2-cyclohexylamino-5,8-dimethoxy-1,4-naphthoquinone inhibits LPS-induced BV2 microglial activation through MAPK/NF-kB signaling pathways

Protective effects of MNQ against Lipopolysaccharide-induced inflammatory damage in bovine ovarian follicular granulosa cells in Vitro

Inflammation of the reproductive tract in dairy cows lead to functional disorders of follicular granulosa cells (GCs) in mammalian ovaries resulting in infertility and serious losses to the livestock industry. Lipopolysaccharide (LPS) can induce an inflammatory response in follicular granulosa cells in vitro. The aim of this study was to investigate the cellular regulatory mechanism of MNQ (2-methoxy-1,4-naphthoquinone) on eliminating the inflammatory response and restoring normal functions for bovine ovarian follicular GCs cultured in vitro exposed to LPS. The cytotoxicity of MNQ and LPS on GCs were detected by MTT method to determine the safe concentration. The relative expression of inflammatory factors and steroid synthesis-related genes were detected by qRT-PCR. The concentration of steroid hormones in the culture broth were detected by ELISA. Differential gene expressions were analyzed by RNA-seq. There were no toxic effects on GCs at MNQ and LPS concentrations of less than 3 µM and 10 µg/mL, respectively and treated in 12 h. The relative expressions of IL-6, IL-1β and TNF-α were significantly higher in the LPS group compared with the CK group when GCs cultured in vitro were treated with the above concentrations and times (P < 0.05), but significantly lower in the MNQ+LPS group compared with the LPS group (P < 0.05). The levels of E₂ and P₄ in the culture solution were significantly reduced in the LPS group compared to the CK group (P < 0.05), and restored in the MNQ+LPS group. The relative expressions of CYP19A1, CYP11A1, 3β-HSD, and STAR were significantly decreased in the LPS group compared with the CK group (P < 0.05), while the MNQ+LPS group also recovered to some extent. There were 407 differential genes shared by LPS vs CK and MNQ+LPS vs LPS by RNA-seq analysis, which were mainly enriched in steroid biosynthesis and TNF signaling pathway. We screened 10 genes for analysis and found consistent results for RNA-seq and qRT-PCR. In this study, we confirmed the protective effect of MNQ, an extract from Impatiens balsamina L, on LPS-induced inflammatory responses in bovine follicular granulosa cells in vitro as well as functional damage, and acted through steroid biosynthesis and TNF signaling pathways.

6-methoxyflavone suppresses neuroinflammation in lipopolysaccharide- stimulated microglia through the inhibition of TLR4/MyD88/p38 MAPK/NF-κB dependent pathways and the activation of HO-1/NQO-1 signaling

BACKGROUND

Microglia-related neuroinflammation is associated with a variety of neurodegenerative diseases. Flavonoids have demonstrated different pharmacological effects, such as antioxidation, neuroprotection and anti-inflammation However, the effect of flavonoid 6-methoxyflavone (6-MeOF) on microglia-mediated neuroinflammation remain unknown.

PURPOSE

The current study aim to study the antineuroinflammatory effects of 6-MeOF in lipopolysaccharide- (LPS-) induced microglia in vitro and in vivo.

METHODS

Pretreatment of BV2 microglia cells with 6-MeOF for 1 h then stimulated with LPS (100 ng/ml) for 24 h. The expression levels of pro-inflammatory factors, NO and reactive oxygen species (ROS) were performed by the enzyme-linked immunosorbent assay (ELISA), Griess assay and flow cytometry. Western blotting was used to assess MAPK, NF-κB signal transducer and antioxidant enzymes-related proteins. Analysis of ROS and microglial morphology was confirmed in the zebrafish and mice brain, respectively.

RESULTS

Our results demonstrated that 6-MeOF dose-dependently prevent cell death and decreased the levels of pro-inflammatory mediators in LPS-stimulated BV2 microglia cells. Phosphorylated NF-κB/IκB and TLR4/MyD88/p38 MAPK/JNK proteins after exposure to 6-MeOF was suppressed in LPS-activated BV-2 microglial cells. 6-MeOF also presented antioxidant activity by reduction of NO, ROS, iNOS and COX-2 and the induction of the level of HO-1 and NQO1 expressions in LPS-activated BV2 microglial cells. Furthermore, we demonstrated that 6-MeOF inhibited LPS-induced NO generation in an experimental zebrafish model and prevent the LPS-induced microgliosis in the prefrontal cortex and substantia nigra of mice.

CONCLUSION

These results explored that 6-MeOF possesses potential as anti-inflammatory and anti-oxidant agents against microglia-associated neuroinflammatory disorders.

Walnut peptide WEKPPVSH in alleviating oxidative stress and inflammation in lipopolysaccharide-activated BV-2 microglia via the Nrf2/HO-1 and NF-κB/p38 MAPK pathways

The peptide WEKPPVSH from walnut protein hydrolyzate was used to evaluate the antioxidant and anti-inflammatory protective effect on lipopolysaccharide (LPS)-activated BV-2 microglia and its possible mechanism. The results indicated that WEKPPVSH significantly decreased nitric oxide (NO) and reactive oxygen species (ROS) generation in a dose-dependent manner, and significantly up-regulated superoxide dismutase and catalase activities (P < 0.01). Results of enzyme-linked immunosorbent assay (ELISA) showed that WEKPPVSH significantly mitigated the secretion of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) (P < 0.01). Immunofluorescence analysis exhibited that WEKPPVSH down-regulated p65 translocation to the cell nucleus. Western blotting showed that WEKPPVSH up-regulated the expression of nuclear factor erythroid 2-related factor (Nrf2) and heme oxygenase-1 (HO-1), and down-regulated the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), p-IκB/IκB, p-p65/p65 and p-p38/p38. In summary, WEKPPVSH might protect against oxidative stress and inflammation in LPS-stimulated BV-2 microglia by enhancing the Nrf2/HO-1 signaling pathway and blocking the nuclear factor-κB/p38 mitogen - activated protein kinase (NF-κB/p38 MAPK) signaling pathway. The results provided an experimental basis for the research and development of walnut peptide products.

The compound 2-benzylthio-5,8-dimethoxynaphthalene-1,4-dione leads to apoptotic cell death by increasing the cellular reactive oxygen species levels in Ras-mutated liver cancer cells

The aim of the present study was to verify the pro-apoptotic anticancer potential of several 5,8-dimethoxy-1,4-phthoquinone (DMNQ) derivatives in Ras-mediated tumorigenesis. MTT assays were used to detect cellular viability and flow cytometry was performed to assess intracellular reactive oxygen species (ROS) levels and apoptosis. The expression levels of proteins were detected via western blotting. Among the 12 newly synthesized DMNQ derivatives, 2-benzylthio-5,8-dimethoxynaphthalene-1,4-dione (BZNQ; component #1) significantly reduced cell viability both in mouse NIH3T3 embryonic fibroblasts cells (NC) and H-Ras^G12V transfected mouse NIH3T3 embryonic fibroblasts cells (NR). Moreover, BZNQ resulted in increased cytotoxic sensitivity in Ras-mutant transfected cells. Furthermore, the reactive oxygen species (ROS) levels in H-Ras^G12V transfected HepG2 liver cancer cells (HR) were significantly higher compared with the levels in HepG2 liver cancer cells (HC) following BZNQ treatment, which further resulted in increased cellular apoptosis. Eliminating cellular ROS using an ROS scavenger N-acetyl-L-cysteine markedly reversed BZNQ-induced cellular ROS accumulation and cell apoptosis in HC and HR cells. Western blotting results revealed that BZNQ significantly downregulated H-Ras protein expression and inhibited the Ras-mediated downstream signaling pathways such as protein kinase B, extracellular signal-related kinase and glycogen synthase kinase phosphorylation and β-catenin protein expression. These results indicated that the novel DMNQ derivative BZNQ may be a therapeutic drug for Ras-mediated liver tumorigenesis. The results of the current study suggest that BZNQ exerts its effect by downregulating H-Ras protein expression and Ras-mediated signaling pathways.

Semisynthetic quercetin-quinone mitigates BV-2 microglia activation through modulation of Nrf2 pathway

During brain ageing, microglia, the resident immune cells of the CNS, are immunologically activated and contribute to neuroinflammation, a vicious cycle that supports development of neurological disorders. Therapeutic approaches focus mainly on downregulation of their pro-inflammatory activated state that is associated with health benefits. Electrophilic compounds, such as natural quinones and their reduced pro-electrophilic precursors, flavonoids, represent a wide group of diverse substances with important biological effects. They can cause considerable cytotoxicity when used at higher dosages, but on the other hand, they have versatile health benefits at lower dosages. In this study, we investigated the cytotoxicity and prooxidant profile of synthetic conjugate of two electrophilic compounds, quercetin and 1,4-naphthoquinone, 4'-O-(2-chloro-1,4-naphthoquinone-3-yloxy) quercetin (CHNQ), and its attenuation of inflammatory responses and modulation of Nrf2 pathway in BV-2 microglial cells. CHNQ showed higher cytotoxicity than its precursors, accompanied by promotion of production of reactive oxygen species along with G2/M cell cycle arrest at higher concentrations tested. Nevertheless, at a lower non-toxic concentration, CHNQ, more significantly than did its precursors, downregulated LPS-stimulated microglia cells as documented by decreased iNOS, COX-2 and TNFα protein levels. Moreover, CHNQ most effectively upregulated expression of phase II antioxidant enzyme HO-1 and β5 subunit of constitutive proteasome. The enhanced anti-inflammatory effect of CHNQ was accompanied by prominent increase in cytosolic expression of Nrf2 and c-Jun, however, induction effect on nuclear Nrf2 translocation was comparable to QUER. Moreover, a conditioned medium from activated BV-2 cells co-treated with quercetin and CHNQ maintained viability of neuron-like PC12 cells. The compounds tested did not show any disturbance of phagocytosis of live or dead PC12 cells. The present experimental data predict a preventive and therapeutic potential of semisynthetic derivative CHNQ in ageing and related pathologies, mediated by activation of proteins of the antioxidant response.

MsrA Suppresses Inflammatory Activation of Microglia and Oxidative Stress to Prevent Demyelination via Inhibition of the NOX2-MAPKs/NF-κB Signaling Pathway

Introduction

Demyelination causes neurological deficits involving visual, motor, sensory symptoms. Deregulation of several enzymes has been identified in demyelination, which holds potential for the development of treatment strategies for demyelination. However, the specific effect of methionine sulfoxide reductase A (MsrA) on demyelination remains unclear. Hence, this study aims to explore the effect of MsrA on oxidative stress and inflammatory response of microglia in demyelination.

Methods

Initially, we established a mouse model with demyelination induced by cuprizone and a cell model provoked by lipopolysaccharide (LPS). The expression of MsrA in wild-type (WT) and MsrA-knockout (MsrA^-/-) mice were determined by RT-qPCR and Western blot analysis. In order to further explore the function of MsrA on inflammatory response, and oxidative stress in demyelination, we detected the expression of microglia marker Iba1, inflammatory factors TNF-α and IL-1β and intracellular reactive oxygen species (ROS), superoxide dismutase (SOD) activity, as well as expression of the NOX2-MAPKs/NF-κB signaling pathway-related genes in MsrA^-/- mice and LPS-induced microglia following different treatments.

Results

MsrA expression was downregulated in MsrA^-/- mice. MsrA silencing was shown to produce severely injured motor coordination, increased expressions of Iba1, TNF-α, IL-1β, ROS and NOX2, and extent of ERK, p38, IκBα, and p65 phosphorylation, but reduced SOD activity. Conjointly, our study suggests that Tat-MsrA fusion protein can prevent the cellular inflammatory response and subsequent demyelination through negative regulation of the NOX2-MAPKs/NF-κB signaling pathway.

Conclusion

Our data provide a profound insight on the role of endogenous antioxidative defense systems such as MsrA in controlling microglial function.

2-(4-methoxyphenylthio)-5,8-dimethoxy-1,4-naphthoquinone induces apoptosis via ROS-mediated MAPK and STAT3 signaling pathway in human gastric cancer cells

The 1,4-naphthoquinones and their derivatives have garnered great interest due to their antitumor pharmacological properties in various cancers; however, their clinical application is limited by side effects. In this study, to reduce side effects and improve therapeutic efficacy, a novel 1,4-naphthoquinone derivative-2-(4-methoxyphenylthio)-5,8-dimethoxy-1,4-naphthoquinone (MPTDMNQ) was synthesized. We investigated the effects and underlying mechanisms of MPTDMNQ on cell viability, apoptosis, and reactive oxygen species (ROS) generation in human gastric cancer cells. Our results showed that MPTDMNQ decreased cell viability in nine human gastric cancer cell lines. MPTDMNQ significantly induced apoptosis accompanied by the accumulation of ROS in GC cells. However, pre-treatment with the ROS scavenger N-acetyl-L-cysteine (NAC) attenuated the MPTDMNQ-induced apoptosis. Moreover, MPTDMNQ decreased the phosphorylation levels of extracellular signal-regulated kinase (ERK) and signal transducer and activator of transcription 3 (STAT3); and increased the phosphorylation levels of c-Jun N-terminal kinase (JNK) and p38 kinase. However, phosphorylation was inhibited by NAC and a mitogen-activated protein kinase (MAPK) inhibitor. These findings showed that MPTDMNQ induced AGS cell apoptosis via ROS-mediated MAPK and STAT3 signaling pathways. Thus, MPTDMNQ may be a promising candidate for treating gastric cancer.

Officinalins A and B, a pair of C23 terpenoid epimers with a tetracyclic 6/7/5/5 system from Salvia officinalis

Officinalins A (1) and B (2), a pair of 6/7/5/5 tetracyclic C₂₃ terpenoid epimers with a unique tetracycline-[9.6.0.0^3,8.0^12,16]-heptadecane core and a peroxide bridge, were isolated from the leaves of Salvia officinalis.

The compound 2-(naphthalene-2-thio)-5,8-dimethoxy-1,4-naphthoquinone induces apoptosis via reactive oxygen species-regulated mitogen-activated protein kinase, protein kinase B, and signal transducer and activator of transcription 3 signaling in human gastric cancer cells

Hit, Lead & Candidate Discovery It is reported that 1,4-naphthoquinones and their derivatives have potent antitumor activity in various cancers, although their clinical application is limited by observed side effects. To improve the therapeutic efficacy of naphthoquinones in the treatment of cancer and to reduce side effects, we synthesized a novel naphthoquinone derivative, 2-(naphthalene-2-thio)-5,8-dimethoxy-1,4-naphthoquinone (NTDMNQ). In this study, we explored the effects of NTDMNQ on apoptosis in gastric cancer cells with a focus on reactive oxygen species (ROS) production. Our results demonstrated that NTDMNQ exhibited the cytotoxic effects on gastric cancer cells in a dose-dependent manner. NTDMNQ significantly induced mitochondrial-related apoptosis in AGS cells and increased the accumulation of ROS. However, pre-treatment with N-acetyl-L-cysteine (NAC), an ROS scavenger, inhibited the NTDMNQ-induced apoptosis. In addition, NTDMNQ increased the phosphorylation of p38 kinase and c-Jun N-terminal kinase (JNK) and decreased the phosphorylation of extracellular signal-regulated kinase (ERK), protein kinase B (Akt), and Signal Transducer and Activator of Transcription 3 (STAT3); these effects were blocked by mitogen-activated protein kinase (MAPK) inhibitor and NAC. Taken together, the present findings indicate that NTDMNQ-induced gastric cancer cell apoptosis via ROS-mediated regulation of the MAPK, Akt, and STAT3 signaling pathways. Therefore, NTDMNQ may be a potential treatment for gastric cancer as well as other tumor types.

Cancer stem cells and epithelial-mesenchymal transition in urothelial carcinoma: Possible pathways and potential therapeutic approaches

There is growing evidence of the presence of cancer stem cells in urothelial carcinoma. Cancer stem cells have the ability to self-renew and to differentiate into all cell types of the original heterogeneous tumor. A panel of diverse cancer stem cell markers might be suitable for simulation studies of urothelial cancer stem cells and for the development of optimized treatment protocols. The present review focuses on the advances in recognizing the markers of urothelial cancer stem cells and possible therapeutic targets. The commonly reported markers and pathways that were evaluated include CD44, CD133, ALDH1, SOX2 & SOX4, BMI1, EZH1, PD-L1, MAGE-A3, COX2/PGE2/STAT3, AR, and autophagy. Studies on the epithelial-mesenchymal transition-related pathways (Shh, Wnt/β-catenin, Notch, PI3K/Akt, TGF-β, miRNA) are also reviewed. Most of these markers were recognized through the expression patterns of cancer stem cell-rich side populations. Their regulative role in the development and differentiation of urothelial cancer stem cells was confirmed in vitro by functional analyses (e.g. cell migration, colony formation, sphere formation), and in vivo in xenograft experiments. Although a small number of these pathways are targeted by currently available drugs or drugs that are the currently being tested in clinical trials, a clear treatment approach has not been developed for most pathways. A greater understanding of the mechanisms that control the proliferation and differentiation of cancer stem cells is expected to lead to improvements in targeted therapy.