外泌体介导lncRNA-BAT1募集hnRNP L促进膀胱癌侵袭转移的机制研究

The lymph node metastasis is the main reason for poor prognosis in bladder cancer. Our previous studies confirmed that long non-coding RNAs (lncRNAs) play an important role in bladder cancer metastasis. Recently, our results demonstrated that lncRNA-BAT1 is highly expressed in cancer-derived exosomes and involved in the immunoregulation of tumor microenvironment by binding to hnRNP L in bladder cancer cells. Herein, we propose a novel mechanism of lncRNA-BAT1 in promoting bladder cancer metastasis. LncRNA-BAT1 is specifically encapsulated into exosomes and secreted to extracellular tumor microenvironment by interacting with hnRNP L. Then it is uptaken by macrophage endocytosis, enhancing the expression of CCR5 and tumor immune escape, and therefore promotes bladder cancer metastasis. In the present study, through RNA pull down, high through-put sequencing and in vivo model, we will further confirm that lncRNA-BAT1 is involved in tumor immune escape via hnRNP L and promotes the bladder cancer metastasis. The success of this study may reveal new mechanisms for bladder cancer metastasis in the future.

膀胱癌易发生淋巴转移是其预后差的主要原因。我们前期发表研究证实，长链非编码RNA(lncRNAs)在其中起重要作用，调控膀胱癌侵袭转移。近期预实验结果提示：lncRNA-BAT1在膀胱癌肿瘤细胞分泌的外泌体中高表达，通过与靶蛋白hnRNP L结合，参与肿瘤微环境的免疫调控。据此，我们提出lncRNA-BAT1调控膀胱癌转移的新机制: lncRNA-BAT1通过与hnRNP L结合，在其介导的包装机制下特异性包裹入外泌体，分泌至胞外肿瘤微环境，通过内吞作用被CD8+ T淋巴细胞摄取，进而抑制CXCR3表达，诱导肿瘤细胞发生免疫逃逸，促进膀胱癌侵袭转移。本课题拟进一步采用免疫共沉淀、高通量测序和体内免疫模型构建等技术，获得外泌体介导lncRNA-BAT1通过hnRNP L诱导肿瘤细胞免疫逃逸，促进膀胱癌侵袭转移的可靠证据，为确立其作为膀胱癌分子标记和治疗新靶点提供原创性的科学依据。

膀胱癌是我国男性泌尿生殖系统最常见的恶性肿瘤，其发病率呈上升趋势。膀胱癌易发生淋巴转移是其预后差的主要原因。我们前期发表研究证实，外泌体长链非编码RNA(lncRNAs)在调控膀胱癌淋巴转移中起重要作用，然而具体的分子机制尚不清楚。深入阐明外泌体lncRNAs介导膀胱癌淋巴转移的关键分子机制，将为抑制膀胱癌转移提供理论基础，为膀胱癌靶向治疗和预后评估提供新的思路。针对此方面，我们通过高通量测序筛选鉴定出膀胱癌源性外泌体中高表达的lncRNA-BAT1，并扩大临床样本证实外泌体lncRNA-BAT1与膀胱癌患者的淋巴转移和不良预后成正相关。通过体外功能实验，我们证实外泌体lncRNA-BAT1显著促进膀胱癌细胞的增殖侵袭及诱导淋巴管内皮细胞成管能力；体内动物实验证实外泌体介导的lncRNA-BAT1通过抑制CD8+ T细胞浸润诱导肿瘤细胞免疫逃逸，进而促进膀胱癌淋巴转移。在分子机制中，我们发现lncRNA-BAT1与hnRNP L直接结合，证实lncRNA-BAT1在hnRNP L介导下被包裹入外泌体，并分泌至肿瘤微环境中被CD8+ T细胞摄取。在CD8+ T细胞中lncRNA-BAT1与CXCR3启动子结合形成三聚体，并募集hnRNP L至CXCR3启动子介导其发生H3K27me3修饰抑制CXCR3转录，进而介导膀胱癌细胞发生免疫逃逸而促进淋巴转移的发生。本项目详细阐述了外泌体lncRNA-BAT1促进膀胱癌淋巴转移的具体分子机制，为确立外泌体lncRNA-BAT1作为膀胱癌淋巴转移早期诊断的分子标志物及治疗新靶点提供科学依据。在该项目的支持下，共发表SCI文章26篇，其中IF>10分14篇，并多次参加国内外学术会议交流分享最新研究成果；获得国家知识产权局授权实用新型专利2项；顺利完成3名博士研究生和3名硕士研究生的培养工作。