The Predominant Pathway of Apoptosis in THP-1 Macrophage-Derived Foam Cells Induced by 5-Aminolevulinic Acid-Mediated Sonodynamic Therapy is the Mitochondria-Caspase Pathway Despite the Participation of Endoplasmic Reticulum Stress

Abstract

Background: In advanced atherosclerosis, chronic endoplasmic reticulum (ER) stress induces foam cells apoptosis and generates inflammatory reactions. Methods: THP-1 macrophage-derived foam cells (FC) were incubated with 1 mM 5-aminolevulinic acid (ALA). After ALA mediated sonodynamic therapy (ALA-SDT), apoptosis of FC was assayed by Annexin V-PI staining. Intracellular reactive oxygen species (ROS) and mitochondrial membrane potential were detected by staining with CellROX® Green Reagent and jc-1. Pretreatment of FC with N-acetylcysteine (NAC), Z-VAD-FMK or 4-phenylbutyrate (4-PBA), mitochondria apoptotic pathway associated proteins and C/EBP-homologous (CHOP) expressions were assayed by wertern blotting. Results: Burst of apoptosis of FC was observed at 5-hour after ALA-SDT with 6-hour incubation of ALA and 0.4 W/cm² ultrasound. After ALA-SDT, intracellular ROS level increased and mitochondrial membrane potential collapsed. Translocations of cytochrome c from mitochondria into cytosol and Bax from cytosol into mitochondria, cleaved caspase 9, cleaved caspase 3, upregulation of CHOP, as well as downregulation of Bcl-2 after ALA-SDT were detected, which could be suppressed by NAC. Activation of mitochondria-caspase pathway could not be inhibited by 4-PBA. Cleaved caspase 9 and caspase 3 as well as apoptosis induced by ALA-SDT could be inhibited by Z-VAD-FMK. Conclusion: The mitochondria-caspase pathway is predominant in the apoptosis of FC induced by ALA-SDT though ER stress participates in.

Activity of phosphatase-sensitive 5-aminolevulinic acid prodrugs in cancer cell lines

“…Our results are generally in agreement with previously reported studies of PpIX subcellular accumulation which demonstrate its dependence on the cell type used for the experiment. 40,50,51 Fluorescence images and the calculation of PCC indicate that PpIX accumulation is dependent on cell type but does not change for ALA-Hex and new 5-ALA derivatives, PSI-ALA-Hex and P-ALA-Hex. Different correlation values between PpIX fluorescence and mitochondria were…”

The efficacy and mechanism of apoptosis induction by hypericin-mediated sonodynamic therapy in THP-1 macrophages

“…Therefore, 0.25 μg/mL HY and 15 minutes of ultrasound exposure were considered to represent the optimal conditions in this experiment for inducing efficient macrophage death in vitro. The 0.25 μg/mL HY concentration was lower than the concentrations of emodin (15 μg/mL), 21 curcumin (15 μg/mL), 1 and ALA (131.1 μg/mL) 14,17,18 required to obtain a similar sonodynamic effect. The present findings clearly indicate that HY is a more efficient sonosensitizer than those employed previously.…”

“…[17][18][19] Most sonosensitizers originate from porphyrin-derivative photosensitizers, such as hematoporphyrin (HP), which also causes tumor cell death when irradiated by ultrasound. However, this class of sonosensitizers has several disadvantages, including high costs and high dosage requirements when used for SDT.…”

“…1,14,17 Furthermore, under hydroxylacetylated curcumin-SDT, increasing ROS levels cause macrophage apoptosis through the caspase pathway. 18 In these studies, different sonosensitizers were shown to accumulate in macrophages and to cause apoptosis when combined with ultrasound in vitro. Because low-intensity ultrasound induces little damage to tissue compared with high-intensity ultrasound, we employed a lower intensity of 0.5 W/cm 2 , rather than the intensity of 2.0 W/cm 2 used in previous in vitro 1,21 studies.…”

“…ALA-SDT could generate ROS changing the VDAC1 channel properties in outer mitochondrial membrane, and then affected ER status to induce the macrophages apoptosis. 41 Wang et al 18 demonstrated that ALA-PpIX mainly accumulated in mitochondria and ER, and mitochondria played the key role in inducing the foam cell apoptosis. HY might partly induce macrophage apoptosis through ER, except mitochondria.…”