Fax +41 61 306 12 34 E-Mail karger@karger.ch www.karger.com Original Article Gynecol Obstet Invest 2009;67:118–126 DOI: 10.1159/000167798 Expression of the Epidermal Growth Factor System in Eutopic Endometrium from Women with Endometriosis Differs from That in Endometrium from Healthy Women Kirsten Ejskjær a, † Boe Sandahl Sorensen a Steen Seier Poulsen b Ole Mogensen c Axel Forman d Ebba Nexo a a Department of Clinical Biochemistry, Aarhus University Hospital, Aarhus, b Department of Medical Anatomy, Panum Institute, University of Copenhagen, Copenhagen, c Department of Gynecology and Obstetrics, Odense University Hospital, Odense, and d Department of Gynecology and Obstetrics, Aarhus University Hospital, Skejby, Aarhus, Denmark histochemically, HER2 was identified in all samples, predom- inately in glands and surface epithelium. In a few glands, HER2 was in both cytoplasm and cell membrane. Conclu- sion: We report quantitative and qualitative differences in the EGF system in endometriotic eutopic endometrium compared to endometrium from healthy individuals. Copyright © 2008 S. Karger AG, Basel Introduction The epidermal growth factor (EGF) system consists of four receptors, human epidermal growth factor receptor 1 (HER1) (also named EGFreceptor/EGFr/ErbB1), HER2 (also named ErbB2), HER3, and HER4. The receptors are trans-membrane glycoproteins with an extracellular li- gand-binding domain, a trans-membrane region, and an intracellular domain with tyrosine kinase activity. A number of ligands, the EGF-related peptide growth fac- tors, bind to the receptors. One group consists of EGF, amphiregulin (AR), transforming growth factor-  (TGF- Key Words Human endometrium  Endometriosis  Epidermal growth factor system Abstract Background: The epidermal growth factor (EGF) system comprises four receptors, HER1–4, and several ligands, and is cyclically expressed in endometrium from healthy fertile women. Our aim is to identify differences in expression of the EGF system between endometriotic and normal endo- metrium. Methods: We previously examined the EGF system in endometrial samples from healthy women (n = 14). Here we examine samples from endometrium (n = 23), endome- triomas (n = 10) and peritoneal endometriosis (n = 9) from women with endometriosis (n = 23). mRNA expression of re- ceptors and ligands from the EGF system was analyzed by real-time PCR, and proteins were localized by immunohisto- chemistry. Results: Endometrial mRNA for HER1–3 was high compared with our previous findings in healthy endometri- um, whereas HER4 and the ligands were unchanged. Endo- metriomas show lower expression of HER1–3 and no HER4 expression. Significant differences were demonstrated in late secretory phase for HER1 and HER2 and in the prolifera- tive phase for HER3 compared to healthy women. Immuno- Received: January 22, 2008 Accepted after revision: August 18, 2008 Published online: November 6, 2008 Boe Sandahl Sorensen Department of Clinical Biochemistry, Aarhus University Hospital Norrebrogade 44 DK–8000 Aarhus C (Denmark) Tel. +45 89 49 30 48, Fax +45 89 49 30 60, E-Mail boess@as.aaa.dk © 2008 S. Karger AG, Basel 0378–7346/09/0672–0118$26.00/0 Accessible online at: www.karger.com/goi † This article is dedicated to the memory of the first author, Kirsten Ejskjær, who died of leukemia after completing this paper.