Mitochondrial targeted antioxidants, mitoquinone and SKQ1, not vitamin C, mitigate doxorubicin-induced damage in H9c2 myoblast: pretreatment vs. co-treatment

Figures

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  Fig. 1. Effects of Dox or H2O2 on H9c2 cells when Dox or H2O2 were added to a fresh or 1-day-old medium. The representative pictures of cells (100 X) after Dox or H2O2 incubation are shown in A (scale bar: 50 μm). Dose-dependent effects of Dox or H2O2 on cell viability are shown in B and C, respectively. Unlike H2O2, the effects of Dox were not significantly different when Dox was applied to fresh vs old medium. **p < 0.01 vs non-treated control; ##p < 0.01 vs fresh medium

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  Fig. 2. Effects of Dox or H2O2 on H9c2 cell viability by a calcein staining assay when Dox or H2O2 were added to 1-day-old medium. The representative pictures of stained cells (100 X) after Dox or H2O2 incubation are shown in A (scale bar: 50 μm). Dose-dependent effects of Dox or H2O2 on cell viability are shown in B. Dox or H2O2 dose-dependently reduced cell viability. **p < 0.01 vs non-treated control

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  Fig. 3. The effects of vitamin C, MitoQ, or SKQ1 on cell viability. There was no significant change in cell viability by all the three antioxidants

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  Fig. 4. The effects of vitamin C, MitoQ, or SKQ1 on cell viability against Dox when given as co-treatment. The representative pictures of cells (100 X) after co-treatment are shown in A (scale bar: 50 μm). The effects of different antioxidants on Dox-induced cell damage are illustrated in B. MitoQ and SKQ1, but not vitamin C, significantly increased cell viability in the presence of Dox. *p < 0.05; **p < 0.01 vs Dox

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  Fig. 5. The effects of pretreatment of MitoQ or SKQ1 on Dox-induced cell viability reduction. The representative pictures of cells (100 X) after pretreatment are shown in A (scale bar: 50 μm). The effects of MitoQ and SKQ1 pretreatment on Dox-induced cell damage are illustrated in B. Higher doses of MitoQ or SKQ1 significantly improved cell viability when given as pretreatment. Moreover, MitoQ exerted significantly higher protection than SKQ1. *p < 0.05; **p < 0.01 vs Dox; ##p < 0.01 vs SKQ1

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  Fig. 6. The comparison between pretreatment and co-treatment of MitoQ (A) and SKQ1 (B) on Dox-induced cell damage. Pretreatment and co-treatment of MitoQ and SKQ1 significantly protected cells against Dox by demonstrating higher cell viability. Moreover, pretreatment of MitoQ, not SKQ1, exerted significantly higher protection than co-treatment at higher doses. *p < 0.05; **p < 0.01 vs Dox; ##p < 0.01 vs MitoQ co-treatment

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  Fig. 7. The effects of Dox on intracellular ROS (A) and mitochondrial SO (B) levels. Dox showed dose-dependent increase in intracellular ROS and mitochondrial SO levels. **P < 0.01 vs the non-treated control

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  Fig. 8. Effects of co-treatment or pretreatment of SKQ1 or MitoQ on Dox-induced increase in intracellular ROS levels. Co-treatment (A) and pretreatment (B) of SKQ1 and MitoQ significantly attenuated Dox-induced increase in intracellular ROS levels when compared to Dox alone. Pretreatment (C-D) showed better reduction in intracellular ROS levels than co-treatment only at a higher dose (5 μM). Moreover, MitoQ exerted a significantly higher reduction in intracellular ROS levels than SKQ1. **p < 0.01 vs Dox; #p < 0.05, ##p < 0.01 vs MitoQ or SKQ1, respectively

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  Fig. 9. Effects of co-treatment or pretreatment of SKQ1 or MitoQ on Dox-induced increase in mitochondrial SO levels. Co-treatment (A) or pretreatment (B) of SKQ1 and MitoQ significantly attenuated Dox-induced mitochondrial SO levels. Pretreatment (C-D) showed better reduction in mitochondrial SO levels than co-treatment only at a higher dose (1–5 μM). Moreover, MitoQ exerted better reduction than SKQ1 at most doses. **p < 0.01 vs Dox; #p < 0.05, ##p < 0.01 vs MitoQ or SKQ1, respectively