DJ-1 promotes proliferation and epithelial-mesenchymal transition of colorectal cancer cells by regulating p53 signaling pathway / 肿瘤

ABSTRACT

Objective: To investigate the effects of up-regulating or silencing DJ-1 gene expression on the apoptosis, migration and invasion of colorectal cancer (CRC), and to explore the possible molecular mechanism. Methods: The expression level of DJ-1 in CRC tissues and cells was detected by immunohistochemistry, Western blotting and real-time fluorescent quantitative PCR, respectively. The SW480 and HCT116 cells were transfected with the recombinant lentiviral vector carrying human DJ-1 gene to obtain DJ-1 overexpressed SW480/OE-DJ-1 and HCT116/OE-DJ-1 cells, while the cells transfected with the empty vector was as the negative control (OE-NC). The SW480 and HCT116 cells were transfected with the recombinant lentiviral vector carrying the specific shRNA targeting DJ-1 gene to generate the SW480/shDJ-1 and HCT116/sh-DJ-1 cells with stable knockdown of DJ-1, while the cells transfected with the empty vector was as the negative control (sh-NC). Subsequently, the expressions of DJ-1 and p53 protein and mRNA were detected by immunohistochemistry and real-time fluorescent quantitative PCR, respectively; and their relationship was analyzed. The expressions of p53 and its downstream apoptosis-related proteins Bax and Bcl-2 in SW480 and HCT116 cells with DJ-1 over-expression or knockdown were detected by Western blotting. The effects of overexpressing and silencing DJ-1 gene expression on the invasion and migration abilities of SW480 and HCT116 cells were detected by Transwell chamber assay. The epithelial-mesenchymal transition (EMT) of CRC cells was induced by transforming growth factor-β1 (TGF-β1), then the expression levels of DJ-1 and EMT-related markers (N-cadherin, β-catenin, vimentin, E-cadherin) were analyzed by Western blotting. Results: DJ-1 was highly expressed in 34 CRC tissues (24/34, 70.59%) (P < 0.001). The overall survival time of the patients with DJ-1 high expression was significantly shorter than that of the patients with DJ-1 low expression (P < 0.001). The high expression of DJ-1 was correlated with TNM stage, tumor location, lymph node metastasis, and degree of differentiation (all P < 0.05). There was a negative correlation between DJ-1 and p53 expressions (r =-0.428, P = 0.015). Silencing DJ-1 increased the expression level of p53 and its downstream apoptotic protein Bax, decreased the expression of anti-apoptotic protein Bcl-2 (all P < 0.05), and decreased the invasion and migration capacities of SW480 and HCT116 cells (both P < 0.01); Conversely, overexpressing DJ-1 decreased the expression level of p53 and Bax, increased the expression of Bcl-2 (all P < 0.05), and increased the invasion and migration capacities of SW480 and HCT116 cells (both P < 0.01). Overexpression of DJ-1 induced by TGF-β1 increased the expressions of N-cadherin, β-catenin and vimentin, and decreased the expression of E-cadherin in the process of EMT (P < 0.05). Conclusion: DJ-1 promotes the apoptosis and invasion of CRC cells by negatively regulating the p53 signaling pathway.