Detection of micrometastasis by cytokeratin-20 (reverse transcription polymerase chain reaction) in lymph nodes of patients with endometrial cancer

Background. Cytokeratins are constituents of the intermediate filaments (IF s) of epithelial cells which are expressed in various combinations, dependi ng on the type of epithelium and degree of differentiation. We have reporte d (R. Zemer, A. Fishman, J. Bernheim, S. Zimlichman, O. Markowitz, M. Altar as, and A. Klein, Gynecol Oncol 70:410-413, 1998) on the determination of c ytokeratin-20 (CK-20) by reverse transcription polymerase chain reaction (R T-PCR) in the detection of endometrial cancer cells as a potential biomarke r. In that study, we also found that by using immunocytochemistry, most car cinomas were found to be negative for CK-20. The sensitivity and specificit y rates obtained by using the RT-PCR method were 94.4 and 91%, respectively . Objective. The aim of this study is to investigate the feasibility and pote ntial of the specific mRNA marker, CK-20, to detect endometrial cancer cell s-micrometastases (MMs)-by RT-PCR in lymph node (LN) samplings of patients undergoing hysterectomy for endometrial carcinoma. Method. We used the RT-PCR method to determine the expression of CK-20 in t he LNs of 20 patients [study group (SG)] who were being surgically staged a nd treated for endometrial carcinoma. The specificity of the mRNA CK-20 mar ker was examined in LNs obtained from five healthy patients [control group (CG)] who underwent abdominal hysterectomy and bilateral salpingooopherecto my for benign gynecologic conditions. The LNs obtained from the SG and CC p atients were prepared together before mRNA extraction. RNA of the various c ell pellets was extracted and RT-PCR was performed with CK-20 primers. RT-P CR products were analyzed by agarose gel electrophoresis and ethidium bromi de staining against PCR size markers. Specificity of the RT-PCR products wa s examined by Southern blotting. Results. Histopathologic examinations demonstrated the presence of metastas es in two (10%) SG patients. These patients were also CK-20 positive. Of th e remaining 18 patients with negative histopathologic results, 6 (33%) were CK-20 positive and 12 (67%) were negative. All the CG patients were CK-20 negative (specificity, 100%). Conclusions. The results obtained in this study suggest that RT-PCR of CK-2 0 is more sensitive than traditional histopathologic methods in the diagnos is of MMs in LNs of patients with endometrial cancer, Thus, due to the afor ementioned characteristics of CK-20, it may be considered a powerful biomar ker in the detection of MMs in LNs of patients with endometrial cancer. (C) 2000 Academic Press.