USP36通过去泛素化修饰COL1A1/COL4A1调控胃癌细胞上皮间质化及侵袭转移的机制研究

肿瘤转移是胃癌患者预后不良的重要原因。我们前期已报道泛素特异性蛋白酶（USPs）家族成员USP3可促进胃癌细胞上皮间质化（EMT）和侵袭转移。本项目将继续探讨USPs家族成员USP36调控胃癌EMT和侵袭转移的具体机制。我们已发现：USP36在胃癌中高表达，促进胃癌EMT及侵袭转移；iTRAQ高通量蛋白组学技术筛选到下游靶蛋白COL1A1及COL4A1；细胞实验示USP36可通过去泛素化修饰胶原蛋白COL1A1和COL4A1，上调细胞外基质（ECM）受体ITGB1的表达，促进胃癌细胞EMT。据此，我们假设：USP36通过去泛素化修饰COL1A1/COL4A1，上调ITGB1表达，形成ECM-受体信号轴，促进胃癌细胞EMT和侵袭转移。本课题拟通过基因截断、基因突变等技术明确USP36参与调控胃癌侵袭转移的具体机制，探讨蛋白质去泛素化修饰在肿瘤转移中的重要作用，为临床提供潜在的诊断、治疗靶点。

Metastasis is one critical reasons responsible for poor prognosis for gastric cancer. We have previously reported that USP3, a member of the ubiquitin-specific proteases (USPs), can promote Epithelial to Mesenchymal Transition (EMT), invasion and metastasis of gastric cancer cells. Herein, we will continue to explore the specific mechanism of another USPs member named USP36 in regulating EMT, invasion and metastasis of gastric cancer. In our preliminary results, it was found that USP36 was highly expressed in gastric cancer and could promote EMT, invasion and metastasis of gastric cancer cells. By employing the high-throughput proteomics technology of iTRAQ, we identified two downstream targets of USP36, i.e., COL1A1 and COL4A1. And the following cytobiological experiments showed that USP36 could upregulate the expression of an extracellular matrix (ECM) receptor ITGB1 by deubiquitinating collagen COL1A1 and COL4A1, resulting EMT in gastric cancer cells. Based on these findings, we hypothesize that USP36 up-regulates the expression of ITGB1 through deubiquitinating COL1A1/COL4A1, forming an ECM-receptor signaling axis and promoting EMT, invasion and metastasis of gastric cancer cells. This project intends to employ appropriate biotechnologies such as gene truncation and gene mutation to uncover the action mechanism of USP36 in regulating the invasion and metastasis of gastric cancer, and to explore the role of protein deubiquitination in tumor metastasis, which could provide potential diagnostic and therapeutic targets for clinical setting.