LncRNA MRPL23-AS1结合EZH2调控上皮间质转化促进涎腺腺样囊性癌肺转移的作用和机制研究

Salivary adenoid cystic carcinoma (SACC) is characterized by invasion and pulmonary metastasis, and the underlying molecular mechanisms remain to be elucidated. We have founded that the epithelial-mesenchymal transition (EMT) and exosomes involved in the invasion and pulmonary metastasis of SACC, and that epiregulin could facilite the EMT and promote the lung metastasis via exosomes. We screened the lncRNA array of epiregulin-overexpressed SACC-83 cells, and found that a long non-coding RNA (lncRNA), MRPL23-AS1, is upregulated in a subset of SACC tisssues or exosomes derived from the plasma of SACC patients, and correlated with SACC lung metastasis. Moreover, MRPL23-AS1 could faciliate EMT by downregulating the expression of E-cadherin. By RNA-pulldown assay, we found that MRPL23-AS1 could bind EZH2, which is likely to involve the EMT regulation by binding to the promotor region of E-cadherin to repress its expression. We intend to further study the underlying mechanism of MRPL23-AS1 in promotion of pulmonary metastasis of salivary adenoid cystic carcinoma, as well as detect its expression in SACC tissues and plasma exosomes. The results of this study will elucidate the mechanism that MRPL23-AS1 promotes the pulmonary metatstsis and prove that MRPL23-AS1 maybe a target and prognostic marker.

远处肺转移是涎腺腺样囊性癌（SACC）主要致死原因之一，分子机制尚未阐明。申请人前期发现epiregulin可通过上皮间质转化（EMT）和外泌体途径促进SACC肺转移。在此基础上经过筛选发现长链非编码RNA MRPL23-AS1在部分SACC患者肿瘤组织及血浆外泌体中高表达，且与SACC肺转移密切相关，MRPL23-AS1可下调EMT标志分子E-cadherin，从而正向调控EMT，RNA-pulldown发现MRPL23-AS1可结合EZH2，有可能增强EZH2对E-cadherin的抑制进而促进EMT。本实验拟深入研究MRPL23-AS1调控EMT促进SACC肺转移的分子机制，并在患者肿瘤标本和血浆外泌体中分析MRPL23-AS1与SACC肺转移和预后的相关性，力求从非编码RNA角度解释SACC易发生肺转移的生物学行为，为SACC肺转移提供治疗靶点及预后指标。

项目背景：远处肺转移是影响涎腺腺样囊性癌患者生存期的主要因素，阐明肺转移的相关分子机制可为SACC肺转移提供有效的临床治疗策略。本文首次发现长链非编码RNA MRPL23-AS1在SACC中表达显著上调且与患者的肺转移和总生存期相关，但其作用及相关机制尚不明确。本研究以MRPL23-AS1为研究目标，阐明其在肿瘤细胞上皮间充质转化过程和肿瘤转移前微环境中的作用，并探讨MRPL23-AS1在SACC肺转移中的作用机制。.研究内容：包括MRPL23-AS1的临床相关性研究；体内、体外的MRPL23-AS1分子功能研究；MRPL23-AS1的分子机制研究。.重要结果：MRPL23-AS1为EREG下游调控的lncRNA；MRPL23-AS1在SACC组织中高表达，且与EREG呈显著正相关性。MRPL23-AS1特异性表达于SACC细胞，并主要定位于细胞核中；MRPL23-AS1高表达与SACC预后较差相关（P < 0.05）。MRPL23-AS1促进SACC细胞EMT和体内肺转移。MRPL23-AS1与EZH2蛋白结合并促进EZH2与E-cadherin启动子区域的结合和启动子区H3K27的三甲基化。MRPL23-AS1通过外泌体促进SACC细胞EMT和肺血管内皮细胞通透性增加，并升高内皮细胞中VEGFA，降低E-cadherin、VE-cadherin的表达，但对ZO-1的表达并无趋势一致的影响。富含MRPL23-AS1的外泌体促进SACC细胞体内肺转移能力。.科学意义：MRPL23-AS1可通过与EZH2结合抑制E-cadherin的表达，促进SACC细胞EMT，通过外泌体增加肺血管内皮细胞通透性进而促进肺转移。MRPL23-AS1可能作为控制SACC肺转移的生物标志物和治疗靶点。