| ObjectiveGlioma is the most common primary intracranial malignancy.With the exception of the most common pediatric glioma,hairy cell astrocytoma(WHO class Ⅰ).which is clearly distinguishable from the surrounding tissue and can be removed,most gliomas are diffusive.Diffuse gliomas can be divided into low grade gliomas(LGGs,WHO class Ⅱ)and high grade gliomas(HGGs,WHO Ⅲ and Ⅳ)based on their growth rate.Glioblastoma multiforme(GBM)is the most malignant high grade glioma(HGGs,WHO Ⅲ and Ⅳ).GBM cells grow rapidly,and can rapidly invade near normal tissues.The tumors are of various shapes and cannot be distinguished from the surrounding normal tissues for surgical resection.From 2007 to 2011,the incidence of primary brain tumors was 21.4 per 100,000 people,and the incidence of glioma was 6.6 per 100.000 people,about half of which were glioblastomas.The incidence of glioblastoma(per 100,000 people)generally increases with age,from 0.15 in children and 0.41 in young people,to 13.1 in the 65-75 age group,75 to 84 years old.15.0 cases of the group.Depending on the reporting country/organization,the annual incidence of GBM is between 0.6 and 3.7 per 100,000 people.The age group with the highest incidence of anaplastic astrocytoma and GBM is 75 to 84 years old,and the age with the highest incidence of oligodendroglioma is 35 to 44 years old.Hair cell astrocytoma is the most common type of glioma in children,with an annual incidence of 0.9 cases per 100,000 people.Glioblastoma is a fatal disease,with most patients dying within 15-18 months of diagnosis,and less than 5%of patients can survive for more than 5 years.Even in the more favorable clinical trial population,the 5-year survival rate will not exceed 10%.The prognosis of malignant glioma is very poor.The worst prognosis of glioblastoma was a median survival of 14.6 months.Age<50 years,and complete macroscopic tumor resection is associated with longer survival.Currently,the standard treatment for malignant glioma is maximum safe surgical resection,postoperative radiotherapy,and then adjuvant chemotherapy with temozolomide.Due to the aggressive growth characteristics of malignant gliomas,there is very little complete resection.Intraoperative fluorescence-guided techniques,such as 5-aminolevulinic acid(5-ALA),can increase the rate of resection,but do not improve overall survival in patients with malignant glioma.Radiation therapy has been initiated in patients with intracranial tumors since the 1950s,but this technique has been slow to develop.One of its characteristics is anti-radiation therapy for glioma stem cells(GSCs).Studies have shown that glioblastoma originates from glioma stem cells.GSCs are resistant to radiation and chemotherapy and are the main cause of recurrence of glioblastoma.This makes GSCs a potential target for immunotherapeutic strategies.One of the most promising strategies that may be believed to be active immunotherapy is the use of dendritic cell(DC)vaccines to enable the host immune system to distinguish and eradicate GSCs.Temozolomide is the most common and effective chemotherapeutic drug for the treatment of malignant glioma.It is converted to the active metabolite methyltriazolium carboxamide at physiological pH,resulting in the formation of a methyl adduct at the guanine 06 position in the DNA.This methylation results in a mismatch to thymine during DNA replication and leads to DNA strand breaks that ultimately lead to apoptosis.However,the result depends on the promoter methylation status of 06-methylguanine methyltransferase(MGMT).MGMT actively repairs DNA damage caused by temozolomide treatment by removing the 06-methyl adduct.In fact,the greatest survival benefit provided by temozolomide treatment is a tumor that is methylated against the MGMT gene,at which point the expression and activity of this repair protein is reduced.Almost all patients with malignant glioma who have been treated will relapse,highlighting the importance of improving the effectiveness and development of existing treatments.In recent years,with the increasing understanding of the biological characteristics of glioma,more and more precise targeted therapy has become a research hotspot.However,these studies are still in their infancy,and there are basically no relevant clinical trials.There is still a long way to go in the future.Despite aggressive surgery,radiation therapy,and chemotherapy,unfortunately,any pathological grade of intracranial glioma recurrence is inevitable.In general,it is due to initial treatment failure or resistance and is often reflected in changes in tumor biology,which makes subsequent treatments more difficult and often ineffective.Recurrent tumors are more aggressive,have a faster growth rate,and have a broader range of brain parenchymal infiltration.The regrowth of LGG is about 50%with malignant transformation,which is closely related to the initial resection range,tumor volume and degree of enhancement.The prognosis of recurrent HGG is poor,with median survival ranging from 3 to 9 months.A short interval between primary treatment and tumor recurrence/regeneration can lead to worse outcomes.SIL1 is also referred to as BiP-associated protein(BAP)and regulates its activity as a nucleotide exchange factor of BiP.BiP and SIL1 are ubiquitous in human tissues.Aberrant expression or structural destruction often leads to abnormal accumulation of cellular proteins,impaired ER homeostasis,and even apoptosis.However,it is interesting that the loss of function of SIL1 leads to the fragility of certain tissues,especially the nervous system and skeletal muscles.In addition,SIL1 plays a protective role in neurodegenerative diseases and neuromuscular diseases such as Alzheimer disease(AD)and Marinesco-Sjogren syndrome(MSS).Audrey Filezac and L’Etang et al.found that SIL1 protein shows different levels of expression in different motoneurons in a mouse model of ALS,and knocking out SIL1 disrupts ER homeostasis and exacerbates the degree of ALS.Zan-Chao Liu et al.reported that SIL1 expression was decreased in AD mouse model,and SIL1 overexpression could significantly reduce tau hyperphosphorylation and GSK-3β activation associated with BiP elevation in ER stress.Jennifer Howes et al.found that a C-terminal mutation that disrupts the structural integrity of SIL1 causes Marinesco-Sjogren syndrome.Since the expression of SIL1 is closely related to the function of the nervous system,we speculate that SIL1 may play a role in neurological tumors such as gliomas.To date,there has been little research on the expression of SIL1 in glioma and its role in the pathophysiology of tumors.MethodsThe TCGA,GTEx,and GEPIA databases were used to analyze the differences in SIL1 expression between glioma patients and normal controls,and the correlation between their expression and the survival rate of glioma patients was analyzed.The differences in SIL1 expression between the glioma tumor tissues and the paracancerous tissues were examined by immunohistochemistry.In order to explore the function of SIL1 in glioma cells.RNA interference technology was used to knock down the expression of SIL1 in U251 glioma cells.Subsequently,CCK8 assay and plate colony formation assay were used to explore its effect on cell proliferation,revealed by Transwell experiment.Its effect on cell migration and the use of flow cytometry to detect cell cycle and apoptosis.In terms of mechanism,the signal pathways involved in the role of SIL1 in U251 glioma cells play a role through WB.ResultsAnalysis of 163 cases of glioblastoma multiforme and 207 cases of paracancerous tissue,518 cases of low-grade glioma and 207 cases of paracancerous tissue in the TCGA database revealed that compared with paracancerous tissues,The expression rate of SIL1 was significantly up-regulated in GMB and LGG cancer tissues,suggesting that SIL1 is highly expressed in gliomas.Immunohistochemistry detected the expression of SIL1 in 38 clinical glioma tissues and normal adjacent tissues.The results were consistent with the results obtained from the database analysis.SIL1 was hardly expressed in paracancerous tissues and was found in glioma tissues.The expression in the medium was significantly higher than that in the paracancerous tissue.And the expression of SIL1 in grade IV glioma tissue was significantly higher than that in grade Ⅰ-Ⅲ tissue(P=0.026),but not related to age and sex.It indicates that SIL1 is highly expressed in gliomas and is closely related to the progression of tumors and may become a future therapeutic target.In GMB and LGG,patients with high expression of SIL1 have a significant poor prognosis compared with patients with low expression of SIL1.The results of CCK8 showed that the proliferation ability of U251 cell line with stable knockdown of SIL1 was significantly inhibited.Plate clones also showed a significant decrease in cell colony forming ability after interference with SIL1 expression.Transwell assay was used to detect the migration ability of SIL1 knockdown U251 cell line and found that its migration ability was significantly inhibited.Interfering with the expression of SIL1 in U251 can induce apoptosis of cells without affecting the cell cycle.It was also found that the expression of activated Caspase3 and Bax in siSIL1 cell line was significantly increased.After inhibiting the expression of SIL1,the phosphorylation levels of AKT and mTOR protein were significantly reduced,but the protein level was not affected.And the expression of its downstream influence factor p70S6K was also significantly inhibited.It is suggested that SIL1 participates in the AKT signaling pathway and influences the growth and migration of glioma cells.ConclusionSIL1 is highly expressed in gliomas and is closely related to the poor prognosis of glioma patients.SIL1 exerts an oncogene role in gliomas through the AKT/mTOR signaling pathway.Knockdown of SIL1 can inhibit the proliferation and migration of glioma cells U251 and promote apoptosis.It may provide new ideas for the future treatment and prognosis of gliomas. |
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