Radiosynthesize of a novel antisense imaging probe targeting lncRNA HOTAIR in malignant glioma.

Objectives: Long non-coding RNA (lncRNA) HOTAIR was manifested overexpressing and amplifying in many human carcinomas, which could serve as a useful target for cancer therapy. The 99mTc radiolabeled antisense oligonucleotides (ASON) could visualize the expression of HOTAIR and provide a diagnostic and therapeutic value for malignant tumors. The aim of this study was to radiosynthesize 99mTc with HOTAIR ASON and investigate the influence of the probe in cell proliferation, migration in malignant glioma cells, and in vivo imaging in malignant glioma xenographs.

Methods: The ASON probe targeting lncRNA HOTAIR was designed and modified. The radiolabeling of 99mTc with HOTAIR ASON was via the conjugation of bifunctional chelator HYNIC. Then, the probe was purified and tested for its radiolabeling efficiency and purity, as well as stability by iTLC and gel electrophoresis by Sephadex G25. The radiolabeled and unlabeled probe were transfected to malignant glioma cell line U87 with lipofectamine 2000 for the next experimental use. CCK-8 assay and cell scratch test were used to detect the cell proliferation and migration. Furthermore, in vivo tumor imaging was performed after U87 tumor bearing nude mice models established at 0.5, 1, 2, 4 and 6 hours after the probe intravenous injection. All data were analyzed by statistical software.

Results: The labeling efficiencies of 99mTc-HYNIC-HOTAIR ASON was 75.3% ± 5.6% and the radiochemical purity was more than 95%. The probe showed good stability within 12 hours for high radiochemical purity. Gel electrophoresis confirmed that the oligomer was successfully radiolabeled no significant degradation was found. When compared with untransfected ASON, the expression level of HOTAIR, cell proliferation and cell migration decreased in both transfected 99mTc labeled and unlabeled probe groups. The tumor was clearly shown at 2 hours post probe injection on SPECT/CT imaging, compared with control and blocking group.

Conclusions: HOTAIR ASON can inhibit the cell migration and cell proliferation of glioma U87 cell line. The 99mTc-HYNIC-HOTAIR ASON probe can be radiosynthesized and used in the in vivo, real-time imaging of lncRNA HOTAIR expression in malignant glioma.