lithium-chloride and Osteoporosis

To provide a low-toxicity and high-efficacy clinical treatment for osteoporosis via a novel combination of LiCl and LY294002.. The protein levels of p-AKT, AKT, p-GSK3β, GSK3β, β-catenin, p-β-catenin, and NFATC1 were measured in osteoblasts and osteoclasts by Western blot. ALP activity and TRACP activity were measured using the corresponding kit. The levels of BALP, PINP, CTX, and TRACP-5b were determined in accordance with the requirements of the ELISA kits. Microstructural analysis was performed on the left distal femur using microcomputed tomography.. Treatment with the combination of LiCl and LY294002 led to a markedly increased osteoblast activity but significantly decreased osteoclast differentiation and bone absorption capacity compared with the treatment with LiCl or LY294002 alone (P < 0.01). In serum, the low-dose combination of LiCl and LY294002 significantly enhanced BALP levels (P < 0.01) and significantly decreased PINP, TRACP-5b, and CTX levels (P < 0.01) compared with the application of either drug alone.. This study indicates that drug combinations directed at multiple targets could be used for osteoporosis treatment by promoting osteoblast proliferation and inhibiting differentiation with high efficiency.

Topics: Animals; Chromones; Dose-Response Relationship, Drug; Drug Therapy, Combination; Female; Imaging, Three-Dimensional; Lithium Chloride; Morpholines; Osteoporosis; Ovariectomy; Rats; Rats, Sprague-Dawley; Treatment Outcome

Dexamethasone (Dex)-induced osteoporosis has been described as the most severe side effect in long-term glucocorticoid therapy. The decreased bone mass and the increased marrow fat suggest that Dex possibly shifts the differentiation of bone marrow stromal cells (BMSCs) to favor adipocyte over osteoblast, but the underlying mechanisms are still unknown. In this paper, we established a Dex-induced osteoporotic mouse model, and found that BMSCs from Dex-treated mice are more likely to differentiate into adipocyte than those from control mice, even under the induction of bone morphogenetic protein-2 (BMP2). We also discovered both in vitro and in vivo that the expression level of adipocyte regulator CCAAT/enhancer-binding protein alpha (C/EBPalpha) is significantly upregulated in Dex-induced osteoporotic BMSCs during osteoblastogenesis by a mechanism that involves inhibited DNA hypermethylation of its promoter. Knockdown of C/EBPalpha in Dex-induced osteoporotic cells rescues their differentiation potential, suggesting that Dex shifts BMSC differentiation by inhibiting C/EBPalpha promoter methylation and upregulating its expression level. We further found that the Wnt/beta-catenin pathway is involved in Dex-induced osteoporosis and C/EBPalpha promoter methylation, and its activation by LiCl rescues the effect of Dex on C/EBPalpha promoter methylation and osteoblast/adipocyte balance. This study revealed the C/EBPalpha promoter methylation mechanism and evaluated the function of Wnt/beta-catenin pathway in Dex-induced osteoporosis, providing a useful therapeutic target for this type of osteoporosis.

Topics: Adipocytes; Adipogenesis; Adiposity; Animals; Bone Density; Bone Morphogenetic Protein 2; CCAAT-Enhancer-Binding Protein-alpha; Dexamethasone; DNA Methylation; Gene Knockdown Techniques; Humans; Lithium Chloride; Male; Mesenchymal Stem Cells; Mice; Mice, Inbred C57BL; Osteoblasts; Osteogenesis; Osteoporosis; Promoter Regions, Genetic; Wnt Signaling Pathway

To explore the mechanism of glucocorticoid-induced osteoporosis, we investigated the effect of glucocorticoid on canonical Wnt signaling that emerged as a novel key pathway for promoting bone formation. Wnt3a increased the T-cell factor (Tcf)/lymphoid enhancer factor (Lef)-dependent transcriptional activity in primary cultured human osteoblasts. Dexamethasone suppressed this transcriptional activity in a dose-dependent manner, while 1,25-dihydroxyvitamin D3 increased this transcriptional activity. LiCl, an inhibitor of glycogen synthase kinase-3beta, also enhanced the Tcf/Lef-dependent transcriptional activity, which was, however, not inhibited by dexamethasone. The addition of anti-dickkopf-1 antibody partially restored the transcriptional activity suppressed by dexamethasone. Dexamethasone decreased the cytosolic amount of beta-catenin accumulated by Wnt3a and also inhibited the nuclear translocation of beta-catenin induced by Wnt3a. These data suggest that glucocorticoid suppresses the canonical Wnt signal in cultured human osteoblasts, partially through the enhancement of the dickkopf-1 production.

Topics: Active Transport, Cell Nucleus; Adjuvants, Immunologic; Calcitriol; Cell Line; Cell Nucleus; Cytosol; Dexamethasone; Dose-Response Relationship, Drug; Genes, Reporter; Genetic Vectors; Glucocorticoids; Green Fluorescent Proteins; Humans; Intercellular Signaling Peptides and Proteins; Lithium Chloride; Microscopy, Confocal; Osteoblasts; Osteoporosis; Plasmids; Proteins; Subcellular Fractions; Transcription, Genetic; Transcriptional Activation; Transfection; Wnt Proteins; Wnt3 Protein; Wnt3A Protein