LncRNA Linc00152和LOC100126784在胃癌发生发展中的作用及分子机制研究

Abstract:. Gastric cancer remains to be the third leading morbidity and mortality in China. Currently, increasing evidence demonstrates that long non-coding RNAs (lncRNAs) play important roles in cancer development. Therefore，the clarification of lncRNA regulatory mechanisms in gastric cancer is helpful to develop novel and effective target-theraputic strategies. Our previous study has performed lncRNA microarry detection and identified a specific lncRNA profiling to discriminate gastric cancer tissues from normal counterparts. Linc00152 was most upregulated and LOC100126784 was most downregulated in the signature and their aberrant expression were significantly correlated with poor prognosis of gastric cancer patients. We firstly reported that Linc00152 has oncogenic functions; however its underlying mechnisms in gastric cancer progression is still to be elucidated. Our recent results demonstrated that Linc00152 could function as competing endogenous RNA (ceRNA) for miR193b, overexpressing Linc00152 could decrease miR193b level and abrogate the tumor suppressive roles of miR193b, which may account for an important oncogenic mechanism of Linc00152. Additionally, Linc00152 was able to interact with proteins specifically, and these proteins may be related to cancer development and are involved in tumorigenic effects of Linc00152. In this study, we will extensively investigate how Linc00152 to promote gastric cancer development, including mechanisms of Linc00152 acting as ceRNA for miR193b, but also Linc00152 cooperating with proteins. LOC100126784 is a novel lncRNA with unknown function and the low expression of LOC100126784 is remarkably correlated with shorter survival time in gastric cancer patients. Our results indicated that LOC100126784 could trigger apoptosis, and associate with caner-related proteins such as VDAC1 and 14-3-3ξ that have critical roles in apoptosis and signaling pathway transduction. Additionally, DNA methyltransferase (DNMT) could modulate LOC100126784 expression. In this project, methylation sequening will be employed to analyze the association of LOC100126784 level with its epigenetic modificaton. We will elaborate the molecular mechamisms of LOC100126784 in supressing gastric cancer development by interacting with VDAC1 and 14-3-3ξ proteins as well. Moreover, this project will detect the levels of Linc00152, LOC100126784 and other candidate lncRNAs in plasma of gastric cancer patients, and evaluate their clinical translational potential as novel biomarkers in early diagnosis and predicting prognosis. Taken together, this study devotes to illustrate the molecular mechanisms of Linc00152 and LOC100126784 in gastric cancer pathogenesis in order to provide novel and useful lncRNA diagnostic, prognostic and theraputic targets. This porject is meaningful to drive precise medical development via assessing promising lncRNA biomarker for clinical application.

胃癌在我国发病率和死亡率高居第三位。研究lncRNA在胃癌中的重要调控作用有助于开发新型靶向性诊疗方案。对胃癌lncRNA芯片筛查及检测发现，差异表达的Linc00152和LOC100126784都与患者预后差显著相关。我们曾首次报道Linc00152有促癌功能，后续还发现它有ceRNA潜能，能减少miR193b水平并阻遏后者的抑癌作用。Linc00152还能与蛋白互作，这可能也是其重要促癌途径。本项目将全面阐释Linc00152促进胃癌发展的分子机制。LOC100126784是全新且功能未知的lncRNA，它能结合VDAC1和14-3-3ξ等肿瘤相关蛋白并能促进细胞凋亡，甲基化能影响其表达。本项目将深入研究LOC100126784受甲基化调控及其抑制胃癌进展的机制。此外，我们将评估血浆中这两个lncRNA在胃癌早期诊断和预后预测中的应用价值，为开展精准医疗提供有价值的lncRNA标记物。

胃癌发病率和死亡率高居我国恶性肿瘤第三位，已成为威胁人民健康的重大疾病。LncRNA 在肿瘤发生发展过程中起重要作用。本课题组前期结合多组学分析技术，鉴定出能将胃癌和癌旁组织相区分的lncRNA 特征性表达谱，并从中筛选出 Linc00152和GAS5等一系列重要lncRNA进行了功能和调控机制研究。在国家自然科学基金81672378的支助下，本课题发现Linc00152能作为内源竞争性RNA结合并减少miR-193表达，同时miR-193还能靶向沉默Linc00152转录，但具有抑癌功能的miR-193在胃癌中显著低表达，这可能是导致Linc00152上调并增强其促癌功能的潜在机制。另外，本课题还发现LOC100126784在LncRNA表达谱中显著下调表达，并且低表达该lncRNA的胃癌患者预后差，生存时间更短。深入研究发现， LOC100126784能抑制细胞增殖、使细胞周期停滞在G1期、并诱导细胞凋亡。体内实验也证实该lncRNA能抑制肿瘤生长和肺转移的发生。此外，本课题还对LncRNA表达谱中最显著高表达的lncRNA PVT1开展了深入研究。首次发现PVT1的850-1770 nt区域与信号转到因子STAT3结合，这一互作能保护STAT3蛋白免受蛋白酶体途径降解，提高其蛋白稳定性，促进STAT3下游VEGFA的转录表达，进而招募内皮细胞在肿瘤中形成新生血管。另外，PVT1还能增强STAT3与Slug启动子区的结合，促进Slug转录表达，重塑胃癌细胞，使其发生上皮-间质转化，同时获得血管内皮细胞特性形成血管拟态样结构。这些结果表明PVT1可以通过多种途径促进胃癌的血管生成。进一步研究表明，STAT3也能激活PVT1的转录表达，这一正反馈环路进一步增强了PVT1的促癌作用。上述研究提示，PVT1-STAT3通路是胃癌抗血管治疗的重要靶点。本项目对lncRNA的临床转化潜能也进行了研究，鉴定并验证了一个能预测胃癌患者术后生存的分子标签，高风险患者生存时间更短、易于形成免疫抑制微环境，并且高表达PD-1和PD-L1，这提示这类患者可能从免疫检查点阻断治疗中获益。上述研究成果相继在Oncogene、Cellular Oncology和Am J Cancer Res等国际肿瘤学知名期刊上发表，为新型胃癌诊疗策略的开发提供了基于lncRNA层面的重要理论依据。