阿尔茨海默病相关分子标志物APP和MAPT在人脑胶质瘤中的表达及临床意义

The expression and clinical significance of Alzheimer disease related biomarkers APP and MAPT in human gliomas

目的 研究阿尔茨海默病(AD)相关分子标志物APP和MAPT在人脑胶质瘤中的表达水平,及作为脑胶质瘤潜在预后判断标志物和干预靶点的意义。方法 纳入中国脑胶质瘤基因组图谱计划(CGGA)和癌症基因组图谱计划(TCGA)2个数据库中的325个和609个Ⅱ~Ⅳ级胶质瘤患者,收集患者的WHO病理分级、原发或继发状态、IDH突变状态、1p/19q杂合缺失状态、生存期等数据以及APP和MAPT2种基因的表达水平。对基因表达水平进行标准化处理后,比较2种基因在各级别胶质瘤、IDH突变/野生型、1p/19q杂合缺失/野生型中的表达差异。采用Kaplan-Meier(K-M)生存曲线分析2种基因水平与原发、继发胶质瘤预后的关系,并采用Log-rank进行比较。在CGGA和TCGA数据库中筛选与MAPT表达水平相关的基因列表,采用基因本体论(GO)功能富集分析MAPT影响胶质瘤预后的分子机制。结果 在CGGA和TCGA数据库中,Ⅱ、Ⅲ、Ⅳ级胶质瘤患者之间的MAPT表达水平两两比较,差异均有统计学意义(均P<0.01)。在TCGA数据库中,仅Ⅲ、Ⅳ级胶质瘤患者之间的APP表达水平比较,差异有统计学意义(P<0.01)。在CGGA和TCGA数据库中,Ⅱ~Ⅳ级胶质瘤IDH突变型患者的MAPT表达水平均高于IDH野生型患者,差异均有统计学意义(均P<0.01);在TCGA数据库中,Ⅳ级胶质瘤IDH突变型APP表达水平高于野生型患者,差异有统计学意义(P<0.05)。在TCGA数据库中,APP在Ⅱ、Ⅲ级胶质瘤以及MAPT在Ⅲ级胶质瘤患者1p/19q杂合缺失和野生型之间的表达水平比较,差异有统计学意义(P<0.001);在CGGA数据库中,Ⅳ级胶质瘤1p/19q杂合缺失和野生型患者之间的MAPT表达水平比较,差异有统计学意义(P<0.001)。K-M生存曲线分析显示,MAPT基因能够有效判断原发性胶质瘤患者的预后,MAPT表达水平较高的患者预后较好(P<0.001)。GO功能富集分析显示,MAPT表达水平与胶质瘤的肌动蛋白细胞骨架组装、微管蛋白细胞骨架组装、Wnt通路、神经系统发育、以DNA为模板的转录调控、RNA聚合酶Ⅱ启动子转录调控呈正相关,与细胞迁移、细胞黏附、血管生成、细胞分裂、细胞增殖等呈负相关。细胞模型验证发现,MAPT过表达能够抑制胶质瘤细胞的迁移和侵袭能力。结论 MAPT表达水平可以预测原发性胶质瘤患者的预后,且MAPT与胶质瘤恶性程度存在相关性,是胶质瘤研究和治疗的潜在靶点。

Objective To determine the expression of APP and MAPT, two Alzheimer disease related biomarkers in gliomas, and to develop glioma prognosis predicting factors and therapeutic targets.Methods The WHO pathological grade, primary or secondary status, IDH mutation status, 1p/19q heterozygous deletion status, survival period and other data of 325 and 609 patients with grade Ⅱ to Ⅳ glioma included in the two databases of the China Glioma Genome Atlas(CGGA) and the Cancer Genome Atlas(TCGA), as well as the expression level of APP and MAPT genes. After the gene expression level was standardized, the expression differences of the two genes in glioma, IDH mutation/wild-type, 1p/19q heterozygous deletion/wildtype were compared. Kaplan Meier(K-M) survival curve was used to analyze the relationship between APP and MAPT gene levels and the prognosis of primary and secondary glioma, and Log-rank was used for comparison.The list of genes related to MAPT expression level in CGGA and TCGA databases were screened. The molecular mechanism of MAPT affecting the prognosis of glioma was analyzed by gene ontology(GO) function enrichment.Results In CGGA and TCGA databases, the expression level of MAPT in grade Ⅱ to Ⅳ glioma patients was statistically significant(P < 0.01);There was significant difference between two groups in each database(all P<0.01). In TCGA database, there was a statistically significant difference in APP expression level between patients with grade Ⅲ and Ⅳ glioma(P < 0.01). In CGGA and TCGA databases, the expression level of MAPT in IDH mutant patients with grade Ⅱ to Ⅳ glioma was higher than that in IDH wild-type patients, and the difference was statistically significant(P < 0.01). In TCGA database, there was a statistically significant difference in APP expression between IDH mutant and wild-type patients with grade Ⅳ glioma(P < 0.01).In TCGA database, the expression level of APP in grade Ⅱ and Ⅲ glioma and MAPT between 1p/19q loss of heterozygosity and wild-type in grade Ⅲ glioma patients were statistically significant(P < 0.001). In CGGA database, there was a statistically significant difference in MAPT expression between 1p/19q loss of heterozygosity and wild-type patients with grade Ⅳ glioma(P < 0.001). K-M survival curve analysis showed that MAPT gene could effectively judge the prognosis of patients with primary glioma, and patients with higher MAPT expression had better prognosis(P < 0.001). GO function enrichment analysis showed that MAPT expression level was positively correlated with actin cytoskeleton assembly, tubulin cytoskeleton assembly, Wnt pathway, nervous system development, DNA based transcriptional regulation, RNA polymerase Ⅱ promoter transcriptional regulation of glioma, and negatively correlated with cell migration, cell adhesion, angiogenesis, cell division, cell proliferation, etc. Cell model validation found that overexpression of MAPT could inhibit the migration and invasion of glioma cells. Conclusions The expression level of MAPT can predict the prognosis of patients with primary glioma, and there is a correlation between MAPT and the malignant degree of glioma, which is a potential target for glioma research and treatment.