Both acute coronary occlusion and reperfusion of an infarct-related artery lead to significant myocardial cell death. Recent evidence has been presented that activation of the transcription factor nuclear factor-κB (NF-κB) plays a critical role in reperfusion injury. NF-κB is usually bound to its inhibitor, IκB, and classic activation of NF-κB occurs when the 20S proteasome degrades IκB that has been phosphorylated and ubiquitinated. In this study, activation of NF-κB was inhibited by systemic administration of a 20S proteasome inhibitor (PS-519) in a porcine model of myocardial reperfusion injury. The experimental protocol induced myocardial ischemia in the distribution of the left anterior descending coronary artery for 1 h with subsequent reperfusion for 3 h. A single systemic treatment with PS-519 reduced 20S proteasome activity; blocked activation of NF-κB induced by reperfusion; reduced creatine kinase, creatine kinase-muscle-brain fraction, and troponin I release from the myocardium; preserved regional myocardial function measured by segmental shortening; significantly reduced the size of myocardial infarction; and exhibited no acute toxicity. These data show that myocardial reperfusion injury can be inhibited by using proteasome inhibitors, which likely function through the inhibition of NF-κB activation.

Cancer cachexia remains a challenging clinical problem with complex pathophysiology and unreliable diagnostic tools. A blood test to detect this metabolic derangement would aid in early treatment of these patients. A 1 H NMR-based metabolomics approach was used to determine the unique metabolic fingerprint of cachexia and to search for biomarkers in serum samples taken from an established murine model of cancer cachexia. Male CD2F1 mice received a subcutaneous flank injection of C26 adenocarcinoma cells to induce experimental cancer-related cachexia. Two molecular markers of muscle atrophy, upregulation of the E3 ubiquitin ligase Muscle Ring Finger 1 (MuRF1) and aberrant glycosylation of b-dystroglycan (b-DG), were used to confirm muscle wasting in the tumorbearing mice. Serum samples were collected for metabolomic analysis during the development of the cachexia: at baseline, when the tumor was palpable, and when the mice demonstrated cachexia. The unsupervised statistical analysis demonstrated a distinct metabolic profile with the onset of cachexia. The critical metabolic changes associated with cachexia included increased levels of very low density lipoprotein (VLDL) and low density lipoprotein (LDL), with decreased serum glucose levels. Regression analysis demonstrated a very high correlation of the presence of aberrant glycosylation of b-DG with the unique metabolic profile of cachexia. This study demonstrates for the first time that metabolomics has potential as a diagnostic tool in cancer cachexia, and in further elucidating simultaneous metabolic pathway alterations due to this syndrome. In addition, variations in VLDL and LDL deserve more investigation as surrogate serum biomarkers for cancer cachexia.

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