[Correlation analysis of MAP2K6 expression in nasopharyngeal carcinoma tissues with EBV infection and clinical...

Objective:To investigate the expression level of mitogen-activated protein kinase kinase 6（MAP2K6） in human nasopharyngeal carcinoma（NPC） tissues and its correlation with Epstein-Barr virus（EBV） infection and clinical prognosis. Methods:Pathological sections of cancer tissues and paired adjacent non-tumor tissues were collected from 78 newly diagnosed NPC patients admitted to the Third Affiliated Hospital of Kunming Medical University from January 2018 to December 2018. Immunohistochemical staining was performed to detect the relative expression level of MAP2K6 protein. Fresh cancer tissues and adjacent non-tumor tissues wereobtained from 18 patients, and reverse transcription-quantitative polymerase chain reaction（RT-qPCR） was used to measure the relative expression level of MAP2K6 mRNA. The chi-square test was employed to analyze the correlation between MAP2K6 protein expression and clinicopathological characteristics of NPC. The Kaplan-Meier method was used to plot survival curves and evaluate survival time, and the log-rank test was applied to verify the factors related to prognosis. Multivariate Cox regression analysis was conducted to identify independent risk factors affecting the prognosis of NPC. According to the serum EBV DNA copy number, the Spearman test was used to analyze the correlation between the relative expression level of MAP2K6 and EBV DNA copy number. Results:Compared with cancer tissues, the expression level of MAP2K6 mRNA in adjacent non-tumor tissues was significantly increased, and the difference was statistically significant（P<0.05）. The positive expression rate of MAP2K6 protein in adjacent non-tumor tissues was 62.8%, which was significantly higher than that in cancer tissues, and the difference was statistically significant（P<0.05）. Expression of MAP2K6 was correlated with T stage, N stage, VCA-IgA and EBV DNA copy number（P<0.05）. The expression level of MAP2K6, T stage, VCA-IgA and EBV DNA copy number had significant effects on the survival rate of NPC patients（P<0.05）. MAP2K6 expression and EBV DNA copy number were independent risk factors affecting the overall survival of NPC patients. When divided into 2 groups or 4 groups according to EBV DNA copy number, the expression level of MAP2K6 protein was negatively correlated with EBV DNA copy number. Conclusion:MAP2K6 is highly expressed in adjacent non-tumor tissues, correlates with the clinicopathological characteristics of patients, is positively correlated with prognosis, and negatively correlated with EBV DNA copy number. It exerts a tumor-suppressive effect in NPC and is expected to be a therapeutic target or biomarker for the prognostic evaluation of NPC.