TY - JOUR
T1 - Adverse Effects of Doxorubicin and Its Metabolic Product on Cardiac RyR2 and SERCA2A
AU - Hanna, Amy
AU - Lam, Alex
AU - Tham, Steffi
AU - dulhunty, Angela
AU - BEARD, Nicole
N1 - Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.
PY - 2014/10
Y1 - 2014/10
N2 - The use of anthracycline chemotherapeutic drugs is restricted owing to potentially fatal cardiotoxic side effects. It has been hypothesized that anthracycline metabolites have a primary role in this cardiac dysfunction; however, information on the molecular interactions of these compounds in the heart is scarce. Here we provide novel evidence that doxorubicin and its metabolite, doxorubicinol, bind to the cardiac ryanodine receptor (RyR2) and to the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA2A) and deleteriously alter their activity. Both drugs (0.01 μM–2.5 μM) activated single RyR2 channels, and this was reversed by drug washout. Both drugs caused a secondary inhibition of RyR2 activity that was not reversed by drug washout. Preincubation with the reducing agent dithiothreitol (DTT, 1 mM) prevented drug-induced inhibition of channel activity. Doxorubicin and doxorubicinol reduced the abundance of thiol groups on RyR2, further indicating that oxidation reactions may be involved in the actions of the compounds. Ca2+ uptake into sarcoplasmic reticulum vesicles by SERCA2A was inhibited by doxorubicinol, but not doxorubicin. Unexpectedly, in the presence of DTT, doxorubicinol enhanced the rate of Ca2+ uptake by SERCA2A. Together the evidence provided here shows that doxorubicin and doxorubicinol interact with RyR2 and SERCA2A in similar ways, but that the metabolite acts with greater efficacy than the parent compound. Both compounds modify RyR2 and SERCA2A activity by binding to the proteins and also act via thiol oxidation to disrupt SR Ca2+ handling. These actions would have severe consequences on cardiomyocyte function and contribute to clinical symptoms of acute anthracycline cardiotoxicity
AB - The use of anthracycline chemotherapeutic drugs is restricted owing to potentially fatal cardiotoxic side effects. It has been hypothesized that anthracycline metabolites have a primary role in this cardiac dysfunction; however, information on the molecular interactions of these compounds in the heart is scarce. Here we provide novel evidence that doxorubicin and its metabolite, doxorubicinol, bind to the cardiac ryanodine receptor (RyR2) and to the sarco/endoplasmic reticulum Ca2+ ATPase (SERCA2A) and deleteriously alter their activity. Both drugs (0.01 μM–2.5 μM) activated single RyR2 channels, and this was reversed by drug washout. Both drugs caused a secondary inhibition of RyR2 activity that was not reversed by drug washout. Preincubation with the reducing agent dithiothreitol (DTT, 1 mM) prevented drug-induced inhibition of channel activity. Doxorubicin and doxorubicinol reduced the abundance of thiol groups on RyR2, further indicating that oxidation reactions may be involved in the actions of the compounds. Ca2+ uptake into sarcoplasmic reticulum vesicles by SERCA2A was inhibited by doxorubicinol, but not doxorubicin. Unexpectedly, in the presence of DTT, doxorubicinol enhanced the rate of Ca2+ uptake by SERCA2A. Together the evidence provided here shows that doxorubicin and doxorubicinol interact with RyR2 and SERCA2A in similar ways, but that the metabolite acts with greater efficacy than the parent compound. Both compounds modify RyR2 and SERCA2A activity by binding to the proteins and also act via thiol oxidation to disrupt SR Ca2+ handling. These actions would have severe consequences on cardiomyocyte function and contribute to clinical symptoms of acute anthracycline cardiotoxicity
KW - Doxorubicin
KW - Pharmacology
KW - Cardiac
UR - http://www.scopus.com/inward/record.url?scp=84907918245&partnerID=8YFLogxK
U2 - 10.1124/mol.114.093849
DO - 10.1124/mol.114.093849
M3 - Article
C2 - 25106424
SN - 0026-895X
VL - 86
SP - 438
EP - 449
JO - Molecular Pharmacology
JF - Molecular Pharmacology
IS - 4
ER -