植物细胞骨架与细胞生长

文章就微管和肌动蛋白在植物细胞生长中的调节作用以及调节植物细胞骨架的信号途径的研究进展作简单介绍。     

Circulating Tumor Cell Composition in Renal Cell Carcinoma

PurposeDue to their minimal-invasive yet potentially current character circulating tumor cells (CTC) might be useful as a “liquid biopsy” in solid tumors. However, successful application in metastatic renal cell carcinoma (mRCC) has been very limited so far. High plasticity and heterogeneity of CTC morphology challenges currently available enrichment and detection techniques with EpCAM as the usual surface marker being underrepresented in mRCC. We recently described a method that enables us to identify and characterize non-hematopoietic cells in the peripheral blood stream with varying characteristics and define CTC subgroups that distinctly associate to clinical parameters. With this pilot study we wanted to scrutinize feasibility of this approach and its potential usage in clinical studies.ResultsWe detected CTC with epithelial, mesenchymal, stem cell-like or mixed-cell characteristics at different time-points during anti-angiogenic therapy. The presence and quantity of N-cadherin-positive or CD133-positive CTC was associated with inferior PFS. There was an inverse correlation between high expression of HIF1A, VEGFA, VEGFR and FGFR and the presence of N-cadherin-positive and CD133-positive CTC.ConclusionsPatients with mRCC exhibit distinct CTC profiles that may implicate differences in therapeutic outcome. Prospective evaluation of phenotypic and genetic CTC profiling as prognostic and predictive biomarker in mRCC is warranted.     

Squamous Cell Differentiation in a Clonal Teratocarcinoma Cell Line

Several clonal teratocarcinoma cell lines restricted to squamous cell differentiation have been established from a subculture of totipotential murine teratocarcinoma stem cells. These lines contain a continuum of cell types from less differentiated precursor cells to differentiated squamous cells. In contrast to their highly malignant progenitors, these cells are nontumorigenic. Chromosomally, the cells are near-tetraploid, and their DNA distributions are tetraploid. These cell lines may prove useful in the study of normal squamous cell differentiation and also will be important in studies concerning the conversion of malignant cells to non-malignant progeny.     

Ion Channels in Cell Proliferation and Apoptotic Cell Death

Cell proliferation and apoptosis are paralleled by altered regulation of ion channels that play an active part in the signaling of those fundamental cellular mechanisms. Cell proliferation must - at some time point - increase cell volume and apoptosis is typically paralleled by cell shrinkage. Cell volume changes require the participation of ion transport across the cell membrane, including appropriate activity of Cl⁻ and K⁺ channels. Besides regulating cytosolic Cl⁻ activity, osmolyte flux and, thus, cell volume, most Cl⁻ channels allow HCO₃⁻ exit and cytosolic acidification, which inhibits cell proliferation and favors apoptosis. K⁺ exit through K⁺ channels may decrease intracellular K⁺ concentration, which in turn favors apoptotic cell death. K⁺ channel activity further maintains the cell membrane potential, a critical determinant of Ca²⁺ entry through Ca²⁺ channels. Cytosolic Ca²⁺ may trigger mechanisms required for cell proliferation and stimulate enzymes executing apoptosis. The switch between cell proliferation and apoptosis apparently depends on the magnitude and temporal organization of Ca²⁺ entry and on the functional state of the cell. Due to complex interaction with other signaling pathways, a given ion channel may play a dual role in both cell proliferation and apoptosis. Thus, specific ion channel blockers may abrogate both fundamental cellular mechanisms, depending on cell type, regulatory environment and condition of the cell. Clearly, considerable further experimental effort is required to fully understand the complex interplay between ion channels, cell proliferation and apoptosis.     

单细胞技术在干细胞研究中的应用

干细胞是具有自我更新和分化潜能的异质性细胞群体。基于细胞群体水平的干细胞研究不能满足深入认识干细胞生物学本质及实际应用的需要。近年来,单细胞相关技术不断发展和成熟,并正在干细胞基础研究及其相关领域中获得迅速应用。该文以造血干细胞为主要例举,就实验研究中常用的单细胞分离、单细胞克隆分析、单细胞移植、单细胞实时定量PCR及单细胞测序等技术原理及其应用进行综述。     

哺乳动物体细胞核移植中供体细胞的研究进展

在哺乳动物体细胞核移植中,供体细胞是影响其效率的主要因素之一。供体细胞的类型、细胞周期、细胞的培养代数、冷藏与冷冻处理,以及供体动物的性别、年龄等都可能影响核移植胚胎的发育。根据现有资料,简要综述了在哺乳动物体细胞核移植中有关供体细胞的研究进展。     

Role of Cell Wall-degrading Enzymes in Auxin-induced Cell Expansion in Yeast

Using auxin-responsive diploid strains of Saccharomyces cerevisiae and S. ellipsoideus, we studied the role of cell wall-degrading enzymes in the auxin-induced cell expansion. Highly purified fungal β-l,3-glucanase added to cell suspension caused cell expansion in these strains. The cell expansion induced by auxin was inhibited by the addition of õ-glucono-lactone, which inhibited the activity of a crude β-l,3-gluca-nase preparation from yeast in a competitive manner. Laminarinase activity was significantly higher in the extract from auxin-treated yeast cells than in the extract of cells not treated with auxin. These results support the idea that auxin induces expansion of yeast cells of certain strains through enhancement of the activity of wall polysaccharide-degrading enzymes.     

Formation of Interfamilial Cell Symplast During Cell Co-Culture in Vitro

Two cell lines, white tobacco (Nicotiana tabacum) cell line and green carrot (Daucus carota) cell line, each with very distinct cellular structure markers by which the two cell lines could be identified at levels of callus cells, with light microscopy and electron microscopy, were established and used for interfamilial cell co-culture in which callus cells were well mixed and finely dispersed and treated with K+ hypotonic solution. Variegated interfamilial chimeral calli were observed after 10 to 15 days of co-culture. An isolation layer was formed and became thickened at the interface between the two attached unrelated callus cells and the heteroplastic cell wall complex was gradually established. Then the isolation layer became thinned and disappeared and plasmodesmata were formed secondarily within the thinned region and the interfamilial cell symplast was established. The wall in the region with isolation layer was about twice as thick as the fused cell wall of the symplastic. The developmental process of the interfamilial cell symplastic connection was discussed and it was suggested that (1) the nonspecific formation of isolation layer as initial adhesion between the two attached unrelated cells was the prerequisit for symplastic connection de novo formation, and (2) the specific cell recognition leading to disappearance or thickening to lignification or suberization of isolation layer and formation of plasmodesmata started within the isolation layer.     

动物细胞培养过程中的细胞凋亡

细胞培养过程中的细胞凋亡是细胞受环境因素的影响而发生的现象。随着对细胞凋亡的分子生物学和细胞生物学了解的深入,显示了有效地控制动物细胞培养中细胞凋亡的巨大潜力。包括采用ＤＮＡ重组技术把抗细胞凋亡的基因导入细胞和在培基中加入具有抗细胞凋亡的生存因子或化合物等手段已用于控制细胞培养过程中的细胞凋亡。这些技术将大大延长细胞达到饱和密度后的培养时间,提高细胞培养系统的生产效率。     

细胞壁在细胞极性建立和胚胎发生中的作用

植物细胞壁是一个活性的动态结构,其结构层次与组分随着发育进程而发生变化,且广泛参与细胞的各项生命活动,特别是在参与细胞命运决定、充当细胞发育信使、调控植物胚胎早期极性建立以及模式建成等方面发挥重要作用。     

Addressing the Role of Cell Adhesion in Tumor Cell Dormancy

The dissemination of tumor cells prior to the surgical resection of early stage tumors poses a serious risk to the disease free survival of cancer patients. This risk arises from the latent capacity of these cells to form solid metastatic lesions after a prolonged period of dormancy, exacerbated by the fact that these cells are often refractory to adjuvant chemotherapeutic protocols. Ensuring the long term survival of cancer patients therefore necessitates an understanding of the mechanisms of tumor cell dormancy and the accompanying drug resistance. Experiments designed to compare the biological behavior of metastatic versus non-metastatic variants of tumor cells provide evidence that there exists a phenomenon of single-cell dormancy which may depend on a reciprocal dialogue between the tumor cell and the tissue microenvironment. Through a combination of 3-dimensional cell culture technique and in vivo models investigators are now beginning to elucidate the molecular mechanisms underlying this phenomenon. Here we review the results of a series of experiments describing the role of cell adhesion events in dictating tumor cell behavior, including the balance between proliferation and dormancy, and the acquisition of drug resistance.     

颌下腺导管细胞与胶原海绵细胞相容性的实验研究

为探讨胶原海绵对颌下腺 (submandibulargland ,SMG)导管细胞的细胞相容性 ,采用HE染色光镜观察及免疫组化观察SMG导管细胞接种于胶原海绵后 ,细胞的生长情况。光镜下可见接种后第 1d细胞数量较少 ,分散于胶原海绵支架中间 ,第 7d细胞数量明显增加 ,免疫组织化学染色抗IV型胶原抗体染色呈阳性 ,说明细胞与支架材料之间已经有细胞外基质产生。胶原海绵具有良好的细胞相容性 ,是一种理想的支架材料。与胶原海绵复合培养 ,颌下腺导管细胞仍可保持良好的增殖能力。     

Cytoplasmic Nucleoids in the Generative Cell,Sperm Cell and Egg Cell of Calystegia heder acea

Cytoplasmic nucleoids in the generative cell of mature pollens, sperm cells of pollens cultured in vitro and egg cell of mature embryo sac in Calystegia bederacea Wall. were studied by means of the DNA fluorochrome DAPI in conjunction with epitluorescence microscopy for in situ detection of cytoplasmic DNA in cells. Results showed that many cytoplasmic DNA nucleoids were present in the generative cell and speim cells. Two types of nucleoids were observed, one with big and strong fluorescent dots, and the other with small and weak fluorescence. Many dot-shaped and a few circle-shaped nucleoids were randomly distributed in the thin layered cytoplasm of the egg cell. It was suggested that different types of nucleoids might represent plastid DNA and mitochondrion DNA respectively. Results provided cytological data that Calystegia hederaeea had the potential of plastid DNA biparental inheritance, and the mode of which merits further study via molecular biological methods.     

Cancer Stem Cell-Like Side Population Cells in Clear Cell Renal Cell Carcinoma Cell Line 769P

Although cancers are widely considered to be maintained by stem cells, the existence of stem cells in renal cell carcinoma (RCC) has seldom been reported, in part due to the lack of unique surface markers. We here identified cancer stem cell-like cells with side population (SP) phenotype in five human RCC cell lines. Flow cytometry analysis revealed that 769P, a human clear cell RCC cell line, contained the largest amount of SP cells as compared with other four cell lines. These 769P SP cells possessed characteristics of proliferation, self-renewal, and differentiation, as well as strong resistance to chemotherapy and radiotherapy that were possibly related to the ABCB1 transporter. In vivo experiments with serial tumor transplantation in mice also showed that 769P SP cells formed tumors in NOD/SCID mice. Taken together, these results indicate that 769P SP cells have the properties of cancer stem cells, which may play important roles in tumorigenesis and therapy-resistance of RCC.