Infection And Expression Of Human Cytomegalovirus And Its Significance In Gliomas

Gliomas are the most common malignant tumors in the central nervous system and account for about 45% of intracranial tumors.Despite advances in diagnostic imaging,surgery,radiation therapy and the development of new antineoplastic agents,the prognosis of glioma patients has not been fundamentally improved.With the comprehensive standard therapy,median overall survival for patients with malignant gliomas is less than 15 months after diagnosis.Therefore,to further investigate the etiology and pathogenesis of gliomas may provide a new and more effective treatment strategy.In recent years,some studies showed that the infection of human cytomegalovirus(HCMV)and its proteins existed in human gliomas and other types of malignant tumors.These results suggested that HCMV may have certain relationship with the formation and progression of some human malignant tumors,but the results are still controversial.In the present study,we investigated the expression of immediate early gene 1-72(IE1-72)protein and phosphorylated glycoprotein 65(pp65)of HCMV in human gliomas by immunohistochemistry method,as well as the correlation between their expression level and clinicopathological features of gliomas was further analyzed.Furthermore,we detected the level of HCMV DNA in gliomas by in situ hybridization.ObjectiveTo detect the expression level of HCMV proteins and the level of HCMV DNA in gliomas,to analyze the relationship between the expression level of HCMV proteins and the clinicopathological features of gliomas,as well as to investigate the etiological relationship between HCMV infection and the initiation and development of gliomas.Methods1.175 cases of glioma tissue were obtained from the Department of Neurosurgery,Xijing Hospital by surgical resection,and 10 cases of normal human brain tissue were obtained from traumatic brain injury or hypertensive cerebral hemorrhage from the same department.The expression of IE1-72 protein of HCMV was detected by immunohistochemistry method in 125 cases of human brain glioma and 10 cases of normal human brain tissue,as well as the correlation between its expression level and the clinicopathological features of gliomas was further analyzed.2.The expression of pp65 protein of HCMV was detected by immunohistochemistry method in 175 cases of human brain glioma and 10 cases of normal human brain tissue.The relationship between the expression level of pp65 protein and the clinicopathological features of gliomas,as well as the relationship between the expression of pp65 protein and the expression of IE1-72 protein in gliomas were further analyzed.3.HCMV DNA was detected by in situ hybridization in 22 cases of WHO grade IV gliomas and its significance was further analyzed.The selected gliomas all showed positive expression of pp65 protein of HCMV by immunohistochemistry.Results1.Expression of IE1-72 protein of HCMV in human brain gliomas and normal brain tissuesThere are 90 cases showed positive staining of IE1-72 protein in 125 cases of glioma tissues and the positive expression rate was 72%.The immunoreactive signal of IE1-72 protein was located in the nucleus and / or cytoplasm,mainly located in the nucleus and partly in the cytoplasm.However,IE1-72 protein was not expressed in 10 normal human brain tissues.The expression level of IE1-72 protein in gliomas was significantly higher than that in normal human brain tissues(Z=-3.923,P=0.000).2.The relationship between IE1-72 expression level of HCMV and clinicopathological features of gliomasIE1-72 immunoreactivity intensity was enhanced significantly with gliomas pathological grade ascending(r=0.310,P=0.000),and which in malignant glioma tissues was significantly higher than that in benign glioma tissues(Z=-2.893,P=0.004).IE1-72 immunoreactivity intensity showed a significantly positive correlation with age of glioma patients(r=0.234,P=0.009),however no obvious correlation with gender(r=0.038,P=0.675)and tumor location(r=0.086,P=0.341)of glioma patients.3.Expression of pp65 protein of HCMV in human brain gliomas and normal brain tissuesThere are 138 cases showed positive staining of pp65 protein in 175 cases of glioma tissues and the positive expression rate was 78.9%.The immunoreactive signal of pp65 protein was located in the nucleus and/or cytoplasm,mainly in the nucleus.However,pp65 protein was not expressed in 10 normal human brain tissues.Expression of pp65 protein in gliomas was significantly higher than that in normal human brain tissues(Z=-4.338,P=0.000).4.The relationship between pp65 protein expression level of HCMV and clinicopathological features of gliomasImmunostaining intensity of pp65 protein was not significantly associated with the pathological grade(r=0.096,P=0.208)and malignant degree(Z=-0.960,P=0.337)of gliomas,as well as with the gender(r=0.138,P=0.069),age(r=0.016,P=0.837)and tumor site(r=-0.147,P=0.052)of glioma patients.5.The relationship between the expression level of pp65 protein and IE1-72 protein in gliomasThe expression level of pp65 protein was detected in 175 cases of gliomas,and the expression level of IE1-72 protein was detected in 125 cases among them.There was a significant correlation between their expression level(χ2=25.637,P=0.002).6.Detection of HCMV DNA in glioma tissuesThe results of in situ hybridization showed that 3 cases of gliomas were weak positive staining and 1 case was suspected positive staining of HCMV DNA among 22 cases of positive expression of pp65 protein in gliomas.The positive stainning was located in the cell nucleus.However,the other 18 cases had no obvious positive staining.Conclusions1.IE1-72 protein and pp65 protein of HCMV were over-expressed in glioma tissues while no expression of them in the normal brain tissues,and their expression level showed a significantly positive correlation.Moreover,the expression level of IE1-72 protein was enhanced significantly with gliomas pathological grade and malignant degree ascending.These results suggest that the expression of IE1-72 protein and pp65 protein of HCMV may be associated with the formation and progression of gliomas and they may have a synergistic action.2.HCMV DNA may be present in glioma tissues,due to the detection of the small number of cases and the need for optimization of experimental method,this issue still need further research.