Chromomycin A3 is an inhibitor that selectively binds to GC-rich DNA sequences. Chromomycin A3 targets the DNA minor groove after forming a dimer with Mg2+. Chromomycin A3 inhibits DNA replication and transcription, blocks the binding of Sp1 transcription factor to target gene promoters, downregulates the expression of anti-apoptotic proteins such as FLIP, Mcl-1, and XIAP, and induces S-phase cycle arrest and caspase-dependent apoptosis in tumor cells. Chromomycin A3 can antagonize oxidative stress induced by glutathione depletion and neuronal apoptosis induced by Camptothecin (HY-15660). Chromomycin A3 can be used in basic research on malignant tumors such as cholangiocarcinoma, and is a potential chemosensitizer and GC-rich region probe[1][2][3].