Objective: To investigate neuregulin 2 (NRG2) expression in gliomas and its role in glioma development.
Methods: We compared the expression levels of NRG2 and glial fibrillary acidic protein (GFAP) in low-grade glioma (LGG) and glioblastoma multiforme (GBM) with those in normal control samples using GEPIA database.The correlation between NRG2 and GFAP expression and their association with the overall survival of patients with LGG and GBM were analyzed.Immunohistochemical staining was used to detect NRG2 protein expression levels in a tissue microarray consisting of human gliomas of different grades, and potential co-localization of NRG2 and GFAP was analyzed using a double-labeling immunofluorescence assay.Western blotting was used to investigate the effect of perifosine (an AKT inhibitor) on the regulation of GFAP expression by NRG2 in human glioblastoma U-87 MG cells.
Results: Both LGG and GBM tissues, especially the former, exhibited high expressions of NRG2 (P < 0.01).In GBM samples, patients with low NRG2 levels had slightly higher overall survival after 30 months than patients with high NRG2 levels.The expression level of NRG2 mRNA was negatively correlated with that of GFAP in LGG samples (P < 0.01) but positively correlated with GFAP expression in GBM samples (P < 0.01).Immunofluorescence assay showed that NRG2 and GFAP were co-expressed in the same tumor cells of LGG tissues but were separately expressed in different tumor cells in GBM tissues.In U-87 MG cells, treatment with recombinant human NRG2 obviously promoted the expression of GFAP, and this effect was significantly inhibited by perifosine (P < 0.01).
Conclusion: NRG2 is highly expressed in gliomas of different grades and regulates GFAP expression in glioma cells at least partly via the Akt signaling pathway to affect the survival of glioma patients.
目的: 探讨神经调节蛋白2（NRG2）在胶质瘤中的表达及其在胶质瘤发生发展中的作用。
方法: 通过GEPIA数据库比较分析与人正常对照组相比，低级别胶质瘤（LGG，n=518）和胶质母细胞瘤（GBM，n=163）样本中NRG2和GFAP基因表达水平变化，并分析LGG和GBM样本中两个分子与患者生存率的关系，以及两个分子表达相关性。获取人胶质瘤组织芯片样本，包含癌旁正常组织10个、LGG组织48个、GBM组织20个；使用免疫组织化学染色观察不同级别人胶质瘤组织芯片样本中NRG2表达水平变化情况，并使用免疫荧光双标法观察NRG2与GFAP的共定位情况。采用Western blot检测Akt抑制剂Perifosine对NRG2调控GFAP表达的影响。
结果: NRG2在LGG和GBM样本中均存在高表达，以LGG较为显著（P < 0.01）。GBM样本中，低NRG2水平患者的总体生存率在30月之后略高于高NRG2水平患者。在LGG样本中，NRG2与GFAP基因表达水平呈负相关（P < 0.01），而在GBM样本中则呈正相关（P < 0.01）。免疫荧光染色显示LGG样本中NRG2与GFAP多共定位于同一肿瘤细胞，而在GBM样本中则多表达于不同肿瘤细胞。NRG2促进U-87 MG胶质母细胞瘤细胞中GFAP表达，该作用可被Akt抑制剂Perifosine显著抑制（P < 0.01）。
结论: NRG2可高表达于不同级别胶质瘤组织中，可能部分通过Akt信号调控胶质瘤细胞GFAP表达，影响患者生存率。
Keywords: glial fibrillary acidic protein; glioblastoma multiforme; glioma; low-grade glioma; neuregulin 2.