扇贝多肽经由EGFR-CDK-4通路抑制UVA诱导的HaCaT细胞凋亡

目的建立8J.cm-2紫外线A(UVA)辐射损伤永生化的人角质形成细胞株(HaCaT)细胞的病理模型,经由信号通路的表皮生长因子受体(EGFR),磷脂酰肌醇-3激酶(AKT),细胞周期蛋白(CyclinD1)至周期蛋白依赖激酶4(CDK-4)角度研究扇贝多肽(Polypeptide from Chlamys farreri,PCF)抑制UVA诱导HaCaT细胞凋亡的分子机制。方法采用琼脂糖凝胶电泳检测细胞凋亡;RT-PCR和DNA测序法检测胞内表皮生长因子受体EGFR的mRNA表达及基因变化;蛋白印迹法检测AKT,p-AKT,CyclinD1及CDK-4的蛋白表达水平。结果EGFR抑制剂AG1478和AKT抑制剂PHZ1023均可阻断UVA引起的细胞凋亡;1.42～5.68mmol.L-1范围内的PCF可抑制UVA辐射后细胞内EGFR的表达量。预先加入AG1478和PHZ1023则分别抑制UVA引起的AKT及CyclinD1,CDK-4蛋白水平的表达。结论PCF可以通过阻断EGFR-CDK-4通路来抑制UVA诱导的HaCaT细胞凋亡。     

三七总皂苷对人胃癌细胞株MKN-28增殖和凋亡的影响

目的观察三七总皂苷(Total Saponins of Panax notoginseng,TSPN)对人胃癌细胞株MKN-28增殖和凋亡的影响,探讨其诱导细胞凋亡是否涉及上调死亡受体5(DR5)的表达。方法体外培养人胃癌细胞株MKN-28,平皿克隆形成法测定细胞锚定依赖性生长能力,PI染色流式细胞术(Flow cytometry,FCM)分析细胞周期和凋亡率,Hoechst 33258染色荧光显微镜观察凋亡细胞的形态,Western Bloting检测分析药物对DR5蛋白表达的影响。结果平皿集落形成法检测显示TSPN对MKN-28细胞生长有抑制作用,且呈浓度依赖性。PI染色FCM结果表明TSPN以时间和浓度依赖性方式诱导MKN-28细胞凋亡,且使细胞周期阻滞于G1期。Hoechst 33258染色荧光显微镜观察可见核染色质凝集,凋亡细胞呈致密浓染,与对照组相比,TSPN处理后,凋亡细胞比例增加,且呈时间和浓度依赖性。Western Bloting检测显示TSPN诱导细胞凋亡的机制涉及上调死亡受体5的表达活性。结论 TSPN在体外对人胃癌MKN-28细胞具有抑制增殖和诱导凋亡的作用,初步推断TSPN诱发胃癌细胞凋亡与其上调死亡受体5的表达活性有关。     

抗肿瘤药Erlotinib

恶性肿瘤的特征是 ,细胞信号传导失调 ,导致细胞迅速增殖和 或凋亡抑制 ,进而引起癌细胞自发生长、入侵外围组织及转移。表皮生长因子受体 (EGFR)是一种 1型受体酪氨酸激酶 ,属信号蛋白 ,参与调节细胞分化 ,并在多种人类肿瘤(如肺癌、胰腺癌、卵巢癌、肾癌、胃癌、肝癌和乳腺癌     

黄酮类化合物对蛋白激酶的抑制作用

黄酮类化合物对丝裂原激活的蛋白激酶(MAPK)、细胞周期素依赖的蛋白激酶 (CDKs)、表皮生长因子受体 (EGFR)及Akt /蛋白激酶B活性均有较强的抑制作用 ,从而干预细胞信号转导 ,诱导细胞凋亡 ,抗肿瘤细胞增殖 ,促进抑癌基因表达和抑制癌基因表达。该类化合物抗肿瘤作用机制与它们能抑制各种细胞信号转导途径中的蛋白激酶有关 ,其有作为化学预防和化学治疗药物的潜在用途。     

蟛蜞菊内酯对人肾癌细胞的体外生长抑制作用

目的　探讨蟛蜞菊内酯对人肾癌细胞的生长抑制作用及相关机制。 方法　采用四甲基偶氮唑盐（MTT）法观察蟛蜞菊内酯对肾癌细胞活力的影响;通过流式细胞分析检测蟛蜞菊内酯对肾癌细胞凋亡和细胞周期的影响;通过免疫印迹法检测细胞凋亡和细胞周期相关蛋白的表达水平。 结果　蟛蜞菊内酯能够以剂量依赖的方式抑制肾癌细胞 ACHN 和 786-O 的生长;蟛蜞菊内酯能显著诱导肾癌细胞发生凋亡和 G0/G1 期阻滞。蟛蜞菊内酯能明显上调促凋亡蛋白 Bax 的表达,抑制抗凋亡蛋白 Bcl-2 和 Bcl-xL 的表达。此外,蟛蜞菊内酯还可抑制细胞周期相关蛋白 cyclin D1、CDK4 及 CDK6 的表达。 结论　蟛蜞菊内酯可诱导肾癌细胞凋亡并发生细胞周期阻滞,从而影响细胞活力,抑制其生长,可作为肾癌治疗的潜在药物。     

白藜芦醇体外诱导类风湿关节炎滑膜细胞凋亡的实验研究

目的探讨白藜芦醇(Res)体外对类风湿关节炎(RA)滑膜细胞的增殖抑制作用及其对细胞凋亡的影响。方法采用噻唑蓝(MTT)比色法检测Res对RA滑膜细胞的增殖抑制作用;采用流式细胞光度分析术(FCM)检测细胞凋亡率及细胞周期时相分布,同时进行细胞的形态学观察。结果MTT的检测结果显示药物浓度和细胞增殖抑制率间具有正相直线相关关系(P<0.01),Res体外作用类风湿关节炎滑膜细胞24 h对滑膜细胞的IC50为365μmol.L-1。FCM检测和细胞形态学观察结果显示Res可阻滞滑膜细胞于S期并诱导细胞凋亡,但细胞凋亡率并不完全与药物浓度成正相关。作用24 h时Res诱导类风湿关节炎滑膜细胞发生凋亡的最佳浓度是在200~400μmol.L-1。结论Res对类风湿关节炎滑膜细胞具有较强的增殖抑制作用,在一定药物浓度范围内,随药物浓度的增加Res可使细胞凋亡率升高,但超过一定作用浓度,药物的细胞毒作用增强,细胞凋亡率则成下降趋势。     

盐酸埃克替尼对人非小细胞肺癌HCC827细胞凋亡及EGFR下游信号通路蛋白表达的影响

目的 探讨盐酸埃克替尼(Icotinib)对人非小细胞肺癌(NSCLC)HCC827细胞凋亡及EGFR下游信号通路蛋白表达的影响.方法 通过噻唑蓝比色(MTT)法检测Icotinib对HCC827细胞增殖的影响,流式细胞仪观察Icotinib对HCC827细胞凋亡的诱导作用,采用蛋白质免疫印迹(Western blot)检测表皮生长因子受体(EGFR)、蛋白激酶B(AKT)、胞外信号调节激酶(ERK)、p-EGFR、p-AKT、p-ERK和Survivin等EGFR下游信号通路蛋白的表达水平.结果 Icotinib抑制HCC827细胞增殖和诱导细胞凋亡的作用具有浓度依赖性和时间依赖性(P<0.05);随着Icotinib对HCC827细胞作用的药物浓度升高,p-EGFR、p-AKT、p-ERK和survivin等EGFR下游信号通路蛋白的表达水平均明显下调(P<0.05).结论 Icotinib可能通过抑制EGFR下游信号通路蛋白的表达,进而有效抑制HCC827细胞的增殖和诱导HCC827细胞的凋亡.     

PARP-1抑制剂AG014699对人卵巢癌细胞株SKOV3增殖及凋亡的影响

目的探讨PARP-1抑制剂AG014699对人卵巢癌细胞株SKOV3`增殖及凋亡的影响。方法①采用MTT法测定AG014699在不同浓度、不同时间对人卵巢癌细胞株SKOV3增殖作用的影响;②用流式细胞仪测定AG014699在50μmol/L浓度下对人卵巢癌细胞株SKOV3作用24h后对细胞周期及凋亡的影响。结果①MTT测定:在24、48、72h时AG014699在10μmol/L分别测得的OD值与对照组相比,P<0.05,有统计学差异;②流式细胞仪测定:AG014699在50μmol/L浓度下对SKOV3作用24h能明显改变细胞的周期分布,诱导细胞凋亡。结论 AG014699能明显抑制人卵巢癌细胞株SKOV3的增殖并诱导其凋亡。     

15d-PGJ_2对肝星状细胞增殖和凋亡的影响

目的观察15d-PGJ2上调过氧化质体增殖物激活受体γ(PPARγ)表达以及对肝星状细胞(hepatic stellate cell,HSC)增殖凋亡的影响。方法体外培养HSC-T6细胞,取对数生长期的细胞,应用1、2、3μmol.L-1不同浓度的PPARγ激动剂15d-PGJ2作用24h,同时以不加药物只加无血清培养基做为对照组,24h后应用RT-PCR的方法观察分析各组间肝星状细胞PPARγ mRNA表达的变化,Western blot检测相应的胞质内NF-κB抑制蛋白表达。MTT检测HSC增殖,吖啶橙荧光染色观察细胞凋亡,流式细胞仪分析细胞周期。结果经15d-PGJ2处理的HSC细胞中PPARγ mRNA表达比例上调;胞质内NF-κB蛋白表达明显抑制。MTT结果显示不同浓度的15d-PGJ2对HSC-T6细胞的增殖均有抑制作用,以2μmol.L-1组最为明显;吖橙啶染色显示经PPARγ激动剂处理组凋亡细胞数明显增多,流式细胞仪结果显示15d-PGJ2处理组细胞产生了G1期阻滞作用。结论15d-PGJ2能够上调PPARγ表达并抑制HSC-T6增殖及诱导其凋亡,其诱导凋亡机制可能与抑制NF-κB活性有关。     

全反式维甲酸对小细胞肺癌细胞的分化诱导作用研究

目的探讨全反式维甲酸(all-trans-retinoic acid,ATRA)对小细胞肺癌细胞的分化诱导作用。方法选择NCI-H446细胞株MTT法检测细胞体外增殖能力,电镜下观察形态,流式细胞仪进行细胞周期分析。RT-PCR法分析维甲酸受体亚型基因。结果全反式维甲酸诱导小细胞肺癌NCI-H446细胞株,细胞增殖能力下降,凋亡增加,更多的细胞被阻止于G1/G0期。结论全反式维甲酸诱导分化能有效抑制小细胞肺癌NCI-H446细胞株的增殖,促进凋亡。     

The tyrphostin AG1478 inhibits proliferation and induces death of liver tumor cells through EGF receptor-dependent and independent mechanisms

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death. Different signaling pathways are de-regulated in this pathogenesis, among them the epidermal growth factor receptor one (EGFR/Erb1). Here we show that blockage of this pathway by the tyrphostin 4-(3-chloroanilino)-6,7-dimethoxyquinazoline (AG1478) in different liver tumor cell lines promotes both inhibition of cell proliferation and induction of cell death, which are coincident with arrest in the G1 phase of the cell cycle, caspase-3 activation and DNA fragmentation. AG1478 up-regulates the expression of the pro-apoptotic member of the BCL-2 family BIM and down-regulates the expression of the anti-apoptotic BCL-XL and MCL1. Furthermore, it also decreases the levels of the caspase inhibitors HIAP2 and XIAP. The treatment of HCC cells with AG1478 enhanced the apoptosis induced by other pro-apoptotic stimuli, such as the physiological cytokine, TGF-β, highly expressed in liver tumors, or the chemotherapeutic drug doxorubicin. The effects observed by AG1478 were broader than the ones seen by silencing of the EGFR with siRNA, which indicates that this drug might act on other targets different from the EGFR. In this same line of evidence, AG1478 retained some cytotoxic effects in cells where EGFR has been targeted knock-down with shRNA. Interestingly, AG1478 preferentially acts on liver tumor cells, being untransformed cells much less responsive to its cytotoxic effects. In conclusion, AG1478 could be a potential therapeutic drug to be used in HCC.     

曲古抑菌素A对肾癌细胞系GRC-1生长的抑制作用

目的 研究组蛋白去乙酰化酶(HDAC)抑制药曲古抑菌素A(TSA)对肾癌GRC-1细胞生长的影响及其作用机制. 方法使用TSA处理GRC-1细胞. 噻唑蓝(MTT)法检测细胞生长;流式细胞仪分析细胞凋亡及细胞周期;Western blot免疫印迹分析p53,p21和bcl-2表达. 结果 TSA能明显抑制GRC-1细胞的增殖,且具有明显的剂量依赖性;TSA处理72 h的GRC-1细胞早期凋亡率明显提高,G0/G1期细胞比例显著升高,S期细胞比例显著降低. TSA能够明显下调bcl-2的表达,上调p21的表达,而对p53的没有显著影响. 结论TSA可以通过诱导肾肿瘤细胞的凋亡和周期阻滞而抑制癌细胞生长;其发生机制可能与下调抗凋亡基因bcl-2和上调肿瘤抑制基因p21的表达有关,TSA可能依赖非p53途径调控p21的表达.     

EGFR-dependent ERK activation triggers hydrogen peroxide-induced apoptosis in OK renal epithelial cells

Oxidative stress induces activation of extracellular signal-regulated kinase (ERK), a member of the mitogen-activated protein kinase families. However, it is unclear in renal epithelial cells whether the ERK activation is involved in cell survival or cell death in H₂O₂-treated cells. The present study was undertaken to determine the role of the ERK activation in H₂O₂-induced apoptosis of renal epithelial cells using opossum kidney (OK) cells, an established proximal tubular epithelial cell line. H₂O₂ resulted in a time- and dose-dependent apoptosis of OK cells. H₂O₂ treatment caused marked sustained activation of ERK. The ERK activation was prevented by PD98059 and U0126, inhibitors of ERK1/2 upstream kinase MEK1/2. Apoptosis caused by H₂O₂ was prevented by U0126. Transient transfection with constitutive active MEK1 increased the H₂O₂-induced apoptosis, whereas transfection with dominant-negative mutants of MEK1 decreased the apoptosis. H₂O₂ produced hyperpolarization of mitochondrial membrane potential and activation of caspases-3. H₂O₂-induced ERK activation was inhibited by the Src family selective inhibitor PP2 and the epidermal growth factor receptor inhibitor AG1478. The presence of AG1478, but not PP2, prevented H₂O₂-induced cell death. Taken together, our findings suggest that the ERK activation mediated by epidermal growth factor receptor plays an active role in inducing H₂O₂-induced apoptosis of OK cells and functions upstream of mitochondria-dependent pathway to initiate the apoptotic signal.     

Thrombin-induced p38 mitogen-activated protein kinase activation is mediated by epidermal growth factor receptor transactivation pathway

Thrombin is a potent mitogen for vascular smooth muscle cells (VSMC) and has been implicated its pathogenic role in vascular remodelling. However, the signalling pathways by which thrombin mediates its mitogenic response are not fully understood. We have previously reported that thrombin activates p38 mitogen-activated protein kinase (p38 MAPK) by a tyrosine kinase-dependent mechanism, and that p38 MAPK has a role in thrombin-induced mitogenic response in rat VSMC. In the present study, we examine the involvement of epidermal growth factor (EGF) receptor in thrombin-induced p38 MAPK activation. We found that thrombin induced EGF receptor tyrosine phosphorylation (transactivation) in A10 cells, a clonal VSMC cell line. A selective inhibitor of EGF receptor kinase (AG1478) inhibited the p38 MAPK activation in a dose-dependent manner, whereas it had no effect on the response to platelet-derived growth factor (PDGF). EGF receptor phosphorylation induced by thrombin was inhibited by BAPTA-AM and GF109203X, which suggest a requirement for intracellular Ca(2+) increase and protein kinase C. We next examined the effect of AG1478 on thrombin-induced DNA synthesis. AG1478 inhibited thrombin-induced DNA synthesis in a dose-dependent manner. In contrast, PDGF-induced DNA synthesis was not affected by AG1478. In conclusion, these data suggest that the EGF receptor transactivation and subsequent p38 MAPK activation is required for thrombin-induced proliferation of VSMC.     

EGF receptor transactivation in angiotensin II and endothelin control of vascular protein synthesis in vivo

Endothelin represents a necessary intermediate of angiotensin II-induced resistance artery remodeling in hypertension. Recent data suggest that epidermal growth factor receptors are rapidly transactivated by angiotensin II stimulation to mediate its growth-promoting effects. Because endothelin also transactivates epidermal growth factor receptors in vitro, we studied the contribution of epidermal growth factor receptor transactivation in the in vivo trophic actions of the upstream effector angiotensin II and its downstream mediator endothelin in rat mesenteric arteries. Twenty-six-hour infusion of angiotensin II (400 ng/kg per min) or endothelin (5 pmol/kg per min) via osmotic pumps significantly enhanced vascular protein synthesis. With angiotensin II, treatment with the inhibitor of epidermal growth factor receptor transactivation (AG1478, 0.5 mg/kg) produced a significant attenuation (P < 0.05) of protein synthesis. In contrast, AG1478 did not abrogate the elevation of protein synthesis induced by endothelin. In conclusion, angiotensin II-induced epidermal growth factor receptor transactivation seems to be involved in the recruitment of endothelin in the cascade leading to vascular protein synthesis, rather than in the effect of endothelin on small artery remodeling.     

Leptin stimulates endothelin-1 expression via extracellular signal-regulated kinase by epidermal growth factor receptor transactivation in rat aortic smooth muscle cells

Obesity is a major risk factor for the development of hypertension. Recent studies have suggested that leptin, a 167-amino acid peptide hormone produced by white adipose tissue, is related to the pathogenesis of obesity-related hypertension. However, the signaling mechanisms underlying the effects of leptin remain to be extensively examined. In this study, we found that leptin induced extracellular signal-regulated kinase phosphorylation and endothelin-1 expression in rat aortic smooth muscle cells. Both PD98059 and U0126, inhibitors of the upstream activator of mitogen-activated protein kinase kinase, inhibited augmentation of endothelin-1 expression stimulated with leptin. Leptin induced significant tyrosine phosphorylation of epidermal growth factor receptor, which was significantly attenuated by two inhibitors, an epidermal growth factor receptor tyrosine kinase inhibitor, AG1478, and a broad-spectrum matrix metalloproteinase inhibitor, GM6001. This indicates that the pathway of epidermal growth factor receptor transactivation induced by leptin is dependent on proteolytically released epidermal growth factor receptor ligands. Pretreatment of cells with AG1478 significantly reduced the degree of phosphorylation of extracellular signal-regulated kinase and endothelin-1 expression. Our results reveal that epidermal growth factor receptor transactivation is involved in the leptin signaling pathway in vascular smooth muscle cells, which may be related to the increased risk of hypertension and other cardiovascular diseases in obese subjects.     

Endosomal signalling of epidermal growth factor receptors contributes to EGF-stimulated cell cycle progression in primary hepatocytes

Agonist-induced internalisation of receptors may lead to the formation of signalling endosomes. There is little evidence relating to whether this occurs to native receptors in non-transformed cells, and no previous studies asking whether this endosomal signalling can promote cell cycle progression in non-transformed cells. We investigated the hypothesis that in primary hepatocytes clathrin-dependent epidermal growth factor (EGF)-induced internalisation of the EGF receptor leads to signalling from endosomal EGF–EGF receptor complexes which may support EGF-stimulated cell cycle progression. We used EGF-stimulation of rat hepatocytes followed by confocal microscopy, and Western blots for phosphoproteins. [³H]thymidine incorporation into DNA was used as a indicator of progression to S-phase. Confocal microscopy demonstrated co-internalisation of EGF, EGF receptors and transferrin into endosomes. Internalisation of EGF/EGF receptor/transferrin was blocked by expression of dominant-negative dynamin, but not by the tyrosine kinase inhibitor AG 1478. Dominant-negative dynamin expression reduced EGF-stimulated extracellular signal-related kinase and Akt signalling, but increased tyrosine phosphorylated EGF receptor. EGF-stimulated cell cycle progression requires stimulation of EGF receptors during an initial period (e.g. 1 h) and also later during a 24 h incubation. EGF receptor internalisation in the presence of AG 1478 followed by removal of the inhibitor resulted in signalling from internalised EGF receptors that is sufficient for the initial stimulation to provide progression to S-phase of the cell cycle. These observations on hepatocytes characterise, for the first time in non-transformed cells, endosomal signalling from internalised EGF receptors, and provide evidence that this endosomal signalling may support the early phase of EGF-stimulated cell cycle progression.     

Induction of Cdc25B expression by epidermal growth factor and transforming growth factor-alpha

The dual specificity protein phosphatase Cdc25B regulates of the mitotic cell cycle checkpoint and is over expressed in human tumors. Given the importance of growth factors in initiating and sustaining cell proliferation, we examined their effects on Cdc25B protein expression in human cancer cells. Within 1h after epidermal growth factor (EGF) or transforming growth factor-alpha (TGF-alpha) treatment, Cdc25B protein levels increased in growth factor responsive A549 and SCC25 cells, but not in non-responsive MDA-MB-231 cells. A functional consequence of elevated Cdc25B was implied by the concomitant decrease in phosphorylated cyclin dependent kinase, a known Cdc25B substrate, after growth factor treatment of A549 and SCC25 cells. The EGF-mediated induction of Cdc25B required a functional EGF receptor (ErbB1), as mouse embryonic fibroblasts lacking ErbB1 did not have increased Cdc25B levels after EGF treatment. Moreover, the EGFR receptor-selective tyrosine kinase inhibitor AG1478 and mitogen activated kinase kinase inhibitor U0126 blocked growth factor-mediated Cdc25B induction. Thus, EGF and TGF-alpha appear to induce cellular Cdc25B through the mitogen-activated protein kinase pathway.