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Sample records for beta-mediated human telomerase

  1. Human telomerase contains two cooperating telomerase RNA molecules

    OpenAIRE

    Wenz, Christian; Enenkel, Barbara; Amacker, Mario; Kelleher, Colleen; Damm, Klaus; Lingner, Joachim

    2001-01-01

    Telomerase uses a short stretch of its intrinsic RNA molecule as template for telomere repeat synthesis. Reverse transcription of the RNA template is catalyzed by the telomerase reverse transcriptase (TERT) protein subunit. We demonstrate that human telomerase reconstituted from recombinant TERT and telomerase RNA runs as a dimer on a gel filtration column and that it contains two telomerase RNA molecules. Significantly, a telomerase heterodimer reconstituted from wild-type and mutant telomer...

  2. Human telomerase activity regulation

    OpenAIRE

    Wojtyla, Aneta; Gladych, Marta; Rubis, Blazej

    2010-01-01

    Telomerase has been recognized as a relevant factor distinguishing cancer cells from normal cells. Thus, it has become a very promising target for anticancer therapy. The cell proliferative potential can be limited by replication end problem, due to telomeres shortening, which is overcome in cancer cells by telomerase activity or by alternative telomeres lengthening (ALT) mechanism. However, this multisubunit enzymatic complex can be regulated at various levels, including expression control b...

  3. TELOMERASE AND CHRONIC ARSENIC EXPOSURE IN HUMANS

    Science.gov (United States)

    Arsenic exposure has been associated with increased risk of skin, lung and bladder cancer in humans. The mechanisms of carcinogenesis are not well understood. Telomerase, a ribonucleoprotein containing human telomerase reverse transcriptase (hTERT), can extend telomeres of eukary...

  4. Polymerization Defects within Human Telomerase Are Distinct from Telomerase RNA and TEP1 Binding

    OpenAIRE

    Beattie, Tara L.; Zhou, Wen; Robinson, Murray O; Harrington, Lea

    2000-01-01

    The minimal, active core of human telomerase is postulated to contain two components, the telomerase RNA hTER and the telomerase reverse transcriptase hTERT. The reconstitution of human telomerase activity in vitro has facilitated the identification of sequences within the telomerase RNA and the RT motifs of hTERT that are essential for telomerase activity. However, the precise role of residues outside the RT domain of hTERT is unknown. Here we have delineated several ...

  5. Telomerase activity in human cancer

    Energy Technology Data Exchange (ETDEWEB)

    Griffith, J.

    2000-10-01

    The overall goal of this collaborative project was to investigate the role in malignant cells of both chromosome telomeres, and telomerase, the enzyme that replicates telomeres. Telomeres are highly conserved nucleoprotein complexes located at the ends of eucaryotic chromosomes. Telomere length in somatic cells is reduced by 40--50 nucleotide pairs with every cell division due to incomplete replication of terminal DNA sequences and the absence of telomerase, the ribonucleoprotein that adds telomere DNA to chromosome ends. Although telomerase is active in cells with extended proliferative capacities, including more than 85% of tumors, work performed under this contract demonstrated that the telomeres of human cancer cells are shorter than those of paired normal cells, and that the length of the telomeres is characteristic of particular types of cancers. The extent of telomere shortening ostensibly is related to the number of cell divisions the tumor has undergone. It is believed that ongoing cell proliferation leads to the accumulation and fixation of new mutations in tumor cell lineages.Therefore, it is not unreasonable to assume that the degree of phenotypic variability is related to the proliferative history of the tumor, and therefore to telomere length, implying a correlation with prognosis. In some human tumors, short telomeres are also correlated with genomic instabilities, including interstitial chromosome translocation, loss of heterozygosity, and aneuoploidy. Moreover, unprotected chromosome ends are highly recombinogenic and telomere shortening in cultured human cells correlates with the formation of dicentric chromosomes, suggesting that critically short telomeres not only identify, but also predispose, cells to genomic instability, again implying a correlation with prognosis. Therefore, telomere length or content could be an important predictor of metastatic potential or responsiveness to various therapeutic modalities.

  6. Protein composition of catalytically active human telomerase from immortal cells

    DEFF Research Database (Denmark)

    Cohen, Scott B; Graham, Mark E; Lovrecz, George O;

    2007-01-01

    Telomerase is a ribonucleoprotein enzyme complex that adds 5'-TTAGGG-3' repeats onto the ends of human chromosomes, providing a telomere maintenance mechanism for approximately 90% of human cancers. We have purified human telomerase approximately 10(8)-fold, with the final elution dependent on the...... enzyme's ability to catalyze nucleotide addition onto a DNA oligonucleotide of telomeric sequence, thereby providing specificity for catalytically active telomerase. Mass spectrometric sequencing of the protein components and molecular size determination indicated an enzyme composition of two molecules...... each of telomerase reverse transcriptase, telomerase RNA, and dyskerin....

  7. An Alternate Splicing Variant of the Human Telomerase Catalytic Subunit Inhibits Telomerase Activity

    Directory of Open Access Journals (Sweden)

    Xiaoming Yi

    2000-09-01

    Full Text Available Telomerase, a cellular reverse transcriptase, adds telomeric repeats to chromosome ends. In normal human somatic cells, telomerase is repressed and telomeres progressively shorten, leading to proliferative senescence. Introduction of the telomerase (hTERT cDNA is sufficient to produce telomerase activity and immortalize normal human cells, suggesting that the repression of telomerase activity is transcriptional. The telomerase transcript has been shown to have at least six alternate splicing sites (four insertion sites and two deletion sites, and variants containing both or either of the deletion sites are present during development and in a panel of cancer cell lines we surveyed. One deletion (β site and all four insertions cause premature translation terminations, whereas the other deletion (α site is 36 by and lies within reverse transcriptase (RT motif A, suggesting that this deletion variant may be a candidate as a dominant-negative inhibitor of telomerase. We have cloned three alternately spliced hTERT variants that contain the α,β or both α and,β deletion sites. These alternate splicing variants along with empty vector and wild-type hTERT were introduced into normal human fibroblasts and several telomerase-positive immortal and tumor cell lines. Expression of the α site deletion variant (hTERT α− construct was confirmed by Western blotting. We found that none of the three alternate splicing variants reconstitutes telomerase activity in fibroblasts. However, hTERT α− inhibits telomerase activities in telomerase-positive cells, causes telomere shortening and eventually cell death. This alternately spliced dominant-negative variant may be important in understanding telomerase regulation during development, differentiation and in cancer progression.

  8. Telomerase activity and human telomerase reverse transcriptase expression in colorectal carcinoma

    OpenAIRE

    Liu, Jian-Lun; GE, LIAN-YING; Zhang, Gui-Nian

    2006-01-01

    AIM: To study the activity of telomerase and the expression of human telomerase reverse transcriptase (hTERT) in colorectal carcinoma and its adjacent tissues, normal mucosa and adenomatoid polyp, and to evaluate their relation with carcinogenesis and progression of colorectal carcinoma.

  9. Telomere elongation in immortal human cells without detectable telomerase activity.

    OpenAIRE

    Bryan, T M; Englezou, A; J Gupta; Bacchetti, S; Reddel, R. R.

    1995-01-01

    Immortalization of human cells is often associated with reactivation of telomerase, a ribonucleoprotein enzyme that adds TTAGGG repeats onto telomeres and compensates for their shortening. We examined whether telomerase activation is necessary for immortalization. All normal human fibroblasts tested were negative for telomerase activity. Thirteen out of 13 DNA tumor virus-transformed cell cultures were also negative in the pre-crisis (i.e. non-immortalized) stage. Of 35 immortalized cell line...

  10. Telomerase activity and human telomerase reverse transcriptase expression in colorectal carcinoma

    Institute of Scientific and Technical Information of China (English)

    Jian-Lun Liu; Lian-Ying Ge; Gui-Nian Zhang

    2006-01-01

    AIM: To study the activity of telomerase and the expression of human telomerase reverse transcriptase(hTERT) in colorectal carcinoma and its adjacent tissues,normal mucosa and adenomatoid polyp, and to evaluate their relation with carcinogenesis and progression of colorectal carcinoma.METHODS: Telomerase activity and hTERT expression were determined in 30 samples of colorectal carcinoma and its adjacent tissues, normal mucosa and 20samples of adenomatoid polyp by modified telomeric repeat amplification protocol (TRAP), enzyme-linked immunosorbent assay (ELISA) and immunohistochemical method.RESULTS: Telomerase activity and hTERT expression were 83.33% (25/30) and 76.67% (23/30) respectively in colorectal carcinoma, which were obviously higher than those in paracancerous tissues (13.33%, 16.67%),normal mucosa (3.33%, 3.33%) and adenomatoid polyp(10%, 10%). There was a significant difference between colorectal carcinoma and other tissues (P=0.027). The telomerase activity and hTERT expression were higher in colorectal carcinoma with lymphatic metastasis than in that without lymphatic metastasis (P=0.034). When the histological classification and clinical stage were greater,the telomerase activity and hTERT expression increased,but there was no significant difference between them.In colorectal carcinoma, the telomerase activity was correlated with hTERT expression (positive vs negative expression of telomerase activity and hTERT, P=0.021).CONCLUSION: Telomerase activity is closely correlated with the occurrence, development and metastasis of colorectal carcinoma. Overexpression of hTERT may play a critical role in the regulation of telomerase activity.

  11. Coordinated DNA dynamics during the human telomerase catalytic cycle

    OpenAIRE

    Joseph W. Parks; Stone, Michael D.

    2014-01-01

    The human telomerase reverse transcriptase (hTERT) utilizes a template within the integral RNA subunit (hTR) to direct extension of telomeres. Telomerase exhibits repeat addition processivity (RAP) and must therefore translocate the nascent DNA product into a new RNA:DNA hybrid register to prime each round of telomere repeat synthesis. Here we use single-molecule FRET and nuclease protection assays to monitor telomere DNA structure and dynamics during the telomerase catalytic cycle. DNA trans...

  12. Identification of Two RNA-binding Proteins Associated with Human Telomerase RNA

    OpenAIRE

    Le, Siyuan; Sternglanz, Rolf; Greider, Carol W

    2000-01-01

    Telomerase plays a crucial role in telomere maintenance in vivo. To understand telomerase regulation, we have been characterizing components of the enzyme. To date several components of the mammalian telomerase holoenzyme have been identified: the essential RNA component (human telomerase RNA [hTR]), the catalytic subunit human telomerase reverse transcriptase (hTERT), and telomerase-associated protein 1. Here we describe the identification of two new proteins that interact with hTR: hStau an...

  13. A human telomerase holoenzyme protein required for Cajal body localization and telomere synthesis

    OpenAIRE

    Venteicher, Andrew S.; Abreu, Eladio B.; Meng, Zhaojing; McCann, Kelly E.; Terns, Rebecca M.; Veenstra, Timothy D.; Terns, Michael P.; Artandi, Steven E.

    2009-01-01

    Telomerase is a ribonucleoprotein (RNP) complex that synthesizes telomere repeats in tissue progenitor cells and cancer cells. Active human telomerase consists of at least three principal subunits, including the telomerase reverse transcriptase (TERT), the telomerase RNA (TERC), and dyskerin. Here, we identify a holoenzyme subunit, TCAB1 (telomerase Cajal body protein1), uniquely enriched in Cajal bodies, nuclear sites of RNP processing important for telomerase function. TCAB1 associates with...

  14. Telomerase Regulation

    OpenAIRE

    Cifuentes-Rojas, Catherine; Dorothy E Shippen

    2011-01-01

    The intimate connection between telomerase regulation and human disease is now well established. The molecular basis for telomerase regulation is highly complex and entails multiple layers of control. While the major target of enzyme regulation is the catalytic subunit TERT, the RNA subunit of telomerase is also implicated in telomerase control. In addition, alterations in gene dosage and alternative isoforms of core telomerase components have been described. Finally, telomerase localization,...

  15. Actions of human telomerase beyond telomeres

    Institute of Scientific and Technical Information of China (English)

    Yusheng Cong; Jerry W Shay

    2008-01-01

    Telomerase has fundamental roles in bypassing cellular aging and in cancer progression by maintaining telomere homeostasis and integrity. However, recent studies have led some investigators to suggest novel biochemical properties of telomerase in several essential cell signaling pathways without apparent involvement of its well established function in telomere maintenance. These observations may further enhance our understanding of the molecular actions of telomerase in aging and cancer. This review will provide an update on the extracurricular activities of telomerase in apoptosis, DNA repair, stem cell function, and in the regulation of gene expression.

  16. Telomere Transcripts Target Telomerase in Human Cancer Cells.

    Science.gov (United States)

    Kreilmeier, Theresa; Mejri, Doris; Hauck, Marlene; Kleiter, Miriam; Holzmann, Klaus

    2016-01-01

    Long non-coding transcripts from telomeres, called telomeric repeat-containing RNA (TERRA), were identified as blocking telomerase activity (TA), a telomere maintenance mechanism (TMM), in tumors. We expressed recombinant TERRA transcripts in tumor cell lines with TA and with alternative lengthening of telomeres (ALT) to study effects on TMM and cell growth. Adeno- and lentivirus constructs (AV and LV) were established for transient and stable expression of approximately 130 units of telomere hexanucleotide repeats under control of cytomegalovirus (CMV) and human RNase P RNA H1 (hH1) promoters with and without polyadenylation, respectively. Six human tumor cell lines either using telomerase or ALT were infected and analyzed for TA levels. Pre-infection cells using telomerase had 1%-3% of the TERRA expression levels of ALT cells. AV and LV expression of recombinant TERRA in telomerase positive cells showed a 1.3-2.6 fold increase in TERRA levels, and a decrease in TA of 25%-58%. Dominant-negative or small hairpin RNA (shRNA) viral expression against human telomerase reverse transcriptase (hTERT) results in senescence, not induced by TERRA expression. Population doubling time, cell viability and TL (telomere length) were not impacted by ectopic TERRA expression. Clonal growth was reduced by TERRA expression in TA but not ALT cell lines. ALT cells were not affected by treatments applied. Established cell models and tools may be used to better understand the role of TERRA in the cell, especially for targeting telomerase. PMID:27537914

  17. Telomerase Activity in Human Ovarian Carcinoma

    Science.gov (United States)

    Counter, Christopher M.; Hirte, Hal W.; Bacchetti, Silvia; Harley, Calvin B.

    1994-04-01

    Telomeres fulfill the dual function of protecting eukaryotic chromosomes from illegitimate recombination and degradation and may aid in chromosome attachment to the nuclear membrane. We have previously shown that telomerase, the enzyme which synthesizes telomeric DNA, is not detected in normal somatic cells and that telomeres shorten with replicative age. In cells immortalized in vitro, activation of telomerase apparently stabilizes telomere length, preventing a critical destabilization of chromosomes, and cell proliferation continues even when telomeres are short. In vivo, telomeres of most tumors are shorter than telomeres of control tissues, suggesting an analogous role for the enzyme. To assess the relevance of telomerase and telomere stability in the development and progression of tumors, we have measured enzyme activity and telomere length in metastatic cells of epithelial ovarian carcinoma. We report that extremely short telomeres are maintained in these cells and that tumor cells, but not isogenic nonmalignant cells, express telomerase. Our findings suggest that progression of malignancy is ultimately dependent upon activation of telomerase and that telomerase inhibitors may be effective antitumor drugs.

  18. Coordinated DNA dynamics during the human telomerase catalytic cycle

    Science.gov (United States)

    Parks, Joseph W.; Stone, Michael D.

    2014-06-01

    The human telomerase reverse transcriptase (hTERT) utilizes a template within the integral RNA subunit (hTR) to direct extension of telomeres. Telomerase exhibits repeat addition processivity (RAP) and must therefore translocate the nascent DNA product into a new RNA:DNA hybrid register to prime each round of telomere repeat synthesis. Here, we use single-molecule FRET and nuclease protection assays to monitor telomere DNA structure and dynamics during the telomerase catalytic cycle. DNA translocation during RAP proceeds through a previously uncharacterized kinetic substep during which the 3‧-end of the DNA substrate base pairs downstream within the hTR template. The rate constant for DNA primer realignment reveals this step is not rate limiting for RAP, suggesting a second slow conformational change repositions the RNA:DNA hybrid into the telomerase active site and drives the extrusion of the 5‧-end of the DNA primer out of the enzyme complex.

  19. Inventory of telomerase components in human cells reveals multiple subpopulations of hTR and hTERT

    OpenAIRE

    Xi, Linghe; Cech, Thomas R.

    2014-01-01

    Telomerase is the ribonucleoprotein (RNP) enzyme that elongates telomeric DNA to compensate for the attrition occurring during each cycle of DNA replication. Knowing the levels of telomerase in continuously dividing cells is important for understanding how much telomerase is required for cell immortality. In this study, we measured the endogenous levels of the human telomerase RNP and its two key components, human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT). We est...

  20. Effect of antisense oligodeoxynucleotide of telomerase RNA on telomerase activity and cell apoptosis in human colon cancer

    Institute of Scientific and Technical Information of China (English)

    Ying-An Jiang; He-Sheng Luo; Li-Fang Fan; Chong-Qing Jiang; Wei-Jin Chen

    2004-01-01

    AIM: To explore the effect of antisense oligodeoxynucleotide (As-ODN) of telomerase RNA on telomerase activity and cell apoptosis in human colon cancer.METHODS: As-ODN waS transfected into SW480 cells by liposomal transfection reagent. Telomerase activity of SW480 cells was examined by telomeric repeat amplification protocol (TRAP) and enzyme-linked immunosorbent assay (ELISA).Apoptosis was analyzed by morphology and flow cytometry.RESULTS: The telomerase activity in SW480 cells trandected with 1.0 μmol/L of As-ODN for 2-5 days, was significantly decreased in a time-dependent manner, and the cells underwent apoptosis. The missense ODN (Ms-ODN) and the control group transfected with SW480 cells did not show these changes.CONCLUSION: As-ODN can specifically inhibit the telomerase activity of SW480 cells and induce apoptosis.

  1. A low threshold level of expression of mutant-template telomerase RNA inhibits human tumor cell proliferation

    OpenAIRE

    Kim, Moses M.; Rivera, Melissa A.; Botchkina, Inna L.; Shalaby, Refaat; Thor, Ann D; Elizabeth H. Blackburn

    2001-01-01

    The ribonucleoprotein telomerase synthesizes telomeric DNA by copying an intrinsic RNA template. In most cancer cells, telomerase is highly activated. Here we report a telomerase-based antitumor strategy: expression of mutant-template telomerase RNAs in human cancer cells. We expressed mutant-template human telomerase RNAs in prostate (LNCaP) and breast (MCF-7) cancer cell lines. Even a low threshold level of expression of telomerase RNA gene constructs containing various mutant templates, bu...

  2. Telomere Transcripts Target Telomerase in Human Cancer Cells

    Directory of Open Access Journals (Sweden)

    Theresa Kreilmeier

    2016-08-01

    Full Text Available Long non-coding transcripts from telomeres, called telomeric repeat-containing RNA (TERRA, were identified as blocking telomerase activity (TA, a telomere maintenance mechanism (TMM, in tumors. We expressed recombinant TERRA transcripts in tumor cell lines with TA and with alternative lengthening of telomeres (ALT to study effects on TMM and cell growth. Adeno- and lentivirus constructs (AV and LV were established for transient and stable expression of approximately 130 units of telomere hexanucleotide repeats under control of cytomegalovirus (CMV and human RNase P RNA H1 (hH1 promoters with and without polyadenylation, respectively. Six human tumor cell lines either using telomerase or ALT were infected and analyzed for TA levels. Pre-infection cells using telomerase had 1%–3% of the TERRA expression levels of ALT cells. AV and LV expression of recombinant TERRA in telomerase positive cells showed a 1.3–2.6 fold increase in TERRA levels, and a decrease in TA of 25%–58%. Dominant-negative or small hairpin RNA (shRNA viral expression against human telomerase reverse transcriptase (hTERT results in senescence, not induced by TERRA expression. Population doubling time, cell viability and TL (telomere length were not impacted by ectopic TERRA expression. Clonal growth was reduced by TERRA expression in TA but not ALT cell lines. ALT cells were not affected by treatments applied. Established cell models and tools may be used to better understand the role of TERRA in the cell, especially for targeting telomerase.

  3. Telomerase reverse transcriptase (TERT) : promoter mutation and novel function in human cancer

    OpenAIRE

    Liu, Tiantian

    2014-01-01

    Telomerase reverse transcriptase (TERT) is the catalytic component of telomerase, an RNAdependent DNA polymerase responsible for telomere elongation. TERT is transcriptionally repressed in most normal human somatic cells with limited life-span, which contributes to telomerase silence. It is well established that maintenance of telomere length is essential to cellular immortalization and malignant transformation, and predominantly achieved through TERT induction and subsequent t...

  4. TELOMERASE ACTIVITY IN HUMAN GASTRIC AND COLORECTAL CANCER AND SURROUNDING TISSUES

    Institute of Scientific and Technical Information of China (English)

    CHEN Wen; ZHANG Qiao; WAN De-sen; CUN Ling-yun; WU Cheng-qiu; PAN Zhi-zhong

    1999-01-01

    Objective: To study the telomerase activities in human gastric and colorectal tumors. Methods: The telomerase activity was assayed by the telomeric repeat amplification protocol (TRAP) technique. Forty human tumor samples including 9 colonic, 20 rectal and 11gastric carcinomas and their surrounding tissues were used for the detection. Results: Thirty-six out of 40human tumor samples exhibited telomerase activity regardless of the stages or the differentiation of the tumors. However, only 1 out of 39 tumor surrounding tissues showed telomerase activity. Conclusion: Telomerase may be a good diagnosis biomarker for tumor detection.

  5. Telomerase inhibition effectively targets mouse and human AML stem cells and delays relapse following chemotherapy

    DEFF Research Database (Denmark)

    Bruedigam, Claudia; Bagger, Frederik Otzen; Heidel, Florian H.;

    2014-01-01

    priority. Here, we show that targeting telomerase activity eradicates AML LSCs. Genetic deletion of the telomerase subunit Terc in a retroviral mouse AML model induces cell-cycle arrest and apoptosis of LSCs, and depletion of telomerase-deficient LSCs is partially rescued by p53 knockdown. Murine Terc......(-/-) LSCs express a specific gene expression signature that can be identified in human AML patient cohorts and is positively correlated with patient survival following chemotherapy. In xenografts of primary human AML, genetic or pharmacological inhibition of telomerase targets LSCs, impairs leukemia...... progression, and delays relapse following chemotherapy. Altogether, these results establish telomerase inhibition as an effective strategy for eliminating AML LSCs....

  6. Correlation between expression of human telomerase subunits and telomerase activity in esophageal squamous cell carcinoma

    Institute of Scientific and Technical Information of China (English)

    Chun Li; Ming-Yao Wu; Ying-Rui Liang; Xian-Ying Wu

    2003-01-01

    AIM: To investigate telomerase activity and hTERT, TP-1 expression and their relationships in esophageal squamouscell carcinoma (ESCC).METHODS: Telomerase activity was measured in 60 ESCCtissues using telomeric repeat amplification protocol (TRAP)assay by silver staining. In situ hybridization was used for detecting hTERT and TP-lmRNA.RESULTS: The telomerase activity was detected in 83.3 % of ESCC tissues. The difference of telomerase activity was significant between well and poorly cancer differentiated lesions (P<0.05). The positive rate of telomerase activity was higher in patients with lymphatic metastasis than in patients without lymphatic metastasis. In cancer tissues hTERT mRNA expression was 75 % and TP-1 mRNA expression was 71.7 %. The expression of hTERT, TP-1 mRNA in well and poorly differentiated carcinoma was not significant. The expression of hTERT mRNA was correlated with telomerase activity, but TP-1 mRNA expression was not correlated with it.CONCLUSION: Telomerase activity and hTERT, TP-1 mRNA expression are up-regulated in ESCC. Telomerase activity in ESCC is correlated with lymphatic metastasis and cancer differentiation. Telomerase activity may be used as a prognostic marker in ESCC. hTERT mRNA expression is correlated with telomerase activity. Enhanced hTERT mRNA expression may initially comprehend the telomerase activity level, but it is less sensitive than TRAP assay.

  7. Telomerase activity and cell apoptosis in colon cancer cell by human telomerase reverse transcriptase gene antisense oligodeoxynucleotide

    Institute of Scientific and Technical Information of China (English)

    Ying-An Jiang; He-Sheng Luo; You-Yuan Zhang; Li-Fang Fan; Chong-Qing Jiang; Wei-Jin Chen

    2003-01-01

    AIM: To evaluate the effect of human telomerase reverse transcriptase (hTERT) gene antisense oligodeoxynudeotide (As-ODN) on telomerase activity and cell apoptosis in colon cancer cell line SW480.METHODS: As-ODN was transfected into cells SW480 by liposomal transfection. Cultured cells were divided into three groups: ASODN (5′GGAGCGCGCGGCATCGCGGG-3), sense oligodeoxynucleotide (5′-CCCGCGATGCCGCGCGCTCC-3; SODN) and control. The concentration of oligodeoxynucleotide and lipsome was 10 μmol/L and 16 mg/L, respectively. The activity of telomerase was examined by telomeric repeat amplification protocol (TRAP)-enzyme-linked immunosorbent assay (ELISA), and cell apoptosis was observed by morphology and flow cytometry in each group.RESULTS: Telomerase activity began to be down-regulated or inhibited when cells SW480 were treated with As-ODN for 72 h, and cell apoptosis was induced.CONCLUSION: It is suggested that hTERT As-ODN might specially inhibit the activity of telomerase in colon cancer cells and it is further proved that the hTERT gene has a significant correlation with telomerase activity. Further evidence is needed to prove whether hTERT As-ODN is a potential tool for the treatment of colon cancer.

  8. Quantitation of telomerase components and hTERT mRNA splicing patterns in immortal human cells

    OpenAIRE

    Yi, Xiaoming; Jerry W Shay; Wright, Woodring E.

    2001-01-01

    Telomerase is a reverse transcriptase that adds telomeric repeats to chromosomal ends. In most normal human somatic cells, telomerase is repressed and telomeres progressively shorten, leading to limited proliferative life-span. Telomerase reactivation is associated with cellular immortalization and is a frequent event during tumorigenesis. The telomerase ribonucleoprotein complex consists of two essential components, a catalytic protein subunit [human telomerase reverse transcriptase (hTERT)]...

  9. Combination of telomerase antisense oligonucleotides simultaneously targeting hTR and hTERT produces synergism of inhibition of telomerase activity and growth in human colon cancer cell line

    OpenAIRE

    FU, XIAO-HUA; Zhang, Jian-Song; Zhang, Na; Zhang, Yang-de

    2005-01-01

    AIM: To investigate synergism of inhibition of telomerase activity and proliferation of human colon cancer cells by combination of telomerase antisense oligonucleotides (ASODNs) simultaneously targeting human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT) in vitro.

  10. Telomere Lengths and Telomerase Activity in Dog Tissues: A Potential Model System to Study Human Telomere and Telomerase Biology

    Directory of Open Access Journals (Sweden)

    Lubna Nasir

    2001-01-01

    Full Text Available Studies on telomere and telomerase biology are fundamental to the understanding of aging and age-related diseases such as cancer. However, human studies have been hindered by differences in telomere biology between humans and the classical murine animal model system. In this paper, we describe basic studies of telomere length and telomerase activity in canine normal and neoplastic tissues and propose the dog as an alternative model system. Briefly, telomere lengths were measured in normal canine peripheral blood mononuclear cells (PBMCs, a range of normal canine tissues, and in a panel of naturally occurring soft tissue tumours by terminal restriction fragment (TRF analysis. Further, telomerase activity was measured in canine cell lines and multiple canine tissues using a combined polymerase chain reaction/enzyme-linked immunosorbent assay method. TRF analysis in canine PBMCs and tissues demonstrated mean TRF lengths to range between 12 and 23 kbp with heterogeneity in telomere lengths being observed in a range of normal somatic tissues. In soft tissue sarcomas, two subgroups were identified with mean TRFs of 22.2 and 18.2 kbp. Telomerase activity in canine tissue was present in tumour tissue and testis with little or no activity in normal somatic tissues. These results suggest that the dog telomere biology is similar to that in humans and may represent an alternative model system for studying telomere biology and telomerase-targeted anticancer therapies.

  11. Targeting telomerase and DNA repair in human cancers

    International Nuclear Information System (INIS)

    Telomerase reactivation is essential for telomere maintenance in human cancer cells ensuring indefinite proliferation. Targeting telomere homeostasis has become one of the promising strategies in the therapeutic management of tumours. One major potential drawback, however, is the time lag between telomerase inhibition and critically shortened telomeres triggering cell death, allowing cancer cells to acquire drug resistance. Numerous studies over the last decade have highlighted the role of DNA repair proteins such as Poly (ADP-Ribose) Polymerase-1 (PARP-1), and DNA-dependent protein kinase (DNA-PKcs) in the maintenance of telomere homoeostasis. Dysfunctional telomeres, resulting from the loss of telomeric DNA repeats or the loss of function of telomere-associated proteins trigger DNA damage responses similar to that observed for double strand breaks. We have been working on unravelling such synthetic lethality in cancer cells and this talk would be on one such recently concluded study that demonstrates that inhibition of DNA repair pathways, i.e., NHEJ pathway and that of telomerase could be an alternative strategy to enhance anti-tumour effects and circumvent the possibility of drug resistance. (author)

  12. Elevated Human telomerase reverse transcriptase gene expression in blood cells associated with chronic and arsenic exposure in Inner Mongolia, China

    Science.gov (United States)

    BACKGROUND: Arsenic exposure is associated with human cancer. Telomerase containing the catalytic subunit, human telomerase reverse transcriptase (hTERT), can extend telomeres of chromosomes, delay senescence and promoting cell proliferation leading to tumorigenesis. OBJECTIVE:...

  13. Leptin upregulates telomerase activity and transcription of human telomerase reverse transcriptase in MCF-7 breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Ren, He, E-mail: herenrh@yahoo.com.cn [Key Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education, Tianjin Medical University Cancer Hospital, Tianjin (China); Zhao, Tiansuo; Wang, Xiuchao; Gao, Chuntao; Wang, Jian; Yu, Ming [Key Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education, Tianjin Medical University Cancer Hospital, Tianjin (China); Hao, Jihui, E-mail: jihuihao@yahoo.com [Key Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education, Tianjin Medical University Cancer Hospital, Tianjin (China)

    2010-03-26

    The aim was to analyze the mechanism of leptin-induced activity of telomerase in MCF-7 breast cancer cells. We found that leptin activated telomerase in a dose-dependent manner; leptin upregulated the expression of Human Telomerase Reverse Transcriptase (hTERT) at mRNA and protein levels; blockade of signal transducer and activator of transcription 3 (STAT3) phosphorylation significantly counteracted leptin-induced hTERT transcription and protein expression; chromatin immunoprecipitation analysis showed that leptin enhanced the binding of STAT3 to the hTERT promoter. This study uncovers a new mechanism of the proliferative effect of leptin on breast cancer cells and provides a new explanation of obesity-related breast cancer.

  14. Leptin upregulates telomerase activity and transcription of human telomerase reverse transcriptase in MCF-7 breast cancer cells

    International Nuclear Information System (INIS)

    The aim was to analyze the mechanism of leptin-induced activity of telomerase in MCF-7 breast cancer cells. We found that leptin activated telomerase in a dose-dependent manner; leptin upregulated the expression of Human Telomerase Reverse Transcriptase (hTERT) at mRNA and protein levels; blockade of signal transducer and activator of transcription 3 (STAT3) phosphorylation significantly counteracted leptin-induced hTERT transcription and protein expression; chromatin immunoprecipitation analysis showed that leptin enhanced the binding of STAT3 to the hTERT promoter. This study uncovers a new mechanism of the proliferative effect of leptin on breast cancer cells and provides a new explanation of obesity-related breast cancer.

  15. Human Specific Regulation of the Telomerase Reverse Transcriptase Gene

    Directory of Open Access Journals (Sweden)

    Fan Zhang

    2016-06-01

    Full Text Available Telomerase, regulated primarily by the transcription of its catalytic subunit telomerase reverse transcriptase (TERT, is critical for controlling cell proliferation and tissue homeostasis by maintaining telomere length. Although there is a high conservation between human and mouse TERT genes, the regulation of their transcription is significantly different in these two species. Whereas mTERT expression is widely detected in adult mice, hTERT is expressed at extremely low levels in most adult human tissues and cells. As a result, mice do not exhibit telomere-mediated replicative aging, but telomere shortening is a critical factor of human aging and its stabilization is essential for cancer development in humans. The chromatin environment and epigenetic modifications of the hTERT locus, the binding of transcriptional factors to its promoter, and recruitment of nucleosome modifying complexes all play essential roles in restricting its transcription in different cell types. In this review, we will discuss recent progress in understanding the molecular mechanisms of TERT regulation in human and mouse tissues and cells, and during cancer development.

  16. Detection of telomerase activity in malignant neoplasms and nonmalignantepithelial tissues of human esophagus

    Institute of Scientific and Technical Information of China (English)

    Shah Min Yang; Tian Jiao Wang; Bao Yu Li; Yuan Huan Wu

    2000-01-01

    AIM To study the expression of telomerase activity in malignant esophageal neoplasms and normal humanesophageal epithelia.METHODS Telomerase activity was assayed by the telomere repeat amplification protocol (TRAP)method. All the neoplasms and epithelia of esophagus were confirmed by routine pathological diagnosis.RESULTS Telomerase activity was assayed in 18 normal esophageal epithelial tissues and in 35 malignantneoplasms of esophagus, including 27 cases of esophageal carcinoma and 8 cases of cardiac carcinoma.Telomerase activity was detected in most of malignant neoplasms of esophagus (91.4%, 32/35) and in allthe normal esophageal epithelial tissues except one (18/19).CONCLUSION The results suggest that in addition to contributing to proliferation of immortal blast cellsand neoplastic cells, telomerase activity may also play a similar role in regeneration of normal epithelia ofhuman esophagus. The potential use of telomerase activity as a diagnostic marker in human esophagealneoplasm might not be suitable.

  17. Disease-Associated Human Telomerase RNA Variants Show Loss of Function for Telomere Synthesis without Dominant-Negative Interference▿

    OpenAIRE

    Errington, Timothy M.; Fu, Dragony; Wong, Judy M. Y.; Collins, Kathleen

    2008-01-01

    Telomerase adds simple-sequence repeats to chromosome ends to offset the terminal sequence loss inherent in each cycle of genome replication. Inherited mutations in genes encoding subunits of the human telomerase holoenzyme give rise to disease phenotypes including hematopoietic failure and pulmonary fibrosis. Disease-associated variants of the human telomerase RNA are expressed in heterozygous combination with wild-type telomerase RNA. Here, we exploit a sensitized human primary cell assay s...

  18. Functional Multimerization of the Human Telomerase Reverse Transcriptase

    OpenAIRE

    Beattie, Tara L.; Zhou, Wen; Robinson, Murray O.; Harrington, Lea

    2001-01-01

    The telomerase enzyme exists as a large complex (∼1,000 kDa) in mammals and at minimum is composed of the telomerase RNA and the catalytic subunit telomerase reverse transcriptase (TERT). In Saccharomyces cerevisiae, telomerase appears to function as an interdependent dimer or multimer in vivo (J. Prescott and E. H. Blackburn, Genes Dev. 11:2790–2800, 1997). However, the requirements for multimerization are not known, and it remained unclear whether telomerase exists as a multimer in other or...

  19. Telomerase activity, estrogen receptors (α, β), Bcl-2 expression in human breast cancer and treatment response

    International Nuclear Information System (INIS)

    The mechanism for maintaining telomere integrity is controlled by telomerase, a ribonucleoprotein enzyme that specifically restores telomere sequences, lost during replication by means of an intrinsic RNA component as a template for polymerization. Among the telomerase subunits, hTERT (human telomerase reverse transcriptase) is expressed concomitantly with the activation of telomerase. The role of estrogens and their receptors in the transcriptional regulation of hTERT has been demonstrated. The current study determines the possible association between telomerase activity, the expression of both molecular forms of estrogen receptor (ERα and ERβ) and the protein bcl-2, and their relative associations with clinical parameters. Tissue samples from 44 patients with breast cancer were used to assess telomerase activity using the TRAP method and the expression of ERα, ERβ and bcl-2 by means of immunocytochemical techniques. Telomerase activity was detected in 59% of the 44 breast tumors examined. Telomerase activity ranged from 0 to 49.93 units of total product generated (TPG). A correlation was found between telomerase activity and differentiation grade (p = 0.03). The only significant independent marker of response to treatment was clinical stage. We found differences between the frequency of expression of ERα (88%) and ERβ (36%) (p = 0.007); bcl-2 was expressed in 79.5% of invasive breast carcinomas. We also found a significant correlation between low levels of telomerase activity and a lack of ERβ expression (p = 0.03). Lower telomerase activity was found among tumors that did not express estrogen receptor beta. This is the first published study demonstrating that the absence of expression of ERβ is associated with low levels of telomerase activity

  20. Competing endogenous RNA and interactome bioinformatic analyses on human telomerase.

    Science.gov (United States)

    Arancio, Walter; Pizzolanti, Giuseppe; Genovese, Swonild Ilenia; Baiamonte, Concetta; Giordano, Carla

    2014-04-01

    We present a classic interactome bioinformatic analysis and a study on competing endogenous (ce) RNAs for hTERT. The hTERT gene codes for the catalytic subunit and limiting component of the human telomerase complex. Human telomerase reverse transcriptase (hTERT) is essential for the integrity of telomeres. Telomere dysfunctions have been widely reported to be involved in aging, cancer, and cellular senescence. The hTERT gene network has been analyzed using the BioGRID interaction database (http://thebiogrid.org/) and related analysis tools such as Osprey (http://biodata.mshri.on.ca/osprey/servlet/Index) and GeneMANIA (http://genemania.org/). The network of interaction of hTERT transcripts has been further analyzed following the competing endogenous (ce) RNA hypotheses (messenger [m] RNAs cross-talk via micro [mi] RNAs) using the miRWalk database and tools (www.ma.uni-heidelberg.de/apps/zmf/mirwalk/). These analyses suggest a role for Akt, nuclear factor-κB (NF-κB), heat shock protein 90 (HSP90), p70/p80 autoantigen, 14-3-3 proteins, and dynein in telomere functions. Roles for histone acetylation/deacetylation and proteoglycan metabolism are also proposed. PMID:24713059

  1. Human telomerase reverse transcriptase (hTERT Q169 is essential for telomerase function in vitro and in vivo.

    Directory of Open Access Journals (Sweden)

    Haley D M Wyatt

    Full Text Available BACKGROUND: Telomerase is a reverse transcriptase that maintains the telomeres of linear chromosomes and preserves genomic integrity. The core components are a catalytic protein subunit, the telomerase reverse transcriptase (TERT, and an RNA subunit, the telomerase RNA (TR. Telomerase is unique in its ability to catalyze processive DNA synthesis, which is facilitated by telomere-specific DNA-binding domains in TERT called anchor sites. A conserved glutamine residue in the TERT N-terminus is important for anchor site interactions in lower eukaryotes. The significance of this residue in higher eukaryotes, however, has not been investigated. METHODOLOGY/PRINCIPAL FINDINGS: To understand the significance of this residue in higher eukaryotes, we performed site-directed mutagenesis on human TERT (hTERT Q169 to create neutral (Q169A, conservative (Q169N, and non-conservative (Q169D mutant proteins. We show that these mutations severely compromise telomerase activity in vitro and in vivo. The functional defects are not due to abrogated interactions with hTR or telomeric ssDNA. However, substitution of hTERT Q169 dramatically impaired the ability of telomerase to incorporate nucleotides at the second position of the template. Furthermore, Q169 mutagenesis altered the relative strength of hTERT-telomeric ssDNA interactions, which identifies Q169 as a novel residue in hTERT required for optimal primer binding. Proteolysis experiments indicate that Q169 substitution alters the protease-sensitivity of the hTERT N-terminus, indicating that a conformational change in this region of hTERT is likely critical for catalytic function. CONCLUSIONS/SIGNIFICANCE: We provide the first detailed evidence regarding the biochemical and cellular roles of an evolutionarily-conserved Gln residue in higher eukaryotes. Collectively, our results indicate that Q169 is needed to maintain the hTERT N-terminus in a conformation that is necessary for optimal enzyme

  2. Expression of telomerase activity and oxidative stress in human hepatocellular carcinoma with cirrhosis

    Institute of Scientific and Technical Information of China (English)

    Dao-Yong Liu; Zhi-Hai Peng; Guo-Qiang Qiu; Chong-Zhi Zhou

    2003-01-01

    AIM: To study the expression and significance of telomerase activity and oxidative stress in hepatocellular carcinoma (HCC) with cirrhosis.METHODS: In this study, TRAP-ELISA assay was used to determine telomerase activity in 21 cases of HCC as well as in 23 cases of hepatic cirrhosis. Malondialdehyde(MDA),glutathione S-transferase (GST) and total anti-oxidative capacity (T-AOC) were also examined in the same samples with human MDA, GST and T-AOC kits.RESULTS: Eighteen of 21 cases of HCC were found to have increased telomerase activity, whereas only three of the 23non-cancerous cirrhotic samples were found to have weak telomerase activity, and the difference was significant (P<0.001). No significant difference in telomerase activity was detected according to different tumor size, tumor stage,histological grade, HBsAg, contents of albumin, bilirubin,ALT, AFP, r-GT and platelet. There were significant differences between HCC and cirrhosis in the expression of MDA, GST and T-AOC respectively. Telomerase activity correlated positively with the content of MDA (P<0.05).CONCLUSION: Telomerase activation is the early event of carcinogenesis, which is not correlated with clinicopathological factors of HCC. The dysfunction of the anti-oxidative system is closely correlated with the progression from cirrhosis to hepatocellular carcinoma. Oxidative stress may contribute partly to telomerase activation.

  3. Is telomerase reactivation associated with the down-regulation of TGF β receptor-II expression in human breast cancer?

    Directory of Open Access Journals (Sweden)

    Thomas Valene

    2003-07-01

    Full Text Available Abstract Background Telomerase is a ribonucleoprotein that synthesizes telomeres and plays an important role in chromosomal stability and cellular immortalisation. Telomerase activity is detectable in most human cancers but not in normal somatic cells. TGF beta (transforming growth factor beta is a member of a family of cytokines that are essential for cell survival and seems to be down-regulated in human cancer. Recent in vitro work using human breast cancer cell lines has suggested that TGF beta down-regulates the expression of hTERT (human telomerase reverse transcriptase : the catalytic subunit of telomerase. We have therefore hypothesised that telomerase reactivation is associated with reduced immunohisto-chemical expression of TGF beta type II receptor (RII in human breast cancer. Methods TGF beta RII immunohistochemical expression was determined in 24 infiltrating breast carcinomas with known telomerase activity (17 telomerase-positive and 7 telomerase-negative. Immunohistochemical expression of TGF beta RII was determined by a breast pathologist who was blinded to telomerase data. Results TGF beta RII was detected in all lesions. The percentage of stained cells ranged from 1–100%. The difference in TGF beta RII expression between telomerase positive and negative tumours was not statistically significant (p = 1.0. Conclusion The results of this pilot study suggest that there is no significant association between telomerase reactivation and TGF-beta RII down-regulation in human breast cancer.

  4. MNS16A tandem repeats minisatellite of human telomerase gene: a risk factor for colorectal cancer

    OpenAIRE

    Hofer, Philipp; Baierl, Andreas; Feik, Elisabeth; Führlinger, Gerhard; Leeb, Gernot; Mach, Karl; Holzmann, Klaus; Micksche, Michael; Gsur, Andrea

    2011-01-01

    Telomerase reactivation and expression of human telomerase gene [human telomerase reverse transcriptase (hTERT)] are hallmarks of unlimited proliferation potential of cancer cells. A polymorphic tandem repeats minisatellite of hTERT gene, termed MNS16A was reported to influence hTERT expression. To assess the role of MNS16A as potential biomarker for colorectal cancer (CRC), we investigated for the first time the association of MNS16A genotypes with risk of colorectal polyps and CRC. In the o...

  5. Telomerase repeat amplification protocol (TRAP) activity upon recombinant expression and purification of human telomerase in a bacterial system.

    Science.gov (United States)

    Hansen, Debra T; Thiyagarajan, Thirumagal; Larson, Amy C; Hansen, Jeffrey L

    2016-07-01

    Telomerase biogenesis is a highly regulated process that solves the DNA end-replication problem. Recombinant expression has so far been accomplished only within a eukaryotic background. Towards structural and functional analyses, we developed bacterial expression of human telomerase. Positive activity by the telomerase repeat amplification protocol (TRAP) was identified in cell extracts of Escherichia coli expressing a sequence-optimized hTERT gene, the full-length hTR RNA with a self-splicing hepatitis delta virus ribozyme, and the human heat shock complex of Hsp90, Hsp70, p60/Hop, Hsp40, and p23. The Hsp90 inhibitor geldanamycin did not affect post-assembly TRAP activity. By various purification methods, TRAP activity was also obtained upon expression of only hTERT and hTR. hTERT was confirmed by tandem mass spectrometry in a ∼120 kDa SDS-PAGE fragment from a TRAP-positive purification fraction. TRAP activity was also supported by hTR constructs lacking the box H/ACA small nucleolar RNA domain. End-point TRAP indicated expression levels within 3-fold of that from HeLa carcinoma cells, which is several orders of magnitude below detection by the direct assay. These results represent the first report of TRAP activity from a bacterium and provide a facile system for the investigation of assembly factors and anti-cancer therapeutics independently of a eukaryotic setting. PMID:26965413

  6. Attenuation of Telomerase Activity by siRNA Targeted Telomerase RNA Leads to Apoptosis and Inhibition of Proliferation in Human Renal Carcinoma Cells

    Institute of Scientific and Technical Information of China (English)

    Rumin Wen; Junjie Liu; Wang Li; Wenfa Yang; Lijun Mao; Junnian Zheng

    2006-01-01

    OBJECTIVE Telomerase is an attractive molecular target for cancer therapy because the activation of telomerase is one of the key steps in cell immortalization and carcinogenesis. RNA interference using small-interfering RNA (siRNA) has been demonstrated to be an effective method for inhibiting the expression of a given gene in human cells. The aim of the present study was to investigate whether inhibition of telomerase activity by siRNA targeted against human telomerase RNA (hTR) can inhibit proliferation and induce apoptotic cell death in human renal carcinoma cells(HRCCs).METHODS The siRNA duplexes for hTR were synthesized and 786-O HRCCs were transfected with different concentrations of hTR-siRNA. The influence on the hTR mRNA level, telomerase activity, as well as the effect on cell proliferation and apoptosis was examined.RESULTS Anti-hTR siRNA treatment of HRCCs resulted in specific reduction of hTR mRNA and inhibition of telomerase activity. Additionally,significant inhibition of proliferation and induction of apoptosis were observed.CONCLUSION siRNA against the hTR gene can inhibit proliferation and induce apoptosis by blocking telomerase activity of HRCCs. Specific hTR inhibition by siRNA represents a promising new option for renal cancer treatment.

  7. Tissue distribution and engraftment of human mesenchymal stem cells immortalized by human telomerase reverse transcriptase gene

    DEFF Research Database (Denmark)

    Bentzon, J.F.; Stenderup, K.; Hansen, F.D.;

    2005-01-01

    Engraftment of mesenchymal stem cells (MSC) in peripheral tissues for replenishing of local stem cell function has been proposed as a therapeutic approach to degenerative diseases. We have previously reported the development of an immortalized human telomerase reverse transcriptase transduced MSC...

  8. Transforming growth factor beta mediates the progesterone suppression of an epithelial metalloproteinase by adjacent stroma in the human endometrium.

    OpenAIRE

    Bruner, K L; Rodgers, W H; Gold, L I; Korc, M.; Hargrove, J T; Matrisian, L. M.; Osteen, K.G.

    1995-01-01

    Unlike most normal adult tissues, cyclic growth and tissue remodeling occur within the uterine endometrium throughout the reproductive years. The matrix metalloproteinases (MMPs), a family of structurally related enzymes that degrade specific components of the extracellular matrix are thought to be the physiologically relevant mediators of extracellular matrix composition and turnover. Our laboratory has identified MMPs of the stromelysin family in the cycling human endometrium, implicating t...

  9. Telomerase: The Devil Inside

    Directory of Open Access Journals (Sweden)

    Mukesh Kumar

    2016-07-01

    Full Text Available High telomerase activity is detected in nearly all human cancers but most human cells are devoid of telomerase activity. There is well-documented evidence that reactivation of telomerase occurs during cellular transformation. In humans, tumors can rely in reactivation of telomerase or originate in a telomerase positive stem/progenitor cell, or rely in alternative lengthening of telomeres, a telomerase-independent telomere-length maintenance mechanism. In this review, we will focus on the telomerase positive tumors. In this context, the recent findings that telomerase reverse transcriptase (TERT promoter mutations represent the most common non-coding mutations in human cancer have flared up the long-standing discussion whether cancer originates from telomerase positive stem cells or telomerase reactivation is a final step in cellular transformation. Here, we will discuss the pros and cons of both concepts in the context of telomere length-dependent and telomere length-independent functions of telomerase. Together, these observations may provoke a re-evaluation of telomere and telomerase based therapies, both in telomerase inhibition for cancer therapy and telomerase activation for tissue regeneration and anti-ageing strategies.

  10. Telomerase: The Devil Inside.

    Science.gov (United States)

    Kumar, Mukesh; Lechel, Andre; Güneş, Çagatay

    2016-01-01

    High telomerase activity is detected in nearly all human cancers but most human cells are devoid of telomerase activity. There is well-documented evidence that reactivation of telomerase occurs during cellular transformation. In humans, tumors can rely in reactivation of telomerase or originate in a telomerase positive stem/progenitor cell, or rely in alternative lengthening of telomeres, a telomerase-independent telomere-length maintenance mechanism. In this review, we will focus on the telomerase positive tumors. In this context, the recent findings that telomerase reverse transcriptase (TERT) promoter mutations represent the most common non-coding mutations in human cancer have flared up the long-standing discussion whether cancer originates from telomerase positive stem cells or telomerase reactivation is a final step in cellular transformation. Here, we will discuss the pros and cons of both concepts in the context of telomere length-dependent and telomere length-independent functions of telomerase. Together, these observations may provoke a re-evaluation of telomere and telomerase based therapies, both in telomerase inhibition for cancer therapy and telomerase activation for tissue regeneration and anti-ageing strategies. PMID:27483324

  11. Two-step mechanism involving active-site conformational changes regulates human telomerase DNA binding.

    Science.gov (United States)

    Tomlinson, Christopher G; Moye, Aaron L; Holien, Jessica K; Parker, Michael W; Cohen, Scott B; Bryan, Tracy M

    2015-01-15

    The ribonucleoprotein enzyme telomerase maintains telomeres and is essential for cellular immortality in most cancers. Insight into the telomerase mechanism can be gained from syndromes such as dyskeratosis congenita, in which mutation of telomerase components manifests in telomere dysfunction. We carried out detailed kinetic and thermodynamic analyses of wild-type telomerase and two disease-associated mutations in the reverse transcriptase domain. Differences in dissociation rates between primers with different 3' ends were independent of DNA affinities, revealing that initial binding of telomerase to telomeric DNA occurs through a previously undescribed two-step mechanism involving enzyme conformational changes. Both mutations affected DNA binding, but through different mechanisms: P704S specifically affected protein conformational changes during DNA binding, whereas R865H showed defects in binding to the 3' region of the DNA. To gain further insight at the structural level, we generated the first homology model of the human telomerase reverse transcriptase domain; the positions of P704S and R865H corroborate their observed mechanistic defects, providing validation for the structural model. Our data reveal the importance of protein interactions with the 3' end of telomeric DNA and the role of protein conformational change in telomerase DNA binding, and highlight naturally occurring disease mutations as a rich source of mechanistic insight. PMID:25365545

  12. Human tumor-released microvesicles promote the differentiation of myeloid cells with transforming growth factor-beta-mediated suppressive activity on T lymphocytes.

    Science.gov (United States)

    Valenti, Roberta; Huber, Veronica; Filipazzi, Paola; Pilla, Lorenzo; Sovena, Gloria; Villa, Antonello; Corbelli, Alessandro; Fais, Stefano; Parmiani, Giorgio; Rivoltini, Licia

    2006-09-15

    Human tumors constitutively release endosome-derived microvesicles, transporting a broad array of biologically active molecules with potential modulatory effects on different immune cells. Here, we report the first evidence that tumor-released microvesicles alter myeloid cell function by impairing monocyte differentiation into dendritic cells and promoting the generation of a myeloid immunosuppressive cell subset. CD14+ monocytes isolated from healthy donors and differentiated with interleukin (IL)-4 and granulocyte macrophage colony-stimulating factor in the presence of tumor-derived microvesicles turned into HLA-DR(-/low) cells, retaining CD14 expression and failing to up-regulate costimulatory molecules, such as CD80 and CD86. These phenotypic changes were paralleled by a significant release of different cytokines, including IL-6, tumor necrosis factor-alpha, and transforming growth factor-beta (TGF-beta), and a dose-dependent suppressive activity on activated T-cell-proliferation and cytolytic functions, which could be reversed by anti-TGF-beta-neutralizing antibodies. Microvesicles isolated from plasma of advanced melanoma patients, but not from healthy donors, mediated comparable effects on CD14+ monocytes, skewing their differentiation toward CD14+HLA-DR-/low cells with TGF-beta-mediated suppressive activity on T-cell-functions. Interestingly, a subset of TGF-beta-secreting CD14+HLA-DR- cells mediating suppressive activity on T lymphocytes was found to be significantly expanded in peripheral blood of melanoma patients compared with healthy donors. These data suggest the development in cancer patients of an immunosuppressive circuit by which tumors promote the generation of suppressive myeloid cells through the release of circulating microvesicles and without the need for cell-to-cell contact. Therapeutic interventions on the crucial steps of this pathway may contribute to restore tumor/immune system interactions favoring T-cell-mediated control of tumor

  13. TIN2-tethered TPP1 recruits human telomerase to telomeres in vivo.

    OpenAIRE

    Abreu, E.; Aritonovska, E.; Reichenbach, P.; Cristofari, G.; Culp, B.; Terns, R. M.; Lingner, J; Terns, M P

    2010-01-01

    Recruitment to telomeres is a pivotal step in the function and regulation of human telomerase; however, the molecular basis for recruitment is not known. Here, we have directly investigated the process of telomerase recruitment via fluorescence in situ hybridization (FISH) and chromatin immunoprecipitation (ChIP). We find that depletion of two components of the shelterin complex that is found at telomeres--TPP1 and the protein that tethers TPP1 to the complex, TIN2--results in a loss of telom...

  14. Telomerase activity and telomere length in human hepatocellular carcinoma.

    Science.gov (United States)

    Huang, G T; Lee, H S; Chen, C H; Chiou, L L; Lin, Y W; Lee, C Z; Chen, D S; Sheu, J C

    1998-11-01

    Telomerase activity is activated and telomere length altered in various types of cancers, including hepatocellular carcinoma (HCC). A total of 39 HCC tissues and the corresponding non-tumour livers were analysed and correlated with clinical parameters. Telomere length was determined by terminal restriction fragment assay, and telomerase activity was assayed by telomeric repeat amplification protocol. Telomerase activity was positive in 24 of the 39 tumour tissues (1.15-285.13 total product generated (TPG) units) and in six of the 39 non-tumour liver tissues (1.05-1.73 TPG units). In the 28 cases analysed for telomere length, telomere length was shortened in 11 cases, lengthened in six cases, and unaltered in 11 cases compared with non-tumour tissues. Neither telomere length nor telomerase activity was correlated to any clinical parameters. PMID:10023320

  15. An antiapoptotic role for telomerase RNA in human immune cells independent of telomere integrity or telomerase enzymatic activity

    OpenAIRE

    Gazzaniga, Francesca S.; Elizabeth H. Blackburn

    2014-01-01

    Telomerase RNA component hTR, but not the core enzymatic protein component hTERT, protects T cells from apoptosis.hTR prevents dexamethasone-induced apoptosis specifically when in a telomerase enzymatically inactive state.

  16. Inhibition on Telomerase Activity and Cytotoxic Effects by Cisplatin in Cultured Human Choroidal Melanoma Cells

    Institute of Scientific and Technical Information of China (English)

    Hao Cheng; Zhongyao Wu; Jianliang Zheng; Guilan Lu; Jianhua Yan; Min Liu; Danping Huang; Jianxian Lin

    2003-01-01

    Purpose: To study the changes of telomerase activity and cytotoxic effects by Cisplatin;cis-dichlorodiamine platinum (CDDP) in cultured human choroidal melanoma.Material and Methods: The primary cultured human choroidal melanoma cells werecultured in the presence and absence of CDDP with different concentration and timerespectively. The toxic effects were evaluated by MTT and the level of telormarse wasdetected by PCR-ELISA assay. And the relationship between telomerase activity andcytotoxic effects were analyzed by a correlation analysis.Results: Following the increase of the concentration and the time of CDDP, graduallyrepressed telomerase activity was detected in cultured cells. Meanwhile, the restrain rateof the cells increased. The telomerase activity at 24h and 1μg/ml was repressedsignificantly compared with the control cells. However, the appearance of cell deathlagged behind the decreasing of telomerase.Conclusions: CDDP is an effective telomerase inhibitor in cultured choroidal melanomacells of human eyes, which presents concentration and time dependency and can causethe death of cultured cells.

  17. Studying the Anti-aging Effect of Human Growth Hormone on Human Fibroblast Cells via Telomerase Activity

    Directory of Open Access Journals (Sweden)

    Nader Chaparzadeh

    2010-01-01

    Full Text Available Objective: In recent years, studies have focused on the telomerase for cancer treatmentby repressing telomerase in cancerous cells or prevent cell aging by activating it in theaged cells. Thus, in these studies natural and synthetic agents have been used to repressor activate telomerase. In this research, we investigated the effects of human growth hormone(hGH on aging via evaluation of telomerase activity.Materials and Methods: Primary human foreskin fibroblast cells were isolated, culturedand treated with different concentrations of hGH. BrdU and MTT cell proliferation assaysand cells number counting. Cell aging was assayed by the senescence sensitivegalactosidase staining method. Telomerase activity was measured with a telomerasePCR ELISA kit.Data were analyzed with SPSS software (one-way ANOVA and univariateANOVA.Results: Our results indicated that cells treated with a lower concentration (0.1, 1 ng/mlof hGH had more green color cells (aged cells. Furthermore, cell proliferation increasedwith increasing hGH concentrations (10 to 100 ng/ml which was significant in comparisonwith untreated control cells. TRAP assay results indicated that telomerase activityincreased with increasing hGH concentration, but there was no significant difference. Additionally,more rapid cell growth and telomerase activity was noted in the absence of H2O2when compared with the presence of H2O2, which was significantly different.Conclusion: Although increasing cell proliferation along with increasing hGH concentrationwas confirmed by all cell proliferation assays, only the cell counting test was statisticallysignificant. Thus, it is inconclusive that hGH (up to 100 ng/ml has an anti-agingeffect. Also, because there was no significant difference in the telomerase activity results(in spite of increasing progress along with increasing hGH concentration we can not certainlyconclude that hGH (up to 100 ng/ml impacts telomerase activity.

  18. Inhibition of telomerase with human telomerase reverse transcriptase antisense enhances tumor necrosis factor-a-induced apoptosis in bladder cancer cells

    Institute of Scientific and Technical Information of China (English)

    GAO Xiao-dong; CHEN Yi-rong

    2007-01-01

    Background Telomerase activity is found in 85%-90% of all human cancers but not in their adjacent normal cells.Human telomerase reverse transcriptase (hTERT) is an essential component in the telomerase complex that plays an important role in telomerase activity. This study investigated the effect of the telomerase inhibition with an hTERT antisense oligodeoxynucleotide (ODN) in bladder cancer cells (T24) on tumor necrosis factor-o (TNF-α)-induced apoptosis.Methods Antisense phosphorothioate oligodeoxynucleotide (AS PS-ODN) was synthesized and purified. Telomerase activity was measured by polymerase chain reaction enzyme-linked immunoassay (PCR-ELISA). hTERT mRNA expression was measured by reverse transcription polymerase chain reaction (RT-PCR) assay and a gel-image system.hTERT protein was detected by immunochemistry and flow cytometry. Cell viability was measured by the 3-(4,5-dimethylthiazol-2-yl)-2, 5-Diphenyltetrazolium (MTT) assay. Cell apoptosis was observed by a morphological method and determined by flow cytometry.Results AS PS-ODN significantly inhibited telomerase activity and decreased the levels of hTERT mRNA which preceded the decline in the telomerase activity. AS PS-ODN significantly reduced the percentage of positive cells expressing hTERT protein following the decline of hTERT mRNA levels. There was no difference seen in the telomerase activity, hTERT mRNA expression or the protein levels between the sense phosphorothioate oligodeoxynucleotide (SPS-ODN) and the control group. AS PS-ODN treatment significantly decreased the cell viability and enhanced the apoptotic rate of T24 cells in response to TNF-α while there was no difference in cell viability and apoptotic rate between the S PS-ODN and the control group.Conclusions AS PS-ODN can significantly inhibit telomerase activity by downregulating the hTERT mRNA and protein expression. Treatment with AS PS-ODN may be a potential and most promising strategy for bladder cancer with telomerase

  19. Transcription Regulation of the Human Telomerase Reverse Transcriptase (hTERT) Gene.

    Science.gov (United States)

    Ramlee, Muhammad Khairul; Wang, Jing; Toh, Wei Xun; Li, Shang

    2016-01-01

    Embryonic stem cells and induced pluripotent stem cells have the ability to maintain their telomere length via expression of an enzymatic complex called telomerase. Similarly, more than 85%-90% of cancer cells are found to upregulate the expression of telomerase, conferring them with the potential to proliferate indefinitely. Telomerase Reverse Transcriptase (TERT), the catalytic subunit of telomerase holoenzyme, is the rate-limiting factor in reconstituting telomerase activity in vivo. To date, the expression and function of the human Telomerase Reverse Transcriptase (hTERT) gene are known to be regulated at various molecular levels (including genetic, mRNA, protein and subcellular localization) by a number of diverse factors. Among these means of regulation, transcription modulation is the most important, as evident in its tight regulation in cancer cell survival as well as pluripotent stem cell maintenance and differentiation. Here, we discuss how hTERT gene transcription is regulated, mainly focusing on the contribution of trans-acting factors such as transcription factors and epigenetic modifiers, as well as genetic alterations in hTERT proximal promoter. PMID:27548225

  20. Transcription Regulation of the Human Telomerase Reverse Transcriptase (hTERT Gene

    Directory of Open Access Journals (Sweden)

    Muhammad Khairul Ramlee

    2016-08-01

    Full Text Available Embryonic stem cells and induced pluripotent stem cells have the ability to maintain their telomere length via expression of an enzymatic complex called telomerase. Similarly, more than 85%–90% of cancer cells are found to upregulate the expression of telomerase, conferring them with the potential to proliferate indefinitely. Telomerase Reverse Transcriptase (TERT, the catalytic subunit of telomerase holoenzyme, is the rate-limiting factor in reconstituting telomerase activity in vivo. To date, the expression and function of the human Telomerase Reverse Transcriptase (hTERT gene are known to be regulated at various molecular levels (including genetic, mRNA, protein and subcellular localization by a number of diverse factors. Among these means of regulation, transcription modulation is the most important, as evident in its tight regulation in cancer cell survival as well as pluripotent stem cell maintenance and differentiation. Here, we discuss how hTERT gene transcription is regulated, mainly focusing on the contribution of trans-acting factors such as transcription factors and epigenetic modifiers, as well as genetic alterations in hTERT proximal promoter.

  1. Relationship between the Expression of Telomerase and Human Papillomavirus Infection in Invasive Uterine Cervical Carcinoma

    Institute of Scientific and Technical Information of China (English)

    SIMA Ni; CAI Liping; ZHU Yuanfang; WANG Wei; WANG Shixuan; MA Ding

    2007-01-01

    Telomerase activity was examined in invasive cervical carcinoma to assess whether it is activated during cervical malignant transformation and to look for its possible association with human papillomavirus (HPV) infection. Histologically confirmed invasive cervical carcinomas and benign cervices were assayed for telomerase activity by using a modified telomere repeat amplification protocol (TRAP). The same cases were subjected to polymerase chain reaction (PCR) detection of HPV by using consensus primers and type-specific (HPV types 16 and 18) primers. Telomerase activity was detected in 40 of 45 (88.9%) invasive cervical carcinomas and 2 (all chronic cervicitis) of 50 (4%) benign cervical lesions. HPV was detected in 36 (24 HPV-16 and 4 HPV-18 cases) of 45 (80%) invasive cervical carcinomas and 20 (11 HPV-16 and 1 HPV-18 cases) of 50 (40%) benign cervical changes. There was a significant correlation between the expression of telomerase with histological grade (φ=0.44, P<0.005), but no correlation was found between telomerase expression and HPV-18 (P>0.05). Although larger sample studies are needed, there seems to be a clear association between telomerase upregulation and HPV status, mainly HPV-16 infection.

  2. Minimized human telomerase maintains telomeres and resolves endogenous roles of H/ACA proteins, TCAB1, and Cajal bodies.

    Science.gov (United States)

    Vogan, Jacob M; Zhang, Xiaozhu; Youmans, Daniel T; Regalado, Samuel G; Johnson, Joshua Z; Hockemeyer, Dirk; Collins, Kathleen

    2016-01-01

    We dissected the importance of human telomerase biogenesis and trafficking pathways for telomere maintenance. Biological stability of human telomerase RNA (hTR) relies on H/ACA proteins, but other eukaryotes use other RNP assembly pathways. To investigate additional rationale for human telomerase assembly as H/ACA RNP, we developed a minimized cellular hTR. Remarkably, with only binding sites for telomerase reverse transcriptase (TERT), minimized hTR assembled biologically active enzyme. TERT overexpression was required for cellular interaction with minimized hTR, indicating that H/ACA RNP assembly enhances endogenous hTR-TERT interaction. Telomere maintenance by minimized telomerase was unaffected by the elimination of the telomerase holoenzyme Cajal body chaperone TCAB1 or the Cajal body scaffold protein Coilin. Surprisingly, wild-type hTR also maintained and elongated telomeres in TCAB1 or Coilin knockout cells, with distinct changes in telomerase action. Overall, we elucidate trafficking requirements for telomerase biogenesis and function and expand mechanisms by which altered telomere maintenance engenders human disease. PMID:27525486

  3. NEK6-mediated phosphorylation of human TPP1 regulates telomere length through telomerase recruitment.

    Science.gov (United States)

    Hirai, Yugo; Tamura, Miki; Otani, Junji; Ishikawa, Fuyuki

    2016-08-01

    Shelterin component TPP1 plays critical roles in chromosome end protection and telomere length regulation. Specifically, TPP1 contains an OB-fold domain that provides an interface to recruit telomerase. However, it remains largely unknown how telomerase recruitment is regulated by cell cycle regulators. We show that TPP1 interacts with the cell cycle regulator kinase NEK6 in human cells. We found that NEK6-mediated phosphorylation of TPP1 Ser255 in G2/M phase regulates the association between telomerase activity and TPP1. Furthermore, we found evidence that POT1 negatively regulates TPP1 phosphorylation because the level of Ser255 phosphorylation was elevated when telomeres were elongated by a POT1 mutant lacking its OB-fold domains. Ser255 is located in the intervening region between the telomerase-recruiting OB-fold and the POT1 recruitment domains. Ser255 and the surrounding amino acids are conserved among vertebrates. These observations suggest that a region adjacent to the OB-fold domain of TPP1 is involved in telomere length regulation via telomerase recruitment. PMID:27396482

  4. Asparagales telomerases which synthesize the human type of telomeres

    Czech Academy of Sciences Publication Activity Database

    Sýkorová, Eva; Leitch, A.R.; Fajkus, Jiří

    2006-01-01

    Roč. 60, č. 5 (2006), s. 633-646. ISSN 0167-4412 R&D Projects: GA ČR(CZ) GP204/04/P105; GA ČR(CZ) GA521/05/0055; GA AV ČR(CZ) IAA600040505 Institutional research plan: CEZ:AV0Z50040507 Keywords : Asparagales * evolution * telomerase Subject RIV: BO - Biophysics Impact factor: 3.577, year: 2006

  5. Asparagales telomerases which synthesize the human type of telomeres

    Czech Academy of Sciences Publication Activity Database

    Sýkorová, Eva; Leitch, Andrew R.; Fajkus, Jiří

    Venice, 2006. P 8.28-P 8.28. [5th Plant Genomics, European Meetings. 11.10.2006-14.10.2006, Venice] R&D Projects: GA ČR(CZ) GP204/04/P105; GA ČR(CZ) GA521/05/0055; GA AV ČR(CZ) IAA600040505 Institutional research plan: CEZ:AV0Z50040507 Keywords : telomerase * evolution * Asparagales Subject RIV: BO - Biophysics

  6. Telomerase promoter reprogramming and interaction with general transcription factors in the human mesenchymal stem cell

    DEFF Research Database (Denmark)

    Serakinci, Nedime; Hoare, Stacey F.; Kassem, Moustapha;

    2006-01-01

    The human adult mesenchymal stem cell (hMSC) does not express telomerase and has been shown to be the target for neoplastic transformation after transduction with hTERT. These findings lend support to the stem cell hypothesis of cancer development but by supplying hTERT, the molecular events...... modifications of the chromatin environment lead to reactivation of telomerase gene expression. It is shown that repression of hTERT expression in hMSCs is due to promoter-specific histone hypoacetylation coupled with low Pol II and TFIIB trafficking. This repression is overcome by treatment with Trichostatin A...

  7. Normal T-cell telomerase activity and upregulation in human immunodeficiency virus-1 infection

    NARCIS (Netherlands)

    Wolthers, KC; Otto, SA; Wisman, GBA; Fleury, S; Reiss, P; ten Kate, RW; van der Zee, AGJ; Miedema, F

    1999-01-01

    In human immunodeficiency virus (HIV)-1 infection, decrease of telomere length is mainly found in CD8(+) T cells and not in CD4(+) T cells. Telomerase, a ribonucleoprotein enzyme that can synthesize telomeric sequence onto chromosomal ends, can compensate for telomere loss. Here, we investigated if

  8. Growth inhibition of BEL-7404 human hepatoma cells by expression of mutant telomerase reverse transcriptase.

    Science.gov (United States)

    Zhang, Rugang; Wang, Xingwang; Guo, Lixia; Xie, Hong

    2002-01-10

    Human hepatocellular carcinoma (HCC) is one of the most common malignancies in Asia and Africa. Human telomerase reverse transcriptase (hTERT) is expressed in HCC but absent in normal human liver cells, which is consistent with the expression pattern of telomerase. In the present study, expression of a dominant-negative form of hTERT (DN-hTERT) resulted in inhibition of telomerase activity and decreased mean telomeric length of BEL-7404 human hepatoma cells, whereas expression of wild-type hTERT (WT-hTERT) and control vector had no such effects. Cell growth was inhibited by this mutant (DN-hTERT), which was consistent with the changes in telomerase level. Flattened large cells were found in late generations with the DN-hTERT treatment. When mean telomeric length of DN-hTERT-transfected cells reached a critical length (about 1.7 kb), apoptosis was induced. Tumorigenicity of DN-hTERT-expressing cells was eliminated in vivo. These data indicated that hTERT was essential for the growth of hepatoma cells. hTERT can also be used as an important target for anti-HCC drug screening. PMID:11774261

  9. Inhibiting effect of antisense hTRT on telomerase activity of human liver cancer cell line SMMC-7721

    Institute of Scientific and Technical Information of China (English)

    牟娇; 李晓冬; 杨庆; 贾凤岐; 卫立辛; 郭亚军; 吴孟超

    2003-01-01

    Objective: To induce changes in biological character of human liver cancer cell line SMMC-7721 by blocking the expression of telomerase genes hTRT and to explore its value in cancer gene therapy. Methods: The vehicle for eukaryotic expression of antisense hTRT was constructed and then transfected into SMMC-7721 cells. The effects of antisense hTRT gene on telomerase activity, cancer cell growth and malignant phenotypes were analyzed. Results: The obtained transfectants that could express antisense hTRT gene stably showed marked decrease in telomerase activity; the shortening of telomere was obvious; cells presented contact growth inhibition; in nude mice transplantation, the rate of tumor induction dramatically decreased. Conclusion: Antisense hTRT gene expression can significantly inhibit telomerase activity of cancer cells and decrease malignant phenotypes in vitro and in vivo. Therefore, as a telomerase inhibitor, antisense hTRT gene may be a new pathway for cancer therapy.

  10. Efficient inhibition of human telomerase activity by antisense oligonucleotides sensitizes cancer cells to radiotherapy

    Institute of Scientific and Technical Information of China (English)

    Xue-mei JI; Cong-hua XIE; Ming-hao FANG; Fu-xiang ZHOU; Wen-jie ZHANG; Ming-sheng ZHANG; Yun-feng ZHOU

    2006-01-01

    Aim: To investigate the effect of the antisense oligonucleotides (ASODN) specific for human telomerase RNA (hTR) on radio sensitization and proliferation inhibition in human neurogliocytoma cells (U251). Methods: U251 cells were transfected with hTR ASODN or nonspecific oligonucleotides (NSODN). Before and after irradiation of 60Co-γray, telomerase activity was assayed by telomeric repeat amplification protocol (TRAP-PCR-ELISA), and DNA damage and repair were examined by the comet assay. The classical colony assay was used to plot the cell-survival curve, to detect the D0 value. Results: hTR antisense oligonucleotides could downregulate the telomerase activity, increase radiation induced DNA damage and reduce the subsequent repair. Furthermore, it could inhibit the proliferation and decrease the D0 value which demonstrates rising radiosensitivity. However, telomere length was unchanged over a short period of time. Conclusion: These findings suggest that an ASODN-based strategy may be used to develop telomerase inhibitors, which can efficiently sensitize radiotherapy.

  11. Physical Connectivity Mapping by Circular Permutation of Human Telomerase RNA Reveals New Regions Critical for Activity and Processivity.

    Science.gov (United States)

    Mefford, Melissa A; Zappulla, David C

    2015-01-01

    Telomerase is a specialized ribonucleoprotein complex that extends the 3' ends of chromosomes to counteract telomere shortening. However, increased telomerase activity is associated with ∼90% of human cancers. The telomerase enzyme minimally requires an RNA (hTR) and a specialized reverse transcriptase protein (TERT) for activity in vitro. Understanding the structure-function relationships within hTR has important implications for human disease. For the first time, we have tested the physical-connectivity requirements in the 451-nucleotide hTR RNA using circular permutations, which reposition the 5' and 3' ends. Our extensive in vitro analysis identified three classes of hTR circular permutants with altered function. First, circularly permuting 3' of the template causes specific defects in repeat-addition processivity, revealing that the template recognition element found in ciliates is conserved in human telomerase RNA. Second, seven circular permutations residing within the catalytically important core and CR4/5 domains completely abolish telomerase activity, unveiling mechanistically critical portions of these domains. Third, several circular permutations between the core and CR4/5 significantly increase telomerase activity. Our extensive circular permutation results provide insights into the architecture and coordination of human telomerase RNA and highlight where the RNA could be targeted for the development of antiaging and anticancer therapeutics. PMID:26503788

  12. Clinical Significance of Telomerase Activity and Human Telomerase Reverse Transcriptase mRNA Expression for Differential Diagnosis of Malignant and Benign Liver Lesions

    Institute of Scientific and Technical Information of China (English)

    RuifangFan; WeifengWong; XinxinBu; XianlingGuo; FengqiJia; ZhengyouLi; MengchaoWu; LixinWei

    2004-01-01

    OBJECTIVE To study the clinical significance of telomerase activity and human telomerase reverse transcriptase (hTERT) mRNA expression for differential diagnosis of malignant and benign liver lesions.METHODS Telomerase activity was determined by an ELISA-based telomeric repeat amplification protocol (EUSA-TRAP) assay on 130 surgical resected liver samples and 58 percutaneous biopsied liver samples. In addition, the samples were assayed for expression of hTERT mRNA measured by a. reverse transcriptase-polymerase chain reaction (RT-PCR). Postoperative pathological examinations were also performed on these samples.RESULTS Among the 130 surgical liver samples, the positive rates of telomerase activity in hepatocettutar carcinoma (HCC), liver cirrhosis and chronic hepatitis tissues were 85.9% (55/64), 25.0% (8/32) and 8.3% (2/24) respectively, and the positive rates of hTERT mRNA expression were 89.1% (57/64), 25.0% (8/32) and 8.3% (2/24) respectively, Neither telomerase activity nor hTERT mRNA expression was detected in 10 normal liver tissues.Among the 58 biopsied liver specimens, the positive rates of telomerase activity in HCC, cholangiocellular carcinoma, focal nodular hyperplasia, inflammatory pseudotumor and adenomatous hyperplasia tissues were 85.7% (30/35), 100% (4/4), 33.3% (4/12), 25.0% (1/4) and 33.3% (1/3) respectively, and the positive rates of hTERT mRNA expression were 88.6% (31/35), 100% (4/4), 33.3% (4/12), 25.0% (1/4) and 33.3% (1/3) respectively. The positive level of telomerase activity and hTERT mRNA expression in malignant fiver tumors was sign(ficantly higher than that found in benign liver lesions (P<0.01 ).CONCLUSION Determination of telomerase activity or hTERT mRNA expression in percutaneous biopsied liver tissues may be useful for differential diagnosis in malignant and benign liver lesions.

  13. Telomerase expression extends the proliferative life-span and maintains the osteogenic potential of human bone marrow stromal cells

    DEFF Research Database (Denmark)

    Simonsen, Janne Lytoft; Kjeldsen, Cecilia Rosada; Serakinci, Nedime;

    2002-01-01

    Human bone marrow stromal cells (hMSCs) were stably transduced by a retroviral vector containing the gene for the catalytic subunit of human telomerase (hTERT). Transduced cells (hMSC-TERTs) had telomerase activity, and the mean telomere length was increased as compared with that of control cells...... subculturing, did not form tumors, and had a normal karyotype. When implanted subcutaneously in immunodeficient mice, the transduced cells formed more bone than did normal cells. These results suggest that ectopic expression of telomerase in hMSCs prevents senescence-associated impairment of osteoblast...

  14. Telomerase extends the lifespan of virus-transformed human cells without net telomere lengthening

    OpenAIRE

    Zhu, Jiyue; Wang, He; Bishop, J. Michael; Elizabeth H. Blackburn

    1999-01-01

    Human fibroblasts whose lifespan in culture has been extended by expression of a viral oncogene eventually undergo a growth crisis marked by failure to proliferate. It has been proposed that telomere shortening in these cells is the property that limits their proliferation. Here we report that ectopic expression of the wild-type reverse transcriptase protein (hTERT) of human telomerase averts crisis, at the same time reducing the frequency of dicentric and abnormal chromosomes. Surprisingly, ...

  15. The effect of β-ionone on telomerase activity in the human leukemia cell line K562

    Directory of Open Access Journals (Sweden)

    Zohreh Faezizadeh

    2015-06-01

    Full Text Available Background: Telomerase is highly activated in most human cancer cells, therefore, its inhibition has been proposed as a novel and promising strategy for cancer therapy. Many plant-derived anticancer agents act through inhibition of telomerase activity and induction of apoptosis. β-ionone, a carotenoid compound isolated from Roseaceae, has been reported to possess anticancer properties. The present study was undertaken to examine the mechanism of β-ionone-induced apoptosis in human leukemia cell line K562 with special emphasis on its role in telomerase inhibition. Method: In this study the anti-proliferation effect of β-ionone on K562 cells was evaluated by MTT assay. Apoptosis rate was detected by Hoechst staining and flow cytometry analysis. Telomerase activity was measured by (TRAP ELISA assay. Results: Exposure of K562 cells to β-ionone caused a dose-dependent decrease in proliferation. Flow cytometry analysis and Hoechst staining showed that percentage of apoptotic cells markedly increased with an increase in β-ionone concentration. Compared to control cells, treatment of K562 cells with β-ionone resulted in a significant decrease of telomerase activity. Moreover, a positive correlation was detected between telomerase inhibition and apoptosis induction in the treated K562 cells. Conclusion: Based on these results, β-ionone is an appropriate candidate for inhibiting telomerase activity in K562 cells. Therefore, it may be utilized as a novel drug against some leukemia cell lines.

  16. Therapeutic Targeting of Telomerase

    OpenAIRE

    Kathrin Jäger; Michael Walter

    2016-01-01

    Telomere length and cell function can be preserved by the human reverse transcriptase telomerase (hTERT), which synthesizes the new telomeric DNA from a RNA template, but is normally restricted to cells needing a high proliferative capacity, such as stem cells. Consequently, telomerase-based therapies to elongate short telomeres are developed, some of which have successfully reached the stage I in clinical trials. Telomerase is also permissive for tumorigenesis and 90% of all malignant tumors...

  17. Maintenance of differentiation potential of human bone marrow mesenchymal stem cells immortalized by human telomerase reverse transcriptase gene despite [corrected] extensive proliferation

    DEFF Research Database (Denmark)

    Abdallah, Basem M; Haack-Sørensen, Mandana; Burns, Jorge S;

    2005-01-01

    that overexpression of human telomerase reverse transcriptase (hTERT) in hMSC reconstitutes telomerase activity and extends life span of the cells [Nat. Biotechnol. 20 (2002) 592]. In the present study, we have performed extensive characterization of three independent cell lines derived from the...

  18. EFFECT OF SeO2 ON TELOMERASE ACTIVITY IN HUMAN LUNG CARCINOMA CELL LINE GLC-82

    Institute of Scientific and Technical Information of China (English)

    陈维香; 曹晓哲; 朱任之

    2003-01-01

    Objective: To observe the effect of inhibition of telomerase activity by selenium dioxide (SeO2) on lung carcinoma cell line GLC-82. Methods: TRAP-PCR-ELISA was used to study the changes of telomerase activity in human pulmonary adenocarcinoma cell line GLC-82 treated by SeO2 at the different concentrations (3, 10, 30 μmol/L) and for different times (24, 48, and 72 h). Results: SeO2 inhibited the telomerase activity of GLC-82 at the different concentrations after treatment of 24, 48 and 72 h. Conclusion: SeO2 inhibits from telomerase activity of human lung carcinoma line GLC-82. The effect of inhibition is dose-dependant and time-dependant.

  19. Dynamics of Telomeres and Promyelocytic Leukemia Nuclear Bodies in a Telomerase-negative Human Cell Line

    OpenAIRE

    Jegou, Thibaud; Chung, Inn; Heuvelman, Gerrit; Wachsmuth, Malte; Görisch, Sabine M.; Greulich-Bode, Karin M.; Boukamp, Petra; Lichter, Peter; Rippe, Karsten

    2009-01-01

    Telomerase-negative tumor cells maintain their telomeres via an alternative lengthening of telomeres (ALT) mechanism. This process involves the association of telomeres with promyelocytic leukemia nuclear bodies (PML-NBs). Here, the mobility of both telomeres and PML-NBs as well as their interactions were studied in human U2OS osteosarcoma cells, in which the ALT pathway is active. A U2OS cell line was constructed that had lac operator repeats stably integrated adjacent to the telomeres of ch...

  20. Inhibition of Proliferation and Induction of Apoptosis in Human Renal Carcinoma Cells by Anti-telomerase Small Interfering RNAs

    Institute of Scientific and Technical Information of China (English)

    Jun-Nian ZHENG; Teng-Xiang MA; Ya-Feng SUN; Dong-Sheng PEI; Jun-Jie LIU; Jia-Cun CHEN; Wang LI; Xiao-Qing SUN; Qi-Duo SHI; Rui-Fa HAN

    2006-01-01

    Telomerase is an attractive molecular target for cancer therapy because it is present in most malignant cells but is undetectable in most normal somatic cells. Human telomerase consists of two subunits,an RNA component (hTR) and a human telomerase reverse transcriptase component (hTERT). Small interfering RNA (siRNA), one kind of RNA interferences, has been demonstrated to be an effective method to inhibit target gene expression in human cells. We investigated the effects of siRNA targeting at both hTR and hTERT mRNA on the inhibition of telomerase activity in human renal carcinoma cells (HRCCs). The proliferation and apoptosis of HRCCs were examined. The treatment of HRCCs using hTR and hTERT siRNAs resulted in significant decrease of hTR mRNA, hTERT mRNA and hTERT protein. The siRNA can also inhibit the telomerase activity and the proliferation of HRCCs. Moreover, they can induce apoptotic cell death in a dose-dependent manner. From these findings, we propose that the inhibition of telomerase activity using siRNA targeting hTR and hTERT might be a rational approach in renal cancer therapy.

  1. Telomerase-specific oncolytic virotherapy for human hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    AIM: To evaluate the therapeutic efficiency of replicative adenovirus CNHK300 targeted in telomerase-positive hepatocellular carcinoma. METHODS: CNHK300, ONYX-015 (55 kDa protein deleted adenovirus) and wtAd5 (wild type adenovirus 5) were compared, and virus proliferation assay, cell viability assay, Western blot and fluorescence microscopy were used to evaluate the proliferation and cytolysis selectivity of CNHK300.RESULTS:The replicative multiples in Hep3B and HepG after 48 h of CNHK300 proliferation were 40625and 65326 fold, respectively, similar to that of wtAd5..However, CNHK300 exhibited attenuated replicative ability in normal fibroblast cell line BJ.CNHK300 could lyse hepatocellular carcinoma cells at a low multiplicity of infection (MOI),but could not affect growth of normal cells even at a high MOI.CONCLUSION:CNHK300 is a cancer-selective replication-competent adenovirus which can cause oncolysis of liver cancer cells as well as wtAd5 (wild type adenovirus 5),but had severely attenuated replicative and cytolytic ability in normal cells. This novel strategy of cancer treatment offers a promising treatment platform.

  2. Combination of telomerase antisense oligonucleotides simultaneously targeting hTR and hTERT produces synergism of inhibition of telomerase activity and growth in human colon cancer cell line

    Institute of Scientific and Technical Information of China (English)

    Xiao-Hua Fu; Jian-Song Zhang; Na Zhang; Yang-De Zhang

    2005-01-01

    AIM: To investigate synergism of inhibition of telomerase activity and proliferation of human colon cancer cells by combination of telomerase antisense oligonucleotides (ASODNs) simultaneously targeting human telomerase RNA (hTR) and human telomerase reverse transcriptase (hTERT)in vitro.METHODS: ASODN of hTR and ASODN of hTERT were transfected into human colon cancer SW480 cells by liposomal transfection reagents. Telomerase activity of SW480 cells was examined using telomeric repeat amplification protocol (TRAP)-enzyme-linked immunosorbent assay (PCR-ELISA). Proliferation activity of SW480 cells was tested by methyl thiazolyl tetrazolium assay. Apoptosis and cell cycle were analyzed by flow cytometry.RESULTS: The telomerase activity and cell survival rate in SW480 cells transfected with 0.2 μmol/L of ASODN of hTR or ASODN of hTERT for 24-72 h were significantly decreased in a time-dependent manner compared with those after treatment with sense oligonucleotides and untreated (telomerase activity: 24 h, 73%, 74% vs 99%,98%; 48 h, 61%, 55% vs 98%, 99%; 72 h, 41%, 37% vs 99%, 97%; P<0.01; cell survival rate: 24 h, 88%, 86%vs94%, 98%; 48 h, 49%, 47% vs94%, 97%; 72 h, 44%,42% vs 92%, 96%; P<0.01). Moreover, the telomerase activity and the cell survival rate in SW480 cells treated by the combination of telomerase anti-hTR and anti-hTERT were more significantly suppressed than single anti-hTR or anti-hTERT (telomerase activity: 24 h, 59% vs 73%,74%; 48 h, 43% vs61%, 55%; 72 h, 18% vs41%, 37%;P<0.01; cell survival rate: 24 h, 64% vs88%, 86%; 48 h,37% vs49%, 47%; 72 h, 25% vs44%, 42%; P<0.01).Meanwhile, the apoptosis rates in the combination group were markedly increased compared with those in the single group (24 h, 18.0% vs 7.2%, 7.4%; 48 h, 23.0%vs 13.0%, 14.0%; 72 h, 28.6% vs13.2%, 13.75; P<0.01).Cells in combination group were arrested at G0/G1 phase.CONCLUSION: Telomerase anti-hRT and anti-hTERT suppress telomerase activity, and inhibit growth of human

  3. Critical Role for Telomerase in the Mechanism of Flow-Mediated Dilation in the Human Microcirculation

    Science.gov (United States)

    Freed, Julie K.; Durand, Matthew J.; Riedel, Michael; Ait-Aissa, Karima; Green, Paula; Hockenberry, Joseph C.; Morgan, R. Garret; Donato, Anthony J.; Peleg, Refael; Gasparri, Mario; Rokkas, Chris K.; Santos, Janine H.; Priel, Esther; Gutterman, David D.

    2016-01-01

    Rationale: Telomerase is a nuclear regulator of telomere elongation with recent reports suggesting a role in regulation of mitochondrial reactive oxygen species. Flow-mediated dilation in patients with cardiovascular disease is dependent on the formation of reactive oxygen species. Objective: We examined the hypothesis that telomerase activity modulates microvascular flow-mediated dilation, and loss of telomerase activity contributes to the change of mediator from nitric oxide to mitochondrial hydrogen peroxide in patients with coronary artery disease (CAD). Methods and Results: Human coronary and adipose arterioles were isolated for videomicroscopy. Flow-mediated dilation was measured in vessels pretreated with the telomerase inhibitor BIBR-1532 or vehicle. Statistical differences between groups were determined using a 2-way analysis of variance repeated measure (n≥4; P<0.05). L-NAME (Nω-nitro-L-arginine methyl ester; nitric oxide synthase inhibitor) abolished flow-mediated dilation in arterioles from subjects without CAD, whereas polyethylene glycol-catalase (PEG-catalase; hydrogen peroxide scavenger) had no effect. After exposure to BIBR-1532, arterioles from non-CAD subjects maintained the magnitude of dilation but changed the mediator from nitric oxide to mitochondrial hydrogen peroxide (% max diameter at 100 cm H2O: vehicle 74.6±4.1, L-NAME 37.0±2.0*, PEG-catalase 82.1±2.8; BIBR-1532 69.9±4.0, L-NAME 84.7±2.2, PEG-catalase 36.5±6.9*). Conversely, treatment of microvessels from CAD patients with the telomerase activator AGS 499 converted the PEG-catalase-inhibitable dilation to one mediated by nitric oxide (% max diameter at 100 cm H2O: adipose, AGS 499 78.5±3.9; L-NAME 10.9±17.5*; PEG-catalase 79.2±4.9). Endothelial-independent dilation was not altered with either treatment. Conclusions: We have identified a novel role for telomerase in re-establishing a physiological mechanism of vasodilation in arterioles from subjects with CAD. These findings

  4. Antitumor effects of specific telomerase inhibitor GRN163 in human glioblastoma xenografts1

    Science.gov (United States)

    Ozawa, Tomoko; Gryaznov, Sergei M.; Hu, Lily J.; Pongracz, Krisztina; Santos, Raquel A.; Bollen, Andrew W.; Lamborn, Kathleen R.; Deen, Dennis F.

    2004-01-01

    Telomerase is a ribonucleoprotein complex that elongates telomeric DNA and appears to play an important role in cellular immortalization of cancers. Because telomerase is expressed in the vast majority of malignant gliomas but not in normal brain tissues, it is a logical target for glioma-specific therapy. The telomerase inhibitor GRN163, a 13-mer oligonucleotide N3′→P5′ thio-phosphoramidate (Geron Corporation, Menlo Park, Calif.), is complementary to the template region of the human telomerase RNA subunit hTR. When athymic mice bearing U-251 MG human brain tumor xenografts in their flanks were treated intratumorally with GRN163, a significant growth delay in tumor size was observed (P < 0.01 in all groups) as compared to the tumor size in mice receiving a mismatched oligonucleotide or the carrier alone. We also investigated biodistribution of the drug in vivo in an intracerebral rat brain-tumor model. Fluorescein-labeled GRN163 was loaded into an osmotic minipump and infused directly into U-251 MG brain tumors over 7 days. Examination of the brains revealed that GRN163 was present in tumor cells at all time points studied. When GRN163 was infused into intracerebral U-251 MG tumors shortly after their implantation, it prevented their establishment and growth. Lastly, when rats with larger intracerebral tumors were treated with the inhibitor, GRN163 increased animal survival times. Our results demonstrate that the antitelomerase agent GRN163 inhibits growth of glioblastoma in vivo, exhibits favorable intracerebral tumor uptake properties, and prevents the growth of intracerebral tumors. These findings support further development of this compound as a potential anticancer agent. PMID:15279714

  5. Inhibitory effect of human telomerase antisense oligodeoxyribonucleotides on the growth of gastric cancer cell lines in variant tumor pathological subtype

    Institute of Scientific and Technical Information of China (English)

    Jing Ye; Yun-Lin Wu; Shu Zhang; Zi Chen; Li-Xia Guo; Ruo-Yu Zhou; Hong Xie

    2005-01-01

    AIM: To investigate the inhibitory effect of specialized human telomerase antisense oligodeoxyribonucleotides on the growth of well (MKN-28), moderately (SGC-7901)and poorly (MKN-45) differentiated gastric cancer cell lines under specific conditions and its inhibition mechanism,and to observe the correlation between the growth inhibition ratio and the tumor pathologic subtype of gastric cancer cells.METHODS: Telomerase activity in three gastric cancer cell lines of variant tumor pathologic subtype was determined by modified TRAP assay before and after the specialized human telomerase antisense oligodeoxyribonucleotides were dealt with under specific conditions. Effect of antisense oligomer under specific conditions of the growth and viability of gastric cancer cell lines was explored by using trypan blue dye exclusion assay, and cell apoptosis was detected by cell morphology observation, flow cytometry and TUNEL assay.RESULTS: Telomerase activity was detected in well,moderately and poorly differentiated gastric cancer cell lines (the quantification expression of telomerase activity was 43.7TPG, 56.5TPG, 76.7TPG, respectively).Telomerase activity was controlled to 30.2TPG, 36.3TPG and 35.2TPG for MKN-28, SGC-7901 and MKN-45 cell lines respectively after treatment with human telomerase antisense oligomers at the concentration of 5 μmol/L, and was entirely inhibited at 10 μmol/L, against the template region of telomerase RNA component, whereas no inhibition effect was detected in missense oligomers (P<0.05). After treatment with antisense oligomers at different concentrations under specific conditions for 96 h, significant growth inhibition effects were found in MKN-45 and SGC-7901gastric cancer cell lines (the inhibition ratio was 40.89%and 71.28%), but not in MKN-28 cell lines (15.86%). The ratio of inactive SGC-7901 cells increased according to the prolongation of treatment from 48 to 96 h. Missense oligomers could not lead to the same effect (P<0

  6. Non-invasive imaging of human telomerase activity-targeting enzyme in BNCT

    Energy Technology Data Exchange (ETDEWEB)

    Tujino, H.; Imahori, Y.; Mineura, K. [Kyoto Prefectural Univ. of Medicine, Dept. of Neurosurgery, Kyoto (Japan); Ono, K. [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst; Fujii, R. [Nishijin Hospital, Kyoto (Japan); Ueda, S. [Maizuru National Hospital, Kyoto (Japan)

    2000-10-01

    In the present study, we achieved non-invasive imaging of gene expression of human telomerase (hTRT) in brain tumors by systemic administration of antisense peptide nucleic acid (PNA) and phosphorothioate-derivative (S-oligomer) labeled with {sup 11}C as a positron emitter. The difference in the rate of incorporation of antisense between the tumor and the surrounding normal brain tissue is large enough to apply this technique practically to non-invasive imaging of gene expression in humans using positron emission tomography (PET). We also expected that this technique can be used in developing the peculiar boron carrier in the neutron capture therapy. (author)

  7. Non-invasive imaging of human telomerase activity-targeting enzyme in BNCT

    International Nuclear Information System (INIS)

    In the present study, we achieved non-invasive imaging of gene expression of human telomerase (hTRT) in brain tumors by systemic administration of antisense peptide nucleic acid (PNA) and phosphorothioate-derivative (S-oligomer) labeled with 11C as a positron emitter. The difference in the rate of incorporation of antisense between the tumor and the surrounding normal brain tissue is large enough to apply this technique practically to non-invasive imaging of gene expression in humans using positron emission tomography (PET). We also expected that this technique can be used in developing the peculiar boron carrier in the neutron capture therapy. (author)

  8. Therapeutic Targeting of Telomerase.

    Science.gov (United States)

    Jäger, Kathrin; Walter, Michael

    2016-01-01

    Telomere length and cell function can be preserved by the human reverse transcriptase telomerase (hTERT), which synthesizes the new telomeric DNA from a RNA template, but is normally restricted to cells needing a high proliferative capacity, such as stem cells. Consequently, telomerase-based therapies to elongate short telomeres are developed, some of which have successfully reached the stage I in clinical trials. Telomerase is also permissive for tumorigenesis and 90% of all malignant tumors use telomerase to obtain immortality. Thus, reversal of telomerase upregulation in tumor cells is a potential strategy to treat cancer. Natural and small-molecule telomerase inhibitors, immunotherapeutic approaches, oligonucleotide inhibitors, and telomerase-directed gene therapy are useful treatment strategies. Telomerase is more widely expressed than any other tumor marker. The low expression in normal tissues, together with the longer telomeres in normal stem cells versus cancer cells, provides some degree of specificity with low risk of toxicity. However, long term telomerase inhibition may elicit negative effects in highly-proliferative cells which need telomerase for survival, and it may interfere with telomere-independent physiological functions. Moreover, only a few hTERT molecules are required to overcome senescence in cancer cells, and telomerase inhibition requires proliferating cells over a sufficient number of population doublings to induce tumor suppressive senescence. These limitations may explain the moderate success rates in many clinical studies. Despite extensive studies, only one vaccine and one telomerase antagonist are routinely used in clinical work. For complete eradication of all subpopulations of cancer cells a simultaneous targeting of several mechanisms will likely be needed. Possible technical improvements have been proposed including the development of more specific inhibitors, methods to increase the efficacy of vaccination methods, and

  9. Therapeutic Targeting of Telomerase

    Science.gov (United States)

    Jäger, Kathrin; Walter, Michael

    2016-01-01

    Telomere length and cell function can be preserved by the human reverse transcriptase telomerase (hTERT), which synthesizes the new telomeric DNA from a RNA template, but is normally restricted to cells needing a high proliferative capacity, such as stem cells. Consequently, telomerase-based therapies to elongate short telomeres are developed, some of which have successfully reached the stage I in clinical trials. Telomerase is also permissive for tumorigenesis and 90% of all malignant tumors use telomerase to obtain immortality. Thus, reversal of telomerase upregulation in tumor cells is a potential strategy to treat cancer. Natural and small-molecule telomerase inhibitors, immunotherapeutic approaches, oligonucleotide inhibitors, and telomerase-directed gene therapy are useful treatment strategies. Telomerase is more widely expressed than any other tumor marker. The low expression in normal tissues, together with the longer telomeres in normal stem cells versus cancer cells, provides some degree of specificity with low risk of toxicity. However, long term telomerase inhibition may elicit negative effects in highly-proliferative cells which need telomerase for survival, and it may interfere with telomere-independent physiological functions. Moreover, only a few hTERT molecules are required to overcome senescence in cancer cells, and telomerase inhibition requires proliferating cells over a sufficient number of population doublings to induce tumor suppressive senescence. These limitations may explain the moderate success rates in many clinical studies. Despite extensive studies, only one vaccine and one telomerase antagonist are routinely used in clinical work. For complete eradication of all subpopulations of cancer cells a simultaneous targeting of several mechanisms will likely be needed. Possible technical improvements have been proposed including the development of more specific inhibitors, methods to increase the efficacy of vaccination methods, and

  10. Therapeutic Targeting of Telomerase

    Directory of Open Access Journals (Sweden)

    Kathrin Jäger

    2016-07-01

    Full Text Available Telomere length and cell function can be preserved by the human reverse transcriptase telomerase (hTERT, which synthesizes the new telomeric DNA from a RNA template, but is normally restricted to cells needing a high proliferative capacity, such as stem cells. Consequently, telomerase-based therapies to elongate short telomeres are developed, some of which have successfully reached the stage I in clinical trials. Telomerase is also permissive for tumorigenesis and 90% of all malignant tumors use telomerase to obtain immortality. Thus, reversal of telomerase upregulation in tumor cells is a potential strategy to treat cancer. Natural and small-molecule telomerase inhibitors, immunotherapeutic approaches, oligonucleotide inhibitors, and telomerase-directed gene therapy are useful treatment strategies. Telomerase is more widely expressed than any other tumor marker. The low expression in normal tissues, together with the longer telomeres in normal stem cells versus cancer cells, provides some degree of specificity with low risk of toxicity. However, long term telomerase inhibition may elicit negative effects in highly-proliferative cells which need telomerase for survival, and it may interfere with telomere-independent physiological functions. Moreover, only a few hTERT molecules are required to overcome senescence in cancer cells, and telomerase inhibition requires proliferating cells over a sufficient number of population doublings to induce tumor suppressive senescence. These limitations may explain the moderate success rates in many clinical studies. Despite extensive studies, only one vaccine and one telomerase antagonist are routinely used in clinical work. For complete eradication of all subpopulations of cancer cells a simultaneous targeting of several mechanisms will likely be needed. Possible technical improvements have been proposed including the development of more specific inhibitors, methods to increase the efficacy of vaccination

  11. The Effect of Nano-apatite on the Expression of Telomerase Gene of Human Hepatocellular Carcinoma Cells

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    To investigate the effect of nano- apatite on the expression of the telomerase gene of human hepatocellular carcinoma cell lines and further explore the mechanism of the nano-apatite inhibiting cancer cells. Using the hybridization in situ method to detect the expression of the telomerase gene of human hepatocellular carcinoma cells treated with the nano- apatite for 4 h at 37 ℃. The hybridization in situ showed that the cytoplasm of the positive cells was stained in nigger-brown. The positive cell rate of the control group was 88.49% , the cisplatin group was 25.6% , the nano-apatite group was 63.6% . The activity oftelomerase gene was both obviously declined comparing with the control group and the difference had significance (p < 0.05, p < 0.01 ). The nanoapatite obviously inhabit the expression of the telomerase gene of human hepatocellular carcinoma cells.

  12. Antiproliferative effect of rapamycin on human T-cell leukemia cell line Jurkat by cell cycle arrest and telomerase inhibition

    Institute of Scientific and Technical Information of China (English)

    Yan-min ZHAO; Qian ZHOU; Yun XU; Xiao-yu LAI; He HUANG

    2008-01-01

    Aim:To examine the ability of rapamycin to suppress growth and regulate telomerase activity in the human T-cell leukemia cell line Jurkat. Methods:Cell proliferation was assessed after exposure to rapamycin by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell cycle progression and apoptosis were determined by flow cytometry. The proteins important for cell cycle progres-sion and Akt/mammalian target of rapamycin signaling cascade were assessed by Western blotting. Telomerase activity was quantified by telomeric repeat amplication protocol assay. The human telomerase reverse transcriptase (hTERT) mRNA levels were determined by semi-quantitative RT-PCR. Results:Rapamycin inhibited the proliferation of Jurkat, induced G1 phase arrest, unregulated the pro-tein level of p21 as well as p27, and downregulated cyclinD3, phospho-p70s6k, and phospho-s6, but had no effect on apoptosis. Treatment with rapamycin reduced telomerase activity, and reduced hTERT mRNA and protein expression. Conclusion:Rapamycin displayed a potent antileukemic effect in the human T-cell leukemia cell line by inhibition of cell proliferation through G1 cell cycle arrest and also through the suppression of telomerase activity, suggesting that rapamycin may have potential clinical implications in the treatment of some leukemias.

  13. 肿瘤组织端粒酶活性的检测及临床意义%Detection of Telomerase Activity in Human Tumor

    Institute of Scientific and Technical Information of China (English)

    姜淑芳; 魏玲

    2003-01-01

    Objective To detect telomerase activity in human cancer. Methods 74 tumor samples and 61 tumoradjacent tissue, which were confirmedl by pathology, were examined by Telomeric repeat amplification protocol (TRAP) assay.Results 60 out of 74 (81.1%) tumor sacple exhibited telomerase activity. However, telomerase activity in the tumoradjacent tissue could be detected only in 7 out of 61 (11.5%) specimens (X2 = 64.8,P< 0.005)o Conlcusion Telomerase may be a good diagnostic biomarker for tumor detection.

  14. Clinical significance of detection of human telomerase reverse transcriptase in colorectal cancer and its precancerous lesions

    Institute of Scientific and Technical Information of China (English)

    刘少平

    2014-01-01

    Objective To evaluate the expression and clinical significance of human telomerase reverse transcriptase(h TERT)in colorectal cancer and its precancerous lesion.Methods The levels of h TERT expression were detected by immunohistochemistry in colorectal cancers(n=95),colorectal adenomatous polyposis(n=30)and normal colorectal tissues(n=30).The relationship between the expression of h TERT in colorectal cancer tissues and the pathologic features and prognosis were analyzed.Results The positive rate of h TERT expression

  15. Cryptolepine Derivatives:Quadruplex-Interactive Agents as Inhibitors of Human Telomerase

    Institute of Scientific and Technical Information of China (English)

    HUANG,Zhi-Shu; ZHOU,Jin-Lin; LU,Yu-Jing; GU,Lian-Quan

    2004-01-01

    @@ Alkaloids are very important natural products. Most of them have biologic activity. Many novel drugs have been developed based on alkaloids, such as camptothecin, taxol, vinblastine. A series of novel cryptolepine derivatives were synthesized (Figure 1). The interaction of cryptolepine derivatives with G-quadruplex (Figure 2) was studied by CD and UV spectra.[1] Most of these compounds can induce the formation of G-quadruplex and stabilize the formed G-quadruplex, resulting in the inhibitory effect on telomerase. Most of these cryptolepine derivatives have potent cytotoxicity in vitro against human tumor cell line.

  16. Discovery of Ligands for a Novel Target, the Human Telomerase RNA, Based on Flexible-Target Virtual Screening and NMR

    OpenAIRE

    Pinto, Irene Gómez; Guilbert, Christophe; Ulyanov, Nikolai B.; Stearns, Jay; James, Thomas L.

    2008-01-01

    The human ribonucleoprotein telomerase is a validated anticancer drug target, and hTRP2b is a part of the human telomerase RNA (hTR) essential for its activity. Interesting ligands that bind hTR-P2b were identified by iteratively using a tandem structure-based approach: docking of potential ligands from small databases to hTR-P2b via the program MORDOR, which permits flexibility in both ligand and target, with subsequent NMR screening of high-ranking compounds. A high percentage of the compou...

  17. Establishment and characterization of buffalo fetal fibroblasts induced with human telomerase reverse transcriptase.

    Science.gov (United States)

    Zhang, Shun; Guan, Xiaomei; Lu, Fenghua; Jiang, Jianrong; Deng, Yanfei; Luo, Chan; Shi, Deshun

    2016-10-01

    Fetal fibroblasts are often used as donor cells for SCNT, but their short lifespan greatly limits this application. To provide stable and long-lifespan cells, buffalo fetal fibroblasts (BFFs) transfected with human telomerase reverse transcriptase (hTERT). The hTERT-transfected BFFs (hTERT-BFFs) were evaluated by qRT-PCR, Western blot, karyotype analysis, telomerase activity assay, growth curve assay, flow cytometry, and soft agar assay. The development of SCNT embryos derived from hTERT-BFFs was also assessed in vitro. The morphology of hTERT-BFFs was similar to the nontransfected BFFs, and the karyotype of hTERT-BFFs was normal at passage 30. The hTERT-BFFs at passage 4 and 30 had higher telomerase activity and extended proliferative lifespan with an increase in cell population at S phase when compared with nontransfected BFFs at passage 5 and 30. The mRNA expression of p53 in hTERT-BFFs at passage 5 and 30 remained unchanged when compared with nontransfected BFFs at passage 5, whereas the mRNA expression of p53 in the nontransfected BFFs at passage 30 was increased. Soft agar assay showed that hTERT-BFFs at passage 30 were not a malignant phenotype. Significantly, more SCNT embryos derived from hTERT-BFFs at passage 5 and 30 developed to blastocysts in comparison with BFFs at passage 30. The Caudal type homeobox 2 and Connexin 43 genes were indicated to involve in the development of cloned embryos. These results indicate that transfection of BFFs with hTERT can extend their lifespan and retain their basic and key biological characteristics in the status of primary BFFs. PMID:27388808

  18. PCB153 reduces telomerase activity and telomere length in immortalized human skin keratinocytes (HaCaT) but not in human foreskin keratinocytes (NFK)

    Energy Technology Data Exchange (ETDEWEB)

    Senthilkumar, P.K. [Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA (United States); Robertson, L.W. [Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA (United States); Department of Occupational and Environmental Health, The University of Iowa, Iowa City, IA (United States); Ludewig, G., E-mail: Gabriele-ludewig@uiowa.edu [Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA (United States); Department of Occupational and Environmental Health, The University of Iowa, Iowa City, IA (United States)

    2012-02-15

    Polychlorinated biphenyls (PCBs), ubiquitous environmental pollutants, are characterized by long term-persistence in the environment, bioaccumulation, and biomagnification in the food chain. Exposure to PCBs may cause various diseases, affecting many cellular processes. Deregulation of the telomerase and the telomere complex leads to several biological disorders. We investigated the hypothesis that PCB153 modulates telomerase activity, telomeres and reactive oxygen species resulting in the deregulation of cell growth. Exponentially growing immortal human skin keratinocytes (HaCaT) and normal human foreskin keratinocytes (NFK) were incubated with PCB153 for 48 and 24 days, respectively, and telomerase activity, telomere length, superoxide level, cell growth, and cell cycle distribution were determined. In HaCaT cells exposure to PCB153 significantly reduced telomerase activity, telomere length, cell growth and increased intracellular superoxide levels from day 6 to day 48, suggesting that superoxide may be one of the factors regulating telomerase activity, telomere length and cell growth compared to untreated control cells. Results with NFK cells showed no shortening of telomere length but reduced cell growth and increased superoxide levels in PCB153-treated cells compared to untreated controls. As expected, basal levels of telomerase activity were almost undetectable, which made a quantitative comparison of treated and control groups impossible. The significant down regulation of telomerase activity and reduction of telomere length by PCB153 in HaCaT cells suggest that any cell type with significant telomerase activity, like stem cells, may be at risk of premature telomere shortening with potential adverse health effects for the affected organism. -- Highlights: ► Human immortal (HaCaT) and primary (NFK) keratinocytes were exposed to PCB153. ► PCB153 significantly reduced telomerase activity and telomere length in HaCaT. ► No effect on telomere length and

  19. PCB153 reduces telomerase activity and telomere length in immortalized human skin keratinocytes (HaCaT) but not in human foreskin keratinocytes (NFK)

    International Nuclear Information System (INIS)

    Polychlorinated biphenyls (PCBs), ubiquitous environmental pollutants, are characterized by long term-persistence in the environment, bioaccumulation, and biomagnification in the food chain. Exposure to PCBs may cause various diseases, affecting many cellular processes. Deregulation of the telomerase and the telomere complex leads to several biological disorders. We investigated the hypothesis that PCB153 modulates telomerase activity, telomeres and reactive oxygen species resulting in the deregulation of cell growth. Exponentially growing immortal human skin keratinocytes (HaCaT) and normal human foreskin keratinocytes (NFK) were incubated with PCB153 for 48 and 24 days, respectively, and telomerase activity, telomere length, superoxide level, cell growth, and cell cycle distribution were determined. In HaCaT cells exposure to PCB153 significantly reduced telomerase activity, telomere length, cell growth and increased intracellular superoxide levels from day 6 to day 48, suggesting that superoxide may be one of the factors regulating telomerase activity, telomere length and cell growth compared to untreated control cells. Results with NFK cells showed no shortening of telomere length but reduced cell growth and increased superoxide levels in PCB153-treated cells compared to untreated controls. As expected, basal levels of telomerase activity were almost undetectable, which made a quantitative comparison of treated and control groups impossible. The significant down regulation of telomerase activity and reduction of telomere length by PCB153 in HaCaT cells suggest that any cell type with significant telomerase activity, like stem cells, may be at risk of premature telomere shortening with potential adverse health effects for the affected organism. -- Highlights: ► Human immortal (HaCaT) and primary (NFK) keratinocytes were exposed to PCB153. ► PCB153 significantly reduced telomerase activity and telomere length in HaCaT. ► No effect on telomere length and

  20. Ectopic expression of telomerase enhances osteopontin and osteocalcin expression during osteogenic differentiation of human mesenchymal stem cells from elder donors

    Directory of Open Access Journals (Sweden)

    Machado CB

    2009-01-01

    Full Text Available Age related bone loss is one of the most prevalent diseases in the elder population. The osteoblasts are the effectors cells of bone formation and regeneration. With the aging the osteoblasts become senescent reducing their ability to produce bone. Cellular replicative senescence is triggered by telomers shortening. Telomerase elongate the telomers length and maintain the cell proliferative capacity. Here, we demonstrated that the expression of human telomerase reverse transcriptase mediated by an adenovirus vector increases the levels of osteopontin and osteocalcin mRNA during the in vitro osteogenic differentiation of elderly human mesenchymal stem cells. Bone marrow human mesenchymal stem cells were obtained from old donors (>65 years and induced to differentiate into osteoblasts for 14 days. The levels of mRNA of human telomerase reverse transcriptase, osteopontin and osteocalcin during the differentiation were assessed by semi-quantitative PCR before and during the differentiation on days 7 and 14. Infected cells showed 1.5 fold increase in telomerase expression. Also telomerized cells exhibit 1.5 fold increase in osteopontin and 0.5 fold increase in osteocalcin expression compared to primary osteoblasts isolated from the same donors. The transformed cells were not able to form tumours in NUDE mice.

  1. Establishment and characterization of a dairy goat mammary epithelial cell line with human telomerase (hT-MECs).

    Science.gov (United States)

    Shi, Huaiping; Shi, Hengbo; Luo, Jun; Wang, Wei; Haile, Abiel B; Xu, Huifen; Li, Jun

    2014-07-01

    Although research on dairy goat mammary gland have referred extensively to molecular mechanisms, research on lines of dairy goat mammary epithelial cells (MECs) are still rare. This paper sought to establish an immortal MEC line by stable transfection of human telomerase. MECs from a lactating (45 days post-parturition) Xinong Saanen dairy goat were cultured purely and subsequently transfected with a plasmid carrying the sequence of human telomerase. Immortalized MECs by human telomerase (hT-MECs) exhibited a typical cobblestone morphology and activity and expression levels of telomerase resembled that of MCF-7 cells. hT-MECs on passage 42 grew vigorously and 'S' sigmoid curves of growth were observed. Moreover, hT-MECs maintained a normal chromosome modal number of 2n=60, keratin 8 and epithelial membrane antigen (EMA) were evidently expressed, and beta-casein protein was synthesized and secreted. Beta-casein expression was enhanced by prolactin (Pmodel cell line, for molecular and functional analysis, of dairy goat MECs for an extended period of time. PMID:24889218

  2. Relationship between Dyskerin Expression and Telomerase Activity in Human Breast Cancer

    OpenAIRE

    Montanaro, Lorenzo; Calienni, Maria; Ceccarelli, Claudio; Santini, Donatella; Taffurelli, Mario; Pileri, Stefano; Treré, Davide; Derenzini, Massimo

    2008-01-01

    The nucleolar protein dyskerin is involved in the modification of specific uridine residues to pseudouridine on ribosomal and small nuclear RNAs and in the stabilization of the telomerase RNA component (TERC). In this study we investigated for the first time the relationship between dyskerin expression and telomerase activity in a series of 61 primary breast carcinomas. We found that when dyskerin mRNA values were very low the telomerase activity was markedly reduced, independently of the exp...

  3. Trend of telomerase activity change during human iPSC self-renewal and differentiation revealed by a quartz crystal microbalance based assay

    Science.gov (United States)

    Zhou, Yitian; Zhou, Ping; Xin, Yinqiang; Wang, Jie; Zhu, Zhiqiang; Hu, Ji; Wei, Shicheng; Ma, Hongwei

    2014-11-01

    Telomerase plays an important role in governing the life span of cells for its capacity to extend telomeres. As high activity of telomerase has been found in stem cells and cancer cells specifically, various methods have been developed for the evaluation of telomerase activity. To overcome the time-consuming procedures and complicated manipulations of existing methods, we developed a novel method named Telomeric Repeat Elongation Assay based on Quartz crystal microbalance (TREAQ) to monitor telomerase activity during the self-renewal and differentiation of human induced pluripotent stem cells (hiPSCs). TREAQ results indicated hiPSCs possess invariable telomerase activity for 11 passages on Matrigel and a steady decline of telomerase activity when differentiated for different periods, which is confirmed with existing golden standard method. The pluripotency of hiPSCs during differentiation could be estimated through monitoring telomerase activity and compared with the expression levels of markers of pluripotency gene via quantitative real time PCR. Regular assessment for factors associated with pluripotency or stemness was expensive and requires excessive sample consuming, thus TREAQ could be a promising alternative technology for routine monitoring of telomerase activity and estimate the pluripotency of stem cells.

  4. The effect of heavy ion 12C6+on the change of telomerase activity of the human hepatocellular cells and carcinoma cells

    Science.gov (United States)

    Dang, Bingrong

    The effect of heavy ion 12C6+on the change of telomerase activity of the human hepatocellular cells and carcinoma cells Dang Bingrong ,Hu Kaiqian (Institute of Modern Physics Chinese Academy of Sciences£¬Graduate University of Chinese Academy of Sciences lanzhou 730000) Abstract Objective To investigate the changes in telomerase and its activity in human tumor and normal cell after exposure of the cells to heavy ion radiation.Irradiation was performed at the Heavy Ion Researsh Facility in Lanzhou (HIRFL). Methods We use the hepatocellular cells HL-7702 and the hepatocellular carcinoma cells SMMC-7721 from the people to experiment. Cells were exposed to 12 C6+ irradiation at 0,1,2,3 and 4Gy. The hepatocellular cells HL-7702 exposed to 12 C6+ irradiation were re-cultured for 72 hours. The hepatocellular carcinoma cells SMMC-7721 were re-cultured for 24 hours and 72 hours. PCR based telomeric repeat amplification protocol(TRAP-PCR) method were used to determine the telomerase activity in SMMC-7721and HL-7702, respectively. Result HL-7702 cells didn't have telomerase. But the cells exposed to 2Gy and 3Gy have the telomerase activity, the cells exposed to 1Gy and 4Gy didn't have the telomerase activity. After exposure to heavy ionizing radiation 1-3Gy the telomerase activity in SMMC-7721 cells were significantly increased in a dose-and timedependent manner. The cells of 7721 exposed to 4Gy was significantly lower than that 0Gy cells. Conclusion Heavy ionizing radiation, as a high LET radiation,induces the increase in telomerase activity in low dose and the decrease in high dose. It indicates that telomerase participates in the repair process of DNA injury induced by heavy ionizing radiation. Key words telomerase heavy ion hepatocellular cells SMMC-7721 cells HL-7702 cells PCR- telomeric repeat amplification protocol

  5. The changes of telomerase activity of the human hepatocellular cells and carcinoma cells irradiated by 12C6+ ions

    International Nuclear Information System (INIS)

    In this paper, the changes of telomerase activity in human liver cells after exposed to the heavy ion radiation were investigated. Irradiation was performed at the Heavy Ion Research Facility in Lanzhou (HIRFL). The hepatocellular cells HL-7702 and the hepatocellular carcinoma cells SMMC-7721 used as model cell were exposed to 12C6+ irradiation at 0, 1, 2, 3 and 4Gy and formal irradiated cell was re-cultured for 72h and later irradiated cell was re-cultured for 24h and 72h respectively. PCR based on telomeric repeat amplification protocol (TRAP-PCR) method was used to determine the telomerase activity in SMMC-7721 and HL-7702, respectively. It has been found that the HL-7702 cells don't express the telomerase activity at 0Gy, 1Gy and 4Gy while the cells exposed to 2Gy and 3Gy express the telomerase activity clearly (p12C6+ in tumor therapy could kill tumor cells more efficiently than that by the other low LET rays. (authors)

  6. Inhibition of human telomerase reverse transcriptase in vivo and in vitro for retroviral vector-based antisense oligonucleotide therapy in ovarian cancer.

    Science.gov (United States)

    Qi, Z; Mi, R

    2016-01-01

    Human telomerase is absent in most normal tissues, but is abnormally activated in all major cancer cells. Telomerase enables tumor cells to maintain telomere length, allowing indefinite replicative capacity. Albeit not sufficient in itself to induce neoplasia, telomerase is believed to be necessary for cancer cells to grow without limit. Studies using an antisense oligonucleotide (ASODN) to the RNA component of telomerase or human telomerase reverse transcriptase (hTERT) demonstrate that telomerase in human tumor lines can be blocked in vivo. Inhibition of hTERT led to telomere shortening and cancer cell death, validating telomerase as a target for anticancer genetic therapy. Varieties of approaches for hTERT inhibition have been investigated. The aim of this study was to analyze the biological activity of ASODN to the hTERT mediated by retrovirus vector, which was used as therapy for ovarian tumor. We constructed and characterized a recombinant retrovirus vector with full-length hTERT antisense complementary DNA. The vector was introduced into ES-2 by lipofectamine-mediated gene transfection. The cellular proliferation and telomerase activity of the transformant cells were retarded. The hTERT gene expression and the telomerase activity of the transformant cells were both decreased. The transformant cells show partial reversion of the malignant phenotype. PT67 cells were also transfected with the recombinant vector and virus-producer cells were generated. The retrovirus-containing supernatant effectively inhibited the growth of human ovarian tumor xenografts in mouse models (subcutaneous tumor model), and enhanced the mouse survival time. PMID:26742579

  7. In vitro and ex vivo inhibition of human telomerase by anti-HIV nucleoside reverse transcriptase inhibitors (NRTIs but not by non-NRTIs.

    Directory of Open Access Journals (Sweden)

    Kyle R Hukezalie

    Full Text Available Telomerase is a specialized reverse transcriptase responsible for the de novo synthesis of telomeric DNA repeats. In addition to its established reverse transcriptase and terminal transferase activities, recent reports have revealed unexpected cellular activities of telomerase, including RNA-dependent RNA polymerization. This telomerase characteristic, distinct from other reverse transcriptases, indicates that clinically relevant reverse transcriptase inhibitors might have unexpected telomerase inhibition profiles. This is particularly important for the newer generation of RT inhibitors designed for anti-HIV therapy, which have reported higher safety margins than older agents. Using an in vitro primer extension assay, we tested the effects of clinically relevant HIV reverse transcriptase inhibitors on cellular telomerase activity. We observed that all commonly used nucleoside reverse transcriptase inhibitors (NRTIs, including zidovudine, stavudine, tenofovir, didanosine and abacavir, inhibit telomerase effectively in vitro. Truncated telomere synthesis was consistent with the expected mode of inhibition by all tested NRTIs. Through dose-response experiments, we established relative inhibitory potencies of NRTIs on in vitro telomerase activity as compared to the inhibitory potencies of the corresponding dideoxynucleotide triphosphates. In contrast to NRTIs, the non-nucleoside reverse transcriptase inhibitors (NNRTIs nevirapine and efavirenz did not inhibit the primer extension activity of telomerase, even at millimolar concentrations. Long-term, continuous treatment of human HT29 cells with select NRTIs resulted in an accelerated loss of telomere repeats. All tested NRTIs exhibited the same rank order of inhibitory potencies on telomerase and HIV RT, which, according to published data, were orders-of-magnitude more sensitive than other DNA polymerases, including the susceptible mitochondria-specific DNA polymerase gamma. We concluded that

  8. Using a non-radioisotopic, quantitative TRAP-based me thod detecting telomerase activities in human hepatoma cells

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A non-radioisotopic, quantitative TRAP-based telom erase activity assay was established mainly by using SYBR Green-I staining instead of radioisotope. Comparing with conventional radioisotope based method, it was better in reproducibility and accuracy. Using this method, we found telomerase activities were absent in normal human liver cells, while detected in all of four human hepatoma cell lines (BEL-7404, SMMC-7721, QGY-7903 and HCCM) without significant differences.

  9. The mouse telomerase RNA 5"-end lies just upstream of the telomerase template sequence.

    OpenAIRE

    Hinkley, C S; Blasco, M A; Funk, W D; Feng, J; Villeponteau, B; Greider, C W; Herr, W.

    1998-01-01

    Telomerase is a ribonucleoprotein enzyme with an essential RNA component. Embedded within the telomerase RNA is a template sequence for telomere synthesis. We have characterized the structure of the 5' regions of the human and mouse telomerase-RNA genes, and have found a striking difference in the location of the template sequence: Whereas the 5'-end of the human telomerase RNA lies 45 nt from the telomerase-RNA template sequence, the 5'-end of the mouse telomerase RNA lies just 2 nt from the...

  10. Tetrahymena Telomerase Is Active as a Monomer

    OpenAIRE

    Bryan, Tracy M.; Goodrich, Karen J.; Cech, Thomas R.

    2003-01-01

    Telomerase is an enzyme that utilizes an internal RNA molecule as a template for the extension of chromosomal DNA ends. The catalytic core of telomerase consists of the RNA subunit and a protein reverse transcriptase subunit, known as telomerase reverse transcriptase (TERT). It has previously been shown that both yeast and human telomerase can form dimers or multimers in which one RNA in the complex can influence the activity of another. To test the proposal that dimerization might be essenti...

  11. Expression of T-STAR gene is associated with regulation of telomerase activity in human colon cancer cell line HCT-116

    Institute of Scientific and Technical Information of China (English)

    Ling Zhang; Lian Guo; Yong Peng; Bing Chen

    2006-01-01

    AIM: To investigate the effects on telomerase activity of transfection of human T-STAR gene full-length sense cDNA or partial antisense cDNA into human colon cancer cell line HCT-116.METHODS: mRNA and protein expression levels of T-STAR gene were determined by RT-PCR and western blot, and telomerase activity was measured by PCRELISA, after transfection of T-STAR sense or antisense gene into HCT-116 cells with lipofectamine.RESULTS: T-STAR gene expression was enhanced or knocked down both at mRNA and protein levels,and telomerase activity was significantly increased or decreased.CONCLUSION: The T-STAR gene may participate in regulation of telomerase activity in human colon cancer HCT-116 cells in a parallel fashion.

  12. Identification of ATPases pontin and reptin as telomerase components essential for holoenzyme assembly

    OpenAIRE

    Venteicher, Andrew S.; Meng, Zhaojing; Mason, Philip J.; Veenstra, Timothy D.; Artandi, Steven E.

    2008-01-01

    Telomerase is a multi-subunit ribonucleoprotein (RNP) complex that adds telomere repeats to the ends of linear chromosomes. Three essential telomerase components have been identified thus far: the telomerase reverse transcriptase (TERT), the telomerase RNA component (TERC), and the TERC-binding protein dyskerin. Few other proteins are known to be required for human telomerase function, significantly limiting our understanding of both telomerase regulation and mechanisms of telomerase action. ...

  13. MiRNA profile associated with replicative senescence, extended cell culture, and ectopic telomerase expression in human foreskin fibroblasts.

    Directory of Open Access Journals (Sweden)

    Laura N Bonifacio

    Full Text Available Senescence is a highly regulated process that limits cellular replication by enforcing a G1 arrest in response to various stimuli. Replicative senescence occurs in response to telomeric DNA erosion, and telomerase expression can offset replicative senescence leading to immortalization of many human cells. Limited data exists regarding changes of microRNA (miRNA expression during senescence in human cells and no reports correlate telomerase expression with regulation of senescence-related miRNAs. We used miRNA microarrays to provide a detailed account of miRNA profiles for early passage and senescent human foreskin (BJ fibroblasts as well as early and late passage immortalized fibroblasts (BJ-hTERT that stably express the human telomerase reverse transcriptase subunit hTERT. Selected miRNAs that were differentially expressed in senescence were assayed for expression in quiescent cells to identify miRNAs that are specifically associated with senescence-associated growth arrest. From this group of senescence-associated miRNAs, we confirmed the ability of miR-143 to induce growth arrest after ectopic expression in young fibroblasts. Remarkably, miR-143 failed to induce growth arrest in BJ-hTERT cells. Importantly, the comparison of late passage immortalized fibroblasts to senescent wild type fibroblasts reveals that miR-146a, a miRNA with a validated role in regulating the senescence associated secretory pathway, is also regulated during extended cell culture independently of senescence. The discovery that miRNA expression is impacted by expression of ectopic hTERT as well as extended passaging in immortalized fibroblasts contributes to a comprehensive understanding of the connections between telomerase expression, senescence and processes of cellular aging.

  14. Telomerase flies the coop: the telomerase RNA component as a viral-encoded oncogene

    OpenAIRE

    Artandi, Steven E.

    2006-01-01

    Telomerase, the enzyme that elongates our telomeres, is crucial for cancer development based on extensive analyses of human cells, human cancers, and mouse models. New data now suggest that a viral telomerase RNA gene encoded by Marek's disease virus (MDV), an oncogenic herpesvirus of chickens, promotes tumor formation. These findings highlight the importance of telomerase in cancer and raise new questions regarding the mechanisms by which the telomerase RNA component supports tumorigenesis.

  15. Telomere and telomerase in oncology

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Shortening of the telomeric DNA at the chromosome ends is presumed to limit the lifespan of human cells and elicit a signal for the onset of cellular senescence. To continually proliferate across the senescent checkpoint, cells must restore and preserve telomere length. This can be achieved by telomerase, which has the reverse transcriptase activity. Telomerase activity is negative in human normal somatic cells but can be detected in most tumor cells. The enzyme is proposed to be an essential factor in cell immortalization and cancer progression. In this review we discuss the structure and function of telomere and telomerase and thefr roles in cell immortalization and oncogenesis. Simultaneously the experimental studies of telomerase assays for cancer detection and diagnosis are reviewed. Finally, we discuss the potential use of inhibitors of telomerase in anti-cancer therapy.

  16. Immortalization of human umbilical vein endothelial cells with telomerase reverse transcriptase and simian virus 40 large T antigen

    Institute of Scientific and Technical Information of China (English)

    BIAN Chang; ZHAO Kui; TONG Guo-xin; ZHU Yong-liang; CHEN Peng

    2005-01-01

    Objective: To establish normally conditionally-immortalized human umbilical vein endothelial cells (HUVECs) by ectopic expression of the human telomerase catalytic enzyme (hTERT) and simian virus 40 large T (SV40 LT) antigen. Methods:Primary HUVECs were transfected with recombinant retrovirus containing hTERT or SV40 LT respectively. Subsequently drug resistant cell clones were screened and expanded for further studies. Endothelial cell biomarkers were confirmed by examination.Results: The morphological phenotype of the transfected cells was similar to the non-transfected cells. Von Willebrand factor,hTERT and SV40 LT could be detected in transfected HUVECs. Moreover, higher telomerase activity in transfected cells was maintained for over 50 population doublings compared with only low level of endogenous telomerase transiently at early population doublings in primary HUVECs. When exposed to TNF-α (tumor necrosis factor-α), the expression of E-selectin in transfected cells was significantly up-regulated, but no alteration of endothelial lipase was found. Conclusion: Ectopic coexpression of hTERT and SV40 LT can effectively immortalize HUVECs without tumorigenicity in vitro. Immortalized HUVECs may be an ideal target of further molecular function studies.

  17. Expression of the telomerase catalytic subunit, hTERT, induces resistance to transforming growth factor β growth inhibition in p16INK4A(−) human mammary epithelial cells

    OpenAIRE

    Stampfer, Martha R.; Garbe, James; Levine, Gerri; Lichtsteiner, Serge; Vasserot, Alain P.; Yaswen, Paul

    2001-01-01

    Failures to arrest growth in response to senescence or transforming growth factor β (TGF-β) are key derangements associated with carcinoma progression. We report that activation of telomerase activity may overcome both inhibitory pathways. Ectopic expression of the human telomerase catalytic subunit, hTERT, in cultured human mammary epithelial cells (HMEC) lacking both telomerase activity and p16INK4A resulted in gaining the ability to maintain indefinite growth in the ab...

  18. Establishment and transformation of telomerase-immortalized human small airway epithelial cells by heavy ions

    Science.gov (United States)

    Zhao, Y. L.; Piao, C. Q.; Hei, T. K.

    Previous studies from this laboratory have identified a number of causally linked genes including the novel tumor suppressor Betaig-h3 that were differentially expressed in radiation induced tumorigenic BEP2D cells. To extend these studies using a genomically more stable bronchial cell line, we show here that ectopic expression of the catalytic subunit of telomerase (hTERT) in primary human small airway epithelial (SAE) cells resulted in the generation of several clonal cell lines that have been continuously in culture for more than 250 population doublings and are considered immortal. Comparably-treated control SAE cells infected with only the viral vector senesced after less than 10 population doublings. The immortalized clones demonstrated anchorage dependent growth and are non-tumorigenic in nude mice. These cells show no alteration in the p53 gene but a decrease in p16 expression. Exponentially growing SAEh cells were exposed to graded doses of 1 GeV/nucleon of 56Fe ions accelerated at the Brookhaven National Laboratory. Irradiated cells underwent gradual phenotypic alterations after extensive in vitro cultivation. Transformed cells developed through a series of successive steps before becoming anchorage independent in semisolid medium. These findings indicate that hTERT-immortalized cells, being diploid and chromosomal stable, should be a useful model in assessing mechanism of radiation carcinogenesis.

  19. Telomerase reverse transcriptase expression protects transformed human cells against DNA-damaging agents, and increases tolerance to chromosomal instability.

    Science.gov (United States)

    Fleisig, H B; Hukezalie, K R; Thompson, C A H; Au-Yeung, T T T; Ludlow, A T; Zhao, C R; Wong, J M Y

    2016-01-14

    Reactivation of telomerase reverse transcriptase (TERT) expression is found in more than 85% of human cancers. The remaining cancers rely on the alternative lengthening of telomeres (ALT), a recombination-based mechanism for telomere-length maintenance. Prevalence of TERT reactivation over the ALT mechanism was linked to secondary TERT function unrelated to telomere length maintenance. To characterize this non-canonical function, we created a panel of ALT cells with recombinant expression of TERT and TERT variants: TERT-positive ALT cells showed higher tolerance to genotoxic insults compared with their TERT-negative counterparts. We identified telomere synthesis-defective TERT variants that bestowed similar genotoxic stress tolerance, indicating that telomere synthesis activity is dispensable for this survival phenotype. TERT expression improved the kinetics of double-strand chromosome break repair and reduced DNA damage-related nuclear division abnormalities, a phenotype associated with ALT tumors. Despite this reduction in cytological abnormalities, surviving TERT-positive ALT cells were found to have gross chromosomal instabilities. We sorted TERT-positive cells with cytogenetic changes and followed their growth. We found that the chromosome-number changes persisted, and TERT-positive ALT cells surviving genotoxic events propagated through subsequent generations with new chromosome numbers. Our data confirm that telomerase expression protects against double-strand DNA (dsDNA)-damaging events, and show that this protective function is uncoupled from its role in telomere synthesis. TERT expression promotes oncogene-transformed cell growth by reducing the inhibitory effects of cell-intrinsic (telomere attrition) and cell-extrinsic (chemical- or metabolism-induced genotoxic stress) challenges. These data provide the impetus to develop new therapeutic interventions for telomerase-positive cancers through simultaneous targeting of multiple telomerase activities. PMID

  20. In vitro anti-telomerase activity of novel lycopene-loaded nanospheres in the human leukemia cell line K562

    Science.gov (United States)

    Gharib, Amir; Faezizadeh, Zohreh

    2014-01-01

    Background: Lycopene, a plant carotenoid, has potent effects against the various types of cancer cells. To date, the effect of lycopene in the free and encapsulated forms on the telomerase activity in human leukemia cell line K562 have not been investigated. The aim of the present study was to prepare a novel lycopene-loaded nanosphere and compare its anti-telomearse activity in K562 cell line with those of free lycopene. Materials and Methods: The lycopene-loaded nanospheres were prepared by nanoprecipitation method. The lycopene entrapment efficacy was measured by high-performance liquid chromatography (HPLC) method. The anti-proliferation effect of the lycopene in the free and encapsulated forms in the different times (0-72 h) and the different doses (0-100 μg/ml) on K562 cell line was studied using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay. The changes of telomerase activity, following treatment with the lycopene in the free and encapsulated forms, were detected using the telomeric repeat amplification protocol-enzyme-linked immunosorbent assay. Results: The entrapment efficacy of lycopene was 78.5% ± 2. Treatment of the K562 cell line with lycopene, in particular in encapsulated form, resulted in a significant inhibition of the cell growth and increasing of percentage of apoptotic cells. It has also been observed that the telomerase activity in the lycopene-loaded nanospheres-treated cells was significantly inhibited in a dose and time-dependent manner. Conclusion: Our data suggest a novel mechanism in the anti-cancer activity of the lycopene, in particular in encapsulated form, and could be provided a basis for the future development of anti-telomerase therapies. PMID:24914298

  1. Forms and Functions of Telomerase RNA

    Science.gov (United States)

    Collins, Kathleen

    Telomerase adds single-stranded telomeric DNA repeats to chromosome ends. Unlike other polymerases involved in genome replication, telomerase synthe¬sizes DNA without use of a DNA template. Instead, the enzyme active site copies a template carried within the integral RNA subunit of the telomerase ribonucleo-protein (RNP) complex. In addition to providing a template, telomerase RNA has non-template motifs with critical functions in the catalytic cycle of repeat synthesis. In its complexity of structure and function, telomerase RNA resembles the non-coding RNAs of RNP machines like the ribosome and spliceosome that evolved from catalytic RNAs of the RNA World. However, unlike these RNPs, telomerase evolved its RNP identity after advent of the Protein World. Insights about telomer-ase have broad significance for understanding non-coding RNA biology as well as chromosome end maintenance and human disease.

  2. PREPARATION AND CHARACTERIZATION OF MONOCLONAL ANTIBODY AGAINST HUMAN TELOMERASE REVERSE TRANSCRIPTASE

    Institute of Scientific and Technical Information of China (English)

    王俊梅; 张波; 杨邵敏; 韩继生; 李冰思; 侯琳

    2003-01-01

    Objective. To develop monoclonal antibodies against the catalytic subunit of human telomerase reverse transcriptase (hTERT) for its expression detection of human tumors. Methods. A dominant epitope in hTERT (peptide hTERT7)was automatically synthesized based on Fmoc method, and was used to immunize Balb/c mice. Hybridomas were generated and screened by ELISA for specific monoclonal antibodies, and the characterization was performed by Western blotting and immunohistochemical staining. The heavy chain variable region of antibody was cloned by RT-PCR and sequenced. Results. Antigenic peptide hTERT7 was synthesized and confirmed by MALDI-TOF-MS and HPLC analysis. One hybridoma cell line secreting anti-hTERT7 antibodies designated as M2 was established after primary screening and consequent 3 rounds of limited dilution. M2 was IgG1 in isotyping. The competi tive assay showed that the M2 antibody was hTERT7 -specific, and the affinity constant was about 1×106 mol-1. The antibody reacted with cell extracts from HeLa cancer cells but not with those from normal 2BS cells in ELISA assay. For in situ staining of immunohistochemistry, the positive staining presented in the nuclear compartment of HeLa, while 2BS was negative. The heavy chain variable region from M2 re vealed that the monoclonal antibody was mouse origin. Conclusions. The developed mouse monoclonal antibody is hTERT-specific and able to recognize native cellular hTERT in ELISA and immunohistochemistry, which makes the immuno-detection of telom erase hTERT expression in cancer cells or tissues possible.

  3. Cytotoxic T cell responses to human telomerase reverse transcriptase in patients with hepatocellular carcinoma.

    Science.gov (United States)

    Mizukoshi, Eishiro; Nakamoto, Yasunari; Marukawa, Yohei; Arai, Kuniaki; Yamashita, Tatsuya; Tsuji, Hirokazu; Kuzushima, Kiyotaka; Takiguchi, Masafumi; Kaneko, Shuichi

    2006-06-01

    Human telomerase reverse transcriptase, hTERT, has been identified as the catalytic enzyme required for telomere elongation. hTERT is expressed in most tumor cells but seldom expressed in most human adult cells. It has been reported that 80% to 90% of hepatocellular carcinomas (HCCs) express hTERT, making the enzyme a potential target in immunotherapy for HCC. In the current study, we identified hTERT-derived, HLA-A*2402-restricted cytotoxic T cell (CTL) epitopes and analyzed hTERT-specific CTL responses in patients with HCC. Peptides containing the epitopes showed high affinity to bind HLA-A*2402 in a major histocompatibility complex binding assay and were able to induce hTERT-specific CTLs in both hTERT cDNA-immunized HLA-A*2402/Kb transgenic mice and patients with HCC. The CTLs were able to kill hepatoma cell lines depending on hTERT expression levels in an HLA-A*2402-restricted manner and induced irrespective of hepatitis viral infection. The number of single hTERT epitope-specific T cells detected by ELISPOT assay was 10 to 100 specific cells per 3 x 10(5) PBMCs, and positive T cell responses were observed in 6.9% to 12.5% of HCC patients. hTERT-specific T cell responses were observed even in the patients with early stages of HCC. The frequency of hTERT/tetramer+ CD8+ T cells in the tumor tissue of patients with HCC was quite high, and they were functional. In conclusion, these results suggest that hTERT is an attractive target for T-cell-based immunotherapy for HCC, and the identified hTERT epitopes may be valuable both for immunotherapy and for analyzing host immune responses to HCC. PMID:16729333

  4. Cell proliferation in the presence of telomerase.

    Directory of Open Access Journals (Sweden)

    Krastan B Blagoev

    Full Text Available BACKGROUND: Telomerase, which is active early in development and later in stem and germline cells, is also active in the majority of human cancers. One of the known functions of telomerase is to extend the ends of linear chromosomes, countering their gradual shortening at each cell division due to the end replication problem and postreplication processing. Telomerase concentration levels vary between different cell types as well as between different tumors. In addition variable telomerase concentrations will exist in different cells in the same tumor when telomerase inhibitors are used, because of limitations of drug delivery in tissue. Telomerase extends short telomeres more frequently than long telomeres and the relation between the extension frequency and the telomere length is nonlinear. METHODOLOGY/PRINCIPAL FINDINGS: Here, the biological data of the nonlinear telomerase-telomere dynamics is incorporated in a mathematical theory to relate the proliferative potential of a cell to the telomerase concentration in that cell. The main result of the paper is that the proliferative capacity of a cell grows exponentially with the telomerase concentration. CONCLUSIONS/SIGNIFICANCE: The theory presented here suggests that long term telomerase inhibition in every cancer progenitor or cancer stem cell is needed for successful telomere targeted cancer treatment. This theory also can be used to plan and assess the results of clinical trials targeting telomerase.

  5. Efficient telomerase inhibition in human non-small cell lung cancer cells by liposomal delivery of 2'-O-methyl-RNA.

    Science.gov (United States)

    Beisner, Julia; Dong, Meng; Taetz, Sebastian; Piotrowska, Kamilla; Kleideiter, Elke; Friedel, Godehard; Schaefer, Ulrich; Lehr, Claus-Michael; Klotz, Ulrich; Mürdter, Thomas E

    2009-05-01

    The antisense oligonucleotide 2'-O-methyl-RNA is a selective telomerase inhibitor targeting the telomerase RNA component and represents a potential candidate for anticancer therapy. The poor cellular uptake of 2'-O-methyl-RNA is a limiting factor that may contribute to the lack of functional efficacy. To improve delivery of 2'-O-methyl-RNA and consequently antitumoral efficiency in human lung cancer cells, we have investigated several transfection reagents. The transfection reagents DOTAP, MegaFectin 60, SuperFect, FuGENE 6 and MATra-A were tested for intracellular delivery. A FAM-labeled 2'-O-methyl-RNA was used to assess the intracellular distribution by confocal laser scanning microscopy in A549 human non-small cell lung cancer cells. Telomerase activity was measured using the telomeric repeat amplification protocol. Cell viability after transfection was quantified by the MTT assay. All transfection reagents enhanced 2'-O-methyl-RNA uptake in A549 cells but the cationic lipid reagents DOTAP and MegaFectin 60 were most efficient in the delivery of 2'-O-methyl-RNA resulting in telomerase inhibition. Among both DOTAP exhibited the lowest cytotoxicity. Our experiments show that DOTAP is the most suitable transfection reagent for the delivery of 2'-O-methyl-RNA in human lung cancer cells according to its relatively low cytotoxicity and its ability to promote efficient uptake leading to the inhibition of telomerase. PMID:18803262

  6. Real-time determination of human telomerase reverse transcriptase mRNA in gastric cancer

    Institute of Scientific and Technical Information of China (English)

    Li-Hua Hu; Feng-Hua Chen; Yi-Rong Li; Lin Wang

    2004-01-01

    AIM: To set up a real-time fluorescent quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay,to detect human telomerase reverse transcriptase (hTERT)messenger RNA in gastric carcinomas, and to evaluate quantitative determination of hTERT mRNA in the diagnostic value of gastric carcinomas, and to analyze the correlation between the expression level of hTERT mRNA and dinicopathological parameters in patients with gastric cancer.METHODS: A real-time quantitative RT-PCR (RQ-PCR)based on TaqMan fluorescence methodoloogy and the LightCyder system was used to quantify the full range of hTERT mRNA copy numbers in 35 samples of gastric carcinomas and corresponding adjacent non-cancerous tissues. The normalized hTERT (NhTERT) was standardized by quantifying the number of GAPDH transcripts as internal control and expressed as 100× (hTERT/GAPDH) ratio. Variables were analyzed by the Student's t-test, χ2 test and Fisher's exact test.RESULTS: NhTERT from gastric carcinomas and corresponding adjacent non-cancerous tissues was 6.27±0.89 and 0.93±0.18,respectively (t= 12.76, P<0.001). There was no significant association between gastric cancer hTERT mRNA expression level and patient's age, gender, tumor size, location and stage (pTNM), but a significant correlation was found between hTERT mRNA expression level in gastric carcinomas and the degree of differentiation.CONCLUSION: Quantitative determination of hTERT mRNA by RQ-PCR is a rapid and sensitive method. hTERT might be a potential biomarker for the early detection of gastric cancer.

  7. Leptin as a critical regulator of hepatocellular carcinoma development through modulation of human telomerase reverse transcriptase

    Directory of Open Access Journals (Sweden)

    Stefanou Nikolaos

    2010-08-01

    Full Text Available Abstract Background Numerous epidemiological studies have documented that obesity is associated with hepatocellular carcinoma (HCC. The aim of this study was to investigate the biological actions regulated by leptin, the obesity biomarker molecule, and its receptors in HCC and the correlation between leptin and human telomerase reverse transcriptase (hTERT, a known mediator of cellular immortalization. Methods We investigated the relationship between leptin, leptin receptors and hTERT mRNA expression in HCC and healthy liver tissue samples. In HepG2 cells, chromatin immunoprecipitation assay was used to study signal transducer and activator of transcription-3 (STAT3 and myc/mad/max transcription factors downstream of leptin which could be responsible for hTERT regulation. Flow cytometry was used for evaluation of cell cycle modifications and MMP1, 9 and 13 expression after treatment of HepG2 cells with leptin. Blocking of leptin's expression was achieved using siRNA against leptin and transfection with liposomes. Results We showed, for the first time, that leptin's expression is highly correlated with hTERT expression levels in HCC liver tissues. We also demonstrated in HepG2 cells that leptin-induced up-regulation of hTERT and TA was mediated through binding of STAT3 and Myc/Max/Mad network proteins on hTERT promoter. We also found that leptin could affect hepatocellular carcinoma progression and invasion through its interaction with cytokines and matrix mettaloproteinases (MMPs in the tumorigenic microenvironment. Furthermore, we showed that histone modification contributes to leptin's gene regulation in HCC. Conclusions We propose that leptin is a key regulator of the malignant properties of hepatocellular carcinoma cells through modulation of hTERT, a critical player of oncogenesis.

  8. Leptin as a critical regulator of hepatocellular carcinoma development through modulation of human telomerase reverse transcriptase

    International Nuclear Information System (INIS)

    Numerous epidemiological studies have documented that obesity is associated with hepatocellular carcinoma (HCC). The aim of this study was to investigate the biological actions regulated by leptin, the obesity biomarker molecule, and its receptors in HCC and the correlation between leptin and human telomerase reverse transcriptase (hTERT), a known mediator of cellular immortalization. We investigated the relationship between leptin, leptin receptors and hTERT mRNA expression in HCC and healthy liver tissue samples. In HepG2 cells, chromatin immunoprecipitation assay was used to study signal transducer and activator of transcription-3 (STAT3) and myc/mad/max transcription factors downstream of leptin which could be responsible for hTERT regulation. Flow cytometry was used for evaluation of cell cycle modifications and MMP1, 9 and 13 expression after treatment of HepG2 cells with leptin. Blocking of leptin's expression was achieved using siRNA against leptin and transfection with liposomes. We showed, for the first time, that leptin's expression is highly correlated with hTERT expression levels in HCC liver tissues. We also demonstrated in HepG2 cells that leptin-induced up-regulation of hTERT and TA was mediated through binding of STAT3 and Myc/Max/Mad network proteins on hTERT promoter. We also found that leptin could affect hepatocellular carcinoma progression and invasion through its interaction with cytokines and matrix mettaloproteinases (MMPs) in the tumorigenic microenvironment. Furthermore, we showed that histone modification contributes to leptin's gene regulation in HCC. We propose that leptin is a key regulator of the malignant properties of hepatocellular carcinoma cells through modulation of hTERT, a critical player of oncogenesis

  9. Correlation of Bmi-1 expression and telomerase activity in human ovarian cancer

    NARCIS (Netherlands)

    Zhang, F. B.; Sui, L. H.; Xin, T.

    2008-01-01

    This study investigates the correlation between the oncoprotein Bmi-1 and telomerase activity in ovarian cancer. A real-time polymerase chain reaction (PCR) method is used to detect the messenger RNA (mRNA) expression of Bmi-1 protein in 47 ovarian epithelial cancer cases, and immunohistochemistry i

  10. In vitro anti-telomerase activity of novel lycopene-loaded nanospheres in the human leukemia cell line K562

    OpenAIRE

    Amir Gharib; Zohreh Faezizadeh

    2014-01-01

    Background: Lycopene, a plant carotenoid, has potent effects against the various types of cancer cells. To date, the effect of lycopene in the free and encapsulated forms on the telomerase activity in human leukemia cell line K562 have not been investigated. The aim of the present study was to prepare a novel lycopene-loaded nanosphere and compare its anti-telomearse activity in K562 cell line with those of free lycopene. Materials and Methods: The lycopene-loaded nanospheres were prepared by...

  11. Hepatitis B virus core protein enhances human telomerase reverse transcriptase expression and hepatocellular carcinoma cell proliferation in a c-Ets2-dependent manner.

    Science.gov (United States)

    Gai, Xiaoxiao; Zhao, Peiqing; Pan, Yingfang; Shan, Haixia; Yue, Xuetian; Du, Juan; Zhang, Zhenyu; Liu, Peng; Ma, Hongxin; Guo, Min; Yang, Xiaoyun; Sun, Wensheng; Gao, Lifen; Ma, Chunhong; Liang, Xiaohong

    2013-07-01

    Hepatitis B virus core protein can regulate viral replication and host gene expression. However, it is unclear whether and how hepatitis B virus core protein regulates hepatocellular carcinoma cell proliferation. Induction of hepatitis B virus core protein over-expression significantly enhanced the proliferation of hepatocellular carcinoma cells, while knockdown of hepatitis B virus core protein expression inhibited the proliferation of hepatocellular carcinoma cells. Altered hepatitis B virus core protein expression significantly changed the growth of implanted hepatocellular carcinoma in vivo. Microarray analysis indicated that hepatitis B virus core protein up-regulated human telomerase reverse transcriptase expression, which was further validated by over-expression and knockdown assays in vitro. Furthermore, knockdown of human telomerase reverse transcriptase expression mitigated the hepatitis B virus core protein-enhanced hepatocellular carcinoma cell proliferation and clone formation in vitro. Luciferase assays indicated that hepatitis B virus core protein enhanced the promoter activity of human telomerase reverse transcriptase, which was dependent on the binding of c-Ets2 to the promoter region between -192 and -187. In addition, hepatitis B virus core protein enhanced human telomerase reverse transcriptase transcription in HepG2 cells, but not in the c-Ets2-silencing HepG2 cells. Moreover, hepatitis B virus core protein promoted c-Ets2 nuclear translocation. Finally, significantly higher levels of human telomerase reverse transcriptase expression and nuclear c-Ets2 accumulation were detected in hepatitis B virus core protein-positive hepatocellular carcinoma samples. Our findings demonstrate that hepatitis B virus core protein promotes hepatocellular carcinoma cell proliferation by up-regulating the c-Ets2-dependent expression of human telomerase reverse transcriptase. PMID:23542016

  12. Study on the immune responses against pancreatic cancer induced by mucin 4 and human telomerase reverse transcriptase mRNA co-transfected dendritic cells in vitro

    Institute of Scientific and Technical Information of China (English)

    陈江

    2014-01-01

    Objective To investigate the anti-tumor immune response induced by human pancreatic cancer mucin 4mRNA and human telomerase reverse transcriptase(hTERT)mRNA cotransfected dendritic cells(DC),and to provide the experimental evidences for the treatment of pancreatic cancer with multi-epitope loaded DC vaccine.Methods DC were isolated from peripheral DC.

  13. Estrogen induction of telomerase activity through regulation of the mitogen-activated protein kinase (MAPK dependent pathway in human endometrial cancer cells.

    Directory of Open Access Journals (Sweden)

    Chunxiao Zhou

    Full Text Available Given that prolonged exposure to estrogen and increased telomerase activity are associated with endometrial carcinogenesis, our objective was to evaluate the interaction between the MAPK pathway and estrogen induction of telomerase activity in endometrial cancer cells. Estradiol (E2 induced telomerase activity and hTERT mRNA expression in the estrogen receptor (ER-α positive, Ishikawa endometrial cancer cell line. UO126, a highly selective inhibitor of MEK1/MEK2, inhibited telomerase activity and hTERT mRNA expression induced by E2. Similar results were also found after transfection with ERK 1/2-specific siRNA. Treatment with E2 resulted in rapid phosphorylation of p44/42 MAPK and increased MAPK activity which was abolished by UO126. The hTERT promoter contains two estrogen response elements (EREs, and luciferase assays demonstrate that these EREs are activated by E2. Exposure to UO126 or ERK 1/2-specific siRNA in combination with E2 counteracted the stimulatory effect of E2 on luciferase activity from these EREs. These findings suggest that E2-induction of telomerase activity is mediated via the MAPK pathway in human endometrial cancer cells.

  14. Telomere and Telomerase Therapeutics in Cancer

    Science.gov (United States)

    Xu, Yucheng; Goldkorn, Amir

    2016-01-01

    Telomerase is a reverse transcriptase capable of utilizing an integrated RNA component as a template to add protective tandem telomeric single strand DNA repeats, TTAGGG, to the ends of chromosomes. Telomere dysfunction and telomerase reactivation are observed in approximately 90% of human cancers; hence, telomerase activation plays a unique role as a nearly universal step on the path to malignancy. In the past two decades, multiple telomerase targeting therapeutic strategies have been pursued, including direct telomerase inhibition, telomerase interference, hTERT or hTERC promoter driven therapy, telomere-based approaches, and telomerase vaccines. Many of these strategies have entered clinical development, and some have now advanced to phase III clinical trials. In the coming years, one or more of these new telomerase-targeting drugs may be expected to enter the pharmacopeia of standard care. Here, we briefly review the molecular functions of telomerase in cancer and provide an update about the preclinical and clinical development of telomerase targeting therapeutics. PMID:27240403

  15. Telomere and Telomerase Therapeutics in Cancer

    Directory of Open Access Journals (Sweden)

    Yucheng Xu

    2016-05-01

    Full Text Available Telomerase is a reverse transcriptase capable of utilizing an integrated RNA component as a template to add protective tandem telomeric single strand DNA repeats, TTAGGG, to the ends of chromosomes. Telomere dysfunction and telomerase reactivation are observed in approximately 90% of human cancers; hence, telomerase activation plays a unique role as a nearly universal step on the path to malignancy. In the past two decades, multiple telomerase targeting therapeutic strategies have been pursued, including direct telomerase inhibition, telomerase interference, hTERT or hTERC promoter driven therapy, telomere-based approaches, and telomerase vaccines. Many of these strategies have entered clinical development, and some have now advanced to phase III clinical trials. In the coming years, one or more of these new telomerase-targeting drugs may be expected to enter the pharmacopeia of standard care. Here, we briefly review the molecular functions of telomerase in cancer and provide an update about the preclinical and clinical development of telomerase targeting therapeutics.

  16. Telomere and Telomerase Therapeutics in Cancer.

    Science.gov (United States)

    Xu, Yucheng; Goldkorn, Amir

    2016-01-01

    Telomerase is a reverse transcriptase capable of utilizing an integrated RNA component as a template to add protective tandem telomeric single strand DNA repeats, TTAGGG, to the ends of chromosomes. Telomere dysfunction and telomerase reactivation are observed in approximately 90% of human cancers; hence, telomerase activation plays a unique role as a nearly universal step on the path to malignancy. In the past two decades, multiple telomerase targeting therapeutic strategies have been pursued, including direct telomerase inhibition, telomerase interference, hTERT or hTERC promoter driven therapy, telomere-based approaches, and telomerase vaccines. Many of these strategies have entered clinical development, and some have now advanced to phase III clinical trials. In the coming years, one or more of these new telomerase-targeting drugs may be expected to enter the pharmacopeia of standard care. Here, we briefly review the molecular functions of telomerase in cancer and provide an update about the preclinical and clinical development of telomerase targeting therapeutics. PMID:27240403

  17. Discovery of ligands for a novel target, the human telomerase RNA, based on flexible-target virtual screening and NMR.

    Science.gov (United States)

    Pinto, Irene Gómez; Guilbert, Christophe; Ulyanov, Nikolai B; Stearns, Jay; James, Thomas L

    2008-11-27

    The human ribonucleoprotein telomerase is a validated anticancer drug target, and hTR-P2b is a part of the human telomerase RNA (hTR) essential for its activity. Interesting ligands that bind hTR-P2b were identified by iteratively using a tandem structure-based approach: docking of potential ligands from small databases to hTR-P2b via the program MORDOR, which permits flexibility in both ligand and target, with subsequent NMR screening of high-ranking compounds. A high percentage of the compounds tested experimentally were found via NMR to bind to the U-rich region of hTR-P2b; most have MW < 500 Da and are from different compound classes, and several possess a charge of 0 or +1. Of the 48 ligands identified, 24 exhibit a decided preference to bind hTR-P2b RNA rather than A-site rRNA and 10 do not bind A-site rRNA at all. Binding affinity was measured by monitoring RNA imino proton resonances for some of the compounds that showed hTR binding preference. PMID:18950148

  18. Telomerase activity in 144 brain tumours.

    OpenAIRE

    Sano, T; Asai, A.; Mishima, K.; Fujimaki, T.; Kirino, T.

    1998-01-01

    Unlimited proliferation in immortalized cells is believed to be highly dependent on the activity of telomerase, a ribonucleoprotein that synthesizes telomeric repeats onto chromosome ends. Using a polymerase chain reaction-based telomeric repeat amplification protocol (TRAP) assay, we analysed telomerase activity in 99 benign and 45 malignant brain tumours. The TRAP assay results were quantitated by normalizing the telomerase activity of each specimen to that of human glioma cell line T98G to...

  19. Telomerase mutations in smokers with severe emphysema

    OpenAIRE

    Stanley, Susan E.; Chen, Julian J. L.; Podlevsky, Joshua D.; Alder, Jonathan K; Hansel, Nadia N.; Rasika A Mathias; Qi, Xiaodong; Rafaels, Nicholas M.; Wise, Robert A.; Silverman, Edwin K.; Kathleen C. Barnes; Armanios, Mary

    2014-01-01

    Mutations in the essential telomerase genes TERT and TR cause familial pulmonary fibrosis; however, in telomerase-null mice, short telomeres predispose to emphysema after chronic cigarette smoke exposure. Here, we tested whether telomerase mutations are a risk factor for human emphysema by examining their frequency in smokers with chronic obstructive pulmonary disease (COPD). Across two independent cohorts, we found 3 of 292 severe COPD cases carried deleterious mutations in TERT (1%). This p...

  20. Zoning of mucosal phenotype, dysplasia, and telomerase activity measured by telomerase repeat assay protocol in Barrett's esophagus

    NARCIS (Netherlands)

    Going, JJ; Fletcher-Monaghan, AJ; Neilson, L; Wisman, BA; van der Zee, A; Stuart, RC; Keith, WN

    2004-01-01

    Glandular dysplasia in Barrett's esophagus may regress spontaneously but can also progress to cancer. The human telomerase RNA template and the human telomerase reverse transcriptase enzyme which do not, of themselves, correlate strongly with telomerase activity, are too often overexpressed in Barre

  1. Inter-telomeric recombination is present in telomerase-positive human cells

    OpenAIRE

    Dlaska, Margit; Schöffski, Patrick; Bechter, Oliver E.

    2013-01-01

    Immortal cells require a mechanism of telomere length control in order to divide infinitely. One mechanism is telomerase, an enzyme that compensates the loss of telomeric DNA. The second mechanism is the alternative lengthening of telomeres (ALT) pathway. In ALT pathway cells, homologous recombination between telomeric DNA is the mechanism by which telomere homeostasis is achieved. We developed a novel homologous recombination reporter system that is able to measure inter-telomeric recombinat...

  2. Detection of telomerase, its components, and human papillomavirus in cervical scrapings as a tool for triage in women with cervical dysplasia

    NARCIS (Netherlands)

    Reesink-Peters, N.; Helder, M N; Wisman, G B A; Knol, A J; Koopmans, S; Boezen, H M; Schuuring, E; Hollema, H; de Vries, Elisabeth G. E.; de Jong, Steven; van der Zee, A G J

    2003-01-01

    AIM: To examine whether the detection of either telomerase and its components or high risk human papillomavirus (HPV) are of value in predicting the presence of cervical intraepithelial neoplasia (CIN) grade II/III in women referred because of cervical cytology reports showing at most moderate dyska

  3. Telomerase in (pre)neoplastic cervical disease

    NARCIS (Netherlands)

    Wisman, GBA; De Jong, S; Meersma, GJ; Helder, MN; Hollema, H; de Vries, EGE; Keith, WN; van der Zee, AGJ

    2000-01-01

    This study was performed to determine upregulation of the human telomerase RNA component (hTR) and mRNA of the catalytic subunit of telomerase (hTERT) in (pre)malignant cervical lesions, to analyze possible intralesional heterogeneity of hTR expression, and to relate hTR and hTERT mRNA levels to tel

  4. The Telomerase Database

    OpenAIRE

    Podlevsky, Joshua D.; Bley, Christopher J.; Omana, Rebecca V.; Qi, Xiaodong; Chen, Julian J.-L.

    2007-01-01

    Telomerase is a ribonucleoprotein enzyme that extends DNA at the chromosome ends in most eukaryotes. Since 1985, telomerase has been studied intensively and components of the telomerase complex have been identified from over 160 eukaryotic species. In the last two decades, there has been a growing interest in studying telomerase owing to its vital role in chromosome stability and cellular immortality. To keep up with the remarkable explosion of knowledge about telomerase, we compiled informat...

  5. Determinants in mammalian telomerase RNA that mediate enzyme processivity and cross-species incompatibility

    OpenAIRE

    Chen, Jiunn-Liang; Greider, Carol W

    2003-01-01

    Telomerase contains two essential components: an RNA molecule that templates telomeric repeat synthesis and a catalytic protein component. Human telomerase is processive, while the mouse enzyme has much lower processivity. We have identified nucleotide determinants in the telomerase RNA that are responsible for this difference in processivity. Mutations adjacent to the template region of human and mouse telomerase RNA significantly altered telomerase processivity both in vitro and in vivo. We...

  6. Telomerase lost?

    Czech Academy of Sciences Publication Activity Database

    Mason, J. M.; Randall, T. A.; Čapková Frydrychová, Radmila

    2016-01-01

    Roč. 125, č. 1 (2016), s. 65-73. ISSN 0009-5915 R&D Projects: GA ČR GA14-07172S Grant ostatní: GA JU(CZ) 052/2013/P; GA JU(CZ) 038/2014/P; European Union Seventh Framework Programme(CZ) 316304 Institutional support: RVO:60077344 Keywords : telomerase * DNA sequences * Bombyx mori Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.602, year: 2014 http://link.springer.com/article/10.1007%2Fs00412-015-0528-7

  7. Analysis of Genomic Integrity and p53-Dependent G1 Checkpoint in Telomerase-Induced Extended-Life-Span Human Fibroblasts

    OpenAIRE

    Vaziri, Homayoun; Jeremy A Squire; Pandita, Tej K.; Bradley, Grace; Kuba, Robert M.; Zhang, Haihua; Gulyas, Sandor; Hill, Richard P.; Nolan, Garry P.; Benchimol, Samuel

    1999-01-01

    Life span determination in normal human cells may be regulated by nucleoprotein structures called telomeres, the physical ends of eukaryotic chromosomes. Telomeres have been shown to be essential for chromosome stability and function and to shorten with each cell division in normal human cells in culture and with age in vivo. Reversal of telomere shortening by the forced expression of telomerase in normal cells has been shown to elongate telomeres and extend the replicative life span (H. Vazi...

  8. Designed modulation of sex steroid signaling inhibits telomerase activity and proliferation of human prostate cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Vikas; Sharma, Vikas; Singh, Vishal [Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow 226 031 (India); Sharma, Siddharth; Bishnoi, Ajay Kumar [Division of Medicinal and Process Chemistry, CSIR-Central Drug Research Institute, Lucknow 226 031 (India); Chandra, Vishal; Maikhuri, J.P.; Dwivedi, Anila [Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow 226 031 (India); Kumar, Atul [Division of Medicinal and Process Chemistry, CSIR-Central Drug Research Institute, Lucknow 226 031 (India); Gupta, Gopal, E-mail: g_gupta@cdri.res.in [Division of Endocrinology, CSIR-Central Drug Research Institute, Lucknow 226 031 (India)

    2014-10-15

    The predominant estrogen-receptor (ER)-β signaling in normal prostate is countered by increased ER-α signaling in prostate cancer (CaP), which in association with androgen-receptor (AR) signaling results in pathogenesis of the disease. However CaP treatments mostly target AR signaling which is initially effective but eventually leads to androgen resistance, hence simultaneous targeting of ERs has been proposed. A novel series of molecules were designed with multiple sex-steroid receptor modulating capabilities by coalescing the pharmacophores of known anti-CaP molecules that act via modulation of ER(α/β) and/or AR, viz. 3,3′diindolylmethane (DIM), mifepristone, toremifene, tamoxifen and raloxifene. N,N-diethyl-4-((2-(4-methoxyphenyl)-1H-indol-3-yl)methyl) aniline (DIMA) was identified as the most promising structure of this new series. DIMA increased annexin-V labelling, cell-cycle arrest and caspase-3 activity, and decreased expression of AR and prostate specific antigen in LNCaP cells, in vitro. Concurrently, DIMA increased ER-β, p21 and p27 protein levels in LNCaP cells and exhibited ∼ 5 times more selective binding for ER-β than ER-α, in comparison to raloxifene. DIMA exhibited a dose-dependent ER-β agonism and ER-α antagonism in classical gene reporter assay and decreased hTERT (catalytic subunit of telomerase) transcript levels in LNCaP at 3.0 μM (P < 0.05). DIMA also dose-dependently decreased telomerase enzyme activity in prostate cancer cells. It is thus concluded that DIMA acts as a multi-steroid receptor modulator and effectively inhibits proliferation of prostate cancer cells through ER-β mediated telomerase inhibition, by countering actions of ER-α and AR. Its unique molecular design can serve as a lead structure for generation of potent agents against endocrine malignancies like the CaP.

  9. Designed modulation of sex steroid signaling inhibits telomerase activity and proliferation of human prostate cancer cells

    International Nuclear Information System (INIS)

    The predominant estrogen-receptor (ER)-β signaling in normal prostate is countered by increased ER-α signaling in prostate cancer (CaP), which in association with androgen-receptor (AR) signaling results in pathogenesis of the disease. However CaP treatments mostly target AR signaling which is initially effective but eventually leads to androgen resistance, hence simultaneous targeting of ERs has been proposed. A novel series of molecules were designed with multiple sex-steroid receptor modulating capabilities by coalescing the pharmacophores of known anti-CaP molecules that act via modulation of ER(α/β) and/or AR, viz. 3,3′diindolylmethane (DIM), mifepristone, toremifene, tamoxifen and raloxifene. N,N-diethyl-4-((2-(4-methoxyphenyl)-1H-indol-3-yl)methyl) aniline (DIMA) was identified as the most promising structure of this new series. DIMA increased annexin-V labelling, cell-cycle arrest and caspase-3 activity, and decreased expression of AR and prostate specific antigen in LNCaP cells, in vitro. Concurrently, DIMA increased ER-β, p21 and p27 protein levels in LNCaP cells and exhibited ∼ 5 times more selective binding for ER-β than ER-α, in comparison to raloxifene. DIMA exhibited a dose-dependent ER-β agonism and ER-α antagonism in classical gene reporter assay and decreased hTERT (catalytic subunit of telomerase) transcript levels in LNCaP at 3.0 μM (P < 0.05). DIMA also dose-dependently decreased telomerase enzyme activity in prostate cancer cells. It is thus concluded that DIMA acts as a multi-steroid receptor modulator and effectively inhibits proliferation of prostate cancer cells through ER-β mediated telomerase inhibition, by countering actions of ER-α and AR. Its unique molecular design can serve as a lead structure for generation of potent agents against endocrine malignancies like the CaP

  10. Functional requirement of p23 and Hsp90 in telomerase complexes

    OpenAIRE

    Holt, Shawn E.; Aisner, Dara L.; Baur, Joseph; Tesmer, Valerie M.; Dy, Marife; Ouellette, Michel; Trager, James B.; Morin, Gregg B.; Toft, David O.; Jerry W Shay; Wright, Woodring E.; White, Michael A.

    1999-01-01

    Most normal human diploid cells have no detectable telomerase; however, expression of the catalytic subunit of telomerase is sufficient to induce telomerase activity and, in many cases, will bypass normal senescence. We and others have previously demonstrated in vitro assembly of active telomerase by combining the purified RNA component with the reverse transcriptase catalytic component synthesized in rabbit reticulocyte extract. Here we show that assembly of active telomerase from in vitro-s...

  11. Disease mutant analysis identifies a new function of DAXX in telomerase regulation and telomere maintenance

    OpenAIRE

    Tang, Mengfan; Li, Yujing; Zhang, Yi; Chen, Yuxi; Huang, Wenjun; Wang, Dan; Zaug, Arthur J.; Liu, Dan; Zhao, Yong; Cech, Thomas R.; Ma, Wenbin; Songyang, Zhou

    2015-01-01

    Most human cancers depend on the telomerase to maintain telomeres; however, about 10% of cancers are telomerase negative and utilize the alternative lengthening of telomeres (ALT) mechanism. Mutations in the DAXX gene have been found frequently in both telomerase-positive and ALT cells, and how DAXX mutations contribute to cancers remains unclear. We report here that endogenous DAXX can localize to Cajal bodies, associate with the telomerase and regulate telomerase targeting to telomeres. Fur...

  12. New prospects for targeting telomerase beyond the telomere.

    Science.gov (United States)

    Arndt, Greg M; MacKenzie, Karen L

    2016-08-01

    Telomerase activity is responsible for the maintenance of chromosome end structures (telomeres) and cancer cell immortality in most human malignancies, making telomerase an attractive therapeutic target. The rationale for targeting components of the telomerase holoenzyme has been strengthened by accumulating evidence indicating that these molecules have extra-telomeric functions in tumour cell survival and proliferation. This Review discusses current knowledge of the biogenesis, structure and multiple functions of telomerase-associated molecules intertwined with recent advances in drug discovery approaches. We also describe the fertile ground available for the pursuit of next-generation small-molecule inhibitors of telomerase. PMID:27339602

  13. Tumor therapy targeting human telomerase reverse transcriptase%以人端粒酶逆转录酶为靶点的肿瘤治疗

    Institute of Scientific and Technical Information of China (English)

    陈晨; 王燕; 陈始明; 陶泽璋

    2008-01-01

    Human telomerase reverse transcriptase (hTERT) is one of the focus researches of cancer therapy in recent years,including the studies of human telomerase inhibitor, RNA interfere targeting hTERT and gene therapy research, as well as hTERT-mediated immunology research. All these studies have gotten some a-chievements.%人端粒酶逆转录酶是近几年肿瘤治疗研究的一个热点,包括端粒酶活性抑制剂研究、以人端粒酶逆转录酶为靶点的RNA干扰研究、人端粒酶逆转录酶介导的免疫学研究以及以人端粒酶逆转录酶为靶点的基因治疗研究等,并取得了一定的成果.

  14. The GG Genotype of Telomerase Reverse Transcriptase at Genetic Locus rs2736100 Is Associated with Human Atherosclerosis Risk in the Han Chinese Population

    OpenAIRE

    Feng, Lei; Nian, Shi-yan; Zhang, Jihong

    2014-01-01

    A single nucleotide polymorphism (SNP) in the second intron of human TERT (hTERT), rs2736100, acts as a critical factor in hTERT synthesis and activation. The rs2736100 SNP was found to be associated with susceptibility to many cancers. Recently, inhibition of telomerase and marked telomere shortening were determined to be closely associated with the increasing severity of atherosclerosis. The association between the SNP of rs2736100 and the presence of atherosclerosis was evaluated in 84 ath...

  15. Modulation of Telomeres in Alternative Lengthening of Telomeres Type I Like Human Cells by the Expression of Werner Protein and Telomerase

    OpenAIRE

    Aisha Siddiqa; David Cavazos; Jeffery Chavez; Linda Long; Marciniak, Robert A.

    2012-01-01

    The alternative lengthening of telomeres (ALT) is a recombination-based mechanism of telomere maintenance activated in 5–20% of human cancers. In Saccharomyces cerevisiae, survivors that arise after inactivation of telomerase can be classified as type I or type II ALT. In type I, telomeres have a tandem array structure, with each subunit consisting of a subtelomeric Y′ element and short telomere sequence. Telomeres in type II have only long telomere repeats and require Sgs1, the S. cerevisiae...

  16. Maintenance of differentiation potential of human bone marrow mesenchymal stem cells immortalized by human telomerase reverse transcriptase gene despite of extensive proliferation

    International Nuclear Information System (INIS)

    Human bone marrow mesenchymal stem cells (hMSC) represent a population of stem cells that are capable of differentiation into multiple lineages. However, these cells exhibit senescence-associated growth arrest and phenotypic changes during long-term in vitro culture. We have recently demonstrated that overexpression of human telomerase reverse transcriptase (hTERT) in hMSC reconstitutes telomerase activity and extends life span of the cells [Nat. Biotechnol. 20 (2002) 592]. In the present study, we have performed extensive characterization of three independent cell lines derived from the parental hMSC-TERT cell line based on different plating densities during expansion in culture: 1:2 (hMSC-TERT2), 1:4 (hMSC-TERT4), and 1:20 (hMSC-TERT20). The 3 cell lines exhibited differences in morphology and growth rates but they all maintained the characteristics of self-renewing stem cells and the ability to differentiate into multiple mesoderm-type cell lineages: osteoblasts, adipocytes, chondrocytes, and endothelial-like cells over a 3-year period in culture. Also, surface marker studies using flow cytometry showed a pattern similar to that known from normal hMSC. Thus, telomerization of hMSC by hTERT overexpression maintains the stem cell phenotype of hMSC and it may be a useful tool for obtaining enough number of cells with a stable phenotype for mechanistic studies of cell differentiation and for tissue engineering protocols

  17. Methods of Telomerase Inhibition

    OpenAIRE

    Andrews, Lucy G.; Tollefsbol, Trygve O.

    2008-01-01

    Telomerase is central to cellular immortality and is a key component of most cancer cells although this enzyme is rarely expressed to significant levels in normal cells. Therefore, the inhibition of telomerase has garnered considerable attention as a possible anticancer approach. Many of the methods applied to telomerase inhibition focus on either of the two major components of the ribonucleoprotein holoenzyme, that is, the telomerase reverse transcriptase (TERT) catalytic subunit or the telo...

  18. Retroviral insertional mutagenesis in telomerase-immortalized hepatocytes identifies RIPK4 as novel tumor suppressor in human hepatocarcinogenesis.

    Science.gov (United States)

    Heim, D; Cornils, K; Schulze, K; Fehse, B; Lohse, A W; Brümmendorf, T H; Wege, H

    2015-01-15

    Carcinogenesis is a multistep process involving alterations in various cellular pathways. The critical genetic events driving the evolution of primary liver cancer, specifically hepatoblastoma and hepatocellular carcinoma (HCC), are still poorly understood. However, telomere stabilization is acknowledged as prerequisite for cancer progression in humans. In this project, human fetal hepatocytes were utilized as a cell culture model for untransformed, proliferating human liver cells, with telomerase activation as first oncogenic hit. To elucidate critical downstream genetic events driving further transformation of immortalized liver cells, we used retroviral insertional mutagenesis as an unbiased approach to induce genetic alterations. Following isolation of hyperproliferating, provirus-bearing cell clones, we monitored cancer-associated growth properties and characterized changes toward a malignant phenotype. Three transformed clones with the ability to form colonies in soft agar were expanded. As proof-of-principle for our experimental setup, we identified a transforming insertion on chromosome 8 within the pleiomorphic adenoma gene 1 (PLAG1), resulting in a 20-fold increase in PLAG1 expression. Upregulation of PLAG1 has already been described to promote human hepatoblastoma development. In a separate clone, a transforming insertion was detected in close proximity to the receptor-interacting serine-threonine kinase 4 (RIPK4) with an approximately eightfold suppression in RIPK4 expression. As validation for this currently unknown driver in hepatocarcinogenesis, we examined RIPK4 expression in human HCC samples and confirmed a significant suppression of RIPK4 in 80% of the samples. Furthermore, overexpression of RIPK4 in transformed human fetal hepatocytes resulted in an almost complete elimination of anchorage-independent growth. On the basis of these data, we propose RIPK4 as a novel putative tumor suppressor in human hepatocarcinogenesis. PMID:24413083

  19. Telomerase:a novel target of antitumor agents

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Telomerase activity was found to be high in various human cancers, but absent in most normal tissues. Its expression pattern made it a novel target for antitumor agents. Several strategies against telomerase were presented in this review. Targeting the telomerase RNA component by oligonucleotide/ribozyme was considered to be one of the most hopeful approaches. Some progresses were made in this area, such as the use of PANs and 2- 5A antisense compounds. The relationships among telomerase activity and cell differentiation, signal transduction, oncogene, tumor suppressor gene as well as cell cycle modulation also provided a series of valuable ideas in designing anti-telomerase drugs for cancer therapy. In conclusion, although there is still a long way in understanding the mechanism and regulation of telomerase, the advance of studies on telomerase has allowed the development of numerous strategies for the treatment of cancer.

  20. Expression of human telomerase reverse transcriptase protein in oral epithelial dysplasia and oral squamous cell carcinoma: An immunohistochemical study

    OpenAIRE

    Bangalore Nagarajachar Raghunandan; Karpagaselvi Sanjai; Jayalakshmi Kumaraswamy; Lokesh Papaiah; Bhavna Pandey; Bellur MadhavaRao Jyothi

    2016-01-01

    Background: Telomerase is an RNA-dependent DNA polymerase that synthesizes TTAGGG telomeric DNA sequences and almost universally provides the molecular basis for unlimited proliferative potential. The telomeres become shorter with each cycle of replication and reach a critical limit; most cells die or enter stage of replicative senescence. Telomere length maintenance by telomerase is required for all the cells that exhibit limitless replicative potential. It has been postulated that reactivat...

  1. Antisense epidermal growth factor receptor RNA transfection in human glioblastoma cells down-regulates telomerase activity and telomere length

    OpenAIRE

    Tian, X-X; Pang, JC-S; J. Zheng; Chen, J; To, S S T; Ng, H-K

    2002-01-01

    Epidermal growth factor receptor is overexpressed and/or amplified in up to 50% of glioblastomas, suggesting an important role of this gene in glial tumorigenesis and progression. In the present study we demonstrated that epidermal growth factor receptor is involved in regulation of telomerase activity in glioblastoma. Antisense-epidermal growth factor receptor approach was used to inhibit epidermal growth factor receptor expression of glioblastoma U87MG cells. Telomerase activity in antisens...

  2. Testicular expression of survivin and human telomerase reverse transcriptase (hTERT) associated with spermatogenic function in infertile patients

    Institute of Scientific and Technical Information of China (English)

    Steffen Weikert; Frank Christoph; Wolfgang Schulze; Hans Krause; Carsten Kempkensteffen; Martin Schostak; Kurt Miller; Mark Schrader

    2006-01-01

    Aim: To characterize the coexpression of survivin, an inhibitor of apoptosis (IAF), and human telomerase reverse transcriptase (hTERT) in human testes with varying spermatogenic function. Methods: Transcript levels of survivin mRNA and hTERT mRNA were determined in normal testes (n = 11) and testes with defective spermatogenesis (n = 28) using real-time reverse-transcription polymerase chain reaction (RT-PCR). The histological work-up was performed according to a modified Johnsen score. Results: Expressions of both survivin and hTERT were highest at median levels of 96.8 and 709 in normal spermatogenesis and dropped to 53.3 and 534 in testes with postmeiotic spermatogenic arrest (n = 10). In severe spermatogenic failure (n = 18), survivin expression was lacking in most specimens (n = 16), whereas at least low levels of testicular hTERT expression were largely detectable with a normalized expression of 73 in premeiotic spermatogenic arrest (n = 7) and 45 in patients with Sertoli cell-only syndrome (SCOS)(n = 3). Both survivin and hTERT expressions increased with a progressing Johnsen score (P for trend = 0.001).Conclusion: Although both survivin and hTERT are correlated with spermatogenic function, they show different expression patterns in testes of infertile patients. These findings substantiate results from studies in the rodent testis suggesting a predominant expression of survivin in meiotically dividing germ cells.

  3. Telomerase activity in pregnancy complications (Review).

    Science.gov (United States)

    Fragkiadaki, Persefoni; Tsoukalas, Dimitrios; Fragkiadoulaki, Irini; Psycharakis, Christos; Nikitovic, Dragana; Spandidos, Demetrios A; Tsatsakis, Aristides M

    2016-07-01

    Telomeres are specific DNA regions positioned at the ends of chromosomes and composed of functional non-coding repeats. Upon cell division, the telomeres decrease in length by a preordained amount. When the telomeres become critically short, cells lose the ability to divide and enter a specific functioning mode designated as 'cellular senescence'. However, human tissues express an enzyme that deters the shrinking of the telomeres, the telomerase. Due to its ability to maintain telomere length, the telomerase slows down and possibly suspends the aging of the cells. In regard to this, solid evidence demonstrates that female human fertility decreases with increased maternal age and that various adverse factors, including alterations in telomerase activity, can contribute to age-associated infertility in women. The fact that telomerase activity is regulated in a time- and location-dependent manner in both embryo and placental tissues, highlights it potential importance to the successful completion of pregnancy. Since maternal age is a crucial determining factor for the success of in vitro and in vivo fertilization, numerous studies have focused on telomerase activity and its correlation with mammalian fertilization, as well as the following cleavage and pre-implantation developmental processes. Associations between telomerase activity and pregnancy complications have been previously observed. Our aim in this review was to summarize and critically discuss evidence correlating telomerase activity with pregnancy complications. PMID:27175856

  4. Telomerase activity in pregnancy complications (Review)

    Science.gov (United States)

    FRAGKIADAKI, PERSEFONI; TSOUKALAS, DIMITRIOS; FRAGKIADOULAKI, IRINI; PSYCHARAKIS, CHRISTOS; NIKITOVIC, DRAGANA; SPANDIDOS, DEMETRIOS A.; TSATSAKIS, ARISTIDES M.

    2016-01-01

    Telomeres are specific DNA regions positioned at the ends of chromosomes and composed of functional non-coding repeats. Upon cell division, the telomeres decrease in length by a preordained amount. When the telomeres become critically short, cells lose the ability to divide and enter a specific functioning mode designated as 'cellular senescence'. However, human tissues express an enzyme that deters the shrinking of the telomeres, the telomerase. Due to its ability to maintain telomere length, the telomerase slows down and possibly suspends the aging of the cells. In regard to this, solid evidence demonstrates that female human fertility decreases with increased maternal age and that various adverse factors, including alterations in telomerase activity, can contribute to age-associated infertility in women. The fact that telomerase activity is regulated in a time- and location-dependent manner in both embryo and placental tissues, highlights it potential importance to the successful completion of pregnancy. Since maternal age is a crucial determining factor for the success of in vitro and in vivo fertilization, numerous studies have focused on telomerase activity and its correlation with mammalian fertilization, as well as the following cleavage and pre-implantation developmental processes. Associations between telomerase activity and pregnancy complications have been previously observed. Our aim in this review was to summarize and critically discuss evidence correlating telomerase activity with pregnancy complications. PMID:27175856

  5. Molecular Detection of Human Telomerase mRNA (hTERT-mRNA in Egyptian Patients with Hepatocellular Carcinoma

    Directory of Open Access Journals (Sweden)

    Gahan Kamal El-Saeed

    2009-06-01

    Full Text Available Background and Aims: Diagnostic modalities for hepatocellular carcinoma (HCC as markers, sonography, and CT have contributed to the early detection of HCC but are still not sensitive enough. Human telomerase RNA subunit (hTERT-mRNA has been identified in many cancers and claimed to be reactivated in HCC. To investigate hTERT-mRNA in the peripheral blood of HCC and chronic liver disease (CLD patients and correlate its level with alpha feto protein (AFP, the serological marker for HCC.Methods: The study was conducted on 44 patients selected from the National Liver Institute. Patients included Group I (22 patients diagnosed to have HCC, Group II (22 patients with CLD, and 12 apparently healthy volunteers as controls (Group III. All selected individuals were subjected to history taking, a clinical examination, abdominal sonography and laboratory investigations as liver function tests (LFTs, cell blood count (CBC, hepatitis viral markers, AFP, and real-time polymerase chain reaction (PCR Quantitative detection of -mRNA expression, encoding for telomerase catalytic subunit.Results: There was a significant elevation of AFP levels in the HCC group compared to both the CLD and control groups (P < 0.00, P < 0.001. The mean hTERT-mRNA expression in HCC patients was significantly higher than both CLD patients and controls (P < 0.001, P < 0.001. hTERT-mRNA was correlated with AFP and tumor size (P < 0.05, P < 0.001. The AFP cutoff level (185 ng/ml resulted in a 63.6% sensitivity, a 85.3% specificity; a 89.3% positive predictive value (PPV level, a 76.2 % negative predictive value (NPV level and a 83.4% accuracy for HCC prediction. The hTERT-mRNA cutoff level (112.5 copies/ml showed a 77.3% sensitivity, a 97.1% specificity, a 98% PPV level, a 79.2 % NPV level, and an accuracy of 84% for HCC prediction. Combining hTERT-mRNA and AFP increased diagnostic accuracy to 90.5%. Both markers had a 84.1% sensitivity, a 86.4% specificity, a 86.4% PPV level, and a 88

  6. Ectopically hTERT expressing adult human mesenchymal stem cells are less radiosensitive than their telomerase negative counterpart

    International Nuclear Information System (INIS)

    During the past several years increasing evidence indicating that the proliferation capacity of mammalian cells is highly radiosensitive, regardless of the species and the tissue of origin of the cells, has accumulated. It has also been shown that normal bone marrow cells of mice have a similar radiosensitivity to other mammalian cells so far tested. In this study, we investigated the genetic effects of ionizing radiation (2.5-15 Gy) on normal human mesenchymal stem cells and their telomerised counterpart hMSC-telo1. We evaluated overall genomic integrity, DNA damage/repair by applying a fluorescence-detected alkaline DNA unwinding assay together with Western blot analyses for phosphorylated H2AX and Q-FISH was applied for investigation of telomeric damage. Our results indicate that hMSC and TERT-immortalized hMSCs can cope with relatively high doses of γ-rays and that overall DNA repair is similar in the two cell lines. The telomeres were extensively destroyed after irradiation in both cell types suggesting that telomere caps are especially sensitive to radiation. The TERT-immortalized hMSCs showed higher stability at telomeric regions than primary hMSCs indicating that cells with long telomeres and high telomerase activity have the advantage of re-establishing the telomeric caps

  7. Immunological features of T cells induced by human telomerase reverse transcriptase-derived peptides in patients with hepatocellular carcinoma.

    Science.gov (United States)

    Mizukoshi, Eishiro; Nakagawa, Hidetoshi; Kitahara, Masaaki; Yamashita, Tatsuya; Arai, Kuniaki; Sunagozaka, Hajime; Fushimi, Kazumi; Kobayashi, Eiji; Kishi, Hiroyuki; Muraguchi, Atsushi; Kaneko, Shuichi

    2015-08-10

    Human telomerase reverse transcriptase (hTERT) is a catalytic enzyme required for telomere elongation. In this study, we investigated the safety and immunogenicity of an hTERT-derived peptide (hTERT461) as a vaccine and characterized the hTERT-specific T cell responses induced. Fourteen hepatocellular carcinoma (HCC) patients were enrolled in the study. The hTERT-derived peptide was emulsified in incomplete Freund's adjuvant and administered via subcutaneous immunization three times biweekly. The maximum toxicity observed was grade 2 according to the common terminology criteria and mainly consisted of skin reactions at the site of vaccination. The vaccination induced hTERT-specific immunity in 71.4% of patients and 57.1% of patients administered with hTERT461 peptide-specific T cells could prevent HCC recurrence after vaccination. In phenotypic analysis, the post-vaccinated increase in hTERT-specific T cells was due to an increase in cells with the effector memory phenotype, with the potential to produce multiple cytokines. Seven hTERT-specific T cell receptors were obtained from the vaccinated patients, showing their cytotoxic activities to hTERT-derived peptide-bearing cells. In conclusion, the safety and effects of immune boosting by hTERT461 peptide have shown the potential of the peptide to provide clinical benefits in HCC patients. PMID:25982205

  8. Premature aging in telomerase-deficient zebrafish

    Directory of Open Access Journals (Sweden)

    Monique Anchelin

    2013-09-01

    The study of telomere biology is crucial to the understanding of aging and cancer. In the pursuit of greater knowledge in the field of human telomere biology, the mouse has been used extensively as a model. However, there are fundamental differences between mouse and human cells. Therefore, additional models are required. In light of this, we have characterized telomerase-deficient zebrafish (Danio rerio as the second vertebrate model for human telomerase-driven diseases. We found that telomerase-deficient zebrafish show p53-dependent premature aging and reduced lifespan in the first generation, as occurs in humans but not in mice, probably reflecting the similar telomere length in fish and humans. Among these aging symptoms, spinal curvature, liver and retina degeneration, and infertility were the most remarkable. Although the second-generation embryos died in early developmental stages, restoration of telomerase activity rescued telomere length and survival, indicating that telomerase dosage is crucial. Importantly, this model also reproduces the disease anticipation observed in humans with dyskeratosis congenita (DC. Thus, telomerase haploinsufficiency leads to anticipation phenomenon in longevity, which is related to telomere shortening and, specifically, with the proportion of short telomeres. Furthermore, p53 was induced by telomere attrition, leading to growth arrest and apoptosis. Importantly, genetic inhibition of p53 rescued the adverse effects of telomere loss, indicating that the molecular mechanisms induced by telomere shortening are conserved from fish to mammals. The partial rescue of telomere length and longevity by restoration of telomerase activity, together with the feasibility of the zebrafish for high-throughput chemical screening, both point to the usefulness of this model for the discovery of new drugs able to reactivate telomerase in individuals with DC.

  9. Involvement of transcription repressor Snail in the regulation of human telomerase reverse transcriptase (hTERT) by transforming growth factor-β.

    Science.gov (United States)

    Yoo, Young-Sun; Park, Seoyoung; Gwak, Jungsug; Ju, Bong Gun; Oh, Sangtaek

    2015-09-11

    Human telomerase reverse transcriptase (hTERT), a catalytic subunit of telomerase, is the primary determinant for telomerase enzyme activity, which has been associated with cellular immortality. Expression of the hTERT gene is regulated by various extracellular (external) stimuli and is aberrantly up-regulated in more than 90% of cancers. Here we show that hTERT gene expression was repressed in response to transforming growth factor-β (TGF-β) by a mechanism dependent on transcription factors Snail and c-Myc. TGF-β activated Snail and down-regulated c-Myc gene expression. In addition, ectopic expression of Snail strongly inhibited hTERT promoter activity, although co-expression of c-Myc abrogated this effect. Chromatin immunoprecipitation (ChIP) analysis revealed that TGF-β decreased c-Myc occupancy and dramatically increased recruitment of Snail to the E-box motifs of the hTERT promoter, thereby repressing hTERT expression. Our findings suggest a dynamic alteration in hTERT promoter occupancy by Snail and c-Myc is the mechanistic basis for TGF-β-mediated regulation of hTERT. PMID:26235880

  10. Inhibition of telomerase in tumor cells by ribozyme targeting telomerase RNA component

    Institute of Scientific and Technical Information of China (English)

    LIU; Bailin(刘柏林); QU; Yi(屈艺); LIU; Shuqiu(刘菽秋); OUYANG; Xuesong(欧阳雪松)

    2002-01-01

    Telomerase plays an important role in cell proliferation and carcinogenesis and is believed to be a good target for anti-cancer drugs. Elimination of template function of telomerase RNA may repress the telomerase activity. A hammer-headed ribozyme(telomerase ribozyme, teloRZ) directed against the RNA component of human telomerase(hTR) was designed and synthesized. TeloRZ showed a specific cleavage activity against the hTR. The cleavage efficacy reached 60%. A eukaryotic expression plasmid containing teloRZ gene was inducted into HeLa cells by lipofectamine, the telomerase activity in HeLa cells expressing teloRZ decreased to one eighth of that in the control cells. The doubling time increased significantly and the apoptosis ratio was elevated with increasing population doublings(PDS). After 19-20 PDS 95% cells were apoptotic. To further investigate the effect of teloRZ on tumor growth, the eukaryotic expression plasmid containing teloRZ was injected into transplanted tumor of nude mouse. The teloRZ effectively inhibited the telomerase activity in transplanted tumor, promoted apoptosis of the transplanted tumor cells, and decreased the tumor size significantly. These results indicate that teloRZ can effectively inhibit telomerase activity and growth of tumor cells, and suggest the potential use of this ribozyme in anti-cancer therapy.

  11. Roles of telomeres and telomerase in cancer, and advances in telomerase-targeted therapies.

    Science.gov (United States)

    Jafri, Mohammad A; Ansari, Shakeel A; Alqahtani, Mohammed H; Shay, Jerry W

    2016-01-01

    Telomeres maintain genomic integrity in normal cells, and their progressive shortening during successive cell divisions induces chromosomal instability. In the large majority of cancer cells, telomere length is maintained by telomerase. Thus, telomere length and telomerase activity are crucial for cancer initiation and the survival of tumors. Several pathways that regulate telomere length have been identified, and genome-scale studies have helped in mapping genes that are involved in telomere length control. Additionally, genomic screening for recurrent human telomerase gene hTERT promoter mutations and mutations in genes involved in the alternative lengthening of telomeres pathway, such as ATRX and DAXX, has elucidated how these genomic changes contribute to the activation of telomere maintenance mechanisms in cancer cells. Attempts have also been made to develop telomere length- and telomerase-based diagnostic tools and anticancer therapeutics. Recent efforts have revealed key aspects of telomerase assembly, intracellular trafficking and recruitment to telomeres for completing DNA synthesis, which may provide novel targets for the development of anticancer agents. Here, we summarize telomere organization and function and its role in oncogenesis. We also highlight genomic mutations that lead to reactivation of telomerase, and mechanisms of telomerase reconstitution and trafficking that shed light on its function in cancer initiation and tumor development. Additionally, recent advances in the clinical development of telomerase inhibitors, as well as potential novel targets, will be summarized. PMID:27323951

  12. Curcumin Regulates Low-Linear Energy Transfer γ-Radiation-Induced NFκB-Dependent Telomerase Activity in Human Neuroblastoma Cells

    International Nuclear Information System (INIS)

    Purpose: We recently reported that curcumin attenuates ionizing radiation (IR)-induced survival signaling and proliferation in human neuroblastoma cells. Also, in the endothelial system, we have demonstrated that NFκB regulates IR-induced telomerase activity (TA). Accordingly, we investigated the effect of curcumin in inhibiting IR-induced NFκB-dependent hTERT transcription, TA, and cell survival in neuroblastoma cells. Methods and Materials: SK-N-MC or SH-SY5Y cells exposed to IR and treated with curcumin (10-100 nM) with or without IR were harvested after 1 h through 24 h. NFκB-dependent regulation was investigated either by luciferase reporter assays using pNFκB-, pGL3-354-, pGL3-347-, or pUSE-IκBα-Luc, p50/p65, or RelA siRNA-transfected cells. NFκB activity was analyzed using an electrophoretic mobility shift assay and hTERT expression using the quantitative polymerase chain reaction. TA was determined using the telomerase repeat amplification protocol assay and cell survival using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltertrazolium bromide and clonogenic assay. Results: Curcumin profoundly inhibited IR-induced NFκB. Consequently, curcumin significantly inhibited IR-induced TA and hTERT mRNA at all points investigated. Furthermore, IR-induced TA is regulated at the transcriptional level by triggering telomerase reverse transcriptase (TERT) promoter activation. Moreover, NFκB becomes functionally activated after IR and mediates TA upregulation by binding to the κB-binding region in the promoter region of the TERT gene. Consistently, elimination of the NFκB-recognition site on the telomerase promoter or inhibition of NFκB by the IκBα mutant compromises IR-induced telomerase promoter activation. Significantly, curcumin inhibited IR-induced TERT transcription. Consequently, curcumin inhibited hTERT mRNA and TA in NFκB overexpressed cells. Furthermore, curcumin enhanced the IR-induced inhibition of cell survival. Conclusions: These results

  13. Evaluation of telomerase expression in chronic periodontitis

    OpenAIRE

    Balaji T; Vettriselvi V; Paul Solomon; Rao Suresh

    2010-01-01

    Background : Human telomerase is a multi subunit ribonucleoprotein enzyme concerned with telomeric lengthening and homeostasis in man. This enzyme has been found to be elevated in inflammatory conditions like rheumatoid arthritis and silica injury lung. Since chronic periodontitis is also an inflammatory condition where immune cells and cytokines mediate tissue destruction, we set out to evaluate telomerase in gingival tissue samples from healthy subjects and chronic periodontitis patients by...

  14. Functional interaction between telomere protein TPP1 and telomerase

    OpenAIRE

    Zaug, Arthur J.; Podell, Elaine R.; Nandakumar, Jayakrishnan; Cech, Thomas R.

    2010-01-01

    Human chromosome end-capping and telomerase regulation require POT1 (Protection of Telomeres 1) and TPP1 proteins, which bind to the 3′ ssDNA extension of human telomeres. POT1–TPP1 binding to telomeric DNA activates telomerase repeat addition processivity. We now provide evidence that this POT1–TPP1 activation requires specific interactions with telomerase, rather than it being a DNA substrate-specific effect. First, telomerase from the fish medaka, which extends the same telomeric DNA prime...

  15. Expression of Telomerase Subunits in Gastric Cancer

    Institute of Scientific and Technical Information of China (English)

    CHEN Fenghua; HU Lihua; LI Yirong; WANG Lin

    2005-01-01

    To detect the expression of telomerase subunits human telomerase reverse transcriptase, human telomerase associated protein 1 and human telomerase RNA) in gastric cancer and to examine the role that different telomerase subunits play in the gastric carcinogenesis, reverse transcription-polymerase chain reaction (RT-PCR) was used to detect telomerase subunits messenger RNA in 24 samples of gastric cancer and corresponding non-cancerous tissue. The results showed that the positive rate of hTERT mRNA from gastric cancer and corresponding non-cancerous tissues was 100 % and 25 %, respectively. The former was significantly higher than the latter (χ2 =26.4, P<0.01). The positive rate of hTEP1 mRNA from gastric cancer and corresponding non-cancerous tissues was 100 % and 91.7 %, respectively and no significant difference was found between them (χ2 =2.1, P>0.05). The positive rates of hTR for gastric cancer and corresponding non-cancerous tissues were both 100 % and no significant difference existed between them. It is concluded that in contrast to hTEP1 and hTR, the up-regulation of hTERT mRNA expression may play a more important role in the development of gastric cancer.

  16. Nutrition and lifestyle in healthy aging: the telomerase challenge.

    Science.gov (United States)

    Boccardi, Virginia; Paolisso, Giuseppe; Mecocci, Patrizia

    2016-01-01

    Nutrition and lifestyle, known to modulate aging process and age-related diseases, might also affect telomerase activity. Short and dysfunctional telomeres rather than average telomere length are associated with longevity in animal models, and their rescue by telomerase maybe sufficient to restore cell and organismal viability. Improving telomerase activation in stem cells and potentially in other cells by diet and lifestyle interventions may represent an intriguing way to promote health-span in humans. PMID:26826704

  17. Telomerase Repeated Amplification Protocol (TRAP)

    Science.gov (United States)

    Mender, Ilgen; Shay, Jerry W.

    2016-01-01

    Telomeres are found at the end of eukaryotic linear chromosomes, and proteins that bind to telomeres protect DNA from being recognized as double-strand breaks thus preventing end-to-end fusions (Griffith et al., 1999). However, due to the end replication problem and other factors such as oxidative damage, the limited life span of cultured cells (Hayflick limit) results in progressive shortening of these protective structures (Hayflick and Moorhead, 1961; Olovnikov, 1973). The ribonucleoprotein enzyme complex telomerase-consisting of a protein catalytic component hTERT and a functional RNA component hTR or hTERC- counteracts telomere shortening by adding telomeric repeats to the end of chromosomes in ~90% of primary human tumors and in some transiently proliferating stem-like cells (Shay and Wright, 1996; Shay and Wright, 2001). This results in continuous proliferation of cells which is a hallmark of cancer. Therefore, telomere biology has a central role in aging, cancer progression/metastasis as well as targeted cancer therapies. There are commonly used methods in telomere biology such as Telomere Restriction Fragment (TRF) (Mender and Shay, 2015b), Telomere Repeat Amplification Protocol (TRAP) and Telomere dysfunction Induced Foci (TIF) analysis (Mender and Shay, 2015a). In this detailed protocol we describe Telomere Repeat Amplification Protocol (TRAP). The TRAP assay is a popular method to determine telomerase activity in mammalian cells and tissue samples (Kim et al., 1994). The TRAP assay includes three steps: extension, amplification, and detection of telomerase products. In the extension step, telomeric repeats are added to the telomerase substrate (which is actually a non telomeric oligonucleotide, TS) by telomerase. In the amplification step, the extension products are amplified by the polymerase chain reaction (PCR) using specific primers (TS upstream primer and ACX downstream primer) and in the detection step, the presence or absence of telomerase is

  18. Ectopically hTERT expressing adult human mesenchymal stem cells are less radiosensitive than their telomerase negative counterpart

    DEFF Research Database (Denmark)

    Serakinci, Nedime; Christensen, Rikke; Graakjaer, Jesper;

    2007-01-01

    During the past several years increasing evidence indicating that the proliferation capacity of mammalian cells is highly radiosensitive, regardless of the species and the tissue of origin of the cells, has accumulated. It has also been shown that normal bone marrow cells of mice have a similar r...... high telomerase activity have the advantage of re-establishing the telomeric caps...

  19. Modulation of Telomeres in Alternative Lengthening of Telomeres Type I Like Human Cells by the Expression of Werner Protein and Telomerase

    Directory of Open Access Journals (Sweden)

    Aisha Siddiqa

    2012-01-01

    Full Text Available The alternative lengthening of telomeres (ALT is a recombination-based mechanism of telomere maintenance activated in 5–20% of human cancers. In Saccharomyces cerevisiae, survivors that arise after inactivation of telomerase can be classified as type I or type II ALT. In type I, telomeres have a tandem array structure, with each subunit consisting of a subtelomeric Y′ element and short telomere sequence. Telomeres in type II have only long telomere repeats and require Sgs1, the S. cerevisiae RecQ family helicase. We previously described the first human ALT cell line, AG11395, that has a telomere structure similar to type I ALT yeast cells. This cell line lacks the activity of the Werner syndrome protein, a human RecQ helicase. The telomeres in this cell line consist of tandem repeats containing SV40 DNA, including the origin of replication, and telomere sequence. We investigated the role of the SV40 origin of replication and the effects of Werner protein and telomerase on telomere structure and maintenance in AG11395 cells. We report that the expression of Werner protein facilitates the transition in human cells of ALT type I like telomeres to type II like telomeres in some aspects. These findings have implications for the diagnosis and treatment of cancer.

  20. Interferon-inducible IFI16, a negative regulator of cell growth, down-regulates expression of human telomerase reverse transcriptase (hTERT gene.

    Directory of Open Access Journals (Sweden)

    Lynda Li Song

    Full Text Available BACKGROUND: Increased levels of interferon (IFN-inducible IFI16 protein (encoded by the IFI16 gene located at 1q22 in human normal prostate epithelial cells and diploid fibroblasts (HDFs are associated with the onset of cellular senescence. However, the molecular mechanisms by which the IFI16 protein contributes to cellular senescence-associated cell growth arrest remain to be elucidated. Here, we report that increased levels of IFI16 protein in normal HDFs and in HeLa cells negatively regulate the expression of human telomerase reverse transcriptase (hTERT gene. METHODOLOGY/PRINCIPAL FINDINGS: We optimized conditions for real-time PCR, immunoblotting, and telomere repeat amplification protocol (TRAP assays to detect relatively low levels of hTERT mRNA, protein, and telomerase activity that are found in HDFs. Using the optimized conditions, we report that treatment of HDFs with inhibitors of cell cycle progression, such as aphidicolin or CGK1026, which resulted in reduced steady-state levels of IFI16 mRNA and protein, was associated with increases in hTERT mRNA and protein levels and telomerase activity. In contrast, knockdown of IFI16 expression in cells increased the expression of c-Myc, a positive regulator of hTERT expression. Additionally, over-expression of IFI16 protein in cells inhibited the c-Myc-mediated stimulation of the activity of hTERT-luc-reporter and reduced the steady-state levels of c-Myc and hTERT. CONCLUSIONS/SIGNIFICANCE: These data demonstrated that increased levels of IFI16 protein in HDFs down-regulate the expression of hTERT gene. Our observations will serve basis to understand how increased cellular levels of the IFI16 protein may contribute to certain aging-dependent diseases.

  1. The Ku subunit of telomerase binds Sir4 to recruit telomerase to lengthen telomeres in S. cerevisiae.

    Science.gov (United States)

    Hass, Evan P; Zappulla, David C

    2015-01-01

    In Saccharomyces cerevisiae and in humans, the telomerase RNA subunit is bound by Ku, a ring-shaped protein heterodimer best known for its function in DNA repair. Ku binding to yeast telomerase RNA promotes telomere lengthening and telomerase recruitment to telomeres, but how this is achieved remains unknown. Using telomere-length analysis and chromatin immunoprecipitation, we show that Sir4 - a previously identified Ku-binding protein that is a component of telomeric silent chromatin - is required for Ku-mediated telomere lengthening and telomerase recruitment. We also find that specifically tethering Sir4 directly to Ku-binding-defective telomerase RNA restores otherwise-shortened telomeres to wild-type length. These findings suggest that Sir4 is the telomere-bound target of Ku-mediated telomerase recruitment and provide one mechanism for how the Sir4-competing Rif1 and Rif2 proteins negatively regulate telomere length in yeast. PMID:26218225

  2. Study on the Detection of Telomerase Activity by Combining DNA Sequence Analysis with TRAP

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Telomeric repeat amplification protocol (TRAP) is now aconventional assay for detecting telomerase activity. However, this method presents problems owing to tedious quantitation, radioisotopic handling. In order to alleviate these inconveniences, a novel telomerase DNA sequencing assay together with TRAP to detect human telomerase activity was developed. It was used to detect telomerase activity in Hela, HLF, MCF, K562, SMMC-7721 cells, Leukocytes and RNase-pretreated or heat-treated cells as control. Telomerase activity assayed by this method was positive when the number of K562 cells examined was 102,103, and 104. The telomerase activity depended on the number of K562 cells used in the assay. Telomerase activity of Rnase-pretreated cells or heat-treated cells, and human normal peripheral blood leukocyte(Leu) were negative. The result of this method was available within a few hours and was handled without radioisotope. Further studies should be taken to detect telomerase activity in quantitation.

  3. Cancer-Specific Telomerase Reverse Transcriptase (TERT Promoter Mutations: Biological and Clinical Implications

    Directory of Open Access Journals (Sweden)

    Tiantian Liu

    2016-07-01

    Full Text Available The accumulated evidence has pointed to a key role of telomerase in carcinogenesis. As a RNA-dependent DNA polymerase, telomerase synthesizes telomeric DNA at the end of linear chromosomes, and attenuates or prevents telomere erosion associated with cell divisions. By lengthening telomeres, telomerase extends cellular life-span or even induces immortalization. Consistent with its functional activity, telomerase is silent in most human normal somatic cells while active only in germ-line, stem and other highly proliferative cells. In contrast, telomerase activation widely occurs in human cancer and the enzymatic activity is detectable in up to 90% of malignancies. Recently, hotspot point mutations in the regulatory region of the telomerase reverse transcriptase (TERT gene, encoding the core catalytic component of telomerase, was identified as a novel mechanism to activate telomerase in cancer. This review discusses the cancer-specific TERT promoter mutations and potential biological and clinical significances.

  4. Cancer-Specific Telomerase Reverse Transcriptase (TERT) Promoter Mutations: Biological and Clinical Implications

    Science.gov (United States)

    Liu, Tiantian; Yuan, Xiaotian; Xu, Dawei

    2016-01-01

    The accumulated evidence has pointed to a key role of telomerase in carcinogenesis. As a RNA-dependent DNA polymerase, telomerase synthesizes telomeric DNA at the end of linear chromosomes, and attenuates or prevents telomere erosion associated with cell divisions. By lengthening telomeres, telomerase extends cellular life-span or even induces immortalization. Consistent with its functional activity, telomerase is silent in most human normal somatic cells while active only in germ-line, stem and other highly proliferative cells. In contrast, telomerase activation widely occurs in human cancer and the enzymatic activity is detectable in up to 90% of malignancies. Recently, hotspot point mutations in the regulatory region of the telomerase reverse transcriptase (TERT) gene, encoding the core catalytic component of telomerase, was identified as a novel mechanism to activate telomerase in cancer. This review discusses the cancer-specific TERT promoter mutations and potential biological and clinical significances. PMID:27438857

  5. Cancer-Specific Telomerase Reverse Transcriptase (TERT) Promoter Mutations: Biological and Clinical Implications.

    Science.gov (United States)

    Liu, Tiantian; Yuan, Xiaotian; Xu, Dawei

    2016-01-01

    The accumulated evidence has pointed to a key role of telomerase in carcinogenesis. As a RNA-dependent DNA polymerase, telomerase synthesizes telomeric DNA at the end of linear chromosomes, and attenuates or prevents telomere erosion associated with cell divisions. By lengthening telomeres, telomerase extends cellular life-span or even induces immortalization. Consistent with its functional activity, telomerase is silent in most human normal somatic cells while active only in germ-line, stem and other highly proliferative cells. In contrast, telomerase activation widely occurs in human cancer and the enzymatic activity is detectable in up to 90% of malignancies. Recently, hotspot point mutations in the regulatory region of the telomerase reverse transcriptase (TERT) gene, encoding the core catalytic component of telomerase, was identified as a novel mechanism to activate telomerase in cancer. This review discusses the cancer-specific TERT promoter mutations and potential biological and clinical significances. PMID:27438857

  6. Multiple Mechanisms Contribute to the Cell Growth Defects Imparted by Human Telomerase Insertion in Fingers Domain Mutations Associated with Premature Aging Diseases.

    Science.gov (United States)

    Chu, Tsz Wai; MacNeil, Deanna Elise; Autexier, Chantal

    2016-04-15

    Normal human stem cells rely on low levels of active telomerase to sustain their high replicative requirements. Deficiency in telomere maintenance mechanisms leads to the development of premature aging diseases, such as dyskeratosis congenita and aplastic anemia. Mutations in the unique "insertion in fingers domain" (IFD) in the human telomerase reverse transcriptase catalytic subunit (hTERT) have previously been identified and shown to be associated with dyskeratosis congenita and aplastic anemia. However, little is known about the molecular mechanisms impacted by these IFD mutations. We performed comparative functional analyses of disease-associated IFD variants at the molecular and cellular levels. We report that hTERT-P721R- and hTERT-R811C-expressing cells exhibited growth defects likely due to impaired TPP1-mediated recruitment of these variant enzymes to telomeres. We showed that activity and processivity of hTERT-T726M failed to be stimulated by TPP1-POT1 overexpression and that dGTP usage by this variant was less efficient compared with the wild-type enzyme. hTERT-P785L-expressing cells did not show growth defects, and this variant likely confers cell survival through increased DNA synthesis and robust activity stimulation by TPP1-POT1. Altogether, our data suggest that multiple mechanisms contribute to cell growth defects conferred by the IFD variants. PMID:26887940

  7. Nucleolar protein PinX1p regulates telomerase by sequestering its protein catalytic subunit in an inactive complex lacking telomerase RNA

    OpenAIRE

    Lin, Jue; Elizabeth H. Blackburn

    2004-01-01

    Human TRF1-binding protein PinX1 inhibits telomerase activity. Here we report that overexpression of yeast PinX1p (yPinX1p) results in shortened telomeres and decreased in vitro telomerase activity. yPinX1p coimmunoprecipitated withyeast telomerase protein Est2p even in cells lacking the telomerase RNA TLC1, or the telomerase-associated proteins Est1p and Est3p. Est2p regions required for binding to yPinX1p or TLC1 were similar. Furthermore, we found two distinct Est2p complexes exist, contai...

  8. Comparison of Inhibitory Effect of Curcumin Nanoparticles and Free Curcumin in Human Telomerase Reverse Transcriptase Gene Expression in Breast Cancer

    OpenAIRE

    Nosratollah Zarghami; Abbas Rami; Fatemeh Kazemi-Lomedasht

    2013-01-01

    Purpose: Telomerase is expressed in most cancers, including breast cancer. Curcumin, a polyphenolic compound that obtained from the herb of Curcuma longa, has many anticancer effects. But, its effect is low due to poor water solubility. In order to improve its solubility and drug delivery, we have utilized a β-cyclodextrin-curcumin inclusion complex. Methods: To evaluate cytotoxic effects of cyclodextrin-curcumin and free curcumin, MTT assay was done. Cells were treated with equal concentrati...

  9. A novel inhibitor of human telomerase derived from 10H-indolo[3,2-b]quinoline.

    Science.gov (United States)

    Caprio, V; Guyen, B; Opoku-Boahen, Y; Mann, J; Gowan, S M; Kelland, L M; Read, M A; Neidle, S

    2000-09-18

    The bis-dimethylaminoethyl derivative of quindoline (10H-indolo[3,2-b]quinoline), an alkaloid from the West African shrub Cryptolepis sanguinolenta, has been synthesised. This has been shown to have modest cytotoxicity, as well as inhibitory activity against the telomerase enzyme. It is hypothesised that the latter activity is due to stabilisation of an intermediate guanine-quadruplex complex, in accordance with computer modelling. PMID:10999471

  10. Gain of human telomerase RNA gene is associated with progression of cervical intraepithelial neoplasia grade Ⅰ or Ⅱ

    Institute of Scientific and Technical Information of China (English)

    LAN Yong-lian; YU Lan; JIA Chan-wei; WU Yu-mei; WANG Shu-yu

    2012-01-01

    Background The 3q26 chromosome region,where the human telomerase RNA gene (hTERC) is located,is a biomarker for cervical cancer and precancerous lesions.The aim of this study was to confirm the value of measuring hTERC gene gain in predicting the progression of cervical intraepithelial neoplasia grade Ⅰ or Ⅱ (CIN-Ⅰ and -Ⅱ,respectively) to CIN-Ⅲ and cervical cancer.Methods Liquid-based cytological samples from 54 patients with CIN-Ⅰ or CIN-Ⅱ lesions were enrolled in this study.Follow-up was performed with colposcopy and biopsy within 24 months after the diagnosis of CIN-Ⅰ or CIN-Ⅱ.Copy numbers of the hTERC gene were measured by fluorescence in situ hybridization with a dual-color probe mix containing the hTERC gene probe (labeled red) and the control,the chromosome 3 centromere-specific probe (labeled green).Results All patients whose lesions progressed from CIN-Ⅰ or CIN-Ⅱ to CIN-Ⅲ displayed a gain of the hTERC gene,whereas patients where the hTERC gene was not amplified did not subsequently progress to CIN-Ⅲ or cervical cancer.The signal ratio pattem per cell was recorded as N∶N (green∶ red).The numbers of cells with the signal ratio pattern of 4∶4or N∶≥5 in patients whose lesions progressed to CIN-Ⅲ were significantly higher than those whose lesions did not progress.Significantly,none of the patients with a 4∶4 signal ratio pattern regressed spontaneously.Conclusions In conclusion,measurement of hTERC gene gain in CIN-Ⅰ or CIN-Ⅱ patients using liquid-based cytological samples could be a useful biomarker to predict the progression of such cervical lesions.In addition,a 4∶4 or N∶≥5 signal ratio pattern may indicate the unlikeness of spontaneous regression of CIN-Ⅰ or CIN-Ⅱ lesions.

  11. Characterization of a novel telomerase-immortalized human endometrial stromal cell line, St-T1b

    Directory of Open Access Journals (Sweden)

    Brosens Jan J

    2009-07-01

    Full Text Available Abstract Background Coordinated differentiation of the endometrial compartments in the second half of the menstrual cycle is a prerequisite for the establishment of pregnancy. Endometrial stromal cells (ESC decidualize under the influence of ovarian progesterone to accommodate implantation of the blastocyst and support establishment of the placenta. Studies into the mechanisms of decidualization are often hampered by the lack of primary ESC. Here we describe a novel immortalized human ESC line. Methods Primary ESC were immortalized by the transduction of telomerase. The resultant cell line, termed St-T1b, was characterized for its morphological and biochemical properties by immunocytochemistry, RT-PCR and immunoblotting. Its progestational response was tested using progesterone and medroxyprogesterone acetate with and without 8-Br-cAMP, an established inducer of decidualization in vitro. Results St-T1b were positive for the fibroblast markers vimentin and CD90 and negative for the epithelial marker cytokeratin-7. They acquired a decidual phenotype indistinguishable from primary ESC in response to cAMP stimulation. The decidual response was characterized by transcriptional activation of marker genes, such as PRL, IGFBP1, and FOXO1, and enhanced protein levels of the tumor suppressor p53 and the metastasis suppressor KAI1 (CD82. Progestins alone had no effect on St-T1b cells, but medroxyprogesterone acetate greatly enhanced the cAMP-stimulated expression of IGFBP-1 after 3 and 7 days. Progesterone, albeit more weakly, also augmented the cAMP-induced IGFBP-1 production but only after 7 days of treatment. The cell line remained stable in continuous culture for more than 150 passages. Conclusion St-T1b express the appropriate phenotypic ESC markers and their decidual response closely mimics that of primary cultures. Decidualization is efficiently induced by cAMP analog and enhanced by medroxyprogesterone acetate, and, to a lesser extent, by natural

  12. Effective siRNA targets screening for human telomerase reverse transcriptase

    Institute of Scientific and Technical Information of China (English)

    Yun Xia; Ru-Xian Lin; Su-Jun Zheng; Ying Yang; Xiao-Chen Bo; Dao-Yin Zhu; Sheng-Qi Wang

    2005-01-01

    AIM: To study the inhibitory effects of siRNAs targeting different hTERT sequences and to screen the effective siRNA sequence.METHODS: Five double-stranded siRNAs targeting coding and non-coding regions of hTERT gene were designed and synthesized by T7 transcription system in vitro. siRNA4sequence was screened by full length gene targeting technique and the rest of the siRNA sequences were selected randomly. After being purified by ethanol precipitation, the siRNAs were transfected to the human hepatocellular carcinoma cell (HepG2) by Lipofectamine 2000TM. At 48-72 h after siRNAs transfection, MTT assay,RT-PCR and Western-blot were applied to evaluate the effects of siRNAs on cell growth, mRNA and protein expression level of hTERT gene, respectively.RESULTS: Compared to the control cells, the cells treated with the five double-stranded siRNAs exhibited different degrees of inhibition of cell proliferation in a dose-dependent manner. siRNA2 and siRNA4, exhibited obvious effects of inhibiting hTERT mRNA and protein expression in HepG2cells.CONCLUSION: siRNAs targeting different hTERT sequences have significantly various inhibitory effects on hTERT gene expression. The siRNA sequence screened by full length gene targeting technique has comparable inhibitory effect with the rest siRNA sequences screened by random selection, suggesting that siRNAs and antisense oligonucleic acids may have the same effective target sites. Compared with chemical synthesis method,synthesizing double-stranded siRNA by T7 transcription system in vitro is a rapid, simple, and inexpensive method suitable for screening high-effect siRNA targeting site for specific gene.

  13. Cancer. TERT promoter mutations and telomerase reactivation in urothelial cancer.

    Science.gov (United States)

    Borah, Sumit; Xi, Linghe; Zaug, Arthur J; Powell, Natasha M; Dancik, Garrett M; Cohen, Scott B; Costello, James C; Theodorescu, Dan; Cech, Thomas R

    2015-02-27

    Reactivation of telomerase, the chromosome end-replicating enzyme, drives human cell immortality and cancer. Point mutations in the telomerase reverse transcriptase (TERT) gene promoter occur at high frequency in multiple cancers, including urothelial cancer (UC), but their effect on telomerase function has been unclear. In a study of 23 human UC cell lines, we show that these promoter mutations correlate with higher levels of TERT messenger RNA (mRNA), TERT protein, telomerase enzymatic activity, and telomere length. Although previous studies found no relation between TERT promoter mutations and UC patient outcome, we find that elevated TERT mRNA expression strongly correlates with reduced disease-specific survival in two independent UC patient cohorts (n = 35; n = 87). These results suggest that high telomerase activity may be a better marker of aggressive UC tumors than TERT promoter mutations alone. PMID:25722414

  14. Telomerase Structure Paves the way for New Cancer Therapies

    Energy Technology Data Exchange (ETDEWEB)

    Skordalakes, S.

    2009-01-01

    Inappropriate activation of a single enzyme, telomerase, is associated with the uncontrollable proliferation of cells observed in as many as 90% of all of human cancers. Since the mid-1990s, when telomerase activity was detected in human tumors, scientists have eyed the enzyme as an ideal target for developing broadly effective anticancer drugs. One of the missing links in the effort to identify such therapies has been the high-resolution structure of the enzyme, a powerful tool used for the identification and development of clinical drugs. A recent structure of the catalytic subunit of teleomerase from the Skordalakes laboratory, a major advancement in the field of telomeres, has opened the door to the development of new, broadly effective cancer drugs, as well as anti-aging therapies. Here we present a brief description of telomerase biology, current efforts to identify telomerase function modulators and the potential importance of the telomerase structure in future drug development.

  15. In vitro transfection of the hepatitis B virus PreS2 gene into the human hepatocarcinoma cell line HepG2 induces upregulation of human telomerase reverse transcriptase

    International Nuclear Information System (INIS)

    The preS2 domain is the minimal functional unit of transcription activators that is encoded by the Hepatitis B virus (HBV) surface (S) gene. It is present in more than one-third of the HBV-integrates in HBV induced hepatocarcinoma (HCC). To further understand the functional role of PreS2 in hepatocytes, a PreS2 expression plasmid, pcS2, was constructed and stably transfected into HepG2 cells. We conducted growth curve and colony-forming assays to study the impact of PreS2 expression on cell proliferation. Cells transfected with PreS2 proliferated more rapidly and formed colonies in soft agar. PreS2 expressing cells also induced upregulation of human telomerase reverse transcriptase (hTERT) and telomerase activation by RT-PCR and the modified TRAP assay. Blocking expression of hTERT with antisense oligonuleotide reversed the growth rate in cells stably transfected with PreS2. Our data suggest that PreS2 may increase the malignant transformation of human HCC cell line HepG2 by upregulating hTERT and inducing telomerase activation

  16. The differentiation status of primary gonadal germ cell tumors correlates inversely with telomerase activity and the expression level of the gene encoding the catalytic subunit of telomerase

    International Nuclear Information System (INIS)

    The activity of the ribonucleoprotein enzyme telomerase is detectable in germ, stem and tumor cells. One major component of telomerase is human telomerase reverse transcriptase (hTERT), which encodes the catalytic subunit of telomerase. Here we investigate the correlation of telomerase activity and hTERT gene expression and the differentiation status of primary testicular germ cell tumors (TGCT). Telomerase activity (TA) was detected by a quantitative telomerase PCR ELISA, and hTERT mRNA expression was quantified by online RT-PCR in 42 primary testicular germ cell tumors. The control group consisted of benign testicular biopsies from infertile patients. High levels of telomerase activity and hTERT expression were detected in all examined undifferentiated TGCTs and in the benign testicular tissue specimens with germ cell content. In contrast, differentiated teratomas and testicular control tissue without germ cells (Sertoli-cell-only syndrome) showed no telomerase activity and only minimal hTERT expression. These findings demonstrate an inverse relationship between the level of telomerase activity and hTERT mRNA expression and the differentiation state of germ cell tumors. Quantification of telomerase activity and hTERT mRNA expression enables a new molecular-diagnostic subclassification of germ cell tumors that describes their proliferation potential and differentiation status

  17. Live Cell Imaging Reveals the Dynamics of Telomerase Recruitment to Telomeres.

    Science.gov (United States)

    Schmidt, Jens C; Zaug, Arthur J; Cech, Thomas R

    2016-08-25

    Telomerase maintains genome integrity by adding repetitive DNA sequences to the chromosome ends in actively dividing cells, including 90% of all cancer cells. Recruitment of human telomerase to telomeres occurs during S-phase of the cell cycle, but the molecular mechanism of the process is only partially understood. Here, we use CRISPR genome editing and single-molecule imaging to track telomerase trafficking in nuclei of living human cells. We demonstrate that telomerase uses three-dimensional diffusion to search for telomeres, probing each telomere thousands of times each S-phase but only rarely forming a stable association. Both the transient and stable association events depend on the direct interaction of the telomerase protein TERT with the telomeric protein TPP1. Our results reveal that telomerase recruitment to telomeres is driven by dynamic interactions between the rapidly diffusing telomerase and the chromosome end. PMID:27523609

  18. Expression of Telomerase Activity in Gastric Cancer Cells

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Objective To study the relationship between telomerase activity and biological behavior in human gastric cells and appraise the clinical significance of detecting telomerase activity. Methods The telomerase activity in 47 gastric cancer tissue samples,their matched nomal tissues,7 gastric ulcer and 2 gastric cancer cell lines was detected using a PCR-based non-radioisotopic telomeric repeat amplification protocol(TRAP) assay. Results None of the 47 samples from normal gastric tissues expressed telomerase activity.The 41 of 47 cases of gastric cancer presented telomerase activity with an 87.2% positive rate (P<0.001). 2/2 gastric cancer cell lines and 0/7 gastric ulcer line were also positive for telmerase activity.The activity of telomerase was associated with the pathological differentiation of gastric cancer. Conclusion Telomerase activity may be related to the biological behavior of gastric cancer and can help in assessing the malignant poten-tial of gastric cancer.Telomerase activity will be a good diagnostic marker for the detection of gastric cancer.

  19. Upregulation of human telomerase reverse transcriptase mRNA expression by in vitro transfection of hepatitis B virus X gene into human hepatocarcinoma and cholangiocarcinoma cells

    Institute of Scientific and Technical Information of China (English)

    Zhen-Liang Qu; Sheng-Quan Zou; Nai-Qiang Cui; Xian-Zhong Wu; Ming-Fang Qin; Di Kong; Zhen-Li Zhou

    2005-01-01

    AIM: To study the changes of human telomerase reverse transcriptase (hTERT) mRNA expression in human hepatocarcinoma cell lines (HepG2) and cholangiocarcinoma cell lines (QBC939) after HBx gene transfection and to illustrate the significance of transcriptional regulation of hTERT gene by HBx gene in the carcinogenesis.METHODS: HepG2 and QBC939 cell lines were cultured and co-transfected with eukaryotic expression vector containing the HBx coding region and cloning vector containing enhanced green fluorescent protein (EGFP) coding sequence using lipid-mediated gene transduction technique. Thirty-six hours after transfection, EGFP expression in cells was used as the indicator of successful transfection. Flow cytometry was performed to determine the transfection efficiency.Cells were harvested and total RNA was extracted using TRIzol() reagent. The expression of hTERT mRNA in HepG2and QBC939 cell lines was assayed by reverse transcriptionpolymerase chain reaction. The expression of HBx protein in both cell lines was detected by immunocytochemical staining and Western blotting.RESULTS: Flow cytometry showed that the transfection efficiency was 46.4% in HepG2 cells and 29.6% in QBC939cells for both HBx gene expression vector and blank vector. The expression of hTERT mRNA was meaningfully increased in HepG2 and QBC939 cell lines when transfected with HBx gene expression vector compared to those transfected with OPTI-MEM medium and blank vector.Immunocytochemical staining and Western blotting revealed HBx protein expression in HepG2 and QBC939cells only when transfected with HBx gene.CONCLUSION: HBx gene transfection can upregulate the transcriptional expression of hTERT mRNA. The transactivation of hTERT gene by HBx gene is a newfound mechanism for pathogenesis of hepatocarcinomas and cholangiocarcinomas after HBV infection.

  20. Human adipose tissue possesses a unique population of pluripotent stem cells with nontumorigenic and low telomerase activities: potential implications in regenerative medicine.

    Science.gov (United States)

    Ogura, Fumitaka; Wakao, Shohei; Kuroda, Yasumasa; Tsuchiyama, Kenichiro; Bagheri, Mozhdeh; Heneidi, Saleh; Chazenbalk, Gregorio; Aiba, Setsuya; Dezawa, Mari

    2014-04-01

    In this study, we demonstrate that a small population of pluripotent stem cells, termed adipose multilineage-differentiating stress-enduring (adipose-Muse) cells, exist in adult human adipose tissue and adipose-derived mesenchymal stem cells (adipose-MSCs). They can be identified as cells positive for both MSC markers (CD105 and CD90) and human pluripotent stem cell marker SSEA-3. They intrinsically retain lineage plasticity and the ability to self-renew. They spontaneously generate cells representative of all three germ layers from a single cell and successfully differentiate into targeted cells by cytokine induction. Cells other than adipose-Muse cells exist in adipose-MSCs, however, do not exhibit these properties and are unable to cross the boundaries from mesodermal to ectodermal or endodermal lineages even under cytokine inductions. Importantly, adipose-Muse cells demonstrate low telomerase activity and transplants do not promote teratogenesis in vivo. When compared with bone marrow (BM)- and dermal-Muse cells, adipose-Muse cells have the tendency to exhibit higher expression in mesodermal lineage markers, while BM- and dermal-Muse cells were generally higher in those of ectodermal and endodermal lineages. Adipose-Muse cells distinguish themselves as both easily obtainable and versatile in their capacity for differentiation, while low telomerase activity and lack of teratoma formation make these cells a practical cell source for potential stem cell therapies. Further, they will promote the effectiveness of currently performed adipose-MSC transplantation, particularly for ectodermal and endodermal tissues where transplanted cells need to differentiate across the lineage from mesodermal to ectodermal or endodermal in order to replenish lost cells for tissue repair. PMID:24256547

  1. Telomerase and the aging process

    OpenAIRE

    Hornsby, Peter J.

    2007-01-01

    The level of telomerase activity is important in determining telomere length in aging cells and tissues. Here evidence on the importance of telomerase activity is reviewed with respect to aging rates of mammalian species and the health and life span of individuals within a species. The significance of telomerase reactivation for both cancer development and for immortalizing cells for therapeutic processes is assessed.

  2. The Clinical Implications of Human Telomerase Reverse Transcriptase Expression in Grade and Prognosis of Gliomas: a Systematic Review and Meta-analysis.

    Science.gov (United States)

    Li, Jing; Li, Huiying; Liu, Jihong; Feng, Bin; Feng, Man; Lv, Baoyu; Cheng, Shaomei; Yang, Xiangshan

    2016-07-01

    Human telomerase reverse transcriptase (hTERT), a ribonucleoprotein, is reported as an important complex, which is required for stability of DNA molecular structure at the rear of the chromosome. Until now, hTERT has been linked to cell immortalization and tumorigenesis. A couple of articles have been published about the telomerase function in the gliomas; however, these results are conflicting in some degree. Thus, it is crucial to perform a meta-analysis to identify their real actions. We included eligible articles, and estimated odds ratios (ORs) with 95 % confidence intervals (95 % CIs). In our meta-analysis, all 15 eligible articles included 932 patients. Results from 10 studies on WHO grade showed that high hTERT gene or protein expression in glioma tissues was obviously related to high WHO grade (III + IV) (OR 2.45, 95 % CI 1.92-3.13; p = 0.000). What is more, hTERT expression was not associated with old age (OR 0.91, 95 % CI 0.72-1.16; p = 0.448) as well as gender (OR 1.06, 95 % CI 0.82-1.37; p = 0.664). Importantly, hTERT expression was significantly associated with 5-year overall survival (OS; n = 3; hazard ratio (HR) 2.25, 95 % CI 1.36-3.70; p = 0.002) of glioma patients. No heterogeneity was found in all studies. In conclusion, this meta-analysis suggests that hTERT is significantly associated with high glioma grade and poor 5-year overall survival, and pathological test of hTERT mRNA and protein in glioma tissues should be suggested as criteria of glioma grade in the clinical practice. PMID:25895660

  3. [Telomerase reverse transcriptase (TERT) promoter mutations in the tumors of human endocrine organs: Biological and prognostic value].

    Science.gov (United States)

    Selivanova, L S; Volganova, K S; Abrosimov, A Y U

    2016-01-01

    The analysis of the data available in the literature has shown that telomerase reverse transcriptase TERT promoter may serve as promising markers of malignancy, aggressive disease course, and poor prognosis for malignant tumors of endocrine organs. Considering the established association of mutations with tumors having a poor prognosis (high-grade and anaplastic carcinoma of the thyroid), it is reasonable to perform prognostic-value investigations in a group of low-grade thyroid carcinomas that may occasionally recur and may be resistant to radioactive iodine therapy, i.e. can demonstrate a poor course and prognosis. TERT promoter mutations may be a specific marker of the clinically aggressive forms of adrenocortical carcinoma, but the determination of its diagnostic value calls for additional investigations that will have the larger number cases and establish the association with clinical features and survival rates. PMID:27077147

  4. A telomerase immortalized human proximal tubule cell line with a truncation mutation (Q4004X in polycystin-1.

    Directory of Open Access Journals (Sweden)

    Brittney-Shea Herbert

    Full Text Available Autosomal dominant polycystic kidney disease (ADPKD is associated with a variety of cellular phenotypes in renal epithelial cells. Cystic epithelia are secretory as opposed to absorptive, have higher proliferation rates in cell culture and have some characteristics of epithelial to mesenchymal transitions. In this communication we describe a telomerase immortalized cell line that expresses proximal tubule markers and is derived from renal cysts of an ADPKD kidney. These cells have a single detectable truncating mutation (Q4004X in polycystin-1. These cells make normal appearing but shorter cilia and fail to assemble polycystin-1 in the cilia, and less uncleaved polycystin-1 in membrane fractions. This cell line has been maintained in continuous passage for over 35 passages without going into senescence. Nephron segment specific markers suggest a proximal tubule origin for these cells and the cell line will be useful to study mechanistic details of cyst formation in proximal tubule cells.

  5. Telomerer og telomerase

    DEFF Research Database (Denmark)

    Bendix, Laila; Kølvraa, Steen

    2010-01-01

    In 2009 the Nobel Prize in Medicine was awarded to EH Blackburn, CW Greider and JW Szostak for their work on "How chromosomes are protected by telomeres and the enzyme telomerase". Telomeres are specialized DNA structures localized at the end of linear chromosomes. Telomeres are known as the...

  6. The low-toxicity 9-cis UAB30 novel retinoid down-regulates the DNA methyltransferases and has anti-telomerase activity in human breast cancer cells

    OpenAIRE

    HANSEN, NATHAN J.; WYLIE, REBECCA C.; Phipps, Sharla M. O.; Love, William K.; Andrews, Lucy G.; Tollefsbol, Trygve O.

    2007-01-01

    Retinoic acids and their derivatives potentiate anti-cancer effects in breast cancer cells. The aberrant expression of telomerase is critical to the continued proliferation of most cancer cells. Thus, telomerase is an attractive target for chemo-prevention and treatment of breast cancer. 9cUAB30 is a novel synthetic retinoid X receptor-selective retinoic acid (RA) that effectively reduces the tumorigenic phenotype in mouse breast carcinoma with lower toxic effects than natural retinoid treatm...

  7. Expression of telomerase hTERT in human non-small cell lung cancer and its correlation with c-myc gene

    Institute of Scientific and Technical Information of China (English)

    耿志华; 张敦华; 刘银坤

    2003-01-01

    Objective To investigate the expression of human telomerase catalytic subunit, hTERT, in human non-small cell lung cancer (NSCLC) and its correlations to c-myc gene.Methods hTERT and c-myc mRNA expressions were detected by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). Statistical correlation analysis was made to estimate whether there was interrelation between them.Results Positive rate of hTERT expression in 51 surgically resected lung cancer specimens was 86.3%, significantly higher than that in adjacent non-neoplastic lung tissues and benign lesions, which were 14.3% and 27.3% respectively. No statistical significance was observed between the frequency of hTERT expression and histologic types, degree of differentiation, TNM stages, tumor size or lymph nodes metastases. Correlation analysis revealed that the expression of c-myc gene was significantly related to that of hTERT (correlation coefficient, r=0.633, P<0.001).Conclusions hTERT may be a useful tumor marker in diagnosing lung cancer. Significant correlation between the expression of hTERT and c-myc mRNA indicates that the activation and up-regulation of hTERT might be conferred by over-expression of c-myc gene.

  8. RNA Binding Domain of Telomerase Reverse Transcriptase

    OpenAIRE

    Lai, Cary K.; Mitchell, James R.; Collins, Kathleen

    2001-01-01

    Telomerase is a ribonucleoprotein reverse transcriptase that extends the ends of chromosomes. The two telomerase subunits essential for catalysis in vitro are the telomerase reverse transcriptase (TERT) and the telomerase RNA. Using truncations and site-specific mutations, we identified sequence elements of TERT and telomerase RNA required for catalytic activity and protein-RNA interaction for Tetrahymena thermophila telomerase. We found that the TERT amino and carboxyl termini, although evol...

  9. TTAGG-repeat telomeres and characterization of telomerase in the beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae).

    Science.gov (United States)

    Gong, H; Zhu, W; Zhang, J; Li, X; Meng, Q; Zhou, G; Wang, M; Wang, H; Miao, L; Qin, Q; Zhang, H

    2015-06-01

    Telomeres are maintained usually by telomerase, a specialized reverse transcriptase that adds this sequence to chromosome ends. In this study, telomerase activity was detected in the in different somatic tissues, such as midgut and fat bodies, by the telomeric repeat amplification protocol (TRAP) in Spodoptera exigua. The structure of the telomeres of S. exigua was evaluated by sequence analysis of the TRAP products, revealing that the telomerase synthesized a (TTAGG)n repeat. The presence of a telomerase reverse transcriptase (TERT) subunit coding gene has been cloned, sequenced and expressed in vitro successively. Notably, the S. exigua telomerase (SpexTERT) gene structure lacks the N-terminal GQ motif. Telomerase contains a large RNA subunit, TER, and a protein catalytic subunit, TERT. Here we report an in vitro system that was reconstructed by all components of the telomerase complex, a purified recombinant SpexTERT without a N-terminal GQ motif and a mutant human telomerase RNA (TER), showed telomerase activity. Together, these results suggest the GQ motif is not essential for telomerase catalysis. PMID:25689229

  10. Biologic function and clinical potential of telomerase and associated proteins in cardiovascular tissue repair and regeneration

    OpenAIRE

    Madonna, Rosalinda; De Caterina, Raffaele; Willerson, James T.; Geng, Yong-Jian

    2010-01-01

    Telomeres comprise long tracts of double-stranded TTAGGG repeats that extend for 9–15 kb in humans. Telomere length is maintained by telomerase, a specialized ribonucleoprotein that prevents the natural ends of linear chromosomes from undergoing inappropriate repair, which could otherwise lead to deleterious chromosomal fusions. During the development of cardiovascular tissues, telomerase activity is strong but diminishes with age in adult hearts. Dysfunction of telomerase is associated with ...

  11. Herpesvirus Telomerase RNA (vTR) with a Mutated Template Sequence Abrogates Herpesvirus-Induced Lymphomagenesis

    OpenAIRE

    Kaufer, Benedikt B; Sina Arndt; Sascha Trapp; Nikolaus Osterrieder; Jarosinski, Keith W.

    2011-01-01

    Telomerase reverse transcriptase (TERT) and telomerase RNA (TR) represent the enzymatically active components of telomerase. In the complex, TR provides the template for the addition of telomeric repeats to telomeres, a protective structure at the end of linear chromosomes. Human TR with a mutation in the template region has been previously shown to inhibit proliferation of cancer cells in vitro. In this report, we examined the effects of a mutation in the template of a virus encoded TR (vTR)...

  12. Polymorphisms in human telomerase reverse transcriptase (hTERT) gene and susceptibility to gastric cancer in a Turkish population: Hospital-based case-control study.

    Science.gov (United States)

    Bayram, Süleyman; Ülger, Yakup; Sümbül, Ahmet Taner; Kaya, Berrin Yalinbaş; Genç, Ahmet; Rencüzoğullari, Eyyüp; Dadaş, Erdoğan

    2016-07-01

    Erosion of telomeres, tandem nucleotide repeats (TTAGGG)n that cap the end of eukaryotic chromosomes, has been related with carcinogenesis. The human telomerase reverse transcriptase (hTERT) gene is encoded the rate-limiting catalytic subunit of the telomerase complexes, which is essential for the protection of telomeric DNA length and chromosomal stability. The purpose of this study was to examine the effect of four functional single nucleotide polymorphisms (SNPs) of hTERT (rs2736109 G>A, rs2735940 T>C, rs2853669 A>G and rs2736100 T>G) on susceptibility to gastric cancer (GC) in Turkish population. The genotype frequency of hTERT rs2736109 G>A, rs2735940 T>C, rs2853669 A>G and rs2736100 T>G polymorphisms were determined by using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and TaqMan methods in 104 subjects with GC and 209 healthy control subjects. We found that hTERT rs2736109 G>A (AA+AG vs. GG OR=1.68 95% CI=1.01-2.81, P=0.04), rs2735940 T>C (CC vs. CT+TT: OR=2.53 95% CI=1.01-6.13, P=0.03), and rs2736100 T>G (TT vs. TG+GG: OR=2.27 95% CI=1.23-4.17, P=0.006) polymorphisms were associated with risk of GC. In the haplotype analysis, hTERT Grs2736109/Trs2735940/Ars2853669/Grs2736100 haplotype was also related with an increased risk of GC (OR=1.75; 95% CI: 1.05-2.93, P=0.03). Because this is the first study regarding the hTERT rs2736109 G>A, rs2735940 T>C, rs2853669 A>G and rs2736100 T>G polymorphisms and the risk of GC susceptibility in the literature, further independent studies are needed to verify our results in a larger sample sizes, as well as in patients of different populations. PMID:27016301

  13. Inhibition of Leukemic Cell Telomerase Activity by Antisense Phosphorothioate Oligodeoxynucleotides

    Institute of Scientific and Technical Information of China (English)

    HEDongmei; ZHANGYuan

    2002-01-01

    Objective To evaluate the effect of human telomerase reverse transcriptase(hTERT) gene antisense oligodeoxynucleotide (ASON) on telomerase activity in K562 cells.Methods Telomerase activity was detemined by polymerase chain reaction enzyme-linked immunoassay (PCR-ELISA) in K562 cells treated with ASODN and hTERTmRNA expression was detected by reverse transcriptase polymerase chain reaction (RT-PCR). Results The hTERTmRNA level was decreased,and telomerase activity was significantly inhibited when the K562 cells were treated with ASODN for 48 h. Conclusion It is suggested that hTETR ASODN might specifically inhibit telomrase activity of K562 cells at translation level,and it is further proved that hTERT gene has significant correlation with telopmerase activity.

  14. Telomerase, mitochondria and oxidative stress

    OpenAIRE

    Saretzki, Gabriele

    2009-01-01

    Abstract Telomerase plays an important role in cellular proliferation capacity and survival under conditions of stress. A large part of this protective function is due to telomere capping and maintenance. Thus it contributes to cellular immortality in stem cells and cancer. Recently, evidence has accumulated that telomerase can contribute to cell survival and stress resistance in a largely telomere-independent manner. Telomerase has been shown to shuttle dynamically between differe...

  15. A model for triple helix formation on human telomerase reverse transcriptase (hTERT) promoter and stabilization by specific interactions with the water soluble perylene derivative, DAPER.

    Science.gov (United States)

    Rossetti, Luigi; D'Isa, Giuliana; Mauriello, Clementina; Varra, Michela; De Santis, Pasquale; Mayol, Luciano; Savino, Maria

    2007-08-01

    The promoter of human telomerase reverse transcriptase (hTERT) gene, in the region from -1000 to +1, contains two homopurine-homopyrimidine sequences (-835/-814 and -108/-90), that can be considered as potential targets to triple helix forming oligonucleotides (TFOs) for applying antigene strategy. We have chosen the sequence (-108/-90) on the basis of its unfavorable chromatin organization, evaluated by theoretical nucleosome positioning and nuclease hypersensitive sites mapping. On this sequence, anti-parallel triplex with satisfactory thermodynamic stability is formed by two TFOs, having different lengths. Triplex stability is significantly increased by specific interactions with the perylene derivative N,N'-bis[3,3'-(dimethylamino) propylamine]-3,4,9,10-perylenetetracarboxylic diimide (DAPER). Since DAPER is a symmetric molecule, the induced Circular Dichroism (CD) spectra in the range 400-600 nm allows us to obtain information on drug binding to triplex and duplex DNA. The drug-induced ellipticity is significantly higher in the case of triplex with respect to duplex and, surprisingly, it increases at decreasing of DNA. A model is proposed where self-stacked DAPER binds to triplex or to duplex narrow grooves. PMID:17560709

  16. Telomerase expression in sebaceous carcinoma of the eyelid

    Institute of Scientific and Technical Information of China (English)

    李彬; 李宁东; 顼晓琳; 郑邦和; 孙宪丽; 李辽青; 陈长喜

    2004-01-01

    Background In humans telomerase is expressed in most cancers and immortal cell lines, and astivation of telomerase may play important roles in tumorigenesis and immortalization. This study was to investigate the roles of telomerase activity (TA) and human telomerase RNA (hTR) in sebaceous carcinoma of the eyelid.Methods The telomerase repeated amplification protocal (TRAP) was used to demonstrate telomerase activity in 12 cases of sebaceous carcinoma of the eyelid. In situ hybridization (ISH) was used to demonstrate the expression of hTR in 55 cases of paraffin-embedded sebaceous carcinoma of the eyelid, and the results were compared with the proliferative index determined by Mib-1 immuno-labeling, histological patterns and recurrence of the tumor.Results Different telomerase activity was shown in the 12 cases of sebaceous carcinoma of the eyelid. The positive expression of hTR was 85.5% (47/55) in tumor cells, but not in the adjacent tissues. The positive expression of hTR was correlated with the proliferative activity (as assessed by Mib-1 immunolabelling, r=0.942, P<0.001) and the differentiation of sebaceous carcinoma of the eyelid (χ2=17.621, P<0.001), but not significantly related to tumor recurrence. The level of hTR expression increased with the decrease of differentiation of sebaceous carcinoma of the eyelid.Conclusions The results suggest that the up-regulation of telomerase expression plays some roles in tarsal gland carcinogenesis, and the expression of hTR is a useful marker for malignant degree of sebaceous carcinoma of the eyelid.

  17. Inhibition of Telomerase Activity of Lymphoblastic Leukemic Cells by hTERT Antisense

    Institute of Scientific and Technical Information of China (English)

    ZHANGYuan; LIWenyu

    2004-01-01

    To investigate the effect of antisense, human telomerase reverse transcriptase (hTERT) mRNA oligodeoxynucleotide on telomerase activity of lymphoblastic leukemic cells. Methods: Telomerase activity was measured by the telomerase PCR ELISA assay kit (TRAP), hTERT protein by immunochemistry and flowcytometry, hTERT mRNA expression by reverse transcription polymerase chain reaction (RT-PCR) assay and gel-image system. Results: Incubation of lymphoblastic leukemic cells (Jurkat, Raji and CEM cell lines) with 10 μmol/L AS PS-ODN could significantly decline the mRNA and hTERT after 72 h, and the telomerase activity was significantly down-regulated or inhibited. Conclusion: The hTERT AS PS-ODN was an excellent inhibitor for telomerase activity of lymphoblastic leukemic cells.

  18. Telomerase activity promotes osteoblast differentiation by modulating IGF-signaling pathway

    DEFF Research Database (Denmark)

    Saeed, Hamid; Qiu, Weimin; Chen, Li;

    2015-01-01

    The contribution of deficient telomerase activity to age-related decline in osteoblast functions and bone formation is poorly studied. We have previously demonstrated that telomerase over-expression led to enhanced osteoblast differentiation of human bone marrow skeletal (stromal) stem cells (h......MSC) in vitro and in vivo. Here, we investigated the signaling pathways underlying the regulatory functions of telomerase in osteoblastic cells. Comparative microarray analysis and Western blot analysis of telomerase-over expressing hMSC (hMSC-TERT) versus primary hMSC revealed significant up....... In addition, telomerase deficiency caused significant reduction in IGF signaling proteins in osteoblastic cells cultured from telomerase deficient mice (Terc (-/-)). The low bone mass exhibited by Terc (-/-) mice was associated with significant reduction in serum levels of IGF1 and IGFBP3 as well as...

  19. Improved Inhibition of Telomerase by Short Twisted Intercalating Nucleic Acids under Molecular Crowding Conditions

    DEFF Research Database (Denmark)

    Agarwal, Tani; Pradhan, Devranjan; Géci, Imrich;

    2012-01-01

    Human telomeric DNA has the ability to fold into a 4-stranded G-quadruplex structure. Several G-quadruplex ligands are known to stabilize the structure and thereby inhibit telomerase activity. Such ligands have demonstrated efficient telomerase inhibition in dilute conditions, but under molecular......-based telomerase repeat amplification assay (TRAP) assay as well as nondenaturing polyacrylamide gel electrophoresis-based TRAP, we demonstrate remarkable enhancement in their anti-telomerase activity even under molecular crowding conditions. This is the first time in which a G-quadruplex stabilizing agent has...

  20. Stem cell function and maintenance - ends that matter: Role of telomeres and telomerase

    Indian Academy of Sciences (India)

    Hamid Saeed; Mehwish Iqtedar

    2013-09-01

    Stem cell research holds a promise to treat and prevent age-related degenerative changes in humans. Literature is replete with studies showing that stem cell function declines with aging, especially in highly proliferative tissues/organs. Among others, telomerase and telomere damage is one of the intrinsic physical instigators that drive agerelated degenerative changes. In this review we provide brief overview of telomerase-deficient aging affects in diverse stem cells populations. Furthermore, potential disease phenotypes associated with telomerase dysregulation in a specific stem cell population is also discussed in this review. Additionally, the role of telomerase in stem cell driven cancer is also briefly touched upon.

  1. Human telomerase reverse-transcriptase promoter-controlled and herpes simplex virus thymidine kinase-armed adenoviruses for renal cell carcinoma treatment

    Directory of Open Access Journals (Sweden)

    Tian DW

    2013-04-01

    Full Text Available Dawei Tian,1–4 Yan Sun,3 Yang Yang,2,3 Mingde Lei,3 Na Ding,3 Ruifa Han2,31Tianjin Medical University, Tianjin, People's Republic of China; 2Department of Urinary Surgery, 3Tianjin Institute of Urology, Second Hospital of Tianjin Medical University, Tianjin, People's Republic of China; 4Tianjin Nankai Hospital, Tianjin, People's Republic of ChinaAbstract: New treatment strategies are required for renal cell carcinoma (RCC due to its relative insensitivity to conventional radio- and chemotherapies. The promising strategy of tumor inhibition using human telomerase reverse transcriptase (hTERT-controlled herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV in the hTERT promoter-driven HSV-TK/GCV suicide gene system was investigated. Tumor volume, weight, relative proliferation rate, and cell-apoptosis levels were examined in mice injected with adenovirus (Ad-hTERT-HSV-TK and GCV. Increased cell death occurred following treatment with Ads carrying hTERT-HSV-TK/GCV or cytomegalovirus promoter-controlled (CMV-HSV-TK/GCV for human RCC 786-0 and fibroblast MRC-5 cells. In mice, Ad-hTERT-HSV-TK/GCV more specifically inhibited tumor and RCC xenograft growth than Ad-CMV-HSV-TK/GCV (P < 0.05. Furthermore, Ad-hTERT-HSV-TK/GCV did not significantly damage normal fibroblasts or organ systems (heart, lung, liver, brain, kidney, and spleen. Thus, Ad-hTERT-HSV-TK/GCV is an effective RCC inhibitor in human cells in vitro and in vivo mouse models, indicating potential usefulness in RCC-targeted gene therapy.Keywords: hTERT promoter, HSV-TK/GCV, renal cell carcinoma, adenovirus

  2. miR-34a induces cellular senescence via modulation of telomerase activity in human hepatocellular carcinoma by targeting FoxM1/c-Myc pathway.

    Science.gov (United States)

    Xu, Xinsen; Chen, Wei; Miao, Runchen; Zhou, Yanyan; Wang, Zhixin; Zhang, Lingqiang; Wan, Yong; Dong, Yafeng; Qu, Kai; Liu, Chang

    2015-02-28

    Increasing evidence suggests that miRNAs can act as either tumor suppressors or oncogenes in carcinogenesis. In the present study, we identified the role of miR-34a in regulating telomerase activity, with subsequent effect on cellular senescence and viability. We found the higher expression of miR-34a was significantly correlated with the advanced clinicopathologic parameters in hepatocellular carcinoma. Furthermore, tumor tissues of 75 HCC patients demonstrated an inverse correlation between the miR-34a level and telomere indices (telomere length and telomerase activity). Transient introduction of miR-34a into HCC cell lines inhibited the telomerase activity and telomere length, which induced senescence-like phenotypes and affected cellular viability. We discovered that miR-34a potently targeted c-Myc and FoxM1, both of which were involved in the activation of telomerase reverse transcriptase (hTERT) transcription, essential for the sustaining activity of telomerase to avoid senescence. Taken together, our results demonstrate that miR-34a functions as a potent tumor suppressor through the modulation of telomere pathway in cellular senescence. PMID:25686834

  3. Properties of a Telomerase-Specific Cre/Lox Switch for Transcriptionally Targeted Cancer Gene Therapy

    Directory of Open Access Journals (Sweden)

    Alan E. Bilsland

    2005-11-01

    Full Text Available Telomerase expression represents a good target for cancer gene therapy. The promoters of the core telomerase catalytic [human telomerase reverse transcriptase (hTERT] and RNA [human telomerase RNA (hTR] subunits show selective activity in cancer cells but not in normal cells. This property can be harnessed to express therapeutic transgenes in a wide range of cancer cells. Unfortunately, weak hTR and hTERT promoter activities in some cancer cells could limit the target cell range. Therefore, strategies to enhance telomerasespecific gene therapy are of interest. We constructed a Cre/Lox reporter switch coupling telomerase promoter specificity with Cytomegalovirus (CMV promoter activity, which is generally considered to be constitutively high. In this approach, a telomerase-specific vector expressing Cre recombinase directs excisive recombination on a second vector, removing a transcriptional blockade to CMV-dependent luciferase expression. We tested switch activation in cell lines over a wide range of telomerase promoter activities. However, Cre/Lox-dependent luciferase expression was not enhanced relative to expression using hTR or hTERT promoters directly. Cell-specific differences between telomerase and CMV promoter activities and incomplete sigmoid switch activation were limiting factors. Notably, CMV activity was not always significantly stronger than telomerase promoter activity. Our conclusions provide a general basis for a more rational design of novel recombinase switches in gene therapy.

  4. Variations in telomere maintenance and the role of telomerase inhibition in gastrointestinal cancer

    Directory of Open Access Journals (Sweden)

    Heeg S

    2015-12-01

    Full Text Available Steffen Heeg Department of Medicine II, Gastroenterology, Hepatology, Endocrinology, and Infectious Diseases, Medical Center – University of Freiburg, Freiburg, Germany Abstract: Immortalization is an important step toward the malignant transformation of human cells and is critically dependent upon telomere maintenance. There are two known mechanisms to maintain human telomeres. The process of telomere maintenance is either mediated through activation of the enzyme telomerase or through an alternative mechanism of telomere lengthening called ALT. While 85% of all human tumors show reactivation of telomerase, the remaining 15% are able to maintain telomeres via ALT. The therapeutic potential of telomerase inhibitors is currently investigated in a variety of human cancers. Gastrointestinal tumors are highly dependent on telomerase as a mechanism of telomere maintenance, rendering telomeres as well as telomerase potential targets for cancer therapy. This article focuses on the molecular mechanisms of telomere biology and telomerase activation in gastrointestinal cancers and reviews strategies of telomerase inhibition and their potential therapeutic use in these tumor entities. Keywords: telomere based therapy, gastrointestinal cancer, telomere maintenance, telomerase inhibition

  5. Progress in structural studies of telomerase

    OpenAIRE

    Miracco, Edward J.; Jiang, Jiansen; Cash, Darian; Feigon, Juli

    2014-01-01

    Telomerase is the ribonucleoprotein (RNP) reverse transcriptase responsible for synthesizing the 3′ ends of linear chromosomes. It plays critical roles in tumorigenesis, cellular aging, and stem cell renewal. The past two years have seen exciting progress in determining telomerase holoenzyme architecture and the structural basis of telomerase activity. Notably, the first electron microscopy structures of telomerase were reported, of the Tetrahymena thermophila telomerase holoenzyme and a huma...

  6. A new fluorescence/PET probe for targeting intracellular human telomerase reverse transcriptase (hTERT) using Tat peptide-conjugated IgM.

    Science.gov (United States)

    Jung, Kyung Oh; Youn, Hyewon; Kim, Seung Hoo; Kim, Young-Hwa; Kang, Keon Wook; Chung, June-Key

    2016-08-26

    Despite an increasing need for methods to visualize intracellular proteins in vivo, the majority of antibody-based imaging methods available can only detect membrane proteins. The human telomerase reverse transcriptase (hTERT) is an intracellular target of great interest because of its high expression in several types of cancer. In this study, we developed a new probe for hTERT using the Tat peptide. An hTERT antibody (IgG or IgM) was conjugated with the Tat peptide, a fluorescence dye and (64)Cu. HT29 (hTERT+) and U2OS (hTERT-) were used to visualize the intracellular hTERT. The hTERT was detected by RT-PCR and western blot. Fluorescence signals for hTERT were obtained by confocal microscopy, live cell imaging, and analyzed by Tissue-FAXS. In nude mice, tumors were visualized using the fluorescence imaging devices Maestro™ and PETBOX. In RT-PCR and western blot, the expression of hTERT was detected in HT29 cells, but not in U2OS cells. Fluorescence signals were clearly observed in HT29 cells and in U2OS cells after 1 h of treatment, but signals were only detected in HT29 cells after 24 h. Confocal microscopy showed that 9.65% of U2OS and 78.54% of HT29 cells had positive hTERT signals. 3D animation images showed that the probe could target intranuclear hTERT in the nucleus. In mice models, fluorescence and PET imaging showed that hTERT in HT29 tumors could be efficiently visualized. In summary, we developed a new method to visualize intracellular and intranuclear proteins both in vitro and in vivo. PMID:27317485

  7. Targeting human telomeric G-quadruplex DNA and inhibition of telomerase activity with [(dmb2Ru(obipRu(dmb2](4+.

    Directory of Open Access Journals (Sweden)

    Shuo Shi

    Full Text Available Inhibition of telomerase by inducing/stabilizing G-quadruplex formation is a promising strategy to design new anticancer drugs. We synthesized and characterized a new dinuclear complex [(dmb2Ru(obipRu(dmb2](4+ (dmb = 4,4'-dimethyl-2,2'-bipyridine, obip = (2-(2-pyridylimidazo[4,5-f][1,10]phenanthroline with high affinity for both antiparallel and mixed parallel / antiparallel G-quadruplex DNA. This complex can promote the formation and stabilize G-quadruplex DNA. Dialysis and TRAP experiments indicated that [(dmb2Ru(obipRu(dmb2](4+ acted as an excellent telomerase inhibitor due to its obvious selectivity for G-quadruplex DNA rather than double stranded DNA. In vitro co-culture experiments implied that [(dmb2Ru(obipRu(dmb2](4+ inhibited telomerase activity and hindered cancer cell proliferation without side effects to normal fibroblast cells. TUNEL assay indicated that inhibition of telomerase activity induced DNA cleavage further apoptosis in cancer cells. Therefore, Ru(II complex represents an exciting opportunity for anticancer drug design by specifically targeting cancer cell G-quadruplexes DNA.

  8. RADIATION INDUCED PROGRESSIVE DECREASING IN THE EXPRESSION OF REVERSE TRANSCRIPTASE GENE OF hEST2 AND TELOMERASE ACTIVITY

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objectives. In order to identify the relationship between telomerase and the biological effect of radiation injury,and investigate the role of human telomerase catalytic subunit gene (hEST2) reverse transcriptase(RT) segment in the expression of telomerase activity. Methods. Tumor HeLa cells, KB cells and A431 cells were employed to measure the change in telomerase activity after 60Co ray irradiation at RNA level and protein level. Quantitative PCR and Northern blotting were used to determine the expression of hEST2 RT segment that encodes seven motifs of the human telomeres, a PCR based telomeric repeat amplification protocol (TRAP)was used to assay telomerase activity after exposure to radiation. Results. Both of telomerase activity and the expression hEST2 RT segment were decreased with increasing dosage of radiation. In addition, testing the expression of motifs domain is similar to the measurement of telomerase activity. Conclusion. The detection of the hEST2 RT segment by Northern blotting and quantitative PCR are new methods for testing telomerase activity. Furthermore, radiation can cause a dose dependent decrease in telomerase activity. The effect of radiation on telomerase is one possible reason for the death of cancer cells after irradiation.

  9. Identification of Telomerase-activating Blends From Naturally Occurring Compounds.

    Science.gov (United States)

    Ait-Ghezala, Ghania; Hassan, Samira; Tweed, Miles; Paris, Daniel; Crynen, Gogce; Zakirova, Zuchra; Crynen, Stefan; Crawford, Fiona

    2016-06-01

    Context • Telomeres are repeated deoxyribonucleic acid (DNA) sequences (TTAGGG) that are located on the 5' ends of chromosomes, and they control the life span of eukaryotic cells. Compelling evidence has shown that the length of a person's life is dictated by the limited number of times that a human cell can divide. The enzyme telomerase has been shown to bind to and extend the length of telomeres. Thus, strategies for activating telomerase may help maintain telomere length and, thus, may lead to improved health during aging. Objective • The current study intended to investigate the effects of several natural compounds on telomerase activity in an established cell model of telomere shortening (ie, IMR90 cells). Design • The research team designed an in vitro study. Setting • The study was conducted at Roskamp Institute in Sarasota, FL, USA. Intervention • The tested single compounds were (1) α-lipoic acid, (1) green tea extract, (2) dimethylaminoethanol L-bitartrate (DMAE L-bitartrate), (3) N-acetyl-L-cysteine hydrochloride (HCL), (4) chlorella powder, (5) L-carnosine, (6) vitamin D3, (7) rhodiola PE 3%/1%, (8) glycine, (9) French red wine extract, (10) chia seed extract, (11) broccoli seed extract, and (12) Astragalus (TA-65). The compounds were tested singly and as blends. Outcome Measures • Telomerase activity for single compounds and blends of compounds was measured by the TeloTAGGG telomerase polymerase chain reaction (PCR) enzyme-linked immunosorbent assay (ELISA). The 4 most potent blends were investigated for their effects on cancer-cell proliferation and for their potential effects on the cytotoxicity and antiproliferative activity of a chemotherapeutic agent, the topoisomerase I inhibitor topotecan. The benefits of 6 population doublings (PDs) were measured for the single compounds, and the 4 blends were compared to 3 concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Results • Certain of the compounds increased

  10. Effect of newly identified hTERT-interacting proteins on telomerase activity

    Institute of Scientific and Technical Information of China (English)

    Lina Zhou; Bing Chen; Xing Hua; Ping Zhou; Lian Guo; Yong Peng; Kunhua Qiu

    2013-01-01

    There is a close relationship between telomeres-telomerase and age-related disease.Human telomerase reverse transcriptase (hTERT) is both the catalytic component of human telomerase and the rate-limiting determinant of telomerase activity.Its transcriptional regulation is the primary mode of control of telomerase activity.It is critical to find the proteins interacting with hTERT for exploring the regulatory mechanisms of the hTERT expression and the telomerase activity.In this study,the yeast two-hybrid system was used to screen the potential interactive proteins of hTERT.Six proteins were obtained,among which TSTAR,LOXL3,HKR3,and Par-4 were further confirmed as the interacting proteins of hTERT by co-immunopreci-pitation.Then the sense and antisense gene eukaryotic expression vectors containing these four genes were constructed and transfected into tumor cell lines.The correlations among the expression levels of these four proteins,the expression level of hTERT,and the telomerase activity were analyzed.Results showed that the up-regulation of TSTAR expression and down-regulation of HKR3 expression led to the increase of hTERT expression and telomerase activity,while the up-and down-regulation of LOXL3 and Par-4 expressions had no obvious effect.Our results suggested that T-STAR has a positive correlation with the telomerase activity while HKR3 may be a negative regulator.This conclusion is important to further explore the influencing factors or regulation pathways of human telomerase activity,which may be of great importance for the potential clinical application.

  11. Telomerase-immortalized non-malignant human prostate epithelial cells retain the properties of multipotent stem cells

    International Nuclear Information System (INIS)

    Understanding prostate stem cells may provide insight into the origin of prostate cancer. Primary cells have been cultured from human prostate tissue but they usually survive only 15-20 population doublings before undergoing senescence. We report here that RC-170N/h/clone 7 cells, a clonal cell line from hTERT-immortalized primary non-malignant tissue-derived human prostate epithelial cell line (RC170N/h), retain multipotent stem cell properties. The RC-170N/h/clone 7 cells expressed a human embryonic stem cell marker, Oct-4, and potential prostate epithelial stem cell markers, CD133, integrin α2β1hi and CD44. The RC-170N/h/clone 7 cells proliferated in KGM and Dulbecco's Modified Eagle Medium with 10% fetal bovine serum and 5 μg/ml insulin (DMEM + 10% FBS + Ins.) medium, and differentiated into epithelial stem cells that expressed epithelial cell markers, including CK5/14, CD44, p63 and cytokeratin 18 (CK18); as well as the mesenchymal cell markers, vimentin, desmin; the neuron and neuroendocrine cell marker, chromogranin A. Furthermore the RC170 N/h/clone 7 cells differentiated into multi tissues when transplanted into the sub-renal capsule and subcutaneously of NOD-SCID mice. The results indicate that RC170N/h/clone 7 cells retain the properties of multipotent stem cells and will be useful as a novel cell model for studying the mechanisms of human prostate stem cell differentiation and transformation

  12. ARSENIC TRIOXIDE DOWNREGULATES TELOMERASE ACTIVITY IN HL-60 CELLS

    Institute of Scientific and Technical Information of China (English)

    何冬梅; 张洹

    2002-01-01

    Objective: To evaluate whether arsenic trioxide (AS2O3) could downregulate human telomerase reverse transcriptase (hTERT) gene expression and telomerase activity during induction of apoptosis of HL-60 cells. Methods: Apoptosis was detected by morphological observation and flow cytomertric cell cycle analysis. The expression of hTERT at mRNA and protein levels was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and immunofluorescence using fluoresce isothiocyanate (FITC) label, respectively. Telomerase activity was determined by polymerase chain reaction enzyme-linked immunoassay (PCR-ELISA). Results: Treatment of 2 μmol/L at As2O3 could induce apoptosis of HL-60 cells. hTERT was decreased at both mRNA and protein levels during apoptosis of HL-60 cells. Telomerase activity of HL-60 cells was significantly inhibited. Conclusion:It is suggested that telomerase activity of HL-60 cells might be specifically inhibited by AS2O3 through the downregulation of hTERT gene expression.

  13. Vaults and telomerase share a common subunit, TEP1.

    Science.gov (United States)

    Kickhoefer, V A; Stephen, A G; Harrington, L; Robinson, M O; Rome, L H

    1999-11-12

    Vaults are large cytoplasmic ribonucleoprotein complexes of undetermined function. Mammalian vaults have two high molecular mass proteins of 193 and 240 kDa. We have identified a partial cDNA encoding the 240-kDa vault protein and determined it is identical to the mammalian telomerase-associated component, TEP1. TEP1 is the mammalian homolog of the Tetrahymena p80 telomerase protein and has been shown to interact specifically with mammalian telomerase RNA and the catalytic protein subunit hTERT. We show that while TEP1 is a component of the vault particle, vaults have no detectable telomerase activity. Using a yeast three-hybrid assay we demonstrate that several of the human vRNAs interact in a sequence-specific manner with TEP1. The presence of 16 WD40 repeats in the carboxyl terminus of the TEP1 protein is a convenient number for this protein to serve a structural or organizing role in the vault, a particle with eight-fold symmetry. The sharing of the TEP1 protein between vaults and telomerase suggests that TEP1 may play a common role in some aspect of ribonucleoprotein structure, function, or assembly. PMID:10551828

  14. miR-34a induces cellular senescence via modulation of telomerase activity in human hepatocellular carcinoma by targeting FoxM1/c-Myc pathway

    OpenAIRE

    Xu, Xinsen; Chen, Wei; Miao, Runchen; Zhou, Yanyan; Wang, Zhixin; Zhang, Lingqiang; Wan, Yong; Dong, Yafeng; Qu, Kai; Liu, Chang

    2015-01-01

    Increasing evidence suggests that miRNAs can act as either tumor suppressors or oncogenes in carcinogenesis. In the present study, we identified the role of miR-34a in regulating telomerase activity, with subsequent effect on cellular senescence and viability. We found the higher expression of miR-34a was significantly correlated with the advanced clinicopathologic parameters in hepatocellular carcinoma. Furthermore, tumor tissues of 75 HCC patients demonstrated an inverse correlation between...

  15. Progressive Increase in Telomerase Activity From Benign Melanocytic Conditions to Malignant Melanoma

    Directory of Open Access Journals (Sweden)

    Ruben D. Ramirez

    1999-04-01

    Full Text Available The expression of telomerase activity and the in situ localization of the human telomerase RNA component (hTR in melanocytic skin lesions was evaluated in specimens from sixty-three patients. Specimens of melanocytic nevi, primary melanomas and subcutaneous metastases of melanoma were obtained from fifty-eight patients, whereas metastasized lymph nodes were obtained from five patients. Telomerase activity was determined in these specimens by using a Polymerase Chain Reaction—based assay (TRAP. High relative mean telomerase activity levels were detected in metastatic melanoma (subcutaneous metastasess = 54.5, lymph node metastasess = 56.5. Much lower levels were detected in primary melanomas, which increased with advancing levels of tumor cell penetration (Clark II = 0.02, Clark III = 1.1, and Clark IV = 1.9. Twenty-six formalin-fixed, paraffin-embedded melanocytic lesions were sectioned and analyzed for telomerase RNA with a radioactive in situ hybridization assay. In situ hybridization studies with a probe to the template RNA component of telomerase confirmed that expression was almost exclusively confined to tumor cells and not infiltrating lymphocytes. These results indicate that levels of telomerase activity and telomerase RNA in melanocytic lesions correlate well with clinical stage and could potentially assist in the diagnosis of borderline lesions.

  16. Mapping of the Gene for the Human Telomerase Reverse Transcriptase, hTERT, to Chromosome 5p15.33 by Fluorescence in Situ Hybridization

    Directory of Open Access Journals (Sweden)

    Lisa A. Bryce

    2000-05-01

    Full Text Available Telomerase, the enzyme that maintains the ends of chromosomes, is absent from the majority of somatic cells but is present and active in most tumours. The gene for the reverse transcriptase component of telomerase (hTERT has recently been identified. A cDNA clone of this gene was used as a probe to identify three genomic bacterial artificial chromosome (BAC clones, one of which was used as a probe to map hTERT by fluorescence in situ hybridization (FISH to chromosome 5p15.33. This BAC probe was further used to look at copy number of the hTERT region in immortal cell lines. We found that 10/15 immortal cell lines had a modal copy number of 3 or more per cell, with one cell line (CaSki having a modal copy number of 11. This suggests that increases in copy number of the hTERT gene region do occur, and may well be one route to upregulating telomerase levels in tumour cells. 5p15 gains and amplifications have been documented for various tumour types, including non-small cell lung carcinoma, squamous cell carcinoma of head and neck, and uterine cervix cancer, making hTERT a potential target.

  17. Telomerase activation after recruitment in fission yeast.

    OpenAIRE

    Armstrong, C. A.; Pearson, S R; Amelina, H.; Moiseeva, V.; Tomita, K.

    2014-01-01

    Summary Current models depict that telomerase recruitment equates to activation. Telomeric DNA-binding proteins and the telomerase accessory proteins coordinate the recruitment of telomerase to the ends of chromosomes in a telomere length- and cell-cycle-dependent manner [1–4]. Recent studies have demonstrated that the telomeric protein TPP1 and its binding protein TIN2 are key proteins for both telomerase recruitment and processivity in mammalian cells [5–7]. Although the precise molecular m...

  18. Telomerase activity in plasma cell dyscrasias

    OpenAIRE

    Xu, D; Zheng, C.; Bergenbrant, S; Holm, G; Björkholm, M.; Yi, Q; Gruber, A

    2001-01-01

    Activation of telomerase is essential for in vitro cellular immortalization and tumorigenesis. In the present study, we investigated telomerase activation and its implications in plasma cell dyscrasias including monoclonal gammopathy of undetermined significance (MGUS), multiple myeloma (MM) and plasma cell leukaemia (PCL). All 5 patients with MGUS exhibited normal levels of telomerase activity in their plasma cells. Elevated telomerase activity was found in the samples from 21/27 patients wi...

  19. Ionizing Radiation Promotes Migration and Invasion of Cancer Cells Through Transforming Growth Factor-Beta-Mediated Epithelial-Mesenchymal Transition

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Yongchun [Department of Radiation Oncology, Xijing Hospital Fourth Military Medical University, Xi' an (China); Department of Radiation Medicine, College of Preventive Medicine, Xijing Hospital Fourth Military Medical University, Xi' an (China); Liu Junye; Li Jing; Zhang Jie [Department of Radiation Medicine, College of Preventive Medicine, Xijing Hospital Fourth Military Medical University, Xi' an (China); Xu Yuqiao [Department of Pathology, Xijing Hospital Fourth Military Medical University, Xi' an (China); Zhang Huawei; Qiu Lianbo; Ding Guirong [Department of Radiation Medicine, College of Preventive Medicine, Xijing Hospital Fourth Military Medical University, Xi' an (China); Su Xiaoming [Department of Radiation Oncology, 306th Hospital of PLA, Beijing (China); Mei Shi [Department of Radiation Oncology, Xijing Hospital Fourth Military Medical University, Xi' an (China); Guo Guozhen, E-mail: guozhenguo@hotmail.com [Department of Radiation Medicine, College of Preventive Medicine, Xijing Hospital Fourth Military Medical University, Xi' an (China)

    2011-12-01

    Purpose: To examine whether ionizing radiation enhances the migratory and invasive abilities of cancer cells through transforming growth factor (TGF-{beta})-mediated epithelial-mesenchymal transition (EMT). Methods and Materials: Six cancer cell lines originating from different human organs were irradiated by {sup 60}Co {gamma}-ray at a total dose of 2 Gy, and the changes associated with EMT, including morphology, EMT markers, migration and invasion, were observed by microscope, Western blot, immunofluorescence, scratch assay, and transwell chamber assay, respectively. Then the protein levels of TGF-{beta} in these cancer cells were detected by enzyme-linked immunosorbent assay, and the role of TGF-{beta} signaling pathway in the effect of ionizing radiation on EMT was investigate by using the specific inhibitor SB431542. Results: After irradiation with {gamma}-ray at a total dose of 2 Gy, cancer cells presented the mesenchymal phenotype, and compared with the sham-irradiation group the expression of epithelial markers was decreased and of mesenchymal markers was increased, the migratory and invasive capabilities were strengthened, and the protein levels of TGF-{beta} were enhanced. Furthermore, events associated with EMT induced by IR in A549 could be reversed through inhibition of TGF-{beta} signaling. Conclusions: These results suggest that EMT mediated by TGF-{beta} plays a critical role in IR-induced enhancing of migratory and invasive capabilities in cancer cells.

  20. Cycloastragenol Is a Potent Telomerase Activator in Neuronal Cells: Implications for Depression Management

    Directory of Open Access Journals (Sweden)

    Fanny C.F. Ip

    2014-07-01

    Full Text Available Cycloastragenol (CAG is an aglycone of astragaloside IV. It was first identified when screening Astragalus membranaceus extracts for active ingredients with antiaging properties. The present study demonstrates that CAG stimulates telomerase activity and cell proliferation in human neonatal keratinocytes. In particular, CAG promotes scratch wound closure of human neonatal keratinocyte monolayers in vitro. The distinct telomerase-activating property of CAG prompted evaluation of its potential application in the treatment of neurological disorders. Accordingly, CAG induced telomerase activity and cAMP response element binding (CREB activation in PC12 cells and primary neurons. Blockade of CREB expression in neuronal cells by RNA interference reduced basal telomerase activity, and CAG was no longer efficacious in increasing telomerase activity. CAG treatment not only induced the expression of bcl2, a CREB-regulated gene, but also the expression of telomerase reverse transcriptase in primary cortical neurons. Interestingly, oral administration of CAG for 7 days attenuated depression-like behavior in experimental mice. In conclusion, CAG stimulates telomerase activity in human neonatal keratinocytes and rat neuronal cells, and induces CREB activation followed by tert and bcl2 expression. Furthermore, CAG may have a novel therapeutic role in depression. © 2014 S. Karger AG, Basel

  1. Telomerase targeting in cancer treatment : new developments

    NARCIS (Netherlands)

    Helder, MN; de Jong, S; de Vries, EGE; van der Zee, AGJ

    1999-01-01

    Telomerase, a ribonucleoprotein expressed in 85% of advanced cancers but not in most somatic cells, compensates for telomeric DNA erosion and as such stabilizes cell immortality. Telomerase inhibition might restore mortality in tumor cells. Recent progress is illustrated in studies on telomerase and

  2. Telomerase activates transcription of cyclin D1 gene through an interaction with NOL1.

    Science.gov (United States)

    Hong, Juyeong; Lee, Ji Hoon; Chung, In Kwon

    2016-04-15

    Telomerase is a ribonucleoprotein enzyme that is required for the maintenance of telomere repeats. Although overexpression of telomerase in normal human somatic cells is sufficient to overcome replicative senescence, the ability of telomerase to promote tumorigenesis requires additional activities that are independent of its role in telomere extension. Here, we identify proliferation-associated nucleolar antigen 120 (NOL1, also known as NOP2) as a telomerase RNA component (TERC)-binding protein that is found in association with catalytically active telomerase. Although NOL1 is highly expressed in the majority of human tumor cells, the molecular mechanism by which NOL1 contributes to tumorigenesis remained unclear. We show that NOL1 binds to the T-cell factor (TCF)-binding element of the cyclin D1 promoter and activates its transcription. Interestingly, telomerase is also recruited to the cyclin D1 promoter in a TERC-dependent manner through the interaction with NOL1, further enhancing transcription of the cyclin D1 gene. Depletion of NOL1 suppresses cyclin D1 promoter activity, thereby leading to induction of growth arrest and altered cell cycle distributions. Collectively, our findings suggest that NOL1 represents a new route by which telomerase activates transcription of cyclin D1 gene, thus maintaining cell proliferation capacity. PMID:26906424

  3. Diagnosis of pancreatic cancer by cytology and telomerase activity in exfoliated cells obtained by pancreatic duct brushing during endoscopy

    Institute of Scientific and Technical Information of China (English)

    Guo-Xiong Zhou; Jie-Fei Huang; Hong Zhang; Jian-Ping Chen

    2007-01-01

    BACKGROUND:Telomerase activity is reported to be speciifc and frequent in human pancreatic cancer. We conducted this study to assess the usefulness of monitoring telomerase activity in exfoliated cells obtained by pancreatic duct brushing during endoscopic retrograde cholangiopancreatography (ERCP) for the diagnosis of pancreatic cancer. METHODS:Exfoliated cells obtained by pancreatic duct brushing during ERCP from 21 patients (18 with pancreatic cancer, 3 with chronic pancreatitis) were examined. Telomerase activity was detected by polymerase chain reaction and telomeric repeat ampliifcation protocol assay (PCR-TRAP-ELISA). RESULTS:D450 values of telomerase activity were 0.446± 0.2700 in pancreatic cancer and 0.041±0.0111 in chronic pancreatitis. 77.8% (14/18) of patients with pancreatic cancer had cells with telomerase activity. None of the samples from patients with chronic pancreatitis showed telomerase activity, when the cutoff value of telomerase activity was set at 2.0. Cytological examination showed cancer cells in 66.7%(12/18) of the patients. CONCLUSIONS:Telomerase activity may be an early malignant event in pancreatic cancer development. Cytology and telomerase activity in cells obtained by pancreatic duct brushing may complement each other for the diagnosis of pancreatic cancer.

  4. Detection of Telomerase Activity Using Capacitance Measurements

    Science.gov (United States)

    Kang, Bong Keun; Lee, Ri Mi; Choi, Ahmi; Jung, Hyo-Il; Yoo, Kyung-Hwa

    2007-03-01

    Telomerase activity has been found in about 85% cancer cells, while no activity observed in normal cells, so that telomerase has been proposed as a marker for cancer detection. Here, we describe electrical detection of telomerase activity using capacitance measurements. We have investigated the length dependence of capacitance on DNA solutions and found that the capacitance of DNA solutions were dependent on the DNA length. In addition, upon adding telomerase into the solution of telomeric substrate primer, the capacitance was observed to change as a function of time due to the telomeric elongation. These results suggest that this novel nanosensor may be used for rapid detection of telomerase activity.

  5. The TEL patch of telomere protein TPP1 mediates telomerase recruitment and processivity

    OpenAIRE

    Nandakumar, Jayakrishnan; Bell, Caitlin F.; Weidenfeld, Ina; Zaug, Arthur J.; Leinwand, Leslie A.; Cech, Thomas R.

    2012-01-01

    Human chromosome ends are capped by shelterin, a protein complex that protects the natural ends from being recognized as sites of DNA damage and also regulates the telomere-replicating enzyme, telomerase 1–3 . Shelterin includes the heterodimeric POT1-TPP1 protein, which binds the telomeric single-stranded DNA tail 4–9 . TPP1 has been implicated both in recruiting telomerase to telomeres and in stimulating telomerase processivity (the addition of multiple DNA repeats after a single primer-bin...

  6. DETECTION OF TELOMERASE ACTIVITY IN BREAST CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    Yang Wentao; Xu Liangzhong; Zhang Taiming; Zhu weiping; Li Xiaomei; Jin Aiping

    1998-01-01

    Objective:To investigate the significance of telomerase activity in breast carcinoma with its respect to axillary lymph node status. Methods: Telomerase activity was analyzed in 88 breast carcinomas and 16benign breast lesions, using polymerase chain reaction (PCR)-based telomeric repeat amplification protocol (TRAP) assay. Results: Telomerase activity was detected in 75 (85%) of 88 breast carcinomas (including three breast carcinomas in situ which were all positive for telomerase activity), whereas in benign breast lesions analyzed only 2(12.5%) of 16 cases were positive for telomerase activity. The difference between the two groups was statistically significant (P<0.001). Besides,telomerase activity was expressed significantly higher in node-positive breast carcinoma (93%) than in nodenegative ones (77%) (P<0.05). Conclusion: Our results suggest that telomerase activation plays an important role during breast carcinoma development. It is possible that this enzyme may serve as an early indication of breast carcinoma.

  7. Regulation of the Telomerase Reverse Transcriptase Subunit through Epigenetic Mechanisms

    Science.gov (United States)

    Lewis, Kayla A.; Tollefsbol, Trygve O.

    2016-01-01

    Chromosome-shortening is characteristic of normal cells, and is known as the end replication problem. Telomerase is the enzyme responsible for extending the ends of the chromosomes in de novo synthesis, and occurs in germ cells as well as most malignant cancers. There are three subunits of telomerase: human telomerase RNA (hTERC), human telomerase associated protein (hTEP1), or dyskerin, and human telomerase reverse transcriptase (hTERT). hTERC and hTEP1 are constitutively expressed, so the enzymatic activity of telomerase is dependent on the transcription of hTERT. DNA methylation, histone methylation, and histone acetylation are basic epigenetic regulations involved in the expression of hTERT. Non-coding RNA can also serve as a form of epigenetic control of hTERT. This epigenetic-based regulation of hTERT is important in providing a mechanism for reversibility of hTERT control in various biological states. These include embryonic down-regulation of hTERT contributing to aging and the upregulation of hTERT playing a critical role in over 90% of cancers. Normal human somatic cells have a non-methylated/hypomethylated CpG island within the hTERT promoter region, while telomerase-positive cells paradoxically have at least a partially methylated promoter region that is opposite to the normal roles of DNA methylation. Histone acetylation of H3K9 within the promoter region is associated with an open chromatin state such that transcription machinery has the space to form. Histone methylation of hTERT has varied control of the gene, however. Mono- and dimethylation of H3K9 within the promoter region indicate silent euchromatin, while a trimethylated H3K9 enhances gene transcription. Non-coding RNAs can target epigenetic-modifying enzymes, as well as transcription factors involved in the control of hTERT. An epigenetics diet that can affect the epigenome of cancer cells is a recent fascination that has received much attention. By combining portions of this diet with

  8. Ticking Telomeres/Telltale Telomerase.

    Science.gov (United States)

    Biermann, Carol A.

    1997-01-01

    Discusses telomeres, complexes of DNA and protein that form the chromatin at the ends of chromosomes. Highlights telomeres as controllers of chromosome integrity, expendable telomeres, DNA replication requirements and their consequences, protection of structural genes, telomerase as indicators of immortality, cancer cells and other immortals, and…

  9. A Cajal body-independent pathway for telomerase trafficking in mice

    Energy Technology Data Exchange (ETDEWEB)

    Tomlinson, Rebecca L.; Li, Jian; Culp, Bradley R.; Terns, Rebecca M., E-mail: rterns@bmb.uga.edu; Terns, Michael P., E-mail: mterns@bmb.uga.edu

    2010-10-15

    The intranuclear trafficking of human telomerase involves a dynamic interplay between multiple nuclear sites, most notably Cajal bodies and telomeres. Cajal bodies are proposed to serve as sites of telomerase maturation, storage, and assembly, as well as to function in the cell cycle-regulated delivery of telomerase to telomeres in human cells. Here, we find that telomerase RNA does not localize to Cajal bodies in mouse cells, and instead resides in separate nuclear foci throughout much of the cell cycle. However, as in humans, mouse telomerase RNA (mTR) localizes to subsets of telomeres specifically during S phase. The localization of mTR to telomeres in mouse cells does not require coilin-containing Cajal bodies, as mTR is found at telomeres at similar frequencies in cells from wild-type and coilin knockout mice. At the same time, we find that human TR localizes to Cajal bodies (as well as telomeres) in mouse cells, indicating that the distinct trafficking of mTR is attributable to an intrinsic property of the RNA (rather than a difference in the mouse cell environment such as the properties of mouse Cajal bodies). We also find that during S phase, mTR foci coalesce into short chains, with at least one of the conjoined mTR foci co-localizing with a telomere. These findings point to a novel, Cajal body-independent pathway for telomerase biogenesis and trafficking in mice.

  10. A Cajal body-independent pathway for telomerase trafficking in mice

    International Nuclear Information System (INIS)

    The intranuclear trafficking of human telomerase involves a dynamic interplay between multiple nuclear sites, most notably Cajal bodies and telomeres. Cajal bodies are proposed to serve as sites of telomerase maturation, storage, and assembly, as well as to function in the cell cycle-regulated delivery of telomerase to telomeres in human cells. Here, we find that telomerase RNA does not localize to Cajal bodies in mouse cells, and instead resides in separate nuclear foci throughout much of the cell cycle. However, as in humans, mouse telomerase RNA (mTR) localizes to subsets of telomeres specifically during S phase. The localization of mTR to telomeres in mouse cells does not require coilin-containing Cajal bodies, as mTR is found at telomeres at similar frequencies in cells from wild-type and coilin knockout mice. At the same time, we find that human TR localizes to Cajal bodies (as well as telomeres) in mouse cells, indicating that the distinct trafficking of mTR is attributable to an intrinsic property of the RNA (rather than a difference in the mouse cell environment such as the properties of mouse Cajal bodies). We also find that during S phase, mTR foci coalesce into short chains, with at least one of the conjoined mTR foci co-localizing with a telomere. These findings point to a novel, Cajal body-independent pathway for telomerase biogenesis and trafficking in mice.

  11. TELOMERASE ACTIVITY AND hTERT mRNA EXPRESSION IN ACUTE LEUKEMIA

    Institute of Scientific and Technical Information of China (English)

    何冬梅; 张洹

    2004-01-01

    Objective: To investigate the clinical implications of telomerase activity and human telomerase reverse transcriptase (hTERT) expression as useful diagnostic marker in acute leukemia. Methods: Expression of hTERT was detected by reverse transcription- polymerase chain reaction (RT-PCR) in 24 cases with acute leukemia and in 12 normal persons. Quantitative levels of telomerase activity were examined by polymerase chain reaction enzyme-linked immunoassay (PCR-ELISA). Results: In the bone marrow and peripheral blood of 24 acute leukemia, telomerase activity was detected in 75% of the samples, with absorbances (A) of 0.538(0.062 and 0.463(0.054, respectively. Whereas in 12 normal peripheral blood, telomerase activity had only a positive rate of 8.3%, with A value of 0.16(0.012. telomerase activities in the bone marrow and peripheral blood of acute leukemia were significantly higher than in normal control (P<0.05). RT-PCR analysis revealed that hTERT mRNA was expressed in 79.17%(19/24) of acute leukemia, but in only 1 of 12 normal peripheral blood. In 24 acute leukemias, 17 cases had both positive telomerse activity and hTERT mRNA expression. The expression of hTERT mRNA is correlated with telomerase activity (P<0.01). Conclusion: Telomerase and hTERT mRNA could be useful in diagnosis of acute leukemia. hTERT gene expression was strongly associated with telomerase activity in acute leukemia.

  12. RADIATION-INDUCED PROGRESSIVE DECREASINGIN THE EXPRESSION OF REVERSE TRANSCRIPTASE GENE OF hEST2 AND TELOMERASE ACTIVITY

    Institute of Scientific and Technical Information of China (English)

    朱涵能; 熊思东; 程文英

    2001-01-01

    Objectites. In order to identify the relationship between telomerase and the biological effect of radiation injury, and investigate the role of human telomerase catalytic subunit gene (hEST2) reverse tranacriptase(RT) seg-ment in the expression of telomerase activity. Methods. Tumor FIeLa cells, KB cells and A431 cells were employed to measure the change in telomeraseactivity after 60Co-ray irradiation at RNA level and protein level. Quantitative PCR and Northern blotting wereused to determine the expression of bEST2 RT segment that encodes seven motifs of the human telomeres, a PCR-besed telomeric repeat amplification protocol (TRAP)was used to assay telomerase activity after exposure toradiation. Results. Both of telomerase activity and the expression hEST2 RT segment were decreased with increasingdosage of radiation. In addition, testing the expression of motifs domain is similar to the measurement of telomerase activity. Conclusion. The detection of the hEST2 BT segment by Northern blotting and quantitative PCR are new methods for testing Uflomerase activity. Furthermore, radiation can cause a dose-dependent decrease in telomerase activity. The effect of radiation on telomerase is one possible reason for the death of cancer ceils after irradiation.

  13. Structure of the Tribolium castaneum Telomerase Catalytic Subunit TERT

    Energy Technology Data Exchange (ETDEWEB)

    Gillis,A.; Schuller, A.; Skordalakes, E.

    2008-01-01

    A common hallmark of human cancers is the overexpression of telomerase, a ribonucleoprotein complex that is responsible for maintaining the length and integrity of chromosome ends. Telomere length deregulation and telomerase activation is an early, and perhaps necessary, step in cancer cell evolution. Here we present the high-resolution structure of the Tribolium castaneum catalytic subunit of telomerase, TERT. The protein consists of three highly conserved domains, organized into a ring-like structure that shares common features with retroviral reverse transcriptases, viral RNA polymerases and B-family DNA polymerases. Domain organization places motifs implicated in substrate binding and catalysis in the interior of the ring, which can accommodate seven to eight bases of double-stranded nucleic acid. Modelling of an RNA-DNA heteroduplex in the interior of this ring demonstrates a perfect fit between the protein and the nucleic acid substrate, and positions the 3'-end of the DNA primer at the active site of the enzyme, providing evidence for the formation of an active telomerase elongation complex.

  14. Vault poly(ADP-ribose) polymerase is associated with mammalian telomerase and is dispensable for telomerase function and vault structure in vivo.

    Science.gov (United States)

    Liu, Yie; Snow, Bryan E; Kickhoefer, Valerie A; Erdmann, Natalie; Zhou, Wen; Wakeham, Andrew; Gomez, Marla; Rome, Leonard H; Harrington, Lea

    2004-06-01

    Vault poly(ADP-ribose) polymerase (VPARP) was originally identified as a minor protein component of the vault ribonucleoprotein particle, which may be involved in molecular assembly or subcellular transport. In addition to the association of VPARP with the cytoplasmic vault particle, subpopulations of VPARP localize to the nucleus and the mitotic spindle, indicating that VPARP may have other cellular functions. We found that VPARP was associated with telomerase activity and interacted with exogenously expressed telomerase-associated protein 1 (TEP1) in human cells. To study the possible role of VPARP in telomerase and vault complexes in vivo, mVparp-deficient mice were generated. Mice deficient in mVparp were viable and fertile for up to five generations, with no apparent changes in telomerase activity or telomere length. Vaults purified from mVparp-deficient mouse liver appeared intact, and no defect in association with other vault components was observed. Mice deficient in mTep1, whose disruption alone does not affect telomere function but does affect the stability of vault RNA, showed no additional telomerase or telomere-related phenotypes when the mTep1 deficiency was combined with an mVparp deficiency. These data suggest that murine mTep1 and mVparp, alone or in combination, are dispensable for normal development, telomerase catalysis, telomere length maintenance, and vault structure in vivo. PMID:15169895

  15. Telomerase Holoenzyme Proteins and Processivity Subunit in Tetrahymena thermophila

    OpenAIRE

    Min, Bosun

    2009-01-01

    Telomeres are specialized protein-DNA structures that protect the ends of linear chromosomes, and they are maintained by the telomerase ribonucleoprotein (RNP) enzyme complex. Recombinant telomerase RNP with catalytic activity contains, at a minimum, the catalytic reverse transcriptase subunit (TERT) and the telomerase RNA (TER). However, endogenous telomerase is a much larger holoenzyme complex, with telomerase-associated subunits that contribute to RNP assembly and regulation. Telomerase-as...

  16. Extracting Extra-Telomeric Phenotypes from Telomerase Mouse Models

    OpenAIRE

    Sung, Young Hoon; Ali, Muhammad; Lee, Han-Woong

    2013-01-01

    Telomerase reverse transcriptase (TERT) is the protein component of telomerase and combined with an RNA molecule, telomerase RNA component, forms the telomerase enzyme responsible for telomere elongation. Telomerase is essential for maintaining telomere length from replicative attrition and thus contributes to the preservation of genome integrity. Although diverse mouse models have been developed and studied to prove the physiological roles of telomerase as a telomere-elongating enzyme, recen...

  17. Telomerase activity in germline and embryonic cells of Xenopus.

    OpenAIRE

    Mantell, L L; Greider, C W

    1994-01-01

    Telomerase is a ribonucleoprotein which synthesizes telomere repeats onto chromosome ends. Telomerase activity is involved in telomere length maintenance. We used Xenopus laevis as a model system to study the expression of telomerase activity in germline cells and during early development. We identified a non-processive telomerase activity in manually dissected nuclei of Xenopus stage VI oocytes. Telomerase activity was detected throughout oogenesis and embryogenesis. Telomerase was active in...

  18. Absence of telomerase activity and telomerase catalytic subunit mRNA in melanocyte cultures

    OpenAIRE

    Dhaene, K.; Vancoillie, G; Lambert, J.; Naeyaert, J M; Van Marck, E

    2000-01-01

    The classic model of activation of telomerase, for which activity has been found in most cancers including cutaneous malignant melanoma (CMM), dictates that enzyme activity is generated by pathological reactivation of telomerase in telomerase-negative somatic cells. However, recent data demonstrated physiological up-regulation in some normal cell types when established as proliferating cultures, indicating that, in some cancer types, telomerase is expressed by the process of up-regulation in ...

  19. ASSAYS FOR DETECTION OF TELOMERASE ACTIVITY

    OpenAIRE

    Skvortsov, D.; Zvereva, M.; Shpanchenko, O.; Dontsova, O.

    2011-01-01

    Progressive loss of the telomeric ends of chromosomes caused by the semi-conservative mechanism of DNA replication is an important timing mechanism which controls the number of cells doubling. Telomerase is an enzyme which elongates one chain of the telomeric DNA and compensates for its shortening during replication. Therefore, telomerase activity serves as a proliferation marker. Telomerase activity is not detected in most somatic cells, with the exception of embryonic tissues, stem cells, a...

  20. Differentiation of immortal cells inhibits telomerase activity.

    OpenAIRE

    Sharma, H W; Sokoloski, J A; Perez, J.R.; Maltese, J Y; Sartorelli, A C; Stein, C A; Nichols, G; Khaled, Z.; Telang, N T; Narayanan, R.

    1995-01-01

    Telomerase, a ribonucleic acid-protein complex, adds hexameric repeats of 5'-TTAGGG-3' to the ends of mammalian chromosomal DNA (telomeres) to compensate for the progressive loss that occurs with successive rounds of DNA replication. Although somatic cells do not express telomerase, germ cells and immortalized cells, including neoplastic cells, express this activity. To determine whether the phenotypic differentiation of immortalized cells is linked to the regulation of telomerase activity, t...

  1. Progressive telomere shortening and telomerase reactivation during hepatocellular carcinogenesis.

    Science.gov (United States)

    Miura, N; Horikawa, I; Nishimoto, A; Ohmura, H; Ito, H; Hirohashi, S; Shay, J W; Oshimura, M

    1997-01-01

    Telomeres shorten progressively with age in normal somatic cells in culture and in vivo. The maintenance of telomere length is assumed to be an obligatory step in the progression and immortalization of most human tumor cells. To understand the role of telomere dynamics in the development of hepatocellular carcinoma (HCC), we examined the length of terminal restriction fragment (TRF), as an indicator for telomere length, in HCC and surrounding tissues with chronic active hepatitis (CAH) or liver cirrhosis (LC). The study was performed in 12 hepatitis C virus (HCV) antibody-positive, 12 hepatitis B virus (HBV) antigen-positive tissues, and 4 tissue samples from virus-negative patients with HCC. The peak TRFs in all 3 types of HCC were significantly shorter than those of the surrounding tissues (i.e., LC or CAH). TRFs examined in one patient with atypical adenomatous hyperplasia (AAH) also was shortened. Thus, progressive TRF shortening occurs from normal to CAH to LC to HCC(AAH). Telomerase, an enzyme that adds repeated telomere sequences onto the chromosome ends and stabilizes telomere length in immortal cells, also was examined in tissues and detected in high levels almost exclusively in HCCs. Interestingly, the intensity of telomerase activity in the AAH case was similar to that of HCC. In addition, the telomerase activity of biopsy samples with a fine 21-gauge needle also was examined in 10 HCCs, 2 adenomatous hyperplasias (AHs), 2 LCs, and 2 CAHs. We found strong telomerase activity in all the HCCs and surprisingly in the 2 cases that were pathologically diagnosed as AH. Thus, the findings strongly suggest that persistent cell proliferation or rapid cell turnover through damage of hepatic cells result in a process of multistep hepatocellular carcinogenesis. Thus, progressive shortening of telomeres and the activation of telomerase may be a useful marker for the early detection of malignant progression in liver disease. PMID:9062581

  2. Role of GLTSCR2 in the regulation of telomerase activity and chromosome stability.

    Science.gov (United States)

    Kim, Jee-Youn; An, Yong-Min; Park, Jae-Hoon

    2016-08-01

    Telomerase is essential for regulating telomeres, and its activation is a critical step in cellular immortalization and tumorigenesis. The transcriptional activation of human telomerase reverse transcriptase (hTERT) is critical for telomerase expression. Although several transcriptional activators have been identified, factors responsible for enhancing the hTERT promoter remain to be fully elucidated. In the present study, the role of glioma tumor-suppressor candidate region gene 2 (GLTSCR2) in telomerase regulation was analyzed. A doxycyclin-inducible green fluorescent protein (GFP)-tagged GLTSCR2-expressing adenovirus (Ad‑GLT/GFP) was used for the transduction of SK‑Hep‑1 and T98G cancer cells, and normal human umbilical vein endothelial cells. Changes in telomerase activity using telomere repeat amplification protocol assay were assessed, and the gene expression levels of hTERT were then examined. To investigate chromosome instability and senescence, Giemsa and β-galactosidase staining was performed. The results revealed that overexpression of GLTSCR2 significantly increased telomerase activity in the cancer and normal cell lines. This increase was consistent with increases in the protein and mRNA expression levels of hTERT. In luciferase assays, the hTERT promoter was activated by GLTSCR2. Knockdown of GLTSCR2 led to the downregulation of telomerase activity, abnormal nuclear morphology as a marker of chromosome instability, significant suppression of growth rate, alterations in cellular morphology and, eventually, cellular senescence. Taken together, the results of the present study suggested that GLTSCR2 is crucially involved in the positive regulation of telomerase and chromosome stability. PMID:27357325

  3. Molecular regulation of telomerase activity in aging

    Institute of Scientific and Technical Information of China (English)

    Craig Nicholls; He Li; Jian-Qiu Wang; Jun-Ping Liu

    2011-01-01

    The process of aging is mitigated by the maintenance and repair of chromosome ends (telomeres),resulting in extended lifespan.This review examines the molecular mechanisms underlying the actions and regulation of the enzyme telomerase reverse transcriptase (TERT),which functions as the primary mechanism of telomere maintenance and regulates cellular life expectancy.Underpinning increased cell proliferation,telomerase is also a key factor in facilitating cancer cell immortalization.The review focuses on aspects of hormonal regulations of telomerase,and the intraceilular pathways that converge to regulate telomerase activity with an emphasis on molecular interactions at protein and gene levels.In addition,the basic structure and function of two key telomerase enzyme components-the catalytic subunit TERT and the template RNA (TERC) are discussed briefly.

  4. Expression of Bcl-2 in cells with different telomerase activities

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Both telomerase and Bcl-2 are important genes in controlling apoptosis. The activation of telomerase and the abnormal regulation of Bcl-2 are also closely related to carcinogenesis. However, little is known about the linkage between telomerase and Bcl-2. The effect of activated telomerase on the expression of Bcl-2 has been investigated. It is demonstrated that in tumor and transformed cells with higher telomerase activity, Bcl-2 expression is significantly lower than that in telomerase negative or less telomerose activity cells. Further study showed that in the telomerase gene-transformed 2BS-fibroblasts, Bcl-2 expression is inhibited significantly while the exogenous telomerase catalytic subunit gene is re-expressed in fibroblasts. Results indicated that there might be a certain linkage between the expression of telomerase and Bcl-2, and overexpression of exogenous telomerase gene might down regulate the expression of Bcl-2.

  5. Telomerase activity as a biomarker for (pre)neoplastic cervical disease in scrapings and frozen sections from patients with abnormal cervical smear

    NARCIS (Netherlands)

    Wisman, GBA; Hollema, H; de Jong, S; ter Schegget, J; Tjong-A-Hung, SP; Ruiters, MHJ; Krans, M; de Vries, EGE; van der Zee, AGJ

    1998-01-01

    Purpose: To evaluate the diagnostic value of semiquantitative telomerase activity assessment in cervical scrapings together with human papillomavirus (HPV) typing for detection of (pre)neoplastic cervical lesions and to compare telomerase activity in cervical scrapings and frozen specimens from the

  6. Lack of telomerase RNA gene hTERC expression in alternative lengthening of telomeres cells is associated with methylation of the hTERC promoter

    NARCIS (Netherlands)

    Hoare, SF; Bryce, LA; Wisman, GBA; Burns, S; Going, JJ; van der Zee, AGJ; Keith, WN

    2001-01-01

    The immortal phenotype of most human cancers is attributable to telomerase expression. However, a number of immortal cell lines and tumors achieve telomere maintenance in the absence of telomerase via alternative mechanisms known as ALT (alternative lengthening of telomeres). Here we show that the p

  7. The reverse transcriptase component of the Tetrahymena telomerase ribonucleoprotein complex

    OpenAIRE

    Collins, Kathleen; Gandhi, Leena

    1998-01-01

    Telomerase is a eukaryotic reverse transcriptase that adds simple sequence repeats to chromosome ends by copying a template sequence within the RNA component of the enzyme. We describe here the identification of a Tetrahymena telomerase protein with reverse transcriptase motifs, p133. This subunit is associated with the previously identified Tetrahymena telomerase RNA and the telomerase proteins p80 and p95 in immunoprecipitation assays. Therefore, all four known Tetrahymena telomerase compon...

  8. SMN and coilin negatively regulate dyskerin association with telomerase RNA

    OpenAIRE

    Aaron R. Poole; Hebert, Michael D.

    2016-01-01

    Telomerase is a ribonucleoprotein comprising telomerase RNA and associated proteins. The formation of the telomerase holoenzyme takes place in the Cajal body (CB), a subnuclear domain that participates in the formation of ribonucleoproteins. CBs also contribute to the delivery of telomerase to telomeres. The protein WRAP53 is enriched within the CB and is instrumental for the targeting of telomerase RNA to CBs. Two other CB proteins, SMN and coilin, are also suspected of taking part in some a...

  9. Untersuchungen zu diagnostischen und therapeutischen Aspekten der Telomerase beim Nierenzellkarzinom

    OpenAIRE

    Sachsinger, Jana

    2010-01-01

    The enzyme telomerase is a ribonucleoprotein DNA polymerase composed of an RNA molecule, TR (Telomerase RNA) and a catalytic subunit, TERT (Telomerase Reverse Transcriptase). Renal cell cancer is known as an chemo resistant and heterogeneous tumor entity. Examinations of telomerase were undergone to investigate possible therapeutic paths against advanced renal cell cancer. Telomerase activity was measured in two different series of renal carcinoma and were detected in 63 % and 46% respec...

  10. The C-terminal domain of Tetrahymena thermophila telomerase holoenzyme protein p65 induces multiple structural changes in telomerase RNA

    OpenAIRE

    Akiyama, Benjamin M.; Loper, John; Najarro, Kevin; Stone, Michael D.

    2012-01-01

    The C-terminal domain of Tetrahymena thermophila telomerase holoenzyme protein p65 induces multiple structural changes in telomerase RNA. Telomerase holoenzyme proteins are required to fold telomerase RNA into its active conformation. In this study, the Stone laboratory employed a combination of single-molecule FRET and RNase protection mapping to demonstrate that the C-terminal domain of the Tetrahymena telomerase holoenzyme protein p65 is essential for its RNA folding activity. RNase probin...

  11. Influence of anti-keratin autoantibodies on telomerase activity of squamous cell carcinoma

    Institute of Scientific and Technical Information of China (English)

    FU Meng; ZHANG Yan-guo; LIU Yu-feng; CHEN Yan; WANG Qiu-feng; LI Wei

    2002-01-01

    Objective: To investigate the influence of anti-keratin autoantibodies (AK auto Abs) on telomerase activity of squamous cell carcinoma cultured in vitro and the mechanisms of the inhibitory effects of AK auto Abs on squamous cell carcinoma. Methods: Influence of AK auto Abs on the proliferation of Tca cells was observed by MTT colorimetry. Telomerase activity of cultured Tca cells and human keratinocytes was determined by telomeric repeat amplication protocol-ELISA (TRAP-ELISA) and polyacrylamide gel electrophoresis (PAGE). After being treated with AK auto Abs for 36 h at a concentration of 4, 8, 16 mg/L respectively, the changes of telomerase activity of Tca cells were also detected by TRAP-ELISA and PAGE.Results: MTT colorimetric determination showed that the capacity of proliferation of Tca cells correlated negatively with the concentration of AK auto Abs (r=-0. 74, P<0. 01). TRAP-ELISA and PAGE showed that telomerase activity of Tca cells increased significantly compared to that of cultured human keratinocytes(t=3. 5396, P<0. 01). AK auto Abs at a concentrations of 4, 8, 16 mg/L had significant dose-dependent inhibitory effects on telomerase activity of Tca cells (r=- 0. 8358, P<0. 01). Conclusion: AK auto Abs have a significant dose-dependent inhibitory effect on the proliferation of cultured Tca cells. AK auto Abs inhibit telomerase activity of cultured Tca cells with dose-dependent pattern. It suggests that decrease of telomerase activity may play an important role in the inhibitory effects of AK auto Aba on squamous cell carcinoma.

  12. Telomerase activity in cervical intraepithelial neoplasia

    Institute of Scientific and Technical Information of China (English)

    王淑珍; 孙建衡; 张伟; 金顺钱; 王洪平; 金玉生; 曲萍; 刘毅; 李茉

    2004-01-01

    Background It was reported that telomerase expression is closely associated with cellular immortality and cancer. This study was designed to investigate the relationship between telomerase expression and the carcinogenesis of cervical cancer, the possible use of telomerase as a marker of cervical intraepithelial neoplasia (CIN) progression or regression, and the natural history of CIN. Methods Telomeric repeat amplification protocol (TRAP) assay was used to measure telomerase activity in cervical scrapings and biopsy samples obtained from 105 cases affected with various cervical conditions, including chronic cervicitis (n=20), CIN (n=64, 16 cases of CIN Ⅰ , 20 cases of CIN Ⅱ, and 28 cases of CIN Ⅲ ), and invasive squamous cell carcinoma (n =21 ).Results In exfoliated cell samples, telomerase activity was detected in 5 of 20 (25. 0% ) cases of cervicitis, 10 of 16 (62.5%) cases of CIN Ⅰ , 11 of 20 (55.0%) cases of CIN Ⅱ, 23 of 28 (82.1%) cases of CIN Ⅲ, and 13 of 21 (61.9%) cases of carcinoma. In cervical biopsy samples, telomerase activity was detected in 6 of 20 (30. 0%) cases of cervicitis, 8 of 16 (50. 0%) cases of CIN Ⅰ , 9 of 20 (45.0%) cases of (CIN Ⅱ, 27 of 28 (96. 4%) cases of CIN Ⅲ, and 20 of 21 (95. 2%) cases of carcinoma. Telomerase activation was significantly higher in CIN samples than in cervicitis samples. Telomerase activity was detected at similar frequency in samples from cervical scrapings and cervical biopsies.Conclusion These results seem to suggest that telomerase expression may be associated with carcinogenesis of the cervix. TRAP assay of cervical scraping samples could be used to monitor and predict the development of CIN in clinical practice.

  13. trt-1 is the Caenorhabditis elegans catalytic subunit of telomerase.

    Directory of Open Access Journals (Sweden)

    2006-02-01

    Full Text Available Mutants of trt-1, the Caenorhabditis elegans telomerase reverse transcriptase, reproduce normally for several generations but eventually become sterile as a consequence of telomere erosion and end-to-end chromosome fusions. Telomere erosion and uncapping do not cause an increase in apoptosis in the germlines of trt-1 mutants. Instead, late-generation trt-1 mutants display chromosome segregation defects that are likely to be the direct cause of sterility. trt-1 functions in the same telomere replication pathway as mrt-2, a component of the Rad9/Rad1/Hus1 (9-1-1 proliferating cell nuclear antigen-like sliding clamp. Thus, the 9-1-1 complex may be required for telomerase to act at chromosome ends in C. elegans. Although telomere erosion limits replicative life span in human somatic cells, neither trt-1 nor telomere shortening affects postmitotic aging in C. elegans. These findings illustrate effects of telomere dysfunction in C. elegans mutants lacking the catalytic subunit of telomerase, trt-1.

  14. Detection of Telomerase Activity and the Expression of Telomerase Subunits in the Patients with Acute Myelogenous Leukaemia

    Institute of Scientific and Technical Information of China (English)

    李一荣; 吴健民; 王琳; 陈凤花; 胡丽华

    2004-01-01

    Summary: Telomerase activity and the expression of telomerase subunits (for example, telomerase reverse transcriptase and telomerase associated protein 1 and telomerase RNA component) of peripheral white blood cells were detected in the patients with acute myelogenous leukaemia (AML)and the correlation between telomerase activity and the expression of telomerase subunits was observed. In 94 peripheral white blood cells from 18 healthy volunteers and 76 patients with AML,including 31 AML at initial presentation, 24 at relapse and 21 at complete remission, the telomerase activity and telomerase subunits mRNA or RNA were detected by PCR-ELISA and RT-PCR respectively. The results showed that the positive rate of telomerase from patients with AML at initial presentation, at relapse and at complete remission was 74.1 %, 79.2 % and 4.8 % respectively.The positive rate of telomerase reverse transcriptase mRNA from healthy volunteers, AML at initial presentation, AML at relapse and AML at complete remission was 5.6 %, 80. 6 %, 83.3 %and 9.5 % respectively. The positive rate of telomerase associated protein 1 mRNA and telomerase RNA component in all samples were 100 %. It was suggested that the up-regulation of telomerase activity and the expression of telomerase reverse transcriptase is correlated closely with the occurrence and relapse of AML, so telomerase activity and the expression of telomerase reverse transcriptase may be used to estimate the curative effect and predict relapse of AML. Moreover, the upregulation of telomerase activity is correlated with the expression of telomerase reverse transcriptase significantly.

  15. DETECTION OF TELOMERASE ACTIVITY IN PATIENTS WITH MYCOSIS FUNGOIDES

    Institute of Scientific and Technical Information of China (English)

    应作霖; 孙建方; 刘珊

    2003-01-01

    Objectives. To detect telomerase activity in patients with mycosis fungoides (MF) and to study therole of telomerase in the tumorigenesis of MF.Methods. The technique of PCR-ELISA was employed to detect telomerase activity in 35 patientswith various stages of MF.Results. 92.3% tumor stage of MF, 78.6% plaque stage of MF and 75.0% patch stage of MF hadpositive telomerase activity. The control samples had no telomerase activity. Telomerase activity in tumorstage of MF was significantly higher than that in plaque stage, while the latter was higher than that inpatch stage. Telomerase activity was correlated with the stage of MF.Conclusion. High level of telomerase activity frequently occurred in patients with MF, suggestingthat telomerase might play an important role in the tumorigenesis of MF and is a useful marker for thediagnosis of MF possibly.

  16. Insulin-like growth factor I stimulates telomerase activity in prostate cancer cells.

    Science.gov (United States)

    Wetterau, Lawrence A; Francis, Malik J; Ma, Liqun; Cohen, Pinchas

    2003-07-01

    IGF-I has been implicated in the pathogenesis of human cancer. We sought to establish a role for IGF-I in the regulation of telomerase, an enzyme critically involved in cancer cell immortalization. Telomerase activity was assayed in LAPC-4, PC-3, and DU-145 prostate cancer cell lines treated with and without IGF-I/IGF-I analogs. Relative expression of human telomerase reverse transcriptase (hTERT) mRNA and protein was determined by quantitative RT-PCR and Western immunoblot, respectively. IGF-I stimulated baseline telomerase activity in all three cell lines, ranging from 2- to 10-fold (P IGF concentrations as low as 10 ng/ml and was maximal at 100 ng/ml. Stimulation was noted by 0.5 h, was maximal by 8 h, and persisted to 48 h. A similar 3-fold enhancement (P Long-R3 IGF-I, but not in response to [Ala(31),Leu(60)]IGF-I. Pretreatment with the Akt kinase inhibitor wortmannin abolished the stimulatory IGF effect, whereas blockade of MAPK activity did not. Lastly, IGF-I provoked a 2-fold increase in hTERT mRNA and protein expression (P IGF-I clearly stimulates telomerase activity in prostate cancer cells through a dual mode of action, including early rapid effects probably involving phosphorylation of hTERT by Akt and later up-regulation of hTERT expression. PMID:12843187

  17. Dynamic alteration of telomerase expression and its diagnostic significance in liver or peripheral blood for hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    Deng-Fu Yao; Wei Wu; Min Yao; Li-Wei Qiu; Xin-Hua Wu; Xiao-Qin Su; Li Zou; Deng-Bing Yao; Xian-Yong Meng

    2006-01-01

    AIM: To investigate the dynamic alteration of telomerase expression during development of hepatocellular carcinoma (HCC) and its diagnostic implications in liver tissues or peripheral blood mononuclear cells for HCC.METHODS: Dynamic expressions of liver telomerase during malignant transformation of hepatocytes were observed in Sprague-Dawly (SD) rats fed with 0.05% of 2-fluoenyacetamide (2-FAA). Total RNA and telomerase were extracted from rat or human liver tissues. The telomerase activities in livers and in circulating blood were detected by a telomeric repeat amplification protocol-enzyme-linked immunosorbent assay (TRAPELISA), and its diagnostic value was investigated in patients with benign or malignant liver diseases.RESULTS: The hepatoma model displayed the dynamic expression of hepatic telomerase during HCC development. The telomerase activities were consistent with liver total RNA levels (r = 0.83, P<0.01) at the stages of degeneration, precancerosis, and cancerization of hepatocytes. In HCC patients, the telomerase levels in HCC tissues were significantly higher than in their adjacent non-cancerous tissues, but liver total RNA levels were lower in the former than in the latter. Although the circulating telomerase of HCC patients was abnormally expressed among patients with chronic liver diseases,the telomerase activity was a non-specific marker for HCC diagnosis, because the incidence was 15.7% in normal control, 25% in chronic hepatitis, 45.9% in liver cirrhosis, and 85.2% in HCC, respectively when absorbance value of telomerase activity was more than 0.2. If the value was over 0.6, the incidence was 60%in HCC group and 0% in any of the others (P<0.01)except in two cases with liver cirrhosis. However, the combination of circulating telomerase with serum alphafetoprotein level could increase the positive rate and the accuracy (92.6%, 125 of 135) of HCC diagnosis.CONCLUSION: The overexpression of telomerase is associated with HCC development, and its

  18. 以端粒酶为靶标抗癌药物筛选模型建立及端粒酶抑制剂筛选%Determination of Telomerase from HeLa Cells as a Target for Screening Antitumor Agents

    Institute of Scientific and Technical Information of China (English)

    郑晓飞; 王升启; 孙志贤

    2002-01-01

    Telomerase, a ribonucleoprotein enzyme, has been found in immortalized but not in most sonatic adult human tissues, and thus emerged as a novel target for cancer chemotherapy. Recently it has been found that telomerase is a fruitful target for oncologic drug development. A new method for screening antitumor agents by using telomerase as a target has been established according to the phenomena that the enzyme activity ean be affected bv some types of antitumor agents or chemicals. The telomerase was extracted from HeLa cells. The telomeric repeat amplification protocol(TRAP) was used to measure enzyme activity. Telomerase activity can be inhibited by 4 kinds of chemical compounds.

  19. Telomerase-Associated Protein TEP1 Is Not Essential for Telomerase Activity or Telomere Length Maintenance In Vivo

    OpenAIRE

    Liu, Yie; Snow, Bryan E.; Hande, M. Prakash; Baerlocher, Gabriela; Kickhoefer, Valerie A.; Yeung, David; Wakeham, Andrew; Itie, Annick; Siderovski, David P.; Lansdorp, Peter M.; Robinson, Murray O; Harrington, Lea

    2000-01-01

    TEP1 is a mammalian telomerase-associated protein with similarity to the Tetrahymena telomerase protein p80. Like p80, TEP1 is associated with telomerase activity and the telomerase reverse transcriptase, and it specifically interacts with the telomerase RNA. To determine the role of mTep1 in telomerase function in vivo, we generated mouse embryonic stem (ES) cells and mice lacking mTep1. The mTep1-deficient (mTep1−/−) mice were viable and were bred for seven successive generations with no ob...

  20. Inhibition of Cell Growth and Telomerase Activity in Osteosarcoma Cells by DN-hTERT

    Institute of Scientific and Technical Information of China (English)

    XU Tao; RAO Yaojian; ZHU Wentao; GUO Fengjin

    2006-01-01

    In order to study the effects of dominant negative human telomerase reverse transcriptase (DN-hTERT) on cell growth and telomerase activity in osteosarcoma cell line MG63, MG63 cells were transfected with DN-hTERT-IRES2-EGFP9 (DN) or IRES2-EGF (I, blank vector) with lipofectamine 2000. The stably transfected cells were selected with G-418. Cell growth properties were examined under a fluorescence microscope. The hTERT mRNA expression was detected by reverse transcription-polymerase chain reaction (RT-PCR). Telomerase activities were measured by TRAP-ELISE. The tumorigenicity was studied with tumor xenografts by subcutaneous injection of cancer cells into nude mice. The results showed that cell growth was suppressed in MG63 cells transfected with DN-hTERT. The hTERT mRNA was increased in N-hTERT transfected-MG63 cells (MG63/DN). The telomerase activity was 2.45±0.11 in MG63/DN cells, while 3.40±0.12 in the cells transfected with blank vector (MG63/I), (P<0.05); DN-hTERT-expressing clones did not form tumors in 2 weeks, but the ratio of tumorigenesis was 30 % in nude mice bearing MG63/I (P<0.01). It was concluded that DN-hTERT could specifically inhibit the cell growth and telomerase activity in MG63 cells.

  1. hTERT反义核酸对淋巴白血病细胞端粒酶活性的抑制%Inhibition of Telomerase Activity of Lymphoblastic Leukemic Cells by hTERT Antisense

    Institute of Scientific and Technical Information of China (English)

    张洹; 李文瑜

    2004-01-01

    Objective: To investigate the effect of antisense, human telomerase reverse transcriptase (hTERT) mRNA oligodeoxynucleotide on telomerase activity of lymphoblastic leukemic cells. Methods:Telomerase activity was measured by the telomerase PCR ELISA assay kit (TRAP), hTERT protein by immunochemistry and flowcytometry, hTERT mRNA expression by reverse transcription polymerase chain reaction (RT-PCR) assay and gel-image system. Results: Incubation of lymphoblastic leukemic cells (Jurkat, Raji and CEM cell lines) with 10 μmol/L AS PS-ODN could significantly decline the mRNA and hTERT after 72 h, and the telomerase activity was significantly down-regulated or inhibited. Conclusion:The hTERT AS PS-ODN was an excellent inhibitor for telomerase activity of lymphoblastic leukemic cells.

  2. Coexistence of Alternative Lengthening of Telomeres and Telomerase in hTERT-Transfected GM847 Cells

    OpenAIRE

    Perrem, Kilian; Colgin, Lorel M.; Neumann, Axel A.; Yeager, Thomas R.; Reddel, Roger R

    2001-01-01

    It has been shown previously that some immortalized human cells maintain their telomeres in the absence of significant levels of telomerase activity by a mechanism referred to as alternative lengthening of telomeres (ALT). Cells utilizing ALT have telomeres of very heterogeneous length, ranging from very short to very long. Here we report the effect of telomerase expression in the ALT cell line GM847. Expression of exogenous hTERT in GM847 (GM847/hTERT) cells resulted in lengthening of the sh...

  3. Effects of Combined siRNA-TR and-TERT on Telomerase Activity and Growth of Bladder Transitional Cell Cancer BIU-87 Cells

    Institute of Scientific and Technical Information of China (English)

    程文; 位志峰; 高建平; 张征宇; 葛京平; 景抗震; 徐锋; 解鹏

    2010-01-01

    The effects of combined RNA interference(RNAi) of human telomerase RNA(hTR) and human telomerase reverse transcriptase(hTERT) genes on telomerase activity in a bladder cancer cell line(BIU-87 cells) were investigated by using gene chip technology in vitro with an attempt to evaluate the role of RNAi in the gene therapy of bladder transitional cell cancer(BTCC).Three TR-specific double-stranded small interfering RNAs(siRNAs) and three TERT-specific double-stranded siRNAs were designed to target different reg...

  4. Pharmaceutical regulation of telomerase and its clinical potential

    OpenAIRE

    Sprouse, Alyssa A.; Steding, Catherine E; Herbert, Brittney-Shea

    2011-01-01

    Abstract Telomeres serve the dual function of protecting chromosomes from genomic instability as well as protecting the ends of chromosomes from DNA damage machinery. The enzyme responsible for telomere maintenance is telomerase, an enzyme capable of reverse transcription. Telomerase activity is typically limited to specific cell types. However, telomerase activation in somatic cells serves as a key step toward cell immortalization and cancer. Targeting telomerase serves as a potential cancer...

  5. Telomerase Activity and the Risk of Lung Cancer

    OpenAIRE

    Jeon, Hyo-Sung; Choi, Jin Eun; Jung, Deuk Kju; Choi, Yi Young; Kang, Hyo Gyoung; Lee, Won-Kee; Yoo, Seung Soo; Lim, Jeong-Ok; PARK, JAE YONG

    2012-01-01

    Telomerase play a key role in the maintenance of telomere length and chromosome integrity. We have evaluated the association between telomerase activity and the risk of lung cancer in peripheral blood. Telomerase activity in peripheral blood mononuclear cells was measured by a PCR-designed telomeric repeat amplification protocol in 63 lung cancer patients and 190 healthy controls that were matched for age, gender, and smoking status. Telomerase activity was significantly lower in the lung can...

  6. Functionally interacting telomerase RNAs in the yeast telomerase complex

    OpenAIRE

    Prescott, John; Elizabeth H. Blackburn

    1997-01-01

    The ribonucleoprotein (RNP) enzyme telomerase from Saccharomyces cerevisiae adds telomeric DNA to chromosomal ends in short increments both in vivo and in vitro. Whether or not telomerase functions as a multimer has not been addressed previously. Here we show, first, that following polymerization, the telomerase RNP remains stably bound to its telomeric oligonucleotide reaction product. We then exploit this finding and a previously reported mutant telomerase RNA to demonstrate that, unexpecte...

  7. Collapse of Telomere Homeostasis in Hematopoietic Cells Caused by Heterozygous Mutations in Telomerase Genes

    NARCIS (Netherlands)

    Aubert, Geraldine; Baerlocher, Gabriela M.; Vulto, Irma; Poon, Steven S.; Lansdorp, Peter M.

    2012-01-01

    Telomerase activity is readily detectable in extracts from human hematopoietic stem and progenitor cells, but appears unable to maintain telomere length with proliferation in vitro and with age in vivo. We performed a detailed study of the telomere length by flow FISH analysis in leukocytes from 835

  8. The Roles of Telomerase in the Generation of Polyploidy during Neoplastic Cell Growth

    Directory of Open Access Journals (Sweden)

    Agni Christodoulidou

    2013-02-01

    Full Text Available Polyploidy contributes to extensive intratumor genomic heterogeneity that characterizes advanced malignancies and is thought to limit the efficiency of current cancer therapies. It has been shown that telomere deprotection in p53-deficient mouse embryonic fibroblasts leads to high rates of polyploidization. We now show that tumor genome evolution through whole-genome duplication occurs in ∼15% of the karyotyped human neoplasms and correlates with disease progression. In a panel of human cancer and transformed cell lines representing the two known types of genomic instability (chromosomal and microsatellite, as well as the two known pathways of telomere maintenance in cancer (telomerase activity and alternative lengthening of telomeres, telomere dysfunction-driven polyploidization occurred independently of the mutational status of p53. Depending on the preexisting context of telomere maintenance, telomerase activity and its major components, human telomerase reverse transcriptase (hTERT and human telomerase RNA component (hTERC, exert both reverse transcriptase-related (canonical and noncanonical functions to affect tumor genome evolution through suppression or induction of polyploidization. These new findings provide a more complete mechanistic understanding of cancer progression that may, in the future, lead to novel therapeutic interventions.

  9. HPV detection and measurement of HPV-16, telomerase, and survivin transcripts in colposcopy clinic patients

    OpenAIRE

    Lanham, S; Herbert, A.; Watt, P

    2001-01-01

    Aims—To determine whether the detection of high risk human papillomavirus (HPV) types is more predictive for high grade CIN than the current cervical smear test, and whether the production and measurement of HPV type 16 (HPV-16) and cellular survivin and telomerase transcripts can be used to discriminate between cervical HPV infections that self cure and those that induce high grade lesions.

  10. EFFECTS OF ARSENITE IN TELOMERE AND TELOMERASE IN RELATION TO CELL PROLIFERATION AND APOPTOSIS IN HUMAN KERATINOCYTES AND LEUKEMIA CELLS IN VITRO

    Science.gov (United States)

    Telomeres are critical in maintaining chromosome and genomic stability. Arsenic, a human carcinogen as well as an anticancer agent, is known for its clastogenicity. To better understand molecular mechanisms of arsenic actions, we investigated arsenite effects on telomere and telo...

  11. Effect of realgar on telomerase activity and hTERT-mRNA expression in NB4 cells

    Institute of Scientific and Technical Information of China (English)

    李静; 刘陕西; 张梅

    2003-01-01

    Objective: To evaluate whether realgar could down-regulate human telomerase reverse transcriptase (hTERT) gene expression and telomerase activity in acute promyelocytic leukemia cell line-NB4 cells. Methods: The expression of hTERT-mRNA was analyzed by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR). Telomerase activity was determined by polymerase chain reaction enzyme-linked immunoassay (PCR-ELISA). Flow cytometry using PI staining was applied to analyze the cell cycle and apoptosis. Results: Treatment of NB4 cells with 155, 300, 600 μg/L realgar reduced telomerase activity significantly accompanying with decrease of hTERT-mRNA and increasing cell apoptosis. G2/M phase arrest appeared when treated with realgar in 300, 600 μg/L. Conclusion: It is suggested that telomerase activity of NB4 cells can be specifically inhibited by realgar through the down-regulation of hTERT gene expression. G2/M phase arrest and apoptosis by realgar in NB4 cells might be related to the reduction of telomerase activity and hTERT-mRNA expression.

  12. Are the DMs the result of gene amplification of the telomerase components after irradiation?

    International Nuclear Information System (INIS)

    Full text: The main objective is to test the hypothesis that considers the DM (double minutes) as the cytological sign of telomerase gene amplification after irradiation, on human, in vivo and in vitro. Irradiations were performed at Electron Accelerators Laboratory, National Institute for Laser, Plasma and Radiation Physics, Magurele-Bucharest, Romania. The samples were irradiated using an ALIN 10 linear electron accelerator. The peripheral blood for in vitro studies was collected from an aged 25, healthy, non-smoker donor and for in vivo studies from five subjects who are working in a potentially mutagenic environment. The doses used to irradiate in vitro human blood were: 4, 6, 8, 10 Gy. For FISH the probes were: one probe for revealing the telomeres and the second one for the RNA telomerase compound. For the molecular analyses, we used the TRAPeze Telomerase detection kit. The most informative dose for the appearance of DM (frequency 26%) was at 8 Gy, so we have chosen this dose in order to perform further experiments. In vivo tests did not revealed any DMs. Because of that, in our further studies, no more experimental work was done on this samples. After the in vitro irradiation, in cases of chromosomal interchanges or translocations, we did not identify the telomeric fluorescent signal at the chromosomal ends. This observation and the fact that we found the signal on different acentric fragments revealed that the radiation generates important destruction at the level of chromosomal ends. From the FISH analysis, we detect the RNA telomerase component on chromosome 3 q, at the two homologous chromosomes in normal probes and also in irradiated one. The fact that we did not found additional signals after irradiation revealed that the telomerase is not amplified in order to repair the broken telomeres. We have tried to detect changes in expression of the telomerase enzyme normal/irradiated sample by the TRAPeze detection kit, all the samples analyzed revealing the

  13. Genomic amplification patterns of human telomerase RNA gene and C-MYC in liquid-based cytological specimens used for the detection of high-grade cervical intraepithelial neoplasia

    Directory of Open Access Journals (Sweden)

    Chen Shaomin

    2012-04-01

    Full Text Available Abstract Background The amplification of oncogenes initiated by high-risk human papillomavirus (HPV infection is an early event in cervical carcinogenesis and can be used for cervical lesion diagnosis. We measured the genomic amplification rates and the patterns of human telomerase RNA gene (TERC and C-MYC in the liquid-based cytological specimens to evaluate the diagnostic characteristics for the detection of high-grade cervical lesions. Methods Two hundred and forty-three residual cytological specimens were obtained from outpatients aged 25 to 64 years at Qilu Hospital, Shandong University. The specimens were evaluated by fluorescence in situ hybridization (FISH using chromosome probes to TERC (3q26 and C-MYC (8q24. All of the patients underwent colposcopic examination and histological evaluation. A Chi-square test was used for categorical data analysis. Results In the normal, cervical intraepithelial neoplasia grade 1 (CIN1, grade 2 (CIN2, grade 3 (CIN3 and squamous cervical cancer (SCC cases, the TERC positive rates were 9.2%, 17.2%, 76.2%, 100.0% and 100.0%, respectively; the C-MYC positive rates were 20.7%, 31.0%, 71.4%, 81.8% and 100.0%, respectively. The TERC and C-MYC positive rates were higher in the CIN2+ (CIN2, CIN3 and SCC cases than in the normal and CIN1 cases (p p p > 0.05. Conclusions The TERC test is highly sensitive and is therefore suitable for cervical cancer screening. The C-MYC test is not suitable for cancer screening because of its lower sensitivity. The amplification patterns of TERC become more diverse and complex as the severity of cervical diseases increases, whereas for C-MYC, the amplification patterns are similar between the normal/CIN1 and CIN2+ groups. Virtual slides The virtual slide(s for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1308004512669913.

  14. Effects of phosphorothioate anti-sense oligodeoxynucleotides on colorectal cancer cell growth and telomerase activity

    Institute of Scientific and Technical Information of China (English)

    Xi-Shan Wang; Kuan Wang; Xue Li; Song-Bin Fu

    2004-01-01

    AIM: To investigate the inhibitory effect of phosphorothioate anti-sense oligodeoxynucleotides (PASODN) on colorectal cancer LS-174T cells in vitro and the mechanism of inhibition of telomerase activity in these cells.METHODS: PASODN were used to infect LS-174T cells and block human telomerase RNA (hTR) through anti-sense technology. The inhibitory effect of PASODN was evaluated by colony-forming inhibition assay and growth curve. Changes of telomerase activity in LS-174T cells were detected by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA), and the level of apoptosis was analyzed by flow cytometry (FCM) assay.RESULTS: PASODN showed a dose and time-dependent inhibition of cell proliferation. The optimal dosage of PASODN was 10 μmol/L. The colony-forming efficiency was 10.3% in PASODN group after 10 d, whereas that in phosphorothioate mis-sense oligodeoxynucleotides (PMSODN) group with the same concentration and in PBS group (blank control) was 49.1% and 50.7%, respectively. PCR-ELISA results indicated that telomerase activity in the PASODN group was obviously inhibited in comparison with in the control groups (P<0.01,t = 3.317 and 3.241, t0.01 (20) = 2.845). Meanwhile, before the number of cells was decreased, the morphological changes were observed in the cells of PASODN group. The cells in PASODN group showed the apoptotic peak at 72 h after infection, whereas the control group did not show.CONCLUSION: Specific sequence oligonucleotides can inhibit telomerase activity and lead to cell apoptosis,suggesting a novel treatment strategy for malignant tumors induced by telomerase.

  15. The Telomerase/Vault-Associated Protein Tep1 Is Required for Vault RNA Stability and Its Association with the Vault Particle

    OpenAIRE

    Kickhoefer, Valerie A; Liu, Yie; Kong, Lawrence B.; Snow, Bryan E.; Stewart, Phoebe L.; Harrington, Lea; Rome, Leonard H.

    2001-01-01

    Vaults and telomerase are ribonucleoprotein (RNP) particles that share a common protein subunit, TEP1. Although its role in either complex has not yet been defined, TEP1 has been shown to interact with the mouse telomerase RNA and with several of the human vault RNAs in a yeast three-hybrid assay. An mTep1 −/− mouse was previously generated which resulted in no apparent change in telomere length or telomerase activity in six generations of mTep1-deficient mice. Here we show that the levels of...

  16. Evolutionary perspectives of telomerase RNA structure and function.

    Science.gov (United States)

    Podlevsky, Joshua D; Chen, Julian J-L

    2016-08-01

    Telomerase is the eukaryotic solution to the 'end-replication problem' of linear chromosomes by synthesising the highly repetitive DNA constituent of telomeres, the nucleoprotein cap that protects chromosome termini. Functioning as a ribonucleoprotein (RNP) enzyme, telomerase is minimally composed of the highly conserved catalytic telomerase reverse transcriptase (TERT) and essential telomerase RNA (TR) component. Beyond merely providing the template for telomeric DNA synthesis, TR is an innate telomerase component and directly facilitates enzymatic function. TR accomplishes this by having evolved structural elements for stable assembly with the TERT protein and the regulation of the telomerase catalytic cycle. Despite its prominence and prevalence, TR has profoundly diverged in length, sequence, and biogenesis pathway among distinct evolutionary lineages. This diversity has generated numerous structural and mechanistic solutions for ensuring proper RNP formation and high fidelity telomeric DNA synthesis. Telomerase provides unique insights into RNA and protein coevolution within RNP enzymes. PMID:27359343

  17. Relationship between microvessel density and telomerase activity in hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    Yun-Feng Piao; Min He; Yang Shi; Tong-Yu Tang

    2004-01-01

    AIM: To study the relationship between microvessel density (MVD), telomerase activity and biological characteristics in hepatocellular carcinoma (HCC).METHODS: S-P immunohistochemical method and telomeric repeat amplification protocol (TRAP) were respectively used to analyze the MVD and telomerase activity in 58 HCC and adjacent normal tissues.RESULTS: The MVD in HCC with metastasis, lower differentiation or without intact capsule was significantly higher than that in HCC with intact capsule, higher differentiation, or without metastasis. While MVD had no relationship with tumor size, hepatic virus infection and other clinical factors. Telomerase activity was related to differentiation degree, but not to tumor size or histological grade. MVD in HCC with telomerase activity was higher than that in HCC without telomerase activity.CONCLUSION: MVD and telomerase activity may serve as diagnostic criteria of HCC in earlier stage. Meanwhile,there may be a cooperative effect between MVD and telomerase on the growth and metastasis of HCC.

  18. Telomeres and Telomerase in the Radiation Response: implications for instability, reprogramming, and carcinogenesis

    Directory of Open Access Journals (Sweden)

    Brock James Sishc

    2015-11-01

    Full Text Available Telomeres are nucleoprotein complexes comprised of tandem arrays of repetitive DNA sequence that serve to protect chromosomal termini from inappropriate degradation, as well as to prevent these natural DNA ends from being recognized as broken DNA (double-strand breaks; DSBs and triggering of inappropriate DNA damage responses. Preservation of telomere length requires telomerase, the specialized reverse transcriptase capable of maintaining telomere length via template-mediated addition of telomeric repeats onto the ends of newly synthesized chromosomes. Loss of either end-capping function or telomere length maintenance has been associated with genomic instability or senescence in a variety of settings; therefore telomeres and telomerase have well-established connections to cancer and aging. It has long been recognized that oxidative stress promotes shortening of telomeres, and that telomerase activity is a radiation-inducible function. However, the effects of ionizing radiation (IR exposure on telomeres per se are much less well understood and appreciated. To gain a deeper understanding of the roles telomeres and telomerase play in the response of human cells to ionizing radiations of different qualities, we tracked changes in telomeric end-capping function, telomere length, and telomerase activity in panels of mammary epithelial and hematopoietic cell lines exposed to low linear energy transfer (LET gamma(γ-rays or high LET high charge, high energy (HZE particles, delivered either acutely or at low dose rates (LDR. In addition to demonstrating that dysfunctional telomeres contribute to IR-induced mutation frequencies and genome instability, we reveal non-canonical roles for telomerase, in that telomerase activity was required for IR-induced enrichment of mammary epithelial putative stem/progenitor cell populations, a finding also suggestive of cellular reprogramming. Taken together, the results reported here establish the critical importance of

  19. Conditionally replicative adenovirus under the control of glial fibrillary acidic protein and human telomerase reverse transcriptase dual-promoters direct sodium iodide symporter expression for malignant glioma radioiodine therapy

    International Nuclear Information System (INIS)

    Objective: To explore the possibility of using 131I as a targeted therapy method for malignant glioma by infecting U87 and U251 cells with conditionally replicative adenovirus Ad-Tp-E1a-Gp-NIS. Methods: Human telomerase reverse transcriptase (hTERT) promoter and glial fibrillary acidic protein (GFAP) promoter were cloned and their transcriptional activities were detected by luciferase assay. The conditionally replicative adenovirus Ad-Tp-E1 a-Gp-NIS was constructed,purified,and transfected into U87 and U251 glioma cells. For these transfected cells, the selective replication ability was evaluated by plaque forming assay, and protein expression was detected by Western blot assay. 125I-iodide uptake and exflux, the clone formation of 131I-iodide treated cells were also measured. Results: Transcriptions activity of the GFAP and hTERT promoters was 59.75%-62.10% (F = 11.89, P < 0.01) in U87 cells and 37.31%-49.00% (F = 5.87, P < 0.05) in U251 cells. The Ad-Tp-E1a-Gp-NIS could be selectively replicated and the hNIS gene was successfully expressed in the hTERT-positive and GFAP-positive glioma cells which showed two protein bands with relative molecular mass of 120 × 103 and 49 × 103 in Western blot assay. After infection with Ad-Tp-E1a-Gp-NIS, the cell ability of 125I uptake was increased by 78.80 (F = 2 914.58, P <0.01) and 92.48 (F = 2 275.91, P <0.01) times in U87 and U251 cells, respectively. The GFAP-negative MRC-5 cells could not take in 125I. The in vitro clonogenic assay indicated that, after 131I treatment, more than 90% of the transfected cells were killed, while only about 65% (t = 11.73-78.33, P < 0.01) of control cells were killed. Conclusions: The Ad-Tp-E1a-Gp-NIS has a good ability in selective replication and the enhancement of antitumor therapy effect by increasing tumor-specific iodide uptake in malignant glioma cells. (authors)

  20. Activin inhibits telomerase activity in cancer

    Energy Technology Data Exchange (ETDEWEB)

    Katik, Indzi; Mackenzie-Kludas, Charley; Nicholls, Craig [Department of Immunology, Monash University, Melbourne (Australia); Jiang, Fang-Xu [Centre for Diabetes Research, Western Australian Institute for Medical Research and The University of Western Australia, Perth (Australia); Zhou, Shufeng [School of Health Sciences, RMIT University, Melbourne (Australia); Li, He [Department of Immunology, Monash University, Melbourne (Australia); Liu, Jun-Ping, E-mail: jun-ping.liu@med.monash.edu.au [Department of Immunology, Monash University, Melbourne (Australia)

    2009-11-27

    Activin is a pleiotropic cytokine with broad tissue distributions. Recent studies demonstrate that activin-A inhibits cancer cell proliferation with unknown mechanisms. In this report, we demonstrate that recombinant activin-A induces telomerase inhibition in cancer cells. In breast and cervical cancer cells, activin-A resulted in telomerase activity in a concentration-dependent manner. Significant inhibition was observed at 10 ng/ml of activin-A, with a near complete inhibition at 80 ng/ml. Consistently, activin-A induced repression of the telomerase reverse transcriptase (hTERT) gene, with the hTERT gene to be suppressed by 60-80% within 24 h. In addition, activin-A induced a concomitant increase in Smad3 signaling and decrease of the hTERT gene promoter activity in a concentration-dependent fashion. These data suggest that activin-A triggered telomerase inhibition by down-regulating hTERT gene expression is involved in activin-A-induced inhibition of cancer cell proliferation.

  1. ARSENIC EFFECTS ON TELOMERE AND TELOMERASE ACTIVITY

    Science.gov (United States)

    Arsenic effects on telomere and telomerase activity. T-C. Zhang, M. T. Schmitt, J. Mo, J. L. Mumford, National Research Council and U.S Environmental Protection Agency, NHEERL, Research Triangle Park, NC 27711Arsenic is a known carcinogen and also an anticancer agent for acut...

  2. Relationship between telomerase activity and its subunit expression and inhibitory effect of antisense hTR on pancreatic carcinoma

    Institute of Scientific and Technical Information of China (English)

    Jia-Hua Zhou; Hong-Mei Zhang; Quan Chen; Dong-Dong Han; Fei Pei; Li-Shan Zhang; De-Tong Yang

    2003-01-01

    AIM: To directly investigate the relationship between telomerase activity and its subunit expression and the inhibitory effect of antisense hTR on pancreatic carcinogenesis.METHODS: We examined the telomerase activity and its subunit expression by cell culture, polymerase chain reaction (PCR), PCR-silver staining, PCR-ELISA, DNA sequencing, MTT and flow cytometry methods.RESULTS: PCR-silver staining and PCR-ELISA methods had the same specificity and sensitivity as the TRAP method.Telomerase activity was detected in the extract of the 10th,20th and 30th passages of P3 cells,while it was absent in fibroblasts. Furthermore, after the 30th generation, the proliferation period of fibroblast cells was significantly prolonged. Telomerase activity and hTERTmRNA were detected in two pancreatic carcinoma cell lines, but were found to be negative in human fibroblast cells. Telomerase activity and hTERTmRNA were tested in pancreatic carcinoma specimens of 24 cases. The telomerase activity was positive in 21 of the 24 cases (87.5 %), and the hTERTmRNA in 20 cases (83.3 %). In adjacent normal tissues positive rates were both 12.5 %. There was a significant difference between the two groups. This indicated a significant correlation between the expression level of telomerase activity and histologic differentiation,metastasis and advanced clinical stage of pancreatic carcinoma. Our findings showed that the expressions of hTR and TP1mRNA were not correlated with the activity of telomerase but the expression of hTERTmRNA was. After treatment with PS-ODNs, telomerase activity in P3 cells weakened and the inhibiting effect became stronger with an increase in PS-ODNs concentration. There was a significant difference between different PS-ODN groups (P<0.05). Inhibition of telomerase activity occurred most significant with PS-ODN1.The results of the FCM test of pancreatic cancer P3 cells showed an increase in the apoptotic rate with increasing PS-ODN1 and PS-ODN2concentrations

  3. Effects on Telomerase Activity and Associated-Protein of hRPE Cells by TGF-β1

    Institute of Scientific and Technical Information of China (English)

    Hong Zhao; Shuiqing Zeng; Xiaohong Zhu; Zhigao Zuo; Qingguang Zeng; Weijing Chao

    2003-01-01

    Purpose: To investigate the effects on telomerase activity, human telomerase reversetranscriptase (hTERT) gene and TEP1 mRNA of retinal pigment epithelial (RPE) cells weretreated by TGF-β1 of different concentration.Methods: The cultured human RPE cells were treated with TGF-β1 at differentconcentration(0 ng/ml, 0. 01 ng/ml, 0.1 ng/ml, 1 ng/ml, 10 ng/ml) for 24 h, thentelomerase activity was detected by telomerase repeat amplification protocol(TRAP). Theexpression of hTERT mRNA and TEP-1mRNA were detected by reverse transcriptionpolymerase chain reaction(RT-PCR).Results: TRAP and RT-PCR showed when the concentration of TGF-β1 was graduallyincreased, telomerase activity and the expression of hTERTmRNA were gradually reduced,TEP1mRNA showed no apparent differential expression.Conclusion: TGF-β1 can down-regulate telomerase activity and the expression of hTERTmRNA, but no effection on TEP-1mRNA, hTERTmRNA expression was in accordance withtelomerase activity in hRPE cells, hTERT gene plays a crucial role in the expression oftelomerase activity, while TEP1 plays a much smaller role.

  4. Telomere Elongation and Naive Pluripotent Stem Cells Achieved from Telomerase Haplo-Insufficient Cells by Somatic Cell Nuclear Transfer

    Directory of Open Access Journals (Sweden)

    Li-Ying Sung

    2014-12-01

    Full Text Available Haplo-insufficiency of telomerase genes in humans leads to telomere syndromes such as dyskeratosis congenital and idiopathic pulmonary fibrosis. Generation of pluripotent stem cells from telomerase haplo-insufficient donor cells would provide unique opportunities toward the realization of patient-specific stem cell therapies. Recently, pluripotent human embryonic stem cells (ntESCs have been efficiently achieved by somatic cell nuclear transfer (SCNT. We tested the hypothesis that SCNT could effectively elongate shortening telomeres of telomerase haplo-insufficient cells in the ntESCs with relevant mouse models. Indeed, telomeres of telomerase haplo-insufficient (Terc+/− mouse cells are elongated in ntESCs. Moreover, ntESCs derived from Terc+/− cells exhibit naive pluripotency as evidenced by generation of Terc+/− ntESC clone pups by tetraploid embryo complementation, the most stringent test of naive pluripotency. These data suggest that SCNT could offer a powerful tool to reprogram telomeres and to discover the factors for robust restoration of telomeres and pluripotency of telomerase haplo-insufficient somatic cells.

  5. Simulated microgravity alters multipotential differentiation of rat mesenchymal stem cells in association with reduced telomerase activity

    Science.gov (United States)

    Sun, Lianwen; Gan, Bo; Fan, Yubo; Xie, Tian; Hu, Qinghua; Zhuang, Fengyuan

    Microgravity is one of the most important characteristics in space flight. Exposure to microgravity results in extensive physiological changes in humans. Bone loss is one of the changes with serious consequences; however, the mechanism retains unclear. As the origin of osteoprogenitors, mesenchymal stem cells (MSCs) may play an important role in it. After cultured under simulated microgravity (in a rotary cell culture system, RCCS), MSCs were stained using oil red O to identify adipocytes. The mRNA level of bone morphogenetic protein (BMP)-2 and peroxisome proliferators-activated receptor (PPAR) γ2 was determined by RT-PCR. Otherwise, MSCs were induced to osteogenic differentiation after microgravity culture, and then the activity of alkaline phosphatase (ALP) was determined by PNPP and the content of osteocalcin (OC) by ELISA. Furthermore, the telomerase activity in MSCs was measured by TRAP. The results showed that simulated microgravity inhibited osteoblastic differentiation and induced adipogenic differentiation accompanied by the change of gene expression of BMP-2 and PPARγ2 in MSCs. Meanwhile, the telomerase activity decreased significantly in MSCs under simulated microgravity. The reduced bone formation in space flight may partly be due to the altered potential differentiation of MSCs associated with telomerase activity which plays a key role in regulating the lifespan of cell proliferation and differentiation. Therefore, telomerase activation/replacement may act as a potential countermeasure for microgravity-induced bone loss.

  6. A Highly Sensitive Telomerase Activity Assay that Eliminates False-Negative Results Caused by PCR Inhibitors

    Directory of Open Access Journals (Sweden)

    Hidenobu Yaku

    2013-09-01

    Full Text Available An assay for telomerase activity based on asymmetric polymerase chain reaction (A-PCR on magnetic beads (MBs and subsequent application of cycling probe technology (CPT is described. In this assay, the telomerase reaction products are immobilized on MBs, which are then washed to remove PCR inhibitors that are commonly found in clinical samples. The guanine-rich sequences (5'-(TTAGGGn-3' of the telomerase reaction products are then preferentially amplified by A-PCR, and the amplified products are subsequently detected via CPT, where a probe RNA with a fluorophore at the 5' end and a quencher at the 3' end is hydrolyzed by RNase H in the presence of the target DNA. The catalyst-mediated cleavage of the probe RNA enhances fluorescence from the 5' end of the probe. The assay allowed us to successfully detect HeLa cells selectively over normal human dermal fibroblast (NHDF cells. Importantly, this selectivity produced identical results with regard to detection of HeLa cells in the absence and presence of excess NHDF cells; therefore, this assay can be used for practical clinical applications. The lower limit of detection for HeLa cells was 50 cells, which is lower than that achieved with a conventional telomeric repeat amplification protocol assay. Our assay also eliminated false-negative results caused by PCR inhibitors. Furthermore, we show that this assay is appropriate for screening among G-quadruplex ligands to find those that inhibit telomerase activity.

  7. Essential role for telomerase in chronic myeloid leukemia induced by BCR-ABL in mice

    OpenAIRE

    Vicente-Dueñas, Carolina; Barajas-Diego, Marcos; Romero-Camarero, Isabel; González-Herrero, Inés; Flores, Teresa; Sánchez García, Isidro

    2012-01-01

    The telomerase protein is constitutively activated in malignant cells from many patients with cancer, including the chronic myeloid leukemia (CML), but whether telomerase is essential for the pathogenesis of this disease is not known. Here, we used telomerase deficient mice to determine the requirement for telomerase in CML induced by BCR-ABL in mouse models of CML. Loss of one telomerase allele or complete deletion of telomerase prevented the development of leukemia induced by BCR-ABL. Howev...

  8. The Clinical Study of Telomerase Activity in Gastric Tumor

    Institute of Scientific and Technical Information of China (English)

    XI Weihong; NI Xiaoqian; SHEN Yuqin; HUANG Qinmei

    2002-01-01

    Telomerase activity was detected with both telomeric repeat amplification protocol (TRAP) - silver stain and polymerase chain reaction (PCR) - enzyme linked immuno - sorbent assay (ELISA). We have studied the telomerase activity in the 68 gastric tumors and their neighboring tissues,25 gastric ulcer, and 3 tumor cell colonies. The positive rate of telomerase activity in gastric tumors was 86.8% (59/68) and which was obviously higher than 7.3% (5/68) in the normal tissues adjacent to the tumors and 4% (1/25) in gastric ulcer. The telomerase activity was 100% (3/3) in the tumor colonies. It allowed to be seen that higher telomerase activity was associated with the origin and development of the gastric tumor. We believe that telomerase activity may be a useful clinical diagnostic marker for the gastric tumor.

  9. [Telomere length and telomerase activity in hepatocellular carcinoma].

    Science.gov (United States)

    Nakashio, R; Kitamoto, M; Nakanishi, T; Takaishi, H; Takahashi, S; Kajiyama, G

    1998-05-01

    Telomerase activity and terminal restriction fragment (TRF) length were examined in hepatocellular carcinoma (HCC). Telomerase activity was assayed by telomeric repeat amplification protocol (TRAP) connected with an internal telomerase assay standard (ITAS). The incidence of strong telomerase activity (highly variable level compared with the activity of non-cancerous liver tissue) was 79% in well, 84% in moderately, and 100% in poorly differentiated HCC, while 0% in non-cancerous liver tissues. The incidence of TRF length alteration (reduction or elongation) was 53% in HCC. The incidence of TRF alteration was significantly higher in HCC exceeding 3 cm in diameter, moderately or poorly differentiated in histology. Telomerase activity was not associated with TRF length alteration in HCC. In conclusion, strong telomerase activity and TRF length alteration increased with HCC tumor progressions. PMID:9613130

  10. 放射性皮肤溃疡中端粒酶逆转录晦表达与癌变及难愈合的机制%Differential expression of telomerase reverse transcriptase in chronic human skin ulcer induced by radiation and mechanism of cancer transformation and poor healing

    Institute of Scientific and Technical Information of China (English)

    赵坡; 刘武; 李志军; 吕亚莉; 钟梅; 谷庆阳; 王德文

    2003-01-01

    AIM: To study the expression of the catalytic subunit of telomerase, telomerase revere transcriptase(TRT) and explore the possible relationship between the TRT and cancer txanaformation or poor healing in radiation-induced chronic human skin ulcer. METHODS: Rabbit antibody to human TRT and SP immunohistochemical method were used to detect TRT expression in 24 cases of formalin-fixed, paraffin-embeded chronic human skin ulcer tissues induced by radiation, 5 cases of normal skin, 2 of burnt skin, and 8 of carcinoma. RESULTS: The TRT was detected positive in 14 of 24 (58.3%) chronic radiation ulcers, of which the stxongly positive was 10 of 24 (41.7%) and the weakly positive 4 of 24 (16. 7% ); in 0 of 5 normal and 0 of 2 burnt skins; and in 8 of 8 (100%) carcinomas. The expression of TRT was observed almost always strongly positive in the cytoplasm and nucleus of squamous epithelial cells of epidermis but negatively in the endoepithelial cells of capillaries and small blood vessels, or weakly in the cytoplasm of smooth myocytes of media and fibroblssts, of dermis. Chronic inflammtory cells, such an plasma cells and lymphocytes also showed weakly positive for TRT. CONCLUSION: The strong TRT expression in the epidermis could be involved in the cancer transformation from chronic radiation ulcer to scuamous carcinoma, whereas the negative or weak TRT expression in the capillaries, small blood vessels and fibroblasts of dermis might be responsible for the poor healing of chronic ulcers induced by radiation, caused by sclerosis of small blood vessels and lack of granulation tissue consisting of capillaries and fibroblasts.

  11. Effects of All-trans Retinoic Acid on hTERT Gene Expression and Telomerase Activity of HL-60 Cells

    Institute of Scientific and Technical Information of China (English)

    HEDongmei; ZHANGYuan

    2003-01-01

    Objective: To investigate the effects of all-trans retinoic acid (ATRA) on human telomerase reverse transcriptase (hTERT) protein expression and telomerase activity in HL-60 cells. Methods: The expression of hTERT protein was assayed by immunofluorescence using fluoresce isothiocyanate label and telomerase activity was determined by polymerase chain reaction enzyme-linked immunoassay with HL-60 cells untreated or treated with ATRA. Cell cycle was analyzed by flow cytometry. Results: After treatment with 1μmol/L ATRA for 24, 48, 72 h, mean fluorescence intensity of hTERT protein in HL-60 cells was 61.87±4.36, 37.47±2.85, 33.45±2.37,respectively. There was a significant decrease in hTERT protein expression compared to the cells untreated, and the effect had statistically significant difference (P<0.05).Telomerase activity was decreased significantly in HL-60 cells treated with 1μmol/L ATRA for 48, 72h as compared to the cells untreated (P<0.05). Conclusion: ATRA could inhibit telomerase activity and hTERT gene expression in HL-60 cells.

  12. Disruption of the telomerase catalytic subunit gene from Arabidopsis inactivates telomerase and leads to a slow loss of telomeric DNA

    OpenAIRE

    Fitzgerald, Matthew S.; Riha, Karel; Gao, Feng; Ren, Shuxin; McKnight, Thomas D.; Shippen, Dorothy E.

    1999-01-01

    Telomerase is an essential enzyme that maintains telomeres on eukaryotic chromosomes. In mammals, telomerase is required for the lifelong proliferative capacity of normal regenerative and reproductive tissues and for sustained growth in a dedifferentiated state. Although the importance of telomeres was first elucidated in plants 60 years ago, little is known about the role of telomeres and telomerase in plant growth and development. Here we report the cloning and characterization of the Arabi...

  13. Critical telomerase activity for uncontrolled cell growth.

    Science.gov (United States)

    Wesch, Neil L; Burlock, Laura J; Gooding, Robert J

    2016-01-01

    The lengths of the telomere regions of chromosomes in a population of cells are modelled using a chemical master equation formalism, from which the evolution of the average number of cells of each telomere length is extracted. In particular, the role of the telomere-elongating enzyme telomerase on these dynamics is investigated. We show that for biologically relevant rates of cell birth and death, one finds a critical rate, R crit, of telomerase activity such that the total number of cells diverges. Further, R crit is similar in magnitude to the rates of mitosis and cell death. The possible relationship of this result to replicative immortality and its associated hallmark of cancer is discussed. PMID:27500377

  14. Critical telomerase activity for uncontrolled cell growth

    Science.gov (United States)

    Wesch, Neil L.; Burlock, Laura J.; Gooding, Robert J.

    2016-08-01

    The lengths of the telomere regions of chromosomes in a population of cells are modelled using a chemical master equation formalism, from which the evolution of the average number of cells of each telomere length is extracted. In particular, the role of the telomere-elongating enzyme telomerase on these dynamics is investigated. We show that for biologically relevant rates of cell birth and death, one finds a critical rate, R crit, of telomerase activity such that the total number of cells diverges. Further, R crit is similar in magnitude to the rates of mitosis and cell death. The possible relationship of this result to replicative immortality and its associated hallmark of cancer is discussed.

  15. Telomerase Reverse Transcriptase (TERT) is a Therapeutic Target of Oleanane Triterpenoid CDDO-Me in Prostate Cancer

    OpenAIRE

    GAUTAM, SUBHASH C.; Dorrah Deeb; Ali S. Arbab; Xiaohua Gao; Yongbo Liu

    2012-01-01

    Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is an synthetic oleanane triterpenoid with strong antiprolifertive and proapoptotic activities in cancer cells. However, the effect of CDDO-Me on human telomerase reverse transcriptase (hTERT) and its telomerase activity in prostate cancer cells has not been studied. We investigated the role of hTERT in mediating the anticancer activity of CDDO-Me in prostate cancer cells in vitro and in vivo. The inhibition of cell proliferation ...

  16. Formation of radiation induced chromosome aberrations: involvement of telomeric sequences and telomerase

    International Nuclear Information System (INIS)

    As telomeres are crucial for chromosome integrity; we investigated the role played by telomeric sequences in the formation and in the transmission of radio-induced chromosome rearrangements in human cells. Starting from interstitial telomeric sequences (ITS) as putative region of breakage, we showed that the radiation sensitivity is not equally distributed along chromosomes and. is not affected by ITS. On the contrary, plasmid integration sites are prone to radio-induced breaks, suggesting a possible integration at sites already characterized by fragility. However plasmids do not preferentially insert at radio-induced breaks in human cells immortalized by telomerase. These cells showed remarkable karyotype stability even after irradiation, suggesting a role of telomerase in the genome maintenance despite functional telomeres. Finally, we showed that the presence of more breaks in a cell favors the repair, leading to an increase of transmissible rearrangements. (author)

  17. Formation of radiation induced chromosome aberrations: involvement of telomeric sequences and telomerase

    Energy Technology Data Exchange (ETDEWEB)

    Pirzio, L.

    2004-07-15

    As telomeres are crucial for chromosome integrity; we investigated the role played by telomeric sequences in the formation and in the transmission of radio-induced chromosome rearrangements in human cells. Starting from interstitial telomeric sequences (ITS) as putative region of breakage, we showed that the radiation sensitivity is not equally distributed along chromosomes and. is not affected by ITS. On the contrary, plasmid integration sites are prone to radio-induced breaks, suggesting a possible integration at sites already characterized by fragility. However plasmids do not preferentially insert at radio-induced breaks in human cells immortalized by telomerase. These cells showed remarkable karyotype stability even after irradiation, suggesting a role of telomerase in the genome maintenance despite functional telomeres. Finally, we showed that the presence of more breaks in a cell favors the repair, leading to an increase of transmissible rearrangements. (author)

  18. Telomerase Activity and Telomerase Reverse Transcriptase Expression Induced by Selenium in Rat Hepatocytes

    Institute of Scientific and Technical Information of China (English)

    RI-AN YU; HUA-JIE CHEN; LING-FEI HE; BING CHEN; XUE-MIN CHEN

    2009-01-01

    Objectives To investigate the effects of sodium selenite on telomerase activity, apoptosis and expression of TERT, c-myc and p53 in rat hepatocytes. Methods Selenium at doses of 2.5, 5.0, and 10μmol/kg was given to SD rats by garage. In rat hepatocytes, telomerase activity was measured by the telomeric repeat amplification protocol (TRAP), apoptosis was detected by flow cytometry, and expressions of telomerase reverse transcriptase (TERT), c-myc and p53 were analyzed by reverse transcription-polymerase chain reaction (RT-PCR).c-Myc and P53 proteins were detected by immunochemistry. Results Selenium at doses of 2.5, 5.0, and 10μmol/kg significantly increased hepatocellular telomerase activity and induced apoptosis in a close-dependent manner. Although selenium at doses of 2.5, 5.0, and 10μmol/kg displayed no obvious enhancing effect on the TERT mRNA expression in rat hepatocytes (P>0.05), it significantly increased the c-myc mRNA and p53 mRNA expression at the dose of 10μmol/kg (p<0.05). Selenium at doses of 5.0 and 10μmol/kg obviously increased the content of P53 protein in rat hepatocytes, but only at the dose of 10μmol/kg, it significantly promoted the value of c-Myc protein in them. Conclusion Selenium can slightly increase telomerase activity and TERT expression, and significantly induce apoptosis and over-expression of c-myc and p53 at relatively high doses. The beneficial effects of selenium on senescence and aging may be mediated by telomerase activation and expression of TERT, c-myc, and p53 in rat hepatocytes.

  19. Correlation of Telomere Length and Telomerase Activity with Occult Ovarian Insufficiency

    OpenAIRE

    Butts, Samantha; Riethman, Harold; Ratcliffe, Sarah; Shaunik, Alka; Coutifaris, Christos; Barnhart, Kurt

    2009-01-01

    Background: Occult ovarian insufficiency is associated with infertility, impaired response to ovarian stimulation, and reduced live birth rates in women treated with assisted reproductive technologies. Although a decline in ovarian follicle number is expected with age, the proximate causes of occult ovarian insufficiency in young women remain poorly understood. Abnormalities in telomere length and telomerase activity in human granulosa cells may serve as molecular markers for this condition.

  20. Telomeric overhang length determines structural dynamics and accessibility to telomerase and ALT associated proteins

    OpenAIRE

    Hwang, Helen; Kreig, Alex; Calvert, Jacob; Lormand, Justin; Kwon, Yongho; Daley, James M.; Sung, Patrick; Opresko, Patricia L.; Myong, Sua

    2014-01-01

    The G-rich single stranded DNA at the 3′ end of human telomeres can self-fold into G-quaduplex (GQ). However, telomere lengthening by telomerase or the recombination-based alternative lengthening of telomere (ALT) mechanism requires protein loading on the overhang. Using single molecule fluorescence spectroscopy we discovered that lengthening the telomeric overhang also increased the rate of dynamic exchanges between structural conformations. Overhangs with five to seven TTAGGG repeats, compa...

  1. DNA damaging bystander signalling from stem cells, cancer cells and fibroblasts after Cr(VI) exposure and its dependence on telomerase

    International Nuclear Information System (INIS)

    The bystander effect is a feature of low dose radiation exposure and is characterized by a signaling process from irradiated cells to non irradiated cells, which causes DNA and chromosome damage in these 'nearest neighbour' cells. Here we show that a low and short dose of Cr(VI) can induce stem cells, cancer cells and fibroblasts to chronically secrete bystander signals, which cause DNA damage in neighboring cells. The Cr(VI) induced bystander signaling depended on the telomerase status of either cell. Telomerase negative fibroblasts were able to receive DNA damaging signals from telomerase positive or negative fibroblasts or telomerase positive cancer cells. However telomerase positive fibroblasts were resistant to signals from Cr(VI) exposed telomerase positive fibroblasts or cancer cells. Human embryonic stem cells, with positive Oct4 staining as a marker of pluripotency, showed no significant increase of DNA damage from adjacent Cr and mitomycin C exposed fibroblasts whilst those cells that were negatively stained did. This selectivity of DNA damaging bystander signaling could be an important consideration in developing therapies against cancer and in the safety and effectiveness of tissue engineering and transplantation using stem cells.

  2. DNA damaging bystander signalling from stem cells, cancer cells and fibroblasts after Cr(VI) exposure and its dependence on telomerase

    Energy Technology Data Exchange (ETDEWEB)

    Cogan, Nicola [Bristol Implant Research Centre, University of Bristol, Bristol, BS10 5NB (United Kingdom); Baird, Duncan M. [Department of Pathology School of Medicine, Cardiff University, Henry Wellcome Building for Biomedical Research in Wales, Heath Park, Cardiff, CF14 4XN (United Kingdom); Phillips, Ryan [Bristol Implant Research Centre, University of Bristol, Bristol, BS10 5NB (United Kingdom); Crompton, Lucy A.; Caldwell, Maeve A. [Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, BS1 3NY (United Kingdom); Rubio, Miguel A. [Center of Regenerative Medicine in Barcelona, CMRB Dr. Aiguader, 88, 7th Floor, 08003 Barcelona (Spain); Newson, Roger [Radiation and Environmental Science Centre, Focas Institute, Dublin Institute of Technology, Dublin 2 (Ireland); Lyng, Fiona [National Heart and Lung Institute, Imperial College London, London, SW7 2AZ (United Kingdom); Case, C. Patrick, E-mail: c.p.case@bristol.ac.uk [Bristol Implant Research Centre, University of Bristol, Bristol, BS10 5NB (United Kingdom)

    2010-01-05

    The bystander effect is a feature of low dose radiation exposure and is characterized by a signaling process from irradiated cells to non irradiated cells, which causes DNA and chromosome damage in these 'nearest neighbour' cells. Here we show that a low and short dose of Cr(VI) can induce stem cells, cancer cells and fibroblasts to chronically secrete bystander signals, which cause DNA damage in neighboring cells. The Cr(VI) induced bystander signaling depended on the telomerase status of either cell. Telomerase negative fibroblasts were able to receive DNA damaging signals from telomerase positive or negative fibroblasts or telomerase positive cancer cells. However telomerase positive fibroblasts were resistant to signals from Cr(VI) exposed telomerase positive fibroblasts or cancer cells. Human embryonic stem cells, with positive Oct4 staining as a marker of pluripotency, showed no significant increase of DNA damage from adjacent Cr and mitomycin C exposed fibroblasts whilst those cells that were negatively stained did. This selectivity of DNA damaging bystander signaling could be an important consideration in developing therapies against cancer and in the safety and effectiveness of tissue engineering and transplantation using stem cells.

  3. Activity of telomerase and telomeric length in Apis mellifera.

    Science.gov (United States)

    Korandová, Michala; Frydrychová, Radmila Čapková

    2016-06-01

    Telomerase is an enzyme that adds repeats of DNA sequences to the ends of chromosomes, thereby preventing their shortening. Telomerase activity is associated with proliferative status of cells, organismal development, and aging. We report an analysis of telomerase activity and telomere length in the honeybee, Apis mellifera. Telomerase activity was found to be regulated in a development and caste-specific manner. During the development of somatic tissues of larval drones and workers, telomerase activity declined to 10 % of its level in embryos and remained low during pupal and adult stages but was upregulated in testes of late pupae, where it reached 70 % of the embryo level. Upregulation of telomerase activity was observed in the ovaries of late pupal queens, reaching 160 % of the level in embryos. Compared to workers and drones, queens displayed higher levels of telomerase activity. In the third larval instar of queens, telomerase activity reached the embryo level, and an enormous increase was observed in adult brains of queens, showing a 70-fold increase compared to a brain of an adult worker. Southern hybridization of terminal TTAGG fragments revealed a high variability of telomeric length between different individuals, although the same pattern of hybridization signals was observed in different tissues of each individual. PMID:26490169

  4. Immortalization of porcine placental trophoblast cells through reconstitution of telomerase activity.

    Science.gov (United States)

    Zhang, Hongling; Huang, Yong; Wang, Lili; Yu, Tingting; Wang, Zengguo; Chang, Lingling; Zhao, Xiaomin; Luo, Xiaomao; Zhang, Liang; Tong, Dewen

    2016-05-01

    Placental trophoblast cells (PTCs) play a critical role in histotrophic nutrient absorption, gaseous exchange, endocrine activities, and barrier function between the maternal and fetal systems. Establishment of immortalized porcine PTCs will help us to investigate the potential effects of different viruses on porcine trophoblast. In the present study, primary porcine PTCs were isolated from healthy gilts at Day 30 to Day 50 of gestation through collagenase digestion, percoll gradient centrifugation, and anti-CD9 immunomagnetic negative selection. To provide stable and long lifespan cells, primary PTCs were transfected with human telomerase reverse transcriptase (hTERT) gene. One porcine placental trophoblast cell line, named as hTERT-PTCs, was chosen for characterization. Human telomerase reverse transcriptase-PTCs achieved an extended replicative lifespan without exhibiting any neoplastic transformation signs in vivo or in vitro. The morphologic and key physiological characteristics of the immortalized PTCs were similar to primary PTCs. The immortalized PTCs retained original cell polarity and normal karyotype, expressed trophoblast-specific marker cytokeratin 7 and E-cadherin but did not express vimentin and major histocompatibility complex class I antigens as well as primary PTCs. Human telomerase reverse transcriptase-PTCs secreted low levels of chorionic gonadotrophin β-subunit and placental lactogen that were coincident with primary PTCs. Taken together, our results demonstrated that the porcine PTCs could be immortalized through reconstitution of telomerase activity. The immortalized PTCs maintained its original characteristics and can be used as a model cells line to study the pathologic changes of porcine placental trophoblast in viruses infectious diseases. PMID:26850465

  5. A Triple Helix within a Pseudoknot Is a Conserved and Essential Element of Telomerase RNA▿

    OpenAIRE

    Shefer, Kinneret; Brown, Yogev; Gorkovoy, Valentin; Nussbaum, Tamar; Ulyanov, Nikolai B.; Tzfati, Yehuda

    2007-01-01

    Telomerase copies a short template within its integral telomerase RNA onto eukaryotic chromosome ends, compensating for incomplete replication and degradation. Telomerase action extends the proliferative potential of cells, and thus it is implicated in cancer and aging. Nontemplate regions of telomerase RNA are also crucial for telomerase function. However, they are highly divergent in sequence among species, and their roles are largely unclear. Using in silico three-dimensional modeling, con...

  6. Specific RNA residue interactions required for enzymatic functions of Tetrahymena telomerase.

    OpenAIRE

    Gilley, D; Blackburn, E H

    1996-01-01

    The ribonucleoprotein enzyme telomerase is a specialized reverse transcriptase that synthesizes telomeric DNA by copying a template sequence within the telomerase RNA. Here we analyze the actions of telomerase from Tetrahymena thermophila assembled in vivo with mutated or wild-type telomerase RNA to define further the roles of particular telomerase RNA residues involved in essential enzymatic functions: templating, substrate alignment, and promotion of polymerization. Position 49 of the telom...

  7. Evalution of gene expression of the human telomerase gene in the screating of cervical lesions%hTERC基因表达在宫颈病变筛查中的意义

    Institute of Scientific and Technical Information of China (English)

    周波; 李婷; 周晨; 陈忠东; 谢宛玉

    2011-01-01

    Objective: To investigate the human telomerase RNA (hTERC) gene in the screating of cervical lesions. Methods; Hie expression of hTERC gene of cervix cytologic samples were detectded by using fluorescence in situ hybridization ( FISH) . According to histology biopsy 115 Pap smears were divided into cervinl intraepithelial neoplasin ( CIN, n =69), squamous carcinomal of the cervix (SCC, n=26) . Normnl (n =20) . Results: The positive rate of hTERC gene in CIN I , CIN Ⅱ, CIN Ⅲand SCC were respectively 22. 00% , 75. 00% , 100.00%and 100. 00% (P <0.05) . hTERC gene copy numbers in CINIⅡ/CINⅢ/SCC were significantly higher than that in CIN I. The number of abnormal cells were increased in gene amplification for hTERC , CIN I was 6.50% , CINⅡ was 25. 50% , CIN Ⅲ was 30. 60% , SCC was 50. 80% (P <0.05) . The abnormal hTERC signal types of 2:3 founded in CIN I was 60.00% , in CIN Ⅱ, CIN Ⅲ and SCC were 47.10% , 45.18% and 36.44% respectively. In SCC, the abnormal hTERC signal types were 4:4 and 5 : 5 mainly. Conclusion: The increase of hTERC expression in the invasive CIN and SCC, the copy numbers are associated with the severity of cytologic and histologic findings. Therefore can as a screening detection index of biometrical genetics for progress of cervical anterior lesions.%目的:探讨人端粒酶RNA (hTERC)基因在宫颈病变筛查中的临床意义.方法:收集2008年1月~11月南华大学第一附属医院115例妇女宫颈脱落细胞标本,病理学检查确诊CIN患者69例,宫颈鳞癌(SCC)患者26例,正常细胞学妇女20例.用荧光原位杂交(FISH)方法检测脱落细胞hTERC基因的表达.结果:①hTERC基因在CIN Ⅰ、CINⅡ、CINⅢ及SCC患者宫颈脱落细胞中的阳性表达率分别是22.00%、75.00%、100.00%和100.00%.CIN Ⅰ、CINⅡ、CINⅢ和SCC组与正常组比较,hTERC基因阳性率差异有统计学意义(P<0.05).其中CIN Ⅰ与CINⅡ、CINⅢ比较,CIN Ⅰ与SCC比较差异有统计学意义(P<0

  8. Functional and mechanistic analysis of telomerase: An antitumor drug target.

    Science.gov (United States)

    Chen, Yinnan; Zhang, Yanmin

    2016-07-01

    The current research on anticancer drugs focuses on exploiting particular traits or hallmarks unique to cancer cells. Telomerase, a special reverse transcriptase, has been recognized as a common factor in most tumor cells, and in turn a distinctive characteristic with respect to non-malignant cells. This feature has made telomerase a preferred target for anticancer drug development and cancer therapy. This review aims to analyze the pharmacological function and mechanism and role of telomerase in oncogenesis; to provide fundamental knowledge for research on the structure, function, and working mechanism of telomerase; to expound the role that telomerase plays in the initiation and development of tumor and its relationship with tumor cell growth, proliferation, apoptosis, and related pathway molecules; and to display potential targets of antitumor drug for inhibiting the expression, reconstitution, and trafficking of the enzyme. We therefore summarize recent advances in potential telomerase inhibitors for antitumor including natural products, synthetic small molecules, peptides and proteins, which indicate that optimizing the delivery method and drug combination could be of help in a combinatorial drug treatment for tumor. More extensive understanding of the structure, biogenesis, and mechanism of telomerase will provide invaluable information for increasing the efficiency of rational antitumor drug design. PMID:27118336

  9. Telomerase RNA is more than a DNA template.

    Science.gov (United States)

    Webb, Christopher J; Zakian, Virginia A

    2016-08-01

    The addition of telomeric DNA to chromosome ends is an essential cellular activity that compensates for the loss of genomic DNA that is due to the inability of the conventional DNA replication apparatus to duplicate the entire chromosome. The telomerase reverse transcriptase and its associated RNA bind to the very end of the telomere via a sequence in the RNA and specific protein-protein interactions. Telomerase RNA also provides the template for addition of new telomeric repeats by the reverse-transcriptase protein subunit. In addition to the template, there are 3 other conserved regions in telomerase RNA that are essential for normal telomerase activity. Here we briefly review the conserved core regions of telomerase RNA and then focus on a recent study in fission yeast that determined the function of another conserved region in telomerase RNA called the Stem Terminus Element (STE). (1) The STE is distant from the templating core of telomerase in both the linear and RNA secondary structure, but, nonetheless, affects the fidelity of telomere sequence addition and, in turn, the ability of telomere binding proteins to bind and protect chromosome ends. We will discuss possible mechanisms of STE action and the suitability of the STE as an anti-cancer target. PMID:27245259

  10. Association of telomerase activity with radio- and chemosensitivity of neuroblastomas

    International Nuclear Information System (INIS)

    Telomerase activity compensates shortening of telomeres during cell division and enables cancer cells to escape senescent processes. It is also supposed, that telomerase is associated with radio- and chemoresistance. In the here described study we systematically investigated the influence of telomerase activity (TA) and telomere length on the outcome of radio- and chemotherapy in neuroblastoma. We studied the effects on dominant negative (DN) mutant, wild type (WT) of the telomerase catalytic unit (hTERT) using neuroblastoma cell lines. The cells were irradiated with 60Co and treated with doxorubicin, etoposide, cisplatin and ifosfamide, respectively. Viability was determined by MTS/MTT-test and the GI50 was calculated. Telomere length was measured by southernblot analysis and TA by Trap-Assay. Compared to the hTERT expressing cells the dominant negative cells showed increased radiosensitivity with decreased telomere length. Independent of telomere length, telomerase negative cells are significantly more sensitive to irradiation. The effect of TA knock-down or overexpression on chemosensitivity were dependent on TA, the anticancer drug, and the chemosensitivity of the maternal cell line. Our results supported the concept of telomerase inhibition as an antiproliferative treatment approach in neuroblastomas. Telomerase inhibition increases the outcome of radiotherapy while in combination with chemotherapy the outcome depends on drug- and cell line and can be additive/synergistic or antagonistic. High telomerase activity is one distinct cancer stem cell feature and the here described cellular constructs in combination with stem cell markers like CD133, Aldehyddehydrogenase-1 (ALDH-1) or Side population (SP) may help to investigate the impact of telomerase activity on cancer stem cell survival under therapy

  11. Topoisomerase II inhibition suppresses the proliferation of telomerase-negative cancers.

    Science.gov (United States)

    Hsieh, Meng-Hsun; Tsai, Cheng-Hui; Lin, Chuan-Chuan; Li, Tsai-Kun; Hung, Ting-Wei; Chang, Li-Te; Hsin, Ling-Wei; Teng, Shu-Chun

    2015-05-01

    Telomere maintenance is required for chromosome stability, and telomeres are typically elongated by telomerase following DNA replication. In both tumor and yeast cells that lack telomerase, telomeres are maintained via an alternative recombination mechanism. Previous studies have indicated that yeast Sgs1 and Top3 may work together to remove highly negative supercoils that are generated from recombination. However, the mechanism by which cells eradicate highly positive supercoils during recombination remains unclear. In the present study, we demonstrate that TOP2 is involved in telomere-telomere recombination. Disturbance of telomeric structure by RIF1 or RIF2 deletion alleviates the requirement for TOP2 in telomere-telomere recombination. In human telomerase-negative alternative lengthening of telomere (ALT) cells, TOP2α or TOP2β knockdown decreases ALT-associated PML bodies, increases telomere dysfunction-induced foci and triggers telomere shortening. Similar results were observed when ALT cells were treated with ICRF-193, a TOP2 inhibitor. Importantly, ICRF-193 treatment blocks ALT-associated phenotypes in vitro, causes telomere shortening, and inhibits ALT cell proliferation in mice. Taken together, these findings imply that TOP2 is involved in the ALT pathway, perhaps by resolving the highly positive supercoil structure at the front of the helicase. Inhibition of topoisomerase II may be a promising therapeutic approach that can be used to prevent cell proliferation in ALT-type cancer cells. PMID:25430478

  12. Aminoacyl-anthraquinone conjugates as telomerase inhibitors: synthesis, biophysical and biological evaluation.

    Science.gov (United States)

    Zagotto, Giuseppe; Sissi, Claudia; Lucatello, Lorena; Pivetta, Claudia; Cadamuro, Sergio A; Fox, Keith R; Neidle, Stephen; Palumbo, Manlio

    2008-09-25

    The telomerase-telomere complex is a prospective anticancer target. To inhibit enzyme activity by induction of G-quadruplex in human telomeres, we have synthesized a small library of 2,6- and 2,7-amino-acyl/ peptidyl anthraquinones with diverse connecting linkers, charge, lipophilicity and bulk. The test compounds modulated G-quadruplex stability to different extents and showed clear preference for quadruplex over duplex DNA. Telomerase inhibition correlated with G-quadruplex stabilization. A SAR analysis showed that type of linkage between the linker and the anthraquinone, together with the position of the side chains and the nature of the amino acid components play a major role both in stabilizing G-quadruplex and producing telomerase inhibition. Short-term cytotoxic activity was poor. However, after prolonged exposure to effective G-quadruplex binders, cells became senescent. These results are of help in the rational design of more efficient G-quadruplex stabilizers, possibly endowed with cancer cell-selective antiproliferative effects. PMID:18754611

  13. Telomere stability and telomerase in mesenchymal stem cells

    DEFF Research Database (Denmark)

    Serakinci, Nedime; Graakjaer, Jesper; Kølvrå, Steen

    2008-01-01

    Telomeres are repetitive genetic material that cap and thereby protect the ends of chromosomes. Each time a cell divides, telomeres get shorter. Telomere length is mainly maintained by telomerase. This enzyme is present in high concentrations in the embryonic stem cells and in fast growing...... embryonic cells, and declines with age. It is still unclear to what extent there is telomerase in adult stem cells, but since these are the founder cells of cells of all the tissues in the body, understanding the telomere dynamics and expression of telomerase in adult stem cells is very important. In the...

  14. Investigation of Telomerase/Telomeres system in Bone Marrow Mesenchymal Stem Cells derived from IPF and RA-UIP

    Directory of Open Access Journals (Sweden)

    Antoniou Katerina M

    2012-07-01

    Full Text Available Abstract Objective Idiopathic Pulmonary Fibrosis and Rheumatoid Arthritis associated usual interstitial pneumonia seem to have the same poor outcome as there is not an effective treatment. The aim of the study is to explore the reparative ability of bone marrow mesenchymal stem cells by evaluating the system telomerase/telomeres and propose a novel therapeutic approach. Methods BM-MSCs were studied in 6 IPF patients, 7 patients with RA-UIP and 6 healthy controls. We evaluated the telomere length as well as the mRNA expression of both components of telomerase (human telomerase reverse transcriptase, h-TERT and RNA template complementary to the telomeric loss DNA, h-TERC. Results We found that BM-MSCs from IPF, RA-UIP cases do not present smaller telomere length than the controls (p = 0.170. There was no significant difference regarding the expression of both h-TERT and h-TERC genes between patients and healthy controls (p = 0.107 and p = 0.634 respectively. Conclusions We demonstrated same telomere length and telomerase expression in BM-MSCs of both IPF and RA-UIP which could explain similarities in pathogenesis and prognosis. Maintenance of telomere length in these cells could have future implication in cell replacement treatment with stem cells of these devastating lung disorders.

  15. Long telomeres produced by telomerase-resistant recombination are established from a single source and are subject to extreme sequence scrambling.

    Directory of Open Access Journals (Sweden)

    Jianing Xu

    Full Text Available Considerable evidence now supports the idea that the moderate telomere lengthening produced by recombinational telomere elongation (RTE in a Kluyveromyces lactis telomerase deletion mutant occurs through a roll-and-spread mechanism. However, it is unclear whether this mechanism can account for other forms of RTE that produce much longer telomeres such as are seen in human alternative lengthening of telomere (ALT cells or in the telomerase-resistant type IIR "runaway" RTE such as occurs in the K. lactis stn1-M1 mutant. In this study we have used mutationally tagged telomeres to examine the mechanism of RTE in an stn1-M1 mutant both with and without telomerase. Our results suggest that the establishment stage of the mutant state in newly generated stn1-M1 ter1-Δ mutants surprisingly involves a first stage of sudden telomere shortening. Our data also show that, as predicted by the roll-and-spread mechanism, all lengthened telomeres in a newly established mutant cell commonly emerge from a single telomere source. However, in sharp contrast to the RTE of telomerase deletion survivors, we show that the RTE of stn1-M1 ter1-Δ cells produces telomeres whose sequences undergo continuous intense scrambling via recombination. While telomerase was not necessary for the long telomeres in stn1-M1 cells, its presence during their establishment was seen to interfere with the amplification of repeats via recombination, a result consistent with telomerase retaining its ability to add repeats during active RTE. Finally, we observed that the presence of active mismatch repair or telomerase had important influences on telomeric amplification and/or instability.

  16. Telomerase expression is sufficient for chromosomal integrity in cells lacking p53 dependent G1 checkpoint function

    Directory of Open Access Journals (Sweden)

    Simpson Dennis

    2005-01-01

    Full Text Available Abstract Background Secondary cultures of human fibroblasts display a finite lifespan ending at senescence. Loss of p53 function by mutation or viral oncogene expression bypasses senescence, allowing cell division to continue for an additional 10 – 20 doublings. During this time chromosomal aberrations seen in mitotic cells increase while DNA damage and decatenation checkpoint functions in G2 cells decrease. Methods To explore this complex interplay between chromosomal instability and checkpoint dysfunction, human fibroblast lines were derived that expressed HPV16E6 oncoprotein or dominant-negative alleles of p53 (A143V and H179Q with or without the catalytic subunit of telomerase. Results Cells with normal p53 function displayed 86 – 93% G1 arrest after exposure to 1.5 Gy ionizing radiation (IR. Expression of HPV16E6 or p53-H179Q severely attenuated G1 checkpoint function (3 – 20% arrest while p53-A143V expression induced intermediate attenuation (55 – 57% arrest irrespective of telomerase expression. All cell lines, regardless of telomerase expression or p53 status, exhibited a normal DNA damage G2 checkpoint response following exposure to 1.5 Gy IR prior to the senescence checkpoint. As telomerase-negative cells bypassed senescence, the frequencies of chromosomal aberrations increased generally congruent with attenuation of G2 checkpoint function. Telomerase expression allowed cells with defective p53 function to grow >175 doublings without chromosomal aberrations or attenuation of G2 checkpoint function. Conclusion Thus, chromosomal instability in cells with defective p53 function appears to depend upon telomere erosion not loss of the DNA damage induced G1 checkpoint.

  17. Role of Mitochondrial Translocation of Telomerase in Hepatocellular Carcinoma Cells with Multidrug Resistance

    OpenAIRE

    Ling, Xianlong; Wen, Lei; Zhou, Yuan

    2012-01-01

    Multidrug resistance (MDR) is a major obstacle of cancer chemotherapy. This study aimed to investigate the role of mitochondrial translocation of telomerase (hTERT) in MDR of human hepatocellular carcinoma (HCC) cells. In this study, three HCC cell lines (SK-Hep1/CDDP1 cells, SK-Hep1/CDDP2 cells and SK-Hep1/CDDP3 cells) with differential resistance index (RI) to cisplatin (CDDP) were induced by pulse treatment of SK-Hep1 (human hepatocellular cell line) with CDDP in vitro. The RI of SK-Hep1/C...

  18. Telomerase reverse transcriptase promoter mutations in bladder cancer

    DEFF Research Database (Denmark)

    Allory, Yves; Beukers, Willemien; Sagrera, Ana;

    2014-01-01

    BACKGROUND: Hotspot mutations in the promoter of the gene coding for telomerase reverse transcriptase (TERT) have been described and proposed to activate gene expression. OBJECTIVES: To investigate TERT mutation frequency, spectrum, association with expression and clinical outcome, and potential...

  19. Early Telomerase Inactivation Accelerates Aging Independently of Telomere Length

    OpenAIRE

    Xie, Zhengwei; Jay, Kyle A.; Smith, Dana L.; Zhang, Yi; Liu, Zairan; Zheng, Jiashun; Tian, Ruilin; Li, Hao; Blackburn, Elizabeth

    2015-01-01

    Telomerase is required for long-term telomere maintenance and protection. Using single budding yeast mother cell analyses we found that, even Early after Telomerase Inactivation (ETI), yeast mother cells show transient DNA Damage Response (DDR) episodes, stochastically altered cell cycle dynamics, and accelerated mother cell aging. The acceleration of ETI mother cell aging was not explained by increased reactive oxygen species (ROS), Sir protein perturbation, or deprotected telomeres. ETI occ...

  20. Telomerase as a Cancer Target. Development of New Molecules.

    Science.gov (United States)

    Gomez, D L Mengual; Armando, R G; Cerrudo, C S; Ghiringhelli, P D; Gomez, D E

    2016-01-01

    Telomeres are the terminal part of the chromosome containing a long repetitive and noncodifying sequence that has as function protecting the chromosomes. In normal cells, telomeres lost part of such repetitive sequence in each mitosis, until telomeres reach a critical point, triggering at that time senescence and cell death. However, in most of tumor cells in each cell division a part of the telomere is lost, however the appearance of an enzyme called telomerase synthetize the segment that just has been lost, therefore conferring to tumor cells the immortality hallmark. Telomerase is significantly overexpressed in 80-95% of all malignant tumors, being present at low levels in few normal cells, mostly stem cells. Due to these characteristics, telomerase has become an attractive target for new and more effective anticancer agents. The capability of inhibiting telomerase in tumor cells should lead to telomere shortening, senescence and apoptosis. In this work, we analyze the different strategies for telomerase inhibition, either in development, preclinical or clinical stages taking into account their strong points and their caveats. We covered strategies such as nucleosides analogs, oligonucleotides, small molecule inhibitors, G-quadruplex stabilizers, immunotherapy, gene therapy, molecules that affect the telomere/ telomerase associated proteins, agents from microbial sources, among others, providing a balanced evaluation of the status of the inhibitors of this powerful target together with an analysis of the challenges ahead. PMID:26873194

  1. Telomerase as a Cancer Target. Development of New Molecules

    Science.gov (United States)

    Gomez, D.L. Mengual; Armando, R.G.; Cerrudo, C.S.; Ghiringhelli, P.D.; Gomez, D.E.

    2016-01-01

    Telomeres are the terminal part of the chromosome containing a long repetitive and non-codifying sequence that has as function protecting the chromosomes. In normal cells, telomeres lost part of such repetitive sequence in each mitosis, until telomeres reach a critical point, triggering at that time senescence and cell death. However, in most of tumor cells in each cell division a part of the telomere is lost, however the appearance of an enzyme called telomerase synthetize the segment that just has been lost, therefore conferring to tumor cells the immortality hallmark. Telomerase is significantly overexpressed in 80–95% of all malignant tumors, being present at low levels in few normal cells, mostly stem cells. Due to these characteristics, telomerase has become an attractive target for new and more effective anticancer agents. The capability of inhibiting telomerase in tumor cells should lead to telomere shortening, senescence and apoptosis. In this work, we analyze the different strategies for telomerase inhibition, either in development, preclinical or clinical stages taking into account their strong points and their caveats. We covered strategies such as nucleosides analogs, oligonucleotides, small molecule inhibitors, G-quadruplex stabilizers, immunotherapy, gene therapy, molecules that affect the telomere/telomerase associated proteins, agents from microbial sources, among others, providing a balanced evaluation of the status of the inhibitors of this powerful target together with an analysis of the challenges ahead. PMID:26873194

  2. Aneuploidy as a mechanism of adaptation to telomerase insufficiency.

    Science.gov (United States)

    Millet, Caroline; Makovets, Svetlana

    2016-08-01

    Cells' survival is determined by their ability to adapt to constantly changing environment. Adaptation responses involve global changes in transcription, translation, and posttranslational modifications of proteins. In recent years, karyotype changes in adapting populations of single cell organisms have been reported in a number of studies. More recently, we have described aneuploidy as an adaptation mechanism used by populations of budding yeast Saccharomyces cerevisiae to survive telomerase insufficiency induced by elevated growth temperature. Genetic evidence suggests that telomerase insufficiency is caused by decreased levels of the telomerase catalytic subunit Est2. Here, we present experiments arguing that the underlying cause of this phenomenon may be within the telomerase RNA TLC1: changes in the expression of TLC1 as well as mutations in the TLC1 template region affect telomere length equilibrium and the temperature threshold for the induction of telomerase insufficiency. We discuss what lies at the root of telomerase insufficiency, how cell populations overcome it through aneuploidy and whether reversible aneuploidy could be an adaptation mechanism for a variety of environmental stresses. PMID:26758992

  3. The β-carboline alkaloid harmine inhibits telomerase activity of MCF-7 cells by down-regulating hTERT mRNA expression accompanied by an accelerated senescent phenotype

    Directory of Open Access Journals (Sweden)

    Lei Zhao

    2013-10-01

    Full Text Available The end replication problem, which occurs in normal somatic cells inducing replicative senescence, is solved in most cancer cells by activating telomerase. The activity of telomerase is highly associated with carcinogenesis which makes the enzyme an attractive biomarker in cancer diagnosis and treatment. The indole alkaloid harmine has multiple pharmacological properties including DNA intercalation which can lead to frame shift mutations. In this study, harmine was applied to human breast cancer MCF-7 cells. Its activity towards telomerase was analyzed by utilizing the telomeric repeat amplification protocol (TRAP. Our data indicate that harmine exhibits a pronounced cytotoxicity and induces an anti-proliferation state in MCF-7 cells which is accompanied by a significant inhibition of telomerase activity and an induction of an accelerated senescence phenotype by over-expressing elements of the p53/p21 pathway.

  4. Design and development of PCR-free highly sensitive electrochemical assay for detection of telomerase activity using Nano-based (liposomal) signal amplification platform.

    Science.gov (United States)

    Alizadeh-Ghodsi, Mohammadreza; Zavari-Nematabad, Ali; Hamishehkar, Hamed; Akbarzadeh, Abolfazl; Mahmoudi-Badiki, Tohid; Zarghami, Faraz; Pourhassan Moghaddam, Mohammad; Alipour, Esmaeel; Zarghami, Nosratollah

    2016-06-15

    Telomerase, which has been detected in almost all kinds of cancer tissues, is considered as an important tumor marker for early cancer diagnostics. In the present study, an electrochemical method based on liposomal signal amplification platform is proposed for simple, PCR-free, and highly sensitive detection of human telomerase activity, extracted from A549 cells. In this strategy, telomerase reaction products, which immobilized on streptavidin-coated microplate, hybridized with biotinylated capture probes. Then, dopamine-loaded biotinylated liposomes are attached through streptavidin to biotinylated capture probes. Finally, liposomes are ruptured by methanol and the released-dopamine is subsequently measured using differential pulse voltammetry technique by multi-walled carbon nanotubes modified glassy carbon electrode. Using this strategy, the telomerase activity extracted from 10 cultured cancer cells could be detected. Therefore, this approach affords high sensitivity for telomerase activity detection and it can be regarded as an alternative to telomeric repeat amplification protocol assay, having the advantages of simplicity and less assay time. PMID:26874110

  5. Suppression of telomere-binding protein TPP1 resulted in telomere dysfunction and enhanced radiation sensitivity in telomerase-negative osteosarcoma cell line

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Weiguang [Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan (China); Department of Oncology, The Third Affiliated Hospital, Soochow University, Changzhou (China); Wu, Qinqin [Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan (China); Department of Radiation Oncology, Changzhou Tumor Hospital, Soochow University, Changzhou (China); Zhou, Fuxiang; Xie, Conghua [Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan (China); Wu, Changping, E-mail: wcpzlk@163.com [Department of Oncology, The Third Affiliated Hospital, Soochow University, Changzhou (China); Zhou, Yunfeng, E-mail: yfzhouwhu@163.com [Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan (China)

    2014-03-07

    Highlights: • Down-regulation of TPP1 shortened telomere length in telomerase-negative cells. • Down-regulation of TPP1 induced cell apoptosis in telomerase-negative cells. • Down-regulation of TPP1 increased radiosensitivity in telomerase-negative cells. - Abstract: Mammalian telomeres are protected by the shelterin complex that contains the six core proteins POT1, TPP1, TIN2, TRF1, TRF2 and RAP1. TPP1, formerly known as TINT1, PTOP, and PIP1, is a key factor that regulates telomerase recruitment and activity. In addition to this, TPP1 is required to mediate the shelterin assembly and stabilize telomere. Previous work has found that TPP1 expression was elevated in radioresistant cells and that overexpression of TPP1 led to radioresistance and telomere lengthening in telomerase-positive cells. However, the exact effects and mechanism of TPP1 on radiosensitivity are yet to be precisely defined in the ALT cells. Here we report on the phenotypes of the conditional deletion of TPP1 from the human osteosarcoma U2OS cells using ALT pathway to extend the telomeres.TPP1 deletion resulted in telomere shortening, increased apoptosis and radiation sensitivity enhancement. Together, our findings show that TPP1 plays a vital role in telomere maintenance and protection and establish an intimate relationship between TPP1, telomere and cellular response to ionizing radiation, but likely has the specific mechanism yet to be defined.

  6. Herpesvirus telomerase RNA (vTR with a mutated template sequence abrogates herpesvirus-induced lymphomagenesis.

    Directory of Open Access Journals (Sweden)

    Benedikt B Kaufer

    2011-10-01

    Full Text Available Telomerase reverse transcriptase (TERT and telomerase RNA (TR represent the enzymatically active components of telomerase. In the complex, TR provides the template for the addition of telomeric repeats to telomeres, a protective structure at the end of linear chromosomes. Human TR with a mutation in the template region has been previously shown to inhibit proliferation of cancer cells in vitro. In this report, we examined the effects of a mutation in the template of a virus encoded TR (vTR on herpesvirus-induced tumorigenesis in vivo. For this purpose, we used the oncogenic avian herpesvirus Marek's disease virus (MDV as a natural virus-host model for lymphomagenesis. We generated recombinant MDV in which the vTR template sequence was mutated from AATCCCAATC to ATATATATAT (vAU5 by two-step Red-mediated mutagenesis. Recombinant viruses harboring the template mutation replicated with kinetics comparable to parental and revertant viruses in vitro. However, mutation of the vTR template sequence completely abrogated virus-induced tumor formation in vivo, although the virus was able to undergo low-level lytic replication. To confirm that the absence of tumors was dependent on the presence of mutant vTR in the telomerase complex, a second mutation was introduced in vAU5 that targeted the P6.1 stem loop, a conserved region essential for vTR-TERT interaction. Absence of vTR-AU5 from the telomerase complex restored virus-induced lymphoma formation. To test if the attenuated vAU5 could be used as an effective vaccine against MDV, we performed vaccination-challenge studies and determined that vaccination with vAU5 completely protected chickens from lethal challenge with highly virulent MDV. Taken together, our results demonstrate 1 that mutation of the vTR template sequence can completely abrogate virus-induced tumorigenesis, likely by the inhibition of cancer cell proliferation, and 2 that this strategy could be used to generate novel vaccine candidates

  7. Immortalization of human myogenic progenitor cell clone retaining multipotentiality

    International Nuclear Information System (INIS)

    Human myogenic cells have limited ability to proliferate in culture. Although forced expression of telomerase can immortalize some cell types, telomerase alone delays senescence of human primary cultured myogenic cells, but fails to immortalize them. In contrast, constitutive expression of both telomerase and the E7 gene from human papillomavirus type 16 immortalizes primary human myogenic cells. We have established an immortalized primary human myogenic cell line preserving multipotentiality by ectopic expression of telomerase and E7. The immortalized human myogenic cells exhibit the phenotypic characteristics of their primary parent, including an ability to undergo myogenic, osteogenic, and adipogenic terminal differentiation under appropriate culture conditions. The immortalized cells will be useful for both basic and applied studies aimed at human muscle disorders. Furthermore, immortalization by transduction of telomerase and E7 represents a useful method by which to expand human myogenic cells in vitro without compromising their ability to differentiate

  8. BLOOD TELOMERASE ACTIVITY AND ITS CORRELATIVITY WITH NON-SMALL CELL LUNG CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    胡坚; 李任远; 孙骊; 倪一鸣

    2004-01-01

    Objective: To study the correlativity between blood telomerase activity and Non-small cell lung carcinoma (NSCLC) through relative quantitative analysis of telomerase activity. Methods: Thirty-eight NSCLC and 25 inpatients with benign lung disease were selected. Telomerase repeat amplification protocol was adopted. PCR products were assayed with ELISA. Results: (a) Blood telomerase activity during operation was higher than that before or after operation (P0.05). (c) Blood telomerase activity of adenocarcinoma during and after operation was higher than that before operation (P0.05). Conclusion: The qualitative assay of blood telomerase activity can be adopted as an assistant index for diagnosis of NSCLC. Postoperative blood telomerase activity of adenocarcinoma is higher than that of squamous carcinoma. It may be an evidence for the likelihood of adenocarcinoma to metastase through blood. Blood telomerase activity increases significantly during operation, suggesting that operation may cause more cancer cells entering into circulation.

  9. Ataxia telangiectasia mutated (Atm) is not required for telomerase-mediated elongation of short telomeres

    OpenAIRE

    Feldser, David; Strong, Margaret A.; Greider, Carol W

    2006-01-01

    Telomerase-mediated telomere addition counteracts telomere shortening due to incomplete DNA replication. Short telomeres are the preferred substrate for telomere addition by telomerase; however, the mechanism by which telomerase recognizes short telomeres is unclear. In yeast, the Ataxia telangiectasia mutated (Atm) homolog, Tel1, is necessary for normal telomere length regulation likely by altering telomere structure, allowing telomerase recruitment to short telomeres. To examine the role of...

  10. A TIN2 dyskeratosis congenita mutation causes telomerase-independent telomere shortening in mice

    OpenAIRE

    Frescas, David; de Lange, Titia

    2014-01-01

    The progressive bone marrow failure syndrome dyskeratosis congenita (DC) is often caused by mutations in telomerase or factors involved in telomerase biogenesis and trafficking. However, a subset of DC patients is heterozygous for mutations in the shelterin component TIN2. Here, heterozygous TIN2-DC mice showed a telomere-shortening phenotype in both telomerase-proficient and telomerase-deficient backgrounds. This study raises the possibility that some of the TIN2-DC mutations may affect telo...

  11. The Pif1 Helicase, a Negative Regulator of Telomerase, Acts Preferentially at Long Telomeres

    OpenAIRE

    Jane A Phillips; Angela Chan; Katrin Paeschke; Zakian, Virginia A.

    2015-01-01

    Telomerase, the enzyme that maintains telomeres, preferentially lengthens short telomeres. The S. cerevisiae Pif1 DNA helicase inhibits both telomerase-mediated telomere lengthening and de novo telomere addition at double strand breaks (DSB). Here, we report that the association of the telomerase subunits Est2 and Est1 at a DSB was increased in the absence of Pif1, as it is at telomeres, suggesting that Pif1 suppresses de novo telomere addition by removing telomerase from the break. To determ...

  12. Telomerase-Deficient Mice Exhibit Bone Loss Owing to Defects in Osteoblasts and Increased Osteoclastogenesis by Inflammatory Microenvironment

    DEFF Research Database (Denmark)

    Saeed, H.; Abdallah, B. M.; Ditzel, N.;

    2011-01-01

    Telomere shortening owing to telomerase deficiency leads to accelerated senescence of human skeletal (mesenchymal) stem cells (MSCs) in vitro, whereas overexpression leads to telomere elongation, extended life span, and enhanced bone formation. To study the role of telomere shortening in vivo, we...... osteoblastic defects and creation of a proinflammatory osteoclast-activating microenvironment. Thus telonnerization of MSCs may provide a novel approach for abolishing age-related bone loss. (C) 2011 American Society for Bone and Mineral Research....

  13. Mesenchymal stem cells with high telomerase expression do not actively restore their chromosome arm specific telomere length pattern after exposure to ionizing radiation

    DEFF Research Database (Denmark)

    Graakjaer, Jesper; Christensen, Rikke; Kølvrå, Steen;

    2007-01-01

    investigate the existence and maintenance of the telomere length pattern in stem cells. For this aim we studied telomere length in primary human mesenchymal stem cells (hMSC) and their telomerase-immortalised counterpart (hMSC-telo1) during extended proliferation as well as after irradiation. Telomere lengths...

  14. Telomerase in relation to clinicopathologic prognostic factors and survival in cervical cancer

    NARCIS (Netherlands)

    Wisman, GBA; Knol, AJ; Helder, MN; Krans, M; de Vries, EGE; Hollema, H; de Jong, S; van der Zee, AGJ

    2001-01-01

    We investigated, in cervical cancer, the relation between telomerase activity, telomerase RNA (hTR) and mRNA of the catalytic subunit of telomerase, hTERT, with "classic" clinicopathological factors as well as survival. Frozen specimens were obtained from 107 consecutive patients with cervical cance

  15. Impaired telomerase activity hinders proliferation and in vitro transformation of Penaeus monodon lymphoid cells.

    Science.gov (United States)

    Jayesh, P; Vrinda, S; Priyaja, P; Philip, Rosamma; Singh, I S Bright

    2016-08-01

    Retaining terminal transferase activity of telomerase, the ribonucleoprotein enzyme which add telomeric repeats on chromosome end is thought to be required to prevent cellular ageing. Additionally, telomerase considered as a marker for cell proliferation and immortalization in eukaryotes. We examined telomerase activity in tissues and lymphoid cell culture of Penaeus monodon. Along with telomerase activity, telomere repeats and an attempt on identification of telomerase reverse transcriptase (PmTERT) were made. Telomeric repeat amplification protocol revealed that telomerase-dependent telomeric lengthening has been taking place in P. monodon and the adult tissues were retaining this capacity throughout their lifespan with the highest activity in ovary, testis and lymphoid organ. However, telomerase activity could not be detected in lymphoid cells in culture. The canonical telomeric repeats added by telomerase of lymphoid tissue extract were identified as TTAGG, but pentameric repeats GGTTA and AGGTT were also added by the telomerase. PmTERT protein sequence (partial) shared 100 % identity with the TERT sequence of Daphnia pulex, 27 % sequence identity with Purple sea urchin and 24-25 % with Zebra fish. Undetectable telomerase activity in lymphoid cell culture supports the hypothesis that the inadequate telomerase activity or gene expression may be a reason that prevents neoplastic transformation and spontaneous immortalization of the cells in vitro. Thus, it is envisaged that telomerase activation in lymphoid cells may surmount cellular ageing for in vitro transformation and cell line establishment. PMID:26084784

  16. Clonal cell populations unresponsive to radiosensitization induced by telomerase inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Ju, Yeun-Jin; Shin, Hyun-Jin; Park, Jeong-Eun; Juhn, Kyoung-Mi; Woo, Seon Rang; Kim, Hee-Young; Han, Young-Hoon; Hwang, Sang-Gu; Hong, Sung-Hee; Kang, Chang-Mo [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of); Yoo, Young-Do [Laboratory of Molecular Cell Biology, Graduate School of Medicine, Korea University College of Medicine, Korea University, Seoul 136-705 (Korea, Republic of); Park, Won-Bong [Division of Natural Science, Seoul Women' s University, Seoul 139-774 (Korea, Republic of); Cho, Myung-Haing [Laboratory of Toxicology, College of Veterinary Medicine, Seoul National University, Seoul (Korea, Republic of); Park, Gil Hong, E-mail: ghpark@korea.ac.kr [Department of Biochemistry, College of Medicine, Korea University, Seoul (Korea, Republic of); Lee, Kee-Ho, E-mail: khlee@kirams.re.kr [Division of Radiation Cancer Research, Korea Institute of Radiological and Medical Sciences, Seoul 139-706 (Korea, Republic of)

    2010-11-12

    Research highlights: {yields} In our present manuscript, we have clearly showed an interesting but problematic obstacle of a radiosensitization strategy based on telomerase inhibition by showing that: Clonal population unresponsive to this radiosensitization occasionally arise. {yields} The telomere length of unsensitized clones was reduced, as was that of most sensitized clones. {yields} The unsensitized clones did not show chromosome end fusion which was noted in all sensitized clones. {yields} P53 status is not associated with the occurrence of unsensitized clone. {yields} Telomere end capping in unsensitized clone is operative even under telomerase deficiency. -- Abstract: A combination of a radiotherapeutic regimen with telomerase inhibition is valuable when tumor cells are to be sensitized to radiation. Here, we describe cell clones unresponsive to radiosensitization after telomere shortening. After extensive division of individual transformed clones of mTERC{sup -/-} cells, about 22% of clones were unresponsive to radiosensitization even though telomerase action was inhibited. The telomere lengths of unsensitized mTERC{sup -/-} clones were reduced, as were those of most sensitized clones. However, the unsensitized clones did not exhibit chromosomal end-to-end fusion to the extent noted in all sensitized clones. Thus, a defense mechanism preventing telomere erosion is operative even when telomeres become shorter under conditions of telomerase deficiency, and results in unresponsiveness to the radiosensitization generally mediated by telomere shortening.

  17. Clonal cell populations unresponsive to radiosensitization induced by telomerase inhibition

    International Nuclear Information System (INIS)

    Research highlights: → In our present manuscript, we have clearly showed an interesting but problematic obstacle of a radiosensitization strategy based on telomerase inhibition by showing that: Clonal population unresponsive to this radiosensitization occasionally arise. → The telomere length of unsensitized clones was reduced, as was that of most sensitized clones. → The unsensitized clones did not show chromosome end fusion which was noted in all sensitized clones. → P53 status is not associated with the occurrence of unsensitized clone. → Telomere end capping in unsensitized clone is operative even under telomerase deficiency. -- Abstract: A combination of a radiotherapeutic regimen with telomerase inhibition is valuable when tumor cells are to be sensitized to radiation. Here, we describe cell clones unresponsive to radiosensitization after telomere shortening. After extensive division of individual transformed clones of mTERC-/- cells, about 22% of clones were unresponsive to radiosensitization even though telomerase action was inhibited. The telomere lengths of unsensitized mTERC-/- clones were reduced, as were those of most sensitized clones. However, the unsensitized clones did not exhibit chromosomal end-to-end fusion to the extent noted in all sensitized clones. Thus, a defense mechanism preventing telomere erosion is operative even when telomeres become shorter under conditions of telomerase deficiency, and results in unresponsiveness to the radiosensitization generally mediated by telomere shortening.

  18. PCR-free and label-free fluorescent detection of telomerase activity at single-cell level based on triple amplification.

    Science.gov (United States)

    Gao, Yanfang; Xu, Jing; Li, Baoxin; Jin, Yan

    2016-07-15

    As a universal biomarker for cancer diagnostics and cancer therapeutics, telomerase has attracted extensive attention concerning its detection and discovery of its inhibitors. Herein, we developed a PCR-free and label-free fluorescent strategy for facile, reliable and highly sensitive assay of human telomerase activity from crude cancer cell extracts. A G-quadruplex-selective fluorescent dye, N-methyl mesoporphyrin IX (NMM), was utilized as signal probe. Two hairpin probes with hidden G-quadruplex strand in their stem were designed as assembly components of strand displacement reaction (SDR). In this strategy, one telomerase elongation product contains several hexamer repeats which can hybridize with numerous assistant DNA to release a lot of trigger DNA (T-DNA) of SDR for achieving first step amplification. Then, strand displacement reaction led to the formation of G-quadruplex at the both end of two hairpin DNA probes for realizing second step amplification. Finally, the re-released T-DNA initiated another cycle of SDR, resulting in a significant increase in the fluorescence intensity of NMM. By taking advantage of triple signal amplification, the telomerase activity in the HeLa extracts equivalent to 1-3000 cells was detected in homogeneous solution. Telomerase activities of different cell lines, including cancer cells and normal cell, were also successfully evaluated. Meanwhile, the inhibition effect of 3'-azido-3'-deoxythymidine (AZT) was also investigated. Therefore, it offers a simple and reliable method for detecting telomerase activity at single-cell level without complex pre-modification of probe and enzyme auxiliary signal amplification, which has the merits of simplicity, rapid response, low cost and high reliability. PMID:26999622

  19. Evidence for ovarian granulosa stem cells: telomerase activity and localization of the telomerase ribonucleic acid component in bovine ovarian follicles.

    Science.gov (United States)

    Lavranos, T C; Mathis, J M; Latham, S E; Kalionis, B; Shay, J W; Rodgers, R J

    1999-08-01

    We have previously postulated that granulosa cells of developing follicles arise from a population of stem cells. Stem cells and cancer cells can divide indefinitely partly because they express telomerase. Telomerase is a ribonucleoprotein enzyme that repairs the ends of telomeres that otherwise shorten progressively upon each successive cell division. In this study we carried out cell cycle analyses and examined telomerase expression to examine our hypothesis. Preantral (60-100 microm) and small (1 mm) follicles, as well as granulosa cells from medium-sized (3 mm) and large (6-8 mm) follicles, were isolated. Cell cycle analyses and expression of Ki-67, a cell cycle-related protein, were undertaken on follicles of each size (n = 3) by flow cytometry; 12% to 16% of granulosa cells in all follicles were in the S phase, and less than 2% were in the G(2)/M phase. Telomerase activity (n = 3) was highest in the small preantral follicles, declining at the 1-mm stage and even further at the 3-mm stage. In situ hybridization histochemistry was carried out on bovine ovaries, and telomerase RNA was detected in the granulosa cells of growing follicles but not primordial follicles. Two major patterns of staining were observed in the membrana granulosa of antral follicles: staining in the middle and antral layers, and staining in the middle and basal layers. No staining was detected in oocytes. Our results strongly support our hypothesis that granulosa cells arise from a population of stem cells. PMID:10411512

  20. Telomere and telomerase as targets for anti-cancer and regeneration therapies

    Institute of Scientific and Technical Information of China (English)

    Yi-hsin HSU; Jing-jer LIN

    2005-01-01

    Telomerase is a ribonucleoprotein that directs the synthesis of telomeric sequence.It is detected in majority of malignant tumors, but not in most normal somatic cells.Because telomerase plays a critical role in cell immortality and tumor formation, it has been one of the targets for anti-cancer and regeneration drug development. In this review, we will discuss therapeutic approaches based mainly on small molecules that have been developed to inhibit telomerase activity, modulate telomerase expression, and telomerase directed gene therapy.

  1. Telomeres and telomerase as therapeutic targets to prevent and treat age-related diseases [version 1; referees: 4 approved

    Directory of Open Access Journals (Sweden)

    Christian Bär

    2016-01-01

    Full Text Available Telomeres, the protective ends of linear chromosomes, shorten throughout an individual’s lifetime. Telomere shortening is a hallmark of molecular aging and is associated with premature appearance of diseases associated with aging. Here, we discuss the role of telomere shortening as a direct cause for aging and age-related diseases. In particular, we draw attention to the fact that telomere length influences longevity. Furthermore, we discuss intrinsic and environmental factors that can impact on human telomere erosion. Finally, we highlight recent advances in telomerase-based therapeutic strategies for the treatment of diseases associated with extremely short telomeres owing to mutations in telomerase, as well as age-related diseases, and ultimately aging itself.

  2. Combination treatment with flavonoid morin and telomerase inhibitor MST‑312 reduces cancer stem cell traits by targeting STAT3 and telomerase.

    Science.gov (United States)

    Chung, Seyung S; Oliva, Bryant; Dwabe, Sami; Vadgama, Jaydutt V

    2016-08-01

    Colorectal cancer (CRC) is one of the most commonly diagnosed cancers worldwide. The malignant CRC that undergoes metastasis in the advanced stage is usually refractory to existing chemotherapy and shows a poor prognosis. However, to date, efficient targeted-therapy for metastatic CRC is ill-defined. We tested the hypothesis that combined treatment of flavonoid morin and telomerase inhibitor MST‑312 may reduce the cancer stem cell (CSC) traits. To characterize CSC phenotype, we performed the CD133/CD44 subpopulation profiling, tumorsphere formation assay, cell invasion assay and wound healing assay. We have examined the augmenting effects of the combined treatment of morin and MST‑312 for 5-FU (5-fluorouracil) efficacy in human colorectal cancer. Morin and MST‑312 combined treatment reduced CD133 (+) and CD44 (+) subpopulations in human colorectal and breast cancer cells, respectively. Tumorsphere formation and cell invasiveness were decreased with the morin and MST‑312 combination treatment. Consistent with these data, morin and MST‑312 treatment decreased the wound healing capacity of human breast cancer cells. Stress and apoptosis antibody arrays revealed that there were specific upregulated and downregulated proteins resulting from different treatments. Phosphorylation levels of BAD, p53 and Chk1 were enhanced upon morin/MST‑312 treatments in HT-29 cells, whereas caspase-3 cleavage level and expression of IκBα were downregulated by combined morin/MST‑312 treatment in SW620 cells. Finally, morin and MST‑312 co-treatment further augmented the 5-FU efficacy, chemosensitizing the 5-FU resistant human colorectal cancer cells. Taken together, our study suggests that novel targeted-therapy can be implemented by using flavonoid morin and telomerase inhibitor MST‑312 for improved cancer prognosis. PMID:27279256

  3. Telomerase-Independent Paths to Immortality in Predictable Cancer Subtypes

    Directory of Open Access Journals (Sweden)

    Stephen T Durant

    2012-01-01

    Full Text Available The vast majority of cancers commandeer the activity of telomerase - the remarkable enzyme responsible for prolonging cellular lifespan by maintaining the length of telomeres at the ends of chromosomes. Telomerase is only normally active in embryonic and highly proliferative somatic cells. Thus, targeting telomerase is an attractive anti-cancer therapeutic rationale currently under investigation in various phases of clinical development. However, previous reports suggest that an average of 10-15% of all cancers lose the functional activity of telomerase and most of these turn to an Alternative Lengthening of Telomeres pathway (ALT. ALT-positive tumours will therefore not respond to anti-telomerase therapies and there is a real possibility that such drugs would be toxic to normal telomerase-utilising cells and ultimately select for resistant cells that activate an ALT mechanism. ALT exploits certain DNA damage response (DDR components to counteract telomere shortening and rapid trimming. ALT has been reported in many cancer subtypes including sarcoma, gastric carcinoma, central nervous system malignancies, subtypes of kidney (Wilm's Tumour and bladder carcinoma, mesothelioma, malignant melanoma and germ cell testicular cancers to name but a few. A recent heroic study that analysed ALT in over six thousand tumour samples supports this historical spread, although only reporting an approximate 4% prevalence. This review highlights the various methods of ALT detection, unravels several molecular ALT models thought to promote telomere maintenance and elongation, spotlights the DDR components known to facilitate these and explores why certain tissues are more likely to subvert DDR away from its usually protective functions, resulting in a predictive pattern of prevalence in specific cancer subsets.

  4. Herpesvirus telomerase RNA(vTR)-dependent lymphoma formation does not require interaction of vTR with telomerase reverse transcriptase (TERT)

    OpenAIRE

    Kaufer, Benedikt B; Sascha Trapp; Jarosinski, Keith W.; Nikolaus Osterrieder

    2010-01-01

    Telomerase is a ribonucleoprotein complex involved in the maintenance of telomeres, a protective structure at the distal ends of chromosomes. The enzyme complex contains two main components, telomerase reverse transcriptase (TERT), the catalytic subunit, and telomerase RNA (TR), which serves as a template for the addition of telomeric repeats (TTAGGG)(n). Marek's disease virus (MDV), an oncogenic herpesvirus inducing fatal lymphoma in chickens, encodes a TR homologue, viral TR (vTR), which si...

  5. High telomerase activity and long telomeres in advanced hepatocellular carcinomas with poor prognosis.

    Science.gov (United States)

    Oh, Bong-Kyeong; Kim, Haeryoung; Park, Young Nyun; Yoo, Jeong Eun; Choi, Jinsub; Kim, Kyung-Sik; Lee, Jae Jung; Park, Chanil

    2008-02-01

    Telomerase reactivation and telomere maintenance are crucial in carcinogenesis and tumor progression. In this study, the relationships between telomere parameters, chromosomal instability and clinicopathological features were evaluated in hepatocellular carcinomas (HCCs). Telomere length (TL), telomerase activity (TA) and human telomerase reverse transcriptase (hTERT) mRNA levels were measured in 49 hepatitis B virus (HBV)-related HCCs and corresponding non-tumorous tissues. The results were compared with clinicopathological data, including differentiation, multipolar mitosis (MM), anaphase bridge, immunohistochemical stain results for cytokeratin 19 (CK19) and patient outcome. TL of HCCs ranged from 4.7 to 13.1 kb, and 44.4% of HCCs showed telomere lengthening. hTERT mRNA levels and TA were closely related (P=0.008), and were significantly higher in HCCs than non-tumorous tissues. TL was significantly higher in HCCs with strong TA (P=0.048), high hTERT mRNA levels (P=0.001) and poor differentiation (P=0.041). Frequent MM was associated with poor differentiation (P=0.007) and advanced stage (Ptelomeres than CK19- HCCs (P=0.046). Overall survival was poor in HCCs with MM >0.4 per field (P=0.016), high TA (P=0.009) and high TL ratio (HCC/non-HCC) >0.8 (P=0.044). Our results show that long telomeres, high TA and high mitotic instability are poor prognostic markers for HBV-related HCCs and their close association suggests that telomere maintenance may be important for the progression of HCCs with high chromosomal instability to more aggressive ones. PMID:18158557

  6. Coupling a DNA-Based Machine with Glucometer Readouts for Amplified Detection of Telomerase Activity in Cancer Cells

    OpenAIRE

    Wenjing Wang; Shan Huang; Jingjing Li; Kai Rui; Jian-Rong Zhang; Jun-Jie Zhu

    2016-01-01

    The strong correlation between cancer and telomerase activity has inspired the development of new strategies to evaluate telomerase activity. Here, a personal glucose meter (PGM) system that uses DNA-based machine amplification to detect telomerase in cancer cells is reported. In this assay, telomerase elongation products are amplified in the form of another type of product by a DNA-based machine. This process can only be activated by the hybridization of the extended telomerase substrate (TS...

  7. Detection of telomerase activity in psoriasis lesional skin and correlation with Ki-67 expression and suppression by retinoic acid.

    OpenAIRE

    Jang, H S; OH, C. K.; Jo, J. H.; Kim, Y.S.; Kwon, K. S.

    2001-01-01

    Telomerase activity is usually detected in most tumor tissues but not in normal tissues. Recently, there is increasing evidence that telomerase activity is associated with cell proliferation without malignancy, whereas there is little information about telomerase activity and its relationship with cell proliferation in chronic hyperproliferative skin diseases. Thus, we studied telomerase activity in skins from 10 patients with psoriasis and compared telomerase activity with the expression of ...

  8. Telomerase in pulmonary fibrosis. A link to alveolar cell apoptosis and differentiation

    Directory of Open Access Journals (Sweden)

    Argyris Tzouvelekis

    2010-01-01

    Full Text Available SUMMARY. Introduction: Telomerase is crucial for extended life span and differentiation and is linked to immortality. Therefore, its role may be crucial in the pathogenesis of pulmonary fibrosis. Our objective was to implicate telomerase in the pathogenesis of idiopathic fibrotic lung disease. Patients and Methods: Assessment of telomerase activity and expression was carried out using TRAP detection kit and qRT-PCR. Experimental procedure was enhanced by a series of immunostainings and fluorescence in situ hybridization analysis in tissue microarrays constructed with tissue samples from patients with idiopathic pulmonary fibrosis (IPF and cryptogenic organizing pneumonia (COP. Results: We demonstrated significant downregulation of telomerase expression and activity in patients with fibrotic lung disease compared to controls. Immunolocalization studies coupled by FISH analysis revealed the presence of two subpopulations of type II AECs based on their telomerase expression levels: telomerase positive type II AECs, mainly overlying areas of active fibrosis and telomerase negative type II AECs, mainly localized in areas of established fibrosis. Conclusions: Downregulation of telomerase expression and activity in IPF may indicate a causal relationship between low telomerase expression and disease pathogenesis. The duality phenomenon in telomerase expression suggests that telomerase may regulate the fate of AECs towards either an apoptotic or a mesenchymal phenotype contributing directly to fibrosis. Pneumon 2010, 23(3:207-239.

  9. Absence of Radio-Sensitization mediated by Telomerase-inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hee Young; Ju, Yeun Jin; Park, Jeong Eun [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)] (and others)

    2009-05-15

    The radio-therapeutics's problem in tumor is the repeated return of radio-resistant tumor cells during radiotherapy. Therefore, many studies have been accomplished to develop many modulators regulating this mechanism. Besides, sensitizing agents have actively been exploited to enhance the radio-therapeutic efficacy for cancer. The combination anticancer radiotherapeutic cure with telomerase inhibition is useful to sensitize tumor cells to radiation, depending on telomere dysfunction and eventual genomic instability. In our studies, we showed that there was absence of radio-sensitization mediated by telomerase deficiency in clonal cell population.

  10. Two pathways recruit telomerase to Saccharomyces cerevisiae telomeres.

    Directory of Open Access Journals (Sweden)

    Angela Chan

    2008-10-01

    Full Text Available The catalytic subunit of yeast telomerase, Est2p, is a telomere associated throughout most of the cell cycle, while the Est1p subunit binds only in late S/G2 phase, the time of telomerase action. Est2p binding in G1/early S phase requires a specific interaction between telomerase RNA (TLC1 and Ku80p. Here, we show that in four telomerase-deficient strains (cdc13-2, est1A, tlc1-SD, and tlc1-BD, Est2p telomere binding was normal in G1/early S phase but reduced to about 40-50% of wild type levels in late S/G2 phase. Est1p telomere association was low in all four strains. Wild type levels of Est2p telomere binding in late S/G2 phase was Est1p-dependent and required that Est1p be both telomere-bound and associated with a stem-bulge region in TLC1 RNA. In three telomerase-deficient strains in which Est1p is not Est2p-associated (tlc1-SD, tlc1-BD, and est2A, Est1p was present at normal levels but its telomere binding was very low. When the G1/early S phase and the late S/G2 phase telomerase recruitment pathways were both disrupted, neither Est2p nor Est1p was telomere-associated. We conclude that reduced levels of Est2p and low Est1p telomere binding in late S/G2 phase correlated with an est phenotype, while a WT level of Est2p binding in G1 was not sufficient to maintain telomeres. In addition, even though Cdc13p and Est1p interact by two hybrid, biochemical and genetic criteria, this interaction did not occur unless Est1p was Est2p-associated, suggesting that Est1p comes to the telomere only as part of the holoenzyme. Finally, the G1 and late S/G2 phase pathways for telomerase recruitment are distinct and are likely the only ones that bring telomerase to telomeres in wild-type cells.

  11. Label-Free Detection of Telomerase Activity in Urine Using Telomerase-Responsive Porous Anodic Alumina Nanochannels.

    Science.gov (United States)

    Liu, Xu; Wei, Min; Liu, Yuanjian; Lv, Bingjing; Wei, Wei; Zhang, Yuanjian; Liu, Songqin

    2016-08-16

    Telomerase is closely related to cancers, which makes it one of the most widely known tumor marker. Recently, many methods have been reported for telomerase activity measurement in which complex label procedures were commonly used. In this paper, a label-free method for detection of telomerase activity in urine based on steric hindrance changes induced by confinement geometry in the porous anodic alumina (PAA) nanochannels was proposed. Telomerase substrate (TS) primer was first assembled on the inside wall of PAA nanochannels by Schiff reaction under mild conditions. Then, under the action of telomerase, TS primer was amplified and extended to repeating G-rich sequences (TTAGGG)x, which formed multiplex G-quadruplex in the presence of potassium ions (K(+)). This configurational change led to the increment of steric hindrance in the nanochannels, resulting in the decrement of anodic current of potassium ferricyanide (K3[Fe(CN)6]). Compared with previously reported methods based on PAA nanochannels (usually one G-quadruplex formed), multiplex repeating G-quadruplex formed on one TS primer in this work. As a result, large current drop (∼3.6 μA, 36%) was obtained, which gave facility to improve the detection sensitivity. The decreased ratio of anodic current has a linear correlation with the logarithm of HeLa cell number in the range of 10-5000 cells, with the detection limit of seven cells. The method is simple, reliable, and has been successfully applied in the detection of telomerase in urine with good accuracy, selectivity and reproducibility. In addition, the method is nondestructive test compared to blood analysis and pathology tests, which is significant for cancer discovery, development, and prognosis. PMID:27420905

  12. Inhibition of telomerase by G-quartet DMA structures

    Science.gov (United States)

    Zahler, Alan M.; Williamson, James R.; Cech, Thomas R.; Prescott, David M.

    1991-04-01

    THE ends or telomeres of the linear chromosomes of eukaryotes are composed of tandem repeats of short DNA sequences, one strand being rich in guanine (G strand) and the complementary strand in cytosine1,2. Telomere synthesis involves the addition of telomeric repeats to the G strand by telomere terminal transferase (telomerase)3-6. Telomeric G-strand DNAs from a variety of organisms adopt compact structures7, the most stable of which is explained by the formation of G-quartets8,9. Here we investigate the capacity of the different folded forms of telomeric DNA to serve as primers for the Oxytricha nova telomerase in vitro. Formation of the K+-stabilized G-quartet structure in a primer inhibits its use by telomerase. Furthermore, the octanucleotide T4G4, which does not fold, is a better primer than (T4G4)2, which can form a foldback structure7-10. We conclude that telomerase does not require any folding of its DNA primer. Folding of telomeric DNA into G-quartet structures seems to influence the extent of telomere elongation in vitro and might therefore act as a negative regulator of elongation in vivo.

  13. Urine Telomerase for Diagnosis and Surveillance of Bladder Cancer

    Directory of Open Access Journals (Sweden)

    Angela Lamarca

    2012-01-01

    Full Text Available Bladder cancer has increased incidence during last decades. For those patients with nonmuscle involved tumors, noninvasive diagnosis test and surveillance methods must be designed to avoid current cystoscopies that nowadays are done regularly in a lot of patients. Novel urine biomarkers have been developed during last years. Telomerase is important in cancer biology, improving the division capacity of cancer cells. Even urinary telomerase could be a potentially useful urinary tumor marker; its use for diagnosis of asymptomatic and symptomatic patients or its impact during surveillance is still unknown. Moreover, there will need to be uniformity and standardization in the assays before it can become useful in clinical practice. It does not seem to exist a real difference between the most classical assays for the detection of urine telomerase (TRAP and hTERT. However, the new detection methods with modified TeloTAGGG telomerase or with gold nanoparticles must also be taken into consideration for the correct development of this diagnosis method. Maybe the target population would be the high-risk groups within screening programs. To date there is no enough evidence to use it alone and to eliminate cystoscopies from the diagnosis and surveillance of these patients. The combination with cytology or FISH is still preferred.

  14. Telomerase-null survivor screening identifies novel telomere recombination regulators.

    Directory of Open Access Journals (Sweden)

    Yan Hu

    Full Text Available Telomeres are protein-DNA structures found at the ends of linear chromosomes and are crucial for genome integrity. Telomeric DNA length is primarily maintained by the enzyme telomerase. Cells lacking telomerase will undergo senescence when telomeres become critically short. In Saccharomyces cerevisiae, a very small percentage of cells lacking telomerase can remain viable by lengthening telomeres via two distinct homologous recombination pathways. These "survivor" cells are classified as either Type I or Type II, with each class of survivor possessing distinct telomeric DNA structures and genetic requirements. To elucidate the regulatory pathways contributing to survivor generation, we knocked out the telomerase RNA gene TLC1 in 280 telomere-length-maintenance (TLM gene mutants and examined telomere structures in post-senescent survivors. We uncovered new functional roles for 10 genes that affect the emerging ratio of Type I versus Type II survivors and 22 genes that are required for Type II survivor generation. We further verified that Pif1 helicase was required for Type I recombination and that the INO80 chromatin remodeling complex greatly affected the emerging frequency of Type I survivors. Finally, we found the Rad6-mediated ubiquitination pathway and the KEOPS complex were required for Type II recombination. Our data provide an independent line of evidence supporting the idea that these genes play important roles in telomere dynamics.

  15. TRAPping telomerase within the intestinal stem cell niche

    OpenAIRE

    Pech, Matthew F.; Artandi, Steven E.

    2011-01-01

    Recent work from Hans Clevers' lab reveals high telomerase activity and telomere length in dividing LGR5-positive intestinal stem cells. They further report random chromosome segregation and thus challenge the ‘immortal strand' hypothesis at least for this stem cell population.

  16. TPP1 is a homologue of ciliate TEBP-β and interacts with POT1 to recruit telomerase

    Science.gov (United States)

    Xin, Huawei; Liu, Dan; Wan, Ma; Safari, Amin; Kim, Hyeung; Sun, Wen; O'Connor, Matthew S.; Songyang, Zhou

    2007-02-01

    Telomere dysfunction may result in chromosomal abnormalities, DNA damage responses, and even cancer. Early studies in lower organisms have helped to establish the crucial role of telomerase and telomeric proteins in maintaining telomere length and protecting telomere ends. In Oxytricha nova, telomere G-overhangs are protected by the TEBP-α/β heterodimer. Human telomeres contain duplex telomeric repeats with 3' single-stranded G-overhangs, and may fold into a t-loop structure that helps to shield them from being recognized as DNA breaks. Additionally, the TEBP-α homologue, POT1, which binds telomeric single-stranded DNA (ssDNA), associates with multiple telomeric proteins (for example, TPP1, TIN2, TRF1, TRF2 and RAP1) to form the six-protein telosome/shelterin and other subcomplexes. These telomeric protein complexes in turn interact with diverse pathways to form the telomere interactome for telomere maintenance. However, the mechanisms by which the POT1-containing telosome communicates with telomerase to regulate telomeres remain to be elucidated. Here we demonstrate that TPP1 is a putative mammalian homologue of TEBP-β and contains a predicted amino-terminal oligonucleotide/oligosaccharide binding (OB) fold. TPP1-POT1 association enhanced POT1 affinity for telomeric ssDNA. In addition, the TPP1 OB fold, as well as POT1-TPP1 binding, seemed critical for POT1-mediated telomere-length control and telomere-end protection in human cells. Disruption of POT1-TPP1 interaction by dominant negative TPP1 expression or RNA interference (RNAi) resulted in telomere-length alteration and DNA damage responses. Furthermore, we offer evidence that TPP1 associates with the telomerase in a TPP1-OB-fold-dependent manner, providing a physical link between telomerase and the telosome/shelterin complex. Our findings highlight the critical role of TPP1 in telomere maintenance, and support a yin-yang model in which TPP1 and POT1 function as a unit to protect human telomeres, by both

  17. Clinical significance of telomerase and its associate genes expression in the maintenance of telomere length in squamous cell carcinoma of the esophagus

    Institute of Scientific and Technical Information of China (English)

    Chung-Ping Hsu; Li-Wen Lee; Sen-Ei Shai; Chih-Yi Chen

    2005-01-01

    AIM: To observe the interaction between the expression of telomerase activity (TA) and its associate genes in regulation of the terminal restriction fragment length(TRFL) in esophageal squamous cell carcinoma (SCC).METHODS: Seventy-four specimens of esophageal SCC were examined. The TA was measured by telomeric repeat amplification protocol (TRAP) assay, and the associated genes [human telomerase-specific reverse transcriptase (hTERT), hTERC, TP1, c-Myc, TRF1,and TRF2] were detected using RT-PCR method. The TRFL was measured by Telomere Length Assay Kit and Southern blotting. The correlations between the expression of telomerase and its associated genes with the TRFL and survivals were examined.RESULTS: Expressions of the TA, hTERT, hTERC, TP1,c-Myc, TRF1, and TRF2 genes were observed in 85.1%,64.9%, 79.7%, 100.0%, 94.6%, 82.4%, and 91.9% of the tumor tissues, respectively. The TRFL of the tumor and normal esophageal tissues were 2.70±1.42 and 4.93±1.74 kb, respectively (P<0.0001). The TRFL of the telomerase positive and telomerase negative tumor tissues were 2.72±1.44 and 2.58±1.32 kb, respectively (P = 0.767).The TRFL ratios (TRFLR) of the telomerase positive and telomerase negative tumor tissues were 0.55±0.22 and 0.59±0.41, respectively (P = 0.742). The expression rates of h-TERT (P = 0.0002), hTERC (P<0.0001), and TRF1(P = 0.002) in the tumor tissues are higher than those of the normal paired tissues. Though TA is markedly activated in tumor tissues (P<0.0001), its expression is not related to clinicopathological parameters including gender, tumor differentiation, and TNM stages. The cumulative 4-year survival rates of telomerase positive and telomerase negative cases were 35.86% and 31.2%,respectively (P = 0.8442). The cumulative 4-year survival rates of patients with their TRFLR ≤85% and >85%were 38.7% and 15.7%, respectively (P = 0.1307).CONCLUSION: Though telomerase expression is not related to tumor stages and prognosis, our data support

  18. Heparan Sulfate Proteoglycans Promote Telomerase Internalization and MHC Class II Presentation on Dendritic Cells.

    Science.gov (United States)

    Galaine, Jeanne; Kellermann, Guillaume; Guillaume, Yves; Boidot, Romain; Picard, Emilie; Loyon, Romain; Queiroz, Lise; Boullerot, Laura; Beziaud, Laurent; Jary, Marine; Mansi, Laura; André, Claire; Lethier, Lydie; Ségal-Bendirdjian, Evelyne; Borg, Christophe; Godet, Yann; Adotévi, Olivier

    2016-09-01

    Telomerase is a prototype-shared tumor Ag and represents an attractive target for anticancer immunotherapy. We have previously described promiscuous and immunogenic HLA-DR-restricted peptides derived from human telomerase reverse transcriptase (hTERT) and referred as universal cancer peptide (UCP). In nonsmall cell lung cancer, the presence of spontaneous UCP-specific CD4 T cell responses increases the survival of chemotherapy-responding patients. However, the precise mechanisms of hTERT's uptake, processing, and presentation on MHC-II molecules to stimulate CD4 T cells are poorly understood. In this work, by using well-characterized UCP-specific CD4 T cell clones, we showed that hTERT processing and presentation on MHC-II involve both classical endolysosomal and nonclassical cytosolic pathways. Furthermore, to our knowledge, we demonstrated for the first time that hTERT's internalization by dendritic cells requires its interaction with surface heparan sulfate proteoglycans. Altogether, our findings provide a novel mechanism of tumor-specific CD4 T cell activation and will be useful for the development of novel cancer immunotherapies that harness CD4 T cells. PMID:27481844

  19. Immortalization of pig fibroblast cells by transposon-mediated ectopic expression of porcine telomerase reverse transcriptase.

    Science.gov (United States)

    He, Shan; Li, Yangyang; Chen, Yang; Zhu, Yue; Zhang, Xinyu; Xia, Xiaoli; Sun, Huaichang

    2016-08-01

    Pigs are the most economically important livestock, but pig cell lines useful for physiological studies and/or vaccine development are limited. Although several pig cell lines have been generated by oncogene transformation or human telomerase reverse transcriptase (TERT) immortalization, these cell lines contain viral sequences and/or antibiotic resistance genes. In this study, we established a new method for generating pig cell lines using the Sleeping Beauty (SB) transposon-mediated ectopic expression of porcine telomerase reverse transcriptase (pTERT). The performance of the new method was confirmed by generating a pig fibroblast cell (PFC) line. After transfection of primary PFCs with the SB transposon system, one cell clone containing the pTERT expression cassette was selected by dilution cloning and passed for different generations. After passage for more than 40 generations, the cell line retained stable expression of ectopic pTERT and continuous growth potential. Further characterization showed that the cell line kept the fibroblast morphology, growth curve, population doubling time, cloning efficiency, marker gene expression pattern, cell cycle distribution and anchorage-dependent growth property of the primary cells. These data suggest that the new method established is useful for generating pig cell lines without viral sequence and antibiotic resistant gene. PMID:26341227

  20. The AAA-ATPase NVL2 is a telomerase component essential for holoenzyme assembly

    Energy Technology Data Exchange (ETDEWEB)

    Her, Joonyoung [Departments of Biology and Integrated Omics for Biomedical Science, Yonsei University, Seoul 120-749 (Korea, Republic of); Chung, In Kwon, E-mail: topoviro@yonsei.ac.kr [Departments of Biology and Integrated Omics for Biomedical Science, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2012-01-20

    Highlights: Black-Right-Pointing-Pointer Identification of the AAA-ATPase NVL2 as a novel hTERT-interacting protein. Black-Right-Pointing-Pointer NVL2 associates with catalytically active telomerase via an interaction with hTERT. Black-Right-Pointing-Pointer NVL2 is a telomerase component essential for holoenzyme assembly. Black-Right-Pointing-Pointer ATP-binding activity of NVL2 is required for hTERT binding and telomerase assembly. -- Abstract: Continued cell proliferation requires telomerase to maintain functional telomeres that are essential for chromosome integrity. Although the core enzyme includes a telomerase reverse transcriptase (TERT) and a telomerase RNA component (TERC), a number of auxiliary proteins have been identified to regulate telomerase assembly, localization, and enzymatic activity. Here we describe the characterization of the AAA-ATPase NVL2 as a novel hTERT-interacting protein. NVL2 interacts and co-localizes with hTERT in the nucleolus. NLV2 is also found in association with catalytically competent telomerase in cell lysates through an interaction with hTERT. Depletion of endogenous NVL2 by small interfering RNA led to a decrease in hTERT without affecting the steady-state levels of hTERT mRNA, thereby reducing telomerase activity, suggesting that NVL2 is an essential component of the telomerase holoenzyme. We also found that ATP-binding activity of NVL2 is required for hTERT binding as well as telomerase assembly. Our findings suggest that NVL2, in addition to its role in ribosome biosynthesis, is essential for telomerase biogenesis and provides an alternative approach for inhibiting telomerase activity in cancer.

  1. P. berghei telomerase subunit TERT is essential for parasite survival.

    Directory of Open Access Journals (Sweden)

    Agnieszka A Religa

    Full Text Available Telomeres define the ends of chromosomes protecting eukaryotic cells from chromosome instability and eventual cell death. The complex regulation of telomeres involves various proteins including telomerase, which is a specialized ribonucleoprotein responsible for telomere maintenance. Telomeres of chromosomes of malaria parasites are kept at a constant length during blood stage proliferation. The 7-bp telomere repeat sequence is universal across different Plasmodium species (GGGTTT/CA, though the average telomere length varies. The catalytic subunit of telomerase, telomerase reverse transcriptase (TERT, is present in all sequenced Plasmodium species and is approximately three times larger than other eukaryotic TERTs. The Plasmodium RNA component of TERT has recently been identified in silico. A strategy to delete the gene encoding TERT via double cross-over (DXO homologous recombination was undertaken to study the telomerase function in P. berghei. Expression of both TERT and the RNA component (TR in P. berghei blood stages was analysed by Western blotting and Northern analysis. Average telomere length was measured in several Plasmodium species using Telomere Restriction Fragment (TRF analysis. TERT and TR were detected in blood stages and an average telomere length of ∼ 950 bp established. Deletion of the tert gene was performed using standard transfection methodologies and we show the presence of tert- mutants in the transfected parasite populations. Cloning of tert- mutants has been attempted multiple times without success. Thorough analysis of the transfected parasite populations and the parasite obtained from extensive parasite cloning from these populations provide evidence for a so called delayed death phenotype as observed in different organisms lacking TERT. The findings indicate that TERT is essential for P. berghei cell survival. The study extends our current knowledge on telomere biology in malaria parasites and validates further

  2. A Telomerase-Specific Doxorubicin-Releasing Molecular Beacon for Cancer Theranostics.

    Science.gov (United States)

    Ma, Yi; Wang, Zhaohui; Zhang, Min; Han, Zhihao; Chen, Dan; Zhu, Qiuyun; Gao, Weidong; Qian, Zhiyu; Gu, Yueqing

    2016-03-01

    A molecular beacon-based drug delivery system was designed for both detection of telomerase activity in living cells and telomerase-triggered drug release for precise cancer treatment. This system is composed of a gold nanoparticle core densely packed with FITC-labeled hairpin DNA sequences hybridized with telomerase primers. Molecules of the anticancer drug doxorubicin were intercalated into the stem region of the DNA sequence. The presence of telomerase will elongate the primers, leading to inner chain substitution followed by the release of the FITC fluorescence and the trapped doxorubicin. This molecular beacon could specifically distinguish tumor cells and normal cells based on telomerase activity, precisely release doxorubicin in response to telomerase activity in the tumor cells, and prevent toxicity to normal organs. PMID:26848056

  3. INHIBITION OF TELOMERASE ACTIVITY DURING INDUCTION OF HL-60 CELLS BY RETINOID Ro13-7410

    Institute of Scientific and Technical Information of China (English)

    LIU Xiao-shan; LOU Ling-sheng; JIANG Ji-kai; LIU Bei-zhong; ZHOU Jian-fang; TANG Zong-shan; LI Xue-xian; KANG Ge-fei

    1999-01-01

    Objective: To investigate the effects of Ro13-7410on telomerase activity and cell cycle distribution.Methods: Telomerase activity of HL-60 cells induced by retinoid Ro13-7410 was detected by telomerase PCRELISA-kit. The cell cycle was analyzed by flow cytometry. Results: Telomerase activity declined gradually after 10-6 mol/L Ro13-7410 treatment, and the inhibition of telomerase activity at day 5 of treatment with Ro13-7410 was less effective than with Retinoid Acid (RA).DNA flow cytofluorimetric analysis revealed that Ro13-7410 caused partial cells arrest in the G2/M phase after 4-days treatment. Conclusion: Telomerase activity declined gradually and partial cells were arrested in the G2/M phase after Ro13-7410 treatment.

  4. Phosphorylation of TPP1 regulates cell cycle-dependent telomerase recruitment

    OpenAIRE

    Zhang, Yi; Chen, Liuh-Yow; Han, Xin; XIE, Wei; Kim, Hyeung; Yang, Dong; Liu, Dan; Songyang, Zhou

    2013-01-01

    Telomere maintenance is essential for organisms with linear chromosomes and is carried out by telomerase during cell cycle. The precise mechanism by which cell cycle controls telomeric access of telomerase and telomere elongation in mammals remains largely unknown. Previous work has established oligonucleotide/oligosaccharide binding (OB) fold-containing telomeric protein TPP1, formerly known as TINT1, PTOP, and PIP1, as a key factor that regulates telomerase recruitment and activity. However...

  5. POT1–TPP1 enhances telomerase processivity by slowing primer dissociation and aiding translocation

    OpenAIRE

    Latrick, Chrysa M; Cech, Thomas R.

    2010-01-01

    Telomerase contributes to chromosome end replication by synthesizing repeats of telomeric DNA, and the telomeric DNA-binding proteins protection of telomeres (POT1) and TPP1 synergistically increase its repeat addition processivity. To understand the mechanism of increased processivity, we measured the effect of POT1–TPP1 on individual steps in the telomerase reaction cycle. Under conditions where telomerase was actively synthesizing DNA, POT1–TPP1 bound to the primer decreased primer dissoci...

  6. Detection of telomerase activity in Plasmodium falciparum using a nonradioactive method

    Directory of Open Access Journals (Sweden)

    Rubiano Claudia C

    2003-01-01

    Full Text Available A simple, quick and sensitive method was used to detect telomerase activity in Plasmodium falciparum. The telomeric repeat amplification protocol (TRAP assay was modified using electrophoresis and staining with SYBR-green I to detect telomerase activity in a range of 10² to 10(7 parasites. This might be a useful way to ascertain telomerase activity in different types of nontumor cells.

  7. Telomerase in pulmonary fibrosis. A link to alveolar cell apoptosis and differentiation

    OpenAIRE

    Argyris Tzouvelekis; Andreas Karameris; Evangelos Tsiambas; Anastasios Koutsopoulos; Rodoula Tringidou; Marios Froudarakis; Dimitrios Mikroulis; George Zacharis; Paschalis Steiropoulos; Ioanna Bazdiara; Constantinos Tsatalas; Ioannis Kotsianidis; Demosthenes Bouros

    2010-01-01

    SUMMARY. Introduction: Telomerase is crucial for extended life span and differentiation and is linked to immortality. Therefore, its role may be crucial in the pathogenesis of pulmonary fibrosis. Our objective was to implicate telomerase in the pathogenesis of idiopathic fibrotic lung disease. Patients and Methods: Assessment of telomerase activity and expression was carried out using TRAP detection kit and qRT-PCR. Experimental procedure was enhanced by a series of immunostainings and fluore...

  8. Immortalization of Neural Precursors When Telomerase Is Overexpressed in Embryonal Carcinomas and Stem Cells

    OpenAIRE

    Schwob, Anneke E.; Nguyen, Lilly J.; Meiri, Karina F.

    2008-01-01

    The DNA repair enzyme telomerase maintains chromosome stability by ensuring that telomeres regenerate each time the cell divides, protecting chromosome ends. During onset of neuroectodermal differentiation in P19 embryonal carcinoma (EC) cells three independent techniques (Southern blotting, Q-FISH, and Q-PCR) revealed a catastrophic reduction in telomere length in nestin-expressing neuronal precursors even though telomerase activity remained high. Overexpressing telomerase protein (mTERT) pr...

  9. Telomerase activity: A biomarker of cell proliferation, not malignant transformation

    OpenAIRE

    Belair, Cassandra D.; Yeager, Thomas R.; Lopez, Patricia M.; Reznikoff, Catherine A.

    1997-01-01

    Telomerase activity is readily detected in most cancer biopsies, but not in premalignant lesions or in normal tissue samples with a few exceptions that include germ cells and hemopoietic stem cells. Telomerase activity may, therefore, be a useful biomarker for diagnosis of malignancies and a target for inactivation in chemotherapy or gene therapy. These observations have led to the hypothesis that activation of telomerase may be an important step in tumorigenesis. To test this hypothesis, we ...

  10. Inhibition of cell proliferation and induction of apoptosis by oleanane triterpenoid (CDDO-Me) in pancreatic cancer cells is associated with the suppression of hTERT gene expression and its telomerase activity

    Energy Technology Data Exchange (ETDEWEB)

    Deeb, Dorrah; Gao, Xiaohua; Liu, Yongbo [Department of Surgery, Henry Ford Health System, Detroit, MI (United States); Kim, Sahn-Ho [Department of Urology, Henry Ford Health System, Detroit, MI (United States); Pindolia, Kirit R. [Department of Medical Genetics, Henry Ford Health System, Detroit, MI (United States); Arbab, Ali S. [Department of Radiology, Henry Ford Health System, Detroit, MI (United States); Gautam, Subhash C., E-mail: sgautam1@hfhs.org [Department of Surgery, Henry Ford Health System, Detroit, MI (United States)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT gene expression. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT protein expression. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT telomerase activity. Black-Right-Pointing-Pointer CDDO-Me inhibits hTERT regulatory proteins. -- Abstract: Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is a multifunctional oleanane synthetic triterpenoid with potent anti-inflammatory and antitumorigenic properties. The mechanisms of the antisurvival and apoptosis-inducing activities of CDDO-Me and related derivatives of oleanolic acid have been defined; however, to date, no study has been carried out on the effect of CDDOs on human telomerase reverse transcriptase (hTERT) gene or telomerase activity. Here we report for the first time that inhibition of cell proliferation and induction of apoptosis by CDDO-Me in pancreatic cancer cell lines is associated with the inhibition of hTERT gene expression, hTERT telomerase activity and a number of proteins that regulate hTERT expression and activity. Furthermore, abrogation or overexpression of hTERT protein altered the susceptibility of tumor cells to CDDO-Me. These findings suggest that telomerase (hTERT) is a relevant target of CDDO-Me in pancreatic cancer cells.

  11. Inhibition of cell proliferation and induction of apoptosis by oleanane triterpenoid (CDDO-Me) in pancreatic cancer cells is associated with the suppression of hTERT gene expression and its telomerase activity

    International Nuclear Information System (INIS)

    Highlights: ► CDDO-Me inhibits hTERT gene expression. ► CDDO-Me inhibits hTERT protein expression. ► CDDO-Me inhibits hTERT telomerase activity. ► CDDO-Me inhibits hTERT regulatory proteins. -- Abstract: Methyl-2-cyano-3,12-dioxooleana-1,9(11)-dien-28-oate (CDDO-Me) is a multifunctional oleanane synthetic triterpenoid with potent anti-inflammatory and antitumorigenic properties. The mechanisms of the antisurvival and apoptosis-inducing activities of CDDO-Me and related derivatives of oleanolic acid have been defined; however, to date, no study has been carried out on the effect of CDDOs on human telomerase reverse transcriptase (hTERT) gene or telomerase activity. Here we report for the first time that inhibition of cell proliferation and induction of apoptosis by CDDO-Me in pancreatic cancer cell lines is associated with the inhibition of hTERT gene expression, hTERT telomerase activity and a number of proteins that regulate hTERT expression and activity. Furthermore, abrogation or overexpression of hTERT protein altered the susceptibility of tumor cells to CDDO-Me. These findings suggest that telomerase (hTERT) is a relevant target of CDDO-Me in pancreatic cancer cells.

  12. Study on the mechanism of cytotoxic effects of radiation and chemicals and development of risk assessment method. Changes in telomere and telomerase in mutated animals

    International Nuclear Information System (INIS)

    It has been known that the carcinogenic risk for radiation, chemical agents, etc. of Mus musulus molossinus MUG (MUG) maintained in laboratory is comparatively low compared with laboratory strains of mouse although the cause is not unclear. Here, aiming to develop a new assessment system for general risk including biological effects of radiation, chemical agents, etc., an investigation was made on the length of telomere and the telomerase activity. Three strains of laboratory mouse, C57BL/6, C3H and DBA, and molossinus were used as the subjects. Whole DNA was extracted from various organs; brain, lung, thymus, spleen, liver, kidney and testis, and the length of telomere was determined by Southern blotting method using a probe to recognize the telomere sequence. The telomere length of MUG was about 40 Kb for any DNA from the organs examined. This length (40 Kb) was much longer than the length in human cord blood lymphocyte. However, there was no difference in the telomere length between the three laboratory strains and MUG. The activity of telomerase was carried out by fluorescence telomeric repeat amplification protocol method, which is a slightly modified method of the conventional one. Highly accurate determination of telomerase activity was possible by the use of fluorescent sequencer. As to the liver, telomerase activity was lower (50%) in MUG than the laboratory strains, but there was no difference in the activities in other organs among those strains. Thus, it was suggested that the difference in telomerase activity in the liver might be related to the low carcinogenic risk of MUG. (M.N.)

  13. Fibroblast growth factor receptor 3 effects on proliferation and telomerase activity in sheep growth plate chondrocytes

    Directory of Open Access Journals (Sweden)

    Smith Logan B

    2012-12-01

    Full Text Available Abstract Background Fibroblast growth factor receptor 3 (FGFR3 inhibits growth-plate chondrocyte proliferation and limits bone elongation. Gain-of-function FGFR3 mutations cause dwarfism, reduced telomerase activity and shorter telomeres in growth plate chondroyctes suggesting that FGFR3 reduces proliferative capacity, inhibits telomerase, and enhances senescence. Thyroid hormone (T3 plays a role in cellular maturation of growth plate chondrocytes and a known target of T3 is FGFR3. The present study addressed whether reduced FGFR3 expression enhanced telomerase activity, mRNA expression of telomerase reverse transcriptase (TERT and RNA component of telomerase (TR, and chondrocyte proliferation, and whether the stimulation of FGFR3 by T3 evoked the opposite response. Results Sheep growth-plate proliferative zone chondrocytes were cultured and transfected with siRNA to reduce FGFR3 expression; FGFR3 siRNA reduced chondrocyte FGFR3 mRNA and protein resulting in greater proliferation and increased TERT mRNA expression and telomerase activity (p 3 significantly enhanced FGFR3 mRNA and protein expression and reduced telomerase activity (p 3 at the growth plate may be partially mediated through the FGFR3 pathway. Conclusions The results suggest that FGFR3 inhibits chondrocyte proliferation by down-regulating TERT expression and reducing telomerase activity indicating an important role for telomerase in sustaining chondrocyte proliferative capacity during bone elongation.

  14. TELOMERASE ACTIVITY IN COLORECTAL CARCINOMA AND ITS CORRELATION WITH EXPRESSION OF C-MYC

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Lun; GE Lian-ying; ZHANG Gui-nian

    2005-01-01

    Objective: To study the role of telomerase activity and c-myc in pathogenesis and progression of colorectal carcinoma,and to investigate the possible regulatory mechanism of telomerase activation. Methods: A modified telomeric repeat amplification protocol (TRAP) and immunohistochemical staining was used to detect telomerase activity and the expression of c-myc in tissue samples from colorectal carcinoma, paracarcinomatousl tissues, normal mucosa, and adenomatoid polyp.Results: The positive rates of telomerase activity and c-myc expression were 83.33% and 80.00% in colorectal carcinoma,13.33% and 23.33% in paracarcinomatousl tissues, 13.33% and 20.00% in normal mucosa, and 10.00% and 45.00% in adenomatoid polyp respectively, they were significantly higher in colorectal carcinoma than in paracarcinomatousl tissues,normal mucosa, and adenomatoid polyp (P<0.05). The rates of telomerase activity and c-myc expression were much higher in colorectal carcinoma with lymph nodes metastases than that without lymph nodes metastases. The expression of c-myc was found being significantly higher in the telomerase positive colorectal carcinoma than in the telomerase negative group(P<0.05). Conclusion: The activation of telomerase and abnormal expression of c-myc might play an important role in the process of carcinogenesis and progression of colorectal carcinoma. The over-expression of c-myc may be related to telomerase activation and up-regulation in colorectal carcinoma.

  15. Interaction between Bovine leukemia virus (BLV) infection and age on telomerase misregulation.

    Science.gov (United States)

    Hemmatzadeh, Farhid; Keyvanfar, Hadi; Hasan, Noor Haliza; Niap, Faustina; Bani Hassan, Ebrahim; Hematzade, Azar; Ebrahimie, Esmaeil; McWhorter, Andrea; Ignjatovic, Jagoda

    2015-06-01

    Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis (EBL). BLV can interact with telomerase and inhibits telomere shortening, contributing in leukemogenesis and tumour induction. The role of telomerase in BLV-induced lymphosarcoma and aging has been extensively studied. To date, the interaction of both BLV and aging on telomerase mis-regulation have, however, not been investigated. In the present study, telomerase activity in BLV positive and negative cows was compared over a wide range of ages (11-85 months). Lymphocyte counts were also measured in both BLV positive and negative groups. Telomerase activity was detected in all BLV infected animals with persistent lymphocytosis (PL), especially in older individuals. This study revealed that the cells undergo the natural telomerase shortening even in the presence of an existing viral infection. We also show that viral infection, especially during the PL phase of the disease, increases telomerase activity. A statistically significant interaction between age and viral infection was observed for telomere shortening during BLV infection. Older animals with BLV infection, especially those with persistent lymphocytosis or visible tumors, exhibited a sharp increase in telomerase activity. This study demonstrates that there is a significant interaction between BLV infection and telomerase up-regulation and lymphocytosis. PMID:25665900

  16. Effects of exogenous ATM gene on mRNA expression of human telomerase reverse transcriptase in AT cells induced by irradiation%外源性ATM基因对辐射诱导AT细胞端粒酶逆转录酶mRNA表达的影响

    Institute of Scientific and Technical Information of China (English)

    盛方军; 曹建平; 罗加林; 朱巍; 刘芬菊; 冯爽; 宋建元; 李翀

    2005-01-01

    通过观察外源性毛细血管扩张性共济失调症突变基因(Ataxia-telangiectasia mutation,ATM)对毛细血管扩张性共济失调症(Ataxia-telangiectasia,AT)患者皮肤的成纤维细胞系AT5BIVA(AT细胞)端粒酶逆转录酶(human telomerase reverse transcriptase,hTERT)mRNA表达的影响,探讨ATM对hTERT的调控作用.采用RT-PCR法,对比ATM基因转染前、后AT细胞hTERTmRNA表达的变化及与源自正常人皮肤的成纤维细胞系GM0639(GM细胞)相比的差异;以及细胞经3 Gy60Co γ射线照射后其hTERT mRNA表达的变化.结果显示,未照射时,GM细胞hTERT mRNA表达呈阴性,AT细胞hTERT mRNA表达呈阳性,转染ATM基因后的ATM+-AT细胞其hTERT mRNA的表达明显下降(p<0.05);60Coγ射线照射后,GM细胞hTERTmRNA表达呈阳性,AT细胞、空载体AT细胞(PEBS7-AT细胞)和ATM+-AT细胞hTERT mRNA的表达量比未照射时明显增加(p<0.05),ATM+-AT细胞hTERT mRNA相对表达量的增加低于AT细胞和空载体AT细胞(p<0.05).提示ATM可下调hTERT mRNA的表达;电离辐射可诱导细胞hTERT mRNA表达;端粒酶参与DNA损伤修复.

  17. Amyloid Beta-Mediated Hypomethylation of Heme Oxygenase 1 Correlates with Cognitive Impairment in Alzheimer’s Disease

    Science.gov (United States)

    Sung, Hye Youn; Choi, Byung-Ok; Jeong, Jee Hyang; Kong, Kyoung Ae; Hwang, Jinha; Ahn, Jung-Hyuck

    2016-01-01

    To identify epigenetically regulated genes involved in the pathogenesis of Alzheimer’s disease (AD) we analyzed global mRNA expression and methylation profiles in amyloid precursor protein (APP)-Swedish mutant-expressing AD model cells, H4-sw and selected heme oxygenase-1 (HMOX1), which is associated with pathological features of AD such as neurofibrillary tangles and senile plaques. We examined the epigenetic regulatory mechanism of HMOX1 and its application as a diagnostic and prognostic biomarker for AD. Our results show that HMOX1 mRNA and protein expression was approximately 12.2-fold and 7.9-fold increased in H4-sw cells, respectively. Increased HMOX1 expression was also detected in the brain, particularly the hippocampus, of AD model transgenic mice. However, the methylation of specific CpG sites within its promoter, particularly at CpG located −374 was significantly decreased in H4-sw cells. Treatment of neuroglioma cells with the demethylating agent 5-aza-2′-deoxycytidine resulted in reduced methylation of HMOX1 promoter accompanied by enhanced HMOX1 expression strongly supporting DNA methylation-dependent transcriptional regulation of HMOX1. Toxic Aβ-induced aberrant hypomethylation of HMOX1 at −374 promoter CpG site was correlated with increased HMOX1expression. In addition to neuroglioma cells, we also found Aβ-induced epigenetic regulation of HMOX1 in human T lymphocyte Jurkat cells. We evaluated DNA methylation status of HMOX1 at −374 promoter CpG site in blood samples from AD patients, patients with mild cognitive impairment (MCI), and control individuals using quantitative methylation-specific polymerase chain reaction. We observed lower methylation of HMOX1 at the −374 promoter CpG site in AD patients compared to MCI and control individuals, and a correlation between Mini-Mental State Examination score and demethylation level. Receiver operating characteristics analysis revealed good discrimination of AD patients from MCI patients and

  18. A telomerase em células-tronco hematopoéticas Telomerase in hematopoietic stem cells

    Directory of Open Access Journals (Sweden)

    Silvana Perini

    2008-02-01

    Full Text Available A proliferação das células-tronco hematopoéticas sofre a perda dos telômeros a cada divisão celular. Alguns autores discordam quanto à perda ou não do potencial proliferativo e capacidade de auto-renovação das células mais diferenciadas. Revisaremos aqui o papel da telomerase na biologia do sistema hematopoético, na diferenciação normal ou maligna, assim como no envelhecimento das células-tronco hematopoéticas. A constante renovação celular requerida pela hematopoese confere às células-tronco embrionárias, assim como à maioria das células tumorais, um aumento da capacidade proliferativa marcada pela detecção da enzima telomerase e possível manutenção dos telômeros. Estudos clínicos se farão necessários para esclarecer melhor a atividade da telomerase em células-tronco hematopoéticas, seu possível uso como marcador de diagnóstico e seu uso a fim de propósitos prognósticos.Hematopoietic stem cell proliferation leads to telomere length decreases at each cellular division. Some authors disagree about the telomere influence on the reduction of the proliferative potential and capacity of self renewal. Here we review telomerase function in the biology of the hematopoietic system, in normal or differentiation and its influence on the ageing of hematopoietic stem cells. The constant cellular renewal required to maintain the hematopoietic system, provides embryonic stem cells, as well as malignant cells, an increased proliferative capacity. This is marked by the detection of telomerase enzyme activity and possible telomere maintenance. Clinical trials will be required to clarify telomerase activity in hematopoietic stem cells, its possible use as a diagnostic marker and its use for prognostic purposes.

  19. Relationship between telomere length and radiosensitivity of human cancer cell lines induced by heavy ion irradiation

    International Nuclear Information System (INIS)

    Telomere length is associated with both cancer incidence and cancer mortality. Low linear energy transfer (LET) induced telomere shortening and change in telomerase activity have been studied. However, no information about high LET induced telomere length and telomerase activity alteration was available currently. Here we investigated carbon ions irradiation induced telomerase activity and its expression in mRNA and protein levels. Results indicated that one of the components for telomerase, human telomerase reverse transcriptase (hTERT), was significantly affected by carbon ions irradiation, thus regulated telomerase activity after ionizing irradiation. For further investigate factors involved in telomerase activity, four different cell lines were used. BRCA1 and DNA-PK have been identified to be associated with telomerase activity regulation. In summary, the radiosensitivity of human cancer cell lines after carbon ions irradiation is related to telomerase activity, which is directly regulated by hTERT expression, BRCA1 and DNA-PK statues may play important parts in this regulation. (author)

  20. Photosensitized damage to telomere overhang and telomerase RNA by riboflavin

    Institute of Scientific and Technical Information of China (English)

    Yuxia Liu; Fuqiang Du; Weizhen Lin; Tiecheng Tu; Wenxin Li; Nianyun Lin

    2008-01-01

    By ESR spin elimination and photodeavage assay, the mechanisms of one-electron oxidation damage of oligonucleotides by excited triplet state of riboflavin (Rb) have been elucidated. The results demonstrate that Rb, an endogenous photosensitizer, is capable of cleaving single-stranded telomeric overhang and the template region of telomerase RNA under UVA irradiation, resulting in blocking of reverse transcription of telomeric DNA which leads to the apoptosis of cancer cells ultimately.

  1. HMGB1 associates with TERT and stimulates telomerase activity

    Czech Academy of Sciences Publication Activity Database

    Kunická, Zuzana; Muselíková Polanská, Eva; Dvořáčková, Martina; Štros, Michal; Fajkus, Jiří

    Cold Spring Harbor, 2007. s. 85-85. [Telomeres & Telomerase. 02.05.2007-06.05.2007, Cold Spring Harbor] R&D Projects: GA ČR(CZ) GA521/05/0055; GA ČR(CZ) GA204/05/2031 Institutional research plan: CEZ:AV0Z50040507 Keywords : telomere * chromatin * high-mobility-group protein Subject RIV: BO - Biophysics

  2. Effects of telomerase expression on photodynamic therapy of Barrett's esophagus

    Science.gov (United States)

    Wang, Kenneth K.; Anderson, Marlys; Buttar, Navtej; WongKeeSong, Louis-Michel; Borkenhagen, Lynn; Lutzke, Lori

    2003-06-01

    Photodynamic therapy has been applied to Barrett's esophagus and has been shown in prospective randomized studies to eliminate dysplasia as well as decrease the occurrence of cancer. However, the therapy isnot always effective and there are issues with residual areas of Barrett's mucosa despite therapy. There has not been a good explanation for these residual areas and they seem to imply that there may exist a biological mechanisms by which these cells may be resistant to photodynamic therapy. It was our aim to determine if known abnormalities in Barrett's mucosa could be correlated with the lack of response of some of these tissues. We examined the tissue from mulitpel patients who had resonse to therapy as well as those who did not respond. We assessed the tissue for p53 mutations, inactivatino of p16, ploidy status, cell proliferation, telomerase activity, and degree of dysplasia. Interestingly, the only genetic marker than was found to be correlated with lack of reonse was p53 and telomerase activity. This suggests that cells that have lost mechanisms for cell death such as apoptosis or telomere shortengin may be more resistant to photodynamic therapy. In this study, we examined patients before and after PDT for telomerase activity.

  3. hTERT phosphorylation by PKC is essential for telomerase holoprotein integrity and enzyme activity in head neck cancer cells

    OpenAIRE

    Chang, J T; Lu, Y-C; Chen, Y-J; Tseng, C-P; Chen, Y-L; Fang, C-W; Cheng, A-J

    2006-01-01

    Telomerase activity is suppressed in normal somatic tissues but is activated in most cancer cells. We have previously found that all six telomerase subunit proteins, including hTERT and hsp90 are needed for full enzyme activity. Telomerase activity has been reported to be upregulated by protein kinase C (PKC), but the mechanism is not clear. In this study, we examined how PKC regulates telomerase activity in head and neck cancer cells. PKC inhibitor, bisindolylmaleimide I (BIS), inhibited tel...

  4. Involvement of SRSF11 in cell cycle-specific recruitment of telomerase to telomeres at nuclear speckles

    OpenAIRE

    Lee, Ji Hoon; Jeong, Sun Ah; Khadka, Prabhat; Hong, Juyeong; Chung, In Kwon

    2015-01-01

    Telomerase, a unique ribonucleoprotein complex that contains the telomerase reverse transcriptase (TERT), the telomerase RNA component (TERC) and the TERC-binding protein dyskerin, is required for continued cell proliferation in stem cells and cancer cells. Here we identify SRSF11 as a novel TERC-binding protein that localizes to nuclear speckles, subnuclear structures that are enriched in pre-messenger RNA splicing factors. SRSF11 associates with active telomerase enzyme through an interacti...

  5. Troglitazone suppresses telomerase activity independently of PPARγ in estrogen-receptor negative breast cancer cells

    Directory of Open Access Journals (Sweden)

    Nguyen Johnny

    2010-07-01

    Full Text Available Abstract Background Breast cancer is one the highest causes of female cancer death worldwide. Many standard chemotherapeutic agents currently used to treat breast cancer are relatively non-specific and act on all rapidly dividing cells. In recent years, more specific targeted therapies have been introduced. It is known that telomerase is active in over 90% of breast cancer tumors but inactive in adjacent normal tissues. The prevalence of active telomerase in breast cancer patients makes telomerase an attractive therapeutic target. Recent evidence suggests that telomerase activity can be suppressed by peroxisome proliferator activated receptor gamma (PPARγ. However, its effect on telomerase regulation in breast cancer has not been investigated. Methods In this study, we investigated the effect of the PPARγ ligand, troglitazone, on telomerase activity in the MDA-MB-231 breast cancer cell line. Real time RT-PCR and telomerase activity assays were used to evaluate the effect of troglitazone. MDA-MB-231 cells had PPARγ expression silenced using shRNA interference. Results We demonstrated that troglitazone reduced the mRNA expression of hTERT and telomerase activity in the MDA-MB-231 breast cancer cell line. Troglitazone reduced telomerase activity even in the absence of PPARγ. In agreement with this result, we found no correlation between PPARγ and hTERT mRNA transcript levels in breast cancer patients. Statistical significance was determined using Pearson correlation and the paired Student's t test. Conclusions To our knowledge, this is the first time that the effect of troglitazone on telomerase activity in breast cancer cells has been investigated. Our data suggest that troglitazone may be used as an anti-telomerase agent; however, the mechanism underlying this inhibitory effect remains to be determined.

  6. Troglitazone suppresses telomerase activity independently of PPARγ in estrogen-receptor negative breast cancer cells

    International Nuclear Information System (INIS)

    Breast cancer is one the highest causes of female cancer death worldwide. Many standard chemotherapeutic agents currently used to treat breast cancer are relatively non-specific and act on all rapidly dividing cells. In recent years, more specific targeted therapies have been introduced. It is known that telomerase is active in over 90% of breast cancer tumors but inactive in adjacent normal tissues. The prevalence of active telomerase in breast cancer patients makes telomerase an attractive therapeutic target. Recent evidence suggests that telomerase activity can be suppressed by peroxisome proliferator activated receptor gamma (PPARγ). However, its effect on telomerase regulation in breast cancer has not been investigated. In this study, we investigated the effect of the PPARγ ligand, troglitazone, on telomerase activity in the MDA-MB-231 breast cancer cell line. Real time RT-PCR and telomerase activity assays were used to evaluate the effect of troglitazone. MDA-MB-231 cells had PPARγ expression silenced using shRNA interference. We demonstrated that troglitazone reduced the mRNA expression of hTERT and telomerase activity in the MDA-MB-231 breast cancer cell line. Troglitazone reduced telomerase activity even in the absence of PPARγ. In agreement with this result, we found no correlation between PPARγ and hTERT mRNA transcript levels in breast cancer patients. Statistical significance was determined using Pearson correlation and the paired Student's t test. To our knowledge, this is the first time that the effect of troglitazone on telomerase activity in breast cancer cells has been investigated. Our data suggest that troglitazone may be used as an anti-telomerase agent; however, the mechanism underlying this inhibitory effect remains to be determined

  7. Telomere Length, Telomerase Activity, and Replicative Potential in HIV Infection: Analysis of CD4+ and CD8+T Cells from HIV-discordant Monozygotic Twins

    OpenAIRE

    Palmer, Larry D.; Weng, Nan-ping; Levine, Bruce L.; June, Carl H; Lane, H. Clifford; Hodes, Richard J.

    1997-01-01

    To address the possible role of replicative senescence in human immunodeficiency virus (HIV) infection, telomere length, telomerase activity, and in vitro replicative capacity were assessed in peripheral blood T cells from HIV+ and HIV− donors. Genetic and age-specific effects on these parameters were controlled by studying HIV-discordant pairs of monozygotic twins. Telomere terminal restriction fragment (TRF) lengths from CD4+ T cells of HIV+ donors were significantly greater than those from...

  8. Increase in Viral Load, Viral Integration, and Gain of Telomerase Genes during Uterine Cervical Carcinogenesis can be Simultaneously Assessed by the HPV 16/18 MLPA-Assay

    OpenAIRE

    Theelen, Wendy; Speel, Ernst-Jan M; Herfs, Michael; Reijans, Martin; Simons, Guus; Meulemans, Els V.; Baldewijns, Marcella M.; Ramaekers, Frans C. S.; Somja, Joan; Delvenne, Philippe; Hopman, Anton H. N.

    2010-01-01

    Oncogenic human papillomavirus (HPV) infection is the most important risk factor in cervical carcinogenesis cases; high viral loads, viral integration into the host genome, and gain of the telomerase-related genes, TERT and TERC, are all factors associated with progression to cancer. A recently developed multiparameter HPV 16/18 multiplex ligation-dependent probe amplification (MLPA) assay, which allows the simultaneous assessment of these factors, was applied to a series of 67 normal and (pr...

  9. Switch telomerase to ALT mechanism by inducing telomeric DNA damages and dysfunction of ATRX and DAXX.

    Science.gov (United States)

    Hu, Yang; Shi, Guang; Zhang, Laichen; Li, Feng; Jiang, Yuanling; Jiang, Shuai; Ma, Wenbin; Zhao, Yong; Songyang, Zhou; Huang, Junjiu

    2016-01-01

    Activation of telomerase or alternative lengthening of telomeres (ALT) is necessary for tumours to escape from dysfunctional telomere-mediated senescence. Anti-telomerase drugs might be effective in suppressing tumour growth in approximately 85-90% of telomerase-positive cancer cells. However, there are still chances for these cells to bypass drug treatment after switching to the ALT mechanism to maintain their telomere integrity. But the mechanism underlying this switch is unknown. In this study, we used telomerase-positive cancer cells (HTC75) to discover the mechanism of the telomerase-ALT switch by inducing telomere-specific DNA damage, alpha-thalassemia X-linked syndrome protein (ATRX) knockdown and deletion of death associated protein (DAXX). Surprisingly, two important ALT hallmarks in the ALT-like HTC75 cells were observed after treatments: ALT-associated promyelocytic leukaemia bodies (APBs) and extrachromosomal circular DNA of telomeric repeats. Moreover, knocking out hTERT by utilizing the CRISPR/Cas9 technique led to telomere elongation in a telomerase-independent manner in ALT-like HTC75 cells. In summary, this is the first report to show that inducing telomeric DNA damage, disrupting the ATRX/DAXX complex and inhibiting telomerase activity in telomerase-positive cancer cells lead to the ALT switch. PMID:27578458

  10. Rapid and quantitative measuring of telomerase activity using an electrochemiluminescent sensor

    Science.gov (United States)

    Zhou, Xiaoming; Xing, Da; Zhu, Debin; Jia, Li

    2007-11-01

    Telomerase, a ribonucleoprotein enzyme that adds telomeric repeats to the 3'end of chromosomal DNA for maintaining chromosomal integrity and stability. This strong association of telomerase activity with tumors establishing it is the most widespread cancer marker. A number of assays based on the polymerase chain reaction (PCR) have been developed for the evaluation of telomerase activity. However, those methods require gel electrophoresis and some staining procedures. We developed an electrochemiluminescent (ECL) sensor for the measuring of telomerase activity to overcome these problems such as troublesome post-PCR procedures and semi-quantitative assessment in the conventional method. In this assay 5'-biotinylated telomerase synthesis (TS) primer serve as the substrate for the extension of telomeric repeats under telomerase. The extension products were amplified with this TS primer and a tris-(2'2'-bipyridyl) ruthenium (TBR)-labeled reversed primer. The amplified products was separated and enriched in the surface of electrode by streptavidin-coated magnetic beads, and detected by measuring the ECL signals of the TBR labeled. Measuring telomerase activity use the sensor is easy, sensitive, rapid, and applicable to quantitative analysis, should be clinically useful for the detection and monitoring of telomerase activity.

  11. Telomerase activity in colorectal cancer, prognostic factor and implications in the microsatellite instability pathway

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To determine whether the telomerase activity is related to the Microsatellite instability (MSI) genetic pathway and whether it means a difference in the survival.METHODS: The population consisted of 97 colorectal cancer patients. MSI determination was performed in accordance with the NCI criteria using PCR and Genescan. Telomerase activity was determined by the TRAP-assay, an ELISA procedure based on the amplification of telomeric repeat sequences.RESULTS: 6.2% showed high MSI (MSI-H), 10.3% showed low MSI (MSI-L) and 83.5% did not show this alteration (MSS). Positive telomerase activity was detected in 92.8% of the patients. 83.3% of MSI-H tumors showed positive telomerase against 93.8% of MSS tumors. In the overall survival analysis the absence of telomerase activity conferred a better prognosis.CONCLUSION: Previous works have shown that tumors which develop via the MSI pathway present a better prognosis. No link between telomerase activity and MSI status is observed, although sample sizes are small.Patients with telomerase negative tumors had better overall survival than patients with telomerase positive tumors.

  12. EFFECTS OF THE HYPERTHERMIA AND HARRINGTONINE ON TELOMERASE ACTIVITY OF HL-60 CELLS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Objective:To understand the mechanism of the hypertherjia and harringtonine in purging of leukemia cells In vitro.telomerase activity of HL-60 cells treated by hyperthermia(42℃ for one hour) and different concentrations of Harringtonine were investigated .Methods Using telomeric Repeats Amplification Protocol(TRAP)and ELISA techniques to analyze the telomerase activity of HL-60 cells,Results:Our results showed that harringtonine inhibited the telomerase activity of HL-60 cells in a dosage related manner,Moreover,the telomerase activity of HL-60 cells was significantly decreased after the hyperthermia treatment as compared with untreated cells.Conclusion:The effect of the hyperthermia and Harringtonine on purging leukemia cellsIn vitro may be mediated by down regulation of telomerase activity of tumor cells.

  13. TELOMERASE ACTIVITY DURING 7, 12-DIMETHYLBENZ [a] ANTHRACENE-INDUCED HAMSTER BUCCAL POUCH CARCINOGENESIS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective: To investigate the roles of telomerase activity (TA) in relation to hamster buccal pouch tumor progression. Methods: male hamster were treated three times weekly with 0.5% of 7, 12-dimethyl- benzanthracene (DMBA) over a 15 weeks experimental period. Hamsters were sacrificed at 3, 6, 9, 12 and 15 weeks after treatment. Telomerase activity of hamster buccal pouch tissue were measured along with the analyses of the formation of DMBA-induced hamster buccal pouch tumors. Results: DMBA-induced squamous cell carcinomas were found at the 6th week after dosing. Telomerase activity elevation began at the 3rd week and was increasing to a plateau at the 12th week. Conclusion: Our results show that telomerase activity in the target tissue may be detected at the early stage of the DMBA-induced hamster buccal pouch tumor formation and suggests that telomerase activity may be used as a biomarker for an early clinical detection of buccal pouch cancer.

  14. Detection of telomerase activity by combination of telomeric repeat amplification protocol and electrochemiluminescence assay

    Institute of Scientific and Technical Information of China (English)

    Xiao Ming Zhou; Li Jia

    2008-01-01

    A highly sensitive telomerase detection method that combines telomeric repeat amplification protocol (TRAP) and magnetic beads based electrochemiluminescence (ECL) assay has been developed. Briefly, telomerase recognizes biotinylated telomerase synthesis primer (B-TS) and synthesizes extension products, which then serve as the templates for PCR amplification using B-TS as the forward primer and Iris-(2'2'-bipyridyl) ruthenium (TBR) labeled ACX (TBR-ACX) as the reversed primer. The amplified product is captured on streptavidin-coated paramagnetic beads and detected by ECL. Telomerase positive HeLa cells were used to validate the feasibility of the method. The experimental results showed down to 10 cancer cells can be detected easily. The method is a useful tool for telomerase activity analysis due to its sensitivity, rapidity, safety, high throughput, and low cost. It can be used for screening a large amount of clinical samples.

  15. Transgenic rat model of childhood-onset dermatitis by overexpressing telomerase reverse transcriptase (TERT).

    Science.gov (United States)

    Kaneko, Ryosuke; Sato, Atsuko; Hamada, Shun; Yagi, Takeshi; Ohsawa, Ichiro; Ohtsuki, Mamitaro; Kobayashi, Eiji; Hirabayashi, Masumi; Murakami, Takashi

    2016-08-01

    Childhood-onset dermatitis is one of the most common skin disorders in children. Although various mouse models that mirror aspects of dermatitis have become available, there is still a need for an animal model that develops dermatitis in childhood and is more suitable for performing tissue transplantation experiments. There is emerging evidence that peripheral blood T lymphocytes from patients with dermatitis have significantly increased telomerase activity. Here, we developed telomerase reverse transcriptase (TERT)-expressing transgenic (Tg) rats that spontaneously developed eczematous skin inflammation in childhood. Newborn TERT-Tg rats developed visible dermatitis in 56 % of cases, and the skin lesions microscopically showed spongiosis and acanthosis with infiltration of lymphocytes, eosinophils and mast cells. TERT-Tg rats with dermatitis exhibited increased CD4 (2.5-fold) and CD8 (fivefold) T cell numbers compared with dermatitis-free TERT-Tg rats. Stronger TERT activity was observed in the peripheral lymphocytes of dermatitis-positive TERT-Tg rats than those of dermatitis-free TERT-Tg rats. RT-PCR analysis revealed that IL-4 was markedly elevated in the spleen of dermatitis-positive TERT-Tg rats, and that interferon-gamma was increased in the dermatitis lesions. Moreover, skin grafting of TERT-Tg rats with dermatitis onto T cell-deficient nude rats demonstrated that the inflamed skin lesions could not be maintained. Taken together, the results suggest that TERT activation in T lymphocytes is one of the potential predisposing factors for dermatitis. Moreover, our results demonstrated that the TERT-Tg rats mirror aspects of human childhood-onset dermatitis and that these animals represent a potential animal model system for studying childhood-onset dermatitis. PMID:26885830

  16. Tissue formation and tissue engineering through host cell recruitment or a potential injectable cell-based biocomposite with replicative potential: Molecular mechanisms controlling cellular senescence and the involvement of controlled transient telomerase activation therapies.

    Science.gov (United States)

    Babizhayev, Mark A; Yegorov, Yegor E

    2015-12-01

    Accumulated data indicate that wound-care products should have a composition equivalent to that of the skin: a combination of particular growth factors and extracellular matrix (ECM) proteins endogenous to the skin, together with viable epithelial cells, fibroblasts, and mesenchymal stem cells (MSCs). Strategies consisting of bioengineered dressings and cell-based products have emerged for widespread clinical use; however, their performance is not optimal because chronic wounds persist as a serious unmet medical need. Telomerase, the ribonucleoprotein complex that adds telomeric repeats to the ends of chromosomes, is responsible for telomere maintenance, and its expression is associated with cell immortalization and, in certain cases, cancerogenesis. Telomerase contains a catalytic subunit, the telomerase reverse transcriptase (hTERT). Introduction of TERT into human cells extends both their lifespan and their telomeres to lengths typical of young cells. The regulation of TERT involves transcriptional and posttranscriptional molecular biology mechanisms. The manipulation, regulation of telomerase is multifactorial in mammalian cells, involving overall telomerase gene expression, post-translational protein-protein interactions, and protein phosphorylation. Reactive oxygen species (ROS) have been implicated in aging, apoptosis, and necrosis of cells in numerous diseases. Upon production of high levels of ROS from exogenous or endogenous generators, the redox balance is perturbed and cells are shifted into a state of oxidative stress, which subsequently leads to modifications of intracellular proteins and membrane lipid peroxidation and to direct DNA damage. When the oxidative stress is severe, survival of the cell is dependent on the repair or replacement of damaged molecules, which can result in induction of apoptosis in the injured with ROS cells. ROS-mediated oxidative stress induces the depletion of hTERT from the nucleus via export through the nuclear pores

  17. 33. The Study of Mechanism By Which The Telomerase Template Phosphorothioate Antisense Oligonucleotide(TPAO) Inhibites The Growth of Tumor Cells

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@The length of telomere in cells is related to the regulation of life span. The activation of telomerase is required for the maintain of telemere. In the pass several years the studies revealed that the activation of telomerase was associated with initiation and progression of tumorigenesis. There was evident that telomerase inhibitors had the inhibitory effect on tumor cells. The regulation of telo-merase activation was probably associated with cyclins. There was evident that telomerase

  18. Telomerase activation by genomic rearrangements in high-risk neuroblastoma.

    Science.gov (United States)

    Peifer, Martin; Hertwig, Falk; Roels, Frederik; Dreidax, Daniel; Gartlgruber, Moritz; Menon, Roopika; Krämer, Andrea; Roncaioli, Justin L; Sand, Frederik; Heuckmann, Johannes M; Ikram, Fakhera; Schmidt, Rene; Ackermann, Sandra; Engesser, Anne; Kahlert, Yvonne; Vogel, Wenzel; Altmüller, Janine; Nürnberg, Peter; Thierry-Mieg, Jean; Thierry-Mieg, Danielle; Mariappan, Aruljothi; Heynck, Stefanie; Mariotti, Erika; Henrich, Kai-Oliver; Gloeckner, Christian; Bosco, Graziella; Leuschner, Ivo; Schweiger, Michal R; Savelyeva, Larissa; Watkins, Simon C; Shao, Chunxuan; Bell, Emma; Höfer, Thomas; Achter, Viktor; Lang, Ulrich; Theissen, Jessica; Volland, Ruth; Saadati, Maral; Eggert, Angelika; de Wilde, Bram; Berthold, Frank; Peng, Zhiyu; Zhao, Chen; Shi, Leming; Ortmann, Monika; Büttner, Reinhard; Perner, Sven; Hero, Barbara; Schramm, Alexander; Schulte, Johannes H; Herrmann, Carl; O'Sullivan, Roderick J; Westermann, Frank; Thomas, Roman K; Fischer, Matthias

    2015-10-29

    Neuroblastoma is a malignant paediatric tumour of the sympathetic nervous system. Roughly half of these tumours regress spontaneously or are cured by limited therapy. By contrast, high-risk neuroblastomas have an unfavourable clinical course despite intensive multimodal treatment, and their molecular basis has remained largely elusive. Here we have performed whole-genome sequencing of 56 neuroblastomas (high-risk, n = 39; low-risk, n = 17) and discovered recurrent genomic rearrangements affecting a chromosomal region at 5p15.33 proximal of the telomerase reverse transcriptase gene (TERT). These rearrangements occurred only in high-risk neuroblastomas (12/39, 31%) in a mutually exclusive fashion with MYCN amplifications and ATRX mutations, which are known genetic events in this tumour type. In an extended case series (n = 217), TERT rearrangements defined a subgroup of high-risk tumours with particularly poor outcome. Despite a large structural diversity of these rearrangements, they all induced massive transcriptional upregulation of TERT. In the remaining high-risk tumours, TERT expression was also elevated in MYCN-amplified tumours, whereas alternative lengthening of telomeres was present in neuroblastomas without TERT or MYCN alterations, suggesting that telomere lengthening represents a central mechanism defining this subtype. The 5p15.33 rearrangements juxtapose the TERT coding sequence to strong enhancer elements, resulting in massive chromatin remodelling and DNA methylation of the affected region. Supporting a functional role of TERT, neuroblastoma cell lines bearing rearrangements or amplified MYCN exhibited both upregulated TERT expression and enzymatic telomerase activity. In summary, our findings show that remodelling of the genomic context abrogates transcriptional silencing of TERT in high-risk neuroblastoma and places telomerase activation in the centre of transformation in a large fraction of these tumours. PMID:26466568

  19. Effective gene-viral therapy for telomerase-positive cancers by selective replicative-competent adenovirus combining with endostatin gene

    Institute of Scientific and Technical Information of China (English)

    Zhang Q; Liu C; Jiang M; Fang G; Liu X; Wu M; Qian Q; Nie M; Sham J; Su C; Xue H; Chua D; Wang W; Cui Z; Liu Y

    2005-01-01

    Gene-viral therapy, which uses replication-selective transgene-expressing viruses to manage tumors, can exploit the virtues of gene therapy and virotherapy and overcome the limitations of conventional gene therapy. Using a human telomerase reverse transcriptase-targeted replicative adenovirus as an antiangiogenic gene transfer vector to target new angiogenesis and making use of its unrestrained proliferation are completely new concepts in tumor management. CNHK300-mE is a selective replication transgene-expressing adenovirus constructed to carry mouse endostatin gene therapeutically. Infection with CNHK300-mE was associated with selective replication of the adenovirus and production of mouse endostatin in telomerase-positive cancer cells. Endostatin secreted from a human gastric cell line, SGC-7901, infected with CNHK300-mE was significantly higher than that infected with nonreplicative adenovirus Ad-mE in vitro (800±94.7 ng/ml versus 132.9±9.9 ng/ml) and in vivo (610±42 ng/ml versus 126 +/- 13 ng/ml). Embryonic chorioallantoic membrane assay showed that the mouse endostatin secreted by CNHK300-mE inhibited angiogenesis efficiently and also induced distortion of pre-existing vasculature. CNHK300-mE exhibited a superior suppression of xenografts in nude mice compared with CNHK300 and Ad-mE. In summary, we provided a more efficient gene-viral therapy strategy by combining oncolysis with antiangiogenesis.

  20. Distribution of TTAGG-specific telomerase activity in insects

    Czech Academy of Sciences Publication Activity Database

    Korandová, M.; Krůček, Tomáš; Vrbová, K.; Čapková Frydrychová, Radmila

    2014-01-01

    Roč. 22, č. 4 (2014), s. 495-503. ISSN 0967-3849 R&D Projects: GA ČR GA14-07172S EU Projects: European Commission(CZ) FP7/2007-2013 Grant ostatní: GA JU(CZ) 05/2013/P Institutional support: RVO:60077344 Keywords : Insects * telomere * telomerase Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.478, year: 2014 http://link.springer.com/article/10.1007%2Fs10577-014-9436-6

  1. Lysine-specific demethylase 1 (LSD1 Is required for the transcriptional repression of the telomerase reverse transcriptase (hTERT gene.

    Directory of Open Access Journals (Sweden)

    Qingjun Zhu

    Full Text Available BACKGROUND: Lysine-specific demethylase 1 (LSD1, catalysing demethylation of mono- and di-methylated histone H3-K4 or K9, exhibits diverse transcriptional activities by mediating chromatin reconfiguration. The telomerase reverse transcriptase (hTERT gene, encoding an essential component for telomerase activity that is involved in cellular immortalization and transformation, is silent in most normal human cells while activated in up to 90% of human cancers. It remains to be defined how exactly the transcriptional activation of the hTERT gene occurs during the oncogenic process. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we determined the effect of LSD1 on hTERT transcription. In normal human fibroblasts with a tight hTERT repression, a pharmacological inhibition of LSD1 led to a weak hTERT expression, and a robust induction of hTERT mRNA was observed when LSD1 and histone deacetylases (HDACs were both inhibited. Small interference RNA-mediated depletion of both LSD1 and CoREST, a co-repressor in HDAC-containing complexes, synergistically activated hTERT transcription. In cancer cells, inhibition of LSD1 activity or knocking-down of its expression led to significant increases in levels of hTERT mRNA and telomerase activity. Chromatin immunoprecipitation assay showed that LSD1 occupied the hTERT proximal promoter, and its depletion resulted in elevated di-methylation of histone H3-K4 accompanied by increased H3 acetylation locally in cancer cells. Moreover, during the differentiation of leukemic HL60 cells, the decreased hTERT expression was accompanied by the LSD1 recruitment to the hTERT promoter. CONCLUSIONS/SIGNIFICANCE: LSD1 represses hTERT transcription via demethylating H3-K4 in normal and cancerous cells, and together with HDACs, participates in the establishment of a stable repression state of the hTERT gene in normal or differentiated malignant cells. The findings contribute to better understandings of hTERT/telomerase

  2. Active Yeast Telomerase Shares Subunits with Ribonucleoproteins RNase P and RNase MRP.

    Science.gov (United States)

    Lemieux, Bruno; Laterreur, Nancy; Perederina, Anna; Noël, Jean-François; Dubois, Marie-Line; Krasilnikov, Andrey S; Wellinger, Raymund J

    2016-05-19

    Telomerase is the ribonucleoprotein enzyme that replenishes telomeric DNA and maintains genome integrity. Minimally, telomerase activity requires a templating RNA and a catalytic protein. Additional proteins are required for activity on telomeres in vivo. Here, we report that the Pop1, Pop6, and Pop7 proteins, known components of RNase P and RNase MRP, bind to yeast telomerase RNA and are essential constituents of the telomerase holoenzyme. Pop1/Pop6/Pop7 binding is specific and involves an RNA domain highly similar to a protein-binding domain in the RNAs of RNase P/MRP. The results also show that Pop1/Pop6/Pop7 function to maintain the essential components Est1 and Est2 on the RNA in vivo. Consistently, addition of Pop1 allows for telomerase activity reconstitution with wild-type telomerase RNA in vitro. Thus, the same chaperoning module has allowed the evolution of functionally and, remarkably, structurally distinct RNPs, telomerase, and RNases P/MRP from unrelated progenitor RNAs. PMID:27156450

  3. TELOMERASE ACTIVITY OF FIBROBRONCHOSCOPIC BRUSHING CELLS IN NON-SMALL CELL LUNG CANCER

    Institute of Scientific and Technical Information of China (English)

    吴晓红; 应可净; 张行

    2003-01-01

    Objective: To evaluate the clinical significance of telomerase activity particularly in terms of prognostic impact in non-small cell lung cancer (NSCLC). Methods: The exfoliated cells from fibrobronchoscopic brushing were studied using polymerase chain reaction based on a telomerase repeat amplification protocal assay. Samples were taken from 60 NSCLC and 20 pulmonary infection cases. Results: Telomerase activity was detected in 53 of 60(88.3%) NSCLC specimens from the lesion side and in 5 of 25(20.0%) from the contralateral side but only in 2 of 20 pulmonary infection samples (P<0.05). The telomerase activity levels in NSCLC (medium 0.109) were significantly higher than those in pulmonary infection (medium 0.018, U=4.95, P<0.05). The telomerase activity levels in tumor staged IIIb-IV (medium 0.173) were higher than those in staged I-IIIa (medium 0.132, U=1.899, P<0.05). Conclusion: Telomerase activity is one of the most important marker in patients with NSCLC. Telomerase activity increases with the advance of tumor stage and can be used as a prognostic indicator of advanced NSCLC.

  4. Lack of telomerase activity in rabbit bone marrow stromal cells during differentiation along neural pathway

    Institute of Scientific and Technical Information of China (English)

    CHEN Zhen-zhou; XU Ru-xiang; JIANG Xiao-dan; TENG Xiao-hua; LI Gui-tao; ZHOU Yü-xi

    2006-01-01

    Objective: To investigate telomerase activity in rabbit bone marrow stromal cells (BMSCs) during their committed differentiation in vitro along neural pathway and the effect of glial cell line-derived neurotrophic factor (GDNF) on the expression of telomerase.Methods: BMSCs were acquired from rabbit marrow and divided into control group, GDNF (10 ng/ml) group.No. ZL02134314. 4) supplemented with 10% fetal bovine serum (FBS) was used to induce BMSCs differentiation along neural pathway. Fluorescent immunocytochemistry was employed to identify the expressions of Nestin, neuronspecific endase (NSE), and gial fibrillary acidic protein (GFAP). The growth curves of the cells and the status of cell cycles were analyzed, respectively. During the differentiation, telomerase activitys were detected using the telomeric repeat amplification protocol-enzyme-linked immunosorbent assay (TRAP-ELISA).Results: BMSCs were successfully induced to differentiate along neural pathway and expressed specific markers of fetal neural epithelium, mature neuron and glial cells. Telomerase activities were undetectable in BMSCs during differentiation along neural pathway. Similar changes of cell growth curves, cell cycle status and telomerase expression were observed in the two groups.Conclusions: Rabbit BMSCs do not display telomerase activity during differentiation along neural pathway. GDNF shows little impact on proliferation and telomerase activity of BMSCs.

  5. Insights into the evolution of mammalian telomerase: Platypus TERT shares similarities with genes of birds and other reptiles and localizes on sex chromosomes

    Directory of Open Access Journals (Sweden)

    Hrdličková Radmila

    2012-06-01

    Full Text Available Abstract Background The TERT gene encodes the catalytic subunit of the telomerase complex and is responsible for maintaining telomere length. Vertebrate telomerase has been studied in eutherian mammals, fish, and the chicken, but less attention has been paid to other vertebrates. The platypus occupies an important evolutionary position, providing unique insight into the evolution of mammalian genes. We report the cloning of a platypus TERT (OanTERT ortholog, and provide a comparison with genes of other vertebrates. Results The OanTERT encodes a protein with a high sequence similarity to marsupial TERT and avian TERT. Like the TERT of sauropsids and marsupials, as well as that of sharks and echinoderms, OanTERT contains extended variable linkers in the N-terminal region suggesting that they were present already in basal vertebrates and lost independently in ray-finned fish and eutherian mammals. Several alternatively spliced OanTERT variants structurally similar to avian TERT variants were identified. Telomerase activity is expressed in all platypus tissues like that of cold-blooded animals and murine rodents. OanTERT was localized on pseudoautosomal regions of sex chromosomes X3/Y2, expanding the homology between human chromosome 5 and platypus sex chromosomes. Synteny analysis suggests that TERT co-localized with sex-linked genes in the last common mammalian ancestor. Interestingly, female platypuses express higher levels of telomerase in heart and liver tissues than do males. Conclusions OanTERT shares many features with TERT of the reptilian outgroup, suggesting that OanTERT represents the ancestral mammalian TERT. Features specific to TERT of eutherian mammals have, therefore, evolved more recently after the divergence of monotremes.

  6. 端粒、端粒酶与肿瘤%Telomere, Telomerase and Tumor

    Institute of Scientific and Technical Information of China (English)

    张岭; 李龙芸

    1999-01-01

    Telomere is the end structure of chromosome and it will be shortened during replication. Telomerase is a reverse transcripatse consisting of both RNA and protein components and synthesizes telomeric DNA by copying the template sequence of its own RNA components to maintain telomere length for function.Telomerase activity in germline cells,immortal and neoplastic cells was detected,but not in mostly normal cells.The telomere-telomerase hypothesis was brung out to explain this phenomenon.According to this hypothesis,re-actived telomerase will maintain telomere's length for protecting chromosome to make the cell immortal.The aging procedure will be explained by this hypothesis too.This hypothesis provides a new concepts of cancer and cancer's treatment.

  7. Effect of Mifepristone on the Telomerase Activity in Chorion and Decidua during Early Pregnancy

    Institute of Scientific and Technical Information of China (English)

    Ge-qing XIA; Ya-li XIONG; Yong-hong SUN

    2004-01-01

    Objective To investigate telomerase activity in chorion and decidua from abortion induced by mifepristone incorporated with misoprostol at early pregnancy Methods TRAP-SYBR Green assay was used to detect the expression of telomerase. Forty specimen were obtained from medicinal abortion (experiment group) and forty were from normal induced abortion (control group).Results Positive expression, of chorion telomerase was significantly different between the experimental group (28%, 11/40) and the control group (73%, 29/40) (P<0. 05).While in decidua, the positive rate was 28% (11/40) in the experimental group and 20% (9/40) in the control group, there was no significant difference (P>0. 05).Conclusion It is suggested that miferistone may significantly decrease the telomerase activity in chorion but not in decidua.

  8. Genetic diagnostic test of hepatocellular carcinoma by telomerase catalytic subunit mRNA.

    Science.gov (United States)

    Wada, E; Hisatomi, H; Moritoyo, T; Kanamaru, T; Hikiji, K

    1998-01-01

    This study investigated the relationship between telomerase activity and telomere length and between telomerase reverse transcriptase (hTERT) mRNA and telomere length. Both cancerous and non-cancerous tissues were studied in individuals with hepatic carcinoma. In this study, the telomere length in HCC livers had a wide range, no clear significant correlation was found between hTERT mRNA and telomere length. Telomerase activity was more strongly correlated with hTERT mRNA than with telomere length. The correlation between hTERT mRNA and telomerase activity shown here indicates that hTERT mRNA has potential for cancer diagnosis. PMID:9769378

  9. Biosensor Techniques Used for Determination of Telomerase Activity in Cancer Cells

    OpenAIRE

    Evgeny Katz; Eliona Kulla

    2008-01-01

    Measuring telomerase activity has proven successful for the determination of cancer in malignant somatic cells. Early conventional methods for the detection of telomerase activity include in vitro analysis via a primer extension assay, and the telomeric repeat amplification protocol (TRAP) assay. TRAP incorporates the polymerase chain reaction (PCR) step to increase the sensitivity of a given sample. However, research suggests that the TRAP technique suffers from false negative results, cause...

  10. The effect of Bortezomib and Rapamycin on Telomerase Activity in Mantle Cell Lymphoma

    Directory of Open Access Journals (Sweden)

    Orit Uziel

    2014-12-01

    In the light of the crucial role of telomerase in cancer cells, it was important to characterize the possible relations between telomerase and bortezomib and to distinguish the biochemical mechanisms of its regulation and its interactions with other signal transduction inhibitors such as rapamycin. The results of this work encourage the in vivo examination of the therapeutic potential of the combination of bortezomib and rapamycin in Mantle Cell Lymphoma patients.

  11. Replication Proteins Influence the Maintenance of Telomere Length and Telomerase Protein Stability

    OpenAIRE

    Dahlén, Maria; Sunnerhagen, Per; Wang, Teresa S.-F.

    2003-01-01

    We investigated the effects of fission yeast replication genes on telomere length maintenance and identified 20 mutant alleles that confer lengthening or shortening of telomeres. The telomere elongation was telomerase dependent in the replication mutants analyzed. Furthermore, the telomerase catalytic subunit, Trt1, and the principal initiation and lagging-strand synthesis DNA polymerase, Polα, were reciprocally coimmunoprecipitated, indicating these proteins physically coexist as a complex i...

  12. Telomerase reverse transcriptase promotes cardiac muscle cell proliferation, hypertrophy, and survival

    OpenAIRE

    Oh, Hidemasa; Taffet, George E.; Youker, Keith A.; Entman, Mark L.; Overbeek, Paul A.; Michael, Lloyd H.; Schneider, Michael D.

    2001-01-01

    Cardiac muscle regeneration after injury is limited by “irreversible” cell cycle exit. Telomere shortening is one postulated basis for replicative senescence, via down-regulation of telomerase reverse transcriptase (TERT); telomere dysfunction also is associated with greater sensitivity to apoptosis. Forced expression of TERT in cardiac muscle in mice was sufficient to rescue telomerase activity and telomere length. Initially, the ventricle was hypercellular, with increased myocyte density an...

  13. NAC selectively inhibit cancer telomerase activity: A higher redox homeostasis threshold exists in cancer cells

    OpenAIRE

    Pengying Li; Meilin Wu; Jing Wang; Yilun Sui; Shanlin Liu; Dongyun Shi

    2016-01-01

    Telomerase activity controls telomere length, and this plays an important role in stem cells, aging and tumors. Antioxidant was shown to protect telomerase activity in normal cells but inhibit that in cancer cells, but the underlying mechanism is elusive. Here we found that 7721 hepatoma cells held a higher redox homeostasis threshold than L02 normal liver cells which caused 7721 cells to have a higher demand for ROS; MnSOD over-expression in 7721 decreased endogenous reactive oxygen species ...

  14. Advantages of assaying telomerase activity in ascites for diagnosis of digestive tract malignancies

    Institute of Scientific and Technical Information of China (English)

    Chung-Pin Li; Tze-Sing Huang; Yee Chao; Full-Young Chang; Jacquline Whang-Peng; Shou-Dong Lee

    2004-01-01

    AIM: To evaluate the diagnostic value of assaying telomerase activity in ascites cells for the differential diagnosis of malignant and non-malignant ascites.METHODS: Ascites from 40 patients with hepatocellular carcinoma (HCC), 31 with non-HCC gastrointestinal carcinoma (CA), and 24 with liver cirrhosis (LC) were analyzed for telomerase activity. The telomerase activities in cell pellets from ascites were measured according to the Telomeric Repeat Amplification Protocol (TRAP) and quantified with a densitometer.RESULTS: Positive telomerase activity was detected in 16 of 31 (52%) CA patients, 10 of 40 (25%) HCC patients, and 1 of 24 (4%) LC patients (P<0.001). The telomerase activity was higher in the ascites of CA patients than in the ascites of HCC or LC patients (CA: 22.9±5.8, HCC: 6.7±2.5, LC:1.3±1.3, P= 0.001). Cytology was positive in 18 CA patients (58%) and 1 HCC patient (2.5%), respectively. The positive telomerase activity was not related to patients' age, gender,and ascitic protein concentration, but to white blood count (r= 0.31, P= 0.002), neutrophil count (r= 0.29, P= 0.005),and the C-reactive protein level (r= 0.29, P= 0.018). When the results of both cytological examination and telomerase assay were considered together, the sensitivity increased to 77% for CA patients, 25% for HCC patients, and 48% for all 71 gastrointestinal cancer patients.CONCLUSION: Combining cytological examination of ascites with telomerase activity assay significantly improves the differential diagnosis between malignant and non-malignant ascites.

  15. Telomerase activity is spontaneously increased in lymphocytes from patients with atopic dermatitis and correlates with cellular proliferation

    DEFF Research Database (Denmark)

    Wu, Kehuai; Volke, Anne Rehné; Lund, Marianne;

    1999-01-01

    Telomerase is a ribonucleoprotein enzyme involved with cellular proliferation and cellular senescence. The aim of the present study was to investigate telomerase activity in lymphocytes from patients with atopic dermatitis (AD) and to observe its regulation of cellular proliferation. Peripheral...... staphylococcal enterotoxin A (SEA) (0.1 microg/ml). Telomerase activity was measured by the telomeric repeat amplification protocol-based telomerase polymerase chain reaction enzyme-linked immunosorbent assay at 0 and 72 h of incubation. In addition, DNA synthesis of the cells was assayed using 3H......-thymidine incorporation. We found that telomerase activity in non-stimulated PBMC from patients with AD was significantly up-regulated without any stimulation during the 72 h of in vitro incubation. The most potent stimulator of telomerase activity was SEA, followed by anti-CD3 plus IL-2, anti-CD3 alone, and PPD. IL-2...

  16. Inhibition of telomerase causes vulnerability to endoplasmic reticulum stress-induced neuronal cell death.

    Science.gov (United States)

    Hosoi, Toru; Nakatsu, Kanako; Shimamoto, Akira; Tahara, Hidetoshi; Ozawa, Koichiro

    2016-08-26

    Endoplasmic reticulum (ER) stress is implicated in several diseases, such as cancer and neurodegenerative diseases. In the present study, we investigated the possible involvement of telomerase in ER stress-induced cell death. ER stress-induced cell death was ameliorated in telomerase reverse transcriptase (TERT) over-expressing MCF7 cells (MCF7-TERT cell). Telomerase specific inhibitor, BIBR1532, reversed the inhibitory effect of TERT on ER stress-induced cell death in MCF7-TERT cells. These findings suggest that BIBR1532 may specifically inhibit telomerase activity, thereby inducing cell death in ER stress-exposed cells. TERT was expressed in the SH-SY5Y neuroblastoma cell line. To analyze the possible involvement of telomerase in ER stress-induced neuronal cell death, we treated SH-SY5Y neuroblastoma cells with BIBR1532 and analyzed ER stress-induced cell death. We found that BIBR1532 significantly enhanced the ER stress-induced neuronal cell death. These findings suggest that inhibition of telomerase activity may enhance vulnerability to neuronal cell death caused by ER stress. PMID:27443785

  17. NMR assignments of the N-terminal domain of Ogataea polymorpha telomerase reverse transcriptase.

    Science.gov (United States)

    Polshakov, Vladimir I; Petrova, Olga A; Parfenova, Yulia Yu; Efimov, Sergey V; Klochkov, Vladimir V; Zvereva, Maria I; Dontsova, Olga A

    2016-04-01

    Telomerase is a ribonucleoprotein enzyme that adds telomeric DNA fragments to the ends of chromosomes. This enzyme is the focus of substantial attention, both because its structure and mechanism of action are still poorly studied, and because of its pivotal roles in aging and cellular proliferation. The use of telomerase as a potential target for the design of new anticancer drugs is also of great interest. The catalytic protein subunit of telomerase (TERT) contains an N-terminal domain (TEN) that is essential for activity and processivity. Elucidation of the structure and dynamics of TEN in solution is important for understanding the molecular mechanism of telomerase activity and for the design of new telomerase inhibitors. To approach this problem, in this study we report the (1)H, (13)C, and (15)N chemical shift assignments of TEN from Ogataea polymorpha. Analysis of the assigned chemical shifts allowed us to identify secondary structures and protein regions potentially involved in interaction with other participants of the telomerase catalytic cycle. PMID:26721464

  18. Direct Single-Stranded DNA Binding by Teb1 Mediates the Recruitment of Tetrahymena thermophila Telomerase to Telomeres

    OpenAIRE

    Upton, Heather E.; Hong, Kyungah; Collins, Kathleen

    2014-01-01

    The eukaryotic reverse transcriptase telomerase copies its internal RNA template to synthesize telomeric DNA repeats at chromosome ends in balance with sequence loss during cell proliferation. Previous work has established several factors involved in telomerase recruitment to telomeres in yeast and mammalian cells; however, it remains unclear what determines the association of telomerase with telomeres in other organisms. Here we investigate the cell cycle dependence of telomere binding by ea...

  19. The Novel Retinoid, 9cUAB30, Inhibits Telomerase and Induces Apoptosis in HL60 Cells1

    OpenAIRE

    LOVE, WILLIAM K.; DeAngelis, J. Tyson; Berletch, Joel B.; Phipps, Sharla MO; Andrews, Lucy G.; Brouillette, Wayne J.; Muccio, Donald D.; Tollefsbol, Trygve O.

    2008-01-01

    Telomerase, a ribonucleoprotein important to neoplastic immortality, is up-regulated in approximately 85% of cancers, including leukemias. In this study, 9cUAB30, a novel retinoic acid, resulted in differentiation of HL60 leukemia cells as indicated by morphologic changes characteristic of granulocytes. It also caused a down-regulation of hTERT gene expression and a decrease in telomerase activity. Telomerase inhibition was followed by loss of proliferative capacity, induction of apoptosis, a...

  20. Irradiation-induced telomerase activity and gastric cancer risk: a case-control analysis in a Chinese Han population

    International Nuclear Information System (INIS)

    Telomerase expression is one of the characteristics of gastric cancer (GC) cells and telomerase activity is frequently up-regulated by a variety of mechanisms during GC development. Therefore, we hypothesized that elevated levels of activated telomerase might enhance GC risk due to increased propagation of cells with DNA damage, such as induced by γ-radiation. To explore this hypothesis, 246 GC cases and 246 matched controls were recruited in our case-control study. TRAP-ELISA was used to assess the levels of telomerase activity at baseline and after γ-radiation and the γ-radiation-induced telomerase activity (defined as after γ-irradiation/baseline) in cultured peripheral blood lymphocytes (PBLs). Our data showed that there was no significant difference for the baseline telomerase activity between GC cases and controls (10.17 ± 7.21 vs. 11.02 ± 8.03, p = 0.168). However, after γ-radiation treatment, γ-radiation-induced telomerase activity was significantly higher in the cases than in the controls (1.51 ± 0.93 vs. 1.22 ± 0.66, p < 0.001). Using the median value of γ-radiation-induced telomerase activity in the controls as a cutoff point, we observed that high γ-radiation-induced telomerase activity was associated with a significantly increased GC risk (adjusted odds ratio, 2.45; 95% confidence interval, 1.83-3.18). Moreover, a dose response association was noted between γ-radiation-induced telomerase activity and GC risk. Age, but not sex, smoking and drinking status seem to have a modulating effect on the γ-radiation-induced telomerase activities in both cases and controls. Overall, our findings for the first time suggest that the increased γ-radiation-induced telomerase activity in PBLs might be associated with elevated GC risk. Further confirmation of this association using a prospective study design is warranted

  1. High telomerase is a hallmark of undifferentiated spermatogonia and is required for maintenance of male germline stem cells.

    Science.gov (United States)

    Pech, Matthew F; Garbuzov, Alina; Hasegawa, Kazuteru; Sukhwani, Meena; Zhang, Ruixuan J; Benayoun, Bérénice A; Brockman, Stephanie A; Lin, Shengda; Brunet, Anne; Orwig, Kyle E; Artandi, Steven E

    2015-12-01

    Telomerase inactivation causes loss of the male germline in worms, fish, and mice, indicating a conserved dependence on telomere maintenance in this cell lineage. Here, using telomerase reverse transcriptase (Tert) reporter mice, we found that very high telomerase expression is a hallmark of undifferentiated spermatogonia, the mitotic population where germline stem cells reside. We exploited these high telomerase levels as a basis for purifying undifferentiated spermatogonia using fluorescence-activated cell sorting. Telomerase levels in undifferentiated spermatogonia and embryonic stem cells are comparable and much greater than in somatic progenitor compartments. Within the germline, we uncovered an unanticipated gradient of telomerase activity that also enables isolation of more mature populations. Transcriptomic comparisons of Tert(High) undifferentiated spermatogonia and Tert(Low) differentiated spermatogonia by RNA sequencing reveals marked differences in cell cycle and key molecular features of each compartment. Transplantation studies show that germline stem cell activity is confined to the Tert(High) cKit(-) population. Telomere shortening in telomerase knockout strains causes depletion of undifferentiated spermatogonia and eventual loss of all germ cells after undifferentiated spermatogonia drop below a critical threshold. These data reveal that high telomerase expression is a fundamental characteristic of germline stem cells, thus explaining the broad dependence on telomerase for germline immortality in metazoans. PMID:26584619

  2. Fluorescence detection of telomerase activity in cancer cell extracts based on autonomous exonuclease III-assisted isothermal cycling signal amplification.

    Science.gov (United States)

    Ding, Caifeng; Li, Xiaoqian; Wang, Wei; Chen, Yaoyao

    2016-09-15

    Based on the extension reaction of a telomerase substrate (TS) primer in the presence of the telomerase, strand-displacement process to perform more stable longer duplex chain, and stepwise hydrolysis of mononucleotides from the blunt or the recessed 3'-hydroxyl termini of duplex DNA in the presence of Exonuclease III (Exo III), an amplified fluorescence detection of telomerase activity in the cancer cells was described in this manuscript. A fluorescence probe DNA, a quencher DNA, and a TS primer were mixed to construct a three-chain DNA structure and a two-chain DNA structure because the amount of the TS primer was less than the other two DNA. In the presence of the telomerase, the quencher DNA was replaced from the probe DNA and the telomerase activity could be determined with the fluorescence enhancement. The telomerase activity in HeLa extracts equivalent to 6-2000 cells was detected by this method. Moreover, the strategy was further proved by using telomerase extracted from Romas cells. With the multiple rounds of isothermal strand displacement and the hydrolysis process, constituted consecutive of signal amplification for the novel detection paradigm that allowed measuring of telomerase activity in crude cancer cell extracts confirmed the reliability and practicality of the protocol, which reveal this platform holds great promise in the biochemical assay for the telomerase activity in early diagnosis for cancers. PMID:27108253

  3. A telomerase em células-tronco hematopoéticas Telomerase in hematopoietic stem cells

    OpenAIRE

    Silvana Perini; Lúcia M. R. Silla; de Andrade, Fabiana M.

    2008-01-01

    A proliferação das células-tronco hematopoéticas sofre a perda dos telômeros a cada divisão celular. Alguns autores discordam quanto à perda ou não do potencial proliferativo e capacidade de auto-renovação das células mais diferenciadas. Revisaremos aqui o papel da telomerase na biologia do sistema hematopoético, na diferenciação normal ou maligna, assim como no envelhecimento das células-tronco hematopoéticas. A constante renovação celular requerida pela hematopoese confere às células-tronco...

  4. Telomerase Reverse Transcriptase and Peroxisome Proliferator-Activated Receptor γ Co-Activator-1α Cooperate to Protect Cells from DNA Damage and Mitochondrial Dysfunction in Vascular Senescence.

    Science.gov (United States)

    Mendelsohn, Andrew R; Larrick, James W

    2015-10-01

    Reduced telomere length with increasing age in dividing cells has been implicated in contributing to the pathologies of human aging, which include cardiovascular and metabolic disorders, through induction of cellular senescence. Telomere shortening results from the absence of telomerase, an enzyme required to maintain telomere length. Telomerase reverse transcriptase (TERT), the protein subunit of telomerase, is expressed only transiently in a subset of adult somatic cells, which include stem cells and smooth muscle cells. A recent report from Xiong and colleagues demonstrates a pivotal role for the transcription co-factor peroxisome proliferator-activated receptor γ co-activator-1α (PGC-1α) in maintaining TERT expression and preventing vascular senescence and atherosclerosis in mice. Ablation of PGC-1α reduced TERT expression and increased DNA damage and reactive oxygen species (ROS), resulting in shortened telomeres and vascular senescence. In the ApoE(-/-) mouse model of atherosclerosis, forced expression of PGC-1α increased expression of TERT, extended telomeres, and reversed genomic DNA damage, vascular senescence, and the development of atherosclerotic plaques. Alpha lipoic acid (ALA) stimulated expression of PGC-1α and TERT and reversed DNA damage, vascular senescence, and atherosclerosis, similarly to ectopic expression of PGC-1α. ALA stimulated cyclic adenosine monophosphate (cAMP) signaling, which in turn activated the cAMP response element-binding protein (CREB), a co-factor for PGC-1α expression. The possibility that ALA might induce TERT to extend telomeres in human cells suggests that ALA may be useful in treating atherosclerosis and other aging-related diseases. However, further investigation is needed to identify whether ALA induces TERT in human cells, which cell types are susceptible, and whether such changes have clinical significance. PMID:26414604

  5. Colorimetry and SERS dual-mode detection of telomerase activity: combining rapid screening with high sensitivity

    Science.gov (United States)

    Zong, Shenfei; Wang, Zhuyuan; Chen, Hui; Hu, Guohua; Liu, Min; Chen, Peng; Cui, Yiping

    2014-01-01

    As an important biomarker and therapeutic target, telomerase has attracted considerable attention concerning its detection and monitoring. Here, we present a colorimetry and surface enhanced Raman scattering (SERS) dual-mode telomerase activity detection method, which has several distinctive advantages. First, colorimetric functionality allows rapid preliminary discrimination of telomerase activity by the naked eye. Second, the employment of SERS technique results in greatly improved detection sensitivity. Third, the combination of colorimetry and SERS into one detection system can ensure highly efficacious and sensitive screening of numerous samples. Besides, the avoidance of polymerase chain reaction (PCR) procedures further guarantees fine reliability and simplicity. Generally, the presented method is realized by an ``elongate and capture'' procedure. To be specific, gold nanoparticles modified with Raman molecules and telomeric repeat complementary oligonucleotide are employed as the colorimetric-SERS bifunctional reporting nanotag, while magnetic nanoparticles functionalized with telomerase substrate oligonucleotide are used as the capturing substrate. Telomerase can synthesize and elongate telomeric repeats onto the capturing substrate. The elongated telomeric repeats subsequently facilitate capturing of the reporting nanotag via hybridization between telomeric repeat and its complementary strand. The captured nanotags can cause a significant difference in the color and SERS intensity of the magnetically separated sediments. Thus both the color and SERS can be used as indicators of the telomerase activity. With fast screening ability and outstanding sensitivity, we anticipate that this method would greatly promote practical application of telomerase-based early-stage cancer diagnosis.As an important biomarker and therapeutic target, telomerase has attracted considerable attention concerning its detection and monitoring. Here, we present a colorimetry and

  6. Telomere length abnormalities and telomerase RNA component expression in gastroenteropancreatic neuroendocrine tumors.

    Science.gov (United States)

    Kim, Hee Sung; Lee, Hye Seung; Nam, Kyung Han; Choi, Jiwoon; Kim, Woo Ho

    2015-06-01

    Telomere lengths in normal human cells are tightly regulated within a narrow range. Telomere length abnormalities are prevalent genetic alterations in malignant transformation. We studied telomere length abnormalities, telomerase RNA component (TERC) expression, alpha-thalassemia X-linked mental retardation (ATRX) expression, and death domain-associated protein (DAXX) expression in gastroenteropancreatic neuroendocrine tumors (GEP-NETs). We used tissue microarrays to perform telomere fluorescent in situ hybridization (FISH) and TERC in situ hybridization in 327 formalin-fixed paraffin-embedded tissues of GEP-NETs. Telomere length abnormalities were detected in 35% of 253 informative cases by using telomere FISH. Ten cases had altered lengthening of telomeres (ALT), an ALT-positive phenotype (4%), and 79 cases had telomere shortening (31%). The ALT-positive phenotype was significantly associated with tumors of pancreatic origin (7/10) and loss of ATRX or DAXX protein (8/10). Telomere shortening was significantly associated with low TERC expression. In the survival analysis, loss of ATRX or DAXX protein was associated with a decreased overall survival. Multivariate regression analysis showed that lymph node metastasis and high TERC expression were independent prognostic factors of reduced overall survival (OS) for patients with GEP-NETs. Our results showed that telomere lengthening (the ALT-positive phenotype) and telomere shortening accompanied by low TERC levels are two types of clinically significant telomere abnormalities in GEP-NETs. PMID:26026117

  7. New therapeutic approach for brain tumors: Intranasal delivery of telomerase inhibitor GRN163.

    Science.gov (United States)

    Hashizume, Rintaro; Ozawa, Tomoko; Gryaznov, Sergei M; Bollen, Andrew W; Lamborn, Kathleen R; Frey, William H; Deen, Dennis F

    2008-04-01

    The blood-brain barrier is a substantial obstacle for delivering anticancer agents to brain tumors, and new strategies for bypassing it are greatly needed for brain-tumor therapy. Intranasal delivery provides a practical, noninvasive method for delivering therapeutic agents to the brain and could provide an alternative to intravenous injection and convection-enhanced delivery. We treated rats bearing intracerebral human tumor xenografts intranasally with GRN163, an oligonucleotide N3'-->P5'thio-phosphoramidate telomerase inhibitor. 3'-Fuorescein isothiocyanate (FITC)-labeled GRN163 was administered intranasally every 2 min as 6 microl drops into alternating sides of the nasal cavity over 22 min. FITC-labeled GRN163 was present in tumor cells at all time points studied, and accumulation of GRN163 peaked at 4 h after delivery. Moreover, GRN163 delivered intranasally, daily for 12 days, significantly prolonged the median survival from 35 days in the control group to 75.5 days in the GRN163-treated group. Thus, intranasal delivery of GRN163 readily bypassed the blood-brain barrier, exhibited favorable tumor uptake, and inhibited tumor growth, leading to a prolonged lifespan for treated rats compared to controls. This delivery approach appears to kill tumor cells selectively, and no toxic effects were noted in normal brain tissue. These data support further development of intranasal delivery of tumor-specific therapeutic agents for brain tumor patients. PMID:18287341

  8. The TPR-containing domain within Est1 homologs exhibits species-specific roles in telomerase interaction and telomere length homeostasis

    Directory of Open Access Journals (Sweden)

    LeBel Catherine

    2011-10-01

    Full Text Available Abstract Background The first telomerase-associated protein (Est1 was isolated in yeast due to its essential role in telomere maintenance. The human counterparts EST1A, EST1B, and EST1C perform diverse functions in nonsense-mediated mRNA decay (NMD, telomere length homeostasis, and telomere transcription. Although Est1 and EST1A/B interact with the catalytic subunit of yeast and human telomerase (Est2 and TERT, respectively, the molecular determinants of these interactions have not been elaborated fully. Results To investigate the functional conservation of the EST1 protein family, we performed protein-protein interaction mapping and structure-function analysis. The domain in hEST1A most conserved between species, containing a TPR (tricotetrapeptide repeat, was sufficient for interaction of hEST1A with multiple fragments of hTERT including the N-terminus. Two mutations within the hTERT N-terminus that perturb in vivo function (NAAIRS92, NAAIRS122 did not affect this protein interaction. ScEst1 hybrids containing the TPR of hEST1A, hEST1B, or hEST1C were expressed in yeast strains lacking EST1, yet they failed to complement senescence. Point mutations within and outside the cognate ScEst1 TPR, chosen to disrupt a putative protein interaction surface, resulted in telomere lengthening or shortening without affecting recruitment to telomeres. Conclusions These results identify a domain encompassing the TPR of hEST1A as an hTERT interaction module. The TPR of S. cerevisiae Est1 is required for telomerase-mediated telomere length maintenance in a manner that appears separable from telomere recruitment. Discrete residues in or adjacent to the TPR of Est1 also regulate telomere length homeostasis.

  9. Telomerase regulates MYC-driven oncogenesis independent of its reverse transcriptase activity.

    Science.gov (United States)

    Koh, Cheryl M; Khattar, Ekta; Leow, Shi Chi; Liu, Chia Yi; Muller, Julius; Ang, Wei Xia; Li, Yinghui; Franzoso, Guido; Li, Shang; Guccione, Ernesto; Tergaonkar, Vinay

    2015-05-01

    Constitutively active MYC and reactivated telomerase often coexist in cancers. While reactivation of telomerase is thought to be essential for replicative immortality, MYC, in conjunction with cofactors, confers several growth advantages to cancer cells. It is known that the reactivation of TERT, the catalytic subunit of telomerase, is limiting for reconstituting telomerase activity in tumors. However, while reactivation of TERT has been functionally linked to the acquisition of several "hallmarks of cancer" in tumors, the molecular mechanisms by which this occurs and whether these mechanisms are distinct from the role of telomerase on telomeres is not clear. Here, we demonstrated that first-generation TERT-null mice, unlike Terc-null mice, show delayed onset of MYC-induced lymphomagenesis. We further determined that TERT is a regulator of MYC stability in cancer. TERT stabilized MYC levels on chromatin, contributing to either activation or repression of its target genes. TERT regulated MYC ubiquitination and proteasomal degradation, and this effect of TERT was independent of its reverse transcriptase activity and role in telomere elongation. Based on these data, we conclude that reactivation of TERT, a direct transcriptional MYC target in tumors, provides a feed-forward mechanism to potentiate MYC-dependent oncogenesis. PMID:25893605

  10. Effect of VEGF, P53 and telomerase on angiogenesis of gastric carcinoma tissue

    Institute of Scientific and Technical Information of China (English)

    Yan-Fang Yu; Yong Zhang; Na Shen; Rui-Ying Zhang; Xin-Qing Lu

    2014-01-01

    Objective: To investigate the effect of vascular endothelial growth factor (VEGF), P53 and telomerase on angiogenesis in gastric carcinoma tissue. Methods: A total of 95 surgical resection samples of gastric cancer tissue after pathological diagnosis are collected to observe the VEGF, P53 and telomerase expression using immunohistochemical methods. Relationship between their expression and its influence on angiogenesis in gastric carcinoma tissue were analyzed. Results:Microvascular density (MVD) and the expression of VEGF, P53 and telomerase were positively correlated. Expression of VEGF and P53 protein were related to tumor type and lymph metastasis, and also a correlation was observed between P53 and VEGF. The telomerase expression had no correlation with VEGF, and P53. Conclusions: VEGF angiogenesis has a angiogenesis promoting effect on gastric cancer tissue development and plays an important role in tumor generation and metastasis. Mutant P53 promotes the tumor angiogenesis generation by adjusting VEGF. Telomerase has a certain role in promoting activity of angiogenesis through different way rather than P53.

  11. Comparison of telomerase activity in prostate cancer, prostatic intraepithelial neoplasia and benign prostatic hyperplasia

    Directory of Open Access Journals (Sweden)

    Soleiman Mahjoub

    2006-11-01

    Full Text Available BACKGROUND: Telomerase is a reverse transcriptase enzyme that synthesizes telomeric DNA on chromosome ends. The enzyme is important for the immortalization of cancer cells because it maintains the telomeres. METHODS: Telomerase activity (TA was measured by fluorescence-based telomeric repeat amplification protocol (FTRAP assay in prostate carcinoma and benign prostatic hyperplasia (BPH. RESULTS: TA was present in 91.4% of 70 prostate cancers, 68.8% of 16 prostatic intraepithelial neoplasia (PIN, 43.3% of 30 BPH*, 21.4% of 14 atrophy and 20% of 15 normal samples adjacent to tumor. There was not any significant correlation between TA, histopathological tumor stage or gleason score. In contrast to high TA in the BPH* tissue from the cancer-bearing gland, only 6.3% of 32 BPH specimens from patients only diagnosed with BPH were telomerase activity-positive. CONCLUSIONS: These results indicate that TA is present in most prostate cancers. The high rate of TA in tissue adjacent to tumor may be attributed either to early molecular alteration of cancer that was histologically unapparent, or to the presence of occult cancer cells. Our findings suggest that the re-expression of telomerase activity could be one step in the transformation of BPH to PIN. KEY WORDS: Telomerase activity, prostate cancer, prostatic intraepithelial neoplasia, benign prostatic hyperplasia.

  12. Effects of Curcuma longa Extract on Telomerase Activity in Lung and Breast Cancer Cells

    Directory of Open Access Journals (Sweden)

    Nosratollah Zarghami

    2014-10-01

    Full Text Available Background: The purpose of this study is to evaluate the effect of Curcuma longa extract on the telomerase gene expression in QU-DB lung cancer and T47D breast cancer cell lines. Materials and Methods: The present study is an experimental research. Using 3 different phases n-hexane, dichloromethane and methanol, total extract of Curcuma longa in a serial dilution was prepared and three phases was analyzed for determining which phase has more curcuminoids. Then the extract cytotoxicity effect was tested on breast cancer cell line (T47D, and lung cancer cell line (QU-DB by 24, 48 and 72 h MTT (Dimethyl thiazolyl diphenyl tetrazolium assay. Then, the cells were treated with serial concentrations of the extract. Finally, total protein was extracted from the control and test groups, its quantity was determined and telomeric repeat amplification protocol (TRAP assay was performed for measurement of possible inhibition of the telomerase activity. Results: Cell viability and MTT-based cytotoxicity assay show that the total extract of Curcuma longa has cytotoxic effect with different IC50s in breast and lung cancer cell lines. Analysis of TRAP assay also shows a significant reduction in telomerase activity on both cancer cells with different levels. Conclusion: Curcuma longa extract has anti-proliferation and telomerase inhibitory effects on QU-DB lung cancer and T47D breast cancer cells with differences in levels of telomerase inhibition.

  13. The effects of erythropoietin signaling on telomerase regulation in non-erythroid malignant and non-malignant cells

    International Nuclear Information System (INIS)

    Highlights: • We assumed that some of erythropoietin adverse effects may be mediated by telomerase activity. • EPO administration increased telomerase activity, cells proliferation and migration. • The inhibition of telomerase modestly repressed the proliferative effect of erythropoietin. • Telomere shortening caused by long term inhibition of the enzyme totally abolished that effect. • This effect was mediated via the Lyn–AKT axis and not by the canonical JAK2–STAT pathway. - Abstract: Treatment with erythropoietin (EPO) in several cancers is associated with decreased survival due to cancer progression. Due to the major importance of telomerase in cancer biology we hypothesized that some of these effects may be mediated through EPO effect on telomerase. For this aim we explored the possible effects of EPO on telomerase regulation, cell migration and chemosensitivity in non-erythroid malignant and non-malignant cells. Cell proliferation, telomerase activity (TA) and cell migration increased in response to EPO. EPO had no effect on cancer cells sensitivity to cisplatinum and on the cell cycle status. The inhibition of telomerase modestly repressed the proliferative effect of EPO. Telomere shortening caused by long term inhibition of the enzyme abolished the effect of EPO, suggesting that EPO effects on cancer cells are related to telomere dynamics. TA was correlated with the levels of Epo-R. The increase in TA was mediated post-translationally through the Lyn-Src and not the canonical JAK2 pathway

  14. Telomerase in relation to expression of p53, c-Myc and estrogen receptor in ovarian tumours

    NARCIS (Netherlands)

    Wisman, GBA; Hollema, H; Helder, MN; Knol, AJ; Van Der Meer, GT; Krans, M; De Jong, S; De Vries, EGE; Van Der Zee, AGJ

    2003-01-01

    Telomerase activity and its subunits (hTERC, hTERT mRNA) were evaluated in ovarian tumours in relation to the expression of p53, c-Myc and estrogen receptor (ER). Furthermore, relations between telomerase activity, hTERC and hTERT with known clinicopathologic prognostic factors and survival in patie

  15. The effects of erythropoietin signaling on telomerase regulation in non-erythroid malignant and non-malignant cells

    Energy Technology Data Exchange (ETDEWEB)

    Uziel, Orit, E-mail: Oritu@clalit.org.il [Felsenstein Medical Research Center, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv (Israel); Kanfer, Gil [Felsenstein Medical Research Center, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv (Israel); Dep. of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv (Israel); Beery, Einat [Felsenstein Medical Research Center, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv (Israel); Yelin, Dana; Shepshelovich, Daniel [Medicine A, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv (Israel); Bakhanashvili, Mary [Unit of Infectious Diseases, Sheba Medical Center, Tel-Hashomer (Israel); Nordenberg, Jardena [Felsenstein Medical Research Center, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv (Israel); Dep. of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv (Israel); Endocrinology Laboratory, Beilinson Medical Center, Petah-Tikva (Israel); Lahav, Meir [Felsenstein Medical Research Center, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv (Israel); Medicine A, Sackler School of Medicine, Tel-Aviv University, Ramat-Aviv (Israel)

    2014-07-18

    Highlights: • We assumed that some of erythropoietin adverse effects may be mediated by telomerase activity. • EPO administration increased telomerase activity, cells proliferation and migration. • The inhibition of telomerase modestly repressed the proliferative effect of erythropoietin. • Telomere shortening caused by long term inhibition of the enzyme totally abolished that effect. • This effect was mediated via the Lyn–AKT axis and not by the canonical JAK2–STAT pathway. - Abstract: Treatment with erythropoietin (EPO) in several cancers is associated with decreased survival due to cancer progression. Due to the major importance of telomerase in cancer biology we hypothesized that some of these effects may be mediated through EPO effect on telomerase. For this aim we explored the possible effects of EPO on telomerase regulation, cell migration and chemosensitivity in non-erythroid malignant and non-malignant cells. Cell proliferation, telomerase activity (TA) and cell migration increased in response to EPO. EPO had no effect on cancer cells sensitivity to cisplatinum and on the cell cycle status. The inhibition of telomerase modestly repressed the proliferative effect of EPO. Telomere shortening caused by long term inhibition of the enzyme abolished the effect of EPO, suggesting that EPO effects on cancer cells are related to telomere dynamics. TA was correlated with the levels of Epo-R. The increase in TA was mediated post-translationally through the Lyn-Src and not the canonical JAK2 pathway.

  16. Telomerase activity in high-grade cervical lesions is associated with allelic imbalance at 6Q14-22.

    NARCIS (Netherlands)

    Duin, van M.; Steenbergen, R.D.M.; Wilde, de J.; Helmerhorst, TJ; Verheijen, R.H.M.; Risse, E.K.J.; Meijer, C.J.L.M.; Snijders, P.J.F.

    2003-01-01

    Our study attempts to establish the relationship between telomerase activity and allelic imbalance (AI) on chromosomes 3p and 6 in high-risk HPV-containing cervical lesions. These chromosomes were implicated previously in telomerase regulation in HPV containing immortalized cells and cervical cancer

  17. CLINICAL SIGNIFICANCE OF TELOMERASE ACTIVITY AND PERIPHERAL VENOUS BLOOD CK-20 EXPRESSION IN BLADDER TRANSITIONAL CELL CARCINOMA

    Institute of Scientific and Technical Information of China (English)

    钟惟德; 曾广翘; 蔡岳斌; 胡建波; 魏鸿蔼

    2003-01-01

    Objective: The relationship between peripheral blood CK-20 Mrna expression and tissue telomerase activity in bladder transitional cell carcinoma (TCCB) was investigated to evaluate the feasibility of their combined detection in early-stage diagnosis and prognosis estimation of TCCB. Methods: the blood CK-20 was detected by semi-nested RT-PCR and telomerase activity in tumor tissue was examined with silver-stained TRAP reaction. Results: the blood CK-20 expression and tissue telomerase activity in TCCB were 41% and 93% respectively. No statistical significance was detected among pathological grading and clinical staging (P>0.05). Positive correlation was shown between CK-20 expression and telomerase activity with the pathologic grade or clinical stage. Conclusion: combined use of blood CK-20 and tissue telomerase activity detections might be of great importance for clinical diagnosis, treatment and prognosis evaluation.

  18. Telomere and telomerase in chronic liver disease and hepatocarcinoma.

    Science.gov (United States)

    Carulli, Lucia; Anzivino, Claudia

    2014-05-28

    The pathogenesis of liver cirrhosis is not completely elucidated. Although in the majority of patients, the risk factors may be identified in B and C viral hepatitis, alcohol intake, drugs or fatty liver disease, there is a small percentage of patients with no apparent risk factors. In addition, the evolution of chronic liver disease is highly heterogeneous from one patient to another. Among patient with identical risk factors, some rapidly progress to cirrhosis and hepatocellular carcinoma (HCC) whereas others have a benign course. Therefore, a genetic predisposition may contribute to the development of cirrhosis and HCC. Evidence supporting the role of genetic factors as a risk for cirrhosis has been accumulating during the past years. In addition to the results from epidemiological studies, polymorphisms studies and data on twins, the concept of telomere shortening as a genetic risk factor for chronic liver disease and HCC has been proposed. Here we review the literature on telomerase mutations, telomere shortening and liver disease including hepatocellular carcinoma. PMID:24876749

  19. A non-canonical function of telomerase RNA in the regulation of developmental myelopoiesis in zebrafish

    Science.gov (United States)

    Alcaraz-Pérez, Francisca; García-Castillo, Jesús; García-Moreno, Diana; López-Muñoz, Azucena; Anchelin, Monique; Angosto, Diego; Zon, Leonard I.; Mulero, Victoriano; Cayuela, María L.

    2014-02-01

    Dyskeratosis congenita (DC) is an inherited disorder with mutations affecting telomerase or telomeric proteins. DC patients usually die of bone marrow failure. Here we show that genetic depletion of the telomerase RNA component (TR) in the zebrafish results in impaired myelopoiesis, despite normal development of haematopoietic stem cells (HSCs). The neutropenia caused by TR depletion is independent of telomere length and telomerase activity. Genetic analysis shows that TR modulates the myeloid-erythroid fate decision by controlling the levels of the master myeloid and erythroid transcription factors spi1 and gata1, respectively. The alteration in spi1 and gata1 levels occurs through stimulation of gcsf and mcsf. Our model of TR deficiency in the zebrafish illuminates the non-canonical roles of TR, and could establish therapeutic targets for DC.

  20. [Clinical significance of telomerase activity in precancerous lesion of the liver (adenomatous hyperplasia)].

    Science.gov (United States)

    Nishimoto, A; Miura, N; Oshimura, M

    1998-05-01

    To understand the role of telomere dynamics in hepatocellular carcinogenesis, we examined the lengths of terminal restriction fragments (TRFs) in hepatocellular carcinoma (HCC) and surrounding tissues with chronic active hepatitis (CAH), liver cirrhosis (LC) and atypical adenomatous hyperplasia (AAH). The peak TRFs in all HCCs were significantly shorter than those of the surrounding tissues (CAH, LC). TRF in AAH was shortened and similar to that of HCC. Telomerase was examined in CAH, LC, AH, and HCC, and detected in high levels almost exclusively in HCCs. Interestingly, the intensity of telomerase activity in the AH was similar to that of HCC. Thus, the progressive shortening of telomere and the activation of telomerase may be a useful marker for the early detection of malignant progression in liver disease. PMID:9613131

  1. Role of Mitochondrial Translocation of Telomerase in Hepatocellular Carcinoma Cells with Multidrug Resistance

    Directory of Open Access Journals (Sweden)

    Xianlong Ling, Lei Wen, Yuan Zhou

    2012-01-01

    Full Text Available Multidrug resistance (MDR is a major obstacle of cancer chemotherapy. This study aimed to investigate the role of mitochondrial translocation of telomerase (hTERT in MDR of human hepatocellular carcinoma (HCC cells. In this study, three HCC cell lines (SK-Hep1/CDDP1 cells, SK-Hep1/CDDP2 cells and SK-Hep1/CDDP3 cells with differential resistance index (RI to cisplatin (CDDP were induced by pulse treatment of SK-Hep1 (human hepatocellular cell line with CDDP in vitro. The RI of SK-Hep1/CDDP1 cells, SK-Hep1/CDDP2 cells and SK-Hep1/CDDP3 cells was 5.14, 8.66, and 14.25, respectively, and all the cell lines showed cross-resistance to Doxorubicin (DOX and 5-Fuorouracil (5-FU. The apoptosis rates in drug-resistant cells were significantly reduced. Cell cycle analysis revealed the ratio of drug-resistant cells in G2/M and S phases increased, while that in G1 phase decreased. Immunofluorescence staining and Western blot assay demonstrated, with the gradual elevation in RI, increasing hTERT translocated from the nuclei to the mitochondria, while real-time PCR indicated the shortening of telomere length in drug-resistant cells under the chemotherapeutic stress and the reduction of damaged mtDNA with the increase in RI. Furthermore, JC-1 staining also indicated the reduction of mitochondrial membrane potential in drug-resistant cells. The mitochondrial translocation of hTERT increases in multidrug-resistant cells and exerts protective effect on mitochondrial function. Drug-resistant tumor cells escape from apoptosis through hTERT-mediated mitochondrial protection. Mitochondrial translocation of hTERT may serve as an underlying mechanism of MDR.

  2. Role of mitochondrial translocation of telomerase in hepatocellular carcinoma cells with multidrug resistance.

    Science.gov (United States)

    Ling, Xianlong; Wen, Lei; Zhou, Yuan

    2012-01-01

    Multidrug resistance (MDR) is a major obstacle of cancer chemotherapy. This study aimed to investigate the role of mitochondrial translocation of telomerase (hTERT) in MDR of human hepatocellular carcinoma (HCC) cells. In this study, three HCC cell lines (SK-Hep1/CDDP1 cells, SK-Hep1/CDDP2 cells and SK-Hep1/CDDP3 cells) with differential resistance index (RI) to cisplatin (CDDP) were induced by pulse treatment of SK-Hep1 (human hepatocellular cell line) with CDDP in vitro. The RI of SK-Hep1/CDDP1 cells, SK-Hep1/CDDP2 cells and SK-Hep1/CDDP3 cells was 5.14, 8.66, and 14.25, respectively, and all the cell lines showed cross-resistance to Doxorubicin (DOX) and 5-Fuorouracil (5-FU). The apoptosis rates in drug-resistant cells were significantly reduced. Cell cycle analysis revealed the ratio of drug-resistant cells in G2/M and S phases increased, while that in G1 phase decreased. Immunofluorescence staining and Western blot assay demonstrated, with the gradual elevation in RI, increasing hTERT translocated from the nuclei to the mitochondria, while real-time PCR indicated the shortening of telomere length in drug-resistant cells under the chemotherapeutic stress and the reduction of damaged mtDNA with the increase in RI. Furthermore, JC-1 staining also indicated the reduction of mitochondrial membrane potential in drug-resistant cells. The mitochondrial translocation of hTERT increases in multidrug-resistant cells and exerts protective effect on mitochondrial function. Drug-resistant tumor cells escape from apoptosis through hTERT-mediated mitochondrial protection. Mitochondrial translocation of hTERT may serve as an underlying mechanism of MDR. PMID:22991493

  3. Modulation of telomerase activity in fish muscle by biological and environmental factors.

    Science.gov (United States)

    Peterson, Drew Ryan; Mok, Helen Oi Lam; Au, Doris Wai Ting

    2015-12-01

    Telomerase expression has long been linked to promotion of tumor growth and cell proliferation in mammals. Interestingly, telomerase activity (TA) has been detected in skeletal muscle for a variety of fish species. Despite this being a unique feature in fish, very few studies have investigated the potential role of TA in muscle. The present study was set to prove the concepts that muscle telomerase in fish is related to body growth, and more specifically, to muscle cell proliferation and apoptosis in vivo. Moreover, muscle TA can be influenced by biotic factors and modulated by environmental stress. Using three fish species, mangrove red snapper (Lutjanus argentimaculatus), orange-spotted grouper (Epinephelus coioides), and marine medaka (Oryzias melastigma), the present work reports for the first time that fish muscle TA was sensitive to the environmental stresses of starvation, foodborne exposure to benzo[a]pyrene, and hypoxia. In marine medaka, muscle TA was coupled with fish growth during early life stages. Upon sexual maturation, muscle TA was confounded by sex (female>male). Muscle TA was significantly correlated with telomerase reverse transcriptase (TERT) protein expression (Pearson correlation r=0.892; p≤0.05), which was coupled with proliferating cell nuclear antigen (PCNA) cell proliferation, but not associated with apoptosis (omBax/omBcl2 ratio) in muscle tissue. The results reported here have bridged the knowledge gap between the existence and function of telomerase in fish muscle. The underlying regulatory mechanisms of muscle TA in fish warrant further exploration for comparison with telomerase regulation in mammals. PMID:26400776

  4. Increased fibroblast telomerase expression precedes myofibroblast α-smooth muscle actin expression in idiopathic pulmonary fibrosis

    Directory of Open Access Journals (Sweden)

    Daniel Reis Waisberg

    2012-09-01

    Full Text Available OBJECTIVE: This study sought to identify the relationship between fibroblast telomerase expression, myofibroblasts, and telomerase-mediated regulatory signals in idiopathic pulmonary fibrosis. METHODS: Thirty-four surgical lung biopsies, which had been obtained from patients with idiopathic pulmonary fibrosis and histologically classified as usual interstitial pneumonia, were examined. Immunohistochemistry was used to evaluate fibroblast telomerase expression, myofibroblast α-smooth muscle actin expression and the tissue expression of inter leu kin-4, transforming growth factor-β, and basic fibroblast growth factor. The point-counting technique was used to quantify the expression of these markers in unaffected, collapsed, mural fibrosis, and honeycombing areas. The results were correlated to patient survival. RESULTS: Fibroblast telomerase expression and basic fibroblast growth factor tissue expression were higher in collapsed areas, whereas myofibroblast expression and interleukine-4 tissue expression were higher in areas of mural fibrosis. Transforming growth factor-β expression was higher in collapsed, mural fibrosis and honeycombing areas in comparison to unaffected areas. Positive correlations were found between basic fibroblast growth factor tissue expression and fibroblast telomerase expression and between interleukin-4 tissue expression and myofibroblast α-smooth muscle actin expression. Negative correlations were observed between interleukin-4 expression and basic fibroblast growth factor tissue expression in areas of mural fibrosis. Myofibroblast α-smooth muscle actin expression and interleukin-4 tissue expression in areas of mural fibrosis were negatively associated with patient survival. CONCLUSION: Fibroblast telomerase expression is higher in areas of early remodeling in lung tissues demonstrating typical interstitial pneumonia, whereas myofibroblast α-smooth muscle actin expression predominates in areas of late remodeling

  5. The TROVE module: A common element in Telomerase, Ro and Vault ribonucleoproteins

    OpenAIRE

    Bateman Alex; Kickhoefer Valerie

    2003-01-01

    Abstract Background Ribonucleoproteins carry out a variety of important tasks in the cell. In this study we show that a number of these contain a novel module, that we speculate mediates RNA-binding. Results The TROVE module – Telomerase, Ro and Vault module – is found in TEP1 and Ro60 the protein components of three ribonucleoprotein particles. This novel module, consisting of one or more domains, may be involved in binding the RNA components of the three RNPs, which are telomerase RNA, Y RN...

  6. Effects of Telomerase and Telomere Length on Epidermal Stem Cell Behavior

    Science.gov (United States)

    Flores, Ignacio; Cayuela, María L.; Blasco, María A.

    2005-08-01

    A key process in organ homeostasis is the mobilization of stem cells out of their niches. We show through analysis of mouse models that telomere length, as well as the catalytic component of telomerase, Tert, are critical determinants in the mobilization of epidermal stem cells. Telomere shortening inhibited mobilization of stem cells out of their niche, impaired hair growth, and resulted in suppression of stem cell proliferative capacity in vitro. In contrast, Tert overexpression in the absence of changes in telomere length promoted stem cell mobilization, hair growth, and stem cell proliferation in vitro. The effects of telomeres and telomerase on stem cell biology anticipate their role in cancer and aging.

  7. Telomere Cap Components Influence the Rate of Senescence in Telomerase-Deficient Yeast Cells

    OpenAIRE

    Enomoto, Shinichiro; Glowczewski, Lynn; Lew-Smith, Jodi; Berman, Judith G.

    2004-01-01

    Cells lacking telomerase undergo senescence, a progressive reduction in cell division that involves a cell cycle delay and culminates in “crisis,” a period when most cells become inviable. In telomerase-deficient Saccharomyces cerevisiae cells lacking components of the nonsense-mediated mRNA decay (NMD) pathway (Upf1,Upf2, or Upf3 proteins), senescence is delayed, with crisis occurring ∼10 to 25 population doublings later than in Upf+ cells. Delayed senescence is seen in upfΔ cells lacking th...

  8. Coordinate increase of telomerase activity and c-Myc expression in Helicobacter pylori-associated gastric diseases

    Institute of Scientific and Technical Information of China (English)

    Guo-Xin Zhang; Yan-Hong Gu; Zhi-Quan Zhao; Shun-Fu Xu; Hong-Ji Zhang; Hong-Di Wang; Bo Hao

    2004-01-01

    AIM: To detect the telomerase activity and c-Myc expression in gastric diseases and to examine the relation between these values and Helicobacter pylori (H pylori) as a risk factor for gastric cancer.METHODS: One hundred and seventy-one gastric samples were studied to detect telomerase activity using a telomerase polymerase chain reaction enzyme linked immunosorbent assay (PCR-ELTSA), and c-Myc expression using immunohistochemistry.RESULTS: The telomerase activity and c-Myc expression were higher in cancers (87.69% and 61.54%) than in noncancerous tissues. They were higher in chronic atrophic gastritis with severe intestinal metaplasia (52.38% and 47.62%) than in chronic atrophic gastritis with mild intestinal metaplasia (13.33% and 16.67%). Tn chronic atrophic gastritis with severe intestinal metaplasia, the telomerase activity and c-Myc expression were higher in cases with -H pylori infection (67.86% and 67.86%) than in those without infection (21.43%and 7.14%). c-Myc expression was higher in gastric cancer with H pylori infection (77.27%) than in that without infection (28.57%). The telomerase activity and c-Nyc expression were coordinately up-regulated in H pylori infected gastric cancer and chronic atrophic gastritis with severe intestinal metaplasia.CONCLUSION: H pylori infection may influence both telomerase activity and c-Myc expression in gastric diseases,especially in chronic atrophic gastritis.

  9. Glucose restriction decreases telomerase activity and enhances its inhibitor response on breast cancer cells: possible extra-telomerase role of BIBR 1532

    OpenAIRE

    Wardi, Layal; Alaaeddine, Nada; Raad, Issam; Sarkis, Riad; Serhal, Rim; Khalil, Charbel; Hilal, George

    2014-01-01

    Background Considerable progress has been made to understand the association between lifestyle and diet in cancer initiation and promotion. Because excessive glucose consumption is a key metabolic hallmark of cancer cells, glucose restriction (GR) decreases the proliferation, and promotes the differentiation and transformation of cancer cells to quiescent cells. The immortality of cancerous cells is largely assured by telomerase, which is an interesting target for inhibition by BIBR 1532. In ...

  10. Vault Poly(ADP-Ribose) Polymerase Is Associated with Mammalian Telomerase and Is Dispensable for Telomerase Function and Vault Structure In Vivo

    OpenAIRE

    Liu, Yie; Snow, Bryan E.; Kickhoefer, Valerie A; Erdmann, Natalie; Zhou, Wen; Wakeham, Andrew; Gomez, Marla; Rome, Leonard H.; Harrington, Lea

    2004-01-01

    Vault poly(ADP-ribose) polymerase (VPARP) was originally identified as a minor protein component of the vault ribonucleoprotein particle, which may be involved in molecular assembly or subcellular transport. In addition to the association of VPARP with the cytoplasmic vault particle, subpopulations of VPARP localize to the nucleus and the mitotic spindle, indicating that VPARP may have other cellular functions. We found that VPARP was associated with telomerase activity and interacted with ex...

  11. Stable expression of promyelocytic leukaemia (PML protein in telomerase positive MCF7 cells results in alternative lengthening of telomeres phenotype

    Directory of Open Access Journals (Sweden)

    Yong Jacklyn W Y

    2012-08-01

    Full Text Available Abstract Background Cancer cells can employ telomerase or the alternative lengthening of telomeres (ALT pathway for telomere maintenance. Cancer cells that use the ALT pathway exhibit distinct phenotypes such as heterogeneous telomeres and specialised Promyelocytic leukaemia (PML nuclear foci called APBs. In our study, we used wild-type PML and a PML mutant, in which the coiled-coil domain is deleted (PML C/C-, to investigate how these proteins can affect telomere maintenance pathways in cancer cells that use either the telomerase or ALT pathway. Results Stable over-expression of both types of PML does not affect the telomere maintenance in the ALT cells. We report novel observations in PML over-expressed telomerase-positive MCF7 cells: 1 APBs are detected in telomerase-positive MCF7 cells following over-expression of wild-type PML and 2 rapid telomere elongation is observed in MCF7 cells that stably express either wild-type PML or PML C/C-. We also show that the telomerase activity in MCF7 cells can be affected depending on the type of PML protein over-expressed. Conclusion Our data suggests that APBs might not be essential for the ALT pathway as MCF7 cells that do not contain APBs exhibit long telomeres. We propose that wild-type PML can either definitively dominate over telomerase or enhance the activity of telomerase, and PML C/C- can allow for the co-existence of both telomerase and ALT pathways. Our findings add another dimension in the study of telomere maintenance as the expression of PML alone (wild-type or otherwise is able to change the dynamics of the telomerase pathway.

  12. Detection of K-ras point mutation and telomerase activity during endoscopic retrograde cholangiopancreatography in diagnosis of pancreatic cancer

    Institute of Scientific and Technical Information of China (English)

    Guo-Xiong Zhou; Jie-Fei Huang; Zhao-Shen Li; Guo-Ming Xu; Feng Liu; Hong Zhang

    2004-01-01

    AIM: To study the value of monitoring K-ras point mutation at codon 12 and telomerase activity in exfoliated cells obtained from pancreatic duct brushings during endoscopic retrograde cholangiopancreatography (ERCP) in the diagnosis of pancreatic cancer.METHODS: Exfoliated cells obtained from pancreatic duct brushings during ERCP were examined in 27 patients: 23with pancreatic cancers, 4 with chronic pancreatitis. K-fas point mutation was detected with the polymerase chain reaction and restriction fragment-length polymorphism (PCR-RFLP). Telomerase activity was detected by PCR and telomeric repeat amplification protocol assay (PCR-TRAPELISA).RESULTS: The telomerase activities in 27 patients were measured in 21 exfoliated cell samples obtained from pancreatic duct brushings. D450 value of telomerase activities in pancreatic cancer and chronic pancreatitis were 0.446±0.27and 0.041±0.0111, respectively. Seventy-seven point eight percent (14/18) of patients with pancreatic cancer and none of the patients with chronic pancreatitis showed telomerase activity in cells collected from pancreatic duct brushings when cutoff value of telomerase activity was set at 2.0. The K-ras gene mutation rate (72.2%) in pancreatic cancer was higher than that in chronic pancreatitis (33.3%)(P<0.05). In considering of both telomerase activities and K-ras point mutation, the total positive rate was 83.3%(15/18), and the specificity was 100%.CONCLUSION: Changes of telomerase activities and K-ras point mutation at codon 12 may be an early event of malignant progression in pancreatic cancer. Detection of telomerase activity and K-ras point mutation at codon 12may be complementary to each other, and is useful in diagnosis of pancreatic cancer.

  13. DNA-directed Polymerase Subunits Play a Vital Role in Human Telomeric Overhang Processing

    OpenAIRE

    Diotti, Raffaella; Kalan, Sampada; Matveyenko, Anastasiya; Loayza, Diego

    2014-01-01

    Telomeres consist of TTAGGG repeats bound by the shelterin complex and end with a 3' overhang. In humans, telomeres shorten at each cell division, unless telomerase (TERT) is expressed and able to add telomeric repeats. For effective telomere maintenance, the DNA strand complementary to that made by telomerase must be synthesized. Recent studies have discovered a link between different activities necessary to process telomeres in the S-phase of the cell cycle in order to ref...

  14. The antiretroviral nucleoside analogue Abacavir reduces cell growth and promotes differentiation of human medulloblastoma cells

    OpenAIRE

    De Rossi, Alessandra; Russo, Giuseppe; Puca, Andrew; La Montagna, Raffaele; Caputo, Mariella; Mattioli, Eliseo; Lopez, Massimo; Giordano, Antonio; Pentimalli, Francesca

    2009-01-01

    Abacavir is one of the most efficacious nucleoside analogues, with a well-characterized inhibitory activity on reverse transcriptase enzymes of retroviral origin, and has been clinically approved for the treatment of AIDS. Recently, Abacavir has been shown to inhibit also the human telomerase activity. Telomerase activity seems to be required in essentially all tumours for the immortalization of a subset of cells, including cancer stem cells. In fact, many cancer cells are dependent on telome...

  15. Telomerase activity is increased and telomere length shortened in T cells from blood of patients with atopic dermatitis and psoriasis

    DEFF Research Database (Denmark)

    Wu, Kehuai; Higashi, N; Hansen, E R;

    2000-01-01

    We studied telomerase activity and telomere length in PBMC and purified CD4(+) and CD8(+) T cells from blood obtained from a total of 32 patients with atopic dermatitis, 16 patients with psoriasis, and 30 normal controls. The telomerase activity was significantly increased in PBMC from the patients......(+) T cell subsets from normal donors. In conclusion, the increased telomerase activity and shortened telomere length indicates that T lymphocytes in atopic dermatitis and psoriasis are chronically stimulated and have an increased cellular turnover in vivo....

  16. Telomerase gene therapy rescues telomere length, bone marrow aplasia, and survival in mice with aplastic anemia.

    Science.gov (United States)

    Bär, Christian; Povedano, Juan Manuel; Serrano, Rosa; Benitez-Buelga, Carlos; Popkes, Miriam; Formentini, Ivan; Bobadilla, Maria; Bosch, Fatima; Blasco, Maria A

    2016-04-01

    Aplastic anemia is a fatal bone marrow disorder characterized by peripheral pancytopenia and marrow hypoplasia. The disease can be hereditary or acquired and develops at any stage of life. A subgroup of the inherited form is caused by replicative impairment of hematopoietic stem and progenitor cells due to very short telomeres as a result of mutations in telomerase and other telomere components. Abnormal telomere shortening is also described in cases of acquired aplastic anemia, most likely secondary to increased turnover of bone marrow stem and progenitor cells. Here, we test the therapeutic efficacy of telomerase activation by using adeno-associated virus (AAV)9 gene therapy vectors carrying the telomeraseTertgene in 2 independent mouse models of aplastic anemia due to short telomeres (Trf1- andTert-deficient mice). We find that a high dose of AAV9-Terttargets the bone marrow compartment, including hematopoietic stem cells. AAV9-Terttreatment after telomere attrition in bone marrow cells rescues aplastic anemia and mouse survival compared with mice treated with the empty vector. Improved survival is associated with a significant increase in telomere length in peripheral blood and bone marrow cells, as well as improved blood counts. These findings indicate that telomerase gene therapy represents a novel therapeutic strategy to treat aplastic anemia provoked or associated with short telomeres. PMID:26903545

  17. Biosensor Techniques Used for Determination of Telomerase Activity in Cancer Cells

    Directory of Open Access Journals (Sweden)

    Evgeny Katz

    2008-01-01

    Full Text Available Measuring telomerase activity has proven successful for the determination of cancer in malignant somatic cells. Early conventional methods for the detection of telomerase activity include in vitro analysis via a primer extension assay, and the telomeric repeat amplification protocol (TRAP assay. TRAP incorporates the polymerase chain reaction (PCR step to increase the sensitivity of a given sample. However, research suggests that the TRAP technique suffers from false negative results, caused by failure of its PCR step. Other limitations of TRAP include the post-PCR steps involving polyacrylamide gel electrophoresis which are time inefficient. Thus, various efforts have been made to eliminate the PCR step of TRAP by using a variety of biosensor detection devices. This review mainly focuses on these alternatives including: optical, electrochemical, magnetic, and nanowire conductive signaling techniques to measure the telomerase activity produced via label free biosensor assay—via biocatalytic labels involving beacons, DNAzyme, ferrocenyl-naphthalene diimides, avidin-alkaline phosphatase and semiconductor quantum dots (QDs. These biosensor techniques are sensitive and provide precise and rapid results in the detection of telomerase activity.

  18. Biosensor Techniques Used for Determination of Telomerase Activity in Cancer Cells

    Science.gov (United States)

    Kulla, Eliona; Katz, Evgeny

    2008-01-01

    Measuring telomerase activity has proven successful for the determination of cancer in malignant somatic cells. Early conventional methods for the detection of telomerase activity include in vitro analysis via a primer extension assay, and the telomeric repeat amplification protocol (TRAP) assay. TRAP incorporates the polymerase chain reaction (PCR) step to increase the sensitivity of a given sample. However, research suggests that the TRAP technique suffers from false negative results, caused by failure of its PCR step. Other limitations of TRAP include the post-PCR steps involving polyacrylamide gel electrophoresis which are time inefficient. Thus, various efforts have been made to eliminate the PCR step of TRAP by using a variety of biosensor detection devices. This review mainly focuses on these alternatives including: optical, electrochemical, magnetic, and nanowire conductive signaling techniques to measure the telomerase activity produced via label free biosensor assay—via biocatalytic labels involving beacons, DNAzyme, ferrocenyl-naphthalene diimides, avidin-alkaline phosphatase and semiconductor quantum dots (QDs). These biosensor techniques are sensitive and provide precise and rapid results in the detection of telomerase activity.

  19. Telomerase Recruitment in Saccharomyces cerevisiae Is Not Dependent on Tel1-Mediated Phosphorylation of Cdc13

    Science.gov (United States)

    Gao, Hua; Toro, Tasha B.; Paschini, Margherita; Braunstein-Ballew, Bari; Cervantes, Rachel B.; Lundblad, Victoria

    2010-01-01

    In Saccharomyces cerevisiae, association between the Est1 telomerase subunit and the telomere-binding protein Cdc13 is essential for telomerase to be recruited to its site of action. A current model proposes that Tel1 binding to telomeres marks them for elongation, as the result of phosphorylation of a proposed S/TQ cluster in the telomerase recruitment domain of Cdc13. However, three observations presented here argue against one key aspect of this model. First, the pattern of Cdc13 phosphatase-sensitive isoforms is not altered by loss of Tel1 function or by mutations introduced into two conserved serines (S249 and S255) in the Cdc13 recruitment domain. Second, an interaction between Cdc13 and Est1, as monitored by a two-hybrid assay, is dependent on S255 but Tel1-independent. Finally, a derivative of Cdc13, cdc13–(S/TQ)11→(S/TA)11, in which every potential consensus phosphorylation site for Tel1 has been eliminated, confers nearly wild-type telomere length. These results are inconsistent with a model in which the Cdc13–Est1 interaction is regulated by Tel1-mediated phosphorylation of the Cdc13 telomerase recruitment domain. We propose an alternative model for the role of Tel1 in telomere homeostasis, which is based on the assumption that Tel1 performs the same molecular task at double-strand breaks (DSBs) and chromosome termini. PMID:20837994

  20. HOT1 is a mammalian direct telomere repeat-binding protein contributing to telomerase recruitment

    NARCIS (Netherlands)

    Kappei, D.; Butter, F.; Benda, C.; Scheibe, M.; Draskovic, Irena; Stevense, M.; Novo, C.L.; Basquin, C.; Araki, M.; Araki, K.; Krastev, D.B.; Kittler, R.; Jessberger, R.; Londono-Vallejo, J.A.; Mann, M.; Buchholz, F.

    2013-01-01

    Telomeres are repetitive DNA structures that, together with the shelterin and the CST complex, protect the ends of chromosomes. Telomere shortening is mitigated in stem and cancer cells through the de novo addition of telomeric repeats by telomerase. Telomere elongation requires the delivery of the

  1. Telomerase activity in needle biopsies from prostate cancer and benign prostates

    NARCIS (Netherlands)

    Wymenga, LFA; Wisman, GBA; Ruiters, MHJ; Mensink, HJA; Veenstra, R.

    2000-01-01

    Background Telomerase activation is thought to be essential for the immortality of cancer cells. It may be a prognostic factor in small volume well differentiated prostate cancers and hence a guide for the aggressiveness of the approach. The length of the chromosome tips (telomeres) are maintained b

  2. Regulative Function of Telomerase and Extracelluar Regulated Protein Kinases to Leukemic Cell Apoptosis

    Institute of Scientific and Technical Information of China (English)

    李登举; 张瑶珍; 曹文静; 孙岚; 徐慧珍; 路武

    2002-01-01

    Summary: In order to investigate the regulative function of telomerase and phosphorylated (acti-vated) extracelluar regulated protein kinase (ERK) i and 2 in the leukemic cell lines HL-60 andK562 proliferation inhibition and apoptosis, three chemotherapeutic drugs Harringtonine (HRT),Vincristine(VCR)and Etoposide(Vp16)were selected as inducers. The proliferation inhibition ratewas detected by MTT method, the cell cycle and cell apoptosis was analyzed by flow cytometryand the telomerase activity was detected by the telomeric repeat amplification protocol (TRAP)assay and bioluminescence analysis method. The phosphorylated ERK1/2 protein expression wasdetected by western blot method. The results showed that HRT, VCR and Vp16 could inhibit cellproliferation, induce apoptosis, inhibit telomerase activity and down-regulate the protein expres-sion of phosphorylated ERK. It was suggested that ERK signal transduction pathway was involvedin the down-regulation of telomerase activity and the onset of apoptosis in the leukemic cells treat-ed by HRT, VCR and Vp16.

  3. Allium telomeres unmasked: the unusual telomeric sequence (CTCGGTTATGGG)(n) is synthesized by telomerase

    Czech Academy of Sciences Publication Activity Database

    Fajkus, Petr; Peška, Vratislav; Sitová, Z.; Fulnečková, Jana; Dvořáčková, Martina; Gogola, M.; Sýkorová, Eva; Hapala, J.; Fajkus, J.

    2016-01-01

    Roč. 85, č. 3 (2016), s. 337-347. ISSN 0960-7412 R&D Projects: GA ČR(CZ) GP13-10948P Institutional support: RVO:68081707 Keywords : Allium * unusual telomere * telomerase Subject RIV: BO - Biophysics Impact factor: 5.972, year: 2014

  4. RPA regulates telomerase action by providing Est1p access to chromosome ends.

    Science.gov (United States)

    Schramke, Vera; Luciano, Pierre; Brevet, Vanessa; Guillot, Sylvine; Corda, Yves; Longhese, Maria Pia; Gilson, Eric; Géli, Vincent

    2004-01-01

    Replication protein A (RPA) is a highly conserved single-stranded DNA-binding protein involved in DNA replication, recombination and repair. We show here that RPA is present at the telomeres of the budding yeast Saccharomyces cerevisiae, with a maximal association in S phase. A truncation of the N-terminal region of Rfa2p (associated with the rfa2Delta40 mutated allele) results in severe telomere shortening caused by a defect in the in vivo regulation of telomerase activity. Cells carrying rfa2Delta40 show impaired binding of the protein Est1p, which is required for telomerase action. In addition, normal telomere length can be restored by expressing a Cdc13-Est1p hybrid protein. These findings indicate that RPA activates telomerase by loading Est1p onto telomeres during S phase. We propose a model of in vivo telomerase action that involves synergistic action of RPA and Cdc13p at the G-rich 3' overhang of telomeric DNA. PMID:14702040

  5. Risk of multiple myeloma is associated with polymorphisms within telomerase genes and telomere length

    DEFF Research Database (Denmark)

    Campa, Daniele; Martino, Alessandro; Varkonyi, Judit;

    2015-01-01

    had longer telomeres compared to controls (OR = 1.19; 95% CI: 0.63-2.24; p(trend)  = 0.01 comparing the quartile with the longest LTL versus the shortest LTL). Our data suggest the hypothesis of decreased disease risk by genetic variants that reduce the efficiency of the telomerase complex. This...

  6. Telomerase is essential to alleviate pif1-induced replication stress at telomeres

    NARCIS (Netherlands)

    Chang, Michael; Luke, Brian; Kraft, Claudine; Li, Zhijian; Peter, Matthias; Lingner, Joachim; Rothstein, Rodney

    2009-01-01

    Pif1, an evolutionarily conserved helicase, negatively regulates telomere length by removing telomerase from chromosome ends. Pif1 has also been implicated in DNA replication processes such as Okazaki fragment maturation and replication fork pausing. We find that overexpression of Saccharomyces cerv

  7. Telomerase recruitment in Saccharomyces cerevisiae is not dependent on Tel1-mediated phosphorylation of Cdc13.

    Science.gov (United States)

    Gao, Hua; Toro, Tasha B; Paschini, Margherita; Braunstein-Ballew, Bari; Cervantes, Rachel B; Lundblad, Victoria

    2010-12-01

    In Saccharomyces cerevisiae, association between the Est1 telomerase subunit and the telomere-binding protein Cdc13 is essential for telomerase to be recruited to its site of action. A current model proposes that Tel1 binding to telomeres marks them for elongation, as the result of phosphorylation of a proposed S/TQ cluster in the telomerase recruitment domain of Cdc13. However, three observations presented here argue against one key aspect of this model. First, the pattern of Cdc13 phosphatase-sensitive isoforms is not altered by loss of Tel1 function or by mutations introduced into two conserved serines (S249 and S255) in the Cdc13 recruitment domain. Second, an interaction between Cdc13 and Est1, as monitored by a two-hybrid assay, is dependent on S255 but Tel1-independent. Finally, a derivative of Cdc13, cdc13-(S/TQ)11→(S/TA)11, in which every potential consensus phosphorylation site for Tel1 has been eliminated, confers nearly wild-type telomere length. These results are inconsistent with a model in which the Cdc13-Est1 interaction is regulated by Tel1-mediated phosphorylation of the Cdc13 telomerase recruitment domain. We propose an alternative model for the role of Tel1 in telomere homeostasis, which is based on the assumption that Tel1 performs the same molecular task at double-strand breaks (DSBs) and chromosome termini. PMID:20837994

  8. Formation and stabilization of the telomeric antiparallel G-quadruplex and inhibition of telomerase by novel benzothioxanthene derivatives with anti-tumor activity

    Science.gov (United States)

    Zhang, Wen; Chen, Min; Ling Wu, Yan; Tanaka, Yoshimasa; Juan Ji, Yan; Lin Zhang, Su; He Wei, Chuan; Xu, Yan

    2015-09-01

    G-quadruplexes formed in telomeric DNA sequences at human chromosome ends can be a novel target for the development of therapeutics for the treatment of cancer patients. Herein, we examined the ability of six novel benzothioxanthene derivatives S1-S6 to induce the formation of and stabilize an antiparallel G-quadruplex by EMSA, UV-melting and CD techniques and the influence of S1-S6 on A549 and SGC7901 cells through real-time cell analysis, wound healing, trap assay methods. Results show that six compounds could differentially induce 26 nt G-rich oligonucleotides to form the G-quadruplex with high selectivity vs C-rich DNA, mutated DNA and double-stranded DNA, stabilize it with high affinity, promote apoptosis and inhibit mobility and telomerase activity of A549 cells and SGC7901 cells. Especially, S1, S3, S4 displayed stronger abilities, of which S3 was the most optimal with the maximum ΔTm value being up to 29.8 °C for G-quadruplex, the minimum IC50 value being 0.53 μM and the maximum cell inhibitory rate being up to 97.2%. This study suggests that this type of compounds that induce the formation of and stabilize the telomeric antiparallel G-quadruplex, and consequently inhibit telomerase activity, leading to cell apoptosis, can be screened for the discovery of novel antitumor therapeutics.

  9. Risk of progression of early cervical lesions is associated with integration and persistence of HPV-16 and expression of E6, Ki-67, and telomerase

    Directory of Open Access Journals (Sweden)

    Arianna Vega-Peña

    2013-01-01

    Full Text Available Background: Low-grade squamous intraepithelial lesions (LSIL are the earliest lesions of the uterine cervix, the persistence and integration of high-risk human papillomavirus (HR-HPV as type 16, which promotes the development of more aggressive lesions. Aim: To select more aggressive lesions with tendency to progress to invasive cervical cancer. Materials and Methods: A total of 75 cytological specimens in liquid base (Liqui-PREP were analyzed: 25 specimens were with no signs of SIL (NSIL and without HPV; 25 NSIL with HPV-16, and 25 with both LSIL and HPV-16. The expression of Ki-67, telomerase, and viral E6 was evaluated by immunocytochemistry; and the detection of viral DNA was done by polymerase chain reaction (PCR and restriction fragment length polymorphism (RFLPs for genotyping or sequencing of HPV-16. The physical state of HPV-16 was evaluated by in situ hybridization with amplification with tyramide. Results: Of the total group, 58.6% had LSIL associated with persistence and of these 59.3% was associated with integrated state of HPV as intense expression of E6, Ki-67 (P = 0.013, P = 0.055 has except for the expression of telomerase present a non-significant association (P<0.341. Conclusions: Overexpression of E6 and Ki-67 is associated with the integration of HPV-16, favoring viral persistence, and increasing the risk of progression in women with NSIL and LSIL.

  10. Dynamic telomerase gene suppression via network effects of GSK3 inhibition.

    Directory of Open Access Journals (Sweden)

    Alan E Bilsland

    Full Text Available BACKGROUND: Telomerase controls telomere homeostasis and cell immortality and is a promising anti-cancer target, but few small molecule telomerase inhibitors have been developed. Reactivated transcription of the catalytic subunit hTERT in cancer cells controls telomerase expression. Better understanding of upstream pathways is critical for effective anti-telomerase therapeutics and may reveal new targets to inhibit hTERT expression. METHODOLOGY/PRINCIPAL FINDINGS: In a focused promoter screen, several GSK3 inhibitors suppressed hTERT reporter activity. GSK3 inhibition using 6-bromoindirubin-3'-oxime suppressed hTERT expression, telomerase activity and telomere length in several cancer cell lines and growth and hTERT expression in ovarian cancer xenografts. Microarray analysis, network modelling and oligonucleotide binding assays suggested that multiple transcription factors were affected. Extensive remodelling involving Sp1, STAT3, c-Myc, NFkappaB, and p53 occurred at the endogenous hTERT promoter. RNAi screening of the hTERT promoter revealed multiple kinase genes which affect the hTERT promoter, potentially acting through these factors. Prolonged inhibitor treatments caused dynamic expression both of hTERT and of c-Jun, p53, STAT3, AR and c-Myc. CONCLUSIONS/SIGNIFICANCE: Our results indicate that GSK3 activates hTERT expression in cancer cells and contributes to telomere length homeostasis. GSK3 inhibition is a clinical strategy for several chronic diseases. These results imply that it may also be useful in cancer therapy. However, the complex network effects we show here have implications for either setting.

  11. The pif1 helicase, a negative regulator of telomerase, acts preferentially at long telomeres.

    Directory of Open Access Journals (Sweden)

    Jane A Phillips

    2015-04-01

    Full Text Available Telomerase, the enzyme that maintains telomeres, preferentially lengthens short telomeres. The S. cerevisiae Pif1 DNA helicase inhibits both telomerase-mediated telomere lengthening and de novo telomere addition at double strand breaks (DSB. Here, we report that the association of the telomerase subunits Est2 and Est1 at a DSB was increased in the absence of Pif1, as it is at telomeres, suggesting that Pif1 suppresses de novo telomere addition by removing telomerase from the break. To determine how the absence of Pif1 results in telomere lengthening, we used the single telomere extension assay (STEX, which monitors lengthening of individual telomeres in a single cell cycle. In the absence of Pif1, telomerase added significantly more telomeric DNA, an average of 72 nucleotides per telomere compared to the 45 nucleotides in wild type cells, and the fraction of telomeres lengthened increased almost four-fold. Using an inducible short telomere assay, Est2 and Est1 no longer bound preferentially to a short telomere in pif1 mutant cells while binding of Yku80, a telomere structural protein, was unaffected by the status of the PIF1 locus. Two experiments demonstrate that Pif1 binding is affected by telomere length: Pif1 (but not Yku80 -associated telomeres were 70 bps longer than bulk telomeres, and in the inducible short telomere assay, Pif1 bound better to wild type length telomeres than to short telomeres. Thus, preferential lengthening of short yeast telomeres is achieved in part by targeting the negative regulator Pif1 to long telomeres.

  12. The pif1 helicase, a negative regulator of telomerase, acts preferentially at long telomeres.

    Science.gov (United States)

    Phillips, Jane A; Chan, Angela; Paeschke, Katrin; Zakian, Virginia A

    2015-04-01

    Telomerase, the enzyme that maintains telomeres, preferentially lengthens short telomeres. The S. cerevisiae Pif1 DNA helicase inhibits both telomerase-mediated telomere lengthening and de novo telomere addition at double strand breaks (DSB). Here, we report that the association of the telomerase subunits Est2 and Est1 at a DSB was increased in the absence of Pif1, as it is at telomeres, suggesting that Pif1 suppresses de novo telomere addition by removing telomerase from the break. To determine how the absence of Pif1 results in telomere lengthening, we used the single telomere extension assay (STEX), which monitors lengthening of individual telomeres in a single cell cycle. In the absence of Pif1, telomerase added significantly more telomeric DNA, an average of 72 nucleotides per telomere compared to the 45 nucleotides in wild type cells, and the fraction of telomeres lengthened increased almost four-fold. Using an inducible short telomere assay, Est2 and Est1 no longer bound preferentially to a short telomere in pif1 mutant cells while binding of Yku80, a telomere structural protein, was unaffected by the status of the PIF1 locus. Two experiments demonstrate that Pif1 binding is affected by telomere length: Pif1 (but not Yku80) -associated telomeres were 70 bps longer than bulk telomeres, and in the inducible short telomere assay, Pif1 bound better to wild type length telomeres than to short telomeres. Thus, preferential lengthening of short yeast telomeres is achieved in part by targeting the negative regulator Pif1 to long telomeres. PMID:25906395

  13. Determination of telomerase activity in stem cells and non-stem cells of breast cancer

    Institute of Scientific and Technical Information of China (English)

    LI Zhi; HE Yanli; ZHANG Jiahua; ZHANG Jinghui; HUANG Tao

    2007-01-01

    Although all normal tissue cells,including stem cells,are genetically homologous,variation in gene expression patterns has already determined the distinct roles for individual cells in the physiological process due to the occurrence of epigenetic modification.This is of special importance for the existenee of tissue stem cells because they are exclusively immortal within the body,capable of selfreplicating and differentiating by which tissues renew and repair itself and the total tissue cell population maintains a steady-state.Impairment of tissue stem cells is usually accompanied by a reduction in cell number,slows down the repair process and causes hypofunction.For instance,chemotherapy usually leads to depression of bone marrow and hair loss.Cellular aging is closely associated with the continuous erosion of the telomere while activation of telomerase repairs and maintains telomeres,thus slowing the aging process and prolonging cell life.In normal adults,telomerase activation mainly presents in tissue stem cells and progenitor cells giving them unlimited growth potential.Despite the extensive demonstration of telomerase activation in malignancy(>80%),scientists found that heterogeneity also exists among the tumor cells and only minorities of cells,designated as cancer stem cells,andergo processes analogous to the self-renewal and differentiation of normal stem ceils while the rest have limited lifespans.In this study,telomerase activity was measured and compared in breast cancer stem cells and non-stem cells that were phenotypically sorted by examining surface marker expression.The results indicated that cancer stem cells show a higher level of enzyme activity than non-stem cells.In addition,associated with the repair of cancer tissue(or relapse)after chemotherapy,telomerase activity in stem cells was markedly increased.

  14. Expression of Mouse Telomerase Catalytic Subunit mTERT Gene in Testis of SD Rats and Its Significance

    Institute of Scientific and Technical Information of China (English)

    叶哲伟; 陈晓春; 杨述华; 陈江; 熊雅丽; 鲁功成

    2003-01-01

    To study the expression of mTERT gene in the testis of SD rats and its significance, insitu hybridization (ISH) techniques were used to detect the expression of telomerase gene mTERTmRNA in the testis of SD rats. The expression of mTERT was detectable in different-age male SDrats' testis. There was a positive correlation between the expression of mTERT and the location ofgerm cells (spermatogonia, spermatocyte, spermatid). In Sertoli cells, leydig cell and spermato-zoa, telomerase mTERT was not detected. Type A spermatogonia expressed the highest level of te-lomerase mTERT mRNA. Our results suggest that the expression of mTERT gene in the testis ofSD rats is of lifetime and coincide with the telomerase activity.

  15. The changes in telomerase activity and telomere length in HeLa cells undergoing apop- tosis induced by sodium butyrate

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The changes in telomerase activity and telomere length during apoptosis in HeLa cells as induced by sodium butyrate (SB) have been studied. After a 48 h SB treatment, HeLa cells demonstrated characteristic apoptotic hallmarks including chromatin condensation, formation of apoptotic bodies and DNA Laddering which were caused by the cleavage and degradation of DNA between nucleosomes. There were no significant changes in telomerase activity of apoptotic cells, while the telomere length shortened markedly. In the meanwhile, cells became more susceptible to apoptotic stimuli and telomere became more vulnerable to degradation after telomerase activity was inhibited. All the results suggest that the apoptosis induced by SB is closely related to telomere shortening, while telomerase enhances resistance of HeLa cells to apoptotic stimuli by protecting telomere.

  16. DNA-fueled molecular machine for label-free and non-enzymatic ultrasensitive detection of telomerase activity.

    Science.gov (United States)

    Sun, Panpan; Ran, Xiang; Liu, Chaoqun; Liu, Chaoying; Pu, Fang; Ren, Jinsong; Qu, Xiaogang

    2016-08-01

    Herein, a non-enzymatic and label-free strategy based on DNA-fueled molecular machine was developed for ultrasensitive detection of telomerase activity in cancer cell extracts even at the single-cell level. PMID:27405851

  17. In situ detection of TGF betas, TGF beta receptor II mRNA and telomerase activity in rat cholangiocarcinogenesis

    OpenAIRE

    Lu, Jian-ping; Mao, Jian-Qun; Li, Ming-Sheng; Lu, Shi-Lun; Hu, Xi-Qi; Zhu, Shi-Neng; Nomura, Shintaro

    2003-01-01

    AIM: Initial report on the in situ examination of the mRNA expression of transforming growth factor betas (TGFβs), TGFβ type II receptor (TβRII) and telomerase activity in the experimental rat liver tissue during cholangiocarcinogenesis.

  18. Telomerase inhibition by siRNA causes senescence and apoptosis in Barrett's adenocarcinoma cells: mechanism and therapeutic potential

    Directory of Open Access Journals (Sweden)

    Batchu Ramesh B

    2005-07-01

    Full Text Available Abstract Background In cancer cells, telomerase induction helps maintain telomere length and thereby bypasses senescence and provides enhanced replicative potential. Chemical inhibitors of telomerase have been shown to reactivate telomere shortening and cause replicative senescence and apoptotic cell death of tumor cells while having little or no effect on normal diploid cells. Results We designed siRNAs against two different regions of telomerase gene and evaluated their effect on telomere length, proliferative potential, and gene expression in Barrett's adenocarcinoma SEG-1 cells. The mixture of siRNAs in nanomolar concentrations caused a loss of telomerase activity that appeared as early as day 1 and was essentially complete at day 3. Inhibition of telomerase activity was associated with marked reduction in median telomere length and complete loss of detectable telomeres in more than 50% of the treated cells. Telomere loss caused senescence in 40% and apoptosis in 86% of the treated cells. These responses appeared to be associated with activation of DNA sensor HR23B and subsequent activation of p53 homolog p73 and p63 and E2F1. Changes in these gene regulators were probably the source of observed up-regulation of cell cycle inhibitors, p16 and GADD45. Elevated transcript levels of FasL, Fas and caspase 8 that activate death receptors and CARD 9 that interacts with Bcl10 and NFKB to enhance mitochondrial translocation and activation of caspase 9 were also observed. Conclusion These studies show that telomerase siRNAs can cause effective suppression of telomerase and telomere shortening leading to both cell cycle arrest and apoptosis via mechanisms that include up-regulation of several genes involved in cell cycle arrest and apoptosis. Telomerase siRNAs may therefore be strong candidates for highly selective therapy for chemoprevention and treatment of Barrett's adenocarcinoma.

  19. Effects of Treatment with Platinum Azidothymidine and Azidothymidine on Telomerase Activity and Bcl-2 Concentration in Hepatocellular Carcinoma- Induced Rats

    OpenAIRE

    Sabokrouh, Abdolreza; Goodarzi, Mohammad Taghi; Vaisi-raygani, Asad; Shohreh KHATAMI*; TAGHIZADEH-JAHED, MASOUD

    2014-01-01

    Background Telomerase activity increases in cancer cells. Bcl-2 is an antiapoptotic factor that its concentration grows in many cancer cells including hepato-cellular carcinoma cells. In this study, an attempt was made to investigate the effects of a new synthetic compound, platinum azidothymidine (Pt-AZT) on treatment of rats with Hepatocellular Carcinoma (HCC) and to compare its effects with azidothymidine (AZT) in alteration of telomerase activity and Bcl-2 concentration in HCC. Methods He...

  20. Comparison between Platinum-Azidothymidine and Azidothymidine Effects on Bcl-2 and Telomerase Gene Expression in Rats with Hepatocellular Carcinoma

    OpenAIRE

    Sabokrouh, Abdolreza; Vaisi-raygani, Asad; Goodarzi, Mohammad Taghi; Shohreh KHATAMI*; Taghizadeh-jahed, Massoud; Shahabadi, Nahid; Lakpour, Niknam; Shakiba, Yadollah

    2015-01-01

    Background: High expression of telomerase and Bcl-2 are reported in hepatocellular carcinoma. Some anticancer drugs show their effects through reduction of these factors. In this study, it was aimed to investigate the effects of a new synthetic compound, platinum azidothymidine, on inhibition of telomerase and Bcl-2 expression in hepatocellular carcinoma compared to azidothymidine. Methods: To study the effects of Pt-AZT on hepatocellular carcinoma and compare its effects with AZT in inhibiti...