title: miRNA arm selection and isomiR distribution in gastric cancer.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are small non-protein-coding RNAs. miRNA genes need several biogenesis steps to form function miRNAs. However, the precise mechanism and biology involved in the mature miRNA molecules are not clearly investigated. In this study, we conducted in-depth analyses to examine the arm selection and isomiRs using NGS platform.
  
  
  METHODS
  We sequenced small RNAs from one pair of normal and gastric tumor tissues with Solexa platform. By analyzing the NGS data, we quantified the expression profiles of miRNAs and isomiRs in gastric tissues. Then, we measured the expression ratios of 5p arm to 3p arm of the same pre-miRNAs. And, we used Kolmogorov-Smirnov (KS) test to examine isomiR pattern difference between tissues.
  
  
  RESULTS
  Our result showed the 5p arm and 3p arm miRNA derived from the same pre-miRNAs have different tissue expression preference, one preferred normal tissue and the other preferred tumor tissue, which strongly implied that there could be other mechanism controlling mature miRNA selection in addition to the known hydrogen-bonding selection rule. Furthermore, by using the KS test, we demonstrated that some isomiR types preferentially occur in normal gastric tissue but other types prefer tumor gastric tissue.
  
  
  CONCLUSIONS
  Arm selections and isomiR patterns are significantly varied in human cancers by using deep sequencing NGS data. Our results provided a novel research topic in miRNA regulation study. With advanced bioinformatics and molecular biology studies, more robust conclusions and insight into miRNA regulation can be achieved in the near future.
authors.affiliation: Genomics Research Center, Academia Sinica, Taipei, Taiwan.
authors.forename: Sung-Chou
authors.initials: SC
authors.lastname: Li
authors.forename: Yu-Lun
authors.initials: YL
authors.lastname: Liao
authors.forename: Meng-Ru
authors.initials: MR
authors.lastname: Ho
authors.forename: Kuo-Wang
authors.initials: KW
authors.lastname: Tsai
authors.forename: Chun-Hung
authors.initials: CH
authors.lastname: Lai
authors.forename: Wen-chang
authors.initials: WC
authors.lastname: Lin
mesh_terms: D001483:Base Sequence; D020869:Gene Expression Profiling; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics*; D013274:Stomach Neoplasms / Q000235:genetics*
chemical_list: D035683:MicroRNAs