RESUMEN
Tumor necrosis factor receptor-associated factor 2 (TRAF2) is a critical mediator of tumor necrosis factor-α (TNF-α) signaling. However, the regulatory mechanisms of TRAF2 are not fully understood. Here we show evidence that TRAF2 requires brefeldin A-inhibited guanine nucleotide-exchange factor 1 (BIG1) to be recruited into TNF receptor 1 (TNFR1) signaling complexes. In BIG1 knockdown cells, TNF-α-induced c-Jun N-terminal kinase (JNK) activation was attenuated and the sensitivity to TNF-α-induced apoptosis was increased. Since these trends correlated well with those of TRAF2 deficient cells as previously demonstrated, we tested whether BIG1 functions as an upstream regulator of TRAF2 in TNFR1 signaling. As expected, we found that knockdown of BIG1 suppressed TNF-α-dependent ubiquitination of TRAF2 that is required for JNK activation, and impaired the recruitment of TRAF2 to the TNFR1 signaling complex (complex I). Moreover, we found that the recruitment of TRAF2 to the death-inducing signaling complex termed complex II was also impaired in BIG1 knockdown cells. These results suggest that BIG1 is a key component of the machinery that drives TRAF2 to the signaling complexes formed after TNFR1 activation. Thus, our data demonstrate a novel and unexpected function of BIG1 that regulates TNFR1 signaling by targeting TRAF2.
Asunto(s)
Factores de Intercambio de Guanina Nucleótido/genética , Receptores Tipo I de Factores de Necrosis Tumoral/genética , Transducción de Señal/genética , Factor 2 Asociado a Receptor de TNF/genética , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Regulación de la Expresión Génica , Genes Reporteros , Factores de Intercambio de Guanina Nucleótido/antagonistas & inhibidores , Factores de Intercambio de Guanina Nucleótido/metabolismo , Células HeLa , Humanos , Proteínas Quinasas JNK Activadas por Mitógenos/antagonistas & inhibidores , Proteínas Quinasas JNK Activadas por Mitógenos/genética , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Luciferasas/genética , Luciferasas/metabolismo , FN-kappa B/antagonistas & inhibidores , FN-kappa B/genética , FN-kappa B/metabolismo , Unión Proteica , Transporte de Proteínas , Proteolisis/efectos de los fármacos , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Receptores Tipo I de Factores de Necrosis Tumoral/antagonistas & inhibidores , Receptores Tipo I de Factores de Necrosis Tumoral/metabolismo , Factor 2 Asociado a Receptor de TNF/antagonistas & inhibidores , Factor 2 Asociado a Receptor de TNF/metabolismo , Factor de Necrosis Tumoral alfa/farmacología , Ubiquitinación/efectos de los fármacosRESUMEN
Chimeric antigen receptor (CAR) T cells are effective against hematological cancers, but are less effective against solid tumors such as non-small cell lung cancer (NSCLC). One of the reasons is that only a few cell surface targets specific for NSCLC cells have been identified. Here, we report that CD98 heavy chain (hc) protein is overexpressed on the surface of NSCLC cells and is a potential target for CAR T cells against NSCLC. Screening of over 10,000 mAb clones raised against NSCLC cell lines showed that mAb H2A011 bound to NSCLC cells but not normal lung epithelial cells. H2A011 recognized CD98hc. Although CAR T cells derived from H2A011 could not be established presumably due to the high level of H2A011 reactivity in activated T cells, those derived from the anti-CD98hc mAb R8H283, which had been shown to lack reactivity with CD98hc glycoforms expressed on normal hematopoietic cells and some normal tissues, were successfully developed. R8H283 specifically reacted with NSCLC cells in six of 15 patients. R8H283-derived CAR T cells exerted significant anti-tumor effects in a xenograft NSCLC model in vivo. These results suggest that R8H283 CAR T cells may become a new therapeutic tool for NSCLC, although careful testing for off-tumor reactivity should be performed in the future.