Stimulation of human osteoblast differentiation and function by ipriflavone and its metabolites

Abstract

Ipriflavone (IP), an isoflavone derivative, has been shown to interfere with bone remodeling by inhibiting bone resorption and perhaps stimulating bone formation. In this study, we have analyzed the effect of IP and its metabolites on the differentiation and function of human osteoblastic cells. Bone marrow stromal osteoprogenitor cells (BMC) and trabecular bone osteoblasts (HOB) were isolated from human donors. The former can be induced to differentiate by treatment with dexamethasone, whereas the latter represent a more differentiated osteoblast. Incubation of BMC with metabolite III (10(-5) M) for 1 week induced modest but significant changes of alkaline phosphatase activity. Though both IP and metabolite III stimulated the expression of bone sialoprotein mRNA, a protein involved in cell attachment to the matrix, only metabolite III increased the steady-state level of decorin mRNA, a collagen fibrillogenesis-regulating proteoglycan. Metabolites III and V, but not the other isoflavones, increased the expression of type I collagen mRNA in HOB, whereas no detectable changes were observed in BMC cells with any of the experimental compounds. In HOB, an increased abundance of osteopontin and bone sialoprotein mRNA were also obtained after 1-week treatment with IP or metabolite V. No appreciable effects of IP or its metabolites were seen on osteocalcin expression and synthesis by either cell type. Finally, IP consistently increased the amount of 45Ca incorporated into the cell layer by BMC, and stimulated mineralization of both BMC and HOB, assessed by von Kossa staining. Thus, IP and its metabolites regulate the differentiation and biosynthetic properties of human bone-forming cells by enhancing the expression of some important matrix proteins and facilitating the mineralization process.

Ipriflavone inhibits osteolytic bone metastasis of human breast cancer cells in a nude mouse model

“…In addition, ipriflavone stimulates the proliferation of osteoblasts in vitro. [15][16][17] We are interested in examining the effect of ipriflavone on the formation of osteoblasts in osteolytic metastases.…”

“…For in vivo experiments, ipriflavone was suspended in water containing 0.5% (w/v) methylcellulose (Wako, Osaka, Japan) and given to mice orally at 6 or 12 mg/0.2 ml daily, which is equivalent to 200 or 400 mg/kg body weight. 18 -20 For in vitro experiments, ipriflavone was dissolved in absolute ethanol and added to the medium at 1-50 M. [11][12][13][14][15][16][17] The final ethanol concentrations were Ͻ0.5% (v/v). Control cells were treated with the same concentrations of ethanol.…”

“…[5][6][7][8] Some new bisphosphonates have been shown to be highly effective at suppressing tumor growth in vitro, 9,10 but whether they have direct antiproliferative or apoptosis-promoting actions on tumor cells in vivo remains unknown. 7,10 Ipriflavone, a synthetic phytoestrogen, has been shown to inhibit bone resorption [11][12][13][14] and stimulate osteoblast activity both in vitro [15][16][17] and in experimental animals. 18 -20 It is clinically used for the treatment of osteoporosis in some countries at the dose of 200 mg 3 times a day.…”

Four and Half Lim Protein 2 (FHL2) Stimulates Osteoblast Differentiation

“…Mineral deposition in the matrix was detected by Alizarin red S staining or by the uptake of 45 Ca as previously described. (29,31) …”

Inhibitory effects of genistein and resveratrol on guinea pig gallbladder contractility in vitro

“…Phytoestrogens represent a wide group of compounds which are naturally found in many plants, and they are defined as plant substances that are structurally or functionally similar to estradiol [5,6] . These natural products possess a wide spectr um of physiological and pharmacological effects such as estrogenic effects [7,8] , anti-atherosclerosis [9] , antiosteoporosis [10] , relieving menopausal symptoms [11] and the inhibitory effect of tyrosine kinases [12,13] . Recently, many papers indicate that phytoestrogen genistein and resveratrol can inhibit vasocontractile responses and relax vascular smooth muscles by a Ca 2+ antagonistic property which is very similar to estradiol [14,15] , and data from electrophysiological studies suggest genistein reversibly inhibits L-type calcium current in isolated guinea-pig ventricular myocytes in a concentrationdependent manner [16] .…”