Prognostic Value Of H3K79 Methyltransferase Disruptor Of Telomeric Silencing-1-like (DOT1L) Expression In Patients With Ovarian Cancer And The Mechanism Of Dissemination And Metastasis Of Ovarian Cancer

Background:Epigenetics has been known to play a critical role in regulating the malignant phenotype.This study was designed to examine the expression of DOT1L(histone 3 lysine 79 methyltransferase)and H3K79 methylation in normal ovarian tissues and ovarian tumors and to explore the function of DOT1L and its underline mechanisms in ovarian cancer.Methods:The expression of DOT1L and H3K79 methylation in 250 ovarian tumor samples,24 normal ovarian samples and paired primary and metastatic tissues of ovarian cancer was assessed by immunohistochemistry.The effects of DOT1L on cancer cell metastasis in vitro were evaluated using Transwell assay,scratch assay,adhesion assay and FITC-Dextran Transwell assay.The possible mechanism of ovarian cancer metastasis mediated by DOT1L was determined using cDNA microarray,ChIP-seq and bioinformatics analysis.Gene expression levels were measured by real-time PCR and immunoblotting.The effects of DOT1L on tumor metastasi in vivo were evaluated using an orthotopic ovarian tumor model,short-term lung colonization assay and experimental lung metastasis study.Results:DOT1L expression and H3K79 methylation was significantly increased in malignant ovarian tumors and metastatic tissues.High DOT1L expression was associated with FIGO stage,histologic grade,and lymphatic metastasis.DOT1L was an independent prognostic factor for the overall survival(OS)and progression-free survival(PFS)of ovarian cancer,and higher DOT1L expression was associated with poorer OS and PFS.DOT1L could promote ovarian cancer cell migration,invasion,adhesion and vascular permeability.DOT1L participates various process of ovarian cancer metastasis mediated by DOTIL-targetd gene SPARC,such as extracellular matrix-receptor combination,tumor cell adhesion and endothelial cell migration.Moreover,DOT1L regulates the transcription of SPARC through H3K79 methylation.Furthermore,in vivo experiment verified that DOT1L could promote ovarian cancer both in peritoneal metastasis and hematogenous metastasis.Given that small molecular inhibit SGC0946 could attenuate ovarian cancer metastasis in an orthotopic ovarian tumor model,DOT1L can be identified as a promising target for ovarian cancer metastasis therapy.Conclusions:Our findings first demonstrate that DOT1L over-expression has important clinical significance in ovarian cancer and also clarify that it drives progression of ovarian cancer metastsis through transcriptional regulation of SPRAC through H3K79 methylation,suggesting that DOT1L might be potential target for prognostic assessment and therapeutic intervention in ovarian cancer.