癌基因AIB1促进肺腺癌转移的作用和分子机制

Lung adenocarcinoma has a poor prognosis with a high tendency of metastasis. AIB1 is an important oncogene which promotes carcinogenesis and tumor progression. In our previous study, amplification and overexpression of AIB1 was firstly found to be associated with lymph node metastasis and poor prognosis in local-regional lung adenocarcinoma. And in our preliminary experiment, we found the expression level of AIB1 in metastatic lung adenocarcinoma was significantly higher than that in local-regional stage. These findings indicate that the abnormal expression of AIB1 may have an important role in the metastasis process of lung adenocarcinoma. However, the underlying molecular mechanism is totally unknown at present. In this study, with the techniques of adenovirus transfection and RNA interference, we will observe the influence of up-regulation and down-regulation of AIB1 to lung adenocarcinoma cell lines in cell migration and invasive capacity in vitro, and in metastatic capacity in vivo. Second, we will screen and verify the downstream genes of AIB1 and identify the molecular mechanism of AIB1 promoting lung adenicarcinoma metastasis with the methods of Real-time PCR Array, Western blot, immunohistochemistry and rescue assay, etc. Finally, immunohistochemistry will be utilized to detect the expression status of AIB1 and its downstream metastasis associated genes in a lung adenocarcinoma tissue microarray, and the clinical prognostic value of which will be analyzed. We aim to provide a new clue to the mechanisms of lung adenocarcinoma metastasis, and serve as evidence that AIB1 may be a new target in the treatment of lung adenocarcinoma.

肺腺癌具有易转移预后差的特点。AIB1是与多种肿瘤发生发展密切相关的癌基因。我们前期研究首次发现AIB1的扩增和过表达与局限期肺腺癌的淋巴结转移和不良预后密切相关；预实验检测AIB1在转移期肺腺癌中的表达水平显著高于局限期，提示AIB1异常表达在肺腺癌转移过程中可能发挥重要作用，但其分子机制目前还不清楚。本项目拟在前期工作基础上，采用基因转染和RNA干扰技术，观察AIB1导入或沉默后对肺腺癌细胞株体外迁移、侵袭和体内转移等生物学行为的影响；应用Real-time PCR芯片、Western blot、免疫组化和基因功能回复实验等方法，筛选和验证AIB1下游的转移相关基因，明确AIB1促进肺腺癌转移的分子机制。免疫组化检测AIB1及其下游基因在大病例肺腺癌组织芯片中的蛋白表达，分析其临床预后价值。本研究旨在为深入了解肺腺癌转移机制提供新线索，为肺腺癌治疗寻找新靶点提供依据。

远处转移是肺腺癌预后差的主要原因之一；我 们前期研究提示AIB1的异常表达在肺腺癌转移过程中可能发挥重要作用，进一步阐明其分子机制十分必要。本研究在前期工作基础上，采用Western blot筛选出AIB1高表达肺腺癌细胞株（H1993，H1975）和AIB1低表达细胞株(A549)。通过慢病毒载体沉默H993和H1975细胞中的AIB1基因，观察到肺腺癌细胞的迁移和侵袭能力受到抑制；通过质粒瞬时转染过表达A549细胞中的AIB1基因，可促进肺腺癌细胞的迁移和侵袭能力。在小鼠尾静脉转移试验中：过表达AIB1基因促进肺腺癌细胞的转移，沉默AIB1基因抑制肺腺癌细胞的转移。常规提取shRNA-AIB1干扰的H1993细胞及其对照组细胞的mRNA样本，进行“肿瘤转移相关基因Real-time PCR芯片”检测，结果显示：沉默AIB1基因导致CXCR4显著下调。我们的研究结果显示：AIB1很可能是通过上调CXCR4促进肺腺癌细胞的转移，具体调控细节值得进一步探索。本研究为深入了解肺腺癌转移机制提供了新线索，为肺腺癌治疗寻找新靶点提供了一些依据。