Hhv - 6 And The Correlation Of Brain Glioma And Its U94 / Rep Gene Expression On U251 Cell Biological Character

Glioma is one of the most common intracranial tumors, which has a highrecurrence rate and high mortality.The5-year survival rate of glioblastoma is lessthan5%. So far, the etiology and pathogenesis of glioma is still not very clear. Inrecent years, more and more studies reported that the nucleic acid and protein ofHHV-6were detectablein glioma tissues. HHV-6is a double-stranded DNA virus,belonging to the human herpesvirus β subfamily, mainly infects the CD4+T cells,monocyte-macrophage cells and glial cells. HHV-6can estabish long-term latentinfection after primary infection in early childhood.Viral genes can integrate into thehost chromosome and berepeatedly reactivated. However the role of HHV-6in thedevelopment of glioma needs to be further studied.On one hand, the interaction between virus and cell may lead to changesononcogene and tumor suppressor gene expressionby intracellular signaling pathwaysresulting in inducing transformation or malignant phenotype. On the other hand,HHV-6has activated and latent infectious modes so that viral gene expression isdistinct under different modes. Because of the existence of tumorigenic gene(HHV-6DR7) andtumor suppressor gene (HHV-6U94/rep), the role of HHV-6inglioma development may exist two sides. This study contains (1) the correlation ofHHV-6infection and glioma;(2) HHV-6infection affects primary astrocytes PHFAsand glioma cell line U251;(3) HHV-6U94/repgene suppresses maliganant phenotypeofU251.Firstly, we collected48glioma tissue samples,6glioma cyst fluid samples and13normal brain tissue samples. Nested PCR assay showed that the positive rate ofHHV-6nucleic acid was41.7%and7.7%respectively in glioma andnormal braintissue.HHV-6antigen was detectable in17glioma samples by immunohistochemicalstaining, but all normal brain tissue were negative. In addition, we isolated a kind ofHHV-6A from glioma cyst fluid. The existence of HHV-6nucleic acid and antigen insome glioma tissues indicates that HHV-6may play a role in the development of glioma.Secondly, our results showed that HHV-6could successfully infect primaryastrocyte and glioma cell line U251. The effective of HHV-6infection for host cells isdependenton cell types and infectious modes. In normal human primary astrocytes,HHV-6could induce apoptosis viacaspase-dependent and–independentways. Theacute phase of infection of HHV-6could promote the proliferation of U251cells. Thelatent phase of HHV-6not only suppressed own copy but also inhibitedtheproliferation of U251cells.Thirdly, HHV-6U94/rep gene was inserted into lentiviral expression plasmid.Lentiviral expression plasmid and helper plasmids were co-transfected into293T cellsby liposome transfection method. A large number of high-titer recombinant lentiviruswas packaged and replicated in293T cells. The U94/rep gene transferred into U251cells and expressed stably using the recombinant lentivirus. This was the foundationfor the follow-up study of U94/rep gene suppressing maliganant phenotype ofU251.Finally, the results showed that U94/rep gene could inhibit U251cells in cellproliferation, migration, invasion and angiogenesis, which mechanism may be relatedto cell cycle S phase arrest, the downregulation of MMP-2, MMP-9and VEGF,bFGF.In summary, there is a certain correlation between HHV-6and glioma. Theeffective of HHV-6infection for host cells is dependenton cell types and infectiousmodes. HHV-6U94/rep gene, one tumor suppressor gene of HHV-6, can inhibit themalignant phenotype of U251cells in vitro. These results of this study provides a newapproach and theoretical basis for the treatment of glioma.