Expression of the DNA Repair Gene, N-Methylpurine-DNA Glycosylase in Astrocytic Tumors

ABSTRACT

OBJECTIVE: This study is designed to investigate the association of tumorigenesis with DNA repair gene, N-methylpurine-DNA-glycosylase(MPG) in astrocytic tumors. METHODS: MPG mRNA expression and localization in the 30 astrocytic tumors and 7 tumor-adjacent brain tissues was examined by reverse transcriptase-polymerase chain reaction(RT-PCR) and RNA in situ hybridization. Expression and intracellular localization of MPG protein was determined by immunohistochemistry. Statistical analysis was performed by ANOVA with a p value<0.05 considered statistically significant. RESULTS: MPG mRNA expression in RT-PCR was significantly higher in grade IV tumor tissues than in brain tissues adjacent to tumor or in grade II-III astrocytic tumor tissues(p<0.05). MPG mRNA in in situ hybridization was detected both in brain tissues adjacent to tumor and in astrocytic tumor tissues, regardless of the tumor grades. However, MPG protein localization in immunohistochemical study was detected only in the nucleus of all tumor tissues. In brain tissues adjacent to tumor, immunohistochemical study for MPG was not stained both in the nucleus and in cytoplasm. CONCLUSION: These results suggest MPG's role in human astrocytic tumors and raise the possibility that the increased mRNA level and intracellular localization could be associated with astrocytic tumorigenesis. Further studies about control of MPG gene expression in astrocytic tumors are warranted.