To investigate whether the protection of ischemic preconditioning (IPC) against myocardial ischemia/reperfusion (I/R) injury is mediated by toll-like receptor 4 (TLR4)/NF-κB pathway, and whether these effects are related to the release of calcitonin gene-related peptide (CGRP).
Sprague-Dawley rats were subjected to 60 min of ligation of the left anterior descending coronary artery followed by 3 h of reperfusion to induce I/R injury. IPC was performed by 4 cycles of 3-min left coronary artery occlusion followed by 5-min reperfusion before the I/R. The expression of TLR4 mRNA was determined by RT-PCR. TLR4 and NF-κB protein expression were analyzed by immunohistochemistry. Myocardial infarct size, CGRP concentration in plasma and activity of creatine kinase in serum were also measured.
IPC significantly reduced the infarct size and creatine kinase activity concomitantly with the increase in plasma CGRP concentration. The expressions of TLR4 protein and mRNA and NF-κB protein were increased by myocardial I/R injury, and dramatically inhibited by IPC.
IPC protects against myocardial I/R injury by inhibition of TLR4/NF-κB pathway. These effects are related to the increased the release of CGRP.Read more
Persistently elevated level of TNF-alpha has been implicated in several inflammatory disorders, however, its autocrine production through TNF-alpha receptors signaling is poorly understood. Here we report that simultaneous silencing of TNF-receptors, R1 and R2 by DNAzyme or siRNA suppressed TNF-alpha expression more efficiently than silencing them individually in lipopolysaccharides (LPS) stimulated THP-1 macrophages. Co-silencing of TNF-receptors also inhibited TNF-alpha induced NF-kappaB activation to a higher extent. It was further observed that NF-kappaB inhibitor but not c-Jun N-terminal kinase inhibitor (SP600125) suppressed TNF-alpha expression. All these results suggest that TNF-alpha expression is regulated by synergistic signaling of TNF receptors through downstream NF-kappaB activation.Read more
Airway mucus secretion is an essential innate immune response for host protection. However, overproduction and hypersecretion of mucus, mainly composed of MUC5AC, are significant risk factors in asthma and chronic obstructive pulmonary disease (COPD) patients. Previously, we reported that verproside, a catalpol derivative iridoid glycoside isolated from Pseudolysimachion rotundum var. subintegrum, is a potent anti-asthmatic candidate drug in vivo. However, the molecular mechanisms underlying the pharmacological actions of verproside remain unknown. Here, we found that verproside significantly reduces the expression levels of tumor necrosis factor alpha (TNF-α)-induced MUC5AC mRNA and protein by inhibiting both nuclear factor kappa B (NF-κB) transcriptional activity and the phosphorylation of its upstream effectors such as IκB kinase (IKK)β, IκBα, and TGF-β-activated kinase 1 (TAK1) in NCI-H292 cells. Moreover, verproside attenuated TNF-α-induced MUC5AC transcription more effectively when combined with an IKK (BAY11-7082) or a TAK1 (5z-7-oxozeaenol) inhibitor than when administered alone. Importantly, we demonstrated that verproside negatively modulates the formation of the TNF-α-receptor (TNFR) 1 signaling complex [TNF-RSC; TNFR1-recruited TNFR1-associated death domain protein (TRADD), TNFR-associated factor 2 (TRAF2), receptor-interacting protein kinase 1 (RIP1), and TAK1], the most upstream signaling factor of NF-κB signaling. In silico molecular docking studies show that verproside binds between TRADD and TRAF2 subunits. Altogether, these results suggest that verproside could be a good therapeutic candidate for treatment of inflammatory airway diseases such as asthma and COPD by blocking the TNF-α/NF-κB signaling pathway.Read more
Tamoxifen is widely used as an adjuvant therapy for patients with estrogen receptor (ERα)-positive tumors. However, the clinical benefit is often limited because of the emergence of drug resistance. In this study, overexpression of ribonucleotide reductase M2 (RRM2) in MCF-7 breast cancer cells resulted in a reduction in the effectiveness of tamoxifen, through downregulation of ERα66 and upregulation of the 36-kDa variant of ER (ERα36). We identified that NF-κB, HIF1α, and MAPK/JNK are the major pathways that are affected by RRM2 overexpression and result in increased NF-κB activity and increased protein levels of EGFR, HER2, IKKs, Bcl-2, RelB, and p50. RRM2-overexpressing cells also exhibited higher migratory and invasive properties. Through time-lapse microscopy and protein profiling studies of tamoxifen-treated MCF-7 and T-47D cells, we have identified that RRM2, along with other key proteins, is altered during the emergence of acquired tamoxifen resistance. Inhibition of RRM2 using siRRM2 or the ribonucleotide reductase (RR) inhibitor didox not only eradicated and effectively prevented the emergence of tamoxifen-resistant populations but also led to the reversal of many of the proteins altered during the process of acquired tamoxifen resistance. Because didox also appears to be a potent inhibitor of NF-κB activation, combining didox with tamoxifen treatment cooperatively reverses ER-α alterations and inhibits NF-κB activation. Finally, inhibition of RRM2 by didox reversed tamoxifen-resistant in vivo tumor growth and decreased in vitro migratory and invasive properties, revealing a beneficial effect of combination therapy that includes RRM2 inhibition to delay or abrogate tamoxifen resistance.Read more
p50 is a member of the NF-kappaB family known to be involved in endometriosis. To gain insight into the roles of p50 in the development of endometriosis, we cross-transplanted endometrial fragments from p50 knockout mice to wild-type mice and vice versa, and also autotransplanted the fragments within the knockout and wild-type mice, inducing endometriosis. We then evaluated the size of the endometrial implants, and immunoreactivity to phosphorylated p65 (p-p65), PKCepsilon and TRPV1 in ectopic and eutopic endometrium as well as in vagina. We found that p50 deletion significantly reduces the size of endometrial implants. The immunoreactivity to p-p65 and PKCepsilon, but not TRPV1, was reduced in endometrial implants in p50 knockout mice. Deletion of p50 significantly reduced p-p65 and PKCepsilon, but not TRPV1, expression in eutopic endometrium and vagina. It also disrupts NF-kappaB activation and PKCepsilon expression in eutopic and vagina, suggesting the role of NF-kappaB in regulating PKCepsilon, which plays an important role in nociception. These data show that p50 is involved in the development of endometriosis and may be a promising therapeutic target.Read more
Accumulating evidence indicates that cancer stem cells (CSCs) are a source of resistance to radiation therapy (RT); however, the mechanism of this resistance remains unclear. 2-Methoxyestradiol (2-ME2) is a metabolic product of estrogen in the body. Recent studies have found that 2-ME2 regulates the activation of transcription factors, including nuclear factor (NF)-κB/hypoxia-inducible factor-1 (HIF-1), thus contributing to tumor cell apoptosis and chemosensitivity. Therefore, 2-ME2 is being studied as a potential anticancer drug. The purpose of this study was to determine the effect and mechanism by which 2-ME2 inhibits nasopharyngeal carcinoma CNE-2 stem-like cell (NPCSC) proliferation and migration and reduces NPCSC radioresistance. This study has important significance for reducing the radioresistance of these cells to improve the cure rate of NPC. First, the NPCSCs were collected in a serum-free culture system and then identified by relevant experiments. The NPCSCs were treated with 2-ME2 (0-8 µM) combined with X-ray exposure and Cell Counting Kit-8 (CCK-8), Transwell assay, colony formation assay, western blot analysis, RT-PCR, flow cytometry and RNA interference technology were used to explore the effect and mechanism of 2-ME2 on NPCSCs. The results showed that the microspheres collected in the serum‑free culture system possessed CSC traits and radioresistance. 2-ME2 obviously inhibited NPCSC growth and migration and reduced NPCSC radioresistance. 2-ME2 decreased NF-κB p65 and HIF-1α protein expression, downregulated NF-κB p65 nuclear localization, and reversed epithelial-mesenchymal transition (EMT). NF-κB p65 knockdown reduced HIF-1α expression, reversed EMT, and enhanced the suppressive effect of 2-ME2 on NPCSCs. Collectively, these data indicate that 2-ME2 inhibits NPCSC proliferation and migration and reduces the radioresistance of NPCSCs via NF-κB/HIF-1 signaling pathway inactivation and EMT reversal.Read more
The aim of these in vitro studies was to examine the involvement of transcription factor NF-κB (p50/p50, p65/p65) and FSH in control of porcine ovarian granulosa cells functions and the possible role of dimers p50/p50, p65/p65 in mediating FSH actions on these cells. Monolayer of primary granulosa cells was transfected with plasmids encoding human p50 cDNA and p65 cDNA, and cultured with or without addition of FSH (0, 1, 10 or 100 ng/ml). The accumulation of proteins p50 and p65, as well as of proliferation markers (PCNA and MAPK/ERK1,2) and marker of apoptosis (Bax) in cells was detected by using SDS-PAGE-Western immunoblotting and immunocytochemistry. DNA fragmentation was evaluated by TUNEL assay. Release of hormones insulin-like growth factor I (IGF-I), progesterone (P(4)), oxytocin (OT), prostaglandins E(2) (PGE(2)) and F(2α) (PGF(2α)) was measured by using RIA. We observed, that p50/p50 promoted the accumulation of PCNA, MAPK/ERK1,2, the release of OT, PGF(2α); inhibited the occurrence of TdT-positive cells, the release of IGF-I and P(4), and did not influence the accumulation of Bax and the release of PGE(2). p65/p65 enhanced the accumulation of PCNA, MAPK/ERK1,2 and Bax, the release of IGF-I, OT, PGE(2) and PGF(2α); decreased the percentage of cell containing TdT and did not affect the release of P(4). FSH stimulated the accumulation of PCNA, MAPK/ERK1,2 and Bax, the release of IGF-I, OT, P(4), PGE(2); but reduced the proportion of TdT-positive cells and the release of PGF(2α). These observations suggest (1) the involvement of NF-κB (p50/p50) in stimulation of proliferation, inhibition of apoptosis and in either stimulation (OT, PGE(2)) or inhibition (IGF-I, P(4), but not PGF(2)) of hormones release by porcine ovarian granulosa cells; (2) the involvement of NF-κB (p65/p65) in stimulation of proliferation and mitochondrial/Bax-related apoptosis, inhibition of nuclear/TdT-related apoptosis and in stimulation of ovarian hormones (IGF-I, OT, PGE(2), PGF(2α), but not P(4)) release; (3) the role of FSH in up-regulation of both ovarian cell proliferation and mitochondrial/Bax-related apoptosis, in inhibition of nuclear/TdT-related apoptosis, in promotion of IGF-I, P(4), OT, PGE(2) and suppression of PGF(2α) release by porcine ovarian cells. The majority of results demonstrates the involvement of NF-κB (p50/p50 and p65/p65) and FSH in control of basic ovarian functions (proliferation, apoptosis, and secretory activity), but not the functional interrelationships between these regulators.Read more
Dengue virus (DENV) infection associates with renal disorders. Patients with dengue hemorrhagic fever and acute kidney injury have a high mortality rate. Increased levels of cytokines may contribute to the pathogenesis of DENV-induced kidney injury. Currently, molecular mechanisms how DENV induces kidney cell injury has not been thoroughly investigated. Excessive cytokine production may be involved in this process. Using human cytokine RT(2) Profiler PCR array, 14 genes including IP-10, RANTES, IL-8, CXCL-9 and MIP-1β were up-regulated more than 2 folds in DENV-infected HEK 293 cells compared to that of mock-infected HEK 293 cells. In the present study, RANTES was suppressed by the NF-κB inhibitor, compound A (CpdA), in DENV-infected HEK 293 cells implying the role of NF-κB in RANTES expression. Chromatin immunoprecipitation (ChIP) assay showed that NF-κB binds more efficiently to its binding sites on the RANTES promoter in NS5-transfected HEK 293 cells than in HEK 293 cells expressing the vector lacking NS5 gene. To further examine whether the NS5-activated RANTES promoter is mediated through NF-κB, the two NF-κB binding sites on the RANTES promoter were mutated and this promoter was coupled to the luciferase cDNA. The result showed that when both binding sites of NF-κB in the RANTES promoter were mutated, the ability of NS5 to induce the luciferase activity was significantly decreased. Therefore, DENV NS5 activates RANTES production by increasing NF-κB binding to its binding sites on the RANTES promoter.Read more
This study was purposed to investigate the relationship between activation of nuclear factor-κB (NF-κB) and multidrug resistance in K562/AO₂ cells and its mechanism. Human erythroleukemic cell line K562 and its adriamycin-resistant counterpart K562/AO₂ cells were used in the study. After inhibiting the activation of NF-κB with noncytotoxic concentration of antioxidant pyrrolidine dithiocarbamate (PDTC) in vitro, the multiple of drug resistance of K562/AO₂ cells was assessed by MTT assay. RT-PCR and flow cytometry method were used to detect the relative expression of mdr-1 mRNA and P-gp, respectively. The results showed that (1) multidrug resistance of K562/AO₂ cells to ADM was 59 times higher than that of K562 cells. When being pretreated with 0.2 μmol/L PDTC which is noncytotoxic to cells, the IC₅₀ of ADM in K562/AO₂ cells was sharply decreased with relative reverse efficiency of 93.03%, which was more higher than that of classic modifying agents Verapamil (Ver); (2) NF-κB activity of K562/AO₂ cells was significantly higher than that of K562 cells (p < 0.01). When being treated with PDTC, the activation of NF-κB was sharply decreased in K562/AO₂ cells; with 0.2 μmol/L PDTC for 24 hours it decreased to the lowest, nearly to the K562 cell level (p > 0.05); (3) the relative expression of both mdr-1 mRNA and P-gp in K562/AO₂ cells was more higher; the expressions of mdr-1 mRNA and P-gp both were inhibited in K562/AO₂ cell group treated with PDTC for 48 hours. It is concluded that the PDTC used as an inhibitor of NF-κB activity can partially reverse the multidrug resistance of K562/AO₂ cells, which mechanism can be associated with the down-regulation of mdr-1 mRNA and P-gp.Read more
We previously demonstrated that the novel guggulsterone derivative guggulsterone-52 (GG-52) inhibited the activation of nuclear factor (NF)-κB signaling in intestinal epithelial cells and had preventive and therapeutic effects on dextran sulfate sodium-induced acute colitis. This study investigates the anti-inflammatory effects of GG-52 on bone marrow-derived dendritic cells (BMDCs) and chronic colitis in IL-10(-/-) mice.
BMDCs were generated from the femurs of C57BL/6 wild-type and IL-10(-/-) mice. BMDCs were stimulated with lipopolysaccharide (LPS) in the presence or absence of GG-52. The effect of GG-52 on NF-κB signaling in BMDCs was examined by real-time RT-PCR for IL-12p40 and TNF-α gene expression, western blotting for IκBα degradation, and electrophoretic mobility shift assay. For in vivo studies, wild-type or IL-10(-/-) mice were treated with or without GG-52. Colitis was quantified by the evaluation of histopathological findings. Double immunofluorescence staining for CD11c and phosphorylated IκB kinase (IKK)-α was performed to detect IKK activation in DCs in colonic tissue.
GG-52 significantly inhibited LPS-induced IL-12p40 and TNF-α gene expression, IκBα degradation, and NF-κB DNA binding activity in BMDCs. In the IL-10(-/-) mouse model chronic colitis, administration of GG-52 significantly reduced the severity of colitis as assessed by histopathology, and suppressed IKK activation in DCs in colonic tissue.
These results indicate that the novel guggulsterone derivative GG-52 blocks NF-κB activation in BMDCs and ameliorates chronic colitis in IL-10(-/-) mice, which suggest that GG-52 is a potential therapeutic agent for inflammatory bowel diseases.Read more