Dissecting mechanisms of anthracycline-induced cardiotoxicity

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ABSTRACT While cancer affects more than one in three people over their lifetime, improved long-term survival has led to an increase in the incidence of adverse cardiac side-effects of cancer treatments. Anthracyclines such as doxorubicin (Dox) are a cornerstone of chemotherapy in various cancers, however, their use is complicated by anthracycline-induced cardiotoxicity, most commonly cardiomyopathy. The mechanisms at play in Dox cardiotoxicity are multifactorial and include Topoisomerase (Top)-2β-mediated DNA damage that may culminate in apoptosis. To identify novel actors in the disease process, we first conducted a comprehensive search in biomedical databases of Dox cardiotoxicity transcriptomic studies. Candidate genes were screened for responsiveness to Dox treatment, association with the Notch and Hippo pathways implicated in cardiac repair, and the control of cell death. This systematic approach led to the identification of serine incorporator-3 (serinc- 3). W e hypothesize that in the setting of Dox-induced cardiotoxicity, serinc-3 exhibits protective effects by opposing Top-2β-mediated cardiomyocyte apoptosis that we will explore in 2 Specific Aims . In Aim 1, we will determine the role of serinc-3 in Dox injury in cardiomyocytes and cancer cells. We will (i) dissect the protective role of serinc-3 on apoptosis pathways implicated in Dox cardiotoxicity, (ii) determine an association between serinc-3 and the cardioprotective Notch and Hippo pathways in cardiomyocytes, and (iii) perform transcriptome sequencing and quantification, gene network construction, and determine biochemical and functional pathway enrichment in Dox treatment following serinc-3 expression modulation, (iv) establish protein interactions with serinc-3 using a 3xFLAG tagging strategy, co-immunoprecipitation, and mass spectrometry, and (v) evaluate serinc-3 expression in breast cancer and lymphoma cells, and quantify cancer cell proliferation following Dox treatment and serinc-3 modulation. In Aim 2, we will scrutinize in vivo serinc-3 function in cardiomyocytes following adult mouse Dox treatment. We will (i) develop tamoxifen-inducible, cardiomyocyte-specific Cre-Lox mice with enhanced green fluorescent protein for successful serinc-3 Cre excision, (ii) quantify global (ejection fraction, fractional shortening) and segmental (strain, displacement) cardiac function following serinc-3 Cre-Lox knockdown or adeno-associated virus-9-mediated overexpression in the setting of chronic Dox injury, (iii) assess the effect of serinc-3 overexpression and knockdown on Dox-induced cell death pathways in vivo, and (iv) isolate cardiomyocytes from Dox treated mice to establish correlation matrices by transcriptome sequencing following modulation of serinc-3 expression. The successful implementation of the proposed research will provide novel mechanistic insights into the pathobiology of anthracycline-induced cardiotoxicity, with translational implications.