MicroRNA-188-5p Inhibits The Progression Of Triple Negative Breast Cancer Through Targeting Zinc Finger Protein 91

Objective:Breast cancer(BC)is one of the most common malignancy in the world,which mortality rate ranks first among female malignant tumors.Globally,the number of newly diagnosed BC cases reached about 2.1 million in 2018,accounting for almost 25%of cancer cases among women.BC performs a complex pathogenesis and is a clinically heterogeneous disease with a wide range of clinical behaviors and treatment responses.Although many dysregulated molecular pathways have been discovered in BC,the development of therapeutic methods has been limited.It is urgent to discover novel molecules to suppress BC proliferation,induce apoptosis and inhibit invasion,and provide potential therapeutic strategies to improve the survival and quality of life of patients.MicroRNAs(miRNAs)are a class of endogenous non-coding RNAs of approximately 19-24 nucleotides in length,which are generally located in unstable regions of human genome and usually dysregulated in malignant tumors to regulate gene functions.miRNAs perform an key role in differenttumor cellular processes including proliferation,cell cycle,apoptosis,invasion and metastasis,and participate in almost all signaling pathways.Highly expressed proto-oncogene miRNAs in malignant tumors promote tumor formation through targeted binding of tumor suppressor genes to regulate gene expression,while low-expressed tumor suppressor gene miRNAs can suppress the original Oncogenes and control cell differentiation and growth to control tumor formation.Previous studies have shown that miR-188-5p plays a role of tumor suppressor gene in gastric cancer,prostate cancer,liver cancer,and acute myeloid leukemia.It suggests that miR-188-5p may be a general tumor marker,making it a promising target for drug development.However,the role of miR-188-5p in breast cancer remains unclear.It is therefore of great importance to study the effects and mechanisms of miR-188-5p on the invasion,proliferationand apoptosis of human breast cancer cells.In this study,by detecting the expression of miR-188-5p in breast cancer tissues and cells,the relationship between the expression of miR-188-5p and its clinicopathological properties and prognoses was analyzed.Use of bioinformatics to predict and analyze the downstream target protein miR-188-5p and ZFP91,and use the dual luciferase reporter system to verify.Through a series of in vitro cell experiments and in vivo animal experiments,our aim is to explore the effects and mechanisms of miR-188-5p targeting ZFP91 in regulating breast cancer proliferation,apoptosis,invasion and metastasis and EMT mechanisms,suggesting that miR-188-5p may be a promising target for the treatment of breast cancer in the future.Methods:1.The expression levels of miR-188-5p in 50 ovarian breast cancer tissues and50 normal ovarian tissues were analyzed by qRT-PCR.2.The expression levels of miR-188-5p in four human breast cancer cell lines(MDA-MB-231,BT-549,MCF-7)and one human normal breast epithelial cell(MCF-10A)were analyzed by qRT-PCR.3.The function of miR-188-5p in human breast cancer cells was studied by transfection,CCK-8experiment,flow cytometry and transwell after over-expressing miR-188-5p.4.The expression levels of ZFP91 in breast cancer tissues and breast cancer cell lines were analyzed by qRT-PCR and western blot.The relationship between miR-188-5p and ZFP91 was confirmed by luciferase assay.5.The mechanism of miR-188-5p and ZFP91in breast cancer proliferation,apoptosis,invasion and metastasis were explored by transfection,CCK-8 experiment,flow cytometry,transwell and wester blot.Results:1.Compared with adjacent tissues,the expression level of miR-188-5p in breast tissues is down-regulated,and the expression is the lowest in stage IV,indicating that the down-regulation of miR-188-5p is significantly related to advanced TNM.2.Compared with MCF-10A,the expression level of miR-188-5p in the other three breast cancer cell lines(MDA-MB-231,BT-549,MCF-7)is down-regulated,interestingly,the expression of miR-188-5p in MDA-MB-231 was the lowest level.3.Overexpression of miR-188-5p could significantly inhibit the proliferation of MDA-MB-231 cells,promotes cell apoptosis,and reduces cell invasion and migration.4.The expression of miR-188-5p in BC is negatively related with ZFP91,miR-188-5p regulates the proliferation,invasion and apoptosis of breast cancer cells by targeting ZFP91.ZFP91 was predicted and confirmed as a target gene of miRNA-188-5p,and the effects of miR-188-5p on breast cancer cells were dependent on the inhibition of ZFP91.5.A decrease in ZFP91significantly inhibited the NF-?B p65 and Rel B expression in breast cancer cells.Therefore,miR-188-5p can inhibit breast cancer progression via the ZFP91/NF-?B/p65axis and may be a potential diagnostic indicator for breast cancer.Conclusion:1.The expression of miR-188-5p is downregulated in breast cancer tissues or breast cancer cell lines.2.Overexpressed miR-188-5p can significantly inhibit the proliferation of breast cancer cells,promote cell apoptosis,reduce cell invasion and migration,and act as tumor suppressor genes.3.ZFP91 is upregulated in breast cancer tissues and breast cancer cell lines.It is negatively correlated with the expression of miR-188-5p in breast cancer.Restoration of ZFP91 largely reversed the decreased proliferation and induced apoptosis which were both regulated by miR-188-5p overexpression.4.miR-188-5p can inhibit breast cancer progression via the ZFP91/NF-?B/p65 axis and maybe a potential diagnostic indicator for breast cancer.