Abstract 4738: The early response protein EGR-1 mediates vitamin E γ-tocotrienol-induced apoptosis in pancreatic cancer cells

Abstract

Abstract Background: Vitamin E tocotrienols are bioactive components of cereal foods such as oats, barley, rice bran, and palm, that have demonstrated anticancer and chemopreventive activities in various types of cancer. Recently we have shown that γ-tocotrienol is the most bioactive tocotrienol against pancreatic cancer both in vitro as well as in vivo. However, the molecular mechanism of action of tocotrienols in pancreatic cancer has not been fully elucidated. In this work, we investigated the early genes associated with Vitamin E γ-tocotrienol induced apoptosis, and therefore identify novel pathways related with its anticancer effects. Methods: Human pancreatic cancer MiaPaca-2 cells were treated with γ-tocotrienol (50 µM) and vehicle (ethanol) for 3 h and were subjected to microarray analysis using costume Affymetrix for the identification of early regulatory genes. Early growth response protein-1 (EGR-1) was one of those early response genes induced by γ-tocotrienol. Then we evaluated the protein expression of EGR-1 by real-time PCR and western-blot in pancreatic cancer cell lines (MiaPaca-2 and Panc-1) after treatment with γ-tocotrienol. Mechanistic studies were conducted trough siRNA knockdown of EGR-1 and the rescue of Vitamin of γ-tocotrienol-induced apoptosis, anti-proliferative effects and signaling pathways. Results: We identified 8 genes that were induced and 8 genes that were suppressed early after treatment with γ-tocotrienol in MiaPaca-2 cells. Then we selected and focused on the EGR-1 for signaling pathway analysis. Induction of protein expression was noticed in both MiaPac-2 cells and Panc-1 (6 fold and 10 fold respectively;p<0.05) after 24 h γ-tocotrienol treatment. γ-tocotrienol-induced apoptosis in MiaPac-2 cells and Panc-1 cells (PARP1 cleavage and Annexin V) was associated with induction of p-JNK, p-C-JUN, and EGR-1. Knockdown of EGR-1 in this two cell lines partially rescued γ-tocotrienol-induced apoptosis. Conclusion: Our data identifies EGR-1 as an early gene which is induced by Vitamin E γ-tocotrienol in pancreatic cancer cells. Activation of the EGR-1 pathway, may constitute a novel potential strategy for inhibiting pancreatic tumor growth. 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 4738. doi:1538-7445.AM2012-4738