Iron overload mediates cytarabine resistance in AML by inhibiting the TP53 signaling pathway

Abstract

Currently, chemotherapy remains the primary treatment for acute myeloid leukemia (AML). Drug resistance in AML cells is a critical factor contributing to the failure of chemotherapy remission and subsequent relapse. Iron overload frequently occurs in AML patients because of hematopoietic suppression or supportive blood transfusion therapy. Previous studies have indicated that iron overload may promote the progression of AML; however, the underlying mechanisms remain unclear. Our results demonstrate that, compared with TP53-wild-type AML cells, TP53-mutant AML cells exhibit increased resistance to cytarabine-induced cytotoxicity. Moreover, reducing TP53 expression in wild-type AML cells diminishes their sensitivity to cytarabine. The TP53 signaling pathway is essential for mediating cytarabine-induced apoptosis in AML cells. In this study, an iron overload model in AML cells via the use of ferric citrate is constructed. Our data indicate that iron overload can suppress the TP53/BCL2/BAX signaling pathway, counteracting cytarabine-induced apoptosis. In TP53 wild-type AML cells, TFR1 participates in iron-mediated resistance to cytarabine by regulating the entry of iron into the cells. These findings provide a foundation for further exploration of the molecular mechanisms involved in AML resistance to cytarabine.

1. Introduction

Acute myeloid leukemia (AML) is a malignant hematological disorder that arises from hematopoietic stem/progenitor cells in the bone marrow and has a relatively high incidence in adults [1–3]. The cornerstone of clinical treatment for AML is chemotherapy, which aims primarily to eradicate tumor cells through the induction of apoptosis. However, the emergence of apoptosis resistance in these tumor cells, often resulting from prolonged exposure to chemotherapy, significantly undermines the success of AML remission and leads to subsequent relapse [4–6].

TP53, a critical transcription factor, is involved in essential biological processes such as cell cycle arrest and apoptosis and can be activated by various stressors, including DNA damage, carcinogens, and nutrient depletion [7–9]. It is the most frequently mutated gene in human tumors, primarily through missense mutations in the coding region or complete deletions of the TP53 gene [10,11]. In acute myeloid leukemia (AML), TP53 mutations serve as predictors of resistance and recurrence, with mutations or loss closely linked to chemotherapy resistance, irrespective of age, karyotype, or other genetic markers [12–14]. Although TP53 mutations occur in less than 10% of newly diagnosed AML patients, their incidence is 25% in elderly patients and 30% in patients with therapy-related AML/myelodysplastic syndrome (t-AML/MDS) [15–18]. Cytarabine (Ara-C) has been the cornerstone of induction and consolidation therapy for AML since the 1960s [19]. Despite a high initial remission rate in newly diagnosed patients, more than 50% of those who achieve first complete remission are expected to relapse within three years [20]. The TP53 signaling pathway is pivotal for the cytotoxic effects of targeted therapies and chemotherapy in AML [21,22]. Clinical studies by Welch et al. [23] revealed a correlation between TP53 mutations during AML chemotherapy and treatment outcomes, a finding subsequently corroborated by experiments from Chang et al. [24]. Notably, the TP53 signaling pathway mediates both the efficacy of anti-AML therapies and the development of resistance [25].

Iron is a crucial element in various cellular processes, including DNA synthesis, oxygen transport, and ATP production [26]. Owing to their rapid proliferation and metastasis, tumor cells demand more iron than normal cells do [27]. Clinical studies have shown that genes associated with iron metabolism are upregulated during both the early and late stages of tumor development, further increasing the iron requirements of cancer cells [28,29]. In animal models, low-iron diets have been shown to delay tumor growth, underscoring the role of iron in tumor progression [30]. An imbalance in iron homeostasis is recognized as a metabolic hallmark of malignant tumor cells and is characterized by increased iron demand throughout the processes of tumor development, survival, proliferation, and metastasis [31]. Conversely, excessive iron can increase oxidative stress, resulting in damage to DNA, proteins, and lipids, which may lead to apoptosis, ferroptosis, and necrosis [32]. Zhou et al. [33] demonstrated that iron enhances the cytotoxic effects of chemotherapy by generating reactive oxygen species (ROS) through oxidative stress, thereby inhibiting the growth and metastasis of melanoma. The role of iron in tumor biology remains contentious and warrants further investigation. Notably, iron metabolism directly affects TP53 via heme, influencing the localization, stability, and function of the TP53 protein, which in turn regulates TP53 signaling [34]. This interaction was corroborated in the study by Calabreseden et al. [35], where the application of iron chelators to AML cells