Adozelesin triggers DNA damage response pathways and arrests SV40 DNA replication through replication protein A inactivation

The cyclopropylpyrroloindole anti-cancer drug, adozelesin, binds to and alk ylates DNA. Treatment of human cells with low levels of adozelesin results in potent inhibition of both cellular and simian virus 40 (SV40) DNA replic ation. Extracts were prepared from adozelesin-treated cells and shown to be deficient in their ability to support SV40 DNA replication in vitro, This effect on in vitro DNA replication was dependent on both the concentration of adozelesin used and the time of treatment but was not due to the presenc e of adozelesin in the in vitro assay, Adozelesin treatment of cells was sh own to result in the following: induction of p53 protein levels, hyperphosp horylation of replication protein A (RPA), and disruption of the p53-RPA co mplex (but not disruption of the RPA-cdc2 complex), indicating that adozele sin treatment triggers cellular DNA damage response pathways. Interestingly , in vitro DNA replication could be rescued in extracts from adozelesin-tre ated cells by the addition of exogenous RPA, Therefore, whereas adozelesin and other anti-cancer therapeutics trigger common DNA damage response marke rs, adozelesin causes DNA replication arrest through a unique mechanism. Th e S phase checkpoint response triggered by adozelesin acts by inactivating RPA in some function essential for SV40 DNA replication.