Synthesis and Cellular Uptake of 2‘-Substituted Analogues of (E)-5-(2-[¹²⁵I]Iodovinyl)-2‘-deoxyuridine in Tumor Cells Transduced with the Herpes Simplex Type-1 Thymidine Kinase Gene. Evaluation as Probes for Monitoring Gene Therapy

Abstract

A useful synthetic methodology was developed to synthesize and radiolabel a series of (E)-5-(2-[125I]iodovinyl)uracil nucleoside substrates for herpes simplex virus type-1 thymidine kinase (HSV-1 TK). (E)-5-(2-[125I]Iodovinyl)-2'-deoxyuridine ([125I]IVDU, 10), (E)-5-(2-[125I]iodovinyl)-2'-fluoro-2'-deoxyuridine ([125I]IVFRU, 11), (E)-5-(2-[125I]iodovinyl)-2'-fluoro-2'-deoxyarabinouridine ([125I]IVFAU, 12), and (E)-5-(2-[125I]iodovinyl)arabinouridine ([125I]IVAU, 13) were synthesized in 63-83% radiochemical yield by reaction of the unprotected (E)-5-(2-(trimethylsilyl)vinyl) precursors (6-9) with [125I]ICl. Cellular uptake of these labeled compounds (10-13) was evaluated in vitro. All compounds showed minimal uptake in the KBALB cell line. However, increased uptake was observed for all compounds in KBALB-STK cells which are transduced with a replication incompetent Moloney murine leukemia virus vector encoding the HSV-1 TK gene. The results indicate that uptake of these compounds in KBALB-STK cells is variable and highly dependent on the nature of the sugar 2'-substituent. When a fluoro (12) or a hydroxy (13) substituent is present in the arabinofuranosyl (up) configuration at the 2'-position, there is diminished cellular uptake in KBALB-STK cells relative to hydrogen (10) or fluorine (11) in the ribofuranosyl (down) configuration at the 2'-position. Our results indicate that radiolabeled IVFRU (11) is most promising for further in vivo studies.

5-Alkynyl Analogs of Arabinouridine and 2‘-Deoxyuridine: Cytostatic Activity against Herpes Simplex Virus and Varicella-Zoster Thymidine Kinase Gene-Transfected Cells

“…This type of information is useful for the design of chemotherapeutic agents to treat viral diseases and radiopharmaceutical agents to monitor viral gene expression that is beneficial in the gene therapy of cancer. [11][12][13][14][15][16] Accordingly, biological evaluations were performed using an extensive battery of antiviral assays (see Tables 1-5) and specific cell lines, both wild-type and those that were transfected with a viral thymidine kinase gene (HSV-1tk + , HSV-2tk + , or VZVtk + ). The 2′,3′,5′-tri-O-acetyl (TA) derivative (IEAU-TA) of 5-(2-iodoethynyl)-arabinouridine (IEAU) was originally prepared with the view that IEAU-TA would then serve as a prodrug that undergoes in vivo cleavage by plasma esterases to release the parent compound.…”

Imaging adenoviral-directed reporter gene expression in living animals with positron emission tomography

“…The herpes simplex virus 1 thymidine kinase reporter gene (HSV1-tk) has been explored by several groups for the purposes of imaging reporter gene expression (8)(9)(10)(11)(12)(13)(14)(15). HSV1-TK enzyme has relaxed substrate specificity as compared with mammalian thymidine kinases and can phosphorylate acycloguanosine and uracil derivatives (16,17).…”

The imaging continuum: bench to biomarkers to diagnostics

“…Before satisfactory methods for imaging were developed, 131 I was already being used to treat thyroid cancer. 134 Technetium ( 99m Tc), the most widely used radioisotope for diagnostics imaging (employed in 85% of all diagnostic imaging procedures), 135 is generated from 99 Mo.…”