IJCEM Copyright © 2008-All rights reserved. Published by e-Century Publishing Corporation, Madison, WI 53711
Int J Clin Exp Med 2010;3(1):84-87

Medical Hypothesis
No small matter: microRNAs -- key regulators of cancer stem cells

Qing Ji, David Karnak, Ping Hao, Rongquan Wang, Liang Xu

Department of Digestive Diseases, The First Affiliated Hospital, Department of Oncology, The Second Affiliated Hospital, Third Military
Medical University, Chongqing 400038, China; Department of Radiation Oncology, Comprehensive Cancer Center, University of
Michigan, Ann Arbor, MI 48109, USA

Received February 5, 2010, accepted March 5, 2010, available online March 12, 2010

Abstract: Emerging evidence demonstrates that both tumor suppressor and oncogenic miRNAs play an essential role in stem cell
self-renewal and differentiation by negatively regulating the expression of certain key genes in stem cells. It seems logical that they may
also be critical players in cancer stem cells.  Though small in size, miRNAs play a key role in the epigenetic regulation of cancer stem
cells.  Specifically, the imbalance of oncogenic vs. tumor suppressor miRNAs may lead to dysregulation of cancer stem cells, thus
causing excessive self-renewal and survival of cancer stem cells, and resistance to chemo/radiotherapy.  We postulate that restoring
the balance of miRNAs will correct this dysregulation via the direct and simultaneous modulation of downstream stem cell pathways
involved in cancer stem cell self-renewal and/or differentiation.  The resultant restoration of key regulatory pathways could improve
therapeutic response.  Restoring tumor suppressor miRNAs and/or inhibiting oncogenic miRNAs may provide a novel molecular
therapy for human cancers, potentially via modulating cancer stem cells. (IJCEM1002003).

Key words: microRNAs, stem cells, cancer, regulators, oncogene

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Address all correspondence to:
Qing Ji, M.D., Ph.D.
Department of Digestive Diseases
The First Affiliated Hospital
Third Military Medical University
Chongqing 400038
Tel: 86-13500380255

Liang Xu, M.D., Ph.D.
Department of Radiation Oncology
Division of Cancer Biology
University of Michigan
4424E Med Sci I
1301 Catherine St.
Ann Arbor, MI 48109-5637
Tel: 734-615-7017
Fax: 734-615-3422