The statins have been used for 30 years to prevent coronary artery disease and stroke. Their primary mechanism of action is the lowering of serum cholesterol through inhibiting hepatic cholesterol biosynthesis thereby upregulating the hepatic low-density lipoprotein (LDL) receptors and increasing the clearance of LDL-cholesterol. Statins may exert cardiovascular protective effects that are independent of LDL-cholesterol lowering called pleiotropic effects. Because statins inhibit the production of isoprenoid intermediates in the cholesterol biosynthetic pathway, the post-translational prenylation of small GTP-binding proteins such as Rho and Rac, and their downstream effectors such as Rho kinase and nicotinamide adenine dinucleotide phosphate oxidases are also inhibited. In cell culture and animal studies, these effects alter the expression of endothelial nitric oxide synthase, the stability of atherosclerotic plaques, the production of proinflammatory cytokines and reactive oxygen species, the reactivity of platelets, and the development of cardiac hypertrophy and fibrosis. The relative contributions of statin pleiotropy to clinical outcomes, however, remain a matter of debate and are hard to quantify because the degree of isoprenoid inhibition by statins correlates to some extent with the amount of LDL-cholesterol reduction. This review examines some of the currently proposed molecular mechanisms for statin pleiotropy and discusses whether they could have any clinical relevance in cardiovascular disease.

Pleiotropic Effects of Statins on the Cardiovascular System.

Anthracycline chemotherapy maintains a prominent role in treating many forms of cancer. Cardiotoxic side effects limit their dosing and improved cancer outcomes expose the cancer survivor to increased cardiovascular morbidity and mortality. The basic mechanisms of cardiotoxicity may involve direct pathways for reactive oxygen species generation and topoisomerase 2 as well as other indirect pathways. Cardioprotective treatments are few and those that have been examined include renin angiotensin system blockade, beta blockers, or the iron chelator dexrazoxane. New treatments exploiting the ErbB or other novel pro-survival pathways, such as conditioning, are on the cardioprotection horizon. Even in the forthcoming era of targeted cancer therapies, the substantial proportion of today's anthracycline-treated cancer patients may become tomorrow's cardiac patient.

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Anthracycline Chemotherapy and Cardiotoxicity

A decline in energy is common in aging, and the restoration of mitochondrial bioenergetics may offer a common approach for the treatment of numerous age-associated diseases. Cardiolipin is a unique phospholipid that is exclusively expressed on the inner mitochondrial membrane where it plays an important structural role in cristae formation and the organization of the respiratory complexes into supercomplexes for optimal oxidative phosphorylation. The interaction between cardiolipin and cytochrome c determines whether cytochrome c acts as an electron carrier or peroxidase. Cardiolipin peroxidation and depletion have been reported in a variety of pathological conditions associated with energy deficiency, and cardiolipin has been identified as a target for drug development. This review focuses on the discovery and development of the first cardiolipin-protective compound as a therapeutic agent. SS-31 is a member of the Szeto-Schiller (SS) peptides known to selectively target the inner mitochondrial membrane. SS-31 binds selectively to cardiolipin via electrostatic and hydrophobic interactions. By interacting with cardiolipin, SS-31 prevents cardiolipin from converting cytochrome c into a peroxidase while protecting its electron carrying function. As a result, SS-31 protects the structure of mitochondrial cristae and promotes oxidative phosphorylation. SS-31 represents a new class of compounds that can recharge the cellular powerhouse and restore bioenergetics. Extensive animal studies have shown that targeting such a fundamental mechanism can benefit highly complex diseases that share a common pathogenesis of bioenergetics failure. This review summarizes the mechanisms of action and therapeutic potential of SS-31 and provides an update of its clinical development programme.

https://bpspubs.onlinelibrary.wiley.com/doi/pdf/10.1111/bph.12461

First‐in‐class cardiolipin‐protective compound as a therapeutic agent to restore mitochondrial bioenergetics

MicroRNAs regulate the processes that underlie cardiac remodelling after myocardial infarction, including angiogenesis and cardiomyocyte apoptosis and proliferation. In this Review, Boon and Dimmeler summarize the microRNAs that are involved with these postischaemic pathways, and discuss potential therapeutic interventions to enhance cardiac regeneration in patients with acute myocardial infarction.

MicroRNAs in myocardial infarction.

Heart failure is a leading cause of death in industrialized nations especially in an aging population. The recent improvements in cardiac revascularization therapy reduced death rates because of myocardial infarction but steadily increased the number of individuals developing cardiac remodeling and heart failure in the future. Conceptual novel approaches entering the clinics to treat cardiac remodeling and heart failure remain scarce. MicroRNAs emerged as powerful and dynamic modifiers of cardiovascular diseases. In this review, the current approaches using microRNAs as novel diagnostic and therapeutic strategies for cardiac remodeling and heart failure are highlighted. Other gene regulatory mechanisms presented include long (>200 bp) noncoding RNAs that function as an additional regulatory machinery of the genome controlling both transcriptional and post-transcriptional events also in the cardiovascular system.

/pdf/non-coding-rnas-in-cardiac-remodeling-and-heart-failure-1ot0abfon4.pdf

Non-coding RNAs in Cardiac Remodeling and Heart Failure

Aims Free fatty acids induce apoptosis in cardiomyocytes, which is implicated in lipotoxic cardiomyopathy. However, the underlying mechanisms remain not fully understood. MicroRNAs (miRNAs) are non-coding small RNAs that control gene expression at the post-transcriptional level. Dysregulated miRNAs have been shown to be involved in heart diseases. This study was to examine whether miR-195 regulates palmitate-induced cardiomyocyte apoptosis by targeting Sirt1, a known anti-apoptotic protein.

Methods and results In cultured neonatal mouse cardiomyocytes, palmitate up-regulated miR-195 expression, increased reactive oxygen species (ROS) production, and induced apoptosis as determined by up-regulation of caspase-3 activity and DNA fragmentation. Inhibition of miR-195 decreased ROS production and apoptosis in palmitate-stimulated cardiomyocytes. In contrast, a miR-195 mimic enhanced palmitate-induced ROS production and apoptosis. The induction of miR-195 correlated with a reduction in Sirt1 and Bcl-2. We further showed that miR-195 targeted and inhibited Sirt1 expression through two target sites located in the 3′ un-translational region of Sirt1 mRNA. In concordance, inhibition of miR-195 increased Sirt1 protein in cardiomyocytes whereas the miR-195 mimic reduced it. Activation of Sirt1 or overexpression of Bcl-2 inhibited palmitate-induced apoptosis. On the other hand, inhibition of Sirt1 enhanced apoptosis. The inhibitory effect of Sirt1 on apoptosis was associated with a reduction in ROS.

Conclusions This study demonstrates a pro-apoptotic role of miR-195 in cardiomyocytes and identifies Sirt1 as a direct target of miR-195. The effect of miR-195 on apoptosis is mediated through down-regulation of Sirt1 and Bcl-2 and ROS production. Thus, miR-195 may be a new therapeutic target for lipotoxic cardiomyopathy.

MicroRNA-195 promotes palmitate-induced apoptosis in cardiomyocytes by down-regulating Sirt1

Aims Doxorubicin causes damage to the heart, often leading to irreversible cardiomyopathy, which is fatal. Reactive oxygen species (ROS) or oxidative stress is involved in cardiomyocyte death, contributing to doxorubicin-induced cardiotoxicity. This study investigated the role of Rac1, an important subunit of NADPH oxidase, in doxorubicin-induced cardiotoxicity and the underlying mechanisms.

Methods and results In a mouse model of acute doxorubicin-induced cardiotoxicity, cardiomyocyte-specific deletion of Rac1 inhibited NADPH oxidase activation and ROS production, prevented cardiac cell death, and improved myocardial function in Rac1 knockout mice. Therapeutic administration of the specific Rac1 inhibitor NSC23766 achieved similar cardio-protective effects in doxorubicin-stimulated mice. In rat cardiomyoblasts (H9c2 cells) and cultured neonatal mouse cardiomyocytes, Rac1 inhibition attenuated apoptosis as evidenced by decreases in caspase-3 activity and DNA fragmentation in response to doxorubicin, which correlated with a reduction in ROS production and down-regulation of p53 acetylation and histone H2AX phosphorylation. In contrast, overexpression of Rac1 enhanced apoptosis. Doxorubicin also inhibited the activity of classical histone deacetylases (HDAC), which was preserved by Rac1 inhibition and further decreased by Rac1 overexpression. Interestingly, scavenging ROS mitigated apoptosis but did not change HDAC activity and p53 acetylation stimulated by doxorubicin, suggesting both ROS-dependent and -independent pathways are involved in Rac1-mediated cardiotoxicity. Furthermore, the HDAC inhibitor trichostatin A enhanced apoptosis, p53 acetylation and H2AX phosphorylation in doxorubicin-treated cardiomyocytes.

Conclusions Rac1 signalling contributes to doxorubicin-induced cardiotoxicity through both a ROS-dependent mechanism and ROS-independent HDAC/p53 signalling in cardiomyocytes. Thus, inhibition of Rac1 may be a useful therapy for doxorubicin-induced cardiotoxicity.

Rac1 signalling mediates doxorubicin-induced cardiotoxicity through both reactive oxygen species-dependent and -independent pathways

Objectives Doxorubicin causes damage to the heart, often leading to irreversible cardiomyopathy, which is fatal. Reactive oxygen species (ROS) or oxidative stress is involved in cardiomyocyte death, contributing to doxorubicin-induced cardiotoxicity. This study was to investigate the role of Rac1, an important subunit of NADPH oxidase in doxorubicin-induced cardiotoxicity and the underlying mechanisms. Methods The models of doxorubicin-induced cardiotoxicity were created by challenging the mice with 20 mg/kg doxorubicin intraperitoneally. Cardiac function was determined by hemodynamic measurements. Cardiomyocytes apoptosis was assayed by caspase-3 activity assay and DNA fragmentation ELISA. ROS production was measured using DCF-DA molecule probe and NADPH oxidase was measured by an assay kit. We also used a HDAC assay kit to measure HDAC activity of cardiomyocytes. Results In a mouse model of acute doxorubicin-induced cardiotoxicity, cardiomyocyte-specific deletion of Rac1 inhibited NADPH oxidase activation and ROS production, prevented cardiac cell death and improved myocardial function in Rac1 knockout mice. Therapeutic administration of a specific Rac1 inhibitor NSC23766 achieved similar cardioprotective effects of Rac1 inhibition in doxorubicin-stimulated mice. In vitro studies using rat cardiomyoblasts H9c2 cells and neonatal mouse cardiomyocytes demonstrated that Rac1 inhibition attenuated apoptosis as determined by decreases in caspase-3 activity and DNA fragmentation in response to doxorubicin, which correlated with a reduction of ROS production and down-regulation of p53 acetylation and histone H2AX phosphorylation. Doxorubicin also inhibited the activity of classical histone deacetylases (HDAC), which was preserved by Rac1 inhibition. Interestingly, scavenging ROS mitigated apoptosis but did not change HDAC activity and p53 acetylation stimulated by doxorubicin, suggesting both ROS dependent and independent pathways are involved in Rac1-mediated cardiotoxicity. Furthermore, HDAC inhibitor trichostatin A enhanced apoptosis, p53 acetylation and H2AX phosphorylation in doxorubicintreated cardiomyocytes. Conclusions Rac1 signalling contributes to doxorubicin-induced cardiotoxicity through both ROS dependent mechanism and ROS independent HDAC/p53 signalling in cardiomyocytes. Thus, inhibition of Rac1 may be a useful therapy for doxorubicin-induced cardiotoxicity.

https://heart.bmj.com/content/heartjnl/98/Suppl_2/E21.3.full.pdf

Rac1 signalling mediates doxorubicin-induced cardiotoxicity through both reactive oxygen species dependent and independent pathways

Berberine inhibits gluconeogenesis in spontaneous diabetic rats by regulating the AKT/MAPK/NO/cGMP/PKG signaling pathway

Corrigendum to “Generation of a human Charcot-Marie-Tooth disease type 1B (CMT1B) iPSC line, ZJUCHi001-A, with a mutation of c.292C>T in MPZ” [Stem Cell Res. 35C (2019) 101407]

Yanpeng Wang

Papers

MicroRNA-195 promotes palmitate-induced apoptosis in cardiomyocytes by down-regulating Sirt1

Rac1 signalling mediates doxorubicin-induced cardiotoxicity through both reactive oxygen species-dependent and -independent pathways

Rac1 signalling mediates doxorubicin-induced cardiotoxicity through both reactive oxygen species dependent and independent pathways

Berberine inhibits gluconeogenesis in spontaneous diabetic rats by regulating the AKT/MAPK/NO/cGMP/PKG signaling pathway

Corrigendum to “Generation of a human Charcot-Marie-Tooth disease type 1B (CMT1B) iPSC line, ZJUCHi001-A, with a mutation of c.292C>T in MPZ” [Stem Cell Res. 35C (2019) 101407]