The early immature CD34⁺ acute myeloid leukemia (AML) cell subpopulation-acute myeloid leukemia progenitor cells (APCs), is often resistant to conventional chemotherapy, making them largely responsible for the relapse of AML. However, to date, the eradication of APCs remains a major challenge. We previously reported a naturally occurring secolignan- Peperomin E (PepE) and its analog 6-methyl (hydroxyethyl) amino-2, 6-dihydropeperomin E (DMAPE) that selectively target and induce oxidative stress-mediated apoptosis in KG-1a CD34⁺ cells (an APCs-like cell line) in vitro. We therefore further evaluated the efficacy and the mechanism of action of these compounds in this study. We found that PepE and DMAPE have similar potential to eliminate primary APCs, with no substantial toxicities to the normal cells in vitro and in vivo. Mechanistically, these agents selectively inhibit TrxR1, an antioxidant enzyme aberrantly expressed in APCs, by covalently binding to its selenocysteine residue at the C-terminal redox center. TrxR1 inhibition mediated by PepE (DMAPE) leads to the formation of cellular selenium compromised thioredoxin reductase-derived apoptotic protein (SecTRAP), oxidation of Trx, induction of oxidative stress and finally activation of apoptosis of APCs. Our results demonstrate a potential anti-APCs molecular target – TrxR1 and provide valuable insights into the mechanism underlying PepE (DMAPE)-induced cytotoxicity of APCs, and support the further preclinical investigations on PepE (DMAPE)-related therapies for the treatment of relapsed AML.

早期未成熟的CD34 ⁺急性骨髓性白血病（AML）细胞亚群-急性髓性白血病祖细胞（APC）通常对常规化疗耐药，这使它们在很大程度上是AML复发的原因。但是，迄今为止，根除APC仍然是一项重大挑战。我们以前曾报道过天然存在的Secolignan- Peperomin E（PepE）及其类似物6-甲基（羟乙基）氨基-2,6-dihydropeperominmin E（DMAPE），可选择性地靶向并诱导KG-1a CD34 ^+中氧化应激介导的细胞凋亡细胞（类APCs细胞系）进行体外培养。因此，我们在本研究中进一步评估了这些化合物的功效和作用机理。我们发现PepE和DMAPE具有消除初级APC的相似潜力，在体外和体内对正常细胞均无实质毒性。从机理上讲，这些试剂通过共价结合其在C上的硒代半胱氨酸残基来选择性抑制TrxR1（一种在APC中异常表达的抗氧化剂）。-末端氧化还原中心。PepE（DMAPE）介导的TrxR1抑制导致细胞硒受损的硫氧还蛋白还原酶衍生的凋亡蛋白（SecTRAP）的形成，Trx的氧化，氧化应激的诱导以及APC凋亡的活化。我们的结果证明了潜在的抗APCs分子靶标TrxR1，并提供了对PepE（DMAPE）诱导的APC细胞毒性的潜在机制的宝贵见解，并支持对PepE（DMAPE）相关疗法用于复发性AML的进一步临床前研究。