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Vol. 9, No. 3, 2009
Issue release date: May 2009
Section title: Original Paper
Free Access
Pancreatology 2009;9:293–301
(DOI:10.1159/000186051)

Epigenetic Silencing of MicroRNA miR-107 Regulates Cyclin-Dependent Kinase 6 Expression in Pancreatic Cancer

Lee K.-H.a, g · Lotterman C.c, d · Karikari C.a · Omura N.a · Feldmann G.a · Habbe N.a · Goggins M.G.a, b, c · Mendell J.T.e, f · Maitra A.a, c, f
Departments of aPathology, bMedicine, cOncology, dPediatrics, and eMolecular Biology and Genetics, The Sol Goldman Pancreatic Cancer Research Center, and fMcKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Md., USA; gDepartment of Gastroenterology, Sung Kyun Kwan University School of Medicine, Seoul, South Korea
email Corresponding Author

Abstract

Aberrant expression of microRNAs (miRNAs) has emerged as an important hallmark of cancer. However, the putative mechanisms regulating miRNAs per se are only partially known. It is well established that many tumor suppressor genes in human cancers are silenced by chromatin alterations, including promoter methylation and histone deacetylation. We postulated that miRNAs undergo similar epigenetic inactivation in pancreatic cancer. Two human pancreatic cancer cell lines – MiaPACA-2 and PANC-1 – were treated with the demethylating agent, 5-aza-2′-deoxycytidine (5-Aza-dC) or the histone deacetylase inhibitor, trichostatin A, as well as the combination of the two. Expression of miRNAs in control and treated cell lines was assessed using a custom microarray platform. Fourteen miRNAs were upregulated two-fold or greater in each of the cell lines following exposure to both chromatin-modifying agents, including 5 that were in common (miR-107, miR-103, miR-29a, miR-29b, and miR-320) to both MiaPACA-2 and PANC-1. The differential overexpression of miR-107 in the treated cancer cell lines was confirmed by Northern blot assays. Methylation-specific PCR assays for assessment of CpG island methylation status in the 5′ promoter region of the miR-107 primary transcript demonstrated complete loss of methylation upon exposure to 5-Aza-dC. Enforced expression of miR-107 in MiaPACA-2 and PANC-1 cells downregulated in vitro growth, and this was associated with repression of the putative miR-107 target, cyclin-dependent kinase 6, thereby providing a functional basis for the epigenetic inactivation of this miRNA in pancreatic cancer.

© 2009 S. Karger AG, Basel and IAP


  

Key Words

  • microRNA
  • Promoter methylation
  • miR-107

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Author Contacts

Anirban Maitra
CRB II, Room 345
Johns Hopkins University School of Medicine
1550 Orleans St, Baltimore, MD 21231 (USA)
Tel. +1 410 955 3511, Fax +1 410 614 0671, E-Mail amaitra1@jhmi.edu

  

Article Information

Received: September 23, 2008
Accepted after revision: December 4, 2008
Published online: April 29, 2009
Number of Print Pages : 9
Number of Figures : 6, Number of Tables : 2, Number of References : 63

  

Publication Details

Pancreatology

Vol. 9, No. 3, Year 2009 (Cover Date: May 2009)

Journal Editor: Urrutia R. (Rochester, Minn.)
ISSN: 1424-3903 (Print), eISSN: 1424-3911 (Online)

For additional information: http://www.karger.com/PAN


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References

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  37. Calhoun ES, Hucl T, Gallmeier E, West KM, Arking DE, Maitra A, Iacobuzio-Donahue CA, Chakravarti A, Hruban RH, Kern SE: Identifying allelic loss and homozygous deletions in pancreatic cancer without matched normals using high-density single-nucleotide polymorphism arrays. Cancer Res 2006;66:7920–7928.
  38. Sato N, Fukushima N, Maitra A, Matsubayashi H, Yeo CJ, Cameron JL, Hruban RH, Goggins M: Discovery of novel targets for aberrant methylation in pancreatic carcinoma using high-throughput microarrays. Cancer Res 2003;63:3735–3742.
  39. Sato N, Maitra A, Fukushima N, van Heek NT, Matsubayashi H, Iacobuzio-Donahue CA, Rosty C, Goggins M: Frequent hypomethylation of multiple genes overexpressed in pancreatic ductal adenocarcinoma. Cancer Res 2003;63:4158–4166.
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