Santos Joana F, Laere Camille Van, Silva Catarina D, Cassells Irwin, Fernandes Célia, Raposinho Paula, Belchior Ana, Pinto Catarina I G, Mendes Filipa, Cawthorne Christopher, Ooms Maarten, Voorde Michiel Van de, Cleeren Frederik, Paulo António
C2TN - Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Bobadela LRS, 2695-066, Portugal.
Nuclear Medical Applications, Belgian Nuclear Research Centre (SCK CEN), Mol, Belgium.
EJNMMI Radiopharm Chem. 2025 Apr 11;10(1):18. doi: 10.1186/s41181-025-00339-6.
Strategies that focus on delivering Auger electron emitters to highly radiosensitive intracellular targets-such as the nucleus, cell membrane, or mitochondria-are gaining attention. Targeting these organelles could enhance therapeutic efficacy while minimizing off-target toxicity by allowing lower administered doses. In this context, this study explores the therapeutic potential of Tb-labeled radiocomplexes that integrate the mitochondria-targeting triphenylphosphonium (TPP) moiety with a prostate-specific membrane antigen (PSMA) targeting vector. The goal is to assess these dual-targeted radiocomplexes for their ability to deliver conversion electrons (CE) and Auger electrons (AEs) to prostate cancer (PCa) cells, specifically targeting the mitochondria to enhance therapeutic efficacy.
Two novel radiocomplexes, [Tb]Tb-TPP-PSMA and [Tb]Tb-TPP-G-PSMA, were synthesized with high radiochemical yield and purity. The proposed structures were validated using HPLC and ESI-MS analysis, with their Tb counterparts serving as reference compounds. In vitro experiments included cellular uptake, internalization, mitochondrial uptake, and DNA damage assays in PSMA-positive PCa cell lines. Clonogenic assays were performed to evaluate cell survival post-treatment. In vivo studies were conducted using SCID/Beige mice bearing PCa xenografts and involved µSPECT/CT imaging and radiometabolite analysis to evaluate biodistribution, pharmacokinetics, tumor uptake and in vivo stability of the radiocomplexes. Both [Tb]Tb-TPP-PSMA and [Tb]Tb-TPP-G-PSMA showed high radiochemical stability and were efficiently internalized by PSMA-positive cells, while showing minimal uptake in PSMA-negative cells. These dual-targeted radiocomplexes demonstrated significantly higher mitochondrial uptake compared to the non-TPP-containing [Tb]Tb-PSMA-617, leading to increased DNA damage and enhanced radiocytotoxicity. In vivo, the dual-targeted complexes demonstrated PSMA-specific tumor uptake and pharmacokinetics comparable to [Tb]Tb-PSMA-617, with effective clearance from non-target tissues.
The TPP-modified Tb-radiocomplexes effectively targeted the mitochondria of PSMA-positive PCa cells, leading to increased DNA damage and reduced cell viability compared to single-targeted radiocomplexes. These findings suggest that dual-targeting strategies, which combine PSMA and mitochondrial targeting, can enhance the therapeutic potential of radiopharmaceuticals for prostate cancer treatment.
专注于将俄歇电子发射体递送至高度放射敏感的细胞内靶点（如细胞核、细胞膜或线粒体）的策略正受到关注。靶向这些细胞器可通过降低给药剂量来提高治疗效果，同时将脱靶毒性降至最低。在此背景下，本研究探索了整合线粒体靶向三苯基膦（TPP）部分与前列腺特异性膜抗原（PSMA）靶向载体的铽标记放射性复合物的治疗潜力。目的是评估这些双靶向放射性复合物将转换电子（CE）和俄歇电子（AE）递送至前列腺癌（PCa）细胞的能力，特别是靶向线粒体以提高治疗效果。
合成了两种新型放射性复合物，[Tb]Tb-TPP-PSMA和[Tb]Tb-TPP-G-PSMA，具有高放射化学产率和纯度。使用HPLC和ESI-MS分析对所提出的结构进行了验证，其铽对应物用作参考化合物。体外实验包括PSMA阳性PCa细胞系中的细胞摄取、内化、线粒体摄取和DNA损伤测定。进行克隆形成试验以评估治疗后的细胞存活情况。体内研究使用携带PCa异种移植瘤的SCID/米色小鼠进行，包括μSPECT/CT成像和放射性代谢物分析，以评估放射性复合物的生物分布、药代动力学、肿瘤摄取和体内稳定性。[Tb]Tb-TPP-PSMA和[Tb]Tb-TPP-G-PSMA均显示出高放射化学稳定性，并被PSMA阳性细胞有效内化，而在PSMA阴性细胞中的摄取极少。与不含TPP的[Tb]Tb-PSMA-617相比，这些双靶向放射性复合物表现出显著更高的线粒体摄取，导致DNA损伤增加和放射细胞毒性增强。在体内，双靶向复合物表现出与[Tb]Tb-PSMA-617相当的PSMA特异性肿瘤摄取和药代动力学，且能从非靶组织有效清除。
TPP修饰的铽放射性复合物有效地靶向PSMA阳性PCa细胞的线粒体，与单靶向放射性复合物相比，导致DNA损伤增加和细胞活力降低。这些发现表明，结合PSMA和线粒体靶向的双靶向策略可增强放射性药物治疗前列腺癌的治疗潜力。
