榄香烯衍生物诱导HeLa细胞凋亡的实验研究

目的研究榄香烯衍生物(榄香烯哌嗪)对人宫颈癌细胞HeLa体外增殖的抑制作用及其作用机制。方法采用SRB法考察榄香烯哌嗪对多种人癌细胞体外增殖的抑制作用。普通光学显微镜及荧光显微镜观察榄香烯哌嗪对HeLa细胞形态的影响,利用流式细胞仪检测HeLa细胞凋亡及细胞周期变化情况。结果榄香烯哌嗪对HeLa、HepG2、SGC-7901及Bel-7402细胞有较强的体外增殖抑制作用。光学显微镜和荧光显微镜观察榄香烯哌嗪10μmol.L-1处理的HeLa细胞,细胞体积变小、细胞核皱缩致密,可见凋亡小体。此外,榄香烯哌嗪可将HeLa细胞阻滞于G0/G1期,且随药物作用时间延长或剂量增加,DNA直方图上可见渐强的SubG1峰。结论榄香烯哌嗪可诱导人宫颈癌HeLa细胞凋亡,且具有细胞周期阻滞作用。     

葫芦素B纳米脂质载体对结肠癌和乳腺癌细胞抑制及凋亡作用的研究

目的：研究葫芦素B纳米脂质载体（CuB-NLC）对结肠癌Lovo细胞,乳腺癌MCF-7细胞的体外细胞毒性。方法：结肠癌Lovo细胞,乳腺癌MCF-7细胞常规复苏、培养及传代,取处于对数生长期的细胞用于实验。采用CCK-8法检测质量浓度为0、0.0625、0.25、1.00、4.00、16.0 mg/L的CuB-NLC对结肠癌Lovo细胞,乳腺癌MCF-7细胞的毒性,流式细胞仪检测结肠癌Lovo细胞,乳腺癌MCF-7细胞的细胞周期进程及Annexin V/PI双染法检测细胞的凋亡率。结果：与葫芦素B （CuB）相比CuB-NLC对结肠癌Lovo细胞,乳腺癌MCF-7细胞生长抑制作用明显增强（P＜0.05）,且这种抑制作用随药物浓度增加而增强。CuB组及CuB-NLC组作用于结肠癌Lovo细胞、乳腺癌MCF-7细胞48 h后,与NLC空白组及DMSO对照组相比较,CuB及CuB-NLC均能够引起结肠癌Lovo细胞、乳腺癌MCF-7细胞G2/M期阻滞,同时伴有G0/G1期细胞减少, CuB-NLC组的作用更加明显,有统计学差异（P＜0.05）。Annexin V/PI双染法检测结果表明,CuB-NLC能显著诱导结肠癌Lovo细胞,乳腺癌MCF-7细胞凋亡。结论：葫芦素B纳米脂质载体能够抑制结肠癌Lovo细胞,乳腺癌MCF-7细胞的增殖,诱导细胞凋亡。     

榄香烯对B细胞淋巴瘤Raji细胞株的体内外抑制作用

目的:探讨榄香烯对B细胞淋巴瘤Raji细胞株的体内外作用。方法:不同浓度的榄香烯体外作用Raji细胞不同时间,CCK-8法检测增殖抑制作用,Annexin V/PI双染色法检测细胞凋亡,DAPI染色进行细胞核形态学分析,PI单染色法检测细胞周期改变;动物实验观察榄香烯体内抑瘤作用。结果:榄香烯对Raji细胞生长具有明显的抑制作用,呈量效和时效关系;榄香烯能诱导Raji细胞凋亡,呈量效关系;DAPI染色显示榄香烯作用Raji细胞具有凋亡细胞核的特征性核形态;细胞周期分析显示G0/G1期细胞相对增多、S期和G2/M期细胞均相对减少;榄香烯明显抑制Raji细胞在SCID小鼠体内增殖。结论:榄香烯对Raji细胞具有明显的增殖抑制作用,其机制可能是通过G0/G1期阻滞导致细胞凋亡发挥效用的。     

槲皮素对肝癌HepG2细胞生长影响的体外研究

目的 观察槲皮素对肝癌HepG2细胞生长及hTERT基因表达的影响.方法 以台盼蓝拒染法计数肝癌细胞的生长抑制率,用透射电镜从形态变化方面了解凋亡的发生,流式细胞术检测细胞周期变化,Western-blot检测hTERT基因表达改变,PCR-TRAP法检测端粒酶活性.结果 槲皮素抑制肝癌HepG2细胞增殖的作用明显,且呈浓度和时间依赖性,槲皮素处理48 h后的半数抑药浓度（IC5o）为25.5μmol/L;形态学检测显示出了细胞凋亡的特征变化,经10-20 μm/L的槲皮素处理,肝癌HepG2细胞周期阻滞于G0/G1期,且HepG2细胞hTERT蛋白降低,端粒酶活性被抑制.结论 槲皮素能呈时间、剂量依赖性地抑制肝癌细胞的生长,能诱导HepG2细胞发生凋亡,其抑制增生与诱导凋亡的机制可能与下调hTERT基因表达、抑制端粒酶活性、破坏端粒稳定性有关.     

榄香烯诱导肺癌A549细胞凋亡作用的剂量和时间依赖性研究

目的探讨榄香烯对肺癌A549细胞的增殖抑制作用及其对细胞凋亡的影响。方法每批细胞按空白对照组和药物处理组随机分组,检测榄香烯对癌细胞的增殖抑制作用;采用流式细胞光度分析术(FCM)检测细胞凋亡率及细胞周期时相分布,同时进行细胞的形态学观察。结果榄香烯存在剂量依赖性和时间依赖性,榄香烯在48 h、72 h对A549细胞周期有明显影响;榄香烯可阻滞A549细胞于S期并诱导细胞凋亡,但细胞凋亡率并不完全与药物浓度成正相关。结论榄香烯对肿瘤细胞具有较强的增殖抑制作用,在一定药物浓度范围内,随药物浓度的增加榄香烯可使细胞凋亡率升高,但超过一定作用浓度,药物的细胞毒作用增强,细胞凋亡率则呈下降趋势。     

5-氟脲嘧啶诱导人结直肠癌Lovo细胞凋亡的分子机制

目的：研究5-氟脲嘧啶（5-FTU）对体外培养人结直肠癌Lovo细胞增殖的抑制作用及诱导凋亡的分子机制。方法：分别采用MTT法检测细胞活力．用光镜、电镜观察凋亡细胞的组织形态学和超微结构变化，流式细胞术（FCM）分析诱导细胞凋亡的细胞周期阻滞点，免疫组化SP法检测对Lovo细胞增殖核抗原（PCNA）及凋亡相关基因蛋白P53、Bax表达的影响。结果：5-FU能抑制Lovo细胞生长，光镜与电镜结果均显示凋亡细胞明显增多。FCM分析Lovo细胞经5-FU诱导后凋亡百分率显著增加，并具有剂量和时间的效应。免疫组化显示5-FU组细胞PCNA表达明显低于对照组、Bax表达明显升高（P〈0．01），而P53在诱导前后均无表达。结论：5-FU能抑制Lovo细胞增殖并通过诱导该细胞系凋亡发挥抗肿瘤效应，激活bax基因和G2／M期阻滞是其诱导Lovo细胞凋亡的重要机制。     

MEK信号通路活化在榄香烯致人源U87MG胶质瘤细胞增殖抑制及G0/G1细胞周期阻滞中的作用

目的探讨MKK3和MKK6在榄香烯致人U87MG胶质瘤细胞增殖抑制和细胞周期阻滞中的作用。方法以不同浓度榄香烯作用于人U87MG及U251胶质瘤细胞,应用噻唑蓝(MTT)法检测细胞活性。West-ern blot检测MEK信号通路中MKK3和MKK6的总蛋白及磷酸化蛋白含量。通过转染显性负突变质粒DN-MKK3和DN-MKK6,抑制MKK3和MKK6的活性。然后分别行MTT法和流式细胞术检测榄香烯对胶质瘤细胞的增殖抑制和细胞周期阻滞作用。结果榄香烯显著抑制了人胶质瘤细胞的增殖,呈时间和浓度依赖性,并可使细胞中MKK3和MKK6的磷酸化水平上调。抑制MKK3和MKK6的活性则可显著削弱榄香烯的抗胶质瘤增殖和G0/G1细胞周期阻滞作用。结论榄香烯可以通过将胶质瘤细胞的细胞周期阻滞于G0/G1期,进而有效地抑制肿瘤细胞增殖,且MKK3和MKK6信号通路的激活在其中发挥着不可或缺的作用。     

β-榄香烯对人肝癌细胞株的体外放射增敏作用

目的通过体外实验探讨β-榄香烯对人肝癌细胞株的放射增敏作用机制。方法用克隆形成法检测不同时间-浓度条件β-榄香烯和／或放射作用后的人肝癌细胞株存活分数，计算放射增敏率（SER）。用流式细胞仪分析不同时间-浓度条件下β-榄香烯对细胞周期和细胞凋亡的影响。结果10、100、1000nmoL／L β-榄香烯作用24h后SER分别为1．32，1．71和1．36。β-榄香烯作用时间和浓度越高，人肝癌细胞G2／M期的比率也越高。100、1000nmoL／L β-榄香烯作用24h后，G2／M期比率明显升高。10nmol β-榄香烯作用24h细胞凋亡百分率20．71％。结论β-榄香烯对人肝癌细胞有放射增敏作用，其作用机制可能与对诱导肝癌细胞凋亡和β-榄香烯对细胞的G2／M期阻滞有关。     

芹黄素对体外人大肠癌Lovo细胞生物学活性的影响及机制研究

目的探讨芹黄素对体外人大肠癌Lovo细胞生物学活性的影响及其可能的作用机制。方法不同浓度的芹黄素作用于体外培养的人大肠癌Lovo细胞24、48或72 h,采用光学显微镜和透射电镜分别观察芹黄素对Lovo细胞形态和超微结构的影响;采用四甲基偶氮唑盐比色法(MTT法)和平板克隆形成实验分别检测芹黄素对Lovo细胞增殖和克隆形成能力的影响;采用PI染色法、Annexin V FITC/PI双染法,流式细胞术分别检测芹黄素对Lovo细胞周期分布和凋亡的影响;采用Western blot法检测芹黄素对Bcl-2、pro-caspase-3、cleaved caspase-3表达的影响。结果芹黄素可浓度-时间依赖性的抑制人大肠癌Lovo细胞的增殖及克隆形成,作用48、72 h时的半数抑制浓度IC50分别为98.05μmol·L-1及33.91μmol·L-1;细胞周期分布发生改变,主要表现在G0/G1期细胞比例减少、G2/M期细胞比例增加,细胞周期阻滞于G2/M期;细胞凋亡率增加;Bcl-2、pro-caspase-3表达下调;cleaved caspase-3表达上调;差异具有统计学意义(P<0.05)。结论芹黄素可通过阻滞细胞周期于G2/M期抑制Lovo细胞增殖,通过下调Bcl-2、pro-caspase-3表达,上调cleaved caspase-3表达,诱导Lovo细胞凋亡,是一种有开发前景的大肠癌化疗药物。     

丁酸钠诱导结肠癌HT-29细胞凋亡的信号通路及对AQP3基因表达影响的研究

目的：探讨丁酸钠诱导结肠癌HT-29细胞凋亡过程的分子机理及其对水通道蛋白AQP3基因表达的影响。方法：MTT法检测不同浓度的丁酸钠对结肠癌HT-29细胞生长的影响;RT-PCR检测不同浓度的丁酸钠对细胞周期蛋白Cyclin D1、CDK4、p16和AQP3的基因表达水平,同时使用流式细胞仪检测细胞周期。结果：加入浓度超过2.5mmol/L的丁酸钠后,结肠癌HT-29细胞生长受到抑制,Cyclin D1、CDK4和AQP3的表达水平下降,p16的表达水平上调,细胞阻滞于G1/S期。结论：浓度超过2.5mmol/L的丁酸钠可以诱导结肠癌HT-29细胞凋亡,使其细胞周期阻滞于G1/S期,且这种诱导作用是剂量依赖型的,其分子通路可能是通过p16-Cyclin D1/CDK4这条信号途径,在此过程中,伴随着AQP3的基因表达水平降低。     

TNP-470对人结肠癌Lovo细胞增殖、细胞周期和凋亡的影响

目的　探讨TNP 4 70对体外培养的人结肠癌Lovo细胞增殖、细胞周期和凋亡的影响。方法　采用MTT法检测TNP 4 70对体外培养的Lovo细胞的生长抑制作用 ,流式细胞仪检测细胞周期分布及凋亡百分率。结果　TNP 4 70对Lovo细胞生长具有抑制作用 ,并存在量效和时间依赖性。流式细胞仪分析表明 :G0 /G1期细胞百分率上升 ,S期细胞百分率下降 ,增值指数 (PI)下降 ,凋亡率上升 ,电镜下可见典型的细胞凋亡形态改变。结论　TNP 4 70对Lovo细胞的增殖具有抑制作用 ,其机制与细胞周期阻滞和凋亡有关     

Increasing sensitivity to arsenic trioxide-induced apoptosis by altered telomere state

In this work, we investigated the synergic effects between low-dose arsenic trioxide and diethyloxadicarbocyanine (DODC), a telomerase inhibitor, on cell apoptosis. Results revealed that low-dose arsenic could block cell cycle arrest at the G2/M phase and induce apoptosis, whereas DODC could block cell cycle arrest at the G0/G1 phase but not induce apoptosis. However, cells pretreated with DODC showed greater sensitivity to arsenic than untreated cells. The percentage of apoptosis produced by combination treatment with the two agents increased and that was similar to the effect of high-dose arsenic treatment alone. Further studies showed that DODC alone could induce hairpin G-quadruplex formation and inhibit telomerase activity in a dose-dependent manner. Compared with HT1080 cells, 293 cells were more sensitive to cell growth inhibition and apoptosis and were less sensitivity to telomerase activity. These results indicate that DODC can synergistically enhance the apoptosis induced by arsenic, suggesting the increased cell senescence in response to arsenic is induced by an altered telomere state rather than by a loss of telomerase. Thus clinical application of combination treatment with arsenic and telomerase inhibitor may have potential in cancer therapy.     

榄香烯抑制Raf/MEK/ERK信号通路诱导人源胶质瘤U87细胞凋亡

目的探讨莪术提取物榄香烯体外诱导胶质瘤细胞凋亡的机制。方法采用流式细胞术、West-ern印迹等方法,分别检测不同浓度榄香烯对人源U87胶质瘤细胞的凋亡诱导及其对U87细胞Raf-1、ERK、癌基因Bcl-2蛋白质表达的影响。结果榄香烯对人源U87胶质瘤细胞具有明显的凋亡诱导作用,该增殖抑制效应呈时间依赖性。榄香烯可明显下调U87细胞的磷酸化Raf-1、ERK、Bcl-2表达。结论体外榄香烯对胶质瘤细胞具有明显的凋亡诱导作用(呈时间依赖性),抑制Raf/MEK/ERK信号通路,从而下调其下游信号癌基因Bcl-2的表达,最终启动凋亡程序可能是榄香烯诱导U87细胞凋亡的机制。     

Mechanism of cell proliferation--cell cycle, oncogenes, and senescence

Cell proliferation is regulated through a transition between the G0 phase and cell cycle. We isolated a mammalian temperature-sensitive mutant cell line defective in the function from the G0 phase to cell cycle. Senescent human somatic cells fail to enter into the cell cycle from the G0 phase with stimulation by any growth factor. Telomere shortening was found to be a cause of cellular senescence, and reexpression of telomerase immortalized human somatic cells. Immortalized human somatic cells showed normal phenotypes and were useful not only for basic research but also for clinical and applied fields. The importance of p53 and p21 activation/induction i now well accepted in the signal transduction process from telomere shortening to growth arrest, but the precise mechanism is largely unknown as yet. We found that the MAP kinase cascade and histone acetylase have an important role in the signaling process to express p21. Tumor tissues and cells were found to have strong telomerase activity, while most normal somatic human tissues showed very weak or no activity. Telomerase activity was shown to be a good marker for early tumor diagnosis because significant telomerase activity was detected in very early tumors or even in some precancerous tissues compared with adjacent normal tissues. Telomere/telomerase is a candidate target for cancer chemotherapeutics, and an agent that abrogated telomere functions was found to kill tumor cells effectively by inducing apoptosis whereas it showed no effect on the viability of normal cells.     

An investigation of the ability of elemene to pass through the blood‐brain barrier and its effect on brain carcinomas

Objectives Elemene is a chemical extracted from plants. It has demonstrated anti‐tumour capability. Although widely studied, there has been little reported regarding its tissue distribution. Our aim was to rectify this. Methods The tissue distribution of elemene was studied after intragastric or intravenous administration in rats. The effectiveness of elemene in treating brain tumours was studied using the G‐422 tumour cell model in mice. Key findings Elemene had a higher concentration in the lungs, spleen and livers than other tissues of normal rats after intragastric and intravenous administration, while the concentration in the gastrointestinal tract was greater after intragastric administration. Elemene molecules were also detected in the rats' brain tissue. Elemene had a therapeutic effect on mice inoculated with G‐422 cells both intracranially and subcutaneously. The best life‐extending rate and the best tumour‐inhibiting rate of elemene were 64.43% and 34.46%, respectively, when 80 mg/kg elemene was used for treatment. Conclusions The results from the tissue distribution study showed that elemene can pass through the blood‐brain barrier. The therapeutic experiments showed that elemene is effective in treating cerebral malignancy.