Abstract

Purpose Imaging of glioblastoma multiform (GBM) tumor using (68)-Galium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaceticacid-Ser-Ser-Ser-Leu-Thr-Val-Ser-Pro-Trp-Tyr (Ga-68-DOTA-(Ser)3-LTVSPWY) as a PET radiotracer for HER2 receptor due to fact that this receptor plays a pivotal role in the tumorigenesis and tumor progression in a wide range of cancer. Methods Ga-68-DOTA-(Ser)(3)-LTVSPWY was produced with high radiochemical purity. The affinity and specificity of this radiotracer toward HER2 receptor on the surface of glioma glioblastoma (U-87 MG) cell line were evaluated. Furthermore, the biodistribution and PET imaging of this radiolabeled peptide were investigated on xenografted U-87 MG tumor-bearing mice. Results The in-vitro specific binding study revealed that the Ga-68-DOTA-(Ser)(3)-LTVSPWY binds to different cell lines with respect to their level of HER2 expression. The calculated K-D and B-max of radiolabeled peptide toward U-87 MG cell line were 5.5 +/- 2.4 nmol/l and (2.4 +/- 0.3) x 10(5) receptors per cell, respectively. The highest tumor uptake was observed at 30-min postinjection, whereas the tumor-to-muscle ratio was about four-fold. The acquired PET images distinctively show tumor site, which was blocked with excess nonlabeled peptide that revealed specific in-vivo targeting of Ga-68-DOTA-(Ser)(3)-LTVSPWY for glioma. Conclusion Ga-68-DOTA-(Ser)(3)-LTVSPWY specifically recognizes HER2 receptors and could be a potential candidate for GBM imaging.