RESUMO
Lanatoside C has a promising anti-tumor activity and is a potential candidate for radiosensitizers. In this study, we have investigated the therapeutic efficacy of the combination of 131I-trastuzumab and lanatoside C for inhibition of human epidermal growth factor receptor 2 (HER2) positive tumor progression in NCI-N87 xenograft model. The combination treatment (131I-trastuzumab and lanatoside C) showed highest cytotoxicity when compared to non-treated control or trastuzumab alone or 131I alone or 131I-trastuzumab alone in vitro. Biodistribution studies using 131I-trastuzumab or combination of 131I-trastuzumab and lanatoside C showed tumor uptake in BALB/c nude mice bearing HER2 positive NCI-N87 tumor xenograft model. The higher tumor uptake was observed in 131I-trastuzumab (19.40 ± 0.04% ID/g) than in the combination of 131I-trastuzumab and lanatoside C (14.02 ± 0.02% ID/g) at 24 h post-injection. Most importantly, an antitumor effect was observed in mice that received the combination of 131I-trastuzumab and lanatoside C (p = 0.009) when compared to control. In addition, mice received lanatoside C alone (p = 0.085) or 131I-trastuzumab alone (p = 0.160) did not significantly inhibit tumor progression compared with control. Taken together, our data suggest that combination of 131I-trastuzumab and lanatoside C might be a potential synergistic treatment for radioimmunotherapy to control the HER2 positive tumor.
Assuntos
Radioisótopos do Iodo/administração & dosagem , Lanatosídeos/farmacologia , Neoplasias/etiologia , Neoplasias/terapia , Radioimunoterapia , Receptor ErbB-2/metabolismo , Trastuzumab/farmacologia , Animais , Linhagem Celular Tumoral , Modelos Animais de Doenças , Sinergismo Farmacológico , Humanos , Radioisótopos do Iodo/química , Lanatosídeos/química , Camundongos , Neoplasias/metabolismo , Radioimunoterapia/métodos , Receptor ErbB-2/genética , Distribuição Tecidual , Trastuzumab/química , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Recent studies have revealed that cardiac glycosides, such as digitalis and digoxin, have anticancer activity and may serve as lead compounds for the development of cancer treatments. The poor prognosis of hepatocellular carcinoma (HCC) patients reflects the development of resistance to current chemotherapeutic agents, highlighting the need for discovering new small-molecule therapeutics. Here, we found that lanatoside C, an anti-arrhythmic agent extracted from Digitalis lanata, inhibited the growth of HCC cells and dramatically decreased tumor volume as well as delayed tumor growth without obvious body weight loss. Moreover, lanatoside C triggered mitochondrial membrane potential (MMP) loss, activation of caspases and translocation of apoptosis-inducing factor (AIF) into the nucleus, which suggests that lanatoside C induced apoptosis through both caspase-dependent and -independent pathways. Furthermore, we discovered that lanatoside C activated protein kinase delta (PKCδ) via Thr505 phosphorylation and subsequent membrane translocation. Inhibition of PKCδ reversed lanatoside C-induced MMP loss and apoptosis, confirming that lanatoside C caused apoptosis through PKCδ activation. We also found that the AKT/mTOR pathway was negatively regulated by lanatoside C through PKCδ activation. In conclusion, we provide the first demonstration that the anticancer effects of lanatoside C are mainly attributable to PKCδ activation.
Assuntos
Apoptose/efeitos dos fármacos , Carcinoma Hepatocelular/enzimologia , Carcinoma Hepatocelular/patologia , Glicosídeos Cardíacos/farmacologia , Lanatosídeos/farmacologia , Neoplasias Hepáticas/enzimologia , Neoplasias Hepáticas/patologia , Proteína Quinase C-delta/metabolismo , Animais , Glicosídeos Cardíacos/química , Caspases/metabolismo , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Humanos , Lanatosídeos/química , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos SCID , Proteínas Mitocondriais/metabolismo , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Modelos Biológicos , Fosforilação/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Acylation of lanatoside C in the presence of organocatalyst 5 gave the C(4'''')-O-acylate in up to 90% regioselectivity (catalyst-controlled regioselectivity). Various functionalized acyl groups can be introduced at the C(4'''')-OH by a mixed anhydride method in the presence of 5 or the related organocatalyst. On the other hand, DMAP-catalyzed acylation of lanatoside C gave the C(3'''')-O-acylate in up to 97% regioselectivity (substrate-controlled regioselectivity). Thus, diverse regioselective introduction of acyl groups among eight free hydroxy groups of lanatoside C was achieved.
Assuntos
Glicosídeos Cardíacos/química , Lanatosídeos/química , Lanatosídeos/síntese química , Acilação , Catálise , EstereoisomerismoRESUMO
Recent reports have provided the first insights into the mechanisms of the extensive post-translational modifications involved in the biosynthesis of the lantibiotics, a class of peptide antimicrobial agents. These modifications involve dehydration of several serine and threonine residues followed by intramolecular conjugate additions of cysteines, resulting in extensively cross-linked polycyclic structures. Both in vivo and in vitro studies indicate low substrate specificity of the modification machinery, which has been explored for re-engineering of the structures of a number of members. In addition to these developments in understanding their biosynthesis, studies on the mode of action of several lantibiotics have shown a unique mechanism of binding to lipid II, an intermediate in cell wall biosynthesis.
Assuntos
Antibacterianos/metabolismo , Peptídeos/metabolismo , Processamento de Proteína Pós-Traducional , Sequência de Aminoácidos , Bacteriocinas , Parede Celular/metabolismo , Cisteína/química , Cisteína/metabolismo , Lanatosídeos/química , Lanatosídeos/metabolismo , Metabolismo dos Lipídeos , Dados de Sequência Molecular , Serina/química , Serina/metabolismo , Especificidade por Substrato , Treonina/química , Treonina/metabolismoRESUMO
An analytical method for the determination of cardiac glycosides in Digitalis purpurea leaves by hplc was developed. Quantitation was carried out by the incorporation of lanatoside A as an internal standard. The present method is sufficiently precise and relatively simple.
