The Effect And Mechanism Of SV2B In Inhibiting Glioma Progression Through FAK/PI3K/AKT Signaling Pathway

Background:Glioma is the most common primary malignant tumor of the central nervous system(CNS),with glioblastoma(GBM)being the most malignant pathological subtype,accounting for 48.6%of CNS malignancies and a 5-year survival rate of less than 5%.As our understanding of the molecular subtypes of glioma and the corresponding changes in signaling pathways during tumorigenesis improves,diagnostic and therapeutic strategies for glioma patients may change accordingly,promising to improve the prognosis of glioma patients.Cell membrane glycoproteins and their corresponding receptors are associated with the origin and development of several human cancer types,including glioma and breast cancer.In vertebrates,synaptic vesicle glycoprotein 2B(SV2B)plays an important role as a 12th transmembrane glycoprotein in the release of neurotransmitters,the formation of endocrine vesicles,and functions as a bridge to communicate with extracellular matrix components.In addition,there is increasing evidence recently that SV2B exhibits an important regulatory role as an inhibitory factor in tumor development.In addition,we further explored that SV2B can inhibit the PI3K/Akt pathway via focal adhesion kinase(FAK),a tyrosine kinase overexpressed in cancer cells,and existing studies suggest that FAK plays a key role in tumorigenesis and malignant progression,especially in the epithelialmesenchymal transition of tumor cells.FAK can receive extracellular signals from cellular transmembrane receptors,and the subsequent signaling cascade is activated and transduced in a variety of cellular activities,specifically,tumor stem cell proliferation and apoptosis are affected by it,and tumor cell migration behavior is regulated by it.In summary,we summarize the functional role,molecular mechanisms and clinical perspectives of SV2B in glioma and suggest that this protein may become a key molecule in the treatment and prognosis of glioma patients in the future.Objective:The aim of this study was to investigate the relationship between SV2B and FAK/PI3K/Akt and to elucidate the potential molecular mechanisms that regulate the biological behavior of glioma cells through in vivo and in vitro experiments,and to provide a new perspective for the treatment of glioblastoma.Methods:The expression of synaptic vesicle glycoprotein 2B(SV2B)in glioma patients,the variation of SV2B in glioma and the effect of SV2B on the overall survival of glioma patients were examined in the bioinformatics database The Cancer Genome Atlas(TCGA).In glioblastoma cells,SV2B overexpression(SV2B mimics)and SV2B knockdown(shSV2B)cell models were constructed to enhance or inhibit the expression of SV2B in glioma cells U-87MG and U-251.qRT-PCR and Western Blot assays were performed to detect the transfection efficiency.After the successful construction of SV2B overexpression or knockdown glioblastoma cell lines,the effects of SV2B on the biological properties of glioblastoma cells,such as proliferation,migration,apoptosis and epithelial-mesenchymal transition(EMT),were examined by CCK-8 assay,clone formation assay,EdU assay,wound healing assay,Transwell migration assay,flow apoptosis assay and Western Blot assay.A bioinformatics approach was used to predict the downstream signaling pathways of SV2B,and transcriptome sequencing was used to further predict the FAK/PI3K/Akt signaling pathway as a signaling pathway for SV2B to regulate glioblastoma cells.The expression levels of SV2B,FAK,PI3K,Akt and GSK3β were examined by Western Blot assay.Finally,xenografted tumor model was constructed to verify the effect of SV2B on glioma proliferation in vivo and on the overall survival rate of the mouse model.Results:1.SV2B is lowly expressed in glioma tissues;overexpression of SV2B inhibits proliferation,migration and apoptosis of glioblastoma cells.knockdown of SV2B promotes cell proliferation,migration and apoptosis.2.SV2B inhibited the EMT process in glioma cells.Overexpression of SV2B increased the expression of EMT-related molecules E-cadherin,and significantly decreased the expression of vimentin.3.Overexpression of synaptic vesicle glycoprotein 2B(SV2B)significantly inhibited the activation of FAK/PI3K/Akt signaling pathway in U87 and U251 cells.4.Overexpression of SV2B exerted a significant inhibitory effect on tumor growth in intracranial xenograft tumor mouse models,and the overall survival rate was significantly prolonged in the overexpression group.Conclusions:Synaptic vesicle glycoprotein 2B is lowly expressed as anti-oncogene in glioma,and it plays a role in inhibiting the malignant progression of glioma by regulating the transduction process of FAK/PI3K/Akt signaling pathway and interfering with the epithelial-mesenchymal transition(EMT)of glioblastoma cells.In in vivo and ex vivo experiments,SV2B overexpression exerted inhibitory effects on proliferation,migration,apoptosis and EMT of glioblastoma cells.Therefore,SV2B is expected to be used as a prospective target for glioblastoma diagnosis and treatment,providing a new idea for glioblastoma clinical treatment.