Discovery of triazoloquinoxaline as novel STING agonists via structure-based virtual screening

Stimulator of interferon genes (STING) is an endoplasmic reticulum adaptor facilitating innate immune signaling. Activation of STING leads to expression of interferons (IFNs) and pro-inflammatory cytokines which is associated with antiviral and antitumor responses. It is imperative to discovery potent compounds that precisely modulate STING. Herein, we describe the discovery of triazoloquinoxaline 1a as a novel STING agonist via Structure-based Virtual Screening. Specifically, biochemical and cell-based assays suggested that 1a stimulated concentration-dependently mRNA expression of IFNβ, CXCL-10 and IL-6. Furthermore, 1a significantly induced phosphorylation of STING, TANK-binding kinases1 (TBK1) and interferon regulatory factor 3 (IRF3), suggesting the activation of STING and its downstream TBK1-IRF3 signaling axis. In addition, 1a activated secretion of secreted alkaline phosphatase (SEAP) in dose-dependent manner and EC₅₀ was 16.77 ± 3.814 μM, which is comparable with EC₅₀ of 2'3'-cGAMP (9.212 ± 2.229 μM). These studies revealed that 1a is a promising STING agonist possessing the potential to be further developed for antiviral and antitumor treatment.