Abstract: Objective To investigate the influence of miR-320 on the proliferation and cell cycle progression of human chronic myeloid leukemia (CML) cell line K562. Methods The relative expression levels of miR-320 and β-catenin were detected in the peripheral blood mononuclear cells (PBMCs) isolated from CML patients and normal controls by using quantitative PCR analysis; K562 cells were transfected with miR-320 mimics or mimic controls. The effects of miR-320 overexpression on K562 cell proliferation were examined by CCK-8 analysis. The effects of miR-320 overexpression on K562 cell cycle progression were examined by FACS analysis. The influence of miR-320 on β-catenin expression was determined by dual-luciferase assay and Western blot analysis. The influence of miR-320 on the downstream targets of Wnt/β-catenin was determined by using quantitative PCR analysis. Results The expression of miR-320 was down-regulated in CML patients compared to the normal controls, whereas the expression of β-catenin was up-regulated. Overexpression of miR-320 reduces K562 cell proliferation and inhibits its cell cycle progression. miR-320 could regulate the expression of β-catenin and its downstream target genes， including: c-Myc, cyclin D, VEGF and Cox-2. Conclusions miR-320 acts as a tumor suppressor via regulating Wnt/β-catenin in CML.

Key words: miR-320, β-catenin, chronic myeloid leukemia, K562