The Implication of Low Dose Dimethyl Sulfoxide on Mitochondrial Function and Oxidative Damage in Cultured Cardiac and Cancer Cells

Although numerous studies have demonstrated the biological and multifaceted nature of dimethyl sulfoxide (DMSO) across different in vitro models, the direct effect of “non-toxic” low DMSO doses on cardiac and cancer cells has not been clearly explored. In the present study, H9c2 cardiomyoblasts and MCF-7 breast cancer cells were treated with varying concentrations of DMSO (0.001–3.7%) for 6 days. Here, DMSO doses < 0.5% enhanced the cardiomyoblasts respiratory control ratio and cellular viability relative to the control cells. However, 3.7% DMSO exposure enhanced the rate of apoptosis, which was driven by mitochondrial dysfunction and oxidative stress in the cardiomyoblasts. Additionally, in the cancer cells, DMSO (≥0.009) led to a reduction in the cell’s maximal respiratory capacity and ATP-linked respiration and turnover. As a result, the reduced bioenergetics accelerated ROS production whilst increasing early and late apoptosis in these cells. Surprisingly, 0.001% DMSO exposure led to a significant increase in the cancer cells proliferative activity. The latter, therefore, suggests that the use of DMSO, as a solvent or therapeutic compound, should be applied with caution in the cancer cells. Paradoxically, in the cardiomyoblasts, the application of DMSO (≤0.5%) demonstrated no cytotoxic or overt therapeutic benefits.

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

Background Preconditioning of the heart ameliorates doxorubicin (Dox)-induced cardiotoxicity. We tested whether pretreating cardiomyocytes by mitochondrial-targeted antioxidants, mitoquinone (MitoQ) or SKQ1, would provide better protection against Dox than co-treatment. Methods We investigated the dose-response relationship of MitoQ, SKQ1, and vitamin C on Dox-induced damage on H9c2 cardiomyoblasts when drugs were given concurrently with Dox (e.g., co-treatment) or 24 h prior to Dox (e.g., pretreatment). Moreover, their effects on intracellular and mitochondrial oxidative stress were evaluated by 2,7-dichlorofluorescin diacetate and MitoSOX, respectively. Results Dox (0.5–50 μM, n = 6) dose-dependently reduced cell viability. By contrast, co-treatment of MitoQ (0.05–10 μM, n = 6) and SKQ1 (0.05–10 μM, n = 6), but not vitamin C (1–2000 μM, n = 3), significantly improved cell viability only at intermediate doses (0.5–1 μM). MitoQ (1 μM) and SKQ1 (1 μM) significantly increased cell viability to 1.79 ± 0.12 and 1.59 ± 0.08 relative to Dox alone, respectively (both p < 0.05). Interestingly, when given as pretreatment, only higher doses of MitoQ (2.5 μM, n = 9) and SKQ1 (5 μM, n = 7) showed maximal protection and improved cell viability to 2.19 ± 0.13 and 1.65 ± 0.07 relative to Dox alone, respectively (both p < 0.01), which was better than that of co-treatment. Moreover, the protective effects were attributed to the significant reduction in Dox-induced intracellular and mitochondrial oxidative stress. Conclusion The data suggest that MitoQ and SKQ1, but not vitamin C, mitigated DOX-induced damage. Moreover, MitoQ pretreatment showed significantly higher cardioprotection than its co-treatment and SKQ1, which may be due to its better antioxidant effects.

GLP-1(9-36), a GLP-1 cleavage product, protects against oxidative stress and apoptosis through PI3K/Akt/NOS pathway in H9c2 cardiomyoblasts

GLP-1(7–36), a major active form of GLP-1 hormone, is rapidly cleaved by dipeptidyl peptidase-4 to generate a truncated metabolite, GLP-1(9–36) which has a low affinity for GLP-1 receptor (GLP-1R). GLP-1(7–36) has been shown to have protective effects on cardiovascular system through GLP-1R-dependent way. Nevertheless, the cardioprotective effects of GLP-1(9–36) have not fully understood. The present study investigated the effects of GLP-1(9–36), including its underlying mechanisms against oxidative stress and apoptosis in H9c2 cardiomyoblasts. Here, we reported that GLP-1(9–36) protects H9c2 cardiomyoblasts from hydrogen peroxide (H2O2)-induced oxidative stress by promoting the synthesis of antioxidant enzymes, glutathione peroxidase-1, catalase, and heme oxygenase-1. In addition, treatment with GLP-1(9–36) suppressed H2O2-induced apoptosis by attenuating caspase-3 activity and upregulating proapoptotic proteins, Bcl-2 and Bcl-xL. These protective effects of GLP-1(9–36) are attenuated by blockade of PI3K-mediated Akt phosphorylation and prevention of nitric oxide synthase (NOS)-induced NO production. Collectively, GLP-1(9–36) represents the potential therapeutic target for prevention of oxidative stress and apoptosis in the heart.

The Cardioprotective Mechanism of Phenylaminoethyl Selenides (PAESe) Against Doxorubicin-Induced Cardiotoxicity Involves Frataxin

Doxorubicin (DOX) is an anthracycline cancer chemotherapeutic that exhibits cumulative dose-limiting cardiotoxicity and limits its clinical utility. DOX treatment results in the development of morbid cardiac hypertrophy that progresses to congestive heart failure and death. Recent evidence suggests that during the development of DOX mediated cardiac hypertrophy, mitochondrial energetics are severely compromised, thus priming the cardiomyocyte for failure. To mitigate cumulative dose (5 mg/kg, QIW x 4 weeks with 2 weeks recovery) dependent DOX, mediated cardiac hypertrophy, we applied an orally active selenium based compound termed phenylaminoethyl selenides (PAESe) (QIW 10 mg/kg x 5) to our animal model and observed that PAESe attenuates DOX-mediated cardiac hypertrophy in athymic mice, as observed by MRI analysis. Mechanistically, we demonstrated that DOX impedes the stability of the iron-sulfur cluster biogenesis protein Frataxin (FXN) (0.5 fold), resulting in enhanced mitochondrial free iron accumulation (2.5 fold) and reduced aconitase activity (0.4 fold). Our findings further indicate that PAESe prevented the reduction of FXN levels and the ensuing elevation of mitochondrial free iron levels. PAESe has been shown to have anti-oxidative properties in part, by regeneration of glutathione levels. Therefore, we observed that PAESe can mitigate DOX mediated cardiac hypertrophy by enhancing glutathione activity (0.4 fold) and inhibiting ROS formation (1.8 fold). Lastly, we observed that DOX significantly reduced cellular respiration (basal (5%) and uncoupled (10%)) in H9C2 cardiomyoblasts and that PAESe protects against the DOX-mediated attenuation of cellular respiration. In conclusion, the current study determined the protective mechanism of PAESe against DOX mediated myocardial damage and that FXN is implicitly involved in DOX-mediated cardiotoxicity.

Protective Effect of Two Alkaloids from Hippophae rhamnoides Linn. against Doxorubicin-Induced Toxicity in H9c2 Cardiomyoblasts

Background: Doxorubicin (Dox) is one of the most frequently prescribed anti-cancer drugs. However, clinical application with Dox is limited due to its potentially fatal cumulative cardiotoxicity. N-p-coumaroyl-4-aminobutan-1-ol (alk-A), an organic amide alkaloid and hippophamide (alk-B), a rare pyridoindole alkaloid were successfully obtained by purification and separation of seabuckthorn seed residue in our previous research. This study was undertaken to investigate the protective effect of alk-A and alk-B against Dox-induced embryonic rat cardiac cells (H9c2 cells) apoptosis. Methods: H9c2 cells were treated with Dox (2.5 µM) in the presence of alk-A and alk-B (10, 20, and 40 µM) and incubated for 24 h. Results: It was shown that pretreatment of the H9c2 cells with alk-A and alk-B significantly reduced Dox-induced apoptosis. Alk-A and alk-B both inhibited reactive oxygen species (ROS) production and suppressed cleaved-caspase-3 protein expression and the activation of JNK (Jun N-terminal kinases), as well as increasing ATP levels, favoring mitochondrial mitofusin protein expression, and relieving damage to mitochondrial DNA. Conclusions: These results suggest that alk-A and alk-B can inhibit Dox-induced apoptosis in H9C2 cardiac muscle cells via inhibition of cell apoptosis and improvement of mitochondrial function, while alk-B showed more protection. Alk-B could be a potential candidate agent for protecting against cardiotoxicity in Dox-exposed patients.