Extracellular Regulated Kinase Inhibitor Research Articles

Involvement of ERK and Oxidative Stress in Airway Exposure to Cadmium Chloride Aggravates Airway Inflammation in Ovalbumin-Induced Asthmatic Mice.

Inhalation represents a significant route of cadmium (Cd) exposure, which is associated with an elevated risk of lung diseases. This research study aims to evaluate the impact of repeated low-dose cadmium inhalation on exacerbating airway inflammation induced by ovalbumin (OVA) in asthma-afflicted mice. Mice were grouped into four categories: control (Ctrl), OVA, cadmium chloride (CdCl2), and OVA + cadmium chloride (OVA + CdCl2). Mice in the OVA group displayed increased airway mucus secretion and peribronchial and airway inflammation characterized by eosinophil cell infiltration, along with elevated levels of Th2 cytokines (IL-4, IL-5, IL-13) in bronchoalveolar lavage fluids (BALFs). These parameters were further exacerbated in the OVA + CdCl2 group. Additionally, the OVA + CdCl2 group exhibited higher levels of the oxidative stress marker malondialdehyde (MDA), greater activity of glutathione peroxidase (GSH-Px), and higher phosphorylation of extracellular regulated kinase (ERK) in lung tissue. Treatment with U0126 (an ERK inhibitor) and α-tocopherol (an antioxidant) in the OVA + CdCl2 group resulted in reduced peribronchial and airway inflammation as well as decreased airway mucus secretion. These findings indicate that CdCl2 exacerbates airway inflammation in OVA-induced allergic asthma mice following airway exposure. ERK and oxidative stress are integral to this process, and the inhibition of these pathways significantly alleviates the adverse effects of CdCl2 on asthma exacerbation.

Periodontopathic BacteriumFusobacterium nucleatumAffects Matrix Metalloproteinase-9 Expression in Human Alveolar Epithelial Cells and Mouse Lung

Despite evidence of an association between pulmonary diseases and periodontopathic bacteria, the molecular mechanisms remain unknown. Matrix metalloproteinase-9 (MMP9) plays important roles in pneumonia, chronic obstructive pulmonary disease, and asthma; therefore, we assessed the effects of Fusobacterium nucleatum on MMP9 expression in mouse lung and A549 human alveolar epithelial cells. Heat-killed F. nucleatum was administered to the trachea of mice or added to A549 cell cultures. MMP9 expression was determined using real-time PCR and western blotting. The involvement of mitogen-activated protein kinases (MAPKs) and nuclear factor-κB (NF-κB) in MMP9 expression was examined. F. nucleatum induced expression of MMP9 in mouse lung and bronchoalveolar lavage fluid. In A549 cells, F. nucleatum induced production of MMP9 protein and mRNA in a density-dependent manner; this was inhibited by inhibitors of extracellular-regulated kinase 1/2 and NF-κB, but not of p38 and Jun N-terminal protein kinase. F. nucleatum may contribute to the onset of pulmonary diseases via MMP9 expression through extracellular-regulated kinase 1/2 and NF-κB activation.

Inhibition of extracellular regulated kinase (ERK)-1/2 signaling pathway in the prevention of ALS: Target inhibitors and influences on neurological dysfunctions.

Cell signal transduction pathways are essential modulators of several physiological and pathological processes in the brain. During overactivation, these signaling processes may lead to disease progression. Abnormal protein kinase activation is associated with several biological dysfunctions that facilitate neurodegeneration under different biological conditions. As a result, these signaling pathways are essential in understanding brain disorders' development or progression. Recent research findings indicate the crucial role of extracellular signal-regulated kinase-1/2 (ERK-1/2) signaling during the neuronal development process. ERK-1/2 is a key component of its mitogen-activated protein kinase (MAPK) group, controlling certain neurological activities by regulating metabolic pathways, cell proliferation, differentiation, and apoptosis. ERK-1/2 also influences neuronal elastic properties, nerve growth, and neurological and cognitive processing during brain injuries. The primary goal of this review is to elucidate the activation of ERK1/2 signaling, which is involved in the development of several ALS-related neuropathological dysfunctions. ALS is a rare neurological disorder category that mainly affects the nerve cells responsible for regulating voluntary muscle activity. ALS is progressive, which means that the symptoms are getting worse over time, and there is no cure for ALS and no effective treatment to avoid or reverse. Genetic abnormalities, oligodendrocyte degradation, glial overactivation, and immune deregulation are associated with ALS progression. Furthermore, the current review also identifies ERK-1/2 signaling inhibitors that can promote neuroprotection and neurotrophic effects against the clinical-pathological presentation of ALS. As a result, in the future, the potential ERK-1/2 signaling inhibitors could be used in the treatment of ALS and related neurocomplications.

Elucidation of Abnormal Extracellular Regulated Kinase (ERK) Signaling and Associations with Syndromic and Non-syndromic Autism.

Autism is a highly inherited and extremely complex disorder in which results from various cases indicate chromosome anomalies, unusual single-gene mutations, and multiplicative effects of particular gene variants, characterized primarily by impaired speech and social interaction and restricted behavior. The precise etiology of Autism Spectrum Disorder (ASD) is currently unclear. The extracellular signal-regulated kinase (ERK) signaling mechanism affects neurogenesis and neuronal plasticity during the development of the central nervous mechanism. In this regard, the pathway of ERK has recently gained significant interest in the pathogenesis of ASD. The mutation occurs in a few ERK components. Besides, the ERK pathway dysfunction lies in the upstream of modified translation and contributes to synapse pathology in syndromic types of autism. In this review, we highlight the ERK pathway as a target for neurodevelopmental disorder autism. In addition, we summarize the regulation of the ERK pathway with ERK inhibitors in neurological disorders. In conclusion, a better understanding of the ERK signaling pathway provides a range of therapeutic options for autism spectrum disorder.

Chloroquine ameliorates bone loss induced by d-galactose in male rats via inhibition of ERK associated osteoclastogenesis and antioxidant effect.

Chloroquine (CQ); a lysosomotropic agent used for decade ago as anti-malarial, was tested against aging induced osteoporosis. Osteoporosis in male rats was induced using d-galactose (D-gal) as a reducing sugar at a dose of 200 mg/kg/day; i.p. Osteoporotic rats were orally treated with CQ (10 mg/kg/day) for four successive weeks. Bone densitometry of tibia and femur were evaluated. Bone formation biomarkers; osteoprotegrin (OPG), bone specific alkaline phosphatse (BALP), and osteocalcin (OCN), and bone resorption biomarker; receptor activator of nuclear factor kappa-B ligand (RANKL), cathepsin-k (CTSK), tartrate-resistant acid phosphatase (TRAP) were estimated. Moreover, the expression of extracellular regulated kinase (ERK) in bone was determined. CQ ameliorated the bone detrimental changes induced by d-galactose. It enhanced bone health as revealed by measurement of bone densitometry, halted the activation of receptor activator of nuclear factor kappa-B ligand (RANKL) and reduced bone manifestation of ERK. Furthermore, CQ treatment abated serum cathepsin-k (CTSK) and serum tartrate-resistant acid phosphatase (TRAP) thus inhibited osteoclastogenesis and consequently restored the RANKL/OPG ratio. CQ demonstrated an antioxidant effect in bone where it increased both Catalase (CAT) and Superoxide dismutase (SOD). These CQ preserving effect in rats treated with d-galactose were confirmed by the histopathological examination. The present study points to the potential therapeutic effect of CQ as anti-osteoporotic agent possibly through its antioxidant effects and suppression of ERK associated osteoclastogenesis.

Lumican mediates HTB94 chondrosarcoma cell growth via an IGF‑IR/Erk1/2 axis.

Chondrosarcoma is a malignant bone tumor characterized by the production of a modified cartilage-type extracellular matrix (ECM). In the present study, the expression levels of the small leucine-rich proteoglycans (SLRPs), decorin, biglycan and lumican, were examined in the HTB94 human chondrosarcoma cell line. HTB94 cells were found to express and secrete the 3 SLRP members. RT-qPCR and western blot analysis demonstrated that lumican was the most abundantly secreted SLRP, whereas decorin and biglycan expression levels were low. The utilization of short interfering RNA specific for the decorin, biglycan, and lumican genes resulted in the efficient downregulation of the respective mRNA levels (P≤0.001). The growth of the HTB94 cells was stimulated by lumican (P≤0.001), whereas their migration and adhesion were not affected (P=NS). By contrast, these cellular functions were not sensitive to a decrease in low endogenous levels of decorin and biglycan. Lumicandeficiency significantly inhibited both basal and insulin-like growth factor I (IGF-I)-induced HTB94 cell growth (P≤0.001 andP≤0.01, respectively). These effects were executed through the insulin-like growth factor I receptor (IGF-IR), whose activation was markedly attenuated (P≤0.01) in lumican-deficient HTB94 cells. The downregulation of lumican induced the substantial inhibition of extracellular regulated kinase (ERK1/2) activation (P≤ 0.01), indicating that ERK1/2 is a necessary component of lumican/IGF-IR-mediated HTB94 cell proliferation. Moreover, the lumican-deficient cells exhibit increased mRNA levels of p53 (P≤0.05), suggesting that lumican facilitates HTB94 cell growth through an IGF-IR/ERK1/2/p53 signaling cascade. On the whole, the findings of the present study demonstrate that endogenous lumican is a novel regulator of HTB94 cell growth.

Functionally Selective Inhibition of the Oxytocin Receptor by Retosiban in Human Myometrial Smooth Muscle.

Novel small molecule inhibitors of the oxytocin receptor (OTR) may have distinct pharmacology and mode of action when compared with first-generation oxytocin antagonists when used for the prevention of preterm birth. The aim was to determine the mechanism of action of small molecule OTR antagonists retosiban and epelsiban compared with the currently used peptide-based compound atosiban. Human myometrial samples were obtained at cesarean section and subjected to pharmacological manipulations to establish the effect of antagonist binding to OTR on downstream signaling. Retosiban antagonism of oxytocin action in human myometrium was potent, rapid, and reversible. Inhibition of inositol 1,4,5-trisphosphate (IP3) production followed single-site competitive binding kinetics for epelsiban, retosiban, and atosiban. Retosiban inhibited basal production of IP3 in the absence of oxytocin. Oxytocin and atosiban but not retosiban inhibited forskolin, and calcitonin stimulated 3',5'-cyclic adenosine 5'-mono-phosphate (cAMP) production. Inhibition of cAMP was reversed by pertussis toxin. Oxytocin and atosiban, but not retosiban and epelsiban, stimulated extracellular regulated kinase (ERK)1/2 activity in a time- and concentration-dependent manner. Oxytocin and atosiban stimulated cyclo-oxygenase 2 activity and subsequent production of prostaglandin E2 and F2α. Prostaglandin production was inhibited by rofecoxib, pertussin toxin, and ERK inhibitor U0126. Oxytocin but not retosiban or atosiban stimulated coupling of the OTR to Gα q G-proteins. Oxytocin and atosiban but not retosiban stimulated coupling of the OTR to Gα i G-proteins. Retosiban and epelsiban demonstrate distinct pharmacology when compared with atosiban in human myometrial smooth muscle. Atosiban displays agonist activity at micromolar concentrations leading to stimulation of prostaglandin production.

Multi-Target Chemometric Modelling, Fragment Analysis and Virtual Screening with ERK Inhibitors as Potential Anticancer Agents.

Two isoforms of extracellular regulated kinase (ERK), namely ERK-1 and ERK-2, are associated with several cellular processes, the aberration of which leads to cancer. The ERK-1/2 inhibitors are thus considered as potential agents for cancer therapy. Multitarget quantitative structure–activity relationship (mt-QSAR) models based on the Box–Jenkins approach were developed with a dataset containing 6400 ERK inhibitors assayed under different experimental conditions. The first mt-QSAR linear model was built with linear discriminant analysis (LDA) and provided information regarding the structural requirements for better activity. This linear model was also utilised for a fragment analysis to estimate the contributions of ring fragments towards ERK inhibition. Then, the random forest (RF) technique was employed to produce highly predictive non-linear mt-QSAR models, which were used for screening the Asinex kinase library and identify the most potential virtual hits. The fragment analysis results justified the selection of the hits retrieved through such virtual screening. The latter were subsequently subjected to molecular docking and molecular dynamics simulations to understand their possible interactions with ERK enzymes. The present work, which utilises in-silico techniques such as multitarget chemometric modelling, fragment analysis, virtual screening, molecular docking and dynamics, may provide important guidelines to facilitate the discovery of novel ERK inhibitors.

Naringenin-induced HO-1 ameliorates high glucose or free fatty acids-associated apoptosis via PI3K and JNK/Nrf2 pathways in human umbilical vein endothelial cells

Naringenin (NG), a flavanone extracted from various plants, has potent vasoprotective effects likely related to the induction of heme oxygenase-1 (HO-1). In the current study, we investigated mechanisms underlying the effect of NG on HO-1 expression and high glucose (HG)- or free fatty acids (FFA)-induced apoptosis in human umbilical vein endothelial cells (HUVECs). First, we found that HUVECs exposed to NG exhibited enhanced HO-1 expression in a concentration- and time-dependent manner. Moreover, HUVECs treated with NG exhibited activation of phosphoinositide 3 kinase (PI3K)/Akt, extracellular-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK). LY294002 (a PI3K inhibitor) and SP600125 (a JNK inhibitor) reduced NG-induced HO-1 expression, whereas BIRB796 (a p38 inhibitor) and PD98059 (an ERK inhibitor) had no effect. The cytoprotective effects of NG were correlated with activation of the transcription factor NF-E2-related factor 2 (Nrf2), a critical regulator of HO-1 expression. Indeed, the results of our experiments using LY294002 and SP600125 indicated that NG may stimulate Nrf2 through PI3K/Akt and JNK pathway activation. Moreover, treatment of HUVECs with Nrf2 siRNA decreased NG-induced HO-1 expression. Finally, pretreatment of HUVECs with NG remarkably reduced HG- or FFA-induced cell apoptosis, and this effect was greatly abrogated in the presence of SnPP (an HO-1 inhibitor). Above all, our data show that NG increased HO-1 expression and reduced HG- or FFA-induced cell apoptosis in HUVECs by upregulating PI3K, JNK, and Nrf2 pathways, which may confer an adaptive survival response in diabetes-induced vascular injury.

Oleanolic acid attenuates cisplatin-induced nephrotoxicity in mice and chemosensitizes human cervical cancer cells to cisplatin cytotoxicity

Oleanolic acid (OA) is a natural triterpenoid that possesses numerous beneficial health effects such as antioxidant, anti-inflammatory and anti-apoptotic activities. In this study, we investigated the therapeutic effect of OA (10 and 40 mg/kg) on cisplatin (CP)-induced (13 mg/kg) nephrotoxicity. Treatment with OA 40 mg/kg once daily for 2 days, 48 h after CP-intoxication, ameliorated the increased serum markers and histological features of kidney injury. CP administration increased renal expression of antioxidant and anti-inflammatory markers, which was reduced by OA. The increase in proapoptotic caspase-3 and -9 activations, with concomitant increase in poly (ADP-ribose) polymerase (PARP) cleavage, were dose-dependently inhibited by OA. Treatment with OA also ameliorated microtubule-associated protein 1A/1B-light chain 3B (LC3B)-II and autophagy-related protein (Atg) 5 expression induced by CP. The suppression of CP-induced oxidative stress, apoptosis, autophagy and inflammatory response by OA coincided with the inhibition of extracellular-regulated kinase (ERK) 1/2, signal transducer and activator of transcription (STAT) 3 and nuclear factor-kappa B (NF-κB). Interestingly, OA increased CP cytotoxicity in HeLa cervical cancer cells by inducing cytotoxic autophagy. The chemosensitization of HeLa cells to CP suggests a potential beneficial effect of OA in cervical cancer patients due to reduced CP dosage requirements, which requires further investigation.

Epidermal Growth Factor Receptor Regulation of Ewing Sarcoma Cell Function

Objective: Ewing sarcoma (ES) is a type of childhood cancer probably arising from stem mesenchymal or neural crest cells. The epidermal growth factor receptor (EGFR) acts as a driver oncogene in many types of solid tumors. However, its involvement in ES remains poorly understood. Methods: Human SK-ES-1 and RD-ES ES cells were treated with EGF, the EGFR inhibitor tyrphostin (AG1478), or phosphoinositide 3-kinase (PI3K) or extracellular-regulated kinase (ERK)/mitogen-activated kinase (MAPK) inhibitors. Cell proliferation survival, cycle, and senescence were analyzed. The protein content of possible targets of EGFR manipulation was measured by Western blot. Results: Cell proliferation and survival were increased by EGF and inhibited by AG1478. The EGFR inhibitor also altered the cell cycle, inducing arrest in G1 and increasing the sub-G1 population, reduced polyploidy and increased the population of senescent cells. In addition, AG1478 reduced the levels of phosphorylated AKT (p-AKT), ERK, p-ERK, cyclin D1, and brain-derived neurotrophic factor (BDNF), while enhancing p53 levels. Cell proliferation was also impaired by inhibitors of PI3K or ERK, alone or combined with AG1478. Conclusions: Our findings reveal novel aspects of EGFR regulation of ES cells and provide early evidence for antitumor activities of EGFR inhibitors in ES.

Andrographolide suppresses the migratory ability of human glioblastoma multiforme cells by targeting ERK1/2-mediated matrix metalloproteinase-2 expression.

Glioblastoma multiforme (GBM) can be a fatal tumor because of difficulties in treating the related metastasis. Andrographolide is the bioactive component of the Andrographis paniculata. Andrographolide possesses the anti-inflammatory activity and inhibits the growth of various cancers; however, its effect on GBM cancer motility remains largely unknown. In this study, we examined the antimetastatic properties of andrographolide in human GBM cells. Our results revealed that andrographolide inhibited the invasion and migration abilities of GBM8401 and U251 cells. Furthermore, andrographolide inhibited matrix metalloproteinase (MMP)-2 activity and expression. Real-time PCR and promoter activity assays indicated that andrographolide inhibited MMP-2 expression at the transcriptional level. Such inhibitory effects were associated with the suppression of CREB DNA-binding activity and CREB expression. Mechanistically, andrographolide inhibited the cell motility of GBM8401 cells through the extracellular-regulated kinase (ERK) 1/2 pathway, and the blocking of the ERK 1/2 pathway could reverse MMP-2-mediated cell motility. In conclusion, CREB is a crucial target of andrographolide for suppressing MMP-2-mediated cell motility in GBM cells. Therefore, a combination of andrographolide and an ERK inhibitor might be a good strategy for preventing GBM metastasis.

Gallic acid, a natural polyphenol, protects against tert-butyl hydroperoxide- induced hepatotoxicity by activating ERK-Nrf2-Keap1-mediated antioxidative response

Gallic acid (GA), a natural polyphenol, has been shown to exert a variety of heath promoting effects. We herein investigated the critical role of nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated antioxidant response in the protection of GA against tert-butyl hydroperoxide (t-BHP)-induced hepatotoxicity in L02 cells. Pretreatment of GA prevented the hepatocytotoxicity induced by t-BHP, as evidenced by the facts that GA suppressed t-BHP-induced cytotoxicity and reactive oxygen species (ROS) generation. GA induced nuclear translocation of Nrf2 along with expression of target proteins, including heme oxygenase-1 (HO-1) and glutamate cysteine ligase catalytic modify subunit (GCLC), and increased intracellular glutathione (GSH) content. Additionally, GA induced phosphorylated activation of extracellular regulated kinase (ERK), and ERK inhibitor PD98059 partially decreased GA-induced hepatoprotection, and downregulated the increased protein expressions of Nrf2, GCLC and HO-1 induced by GA. Interestingly, we found that GA could enhance the thermal stability of Keap1, which indicated the potential interaction between GA and Keap1. Furthermore, molecular docking indicated that GA possibly competed with Nrf2 for binding to Keap1. Collectively, GA effectively protects against t-BHP-induced hepatotoxicity via inducing ERK/Nrf2-mediated antioxidative signaling pathway. Meanwhile, GA disturbs protein-protein interaction between Keap1 and Nrf2 which might also contribute to nuclear translocation of Nrf2.

Cyanidin-3-O-glucoside promotes the biosynthesis of progesterone through the protection of mitochondrial function in Pb-exposed rat leydig cells

Cyanidin-3-O-glucoside (C3G) is an anthocyanin that has been reported to reduce the toxicity of heavy metals. In the present study, the protection effects of C3G on the biosynthesis of progesterone, the precursor of testosterone, against lead (Pb) in R2C rat Leydig cells were examined. Treatment of R2C cells with 100 μM Pb resulted in a significant decrease in progesterone production. After being cultured in a medium containing C3G and Pb, R2C cells exhibited an increase in progesterone concentration compared with the Pb treatment, as a result of up-regulation of the expression of the steroidogenic enzymes steroidogenic acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β-HSD) and cytochrome P450 enzyme cholesterol side chain cleavage enzyme (CYP11A1). Pb-induced inhibition of extracellular regulated Kinase 1/2 (ERK 1/2) phosphorylation and down-regulation of protein kinase A (PKA) expression were alleviated by C3G. In addition, Pb-induced reactive oxygen species (ROS) overproduction led to mitochondrial depolarization, resulting in a decrease in progesterone biosynthesis, while C3G intervention reduced the ROS level and increased progesterone production. In conclusion, C3G may alleviate the Pb-induced decrease of progesterone biosynthesis by modulating the dysfunction of mitochondria, including decreasing oxidative stress and regulating expression of steroidogenic enzyme proteins.

Erlotinib attenuates the progression of chronic kidney disease in rats with remnant kidney.

Increasing evidence indicates that epidermal growth factor receptor (EGFR) has a pathogenic role in renal fibrosis. Currently no effective treatment can completely halt the progression of chronic kidney disease (CKD). This study was undertaken to investigate the renoprotective effects of erlotinib, a tyrosine kinase inhibitor that can block EGFR activity in the progression of CKD and the mechanisms involved. Sprague Dawley rats with 5/6 nephrectomy were administered either erlotinib or vehicle from 2 weeks after surgery and for a period of 8 weeks. Blood pressure, proteinuria and serum creatinine were measured periodically. Renal morphological investigations were performed at sacrifice. In vitro, we used normal human mesangial cells (NHMCs) and human proximal tubular cells to investigate the inhibitory effects of erlotinib on renal fibrosis-associated signaling pathways by western blotting. Erlotinib treatment significantly blunted the progression of CKD as evidenced by reduced levels of serum creatinine, proteinuria and renal cortical profibrogenic genes and scores of glomerulosclerosis and tubulointerstitial damage. Tubulointerstitial macrophage infiltration and multiple pro-inflammatory cytokine gene expression levels were also attenuated by erlotinib treatment. In vitro, heparin-binding epidermal growth factor-like growth factor-induced Akt and extracellular-regulated kinase (ERK) 1/2 activation in normal human mesangial cells and human proximal tubular cells was inhibited by pretreatment with erlotinib. EGFR blocking by erlotinib protected against renal fibrosis in 5/6 nephrectomized rats via inhibition of Akt and ERK 1/2 signaling pathways, which are associated with renal fibrosis. Erlotinib also has anti-inflammatory properties, which may contribute to its renoprotective effects. Erlotinib represents a potential novel therapeutic strategy for the treatment of CKD.

A Rationale for Targeting Extracellular Regulated Kinases ERK1 and ERK2 in Glioblastoma.

Glioblastoma (GBM) is the most common malignant primary brain tumor. It still carries a grim prognosis and new therapies are needed. This review summarizes the current status of mechanistic insights into the function of extracellular regulated kinase (ERK) and its potential as a therapeutic target for patients with GBM. Currently, some promising ERK inhibitors are in clinical trials in tumor entities other than GBM. Here, we provide a comprehensive overview on the functions of ERK1/2 in GBM and a rationale for treatment of GBM with ERK inhibitors.

Induction of Nrf2-mediated phase II detoxifying/antioxidant enzymes in vitro by chitosan-caffeic acid against hydrogen peroxide-induced hepatotoxicity through JNK/ERK pathway.

Chemical modification of chitosan is a promising method for the improvement of biological activity. In this study, chitosan-caffeic acid (CCA) was prepared and its in vitro hepatoprotective ability against hydrogen peroxide-induced hepatic damage in liver cells was evaluated. Treatment with CCA (50-400µg/mL) did not show cytotoxicity and also significantly (p<0.05) recovered cell viability against 650µM hydrogen peroxide-induced hepatotoxicity. CCA treatment attenuated reactive oxygen species generation and lipid peroxidation in addition to increasing cellular glutathione level in cultured hepatocytes. To validate the underlying mechanism, antioxidant and phase II detoxifying enzyme expressions, which are mediated by NF-E2-related factor 2 (Nrf2) activation, were analyzed and CCA treatment was found to increase the expression of superoxide dismutase-1 (SOD-1), glutathione reductase (GR), heme oxygenase-1 (HO-1), and NAD(P)H:quinine oxidoreductase 1 (NQO1). CCA treatment resulted in increased Nrf2 nuclear translocation. The phosphorylation of extracellular regulated kinase (ERK), c-Jun NH2-terminal kinase (JNK), and p38 mitogen-activated protein kinase (MAPK) by CCA treatment contributed to Nrf2 activation. Pharmacological blockade of ERK, JNK, and p38 MAPK revealed that SP600125 (JNK inhibitor) and PD98059 (ERK inhibitor) treatment reduced Nrf2 translocation into the nucleus while SB203580 (p38 inhibitor) exhibited weak inhibition. Collectively, CCA protects liver cells against hydrogen peroxide-induced injury and this ability is attributed to the induction of antioxidants and phase II detoxifying enzymes that are mediated by Nrf2 translocation via JNK/ERK signaling.

Curcumin potentiates antitumor activity of cisplatin in bladder cancer cell lines via ROS-mediated activation of ERK1/2.

Resistance of bladder cancer to cisplatin is a major obstacle to successful treatment. In the current study, we investigated the apoptotic effects of curcumin and cisplatin co-treatment in 253J-Bv(p53 wild-type) and T24(p53 mutant) bladder cancer. We found that curcumin and cisplatin co-treatment primarily targets reactive oxygen species(ROS) and extracellular regulated kinase(ERK) signaling during the apoptosis induction in bladder cancer. The apoptosis rate in 253J-Bv and T24 cells co-treated with curcumin and cisplatin was increased compared to that in cells exposed to single-agent treatment conditions. Also, caspase-3 activation and ROS production were observed in both cells treated with curcumin and cisplatin, together with upregulation of p-MEK and p-ERK1/2 signaling. NAC(ROS scavenger) and U0126(ERK inhibitor) inhibited apoptosis induced by curcumin and cisplatin. In addition, when 253J-Bv cells were co-treated with curcumin and cisplatin, p53 and p21 expression levels were markedly increased when compared to controls. Unlike 253J-Bv cells, T24 cells were co-treated with curcumin and cisplatin revealed an induction of apoptosis through decreased p-signal transducer and activator of transcription 3(STAT3) expression. Moreover, pretreatment with U0126 suppressed curcumin and cisplatin-induced upregulation of p53, p21, and p-STAT3 and downregulation of survival proteins in both cells. In conclusion, co-treatment with curcumin and cisplatin synergistically induced apoptosis through ROS-mediated activation of ERK1/2 in bladder cancer.

Changes in gene expression of histone modification enzymes in rat granulosa cells undergoing luteinization during ovulation.

BackgroundThe ovulatory LH surge rapidly alters the expression of steroidogenesis-related genes such as steroidogenic acute regulatory protein (StAR) in granulosa cells (GCs) undergoing luteinization. We recently reported that histone modifications contribute to these changes. Histone modifications are regulated by a variety of histone modification enzymes. This study investigated the changes in gene expression of histone modification enzymes in rat GCs undergoing luteinization after the induction of ovulation. The extracellular regulated kinase (ERK)-1/2 is a mediator in the intracellular signaling pathway stimulated by the ovulatory LH surge and regulates the expression of a number of genes in GCs. We further investigated whether ERK-1/2 is involved in the regulation of the histone modification at the StAR promoter region in GCs undergoing luteinization.ResultsGCs were obtained from rats treated with equine chorionic gonadotropin (CG) before (0 h) and after human (h) CG injection. The expressions of 84 genes regulating histone modifications or DNA methylation were measured using a PCR array. Five genes (HDAC4, HDAC10, EZH2, SETDB2, and CIITA) were identified as histone acetylation- or histone methylation-related genes, and were significantly altered after hCG injection. None of the genes were related to DNA methylation. mRNA levels of EZH2, SETDB2, HDAC4, and HDAC10 decreased and CIITA mRNA levels increased 4 or 12 h after hCG injection.GCs isolated after eCG injection were incubated with hCG for 4 h to induce luteinization. StAR mRNA levels were significantly increased by hCG accompanied by the increase in H3K4me3 of the StAR promoter region. StAR mRNA expression was inhibited by the ERK inhibitor with the significant decrease of H3K4me3. These results suggest that hCG increases StAR gene expression through the ERK-1/2-mediated signaling which is also associated with histone modification of the promoter region.ConclusionsGene expressions of histone modification enzymes change in GCs undergoing luteinization after ovulation induction. This change may play important roles in regulating the expression of various genes during the early stage of luteinization, which may be critical for the subsequent corpus luteum formation.

Saikosaponin-D Reduces H2O2-Induced PC12 Cell Apoptosis by Removing ROS and Blocking MAPK-Dependent Oxidative Damage

Neuronal oxidative stress (OS) injury has been proven to be associated with many neurodegenerative diseases, and thus, antioxidation treatment is an effective method for treating these diseases. Saikosaponin-D (SSD) is a sapogenin extracted from Bupleurum falcatum and has been shown to have many pharmacological activities. The main purpose of this study was to investigate whether and how SSD protects PC12 cells from H2O2-induced apoptosis. The non-toxic level of SSD significantly mitigated the H2O2-induced decrease in cell viability, reduced the apoptosis rate, improved the nuclear morphology, and reduced caspase-3 activation and poly ADP-ribose polymerase (PARP) cleavage. Additionally, exogenous H2O2-induced apoptosis by damaging the intracellular antioxidation system. SSD significantly slowed the H2O2-induced release of malonic dialdehyde (MDA) and lactate dehydrogenase and increased the activity of superoxide dismutase (SOD) and the total antioxidant capacity, thereby reducing apoptosis. More importantly, SSD effectively blocked H2O2-induced phosphorylation of extracellular-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 mitogen-activated protein kinase (p38MAPK), and specific inhibitors of ERK, JNK, and p38-reduced OS injury and apoptosis, suggesting that SSD reduces OS injury and apoptosis via MAPK signalling pathways. Finally, we confirmed that SSD significantly reduced H2O2-induced reactive oxygen species (ROS) accumulation, and the ROS inhibitor blocked the apoptosis caused by MAPK activation and cellular oxidative damage. In short, our study confirmed that SSD reduces H2O2-induced PC12 cell apoptosis by removing ROS and blocking MAPK-dependent oxidative damage.