In Vivo Diagnosis of Gene Localization and Expression by Nuclear Medicine Modality

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The aim of this investigation is to develop nuclear medicine techniques for non-invasive diagnosis of gene localization and expression. Gene here means the one injected for gene therapy or the other over-expressed due to the disease. Using human epidermoid tumor cell line ; KB-31 and its mdr-1 transfected cell line ; KB-G2 carried out the study. By co-working with Dr. Donald J Hnatowich, Professor of Massachusetts Medical School, the following results were obtained;1. Antisense (AS) and sense (S) oligonucleotides related to mdr-1 were synthesized and modified (all phosphothiolated) and then, labeled with Tc-99m via MAG3 or HYNIC ligands. Tc-99m-AS and Tc-99m-S were obtained with high specific activity without loosing their antisense-binding affinity.2. KB-31 or KB-G2 were treated with AS or S, followed by incubation with Tc-99m-MIBI, which is to evaluate P-glycoprotein (mdr-1 expression) function. The KB-G2 treated with AS suppressed the P-gp function, while it was not shown in KB-G2 treated by S. KB-31 did not show any influence by treating with AS or S. These results indicated the antisense effect of AS oligonucleiotied we used.3. Tc-99m-AS was accumulated in KB-G2 but not in KB-31, while Tc-99m-S was not taken up either in KB-G2 or KB-31. These results indicated that AS was accumulated into the cell by antisense effect.4. Tc-99m-AS or Tc-99m-S was injected into the mice bearing KB-G2 or KB-31. The uptake of Tc-99m-AS in the KB-G2 tumor was significantly higher than that in the KB-31 tumors. Tc-99m-AS uptake in KB-G2 tumor was significantly higher than Tc-99m-S. These results indicated that Tc-99m-AS was localized into the mdr-1-tumors specifically by antisense erect.All these results would lead the success for the antisense imaging.