DIBI, a novel 3-hydroxypyridin-4-one chelator iron-binding polymer, inhibits breast cancer cell growth and functions as a chemosensitizer by promoting S-phase DNA damage Anna L. Greenshields . Melanie R. Power Coombs . Wasundara Fernando . Bruce E. Holbein . David W. Hoskin Received: 31 July 2019 / Accepted: 10 October 2019 Ó Springer Nature B.V. 2019 Abstract Breast cancer is a leading cause of cancer- related death in women; however, chemotherapy of breast cancer is often hindered by dose-limiting toxicities, demonstrating the need for less toxic approaches to treatment. Since the rapid growth and metabolism of breast cancer cells results in an increased requirement for iron, withdrawal of bioavailable iron using highly selective iron chelators has been suggested to represent a new approach to breast cancer treatment. Here we show that the recently developed iron-binding polymer DIBI inhib- ited the growth of five different breast cancer cell lines (SK-BR3, MDA-MB-468, MDA-MB-231, MCF-7, and T47D). In cultures of MDA-MB-468 breast cancer cells, which were most sensitive to DIBI-mediated growth inhibition, iron withdrawal was associated with increased expression of transferrin receptor 1 and ferritin H mRNA but decreased expression of ferro- portin mRNA. MDA-MB-468 cells that were exposed to DIBI experienced double-strand DNA breaks during the S phase of the cell cycle. DNA damage was not mediated by reactive oxygen species (ROS) since DIBI-treated MDA-MB-468 cells exhibited a reduction in intracellular ROS. DIBI-treated MDA- MB-468 cells also showed increased sensitivity to growth inhibition by the chemotherapeutic drugs cisplatin, doxorubicin, and 4-hydroperoxy cyclophos- phamide (active metabolite of cyclophosphamide). Combination treatment of MDA-MB-468 cells with DIBI and cisplatin caused greater DNA damage than either treatment alone, which was also associated with an increase in apoptotic cell death. Taken together, these findings suggest that DIBI-mediated iron with- drawal may enhance the effect of chemotherapeutic agents used in breast cancer treatment. Keywords Breast cancer Á Chemotherapy Á DNA damage Á Iron chelation Introduction Worldwide, breast cancer is the most commonly diagnosed cancer in women with metastatic breast cancer being the leading cause of cancer-related death A. L. Greenshields Á M. R. Power Coombs Á W. Fernando Á D. W. Hoskin Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada B. E. Holbein Chelation Partners Inc., Guelph, ON, Canada D. W. Hoskin (&) Department of Microbiology and Immunology, Faculty of Medicine, Dalhousie University, 5850 College Street, P.O. Box 15000, Halifax, NS B3H 4R2, Canada e-mail: d.w.hoskin@dal.ca D. W. Hoskin Department of Surgery, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada 123 Biometals https://doi.org/10.1007/s10534-019-00222-3