Autophagic and Apoptotic Response to Sonodynamic Therapy Induced Cell Damage in Leukemia L1210 CellsIn Vitro

Abstract

The present study was initiated to study the autophagic and apoptotic response to sonodynamic therapy (SDT) in murine leukemia L1210 cells in vitro. L1210 cells were examined after 6 hours of incubation following SDT induction with ultrasound at a frequency of 1.1 MHz and an intensity of 3 W/cm(2) in the presence of 1 μg/mL protoporphyrin IX. Apoptosis rate and cell survival rate were assessed through double fluorescent staining with Annexin V-PE and 7-amino-actinomycin D as determined by flow cytometry. Transmission electron microscope and fluorescence microscope were used to identify the formation of acidic vesicular organelles (autophagic vacuoles) during autophagy. Western blots were used to examine the processing of light chain 3 (LC3)-I to LC3-II and Atg5 expression levels. This study showed that SDT treatment reduced the numbers of viable cells to 30.17% and enhanced the apoptotic cells to 19.37% (p < 0.05 compare with control). Additionally, autophagic vacuoles formation clearly occurred after SDT and simultaneously accompanied by obvious LC3 processing and increased Atg5 expression levels. In L1210 cells, both apoptosis and autophagy were involved in cell damage induced by SDT treatment at the experimental conditions.