Abstract 710: Genetic identification of Annexin-A8 as a therapeutic target and prognostic marker for pancreatic cancer

Abstract

Abstract Introduction: We previously have identified histologic grade as an important prognostic factor for outcomes in early stage pancreatic cancer following surgical resection. In this study we investigated genes associated with histologic differentiation in early stage pancreatic cancer and their biologic relevance. Methods: We studied the gene expression profile of 61 resected primary pancreatic cancers through analysis of a custom Affymetrix microarray. Significance analysis of microarrays was used to select genes associated with histologic grade. Following identification of these genes we focused on Annexin A8 (A-A8) for further mechanistic studies. We analyzed the relationship of protein expression, tumor grade and outcomes using immunohistochemistry (IHC) in a tissue microarray (TMA) of 91 resected pancreatic cancer patients. Mechanistic studies of A-Aa8 included gene silencing using SiRNA and measurement of the cellular effects by migration, proliferation and colony formation assays. Statistical analysis was performed with Fisher's exact test, T-test and ANOVA as indicated and Cox modeling was used for survival analysis. Results: We identified 34 genes that were downregulated, and 15 genes that were upregulated as tumor grade progressed from well to moderate to poorly differentiated. Then we focused on A-A8 induction in this data set, with a 5.9 fold increased A-A8 expression from low to high grade tumors (r=0.31;p=0.019), the immunohistochemical expression of A-A8 was correlated with tumor grade in a human pancreatic tumor tissue microarray (r=0.26;p=0.014); finally high expression of A-A8 is associated with a significant decrease in 5 year survival following resection of stage I and II human pancreatic cancer by Cox model (p=0.049). Western blotting confirmed increased expression of A-A8 in human pancreatic cancer cell lines. Knockdown of A-A8 in human pancreatic cancer BXPC-3 cells with SiRNA resulted in significant decrease in cell viability (p<0.001), cell migration (2.5 vs. 0.9mm at 96h;p=0.048), and colony formation (p=0.007). Conclusions: Studying the expression profiles of primary pancreatic cancer analyzed on Affymetrix microarrays, we identified A-A8 as a gene associated with pancreatic cancer differentiation. Downregulation of A-A8 by RNA interference in pancreatic cancer cells results in growth and migration inhibition. Finally we show that high A-A8 expression is associated with poor disease outcome in pancreatic cancer patients. These results support further investigation of Annexin A8 as a potential therapeutic target and prognostic marker for human pancreatic cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 710. doi:1538-7445.AM2012-710