Correlation Between LEF-1 And β-catenin Expression And Clinicopathologic Features In Breast Cancer

Background:As the most common of malignant tumors in women,the incidence of breast cancer is high and increasing,and the age of onset is showing a trend towards a younger age.It is a heavy burden for many patients and their families.Survival rates are somewhat higher if patients are diagnosed and treated early,but the outcome and prognosis for patients with intermediate or advanced disease is very poor.Among the current treatment options,surgery remains the mainstay of treatment,but also carries the risk of recurrence;endocrine therapy can still lead to treatment failure due to drug resistance;radiation therapy and chemotherapy have high adverse reactions,which decrease in quality of life for patients.The research that has been done to find effective drugs and treatment options for breast cancer is not perfect.This shows that study the possible mechanisms of breast cancer formation and the possible therapeutic targets is necessary,to refine treatment options or discover new treatments.LEF-1 and β-catenin are important components of the WNT signaling pathway,are involved in a variety of tumorigenic processes.The oncogenic mechanism of LEF-1 is mainly through its mediated signaling pathway in tumor proliferation,differentiation,invasion and metastasis.The lack of intercellular connectivity is also associated with alterations in the structure and function of β-catenin,which leads to invasive infiltration and metastasis.Several studies have shown that β-catenin and LEF-1 have gene mutations and abnormal protein expression in human breast cancer are important steps in the formation of breast cancer.However,the function of LEF-1 and β-catenin in breast cancer tumor cells and their clinicopathological features has not been clearly investigated.Objective:In this study,we analyzed the expression of LEF-1 and β-catenin in breast cancer tissues based on the public database GEPIA2.In addition,the role of LEF-1 andβ-catenin in the proliferation,migration and invasion of breast cancer was explored in vitro through cellular assays.Meanwhile,the expression of LEF-1 and β-catenin was studied at the tissue level of breast cancer by immunohistochemistry,and the relationship between each and the general clinical profile and pathological features of breast cancer patients was analysed.Methods:1.The expression difference of LEF-1 and β-catenin between breast cancer tissue and normal breast tissue was downloaded from GEPIA2 database.2.Extraction of total RNA from mammary epithelial cells HBL-100 and breast cancer cells MDA-MB-231,T47D,ZR-75-1,MCF-7 and detection of LEF-1 and β-catenin expression by qRT-RCR.3.The small molecule interfering fragment siRNAs of LEF1 and β-catenin were constructed and transfected with MDA-MB-231 and T47D,respectively.qRT-RCR was performed to analyze the expression of LEF1 and β-catenin in MDA-MB-231 and T47D.4.After constructing si-LEF-1 and si-β-catenin in MDA-MB-231 and T47D,several functional experiments(cck-8 assay,cell scratch assay,and transwell assay)were performed to evaluate the role of LEF-1 and β catenin in malignant behavior of breast cancer cells.Analysis of changes in β-catenin expression after down-regulation of LEF-1 and changes in LEF-1 expression after down-regulation of β-catenin using qRT-RCR.In addition,Western Blot assays illustrated changes in the expression of Bcl-2,Bax and Caspase-3 after down-regulation of LEF-1 and β-catenin.5.From December 2019 to December 2020,Sixty cases of breast cancer pathologically diagnosed by the Second Affiliated Hospital of Nanchang University were collected.After immunohistochemical staining,all section specimens were interpreted by two experienced pathologists.Finally,after counting their expression pattern status,the relationship between them and clinicopathological characteristics such as age,tumor size,degree of differentiation and molecular typing was analyzed and the correlation between LEF-1 and β-catenin.Results:1.Analysis in the GEPIA2 database showed that LEF-1 and β-catenin expression levels were significantly upregulated in breast cancer tissues.Higher expression of LEF-1 and β-catenin in breast cancer cell lines than in normal breast epithelial cell lines.2.Lowering the expression levels of LEF-1 and β-catenin in breast cancer cell lines MDA-MB-231 and T47D significantly decreases the proliferation,the migration and the invasive ability of breast cancer cells.3.Western blot assay illustrated that after down-regulating the expression levels of LEF-1 and β-catenin in MDA-MB-231 and T47D,the expression of Bax and Caspase-3 proteins were relatively increased,while the expression of Bcl-2 protein was relatively decreased compared to the si-NC group.4.In the group with tumor size<2 cm,the positive rate of LEF-1 was 25%,while in the tumor size≥2 cm group,the positive rate of LEF-1 was 68.7%,which means that the expression level of LEF-1 increased with the increase of tumor tissue(P<0.05);the positive expression rate of LEF-1 in the group with lymph node metastasis was 78.2%,which was higher than that in the group without lymph node metastasis(P<0.05);the positive expression rate of LEF-The positive expression rate of LEF-1 in lumina,HER2 and triple-negative breast cancer was 64.4%(29/45),11.1%(1/9)and 100%(6/6)respectively;the expression level of LEF-1 in breast cancer was related to tumour size,lymph node metastasis and molecular typing,but not to age,tumour pathological grade and Ki-67 proliferation index.In the tumour size<2cm group,the positive rate of β-catenin was 50%,while in the tumour size≥2cm group,the positive rate of LEF-1 was 87.5%,the larger the tumour tissue,the higher the positive β-catenin expression rate(P<0.05).The expression level of β-catenin in breast cancer was related to the size of the tumour,but not to age,tumour pathological grade and the presence of Ki-67 proliferation index.The expression level of β-catenin in breast cancer was related to tumour size but not to age,tumour grade,lymph node metastasis,Ki-67 proliferation index and molecular typing.Conclusion:1.LEF-1 and β-catenin are highly expressed in breast cancer.2.LEF-1 and β-catenin can promote the proliferation,migration and invasion of breast cancer cells.3.The level of LEF-1 in breast cancer was related to tumor size,lymph node metastasis and molecular typing,but not to age,tumor pathological grade and Ki-67 proliferation index.The level of β-catenin in breast cancer tissues was related to tumor size,but not to age,tumor pathological grade,presence of lymph node metastasis,Ki-67 proliferation index and molecular typing.