Tumor-targeting peptide-PNA-peptide chimeras for imaging overexpressed oncogene mRNAs.

We have optimized a method involving continuous solid phase synthesis of chelator-peptide-PNA-peptide probes in order to noninvasively image oncogene mRNAs overexpressed in tumors. The PNA (peptide nucleic acid) probes carry cyclized peptide ligand analogs specific for receptors overexpressed on malignant breast or colorectal cancer cells, and chelators to bind radioactive metal ions, or a fluorophore. In vivo scintigraphic imaging of MCF7 xenografts in immunocompromised mice indicated that CCND1 and MYC [99sTc] chelator-PNA-D (CSKC) probes concentrated in MCF7 cells up to 7 times more than the corresponding mismatch controls.