Topoisomerase II poisons inhibit vertebrate DNA replication through distinct mechanisms. (16th May 2022)

• Record Type: Journal Article
• Authors: Van Ravenstein, Sabrina X; Mehta, Kavi P; Kavlashvili, Tamar; Byl, Jo Ann W; Zhao, Runxiang; Osheroff, Neil; Cortez, David; Dewar, James M
• Is Part Of: EMBO journal. Volume 41:Number 12(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-05-16
• Subjects: cancer -- chemotherapy -- DNA Damage -- DNA replication -- topoisomerase; Molecular biology -- Periodicals; 572.805
• DOI: 10.15252/embj.2022110632
• Languages: English
• ISSNs: 0261-4189

Abstract

Abstract: Topoisomerase II (TOP2) unlinks chromosomes during vertebrate DNA replication. TOP2 "poisons" are widely used chemotherapeutics that stabilize TOP2 complexes on DNA, leading to cytotoxic DNA breaks. However, it is unclear how these drugs affect DNA replication, which is a major target of TOP2 poisons. Using Xenopus egg extracts, we show that the TOP2 poisons etoposide and doxorubicin both inhibit DNA replication through different mechanisms. Etoposide induces TOP2‐dependent DNA breaks and TOP2‐dependent fork stalling by trapping TOP2 behind replication forks. In contrast, doxorubicin does not lead to appreciable break formation and instead intercalates into parental DNA to stall replication forks independently of TOP2. In human cells, etoposide stalls forks in a TOP2‐dependent manner, while doxorubicin stalls forks independently of TOP2. However, both drugs exhibit TOP2‐dependent cytotoxicity. Thus, etoposide and doxorubicin inhibit DNA replication through distinct mechanisms despite shared genetic requirements for cytotoxicity. Synopsis: Etoposide and doxorubicin are chemotherapeutics that induce cytotoxic DNA breaks by targeting topoisomerase II, which is important for DNA replication. Here, etoposide and doxorubicin are shown to both inhibit DNA replication but, surprisingly, through distinct mechanisms. The topoisomerase II poisons etoposide and doxorubicin both inhibit DNA replication. During DNA replication, etoposide behaves as a canonical topoisomerase II poison, while doxorubicin does not. Etoposide traps topoisomerase II behind replication forks to induce topological stress. Doxorubicin intercalates into unreplicated DNA and inhibits DNA unwinding. In human cells, replication inhibition by etoposide is topoisomerase II‐dependent, while replication inhibition by doxorubicin is topoisomerase II‐independent. Abstract : While the chemotherapeutic etoposide behaves as a canonical TOP2 poison causing topological stress, doxorubicin intercalates into unreplicated DNA and blocks its unwinding.