Pediatric pilocytic astrocytoma (PA) is the most common brain tumor in children. Complete resection provides a favorable prognosis, except for unresectable PA forms. There is an incomplete understanding of the molecular and cellular pathogenesis of PA. Potential biomarkers for PA patients, especially the non-BRAF-mutated ones are needed. Cerebrospinal fluid (CSF) is a valuable source of brain tumor biomarkers. Extracellular vesicles (EVs), circulating in CSF, express valuable disease targets. These can be isolated from CSF from waste extraventricular drainage (EVD). We analyzed the proteome of EVD CSF from PA, congenital hydrocephalus (CH, non-tumor control), or medulloblastoma (MB, unrelated tumoral control) patients. A total of 3072 proteins were identified, 47.1%, 65.6%, and 86.2% of which were expressed in the unprocessed total and in its large-EV (LEV), and small-EV (SEV) fractions. Bioinformatics identified 50 statistically significant proteins in the comparison between PA and HC, and PA and MB patients, in the same fractions. Kinase enrichment analysis predicted five enriched kinases involved in signaling. Among these, only Cyclin-dependent kinase 2 (CDK2) kinase was overexpressed in PA samples. PLS-DA highlighted the inactive carboxypeptidase-like protein X2 (CPXM2) and aquaporin-4 (AQP4) as statistically significant in all the comparisons, with CPXM2 being overexpressed (validated by ELISA and Western blot) and AQP4 downregulated in PA. These proteins were considered the most promising potential biomarkers for discriminating among pilocytic astrocytoma and unrelated tumoral (MB) or non-tumoral conditions in all the fractions examined, and are proposed to be prospectively validated in the plasma for translational medicine applications.
儿童毛细胞型星形细胞瘤（PA）是儿童中最常见的脑肿瘤。除无法切除的PA类型外，完全切除可带来良好预后。目前对PA的分子和细胞发病机制认识尚不全面，尤其需要寻找PA患者（特别是非BRAF突变型）的潜在生物标志物。脑脊液（CSF）是脑肿瘤生物标志物的重要来源，其中循环的细胞外囊泡（EVs）可表达具有疾病指示价值的靶标。这些囊泡可从临床废弃的脑室外引流（EVD）脑脊液中分离获得。本研究分析了PA、先天性脑积水（CH，非肿瘤对照）及髓母细胞瘤（MB，无关肿瘤对照）患者的EVD脑脊液蛋白质组，共鉴定出3072种蛋白质，其中47.1%、65.6%和86.2%分别存在于未处理总样本、大囊泡（LEV）组分和小囊泡（SEV）组分中。生物信息学分析发现，在相同组分中，PA与HC、PA与MB患者的比较中存在50种具有统计学显著差异的蛋白质。激酶富集分析预测出5种参与信号转导的富集激酶，其中仅细胞周期蛋白依赖性激酶2（CDK2）在PA样本中过表达。偏最小二乘判别分析（PLS-DA）显示，失活的羧肽酶样蛋白X2（CPXM2）和水通道蛋白-4（AQP4）在所有比较中均具有统计学显著性：CPXM2在PA中过表达（经ELISA和蛋白质印迹验证），而AQP4表达下调。这些蛋白质被认为是在所有检测组分中区分毛细胞型星形细胞瘤与无关肿瘤（MB）或非肿瘤状态最具潜力的生物标志物，建议后续在血浆样本中进行前瞻性验证，以推动转化医学应用。
肿瘤(癌症)患者之家