Previous studies highlighted that aminopeptidase N (APN)/CD13 acts as a scavenger in the survival of hepatocellular carcinoma (HCC) stem cells by reducing reactive oxygen species (ROS) levels. Hence, it has been proposed that APN/CD13 inhibition can increase cellular ROS levels and sensitize cells to chemotherapeutic agents. Although ubenimex, also known as bestatin, competitively inhibits proteases such as APN/CD13 on the cellular membrane and it is clinically used for patients with acute myeloid leukemia and lymphedema, research has demonstrated that higher concentrations of the agent induce the death of APN/CD13⁺ HCC stem cells. In this study, we developed a poly(ethylene glycol)-poly(lysine) block copolymer-ubenimex conjugate (PEG-b-PLys(Ube)) to increase the efficacy of reagents in APN/CD13⁺ cancer stem cells. Exposure to PEG-b-PLys(Ube) increased the intracellular ROS concentration by inhibiting APN enzyme activity, permitting the induction of apoptosis and attenuation of HCC cell proliferation. In addition, PEG-b-PLys(Ube) exhibited a relatively stronger antitumor effect in mice than PEG-b-PLys alone or phosphate-buffered saline. Moreover, an isobologram analysis revealed that combinations of fluorouracil, cisplatin, or doxorubicin with PEG-b-PLys(Ube) exhibited synergistic effects. This study demonstrated that PEG-b-PLys(Ube) does not impair the properties of ubenimex and exerts a potent antitumor effect.

中文翻译：

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聚（乙二醇）-聚（赖氨酸）嵌段共聚物-ubenimex 共轭物靶向氨肽酶 N 并在肝细胞癌干细胞中发挥抗肿瘤作用。

先前的研究强调，氨肽酶 N (APN)/CD13 通过降低活性氧 (ROS) 水平，在肝细胞癌 (HCC) 干细胞的存活中充当清道夫。因此，有人提出抑制 APN/CD13 可以增加细胞 ROS 水平并使细胞对化学治疗剂敏感。虽然ubenimex，也称为bestatin，竞争性抑制细胞膜上的APN/CD13等蛋白酶，临床上用于急性髓系白血病和淋巴水肿患者，但研究表明，较高浓度的药物会诱导APN/CD13死亡⁺ HCC 干细胞。在本研究中，我们开发了一种聚（乙二醇）-聚（赖氨酸）嵌段共聚物-ubenimex 共轭物（PEG-b-PLys(Ube)），以提高 APN/CD13 ⁺中试剂的功效癌症干细胞。暴露于 PEG-b-PLys(Ube) 通过抑制 APN 酶活性增加细胞内 ROS 浓度，从而诱导细胞凋亡和减弱 HCC 细胞增殖。此外，与单独使用 PEG-b-PLys 或磷酸盐缓冲盐水相比，PEG-b-PLys(Ube) 在小鼠中表现出相对更强的抗肿瘤作用。此外，等效线图分析表明，氟尿嘧啶、顺铂或多柔比星与 PEG-b-PLys(Ube) 的组合表现出协同作用。该研究表明 PEG-b-PLys(Ube) 不会损害 ubenimex 的特性并发挥有效的抗肿瘤作用。