超氧化物歧化酶2基因在胃癌组织中的表达及其对胃癌细胞生物学行为的影响

Expression of superoxide dismutase 2 in gastric cancer and downregulation of its expression on biological characteristics

目的观察超氧化物歧化酶2（SOD2）在胃癌组织的表达以及沉默SOD2基因对胃癌细胞增殖生长和活性氧产生的影响。方法免疫组织化学染色法检测66例胃癌组织及配对癌旁组织中SOD2蛋白表达；Western blot检测6株胃癌细胞和正常胃黏膜上皮细胞中SOD2蛋白表达及转染小分子干扰RNA siSOD2后胃癌细胞株MKN1、NUGC4中的SOD2表达；用细胞计数试剂盒（CCK-8）实验和细胞活性氧（ROS）检测实验分别检测沉默SOD2基因的两株胃癌细胞株增殖以及ROS产生。结果胃癌组织和配对癌旁组织中SOD2表达阳性率分别为72.7%（48/66）和40.9%（27/66），两者差异有统计学意义（χ^2=13.617，P=0.000）。6株胃癌细胞株的SOD2蛋白表达水平明显高于正常胃黏膜上皮细胞GES1，差异有统计学意义（tMKN1=23.062，PMKN1=0.002；tMKN45=5.648，PMKN45=0.030；tNUGC3=26.613，PNUGC3=0.001；tNUGC4=17.103，PNUGC4=0.003；tAGS=39.475，PAGS=0.001；tN87=37.677，PN87=0.001）。MKN1、NUGC4胃癌细胞沉默SOD2基因72 h和96 h后，增殖能力明显低于阴性对照组（MKN1，t72 h=6.329，P72 h=0.001；t96 h=10.487，P96 h=0.000）、（NUGC4，t72 h=5.551，P72 h=0.003；t96 h=6.304，P96 h=0.001）。同时MKN1、NUGC4胃癌细胞沉默SOD2基因后的ROS水平均显著高于阴性对照组，分别为195.341±10.71、99.439±9.311（t=11.295，P=0.001）和181.561±14.502、97.876±12.867（t=23.476，P=0.000）。结论SOD2在胃癌中高表达，同时沉默SOD2基因表达可以抑制胃癌细胞增殖并且产生过量ROS。

ObjectiveTo examine the superoxide dismutase 2 （SOD2） expression in gastric cancer （GC） and the effect of downregulated SOD2 expression on proliferation and reactive oxygen species （ROS） level of GC cells.MethodsThe SOD2 expression of GC patient tissue and paired adjacent tissue was detected by immunohistochemical staining; The SOD2 expression of normal gastric epithelial cell GES1 and GC cells MKN1, MKN45, NUGC3, NUGC4, AGS, N87 was analyzed by Western blotting; SOD2 siRNA （siSOD2） was transfected into MKN1 and NUGC4 cells to downregulate SOD2 expression and set non-target control siRNA （siNTC） as the negative control; Cell proliferation and cellular ROS were determined using counting kit-8 （CCK-8） assay and cellular ROS detection assay kit.ResultsThe positive percentage of SOD2 expression was 72.7% （48/66） in GC patient tissue and was 40.9% （27/66）in paired adjacent tissue. The difference was statistically significant （χ^2=13.617, P=0.000）. The SOD2 expression of GC cells was higher than that in gastric epithelial cell GES1 （tMKN1=23.062, PMKN1=0.002; tMKN45=5.648, PMKN45=0.030; tNUGC3=26.613, PNUGC3=0.001; tNUGC4=17.103, PNUGC4=0.003; tAGS=39.475, PAGS=0.001; tN87=37.677, PN87=0.001）. The proliferation in GC cells MKN1 and NUGC4 with siSOD2 transfection was lower than that in control groups in 72 h, 96 h （MKN1, t72 h=6.329, P72 h=0.001; t96 h=10.487, P96 h=0.000）, （NUGC4, t72 h=5.551, P72 h=0.003; t96 h=6.304, P96 h=0.001）. The ROS level of siSOD2 and siNTC groups in MKN1 was 195.341±10.71, 99.439±9.311; the ROS level of siSOD2 and siNTC groups in NUGC4 was 181.561±14.502, 97.876±12.867. The ROS level of GC cells with siSOD2 transfection was significantly higher than the control group （MKN1, t=11.295, P=0.001）, （NUGC4, t=23.476, P=0.000）.ConclusionSOD2 expression is highly upregulated in GC patients and GC cells. Downregulation of SOD2 expression can decrease GC cell proliferation and increase cellular ROS.