前列腺特异性膜抗原细胞外区域特异性的放射标记单克隆抗体的体外表征。

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Smith-Jones PM, Vallabahajosula S, Goldsmith SJ, Navarro V, Hunter CJ, Bastidas D, Bander NH

前列腺特异性膜抗原细胞外区域特异性的放射标记单克隆抗体的体外表征。

癌症决议2000年9月15日;60(18):5237-43。

PubMed ID

11016653 (PubMed视图

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摘要

前列腺特异性膜抗原(PSMA)是一种特征良好的细胞表面抗原，几乎所有前列腺癌(pca)都表达。(111) in -labeled 7E11单克隆抗体(mAb;ProstaScint;Cytogen, Princeton, NJ)，与PSMA的细胞内表位结合。这项工作报告了最近开发的三种结合PSMA胞外结构域(PSMAext)的单克隆抗体的体外表征。小鼠单抗J415、J533、J591和7E11用131I进行放射标记，并与LNCaP细胞基质进行竞争性和饱和结合研究。J415和J591与1,4,7,10-四氮杂环十二烷-N,N'，N "，N " '-四乙酸结合，用(111)In标记。在活的LNCaP细胞中评估了这些抗体的摄取和细胞加工。所有四种单克隆抗体都能被131I标记，特异性活性最高可达350 MBq/mg，没有或几乎没有明显的免疫反应性损失。竞争分析显示，J415和J591在与PSMAext抗原的结合上存在竞争。 J533 bound to a region close to the J591 binding epitope, but J533 did not interfere with J415 binding to PSMA. mAb 7E11 did not inhibit the binding of J415, J533, or J591 (or vice versa), consistent with earlier work that these latter mAbs bind PSMAext whereas 7E11 binds the intracellular domain of PSMA. Saturation binding studies demonstrated that J415 and J591 bound with a similar affinity (Kds 1.76 and 1.83 nM), whereas J533 had a lower affinity (Kd, 18 nM). In parallel studies, all four mAbs bound to a similar number of PSMA sites expressed by permeabilized cells (1,000,000-1,300,000 sites/cell). In parallel studies performed with viable LNCaP cells, J415, J533, and J591 bound to a similar number of PSMA sites (i.e., 600,000-800,000 sites/cell), whereas 7E11 bound only to a subpopulation of the available PSMA sites (95,000 sites/cell). This apparent binding of 7E11 to viable cells can be accounted for by a 5-7% subpopulation of permeabilized cells produced when the cells were trypsinized and suspended. Up to five DOTA chelates could be bound to either J415 or J591 without compromising immunoreactivity. A comparison of the cellular uptake and metabolic processing of the 131I- and (111)In-labeled antibodies showed a rapid elimination of 131I from the cell and a high retention of (111)In. All four mAbs recognized and bound to similar numbers of PSMAs expressed by ruptured LNCaP cells (i.e., the exposed intracellular and extracellular domains of PSMA). By comparison to J415 and J591, J533 had a lower binding affinity. Both J415 and J591 recognized and bound to the same high number of PSMAs expressed by intact LNCaP. By contrast, 7E11 bound to fewer sites expressed by intact LNCaP cells (i.e., the exposed extracellular domain of PSMA). Both J415 and J591 are promising mAbs for the targeting of viable PSMA-expressing tissue with diagnostic and therapeutic metallic radionuclides.

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药物	目标	种类	生物	药理作用	行动
Capromab pendetide	谷氨酸羧肽酶2	蛋白质	人类	是的	其他/未知	细节