SILAC-based proteomic analysis reveals that salidroside antagonizes cobalt chloride-induced hypoxic effects by restoring the tricarboxylic acid cycle in cardiomyocytes.

Hypoxic status alters the energy metabolism and induces cell injury in cardiomyocytes, and it further triggers the occurrence and development of cardiovascular diseases. Our previous studies have shown that salidroside (SAL) exhibits anti-hypoxic activity. However, the mechanisms remain obscure. In the present study, we successfully screened 92 different expression proteins in CoCl2-induced hypoxic conditions, 106 different expression proteins in the SAL-mediated anti-hypoxic group were compared with the hypoxic group using quantitative proteomics strategy, respectively. We confirmed that SAL showed a positive protective function involving the acetyl-CoA metabolic, tricarboxylic acid (TCA) cycle using bioinformatics analysis. We also demonstrated that SAL plays a critical role in restoring the TCA cycle and in protecting cardiomyocytes from oxidative injury via up-regulation expressions of PDHE1-B, ACO2, SUCLG1, SUCLG2 and down-regulation of MDH2. SAL also inhibited H9c2 cell apoptosis by inhibiting the activation of pro-apoptotic molecules caspase 3 and caspase 9 as well as activation of the anti-apoptotic molecular Bcl-2. Additionally, SAL also improved mitochondrial membrane potential (ΔΨm), reduced reactive oxygen species (ROS) and intercellular Ca(2+) concentration ([Ca(2+)]i) accumulation and inhibited the excessive consumption of ATP in H9c2 cells.

[L-arginine suppresses ischemia/reperfusion induced up-regulation of endothelin-1 production in a rat model of acute myocardial injury].

OBJECTIVE: To examine the level of endothelin-1 (ET-1) in serum and its expression in myocardium tissue during the development of acute myocardial ischemia/reperfusion (I/R) injury in rat and the effects of L-arginine (L-Arg) administration on these indexes. METHODS: One hundred and ten Wistar rats were randomly divided into nine groups to receive: (1) sham surgery, (2)ischemia (I, by ligation of anterior descending coronary artery for 30 minutes), (3) I+reperfusion (R, by the removal of the ligature) for 0.5 hour, (4) I+R for 1 hour, (5) I+R for 2 hours; group (6) ~ (9) also received I/R treatment as in group 2 ~ 5 respectively but with L-Arg pretreatment. Blood and myocardium tissue samples were collected by the end of the experiment for the analysis of: serum level of creatine kinase (CK), lactate dehydrogenase [LDH, by enzyme linked immunosorbent assay (ELISA)], ET-1 (radioimmunoassay), and the tissue content of ET-1 mRNA/peptide [by reverse-transcription polymerase chain-reaction (RT-PCR) and Western blotting]. RESULTS: In comparison with the sham treated control animals, the serum levels of CK, LDH, and ET-1 were all significantly higher in the groups treated with I/R (particularly those exposed to reperfusion). The myocardial tissue content of ET-1 mRNA/peptide were also significantly increased in I/R treated groups (particularly the I+R 2 hours group) as compared to control (ET-1 mRNA: 0.775 ± 0.029 vs. 0.310 ± 0.076; ET-1 peptide: 0.773 ± 0.055 vs. 0.340 ± 0.099, both P < 0.05). The i.v. administration of L-Arg significantly suppressed the up-regulation of tissue content of ET-1 mRNA /peptide in I/R treated animals (ET-1 mRNA: 0.340 ± 0.049 vs. 0.775 ± 0.029; ET-1 peptide: 0.390 ± 0.094 vs. 0.773 ± 0.055, both P < 0.05). CONCLUSION: L-Arg may be tested during certain stage of I/R injury as a therapeutic intervention for the suppression of ET-1 up-regulation.

Cardiotonic steroids attenuate ERK phosphorylation and generate cell cycle arrest to block human hepatoma cell growth.

Recent studies revealed the potential of Na(+)/K(+)-ATPase as a target for anticancer therapy and showed additional modes of action of cardiotonic steroids (CSs), a diverse family of naturally derived compounds, as inhibitors of Na(+)/K(+)-ATPase. The results from epidemiological studies showed significantly lower mortality rates in cancer patients receiving CSs, which sparked interest in the anticancer properties of these drugs. The present study was designed to investigate the anticancer effect of CSs (ouabain or cinobufagin) and to elucidate the molecular mechanisms of CS activity in hepatoma cell lines (HepG2 and SMMC-7721). Ouabain and cinobufagin significantly inhibited cell proliferation by attenuating the phosphorylation of extracellular regulated kinase (ERK) and down-regulating the expression of C-myc. These CSs also induced cell apoptosis by increasing the concentration of intracellular free calcium ([Ca(2+)](i)) and induced S phase cell cycle arrest by down-regulating the expression of Cyclin A, cyclin dependent kinase 2 (CDK2) and proliferating cell nuclear antigen (PCNA) as well as up-regulating the expression of cyclin dependent kinase inhibitor 1A (p21(CIP1)). Overexpression of ERK reversed the antiproliferation effect of ouabain or cinobufagin in HepG2 and SMMC-7721 cells. Currently, the first generation of CS-based anticancer drugs (UNBS1450 and Anvirzel) are in Phase I clinical trials. These data clearly support their potential use as cancer therapies.