Febuxostat ameliorates doxorubicin-induced cardiotoxicity in rats
Introduction
Doxorubicin, an anthracycline antibiotic, has a broad spectrum of anti-neoplastic activity [1], [2]. Nevertheless, its clinical use is complicated by dose limiting cardiotoxicity [3], [4]. Depending upon the duration required for its clinical manifestation, the cardiotoxicity due to doxorubicin may be acute, presenting within 2–3 days of administration; or chronic, which clinically presents as dilated cardiomyopathy, usually within 30 days of administration [1].
The free radical generating properties of anthracycline antibiotics have been well documented. A 98% increase in reactive oxygen species generation has been reported during treatment of isolated rat cardiomyocytes with doxorubicin [5]. Sinha and co-workers have proposed that the chemical structure of doxorubicin is prone to generation of free radicals [6]. They also demonstrated the formation of hydroxyl radicals when doxorubicin was used to treat patients with breast cancer. In fact, Rosen and Halpern also demonstrated the presence of free radicals by spin trapping in patients receiving doxorubicin and established a correlation between the level of free radicals and the degree and severity of cellular injury [7]. Xanthine oxidase is an endogenous enzyme that is responsible for catabolism of purines by oxidizing hypoxanthine to xanthine and ultimately to uric acid, and produces free radicals during this reaction, thus contributing to oxidative stress. Doxorubicin has been shown to enhance the activity of xanthine oxidase, which is considered as one of the mechanisms responsible for the generation of free radicals on administration of doxorubicin [8], [9].
Previously conducted studies on rats have successfully demonstrated that allopurinol prevents cardiotoxicity due to doxorubicin via decreasing production of free radicals as a consequence of xanthine oxidase inhibition [10]. Similarly, in dilated cardiomyopathic hamsters, xanthine oxidase inhibition with allopurinol has been shown to attenuate left ventricular remodeling and dysfunction consequent to inhibition of oxidative stress [11]. Moreover, it has been reported that inhibition of xanthine oxidase activity in patients with congestive heart failure significantly improves left ventricular ejection fraction [12].
Febuxostat is a novel xanthine oxidase inhibitor that is now therapeutically employed as a promising alternative to allopurinol for chemotherapy-induced hyperuricemia [13]. In comparison to allopurinol, febuxostat is more efficacious, is associated with fewer significant side effects and dose adjustment is not necessary in patients with decreased renal function. Due to its xanthine oxidase inhibition, febuxostat can potentially exert additional protection against doxorubicin-induced cardiotoxicity [14], [15], [16]. Therefore, the objective of our study was to evaluate the effect of febuxostat in an animal model of doxorubicin cardiomyopathy and compare it with carvedilol, a well-known anti-oxidant with significant positive outcomes in various pre-clinical and clinical studies of doxorubicin-induced cardiomyopathy [17], [18], [19], [20].
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Animals
Adult male albino Wistar rats, 10 to 12 weeks old, weighing 150 to 200 g, were procured from the Central Animal Facility, All India Institute of Medical Sciences, New Delhi. The study protocol was reviewed and approved by the Institutional Animal Ethics Committee, All India Institute of Medical Sciences, New Delhi (611/IAEC/2011) and conformed to the Indian National Science Academy (INSA) Guidelines for the use and care of experimental animals in research. The rats were housed in polypropylene
Evaluation of hemodynamic parameters
The administration of doxorubicin led to a significant (P < 0.001) fall in SAP, DAP and MAP as compared to control group (Fig. 2A–C). Febuxostat and carvedilol significantly normalized the arterial pressures as compared to doxorubicin treated rats.
Doxorubicin also significantly (P < 0.001) reduced +LVdP/dtmax and −LVdP/dtmax as compared to the control group; which was significantly ameliorated by febuxostat and carvedilol (Fig. 2D and E).
Moreover, doxorubicin administration also elevated (P < 0.001)
Discussion
This study, first of its kind, demonstrated that febuxostat ameliorated myocardial dysfunction in doxorubicin-challenged rats through improvement in body weight and myocardial architecture, augmentation of antioxidant status and a reduction in cardiac injury markers and fibrosis. Moreover, the expression of inflammatory and apoptotic proteins were also reduced. These findings corroborate the earlier findings with carvedilol [17].
As observed in our study, doxorubicin administration caused a
Conflict of Interest
The authors declare no competing interests.
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Acknowledgements
The authors gratefully acknowledge Mr. Deepak and Mr. BM Sharma for their technical assistance during the course of the surgery and in the preparation of histopathological slides and the Department of Science and Technology, Govt. of India for providing fellowship to Saurabh Bharti (IF10332) and Neha Rani (IF120584) under the INSPIRE-DST-Fellowship programme. We also duly acknowledge the assistance provided by the Sophisticated Analytical Instrumentation Facility (SAIF), AIIMS, New Delhi.
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Authors contributed equally to the work.