Pancreatic ductal adenocarcinoma: cellular origin, signaling pathways and stroma contribution.

Pancreatic cancer has a very poor prognosis, in part due to its diagnosis at late stages of the disease and to limited response to chemotherapy and radiotherapy. The vast majority of pancreatic cancers are classified as pancreatic ductal adenocarcinomas (PDACs). Despite advances in knowledge on the cellular origin of PDAC or the involvement of signal transduction pathways therein, many questions remain unanswered. In this review, we summarize recent findings and current hypotheses regarding these two questions. Since pancreatitis is a risk factor for human PDAC, and the latter proceeds with an intense fibrotic reaction, we also analyze the role of the stroma in PDAC progression. An improved understanding of these key aspects for PDAC ontogeny will open new avenues for tumor prevention, early detection, and improved therapy.