The Study Of The Effect And Mechanism Of Histone Acetyltransferase MYST1 On Proliferation And Migration Of Human Breast Cancer Cells

Since the 20 th century,cancer has become one of the main threats to human life,and breast cancer has become the most important disease threatening women's life safety.According to statistics,the incidence of breast cancer in the world is increasing year by year,which makes women's physical and mental health greatly threatened.Therefore,it is of great significance to the world to study the pathogenesis of breast cancer and to obtain more effective treatments.In recent years,more and more reports have shown that the occurrence,development and metastasis of breast cancer are closely related to the imbalance of the expression of many tumor-related genes,and epigenetics can clarify how the genetic control of cell division becomes dysfunctional and leads to cancer.This provides the possibility of exploring the mechanism of breast cancer development based on epigenetics and obtaining effective treatment.Acetylation is a unique post-translational modification of proteins in epigenetics.Protein acetylation includes not only histone acetylation but also non-histone acetylation.Among them,non-histone acetylation has been shown to regulate protein function by changing its stability,cell localization and protein-nucleotide,protein-protein interactions,thus regulating the occurrence,development and metastasis of tumors.MYST1,(also known as MOF or KAT8)is an acetyltransferase present in higher eukaryotic cells and consists of a chromatin domain,and an acetyl-CoA binding domain.Previous studies have shown that MYST1 regulates chromatin assembly,transcriptional activation,and apoptosis after DNA damage by acetylating histone H4 lysine 16(H4K16).In addition,the loss of MYST1 in mammalian cells not only reduces histone H4K16 ac,but also leads to abnormal gene transcription,especially to the abnormal expression of certain tumor suppressor genes or oncogenes,indicating that MYST1 plays a key role in tumorigenesis.It has been reported that MYST1 is abnormally expressed in breast cancer,but its molecular mechanism in the occurrence and development of breast cancer has been rarely reported.Therefore,the study of MYST1 and its potential downstream target proteins is of great significance for understanding the molecular mechanism of breast cancer development and developing potential therapeutic targets for breast cancer.This study focused on the molecular mechanism of MYST1 gene regulating the development of breast cancer by regulating USP39 acetylation.The relevant experimental content and results are as follows: 1.MYST1 gene is generally low expression in breast cancerGene Expression Profiling Interactive Analysis(GEPIA)was used to analyze the expression of MYST1 in breast cancer.The results indicate that MYST1 is generally low expressed in breast cancer and is relatively low in most cancers,suggesting that MYST1 may be a cancer-related gene.2.MYST1 interacts with USP39 and co-localized in the nucleusCo-immunocoprecipitation experiments showed that there was protein interaction between MYST1 and USP39,and the interaction between MYST1 and USP39 was mainly mediated by the C-terminal of MYST1 with HAT domain and the N-terminal of USP39 with zinc finger domain.Then we found that MYST1 and USP39 co-localized in the nucleus of human breast cancer cell MCF-7 by immunofluorescence assay.3.MYST1 regulates the acetylation of USP39After determining the interaction between MYST1 and USP39,we further validated the effect of the interaction between MYST1 and USP39 on USP39.Through co-immunoprecipitation assay,we found that overexpression of MYST1 could regulate the acetylation level of USP39,moreover,the protein level of endogenous USP39 increased in breast cancer MCF-7 cell line with stable knockdown of MYST1,indicating that the acetylation of USP39 by MYST1 may affect the protein level of USP39.4.MYST1 knockdown promotes proliferation and migration of breast cancer cellsTo investigate the effect of MYST1 and USP39 on the development of breast cancer,we constructed MYST1 and USP39 stable knockdown and stable overexpression cell lines in human breast cancer cell MCF-7.Then,MTS experiments,colony formation experiments and wound healing assays were performed to examine the proliferation ability and migration ability of each cell line.The results showed that MYST1 knockdown enhanced the proliferation and migration of breast cancer MCF-7 cell line,and USP39 knockdown inhibited the proliferation and migration of breast cancer MCF-7 cell line.Combined with the previous results,we speculated that MYST1 may affect the protein level of USP39 by mediating the acetylation of USP39,thus affecting the proliferation and migration ability of breast cancer.