Suppressing Mitogen-activated Protein Kinase Signaling Research Articles

Licochalcone A induces cell cycle arrest and apoptosis via suppressing MAPK signaling pathway and the expression of FBXO5 in lung squamous cell cancer.

Lung squamous cell carcinoma (LSCC) is a highly heterogeneous malignancy with high mortality and few therapeutic options. Licochalcone A (LCA, PubChem ID: 5318998) is a chalcone extracted from licorice and possesses anticancer and anti‑inflammatory activities. The present study aimed to elucidate the anticancer effect of LCA on LSCC and explore the conceivable molecular mechanism. MTT assay revealed that LCA significantly inhibited the proliferation of LSCC cells with less cytotoxicity towards human bronchial epithelial cells. 5‑ethynyl‑2'‑deoxyuridine (EdU) assay demonstrated that LCA could reduce the proliferation rate of LSCC cells. The flow cytometric assays indicated that LCA increased the cell number of the G1 phase and induced the apoptosis of LSCC cells. LCA downregulated the protein expression of cyclin D1, cyclin E, CDK2 and CDK4. Meanwhile, LCA increased the expression level of Bax, cleaved poly(ADP‑ribose)polymerase‑1 (PARP1) and caspase 3, as well as downregulated the level of Bcl‑2. Proteomics assay demonstrated that LCA exerted its antitumor effects via inhibiting mitogen‑activated protein kinase (MAPK) signaling pathways and the expression of F‑box protein 5 (FBXO5). Western blot analysis showed that LCA decreased the expression of p‑ERK1/2, p‑p38MAPK and FBXO5. In the xenograft tumors of LSCC, LCA significantly inhibited the volumes and weight of tumors in nude mice with little toxicity in vital organs. Therefore, the present study demonstrated that LCA effectively inhibited cell proliferation and induced apoptosis invitro, and suppressed xenograft tumor growth invivo. LCA may serve as a future therapeutic candidate of LSCC.

Synergistic antitumor activity of regorafenib and rosuvastatin in colorectal cancer.

Introduction: Colorectal cancer is one of the most prevalent life-threatening malignant tumors with high incidence and mortality. However, the efficacy of current therapeutic regimens is very limited. Regorafenib has been approved for second- or third-line treatment of patients who are refractory to standard chemotherapy diagnosed with metastatic colorectal cancer, but its clinical efficacy needs to be further improved. Accumulating evidence demonstrates that statins also possess potent anticancer activities. However, whether regorafenib and statins pose synergistic anticancer effects in colorectal cancer is still unclear. Methods: Sulforhodamine B (SRB) assays were applied to evaluate the anti-proliferative activity of regorafenib or/and rosuvastatin in vitro, and immunoblotting analysis were applied to detect the effects of regorafenib/rosuvastatin combined treatment on mitogen-activated protein kinase (MAPK) signaling and apoptosis-related proteins. MC38 tumors were applied to investigate the synergistic anticancer effects of regorafenib in combination with rosuvastatin in vivo. Results: We found that regorafenib in combination with rosuvastatin exerted significant synergistic inhibition against colorectal cancer growth in vitro and in vivo. Mechanistically, regorafenib and rosuvastatin combination synergistically suppressed MAPK signaling, a crucial signaling pathway promoting cell survival, as indicated by the reduction of phosphorylated MEK/ERK. In addition, regorafenib in combination with rosuvastatin synergistically induced the apoptosis of colorectal cancer in vitro and in vivo. Discussion: Our study demonstrated the synergistic anti-proliferative and pro-apoptotic effects of regorafenib/rosuvastatin combined treatment in colorectal cancer in vitro/vivo and might potentially be evaluated as a novel combination regimen for clinical treatment of colorectal cancer.

Isoflavones daidzin and daidzein inhibit lipopolysaccharide-induced inflammation in RAW264.7 macrophages

BackgroundInflammation contributes to various diseases and soybeans and legumes are shown to reduce inflammation. However, the bioactive ingredients involved and mechanisms are not completely known. We hypothesized that soy isoflavones daidzin and daidzein exhibit anti-inflammatory effect in lipopolysaccharides (LPS)-stimulated RAW264.7 macrophage cell model and that activation mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways may mediate the effect.MethodsCell viability and nitric oxide (NO) level were determined by 3-(4,5)-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and Griess reagent respectively. ELISA kits and Western blotting respectively assessed the generations of pro-inflammatory cytokines and protein expressions of signaling molecules. p65 nuclear translocation was determined by immunofluorescence assay.ResultsThe in vitro results showed that both isoflavones did not affect cell viability at the concentrations being tested and significantly reduced levels of NO, pro-inflammatory cytokines such as interleukin (IL)-6 and tumor necrosis factor-α (TNF-α), and inflammatory indicators such as cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in RAW264.7 cells. Daidzin and daidzein partially suppressed MAPK signaling pathways, reducing the phosphorylation of p38 and ERK; whilst phosphorylation of JNK was mildly but not significantly decreased. For the involvement of NF-κB signaling pathways, daidzin only reduced the phosphorylation of p65 whereas daidzein effectively inhibited the phosphorylation of IKKα/β, IκBα and p65. Daidzin and daidzein inhibited p65 nuclear translocation, comparable with dexamethasone (positive control).ConclusionThis study supports the anti-inflammatory effects of isoflavones daidzin and daidzein, which were at least partially mediated through inactivation of MAPK and/or NF-κB signaling pathways in macrophages.

Dihydropyrazine suppresses TLR4-dependent inflammatory responses by blocking MAPK signaling in human hepatoma HepG2 cells.

Dihydropyrazines (DHPs), including 3-hydro-2,2,5,6-tetramethylpyrazine (DHP-3), are glycation products generated through non-enzymatic reactions in vivo and in food. They are recognized as compounds that are toxic to organisms as they produce radicals. However, our previous study indicated that DHP-3 suppressed Toll-like receptor 4 (TLR4) expression and decreased the phosphorylation of nuclear factor-κB (NF-κB) in lipopolysaccharide (LPS)-treated HepG2 cells. TLR4 signaling is involved in the onset of various inflammatory diseases, and NF-κB and mitogen-activated protein kinase (MAPK) play important roles in TLR4 signaling. Thus, we aimed to elucidate the effects of DHP-3 on MAPK signaling and in turn on the activated TLR4 signaling pathway. In LPS-stimulated HepG2 cells, DHP-3 reduced the phosphorylation of MAPK, extracellular signal-regulated kinase, c-Jun NH2-terminal kinase, and p38. The expression of c-jun, a subunit of activator protein-1, was decreased by DHP-3 treatment. Furthermore, DHP-3-induced suppression of MAPK signaling resulted in a decrease in various inflammatory regulators, such as interleukin-6, CC-chemokine ligand 2, and cyclooxygenase-2. These results suggest that DHP-3 exerts an inhibitory effect on TLR4-dependent inflammatory response by suppressing MAPK signaling.

Dapansutrile ameliorated chondrocyte inflammation and osteoarthritis through suppression of MAPK signaling pathway.

Osteoarthritis (OA) is one of the most common joint diseases in the elderly population. Proinflammatory cytokines, such as Interleukin-1β (IL-1β), play an important role in the development and progression of OA. Dapansutrile is a specific inhibitor of the NOD-like receptor protein 3 (NLRP3) inflammasome and exhibits anti-inflammatory properties. In this study, we investigated the protective effect and the underlying mechanism of dapansutrile on cartilage degeneration in vitro and in vivo. In the present study, chondrocytes were isolated from rats and then were treated with dapansutrile. After that, the expression of (Cox-2, inducible nitric oxide synthase (iNOS), Mmp-3, Mmp-9, Mmp-13 and IL-10) were evaluated at RNA level, then the expression of (COX-2, MMP-3, MMP-9, MMP-13, SOX-9 and COL2) were evaluated at protein level. Subsequently, the activation of the mitogen-activated protein kinase (MAPK) pathway was tested using western blotting (WB). Additionally, the rat OA model was developed to evaluate the protective effects of dapansutrile in vivo. The results showed that dapansutrile had no obvious cytotoxicity on rat chondrocytes at 24h (0, 1, 2, 5 and 10μM). Dapansutrile significantly decreased IL-1β-induced upregulation of COX2, iNOS, matrix metalloproteinase 3 (MMP3), 9 (MMP9) and 13 (MMP13), and reversed IL-1β-induced the downregulation of IL-10, SOX9 and COL2. Dapansutrile also inhibited IL-1β-induced upregulation of the MAPK signaling pathway by downregulating the expression levels of phospho-ERK, and phospho-P38 in a concentration dependent manner. In addition, dapansutrile exhibited protective effects in rat OA model with lower Mankin's score and Osteoarthritis Research Society International (OARSI) score. Our study suggested that dapansutrile effectively inhibited chondrocyte inflammation by suppressing MAPK signaling pathway in vitro, and ameliorated cartilage degeneration in vivo, indicating an anti-inflammatory effect in OA treatment.

DLC1 inhibits lung adenocarcinoma cell proliferation, migration and invasion via regulating MAPK signaling pathway

Lung adenocarcinoma (LUAD), one of the most common cancers, is a major threat to people’s health due to its high mortality, and the survival of most patients suffering LUAD remains poor. This study aimed to explore the mechanism of Deleted in Liver Cancer 1 (DLC1) as a tumor suppressor underlying the occurrence and progression of LUAD. As revealed by bioinformatics analysis and qRT-PCR, DLC1 was significantly down-regulated in LUAD tumor tissue and cells. A series of cellular experiments including CCK-8, wound healing and Transwell assays were performed to detect the effect of DLC1 on the biological function of LUAD cells. It was found that overexpressing DLC1 significantly inhibited LUAD cell proliferative, migratory and invasive abilities, while knockdown of DLC1 promoted these abilities. Gene Set Enrichment Analysis (GSEA) and dual-luciferase assay were used to explore the downstream signaling pathway of DLC1, finding that DLC1 could remarkably inhibit the activity of mitogen-activated protein kinase (MAPK) signaling pathway. Western blot implemented for MAPK signaling pathway-related proteins further identified that DLC1 restrained the activation of MAPK/ERK signaling pathway. Furthermore, rescue experiments suggested that DLC1 inhibited LUAD cell proliferation and invasion by suppressing the MAPK/ERK signaling pathway. Overall, our study discussed the DLC1-dependent mechanism involved in LUAD. We found that the up-regulation of DLC1 may inhibit the malignant progression of LUAD by suppressing MAPK signaling pathway, which supports the view that DLC1 may serve as a molecular target for the targeted therapy of LUAD patients.

Qingxue jiedu formulation ameliorated DNFB-induced atopic dermatitis by inhibiting STAT3/MAPK/NF-κB signaling pathways

Ethnopharmacological relevanceQingxue jiedu Formulation (QF) is composed of two classic prescriptions which have been clinically used for more than 5 centuries and appropriately modified through basic theory of traditional Chinese medicine for treating various skin inflammation such as atopic dermatitis (AD), acute dermatitis and rash. Although QF possesses a prominent clinical therapeutic effect, seldom pharmacological studies on its anti-AD activity are conducted. Aim of the studyWe used AD mice model to investigate the anti-AD activities of QF, as well as its underlying molecular mechanisms which involved signal transducer and activator of transcription 3 (STAT3), nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways. Materials and methods2,4-dinitrofluorobenzene (DNFB)-induced AD mice were used to collect serum and skin tissues for consequential determination. The levels of various inflammatory factors [interleukin (IL)-12, Interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-4, IL-6 and immunoglobulin E (IgE)] were determined by enzyme-linked immunosorbent assay (ELISA). Real-time polymerase chain reaction (RT-PCR) was contributed to detect the effects of relevant inflammatory factors on mRNA. The roles of STAT3, NF-κB and MAPK signaling pathways in AD response were analyzed by Western blotting (WB), and the thickening of mice dorsal skin and inflammatory cell infiltration were observed by hematoxylin and eosin (H&E) staining. ResultsQF significantly reduced the skin thickening, inflammatory cell infiltration and other symptoms in AD mice. The levels of IL-12, TNF-α, IL-4, IL-6 and IgE were decreased, while IFN-γ was increased by QF in the ELISA analysis. QF lessened the levels of lL-6 and elevated IFN-γ on the mRNA level. In addition, WB analysis showed QF thoroughly inhibited the activation of NF-κB, STAT3 and phosphorylation of JAK1, JAK2, JAK3, while partially suppressed MAPK signaling pathways. ConclusionsQF inhibited the activations of STAT3, MAPK and NF-κB signaling pathways and possessed a significant therapeutic effect on AD. Therefore, QF deserves our continuous attention and research as a prominent medicine for AD.

Lentinan, a Shiitake Mushroom ß-Glucan, Downregulates the Enhanced PD-L1 Expression Induced by Platinum Compounds in Gastric Cancer Cells -

Background: Despite recent therapeutic improvements, the prognosis of unresectable gastric cancer remains poor. Upregulation of programmed cell death ligand 1 (PD-L1) in tumor cells is believed to be an important mechanism to escape from the host immune response. The expression of PD-L1 in tumors is regulated in a highly complex manner by various upstream signaling molecules, depending on the cell type. Given that the efficacy of chemotherapeutic agents for metastatic gastric cancer is limited due to immune escape caused by enhanced PD-L1 expression, PD-1/PD-L1 targeted immunotherapy may be a promising alterative for chemotherapy. However, immune checkpoint inhibitor monotherapy has shown clinical benefits in less than 20% of patients with gastric cancer and its underlying mechanism remains to be elucidated. On the other hand, lentinan, a glucan purified from Shiitake mushrooms, has significant immune-stimulating effects and has been reported to improve survival in patients with metastatic gastric cancer receiving chemotherapy. In the current study we investigated the mechanism by which lentinan increases the chemotherapeutic efficacy by focusing on the expression of PD-L1. Methods: To evaluate the effects of lentinan as well as antineoplastic agents, the expression of PD-L1 and associated molecules was analyzed by real-time polymerase chain reaction and western blotting using the human gastric cancer cell lines, NUGC3, MKN1, and MKN45. Results: Treatment with either cisplatin or oxaliplatin dose-dependently enhanced PD-L1 mRNA and protein expression through the mitogen-activated protein kinase (MAPK) pathway in gastric cancer cells. However, lentinan treatment inhibited the platinum drug-stimulated expression of PD-L1 in gastric cancer cells mainly by suppressing MAPK signaling without affecting the phosphatidylinositol-3 kinase/AKT pathway or transcription factors. Conclusions: Platinum-based drugs enhanced the expression of PD-L1 via the MAPK pathway in gastric cancer cells. Lentinan downregulated PD-L1 expression induced by either cisplatin or oxaliplatin, suggesting that a combination of this glucan and platinum-based chemotherapy could restore the chemosensitivity of cells.

Zerumbone ameliorates behavioral impairments and neuropathology in transgenic APP/PS1 mice by suppressing MAPK signaling

BackgroundAlzheimer’s disease (AD) is a major clinical problem, but there is a distinct lack of effective therapeutic drugs for this disease. We investigated the potential therapeutic effects of zerumbone, a subtropical ginger sesquiterpene, in transgenic APP/PS1 mice, rodent models of AD which exhibit cerebral amyloidosis and neuroinflammation.MethodsThe N9 microglial cell line and primary microglial cells were cultured to investigate the effects of zerumbone on microglia. APP/PS1 mice were treated with zerumbone, and non-cognitive and cognitive behavioral impairments were assessed and compared between the treatment and control groups. The animals were then sacrificed, and tissues were collected for further analysis. The potential therapeutic mechanism of zerumbone and the signaling pathways involved were also investigated by RT-PCR, western blot, nitric oxide detection, enzyme-linked immunosorbent assay, immunohistochemistry, immunofluorescence, and flow cytometry analysis.ResultsZerumbone suppressed the expression of pro-inflammatory cytokines and induced a switch in microglial phenotype from the classic inflammatory phenotype to the alternative anti-inflammatory phenotype by inhibiting the mitogen-activated protein kinase (MAPK)/nuclear factor-kappa B signaling pathway in vitro. After a treatment period of 20 days, zerumbone significantly ameliorated deficits in both non-cognitive and cognitive behaviors in transgenic APP/PS1 mice. Zerumbone significantly reduced β-amyloid deposition and attenuated pro-inflammatory microglial activation in the cortex and hippocampus. Interestingly, zerumbone significantly increased the proportion of anti-inflammatory microglia among all activated microglia, potentially contributing to reduced β-amyloid deposition by enhancing phagocytosis. Meanwhile, zerumbone also reduced the expression of key molecules of the MAPK pathway, such as p38 and extracellular signal-regulated kinase.ConclusionsOverall, zerumbone effectively ameliorated behavioral impairments, attenuated neuroinflammation, and reduced β-amyloid deposition in transgenic APP/PS1 mice. Zerumbone exhibited substantial anti-inflammatory activity in microglial cells and induced a phenotypic switch in microglia from the pro-inflammatory phenotype to the anti-inflammatory phenotype by inhibiting the MAPK signaling pathway, which may play an important role in its neuroprotective effects. Our results suggest that zerumbone is a potential therapeutic agent for human neuroinflammatory and neurodegenerative diseases, in particular AD.

Asymmetric dimethylarginine targets MAPK pathway to regulate insulin resistance in liver by activating inflammation factors.

Insulin resistance is associated with impaired glucose uptake and altered protein kinase B (Akt) signaling. Previous studies have suggested asymmetric dimethylarginine (ADMA) and inflammation are two distinguish factors that correlate with insulin resistance (IR). How ADMA and inflammation factors interact and synchronize in the regulation of IR in liver remain to be elucidated. In this study, we systematically investigated whether ADMA is involved in IR using primary hepatocytes, if yes, by via which molecular mechanism. Our results demonstrated that ADMA inhibits insulin sensitivity in a concentration-dependent manner by activating inflammation factors tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-6 in primary hepatocytes. Further analysis revealed that mitogen-activated protein kinase (MAPK) signaling pathway act downstream of ADMA and inflammation factors, and inhibition of MAPK pathway rescued the IR. Furthermore, metformin effects has been found which could reverse ADMA-induced IR by suppressing MAPK signaling pathway. To our knowledge, we, for the first time, unveiled the complicated regulatory network and interactions among ADMA, inflammation, and MAPK signaling pathway, which advanced current research on the development and regulation of IR in liver. This study also certainly provided novel insights on comprehensive diagonistics roles of ADMA as a potential biomarker.

Abstract A46: KLF4 overcomes tamoxifen resistance by suppressing MAPK signaling pathway in breast cancer

Abstract Krüppel-like factor 4 (KLF4) has critical roles in breast cancer development and progression and several solid tumors. Tamoxifen (TAM) resistance represents a daunting challenge to the successful treatment of breast cancer. KLF4 expression, function, and regulation in the efficacy of TAM therapy in breast cancer have yet to be demonstrated. Here, we investigated the clinical significance and biologic effects of KLF4 in breast cancer. Firstly, higher expression of KLF4 was correlated with increased TAM sensitivity in breast cells, and analysis of GEO datasets indicated that KLF4 expression was positively correlated with ERa and enhanced expression of KLF4 sensitized breast cancer patients to endocrine therapy. Knockdown of KLF4 in MCF-7 and BCAP37 cells led to increased TAM resistance, while ectopic KLF4 expression promoted the responsiveness of MCF-7/TAM and T47D cells to TAM. Secondly, ectopic KLF4 overexpression suppressed MCF-7/TAM cell growth, invasion, and migration ability. Besides, KLF4 expression was downregulated in breast cancer tumor tissues and high expression of KLF4 linked to favorable outcome. Mechanistically, KLF4 may enhance the responsiveness of breast cancer cells to TAM through suppressing mitogen-activated protein kinase (MAPK) signaling pathway. We found that ERK and P38 were relatively activated in MCF-7/TAM compared with MCF-7, and treatment with MAPK-specific inhibitors can significantly suppress cell viability. Knockdown of KLF4 activated ERK and P38 and drove MCF-7 cells to become resistant to TAM. Conversely, overexpression of KLF4 in MCF-7/TAM cells suppressed ERK and P38 signaling and resulted in enhanced sensitivity to TAM. Therefore, our findings suggest that KLF4 contributes to TAM efficiency in breast cancer via phosphorylation modification of ERK and P38 signaling. Collectively, this study highlighted the significance of KLF4/MAPK signal interaction in regulating TAM resistance of breast cancer, and suggested that targeting the KLF4/MAPK signaling may be a potential therapeutic strategy for breast cancer treatment, especially for TAM-resistant patients. Note: This abstract was not presented at the conference. Citation Format: Yunlu Jia, Wang Linbo. KLF4 overcomes tamoxifen resistance by suppressing MAPK signaling pathway in breast cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Breast Cancer Research; 2017 Oct 7-10; Hollywood, CA. Philadelphia (PA): AACR; Mol Cancer Res 2018;16(8_Suppl):Abstract nr A46.

KLF4 overcomes tamoxifen resistance by suppressing MAPK signaling pathway and predicts good prognosis in breast cancer

Tamoxifen resistance represents a daunting challenge to the successful treatment for breast cancer. Krüppel-like factor 4 has critical roles in the development and progression of breast cancer, but its expression, function and regulation in the efficacy of TAM therapy in breast cancer have yet to be investigated. Here, we examined the clinical significance and biologic effects of KLF4 in breast cancer. Firstly, higher expression of KLF4 correlated with increased TAM sensitivity in breast cancer cells, and analysis of GEO datasets indicated that KLF4 expression was positively correlated with ERα and enhanced expression of KLF4 sensitized breast cancer patients to endocrine therapy. Knockdown of KLF4 in MCF-7 and BCAP37 cells led to increased TAM resistance, while ectopic KLF4 expression promoted the responsiveness to TAM in T47D and TAM-resistant MCF-7/TAM cells. Secondly, ectopic KLF4 overexpression suppressed MCF-7/TAM cell growth, invasion and migration. Moreover, KLF4 expression was down-regulated in breast cancer tumor tissues and high expression of KLF4 was associated with favorable outcomes. Mechanistically, KLF4 may enhance the responsiveness of breast cancer cells to TAM through suppressing mitogen-activated protein kinase (MAPK) signaling pathway. We found that ERK and p38 were more activated in MCF-7/TAM compared with MCF-7, and treatment with MAPK-specific inhibitors significantly suppressed cell viability. Knockdown of KLF4 activated ERK and p38 and drove MCF-7 cells to become resistant to TAM. Conversely, overexpression of KLF4 in MCF-7/TAM cells suppressed ERK and p38 signaling and resulted in increased sensitivity to TAM. Therefore, our findings suggested that KLF4 contributed to TAM sensitivity in breast cancer via phosphorylation modification of ERK and p38 signaling. Collectively, this study highlighted the significance of KLF4/MAPK signal interaction in regulating TAM resistance of breast cancer, and suggested that targeting KLF4/MAPK signaling may be a potential therapeutic strategy for breast cancer treatment, especially for the TAM-resistant patients.

Tonggyu-tang, a traditional Korean medicine, suppresses pro-inflammatory cytokine production through inhibition of MAPK and NF-\u03baB activation in human mast cells and keratinocytes

BackgroundAllergic diseases including allergic rhinitis, asthma, and atopic dermatitis are increasing worldwide. Common medications used to treat these inflammatory disorders are anti-histamines and corticosteroids, but they have their own limitations such as short duration and severe side effects. Thus, interest in complementary and alternative medicine is continually growing. Here, we investigate the anti-inflammatory mechanisms of Tonggyu-tang (TGT), a traditional Korean medicine that has been used to treat patients with allergic nasal disorders.MethodsWe measured mRNA expressions and production of pro-inflammatory cytokines such as interleukin (IL)-4, IL-6, IL-8 and tumor necrosis factor alpha (TNF-α) by RT-PCR and ELISA assays in HMC-1 (human mast cell line-1) and HaCaT cells, immortalized human keratinocytes. Moreover, we evaluated the effect of TGT on two major inflammation-related pathways, mitogen activated protein kinase (MAPK) and NF-κB signaling pathway in these two cells.ResultsOur results revealed that that TGT significantly reduced the expression and production of inflammatory cytokines such as IL-4, IL-6, IL-8, and TNF-α in the agonist-treated HMC-1 and HaCaT cells. We also found that TGT suppressed MAPK signaling pathway including extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (p38), and c-Jun N-terminal kinase (JNK) as well as NF-κB pathway, which are known to regulate inflammatory cytokine expression.ConclusionTaken together, our results demonstrate that TGT inhibits expression of pro-inflammatory cytokines by suppressing MAPK and NF-kB pathway in both mast cells and keratinocytes, suggesting the potential use of TGT in treating allergic inflammatory diseases.

Concurrent MEK targeted therapy prevents MAPK pathway reactivation during BRAFV600E targeted inhibition in a novel syngeneic murine glioma model.

Inhibitors of BRAFV600E kinase are currently under investigations in preclinical and clinical studies involving BRAFV600E glioma. Studies demonstrated clinical response to such individualized therapy in the majority of patients whereas in some patients tumors continue to grow despite treatment. To study resistance mechanisms, which include feedback activation of mitogen-activated protein kinase (MAPK) signaling in melanoma, we developed a luciferase-modified cell line (2341luc) from a BrafV600E mutant and Cdkn2a- deficient murine high-grade glioma, and analyzed its molecular responses to BRAFV600E- and MAPK kinase (MEK)-targeted inhibition. Immunocompetent, syngeneic FVB/N mice with intracranial grafts of 2341luc were tested for effects of BRAFV600E and MEK inhibitor treatments, with bioluminescence imaging up to 14-days after start of treatment and survival analysis as primary indicators of inhibitor activity. Intracranial injected tumor cells consistently generated high-grade glioma-like tumors in syngeneic mice. Intraperitoneal daily delivery of BRAFV600E inhibitor dabrafenib only transiently suppressed MAPK signaling, and rather increased Akt signaling and failed to extend survival for mice with intracranial 2341luc tumor. MEK inhibitor trametinib delivered by oral gavage daily suppressed MAPK pathway more effectively and had a more durable anti-growth effect than dabrafenib as well as a significant survival benefit. Compared with either agent alone, combined BRAFV600E and MEK inhibitor treatment was more effective in reducing tumor growth and extending animal subject survival, as corresponding to sustained MAPK pathway inhibition. Results derived from the 2341luc engraftment model application have clinical implications for the management of BRAFV600E glioma.

Astilbin alleviates LPS-induced ARDS by suppressing MAPK signaling pathway and protecting pulmonary endothelial glycocalyx

Acute respiratory distress syndrome (ARDS) is a devastating disorder that is characterized by increased vascular endothelial permeability and inflammation. Unfortunately, no effective treatment beyond supportive care is available for ARDS. Astilbin, a flavonoid compound isolated from Rhizoma Smilacis Glabrae, has been used for anti-hepatic, anti-arthritic, and anti-renal injury treatments. This study examined the effects of Astilbin on pulmonary inflammatory activation and endothelial cell barrier dysfunction caused by Gram-negative bacterial endotoxin lipopolysaccharide (LPS). Endothelial cells from human umbilical veins or male Kunming mice were pretreated with Astilbin 24h before LPS stimulation. Results showed that Astilbin significantly attenuated the pulmonary histopathological changes and neutrophil infiltration 6h after the LPS challenge. Astilbin suppressed the activities of myeloperoxidase and malondialdehyde, as well as the expression of tumor necrosis factor-α and interleukin-6 in vivo and in vitro. As indices of pulmonary edema, lung wet-to-dry weight ratios, were markedly decreased by Astilbin pretreatment. Western blot analysis also showed that Astilbin inhibited LPS-induced activation of mitogen-activated protein kinase (MAPK) pathways in lung tissues. Furthermore, Astilbin significantly inhibited the activity of heparanase and reduced the production of heparan sulfate in the blood serum as determined by ELISA. These findings indicated that Astilbin can alleviate LPS-induced ARDS, which potentially contributed to the suppression of MAPK pathway activation and the degradation of endothelial glycocalyx.

Oral administration of Lentinus edodes β-glucans ameliorates DSS-induced ulcerative colitis in mice via MAPK-Elk-1 and MAPK-PPARγ pathways.

To evaluate the anti-inflammatory effect of β-glucans from Lentinus edodes, and its molecular mechanism, the dextran sulfate sodium salt (DSS) induced colitis model of mice and the LPS-stimulated RAW264.7 cell inflammation model were used in this study. 40 ICR male mice were randomly divided into 4 groups: Control, DSS (DSS treated only), DSS + low-βGs (500 mg kg-1 d-1) and DSS + high-βGs (1000 mg kg-1 d-1). The body weight of the mice with Lentinus edodes β-glucan supplementation increased significantly compared to the DSS group and the disease activity index (DAI) was improved in both βG-treated groups. Compared with the DSS group, histopathological analysis showed that the infiltration of inflammatory cells of both βG-treated groups decreased significantly in colonic tissues. Furthermore, oral administration of β-glucans decreases the concentration of malondialdehyde (MDA) and myeloperoxidase (MPO) and inhibits the expression of iNOS and several inflammatory factors: TNF-α, IL-1β and IL-6 as well as nitric oxide (NO) of the colonic tissues. The mitogen-activated protein kinase (MAPK) pathway is closely related to the expression of pro-inflammatory factors. In the DSS-induced colitis model and the LPS-stimulated RAW264.7 cell model, βGs inhibited the expression of pro-inflammatory factors and blocked the phosphorylation of JNK/ERK1/2 and p38; βGs also suppress the phosphorylation of Elk-1 at Ser84 and the phosphorylation of PPARγ at Ser112. Altogether, these results suggest that Lentinus edodes βGs could inhibit the DSS-induced ulcerative colitis and decrease inflammatory factor expressions. The molecular mechanism may be involved in suppressing MAPK signaling and inactivation of Elk-1 and activation of PPARγ.

AP-1-Targeted Inhibition of Macrophage Function and Lipopolysaccharide/D-Galactosamine-Induced Hepatitis by Phyllanthus acidus Methanolic Extract.

Traditionally, Phyllanthus acidus (Phyllanthaceae) has been used for the treatment of rheumatism, bronchitis, asthma, respiratory disorders, and hepatitis. Recently, we showed that a methanol extract of Phyllanthaceae (Pa-ME) has a potent anti-inflammatory activity in RAW264.7 cells and strongly ameliorates HCl / EtOH -induced gastric ulcers in mice by targeting the Src/Syk of NF-κB. In the present study, we explored the molecular mechanism of Pa-ME on the AP-1 activation pathway and evaluated its potential hepatoprotective effects. To do this, we employed lipopolysaccharide (LPS)-stimulated RAW264.7 cells and U937 cells and an LPS/D-galactosamine (D- GaIN )-induced acute hepatitis mouse model. We utilized a multitude of assays, including immunoblotting analysis, reporter gene assays, and mRNA expression analysis, to determine the effect of Pa-ME on the AP-1 pathway. Pa-ME strikingly suppressed the production of LPS-induced pro-inflammatory cytokines including interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α). Furthermore, Pa-ME also strongly inhibited activator protein-1 (AP-1) activation and mitogen-activated protein kinase (MAPK) phosphorylation in LPS-stimulated RAW264.7 macrophages cells and the U937 monocyte like human cell line. Moreover, pre-treatment with Pa-ME exhibited strong hepatoprotective and curative effects in an LPS/D-Gal-induced mouse hepatitis model as evidenced by a decrease in elevated serum AST and ALT levels and the amelioration of histological damage. Taken together, our data suggest that Pa-ME might play a crucial ethnopharmacological role as a hepatoprotective herbal remedy by suppressing MAPK signaling and the activity of the downstream transcription factor AP-1.

Clopidogrel Effectively Suppresses Endothelial Microparticle Generation Induced by Indoxyl Sulfate via Inhibition of the p38 Mitogen-Activated Protein Kinase Pathway

Background/Aims: Endothelial microparticles (EMPs) are closely associated with vascular dysfunction. We investigated the effects of several drugs on EMP generation in human umbilical vein endothelial cells (HUVECs), and the involvement of the mitogen-activated protein kinase (MAPK) in EMP generation. Methods: CD31+CD42-EMP counts were measured by flow cytometry in supernatants of HUVECs incubated with indoxyl sulfate. The EMP responses to losartan, lovastatin, clopidogrel, and mesoglycan were examined. We then measured the effects of MAPK inhibitors on EMPs. Results: (1) Indoxyl sulfate induced EMP release in HUVECs in a dose-dependent fashion; (2) all drugs (10–50 µM) inhibited EMP generation induced by indoxyl sulfate, with clopidogrel being the most effective; (3) the p38 MAPK inhibitor suppressed EMP generation induced by indoxyl sulfate, and (4) clopidogrel significantly suppressed MAPK signaling activated by indoxyl sulfate, with the most potency on p38. Conclusion: The p38 signaling involves EMP generation induced by indoxyl sulfate and is effectively suppressed by clopidogrel.