Involvement of ferritin heavy chain in the preventive effect of metformin against doxorubicin-induced cardiotoxicity
ABSTRACT Doxorubicin is a wide-spectrum chemotherapeutic agent, although a cumulative dose may cause cardiac damage and lead to heart failure. Doxorubicin cardiotoxicity is dependent on the intracellular iron pool and manifests itself by increasing oxidative stress. Our group has recently shown the ability of metformin, an oral antidiabetic with cardiovascular benefits, to protect cardiomyocytes from doxorubicin-induced damage. This work aimed to study whether metformin is able to modulate the expression of ferritin, the major intracellular iron storage protein, in cardiomyocytes and whether it is involved in their protection. The addition of metformin to adult mouse cardiomyocytes (HL-1 cell line) induced both gene and protein expression of the ferritin heavy chain (FHC) in a time-dependent manner. The silencing of FHC expression with siRNAs inhibited the ability of metformin to protect cardiomyocytes from doxorubicin-induced damage, in terms of the percentage of cell viability, the levels of reactive oxygen species, and the activity of antioxidant enzymes (catalase, glutathione peroxidase, and superoxide dismutase). In addition, metformin induced the activation of NF-κB in HL-1 cells, whereas preincubation with SN50, an inhibitor of NF-κB, blocked the upregulation of the FHC and the protective effect mediated by metformin. Taken together, these results provide new knowledge on the protective actions of metformin against doxorubicin-induced cardiotoxicity by identifying FHC and NF-κB as the major mediators of this beneficial effect.
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ABSTRACT: A substantial minority of type 2 diabetes mellitus (T2DM) patients treated with metformin develop severe gastrointestinal (GI) symptoms leading to drug discontinuation, depriving them of the potentially cardioprotective pleiotropic effects of this first-line oral agent. At present, it is unclear whether treating diabetes without being able to ever use metformin alters cardiovascular outcomes. From a population of 773 consecutive T2DM outpatients, the cardiometabolic phenotypes of 83 patients who discontinued metformin due to GI intolerance (Met-Intol cases) were compared with those of 332 age- and gender-matched metformin-tolerant (Met-Tol) controls, amounting to a case: control ratio of 1:4. Mean age (SD) was 70 (13) (male:female: 46:54). Metformin intolerance was associated with a reduced prevalence of macroangiopathy (P=0.0486), mainly due to a lower prevalence of CAD (-34%; P=0.0374). Met-Intol cases more often belonged to blood group A and subgroup A Rh+, with 50% and 66% relative increases (P=0.0039 and P=0.0005), respectively. There were twice as many non-right-handers among the Met-Intol (18% vs. 9%; P=0.0262), and this group also had significantly higher serum ferritin and LDL cholesterol levels. Statins/fibrates were used by 66%/19% of Met-Tol vs. 48%/18% of Met-Intol (P=0.0051 for statins). On the other hand, there were no differences between groups as regards smoking, diabetes duration, HbA1c, BMI, blood pressure, waist size, fat mass, visceral fat, liver steatosis, the metabolic syndrome, eGFR, albuminuria, erectile dysfunction and microangiopathy. Intolerance to metformin represents an unforeseen phenotype in T2DM patients characterized by a low rate of ischaemic heart disease, left-handedness, ABO group imbalance and an iron load.Diabetes & Metabolism 06/2013; 39(4). DOI:10.1016/j.diabet.2013.05.005 · 2.85 Impact Factor
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ABSTRACT: The efficacy of doxorubicin (DOX) as antitumor agent is greatly limited by the induction of cardiomyopathy, which results from mitochondrial dysfunction and iron-catalyzed oxidative stress in the cardiomyocyte. Metformin (MET) has been seen to have a protective effect against the oxidative stress induced by DOX in cardiomyocyte through its modulation of ferritin heavy chain (FHC), the main iron-storage protein. This study aimed to assess the involvement of FHC as a pivotal molecule in mitochondrial protection offered by MET against DOX cardiotoxicity. The addition of DOX to adult mouse cardiomyocytes (HL-1 cell line) increased cytosolic and mitochondrial free iron pools in a time-dependent manner. Simultaneously, DOX inhibited complex I activity, ATP generation and induced the loss of mitochondrial membrane potential. The mitochondrial dysfunction induced by DOX was associated with the release of cytochrome c to cytosol, the activation of caspase 3 and DNA fragmentation. The loss of iron homeostasis, mitochondrial dysfunction and apoptosis induced by DOX were prevented by treatment with MET 24 hours before the addition of DOX. The involvement of FHC and NF-kB were determined through siRNA-mediated knockdown. Interestingly, the presilencing of FHC or NF-kB with specific siRNAs blocked the protective effect induced by MET against DOX cardiotoxicity. These findings were confirmed in isolated primary neonatal rat cardiomyocytes. In conclusion, these results deepen our knowledge of the protective action of MET against DOX-induced cardiotoxicity and suggest that therapeutic strategies based on FHC modulation could protect cardiomyocytes from the mitochondrial damage induced by DOX by restoring iron homeostasis.Free Radical Biology and Medicine 11/2013; 67. DOI:10.1016/j.freeradbiomed.2013.11.003 · 5.71 Impact Factor
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ABSTRACT: The clinical use of the antitumor anthracycline Doxorubicin is limited by the risk of severe cardiotoxicity. The mechanisms underlying anthracycline-dependent cardiotoxicity are multiple and remain uncompletely understood, but many observations indicate that interactions with cellular iron metabolism are important. Convincing evidence showing that iron plays a role in Doxorubicin cardiotoxicity is provided by the protecting efficacy of iron chelation in patients and experimental models, and studies showing that iron overload exacerbates the cardiotoxic effects of the drug, but the underlying molecular mechanisms remain to be completely characterized. Since anthracyclines generate reactive oxygen species, increased iron-catalyzed formation of free radicals appears an obvious explanation for the aggravating role of iron in Doxorubicin cardiotoxicity, but antioxidants did not offer protection in clinical settings. Moreover, how the interaction between reactive oxygen species and iron damages heart cells exposed to Doxorubicin is still unclear. This review discusses the pathogenic role of the disruption of iron homeostasis in Doxorubicin-mediated cardiotoxicity in the context of current and future pharmacologic approaches to cardioprotection.Frontiers in Pharmacology 02/2014; 5:25. DOI:10.3389/fphar.2014.00025