MiR-409-5p Targets RSU1 Gene And Has A Tumour Suppressive Effect In Breast Cancer

INTRODUCTION:Breast cancer(BC),the most common form of cancer in female patients,is the main cause of cancer death in young and middle-aged patients,and other developed countries such as China and the United States.The Breast cancer carcinogenesis,maturation and metastasis of the potential molecular mechanisms of research is essential.mi RNA has been shown to play a key role in the regulation of the pathogenesis of human breast cancer,chemical pharmacology,cancer development and cancer cell apoptosis [3-5].Such as mi R-31,which inhibits the migration and invasion of triple-negative breast cancer by inhibiting the downstream target gene of SATB2 [6].mi R-409-3p is a member of the human mature micro RNA-409(mi R-409)family and is shown to be highly expressed in plasma of breast cancer patients [7-8].Studies have shown that mi R-409-3p is abnormally downregulated in breast cancer in breast cancer patients;mi R-409-5p has also been reported to be negatively correlated with breast cancer specific survival [9].What is the exact expression profile of mi R-409-5p and its mechanism of action in breast cancer has not been elucidated.Human Ras inhibitory protein 1(RSU1)gene has a cytostatic effect in glioblastoma and breast cancer,and whether there is an upstream activator-induced study of the antitumor effect of RSU1 in breast cancer has not been reported.In this study,mi R-409-5p was used to regulate the expression of RSU1,and the relationship between mi R-409-5p expression and breast cancer was studied.OBJECTIVE:To investigate the expression and function of mi R-409-5p in human breast cancer and to evaluate the effect of mi R-409-5p down-regulation on breast cancer proliferation,migration and xenograft development.To investigate the function of RSU1 in human breast cancer cells by sh RNA down-regulating the expression of RSU1,and to further study the effect of micro RNA-409-5p targeting RSU1 gene on breast cancer and its possible molecular mechanism.For the future diagnosis and treatment of breast cancer to provide the basis.METHODS:qRT-PCR was used to evaluate the expression of endogenous mi R-409-5p in breast and breast cancer cell lines.The mi R-409-5p in the breast cancer cell lines MDA-MB-231 and MCF-7 cells was down-regulated by lentiviral transfection experiments to evaluate the effect of mi R-409-5p down-regulation on breast cancer proliferation,migration and xenograft development Impact.The gene expression levels of Ras inhibitory protein 1(RSU1)of mi R-409-5p downstream of lentivirus-mediated mammary gland cells were detected by q RT-PCR and protein immunoblotting by double luciferase activity assay.RSU1 was inhibited in mi R-409-5p down-regulated breast cancer cells to investigate its effect on mammary gland proliferation and migration.The expression of RSU1 in breast cancer cells was down-regulated by sh RSU1.The effect of RSU1 knockdown on the proliferation,cell cycle and apoptosis of human breast cancer cells was evaluated by real-time PCR.RESULT:The expression of mi R-409-5p in breast cancer tissue was higher than that in normal breast tissue by q RT-PCR and western blottig experiments.The expression of mi R-409-5p in human breast cancer cell line MCF-7,MDA-MB-231 cells were higher than that of human normal breast cells MCF10 A cells;RSU1 protein in human breast cancer and breast cancer cells were lower than the normal expression of normal tissue or normal breast cells.The expression of endogenous mi R-409-5p in breast cancer cell lines MDA-MB-231 and MCF-7 cells was down-regulated by lentivirus transfection.The expression of mi R-409-5p down-regulated breast cancer cell line MDA-MB-231 and MCF-7 cells were significantly inhibited in vitro,significantly reduced the migration of cancer cells and reduced the metastasis of breast cancer.At the same time,down-regulation of mi R-409-5p expression significantly inhibited the migration of MDA-MB-231 xenografts in nude mice,and L/mi R409 I transfected tumor was significantly reduced compared with L/i transfected tumor.The results showed that RSU-1 was the downstream target gene of mi R-409-5p in breast cancer cells,and the expression of RSU1 in L/mi R409 i transfected cancer cells was significantly up-regulated.Western blot analysis showed that RSU1 RSU1 protein levels also showed similar results.The results of q RT-PCR showed that the expression level of endogenous RSU1 in MDA-MB-231 and MCF7 cells transfected with L/mi R409 I was significantly down-regulated by Si-RSU1.Western blot analysis showed that L/mi R409 I transfected MDA-231 and MCF7 cells were significantly down-regulated by Si-RSU1.The proliferation of MDA/MB-231 and MCF7 cells transfected with L/mi R409 I was significantly increased after RSU1 down-regulation,and the down-regulation of RSU1 significantly promoted L/mi R409 I Transfection of metastatic breast cancer cells.CONCLUSION:The expression of mi R-409-5p in human breast cancer and two kinds of human breast cancer cell lines was significantly increased,and RSU1 expression was significantly down-regulated in human breast cancer tissues and cells.Studies have shown that downregulation of breast cancer cell mi R-409-5p can inhibit tumorigenesis by inhibiting its in vitro proliferation and migration.mi R-409-5p is down-regulated in the development of breast cancer,and the down-regulation of RSU1 expression has the opposite effect,which can reverse the effect of reversing its inhibitory effect on proliferation and migration of breast cancer in vitro.