RESEARCH ARTICLE Chronic Inhibition of STAT3/STAT5 in Treatment-Resistant Human Breast Cancer Cell Subtypes: Convergence on the ROS/ SUMO Pathway and Its Effects on xCT Expression and System xc- Activity Katja Linher-Melville1, Mina G. Nashed1, Robert G. Ungard1, Sina Haftchenary2, David A. Rosa2, Patrick T. Gunning2, Gurmit Singh1* a11111 1 Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, L8S 4L8, Canada, 2 Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, Ontario, L5L 1C6, Canada *
[email protected] OPEN ACCESS Abstract Citation: Linher-Melville K, Nashed MG, Ungard RG, Haftchenary S, Rosa DA, Gunning PT, et al. (2016) Pharmacologically targeting activated STAT3 and/or STAT5 has been an active area of - Chronic Inhibition of STAT3/STAT5 in Treatment- cancer research. The cystine/glutamate antiporter, system xc , contributes to redox balance Resistant Human Breast Cancer Cell Subtypes: and export of intracellularly produced glutamate in response to up-regulated glutaminolysis Convergence on the ROS/SUMO Pathway and Its in cancer cells. We have previously shown that blocking STAT3/5 using the small molecule Effects on xCT Expression and System xc- Activity. PLoS ONE 11(8): e0161202. doi:10.1371/journal. inhibitor, SH-4-54, which targets the SH2 domains of both proteins, increases xCT expres- - pone.0161202 sion, thereby increasing system xc activity in human breast cancer cells. The current inves- Editor: Ming Tan, University of South Alabama, tigation demonstrates that chronic SH-4-54 administration, followed by clonal selection of UNITED STATES treatment-resistant MDA-MB-231 and T47D breast cancer cells, elicits distinct subtype- Received: June 1, 2016 dependent effects.