Unidade de Ciências Químicas e Radiofarmacêuticas, Instituto Tecnológico e Nuclear, Estrada Nacional, Sacavém, Portugal.
J Biol Inorg Chem. 2011 Dec;16(8):1141-53. doi: 10.1007/s00775-011-0803-x. Epub 2011 Jun 25.
Auger-emitting radionuclides such as (99m)Tc have been the focus of recent studies aiming at finding more selective therapeutic approaches. To explore the potential usefulness of (99m)Tc as an Auger emitter, we have synthesized and biologically evaluated novel multifunctional structures comprising (1) a pyrazolyl-diamine framework bearing a set of donor atoms to stabilize the M(CO)(3) (M is Re, (99m)Tc) core; (2) a DNA intercalating moiety of the acridine orange type to ensure close proximity of the radionuclide to DNA and to follow the internalization and subcellular trafficking of the compounds by confocal fluorescence microscopy; and (3) a bombesin (BBN) analogue of the type X-BBN[7-14] (where X is SGS, GGG) to provide specificity towards cells expressing the gastrin releasing peptide receptor (GRPr). Of the evaluated (99m)Tc complexes, Tc ( 3 ) containing the GGG-BBN[7-14] peptide showed the highest cellular internalization in GRPr-positive PC3 human prostate tumor cells, presenting a remarkably high nuclear uptake in the same cell line. Live-cell confocal imaging microscopy studies with the congener Re complex, Re ( 3 ), showed a considerable accumulation of fluorescence in the nucleus, with kinetics of uptake similar to that exhibited by Tc ( 3 ). Together, these data show that the acridine orange intercalator and the metal fragment are colocalized in the nucleus, which indicates that they remain connected despite the lysosomal degradation of Tc ( 3 )/Re ( 3 ). These compounds are the first examples of (99m)Tc bioconjugates that combine specific cell targeting with nuclear internalization, a crucial issue to explore use of (99m)Tc in Auger therapy.
近年来，人们一直致力于研究发射俄歇电子的放射性核素（如 99mTc），以期寻找更具选择性的治疗方法。为了探索 99mTc 作为俄歇电子发射体的潜在用途，我们合成并生物评价了一种新型多功能结构，该结构包含（1）一个带有一组供电子原子的吡唑基二胺骨架，以稳定 [M(CO)3]+（M 为 Re、99mTc）核心；（2）吖啶橙类型的 DNA 嵌入部分，以确保放射性核素与 DNA 紧密接近，并通过共聚焦荧光显微镜跟踪化合物的内化和细胞内转运；（3）X-BBN[7-14]（其中 X 为 SGS、GGG）类型的蛙皮素（BBN）类似物，以提供对表达胃泌素释放肽受体（GRPr）的细胞的特异性。在所评价的 99mTc 配合物中，含有 GGG-BBN[7-14]肽的 Tc(3)在 GRPr 阳性 PC3 人前列腺肿瘤细胞中表现出最高的细胞内化，在同一细胞系中表现出非常高的核摄取。与同系物 Re(3)的活细胞共聚焦成像显微镜研究表明，荧光在核内大量积聚，摄取动力学与 Tc(3)相似。综上所述，这些数据表明吖啶橙嵌入剂和金属片段在核内共定位，这表明尽管 Tc(3)/Re(3)发生溶酶体降解，但它们仍保持连接。这些化合物是首例将特异性细胞靶向与核内化相结合的 99mTc 生物缀合物，这是探索 99mTc 在俄歇治疗中应用的关键问题。
