Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA.
Nucl Med Biol. 2010 Oct;37(7):785-94. doi: 10.1016/j.nucmedbio.2010.03.010.
Podoplanin/aggrus is a mucin-like sialoglycoprotein that is highly expressed in malignant gliomas. Podoplanin has been reported to be a novel marker to enrich tumor-initiating cells, which are thought to resist conventional therapies and to be responsible for cancer relapse. The purpose of this study was to determine whether an anti-podoplanin antibody is suitable to target radionuclides to malignant gliomas.
The binding affinity of an anti-podoplanin antibody, NZ-1 (rat IgG(2a)), was determined by surface plasmon resonance and Scatchard analysis. NZ-1 was radioiodinated with (125)I using Iodogen [(125)I-NZ-1(Iodogen)] or N-succinimidyl 4-guanidinomethyl 3-[(131)I]iodobenzoate ([(131)I]SGMIB-NZ-1), and paired-label internalization assays of NZ-1 were performed. The tissue distribution of (125)I-NZ-1(Iodogen) and that of [(131)I]SGMIB-NZ-1 were then compared in athymic mice bearing glioblastoma xenografts.
The dissociation constant (K(D)) of NZ-1 was determined to be 1.2 × 10(-10) M by surface plasmon resonance and 9.8 × 10(-10) M for D397MG glioblastoma cells by Scatchard analysis. Paired-label internalization assays in LN319 glioblastoma cells indicated that [(131)I]SGMIB-NZ-1 resulted in higher intracellular retention of radioactivity (26.3 ± 0.8% of initially bound radioactivity at 8 h) compared to that from the (125)I-NZ-1(Iodogen) (10.0 ± 0.1% of initially bound radioactivity at 8 h). Likewise, tumor uptake of [(131)I]SGMIB-NZ-1 (39.9 ± 8.8 %ID/g at 24 h) in athymic mice bearing D2159MG xenografts in vivo was significantly higher than that of (125)I-NZ-1(Iodogen) (29.7 ± 6.1 %ID/g at 24 h).
The overall results suggest that an anti-podoplanin antibody NZ-1 warrants further evaluation for antibody-based therapy against glioblastoma.
Podoplanin/aggrus 是一种高度表达于恶性神经胶质瘤的粘蛋白样唾液糖蛋白。已有报道称，Podoplanin 是一种新型标志物，可富集肿瘤起始细胞，这些细胞被认为能抵抗常规治疗，是癌症复发的原因。本研究旨在确定抗 Podoplanin 抗体是否适合将放射性核素靶向恶性神经胶质瘤。
通过表面等离子体共振和 Scatchard 分析确定抗 Podoplanin 抗体 NZ-1（大鼠 IgG2a）的结合亲和力。使用 Iodogen（125I-NZ-1（Iodogen））或 N-琥珀酰亚胺基 4-胍基甲基 3-[[131I]碘代苯甲酸酯（131I]SGMIB-NZ-1）对 NZ-1 进行放射性碘标记，并进行 NZ-1 的配对标记内化实验。然后比较荷胶质瘤异种移植的裸鼠中 125I-NZ-1（Iodogen）和 131I]SGMIB-NZ-1 的组织分布。
通过表面等离子体共振，NZ-1 的解离常数（K(D)）确定为 1.2×10(-10)M，通过 Scatchard 分析，D397MG 神经胶质瘤细胞的 K(D)为 9.8×10(-10)M。在 LN319 神经胶质瘤细胞中进行的配对标记内化实验表明，与 125I-NZ-1（Iodogen）相比，131I]SGMIB-NZ-1 导致放射性核素的细胞内保留率更高（8 小时时最初结合的放射性核素的 26.3±0.8%）。同样，荷 D2159MG 异种移植裸鼠体内的肿瘤摄取 131I]SGMIB-NZ-1（24 小时时 39.9±8.8%ID/g）也明显高于 125I-NZ-1（Iodogen）（24 小时时 29.7±6.1%ID/g）。
总体结果表明，抗 Podoplanin 抗体 NZ-1 值得进一步评估，以用于针对神经胶质瘤的抗体基础治疗。
