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. 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].