Abstract 2335: Pancreatic cancer stem cell function is regulated by HNF1A
Authors: Abel Ethan V. , Goto Masashi , Ramanathan Nikita , Kumar Chandan , Begley Lesa , Dziubinski Michele L. , Wang Lidong , Waghray Meghna , Urs Sumithra , Simeone Diane M. 
Published: August 2015

Abstract
Pancreatic ductal adenocarcinoma (PDA) is a hierarchal cancer consisting of tumor-initiating cancer stem cells (CSCs) and transiently proliferating bulk tumor cells. Despite this understanding, the biological properties of CSCs remain incompletely defined, including the role of transcriptional programs like epithelial-mesenchymal transition (EMT). Using flow cytometry in conjunction with epithelial-cell surface marker ESA (EpCAM) and mesenchymal-cell surface marker CD44, we identified three subpopulations of PDA cells derived from primary patient samples: CD44highESAlow, CD44lowESAhigh, and CD44highESAhigh cells, each with different biological characteristics. CD44highESAlow cells exhibited a more mesenchymal phenotype characterized by high expression of vimentin and low expression of E-cadherin. CD44lowESAhigh cells, by contrast, highly epithelial in appearance, expressed high levels of E-cadherin and low levels of vimentin. Finally, CD44highESAhigh cells showed a phenotype intermediate between CD44highESAlow and CD44lowESAhigh cells. In isolation, all subpopulations were able to self-renew, however, only CD44highESAhigh cells could give rise to all three cell subpopulations. Additionally, CD44highESAhigh cells exhibited the highest ability to form tumorspheres, an indicator of CSC-functionality, in vitro, and had a greater ability to form tumors in vivo, suggesting that this subpopulation enriched for CSC functional activity. Using microarray analysis, we identified a set 50 genes, including the CSC marker CD24 and the transcription factor HNF1A, which showed significant up-regulation in CD44highESAhigh cells CSC population compared to either CD44highESAlow or CD44lowESAhigh cells. We hypothesized that these genes might be critical to CSC biology in PDA. Using bioinformatics analysis to identify possible transcriptional regulators of these 50 genes, we identified HNF1A as the factor with most highly overrepresented binding sites in the promoter regions of (17/50 genes), suggesting a possible role in regulating CD44highESAhigh-specific genes and serving as a key biological regulator of the CSC state. Supporting this hypothesis, knockdown of HNF1A decreased expression of a number of the candidate genes, including CD24, in the CD44highESAhigh population. By contrast, ectopic expression of HNF1A resulted in the up-regulation of a similar set of candidate genes, including CD24, and promoted the formation of tumorspheres. These findings shine light on the complexity of PDA tumor cell heterogeneity, suggesting the CSCs exist in a state between EMT and mesenchymal-epithelial transition, and implicates HNF1A as a key regulator of CSC-associated genes and CSC functionality.
Citation Format: Ethan V. Abel, Masashi Goto, Nikita Ramanathan, Chandan Kumar, Lesa Begley, Michele L. Dziubinski, Lidong Wang, Meghna Waghray, Sumithra Urs, Diane M. Simeone. Pancreatic cancer stem cell function is regulated by HNF1A. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2335. doi:10.1158/1538-7445.AM2015-2335