PT  - JOURNAL ARTICLE
AU  - Sabrina X. Van Ravenstein
AU  - Kavi P. Mehta
AU  - Tamar Kavlashvili
AU  - Jo Ann Byl
AU  - Runxiang Zhao
AU  - Neil Osheroff
AU  - David Cortez
AU  - James M. Dewar
TI  - Topoisomerase II poisons inhibit vertebrate DNA replication through distinct mechanisms
AID  - 10.1101/2021.10.12.464107
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2021.10.12.464107
4099  - http://biorxiv.org/content/early/2022/04/29/2021.10.12.464107.short
4100  - http://biorxiv.org/content/early/2022/04/29/2021.10.12.464107.full
AB  - 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 induces 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 inhibit replication fork progression. In human cells, etoposide stalls replication forks in a Top2-dependent manner, while doxorubicin stalls forks independently of Top2. However, both drugs exhibit Top2-dependent cytotoxicity. Thus, despite shared genetic requirements for cytotoxicity etoposide and doxorubicin inhibit DNA replication through distinct mechanisms.Competing Interest StatementThe authors have declared no competing interest.