Glioma is the common, most aggressive and poorest prognostic tumor type in the brain. More and more biomarkers associated with glioma treatment, prognosis, and immunity are being discovered. Here, we aimed to explore the underlying biological functions and prognostic predictive value of Apolipoprotein L4 (APOL4) in glioma. We downloaded the expression data of APOL4 and clinical information from several databases and used R software for preprocessing. The clinical significance of APOL4 in a glioma outcome was explored by the Cox regression analysis and Kaplan–Meier survival analysis. In addition, immune infiltrates and microenvironmental indicators were assessed by CIBERSORT and TIMER. GO and KEGG analyses were used to analyze the potential functions of APOL4 in gliomas. APOL4 expression was increased in glioma specimens compared to normal tissues and correlated dramatically with the WHO grade. A survival analysis showed a shorter overall survival (OS) in glioma patients with APOL4 overexpression, and a Cox regression analysis showed that APOL4 was an independent prognostic factor for the OS of glioma patients. GSEA, GO, and KEGG enrichment analyses showed remarkable enrichment in immune-related pathways. APOL4 expression was positively correlated with immune infiltration (including DC cells, neutrophils, CD8+ T cells, B cells, macrophages, CD4+ T cells, etc.) and microenvironmental parameters (including immune, stromal, and ESTIMATE scores) in gliomas. Glioma patients with a higher expression of APOL4 may be more sensitive to immune checkpoint inhibitors (ICI). In conclusion, these findings suggest that APOL4 is associated with the tumor grade and immune infiltrates; APOL4 may be a new and potential biomarker for therapeutic and prognostic evaluations that may further suggest the therapeutic efficacy of immunotherapy.

中文翻译：

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APOL4，一种新型免疫相关的胶质瘤预后生物标志物

神经胶质瘤是大脑中常见、最具侵袭性和预后最差的肿瘤类型。越来越多的与胶质瘤治疗、预后和免疫相关的生物标志物正在被发现。在这里，我们旨在探索载脂蛋白 L4 (APOL4) 在胶质瘤中的潜在生物学功能和预后预测价值。我们从几个数据库中下载了 APOL4 的表达数据和临床信息，并使用 R 软件进行预处理。通过 Cox 回归分析和 Kaplan-Meier 生存分析探讨了 APOL4 在胶质瘤结果中的临床意义。此外，免疫浸润和微环境指标通过 CIBERSORT 和 TIMER 进行评估。GO和KEGG分析用于分析APOL4在胶质瘤中的潜在功能。与正常组织相比，胶质瘤标本中的 APOL4 表达增加，并且与 WHO 分级显着相关。生存分析显示 APOL4 过表达的胶质瘤患者的总生存期 (OS) 较短，Cox 回归分析显示 APOL4 是胶质瘤患者 OS 的独立预后因素。GSEA、GO 和 KEGG 富集分析显示免疫相关通路显着富集。APOL4 表达与胶质瘤的免疫浸润（包括 DC 细胞、中性粒细胞、CD8+ T 细胞、B 细胞、巨噬细胞、CD4+ T 细胞等）和微环境参数（包括免疫、基质和 ESTIMATE 评分）呈正相关。APOL4 表达较高的胶质瘤患者可能对免疫检查点抑制剂 (ICI) 更敏感。综上所述，这些发现表明 APOL4 与肿瘤分级和免疫浸润有关；APOL4 可能是一种新的潜在生物标志物，用于治疗和预后评估，可能进一步表明免疫疗法的治疗效果。