Radiosynthesis of A Novel Antisense Imaging Probe Targeting LncRNA HOTAIR in Malignant Glioma

Background: Long non-coding RNA (lncRNA) HOTAIR was manifested amplifying in many human carcinomas, which could serve as a useful target for cancer therapy. The 99m Tc radiolabeled antisense oligonucleotides (ASON) could visualize the expression of HOTAIR and provide a diagnostic value for malignant tumors. The aim of this study was to radiosynthesis 99m Tc with HOTAIR ASON and investigate the in vivo imaging in malignant glioma xenografts. Methods: : The ASON targeting lncRNA HOTAIR as well as mismatched ASON probe (ASONM) were designed and modified. The radiolabeling of 99m Tc with two probes were via the conjugation of bifunctional chelator HYNIC. Then probes were purified by Sephadex G25 and tested for their radiolabeling efficiency and purity, as well as stability by ITLC and gel electrophoresis. Then the radiolabeled probes were transfected with lipofectamine 2000 for cellular uptake test and the next experimental use. Furthermore, biodistribution study and SPECT imaging were performed at different times after probes were intravenously injected in glioma tumor-bearing mice models. All data were analyzed by statistical software. Results: : The labeling efficiencies of 99m Tc-HYNIC-ASON and 99m Tc-HYNIC-ASONM measured by ITLC were (91 ±1.5) % and (90 ±0.6) %, respectively, and the radiochemical purity were more than 89%. The probes showed good stability within 12 hours. Gel electrophoresis confirmed that the oligomers were successfully radiolabeled no significant degradation was found. Cellular uptake experiment showed that liposomes had the ability to carry probes into cells. Biodistribution study demonstrated that liposome coated 99m Tc-HYNIC-ASON had significantly higher uptake in the tumor and higher T/M ratio than the mismatched group. Meanwhile, the tumor was clearly shown at 1-hour post probe injection of liposome coated 99m Tc-HYNIC-ASON on SPECT/CT imaging, no tumor was seen in mismatched and blocking group. Conclusion: The liposome encapsulated 99m Tc-HYNIC-ASON probe can be used in the in vivo, real-time imaging of lncRNA HOTAIR expression in malignant glioma.