Cancer is a multistep process, which requires the accumulation of numerous mutations in genes. The identification of the genes involved in the transformation of normal cells is a first step in the development of new biomarkers and new therapeutic regimens. The development of pancreatic cancer is still a deadly disease. The 5 year survival rate is less than 5% in North America. The number of available model systems of pancreatic cancer has greatly expanded to include both animal and cell culture models amenable to define the role of specific genetic alterations in the development of pancreatic cancer. One of the critical failings of diagnosis is the usual late stage of disease progression when symptoms are first noted. Advances have been made in the identification of the causative mutations that occur within the cancer cell that contributes to the initiation of pancreatic intraepithelial neoplasia (PanIN) leading to ductal adenocarcinoma (PDAC). The use of animal models has been limited to the study of known genes and their interactions. However, one of the main advantages of animal models is their use as a gene discovery tool.
The aim of this pilot project is to establish a system which would facilitate the identification of genes that cooperate in tumor initiation and progression in the development of pancreatic cancer. We have recently imported into our laboratory the Sleeping Beauty transposon system. The sleeping beauty transposon is a transposable mobile element that requires two unlinked genetic loci and has been shown to induce tumorigenesis in the mouse. Making use of a conditional transposase locus we can specifically induce mobilization of the transposable element within the pancreatic lineage. We are hypothesizing that the pancreatic specific induction of Sleeping Beauty (SB) will accelerate the development and progression of pancreatic tumorigenesis in mice. Mice harboring a pancreatic specific oncogenic Kras allele exhibit complete penetrance of developing pancreatic intraepithelial neoplasm (PanINs) which are precursors to PDAC. We are proposing to initiate a sensitized screen to determine if SB transposition within the pancreatic lineage results in a decreased latency and a more rapid progression to PDAC in mice harboring the KrasG12D allele. The transposon and activating mutation will be activated in the pancreatic lineage and the mice aged. Pancreatic tumors that develop will be harvested and analyzed. Pathological analysis will provide the data relating to tumor type and progression. Molecular analysis will encompass the isolation and sequencing of the transposon insertion sites. The genomic loci that cooperate with the KrasG12D will be identified. In addition, we will be identifying loci that can potentially induce PDACs within wildtype mice as well. This Proposal will 1) establish the Sleeping Beauty Transposon System as a valuable tool for the isolation and analysis of cooperating oncogenic loci as well as 2) specifically isolate genes associated with pancreatic cancer.
We will be establishing a screen for novel oncogenes and tumor suppressor genes that specifically cooperate with an oncogene associated with >90% of human pancreatic cancer. We will identify the genetic events that occur within the pancreas that express the activated Kras allele that results in neoplastic transformation. The identification of these genes would provide new biomarkers with which to monitor the development of pancreatic cancer in humans as well as to identify molecular pathways with which to target new therapeutic regimens.