Department of Gastroenterology, Endocrinology and Metabolism, Philipps University Marburg, Marburg, Germany.
Gut. 2013 Jul;62(7):1034-43. doi: 10.1136/gutjnl-2012-302577. Epub 2012 Jun 7.
Novel imaging methods based on specific molecular targets to detect both established neoplasms and their precursor lesions are highly desirable in cancer medicine. Previously, we identified claudin-4, an integral constituent of tight junctions, as highly expressed in various gastrointestinal tumours including pancreatic cancer. Here, we investigate the potential of targeting claudin-4 with a naturally occurring ligand to visualise pancreatic cancer and its precursor lesions in vitro and in vivo by near-infrared imaging approaches.
A non-toxic C-terminal fragment of the claudin-4 ligand Clostridium perfringens enterotoxin (C-CPE) was labelled with a cyanine dye (Cy5.5). Binding of the optical tracer was analysed on claudin-4 positive and negative cells in vitro, and tumour xenografts in vivo. In addition, two genetically engineered mouse models for pancreatic intraepithelial neoplasia (PanIN) and pancreatic cancer were used for in vivo validation. Optical imaging studies were conducted using 2D planar fluorescence reflectance imaging (FRI) technology and 3D fluorescence-mediated tomography (FMT).
In vitro, the peptide-dye conjugate showed high binding affinity to claudin-4 positive CAPAN1 cells, while claudin-4 negative HT1080 cells revealed little or no fluorescence. In vivo, claudin-4 positive tumour xenografts, endogenous pancreatic tumours, hepatic metastases, as well as preinvasive PanIN lesions, were visualised by FRI and FMT up to 48 h after injection showing a significantly higher average of fluorochrome concentration as compared with claudin-4 negative xenografts and normal pancreatic tissue.
C-CPE-Cy5.5 combined with novel optical imaging methods enables non-invasive visualisation of claudin-4 positive murine pancreatic tumours and their precursor lesions, representing a promising modality for early diagnostic imaging.
基于特定分子靶点的新型成像方法，既能检测已确立的肿瘤，也能检测其前体病变，这在癌症医学中是非常需要的。此前，我们发现紧密连接的组成部分紧密连接蛋白 4（claudin-4）在包括胰腺癌在内的各种胃肠道肿瘤中高度表达。在这里，我们通过近红外成像方法研究了用天然配体靶向 claudin-4 以可视化体外和体内胰腺癌及其前体病变的潜力。
用菁染料（Cy5.5）标记 claudin-4 配体产气荚膜梭菌肠毒素（C-CPE）的无毒 C 端片段。在体外分析光学示踪剂在 claudin-4 阳性和阴性细胞上的结合，以及体内肿瘤异种移植物的结合。此外，还使用两种用于胰腺上皮内瘤变（PanIN）和胰腺癌的基因工程小鼠模型进行体内验证。光学成像研究使用 2D 平面荧光反射成像（FRI）技术和 3D 荧光介导断层扫描（FMT）进行。
在体外，该肽-染料缀合物对 claudin-4 阳性 CAPAN1 细胞具有高结合亲和力，而 claudin-4 阴性 HT1080 细胞显示出很少或没有荧光。在体内，FRI 和 FMT 可检测到 claudin-4 阳性肿瘤异种移植物、内源性胰腺肿瘤、肝转移以及前侵袭性 PanIN 病变，在注射后 48 小时内显示出明显更高的荧光团浓度平均值，与 claudin-4 阴性异种移植物和正常胰腺组织相比。
C-CPE-Cy5.5 与新型光学成像方法相结合，可实现非侵入性可视化 claudin-4 阳性小鼠胰腺肿瘤及其前体病变，代表了早期诊断成像的有前途的模式。
