OSTEOPROTEGERIN MESSENGER-RNA IS INCREASED BY INTERLEUKIN-1-ALPHA IN THE HUMAN OSTEOSARCOMA CELL-LINE MG-63 AND IN HUMAN OSTEOBLAST-LIKE CELLS

Osteoprotegerin (OPG) is a soluble receptor for the Osteoprotegerin-Li gand (OPGL) which is expressed on osteoblasts and mediates the signal for osteoclast differentiation. In the present study we demonstrate th at OPG mRNA levels in MG-63 cells are increased in a dose-dependent ma nner after 8 h of treatment with IL-1 alpha (338 +/- 53% over control at 25 U/ml). Interleukin-6 (IL-6), under similar culture conditions, d oes not affect OPC; mRNA levels. Time-course studies show that IL-1 al pha (25 U/ml) causes a transient increase of OPG mRNA levels in MG-63 cells, peaking after 4 h of treatment. An increase of the OPG transcri pt occurs in hOB cells at 0,5 h which is still present after 24 h of I L-1 alpha treatment. In MG-63 cells neither basal- nor IL-1 alpha-indu ced OPG mRNA levels are altered by the translational inhibitor cyclohe ximide. These results suggest that expression of OPG in osteoblasts ma y be regulated by IL-1 alpha. (C) 1998 Academic Press.