Objective:To investigate the expression level of bone marrow stromal antigen 2 (BST2) in patients with glioblastoma (GBM) gene and its correlation with DNA methylation level and prognosis.Methods:The datasets of GBM samples from the Cancer Genome Atlas (TCGA) database (35 cases), GSE22891 cohort (50 cases) within Gene Expression Omnibus (GEO) database, and China Glioma Genome Atlas (CGGA) database (105 cases), and non-tumor brains (NTB) (10 cases in TCGA database, 6 cases in GSE22891 cohort, 5 cases in CGGA database were used to make comparisons of gene expression level; 25 cases in GSE63347 cohort, 4 cases in GSE22891 cohort, 8 cases in CGGA database were used to make comparisons of methylation data). Based on gene expression chip and DNA methylation microarray data from public GBM databases, the expression level of BST2 gene in GBM and the association with non-CpG island DNA methylation, GBM molecular subtypes [CpG island methylation phenotype (G-CIMP) and non-G-CIMP proneural, neural, classical, mesenchymal], overall survival (OS) time and functional gene expression profiles were obtained by using intra-group comparison of BST2 gene expression level between GBM and NTB, survival analysis, and bioinformatic analysis.Results:Compared with NTB samples, BST2 mRNA was highly expressed in GBM (mRNA expression data were based on Z-score standardization) (TCGA database vs. GSE63347 cohort: -0.97±1.14 vs. -2.32±0.21, t = 3.74, P < 0.05; GSE22891 cohort: 9.03±1.28 vs. 7.18±0.22, t = 3.42, P < 0.05; CGGA database: -0.43±1.11 vs. -0.62±0.35, t = 2.09, P < 0.05). In TCGA database, BST2 mRNA was highly expressed in different tumor molecular subgroups (G-CIMP: -1.96±0.94; non-G-CIMP proneural: -1.74±0.88; neural: -0.83±0.98; classical: 0.71±1.18; mesenchymal: -0.55±1.01), which were compared with NTB samples (-2.32±0.21), and the differences were statistically significant (all P < 0.05). There were no statistically significant differences in the expressions of BST2 mRNA in the neural, classical, mesenchymal tumors (all P > 0.05), but the expression of BST2 mRNA in above three groups was higher than that in G-CIMP group and non-G-CIMP proneural group (all P < 0.05). Correlation analysis showed that non-CpG island DNA methylation level of BST2 was negatively correlated with the expression of its mRNA (TCGA database: r = -0.30, P < 0.05; GSE22891 cohort: r = -0.54, P < 0.05; CGGA database: r = -0.29, P > 0.05). Survival analysis showed that BST2 mRNA expression level of non-G-CIMP and non-proneural patients was negatively associated with OS ( HR = 1.18, 95% CI 1.00-1.39, P < 0.05); among those tumors with G-CIMP or proneural subtypes, BST2 mRNA expression was not associated with OS ( HR = 1.08, 95% CI 0.84-1.40, P > 0.05). Bioinformatic analysis showed that among non-G-CIMP and non-proneural samples of TCGA database, GBM samples with higher BST2 expression were enriched with functional gene sets related to negative regulation of immune responses and activation of nuclear factor κB (NF-κB) pathway. Conclusions:The upregulated expression of BST2 gene in GBM may be associated with non-CpG island DNA hypomethylation alteration. BST2 gene may become a potential prognostic biomarker for non-G-CIMP and non-proneural GBM.

Objective:To study the correlations of micro RNA (miR)-432 expression with cell proliferation and migration, and tripartite motif containing protein 38 ( TRIM38) gene expression in isocitrate dehydrogenase ( IDH) wild-type glioma, and overall survival (OS) of these patients. Methods:(1) The miRNA expression microarray data of 198 glioma patients (81 with IDH mutant, 106 with IDH wild type and 11 with unknown type) and 5 nontumorous brain tissues (controls) were downloaded from China Glioma Genome Atlas (CGGA); expression differences of miR-432 between IDH mutant and IDH wild type glioma subgroups and normal controls were compared. According to the median value of miR-432 expression in IDH wild-type glioma samples, these patients were divided into miR-432 high expression group ( n=51) and miR-432 low expression group ( n=53), Kaplan-Meier survival analysis was used to compare the OS, univariate and multivariate Cox regression analyses were used to determine the factors influencing OS, and Pearson correlation was used to analyze the relation between miR-432 expression and TRIM38 gene expression. (2) Human glioma cell line U251 was routinely cultured and divided into nonsense sequence control group and miR-432 mimics group; CCK-8 assay was used to detect the cell viability on the 1 st-5 th d of cultivation; Transwell assay was used to detect the cell migration; quantitative reverse transcription PCR (RT-qPCR) was used to detect the TRIM38 mRNA expression. (3) According to the binding sites between miR-432 and TRIM38 gene predicted by miRNA target gene prediction database, the wild-type TRIM38 3'-terminal untranslated region (3'-UTR) and mutant TRIM38 3'-UTR sequences were designed; U251 cells were divided into miR-432 nonsense sequence+wild-type TRIM38 3'-UTR group, miR-432 mimics+wild-type TRIM38 3'-UTR group, miR-432 nonsense sequence+mutant TRIM38 3'-UTR group, and miR-432 mimics+mutant TRIM38 3'-UTR group; the luciferase activity in these 4 groups was detected by microplate assay. Results:(1) The miR-432 expression in IDH wild-type glioma was significantly decreased as compared with that in the IDH mutant one ( P<0.05). The OS of patients in the miR-432 low-expression group was significantly shorter as compared with that in the miR-432 high-expression group ( P<0.05). Age, glioma grading, and miR-432 expression were significantly correlated with OS of IDH wild-type glioma patients ( P<0.05), but miR-432 expression level was not an independent influencing factor for OS ( P>0.05). The miR-432 and TRIM38 mRNA expressions in IDH wild-type glioma samples were negatively correlated ( r=-0.255, P=0.018). (2) As compared with nonsense sequence control group, miR-432 mimics group had significantly lower cell activity on the 2 rd-5 th d of cultivation, significantly smaller number of migrated cells, and statistically decreased TRIM38 mRNA expression ( P<0.05). (3) The luciferase activity of cells in the miR-432 mimics+wild-type TRIM38 3'-UTR group was significantly lower than that in the miR-432 nonsense+wild-type TRIM38 3'-UTR group ( P<0.05). Conclusion:The miR-432 expression is low in IDH wild-type glioma tissues, and it is associated with poor prognosis of these patients; miR-432 overexpression can inhibit the proliferation and migration of glioma cells, which may be related to its specific binding of TRIM38 gene and interference the expression of this gene.