TGF-β/Smads与IL-6/JAK/STAT信号通路在非小细胞肺癌上皮-间质转化(EMT)过程中协同作用的机制

Metastasis of malignant tumor cells is an important cause for poor prognosis of patients with lung cancer. It has been suggested that epithelial-mesenchymal transition (EMT) process plays important role in induction of lung cancer cell invasion and metastasis. Prior to this proposal, we identified that TGF-β and IL-6 mediated signal pathways were associated with lung cancer(Cancer Res,2009; JCRCO, 2013), and our trial data showed that TGF-β and IL-6 synergistically induced the EMT in A549 cells. Therefore, we hypothesize the presence of regulation mechanisms underlying a synergistic role of TGF-β pathway with IL-6 mediated JAK/STAT pathway in inducing EMT of non-small cell lung cancer (NSCLC).In the present proposal, using several techniques including western blot and shRNA interference and so on, we will first elucidate the mechanisms by which TGF-β and IL-6 synergistically induce and enhance the EMT, and then expect to identify the key cross-talk proteins between TGF-β and IL-6 mediated signal pathways in the induction of EMT process in NSCLC cell lines, lung cancer mouse and tumor tissues. This project will improve our understanding towards the interplay between TGF-β/Smads and IL-6/JAK/STAT in tumor metastasis, and provide new insight into identification of novel efficacious molecular targets for metastatic NSCLC treatment.

癌细胞转移是肺癌患者预后差不良的重要原因。而上皮-间质转化(EMT)是肺癌细胞获得转移侵袭能力的重要生物学过程。我们前期工作证实了TGF-β通路和JAK/STAT通路的IL-6基因与肺癌密切相关（Cancer Res，2009；JCRCO，2013），且预实验表明IL-6能够协同TGF-β诱导A549细胞的EMT过程。因此提出假设：非小细胞肺癌（NSCLC）EMT过程中可能存在TGF-β通路与IL-6介导的JAK/STAT通路协同作用的调控机制。本项目拟采用NSCLC细胞系、组织和小鼠模型等为研究对象，运用western blot、shRNA干扰等技术，阐明TGF-β/Smads与IL-6/JAK/STAT两通路协同诱发和促进EMT过程的机制，预期发现两通路促进EMT的关键节点蛋白，深入解析两通路在NSCLC转移侵袭过程中的协同作用，为发现有效治疗转移性NSCLC的分子靶标提供崭新的思路。

癌细胞转移是肺癌患者预后差不良的重要原因。上皮-间充质转化(Epithelial-mesenchymal transition, EMT)作为癌症转移早期阶段的一个关键步骤，可受多种信号途径的共同调控，包括TGF-β/Smad、JAK/STAT3信号通路。然而，TGF-β/Smad3与JAK/STAT3信号通路在EMT发生过程中的交互作用目前还不是很清楚。本研究中我们主要以肺癌为研究对象，证实了在肺癌细胞株中TGF-β1不仅可以诱导Smad3磷酸化、Snail的表达上调、细胞呈成纤维细胞样形态，同时引起细胞内E-cadherin表达下调以及Vimentin表达上调。SIS3（Smad3磷酸化的抑制剂）可以抑制由TGF-β1诱导的Smad3的激活、Snail的表达上调以及EMT的进程。更为重要的是，在A549和H1650细胞中，加入JAK2/STAT3特异性抑制剂AG490抑制Stat3磷酸化后，TGF-β1诱导的p-Smad3、Snail、MMP2表达的上调作用减弱并且由Smad调节的PAI-1基因启动子活性也发生下调。在低表达Stat3的细胞株H1299和H460中，TGF-β1不能诱导EMT的发生。随后还揭示了AG490可抑制TGF-β诱导的细胞的迁移和侵袭。此外，外源加入IL-6激活Stat3后，可增强TGF-β诱导的p-Smad3和Snail的表达及EMT进程，同时还可以增强TGF-β1诱导的肺癌细胞的迁移和侵袭。我们的实验结果表明：TGF-β通过调节p-Smad3和Snail的表达诱导的EMT的过程以及癌细胞的迁移和侵袭需要JAK/STAT3信号通路的参与；并且IL-6/JAK/STAT3和TGF-β/Smad信号通路可协同促进肺癌细胞EMT的过程。结果提示通过抑制IL-6/JAK/STAT3和TGF-β/Smad信号可以为抑制肺癌转移提供一个合理、潜在的治疗手段。相关文章发表于International Journal Oncology、Lung Cancer 和 Oncogene 等国际期刊，并标注了资助号(81372277)。同时，基金资助培养了3名研究生。