KLF9下调PKM2表达抑制食管鳞癌细胞上皮-间质转化及转移的作用机制研究

Increasing evidence supports a role for epithelial-mesenchymal transitions (EMT) in the acquisition of migratory and invasive properties that promote the dissemination of tumor cells and metastasis. Recent reports further demonstrated that several krüppel-like factors (KLFs) regulate EMT in some different types of cancers. However, the role of KLF9 in the regulation of EMT in esophageal squamous cell carcinoma (ESCC) remains unknown..In a recent work we demonstrated that the expresssion of KLF9 in ESCC tissuses was significantly lower than that in matched normal tissues,and the the expresssion of KLF9 was negatively correlated with metastasis in ESCC patients. In addition, we found that KLF9 significantly repressed the expression of pyruvate kinase M2 (PKM2), which reportedly induces EMT in colon and hepatocellular carcinoma cells. Moreover, over-expression of KLF9 could repress EMT in ESCC cells. Therefore, we hypothesized that KLF9 might inhibit ESCC EMT and metastasis via KLF9 mediated down-regulation of PKM2 expression..In this project, we plan to evaluate the role of KLF9/PKM2 in the EMT of ESCC by multiple approaches including luciferase reporter assay, ChIP-chip, ChIP, lentivirus mediated gene delivery, bioinformatic analysis, metastasis assay in NOD/SCID mice and clinical investigation. .Conceivably, elucidation of the molecular pathways involved in the EMT of ESCC by KLF9/PKM2 will provide important clues for the development and evaluation of novel anticancer therapies.

上皮-间质转化（EMT）与上皮类肿瘤的转移发生密切相关。近年来有关KLF家族调控肿瘤细胞EMT的机制研究取得了一定进展，但目前关于KLF9对肿瘤细胞EMT的调控作用及其机制尚未见报道。前期我们通过临床统计发现，食管鳞癌中KLF9显著低表达且与转移呈负相关，细胞学及动物实验提示KLF9可能通过下调丙酮酸激酶M2（PKM2）表达抑制食管鳞癌细胞EMT及侵袭、转移，但其具体的机制仍有待于进一步明确。本项目拟通过ChIP、荧光素酶报告基因实验明确KLF9抑制PKM2转录表达的机制，采用ChIP-chip、生物信息学分析及细胞功能实验明确PKM2调控EMT的途径，籍此建立KLF9下调PKM2转录表达抑制食管鳞癌EMT的信号通路；此外，通过动物转移成瘤模型及临床统计分析评价KLF9、PKM2以及PKM2靶基因在食管鳞癌转移诊疗中的潜在应用价值，为今后临床开展食管鳞癌转移相关的诊疗新方法提供理论依据。

食管癌是严重威胁人类健康的恶性肿瘤，发病率和病死率逐年升高。我国是食管癌的高发国家，超过80%的食管癌是鳞状细胞癌(ESCC)。ESCC预后很差，5年生存率低于20%。ESCC发病率和死亡率高与其易发生远处转移、治疗后容易复发有关。很多患者确诊时即已发生局部浸润或远处转移，失去了根治的机会。因此，寻找肿瘤发生、发展中的关键因素，为ESCC的诊疗提供新的有效靶点成为目前亟待解决的重要难题。本项目研究发现在ESCC组织和细胞中存在人Krüppel 样因子9（KLF9）的下调和丙酮酸激酶M2（PKM2）的上调，进一步研究显示KLF9可直接调控PKM2的表达，且上调KLF9的表达可显著降低食管癌细胞的侵袭和上皮间之转化（EMT），而这种抑制作用可被PKM2的过表达所抑制；更为重要的是，ESCC患者组织中KLF9的低表达和PKM2的高表达与预后不良相关；此外，本项目研究中还发现，ESCC组织和细胞内miR-370可通过下调肽基脯氨酰顺反异构酶NIMA相互作用蛋白1（PIN1）的表达，抑制ESCC细胞的增殖，促进ESCC细胞凋亡，这很可能与食管癌的发生发展有重要的关系。本项目研究发现的KLF9/PKM2、miR-370/PIN通路均与ESCC的发生、发展密切相关，研究成果有望为ESCC的诊疗开发新的靶点，具有广阔的临床应用前景。