Effect of MicroRNA-218 on the viability, apoptosis and invasion of renal cell carcinoma cells under hypoxia by targeted downregulation of CXCR7 expression.

OBJECTIVE: To investigate the effect of microRNA-218 on the viability, apoptosis and invasion of renal cell carcinoma cells under hypoxia by targeted regulation of expression of chemokine receptor 7 (CXCR7).

METHODS: The expression of miR-218 in renal cell carcinoma cell lines under normal and hypoxia conditions, as well in normal renal tubular epithelial cells (HK2) was measured using RT-PCR. MiR-218 mimic and NC were transfected into renal cell carcinoma cell line ACHN using Lipofectamine™ 2000. The expression of miR-218 was analyzed using RT-PCR. The viability, apoptosis, migration and invasion of the transfected cells were assayed using the MTT assay, flow cytometry and transwell assays. The expression of CXCR7 was assayed using RT-PCR and Western blot. Luciferase reporter was used to verify the downstream target of miR-218.

RESULTS: The expression of miR-218 was lower than in renal cell carcinoma cell lines ACHN, 769-p and Caki-1 that in HK-2. The expression of miR-218 in the renal carcinoma cell lines was lower under hypoxia than under normal oxygen conditions. The expression of miR-218 in ACHN cells under normal and hypoxic conditions was significantly increased after transfection with miR-218 mimic. Compared with NC transfected cells under normal oxygen condition, the mimic-transfected cells had reduced viability, migration ability and invasion ability, and increased apoptosis, and mimic transfected-cells under hypoxia had significantly reduced viability, migration ability and invasion ability, and increased apoptosis. Overexpression of miR-218 mimic resulted in significant reduction in the expression of CXCR7 at protein and mRNA levels under normal and hypoxic conditions. Luciferase reporter assay confirmed that CXCR7 is the target protein of miR-218.

CONCLUSION: Up-regulation of miR-218 expression in renal cell carcinoma under hypoxia can result in significant and targeted down-regulation of CXCR7 expression, which could reduce cell viability, migration and invasion ability and induce apoptosis in the cancer cells.