肿瘤源性外泌体lncRNA-SELL介导MDSCs促进口腔鳞癌EMT和侵袭转移的机制

LncRNAs in tumor cell-derived exosome(TDE) play an important role in tumor immune regulation. It has been shown that TDE can affect the recruitment and function of MDSCs which closely relate to the invasion and metastasis of tumor cell in tumor inflammational microenvironment. So, we put forward scientific hypothesis on the basis of previous results:LncRNA-SELL in exosomes of oral squamous cell carcinoma (OSCC) mediates EMT and the invasion and metastasis of tumor cells by promoting the functions of MDSCs in the microenvironment. Based on this hypothesis, RNA pull-down, RIP, laser scanning confocal microscope and gene chip technologies are proposed to explore whether lncRNA-SELL can influence the recruitment, secretion and function of MDSCs in OSCC; whether TDE plays a key role in MDSCs regulating the EMT and metastasis of OSCC. And which specific key molecules and signaling pathways are involved in regulating MDSCs-mediated invasion and metastasis of OSCC? The data will explore the molecular mechanism of TDE-lncRNA-SELL regulating MDSCs-mediated invasion and metastasis of oral squamous cell carcinoma from a new perspective of lncRNAs in TDE, and also provide evidence for tumor inflammatory microenvironment promoting tumor invasion and metastasis.

lncRNAs是肿瘤源性外泌体（TDE）调节肿瘤免疫的重要效应分子。近来研究显示：TDE可调控肿瘤炎症免疫微环境中与侵袭转移密切相关MDSCs的募集和功能。基于此，申请人在前期研究基础上提出科学假设：口腔鳞癌（OSCC）源性的外泌体lncRNA-SELL通过促进微环境中MDSCs功能介导口腔鳞癌EMT和侵袭转移。围绕此假设，拟用RNA pull-down、RIP、激光共聚焦显微镜和基因芯片等技术，探讨：口腔鳞癌细胞lncRNA-SELL能否影响MDSCs募集、分泌和功能？TDE是否在MDSCs介导口腔鳞癌肿瘤免疫抑制中起重要作用？TDE-lncRNA-SELL通过哪些关键分子和信号通路在MDSCs促进口腔鳞癌EMT和侵袭转移中发挥作用？研究结果将从lncRNAs新视野，诠释TDE调控MDSCs介导口腔鳞癌侵袭转移的分子机制，进一步丰富肿瘤炎症微环境促进肿瘤侵袭转移的理论内涵。

口腔鳞状细胞癌（OSCC）是口腔最常见的恶性肿瘤，与HPV-OSCC相比，HPV+OSCC患者具有易发生淋巴结转移、放疗敏感和预后好独特临床特征，但其5年生存率仍低于60%，因此，研究HPV+ OSCC恶行进展的分子机制和寻找潜在的治疗靶点至关重要。本项目采用lncRNAs芯片筛选在HPV+OSCC/HPV- OSCC/正常口腔粘膜组织中差异表达的lncRNAs，探究在HPV+ OSCC中高表达的lncRNA SELL对HPV+ OSCC细胞增殖、迁移、侵袭能力和诱导巨噬细胞极化和MDSCs募集能力影响及机制，结果显示：临床标本上，lncRNA SELL在HPV+ OSCC组织中过表达，且与患者的肿瘤体积大小和淋巴结转移呈正相关；L-selectin在HPV+ OSCC组织中过表达，且与患者淋巴结转移呈正相关；lncRNA SELL与L-selectin在HPV+ OSCC组织中表达呈正相关。细胞上，lncRNA SELL促进HPV+ OSCC细胞增殖、迁移、侵袭，介导HPV+ OSCC诱导巨噬细胞M1型极化和MDSCs募集。HPV+ OSCC细胞中lncRNA SELL的表达受HPV16 E6调控，lncRNA SELL通过E6/lncRNA SELL/GATA3/L-selectin促进HPV+ OSCC迁移、侵袭和诱导TAMs M1型极化。动物模型上，成功构建HPV16-E6/E7转基因小鼠，转基因小鼠OSCC组织中L-selectin表达更高，OSCC组织中浸润的CD68+CD80+ TAMs更多，MDSCs浸润数量无明显变化；在HPV16-E6/E7转基因小鼠中，fucoidan抗L-selectin治疗抑制OSCC形成和侵袭转移，但对OSCC组织中浸润的CD68+ CD80+ 巨噬细胞浸润和MDSCs无影响。研究结果为靶向治疗HPV+ OSCC提供新思路。