Insulin Protects Cardiac Myocytes from Doxorubicin Toxicity by Sp1-Mediated Transactivation of Survivin.
Insulin inhibits ischemia/reperfusion-induced myocardial apoptosis through the PI3K/Akt/mTOR pathway. Survivin is a key regulator of anti-apoptosis against doxorubicin-induced cardiotoxicity. Insulin increases survivin expression in cardiac myocytes to mediate cytoprotection. However, the mechanism by which survivin mediates the protective effect of insulin against doxorubicin-associated injury remains to be determined. In this study, we demonstrated that pretreatment of H9c2 cardiac myocytes with insulin resulted in a significant decrease in doxorubicin-induced apoptotic cell death by reducing cytochrome c release and caspase-3 activation. Doxorubicin-induced reduction of survivin mRNA and protein levels was also significantly perturbed by insulin pretreatment. Reducing survivin expression with survivin siRNA abrogated insulin-mediated inhibition of caspase-3 activation, suggesting that insulin signals to survivin inhibited caspase-3 activation. Interestingly, pretreatment of H9c2 cells with insulin or MG132, a proteasome inhibitor, inhibited doxorubicin-induced degradation of the transcription factor Sp1. ChIP assay showed that pretreatment with insulin inhibited doxorubicin-stimulated Sp1 dissociation from the survivin promoter. Finally using pharmacological inhibitors of the PI3K pathway, we showed that insulin-mediated activation of the PI3K/Akt/mTORC1 pathway prevented doxorubicin-induced proteasome-mediated degradation of Sp1. Taken together, insulin pretreatment confers a protective effect against doxorubicin-induced cardiotoxicity by promoting Sp1-mediated transactivation of survivin to inhibit apoptosis. Our study is the first to define a role for survivin in cellular protection by insulin against doxorubicin-associated injury and show that Sp1 is a critical factor in the transcriptional regulation of survivin.
Graduate Program in Science for Aging, Yonsei University, Seoul, Republic of Korea; Yonsei Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; Severance Integrative Research Institute for Cerebral and Cardiovascular Diseases (SIRIC), Yonsei University Health System, Seoul, Republic of Korea.
Beom Seob
BS
Lee
Cardiology Division, Severance Cardiovascular Hospital, Seoul, Republic of Korea; Yonsei Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
Jaewon
J
Oh
Avon Old Farms School, Avon, Connecticut, United States of America.
Sung Ku
SK
Kang
Cardiology Division, Severance Cardiovascular Hospital, Seoul, Republic of Korea; Yonsei Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
Sungha
S
Park
Cardiology Division, Severance Cardiovascular Hospital, Seoul, Republic of Korea; Yonsei Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
Sang-Hak
SH
Lee
Cardiology Division, Severance Cardiovascular Hospital, Seoul, Republic of Korea; Yonsei Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; Severance Integrative Research Institute for Cerebral and Cardiovascular Diseases (SIRIC), Yonsei University Health System, Seoul, Republic of Korea.
Donghoon
D
Choi
Department of Applied Bioscience, College of Life Science, CHA University, Gyeonggi-do, Republic of Korea.
Ji Hyung
JH
Chung
Yonsei Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea.
Youn Wook
YW
Chung
Cardiology Division, Severance Cardiovascular Hospital, Seoul, Republic of Korea; Yonsei Cardiovascular Research Institute, Yonsei University College of Medicine, Seoul, Republic of Korea; Severance Integrative Research Institute for Cerebral and Cardiovascular Diseases (SIRIC), Yonsei University Health System, Seoul, Republic of Korea.
Seok-Min
SM
Kang
D000818:Animals; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D047369:Chromatin Immunoprecipitation; D004317:Doxorubicin / Q000494:pharmacology*; D007328:Insulin / Q000494:pharmacology*; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000187:drug effects*; D034622:RNA Interference; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D000077022:Survivin
C516989:Birc5 protein, rat; D007328:Insulin; D008869:Microtubule-Associated Proteins; D016329:Sp1 Transcription Factor; D000077022:Survivin; D004317:Doxorubicin