Kang L, Huo Y, Wang R F, Zhang C L, Yan P, Xu X J
Department of Nuclear Medicine, Peking University First Hospital, Beijing 100034, China.
Department of Medical Molecular Biology, Beijing Institute of Biotechnology, Academy of Military Medical Sciences, Beijing 100850, China.
Beijing Da Xue Xue Bao Yi Xue Ban. 2018 Apr 18;50(2):326-330.
MicroRNA-155 (miR-155) is significantly highly expressed in breast cancer, lung cancer, liver cancer and other malignant tumors. This study was to design and construct a radiolabeled probe targeting miR-155 for in vivo imaging in breast cancer.
Anti-miR-155 oligonucleotide (AMO-155) was chemically synthesized with 2' OMe modification. Its 5' end was linked with acetyl amine group. After chelated with a bifunctional chelator NHS-MAG3, AMO-155 was radiolabeled with Tc using stannous chloride. The serum stability was evaluated at cellular level. In vivo imaging was performed in MCF-7 tumor bearing mice after the administration of Tc radiolabeled AMO-155 and scramble control probes, respectively. Furthermore, the blocked imaging of tumor bearing mice was obtained after the injection of unlabeled AMO-155 2 hours ahead. MCF-7 and MDA-MB-231 tumor bearing mice with different expression level of miR-155 were imaged, respectively. Quantitative real-time PCR (qRT-PCR) was used to identify the expression level of miR-155 in the bearing tumors.
Tc-AMO-155 was prepared with high radiolabeled efficiency (97%), radiochemical purity (greater than 98%), and radioactive specific activity (3.75 GBq/μg). Tc-AMO-155 was stable in fresh human serum for 12 hours. After the administration via tail vein, Tc-AMO-155 displayed significant accumulation in MCF-7 bearing tumors with high expression level of miR-155, whereas Tc-control showed little accumulation. After blocked with unlabeled AMO-155, the tumor could not be visualized clearly after the administration of Tc-AMO-155. Furthermore, Tc-AMO-155 could show the differential expression of miR-155 in vivo. MCF-7 tumor was shown with significantly higher radioactive accumulation than MDA-MB-231, based on its higher expression level of miR-155, which was verified by qRT-PCR.
Tc-labeled AMO-155 with chemical modification showed good serum stability and in vivo tumor targeting ability. This study provides a potential probe for in vivo imaging of breast cancer.
微小RNA-155（miR-155）在乳腺癌、肺癌、肝癌等多种恶性肿瘤中显著高表达。本研究旨在设计并构建一种靶向miR-155的放射性标记探针，用于乳腺癌的体内成像。
化学合成具有2'-O-甲基修饰的抗miR-155寡核苷酸（AMO-155），其5'端连接乙酰氨基。与双功能螯合剂NHS-MAG3螯合后，用氯化亚锡将AMO-155用锝进行放射性标记。在细胞水平评估其血清稳定性。分别给荷MCF-7肿瘤小鼠注射锝标记的AMO-155和乱序对照探针后进行体内成像。此外，在注射未标记的AMO-155 2小时后进行荷瘤小鼠的阻断成像。分别对miR-155表达水平不同的荷MCF-7和MDA-MB-231肿瘤小鼠进行成像。采用定量实时PCR（qRT-PCR）鉴定荷瘤组织中miR-155的表达水平。
制备的锝-AMO-155具有较高的放射性标记效率（97%）、放射化学纯度（大于98%）和放射性比活度（3.75 GBq/μg）。锝-AMO-155在新鲜人血清中12小时内稳定。经尾静脉给药后，锝-AMO-155在miR-155高表达的荷MCF-7肿瘤中显著蓄积，而锝-对照探针几乎没有蓄积。用未标记的AMO-155阻断后，注射锝-AMO-155后肿瘤无法清晰显影。此外，锝-AMO-155能够在体内显示miR-155的差异表达。基于其较高的miR-155表达水平，MCF-7肿瘤的放射性蓄积显著高于MDA-MB-231，这一点通过qRT-PCR得到验证。
经化学修饰的锝标记AMO-155具有良好的血清稳定性和体内肿瘤靶向能力。本研究为乳腺癌的体内成像提供了一种有潜力的探针。
