miR-29a调控鼻咽癌上皮间质转化(EMT)发生的分子机制及临床意义

Nasopharyngeal carcinoma (NPC) in endemic areas are frequently found to be undifferentiated subtype with significant malignancy featured by a low rate of local tumor control and a relatively high rate of metastasis. Our preliminary study found that epithelial mesenchymal transition (EMT) phenomenon existed in NPC tissues, and EMT-associated biomarkers were significantly associated with poor prognosis of NPC patients. Moreover, in the analysis of microRNA (miRNA) profiling in NPC, we found miR-29a closely related to the EMT phenomenon was significantly down-regulated in both plasma and tissue of NPC patients, which also demonstrated a postive association with poor prognosis of NPC patients. In the present programme, we will investigate the role of up- or down- regulated expression of miR-29a in modulating the biological behaviors and the EMT phenomenom in vivo and in vitro; explore the influence of genetic variation, methylation and enzymatic activity on downregulating miR-29a expression; screen and validate the target genes of miR-29a by employing the techniques of gene chip, quantitative PCR and luciferase assay; explore associated signal pathways mediated by miR-29a target genes; and finally analyze the association of miR-29a and its target genes with EMT biomarkers, clinical pathological parameters and patient's prognosis. Better understanding in the molecular mechanisms and clinical significance of miR-20a regulating the EMT during the NPC develoment will undoubtedly provide us with new biomarkers or targets for NPC molecular classificaiton and personalized diagnosis and treatment in endemic areas.

高发区鼻咽癌绝大多数为未分化型癌，恶性程度高，放疗后局部控制率低和远处转移率高。本课题组发现鼻咽癌组织存在上皮间质转化（EMT）现象且EMT标志物表达升高与患者预后不良显著相关，我们还在鼻咽癌miRNA差异表达谱分析中发现与肿瘤EMT密切相关的miR-29a在血浆和组织中表达水平均显著下降。本项目拟进一步在体内、外观察过表达或沉默miR-29a对鼻咽癌生物学行为和EMT现象的影响；分析基因变异、甲基化、酶活性对miR-29a低表达的影响；采用基因芯片、定量PCR、荧光素酶报告系统筛选和鉴定miR-29a靶基因，进一步分析靶基因介导的信号通路及其对EMT调控作用；最后分析miR-29a及其靶基因与鼻咽癌EMT分子标志物、临床病理特征和患者预后的相关性，从而阐明miR-29a调控鼻咽癌EMT的分子机制和临床意义，为高发区鼻咽癌分子分型、个体化诊治提供新的标志物或靶点。

鼻咽癌（NPC）是一种上皮源性恶性肿瘤，高发于南非、东南亚尤其是中国南方部分地区。高发区鼻咽癌绝大多数为未分化型癌，恶性程度高，早期可转移至颈部淋巴结，放疗后局部控制率低和远处转移率高，预后不良。本课题组发现鼻咽癌组织存在上皮间质转化（EMT）现象且EMT标志物表达升高与患者预后不良显著相关，我们还在鼻咽癌miRNA差异表达谱分析中发现与肿瘤EMT密切相关的miR-29a在血浆和组织中表达水平均显著下降。本研究的主要内容采用原位杂交检测鼻咽癌原发肿瘤中miR29a的表达情况。采用定量PCR检测鼻咽癌细胞系miR29a的表达；并从体外观察过表达或沉默miR-29a对鼻咽癌细胞生物学行为和EMT现象的影响；分析甲基化对miR-29a低表达的影响。本项目的重要研究结果：体外实验证实miR29a低表达在鼻咽癌侵袭、转移中起着重要作用，为高发区鼻咽癌分子分型、个体化诊治提供新的标志物或靶点。