MMAE amplified the STING signaling cascade by increasing the number of STING puncta induced by CDNs.

Abstract

(A) Chemical structure of VcMMAE (valine-citrulline (Vc) conjugate to MMAE, a part of ADC). (B) HeLa cells stably expressing hSTING-GFP were treated with 3’3’-cGAMP (2 μM), cyclic-di-AMP (10 μM), HT-DNA (2 μg, transfection with PEI) with or without MMAE (1 μM) for 2 h or 8 h (HT-DNA) in the presence or absence of brefeldin A (BFA 1μM), followed by confocal imaging. Green, STING-GFP. Nuclei were stained with 4’,6-diamidino-2-phenylindole (DAPI; blue). Scale bars, 10 μm. (C and D) THP1-Lucia ISG cells were stimulated with cGAMP (0.5 μM) for 24 h (C) or 6 h (D) in the presence or absence of MMAE (indicated doses or 1 μM) or VcMMAE (indicated doses or 1 μM). Fold changes in luminescent signals were normalized to cGAMP-treated cells (C). The induction of CXCL10, CCL5, IL-6, TNFα, IFITM1, and IFIT3 expression was analyzed by real-time PCR (D). Data are presented as mean ± SEM and analyzed by one-way ANOVA (*p p p p (TIF)</p