干细胞相关基因Oct-4在人肿瘤细胞系中的表达及其意义

目的 探讨干细胞相关基因Oct-4在多种人肿瘤细胞系中的表达.方法 体外培养人胰腺癌、宫颈癌、肝癌、乳腺癌、结肠癌细胞系,应用RT-PCR和Western blot法分别检测Oct-4 mRNA和蛋白在各种人肿瘤细胞系中的表达.结果 Oct-4 mRNA和蛋白在胰腺癌细胞系SW1990、PANC1、BxPC3、PC3,宫颈癌细胞系HELA,肝癌细胞系HepG2,乳腺癌细胞系MCF-7和结肠癌细胞系CaCo2中均有表达.结论 干细胞相关基因Oct-4在肿瘤细胞中的表达,一方面说明恶性肿瘤与干细胞具有密切的关系,另一方面也说明Oct-4基因在这些肿瘤的发生中起到重要作用.     

干细胞相关基因Oct-4在人肿瘤细胞系中的表达及其意义

目的探讨干细胞相关基因Oct-4在多种人肿瘤细胞系中的表达。方法体外培养人胰腺癌、宫颈癌、肝癌、乳腺癌、结肠癌细胞系,应用RT-PCR和Western blot法分别检测Oct-4mRNA和蛋白在各种人肿瘤细胞系中的表达。结果Oct-4mRNA和蛋白在胰腺癌细胞系SW1990、PANC1、BxPC3、PC3,宫颈癌细胞系HELA,肝癌细胞系HepG2,乳腺癌细胞系MCF-7和结肠癌细胞系CaCo2中均有表达。结论干细胞相关基因Oct-4在肿瘤细胞中的表达,一方面说明恶性肿瘤与干细胞具有密切的关系,另一方面也说明Oct-4基因在这些肿瘤的发生中起到重要作用。     

A minimal cytoplasmic subdomain of the erythropoietin receptor mediates erythroid and megakaryocytic cell development.

Signals provided by the erythropoietin (Epo) receptor are essential for the development of red blood cells, and at least 15 distinct signaling factors are now known to assemble within activated Epo receptor complexes. Despite this intriguing complexity, recent investigations in cell lines and retrovirally transduced murine fetal liver cells suggest that most of these factors and signals may be functionally nonessential. To test this hypothesis in erythroid progenitor cells derived from adult tissues, a truncated Epo receptor chimera (EE372) was expressed in transgenic mice using a GATA-1 gene-derived vector, and its capacity to support colony-forming unit-erythroid proliferation and development was analyzed. Expression at physiological levels was confirmed in erythroid progenitor cells expanded ex vivo, and this EE372 chimera was observed to support mitogenesis and red blood cell development at wild-type efficiencies both independently and in synergy with c-Kit. In addition, the activity of this minimal chimera in supporting megakaryocyte development was tested and, remarkably, was observed to approximate that of the endogenous receptor for thrombopoietin. Thus, the box 1 and 2 cytoplasmic subdomains of the Epo receptor, together with a tyrosine 343 site (each retained within EE372), appear to provide all of the signals necessary for the development of committed progenitor cells within both the erythroid and megakaryocytic lineages.     

Apoptosis induced by erythroid differentiation of human leukemia cell lines is inhibited by Bcl-XL

The induction of tumor cell differentiation represents an attractive strategy for the treatment of a wide range of malignancies. Differentiation of HL-60 promyelocytic leukemia cells towards neutrophils or monocytes has been shown to induce apoptotic cell death, which is inhibited by bcl-2 over-expression. However, the role of the bcl-2 gene family during erythroid differentiation of human leukemia cells remains unknown. We found that human erythroleukemia (HEL) and K562, two leukemia cell lines that undergo erythroid differentiation do not express Bcl-2, but express Bcl-XL, a related protein that functions as an inhibitor of apoptosis. Differentiation of HEL or K562 cells with inducers of erythroid differentiation (hemin, retinoic acid, or transforming growth factor-beta) was accompanied by progressive cell death and degradation of genomic DNA into oligonucleosomal fragments. The loss of cellular viability was associated with downregulation of bcl-xL mRNA and protein. In contrast, the levels of Bax, another Bcl-2 family member implicated in apoptosis remained unaltered. Constitutive expression of Bcl-XL by gene transfer inhibited apoptosis triggered by erythroid differentiation of HEL K562 cells. Yet, Bcl-XL did not alter the expression of epsilon-globin, which is induced during erythoid differentiation of HEL and K562 cells, arguing that apoptosis and differentiation can be uncoupled by Bcl-XL. These results indicate that Bcl-XL acts as an antiapoptosis protein in leukemia cells that undergo erythroid differentiation and that downregulation of bcl-x is a component of the apoptotic response that is coupled to differentiation in human leukemia cells.     

Dickkopf1在人脑胶质瘤细胞株中的表达及意义

目的探讨Wnt通路抑制因子Dickkopf-1（DKK1）在人胶质瘤发生、发展中的作用。方法采用ELISA、RT-PCR法检测人胶质瘤细胞株U251和T98G中DKK1蛋白及DKK1 mRNA表达水平。结果DKK1蛋白在U251和T98G中均呈高表达;DKK1mRNA在胶质瘤细胞株U251和T98G中高表达,但在正常脑组织中表达不明显。结论DKK1在人胶质瘤细胞株中高表达;其可能在胶质瘤发生发展中起重要作用。     

Identification of a normal human bone marrow cell population co-expressing megakaryocytic and erythroid markers in culture.

A population of haematopoietic cells co-expressing glycoprotein IIIa (GPIIIa), which has been shown to be present in the megakaryocyte-platelet lineage, and glycophorin A, which has been shown to be specific for the erythroid lineage, has been identified in normal bone marrow cultures using double immunofluorescence staining. The cells showing this phenotype have the size of lymphocytes and appear at an early time (day 1 to d 6) of culture. We have also detected a type of mixed megakaryocyte (MK) cluster containing this phenotype on d 3 or 4 in most normal marrow samples. Such a cell phenotype was not detected after 6 d of culture. It is thus the first time that this phenotype, although already described for several human neoplastic cell lines, has been observed in several normal human bone marrow cultures. Cells expressing this phenotype may represent haematopoietic cells, common to megakaryocytic and erythroid lineages, at a very early stage of differentiation.     

Expression of androgen receptor mRNA in human hepatocellular carcinomas and hepatoma cell lines.

The expression of androgen receptor messenger RNA in hepatocellular carcinomas and hepatoma cell lines was studied using Northern-blot analysis and the complementary DNA-polymerase chain reaction method. Androgen receptor messenger RNAs were detected (although in low levels) in both hepatocellular carcinoma tissues and noncancerous tissues of the liver in all eight cases we studied, except for the tumor sample of one case. None of the hepatoma cell lines studied, however, expressed detectable levels of androgen receptor messenger RNA except for the SK-HEP-1 hepatoma cell line.     

Acquisition of growth autonomy and tumorigenicity by an interleukin 6-dependent human myeloma cell line transfected with interleukin 6 cDNA.

In human multiple myeloma, an autocrine growth mechanism through interleukin 6 (IL-6) has been advocated. However, growth of myeloma cells in vitro is poor except for established cell lines, and IL-6 autocrine growth is quite rare in myeloma cell lines. In the present study, we devised a model of IL-6 autocrine growth in vitro by transfecting IL-6 cDNA into a human myeloma cell line that had a proliferative response to IL-6 but did not produce IL-6. After IL-6 transfection, the cells proliferated in culture media without IL-6, and their growth rate was elevated at higher cell densities. IL-6 was detected by enzyme-linked immunosorbent assay in the culture media of the transfectants. IL-6 mRNA was distinctly expressed in these cells when analyzed by Northern blotting. The growth of the transfectants was definitely inhibited by anti-IL-6 or anti-IL-6 receptor monoclonal antibodies. Furthermore, the transfectants were successfully transplanted to nude mice. These results indicate that the myeloma cells obtained growth autonomy in vitro through IL-6 and tumorigenicity in vivo, after IL-6 transfection.     

A novel strategy for generating platelet-like fragments from megakaryocytic cell lines and human progenitor cells

Transfusion of allogeneic platelets is the mainstay of therapy for patients with thrombocytopenic hemorrhage. However, donated platelets can only be stored for 5 days and are maintained at room temperature, increasing the risk of bacterial growth. Developing a method to produce functional platelets in vitro would greatly advance transfusion therapy. During our studies to understand megakaryocyte development, we discovered that a Src kinase inhibitor, SU6656, induces cellular enlargement, polyploidization, and cytoplasmic fragmentation of several hematopoietic cell lines. Therefore, we tested the hypothesis that these fragments possess platelet-like activity. We studied a megakaryocytic cell-line, UT-7/TPO, and immature human primary megakaryocytes. After 6 days in the presence of thrombopoietin and SU6656, the majority of cells became polyploid and started shedding platelet-like fragments. These fragments were tested for aggregation and analyzed by electron microscopy. The platelet-like fragments did not undergo spontaneous activation but did show rapid and sustained aggregation in response to each of the standard agonists collagen, arachidonic acid, adenosine diphosphate, and epinephrine. Platelet-like fragments generated in SU6656 had higher amplitude and more prolonged aggregation in each of three experiments. Primary progenitors developed demarcation membranes within 72 h and evidence of dense granules and platelet-like fragments after 6 days. These cell fragments demonstrated properties consistent with platelet aggregation in response to multiple agonists without spontaneous aggregation. These studies provide evidence that SU6656 promotes megakaryocytic differentiation and thrombopoiesis in vitro.     

Expression cloning of the murine and human interleukin 9 receptor cDNAs.

Interleukin 9 (IL-9) is a T-cell-derived lymphokine that induces the proliferation of various lymphoid and hemopoietic cells. A cDNA clone encoding the murine IL-9 receptor was isolated by expression cloning in COS cells and screening with 125I-labeled IL-9. Transient expression of this cDNA produced high-affinity binding sites for IL-9. The predicted 52-kDa protein contains a putative signal peptide and a typical transmembrane domain. A cDNA for the human homologue was isolated by cross-hybridization. Transfection of this cDNA in a murine T-cell clone conferred responsiveness to human IL-9. Sequence analysis revealed that the IL-9 receptor belongs to the recently described hematopoietin receptor super-family and is expressed in membrane-bound and soluble forms.     

胰腺癌细胞系血管紧张素Ⅱ 1型受体蛋白表达的研究

目的探讨血管紧张素Ⅱ 1型受体(angiotensin Ⅱ type 1 receptor,AT1)在胰腺癌细胞中的表达.方法用免疫细胞化学染色检测胰腺癌细胞系SW1990、PaTu 8988s和PANC-1中AT1蛋白的表达.结果胰腺癌细胞系SW1990、PaTu 8988s和PANC-1中均有AT1蛋白的表达.结论 AT1在胰腺癌细胞生长中可能发挥重要作用,应用AT1拮抗剂对防治胰腺癌似乎有一定意义.     

Regulation of interleukin 1 and its receptor in human keratinocytes.

Keratinocytes in culture synthesize and respond to interleukin 1 (IL-1). We have measured surface IL-1 receptor (IL-1R) on keratinocytes in culture using radiolabeled IL-1 binding assays. Surface IL-1R levels are less than 2000 receptors per cell in postconfluent cultures but increase 9- to 20-fold 24 hr after treatment with phorbol 12-myristate 13-acetate (PMA) at 10 ng/ml or after raising the extracellular Ca2+ concentration to 2 mM. This induction of surface IL-1R can be blocked by the addition of retinoic acid and parallels induction of squamous differentiation markers. These results imply that IL-1R levels may be related to the degree of differentiation of these cells. In parallel studies IL-1 protein levels were determined by bioassay and by Western blotting (immunoblots). All detectable IL-1 protein and essentially all IL-1 activity was cell-associated. Although constitutive levels of IL-1 biological activity and protein are significant in these cultures, IL-1 levels increase when either PMA or retinoic acid alone are added to cultures. IL-1 does not increase when PMA and retinoic acid are added simultaneously to cultures; nor is it induced when extracellular Ca2+ concentrations are raised to 2 mM. Thus, cell-associated IL-1 levels do not necessarily parallel surface IL-1R levels in these cultures. Taken together, these results demonstrate that IL-1 and surface IL-1R levels are differentially and complexly regulated in keratinocyte cultures. Possible implications of these results in terms of normal and abnormal regulation of proliferation and differentiation are discussed.