Objective We tried to ascertain gastric cancer cell line MKN-45 contain SP cells, and learned about wether gastric cancer SP cells possess cancer stem-like characteristic. Method We used fluorescence activated cell sorting (FACS) to sort SP cells in human gastric carcinoma (GC) cell line MKN-45 cells labeled with Hoechst 33342, and then characterized the cancer stem-like properties of SP cells. Result The SP cells had higher clone formation efficiency than major population (MP) cells. Five stemness–related genes expression profiles, including OCT-4, SOX-2, NANOG, CD44 and ATP-binding cassette transporters gene ABCG-2, were tested in SP and MP cells using quantitative real-time RT-PCR. Western blot was chosen to show the difference of protein expression between SP and MP cells. Both results showed that there was significantly higher expression in SP cells than in MP cells. When inoculated into non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice, SP cells showed higher tumorigenesis tendency than MP cells. Conclusion SP cells possess cancer stem cell properties and proved that SP cells from MKN-45 were gastric cancer stem-like cells.% 目的探讨胃癌细胞系中是否存在SP细胞及SP细胞的生物学特征。方法采用荧光活化的细胞分选技术(FACS)从胃癌MKN-45细胞株获得SP细胞，进而分析这些SP细胞有无肿瘤干细胞特性；采用实时定量的RT-PCR检测5个干性相关基因OCT-4, SOX-2, NANOG, CD44和ABCG-2的mRNA在SP和MP 细胞中的表达水平，并进行统计学差异分析。结果发现二者之间具有显著差异。进一步使用蛋白印迹法（Western blot）定性分析发现：5个干性相关基因在SP和MP细胞中的蛋白表达水平亦有差异；体内实验结果显示，当SP细胞和MP细胞注射非糖尿病联合重度免疫缺陷（NOD/SCID）的小鼠，SP 细胞较MP细胞具有更强的成瘤性。结论综合分析本实验相关结果，可以推测SP细胞具有肿瘤干细胞特性，由MKN-45分选获得的SP细胞是具有干细胞特性的胃癌干样细胞。SP细胞较主群细胞(MP)具有较高的克隆形成率。
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