PO.ET03.03 · 实验与分子治疗
靶向RRM2以增强TNBC对PARP抑制剂的敏感性
Targeting RRM2 to enhance PARP inhibitor sensitivity in TNBC
作者与单位 Authors & Affiliations
摘要 Abstract
中文摘要
三阴性乳腺癌(TNBC)仍是最具侵袭性和治疗难治性的乳腺癌亚型之一，主要归因于缺乏激素受体和HER2表达。Poly ADP-ribose polymerase (PARP)抑制剂如olaparib，通过利用同源重组修复缺陷肿瘤中的合成致死作用，在BRCA1/2突变型TNBC中展现出显著疗效。然而，对olaparib获得性耐药的出现显著限制了其长期临床应用。Ribonucleotide reductase (RR)是负责将核糖核苷酸转化为脱氧核糖核苷酸的限速酶，在DNA合成和细胞周期进程中发挥关键作用。Didox (3,4-dihydroxybenzohydroxamic acid)是一种ribonucleotide reductase抑制剂，兼具铁螯合和自由基清除活性。我们既往的工作发现RRM2亚基在TNBC细胞中上调并促成化疗耐药的发生。本研究探讨了使用Didox对RRM2的药理学抑制能否增强olaparib活性并减轻TNBC模型中的PARP抑制剂耐药。使用四种TNBC细胞系——MDA-MB-231、MDA-MB-468、MDA-MB-436和HCC1937——以涵盖BRCA野生型和BRCA突变型背景。通过基于MTS的IC₅₀测定量化对olaparib和Didox的细胞毒性应答，随后采用Chou-Talalay方法进行联合指数(CI)分析以评估潜在的药物协同作用。我们的数据显示，MDA-MB-436(BRCA1突变型)细胞对olaparib高度敏感，而MDA-MB-231和MDA-MB-468(BRCA1野生型)表现出显著耐药。Didox表现出中度的单药细胞毒性，但在耐药细胞系中显著增强了olaparib敏感性。Western blot分析显示联合治疗下DNA损伤信号增加，表明RRM2抑制增强了PARP抑制剂诱导的基因毒性应激。总之，这些发现支持了加用RR抑制剂以克服TNBC中PARP抑制剂耐药的治疗潜力，并值得进一步深入的机制和体内评估。
查看英文原文 English abstract
Triple-negative breast cancer (TNBC) remains one of the most aggressive and therapeutically refractory breast cancer subtypes, primarily due to the absence of hormone receptors and HER2 expression. Poly ADP-ribose polymerase (PARP) inhibitors such as olaparib have demonstrated substantial efficacy in BRCA1/2-mutated TNBC by exploiting synthetic lethality in tumors with defective homologous recombination repair. However, the emergence of acquired resistance to olaparib significantly limits its long-term clinical utility. Ribonucleotide reductase (RR), the rate-limiting enzyme responsible for converting ribonucleotides to deoxyribonucleotides, plays a pivotal role in DNA synthesis and cell-cycle progression. Didox (3,4-dihydroxybenzohydroxamic acid) is a ribonucleotide reductase inhibitor with additional iron-chelating and free-radical scavenging activities. Our previous work identified that the RRM2 subunit is upregulated in TNBC cells and contributes to the development of chemoresistance. The present study investigates whether pharmacologic inhibition of RRM2 using Didox can potentiate olaparib activity and mitigate PARP inhibitor resistance in TNBC models. Four TNBC cell lines-MDA-MB-231, MDA-MB-468, MDA-MB-436, and HCC1937-were utilized to encompass both BRCA-wild-type and BRCA-mutant backgrounds. Cytotoxic responses to olaparib and Didox were quantified by MTS-based IC₅₀ determination, followed by combination index (CI) analysis using the Chou-Talalay method to assess potential drug synergy. Our data show that MDA-MB-436 (BRCA1-mutant) cells were highly sensitive to olaparib, whereas MDA-MB-231 and MDA-MB-468 (BRCA1-wild-type) exhibited marked resistance. Didox displayed moderate single-agent cytotoxicity, however substantially enhanced olaparib sensitivity in resistant lines. Western blot analyses revealed increased DNA damage signaling under combination treatment, indicating that RRM2 inhibition augments PARP inhibitor-induced genotoxic stress. Collectively, these findings support the therapeutic potential of adding an RR inhibitor to overcome PARP inhibitor resistance in TNBC and warrant further in-depth mechanistic and in vivo evaluation.
利益披露 Disclosure
T. Islam, None.
H. L. Elford,
President ).
J. S. Faridi, None.