RESUMO
BRAF(V600E) is the most frequent oncogenic protein kinase mutation known. Furthermore, inhibitors targeting "active" protein kinases have demonstrated significant utility in the therapeutic repertoire against cancer. Therefore, we pursued the development of specific kinase inhibitors targeting B-Raf, and the V600E allele in particular. By using a structure-guided discovery approach, a potent and selective inhibitor of active B-Raf has been discovered. PLX4720, a 7-azaindole derivative that inhibits B-Raf(V600E) with an IC(50) of 13 nM, defines a class of kinase inhibitor with marked selectivity in both biochemical and cellular assays. PLX4720 preferentially inhibits the active B-Raf(V600E) kinase compared with a broad spectrum of other kinases, and potent cytotoxic effects are also exclusive to cells bearing the V600E allele. Consistent with the high degree of selectivity, ERK phosphorylation is potently inhibited by PLX4720 in B-Raf(V600E)-bearing tumor cell lines but not in cells lacking oncogenic B-Raf. In melanoma models, PLX4720 induces cell cycle arrest and apoptosis exclusively in B-Raf(V600E)-positive cells. In B-Raf(V600E)-dependent tumor xenograft models, orally dosed PLX4720 causes significant tumor growth delays, including tumor regressions, without evidence of toxicity. The work described here represents the entire discovery process, from initial identification through structural and biological studies in animal models to a promising therapeutic for testing in cancer patients bearing B-Raf(V600E)-driven tumors.
Assuntos
Apoptose/efeitos dos fármacos , Indóis/química , Melanoma/tratamento farmacológico , Modelos Moleculares , Oncogenes/genética , Inibidores de Proteínas Quinases/química , Proteínas Proto-Oncogênicas B-raf/antagonistas & inibidores , Sulfonamidas/química , Animais , Ciclo Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Escherichia coli , Humanos , Indóis/uso terapêutico , Concentração Inibidora 50 , Camundongos , Camundongos SCID , Estrutura Molecular , Fosforilação/efeitos dos fármacos , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Proto-Oncogênicas B-raf/genética , Sulfonamidas/uso terapêuticoRESUMO
The design and synthesis of a novel series of potent and cell permeable peptidomimetic inhibitors of the human beta-secretase (BACE) are described. These inhibitors feature a hydroxyethyl secondary amine isostere and a novel aromatic ring replacement for the C-terminus. The crystal structure of BACE in complex with this hydroxyethyl secondary amine isostere inhibitor is also presented.
Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/química , Modelos Moleculares , Peptídeos/química , Ácidos Ftálicos/síntese química , Precursor de Proteína beta-Amiloide/química , Linhagem Celular , Cristalografia por Raios X , Desenho de Fármacos , Humanos , Mimetismo Molecular , Estrutura Molecular , Ácidos Ftálicos/química , Ácidos Ftálicos/farmacologia , EstereoisomerismoRESUMO
The hydroxyethylene (HE) transition state isostere was developed as a scaffold to provide potent, small molecule inhibitors of human beta-secretase (BACE). The previous work on the statine series proved critical to the discovery of HE structure-activity relationships. Compound 20 with the N-terminal isophthalamide proved to be the most potent HE inhibitor (IC(50) = 30 nM) toward BACE. Unlike the statine series, we identified HE inhibitors without carboxylic acids on the C terminus, leading to enhanced cell penetration and making them attractive candidates for further drug development in Alzheimer's disease.
Assuntos
Amidas/síntese química , Ácido Aspártico Endopeptidases/química , Dipeptídeos/química , Etilenos/síntese química , Ácidos Ftálicos/síntese química , Inibidores de Proteases/síntese química , Amidas/química , Secretases da Proteína Precursora do Amiloide , Desenho de Fármacos , Endopeptidases , Etilenos/química , Humanos , Modelos Moleculares , Mimetismo Molecular , Ácidos Ftálicos/química , Inibidores de Proteases/química , Relação Estrutura-AtividadeRESUMO
We describe the development of statine-based peptidomimetic inhibitors of human beta-secretase (BACE). The conversion of the peptide inhibitor 1 into cell-permeable peptidomimetic inhibitors of BACE was achieved through an iterative strategy of conceptually subdividing 1 into three regions: an N-terminal portion, a central statine-containing core, and a C-terminus. Replacement of the amino acid residues of 1 with moieties with less peptidic character was done with retention of BACE enzyme inhibitory activity. This approach led to the identification of the cell-permeable BACE inhibitor 38 that demonstrated BACE-mechanism-selective inhibition of Abeta secretion in human embryonic kidney cells.
Assuntos
Aminoácidos/síntese química , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Inibidores Enzimáticos/síntese química , Oligopeptídeos/química , Aminoácidos/química , Aminoácidos/farmacologia , Secretases da Proteína Precursora do Amiloide , Peptídeos beta-Amiloides/antagonistas & inibidores , Peptídeos beta-Amiloides/biossíntese , Linhagem Celular , Endopeptidases , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Humanos , Mimetismo Molecular , Relação Estrutura-AtividadeRESUMO
By use of the effectively cleaved beta-secretase (BACE) substrate (1), incorporation of a statine in P(1) resulted in a weak inhibitor 13 of the enzyme. Further substitution of P(1)'-Asp by P(1)'-Val in 13 results in a potent inhibitor 22 of BACE. Removal of the P(10)-P(5) residues on the N-terminal part of inhibitor 22 resulted in no loss of potency (23). C-terminal truncations of inhibitor 22 generally led to significant loss of potency.
