STERYLSULFATASE EXPRESSION IN NORMAL AND TRANSFORMED HUMAN PLACENTAL CELLS

Isolated cytotrophoblast cells and choriocarcinoma cell lines are commonly applied in-vitro systems for the study of human placental endocrine function. We tested these normal and transformed placental cells for expression of the enzyme sterylsulfatase which is necessary for the production of free steroids from sulfoconjugated precursors in the placenta as well as in other human tissues, and compared the results with respective data obtained from term placental tissue. Specific sterylsulfatase activity was highest in placental homogenates but was lower by about a factor of 5 to 10 in homogenates of freshly isolated cytotrophoblast or JEG-3 cells and by about a factor of 100 in BeWo cell homogenates; the enzyme activity could not be detected in Jar cells. Sterylsulfatase mRNA levels as analyzed by Northern blotting roughly paralleled the levels of enzyme activity measured in cytotrophoblast, JEG-3, and BeWo cells; in Jar cells, RNA species complementary to the specific probe were clearly detectable but differed by size from the mRNA species found in the other cells. Our results indicate that sterylsulfatase activity is differently expressed in normal and transformed placental cells due to different rates or products of gene transcription in these cells.