Doxorubicin (DOX) is a widely used chemotherapy agent. The major adverse effect 
of DOX treatment in cancer patients is the onset of cardiomyopathy and heart 
failure. Reactive oxygen species (ROS) are proposed to be responsible for DOX 
cardiotoxicity. Curcumin, a natural compound extracted from Curcuma Longa L., is 
known for its anti-oxidant properties. It has been identified as increased 
apoptosis in several cancer cell lines in combination with doxorubicin, but 
there are few studies about the effect of curcumin and doxorubicin on normal 
cardiac cells. Therefore, we evaluated the effects of curcumin on apoptosis 
induced by DOX in cardiac muscle cells. Pretreatment with curcumin significantly 
increased DOX-induced apoptosis of cardiac muscle cells through down regulation 
of Bcl-2, up-regulation of caspase-8 and caspase-9. The Bax/Bcl-2 ratio 
increased significantly after 1h pretreatment with curcumin. As well, curcumin 
increases ROS generation by DOX. In response to DOX, NF-κB was activated. 
However, curcumin was able to inhibit NF-κB activation. In conclusion, our 
results indicated that pretreatment with nontoxic concentrations of curcumin 
sensitized H9c2 cells to DOX-mediated apoptosis by generation of ROS.