Smith Joel, Read Martin L, Hoffman Jon, Brown Rachel, Bradshaw Beth, Campbell Christopher, Cole Trevor, Navas Johanna Dieguez, Eatock Fiona, Gundara Justin S, Lian Eric, Mcmullan Dom, Morgan Neil V, Mulligan Lois, Morrison Patrick J, Robledo Mercedes, Simpson Michael A, Smith Vicki E, Stewart Sue, Trembath Richard C, Sidhu Stan, Togneri Fiona S, Wake Naomi C, Wallis Yvonne, Watkinson John C, Maher Eamonn R, McCabe Christopher J, Woodward Emma R
Centre for Rare Diseases and Personalised Medicine.
School of Clinical and Experimental Medicine, University of Birmingham, Birmingham B15 2TT, UK.
Hum Mol Genet. 2016 May 1;25(9):1836-45. doi: 10.1093/hmg/ddw057. Epub 2016 Mar 3.
Familial medullary thyroid cancer (MTC) and its precursor, C cell hyperplasia (CCH), is associated with germline RET mutations causing multiple endocrine neoplasia type 2. However, some rare families with apparent MTC/CCH predisposition do not have a detectable RET mutation. To identify novel MTC/CCH predisposition genes we undertook exome resequencing studies in a family with apparent predisposition to MTC/CCH and no identifiable RET mutation. We identified a novel ESR2 frameshift mutation, c.948delT, which segregated with histological diagnosis following thyroid surgery in family members and demonstrated loss of ESR2-encoded ERβ expression in the MTC tumour. ERα and ERβ form heterodimers binding DNA at specific oestrogen-responsive elements (EREs) to regulate gene transcription. ERβ represses ERα-mediated activation of the ERE and the RET promoter contains three EREs. In vitro, we showed that ESR2 c.948delT results in unopposed ERα mediated increased cellular proliferation, activation of the ERE and increased RET expression. In vivo, immunostaining of CCH and MTC using an anti-RET antibody demonstrated increased RET expression. Together these findings identify germline ESR2 mutation as a novel cause of familial MTC/CCH and provide important insights into a novel mechanism causing increased RET expression in tumourigenesis.
家族性甲状腺髓样癌（MTC）及其前驱病变C细胞增生（CCH）与导致2型多发性内分泌肿瘤的种系RET突变相关。然而，一些明显具有MTC/CCH易感性的罕见家族并未检测到RET突变。为了鉴定新的MTC/CCH易感基因，我们对一个明显具有MTC/CCH易感性且未发现可识别的RET突变的家族进行了外显子组重测序研究。我们鉴定出一个新的ESR2移码突变，即c.948delT，该突变在家族成员甲状腺手术后与组织学诊断结果共分离，并在MTC肿瘤中显示ESR2编码的ERβ表达缺失。ERα和ERβ形成异二聚体，在特定的雌激素反应元件（ERE）处结合DNA以调节基因转录。ERβ抑制ERα介导的ERE激活，而RET启动子包含三个ERE。在体外，我们发现ESR2 c.948delT导致ERα介导的细胞增殖增加、ERE激活以及RET表达增加且不受抑制。在体内，使用抗RET抗体对CCH和MTC进行免疫染色显示RET表达增加。这些发现共同确定种系ESR2突变是家族性MTC/CCH的一个新病因，并为肿瘤发生过程中导致RET表达增加的新机制提供了重要见解。
