过表达白鳍鲨硒结合蛋白1对HL-7702细胞镉胁迫的解毒作用

硒结合蛋白1（Selenium—binding protein 1，SBP1）与肿瘤相关，并可以与重金属镉直接结合。该研究构建了白鳍鲨SBP1重组质粒Myc-SBP1并转染人HL-702细胞，利用CCK-8和CFDASE检测Cd胁迫下的细胞增殖情况，利用流式细胞仪检测细胞内ROS的水平。结果显示，过表达白鳍鲨sBP1可拮抗cd对HL-7702细胞的毒害作用。在100μmol／L的CdCl2应激下，表达SBP1组存活率为76．4％。约为对照组存活率的2倍，实验组的细胞增殖指教和分裂能力也略高于对照组。一级结构分析表明，白鳍鲨SBP1具有两个CXXC区域，为抗氧化位点，具有2个HxD和3个HXXH保守区域，它们为推测的Cd结合位点，为在HL-7702细胞中表达白鳍鲨SBP1蛋白能拮抗Cd的结构基础。此外，ROS检测实验表明白鳍鲨SBP1蛋白能显著降低胞内ROS水平，提示硒结合蛋白除通过直接与Cd结合降低毒性外，降低重金属引起的氧化胁迫也可能发挥一定解毒作用。

The Detoxification Effect of Overexpressed Shark SBP1 on HL-7702 Cells under Cadmium Stress

Selenium-binding protein 1 （SBP1） is involved in tumorigenesis and has the ability to bind the heavy metal cadmium. In this study, recombinant plasmid of white tip shark SBP 1 was constructed and transfected into HL-7702 cells. CCK-8 and CFDA SE were used to detect cell proliferation under Cd stress; flow cytometry was used to analyze intracellular ROS levels. Under 100μmol/L of CdC12 stress, the cell viability of expression SBP1 group was 76.4%, which was approximately 2-fold of the control group; meanwhile, the cell proliferation index of experimental group was also higher than that of control group. Furthermore, we speculated that the reason for shark SBP1 expression efficiently helps to detoxify Cd for HL-7702 cells was based on the 2 CXXC, 2 HXD and 3 HXXH motifs of it, which is speculated antioxidation and metal binding sites respectively. In addition, asignificantly low intracellular ROS levels was detected for HL-7702 cells after shark SBP1 was expressed, which suggested that reducing oxidative stress induced by heavy metal may also play a role for the detoxification of Cd.