Selected miRNAs And Their Target Genes Alterations In Primary Glioblastoma Patients

Izabela ZAWLIK, Center for Innovative Research in Medical and Natural Sciences, Poland
KOPAńSKA M. 1,2 , CZECH J. 1,2 , GABłO N. 1,2 , SZYBKA M. 3 , KULCZYCKA-WOJDALA D. 4 , SZYMAńSKA B. 4 , BRAUN M. 5 , JESIONEK-KUPNICKA D. 5 , TRABSKA-KLUCH B. 6,7

1 Department of Genetics, Chair of Molecular Medicine, Faculty of Medicine, University of Rzeszow, Rzeszow, Poland
2 Laboratory of Molecular Biology, Center for Innovative Research in Medical and Natural Sciences, University of Rzeszow, Rzeszow, Poland
3 Department of Microbiology and Laboratory Medical Immunology, Faculty of Medicine, Medical University of Lodz, Lodz, Poland
4 Central Scientific Laboratory, Medical University of Lodz, Lodz, Poland
5 Department of Pathology, Chair of Oncology, Medical University of Lodz, Lodz, Poland
6 Department of Medical Biochemistry, Medical University of Lodz, Mazowiecka 6/8, 92-215 Lodz, Poland
7 Department of Radiotherapy, Medical University of Lodz, Paderewskiego 4, 93-509, Lodz, Poland

PURPOSE: Glioblastoma (GB) carries complex genetic alterations resulting in a different molecular and epidemiological profile. There is increasing evidence that the altered miRNA expression plays an important role in GB development. The aim of the study was to examine expression of selected miRNAs and to assess the relationship between miRNA expression and alterations of their target genes and clinical features in primary GB.
METHODS: Tumor samples were obtained from 49 patients with primary glioblastoma. We used qPCR method for evaluation of miR-125b, -181, -21, -34a and -648, TP53 and MGMT expression level. For TP53 and MGMT protein expression we used immunohistochemistry. We used sequencing analysis for detection of TP53 mutations (5-8 exons). Additionally we used MS-PCR method for analysis of MGMT methylation status.
RESULTS: We found that TP53 mRNA level was negatively correlated with miR-34a level in patients with IHC-detected TP53 overexpression, whilst TP53 mRNA level was positively correlated with miR-34a level in patients without IHC-detected TP53 overexpression. MGMT mRNA was negatively correlated with miR-125b level only in patients without MGMT methylation. MGMT mRNA level in MGMT-methylated patients was significantly lower than in patients without MGMT methylation. We found a tendency towards a worse survival of patients with MGMT methylation.
CONCLUSION: Expression of the microRNAs and their potential target genes are dysregulated in GB. Epigenetic modification of MGMT gene may play an important role in regulation of MGMT transcription and may be a prognostic factor for survival of glioblastoma patients.
FUNDING SOURCE: This study was supported by the grant of the National Center of Science, Poland, 2011/01/B/NZ4/03345.