Ischaemic Preconditioning Protects Cardiomyocytes from Anthracycline-Induced Toxicity via the PI3K Pathway.

PURPOSE: Anthracyclines cause chronic irreversible cardiac failure, but the mechanism remains poorly understood. Emerging data indicate that cardiac damage begins early, suggesting protective modalities delivered in the acute stage may confer prolonged benefit. Ischaemic preconditioning (IPC) activates the pro-survival reperfusion injury salvage kinase (RISK) pathway which involves PI3-kinase and MAPK/ERK1/2. METHODS: We investigated whether simulated IPC (sIPC), in the form of a sublethal exposure to a hypoxic buffer simulating ischaemic conditions followed by reoxygenation, protects primary adult rat cardiomyocytes against anthracycline-induced injury. PI3-kinase and MAPK/ERK1/2 were inhibited using LY294002, and PD98059. The role of reactive oxygen species (ROS), mitochondrial membrane potential (Δψm) and mitochondrial permeability transition pore (mPTP) were also investigated in doxorubicin-treated cells. We further examined whether sIPC protected HeLa cancer cells from doxorubicin-induced death. RESULTS: sIPC protected cardiomyocytes against doxorubicin-induced death (35.4 ± 1.7% doxorubicin vs 14.7 ± 1.5% doxorubicin + sIPC; p < 0.01). This protection was abrogated by the PI3-kinase inhibitor, LY294002, but not the MAPK/ERK1/2 inhibitor, PD98059. A ROS scavenger failed to rescue cardiomyocytes from doxorubicin toxicity, and no significant influence on Δψm or mPTP opening was identified after subjecting cells to a doxorubicin insult. Importantly, sIPC did not protect HeLa cancer cells from doxorubicin-induced death. CONCLUSION: sIPC is able to protect cardiomyocytes against anthracycline injury via a pathway involving PI3-kinase. This mechanism appears to be independent of ROS, changes to Δψm, and mPTP. Further investigation of the mechanism of sIPC-induced protection against anthracycline-injury is warranted.

Anthracycline Chemotherapy and Cardiotoxicity.

Anthracycline chemotherapy maintains a prominent role in treating many forms of cancer. Cardiotoxic side effects limit their dosing and improved cancer outcomes expose the cancer survivor to increased cardiovascular morbidity and mortality. The basic mechanisms of cardiotoxicity may involve direct pathways for reactive oxygen species generation and topoisomerase 2 as well as other indirect pathways. Cardioprotective treatments are few and those that have been examined include renin angiotensin system blockade, beta blockers, or the iron chelator dexrazoxane. New treatments exploiting the ErbB or other novel pro-survival pathways, such as conditioning, are on the cardioprotection horizon. Even in the forthcoming era of targeted cancer therapies, the substantial proportion of today's anthracycline-treated cancer patients may become tomorrow's cardiac patient.

Effect of Remote Ischaemic Conditioning in Oncology Patients Undergoing Chemotherapy: Rationale and Design of the ERIC-ONC Study--A Single-Center, Blinded, Randomized Controlled Trial.

Cancer survival continues to improve, and thus cardiovascular consequences of chemotherapy are increasingly important determinants of long-term morbidity and mortality. Conventional strategies to protect the heart from chemotherapy have important hemodynamic or myelosuppressive side effects. Remote ischemic conditioning (RIC) using intermittent limb ischemia-reperfusion reduces myocardial injury in the setting of percutaneous coronary intervention. Anthracycline cardiotoxicity and ischemia-reperfusion injury share common biochemical pathways in cardiomyocytes. The potential for RIC as a novel treatment to reduce subclinical myocyte injury in chemotherapy has never been explored and will be investigated in the Effect of Remote Ischaemic Conditioning in Oncology (ERIC-ONC) trial (clinicaltrials.gov NCT 02471885). The ERIC-ONC trial is a single-center, blinded, randomized, sham-controlled study. We aim to recruit 128 adult oncology patients undergoing anthracycline-based chemotherapy treatment, randomized in a 1:1 ratio into 2 groups: (1) sham procedure or (2) RIC, comprising 4, 5-minute cycles of upper arm blood pressure cuff inflations and deflations, immediately before each cycle of chemotherapy. The primary outcome measure, defining cardiac injury, will be high-sensitivity troponin-T over 6 cycles of chemotherapy and 12 months follow-up. Secondary outcome measures will include clinical, electrical, structural, and biochemical endpoints comprising major adverse cardiovascular clinical events, incidence of cardiac arrhythmia over 14 days at cycle 5/6, echocardiographic ventricular function, N-terminal pro-brain natriuretic peptide levels at 3 months follow-up, and changes in mitochondrial DNA, micro-RNA, and proteomics after chemotherapy. The ERIC-ONC trial will determine the efficacy of RIC as a novel, noninvasive, nonpharmacological, low-cost cardioprotectant in cancer patients undergoing anthracycline-based chemotherapy.