Abstract: Objective To investigate the effect of Aurora-B-mediated phosphorylation of nucleophosmin1 (NPM1) protein on the malignant phenotype of osteosarcoma (OS) cells. Methods Bioinformatic prediction was performed to investigate the expression level of NPM1 in sarcoma, and the potential relationship between Aurora-B and NPM1. OS cells (U2-OS and 143B）were transfected with LV/ShAurora-B, NC-LV/ShAurora-B, and co-infected by LV/ShAurora-B+NC LV/NPM1. Transwell invasion, Wound healing and CCK8 assays were performed to evaluate the malignant phenotype of OS cells. Results Bioinformatic prediction showed that NPM1 protein was overexpression in sarcoma tissues, and Aurora-B may mediate phosphorylation of NPM1. The Western blot results revealed that the expression levels of Aurora-B and pNPM1ser125 protein were significantly lower in cells infected with LV/ShAurora-B than those in cells treated with Lv/negative (P＜0.05). Interesting, the expression levels of NPM1 protein in cells infected by LV/ShAurora-B were similar to those in cells infected by NC-LV/ShAurora-B. The invaded cells, migration rate and the proliferation of OS cells were significantly reduced in cells down-regulated Aurora-B than those in negative group (P＜0.05). However, the inhibiting effect was partially restored by up-regulation of NPM1 in OS cells. Conclusion Aurora-B-mediated phosphorylation of NPM1 promotes malignant phenotype of OS cells in vitro.

Key words: osteosarcoma, computational biology, Aurora-B, NPM1, pNPM1ser125, malignant phenotype