SND1 Affects The Phenotype Of Breast Cancer Cells By Regulating The Expression Of E-cadherin

Objective: Breast cancer is one of the high-risk cancers in the female population,which seriously endangers the health of women in the world.Invasion and metastasis of breast cancer cells are important characteristics of malignant biological behavior of breast cancer,and are also the main factors leading to poor prognosis of patients with breast cancer.The transition of epithelial cells to mesenchymal cells is called epithelial-mesenchymal transformation(EMT).During this process,the adhesion molecules expressed by cells change,which makes the cells prone to metastasis and invasion.Tumor growth and metastasis depend on the development of the tumor's own vascular network,Most malignant,active tumors have significant tumor angiogenesis.Vasculogenic mimicry enables tumor cells to obtain nutrients and growth factors to support the subsequent growth of tumor cells and facilitate the metastasis of tumor cells.EMT and VM are important factors affecting the occurrence and metastasis of breast cancer.Therefore,the effective inhibition of EMT and VM is of great significance in preventing the metastasis of breast cancer cells and improving the survival rate and prognosis of breast cancer patients.The abnormal elevation of SND1 is closely related to the survival rate of the tumor patients.Although the correlation between SND1 and breast cancer progression has been basically clear,there are still many blanks to be added to the specific molecular mechanism of breast cancer in the high level of SND1 on breast cancer progression.Therefore,the purpose of this experiment is to explore how SND1 regulates the epithelial mesenchymal transition and vasculogenic mimicry of breast cancer cells,and then affects the molecular mechanism of breast cancer metastasis.Methods:1.The lentivirus system was used to construct a cell line with stable knockout of SND1 protein in MDA-MB-231 cells,and Western-Blot q-PCR was used to detect the knockout efficiency.2.In vitro phenotypic experiments were used to detect the changes of cell proliferation,invasion,migration and the ability of vascular mimicry in wild type and SND1 knockout cell lines.3 Western-Blot and q-PCR were used to detect the changes in the level of m RNA and protein of marker molecules associated with EMT and VM.4.MDA-MB-231 cells were treated with 5-aza to detect the expression of E-cadherin protein,and the methylation of E-cadherin promoter was detected by Me DIP and BSP.5.Western-Blot and q-PCR were used to detect the changes in the level of m RNA and protein of DNA methyltransferase.6.Ch IP and promoter reporter assay were performed to detect the transcriptional regulation of DNMT3 A by SND1.Results:1.The cell line MDA-MB-231-SND1-sh was successfully constructed in MDA-MB-231 cells,and the level of SND1 in protein and m RNA was significantly reduced.2.The proliferation,invasion,migration and vasculogenic ability of the cell lines with low SND1 decreased significantly than the wild type.3.The E-cadherin protein and mRNA levels were significantly increased in SND1 knockdown cell lines,with the obvious protein down-regulation of mesenchymal phenotype marker N-cadherin and a slight decreased expression of vasculogenic mimicry associated VE-cadherin protein,compared with wild-type cell lines.4.The expression of E-cadherin was reexpressed MDA-MB-231 cell lines after 5-aza treatment,and the methylation of E-cadherin promoter in SND1 knockdown cell lines was significantly reduced compared with wild-type cell lines.5.The DNMT3 B and DNMT1 did not change significantly at the protein level in SND1 knockdown cell lines,while the DNMT3 A protein and m RNA levels were significantly decreased,compared with wild-type cell lines.6.In MDA-MB-231 cells,SND1 can bind to DNMT3 A promoter to activate the expression of DNMT3 A,further promoting the E-cadherin promoter hypermethylation and inhibiting E-cadherin expression.