Aberrant Expression of N-Methylpurine-DNA Glycosylase Influences Patient Survival in Malignant Gliomas

Abstract

<i >Aim.</i> To examine the expression of N-methylpurine-DNA glycosylase (MPG) gene and protein in glioma samples with different WHO grades and its association with patients&#x2019; survival. <i >Methods.</i> Immunohistochemistry assay, quantitative real-time PCR and Western blot analysis were carried out to investigate the expression of MPG gene and protein in 128 glioma and 10 non-neoplastic brain tissues. <i >Results.</i> MPG gene expression level in glioma tissues was significantly higher than that in non-neoplastic brain tissues (<svg style="vertical-align:-0.30096pt;width:63.962502px;" id="M1" height="11.0625" version="1.1" viewBox="0 0 63.962502 11.0625" width="63.962502" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.0625)"> <g transform="translate(72,-63.15)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0">&lt;</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="44.810753" y="0">1</tspan> </text> </g> </g> </svg>). Immunohistochemistry also showed that MPG protein was over-expressed in glioma tissues, which was consistent with the resutls of Western blot analysis. Additionally, the expression levels of MPG gene and protein both increase from grade I to grade IV glioma according to the results of real-time PCR, immunohistochemistry and western blot analysis. Moreover, the survival rate of MPG-positive patients was significantly lower than that of MPG-negative patients (<svg style="vertical-align:-0.30096pt;width:63.962502px;" id="M2" height="11.0625" version="1.1" viewBox="0 0 63.962502 11.0625" width="63.962502" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.0625)"> <g transform="translate(72,-63.15)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0">&lt;</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="44.810753" y="0">1</tspan> </text> </g> </g> </svg>). We further confirmed that the over-expression of MPG was a significant and independent prognostic indicator in glioma by multivariate analysis (<svg style="vertical-align:-0.30096pt;width:63.962502px;" id="M3" height="11.0625" version="1.1" viewBox="0 0 63.962502 11.0625" width="63.962502" xmlns="http://www.w3.org/2000/svg"> <g transform="matrix(1.25,0,0,-1.25,0,11.0625)"> <g transform="translate(72,-63.15)"> <text transform="matrix(1,0,0,-1,-71.95,63.5)"> <tspan style="font-size: 12.50px; " x="0" y="0">𝑃</tspan> <tspan style="font-size: 12.50px; " x="10.890113" y="0">&lt;</tspan> <tspan style="font-size: 12.50px; " x="22.930502" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="29.182001" y="0">.</tspan> <tspan style="font-size: 12.50px; " x="32.307751" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="38.559254" y="0">0</tspan> <tspan style="font-size: 12.50px; " x="44.810753" y="0">1</tspan> </text> </g> </g> </svg>). <i >Conclusions.</i> Our data showed the over-expression of MPG gene and protein in human gliomas, and also suggested for the first time that MPG be an unfavorable independent prognostic indicator for glioma patients.