Telomerase activity and in situ telomerase RNA expression in malignant and non-malignant lymph nodes.

AIMS/BACKGROUND: Telomerase, an enzyme associated with cellular immortality, is expressed by most malignant tumours, but is inactive in normal somatic cells except for male germ cells and proliferating stem cells. Thus, the measurement of telomerase activity in tissue samples may provide useful diagnostic and prognostic information. The aim of this study was to determine whether telomerase expression is useful for the detection of occult malignant cells in lymph nodes. METHODS: Telomerase activity was compared with histological findings in 123 surgically removed lymph nodes submitted for routine or frozen section diagnosis. Telomerase activity was measured using a modified, semi-quantitative PCR-based telomeric repeat amplification protocol (TRAP). The assay was adapted for single 5 microns OCT embedded cryostat sections. In either fresh tissues or cryostat sections, normalised activity was linear when compared with protein concentration. Furthermore, using an in situ hybridisation method, the human telomerase RNA (hTR) component was measured in a subset of negative and positive nodes. RESULTS: Most (96%) of the 97 histologically negative nodes expressed low levels of activity (mean value of positive samples = 3.0 units/microgram protein) which may be derived from activated lymphocytes that express telomerase activity. All 26 malignant nodes (17 metastases, nine lymphomas) expressed telomerase (mean value = 17.8 units/microgram protein). The rank order levels between the two groups differed significantly (p = 0.0002). In situ results showed clearly that the hTR was expressed relatively highly in metastatic cancer cells and at lower levels in germinal centres of secondary follicles. CONCLUSIONS: Although expression of telomerase by activated lymphocytes may limit its usefulness, measurement of enzyme activity combined with detection of hTR using in situ hybridisation may assist in the histopathological diagnosis of lymph nodes.     

Genetic control of expression of endogenous virus genes in chicken cells

Some chicken embryos which are known to be free of virus, nevertheless contain viral products, the group specific (gs) antigen and the virus envelope proteins, which are specific to avian leukosis-sarcoma viruses. The envelope proteins seem to confer these cells with the helper activity for defective sarcoma virus. The formation of these products appears to be determined by a single pair of autosomal genes. The presence of the products is dominant over the absence. Thus, by characterizing the genotype of each individual chicken, it was possible to breed a flock of chickens that are negative for the viral expression. With over 95% of the embryos, two virus-specific properties, the formation of gs antigen and helper activity, were either expressed or unexpressed concurrently. However, some embryos display unusually high levels of helper activity with low or undetectable amounts of gs antigen. In this type of embryo, the formation of particularly high titers of virus was observed only for the virus which is formed by the assistance of the endogenous helper factor. Evidence suggests that this property is also genetically controlled.     

Rearrangements of c-myc and c-abl genes in tumour cells in Burkitt's lymphoma.

Rearrangements of oncogenes c-myc and c-abl were detected by non-radioactive hybridisation in a case of Burkitt's lymphoma/leukaemia. The surface phenotype of Burkitt's cells were positive for CD19, CD20, HLA-DR, CD14, CD33 and surface immunoglobulin markers. Although cytogenetic analysis was not performed, the c-myc and heavy immunoglobulin genes had the same 14.2 kilobase EcoRI molecular size fragment, suggesting a possible t(8;14) translocation which is a common marker of this malignancy. The c-abl oncogene was also rearranged in DNA digested BamHI and EcoRI. The physiopathological implications of the rearranged c-abl gene are unknown, this being the first case, as for as is known, of Burkitt's lymphoma/leukaemia with a rearranged c-abl gene.     

Lack of correlation between telomere length and telomerase activity and expression in leukemic cells

The expression of three components of telomerase complex (hTR, hTERT, TP1) along with telomerase activity and telomere length in leukemic cells was investigated. Cells were isolated from peripheral blood and/or bone marrow of children with acute lymphoblastic (ALL) and non-lymphoblastic (ANLL) leukemia. Expression of three components of telomerase as well as telomerase activity was found in all leukemic cells. Chemiluminescent detection of terminal restriction fragments (TRF) from DNA isolated from ALL cells showed variable patterns expressing considerable heterogeneity of telomere length. The ALL cells appeared to have both long and short telomere lengths, in contrast to normal peripheral lymphocytes, which produced limited pattern of TRF. The ANLL cells produced predominantly short telomere pattern despite high telomerase activity and expression. It can be concluded that high telomerase activity and expression in leukemic cells is not always correlated with long telomeres (TRF pattern).     

端粒酶活性在骨髓间充质干细胞体外分化过程中的表达观察

为了探讨兔骨髓间充质干细胞体外增殖前后及诱导分化内皮细胞过程中端粒酶活性的表达及意义，我们联合应用密度梯度离心和贴壁培养法分离骨髓间充质干细胞，继而诱导其向内皮细胞方向分化，用TRAPeze ELISA法分别检测新鲜分离的骨髓细胞及骨髓间充质干细胞、原代培养的内皮样细胞及传代细胞端粒酶活性，结果发现新鲜分离的骨髓细胞及增殖前的骨髓间充质干细胞端粒酶活性低水平表达，一旦经过VEGF诱导分化，细胞端粒酶活性表达上调，在5代内其端粒酶活性不因细胞传代而下降或消失，说明骨髓间充质干细胞体外有限扩增和诱导分化时保持端粒酶活性，维持组织干细胞特性，为组织干细胞的临床研究奠定理论基础。     

胶质瘤细胞c—fos和c—myc基因表达与血小板源生长因子B链的？…

目的 探讨胶质瘤细胞ｃ－ｆｏｓ和ｃ－ｍｙｃ基因表达和血小板源生长因子Ｂ链的纯合二聚体自分泌环活性的改变及其相互关系。方法 用原位杂交和免疫组化方法观察了６７例人胶质瘤组织。结果 ６７例中,ｃ－ｆｏｓ ｍＲＮＡ,ｃ－ｆｏｓ蛋白,ｃ－ｍｙｃ ｍＲＮＡ及ｃ－ｍｙｃ蛋白阳性率分别为;１００％,１００％,８５．１％,８３．６％。     

丙型肝炎病毒核心蛋白在HepG2细胞中的表达及其对端粒酶活性的影响

目的 建立HCV核心蛋白细胞表达模型，并探讨其对细胞端粒酶活性的影响。方法 用PCR法扩增出HCV核心基因cDNA，将其插入真核表达载体pBK-CMV的HindⅢ和BamHⅠ位点间，构建重组质粒pBK-HCVc。再将重组质粒pBK-HCVc和空载体分别导入肝癌细胞株HepG2中，G418筛选，RT－PCR、免疫组化和蛋白印迹鉴定HCV核心蛋白表达。PCR－ELISA法检测端粒酶活性。结果 构建的pBK-HCVc质粒在HepG2细胞中有稳定表达。表达HCV核心蛋白的细胞HepG2-C的端粒酶活性较转染空载体的细胞HepG2-CMV明显升高。结论 HCV核心蛋白上调了端粒酶活性，可能是HCV诱发肝细胞癌的一种途径。     

AML患者端粒酶逆转录酶mRNA的表达与端粒酶活性的检测

目的:建立一种实时荧光RT-PCR方法,定量检测急性髓细胞白血病(AML)患者外周血单个核细胞端粒酶逆转录酶(hTERT)mRNA的表达水平,观察其与AML发生及复发的关系,探讨hTERT mRNA的表达水平与端粒酶活性的相关关系。方法:采用实时荧光RT-PCR与Lightcycler荧光PCR仪定量检测hTERT mRNA的表达水平,采用PCR-ELISA检测端粒酶活性。结果:①AML首治患者、复发患者、完全缓解期患者以及健康体检者NhTERT分别为299.2±292.8、550.1±441.3、14.0±9.2和12.3±6.7,与健康体检者和完全缓解期患者比较,AML首治患者、复发患者hTERT mRNA表达水平显著升高,而且AML复发患者hTERT mRNA的表达水平显著高于首治患者;②AML首治患者、AML复发患者、AML完全缓解期患者以及健康体检者端粒酶的活性分别为32.8%±24.3%4、8.6%±31.4%、7.4%±5.1%和7.6%±3.6%,AML首治患者、复发患者端粒酶活性显著升高,而且AML复发患者端粒酶活性显著高于首治患者;③hTERT mRNA表达水平与端粒酶的活性呈现良好的相关性,相关系数为0.78。结论:hTERT mRNA表达水平与端粒酶活性的上调是AML发生与复发的一个重要因素,且hTERT mRNA表达水平与端粒酶活性呈良好的正相关。     

三氧化二砷对K562细胞端粒酶活性及P53蛋白表达水平的调节

目的：研究三氧化二砷(As2O3)诱导急性白血病K562细胞的凋亡机制。方法：以不同浓度的As2O3作用于体外培养的K562细胞，检测细胞生长抑制率，观察细胞凋亡时的形态学变化，对细胞端粒酶活性及P53蛋白的表达水平进行检测。结果：As2O3可显著地降低K562细胞端粒酶活性，升高P53蛋白的表达水平，抑制细胞的生长，诱导细胞发生凋亡。并呈现出明显的量-效与时-效关系。结论：As2O3能抑制K562细胞的生长并诱导细胞发生凋亡，降低细胞端粒酶活性及升高P53蛋白的表达水平是其重要作用机制之一。     

蛋白激酶C的活性变化对人肝癌细胞增殖及端粒酶表达的影响

目的:揭示蛋白激酶C(PKC)活性变化对人肝癌细胞增殖及端粒酶表达的影响。方法: 体外以PKC激活剂PMA(phorbol-12-myristate-13-acetate)及其抑制剂星形孢菌素(staurosporine,SP)作用于人肝癌细胞系(BEL-7402)48 h后,运用TRAP-银染(telomeric repeat amplification protocol silver staining)与计算机图像凝胶扫描记录技术结合的方法来揭示细胞端粒酶活性、PKC变化与细胞增殖的关系。结果:PMA与SP的作用,促进其细胞增殖抑制的同时,抑制其细胞端粒酶活性表达。结论:PKC的活性变化与人肝癌细胞增殖相关,并可能与端粒酶的活性表达关联。     

T-cell receptor variable beta genes show differential expression in CD4 and CD8 T cells.

Studies in transgenic and inbred strains of mice have shown that the critical molecular interactions controlling positive selection involve major histocompatibility complex (MHC), T-cell receptor (TCR), and CD4 or CD8 coreceptor molecules. Correlations have been established between MHC gene products and the percentage of CD4 or CD8 T cells that express specific variable (V) beta-gene products as part of the alpha beta heterodimer. These studies have important implications regarding potential mechanisms of HLA-linked autoimmune diseases in humans. If similar interactions are required for positive selection in humans, one would predict that the TCR repertoire expressed by mature, peripheral blood CD4 and CD8 T cells would vary. To test this hypothesis the expression of specific TCR V beta-region genes by CD4 and CD8 T cells from healthy individuals was compared using both triple-color flow cytometry and polymerase chain reaction based experimental approaches. The results show that the TCR repertoire does vary as a function of CD4 and CD8 T-cell subsets. Among unrelated individuals certain V beta genes were consistently overrepresented in the CD4 population (V beta-5.1, -6.7a, and -18); some were skewed to the CD8 population (V beta-14) while others showed variable patterns (V beta-12 and -17). Deletion of entire V beta gene families was not observed suggesting that this is a rare event in humans. Attempts to correlate the expressed TCR repertoire in humans with HLA alleles will require consideration of these differences in expression as a function of subset.     

Antigenic surface determinants of chicken lymphoid cells. II. Selective in vivo and in vitro activity of anti-bursa and anti-thymus sera.

Appropriately absorbed turkey antisera to antigenic surface determinants of chicken bursa (ABS) or thymus cells (ATS) were assessed for their selective immunosuppressive activy in vitro and in vivo. The intraperitoneal injection of ABS or ATS into 2-3-week-old normal white Leghorn chickens entailed a significant depletion of B or T cells respectively from spleen and peripheral blood, while bursa and thymus themselves remained unaffected. The potential of this 'peripheral serological bursectomy and thymectomy' paralleled that found after the conventional surgical procedures with subsequent sublethal irradiation. The mean survival time of skin allografts from donors of genotype B4B4 onto B8B8 recipients was significantly prolonged by treatment with ATS (29 plus or minus 12 days) as compared to untreated (14 plus or minus 2 days), normal turkey serum (12 plus or minus 3 days) or ABS-injected (13 plus or minus 2 days) groups. This selective suppression of a T cell-dependent immune reaction by ATS was also confirmed in vitro by its inhibitory action on the graft-versus-host reactivity of adult peripheral blood lymphocytes in the chorioallantoic membrane assay, where normal turkey serum and ABS were again ineffective. Thus, ABS or ATS produced in avian species may serve not only to delineate B and T cells in vitro, but can also be used for selective manipulation of immune reactions of the chicken in vivo.     

脂肪组织源性肿瘤中c-myc和p53基因的异常表达

目的：探讨脂肪组织源性肿瘤与ｃ－ｍｙｃ和ｐ５３基因的关系。方法：采用ＬＳＡＢ免疫组化法,检测６２例脂肪组织源性肿瘤及瘤样病变ｃ－ｍｙｃ和ｐ５３蛋白表达。结果ｃ－ｍｙｃ在正常脂肪组织、脂肪组织良性病变中几乎不表达,主要在脂肪肉瘤中表达。ｐ５３只在脂肪肉瘤中表达。分化较高类型脂肪肉瘤ｃ－ｍｙｃ和ｐ５３表达阳性率明显低于分化较低类型脂肪肉瘤,脂肪肉瘤中,ｃ－ｍｙｃ和ｐ５３表达呈正相关。结论：实验结果提示     

姜黄素抑制HeLa细胞端粒酶的活性

目的研究姜黄素能否抑制HeLa细胞端粒酶活性。方法用MTT法检测姜黄素对HeLa细胞生长的抑制作用,用RT-PCR和半定量TRAP-ELISA法检测HeLa细胞中人端粒酶催化亚基(hTERT)mRNA的表达和端粒酶活性。结果HeLa细胞生长呈剂量依赖性抑制,其端粒酶活性和hTERT的表达也明显下调。结论姜黄素可能通过下调hTERT的表达而抑制HeLa细胞的端粒酶活性。     

卵巢癌组织中Bmi-1蛋白的表达与端粒酶活性的关系

目的通过检测癌基因Bmi-1在卵巢上皮癌中表达情况,探讨其与端粒酶活性的关系。方法①使用Reahime—PCR的方法检测47例卵巢上皮癌组织中Bmi-1基因的mRNA表达情况;②采用免疫组化SP法检测47例卵巢上皮癌组织中Bmi-1蛋白的表达;③改良端粒重复序列扩增技术（telomerase repeat amplification protocol）——TRAP-银染技术检测该47例卵巢上皮癌组织中端粒酶基因水平;④Western Blot检测卵巢上皮癌组织中端粒酶蛋白表达量。结果①Bmi-1蛋白在卵巢上皮癌组织中较正常组织有明显表达（P〈0．05）,并且与病理分级和临床分期有关,G3级阳性表达率（93．10％）高于G2级（61．11％）,Ⅱ期、Ⅲ期阳性表达率（66．67％）低于Ⅳ期（92．31％）,二者均有统计学差异（P〈0．05）。②卵巢上皮癌组织中端粒酶活性阳性检测率为87．23％（41／47）,正常组织中阴性表达;③端粒酶活性阳性标本中Bmi-1蛋白高表达,占90．24％,spearman相关性分析显示Bmi-1蛋白表达与端粒酶活性阳性率呈正相关（P〈0．05）。结论Bmi-1基因和蛋白在卵巢上皮癌组织中高表达,其表达率与组织学分级和临床期别相关;Bmi-1阳性率与端粒酶活性阳性率密切相关,其在卵巢癌的发病过程中可能有重要意义．值得进一步研究。