Increased expression of mitogen-activated protein kinase and its upstream regulating signal in human gastric cancer

AIM: To investigate the expression of mitogen-activated protein kinases (MAPKs) and its upstream protein kinase in human gastric cancer and to evaluate the relationship between protein levels and clinicopathological parameters. METHODS: Western blot was used to measure the expression of extracellular signal-regulated kinase (ERK)-1, ERK-2, ERK-3, p38 and mitogen or ERK activated protein kinaseMEK-1 proteins in surgically resected gastric carcinoma, adjacent normal mucosa and metastatic lymph nodes from 42 patients. Immunohistochemistry was employed for their localization. RESULTS: Compared with normal tissues, the protein levels of ERK-1 (integral optical density value 159 526?5 760 vs 122 807±65 515, P= 0.001), ERK-2 (168 471±95 051 vs 120 469±72 874, P<0.001), ERK-3 (118 651±71 513 vs 70 934±68 058,P<0.001), P38 (104 776±51 650 vs 82 930±40 392, P= 0.048) and MEK-1 (116 486±45 725 vs 101 434±49 387, P = 0.027) were increased in gastric cancer tissues. Overexpression of ERK-3 was correlated to TNM staging [average ratio of integral optic density (IOD)tumor: IODnormal in TNM I, II, III, IV tumors was 1.43±0.34, 5.08±3.74, 4.99±1.08, 1.44±1.02, n = 42, P= 0.023] and serosa invasion (4.31±4.34 vs 2.00±2.03, P = 0.037). In poorly differentiated cancers (n = 33), the protein levels of ERK-1 and ERK-2 in stage III and IV tumors were higher than those in stage I and II tumors (2.64+3.01 vs 1.01±0.33, P= 0.022; 2.05±1.54 vs1.24±0.40, P= 0.030). Gastric cancer tissues with either lymph node involvement (2.49±2.91 vs1.03±0.36, P= 0.023; 1.98±1.49vs1.24±0.44, P= 0.036) or serosa invasion (2.39±2.82 vs 1.01±0.35, P= 0.022; 1.95±1.44 vs1.14±0.36, P=0.015) expressed higher protein levels of ERK-1 and ERK-2. In Borrmann II tumors, expression of ERK-2 and ERK-3 was increased compared with Borrmann III tumors (2.57±1.86 vs1.23±0.60, P= 0.022; 5.50±5.05 vs1.83±1.21, P= 0.014). Borrmann IV tumors expressed higher p38 protein levels. No statistically significant difference in expression of MAPKs was found when stratified to tumor size or histological grade (P>0.05). Protein levels of ERK-2, ERK-3 and MEK-1 in metastatic lymph nodes were 2-7 folds higher than those in adjacent normal mucosa. The immunohistochemistry demonstrated that ERK-1, ERK-2, ERK-3, p38 and MEK-1 proteins were mainly localized in cytoplasm. The expression of MEK-1 in gastric cancer cells metastasized to lymph nodes was higher than that of the primary site. CONCLUSION: MAPKs, particularly ERK subclass are overexpressed in the majority of gastric cancers. Overexpression of ERKs is correlated to TNM staging, serosa invasion, and lymph node involvement. The overexpression of p38 most likely plays a prominent role in certain morphological subtypes of gastric cancers. MEK-1 is also overexpressed in gastric cancer, particularly in metastatic lymph nodes. Upregulation of MARK signal transduction pathways may play an important role in tumorigenesis and metastatic potential of gastric cancer.

Physiological roles of mitogen-activated-protein-kinase-activated p38-regulated/activated protein kinase

Mitogen-activated protein kinases(MAPKs)are a family of proteins that constitute signaling pathways involved in processes that control gene expression,cell division, cell survival,apoptosis,metabolism,differentiation and motility.The MAPK pathways can be divided into conventional and atypical MAPK pathways.The first group converts a signal into a cellular response through a relay of three consecutive phosphorylation events exerted by MAPK kinase kinases,MAPK kinase,and MAPK.Atypical MAPK pathways are not organized into this three-tiered cascade.MAPK that belongs to both conventional and atypical MAPK pathways can phosphorylate both non-protein kinase substrates and other protein kinases.The latter are referred to as MAPK-activated protein kinases.This review focuses on one such MAPK-activated protein kinase,MAPK-activated protein kinase 5(MK5)or p38-regulated/activated protein kinase(PRAK).This protein is highly conserved throughout the animal kingdom and seems to be the target of both conventional and atypical MAPK pathways.Recent findings on the regulation of the activity and subcellular localization,bona fide interaction partners and physiological roles of MK5/PRAK are discussed.

Effects of invigorating-spleen and anticancer prescription on extracellular signal-regulated kinase/mitogen-activated protein kinase signaling pathway in colon cancer mice model

BACKGROUND Colon cancer(CC)is one of the most common malignant tumors in the gastrointestinal system.Overall,CC had the third highest incidence but the second highest mortality rate globally in 2020.Nowadays,CC is mainly treated with capecitabine chemotherapy regimen,supplemented by radiotherapy,immunotherapy and targeted therapy,but there are still limitations,so Chinese medicine plays an important role.AIM To investigate the effects of invigorating-spleen and anticancer prescription(ISAP)on body weight,tumor inhibition rate and expression levels of proteins in extracellular-signal-regulated kinase(ERK)/mitogen-activated protein kinase(MAPK)signaling pathway in CC mice model.METHODS The CC mice model were established and the mice were randomly divided into 5 groups,including the control group,capecitabine group,the low-dose,mediumdose and high-dose groups of ISAP,with 8 mice in each group,respectively.After 2 weeks of intervention,the body weight and tumor inhibition rate of mice were observed,and the expression of RAS,ERK,phosphorylated ERK(p-ERK),C-MYC and matrix metalloproteinase 2(MMP2)proteins in the tissues of tumors were detected.RESULTS Compared with the control group,the differences of body weight before and after treatment was much smaller in the groups of ISAP,with the smallest difference in the high-dose group of ISAP,while the capecitabine group had the greatest difference,indicating ISAP had a significant inhibiting effect on the growth of transplanted tumor in mice.The expression of RAS protein was decreased in the low-and medium-dose groups of ISAP,and the change of p-ERK was significant in the medium-and high-dose groups of ISAP.MMP2 protein expression was significantly decreased in both the low-dose and medium-dose groups of ISAP.There were no significant changes in ERK in the ISAP group compared to the capecitabine group,while RAS,MMP2,and C-MYC protein expression were reduced in the ISAP group.The expression level of C-MYC protein decreased after treated with ISAP,and the decrease was the most significant in the medium-dose group of ISAP.CONCLUSION ISAP has a potential inhibiting effect on transplanted tumor in mice,and could maintain the general conditions,physical strength and body weight of mice.The expression levels of RAS,p-ERK,MMP2 and c-myc were also decreased to a certain extent.By inhibiting the expression of upstream proteins,the expression levels of downstream proteins in ERK/MAPK signaling pathway were significantly decreased.Therefore,it can be concluded that ISAP may exert an anti-tumor effect by blocking the ERK/MAPK signaling pathway and inhibiting the expression of MMP2 and c-myc proteins.

Optimized new Shengmai powder(优化新生脉散方) inhibits myocardial fibrosis in heart failure by regulating the rat sarcoma/rapidly accelerated fibrosarcoma/mitogen-activated protein kinase kinase/extracellular regulated protein kinases signaling pathway

OBJECTIVE: Exploring the effect of Optimized New Shengmai powder(优化新生脉散方, ONSMP) on myocardial fibrosis in heart failure(HF) based on rat sarcoma(RAS)/rapidly accelerated fibrosarcoma(RAF)/mitogen-activated protein kinase kinase(MEK)/extracellular regulated protein kinases(ERK) signaling pathway. METHODS: Randomized 70 Sprague-Dawley rats into sham(n = 10) and operation(n = 60) groups, then established the HF rat by ligating the left anterior descending branch of the coronary artery. We randomly divided the operation group rats into the model, ONSMP [including low(L), medium(M), and high(H) dose], and enalapril groups. After the 4-week drug intervention, echocardiography examines the cardiac function and calculates the ratios of the whole/left heart to the rat's body weight. Finally, we observed the degree of myocardial fibrosis by pathological sections, determined myocardium collagen(COL) Ⅰ and COL Ⅲ content by enzyme-linked immunosorbent assay, detected the m RNA levels of COL Ⅰ, COL Ⅲ, α-smooth muscle actin(α-SMA), and c-Fos proto-oncogene(c-Fos) by universal real-time, and detected the protein expression of p-RAS, p-RAF, p-MEK1/2, p-ERK1/2, p-ETS-like-1 transcription factor(p-ELK1), p-c-Fos, α-SMA, COL Ⅰ, and COL Ⅲ by Western blot. RESULTS: ONSMP can effectively improve HF rat's cardiac function, decrease cardiac organ coefficient, COL volume fraction, and COL Ⅰ/Ⅲ content, down-regulate the m RNA of COL Ⅰ/Ⅲ, α-SMA and c-Fos, and the protein of p-RAS, p-RAF, p-MEK1/2, p-ERK1/2, p-ELK1, c-Fos, COL Ⅰ/Ⅲ, and α-SMA. CONCLUSIONS: ONSMP can effectively reduce myocardial fibrosis in HF rats, and the mechanism may be related to the inhibition of the RAS/RAF/MEK/ERK signaling pathway.

Imbalanced expression of mitogen-activated protein kinase phosphatase-1 and phosphorylated extracellular signal-regulated kinases in lung squamous cell carcinoma

Objective： Mitogen-activated protein kinases （MAPKs） are correlated with a more malignant phenotype in many cancers. This study was designed to evaluate the predictive value of the expression of MAPK phosphatase-1 （MKP-1） and phosphorylated extracellular signal-regulated kinase 1/2 （p-ERKl/2）, as the key regulatory mechanism of the MAPKs, in lung squamous cell carcinoma （SCC）. Methods： We assessed the expressions of MKP-1 and p-ERK1/2 in twenty subjects at different differentiation degree of SCC and five normal lungs by immunohistochemistry and real-time reverse transcriptase polymerase chain reaction （RT-PCR） analysis. Results： Immunohistochemistry and real-time RT-PCR assay showed that the expression of MKP-1 was gradually decreased as tissue type went from normal lung tissues to increasingly undifferentiated carcinoma, and it was negatively correlated with tumor differentiation （P〈0.01）. However, the expression of p-ERK1/2 or ERKl/2 was gradually increased as tissue type went from normal lung tissues to increasingly undifferentiated carcinoma, and it was positively correlated with tumor differentiation （P〈0.01）. Conclusions： Our data indicates the relevance of MKP-1 and p-ERK1/2 in SCC as a potential positive and negative prognostic factor. The imbalanced expression of MKP-1 and p-ERKl/2 may play a role in the development of SCC and these two molecules may be new targets for the therapy and prognosis of SCC.

Mitogen activated protein kinase signaling pathways participate in the active principle region of Buyang Huanwu decoction-induced differentiation of bone marrow mesenchymal stem cells

Our preliminary studies confirmed that an active principle region of Buyang Huanwu decoction, comprising alkaloid, polysaccharide, aglycon, glucoside and volatile oil, can induce bone marrow mesenchymal stem cell differentiation into neurons. Mitogen-activated protein kinase signaling was identified as one of the key pathways underlying this differentiation process. The present study shows phosphorylated extracellular signal-regulated protein kinase and phosphorylated p38 protein expression was increased after differentiation. Cellular signaling pathway blocking agents, PD98059 and SB203580, inhibited extracellular signal-regulated protein kinase and p38 in mitogen-activated protein kinase signaling pathways respectively, mRNA and protein expression of the neuronal marker, neuron specific enolase, and neural stem cell marker, nestin, were decreased in bone marrow mesenchymal stem cells after treatment with the active principle region of Buyang Huanwu decoction. Experimental findings indicate that, extracellular signal-regulated protein kinase and p38 in mitogen-activated protein kinase signaling pathways participate in bone marrow mesenchymal stem cell differentiation into neuron-like cells, induced by the active principle region of Buyang Huanwu decoction.

Involvement of MAPK/ERK kinase-ERK pathway in exogenous bFGF-induced Egr-1 binding activity enhancement in anoxia-reoxygenation injured astrocytes

Objective Intravenous administration of basic fibroblast growth factor （bFGF） is effective to reduce the volume of cerebral infract due to ischemia. This study was designed to investigate the molecular mechanism, especially the signal transduction pathways, involved in this protective role of bFGF. Methods Anoxia-reoxygenation treated atrocytes were used to study the role of mitogen-activated protein kinase/extracellular signal-regulated kinase kinase （MAPK/ERK kinase, MEK）-ERK signaling pathway after exogenous bFGF administration by Western blot. Electrophoretic mobile shift assay was used to detect the binding activity of early growth response factor-1 （Egr-1）, an important transcription factor for endogenous bFGF. Results bFGF could protect some signal transduction proteins from the oxygen-derived free radicals induced degradation. ERK1/2 was activated and involved in Egr-1 binding activity enhancement induced by exogenous bFGF. Conclusion MEK-ERK MAPK cascade may be an important signal transduction pathway contributed to bFGF induced enhancement of Egr-1 binding activity in anoxia-reoxygenation injured astrocytes.

Neuroprotective effects of cold-inducible RNA-binding protein during mild hypothermia on traumatic brain injury

Cold-inducible RNA-binding protein（CIRP）, a key regulatory protein, could be facilitated by mild hypothermia in the brain, heart and liver. This study observed the effects of mild hypothermia at 31 ± 0.5℃ on traumatic brain injury in rats. Results demonstrated that mild hypothermia suppressed apoptosis in the cortex, hippocampus and hypothalamus, facilitated CIRP m RNA and protein expression in these regions, especially in the hypothalamus. The anti-apoptotic effect of mild hypothermia disappeared after CIRP silencing. There was no correlation between mitogen-activated extracellular signal-regulated kinase activation and CIRP silencing. CIRP silencing inhibited extracellular signal-regulated kinase-1/2 activation. These indicate that CIRP inhibits apoptosis by affecting extracellular signal-regulated kinase-1/2 activation, and exerts a neuroprotective effect during mild hypothermia for traumatic brain injury.

Development of small molecule extracellular signal-regulated kinases(ERKs) inhibitors for cancer therapy

The mitogen-activated protein kinase(MAPK)/extracellular signal-regulated kinase 1/2(ERK1/2) signaling pathway is widely activated by a variety of extracellular stimuli, and its dysregulation is associated with the proliferation, invasion, and migration of cancer cells. ERK1/2 is located at the distal end of this pathway and rarely undergoes mutations, making it an attractive target for anticancer drug development. Currently, an increasing number of ERK1/2 inhibitors have been designed and synthesized for antitumor therapy, among which representative compounds have entered clinical trials. When ERK1/2 signal transduction is eliminated, ERK5 may provide a bypass route to rescue proliferation, and weaken the potency of ERK1/2 inhibitors. Therefore, drug research targeting ERK5 or based on the compensatory mechanism of ERK5 for ERK1/2 opens up a new way for oncotherapy. This review provides an overview of the physiological and biological functions of ERKs, focuses on the structure-activity relationships of small molecule inhibitors targeting ERKs, with a view to providing guidance for future drug design and optimization, and discusses the potential therapeutic strategies to overcome drug resistance.

Synthetic lethal short hairpin RNA screening reveals that ring finger protein 183 confers resistance to trametinib in colorectal cancer cells

Background: The mitogen-activated extracellular signal-regulated kinase 1/2(MEK1/2) inhibitor trametinib has shown promising therapeutic effects on melanoma, but its efficacy on colorectal cancer(CRC) is limited. Synthetic lethality arises with a combination of two or more separate gene mutations that causes cell death, whereas individual mutations keep cells alive. This study aimed to identify the genes responsible for resistance to trametinib in CRC cells,using a synthetic lethal short hairpin RNA(shRNA) screening approach.Methods: We infected HT29 cells with a pooled lentiviral shRNA library and applied next-generation sequencing to identify shRNAs with reduced abundance after 8-day treatment of 20 nmol/L trametinib. HCT116 and HT29 cells were used in validation studies. Stable ring finger protein 183(RNF183)-overexpressing cell lines were generated by pcDNA4-myc/his-RNF183 transfection. Stable RNF 183-knockdown cell lines were generated by infection of lentiviruses that express RNF183 shRNA, and small interference RNA(siRNA) was used to knock down RNF183 transiently.Quantitative real-time PCR was used to determine the mRNA expression. Western blotting, immunohistochemical analysis, and enzyme-linked immunosorbent assay(ELISA) were used to evaluate the protein abundance. MTT assay,colony formation assay, and subcutaneous xenograft tumor growth model were used to evaluate cell proliferation.Results: In the primary screening, we found that the abundance of RNF183 shRNA was markedly reduced after treatment with trametinib. Trametinib induced the expression of RNF183, which conferred resistance to drug-induced cell growth repression and apoptotic and non-apoptotic cell deaths. Moreover, interleukin-8(IL-8) was a downstream gene of RNF183 and was required for the function of RNF183 in facilitating cell growth. Additionally, elevated RNF183 expression partly reduced the inhibitory effect of trametinib on IL-8 expression. Finally, xenograft tumor model showed the synergism of RNF183 knockdown and trametinib in repressing the growth of CRC cells in vivo.Conclusion: The RNF183-IL-8 axis is responsible for the resistance of CRC cells to the MEK1/2 inhibitor trametinib and may serve as a candidate target for combined therapy for CRC.

Transthyretin—A Key Gene Involved in Regulating Learning and Memory in Brain, and Providing Neuroprotection in Alzheimer Disease via Neuronal Synthesis of Transthyretin Protein

Transthyretin (TTR), a carrier protein present in the liver and choroid plexus of the brain, has been shown to be responsible for binding thyroid hormone thyroxin (T4) and retinol in plasma and cerebrospinal fluid (CSF). TTR aids in sequestering of beta-amyloid peptides Aβ deposition, and protects the brain from trauma, ischemic stroke and Alzheimer disease (AD). Accordingly, hippocampal gene expression of TTR plays a significant role in learning and memory as well as in simulation of spatial memory tasks. TTR via interacting with transcription factor CREB regulates this process and decreased expression leads to memory deficits. By different signaling pathways, like MAPK, AKT, and ERK via Src, TTR provides tropical support through megalin receptor by promoting neurite outgrowth and protecting the neurons from traumatic brain injury. TTR is also responsible for the transient rise in intracellular Ca2+ via NMDA receptor, playing a dominant role under excitotoxic conditions. In this review, we tried to shed light on how TTR is involved in maintaining normal cognitive processes, its role in learning and memory, under memory deficit conditions;by which mechanisms it promotes neurite outgrowth;and how it protects the brain from Alzheimer disease (AD).

Cross-Talk between Extracellular S1P/S1P2 and P42/44 MAPK in bcr/abl Positive Chronic Myeloid Leukemia Cells

Objective： BCR/ABL oncoprotein-expression is associated with uncontrolled cell growth. Sphingosine kinase 1 （SPK1） regulates the production of sphingosine 1-phosphate （S1P）, a key lipid signal molecular in cell proliferation and survival. The objective of this study was to elucidate the roles of S1P and its receptors in bcr/abl positive chronic myeloid leukemia （CML） cells. Methods： The expressions of SIP receptors： S1P1, S1P2 and S1P3 in CML cells were detected by RT-PCR. SPK1 expression, activity and extracellular S1P were determined in ECV304 and HL-60 cells which were transfected with bcr/abl gene. To elucidate the relationship between the BCR/ABL, ERK/MAPK （extracellular signal-regulated kinase/mitogen-activated protein kinase）, SPK/S 1P and S 1P/S 1 P2 signal pathways, bcr/abl positive CML cell line K562 was treated with STI571, PD98059, N,N-dimethyl sphingosine （DMS） and JTE-013. Results： Retrovirus-mediated overexpression of bcr/abl gene in ECV304 and HL-60 cells resulted in upregulation of the expression, activity of SPK1 and increase of the secretion of SIP, whereas treatment of STI571 and PD98059 decreased the BCR/ABL-induced S1P secretion. Treatment of DMS reduced S1P secretion and P42/44MAPK phosphorylation. S1P2-selective antagonist JTE-013 could also decrease P42/44MAPK phosphorylation. Conclusion： These results suggest that BCR/ABL up-regulates extracellular sphingosine 1-phosphate through sphingosine kinase 1 and there is cross-talk between SPK1/S1P/S1P2 and P42/44MAPK in bcr/abl positive CML cells.

Bromocriptine protects perilesional spinal cord neurons from lipotoxicity after spinal cord injury

Recent studies have revealed that lipid droplets accumulate in neurons after brain injury and evoke lipotoxicity,damaging the neurons.However,how lipids are metabolized by spinal cord neurons after spinal cord injury remains unclear.Herein,we investigated lipid metabolism by spinal cord neurons after spinal cord injury and identified lipid-lowering compounds to treat spinal cord injury.We found that lipid droplets accumulated in perilesional spinal cord neurons after spinal cord injury in mice.Lipid droplet accumulation could be induced by myelin debris in HT22 cells.Myelin debris degradation by phospholipase led to massive free fatty acid production,which increased lipid droplet synthesis,β-oxidation,and oxidative phosphorylation.Excessive oxidative phosphorylation increased reactive oxygen species generation,which led to increased lipid peroxidation and HT22 cell apoptosis.Bromocriptine was identified as a lipid-lowering compound that inhibited phosphorylation of cytosolic phospholipase A2 by reducing the phosphorylation of extracellular signal-regulated kinases 1/2 in the mitogen-activated protein kinase pathway,thereby inhibiting myelin debris degradation by cytosolic phospholipase A2 and alleviating lipid droplet accumulation in myelin debris-treated HT22 cells.Motor function,lipid droplet accumulation in spinal cord neurons and neuronal survival were all improved in bromocriptine-treated mice after spinal cord injury.The results suggest that bromocriptine can protect neurons from lipotoxic damage after spinal cord injury via the extracellular signal-regulated kinases 1/2-cytosolic phospholipase A2 pathway.

NOX4 promotes tumor progression through the MAPK-MEK1/2-ERK1/2 axis in colorectal cancer

BACKGROUND Metabolic reprogramming plays a key role in cancer progression and clinical outcomes;however,the patterns and primary regulators of metabolic reprogramming in colorectal cancer(CRC)are not well understood.AIM To explore the role of nicotinamide adenine dinucleotide phosphate oxidase 4(NOX4)in promoting progression of CRC.METHODS We evaluated the expression and function of dysregulated and survival-related metabolic genes using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes.Consensus clustering was used to cluster CRC based on dysregulated metabolic genes.A prediction model was constructed based on survival-related metabolic genes.Sphere formation,migration,invasion,proliferation,apoptosis and clone formation was used to evaluate the biological function of NOX4 in CRC.mRNA sequencing was utilized to explore the alterations of gene expression NOX4 over-expression tumor cells.In vivo subcutaneous and lung metastasis mouse tumor model was used to explore the effect of NOX4 on tumor growth.RESULTS We comprehensively analyzed 3341 metabolic genes in CRC and identified three clusters based on dysregulated metabolic genes.Among these genes,NOX4 was highly expressed in tumor tissues and correlated with worse survival.In vitro,NOX4 overexpression induced clone formation,migration,invasion,and stemness in CRC cells.Furthermore,RNA-sequencing analysis revealed that NOX4 overexpression activated the mitogen-activated protein kinase-MEK1/2-ERK1/2 signaling pathway.Trametinib,a MEK1/2 inhibitor,abolished the NOX4-mediated tumor progression.In vivo,NOX4 overexpression promoted subcutaneous tumor growth and lung metastasis,whereas trametinib treatment can reversed the metastasis.CONCLUSION Our study comprehensively analyzed metabolic gene expression and highlighted the importance of NOX4 in promoting CRC metastasis,suggesting that trametinib could be a potential therapeutic drugs of CRC clinical therapy targeting NOX4.

MEK抑制剂U0126对大鼠睾丸移植缺血再灌注损伤的保护作用

目的:探讨大鼠睾丸移植缺血再灌注损伤与细胞外信号调节激酶(ERK)表达的关系,以及MEK抑制剂(U0126)对移植睾丸的保护作用。方法:应用潭付清技术建立大鼠原位异体睾丸移植模型,将实验动物分为7组:1正常对照组;2冷灌注对照组;3假手术对照组;和应用潭付清技术建立大鼠原位异体睾丸移植模型的4睾丸移植1组(移植后30min取材);5睾丸移植2组(移植后1周取材);6U0126预处理1组(U0126预处理并在移植30min后取材);7U0126预处理2组(U0126预处理并在移植1周后取材)。Western blot法测定移植睾丸ERK1、ERK2、pERK1及pERK2的表达水平,光镜和电镜下观察组织学改变,并应用放免法测定移植受体血清T、FSH、LH值。结果:各对照组间的ERK表达、组织学改变及生殖激素水平均无显著差异(P>0.05);睾丸移植1组ERK1、ERK2、pERK1及pERK2表达水平明显高于正常对照组(P<0.05);U0126预处理1组ERK1和ERK2水平较睾丸移植1组无显著差异(P>0.05),而pERK1和pERK2水平显著低于睾丸移植1组(P<0.05);U0126预处理1组的组织学改变与正常对照组类似,但明显轻于睾丸移植1组;U0126预处理2组组织学损伤轻于睾丸移植2组,生殖激素水平与正常对照组无明显差异(P>0.05),但明显高于睾丸移植2组(P<0.01)。结论:大鼠睾丸移植后植睾ERK1、ERK2、pERK1及pERK2的表达水平明显升高,导致移植睾丸组织结构损伤和生殖激素分泌功能减退;U0126可通过抑制ERK1和ERK2磷酸化,减轻移植睾丸的早期出现的缺血再灌注损伤,短期内保护其生精功能,并维持其生殖激素水平。

TRAIL-induced apoptosis of hepatocellular carcinoma cells is augmented by targeted therapies

AIM:To analyze the effect of chemotherapeutic drugs and specific kinase inhibitors,in combination with the death receptor ligand tumor necrosis factor-related apoptosis inducing ligand(TRAIL),on overcoming TRAIL resistance in hepatocellular carcinoma(HCC)and to study the efficacy of agonistic TRAIL antibodies,as well as the commitment of antiapoptotic BCL-2 proteins, in TRAIL-induced apoptosis. METHODS:Surface expression of TRAIL receptors (TRAIL-R1-4)and expression levels of the antiapoptotic BCL-2 proteins MCL-1 and BCL-xL were analyzed by flow cytometry and Western blotting,respectively. Knock-down of MCL-1 and BCL-xL was performed by transfecting specific small interfering RNAs.HCC cellswere treated with kinase inhibitors and chemotherapeutic drugs.Apoptosis induction and cell viability were analyzed via flow cytometry and 3-(4,5-Dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. RESULTS:TRAIL-R1 and-R2 were profoundly expressed on the HCC cell lines Huh7 and Hep-G2. However,treatment of Huh7 and Hep-G2 with TRAIL and agonistic antibodies only induced minor apoptosis rates.Apoptosis resistance towards TRAIL could be considerably reduced by adding the chemotherapeutic drugs 5-fluorouracil and doxorubicin as well as the kinase inhibitors LY294002[inhibition of phosphoinositol- 3-kinase(PI3K)],AG1478(epidermal growth factor receptor kinase),PD98059(MEK1),rapamycin(mam- malian target of rapamycin)and the multi-kinase inhibitor Sorafenib.Furthermore,the antiapoptotic BCL-2 proteins MCL-1 and BCL-xL play a major role in TRAIL resistance:knock-down by RNA interference increased TRAIL-induced apoptosis of HCC cells.Additionally, knock-down of MCL-1 and BCL-xL led to a significant sensitization of HCC cells towards inhibition of both c-Jun N-terminal kinase and PI3K.CONCLUSION:Our data identify the blockage of survival kinases,combination with chemotherapeutic drugs and targeting of antiapoptotic BCL-2 proteins as promising ways to overcome TRAIL resistance in HCC.

Cyclooxygenase-2 inhibitor inhibits hippocampal synaptic reorganization in pilocarpine-induced status epilepticus rats

Objective： To examine modulations caused by cyclooxygenase-2 （COX-2） inhibitors on altered microenvironments and overbalanced neurotransmitters in pilocarpine-induced epileptic status rats and to investigate possible mechanisms. Methods： Celecoxib （a COX-2 inhibitor） was administered 45 min prior to pilocarpine administration. The effects of COX-2 inhibitors on mlPSCs （miniature GABAergic inhibitory postsynaptic currents） of CA3 pyramidal cells in the hippocampus were recorded. Expressions of COX-2, c-Fos, newly generated neurons, and activated microgliosis were analyzed by immunohistochemistry, and expressions of c^-subunit of y-amino butyric acid （GABAA） receptors and mitogen-activated protein kinase/extracellular signal-regulated protein kinase （MAPK/ERK） activity were detected by Western blotting. Results： Pretreatment with celecoxib showed protection against pilocarpine-induced seizures. Celecoxib prevented microglia activation in the hilus and inhibited the abnormal neurogenesis and astrogliosis in the hippocampus by inhibiting MAPK/ERK activity and c-Fos transcription. Celecoxib also up-regulated the expression of GABAA receptors. NS-398 （N-2-cyclohexyloxy-4-nitrophenyl-methanesulfonamide）, another COX-2 inhibitor, enhanced the frequency and decay time of mIPSCs. Conclusion： The COX-2 inhibitor celecoxib decreased neuronal excitability and prevented epileptogenesis in pilocarpine-induced status epilepticus rats. Celecoxib regulates synaptic reorganization by inhibiting astrogliosis and ectopic neurogenesis by attenuating MAPK/ERK signal activity, mediated by a GABAergic mechanism.

Regulation of enolase activation to promote neural protection and regeneration in spinal cord injury

Spinal cord injury(SCI)is a debilitating condition characterized by damage to the spinal cord resulting in loss of function,mobility,and sensation with no U.S.Food and Drug Administration-approved cure.Enolase,a multifunctional glycolytic enzyme upregulated after SCI,promotes pro-and anti-inflammatory events and regulates functional recovery in SCI.Enolase is normally expressed in the cytosol,but the expression is upregulated at the cell surface following cellular injury,promoting glial cell activation and signal transduction pathway activation.SCI-induced microglia activation triggers pro-inflammatory mediators at the injury site,activating other immune cells and metabolic events,i.e.,Rho-associated kinase,contributing to the neuroinflammation found in SCI.Enolase surface expression also activates cathepsin X,resulting in cleavage of the C-terminal end of neuron-specific enolase(NSE)and non-neuronal enolase(NNE).Fully functional enolase is necessary as NSE/NNE C-terminal proteins activate many neurotrophic processes,i.e.,the plasminogen activation system,phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B,and mitogen-activated protein kinase/extracellular signal-regulated kinase.Studies here suggest an enolase inhibitor,ENOblock,attenuates the activation of Rho-associated kinase,which may decrease glial cell activation and promote functional recovery following SCI.Also,ENOblock inhibits cathepsin X,which may help prevent the cleavage of the neurotrophic C-terminal protein allowing full plasminogen activation and phosphatidylinositol-4,5-bisphosphate 3-kinase/mitogen-activated protein kinase activity.The combined NSE/cathepsin X inhibition may serve as a potential therapeutic strategy for preventing neuroinflammation/degeneration and promoting neural cell regeneration and recovery following SCI.The role of cell membrane-expressed enolase and associated metabolic events should be investigated to determine if the same strategies can be applied to other neurodegenerative diseases.Hence,this review discusses the importance of enolase activation and inhibition as a potential therapeutic target following SCI to promote neuronal survival and regeneration.

Hepatitis C virus infection and insulin resistance

Approximately 170 million people worldwide are chronically infected with hepatitis C virus(HCV).Chronic HCV infection is the leading cause for the development of liver fibrosis,cirrhosis,hepatocellular carcinoma(HCC)and is the primary cause for liver transplantation in the western world.Insulin resistance is one of the pathological features in patients with HCV infection and often leads to development of typeⅡdiabetes.Insulin resistance plays an important role in the development of various complications associated with HCV infection.Recent evidence indicates that HCV associated insulin resistance may result in hepatic fibrosis,steatosis,HCC and resistance to anti-viral treatment.Thus,HCV associated insulin resistance is a therapeutic target at any stage of HCV infection.HCV modulates normal cellular gene expression and interferes with the insulin signaling pathway.Various mechanisms have been proposed in regard to HCV mediated insulin resistance,involving up regulation of inflammatory cytokines,like tumor necrosis factor-α,phosphorylation of insulin-receptor substrate-1,Akt,up-regulation of gluconeogenic genes like glucose 6 phosphatase,phosphoenolpyruvate carboxykinase 2,and accumulation of lipid droplets.In this review,we summarize the available information on how HCV infection interferes with insulin signaling pathways resulting in insulin resistance.

Role of ERK-MAPK signaling pathway in pentagastrin-regulated growth of large intestinal carcinoma

AIM: To explore the role and mechanisms of extracellular signal-regulated protein kinase-mitogen-activated protein kinase (ERK-MAPK) signaling in pentagastrin-regulated growth of large intestinal carcinoma.