Oncogenic role of microRNAs in brain tumors.pdf

REVIEW Oncogenic role of microRNAs in brain tumors Jesse Chung-sean Pang ? Wai Kei Kwok ? Zhongping Chen ? Ho-Keung Ng Received: 19 February 2009 / Revised: 20 March 2009 / Accepted: 21 March 2009 / Published online: 3 April 2009
Springer-Verlag 2009 Abstract MicroRNAs (miRNAs) are short non-protein- coding RNAs that function as key regulators of diverse biological processes through negative control on gene expression at the post-transcriptional level. Emerging evi- dence indicates that miRNAs play an important role in the development of human cancers, with their deregulation resulting in altered activity of downstream tumor sup- pressors, oncogenes and other signaling molecules. Recent years have seen considerable progress in miRNA research in brain tumors, particularly in glioblastomas and medul- loblastomas, providing novel insights into the pathogenesis of these malignant lesions. Expression profiling has unveiled miRNA signatures that not only distinguish brain tumors from normal tissues, but can also differentiate histotypes or molecular subtypes with altered genetic pathways. Moreover, specific miRNA subsets may have potential diagnostic and prognostic values in some brain tumors. Several deregulated miRNAs uncovered in glio- blastomas and medulloblastomas have their gene targets and the associated genetic pathways identified. This review summarizes recent findings of miRNA study in brain tumors. Keywords Brain tumors
Glioblastoma
Medulloblastoma
MicroRNA
Pituitary adenoma Introduction MicroRNAs (miRNAs) are endogenous, short (19–24 nucleotides) non-protein-coding RNAs that regulate gene expression at the post-transcriptional level [33]. The first two miRNAs, lin-4 and let-7, were discovered in the nematode Caenorhabditis elegans and were shown to play a crucial role in the timing of larval development [49, 73]. Since then, thousands of miRNAs have been found in animals, plants and even in viruses, and many animal miRNAs identified are evolutionaril