组蛋白H2A去泛素化酶BAP1对恶性胶质瘤细胞发生发展的作用及临床应用价值研究

Research on the Role and Clinical Application Value of the Histone H2A Deubiquitinase BAP1 in the Occurrence and Progression of Malignant Glioma Cells

目的探索乳腺癌/卵巢癌易感基因1相关蛋白1(breast/ovarian cancer susceptibility gene 1 associated protein 1,BAP1)对人源恶性胶质瘤发生、发展的作用与BAP1作为恶性胶质瘤临床诊断标志物的可行性。方法基于基因表达综合数据库(gene expression omnibus,GEO)的子数据集GSE4290,GSE90598,分析BAP1在正常组织及胶质瘤组织中的差异性表达情况;受试者工作特征(receiver operating characteristic,ROC)曲线分析BAP1对恶性胶质瘤的早期诊断价值;选取自主收集的非配对28例恶性胶质瘤患者的原发灶组织、5例颅脑外伤患者内减压术切除的非瘤脑组织,采用实时荧光定量PCR(quantitative real-time polymerase chain reaction,qRT-PCR)检测BAP1的表达水平;利用靶向BAP1的特异性小干扰RNAs(small interfering RNAs,siRNAs)瞬时转染U251细胞系,进一步检测其干涉效率;基于流式细胞仪分析BAP1下调的U251细胞系,其细胞周期、凋亡的变化情况。结果生物信息学结果显示,BAP1在恶性胶质瘤组织中的表达水平均低于正常脑组织(GSE4290:1209±18.49 vs 1476±53.90;GSE90598:5.19±0.10 vs 5.65±0.21),差异具有统计学意义(t=5.115,2.267,均P<0.05)。ROC曲线显示,BAP1可高效区分恶性胶质瘤组织与正常脑组织(GSE4290:AUC=0.78;GSE90598:AUC=0.75,均P<0.05)。临床标本结果显示,BAP1在恶性胶质瘤原发灶组织中的表达水平显著低于非瘤脑组织(0.27±0.04 vs 1.06±0.07),差异具有统计学意义(t=10.22,P<0.001)。在U251细胞系中下调BAP1的表达,其细胞周期中S期细胞比例明显增多,由17.59%分别增至27.21%(siBAP1-1)和25.79%(siBAP1-2),差异具有统计学意义(t=6.576,6.642,均P<0.01),而细胞凋亡水平则有所下降,由10.17%分别降至2.70%(siBAP-1)和3.00%(siBAP-2),差异具有统计学意义(t=10.31,9.428,均P<0.01)。结论组蛋白H2A去泛素化酶BAP1能够通过抑制恶性胶质瘤细胞周期快速进展并促进其凋亡,进而发挥肿瘤抑癌基因的功能,可作为潜在的恶性胶质瘤临床诊断标志物。

Objective To explore the role of breast/ovarian cancer susceptibility gene 1 associated protein 1(BAP1)in the occurrence and progression of human malignant glioma and the feasibility of BAP1 as a clinical diagnostic marker for malignant glioma.Methods The differential expression of BAP1 in normal and glioma tissue was analyzed based on the GSE4290 and GSE90598 sub-datasets from the gene expression omnibus(GEO)database.Receiver operating characteristic(ROC)curve analysis was conducted to assess the early diagnostic value of BAP1 for malignant glioma.Primary lesion tissues from 28 nonpaired malignant glioma patients and non-tumor brain tissues removed by internal decompression surgery in 5 patients with traumatic brain injury collected independently were collected,and the expression levels of BAP1 were measured using quantitative real-time polymerase chain reaction(qRT-PCR).Specific small interfering RNAs(siRNAs)targeting BAP1 were transiently transfected into U251 cells to further evaluate their interference efficiency.Flow cytometry was employed to analyze changes in the cell cycle and apoptosis of U251 cells with BAP1 knockdown.Results The results of bioinformatics showed that the expression of BAP1 in malignant glioma tissues was lower than that in normal brain tissues(GSE 4290:1209±18.49 vs 1476±53.90,GSE 90598:5.19±0.10 vs 5.65±0.21),and the differences were significant(t=5.115,2.267,all P<0.05).ROC curve showed that BAP1 could efficiently differentiate malignant glioma tissue from normal brain tissue(GSE4290:AUC=0.78,GSE90598:AUC=0.75,all P<0.05).The expression level of BAP1 in primary malignant glioma tissue was lower than that in normal brain tissue(0.27±0.04 vs 1.06±0.07),and the difference was significant(t=10.22,P<0.001).After down-regulating the expression of BAP1 in U251 cells,the proportion of S phase cells increased from 17.59%to 27.21%(siBAP1-1)and 25.79%(siBAP1-2),respectively,and the differences were significant(t=6.576,6.642,all P<0.01).However,the apoptosis levels decreased from 10.17%to 2.70%(siBAP-1)and 3.00%(siBAP-2),respectively,and the differences were significant(t=10.31,9.428,all P<0.01).Conclusion Histone H2A deubiquitinase BAP1 could exert the function of tumor suppressor genes by inhibiting rapid cell cycle progression and promoting apoptosis in malignant glioma,and could serve as a potential clinical diagnostic biomarker for malignant glioma.