The Role And Pathogenesis Of Histone Methyltransferase SMYD3 In Epithelial Ovarian Cancer Metastasis

Research background: Dysregulation of histone lysine methylation and demethylation enzymes frequently occurs in neoplastic diseases.Accordingly,SET and MYND domain containing 3(SMYD3)is a new histone lysine methyltransferase,which has an important role in tumor development by regulating tumor cells’ proliferation and metastasis.However,there is a lack of studies on expression and function of SMYD3 in ovarian cancer,which is worth of a preliminary investigation in this research.Research aim: this research aims to explore the expression of SMYD3 in different samples of ovarian tissue,and examine its influence on,and mechanism of,the metastatic potential of ovarian cancer cell strains.Research methods: this research analyzed the expression of SMYD3 in different samples of ovarian tissue,and its relationship with the clinical characteristic and prognosis of ovarian cancer patients,on the basis of immunohistochemical method.In this research,Western blot and q RT-PCR were employed to examine the expression of SMYD3 in different types of ovarian tissue cell lines,of which the cell lines at low level of expression were used to constructed stable exogenous SMYD3 overexpression cell line,whilst the cell lines at high level of expression were used to constructed stable interfere SMYD3 expression cell line.Furthermore,SKOV-3 cell lines were used to construct not only the overexpression of SMYD3 but also the interference cell lines.The change in the metastatic potential of ovarian cancer cell strains is tested by Transwell chamber experiment.IP/MS is an instrumental method to examine the protein that has interaction with SMYD3,through which p53 is selected,and its interaction with SMYD3 is proved by IP and laser confocal microscopy,respectively.On the basis of the structural domain of SMYD3 and p53,then,this study constructed the truncations of SMYD3 and p53 and find out the part of the structural domain that plays a crucial role in the interactive relationship.Western blot examines the changes of p53,p21,E-Cadherin,N-Cadherin in disturbed or overexpressed cell lines.By transfecting the p53 plasmid and gradually increasing doses SMYD3 plasmid,this research explores whether SMYD3 is dose-dependent of degrading p53.By adding CHX(1mg/m1)in SKOV-3 stable interference groups,over expression groups and control groups,this research observed the influence of SMYD3 on the protein degradation half-life of p53.On the basis of the p53 immunohistochemical scores provided by pathology department,the analysis of the relationship between the expression of p53 and SMYD3 in ovarian cancer samples can be achievable.Findings: in epithelial ovarian cancer,the expression of SMYD3 gradually increased in normal control groups,primary ovarian tumors,and metastatic lesions.In 113 cases of EOC patient,SMYD3 has a substantial correlation with metastasis of ovarian cancer cells,volume of ascites,and FIGO stage.The research findings revealed that the patients with high level of SMYD3 expression have poorer OS and PFS.In ovarian cancer cell lines,the expression of SMYD3 is higher than IOSE cell line,and SMYD3 could accelerate the metastasis of ovarian cancer cells according to the regulation of SMYD3 protein level in the interference and expression groups.The results of IP/MS revealed that there is an interaction between SMYD3 and p53.The results of laser confocal microscopy indicated a spatial colocalization between two,whilst the results of Western blot and q RT-PCR showed that SMYD3 could accelerate nuclear export and degradation of p53 protein and induce EMT of ovarian cancer cells,without affecting p53 transcription.According to the structural domains that construct truncations of SMYD3 and p53,this research testified that the structural domains that have a vital role in the interactive process are the post-SET structural domain of SMYD3 and the DBD structural domain of p53.The experimental study on the fusion of fluorescin with target genes showed that SMYD3 could accelerate the deficiency of p53 nuclear export and degradation when DBD structural domain is lacked.In the ovarian cancer tissue samples,further analysis of SMYD3 and p53 immunohistochemical scores revealed that there is a contrary tendency between these two elements.Conclusions: in the epithelial ovarian cancer,higher expression of SMYD3 may accelerate the degradation of p53 and,consequently,induce the occurrence of EMT in ovarian cancer cells,which may increase the metastatic potential of ovarian cancer cells.