Endothelin-receptor antagonists are proapoptotic and antiproliferative in human colon cancer cells

Endothelin (ET)-1 can act as an autocrine/paracrine growth factor or an antiapoptotic factor in human cancers. To study the role of ET-1 in human colon cancer, proliferation and apoptosis of colon carcinoma cells was investigated using human HT-29 and SW480 colon carcinoma cells. ET-1 was secreted by these cells. Treatment of cells with bosentan, a dual ET(A/B)-receptor antagonist, decreased cell number. Inhibition of DNA synthesis by bosentan was observed only in the presence of serum. Exogenously added ET-1 did not increase DNA synthesis in serum-deprived cells. SW480 cells were sensitive and HT-29 cells were resistant to FasL-induced apoptosis. Bosentan sensitised resistant HT-29 cells to FasL-induced, caspase-mediated apoptosis, but not to TNF-alpha-induced apoptosis. Bosentan and/or FasLigand (FasL) did not modulate the expression of caspase-8 or FLIP. Bosentan sensitisation to apoptosis was reversed by low concentrations (10(-13)-10(-10) M), but not by high concentrations (10(-9)-10(-7) M) of ET-1. These results suggest that the binding of ET-1 to high-affinity sites inhibits FasL-induced apoptosis, while the binding of either ET-1 or receptor antagonists to low-affinity sites promotes FasL-induced apoptosis. In conclusion, endothelin signalling pathways do not induce human colon cancer cell proliferation, but are survival signals controling resistance to apoptosis.     

PRDX1在蛋白酶体抑制剂诱导人甲状腺癌细胞凋亡中的作用

目的:探讨过氧化还原蛋白(Peroxiredoxin1,PRDX1)在蛋白酶体抑制剂诱导人甲状腺癌细胞凋亡中的作用。方法:选取人甲状腺癌细胞,设立对照组和蛋白酶体抑制剂处理组;实时定量PCR法、蛋白印迹法检测PRDX1在各组甲状腺癌细胞中的表达;微小RNA干扰技术、过表达PRDX1质粒转染细胞;应用流式细胞仪检测细胞凋亡。结果:与对照组相比,MG132处理组中PRDX1 mRNA及蛋白表达水平显著增加(P<0.01);蛋白酶体抑制剂组、siPRDX1组PRDX1 mRNA及蛋白显著低于随机序列组及空白组(P<0.05);siPRDX1转染细胞组中细胞凋亡率显著高于随机序列组及空白组(P<0.05);在8305C和8505C细胞中也得到相似的结果;siPRDX1+PRDX1表达载体组对MG132介导的凋亡无显著影响(P>0.05)。结论:siPRDX1增加蛋白酶体抑制剂对未分化甲状腺癌细胞的凋亡作用,而这种作用可以被外源性PRDX1所抑制。     

食欲素诱导结肠癌细胞凋亡机制的研究

食欲素(orexin)是下丘脑分泌的一种新型神经肽,具有调节摄食行为、能量代谢、睡眠与觉醒等生理作用.近年来,多项研究证实食欲素可以促进肿瘤细胞的凋亡,尤以结肠癌细胞研究较多.本文欲从食欲素与结肠癌的研究现状及促进结肠癌细胞凋亡机制方面进行阐述.     

氧化应激对蛋白酶体抑制剂诱导甲状腺癌细胞凋亡影响的研究

目的:探讨氧化应激在启动蛋白酶体抑制剂诱导甲状腺癌细胞凋亡中的作用.方法:选取4种人甲状腺未分化癌细胞系ARO、FRO、KTC2和8305C,分别设空白对照组、万珂处理组和万珂+钛剂联合组;流式细胞仪(FCM)检测细胞凋亡情况;Caspase-3活性测试法检测各组细胞Caspase-3活性;用荧光分光光度计法检测各组细胞蛋白酶体活性和细胞内ROS水平.结果:与空白对照组相比,蛋白酶体抑制剂万珂对人甲状腺癌细胞系FRO和KTC2具有很强的细胞凋亡诱导作用;使FRO和KTC2细胞中Caspase-3的活性显著增高,P＜0.01;可持续快速抑制蛋白酶体活性,但在4组细胞中差异无统计学意义,P＞0.05;万珂可显著提高活性氧簇在FRO和KTC2甲状腺癌细胞中的表达.万珂组与万珂+钛剂组活性氧簇水平在4种甲状腺癌细胞中差异均有统计学意义,P＜0.05;在FRO和KTC2甲状腺癌细胞中,万珂组与万珂+钛剂组中的细胞凋亡率差异有统计学意义,P＜0.01.结论:蛋白酶体抑制剂可以提高活性氧簇在甲状腺未分化癌细胞中的表达,促进肿瘤细胞的凋亡,并且这种效应可以被抗氧化剂所抑制.     

Inhibition of proteasome function induced apoptosis in gastric cancer

The ubiquitin-proteasome pathway plays a critical role in the degradation of cellular proteins and cell cycle control. Dysregulating the degradation of such proteins should have profound effects on tumor growth and causes cells to undergo apoptosis. The aims of this study are to evaluate the ubiquitin-proteasome pathway in gastric cancer and the potential role of pharmacological inhibition of proteasome on induction of apoptosis in gastric cancer cells. Gastric cancer cell lines AGS (p53 wild-type) and MKN-28 (p53 mutant) were treated with proteasome inhibitor MG132. The results showed that MG132 inhibited cell proliferation in AGS and MKN-28 cells in a time- and dose-dependent manner. The inhibition of cell proliferation was caused by apoptosis which was also time- and dose-dependent. AGS cells were more responsive to MG132 than MKN-28 cells. Induction of apoptosis was preceded by the activation of caspase-3, as measured by a colorimetric caspase-3 cellular activity and Western blotting of the cleavage of caspase-3 and its substrate PARP. Activation of caspase-7 was also exhibited. In addition, z-VAD-fmk, a broad spectrum caspase inhibitor, reversed apoptosis induced by MG132 in AGS and MKN28 cells. Although z-DEVD-fmk, a specific caspase-3 inhibitor, suppressed MG132-induced apoptosis in MKN28 cells, it only partially rescued the apoptotic effect in AGS cells. Caspase-3 activation was the result of release of cytochrome c from mitochondria into the cytosol, as a consequence of upregulation of bax. There were overexpressions of all the proteasome-related proteins p53, p21(waf1) and p27(kip1) at 4 hr after proteasome inhibition which was identified by the accumulation of ubiquitin-tagged proteins. This was accompanied by accumulation of cells at G(1) phase. Our present study suggests that inhibition of proteasome function in gastric cancer cells induces apoptosis and proteasomal inhibitors have potential use as novel anticancer drugs in gastric cancer.     

PRDX1抑制蛋白酶体抑制剂诱导人甲状腺癌细胞凋亡机制探讨

目的：初步探讨过氧化还原蛋白1（peroxirodoxin1,PRDX1）抑制蛋白酶体抑制剂诱导人甲状腺癌细胞凋亡的机制。方法：选取人甲状腺癌细胞,设立随机序列核酸siRNA、siASK1、siPRDX1和siASK1＋siPRDX1组,分别用培养液、lactacystin和MG132培养细胞;用蛋白印迹法检测PRDX1、ASK1、p38、JNK1／2、p-ASK1、p-P38和p-JNK1／2在各组甲状腺癌细胞中的表达;用微小RNA干扰技术转染细胞;应用流式细胞仪检测细胞凋亡率。结果：MG132处理组中,p-ASK1是对照组的1．5倍（F=214．14,P〈0．001）,其下游效应子p-p38和p-JNK1／2分别为对照组的1．34（F=216．75,P〈0．001）和1．94倍（F=1601．68,P〈0．001）;siASK1下调MG132介导的p-ASK1为随机序列组的0．58倍（F=1136．82,P〈O．001）,p-p38为随机序列组的0．73倍（F=507．00,P〈0．001）,p-JNK1／2为随机序列组的0．51倍（F=6087．48,P〈0．001）。甲状腺癌细胞凋亡率降低为34．25％,显著低于于随机序列组的51.98％,F=18．39,P=0．013。MG132处理组中,siPRDX1组甲状腺癌细胞凋亡率为68．99％显著高于随机序列组的49．58％和siPRDX1＋siASK1联合组的41．28％,而siASK1组的甲状腺癌细胞凋亡率为31．85％,显著低于上述两组,组间差异有统计学意义,F=30-13,P〈0．001。结论：PRDX1通过负向调节ASK1活性及ASK1-p38和ASK1-JNK通路,抑制ASK1介导的细胞凋亡进而消减MG132对甲状腺癌细胞毒性效应。     

Simvastatin induces apoptosis in human colon cancer cells and in tumor xenografts, and attenuates colitis-associated colon cancer in mice

Statins, HMG-CoA reductase inhibitors could be associated with the risk reduction of colorectal cancer. We previously demonstrated that simvastatin inhibits NF-kappaB signaling in human intestinal epithelial cells and ameliorates acute murine colitis. The aim of our study was to evaluate the effects of simvastatin on the apoptotic pathways related to NF-kappaB signaling in colon cancer cells, and on anticancer effects in 2 different animal models. We treated cell lines (COLO 205 and HCT 116) with simvastatin or vehicle and determined apoptosis by cell cycle analysis, Annexin V-FITC staining, caspase-3 activity assay and confocal microscopy. We assessed the expression of antiapoptotic factors by RT-PCR and Western blotting. In the colitis-associated colon cancer (CAC) model, we induced colonic tumors in C57/BL6 mice by azoxymethane and dextran sulfate sodium administration, and evaluated simvastatin's effect on tumor growth. In the xenograft model, we evaluated its effect on the inoculated tumor growth. In both cell lines, simvastatin caused dose- and time-dependent cell death. Annexin V staining significantly increased after simvastatin treatment. It augmented caspase-3 activity and downregulated the expression of Bcl-2, Bcl-xL, cIAP1 and cFLIP. In the CAC model, simvastatin significantly reduced tumor development. In the xenograft model, tumors from animals treated with simvastatin had smaller volumes, larger necrotic areas, lower expression of VEGF and higher apoptotic scores. In conclusion, simvastatin inhibited colon cancer development by induction of apoptosis and suppression of angiogenesis. These results suggest that simvastatin could be a potential chemopreventive and therapeutic agent of CAC as well as de novo colon cancer.     

microRNA-224对缺氧诱导结肠癌细胞凋亡的影响

目的:通过结肠癌细胞实验检测microRNA-224在结肠癌发生发展过程中的作用。方法:建立缺氧导致结肠癌细胞凋亡的模型,细胞计数盒(Cell Counting Kit-8,CCK-8)法检测结肠癌细胞活力;Annexin/PI流式细胞术检测结肠癌细胞凋亡率的变化。Annexin/PI流式细胞术检测转染microRNA-224后结肠癌细胞凋亡的变化。蛋白免疫印迹检测转染microRNA-224后凋亡蛋白Caspase-3的变化。结果:凋亡率在缺氧的结肠癌细胞组高于正常结肠癌细胞组(P<0.05);缺氧诱导凋亡组转染microRNA-224后凋亡率低于空质粒对照组(P<0.05);在缺氧诱导凋亡组中转染microRNA-224,凋亡相关蛋白Caspase-3 的表达低于对照组(P<0.05)。结论:microRNA-224可抑制结肠癌细胞凋亡,结肠癌细胞的凋亡失衡在结肠癌的发生发展过程中具有重要意义。     

N6‐isopentenyladenosine inhibits cell proliferation and induces apoptosis in a human colon cancer cell line DLD1

N⁶‐isopentenyladenosine (i6A) is a modified nucleoside with a pentaatomic isopentenyl derived from mevalonate that induces inhibition of tumor cell proliferation and apoptosis in several tumor cell lines. In this study, we reported that N⁶‐isopentenyladenosine inhibited the proliferation and promotes apoptosis in DLD1 human colon cancer cells. It suppressed the proliferation of cells through inhibition of DNA synthesis, causing a cell cycle arrest that correlated with a decrease in the levels of cyclin E, cyclin A and cyclin D1 and with a concomitant increase in the levels of cyclin‐dependent kinase inhibitor p21waf and p27kip1. Moreover, it induced apoptosis through an increase in the number of annexin V‐positive cells, a downregulation of antiapoptotic products and caspase‐3 activation. The apoptotic effects of N⁶‐isopentenyladenosine were accompanied by sustained phosphorylation and activation of c‐jun N‐terminal kinase (JNK) that induced phosphorylation of c‐jun. Overall, our data show that JNK, could play an important role in i6A‐mediated apoptosis in DLD1 human colon cancer cells © 2008 Wiley‐Liss, Inc.     

Beclin 1 在 MG132 抗 OVCAR3 卵巢癌细胞中的变化及作用研究简

目的：研究Beclin1在MG132抗OVCAR3卵巢癌细胞中的变化及作用。方法：OVCAR3细胞经小同浓度MG132处理24h后,MTT法检测细胞存活率,Western blot法检测自噬相关Beclin1蛋白的变化。采用细胞转染技术过表达卵巢癌细胞中Beclin1,MG132处理24h后,MTT法检测细胞存活率;Hoechst33258进行核染色观察染色质浓缩和核碎片等凋亡特征性形态学改变。采用shRNA技术下调OVCAR3细胞的Beclin1表达,MG132处理细胞,AO染色观察酸性自噬泡的形成。结果：与空白对照组比较,1、2、5和10μmol/L浓度的MG132作用24h均能明显抑制OVCAR3细胞的生长（均P〈0．05）,5μmol／L浓度接近半抑制率;而且5μmol／L和10μmol／L浓度的MG132作用24h能显著诱导OVCAR3细胞的Beclin1蛋白水平下降（P=0．001）。与卒质粒转染组对比,过表达Beclin1的卵巢癌细胞在MG132处理后核的凋亡明显增加;细胞存活率明显降低,（P=0．00089）。下调卵巢癌细胞中Beclin1表达后,MG132诱导的酸性囊泡蓄积无改变。结论：MG132使OVCAR3细胞中Beelin1降低,Beclin1具有增强MG132抗OVCAR3的作用,但该怍用与自噬无关。     

叉头盒蛋白A1过表达对SW480细胞增殖和凋亡及EMT形成影响

目的探讨叉头盒蛋白A1(fork-head box protein A1,FOXA1)过表达对结肠癌SW480细胞增殖、凋亡及上皮间质转化(epithelial-mesenchymal transition,EMT)形成的影响,为结肠癌发生发展机制研究提供一定参考。方法收集南京医科大学第一附属医院2014-03-01-2016-10-31结肠癌手术切除癌组织及其配对正常组织标本各50例。体外培养结肠癌细胞SW480、T84、DIFI及人正常结肠上皮细胞NCM460,以随机数字表法分成空白对照组(CK组)、转染含慢病毒载体对照液的阴性对照组(NC组)和转染含FOXA1过表达慢病毒载体的FOXA1过表达(FOXA1过表达组)3组。采用qRT-PCR法检测细胞中FOXA1mRNA表达水平,采用MTT法检测细胞增殖,采用AnnexinⅤ/PI双染法检测细胞凋亡,采用流式细胞术法检测细胞周期,采用蛋白质印迹法检测细胞中FOXA1蛋白及EMT过程相关蛋白的表达。结果结肠癌组织FOXA1mRNA及蛋白表达水平分别为0.42±0.12、0.28±0.07,低于正常组织的1.11±0.24、0.98±0.21,t值分别为18.183、22.361,均P<0.05。结肠癌SW480、T84、DIFI细胞中FOXA1mRNA分别为0.11±0.02、0.14±0.03和0.15±0.03,蛋白表达水平分别为0.34±0.07、0.38±0.09和0.37±0.08,均低于正常上皮细胞的0.27±0.06、0.67±0.09,F值分别为10.259、10.385,P值分别为0.004、0.004;与CK、NC组比较,FOXA1过表达组结肠癌SW480细胞凋亡率(F=32.511)、G0/G1期细胞比例(F=8.860)、FOXA1mRNA(F=325.500)及其蛋白(F=39.670)、E-cadherin(F=37.507)、Cytokeratin蛋白水平(F=14.957)均升高,均P<0.05;24(F=22.407)、48(F=65.290)和72h(F=46.778)的A值、S期细胞(F=11.042)、G2/M期细胞比(F=6.139)、N-cadherin(F=20.746)、Vimentin(F=26.493)、Twist(F=11.024)、β-catenin蛋白(F=29.359)表达水平均降低,均P<0.05。结论过表达FOXA1能够抑制结肠癌SW480细胞增殖,诱导其凋亡,可能抑制结肠癌细胞EMT过程。     

Nrf2对蛋白酶体抑制剂诱导甲状腺癌细胞凋亡影响的观察

目的:红系衍生的核因子2相关因子2(Nrf2)在蛋白酶体抑制剂硼替佐米诱导甲状腺癌细胞凋亡中的作用。方法:选取一系列人甲状腺未分化癌细胞系FRO、KTC1、KTC2、KTC3、8305C和8505C,分别设空白对照组和万珂处理组;蛋白质印迹法检测甲状腺癌细胞中Nrf2蛋白表达情况;共聚焦显微镜检测Nrf2甲状腺癌细胞核定位;流式细胞仪(FCM)检测细胞凋亡情况。结果:与FRO和KTC2细胞相比,Nrf2在人甲状腺癌细胞系8505C和8305C细胞中基础水平呈现高表达,万珂诱导后的表达增加更高,但对万珂诱导的细胞凋亡表现出不敏感,4种细胞的细胞凋亡率分别为(51.98±3.01)%、(46.92±2.72)%、(17.33±4.18)%和(7.97±1.01)%;万珂可诱导8505C和8305C细胞中的Nrf2细胞核易位。结论:Nrf2抑制蛋白酶体抑制剂诱导的甲状腺癌细胞凋亡,其抗凋亡作用可能源于蛋白酶体抑制剂诱导其细胞核转位。     

γ‐Secretase inhibitor I induces apoptosis in chronic lymphocytic leukemia cells by proteasome inhibition,endoplasmic reticulum stress increase and notch down‐regulation

γ‐Secretase inhibitors (GSIs) have been proposed for combined therapies of malignancies with a dysregulated Notch signaling. GSI I (Z‐Leu‐Leu‐Nle‐CHO) induces apoptosis of some tumor cells by inhibiting proteasome and Notch activity. Alterations in these two cell survival regulators contribute to apoptosis resistance of chronic lymphocytic leukemia (CLL) cells. Here, we investigated the mechanisms whereby GSI I increases apoptosis of primary CLL cells. Time‐course studies indicate that initial apoptotic events are inhibition of proteasome activity, concomitant with an increased endoplasmic reticulum (ER) stress apoptotic signaling, and a consistent Noxa protein up‐regulation. These events precede, and some of them contribute to, mitochondrial alterations, which occur notwithstanding Mcl‐1 accumulation induced by GSI I. In CLL cells, GSI I inhibits Notch1 and Notch2 activation only in the late apoptotic phases, suggesting that this event does not initiate CLL cell apoptosis. However, Notch inhibition may contribute to amplify GSI I‐induced CLL cell apoptosis, given that Notch activation sustains the survival of these cells, as demonstrated by the evidence that both Notch1 and Notch2 down‐regulation by small‐interfering RNA accelerates spontaneous CLL cell apoptosis. Overall, our results show that GSI I triggers CLL cell apoptosis by inhibiting proteasome activity and enhancing ER stress, and amplifies it by blocking Notch activation. These findings suggest the potential relevance of simultaneously targeting these three important apoptosis regulators as a novel therapeutic strategy for CLL.     

Relationship between clonogenic radiosensitivity, radiation-induced apoptosis and DNA damage/repair in human colon cancer cells

The intrinsic radiation sensitivity of normal and tumour tissue is a major determinant of the outcome of radiotherapy. There is currently no established test that can be used routinely to measure the radiosensitivity of the cells in an individual patient's cancer in a manner that can inform treatment planning. The purpose of this study was to evaluate, in four human colorectal adenocarcinoma cell lines, two possible end points as surrogate markers of radiation response--apoptosis and induction of DNA single-strand breaks--and to compare the results with those of a conventional clonogenic assay. Cell lines (SW707 SW480, SW48 and HT29) known to differ in radiosensitivity were exposed to single doses of X-rays ranging from 0.5 to 5 Gy and cell survival was measured using the clonogenic assay. Apoptosis was determined on the basis of morphology under fluorescent microscopy and DNA damage/repair was measured, as tail moment, using an adaptation of the alkaline comet assay. The relationship between surviving fraction at 2 Gy (SF2) and the percentage of apoptotic cells 24 h after the same dose was complex, but apoptosis accurately predicted the order of radiosensitivities as measured by SF2. Initial damage measured after 2 Gy using the alkaline comet assay gave a close correlation with SF2 (r2=0.95), whereas there was no correlation between initial DNA damage repair rate and SF2.     

表皮生长因子受体3在结肠癌中的表达及其与结肠癌细胞增殖凋亡的关系研究

目的：研究表皮生长因子受体3（Her3）基因在人结肠癌中的表达,分析其与结肠癌细胞增殖凋亡的关系。方法利用实时定量PCR及免疫组织化学检测人结肠癌组织中Her3基因的表达,利用siRNA技术下调结肠癌细胞系中Her3的表达,利用体外细胞模型分析相关机制。结果 Her3基因及蛋白在人结肠癌组织中的水平较正常组织显著增高;Her3的表达与AKT信号的激活呈正相关。体外研究表明,随着Her3基因的表达下调,结肠癌细胞株SW480及Lovo的增殖显著下降,凋亡显著增加;且Her3表达下调后,AKT及MAPK的激活显著下降。结论 Her3基因在人结肠癌中高表达,且与结肠癌细胞增殖、凋亡相关,其机制可能是Her3增强了表皮生长因子的信号传导。