目的 探讨膀胱癌源性外泌体长链非编码RNA（long non-coding RNA， lncRNA）CIAT1在肿瘤集体侵袭中的作用及其分子机制，评估其临床相关性及潜在应用价值。 方法 首先通过高通量测序筛选出在膀胱癌及淋巴转移膀胱癌组织外泌体中高表达的lncRNAs，并进一步通过扩大临床样本验证其在膀胱癌组织外泌体中的表达情况。通过构建过表达和敲低CIAT1的膀胱癌细胞，我们在体外实验证实了CIAT1外泌体靶向肿瘤相关成纤维细胞（cancer-associated fibroblasts， CAFs）进而诱导肿瘤细胞集体侵袭的功能。接着通过RNA pull-down、RNA免疫沉淀（RNA immunoprecipitation， RIP）、双荧光素酶报告基因实验、染色质RNA免疫共沉淀（Chromatin isolation by RNA purification， ChIRP）及染色质免疫共沉淀（Chromatin immunoprecipitation， ChIP）等实验探究了CIAT1通过与hnRNPA2B1互作并调控N-cadherin的转录、进而调控膀胱癌集体侵袭的分子机制。 结果 高通量测序（差异倍数> 1.5，P < 0.05）和临床样本验证（P < 0.01）证实CIAT1在膀胱癌组织外泌体中相对表达高于癌旁正常组织外泌体。体外实验证实外泌体CIAT1被CAFs靶向摄取，进而通过调控CAFs显著促进膀胱癌的集体侵袭能力，过表达CIAT1组相比对照组共培养模型的集体侵袭链总数目和总长度均上调（均P < 0.01）。在机制上，CIAT1通过结合hnRNPA2B1被包装进入外泌体，并被CAFs靶向摄取后调控N-cadherin启动子组蛋白H3K4me3修饰而激活N-cadherin的转录，并且过表达CIAT1组相比对照组共培养模型的集体侵袭链总数目和总长度均上调（均P < 0.01）；而与过表达CIAT1同时阻断N-cadherin组相比，对照组共培养模型的集体侵袭链总数目和总长度无显著变化，差异无统计学意义（均P > 0.05）；即阻断N-cadherin可逆转CIAT1对膀胱癌集体侵袭的促进作用。进一步临床数据相关性分析证实CIAT1调控的N-cadherin与膀胱癌患者集体侵袭密切相关（P < 0.01）。 结论 膀胱癌源性外泌体CIAT1能够靶向CAFs调控其N-cadherin转录，进而促进膀胱癌集体侵袭。

Objective To investigate the role and molecular mechanisms of bladder cancer-derived exosomal long non-coding RNA （lncRNA） CIAT1 in mediating collective invasion and to evaluate its clinical significance and potential therapeutic value. Methods High-throughput sequencing was used to identify lncRNAs that are highly expressed in exosomes from bladder cancer and lymph node metastatic tissues. CIAT1 was selected for further validation in clinical bladder cancer samples. By constructing CIAT1-overexpressing and knockdown bladder cancer cells， we demonstrated in vitro that CIAT1-contained exosomes target cancer-associated fibroblasts （CAFs） to induce collective invasion. The underlying mechanism of CIAT1 in bladder cancer collective invasion was explored through RNA pull-down， RNA immunoprecipitation （RIP）， dual-luciferase reporter assays， chromatin isolation by RNA purification （ChIRP） and chromatin immunoprecipitation （ChIP）. Results CIAT1 was significantly upregulated in exosomes derived from bladder cancer tissues compared to adjacent normal tissues by High-throughput sequencing （fold change > 1.5， P < 0.05） and clinical sample validation （P < 0.01）. In vitro experiments， exosomal CIAT1 was selectively internalized by cancer-associated fibroblasts （CAFs）， significantly enhancing collective invasion of bladder cancer via regulating CAFs. In co-culture models， CIAT1 overexpression group showed increased total number and total length of collective invasion chains compared to the control group （P < 0.01 for both）. Mechanistically， CIAT1 was packaged into exosomes via binding to hnRNPA2B1， and internalized by CAFs， where it activated N-cadherin transcription by modulating H3K4me3 histone modification at the N-cadherin promoter. Consistently， the CIAT1 overexpression group exhibited elevated collective invasion chain numbers and lengths compared to the control group （P < 0.01 for both）. However， blocking N-cadherin reversed the pro-invasive effects of CIAT1， with no significant differences in chain numbers or lengths between the CIAT1 overexpression + N-cadherin blockade group and controls （P > 0.05 for both）. Further clinical correlation analysis confirmed that CIAT1-regulated N-cadherin is closely associated with collective invasion in bladder cancer patients （P < 0.01）. Conclusions Exosomal CIAT1 derived from bladder cancer cells targets CAFs to activate N-cadherin transcription， thereby promoting bladder cancer collective invasion.