Abstract 912: uPA as a topoisomerase-1 protective agent in lung fibroblast cells

Abstract

Abstract Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer-related death in the United States, with approximately 53,000 people in the U.S. diagnosed with the disease every year. The Gondi lab has previously shown that poor survival rates in pancreatic cancer are correlated with increased expression of urokinase plasminogen activator (uPA), a serine protease. Our previous data has shown for the first time that uPA binds to topoisomerase-1 (TOPO-1), in addition to the interaction of uPA with various transcription factors. Our current research is aimed at elucidating the mechanism of the interaction between uPA and TOPO-1, with the goal of demonstrating a protective role for uPA in the regulation of TOPO-1 function in the presence of TOPO-1 inhibitors. Methods: Two knock-out lung fibroblast cell lines were used. One cell line was a uPA knock-out line, while the other was a uPA knock-out line with a uPA expression vector transfected into the cells. Transfection was performed using Chariot transfection vector. The cell lines were treated with topoisomerase inhibitors TX1111 and SN38. DNA replication activity was measured using flow cytometry as a surrogate for TOPO-1 activity. Controls included untreated cells, cells treated with empty Chariot, and cells treated with Chariot containing TXC peptide. Results and Discussion: In the presence of topoisomerase inhibitors TX1111 and SN38, uPA knock-out lines demonstrated incomplete cell division relative to controls. In uPA-expressing lines, cell division activity was retained in the presence of topoisomerase inhibitors. Our data demonstrates for the first time that uPA serves a protective role in preventing the inhibition of TOPO-1 by topoisomerase inhibitors. This indicates uPA as a potential new drug target in the treatment of chemoresistant pancreatic cancer. Further studies to be performed include visualizing the degree of DNA-replication using DNA combing, and subsequently expanding this study to pancreatic cancer cells. Citation Format: Liang Ge, Manu Gnanamony, Victoria Stepanova, Dzung H. Dinh, Christopher S. Gondi. uPA as a topoisomerase-1 protective agent in lung fibroblast cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 912.