microRNA (miRNA)-133b has been revealed to be downregulated in head and neck/oral, bladder, human non-small cell lung, colorectal and esophageal squamous cell cancer. The present study examined the expression of miR-133b in renal cell carcinoma (RCC) cell lines and the effects of miRNA-133b on RCC cell proliferation, migration and invasion. Quantitative polymerase chain reaction was used to detect the expression of miR-133b in RCC cell lines. Following transfection of miR-133b, the expression

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... miR-133b was examined and a cell viability assay, cell migration assay, cell invasion assay, western blot analysis and luciferase assay were conducted in RCC cell lines. The present study revealed that miRNA-133b was downregulated and inhibited cell proliferation, migration and invasion in 786-O and A498 cells. In addition, to the best of our knowledge, the present study provided the first evidence that miRNA-133b may directly target matrix metallopeptidase 9 (MMP-9) in RCC. The present study also provided evidence that miRNA-133b suppresses cell proliferation, migration and invasion by targeting MMP-9 in RCC cell lines. These results suggested that miRNA-133b may be used for the development of novel molecular markers and therapeutic approaches to inhibit the metastasis of RCC.