Heat Shock Protein 20 Interacting With Phosphorylated Akt Reduces Doxorubicin-Triggered Oxidative Stress and Cardiotoxicity

Abstract

Abstract-Doxorubicin (DOX) is a widely used antitumor drug, but its application is limited because of its cardiotoxic side effects. Heat shock protein (Hsp)20 has been recently shown to protect cardiomyocytes against apoptosis, induced by ischemia/reperfusion injury or by prolonged ␤-agonist stimulation. However, it is not clear whether Hsp20 would exert similar protective effects against DOX-induced cardiac injury. Actually, DOX treatment was associated with downregulation of Hsp20 in the heart. To elucidate the role of Hsp20 in DOX-triggered cardiac toxicity, Hsp20 was first overexpressed ex vivo by adenovirus-mediated gene delivery. Increased Hsp20 levels conferred higher resistance to DOX-induced cell death, compared to green fluorescent protein control. Furthermore, cardiac-specific overexpression of Hsp20 in vivo significantly ameliorated acute DOX-triggered cardiomyocyte apoptosis and animal mortality. Hsp20 transgenic mice also showed improved cardiac function and prolonged survival after chronic administration of DOX. The mechanisms underlying these beneficial effects were associated with preserved Akt phosphorylation/activity and attenuation of DOX-induced oxidative stress. Coimmunoprecipitation studies revealed an interaction between Hsp20 and phosphorylated Akt. Accordingly, BAD phosphorylation was preserved, and cleaved caspase-3 was decreased in DOX-treated Hsp20 transgenic hearts, consistent with the antiapoptotic effects of Hsp20. Parallel ex vivo experiments showed that either infection with a dominant-negative Akt adenovirus or preincubation of cardiomyocytes with the phosphatidylinositol 3-kinase inhibitors significantly attenuated the protective effects of Hsp20. Taken together, our findings indicate that overexpression of Hsp20 inhibits DOX-triggered cardiac injury, and these beneficial effects appear to be dependent on Akt activation. Thus, Hsp20 may constitute a new therapeutic target in ameliorating the cardiotoxic effects of DOX treatment in cancer patients. (Circ Res. 2008;103:1270-1279.)

Hamartin-Hsp70 Interaction Is Necessary for Akt-Dependent Tuberin Phosphorylation during Heat Shock

“…Hsp families have been found to be phosphorylated by tyrosine, serine, and threonine kinases. 24,25) Since hamartin-tuberin complex is controlled under the regulation of an insulin/Akt signal, 17) we also suggest that the activity of hamartin-Hsp70 complex during Akt-dependent tuberin phosphorylation is not a heat shock-specific event but rather a general control, since we observed the same results after insulin stimulation (Supplemental Fig. 1; see Biosci.…”

Phosphorylation of AktSer473/Ask1Ser83 in Trolox-induced suppression of doxorubicin-induced changes in rat cardiomyocytes

“…The antioxidant Trolox is readily available to cardiomyocytes under in vitro conditions and, thus, is able to efficiently scavenge free radicals. Furthermore, increased OS has been implicated in the process of apoptosis in the cardiomyocytes under multiple stress conditions (37)(38)(39)(40). In the current study, we report that Trolox induces a decrease in apoptotic proteins (PARP, caspase 3, Bax) and an increase in antiapoptotic protein (Bcl-xL).…”

“…Akt gene transfer in the heart has also been shown to ameliorate Dox-induced contractile dysfunction (38). Akt-induced Ask1 inhibition has also been supported by the studies of heat shock proteins (21,40). Similar to Trolox, selenite-induced suppression of Ask1/JNK through the activation of PI3K/Akt pathway during reperfusion has also been reported (44).…”

Role of heat shock factor-1 activation in the doxorubicin-induced heart failure in mice

“…In another study, ERK activation and upregulation of Hsp60 in Dox-treated rat hearts were found to protect the heart against ischemia-reperfusion injury (25). However, none of these studies have revealed the role of HSF-1 activation and dynamic induction of Hsp25 in Dox-treated hearts, as a response to the oxidative stress, although in a recent study Hsp20 has been found to increase in mouse hearts upon treatment with Dox (9). The present study is the first to demonstrate a link between HSF-1 activation and Dox-induced heart failure and that Hsp25 could be triggering a signaling cascade causing the loss of cardiomyocytes.…”