Open Access Open Badges Research article

Copper chelation selectively kills colon cancer cells through redox cycling and generation of reactive oxygen species

Maamoun Fatfat1, Raghida Abou Merhi2, Omar Rahal1, Detcho A Stoyanovsky3, Angela Zaki1, Hazar Haidar1, Valerian E Kagan3, Hala Gali-Muhtasib1* and Khaled Machaca4*

Author Affiliations

1 Department of Biology, American University of Beirut, Beirut, Lebanon

2 Department of Biology, Lebanese University, Beirut, Lebanon

3 Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, USA

4 Department of Physiology and Biophysics, Weill Cornell Medical College, Doha, Qatar

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BMC Cancer 2014, 14:527  doi:10.1186/1471-2407-14-527

Published: 21 July 2014



Metals including iron, copper and zinc are essential for physiological processes yet can be toxic at high concentrations. However the role of these metals in the progression of cancer is not well defined. Here we study the anti-tumor activity of the metal chelator, TPEN, and define its mechanism of action.


Multiple approaches were employed, including cell viability, cell cycle analysis, multiple measurements of apoptosis, and mitochondrial function. In addition we measured cellular metal contents and employed EPR to record redox cycling of TPEN–metal complexes. Mouse xenografts were also performed to test the efficacy of TPEN in vivo.


We show that metal chelation using TPEN (5μM) selectively induces cell death in HCT116 colon cancer cells without affecting the viability of non-cancerous colon or intestinal cells. Cell death was associated with increased levels of reactive oxygen species (ROS) and was inhibited by antioxidants and by prior chelation of copper. Interestingly, HCT116 cells accumulate copper to 7-folds higher levels than normal colon cells, and the TPEN-copper complex engages in redox cycling to generate hydroxyl radicals. Consistently, TPEN exhibits robust anti-tumor activity in vivo in colon cancer mouse xenografts.


Our data show that TPEN induces cell death by chelating copper to produce TPEN-copper complexes that engage in redox cycling to selectively eliminate colon cancer cells.

Colon cancer; Metal chelation; TPEN; Redox cycling; Copper; Reactive oxygen species