Zhang Meng-Zhi, Guan Yan-Xing, Zhong Jin-Xiu, Chen Xue-Zhong
Department of Nuclear Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, 330006, China.
Department of Nuclear Medicine, The First Affiliated Hospital of Nanchang University, Nanchang, 330006, China.
Transl Oncol. 2017 Aug;10(4):518-526. doi: 10.1016/j.tranon.2017.04.003. Epub 2017 May 27.
A micro-molecule peptide TP1623 of Tc-human epithelial growth factor receptor 2 (HER2) was prepared and the feasibility of using it as a HER2-positive molecular imaging agent for breast cancer was evaluated.
TP1623 was chemically synthesized and labeled with Tc. The labeling ratio and stability were detected. HER2 expression levels of breast cancer cells (SKBR3 and MDA-MB-231) and cell binding activity were measured. Biodistribution of TC-TP1623 in normal mice was detected. SKBR3/MDA-MB-231-bearing nude mice models with high/low expressions of HER2 were established. Tumor tissues were stained with hematoxylin-eosin (HE) and measured by immunohistochemistry to confirm the formation of tumors and HER2 expression. SPECT imaging was conducted for HER2-overexpressing SKBR3-bearing nude mice. The T/NT ratio was calculated and compared with that of MDA-MB-231-bearing nude mice with low HER2 expression. The competitive inhibition image was used to discuss the specific binding of Tc- TP1623 and the tumor.
The labeling ratio of Tc-TP1623, specific activity, and radiochemical purity (RCP) after 6 h at room temperature were (97.39 ± 0.23)%, (24.61 ± 0.06) TBq/mmol, and (93.25 ± 0.06)%, respectively. HER2 of SKBR3 and MDA-MB-231 cells showed high and low expression levels by immunohistochemistry, respectively. The in vitro receptor assays indicated that specific binding of TP1623 and HER2 was retained. Radioactivity in the brain was always at the lowest level, while the clearance rate of blood and the excretion rate of the kidneys were fast. HE staining showed that tumor cells were observed in SKBR3- and MDA-MB-231-bearing nude mice, with significant heteromorphism and increased mitotic count. The imaging of mice showed that targeted images could be made of Tc-TP1623 in high HER2-expressing tumors, while no obvious development was shown in tumors in low HER2-expressing nude mice. No development was visible in tumors in competitive inhibition of imaging, which indicates the combination of Tc-TP1623 and tumor was mediated by HER2.
High labeling ratio and specific activity of Tc-TP1623 is successfully prepared; it is a molecular imaging agent for HER2-positive tumors that has potential applicative value.
制备人表皮生长因子受体2（HER2）小分子肽TP1623，并评估其作为乳腺癌HER2阳性分子显像剂的可行性。
化学合成TP1623并用锝进行标记，检测标记率和稳定性。检测乳腺癌细胞（SKBR3和MDA-MB-231）的HER2表达水平及细胞结合活性。检测99mTc-TP1623在正常小鼠体内的生物分布。建立HER2高/低表达的荷SKBR3/MDA-MB-231裸鼠模型，对肿瘤组织进行苏木精-伊红（HE）染色及免疫组化检测以确认肿瘤形成及HER2表达情况。对HER2过表达的荷SKBR3裸鼠进行单光子发射计算机断层显像（SPECT）成像，计算肿瘤与非肿瘤组织放射性比值（T/NT），并与HER2低表达的荷MDA-MB-231裸鼠进行比较。采用竞争抑制显像探讨99mTc-TP1623与肿瘤的特异性结合。
99mTc-TP1623的标记率、比活度及室温放置6 h后的放射化学纯度分别为（97.39±0.23）%、（24.61±0.06）TBq/mmol及（93.25±0.06）%。免疫组化显示SKBR3和MDA-MB-231细胞的HER2分别呈高表达和低表达。体外受体分析表明TP1623与HER2的特异性结合得以保留。脑内放射性始终处于最低水平，血液清除率及肾脏排泄率较快。HE染色显示荷SKBR3和MDA-MB-231裸鼠体内有肿瘤细胞，具有明显异型性且有丝分裂计数增加。小鼠成像显示，99mTc-TP1623可对HER2高表达肿瘤进行靶向显像，而HER2低表达裸鼠肿瘤未见明显显像。竞争抑制显像时肿瘤未见显像，表明99mTc-TP1623与肿瘤的结合是由HER2介导的。
成功制备了标记率高、比活度高的99mTc-TP1623；它是一种对HER2阳性肿瘤具有潜在应用价值的分子显像剂。
