Mechanisms Of Leukemia Cell K562 Apoptosis Induced By Ultrasound

This study was a part of the focused ultrasound vitro treatment leukemia system, which was Natural Science Foundation of Yunnan Province (No. 2001C0010R). The mechanisms of K562 apoptosis induced by ultrasound were investigated. Normal mononuclear cells and K562 cells were treated with ultrasound at a frequency of 1. 8 MHz. Apoptosis cells were evaluated by light microscope. Apoptosis rates of K562 cells were tested by in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL) and the expression level of apoptosis associated protein (p53 protein, bcl-2 protein, caspase-3, Fas protein and Fas L protein) were tested by the flow cytometry (FCM) . Typical morphological changes of apoptosis, such as apoptotic body, were found under light microscope. Apoptosis rates (10. 78% and 21. 42% respectively) of K562 cells which were exposed to 10mV×10min at 12h, 24h posttreatment were respectively higher than those (0. 98% and 1. 38% respectively) of cells without treatment (P<0. 001) . Positive rates of p53 protein, caspase-3, Fas protein and Fas L protein (21. 46%, 43. 76%, 32. 20%, 31.62%respectively) of K562 cells which were exposed to 10mV×10min at 24h posttreatment were respectively higher than those (8. 62%, 10. 66%, 9. 36%, 1. 74% respectively) of cells without treatment (P<0. 001), while positive rates of bcl-2 protein(13. 84%)were lower than those (42. 86%) without treatment(P<0. 001). Thus, ultrasound can induce K562 apoptosis in vitro, which may be related to increase of expression of p53 protein, caspase-3, Fas protein and Fas L protein and to reduction of expression of bcl-2 protein.