An orthotopic model of ductal adenocarcinoma of the pancreas in severe combined immunodeficient mice representing all steps of the metastatic cascade

Introduction: Clinically relevant animal models are needed to evaluate new therapeutic strategies against pancreatic adenocarcinoma, which is almost incurable by established treatment. Aims: To establish and characterize a metastatic orthotopic transplant model for pancreatic ductal adenocarcinoma in severe combined immunodeficient (SCID) mice. Methodology: Human pancreatic ductal carcinoma cells, PancTu 1, were implanted either subcutaneously or orthotopically into the pancreas. Results: After 4 weeks, orthotopic transplantation resulted in an extensive local tumor growth of an undifferentiated ductal adenocarcinoma with slight to moderate desmoplastic reaction. The tumor growth and spread resembled the situation in humans, including invasion into adjacent organs causing biliary and stomach obstruction. In addition, tumor metastases to regional lymph nodes of the pancreas, lung, liver, mesentery, and diaphragm, and attached to the kidneys, spleen, and reproductive organs were observed. In contrast, no invasion or metastases could be demonstrated by subcutaneous implanted PancTu 1 cells. Using immunohistochemical analysis, even single human tumor cells could be detected in blood vessels and metastatic organs, providing evidence that the orthotopic transplant model appropriately reflects the entire process of the metastatic cascade. Conclusion: This cancer model in SCID mice appears to be a powerful tool to investigate the identity of metastasis-associated genes and to evaluate preclinically the potency of novel antimetastatic agents in ductal adenocarcinoma of the pancreas.