ferric-ammonium-citrate and Precursor-Cell-Lymphoblastic-Leukemia-Lymphoma

Drug resistance is a fundamental clinical concern in pediatric acute lymphoblastic leukemia (pALL), and methotrexate (MTX) is an essential chemotherapy drug administered for the treatment. In the current study, the effect of iron in response to methotrexate and its underlying mechanisms were investigated in pALL cells. CCRF-CEM and Nalm6 cell lines were selected as T and B-ALL subtypes. Cells were pretreated with ferric ammonium citrate, exposed to the IC50 concentration of MTX and cell viability was assessed using MTT, colony formation, and flow cytometry assays. Iron-loaded cells were strongly resistant to MTX cytotoxicity. The inhibitory effect of N-acetyl cysteine to reverse the acquired MTX resistance was greater than that of the iron chelator, deferasirox, highlighting the importance of iron-mediated ROS in MTX resistance. Subsequently, the upregulation of BCL2, SOD2, NRF2, and MRP1 was confirmed using quantitative RT-PCR. Moreover, a positive correlation was demonstrated between the MRP1 expression levels and bone marrow iron storage in pALL patients. Further supporting our findings were the hematoxylin and eosin-stained histological sections showing that iron-treated nude mice xenografts demonstrated significantly more liver damage than those unexposed to iron. Overall, iron is introduced as a player with a novel role contributing to methotrexate resistance in pALL. Our findings suggest that the patients' bone marrow iron stores are necessary to be assessed during the chemotherapy, and transfusions should be carefully administrated.

Topics: Acetylcysteine; Bone Marrow; Cell Line, Tumor; Cell Survival; Child; Child, Preschool; Deferasirox; Drug Resistance, Neoplasm; Female; Ferric Compounds; Free Radical Scavengers; Humans; Infant; Inhibitory Concentration 50; Iron; Iron Chelating Agents; Male; Methotrexate; Multidrug Resistance-Associated Proteins; NF-E2-Related Factor 2; Precursor B-Cell Lymphoblastic Leukemia-Lymphoma; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Precursor T-Cell Lymphoblastic Leukemia-Lymphoma; Proto-Oncogene Proteins c-bcl-2; Quaternary Ammonium Compounds; Reactive Oxygen Species; RNA, Messenger; Superoxide Dismutase; Transcriptome; Up-Regulation

It is known that iron is essential for cell growth and viability and that iron deprivation results in an inhibition in the synthesis of deoxyribonucleotides. However, steps leading to eventual cell death during iron deprivation are not fully understood. In the present study, we report that cellular iron-deficiency produced by exposure of human leukemic CCRF-CEM cells to gallium or the iron chelator deferoxamine (DFX) resulted in the inhibition of cell growth, condensation of chromatin, and the formation of DNA fragments (DNA-ladder), findings that are characteristic of apoptotic cell death. These effects of gallium and DFX were detected after a 48-hour incubation with cells and could be prevented by ferric ammonium citrate (FAC). Iron-deprivation produced a small increase in the endogenous expression of bcl-2 protein. Our studies provide additional information regarding the mechanism of cytotoxicity of gallium and DFX, and suggest, for the first time, a role for iron in the suppression of apoptotic cell death.

Topics: Apoptosis; Chromatin; Deferoxamine; Ferric Compounds; Gallium; Humans; Insulin; Iron; Neoplastic Stem Cells; Precursor Cell Lymphoblastic Leukemia-Lymphoma; Quaternary Ammonium Compounds; Recombinant Proteins