In Situ Hybridization of EGFR mRNA in Normal, Dysplasic, Carcinoma In Situ and Malignant Cervical Tissues

Kim, T E; Kim, H K; Park, J S; Kim, J W; Kang, J H; Lee, A H; Kim, J H; Namkoong, S E

Abstract

The specific receptor for epidermal growth factor(EGFR) was first purified from the A431 cell line which was derived from an epiderrnal carcinoma of the vulva. It is a 170,000 dalton transmembrane glycoprotein and has three components, an extracellu~lar domain capable of binding the ligand, a transmembrane portion, and an intracellular domain facing the cytoplasm. The receptor is capable of binding epidermal growth factor (EGF), transforming growth factor(TGF) a, amphiregulin, and heparin-binding EGF. The function of EGFR is to bind the mitogen EGF or TGF alpha and to transduce the signal across the cell membrane to the cytoplasm. The intracellular component exhibits tyrosine kinase activity and has binding sites for ATP. This results in the autophosphorylation of the EGFR and phosphorylation of several target proteins. It has been suggested that the EGFR is overexpressed in the A431 cell line and that there is a close correlation hetween EGFR, EGFR mRNA overexpression and EGFR gene amplification. However this has not been always demonstrated in cervical cancers and cell lines. In this study, we compared the GEFR mRNA expression rates among normal(10 cases), dysplastic(10 cases), carcinoma in situ(CIS, 14 cases), and malignant cervical tissues(37 cases) and examed whether EGFR gene amplification is constant step in the malignant transformation of the cervical cells. Also, we studied the relationship between the results of EGFR expression and clinicopathologic findings to confirm the usefullness of the EGFR mRNS as a prognostic factor. The results were as follows. 1. The expression rate of EGFR mRNS were 60% in normal, 70% in dysplastic, 57% in CIS, and 59% malignant cervical tissue. 2. No significant difference was seen between the clinical stages and the expression rates in malignant cervical tissue tissue group. 3. According to the cell type, the expression rates of squamous cell carcinoma was significantly higher than that adenocarcinoma(P<0.05). 4. The clinicopathologic findings were not correlated with the expression rate of the malignant cervical tissue group. These results suggest that there is no EGFR gene amplification or EGFR overexpression on some malignant cervical tissues and that EGFR mRNA expression has less prognostic significance.