DNA topoisomerase IIα (TOP2A)

DNA topoisomerase IIα is an essential enzyme encoded by the *TOP2A* gene that modulates the topological states of DNA during transcription, replication, and chromosome segregation. It acts by introducing transient double-stranded breaks into DNA, allowing the passage of one DNA helix through another, which resolves supercoils, knots, and tangles. This function is crucial for proper chromosome condensation and segregation during cell division. Topoisomerase IIα is the primary cellular target for several anticancer drugs known as topoisomerase II poisons, which exploit its enzymatic activity to induce lethal DNA damage in rapidly proliferating cells. The enzyme’s activity and drug sensitivity are regulated by post-translational modifications and protein interactions. Elevated TOP2A expression is a marker for sensitivity to specific chemotherapeutics, and both acquired resistance and toxicity remain significant clinical challenges.

Other names

Topo IIαTopoisomerase II alphaTOP2AType II topoisomerase αTopo II-A

Topoisomerase II poisons: stabilize the DNA–enzyme cleavage complex, leading to persistent DNA double-strand breaks and cell death (apoptosis). Catalytic inhibitors: inhibit enzyme without stabilizing cleavage complexes (may inhibit ATPase activity or DNA breakage functions).