Kim et al. BMC Cancer 2012, 12:147 http://www.biomedcentral.com/1471-2407/12/147 R E S E A R C H A R T I C L E Open Access Tetrathiomolybdate sensitizes ovarian cancer cells to anticancer drugs doxorubicin, fenretinide, 5-fluorouracil and mitomycin C Kyu Kwang Kim1*, Thilo S Lange1,2, Rakesh K Singh1, Laurent Brard3 and Richard G Moore1 Abstract Background: Our recent study showed that tetrathiomolybdate (TM), a drug to treat copper overload disorders, can sensitize drug-resistant endometrial cancer cells to reactive oxygen species (ROS)-generating anticancer drug doxorubicin. To expand these findings in the present study we explore TM efficacy in combination with a spectrum of ROS-generating anticancer drugs including mitomycin C, fenretinide, 5-fluorouracil and doxorubicin in ovarian cancer cells as a model system. Methods: The effects of TM alone or in combination with doxorubicin, mitomycin C, fenretinide, or 5-fluorouracil were evaluated using a sulforhodamine B assay. Flow cytometry was used to detect the induction of apoptosis and ROS generation. Immunoblot analysis was carried out to investigate changes in signaling pathways. Results: TM potentiated doxorubicin-induced cytotoxicity and modulated key regulators of apoptosis (PARP, caspases, JNK and p38 MAPK) in SKOV-3 and A2780 ovarian cancer cell lines. These effects were linked to the increased production of ROS, as shown in SKOV-3 cells. ROS scavenging by ascorbic acid blocked the sensitization of cells by TM. TM also sensitized SKOV-3 to mitomycin C, fenretinide, and 5-fluorouracil. The increased cytotoxicity of these drugs in combination with TM was correlated with the activity of ROS, loss of a pro-survival factor (e.g. XIAP) and the appearance of a pro-apoptotic marker (e.g. PARP cleavage). Conclusions: Our data show that TM increases the efficacy of various anticancer drugs in ovarian cancer cells in a ROS-dependent manner. Keywords: Tetrathiomolybdate, Combination treatment, Doxorubicin, Mitomycin C, Fenretinide, 5-fluorouracil, ROS generation Background Ovarian cancer is the second most common gynecologi- cal malignancy and the leading cause of gynecologic can- cer deaths in the United States [1]. The initial treatment for women diagnosed with ovarian cancer includes cytor- eductive surgery followed by platinum based adjuvant chemotherapy [2-4]. Although most women will have an initial response to primary treatment, most will even- tually experience a recurrence with the development of * Correspondence: KKim@wihri.org 1Molecular Therapeutics Laboratory, Program in Women’s Oncology, Departments of Obstetrics and Gynecology, Women and Infants Hospital, Alpert Medical School, Brown University, 101 Dudley Street, Providence, RI 02905, USA Full list of author information is available at the end of the article chemoresistant disease. Improved chemotherapeutic agents and sensitizers for resistant tumors are needed. In the present report we assess the effect of ammonium tetrathiomolybdate (TM) on the efficacy of a panel of common anticancer drugs in combination treatment against ovarian cancer cell lines in vitro. Due to the tetra- hedral [MoS4]2- anion, TM can function as a chelator and was first therapeutically used to treat copper toxico- sis in Wilson’s disease [5]. TM is known to decrease angiogenesis and cancer cell growth through the inhibi- tion of cellular antioxidant copper zinc superoxide dis- mutase (SOD1) [6] and to elevate levels of cellular reactive oxygen species (ROS) [7,8]. Recent studies revealed that TM can also enhance the uptake and effi- cacy of cisplatin in human ovarian tumors [9]. Details to © 2012 Kim et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.