The Mechanism Of Methyl Transferase SETD7 With Hepatocellular Carcinoma And The Correlation With Its Prognosis

Hepatocellular carcinoma(HCC)is one of the most common malignant tumors worldwide.In China,HCC is the third leading cause of morbidity and the second leading cause of mortality among malignancies,with a total mortality rate of 26.26 per 100,000.The cause of HCC is multifaceted,that is,complex genome and epigenetic alterations,including changes in histone modification,DNA methylation,abnormal micro RNA expression,and epigenetic regulation of the altered gene expression,which are all correlated with the development and progression of HCC.Histone 3 lysine 4(H3K4)specific histone methyltransferases(HMTs)catalyze H3K4 methylation,which is generally associated with gene activation.Dysregulated expression of H3K4 HMTs and their genetic mutations lead to malignant progression.Lysine methyltransferase SETD7 belongs to the SET domain-containing proteins,can not only demethylation of H3K4(H3K4me2)and promotes downstream gene expression,but also methylation non-histone,which can change the chromatin state by influencing the binding abilities of the cofactor to the histone via direct histone methylation and promotes downstream gene expression.Moreover,SETD7 potentially regulates proteins,modulates transcription factor activity,and activates promoters of methylation-dependent co-recruitment by mediated methylation of non-histone proteins.Reports indicate that SETD7 plays an important role in inflammation,metabolism-associated diseases,viral infection,and oncogenesis.SETD7 controls intestinal regeneration and tumorigenesis,and high expression of SETD7 in ovarian cancer forebode poor prognosis.However,the functions and mechanisms of SETD7 in HCC remain poorly understood.The main purpose of this study is to explore the function and mechanism of SETD7 in the carcinogenesis and development of HCC and the releveance to HCC patients' prognosis.Twenty pairs of HCC samples including HCC tissues and paired ANLTs were surgically collected at the general surgery department.Western blot and QRT-PCR were performed to detect the expression of SETD7 in tissues.SETD7 higher expression in HCC than in ANLTs.225 pairs of paraffin-embedded tissues,including HCC tissues and ANLTs,were obtained into tissue microarrays(TMAs).Clinical data,including patient characteristics,clinical presentation,tumor differentiation,sites of lesion,laboratory findings,objective response,and survival were collected from the hospital information system.IHC assay was performed in TMAs to detecte the expression of SETD7,H3K4me2.Statistical methods were performed to analysis the results combination with clinical data and H3K4me2.It turned out that SETD7 expression was significantly correlated with H3K4me2.Increased SETD7 is associated with metastasis,recurrence,large tumor size,poor tumor differentiation and indicates poor prognosis in HCC patients.To explore the function and mechanism of SETD7 regulate HCC development and progression.SETD7 overexpression plasmid was constructed and transfected into Hep G2 cells,three interference sequences were designed to knockdown SETD7 in SMMC-7721 to explore the function of SETD7 in liver cancer cell lines.To elucidate the underlying target genes and function of SETD7,DGE analysis was performed after SETD7 knockdown in SMMC-7721.The m RNA and protein levels of the target genes that predicted by DGE were subsequently verified by QRT-PCR and Western blot analysis in SETD7 knockdown in SMMC-7721 cells and in SETD7 overexpression in Hep G2 cells.The result indicated that SETD7 exhibited a markedly higher expression in HCC than in ANLT;SETD7 overexpression promoted Hep G2 cell proliferation,whereas SETD7 knockdown inhibited SMMC-7721 cell proliferation by regulating the cell cycle.The expression of SETD7 was associated with the level of ZBTB20 and CDKN2 D.SETD7 is higher expression in HCC than in ANLTs.High expression of SETD7 in HCC is associated with recurrence,metastasis,size(> 5 cm),poor differentiation,H3K4me2 and indicates poor prognosis in HCC patients.SETD7 high expressioned in cells can promote proliferation,and this effect associated with the cell cycle.SETD7 can regulat ZBTB20 and CDKN2 D expression or other cell cycle related signaling pathway to affect the cell cycle.