Department of Gastroenterology, Fengxian Hospital, Anhui University of Science and Technology, Shanghai 201499, PR China.
Department of Gastroenterology, Fengxian Hospital, Southern Medical University, Shanghai 201499, PR China; Department of Gastroenterology, Shanghai Sixth People's Hospital (South), Shanghai Jiaotong University, Shanghai 201499, PR China.
Exp Cell Res. 2020 Oct 1;395(1):112177. doi: 10.1016/j.yexcr.2020.112177. Epub 2020 Jul 16.
Nod-like receptor pyrin domain-containing protein 6 (NLRP6) plays a key role in innate immunity, host defense and tumorigenesis. Our previous study has demonstrated the tumor suppressor role of NLRP6 in gastric cancer. In the present study, we explored the interaction protein of NLRP6 by Flag-tagged immunoprecipitation assay and liquid chromatography/mass spectrometry-based proteomics analysis. The 78 kDa glucose-regulated protein (GRP78), a heat shock protein, was identified as an interaction protein of NLRP6. The binding of NLRP6 to GRP78 was through the Pyrin domain, and the substrate binding domain (SBD) domain of GRP78 was responsible for the interaction with NLRP6. NLRP6 overexpression enhanced the polyubiquitination of GRP78 in gastric cancer cells. Overexpression of GRP78 abolished the effects of NLRP6 overexpression in gastric cancer cell proliferation, cell cycle progression, cell apoptosis, migration and Cyclin D1 expression. GRP78 knockdown reversed the effects of NLRP6 knockdown on cell proliferation and cell cycle progression. NLRP6 expression was negatively correlated with GRP78 expression in human gastric tissues. Tumorigenicity assay indicated that GRP78 mediated the functions of NLRP6 on gastric cancer cell growth in vivo. ON-013100, which could inhibit Cyclin D1 expression, was less effective in treating xenografts of gastric cancer cells with higher level of NLRP6 than in those with lower level of NLRP6. In conclusion, our study suggested that NLRP6 exerted inhibitory effects on gastric cancer cell growth by promoting the ubiquitination of GRP78.
核苷酸结合寡聚化结构域样受体热蛋白结构域相关蛋白 6(NLRP6)在先天免疫、宿主防御和肿瘤发生中发挥着关键作用。我们之前的研究表明 NLRP6 在胃癌中具有肿瘤抑制作用。在本研究中,我们通过 Flag 标记免疫沉淀实验和基于液相色谱/质谱的蛋白质组学分析探索了 NLRP6 的相互作用蛋白。78 kDa 葡萄糖调节蛋白(GRP78),一种热休克蛋白,被鉴定为 NLRP6 的相互作用蛋白。NLRP6 与 GRP78 的结合是通过 Pyrin 结构域,而 GRP78 的底物结合结构域(SBD)负责与 NLRP6 相互作用。NLRP6 的过表达增强了胃癌细胞中 GRP78 的多泛素化。GRP78 的过表达消除了 NLRP6 过表达对胃癌细胞增殖、细胞周期进程、细胞凋亡、迁移和 Cyclin D1 表达的影响。GRP78 的敲低逆转了 NLRP6 敲低对细胞增殖和细胞周期进程的影响。NLRP6 的表达与人胃组织中 GRP78 的表达呈负相关。肿瘤发生测定表明,GRP78 介导了 NLRP6 在体内对胃癌细胞生长的作用。ON-013100 可以抑制 Cyclin D1 的表达,但在治疗 NLRP6 水平较高的胃癌细胞异种移植瘤时效果不如在 NLRP6 水平较低的胃癌细胞异种移植瘤时有效。综上所述,我们的研究表明,NLRP6 通过促进 GRP78 的泛素化来抑制胃癌细胞的生长。