Evaluation of laminin peptide fragments labeled with indium‐111 for the potential imaging of malignant tumors

The laminin peptide fragments GYIGSR-NH2 and CDPGYIGSR-NH2 are known to bind to a 67-kDa laminin receptor. This receptors is understood to be expressed at higher than normal levels in malignant tumor cells, particularly those of breast and colon carcinomas. Peptides DTPA-GYIGSR-NH2 (1), DTPA-(GYIGSR-NH2)2 (2), DTPA-CDPGYIGSR-NH2 (3), DTPA-(CDPGYIGSR-NH2)2 (4), and negative control DTPA-GAGAGA-NH2 (5) were prepared by solid-phase peptide synthesis. All five DTPA-conjugated peptides were subsequently radiolabeled with 111In and their tissue distribution evaluated in mice bearing C3H tumors. 111In-3 and 111In-4 showed the highest specific tumor localization. These preliminary data support further study of radiolabeled petide fragments for the potential detection of malignant tumors of the breast and other organs.