| Research background: Breast cancer is a kind of highly heterogeneous malignant tumors,which has many different pathological types.The clinical diagnosis and treatment of different patients have great differences,and the prognosis also shows a variety of results.Triple-negative breast cancer(TNBC)belongs to a class of subtype of triple-negative breast cancer(TNBC),which is characterized by inadequate expression of estrogen receptor(ER),progesterone receptor(PR)and human epidermal growth factor receptor 2(HER-2).The incidence of triple-negative breast cancer in all breast cancer patients ranges from 20% to 25% and is directly related to poor prognosis.Therapies(such as endocrine therapy or trastuzumab)for triple-negative breast cancer patients has not been effective because it lacks proper targeting of these drugs.And after treatment,triple negative breast cancer patients have high recurrence in a short time.It has a high lymph node metastasis rate,strong invasiveness,and a high mortality rate,which will have a serious impact on women's quality of life and safety of life.Therefore,research on the treatment of triple negative breast cancer has become the focus of medical researchers.Epithelial-mesenchymal transformation(EMT)is a key mechanism of tumorigenesis and development,participate in the process of invasion and metastasis of the malignant tumor.Epithelial-mesenchymal transformation is closely associated with the prognosis of triple-negative breast cancer and can identify potential therapeutic targets.Malignant tumors can degrade ECM by proteolysis.A proteolysis system involved in these processes is the uPA system,which consists of uPA,uPAR and uPA inhibitors 1 and 2(PAI-1 and PAI-2).UPA is an extracellular matrix-degrading protease involved in cancer invasion and metastasis.PAI-1 was initially identified as an endogenous quick-acting inhibitor of uPA from blood sources.It is reported that elevated levels of uPA,PAI-1 and uPAR are associated with poor prognosis in triple-negative breast cancer patients.In addition,uPA and PAI-1 may be new prognostic markers for axillary lymph node-negative patients.So far,there is increasing evidence that the uPA system promotes cancer metastasis through several different mechanisms,not just by decomposing ECM.The elevated levels of uPA and PAI-1 in breast cancer tissues are statistically independent and are effective predictors of poor prognosis.In addition to prognosis,high levels of uPA and PAI-1 have been shown to predict the benefits of adjuvant chemotherapy in early breast cancer patients.The unique clinical efficacy of uPA/PAI-1 as a prognostic biomarker for lymph node-negative breast cancer has been confirmed in two independent studies.Therefore,uPA and PAI-1 are the best prognostic biomarkers for triple-negative breast cancer.Objective: This study was to explore the relationship between PAI-1 and the proliferation,invasion and metastasis of TNBC cells by stimulating EMT.The xenotransplantation mouse model and tissue microarray analysis were established to observe the relationship between PAI-1 and tumor growth in vivo.The TCGA database was used to explore the relevance of of the TNBC patients prognosis and PAI-1 expression.Methods: 1.EMT were stimulated on TNBC cell lines and the expression of certain proteins were detected through TMT markers combined with LC-MS /MS,etc.,which verified that EMT could promote the secretion of PAI-1 on TNBC cell lines.2.To investigate effects of PAI-1 on TNBC cell lines,cell counting and cell colony formation assay.3.In order to observe the migration and invasion effects of PAI-1 on TNBC cell lines,transwell,wounding healing assay,western blotting and immunofluorescence were used in our research.4.The model of PAI-1-/-mouse was established.PBS,PAI-1 or PAI-039 were injected around the tumor.The expression of certain proteins were detected by IHC to explore the effect of PAI-1 on tumor growth in vivo.5.PAI-1,E-cadherin and N-cadherin were detected by tissue microarray in 165 TNBC patients.The expression of PAI-1 gene in different molecular subtypes of breast cancer was analyzed in the cancer genome atlas(TCGA)database to explore the relationship between PAI-1 gene expression and prognosis of breast cancer patients.Results: We found that PAI-1 secreted by TNBC could promote cell growth,migration and invasion.Similar results were found in EMT-labeled TNBC cell lines and xenografted PAI-1-/-mice models.By studying tissue microarrays and published breast cancer databases of 165 patients with TNBC,we found that PAI-1 expression in breast cancer was significantly higher than that in normal adjacent tissues,and was associated with the prognosis of patients with TNBC.Conclusion: Our results indicate that PAI-1 plays an important role in the EMT process of TNBC cells,and suggest that the development of PAI-1 targeted therapy for clinical TNBC patients has great potential. |
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