H9C2 cells on coverslips were either left untreated, treated with doxorubicin or pre-treated with quercetin prior to doxorubicin treatment before fixation and staining

H9C2 cells on coverslips were either left untreated, treated with doxorubicin or pre-treated with quercetin prior to doxorubicin treatment before fixation and staining. cardiomyocytes to repair damage after treating doxorubicin by modulating metabolic activation, protein folding and cytoskeleton rearrangement. == Conclusion == Based on a review of the literature, this study is the first to report detailed protective mechanisms for the action of quercetin against doxorubicin-induced cardiomyocyte toxicity based on in-depth cell biology and proteomic analysis. Keywords:Quercetin, Doxorubicin, Proteomics, DIGE, MALDI-TOF, Cardiomyocytes == Background == Doxorubicin is usually a chemotherapy drug, generally used in numerous malignancy treatments, such as breast cancer, lung malignancy and several other carcinoma types [1-3]. The principal mechanism of doxorubicin is usually chelating DNA, inhibiting topoisomerase II and then generating free radicals to kill malignancy cells. Reported side effects of doxorubicin include cardiotoxicity, comprising cardiomyopathy and ultimately fatal congestive heart failure. Because myocardia Eprodisate Sodium are particularly sensitive to reactive oxygen species (ROS), cumulative doxorubicinin vivocauses irreversible damage to heart cells, thus restricting clinical use of this drug [4]. Although the specific causal mechanism of doxorubicin-induced cardiotoxicity remains largely Eprodisate Sodium unclear, most of the evidence has indicated that doxorubicin is usually reduced to its semiquinone form by a mitochondria electron transport system. The semiquinone subsequently reacts with oxygen, iron, and hydrogen peroxide to produce ROS causing cell apoptosis and myocyte damage [5,6]. In addition, global analysis of doxorubicin-induced cellular oxidative stress has indicated that doxorubicin treatment contributes to the over-expression of anti-oxidant proteins such as glutathione reductase and peroxiredoxin in brain cells, lung cells and heart cells [7-9]. Quercetin, a type of polyphenolic compound found in numerous plant products, possesses anti-oxidant, anti-proliferative, anti-inflammatory and anti-histamine properties. Several reports have indicated that quercetin exerts protective effects on numerous cells, including myocytes, testes, renal cells and liver cells in ischemia and reperfusion injury [10]. A study conducted in 1992 decided that quercetin reduces the oxidative stress caused by ischemia and reperfusion in cardiomyocytes by inhibiting the xanthine dehydrogenase and xanthine oxidase system [11]. Several reports have also indicated that quercetin and isorhamnetin scavenge ROS and inhibit the activation of ERK and MAP kinase in ROS-induced cardiomyopathy [12,13]. In malignancy therapy, combining quercetin with doxorubicin augmented the effects of doxorubicin in highly invasive breast malignancy cells [14] and can protect cardiomyocytes from doxorubicin-induced toxicity by chelating iron, inducing antioxidant activity, and inhibiting carbonyl reductase [15]. Regarding proteomic analysis, the results also indicated that quercetin could down-regulate Ras GTPase-activating-like proteins and heat shock protein-90 to reduce cell migratory ability and cell survival, respectively, in malignant cancers [16,17]. Although quercetin has been reported to play a role in protecting myocardial cells from ischemia and reperfusion injury, its protective mechanism remains unclear. To investigate the role of quercetin in alleviating doxorubicin-induced cardiotoxicity, we examined the protective ability of quercetin in doxorubicin-treated rat cardiomyocytes by performing cell biological assays, such as cell viability and apoptotic analysis, as well as a quantitative proteomic analysis based on 2D-DIGE and MALDI-TOF MS identification [18]. == Methods == == Chemicals and reagents == Generic chemicals were purchased from Sigma-Aldrich (St. Louis, USA), while reagents for 2D-DIGE were purchased from GE Healthcare (Uppsala, Sweden). All main antibodies were purchased from Eprodisate Sodium Genetex (Hsinchu, Taiwan) and anti-mouse, and anti-rabbit secondary antibodies were purchased from Rabbit Polyclonal to SEMA4A GE Healthcare (Uppsala, Sweden). All the chemicals and biochemicals used in this study were of analytical grade. == Cell lines and cell culture == The rat cardiomyocyte cell collection H9C2 was purchased from American Type Culture Collection (ATCC) (Manassas, VA) and was managed in Dulbeccos altered Eagles medium (DMEM) supplemented with 10% (v/v) FCS, L-glutamine (2 mM), streptomycin Eprodisate Sodium (100 g/mL) and penicillin (100 IU/mL) (all from Gibco-Invitrogen Corp., UK). Cells were incubated in a humidified incubator at 37C and 5% CO2. and passaged at 80-90% confluence by trypsinization according to standard procedures. == MTT cell viability assay == The detailed MTT experimental process has been explained in our previous study [19]. == Immunofluorescence == Cells were plated onto coverslips (VWR international) for.