ICRF-187 as a cardioprotectant in children treated with anthracyclines

Procyanidins produce significant attenuation of doxorubicin-induced cardiotoxicity via suppression of oxidative stress

Doxorubicin is widely prescribed in the chemotherapy of haematological malignancies and solid tumours. The major side effect of doxorubicin is oxidative injury-related cardiotoxicity, which has dramatically hindered its usage. Procyanidins from grape seeds are potent free radical scavengers that have been shown to protect against anthracycline-induced cardiotoxicity. In the present study, we tested whether procyanidins would prevent the doxorubicin-induced cardiotoxicity in rats. Rats were intraperitoneally treated with doxorubicin at a cumulative dose of 15 mg/kg with and without pre-administration of procyanidins. Our data showed that doxorubicin led to cardiac function deterioration, myocardial injury and increased oxidative stress in cardiac tissues. The cardiac function deterioration by doxorubicin included increased QT-interval and ST-interval in electrocardiograph (ECG) and decreased left ventricular developed pressure. Doxorubicin-induced myocardial injury was shown by the increased creatine kinase, alanine aminotransferase and aspartate aminotransferase in serum as well as in myocardial lesions. Pretreatment with procyanidin (150 mg/kg daily) effectively hindered the adverse effects of doxorubicin, such as myocardial injury and impaired heart function. Procyanidin pretreatment attenuated cytoplasmic vacuolization, increased left ventricular developed pressure and improved the ECG. The cardioprotective effect of procyanidin corresponded to the decrease of lipid peroxidation and the increase of cardiac antioxidant potency in doxorubicin-treated rats that were also given procyanidin. An in vitro cytotoxic study showed that procyanidins did not attenuate the antineoplastic activity of doxorubicin to A549 adenocarcinoma cells. All the above lines of evidence suggest that procyanidins protect cardiomyocytes from doxorubicin-induced cardiotoxicity via suppression of oxidative stress.

Ketotifen reverses MDR1-mediated multidrug resistance in human breast cancer cells in vitro and alleviates cardiotoxicity induced by doxorubicin in vivo

PURPOSE

To investigate the effect of the antihistamine ketotifen on multidrug resistance in human breast cancer cells and doxorubicin toxicity in mice.

METHODS

Clonogenicity assays were used to test the effect of ketotifen on human multidrug resistant breast cancer cell lines exposed to chemotherapeutic agents. Flow cytometry was used to measure accumulation of doxorubicin in cells. Fluorimetry was used to measure accumulation of doxorubicin in cardiac tissues. Histological analysis and toxicity studies in mice were used to test the effect of ketotifen on doxorubicin-induced toxicity.

RESULTS

Ketotifen was found to restore the sensitivity of P-glycoprotein-overexpressing multidrug-resistant MCF-7/adr cells to doxorubicin, mitoxantrone, VP-16 and vinblastine, but not to methotrexate or camptothecin. Ketotifen, however, was unable to restore sensitivity of BCRP-overexpressing MCF-7/mx cells or MRP-overexpressing MCF-7/vp cells to mitoxantrone or VP-16, respectively. In vivo, pretreatment of mice with ketotifen caused an increased accumulation of doxorubicin in cardiac tissue, consistent with a block in drug clearance. However, unlike verapamil, ketotifen pretreatment did not enhance doxorubicin toxicity but in fact provided protection, both at the level of cardiac tissue damage and in terms of survival.

CONCLUSIONS

Taken together, these observations show that ketotifen is unique in its ability both to reverse multidrug resistance due to P-glycoprotein overexpression and to provide cardioprotection to doxorubicin.

Molecular basis of anthracycline-induced cardiotoxicity and its prevention

Anthracyclines are a class of highly potent antitumor antibiotics utilized against hematologic and solid tumors in children and in adults. Their use has been limited primarily by their cardiotoxic side effects, which may lead to congestive heart failure. Although there is a linear relationship between the cumulative dose received and the incidence of cardiotoxicity, in some patients cardiotoxicity may develop at doses below the generally accepted threshold level. Anthracycline-induced cardiotoxicity is believed to be related to the generation of highly reactive oxygen species, which, by means of membrane lipid peroxidation, cause direct damage to cardiac myocyte membranes. Another important factor may be the relatively poor antioxidant defense system of the heart. In an attempt to circumvent these toxic effects, a wide variety of antioxidants have been used in cell culture, animal, and human studies without consistent beneficial effects. Moreover, none of the agents used to date are designed to act selectively upon the heart. If the cardiac complications resulting from anthracyclines could be reduced and/or prevented, higher doses could potentially be used, thereby increasing cancer cure rates. Furthermore, the incidence of cardiac toxicity resulting in congestive heart failure or even heart transplantation would be reduced, therefore increasing the quality and extent of life for cancer survivors. This article will review the basic science of free radical biology, the biology of oxygen-derived free radicals and antioxidant proteins, and explore some new and innovative approaches to limiting and/or preventing anthracycline-induced cardiotoxicity.