Fig. 3

Niclosamide disrupts PD-L1 glycosylation and triggers ER stress. a The schematic of PD-L1 protein structure and glycosylation sites. SIG: signal peptide; IgV: immunoglobulin variable; IgC: immunoglobulin constant; TM: transmembrane; ICD: intracellular domain. b Representative Western blot of HuR and PD-L1 protein levels in sgControl and HuR-knockout MDA-MB-231 and HeLa cells. c PD-L1 and N-linked glycosylation associated protein levels upon niclosamide treatment in MDA-MB-231 cells. d Representative Western blot of multiple ER stress-related proteins in MDA-MB-231 cells with different concentrations of niclosamide treatment for 48 h. e Representative Western blot of multiple ER stress-related proteins in MDA-MB-231 cells with 1.0 µM niclosamide treatment for different time intervals. f GFP-expressing MDA-MB-231cells co-cultured with activated T cells for 48 h with or without niclosamide (1.0, 2.0 μM). The tumor cell to T cell ratio, 1:1 (n = 3). GFP- expressing MDA-MB-231 cells [38] co-cultured with activated T cell with or without niclosamide (g) and anti-PD-1 antibody (h). The tumor cell to T cell ratio, 1:1 (n = 3). The quantitative analysis of T cell-mediated killing is presented as mean ± SEM. Two-way ANOVA (f–h). ns, no significance, *p < 0.05, **p < 0.01, ***p < 0.001, ****p < 0.0001