title: Magnetic resonance tumor targeting imaging using gadolinium labeled human telomerase reverse transcriptase antisense probes.
abstract: To develop a molecular probe for MRI detection of human tumor telomerase reverse transcriptase (hTERT) mRNA expression. Uniformly phosphorothioate-modified hTERT antisense oligonucleotide (ASON) homing hTERT mRNA was labeled with gadolinium (Gd) through the bifunctional chelator 1,4,7, 10-tetraazacyclododecane-N, N', N'', N'''-tetraacetic acid (DOTA) stirred within 45 minutes at 60 °C. The Gd labeled probes were characterized in vitro. The cellular uptake rate and biodistribution of (99m) Tc-DOTA-ASON was measured instead of that of Gd-DOTA-ASON. A549 lung adenocarcinoma model was established in BALB/c nude mice and Gd-DOTA-ASON was injected intraperitoneally and MR images were acquired using 7.0T Micro-MRI (Bruker Biospec, Ettlingen, Germany) at different time points. Immunohistochemical analysis of telomerase activity of each xenograft was operated two days after in vivo imaging. The binding efficiency of Gd-DOTA-ASON reached as high as 71.7 ± 4.5% (n = 6). Gd-DOTA-ASON displayed perfect stability in fresh human serum at 37 °C for 24 h. Compared with normal lung cells, A549 cells showed an obviously higher uptake of (99m) Tc-DOTA-ASON than that of lung cells (10.5 ± 2.7% vs. 4.8 ± 2.6%, P < 0.05). The signal intensity of A549 xenografts can be enhanced by Gd-DOTA-ASON and the signal to noise ratio (SNR) of tumor to muscle reached 2.37 and maintained a relatively high level within 6 h after injection. The activity of hTERT in A549 tumors can be suppressed by Gd-DOTA-ASON in pathological slices. The results of this study show that Gd-DOTA-ASON can be a promising intracellular MR contrast probe for targeting telomerase-positive carcinomas.
authors.affiliation: Department of Radiology, West China Hospital of Sichuan University, Chengdu, China.
authors.forename: Bing Xiu
authors.initials: BX
authors.lastname: Ren
authors.forename: Fan
authors.initials: F
authors.lastname: Yang
authors.forename: Gao Hong
authors.initials: GH
authors.lastname: Zhu
authors.forename: Zi Xing
authors.initials: ZX
authors.lastname: Huang
authors.forename: Hua
authors.initials: H
authors.lastname: Ai
authors.forename: Rui
authors.initials: R
authors.lastname: Xia
authors.forename: Xi Jiao
authors.initials: XJ
authors.lastname: Liu
authors.forename: Man
authors.initials: M
authors.lastname: Lu
authors.forename: Bin
authors.initials: B
authors.lastname: Song
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis*; D000077192:Adenocarcinoma of Lung; D000818:Animals; D045744:Cell Line, Tumor; D006571:Heterocyclic Compounds; D006801:Humans; D008175:Lung Neoplasms / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008819:Mice, Nude; D016376:Oligonucleotides, Antisense; D009942:Organometallic Compounds; D012333:RNA, Messenger / Q000378:metabolism; D059629:Signal-To-Noise Ratio; D019098:Telomerase / Q000235:genetics / Q000378:metabolism*
chemical_list: D006571:Heterocyclic Compounds; D016376:Oligonucleotides, Antisense; D009942:Organometallic Compounds; D012333:RNA, Messenger; C050823:gadolinium 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetate; C509186:TERT protein, human; D019098:Telomerase