METTL14介导ERα的m6A修饰调控子宫内膜癌转移的机制研究

Mechanism of METTL14-mediated ERαm6A regulation of endometrial cancer metastasis

背景与目的:甲基转移酶样因子14(methyltransferase-like factor 14,METTL14)失调引起的异常N6-甲基腺苷(N6-methyladenosine,m6A)修饰在多种癌症的进展中发挥重要作用,目前尚不清楚其是否参与子宫内膜癌(endometrial cancer,EC)的进展。本研究旨在探讨METTL14失调引起的异常m6A修饰在EC侵袭和转移中的作用。方法:收集96例2017—2021年在青海省人民医院接受治疗性手术的EC患者。从冷冻组织中分离RNA(70对)或蛋白质(10对),用于实时荧光定量聚合酶链反应(real-time fluorescence quantitative polymerase chain reaction,RTFQ-PCR)或免疫印迹分析,以评估METTL14在EC中的表达。评估METTL14的表达及其与EC临床病理学特征的相关性。在体外和体内测定METTL14在EC中的生物学效应。将甲基化RNA免疫沉淀测序(methylated RNA immunoprecipitation sequencing,MeRIP-seq)与RNA测序(RNA sequencing,RNA-seq)相结合,并在m6A斑点印迹后,采用MeRIP-RTFQ-PCR、RIP-RTFQ-PCR或双荧光素酶报告基因分析来筛选和验证METTL14的候选靶标。结果:与匹配的相邻组织相比,EC中METTL14的mRNA表达和蛋白质水平显著下调。与METTL14高表达组相比,METTL14低表达组国际妇产科联盟(International Federation of Gynecology and Obstetrics,FIGO)分期、浸入深度、淋巴管血管侵犯、淋巴结转移及肿瘤转移例数显著增加(P<0.05)。在功能上,METTL14在体外和体内抑制EC细胞的增殖和侵袭能力。从机制上讲,METTL14介导的m6A去甲基化导致雌激素受体α(estrogen receptor alpha,ERα)转录后抑制。此外,与METTL14相比,ERα诱导肿瘤的致癌行为。结论:METTL14通过m6A依赖性方式在EC细胞中减弱ERα的表达,进而抑制肿瘤转移和侵袭。

Background and purpose:Aberrant N6-methyladenosine(m6A)modification caused by dysregulation of methyltransferase-like factor 14(METTL14)plays an important role in the progression of various cancers,and it is unclear whether it is involved in the endometrial cancer(EC)progression.This study aimed to investigate the role of aberrant m6A modification caused by dysregulation of METTL14 in EC invasion and metastasis.Methods:Ninety-six EC patients who underwent curative surgery in Qinghai Provincial People’s Hospital from 2017 to 2021 were enrolled.RNA(70 pairs)or proteins(10 pairs)were isolated from frozen tissues for real-time fluorescence quantitative polymerase chain reaction(RTFQ-PCR)or immunoblot analysis to assess METTL14 expression in EC.The expression of METTL14 and its correlation with clinicopathological features of EC were assessed.The biological effects of METTL14 in EC were determined in vitro and in vivo.Methylated RNA immunoprecipitation sequencing(MeRIP-seq)combined with RNA sequencing(RNA-seq),and following m6A dot blot,MeRIP-RTFQ-PCR,RIP-RTFQ-PCR or dual luciferase reporter assays were employed to screen and validate the candidate targets of METTL14.Results:The mRNA expression and protein levels of METTL14 were significantly downregulated in EC compared with matched adjacent tissues.Compared with the METTL14 high expression group,the METTL14 low expression group had a significant increase in International Federation of Gynecology and Obstetrics(FIGO)stage,infiltration depth,lymphovascular invasion,lymph node metastasis and the number of cases of tumor metastasis(P<0.05).Functionally,METTL14 inhibited the proliferation and invasive capacity of EC cells in vitro and in vivo.Mechanistically,METTL14-mediated demethylation of m6A resulted in post-transcriptional repression of estrogen receptor alpha(ERα).Furthermore,compared with METTL14,ERαinduced oncogenic behavior of tumors.Conclusion:METTL14 attenuates ERαexpression in EC cells in a m6A-dependent manner,thereby inhibiting tumor metastasis and invasion.