乳腺癌干细胞分选及相关信号通路研究进展

肿瘤干细胞是指存在于肿瘤组织中的具有干细胞特性,即能够多向分化和自我更新的一类细胞群。随着肿瘤干细胞概念的提出,乳腺癌干细胞成为当今科研领域的一个研究热点。因此,了解如何分选乳腺癌干细胞及如何维持其"干性"对治疗及预防乳腺癌具有至关重要的意义。主要从乳腺癌干细胞分选、相关信号通路、上皮-间充质转换(EMT)等方面进行综述。     

斑马鱼胚胎发育中细胞凋亡的研究进展

细胞凋亡是细胞在基因调控下发生的主动消亡过程,在脊椎动物胚胎发育过程中非常重要。斑马鱼作为一种十分理想的发育分子生物学研究模型,在有关细胞凋亡在诸如形态发生、性别分化等方面功能之活体在位研究中日益受到重视。目前,斑马鱼胚胎发育中主要凋亡通路研究已进行了不少工作,特别是caspase及其它凋亡调控基因在斑马鱼中已被成功克隆,通过转基因斑马鱼胚胎中胁迫诱导细胞凋亡并研究其信号通路以及斑马鱼胚胎形态发生的异常改变,为阐明这些凋亡调控基因与发育之间的关系提供了一个强有力的手段。     

神经生长因子及其受体相关信号传导通路的研究进展

神经生长因子是神经营养因子家族成员之一,对不同时期神经元的存活、分化、生长及损伤后的修复和再生都有着十分重要的作用。不仅在神经系统中,随着人类的其他正常和肿瘤组织中同样也检测得到了NGF,神经生长因子在各方面的应用也得到了重视并均已得到了证实。NGF功能的发挥离不开与其受体的结合,根据NGF表面糖蛋白与凝集素结合能力的不同,其受体可被分为高亲和力受体酪氨酸激酶A和低亲和力受体p75。Trk A与NGF结合后所介导的信号通路主要有:1MAPK通路;2PLC-γ通路;3PI3K/PKB通路。而p75与NGF结合介导的信号传导通路主要包括:1NF-κB通路;2JNK-p53-Bax凋亡通路;3神经酰胺通路。Trk A一般介导的是正性信号,如促进神经细胞生长、维持神经细胞的存活等;而p75既可促进神经细胞存活,也可诱导神经细胞凋亡,但以后者为主。当Trk A与p75同时表达时,Trk A可抑制p75诱导细胞凋亡,使受损神经细胞大量增殖,所以其生物学总效应是促进神经细胞的生长和存活。     

调控纤连蛋白表达的信号通路

纤连蛋白(fibronectin,Fn)作为细胞外基质(extracellular matrix,ECM)中重要的黏附分子之一,通过与细胞膜上的整合素受体结合,在调节细胞黏附、迁移、增殖等过程中发挥着重要作用。Fn的异常表达与伤口愈合、肿瘤转移、组织器官纤维化等密切相关。Fn的表达受到复杂的细胞信号通路网络调控,其中包括MAPK、TGF-β1/Smad、PKC、JAK/STAT及JNK/NF-κB/NADPH/ROS等。该文对调控Fn表达的信号通路及分子作一综述,旨在全面了解Fn参与机体对环境变化的适应机制及与Fn表达异常相关疾病的分子机理。     

非洲绿猴层黏连蛋白受体的克隆、表达及纯化

目的:克隆、表达非洲绿猴层黏连蛋白受体(LR),对该受体蛋白进行纯化、复性研究。方法:采用RT-PCR从Vero-E6细胞总RNA中扩增非洲绿猴LR的cDNA序列,克隆到pGEM-TEasy载体上;将LR编码区插入到表达载体pET22b( ),转化大肠杆菌BL21(DE3);用IPTG进行诱导表达;用镍亲和柱进行亲和纯化;采用分部透析方法进行复性。结果:非洲绿猴LR基因序列与人LR的基因编码序列有16个碱基差异,但蛋白序列只有1个氨基酸的改变。LR蛋白以包涵体形式表达。采用分部透析方法可使部分蛋白得到复性。结论:克隆了首个非洲绿猴的相对分子质量为37000的LR的基因,与人LR基因序列有16个碱基差异,但其中15处都为同义突变,所以二者的蛋白质序列只有1个氨基酸改变,即293位D→E,提示LR在进化中具有很大的保守性。     

肺干细胞和肺癌干细胞研究进展

近年来成体干细胞研究进展迅速。肺干细胞和肺癌干细胞在表面标志、分离方法和功能研究等方面也取得了一定进展。在肺组织中,肺干细胞维持着肺上皮的更新和稳定,肺脏不同解剖结构存在不同的干细胞,主要的肺干细胞有气管—支气管干细胞、细支气管干细胞、细支气管肺泡干细胞和肺泡干细胞等,不同干细胞特异表面标志也不同。根据肿瘤干细胞理论,目前研究认为肺癌的发生与肺癌干细胞有关,肺癌干细胞来源于其对应肺干细胞的恶性转化。肺癌干细胞特异标志研究主要集中在侧群细胞、CD133和醛脱氢酶等。与其他成体干细胞相似,肺癌干细胞维持自我更新以及分化能力的信号通路主要有Wnt、Hedgehog和Notch通路等。肺癌干细胞与肺癌的发生、发展、转移、治疗反应及预后关系,也取得了一定的进展。该文对肺干细胞和肺癌干细胞研究进展作简要综述。     

成年哺乳动物神经发生的研究进展

神经干细胞是一类具有自我更新能力和多向分化潜能的干细胞。在特定条件下,神经干细胞可分化为神经元、少突胶质细胞和星形胶质细胞从而参与神经功能的修复过程,该过程称为神经发生。一直以来,人们认为神经发生主要发生在哺乳动物胚胎时期,而成体是不存在神经发生的。然而近年的研究表明,成体神经发生在哺乳动物中枢神经系统中是终生存在的,且通过多种信号通路来调控。现就成年哺乳动物神经发生的研究进展展开论述。     

慢病毒载体介导的层黏连蛋白受体稳定抑制细胞株的建立

目的:构建靶向层黏连蛋白受体(LR)基因的小发卡RNA(sh RNA)慢病毒表达载体,鉴定其对LR的抑制效果,并筛选LR稳定抑制的He La细胞株。方法:设计针对LR的sh RNA序列,将此序列和H1启动子克隆入含有EGFP报告基因的p Lenti6/v5慢病毒表达载体,通过病毒包装、细胞感染、抗生素筛选获得稳定细胞株,用real-time PCR和Western印迹检测筛选得到的稳定细胞株中LR的表达水平。结果和结论:构建了含有LR靶向sh RNA的慢病毒表达载体,包装成病毒后感染He La细胞,经抗生素筛选后获得了稳定抑制LR的细胞株;筛选后的细胞均可观察到报告基因EGFP的表达;经m RNA和蛋白水平检测,LR-sh6和LR-sh7均可显著抑制He La细胞株中LR的表达。     

抵抗素在胰岛素抵抗中的作用机制及其受体信号通路研究进展北大核心CSCD

抵抗素是近年来在体内发现的一种新的脂肪细胞因子。研究显示,抵抗素可以通过多种途径促发胰岛素抵抗,诱导2型糖尿病(type 2 diabetes mellitus,T2DM)的发生,并且可以经由不同的信号通路介导机体炎性反应。抵抗素作为联系炎症与代谢的信号因子,有望为治疗胰岛素抵抗和T2DM提供新思路。然而,由于尚未在体内找到抵抗素的特异性受体,其在体内一系列调节活动的具体机制目前仍不清楚。本文就目前关于抵抗素在胰岛素抵抗调节机制及其受体信号通路的研究进展作一综述。     

乳腺癌肿瘤干细胞的研究进展

干细胞(stem cell,SC)是一类具有自我更新、多向分化潜能的特殊细胞群体.而肿瘤干细胞(cancer stem cell,CSC)不仅具备了干细胞方面的特征,同时还有其自身特殊性.乳腺癌中肿瘤干细胞的发现为乳腺癌的治疗提供了创新性策略.近年来,有关乳腺癌肿瘤干细胞的筛选标记和方法以及信号转导通路方面的研究颇多,但其中也不乏争议.就乳腺癌干细胞研究的最新进展作一端述.     

Laminin α5 guides tissue patterning and organogenesis

Laminins (LM) are extracellular matrix molecules that contribute to and are required for the formation of basement membranes. They participate in the modulation of epithelial/mesenchymal interactions and are implicated in organogenesis and maintenance of organ homeostasis. Among the LM molecules, the LM α5 chain (LMα5) is one of the most widely distributed LM in the developing and mature organism. Its presence in some basement membranes during embryogenesis is absolutely required for maintenance of basement membrane integrity and thus for proper organogenesis. LMα5 also regulates the expression of genes important for major biological processes, in part by repressing or activating signaling pathways, depending upon the physiological context.     

Laminin-1 and epidermal growth factor family members co-stimulate fetal pancreas cell proliferation and colony formation

The epidermal growth factor (EGF) family is implicated in the development and function of multiple cells and organs, including the pancreas. We used a serum-free, low-cell density culture system to investigate the effect of EGFs on fetal pancreas cells. By RT-PCR, the EGF receptors ErbB 1-3 were detected in the developing mouse pancreas between embryonic day (E) 13.5 and E17.5, whereas ErbB4 was not detected until E17.5. The presence but not absence of the basement membrane glycoprotein laminin-1, betacellulin, and to a lesser extent EGF, transforming growth factor alpha, heparin binding EGF, and epiregulin induced E15.5 pancreatic cells to proliferate and form cystoid and solid colonies. These results demonstrate that laminin-1 and EGF signaling pathways interact to promote pancreas development.     

癌、干细胞和癌干细胞共同拥有的信号传导通路

干细胞（SC）是具有无限自我更新和分化能力的细胞,随着对SC研究的不断深入,人们发现SC与肿瘤细胞有许多共性,如无限增生能力、迁移能力及在某些条件下能相互转化,故提出了肿瘤起源于SC的学说。探讨癌、SC和癌干细胞（CSC）之间可能存在的共同信号传导通路,以便发现治疗CSC的靶位。     

Laminin-511 expression is associated with the functionality of feeder cells in human embryonic stem cell culture

Fibroblast feeder cells play an important role in supporting the derivation and long term culture of undifferentiated, pluripotent human embryonic stem cells (hESCs). The feeder cells secrete various growth factors and extracellular matrix (ECM) proteins into extracellular milieu. However, the roles of the feeder cell-secreted factors are largely unclear. Animal feeder cells and use of animal serum also make current feeder cell culture conditions unsuitable for derivation of clinical grade hESCs. We established xeno-free feeder cell lines using human serum (HS) and studied their function in hESC culture. While human foreskin fibroblast (hFF) feeder cells were clearly hESC supportive, none of the established xeno-free human dermal fibroblast (hDF) feeder cells were able to maintain undifferentiated hESC growth. The two fibroblast types were compared for their ECM protein synthesis, integrin receptor expression profiles and key growth factor secretion. We show that hESC supportive feeder cells produce laminin-511 and express laminin-binding integrins α3ß1, α6ß1 and α7ß1. These results indicate specific laminin isoforms and integrins in maintenance of hESC pluripotency in feeder-dependent cultures. In addition, several genes with a known or possible role for hESC pluripotency were differentially expressed in distinct feeder cells.     

Regulation effects of melatonin on bone marrow mesenchymal stem cell differentiation

Melatonin’s therapeutic potential has been highly underestimated because its biological functional roles are diverse and relevant mechanisms are complicated. Among the numerous biological activities of melatonin, its regulatory effects on pluripotent mesenchymal stem cells (MSCs), which are found in bone marrow stem cells (BMSCs) and adipose tissue (AD-MSC), have been recently proposed, which has received increasingly more attention in recent studies. Moreover, receptor-dependent and receptor-independent responses to melatonin are identified to occur in these cells by regulating signaling pathways, which drive the commitment and differentiation of MSCs into osteogenic, chondrogenic, or adipogenic lineages. Therefore, the aim of our current review is to summarize the evidence related to the utility of melatonin as a regulatory agent by focusing on its relationship with the differentiation of MSCs. In particular, we aimed to review its roles in promoting osteogenic and chondrogenic differentiation and the relevant signaling cascades involved. Also, the roles that melatonin and, particularly, its receptors play in these processes are highlighted.     

Laminin-5 immunocytochemistry: a new tool for identifying dysplastic cells in oral brush biopsies

BACKGROUND: The brush biopsy technique is not only a seminal technique but also a critically discussed method for detection of oral pre-cancerous stages and manifest carcinomas. The gamma2 chain of laminin-5 and its proteolytic fragments comprise an invasion factor for many carcinomas. OBJECTIVES: The aim of this study was to determine whether the immunocytochemical presentation of the laminin gamma2 chain identifies pre-invasive or invasive squamous cells in brush biopsies. METHODS: The value-based identification of atypical epithelia was analysed in 93 consecutive brush biopsies with histopathological diagnoses: standardized haematoxylin and eosin staining; standardized immunocytochemistry: monoclonal antibodies against laminin gamma2 chain: D4B5, 4G1, detection using ChemMate and Autostainer. RESULTS: Conventional cytology did not result in any false-positive cases, i.e. atypical cells in normal, inflamed or benignly hyperproliferative mucosa (specificity, 100%), whereas immunocytochemistry revealed one false-positive case (specificity, 98%). In brush biopsies of oral squamous cell carcinomas, the following immunocytochemical patterns were possible: (1) staining of the cytoplasm, (2) banded markings between clumped carcinoma cells and (3) positive hazes surrounding atypical cells. Bacterial colonies appeared as false-positive results. Four of 27 carcinomas and one of three recurrences were not cytologically identified (sensitivity of conventional cytology, 79%). Three of the five carcinomas not identified by cytology were immunocytochemically stained with laminin gamma2 chain antibody (sensitivity of laminin gamma2 chain immunocytochemistry, 93%). The positive predictive value was 100% for conventional cytology and 97% for laminin gamma2 chain immunocytochemistry. The negative predictive value attained was 92% for conventional cytology and 97% for laminin gamma2 chain immunocytochemistry. CONCLUSIONS: The high sensitivity level observed for method-enhanced brush cytology suggests that this technique be used as an initial diagnostic step.     

造血干细胞发育过程中的信号通路调控

血液系统是维持机体生命活动最重要的系统之一,为机体提供所需的氧气和营养物质,通过物质交换维持内环境的稳态,同时为机体提供免疫防御与保护。血细胞是血液的重要组成成分,机体中成熟血细胞类型起源于具有自我更新及分化潜能的多能成体干细胞—造血干细胞(hematopoietic stem cells,HSCs)。造血干细胞及各类血细胞产生、发育及成熟的过程称为造血过程,该过程开始于胚胎发育早期并贯穿整个生命过程,任一阶段出现异常都可能导致血液疾病的发生。因此,深入探究造血发育过程及其调控机制对于认识并治疗血液疾病至关重要。近年来,以小鼠(Mus musculus)和斑马鱼(Danio rerio)作为动物模型来研究造血发育取得了一系列的进展。其中,BMP、Notch和Wnt等信号通路对造血干细胞的命运决定和产生发挥了重要作用。本文对这些信号通路在小鼠和斑马鱼造血过程中的调控作用进行系统总结,以期能够完善造血发育过程的调控网络并为临床应用提供指导。     

褐色脂肪组织研究的最新进展和科学意义

哺乳动物体内存在着褐色脂肪组织。有别于白色脂肪组织储存能量的功能,褐色脂肪组织的主要功能是通过产热作用来维持机体的能量代谢平衡。陆续有研究阐明调控褐色脂肪组织分化与能量代谢过程的分子机制,逐渐揭示了褐色脂肪组织分化与能量代谢过程中涉及的信号通路与转录调控。这不仅让我们更好地理解褐色脂肪组织在能量代谢调控中的重要作用,而且为基于褐色脂肪组织的肥胖治疗提供了理论依据。本文阐述了近年来研究发现的褐色脂肪组织分化与代谢过程中发挥重要作用的信号通路与转录调控,并讨论了多种基于针对褐色脂肪组织的肥胖治疗手段的有效性与可行性。     

Toll-like receptors signaling in glomerular diseases

Abstract

Toll-like receptors (TLRs) are pattern-recognition receptors that recognize microbial/vial-derived components that trigger innate immune response, which indicate these molecules play a role in host defense against infection. The infection often precedes numerous disorders including glomerular diseases (glomerulonephritis (GN)). It is reported that TLRs are also involved in the risk and progression of GN, and TLRs may be potential therapeutic targets for GN. To date, a number of studies have found that TLRs are involved in the pathogenesis of GN. There is a paucity of reviews in the literature discussing signaling pathways and gene expression for TLRs in GN. This review was performed to provide a relatively complete signaling pathway flowchart for TLRs to the investigators who were interested in the roles of TLRs in the pathogenesis of GN. In the past decades, some studies were also performed to explore the association of TLRs gene expression with the risk of GN. However, the role of TLRs in the pathogenesis of GN remains controversial. Here, the signal transduction pathways of TLRs and its role of gene expression in the pathogenesis of GN were reviewed.     

Role of toll-like receptors in lung cancer

Abstract

Lung cancer is a leading cause of death world-wide and the long-term survival rate for patients with lung cancer is one of the lowest for any cancer. Toll-like receptors (TLRs), evolutionarily conserved innate, are expressed in a wide variety of tissues and cell types, and they play key role in the innate immune system. TLRs have been found to be expressed by some kinds of tumor cells. However, what is the biological function of TLRs on tumor cells and whether human lung cancer cells can express TLRs remain to be fully understood. This review was performed to sum up the role of TLRs in lung cancer.