RhoGDI2用于肺癌临床预后评估及参与侵袭转移分子机制的研究

RhoGDI2 has been shown to be a metastasis regulator, however, the underlying mechanism, effector targets, and the cognate biological functions of RhoGDI2 are not fully understood in lung cancer. In previous studies, we found that the protein expression of RhoGDI2 was lower in lung cancer tissues than normal lung tissues, a result that, for the first time, points to the direction that RhoGDI2 may interact with the PI3K/Akt pathway. Based on our data, we propose to increase the number of the studied samples with lung cancer from 112 to 300 in order to further verify the clinical value of RhoGDI2 expression in the prognosis of lung cancer. In addition, we will identify the biological function of RhoGDI2 in the invasion and metastasis of lung cancer by in vivo and in vitro experiments and further investigate the key underlying molecular mechanisms involving RhoGDI2 in lung cancer. Finally, we will verify and functionally dissect the potential interactions between RhoGDI2 and the PI3K/Akt pathway. Our study may provide a new target for the diagnosis, prognosis and treatment of the more treatment-refractory form of lung cancer.

RhoGDI2作为肿瘤转移相关因子，其在肺癌转移中的具体的作用机制及其调控机理尚不清楚。前期研究我们发现RhoGDI2在大多数肺癌组织中的表达低于相对应的正常组织，并首次报道肺癌细胞中RhoGDI2与PI3K/Akt信号通路存在密切的内在联系。在此工作基础上，本课题将扩大肺癌的临床标本量，进一步证实RhoGDI2在肺癌患者预后判断中的价值；在肺癌细胞株过表达或沉默RhoGDI2，通过正反两方面的干预，利用体内外实验明确RhoGDI2在肺癌侵袭及转移等恶性生物学特征中的作用，并深入探讨其参与肺癌细胞侵袭转移过程中的可能机制；进一步证实RhoGDI2与PI3K/Akt信号通路之间的调控关系。本项目完成旨在为肺癌的诊断和预后判断，及肿瘤的临床治疗提供新的靶点。

RhoGDI2作为肿瘤转移相关因子，在肺癌侵袭转移中的机制和相关靶基因仍不清楚。本课题组前期研究证实， RhoGDI2蛋白在大多数非小细胞肺癌组织中表达降低，且其表达水平与组织分化和淋巴结转移有相关性；RhoGDI2在肺癌细胞系中都有表达，表达水平不尽相一致。为了进一步获得RhoGDI2参与肺癌侵袭转移的直接证据，我们成功构建RhoGDI2全长基因表达载体，和RhoGDI2特异性的siRNA表达载体，稳定转染肺癌A549细胞系，以观察肺癌细胞行为的变化。发现沉默RhoGDI2的表达能增强肺癌A549细胞的增殖能力和侵袭转移能力。发现RhoGDI2表达下调增强MMP-9活性，同时沉默MMP-9的表达则肺癌A549细胞侵袭转移能力明显下降。利用PI3K/Akt信号通路的抑制剂LY294002进一步证实沉默RhoGDI2促进肺癌侵袭转移的作用，与PI3K/Akt信号通路的活化和MMP-9的表达增强有关。.本课题组又探讨了RhoGDI2在肺癌侵袭转移过程中的上皮间质转化机制。RhoGDI2与Rac1相互作用，通过改变F-actin的表达，使得肺癌A549细胞骨架重排列。通过体内外实验，利用实时定量PCR，Western Blot，免疫荧光和免疫组化等方法，进一步证实RhoGDI2在肺癌侵袭转移过程中的作用，与改变细胞骨架，通过调节EMT过程中关键因子E-cadherin, Slug, Snail and α-SMA的表达而抑制肺癌细胞的侵袭转移过程。上述结果说明，RhoGDI2是一种重要的肺癌侵袭转移相关因子，其表达缺失具有促进肺癌细胞侵袭转移的功能。