Effects of insulin-like growth factor binding protein 7 on cell cycle and proliferation of gastric cancer in vitro and in vivo

Abstract

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 MKN-28 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. Key words: Stomach neoplasms; Insulin-like growth factor binding protein 7, human; Cell line, tumor; Cell prolifertion; Cell cycle; Animal experimentation