Use of the incretin hormone glucagon-like peptide-1 (GLP-1) for the detection of insulinomas:: initial experimental results
Use of the incretin hormone glucagon-like peptide-1 (GLP-1) for the detection of insulinomas:: initial experimental results
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DOI：
10.1007/s00259-002-0761-1
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发表时间：
2002-05-01
影响因子：
9.1
通讯作者：
Behr, TM
中科院分区：
文献类型：
--
作者：
Gotthardt, M;Fischer, M;Behr, TM
胰岛素瘤的非侵入性检测仍然是一个诊断问题，不能通过生长抑素受体血管造影来解决。我们研究了大鼠胰岛素瘤细胞系（RINm 5 F）中肠促胰岛素激素胰高血糖素样肽-1（GLP-1）的摄取和降解的生物学特性和特异性，以确定放射性标记的GLP-1是否适用于体内胰岛素瘤的特异性可视化。根据iodogen法对GLP-1（7-36）酰胺进行放射性碘标记。研究了RINm 5 F细胞摄取[I-125]GLP-1（7-36）酰胺的特异性。通过HPLC纯化细胞培养基中GLP-1（7-36）酰胺的降解产物。用Cf-252等离子体解吸质谱法测定了它们的质量和氨基酸序列。溶酶体降解被抑制，差速离心后，掺入溶酶体的放射性示踪剂的量进行了测定。在大鼠胰岛素瘤模型（NEDH大鼠和RINm 5 F细胞）中对[I-123]GLP-1（7-36）酰胺及其更稳定的激动剂[I-123]毒蜥外泌肽3进行了生物分布研究。胰岛素瘤细胞对放射性示踪剂的摄取在5分钟内达到最大值。过量的未标记肽可抑制放射性示踪剂的摄取。如果溶酶体降解受到抑制，[I-125]GLP-1（7-36）酰胺在细胞中蓄积。在细胞培养基中发现了肽的降解产物。我们确定了它们的质量并推导出它们的氨基酸序列。exendin 3的放射性标记比GLP-1更困难，因为其一级结构中缺乏酪氨酸。生物分布研究表明，快速血液清除和吸收的放射性示踪剂进入肿瘤和胰腺。还可以通过使用放射性碘标记的GLP-1（7-36）酰胺和毒蜥外泌肽3的体外放射照相术检测动物模型中的胰岛素瘤。GLP-1（7-36）酰胺通过受体介导的机制特异性内化到胰岛素瘤细胞中。我们的研究结果表明，GLP-1受体介导的血管造影术可能是一种新的方法，在体内检测胰岛素瘤。由于GLP-1的半衰期短。其更稳定的类似物exendin 3可能更适合体内的这一目的。
The non-invasive detection of insulinomas remains a diagnostic problem that is not solved by means of somatostatin receptor scintigraphy. We investigated the biokinetics and specificity of uptake and degradation of the incretin hormone glucagon-like peptide-1 (GLP-1) in a rat insulinoma cell line (RINm5F) in order to ascertain whether radiolabelled GLP-1 may be suitable for specific visualisation of insulinomas in vivo. GLP-1 (7-36)amide was radioiodinated according to the iodogen method. The specificity of the uptake of [I-125]GLP-1(7-36)amide by RINm5F cells was investigated. Degradation products of GLP-1 (7-36)amide in the cell medium were purified by HPLC. Their masses and amino acid sequences were determined by Cf-252-plasma desorption mass spectrometry. Lysosomal degradation was inhibited and after differential centrifugation the amount of radiotracer incorporated into lysosomes was determined. Biodistribution studies were performed in a rat insulinoma model (NEDH rats and RINm5F cells) with [I-123]GLP-1(7-36)amide and its more stable agonist [I-123]exendin 3. The uptake of radiotracer into insulinoma cells reached a maximum within 5 min. It was inhibited by an excess of unlabelled peptide. [I-125]GLP-1(7-36)amide accumulated in the cells if lysosomal degradation was inhibited. Degradation products of the peptide were found in the cell medium. We determined their mass and derived their amino acid sequence. Radiolabelling of exendin 3 was more difficult than that of GLP-1 because of the lack of tyrosine in its primary structure. Biodistribution studies showed rapid blood clearance and uptake of the radiotracer into the tumour and the pancreas. It was also possible to detect insulinomas in an animal model by external scintigraphy using radioiodinated GLP-1 (7-36)amide and exendin 3. GLP-1 (7-36)amide is specifically internalised into insulinoma cells by a receptor-mediated mechanism. Our results demonstrate that GLP-1 receptor-directed scintigraphy may be a new method for the detection of insulinomas in vivo. Due to the short half-life of GLP-1. its more stable analogue exendin 3 may better suit this purpose in vivo.