[The effects of 17 beta-estradiol on the expression of osteoprotegerin, the ligand of osteoprotegerin and related cytokines in osteosarcoma MG63 cells].

OBJECTIVE

To observe the regulative effects of 17 beta-estradiol (17 beta-E(2)) and ICI 182780 on the expression of osteoprotegerin (OPG), the ligand of osteoprotegerin (OPGL) and the related cytokines [macrophage colony-stimulating factor (M-CSF), TRAIL and transforming growth factor beta(TGF beta)] in MG63 cells.

METHODS

The expression of OPG, OPGL, M-CSF, TRAIL and TGF beta mRNA was examined by reverse transcriptase (RT)-PCR. The expression of OPG and OPGL protein was measured with Western blot.

RESULTS

(1) 17 beta-E(2) up-regulated the expression of OPG and TGF beta but down-regulated OPGL, M-CSF and TRAIL expression in MG63 cells. (2) ICI 182780 showed varied transactivating capability when regulating the expression of OPG, OPGL, TRAIL, M-CSF and TGF beta genes in MG63 cells.

CONCLUSIONS

(1) One of the key pathogenetic factors of postmenopausal osteoporosis is that estrogen deficiency leads to the decreasing expression of OPG and TGF beta but the increasing expression of some bone-resorbing cytokines such as OPGL, M-CSF and TRAIL in osteoblasts, then stimulation of osteoclast differentiation and activity which potentiates bone resorption and bone loss; (2) ICI 182780 shows partial transactivating activity in osteoblasts, so it should belong to a kind of selective estrogen receptor modulators.