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SA-49, a novel aloperine derivative, induces MITF-dependent lysosomal degradation of PD-L1

BACKGROUND: Programmed death-ligand 1 (PD-L1) is a T-cell inhibitory checkpoint molecule that suppresses antitumor immunity. Anti-PD-L1 antibodies have shown remarkable promise in treating tumors, but the patient response rate is low. Therefore, small-molecule checkpoint inhibitors blocking PD-L1 fu...

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Detalles Bibliográficos
Autores principales: Zhang, Na, Dou, Yueying, Liu, Lu, Zhang, Xin, Liu, Xiaojia, Zeng, Qingxuan, Liu, Yang, Yin, Mingxiao, Liu, Xiujun, Deng, Hongbin, Song, Danqing
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Elsevier 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6414307/
https://www.ncbi.nlm.nih.gov/pubmed/30711516
http://dx.doi.org/10.1016/j.ebiom.2019.01.054
Descripción
Sumario:BACKGROUND: Programmed death-ligand 1 (PD-L1) is a T-cell inhibitory checkpoint molecule that suppresses antitumor immunity. Anti-PD-L1 antibodies have shown remarkable promise in treating tumors, but the patient response rate is low. Therefore, small-molecule checkpoint inhibitors blocking PD-L1 function are urgently needed. METHODS: Changes of protein expression and phosphorylation levels were determined by immunoblotting. The level of Membrane PD-L1 was examined by flow cytometer. Cytotoxicity of T cells and NK cells toward tumor cells were detected using LDH and cell index assays. Lysosome function was investigated by NAG assay. Changes in lysosomal-related genes were measured by RT-PCR. In vivo anti-NSCLC cancer effects were assessed using C57BL/6 mice bearing Lewis tumor xenografts. FINDINGS: We identified SA-49 as a new regulator of PD-L1 expression from a series of novel aloperine derivatives. SA-49 decreased the expression of PD-L1 in NSCLC cells and enhanced the cytotoxicity of co-cultured T and NK cells toward tumor cells. Importantly, lysosomal pathway contributed to SA-49-mediated down-regulation of PD-L1. SA-49 increased the biogenesis of lysosome and promoted translocation of PD-L1 to lysosome for proteolysis, which was associated with nuclear translocation of MITF. SA-49-induced MITF translocation acted through activation of PKCα and subsequently suppression of GSK3β activity. Furthermore, SA-49 suppressed Lewis tumor xenograft growth by activating immune microenvironment in C57BL/6 mice. INTERPRETATION: Our data demonstrate that SA-49 can be used to regulate PD-L1 in cancer cells and trigger its degradation by activating lysosome function.