Abstract: Objective To investigate the expressions of histone lysine-specific demethylase 1 (LSD1), O⁶-methylguanine DNA methyltransferase (MGMT) and cell proliferationassociated antigen Ki-67 in high-grade glioma and their influences on prognosis. Methods Sixty-five cases of grade Ⅲ and Ⅳ glioma confirmed by pathology from January 2011 to June 2017 in the First Affiliated Hospital of Xinjiang Medical University were selected. Immunohistochemistry (SP method) was used to detect the expressions of LSD1, MGMT and Ki-67 in pathological specimens. The therapeutic effect was evaluated by long-term follow-up. The relationships between the three markers and pathological grade, progression-free survival (PFS) and overall survival (OS) were analyzed. Results The overall positive rates of LSD1, MGMT and Ki-67 in the 65 highgrade glioma specimens were 70.8% (46/65), 60.0% (39/65) and 100.0% (65/65), respectively. There were no significant differences in the expressions of LSD1 and MGMT in grade Ⅲ and Ⅳ glioma (χ2=1.588, P=0.208, χ2=0.013, P=0.908). Ki-67 expression (+), (++), (+++) in grade Ⅳ glioma were observed in 18, 19 and 11 cases, respectively. Ki67 expression (+), (++) in grade Ⅲ glioma were observed in 11, 5 cases, and 1 case was (+++), and the difference in expression intensity between the two groups was statistically significant (Z=-2.083, P=0.037). Log-rank test showed that the positive expressions of LSD1, MGMT and Ki67 were negatively correlated with the PFS of patients with highgrade glioma (χ2=12.217, P=0.007; χ2=4.446, P=0.035; χ2=12.536, P=0.002), also were negatively correlated with OS (χ2=11.708, P=0.008; χ2=6.637, P=0.010; χ2=11.807, P=0.003). Grade Ⅳ patients were more likely to have relapse progression than grade Ⅲ patients (χ2=6.573, P=0.010), and OS was shorter (χ2=3.974, P=0.046). Cox proportional hazards model analysis showed that the expressions of LSD1 (HR=1.361, 95%CI: 1.094-1.694, P=0.006; HR=1.406, 95%CI: 1.117-1.771, P=0.004) and Ki-67 (HR=1.703, 95%CI: 1.175-2.468, P=0.005; HR=1.778, 95%CI: 1.209-2.616, P=0.003) were the independent prognostic risk factors for PFS and OS of patients with high-grade glioma. Correlation analysis results showed that the expression of MGMT was positively correlated with the expression of LSD1 (r=0.406, P=0.001). Conclusion LSD1, MGMT and Ki-67 have higher positive expression rates in high-grade glioma. MGMT is a prognostic factor for highgrade glioma, and LSD1 and Ki-67 can be used as independent predictors of prognosis for high-grade gliomas.

Key words: Glioma, O(6) -methylguanine DNA methyltransferase, Ki-67 antigen, Prognosis, Lysine specific demethylase 1