STERYLSULFATASE EXPRESSION IN NORMAL AND TRANSFORMED HUMAN PLACENTAL CELLS

Isolated cytotrophoblast cells and choriocarcinoma cell lines are comm only applied in-vitro systems for the study of human placental endocri ne function. We tested these normal and transformed placental cells fo r expression of the enzyme sterylsulfatase which is necessary for the production of free steroids from sulfoconjugated precursors in the pla centa as well as in other human tissues, and compared the results with respective data obtained from term placental tissue. Specific steryls ulfatase activity was highest in placental homogenates but was lower b y about a factor of 5 to 10 in homogenates of freshly isolated cytotro phoblast or JEG-3 cells and by about a factor of 100 in BeWo cell homo genates; the enzyme activity could not be detected in Jar cells. Stery lsulfatase mRNA levels as analyzed by Northern blotting roughly parall eled the levels of enzyme activity measured in cytotrophoblast, JEG-3, and BeWo cells; in Jar cells, RNA species complementary to the specif ic probe were clearly detectable but differed by size from the mRNA sp ecies found in the other cells. Our results indicate that sterylsulfat ase activity is differently expressed in normal and transformed placen tal cells due to different rates or products of gene transcription in these cells.