A novel topoisomerase I inhibitor DIA-001 induces DNA damage mediated cell cycle arrest and apoptosis in cancer cell.

Background: DNA topoisomerase enzyme plays an essential role in controlling the DNA topology structure by binding to DNA and cutting the phosphate backbone of either one or both of the DNA strands. Here, we have identified a small molecule inhibitor, DIA-001, that directly binds to Topoisomerase 1 (Topo I) and promotes the Topo I-DNA adducts. Methods: In this study, we investigated the antitumor effects of DIA-001 using MTS assay and colony formation. We examined cell cycle of tumor cells with DIA-001 treatment in vitro by flow cytometry. And we investigated DNA damage and cell cycle marker protein after treatment with DIA-001 at different concentration and time point by western blot. Immunofluorescence was performance to detect the nuclear foci. The effects of DIA-001 on Top I and Topo II activities were examined by DNA relaxation assays. Results: We demonstrate that DIA-001 inhibit DNA replication and arrest cell cycle progression at the G2/M phase by directly binds to Topo I and promotes the Topo I-DNA adducts. In addition, DIA-001 can activate the DNA damage response signaling cascade, resulting in apoptosis in treated cells. Conclusions: Our findings show a novel compound for treatment of cancer cells with the potential as a chemotherapy candidate that is less toxic to normal cells.