Proteasome inhibition induces a senescence-like phenotype in primary human fibroblasts cultures

Senescent human fibroblasts exhibit several genetic and biochemical differences as compared to their young counterparts including abnormalities of the main proteolytic mechanism, namely the proteasome. Specifically, we and others have shown that there is an impaired function of the proteasome, as senescent cells have reduced proteolytic activities and less proteasome content. In a complementary work we have recently shown that inhibition of the proteasome by a specific inhibitor induces a senescence-like phenotype in young WI38 fibroblasts [Chondrogianni et al. (2003) J Biol Chem 278: 28026-28037]. In this study we tested whether the induction of a senescence-like phenotype following treatment with proteasome inhibitors is a common feature of primary human fibroblasts. A comparative biochemical analysis, after employing three different human fibroblasts cell lines (IMR90, MRC5 and WI38 cells), as well as two proteasome inhibitors (epoxomicin and MG132), has shown that proteasome inhibition results in the appearance of a senescence-like phenotype in all cell lines used. Proteasome inhibitors treated cells were irreversibly stopped dividing, exhibited positive staining to beta-galactosidase as well as reduced CT-L and PGPH activities. In summary, these data reveal the fundamental role of the proteasome in the progression of replicative senescence and open new dimensions towards a better understanding of protein degradation.     

Effect of mutant p27kip1 gene on human cholangiocarcinoma cell line, QBC939

AIM:To investigate the effects of exogenously mutated p27kip1 (p27) on proliferation and apoptosis of human cholangiocarcinoma cell line,QBC939 in vivo.METHODS:Adenviral vectors were used to transfect mutated p27 cDNA into human QBC939 cell line.Expression of p27 was detected by RT-PCR.Western blot.Cell growth,morphological change,cell cycle,apoptosis and cloning formation were determined by MTT assay and flow cytometry.RESULTS:The expression of p27 protein and mRNA was increased significantly in QBC939 cell line transfected with Ad-p27mt.The transfer of Adp27mt could significantly inhibit the growth of QBC939cells,decrease the cloning formation rate and induce apoptosis,p27 over expression caused cell cycle arrest at G0/G1 phase 72 h after infection with Adp27mt.CONCLUSION:p27 may cause cell cycle arrest at G0/G1 phase and subsequently lead to apoptosis.Recombinant adenovirus expressing mutant p27 may be potentially useful in gene therapy for cholangiocarcinoma.     

Effect of mutant p27(kipl) gene on human cholangiocarcinoma cell line, QBC(939)

AIM：To investigate the effects of exogenously mutated p27^kip1 （p27） on proliferation and apoptosis of human cholangiocarcinoma cell line, QBC939 in vivo.METHODS： Adenviral vectors were used to transfect mutated p27 cDNA into human QBC939 cell line. Expression of p27 was detected by RT-PCR. Western blot. Cell growth, morphological change, cell cycle, apoptosis and cloning formation were determined by MTT assay and flow cytometry.RESULTS： The expression of p27 protein and mRNA was increased signifi cantly in QBC939 cell line transfected with Ad-p27mt. The transfer of Ad-p27mt could signifi cantly inhibit the growth of QBC939 cells, decrease the cloning formation rate and induce apoptosis. p27 over expression caused cell cycle arrest at G0/G1 phase 72 h after infection with Ad-p27mt.CONCLUSION： p27 may cause cell cycle arrest at G0/G1 phase and subsequently lead to apoptosis. Recombinant adenovirus expressing mutant p27 may be potentially useful in gene therapy for cholangiocarcinoma.     

Apoptosis of human cholangiocarcinoma cells induced by ESC-3 from Crocodylus siamensis bile

AIM: To investigate the effects of ESC-3 isolated from crocodile bile on the growth and apoptosis induction of human cholangiocarcinoma cells.METHODS: ESC-3 was isolated from crocodile bile by Sephadex LH-20 and RP-18 reversed-phase column. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay was conducted to determine the effects of ESC-3 on the proliferation of human cholangiocarcinoma cell lines (QBC939, Sk-ChA-1 and MZ-ChA-1). Giemsa staining, Hoechst 33258 and acridine orange/ethidium bromide staining showed the morphological changes of Mz-ChA-1 cells exposed to ESC-3 at different concentrations. Flow cytometry with regular propidium iodide (PI) staining was performed to analyze the cell cycle distribution of Mz-ChA-1 cells and to assess apoptosis by annexin v-fluorescein isothiocyanate (V-FITC)/PI staining. Rh123 staining was used to detect the alteration of mitochondrial membrane potential (ΔΨm). The protein levels of Bax, Bcl-2, Cdk2, cytochrome c and caspase-3 were further confirmed by Western blotting.RESULTS: ESC-3 significantly inhibited the growth of three human cholangiocarcinoma cell lines and arrested Mz-ChA-1 cell cycle at G0/G1 phase. Mz-ChA-1 cells showed typical apoptotic morphological changes after treated with ESC-3 (10 μg/mL) for 48 h. Cell death assay indicated that Mz-ChA-1 cells underwent apoptosis in a dose-dependent manner induced by ESC-3. In addition, ESC-3 treatment could downregulate the protein level of Bcl-2 and upregulate the Bax, leading to the increase in the ratio of Bax to Bcl-2 in Mz-ChA-1 cells. Meanwhile, cytochrome c was released from the mitochondria into the cytosol, which subsequently initiated the activation of caspase-3. All these events were associated with the collapse of the mitochondrial membrane potential.CONCLUSION: ESC-3, the active ingredient of crocodile bile, induced apoptosis in Mz-ChA-1 cells through the mitochondria-dependent pathway and may be a potential chemotherapeutic drug for the treatment of cholangiocarcinoma.     

内质网应激及其相关性凋亡在多巴胺能神经元选择性变性死亡中的作用

目的探讨内质网应激反应（endoplasmic retieulum stress response，ERS）及相关凋亡途径在多巴胺能神经元变性死亡中的作用。方法6羟基多巴胺（6-OHDA）、N-甲基-4苯基吡啶离子（MPP^＋）、鱼藤酮作用于神经生长因子（NGF）诱导的PC12细胞，MTT及流式细胞仪方法检测各种药物的神经毒性作用及细胞凋亡率，应用RT-PCR和Western印迹技术观察以上药物处理后ERS通路中XBP1、Grp78、CHOP表达水平的变化及相关凋亡因子caspase-12的活化和利血平耗竭胞内多巴胺水平后的影响。结果3种神经诱变剂处理PC12细胞后，细胞活力呈浓度依赖性下降，其中6-OHDA 100μmol／L、MPP^＋ 75μmol／L、鱼藤酮20nmol／L作用24h使细胞活力分别下降52％、44％、40％。流式细胞仪显示的细胞凋亡率在8h、16h、24h内逐渐增高（P〈0．01）。RT—PCR及免疫组化检测显示处理后XBP1、Grp78表达和CHOP的基因及蛋白表达水平明显增加，分别在8h、16～24h达到高峰（P〈0．01）。caspase-12 mRNA水平也在诱导后16h显著升高（P〈0．01），利血平预处理使其基因表达减弱（P〈0．05）。结论内质网应激和相关凋亡途径是多巴胺能神经元选择性变性死亡的内在环节之一。     

蛋白酶体抑制剂MG132对结肠癌细胞lovo侵袭力的影响

目的探讨小剂量蛋白酶体抑制剂MG132对结肠癌细胞(lovo)侵袭能力的影响。方法采用不同浓度MG132不同时间点分别作用于lovo细胞,用四甲基偶氮盐比色法(MTT法)检测lovo细胞抑制率;设定MG132浓度为0.5μmol/L、1μmol/L,分别作用lovo细胞24 h,倒置显微镜观察细胞形态学变化,Transwell小室检测MG132对lovo细胞的穿透基底膜能力的影响。结果低剂量MG132对lovo细胞生长无明显抑制,而细胞侵袭力较未处理组明显减弱(P<0.05)。结论低剂量MG132可使结肠癌lovo细胞侵袭能力减弱。     

WWOX基因转染对胆管癌细胞增殖、凋亡及侵袭的影响

目的:探讨WWOX基因转染胆管癌细胞株QBC939后对其增殖、凋亡与侵袭性的影响.方法:用脂质体转染法将WWOX重组真核表达质粒转染QBC939细胞,建立稳定表达WWOX基因的细胞株.将其分为以下3组:QBC939组,QBC939/con组和QBC939/WWOX组.荧光定量RT-PCR和Western blot法检测...     

Molecular mechanisms of cholangiocarcinoma

Cholangiocarcinoma (CC), the malignant tumor of the epithelial cells lining the biliary ducts, has undergone a worldwide increase in incidence and mortality. The malignant transformation of the biliary cells originates from a multistep process evolving through chronic inflammation of the biliary tract to CC. In the last few years several advances have been towards understanding and clarifying the molecular mechanisms implicated in the cholangiocarcinogenesis process. However, many pathophysiologic aspects governing the growth of CC are still undefined. The poor prognosis of this tumor underlines the urgent need to codify the underlying molecular mechanisms involved in the growth and progression of CC in order to design effective preventive measures and valid treatment regimens. This review reports on progresses made in the last few years in clarifying the molecular pathways involved in the process of cholangiocarcinogenesis.     

丝裂霉素诱导凋亡癌细胞致敏树突状细胞后的免疫应答

目的 观察树突状细胞(DC)从丝裂霉素诱导的凋亡胆管癌细胞获取抗原后,抗肿瘤免疫应答及对胆管癌细胞的特异性免疫杀伤效果。 方法 用粒细胞-巨噬细胞集落刺激因子(GM-CSF)加IL-4从人外周血分化、诱导DC,丝裂霉素在体外诱导培养的人胆管癌细胞凋亡,将DC、T淋巴细胞和凋亡胆管癌细胞共培养,同时设计不同类型肿瘤细胞(坏死胆管癌细胞及培养胆管癌细胞)作对照,7d后,分离、富集DC、T淋巴细胞进行免疫应答及肿瘤细胞杀伤试验。 结果 与凋亡胆管癌细胞共培养的DC可以有效提呈胆管癌细胞抗原,有强烈的免疫应答,刺激的细胞毒T淋巴细胞特异性地杀伤胆管癌细胞。 结论 丝裂霉素诱导凋亡癌细胞可以致敏rhGM-CSF加rhIL-4从人外周血单个核细胞诱导、扩增出的DC,并产生显著的杀伤胆管癌细胞的免疫反应,可望成为特异性免疫治疗肿瘤的一条新途径。     

Differential regulation of apoptotic cell death in senescent human cells

Aging of human cells can be reproduced in monolayer cultures, revealing the phenotype of replicative senescence. It was shown that diploid human fibroblasts enter a stable growth arrest phenotype at the end of their lifespan and, in particular, these cells are resistant to various apoptotic stimuli. In contrast, human endothelial cells from the umbilical vein (HUVEC) acquire a proapoptotic phenotype when reaching senescence and this probably results from reactive oxygen species (ROS) induced damage and associated signaling. Ceramides were shown to accumulate in senescent fibroblasts and are also known as potent regulators of apoptotic cell death. To further study age-associated changes in proneness to apoptosis between fibroblasts and endothelial cells, both cell types were challenged by administration of exogenous ceramide and apoptotic cell death was determined. While ceramide can efficiently induce apoptosis in both young and senescent cells of either histotype, quantitative evaluation of the data show that senescent fibroblasts are more resistant to apoptosis induction when compared to their young counterparts, whereas in the case of endothelial cells proneness for apoptosis is increased in senescent cells. Together, these data suggest significant differences in the regulation of apoptosis associated with senescence in fibroblasts and endothelial cells.     

N-乙酰半胱氨酸对内质网应激介导的HepG2细胞凋亡的作用

目的 了解N-乙酰半胱氨酸(NAC)对内质网氧化应激介导的肝细胞凋亡的阻抑作用,探讨其治疗肝细胞损伤的作用机制.方法 用过氧化氢(H2O2)诱导HepG2细胞,建立内质网氧化应激凋亡模型,用NAC进行干预.通过四甲基偶氮唑盐、DNA梯度分析,Western blot、流式细胞仪检测细胞凋亡率及活性氧(ROS)的产生等方法,了解NAC对H2O2诱导HepG2细胞的凋亡率、凋亡信号蛋白的表达以及ROS产生的影响.结果 用不同浓度H2O2(0、1、3,5 mmol/L)诱导HepG2细胞6 h后,发现随着H2O2浓度增加,细胞活力下降,凋亡率增加,分别为0.7%±0.5%、26.4%±1.8%、29.7%±1.2%、51.2%±9.4%;细胞凋亡信号蛋白表达增加,ROS产生增多,分别为14.0%±0.5%、95.2%±0.1%、97.5%±0.25%、98.3%±0.2%;在3 mmol/L时出现典型内质网氧化应激凋亡形态学改变.用NAC(10、20 mmol/L)干预后发现,NAC可明显提高细胞活力、细胞凋亡率由29.7%±1.2%降至23.3%±4.7%和14.3%±1.2%,细胞凋亡过程中凋亡信号蛋白的表达减少、细胞内ROS的产生率由97.5%±0.2%降至52.2%±0.8%和51.2%±2.9%.结论 NAC能对氧自由基反应有直接抑制作用,阻断内质网氧化应激介导的肝细胞凋亡,减轻肝细胞损伤.     

内质网应激与慢性阻塞性肺疾病

内质网应激(endoplasmic reticulum stress,ERS)反应是由于多种应急原引起的细胞内质网功能障碍,导致内质网腔内错误折叠、未折叠蛋白聚集和钙离子平衡紊乱,细胞为恢复内质网功能而进行的一系列调节反应.ERS广泛参与多种疾病的发病机制,是一把介导细胞适应性生存和凋亡/自噬的双刃剑.肺结构细胞凋亡是慢性阻塞性肺疾病发生、发展的重要机制.近年的研究表明,ERS在慢性阻塞性肺疾病肺结构细胞凋亡机制中发挥了重要的作用.     

替米沙坦对糖尿病大鼠肾脏组织中内质网应激介导相关细胞凋亡的保护作用

探讨血管紧张素Ⅱ受体拮抗剂对糖尿病大鼠肾脏组织中内质网应激相关的细胞凋亡的影响.31只雄性SD大鼠分为正常对照组、糖尿病组、替米沙坦干预组.12周试验结束后测量大鼠体重、24h尿蛋白量,检测血糖、血胰岛素、血肌酐等.肾脏细胞凋亡用TUNEL法检测;肾脏细胞内质网应激信号通路分子糖调节蛋白78( GRP78)、caspase12和CHOP用免疫组化及实时定量PCR法检测.糖尿病组的血糖、24h尿蛋白量、血肌酐显著高于对照组(P＜0.05);体重和血胰岛素较对照组低(P＜0.05).替米沙坦干预组的24h尿蛋白量、血肌酐较糖尿病组明显减少(P＜0.05),凋亡指数也显著低于糖尿病组(P＜0.05).大鼠内质网应激信号通路分子GRP78、caspase12、CHOP蛋白及其mRNA的表达,糖尿病组显著高于对照组和替米沙坦干预组(P＜0.05).内质网应激参与了糖尿病大鼠肾脏细胞的凋亡,替米沙坦对内质网应激介导相关的肾脏细胞凋亡有保护作用.     

Histone deacetylase inhibitor MS-275 alone or combined with bortezomib or sorafenib exhibits strong antiproliferative action in human cholangiocarcinoma cells

AIM: To investigate the antiproliferative effect of the histone deacetylase (HDAC) inhibitor MS-275 on cholangiocarcinoma cells alone and in combination with conventional cytostatic drugs (gemcitabine or doxorubicin) or the novel anticancer agents sorafenib or bortezomib. METHODS: Two human bile duct adenocarcinoma cell lines (EGI-1 and TFK-1) were studied. Crystal violet staining was used for detection of cell number changes. Cytotoxicity was determined by measuring the release of the cytoplasmic enzyme lactate dehydrogenase (LDH). Apoptosis was determined by measuring the enzyme activity of caspase-3. Cell cycle status reflected by the DNA content was detected by flow cytometry.RESULTS: MS-275 treatment potently inhibited the proliferation of EGI-1 and TFK-1 cholangiocarcinoma cells by inducing apoptosis and cell cycle arrest. MS-275-induced apoptosis was characterized by activation of caspase-3, up-regulation of Bax and down-regulation of Bcl-2. Cell cycle was predominantly arrested at the G1/S checkpoint, which was associated with induction of the cyclin-dependent kinase inhibitor p21Waf/CIP1. Furthermore, additive anti-neoplastic effects were observed when MS-275 treatment was combined with gemcitabine or doxorubicin, while combination with the multi-kinase inhibitor sorafenib or the proteasome inhibitor bortezomib resulted in overadditive anti-neoplastic effects.CONCLUSION: The growth of human cholangiocarcinoma cells can be potently inhibited by MS-275 alone or in combination with conventional cytostatic drugs or new, targeted anticancer agents.     

Controlling metabolism and cell death: At the heart of mitochondrial calcium signalling

Transient increases in intracellular calcium concentration activate and coordinate a wide variety of cellular processes in virtually every cell type. This review describes the main homeostatic mechanisms that control Ca²⁺ transients, focusing on the mitochondrial checkpoint. We subsequently extend this paradigm to the cardiomyocyte and to the interplay between cytosol, endoplasmic reticulum and mitochondria that occurs beat-to-beat in excitation–contraction coupling. The mechanisms whereby mitochondria decode fast cytosolic calcium spikes are discussed in the light of the results obtained with recombinant photoproteins targeted to the mitochondrial matrix of contracting cardiomyocytes. Mitochondrial calcium homeostasis is then highlighted as a crucial point of convergence of the environmental signals that mediate cardiac cell death, both by necrosis and by apoptosis. Altogether we point to a role of the mitochondrion as an integrator of calcium signalling and a fundamental decision maker in cardiomyocyte metabolism and survival.