Cucurbitacin-I induces hypertrophy in H9c2 cardiomyoblasts through activation of autophagy via MEK/ERK1/2 signaling pathway.

Cucurbitacin-I, a natural triterpenoids initially identified in medicinal plants, shows a potent anticancer effect on a variety of cancer cell types. Nevertheless, the cardiotoxicity of cucurbitacin-I has not heretofore been reported. In this study, the mechanisms of cucurbitacin-I-induced cardiotoxicity were examined by investigating the role of MAPK-autophagy-dependent pathways. After being treated with 0.1-0.3µM cucurbitacin-I for 48h, H9c2 cells showed a gradual decrease in the cell viabilities, a gradual increase in cell size, and mRNA expression of ANP and BNP (cardiac hypertrophic markers). Cucurbitacin-I concentration-dependent apoptosis of H9c2 cells was also observed. The increased apoptosis of H9c2 cells was paralleling with the gradually strong autophagy levels. Furthermore, an autophagy inhibitor, 3-MA, was used to block the cucurbitacin-I-stirred autophagy, and then the hypertrophy and apoptosis induced by 0.3µM cucurbitacin-I were significantly attenuated. In addition, cucurbitacin-I exposure also activated the MAPK signaling pathways, including ERK1/2, JNK, and p38 kinases. Interestingly, only the ERK inhibitor U0126, but not the JNK inhibitor SP600125 and p38 MAPK inhibitor SB203580, weakened the induction of 0.3µM cucurbitacin-I in hypertrophy, autophagy and apoptosis. Our findings suggest that cucurbitacin-I can increase the autophagy levels of H9c2 cells, most likely, through the activation of an ERK-autophagy dependent pathway, which results in the hypertrophy and apoptosis of cardiomyocytes.

Cardiovascular mortality and N-terminal-proBNP reduced after combined selenium and coenzyme Q10 supplementation: a 5-year prospective randomized double-blind placebo-controlled trial among elderly Swedish citizens.

BACKGROUND: Selenium and coenzyme Q10 are essential for the cell. Low cardiac contents of selenium and coenzyme Q10 have been shown in patients with cardiomyopathy, but inconsistent results are published on the effect of supplementation of the two components separately. A vital relationship exists between the two substances to obtain optimal function of the cell. However, reports on combined supplements are lacking. METHODS: A 5-year prospective randomized double-blind placebo-controlled trial among Swedish citizens aged 70 to 88 was performed in 443 participants given combined supplementation of selenium and coenzyme Q10 or a placebo. Clinical examinations, echocardiography and biomarker measurements were performed. Participants were monitored every 6th month throughout the intervention. The cardiac biomarker N-terminal proBNP (NT-proBNP) and echocardiographic changes were monitored and mortalities were registered. End-points of mortality were evaluated by Kaplan-Meier plots and Cox proportional hazard ratios were adjusted for potential confounding factors. Intention-to-treat and per-protocol analyses were applied. RESULTS: During a follow up time of 5.2 years a significant reduction of cardiovascular mortality was found in the active treatment group vs. the placebo group (5.9% vs. 12.6%; P=0.015). NT-proBNP levels were significantly lower in the active group compared with the placebo group (mean values: 214 ng/L vs. 302 ng/L at 48 months; P=0.014). In echocardiography a significant better cardiac function score was found in the active supplementation compared to the placebo group (P=0.03). CONCLUSION: Long-term supplementation of selenium/coenzyme Q10 reduces cardiovascular mortality. The positive effects could also be seen in NT-proBNP levels and on echocardiography.

Carvedilol may alleviate late cardiac remodelling following surgical ventricular restoration.

OBJECTIVE: Surgical ventricular restoration (SVR) can be effective to treat ischaemic cardiomyopathy or left ventricular (LV) aneurysm. However, the initial improvement in LV function does not always last long because of LV remodelling. Beta-blockers prevent LV remodelling of failing hearts; however, their effects following SVR have not been elucidated. Thus, we sought to investigate the effects of a potent beta-blocker, carvedilol, on LV remodelling and function following SVR in rats with myocardial infarction. METHODS: Rats, which developed LV aneurysm 4 weeks after coronary artery ligation, underwent SVR. They were orally administered a vehicle (vehicle group), and low or high dose of carvedilol (20 or 50 mg kg(-1)day(-1) for C20 or C50 group) for 4 weeks following SVR (n=7 in each group). RESULTS: Four weeks following SVR, late cardiac remodelling was alleviated only in the C50 group (LV end-diastolic area: 65+/-4 mm(2) vs 74+/-11 mm(2) and 76+/-11 mm(2) for C50, C20 and vehicle groups; p=0.039 and p=0.013, respectively). There was no difference in LV systolic function (end-systolic elastance) among the three groups; however, LV diastolic functions (LV end-diastolic pressure and the time constant of isovolumic relaxation) were significantly better in the C20 and C50 groups. Histologically, the percentage of myocardial fibrosis in the C50 group (4.1+/-0.2%) was lower than those in the C20 (6.7+/-0.4%, p<0.0001) and vehicle (7.5+/-0.6%, p<0.0001) groups. The mRNA expression of transforming growth factor-beta1 and brain natriuretic peptide in the C50 group were lower than those in the C20 and the vehicle groups. CONCLUSIONS: High-dose carvedilol alleviated LV remodelling and diastolic dysfunction following SVR accompanying with reduction in myocardial fibrosis. Blockade of beta-adrenergic receptor may be a promising adjuvant therapy in patients following SVR.

Molecular regulation of the brain natriuretic peptide gene.

After brain natriuretic peptide (BNP) was isolated in 1988, rapid progress was made in cloning its cDNA and gene, facilitating studies of tissue-specific expression and molecular regulation of gene expression. This review focuses on the molecular determinants of regulation of the rat and human BNP genes, including signaling pathways that impact on changes in gene expression and cis regulatory elements responsive to these signaling pathways. For both rat and human genes, elements in the proximal promoter (-124 to -80), including GATA, MCAT, and AP-1-like, have been shown to contribute to basal and inducible regulation. More distal elements in the human BNP gene respond to calcium signals (an NF-AT site at -927), thyroid hormone (a thyroid-responsive element at -1000), and mechanical stretch (shear stress-responsive elements at -652 and -162). Understanding how BNP is regulated by signaling molecules that are activated in the hypertrophied and ischemic heart should be useful in understanding the underlying pathology. This may lead to therapeutic strategies that prevent hypertrophy while allowing for the beneficial effects of BNP production.

Atrial natriuretic peptide helps prevent late remodeling after left ventricular aneurysm repair.

BACKGROUND: Left ventricular aneurysm repair (LVR) reduces LV wall stress and improves LV function. However, as we reported previously, the initial improvement of LVR was short-term because of LV remodeling but could be maintained longer with postoperative use of an angiotensin-converting enzyme (ACE) inhibitor. Atrial natriuretic peptide (ANP) has been used to treat patients with heart failure by natriuretic and vasodilatory actions. Recent reports have suggested that ANP inhibits the rennin-angiotensin system. In this study, the effects of ANP after LVR were evaluated. METHODS AND RESULTS: Rats that had an LV aneurysm 4 weeks after left anterior descending artery ligation underwent LVR by plicating the LV aneurysm and were randomized into 2 groups: LVR+A group was intravenously administrated with 10 microg/h of carperitide, recombinant alpha-hANP, by osmotic-pump for 4 weeks, and the LVR group was given normal saline. Echocardiography revealed better LV remodeling and function in LVR+A group than in LVR group. Four weeks after LVR, left ventricular end diastolic pressure (LVEDP) and Tau were significantly lower in LVR+A group (LVEDP: 10+/-4 in LVR+A group versus 18+/-6 mm Hg in LVR group, Tau: 13+/-2 versus 17+/-2ms). End-systolic elastance (Ees) was higher in LVR+A group (Ees: 0.34+/-0.2 versus 0.19+/-0.11 mm Hg/microL). The levels of myocardial ACE activity in LVR+A group was significantly lower than in LVR group. The mRNA expressions of brain natriuretic peptide and transforming growth factor beta1 inducing fibrosis significantly decreased in LV myocardium in LVR+A group. Histologically, myocardial fibrosis was significantly reduced in LVR+A group. CONCLUSIONS: Intravenous administration of ANP had beneficial effects on LV remodeling, function, and fibrosis after LVR. ANP could be a useful intravenous infusion drug for postoperative management after LV repair surgery.

Celiprolol, a vasodilatory beta-blocker, inhibits pressure overload-induced cardiac hypertrophy and prevents the transition to heart failure via nitric oxide-dependent mechanisms in mice.

BACKGROUND: The blockade of beta-adrenergic receptors reduces both mortality and morbidity in patients with chronic heart failure, but the cellular mechanism remains unclear. Celiprolol, a selective beta(1)-blocker, was reported to stimulate the expression of endothelial NO synthase (eNOS) in the heart, and NO levels have been demonstrated to be related to myocardial hypertrophy and heart failure. Thus, we aimed to clarify whether celiprolol attenuates both myocardial hypertrophy and heart failure via the NO-signal pathway. METHODS AND RESULTS: In rat neonatal cardiac myocytes, celiprolol inhibited protein synthesis stimulated by either isoproterenol or phenylephrine, which was partially suppressed by N(G)-nitro-L-arginine methyl ester (L-NAME). Four weeks after transverse aortic constriction (TAC) in C57BL/6 male mice, the ratio of heart weight to body weight (mg/g) (8.70+/-0.42 in TAC, 6.61+/-0.44 with celiprolol 100 mg x kg(-1) x d(-1) PO, P<0.01) and the ratio of lung weight to body weight (mg/g) (10.27+/-1.08 in TAC, 7.11+/-0.70 with celiprolol 100 mg x kg(-1) x d(-1) PO, P<0.05) were lower and LV fractional shortening was higher in the celiprolol-treated groups than in the TAC group. All of these improvements were blunted by L-NAME. Celiprolol treatment significantly increased myocardial eNOS and activated phosphorylation of eNOS. Myocardial mRNA levels of natriuretic peptide precursor type B and protein inhibitor of NO synthase, which were increased in the TAC mice, were decreased in the celiprolol-treated mice. CONCLUSIONS: These findings indicated that celiprolol attenuates cardiac myocyte hypertrophy both in vitro and in vivo and halts the process leading from hypertrophy to heart failure. These effects are mediated by a selective beta1-adrenergic receptor blockade and NO-dependent pathway.