Abstract: [Abstract] Objective: To investigate the effect of down-regulating phosphorylated human epidermal growth factor receptor 2 (HER2) on osteosarcoma cells U2-OS proliferation and metastasis in vitro. Methods: Various concentration of HER2 phosphorylating inhibitor Lapatinib Ditosylate (5,10,20,30,40μmol/L) were adopted to deal with human osteosarcoma cells U2-OS. MTT assay was performed to evaluate the cell proliferation during various time（24, 48, 72 h), and the IC50 value in 24h was calculated. A concentrtion value of 10umol/L below IC50 (IC50=22.15umol/L) was chosen to deal with U2-OS cells. The expression level of phosphorylated HER2 (p-HER2) was measured by western blot; Wound healing and Transwell invasion assay were performed to evaluated the cell migration and invasion abilities. Results: The HER2 phosphorylating inhibitor Lapatinib Ditosylate inhibited U2-OS cell proliferation dramatically, in which the inhibitory effect depend on the medicine concentration and duration. During 24 hours, the p-HER2 level in Lapatinib management group was lower than negative group (deal with PBS), the cell migration rate in Lapatinib management group and nagative group were (32.70±3.00)% and (94.52±4.76)% and the trans-membrane cells in two groups were 37±5/HP（×400）and 85±10/HP(×400), respectively. The differences in two groups were dramatically (P<0.05). Conclusions: Down-regulating p-HER2 in U2-OS could efficiently inhibit the cell proliferation, migration and invasion in vitro. HER2 has the potential to become a molecular target for anti-osteosarcoma metastasis.

Key words: receptor, epidermal growth factor, oxidative phosphorylation, osteosarcoma, cell proliferation, neoplasm invasiveness, lapatinib ditosylate