Endoplasmic Reticulum Selective Autophagy Alleviates Anthracycline-Induced Cardiotoxicity

Shun Nakagama; Yasuhiro Maejima; Qintao Fan; Yuka Shiheido-Watanabe; Natsuko Tamura; Kensuke Ihara; Tetsuo Sasano

doi:10.1016/j.jaccao.2023.05.009

Endoplasmic Reticulum Selective Autophagy Alleviates Anthracycline-Induced Cardiotoxicity

JACC CardioOncol. 2023 Jul 11;5(5):656-670. doi: 10.1016/j.jaccao.2023.05.009. eCollection 2023 Oct.

Authors

Shun Nakagama¹, Yasuhiro Maejima¹, Qintao Fan¹, Yuka Shiheido-Watanabe¹, Natsuko Tamura¹, Kensuke Ihara^{1

2}, Tetsuo Sasano¹

Affiliations

¹ Department of Cardiovascular Medicine, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan.
² Department of Bio-informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan.

Abstract

Background: The administration of anthracycline drugs induces progressive and dose-related cardiac damage through several cytotoxic mechanisms, including endoplasmic reticulum (ER) stress. The unfolded protein response plays a crucial role for mitigating misfolded protein accumulation induced by excessive ER stress.

Objectives: We aimed to clarify whether endoplasmic reticulum-selective autophagy machinery (ER-phagy) serves as an alternative system to protect cardiomyocytes from ER stress caused by anthracycline drugs.

Methods: Primary cultured cardiomyocytes, H9c2 cell lines, and cardiomyocyte-specific transgenic mice, all expressing ss-RFP-GFP-KDEL proteins, were used as ER-phagy reporter models. We generated loss-of-function models using RNA interference or gene-trap mutagenesis techniques. We assessed phenotypes and molecular signaling pathways using immunoblotting, quantitative polymerase chain reaction, cell viability assays, immunocytochemical and histopathological analyses, and cardiac ultrasonography.

Results: The administration of doxorubicin (Dox) activated ER-phagy in ss-RFP-GFP-KDEL-transduced cardiomyocytes. In addition, Dox-induced cardiomyopathy models of ER-phagy reporter mice showed marked activation of ER-phagy in the myocardium compared to those of saline-treated mice. Quantitative polymerase chain reaction analyses revealed that Dox enhanced the expression of cell-cycle progression gene 1 (CCPG1), one of the ER-phagy receptors, in H9c2 cells. Ablation of CCPG1 in H9c2 cells resulted in the reduced ER-phagy activity, accumulation of proapoptotic proteins, and deterioration of cell survival against Dox administration. CCPG1-hypomorphic mice developed more severe deterioration in systolic function in response to Dox compared to wild-type mice.

Conclusions: Our findings highlight a compensatory role of CCPG1-driven ER-phagy in reducing Dox toxicity. With further study, ER-phagy may be a potential therapeutic target to mitigate Dox-induced cardiomyopathy.

Keywords: CCPG1; autophagy; doxorubicin; endoplasmic reticulum.