For effective Auger therapy of cancer, the Auger-electron emitters must be delivered to the tumor cells in close proximity to a radiosensitive cellular target. Nuclear DNA is considered the most relevant target of Auger electrons to have augmented radiotoxic effects and significant cell death. However, there is a growing body of evidence that other targets, such as the mitochondria, could be relevant subcellular targets in Auger therapy. Thus, we developed dual-targeted 99mTc(I) tricarbonyl complexes containing a triphenylphosphonium (TPP) moiety to promote accumulation of 99mTc in the mitochondria, and a bombesin peptide to provide specificity towards the gastrin releasing peptide receptor (GRPr) overexpressed in prostate cancer cells. The designed dual-targeted complex, 99mTc-TPP-BBN, is efficiently internalized by human prostate cancer PC3 cells through a specific GRPr-mediated mechanism of uptake. Moreover, the radioconjugate provided an augmented accumulation of 99mTc in the mitochondria of the target tumor cells, most probably following its intracellular cleavage by cathepsin B. In addition, 99mTc-TPP-BBN showed an enhanced ability to reduce the survival of PC3 cells, in a dose-dependent manner.
为了有效地进行癌症奥格尔治疗,奥格尔电子发射体必须被输送到肿瘤细胞中,靠近一个放射敏感的细胞靶点。核DNA被认为是奥格尔电子最相关的靶点,具有增强的放射毒性效应和显著的
细胞死亡。然而,越来越多的证据表明,其他靶点,如线粒体,可能是奥格尔治疗中相关的亚细胞靶点。因此,我们开发了含
三苯基膦(
TPP)基团的双靶向99mTc(I)三羰基合
金物质,以促进99mTc在线粒体中的积累,并使用波美斯因肽提供特异性,以靶向前列腺癌细胞中过表达的胃泌素释放肽受体(GRPr)。设计的双靶向复合物99mTc-
TPP-BBN通过特异性GRPr介导的摄取机制有效内化到人前列腺癌PC3细胞中。此外,放射结合物在靶肿瘤细胞的线粒体中提供了99mTc的增强积累,很可能是通过其在细胞内被半胱
氨酸
蛋白酶B剪切而实现的。此外,99mTc-
TPP-BBN显示出增强的能力,以剂量依赖的方式降低PC3细胞的存活率。