Inhibition Of MAPK Phosphorylation Research Articles

Blueberry stem extract and stem active components prevent blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro.

Blue light causes retinal damage that can lead to ocular diseases such as age-related macular degeneration. In this study, we determined the protective effect of blueberry stem extract (BStEx) and active components on blue light-emitting diode (LED) light-induced retinal photoreceptor cell damage in vitro. Photoreceptor cells cultured in the presence of BStEx or components were exposed to blue light to induce cell damage. BStEx, fractions of BStEx containing proanthocyanidins, chlorogenic acid, catechin, and epicatechin prevented the cell damage and/or inhibited the generation of reactive oxygen species (ROS). Furthermore, BStEx reduced apoptosis and cell death, and inhibited the phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase leading to cellular apoptosis induced by blue light exposure. These findings suggest that BStEx and components exert a protective effect against blue light-induced photoreceptor cell damage through the inhibition of MAPK phosphorylation and ROS production.

Protective Effects of Withagenin A Diglucoside from Indian Ginseng (Withania somnifera) against Human Dermal Fibroblast Damaged by TNF-α Stimulation.

Human skin is constructed with many proteins such as collagen and elastin. Collagen and elastin play a key role in providing strength and elasticity to the human skin and body. However, damage to collagen causes various symptoms such as wrinkles and freckles, which suggests that they are important to maintain skin condition. Extrinsic or intrinsic skin aging produces an excess of skin destructive factors such as tumor necrosis factor (TNF)-α, which is a major mediator of the aging process. In aged skin, TNF-α provokes the generation of intracellular ROS (reactive oxygen species). It triggers the excessive secretion of MMP-1, which is a collagen-degrading enzyme that causes the collapse of skin collagen. Therefore, we aimed to search for a natural-product-derived candidate that inhibits the skin damage caused by TNF-α in human dermal fibroblasts. In this study, the protective effect of withagenin A diglucoside (WAD) identified from Withania somnifera against TNF-α-stimulated human dermal fibroblasts is investigated. W. somnifera (Solanaceae), well-known as 'ashwagandha', is an Ayurvedic medicinal plant useful for promoting health and longevity. Our experimental results reveal that WAD from W. somnifera suppresses the generation of intercellular ROS. Suppressing intracellular ROS generation inhibits MMP-1 secretion and the collapse of type 1 collagen. The effect of WAD is shown to depend on the inhibition of MAPK phosphorylation, Akt phosphorylation, c-Jun phosphorylation, COX-2 expression, and NF-κB phosphorylation. Further, WAD-depressed expression of the pro-inflammatory cytokines IL-6 and IL-8 triggers various inflammatory reactions in human skin. These findings suggest that WAD has protective effects against skin damage. Accordingly, our study provides experimental evidence that WAD can be a potential agent that can be applied in various industrial fields, such as cosmetics and pharmaceuticals related to skin aging.

Robust Activity of Avapritinib, Potent and Highly Selective Inhibitor of Mutated KIT, in Patient-derived Xenograft Models of Gastrointestinal Stromal Tumors.

Gastrointestinal stromal tumors (GIST) are commonly treated with tyrosine kinase inhibitors (TKI). The majority of patients with advanced GIST ultimately become resistant to TKI due to acquisition of secondary KIT mutations, whereas primary resistance is mainly caused by PDGFRA p.D842V mutation. We tested the activity of avapritinib, a potent and highly selective inhibitor of mutated KIT and PDGFRA, in three patient-derived xenograft (PDX) GIST models carrying different KIT mutations, with differential sensitivity to standard TKI.Experimental Design: NMRI nu/nu mice (n = 93) were transplanted with human GIST xenografts with KIT exon 11+17 (UZLX-GIST9 KIT 11+17 ), exon 11 (UZLX-GIST3 KIT 11 ), or exon 9 (UZLX-GIST2B KIT9 ) mutations, respectively. We compared avapritinib (10 and 30 mg/kg/once daily) versus vehicle, imatinib (50 mg/kg/bid) or regorafenib (30 mg/kg/once daily; UZLX-GIST9 KIT11+17 ); avapritinib (10, 30, 100 mg/kg/once daily) versus vehicle or imatinib [UZLX-GIST3 KIT11 ]; and avapritinib (10, 30, 60 mg/kg/once daily) versus vehicle, imatinib (50, 100 mg/kg/twice daily), or sunitinib (40 mg/kg/once daily; UZLX-GIST2B KIT9 ). In all models, avapritinib resulted in reduction of tumor volume, significant inhibition of proliferation, and reduced KIT signaling. In two models, avapritinib led to remarkable histologic responses, increase in apoptosis, and inhibition of MAPK-phosphorylation. Avapritinib showed superior (UZLX-GIST9 KIT 11+17 and -GIST2B KIT 9 ) or equal (UZLX-GIST3 KIT 11 ) antitumor activity to the standard dose of imatinib. In UZLX-GIST9 KIT 11+17 , the antitumor effects of avapritinib were significantly better than with imatinib or regorafenib. Avapritinib has significant antitumor activity in GIST PDX models characterized by different KIT mutations and sensitivity to established TKI. These data provide strong support for the ongoing clinical trials with avapritinib in patients with GIST (NCT02508532, NCT03465722).

Hepatoprotective effects of lactic acid-fermented garlic extract against acetaminophen-induced acute liver injury in rats.

The aim of the present study was to investigate the protective effect of fermented garlic extract by lactic acid bacteria (LAFGE) against acetaminophen (AAP)-induced acute liver injury in rats. Here we demonstrated that rats treated with LAFGE exhibit resistance to AAP-induced liver injury accompanied by lowered plasma alanine amino transferase levels and decreased proinflammatory responses. This function of LAFGE is linked to its capacity of suppressing AAP-induced apoptosis in the liver, partly via the inhibition of MAPK phosphorylation as well as down-regulation of p53. Our findings reveal that LAFGE modulates the signaling pathways involved in hepatic apoptosis through cellular redox control, as indicated by the inhibition of lipid peroxidation, glutathione and ATP depletion, and the elevation of antioxidant enzyme activities. Taken together, these findings indicate that LAFGE ameliorates AAP-induced liver injury by preventing oxidative stress-mediated apoptosis, thereby establishing LAFGE as a potential supplement in the treatment of AAP-induced liver injury.

Anti-inflammatory activity on mice of extract of Ganoderma lucidum grown on rice via modulation of MAPK and NF-κB pathways

Ganoderma lucidum is a popular medicinal mushroom with anti-inflammatory potential. In the present study, the aim was to determine the anti-inflammatory effect and mode of action of G. lucidum grown on germinated brown rice (GLBR) in a mouse model of colitis. It was shown that GLBR suppressed the production of nitric oxide (NO) and prostaglandin E2 (PGE2) in lipopolysaccharide (LPS)-stimulated macrophages and decreased the expression of COX-2, TNF-α, iNOS, IL-1β, IL-6, and IL-10 mRNAs. GLBR also inhibited activation of p38, ERK, JNK, MAPKs, and nuclear factor kappa-B (NF-κB). In a mouse model of colitis, colonic mucosal injury was evaluated using macroscopic, biochemical, and histopathological testing. Disease activity index (DAI), macroscopic score, and histological score significantly decreased upon GLBR treatment. Moreover, immunofluorescence studies indicated that DSS activates nuclear translocation of NF-κB in colon tissue, which is attenuated by GLBR extract. These findings suggest that GLBR is protective against colitis via inhibition of MAPK phosphorylation and NF-κB activation.

The inhibitory effect of sinigrin on the production of inflammatory mediators induced by lipopolysaccharide in RAW 264.7 macrophages (1056.5)

Sinigrin (2‐propenylglucosinolate) is a biochemical nutrient found naturally in some plants of the Brassicaceae family such as broccoli, Brussels sprouts. Recent studies showed that sinigrin affect the preventing of cancer in preclinical or clinical trials for cancer chemoprevention. However, anti‐inflammatory effect of sinigrin was unknown. In the present study, we examined the effects of sinigrin on the production of inflammatory mediators in lipopolysaccharide (LPS)‐activated RAW 264.7 macrophages. The cell viability was determined by MTT assay. We investigated the anti‐inflammatory effects of sinigrin on Nitrite Oxide (NO) and pro‐inflammatory cytokine production by colorimetric assay and ELISA assay, respectively. We also examined the expression of MAPK, NLRP‐3 and p65 by Western blot. The results showed that NO production was not reduced by sinigirn.Whereas, sinigrin inhibited the levels of tumor necrosis factor‐ α (TNF‐α) and interleukin‐6 (IL‐6). Sinigrin blocked phosphorylation of JNK and p38, but not that of ERK. In addition, sinigrin treatment significantly suppressed the expression of p65 and NLRP‐3 compared with the control. These finding suggest that sinigrin has an anti‐inflammatory effects, which may result from inhibition of MAPK phosphorylation, and the expression of NLRP‐3 and p65, thereby decreasing the production of pro‐inflammatory mediators.

Melatonin inhibits MUC5AC production via suppression of MAPK signaling in human airway epithelial cells

Mucus acts as a primary defense system in the airway against various stimuli. However, excess mucus production causes a reduction in lung function via limitation of the airflow in the airway of patients suffering from asthma or chronic obstructive pulmonary disease (COPD). In this study, we evaluated the effects of melatonin on the production of MUC5AC, a major constituent of the mucin that is secreted from the airway, using epidermal growth factor (EGF)-stimulated NCI-H292 cells, a human mucoepidermoid carcinoma cell line, and an ovalbumin (OVA)-induced asthma murine model. Melatonin treatment significantly reduced the mRNA and protein levels of MUC5AC and reduced interleukin (IL)-6 production in EGF-stimulated H292 cells. Melatonin markedly decreased the phosphorylation of MAPKs, including ERK1/2, JNK, and p-38, induced by EGF stimulation. These findings were consistent with the results using MAPK inhibitors. Particularly, co-treatment with melatonin and a MAPK inhibitor more effectively suppressed MAPK phosphorylation than treatment with a MAPK inhibitor alone, which resulted in a reduction in MUC5AC expression. In the asthma murine model, melatonin-treated mice exhibited a marked reduction in MUC5AC expression in the airway compared with the OVA-induced mice. These reductions were accompanied by reductions in proinflammatory cytokine production and inflammatory cell infiltration. Collectively, these findings indicate that melatonin effectively inhibits MUC5AC expression. These effects may be closely associated with the inhibition of MAPK phosphorylation. Furthermore, our study suggests that melatonin could represent a potential therapeutic for chronic airway diseases, such as asthma and COPD.

Comparative antioxidant effects of lycopene, apo-10′-lycopenoic acid and apo-14′-lycopenoic acid in human macrophages exposed to H2O2 and cigarette smoke extract

Much of the beneficial effects of tomato lycopene in the prevention of chronic diseases has been attributed to its antioxidant properties, which could be mediated by its metabolites and/or oxidation products. However, the biological functions of these lycopene derivatives remain still unknown. In the present study, we evaluated and compared the antioxidant efficacy of the lycopene eccentric cleavage products apo-10′-lycopenoic acid and apo-14′-lycopenoic acid in counteracting the oxidative effects of H2O2 and cigarette smoke extract (CSE) in THP-1 macrophages. Both apo-10′-lycopenoic acid and apo-14′-lycopenoic acid were able to inhibit spontaneous and H2O2-induced ROS production in a dose-dependent manner. Such an effect was accompanied by an inhibition of MAPK phosphorylation, by NF-κB inactivation, and by inhibition of hsp-70 and hsp-90 expressions. Both apo-lycopenoic acids also decreased CSE-induced ROS production, 8-OHdG formation and reduced the increase in NOX-4 and COX-2 expressions caused by CSE. However, in both the models of oxidative stress, apo-14′-lycopenoic acid was much more potent as an antioxidant than apo-10′-lycopenoic acid, showing antioxidant properties similar to lycopene. These data strongly suggest that apo-lycopenoic acids, and particularly apo-14′-lycopenoic acid, may mediate some of the antioxidant functions of lycopene in cells.

Molecular Basis of the Anti-Inflammatory Property Exhibited by Cyclo-Pentano Phenanthrenol Isolated from Lippia nodiflora

The objective of this study was to assess the anti-inflammatory potential of the active molecule isolated from Lippia nodiflora and to understand its molecular dynamics in Vitro inflammation models. Human Peripheral Blood Mononuclear Cells were used as models to study mitogen induced lymphocyte proliferation, cytokine mRNA expression (TNF-α, IL-1β and IL-6) and intracellular protein levels of pro-inflammatory mediators (MAPK and NF-κB). The NO release levels, on treatment with the extract and molecule, were correlated with the underlying iNOS mRNA expression in the murine macrophage cell line RAW 264.7. RT-PCR for COX-2, MMP2 and MMP9 were also performed in the cell line. The rat basophilic leukemia cell line RBL-2H3 was used as an in Vitro model for PLA2 activity. Then, 20 μg/ml of Lippia nodiflora crude methanol extract and 10 μg/ml of the purified CPP were used for subsequent studies based on the IC50 values obtained in the proliferation assay. Results demonstrate that the isolated Cyclo-pentano phenanthrenol inhibits TNF-α, IL-1β and IL-6 expression, NO release via iNOS suppression, prostaglandin biosynthesis via PLA2 and COX-2 inhibition and the activation of intracellular targets, MAPK and NF-κB. We conclude, cyclo-pentano phenanthrenol exerts its anti-inflammatory effect via inhibition of MAPK phosphorylation and NF-κB translocation.

Mechanism of CAG Regimen Eliminating Human T Cell Acute Lymphoblastic Leukemia Cell Line, A3

Objective To explore the mechanism of CAG regimen eliminating human T cell acute lymphoblastic leukemia cell line, A3 and evaluate the role played by G-CSF/G-CSFR system in this process.MethodsThe expression of G-CSFR on A3 cells was detected by flow cytometric analysis.Cell cycle parameters of A3 cells treated with different concentration of G-CSF(5ng/ml A10ng/ml A15ng/ml A20ng/ml G0ng/ml as control) were examined by propidium iodide staining.The inhibition and apoptosis rates of A3 cells caused by treatment with various combination of G-CSF, cytarabine (Ara-C), and aclarubicin (ACR) after incubation for 48h were analyzed by Cell Counting Kit (CCK-8) and AnnexinV staining, respectively.After incubation for 48 hours with G-CSF and PD98059(the specific inhibitor of MEK in Ras-MAPK signaling pathway), cell cycle and cell dynamic change were examined.ResultsThe expression frenquency of G-CSFR on A3 cells was 94.2% which was comparable to that of KG-1 cells.The proportion of A3 cells in S-phase was elevated concomitantly with the increasing G-CSF concentrations within 0–20ng/ml, highest at 15ng/ml of G-CSF.After incubation with Ara-C and G-CSF for 48 hours, the proliferation of A3 cells was inhibited more significantly than incubation with incubation with Ara-C alone (P<0.05, Ara-C 10−5M and 10−6M) by CCK-8 assay.Incubated with Ara-C, ACR, and G-CSF for 48 hours, the apoptosis of A3 cells was increased than that treated with Ara-C and ACR.With the concentration of PD98059 increased gradually, the proportion of A3 cells in S-phase and OD values of A3 cells decreased, which was less than that of control group (p<0.05).ConclusionG-CSFR was expressed on A3 cells.G-CSF/G-CSFR system had a synergetic effect on eliminating A3 cells when administrated simultaneously with chemical agents by driving G0-phase cells into S-phase. Apoptosis was one of the mechanisms of CAG regimen eliminating A3 cells.The interaction between G-CSF and G-CSFR activates a series of signaling pathways which includes Ras-MAPK. The inhibition of MAPK phosphorylation by PD98059 contributed partially to the effect of G-CSF on A3 cells.

Bikunin suppresses expression of pro-inflammatory cytokines induced by lipopolysaccharide in neutrophils

Activated neutrophils contribute to the development of preterm delivery. Because of its ability to suppress inflammation, bikunin, a Kunitz-type protease inhibitor, is currently in clinical trials. To investigate the molecular mechanism of this inhibition, we analyzed the effect of bikunin on pro-inflammatory cytokine production and nuclear factor-kappaB (NF-kappaB) activation in mouse neutrophils stimulated by lipopolysaccharide (LPS), an inflammatory inducer. Here, we show that bikunin: (i) blocks LPS-induced secretion of pro-inflammatory cytokines, including TNF-alpha and IL-1beta, in a dose-dependent manner; (ii) has an inhibitory effect on cytokine production at a concentration of 0.2 microM, reaching 65% inhibition at the highest doses of bikunin tested (5 microM); (iii) has the suppressive capacity of ERK1/2 and p38 signaling pathways; and (iv) inhibited sequentially the LPS-induced phosphorylation of IkappaB-alpha, degradation of IkappaB-alpha, and nuclear translocation of NF-kappaB. When the MAPK data are analyzed, a significant decrease in phosphorylation is not seen at 0.2 microM bikunin but is at 1.0 microM dosing. Bikunin can inhibit LPS-induced neutrophil activation and cytokine release, although it is unlikely that it works primarily through the inhibition of MAPK phosphorylation. These data suggest that such effects are important in vivo and play a major contributory role in abrogation of neutrophil-mediated inflammatory responses, such as preterm delivery.

Autocrine/Paracrine Regulation of Breast Cancer Cell Proliferation by Growth Hormone Releasing Hormone via Ras, Raf, and Mitogen-Activated Protein Kinase

Although GHRH has previously been shown to regulate proliferation of breast cancer cells and prevent apoptosis, the intracellular pathways mediating this effect have not been clarified. Exogenous GHRH stimulated a dose-dependent proliferative response within 24 h in MDA-231, as well as in T47D cells and in MCF-7 cells transfected with the GHRH receptor. The proliferation of MDA-MB-231 (MDA-231) cells was associated with an increase in tritiated thymidine uptake. In addition, phosphorylation of MAPK was rapidly stimulated by GHRH. The phosphorylation of MAPK by GHRH was prevented by transfection of the cells with dominant-negative Ras or Raf or by pretreatment of cells with Raf kinase 1 inhibitor. The inhibition of Ras and Raf, as well as the inhibition of MAPK phosphorylation by PD98059, also prevented GHRH-induced cell proliferation. Finally, pretreatment of cells with the somatostatin analog, BIM23014, also prevented GHRH-induced MAPK phosphorylation and cell proliferation. These results indicate that GHRH stimulates dose-dependent cell proliferation of MDA-231 breast cancer cells through a pathway that requires Ras, Raf, and MAPK phosphorylation. The results also provide support for a possible autocrine/paracrine antagonism between GHRH and somatostatin in the regulation of MDA-231 cell population maintenance. Taken together, the studies provide further insight into the possible role of GHRH as a growth factor in breast cancer.

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Maintenance of Vascular Integrity in the Embryo Requires Signaling through the Fibroblast Growth Factor Receptor

Basic fibroblast growth factor (FGF)-2 is important for vessel formation and/or maintenance of vascular integrity in the embryo. FGF signaling may be mediated through transmembrane tyrosine kinase receptors or directly through intracellular pathways that do not involve receptor activation. To determine the role of receptor-mediated signaling in endothelial cells, an adenovirus encoding truncated FGF receptor (FGFR)-1, under the control of the cytomegalovirus promoter, was expressed in endothelial cells. FGF signaling was impaired, as indicated by inhibition of MAPK phosphorylation. Functional consequences included inhibition of endothelial cell migration and induction of apoptosis. To address the role of endothelial FGFR signaling in vascular development, recombinant adenovirus encoding a dominant-negative FGFR was injected into the sinus venosus of embryonic day 9.0 cultured mouse embryos. Previous studies demonstrated that transgenes delivered via adenovirus, under the control of the cytomegalovirus promoter, are expressed selectively in the developing vasculature. Embryos expressing a control adenovirus developed normally, whereas those expressing the FGFR-1 mutant exhibited abnormal embryonic and extra-embryonic vascular development. These data demonstrate that FGF, by signaling through the FGFR, plays a pivotal role in the development and maintenance of a mature vascular network in the embryo.