Integrin α6-Targeted Positron Emission Tomography Imaging of Colorectal Cancer

Colorectal cancer (CRC) is the third most common cancer and the fourth leading cause of cancer deaths worldwide. Integrin α6 is overexpressed in all stages of CRC which makes it a potential diagnostic biomarker for CRC. Previously, we identified an integrin α6-targeted peptide CRWYDENAC (dubbed RWY) using phage display technology and employed it for nasopharyngeal carcinoma specific nanotherapeutics. In this study, we developed a radiotracer, ¹⁸F-RWY, based on this integrin α6-targeted RWY peptide for positron emission tomography (PET) imaging of CRC. Integrin α6 was overexpressed on several CRC cells including HT29 cells where the biotin-labeled RWY peptide colocalized with integrin α6. ¹⁸F-RWY PET imaging was performed on subcutaneous, chemically induced, and genetically engineered CRC mice. ¹⁸F-RWY generated high PET signals in subcutaneous HT29 tumors, and the tumor uptake of ¹⁸F-RWY was reduced by a blocking study using nonradio-labeled RWY. Moreover, ¹⁸F-RWY PET imaging enabled detection of CRC in chemically induced and genetically engineered CRC mice. The overexpression of integrin α6 in tumor tissues isolated from chemically induced and genetically engineered CRC mice was confirmed. These results demonstrate the potential clinical application of ¹⁸F-RWY for PET imaging of CRC.