Journal of BUON 10: 241-246, 2005 © 2005 Zerbinis Medical Publications. Printed in Greece ORIGINAL ARTICLE Radioligand binding assay determination of epidermal growth factor receptor in ovarian tumours S. Tomov 1 , D. Tzingilev 2 , G. Gorchev 1 , A. Velkova 3 , T. Vesselinova 4 , S. Popovska 4 1 Clinic of Gynecologic Oncology, Oncologic Center, Medical University, Pleven; 2 Clinic of Nuclear Medicine, National Oncological Hospital, Sofa; 3 Department of Social Medicine & Public Health, Medical University, Pleven; 4 Department of Pathology, Medical University, Pleven, Bulgaria Summary Purpose: To introduce a quantitative method for de- termination of epidermal growth factor receptor (EGFR) expression in tissue samples taken from normal ovaries, benign and malignant ovarian tumours, convenient for routine tests. Materials and methods: About 1g of tissue was taken intraoperatively from 136 patients; 105 of them had histologically verifed ovarian tumours (64 malignant, 42 benign) and 30 had normal ovaries. The tissue was frozen, preserved and transported in liquid nitrogen (–196 o C). The level and frequency of EGFR expression were determined by radioligand method, utilizing 125 I-labeled epidermal growth factor (EGF) and recombinant human EGF. The results were obtained as fmol bound EGF per mg protein from the membrane fraction. All samples having expression ≥3 fmol/mg were considered as positive. Results: The frequency of EGFR expression was 52% (70/136 patients), with a mean level of expression 45 ±11 fmol/mg (range 0-1332). From the EGFR-positive patients with malignant ovarian tumours 21 (62%) had progressive disease (PD) while only 4 (13%) patients with negative EGFR had PD (p=0.001). The mean progression-free in- terval in the frst group was 4 months, and in the second group it was 11 months (p=0.0028). Conclusion: The proposed quanitative radioligand binding assay is easy to perform, rapid and well reproduc- ible, and we recommend it for routine clinical use. Key words: EGFR, ovarian tumours, radioligand binding assay Introduction Cell survival is the result of a balance between cellular proliferation and programmed cell death (apoptosis). Cell membrane receptors and their as- sociated signal transducing proteins control these processes. Of the numerous receptors and signalling proteins described, protein kinases modulate most signalling pathways. Along the cell surface about 60 receptors with intrinsic tyrosine kinase activity are described. First recognized in 1980, these receptors can be subdivided into several families: the fam- ily of EGFRs, fibroblast growth factor receptors, platelet-derived growth factor receptors, etc [1]. EGFR family consists of 4 members: EGFR (Human Epidermal growth factor Receptor) HER1, HER2, HER3 and HER4 [2]. Mature human EGFR (HER1) is a glycoprotein, consisting of 1186 aminoacids with molecular weight 170 kD, being a product of EGFR protooncogene [2]. In EGFR structure identifed are an extracellular region (4 domains, 621 aminoacids), a transmembrane domain (23 hydrophobic aminoacids) and a cytoplasmic region, containing juxtamembrane tyrosine kinase and carboxyterminal domain. The ex- Received 06-02-2005; Accepted 25-02-2005 Author and address for correspondence: Dr. Slavcho Tomov Clinic of Gynecologic Oncology Oncologic Center Medical University Georgi Kochev street 8A Pleven 5800 Bulgaria Tel: +359 64 886 255 Fax: +359 64 801 603 E-mail: slavcho_tomov@yahoo.de