Cardiotoxicity by doxorubicin hampers its therapeutic potential as an anticancer drug, but mechanisms leading to cardiotoxicity remain contentious. Through this study, the functional contribution of insulin-like growth factor receptor type II α (IGF-IIRα) which is a novel stress-inducible protein was explored in doxorubicin-induced cardiac stress. Employing both in vitro H9c2 cells and in vivo transgenic rat models (SD-TG [IGF-IIRα]) overexpressing IGF-IIRα specifically in heart, we found that IGF-IIRα leads to cardiac structural abnormalities and functional perturbations that were severely aggravated by doxorubicin-induced cardiac stress. Overexpression of IGF-IIRα leads to cumulative elevation of stress associated cardiac hypertrophy and apoptosis factors. There was a significant reduction of survival associated proteins p-Akt and estrogen receptor β/α, and abnormal elevation of cardiac hypertrophy markers such as atrial natriuretic peptide, cardiac troponin-I, and apoptosis-inducing agents such as p53, Bax, and cytochrome C, respectively. IGF-IIRα also altered the expressions of AT1R, ERK1/2, and p38 proteins. Besides, IGF-IIRα also increased the reactive oxygen species production in H9c2 cells which were markedly aggravated by doxorubicin treatment. Together, we showed that IGF-IIRα is a novel stress-induced protein that perturbed cardiac homeostasis and cumulatively exacerbated the doxorubicin-induced cardiac injury that perturbed heart functions and ensuing cardiomyopathy.
Keywords: Bax; IGF-IIRα; cardiotoxicity; doxorubicin; p53; transgenic rats.
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