Key result
Doxorubicin inhibited AMPK activation, increased cell death, and induced robust p53 accumulation in mouse embryonic fibroblasts and cardiomyocytes.
Doxorubicin-induced cell death and genotoxic stress are mediated by AMPK inhibition and subsequent SIRT1 dysfunction and p53 accumulation, suggesting AMPK activation as a potential cardioprotective strategy.
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Doxorubicin may promote cardiomyocyte death via AMPK inhibition in mice; leaves open whether AMPK activation protects human hearts.
Doxorubicin, an anthracycline antibiotic, is widely used in cancer treatment. Doxorubicin produces genotoxic stress and p53 activation in both carcinoma and non-carcinoma cells. Although its side effects in non-carcinoma cells, especially in heart tissue, are well known, the molecular targets of doxorubicin are poorly characterized. Here, we report that doxorubicin inhibits AMP-activated protein kinase (AMPK) resulting in SIRT1 dysfunction and p53 accumulation. Spontaneously immortalized mouse embryonic fibroblasts (MEFs) or H9C2 cardiomyocyte were exposed to doxorubicin at different doses and durations. Cell death and p53, SIRT1, and AMPK levels were examined by Western blot. In MEFs, doxorubicin inhibited AMPK activation, increased cell death, and induced robust p53 accumulation. Genetic deletion of AMPKα1 reduced NAD(+) levels and SIRT1 activity and significantly increased the levels of p53 and cell death. Pre-activation of AMPK by 5-aminoimidazole-4-carboxamide ribonucleoside or transfection with an adenovirus encoding a constitutively active AMPK (AMPK-CA) markedly reduced the effects of doxorubicin in MEFs from Ampkα1 knock-out mice. Conversely, pre-inhibition of Ampk further sensitized MEFs to doxorubicin-induced cell death. Genetic knockdown of p53 protected both wild-type and Ampkα1(-/-) MEFs from doxorubicin-induced cell death. p53 accumulation in Ampkα1(-/-) MEFs was reversed by SIRT1 activation by resveratrol. Taken together, these data suggest that AMPK inhibition by doxorubicin causes p53 accumulation and SIRT1 dysfunction in MEFs and further suggest that pharmacological activation of AMPK might alleviate the side effects of doxorubicin.
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Wang et al. (2012) studied Doxorubicin-induced genotoxic stress and cell death. Doxorubicin was evaluated on Cell death, p53, SIRT1, and AMPK levels. Doxorubicin inhibited AMPK activation, increased cell death, and induced robust p53 accumulation in mouse embryonic fibroblasts and cardiomyocytes.
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