粒细胞特异表达的长链非编码RNA—HOTAIRM1在神经胶质瘤中的新功能和作用机制研究

Glioma is the most common and the most aggressive primary brain tumor. Up until recently, the effect of clinical treatment on glioma has a poor prognosis. The more specific and effective molecular markers remain still lacked for accurate subtype diagnosis and prognosis evaluation of glioma. HOTAIRM1, a myeloid-specific long non-coding RNA, was significantly up-regulated compared with normal brain tissues in the glioma samples from different databases. But we still don't know its precise function and mechanism in gliomas. Our previous studies showed that its expression was obviously increased in classical and mesenchyma subtypes of glioma tissues, and negatively correlated with the prognosis of the patients. Knockdown of its expression could effectively inhibit the glioma cell proliferation capacity in vitro and in vivo, and particularly weaken the function of cellular mitochondrial respiratory. Through the analysis of gene expression profile microarray, we also found that HOTAIRM1 would regulate the expression of the mitochondrial serine catabolic enzyme, SHMT2 (serine hydroxymethyltransferase 2). Based on the previous work, this project will furtherly study the effect of HOTAIRM1 on mitochondrial function of glioma cells and the molecular mechanism in the regulation of SHMT2. This work will reveal the novel feature and mechanism of a long non-coding RNA in glioma.

神经胶质瘤是最常见,最具侵袭性的原发性脑肿瘤。目前对胶质瘤治疗的效果不佳，缺乏特异、有效的分子标志物对其分型和预后进行准确的诊断与评估。HOTAIRM1作为粒细胞中特异表达的长链非编码RNA，在不同的胶质瘤样本数据库中都显示较正常脑组织中的表达显著上调，但并不知道它在胶质瘤中的具体功能和作用机制。我实验室在前期研究中发现它在经典和间质亚型的胶质瘤中高表达，并且与患者的预后呈负相关。敲低其表达可有效抑制胶质瘤细胞体外和体内的增殖能力，并且显著抑制细胞线粒体功能。我们还通过基因表达谱芯片，发现HOTAIRM1可以调节线粒体中的丝氨酸分解酶SHMT2的表达。本项目旨在进一步探索HOTAIRM1对胶质瘤线粒体功能的影响和对SHMT2的分子调节机制。该工作将揭示长链非编码RNA在神经胶质瘤中的新功能和新机制。

项目背景：.我实验室在前期工作中，通过整合CGGA和TCGA数据库，发现长链非编码RNA（lncRNA）——HOTAIRM1表达在高级别胶质瘤中显著高于低级别胶质瘤，并且与胶质瘤分子分型和预后评估相关。敲低HOTAIRM1后可以显著抑制胶质瘤细胞的增殖、侵袭和体内成瘤能力。通过基因表达谱芯片筛选，我们发现敲低HOTAIRM1可以下调丝氨酸羟甲基转移酶2（SHMT2）的表达。该酶只存在于线粒体中，能催化丝氨酸分解成甘氨酸。这提示我们HOTAIRM1在胶质瘤中的作用可能不依赖于已知的维甲酸通路或者HOXA基因。..本项目的研究内容主要为：.1、HOTAIRM1在神经胶质瘤中表达水平和表达模式的鉴定。.2、HOTAIRM1在神经胶质瘤中的功能研究。.3、HOTAIRM1下游作用靶基因的筛选和鉴定。.4、HOTAIRM1对候选靶基因SHMT2的调控机制及SHMT2在胶质瘤细胞中的生物学作用。..重要结果和关键数据为：.1、我们鉴定了HOTAIRM1调控下游靶基因SHMT2过程中的关键蛋白PTBP1和IGF2BP2，并且证明HOTAIRM1既可以影响胶质瘤细胞线粒体功能和丝氨酸代谢，又可以参与胶质瘤干细胞自我更新能力的维持。.2、我们还在与HOTAIRM1相互作用的RNA结合蛋白PTBP1的基因位点上发现了一条新的反义RNA——PTB-AS，揭示了PTB-AS在转录后水平调节PTBP1表达的分子机制。.3、我们对胶质瘤中PTBP1调控选择性剪接的lncRNA进行了系统筛选。.4、通过芯片分析，我们发现除了HOTAIRM1，反义RNA——HOXD-AS2表达变化最为显著，该基因可参与调控胶质瘤细胞周期。..科学意义：.以上研究结果不但拓宽了我们对反义RNA在胶质瘤中新功能的认识，加深了我们对RNA结合蛋白与非编码RNA相互作用网络新机制的理解，还为胶质瘤的代谢治疗提供了新靶点SHMT2的研究依据。