Apoptosis of THP-1 macrophage-derived foam cells induced by 5-aminolevulinic acid-mediated sonodynamic therapy is mitochondria-caspase pathway predominant despite the participation of endoplasmic reticulum stress

Content Provider	Semantic Scholar
Author	Zhi-Ping, Lu Sheng-Hu, He
Copyright Year	2014
Abstract	Objectives: In advanced atherosclerosis, chronic endoplasmic reticulum (ER) stress induces foam cells apoptosis and generates inflammatory reactions. Sonodynamic therapy (SDT) is a non-thermal synergistic method for cancer treatment utilizing low-intensity ultrasound and sonosensitizers. 5-Aminolaevulinic acid (ALA) is the biological precursor of sonosensitizer PpIX in the heme biosynthesis pathway in mitochondria. In this study, we investigated the sub-cellular location of ALA-PpIX in THP-1 macrophage-derived foam cells (FC) and the activation of mitochondria pathway and ER stress induced by ALA-SDT. Methods: FC were incubated with 1 mMALA. Fluorescence spectrometer was used to detect the location and metabolism of ALA-PpIX in mitochondria and endoplasmic reticulum (ER) of FC. Annexin V-PI staining was used to optimize ALA-SDT treatment parameters by detecting the apoptotic and necrotic rates of FC induced by ALA-SDT with different ALA incubation time and ultrasonic irradiation intensities. Intracellular reactive oxygen species (ROS) level after ALA-SDT was detected by staining with CellROX Green Reagent. Mitochondrial membrane potential after ALA-SDT was detected by staining with JC-1. Pretreated with ROS inhibitor N-acetylcysteine (NAC), pan-caspase inhibitor Z-VAD-FMK and ER stress inhibitor 4-phenylbutyrate (4-PBA), expressions of mitochondria apoptosis associated proteins cytochromc c, cleaved caspase3, cleaved caspase9, Bcl-2, BAX and ER stress associated protein C/EBP-homologous protein (CHOP) in FC after ALA-SDT were detected by Western blotting. Results: Accumulation of ALA-PpIX in mitochondria and ER reached peak at 6-hour, and the fluorescence intensity in mitochondria was triple of that in ER. The highest percentage of apoptotic cells (63.6% 9.8%) and the maximum apoptosis/necrosis ratio (21.7 6.3) was observed at 5-hour after ALA-SDT with 6-hour incubation of ALA and 0.4 W/cm ultrasound intensity. After ALA-SDT, intracellular ROS level increased and the mitochondrial membrane potential collapsed. The translocations of cytochrome c from mitochondria into cytosol and Bax from cytosol into mitochondria, cleaved caspase 9, cleaved caspase 3, downregulation of Bcl-2, as well as upregulation of CHOP were detected at 5-hour after ALA-SDT, which could be suppressed by NAC. Activation of mitochondria apoptosis pathway could not be inhibited by 4-PBA. Apoptosis induced by ALA-SDT could be inhibited by Z-VAD-FMK. 4-PBA reduced FC apoposis by one third. Conclusions: Mitochondria-caspase pathway is predominant in the apoptosis of FC induced by ALA-SDT though ER stress participates in.
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Language	English
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Resource Type	Article