Doxorubicin directly binds to the cardiac-type ryanodine receptor.
The clinical use of doxorubicin, an antineoplasmic agent, is limited by its extensive cardiotoxicity which is mediated by the mobilization of intracellular Ca2+ from SR. In order to elucidate the mechanism of Ca2+ release, we analyzed the binding sites of doxorubicin on rabbit cardiac SR (sarcoplasmic reticulum). One of the binding sites was identified as cardiac-type ryanodine receptor (RyR2) which was purified by immunoprecipitation from solubilized cardiac SR in the presence of DTT. Ligand blot analysis revealed the direct binding of doxorubicin to RyR2. The binding of doxorubicin to RyR2 was specific and displaced by caffeine. Both doxorubicin and caffeine enhanced [3H]-ryanodine binding to RyR2 in a Ca2+ dependent manner. These results suggest that there is a doxorubicin binding site on RyR2.
Saeki
Kazuhiko
K
Discovery Research Laboratory, Tanabe Seiyaku Co, Saitama, Japan. kazu@tanabe.co.jp
Obi
Ichiro
I
Ogiku
Noriko
N
Shigekawa
Munekazu
M
Imagawa
Toshiaki
T
Matsumoto
Takeshi
T
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000378:metabolism*; D001665:Binding Sites; D015153:Blotting, Western; D002110:Caffeine / Q000494:pharmacology; D004317:Doxorubicin / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D066298:In Vitro Techniques; D008024:Ligands; D008297:Male; D008970:Molecular Weight; D009206:Myocardium / Q000378:metabolism*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D011233:Precipitin Tests; D011817:Rabbits; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000302:isolation & purification / Q000378:metabolism*; D012519:Sarcoplasmic Reticulum / Q000378:metabolism
D000903:Antibiotics, Antineoplastic; D008024:Ligands; D010726:Phosphodiesterase Inhibitors; D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D002110:Caffeine; D004317:Doxorubicin