Expression of p53, epidermal growth factor receptor, Ki-67 and O6-methylguanine-DNA methyltransferase in human gliomas

-methylguanine-DNA methyltransferase (MGMT), and to analyze the correlation between their expression and the histological grade of the tumors in 152 patients with gliomas. The tumors were classified according to the recommendations of the World Health Organization (WHO; 2007) into grade I (n=9), grade II (n=56), grade III (n=52) and grade IV (n=35). The expression of p53, Ki-67, EGFR and MGMT was analyzed using immunohistochemistry. The frequency of p53 immunopositivity was significantly lower in grade I gliomas than in grades II, III and IV. The frequency of EGFR immunopositivity was significantly higher in grade III and IV gliomas compared with grades I and II. The mean Ki-67 labelling index (LI) significantly increased in the higher glioma grades. The expression of MGMT in grade I and II tumors was not significantly different from that of grade III and IV tumors. The present data indicate that the expression of EGFR and Ki-67 is significantly correlated with the histological grade of the glioma, but that the expression of p53 and MGMT is not associated with the tumor grade.