BTBD7下调E-钙粘蛋白促进肺癌细胞上皮间质转化的分子机制

Lung cancer poses great threat to human health, and metastasis is the leading cause of lung cancer-associated death. Downregulated expression of E-cadherin (E-cad) followed by epithelial-mesenchymal transition (EMT) is critical for initiation of metastasis in lung cancer. BTBD7, as a novel regulator of E-cad, plays essential roles in the development of embryonic lungs and lung cancer with unknown mechanisms. Our preliminary studies found that expression of BTBD7 correlated with the expression of E-cad and other EMT biomarkers in lung cancer, and that overexpressed BTBD7 indicated higher risk of metastasis. In addition , the expression of BTBD7 in lung cancer cells increased after induction to EMT by TGF-β. Taken together, we propose that BTBD7 may downregulate E-cad and induce EMT in lung cancer, which facilitates metastasis as a result. In this project, we will employ molecular biology, cell biology and targeted proteomics techniques combined with in vitro cell models and animal models to confirm our hypothesis and explore the underlying molecular mechanisms. Meanwhile, we will enlarge clinical samples to determine the relationship between BTBD7 expression and the development of lung cancer. Implementation of this project will systematically clarify the biological functions of BTBD7 in the EMT of lung cancer and its relationship with the development of lung cancer, and it will contribute to provide solid theoretical basis to develop novel targeted drug to block the development of lung cancer.

肺癌严重危害人类健康，转移是其主要致死原因。E-钙粘蛋白（E-cad）下调进而发生上皮间质转化（EMT），是肺癌转移的关键起始步骤。BTBD7是种新发现的可以下调E-cad表达的蛋白，在肺胚胎发育和肺癌发生发展中起重要作用，但具体机制不明。我们前期研究发现BTBD7在肺癌中表达与E-cad和其它EMT标记物相关，而且高表达增加转移风险。此外用TGF-β诱导肺癌细胞EMT时，BTBD7表达也增高。据此我们推测BTBD7可能通过下调E-cad促进EMT，进而介导肺癌转移。为验证此推测并研究其具体分子机制，本项目拟采用分子生物学、细胞生物学和靶向蛋白质组学耦联质谱技术，并结合肺癌体外细胞模型与动物模型进行实验，同时扩大临床样本明确BTBD7与肺癌转移及预后的关系。本课题的实施将有助于阐明BTBD7在肺癌EMT中的生物学功能以及与肺癌发生发展的关系，为研发新型靶向药物阻断肺癌发生发展提供理论基础。

肺癌是发病率和致死率最高的恶性肿瘤，转移是其主要致死原因，而上皮间质转化（EMT）是肿瘤转移的重要原因。研究申请者发现BTBD7在肺癌中的表达显著升高并与发病程度相关，但其具体作用和机制尚不清楚。推测BTBD7在肺癌发展过程中能够下调E-钙粘蛋白并促进EMT的发生，本研究通过分子生物学、细胞生物学，结合肺癌体外细胞模型与动物模型进行实验，同时通过临床样本明确了BTBD7与肺癌转移及预后的关系。研究发现，在临床患者肺癌组织中BTBD7呈高表达趋势，而E-钙粘蛋白（E-cad）的表达下调，同时上EMT相关标志物N-钙粘蛋白、纤连蛋白（FN）、波形蛋白的表达上调。体外细胞实验表明，经TGF-β诱导EMT后的肺癌细胞中BTBD7表达显著高于普通肺癌细胞，同时伴有E-cad明显下调，EMT标志物表达升高。通过过表达BTBD7、沉默BTBD7、药物干预肺癌细胞等实验发现，E-cad的表达与BTBD7的表达呈明显负相关性，而EMT标志物则与BTBD7呈正相关。肺癌细胞的迁移能力也因BTBD7的表达增高而增强。裸鼠成瘤实验结果表明，过表达BTBD7的A549细胞相比空载质粒的A549细胞，成瘤效果更明显，瘤体中BTBD7的表达明显升高，而E-cad的表达则显著降低，EMT标志物表达显著上调。通过以上实验，本课题证明了BTBD7在肺癌发展的过程中主要通过下调E-cad来促进EMT的发生，增加肺癌细胞的转移能力。BTBD7或可作为一个新的治疗靶点用于肺癌的防治

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