The inhibitory effect of bisphosphonates on glucocorticoid-induced RANKL expression in human cells.
OBJECTIVE
RANKL is known to play an important role in activating osteoclasts and advancing the progress of osteoporosis. However, little is known about the effect of bisphosphonates on glucocorticoid-induced RANKL expression in human cells. Our study was intended to clarify effects of bisphosphonates on glucocorticoid-induced RANKL expression in human cells.


METHODS
Human T lymphoblastic cell line Jurkat and human osteosarcoma cell line MG-63 were used for the following experiments. RANKL expression in two cell lines was measured using reverse transcription polymerase chain reaction (RT-PCR) analysis and enzyme immunoassay (EIA). Luciferase assays using pGRE-Luc were also performed.


RESULTS
In Jurkat and MG-63 cells, dexamethasone induced expression of soluble RANKL (sRANKL) protein in supernatants and RANKL mRNA in cells. Moreover, bisphosphonates, but not cyclooxygenase inhibitors, repressed dexamethasone-induced sRANKL protein production. By contrast, glucocorticoid receptor-driven transcriptional activity was not inhibited by bisphosphonates.


CONCLUSIONS
Glucocorticoid induced RANKL expression in human cells derived from T lymphocytes and osteoblasts. Bisphosphonates inhibited glucocorticoid-induced RANKL expression, suggesting that these effects might be a new therapeutic mechanism for bisphosphonates.
Kobayashi
A
A
Second Department of Internal Medicine, Asahikawa Medical College, Asahikawa, Japan.
Hirano
F
F
Makino
I
I
D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D004164:Diphosphonates / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D019169:Jurkat Cells / Q000187:drug effects / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000235:genetics* / Q000378:metabolism; D010006:Osteoblasts / Q000187:drug effects / Q000378:metabolism; D012516:Osteosarcoma / Q000188:drug therapy / Q000378:metabolism; D053245:RANK Ligand; D012333:RNA, Messenger / Q000378:metabolism; D053246:Receptor Activator of Nuclear Factor-kappa B; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism
D000893:Anti-Inflammatory Agents; D050071:Bone Density Conservation Agents; D002352:Carrier Proteins; D004164:Diphosphonates; D005938:Glucocorticoids; D008562:Membrane Glycoproteins; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; C505686:TNFRSF11A protein, human; C505688:TNFSF11 protein, human; D003907:Dexamethasone