Nitroxyl (HNO) exerts inotropic and lusitropic effects in myocardium, in part via activation of SERCA (sarcoplasmic reticulum calcium ATPase). To elucidate the molecular mechanism, adult rat ventricular myocytes were exposed to HNO derived from Angeli's salt. HNO increased the maximal rate of thapsigargin-sensitive Ca 2؉ uptake mediated by SERCA in sarcoplasmic vesicles and caused reversible oxidative modification of SERCA thiols. HNO increased the S-glutathiolation of SERCA, and adenoviral overexpression of glutaredoxin-1 prevented both the HNO-stimulated oxidative modification of SERCA and its activation, as did overexpression of a mutated SERCA in which cysteine 674 was replaced with serine. Thus, HNO increases the maximal activation of SERCA via S-glutathiolation at cysteine 674. N itroxyl (HNO), the 1-electron reduced and protonated form of nitric oxide (NO), exerts a bioactivity profile that differs markedly from NO 1,2 and other reactive nitrogen species such as peroxynitrite. 3 In the cardiovascular system, HNO derived from Angeli's salt (AS) exerts inotropic and lusitropic effects in the myocardium 4 and causes relaxation of vascular smooth muscle. 5,6 These observations have raised the possibility that HNO is involved in cardiovascular regulation and/or may have therapeutic potential.In cardiac myocytes, HNO increases calcium cycling in association with increasing the activities of SERCA (sarcoplasmic reticulum ATPase) and the calcium release channel (CRC). 1 In vascular smooth muscle cells SERCA activity can be increased by NO-induced S-glutathiolation. 7 Accordingly, we hypothesized that in cardiac myocytes HNO can activate SERCA via S-glutathiolation. Materials and MethodsIn all experiments, adult rat ventricular myocytes (ARVMs) 8 were exposed for 15 minutes to 500 mol/L AS dissolved in 10 mmol/L NaOH. Detailed methods are provided in the online supplement at http://circres.ahajournals.org. Results and Discussion HNO Activation of SERCA Involves Reversible, Oxidative Thiol ModificationAS increased myocyte shortening (Ϸ2-fold) and accelerated relaxation ( Figure I in the online data supplement), confirming the findings of Tocchetti et al. 1 In the absence of dithiothreitol (DTT), AS (500 mol/L; 15 minutes) increased maximal SERCA activity Ϸ3-fold ( Figure 1A). In the pres-

Myocardial failure is associated with increased oxidative stress and abnormal excitation-contraction coupling characterized by depletion of sarcoplasmic reticulum (SR) Ca 2+ -stores and a reduction in Ca 2+ -transient amplitude. Little is known about the mechanisms whereby oxidative stress affects Ca 2+ -handling and contractile function; however, reactive thiols may be involved. We used an in vitro cardiomyocyte system to test the hypothesis that short-term oxidative stress induces SR Ca 2+ -depletion via redox-mediated regulation of sarco-endoplasmic reticulum Ca 2+ -ATPase (SERCA) and the sodium-Ca 2+ -exchanger (NCX) and that this is associated with thiol oxidation. Adult rat ventricular myocytes paced at 5 Hz were superfused with H 2 O 2 (100 μM, 15 min). H 2 O 2 caused a progressive decrease in cell shortening followed by diastolic arrest, which was associated with decreases in SR Ca 2+ -content, systolic [Ca 2+ ] i and Ca 2+ -transient amplitude, but no change in diastolic [Ca 2+ ] i . H 2 O 2 caused reciprocal effects on the activities of SERCA (decreased) and NCX (increased). Pretreatment with the NCX inhibitor KB-R7943 prior to H 2 O 2 increased diastolic [Ca 2+ ] i , and mimicked the effect of SERCA inhibition with thapsigargin. These functional effects were associated with oxidative modification of thiols on both SERCA and NCX. In conclusion, redox-mediated SR Ca 2+ -depletion involves reciprocal regulation of SERCA and NCX, possibly via direct oxidative modification of both proteins.

BackgroundA hallmark of aging of the cardiac myocyte is impaired sarcoplasmic reticulum (SR) calcium uptake and relaxation due to decreased SR calcium ATPase (SERCA) activity. We tested the hypothesis that H2O2‐mediated oxidation of SERCA contributes to impaired myocyte relaxation in aging.Methods and ResultsYoung (5‐month‐old) and senescent (21‐month‐old) FVB wild‐type (WT) or transgenic mice with myocyte‐specific overexpression of catalase were studied. In senescent mice, myocyte‐specific overexpression of catalase (1) prevented oxidative modification of SERCA as evidenced by sulfonation at Cys674, (2) preserved SERCA activity, (3) corrected impaired calcium handling and relaxation in isolated cardiac myocytes, and (4) prevented impaired left ventricular relaxation and diastolic dysfunction. Nitroxyl, which activates SERCA via S‐glutathiolation at Cys674, failed to activate SERCA in freshly isolated ventricular myocytes from senescent mice. Finally, in adult rat ventricular myocytes in primary culture, adenoviral overexpression of SERCA in which Cys674 is mutated to serine partially preserved SERCA activity during exposure to H2O2.ConclusionOxidative modification of SERCA at Cys674 contributes to decreased SERCA activity and impaired myocyte relaxation in the senescent heart. Strategies to decrease oxidant levels and/or protect target proteins such as SERCA may be of value to preserve diastolic function in the aging heart.

Continued smoking causes tumor progression and resistance to therapy in lung cancer. Carcinogens possess the ability to block apoptosis, and thus may induce development of cancers and resistance to therapy. Tobacco carcinogens have been studied widely; however, little is known about the agents that inhibit apoptosis, such as nicotine. We determine whether mitochondrial signaling mediates antiapoptotic effects of nicotine in lung cancer. A549 cells were exposed to nicotine (1 muM) followed by cisplatin (35 muM) plus etoposide (20 muM) for 24 hours. We found that nicotine prevented chemotherapy-induced apoptosis, improved cell survival, and caused modest increases in DNA synthesis. Inhibition of mitogen-activated protein kinase (MAPK) and Akt prevented the antiapoptotic effects of nicotine and decreased chemotherapy-induced apoptosis. Small interfering RNA MAPK kinase-1 blocked antiapoptotic effects of nicotine, whereas small interfering RNA MAPK kinase-2 blocked chemotherapy-induced apoptosis. Nicotine prevented chemotherapy-induced reduction in mitochondrial membrane potential and caspase-9 activation. Antiapoptotic effects of nicotine were blocked by mitochondrial anion channel inhibitor, 4,4'diisothiocyanatostilbene-2,2'disulfonic acid. Chemotherapy enhanced translocation of proapoptotic Bax to the mitochondria, whereas nicotine blocked these effects. Nicotine up-regulated Akt-mediated antiapoptotic X-linked inhibitor of apoptosis protein and phosphorylated proapoptotic Bcl2-antagonist of cell death. The A549-rho0 cells, which lack mitochondrial DNA, demonstrated partial resistance to chemotherapy-induced apoptosis, but blocked the antiapoptotic effects of nicotine. Accordingly, we provide evidence that nicotine modulates mitochondrial signaling and inhibits chemotherapy-induced apoptosis in lung cancer. The mitochondrial regulation of nicotine imposes an important mechanism that can critically impair the treatment of lung cancer, because many cancer-therapeutic agents induce apoptosis via the mitochondrial death pathway. Strategies aimed at understanding nicotine-mediated signaling may facilitate the development of improved therapies in lung cancer.

Background: Myocyte contractile dysfunction occurs in pathological remodeling in association with abnormalities in calcium regulation. Mice with cardiac myocyte-specific overexpression of G␣q develop progressive left ventricular failure associated with myocyte contractile dysfunction and calcium dysregulation. Objective:We tested the hypothesis that myocyte contractile dysfunction in the G␣q mouse heart is mediated by reactive oxygen species, and in particular, oxidative posttranslational modifications, which impair the function of sarcoplasmic reticulum Ca

SummaryKallistatin, an endogenous protein, protects against vascular injury by inhibiting oxidative stress and inflammation in hypertensive rats and enhancing the mobility and function of endothelial progenitor cells (EPCs). We aimed to determine the role and mechanism of kallistatin in vascular senescence and aging using cultured EPCs, streptozotocin (STZ)‐induced diabetic mice, and Caenorhabditis elegans (C. elegans). Human kallistatin significantly decreased TNF‐α‐induced cellular senescence in EPCs, as indicated by reduced senescence‐associated β‐galactosidase activity and plasminogen activator inhibitor‐1 expression, and elevated telomerase activity. Kallistatin blocked TNF‐α‐induced superoxide levels, NADPH oxidase activity, and microRNA‐21 (miR‐21) and p16INK 4a synthesis. Kallistatin prevented TNF‐α‐mediated inhibition of SIRT1, eNOS, and catalase, and directly stimulated the expression of these antioxidant enzymes. Moreover, kallistatin inhibited miR‐34a synthesis, whereas miR‐34a overexpression abolished kallistatin‐induced antioxidant gene expression and antisenescence activity. Kallistatin via its active site inhibited miR‐34a, and stimulated SIRT1 and eNOS synthesis in EPCs, which was abolished by genistein, indicating an event mediated by tyrosine kinase. Moreover, kallistatin administration attenuated STZ‐induced aortic senescence, oxidative stress, and miR‐34a and miR‐21 synthesis, and increased SIRT1, eNOS, and catalase levels in diabetic mice. Furthermore, kallistatin treatment reduced superoxide formation and prolonged wild‐type C. elegans lifespan under oxidative or heat stress, although kallistatin's protective effect was abolished in miR‐34 or sir‐2.1 (SIRT1 homolog) mutant C. elegans. Kallistatin inhibited miR‐34, but stimulated sir‐2.1 and sod‐3 synthesis in C. elegans. These in vitro and in vivo studies provide significant insights into the role and mechanism of kallistatin in vascular senescence and aging by regulating miR‐34a‐SIRT1 pathway.

BACKGROUND: Preoperative peripheral blood neutrophil-to-lymphocyte ratio (NLR) has been proposed to predict prognosis of hepatocellular carcinoma (HCC). However, the cutoff value of NLR in several studies is not consistent. This study aims to investigate the correlation of preoperative NLR with clinicopathologic features and the prognosis in patients who have undergone resection for HCC. METHODS: Clinical data of 256 patients with HCC who underwent radical hepatectomy were retrospectively analyzed. The patients were divided into the low-NLR group (NLR ≤ 2.31) and the high-NLR group (NLR > 2.31). A univariate analysis was performed to assess clinicopathologic characteristics that influenced disease-free survival (DFS) and overall survival (OS) in patients. The significant variables were further analyzed by a multivariate analysis using Cox regression. The Kaplan-Meier method was used to assess the DFS and OS rate. RESULTS: The value of NLR was associated with tumor size, clinical tumor-node-metastasis (TNM) stage, portal vein tumor thrombus (PVTT), distant metastasis, and aspartate aminotransferase (AST) in HCC. NLR > 2.31, size of tumor > 5 cm, number of multiple tumors, III-IV of TNM stage, PVTT, distant metastasis, and AST > 40 U/l were predictors of poorer DFS and OS. NLR > 2.31, size of tumor > 5 cm, III-IV of TNM stage, and AST > 40 U/l were independent predictors of DFS and OS. CONCLUSION: Preoperative NLR > 2.31 was an adverse predictor of DFS and OS in HCC after hepatectomy. This study suggested that NLR might be a novel prognostic biomarker in HCC after curative resection.

Methylation of CpG islands and associated gene silencing may lead to malignant progression, but the mechanisms of CpG island methylation in cancer are unknown. The tazarotene-induced gene 1 (TIG1), also known as retinoid acid (RA) receptor-responsive 1 gene was first identified as an RA-responsive gene and was shown to be downregulated in prostate cancer. Here, we show that this downregulation is caused by the methylation of the promoter and CpG island of TIG1. TIG1 was methylated in 26 of 50 (52%) primary prostate cancers, but was not methylated in normal tissues or benign hyperplasias. Three of four tumors that metastasized, five of six that were poorly differentiated and all that were assigned a Gleason score higher than 8 (7/7) were methylated in the promoter of TIG1. The samples with peripheral invasion were more frequently methylated (21/32, 66%) than tissues without peripheral invasion (5/18, 28%). In addition, Gleason 7-10 cancers (21/30, 70%) were significantly more frequently methylated compared with Gleason 4-6 cancers (4/18, 22%) (Po0.01). The retinoic acid receptor beta (RAR-beta) gene was frequently methylated as well (42/50, 84%). When TIG1 showed methylation, RAR-beta was also methylated (25/26 samples). In almost all samples where RAR-beta was not methylated, TIG1 was also in an unmethylated state (14/15 samples). The methylation of TIG1 and RAR-beta was positively correlated (r ¼ 0.35; P ¼ 0.017). It is possible that the methylation of the retinoid response gene TIG1 occurred in response to the methylation and inactivation of RAR-beta. These observations may contribute to our understanding of mechanistic events leading to CpG island methylation in cancer.