The Hemin Treatment Impairs the Cell Survival of Hormone-Dependent and Hormone-Independent Human Breast Cancer Through the Regulation of “HO-1/Iron” Axis

Abstract

We have previously reported that the overexpression of Heme Oxygenase-1 (HO- 1), an enzyme that catalyzes heme degradation and releases iron, impairs breast cancer (BC) cell survival in human triple-negative (MDA-MB-231) BC cell lines, most likely through ferroptosis induction. In this study, we aimed to evaluate the effect of hemin, a drug commercially available thatmodulates the activity of HO- 1, in the modulation on hormone-dependent and independent BC cell survival and to assess the involvement of HO-1. To this end, we treated the T47D and MDA-MB-231 cell line with hemin (36h). We studied cell viability (crystal violet), iron storage (Prussian blue), ROS levels (DFCA), lipid peroxidation (MDA accumulation) and the expression of the iron importer ZIP14 (immunocytochemistry). We found that hemin treatment decreased T47D and MDA-MB231 cell viability (p<0.01 in both) and increased iron storage (p<0.05 in both), ROS levels (p<0.05 and p<0.001 respectively), MDA accumulation (p<0.01 in both) and ZIP14 expression. The treatment with iron chelator (deferoxamine) reversed the reduction of cell viability induced by hemin in both cell lines (p<0.001 in both). When HO-1 was inhibited with SNPP in MDA-MB231 cells, we detected an increase in the cell viability (p<0.01). Similarly, the overexpression of an enzymatically inactive HO-1 in T47D increased the cell viability (p<0.05). In conclusion, the hemin effect on the BC cells would be independent of the breast tumor subtype. In hormone-dependent and independent BC, the hemin impairs cell viability through the HO-1 induction that produces an increase in free iron accumulation, ROS production and lipid peroxidation, being the enzymatic activity of HO-1 necessary for the hemin effect on cell viability.