A clinically relevant model of human pancreatic adenocarcinoma identifies patterns of metastasis associated with alterations of the TGF-beta/Smad4 signaling pathway

Genetic alterations impacting the TGF-β/Smad4 pathway are found in nearly all pancreatic adenocarcinomas, and recent reports have identified a relationship between DPC4/Smad4 expression and patient survival. In this study we use a clinically relevant animal model of pancreatic cancer to examine the impact of these genetic changes on the biology of pancreatic cancer. Methods: Using high-density oligonucleotide DNA microarray technology, a comprehensive examination of the components of the TGF-β/Smad4 pathway was performed on three human pancreatic adenocarcinoma cell lines. The in vitro and in vivo growth characteristics of these cell lines was then compared. Finally, using a clinically relevant orthotopic xenograft model of pancreatic cancer, primary tumor growth and metastases were measured for pancreatic tumors derived from each cell line. Results: Examination of the TGF-β/Smad4 pathway components identified that these three cell lines possess molecular profiles consistent with ∼90% of pancreatic adenocarcinoma tumors in patients. A significant discrepancy between in vitro and in vivo growth characteristics of each cell line was identified. When tumors from each cell line were established in nu/nu mice, each cell line exhibited distinct metastatic profiles. Data from these studies is consistent, with clinical observations concerning DPC4/Smad4 and patient outcome. Conclusion: Using an orthotopic model of tumor growth and metastasis identifies distinct metastatic profiles associated with molecular alterations of the TGF-β/Smad4 pathway and provides insight with regard to the biologic consequences of these changes.