The Molecular Mechanism Of Core Fucosyltransferase FUT8 In Breast Cancer

Glycosylation is involved in many basic molecular and cell biological processes of cancer.Among them,core fucosylation closely related with progression of various cancers.It is shown that only one glycosyltransferase,fucosyltransferase 8,(FUT8)in charge of core fucosylation.In this thesis,a systematic review and meta-analysis were firstly carried out to clarify the relationship between FUT8 and the clinicopathological characteristics and survival of malignant tumors based on the collection of references and GEO data.Next,we clarified the molecular mechanism of miR-10b regulating FUT8 expression in breast cancer.The main research conclusions are as follows:1.Meta-analysis showed that FUT8 is associated with clinicopathological characteristics of certain malignant tumor types and patient survival rates.First,we systematically identified7 articles and 35 microarray datasets(involving 6124 patients and 10 tumor types)for inclusion in meta-analysis.The results showed that FUT8 expression significantly correlated with one or more clinicopathological parameters including patient gender,molecular subgroup,histological grade,TNM stage,estrogen receptor,progesterone receptor,and recurrence status.Second,FUT8 expression level was associated with overall survival in non-small cell lung cancer,breast cancer,diffuse large B cell lymphoma,gastric cancer,and glioma.FUT8 expression was also correlated with disease-free survival in non-small cell lung cancer,breast cancer,and colorectal cancer,and with relapse-free survival in pancreatic ductal adenocarcinoma.2.Using bioinformatics methods,it was found that the expression of FUT8 in most cancers was significantly up-regulated compared with normal tissues,and the expression of FUT8 in breast cancer was significantly higher than other fucosyltransferases.Next,the results of tissue microarray and clinical sample staining show that the expression of FUT8 in breast cancer tissue is higher than that in normal breast tissue.It is found that overexpression of FUT8 can promote cell migration and the process of EMT,while interference with FUT8 expression can inhibit the proliferation,migration and invasion of cancer cells.3.In vivo and vitro experiments proved that knockdown of FUT8 in MDA-MB-231 cells makes cancer cells more sensitive to adriamycin.Knockdown of FUT8 expression can reduce breast cancer cell proliferation and increase cell apoptosis.The ratio of CD44~+/CD24~-stem cells decreased in FUT8 knockdown MDA-MB-231 cells.Finally,after multiple passages of tumor stem cells into spheroids,it was found that the number of spheroids in FUT8 knockdown MDA-MB-231 was lower than that in normal FUT8 cells,indicating that the expression of FUT8 may affect the self-renewal ability of tumor stem cells.4.It is predicted that AP-2γis the biological target gene of miR-10b.Using the TCGA database and tissue microarray analysis,it was found that AP-2γexpression is low in breast cancer but high in normal breast tissue,which is opposite to the expression of FUT8.The overexpression of AP-2γin MDA-MB-231 cells significantly reduced the proliferation,migration and invasion capabilities of the cells.In vivo study,it was found that overexpression of AP-2γcan inhibit the expression of FUT8 in breast cancer cells,and can also inhibit tumor growth and metastasis.The luciferase reporter gene indicated that miR-10b can directly bind to the 3’UTR region of AP-2γand inhibit the expression of AP-2γ.5.It is predicted by Pathway Commons that AP-2γcan indirectly regulate FUT8 through STAT3/p-STAT3.After AP-2γwas overexpressed,the expression of FUT8 and p-STAT3decreased significantly;It is also shown the expression of FUT8 decreased with lower expression of phosphorylation level of STAT3 in breast cancer cells The Co-IP result found the binding affinity between AP-2γand STAT3 was stronger than the binding affinity between AP-2γand p-STAT3.Ch IP data showed that p-STAT3 can bind to FUT8 promoter region.We propoased a novel regulatory pathway of miR-10b/TFAP2C/p-STAT3/FUT8 in breast cancer,which can affect the proliferation and metastasis of breast cancer and provide some theoretical basis for exploring the treatment of breast cancer.