**1. Introduction**

Leukemia, especially acute myeloid leukemia (AML), is a lethal disease characterized by the accumulation of DNA-damaged immature myeloid precursors [1]. Only around 20% of adult cases are expected to survive past 5 years after diagnosis, and it is a leading cause of cancer death in young adults [2]. Although conventional chemotherapy is highly offensive against the bulk of leukemic cells, chemotherapy resistance in the refractory of AML is still a serious and common problem [2,3]. Thus, the development of new and specific therapeutic strategies that can overcome conventional drug resistance is still in demand.

In recent years, the development of nanomedicines as ferroptosis inducer in cancer cells has become a new promising approach to leukemia [4–6]. Ferroptosis is an iron-dependent, unique type of cell death due to excessive accumulation of toxic lipid reactive oxygen species (ROS) [7]. Ferroptosis can be stimulated by the GPX4 inhibitors (erastin, sorafenib, altretamine, etc.) and reagents that cause cellar iron overload (FeCl2, salinomycin, and hemoglobin), which leads to fueled ROS production and inhibition of tumor growth [8–11]. However, these compounds have already been challenged by the same resistance problem as that of traditional cancer drugs [12]. Iron nanoparticles are an emerging new ferroptosis inducer because it has the ability to increase iron levels and ROS. For example, a Fe3O4-based nanoparticle fabricated through self-assembly mechanism can generate ROS and can induce intracellular oxidative stress [6]. A Fenton-reaction-accelerable magnetic nanoparticle can be prepared to simultaneously enhance the local concentrations of Fe2<sup>+</sup>, Fe3<sup>+</sup>, and H2O2 to kill cancer cells [13]. Recently, a nanoparticle iron supplement, ferumoxytol, was found to have an antileukemia effect in vitro and in vivo in leukemia cells with a low level of ferroportin (FPN) by inducing ferroptosis [14].

However, as a new promising ferroptosis inducer, iron nanoparticle-induced cytotoxicity to leukemia cells at the transcriptomic level still remains unclear. This study thus investigated the effects of two kinds of iron nanoparticles, 2,3-Dimercaptosuccinic acid (DMSA)-coated Fe3O4 nanoparticles (FeNPs) and Prussian blue nanoparticles (PBNPs), on transcriptomic profiles of two leukemia cells (KG1a and HL60) by RNA-Seq. FeNPs can induce ROS generation through Fenton reactions, while PBNPs is an effective ROS scavenger with peroxidase (POD)-, catalase (CAT)-, and superoxide dismutase (SOD)-like activities [15]. HL60 is an AML cell with promyelocytic differentiation, while KG1a is a stem-like AML cell line that is resistant to chemotherapy and double negative T cell (DNT)-mediated cytotoxicity [2]. For example, fucoidan, a natural component of seaweeds with immunomodulatory and antitumor effects, was investigated in human AML cells. It can significantly increase apoptosis in HL60, but undifferentiated KG1a was resistant to the tumor inhibitory function of fucoidan [16].
