EFFECT OF MUTANT P53 ON METASTATIC POTENTIAL IN PANCREATIC DUCTAL ADENOCARCINOMA

Pancreatic ductal adenocarcinoma (PDAC) is the most common type of pancreatic cancer, with an incredibly low 5-year survival rate of only 7.7%. One of the reasons that PDAC is so deadly is due to how difficult it is to diagnose until it has metastasized to distant vital organs. Thus, identifying a gene linked to metastasis and testing its effect on the progression of PDAC is crucial. It has previously been demonstrated that the tumor suppressor gene p53 promotes metastasis in breast cancer. Mutations in the gene have been found in PDAC and most of these mutations occur at the R273 codon in humans (R270 in mice). This project aimed to test the hypothesis that the p53^R270H mutation in mice results in increased metastatic potential of the pancreatic cancer cells. The mouse used for this work was the KCip53 mouse, in which the permanent expression of mutant KrasG12D (known to initiate the precursor lesions that lead to PDAC) is driven by the Cre-lox system, and the expression of mutant p53^R270H is driven by the addition, or lack of, doxycycline, and is therefore inducible and reversible. To test metastatic potential, we first performed a series of scratch assays using KCip53 cells isolated from the pancreatic tumors of KCip53 mice, which demonstrated that pancreatic cancer cells expressing mutant p53^R270H have an increased rate of scratch closure, and therefore greater invasive and metastatic potential. Furthermore, invasion assays, which test cells’ ability to invade collagen, revealed that pancreatic cancer cells expressing mutant p53^R270H demonstrate increased invasive characteristics. To explore the changes in gene expression that occur when mutant p53^R270H is expressed, we also performed qPCR assays with KCip53 subcutaneous tumors. These qPCR assays revealed increased expression of mesenchymal markers (a sign of epithelial to mesenchymal transition) and ductal differentiation markers, and a decrease in expression of WT p53 targets, all of which support mutant p53^R270H as a driver of pancreatic cancer progression and metastasis. Overall, this project has shown that the expression of mutant p53^R270H results in increased metastatic potential in pancreatic ductal adenocarcinoma. This finding could serve as a useful therapeutic tool for patients suffering from PDAC that has metastasized, for which there is currently limited treatment, by targeting mutations in the R273 p53 codon in humans.