Aucubin Promotes Osteogenic Differentiation and Facilitates Bone Formation through the lncRNA-H19 Driven Wnt/ß-Catenin Signaling Regulatory Axis.

Objectives: Traditional Chinese medicine Cortex Eucommiae has been used to treat bone fracture for hundreds of years, which exerts a significant improvement in fracture healing. Aucubin, a derivative isolated from Cortex Eucommiae, has been demonstrated to possess anti-inflammatory, immunoregulatory, and antioxidative potential. In the present study, our aim was to explore its function in bone regeneration and elucidate the underlying mechanism. Materials and Methods: The effects of Aucubin on osteoblast and osteoclast were examined in mouse bone marrow-derived mesenchymal stem cells (BM-MSCs) and RAW 264.7 cells, respectively. Moreover, the lncRNA H19 and Wnt/ß-catenin signaling were detected by qPCR examination, western blotting, and luciferase activity assays. Using the femur fracture mice model, the in vivo effect of Aucubin on bone formation was monitored by X-ray, micro-CT, histomorphometry, and immunohistochemistry staining. Results: In the present study, Aucubin was found to significantly promote osteogenic differentiation in vitro and stimulated bone formation in vivo. Regarding to the underlying mechanism, H19 was found to be obviously upregulated by Aucubin in MSCs and thus induced the activation of Wnt/ß-catenin signaling. Moreover, H19 knockdown partially reversed the Aucubin-induced osteogenic differentiation and successfully suppressed the activation of Wnt/ß-catenin signaling. We therefore suggested that Aucubin induced the activation of Wnt/ß-catenin signaling through promoting H19 expression. Conclusion: Our results demonstrated that Aucubin promoted osteogenesis in vitro and facilitated fracture healing in vivo through the H19-Wnt/ß-catenin regulatory axis.

Baicalin induces ferroptosis in osteosarcomas through a novel Nrf2/xCT/GPX4 regulatory axis.

BACKGROUND: Osteosarcomas (OS) is a kind of malignant bone tumor which occurs primarily in children and adolescents, and the clinical therapeutics remain disappointing. As a new programmed cell death, ferroptosis is characterized by iron dependent and intracellular oxidative accumulation, which provides a potential alternative intervene for the OS treatment. Baicalin, a major bioactive flavone derived from traditional Chinese medicine Scutellaria baicalensis, has been proved to have anti-tumor properties in OS. Whether ferroptosis participated in the baicalin mediated anti-OS activity is an interesting project. PURPOSE: To explore the pro-ferroptosis effect and mechanisms of baicalin in OS. METHODS/STUDY DESIGN: Pro-ferroptosis effect of baicalin on cell death, cell proliferation, iron accumulation, lipid peroxidation production was determined in MG63 and 143B cells. The levels of glutathione (GSH), oxidized (GSSG) glutathione and malondialdehyde (MDA) were determined by enzyme linked immunosorbent assay (ELISA). The expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2), Glutathione peroxidase 4 (GPX4) and xCT were detected by western blot in baicalin-mediated ferroptosis regulation. In vivo, a xenograft mice model was adopted to explore the anticancer effect of baicalin. RESULTS: In the present study, it was found that baicalin significantly suppress tumor cell growth in vitro and in vivo. By promoting the Fe accumulation, ROS formation, MDA production and suppressing the ratio of GSH/GSSG, baicalin was found to trigger ferroptosis in OS and ferroptosis inhibitor ferrostatin-1 (Fer-1) successfully reversed these suppressive effects, indicating that ferroptosis participated in the baicalin mediated anti-OS activity. Mechanistically, baicalin physically interacted with Nrf2, a critical regulator of ferroptosis, and influenced its stability via inducing ubiquitin degradation, which suppressed the Nrf2 downstream targets GPX4 and xCT expression, and led to stimulating ferroptosis. CONCLUSIONS: Our findings for the first time indicated that baicalin exerted anti-OS activity through a novel Nrf2/xCT/GPX4-dependent ferroptosis regulatory axis, which hopefully provides a promising candidate for OS treatment.

Tectochrysin ameliorates murine allergic airway inflammation by suppressing Th2 response and oxidative stress.

Tectochrysin, a flavonoid compound, can be isolated from propolis, Alpinia oxyphylla Miq, and Lychnophora markgravii. This study evaluated the efficacy of tectochrysin in the treatment of shrimp tropomyosin (ST)-induced mouse asthma. Mice were sensitized with intraperitoneal (i.p.) injection of ST together with aluminum hydroxide as an adjuvant to establish a mouse model of asthma. Mice were i.p.-treated daily with tectochrysin. IgE levels in plasma, Th2 cytokines from both bronchoalveolar lavage (BAL) fluid and splenocytes, and CD200R on basophils in peripheral blood were measured. Histological analyses of lung tissues and accumulation of leukocytes in BAL fluid were performed. Lung eosinophil peroxidase, catalase and glutathione peroxidase activities were examined. ST was found to markedly increase eosinophilic inflammation and Th2 response in mice. Tectochrysin treatment reduced the level of IgE in plasma, the percentage of eosinophils in total white blood cells in peripheral blood, the total number of cells in BAL fluid, and eosinophil peroxidase activity in lung tissues. Tectochrysin attenuated ST-induced infiltration of eosinophils and epithelial mucus secretion in lung tissues and suppressed the overproduction of Th2 cytokines (IL-4 and IL-5) in BAL fluid. Tectochrysin also attenuated Th2 cytokine (IL-4 and IL-5) production from antigen-stimulated murine splenocytes in vitro, decreased the expression of CD200R on basophils in peripheral blood of asthmatic mice and inhibited IL-4 secretion from IgE-sensitized RBL-2H3 cells. In addition, tectochrysin enhanced catalase and glutathione peroxidase activities in lung tissues. Our findings demonstrate that TEC ameliorates allergic airway inflammation by suppressing Th2 response and oxidative stress.