RESUMEN
Objective: To investigate the expression level of dickkopf 2 (DKK2) gene in human bladder cancer cell lines and tissues, and the effects of DKK2 overexpression on proliferation and migration of bladder cancer cells, and to explore the possible mechanism. Methods: The relative expression levels of DKK2 mRNA and protein in human bladder cancer cell lines and tissues were detected by RT-PCR, real-time fluorescent quantitative PCR and Western blotting, respectively. The bladder cancer T24 cells with low expression of endogenous DKK2 gene were transfected with DKK2 overexpression plasmids, the expression levels of DKK2 mRNA and protein were measured by RT-PCR, real-time flu orescent quantitative PCR and Western blotting, respectively. Then the proliferation, colony formation, migration, invasion and cell cycle were detected by CCK-8, plate clone formation assay, scratch wound healing assay, Transwell assay and FCM assay, respectively. Furthermore, the expressions of proliferation-and migration-related molecules in T24 cells after DKK2 overexpression were detected by real-time fluorescent quantitative PCR and Western blotting, respectively. Results: The expressions of DKK2 mRNA and protein were downregulated in human bladder cancer 5637, T24, SW780, J82, HT-1 1 97 and HT-1 376 cells as compared with the normal bladder SV-HUC-1 cells (all P < 0.01), and those in human bladder cancer tissues were also downregulated as compared with the normal bladder tissues and paired para-cancerous tissues (all P < 0.001). After transfection with DKK2 overexpression plasmids, the expression levels of DKK2 mRNA and protein were increased, the proliferation, colony formation, migration and invasion of bladder cancer T24 cells were inhibited (all P < 0.05), and the cell cycle was arrested in G0/G1 phase (P < 0.001). Furthermore, the mRNA and protein expressions of p21 and E-cadherin were significantly upregulated (both P < 0.001), and the expressions of cyclin D1, vimentin and N-cadherin were downregulated in T24 cells with DKK2 overexpression (all P < 0.001). Conclusion: DKK2 gene is low-expressed in human bladder cancer cells and tissues, and it may be a potential tumor suppressor gene involved in the progression of human bladder cancer.