Deferasirox-Dependent Iron Chelation Enhances Mitochondrial Dysfunction and Restores p53 Signaling by Stabilization of p53 Family Members in Leukemic Cells

Abstract

Iron is crucial to satisfy several mitochondrial functions including energy metabolism and oxidative phosphorylation. Patients affected by Myelodysplastic Syndromes (MDS) and acute myeloid leukemia (AML) are frequently characterized by iron overload (IOL), due to continuous red blood cell (RBC) transfusions. This event impacts the overall survival (OS) and it is associated with increased mortality in lower-risk MDS patients. Accordingly, the oral iron chelator Deferasirox (DFX) has been reported to improve the OS and delay leukemic transformation. However, the molecular players and the biological mechanisms laying behind remain currently mostly undefined. The aim of this study has been to investigate the potential anti-leukemic effect of DFX, by functionally and molecularly analyzing its effects in three different leukemia cell lines, harboring or not p53 mutations, and in human primary cells derived from 15 MDS/AML patients. Our findings indicated that DFX can lead to apoptosis, impairment of cell growth only in a context of IOL, and can induce a significant alteration of mitochondria network, with a sharp reduction in mitochondrial activity. Moreover, through a remarkable reduction of Murine Double Minute 2 (MDM2), known to regulate the stability of p53 and p73 proteins, we observed an enhancement of p53 transcriptional activity after DFX. Interestingly, this iron depletion-triggered signaling is enabled by p73, in the absence of p53, or in the presence of a p53 mutant form. In conclusion, we propose a mechanism by which the increased p53 family transcriptional activity and protein stability could explain the potential benefits of iron chelation therapy in terms of improving OS and delaying leukemic transformation.

Eltrombopag and its iron chelating properties in pediatric acute myeloid leukemia

“…In particular, since tumor cells show higher iron consumption than healthy cells [30], iron chelating agents represent a promising anticancer strategy. Several authors demonstrated that iron chelators inhibit proliferation and induces apoptosis in both hematological and solid tumors [21,31]. For example, the iron chelators deferiprone (DFP) and deferasirox (DFX) are two iron chelators approved for use in leukemic patients, being able to inhibit cancer cell proliferation [20][21][22].…”

“…Several authors demonstrated that iron chelators inhibit proliferation and induces apoptosis in both hematological and solid tumors [21,31]. For example, the iron chelators deferiprone (DFP) and deferasirox (DFX) are two iron chelators approved for use in leukemic patients, being able to inhibit cancer cell proliferation [20][21][22]. Among the innovative molecules under investigations for their emerging iron chelating properties, eltrombopag (ELT), the thrombopoietin receptor agonist used in immunethrombocytopenia (ITP) and aplastic anemia, shows anticancer properties related to its iron chelating properties [23], even though the possibility of using it is not yet concrete [24,25,32].…”

“…European Medicines Agency (EMA) approved three iron chelators for treatment of iron overload conditions: deferoxamine (DFO) generally used in thalassemia major, deferiprone (DFP) and deferasirox (DFX) instead indicated in leukemic patients. In particular, DFX has also anticancer properties since it limits cancer cell proliferation by inhibiting NF-kB [ 20 ] and enhances p53 transcriptional activity impairing leukemic cells growth [ 21 , 22 ]. Besides these compounds, other molecules with iron chelating properties are under investigations and among them one of the most promising is Eltrombopag (ELT), a thrombopoietin receptor agonist, normally indicated for use in immunethombocytopenia (ITP) and aplastic anemia.…”

The p53 Family: A Role in Lipid and Iron Metabolism

“…Like p53, p63, and p73 can be destabilized by an excess of heme ( Shen et al, 2014 ). Conversely, iron depletion was found to stabilize p73, and possibly p63, to promote apoptosis and cell cycle arrest in a p53-independent manner ( Calabrese et al, 2020 ). These data suggest that iron overload inhibits, whereas iron depletion promotes, p63 and p73 activity, which is similar to the effect of iron overload and depletion on p53.…”

Presenilin-Deficient Neurons and Astrocytes Display Normal Mitochondrial Phenotypes

“…Morphological analysis of mitochondria was performed in silico using a plug-in of ImageJ, the toolset MiNA (Mitochondrial Network Analysis) (Valente et al, 2017). MiNA allows semiautomated analysis and consists in images' preprocessing, to ensure quality, conversion to binary image, and in the production of the final skeleton for the quantitative analysis, as previously described (Calabrese et al, 2020). Briefly, images were opened on ImageJ and processed as follows: 1-Process/Filters/UnsharpMask; 2-Process/EnhanceLocal Contrast (CLAHE); 3-Process/Filters/Median; 4-Process/Binary/MakeBinary; 5-Process/Binary/Skeletonize; 6-Analyze/Skeleton/AnalyzeSkeleton(2D/3D); 7-Plugins/StuartLab/MiNAScripts/MiNAAnalyzeMorphology.…”