Roodink Ilse, Raats Jos, van der Zwaag Bert, Verrijp Kiek, Kusters Benno, van Bokhoven Hans, Linkels Marianne, de Waal Robert M W, Leenders William P J
Department of Pathology, Radboud University Nijmegen Medical Centre, The Netherlands.
Cancer Res. 2005 Sep 15;65(18):8317-23. doi: 10.1158/0008-5472.CAN-04-4366.
We previously reported that during mouse embryogenesis, plexin D1 (plxnD1) is expressed on neuronal and endothelial cells. Endothelial cells gradually loose plxnD1 expression during development. Here we describe, using in situ hybridization, that endothelial plxnD1 expression is regained during tumor angiogenesis in a mouse model of brain metastasis. Importantly, we found PLXND1 expression also in a number of human brain tumors, both of primary and metastatic origin. Apart from the tumor vasculature, abundant expression was also found on tumor cells. Via panning of a phage display library, we isolated two phages that carry single-domain antibodies with specific affinity towards a PLXND1-specific peptide. Immunohistochemistry with these single-domain antibodies on the same tumors that were used for in situ hybridization confirmed PLXND1 expression on the protein level. Furthermore, both these phages and the derived antibodies specifically homed to vessels in brain lesions of angiogenic melanoma in mice after i.v. injection. These results show that PLXND1 is a clinically relevant marker of tumor vasculature that can be targeted via i.v. injections.
我们之前报道过，在小鼠胚胎发育过程中，丛状蛋白D1（plxnD1）在神经元和内皮细胞上表达。内皮细胞在发育过程中逐渐失去plxnD1表达。在此，我们利用原位杂交技术描述了，在脑转移小鼠模型的肿瘤血管生成过程中，内皮细胞的plxnD1表达得以恢复。重要的是，我们在许多原发性和转移性人脑肿瘤中也发现了PLXND1表达。除肿瘤血管外，在肿瘤细胞上也发现了丰富的表达。通过筛选噬菌体展示文库，我们分离出两种噬菌体，它们携带对PLXND1特异性肽具有特异性亲和力的单域抗体。用这些单域抗体对用于原位杂交的相同肿瘤进行免疫组织化学，证实了PLXND1在蛋白水平的表达。此外，静脉注射后，这些噬菌体和衍生抗体都能特异性归巢到小鼠血管生成性黑色素瘤脑损伤部位的血管。这些结果表明，PLXND1是肿瘤血管的一个临床相关标志物，可通过静脉注射进行靶向治疗。
