RESUMO
AIMS: The clinical use of doxorubicin for the treatment of cancer is limited by its cardiotoxicity. Flavaglines are natural products that have both potent anticancer and cardioprotective properties. A synthetic analog of flavaglines, FL3, efficiently protects mice from the cardiotoxicity of doxorubicin. The mechanism underlying this cardioprotective effect has yet to be elucidated. METHODS AND RESULTS: Here, we show that FL3 binds to the scaffold proteins prohibitins (PHBs) and thus promotes their translocation to mitochondria in the H9c2 cardiomyocytes. FL3 induces heterodimerization of PHB1 with STAT3, thereby ensuring cardioprotection from doxorubicin toxicity. This interaction is associated with phosphorylation of STAT3. A JAK2 inhibitor, WP1066, suppresses both the phosphorylation of STAT3 and the protective effect of FL3 in cardiomyocytes. The involvement of PHBs in the FL3-mediated cardioprotection was confirmed by means of small interfering RNAs (siRNAs) targeting PHB1 and PHB2. The siRNA knockdown of PHBs inhibits both phosphorylation of STAT3 and the cardioprotective effect of FL3. CONCLUSION: Activation of mitochondrial STAT3/PHB1 complex by PHB ligands may be a new strategy against doxorubicin-induced cardiotoxicity and possibly other cardiac problems.
Assuntos
Benzofuranos/farmacologia , Cardiotônicos/farmacologia , Doxorrubicina/farmacologia , Miócitos Cardíacos/efeitos dos fármacos , Proteínas Repressoras/metabolismo , Fator de Transcrição STAT3/metabolismo , Animais , Antibióticos Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Western Blotting , Cardiotoxicidade , Células Cultivadas , Técnicas Imunoenzimáticas , Imunoprecipitação , Ligantes , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Fosforilação/efeitos dos fármacos , Proibitinas , RNA Interferente Pequeno/genética , Ratos , Proteínas Repressoras/antagonistas & inibidores , Proteínas Repressoras/genética , Fator de Transcrição STAT3/antagonistas & inibidores , Fator de Transcrição STAT3/genéticaRESUMO
In breast cancer cells, the neurotrophin receptor p75(NTR) acts as a prosurvival factor able to stimulate resistance to apoptosis, but its mechanism of action remains incompletely defined. In this study, we investigated the global proteome modification induced by p75(NTR) overexpression in breast cancer cells treated by the pro-apoptotic agent tumor necrosis factor (TNF)-related-apoptosis-inducing-ligand (TRAIL). p75(NTR) was stably overexpressed in the MCF-7 breast cancer cells and the impact of a treatment by TRAIL was investigated in wild type vs. p75(NTR) overexpressing cells. Proteins were separated in two-dimensional electrophoresis, and regulated spots were detected by computer assisted analysis before identification by MALDI-TOF/TOF mass spectrometry. In the absence of TRAIL treatment, p75(NTR) did not induce any change in the proteome of breast cancer cells. In contrast, after treatment with TRAIL, fragments of cytokeratin-8, -18 and -19, as well as full length cytokeratin-18, were up-regulated by p75(NTR) overexpression. Of note, spectrin alpha-chain and the ribosomal protein RPLP0 were induced by TRAIL, independently of p75(NTR) level. Interestingly, the well known stress-induced protein HSP-27 was less abundant when p75(NTR) was overexpressed, indicating that p75(NTR) overexpression reduced TRAIL induced cell stress. These data indicate that overexpression of p75(NTR) induces proteome modifications in breast cancer cells and provide information on how this receptor contributes in tumor cell resistance to apoptosis.
