Doxorubicin-induced reactive oxygen species generation and intracellular Ca2+ increase are reciprocally modulated in rat cardiomyocytes.
Doxorubicin (DOX) is one of the most potent anticancer drugs and induces acute cardiac arrhythmias and chronic cumulative cardiomyopathy. Though DOX-induced cardiotoxicity is known to be caused mainly by ROS generation, a disturbance of Ca2+ homeostasis is also implicated one of the cardiotoxic mechanisms. In this study, a molecular basis of DOX-induced modulation of intracellular Ca2+ concentration ([Ca2+]i) was investigated. Treatment of adult rat cardiomyocytes with DOX increased [Ca2+]i irrespectively of extracellular Ca2+, indicating DOX-mediated Ca2+ release from intracellular Ca2+ stores. The DOX-induced Ca2+ increase was slowly processed and sustained. The Ca2+ increase was inhibited by pretreatment with a sarcoplasmic reticulum (SR) Ca2+ channel blocker, ryanodine or dantrolene, and an antioxidant, alpha-lipoic acid or alpha-tocopherol. DOX-induced ROS generation was observed immediately after DOX treatment and increased in a time-dependent manner. The ROS production was significantly reduced by the pretreatment of the SR Ca2+ channel blockers and the antioxidants. Moreover, DOX-mediated activation of caspase-3 was significantly inhibited by the Ca2+ channel blockers and a-lipoic acid but not a-tocopherol. In addition, cotreatment of ryanodine with alpha-lipoic acid resulted in further inhibition of the casapse-3 activity. These results demonstrate that DOX-mediated ROS opens ryanodine receptor, resulting in an increase in [Ca2+]i and that the increased [Ca2+]i induces ROS production. These observations also suggest that DOX/ROS-induced increase of [Ca2+]i plays a critical role in damage of cardiomyocytes.
Kim
Seon-Young
SY
Department of Biochemistry, Chonbuk National University Medical School, Jeonju, 561-182, Korea.
Kim
Sang-Jin
SJ
Kim
Byoung-Joo
BJ
Rah
So-Young
SY
Chung
Sung Mo
SM
Im
Mie-Jae
MJ
Kim
Uh-Hyun
UH
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D053148:Caspase 3 / Q000378:metabolism; D002478:Cells, Cultured; D004317:Doxorubicin / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D008297:Male; D032383:Myocytes, Cardiac / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000138:chemical synthesis*; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000187:drug effects
D000903:Antibiotics, Antineoplastic; D000975:Antioxidants; D002121:Calcium Channel Blockers; D017382:Reactive Oxygen Species; D019837:Ryanodine Receptor Calcium Release Channel; D004317:Doxorubicin; D053148:Caspase 3; D002118:Calcium