C-178

C-178 (CAS No.: 329198-87-0) is a synthetic small-molecule, research-grade chemical probe for biomedical research and drug discovery, classified as a selective covalent inhibitor of the stimulator of interferon genes STING pathway; STING is a conserved adaptor protein localized on the endoplasmic reticulum membrane and plays a central role in cytosolic DNA sensing and the induction of type I interferons in innate immunity in vertebrates. This compound is known to covalently target the regulatory cysteine residue Cys91 on STING, inhibiting the palmitoylation event required for signal transduction, thereby blocking the recruitment and phosphorylation of TANK-binding kinase TBK1, attenuating downstream IRF3 activation, and reducing interferon β (IFN-β)-related gene expression in cellular models; in in vitro studies, it shows selective inhibitory activity against STING-driven outputs relative to the RIG-I pathway or activation directly at the TBK1 level. Based on reporter gene and transcriptional assays, activity in the nanomolar to low micromolar range can be observed in human HEK293/HEK293T cells as well as mouse-derived bone marrow-derived macrophages, while exhibiting certain species-dependent characteristics, namely more robust inhibition of agonist-induced STING signaling in mouse systems and context-dependent inhibitory effects in human cells. As a tool compound for mechanism validation and target identification, C-178 is commonly used to dissect STING palmitoylation-dependent checkpoints, confirm intervention at the receptor-adaptor level of innate immune signaling pathways, and support screening cascades oriented toward regulation of nucleic acid sensing; typical applications include quantitative assessment of interferon reporter activity and Ifnb1 transcription in cell lines and primary macrophages under stimulation conditions such as cyclic dinucleotides, double-stranded DNA, or lipopolysaccharide. The concentration or dose used in experiments generally depends on the specific experimental design and research objectives; this product is for laboratory research only and is not intended for diagnostic procedures, clinical use, or any form of ingestion.