剪接蛋白SRSF1在恶性胶质瘤发生发展中的作用及机制研究

Malignant glioma is the most common and highly lethal type of primary brain cancer. Aberrant alternative splicing may be a significant but yet under-explored contributor to the heterogeneous pathological characteristics of malignant gliomas. Our previous results showed that a splicing factor, serine-arginine rich splicing factor 1 (SRSF1) was upregulated in a human glioma microarray. And there is a highly significant correlation between elevated SRSF1 expression and short overall survival of patients. In addition, knockdown of SRSF1 in glioblastoma (GBM) cell lines resulted in proliferation and survival inhibition in vitro. We further found that SRSF1 could modulate alternative splicing of ribosomal S6 kinase 1 gene (S6K1). According to these resluts, we propose the hypothesis that aberrant alternative splicing play an important role in malignant glioma tumorigenesis. In this project, we aim to explore the function and molecular mechanisms of SRSF1 in the tumorigenesis of malignant glioma, by using molecular, cellular biology techniques and animal models, including fully identifying its downstream splicing targets and their relevant roles in the pathogenesis and progression of malignant glioma. Taken together, this project will enrich our knowledge of glioma pathogenesis at the splicing regulation level and provides novel strategies and potential therapeutic targets for malignant glioma treatment.

恶性胶质瘤是最常见的高致死性颅内原发性肿瘤，基因的异常选择性剪接与恶性胶质瘤发展密切相关。我们的前期工作发现：①剪接蛋白SRSF1 mRNA在胶质瘤中表达显著增加，且其高表达的患者生存期更短；②敲低胶质母细胞瘤细胞系中SRSF1表达，可抑制细胞增殖和存活；③SRSF1可调控S6K1基因的选择性剪接。据此提出选择性剪接异常在恶性胶质瘤发生、发展中起重要作用的研究设想。在本研究中，我们将利用一系列生物学技术，在分子、细胞、动物水平，深入研究SRSF1在恶性胶质瘤发生、发展中的作用及分子机制，全面探索其调控的下游靶基因剪接事件及其生物学功能。我们的研究将从剪接调控水平上探讨恶性胶质瘤发病机理，最终为恶性胶质瘤的治疗提供可能的新方法和新靶点。

由剪接因子改变导致的异常选择性剪接与肿瘤发生发展密切相关。越来越多的证据表明，富含丝氨酸/精氨酸剪接因子1（SRSF1）是多种实体瘤的致癌因子，然而其在胶质瘤中的作用及分子机制还未可知。本项研究中，我们发现SRSF1在人胶质瘤组织及细胞系中表达异常升高，且其表达水平与胶质瘤级别、Ki-67阳性指数正相关，与患者生存期负相关。利用RNA-seq，我们系统性地筛选并鉴定了由SRSF1所调控的许多剪接事件，基序分析表明SRSF1调控胶质瘤细胞内选择性剪接的位置依赖性特点。在功能上，SRSF1可促进胶质瘤细胞增殖、存活及侵袭，与之对应的机制是SRSF1可调控肌浆球蛋白1B（MYO1B）基因选择性剪接、促进生成其膜定位的促瘤蛋白亚型。重要的是，MYO1B基因的异常剪接与SRSF1表达相关，且可提示胶质瘤患者较差的预后。进一步的研究表明，由SRSF1介导的MYO1B选择性剪接可通过PDK1/AKT、PAK/LIMK信号通路提高胶质瘤细胞的致瘤潜能。本研究取得的结果揭示了SRSF1作为一个重要的致癌因子，通过调控MYO1B选择性剪接促进胶质瘤发生，可作为潜在的胶质瘤预后标志物和治疗靶点。