一种作为潜在正电子发射断层显像（PET）成像剂的（18）F标记尿激酶型纤溶酶原激活剂（uPA）抑制剂的合成及体内临床前评估

Synthesis and in vivo preclinical evaluation of an (18)F labeled uPA inhibitor as a potential PET imaging agent.

作者信息

Ides Johan, Thomae David, Wyffels Leonie, Vangestel Christel, Messagie Jonas, Joossens Jurgen, Lardon Filip, Van der Veken Pieter, Augustyns Koen, Stroobants Sigrid, Staelens Steven

机构信息

Laboratory of Medicinal Chemistry, University of Antwerp (UAMC), Universiteitsplein 1, B-2610 Antwerp, Belgium; Laboratory of Cancer Research and Clinical Oncology, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium.

Molecular Imaging Center of Antwerp (MICA), University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium; Laboratory of Medicinal Chemistry, University of Antwerp (UAMC), Universiteitsplein 1, B-2610 Antwerp, Belgium.

出版信息

Nucl Med Biol. 2014 Jul;41(6):477-87. doi: 10.1016/j.nucmedbio.2014.03.019. Epub 2014 Mar 29.

DOI:10.1016/j.nucmedbio.2014.03.019

PMID:24768145

Abstract

INTRODUCTION

The urokinase plasminogen activator (uPA) system is a proteolytic cascade involved in tumor invasion and metastasis. uPA and its inhibitor PAI-1 are described as biomarkers for breast cancer with the highest level of evidence. The present study describes the synthesis and first in vivo application of an activity based uPA PET probe.

METHODS

Based on the design of a small irreversible and selective uPA inhibitor we developed an (18)F-labeled activity based probe for uPA imaging. Human uPA expressing MDA-MB-231-luc2-GFP cells were inoculated in the mammary fat pads of nude mice and treated with the probe once tumors reached a volume of 150mm(3). Scans were performed at 0.25, 0.75, 1.5, 4 and 6h post injection. To evaluate tumor uptake in vivo and ex vivo data were gathered. Biodistribution data of the organs and tissues of interest were collected at all time points. Due to a relatively low tumor uptake, probe stability was further evaluated.

RESULTS

The uPA targeting PET tracer was produced in high purity and with good specific radioactivity. In vivo PET data showed a maximum tumor uptake of 2,51±0,32 %ID/g at 4h p.i. A significant correlation between in vivo and ex vivo tumor uptake calculation was found (R=0.75; p<0.01). Due to a high blood signal at all time points, probe stability was further examined revealing high plasma protein binding and low plasma stability.

CONCLUSIONS

In vivo and ex vivo results clearly demonstrate that uPA expressing tumors can be detected with non-invasive PET imaging. Stability tests suggest that further optimization is needed to provide a better tumor-to-background contrast.

摘要

引言

尿激酶型纤溶酶原激活剂（uPA）系统是参与肿瘤侵袭和转移的蛋白水解级联反应。uPA及其抑制剂PAI-1被描述为乳腺癌证据水平最高的生物标志物。本研究描述了一种基于活性的uPA PET探针的合成及首次体内应用。

方法

基于一种小的不可逆且选择性uPA抑制剂的设计，我们开发了一种用于uPA成像的（18）F标记的基于活性的探针。将表达人uPA的MDA-MB-231-luc2-GFP细胞接种于裸鼠乳腺脂肪垫，待肿瘤体积达到150mm³时用该探针进行处理。在注射后0.25、0.75、1.5、4和6小时进行扫描。为评估体内肿瘤摄取情况，收集了体内和体外数据。在所有时间点收集感兴趣的器官和组织的生物分布数据。由于肿瘤摄取相对较低，进一步评估了探针稳定性。

结果

uPA靶向PET示踪剂以高纯度和良好的比放射性制备。体内PET数据显示注射后4小时肿瘤最大摄取量为2.51±0.32 %ID/g。体内和体外肿瘤摄取计算之间存在显著相关性（R = 0.75；p < 0.01）。由于所有时间点血液信号较高，进一步检查了探针稳定性，结果显示血浆蛋白结合率高且血浆稳定性低。