Cai Heng, Xue Yixue, Liu Wenjing, Li Zhen, Hu Yi, Li Zhiqing, Shang Xiuli, Liu Yunhui
Department of Neurosurgery, Shengjing Hospital of China Medical University, Shenyang, 110004, People's Republic of China.
J Neurooncol. 2015 May;123(1):161-9. doi: 10.1007/s11060-015-1780-7. Epub 2015 Apr 10.
Roundabout4 (Robo4), a new member of Robo proteins family, is specifically expressed in endothelial cells. Recent studies have indicated that Robo4 could regulate tumor angiogenesis and vascular permeability. However, the role and function of Robo4 are not well understood. This study was performed to investigate the expression of Robo4 in primary glioma patients, and thus to determine the association of Robo4 expression with microvessel density and survival of glioma patients. In this study, real-time PCR and immunohistochemistry were performed to examine the mRNA level and protein expression of Robo4 in both 43 cases of glioma samples and 10 cases of normal brain tissue samples. The results demonstrated that Robo4 was significantly up-regulated in glioma tissues compared with normal brain tissues. In addition, double immunofluorescent staining revealed that Robo4 expression co-localized with CD34 expression in the vessel of glioma tissues. The expression of Robo4 positively correlated with patients' age (P = 0.0139) and glioma grade (P < 0.0001). A linear correlation was observed between the relative mRNA expression of Robo4 values and corresponding microvessel density values (r = 0.9735, P < 0.0001). Kaplan-Meier analysis and log-rank test result showed that the overall survival of patients with Robo4 high expression was significantly shorter than that of patients with Robo4 low expression (P < 0.001). The results of present study verify that overexpression of Robo4 is related to poor prognosis of primary gliomas patients through correlating with microvessel density.
Roundabout4（Robo4）是Robo蛋白家族的新成员，特异性表达于内皮细胞。近期研究表明，Robo4可调节肿瘤血管生成和血管通透性。然而，Robo4的作用和功能尚未完全明确。本研究旨在调查Robo4在原发性胶质瘤患者中的表达情况，从而确定Robo4表达与胶质瘤患者微血管密度及生存情况的关联。在本研究中，采用实时定量聚合酶链反应（real-time PCR）和免疫组织化学方法检测了43例胶质瘤样本和10例正常脑组织样本中Robo4的mRNA水平和蛋白表达。结果显示，与正常脑组织相比，Robo4在胶质瘤组织中显著上调。此外，双重免疫荧光染色显示，Robo4表达与胶质瘤组织血管中的CD34表达共定位。Robo4的表达与患者年龄（P = 0.0139）和胶质瘤分级（P < 0.0001）呈正相关。观察到Robo4相对mRNA表达值与相应微血管密度值之间存在线性相关性（r = 0.9735，P < 0.0001）。Kaplan-Meier分析和对数秩检验结果显示，Robo4高表达患者的总生存期显著短于Robo4低表达患者（P < 0.001）。本研究结果证实，Robo4的过表达通过与微血管密度相关，与原发性胶质瘤患者的不良预后有关。
