Toll样受体7在人胃癌细胞株中的表达及其激动剂诱导SGC-7901细胞发生凋亡的实验研究

目的探讨Toll 样受体7（TLR7）在不同人胃癌细胞株中的表达及其激动剂咪喹莫特对SGC-7901 细胞增殖和凋亡的影
响。方法Western blot法检测3种胃癌细胞株（SGC-7901、HGC-27和MKN-28）中TLR7蛋白表达差异，选取高表达TLR7的胃
癌细胞作为主要研究对象；MTT法考察不同浓度咪喹莫特处理TLR7高表达胃癌细胞12~72 h后细胞增殖活性的改变；流式细
胞仪AnnexinV-FITC/PI双染色法观察100 μg/ml咪喹莫特干预12及24 h后细胞早期凋亡比率的改变；透射电镜下观察细胞凋
亡形态学改变；实时定量PCR法分析Bcl-2及Bax mRNA在咪喹莫特作用前后表达差异。结果TLR7蛋白在SGC-7901中表
达水平高于其他两种胃癌细胞，其激动剂咪喹莫特能够明显抑制SGC-7901细胞增殖并且呈现出浓度及时间依赖性；100 μg/ml
咪喹莫特干预24 h 后SGC-7901 细胞早期凋亡比率明显上升，透射电镜下可观察到典型的凋亡形态学改变；咪喹莫特处理后
SGC-7901细胞Bcl-2 mRNA表达呈浓度依赖性下降，Bax mRNA呈浓度依赖性上升。结论TLR7在3种不同分化程度的胃癌
细胞中均有表达，其激动剂咪喹莫特能够明显抑制SGC-7901细胞增殖并诱导其凋亡。

Expression of Toll-like receptor 7 in gastric cancer cell lines and effects of TLR7 agoniston proliferation and apoptosis of SGC-7901 cells in vitro

Objective To investigate the expression of Toll-like receptor 7 (TLR7) in gastric cancer cell lines and the effect of
imiquimod, a TLR7 agonist, on the proliferation and apoptosis of SGC-7901 cells. Methods The protein expression levels of
TLR7 were detected with Western blotting in 3 human gastric cancer cell lines (SGC-7901, HGC-27 and MKN-28). The cell line
expressing the highest TLR7 level was exposed to different doses of imiquimod for 12-72 h and the cell viability was assessed
with MTT assay. The cell apoptosis rate after 100 μg/ml imiquimod treatment for 12 or 24 h was quantified by flow cytometry,
and the ultrastructual changes of the cells were observed under electron microscope. The expression of apoptosis-related genes
Bcl-2 and Bax were analyzed with real-time PCR. Results All the 3 cell lines expressed TLR7, among which SGC-7901 cells
showed the highest expression level. TLR7 agonist imiquimod dose- and time-dependently reduced the viability of SGC-7901
cells. Exposure to 100 μg/ml imiquimod for 24 h resulted in SGC-7901 cell apoptosis as shown by an increased ratio of early
apoptotic cells and significant ultrastructural changes of the cells. Real-time PCR demonstrated that imiquimod treatment for
24 h caused a dose-dependent reduction of Bcl-2 mRNA expression and increment of Bax mRNA expression. Conclusion TLR7
protein is expressed in all the 3 gastric cancer lines and its agonist imiquimod can inhibit cell proliferation and induce
apoptosis in SGC-7901 cells.