Objective:To investigate the inhibition effect of down-regulation of small interfering RNA (siRNA) targeting AURKA gene on the proliferation and cell cycle distribution of osteosarcoma cells. Methods:AURKA siRNA was synthesized and transfected into osteosarcoma U2-OS cells via Lipofectamine 2000. Then, the AURKA mRNA and protein expression were examined by real-time fluorescence quantificative PCR (qRT-PCR) and Western blot assay, respectively. CCK8 assay and BrdU cell proliferation assay were performed to evaluate cell viability and proliferation, respectively. Cell cycle distribution was observed by flow cytometry. The expressions of cyclin B1 and cyclin D1 were determined by Western blot assay. Results:Both mRNA and protein levels of AURKA in U2-OS cells transfected with AURKA siRNA were significantly decreased compared with those of the other two groups (both P < 0.05). There were no significant differences in the expressions of AURKA between the two control group. CCK8 assay showed that down-regulated AURKA inhibited cell viability and the inhibition rate reached to the highest level at approximately (36.63 ± 2.38)% after 72 h (P < 0.05). The proportion of S phase cells in the cell cycle was decreased and G2/M phase cells was increased compared with those in the normal control group and negative control group, respectively (both P < 0.05), suggesting the presence of G2/M phase arrest and decreased cell proliferation in S phase (P < 0.05). Meanwhile, the expressions of cyclin D1 and cyclin B1 were significantly down-regulated and elevated (both P < 0.05), respectively. Conclusion:Inhibition of AURKA expression suppressed cell growth and led to G2/M arrest of human osteosarcoma cell line U2-OS.