Rationale: The ?v?6- and ?v?8-integrins, two cell-adhesion receptors upregulated in many tumors and involved in the activation of the latency associated peptide (LAP)/TGF? complex, represent potential targets for tumor imaging and therapy. We investigated the tumor-homing properties of a chromogranin A-derived peptide containing an RGDL motif followed by a chemically stapled alpha-helix (called "5a"), which selectively recognizes the LAP/TGF? complex-binding site of ?v?6 and ?v?8. Methods: Peptide 5a was labeled with IRDye 800CW (a near-infrared fluorescent dye) or with 18F-NOTA (a label for positron emission tomography (PET)); the integrin-binding properties of free peptide and conjugates were then investigated using purified ?v?6/?v?8 integrins and various ?v?6/?v?8 single - or double-positive cancer cells; tumor-homing, biodistribution and imaging properties of the conjugates were investigated in subcutaneous and orthotopic ?v?6-positive carcinomas of the pancreas, and in mice bearing subcutaneous ?v?8-positive prostate tumors. Results: In vitro studies showed that 5a can bind both integrins with high affinity and inhibits cell-mediated TGF? activation. The 5a-IRDye and 5a-NOTA conjugates could bind purified ?v?6/?v?8 integrins with no loss of affinity compared to free peptide, and selectively recognized various ?v?6/?v?8 single- or double-positive cancer cells, including cells from pancreatic carcinoma, melanoma, oral mucosa, bladder and prostate cancer. In vivo static and dynamic optical near-infrared and PET/CT imaging and biodistribution studies, performed in mice with subcutaneous and orthotopic ?v?6-positive carcinomas of the pancreas, showed high target-specific uptake of fluorescence- and radio-labeled peptide by tumors and low non-specific uptake in other organs and tissues, except for excretory organs. Significant target-specific uptake of fluorescence-labeled peptide was also observed in mice bearing ?v?8-positive prostate tumors. Conclusions: The results indicate that 5a can home to ?v?6- and/or ?v?8-positive tumors, suggesting that this peptide can be exploited as a ligand for delivering imaging or anticancer agents to ?v?6/?v?8 single- or double-positive tumors, or as a tumor-homing inhibitor of these TGF? activators.
A stapled chromogranin A-derived peptide homes in on tumors that express ?v?6 or ?v?8 integrins
Gori A;Valtorta S;Moresco RM;
2023
Abstract
Rationale: The ?v?6- and ?v?8-integrins, two cell-adhesion receptors upregulated in many tumors and involved in the activation of the latency associated peptide (LAP)/TGF? complex, represent potential targets for tumor imaging and therapy. We investigated the tumor-homing properties of a chromogranin A-derived peptide containing an RGDL motif followed by a chemically stapled alpha-helix (called "5a"), which selectively recognizes the LAP/TGF? complex-binding site of ?v?6 and ?v?8. Methods: Peptide 5a was labeled with IRDye 800CW (a near-infrared fluorescent dye) or with 18F-NOTA (a label for positron emission tomography (PET)); the integrin-binding properties of free peptide and conjugates were then investigated using purified ?v?6/?v?8 integrins and various ?v?6/?v?8 single - or double-positive cancer cells; tumor-homing, biodistribution and imaging properties of the conjugates were investigated in subcutaneous and orthotopic ?v?6-positive carcinomas of the pancreas, and in mice bearing subcutaneous ?v?8-positive prostate tumors. Results: In vitro studies showed that 5a can bind both integrins with high affinity and inhibits cell-mediated TGF? activation. The 5a-IRDye and 5a-NOTA conjugates could bind purified ?v?6/?v?8 integrins with no loss of affinity compared to free peptide, and selectively recognized various ?v?6/?v?8 single- or double-positive cancer cells, including cells from pancreatic carcinoma, melanoma, oral mucosa, bladder and prostate cancer. In vivo static and dynamic optical near-infrared and PET/CT imaging and biodistribution studies, performed in mice with subcutaneous and orthotopic ?v?6-positive carcinomas of the pancreas, showed high target-specific uptake of fluorescence- and radio-labeled peptide by tumors and low non-specific uptake in other organs and tissues, except for excretory organs. Significant target-specific uptake of fluorescence-labeled peptide was also observed in mice bearing ?v?8-positive prostate tumors. Conclusions: The results indicate that 5a can home to ?v?6- and/or ?v?8-positive tumors, suggesting that this peptide can be exploited as a ligand for delivering imaging or anticancer agents to ?v?6/?v?8 single- or double-positive tumors, or as a tumor-homing inhibitor of these TGF? activators.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
