Mechanism of tumor suppressor gene DKK2 inhibiting proliferation of nephroblastoma cells in children / 实用肿瘤学杂志

ABSTRACT

Objective The aims of this study were to investigate the expression of DKK2,a WNT signaling pathway regula-tor,in nephroblastoma cells and tissues of children,the effect on the proliferation of nephroblastoma SK-NEP-1 cells,and to explore its mechanism. Methods The relative expression of DKK2 in nephroblastoma cells and tissues was analyzed by qRT-PCR and im-munoblotting assays. Overexpressing DKK2 SK-NEP-1 cells were set as the experimental group( DKK2 group);the blank control plasmid group was set as a control group( Vector group),transfected with pcDNA3. 1 ( +) -Flag-DKK2 plasmid( Experimental group)and pcDNA3. 1( +) -Flag-Vector plasmid(Control group). The over-expression of DKK2 was confirmed in SK-NEP-1 cells by RT-PCR and immunoblotting. CCK-8 and cell cloning assays were used to determine the effect of DKK2 on cell prolifera-tion;flow cell cycle and apoptosis assays were used to confirm the effect on cell proliferation in overexpressed DKK2 cells. The xen-graft formation assay in nude mice was to verify the effect of DKK2 on proliferation in overexpressed DKK2 cells;the mechanism of DKK2 in inhibitory proliferation was analyzed by qRT-PCR,Western blotting and immunohistochemistry. Results Compared with normal renal epithelial tissues,DKK2 mRNA was down-regulated in children with nephroblastoma,and the difference was statistically significant(P<0. 001). Compared with the control group,transfected DKK2 cell viability was significantly inhibited after treatment for 24,48 and 72 h( P<0. 05),cell clone formation in the experimental group was significantly inhibited(31. 11% ± 2. 14% ) ( P<0. 05),the cell cycle in the experimental group was significantly arrested at the G1 phase(P<0. 001),and the apoptosis rate in the experimental group was significantly increased(P<0. 001). Compared with the control group,the tumor weight and volume in nude mice were significantly low in the experimental mice which were injected DKK2 overexpression cells(P<0. 001). Active-β-cate-nin and downstream genes were significantly inhibited in over-expressed DKK2 SK-NEP-1 cells. Conclusion DKK2 is down-regulated in human cutaneous nephroblastoma and participates in the mechanism of nephroblastoma by antagonizing Wnt/β-catenin signaling pathway.