RESUMEN
Therapeutic applications of microRNAs (miRNAs) in chemotherapy were confirmed to be valuable, but there is rare to identify their specific roles and functions in shikonin treatment toward tumors. Here, for the first time, we reported that miR-143 played a critical role in the antitumor activity of shikonin in glioblastoma stem cells (GSCs). The results showed that the expression of miR-143 was downregulated in shikonin treated GSCs within 24 h. MiR-143 overexpression significantly enhanced the inhibitory effect of shikonin toward GSCs on cell viability. Besides, miR-143 overexpression caused a significant increase in the apoptotic fraction and made apoptosis occur earlier. Further investigation identified that BAG3, an apoptotic regulator, was a functional target of miR-143 in shikonin treated GSCs. The expression of BAG3 was upregulated in shikonin treated GSCs within 24 h. MiR-143 overexpression significantly reversed the high expression of BAG3 in shikonin treated GSCs. Moreover, it was confirmed that the enhanced cytotoxicity of shikonin by miR-143 overexpression was reversed by BAG3 overexpression both in vitro and in vivo, suggesting that the enhanced tumor suppressive effects by miR-143 overexpression was at least partly through the regulation of BAG3. Taken together, for the first time, our results demonstrate that miR-143 could enhance the antitumor activity of shikonin toward GSCs through reducing BAG3 expression, which may provide a novel therapeutic strategy for enhancing the treatment efficacy of shikonin toward GSCs.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/genética , Antineoplásicos Fitogénicos/uso terapéutico , Proteínas Reguladoras de la Apoptosis/genética , Medicamentos Herbarios Chinos/uso terapéutico , Glioblastoma/tratamiento farmacológico , MicroARNs/genética , Naftoquinonas/uso terapéutico , Células Madre Neoplásicas/efectos de los fármacos , Animales , Regulación hacia Abajo/efectos de los fármacos , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Glioblastoma/genética , Glioblastoma/patología , Humanos , Masculino , Ratones Desnudos , Células Madre Neoplásicas/metabolismo , Células Madre Neoplásicas/patología , Células Tumorales Cultivadas , Regulación hacia Arriba/efectos de los fármacosRESUMEN
Though previous study demonstrated that shikonin could exert its antitumor activity by inducing apoptosis and necrosis, the pro-survival mechanisms involved in its antitumor process are still little to know. In the present study, for the first time, we found a protective mechanism was simultaneously activated which caused the reduced sensitivity of glioblastoma stem cells (GSCs) to the cytotoxicity of shikonin. Reduced active caspase-9 expression and enhanced mitochondrial membrane potential (MMP) were intriguingly observed within 24 h treatment by shikonin in GSCs. Further investigation identified that Endoplasmic Reticulum Stress (ERS) was involved in its antitumor process, which compromised the cytotoxicity of shikonin toward GSCs. Inhibiting ERS by 4-phenylbutyric acid (4-PBA) markedly enhanced the cytotoxicity of shikonin in GSCs. The consistent result was simultaneously observed in the GSCs-xenografted mice. Furthermore, our results identified that JNK/c-Jun pathway was involved in the antitumor process of shikonin, providing a mechanism by which ERS reduced the cytotoxicity of shikonin toward GSCs. Altogether, the novel observation in the present study identified that inhibiting ERS would be an attractive new approach to enhance the therapeutic potency of shikonin toward GSCs.