Molecular Mechanism Of HER2/ELK1 Signal Axis Promoting Meningioma Proliferation By Regulating LUC7L3 Expression

Objective:In this study,we studied the expression of LUC7L3,HER2 and ELK1 in meningiomas to explore the possible molecular mechanism of HER2/ELK1/ LUC7L3 signal axis promoting meningioma proliferation.Methods:1.In malignant meningioma IOMM-Lee cell line,lentivirus transfection interfered with and overexpressed LUC7L3 gene,which was divided into five groups:1)blank control group(Blank);2)interfering with LUC7L3 group(LUC7L3-sh);3)overexpressing LUC7L3 group(LUC7L3-ox);4)interfering unrelated sequence group(NC-sh);5)overexpressing unrelated sequence group(NC-ox).The m RNA expression levels of HER2,ELK1 and LUC7L3 in each group were detected by q-PCR method.2.In the experiment of tumor formation in nude mice,the growth-time curve of malignant meningioma IOMM-Lee cell line was drawn,the tumor inhibition rate was calculated,and the protein expression of LUC7L3 and Ki-67 in each group was detected by immunohistochemistry and Western blot.3.After HER2 inhibitor Lapatinib(GW-572016)was used to interfere with IOMM-Lee of malignant meningioma,q-PCR and Western blot were used to detect the m RNA and protein expression of HER2,ELK1,p-ELK1 and LUC7L3,respectively.4.Double fluorescein plum report detection and chromatin immunoprecipitation assay to verify the binding between LUC7L3 promoter and transcription factor ELK1,and to find specific binding sites.5.The expression levels of HER2 and LUC7L3 in 70 paraffin-embedded meningiomas and 5 normal arachnoid tissues were detected by immunohistochemical method to verify the correlation between HER2 and LUC7L3.Results:1.After interfering with and overexpressing malignant meningioma IOMM-Lee cell line LUC7L3,the m RNA expression levels of HER2,ELK1 and LUC7L3 in each group were detected by q-PCR method: the expression level decreased by about42.2% in the interference group and increased by about 51.4% in the overexpression group,which met the requirements of experimental grouping.2.In the experiment of tumorigenesis in nude mice,compared with the blank control group,the tumorigenesis ability of nude mice in LUC7L3-sh group was weakened,and the rate of tumor proliferation slowed down.The results of,Western Blot and immunohistochemistry showed that the expression levels of LUC7L3 and Ki-67 were significantly decreased,while the tumorigenesis ability,tumor proliferation and migration ability of nude mice in LUC7L3-ox group were enhanced.The results of,Western Blot and immunohistochemical staining showed that the expression levels of LUC7L3 and Ki-67 were significantly increased.3.After HER2 inhibitor Lapatinib(GW-572016)was used to interfere with malignant meningioma IOMM-Lee,the m RNA expression of HER2 and LUC7L3 in malignant meningioma cell line IOMM-Lee decreased by 56.5 ± 7%.The m RNA expression of m RNA decreased by 43±6%,and the protein expression of P-ELK1 and LUC7L3 decreased by 73.4±6%.The protein expression of ELK1 decreased by10±2%.4.The results of software prediction analysis showed that there were 15 binding sites of transcription factor ELK1 in the promoter region of LUC7L3 gene.The results of double luciferase reporter gene and chromatin immunoprecipitation assay confirmed that the transcription factor ELK1 could specifically bind to the promoter region of LUC7L3 and had two stable binding sites.5.Immunohistochemical method was used to detect the protein expression of HER2 and LUC7L3 in normal arachnoid tissue and different grades of meningioma.The results showed that the higher the malignant degree of meningioma was,the stronger the expression of HER2 protein was.There was also a certain expression of LUC7L3 in normal arachnoid tissue,and there was no significant difference between the expression of LUC7L3 protein and the degree of malignancy.The expression of HER2 was positively correlated with the expression of LUC7L3.Conclusion:1.There is a correlation between HER2/ELK1 signal axis and LUC7L3 in malignant meningioma IOMM-Lee cell line,and LUC7L3 is the downstream target gene of HER2/ELK1 signal axis.2.In meningioma tissue,HER2 may be related to the malignant degree of meningioma,but LUC7L3 has no correlation with the malignant degree of meningioma.