MiRNA-145-5p inhibits gastric cancer progression via the serpin family E member 1-extracellular signal-regulated kinase-1/2 axis

BACKGROUND MicroRNAs(miRNAs)regulate gene expression and play a critical role in cancer physiology.However,there is still a limited understanding of the function and regulatory mechanism of miRNAs in gastric cancer(GC).AIM To investigate the role and molecular mechanism of miRNA-145-5p(miR145-5p)in the progression of GC.METHODS Real-time polymerase chain reaction(RT-PCR)was used to detect miRNA expression in human GC tissues and cells.The ability of cancer cells to migrate and invade was assessed using wound-healing and transwell assays,respectively.Cell proliferation was measured using cell counting kit-8 and colony formation assays,and apoptosis was evaluated using flow cytometry.Expression of the epithelial-mesenchymal transition(EMT)-associated protein was determined by Western blot.Targets of miR-145-5p were predicated using bioinformatics analysis and verified using a dual-luciferase reporter system.Serpin family E member 1(SERPINE1)expression in GC tissues and cells was evaluated using RT-PCR and immunohistochemical staining.The correlation between SERPINE1 expression and overall patient survival was determined using Kaplan-Meier plot analysis.The association between SERPINE1 and GC progression was also tested.A rescue experiment of SERPINE1 overexpression was conducted to verify the relationship between this protein and miR-145-5p.The mechanism by which miR-145-5p influences GC progression was further explored by assessing tumor formation in nude mice.RESULTS GC tissues and cells had reduced miR-145-5p expression and SERPINE1 was identified as a direct target of this miRNA.Overexpression of miR-145-5p was associated with decreased GC cell proliferation,invasion,migration,and EMT,and these effects were reversed by forcing SERPINE1 expression.Kaplan-Meier plot analysis revealed that patients with higher SERPINE1 expression had a shorter survival rate than those with lower SERPINE1 expression.Nude mouse tumorigenesis experiments confirmed that miR-145-5p targets SERPINE1 to regulate extracellular signal-regulated kinase-1/2(ERK1/2).CONCLUSION This study found that miR-145-5p inhibits tumor progression and is expressed in lower amounts in patients with GC.MiR-145-5p was found to affect GC cell proliferation,migration,and invasion by negatively regulating SERPINE1 levels and controlling the ERK1/2 pathway.

Dexamethasone suppresses DU145 cell proliferation and cell cycle through inhibition of the extracellular signal-regulated kinase 1 /2 pathway and cyclin D1 expression

Aim： To determine the mechanisms of glucocorticoids in inhibiting advanced prostate cancer growth. Methods： The cell proliferation and cell cycle of prostate cancer DU145 cells following dexamethasone treatment were determined by proliferation assay and fluorescence-activated cell sorter. Western blot analysis was carried out to evaluate the effects of dexamethasone on phosphorylation of extracellular signal-regulated kinase （ERK）1/2 and expression of cyclin D1 in DU145 cells with or without glucocorticoid receptor （GR） antagonist RU486. Reverse transcription- polymerase chain reaction verified the expression of GR mRNA in DU145 cells. Results： Dexamethasone significantly inhibited DU 145 cell proliferation at the G0/G1 phase. Westem blot analysis showed a dramatic reduction of ERK1/2 activity and cyclin D1 expression in dexamethasone-treated cells. The decreased phosphorylation of ERK1/2 in dexamethasone-treated cells was attenuated by GR blockade. Additionally, the effects of dexamethasone in inhibiting cyclin D1 expression were altered by GR blockade. Conclusion： Dexamethasone suppresses DU145 cell proliferation and cell cycle, and the underlying mechanisms are through the inhibition of phosphorylation of ERK1/2 and cyclin D1 expression. The inhibition of ERK1/2 phosphorylation and cyclin D1 expression is attenuated by GR blockade, suggesting that GR regulates ERK1/2 and cyclin D1 pathways. These observations suggest that dexamethasone has a potential clinical application in prostate cancer therapy.

Downregulation of Aquaporin 4 Expression through Extracellular Signal-regulated Kinases1/2 Activation in Cultured Astrocytes Following Scratch-injury

Objective To investigate the role of extracellular signal-regulated kinase1/2（ERK1/2） pathway in the regulation of aquaporin 4（AQP4） expression in cultured astrocytes after scratch-injury. Methods The scratch-injury model was produced in cultured astrocytes of rat by a 10-μL plastic pipette tip. The morphological changes of astrocytes and lactate dehydrogenase（LDH） leakages were observed to assess the degree of scratch-injury. AQP4 expression was detected by immunofluorescence staining and Western blot, and phosphorylated-ERK1/2（p-ERK1/2） expression was determined by Western blot. To explore the effect of ERK1/2 pathway on AQP4 expression in scratch-injured astrocytes, 10 μmol/L U0126（ERK1/2 inhibitor） was incubated in the medium at 30 min before the scratch-injury in some groups. Results Increases in LDH leakage were observed at 1, 12, and 24 h after scratch-injury, and AQP4 expression was reduced simultaneously. Decrease in AQP4 expression was associated with a significant increase in ERK1/2 activation. Furthermore, pretreatment with U0126 blocked both ERK1/2 activation and decrease in AQP4 expression induced by scratch-injury. Conclusion These results indicate that ERK1/2 pathway down-regulates AQP4 expression in scratch-injured astrocytes, and ERK1/2 pathway might be a novel therapeutic target in reversing the effects of astrocytes that contribute to traumatic brain edema.

Time-dependent effects of electroacupuncture at the Ren channel on extracellular signal-regulated kinases 1/2 expression in focal cerebral ischemia rats

BACKGROUND： The onset of focal cerebral ischemia activates extracellular signal-regulated kinases 1 and 2, regulates cell cycle, promotes cell proliferation and differentiation, and affects the normal stage and function of brain cells. OBJECTIVE： To observe the effects of electroacupuncture at the Ren channel on extracellular signal-regulated kinases 1/2 expression in the lateral cerebral ventricle wall of rats with focal cerebral ischemia. The effects were analyzed at different time points after intervention. DESIGN： Randomized controlled study. SETTING： Department of Anatomy, Sun Yat-Sen University. MATERIALS： A total of 60 healthy adult male Wistar rats weighing （250±10） g were provided by the Experimental Animal Center, Medical College of Sun Yat-Sen University. The animal experiment was conducted with confirmed consent by the local ethics committee. The GB6805-Ⅱ electric acupuncture apparatus was provided by Shanghai Medical Equipment High-techno Company. METHODS： The experiment was performed at the Laboratory of Anatomy, Sun Yat-Sen University, from February to July 2007. All experimental animals were randomly divided into the following groups： normal group （n = 6）, sham operation group （n = 18）, model group （n = 18）, and electroacupuncture group （n = 18）. Middle cerebral artery occlusion （MCAO） was performed in the model group and electroacupuncture group. Zea Longa＇s grading standard was used to assess neurological impairment after reperfusion; animals whose grades were between l and 4 were included in this study. The normal control group was not exposed to MCAO. In sham operation animals, the right common carotid artery （CCA） was isolated, and the external carotid artery （ECA） was damaged, but no embolism was induced. The electroacupuncture group was given acupuncture on the second day after surgery. The acupoint locations were chosen according to Experimental Acupuncture （People＇s Publishing House; 1997; First Edition）. The Chengjiang, Qihai, and Guanyuan acupoints were labeled and connected to a G6805 electroacupuncture apparatus with sparse-dense waves （sparse waves were 30 Hz, dense waves were 100 Hz）, with a frequency of 6-15 V. The duration was 20 minutes. Two days after surgery, the model and sham operation groups were placed with their backs on the operating table, but they received no acupuncture. However, the normal group received acupuncture. The experimental animals under anesthesia were sacrificed on days 7, 14, and 28 post-surgery. Western blot analysis was used to measure expression of extracellular signal-regulated kinases 1/2 in the inferior region of the lateral cerebral ventricle wall. Expression was measured in the normal group at time points corresponding to the sham operation group. MAIN OUTCOME MEASURES： Expression of extracellular signal-regulated kinases 1/2 in the inferior region of the lateral cerebral ventricle wall at different time points after intervention. RESULTS： All 60 rats were included in the final analysis, without any loss. Seven days after MCAO, there was no significant difference in extracellular signal-regulated kinases 1/2 expression in the electroacupuncture group compared to the model group （P 〉 0.05）. However, extracellular signal-regulated kinases 1/2 expression significantly increased in the model group at 14 and 28 days after treatment （P 〈 0.05）. CONCLUSION： Electroacupuncture at the Ren channel can enhance extracellular signal-regulated kinasesl/2 expression in the inferior region of the lateral cerebral ventricle wall of rats with focal cerebral ischemia. However, this effect is not apparent until 14 days after electroacupuncture intervention.

Activation of extracellular signal-related kinases 1 and 2 in Sertoli cells in experimentally cryptorchid rhesus monkeys

Aim： To assess the spatiotemporal changes in the expression of extracellular signal-regulated kinases 1 and 2 （ERK1/ 2）, c-Jun N-terminal kinases （JNK） and p38 mitogen-activated protein kinases （MAPK） in response to heat stress in the cryptorchid testis, and to investigate a possible relation to Sertoli cell dedifferentiation. Methods： Immunohistochemistry and western blot were used to examine the expression and activation of ERK1/2, p38 and JNK in the cryptorchid testis at various stages after experimental cryptorchidism. Results： The abdominal temperature did not obviously change the total ERK1/2 expression but significantly activated phospho-ERK1/2 in the Sertoli cells of the cryptorchid testis. Heat stress increased total JNK expression in the Sertoli cells of the cryptorchid testis but did not activate phospho-JNK. Neither total p38 nor phospho-p38 was induced by heat stress in the Sertoli cells of the cryptorchid testis. Changes in the spatiotemporal expression of cytokeratin 18 （CK18）, a marker of immature or undifferentiated Sertoli cells, were induced in the cryptorchid testis in a pattern similar to the activation of ERK1/2. Condusion： The activation of ERK1/2 in the testis may be related to dedifferentiation of Sertoli cells under heat stress induced by experimental cryptorchidism.

Activation of extracellular signal-related kinases 1 and 2 in Sertoli cells in experimentally cryptorchid rhesus monkeys

Aim:To assess the spatiotemporal changes in the expression of extracellular signal-regulated kinases 1 and 2(ERK1/ 2),c-Jun N-terminal kinases(JNK)and p38 mitogen-activated protein kinases(MAPK)in response to heat stress in the cryptorchid testis,and to investigate a possible relation to Sertoli cell dedifferentiation.Methods:Immunohis- tochemistry and western blot were used to examine the expression and activation of ERK1/2,p38 and JNK in the cryptorchid testis at various stages after experimental cryptorchidism.Results:The abdominal temperature did not obviously change the total ERK1/2 expression but significantly activated phospho-ERK1/2 in the Sertoli cells of the cryptorchid testis.Heat stress increased total JNK expression in the Sertoli cells of the cryptorchid testis but did not activate phospho-JNK.Neither total p38 nor phospho-p38 was induced by heat stress in the Sertoli cells of the cryptorchid testis.Changes in the spatiotemporal expression of cytokeratin 18(CK18),a marker of immature or undifferentiated Sertoli cells,were induced in the cryptorchid testis in a pattern similar to the activation of ERK1/2. Conclusion:The activation of ERK1/2 in the testis may be related to dedifferentiation of Sertoli cells under heat stress induced by experimental cryptorchidism.

艾灸对脾虚胃溃疡模型大鼠血清TFF及胃黏膜ERK1/2、PCNA的影响

目的观察艾灸对脾虚胃溃疡模型大鼠血清三叶因子(TFF1、TFF2)、胃黏膜细胞外信号调节激酶1/2(ERK1/2)和增殖细胞抗原(PCNA)的影响,探讨艾灸促进胃黏膜增殖修复的可能机制。方法将50只健康SD大鼠随机抽取10只为空白组,其余40只采用苦寒泻下法+无水乙醇灌胃建立脾虚胃溃疡大鼠模型,模型成立后随机分为模型组、四君子汤组、艾灸组和艾灸非穴位组,每组10只。各组予以相应处理,8 d后采用酶联免疫吸附法检测血清中TFF1、TFF2的含量,免疫印迹法检测胃黏膜组织p-ERK1/2蛋白的表达,免疫组化法测胃黏膜细胞PCNA的表达。结果艾灸足三里、中脘等穴能明显提高胃黏膜损伤大鼠血清TFF1、TFF2的含量,增强胃黏膜损伤大鼠胃黏膜组织p-ERK1/2蛋白和PCNA的表达(P<0.05或P<0.01)。结论艾灸能促进脾虚胃溃疡大鼠损伤胃黏膜的增殖修复,其可能的机制是通过提高TFF1、TFF2的含量,激活TFF/ERK信号转导通路,增强PCNA的表达有关。

细胞外信号调节激酶1/2传导通路在不同发育阶段皮肤组织内的变化

为研究磷酸化细胞外信号调节激酶1/2（p-ERK1/2）、Ras和C-fos在不同发育阶段皮肤中的表达特征及其可能的生物学意义,用免疫组化技术检测这3种蛋白在8例胎儿皮肤和8例成人皮肤中的表达变化规律。结果发现,在胎儿发育初期,p-ERK1/2、Ras和C-fos蛋白表达较低,随着胎儿生长发育,这3种蛋白的阳性细胞率逐渐增大,在妊娠后期胎儿和成人皮肤组织中,3种蛋白的阳性细胞率明显高于妊娠早期胎儿皮肤（P<0.01）。p-ERK1/2、Ras和C-fos蛋白在不同发育阶段皮肤组织内都有表达,显示它们可能对皮肤的发生、结构和功能的维持以及损伤后修复十分重要。

去卵巢大鼠海马CA1／CA2区ERK1／2的基础活性和诱导活性降低

目的:观察去卵巢大鼠空间学习记忆能力的变化与海马中胞外信号调节激酶1/2(ERK1/2)通路的关系。方法:雌性SD大鼠随机分为假手术组和去卵巢组,饲养4个月后采用Morris水迷宫测试空间学习记忆能力,于测试前将各组组内又分为训练组和非训练组,训练组用于测定经学习记忆训练诱发的ERK1/2的诱导活性,非训练组用于测定未经学习记忆训练时的ERK1/2的基础活性,Western blot方法检测海马CA1/CA2区p-ERK1/2蛋白及Raf激酶抑制蛋白(RKIP)的变化。结果:①与假手术组比较,去卵巢组大鼠的空间学习记忆能力明显下降(P<0.05)。②各组中的训练大鼠p-ERK1/2蛋白水平明显高于非训练大鼠(P<0.05)。③去卵巢组训练及非训练大鼠的p-ERK1/2蛋白水平均相应低于假手术组训练及非训练大鼠(P<0.05)。④去卵巢组RKIP蛋白表达水平明显高于假手术组(P<0.05)。结论:雌激素缺乏大鼠的空间学习记忆能力下降与海马CA1/CA2区ERK1/2通路的基础和诱导活性降低以及该通路的抑制蛋白RKIP的表达增加有关。

胰岛素样生长因子-1通过细胞外信号调节激酶1/2通路下调转录因子基本转录元件结合蛋白表达抗心肌细胞凋亡

目的探讨胰岛素样生长因子-1(IGF-1)对大鼠心肌细胞凋亡保护作用的基因调控机制。方法体外培养新生大鼠心肌细胞,10nmol/L IGF-1刺激的同时,分别加入磷脂酰肌醇-3激酶(PI3K)、细胞外信号调节激酶(ERK)1/2和Raf-1 3条通路抑制剂(20μmol/L),通过RT-PCR及Western blotting方法观察IGF-1调节基本转录元件结合蛋白(BTEB)的基因表达及其通路调控。100μmol/L H2O2处理诱导心肌细胞凋亡,通过DNA梯度分析、Annexin V-FITC/PI双染色法、Caspase-3活性测定、Hoechest33258染色法观察用BTEB特异性siRNA人为下调BTEB基因表达后对心肌细胞凋亡的影响。结果大鼠心肌细胞经IGF-1刺激60min后,BTEB mRNA和蛋白表达均明显下降;与对照组相比,加入ERK1/2通路抑制剂PD98059组BTEB的mRNA和蛋白表达均明显增高(P<0.01);H2O2诱导的大鼠心肌细胞于下调BTEB表达后,DNA片段化改善,心肌细胞凋亡率下降(P<0.05),Caspase-3活性降低(P<0.05),凋亡小体减少,与IGF-1的抗心肌细胞凋亡效果相似。结论 IGF-1可以通过ERK1/2通路下调转录因子BTEB基因表达而发挥抗心肌细胞凋亡的作用。

细胞外信号调节激酶1/2信号通路在小鼠T细胞增殖、周期和活化中的作用

目的:探讨细胞外信号调节激酶1/2(ERK1/2)信号通路在小鼠T淋巴细胞增殖、周期和活化中的作用。方法:分离小鼠淋巴结细胞,藉多克隆刺激剂刀豆蛋白(ConA)或佛波醇酯(PDB)加离子霉素(Ion)刺激,流式细胞术分析ERK1/2信号通路的特异性阻断剂PD98059对小鼠T淋巴细胞增殖、周期和活化的影响。结果:活体染料羧基荧光素乙酰乙酸染色分析显示,不同浓度(5、10、20、30、40μmol/L)的PD98059对ConA诱导的T淋巴细胞增殖具有明显的抑制作用,呈现剂量依赖关系(r=0.985,P<0.01)。碘化丙锭染色分析表明,PD98059可阻止ConA刺激的T淋巴细胞进入S期和G2/M期,PD98059对PDB+Ion刺激的T淋巴细胞细胞周期的影响与ConA刺激相似,不同的是S期和G2/M期的变化较ConA作用更显著。荧光标记单克隆抗体染色显示,不同浓度的PD98059仅能轻微影响T淋巴细胞表面活化标志CD69和CD25的表达。结论:PD98059对小鼠T淋巴细胞的增殖有明显抑制作用,并阻止其进入S期和G2/M期,但不能明显抑制小鼠T淋巴细胞的早期和中期活化。

Regulating effect of glycyrrhetinic acid on bronchial asthma smooth muscle proliferation and apoptosis as well as inflammatory factor expression through ERK1/2 signaling pathway

Objective: To study the influence of glycyrrhetinic acid(GA) on bronchial asthma(BA)smooth muscle proliferation and apoptosis as well as inflammatory factor expression and its molecular mechanism.Methods: Male SD guinea pigs were selected and made into asthma models, bronchial asthma smooth muscle cells were cultured and divided into BA group, GA group and GA + LM group that were treated with serum-free RPMI1640 culture medium, serumfree RPMI1640 culture medium containing 50 ng/mL glycyrrhetinic acid, serum-free RPMI1640 culture medium containing 50 ng/mL glycyrrhetinic acid and 100 ng/mL LM22B-10 respectively; normal guinea pigs were collected and bronchial smooth muscle cells were cultured as control group. The cell proliferation activity as well as the expression of proliferation and apoptosis genes, inflammatory factors and p-ERK1/2 was determined.Results: Proliferation activity value and m RNA expression of Bcl-2, TNF-α, IL-4, IL-6,YKL-40, protein expression of p-ERK1/2 of airway smooth muscle cell in BA group were significantly higher than those of control group while m RNA expression levels of Bax,caspase-9 as well as caspase-3 were significantly lower than that of control group(P < 0.05); proliferation activity value and m RNA expression of Bcl-2, TNF-α, IL-4, IL-6, YKL-40, protein expression of p-ERK1/2 of airway smooth muscle cell in GA group were significantly lower than those of BA group(P < 0.05) while the m RNA expression levels of Bax, caspase-9 as well as caspase-3 were significantly higher than those of BA group(P < 0.05); proliferation activity value and m RNA expression of Bcl-2, TNF-α, IL-4, IL-6, YKL-40 of airway smooth muscle cell in GA + LM group were significantly higher than those of GA group(P < 0.05) while m RNA expression levels of Bax, caspase-9 as well as caspase-3 were significantly lower that of GA group(P < 0.05).Conclusion: GA can inhibit the proliferation of bronchial smooth muscle cells and reduce the expression of inflammatory factors by inhibiting the phosphorylation of ERK1/2.

Differential expression of Bcl-2 and Bax during gastric ischemia-reperfusion of rats

AIM: To investigate expression of Bcl-2 and Bax in gastric ischemia-reperfusion (GI-R) and involvement of extracellular signal-regulated kinase (ERK) 1/2 activation. METHODS: The GI-R model was established by ligature of the celiac artery for 30 min and reperfusion in SpragueDawley rats. Rats were assigned to groups in accordance with their evaluation period: control, 0, 0.5, 1, 3, 6, 24, 48, and 72 h. Expression and distribution of Bcl-2 and Bax proteins were analyzed by immunohistochemistry and western blotting in gastric tissue samples after sacrifice. RESULTS: Compared with controls, the percentage of positive cells and protein levels of Bcl-2 decreased inthe early phases of reperfusion, reached its minimum at 1 h (P < 0.05); it then increased, reaching its peak at 24 h of reperfusion (P < 0.05). The pattern of Bax expression was opposite to that of Bcl-2. Bax expression increased after reperfusion, with its peak at 1 h of reperfusion (P < 0.05), and then it decreased gradually to a minimum at 24 h after reperfusion (P < 0.05). On the other hand, inhibition of activation of ERK1/2 induced by PD98059, a specific upstream MEK inhibitor, had significant effects on Bcl-2 and Bax in GI-R. Compared with GI-R treatment only at 3 h of reperfusion, PD98059 reduced the number of Bcl-2 positive cells (0.58% of R3h group, P < 0.05) and Bcl-2 protein level (74% of R3h group, P < 0.05) but increased the number of Bax-positive cells (1.33-fold vs R3h group, P < 0.05) and Bax protein level (1.35-fold of R3h group, P < 0.05). CONCLUSION: These results indicated that the Bcl-2 and Bax played a pivotal role in the gastric mucosal I-R injury and repair by activation of ERK1/2.

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.

Role of extracellular signal-regulated kinase 1/2 in cigarette smoke-induced mucus hypersecretion in a rat model

Background Airway mucus hypersecretion is an important pathophysiological feature of chronic obstructive pulmonary disease, which is closely associated with cigarette smoking. However, the signal transduction pathway from the cell surface to the nucleus through which cigarette smoke causes upregulation of mucin gene expression is not well known. This study was designed to investigate the role of extracellular signal-regulated Kinase 1/2 （ERK 1/2） in airway mucus hypersecretion induced by cigarette smoke in rats. Methods A rat model of airway mucus hypersecretion was induced by exposure to cigarette smoke for 4 weeks. Rats exposed to inhalation of cigarette smoke or normal saline were given an intraperitoneal injection of U0126, a specific MEK1 kinase inhibitor, at doses of 0.25 mg/kg, 0.5 mg/kg and 1 mg/kg for 14 days. Expression of MUC5AC mRNA and protein, ERK 1/2 and phosphorylated-ERK 1/2 （p-ERK 1/2） were detected by RT-PCR, immunohistochemistry and Western blotting. Results Cigarette smoke significantly increased airway goblet cells metaplasia, induced the overexpression of MUC5AC mRNA and protein in bronchial epithelia, and increased the ratio of p-ERK 1/2 and ERK 1/2. U0126 significantly attentuated the expression of MUC5AC mRNA and protein induced by cigarette smoke （P 〈0.05）. Moreover, there was a significant positive correlation between the ratio of p-ERK1/2 to ERK1/2 and the expression of MUC5AC mRNA and protein （P 〈0.05）. Conclusions Inhibition of ERK 1/2 by U0126 decreased the ratio of p-ERK 1/2 to ERK 1/2 and expression of MUC5AC mRNA and protein. ERK 1/2 may play an essential role in cigarette smoke-induced mucus hypersecretion in vivo.

Glucocorticoid modulation of extracellular signal-regulated protein kinase 1/2 and p38 in human ovarian cancer HO-8910 cells

Objective To investigate the signaling pathway through testing the effects of dexamethasone (Dex) on the activation of the extracellular signal-regulated protein kinase 1/2 (ERK1/2) and p38 kinase (p38) in HO-8910 cells.Methods Activation of the ERK1/2 and p38 was detected by Western blotting using the antibodies against the total ERK1/2 and p38 mitogen-activated protein kinases (MAPKs) protein and the phosphorylated forms of them. Results Dex could suppress the activation of ERK1/2, while enhance the activation of p38 rapidly and strongly in a dose- and time- dependent manner. Neither effect could be blocked by RU486, the antagonist of glucocorticoid receptor (GR).Conclusion Dex has rapid effects on the activation of ERK1/2 and p38, and these effects are not mediated by GR.

Emodin regulating excision repair cross-complementation group 1 through fibroblast growth factor receptor 2 signaling

AIM: To investigate the molecular mechanisms underlying the reversal effect of emodin on platinum resistance in hepatocellular carcinoma. METHODS: After the addition of 10 μmol/L emodin to HepG2/oxaliplatin (OXA) cells, the inhibition rate (IR), 50% inhibitory concentration (IC 50 ) and reversal index (IC 50 in experimental group/IC 50 in control group) were calculated. For HepG2, HepG2/OXA, HepG2/OXA/T, each cell line was divided into a control group, OXA group, OXA + fibroblast growth factor 7 (FGF7) group and OXA + emodin group, and the final concentrations of FGF7, emodin and OXA in each group were 5 ng/mL, 10 μg/mL and 10 μmol/L, respectively. Single-cell gel electrophoresis was conducted to detect DNA damage, and the fibroblast growth factor receptor 2 (FGFR2), phosphorylated extracellular signal-regulated kinase 1/2 (p-ERK1/2) and excision repair cross-complementing gene 1 (ERCC1) protein expression levels in each group were examined by Western blotting. RESULTS: Compared with the IC50 of 120.78 μmol/L in HepG2/OXA cells, the IC 50 decreased to 39.65 μmol/L after treatment with 10 μmol/L emodin; thus, the reversal index was 3.05. Compared with the control group, the tail length and Olive tail length in the OXA group, OXA + FGF7 group and OXA + emodin group were significantly increased, and the differences were statistically significant (P < 0.01). The tail length and Olive tail length were lower in the OXA + FGF7 group than in the OXA group, and this difference was also statistically significant. Compared with the OXA + FGF7 group, the tail extent, the Olive tail moment and the percentage of tail DNA were significantly increased in the OXA + emodin group, and these differences were statistically significant (P < 0.01). In comparison with its parental cell line HepG2, the HepG2/OXA cells demonstrated significantly increased FGFR2, p-ERK1/2 and ERCC1 expression levels, whereas the expression of all three molecules was significantly inhibited in HepG2/ OXA/T cells, in which FGFR2 was silenced by FGFR2 shRNA. In the examined HepG2 cells, the FGFR2, p-ERK1/2 and ERCC1 expression levels demonstrated increasing trends in the OXA group and OXA + FGF7 group. Compared with the OXA group and OXA + FGF7 group, the FGFR2, p-ERK1/2, and ERCC1 expression levels were significantly lower in the OXA + emodin group, and these differences were statistically significant. In the HepG2/OXA/T cell line that was transfected with FGFR2 shRNA, the FGFR2, p-ERK1/2 and ERCC1 expression levels were significantly inhibited, but there were no significant differences in these expression levels among the OXA, OXA + FGF7 and OXA + emodin groups. CONCLUSION: Emodin markedly reversed OXA resistance by enhancing OXA DNA damage in HepG2/OXA cells, and the molecular mechanism was related to the inhibitory effect on ERCC1 expression being mediated by the FGFR2/ERK1/2 signaling pathway.

Differential activation of mitogen-activated protein kinases by γ-irradi-ation in IEC-6 cells: Role of intracellular Ca^(2+)

Objective: To explore the effects of γ-irradiation on mitogen-activated protein kinases (MAPKs) and role of intracellular calcium in this event in intestinal epithelial cell line 6 (IEC-6 cells). Methods: After cultured rat IIEC-6 cells with or without the pretreatment of intracellular Ca2+ chelator were exposed to Y-ir-radiation of 6 Gy, the total and phosphorylated MAPKs in the cells were determined with Western blotting and apoptosis was examined with flow cytometry. Activities of Extracellular signal-regulated protein kinase (ERK) and p38 MAPK were determined by using immuoprecipitation followed by Western blotting. Results: In response to γ-irradiation, phosphorylation of ERK was not significantly observed, while the levels of phosphorylated c-Jun NH2-terminal kinase (JNK) and p38 MAPK were increased in 30 min and reached the peak 2 h after exposure to 6 Gy γ-irradiation, though the cell viability was significantly lowered 12 h. On the other hand, no obvious changes were seen in the total protein levels of ERK, JNK and p38 MAPK. Chelation of intracellular Ca2+ almost completely suppressed the JNK and p38 MAPK phosphorylation induced by γ-irradia-tion, but removal of external Ca2+ had no such effect. Activation of p38 MAPK, but not of ERK, was seen to have a correlation with γ-irradiation induced apoptosis. Conclusion: The results suggest that γ-irradiation is a potent activator for JNK and p38 MAPK, and Ca2+ mobilized from intracellular stores plays an important role in the activation of MAPKs and the induction of apoptosis in IEC-6 cells.

Human ciliary muscle cell responses to kinins:Activation of ERK1/2 and pro-matrix metalloproteinases secretion

AIM To study activation of extracellular signal-regulated kinase-1/2(ERK1/2) and pro-matrix metalloproteinases(pro-MMPs) secretion from isolated primary human ciliary muscle(h-CM) cells in response to bradykinin(BK) and other agonists. METHODS Serum-starved h-CM cells were challenged with vehicle, BK agonists or antagonists. Cell lysates were evaluated for phosphorylated ERK1/2 using homogeneous timeresolved fluorescence technology based on a sandwich immunoassay. Rabbit polyclonal anti-pro-MMP antibodies were used to measure pro-MMPs using immunoblot analysis.RESULTS A 10 min incubation time using 5 × 104 h-CM cells/well was optimum condition for studying stimulation of ERK1/2 phosphorylation. BK(100 nmol/L) caused a 1.86 ± 0.26 fold(n = 3) increase in ERK1/2 phosphorylation above baseline. BK analogs, Met-Lys-BK and RMP-7(100 nmol/L), also stimulated ERK1/2 phosphorylation by 1.57 ± 0.04 and 1.55 ± 0.09 fold, respectively. However, DesArg9-Bradykinin, a B1 receptor-selective agonist(0.1-1 μmol/L), was essentially inactive. HOE-140 or WIN-64338(B2-antagonists) appreciably blocked phosphorylation of ERK1/2 induced by various BK agonists. Pre-treatmentof cells with a prostaglandin(PG) synthase inhibitor(bromfenac; 1 μmol/L) failed to alter kinin-induced ERK1/2 activation. BK and a non-peptide BK agonist(FR-190997)(10 nmol/L-1 μmol/L) also enhanced pro-MMPs secretion(pro-MMP-1 > pro-MMP-3 > pro-MMP-2; 1.45-1.75-fold over baseline) from h-CM cells. CONCLUSION These collective data suggest that B2 kinin receptors initiate signaling in h-CM cells by a relatively rapid mechanism(within minutes) involving ERK1/2 activation which in turn regulates MMPs production(within hours). The latter process does not involve PGs.

Bim和细胞外调节蛋白在肝癌多药耐药细胞中的表达

目的检测人肝癌耐药细胞Hep G-2/ADM和亲本细胞Hep G-2中ERK1,ERK2、ERK5和Bim的表达,探讨其对肝癌细胞多药耐药的影响。方法小剂量缓慢诱导法诱导建立人肝癌耐药细胞株Hep G-2/ADM;CCK-8法测定Hep G-2/ADM对多种化疗药物的交叉耐药性;Western-blotting检测MRP-1,P-gp,ERK1,ERK2,ERK5和Bim蛋白水平的表达;荧光定量PCR检测Bim mRNA的表达。结果化疗药物能够体外诱导肿瘤细胞产生耐药性,Hep G-2/ADM对ADM、5-FU和CDDP的耐药指数分别为6.8,4.1和4.5,且高表达MRP-1和P-gp蛋白;与亲本细胞Hep G-2相比,Hep G-2/ADM中ERK1,ERK2和ERK5的表达均升高,ERK1蛋白磷酸化水平无显著变化,ERK2磷酸化水平下降,且p-ERK1/2与ERK1/2的比值下降;Bim的mRNA和蛋白表达均下降。结论细胞外调节蛋白激酶ERKs和Bcl-2家族的促凋亡蛋白Bim的表达与人肝癌多药耐药的发生密切相关。