Persson Morten, Juhl Karina, Rasmussen Palle, Brandt-Larsen Malene, Madsen Jacob, Ploug Michael, Kjaer Andreas
The Danish-Chinese Center for Proteases and Cancer.
Mol Pharm. 2014 Aug 4;11(8):2796-806. doi: 10.1021/mp500177c. Epub 2014 Jul 1.
The urokinase-type plasminogen activator receptor (uPAR) is implicated in cancer invasion and metastatic development in prostate cancer and provides therefore an attractive molecular target for both imaging and therapy. In this study, we provide the first in vivo data on an antimetastatic effect of uPAR radionuclide targeted therapy in such lesions and show the potential of uPAR positron emission tomography (PET) imaging for identifying small foci of metastatic cells in a mouse model of disseminating human prostate cancer. Two radiolabeled ligands were generated in high purity and specific activity: a uPAR-targeting probe ((177)Lu-DOTA-AE105) and a nonbinding control ((177)Lu-DOTA-AE105mut). Both uPAR flow cytometry and ELISA confirmed high expression levels of the target uPAR in PC-3M-LUC2.luc cells, and cell binding studies using (177)Lu-DOTA-AE105 resulted in a specific binding with an IC50 value of 100 nM in a competitive binding experiment. In vivo, uPAR targeted radionuclide therapy significantly reduced the number of metastatic lesions in the disseminated metastatic prostate cancer model, when compared to vehicle and nontargeted (177)Lu groups (p < 0.05) using bioluminescence imaging. Moreover, we found a significantly longer metastatic-free survival, with 65% of all mice without any disseminated metastatic lesions present at 65 days after first treatment dose (p = 0.047). In contrast, only 30% of all mice in the combined control groups treated with (177)Lu-DOTA-AE105mut or vehicle were without metastatic lesions. No treatment-induced toxicity was observed during the study as evaluated by observing animal weight and H&E staining of kidney tissue (dose-limiting organ). Finally, uPAR PET imaging using (64)Cu-DOTA-AE105 detected all small, disseminated metastatic foci when compared with bioluminescence imaging in a cohort of animals during the treatment study. In conclusion, uPAR targeted radiotherapy resulted in a significant reduction in the number of metastatic lesions in a human metastatic prostate cancer model. Furthermore, we have provided the first evidence of the potential for identification of small metastatic lesions using uPAR PET imaging in disseminated prostate cancer, illustrating the promising strategy of uPAR theranostics in prostate cancer.
尿激酶型纤溶酶原激活物受体（uPAR）与前列腺癌的侵袭和转移发展有关，因此是成像和治疗方面颇具吸引力的分子靶点。在本研究中，我们首次提供了uPAR放射性核素靶向治疗对这类病变抗转移作用的体内数据，并展示了uPAR正电子发射断层扫描（PET）成像在人前列腺癌播散小鼠模型中识别转移细胞小病灶的潜力。制备了两种高纯度和高比活度的放射性标记配体：一种uPAR靶向探针（（177）Lu-DOTA-AE105）和一种非结合对照（（177）Lu-DOTA-AE105mut）。uPAR流式细胞术和ELISA均证实PC-3M-LUC2.luc细胞中靶标uPAR的高表达水平，并通过（177）Lu-DOTA-AE105进行的细胞结合研究在竞争结合实验中得出特异性结合IC50值为100 nM。在体内，与使用生物发光成像的载体组和非靶向（177）Lu组相比，uPAR靶向放射性核素治疗显著减少了播散性转移性前列腺癌模型中的转移病灶数量（p < 0.05）。此外我们发现无转移生存期显著延长，在首次给药剂量后65天时所有小鼠中有65%没有任何播散性转移病灶（p = 0.047）。相比之下，用（177）Lu-DOTA-AE105mut或载体治疗的联合对照组中所有小鼠只有30%没有转移病灶。在研究过程中，通过观察动物体重和肾脏组织（剂量限制器官）的苏木精-伊红染色评估，未观察到治疗引起的毒性。最后，在治疗研究过程中，与一组动物中的生物发光成像相比，使用（64）Cu-DOTA-AE105的uPAR PET成像检测到了所有小的、播散性转移病灶。总之，uPAR靶向放射治疗导致人转移性前列腺癌模型中的转移病灶数量显著减少。此外，我们首次提供了在播散性前列腺癌中使用uPAR PET成像识别小转移病灶潜力的证据，说明了uPAR诊疗一体化在前列腺癌中的前景策略。
