茶多酚对H2O2诱导HL—60细胞癌基因表达的影响

目的：观察茶多酚对H2O2诱导HL－60细胞癌基因表达的影响，同时观察细胞DNA片段化程度的变化，方法：用二苯胺法对小片段DNA进行分析，流式细胞仪观察癌基因表达变化。结果：H2O打断DNA的能力与其作用浓度及时间有关。H2O2可使细胞c-fos,c-jun,c-myc,bcl-2,p53表达发生变化，茶多酚可以影响H2O2诱导的DNA损伤及癌基因表达。结论：茶多酚在一定浓度下，可以抑制H2O2诱导的DNA氧化损伤，并抑制癌基因表达的变化，高学茶多酚可以增强H2O2的效应。     

黄芪总黄酮和黄芪甲苷对H_2O_2诱导的MRC-5细胞氧化损伤的保护作用

目的探讨黄芪总黄酮(AF)和黄芪甲苷(Astr)对硫氧还蛋白(Trx)和无嘌呤/无嘧啶核酸内切酶/氧化还原因子-1(APE/Ref-1)的表达影响及作用机制。方法将培养的细胞随机分为对照组、H2O2组、AF+H2O2组和Astr+H2O2组。H2O2作用于MRC-5细胞建立细胞氧化损伤模型;MTT法观察细胞活力,免疫荧光检测8-OHdG的表达,确定MRC-5细胞氧化损伤情况;流式细胞仪测定细胞凋亡;RT-PCR和Western印迹法检测APE/Ref-1、Trx mRNA和蛋白的表达。结果 800μmol/L H2O2孵育细胞24 h可显著诱导MRC-5细胞损伤,使细胞存活力下降至47.25%,细胞经AF和Astr与H2O2共孵育后,明显抑制由H2O2引起的APE/Ref-1蛋白表达下调,上调Trx的表达,降低了8-OHdG含量,抑制了氧化环境下的MRC-5细胞凋亡,细胞存活率明显升高。结论 Astr和AF通过上调APE/Ref-1和Trx的基因表达水平、拮抗H2O2而对MRC-5的氧化损伤具有保护作用。两者相比Astr优于AF。     

冬凌草甲素诱导人胰腺癌SW1900细胞DNA损伤及对H2AX蛋白表达的影响

目的 研究冬凌草甲素(ORI)诱导胰腺癌SW1900细胞DNA损伤对磷酸化组蛋白(H2AX)表达的影响.方法 彗星实验检测ORI诱导胰腺癌SW1900细胞DNA损伤的程度.Western印迹检测不同浓度ORI作用胰腺癌SW1900细胞后H2AX蛋白的磷酸化.免疫荧光实验检测Phos-S1981 ATM和γ-H2AX焦点.结果 彗星实验结果表明不同浓度的ORI(20,40,80μmol/L)处理SW1900细胞48 h后,可发生DNA损伤,并且随浓度增加,DNA损伤加重.Western印迹检测不同浓度ORI作用胰腺癌SW1900细胞后,H2AX蛋白发生磷酸化,γ-H2AX随着浓度增加表达增大.免疫荧光实验发现Phos-S1981 ATM和γ-H2AX焦点随着浓度增加表达量增加.结论 ORI可以诱导胰腺癌SW1900细胞DNA损伤;H2AX蛋白发生磷酸化,具体DNA损伤信号通路有待进一步研究.     

钙非依赖型磷脂酶A2对过氧化氢诱导胰岛微血管内皮细胞凋亡的影响

目的用过氧化氢（H2O2）诱导大鼠胰岛微血管内皮细胞（IMECs）凋亡，观察钙非依赖型磷脂酶A2（iPLA2）对其凋亡的影响。方法siRNA技术抑制IMECs iPLA2表达，DNA ladder法检测H2O2诱导后的DNA片段，Annexin V—FITC／PI双染色检测细胞凋亡率，DIOCs（3）染色检测细胞线粒体膜电位。结果（1）siRNA—iPLA2可明显抑制IMECs内iPLA2 mRNA的表达。（2）H2O2诱导后细胞DNA片段化程度随诱导时间的增加而增多，抑制iPLA2表达后细胞的梯状条带明显增亮。（3）干扰组和未干扰组、干扰阴性对照组相比凋亡率明显升高（P均〈0．01）。（4）与未干扰组比较，干扰组细胞线粒体膜电位明显下降（P〈O．01）。结论抑制iPLA2表达可促进H2O2诱导的IMECs凋亡。     

氯通道ClC-3反义寡核苷酸对过氧化氢诱导的大鼠主动脉平滑肌细胞凋亡的影响

目的研究ClC3反义寡核苷酸对H2O2诱导的大鼠主动脉平滑肌细胞凋亡的影响。方法蛋白免疫印迹法检测ClC3蛋白表达;形态学方法、DNA琼脂糖电泳、MTT法和流式细胞仪观察和分析H2O2诱导的大鼠主动脉平滑肌细胞形态学改变、DNA断裂、细胞存活率和凋亡率及ClC3反义寡核苷酸转染对其影响。结果ClC3反义寡核苷酸转染抑制内源性ClC3蛋白表达后,可加重H2O2诱导大鼠主动脉平滑肌细胞形态学改变及DNA断裂,细胞凋亡率由52.8%±13.6%增至75.7%±5.8%(n=6,P<0.01),而细胞存活率由48.9%±4.3%进一步降低为31.3%±4.3%(n=6,P<0.01)。结论ClC3反义寡核苷酸转染促进H2O2诱导的大鼠主动脉平滑肌细胞凋亡。     

新型硫化氢供体8L通过上调NF-E2相关因子2的表达拮抗H2O2损伤H9c2心肌细胞

目的探讨新型硫化氢供体8L对氧化应激诱导心肌细胞损伤的保护作用及NF-E2相关因子2(Nrf2)有关的分子机制。方法用活性氧供体过氧化氢(H2O2)处理培养的大鼠H9c2心肌细胞,建立心肌细胞损伤的体外模型以模拟急性缺血再灌注诱导的心肌损伤;在H2O2处理前给予8L预处理观察其对心肌细胞的保护作用。为了明确Nrf2的作用,在H2O2处理或8L预处理前给予其选择性抑制剂鸦胆苦醇预处理。细胞计数试剂盒8比色法检测细胞存活率,试剂盒法检测乳酸脱氢酶(LDH)的释放,罗丹明123染色结合荧光照相术检测线粒体膜电位(MMP),Western Blot法检测核内Nrf2的表达。结果 H9c2心肌细胞经0~600μmol/L H2O2处理6 h可浓度依赖性地降低细胞存活率,且半数有效浓度约为400μmol/L。400μmol/L H2O2处理H9c2心肌细胞6 h可使LDH释放增加,MMP降低,并增加细胞核内Nrf2的表达(P均0.01)。在用400μmol/L H2O2处理前,先用50、100和200μmol/L 8L预处理1 h,可将细胞存活率从(52.6±4.3)%分别提高至(72.5±6.3)%、(83.1±5.2)%和(85.7±4.9)%。200μmol/L 8L预处理1 h还可明显抑制H2O2诱导的LDH释放(P0.01)及MMP受损(P0.05),但可易化H2O2诱导的Nrf2表达上调(P0.01)。另外,10μmol/L鸦胆苦醇预处理1 h不但可加重H2O2诱导的心肌细胞损伤(P0.01),还可拮抗8L的心肌细胞保护作用(P0.01)。结论硫化氢供体8L可减轻氧化应激诱导的H9c2心肌细胞损伤,其机制可能与上调Nrf2有关。     

虎杖苷通过激活Nrf2/HO-1信号抑制氧化应激诱导的心肌细胞损伤

目的研究过氧化氢(H2O2)诱导的H9c2细胞损伤模型中,虎杖苷对心肌细胞的保护作用及机制。方法建立H2O2诱导的H9c2细胞损伤模型,MTT检测细胞生存能力;Western印迹检测细胞蛋白表达;试剂盒检测细胞培养上清液中超氧化物歧化酶(SOD)及丙二醛(MDA)水平。结果MTT实验筛选药物剂量为100μmol/L;H2O2有效刺激剂量为100μmol/L;虎杖苷预处理抑制了H2O2诱导的细胞活性下降,抑制了H2O2诱导的细胞凋亡。虎杖苷促进了核因子E2相关因子(Nrf)2和血红素加氧酶(HO)-1蛋白的表达,降低了SOD的水平,同时使MDA水平升高。Nrf2抑制剂ML385与虎杖苷同时预处理后细胞凋亡得到抑制,同时Nrf2和HO-1蛋白的表达水平下降,SOD的水平升高而MDA水平下降。结论虎杖苷抑制H2O2诱导的H9c2细胞凋亡,其机制与激活Nrf2/HO-1信号通路有关。     

哈巴苷对H2O2诱导的大鼠心肌细胞H9c2氧化应激损伤的保护作用

目的探究哈巴苷(HG)对大鼠心肌细胞氧化应激损伤的作用。方法将H9c2细胞随机分为对照组(H9c2组)、哈巴苷组、H2O2组和H2O2+哈巴苷组,用H2O2处理细胞,复制氧化损伤模型。用哈巴苷(4μmoL)处理细胞,CCK8检测细胞增殖,Hoechst染色检测细胞凋亡,二氯荧光乙酰乙酸盐(DCF)法检测细胞内活性氧(ROS),根据试剂盒说明书检测上清液中超氧化物歧化酶(SOD)、丙二醛(MDA)和谷胱甘肽(GSH)浓度,Westernblot检测细胞凋亡相关蛋白Bcl-2、Bax、Caspase-3和Caspase-9的表达。结果与H9c2组比较,H2O2组心肌细胞增殖倍数明显降低,哈巴苷作用细胞4d后,H2O2+哈巴苷组心肌细胞增殖倍数明显高于H2O2组;同时,与H9c2组比较,H2O2组细胞凋亡率明显升高;与H2O2组比较,H2O2+哈巴苷组细胞凋亡率显著降低;H2O2还能显著诱导H9c2细胞Bax、Caspase-3和Caspase-9的表达,抑制Bcl-2表达;HG能显著减弱H2O2诱导Caspase-3和Caspase-9表达和抑制Bcl-2表达的作用;此外,H2O2组细胞内ROS活性及上清液中SOD和GSH浓度明显低于H9c2组,MDA浓度明显高于H9c2组,H2O2+哈巴苷组细胞内ROS活性及SOD和GSH浓度明显高于H2O2组,MDA浓度明显低于H2O2组。结论哈巴苷能通过抑制氧化应激抑制心肌细胞H9c2凋亡。     

茶多酚对H2O2致HL—60细胞氧化损伤时DNA中8—羟基鸟嘌呤含量的影响

目的 观察茶叶的主要成分茶多酚（Teapolyphenol,TP)对HL－60细胞DNA中8－羟在鸟嘌呤（8－oh-G)变化的影响。方法 利用气相色谱仪（GC／FID）、气质联用仪（CGC／MS－SIM）测定DNA8－羟基鸟嘌呤含量,同时观察细胞丙二醛（MDA）含量、还原型谷胱甘肽／氧化型谷胱甘肽（GSH／GSSG）比值变化。结果 TP作为抗氧化剂在一定的浓度范围可以减少DNA的氧化损伤产生8－羟基鸟嘌呤的含量,但当TP高达到一定浓度时反而增高8－羟基鸟嘌呤的含量。结论TP对细胞DNA氧化损伤有抑制和促进两方面作用,这与TP的浓度有关,即一定浓度时TP具抗氧化作用,而高浓度时具促进对氧化氢的氧化作用。     

肌肽对过氧化氢诱导PC12细胞损伤后NF-κB P65表达的影响

目的探讨L-肌肽对H2O2诱导PC12细胞(大鼠肾上腺嗜铬细胞瘤细胞)凋亡的保护机制。方法在H2O2诱导PC12细胞凋亡模型的基础上,加入肌肽作用于细胞,采用MTT比色法检测肌肽对PC12细胞的增殖抑制作用;RT-PCR法检测凋亡相关基因NF-κB P65 mRNA的表达变化;免疫组化SABC法检测凋亡相关蛋白Caspase-3和NF-κB P65的表达,流式细胞仪(FCM)检测细胞凋亡。结果不同浓度的肌肽对H2O2损伤的PC12细胞的存活率有显著的提高作用,20 mmol/L浓度时达最大值(P<0.05)。20 mmol/L的肌肽作用于PC12细胞可降低NF-κB P65的mR-NA表达,降低NF-κB P65蛋白的表达,流式细胞仪检测显示肌肽可抑制细胞的早期和晚期凋亡率。结论肌肽对H2O2损伤的PC12细胞有保护作用,机制可能是通过抑制NF-κB P65的表达来抑制PC12细胞的凋亡而实现的。     

Selenium has a protective role in caspase-3-dependent apoptosis induced by H2O2 in primary cultured pig thyrocytes

OBJECTIVE: Hydrogen peroxide (H2O2), necessary for thyroid hormonogenesis, is produced at the apical surface of the thyroid follicular epithelium. Excess H2O2 is potentially cytotoxic and may contribute to the development of hypothyroidism, e.g. in severe selenium deficiency. Yet it is unclear how H2O2 contributes to thyroid cell death. DESIGN AND METHODS: H2O2-induced apoptosis and necrosis were studied in primary cultured pig thyroid cells. Glutathione peroxidase (GPx) activity was altered by culture in low serum with or without selenite substitution. Apoptosis was evaluated by spectrofluorometric measurement of caspase-3-specific substrate cleavage, and by analysis of DNA fragmentation by agarose gel electrophoresis. Necrosis was detected by 51Cr release from prelabeled cells. RESULTS: Exogenous H2O2 dose-dependently (100-400 micromol/l) activated caspase-3 within 3-12 h, and DNA degradation was observed after 24 h. The potency of H2O2 to induce apoptosis was low compared with that of staurosporine, a strong proapoptotic agent. H2O2-treated cells with reduced GPx activity showed increased caspase-3 activation. Incubation of serum-starved cells with selenite (10-100 nmol/l) normalized the GPx activity and reduced the activation of caspase-3 by H2O2. High H2O2 concentrations (400-800 micromol/l) were required to obtain necrosis. The H2O2-induced necrosis was exaggerated by both low GPx activity and catalase inhibition. CONCLUSIONS: Cytotoxic effects of H2O2 on thyroid cells include caspase-3-dependent apoptosis that occurs at H2O2 concentrations insufficient to induce necrosis. Selenium deficiency aggravates the apoptotic response, probably due to impaired capacity of GPx to degrade H2O2.     

Antiapoptotic effect of calcitonin gene-related peptide on oxidative stress-induced injury in H9c2 cardiomyocytes via the RAMP1/CRLR complex

Calcitonin gene-related peptide (CGRP) plays an important role in the mediation of protective effects observed in situations such as ischemic preconditioning in rat hearts. In this study, we investigated in H9c2 rat cardiomyoblasts if the protective effect of CGRP could be linked to an inhibitory effect on the apoptotic pathway. We also determined the specificity of observed effects by treatment with adrenomedullin (ADM) in stress conditions generated by 100 microM hydrogen peroxide. Using MTT assays, we demonstrate that a pretreatment with CGRP decreases by half the loss of cell viability induced by H(2)O(2). CGRP inhibits phosphatidylserine externalization, caspase 3 activation and DNA fragmentation due to oxidative stress. Using RT-PCR, we observed an increase in Bcl-2 mRNA expression induced by CGRP treatment. Dot blotting experiments showed that, in stress conditions, Bcl-2 protein level decreases while Bax is increased. CGRP administration prior to stress prevents these effects. The three-receptor activity modifying protein (RAMP) isotypes were detected by RT-PCR in H9c2 cells and in left ventricle rat tissue, RAMP1 and RAMP3 being the most abundant in both cases. RAMP1 expression was upregulated by CGRP while RAMP3 mRNA level was decreased. Cell viability assessed by MTT indicates that, contrary to CGRP, pretreatment of stressed cells with ADM, a RAMP2 agonist, fails to protect them while treatment with CGRP(8-37) (a RAMP1 and 2 inhibitor) abolished CGRP protective effect. Taken together, these data suggest that CGRP has antiapoptotic properties through the RAMP1/CRLR complex. CGRP could be used to prevent apoptosis in an ischemia-reperfusion context.     

Specific COX-2 inhibitor NS398 induces apoptosis in human liver cancer cell line HepG2 through BCL-2

AIM: To evaluate the effects of NS-398, a cyclooxygenase-2 (COX-2) inhibitor, on the proliferation and apoptosis of HepG2 cells. METHODS: The effects of NS-398 on the proliferation of HepG2 cells were evaluated by MTT. DNA fragmentation gel analysis was used to analyze the apoptotic cells. DNA ploidy and apoptotic cell percentage were calculated by flow cytornetry. The expression of COX-2 and Bcl-2 mRNA was identified by competitive RT-PCR. Furthermore, expression level of Bcl-2 was detected using Western blot in HepG2 after treated with NS-398. RESULTS: NS-398 inhibited cell proliferation and induced apoptosis of HepG2 cells in a concentration-dependent manner. DNA ploidy analysis showed that S phase cells were significantly decreased with increase of NS-398 concentration. The quiescent GO/G1 phase was accumulated with decrease of Bcl-2 mRNA. Whereas NS-398 had no effect on the expression of COX-2 mRNA, and no correlations were found between COX-2 mRNA and HepG2 cell proliferation and apoptosis induced by NS-398 (r=0.056 and r=0.119, respectively). Bcl-2 protein level was inhibited after treated with NS-398. CONCLUSION: NS-398 significantly inhibits the proliferation and induces apoptosis of HepG2 cells. Mechanisms involved may be accumulation of quiescent GO/G1 phase and decrease of Bcl-2 expression.     

Comparison of the effect of hydroxyurea and methotrexate on DNA fragmentation at various reaction conditions.

Using the changes in DNA breakage as a marker of DNA damage, the direct action of hydroxyurea (HU) and methotrexate (MTX) on DNA was examined. The experimental design was to expose isolated DNA to HU and MTX alone or HU and MTX with accelerators of free radical reaction (H2O2, Fe..) and to determine DNA fragmentation assessed by electrophoresis. The results indicated that HU can damage DNA, but to demonstrate this ability it needs H2O2, Fe.. or prolonged incubation in solution. Unlike HU, MTX with H2O2 was ineffective; MTX with Fe.. at certain degree protected DNA against lesions induced by Fe.. alone. It is concluded that despite several common features of HU- and MTX-induced toxic side-effects in the cells suggesting interference of these drugs with free radical reactions, their direct effect on DNA under oxidizing conditions is quite different at least at the concentrations used by us.     

二苯乙烯苷对H2O2诱导的血管内皮细胞P选择素和E选择素表达的影响

目的研究二苯乙烯苷(TSG)对H2O2诱导损伤的人脐静脉内皮细胞P选择素和E选择素表达的影响。方法运用逆转录聚合酶链反应(RT-PCR)和酶联免疫吸附试验(ELISA)分别检测P选择素和E选择素的mRNA和蛋白表达。结果 200μmol/L的H2O2作用人脐静脉内皮细胞24 h,P选择素和E选择素的mRNA和蛋白表达水平均明显上调,与空白对照组比较,差异具有显著性(P<0.01),但TSG预处理人脐静脉内皮细胞4 h后再加200μmol/L H2O2作用24 h,H2O2诱导的内皮细胞P选择素和E选择素的mRNA和蛋白表达水平降低,与H2O2处理组比较,差异有显著性(P<0.05)。结论 TSG通过降低黏附分子P选择素和E选择素的表达可保护内皮细胞免受氧化应激损伤,影响动脉粥样硬化进程。     

过氧化氢体外诱导细粒棘球蚴原头节细胞Caspase-3表达及超微结构改变的影响

目的探讨过氧化氢(H2O2)体外诱导细粒棘球蚴原头节细胞凋亡、Caspase-3表达和细胞超微结构的影响。方法RPMI1640添加谷氨酰胺组即体外培养细粒棘球蚴原头节,用5mmol/L H2O2诱导8h,使其发生细胞凋亡。用原位末端脱氧核糖核苷酸转移酶标记技术(TUNEL法)检测原头节细胞凋亡情况,用过氧化物酶标记链霉卵白素(SP)染色半胱天冬氨酸蛋白酶-3(caspase-3)。在透射电镜下观察原头节细胞超微结构的变化。结果过氧化氢诱导原头节细胞凋亡细胞增加,caspase-3表达增加,电镜观察原头节细胞异染色质增加,部分细胞染色质异常浓缩呈现凋亡细胞征象。结论H2O2可诱导细粒棘球蚴原头节细胞凋亡,且caspase-3参与原头节细胞的凋亡。     

Low concentrations of ethanol induce apoptosis in human intestinal cells

Background: Increased systemic levels of endotoxin have been detected in human alcoholics and are thought to be derived from the gut. Although a ‘leaky gut’ is considered to be a necessary factor for alcohol‐induced endotoxemia followed by chronic liver injury, the effects of low concentrations of ethanol on intestinal epithelial cells have not been fully understood. The aim of this study was to evaluate intestinal epithelial cell death induced by acute, low concentrations of ethanol in an in vitro system. Methods: The human intestinal Caco‐2 cell line was incubated with 0%, 5%, 10% ethanol for up to 3?h. Phosphatidylserine (PS) externalization, caspase‐mediated cytokeratin 18 (CK18) cleavage, and DNA fragmentation were evaluated using flow cytometry. The caspase inhibitor zVAD‐fmk was used to test the role of caspases in ethanol‐induced cell death. Results: Treatment with 5% and 10% ethanol for 3?h led to a gradual increase in PS externalization. Caspase‐mediated CK18 was significantly enhanced as early as 1?h after 10% ethanol incubation, while DNA fragmentation was detected from 2?h onwards. Not only caspase activation but also both PS externalization and DNA fragmentation were completely prevented by pretreatment with the caspase inhibitor. Conclusions: Apoptotic cell death in confluent Caco‐2 cells was induced by acute and low concentrations of ethanol. These results suggest that clinically achievable doses of ethanol impair intestinal barrier function by induction of apoptosis in intestinal epithelial cells. This impairment of the barrier function would allow endotoxin to enter the circulation and evoke hepatic inflammation.     

Melatonin suppresses NO-induced apoptosis via induction of Bcl-2 expression in PGT-beta immortalized pineal cells

In the present study, we investigated whether melatonin would prevent nitric oxide (NO)-induced apoptotic death of PGT-beta immortalized pineal cells. To examine the protective effect of melatonin, cytotoxicity assay, DNA fragmentation analysis, caspase-3 activity assay, and Western blotting for caspase-3 and poly(ADP-ribose) polymerase (PARP) were performed. Treatment of cells with S-nitroso-N-acetylpenicillamine (SNAP), an NO donor, was shown to induce apoptotic cell death in a dose-dependent manner, and pretreatment with melatonin (0.1 mm) attenuated the occurrence of NO-induced apoptotic cell death. DNA fragmentation in response to NO was also arrested by melatonin. Caspase-3 activity induced by NO was decreased with melatonin treatment. Furthermore, the active fragments of caspase-3 and PARP were almost completely absent following exposure to melatonin. To elucidate the protective mechanisms of action of melatonin, Western blot analyses for Bcl-2 expression and cytochrome c release were carried out. Pretreatment with melatonin (0.1 mm) induced the expression of Bcl-2 and suppressed the release of cytochrome c into the cytosol, thereby arresting NO-induced apoptotic cell death. These results suggest that the antiapoptotic effect of melatonin is associated with induction of Bcl-2 expression in PGT-beta cells, which in turn blocks caspase-3 activation and inhibits cytochrome c release into the cytosol.     

丹参酮对过氧化氢致慢性乙型肝炎患者外周血淋巴细胞DNA损伤的影响

目的:观察丹参酮对过氧化氢致慢性乙型肝炎患者外周血淋巴细胞DNA损伤的影响.方法:利用快速、灵敏的检测细胞DNA损伤的单细胞凝胶电泳(SCGE)技术并结合IMI 1.0慧星分析软件,以"彗星"尾长、尾%DNA、尾惯量和尾矩来评价淋巴细胞DNA的损伤程度.结果:加入丹参酮后使过氧化氢致慢性乙肝患者外周血淋巴细胞的DNA经SCGE形成的"彗星"尾长、尾%DNA、尾惯量和尾矩值减小(P＜0.05).结论:丹参酮对过氧化氢致慢性乙型肝炎患者外周血淋巴细胞DNA损伤有一定的拮抗作用.