核糖核苷酸还原酶 (RNR) 是脱氧核糖核苷三磷酸 (dNTP) 生产中的限速酶，而脱氧核糖核苷三磷酸 (dNTP) 是辐射损伤后 DNA 修复的重要底物。我们探索了 RNR 的放射增敏特性，并研究了选择性 RRM2 抑制剂 3-AP 作为治疗转移性 pNET 的放射增敏剂。我们研究了 RNR 亚基 RRM2 在胰腺神经内分泌 (pNET) 细胞中的作用以及体外对辐射的反应。我们还评估了选择性 RRM2 亚基抑制剂 3-AP 作为放射增敏剂治疗体内 pNET 转移。 RNR 亚基的敲低表明，RRM1 和 RRM2 亚基（而非 p53R3）在细胞增殖中发挥重要作用。 RRM2 抑制通过 ATM 和 DNA-PK 蛋白激酶而非 ATR 的磷酸化激活 DDR 通路。 RRM2 抑制还诱导 Chk1 和 Chk2 磷酸化，导致 G1/S 期细胞周期停滞。 RRM2 抑制使 pNET 细胞对放疗敏感并在体外诱导细胞凋亡。在体内，我们利用 pNET 皮下和肺转移模型来研究 RNR 靶向治疗和 3-AP 作为治疗 pNET 的放射增敏剂的基本原理。联合治疗显着增加了 BON（人 pNET）异种移植物的细胞凋亡，并显着减轻了肺转移的负担。总之，我们的结果表明，选择性 RRM2 抑制在体外和体内均可诱导转移性 pNET 的放射敏感性。因此，使用选择性 RRM2 抑制剂 3-AP 进行治疗是转移性 pNET 治疗药物中一种很有前途的放射增敏剂。版权所有 © 2024。由 Elsevier B.V. 出版。

Ribonucleotide Reductase (RNR) is a rate-limiting enzyme in the production of deoxyribonucleoside triphosphates (dNTPs), which are essential substrates for DNA repair after radiation damage. We explored the radiosensitization property of RNR and investigated a selective RRM2 inhibitor, 3-AP, as a radiosensitizer in the treatment of metastatic pNETs. We investigated the role of RNR subunit, RRM2, in pancreatic neuroendocrine (pNET) cells and responses to radiation in vitro. We also evaluated the selective RRM2 subunit inhibitor, 3-AP, as a radiosensitizer to treat pNET metastases in vivo. Knockdown of RNR subunits demonstrated that RRM1 and RRM2 subunits, but not p53R3, play significant roles in cell proliferation. RRM2 inhibition activated DDR pathways through phosphorylation of ATM and DNA-PK protein kinases but not ATR. RRM2 inhibition also induced Chk1 and Chk2 phosphorylation, resulting in G1/S phase cell cycle arrest. RRM2 inhibition sensitized pNET cells to radiotherapy and induced apoptosis in vitro. In vivo, we utilized pNET subcutaneous and lung metastasis models to examine the rationale for RNR-targeted therapy and 3-AP as a radiosensitizer in treating pNETs. Combination treatment significantly increased apoptosis of BON (human pNET) xenografts and significantly reduced the burden of lung metastases. Together, our results demonstrate that selective RRM2 inhibition induced radiosensitivity of metastatic pNETs both in vitro and in vivo. Therefore, treatment with the selective RRM2 inhibitor, 3-AP, is a promising radiosensitizer in the therapeutic armamentarium for metastatic pNETs.Copyright © 2024. Published by Elsevier B.V.