Abstract 2568: Mutant p53 regulates HSP70 expression and nuclear localization

Pancreatic cancer is the 3rd leading cause of cancer related deaths in the US with a median survival of less than one year. No effective therapies or early detection tests are available for these patients. Scientists have been studying cellular origins of pancreatic cancer to aid in the development of novel treatments and biomarkers. Several studies have demonstrated that acinar cells have a high propensity to undergo acinar to ductal metaplasia and form precursor lesions of pancreatic ductal adenocarcinoma. We have recently shown that simultaneous expression of Kras and mutant TP53 can generate invasive ductal adenocarcinoma from ductal cells. We hypothesized specific mutations in TP53 have different mechanisms of transforming ductal cells. In order to understand the role of mutant TP53 in transforming pancreatic ductal cells into invasive ductal adenocarcinoma, we used a lentiviral system to express mutant TP53R175H and TP53R273H, two of the most frequently mutated TP53 alleles in pancreatic cancer patients, in immortalized pancreatic ductal epithelial cells carrying a Kras mutation (HPNE-KrasG12D). Trypan blue dye exclusion assay and Spheroid formation assays were used to study cellular proliferation and cancer stem cell (CSC) populations. Mutant TP53 over expression enhanced CSC populations without altering cellular proliferation in HPNE-KrasG12D cells. Reverse phase protein array (RPPA) was carried out to detect gene expression changes in HPNE-KrasG12D cells upon mutant TP53 over expression. RPPA assay results suggested that TP53R175H uniquely induced HSP70 expression in HPNE-KrasG12D cells, as cells expressing either vector control or TP53R273H failed to do so. HSP70 expression was further validated by transiently overexpressing TP53R175H and TP53R273H. Surprisingly, TP53R175H specifically promoted nuclear localization of HSP70 without altering the expression of a recently identified HSP70 nuclear transporter, Hikeshi. Future studies will determine 1) whether HSP70 is required for p53-mediated stemness in HPNE-KrasG12D cells and 2) the function of nuclear HSP70. In summary, over expression of mutant p53 enhanced cancer stem cell properties of HPNE-KrasG12D cells, through upregulation HSP70. The exact mechanism behind HSP70 nuclear localization and increased cancer stem cell properties is being more rigorously explored. Citation Format: Kishore Polireddy, Kanchan Singh, Melissa Pruski, Wasim Dar, John S. Bynon, Jennifer M. Bailey. Mutant p53 regulates