Chronic states of iron deficiency and excess in combination with erastin: An in-vitro study of acute monocytic leukemia (THP-1 cells)
Date
2025
Authors
Fenniri, Zachariah A. H.
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Abstract
Iron is essential for numerous biological processes, due to its inherent capacity to transfer electrons. This chemical feature is a double-edged sword, as excess iron catalyzes the formation of reactive oxygen species (ROS) that have potential to cause cellular damage and induce ferroptosis – an iron-dependent form of cell death. Dysregulated iron homeostasis, in favour of accumulation, is a central feature of highly proliferative leukemias, as it enables the required energy metabolism and biosynthesis for unrestrained proliferation. Iron deprivation through the use of iron chelators and the induction of ferroptosis are two potential avenues of clinical antileukemic treatment. The present study aimed to examine the effects of chronic states of iron deficiency and excess in THP-1 cells, an in-vitro model of acute monocytic leukemia (AMoL). Moreover, this study sought to examine the effects of these chronic iron states on THP-1 cell resistance to erastin, a compound that induces ferroptosis in many cells, but is largely ineffective in leukemic cell lines. THP-1 cells were cultured in various concentrations of ferric citrate or deferoxamine (DFO), a clinical iron chelator, for 96 hours to simulate chronic states of iron excess and deficiency, respectively. Following 72 hours of treatment, cells were administered erastin for the final 24 hours of treatment. Cell death, metabolic activity, and intracellular glutathione (GSH), a pivotal antioxidant, were quantified. Moderate to high doses of DFO induced marked cell death, as well as a notable reduction in metabolic activity and intracellular GSH. THP-1 cell resistance to erastin was partially attenuated by ferric citrate treatment, evidenced by a small but consistent iron-dose dependent increase in cell death. Similarly, intracellular GSH showed a subtle, insignificant iron-dose dependent reduction in erastin-treated cells. Metabolic activity in the surviving cells was unaffected. DFO is shown to act synergistically with erastin in THP-1 cells, inducing a significant increase in cell death,
and in the surviving cells, a reduction in metabolic activity. Likewise, intracellular GSH increases in the surviving cells of this cotreatment. Taken together, the present study demonstrates the robustness of THP-1 cells in states of iron excess and their sensitivity to iron deficiency. It also provides novel evidence of a synergy between DFO and erastin, and of ferric citrate attenuating THP-1 cell resistance to erastin.
Supervisors:
Patrick B. Walter and Jürgen Ehlting