The Relationship And Significance Of LDHA, IDH1 And Mutant P53 Protein In Gliomas

Background and ObjectiveGlioma is the most common type of malignant brain tumor.It is a highly invasive tumor with a high recurrence rate and a poor prognosis.The pathological classification and grade of glioma have been identified as independent prognostic factors,which serve as a valuable guide for a clinician to select options of treatment and evaluate the progress of disease.These years,research in gliomas has already developed into a molecule level.Lactate dehydrogenase(LDH)is an enzyme that participates in the process of turning sugar into energy for cells to use.It has been know that glioma consumes a large amount of sugar,where LDH catalyzes the conversion of sugar.LDHA,one of the isozymes of LDH,is expressed in various types of human tumor.However,the role of LDHA in glioma and its value in the diagnosis of glioma is not yet elucidated.P53 is classified as a tumor suppressor gene.Mutant P53 expression has been reported to promote tumor development.In glioma,P53 mutation occurs in the early stage of tumor and is highly correlated with the progress of the disease.IDH1 is an enzyme that participates in the process of tricarboxylic acid cycle.It plays an important role in the diagnosis and prediction prognosis of gliomas.In this study,we first measured LDHA,IDH1 and mutant P53 protein expression in glioma.Then we investigated their association with the pathological classification and grade of glioma.Further we analyzed the role of LDHA and P53 expression in the prognostic prediction of glioma.Materials and Methods1.Materials and Groups:68 samples of glioma tissues were collected from the second affiliated hospital of Guangzhou medical university in the period of January 2010 until December 2015.All cases were independently and repeatedly reviewed by two pathologists,according to the WHO standard in tumor diagnosis in central nerve system.Patients of these cases did not receive any chemotherapy or radiotherapy prior to the surgery.2.Methods:(1)The expression of LDHA and mutant p53 protein measured in glioma tissues using immunochemistry envision two-step assays and further quantified by Imageproplus software based on the positive-unit value.In addition,the association of LDHA and mutant P53 with the clinical pathological characteristics of glioma was analyzed.IDH1 mutation was also measured in glioma tissues using immunochemistry Envision two-sep assays and its association with the clinical pathological characteristics of glioma was analyzed.(2)Detected the expression of LDHA and mutant p53 protein in glioma tissues of different types by application of Imageproplus image analysis system test LDHA and mutant p53 protein-positive units(PU)value,then analyze the changing of LDHA or mutant p53 protein expression intensity between different types of glioma tissues,and analyze the relations between clinical and pathological features of brain cancer.(3)Then analysis the expression of LDHA protein and mutant p53 protein PU value of glioblastoma tissue.To analysis the threshold of LDHA protein or mutant p53 protein PU value in the diagnosis and differential diagnosis of glioblastoma.(4)In gliomas,if IDH1 expression is negative in immunochemistrythen the sample will be further validated by PCR to detect.(5)68 patients with glioma were followed-up for their prognosis via telephone.Factors that affect the prognosis were recored and analyzed.(6)SPSS 16.0 software was used to perform the statistical analysis.The comparisons of qualitative data were made with the chi-square test.Comparisons between more than two groups were performed with One-way ANOVA or Welch test;multiple comparisons between groups were performed with LSD,S-N-K or Dunnett’s test.Comparisons between two groups were made with an independent-sample t-test.Futher pari wise comparisons were made with a student’s paired t-test.The survival time of sigle factor was performed with the Kaplan Meier-method,and the Log-Rank was used for the significance test.The survival time of multifactor different levels was perfomed with the Cox regression model.Difference was regarded as significant if P<0.05.Results1.Detection of isocitrate dehydrogenasel(IDH1)in gliomas tissuesThere are significant differences of IDH1 mutation among gliomas of different pathological classifications and grades.The IDH1 mutation rate of diffuse astrocytes tumor and oligodendrocytes are higher than glioblastomas.2.Detection of IDH1 gene in gliomasAccroding to the results of IDH1 gene measurement in gliomas,there are 41 out of 68 cases were IDH1 mutation.20 out of 31 cases were diagnosed as pGBM,11 out of 31 cases were sGBM.3.Analyze of LDHA and mutant P53 protein expression in glioma tissuesLDHA or mutant p53 high-expression could be detected in 51.5%(35/68)cases and 44.1%(30/68)cases,respectively.The co-high expression of LDHA/mutant p53 was observed in 20 cases(29.4%).High expression of LDHA alone was always found in high grade gliomas,and mutant p53 high expression was usually observed in glioblastoma.There was a close relationship between high-expression of LDHA and the age of patients(P=0.030).There was a close relationship between co-expression of LDHA/mutant p53 and glioblastoma(P=0.005),or gliomas with high histological grading(P=0.002).The PU value of LDHA and mutant p53 protein expression in glioblastoma tissue are higher than other glioma tissue(P<0.05).There was a close relationship found between the PU value of LDHA and the age,gender of patients(t=8.329,P=0.005).There is a significant difference of LDHA expression(PU value)in between pGBM and sGBM.4.The diagnosis analysis of LDHA and mutant p53 protein expression in glioma tissuesIf the PU value of LDHA was equal to 25.89,the specificity was equal to 100%.And the PU value of mutant p53 was equal to 33.81.The specificity was equal to 100%.5.The relations between the prognosis of patients with glioma and LDHA,mutant p53 or IDH1 expressionLower LDHA expression is associated with longer survial of glioma patients.IDH1 mutation is related to a better prognosis in glioma patients.Conclusions1.IDH1 mutation is associated with the classification and grade of gliomas.2.The IDH1 mutation is mainly in diffuse star cell tumor and oligodendroglial tumors.In glioblastoma,pGBM has a higher proportion,but the rate of sGBM is not low.3.Analysis of LDHA combined with mutant p53 expression helps clinicians to identify the pathological grade of glioma,especially the high-graded glioma,as well as in the diagnosis of GBM.There is a significant difference of LDHA expression in between pGBM and sGBM.Thus,the PU value of LDHA helps to distinguish pGBM and sGBM.4.When the PU value of LDHA≥25.89 or p53≥33.81,the biopsy will be diagnosied as GBM.5.The prognosis of glioma patients is associated with the classification of glioma.Patients with GBM tend to have a worse prognosis compared to patients with other brain cancer.