GFAP expression in varying degrees of glioma

Abstract

Background and Aim: Glial fibrillary acidic protein (GFAP) is an intermediate filament that provides mechanical support to astrocytes. Rs2070935 is single nucleotide polymorphism found in the promoter region of GFAP that could affect transcriptional activity. The aim of this study is to investigate GFAP expression at mRNA, protein levels in varying degrees of glioma and evaluate possible links with polymorphisms of rs2070935. Materials and Methods: Sample size of 50 glioma tumors was investigated. GFAP expression at mRNA level was identified using quantitative reverse transcription polymerase chain reaction (qRT-PCR) with SYBR GREEN dye. Translational activity of the following gene was detected using western blot assays. Rs2070935 genotypes were identified using qPCR with TaqMan probes. Results: This study found that grade II gliomas exhibited greater mean GFAP mRNA and protein expression than grade IV tumors (p<0.0001). GFAP transcriptional activity correlated negatively with increasing tumor grade (r=0.6469, p<0.0001). Comparison of GFAP transcriptional and translational activities revealed a positive correlation (r=0.6546, p<0.0001). Rs2070935 CC homozygotes featured greater amounts of total GFAP protein in grade II glioma, compared to CA heterozygotes (p=0.0238). Rs2070935 AA genotype is associated with poor prognosis for glioblastoma patients (p=0.0007). Conclusions: A negative correlation between GFAP expression and glioma grade was observed. Rs2070935 is a potential prognostic marker for glioblastoma patients. Associations were discovered in grade II gliomas between increased GFAP protein levels and CC genotype of rs2070935.