Objective      To determine the effect of hydrogen peroxide combined with low-frequency ultrasound exposure on apoptosis in human ovarian cancer A2780/DDP cells.       Methods      The A2780/DDP cells were cultured under the exposure to 0.5 W/cm

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30 s ultrasound wave in present or absent of 10 μmol/L hydrogen peroxide for 24 h. The MTT assay was used to detect the proliferation in A2780/DDP cells after different treatments. The apoptosis was investigated by using flow cytometry analysis

and the cell morpholog

y was observed by Hoechst staining. Western blotting was used to detect the protein levels of caspase-9.       Results      Exposure to 0.5 W/cm

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30 s ultrasound wave or treatment of 10 μmol/L hydrogen peroxide did not induce obvious apoptosis in A2780/DDP cells

However

combination treatment of 10 μmol/L hydrogen peroxide and 0.5 W/cm

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30 s ultrasound exposure induced apoptosis distinctly（P0.05）.       Conclusion      Combination treatment of hydrogen peroxide and ultrasound exposure strongly enhances apoptosis in human ovarian cancer A2780/DDP cells.