RESUMO
Phenotypic screening in drug discovery has been revived with the expectation of providing promising lead compounds and drug targets and improving the success rate of drug approval. However, target identification remains a major bottleneck in phenotype-based drug discovery. We identified the lead compounds K542 and K405 with a selective inhibition of cell viability against sphingosine-1-phosphate lyase 1 (SGPL1)-transduced ES-2 cells by phenotypic screening. We therefore performed an in vivo pharmacological examination and observed the antitumor activity of K542 in an HT-1080 tumor-bearing mouse xenograft model. SGPL1 was expected to be a therapeutic target in some cancers, suggesting that these lead molecules might be promising candidates; however, their mechanisms of action still remain unexplained. We therefore synthesized the affinity probe Ind-tag derived from K542 and identified the proteins binding to Ind-tag via a pull-down experiment. Proteomics and biochemical analyses revealed that the target molecule of these lead compounds was Nicotinamide phosphoribosyltransferase (NAMPT). We established K542-resistant DLD-1 and HT-1080 cells, and genetic analyses of these cells identified a missense mutation in the NAMPT-encoding gene. This enzymatic experiment clearly showed that K393 exerts enzymatic inhibition against NAMPT. These proteomics, genetics and biochemical analyses clarified that compounds K542 and K405 were NAMPT inhibitors.
Assuntos
Ensaios de Seleção de Medicamentos Antitumorais/métodos , Nicotinamida Fosforribosiltransferase/efeitos dos fármacos , Nicotinamida Fosforribosiltransferase/metabolismo , Aldeído Liases/efeitos dos fármacos , Aldeído Liases/metabolismo , Animais , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Citocinas/efeitos dos fármacos , Citocinas/metabolismo , Descoberta de Drogas/métodos , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/farmacologia , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Modelos Moleculares , Neoplasias/tratamento farmacológico , Fenótipo , Relação Estrutura-AtividadeRESUMO
A spermine-conjugated ethyl phosphotriester oligonucleotide was obtained by solid-phase synthesis based on phosphoramidite chemistry. The ethyl phosphotriester linkage was robust to exonuclease digestion and stable in fetal bovine serum. Cell membrane permeability of the spermine-conjugated ethyl phosphotriester oligonucleotide was studied by fluorescence experiments. The effective cell penetrating potency of the spermine-conjugated ethyl phosphotriester oligonucleotide was determined by confocal laser scanning microscopy and measurement of intracellular fluorescence intensity.