青蒿素及其衍生物的抗肿瘤机制

恶性肿瘤是严重威胁人类健康的重大疾病。尽管治疗手段不断发展,但推广度及疗效仍极为有限。新近研究发现,经典抗疟一线药青蒿素及其衍生物具有广泛抗肿瘤活性。大量研究提示,青蒿素及其衍生物通过细胞毒性效应直接杀死肿瘤细胞,也可诱导细胞周期阻滞从而抑制细胞增殖。另一方面,可通过凋亡、自噬、铁死亡途径导致细胞死亡。还可调控肿瘤微环境,从而抑制肿瘤细胞侵袭与转移。然而,尽管青蒿素及其衍生物展现出强大的抗肿瘤潜能,但其作用机制仍十分复杂。本文就青蒿素及其衍生物的抗肿瘤机制及其研究进展作一综述。     

Computational modelling and analysis of mechanical conditions on cell locomotion and cell–cell interaction

Between other parameters, cell migration is partially guided by the mechanical properties of its substrate. Although many experimental works have been developed to understand the effect of substrate mechanical properties on cell migration, accurate 3D cell locomotion models have not been presented yet. In this paper, we present a novel 3D model for cells migration. In the presented model, we assume that a cell follows two main processes: in the first process, it senses its interface with the substrate to determine the migration direction and in the second process, it exerts subsequent forces to move. In the presented model, cell traction forces are considered to depend on cell internal deformation during the sensing step. A random protrusion force is also considered which may change cell migration direction and/or speed. The presented model was applied for many cases of migration of the cells. The obtained results show high agreement with the available experimental and numerical data.     

HMBA诱导人肝癌SMMC-7721 细胞分化过程中 Nucleophosmin 的表达与定位变化

通过选择性抽提经环六亚甲基双乙酰胺（hexamethylene bisacetamide,HMBA）诱导处理前后的人肝癌SMMC-7721细胞核基质,并运用亚细胞蛋白质组学等分析技术,研究nucleophosmin (NPM)在核基质上的表达和定位变化,及其与相关基因产物的共定位关系,观察研究了nucleophosmin 在诱导分化前后人肝癌SMMC-7721细胞核基质中的存在、分布及其与相关基因产物的共定位关系.双向凝胶电泳和质谱鉴定结果显示,nucleophosmin 存在于 SMMC-7721 细胞核基质蛋白组分中,在 HMBA 处理后细胞核基质中表达下调.蛋白质印迹杂交实验结果确证了 nucleophosmin 在核基质中的存在及其在诱导处理后细胞核基质中表达下调的变化.免疫荧光显微镜观察显示,nucleophosmin 定位在 SMMC-7721细胞核基质上,经 HMBA处理后出现分布位置与表达水平的变化.激光扫描共聚焦显微镜观察结果显示,SMMC-7721细胞中,nucleophosmin与 c-fos、c-myc、rb、p53 等基因产物具有共定位关系,但在诱导处理后细胞内的共定位区域发生了改变.研究结果证实,nucleophosmin 是一种核基质蛋白,定位于核基质纤维上,nucleophosmin 在人肝癌 SMMC-7721 细胞诱导分化过程中的表达分布,及其与相关癌基因、抑癌基因产物的关系对 SMMC-7721 细胞分化具有重要影响.     

骨桥蛋白对细胞生存的多重作用

骨桥蛋白(osteopontin, OPN)作为一种分泌性蛋白质广泛存在于多种组织细胞中,不仅调控肿瘤细胞的转移、侵袭和增殖,也在炎症反应、血管再生等生理过程中发挥作用。OPN通过与受体结合直接或间接地激活细胞内信号途径,介导细胞与细胞、细胞与细胞外基质之间的相互作用,从而参与调控细胞的生存。大量实验证实,OPN能够促进细胞的增殖,抑制细胞凋亡,尤其是对于肿瘤细胞。但在有些细胞中,OPN对细胞命运的影响却恰恰相反。本文综述了OPN在不同条件下对细胞存活、活化和增殖,细胞自噬和细胞凋亡的多重作用及其作用途径,为进一步研究OPN对不同细胞作用的受体及其信号网络机制提供重要理论基础。     

超正电荷绿荧光蛋白+36GFP作为核酸载体的细胞穿透性分析

旨在通过原核表达纯化超正电荷绿色荧光蛋白+36GFP,研究其与核酸的结合作用及作为核酸载体的细胞转导功能。将pET+36GFP-HA2质粒转化到大肠杆菌BL21(DE3)菌株中,然后表达纯化+36GFP蛋白。将得到的目的蛋白在特定浓度下分别转导293细胞、HepG2细胞、A549细胞和B16细胞,流式细胞仪检测+36GFP的转导效率;+36GFP蛋白(100 nmol/L)转导A549细胞,激光共聚焦显微镜观察结果;将+36GFP蛋白与质粒DNA按不同比例孵育,凝胶阻滞实验检测+36GFP与DNA的结合能力;激光共聚焦显微镜和流式细胞仪检测+36GFP蛋白携带质粒DNA转导细胞后报告基因的表达。结果显示,+36GFP蛋白具有较高的细胞转导效率,且随浓度升高转导效率增加,呈浓度依赖性。凝胶阻滞实验显示,+36GFP能够与质粒DNA结合,阻滞DNA在凝胶中迁移,且呈现一定的浓度依赖性。+36GFP包裹质粒转导细胞后,可高效携带质粒DNA转导进入细胞,使质粒报告基因得到表达。本研究成功表达纯化了+36GFP蛋白,证实该蛋白具有较高的细胞转导效率,可将外源核酸携带入细胞使外源基因得到表达。     

Stimulation of endothelial cell migration in culture by ladsin,a laminin-5-like cell adhesion protein

Summary Ladsin is a laminin-like cell-adhesive scatter factor with potent cell motility-stimulating ability and was purified from serum-free conditioned medium of a malignant human gastric adenocarcinoma cell line STKM-1. To test its possible role in tumor angiogenesis, we investigated its effect on primary culture of endothelial cells (human umbilical vein endothelial cells) and endothelial cell line ECV304 in this study. Cell adhesion and motility effects of ladsin were observed in both types of endothelial cells. In cell-attachment assay, ladsin interacted with integrin α3β1 that was expressed on the endothelial cell surface. In Boyden chambers, ladsin stimulated both directed and random migration of ECV304 cells. Ladsin induced repair of artificial wounds generated in ECV304 cell monolayers by stimulating cell migration. Ladsin did not affect the growth rate of ECV304 cells at a low cell density but significantly increased the saturation cell density. These results suggest that ladsin may be involved in the adhesion and migration of endothelial cells under some physiological and pathological conditions.     

单细胞转录组技术及其在人类细胞图谱构建中的应用

单细胞转录组技术在单细胞水平上进行转录组测序,提供了单个细胞的基因表达差异信息,使在单细胞尺度下研究个体细胞、相关环境细胞及其相互作用的机理成为可能.近年来,单细胞转录组技术在c DNA扩增原理上经历了从末端加尾、体外逆转录到模板置换的方法发展,大大提高了基因检测的数量、基因表达的准确性等.同时,在单细胞选取方式上进行了从96/384孔板到油包水液滴以及纳米微孔的创新,在提高通量和重复性的同时降低了整体实验成本.单细胞转录组技术广泛应用于细胞群体分类和异质性研究,推动了从发育生物学到正常、病态组织细胞图谱的构建.本文对单细胞转录组技术近年的技术进展以及在人类细胞图谱构建中的应用进行了综述.     

RTN4-C基因在肝癌组织中的表达及其对SMMC7721细胞生长和凋亡的影响

RTN4-C属于编码内质网蛋白的基因家族(RTNs)。为研究RTN4-C在肝癌及其癌旁组织中的表达情况及其对SMMC7721肝癌细胞株的影响,利用RT-PCR检测RTN4-C在肝癌及其癌旁组织中的表达。构建RTN4-C-pcDNA3.1真核表达重组质粒,用脂质体介导转染SMMC7721肝癌细胞,通过G418稳定筛选,建立转染RTN4-C/SMMC7721稳定细胞株。MTT法测定转染前后细胞生长改变、吖啶橙染色检测细胞凋亡改变、免疫细胞化学检测肿瘤相关蛋白p53、Hsp70和c-Fos表达改变。结果表明,RTN4-C/SMMC7721细胞生长减慢,与对照组相比,第2、3、4d细胞生长抑制率分别为33·8%±0·026、56·2%±0·094、34·8%±0·077;凋亡明显增多。突变型p53蛋白从核内转移到细胞质且表达减弱,c-Fos、Hsp70蛋白表达量明显减弱。提示RTN4-C基因在肝癌组织中存在表达差异,促进突变型p53的核转移并减少其表达量、抑制癌基因c-Fos和Hsp70的表达,从而抑制SMMC7721细胞的生长,促进其凋亡。     

Polo样激酶1在细胞周期及细胞周期监测点中的功能

Plk1（Polo-like kinase 1）是一类从酵母到人类都高度保守的丝氨酸/苏氨酸蛋白激酶,是真核细胞有丝分裂的重要调控因子.Plk1随有丝分裂进程定位于不同位点,调节分裂期进入、纺锤体形成和胞质分裂等过程.Plk1能够与磷酸化的停靠蛋白结合,从而在不同空间被激活以满足其在细胞周期中的不同功能.Plk1还参与G2和M期DNA损伤监测点的调节,对于DNA损伤恢复后重新进入有丝分裂期是必须的.目前,Plk1的重要功能尤其是在DNA损伤监测点中发挥的重要功能正在被广泛研究.Plk1在多种恶性肿瘤中存在过表达且与肿瘤发生密切相关,对于Plk1功能的深入研究为以Plk1为靶的肿瘤治疗提供理论依据     

Cell cross-contamination in cell cultures: The silent and neglected danger

Summary Cell cross-contamination in cell cultures is a common problem during cell culturing and use. Contamination invalidates research results, compromises the comparison of results between laboratories, reduces reproducibility required in industrial production of cell lines, and may lead to unusable therapeutic products. The problem can be solved by increasing the awareness of its seriousness and by introducing regular quality control of cell cross-contamination in every laboratory where cells are grown and used. The article presents only a personal opinion of the coauthor.     

The balancing act of AKT in T cells

The serine/threonine-specific protein kinase AKT is gaining recognition as a major crossroad in numerous cellular signaling pathways through its ability to regulate cell differentiation, proliferation, survival and metabolism. This review focuses on the recent advances in AKT signaling and downstream events in T cells, emphasizing its contrasting role in conventional and regulatory (Treg) Tcell populations. Activation of AKT has been known for many years to be critical in the development and function of conventional Tcells. However, it has just recently been uncovered that AKTexerts an inhibitory effect on Treg generation and suppressor function. These studies have placed AKTat the nexus of Treg development and function, thus opening novel avenues for therapeutic manipulation.     

关于干细胞临床产业化的一些思考

干细胞的基础研究和临床应用是近几年国内外的热点之一。但是因为没有产业化的明确途径,这个领域的产业化发展缓慢,很有可能像基因治疗和肿瘤疫苗的产业化一样无疾而终。本文探讨了干细胞治疗能够产业化之前需要解决的几个问题。从技术层面,我们比较了胚胎干细胞和成体干细胞,自体干细胞和异体干细胞的优缺点和国内外公司采取的一些途径。从政策方面,我们探讨了把干细胞治疗作为一种医疗技术还是一类医药产品的优缺点,比较了美国FDA和国内监管部门的相关政策,也提出了进一步的问题。最后,我们以美国FDA刚刚批准的Provenge为例,对细胞治疗和干细胞治疗的产业化提出了一些希望和想法。     

Mammalian testis: a target of in vivo electroporation

Mammalian spermatogenesis consists of three biologically significant processes: stem cell self-renewal and differentiation, meiosis, and haploid cell morphogenesis. Understanding the molecular mechanisms behind these processes might provide clues to the puzzle of species preservation and evolution, and to treatments for male infertility. However, few useful in vitro systems exist to investigate these processes at present. To elucidate these mechanisms, in vivo electroporation of the testis might be a convenient option. Since DNA solution can be injected into the seminiferous tubule via the rete testis, similar to germ cell transplantation, it is easy to transfect expression vectors into various differentiated germ cells and supporting Sertoli cells with adequate electric shock. Unfortunately, it is difficult to create transgenic animals using this method because of its low efficiency. However, gain- and loss-of-function assays, promoter assays, and tagged-protein behavior assays can be conducted with this technique, as in in vitro culture systems.     

Spatial and temporal coordination of traction forces in one-dimensional cell migration

ABSTRACT

Migration of a fibroblast along a collagen fiber can be regarded as cell locomotion in one-dimension (1D). In this process, a cell protrudes forward, forms a new adhesion, produces traction forces, and releases its rear adhesion in order to advance itself along a path. However, how a cell coordinates its adhesion formation, traction forces, and rear release in 1D migration is unclear. Here, we studied fibroblasts migrating along a line of microposts. We found that when the front of a cell protruded onto a new micropost, the traction force produced at its front increased steadily, but did so without a temporal correlation in the force at its rear. Instead, the force at the front coordinated with a decrease in force at the micropost behind the front. A similar correlation in traction forces also occurred at the rear of a cell, where a decrease in force due to adhesion detachment corresponded to an increase in force at the micropost ahead of the rear. Analysis with a bio-chemo-mechanical model for traction forces and adhesion dynamics indicated that the observed relationship between traction forces at the front and back of a cell is possible only when cellular elasticity is lower than the elasticity of the cellular environment.     

The p57 CDKi integrates stress signals into cell-cycle progression to promote cell survival upon stress

The p57(Kip2) cyclin-dependent kinase inhibitor (CDKi) has been implicated in embryogenesis, stem-cell senescence and pathologies, but little is known of its role in cell cycle control. Here, we show that p57(Kip2) is targeted by the p38 stress-activated protein kinase (SAPK). Phosphorylation of p57(Kip2) at T143 by p38 enhances its association with and inhibition of Cdk2, which results in cell-cycle delay upon stress. Genetic inactivation of the SAPK or the CDKi abolishes cell-cycle delay upon osmostress and results in decreased cell viability. Oxidative stress and ionomycin also induce p38-mediated phosphorylation of p57 and cells lacking p38 or p57 display reduced viability to these stresses. Therefore, cell survival to various stresses depends on p57 phosphorylation by p38 that inhibits CDK activity. Together, these findings provide a novel molecular mechanism by which cells can delay cell cycle progression to maximize cell survival upon stress.     

A Stat5-overlapping site is critical for the IgJ enhancer activity in the plasma cells and bound by a ubiquitous protein

Although the IgJ enhancer chromatin is induced open by an IL-2/Stat5 signaling during terminal B cell differentiation, the opened chromatin of IgJ enhancer is then maintained in the absence of IL-2/Stat5 signaling. Nevertheless, the sequence overlapping the Stat5 site was shown still to be essential for the function of IgJ enhancer in the plasma cells. An in vivo footprint was identified over the Stat5-overlapping site, indicating that the site should be bound by a certain other protein than Stat5. In EMSA using the Stat5-overlapping sequence as a probe, its specific binding protein was identified. The specific binding protein corresponded neither to any of other Stat family proteins, nor to any of potential candidate proteins as tested in EMSA using their corresponding oligo DNA competitors and antibodies. Although its identity remains to be found by its purification, the protein binding specifically to the Stat5-overlapping site was shown to be expressed rather ubiquitously in B and non-B cells, and its molecular weight appeared to be below 52 kDa as determined in the UV-crosslinking-coupled SDS-PAGE.     

Expression of kindlin-3 in melanoma cells impedes cell migration and metastasis

Kindlins are a small family of 4.1-ezrin-radixin-moesin (FERM)-containing cytoplasmic proteins. Kindlin-3 is expressed in platelets, hematopoietic cells, and endothelial cells. Kindlin-3 promotes integrin activation, clustering and outside-in signaling. Aberrant expression of kindlin-3 was reported in melanoma and breast cancer. Intriguingly, kindlin-3 has been reported to either positively or negatively regulate cancer cell metastasis. In this study, we sought to clarify the expression of kindlin-3 in melanoma cells and its role in melanoma metastasis. Two widely used metastatic mouse and human melanoma cell lines B16-F10 and M10, respectively, were examined and found to lack kindlin-3 mRNA and protein expression. When kindlin-3 was ectopically expressed in these cells, cell migration was markedly reduced. These are attributed to aberrant Rac1 and RhoA activation and overt membrane ruffling. Our data demonstrate for the first time that despite its well established role as a positive regulator of integrin-mediated cell adhesion, aberrant expression of kindlin-3 could lead to imbalanced RhoGTPases signaling that impedes rather than promotes cell migration.     

细丝蛋白A在细胞黏附和迁移中的作用

细胞迁移在发育、伤口愈合、炎症反应和肿瘤转移等多种病理生理过程中发挥重要作用。细丝蛋白A（filamin A,FlnA）是一种在各组织细胞中广泛表达的微丝结合蛋白,其表达异常导致细胞迁移功能障碍。该文回顾了相关的文献,首先介绍生理情况下细丝蛋白A的功能,接着介绍细丝蛋白A基因突变和表达异常导致的多种遗传性疾病及其与肿瘤转移的关系,突出细丝蛋白A对迁移的影响在这些疾病发病中的作用,最后深入探讨了细丝蛋白A影响细胞迁移和黏附的可能机制。