RNA结合蛋白QKI在肺癌发生发展中的作用机制研究

Lung cancer is a serious disease endangering human health,and effective prevention and treatment of lung cancer is a tough task faced by the medical researchers. The discover and investigation of new genes related to lung cancer plays a key role in the prevention and treatment of lung cancer. QKI, RNA bingding protein, act as a potential anti-oncogene,but the function of QKI exerted in the pathogenesis and progression of lung cancar is unknown until now. Importantly,our previous studies suggested the expression of QKI was enhanced in normal lung tissues and decreased in lung cancer tissues,which implies that the deregulation of QKI expression probably contributes to the pathogenesis of lung cancer. We also found that QKI could enhance the expression of p27, an important anti-oncogene in lung cancer, which suggested the alteration of QKI expression might participate in the pathogenesis and progression of lung cancer. However, the exact function of QKI in the pathogenesis and progression of lung cancer need further invetstigation.Based on aboved results, we design a study to eluciate QKI might be a tumor suppressor in lung cancer and underlying molecular mechanism.In this study, we first detect the level of QKI expression in lung cancer tissues and observe the effect of QKI on the biological behavior of lung cancer cells.Secondly, because QKI promoter region is rich in CpG islands, we analyzed the methylation level of QKI promoter region in lung cancer tissues.Thirdly, we investigate the regulation mechanism of p27 by QKI by application of 3'UTR luciferase reporter gene expression analysis and RNA-immunoprecipitation. Finally, we investigate whether the regulation of p27 by QKI, in vivo, could impact the proliferation, invasion and metastases of carcinoma cell as well as the neovascularization.

肺癌严重危害人类健康，因此积极有效防治肺癌刻不容缓。肺癌相关新基因的发现及研究对肺癌防治具有重要意义。RNA结合蛋白QKI作为潜在抑癌基因，其与肺癌相关性目前尚不清楚。我们前期研究结果表明，QKI在正常肺组织中高表达，肺癌中低表达，提示QKI与肺癌发生发展具有相关性；同时体外QKI可以调控肺癌重要抑癌基因p27的表达。为进一步明确QKI在肺癌发生发展中的具体作用，本课题拟通过检测肺癌标本中QKI表达水平，观察QKI对肺癌细胞生物学行为的影响，明确QKI与肺癌发生发展的相关性；因QKI启动子富含CpG岛，故通过检测肺癌中QKI启动子甲基化程度，明确QKI表达异常的原因；通过RNA-IP和双荧光素酶报告系统明确QKI与p27的相互作用，阐明QKI调节p27的分子机制；通过裸鼠荷瘤实验体内观察QKI调控p27对肺癌发生发展的影响，为肺癌的诊治提供新思路和策略。

肺癌严重危害人类健康，因此积极有效防治肺癌刻不容缓。肺癌相关新基因的发现及研究对肺癌防治具有重要意义。RNA结合蛋白QKI作为潜在抑癌基因，其与肺癌相关性目前尚不清楚。我们前期研究结果表明，QKI在正常肺组织中高表达，肺癌中低表达，提示QKI与肺癌发生发展具有相关性；同时QKI可以调控肺癌重要抑癌基因p27的表达。然而，QKI在肺癌发生发展中通过哪些分子机制发挥其抑癌基因的作用需深入研究。因此本课题通过检测肺癌标本中QKI表达水平，观察QKI对肺癌细胞生物学行为的影响，明确QKI与肺癌发生发展的相关性；因QKI启动子富含CpG岛，故通过检测肺癌中QKI启动子甲基化程度，明确QKI表达异常的原因；通过RNA-IP和双荧光素酶报告系统明确QKI与p27的相互作用，阐明QKI调节p27的分子机制；通过裸鼠荷瘤实验体内观察QKI调控p27对肺癌发生发展的影响。通过研究发现，QKI在肺癌组织中的低表达与肺癌TNM分期具有相关性，局部晚期及晚期肺癌组织中的QKI低表达较早期肺癌更常见，同时生存分析结果提示QKI低表达的患者生存预后差于QKI表达正常的肺癌患者。通过干预肺癌细胞肿瘤的QKI表达，我们发现高表达QKI的肺癌细胞体外成瘤率降低、细胞粘附性降低、细胞迁移能力降低、肿瘤细胞G1期阻滞增多、肿瘤细胞凋亡增加等，而低表达QKI的肺癌细胞呈现与上相反的结果，提示QKI高表达可以降低肿瘤细胞的生物学活性。通过甲基化检测，我们发现肺癌组织中存在QKI甲基化，提示甲基化可能是导致肺癌组织中QKI低表达的原因。体外构建QKI高表达及低表达肺腺癌、鳞癌细胞系，检测细胞系p27表达情况，结果发现在QKI高表达细胞系中p27表达降低，而在QKI低表达细胞系中p27表达增高，提示QKI表达与p27表达负相关。RNA-IP和双荧光素酶报告系统明确QKI与p27的相互作用实验研究尚未完成。在裸鼠成瘤试验中，我们发现QKI高表达可以有效抑制体外成瘤和移植瘤的生长。通过本实验研究结果，提示QKI在肺癌发生发展中可能发挥抑癌基因的作用，在未来可能作为靶点治疗肺癌。