Mouse modeling of pancreatic ductal adenocarcinoma (PDAC) search for early diagnostic markers and therapeutic targets.

摘要

PDAC is a highly malignant neoplasm that carries a very poor prognosis. PDAC development is a multistage transformation process that involves multiple genetic alterations that include activation of EGFR/HER2 and KRAS, and loss-of-function mutations in INK4A/ARF, p53 and SMAD4. In recent years, several genetically engineered mouse models that accurately recapitulate human pancreatic neoplasia have been developed. Histological characterizations of those models have revealed possible roles for the mutated RAS, INK4a/ARF and p53 in pancreatic tumorigenesis. However, the role of SMAD4 mutation, which is associated with late stages of tumor progression, has yet to be explored. Additionally, those models that would be useful in studying biological processes of PDAC are currently underutilized.In this study, we first aimed to determine the role of Smad4 mutation in pancreatic tumor development by characterizing an animal model. The model developed here harbored loss of Smad4 in the context of KrasG12D in tissue specific manner. Histopathological examination of 16 animals illustrated that the inactivation of Smad4 accelerated KrasG12D-mediated pancreatic neoplasia, with infrequent evidence of metastasis. This rapid disease progression was solely due to the loss of Smad4 and not to other PDAC-related mutations. One unique characteristics of this model was the frequent development of IPMN, a rarer type of benign pancreatic tumor in human patients. Interestingly, the loss of Smad4 without KrasG12D led to a normal development of the pancreas, suggesting that Smad4 is dispensable for pancreatic organogenesis.In the second aim of this dissertation, we sought to utilize serum and tissue from known murine models of pancreatic cancer, in addition to human patient samples, to determine disease-related protein biomarkers that could be used in early diagnosis and effective therapy of PDAC. In order to effectively analyze the proteome of serum and tissue specimens from mouse and/or human, we developed a HTP multi-dimensional fractionation method for serum, and FFPE tissue proteomic analysis method for tissues as a part of this dissertation. With a use of the "state-of-the-art" mass spectrometry and newly developed methods, disease-related proteome was revealed in depth at the whole array of disease stages from early to late PanIN to full-blown PDAC.Keywords: pancreas, cancer, mouse, Smad4, proteomics, biomarker.