Preparation of radio-iodine labeled PKC{delta}-V5 heptapeptide and its application of tumor imaging in lung cancer cell bearing nude mouse

1126 Objectives PKCδ-catalytic V5 Heptapeptide (FEQFLDI, FP7) interacts with heat shock protein 27 (HSP27) and inhibits HSP27-mediated resistance to cell death against various stimuli including radiation and cisplatin. Here, we further investigated uptake properties of radio-iodinated FP7 in cells and in vivo imaging to evaluate FP7 as a tracer for targeting HSP27 protein. Methods Peptide sequence of FP7 was modified by substituting its C-terminus residues to tyrosine (FP6Y) to label radio-iodine. Accumulation of [125I]iodo-FP6Y in NCI-H1299 cell line, with higher level of HSP27, and NCI-H460 cell line, with lower level of HSP27, was measured by gamma scintillation counter. For in vivo imaging study, the gamma camera images of mice were scanned after injection of [123I]iodo-FP6Y to NCI-H1299 tumor cell bearing nude mice. Results The modification of substituting C-terminus residue of FP7 to tyrosine (FP6Y) did not affect its interaction with HSP27. The radio-labeling yields of [125I]iodo-FP6Y and [123I]iodo-FP6Y were 97.4% to 68.4%, respectively. Accumulation of [125I]iodo-FP6Y in NCI-H1299 cells was 3 fold higher than in NCI-H460 cells. In scintigraphic planar image, [123I]iodo-FP6Y showed retained tumor uptake in NCI-H1299 bearing nude mice. Conclusions The novel radioiodinated FP6Y would be a candidate for HSP27 overexpressed tumor imaging