Steroid receptors in human osteoblast-like cells.

The presence and functions of steroid receptors were evaluated in three human osteosarcoma cell lines (OS1 = SA OS; OS2 = HOS TE 85, and OS3 = MNNG HOS TE 85). The human breast cancer cell line MCF-7 was used as internal control for oestrogen receptors (E2R). High and low affinity sites were characterised. The high affinity sites had a similar dissociation constant in all four cell lines. In contrast, the number of sites per cell was higher in MCF-7 cells. E2 did not significantly modify the number of progesterone receptors (PgR) per cell in any of the osteosarcoma lines. As expected, E2 increased the number of PgR sites per MCF-7 cell. 4-hydroxytamoxifen decreased the growth of MCF-7 cells only. OS1 and OS2 were sensitive only to the highest concentration tested, which produces only non-specific cytotoxic effects. Thus E2R and PgR were found in osteoblast-like cells, but the function of E2R in such cells remains unknown.