lncRNA-SNHG5通过影响Twist/Mi2/NuRD蛋白复合物活性调控胃癌EMT进展的研究

Epithelial-mesenchymal transition (EMT) is the process of tumor cells obtaining ability of invasion and migration, which participates in development and progression in tumors including gastric carcinoma (GC) and closely correlates with the prognosis and survival of GC patients. Previously studies indicated that long noncoding RNA SNHG5 could inhibit the ability of invasion and metastasis of GC cells through influencing subcellular location of tumor metastasis-associated gene 2 (MTA2). MTA2 is the vital component of proteins complex Twist/Mi2/NuRD, in which Twist is the most important transcription factor that regulated EMT and interact with MTA2 directly. Our previous results showed that epithelial cells morphology was shown in GC cells after overexpression of SNHG5; in addition, E-cadherin and ZO-1 were upregulated while N-cadherin and Vimentin were downregulated significantly. All these clues indicate that lncRNA-SNHG5 might play a important role in tumor EMT progression of GC. What’s the relationship between SNHG5 and EMT? Whether SNHG5 regulates the progression of EMT? How Twist/Mi2/NuRD complex participates in SNHG5 function for EMT and what’s the exact mechanisms? We attempt at explain these question by means of Co-IP, ChIP, EMSA, immunofluorescence and gene interference in GC xenograft model, for the purpose of discovering and establishing molecular targets of prevention and therapy in gastric cancer.

上皮-间质转化（EMT）使肿瘤细胞获得易发生侵袭转移的表型，参与胃癌的恶性进展及不良预后。我们前期研究发现lncRNA-SNHG5通过影响MTA2的亚细胞定位而抑制胃癌的侵袭和转移。MTA2为核小体重塑去乙酰化酶复合物Twist/Mi2/NuRD的重要成员，与此复合物中EMT重要相关转录因子Twist直接结合。预实验研究发现, 在胃癌细胞中过表达SNHG5后细胞出现上皮细胞形态转变，E-cadherin和ZO-1表达升高而N-cadherin 和Vimentin表达下降。提示我们，SNHG5可能在胃癌EMT进展中发挥重要作用。 SNHG5是否通过与MTA2的结合参与胃癌的EMT进程？Twist/Mi2/NuRD复合物在SNHG5调控胃癌EMT进程中有何作用？具体的分子生物学机制如何？本研究将通过Co-IP、ChIP、EMSA、免疫荧光染色及裸鼠胃癌移植瘤模型中基因干预等方法解答上述问题。

胃癌是全世界发病率占第四位、死亡率占第二位的常见恶性肿瘤。复发与侵袭转移是当今胃癌治疗的难点和重点之一，分子信号调控网络异常是其发生发展的分子生物学基础，同时也是我们有的放矢地确定治疗靶点和策略的契入点。上皮-间质转化（Epithelial-mesenchymal transition， EMT）是指上皮细胞失去上皮细胞表型转化为间质细胞的复杂过程。越来越来多的研究表明，EMT 在肿瘤包括胃癌的侵袭和转移中发挥重要作用。我们在前期研究中发现长链非编码RNA-SNHG5在胃癌组织中呈明显低表达，升高SNHG5的表达可在体外细胞学水平和动物体内水平抑制胃癌细胞的增殖、侵袭转移和克隆形成能力。本课题研究对SNHG5参与胃癌上皮-间质转化（EMT）的作用及机制进行了进一步的深入研究。研究结果发现，SNHG5在胃癌患者肿瘤组织中低表达，E-cadherin在胃癌患者肿瘤组织中低表达，N-cadherin及Vimentin在胃癌患者肿瘤组织中高表达，在胃癌患者组织及外周血中，SNHG5与E-cadherin的表达呈明显正相关，而与N-cadherin及Vimentin的表达呈明显负相关。过表达SNHG5可以抑制胃癌细胞EMT相关标志物N-cadherin及Vimentin的表达，升高CDH1的表达，而敲低SNHG5可以促进胃癌相关标志物N-cadherin及Vimentin的表达，降低CDH1的表达。细胞核浆蛋白分提和免疫荧光实验表明，SNHG5可阻止MTA2和Twist进入细胞核，并可以抑制Twist与E-cadherin启动子区的结合，从而阻止Twist/ Mi2/NuRD 复合物结合至E-cadherin的启动子区 ，进而逆转该复合物对E-cadherin表达的抑制。体内实验表明SNHG5 过表达可阻止胃癌细胞荷瘤裸鼠体内肿瘤组织的EMT进展。本研究进一步明确了长链非编码RNA SNHG5作为抑癌基因在肿瘤EMT恶性转化过程中的逆转作用和机制，为胃癌的分子和基因治疗提供实验依据。本课题研究依照计划顺利完成. 课题组人员发表带有课题号的SCI论文8篇，中文核心期刊论文4篇，申请专利1项。并正在撰写SCI论文1篇。