DNA双链断裂诱导的细胞损伤应答反应研究进展

DNA双链断裂(DSB)能通过级联激活细胞信号传导通路,启动DNA修复系统以保证遗传信息的完整。细胞对DSB的DNA损伤应答(DDR)系统是由感应器、传递器及下游效应器分子组成的。首先,感应器在感受到DSB的存在后,激活磷脂酰肌醇激酶相关激酶(PIKKs)家族成员,后者可使组蛋白H2AX磷酸化(γH2AX)。γH2AX被认为是DSB的标志,可聚集大量效应分子在DSB位点进行修复,在此过程中则引起细胞周期停滞,染色体结构改变,甚至细胞自噬或凋亡。本文将简单概述当前对DSB细胞应答系统的研究进展。     

异鼠李素通过下调Notch1通路抑制HepG2细胞的增殖并诱导其凋亡

目的 探究异鼠李素（Isorhamnetin,ISO）是否通过下调Notch1的表达来抑制肝癌HepG2细胞增殖并促进其凋亡。方法 使用细胞毒性实验噻唑蓝（MTT）法检测评估HepG2细胞存活率,并使用流式细胞仪分析细胞的凋亡水平。克隆形成实验反应不同异鼠李素浓度下HepG2细胞的增殖情况。采用Western blot测定P53、Bcl-2和Bax的表达情况。结果 处理ISO后,HepG2细胞的存活能力表现出明显的剂量和时间依赖性抑制。在ISO处理24 h后,HepG2细胞系中诱导了凋亡。ISO处理以及敲除Notch1蛋白后,上调抑癌基因P53的表达,上调细胞凋亡相关蛋白Bax的表达以及下调Bcl-2的表达。进一步实验发现,Notch1 siRNA可以增强ISO的抗肿瘤特性。结论ISO通过下调Notch1通路抑制肝细胞癌（HCC）细胞的增殖并促进其凋亡。     

青藤碱通过调控NF-kB信号通路抑制胰腺癌Capan-1细胞增殖并诱导细胞凋亡

目的 探讨青藤碱对胰腺癌Capan-1细胞增殖、凋亡的影响及机制。方法 CCK8法检测细胞活力,DAPI/TUNEL双染检测细胞凋亡,流式细胞术Annexin V-FITC/PI染色法检测细胞凋亡率,Western blotting检测cleaved caspase-3蛋白、细胞核NF-κB蛋白表达。结果 CCK8结果表明青藤碱抑制胰腺癌Capan-1细胞增殖,并具有时间、浓度依赖性;DAPI/TUNEL染色结果表明,在青藤碱作用下,胰腺癌Capan-1细胞凋亡增多;流式细胞术Annexin V-FITC/PI结果表明,在青藤碱作用下,胰腺癌Capan-1细胞凋亡率增高;Western blotting结果表明,在青藤碱作用下,胰腺癌Capan-1细胞cleaved caspase-3表达升高,细胞核NF-kB表达降低。TNF-α降低青藤碱对胰腺癌Capan-1细胞增殖抑制作用、凋亡诱导作用和cleaved caspase-3表达的上调作用。结论 青藤碱通过调控NF-kB信号通路抑制胰腺癌Capan-1细胞增殖并诱导细胞凋亡。     

紫杉醇诱导胃癌BGC-823和SGC-7901细胞凋亡作用的比较

目的研究胃癌BGC-823细胞和SGC-7901细胞对紫杉醇诱导凋亡的敏感性。方法用0．1～0．5μmol·L^-1紫杉醇作用于BGC-823和SGC-7901细胞,再用0．3μmol·L^-1紫杉醇对BGC-823和SGC-7901细胞分别作用0、6、12、24、36、48h,通过形态学观察及流式细胞术检测细胞凋亡率的变化。结果（1）紫杉醇对两种胃癌细胞均有明显诱导凋亡作用,且均呈时间依赖性及剂量依赖性;（2）中分化的SGC-7901细胞株对紫杉醇的敏感性明显高于低分化的BGC-823细胞株。结论不同分化程度的胃癌细胞株对紫杉醇的敏感性不同。     

凋亡抑制蛋白在TRAIL诱导胃癌细胞凋亡中的作用

目的探讨凋亡抑制蛋白(inhibitor of apoptosis pro-teins,IAP)在调节胃癌细胞对肿瘤坏死因子相关凋亡诱导配体(tumor necrosis factor-related apoptosis-inducing ligand,TRAIL)敏感性方面的作用。方法 PI染色流式细胞术检测细胞凋亡;Western blot检测caspase-3、PARP、XIAP、Survivin、cIAP1和cIAP2的表达。结果 TRAIL能诱导胃癌细胞凋亡,BGC-823细胞较SGC-7901细胞对TRAIL更敏感。caspase-3的活化及PARP的裂解在TRAIL作用早期即出现,且BGC-823细胞较SGC-7901细胞发生得更快。4种IAP蛋白在两株胃癌细胞中都组成性地高表达,Survivin和cIAP1在TRAIL处理前后无变化。而XIAP在BGC-823细胞中明显下降,在SGC-7901细胞中无改变。cIAP2在TRAIL作用后两株细胞中均有所降低。结论 TRAIL诱导胃癌细胞凋亡可能在活化的caspase-3水平受调控,XIAP能保护胃癌细胞免于凋亡。     

全合成Jaspine B诱导人乳腺癌MDA-MB-231细胞凋亡及DNA损伤

目的研究全合成Jaspine B对人乳腺癌MDA-MB-231细胞的增殖抑制及凋亡诱导作用,并探讨其对细胞DNA的损伤。方法酸性磷酸酶法(APA)检测细胞增殖,荧光显微镜、透射电镜(TEM)观察细胞形态结构,DNA琼脂糖凝胶电泳检测DNA片段化,流式细胞技术检测凋亡率及线粒体膜电位(ΔΨm),Western blot检测凋亡相关蛋白表达,单细胞凝胶电泳(SCGE)检测DNA损伤。结果Jaspine B抑制细胞增殖,24、48、72h IC50分别为2.61、1.07、0.77μmol·L-1,其作用在一定范围内呈浓度和时间依赖性;细胞发生凋亡形态改变,生化特征上出现DNA梯状改变;1.50μmol·L-1及3.00μmol·L-1Jaspine B作用24h,早期凋亡细胞率分别为7.60%及15.48%,相应浓度作用48h,早期凋亡细胞率分别增至21.48%及23.60%;Jaspine B可引起ΔΨm明显下降、Cyt C水平增加,促使Caspase-3酶原剪切活化;Jaspine B作用24h,细胞出现明显DNA损伤。结论全合成Jaspine B对人乳腺癌MDA-MB-231细胞抑制增殖、诱导凋亡并诱发DNA损伤,凋亡经由依赖胱天蛋白酶的内在途径发生。     

天麻素通过抑制细胞凋亡保护谷氨酸诱导的PC12细胞损伤

目的：研究天麻素（Gastrodin）对谷氨酸诱导的大鼠肾上腺嗜铬细胞瘤PC12细胞损伤的影响及可能机制。方法：以谷氨酸建立体外培养PC12细胞损伤模型并采用MTT比色法测定细胞存活率;AO/EB双染法经荧光显微镜观察细胞凋亡形态;采用流式细胞术检测细胞内活性氧含量以及Annexin V/PI染色后的细胞凋亡率;Western blot法检测细胞内Caspase-3蛋白表达。结果：天麻素可明显抑制谷氨酸诱导的PC12细胞凋亡,在0.1～10μmol/L剂量呈一定的量效关系;同时,天麻素可明显抑制谷氨酸引起的活性氧（ROS）的累积,降低谷氨酸诱导的活性Caspase-3蛋白的表达,降低PC12细胞的凋亡率,在0.1～10μmol/L剂量呈量效相关性。结论：在一定剂量范围内,天麻素对谷氨酸损伤的PC12细胞具有保护作用,其机制可能与减少ROS的生成,阻止氧化损伤的发生,抑制Caspase-3途径依赖的细胞凋亡相关。     

葛根素通过神经酰胺通路抑制UVB诱导的HaCaT细胞DNA损伤

研究葛根素(puerarin,PUE)对UVB诱导的HaCaT细胞DNA损伤的影响和作用机制。葛根素预处理细胞以30 mJ.cm2 UVB照射,24 h后以彗星电泳实验检测DNA损伤,薄层色谱法和气相色谱法检测神经酰胺,流式细胞术检测细胞内游离钙离子,Western blotting法检测p38蛋白磷酸化水平。结果显示,UVB模型组细胞DNA损伤、细胞内游离钙离子、神经酰胺、磷酸化p38蛋白显著增加;与UVB模型组相比,各葛根素预处理组的DNA损伤、细胞内游离钙离子、神经酰胺、磷酸化p38蛋白均减少。结果表明,葛根素首先抑制神经酰胺蓄积,阻止下游的细胞内钙离子升高和p38 MAPK通路激活,从而减轻UVB诱导的HaCaT细胞DNA损伤。     

Schizandra chinensis extracts induce apoptosis in human gastric cancer cells via JNK/p38 MAPK activation and the ROS-mediated/mitochondria-dependent pathway

Abstract

Context: Schizandra chinensis Baill (Magnoliaceae) fruit extract (SCE) is considered a traditional herbal medicine for the treatment and alleviation of various diseases. Gastric cancer is the second most common cause of cancer-related death worldwide, and the first most common in Korea.

Objectives: This study investigates the mechanism of SCE-induced apoptosis in AGS human gastric cancer cells.

Materials and methods: SCE concentrations from 100 to 400?µg/ml were used. Cell viabilities were determined using MTT assay. Members of the Bcl-2 family and Bax were detected by Western blotting. RT-PCR was performed to measure the expression level of the Fas/FasL pro-apoptotic genes.

Results: SCE inhibited the proliferation AGS cells for 24 or 72?h (inhibition by 3.1%?±?5.2% at 100?µg/ml and 87.3%?±?7.6% at 400?µg/ml at 24?h and by 40.2%?±?5.3% 100?µg/ml and 95.3%?±?1.3% 400?µg/ml at 72?h) and increased the sub-G1 phase (25.3%?±?5.2% at 100?µg/ml and 370.2%?±?7.2% at 400?µg/ml) and the mitochondrial membrane depolarization (11.2%?±?2.1% at 100?µg/ml and 311.5%?±?6.1% at 400?µg/ml). The SCE-induced apoptotic cell death showed the down-regulation of Bcl-2, but up-regulation of Bax. Subsequently, SCE increased the expression level of Fas/FasL, activated caspase-9 and -3, and increased reactive oxygen species generation. Also, JNK II inhibitor or a p38 MAPK inhibitor inhibited SCE-induced cell death.

Discussion and conclusion: These results indicate that SCE might be an effective chemotherapeutic for the treatment of human gastric cancer.     

Resveratrol induces gastric cancer cell apoptosis via reactive oxygen species, but independent of sirtuin1

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miR-144通过靶向TIGAR调控胃癌细胞增殖与凋亡及自噬的分子机制

目的研究miR-144对胃癌细胞增殖、凋亡和自噬的影响和机制。方法将miR-144 mimics、mimics control分别转染胃癌细胞,依次标记为mimics-NC组、miR-144 mimics组。将miR-144 mimics分别与pcDNA3.1、pcDNA3.1-TIGAR共转染至胃癌细胞,依次标记为miR-144 mimics+NC组、miR-144 mimics+TIGAR组。正常培养的胃癌细胞标记为Control组。以噻唑蓝法检测细胞增殖,以流式细胞术测定细胞凋亡,以Western blot检测凋亡蛋白caspase-3和自噬蛋白Beclin1、LC3Ⅱ/Ⅰ表达变化,以生物信息学软件预测miR-144的靶基因可能为TIGAR,利用荧光素酶报告系统鉴定靶向关系。结果 mimics-NC组和miR-144 mimics组的细胞增殖能力分别为0.36±0.05,0.20±0.02,细胞凋亡率分别为3.05±0.34,13.84±1.47,caspase-3表达水平分别为0.22±0.04,0.43±0.05, Beclin1分别为0.38±0.06,0.73±0.07,LC3Ⅱ分别为0.19±0.03,0.39±0.05,差异均有统计学意义(均P<0.05)。miR-144 mimics+NC组和miR-144 mimics+TIGAR组的细胞增殖能力分别为0.21±0.04,0.32±0.03,细胞凋亡率分别为12.04±1.25,5.98±0.73,caspase-3表达水平分别为0.40±0.03,0.24±0.05,Beclin1分别为0.60±0.05,0.46±0.06,LC3Ⅱ分别为0.34±0.06,0.20±0.03,差异均有统计学意义(均P<0.05)。结论 miR-144靶向抑制TIGAR表达降低胃癌细胞增殖能力,并诱导胃癌细胞凋亡和自噬。     

鱼腥草总黄酮调控PI3K/Akt信号通路诱导人乳腺癌细胞株MCF-7凋亡的实验研究

目的：探讨鱼腥草总黄酮调控磷脂酰肌醇3-激酶（PI3K）/蛋白激酶B（Akt）信号通路对人乳腺癌细胞株MCF-7凋亡的诱导作用。方法：取对数期MCF-7细胞,随机分为4组（5个复孔）,低、中、高剂量组分别用3,6,9 g·L^-1鱼腥草总黄酮处理,对照组用磷酸盐缓冲液（PBS）处理。干预48 h后进行细胞形态学观察;对比干预12,24,48 h时的细胞凋亡率;对比干预48 h时PI3K、Akt、B淋巴细胞瘤-2基因（Bcl-2）、Bcl-2相关X蛋白（Bax）mRNA和PI3K、Akt、磷酸化Akt（pAkt）、Bcl-2、Bax蛋白相对表达量。结果：Hoechst 33258染色结果显示,干预后3剂量组部分细胞体积缩小、染色质浓缩,出现凋亡小体,且中剂量组凋亡现象最为明显;细胞凋亡率、Bax mRNA和蛋白相对表达量组间比较,中剂量组最高、高剂量组其次、低剂量组其稍低、对照组最低,且每2组间比较差异均有显著性（P<0.05）;细胞凋亡率组内比较,对照组随时间的延长变化不显著（P>0.05）,3剂量组均随时间的延长显著增加（P<0.05）;PI3K、Bcl-2 mRNA和PI3K、pAkt、Bcl-2蛋白相对表达量组间比较,中剂量组最低、高剂量组其次、低剂量组稍高、对照组最高,且每2组间比较差异均有显著性（P<0.05）;Akt mRNA和蛋白相对表达量组间比较差异均不显著（P>0.05）。结论：鱼腥草总黄酮可促进人乳腺癌细胞株MCF-7的凋亡,其中浓度为6 g·L^-1时促凋亡作用最强,推测是通过下调PI3K、Bcl-2 mRNA和PI3K、pAkt、Bcl-2蛋白表达,上调Bax mRNA和蛋白的表达,与PI3K/Akt信号通路有关。     

氧化苦参碱通过下调miR-155-5p对胃癌细胞的增殖、凋亡、迁移、侵袭作用

目的 探讨氧化苦参碱通过调节miR-155-5p表达对胃癌细胞的增殖、凋亡、迁移、侵袭中的作用和其潜在机制。方法 使用TRIzol法提取组织标本和细胞系的总RNA,检测胃癌组织与癌旁组织中的miR-155-5p表达情况。采用qRT-PCR评估miR-155-5p在人胃癌细胞系（SGC7901、MGC803）与正常胃黏膜上皮（GES-1、AGS）细胞中的表达情况。将MGC803分为空白组、转染错义序列siRNA组、miR-155-5p模拟物组、miR-155-5p抑制剂组、氧化苦参碱（100 μmol/L）组、氧化苦参碱＋miR-155-5p模拟物组。采用MTT法观察不同干预下胃癌细胞的生长抑制作用,用细胞集落形成试验检测不同干预下胃癌细胞的增殖情况。用流式细胞技术分析不同干预对胃癌细胞凋亡的影响。Transwell法检测不同干预后胃癌细胞的迁移、侵袭情况。蛋白质印迹法检测MGC803细胞中Claudin 1、c-Myc、cyclin D1、Bcl-2、Caspase-3蛋白的相对表达量。结果 与癌旁组织和胃黏膜细胞（GES-1、AGS）相比,在胃癌组织和胃癌细胞系（SGC7901、MGC803）中miR-155-5p相对表达量升高（P＜0.001）。而氧化苦参碱通过调节miR-155-5p表达抑制胃癌细胞生长。MTT实验表明,miR-155-5p模拟物的转染后MGC803细胞活力显著增加,而氧化苦参碱可显著抑制胃癌细胞、转染和miR-155-5p模拟物的细胞活力（P＜0.001）。与空白组、错义序列siRNA组相比,miR-155-5p模拟物转染后MGC803细胞活力显著增加,细胞集落生成增加,而氧化苦参碱可显著抑制胃癌细胞的活力和转染miR-155-5p模拟物的细胞活力,及细胞集落生成数（P＜0.001）。miR-155-5p-模拟物组的细胞迁移和侵袭细胞数显著增加、凋亡比例降低,而氧化苦参碱组和miR-155-5p-抑制剂组细胞迁移和侵袭细胞数量降低、凋亡比例升高（P＜0.001）。miR-155-5p模拟组的Claudin 1、c-Myc、Cyclin D1、Bcl-2相对表达量增加,而Caspase-3相对表达量降低（P＜0.01、0.001）。而miR-155-5p抑制剂组、氧化苦参碱组和氧化苦参碱＋miR-155-5p抑制剂组的Claudin 1、c-Myc、Cyclin D1、Bcl-2表达较miR-155-5p模拟组显著下降,Caspase-3表达增加（P＜0.001）。结论 miR-155-5p可能是胃癌的治疗靶点,氧化苦参碱可通过miR-155-5p的调节作用发挥抗肿瘤作用。     

Ouabain induces apoptotic cell death in human prostate DU 145 cancer cells through DNA damage and TRAIL pathways

Ouabain, a cardiotonic steroid and specific Na⁺/K⁺‐ATPase inhibitor, has a potential to induce cancer cell apoptosis but the mechanisms of apoptosis induced by ouabain are not fully understand. The aim of this study was to investigate the cytotoxic effects of ouabain on human prostate cancer DU 145 cells in vitro. Cell morphological changes were examined by phase contrast microscopy. Cell viability, cell cycle distribution, cell apoptosis, DNA damage, the production of ROS and Ca²⁺, and mitochondrial membrane potential (ΔΨ_m) were measured by flow cytometry assay. Results indicated that ouabain induced cell morphological changes, decreased total cell viability, induced G0/G1 phase arrest, DNA damage, and cell apoptosis, increased ROS and Ca²⁺ production, but decreased the levels of ΔΨ_m in DU 145 cells. Ouabain also increased the activities of caspase‐3, ‐8, and ‐9. Western blotting was used for measuring the alterations of apoptosis‐associated protein expressions in DU 145 cells and results indicated that ouabain increased the expression of DNA damage associated proteins (pATM^Ser1981, p‐H2A.X^Ser139, and p‐p53^Ser15) and ER‐stress‐associated proteins (Grp78, ATF6β, p‐PERK^Thr981, PERK, eIF2A, GADD153, CaMKIIβ, and caspase‐4) in time‐dependently. Furthermore, ouabain increased apoptosis‐associated proteins (DR4, DR5, Fas, Fas Ligand, and FADD), TRAIL pathway, which related to extrinsic pathway, promoted the pro‐apoptotic protein Bax, increased apoptotic‐associated proteins, such as cytochrome c, AIF, Endo G, caspase‐3, ‐8, and ‐9, but reduced anti‐apoptotic protein Bcl‐2 and Bcl‐x in DU 145 cells. In conclusion, we may suggest that ouabain decreased cell viability and induced apoptotic cell death may via caspase‐dependent and mitochondria‐dependent pathways in human prostate cancer DU 145 cells.     

二烯丙基二硫对人胃癌MGC803细胞G_2/M期检查点Chk1与Chk2的影响

目的研究二烯丙基二硫(diallyl disulfide,DADS)对人胃癌MGC803细胞G2/M期检查点Chk1与Chk2的影响。方法流式细胞术检测细胞周期改变;Northern blot、Westernblot与免疫细胞化学检测DADS处理MGC803细胞的Chk1与Chk2表达。结果流式细胞术分析显示,30 mg.L-1DADS呈时间依赖性阻滞MGC803细胞在G2/M期(P<0.05);Northern blot检测表明,DADS不同时间作用MGC803细胞后,Chk1与Chk2 mRNA表达与未处理组差异无显著性(P>0.05);免疫细胞化学发现Chk1与Chk2表达与未处理组无明显改变(P>0.05);Western blot DADS在不同时间对MGC803细胞Chk1与Chk2总蛋白表达无改变(P>0.05),而磷酸化的Chk1表达呈时间依赖性增加(P<0.05),但磷酸化的Chk2无明显改变(P>0.05)。结论 DADS阻滞MGC803细胞G2/M期与磷酸化Chk1有关。     

4β‐Hydroxywithanolide E selectively induces oxidative DNA damage for selective killing of oral cancer cells

Reactive oxygen species (ROS) induction had been previously reported in 4β‐hydroxywithanolide (4βHWE)‐induced selective killing of oral cancer cells, but the mechanism involving ROS and the DNA damage effect remain unclear. This study explores the role of ROS and oxidative DNA damage of 4βHWE in the selective killing of oral cancer cells. Changes in cell viability, morphology, ROS, DNA double strand break (DSB) signaling (γH2AX foci in immunofluorescence and DSB signaling in western blotting), and oxidative DNA damage (8‐oxo‐2′deoxyguanosine [8‐oxodG]) were detected in 4βHWE‐treated oral cancer (Ca9‐22) and/or normal (HGF‐1) cells. 4βHWE decreased cell viability, changed cell morphology and induced ROS generation in oral cancer cells rather than oral normal cells, which were recovered by a free radical scavenger N‐acetylcysteine (NAC). For immunofluorescence, 4βHWE also accumulated more of the DSB marker, γH2AX foci, in oral cancer cells than in oral normal cells. For western blotting, DSB signaling proteins such as γH2AX and MRN complex (MRE11, RAD50, and NBS1) were overexpressed in 4βHWE‐treated oral cancer cells in different concentrations and treatment time. In the formamidopyrimidine‐DNA glycolyase (Fpg)‐based comet assay and 8‐oxodG‐based flow cytometry, the 8‐oxodG expressions were higher in 4βHWE‐treated oral cancer cells than in oral normal cells. All the 4βHWE‐induced DSB and oxidative DNA damage to oral cancer cells were recovered by NAC pretreatment. Taken together, the 4βHWE selectively induced DSB and oxidative DNA damage for the ROS‐mediated selective killing of oral cancer cells.