title: Targeting epigenetic regulation of miR-34a for treatment of pancreatic cancer by inhibition of pancreatic cancer stem cells.
abstract: BACKGROUND
  MicroRNA-34a (miR-34a) is a transcriptional target of p53 and is down-regulated in pancreatic cancer. This study aimed to investigate the functional significance of miR-34a in pancreatic cancer progression through its epigenetic restoration with chromatin modulators, demethylating agent 5-Aza-2'-deoxycytidine (5-Aza-dC) and HDAC inhibitor Vorinostat (SAHA).
  
  
  RESULTS
  Re-expression of miR-34a in human pancreatic cancer stem cells (CSCs) and in human pancreatic cancer cell lines upon treatment with 5-Aza-dC and SAHA strongly inhibited the cell proliferation, cell cycle progression, self-renewal, epithelial to mesenchymal transition (EMT) and invasion. In pancreatic CSCs, modulation of miR-34a induced apoptosis by activating caspase-3/7. Treatment of pancreatic CSCs with the chromatin-modulating agents resulted in the inhibition of Bcl-2, CDK6 and SIRT1, which are the putative targets of miR-34a. MiR-34a upregulation by these agents also induced acetylated p53, p21(WAF1), p27(KIP1) and PUMA in pancreatic CSCs. Inhibition of miR-34a by antagomiR abrogates the effects of 5-Aza-dC and SAHA, suggesting that 5-Aza-dC and SAHA regulate stem cell characteristics through miR-34a. In CSCs, SAHA inhibited Notch pathway, suggesting its suppression may contribute to inhibition of the self-renewal capacity and induction of apoptosis. Interestingly, treatment of pancreatic CSCs with SAHA resulted in the inhibition of EMT with the transcriptional up-regulation of E-Cadherin and down-regulation of N-Cadherin. Expression of EMT inducers (Zeb-1, Snail and Slug) was inhibited in CSCs upon treatment with SAHA. 5-Aza-dC and SAHA also retard in vitro migration and invasion of CSCs.
  
  
  CONCLUSIONS
  The present study thus demonstrates the role of miR-34a as a critical regulator of pancreatic cancer progression by the regulating CSC characteristics. The restoration of its expression by 5-Aza-dC and SAHA in CSCs will not only provide mechanistic insight and therapeutic targets for pancreatic cancer but also promising reagents to boost patient response to existing chemotherapies or as a standalone cancer drug by eliminating the CSC characteristics.
authors: Departments of Pathology and Laboratory Medicine, The University of Kansas Medical Center, Kansas City, Kansas, United States of America.
authors: Dara
authors: D
authors: Nalls
authors: Su-Ni
authors: SN
authors: Tang
authors: Marianna
authors: M
authors: Rodova
authors: Rakesh K
authors: RK
authors: Srivastava
authors: Sharmila
authors: S
authors: Shankar
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D001374:Azacitidine / Q000494:pharmacology / Q000627:therapeutic use; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002843:Chromatin / Q000378:metabolism; D044127:Epigenesis, Genetic / Q000187:drug effects; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology / Q000627:therapeutic use; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D009361:Neoplasm Invasiveness; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D010190:Pancreatic Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology; D018874:Spheroids, Cellular / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D014410:Tumor Stem Cell Assay; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D000077337:Vorinostat
chemical_list: D002843:Chromatin; D006877:Hydroxamic Acids; C522425:MIRN34 microRNA, human; D035683:MicroRNAs; D000077337:Vorinostat; D001374:Azacitidine