STEROID SULFATASE ACTIVITY IN OSTEOBLAST CELLS

We have demonstrated steroid sulfatase activity in osteoblast cells an d characteristics of the enzyme were also investigated, Cell free homo genate of Pat osteoblast cell line, UMR106-01 and human osteoblast cel l lines, MG-63, HOS were incubated with [H-3] dehydroepiandrosterone-s ulfate (DHEA-sulfate) or [H-3] estrone-sulfate (E(1)-sulfate). The for mation of DHEA or E(1) from the corresponding substrate was identified by crystallization to constant specific activity, Michaelis constant (Km) for DHEA-sulfate. was estimated as 2.1 x 10(-8)M in UMR106-01, 7. 4 x 10(-7)M in MG-63, 5.8 x 10(-7)M in HOS and that for E(1)-sulfate w as: 4.1 x 10(-7)M, 3.0 x 10(-7)M, 9.8 x 10(-7)M, respectively. The exp ression of steroid sulfatase messenger ribonucleic acid in human osteo blast cells, NOS and MG-63 was first demonstrated by reverse transcrip tion-polymerase chain reaction. The existence of steroid sulfatase in human and rat osteoblast cells suggests that osteoblast cells have the capacity to convert circulating sulfo-conjugated steroids to more act ive androgens and estrogens, This may indicate an important role of bo ne in facilitating hormonal action. (C) 1997 Academic Press.