RESUMO
Oncogenic BRAF alleles are both necessary and sufficient for cellular transformation, suggesting that chemical inhibition of the activated mutant protein kinase may reverse the tumor phenotype. Here, we report the characterization of SB-590885, a novel triarylimidazole that selectively inhibits Raf kinases with more potency towards B-Raf than c-Raf. Crystallographic analysis revealed that SB-590885 stabilizes the oncogenic B-Raf kinase domain in an active configuration, which is distinct from the previously reported mechanism of action of the multi-kinase inhibitor, BAY43-9006. Malignant cells expressing oncogenic B-Raf show selective inhibition of mitogen-activated protein kinase activation, proliferation, transformation, and tumorigenicity when exposed to SB-590885, whereas other cancer cell lines and normal cells display variable sensitivities or resistance to similar treatment. These studies support the validation of oncogenic B-Raf as a target for cancer therapy and provide the first evidence of a correlation between the expression of oncogenic BRAF alleles and a positive response to a selective B-Raf inhibitor.
Assuntos
Imidazóis/uso terapêutico , Neoplasias/tratamento farmacológico , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , Alelos , Animais , Western Blotting , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Cristalização , Cristalografia por Raios X , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Feminino , Células HT29 , Humanos , Imidazóis/química , Camundongos , Camundongos Nus , Modelos Moleculares , Estrutura Molecular , Mutação/genética , Neoplasias/enzimologia , Neoplasias/patologia , Fosforilação/efeitos dos fármacos , Conformação Proteica/efeitos dos fármacos , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Proto-Oncogênicas B-raf/química , Proteínas Proto-Oncogênicas B-raf/genética , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
During our effort to develop dual VEGFR2 and Tie-2 inhibitors as anti-angiogenic agents for cancer therapy, we discovered 4-amino-5-(4-((2-fluoro-5-(trifluoromethyl)phenyl)- aminocarbonylamino)phenyl)furo[2,3-d]pyrimidine (8a) possessing strong inhibitory activity at both the enzyme and cellular level against VEGFR2 and Tie-2. Compound 8a demonstrated high pharmacokinetic exposure through oral administration, and showed marked tumor growth inhibition and anti-angiogenic activity in mouse HT-29 xenograft model via once-daily oral administration.