Objective:The function of euchromatic histone-lysine N-methyltransferase 2(EHMT2)has been studied in several cancers;however,little is known about its role in mantle cell lymphoma(MCL).Thus,this study aimed to characterize the significance and function of EHMT2 in MCL.Methods:EHMT2 expression in MCL and reactive hyperplasia(RH)were investigated by immunohistochemistry.Genome-wide analysis of DNA methylation was performed on EHMT2+MCL samples.The function of EHMT2 was determined by CCK&flow cytometry,and western blot assays.Gene expression profile analysis was performed before and after EHMT2 knockdown to search for EHMT2-regulated genes.Co-immunoprecipitation(Co-IP)experiments were conducted to identify the proteins interacting with EHMT2.Results:EHMT2 was expressed in 68.57%(24/35)of MCLs but not in any RHs.Genome-wide analysis of DNA methylation on EHMT2+MCLs revealed that multiple members of the HOX,FOX,PAX,SOX,and CDX families were hypermethylated or hypomethylated in EHMT2+MCLs.BIX0I294,a EHMT2 inhibitor,inhibited MCL cell growth and stalled cells in the G1 phase.Additionally,BIX01294 downregulated the expressions of cell cycle proteins,cyclin DI,CDK4,and P21,but upregulated the expressions of apoptosis-related proteins,Bax and caspase-3.Co-IP experiments revealed that EHMT2 interacted with UHRF1,HDAC1,and HDAC2 but not with HDCA3.After EHMT2 knockdown,multiple genes were regulated,including CD5 and CCND1,mostly enriched in the Tec kinase signaling pathway.In addition,several genes(e.g.,MARCH 1,CCDC50,HIP1,and WNT3)were aberrantly methylated in EHMT2+MCLs.Conclusions:For the first time,we determined the significance of EHMT2 in MCL and identified potential EHMT2-regulated genes.
Jun WangHui XuShuang GeChaoshuai XueHailing LiXiaotong JingKe LiangXiaoying ZhangCuijuan Zhang
目的探讨5-Aza-dC和TSA对肝细胞癌(hepatocellular carcinoma,HCC)细胞中3-OST-2甲基化水平、基因表达以及对核转录因子UHRF1(ubiquitin-like with PHD and ring finger domains 1,也称为ICBP90/NP95)表达的影响。方法采用甲基化特异性PCR(methylation specific PCR,MSP)法检测药物作用前后HCC细胞株中3-OST-2甲基化的状态改变;采用实时荧光定量RT-PCR法检测3-OST-2和UHRF1 mRNA的表达变化;采用细胞爬片免疫组化法检测UHRF1蛋白表达。结果 3-OST-2在HCC细胞株中呈完全甲基化状态,5-Aza-dC或TSA均能部分逆转3-OST-2甲基化,其mRNA表达分别增加2.7倍和4.9倍,两种药物联合处理后,3-OST-2甲基化被完全逆转,其mRNA表达增加9.1倍。5-Aza-dC或TSA均能降低UHRF1 mRNA和蛋白的表达,TSA比5-Aza-dC疗效更好(P<0.01),两种药物联用具有协同作用(P<0.01)。结论启动子甲基化和组蛋白修饰共同导致3-OST-2基因表达降低。5-Aza-dC和TSA单独作用均能部分逆转3-OST-2甲基化,增加其mRNA表达,抑制核蛋白UHRF1表达可能是其中机制之一。
