Noninvasive visualization of microRNA-155 in multiple kinds of tumors using a radiolabeled anti-miRNA oligonucleotide

Purpose: We investigated whether a Tc-99m radiolabeled anti-miRNA-155 oligonucleotide (AMO-155) could visualize the expression of miR-155 in multiple kinds of tumors in vivo. Methods: AMO-155 was chemically synthesized and modified with 2'-0-methyl(2'-OMe) and phosphorothioate (PS). It was radiolabeled with Tc-99m via the conjugation with NHS-MAG3 at 5' end. The characterization of radiolabeling and serum stability was evaluated using high performance liquid chromatography (HPLC) and agarose gel electrophoresis. The expression of C/EBP beta, one of the miR-155 target proteins, was assessed using Western blot. The cellular uptake and delivery of AMO-155 was further evaluated in tumor cells. Tc-99m-AMO-155 was tested in vivo in multiple tumor models, including miR-155 over-expressed and low-expressed tumor models. Finally, biodistribution of Tc-99m-AMO-155 was evaluated. Results: 99mTc-AMO-155 was prepared with high yield and radiochemical purity. It showed high stability in fresh human serum for 10 h. Tc-99m-AMO-155 displayed comparable capacity as unlabeled AMO-155 to increase the expression of C/EBP beta protein in MCF-7 cells. Tc-99m-AMO-155 showed an increased radioactive uptake in MCF-7 cells after 8 h of incubation, whereas no change of Tc-99m-pertechnetate uptake was observed. Carboxyfluorescein (FAM) labeled AMO-155 had higher fluorescent delivery than Control in HeLa and HepG2 cells by confocal microscopy. In miR-155 over-expressed tumor models, Tc-99m-AMO-155 showed significantly higher tumor accumulation than Tc-99m-Control. Furthermore, Tc-99m-AMO-155 was capable of discriminating between MCF-7 and MDA-MB-231 tumors based on their expression of miR-155. Conclusions: Our study successfully prepared and proved Tc-99m-AMO-155 as a prospective imaging agent for the noninvasive visualization of miR-155 expression in vivo. (C) 2015 Elsevier Inc. All rights reserved.National Natural Science Foundation of China [81441051, 81101065, 81472589]; Higher Education Doctoral Program of China Research Fund for New Teacher [20110001120043]; Beijing Capital Special Development Application Program [Z141107002514159]SCI(E)PubMedARTICLEzzbcaptain@yahoo.com.cn; miraclexxj@126.com; rongfu_wang2003@163.com2171-1784