Abstract 2584: eNOS as a therapeutic target in pancreatic cancer

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Pancreatic cancer has a very high mortality rate, and frontline therapy has not changed in over a decade indicating a need for novel therapeutics. In this regard, endothelial Nitric Oxide Synthase (eNOS) has emerged as a new target due to recent studies demonstrating elevated expression in human pancreatic cancers, and inhibition of pancreatic tumor growth with eNOS knockdown or knockout in xenograft and genetically engineered mouse models. By pharmacologically testing eNOS inhibition, we found that a non-selective NOS inhibitor, L-NG-Nitroarginine methyl ester (L-NAME), inhibited tumor growth of human pancreatic cancer cell lines and extended survival in the aggressive Pdx-1-CreTg/+;LSL-KRASG12D/+;LSL-Trp5R172H/+ (KPC) mouse model of pancreatic ductal adenocarcinoma (PDAC) by ∼30 days. This extended survival is particularly significant given that the current frontline therapy, gemcitabine, does not provide these mice with a similar survival advantage. While general inhibitors such as L-NAME are attractive molecules to explore, evidence has shown that targeting all three NOS enzymes can have undesirable off-target effects. As eNOS has been identified as the NOS family member required for pancreatic tumorigenesis, and there currently are no selective eNOS inhibitors, we have created and optimized a cell-based system to identify potent and selective compounds for eNOS inhibition. This assay uses a mammalian baculovirus expression system to distinguish the activity of eNOS, nNOS, and iNOS via measurement of the stable bi-products of nitric oxide synthesis, and has been tested with a variety of published NOS inhibitors including L-NAME, the iNOS specific inhibitor 1400W, and the nNOS specific inhibitor L-NPA. The assay is suitable for high throughput screening of small molecule libraries to identify novel eNOS inhibitors that, when paired with gemcitabine, may represent a novel combination therapy for pancreatic cancer therapeutics. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2584. doi:10.1158/1538-7445.AM2011-2584