5-Aza-CdR体外诱导胃癌细胞系p16基因去甲基化及表达增强

目的: 观察去甲基化制剂--5-Aza-CdR对体外培养的胃癌细胞SGC7901 p16基因启动子区甲基化状态及表达的影响, 探讨胃癌细胞p16基因失活的机制及去甲基化制剂对p16基因表达的调控.方法:应用不同浓度的5-Aza-CdR(1×10-7, 5×10-7, 1×10-6, 5×10-6 mol/L)处理体外培养的胃癌细胞SGC7901后, MSP法检测用药前后细胞中p16基因的甲基化状态, RT-PCR及 Western-blot法检测用药前后细胞中p16基因mRNA及蛋白表达的变化.结果: p16基因在胃癌细胞系SGC7901中启动子区呈异常甲基化状态, 在mRNA及蛋白水平低表达. 经过1×10-7, 5×10-7, 1×10-6, 5×10-6 mol/L 5-Aza-CdR处理后, p16基因启动子区呈去甲基化状态, 各组mRNA及蛋白表达相应的比值分别与处理前的比例为2.21±0.36, 2.01±0.31;2.82±0.39, 2.22±0.33;2.98±0.42, 3.15±0.43及3.35±0.55, 3.75±0.61.结论:5-Aza-CdR能逆转胃癌细胞p16基因甲基化状态, 调控p16基因表达.     

5-Aza-CdR对胃癌细胞系生长及Apaf-1基因异常甲基化的影响

目的:观察5-氮杂-2′-脱氧胞苷(5-aza-2′-deoxycitydine,5-Aza-CdR)对体外培养的胃癌SGC7901细胞和BGC823细胞增生、细胞周期和凋亡的影响及其对此两株细胞中Apaf-1基因的甲基化状态的影响.方法:不同浓度5-Aza-CdR处理体外培养的SGC7901细胞和BGC823细胞后,用MTT法检测处理24,48和72 h的细胞增殖活性;PI染色和流式细胞仪检测药物处理后72 h细胞周期分布和细胞凋亡率;MSP法检测用药前后细胞中Apaf-1基因的甲基化状态;RT-PCR法及Western blot法检测用药前后细胞中Apaf-1的mRNA及蛋白表达的变化.结果:1×10-7,5×10-7,1×10-6和5×10-6 mol/L5-Aza-CdR处理SGC7901和BGC823细胞24,48,72 h后,细胞增生受到抑制,有时间和剂量的依赖性.流式细胞仪分析表明,各药物浓度处理72 h后凋亡率增加明显:SGC7901细胞5×10-7,1×10-6和5×10-6 mol/L组分别为2.53%±1.19%,5.93%±0.86%,10.14%±1.51%,与对照组(0.12%±0.03%)相比差异显著(P＜0.05);BGC823细胞5×10-7,1×10-6和5×10-6 mol/L组分别为1.57%±0.26%,4.64%±1.05%,8.21%±1.46%,与对照组(0.57%±0.03%)相比差异显著(P＜0.05).在5-Aza-CdR处理前未检测到SGC7901细胞系及BGC823细胞系的Apaf-1基因的mRNA及蛋白表达,经过5-Aza-CdR处理后,Apaf-1基因在SGC7901细胞系及BGC823细胞系中甲基化状态得到了逆转,Apaf-1基因的mRNA及蛋白重新表达.结论:5-Aza-CdR对SGC7901细胞和BGC823细胞具有增生抑制作用;Apaf-1基因的表达情况与其甲基化状态的改变有关.     

曲古菌素A对人胃癌细胞增殖和细胞周期的作用

目的 观察曲古菌素A(TSA)对人胃癌细胞株SGC-7901细胞增殖及细胞周期的影响,探讨其可能的机制.方法 TSA干预人胃癌SGC-7901细胞24 h后.采用四甲基偶氮唑盐法检测其对细胞增殖的影响,流式细胞技术检测细胞周期,实时PCR检测细胞周期素D1和p21 mRNA的表达情况.结果 经TSA干预24 h后,人胃癌SGC-7901细胞增殖受抑制,TSA 0.1、0.5和2.0μmol/L组抑制率分别为3.52%±6.11%、13.29%±4.13%和14.24%±2.80%;同时TSA 0.5μmol/L组(71.26%±0.51%)和TSA 2.0μmol/L组(71.03%±0.12%)的G0/Gl期细胞比例明显高于对照组(51.12%±1.17%);TSA 0.5μmol/L组(13.55%±0.44%)和TSA 2.0 μmol/L组(10.63%±0.63%)的S期细胞比例明显低于对照组(34.60%±0.60%).出现G0/G1细胞周期阻滞.TSA干预后细胞周期相关基因细胞周期素D1 mRNA表达下调和p21 mRNA表达上调.结论 TSA通过调控细胞周期相关基因细胞周期素D1和p21的表达,抑制人胃癌SGC-7901细胞的增殖,引起G0/G1期细胞周期阻滞,最终影响肿瘤细胞的生长.     

5-氮杂-2′-脱氧胞苷对胃癌AGS细胞CHFR基因去甲基化作用及意义

目的观察5-氮杂-2′-脱氧胞苷（5-Aza-CdR）对胃癌AGS细胞CHFR基因去甲基化的作用,并探讨其临床意义。方法分别采用BSP和RT-PCR技术检测5-Aza-CdR处理前后胃癌AGS细胞CHFR基因启动子甲基化状态及其mRNA。结果 AGS细胞CHFR基因启动子在5-Aza-CdR处理前呈现高甲基化状态（甲基化率≥60%）,其mRNA表达完全缺失;5-Aza-CdR处理后则表现为低或无甲基化状态（甲基化率≤20%）,其mRNA表达恢复正常。结论 CHFR基因启动子在AGS细胞中呈高甲基化状态,5-Aza-CdR能显著逆转其CHFR基因异常甲基化,诱导CHFR基因表达,为胃癌的治疗提供新思路。     

5-氮杂-2′-脱氧胞苷对结肠腺癌细胞株Caco-2细胞生物学行为的影响

[目的]研究去甲基化5-氮杂-2′-脱氧胞苷(5-Aza-CdR)对人结肠腺癌细胞株Caco-2细胞生长周期及凋亡的影响,探讨其临床治疗的可能性。[方法]分别使用0.4、1.6、6.4、25.6、102.4μmol/L浓度的5-Aza-CdR处理Caco-2细胞;通过MTT检测5-Aza-CdR对Caco-2细胞存活率的影响;应用流式细胞检测5-Aza-CdR对Caco-2细胞生长周期及凋亡的影响;RT-PCR检测处理前后抑癌基因RASSF1A mRNA表达的改变。[结果]1.6μmol/L浓度的5-Aza-CdR可以明显的抑制Caco-2细胞的增殖,细胞周期中处于G0/G1期的细胞明显的增多,阻滞于G1期,凋亡率增高;5-Aza-CdR的作用与其浓度、时间在一定范围内呈正相关。5-Aza-CdR处理后,无RASSF1A表达的Caco-2细胞可检测出基因RASSF1A的重新表达。[结论]5-Aza-CdR可消除某些抑癌基因启动子甲基化状态,使其重新表达而抑制Caco-2细胞的生长,并促进其凋亡。     

结肠癌Lovo细胞RUNX3基因的表达与其增殖及凋亡的关系

目的:探讨5-氮-2'-脱氧胞苷(5-Aza-CdR)对人结肠癌Lovo细胞增殖凋亡及抑癌基因RUNX3表达的影响.方法:用特异性甲基转移酶抑制剂5-Aza-CdR0.4,4,40 μmol/L处理人结肠癌细胞株Lovo 3d,继续常规培养5d后,采用四唑盐法(MTT)比色法观察细胞经药物处理前后的生长活性.以半定量RT-PCR检测细胞处理前后抑癌基因RUNX3 mRNA的表达,以甲基化特异性PCR(methylation-specific PCR,MSP)检测细胞处理前后RUNX3的甲基化状态,应用流式细胞仪进行细胞凋亡率的检测.结果:与对照组相比,0.4,4,40 μmol/L的5.Aza-CdR处理细胞后.细胞RUNX3mRNA的相对表达量(0.46±0.06,0.71±0.06,0.84±0.07 vs 0,P＜0.01)和细胞凋亡率均增高(10.95%±2.09%,17.61%±1.51%,26.60%±1.89%vs 2.92%±0.93%,P＜0.01).呈剂量依赖性(F=168.4,F=145.7),结肠癌Lovo细胞生长速率下降,RUNX3 mRNA重新表达,其基因启动子区域部分甲基化.结论:5-Aza-CdR可逆转RUNX3启动子高甲基化状态,抑制细胞生长,诱导部分细胞凋亡.     

5-氮杂-2＇-脱氧胞苷对胃癌AGS细胞增殖、凋亡的影响及机制探讨

目的观察5-氮杂-2＇-脱氧胞苷（5-Aza-CdR）对胃癌AGS细胞增殖、凋亡的影响,并探讨其机制。方法分别用低、中、高浓度5-Aza-CdR处理AGS,对照组不处理。CCK-8检测AGS细胞增殖状态,流式细胞仪检测AGS细胞周期及凋亡率,MSP检测AGS中DAPK基因启动子甲基化状态,RT-PCR和Western blot法分别检测AGS中的DAPKmRNA及其蛋白。结果低、中、高浓度组AGS细胞增殖速度显著低于对照组（P均〈0.05）,并呈浓度、时间依赖性（P均〈0.05）。5-Aza-CdR使AGS细胞停滞在G0/G1期（P均〈0.05）,细胞凋亡率增加（P均〈0.05）。对照组DAPK基因启动子表现甲基化状态,低、中、高浓度组DAPK基因启动子被逆转成未甲基化状态。低、中、高浓度组AGS细胞DAPK mRNA及蛋白表达量均显著高于对照组（P均〈0.05）,并呈浓度依赖性。结论 5-Aza-CdR可抑制AGS细胞增殖、促进其凋亡,可能与逆转DAPK基因启动子甲基化状态并使其重新表达有关。     

microRNA-433在胃癌组织中的表达下降及对胃癌细胞系生长的影响

目的:探讨胃癌组织中microRNA-433表达差异以及其可能下调的机制,及在低表达microRNA-433胃癌细胞系中提升其表达的量对细胞生长的影响.方法:取胃癌组织及其正常癌旁组织43例,实时定量检测两者表达差异,并结合病例分析.使用1、5、10mol/L5-Aza-CdR干预胃癌SGC-7901细胞,检测每组microRNA-433的表达变化.转染microRNA-433mimics进入SGC-7901细胞,用流式细胞术检测细胞增殖凋亡情况.结果:胃癌组织相对其正常癌旁组织,microRNA-433表达量明显减低,差异有明显统计学意义(P<0.05),microRNA-433表达与性别、分化、年龄无明显关系(P>0.05),同肿瘤分期有统计学意义(P<0.05).胃癌细胞系SGC-7901中microRNA-433的表达相对于正常胃黏膜上皮细胞GES-1明显减低.SGC-7901细胞通过甲基化酶抑制剂5-Aza-CdR以浓度1、5、10mol/L处理5d之后,分别检测microRNA-433的表达,相对未处理组,其表达均有上升并且呈现出剂量依赖性.将microRNA-433mimics转染至SGC-7901中提高其表达,通过流式细胞术检测发现,相比未处理组,提高表达后肿瘤细胞凋亡率上升,具有统计学意义(P<0.05).结论:microRNA-433在胃癌组织中表达减低,并且同肿瘤分期有关.使用5-Aza-CdR作用SGC-7901肿瘤细胞系后,microRNA-433的表达明显上升.其表达下调的机制可能是由于前端启动子区域高甲基化造成,转染提升肿瘤细胞中microRNA-433的表达,可以促进肿瘤细胞的凋亡.microRNA-433具有潜在的抑癌作用.     

S-腺苷蛋氨酸对人胃癌细胞系增殖及c-myc、uPA基因甲基化的影响

目的 观察S-腺苷蛋氨酸(SAM)对体外培养的人胃癌细胞的细胞周期、凋亡以及侵袭力的影响,及对细胞中c-myc基因和尿激酶型纤溶酶原激活剂(uPA)基因甲基化状态及表达的影响.方法 用不同浓度(0、2、4 mmol/L)SAM处理体外培养的MKN-28、SGC-7901和MKN-45细胞72h,用流式细胞仪检测各组细胞周期分布和细胞凋亡率;Transwell法检测各组细胞侵袭力的改变;RT-PCR法检测各组细胞c-myc基因和uPA基因mRNA表达的变化;甲基化特异性PCR法检测各组细胞中c-myc基因和uPA基因的甲基化状态.结果随SAM浓度增加,3种细胞凋亡率均明显增加(P值均<0.01),侵袭力均受到明显抑制(P值均<0.01).与对照组相比,SGC-7901细胞G0/G1期细胞明显增加[(56.67±1.18)%比(74.53±2.49)%,P<0.01],细胞增殖指数(PI)明显降低[(43.33±1.18)%比(25.50±2.46)%,P<0.01].随SAM浓度增加,SGC-7901细胞c-myc和uPA基因及MKN-45细胞的uPA基因mRNA表达明显减弱(P值分别<0.05和<0.01),经SAM 4mmol/L处理的MKN-28细胞的uPA基因mRNA表达亦明显减弱(P<0.01).经SAM处理的SGC-7901细胞c-myc基因和3种细胞的uPA基因均部分甲基化或完全甲基化.结论 SAM可通过逆转SGC-7901细胞c-myc基因和3种细胞uPA基因的低甲基化状态,从而调控基因的表达,并可通过提供甲基,改善基因的低甲基化状态,达到抑制胃癌细胞生长、增殖和侵袭的作用.     

5-氮杂-2′-脱氧胞苷通过上调法尼酯X受体启动子甲基化水平抑制HepG2细胞载脂蛋白A表达

目的 探索5-氮杂-2′-脱氧胞苷（5-Aza-CdR）的DNA去甲基化作用对HepG2细胞载脂蛋白A（ApoA）表达的影响,并探讨其作用机制。方法 选取ApoA高表达细胞株HepG2细胞为研究对象。噻唑蓝法测定HepG2经不同浓度（0、10、20、40、80 μmol/L）的5-Aza-CdR处理不同时间（12、24、48、72、96 h）后细胞相对存活率;Western blot检测5-Aza-CdR不同浓度组HepG2细胞ApoA、法尼酯X受体（FXR）的表达水平;逆转录聚合酶链反应检测ApoA、FXR的mRNA水平;亚硫酸氢盐测序PCR检测FXR基因启动子在5-Aza-CR不同浓度组的甲基化水平。结果 与对照组相比,5-Aza-CR 10、20、40 μmol/L组在12、24、48、72 h各组间细胞存活率无统计学差异（P>0.05）,而在20 μmol/L 96 h组、40 μmol/L 96 h组、80 μmol/L 24 h组、80 μmol/L 48 h组、80 μmol/L 72 h组以及80 μmol/L 96 h组HepG2细胞存活率存在统计学差异（P<0.05）,选取0～40 μmol/L为5-Aza-CdR的安全浓度范围,0～72 h为合适作用时间。与对照组相比,5-Aza-CdR呈剂量和时间依赖性上调FXR蛋白、下调ApoA蛋白表达,其中以40 μmol/L组最为明显（P<0.05）;与对照组相比,5-Aza-CdR呈剂量依赖性上调FXR mRNA、下调ApoA mRNA表达,其中以40 μmol/L组最为明显（P<0.05）。随着5-Aza-CdR浓度的递增,FXR基因启动子甲基化水平呈下降趋势,其中对照组FXR基因启动子甲基化率为58.3%,而40 μmol/L组FXR基因启动子甲基化率仅为8.3%。结论 5-Aza-CdR通过DNA去甲基化作用促进FXR表达,从而下调ApoA的表达。     

Liver cell adenoma and liver cell adenomatosis

During the last three decades liver cell adenoma and liver cell adenomatosis have emerged as new clinical entities in hepato-logical practice due to the widespread use of oral contraceptives and increased imaging of the liver. On review of published series there is evidence that 10% of liver cell adenomas progress to hepatocellular carcinoma, diagnosis is best made by open or laparoscopic excision biopsy, and the preferred treatment modality is resection of the liver cell adenoma to prevent bleeding and malignant transformation. In liver cell adenomatosis, the association with oral contraceptive use is not as high as in solitary liver cell adenomas. The risk of malignant transformation is not increased compared with solitary liver cell adenomas. Treatment consists of close monitoring and imaging, resection of superficially located, large (>4 cm) or growing liver cell adenomas. Liver transplantation is the last resort in case of substantive concern about malignant transformation or for large, painful adenomas in liver cell adenomatosis after treatment attempts by liver resection.     

Red cell exchange in sickle cell disease

Red cell exchange transfusion is frequently of use in the management of patients with sickle cell disease either electively or therapeutically. Modern cell separators allow this procedure to be performed rapidly, effectively and safely. These machines have a number of advantages over manual exchange procedures. The patient remains isovolaemic, there is little loss of plasma or platelets, the procedure is relatively short and in elective circumstances can be performed on an outpatient basis. In this series 66 exchanges were performed on 21 patients with an overall increase in HbA of 70%. The COBE Spectra gave a mean increase in HbA of 77%, with the majority of patients achieving an HbA of > 90% post exchange. Automated redcell exchange was well tolerated by most patients, and adverse effects were limited to symptoms of hypocalcaemia which were easily treated, and to transfusion reactions. Cell separators can therefore be recommended for exchange transfusion in patients with sickle cell disease, who require an increase in HbA levels either prophylactically or therapeutically. They are safe, effective, easy and quick to use.     

Erythrocyte-endothelial cell adherence in sickle cell disorders

Detachment of individual sickle erythrocytes from cultured endothelial cell monolayers has been evaluated by a fluid-shearing technique in an effort to quantitate adherence at shear forces that would be anticipated in the in vivo circulation. Nonirreversibly sickled cells (non-ISC) were more adherent at normal oxygen tensions than control cells. More than 1% non-ISC remained attached to the monolayer at forces greater than physiologic shear stresses in capillary and venous circulations, and many of the most avidly attached cells, once separated, immediately reattached to adjacent endothelial cells. These data suggest that hemoglobin S-containing erythrocytes may have a higher frequency of adherence in vivo in regions of low shear stress where prolonged erythrocyte-endothelial cell contact could occur. Some of these cells detached by shear force would subsequently reattach in in vivo conditions. Plasma-enhanced attachment frequency and plasma from blood in a case of sickle crisis caused further increase. These observations further support the concept that sickle erythrocyte- endothelial cell interaction may be a significant factor in initiation of vascular occlusive events in sickle cell disease.     

Actin filament debranching regulates cell polarity during cell migration and asymmetric cell division

The formation of the branched actin networks is essential for cell polarity, but it remains unclear how the debranching activity of actin filaments contributes to this process. Here, we showed that an evolutionarily conserved coronin family protein, the Caenorhabditis elegans POD-1, debranched the Arp2/3-nucleated actin filaments in vitro. By fluorescence live imaging analysis of the endogenous POD-1 protein, we found that POD-1 colocalized with Arp2/3 at the leading edge of the migrating C. elegans neuroblasts. Conditional mutations of POD-1 in neuroblasts caused aberrant actin assembly, disrupted cell polarity, and impaired cell migration. In C. elegans one-cell−stage embryos, POD-1 and Arp2/3, moved together during cell polarity establishment, and inhibition of POD-1 blocked Arp2/3 motility and affected the polarized cortical flow, leading to symmetric segregation of cell fate determinants. Together, these results indicate that F-actin debranching organizes actin network and cell polarity in migrating neuroblasts and asymmetrically dividing embryos.

Cell polarity is a fundamental feature of virtually all eukaryotic cells and plays crucial roles in a wide range of cellular processes, including cell motility, asymmetric cell division, and cell signaling (1). The establishment of cell polarity involves the asymmetric assembly of distinct cellular components to perform specialized functions. The actin-related protein (Arp) 2/3 complex-dependent branched actin networks and the pushing force they produce provide the principal means for cells to remodel the plasma membrane during cellular polarization (2). For example, in the leading edge of a migrating cell, the local Arp2/3-nucleated actin polymerization powers asymmetric projections of the plasma membrane (3). During asymmetric cell division of the Caenorhabditis elegans zygote, an actomyosin flow is central to the transport of the polarity PAR proteins into defined subcellular domains (4).Actin filaments'' continuous assembly must be balanced by actin depolymerization to ensure a constant supply of actin monomers for new growth. The Arp2/3 complex potency in actin nucleation empowers this complex as an essential regulator to organize the actin cytoskeleton. While Arp2/3 by itself is biochemically inactive, interactions with nucleation-promoting factors (NPFs) such as the Wiskott Aldrich syndrome protein (WASP)/WASP family verproline-homologous (WASP/WAVE) family proteins shift the Arp2/3 complex from its open, inactive conformation to a closed, active conformation (5, 6). The conformationally activated Arp2/3 complex then binds to the side of preexisting actin filaments to nucleate a branch from the mother filament (7–12). Conversely, nucleation by Arp2/3 can be inhibited by several binding partners, including glia maturation factor (GMF), Gadkin, Arpin, and Coronin, whose activities replenish available pools of actin monomers and Arp2/3 complexes for sustained actin assembly (13–18).The coronin family proteins are conserved actin regulators (19). The phylogenetic analysis grouped coronin genes into three types (19, 20). The best-characterized coronin is the Type I coronin (e.g., Coronin 1B) that binds to actin filaments through the β-propeller structure and to the Arp2/3 complex via its N terminus. These interactions block the docking of Arp2/3 onto actin filaments or facilitate debranching the existing actin network (20). Coronin 1B simultaneously interacts with the Slingshot phosphatase to dephosphorylate and activate ADF/Cofilin proteins that sever actin filaments, thereby promoting the actin network disassembly (13). Despite significant progress on Type I coronin, the activity and function of other coronins remain unclear. In particular, Type III coronins, known as POD-1 in C. elegans and Drosophila or Coronin7 in Dictyostelium and humans, contain two tandem coronin repeats, making them distinct from other coronins (19–21). POD-1 was biochemically isolated from C. elegans oocytes (22), and its mutations disrupted the polarity and architecture in early C. elegans embryos and impaired midlife touch sensitivity of the nematode (21, 23). However, it remains unclear how the Type III coronin functions. The Drosophila homolog of POD-1 is required for correct axon guidance, and the purified Dpod-1 cross-links the actin and microtubule cytoskeletons (24), whereas the mammalian Coronin7 was implicated in the Golgi morphology and function (25, 26), demonstrating the functional divergence of this family of coronin. Here, we show that the C. elegans POD-1 debranches Arp2/3-nucleated actin filaments in vitro and that POD-1 regulates cell polarity by remodeling the actin cytoskeleton during cell migration and asymmetric cell division.     

Red cell alloimmunization in sickle cell disease

Alloimmunization to red cell antigens contributes to morbidity in transfused patients. It has been recommended that blood for sickle cell patients need not be matched for antigens other than ABO and Rh(D), as there is no greater incidence of antibody production than in other multitransfused patient populations. Post transfusion alloimmunization was studied in a group of 34 sickle cell disease patients attending a U.K. haemoglobinopathy clinic. Red cell antibodies were formed in 17.6% of the transfused patients and Rhesus and Kell antibodies accounted for 66% of this total. In order to reduce alloimmunization, a policy of performing extended red cell phenotyping on the patients, and providing blood matched for Kell, and in certain circumstances the Rhesus antigens other than Rh(D), is recommended.     

Misdiagnosis of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (RCC) represents the most common histological subtype of malignant kidney tumors. Based on symptoms alone, clear cell RCC is indistinguishable from other histological classes of RCC unless the tumor is present in the context of an RCC syndrome. Histopathological examination is, therefore, important to accurately identify clear cell RCC. Clear cell RCCs have characteristic morphological criteria; these tumors can be easily identified upon typical presentation, but diagnosis can be challenging when tumor cell pattern is unusual or when availability of tissue samples is limited. In this Review, the clinical, radiological and pathological characteristics of clear cell RCCs are described, as well as the potential tumors that can be confused with clear cell RCC and need to be considered in the differential diagnoses. Finally, the importance of an accurate diagnosis is highlighted in the context of the increasing use of preoperative tissue sampling and the prevalence of clear cell tumors associated with hereditary syndromes, which could have different therapeutic and prognostic implications for patients and their families.     

Mechanism of red blood cell aging: Relationship of cell density and cell age

The human red cell has a life span of 120 days. The mechanism that determines cell removal from the circulation with such precision remains unknown. Most studies of red cell aging have been based on analysis of cells of progressively increasing age separated by density. The relationship between red cell age and density has been recently challenged, and the hypothesis has been put forward that cell death is not the result of a progressive deterioration of essential cell constituents. This theory was based on preliminary observations in transient erythroblastopenia of childhood, which could not later be confirmed. When the relationship between cell aging and increasing density is critically reviewed, it appears to be based on firm experimental evidence, confirmed by in vivo demonstration of decreasing survival of cells of increasing age. Analysis of studies using buoyant density gradients reveals that this technique can easily distinguish the single exponential slope of decline for those cell components that change progressively throughout the red cell life span from the biphasic decline of those that decrease drastically at the reticulocyte-mature red cell transition. The view that the aging of the red cell and its removal from the circulation result from a progressive series of events during the 120 days of its life span appears to be the most consistent with the available data. Density separation, validated by much experimental evidence, remains a most useful technique for the study of the mechanism of aging of the red cell. © 1993 Wiley-Liss, Inc.     

Automated red cell exchange in sickle cell disease

We used multiple optical trapping to study the mechanism of red cell (dis)aggregation. Two sets of optical 'tweezers' were used to bring two red blood cells together to form a two-cell aggregate and then to pull them apart, to study the interaction between the cells.
We found that cross-bridging occurred in normal reversible aggregation as we observed binding and the occurrence of small tethers between opposite cell membranes. Furthermore, the cells could only be parted by sliding them side by side with a maximum velocity in the order of μm/s indicating accumulation of the cross-bridges.     

Sphere-forming cell subpopulations with cancer stem cell properties in human hepatoma cell lines

Background

Cancer stem cells (CSCs) are regarded as the cause of tumor formation and recurrence. The isolation and identification of CSCs could help to develop novel therapeutic strategies specifically targeting CSCs.

Methods

Human hepatoma cell lines were plated in stem cell conditioned culture system allowed for sphere forming. To evaluate the stemness characteristics of spheres, the self-renewal, proliferation, chemoresistance, tumorigenicity of the PLC/PRF/5 sphere-forming cells, and the expression levels of stem cell related proteins in the PLC/PRF/5 sphere-forming cells were assessed, comparing with the parental cells. The stem cell RT-PCR array was performed to further explore the biological properties of liver CSCs.

Results

The PLC/PRF/5, MHCC97H and HepG2 cells could form clonal nonadherent 3-D spheres and be serially passaged. The PLC/PRF/5 sphere-forming cells possessed a key criteria that define CSCs: persistent self-renewal, extensive proliferation, drug resistance, overexpression of liver CSCs related proteins (Oct3/4, OV6, EpCAM, CD133 and CD44). Even 500 sphere-forming cells were able to form tumors in NOD/SCID mice, and the tumor initiating capability was not decreased when spheres were passaged. Besides, downstream proteins DTX1 and Ep300 of the CSL (CBF1 in humans, Suppressor of hairless in Drosophila and LAG1 in C. elegans) -independent Notch signaling pathway were highly expressed in the spheres, and a gamma-secretase inhibitor MRK003 could significantly inhibit the sphere formation ability.

Conclusions

Nonadherent tumor spheres from hepatoma cell lines cultured in stem cell conditioned medium possess liver CSC properties, and the CSL-independent Notch signaling pathway may play a role in liver CSCs.     

胆红素对肝星状细胞-T6增殖及细胞周期的影响

[目的]观察胆红素对肝星状细胞(HSC)-T6增殖及细胞周期影响.[方法]将培养细胞分成正常组和胆红素不同浓度(10 μmol/L、30 umol/L、50 /μmol/L、70 μmol/L、100 μmol/L)干预组,采用MTT法观察胆红素对HSC-T6增殖的影响,流式细胞仪观察各组细胞周期的变化.[结果]①不同浓度胆红素对HSC-T6均有促进增殖作用,且呈一定的量效关系,与正常组比较差异有统计学意义(P＜0.05);②10 μmol/L、50 μmol/L、100 μmol/L浓度胆红素作用HSC-T6后,G0/G1期减少,S期增加,G2/M期增加,与正常组比较均P＜0.05.[结论]胆红素对HSC-T6均有促进增殖作用.