天冬酰胺合成酶在肺癌转移中的功能及分子机制研究

Metabolic plasticity of amino acids is closely related to tumor metastasis. The role and mechanism of asparagine synthase (ASNS) in metastasis of lung cancer, as a key enzyme for the metabolic plasticity of glutamine and asparagine in lung cancer cells, have not been clarified. We found that lung cancer tissues were rich in asparagine in previous metabonomic studies; clinical specimen analysis and cell function experiments suggested that ASNS was closely related to lung cancer metastasis; molecular mechanism studies revealed that ASNS might up-regulate Snail by activating Wnt/beta-catenin signal, then drive EMT and metastasis of lung cancer cells. This project intends to further clarify the regulatory role of ASNS on lung cancer metastasis and elucidate the mechanism of ASNS in regulating lung cancer metastasis through Wnt/beta-catenin/Snail, at clinical, animal, molecular and cellular levels by means of qRT-PCR, WB, immunohistochemistry, immunofluorescence, confocal imaging, RNA interference, scratch test, Transwell, in vivo metastasis model of lung cancer cells in nude mice, primary lung cancer metastasis model of genetically modified mice, in vivo imaging of small animals and other technical means. Our research will deepen the understanding of the mechanism of lung cancer metastasis and provide new targets for the treatment of lung cancer.

氨基酸代谢可塑性与肿瘤转移密切相关。天冬酰胺合成酶（ASNS）作为肺癌细胞谷氨酰胺与天冬酰胺代谢可塑性转换依赖的关键酶，在肺癌转移中的作用与机制尚未明确。我们在前期研究代谢组学结果中发现肺癌组织富含天冬酰胺；临床标本检测分析与细胞功能实验提示ASNS与肺癌转移密切相关；分子机制研究提示ASNS可能通过激活Wnt/β-catenin信号上调Snail，驱动肺癌细胞EMT与转移。本项目拟采用RT-PCR、WB、免疫组化、免疫荧光、共聚焦成像、RNA干扰、划痕实验、Transwell、裸鼠体内转移模型、基因鼠原发肺癌转移模型、小动物活体成像等技术手段在临床标本、细胞分子生物学功能与机制，及动物模型三个层面进一步明确ASNS对肺癌转移的调控作用；并阐明ASNS通过Wnt/β-catenin/Snail信号通路调控肺癌转移的具体机制。我们的研究将加深对肺癌转移机制的认识，为肺癌的治疗提供新的靶点。

天冬酰胺合成酶（ASNS）是内源性天冬酰胺产物的必需酶，其能限制肿瘤细胞增殖与转移。本研究表明ASNS诱导的天冬酰胺产物对于维持体外肿瘤生长和克隆形成至关重要；但突变的ASNS（失去了代谢功能）仍然上调了细胞的侵袭转移。在机制上，ASNS通过促进GSK3β磷酸化和稳定β-catenin来调节Wnt信号转导，ASNS可以促进更多的β-catenin入核，而不依赖于内源性天冬酰胺。同时，ASNS通过增加线粒体电位和膜融合来调节线粒体对Wnt刺激的反应。本研究从临床、细胞分子生物学、动物模型三个层面明确了ASNS对肺癌转移的调控作用：ASNS可通过调控Wnt信号通路和线粒体功能促进肺癌转移，尤其是淋巴结转移。