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Background: Cardiac kinases play a critical role in the development of heart failure, and represent potential tractable therapeutic targets. However, only a very small fraction of the cardiac kinome has been investigated. To identify novel cardiac kinases involved in heart failure, we used an integrated transcriptomics and bioinformatics analysis and identified Homeodomain-Interacting Protein Kinase 2 (HIPK2) as a novel candidate kinase. The role of HIPK2 in cardiac biology is unknown. Methods: We used the Expression2Kinase algorithm for the screening of kinase targets. To determine the role of HIPK2 in the heart, we generated cardiomyocyte (CM)-specific HIPK2 knockout and heterozygous mice. Heart function was examined by echocardiography, and related cellular and molecular mechanisms were examined. Adeno-associated virus serotype 9 carrying cardiac-specific constitutively active MEK1 (TnT-MEK1-CA) was administrated to rescue cardiac dysfunction in CM-HIPK2 knockout mice. Results: To our knowledge, this is the first study to define the role of HIPK2 in cardiac biology. Using multiple HIPK2 loss-of-function mouse models, we demonstrated that reduction of HIPK2 in CMs leads to cardiac dysfunction, suggesting a causal role in heart failure. It is important to note that cardiac dysfunction in HIPK2 knockout mice developed with advancing age, but not during development. In addition, CM-HIPK2 knockout mice and CM-HIPK2 heterozygous mice exhibited a gene dose-response relationship of CM-HIPK2 on heart function. HIPK2 expression in the heart was significantly reduced in human end-stage ischemic cardiomyopathy in comparison to nonfailing myocardium, suggesting a clinical relevance of HIPK2 in cardiac biology. In vitro studies with neonatal rat ventricular CMscorroborated the in vivo findings. Specifically, adenovirus-mediated overexpression of HIPK2 suppressed the expression of heart failure markers, NPPA and NPPB , at basal condition and abolished phenylephrine-induced pathological gene expression. An array of mechanistic studies revealed impaired extracellular signal-regulated kinase 1/2 signaling in HIPK2-deficient hearts. An in vivo rescue experiment with adeno-associated virus serotype 9 TnT-MEK1-CA nearly abolished the detrimental phenotype of knockout mice, suggesting that impaired extracellular signal-regulated kinase signaling mediated apoptosis as the key factor driving the detrimental phenotype in CM-HIPK2 knockout mice hearts. Conclusions: Taken together, these findings suggest that CM-HIPK2 is required to maintain normal cardiac function via extracellular signal-regulated kinase signaling.

Background— Myocardial infarction–induced remodeling includes chamber dilatation, contractile dysfunction, and fibrosis. Of these, fibrosis is the least understood. After myocardial infarction, activated cardiac fibroblasts deposit extracellular matrix. Current therapies to prevent fibrosis are inadequate, and new molecular targets are needed. Methods and Results— Herein we report that glycogen synthase kinase-3β (GSK-3β) is phosphorylated (inhibited) in fibrotic tissues from ischemic human and mouse heart. Using 2 fibroblast-specific GSK-3β knockout mouse models, we show that deletion of GSK-3β in cardiac fibroblasts leads to fibrogenesis, left ventricular dysfunction, and excessive scarring in the ischemic heart. Deletion of GSK-3β induces a profibrotic myofibroblast phenotype in isolated cardiac fibroblasts, in post–myocardial infarction hearts, and in mouse embryonic fibroblasts deleted for GSK-3β. Mechanistically, GSK-3β inhibits profibrotic transforming growth factor-β1/SMAD-3 signaling via interactions with SMAD-3. Moreover, deletion of GSK-3β resulted in the significant increase of SMAD-3 transcriptional activity. This pathway is central to the pathology because a small-molecule inhibitor of SMAD-3 largely prevented fibrosis and limited left ventricular remodeling. Conclusions— These studies support targeting GSK-3β in myocardial fibrotic disorders and establish critical roles of cardiac fibroblasts in remodeling and ventricular dysfunction.

Background— The molecular pathways that regulate the extent of ischemic injury and post–myocardial infarction (MI) remodeling are not well understood. We recently demonstrated that glycogen synthase kinase-3α (GSK-3α) is critical to the heart's response to pressure overload. However, the role, if any, of GSK-3α in regulating ischemic injury and its consequences is not known. Methods and Results— MI was induced in wild-type (WT) versus GSK-3α (−/−) (KO) littermates by left anterior descending coronary artery ligation. Pre-MI, WT, and KO hearts had comparable chamber dimensions and ventricular function, but as early as 1 week post-MI, KO mice had significantly more left ventricular dilatation and dysfunction than WT mice. KO mice also had increased mortality during the first 10 days post-MI (43% versus 22%; P =0.04), and postmortem examination confirmed cardiac rupture as the cause of most of the deaths. In the mice that survived the first 10 days, left ventricular dilatation and dysfunction remained worse in the KO mice throughout the study (8 weeks). Hypertrophy, fibrosis, and heart failure were all increased in the KO mice. Given the early deaths due to rupture and the significant reduction in left ventricular function evident as early as 1 week post-MI, we examined infarct size following a 48-hour coronary artery ligation and found it to be increased in the KO mice. This was accompanied by increased apoptosis in the border zone of the MI. This increased susceptibility to ischemic injury–induced apoptosis was also seen in cardiomyocytes isolated from the KO mice that were exposed to hypoxia. Finally, Bax translocation to the mitochondria and cytochrome C release into the cytosol were increased in the KO mice. Conclusion— GSK-3α confers resistance to ischemic injury, at least in part, via limiting apoptosis. Loss of GSK-3α promotes ischemic injury, increases risk of cardiac rupture, accentuates post-MI remodeling and left ventricular dysfunction, and increases the progression to heart failure. These findings are in striking contrast to multiple previous reports in which deletion or inhibition of GSK-3β is protective.

Hypertrophic cardiomyopathy (HCM) is a myocardial disorder characterized by left ventricular (LV) hypertrophy without dilatation and without apparent cause (ie, it occurs in the absence of severe hypertension, aortic stenosis, or other cardiac or systemic diseases that might cause LV hypertrophy). Numerous excellent reviews and consensus documents provide a wealth of additional background.1–8 HCM is the leading cause of sudden death in young people and leads to significant disability in survivors. It is caused by mutations in genes that encode components of the sarcomere. Cardiomyocyte and cardiac hypertrophy, myocyte disarray, interstitial and replacement fibrosis, and dysplastic intramyocardial arterioles characterize the pathology of HCM. Clinical manifestations include impaired diastolic function, heart failure, tachyarrhythmia (both atrial and ventricular), and sudden death. At present, there is a lack of understanding of how the mutations in genes encoding sarcomere proteins lead to the phenotypes described above. Current therapeutic approaches have focused on the prevention of sudden death, with implantable cardioverter defibrillator placement in high-risk patients. But medical therapies have largely focused on alleviating symptoms of the disease, not on altering its natural history. The present Working Group of the National Heart, Lung, and Blood Institute brought together clinical, translational, and basic scientists with the overarching goal of identifying novel strategies to prevent the phenotypic expression of disease. Herein, we identify research initiatives that we hope will lead to novel therapeutic approaches for patients with HCM. The epidemiology of HCM suggests that it is present in ≈1 in 500 adults.9 Because of the delay in phenotypic expression of the disease, HCM is not commonly recognized clinically in young children, but when it is, it is much more frequently recognized in males.10 This is likely due to greater penetrance in young males.11,12 HCM is underdiagnosed clinically in blacks and in women, yet …

Cardio-oncology (the cardiovascular care of cancer patients) has developed as a new translational and clinical field based on the expanding repertoire of mechanism-based cancer therapies. Although these therapies have changed the natural course of many cancers, several may also lead to cardiovascular complications. Many new anticancer drugs approved over the past decade are “targeted” kinase inhibitors that interfere with intracellular signaling contributing to tumor progression. Unexpected cardiovascular and cardiometabolic effects of patient treatment with these inhibitors have provided unique insights into the role of kinases in human cardiovascular biology. Today, an ever-expanding number of cancer therapies targeting novel kinases and other specific cellular and metabolic pathways are being developed and tested in oncology clinical trials. Some of these drugs may affect the cardiovascular system in detrimental ways and others perhaps in beneficial ways. We propose that the numerous ongoing oncology clinical trials are an opportunity for closer collaboration between cardiologists and oncologists to study the cardiovascular and cardiometabolic changes caused by the modulation of these pathways in patients. In this regard, cardio-oncology represents an opportunity and a novel platform for basic and translational investigation and can serve as a potential avenue for optimization of anticancer therapies and for cardiovascular research and drug discovery.

Protein kinases are enzymes that covalently modify proteins by attaching phosphate groups (from ATP) to serine, threonine, and/or tyrosine residues. In so doing, the functional properties of the protein kinase’s substrates are modified. Protein kinases transduce signals from the cell membrane into the interior of the cell. Such signals include not only those arising from ligand-receptor interactions but also environmental perturbations such as when the membrane undergoes mechanical deformation (ie, cell stretch or shear stress). Ultimately, the activation of signaling pathways that use protein kinases often culminates in the reprogramming of gene expression through the direct regulation of transcription factors or through the regulation of mRNA stability or protein translation. Protein kinases regulate most aspects of normal cellular function. The pathophysiological dysfunction of protein kinase signaling pathways underlies the molecular basis of many cancers and of several manifestations of cardiovascular disease, such as hypertrophy and other types of left ventricular remodeling, ischemia/reperfusion injury, angiogenesis, and atherogenesis. Given their roles in such a wide variety of disease states, protein kinases are rapidly becoming extremely attractive targets for drug discovery, probably second only to heterotrimeric G protein-coupled receptors (eg, angiotensin II). Here, we will review the reasons for this explosion in interest in inhibitors of protein kinases and will describe the process of identifying novel drugs directed against kinases. We will specifically focus on disease states for which drug development has proceeded to the point of clinical or advanced preclinical studies.

Doxorubicin (DOXO) is an effective anthracycline chemotherapeutic, but its use is limited by cumulative dose-dependent cardiotoxicity. Neuregulin-1β is an ErbB receptor family ligand that is effective against DOXO-induced cardiomyopathy in experimental models but is also proneoplastic. We previously showed that an engineered bivalent neuregulin-1β (NN) has reduced proneoplastic potential in comparison with the epidermal growth factor-like domain of neuregulin-1β (NRG), an effect mediated by receptor biasing toward ErbB3 homotypic interactions uncommonly formed by native neuregulin-1β. Here, we hypothesized that a newly formulated, covalent NN would be cardioprotective with reduced proneoplastic effects in comparison with NRG.NN was expressed as a maltose-binding protein fusion in Escherichia coli. As established previously, NN stimulated antineoplastic or cytostatic signaling and phenotype in cancer cells, whereas NRG stimulated proneoplastic signaling and phenotype. In neonatal rat cardiomyocytes, NN and NRG induced similar downstream signaling. NN, like NRG, attenuated the double-stranded DNA breaks associated with DOXO exposure in neonatal rat cardiomyocytes and human cardiomyocytes derived from induced pluripotent stem cells. NN treatment significantly attenuated DOXO-induced decrease in fractional shortening as measured by blinded echocardiography in mice in a chronic cardiomyopathy model (57.7±0.6% versus 50.9±2.6%, P=0.004), whereas native NRG had no significant effect (49.4±3.7% versus 50.9±2.6%, P=0.813).NN is a cardioprotective agent that promotes cardiomyocyte survival and improves cardiac function in DOXO-induced cardiotoxicity. Given the reduced proneoplastic potential of NN versus NRG, NN has translational potential for cardioprotection in patients with cancer receiving anthracyclines.

BACKGROUND It was the purpose of this study to determine the effects of the combination of aspirin (ASA) and fish oil, which is rich in n-3 polyunsaturated fatty acids, on the eicosanoid profile of patients with coronary artery disease. Specifically, we wanted to determine whether the ASA-induced reduction in prostacyclin production is due to inhibition of endothelial cell cyclooxygenase or to reduced endoperoxide shift from platelets and whether ASA negates the potentially beneficial effects of fish oil on the eicosanoid profile. METHODS AND RESULTS Fourteen patients with clinically stable but advanced coronary artery disease received 12 g (n = 8) or 16 g (n = 6) of fish oil concentrate containing 6 or 8 g of n-3 fatty acids for 6 weeks. In addition to the fish oil, patients received increasing daily doses of ASA (50 mg, 100 mg, 325 mg, and 1,300 mg; the latter in four divided doses). Each dose was taken for 2 weeks. With fish oil supplementation, red blood cell phospholipid fatty acid content of arachidonic acid (AA) decreased and of eicosapentaenoic acid (EPA) increased so that EPA as a percent of AA increased from 2% to 26%. Serum thromboxane B2, which represents the production of TXA2 by maximally stimulated platelets, was suppressed by 38% on fish oil alone and by 97% or greater on all doses of ASA. Excretion of PGI2-M, the main urinary metabolite of PGI2 (derived from AA), fell from 50 +/- 4 ng/g of creatinine to 42 +/- 2 ng/g on fish oil alone (p = 0.02). On 50 mg of ASA per day, PGI2-M excretion was 26 +/- 2 ng/g of creatinine (p less than 0.001 versus fish oil alone). On 100 mg and 325 mg of ASA per day, PGI2-M was 24 +/- 3 ng/g and 27 +/- 3 ng/g, respectively (p V NS versus value on 50 mg per day). PGI3-M, the main urinary metabolite of PGI3 (derived from EPA), increased from 0.2 +/- 0.1 ng/g of creatinine to 4.9 +/- 0.7 ng/g on fish oil alone (p less than 0.001). In contrast with the marked ASA-induced decline in PGI2-M, PGI3-M excretion was not affected by the addition of ASA, even at the higher doses (4.6 +/- 0.7 ng/g and 4.9 +/- 0.5 ng/g on 325 mg per day and 325 mg four times daily, respectively). CONCLUSIONS Moderate-dose (325 mg per day or less) ASA taken once daily has no effect on PGI3 production despite significantly reducing PGI2 production. This suggests that endothelial cell cyclooxygenase is minimally inhibited by such doses of ASA and that a large percent of the PGI2 produced in patients with advanced coronary artery disease derives from the transfer of prostaglandin endoperoxides from activated platelets to endothelial cells. The loss of these substrates accounts for the decrease in PGI2 with moderate-dose ASA. Thus, the ASA-induced decrease in PGI2 may in large part be an unavoidable consequence of ASA-induced platelet cyclooxygenase inhibition. ASA does not negate the potentially beneficial effects of n-3 fatty acids on the eicosanoid profile.

Treatment of patients with cancer has changed radically over the last several years with the advent of “targeted therapeutics.” Whereas traditional chemotherapy was directed at all rapidly dividing cells, whether cancerous or not, today’s anticancer drugs are increasingly tailored to the specific genetics of each cancer. This targeted approach, predominantly via inhibition of tyrosine kinase activity, has markedly improved the management of cancers including chronic myeloid leukemia (CML), breast cancer, gastrointestinal stromal tumor (GIST), renal cell carcinoma (RCC), and colon carcinoma.1–5 Inhibitors of tyrosine kinases are of 2 classes: monoclonal antibodies (mAbs), typically targeting growth factor receptor tyrosine kinases, and small molecules, referred to as tyrosine kinase inhibitors (TKIs), targeting both receptor and nonreceptor tyrosine kinases. The goal of targeted therapy is to improve antitumor activity with fewer toxic side effects than traditional anticancer therapies; given the initial success of this approach, the number of targeted therapy drugs entering into development in the last 5 years has increased dramatically.6,7 However, several recent studies have revealed unanticipated side effects of targeted therapy, including left ventricular (LV) dysfunction and heart failure, the primary manifestations of cardiotoxicity we will be examining here.5,8,9 Herein, we will examine the potential risk of LV dysfunction of targeted therapy and the molecular mechanisms that underlie that risk. We will review the importance of tyrosine kinase signaling pathways both for oncogenesis and for the survival of normal cardiomyocytes. To understand basic mechanisms of cardiomyopathy of TKIs, it is critical to understand 2 general classes of toxicity. The first is “on-target” toxicity, wherein the tyrosine kinase target regulating cancer cell survival and/or proliferation (and therefore a good target in cancer therapy) also serves an important role in normal cardiomyocyte survival, and thus inhibition leads to myocardial dysfunction. “Off-target” toxicity occurs when a TKI leads to toxicity …

Tyrosine kinase inhibitors (TKI) have revolutionized cancer therapy, spawning over 500 clinical trials, yet cardiotoxicities are emerging. Sunitinib, a multi-targeted TKI, prolongs life in renal cell and gastrointestinal cancer patients, but hypertension and heart failure have required treatment adjustments. Objective: Sunitinib cardiotoxicity may be due, in part, to direct effects on smooth muscle and cardiac myocytes. Methods: We used C57Bl/6J mice, rat neonatal cardiomyocytes (NCM), and human coronary artery smooth muscle cells (SMC) treated with Sunitinib to measure drug-induced cardiovascular toxicity. Structural (transmission electron microscopy, immunohistochemistry (IHC)/confocal microscopy) and functional [apoptosis/survival, nitric oxide synthesis (intracellular and extracellular), signaling] effects were assessed [real-time PCR, Western blotting, receptor phosphorylation (immunoprecipitation/Western blotting)]. Results: We show mitochondrial injury in hearts from Sunitinib treated mice which persisted off of the drug. In vitro , Sunitinib accumulated in myocytes, caused myofibrillar disorganization, mitochondrial injury, and localized to the lysosomes. Sunitinib caused reductions in akt, MAPK, and AMPK signaling, and activated pro-apoptotic caspase-9 in NCM and SMC with similar effects in large and small vessel endothelial cells. In hearts of Sunitinib-treated mice, we found similar changes in signaling pathways. Conclusion: Sunitinib causes direct cardiac myocyte and smooth muscle cell toxicities, which may contribute to the cardiovascular side effects seen in patients. Further understanding of these mechanisms will guide monitoring, intervention and future rational drug design.

Gregory Bock, Jamie Goode, eds 291 pages. Chichester, UK: John Wiley & Sons Ltd; 2006. $145.00. ISBN: 0–470–01597–7. The statistics of the staggering and ever-increasing burden of heart failure worldwide do not need to be fully repeated. Suffice it to say that in the United States alone, there are 5 million patients with congestive heart failure and another 500 000 new cases every year. Despite this, progress in treatment of the complex collection of disorders leading to congestive heart failure has been slow and generally incremental since the landmark trials of the last decades established angiotensin converting enzyme inhibitors and β-adrenergic receptor antagonists as standard therapies. Even with these therapies, prognosis is poor, and it has become increasingly clear that novel approaches to treatment are desperately needed. Heart Failure: Molecules, Mechanisms and Therapeutic Targets consists of the proceedings of a Novartis Foundation symposium held in April 2005 in England. It was organized by Eric Olson and chaired by Seigo …

Background —Left ventricular failure is commonly preceded by a period of hypertrophy. Intriguingly, many of the signaling pathways that have been implicated in the regulation of hypertrophy, including the 3 mitogen-activated protein kinases (MAPKs: extracellular signal-regulated kinase, stress-activated protein kinase, and p38), protein phosphatase, calcineurin, and the protein kinase Akt and its target glycogen synthase kinase-3 (GSK-3), also regulate the apoptotic response. Methods and Results —To understand the mechanisms that might regulate the progression of heart failure, we analyzed the activity of these signaling pathways in the hearts of patients with advanced heart failure, patients with compensated cardiac hypertrophy, and normal subjects. In patients with hypertrophy, neither the MAPK nor the Akt/GSK-3 pathways were activated, and the dominant signaling pathway was calcineurin. In failing hearts, calcineurin activity was increased but less so than in the hypertrophied hearts, and all 3 MAPKs and Akt were activated (and, accordingly, GSK-3β was inhibited), irrespective of whether the underlying diagnosis was ischemic or idiopathic cardiomyopathy. Conclusions —In the failing heart, there is a clear prohypertrophic activity profile, likely occurring in response to increased systolic wall stress and neurohormonal mediators. However, with the activation of these hypertrophic pathways, potent proapoptotic and antiapoptotic signals may also be generated. Therapies directed at altering the balance of activity of these signaling pathways could potentially alter the progression of heart failure.

BACKGROUND Vasomotor reactivity may contribute to the pathophysiology of ischemic injury. The atherosclerotic vessel may be particularly susceptible to vasoconstriction because of the damaged endothelial layer with resultant loss of vasodilatory factors. While dietary omega 3 fatty acids have been proposed to protect against vascular occlusion, it is not clear to what extent this results from alterations in the function of platelets or from changes intrinsic to the blood vessel itself. METHODS AND RESULTS The effects of dietary supplementation with fish oils on vascular contractility were examined in endothelialized and de-endothelialized aortic rings under pre- and postanoxic conditions. De-endothelialization was defined functionally by the loss of acetylcholine-induced vasodilation in norepinephrine-preconstricted aortic rings from rats fed normal rat chow. Three groups of rats were fed diets containing either 20% menhaden oil or 20% beef tallow, both supplemented with 3% corn oil or 23% corn oil for longer than 4 weeks. All animals received vitamin E. Under well-oxygenated conditions, de-endothelialized aortic rings from rats fed fish oil and corn oil contracted to similar extents with norepinephrine and vasopressin and less than rings from rats fed beef tallow. Endothelialized (intact) and de-endothelialized rings from rats fed fish oil relaxed more in response to acetylcholine than rings from rats fed beef tallow and corn oil. After anoxic exposure and reoxygenation, KCl-induced contraction of intact rings from rats fed fish oil and corn oil was similar and less than rings from rats fed beef tallow. Intact and de-endothelialized rings from rats fed fish oil relaxed more to acetylcholine than did rings from rats fed beef tallow and corn oil. CONCLUSIONS Under preanoxic or postanoxic conditions, rings from rats fed fish oil and corn oil contracted less than rings from rats fed beef tallow. The relaxation response to acetylcholine, however, was greater in rings from rats fed fish oil than from rats fed either corn oil or beef tallow. These vascular effects of fish oil feeding may result in increased blood flow to ischemic and reperfused tissues in vivo.

Studies in animals with acutely ischemic hearts have suggested that postextrasystolic potentiation (PESP) may predict the viability of dysfunctional myocardium. Most of these data have been obtained with sonomicrometers and therefore the presence and extent of PESP throughout the entire region at risk has not been defined. In this study we used contrast two-dimensional echocardiography (2DE) to define region at risk in vivo, and then with quantitative 2DE we examined the proportion of the region at risk that demonstrated PESP, the degree of the potentiation, and the time course of this response. The region at risk was divided into a central (inner 50%) and two peripheral (25% each) ischemic zones. Adjacent contrast-enhanced myocardium was divided into near and far border zones that were equal in size to the adjacent peripheral ischemic zone. Systolic thickening was analyzed within each zone along multiple radii at 5, 30, and 120 min after coronary occlusion. PESP was absent in the central ischemic zone at all three times. In the peripheral ischemic zone at 5 min, a small amount of PESP was detected (-4.1% vs + 3.1% for nonpotentiated and potentiated thickening, respectively; p less than .01). At 30 min after occlusion, no potentiation was seen in the region at risk and PESP was confined to the contrast-enhanced near and far border zones. These findings persisted at 120 min. These data indicate that the response to PESP is localized to perfused myocardium by 30 min after acute occlusion. PESP is therefore of limited value in predicting the presence of ischemic, potentially viable myocardium early in the course of acute infarction.