arrest.UBA2 expression correlated strongly with IDH status, histological type, WHO grade, and 1p19q codeletion status.Patients with high UBA2 expression had worse prognosis than those with low expression.UBA2 expression could effectively differentiate tumors from normal tissue, and predict OS, PFI, and DSS in glioma patients.These results indicate that UBA2 may be a potentially useful diagnostic and prognostic biomarker for glioma.Additionally, we found that UBA2 expression is linked to drug sensitivity in cancers, suggesting that it may be a useful target for drug therapy in tumors, including glioma.

Immunotherapy of Gliomas and the Potential Role of UBA2
Immune cell infiltration and immune regulation play a significant role in influencing the prognosis of glioma [32].Increased expression levels of inhibitory checkpoint pro-   teins, programmed cell death protein 1 (PD-1) (and its ligand PD-L1), and cytotoxic T lymphocyte-associated protein 4 (CTLA-4) have been correlated with immune evasion, elevated tumor grade, and poor prognosis in glioma patients [33].However, immunotherapy for glioma remains challenging.Nivolumab and pembrolizumab have proven effective in other solid tumors and are now commonly used immune checkpoint inhibitors.However, both have failed to improve OS in several clinical trials of glioma [34][35][36].Immunotherapy for glioma is still being explored, with the main focus currently being on immune checkpoint inhibitors.Recruitment has been completed for a clinical trial of ipilimumab with temozolomide versus temozolomide alone after surgery and chemoradiotherapy in GBM (Ipi-Glio/NCT02311920) [37].In addition to PD-1/PD-L1 and CTLA-4, clinical trials that target other immune checkpoints such as T-cell immunoglobulin and mucin domain 3 (TIM3) and lymphocyte-activation gene 3 (LAG3) are currently ongoing (NCT02658981 and NCT02817633).These will not be discussed further here as several comprehensive reviews have recently summarized the topic of im-munotherapy for glioma, we will not go into detail [38][39][40].The current study found that UBA2 expression was significantly correlated with immune cell infiltration and the tumor microenvironment.This suggests that UBA2 is a key player in immune regulation and may also reflect the status of the immune microenvironment in gliomas.Furthermore, it suggests that UBA2 may be a biomarker of the response to immune checkpoint inhibitors in gliomas, as well as affecting their efficacy.

UBA2 and Radiosensitization in Gliomas
Although radiotherapy is one of the standard treatment modalities for glioma, its efficacy is limited by radioresistance [41].New approaches are therefore needed to improve the efficacy of radiotherapy for glioma.Several studies have shown that SUMOylation or SUMO targets are associated with the development of radioresistance in several tumor types.SUMO-interacting motif mimetic peptides coupled to gold nanoparticles have been observed to inhibit polySUMO-2/3-dependent protein-protein interactions [10].The mechanism by which the SUMO path-  way sensitizes cancer cells to irradiation could therefore be via control of the DNA damage response.SUMOspecific proteases modulate the radiosensitivity of cancer cells through their involvement in various cellular processes [42][43][44][45].Additionally, the combination of SUMOylation inhibitors such as 2-D08 and ML-792 with radiotherapy may improve the outcome of cancer patients [46].SAE1 or UBA2 is a subunit of the E1-activating enzyme involved in the SUMOylation of numerous proteins.The results of the present study are similar to a previous investigation which found that knockdown of SAE1 enhanced the radiosensitivity of colorectal cancer cells [47].We found that knockdown of UBA2 sensitized glioma cells to irradiation, indicating that it may be a target for the radiosensitization of gliomas.

Strengths and Limitations
To our knowledge, this is the first study to correlate the expression of UBA2 in glioma with clinicopathological factors, immune cell infiltration, drug sensitivity, and radiosensitivity.UBA2 is overexpressed in gliomas, and is also closely associated with IDH status, histological type, WHO grade, and 1p19q codeletion status.The prognosis of glioma patients with high UBA2 expression is worse than that of patients with low expression.These findings suggest that UBA2 expression is associated with the progression of gliomas and patient outcomes.It is well-known that the occurrence and advancement of glioma are related to immune cell infiltration, which has been shown to influence tumor progression and prognosis [48].Our results showed that UBA2 expression was positively correlated with several immune cell types, including macrophages, neutrophils, activated DC, induced DC, and T helper cells, but negatively correlated with CD8 T cells, DC, mast cells, NK CD56 bright cells, and NK CD56 dim cells.These findings suggest that UBA2 might participate in regulating immune cell infiltration in glioma.The major tumor-infiltrating cells are macrophages and neutrophils, and the infiltration and polarization of these cells are the main causes of chemotherapy and radiation resistance in gliomas [49].Glioma-associated macrophages (GAMs) act critically in enhancing tumor progression and can alter drug resistance, promoting resistance to radiotherapy and establishing an immunosuppressive environment [50,51].The current study showed that UBA2 expression was related to drug sensitivity in cancers, including glioma.The efficacy of radiotherapy in glioma appears to be constrained by cellular resistance to irradiation [41], with the present study finding that UBA2 knockdown sensitized glioma cells to irradiation.In summary, it seems reasonable to speculate that UBA2 might be involved in drug and irradiation resistance by regulating immune cell infiltration in gliomas.
Several potential biases and shortcomings of this study must be addressed prior to clinical translation.Firstly, public databases such as TCGA and CGGA, contain only limited clinical information.In particular, they lack data on surgical margins/extent of resection, which is a key determinant of prognosis.Moreover, the TCGA database contains only GBM and LGG cohorts.Despite these being the predominant pathological types, they are not completely representative of glioma.In order to validate our findings, future studies should include a larger size of clinical samples and more detailed clinical information.Secondly, the involvement of UBA2 in glioma was not fully elucidated, and further investigations into the molecular mechanisms involved are warranted.

Conclusions
This study found that UBA2 has diagnostic and prognostic value in glioma.UBA2 may also be associated with tumor progression, immune cell infiltration, drug sensitivity, and radiosensitivity in glioma.It could therefore be a potential target for therapy, as well as a biomarker for the diagnosis, prognosis, immune response, drug sensitivity, and radiosensitivity of gliomas.This study provides new insights into the role of UBA2 in the growth and regulation of gliomas.The findings should contribute to the individualized treatment of glioma and may also help to guide clinical practice.

Fig. 7 .
Fig. 7. Relationship between UBA2 expression and drug sensitivity.(A) Lollipop chart shows the correlation between UBA2 expression and drug sensitivity of tumor cells by RNAactDrug.(B) Venn diagram indicates the shared drug of three source using CARE.(C) Visualization of drugs overlapping in (B) and labeling of their targets.CCLE, Cancer Cell Line Encyclopedia; CTRP, Cancer Therapeutic Response Portal; CARE, Computational Analysis of Resistance.