Department of Translational Medicine and Physiology, Elson S. Floyd College of Medicine, Washington State University, Spokane, WA 99202, USA.
Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA.
Int J Mol Sci. 2024 Nov 14;25(22):12231. doi: 10.3390/ijms252212231.
Fatty acid binding protein 7 (FABP7) is a multifunctional chaperone involved in lipid metabolism and signaling. It is primarily expressed in astrocytes and neural stem cells (NSCs), as well as their derived malignant glioma cells within the central nervous system. Despite growing evidence for FABP7's tumor-intrinsic onco-metabolic functions, its mechanistic role in regulating the brain tumor immune microenvironment (TIME) and its impact on prognosis at the molecular level remain incompletely understood. Utilizing combined transcriptome profiling and pan-cancer analysis approaches, we report that FABP7 mediates the expression of multiple onco-immune drivers, collectively impacting tumor immunity and clinical outcomes across brain cancer subtypes. An analysis of a single-cell expression atlas revealed that FABP7 is predominantly expressed in the glial lineage and malignant cell populations in gliomas, with nuclear localization in their parental NSCs. Pathway and gene enrichment analysis of RNA sequencing data from wild-type (WT) and Fabp7-knockout (KO) mouse brains, alongside control (CTL) and FABP7-overexpressing (FABP7 OV) human astrocytes, revealed a more pronounced effect of FABP7 levels on multiple cancer-associated pathways. Notably, genes linked to brain cancer progression and tumor immunity (ENO1, MUC1, COL5A1, and IL11) were significantly downregulated (>2-fold) in KO brain tissue but were upregulated in FABP7 OV astrocytes. Furthermore, an analysis of data from The Cancer Genome Atlas (TCGA) showed robust correlations between the expression of these factors, as well as FABP7, and established glioma oncogenes (EGFR, BRAF, NF1, PDGFRA, IDH1), with stronger associations seen in low-grade glioma (LGG) than in glioblastoma (GBM). TIME profiling also revealed that the expression of FABP7 and the genes that it modulates was significantly associated with prognosis and survival, particularly in LGG patients, by influencing the infiltration of immunosuppressive cell populations within tumors. Overall, our findings suggest that FABP7 acts as an intracellular regulator of pro-tumor immunomodulatory genes, exerting a synergistic effect on the TIME and clinical outcomes in brain cancer subtypes.
脂肪酸结合蛋白 7(FABP7)是一种多功能伴侣蛋白,参与脂质代谢和信号转导。它主要在中枢神经系统的星形胶质细胞和神经干细胞(NSCs)及其衍生的恶性神经胶质瘤细胞中表达。尽管越来越多的证据表明 FABP7 具有肿瘤内在的代谢功能,但它在调节脑肿瘤免疫微环境(TIME)及其在分子水平上对预后的影响的机制作用仍不完全清楚。利用联合转录组谱分析和泛癌分析方法,我们报告 FABP7 介导多种致癌免疫驱动因子的表达,共同影响脑癌亚型的肿瘤免疫和临床结局。单细胞表达图谱分析表明,FABP7 在神经胶质瘤中的胶质谱系和恶性细胞群中表达,在其亲本 NSCs 中定位于核内。对 WT 和 Fabp7-KO 小鼠脑以及对照(CTL)和 FABP7 过表达(FABP7 OV)人星形胶质细胞的 RNA 测序数据进行通路和基因富集分析,发现 FABP7 水平对多种癌症相关通路的影响更为显著。值得注意的是,与脑癌进展和肿瘤免疫相关的基因(ENO1、MUC1、COL5A1 和 IL11)在 KO 脑组织中显著下调(>2 倍),但在 FABP7 OV 星形胶质细胞中上调。此外,对来自癌症基因组图谱(TCGA)的数据进行分析表明,这些因子以及 FABP7 的表达与已建立的神经胶质瘤癌基因(EGFR、BRAF、NF1、PDGFRA、IDH1)之间存在显著相关性,在低级别神经胶质瘤(LGG)中相关性更强比胶质母细胞瘤(GBM)更强。TIME 分析还表明,FABP7 和它调节的基因的表达与预后和生存显著相关,特别是在 LGG 患者中,通过影响肿瘤内免疫抑制细胞群的浸润。总的来说,我们的研究结果表明,FABP7 作为一种细胞内的促肿瘤免疫调节基因调节剂,在脑癌亚型的 TIME 和临床结局中发挥协同作用。