miR-221-5p acts as an oncogene and predicts worse survival in patients of renal cell cancer.

•MiR-221-5p is significantly up-regulated in RCC tissues and RCC cell lines.•MiR-221-5p promotes cell proliferation, mobility and inhibits cell apoptosis in 786-O and ACHN cell lines.•The Kaplan-Meier analysis indicated that patients with high expression of miR-221-5p had a significantly poor prognosis.•The Cox regression analyses showed that patients with high expression of miR-221-5p remained to have a shorter overall survival.•MiR-221-5p may not only be an oncogene in RCC cells but also might be an independent prognosis factor of RCC.