The iron effect on the cell survival of breast cancer depends on its overload level

Abstract

Cancer cells develop metabolic alterations to sustain an increased proliferation. The iron is an essential element required for many bi- ological processes and its metabolism is disrupted in breast cancer (BC) cells. It has been reported that high cellular iron concentra- tion accelerates the proliferation of BC cells. However, recent works described that the iron overload induce cell death by ferroptosis, a form of cell death caused by iron-catalyzed excessive peroxidation of polyunsaturated fatty acids; being a promising therapeutic target for therapy-resistant cancers. In this study we aimed to analyze the behavior of BC cells exposed to an increasing iron overload. To that end, the murine BC cell line, LM3, was treated with increasing ferric ammonium citrate (FAC) concentrations (0- 400 μM) for 48 h and cell viability (by crystal violet), intracellular iron (by Prussian Blue), reac- tive oxygen species (ROS) (by DFCA), lipid peroxidation (TBARS) (by MDA accumulation) and the expression of divalent metal trans- porter 1 (DMT1) by immunocytochemistry, were analyzed. LM3 cell viability increased after FAC treatment with 25 μM and 50 μM (p< 0.05) but decreased with 200 μM and 400 μM FAC (p< 0.05 and p< 0.01, respectively), respect to vehicle. The ROS levels increased after FAC treatment with 50 μM (p< 0.05), 200 μM (p< 0.001) and 400 μM (p< 0.001) compared to vehicle. In addition, we detected an increase in lipid peroxidation in LM3 cells treated with 200 μM and 400 μM of FAC compared to vehicle (p< 0.01, in both). Also, we found iron accumulation as hemosiderin form and high DMT1 importer expression in LM3 cells treated with 200 μM and 400 μM of FAC, compared to vehicle. Altogether these results suggest that the effect of iron on cell viability depends on its overload level and that a high iron overload promotes the iron entry through DMT1 and its accumulation as hemosiderin inducing lower cell viability through lipid peroxidation-dependent mechanisms.