4-O-methylhonokiol inhibits colon tumor growth via p21-mediated suppression of NF-κB activity

Biphenolic components in the Magnolia family have shown several pharmacological activities such as antitumor effects. This study investigated the effects of 4-O-methylhonokiol (MH), a constituent of Magnolia officinalis, on human colon cancer cell growth and its action mechanism. 4-O-methylhonokiol (0–30 μM) decreased constitutive activated nuclear factor (NF)-κB DNA binding activity and inhibited growth of human colon (SW620 and HCT116) cancer cells. It also caused G₀–G₁ phase cell cycle arrest followed by an induction of apoptotic cell death. However, knockdown with small interfering RNA (siRNA) of p21 or transfection with cyclin D1/Cdk4 binding site-mutated p21 abrogated MH-induced cell growth inhibition, inhibition of NF-κB activity as well as expression of cyclin D1 and Cdk4. Conversely, inhibition of NF-κB with specific inhibitor or siRNA augmented MH-induced apoptotic cell death. 4-O-methylhonokiol inhibited tumor growth, NF-κB activity and expression of antiapoptotic proteins; however, it increased the expression of apoptotic proteins as well as p21 in xenograft nude mice bearing SW620 cancer cells. The present study reveals that MH causes p21-mediated human colon cancer cell growth inhibition through suppression of NF-κB and indicates that this compound by itself or in combination with other anticancer agents could be useful for the treatment of cancer.     

Osthole inhibits osteoclasts formation and bone resorption by regulating NF-κB signaling and NFATc1 activations stimulated by RANKL

Chinese herbal medicine Fructus Cnidii has an outstanding effect on chronic lumbar pain and impotence, also has been used against osteoporosis with high frequency. Yet, the mechanisms of osthole, a derivative of Fructus Cnidii, on osteoclasts remains barely known. In this study, it was found out that osthole (10⁻⁶mol/L, 10⁻⁵mol/L) had the influence of inhibiting osteoclast formation and bone resorptive activities induced by receptor activator of nuclear factor κB ligand (RANKL), rather than affecting the viability of osteoclast-like cells. Furthermore, osthole could also inhibit the messenger RNA expressions of c-Src, tartrate-resistant acid phosphatase, β3-Integrin, matrix metallopeptidase 9, and cathepsin K. The results of the mechanistic study indicated that osthole regulated the nuclear factor of activated T-cells cytoplasmic 1 (NFATc1) and nuclear factor-κB (NF-κB) activations following the RANKL stimulation. These findings suggested that the inhibitory effects of osthole were associated with restraining the activations of NFATc1 and NF-κB induced by RANKL. Thus osthole can be used as a potential treatment for abnormal bone-resorption related diseases.     

Inhibitory activity of linarin on osteoclastogenesis through receptor activator of nuclear factor κB ligand-induced NF-κB pathway

Linarin, a natural flavonoid glycoside widely found in plants, has been reported to possess anti-inflammation, neuroprotection and osteogenic properties. However, its impact on osteoclast remains unclear. In the present study, the effects of linarin on osteoclastogenesis and its underlying molecular mechanisms of action were investigated. Using the culture systems of osteoclasts derived from bone marrow macrophages (BMMs), we found that linarin dose-dependently inhibited osteoclasts formation and bone resorptive activity. The Cell Counting Kit-8 test displayed that the viability of cells was not influenced by linarin at doses up to 10 μg/mL. In addition, linarin downregulated osteoclast-related genes expression, including nuclear factor of activated T cells cytoplasmic 1 (NFATc1), tartrate resistant acid phosphatase (TRAP), osteoclast-associated receptor (OSCAR) and c-Fos, as shown by quantitative real time polymerase chain reaction (RT-qPCR). Western blot analysis further showed that linarin inhibited receptor activator of nuclear factor κB ligand (RANKL)-induced nuclear factor kappa B (NF-κB) p65 and NFATc1 activity. The present findings show that linarin exerted a potent inhibitory effect on osteoclastogenesis through RANKL-induced NF-κB signaling pathway. In conclusion, the results suggest that linarin has anti-osteoclastic effects and may serve as potential modulatory agents for the prevention and treatment of bone loss-associated diseases.     

20-Hydroxyecdysone inhibits inflammation via SIRT6-mediated NF-κB signaling in endothelial cells

20-Hydroxyecdysone (20E) is known to have numerous pharmacological activities and can be used to treat diabetes and cardiovascular diseases. However, the protective effects of 20E against endothelial dysfunction and its targets remain unclear. In the present study, we revealed that 20E treatment could modulate the release of the endothelium-derived vasomotor factors NO, PGI₂ and ET-1 and suppress the expression of ACE in TNF-α-induced 3D-cultured HUVECs. In addition, 20E suppressed the expression of CD40 and promoted the expression of SIRT6 in TNF-α-induced 3D-cultured HUVECs. The cellular thermal shift assay (CETSA), drug affinity responsive target stability (DARTS) and molecular docking results demonstrated that 20E binding increased SIRT6 stability, indicating that 20E directly bound to SIRT6 in HUVECs. Further investigation of the underlying mechanism showed that 20E could upregulate SIRT6 levels and that SIRT6 knockdown abolished the regulatory effect of 20E on CD40 in TNF-α-induced HUVECs, while SIRT6 overexpression further improved the effect of 20E. Moreover, we found that 20E could reduce the acetylation of NF-κB p65 (K310) through SIRT6, but the catalytic inactive mutant SIRT6 (H133Y) did not promote the deacetylation of NF-κB p65, suggesting that the inhibitory effect of 20E on NF-κB p65 was dependent on SIRT6 deacetylase activity. Additionally, our results indicated that 20E inhibited NF-κB via SIRT6, and the expression of CD40 was increased in HUVECs treated with SIRT6 siRNA and NF-κB inhibitor. In conclusion, the present study demonstrates that 20E exerts its effect through SIRT6-mediated deacetylation of NF-κB p65 (K310) to inhibit CD40 expression in ECs, and 20E may have therapeutic potential for the treatment of cardiovascular diseases.     

Downregulation of p300/CBP-associated factor inhibits cardiomyocyte apoptosis via suppression of NF-κB pathway in ischaemia/reperfusion injury rats

Cardiomyocyte apoptosis is the main reason of cardiac injury after myocardial ischaemia-reperfusion (I/R) injury (MIRI), but the role of p300/CBP-associated factor (PCAF) on myocardial apoptosis in MIRI is unknown. The aim of this study was to investigate the main mechanism of PCAF modulating cardiomyocyte apoptosis in MIRI. The MIRI model was constructed by ligation of the rat left anterior descending coronary vessel for 30 min and reperfusion for 24 h in vivo. H9c2 cells were harvested after induced by hypoxia for 6 h and then reoxygenation for 24 h (H/R) in vitro. The RNA interference PCAF expression adenovirus was transfected into rat myocardium and H9c2 cells. The area of myocardial infarction, cardiac function, myocardial injury marker levels, apoptosis, inflammation and oxidative stress were detected respectively. Both I/R and H/R remarkably upregulated the expression of PCAF, and downregulation of PCAF significantly attenuated myocardial apoptosis, inflammation and oxidative stress caused by I/R and H/R. In addition, downregulation of PCAF inhibited the activation of NF-κB signalling pathway in cardiomyocytes undergoing H/R. Pretreatment of lipopolysaccharide, a NF-κB pathway activator, could blunt these protective effects of PCAF downregulation on myocardial apoptosis in MIRI. These results highlight that downregulation of PCAF could reduce cardiomyocyte apoptosis by inhibiting the NF-κB pathway, thereby providing protection for MIRI. Therefore, PCAF might be a promising target for protecting against cardiac dysfunction induced by MIRI.     

Sanguinarine inhibits osteoclast formation and bone resorption via suppressing RANKL-induced activation of NF-κB and ERK signaling pathways

Sanguinarine is a natural plant extract that has been supplemented in a number of gingival health products to suppress the growth of dental plaque. However, whether sanguinarine has any effect on teeth and alveolar bone health is still unclear. In this study, we demonstrated for the first time that sanguinarine could suppress osteoclastic bone resorption and osteoclast formation in a dose-dependent manner. Sanguinarine diminished the expression of osteoclast marker genes, including TRAP, cathepsin K, calcitonin receptor, DC-STAMP, V-ATPase d2, NFATc1 and c-fos. Further investigation revealed that sanguinarine attenuated RANKL-mediated IκBα phosphorylation and degradation, leading to the impairment of NF-κB signaling pathway during osteoclast differentiation. In addition, sanguinarine also affected the ERK signaling pathway by inhibiting RANKL-induced ERK phosphorylation. Collectively, this study suggested that sanguinarine has protective effects on teeth and alveolar bone health.     

Sphingosine 1-phosphate (S1P)/S1P receptor 1 signaling regulates receptor activator of NF-κB ligand (RANKL) expression in rheumatoid arthritis

Sphingosine 1-phosphate (S1P)/S1P receptor 1 (S1P1) signaling plays an important role in synovial cell proliferation and inflammatory gene expression by rheumatoid arthritis (RA) synoviocytes. The purpose of this study is to clarify the role of S1P/S1P1 signaling in the expression of receptor activator of NF-κB ligand (RANKL) in RA synoviocytes and CD4(+) T cells. We demonstrated MH7A cells, a human RA synovial cell line, and CD4(+) T cells expressed S1P1 and RANKL. Surprisingly, S1P increased RANKL expression in MH7A cells and CD4(+) T cells in a dose-dependent manner. Moreover, S1P enhanced RANKL expression induced by stimulation with TNF-α in MH7A cells and CD4(+) T cells. These effects of S1P in MH7A cells were inhibited by pretreatment with PTX, a specific Gi/Go inhibitor. These findings suggest that S1P/S1P1 signaling may play an important role in RANKL expression by MH7A cells and CD4(+) T cells. S1P/S1P1 signaling of RA synoviocytes is closely connected with synovial hyperplasia, inflammation, and RANKL-induced osteoclastogenesis in RA. Thus, regulation of S1P/S1P1 signaling may become a novel therapeutic target for RA.     

Bone morphogenetic protein 2 enhances mouse osteoclast differentiation via increased levels of receptor activator of NF-κB ligand expression in osteoblasts

1α,25-dihydroxyvitamin D₃ [1,25(OH)₂D₃] induces osteoclast formation via induction of receptor activator of NF-κB ligand (RANKL, also called TNF-related activation-induced cytokine: TRANCE) in osteoblasts. In cocultures of mouse bone marrow cells and osteoblasts, 1,25(OH)₂D₃ induced osteoclast formation in a dose-dependent manner, with maximum osteoclast formation observed at concentrations greater than 10^?9 M of 1,25(OH)₂D₃. In the presence of bone morphogenetic protein 2 (BMP-2), the maximum formation of osteoclasts was seen with lower concentrations of 1,25(OH)₂D₃ (greater than 10^?11 M), suggesting that BMP-2 enhances osteoclast formation induced by 1,25(OH)₂D₃. In addition, the expressions of RANKL mRNA and proteins were induced by 1,25(OH)₂D₃ in osteoblasts, and further upregulated by BMP-2. In mouse bone marrow cell cultures without 1,25(OH)₂D₃, BMP-2 did not enhance osteoclast differentiation induced by recombinant RANKL and macrophage colony-stimulating factor (M-CSF), indicating that BMP-2 does not target osteoclast precursors. Furthermore, BMP-2 up-regulated the expression level of vitamin D receptor (VDR) in osteoblasts. These results suggest that BMP-2 regulates mouse osteoclast differentiation via upregulation of RANKL in osteoblasts induced by 1,25(OH)₂D₃.     

Icariin inhibits RANKL-induced osteoclastogenesis via modulation of the NF-κB and MAPK signaling pathways

The receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-RANK regulatory axis is a major regulator of osteoclast differentiation and activation. Icariin, a flavonol glycoside isolated from the Epimedium herb, has been reported to prevents bone loss in ovariectomized mice and inhibits wear particle-induced osteolysis. However, the molecular mechanism through which icariin inhibits RANKL-induced osteoclastogenesis has not been fully understood. Therefore, we aimed to investigate the effects of icariin on RANKL-induced osteoclastogenesis and to elucidate the mechanism underlying this effect. Our results showed that RANKL-induced osteoclastogenesis was inhibited by icariin in bone marrow macrophages (BMMs) and RAW264.7?cells, and that this effect was due to suppression of NF-κB and mitogen-activated protein kinase (MAPK) activation. In addition, icariin inhibited F-actin ring formation and attenuated the bone resorption ability of mature osteoclasts. Collectively, our results indicate that icariin may be a promising potential candidate for the treatment of osteolytic diseases such as osteoporosis. Moreover, our findings lay the foundation for understanding and intervening in osteoclast-related diseases at the molecular level.     

Effects of receptor activator of NF-κB ligand gene silencing on the human osteoblast-like MG63 cells

The osteoprotegerin (OPG)/receptor activator of nuclear factor-κB ligand (RANKL)/receptor activator of NF-κB (RANK) system plays an important role in the pathogenesis of metabolic bone diseases. This study is aimed to investigate effects and mechanisms of RANKL gene silencing on the function of human osteoblast-like MG63 cells by RNA interference using a lentivirus-based small hairpin RNA (vshRNA) delivery system. After RANKL-specific vshRNAs were designed, constructed and transfected into MG63 cells, changes in the expression levels of RANKL mRNA and protein were determined by Western blot and RT-PCR, respectively; changes in cell activity and cell cycle distribution were examined by thiazolyl blue tetrazolium bromide assay and flow cytometry. The expression levels of RANKL mRNA and protein in MG63 cells were reduced by transferring RANKL-specific vshRNAs. Compared to cells infected with negative control virus, the proliferation of cells infected with the recombinant virus was more likely to be inhibited. Furthermore, the cell cycle of MG63 was altered, with the number of G1 phase cells decreasing significantly (P < 0.05). RANKL-specific vshRNAs can significantly inhibit the expression of the target gene in MG63 cells. RANKL gene silencing can inhibit the proliferation and alter the cell cycle of MG63 cells. Our findings suggest that RANKL might play an important role in the regulation of growth and cell cycle of MG63 cells.     

Recombinant DNA cloning of the active region of the receptor activator of NF-κB ligand (RANKL) gene and its role in osteoclastogenesis

Osteopetrosis belongs to a group of rare genetic diseases typically treated with bone marrow transplantation. This approach is not effective in a recently identified form of the disease caused by mutations in the receptor activator of NF-κB ligand (RANKL) gene. In these patients, replacement therapy and RANKL delivery may be a more valid approach than transplantation. Here, we describe the construction of a recombinant gene encoding regions of RANKL (rRANKL), including the biologically active regional loop sequence. We present detailed methods for the cloning, expression, and purification of the recombinant protein. The activity of rRANKL including the active region was assessed in vitro and mature osteoclast generation was evaluated in vivo using a mouse model. We provide a proof of concept for the therapeutic potential of full-length and selected active regions of rRANKL in the treatment of osteopetrosis, warranting clinical assessment.     

PSMB4 inhibits cardiomyocyte apoptosis via activating NF-κB signaling pathway during myocardial ischemia/reperfusion injury

Journal of Molecular Histology - Myocardial ischemia/reperfusion (I/R) injury induces cardiomyocyte apoptosis to deteriorate heart function. Thus, how to inhibit cardiomyocyte apoptosis is the...     

Centipeda minima extract exerts antineuroinflammatory effects via the inhibition of NF-κB signaling pathway

BackgroundCentipeda minima (L.) A.Br. (C. minima) has been used in traditional Chinese herbal medicine to treat nasal allergy, diarrhea, asthma and malaria for centuries. Recent pharmacological studies have demonstrated that the ethanol extract of C. minima (ECM) and several active components possess anti-bacterial, anti-arthritis and anti-inflammatory properties. However, the effects of ECM on neuroinflammation and the underlying mechanisms have never been reported.PurposeThe study aimed to examine the potential inhibitory effects of ECM on neuroinflammation and illustrate the underlying mechanisms.MethodsHigh performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was performed to qualify the major components of ECM; BV2 and primary microglial cells were used to examine the anti-inflammatory activity of ECM in vitro. To evaluate the anti-inflammatory effects of ECM in vivo, the mice were orally administrated with ECM (100, 200 mg•kg⁻¹•d⁻¹) for 2 days before cotreatment with LPS (2 mg•kg⁻¹•d⁻¹, ip) for an additional 3 days. The mice were sacrificed the day after the last treatment and the hippocampus was dissected for further experiments. The expression of inflammatory proteins and the activation of microglia were respectively detected by real-time PCR, ELISA, Western blotting and immunofluorescence.ResultsHPLC-MS/MS analysis confirmed and quantified seven chemicals in ECM. In BV2 and primary microglial cells, ECM inhibited the LPS-induced production of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), thus protecting HT22 neuronal cells from inflammatory damage. Furthermore, ECM inhibited the LPS-induced activation of NF-κB signaling pathway and subsequently attenuated the induction of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX2), NADPH oxidase 2 (NOX2) and NADPH oxidase 4 (NOX4), leading to the decreased production of nitrite oxide, prostaglandin E₂ (PGE₂) and reactive oxygen species (ROS). In an LPS-induced neuroinflammatory mouse model, ECM was found to exert anti-inflammatory activity by decreasing the production of proinflammatory mediators, inhibiting the phosphorylation of NF-κB, and reducing the expression of COX2, iNOS, NOX2 and NOX4 in the hippocampal tissue. Moreover, LPS-induced microglial activation was markedly attenuated in the hippocampus, while ECM at a high dose possesses a stronger anti-inflammatory activity than the positive drug dexamethansone (DEX).ConclusionThese findings demonstrate that ECM exerts antineuroinflammatory effects via attenuating the activation of NF-κB signaling pathway and inhibiting the production of proinflammatory mediators both in vitro and in vivo. C. minima might become a novel phytomedicine to treat neuroinflammatory diseases.     

Obovatol attenuates LPS-induced memory impairments in mice via inhibition of NF-κB signaling pathway

Neuroinflammation and accumulation of β-amyloid are critical pathogenic mechanisms of Alzheimer’s disease (AD). In the previous study, we have shown that systemic lipopolysaccharide (LPS) caused neuroinflammation with concomitant increase in β-amyloid and memory impairments in mice. In an attempt to investigate anti-neuroinflammatory properties of obovatol isolated from Magnolia obovata, we administered obovatol (0.2, 0.5 and 1.0 mg/kg/day, p.o.) to animals for 21 days before injection of LPS (0.25 mg/kg, i.p.). We found that obovatol dose-dependently attenuates LPS-induced memory deficit in the Morris water maze and passive avoidance tasks. Consistent with the results of memory tasks, the compound prevented LPS-induced increases in Aβ_1-42 formation, β- and γ-secretases activities and levels of amyloid precursor protein, neuronal β-secretase 1 (BACE1), and C99 (a product of BACE1) in the cortex and hippocampus. The LPS-mediated neuroinflammation as determined by Western blots and immunostainings was significantly ameliorated by the compound. Furthermore, LPS-induced nuclear factor (NF)-κB DNA binding activity was drastically abolished by obovatol as shown by the electrophoretic mobility shift assay. The anti-neuroinflammation and anti-amyloidogenesis by obovatol were replicated in in vitro studies. These results show that obovatol mitigates LPS-induced amyloidogenesis and memory impairment via inhibiting NF-κB signal pathway, suggesting that the compound might be plausible therapeutic intervention for neuroinflammation-related diseases such as AD.     

Galectin-3 deficiency protects lipopolysaccharide-induced chondrocytes injury via regulation of TLR4 and PPAR-γ-mediated NF-κB signaling pathway

The aim of the present study was to identify the functional role of galectin-3 (Gal-3) in lipopolysaccharide (LPS)-induced injury in ATDC5 cells and to explore the probable molecular mechanisms. Here, we identified that LPS is sufficient to enhance the expression of Gal-3 in ATDC5 cells. In addition, repression of Gal-3 obviously impeded LPS-stimulated inflammation damage as exemplified by a reduction in the release of inflammatory mediators interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, as well as the production of nitric oxide and prostaglandin E2 (PGE2) concomitant with the downregulation of matrix metalloproteinases (MMP)-13 and MMP-3 expression in ATDC5 cells after LPS administration. Moreover, ablation of Gal-3 dramatically augmented cell ability and attenuated cell apoptosis accompanied by an increase in the expression of antiapoptotic protein Bcl-2 and a decrease in the expression of proapoptotic protein Bax and caspase-3 in ATDC5 cells subjected with LPS. Importantly, we observed that forced expression of TLR4 or blocked PPAR-γ with the antagonist GW9662 effectively abolished Gal-3 inhibition–mediated anti-inflammatory and antiapoptosis effects triggered by LPS. Mechanistically, depletion of Gal-3 prevents the NF-κB signaling pathway. Taken together, these findings indicated that the absence of Gal-3 exerted chondroprotective properties dependent on TLR4 and PPAR-γ-mediated NF-κB signaling, indicating that Gal-3 functions as a protector in the development and progression of osteoarthritis.     

Artesunate inhibits Sjögren's syndrome-like autoimmune responses and BAFF-induced B cell hyperactivation via TRAF6-mediated NF-κB signaling

BackgroundHyperactivation of B cells by activators has been demonstrated to play a central role in the pathogenesis of Sjögren's syndrome (SS). In this study, we found that artesunate (ART) can attenuate BAFF-induced B cell hyperactivation and SS-like symptoms in NOD/Ltj mice.PurposeTo determine the efficacy of ART in attenuating SS-like symptoms in vivo and explore the underlying mechanism in vitro.Study designART was intragastrically injected into SS-like NOD/Ltj mice. The cytokine hsBAFF was used to activate Raji and Daudi B cells to mimic B cell hyperactivation in vitro.MethodsThe efficacy of ART in inhibiting SS progression was studied in NOD/Ltj mice. Salivary flow rate, the number of lymphocytic infiltration foci, the level of autoantibodies and the extent of B cell infiltration were measured in the indicated groups. CCK-8 assays, flow cytometry-based EdU staining and Annexin V/PI staining were also used to detect the effect of ART on the survival and proliferation mechanism in BAFF-induced Raji and Daudi cells. Further studies determined that TRAF6 degradation is a potential mechanism by which ART determines B cell fate.ResultsTreatment with ART inhibited lymphocytic foci formation, B cell infiltration and autoantibody secretion in SS-like NOD/Ltj mice. In vitro assay results indicated that ART effectively inhibited BAFF-induced viability, survival and proliferation of neoplastic B cells. Mechanistically, ART targeted BAFF-activated NFκB by regulating the proteasome-mediated degradation of TRAF6 in Raji and Daudi cells.ConclusionART ameliorated murine SS-like symptoms and regulated TRAF6-NFκB signaling, thus determining survival and proliferation of B cells.     

Puerarin concurrently stimulates osteoprotegerin and inhibits receptor activator of NF-κB ligand (RANKL) and interleukin-6 production in human osteoblastic MG-63 cells

Puerarin, a daidzein-8-C-glucoside, is the major isoflavone glycoside found in the Chinese herb radix of Pueraria lobata (Willd.) Ohwi, and has received increasing attention because of its possible role in the prevention of osteoporosis. In our previous studies, puerarin reduced the bone resorption of osteoclasts and promoted long bone growth in fetal mouse in vitro. Further study confirmed that puerarin stimulated proliferation and differentiation of osteoblasts in rat. However, the mechanisms underlying its actions on human bone cells have remained largely unknown. Here we show that puerarin concurrently stimulates osteoprotegerin (OPG) and inhibits receptor activator of nuclear factor-κB ligand (RANKL) and Interleukin-6 (IL-6) production by human osteoblastic MG-63 cells containing two estrogen receptor (ER) isotypes. Treatment with the ER antagonist ICI 182,780 abrogates the above actions of puerarin on osteoblast-derived cells. Using small interfering double-stranded RNAs technology, we further demonstrate that the effects of puerarin on OPG and RANKL expression are mediated by both ERα and ERβ but those on IL-6 production primarily by ERα. Moreover, we demonstrate that puerarin may promote activation of the classic estrogen response element (ERE) pathway through increasing ERα, ERβ and steroid hormone receptor coactivator (SRC)-1 expression. Therefore, puerarin will be a promising agent that prevents or retards osteoporosis.