最近对临床样本的分析发现去整合素金属蛋白酶12（ADAM12）在小细胞肺癌中表达过高，是癌细胞增殖、侵袭和转移的诊断标志物，其水解功能与肿瘤的发展密切相关。迄今为止对ADAM12水解底物的研究仅限于猜测其可能的底物并进行验证但缺乏系统的研究，从而很难把它的水解功能与肺癌细胞的增殖和转移在分子水平上联系起来。我们在过去几年里建立了两种互补的蛋白质端基标记方法对蛋白质水解进行了高通量鉴定，在肿瘤细胞凋亡过程中发现了凋亡酶的多个新水解底物，找到其水解位点。在本申请中，我们拟通过这两种端基标记方法和定量蛋白质组学技术，对ADAM12在小细胞肺癌中的水解底物进行高通量定量分析，获得其水解底物谱及水解位点；进而通过基因敲低、定点突变水解底物等方法对其功能进行研究；并阐明ADAM12调控肺癌细胞增殖和转移的确切分子机制。这一研究将为小细胞肺癌的治疗提供新的理论依据，并为药物研发提供新的靶点。

It has recently been revealed that A Disintegrin And Metalloproteinase 12 (ADAM12) is highly expressed in samll cell lung cancer （SCLC） cells from patients. ADAM12 can be used as a diagnostic marker for the proliferation, invasion, and metastasis of SCLC cells and its protease acitivity is highly correlated with disease status in cancer. Up to now the identification of its substrates is based on the educated guess and further validation in cells and is lack of systematic investigation. Therefore, it is difficult to connect the protease activity of ADAM12 with the proliferation and metastasis of lung cancer cells at the molecular level. In the past few years, we have developed two robust proteomic approaches that label the N-terminus and C-terminus, respectively, of proteins for the efficient identification of their terminal peptides in a high-throughput manner. In addition, using these approaches, we have identified dozens of new substrates and their cleavage sites in the apoptosis of a cancer cell line. In this application, we will use these two terminal labeling approaches, in combination with quantitative proteomics, to investigate the spectrum of ADAM12 substrates and their cleavage sites in SCLC cell lines. Then we will use genetic knockdown, site-directed mutagenesis of ADAM12 substrates and cleavage sites, and biological approaches to investigate the function of the substrates and their cleavage. We will further elucidate the excat molecular mechanisms by which ADAM12 modulates the proliferation and metastasis of SCLC cells. Through this study, we would like to provide insight in the discovery of molecular pathways and therapeutic targets for the treatment of this cancer.