Differential activity of kaempferol and quercetin in attenuating tumor necrosis factor receptor family signaling in bone cells.

Abstract

Increasing data from epidemiological and in vitro studies show that the isoflavonoids, genistein and daidzein, and the flavonols, quercetin and kaempferol, are protective against postmenopausal bone loss. However, the physiological mechanisms for these effects are not well understood. We now report that kaempferol exerts profound antiosteoclastogenic effects by acting on both osteoblasts and osteoclasts. Kaempferol but not quercetin dose-dependently inhibited tumor necrosis factor alpha (TNFalpha)-induced production of the osteoclastogenic cytokines interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1/CCL2) in osteoblasts. The effect on IL-6 was posttranscriptional, whereas kaempferol reduced MCP-1 mRNA levels. In addition, in mouse primary calvarial osteoblasts, kaempferol but not quercetin blocked TNFalpha-induced translocation of the nuclear factor kappaB (NF-kappaB) subunit p65 from the cytoplasm to the nucleus. However, TNFalpha-stimulated intracellular ROS production was unaltered by kaempferol. In RAW264.7 cells, a monocyte/macrophage precursor for osteoclasts, both kaempferol and quercetin dose-dependently inhibited the receptor activator of NF-kappaB ligand (RANKL)-induced immediate-early oncogene c-fos expression at 6 h. After 3-5 days, both flavonols robustly inhibited RANKL-induced expression of the osteoclastic differentiation markers, RANK and calcitonin receptor. Consistent with down regulation of these osteoclastic differentiation markers, both flavonols strongly attenuated the RANKL-induced formation of multinucleated osteoclasts. However, kaempferol was more potent than quercetin in inhibiting RANKL-stimulated effects on RAW264.7 cells. Thus, our data indicate that kaempferol exerts profound antiosteoclastogenic effects by specifically antagonizing TNF receptor family action on bone cells at two distinct levels, by disrupting production of osteoclastogenic cytokines from osteoblasts and attenuating osteoclast precursor cell differentiation.

• Authors: Jian L Pang, Dennis A Ricupero, Su Huang, Nigar Fatma, Dhirendra P Singh, Jose R Romero, Naibedya Chattopadhyay
• Journal: Biochemical pharmacology (Biochem Pharmacol) Vol. 71 Issue 6 Pg. 818-26 (Mar 14 2006) ISSN: 0006-2952 [Print] England
• PMID: 16434028 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Drug Combinations
• Interleukin-6
• Kaempferols
• RNA, Messenger
• Tumor Necrosis Factor-alpha
• kaempferol
• Quercetin

Topics

• Animals
• Animals, Newborn
• Cell Line
• Dose-Response Relationship, Drug
• Drug Combinations
• Gene Expression Regulation (drug effects)
• Humans
• Interleukin-6 (metabolism)
• Kaempferols (pharmacology)
• Macrophages (drug effects, metabolism, pathology)
• Mice
• Mice, Inbred BALB C
• Osteoblasts (drug effects, metabolism, pathology)
• Quercetin (pharmacology)
• RNA, Messenger (analysis)
• Reverse Transcriptase Polymerase Chain Reaction
• Signal Transduction (drug effects)
• Tumor Necrosis Factor-alpha (metabolism, pharmacology)