ABSTRACT: Autophagy, an evolutionarily-conserved intracellular organelle and protein degradation process, may exhibit drastically different effects on cell survival depending on the particular environmental and culturing conditions. Hoechst 33342 (HO), a fluorescent dye widely used for staining DNA, has been reported to induce apoptosis in mammalian cells. Here we showed that, in addition to caspase-independent cell death, HO also induced autophagy in HeLa cells, as evidenced by the accumulation of autophagosomes, LC3 form conversion and LC3 puncta formation in a cell line stably expressing GFP-LC3. HO treatment led to generation of reactive oxygen species (ROS), and inhibition of ROS with N-acetyl-l-cysteine (NAC) abrogated both autophagy and caspase-independent cell death. Finally, autophagy played a protective role against caspase-independent cell death, as cell death induced by HO was enhanced under pharmacological and siRNA-mediated genetic inhibition of autophagy.
Free radical research 02/2012; 46(6):740-9. · 2.22 Impact Factor