The Role of GCN2 in Ponatinib-Induced Cardiotoxicity

About This Grant

PROJECT SUMMARY This proposal outlines a five-year plan to prepare Dr. Gege Yan for an independent research career. The plan aims to enhance Dr. Yan's expertise in cardio-oncology through specialized training in sequencing technology, stem cell biology, mitochondrial biology, and oncology. During the K99 phase, Dr. Yan will be guided by the advisory committee, take formal courses, complete demanding research projects, and join a career transition program. Cancer ranks second in global mortality, preceded only by cardiovascular diseases. Targeted therapies have improved cancer patient outcomes, but shared signaling pathways between cancerous and noncancerous cells can result in cardiac toxicity from anticancer drugs instead of the cancer itself. Ponatinib, a tyrosine kinase inhibitor (TKI) used to treat chronic myeloid leukemia (CML), was temporarily withdrawn from the market a decade ago due to severe cardiac and vascular toxicity. It serves as a last resort for CML patients when other TKIs fail to halt cancer progression. Ponatinib inhibits over 60 kinases, making understanding its cardiac toxicity challenging. There has been a lack of emphasis on enhancing its anticancer efficacy while protecting the heart. Dr. Yan utilized human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to model ponatinib- induced cardiomyocyte injury and found that it's linked to the activation of the integrated stress response (ISR) pathway through proteomic analysis. She identified general control nonderepressible 2 (GCN2) as the eIF2α kinase responsible for relaying mitochondrial stress signals to trigger the primary ISR effector activating transcription factor 4 (ATF4) upon ponatinib exposure. Mechanistically, ponatinib perturbed mitochondrial function results in ATP deficits and subsequently triggers GCN2-mediated ISR activation. Moreover, administering the ISR inhibitor ISRIB is cardioprotective against ponatinib when given at disease onset both in vitro and in vivo. Importantly, ISRIB does not affect the antitumor effects of ponatinib in vitro. In this study, to determine whether GCN2-mediated ISR regulates ponatinib-induced cardiotoxicity is specific to cardiomyocytes, Dr. Yan will use hiPSC-derived endothelial cells, human primary cardiac fibroblasts, and a cardiac-specific knockout mouse model to explore the role of GCN2 in ponatinib-induced cardiotoxicity in vitro and in vivo (Aim 1). She will employ ATF4 ChIP-seq and phospho-profiling to identify the precise downstream signature of GCN2 that drives ponatinib-induced cardiotoxicity (Aim 2). Furthermore, she will investigate whether administering ISRIB after the manifestation of ponatinib-induced cardiotoxicity, which is more clinically relevant, is protective. Moreover, she plans to use a xenograft mouse model to investigate whether ISRIB can enhance the antitumor efficacy of ponatinib (Aim 3). In summary, this study proposes an innovative solution to reduce ponatinib-induced cardiotoxicity, offering the potential for improved and extended lives for cancer survivors. Furthermore, completing these studies will lay the foundation for Dr. Yan's transition to her own independent research program.