摘要:
目的 利用过表达和干扰技术,观察胰岛素样生长因子结合蛋白7 (IGFBP7)对胃癌细胞增殖和细胞周期,以及对细胞周期素D1和细胞周期素依赖性激酶4(CDK4)表达的影响,构建裸鼠移植瘤模型,观察IGFBP7对胃癌瘤体生长的影响.方法 采用小干扰核糖核酸(siRNA)干扰胃癌细胞株MKN-28中IGFBP7表达,并建立空白对照组和阴性对照组.采用pcDNA3.1-IGFBP7质粒转染SGC-7901细胞,使之过表达IGFBP7并建立相应的空白对照组和空载体组.培养48 h,采用MTT实验和克隆形成实验检测IGFBP7干扰和过表达后胃癌细胞体外增殖情况;流式细胞术检测IGFBP7对细胞周期的影响,蛋白质印迹法检测各组细胞中细胞周期素D1和CDK4.分别用过表达IGFBP7的SGC-7901稳定转染细胞及未转染SGC7901细胞建立裸鼠移植瘤模型,观察20 d内IGFBP7对胃癌移植瘤体生长的影响.采用单因素方差分析、LSD法和独立样本t检验比较组间差异.结果 MTT实验和克隆形成实验发现,与空白和阴性对照组比较,干扰IGFBP7的表达能促进MKN-28细胞的增殖(3.013±0.322、2.903±0.210比4.502±0.356,F=18.31,P=0.002 8),细胞克隆形成增多,G1期细胞减少[(57.29±1.30)%、(52.27±0.90)%比(36.81±0.83)%,F=321.57,P<0.01];与空白对照组和空载体组比较,增加IGFBP7的表达能抑制SGC-7901细胞的增殖(3.142±0.320、3.214±0.226比1.813±0.165,F=22.35,P=0.001 7),细胞克隆形成减少,使细胞周期处于G1期细胞增多[(49.34±1.20)%、(47.42±0.71)%比(57.73±0.73)%,F=109.230,P<0.01)].蛋白质印迹法发现干扰IGFBP7能够增加细胞周期素D1和CDK4的表达,过表达IGFBP7的作用相反(P均<0.01).裸鼠移植瘤模型实验发现过表达IGFBP7组的裸鼠种植瘤的体积与质量均小于对照组[(773.50±113.45) mm3比(1 038.75±101.31)mm3,(786±50) mg比(1 145±85) mg,t=7.799、16.280,P均<0.01].结论 IGFBP7能够影响胃癌细胞的增殖及细胞周期,并影响细胞周期素D1和CDK4的表达,可抑制裸鼠移植瘤的生长.%Objective To investigate the effects of insulin-like growth factor binding protein 7 (IGFBP7) on the proliferation,cell cycle of gastric cancer cell and the expression of cynlin D1,cyclin-dependent kinase(CDK)4,and to observe the effects of IGFBP7 on the growth of gastric tumor xenografts in nude mice.Methods The MKN28 cell line was interfered by small interfere ribonucleic acid (siRNA) (interfered group),and blank control group,negative control group were also set.The overexpression of IGFBP7 in SGC-7901 induced by pcDNA3.1-IGFBP7 plasmid infection (overexpression group),and blank control group,empty vector group were also set.Western blotting were used to observe the interference and over expression of IGFBP7 in the cell lines after 48 h.After IGFBP7 was knockdown or overexpressed,the cell proliferation of gastric cancer cells was detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and colony formation assay.The cell cycle was determined by flow cytometry.Cynlin D1 and CDK4 were examined by Western blotting.Tumor xenografts in nude mice model was established with SGC-7901 cells from overexpressed group and untransfected SGC7901 cells.The effects of IGFBP7 on the growth of gastric cancer was observed within 20 days.Single factor analysis of variance was used,LSD test and independent sample t test were performed to compare the differences between groups.Results Compared with blank control group and negative control group,the proliferation of MKN 28 cells of interfered group increased (3.013±0.322,2.903± 0.210 vs 4.502±0.356,F=18.31,P=0.002 8) with more colony formation,and less cells at G1 stage ((57.29±1.30)%,(52.27±0.90)% vs (36.81±0.83)%,F=321.57),and the differences were statistically significant (all P<0.01).Compared with blank control group and empty vector group,the proliferation of SGC 7901 cells of overexpressed group decreased (3.142±0.320,3.214±0.226 vs 1.813 ±0.165,F=22.35,P=0.001 7) with less colony formation,and more cells at G1 stage ((49.34 ± 1.20)%,(47.42±0.71)% vs (57.73±0.73)%,F=109.230,P<0.01),and the differences were statistically significant (all P<0.05).The results of Western blotting indicated that the expression of cyclin D1 and CDK4 increased after the expression of IGFBP7 was interfered (both P<0.01).The results were opposite in the cells of IGFBP7 overexpressed group (both P<0.01).Twenty days after tumor xenografts model established,the tumor size and mass of overexpressed group was significantly less than that of control group ((773.50±113.45) mm3 vs (1 038.75±101.31) mm3,(786±50) mg vs (1 145± 85) mg,t=7.799,16.280,both P<0.01).Conclusion IGFBP7 could affect the prolifertion and cell cycle of gastric cancer cells,influence the expression of cyclin D1 and CDK4,and inhibit the growth of tumor xenografts in nude mice.