Oxynitidine Derivatives Useful as Inhibitors of Topoisomerase IB (TOP1) and Tyrosyl-DNA Phosphodiesterase 1 (TDP1) for Treating Cancer
Topoisomerase 1B (TOP1) is an enzyme that relieves the torsional strain in DNA. To relieve the torsional strain, TOP1B cleaves one strand of DNA and forms a transient complex called a TOP1-DNA covalent cleavage complex (TOP1cc). TOP1 inhibitors – such as camptothecin – stabilize the TOP1cc and prevent relegation of the broken DNA which, when encountered by replication and transcription machinery, triggers cell death. The DNA damage generated by the TOP1cc can be repaired by several pathways, including tyrosyl-DNA phosphodiesterase 1 (TDP1) pathway.