Abstract 2204: A functional genomics approach using high-throughput RNAi identifies TNK1 as a putative oncogene in pancreatic cancer
Authors: Meredith C. Henderson, Shilpi Arora, Irma M. Gonzales, Ashish Choudhary, Jeffrey A. Kiefer, Jeffrey M. Trent, Daniel D. Von Hoff, Spyro Mousses, David O. Azorsa
Journal: Cancer Research (2010)

Abstract Pancreatic cancer is a deadly disease that kills more than 30,000 people in the United States each year. Pancreatic cancer often presents as an advanced, therapy resistant cancer that is refractory to many forms of chemotherapy. Current therapeutics to treat pancreatic cancer include gemcitabine, yet the one-year survival of pancreatic cancer patients treated with gemcitabine is about 18%, representing a significant but modest advancement in the quality of life. In order to improve gemcitabine response in pancreatic cancer cells, we utilized high-throughput RNAi (HT-RNAi) to identify genes that when silenced would sensitize pancreatic cancer cells to gemcitabine. This screen also identified genes that represent “Achilles Heel” targets, which when silenced, results in a decrease in pancreatic cancer cell viability. A HT-RNAi assay was developed to monitor the growth inhibition of BxPC3 pancreatic cancer cells transfected with siRNA and treated with gemcitabine. For screening, BxPC3 cells were transfected with siRNA from several two siRNA libraries including kinases (574 kinases) and druggable-genome targets (∼7000 genes). Twenty-four hours after siRNA transfection, an EC30 dose of gemcitabine was added and growth was assessed after 72 hours of drug exposure. Results from the screen showed that silencing the TNK1 resulted in a significant decrease in cell viability and also modestly increased sensitivity to gemcitabine. These results were consistent with previous HT-RNAi screens performed on MIA PaCa-2 cells. To confirm TNK1 as a potential target, a panel of pancreatic cancer cells were transfected with one of four different TNK1 siRNA and then treated with a range of gemcitabine doses to evaluate gemcitabine sensitivity following knockdown of TNK1. The TNK1 protein has previously been identified as a putative inhibitor of Ras and an inhibitor of TNFα-induced translocation of NFkB. We were able to confirm this in pancreatic cancer cells by demonstrating an increase in p-MEK 1/2 as well as an increase in NFkB gene targets in TNK1 siRNA-treated cells. Furthermore, we have characterized TNK1 expression in a panel of pancreatic cell lines. Although previous studies suggest that TNK1 may serve as a tumor suppressor, here, we suggest that TNK1 also demonstrates oncogenic properties in pancreatic cancer cells. The role that TNK1 plays in pathways such as K-ras and NFkB indicate it is likely to be an important factor in the development and/or progression of pancreatic cancer. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2204.