RESUMO
The link of hedgehog (Hh) signaling activation to human cancer and synthesis of a variety of Hh signaling inhibitors raise great expectation that inhibiting Hh signaling may be effective in human cancer treatment. Cyclopamine (Cyc), an alkaloid from the Veratrum plant, is a specific natural product inhibitor of the Hh pathway that acts by targeting smoothened (SMO) protein. However, its poor solubility, acid sensitivity, and weak potency relative to other Hh antagonists prevent the clinical development of Cyc as a therapeutic agent. Here, we report properties of cyclopamine tartrate salt (CycT) and its activities in Hh signaling-mediated cancer in vitro and in vivo. Unlike Cyc, CycT is water soluble (5-10 mg/mL). The median lethal dose (LD50) of CycT was 62.5 mg/kg body weight compared to 43.5 mg/kg for Cyc, and the plasma half-life (T1/2) of CycT was not significantly different from that of Cyc. We showed that CycT had a higher inhibitory activity for Hh signaling-dependent motor neuron differentiation than did Cyc (IC50 = 50 nmol/L for CycT vs. 300 nmol/L for Cyc). We also tested the antitumor effectiveness of these Hh inhibitors using two mouse models of basal cell carcinomas (K14cre:Ptch1(neo/neo) and K14cre:SmoM2(YFP)). After topical application of CycT or Cyc daily for 21 days, we found that all CycT-treated mice had tumor shrinkage and decreased expression of Hh target genes. Taken together, we found that CycT is an effective inhibitor of Hh signaling-mediated carcinogenesis.
Assuntos
Carcinoma Basocelular/patologia , Proteínas Hedgehog/metabolismo , Transdução de Sinais , Neoplasias Cutâneas/patologia , Carga Tumoral/efeitos dos fármacos , Alcaloides de Veratrum/farmacologia , Animais , Diferenciação Celular/efeitos dos fármacos , Células-Tronco Embrionárias/citologia , Proteínas Hedgehog/antagonistas & inibidores , Camundongos , Neurônios Motores/citologia , Plantas Medicinais/química , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais/efeitos dos fármacos , Receptor Smoothened , Solubilidade , Tartaratos/sangue , Tartaratos/farmacologia , Veratrum/química , Alcaloides de Veratrum/sangue , Alcaloides de Veratrum/isolamento & purificaçãoRESUMO
A diversity-oriented synthesis has been developed for facile construction of a library of carbohydrate-cyclopamine conjugates. The synthetic protocol is suitable for generating cyclopamine derivatives with various structural motifs for exploring the desired activity. From this initial library, we have observed one derivative that exhibits improved activity against lung cancer cell as compared to cyclopamine.
