Bone degradation is a serious complication of chronic inflammatory diseases such as septic arthritis, osteomyelitis and infected orthopedic implant failure. At present, effective therapeutic treatments for lipopolysaccharide (LPS)-induced bone destruction are limited to antibiotics and surgical repair in chronic inflammatory diseases. The present study aimed to evaluate the mechanism of LPS on osteoclast differentiation and activation. RAW264.7 cells were non-induced, or induced by the receptor activator of nuclear factor-κB (RANK) ligand (RANKL) and macrophage-colony stimulating factor (M-CSF), and then treated with LPS. Following treatment, the number of osteoclasts and cell viability were measured. The expression of osteoclast-related genes including tartrate-resistant acid phosphatase (TRAP), matrix metalloproteinase-9 (MMP-9), cathepsin K (CK), carbonic anhydrase II (CAII) and cyclooxygenase-2 (COX-2) was determined by RT-PCR. Protein levels of RANK, tumor necrosis factor receptor-associated factor 6 (TRAF6), COX-2 and mitogen-activated protein kinases (MAPK) were measured using western blotting assays. LPS promoted osteoclast differentiation of RAW264.7 cells and differentiated osteoclasts. LPS significantly increased mRNA expression of osteoclast-related genes in RAW264.7 cells. Differentiated osteoclasts were treated with LPS (100 ng/ml) and the results showed a significantly increased mRNA expression of osteoclast-related genes and protein levels of RANK, TRAF6 and COX-2. Furthermore, LPS at 100 ng/ml significantly promoted the MAPK pathway including increasing the phosphorylation of c-Jun N-terminal kinases (JNK) and the phosphorylation of the extracellular signal-regulated kinase (ERK1/2). In conclusion, LPS promoted osteoclast differentiation and activation by enhancing RANK signaling and COX-2 expression. LPS also promoted osteoclast differentiation via activation of the JNK and ERK1/2 cell proliferation pathways.

Aims: Quercetin, a flavonoid present in vegetables, has anti-inflammatory properties and potential inhibitory effects on bone resorption. Up to date, the effect of quercetin on lipopolysaccharide (LPS)-induced osteoclastogenesis has not yet been reported. In the current study, we evaluated the effect of quercetin on LPS-induced osteoclast apoptosis and bone resorption. Methods: RAW264.7 cells were non-treated, treated with LPS alone, or treated with both LPS and quercetin. After treatment, the number of osteoclasts, cell viability, bone resorption and osteoclast apoptosis were measured. The expressions of osteoclast-related genes including tartrate-resistant acid phosphatase (TRAP), matrix metalloproteinase-9 (MMP9) and cathepsin K (CK) were determined by real-time quantitative polymerase chain reaction (qPCR). Protein levels of receptor activator of nuclear factor-ĸB (RANK), tumor necrosis factor receptor-associated factor 6 (TRAF6), cyclooxygenase-2 (COX-2), Bax, Bcl-2 and mitogenactivated protein kinases (MAPKs) were measured using Western blotting assays. The MAPK signaling pathway was blocked by pretreatment with MAPK inhibitors. Results: LPS directly promoted osteoclast differentiation of RAW264.7 cells and upregulated the protein expression of RANK, TRAF6 and COX-2; while quercetin significantly decreased the number of LPS-induced osteoclasts in a dose-dependent manner. None of the treatments increased cytotoxicity in RAW264.7 cells. Quercetin inhibited mRNA expressions of osteoclast-related genes and protein levels of RANK, TRAF6 and COX-2 in LPS-induced mature osteoclasts. Quercetin also induced apoptosis and inhibited bone resorptive activity in LPS-induced mature osteoclasts. Furthermore, quercetin promoted the apoptotic signaling pathway including increasing the phosphorylation of p38-MAPK, c-Jun N-terminal kinases/stress-activated protein kinases

Ovarian cancer remains the most lethal gynecologic malignancy with late detection and acquired chemoresistance. Advanced understanding of the pathophysiology and novel treatment strategies are urgently required. A growing body of proteomic investigations suggest that phosphorylation has a pivotal role in the regulation of ovarian cancer associated signaling pathways. Matrine has been extensively studied for its potent anti-tumor activities. However, its effect on ovarian cancer cells and underlying molecular mechanisms remain unclear. Herein we showed that matrine treatment inhibited the development and progression of ovarian cancer cells by regulating proliferation, apoptosis, autophagy, invasion and angiogenesis. Matrine treatment retarded the cancer associated signaling transduction by decreasing the phosphorylation levels of ERK1/2, MEK1/2, PI3K, Akt, mTOR, FAK, RhoA, VEGFR2, and Tie2 in vitro and in vivo. Moreover, matrine showed excellent antitumor effect on chemoresistant ovarian cancer cells. No obvious toxic side effects were observed in matrine-administrated mice. As the natural agent, matrine has the potential to be the targeting drug against ovarian cancer cells with the advantages of overcoming the chemotherapy resistance and decreasing the toxic side effects.

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BackgroundGlioblastomas multiforme (GBM) is the most devastating primary intracranial malignancy lacking effective clinical treatments. Notch2 has been established to be a prognostic marker and probably involved in GBM malignant progression. N-acetylcysteine (NAC), a precursor of intracellular glutathione (GSH), has been widely implicated in prevention and therapy of several cancers. However, the role of NAC in GBM remains unclear and the property of NAC independent of its antioxidation is largely unknown.MethodsThe mRNA and protein levels of Notch family and other related factors were detected by RT-PCR and western blot, respectively. In addition, intracellular reactive oxygen species (ROS) was measured by flow cytometry-based DCFH-DA. Moreover, cell viability was assessed by CCK8 and cell cycle was analyzed by flow cytometry-based PI staining. The level of apoptosis was checked by flow cytometry-based Annexin V/PI. Cell migration and invasion were evaluated by wound healing and transwell invasion assays. At last, U87 Xenograft model was established to confirm whether NAC could restrain the growth of tumor.ResultsOur data showed that NAC could decrease the protein level of Notch2. Meanwhile, NAC had a decreasing effect on the mRNA and protein levels of its downstream targets Hes1 and Hey1. These effects caused by NAC were independent of cellular GSH and ROS levels. The mechanism of NAC-mediated Notch2 reduction was elucidated by promoting Notch2 degradation through Itch-dependent lysosome pathway. Furthermore, NAC could prevent proliferation, migration, and invasion and might induce apoptosis in GBM cells via targeting Notch2. Significantly, NAC could suppress the growth of tumor in vivo.ConclusionsNAC could facilitate Notch2 degradation through lysosomal pathway in an antioxidant-independent manner, thus attenuating Notch2 malignant signaling in GBM cells. The remarkable ability of NAC to inhibit cancer cell proliferation and tumor growth may implicate a novel application of NAC on GBM therapy.Electronic supplementary materialThe online version of this article (10.1186/s13046-018-1016-8) contains supplementary material, which is available to authorized users.