RESUMO
Tactical disruption of protein synthesis is an attractive therapeutic strategy, with the first-in-class eIF4A-targeting compound zotatifin in clinical evaluation for cancer and COVID-19. The full cellular impact and mechanisms of these potent molecules are undefined at a proteomic level. Here, we report mass spectrometry analysis of translational reprogramming by rocaglates, cap-dependent initiation disruptors that include zotatifin. We find effects to be far more complex than simple "translational inhibition" as currently defined. Translatome analysis by TMT-pSILAC (tandem mass tag-pulse stable isotope labeling with amino acids in cell culture mass spectrometry) reveals myriad upregulated proteins that drive hitherto unrecognized cytotoxic mechanisms, including GEF-H1-mediated anti-survival RHOA/JNK activation. Surprisingly, these responses are not replicated by eIF4A silencing, indicating a broader translational adaptation than currently understood. Translation machinery analysis by MATRIX (mass spectrometry analysis of active translation factors using ribosome density fractionation and isotopic labeling experiments) identifies rocaglate-specific dependence on specific translation factors including eEF1ε1 that drive translatome remodeling. Our proteome-level interrogation reveals that the complete cellular response to these historical "translation inhibitors" is mediated by comprehensive translational landscape remodeling.
Assuntos
Biossíntese de Proteínas/efeitos dos fármacos , Inibidores da Síntese de Proteínas/farmacologia , Animais , Benzofuranos/farmacologia , Linhagem Celular Tumoral , Fator de Iniciação 4A em Eucariotos/efeitos dos fármacos , Fator de Iniciação 4A em Eucariotos/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos NOD , Cultura Primária de Células , Biossíntese de Proteínas/fisiologia , Proteômica/métodos , Ribossomos/metabolismo , Transcriptoma/efeitos dos fármacos , Transcriptoma/genética , Triterpenos/farmacologiaRESUMO
Flavaglines are complex natural products that are found in several medicinal plants of Southeast Asia in the genus Aglaia; these compounds have shown exceptional anticancer and cytoprotective activities. This review describes the significance of flavaglines as a new class of pharmacological agents and presents recent developments in their synthesis, structure-activity relationships, identification of their molecular targets and modes of action. Flavaglines display a unique profile of anticancer activities that are mediated by two classes of unrelated proteins: prohibitins and the translation initiation factor eIF4A. The identification of these molecular targets is expected to accelerate advancement toward clinical studies. The selectivity of cytotoxicity towards cancer cells has been shown to be due to an inhibition of the transcription factor HSF1 and an upregulation of the tumor suppressor TXNIP. In addition, flavaglines display potent anti-inflammatory, cardioprotective and neuroprotective activities; however, the mechanisms underlying these activities are yet to be elucidated.
Assuntos
Antineoplásicos/farmacologia , Produtos Biológicos/farmacologia , Fator de Iniciação 4A em Eucariotos/efeitos dos fármacos , Proteínas Repressoras/antagonistas & inibidores , Antineoplásicos/química , Produtos Biológicos/química , Humanos , Proibitinas , Relação Estrutura-AtividadeRESUMO
A recent publication revealing that the cytotoxic marine natural product pateamine A targets eukaryotic initiation factor eIF4A continues a story with lessons for both chemists and biologists, that is, the significance of natural products, the importance of synthetic organic chemistry, the small molecule regulation of eukaryotic translation machinery, and possibly a new approach to cancer chemotherapy.
Assuntos
Compostos de Epóxi/uso terapêutico , Fator de Iniciação 4A em Eucariotos/antagonistas & inibidores , Macrolídeos/uso terapêutico , Tiazóis/uso terapêutico , Antineoplásicos/síntese química , Antineoplásicos/farmacologia , Compostos de Epóxi/síntese química , Compostos de Epóxi/química , Compostos de Epóxi/farmacologia , Fator de Iniciação 4A em Eucariotos/efeitos dos fármacos , Fator de Iniciação 4A em Eucariotos/genética , Macrolídeos/síntese química , Macrolídeos/química , Macrolídeos/farmacologia , Modelos Genéticos , Modelos Moleculares , Biossíntese de Proteínas/efeitos dos fármacos , RNA Mensageiro/genética , Tiazóis/síntese química , Tiazóis/química , Tiazóis/farmacologiaRESUMO
Translation initiation in eukaryotes is accomplished through the coordinated and orderly action of a large number of proteins, including the eIF4 initiation factors. Herein, we report that pateamine A (PatA), a potent antiproliferative and proapoptotic marine natural product, inhibits cap-dependent eukaryotic translation initiation. PatA bound to and enhanced the intrinsic enzymatic activities of eIF4A, yet it inhibited eIF4A-eIF4G association and promoted the formation of a stable ternary complex between eIF4A and eIF4B. These changes in eIF4A affinity for its partner proteins upon binding to PatA caused the stalling of initiation complexes on mRNA in vitro and induced stress granule formation in vivo. These results suggest that PatA will be a valuable molecular probe for future studies of eukaryotic translation initiation and may serve as a lead compound for the development of anticancer agents.