Integrated Stress Response Potentiates Ponatinib-Induced Cardiotoxicity

Abstract

Background: Mitochondrial dysfunction is a primary driver of cardiac contractile failure; yet, the cross talk between mitochondrial energetics and signaling regulation remains obscure. Ponatinib, a tyrosine kinase inhibitor used to treat chronic myeloid leukemia, is among the most cardiotoxic tyrosine kinase inhibitors and causes mitochondrial dysfunction. Whether ponatinib-induced mitochondrial dysfunction triggers the integrated stress response (ISR) to induce ponatinib-induced cardiotoxicity remains to be determined. Methods: Using human-induced pluripotent stem cells–derived cardiomyocytes (hiPSC-CMs) and a recently developed mouse model of ponatinib-induced cardiotoxicity, we performed proteomic analysis, molecular and biochemical assays to investigate the relationship between ponatinib-induced mitochondrial stress and ISR and their role in promoting ponatinib-induced cardiotoxicity. Results: Proteomic analysis revealed that ponatinib activated the ISR in cardiac cells. We identified GCN2 (general control nonderepressible 2) as the eIF2α (eukaryotic translation initiation factor) kinase responsible for relaying mitochondrial stress signals to trigger the primary ISR effector—ATF4 (activating transcription factor 4), upon ponatinib exposure. Mechanistically, ponatinib treatment exerted inhibitory effects on ATP synthase activity and reduced its expression levels resulting in ATP deficits. Perturbed mitochondrial function resulting in ATP deficits then acts as a trigger of GCN2-mediated ISR activation, effects that were negated by nicotinamide mononucleotide, an NAD + precursor, supplementation. Genetic inhibition of ATP synthase also activated GCN2. Interestingly, we showed that the decreased abundance of ATP also facilitated direct binding of ponatinib to GCN2, unexpectedly causing its activation most likely because of a conformational change in its structure. Importantly, administering an ISR inhibition, ISRIB, protected human-induced pluripotent stem cell–derived cardiomyocytes against ponatinib. Ponatinib-treated mice also exhibited reduced cardiac function, effects that were attenuated upon systemic ISRIB administration. Importantly, ISRIB does not affect the antitumor effects of ponatinib in vitro. Conclusions: Neutralizing ISR hyperactivation could prevent or reverse ponatinib-induced cardiotoxicity. The findings that compromised ATP production potentiates GCN2-mediated ISR activation have broad implications across various cardiac diseases. Our results also highlight an unanticipated role of ponatinib in causing direct activation of a kinase target despite its role as an ATP-competitive kinase inhibitor.

Detection of a Mitochondrial Fragmentation and Integrated Stress Response Using the Cell Painting Assay

“…Considering that ISR is implicated in different diseases, strategies for pharmacological modulation of ISR have been explored. , ISR induction by the small molecule BTM-3566 was shown to cause growth arrest and apoptosis in diffuse large B-cell lymphoma (DLBL) and complete regression in patient-derived xenografts, demonstrating that induction of ATF4 response may be beneficial for cancer treatment. On the other hand, ISR has been linked to an increase in ponatinib-induced cardiotoxicity and drug-induced liver injury . In these studies, ISR was detected upon transcriptome or proteome profiling.…”

Ponatinib-Induced Cardiomyocyte Toxicity: Dark Side of the Integrated Stress Response

“…While mentioned in some reviews, the primary data documenting this potential complication is not readily available. However, ponatinib clearly induces contractile dysfunction and cell death in human cardiomyocytes 1 and decreases systolic function in zebrafish. 3 While ponatinib does not provoke systolic dysfunction in mice at baseline, it induces systolic dysfunction in the context of the pro-atherogenic/inflammatory milieu of high-fat diet-fed APOE (apolipoprotein E) knockout mice and exacerbates systolic dysfunction in wild-type mice subjected to pressure overload.…”