DNA topoisomerase II (Type IIA topoisomerase) (Top2 or Topo II)

DNA topoisomerase II is a ubiquitous ATP-dependent enzyme that regulates DNA topology by introducing transient double-strand breaks and passing another segment of DNA through the break before resealing it[5][7]. This process resolves supercoils, knots, and tangles that arise during replication, transcription, and chromosome packaging. Mammalian cells have two isoforms: Top2α, crucial for cell division and chromosome segregation, and Top2β, important for transcriptional regulation and development[1][5]. Topoisomerase II is a major pharmacological target, especially for antineoplastic drugs used in cancer therapy, with its expression serving as a biomarker for proliferative activity[5]. Inhibiting Top2 leads to DNA damage, genomic instability, cell cycle arrest, and apoptosis, but is associated with notable safety concerns due to cytotoxic and genotoxic side effects[8].

Other names

Top2Topo IIDNA topoisomerase IIα (Top2α)DNA topoisomerase IIβ (Top2β)Type IIA topoisomerase

Stabilization of the topoisomerase II-DNA cleavage complex, leading to permanent double-strand DNA breaks. Inhibition of DNA religation, promoting DNA damage and apoptosis in rapidly dividing cells. Some drugs interfere with ATPase activity or other regulatory modifications (e.g. phosphorylation).