Inhibition of cell invasion and protease activity by cholesterol sulfate.

We demonstrated that cholesterol sulfate (CS) inhibits invasion of a trophoblast cell line and plasmin enzyme activity in a noncompetitive manner by binding to the enzyme itself, suggesting that CS can repress cell invasion by inhibiting proteinases such as those involved in the plasminogen activator/plasmin system. Considering these results, it is possible that CS may act as a signaling molecule between the trophoblast and endometrium, and may regulate the process of implantation.