Relationship Between MGMT Protein Expression And Promoter Methylation Of Body Fluid MGMT Gene In Human Glioma

[Objective]To determine whether the methylation status of the MGMT gene promoter in body fluids(cerebrospinal fluid,blood)of glioma patients is related to the expression level of MGMT protein in the tumor tissues and the degree of correlation;and whether the promoter of the MGMT gene in the body fluid can be methyl The detection of MGMT protein in place of tumor tissue was used to guide the treatment of glioma patients.[Methods]This study has been approved by the Ethics Committee of Yunnan Provincial Cancer Hospital and informed consent has been signed with the patient.Collected 76 cases of glioma patients excluded from other parts of the body's tumors at the Department of Neurosurgery,Yunnan Provincial Tumor Hospital from June 2014 to October 2017.Serum and cerebrospinal fluid,age range 7-76 years,39 male patients There are 37 female patients.The pathological diagnosis results of 76 cases of glioma patients were astrocytoma in 16 cases,anaplastic astrocytoma in 21 cases,oligodendroglioma in 7 cases,and glioblastoma in 32 cases.Pathological classification and classification According to WHO classification and classification criteria of central nervous system tumors,including 32 cases of grade II,44 cases of grade ?-?.The expression of MGMT protein in tumor tissue and the methylation status of MGMT gene promoter in serum and cerebrospinal fluid were detected by immunohistochemistry and MSP method respectively in 76 cases of glioma.The relationship between methylation results of MGMT gene promoter in body fluids and the corresponding expression level of MGMT protein in tumor tissues and the relationship with clinical pathological characteristics of patients were analyzed.The detection rate of MGMT gene promoter methylation in serum and cerebrospinal fluid was compared using McNemar test.Kappa consistency test was used to compare the consistency of methyl ation detection results of MGMT gene promoter and cerebrospinal fluid from the same patient.The relationship between the methylation status of MGMT promoter in serum and cerebrospinal fluid and the clinicopathological features such as sex,age,pathological grade,classification,etc.was tested by Chi-square test.Spearman correlation test was used to analyze the methylation status of MGMT gene promoter and MGMT protein expression in glioma.[Results]1.The MGMT promoter methylation was detected in 49(64.5%)and 56(73.7%)of 76 glioma patients,respectively,in serum and cerebrospinal fluid(P=0.219).The homogeneity of MGMT promoter methylation in serum and cerebrospinal fluid of the same patient was poor(Kappa=0.299,P=0.008).2.?Thirty-two patients with WHO grade II glioma had 19(59.4%)and 22(68.8%)methylation of MGMT promoters,and 44 WHO grade III-IV glioma p atients.Methylation of the MGMT promoter was detected in 30(68.2%)and 34(77.3%)cerebrospinal fluids,respectively.There was no correlation between methylation levels of cerebrospinal fluid and blood MGMT promoter in patients with WHO II and WHO III-IV(P=0.405 in the cerebrospinal fluid and P=0.428 in the blood).?In 16 cases of astrocytoma,10(62.5%)and 12(75.0%)of the astrocytoma patients bad MGMT gene promoter methylation,and 7 cases of oligodendroglio ma blood and cerebrospinal fluid were 3(42.9).Methylation of MGMT gene p romoter was detected in 3%and 3(42.9%)samples;MGMT gene promoter was detected in 15(71.4%)and 16(76.2%)samples of blood and cerebrospinal fluid in 21 cases of degenerate astrocytomas respectively.Methylation;The MGMT gene promoter methylation was detected in 21(65.6%)and 25(78.1%)of the blood and cerebrospinal fluid of 32 patients with glioblastoma,respectively.T here was no correlation between methylation status of cerebrospinal fluid and b lood MGMT gene promoter and pathological types(blood P=0.795,cerebrospin al fluid P=0.540).? Methylation of the MGMT promoter was detected in 25(64.1%)and 31(79.5%)of the serum and cerebrospinal fluid of 39 male patients.Serum and cere brospinal fluid levels were 24(64.9%)and 25(67.6)in 37 female patients,res pectively.Methylation of the MGMT promoter was detected in%);there was no association between methylation of MGMT promoter in cerebrospinal fluid i n male patients and female patients(P=0.238);no correlation was found in me thylation of blood MGMT promoter between male patients and female patients(P =0.945);?Methylation of the MGMT promoter was detected in 3(50.0%)and 4(66.7%)of the serum and cerebrospinal fluid in 6 patients aged<20 years,respect ively;serum and cerebrospinal fluid in 18 patients aged 20-40 years were 14(77.8).%)and 14(77.8%).Methylation of the MGMT promoter was detected;s erum and cerebrospinal fluid in 39 patients aged 40-60 years were 24(61.5%).Methylation of MGMT promoter was detected in 28(71.8%)samples;methylat ion of MGMT promoter was detected in 8(61.5%)and 10(76.9%)of serum and cerebrospinal fluid in 13 patients>60 years old respectively;Methylation o f MGMT promoter was not correlated in cerebrospinal fluid of patients with a ge(P=0.930);there was no correlation between blood methylation of MGMT p romoter in patients of all ages(P=0.545);3.?Among the 76 glioma patients,methylation of MGMT gene promoter was positive in 56 cerebrospinal fluids,and methylation of MGMT gene promoter was negative in cerebrospinal fluid in 20 patients.Among the 56 patients with methylation-positive MGMT promoter in cerebrospinal fluid,the expression of MGMT protein in tumor tissues was suspiciously positive,positive,and strong 1y positive in 28 cases,22 cases,and 6 cases,respectively;in 20 patients with methylation-negative MGMT promoter methylation There were 4 cases,4 case s,and 12 cases of MGMT protein expression suspiciously,positively,and stron gly positively.Methylation of MGMT gene in cerebrospinal fluid was negativel y correlated with tumor MGMT expression(P=0.000).?Among the 76 glioma patients,methylation of MGMT gene promoter was p ositive in 49 cases of cerebrospinal fluid,and methylation of MGMT gene pro moter was negative in 27 cases.In 49 patients with MGMT promoter methylat ion-positive patients,the expression of MGMT protein in tumor tissues was sus piciously positive,positive,and strongly positive in 13 cases,18 cases,and 18 cases,respectively;in 27 cases of blood MGMT promoter methylation-negativ e patients The MGMT protein expression was suspiciously positive,positive,an d strongly positive in 10 cases,11 cases,and 6 cases,respectively.There was no correlation between MGMT promoter methylation and tumor MGMT expre ssion(P=-0.153).[Conclusion]1.Methylation of MGMT gene promoter in cerebrospinal fluid may become a prognostic biomarker for glioma patients and predict whether gliomas are r esistant to alkylating agents.2.Methylation of MGMT gene promoter was negatively correlated with MGM T protein expression in cerebrospinal fluid.There was no correlation betwee n MGMT gene promoter and methylation detection of MGMT gene promot er in cerebrospinal fluid.3.The positive rate of methylation of MGMT gene promoter in cerebrospinal fluid and serum was not correlated with the pathological grade and type,g ender,and age of glioma patients.