MicroRNA-588 regulates migration capacity and invasiveness of renal cancer cells by targeting EIF5A2.

Abstract

To investigate whether microRNA-588 was involved in the development and progression of renal cancer, and to explore its possible regulatory mechanisms. Tumor tissues excised from renal carcinoma and adjacent normal tissues were selected for the experiment. Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was performed to analyze the expression level of microRNA-588 in tissue specimens. The relationship between the expression of microRNA-588 and the prognosis of patients with renal cell carcinoma was also evaluated. Subsequently, two renal cancer cell lines, including769-P and 786-O, were selected for functional experiments in vitro. Eukaryotic initiation factor 5A2 (pcDNA-EIF5A2) or microRNA-588 mimics was transfected into 769-P cells, respectively. Meanwhile, si-EIF5A2 or microRNA-588 inhibitor was transfected into 786-O cells. After that, the mRNA expression level of EIF5A2 was detected by qRT-PCR. The invasiveness and metastasis abilities of the two cell lines were evaluated via transwell assay. Furthermore, the levels of EIF5A2 and epithelial-mesenchymal transition (EMT)-related proteins were analyzed using Western blot. Luciferase reporter gene assay was used to confirm that microRNA-588 could directly regulate EIF5A2 expression. QRT-PCR and Western blot were performed to explore the mRNA and protein expressions of EIF5A2 in patients with highly or lowly-expressed microRNA-588. The correlation between the two molecules was evaluated using linear analysis. Through the above experiments, it was verified whether microRNA-588 could enhance the invasiveness and metastasis of renal cancer by targeting EIF5A2. MicroRNA-588 expression in tumor tissues of patients with renal carcinoma was significantly decreased with the increase of tumor diameter and stage. A higher level of microRNA-588 indicated significantly longer overall survival of patients. This suggested that microRNA-588 expression was negatively correlated with the prognosis of patients. Overexpression of microRNA-588 remarkably reduced the invasion and metastasis abilities of 769-P cells, as well as the expressions of EMT-related proteins. However, opposite results were observed in 786-O cells after knockdown of microRNA-588. Reporter gene assay confirmed that microRNA-588 could target bind to EIF5A2. In 769-P cells, up-regulated microRNA-588 significantly inhibited the mRNA and protein expressions of EIF5A2. However, down-regulated microRNA-588 in 786-O cells significantly enhanced the expressions of EIF5A2 at both mRNA and protein levels. Linear analysis verified that microRNA-588 was negatively correlated with EIF5A2 at the mRNA level. Additionally, the up-regulation of EIF5A2 in 769-P cells enhanced the malignancy of cancer cells and the expressions of EMT-related proteins. However, in 786-O cells, opposite results were observed after knockdown of EIF5A2. MicroRNA-588 was lowly expressed in renal cancer tissues and cell lines. This might lead to an increase in the protein level of EIF5A2, eventually promoting tumor invasion and metastasis.