Ethoxyquin is a competent radical-trapping antioxidant for preventing ferroptosis in doxorubicin cardiotoxicity

Abstract

Doxorubicin (DOX) is an effective anti-cancer agent for various malignancies. Nevertheless, it has a side effect of cardiotoxicity, referred to as doxorubicin-induced cardiomyopathy (DIC), that is associated with a poorer prognosis. This cardiotoxicity limits the clinical use of DOX as a therapeutic agent for malignancies. Recently, ferroptosis, a form of regulated cell death induced by the accumulation of lipid peroxides, has been recognized as a major pathophysiology of DIC. Ethoxyquin is a lipophilic antioxidant widely used for food preservation and thus may be a potential therapeutic drug for preventing DIC. However, the efficacy of ethoxyquin against ferroptosis and DIC remains to be fully elucidated. Here, we investigated the inhibitory action of ethoxyquin against GPx4-deficient ferroptosis and its therapeutic efficacy against DOX-induced cell death in cultured cardiomyocytes and cardiotoxicity in a murine model of DIC. In cultured cardiomyocytes, ethoxyquin treatment effectively prevented GPx4-deficient ferroptosis. Ethoxyquin also prevented DOX-induced cell death, accompanied by the suppression of malondialdehyde (MDA) and mitochondrial lipid peroxides, which were induced by DOX. Furthermore, ethoxyquin significantly prevented DOX-induced cell death without any suppression of caspase cleavages representing apoptosis. In DIC mice, ethoxyquin treatment ameliorated cardiac impairments, such as contractile dysfunction and myocardial atrophy, and lung congestion. Ethoxyquin also suppressed serum lactate dehydrogenase and creatine kinase activities, decreased the levels of lipid peroxides such as MDA and acrolein, inhibited cardiac fibrosis, and reduced TUNEL-positive cells in the hearts of DIC mice. Collectively, ethoxyquin is a competent antioxidant for preventing ferroptosis in DIC and can be its prospective therapeutic drug.

Doxorubicin causes ferroptosis and cardiotoxicity by intercalating into mitochondrial DNA and disrupting Alas1-dependent heme synthesis

“…To measure cell viability, we used Cell Counting Kit-F (Dojindo, Kumamoto, Japan) and CellTiter-Blue (Promega, Madison, WI, USA) as previously described ( 45 ). For the Cell Counting Kit-F assay, cultured cells were washed with PBS once after DOX treatment, incubated with PBS/calcein AM mix reagent for 20 min, and washed with PBS once.…”

Targeting ferroptosis as a promising therapeutic strategy to treat cardiomyopathy

“…Compounds that alleviate DICM through inhibiting ferroptosis include huaier polysaccharide (22) ( Ma X. et al, 2022 ), LCZ696 (23) ( Liu X. et al, 2022 ), fisetin (24) ( Li D. et al, 2021 ), salidroside (25) ( Chen H. et al, 2022 ), resveratrol (10) ( Yu P. et al, 2022 ), dexazoxane (26) ( Zhang H. et al, 2021 ), melatonin (27) ( Sun et al, 2022 ), EGCG (28) ( He et al, 2021 ), 16d and 16e (29) ( Xu et al, 2022 ), ethoxyquin (30) ( Tadokoro et al, 2022 ), and 7j (31) ( You et al, 2022 ) inhibit DICM through inhibiting ferroptosis ( Table 3 ). 22 is a naturally occurring bioactive macromolecule, found in Huaier fungus and has been shown to exert antitumor and antimetastasis activity ( Tian Y. et al, 2021 ; Gou et al, 2022 ).…”

“…While compounds 16d and 16e (29) ( Xu et al, 2022 ), ethoxyquin (30) ( Tadokoro et al, 2022 ), and resveratrol (10) ( Yu P. et al, 2022 ) functions as inhibitors of LPO to attenuates DICM through inhibiting ferroptosis. 29 is two derivatives of steviol, an ent-kaurene diterpenoid, possesses broad-spectrum bioactivity.…”

“…Ethoxyquin (6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline, 30 is a competent radical-trapping antioxidant. 30 effectively prevented GPX4-deficient ferroptosis in cultured cardiomyocytes, accompanied by the suppression of MDA and mitochondrial lipid peroxides ( Tadokoro et al, 2022 ). 30 ameliorated DICM in vivo through decreasing the levels of lipid peroxides such as MDA and acrolein ( Tadokoro et al, 2022 ).…”

Does Myocardial Atrophy Represent Anti-Arrhythmic Phenotype?

“…It also influenced myocardial responses to acute ischemic stress in rat hearts [ 79 ]. Moreover, ethoxyquin, a competent radical-trapping antioxidant for preventing ferroptosis, ameliorated contractile dysfunction and myocardial atrophy in a murine model of doxorubicin cardiotoxicity [ 155 ]. Ibudilast, a drug approved for clinical use, attenuated doxorubicin-induced cytotoxicity by suppressing the formation of the TRPC3 channel and NADPH oxidase 2 protein complexes [ 156 ].…”