葛仙米提取物诱导肝癌细胞HepG2凋亡的活性研究

[目的]研究葛仙米提取物诱导肝癌细胞HepG2凋亡的活性。[方法]采用二甲基四氮唑蓝（MTT）法测定细胞存活率,形态学法观察凋亡的特征性变化,AnnexinV/PI双染及PI单染流式细胞术法检测凋亡率。[结果]经不同浓度提取物作用后,HepG2细胞的生长受到显著抑制,并呈现时间-浓度依赖关系趋势。观察细胞形态,发现有凋亡特征性变化。AnnexinV/PI双染结果显示,癌细胞早期凋亡率随提取物浓度的升高而显著增高,最高可达79.2%。PI法同样显示凋亡的发生,其凋亡峰最大比率为9.6%,显著高于对照组。[结论]葛仙米甲醇提取物能够诱导肝癌细胞HepG2的凋亡。     

试验用和临床用紫杉醇诱导肝癌细胞凋亡的比较

[目的]为了探讨试验用和临床用紫杉醇对肝癌HepG2细胞凋亡诱导作用的差异。[方法]用不同浓度的试验用和临床用紫杉醇处理肝癌HepG2培养细胞后,通过显微观察和流式细胞术检测其细胞凋亡。[结果]临床用紫杉醇在终浓度为0.5、1.0和2.0 mg/ml时,24 h非常显著性诱导细胞凋亡,48 h诱导细胞凋亡更剧烈。试验用紫杉醇24 h在终浓度为2.5、5.0和10.0 mg/ml时,非常显著诱导细胞凋亡;当试验用紫杉醇浓度为2.5 mg/ml时,48 h诱导细胞凋亡更剧烈。当试验用紫杉醇浓度为5和10 mg/ml细胞凋亡率逐步变低,可能走向死亡。[结论]在诱导肝癌细胞凋亡中,试验用紫杉醇要比临床所用紫杉醇的浓度要高。     

构树黄酮诱导肝癌细胞凋亡的初步观察

[目的]研究构树黄酮对肿瘤细胞的抑制效果。[方法]将处于对数生长期的Hep G2细胞接种于含有0、25、50、100、200、300μg/ml构树黄酮的DMEM培养基中,在37℃、5%CO2条件下分别培养24、48和72 h,采用MTT法测定构树黄酮对Hep G2细胞增殖的影响、用碘化丙啶(PI)染色法观察细胞形态的变化,并计算Hep G2细胞凋亡率。[结果]构树黄酮能显著抑制Hep G2细胞增殖,并呈现剂量和时间依赖性;构树黄酮能诱导Hep G2细胞凋亡,其最低有效浓度为25μg/ml;且Hep G2细胞凋亡率呈随着构树黄酮浓度增加及作用时间延长而升高。[结论]构树黄酮能抑制Hep G2细胞增殖并诱导其凋亡。     

川芎嗪逆转人鼻咽癌顺铂耐药细胞系多药耐药性的实验研究

目的探讨川芎嗪（TMP）对人鼻咽癌顺铂（DDP）耐药细胞系（CNE2/DDP）多药耐药性的逆转作用。方法 TMP处理CNE2/DDP细胞后,分别用MTT法、流式细胞术、RT-PCR检测其对DDP耐药性的逆转作用、细胞凋亡和bcl-2mRNA表达的影响。结果 50、100mg/LTMP处理后,CNE2/DDP细胞对DDP耐药性的相对逆转率分别为57.50%、85.72%,差异有统计学意义（P〈0.01）。与对照组比较,50mg/LTMP处理可使CNE2/DDP细胞凋亡率明显增高（P〈0.01）,而bcl-2mRNA表达明显降低（P〈0.05）。结论 TMP可部分逆转CNE2/DDP细胞对DDP的耐药性。TMP可增强DDP对CNE2/DDP细胞的促凋亡作用,下调bcl-2mRNA表达。     

姬松茸多糖诱导HepG2 细胞凋亡的线粒体通路研究

为探讨姬松茸多糖诱导HepG2细胞凋亡过程中线粒体膜电位和细胞内Ca2+浓度([Ca2+]i)的变化.以人肝癌细胞系HepG2细胞为对象,使用流式细胞仪检测姬松茸多糖对HepG2细胞凋亡及线粒体膜电位的影响,激光共聚焦显微镜检测HepG2细胞[Ca2+]i的变化.结果表明姬松茸多糖能显著诱导HePG2细胞凋亡,并不同程度降低HepG2细胞线粒体跨膜电位,升高细胞[Ca2+]i,造成钙稳态失衡.姬松茸多糖诱导HepG2细胞凋亡的机制与降低线粒体膜电位,造成细胞内Ca2+超载有关.     

2-辛亚砜-5,8-二甲氧基-1,4萘醌通过ROS/Akt通路诱导HepG2细胞凋亡

为研究修饰后的萘醌类衍生物对人肝癌细胞株HepG2诱导细胞凋亡作用及其机制。采用MTT、流式和Western blot方法观察2-辛亚砜-5,8-二甲氧基-1,4萘醌对人肝癌细胞的生长作用。结果表明:2-辛亚砜-5,8-二甲氧基-1,4萘醌可通过促进早期ROS水平升高,抑制Akt的磷酸化水平,并选择性地激活p38,ERK信号通路,从而抑制肝癌细胞株HepG2细胞的增殖并诱导其发生凋亡。     

犬细小病毒通过促进ROS产生/线粒体损伤诱导宿主细胞的凋亡

为探讨犬细小病毒(CPV)引起宿主细胞凋亡的分子机制,用CPV感染MDCK细胞,感染后通过台盼蓝染色法检测不同时间的细胞存活率,用Annexin V-FITC/PI法检测磷脂酰丝氨酸外翻情况,用试剂盒检测Caspase-3活性,分析CPV诱导细胞的凋亡。并通过流式细胞术检测细胞线粒体的损伤和ROS的产生探讨其分子机制。结果显示,随着病毒感染时间的不断延长,CPV可明显降低MDCK细胞存活率,促进磷脂酰丝氨酸外翻,增强Caspase-3活性,表明CPV可引起细胞凋亡。同时还发现CPV可明显提高细胞内ROS的水平,引起线粒体的损伤,这可能是CPV诱导细胞凋亡的重要分子基础。由此可见,CPV诱导MDCK细胞凋亡与CPV增加细胞ROS的产生和线粒体的损伤有关。     

猪源沙门氏菌多药外排泵oqx AB和氟苯尼考耐药基因floR的检测分析

用微量肉汤稀释法测定了215株猪源沙门氏菌对4种抗菌药物的敏感性,用PCR方法测定了多药外排泵基因oqxA、oqxB和氟苯尼考耐药基因floR,并用ERIC-PCR方法分析了猪源沙门氏菌菌株之间的相关性和遗传关系。结果显示:分离菌株对喹乙醇、痢菌净、氟苯尼考和恩诺沙星的耐药率分别为32.56%、20.93%、92.56%、16.74%;有152株菌同时携带oqxA和oqxB,另有7株菌单独携带oqxB;有156株菌携带floR基因; oqxA或oqxB阳性菌株可分为A～Q 17个ERIC型,oqxA和oqxB基因分布于不同的ERIC型菌株中。     

绿茶多酚诱导肝癌细胞凋亡时Caspase-3蛋白活性与mRNA的变化

[目的]研究绿茶多酚(EGCG)诱导肝癌细胞Hep-G2凋亡过程中半胱天冬酶-3(Caspase-3)蛋白活性与mRNA的变化。[方法]100 mg/L的EGCG处理Hep-G2细胞48 h,DAPI染色观察细胞形态学,用MTT检测EGCG对Hep-G2细胞生长的影响,流式细胞技术Annexin V-FITC PI法检测不同浓度EGCG诱导细胞的凋亡率,分光光度法检测Caspase-3的活性,用半定量RT-PCR法检测Caspase-3的mRNA变化。[结果]100 mg/L的EGCG作用Hep-G2细胞48 h后,荧光显微镜观察到细胞出现核碎裂和凋亡小体;MTT法检测到EGCG对肝癌细胞Hep-G2的生长均有显著抑制作用,呈浓度依赖性;Annexin V-FITC PI法检测到不同浓度的EGCG作用与肝癌细胞Hep-G2后,凋亡率较对照组明显升高,并随诱导浓度的增加而增加;不同浓度的EGCG处理组和不同时间EGCG处理组的Caspase-3活性和mRNA表达量均比对照组明显升高。[结论]Caspase-3蛋白活性与mRNA上调是EGCG诱导肝癌细胞凋亡的的重要原因和机制。     

愈痫灵方对难治性癫痫大鼠多药耐药相关蛋白MRP1、P-gp、LAP、MCP-1表达的作用

目的 探讨“愈痫灵”方对红藻氨酸（KA）致痫难治性癫痫模型大鼠海马及颞叶皮质区多药耐药相关蛋白1（MRP₁）、P糖蛋白（P-gp）、层黏连蛋白（LAP）以及单核细胞趋化蛋白1（MCP-1）表达的影响。方法 （1）造模：在脑立体定位仪引导下,海马区微量进样器注入KA1.0μL（即1.0μg）点燃发作,选取发作行为级别在Racines标准Ⅳ级以上者,以丙戊酸钠及卡马西平灌胃干预14 d后,再次以亚惊厥剂量KA0.5μL复燃,筛选再次发作级别在Ⅳ级以上或持续状态大鼠,且脑电图检测有癫痫样波放电者为造模成功的耐药难治性癫痫模型鼠。（2）分组与处理：造模成功鼠随机分为愈痫灵方干预组、拉莫三嗪对照组、模型组,另设假手术对照组、空白对照组共5组,分别给予“愈痫灵”汤剂、拉莫三嗪及同等体积的蒸馏水（2 mL/d）灌胃30 d。（3）标本处置与检测：采用免疫组织化学技术,检测多药耐药相关蛋白MRP₁、P-gp、LAP、MCP-1在海马与颞叶皮层的表达。结果 与假手术对照组、空白对照组间比较,造模成功组海马区及颞叶皮质区MRP₁、P-gp、LAP、MCP-1的表达均明显升高,差异有统计学意义（P<0.01）;与模型组比较,愈痫灵、拉莫三嗪干预处理后能显著降低模型鼠海马区MRP₁、P-gp表达水平（P<0.05）,海马区及颞叶皮质区LAP、MCP-1的表达差异均无统计学意义（P>0.05）;愈痫灵方组与拉莫三嗪组比较,差异均无统计学意义（P>0.05）;各组间颞叶皮质区LAP、MCP-1表达差异无统计学意义（P>0.05）。结论 耐药性癫痫大鼠模型海马及颞叶皮质区多药耐药相关蛋白MRP₁、P-gp、LAP、MCP-1表达均明显升高,逆转与降低海马区MRP₁、P-gp的表达可能是“愈痫灵”方抗耐药性癫痫作用机制之一。     

Amplification and expression of genes associated with multidrug resistance in mammalian cells

In multidrug resistance, which is observed clinically and in tissue culture, cells that are challenged with certain cytotoxic drugs develop resistance not only to the selective agent but also to other, seemingly unrelated, agents. The multidrug-resistant phenotype is associated with DNA sequence amplification and with the overproduction of a number of cytosolic and membrane glycoproteins. The differential amplification and altered expression of at least two related genes, termed multidrug-resistant associated genes has been shown in multidrug-resistant Chinese hamster cells. In multidrug-resistant mouse and human cells, genes homologous to those in Chinese hamster cells are also amplified. The level of expression of these genes varied and did not correlate with their copy number. Furthermore, in Chinese hamster cells, the development of resistance to a single drug and multidrug resistance were closely related, but uncoupled, events. The overexpression of the multidrug-resistant genes was better correlated with the degree of resistance to the selective agent than it was with the extent of multidrug resistance.     

白术多糖对环磷酰胺致雏鸡肝脏细胞凋亡中线粒体通路的影响

试验旨在从线粒体介导的细胞凋亡通路,探讨白术多糖(PAMK)对环磷酰胺(CTX)诱导的雏鸡肝脏损伤的影响。试验选取1日龄岭南黄鸡240羽,随机分成4组:对照(Control)、环磷酰胺(CTX)、白术多糖(PAMK)以及白术多糖环磷酰胺联合组(PAMK+CTX)。试验结束后,采集雏鸡肝脏组织,用于形态学观察及线粒体介导的细胞凋亡通路相关基因mRNA表达量和蛋白表达水平检测。光镜结果显示,环磷酰胺诱导雏鸡肝脏组织细胞形态结构不完整、肝细胞索排列紊乱、空泡化。电镜结果显示,环磷酰胺可导致雏鸡肝脏组织细胞线粒体明显受损,并发生细胞凋亡。从分子水平探讨线粒体介导的细胞凋亡通路结果显示,环磷酰胺可导致雏鸡肝脏组织中促凋亡基因Caspase-3、Caspase-8、Caspase-9、Bax和p53 mRNA表达量显著升高(P0.05),抑凋亡基因Bcl-2mRNA表达量显著降低(P0.05)。白术多糖环磷酰胺联合组雏鸡肝脏组织中Caspase-3、Caspase-8、Bax的mRNA表达量显著降低(P0.05),Bcl-2 mRNA表达量显著升高(P0.05)。此外,白术多糖环磷酰胺联合组雏鸡肝脏组织中Caspase-3蛋白表达水平显著降低(P0.05),Bcl-2蛋白表达水平显著升高(P0.05)。研究结果表明,环磷酰胺可诱导雏鸡肝细胞凋亡,白术多糖可通过调节线粒体通路相关基因表达抵抗环磷酰胺诱导雏鸡肝细胞凋亡,对雏鸡肝脏产生保护作用。     

JA_1对体外培养肝癌细胞线粒体膜电位及wt-p53基因表达的影响

为探索梯度浓度的JA1对体外培养人肝癌细胞株(HCC-9724)的细胞周期、细胞线粒体膜电位和wt-p53蛋白表达的影响.采用流式细胞技术和体外细胞培养技术,发现经JA1处理后的细胞培养样本中有明显的DNA低含量颗粒("亚G1期"峰),细胞周期各时相分布发生改变,细胞在G1被阻滞.细胞线粒体膜电位(ΔΨm)明显下降,且表现出剂量和时间效应关系.而wt-p53蛋白阳性细胞百分率则随时间延长而逐渐增加.JA1诱导了HCC-9724细胞线粒体膜电位的下降和细胞凋亡,而wt-p53蛋白表达的增强则是其诱导HCC-9724细胞凋亡的重要分子机制之一.     

番茄红素通过下调异柠檬酸脱氢酶1诱导胃癌细胞凋亡

目的 探究番茄红素对胃癌细胞增殖和凋亡的影响及其可能机制.方法 不同剂量番茄红素处理胃癌细胞株SGC-7901、MGC-803,用MTT法检测细胞增殖,Hoechst 33258染色、流式细胞仪检测细胞凋亡、线粒体膜电位(MMP)、活性氧(ROS),免疫印迹检测异柠檬酸脱氢酶1(IDH1)、IDH2蛋白表达.结果 番茄红素呈剂量依赖性抑制SGC-7901、MGC-803细胞增殖.大于25 μmol/L番茄红素诱导SGC-7901细胞凋亡,增加ROS水平;50 μmol/L番茄红素降低MMP,下调IDH1蛋白表达(P＜0.01或0.05).结论 番茄红素可抑制胃癌细胞增殖、诱导凋亡;促凋亡机制可能是通过下调IDH1,阻断细胞ATP生成和提高细胞内ROS.     

巴西菇多糖对肝癌细胞株凋亡的影响及其机制

目的：研究巴西菇多糖诱导人肝癌细胞株(SMMC—7721)凋亡的作用及机制。方法：采用电镜、DNA电泳、免疫组化法，对SMMC—772l株细胞凋亡以及凋亡抑制基因bcl—2的表达进行检测。结果：SMMC—772l株细胞经巴西菇多糖处理后出现核固缩、膜起泡、凋亡小体形成．琼脂糖凝胶电泳呈现出典型凋亡DNA梯状带．细胞内bcl—2表达较对照组低。结论：巴西菇多糖能诱导SMMC—772l株细胞发生典型凋亡．其抑制细胞内bcl—2的表达，是诱发肿瘤细胞凋亡的机制之一。     

Cell surface P-glycoprotein associated with multidrug resistance in mammalian cell lines

The plasma membranes of hamster, mouse, and human tumor cell lines that display multiple resistance to drugs were examined by gel electrophoresis and immunoblotting. In every case, increased expression of a 170,000-dalton surface antigen was found to be correlated with multidrug resistance. This membrane component is of identical molecular size and shares some immunogenic homology with the previously characterized P-glycoprotein of colchicine-resistant Chinese hamster ovary cells. This finding may have application to cancer therapy.     

Requirement for caspase-2 in stress-induced apoptosis before mitochondrial permeabilization

A current view is that cytotoxic stress, such as DNA damage, induces apoptosis by regulating the permeability of mitochondria. Mitochondria sequester several proteins that, if released, kill by activating caspases, the proteases that disassemble the cell. Cytokines activate caspases in a different way, by assembling receptor complexes that activate caspases directly; in this case, the subsequent mitochondrial permeabilization accelerates cell disassembly by amplifying caspase activity. We found that cytotoxic stress causes activation of caspase-2, and that this caspase is required for the permeabilization of mitochondria. Therefore, we argue that cytokine-induced and stress-induced apoptosis act through conceptually similar pathways in which mitochondria are amplifiers of caspase activity rather than initiators of caspase activation.     

Role of the glutathione redox cycle in acquired and de novo multidrug resistance

Drug resistance represents a major obstacle to successful cancer chemotherapy. However, the specific biochemical mechanisms responsible for clinical drug resistance are unknown. In these studies resistance to the antitumor agent adriamycin was found to involve two mechanisms, one that decreased drug accumulation by the P170 mechanism and another that altered the glutathione redox cycle, an important pathway in the detoxification of reactive oxygen. This dual mechanism of drug resistance was demonstrated in cell lines that had acquired the multidrug-resistant phenotype and in human colorectal cancer cells with de novo resistance. These studies support a model of acquired and de novo multidrug resistance that includes alterations in both drug accumulation and the glutathione redox cycle.     

Hypoxic coordinate regulation of mitochondrial enzymes in mammalian cells

The effect of hypoxic exposure on various mitochondrial enzymes and on cell mitochondrial genomic content was studied in two types of mammalian cells. Hypoxia depressed the activity of six enzymes to the same degree. The kinetics of depression and of recovery during reexposure to normoxia were statistically similar for three marker enzymes. Despite the global and symmetrical decrease in enzyme activities, mitochondrial DNA remained constant. This suggests either symmetrical loss of mitochondrial enzymes from all mitochondria or complete loss of enzymes from a subpopulation of mitochondria with retention of an intact mitochondrial genome.