Resveratrol inhibits hypoxia-induced metastasis potential enhancement by restricting hypoxia-induced factor-1α expression in colon carcinoma cells

Resveratrol has been shown recently to exhibit antimetastatic effect on various human solid tumors. However, the possible molecular mechanism for its antimetastatic action needs to be elucidated. In this study, we investigated the effect of resveratrol on metastasis potential of colon carcinoma cells under normoxia and hypoxia in vitro. These results showed that, resveratrol can restrict the migration, adhesion, invasion and MMP-9 and MMP-2 secretion in Lovo cells cultured under normoxia and hypoxia. Hypoxia and iron chelator 2,2′-dipyridyl treatment can stimulate the invasion and migration enhancement of Lovo cells, while resveratrol exhibited substantial resistance on the metastasis potential stimulation by inhibiting the mRNA expression of VEGF and MMP-9 in colon carcinoma cells under normoxia and hypoxia, reducing HIF-1α protein expression under hypoxia. Also, iron chelator 2,2′-dipyridyl treatment showed approximately the same effect on metastasis potential as Lovo cells cultured under hypoxia. These data demonstrated that, the antimetastatic effect of resveratrol under hypoxia were associated with the restriction of HIF-1α protein expression and stabilization, which could be a promising drug target for resveratrol in the development of an effective chemopreventive and anticancer therapy in human tumors.     

Chrysin inhibits expression of hypoxia-inducible factor-1alpha through reducing hypoxia-inducible factor-1alpha stability and inhibiting its protein synthesis

Chrysin is a natural flavonoid and has been shown recently to have anticancer effects. However, the mechanisms that chrysin inhibits cancers are not well known. In this study, we investigated the effects of chrysin on expression of hypoxia-inducible factor-1alpha (HIF-1alpha) and vascular endothelial growth factor in human prostate cancer DU145 cells. Chrysin inhibited insulin-induced expression of HIF-1alpha by reducing its stability. Chrysin increases ubiquitination and degradation of HIF-1alpha by increasing its prolyl hydroxylation. In addition, chrysin interfered with interaction between HIF-1alpha and heat shock protein 90. Chrysin was also found to inhibit HIF-1alpha expression through AKT signaling. Inhibition of HIF-1alpha by chrysin resulted in abrogation of vascular endothelial growth factor expression. Finally, we showed that chrysin inhibited DU145 xenograft-induced angiogenesis in nude mice. Taken together, these results suggest that chrysin is a potent inhibitor of HIF-1alpha and provide a new sight into the mechanisms of chrysin against cancers.     

缺氧诱导因子-1α基因沉默对食管鳞癌细胞体外生长的影响

目的:探讨食管鳞癌细胞中缺氧诱导因子-1α(HIF-1α)基因与食管鳞癌细胞增殖活力和细胞周期的关系。方法:以RNA干扰方法构建出HIF-1α基因沉默食管鳞癌细胞株,通过Westernblot检测HIF-1α基因在细胞中的表达,通过流式细胞术分析了解HIF-1α基因沉默后细胞周期的变化,通过细胞增殖实验观察HIF-1α基因沉默细胞与对照细胞、模拟缺氧细胞增殖活性的差异。结果:细胞增殖实验发现沉默HIF-1α基因后的Eca-109细胞增殖活力较对照细胞明显低下,为对照细胞的62.6%(0.4768±0.1743vs0.7611±0.2165,P=0.012),流式细胞仪分析表明,HIF-1α基因沉默后的Eca-109细胞与对照细胞相比,G1/G0期细胞明显增加(P<0.05),G2/M期细胞变化不大,S期细胞比例明显减少。结论:核糖核酸干扰HIF-1α的表达后,能抑制鳞癌细胞的增殖活力,并可能阻滞肿瘤细胞周期,抑制HIF-1α的表达,有可能导致肿瘤生长的抑制。     

Green tea extract and (-)-epigallocatechin-3-gallate inhibit hypoxia- and serum-induced HIF-1alpha protein accumulation and VEGF expression in human cervical carcinoma and hepatoma cells

Green tea extract and its major component (-)-epigallocatechin-3-gallate (EGCG) exhibit antiangiogenic activities in various experimental tumor models. A growing body of evidence has established that hypoxia-inducible factor-1alpha (HIF-1alpha) and its downstream target, vascular endothelial growth factor (VEGF), play a critical role in tumor angiogenesis. In this study, we investigated the effect of green tea extract and EGCG on HIF-1alpha and VEGF expression in human cervical carcinoma (HeLa) and hepatoma (HepG2) cells. Our results showed that green tea extract and EGCG significantly inhibited hypoxia- and serum-induced HIF-1alpha protein accumulation in these cancer cells but had no effects on HIF-1alpha mRNA expression. Suppression of HIF-1alpha protein by green tea extract and EGCG also resulted in a drastic decrease in VEGF expression at both mRNA and protein levels. The mechanisms of green tea extract and EGCG inhibition of hypoxia-induced HIF-1alpha protein accumulation seem to involve the blocking of both phosphatidylinositol 3-kinase/Akt and extracellular signal-regulated kinase 1/2 signaling pathways and the enhancing of HIF-1alpha protein degradation through the proteasome system. In addition, green tea extract and EGCG inhibited serum-induced HIF-1alpha protein and VEGF expression by interfering with the phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin signaling pathways, which play a crucial role in the protein translational machinery cascade. Functionally, green tea extract and EGCG abolished both chemoattractant- and hypoxia-stimulated HeLa cell migration. Our data suggested that HIF-1alpha/VEGF function as therapeutic target for green tea extract and EGCG in the context of cancer chemoprevention and anticancer therapy.     

缺氧诱导因子1α对口腔鳞状上皮癌细胞株接受放射和化学药物治疗感受性的影响

背景:缺氧诱导因子1α是一种转录因子,缺氧环境下对哺乳动物细胞起重要的调控作用。然而缺氧诱导因子1α对口腔鳞状上皮癌细胞株的放疗和化疗感受性的作用有待研究。目的:观察缺氧诱导因子1α对口腔鳞状上皮癌细胞株接受放射和化学药物治疗感受性的影响。设计:观察对比实验。单位:首都医科大学附属北京朝阳医院。材料:口腔鳞状上皮癌细胞株-2,口腔鳞状上皮癌细胞株-4,口腔鳞状上皮癌细胞株-5,和口腔鳞状上皮癌细胞株-6来自人口腔鳞状上皮癌细胞(由日本高知大学医学部口腔外科建株)。方法:本实验于2004-09/2006-08于首都医科大学附属北京朝阳医院完成。将口腔鳞状上皮癌细胞株-2,口腔鳞状上皮癌细胞株-4,口腔鳞状上皮癌细胞株-5,和口腔鳞状上皮癌细胞株-6采用含小牛血清,左旋谷酰胺,青霉素,链霉素的改良DMEM培养液中培养。①从未处理和用30Gyγ射线,100μmol/L顺铂或100μmol/L5-氟脲嘧啶处理后的口腔鳞状上皮癌细胞株中提取细胞核蛋白。采用免疫印迹法检测缺氧诱导因子1α蛋白表达水平,同时采用定量PCR检测缺氧诱导因子1αmRNA的表达。②不同干预条件下细胞增殖抑制情况:将口腔鳞状上皮癌细胞株单细胞悬液以1×104/孔接种于96孔板中,每孔分别加入终浓度为100μmol/L的顺铂或5-氟尿嘧啶,或用30Gyγ射线处理细胞,培养48h后,采用用噻唑蓝比色法检测细胞增殖抑制情况。③不同干预条件下细胞凋亡分析:口腔鳞状上皮癌细胞株细胞用30Gyγ射线,100μmol/L顺铂或100μmol/L5-氟脲嘧啶处理24h后,用Propidi-umiodide和AnnexinV-FITC染色,用流式细胞仪测定凋亡细胞数(仅分析γ射线,顺铂处理组)。④质粒构建和转染:将人缺氧诱导因子1αcDNA克隆至pcDNA3.1/V5-HisTOPO表达载体。用脂质转染法将缺氧诱导因子1αcDNA暂时转染口腔鳞状上皮癌细胞株-2细胞。将缺氧诱导因子1αsiRNA(有义序列为5’CUGAUGACCAGCAACUUGAtt3’)暂时转染口腔鳞状上皮癌细胞株-5细胞,设立空白对照,同时给予细胞增殖抑制情况观察,以及细胞凋亡分析(仅分析顺铂处理组),方法同前。主要观察指标:①不同口腔鳞状上皮癌细胞株缺氧诱导因子1α的mRNA和蛋白表达情况。②不同干预条件下口腔鳞状上皮癌细胞株增殖抑制及细胞凋亡情况。③缺氧诱导因子1α过表达或缺氧诱导因子1α基因敲除的转染细胞的蛋白水平检测。④转染细胞和对照口腔鳞状上皮癌细胞株细胞增殖抑制情况和细胞凋亡分析结果。结果:①不同口腔鳞状上皮癌细胞株间缺氧诱导因子1αmRNA和蛋白表达结果:口腔鳞状上皮癌细胞株-2,口腔鳞状上皮癌细胞株-4,口腔鳞状上皮癌细胞株-5和口腔鳞状上皮癌细胞株-6细胞缺氧诱导因子1αmRNA的相对表达水平分别为1.0,2.2,4.3和4.0。缺氧诱导因子1α的细胞总蛋白和细胞核蛋白的表达在口腔鳞状上皮癌细胞株-2和口腔鳞状上皮癌细胞株-4细胞中较弱,而在口腔鳞状上皮癌细胞株-5和口腔鳞状上皮癌细胞株-6细胞中较强。②不同干预条件下口腔鳞状上皮癌细胞株细胞增殖抑制及被诱导凋亡情况:经γ射线,顺铂及5-氟脲嘧啶处理后,口腔鳞状上皮癌细胞株-2细胞数分别下降至(39.5±3.2)%,(39.2±1.2)%和(47.9±3.6)%,口腔鳞状上皮癌细胞株-4细胞数分别下降至(53.9±6.6)%,(54.3±1.4)%,(54.8+3.8)%。口腔鳞状上皮癌细胞株-5细胞数分别下降至(74.1±3.8)%,(76.5±9.1)%,(69.6±7.7)%,口腔鳞状上皮癌细胞株-6细胞数分别下降至(71.4±7.4)%,(84.4±8.8)%,(82.0±4.5)%。顺铂处理后,口腔鳞状上皮癌细胞株-2,口腔鳞状上皮癌细胞株-4,口腔鳞状上皮癌细胞株-5和口腔鳞状上皮癌细胞株-6细胞的凋亡细胞数分别为(50.9±1.3)%,(67.3±2.2)%,(12.2±0.8)%和(38.6±0.9)%。γ射线处理后,口腔鳞状上皮癌细胞株-2,口腔鳞状上皮癌细胞株-4,口腔鳞状上皮癌细胞株-5和口腔鳞状上皮癌细胞株-6细胞的凋亡细胞数分别为(21.2±1.1)%,(14.6±0.9)%,(9.7±1.0)%和(10.4±0.8)%。③不同干预条件下转染细胞增殖抑制及凋亡情况:经γ射线,顺铂及5-氟脲嘧啶处理后,转染了缺氧诱导因子1α表达载体的口腔鳞状上皮癌细胞株-2细胞数高于对照组(t=-4.693,-8.617,-6.721,P<0.01);转染了缺氧诱导因子1αsiRNA的口腔鳞状上皮癌细胞株-5细胞数低于对照组细胞(t=5.800,5.595,4.253,P<0.05～0.01)。用顺铂处理24h后,转染缺氧诱导因子-1α的口腔鳞状上皮癌细胞株-2细胞凋亡数为(34.0±1.9)%,低于空白对照[(49.6±3.4)%,t=6.937,P<0.01]。转染缺氧诱导因子1αsiRNA的口腔鳞状上皮癌细胞株-5细胞凋亡数为(27.7±2.3)%。高于空白对照[(11.4±2.1)%,t=-8.941,P<0.01]。结论:缺氧诱导因子1α表达与口腔鳞癌细胞对放、化疗感受性之间有负相关性。抑制癌细胞的缺氧诱导因子1α表达能增强癌细胞对放疗、化疗的感受性。     

缺氧诱导因子1α对口腔鳞状上皮癌细胞株接受放射和化学药物治疗感受性的影响

背景：缺氧诱导因子1α是一种转录因子，缺氧环境下对哺乳动物细胞起重要的调控作用。然而缺氧诱导因子1α对口腔鳞状上皮癌细胞株的放疗和化疗感受性的作用有待研究。目的：观察缺氧诱导因子1α对口腔鳞状上皮癌细胞株接受放射和化学药物治疗感受性的影响。设计：观察对比实验。单位：首都医科大学附属北京朝阳医院。材料：口腔鳞状上皮癌细胞株-2，口腔鳞状上皮癌细胞株-4，口腔鳞状上皮癌细胞株-5，和口腔鳞状上皮癌细胞株-6来自人口腔鳞状上皮癌细胞（由日本高知大学医学部口腔外科建株）。方法：本实验于2004—09／2006-08于首都医科大学附属北京朝阳医院完成。将口腔鳞状上皮癌细胞株-2，口腔鳞状上皮癌细胞株-4，口腔鳞状上皮癌细胞株-5，和口腔鳞状E皮癌细胞株-6采用含小牛血清，左旋谷酰胺，青霉素，链霉素的改良DMEM培养液中培养。①从未处理和用30Gyγ射线，100μmol／L顺铂或100μmol／L5-氟脲嘧啶处理后的口腔鳞状上皮癌细胞株中提取细胞核蛋白。采用免疫印迹法检测缺氧诱导因子1α蛋白表达水平，同时采用定量PCR检测缺氧诱导因子1αmRNA的表达。②不同干预条件下细胞增殖抑制情况：将口腔鳞状上皮癌细胞株单细胞悬液以1&;#215;10^4／孔接种于96孔板中，每孔分别加入终浓度为100μmol／L的顺铂或5-氟尿嘧啶，或用30Gyγ射线处理细胞，培养48h后，采用用噻唑蓝比色法检测细胞增殖抑制情况。③不同干预条件下细胞凋亡分析：口腔鳞状上皮癌细胞株细胞用30Gyγ射线，100μmol／L顺铂或100μmol／L5-氟脲嘧啶处理24h后，用Propidium iodide和Annexin V—FITC染色，用流式细胞仪测定凋亡细胞数（仅分析γ射线，顺铂处理组）。④质粒构建和转染：将人缺氧诱导因子1α cDNA克隆至pcDNA3．1／V5-His TOPO表达载体。用脂质转染法将缺氧诱导因子1α cDNA暂时转染口腔鳞状上皮癌细胞株-2细胞。将缺氧诱导因子1α siRNA（有义序列为5’CUGAUGACCAGCAACUUGAtt3’）暂时转染口腔鳞状上皮癌细胞株-5细胞，设立空白对照，同时给于细胞增殖抑制情况观察，以及细胞凋亡分析（仅分析顺铂处理组），方法同前。主要观察指标：①不同口腔鳞状上皮癌细胞株缺氧诱导因子1α的mRNA和蛋白表达情况。②不同干预条件下口腔鳞状上皮癌细胞株增殖抑制及细胞凋亡情况。⑧缺氧诱导因子1α过表达或缺氧诱导因子1α基因敲除的转染细胞的蛋白水平检测。㈤转染细胞和对照口腔鳞状上皮癌细胞株细胞增殖抑制情况和细胞凋亡分析结果。结果：①不同口腔鳞状上皮癌细胞株间缺氧诱导因子1αmRNA和蛋白表达结果：口腔鳞状上皮癌细胞株-2，口腔鳞状上皮癌细胞株-4，口腔鳞状上皮癌细胞株-5和口腔鳞状上皮癌细胞株-6细胞缺氧诱导因子1αmRNA的相对表达水平分别为1、0，2．2，4.3和4．0。缺氧诱导因子1α的细胞总蛋白和细胞核蛋白的表达在口腔鳞状上皮癌细胞株-2和口腔鳞状上皮癌细胞株-4细胞中较弱，而在口腔鳞状上皮癌细胞株-5和口腔鳞状上皮癌细胞株-6细胞中较强。②不同干预条件下口腔鳞状上皮癌细胞株细胞增殖抑制及被诱导凋亡情况：经γ射线，顺铂及5-氟脲嘧啶处理后，口腔鳞状上皮癌细胞株-2细胞数分别下降至（39．5&;#177;3．2）％，（39．2&;#177;1．2）％和（47．9&;#177;3．6）％，口腔鳞状上皮癌细胞株-4细胞数分别下降至（53．9&;#177;6．6）％，（54.3&;#177;1.4）％，（54．8＋3．8）％。口腔鳞状上皮癌细胞株-5细胞数分别下降至（74．1&;#177;3．8）％，（76．5&;#177;9．1）％，（69．6&;#177;7．7）％，口腔鳞状上皮癌细胞株-6细胞数分别下降至（71.4&;#177;7．4）％，（84．4&;#177;8．8）％，（82．0&;#177;4．5）％。顺铂处理后，口腔鳞状上皮癌细胞株-2，口腔鳞状上皮癌细胞株-4，口腔鳞状上皮癌细胞株-5和口腔鳞状上皮癌细胞株-6细胞的凋亡细胞数分别为（50．9&;#177;1.3）％，（67.3&;#177;2．2）％，（12．2&;#177;0．8）％和（38．6&;#177;0．9）％。γ射线处理后，口腔鳞状上皮癌细胞株-2，口腔鳞状上皮癌细胞株-4，口腔鳞状上皮癌细胞株-5和口腔鳞状上皮癌细胞株-6细胞的凋亡细胞数分别为（21．2&;#177;1．1）％，（14．6&;#177;O．9）％，（9．7&;#177;1．0）％和（10．4&;#177;0．8）％。⑧不同干预条件下转染细胞增殖抑制及凋亡情况：经γ射线，顺铂及5-氟脲嘧啶处理后，转染了缺氧诱导因子1α表达载体的口腔鳞状上皮癌细胞株-2细胞数高于对照组（t=-4．693，-8．617，-6．721，P〈0．01）；转染了缺氧诱导因子1α siRNA的口腔鳞状上皮癌细胞株-5细胞数低于对照组细胞（t=5．800，5．595，4．253，P〈0．05～0．011。用顺铂处理24h后，转染缺氧诱导因子-1α的口腔鳞状上皮癌细胞株-2细胞凋亡数为（34．0&;#177;1．9）％，低于空白对照[（49．6&;#177;3．4）％，t=6．937，P〈0．01]。转染缺氧诱导因子1α siRNA的口腔鳞状上皮癌细胞株-5细胞凋亡数为（27．7&;#177;2.3）％。高于空白对照[（11．4&;#177;2．1）％，t=-8．941，P〈0．01]。结论：缺氧诱导因子1α表达与口腔鳞癌细胞对放、化疗感受性之间有负相关性。抑制癌细胞的缺氧诱导因子1α表达能增强癌细胞对放疗、化疗的感受性．     

纳米介导的缺氧诱导因子1α小干扰RNA抑制人食管鳞癌TE-1细胞生长

背景:纳米微粒作为一种比较理想的非病毒基因递送载体,具有无免疫原性和致瘤性等优越性.利用纳米技术和基因干扰技术阻断缺氧诱导因子1α(hypoxia-inducible factor 1,HIF-1α)在食管鳞癌组织的表达,降低癌细胞对化疗药物的耐药性,理论上成为能够抑制食管癌细胞生长的有效方法.目的:探讨HIF-1α小干扰RNA纳米微粒对人食管鳞癌TE-1细胞生长的抑制作用.设计、时间及地点:以体外培养的食管鳞癌TE-1细胞为对象,基因水平完全随机对照实验,于2007-01/2008-12在中山大学附属第三医院中心实验室完成.材料:由上海生物工程公司合成HIF-1α小干扰RNA,采用超声乳化法制备纳米微粒.人食管鳞癌TE-1细胞株购自中科院上海细胞库.方法:体外培养的人食管鳞癌TE-1细胞分为4组:分别为生理盐水组,不含基因的纳米微粒组,HIF-1α小干扰RNA组,HIF-1α小干扰RNA纳米微粒组.主要观察指标:RT-PCR检测HIF-1αmRNA的表达,Western-blot法检测HIF-1α蛋白的表达;流式细胞仪检测细胞凋亡情况;MTT法检测细胞增殖情况.结果:处理72 h后HIF-1α小干扰RNA纳米微粒组细胞的HIF-1αmRNA表达和HIF-1α蛋白表达低于其他3组(P＜0.01),细胞凋亡率高于其他3组(P＜0.01).HIF-1α小干扰RNA纳米微粒组细胞增殖受明显抑制,生长缓慢,与其他3组比较,差异有显著性意义(P＜0.01).结论:HIF-1α小干扰RNA纳米微粒能够有效减少食管鳞癌TE-1细胞的HIF-1αmRNA和蛋白的表达,提高肿瘤细胞的凋亡,显著抑制TE-1细胞的生长.     

缺氧诱导因子1α在大鼠急性缺血心肌组织中的变化

目的:了解缺氧诱导因子1αmRNA和蛋白质在大鼠急性缺血心肌组织中表达的变化规律。方法:实验在南通大学生物技术系,江苏省神经生物学重点实验室完成。①实验分组:雄性SD大鼠78只,其中42只大鼠随机分为7组,每组6只,分别设为空白对照组(0h)和缺血0.5h,1h,1.5h,2h,3h,4h组,检测缺氧诱导因子1αmRNA表达变化。另外36只大鼠随机分为6组,每组6只,分别设为空白对照组(0h)和缺血1h,2h,4h,5h,6h组,检测缺氧诱导因子1α蛋白表达变化。②实验方法:通过结扎大鼠左冠状动脉前降支,构建左室心肌缺血模型。术中心电图等证明结扎成功后,分别在上述不同时间点取缺血心肌组织,分别运用反转录聚合酶链式反应法和免疫组织化学方法检测缺血心肌组织中缺氧诱导因子1αmRNA和蛋白质的表达变化。结果:缺氧诱导因子1αmRNA和蛋白质在正常大鼠心肌中微量表达,心肌缺血后表达明显增高,并随缺血时间变化而变化。0.5h缺氧诱导因子1αmRNA表达显著增加(P<0.05),1.0～2.0h达到高峰(P<0.01),以后逐渐下降并趋向基线。心肌缺血后1h缺氧诱导因子1α蛋白质表达明显上升(P<0.05),4h达到高峰(P<0.01),随缺血时间延长表达回降。结论:缺氧诱导因子1α在缺血心肌组织中高表达。缺氧诱导因子1α在大鼠缺血心肌组织中表达的上调,可能参加了心肌缺血的代偿机制,有助于改善心肌供血。     

Acute intensive insulin therapy exacerbates diabetic blood-retinal barrier breakdown via hypoxia-inducible factor-1alpha and VEGF

Acute intensive insulin therapy is an independent risk factor for diabetic retinopathy. Here we demonstrate that acute intensive insulin therapy markedly increases VEGF mRNA and protein levels in the retinae of diabetic rats. Retinal nuclear extracts from insulin-treated rats contain higher hypoxia-inducible factor-1alpha (HIF-1alpha) levels and demonstrate increased HIF-1alpha-dependent binding to hypoxia-responsive elements in the VEGF promoter. Blood-retinal barrier breakdown is markedly increased with acute intensive insulin therapy but can be reversed by treating animals with a fusion protein containing a soluble form of the VEGF receptor Flt; a control fusion protein has no such protective effect. The insulin-induced retinal HIF-1alpha and VEGF increases and the related blood-retinal barrier breakdown are suppressed by inhibitors of p38 mitogen-activated protein kinase (MAPK) and phosphatidylinositol (PI) 3-kinase, but not inhibitors of p42/p44 MAPK or protein kinase C. Taken together, these findings indicate that acute intensive insulin therapy produces a transient worsening of diabetic blood-retinal barrier breakdown via an HIF-1alpha-mediated increase in retinal VEGF expression. Insulin-induced VEGF expression requires p38 MAPK and PI 3-kinase, whereas hyperglycemia-induced VEGF expression is HIF-1alpha-independent and requires PKC and p42/p44 MAPK. To our knowledge, these data are the first to identify a specific mechanism for the transient worsening of diabetic retinopathy, specifically blood-retinal barrier breakdown, that follows the institution of intensive insulin therapy.     

siRNA抑制人肝癌细胞MDM2表达及细胞增殖的研究

目的探讨siRNA对人肝癌HepG2细胞MDM2基因表达的抑制作用及对增殖的影响。方法体外合成针对MDM2基因的siRNA质粒,转染HepG2细胞株;应用RT-PCR和western blot方法检测siRNA对MDM2和P53基因和蛋白表达的影响,并用MTT法检测siRNA对细胞增殖抑制作用,流式细胞仪检测细胞周期。结果和空白组比转染siMDM2-1,2的HepG2细胞的MDM2基因和蛋白表达减低,而P53基因和蛋白表达增加。阴性对照质粒组的基因表达未见明显改变。转染siRNA MDM2后细胞生长受到抑制,转染siMDM2-1,2和阴性对照质粒后的抑制率分别是46.3%、56.1%和3%。和对照组比较,转染siMDM2-1,2的hepG2细胞的细胞周期发生明显改变,而转染对照质粒的hepG细胞周期未发生明显变化。结论 siRNA MDM2可以有效抑制HepG2细胞株中MDM2的表达,促进P53的表达,同时可以使细胞周期发生变化,这可能是其抑制肿瘤细胞增殖的主要机制之一。     

构建双突变型低氧诱导因子1α腺病毒载体的实验

目的:前期实验已成功构建无突变及564位是单突变腺病毒载体。在此基础上构建人双突变型低氧诱导因子1α腺病毒表达载体,为进一步研究低氧诱导因子1α基因及其突变体的临床应用奠定基础。方法:实验于2005-12/2006-12在南方医院心内科重点实验室完成。①实验材料:限制性内切酶PacI(NEB),PI-SceI、I-CeuI(Clontech);IPTG、X-Gal(Takara),转染试剂Lipofectamine2000(Invitrogen),凝胶回收试剂盒(Omega);DMEM(Omega);小牛血清(PAA);北京天为时代公司病毒基因组提取试剂盒;HIF-1α单克隆抗体(Chemicon International公司);羊抗鼠辣根过氧化物酶标记二抗(北京鼎国生物公司)。质粒、菌珠、细胞系等:Adeno-XTM-Adenoviral Expression Systems(BD.CLONTECH):包括有pShuttle2、pShuttle2-lacZ、Adeno-XTMViralDNA等;重组穿梭质粒pShuttle2-HIF-1α-Ala564-Ala803及pShuttle2-lacZ(本室已构建成功);大肠杆菌DH5α(本室保存);HEK293A细胞(中科院上海细胞所)。②实验方法:采用分子克隆技术,以PI-SceI和I-CeuI双酶切重组穿梭质粒pShuttle2-HIF-1α-Ala564-Ala803,然后切下含有低氧诱导因子1αcDNA表达的盒片段,通过体外连接法与线性化的腺病毒骨架质粒Adeno-XViralDNA连接,重组成pAdeno-HIF-1α腺病毒质粒,经酶切及测序鉴定正确后,在HEK293A细胞中包装成为重组腺病毒Adeno-HIF-1α-Ala564-Ala803。③实验评估:进行PCR鉴定及滴度测定。用重组腺病毒转染293A,采用Westernblot鉴定低氧诱导因子1α蛋白表达。结果:提取重组腺病毒质粒pAdeno-HIF-1α-Ala564-Ala803以引物A、B和引物1、2、3、4进行PCR鉴定,分别扩增出287,460,214bp的3种引物片段,与预期一致,经酶切鉴定及基因测序证实重组腺病毒质粒构建成功。pAdeno-lacZ转染293A细胞后X-Gal原位染色,显示约有近20%左右细胞染成蓝色,病毒滴度为6.8×107pfu/mL。Adeno-HIF-1α-Ala564-Ala803转染293A后稳定表达低氧诱导因子1α蛋白。结论:成功构建了重组腺病毒突变型的Adeno-HIF-1α-Ala564-Ala803。     

低氧诱导因子1α慢病毒载体转染骨髓间充质干细胞的成骨基因表达

背景：成骨作用和血管发生在骨的形成和修复过程中紧密结合,而低氧诱导因子1α被认为是促血管新生相关基因调控中最重要的核心转录因子,其可促进缺氧部位血管的形成,进而促进骨的形成。 目的：构建野生型和点突变型两个低氧诱导因子1α慢病毒真核表达载体 Lenti-HIF1α-IRES-EGFP,并比较其对兔骨髓间充质干细胞成骨基因表达的影响。 方法：首先根据野生型人源低氧诱导因子1α基因序列信息和确定酶切位点的点突变型序列信息构建低氧诱导因子1α基因野生型和点突变型两个慢病毒真核表达载体;然后采用制备的病毒液转染兔骨髓间充质干细胞。 结果与结论：免疫荧光显微镜观察显示,转染7 d后野生型组和点突变型组细胞均未见明显荧光,转染14 d后两组细胞均呈现明显的绿色荧光;qPCR定量分析结果表明,转染7 d后即有低氧诱导因子1α和骨形态发生蛋白2基因的显著表达,转染14 d后,两基因仍然显示较高的表达水平。说明实验成功构建野生型和点突变型低氧诱导因子1α基因慢病毒真核表达载体,转染后可以促进兔骨髓间充质干细胞成骨基因的表达。     

Apoptotic effect of MG-132 on human tongue squamous cell carcinoma

The aim of this study was to investigate the apoptotic effect of a proteasome inhibitor MG-132 on Tca-8113, a cell line of human tongue squamous cell carcinoma. Tca-8113 cells were treated with 10, 20, and 30 μM of MG-132, or 5 μM thapsigargin. Apoptosis rate was determined with annexin V/propidium iodide double staining. Expression of E3ubiquitin-protein ligase was determined by ELISA, and Grp78 and caspase-12 mRNA, and Grp78 and caspase-12 protein was assessed by RT-PCR and Western blot, respectively. Apoptosis was observed 18 h after MG-132 treatment. The apoptotic rate in the 10, 20, and 30 μM MG-132 group was 13.5, 19.6 and 34.7%, respectively, which was higher than in the thapsigargin (8.5%, P < 0.01) or control group (0.5%, P < 0.01). The expression of E3 ubiquitin-protein ligase in the 10, 20, and 30 μM MG-132 group was 28.75 ± 2.28, 18.16 ± 0.65, 8.85 ± 0.72, respectively, which was lower than in the thapsigargin (38.96 ± 0.33, P < 0.05 or 0.01) or control (40.88 ± 4.52, P < 0.05 or 0.01) group. The levels of Grp78 and capase-12 mRNA, Grp78 and caspase-12 protein in the MG-132 groups were higher than in the control group (P < 0.01). In conclusion, MG-132 induces apoptosis in Tca-8113 cells in a concentration-dependent manner. The MG-132-induced apoptosis may involve downregulation of E3 ubiquitin ligase, and upregulation of Grp78 and caspase-12.     

Resveratrol inhibits tumor necrosis factor-α-mediated matrix metalloproteinase-9 expression and invasion of human hepatocellular carcinoma cells

Resveratrol is an active polyphenol found in red wine that has anti-cancer effects, but the molecular mechanisms of resveratrol on tumor invasion inhibition have not been well documented. The aim of this study was to elucidate the effects of resveratrol on invasion ability of human hepatocellular carcinoma cells and TNF-alpha-mediated MMP-9 expression. The expression activity of MMP-9 was measured by zymography, RT-PCR and western blot analysis. The expression of NF-kappa B was measured by EMSA and western blot analysis. TNF-alpha induced the MMP-9 expression in HepG2 cells. Resveratrol significantly inhibited TNF-alpha-mediated MMP-9 expression in HepG2 cells. NF-kappa B inhibitor induced a marked reduction in MMP-9 expression, and it suggested that NF-kappa B could play an important role in TNF-alpha-mediated MMP-9 expression. Furthermore, resveratrol significantly suppressed TNF-alpha-mediated NF-kappa B expression and invasion of HepG2 cells. Our results showed that resveratrol inhibited TNF-alpha-mediated MMP-9 expression and invasion of human hepatocellular carcinoma cells. The inhibitory effects are partly associated with the downregulation of the NF-kappa B signaling pathway.     

Regulation of hypoxia-inducible factor-1alpha by cyclical mechanical stretch in rat vascular smooth muscle cells

Vascular smooth muscle cells (VSMCs) are exposed to hormonal and mechanical stress in vivo. Hormonal factors have been shown to affect hypoxia-inducible factor-1alpha (HIF-1alpha). How mechanical stress affects the regulation of HIF-1alpha in VSMCs has not been reported previously, and therefore we sought to investigate the regulation of HIF-1alpha by cyclical mechanical stretch in cultured rat VSMCs. Rat VSMCs grown on a flexible membrane base were stretched by vacuum to 20% of the maximum elongation at 60 cycles/min. The levels of HIF-1alpha protein began to increase as early as 2 h after stretch was applied and reached a maximum of 2.8-fold over the control by 4 h. Real-time PCR showed that the levels of HIF-1alpha mRNA increased 2.1-fold after cyclical stretch for 4 h. Cyclical mechanical stretch also increased the immunohistochemical labelling of HIF-1alpha in VSMCs after cyclical stretch for 4 h. The phosphorylation of p42/p44 mitogen-activated protein kinase (MAP kinase) increased after stretch and this was inhibited by the MAP kinase kinase inhibitors PD98059 and U0126. PD98059 and U0126 also blocked HIF-1alpha gene expression induced by cyclical stretch. In conclusion, cyclical mechanical stretch activates the gene expression of HIF-1alpha in cultured VSMCs and this mechanical effect is possibly mediated by the p42/p44 MAP kinase kinase pathway.     

骨髓间充质干细胞中突变型人低氧诱导因子1α真核表达载体的表达

背景:转基因小鼠体内实验证实,重组的低氧诱导因子1α可以促进皮肤形态功能正常的血管新生.目的:构建能够在常氧条件下同时表达突变型低氧诱导因子1α目的蛋白和绿色荧光蛋白报告分子的新型腺病毒真核表达载体,并转染SD大鼠骨髓间充质干细胞,检测该基因在细胞中的表达情况.方法:利用Lipofectamine 2000介导将构建成功的重组腺病毒真核表达载体pAd-HIF1αmu- IRES-hrGFP-1转染HEK293A细胞,包装病毒,以最佳感染指数=50将重组腺病毒转染大鼠骨髓间充质干细胞,并设3个对照组,即阳性对照组:转染Ad-CMV-HIF1α-IRES-hrGFP-1;阴性对照组:转染Ad-CMV-IRES-hrGFP-1组;空白组:未转染病毒.结果与结论:①腺病毒载体成功转染HEK293A细胞,包装成功,细胞内有大量绿色荧光表达.②转染突变型低氧诱导因子1α腺病毒表达载体的细胞在常氧条件下蛋白表达量明显高于转其他3组,3个对照组间差异无显著性意义(P > 0.05).提示突变型腺病毒真核表达载体Ad-HIF1α-IRES-hrGFP-1在HEK293A内成功包装;突变后低氧诱导因子1α基因能够在常氧条件下大量且高效表达.