Abstract
Steroid hormones influence the central nervous system by regulating important neuronal functions. Steroid sulfatase is an enzyme that hydrolyzes estrone-sulfate and neurosteroids, such as dehydroepiandrosterone-sulfate and pregnenolone-sulfate, to free steroids. This study is the first to demonstrate steroid sulfatase activity in human glioma cells. Steroid sulfatase activity was detected by the formation of estrone from [3 H ] estrone-sulfate and dehydroepiandrosterone from [3H] dehydroepiandrosterone-sulfate in whole cell assays using the human glioma cell line U-87 MG. The apparent Michaelis constants for estrone-sulfate and dehydroepiandrosterone-sulfate were estimated at 1.48μM and 0.80μM, respectively. Steroid sulfatase mRNA was detected in in U-87 MG cells by RT-PCR. Immunocytochemical staining using a polyclonal antibody against human placental steroid sulfatase localized the enzyme to the cell cytoplasm and processes. The presence of steroid sulfatase in human glioma cells suggests that they have the capacity to convert sulfo-conjugated steroids to free steroids, and therefore may play an important role in modulating hormonal action in the human brain.
