Evaluation of neurotensin receptor 1 as a potential imaging target in pancreatic ductal adenocarcinoma.

Pancreatic cancer is one of the deadliest human malignancies and lack of effective diagnostic and therapeutic methods. Accumulating evidence suggests that the neurotensin (NT) and neurotensin receptors (NTRs) play key roles in pancreatic adenocarcinoma growth and survival. In this study, we not only evaluate the NTR1 expression in pancreatic cancer patient samples, but also explore the PET and fluorescence imaging of NTR1 expression in pancreatic cancer animal models. The NTR1 expression was evaluated by immunohistochemistry staining in clinical patient tissue samples with pancreatic ductal adenocarcinoma, insulinoma, and pancreatitis. The results showed 79.4% positive rate of NRT1 expression in pancreatic ductal adenocarcinoma, compared with 33.3 and 22.7% in insulinoma and pancreatitis samples, respectively. High NTR1 gene expression was also found in Panc-1 cells and confirmed by cell immunofluorescence. Cu-AmBaSar-NT and IRDye800-NT were synthesized as imaging probes and maintained the majority of NTR1-binding affinity. In vivo imaging demonstrated that Cu-AmBaSar-NT has prominent tumor uptake (3.76 ± 1.45 and 2.29 ± 0.10%ID/g at 1 and 4 h post-injection). NIR fluorescent imaging with IRDye800-NT demonstrated good tumor-to-background contrast (8.09 ± 0.38 × 10 and 6.67 ± 0.43 × 10 (p/s/cm/sr)/(μW/cm) at 30 and 60 min post-injection). Fluorescence guided surgery was also performed as a proof of principle experiment. In summary, our results indicated that NTR1 is a promising target for pancreatic ductal adenocarcinoma imaging and therapy. The imaging probes reported here may not only be considered for improved diagnosis of pancreatic ductal adenocarcinoma, but also has the potential to be fully integrated into patient screening and treatment monitoring of future NTR1 targeted therapies.