Regulation of platelet function by cantharidin via PI3K/Akt/PKC pathway / 中国药理学通报

To investigate the effect of cantharidin ( CTD) on platelet function and the mechanism of anti-platelet aggregation. Methods Washed platelets were collected from the venous blood of healthy volunteers. The effect of CTD on platelet aggregation and release was determined by aggregometer. The CTD concentration was 2.5 ,5 ,10 μmol • L

Combined postconditioning with ischemia and α7nAChR agonist produces an enhanced protection against rat myocardial ischemia reperfusion injury / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Inflammation is one of important mechanisms for myocardial ischemia reperfusion injury (IRI). Ischemia postconditioning (IPOC) can protect the heart against IRI by inhibiting inflammation, but its cardioprotection is weaker than that of ischemia preconditioning. Recently, the α7 subunit-containing nicotinic acetylcholine receptor (α7nAChR) agonist has shown anti-inflammatory effects in many diseases related to inflammation. This randomized controlled experiment was designed to evaluate whether combined postconditioning with IPOC and the α7nAChR agonist could produce an enhanced cardioprotection in a rat in vivo model of acute myocardial IRI.</p><p><b>METHODS</b>Fifty Sprague-Dawley rats were randomly divided into five equal groups: sham group, control group, IPOC group, α7nAChR agonist postconditioning group (APOC group) and combined postconditioning with IPOC and α7nAChR agonist group (combined group). Hemodynamic parameters were recorded during the periods of ischemia and reperfusion. Serum concentrations of troponin I (TnI), tumor necrosis factor α (TNF-α) and high-mobility group box 1 (HMGB-1) at 180 minutes after reperfusion were assayed in all groups. At the end of the experiment, the infarct size was assessed from excised hearts by Evans blue and triphenyl tetrazolium chloride staining.</p><p><b>RESULTS</b>As compared to the sham group, the infarct size in the other four groups was significantly increased, serum levels of TnI, TNF-α and HMGB1 in the control group and TNF-α, HMGB1 in the IPOC group were significantly increased. The infarct size and serum concentrations of TNF-α, HMGB1 and TnI in the IPOC, APOC and combined groups were significantly lower than those in the control group. As compared to the IPOC group, the infarct size in the combined group was significantly decreased, serum concentrations of TnI, TNF-α and HMGB1 in the APOC and combined groups were significantly reduced. Although the infarct size was significantly smaller in the combined group than in the APOC group, serum levels of TNF-α and HMGB1 were significantly higher in the combined group than in the APOC group.</p><p><b>CONCLUSIONS</b>In a rat in vivo model of acute myocardial IRI, combined postconditioning with IPOC and the α7nAChR agonist can produce enhanced protection against myocardial IRI by increasing the anti-inflammatory effect.</p>

Remote ischemia conditioning-an endogenous cardioprotective strategy from outside the heart / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>A general review was made of studies involving: (1) The experimental evidence of remote ischemic preconditioning (RIPC) and relative clinical studies, (2) The experimental and clinical evidences of remote ischemic postconditioning (RIPOC), (3) The potential mechanistic pathways underlying their protective effects.</p><p><b>DATA SOURCES</b>The data used in this review were mainly from manuscripts listed in PubMed that were published in English from 1986 to 2010. The search terms were "myocardial ischemia reperfusion injury", "ischemia preconditioning", "ischemia postconditioning", "remote preconditioning" and "remote postconditioning".</p><p><b>STUDY SELECTION</b>(1) Clinical and experimental evidence that both RIPC and RIPOC produce preservation of ischemia reperfusion injury (IRI) of myocardium and other organs, (2) Studies related to the potential mechanisms, by which remote ischemic conditioning protects myocardium against IRI.</p><p><b>RESULTS</b>Both RIPC and RIOPC have been shown to attenuate myocardial IRI in laboratory animals. Also, their cardioprotective effects have appeared in some clinical studies. Except the external, the detailed internal mechanisms of remote ischemic conditioning have been generally described. Through these descriptions better protocols can be developed to provide improved cardioprotective procedures.</p><p><b>CONCLUSIONS</b>Remote ischemic conditioning is an endogenous cardioprotective mechanism from outside the heart that protects against myocardial IRI and represents a general form of inter-organ protection. Remote ischemic conditioning may have an immense impact on clinical practice in the near future.</p>

Cholinergic anti-inflammatory pathway: a possible approach to protect against myocardial ischemia reperfusion injury / 中华医学杂志(英文版)

<p><b>OBJECTIVE</b>A general review was made of studies involving: (1) the concept and mechanism of the cholinergic anti-inflammatory pathway (CAP), (2) the important role of inflammatory response in myocardial ischemia reperfusion (I/R) injury and (3) the evidence and mechanisms by which CAP may provide protection against myocardial I/R injury.</p><p><b>DATA SOURCES</b>The data used in this review were mainly from manuscripts listed in PubMed that were published in English from 1987 to 2009. The search terms were "vagal nerve stimulation", "myocardial ischemia reperfusion injury", "nicotine acetylcholine receptor" and "inflammation".</p><p><b>STUDY SELECTION</b>(1) Clinical and experimental evidence that the inflammatory response induced by reperfusion enhances myocardial I/R injury. (2) Clinical and laboratory evidence that the CAP inhibits the inflammation and provides protection against myocardial I/R injury.</p><p><b>RESULTS</b>The myocardial I/R injury is really an inflammatory process characterized by recruitment of neutrophils into the ischemic myocardium and excessive production of pro-inflammatory cytokines. Because the CAP can modulate the inflammatory response by decreasing the production and release of pro-inflammatory cytokines, it can provide protection against myocardial I/R injury.</p><p><b>CONCLUSIONS</b>The CAP can inhibit the inflammatory response induced by reperfusion and protect against myocardial I/R injury. It represents an exciting opportunity to develop new and novel therapeutics to attenuate the myocardial I/R injury.</p>

N-(4-Hydroxyphenyl)retinamide increases dihydroceramide and synergizes with dimethylsphingosine to enhance cancer cell killing.

Fenretinide [N-(4-hydroxyphenyl)retinamide (4-HPR)] is cytotoxic in many cancer cell types. Studies have shown that elevation of ceramide species plays a role in 4-HPR cytotoxicity. To determine 4-HPR activity in a multidrug-resistant cancer cell line as well as to study ceramide metabolism, MCF-7/AdrR cells (redesignated NCI/ADR-RES) were treated with 4-HPR and sphingolipids were analyzed. TLC analysis of cells radiolabeled with [3H]palmitic acid showed that 4-HPR elicited a dose-responsive increase in radioactivity migrating in the ceramide region of the chromatogram and a decrease in cell viability. Results from liquid chromatography/electrospray tandem mass spectrometry revealed large elevations in dihydroceramides (N-acylsphinganines), but not desaturated ceramides, and large increases in complex dihydrosphingolipids (dihydrosphingomyelins, monohexosyldihydroceramides), sphinganine, and sphinganine 1-phosphate. To test the hypothesis that elevation of sphinganine participates in the cytotoxicity of 4-HPR, cells were treated with the sphingosine kinase inhibitor d-erythro-N,N-dimethylsphingosine (DMS), with and without 4-HPR. After 24 h, the 4-HPR/DMS combination caused a 9-fold increase in sphinganine that was sustained through +48 hours, decreased sphinganine 1-phosphate, and increased cytotoxicity. Increased dihydrosphingolipids and sphinganine were also found in HL-60 leukemia cells and HT-29 colon cancer cells treated with 4-HPR. The 4-HPR/DMS combination elicited increased apoptosis in all three cell lines. We propose that a mechanism of 4-HPR-induced cytotoxicity involves increases in dihydrosphingolipids, and that the synergy between 4-HPR and DMS is associated with large increases in cellular sphinganine. These studies suggest that enhanced clinical efficacy of 4-HPR may be realized through regimens containing agents that modulate sphingoid base metabolism.

A role for ceramide in driving cancer cell resistance to doxorubicin.

Advanced cancers acquire resistance to chemotherapy, and this results in treatment failure. The cellular mechanisms of chemotherapy resistance are not well understood. Here, for the first time, we show that ceramide contributes to cellular resistance to doxorubicin through up-regulating the gene expression of glucosylceramide synthase (GCS). Ceramide, a cellular lipid messenger, modulates doxorubicin-induced cell death. GCS catalyzes ceramide glycosylation, converting ceramide to glucosylceramide; this process hastens ceramide clearance and limits ceramide-induced apoptosis. In the present study, we evaluated the role of the GCS gene in doxorubicin resistance using several paired wild-type and drug-resistant (doxorubicin-selected) cancer cell lines, including breast, ovary, cervical, and colon. GCS was overexpressed in all drug-resistant counterparts, and suppressing GCS overexpression using antisense oligonucleotide restored doxorubicin sensitivity. Characterizing the effect mechanism showed that doxorubicin exposure increased ceramide levels, enhanced GCS expression, and imparted cellular resistance. Exogenous C(6)-ceramide and sphingomyelinase treatments mimicked the influence of doxorubicin on GCS, activating the GCS promoter and up-regulating GCS gene expression. Fumonisin B(1), an inhibitor of ceramide synthesis, significantly suppressed doxorubicin-up-regulated GCS expression. Promoter truncation, point mutation, gel-shift, and protein-DNA ELISA analysis showed that transcription factor Sp1 was essential for ceramide-induced GCS up-regulation. These data indicate that ceramide-governed GCS gene expression drives cellular resistance to doxorubicin.

Oligonucleotides blocking glucosylceramide synthase expression selectively reverse drug resistance in cancer cells.

High glucosylceramide synthase (GCS) activity is one factor contributing to multidrug resistance (MDR) in breast cancer. Enforced GCS overexpression has been shown to disrupt ceramide-induced apoptosis and to confer resistance to doxorubicin. To examine whether GCS is a target for cancer therapy, we have designed and tested the effects of antisense oligodeoxyribonucleotides (ODNs) to GCS on gene expression and chemosensitivity in multidrug-resistant cancer cells. Here, we demonstrate that antisense GCS (asGCS) ODN-7 blocked cellular GCS expression and selectively increased the cytotoxicity of anticancer agents. Pretreatment with asGCS ODN-7 increased doxorubicin sensitivity by 17-fold in MCF-7-AdrR (doxorubicin-resistant) breast cancer cells and by 10-fold in A2780-AD (doxorubicin-resistant) ovarian cancer cells. In MCF-7 drug-sensitive breast cancer cells, asGCS ODN-7 only increased doxorubicin sensitivity by 3-fold, and it did not influence doxorubicin cytotoxicity in normal human mammary epithelial cells. asGCS ODN-7 was shown to be more efficient in reversing drug resistance than either the GCS chemical inhibitor d-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol or the P-glycoprotein blocking agents verapamil and cyclosporin A. Experiments defining drug transport and lipid metabolism parameters showed that asGCS ODN-7 overcomes drug resistance mainly by enhancing drug uptake and ceramide-induced apoptosis. This study demonstrates that a 20-mer asGCS oligonucleotide effectively reverses MDR in human cancer cells.