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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 βig-h3 promotes metastatic potential of human osteosarcoma cells in vitro and in vivo. Furthermore, βig-h3 co-localized with integrin α2β1 in osteosarcoma cells. But βig-h3 did not change integrin α2β1 expression in Saos-2 cells. Interaction of βig-h3 with integrin α2β1 mediates metastasis of human osteosarcoma cells. The second FAS1 domain of βig-h3 but not the first FAS1 domain, the third FAS1 domain or the fourth FAS1 domain mediates human osteosarcoma cells metastasis, which is the α2β1 integrin-interacting domain. We further demonstrated that PI3K/AKT signaling pathway is involved in βig-h3-induced human osteosarcoma cells metastasis process. Together, these results reveal βig-h3 enhances the metastasis potentials of human osteosarcoma cells via integrin α2β1-mediated PI3K/AKT signal pathways. The discovery of βig-h3-mediated pathway helps us to understand the mechanism of human osteosarcoma metastasis and provides evidence for the possibility that βig-h3 can be a potential therapeutic target for osteosarcoma treatment. [ABSTRACT FROM AUTHOR]

βig-h3 is a TGF-β (transforming growth factor β)-induced ECM (extracellular matrix) protein that induces the secretion of MMPs (matrix metalloproteinases). However, the mechanism of induction is yet to be established. In this study, siRNAs (small interfering RNAs) targeted against βig-h3 were transfected into SMMC-7721 cells [a HCC (human hepatocellular carcinoma) cell line] to knockdown the expression of βig-h3. We found that NiCl2, a potent blocker of extracellular Ca2+ entry, reduced βig-h3-induced secretion of MMP-2 and −9. Further investigation suggested that reduction in the levels of βig-h3 decreased the secretion of MMP-2 and −9 that was enhanced by an increase in the concentration of extracellular Ca2+. SNAP ( S-nitroso- N-acetylpenicillamine), a NO (nitric oxide) donor, and 8-Br-cGMP (8-bromo-cGMP) inhibited thapsigargin-induced Ca2+ entry and MMP secretion in the invasive potential of human SMMC-7721 cells. Further, the inhibitory effects of 8-Br-cGMP and SNAP could be significantly enhanced by down-regulating βig-h3. βig-h3 attenuates the negative regulation of NO/cGMP-sensitive store-operated Ca2+ entry. Our findings suggest that the expression of βig-h3 might play an important role in the regulation of store-operated Ca2+ entry to increase the invasive potential of HCC cells. [ABSTRACT FROM AUTHOR]

Compelling evidences suggest that transplantation of bone marrow‐derived mesenchymal stem cells (BM‐MSCs) can be therapeutically effective for central nervous system (CNS) injuries and neurodegenerative diseases. The therapeutic effect of BM‐MSCs mainly attributes to their differentiation into neuron‐like cells which replace injured and degenerative neurons. Importantly, the neurotrophic factors released from BM‐MSCs can also rescue injured and degenerative neurons, which plays a biologically pivotal role in enhancing neuroregeneration and neurological functional recovery. Tetramethylpyrazine (TMP), the main bioactive ingredient extracted from the traditional Chinese medicinal herb Chuanxiong, has been reported to promote the neuronal differentiation of BM‐MSCs. This study aimed to investigate whether TMP regulates the release of neurotrophic factors from BM‐MSCs. We examined the effect of TMP on brain‐derived neurotrophic factor (BDNF) released from BM‐MSCs and elucidated the underlying molecular mechanism. Our results demonstrated that TMP at concentrations of lower than 200 μM increased the release of BDNF in a dose‐dependent manner. Furthermore, the effect of TMP on increasing the release of BDNF from BM‐MSCs was blocked by inhibiting the phosphatidylinositol‐4,5‐bisphosphate 3‐kinase (PI3K)/protein kinase B (AKT)/cAMP‐response element binding protein (CREB) pathway. Therefore, we concluded that TMP could induce the release of BDNF from BM‐MSCs through activation of the PI3K/AKT/CREB pathway, leading to the formation of neuroprotective and proneurogenic microenvironment. These findings suggest that TMP possesses novel therapeutic potential to promote neuroprotection and neurogenesis through improving the neurotrophic ability of BM‐MSCs, which provides a promising nutritional prevention and treatment strategy for CNS injuries and neurodegenerative diseases via the transplantation of TMP‐treated BM‐MSCs. [ABSTRACT FROM AUTHOR]

Calpains are a conserved family of calcium-dependent cysteine proteinases involved in various cellular functions. Two ubiquitous isoforms, µ- and m-calpain, are key members of the calpain family that play essential roles in regulating cell migration and invasion. However, it remains unclear whether they are involved in the progression of hepatocellular carcinoma (HCC). Here, we investigated the functions of µ- and m-calpain in the invasive and metastatic processes of human hepatoma cells. Our results indicated that the expression levels of calpains were elevated in HCC cells compared with those in normal hepatic cells. Our results indicated that small interfering RNA (siRNA)-mediated silencing of µ- and m-calpain expressions significantly suppressed the adhesive, migrative and invasive potentials of human hepatoma cells. The matrix metalloproteinases (MMPs) are key regulators of malignant tumour invasion and metastasis. siRNA-mediated down-regulation of µ- and m-calpain expressions also significantly attenuated MMP-2 and MMP-9 secretion. Thus µ- and m-calpain may play important roles in the invasion and metastasis of human hepatoma cells, and calpains may be drug targets for preventing HCC metastasis. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 17β-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 17β-estradiol significantly increased alkaline phosphatase activity (P<0.05); calcium deposition; and Alp, Col1a1, Runx2, and Ocn expression levels dose-dependently. By contrast, 17β-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 17β-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 17β-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. [ABSTRACT FROM AUTHOR]