Targeting Epigenetic Regulation of miR-34a for Treatment of Pancreatic Cancer by Inhibition of Pancreatic Cancer Stem Cells

• Published in: PloS one Vol. 6; no. 8; p. e24099
• Main Authors: Nalls, Dara, Tang, Su-Ni, Rodova, Marianna, Srivastava, Rakesh K., Shankar, Sharmila
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 31.08.2011; Public Library of Science (PLoS)
• Subjects: Apoptosis; Apoptosis - drug effects; Apoptosis - genetics; Azacitidine - pharmacology; Azacitidine - therapeutic use; Azacytidine; Bcl-2 protein; Biology; Biomarkers; Breast cancer; Cancer; Cancer prevention; Cancer therapies; Care and treatment; Caspase; Caspase-3; Cell cycle; Cell Cycle - drug effects; Cell Cycle - genetics; Cell growth; Cell Line, Tumor; Cell Movement - drug effects; Cell proliferation; Cell Proliferation - drug effects; Cell self-renewal; Chemotherapy; Chromatin; Chromatin - metabolism; Cyclin-dependent kinase inhibitor p21; Cyclin-dependent kinase inhibitor p27; Departments; Development and progression; E-cadherin; Epigenesis, Genetic - drug effects; Epigenetic inheritance; Epigenetics; Epithelial-Mesenchymal Transition - drug effects; Epithelial-Mesenchymal Transition - genetics; Gene expression; Gene Expression Regulation, Neoplastic - drug effects; Gene regulation; Histone deacetylase; Humans; Hydroxamic Acids - pharmacology; Hydroxamic Acids - therapeutic use; Inhibition; Laboratories; Leukemia; Medical prognosis; Medicine; Mesenchyme; Metastasis; MicroRNAs - genetics; MicroRNAs - metabolism; miRNA; Modulators; Multiple myeloma; Mutation; N-Cadherin; Neoplasm Invasiveness; Neoplastic Stem Cells - drug effects; Neoplastic Stem Cells - metabolism; Neoplastic Stem Cells - pathology; Notch protein; p53 Protein; Pancreatic cancer; Pancreatic Neoplasms - drug therapy; Pancreatic Neoplasms - genetics; Pancreatic Neoplasms - pathology; Pathology; Pharmacology; Physiology; Prostate cancer; Reagents; Restoration; Ribonucleic acid; RNA; Scholarships & fellowships; SIRT1 protein; Spheroids, Cellular - drug effects; Spheroids, Cellular - metabolism; Spheroids, Cellular - pathology; Stem cells; Toxicology; Transcription; Tumor cell lines; Tumor proteins; Tumor Stem Cell Assay; Tumorigenesis; Up-Regulation - drug effects; Up-Regulation - genetics; United States > US; Kansas City Missouri; Kansas
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0024099

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). 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. 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.