title: Analysis of expression of microRNAs and genes involved in the control of key signaling mechanisms that support or inhibit development of brain tumors of different grades.
abstract: BACKGROUND
  MicroRNAs (miRNAs) are a class of small non-coding RNA molecules involved in the regulation of key biological processes. Different miRNAs with pro-oncogenic and anti-oncogenic properties have been identified in glioblastomas. We decided to analyze expression profiles of 10 mature miRNAs (miR-7-1, miR-10а, miR-17, miR-20а, miR-21, miR-23а, miR-26а, miR-137, and miR-222) in post-surgery glioma specimens of different grades in order to find whether the expression level correlates with tumor grades. We also measured expression of six key genes such as PTEN, p21/CDKN1A, MDR1, ABCG2, BAX, and BCL-2 involved in the regulation of critical glioma signaling pathways to establish the effect of miRNAs on these signaling mechanisms.
  
  
  METHODS
  Using RT-PCR, we performed expression analysis of 25 tumor fresh samples (grades II-IV).
  
  
  RESULTS
  We found gradual increase in miR-21 and miR-23a levels in all tumor grades whereas miR-7 and miR-137 were significantly down-regulated depending on the glioma grade. MDR, ABCG2, and p21/CDKN1A levels were significantly up-regulated while expression of PTEN was down-regulated in tumor samples compared to the normal brain tissue.
  
  
  CONCLUSIONS
  These observations provide new insights into molecular pathogenic mechanisms of glioma progression and suggest about a potential value of miRNAs as a putative diagnostic marker of brain tumors.
authors.affiliation: Department of Medical Nanobiotechnology, Pirogov Russian National Research Medical University, Moscow, Russia. Electronic address: philipkoshkin@gmail.com.
authors.forename: Philip Alexandrovich
authors.initials: PA
authors.lastname: Koshkin
authors.affiliation: Department of Medical Nanobiotechnology, Pirogov Russian National Research Medical University, Moscow, Russia. Electronic address: dimitry.chistiakov@lycos.com.
authors.forename: Dimitry Alexandrovich
authors.initials: DA
authors.lastname: Chistiakov
authors.affiliation: Department of Medical Nanobiotechnology, Pirogov Russian National Research Medical University, Moscow, Russia.
authors.forename: Alexey Georgievich
authors.initials: AG
authors.lastname: Nikitin
authors.affiliation: Burdenko Research Institute of Neurosurgery, Moscow, Russia.
authors.forename: Alexander Nikolaevich
authors.initials: AN
authors.lastname: Konovalov
authors.affiliation: Burdenko Research Institute of Neurosurgery, Moscow, Russia.
authors.forename: Alexander Alexandrovich
authors.initials: AA
authors.lastname: Potapov
authors.affiliation: Burdenko Research Institute of Neurosurgery, Moscow, Russia.
authors.forename: Dmitry Yrevich
authors.initials: DY
authors.lastname: Usachev
authors.affiliation: Burdenko Research Institute of Neurosurgery, Moscow, Russia.
authors.forename: David Ilich
authors.initials: DI
authors.lastname: Pitskhelauri
authors.affiliation: Burdenko Research Institute of Neurosurgery, Moscow, Russia.
authors.forename: Gregory Lvovich
authors.initials: GL
authors.lastname: Kobyakov
authors.affiliation: Burdenko Research Institute of Neurosurgery, Moscow, Russia.
authors.forename: Lyudmila Valentinovna
authors.initials: LV
authors.lastname: Shishkina
authors.affiliation: Department of Medical Nanobiotechnology, Pirogov Russian National Research Medical University, Moscow, Russia; Department of Fundamental and Applied Neurobiology, Serbsky State Scientific Center for Social and Forensic Psychiatry, Moscow, Russia.
authors.forename: Vladimir Pavlovich
authors.initials: VP
authors.lastname: Chekhonin
mesh_terms: D000328:Adult; D000368:Aged; D001932:Brain Neoplasms / Q000235:genetics* / Q000473:pathology*; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics*; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D060787:Neoplasm Grading; D015398:Signal Transduction / Q000235:genetics*; D055815:Young Adult
chemical_list: D035683:MicroRNAs
keywords: Expression; Glioma; Grade; MiRNA; RT-PCR; Signaling pathways