长链非编码RNA LINC01420作为ceRNA促进鼻咽癌侵袭转移的分子机制

We previously identified a long non-coding RNA (lncRNA) named long intergenic non-coding RNA 1420 (LINC01420) was significantly overexpressed in nasopharyngeal carcinoma (NPC) biopsies, and strongly associated with metastasis and poor outcomes in NPC patients; however, its biological function remains completely unknown. Our preliminary data demonstrated that LINC01420 knock-down inhibited invasion and migration in NPC cells. By analyzing the gene-expression microarray data of LINC01420 knock-down NPC cells, we hypothesized that LINC01420 might function as a competing endogenous RNA (ceRNA) of mindbomb E3 ubiquitin protein ligase 1 (MIB1) through miR203, and regulates the downstream signaling pathways of MIB1, such as Notch and NF-κB, to promote invasion and migration of NPC cells. Our previous study also identified miR203 as a key component of signaling pathways driven by LMP1 (an oncoprotein of Epstein - Barr virus) in NPC carcinogenesis. In this study we will elucidate two aspects associated with the function of LINC01420 in NPC and the mechanism by which LINC01420 promotes NPC progression. First, LINC01420 enhances invasion and metastasis in NPC cells by modulating the MIB1 gene; second, LINC01420 cooperatively regulates LMP1 downstream signaling pathways. This study will reveal the biological function of LINC01420, and will also provide novel biomarkers and therapeutic targets for NPC.

我们前期在鼻咽癌中发现一个功能不详的长链非编码RNA LINC01420表达上调，且与肿瘤远处转移及患者不良预后密切相关；在鼻咽癌细胞中敲低LINC01420的表达可明显抑制细胞的侵袭与迁移能力。分析敲低鼻咽癌细胞中LINC01420表达前后基因芯片数据结合生物信息学预测，我们提出了LINC01420作为ceRNA通过miR203调控泛素连接酶MIB1及其下游Notch、NF-κB等信号通路促进鼻咽癌侵袭转移的科学假说；而miR203又是EB病毒编码的LMP1促进鼻咽上皮癌变信号通路中的关键节点。本项目将从LINC01420通过MIB1增强鼻咽癌细胞侵袭转移能力，LINC01420通过miR203对LMP1及其下游信号通路的协同调控两方面探讨LINC01420在鼻咽癌侵袭转移过程中的作用和机制。本项目的完成将初步揭示LINC01420的生物学功能，并将为鼻咽癌的诊疗提供新的分子标记和靶点。

本项目发现在鼻咽癌中的长链非编码RNA LINC01420表达上调，且与肿瘤远处转移及患者不良预后密切相关；在鼻咽癌细胞中敲低LINC01420的表达可明显抑制细胞的侵袭与迁移能力。分析敲低鼻咽癌细胞中LINC01420表达前后基因芯片数据结合生物信息学预测，，发现LINC01420上存在miR-203、miR-4458和miR-5192等少数几个miRNAs的结合位点，其中miR-203的结合位点有最低的最小自由能(minimum free energy, MFE, -47.3 kcal/mol)，提示LINC01420与miR-203的结合能力最强；我们进一步通过生物信息学预测了人类基因组中miR-203的所有靶mRNAs，并与敲低LINC01420后鼻咽癌细胞中表达下调的基因列表进行对比，发现MIB1基因mRNA的3’-非翻译区(3’-UTR)也存在miR-203的结合位点，且在敲低LINC01420的细胞中表达显著下调。这些数据提示LINC01420可能通过miR-203与MIB1互为ceRNA。我们利用DAVID (https://david.ncifcrf.gov/) 在线分析软件对敲低LINC01420后鼻咽癌细胞中的差异表达基因进行了初步的功能聚类，排在前五位的分别是Notch、Pathways in cancer、Focal adhesion、NF-κB和ECM-receptor interaction 。LINC01420作为ceRNA通过miR203调控泛素连接酶MIB1及其下游Notch、NF-κB等信号通路促进鼻咽癌侵袭转移。