Objective: we investigated the biological effects of exogenous S100A6 on osteosarcoma cell line U2OS and explored its possible mechanism. Methods:MTT assay was used to determine S100A6 influence on U2OS cells proliferation and their conce ntration-dependent relationship. The trypan blue exclusion assay was used to observe S100A6 inhibitory effect on U2OS cells proliferation in a time-dependent manner;Hoechst staining was used to determine cell apoptosis;Western blot and immunocytochemical methods to determine expressions of cyto-β-catenin. Results:We found that

on the first three days

OD values in cells subjected to the recombinant protein S100A6(GST-S100A6)with the concentrations of 30

100

300 and 1 000μg/ml respectively were obviously lower than those in the GST group

by 20.5%

23.7%

32.2% and 36.8% accordingly(P <0.05);when protein concentration was 100 μg/ml

cell counting in GST-S100A6 group was similar with GST group in the first two days

while decreased significantly to 59%

46%

48% on the third

fourth

fifth day compared with the GST group (P <0.05);cell apoptosis rates increased by 3.16 fold three days after subjected to GST-S100A6(P <0.01). Average optical density ofβ-catenin in GST-S100A6 group increased by 22.9% compared with the GST group (P <0.01)72h after exposure

using immunocytochemical assay;72 h after treatment with the recombinant adenovirus carrying S100A6 gene (Ad-S100A6)

corrected gray value of intracellular β-catenin was 1.420 4±0.199 9

obviously higher than those in the control group 0.999 6±0.100 0 (P<0.01).Conclusion:Exogenous protein S100A6 could inhibite U2OS cells proliferation

promote apoptosis and then increase intracellularβ-catenin concentration.