RESUMO
In this Letter we describe the optimization of an aminopurine lead (1) with modest potency and poor overall kinase selectivity which led to the identification of a series of potent, selective JNK inhibitors. Improvement in kinase selectivity was enabled by introduction of an aliphatic side chain at the C-2 position. CC-359 (2) was selected as a potential clinical candidate for diseases manifested by ischemia reperfusion injury.
Assuntos
2-Aminopurina/química , 2-Aminopurina/farmacologia , Proteínas Quinases JNK Ativadas por Mitógeno/antagonistas & inibidores , Purinas/química , Traumatismo por Reperfusão/enzimologia , Animais , Domínio Catalítico , Cães , Ativação Enzimática/efeitos dos fármacos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Haplorrinos , Concentração Inibidora 50 , Modelos Moleculares , Estrutura Molecular , Purinas/farmacologia , Ratos , Traumatismo por Reperfusão/tratamento farmacológico , Relação Estrutura-AtividadeRESUMO
Decreased p27(Kip1) levels are a poor prognostic factor in many malignancies, and can occur through up-regulation of SCF(Skp2) E3 ligase function, resulting in enhanced p27 ubiquitination and proteasome-mediated degradation. While proteasome inhibitors stabilize p27(Kip1), agents inhibiting SCF(Skp2) may represent more directly targeted drugs with the promise of enhanced efficacy and reduced toxicity. Using high-throughput screening, we identified Compound A (CpdA), which interfered with SCF(Skp2) ligase function in vitro, and induced specific accumulation of p21 and other SCF(Skp2) substrates in cells without activating a heat-shock protein response. CpdA prevented incorporation of Skp2 into the SCF(Skp2) ligase, and induced G(1)/S cell-cycle arrest as well as SCF(Skp2)- and p27-dependent cell killing. This programmed cell death was caspase-independent, and instead occurred through activation of autophagy. In models of multiple myeloma, CpdA overcame resistance to dexamethasone, doxorubicin, and melphalan, as well as to bortezomib, and also acted synergistically with this proteasome inhibitor. Importantly, CpdA was active against patient-derived plasma cells and both myeloid and lymphoblastoid leukemia blasts, and showed preferential activity against neoplastic cells while relatively sparing other marrow components. These findings provide a rational framework for further development of SCF(Skp2) inhibitors as a novel class of antitumor agents.
