N-glycosylation and microtubule integrity are involved in apical targeting of prostate-specific membrane antigen:: implications for immunotherapy
N-glycosylation and microtubule integrity are involved in apical targeting of prostate-specific membrane antigen:: implications for immunotherapy
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DOI：
10.1158/1535-7163.mct-04-0171
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发表时间：
2005-05-01
影响因子：
5.7
通讯作者：
Rajasekaran, AK
中科院分区：
文献类型：
--
作者：
Christiansen, JJ;Rajasekaran, SA;Rajasekaran, AK
前列腺特异性膜抗原（PSMA）是前列腺癌细胞中表达的重要生物标志物，其水平与肿瘤分级成正比。膜关联以及与疾病阶段的相关性预示着 PSMA 作为基于抗体的治疗的抗原靶点的有希望的作用。这种模式的成功应用需要对目标抗原的亚细胞定位和运输有详细的了解。在这项研究中，我们发现 PSMA 主要在前列腺上皮细胞和分化良好的 Madin-Darby 犬肾细胞的顶端质膜中表达。我们表明，PSMA 直接靶向顶端表面，并且分类到适当的高尔基体后囊泡取决于蛋白质的 N-糖基化。微管细胞骨架的完整性对于 PSMA 在顶端质膜结构域的递送和保留也至关重要，因为用诺考达唑或常用化疗长春花生物碱破坏微管的稳定性会导致 PSMA 的基底外侧表达，并增加基底外侧结构域对抗 PSMA 抗体的摄取。这些结果可能与基于 PSMA 的免疫治疗和成像策略具有重要相关性，因为前列腺癌细胞即使在转移到远端部位后也可以保持分化良好的形态。与基底外侧表面上的抗原相反，顶端抗原通过紧密连接与循环分离，紧密连接限制了分子穿过上皮的运输。因此，在顶端质膜上表达的抗原不会暴露于静脉内施用的试剂。将 PSMA 极性从顶端逆转为基底外侧的能力可能对使用 PSMA 作为治疗靶点具有重大意义。
Prostate-specific membrane antigen (PSMA) is an important biomarker expressed in prostate cancer cells with levels proportional to tumor grade. The membrane association and correlation with disease stage portend a promising role for PSMA as an antigenic target for antibody-based therapies. Successful application of such modalities necessitates a detailed knowledge of the subcellular localization and trafficking of target antigen. In this study, we show that PSMA is expressed predominantly in the apical plasma membrane in epithelial cells of the prostate gland and in well-differentiated Madin-Darby canine kidney cells. We show that PSMA is targeted directly to the apical surface and that sorting into appropriate post-Golgi vesicles is dependent upon N-glycosylation of the protein. Integrity of the microtubule cytoskeleton is also essential for delivery and retention of PSMA at the apical plasma membrane domain, as destabilization of microtubules with nocodazole or commonly used chemotherapeutic Vinca alkaloids resulted in the basolateral expression of PSMA and increased the uptake of anti-PSMA antibody from the basolateral domain. These results may have important relevance to PSMA-based immunotherapy and imaging strategies, as prostate cancer cells can maintain a well-differentiated morphology even after metastasis to distal sites. In contrast to antigens on the basolateral surface, apical antigens are separated from the circulation by tight junctions that restrict transport of molecules across the epithelium. Thus, antigens expressed on the apical plasma membrane are not exposed to intravenously administered agents. The ability to reverse the polarity of PSMA from apical to basolateral could have significant implications for the use of PSMA as a therapeutic target.