Tetramethylpyrazine Protects Against Glucocorticoid-Induced Apoptosis by Promoting Autophagy in Mesenchymal Stem Cells and Improves Bone Mass in Glucocorticoid-Induced Osteoporosis Rats.

Glucocorticoid-induced osteoporosis (GIOP) is a widespread clinical complication due to the common use of glucocorticoids. Excess glucocorticoids induce apoptosis of bone marrow-derived mesenchymal stem cells (BMSCs), which have been shown to play an increasingly important role in the pathogenesis and therapy of osteoporosis. Tetramethylpyrazine (TMP), an extract from one of the most recognized herbs in traditional Chinese medicine (Chuanxiong), has been reported to have antiapoptotic properties. In this study, we tested whether TMP protects rat BMSCs following exposure to glucocorticoids in vitro and in vivo. We treated BMSCs with different concentrations of TMP (50, 100, or 200 µM) and exposed them to 10-6 M dexamethasone (Dex) for 48 h in vitro. Our data showed that TMP inhibited Dex-induced cytotoxicity and protected BMSCs from apoptosis. Interestingly, further results demonstrated that TMP prevented apoptosis in BMSCs by promoting autophagy in an AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) pathway-dependent manner. In addition, calcein fluorescence double labeling and microcomputed tomography scanning indicated that 12 weeks of TMP administration augmented bone formation and protected trabecular bone mass in GIOP rats. We also discovered that first-passage BMSCs isolated from the TMP treatment group had a lower rate of apoptosis and a higher light chain 3 (LC3)-II/LC3-I ratio than the GIOP group. Our findings demonstrate for the first time that TMP can protect BMSCs from exposure to excess glucocorticoids by promoting autophagy through AMPK/mTOR pathway and might be an effective agent for the prevention and treatment of GIOP.

Expression of CD147, PCNA, VEGF, MMPs and their clinical significance in the giant cell tumor of bones.

BACKGROUND: Giant cell tumor of bone (GCT) is a potentially malignant tumor. CD147 is a multifunctional protein, which expresses itself in many tumors. In this study, we have investigated the correlation between CD147 and PCNA, VEGF, MMPs expression in giant cell tumor of bones. We have also explored the relationship between its clinical pathology and prognosis. RESULTS: A significant difference of the expression level of CD147, MMPs was found in cases of GCT with Jaffe grading and prognosis (P<0.05). But, it was not in accordance with the patient's age and sex. An expression of CD147 was positively correlated with MMP-9, VEGF, MVD, PCNA (r=0.271, P=0.025; r=0.411, P=0.000; r=0.872, P=0.000; r=0.394, P=0.001). CONCLUSION: The expression level of CD147 in giant cell tumors of bones is correlated with the development of cancers and relapse. There was a positive correlation between expressions of CD147 and MMP-9, VEGF, MVD, PCNA, and CD147. This is an important indicator in evaluating the malignant degree and prognosis of giant cell tumors of bone. It may be the new target for ensuring chemopreventive strategies.

Gastrodin: an ancient Chinese herbal medicine as a source for anti-osteoporosis agents via reducing reactive oxygen species.

Increased levels of reactive oxygen species (ROS) are a crucial pathogenic factor of osteoporosis. Gastrodin, isolated from the traditional Chinese herbal agent Gastrodia elata, is a potent antioxidant. We hypothesized that gastrodin demonstrates protective effects against osteoporosis by partially reducing reactive oxygen species in human bone marrow mesenchymal stem cells (hBMMSCs) and a macrophage cell line (RAW264.7 cells). We investigated gastrodin on osteogenic and adipogenic differentiation under oxidative stress in hBMMSCs. We also tested gastrodin on osteoclastic differentiation in RAW264.7 cells. Hydrogen peroxide (H2O2) was used to establish an oxidative cell injury model. Our results showed that gastrodin significantly promoted the proliferation of hBMMSCs, improved some osteogenic markers, reduced lipid generation and inhibited the mRNA expression of several adipogenic genes in hBMMSCs. Moreover, gastrodin reduced the number of osteoclasts, TRAP activity and the expression of osteoclast-specific genes in RAW264.7 cells. Gastrodin suppressed the production of reactive oxygen species in both hBMMSCs and RAW264.7 cells. In vivo, we established a murine ovariectomized (OVX) osteoporosis model. Our data revealed that gastrodin treatment reduced the activity of serum bone degradation markers, such as CTX-1 and TRAP. Importantly, it ameliorated the micro-architecture of trabecular bones. Gastrodin decreased osteoclast numbers in vivo by TRAP staining. To conclude, these results indicated that gastrodin shows protective effects against osteoporosis linking to a reduction in reactive oxygen species, suggesting that gastrodin may be useful in the prevention and treatment of osteoporosis.

Ginsenoside-Rb2 inhibits dexamethasone-induced apoptosis through promotion of GPR120 induction in bone marrow-derived mesenchymal stem cells.

Apoptosis of bone marrow-derived mesenchymal stem cells (BMMSCs) is an essential pathogenic factor of osteoporosis. Ginsenoside-Rb2 (Rb2), a 20(S)-protopanaxadiol glycoside extracted from ginseng, is a potent treatment for bone loss, which raises interest regarding the bone metabolism area. In the present study, we found that dose-response Rb2 inhibited high dosage of dexamethasone (Dex)-induced apoptosis in primary murine BMMSCs. Interestingly, Rb2 promoted GPR120 induction, which is the unsaturated long-chain fatty acid receptor. We further confirmed that GPR120-specific ShRNA reversed the inhibition of Rb2 on Dex-induced apoptosis by activating caspase-3 and reducing cell viability. In addition, Rb2 notably increased phosphorylated ERK1/2 levels and Ras kinase activity dependently through the GPR120. The ERK1/2 activity-specific inhibitor U0126 remarkably blocked the Rb2-induced antiapoptotic effect in response to Dex-induced apoptosis. Together, dose-response Rb2 protected BMMSCs against Dex-induced apoptosis dependently by inducing GPR120 promoted Ras-ERK1/2 signaling pathway. Therefore, in the prevalence of the abuse of Dex in the clinic, our findings suggest for the first time that Rb2 is not only a key to understand the link between Chinese medicine and the pathology of osteoporosis but also an underlying target for the treatment of bone complications in the foreseeable future.

Dose-dependent effect of estrogen suppresses the osteo-adipogenic transdifferentiation of osteoblasts via canonical Wnt signaling pathway.

Fat infiltration within marrow cavity is one of multitudinous features of estrogen deficiency, which leads to a decline in bone formation functionality. The origin of this fat is unclear, but one possibility is that it is derived from osteoblasts, which transdifferentiate into adipocytes that produce bone marrow fat. We examined the dose-dependent effect of 17ß-estradiol on the ability of MC3T3-E1 cells and murine bone marrow-derived mesenchymal stem cell (BMMSC)-derived osteoblasts to undergo osteo-adipogenic transdifferentiation. We found that 17ß-estradiol significantly increased alkaline phosphatase activity (P<0.05); calcium deposition; and Alp, Col1a1, Runx2, and Ocn expression levels dose-dependently. By contrast, 17ß-estradiol significantly decreased the number and size of lipid droplets, and Fabp4 and PPARγ expression levels during osteo-adipogenic transdifferentiation (P<0.05). Moreover, the expression levels of brown adipocyte markers (Myf5, Elovl3, and Cidea) and undifferentiated adipocyte markers (Dlk1, Gata2, and Wnt10b) were also affected by 17ß-estradiol during osteo-adipogenic transdifferentiation. Western blotting and immunostaining further showed that canonical Wnt signaling can be activated by estrogen to exert its inhibitory effect of osteo-adipogenesis. This is the first study to demonstrate the dose-dependent effect of 17ß-estradiol on the osteo-adipogenic transdifferentiation of MC3T3-E1 cells and BMMSCs likely via canonical Wnt signaling. In summary, our results indicate that osteo-adipogenic transdifferentiation modulated by canonical Wnt signaling pathway in bone metabolism may be a new explanation for the gradually increased bone marrow fat in estrogen-inefficient condition.

17ß-Estradiol inhibits ER stress-induced apoptosis through promotion of TFII-I-dependent Grp78 induction in osteoblasts.

Although many studies have suggested that estrogen prevents postmenopausal bone loss partially due to its anti-apoptosis effects in osteoblasts, the underlying mechanism has not been fully elucidated. In the present study, we found that 17ß-estradiol (17ß-E2), one of the primary estrogens, inhibited endoplasmic reticulum (ER) stress-induced apoptosis in MC3T3-E1 cells and primary osteoblasts. Interestingly, 17ß-E2-promoted Grp78 induction, but not CHOP induction in response to ER stress. We further confirmed that Grp78-specific siRNA reversed the inhibition of 17ß-E2 on ER stress-induced apoptosis by activating caspase-12 and caspase-3. Moreover, we found that 17ß-E2 markedly increased the phosphorylated TFII-I levels and nuclear localization of TFII-I in ER stress conditions. 17ß-E2 stimulated Grp78 promoter activity in a dose-dependent manner in the presence of TFII-I and enhanced the binding of TFII-I to the Grp78 promoter. In addition, 17ß-E2 notably increased phosphorylated ERK1/2 levels and Ras kinase activity in MC3T3-E1 cells. The ERK1/2 activity-specific inhibitor U0126 remarkably blocked 17ß-E2-induced TFII-I phosphorylation and Grp78 expression in response to ER stress. Together, 17ß-E2 protected MC3T3-E1 cells against ER stress-induced apoptosis by promoting Ras-ERK1/2-TFII-I signaling pathway-dependent Grp78 induction.

ßig-h3 promotes human osteosarcoma cells metastasis by interacting with integrin α2ß1 and activating PI3K signaling pathway.

Osteosarcoma, the most common primary bone tumor in children and young adolescents, is characterized by local invasion and distant metastasis. But the detailed mechanisms of osteosarcoma metastasis are not well known. In the present study, we found that ßig-h3 promotes metastatic potential of human osteosarcoma cells in vitro and in vivo. Furthermore, ßig-h3 co-localized with integrin α2ß1 in osteosarcoma cells. But ßig-h3 did not change integrin α2ß1 expression in Saos-2 cells. Interaction of ßig-h3 with integrin α2ß1 mediates metastasis of human osteosarcoma cells. The second FAS1 domain of ßig-h3 but not the first FAS1 domain, the third FAS1 domain or the fourth FAS1 domain mediates human osteosarcoma cells metastasis, which is the α2ß1 integrin-interacting domain. We further demonstrated that PI3K/AKT signaling pathway is involved in ßig-h3-induced human osteosarcoma cells metastasis process. Together, these results reveal ßig-h3 enhances the metastasis potentials of human osteosarcoma cells via integrin α2ß1-mediated PI3K/AKT signal pathways. The discovery of ßig-h3-mediated pathway helps us to understand the mechanism of human osteosarcoma metastasis and provides evidence for the possibility that ßig-h3 can be a potential therapeutic target for osteosarcoma treatment.