Abstract LB-353: Targeting pancreatic cancer stem cells by epigenetic regulation of miR-34a

Abstract

Abstract MicroRNA-34a (miR-34a) is a transcriptional target of p53 that is down-regulated in pancreatic cancer. This study aimed to investigate the functional significance of miR-34a on growth of pancreatic cancer stem cells through its epigenetic restoration by chromatin modulators, demethylating agent 5-Aza-2′-deoxycytidine (5-Aza dC) and HDAC inhibitor Suberoylanilide hydroxamic acid (Zolinza/vorinostat/SAHA). Re-expression of miR-34a in pancreatic cancer stem cells and pancreatic cancer cell lines on treatment with 5-Aza dC and SAHA strongly inhibited the cell proliferation, cell cycle progression, self renewal, epithelial to mesenchymal transition and invasion. miR-34a upregulation of by 5-Aza dC and SAHA in pancreatic cancer stem cells (PCSC's) also induced apoptosis by activating caspase 3/7. Modulation of miR-34a expression inhibited the protein expression of its putative target genes Bcl-2, CDK6, Cdc25, SIRT1, which was rescued by inhibiting miRNA-34a in the presence of miR-34a antagomir. miR-34a upregulation also induced acetylated p53, p21WAF1, p27, and PUMA protein levels in PCSC's. Interestingly treatment of PCSC'c with 5-Aza dC and SAHA resulted in the inhibition of epithelial -mesenchymal transition by downregulating N-Cadherin, Zeb-1, a crucial inducer of EMT, Slug and Snail expression and also by transcriptional upregulation of E-Cadherin. SAHA retards in vitro cancer stem cell migration and invasion by the inhibition of Notch signaling pathway. Inhibition of miR-34a by antogomiR abrogates the effects of SAHA and 5-Aza dC, suggesting that SAHA and 5-Aza dC regulate stem cell characteristics in PCSC's through miR-34a. The present study thus demonstrates the role of miR-34a as a critical regulator of pancreatic cancer progression. The restoration of miR-34a expression by 5-Aza dC and SAHA in human primary pancreatic cancer stem cells and cell lines will not only provide mechanistic insight and therapeutic targets for pancreatic cancer but also promising reagent to boost patient response to existing chemotherapies or as standalone cancer drug by the elimination of the cancer stem cells characteristics. 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 LB-353. doi:10.1158/1538-7445.AM2011-LB-353