STUDIES ON 17β-HYDROXYSTEROID DEHYDROGENASE IN HUMAN ENDOMETRIUM AND ENDOMETRIAL CARCINOMA

Abstract

ABSTRACT Specific activity of 17β-hydroxysteroid dehydrogenase (17β-HSD) was measured in subcellular fractions of normal endometrium at different phases of the menstrual cycle, and of endometrial carcinoma at different degrees of differentiation. The purity of fractions was determined by marker enzymes, RNA/DNA ratio or electronmicrographs. Both in normal and neoplastic tissue 17β-HSD activity was located mainly in mitochondria and microsomes. The microsomal enzyme is bound tightly to the membranes of the endoplasmic reticulum. While in normal endometrium specific enzyme activity in subcellular fractions depended on the phase of the cycle, in endometrial carcinoma it depended on the degree of differentiation of the tumours. The highest values of 17β-HSD activity were found in mitochondria and microsomes of early secretory endometrium (factor 10 as compared to proliferative endometrium) and in particulate fractions of well differentiated carcinoma (factor 10 to ⪢ 10 as compared to undifferentiated carcinoma).