(A) The sequence of the antiluciferase antisense
PNA is shown along with the biotin (bio) moiety at the amino terminus
and the tyrosine (Y) and lysine (K) moiety at the carboxy terminus.
There are five linkers (O) at both the near carboxy and near amino
termini. The sequence of luciferase mRNA around the methionine
initiation codon (ATG) is shown. The luciferase (Luc) ORF (orf) was
subcloned into a eukaryotic expression plasmid, designated clone 790,
which was described previously (12). The hygromycin selection gene, the
SV40 promoter, the SV40 3′ UTR, and the Epstein–Barr nuclear antigen
(EBNA)-1 gene are shown. The SV40 3′ UTR contains 200 nucleotides from
the bovine (b) GLUT1 glucose transporter mRNA, which optimizes gene
expression through mRNA stabilization (12). (B)
Antisense imaging agent is comprised of the OX26 mAb to the rat TfR,
which is linked to SA, which binds the monobiotinylated PNA
antisense agent. The PNA contains a Tyr and Lys residue at the amidated
carboxy terminus to enable radiolabeling with 125-iodine on the Tyr
residue or with 111-indium on the Lys residue.