RESUMEN
EGFR is an important therapeutic target for non-small cell lung cancers (NSCLCs). Tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib, are effective in cases with EGFR-activating mutations. However, most such cases become resistant through a secondary EGFR mutation, T790M. While the second-generation TKI afatinib has a higher affinity for double-mutant EGFRs, better efficacy is needed. Combining afatinib with the anti-EGFR monoclonal antibody cetuximab improves clinical outcomes, but the mechanism is unclear. Here we examined this effect using erythroleukemic K562 cells. The activating EGFR mutation L858R is sensitive to first-generation TKIs, and adding T790M confers resistance to these drugs. This double-mutant EGFR was moderately sensitive to afatinib, but responded weakly to cetuximab. Combined afatinib and cetuximab synergistically increased their cytotoxicity for K562 cells expressing the double-mutant EGFR. Apoptosis in these cells followed induction of the pro-apoptotic protein BIM. Unexpectedly, afatinib caused redistribution of EGFR to the cell surface through Rab11a-dependent recycling. Cetuximab reduced cell-surface EGFR, and total EGFR decreased synergistically when cetuximab was combined with afatinib. Our results suggest that the synergistic effect exerted by afatinib and cetuximab on NSCLCs is associated with BIM induction and alterations in EGFR status.
Asunto(s)
Anticuerpos Monoclonales Humanizados/farmacología , Antineoplásicos/farmacología , Receptores ErbB/metabolismo , Quinazolinas/farmacología , Proteínas de Unión al GTP rab/metabolismo , Afatinib , Animales , Anticuerpos Monoclonales/química , Apoptosis , Proteínas Reguladoras de la Apoptosis/metabolismo , Proteína 11 Similar a Bcl2 , Células COS , Membrana Celular/metabolismo , Cetuximab , Chlorocebus aethiops , Relación Dosis-Respuesta a Droga , Resistencia a Antineoplásicos , Receptores ErbB/genética , Células HeLa , Humanos , Células K562 , Proteínas de la Membrana/metabolismo , Microscopía Confocal , Microscopía Fluorescente , Mutación , Proteínas Proto-Oncogénicas/metabolismoRESUMEN
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
RESUMEN
Space flight produces an extreme environment with unique stressors, but little is known about how our body responds to these stresses. While there are many intractable limitations for in-flight space research, some can be overcome by utilizing gene knockout-disease model mice. Here, we report how deletion of Nrf2, a master regulator of stress defense pathways, affects the health of mice transported for a stay in the International Space Station (ISS). After 31 days in the ISS, all flight mice returned safely to Earth. Transcriptome and metabolome analyses revealed that the stresses of space travel evoked ageing-like changes of plasma metabolites and activated the Nrf2 signaling pathway. Especially, Nrf2 was found to be important for maintaining homeostasis of white adipose tissues. This study opens approaches for future space research utilizing murine gene knockout-disease models, and provides insights into mitigating space-induced stresses that limit the further exploration of space by humans.