Evolocumab, a PCSK9 inhibitor, co-incubated with doxorubicin and trastuzumab reduces death of cardiomyocytes through reduction of MyD88-NLRP3-NF-kB-mTORC1

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Abstract Introduction Inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) is a novel treatment for hypercholesterolaemia; recent studies evidenced that PCSK9i reduces cardiovascular diseases and risk of atherosclerosis. Evolocumab, a PCSK9i, reduced the risk of cardiovascular events in patients with atherosclerotic cardiovascular diseases when added to maximally tolerated statin therapy (± ezetimibe), and recent data from the ODYSSEY OUTCOMES trial indicate that alirocumab added to maximally tolerated statin therapy (± other lipid-lowering drugs) reduces the risk of cardiovascular events in patients with a recent acute coronary syndrome. Purpose Considering the expression of PCSK9 in heart tissues and cardiomyocytes, we aimed to study for the first time the putative cellular effects of evolocumab in human cardiomyocytes incubated with doxorubicin, trastuzumab, their sequential treatments Methods Human fetal cardiomyocytes (HFC cell line) were exposed to subclinical concentration of doxorubicin, trastuzumab, sequential treatment of both (all 100 nM), alone or in combination with evolocumab (50 nM) for 48h. After the incubation period, we performed the following tests: determination of cell viability, through analysis of mitochondrial dehydrogenase activity, study of lipid peroxidation (quantifying cellular Malondialdehyde and 4-hydroxynonenal), intracellular Ca2+ homeostasis. Moreover, pro-inflammatory studied were also performed (activation of NLRP3 inflammasome; expression of TLR4/MyD88; mTORC1 Fox01/3a; transcriptional activation of p65/NF-κB and secretion of cytokines involved in cardiotoxicity (Interleukins 1β, 8, 6). Results Evolocumab co-incubated with doxorubicin alone or in sequence with trastuzumab exerts cardioprotective effects, enhancing cell viability of 35–43% compared to untreated cells (p<0,05 for all); Evolocumab reduced significantly the cardiotoxicity through MyD88/NF-KB/cytokines axis and mTORC1 Fox01/3α mediated mechanisms. Conclusion PCSK9 inhibitor evolocumab exerts direct cellular effects in cardiomyocytes during doxorubicin and trastuzumab exposure with anti-inflammatory effects. These results indicated that evolocumab should be studied in cancer-bearing mice treated with anthracyclines and HER2-blocking agents in order to reduces cardiovascular events. Funding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministero della Salute, Ricerca Corrente Project