Downregulation of rho-associated protein kinase 1 by miR-124 in colorectal cancer

AIM: To investigate the roles and interactions of rhoassociated protein kinase (ROCK) 1 and miR-124 in human colorectal cancer (CRC). METHODS: Expression of ROCK1 protein was examined by Western blotting, and quantitative reverse transcriptase PCR was performed to measure expression of ROCK1 mRNA and miR-124. Two cancer cell lines were transfected with pre-miR-124 (mimic) and anti-miR-124 (inhibitor) and the effects on ROCK1 protein and mRNA expression were observed. In addition, cell proliferation was assessed via a 5-ethynyl-2' deoxyuridine assay. Soft agar formation assay, and cell migration and invasion assays were used to determine the effect of survivin on the transformation and invasion activity of CRC cells. RESULTS: miR-124 was significantly downregulated in CRC compared to normal specimens (0.603 +/- 0.092 vs 1.147 +/- 0.286, P = 0.016) and in metastatic compared to nonmetastatic CRC specimens (0.416 +/- 0.047 vs 0.696 +/- 0.089, P = 0.020). Expression of miR-124 was significantly associated with CRC metastasis, tumor T and N stages, and tumor grade (all P < 0.05). ROCK1 protein was significantly increased in CRC compared to normal tissues (1.896 +/- 0.258 vs 0.866 +/- 0.136, P = 0.026), whereas ROCK1 mRNA expression was unaltered (2.613 +/- 0.251 vs 2.325 +/- 0.246). miR-124 and ROCK1 were inversely expressed in CRC tissues and cell lines. ROCK1 mRNA was unaltered in cells transfected with miR-124 mimic and miR-124 inhibitor, compared to normal controls. There was a significant reduction in ROCK1 protein in cells transfected with miR-124 mimic and a significant increase in cells transfected with miR-124 inhibitor (Ps < 0.05). Transformation and invasion of cells transfected with miR-124 inhibitor were significantly increased compared to those in normal controls (P < 0.05). Cells transfected with miR-124 inhibitor showed increased cell proliferation. CONCLUSION: miR-124 promotes hyperplasia and contributes to invasion of CRC cells, but downregulates ROCK1. ROCK1 and miR-124 may play important roles in CRC.