RESUMO
BACKGROUND: Cyclin-dependent kinases (CDKs) control cell cycle progression, RNA transcription and apoptosis, making them attractive targets for anticancer drug development. Unfortunately, CDK inhibitors developed to date have demonstrated variable efficacy. METHODS: We generated drug-resistant cells by continuous low-dose exposure to a model pyrazolo[1,5-a]pyrimidine CDK inhibitor and investigated potential structural alterations for optimal efficacy. RESULTS: We identified induction of the ATP-binding cassette (ABC) transporters, ABCB1 and ABCG2, in resistant cells. Assessment of features involved in the ABC transporter substrate specificity from a compound library revealed high polar surface area (>100 Å(2)) as a key determinant of transporter interaction. We developed ICEC-0782 that preferentially inhibited CDK2, CDK7 and CDK9 in the nanomolar range. The compound inhibited phosphorylation of CDK substrates and downregulated the short-lived proteins, Mcl-1 and cyclin D1. ICEC-0782 induced G2/M arrest and apoptosis. The permeability and cytotoxicity of ICEC-0782 were unaffected by ABC transporter expression. Following daily oral dosing, the compound inhibited growth of human colon HCT-116 and human breast MCF7 tumour xenografts in vivo by 84% and 94%, respectively. CONCLUSION: We identified a promising pyrazolo[1,5-a]pyrimidine compound devoid of ABC transporter interaction, highly suitable for further preclinical and clinical evaluation for the treatment of cancer.
Assuntos
Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Transportadores de Cassetes de Ligação de ATP/metabolismo , Quinases Ciclina-Dependentes/antagonistas & inibidores , Proteínas de Neoplasias/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Subfamília B de Transportador de Cassetes de Ligação de ATP , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/genética , Membro 2 da Subfamília G de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Pontos de Checagem do Ciclo Celular/genética , Divisão Celular/efeitos dos fármacos , Divisão Celular/genética , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular/efeitos dos fármacos , Permeabilidade da Membrana Celular/genética , Ciclina D1/genética , Quinases Ciclina-Dependentes/metabolismo , Regulação para Baixo/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos , Feminino , Fase G2/efeitos dos fármacos , Fase G2/genética , Células HCT116 , Humanos , Células MCF-7 , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Proteína de Sequência 1 de Leucemia de Células Mieloides/genética , Proteínas de Neoplasias/genética , Fosforilação/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacocinética , Pirimidinas/farmacocinética , Pirimidinas/farmacologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
A stimulation of collateral vessel growth is an attractive alternative therapeutic tool especially for patients with diffuse occlusive vessel disease. Extensive in vivo and in vitro studies in the preceding decades have led us to a thorough understanding of basic arteriogenic principles. Due to the timeline of naturally occurring arteriogenesis, a well-timed therapeutic induction appears to be limiting for effective proarteriogenic therapies in high-risk patients. Potential therapeutic approaches are based on a stimulation of monocyte function through cytokine application. First clinical studies have, nevertheless, demonstrated the limits of a unifactorial therapy. Therefore, a stimulation of the mechanical inductor of arteriogenic proliferation, i. e. fluid shear stress acting on the arteriolar endothelium, appears as a feasible therapeutic addition. Current results show the feasibility of that principle not only through active physical training, but also through passive application of an external counterpulsation (EECP), a method showing promising first results in the clinical setting.