Efficacy of 5-aminolevulinic acid–based photodynamic therapy against keloid compromised by downregulation of SIRT1-SIRT3-SOD2-mROS dependent autophagy pathway

Abstract

Keloids exhibit cancer-like properties without spontaneous regression and usually recur post excision. Although photodynamic therapy (PDT) is a promising treatment, details of the mechanisms remain to be elucidated. In this study, we investigated mechanisms involved in 5-Aminolevulinic Acid (5-ALA)–based PDT against keloid. Found that 5-ALA-PDT induced superoxide anion-dependent autophagic cell death. Application of autophagy inhibitor 3-Methyladenine (3-MA) significantly prevented the effect that 5-ALA-PDT induced keloid–derived fibroblasts death, but Z-VAK-FMK (apoptotic inhibitor) did not. Interestingly, 5-ALA-PDT promoted the SIRT3 protein expression and the activity of mitochondrial superoxide dismutase 2 (SOD2), but SIRT1 protein expression level was decreased. SOD2 as a key enzyme can decrease mitochondrial ROS (mROS) level, Deacetylation of SOD2 by SIRT3 regulates SOD2 enzymatic activity has been identified. Then we explored SOD2 acetylation level with immunoprecipitation, found that 5-ALA-PDT significantly increased the acetylation levels of SOD2. In order to confirm deacetylation of SOD2 regulated by SIRT3, 3-TYP (SIRT3 inhibitor) was used. Found that inhibition of SIRT3 by 3-TYP significantly increased the level of SOD2 acetylation level compared with control group or 5-ALA-PDT group. To explore the connection of SIRT1 and SIRT3, cells were treated with EX527(SIRT1 inhibitor) or SRT1720 (SIRT1 activator), and EX527 increased SIRT3 protein level, however, SRT1720 displayed the opposite effect in the present or absence of 5-ALA-PDT. Moreover SIRT1-inhibited cells are more resistant to 5-ALA-PDT and showing decreased ROS accumulation. These results may demonstrate that 5-ALA-PDT induced SIRT1 protein level decreased, which promoted the effect of SIRT3 increased activity of SOD2 that can reduce mROS level, and then compromised 5-ALA-PDT induced autophagic cell death.

Caffeine Targets SIRT3 to Enhance SOD2 Activity in Mitochondria

“…The redox homeostasis in mitochondria is tightly regulated by antioxidant enzymes such as SOD2 and glutathione peroxidase (Lu et al, 2017). It is well established that acetylation of SOD2 plays an important role in regulating its antioxidant activity (Liu et al, 2019). Yeast Sir2 protein and its homolog sirtuins in other prokaryotic and eukaryotic organisms belong to a class of protein deacetylases and ADP ribosylases with a highly conserved NAD + -binding core region (Schwer et al, 2002;Jin et al, 2009;Yi et al, 2019).…”

Dihydromyricetin Improves Endothelial Dysfunction in Diabetic Mice via Oxidative Stress Inhibition in a SIRT3-Dependent Manner

“…Sirtuin 3 (SIRT3) is the main deacetylase in the mitochondria and serves as a critical mediator in metabolic regulation and antioxidant function [ 22 , 23 , 24 , 25 ]. SOD2, as one target protein of SIRT3, is regulated by SIRT3 via acetylation of lysine residues [ 26 , 27 ]. Transgenic mice with global SIRT3 overexpression improved endothelial dysfunction and attenuated vascular oxidative stress, while SIRT3 depletion promoted endothelial dysfunction and exacerbate vascular hypertrophy in hypertension [ 28 ].…”

Maternal Eicosapentaenoic Acid Feeding Decreases Placental Lipid Deposition and Improves the Homeostasis of Oxidative Stress Through a Sirtuin‐1 (SIRT1) Independent Manner

“…Indeed, instead of oxidative stress, SIRT1 deficiency increased placental and fetal T‐SOD activity. A recent study also found that inhibiting SIRT1 increased the activity of SOD2 and reduced mitochondrial ROS production . These findings indicated that the SIRT1/PGC1α path way plays an important role in placental mitochondrial energy metabolism and oxidative stress, thereby potentially affecting nutrient transport from placenta to fetus.…”