Abstract PR13: The expression landscape of pancreatic cancer recurrence following resection
Authors: Dudgeon Crissy , Rosenfeld Jeffrey , Collisson Eric , Carpizo Darren 
Published: May 2019

Abstract
Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive human malignancies with a 5-year survival rate for all stages of only 6%. While surgery remains the most effective treatment for pancreatic cancer, the majority of patients that undergo resection go on to die of pancreatic cancer recurrence. Pancreatic cancer undergoes early stage metastasis; wherein tumorigenic cells disseminate prior to the formation of invasive PDAC during the PanIN stage. The cellular and molecular mechanisms governing the processes of pancreatic cancer metastasis and recurrence following resection are poorly understood in part because there are no animal models of pancreatic cancer recurrence. To address this, we have adapted the Syngraft model, an orthotopic syngeneic mouse model using a pancreatic tumor cell line (Ink4a.1 luc/mcherry) derived from the genetically engineered conditional model (KrasG12D/+; Ink4aflox/flox) that has been modified with lentiviral vectors expressing mCherry and luciferase. Immunocompetent FVB mice were orthotopically injected with 100 Ink4a.1 cells and primary tumor growth was monitored by luciferase activity using the IVIS Spectrum. Mice underwent distal pancreatectomy with spleenectomy when the primary pancreatic tumor measured ~107 photons/sec/cm2, with a mean time to surgical resection at 19 days. Metastatic recurrence to the liver (65%) was followed using the IVIS Spectrum, with a time to metastatic recurrence of 22 +/- 13 days. After 17 pancreatectomies, we observed the following recurrence patterns: 1) liver only (2/17), 2) liver and peritoneal (9/17), and 3) no recurrence (6/17) with a median follow time of 370 days. To investigate the molecular mechanisms of recurrence, we generated four metastatic cell lines from intrahepatic macrometastases. These metastatic cell lines and the control parental Ink4a.1 cell line were subjected to poly A RNA sequencing. Following data analysis by Tophat and Cufflinks, up and down regulation was determined by a 2-fold change in expression. We identified a total of 45 down regulated and 95 up regulated genes. Furthermore, only 1 gene, Basp1, was found to be down regulated while 6 genes, Add2, Col6a3, Npnt, Ntn1, Selp, and Serpinf1, were up regulated in all four metastatic cell lines. Validation by Western blotting confirmed the upregulation of Netrin1 (Ntn1) as a strong candidate for the regulation of metastasis. Because the recurrence patterns following pancreatectomy recapitulate what is seen in human pancreatic cancer, we conclude the Syngraft model can be successfully adapted to study pancreatic cancer recurrence. Future work in the lab will characterize the function(s) of Netrin1 that contribute to the processes of pancreatic cancer metastasis.
Citation Format: Crissy Dudgeon, Jeffrey Rosenfeld, Eric Collisson, Darren Carpizo. The expression landscape of pancreatic cancer recurrence following resection. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Metastasis; 2015 Nov 30-Dec 3; Austin, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(7 Suppl):Abstract nr PR13.