Preparation and quality control of 99mTc labeled MDR1 oligonucleotide DNAs / 生物医学工程学杂志

The aim of this study is to explore the optimal labeling condition of technetium-99m labeled antisense oligonucleotides (ASON) DNA and sense oligonueleotides (SON) DNA against multi-drug resistance gene-1 (MIDR1) mRNA, to prepare its two-step icefrozen kits, and to perform the quality control of technetium-99m labeled ASON and SON DNAs and its two-step icefrozen kits. A 20 mer single-stranded ASON sequence and its SON sequence against MDR1 mRNA were synthesized respectively, both of the ASON and SON DNAs were uniform phosphorothioated for this investigation with a primary amine on the 5'-end via a six-carbon alkyl linker, and then were labeled with technetium-99m by conjugating with the bifunctional chelator S-Acetyl NHS-MAG3 to form ASON- and SON-MAC3 DNAs. The optimal labeling condition was explored by varying the amount of ASON- and SON-MAG3 DNAs, SnCl2.2H2O and buffer, the pH value in the reaction medium was also adjusted. The technetium-99m labeled ASON and SON DNAs' two-step icefrozen kits were developed. The radiochemical purities, labeling stability of ASON- and SON-MAG3 DNAs in vivo and vitro were measured, and stability of the two-step icefrozen kits were also studied. The recycled rates of ASON- and SON-MAG3 DNAs were over 70% (n >6), the two-step icefrozen kits of ASON- and SON-MAG3 DNAs were colourless ice crystal. The radiochemical purities of technetium-99m labeled ASON- and SON-MAG3 DNAs were over 92 %. The radiochemical purities were over 90% after stored at room temperature for 24 hours. The kits were stable within 6 months when stored at 0 degrees C, the radiochemical purities of technetium-99m labeled ASON- and SON-MAG3 DNAs were still over 90%. The two-step icefrozen kits of ASON- and SON-MAG3 DNAs were successfully developed. The radiochemical purities were all over 90%. The labeling method was simple, feasible and efficient with good stability.

Experimental study of 99mTc-antisense DNA for tumor imaging / 生物医学工程学杂志

This study was performed to explore the feasibility of antisense imaging with radiolabeled antisense oligonucleotides DNA in tumored nude mice in vivo. Two different tumor cell lines, KB-G2 and KB-31,were used; both antisense and control sense DNAs were administrated intratumorally. The hybridization activities analysis of MAG3 conjugated DNAs oligonucleotides was demonstrated by Polyacrylamide Gel Electrophoresis. The whole body imaging was performed 22 h after administration of radiolabeled antisense and control sense DNAs at 1.0 microg DNAs (100 microCi) in 100 microl per animal. Then the animals were sacrificed at 24 h after administration and the organs and tissues were dissected and weighed; the radioactivity of each sample was detected by r-counter; injection dose percentage per gram tissue (%ID/g) was calculated and the biodistribution obtained. Both MAGS conjugated oligonucleotides DNAs and natural oligonucleotides DNAs have the same hybridization activities. The whole body images demonstrate improved targeting of antisense DNAs vs sense DNAs in the KB-G2 but not the KB-31 animals. Tumor levels in the KB-G2 animals were significantly higher for the antisense DNAs vs sense DNAs (14.7 vs 8.5% ID/g) while this difference (8.6 vs 4.3% ID/g) was insignificant in the KB-31 animals. Evidence for tumor targeting in vivo by an antisense in that mechanism has been obtained; statistically higher tumor accumulations of the 99mTc-antisense DNA were observed when compared to the control 99mTc-sense DNA. The successful localization of antisense DNA in tumor demonstrates that antisense tumor targeting in vivo is feasible even though improvement in tumor delivery and normal tissue clearance are needed for practical antisense imaging.