Objective To explore the effect of puromycin-sensitive aminopeptidase (PSA) on apoptosis induced by beta-amyloid peptides 25-35 (Aβ25-35) in SH-SY5Y cells and PC12 cells.Methods The effect of Aβ25-35 on proliferation of SH-SY5Y cells and PC12 cells was measured using MTT assay.Morphological changes of the cell nuclei induced by Aβ25-35 were observed after staining with Hoechst 33342.PSA-siRNA was transfected into SH-SY5Y cells and recombinant PSA plasmid was transfected into PC12 cells using liposome method.The transfected cells were collected at 24 h after being treated with Aβ25-35.The percentage of apoptosis was determined by flow cytometer.The expressions of PSA and caspase-3 were detected by Western blotting,and caspase-3 activity was measured by microplate reader.Results Aβ25-35 inhibited the growth of SH-SY5Y cells and PC 12 cells.Morphological changes indicated that apoptosis happened after cells were treated with Aβ25-35 for 24 h,as shown by flow cytometer.The apoptotic rate induced by Aβ25-35 was increased by PSA-siRNA in SH-SY5Y cells,the activation of pro-caspase-3 was promoted,and the activity of caspase-3 was enhanced.The apoptotic rate induced by Aβ25-35 was declined by over expression of PSA in PC12 cells,the activation of pro-caspase-3 was inhibited,and the activity of caspase-3 was decreased.Conclusion Aβ25-35 could inhibit growth and induce apoptosis in SH-SY5Y cells and PC12 cells.PSA has protective effect on nerve cells by inhibiting apoptosis induced by Aβ25-35,and this effect may be ascribed to the inhibition ofpro-caspase-3 activation.