A PERMANENT HUMAN CELL-LINE (EA.HY926) PRESERVES THE CHARACTERISTICS OF ENDOTHELIN-CONVERTING ENZYME FROM PRIMARY HUMAN UMBILICAL VEIN ENDOTHELIAL-CELLS

Purification of endothelin converting enzyme (ECE) from endothelial ce lls has been hindered by the difficulty in obtaining primary endotheli al cells in large quantity. We therefore tested transformed human umbi lical vein endothelial cells (EA.hy 926) for ECE activity. Our data cl early demonstrate that this transformed cell line preserves the ECE pr operties of the primary eel line. These include: (i) one sharp activit y optimum at neutral pH; (ii) characteristics typical of a metalloprot ease; (iii) IC50 value for phosphoramidon of 1.8 mu M (2.7 mu M for HU VEC); (iv) no inhibition by captopril and thiorphan, inhibitors of ang iotensin converting enzyme and neutral endopeptidase 24.11. The enzyme showed a substrate specificity for big ET-1:big ET-2:big ET-3 in a ra tio of 40:2.5:1. This report presents evidence that a permanent human endothelial cell line, EA.hy926, preserves the ECE activity of HUVEC a nd is useful for the study of ECE and its regulation of ET-1 productio n.