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  1. 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.

  2. Apigenin decreases cell viability and telomerase activity in human leukemia cell lines.

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    Jayasooriya, R G P T; Kang, Sang-Hyuck; Kang, Chang-Hee; Choi, Yung Hyun; Moon, Dong-Oh; Hyun, Jin-Won; Chang, Weon-Young; Kim, Gi-Young

    2012-08-01

    Recent studies have shown that apigenin (4',5,7-trihydroxyflavone inhibits human malignant cancer cell growth through cell cycle arrest and apoptosis. However, the underlying relationship between apoptosis and telomerase activity in response to apigenin exposure is not well understood. In this study, we found that apigenin significantly induces direct cytotoxicity in human leukemia cells (U937, THP-1 and HL60) through activation of the caspase pathway. As we presumed, treatment with apigenin was found to increase the level of intracellular reactive oxygen species (ROS), whereas pretreatment with antioxidants, N-acetyl-cysteine (NAC) or glutathione (GSH), completely attenuated ROS generation. Surprisingly, these antioxidants did not promote recuperation from apigenin-induced cell death. We further showed that apigenin downregulates telomerase activity in caspase-dependent apoptosis and observed that apigenin dosing results in downregulation of telomerase activity by suppression of c-Myc-mediated telomerase reverse transcriptase (hTERT) expression. In addition, treatment of apigenin-dosed cells with the two antioxidants did not restore telomerase activity. Taken together, this data suggests that ROS is not essential for suppression of apigenin-mediated apoptosis associated with the activation of caspases and regulation of telomerase activity via suppression of hTERT. We conclude that apigenin has a direct cytotoxic effect and the loss of telomerase activity in leukemia cells. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Telomerase Activation in Hematological Malignancies

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    Joana Ropio

    2016-09-01

    Full Text Available Telomerase expression and telomere maintenance are critical for cell proliferation and survival, and they play important roles in development and cancer, including hematological malignancies. Transcriptional regulation of the rate-limiting subunit of human telomerase reverse transcriptase gen (hTERT is a complex process, and unveiling the mechanisms behind its reactivation is an important step for the development of diagnostic and therapeutic applications. Here, we review the main mechanisms of telomerase activation and the associated hematologic malignancies.

  4. Decreasing Pin1 suppresses telomerase activity by NF-κB in HCT116 cells colorectal carcinoma

    Institute of Scientific and Technical Information of China (English)

    Jianwen Sun; Lijun Fan; Meining Li; Yuehong Zhang; Niuliang Cheng

    2013-01-01

    Objective: The aim of our study was to investigate the effect of Pin1 on the telomerase activity in human colorectal carcinoma HCT116 cells. Methods: Firstly, we transfected plasmid pGenesil-1-Pin1 (p-shRNA) using liposome (Lipofectamine 2000) into colorectal cancer HCT-116 cells to down-regulate the expression of Pin1. To detect the apoptotic rate of HCT116 cells was by cytometry (FCM). The expression of Pin1 and hTERT at RNA levels in human colorectal cancer HCT116 cells were determined by RT-PCR. To evaluate the activity of telomerase was by TRAP-silver staining. The subcellular localization and accumulative level of p-NF-κB/p65 protein at the nuclear was detected by Immunofluorescence and Western blotting. The DNA-binding activity of NF-κB/p65 was detected by electrophoretic mobility shift assay (EMSA). Results: Using liposome into colorectal cancer HCT-116 cells, and down-regulate the expression of Pin1 (0.392 ± 0.072-fold; P = 0.001), and the apoptotic rate was increased (11.40% ± 1.54%; P < 0.05). Compared with transfected p-CON cell group, in transfected p-shRNA cell group, the transcription of hTERT was lower (0.171 ± 0.060-fold; P = 0.001) by quantitative real-time RT-PCR, and the results of TRAP-silver staining analysis suggested that the telomerase activity was significantly declined (0.384 ± 0.015-fold; P < 0.05). Furthermore, it was demonstrated by Immunofluorescence that p-NF-κB/p65 had a nuclear localization, and the level of p-NF-κB/p65 protein at the nuclear was reduced with silencing the expression of Pin1 by Western blotting. Using EMSA, it was suggested that NF-κB/p65 was able to bind to hTERT promoter, and the direct interaction was declined with silencing the expression of Pin1. Conclusion: Taken together, silencing Pin1 may suppress activity of telomerase and the expression of hTERT by inhibiting NF-κB/p65 activity and reducing the combination of NF-κB/p65 and hTERT gene promoter.

  5. [Telomere length, telomerase activity, stress and aging].

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    Spivak, I M; Mikhelson, V M; Spivak, D L

    2015-01-01

    The review is dedicated to analysis of data available at present time concerning possible influence of stress upon telomere lengths and telomerase activity, as well as various ways of counteracting it. Present-day telomerase theory of aging gains a new impetus, shedding light upon the influence of psychological state of humans and their ability to counteract stress, upon the process of aging. It also tends to regard telomere shortening and the decrease in the activity of telomerase as a marker of level of the ability to adapt to both inner and outer influences. Both aging and age-dependent diseases are proved to be substantially retarded not only by the administration of drugs, but also by psychological means, which forms a good way towards healthy longevity. With complete understanding of the impossibility to prevent or even to slow down natural senescence itself, these methods allow to remove causes, which accelerate senescence, and to increase the average human longevity.

  6. DETECTION OF TELOMERASE ACTIVITY IN BREAST CARCINOMA

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    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. Human telomerase: biogenesis, trafficking, recruitment, and activation.

    Science.gov (United States)

    Schmidt, Jens C; Cech, Thomas R

    2015-06-01

    Telomerase is the ribonucleoprotein enzyme that catalyzes the extension of telomeric DNA in eukaryotes. Recent work has begun to reveal key aspects of the assembly of the human telomerase complex, its intracellular trafficking involving Cajal bodies, and its recruitment to telomeres. Once telomerase has been recruited to the telomere, it appears to undergo a separate activation step, which may include an increase in its repeat addition processivity. This review covers human telomerase biogenesis, trafficking, and activation, comparing key aspects with the analogous events in other species.

  8. CHIP promotes human telomerase reverse transcriptase degradation and negatively regulates telomerase activity.

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    Lee, Ji Hoon; Khadka, Prabhat; Baek, Seung Han; Chung, In Kwon

    2010-12-31

    The maintenance of eukaryotic telomeres requires telomerase, which is minimally composed of a telomerase reverse transcriptase (TERT) and an associated RNA component. Telomerase activity is tightly regulated by expression of human (h) TERT at both the transcriptional and post-translational levels. The Hsp90 and p23 molecular chaperones have been shown to associate with hTERT for the assembly of active telomerase. Here, we show that CHIP (C terminus of Hsc70-interacting protein) physically associates with hTERT in the cytoplasm and regulates the cellular abundance of hTERT through a ubiquitin-mediated degradation. Overexpression of CHIP prevents nuclear translocation of hTERT and promotes hTERT degradation in the cytoplasm, thereby inhibiting telomerase activity. In contrast, knockdown of endogenous CHIP results in the stabilization of cytoplasmic hTERT. However, it does not affect the level of nuclear hTERT and has no effect on telomerase activity and telomere length. We further show that the binding of CHIP and Hsp70 to hTERT inhibits nuclear translocation of hTERT by dissociating p23. However, Hsp90 binding to hTERT was not affected by CHIP overexpression. These results suggest that CHIP can remodel the hTERT-chaperone complexes. Finally, the amount of hTERT associated with CHIP peaks in G(2)/M phases but decreases during S phase, suggesting a cell cycle-dependent regulation of hTERT. Our data suggest that CHIP represents a new pathway for modulating telomerase activity in cancer.

  9. Telomerase activity in human cancer

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    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.

  10. 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.

  11. Prevalence of Telomerase Activity in Human Cancer

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    Chi-Hau Chen

    2011-05-01

    Full Text Available Telomerase activity has been measured in a wide variety of cancerous and non-cancerous tissue types, and the vast majority of clinical studies have shown a direct correlation between it and the presence of cancerous cells. Telomerase plays a key role in cellular immortality and tumorigenesis. Telomerase is activated in 80–90% of human carcinomas, but not in normal somatic cells, therefore, its detection holds promise as a diagnostic marker for cancer. Measurable levels of telomerase have been detected in malignant cells from various samples: tissue from gestational trophoblastic neoplasms; squamous carcinoma cells from oral rinses; lung carcinoma cells from bronchial washings; colorectal carcinoma cells from colonic luminal washings; bladder carcinoma cells from urine or bladder washings; and breast carcinoma or thyroid cancer cells from fine needle aspirations. Such clinical tests for telomerase can be useful as non-invasive and cost-effective methods for early detection and monitoring of cancer. In addition, telomerase activity has been shown to correlate with poor clinical outcome in late-stage diseases such as non-small cell lung cancer, colorectal cancer, and soft tissue sarcomas. In such cases, testing for telomerase activity can be used to identify patients with a poor prognosis and to select those who might benefit from adjuvant treatment. Our review of the latest medical advances in this field reveals that telomerase holds great promise as a biomarker for early cancer detection and monitoring, and has considerable potential as the basis for developing new anticancer therapies.

  12. 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.

  13. Telomerase activity and telomere length in Daphnia.

    Science.gov (United States)

    Schumpert, Charles; Nelson, Jacob; Kim, Eunsuk; Dudycha, Jeffry L; Patel, Rekha C

    2015-01-01

    Telomeres, comprised of short repetitive sequences, are essential for genome stability and have been studied in relation to cellular senescence and aging. Telomerase, the enzyme that adds telomeric repeats to chromosome ends, is essential for maintaining the overall telomere length. A lack of telomerase activity in mammalian somatic cells results in progressive shortening of telomeres with each cellular replication event. Mammals exhibit high rates of cell proliferation during embryonic and juvenile stages but very little somatic cell proliferation occurs during adult and senescent stages. The telomere hypothesis of cellular aging states that telomeres serve as an internal mitotic clock and telomere length erosion leads to cellular senescence and eventual cell death. In this report, we have examined telomerase activity, processivity, and telomere length in Daphnia, an organism that grows continuously throughout its life. Similar to insects, Daphnia telomeric repeat sequence was determined to be TTAGG and telomerase products with five-nucleotide periodicity were generated in the telomerase activity assay. We investigated telomerase function and telomere lengths in two closely related ecotypes of Daphnia with divergent lifespans, short-lived D. pulex and long-lived D. pulicaria. Our results indicate that there is no age-dependent decline in telomere length, telomerase activity, or processivity in short-lived D. pulex. On the contrary, a significant age dependent decline in telomere length, telomerase activity and processivity is observed during life span in long-lived D. pulicaria. While providing the first report on characterization of Daphnia telomeres and telomerase activity, our results also indicate that mechanisms other than telomere shortening may be responsible for the strikingly short life span of D. pulex.

  14. Telomerase Activity and Telomere Length in Daphnia

    Science.gov (United States)

    Schumpert, Charles; Nelson, Jacob; Kim, Eunsuk; Dudycha, Jeffry L.; Patel, Rekha C.

    2015-01-01

    Telomeres, comprised of short repetitive sequences, are essential for genome stability and have been studied in relation to cellular senescence and aging. Telomerase, the enzyme that adds telomeric repeats to chromosome ends, is essential for maintaining the overall telomere length. A lack of telomerase activity in mammalian somatic cells results in progressive shortening of telomeres with each cellular replication event. Mammals exhibit high rates of cell proliferation during embryonic and juvenile stages but very little somatic cell proliferation occurs during adult and senescent stages. The telomere hypothesis of cellular aging states that telomeres serve as an internal mitotic clock and telomere length erosion leads to cellular senescence and eventual cell death. In this report, we have examined telomerase activity, processivity, and telomere length in Daphnia, an organism that grows continuously throughout its life. Similar to insects, Daphnia telomeric repeat sequence was determined to be TTAGG and telomerase products with five-nucleotide periodicity were generated in the telomerase activity assay. We investigated telomerase function and telomere lengths in two closely related ecotypes of Daphnia with divergent lifespans, short-lived D. pulex and long-lived D. pulicaria. Our results indicate that there is no age-dependent decline in telomere length, telomerase activity, or processivity in short-lived D. pulex. On the contrary, a significant age dependent decline in telomere length, telomerase activity and processivity is observed during life span in long-lived D. pulicaria. While providing the first report on characterization of Daphnia telomeres and telomerase activity, our results also indicate that mechanisms other than telomere shortening may be responsible for the strikingly short life span of D. pulex. PMID:25962144

  15. 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.

  16. DETECTION OF TELOMERASE ACTIVITY IN PATIENTS WITH MYCOSIS FUNGOIDES

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    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.

  17. Typhonium flagelliforme decreases telomerase expression in HeLa cervical cancer cells

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    Endang Purwaningsih

    2016-05-01

    Conclusion Typhonium flagelliforme extract at different doses is capable of decreasing telomerase expression more effectively in cervical cancer cells than in breast cancer cells. This study shows that Typhonium flagelliforme may have anti-cancer activity, necessitating further investigations.

  18. Dynamics of telomerase activity in response to acute psychological stress

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    Epel, Elissa S.; Lin, Jue; Dhabhar, Firdaus S.; Wolkowitz, Owen M.; Puterman, E; Karan, Lori; Blackburn, Elizabeth H.

    2010-01-01

    Telomerase activity plays an essential role in cel0l survival, by lengthening telomeres and promoting cell growth and longevity. It is now possible to quantify the low levels of telomerase activity in human leukocytes. Low basal telomerase activity has been related to chronic stress in people and to chronic glucocorticoid exposure in vitro. Here we test whether leukocyte telomerase activity changes under acute psychological stress. We exposed 44 elderly women, including 22 high stress dementia caregivers and 22 matched low stress controls, to a brief laboratory psychological stressor, while examining changes in telomerase activity of peripheral blood mononuclear cells (PBMC). At baseline, caregivers had lower telomerase activity levels than controls, but during stress telomerase activity increased similarly in both groups. Across the entire sample, subsequent telomerase activity increased by 18% one hour after the end of the stressor (p<0.01). The increase in telomerase activity was independent of changes in numbers or percentages of monocytes, lymphocytes, and specific T cell types, although we cannot fully rule out some potential contribution from immune cell redistribution in the change in telomerase activity. Telomerase activity increases were associated with greater cortisol increases in response to the stressor. Lastly, psychological response to the tasks (greater threat perception) was also related to greater telomerase activity increases in controls. These findings uncover novel relationships of dynamic telomerase activity with exposure to an acute stressor, and with two classic aspects of the stress response -- perceived psychological stress and neuroendocrine (cortisol) responses to the stressor. PMID:20018236

  19. 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.

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

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    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.

  1. ARSENIC EFFECTS ON TELOMERE AND TELOMERASE ACTIVITY

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    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. 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.

  3. The conserved Est1 protein stimulates telomerase DNA extension activity

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    DeZwaan, Diane C.; Freeman, Brian C.

    2009-01-01

    The first telomerase cofactor identified was the budding yeast protein Est1, which is conserved through humans. While it is evident that Est1 is required for telomere DNA maintenance, understanding its mechanistic contributions to telomerase regulation has been limited. In vitro, the primary effect of Est1 is to activate telomerase-mediated DNA extension. Although Est1 displayed specific DNA and RNA binding, neither activity contributed significantly to telomerase stimulation. Rather Est1 mediated telomerase upregulation through direct contacts with the reverse transcriptase subunit. In addition to intrinsic Est1 functions, we found that Est1 cooperatively activated telomerase in conjunction with Cdc13 and that the combinatorial effect was dependent upon a known salt-bridge interaction between Est1 (K444) and Cdc13 (E252). Our studies provide insights into the molecular events used to control the enzymatic activity of the telomerase holoenzyme. PMID:19805136

  4. 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.

  5. Dysfunctional telomeres promote genomic instability and metastasis in the absence of telomerase activity in oncogene induced mammary cancer.

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    Bojovic, Bojana; Crowe, David L

    2013-02-01

    Telomerase is a ribonucleoprotein that maintains the ends of chromosomes (telomeres). In normal cells lacking telomerase activity, telomeres shorten with each cell division because of the inability to completely synthesize the lagging strand. Critically shortened telomeres elicit DNA damage responses and limit cellular division and lifespan, providing an important tumor suppressor function. Most human cancer cells express telomerase which contributes significantly to the tumor phenotype. In human breast cancer, telomerase expression is predictive of clinical outcomes such as lymph node metastasis and survival. In mouse models of mammary cancer, telomerase expression is also upregulated. Telomerase overexpression resulted in spontaneous mammary tumor development in aged female mice. Increased mammary cancer also was observed when telomerase deficient mice were crossed with p53 null mutant animals. However, the effects of telomerase and telomere length on oncogene driven mammary cancer have not been completely characterized. To address these issues we characterized neu proto-oncogene driven mammary tumor formation in G1 Terc-/- (telomerase deficient with long telomeres), G3 Terc-/- (telomerase deficient with short telomeres), and Terc+/+ mice. Telomerase deficiency reduced the number of mammary tumors and increased tumor latency regardless of telomere length. Decreased tumor formation correlated with increased apoptosis in Terc deficient tumors. Short telomeres dramatically increased lung metastasis which correlated with increased genomic instability, and specific alterations in DNA copy number and gene expression. We concluded that short telomeres promote metastasis in the absence of telomerase activity in neu oncogene driven mammary tumors.

  6. The Clinical Study of Telomerase Activity in Gastric Tumor

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    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.

  7. Critical telomerase activity for uncontrolled cell growth

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    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.

  8. Telomerase activity and the risk of lung cancer.

    Science.gov (United States)

    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

    2012-02-01

    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 cancer patients than in controls (mean ± standard deviation; 1.32 ± 1.65 vs 2.60 ± 3.09, P lung cancer increased as telomerase activity reduced (P(trend) = 1 × 10(-4)). Moreover, when the subjects were categorized based on the median value of telomerase activity, subjects with low telomerase activity were at a significantly increased risk of lung cancer compared to subjects with high telomerase activity (adjusted odds ratio = 3.05, 95% confidence interval = 1.60-5.82, P = 7 × 10(-4)). These findings suggest that telomerase activity may affect telomere maintenance, thereby contributing to susceptibility to lung cancer.

  9. 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

  10. Functional Assessment of Pharmacological Telomerase Activators in Human T Cells

    Directory of Open Access Journals (Sweden)

    Rita B. Effros

    2013-01-01

    Full Text Available Telomeres are structures at the ends of chromosomes that shorten during cell division and eventually signal an irreversible state of growth arrest known as cellular senescence. To delay this cellular aging, human T cells, which are critical in the immune control over infections and cancer, activate the enzyme telomerase, which binds and extends the telomeres. Several different extracts from the Astragalus membranaceus root have been documented to activate telomerase activity in human T cells. The objective of this research was to compare two extracts from Astragalus membranaceus, TA-65 and HTA, for their effects on both telomerase and proliferative activity of human CD4 and CD8 T cells. Our results demonstrate that, TA-65 increased telomerase activity significantly (1.3 to 3.3-fold relative to controls in T cell cultures from six donors tested, whereas HTA only increased telomerase levels in two out of six donors. We also demonstrate that TA-65 activates telomerase by a MAPK- specific pathway. Finally, we determine that during a three-day culture period, only the T cells treated with the TA-65 extract showed a statistically significant increase in proliferative activity. Our results underscore the importance of comparing multiple telomerase activators within the same experiment, and of including functional assays in addition to measuring telomerase activity.

  11. 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.

  12. The inhibitory effect of Curcuma longa extract on telomerase activity ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-02-08

    Feb 8, 2010 ... telomerase activity in A549 lung cancer cell line. Pourhassan ..... in human leukemia cell HL-60 is associated with inhibition of telomerase activity. Mol. ... metastatic non-small-cell lung cancer: a global view. BMC Proc. 2(2): p.

  13. 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.

  14. Rhodacyanine dye MKT-077 inhibits in vitro telomerase assay but has no detectable effects on telomerase activity in vivo.

    Science.gov (United States)

    Wadhwa, Renu; Colgin, Lorel; Yaguchi, Tomoko; Taira, Kazunari; Reddel, Roger R; Kaul, Sunil C

    2002-08-01

    MKT-077, a cationic rhodacyanine dye analogue, causes selective toxicity to cancer cells. Its cellular targets elucidated thus far include oncogenic Ras, F-actin, mortalin (hmot-2)/mthsp70, and telomerase. Here we report that MKT-077 causes growth arrest of cancer cells in culture independent of their Ras, p53, or telomerase status. Telomerase activity is inhibited in vitro by MKT-077 in the telomerase assay used. However, the in vivo toxicity seen in telomerase-positive cancer cells was not accompanied by inhibition of telomerase activity or telomere shortening. Furthermore, cells with an alternative mechanism for lengthening of telomeres were also sensitive to MKT-077 and showed enhanced formation of alternative mechanism for lengthening of telomeres-associated PML bodies in their nuclei. The data suggested that inhibition of telomerase activity is unlikely to be a prime cause of MKT-077-induced toxicity in cancer cells.

  15. Telomerase Activity and Genetic Alterations in Primary Breast Carcinomas

    Directory of Open Access Journals (Sweden)

    Anna Papadopoulou

    2003-03-01

    Full Text Available It has been proposed that the structural and numerical chromosome abnormalities recorded in breast cancer could be the result of telomere dysfunction and that telomerase is activated de novo to provide a survival mechanism curtailing further chromosomal aberrations. However, recent in vivo and in vitro data show that the ectopic expression of telomerase promotes tumorigenesis via a telomere length-independent mechanism. In this study, the relation between telomerase expression and the extent of chromosomal aberrations was investigated in 62 primary breast carcinomas. Telomerase activity was measured using a polymerase chain reaction-based telomeric repeat amplification protocol assay and 92% of the tumors were found to express telomerase with a relative activity ranging from 0 to 3839.6. Genetic alterations were determined by G-banding and comparative genomic hybridization analysis and 97% of the tumors exhibited chromosomal aberrations ranging from 0 to 44 (average: 10.98. In the overall series, the relationship between telomerase activity levels and genetic changes could be best described by a quadratic model, whereas in tumors with below-average genetic alteration numbers, a significant positive association was recorded between the two variables (coefficient=0.374, P= .017. The relationship between telomerase activity levels and the extent of genetic alteration may reflect the complex effect of telomerase activation upon tumor progression in breast carcinomas.

  16. Telomerase activity coevolves with body mass, not lifespan

    Science.gov (United States)

    Seluanov, Andrei; Chen, Zhuoxun; Hine, Christopher; Sasahara, Tais H. C.; Ribeiro, Antonio A. C. M.; Catania, Kenneth C.; Presgraves, Daven C.; Gorbunova, Vera

    2009-01-01

    Summary In multicellular organisms, telomerase is required to maintain telomere length in the germline but is dispensable in the soma. Mice, for example, express telomerase in somatic and germline tissues, while humans express telomerase almost exclusively in the germline. As a result, when telomeres of human somatic cells reach a critical length the cells enter irreversible growth arrest called replicative senescence. Replicative senescence is believed to be an anticancer mechanism that limits cell proliferation. The difference between mice and humans led to the hypothesis that repression of telomerase in somatic cells has evolved as a tumor-suppressor adaptation in large, long-lived organisms. We tested whether regulation of telomerase activity coevolves with lifespan and body mass using comparative analysis of 15 rodent species with highly diverse lifespans and body masses. Here we show that telomerase activity does not coevolve with lifespan but instead coevolves with body mass: larger rodents repress telomerase activity in somatic cells. These results suggest that large body mass presents a greater risk of cancer than long lifespan, and large animals evolve repression of telomerase activity to mitigate that risk. PMID:17173545

  17. Telomere attrition and restoration in the normal teleost Oryzias latipes are linked to growth rate and telomerase activity at each life stage.

    Science.gov (United States)

    Hatakeyama, Hitoshi; Yamazaki, Hiromi; Nakamura, Ken-Ichi; Izumiyama-Shimomura, Naotaka; Aida, Junko; Suzuki, Hiroetsu; Tsuchida, Shuichi; Matsuura, Masaaki; Takubo, Kaiyo; Ishikawa, Naoshi

    2016-01-01

    Telomere shortening occurs when cells divide, both in vitro and in vivo. On the other hand, telomerase is able to maintain telomere length in cells by adding TTAGGG repeats to the ends of telomeres. However, the interrelationships existing among telomere length, telomerase activity and growth in vertebrates remain to be clarified. In the present study we measured telomere length (terminal restriction fragment length), telomerase activity and body growth of Oryzias latipes from the embryo stage until senescence. During the rapid growth stage (age 0-7 months), telomeres shortened in parallel with decreasing telomerase activity. Then, during adolescence (age 7 months - 1 year), telomeres lengthened quickly as growth slowed and telomerase activity increased. In the adult stage (age 1-4 years) characterized by little growth, telomerase activity decreased gradually and telomeres shortened. Our data indicate that telomere attrition and restoration are linked to growth and telomerase activity, and suggest that critical loss of telomere homeostasis is associated with mortality in this animal.

  18. 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.

  19. 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.

  20. Human telomerase activity, telomerase and telomeric template expression in hepatic stem cells and in livers from fetal and postnatal donors.

    Science.gov (United States)

    Schmelzer, Eva; Reid, Lola M

    2009-10-01

    Although telomerase activity has been analyzed in various normal and malignant tissues, including liver, it is still unknown to what extent telomerase can be associated with specific maturational lineage stages. We assessed human telomerase activity, protein and gene expression for the telomerase reverse transcriptase, as well as expression of the telomeric template RNA hTER in hepatic stem cells and in various developmental stages of the liver from fetal to adult. In addition, the effect of growth factors on telomerase activity was analyzed in hepatic stem cells in vitro. Telomerase was found to be highly active in fetal liver cells and was significantly higher than in hepatic stem cells, correlating with gene and protein expression levels. Activity in postnatal livers from all donor ages varied considerably and did not correlate with age or gene expression levels. The hter expression could be detected throughout the development. A short stimulation by growth factors of cultured hepatic stem cells did not increase telomerase activity. Telomerase is considerably active in fetal liver and variably in postnatal livers. Although telomerase protein is present at varying levels in liver cells of all donor ages, gene expression is solely associated with fetal liver cells.

  1. 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.

  2. A sensitive, label-free electrochemical detection of telomerase activity without modification or immobilization.

    Science.gov (United States)

    Liu, Xu; Wei, Min; Xu, Ensheng; Yang, Haitang; Wei, Wei; Zhang, Yuanjian; Liu, Songqin

    2017-05-15

    Telomerase has become one of the most typical tumor marker because it is closely related to cancers. In this paper, a simple label-free electrochemical detection of telomerase activity by using methylene blue (MB) as a G-quadruplex binding probe was proposed, avoiding commonly used complex label procedures, nano-probe synthesis, complicated electrode modification, probe immobilization or signal amplification. In the presence of telomerase substrate (TS) primer, the binding of MB on primer was weak. When repeats of (TTAGGG) were extended on the TS primer under the action of telomerase, they formed multiple G-quadruplexes with the help of K(+). As a result, a large amount of MB bounded to multiple G-quadruplexes because they have more strong interaction with G-quadruplexes than TS primer. As a result, the diffusion current of MB decreased sharply, which was strongly dependent on the telomerase activity. The DPV current change has a linear correlation with the logarithm of HeLa cell number in the range of 10-10,000 cells, with the detection limit of 3 cells. The high sensitivity was due to the formed multiple G-quadruplexes. Using indium tin oxide (ITO) as working electrode without modification ensured the good reproducibility of the method. The method was also simple, rapid, and has been successfully applied in the telomerase activity detection in urine with good selectivity and reproducibility, which is significant for cancer diagnosis, anticancer drugs screening, and cancer therapy evaluation.

  3. Effect of Lidamycin on Telomerase Activity in Human Hepatoma BEL-7402 Cells

    Institute of Scientific and Technical Information of China (English)

    RUI-JUAN GAO; YUE-XIN LIANG; DIAN-DONG LI; HONG-YIN ZHANG; YONG-SU ZHEN

    2007-01-01

    Objective To investigate the effect of lidamycin(LDM)on telomerase activity in human hepatoma BEL-7402 cells under the condition of LDM inducing mitotic cell death and senescence.Methods Chromatin condensation was detected by co-staining with Hoechst 33342 and PI.Cell multinucleation was observed by Giemsa staining and genomic DNA was separated by agarose gel electrophoresis.Fluorescent intensity of Rho123 Was determined for mitochondrial membrane potential.MTT assay and SA-β-gal staining were employed to analyze the senescence-like phenotype.The expression of proteins was analyzed by Western blot.Telomerase activity was assayed by telomerase PCR-ELISA.Results Mitotic cell death occurred in LDM-treated cells characterized by unique and atypical chromatin condensation,multinucleation and increased mitochondrial membrane potential.However,no apoptotic bodies or DNA ladders were found.In addition,apoptosis-related proteins remained nearly unaltered.Senescence-like phenotype was identified by increased and elongated size of cells,growth retardation,enhanced SA-β-gal activity and the changes of senescence-related protein expression.Telomerase activity markedly decreased (P<0.01)in LDM-treated hepatoma BEL-7402 cells. Conelusion Mitotic cell death and senescence could be triggered simultaneously or sequentially after exposure of hepatoma BEL-7402 cells to LDM.The decrease in telomerase activity may play a key role in the defective mitosis and aging morphology.Further investigation of detailed mechanism is needed.

  4. 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.

  5. High Telomerase Activity Correlates with the Stabilities of Genome and DNA Ploidy in Renal Cell Carcinoma

    Directory of Open Access Journals (Sweden)

    Hideki Izumi

    2002-01-01

    Full Text Available Malignant tumors have telomerase activity, which is thought to play a critical role in tumor growth. However, the relation between telomerase activity and genomic DNA status in tumor cells is poorly understood. In the present study, we examined telomerase activity in 13 clear cell type renal cell carcinomas (CRCCs with similar clinicopathologic features by telomeric repeat amplification protocol assay (TRAP. Based on TRAP assay results, we divided the CRCCs into two groups: a high telomerase activity group and a low/no telomerase activity group. We then analyzed genomic aberration, DNA ploidy, and telomere status in these two groups by comparative genomic hybridization (CGH, laser scanning cytometry (LSC, and telomere-specific fluorescence in situ hybridization (T-FISH, respectively. CGH showed the high telomerase activity group to have fewer genomic changes than the low/no telomerase activity group, which had many genomic aberrations. Moreover, with LSC, DNA diploid cells were found more frequently in the high telomerase activity group than in the low/no telomerase activity group. In addition, T-FISH revealed strong telomere signal intensity in the high telomerase activity group compared with that of the low/no telomerase activity group. These results suggest that telomerase activity is linked to genomic DNA status and that high telomerase activity is associated with genomic stability, DNA ploidy, and telomere length in CRCC.

  6. 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.

  7. 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.

  8. 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.

  9. Metastases suppressor NME2 associates with telomere ends and telomerase and reduces telomerase activity within cells.

    Science.gov (United States)

    Kar, Anirban; Saha, Dhurjhoti; Purohit, Gunjan; Singh, Ankita; Kumar, Parveen; Yadav, Vinod Kumar; Kumar, Pankaj; Thakur, Ram Krishna; Chowdhury, Shantanu

    2012-03-01

    Analysis of chromatin-immunoprecipitation followed by sequencing (ChIP-seq) usually disregards sequence reads that do not map within binding positions (peaks). Using an unbiased approach, we analysed all reads, both that mapped and ones that were not included as part of peaks. ChIP-seq experiments were performed in human lung adenocarcinoma and fibrosarcoma cells for the metastasis suppressor non-metastatic 2 (NME2). Surprisingly, we identified sequence reads that uniquely represented human telomere ends in both cases. In vivo presence of NME2 at telomere ends was validated using independent methods and as further evidence we found intranuclear association of NME2 and the telomere repeat binding factor 2. Most remarkably, results demonstrate that NME2 associates with telomerase and reduces telomerase activity in vitro and in vivo, and sustained NME2 expression resulted in reduced telomere length in aggressive human cancer cells. Anti-metastatic function of NME2 has been demonstrated in human cancers, however, mechanisms are poorly understood. Together, findings reported here suggest a novel role for NME2 as a telomere binding protein that can alter telomerase function and telomere length. This presents an opportunity to investigate telomere-related interactions in metastasis suppression.

  10. Telomere length and telomerase activity in the context of menopause.

    Science.gov (United States)

    Pines, A

    2013-12-01

    Telomere length is a marker of cell aging, since shorter telomeres and a higher rate of telomere shortening with time are associated with poorer health status and survival. Various factors may determine telomere length and the function of the telomere maintenance system, including the hereditary load and several modifiable variables such as diet and lifestyle. Telomere length and telomerase activity were investigated extensively in a variety of diseases, such as malignancies (i.e. breast and colon cancer), cardiovascular disease and its related metabolic risk factors, cognitive, mental and psychiatric conditions, and many others. Some evidence points at an association between longer endogenous estrogen exposure (length of reproductive years of life) and greater telomere length and lower telomerase activity. However, there is probably no correlation in regard to menopause per se or the use of hormone therapy. Changing the nutrition and implementing healthy lifestyles may improve the telomere/telomerase parameters in postmenopausal women, but better understanding of this system is still needed.

  11. Telomerase inhibition decreases alpha-fetoprotein expression and secretion by hepatocellular carcinoma cell lines: in vitro and in vivo study.

    Directory of Open Access Journals (Sweden)

    Roula Tahtouh

    Full Text Available Alpha-fetoprotein (AFP is a diagnostic marker for hepatocellular carcinoma (HCC. A direct relationship between poor prognosis and the concentration of serum AFP has been observed. Telomerase, an enzyme that stabilizes the telomere length, is expressed by 90% of HCC. The aim of this study was to investigate the effect of telomerase inhibition on AFP secretion and the involvement of the PI3K/Akt/mTOR signaling pathway. Proliferation and viability tests were performed using tetrazolium salt. Apoptosis was determined through the Annexin V assay using flow cytometry. The concentrations of AFP were measured using ELISA kits. The AFP mRNA expression was evaluated using RT-PCR, and cell migration was evaluated using a Boyden chamber assay. The in vivo effect of costunolide on AFP production was tested in NSG mice. Telomerase inhibition by costunolide and BIBR 1532 at 5 and 10 μM decreased AFP mRNA expression and protein secretion by HepG2/C3A cells. The same pattern was obtained with cells treated with hTERT siRNA. This treatment exhibited no apoptotic effect. The AFP mRNA expression and protein secretion by PLC/PRF/5 was decreased after treatment with BIBR1532 at 10 μM. In contrast, no effect was obtained for PLC/PRF/5 cells treated with costunolide at 5 or 10 μM. Inhibition of the PI3K/Akt/mTOR signaling pathway decreased the AFP concentration. In contrast, the MAPK/ERK pathway appeared to not be involved in HepG2/C3A cells, whereas ERK inhibition decreased the AFP concentration in PLC/PRF/5 cells. Modulation of the AFP concentration was also obtained after the inhibition or activation of PKC. Costunolide (30 mg/kg significantly decreased the AFP serum concentration of NSG mice bearing HepG2/C3A cells. Both the inhibition of telomerase and the inhibition of the PI3K/Akt/mTOR signaling pathway decreased the AFP production of HepG2/C3A and PLC/PRF/5 cells, suggesting a relationship between telomerase and AFP expression through the PI3K

  12. 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.

  13. Effects of cisplatin on telomerase activity and telomere length in BEL-7404 human hepatoma cells

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Telomerase activity was inhibited in a dose and time-dependent manner with the treatment of cisplatin for 24, 48, or 72 h in a concentration ranged from 0.8 to 50 μM in BEL-7404 human hepatoma cells. There were no changes in expression pattern of three telomerase subunits, its catalytic reverse transcriptase subunit (hTERT), its RNA component (hTR) or the associated protein subunit (TP1), after cisplatin treated for 72 h with indicated concentrations. Mean telomere lengths were decreased by the cisplatin treatment. Cell growth inhibition and cell cycle accumulation in G2/M phase were found to be correlated with telomerase inhibition in the present study, but percentages of cell apoptosis did not change markedly during the process.

  14. The correlation between telomerase activity and Bax/Bcl-2 ratio in valproic acid-treated MCF-7 breast cancer cell line

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    Zahra Vafaiyan

    2015-07-01

    Conclusion: Our study demonstrated that cell viability of MCF-7 cells was decreased after treatment with VPA, probably through a reduction of telomerase activity and an increase in Bax/bcl-2 ratio. Therefore, it could be concluded that VPA is a potent anti-cancer agent for breast cancer cells through inhibition of telomerase activity and induction of apoptosis.

  15. Inhibitory effects of antisense phosphorothioate oligodeoxynucleotides on pancreatic cancer cell Bxpc-3 telomerase activity and cell growth in vitro

    Institute of Scientific and Technical Information of China (English)

    Yun-Feng Wang; Ke-Jian Guo; Bei-Ting Huang; Yong Liu; Xiao-Yun Tang; Jian-Jun Zhang; Qiang Xia

    2006-01-01

    AIM: To investigate the effect of telomerase hTERT gene antisense oligonucleotide (hTERT-ASO) on proliferation and telomerase activity of pancreatic cancer cell line Bxpc-3.METHODS: MTT assay was used to detect the effect of different doses of hTERT-ASO on proliferation of Bxpc-3 cell for different times. To study the anti-tumor activity,the cells were divided into there groups: Control group (pancreatic cancer cell Bxpc-3); antisense oligonucleotide (hTERT-ASO) group; and nosense oligonucleotide group decorated with phosphorothioate. Telomerase activity was detected using TRAP-PCR-ELISA. Cell DNA distribution was examined using flow cytometry assay.Cell apoptosis was observed by transmission electron microscope in each group.RESULTS: After treatment with 6 mmol/L hTERTASO, cell proliferation was inhibited in dose- and timedependent manner. The telomerase activity decreased after treatment with hTERT-ASO for 72 h. Flow cytometry showed the cell number of G0/G1 phase increased from 2.7% to 14.7%, the cell number of S phase decreased from 72.7% to 51.0%, and a sub-G1 stage cell apoptosis peak appeared in front of G1 stage.CONCLUSION: Telomerase antisense oligodeoxynucleotide can inhibit the proliferation of pancreatic cancer cell line Bxpc-3 and decrease the telomerase activity and increase cell apoptosis rate in vitro.

  16. 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.

  17. Telomere shortening and telomerase activity in ischaemic cardiomyopathy patients

    DEFF Research Database (Denmark)

    Sawhney, V; Campbell, N G; Brouilette, S W

    2016-01-01

    difference in the age and sex adjusted mean telomere length analysed by qPCR between the groups (p=0.88). In contrast, the load-of-short telomeres assessed by Universal-STELA method and telomerase activity by TRAP assay were both higher in patients who had appropriate ICD therapy and were significantly...

  18. 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.

  19. Native gel electrophoresis of human telomerase distinguishes active complexes with or without dyskerin

    Science.gov (United States)

    Gardano, Laura; Holland, Linda; Oulton, Rena; Le Bihan, Thierry; Harrington, Lea

    2012-01-01

    Telomeres, the ends of linear chromosomes, safeguard against genome instability. The enzyme responsible for extension of the telomere 3′ terminus is the ribonucleoprotein telomerase. Whereas telomerase activity can be reconstituted in vitro with only the telomerase RNA (hTR) and telomerase reverse transcriptase (TERT), additional components are required in vivo for enzyme assembly, stability and telomere extension activity. One such associated protein, dyskerin, promotes hTR stability in vivo and is the only component to co-purify with active, endogenous human telomerase. We used oligonucleotide-based affinity purification of hTR followed by native gel electrophoresis and in-gel telomerase activity detection to query the composition of telomerase at different purification stringencies. At low salt concentrations (0.1 M NaCl), affinity-purified telomerase was ‘supershifted’ with an anti-dyskerin antibody, however the association with dyskerin was lost after purification at 0.6 M NaCl, despite the retention of telomerase activity and a comparable yield of hTR. The interaction of purified hTR and dyskerin in vitro displayed a similar salt-sensitive interaction. These results demonstrate that endogenous human telomerase, once assembled and active, does not require dyskerin for catalytic activity. Native gel electrophoresis may prove useful in the characterization of telomerase complexes under various physiological conditions. PMID:22187156

  20. Effects of PCB126 and PCB153 on telomerase activity and telomere length in undifferentiated and differentiated HL-60 cells.

    Science.gov (United States)

    Xin, Xing; Senthilkumar, P K; Schnoor, Jerald L; Ludewig, Gabriele

    2016-02-01

    PCBs are persistent organic pollutants that are carcinogenic and immunotoxic and have developmental toxicity. This suggests that they may interfere with normal cell maturation. Cancer and stem/progenitor cells have telomerase activity to maintain and protect the chromosome ends, but lose this activity during differentiation. We hypothesized that PCBs interfere with telomerase activity and the telomere complex, thereby disturbing cell differentiation and stem/progenitor cell function. HL-60 cells are cancer cells that can differentiated into granulocytes and monocytes. We exposed HL-60 cells to PCB126 (dioxin-like) and PCB153 (nondioxin-like) 6 days before and during 3 days of differentiation. The differentiated cells showed G0/G1 phase arrest and very low telomerase activity. hTERT and hTR, two telomerase-related genes, were downregulated. The telomere shelterins TRF1, TRF2, and POT1 were upregulated in granulocytes, and TRF2 was upregulated and POT1 downregulated in monocytes. Both PCBs further reduced telomerase activity in differentiated cells, but had only small effects on the differentiation and telomere-related genes. Treatment of undifferentiated HL-60 cells for 30 days with PCB126 produced a downregulation of telomerase activity and a decrease of hTERT, hTR, TRF1, and POT1 gene expression. With PCB153, the effects were less pronounced and some shelterin genes were increased after 30 days of exposure. With each PCB, no differentiation of cells was observed and cells continued to proliferate despite reduced telomerase activity, resulting in shortened telomeres after 30 days of exposure. These results indicate cell-type and PCB congener-specific effects on telomere/telomerase-related genes. Although PCBs do not seem to strongly affect differentiation, they may influence stem or progenitor cells through telomere attrition with potential long-term consequences for health.

  1. 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.

  2. 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.

  3. 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.

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

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    Lorenzo Montanaro

    2008-01-01

    Full Text Available 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 expression of other important components of the telomerase complex such as telomerase reverse transcriptase (TERT. In vitro experiments showed that reduction of dyskerin expression affect telomerase activity through the reduction of TERC. Only when TERC levels were strongly reduced telomerase activity was hindered. Retroviral mediated over-expression of TERC abolished the telomerase impairment due to dyskerin knock down. In conclusion, our results indicated that, beside its effect on ribosome biogenesis, the levels of dyskerin in cancer cells modulate telomerase activity through the regulation of TERC levels, independently of TERT expression. This should be taken into consideration when utilizing TERT expression as a surrogate indicator of telomerase activity in tumour pathology.

  5. Coevolution of telomerase activity and body mass in mammals: from mice to beavers.

    Science.gov (United States)

    Gorbunova, Vera; Seluanov, Andrei

    2009-01-01

    Telomerase is repressed in the majority of human somatic tissues. As a result human somatic cells undergo replicative senescence, which plays an important role in suppressing tumorigenesis, and at the same time contributes to the process of aging. Repression of somatic telomerase activity is not a universal phenomenon among mammals. Mice, for example, express telomerase in somatic tissues, and mouse cells are immortal when cultured at physiological oxygen concentration. What is the status of telomerase in other animals, beyond human and laboratory mouse, and why do some species evolve repression of telomerase activity while others do not? Here we discuss the data on telomere biology in various mammalian species, and a recent study of telomerase activity in a large collection of wild rodent species, which showed that telomerase activity coevolves with body mass, but not lifespan. Large rodents repress telomerase activity, while small rodents maintain high levels of telomerase activity in somatic cells. We discuss a model that large body mass presents an increased cancer risk, which drives the evolution of telomerase suppression and replicative senescence.

  6. 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.

  7. EFFECTS OF THE HYPERTHERMIA AND HARRINGTONINE ON TELOMERASE ACTIVITY OF HL-60 CELLS

    Institute of Scientific and Technical Information of China (English)

    王宝燕; 张海涛; 李静

    2002-01-01

    Objective To understand the mechanism of the hype rthermia and harringtonine in purging of leukemia cells In Vitro. telomerase activity of HL-60 cells treated by hyperthermia (42℃ for one hour) and di fferent concentrations of Harringtonine were investigated.Methods Using Telomeric Repeats Amplification Protocol (TRAP) a nd ELISA techniques to analyze the telomerase activity of HL-60 cells. Results Our results showed that harringtonine inhibited the tel omerase activity of HL-60 cells in a dosage related manner. Moreover, the telom erase activity of HL-60 cells was significantly decreased after the hyperthermi a treatment as compared with untreated cells.Conclusion The effect of the hyperthermia and Harringtonine on purging leukemia cells In Vitro may be mediated by down regulation of telome rase activity of tumor cells.

  8. [Telomerase activity in esophageal carcinoma and lesions unstained with Lugol's solution].

    Science.gov (United States)

    Yoneyama, K; Aoyama, N; Koizumi, H; Tamai, S

    1998-05-01

    Telomerase is a specific enzyme required for the replication of telomeres. Its activity is detected in almost human cancers. We examined in esophageal carcinoma and lesions unstained with Lugol's solution telomerase activity by using telomeric repeat amplification protocol (TRAP) assay. Telomerase activity was detected in all 22 esophageal carcinomas, regardless of histopathological findings. In unstained lesions, telomerase activity was detected in 15 of 22; 10 squamous cell carcinomas, four dysplasia, one regenerative epithelium, no telomerase activity was found in seven; four normal esophageal epithelia, two Barrett's esophagi, one regenerative epithelium. These results suggest that telomerase activity may be a useful molecular marker for the diagnosis of esophageal carcinoma and of the early esophageal carcinoma in area unstained with Lugol's solution.

  9. 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.

  10. 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.

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

    Science.gov (United States)

    Januszkiewicz, Danuta; Wysoki, Jacek; Lewandowski, Krzysztof; Pernak, Monika; Nowicka, Karina; Rembowska, Jolanta; Nowak, Jerzy

    2003-12-01

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

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

    Science.gov (United States)

    Murillo-Ortiz, Blanca; Astudillo-De la Vega, Horacio; Castillo-Medina, Sebastian; Malacara, JM; Benitez-Bribiesca, Luis

    2006-01-01

    Background 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. Methods 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. Results 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). Conclusion 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. PMID:16911782

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

    Directory of Open Access Journals (Sweden)

    Malacara JM

    2006-08-01

    Full Text Available Abstract Background 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. Methods 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. Results 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. Conclusion 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.

  14. Brief Report: Differential Effects of Tenofovir, Abacavir, Emtricitabine, and Darunavir on Telomerase Activity In Vitro.

    Science.gov (United States)

    Stella-Ascariz, Natalia; Montejano, Rocío; Pintado-Berninches, Laura; Monge, Susana; Bernardino, José I; Pérez-Valero, Ignacio; Montes, María L; Mingorance, Jesús; Perona, Rosario; Arribas, José R

    2017-01-01

    In vitro, tenofovir and abacavir induced a significant dose-dependent inhibition of telomerase activity at therapeutic concentrations in peripheral blood mononuclear cells of healthy subjects. Median inhibition of telomerase activity by tenofovir at 0.5 and 1 μM was 29% [Interquartile range (IQR) 29%-34%, P = 0.042] and 28% (IQR 28%-41%, P = 0.042), respectively. Abacavir inhibition was 12% (IQR 9%-13%, P = 0.043) at 3 μM and 14% (IQR 10%-29%, P = 0.043) at 10 μM. Tenofovir and abacavir did not change human telomerase reverse transcriptase (hTERT) levels or mRNA levels of other telomerase complex genes. Exposure to emtricitabine or darunavir did not affect telomerase activity, hTERT protein levels, or mRNA levels of telomerase/shelterin genes.

  15. 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.

  16. Effect of Estrogen on Telomerase Activity in Human Breast Cancer Cells

    Institute of Scientific and Technical Information of China (English)

    高金波; 陈道达; 田元; 张锦辉; 蔡开琳

    2003-01-01

    To investigate the effects of estrogen(E2 ) on telomerase activity and its mechanism inhuman breast cancer cells, estrogen receptor positive MCF-7 cells were treated with different con-centrations of E2. Telomerase activity was measured by using TRAP-ELISA method, the cell cyclephases analyzed by using flow cytometry, and the expression of Cyclin D1 detected by using immu-nohistochemistry method. The results showed that telomerase activity levels were increased inMCF-7 cells treated with 10-8 mol/L E2 during the observed period (P<0.05), and E2 increasedtelomerase activity levels in a dose-dependent manner(10-10- 10-8 mol/L); Simultaneously, thecell cycle phases of MCF-7 cells treated with 10-8 mol/L E2 were changed significantly: G0/G1phase decreased from 60.52% to 50. 93%, S phase increased from 29.03% to 30.83%; However,the expression of Cyclin D1 was decreased. It was concluded that estrogen can upregulate telomeraseactivity of MCF-7 cells, and the effect can be blocked by antiestrogen tamoxifen. Its mechanismmay be closely associated with modulation of cell cycle phases.

  17. MicroRNA-mediated NBS1 Gene Silence and Its Effects on Telomerase Activation in Hela Cells

    Institute of Scientific and Technical Information of China (English)

    CAO Sun-qiong; REN Chang-shan

    2008-01-01

    Objective:To research the silence of NBS1 after transfection microRNA expressing eukaryotic recombinants and the changes of telomerase activation in teiomerase-positive cell line Hela.Methods:According to the sequence of NBS1 mRNA,the NBS1 pre-microRNA was designed and synthesized,then cloned into the GFP reporter pcDNA6.2-GW/EmGFP-miR vector and transfected into Hela cells.The integrity of the insert fragment was verified through colony PCR and sequencing analysis.The NBS1 gene expression of NBS1 microRNA recombinants was detected by Real-Time PCR and western blot.Telomerase activity in Hela cells was assayed by TRAP-PCR-EB.Results:Sequences of insert fragment in microRNA expressing recombinants were correct.The NBS1 gene expression was decreased,and the telomerase activation of Hela cell reduced.Conclusion:NBS1 microRNA inhibits NBS1 gene expression,and depresses telomerase activation of Hela cells.This confirms that there is relevance between NBS1 gene and telomerase activity.

  18. Troglitazone suppresses telomerase activity independently of PPARγ in estrogen-receptor negative breast cancer cells

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    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.

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

    Science.gov (United States)

    Gazzaniga, Francesca S; Blackburn, Elizabeth H

    2014-12-11

    Telomerase is a ribonucleoprotein complex that adds telomeric DNA to the ends of linear chromosomes. It contains two core canonical components: the essential RNA component, hTR, which provides the template for DNA synthesis, and the reverse transcriptase protein component, hTERT. Low telomerase activity in circulating peripheral blood mononuclear cells has been associated with a variety of diseases. It is unknown, however, whether telomerase, in addition to its long-term requirement for telomere maintenance, is also necessary for short-term immune cell proliferation and survival. We report that overexpression of enzymatically inactive hTR mutants protected against dexamethasone-induced apoptosis in stimulated CD4 T cells. Furthermore, hTR knockdown reproducibly induced apoptosis in the absence of any detectable telomere shortening or DNA damage response. In contrast, hTERT knockdown did not induce apoptosis. Strikingly, overexpression of hTERT protein caused apoptosis that was rescued by overexpression of enzymatically inactive hTR mutants. Hence, we propose that hTR can function as a noncoding RNA that protects from apoptosis independent of its function in telomerase enzymatic activity and long-term telomere maintenance in normal human immune cells. These results imply that genetic or environmental factors that alter hTR levels can directly affect immune cell function to influence health and disease.

  20. Telomerase Activity in Peripheral Blood Mononuclear Cells from Senile Patients with Pneumonia

    Institute of Scientific and Technical Information of China (English)

    LIU Jian; ZHOU Zhen; LIU Xiaoqing

    2006-01-01

    To investigate the changes of the activity of telomerase in peripheral blood mononuclear cells (PBMCs) from senile patients with pneumonia, the telomerase activity was examined before and after the stimulation of phytohemagglutinin-M (PHA-M) in PBMCs from 10 control subjects (group A), 12 non-senile patients with pneumonia (group B) and 9 senile patients with pneumonia (group C). Also observed was the proliferative response of these PBMCs to PHA-M. The results showed that, both with or without the stimulation of PHA-M, the values of telomerase activity in PBMCs from group C patients (A values: pre-stimulation, 0.43±0.04; post-stimulation, 0.63±0.03) were significantly lower than those in PBMCs from both group A patients (A values: prestimulation, 0.65±0.05;post-stimulation, 1.26±0.13;P<0.001, respectively) and group B patients (A values: pre-stimulation, 0.63±0.03; post-stimulation, 0.93±0.03;P<0.05, respectively). The results of MTT test showed that the proliferative activity of PBMCs in group C patients (A value: 0.35±0.03) was also significantly lower than that in group A patients (A value:0. 55±0.04; P<0.05) and group B patients (A value: 0.46±0.03;P<0.05). These results indicate that the telomerase activity decreases in senile patients with pneumonia, which may be one of the mechanisms for the weakened immune function in those patients.

  1. Modulation of yeast telomerase activity by Cdc13 and Est1 in vitro

    Science.gov (United States)

    Chen, Yu-Fan; Lu, Chia-Ying; Lin, Yi-Chien; Yu, Tai-Yuan; Chang, Chun-Ping; Li, Jing-Ru; Li, Hung-Wen; Lin, Jing-Jer

    2016-01-01

    Telomerase is the enzyme involved in extending telomeric DNA. Control of telomerase activity by modulating its access to chromosome ends is one of the most important fundamental mechanisms. This study established an in vitro yeast telomerase reconstitution system that resembles telomere replication in vivo. In this system, a tailed-duplex DNA formed by telomeric DNA was employed to mimic the structure of telomeres. The core catalytic components of telomerase Est2/Tlc1 RNA were used as the telomeric DNA extension machinery. Using the reconstituted systems, this study found that binding of Cdc13 to telomeric DNA inhibited the access of telomerase to its substrate. The result was further confirmed by a single-molecule approach using the tethered-particle motion (TPM)-based telomerase assay. The findings also showed that the inhibitory effect can be relieved by telomerase-associated protein Est1, consistent with the role of Cdc13 and Est1 in regulating telomere extension in vivo. Significantly, this study found that the DNA binding property of Cdc13 was altered by Est1, providing the first mechanistic evidence of Est1 regulating the access of telomerase to its substrate. Thus, the roles of Cdc13 and Est1 in modulating telomerase activity were clearly defined using the in vitro reconstituted system. PMID:27659693

  2. 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.

  3. 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.

  4. Catalytically active telomerase holoenzyme is assembled in the dense fibrillar component of the nucleolus during S phase.

    Science.gov (United States)

    Lee, Ji Hoon; Lee, Yang Sin; Jeong, Sun Ah; Khadka, Prabhat; Roth, Jürgen; Chung, In Kwon

    2014-02-01

    The maintenance of human telomeres requires the ribonucleoprotein enzyme telomerase, which is composed of telomerase reverse transcriptase (TERT), telomerase RNA component, and several additional proteins for assembly and activity. Telomere elongation by telomerase in human cancer cells involves multiple steps including telomerase RNA biogenesis, holoenzyme assembly, intranuclear trafficking, and telomerase recruitment to telomeres. Although telomerase has been shown to accumulate in Cajal bodies for association with telomeric chromatin, it is unclear where and how the assembly and trafficking of catalytically active telomerase is regulated in the context of nuclear architecture. Here, we show that the catalytically active holoenzyme is initially assembled in the dense fibrillar component of the nucleolus during S phase. The telomerase RNP is retained in nucleoli through the interaction of hTERT with nucleolin, a major nucleolar phosphoprotein. Upon association with TCAB1 in S phase, the telomerase RNP is transported from nucleoli to Cajal bodies, suggesting that TCAB1 acts as an S-phase-specific holoenzyme component. Furthermore, depletion of TCAB1 caused an increase in the amount of telomerase RNP associated with nucleolin. These results suggest that the TCAB1-dependent trafficking of telomerase to Cajal bodies occurs in a step separate from the holoenzyme assembly in nucleoli. Thus, we propose that the dense fibrillar component is the provider of active telomerase RNP for supporting the continued proliferation of cancer and stem cells.

  5. 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.

  6. 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.

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

    DEFF Research Database (Denmark)

    Saeed, Hamid; Qiu, Weimin; Li, Chen

    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 (hMS...

  8. The telomerase inhibitor imetelstat alone, and in combination with trastuzumab, decreases the cancer stem cell population and self-renewal of HER2+ breast cancer cells.

    Science.gov (United States)

    Koziel, Jillian E; Herbert, Brittney-Shea

    2015-02-01

    Cancer stem cells (CSCs) are thought to be responsible for tumor progression, metastasis, and recurrence. HER2 overexpression is associated with increased CSCs, which may explain the aggressive phenotype and increased likelihood of recurrence for HER2(+) breast cancers. Telomerase is reactivated in tumor cells, including CSCs, but has limited activity in normal tissues, providing potential for telomerase inhibition in anti-cancer therapy. The purpose of this study was to investigate the effects of a telomerase antagonistic oligonucleotide, imetelstat (GRN163L), on CSC and non-CSC populations of HER2(+) breast cancer cell lines. The effects of imetelstat on CSC populations of HER2(+) breast cancer cells were measured by ALDH activity and CD44/24 expression by flow cytometry as well as mammosphere assays for functionality. Combination studies in vitro and in vivo were utilized to test for synergism between imetelstat and trastuzumab. Imetelstat inhibited telomerase activity in both subpopulations. Moreover, imetelstat alone and in combination with trastuzumab reduced the CSC fraction and inhibited CSC functional ability, as shown by decreased mammosphere counts and invasive potential. Tumor growth rate was slower in combination-treated mice compared to either drug alone. Additionally, there was a trend toward decreased CSC marker expression in imetelstat-treated xenograft cells compared to vehicle control. Furthermore, the observed decrease in CSC marker expression occurred prior to and after telomere shortening, suggesting that imetelstat acts on the CSC subpopulation in telomere length-dependent and -independent mechanisms. Our study suggests addition of imetelstat to trastuzumab may enhance the effects of HER2 inhibition therapy, especially in the CSC population.

  9. Inhibitory Effects of Selenium on Telomerase Activity and hTERT Expression in Cadmium-transformed 16HBE Cells

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Objective To investigate the effects of sodium selenite on telomerase activity and expression of hTERT mRNA in cadmium-transformed 16HBE cells. Methods Telomerase activity and expression of genes were measured after cultured cadmium-transformed 16HBE cells were exposed to sodium selenite at different doses (0.625, 1.25, 2.50, 5.00 μmol/L) for 24 hours. Results Selenium decreased telomerase activity in cadmium-transformed 16HBE cells. There existed an obvious dose-effect relationship between the selenium concentration and these changes. The expression of hTERT and c-myc mRNA also decreased but the expression of mad1 mRNA increased after exposure to selenium for 24 hours. No difference was found in expression of hTRF1 and hTRF2 mRNA after incubated with sodium selenite for 24 hours, compared with control group.Conclusion Selenium inhibits telomerase activity by decreasing hTERT and c-myc mRNA expression and increasing mad1 mRNA expression in cadmium-transformed 16HBE cells and selenium concentration is significantly correlated with these changes.

  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 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.

  12. Elevated telomerase activity in essential thrombocythemia with extreme thrombocytosis.

    Science.gov (United States)

    Kim, Miyoung; Oh, Bora; Kim, Tae Young; Yoon, Sung-Soo; Kim, Seon Young; Hwang, Sang Mee; Lee, Dong Soon

    2014-04-01

    We performed a comparative analysis of telomerase activity (TA) in patients with myeloproliferative neoplasm (MPN) and myelodysplastic syndrome (MDS). The relationships between TA and known prognostic factors were also analyzed. A telomeric repeat amplification protocol was performed with bone marrow hematopoietic cells from 96 normal controls, 44 MPNs, and 40 MDSs. TA (measured as molecules/reaction) showed no correlation with age in the control group (R(2)=0.0057, p=0.464). MPN showed elevated TA compared with controls (15,537.57 vs. 7775.44, p=0.020). Patients with essential thrombocythemia showed markedly elevated TA (22,688.56, p=0.030), particularly in cases with extreme thrombocytosis versus those without extreme thrombocytosis (34,522.19 vs. 9375.71, p=0.041). MDS patients showed a TA value of 7578.50. There was no association between age and TA in bone marrow hematopoietic cells. TA was elevated in MPN but borderline in MDS, probably because of differences in the nature of the diseases. Elevated TA in patients with essential thrombocythemia, especially those with extreme thrombocytosis, suggests that an anti-telomerase strategy could be beneficial in the prevention of thrombotic complications. Copyright © 2014. Published by Elsevier Inc.

  13. A novel telomerase activator suppresses lung damage in a murine model of idiopathic pulmonary fibrosis.

    Science.gov (United States)

    Le Saux, Claude Jourdan; Davy, Philip; Brampton, Christopher; Ahuja, Seema S; Fauce, Steven; Shivshankar, Pooja; Nguyen, Hieu; Ramaseshan, Mahesh; Tressler, Robert; Pirot, Zhu; Harley, Calvin B; Allsopp, Richard

    2013-01-01

    The emergence of diseases associated with telomere dysfunction, including AIDS, aplastic anemia and pulmonary fibrosis, has bolstered interest in telomerase activators. We report identification of a new small molecule activator, GRN510, with activity ex vivo and in vivo. Using a novel mouse model, we tested the potential of GRN510 to limit fibrosis induced by bleomycin in mTERT heterozygous mice. Treatment with GRN510 at 10 mg/kg/day activated telomerase 2-4 fold both in hematopoietic progenitors ex vivo and in bone marrow and lung tissue in vivo, respectively. Telomerase activation was countered by co-treatment with Imetelstat (GRN163L), a potent telomerase inhibitor. In this model of bleomycin-induced fibrosis, treatment with GRN510 suppressed the development of fibrosis and accumulation of senescent cells in the lung via a mechanism dependent upon telomerase activation. Treatment of small airway epithelial cells (SAEC) or lung fibroblasts ex vivo with GRN510 revealed telomerase activating and replicative lifespan promoting effects only in the SAEC, suggesting that the mechanism accounting for the protective effects of GRN510 against induced lung fibrosis involves specific types of lung cells. Together, these results support the use of small molecule activators of telomerase in therapies to treat idiopathic pulmonary fibrosis.

  14. A novel telomerase activator suppresses lung damage in a murine model of idiopathic pulmonary fibrosis.

    Directory of Open Access Journals (Sweden)

    Claude Jourdan Le Saux

    Full Text Available The emergence of diseases associated with telomere dysfunction, including AIDS, aplastic anemia and pulmonary fibrosis, has bolstered interest in telomerase activators. We report identification of a new small molecule activator, GRN510, with activity ex vivo and in vivo. Using a novel mouse model, we tested the potential of GRN510 to limit fibrosis induced by bleomycin in mTERT heterozygous mice. Treatment with GRN510 at 10 mg/kg/day activated telomerase 2-4 fold both in hematopoietic progenitors ex vivo and in bone marrow and lung tissue in vivo, respectively. Telomerase activation was countered by co-treatment with Imetelstat (GRN163L, a potent telomerase inhibitor. In this model of bleomycin-induced fibrosis, treatment with GRN510 suppressed the development of fibrosis and accumulation of senescent cells in the lung via a mechanism dependent upon telomerase activation. Treatment of small airway epithelial cells (SAEC or lung fibroblasts ex vivo with GRN510 revealed telomerase activating and replicative lifespan promoting effects only in the SAEC, suggesting that the mechanism accounting for the protective effects of GRN510 against induced lung fibrosis involves specific types of lung cells. Together, these results support the use of small molecule activators of telomerase in therapies to treat idiopathic pulmonary fibrosis.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Telomerase Activity Detected by Quantitative Assay in Bladder Carcinoma and Exfoliated Cells in Urine

    Directory of Open Access Journals (Sweden)

    Roberta Fedriga

    2001-01-01

    Full Text Available Early diagnosis is one of the most determining factors for patient survival. The detection of telomerase activity is a potentially promising tool in the diagnosis of bladder and other types of cancer due to the high expression of this enzyme in tumor cells. We carried out a quantitative evaluation of telomerase activity in urine samples in an attempt to determine a cut-off capable of identifying cancer patients. Telomerase activity was quantified by fluorescence TRAP assay in urine from 50 healthy volunteers and in urine and bioptic tumor samples from 56 previously untreated bladder cancer patients and expressed in arbitrary enzymatic units (AEU. Telomerase activity in urine ranged from 0 to 106 AEU (median 0 in healthy donors and from 0 to 282 AEU (median 87 in patients with cancer. A telomerase expression higher than the cut off value determined by receiver operating characteristic (ROC analysis was observed in 78% of cases, regardless of tumor grade and in 71% (15/21 of cases of nonassessable or negative cytology. The quantitative analysis of telomerase activity in urine enabled us to define cut-off values characterized by different sensitivity and specificity. Cytologic and telomerase determination, used sequentially, enabled us to detect about 90% of tumors.

  1. 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.

  2. 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 th...

  3. Impact of Arsenic Trioxide on LS-174T Cell Growth in vitro and the Activity of Telomerase

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The therapeutic action of arsenic trioxide( As2O3 ) on solid tumors has aroused widespread interest among scholars. To study the impact of As2 O3 on human colorectal carcinoma cells( LS-174T cell) and the activity of telomerase,the methods of PCR-ELISA, flow cytometry (FCM) and MTT assay in vitro were utilized. The results show that ( 1 ) with an increase in the concentration of As2 O3, the ratio of living the cells to dead cells decreases significantly,and the IC50 value is 5. 23 μg/mL; (2) the cells of the experimental groups can endure a series of morphological changes similar to the features of apoptosis; (3) the apoptotic curves of FCM pictures appear after 24 h, and the cells show the apoptosis in a time-dependent manner; (4) As2O3 can inhibit the activity of telomerase of the cell extraction obviously in a concentration-dependent and time-dependent manner after 24 h. It can be concluded from the experiment results in vitro that As2O3 can induce the apoptosis of LS-174T cells and inhibit the telomerase activity. Therefore, it has been proposed, for the first time, that these two factors( the apoptosis of LS-174T cells and the inhibition to the telomerase activity) are important causes of the LS-174T cell death caused by As2O3.

  4. Anti-HIV-1 Activities of 4 Telomerase Restrictors

    Institute of Scientific and Technical Information of China (English)

    YU Xin; WANG Jinghui; de Giuli Morghen; Radaelli A; Zanotto C; Beggio P

    2007-01-01

    MTT Cell Proliferation Assay was used to optimize the concentration of Telomerase Restrictors(TRs) with minimum toxicity to the selected cells. FACSort flow cytometer and Innotest P24 HIV(Human immunodeficiency Virus) antigen mAb ELISA Kit were used to investigate the anti-HIV-1 activities of TRs. The results showed that TRs had low cytotoxicity to the PBMC (Peripheral Blood mononuclear cells) and CEM/GFP if the concentration of TRs was at 50 μmol/L or below, and the supernatant from PBMC pretreated with SHIV and TR1-001 /TR1-002 could not infect the PBMC, while can infect the C8166 with reduced infectivity, which suggested that the TRs may be one of the novel resources for screening anti-HIV-1 agents.

  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.

  6. 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.

  7. Troglitazone suppresses telomerase activity independently of PPAR? in estrogen-receptor negative breast cancer cells

    OpenAIRE

    Nguyen Johnny; Taboski Michael AS; Rashid-Kolvear Fariborz; Wang Dong-Yu; Harrington Lea A; Done Susan J

    2010-01-01

    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 telom...

  8. POT1a and components of CST engage telomerase and regulate its activity in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Kyle B Renfrew

    2014-10-01

    Full Text Available Protection of Telomeres 1 (POT1 is a conserved nucleic acid binding protein implicated in both telomere replication and chromosome end protection. We previously showed that Arabidopsis thaliana POT1a associates with the TER1 telomerase RNP, and is required for telomere length maintenance in vivo. Here we further dissect the function of POT1a and explore its interplay with the CST (CTC1/STN1/TEN1 telomere complex. Analysis of pot1a null mutants revealed that POT1a is not required for telomerase recruitment to telomeres, but is required for telomerase to maintain telomere tracts. We show that POT1a stimulates the synthesis of long telomere repeat arrays by telomerase, likely by enhancing repeat addition processivity. We demonstrate that POT1a binds STN1 and CTC1 in vitro, and further STN1 and CTC1, like POT1a, associate with enzymatically active telomerase in vivo. Unexpectedly, the in vitro interaction of STN1 with TEN1 and POT1a was mutually exclusive, indicating that POT1a and TEN1 may compete for the same binding site on STN1 in vivo. Finally, unlike CTC1 and STN1, TEN1 was not associated with active telomerase in vivo, consistent with our previous data showing that TEN1 negatively regulates telomerase enzyme activity. Altogether, our data support a two-state model in which POT1a promotes an extendable telomere state via contacts with the telomerase RNP as well as STN1 and CTC1, while TEN1 opposes these functions.

  9. Telomerase activity in solid transitional cell carcinoma, bladder washings, and voided urine.

    Science.gov (United States)

    Lance, R S; Aldous, W K; Blaser, J; Thrasher, J B

    1998-03-04

    Telomerase activity has been detected in a wide variety of human malignancies. It appears to be one of the fundamental ingredients necessary for cellular immortality. We sought to determine the incidence of telomerase activity in solid transitional cell carcinoma (TCC) specimens, benign urothelium, bladder washings, and voided urine from patients with TCC identified cystoscopically compared with controls. Telomerase activity was measured in 26 solid bladder cancers and 13 benign urothelial specimens using the telomere repeat amplification protocol (TRAP), a polymerase chain reaction (PCR) based assay. Telomerase activity was further measured in the centrifuged cellular material obtained from the bladder washings of 26 patients with TCC and 40 with benign urologic disease found to have a normal cystoscopy. All patients with hematuria were additionally evaluated with an upper tract radiographic examination and found to be free of malignancy. Voided urine was likewise evaluated in 11 patients with TCC, 12 with benign urologic diseases, and 56 asymptomatic control subjects. Telomerase activity was detected in 25 of 26 (96%) solid specimens, 21 of 26 (81%) bladder washings, and 6 of 11 (54%) voided urine specimens from patients with histologically confirmed TCC. In the control group, 2 of 13 (15%) benign urothelial specimens and 2 of 56 (4%) voided urine specimens from the asymptomatic volunteer group demonstrated telomerase activity. Of those with benign urologic disease, 16 of 40 (40%) bladder barbotage specimens and 6 of 12 (50%) voided urine specimens demonstrated telomerase activity. Sensitivity and specificity of telomerase as a marker for TCC were 81% and 60%, respectively, in the bladder washings group and 54% and 50%, respectively, in voided urine. These data indicate that activation of telomerase is frequent in solid TCC and appears to be a sensitive marker in bladder washings of patients with TCC. We noted an unexpectedly high false positive detection rate in

  10. Telomerase inhibitory effects of medicinal mushrooms and lichens, and their anticancer activity.

    Science.gov (United States)

    Xu, Baojun; Li, Chantian; Sung, Changkeun

    2014-01-01

    Telomerase has been widely accepted as a cancer marker and a promising therapeutic target for novel anticancer drugs. The aim of this study was to investigate the in vitro telomerase inhibitory effects of mushrooms and their anticancer properties. The inhibitory effects of mushrooms and lichens against telomerase activity of HL-60 cells were systematically assessed using polymerase chain reaction based on assay of telomeric repeat amplification protocol. Telomerase inhibitory samples were further tested for antiproliferation effects against the gastric cell line SNU-1 using the MTT method. Ethyl acetate extract of Pleurotus ostreatus, ethyl acetate and water extracts of Lasiosphaera fenzlii, hexane extract of Strobilomyces floccopus, water extract of Sarcodon aspratus, and hexane, ethyl acetate, and water extracts from Umbilicaria esculenta showed strong positive telomerase inhibitory activity. Hexane extract of S. floccopus and water extracts from the edible lichen U. esculenta exhibited strong anticancer effects against SNU-1 cells through antiproliferation assay. The water extract of U. esculenta has a great potential to be developed into an anticancer agent that targets telomerase.

  11. Analysis of telomerase activity based on a spired DNA tetrahedron TS primer.

    Science.gov (United States)

    Li, Yan; Wen, Yanli; Wang, Lele; Liang, Wen; Xu, Li; Ren, Shuzhen; Zou, Ziying; Zuo, Xiaolei; Fan, Chunhai; Huang, Qing; Liu, Gang; Jia, Nengqin

    2015-05-15

    The development of sensitive telomerase biosensors is hindered by the restricted accessibility of telomere strand (TS) primer and the limited enzyme reaction space, which is mainly confined by the vertical distance. In this work, we designed an electrochemical telomerase biosensor based on a spired DNA tetrahedron TS primer (STTS). By adding a rigid dsDNA spire onto the top of the DNA tetrahedron, we successfully regulated the distance between the TS primer and the surface, and thus greatly facilitated the telomerase elongation on surface. The signal-to-noise ratio was 2 times higher than TSP without the spire structure. The limit of detection was calculated to be lower than 10 HeLa cells, which is at least 2 magnitudes lower than other surface extension-based electrochemical telomerase sensors without amplification. The practicability of STTS sensor was also demonstrated by analysing various other cell lines including cancer cells, stem cells of high telomerase activity and somatic cells of low telomerase activity.

  12. Completion of cell division is associated with maximum telomerase activity in naturally synchronized cultures of the green alga Desmodesmus quadricauda.

    Science.gov (United States)

    Ševčíková, Tereza; Bišová, Kateřina; Fojtová, Miloslava; Lukešová, Alena; Hrčková, Kristýna; Sýkorová, Eva

    2013-03-18

    Telomerase maintains the ends of eukaryotic chromosomes, and its activity is an important parameter correlating with the proliferative capacity of cells. We have investigated cell cycle-specific changes in telomerase activity using cultures of Desmodesmus quadricauda, a model alga naturally synchronized by light/dark entrainment. A quantitative telomerase assay revealed high activity in algal cultures, with slight changes during the light period. Significantly increased telomerase activity was observed at the end of the dark phase, when cell division was complete. In contrast to other models, a natural separation between nuclear and cellular division typical for the cell cycle in D. quadricauda made this observation possible.

  13. 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.

  14. Salinomycin Abolished STAT3 and STAT1 Interactions and Reduced Telomerase Activity in Colorectal Cancer Cells.

    Science.gov (United States)

    Chung, Seyung S; Adekoya, Debbie; Enenmoh, Ikechukwu; Clarke, Orette; Wang, Piwen; Sarkyssian, Marianna; Wu, Yong; Vadgama, Jaydutt V

    2017-02-01

    Colorectal cancer is the third leading cause of cancer-related mortality in most developed countries. This mortality is mainly due to the metastatic progression to the liver with frequent recurrence. Colorectal cancer remains a therapeutic challenge and this has intensified the search for new drug targets. In an effort to establish a novel targeted-therapy, we studied the molecular mechanisms of cancer stem cell inhibitor salinomycin. Co-immunoprecipitation was performed to examine STAT3-STAT1 protein interactions. Telomerase activity was measured by polymerase chain reaction (PCR) and ELISA assays. Apoptosis and cell stress arrays were analyzed to identify key proteins responding to salinomycin treatments. IL-6 and TNF-α induced STAT3 and STAT1 interactions, however the interactions were abolished by salinomycin challenge. Salinomycin reduced cancer stem cell phenotype and decreased telomerase activity of colorectal cancer cells. Our work uncovers a new mechanism through which salinomycin inhibits cancer stemness suggesting a novel targeted-therapy for metastatic colorectal cancer. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  15. Telomerase activity in patients with stage 2-5D chronic kidney disease.

    Science.gov (United States)

    Kidir, Veysel; Aynali, Ayse; Altuntas, Atila; Inal, Salih; Aridogan, Buket; Sezer, Mehmet Tugrul

    2017-07-10

    Molecular mechanisms of increased cardiovascular mortality in chronic kidney disease (CKD) associated with biological age are not well understood. Recent studies support the hypothesis that common factors responsible for this phenomenon are cellular aging and telomere dysfunction. The purpose of this study was to investigate the relation between telomerase activity and CKD stages. The study included 120 patients who were followed-up for CKD stage 2-5D, composed of 30 patients of each stage and 30 healthy volunteers without any known disease who were admitted to our hospital for routine check-ups. Telomerase activity in peripheral blood mononuclear cells (PBMC) was measured using the TRAP assay. A significant difference was observed for telomerase activity in PBMC between groups. The detected levels were lowest in the healthy control group (0.15±0.02), and highest in CKD stage 5D patients (0.23±0.04). In CKD patients, telomerase activity in PBMC was positively correlated with the CKD stage, serum creatinine, potassium and parathormone levels, and negatively correlated with estimated glomerular filtration rate (eGFR), body mass index (BMI), platelet count and serum calcium levels. According to the linear regression analysis, independent predictors for high telomerase activity in CKD patients were eGFR and BMI. Telomerase activity in PBMC increases with advancing CKD stage in CKD patients. Increased telomerase activity in PBMC is associated with eGFR and BMI. Copyright © 2017 Sociedad Española de Nefrología. Published by Elsevier España, S.L.U. All rights reserved.

  16. 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

    , and 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...

  17. CpG island methylator phenotype association with upregulated telomerase activity in hepatocellular carcinoma.

    Science.gov (United States)

    Zhang, Changsong; Guo, Xianling; Jiang, Guocheng; Zhang, Li; Yang, Yang; Shen, Feng; Wu, Mengchao; Wei, Lixin

    2008-09-01

    CpG island methylator phenotype (CIMP) involves the targeting of multiple genes by promoter hypermethylation. Telomerase plays an important role in the development of cellular immortality and oncogenesis. To gain insight into the role of epigenetic aberration of telomerase-related genes in hepatocarcinogenesis, we determined a hypermethylation profile in HCC. We examined the promoter methylation status of 9 genes associated with telomerase activity in 120 HCC, 120 cirrhosis tissues and 10 normal liver tissues by methylation-specific PCR. Assay of telomerase activity was by TRAP-ELISA. The frequency of promoter methylation of each gene was P21 63.3%, P15 42.5%, P16 62.5%, P53 14.2%, RB 32.5%, P27 48.3%, WTI 54.2%, E2F-1 70.8% and P300 65.8% of 120 HCC. Methylation status of P21, P15, P16, WTI and E2F-1 was significantly associated with HCC and nontumor tissues (p < 0.05). CIMP+ was detected in 61.7% (74/120) HCC and 15% (18/120) cirrhosis tissues, no CIMP+ was present in normal liver tissues (p < 0.001). A significant difference between CIMP status and metastasis was been found in HCC (p < 0.001). Results showed that 94.6% (70/74) HCC and 55.6% (10/18) cirrhosis patients with CIMP+ show expression of high telomerase activity than 45.5% (10/22) HCC and 6.25% (1/16) cirrhosis patients with CIMP- (p < 0.001). CIMP lead to high levels of expression of telomerase activity through the simultaneous inactivation of multiple genes associated with telomerase activity by concordant methylation.

  18. 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.

  19. 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.

  20. Inhibition of cell growth and telomerase activity in osteosarcoma cells by DN-hTERT.

    Science.gov (United States)

    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), (PDN-hTERT-expressing clones did not form tumors in 2 weeks, but the ratio of tumorigenesis was 30 % in nude mice bearing MG63/I (PDN-hTERT could specifically inhibit the cell growth and telomerase activity in MG63 cells.

  1. 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.

  2. Clinical Relevance of Telomere Status and Telomerase Activity in Colorectal Cancer.

    Science.gov (United States)

    Fernández-Marcelo, Tamara; Sánchez-Pernaute, Andrés; Pascua, Irene; De Juan, Carmen; Head, Jacqueline; Torres-García, Antonio-José; Iniesta, Pilar

    2016-01-01

    The role of telomeres and telomerase in colorectal cancer (CRC) is well established as the major driving force in generating chromosomal instability. However, their potential as prognostic markers remains unclear. We investigated the outcome implications of telomeres and telomerase in this tumour type. We considered telomere length (TL), ratio of telomere length in cancer to non-cancer tissue (T/N ratio), telomerase activity and TERT levels; their relation with clinical variables and their role as prognostic markers. We analyzed 132 CRCs and paired non-cancer tissues. Kaplan-Meier curves for disease-free survival were calculated for TL, T/N ratio, telomerase activity and TERT levels. Overall, tumours had shorter telomeres than non-tumour tissues (P Telomere lengths of non-tumour tissues and CRCs were positively correlated (P telomere status and clinical variables, the lowest degree of telomere shortening was shown by tumours located in the rectum (P = 0.021). Regarding prognosis studies, patients with tumours showing a mean TL telomere shortening relapsed during the follow-up period (P = 0.043). The mean TL in CRCs emerged as an independent prognostic factor in the Cox analysis (P = 0.017). Telomerase-positive activity was identified as a marker that confers a trend toward a poor prognosis. In CRC, our results support the use of telomere status as an independent prognostic factor. Telomere status may contribute to explaining the different molecular identities of this tumour type.

  3. 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.

  4. Immunocalization of telomerase in cells of lizard tail after amputation suggests cell activation for tail regeneration.

    Science.gov (United States)

    Alibardi, L

    2016-02-01

    Tail amputation (autotomy) in most lizards elicits a remarkable regenerative response leading to a new although simplified tail. No information on the trigger mechanism following wounding is known but cells from the stump initiate to proliferate and form a regenerative blastema. The present study shows that telomerases are mainly activated in the nuclei of various connective and muscle satellite cells of the stump, and in other tissues, probably responding to the wound signals. Western blotting detection also indicates that telomerase positive bands increases in the regenerating blastema in comparison to the normal tail. Light and ultrastructural immunocytochemistry localization of telomerase shows that 4-14 days post-amputation in lizards immunopositive nuclei of sparse cells located among the wounded tissues are accumulating into the forming blastema. These cells mainly include fibroblasts and fat cells of the connective tissue and satellite cells of muscles. Also some immature basophilic and polychromatophilic erytroblasts, lymphoblasts and myelocytes present within the Bone Marrow of the vertebrae show telomerase localization in their nuclei, but their contribution to the formation of the regenerative blastema remains undetermined. The study proposes that one of the initial mechanisms triggering cell proliferation for the formation of the blastema in lizards involve gene activation for the production of telomerase that stimulates the following signaling pathways for cell division and migration.

  5. TRAP-silver staining, a highly sensitive assay for measuring telomerase activity in tumor tissue and cell lines

    Directory of Open Access Journals (Sweden)

    C.A. Dalla Torre

    2002-01-01

    Full Text Available Measurement of telomerase activity in clinically obtained tumor samples may provide important information for use as both a diagnostic marker and a prognostic indicator for patient outcome. In order to evaluate telomerase activity in tumor tissue without radiolabeling the product, we developed a simple telomeric repeat amplification protocol-silver-staining assay that is less time-consuming, is safe and requires minimal equipment. In addition, we determined the sensitivity of the silver-staining method by using extracts of telomerase-positive thyroid carcinoma cell lines which were serially diluted from 5,000 to 10 cells. Telomerase activity was also assayed in 19 thyroid tumors, 2 normal controls and 27 bone marrow aspirates. The results indicate that the technique permits the detection of telomerase activity from 5000 to as few as 10 cells. We propose that it could be immediately applicable in many laboratories due to the minimal amount of equipment required.

  6. Inhibition of telomerase activity preferentially targets aldehyde dehydrogenase-positive cancer stem-like cells in lung cancer

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    Iniesta Pilar

    2011-08-01

    Full Text Available Abstract Background Mortality rates for advanced lung cancer have not declined for decades, even with the implementation of novel chemotherapeutic regimens or the use of tyrosine kinase inhibitors. Cancer Stem Cells (CSCs are thought to be responsible for resistance to chemo/radiotherapy. Therefore, targeting CSCs with novel compounds may be an effective approach to reduce lung tumor growth and metastasis. We have isolated and characterized CSCs from non-small cell lung cancer (NSCLC cell lines and measured their telomerase activity, telomere length, and sensitivity to the novel telomerase inhibitor MST312. Results The aldehyde dehydrogenase (ALDH positive lung cancer cell fraction is enriched in markers of stemness and endowed with stem cell properties. ALDH+ CSCs display longer telomeres than the non-CSC population. Interestingly, MST312 has a strong antiproliferative effect on lung CSCs and induces p21, p27 and apoptosis in the whole tumor population. MST312 acts through activation of the ATM/pH2AX DNA damage pathway (short-term effect and through decrease in telomere length (long-term effect. Administration of this telomerase inhibitor (40 mg/kg in the H460 xenograft model results in significant tumor shrinkage (70% reduction, compared to controls. Combination therapy consisting of irradiation (10Gy plus administration of MST312 did not improve the therapeutic efficacy of the telomerase inhibitor alone. Treatment with MST312 reduces significantly the number of ALDH+ CSCs and their telomeric length in vivo. Conclusions We conclude that antitelomeric therapy using MST312 mainly targets lung CSCs and may represent a novel approach for effective treatment of lung cancer.

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

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    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.

  8. Amplification of hTERT and hTERC genes in leukemic cells with high expression and activity of telomerase.

    Science.gov (United States)

    Nowak, Tomasz; Januszkiewicz, Danuta; Zawada, Mariola; Pernak, Monika; Lewandowski, Krzysztof; Rembowska, Jolanta; Nowicka, Karina; Mankowski, Przemyslaw; Nowak, Jerzy

    2006-08-01

    Reactivation of telomerase plays an important role in carcinogenesis. Malignant cells almost always possess high activity and expression of telomerase. The aim of this study was to see whether there is any relationship between telomerase activity and expression and hTERT and hTERC gene amplification in acute lymphoblastic leukemia (ALL) and non-lymphoblastic leukemia (ANLL) cells. In addition telomere length was tested in leukemic cells at the time of diagnosis and during remission. Expression of the three components of telomerase (hTERT, hTERC and TP1) as well as telomerase activity was found both in ALL and ANLL cells. Telomerase activity was diminished in patients in remission. The leukemic cells showed considerable heterogeneity of terminal restriction fragments, that is telomere length. ALL cells showed a variable pattern of telomere length in contrast to ANLL cells which produced a predominantly short telomere pattern. Telomere length in the lymphocytes of leukemia patients was shorter in remission as compared to the time of diagnosis. FISH analysis revealed amplification of hTERT and hTERC genes in ALL and ANLL cells. Quantitative analysis showed that leukemic cells possess higher number of hTERT and hTERC copies than the normal PBL. Our results suggest that the activation of telomerase in leukemic cells is connected with amplification of hTERT and hTERC genes. The high expression and activity of telomerase found in leukemic cells may be partially explained by amplified hTERT and hTERC genes. Amplification of the telomerase genes seems to be a common event in carcinogenesis and may play a role in telomerase reactivation leading to cell immortalization.

  9. 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

  10. 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

  11. 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

  12. 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

  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. Telomerase activity and telomere length in human tumor cells with acquired resistance to anticancer agents.

    Science.gov (United States)

    Smith, V; Dai, F; Spitz, M; Peters, G J; Fiebig, H H; Hussain, A; Burger, A M

    2009-11-01

    Telomeres and telomerase are targets for anticancer drug development and specific inhibitors are currently under clinical investigation. However, it has been reported that standard cytotoxic agents can affect telomere length and telomerase activity suggesting that they also have of a role in drug resistance. in this study, telomere lengths and telomerase activity as well as drug efflux pump expression, glutathione (GSH) levels and polyadenosine-ribose polymerase (PARP) cleavage were assessed in a panel of human tumor cell lines made resistant to vindesine, gemcitabine and cisplatin. these included two lung cancer cell lines resistant to vindesine (LXFL 529L/Vind, LXFA 526L/Vind), a renal cancer cell line (RXF944L/Gem) and an ovarian cancer cell line (AG6000) resistant to gemcitabine, and one resistant to cisplatin (ADDP). The resistant clones were compared to their parental lines and evaluated for cross resistance to other cytotoxic agents. Several drug specific resistance patterns were found, and various complex patterns of cross resistance emerged from some cell lines, but these mechanisms of resistance could not be related to drug efflux pump expression, GSH levels or pARp cleavage. However, all displayed changes in telomerase activity and/or telomere length. Our studies present evidence that telomere maintenance should be taken into consideration in efforts not only to overcome drug resistance, but also to optimize the use of telomere-based therapeutics.

  15. 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.

  16. Contribution of Sp1 to Telomerase Expression and Activity in Skin Keratinocytes Cultured With a Feeder Layer.

    Science.gov (United States)

    Bisson, Francis; Paquet, Claudie; Bourget, Jean-Michel; Zaniolo, Karine; Rochette, Patrick J; Landreville, Solange; Damour, Odile; Boudreau, François; Auger, François A; Guérin, Sylvain L; Germain, Lucie

    2015-02-01

    The growth of primary keratinocytes is improved by culturing them with a feeder layer. The aim of this study was to assess whether the feeder layer increases the lifespan of cultured epithelial cells by maintaining or improving telomerase activity and expression. The addition of an irradiated fibroblast feeder layer of either human or mouse origin (i3T3) helped maintain telomerase activity as well as expression of the transcription factor Sp1 in cultured keratinocytes. In contrast, senescence occurred earlier, together with a reduction of Sp1 expression and telomerase activity, in keratinocytes cultured without a feeder layer. Telomerase activity was consistently higher in keratinocytes grown on the three different feeder layers tested relative to cells grown without them. Suppression of Sp1 expression by RNA inhibition (RNAi) reduced both telomerase expression and activity in keratinocytes and also abolished their long-term growth capacity suggesting that Sp1 is a key regulator of both telomerase gene expression and cell cycle progression of primary cultured human skin keratinocytes. The results of the present study therefore suggest that the beneficial influence of the feeder layer relies on its ability to preserve telomerase activity in cultured human keratinocytes through the maintenance of stable levels of Sp1 expression. © 2014 Wiley Periodicals, Inc.

  17. 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.

  18. 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.

  19. Fucoidan Induces ROS-Dependent Apoptosis in 5637 Human Bladder Cancer Cells by Downregulating Telomerase Activity via Inactivation of the PI3K/Akt Signaling Pathway.

    Science.gov (United States)

    Han, Min Ho; Lee, Dae-Sung; Jeong, Jin-Woo; Hong, Su-Hyun; Choi, Il-Whan; Cha, Hee-Jae; Kim, Suhkmann; Kim, Heui-Soo; Park, Cheol; Kim, Gi-Young; Moon, Sung-Kwon; Kim, Wun-Jae; Hyun Choi, Yung

    2017-02-01

    Preclinical Research Fucoidan, a sulfated polysaccharide, is a compound found in various species of seaweed that has anti-viral, anti-bacterial, anti-oxidant, anti-inflammatory, and immunomodulatory activities; however, the underlying relationship between apoptosis and anti-telomerase activity has not been investigated. Here, we report that fucoidan-induced apoptosis in 5637 human bladder cancer cells was associated with an increase in the Bax/Bcl-2 ratio, the dissipation of the mitochondrial membrane potential (MMP, Δψm), and cytosolic release of cytochrome c from the mitochondria. Under the same experimental conditions, fucoidan-treatment decreased hTERT (human telomerase reverse transcriptase) expression and the transcription factors, c-myc and Sp1. This was accompanied by decreased telomerase activity. Fucoidan-treatment also suppressed activation of the PI3K/Akt signaling pathway. Inhibition of PI3K/Akt signaling enhanced fucoidan-induced apoptosis and anti-telomerase activity. Meanwhile, fucoidan treatment increased the generation of intracellular ROS, whereas the over-elimination of ROS by N-acetylcysteine, an anti-oxidant, attenuated fucoidan-induced apoptosis, inhibition of hTERT, c-myc, and Sp1 expression, and reversed fucoidan-induced inactivation of the PI3K/Akt signaling pathway. Collectively, these data indicate that the induction of apoptosis and the inhibition of telomerase activity by fucoidan are mediated via ROS-dependent inactivation of the PI3K/Akt pathway. Drug Dev Res 78 : 37-48, 2017.   © 2016 Wiley Periodicals, Inc.

  20. Transcriptional activity of telomerase complex in CD34- stem cells of cord blood in dependence of preparation time.

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    M Bojdys-Szyndlar

    2009-12-01

    Full Text Available The aim of the study was to determine whether the expression of telomerase subunits encoding genes changes during the process of cord blood preparation. It should establish if the commonly accepted 24 hours time interval in stem cells kriopreservation procedure significantly influences their immortalization and so decreases the "quality" of cord blood stem cells. Investigation includes 69 women. Spontaneous labour was the inclusion condition. The material was collected at birth after clamping of umbilical cord by direct vasopuncture. CD34- cells were extracted from cord blood (MACS, Miltenyi Biotec; Bisley, Surrey, UK. The expression profile of telomerase activators and inhibitors encoding genes was determined using HG_U133A oligonucleotide microarray (Affymetrix. We used a real-time quantitative RT-PCR assay to quantify the telomerase TERT, hTR and TP1 subunits mRNA copy numbers in CD34- cells in 0, 6, 12 and 24 hours after cord blood collection. We observed significant decrease of numbers of copies of TERTA+B mRNA within the successive hours of observation. Significant decrease of numbers of TERTA mRNA copies was confirmed after 24 hours. However, we observed significant increase of numbers of copies of TERTB mRNA after 6 hours of observation. Similar level was maintained during another 6h. The significantly lower number of copies of TERTB mRNA was observed after 24h. We also observed significant increase of number of copies of TERT mRNA after 6 hours. Number of copies of TERT mRNA significantly decreased after another 6h, remaining, however, on a higher then initial one. The significant lower number of copies of TERT mRNA was observed 24h after delivery. The possible explanation of those results is discussed in the paper.

  1. Label-free molecular beacons-based cascade amplification DNA machine for sensitive detection of telomerase activity.

    Science.gov (United States)

    Li, Kan; Wang, Lei; Xu, Xiaowen; Jiang, Wei

    2017-05-15

    Sensitive detection of telomerase activity is critical to cancer diagnosis, screening of anticancer drugs and evaluation of cancer therapy. Herein, a label-free molecular beacons-based DNA machine was developed for sensitive detection of telomerase activity. The DNA machine consisted of T7 exonuclease (T7 Exo), label-free recognition molecular beacon (RMB) and signal molecular beacon (SMB) with projecting 5'-terminuses, which can protect RMB and SMB from being digested by T7 Exo. Firstly, telomerase elongated telomerase substrate (TS) primer, generating a telomerase elongation production (TEP) with tandem repeats (TTAGGG)n. Next, TEP activated the DNA machine by hybridizing with RMB, unfolding RMB with a recessed 5'-terminus, making RMB deprotection from T7 Exo. Then T7 Exo-assisted cycling cleavage was incurred, releasing intact TEP and numerous DNA fragments (trigger DNA), which got recycling I. Subsequently, trigger DNA specifically opened SMB and was recycled by T7 Exo, liberating multiple G-quadruplex (G4) structures, which got recycling II. Finally, TEP and the liberative G4 structures strongly interacted with N-methyl-mesoporphyrin IX (NMM), yielding a significantly enhanced fluorescence together. In this way, per telomerase-mediated elongation event was efficiently converted into the greatly amplified fluorescence signals. Telomerase activity in crude HeLa cells extracts equivalent to 50 cells/mL was successfully measured with a linear range from 50 cells/mL to 2000 cells/mL. Besides, the strategy was also successfully used to assay the inhibition effect of a telomerase-inhibiting drug, demonstrating the strategy holds the potential to screen telomerase inhibitors.

  2. 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.

  3. Clinical significance of telomerase activity in peritoneal lavage fluid from patients with gastric cancer and its relationship with cellular proliferation

    Institute of Scientific and Technical Information of China (English)

    Ming-Xu Da; Xiao-Ting Wu; Tian-Kang Guo; Zi-Guang Zhao; Ting Luo; Kun Qian; Ming-Ming Zhang; Jie Wang

    2007-01-01

    AIM: To evaluate the efficacy of telomerase activity assay and peritoneal lavage cytology (PLC) examination in peritoneal lavage fluid for the prediction of peritoneal metastasis in gastric cancer patients, and to explore the relationship between telomerase activity and proliferating cell nuclear antigen expression.METHODS: Telomeric repeated amplification protocol (TRAP)-enzyme-linked immunosorbent assay (ELISA) was performed to measure the telomerase activity in 60 patients with gastric cancer and 50 with peptic ulcer. PLC analysis of the 60 patients with gastric cancer was used for comparison. The proliferating cell nuclear antigen (PCNA) in gastric carcinoma was immunohistochemically examined.RESULTS: The telomerase activity and PLC positive rate in peritoneal lavage fluid from patients with gastric cancer was 41.7% (25/60), and 25.0% (15/60), respectively. The positive rate of telomerase activity was significantly higher than that of PLC in the group Of pT4 (15/16 vs 9/16, P < 0.05), P1-3 (13/13 vs 9/13, P < 0.05) and diffuse type (22/42 vs 13/42, P < 0.05). The patients with positive telomerase activity, peritoneal metastasis, and serosal invasion had significantly higher levels of average PCNA proliferation index (PI), (55.00 ± 6.59 vs 27.43 ± 7.72, 57.26 ± 10.18 vs 29.15 ± 8.31, and 49.82 ± 6.74 vs 24;65 ± 7.33, respectively, P < 0.05).CONCLUSION: The TRAP assay for telomerase activity is a useful adjunct for cytologic method in the diagnosis of peritoneal micrometastasis and well related to higher proliferating activity of gastric cancer. The results of this study also suggest a promising future therapeutic strategy for treating peritoneal dissemination based on telomerase inhibition.

  4. 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.

  5. Resveratrol-induced augmentation of telomerase activity delays senescence of endothelial progenitor cells

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-bin; ZHU Li; HUANG Jun; YIN Yi-gang; KONG Xiang-qing; RONG Qi-fei; SHI Ai-wu; CAO Ke-jiang

    2011-01-01

    Background Previous studies have shown that resveratrol increases endothelial progenitor cell (EPC) numbers and functional activity.Increased EPC numbers and activity are associated with the inhibition of EPC senescence.In this study,we investigated the effect of resveratrol on the senescence of EPCs,leading to potentiation of cellular function.Methods EPCs were isolated from human peripheral blood and identified immunocytochemically.EPCs were incubated with resveratrol (1,10,and 50 μmol/L) or control for specified times.After in vitro cultivation,acidic β-galactosidase staining revealed the extent of senescence in the cells.To gain further insight into the underlying mechanism of the effect of resveratrol,we measured telomerase activity using a polymerase chain reaction (PCR)-enzyme-linked immunosorbent assay (ELISA) technique.Furthermore,we measured the expression of human telomerase reverse transcriptase (hTERT) and the phosphorylation of Akt by immunoblotting.Results Resveratrol dose-dependently inhibited the onset of EPC senescence in culture.Resveratrol also significantly increased telomerase activity.Interestingly,quantitative real-time PCR analysis demonstrated that resveratrol dose-dependently increased the expression of the catalytic subunit,hTERT,an effect that was significantly inhibited by pharmacological phosphatidylinositol 3-kinase (PI3-K) blockers (wortmannin).The expression of hTERT is regulated by the PI3-K/Akt pathway; therefore,we examined the effect of resveratrol on Akt activity in EPCs.Immunoblotting analysis revealed that resveratrol led to dose-dependent phosphorylation and activation of Akt in EPCs.Conclusion Resveratrol delayed EPCs senescence in vitro,which may be dependent on telomerase activation.

  6. Therapeutic Targeting of Telomerase

    Directory of Open Access Journals (Sweden)

    Kathrin Jäger

    2016-07-01

    methods, and personalized approaches. Telomerase activation and cell rejuvenation is successfully used in regenerative medicine for tissue engineering and reconstructive surgery. However, there are also a number of pitfalls in the treatment with telomerase activating procedures for the whole organism and for longer periods of time. Extended cell lifespan may accumulate rare genetic and epigenetic aberrations that can contribute to malignant transformation. Therefore, novel vector systems have been developed for a ‘mild’ integration of telomerase into the host genome and loss of the vector in rapidly-proliferating cells. It is currently unclear if this technique can also be used in human beings to treat chronic diseases, such as atherosclerosis.

  7. [Suppression of telomerase activity leukemic cells by mutant forms of Rhodospirillum rubrum L-asparaginase].

    Science.gov (United States)

    Pokrovskaya, M V; Zhdanov, D D; Eldarov, M A; Aleksandrova, S S; Veselovskiy, A V; Pokrovskiy, V S; Grishin, D V; Gladilina, Ju A; Sokolov, N N

    2017-01-01

    The active and stable mutant forms of short chain cytoplasmic L-asparaginase type I of Rhodospirillum rubrum (RrA): RrA+N17, D60K, F61L, RrA+N17, A64V, E67K, RrA+N17, E149R, V150P, RrAE149R, V150P and RrAE149R, V150P, F151T were obtained by the method of site-directed mutagenesis. It is established that variants RrA-N17, E149R, V150P, F151T and RrАE149R, V150P are capable to reduce an expression hTERT subunit of telomerase and, hence, activity of telomeres in Jurkat cells, but not in cellular lysates. During too time, L-asparaginases of Escherichia coli, Erwinia carotovora and Wolinella succinogenes, mutant forms RrА+N17, D60K, F61L and RrА+N17, A64V, E67K do not suppress of telomerase activity. The assumption of existence in structure RrA of areas (amino acids residues in the position 146-164, 1-17, 60-67) which are responsible for suppression of telomerase activity is made. The received results show that antineoplastic activity of some variants RrA is connected both with reduction of concentration of free L-asparagine, and with expression suppression of hTERT telomerase subunit, that opens new prospects for antineoplastic therapy.

  8. TCAB1: driving telomerase to Cajal bodies.

    Science.gov (United States)

    Venteicher, Andrew S; Artandi, Steven E

    2009-05-01

    Telomerase supports the proliferation of progenitor cells and tumor cells by adding telomere repeats to chromosome ends. The low abundance and restricted expression pattern of telomerase have limited our knowledge of this important enzyme. A new telomerase protein, TCAB1, sheds light on the pathway that governs telomerase holoenzyme assembly and function in vivo. TCAB1 is a component of active telomerase and is required for the telomerase holoenzyme to accumulate in Cajal bodies and to elongate telomeres. These findings provide important new insights into how telomerase functions in cancer and in stem cell biology.

  9. The hypothetical ancestral animal. the Urmetazoa: telomerase activity in sponges (Porifera

    Directory of Open Access Journals (Sweden)

    ISABEL M. MÜLLER

    2003-05-01

    Full Text Available Sponges (Porifera represent the lowest metazoan phylum, characterized by a pronounced plasticity in the determination of cell lineages, and they are the closest related taxon to the hypothetical ancestral animal, the Urmetazoa, from which the metazoan lineages diverged. In a first approach to elucidate the molecular mechanisms controlling the switch from the cell lineage with a putative indefinite growth capacity to senescent, somatic cells, the activity of the telomerase as an indicator for immortality has been determined. The studies were performed with the marine demosponges Suberites domuncula and Geodia cydonium, in vivo with tissue but also in vitro using the primmorph system. Primmorphs are formed from dissociated cells which have retained their proliferation potency. It was found that the activity of telomerase in tissue of both sponges is high. Based on this and additional findings it is assumed that the separation of the senescent sponge cell lineage from the immortal germ-/somatic cell lineage is triggered by the loss of contact to cell adhesion factors. First evidence is included which suggests that the final progress of the senescent, telomerase-negative cells to cell death is caused by apoptosis.

  10. 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.

  11. Study of the expressions of p53 and bcl-2 genes, the telomerase activity and apoptosis in GIST patients

    Institute of Scientific and Technical Information of China (English)

    Qiang Wang; You-Wei Kou

    2007-01-01

    AIM: To explore the relationship between clinicobiological behavior and the expression levels of telomerase activity,apoptosis, p53 gene and bcl-2 gene in gastrointestinal stromal tumors (GISTs).METHODS: The intensity of telomerase activity,apoptosis, p53 and bcl-2 expression in GISTs were detected by telomeric repeat amplification protocol, in situ end-labeling technique, and immunohistochemistry,respectively.RESULTS: The positive rates of telomerase activity of malignant GIST, potential malignant GIST and benign GIST were 85% (17/20), 22.8% (2/9) and 0 (0/9),respectively. The apoptosis indices of malignant GIST,potential malignant GIST, and benign GIST were 11.7 ± 5.4, 30.2 ± 5.6 and 45.2 ± 7.2, respectively. The intensity of telomerase activity and apoptosis were related to the biological characteristics of GISTs (85% vs 22.8%, 0, 0; P < 0.01 or 11.7±5.4 vs 30.2 ± 5.6, 45.2 ± 7.2, 72.1 ± 9.3; P < 0.05). The intensity of telomerase activity was negatively correlated with cellular apoptosis (22.9 ± 8.4 vs 9.5 ± 5.7, P < 0.01). The intensity of telomerase activity was positively correlated with p53,bcl-2 expression (40.0% vs 78.9%, 40.0% vs 84.2%;P < 0.05).CONCLUSION: The detection of telomerase activity,apoptosis and its control genes in GIST will be helpful for the discrimination of the malignant and benign GIST and evaluation of the prognosis.

  12. 48. The value of CT scan and detection of telomerase activity in biopsy specimens for early diagnosis of lung carcinoma

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Objective: To evaluate the diagnostic value of telomerase activity in the specimens of biopsy with bronchoscopy or cutting needle. Methods: Telomerase activity was measured in the biopsy apecimens taken from 52 patients suspected of having early lung cancer by CT scan. The PCR based silver staining telomeric repeat amplification protocol (TRAP) was used for detection of telomerase activity in 22 patients with early lung cancer (T1N0M0). Control study was made on the specimens taken from 24 patients with benign disease (cyst 3, TB 6, pseudtumor 5, pneumonjia 10). Results: The positive rates of telomerase activity were 86.45% (19/22) and 4.2% (1/24) in early lung cancers and benign lesions respectively (P<0.01). It was significantly higher in early lung cancers than in benign disease. All cases were diagnosed with surgical pathology and following for 2 years. Conclusion: Detecting telomerase activity in preoperative bronchoscope and cutting needle biopsy specimens may contribute to diagnosis of early lung cancer.

  13. Telomere Length in Peripheral Blood Mononuclear Cells of Patients on Chronic Hemodialysis Is Related With Telomerase Activity and Treatment Duration.

    Science.gov (United States)

    Stefanidis, Ioannis; Voliotis, Georgios; Papanikolaou, Vassilios; Chronopoulou, Ioanna; Eleftheriadis, Theodoros; Kowald, Axel; Zintzaras, Elias; Tsezou, Aspasia

    2015-09-01

    Telomere shortening to a critical limit is associated with replicative senescence. This process is prevented by the enzyme telomerase. Oxidative stress and chronic inflammation are factors accelerating telomere loss. Chronic hemodialysis, typically accompanied by oxidative stress and inflammation, may be also associated with replicative senescence. To test this hypothesis, we determined telomere length and telomerase activity in peripheral blood mononuclear cells (PBMCs) in a cross-sectional study. Hemodialysis patients at the University Hospital Larissa and healthy controls were studied. Telomere length was determined by the TeloTAGGG Telomere Length Assay and telomerase activity by Telomerase PCR-ELISA (Roche Diagnostics GmbH, Mannheim, Germany). We enrolled 43 hemodialysis patients (17 females; age 65.0 ± 12.7 years) and 23 controls (six females; age 62.1 ± 15.7 years). Between the two groups, there was no difference in telomere length (6.95 ± 3.25 vs. 7.31 ± 1.96 kb; P = 0.244) or in telomerase activity (1.82 ± 2.91 vs. 2.71 ± 3.0; P = 0.085). Telomere length correlated inversely with vintage of hemodialysis (r = -0.332, P = 0.030). In hemodialysis patients, positive telomerase activity correlated with telomere length (r = 0.443, P = 0.030). Only age, and neither telomere length nor telomerase activity, was an independent survival predictor (hazard ratio 1.116, 95% confidence interval 1.009-1.234, P = 0.033). In this study, telomere length and telomerase activity in PBMCs are not altered in hemodialysis patients compared with healthy controls. Long duration of hemodialysis treatment is associated with telomere shortening and positive telomerase activity with an increased telomere length in PBMCs of hemodialysis patients. The underlying mechanism and clinical implications of our findings require further investigation.

  14. Acycloguanosyl 5'-thymidyltriphosphate, a thymidine analogue prodrug activated by telomerase, reduces pancreatic tumor growth in mice.

    Science.gov (United States)

    Polvani, Simone; Calamante, Massimo; Foresta, Valeria; Ceni, Elisabetta; Mordini, Alessandro; Quattrone, Alessandro; D'Amico, Massimo; Luchinat, Claudio; Bertini, Ivano; Galli, Andrea

    2011-02-01

    Gemcitabine is the standard of care for metastatic and nonresectable pancreatic tumors. Phase II and III trials have not demonstrated efficacy of recently developed reagents, compared with gemcitabine alone; new chemotherapic agents are needed. Ninety percent of pancreatic tumors have telomerase activity, and expression correlates with tumor stage. We developed a thymidine analogue prodrug, acycloguanosyl 5'-thymidyltriphosphate (ACV-TP-T), that is metabolized by telomerase and releases the active form of acyclovir. We investigated the antitumor efficacy of ACV-TP-T in vitro and in vivo. We evaluated proliferation and apoptosis of human pancreatic cancer cells (PANC-1, MiaPaca2, BxPc3, PL45, and Su.86.86) incubated with ACV-TP-T. The presence of ACV-TP-T and its metabolite inside the cells were analyzed by mass spectrometry. In vivo efficacy was evaluated in nude mice carrying PANC-1 or MiaPaca2 pancreatic xenograft tumors. The prodrug of ACV-TP-T was actively metabolized inside pancreatic cancer cells into the activated form of acyclovir; proliferation was reduced, apoptosis was increased, and the cell cycle was altered in pancreatic cancer incubated with ACV-TP-T, compared with controls. Administration of ACV-TP-T to mice reduced growth, increased apoptosis, and reduced proliferation and vascularization of pancreatic xenograft tumors. ACV-TP-T, a thymidine analogue that is metabolized by telomerase and releases the active form of acyclovir, reduces proliferation and induces apoptosis of human pancreatic cancer cell lines in vitro and pancreatic xenograft tumors in mice. Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.

  15. Anti-tumor effect of 5-aza-2'-deoxycytidine by inhibiting telomerase activity in hepatocellular carcinoma cells

    Institute of Scientific and Technical Information of China (English)

    Shuang-Fen Tao; Chang-Song Zhang; Xian-Ling Guo; Yun Xu; Shan-Shan Zhang; Jian-Rui Song; Rong Li

    2012-01-01

    AIM:To investigate the effect of the demethylating reagent 5-aza-2'-deoxycitidine (DAC) on telomerase activity in hepatocellular carcinoma (HCC) cell lines,SMMC-7721 and HepG2.METHODS:The related gene expression in cell lines was examined by real-time reverse transcription-polymerase chain reaction and Western blotting analysis.The telomerase activity was examined by telomeric repeat amplification protocol-enzyme-linked immunosorbent assay and DNA methylation was determined by methylation-specific polymerase chain reaction.RESULTS:The telomerase activity was significantly reduced in both cell lines treated with DAC,accompanied by downregulation of telomerase reverse transcriptase (hTERT).We also observed the effect of DAC on the methylation status of hTERT promoter and the expression of regulatory genes,such as c-myc,p15,p16,p21,E2F1,and WT1.The methylation status of hTERT promoter could be reversed in SMMC-7721 by DAC,but not in HepG2 cells.However,p16 expression could be reactivated by demethylation of its promoter,and c-Myc expression was repressed in both cell lines.Moreover,DAC could enhance the sensitivity to the chemotherapeutic agents,such as cisplatin,by induction of apoptosis of HCC cells.CONCLUSION:The DAC exerts its anti-tumor effects in HCC cells by inhibiting the telomerase activity.

  16. Telomerase activation in posterior fossa group A ependymomas is associated with dismal prognosis and chromosome 1q gain.

    Science.gov (United States)

    Gojo, Johannes; Lötsch, Daniela; Spiegl-Kreinecker, Sabine; Pajtler, Kristian W; Neumayer, Katharina; Korbel, Pia; Araki, Asuka; Brandstetter, Anita; Mohr, Thomas; Hovestadt, Volker; Chavez, Lukas; Kirchhofer, Dominik; Ricken, Gerda; Stefanits, Harald; Korshunov, Andrey; Pfister, Stefan M; Dieckmann, Karin; Azizi, Amedeo A; Czech, Thomas; Filipits, Martin; Kool, Marcel; Peyrl, Andreas; Slavc, Irene; Berger, Walter; Haberler, Christine

    2017-09-01

    Ependymomas account for up to 10% of childhood CNS tumors and have a high rate of tumor recurrence despite gross total resection. Recently, classification into molecular ependymoma subgroups has been established, but the mechanisms underlying the aggressiveness of certain subtypes remain widely enigmatic. The aim of this study was to dissect the clinical and biological role of telomerase reactivation, a frequent mechanism of cancer cells to evade cellular senescence, in pediatric ependymoma. We determined telomerase enzymatic activity, hTERT mRNA expression, promoter methylation, and the rs2853669 single nucleotide polymorphism located in the hTERT promoter in a well-characterized cohort of pediatric intracranial ependymomas. In posterior fossa ependymoma group A (PF-EPN-A) tumors, telomerase activity varied and was significantly associated with dismal overall survival, whereas telomerase reactivation was present in all supratentorial RelA fusion-positive (ST-EPN-RELA) ependymomas. In silico analysis of methylation patterns showed that only these two subgroups harbor hypermethylated hTERT promoters suggesting telomerase reactivation via epigenetic mechanisms. Furthermore, chromosome 1q gain, a well-known negative prognostic factor, was strongly associated with telomerase reactivation in PF-EPN-A. Additional in silico analyses of gene expression data confirmed this finding and further showed enrichment of the E-twenty-six factor, Myc, and E2F target genes in 1q gained ependymomas. Additionally, 1q gained tumors showed elevated expression of ETV3, an E-twenty-six factor gene located on chromosome 1q. Taken together we describe a subgroup-specific impact of telomerase reactivation on disease progression in pediatric ependymoma and provide preliminary evidence for the involved molecular mechanisms.

  17. 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

  18. Evaluation of Manisa propolis effect on leukemia cell line by telomerase activity.

    Science.gov (United States)

    Gunduz, Cumhur; Biray, Cigir; Kosova, Buket; Yilmaz, Berna; Eroglu, Zuhal; Sahin, Fahri; Omay, Serdar Bedii; Cogulu, Ozgur

    2005-11-01

    Propolis is a resinous substance which is used by bees to repair and maintain their hives. It has more than 180 compounds including flavonoids, phenolic acids and its esters which have anti-inflammatory, antibacterial, antiviral, immunomodulatory, antioxidant and antiproliferative effects. Propolis is shown to inhibit cell division and protein synthesis. However the exact mechanism underlying antitumor effect is not clearly described. On the other hand progressive telomere shortening to a critical level results with senescence of normal cells by inducing apoptosis and telomerase prevents erosion of telomeres. In this study we aimed to evaluate hTERT ratios in propolis-treated T-cell acute lymphoblastic leukemia (CCFR-CEM) cell line. Cell counts and cell viability of propolis-treated and propolis-free T-cell acute lymphoblastic leukemia (CCFR-CEM) cell line were assessed by trypan blue dye exclusion test and MTT assay. The LightCycler instrument was used (online real-time PCR) for the quantification of hTERT in CCFR-CEM cell line. The hTERT ratio significantly decreased 60 and 93% after 24 and 72 h respectively compared to the initial value of the cells incubated with propolis. It had almost no cytotoxic effect and caused 30, 30, 22 and 12% decrease in cell counts after 24, 48, 72 and 96 h respectively which is statistically significant. In conclusion propolis may show antitumor and apoptotic effect via inhibiting telomerase expression besides the mechanisms which have been described previously.

  19. Investigation of telomerase activity and apoptosis on invasive ductal carcinoma of the breast using immunohistochemical and Western blot methods.

    Science.gov (United States)

    Simsek, B C; Turk, B A; Ozen, F; Tuzcu, M; Kanter, M

    2015-08-01

    Invasive ductal carcinoma (IDC) comprises the largest group of breast cancers. This study aimed to investigate telomerase activity and apoptosis using immunohistochemical and Western blot methods. In total, 75 cases that had been diagnosed as IDC and 20 cases that had undergone a freezing procedure were included. The histological sections were stained with Bax, Bcl-2, hTERT and BNIP3. The ages of the patients, as well as their hormonal status and tumour sizes and grades were evaluated, as well as the staining characteristics of the antibodies in question. A decrease in Bcl-2 positivity and an increase in Bax positivity were found immunohistochemically with increasing tumour grades. The data obtained by western blot method showed that Bcl-2 was highest in grade 1 tumours although these results were not statistically significant. The relationship between estrogen and progesterone receptor positivity and Bcl-2 was statistically significant, suggesting there is hormonal control through apoptosis. BNIP3 was found to be decreased with increasing tumour grades. Similarly, BNIP3 was found to be having the lowest value in grade 3 tumours by western blot method. Furthermore, hTERT was found to be increased with increasing tumour grades. In the western blot method, hTERT increased nearly four-fold compared to the control. In addition, hTERT, which was seen in very high levels in tumours, may be a helpful cancer marker. Both hTERT and BNIP3 are important markers that can provide information about prognosis. Big improvements can be achieved in tumour progression control with new treatment modalities that stop telomerase activity and hypoxic cell death.

  20. A novel DNA tetrahedron-hairpin probe for in situ"off-on" fluorescence imaging of intracellular telomerase activity.

    Science.gov (United States)

    Feng, Qiu-Mei; Zhu, Meng-Jiao; Zhang, Ting-Ting; Xu, Jing-Juan; Chen, Hong-Yuan

    2016-04-21

    A novel three-dimensionally structured DNA probe is reported to realize in situ"off-on" imaging of intracellular telomerase activity. The probe consists of a DNA tetrahedron and a hairpin DNA on one of the vertices of the DNA tetrahedron. It is composed of four modified DNA segments: S1-Au nanoparticle (NP) inserting a telomerase strand primer (TSP) and S2-S4, three Cy5 dye modified DNA segments. Fluorescence of Cy5 at three vertices of the DNA tetrahedron is quenched by the Au NP at the other vertex due to the effective fluorescence resonance energy transfer (FRET) ("off" state). When the probe meets telomerase, the hairpin structure changes to rod-like through complementary hybridization with the telomerase-triggered stem elongation product, resulting in a large distance between the Au NP and Cy5 and the recovery of Cy5 fluorescence ("on" state). The molar ratio of 3 : 1 between the reporter (Cy5) and the target related TSP makes the probe show high sensitivity and recovery efficiency of Cy5 in the presence of telomerase extracted from HeLa cells. Given the functional and compact nanostructure, the mechanically stable and noncytotoxic nature of the DNA tetrahedron, this FRET-based probe provides more opportunities for biosensing, molecular imaging and drug delivery.

  1. Label-free ultrasensitive detection of telomerase activity via multiple telomeric hemin/G-quadruplex triggered polyaniline deposition and a DNA tetrahedron-structure regulated signal.

    Science.gov (United States)

    Liu, Yuanjian; Wei, Min; Liu, Xu; Wei, Wei; Zhao, Hongyu; Zhang, Yuanjian; Liu, Songqin

    2016-01-31

    Label-free detection of telomerase activity was done by using telomeric hemin/G-quadruplex triggered polyaniline deposition, not only on themselves but also on the DNA tetrahedron-structure (DTS). DTS size has a great impact on telomerase accessibility, reactivity and detection sensitivity. The method has been used to evaluate bladder cancer development.

  2. Epidermal growth factor activates telomerase activity by direct binding of Ets-2 to hTERT promoter in lung cancer cells.

    Science.gov (United States)

    Hsu, Chung-Ping; Lee, Li-Wen; Tang, Sheau-Chung; Hsin, I-Lun; Lin, Yu-Wen; Ko, Jiunn-Liang

    2015-07-01

    Growth signals are directly or indirectly involved in telomerase regulation. In this study, we investigated molecular mechanisms of the effect of EGF (epidermal growth factor) on regulating hTERT (human telomerase reverse transcriptase) expression. To elucidate specific transcription factors involved in EGF-stimulated hTERT transcription in A549 and H1299 lung cancer cells, transcription factors drives hTERT promoter activity, such as Myc, Mad, and Ets-2, was evaluated on luciferase reporter assay. The upregulation of hTERT promoter by Ets-2 and Myc were abolished by Mad. Using DAPA (DNA affinity precipitation assay), Ets-2 binding to SNP (T) was stronger than Ets-2 binding to SNP (C) at -245 bp upstream of the transcription start site within the core promoter of hTERT. Ets-2 silence by siRNA decreased hTERT expression at mRNA and protein levels. The regulation of hTERT promoter by EGF/Ets-2 was diminished via the EGFR kinase signal pathway-specific inhibitors AG1478 and Iressa. Inhibitors of Erk and Akt inhibited Ets-2-activated hTERT promoter activity. These data suggested that Ets-2, a genuine cancer-specific transcription factor, is actively involved in EGFR kinase-induced hTERT overexpression pathway in lung cancer cells. Blockage of this pathway may contribute to targeted gene therapy in lung cancer.

  3. Analysis of the age of Panax ginseng based on telomere length and telomerase activity.

    Science.gov (United States)

    Liang, Jiabei; Jiang, Chao; Peng, Huasheng; Shi, Qinghua; Guo, Xiang; Yuan, Yuan; Huang, Luqi

    2015-01-23

    Ginseng, which is the root of Panax ginseng (Araliaceae), has been used in Oriental medicine as a stimulant and dietary supplement for more than 7,000 years. Older ginseng plants are substantially more medically potent, but ginseng age can be simulated using unscrupulous cultivation practices. Telomeres progressively shorten with each cell division until they reach a critical length, at which point cells enter replicative senescence. However, in some cells, telomerase maintains telomere length. In this study, to determine whether telomere length reflects ginseng age and which tissue is best for such an analysis, we examined telomerase activity in the main roots, leaves, stems, secondary roots and seeds of ginseng plants of known age. Telomere length in the main root (approximately 1 cm below the rhizome) was found to be the best indicator of age. Telomeric terminal restriction fragment (TRF) lengths, which are indicators of telomere length, were determined for the main roots of plants of different ages through Southern hybridization analysis. Telomere length was shown to be positively correlated with plant age, and a simple mathematical model was formulated to describe the relationship between telomere length and age for P. ginseng.

  4. Relationship between the telomerase activity and the growth kinetics of the human umbilical cord derived mesenchymal stem cells

    Directory of Open Access Journals (Sweden)

    Leila Hosseinzadeh Anvar

    2016-08-01

    Full Text Available Background: Telomerase as an enzyme with reverse transcriptase activity has an essential role in telomere maintenance by adding a telomere repeat sequence to the 3' end of chromosome and is important for regulating of many processes in embryonic development including cell proliferation and differentiation. Human umbilical cord-derived mesenchymal stem cells (hUC-MSCs with a self-renewal capacity are cells that can differentiate into various germ layer derivatives including neural cells and cardiomyocytes, and undergo biological changes during long-term cultivation. Hence, the passage number in which the cells expanded seems to be very important for proliferating and differentiating. This study was aimed at investigating the relationship between the telomerase activity and the growth rate of (hUC-MSCs at different passages. Methods: This experimental study was performed in Ardabil University of Medical Sciences, Iran, from March 2014 to December 2014. The umbilical cord samples were obtained from full-term neonate hospitalized in Alavi’s Hospital in Ardabil under sterile conditions. The umbilical vessels were clear off and the small pieces of the umbilical cord were cultured in Dulbecco's modified eagle's medium (DMEM supplemented with 20% fetal bovine serum (FBS. Then, the hUC-MSCs were harvested from passage one to three to calculate the population doubling time (PDT and extract proteins by using CHAPS lysis buffer. Finally, the telomerase activity of the cells at different passages was measured by telomeric repeat amplification protocol (TRAP and qRT-TRAP assays. Results: The hUC-MSCs population doubling time at passage from 1 to 3 were calculated as the average of 54.68±1.92, 55.03±1.71 and 69.41±2.54 hours, respectively, suggesting the higher cell passage number, the more extended PDT. The threshold cycles (CTs for the telomerase activity also showed 30.58±0.51, 27.24±0.74 and 32.13±0.75 for the cell passage from one to three

  5. Anti-aging effect of estrogen on telomerase activity in ovariectomised rats--animal model for menopause.

    Science.gov (United States)

    Cen, Jiaping; Zhang, Hongyan; Liu, Yuanwei; Deng, Miao; Tang, Shanshan; Liu, Wenhua; Zhang, Zhifen

    2015-07-01

    The aim of this study was to investigate the anti-aging effects of exogenous estrogen on telomerase activity in ovariectomized female Sprague-Dawley rats. Thirty-three 12-week-old female rats were divided into three groups: the ovariectomized-Treated group (Treated, n = 11), the ovariectomized control group (OVX, n = 11) and the Sham-operated group (Sham, n = 11). The rats in the Treated group were given 0.21 mg/kg estradiol valerate intragastric administration while other two groups were given the amount of physiological saline daily. All of the animals were euthanized 12 weeks after treatment, and abdominal aortic blood samples were taken to assess the level of estradiol (E2), follicle stimulating hormone (FSH). Telomerase activity and telomerase reverse transcriptase (TERT) mRNA expression in the heart, liver, brain tissues of all rats were measured by reverse transcriptional polymerase chain reaction (RT-PCR) and competitive enzyme-linked immunosorbent assay (ELISA). Compared to the OVX and Sham group, telomerase activity and TERT mRNA levels were significantly increased in the heart, liver and brain tissues of rats in the Treated group (p anti-aging.

  6. Telomerase activity in the regenerative basal layer of the epidermis inhuman skin and in immortal and carcinoma-derived skin keratinocytes.

    Science.gov (United States)

    Härle-Bachor, C; Boukamp, P

    1996-06-25

    Cellular senescence is defined by the limited proliferative capacity of normal cultured cells. Immortal cells overcome this regulation and proliferate indefinitively. One step in the immortalization process may be reactivation of telomerase activity, a ribonucleoprotein complex, which, by de novo synthesized telomeric TTAGGG repeats, can prevent shortening of the telomeres. Here we show that immortal human skin keratinocytes, irrespective of whether they were immortalized by simian virus 40, human papillomavirus 16, or spontaneously, as well as cell lines established from human skin squamous cell carcinomas exhibit telomerase activity. Unexpectedly, four of nine samples of intact human skin also were telomerase positive. By dissecting the skin we could show that the dermis and cultured dermal fibroblasts were telomerase negative. The epidermis and cultured skin keratinocytes, however, reproducibly exhibited enzyme activity. By separating different cell layers of the epidermis this telomerase activity could be assigned to the proliferative basal cells. Thus, in addition to hematopoietic cells, the epidermis, another example of a permanently regenerating human tissue, provides a further exception of the hypothesis that all normal human somatic tissues are telomerase deficient. Instead, these data suggest that in addition to contributing to the permanent proliferation capacity of immortal and tumor-derived keratinocytes, telomerase activity may also play a similar role in the lifetime regenerative capacity of normal epidermis in vivo.

  7. 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.

  8. Topological effects of charge transfer in telomere G-quadruplex: Mechanism on telomerase activation and inhibition

    CERN Document Server

    Wang, Xin

    2015-01-01

    We explore charge transfer in the telomere G-Quadruplex (TG4) DNA theoretically by the nonequilibrium Green's function method, and reveal the topological effect of charge transport in TG4 DNA. The consecutive TG4(CTG4) is semiconducting with 0.2 ~ 0.3eV energy gap. Charges transfers favorably in the consecutive TG4, but are trapped in the non-consecutive TG4 (NCTG4). The global conductance is inversely proportional to the local conductance for NCTG4. The topological structure transition from NCTG4 to CTG4 induces abruptly ~ 3nA charge current, which provide a microscopic clue to understand the telomerase activated or inhibited by TG4. Our findings reveal the fundamental property of charge transfer in TG4 and its relationship with the topological structure of TG4.

  9. Topological Effects of Charge Transfer in Telomere G-Quadruplex Mechanism on Telomerase Activation and Inhibition

    Science.gov (United States)

    Wang, Xin; Liang, Shi-Dong

    2013-02-01

    We explore the charge transfer in the telomere G-Quadruplex (TG4) DNA theoretically by the nonequilibrium Green's function method, and reveal the topological effect of the charge transport in TG4 DNA. The consecutive TG4 (CTG4) is semiconducting with 0.2 0.3 eV energy gap. Charges transfer favorably in the CTG4, but are trapped in the nonconsecutive TG4 (NCTG4). The global conductance is inversely proportional to the local conductance for NCTG4. The topological structure transition from NCTG4 to CTG4 induces abruptly 3nA charge current, which provide a microscopic clue to understand the telomerase activated or inhibited by TG4. Our findings reveal the fundamental property of charge transfer in TG4 and its relationship with the topological structure of TG4.

  10. 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.

  11. Telomeres, telomerase and premature ovarian failure

    Directory of Open Access Journals (Sweden)

    Renata Košir Pogačnik

    2011-11-01

    Full Text Available Telomeres are specialized structures at the ends of chromosomes, consisting of six repeated nucleotides in TTAGGG sequence. Genome stability is partly maintained by the architecture of telomeres and is gradually lost as telomeres progressively shorten with each cell replication. Critically shortened telomeres are recognized by DNA repair mechanisms as DNA damage and the cell replication cycle stops. The cell eventually dies or undergoes cell apoptosis. Telomere represents a cellular marker of biological age and are therefore also called cell mitotic clock. The enzyme that counteracts telomere shortening by adding nucleotides to the 3’ end of DNA strand is called telomerase. It is composed of the RNA subunit (TR, which is special type of messenger RNA (mRNA, the catalytic protein subunit (TERT, which works as a reverse transcriptase and numerous additional proteins. Telomerase is active in some germline, epithelial and haemopoietic cells, but in most somatic cells the activity is undetectable. In literature, the length of telomeres is closely connected with premature ovarian failure (POF. POF is generally defined as the onset of menopause before the age of 40. The causes of disease are genetical, autoimmune, iatrogenic or if we cannot establish the cause – idiopathic. A lot of studies examined correlation between idiopathic POF, length of telomeres and telomerase activity. The studies mostly show that women with POF have shortened telomeres and decreased activity of telomerase as compared to healthy women.

  12. 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...

  13. 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.

  14. 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

  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...... compared with PBMC from normal donors. This increase was most pronounced in the subpopulation of CD4(+) T cells, which were significantly above the activity of the CD8(+) T cells in atopic dermatitis, psoriasis patients, and control persons. The telomere length was significantly reduced in all T cell...... subsets from both atopic dermatitis and psoriasis patients compared with normal individuals. Furthermore, the telomere length was found to be significantly shorter in CD4(+) memory T cells compared with the CD4(+) naive T cells, and both of the cell subsets from diseases were shown to be of significantly...

  16. 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

  17. Antitumor polycyclic acridines. 8.(1) Synthesis and telomerase-inhibitory activity of methylated pentacyclic acridinium salts.

    Science.gov (United States)

    Heald, Robert A; Modi, Chetna; Cookson, Jenny C; Hutchinson, Ian; Laughton, Charles A; Gowan, Sharon M; Kelland, Lloyd R; Stevens, Malcolm F G

    2002-01-31

    Two short routes to novel methylated pentacyclic quinoacridinium salts have been devised. New compounds display telomerase-inhibitory potency (quino[4,3,2-kl]acridinium methosulfate (12d, RHPS4, NSC 714187) has a higher selectivity for triplex and quadruplex DNA structures than the 3,6,8,11,13-pentamethyl analogue (12c, RHPS3, NSC 714186) and a low overall growth-inhibitory activity in the NCI 60 cell panel (mean GI(50) 13.18 microM); in addition, the activity profile of 12d does not COMPARE with agents of the topoisomerase II class. Compound 12d is soluble in water, stable in the pH range of 5-9, efficiently transported into tumor cells, and is currently the lead structure for further elaboration in this new class of telomerase inhibitor.

  18. Effects of Ganoderma lucidum (Higher Basidiomycetes) Extracts on the miRNA Profile and Telomerase Activity of the MCF-7 Breast Cancer Cell Line.

    Science.gov (United States)

    Gonul, Oyku; Aydin, Hikmet Hakan; Kalmis, Erbil; Kayalar, Husniye; Ozkaya, Ali Burak; Atay, Sevcan; Ak, Handan

    2015-01-01

    Ganoderma lucidum is a medicinal higher Basidiomycetes mushroom that exerts anticancer effects through several different mechanisms. This study investigated the effects of G. lucidum on the telomerase activity and microRNA (miRNA) profiles of MCF-7 cells. According to the cytotoxicity results, the G. lucidum ether extract exhibits the highest cytotoxic potency; therefore it was chosen for the subsequent telomerase activity assay and miRNA profiling. The telomerase activity observed in the cells treated with a half-maximal inhibitory concentration of G. lucidum ether extract (100 µg/mL in dimethyl sulfoxide) was 32.2% lower than that of the control cells treated with 1% dimethyl sulfoxide. Among 1066 miRNAs, the most downregulated miRNA was hsa-miR-27a* (4.469-fold), and the most upregulated miRNA was hsa-miR-1285 (10.462-fold). A database search revealed the predicted miRNAs that target the catalytic subunit of the telomerase enzyme telomerase reverse transcriptase, and only miR-3687 (upregulated 2.153-fold) and miR-1207-5p (upregulated 2.895-fold) were changed by at least 2-fold. The miRNA profile changes demonstrated in this study provide a data set regarding their effects on the pathways that regulate telomerase activity in MCF-7 breast cancer cells treated with G. lucidum. These data should aid the development of novel cancer treatment strategies.

  19. P04.24MUTATIONS OF THE TERT PROMOTER CORRELATE WITH ENHANCED TELOMERASE ACTIVATION AND PREDICT A WORSE PROGNOSIS IN PRIMARY GLIOBLASTOMA PATIENTS

    OpenAIRE

    Spiegl-Kreinecker, S.; Loetsch, D.; Laaber, M.; Pichler, J; Weis, S.; Ghanim, B; Webersinke, G; Olschowski, A; Berger, W

    2014-01-01

    The stabilization of telomeres by upregulation of telomerase is compulsive for indefinite proliferation and cell immortalization therefore representing a main feature of malignant solid tumors, including gliomas. However, the mechanisms responsible for cancer-associated telomerase activation are not completely understood. Recently, defined mutations in the TERT promoter were identified in a variety of tumors, most frequent in primary glioblastomas (GBM). Presence of the mutations was associat...

  20. Telomerase activity (TMA) in tumour and peritumoural tissues in a rat liver cancer model.

    Science.gov (United States)

    Zhang, Huo-Jun; Yang, Ji-Jin; Tian, Jian-Ming; Wang, Pei-Jun; Shao, Cheng-Wei; Zuo, Chang-Jing; Zhang, Shun-Min; Gupta, Sanjay

    2009-02-01

    To study the levels of telomerase activity (TMA) in tumour and peritumoural tissues in a liver cancer model in rats, and to study the change in TMA expression over time. Using the telomeric repeated amplification protocol (TRAP), TMA was measured in tumour tissue, peritumoural tissue and normal liver tissue of Walker-256 tumour-bearing rats at 4, 6 and 8 days after tumour implantation. TMA at day 4, 6 and 8 was 0.767+/-0.117, 0.768+/-0.118 and 0.774+/-0.111 in tumour tissue, 0.389+/-0.263, 0.492+/-0.253 and 0.584+/-0.239 in peritumoural tissue, and 0.231+/-0.022, 0.229+/-0.022 and 0.233+/-0.021 in normal liver tissue, respectively. TMA in tumour tissue was higher than that in peri-tumour and normal liver tissues at all time points of measurement (P TMA levels in tumour tissue and normal liver tissue did not show any change over time. TMA level in the peritumoural tissue increased with time; TMA level in animals sacrificed at day 8 was higher than that seen in animals sacrificed at day 4 (P TMA in walker-256 tumour-bearing rats was higher than that in normal and peritumoural tissues. TMA level in the peritumoural tissue increased with time suggesting that TMA activation in peritumoural tissue may be an important factor promoting tumour growth.

  1. 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

  2. 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.

  3. 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.

  4. ES micro-environment enhances stemness and inhibits apoptosis in human limbal stem cells via the maintenance of telomerase activity.

    Directory of Open Access Journals (Sweden)

    Zhiping Liu

    Full Text Available Our previous work had found that telomerase rejuvenated in the cytoplasm of corneal epithelial cells cultured in embryonic stem cell-conditioned medium, the functional properties of stem-like corneal epithelial cells can be enhanced by co-culturing with embryonic stem cells (ESCs via activation of the integrinβ1-FAK-PI3K/Akt signaling pathway. The goal of this study was to explore the potential molecular mechanisms of the ES micro-environment that enhance the stem cell-like phenotype and inhibit apoptosis in human limbal stem cells (LSC. The LSC were cultured in different media, either CnT-20 medium or CnT-20 +20% ES culture supernatant (ESC-CM. We observed that LSC cultured in ESC-CM had an increased proliferative capacity, greater serial passage capacity, higher colony-forming efficiency (CFE and higher levels of stem cell-associated marker than those cultured in CnT-20. Compared with CnT-20, ESC-CM enhanced the undifferentiated status and inhibited apoptosis in the LSC by promoting the maintenance of telomerase activity, which could reduce the generation of reactive oxygen species (ROS, maintain the membrane potential (Δψm at higher levels and reduce the expression of the p21 protein. Our findings indicated that ESC-CM system induced LSC to maintain a stem cell phenotype and inhibit the process of apoptosis. These effects might partially be achieved via the telomerase-p21-mitochondrial axis and the activation of the FAK/Wnt signaling pathways. This study may have high impact and clinic implication on the expansion of LSC in regenerative medicine, especially for ocular surface reconstruction.

  5. 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.

  6. Evaluation of Effects of Quercetin (3, 3’, 4’, 5, 7-pentohidroxyflavon on Apoptosis and Telomerase Enzyme Activity in MCF-7 and NIH-3T3 Cell Lines Compared with Tamoxifen

    Directory of Open Access Journals (Sweden)

    Ayşe Ak

    2011-09-01

    Full Text Available Objective: Quercetin has been shown to inhibit the proliferation of cancer cells. Tamoxifen is used for breast cancer. In this study, we have aimed to investigate the effects of quercetin and tamoxifen on telomerase enzyme activity and apoptosis in two cell lines.Methods: In this study, 10, 50 and 100 µM of quercetin and tamoxifen were used to treat MCF-7 and NIH-3T3. Apoptosis was determined by the TUNEL method (Terminal Deoxynucleotide Transferase dUTP Nick End Label and telomerase enzyme activity was determined by ELISA (Enzyme-Linked Immunosorbent Assay. Results: In the NIH3T3 cell line, only 100 µM quercetin and tamoxifen induced significant apoptosis. In the MCF-7 cell line 10 µM and 100 µM quercetin in the 24th hour and 100 µM quercetin in the 72nd hour induce apoptosis. In 24th and 48th hours, 50 µM tamoxifen and 100 µM tamoxifen in the 24th and 48th hours induce apoptosis in the MCF-7 cell line. In MCF-7 and NIH-3T3 cell lines, all doses of quercetin and tamoxifen reduced telomerase enzyme activity compared to the control group. Conclusion: In this study, it was shown that quercetin has similar effects to tamoxifen. However quercetin induces apoptosis more than decreasing telomerase enzyme activities, being different from tamoxifen. We hope that the findings will assist in developing new therapeutic pathways for preventing breast cancer. However, there should be many more studies in order to discover quercetin and other potential drugs.

  7. Telomerase and the endocrine system.

    Science.gov (United States)

    Pacini, Furio; Cantara, Silvia; Capezzone, Marco; Marchisotta, Stefania

    2011-03-29

    Telomeres are nucleoprotein complexes located at the ends of chromosomes that have a critical role in the maintenance of chromosomal integrity. This involvement is based on complex secondary and tertiary structures that rely on DNA-DNA, DNA-protein and protein-protein interactions. De novo synthesis and maintenance of telomere repeats is controlled by telomerase, a specialized complex that consists of a telomerase RNA component and a protein component--telomerase reverse transcriptase. When telomerase is silent (its default state in differentiated somatic cells), chromosomes shorten with every cell division, thus limiting the lifespan of the cells (the process of senescence) and preventing unlimited cell proliferation, which might eventually lead to the development of cancer. During this process, occasionally, a cell can activate telomerase, which stabilizes short telomeres and enables immortalization-a process essential for malignant transformation. Thus, although telomere erosion is a barrier to malignant progression, paradoxically, in certain circumstances it might also trigger tumorigenesis. A number of studies have demonstrated unequivocally that reactivation of telomerase in the presence of short telomeres is one of the most common features of human cancers, including those of the endocrine system.

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

    Science.gov (United States)

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

    2009-01-30

    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, the telomerase RNA (TERC), and dyskerin. Here, we identify a holoenzyme subunit, TCAB1 (telomerase Cajal body protein 1), that is notably enriched in Cajal bodies, nuclear sites of RNP processing that are important for telomerase function. TCAB1 associates with active telomerase enzyme, established telomerase components, and small Cajal body RNAs that are involved in modifying splicing RNAs. Depletion of TCAB1 by using RNA interference prevents TERC from associating with Cajal bodies, disrupts telomerase-telomere association, and abrogates telomere synthesis by telomerase. Thus, TCAB1 controls telomerase trafficking and is required for telomere synthesis in human cancer cells.

  9. Telomerase activity and telomere length in the colorectal polyp-carcinoma sequence Actividad de la telomerasa y longitud del telómero en la secuencia pólipo-carcinoma colorrectal

    Directory of Open Access Journals (Sweden)

    C. Valls Bautista

    2009-03-01

    Full Text Available Objective: the role of telomerase activity and telomere length in the adenoma-carcinoma sequence of colon carcinogenesis has not been well established. The objective of this study was to determine telomerase activity and telomere length patterns in patients with adenomatous polyps either associated or not with colorectal cancer, as well as the role of telomeric instability in the adenoma-carcinoma sequence. Patients and methods: we included in the study 14 patients who underwent surgery for colorectal cancer and/or polyps. In 6 of these patients fresh samples of tumor tissue, polyps, and normal mucosa were obtained; in the 8 remaining cases, we collected only polyps and normal mucosa. We used the fluorescent-telomeric repeat amplification protocol assay (TRAP-F to determine telomerase activity and telomere length using Southern-blot testing. Results: telomerase activity was detected in 86% of polyps and 50% of associated normal mucosa. Mean telomerase activity in polyp tissue was 5.85; in the normal mucosa it was 0.58 TPG. Mean telomere length was 6.78 Kbp and 7.78, respectively. Polyps in patients without synchronous cancer had a telomerase activity that was significantly higher (9.4 than in those with cancer (1.1. Conclusions: telomerase activity increases in the colorectal adenoma-carcinoma sequence, concurrently with a decrease in telomere length. The presence of synchronous cancer modifies telomerase activity in polyps.Objetivo: el papel de la actividad de la telomerasa y la longitud del telómero en la secuencia adenoma-carcinoma de la carcinogénesis colónica no ha sido bien establecido. El objetivo fue determinar el comportamiento de la actividad de la telomerasa y la longitud del telómero en pacientes con pólipos adenomatosos asociados o no a cáncer colorrectal y conocer el papel de la inestabilidad telomérica en la secuencia adenoma-carcinoma. Pacientes y métodos: se estudiaron 14 pacientes intervenidos de cáncer colorrectal y

  10. Fundamental mechanisms of telomerase action in yeasts and mammals: understanding telomeres and telomerase in cancer cells

    Science.gov (United States)

    Armstrong, Christine A.

    2017-01-01

    Aberrant activation of telomerase occurs in 85–90% of all cancers and underpins the ability of cancer cells to bypass their proliferative limit, rendering them immortal. The activity of telomerase is tightly controlled at multiple levels, from transcriptional regulation of the telomerase components to holoenzyme biogenesis and recruitment to the telomere, and finally activation and processivity. However, studies using cancer cell lines and other model systems have begun to reveal features of telomeres and telomerase that are unique to cancer. This review summarizes our current knowledge on the mechanisms of telomerase recruitment and activation using insights from studies in mammals and budding and fission yeasts. Finally, we discuss the differences in telomere homeostasis between normal cells and cancer cells, which may provide a foundation for telomere/telomerase targeted cancer treatments. PMID:28330934

  11. Inhibitory Effect of Arsenic Trioxide on Growth and Telomerase Activity of SMMC-7721 and BEL-7402 Hepatocarcinoma Cells and Determination of their GSH Content

    Institute of Scientific and Technical Information of China (English)

    Weiwei Ren; Hong Li; Yuan Zhang

    2006-01-01

    OBJECTIVE To explore the inhibitory effect of arsenic trioxide on growth and telomerase activity of BEL-7402 and SMMC-7721 hepatocarcinoma cells, and to measure their GSH level.METHODS Cell culture and trypan blue exclusion were used to examine the inhibitory effect of arsenic trioxide on BEL-7402 and SMMC-7721 hepatocarcinoma lines. A GSH kit and telomerase kit were used to mearsure the GSH content in cells and telomerase activity.RESULTS The growth of BEL-7402 cells was significantly inhibited at a level of 0.50 μmol/L of arsenic trioxide by 24 h. The inhibitory effect increased with time and concetration of arsenic trioxide. The telomerase activity of BEL-7402 cells was also significantly inhibited at a level of 0.50 μmol/L of arsenic trioxide by 24 h, after which the inhibitory effect increased with time. On the other hand, at 24 h of incubation a level of 2.00 μmol/L of arsenic trioxide was required to significantly inhibit growth of SMMC-7721 cells, and only after 48 h with 2.00 μmol/L of arsenic trioxide did telomerase activity significantly decline. The GSH content of the BEL-7402 and SMMC-7721 cells was 18.7±1.4 and 50.8±5.2 nmol/mg protein respectively, a significant difference.CONCLUSION Different concentrations of arsenic trioxide are required to inhibit growth and telomerase activity of SMMC-7721 and BEL-7402cells. Perhaps BEL-7402 cells are more sensitive to arsenic trioxide because of their low level of GSH content, which results in a low capacity for oxidation-reduction and poorer detoxification mechanisms in BEL-7402 cells.

  12. Telomerase - et potensielt angrepspunkt i kampen mot kreft

    OpenAIRE

    Karlstad, Ida Marie; Tell, Nicolai

    2012-01-01

    Background: Telomerase is a necessity for infinite cell division in cancer cells, and high telomerase activity is present in as much as 90 % of human cancers. Hence telomerase has become an attractive target in cancer therapy because it suggests a universal cure for cancer. We summarized research done on the vaccine GV1001 and the telomerase inhibitor Imetelstat in prostate, pancreas and lung cancer. Methods: We reviewed finished and ongoing clinical trials on GV1001 and Imetelstat; and precl...

  13. Notch1 signaling regulates the proliferation and self-renewal of human dental follicle cells by modulating the G1/S phase transition and telomerase activity.

    Directory of Open Access Journals (Sweden)

    Xuepeng Chen

    Full Text Available Multipotent human dental follicle cells (HDFCs have been intensively studied in periodontal regeneration research, yet the role of Notch1 in HDFCs has not been fully understood. The aim of the current study is to explore the role of Notch1 signaling in HDFCs self-renewal and proliferation. HDFCs were obtained from the extracted wisdom teeth from adolescent patients. Regulation of Notch1 signaling in the HDFCs was achieved by overexpressing the exogenous intracellular domain of Notch1 (ICN1 or silencing Notch1 by shRNA. The regulatory effects of Notch1 on HDFC proliferation, cell cycle distribution and the expression of cell cycle regulators were investigated through various molecular technologies, including plasmid construction, retrovirus preparation and infection, qRT-PCR, western blot, RBP-Jk luciferase reporter and cell proliferation assay. Our data clearly show that constitutively activation of Notch1 stimulates the HDFCs proliferation while inhibition of the Notch1 suppresses their proliferation in vitro. In addition, the HDFCs proliferation is associated with the increased expression of cell cycle regulators, e.g. cyclin D1, cyclin D2, cyclin D3, cyclin E1, CDK2, CDK4, CDK6, and SKP2 and the decreased expression of p27 (kip1. Moreover, our data show that the G1/S phase transition (indicating proliferation and telomerase activity (indicating self-renewal can be enhanced by overexpression of ICN1 but halted by inhibition of Notch1. Together, the current study provides evidence for the first time that Notch1 signaling regulates the proliferation and self-renewal capacity of HDFCs through modulation of the G1/S phase transition and the telomerase activity.

  14. Telomerase Cajal body protein 1 depletion inhibits telomerase trafficking to telomeres and induces G1 cell cycle arrest in A549 cells.

    Science.gov (United States)

    Yuan, Ping; Wang, Zhitian; Lv, Wang; Pan, Hui; Yang, Yunhai; Yuan, Xiaoshuai; Hu, Jian

    2014-09-01

    Telomerase Cajal body protein 1 (TCAB1) is a telomerase holoenzyme, which is markedly enriched in Cajal bodies (CBs) and facilitates the recruitment of telomerase to CBs in the S phase of the cell cycle. This recruitment is dependent on TCAB1 binding to a telomerase RNA component. The majority of cancer cells are able to grow indefinitely due to telomerase and its mechanism of trafficking to telomeres. In the present study, a certain level of TCAB1 expression in A549 human lung cells was identified and TCAB1 knockdown exhibited a potent antiproliferative effect on these cells, which was coupled with a decrease in the cell density and activity of the cellular enzymes. In addition, TCAB1-depletion was demonstrated to inhibit telomerase trafficking to telomeres in the A549 cells, leading to subsequent G1 cell cycle arrest without inducing apoptotic cell death. Overall, these observations indicated that TCAB1 may be essential for A549 cell proliferation and cell cycle regulation, and may be a potential candidate for the development of a therapeutic target for lung adenocarcinomas.

  15. Telomerase Is Essential for Zebrafish Heart Regeneration

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    Dorota Bednarek

    2015-09-01

    Full Text Available After myocardial infarction in humans, lost cardiomyocytes are replaced by an irreversible fibrotic scar. In contrast, zebrafish hearts efficiently regenerate after injury. Complete regeneration of the zebrafish heart is driven by the strong proliferation response of its cardiomyocytes to injury. Here we show that, after cardiac injury in zebrafish, telomerase becomes hyperactivated, and telomeres elongate transiently, preceding a peak of cardiomyocyte proliferation and full organ recovery. Using a telomerase-mutant zebrafish model, we found that telomerase loss drastically decreases cardiomyocyte proliferation and fibrotic tissue regression after cryoinjury and that cardiac function does not recover. The impaired cardiomyocyte proliferation response is accompanied by the absence of cardiomyocytes with long telomeres and an increased proportion of cardiomyocytes showing DNA damage and senescence characteristics. These findings demonstrate the importance of telomerase function in heart regeneration and highlight the potential of telomerase therapy as a means of stimulating cell proliferation upon myocardial infarction.

  16. Inositol hexaphosphate represses telomerase activity and translocates TERT from the nucleus in mouse and human prostate cancer cells via the deactivation of Akt and PKCalpha.

    Science.gov (United States)

    Jagadeesh, Shankar; Banerjee, Partha P

    2006-11-03

    Inositol hexaphosphate (IP6) has anti-proliferative effects on a variety of cancer cells, including prostate cancer. However, the molecular mechanism of anti-proliferative effects of IP6 is not entirely understood. Since the activation of telomerase is crucial for cells to gain immortality and proliferation ability, we examined the role of IP6 in the regulation of telomerase activity in prostate cancer cells. Here, we show that IP6 represses telomerase activity in mouse and human prostate cancer cells dose-dependently. In addition, IP6 prevents the translocation of TERT to the nucleus. Since phosphorylation of TERT by Akt and/or PKCalpha is necessary for nuclear translocation, we examined phosphorylation of Akt and PKCalpha after IP6 treatments. Our results show that IP6 inhibits phosphorylation of Akt and PKCalpha. These results show for the first time that IP6 represses telomerase activity in prostate cancer cells by posttranslational modification of TERT via the deactivation of Akt and PKCalpha.

  17. The Effect of Telomerase Antisense RNA on Telomerase Activity and Cell Proliferation of HL-60%端粒酶反义RNA 对HL-60细胞端粒酶活性及细胞增殖的影响

    Institute of Scientific and Technical Information of China (English)

    刘利; 孙秉中; 梁英民; 张传山; 张惠中; 阎严; 张方信

    2001-01-01

    Objective To study the effect of telomerase antisense RNA ontelomerase activity and cell proliferation of HL-60 cells.Methods By using lipofectin mediated DNA transfection,telomerase antisense RNA was successfully introduced into HL-60 cells.By means of TRAP、dynamics of cell growth、flucytometry the changes of HL-60 cells in aspect of telomerase activity,proliferation were detected.Results Telomerase antisense RNA can significantly inhibit the telomerase activity and the proliferation of HL-60 cells and induce the apoptosis of HL-60 cells.Conclusion It seems to be a new methods to treat leukemia by using telomerase antisense to inhibit telomerase activity and the proliferation of HL-60 cells.telomerase is a new latent target to treat leukemia.%目的 探讨端粒酶反义RNA对HL-60细胞端粒酶活性及细胞增殖的影响。方法 用脂质体介导法将pBBS212-hTR(反义端粒酶RNA真核表达载体)导入人髓性白血病细胞系HL-60中,采用TRAP法测定端粒酶活性,细胞生长动力学检测,FCM分析等方法观察其对HL-60细胞的端粒酶活性及细胞增殖影响。结果 端粒酶反义RNA能显著抑制HL-60细胞的端粒酶活性,抑制HL-60细胞的增殖并诱导其凋亡。结论 以端粒酶反义RNA抑制端粒酶活性是治疗白血病的潜在途径。

  18. Oxoisoaporphine as Potent Telomerase Inhibitor

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    Zu-Zhuang Wei

    2016-11-01

    Full Text Available Two compounds previously isolated from traditional Chinese medicine, Menispermum dauricum (DC, 6-hydroxyl-oxoisoaporphine (H-La, and 4,6-di(2-pyridinylbenzo[h]isoindolo[4,5,6-de]quinolin-8(5H-one (H-Lb, were known to have in vitro antitumor activity and to selectively bind human telomeric, c-myc, and bcl-2 G-quadruplexes (G4s. In this study, the binding properties of these two compounds to telomerase were investigated through molecular docking and telomeric repeat amplication protocol and silver staining assay (TRAP-silver staining assay. The binding energies bound to human telomerase RNA were calculated by molecular docking to be −6.43 and −9.76 kcal/mol for H-La and H-Lb, respectively. Compared with H-La, the ligand H-Lb more strongly inhibited telomerase activity in the SK-OV-3 cells model.

  19. A highly sensitive and facile graphene oxide-based nucleic acid probe: Label-free detection of telomerase activity in cancer patient's urine using AIEgens.

    Science.gov (United States)

    Ou, Xiaowen; Hong, Fan; Zhang, Zhenyu; Cheng, Yong; Zhao, Zujin; Gao, Pengcheng; Lou, Xiaoding; Xia, Fan; Wang, Shutao

    2017-03-15

    Molecular beacon (MB)-based sensing platforms that consist of a fluorogen-quencher pair play an important role in medical and biological researches. However, the synthesis of both fluorogen and quencher in the nucleic acid probes will increase the burden of organic synthesis works and induce the difficulties for precisely controlling the relative distance between fluorogen and quencher, which may lead to false-positive and false-negative results. In this work, initially we report a single labeled MB (FAM-MB, with carboxyfluorescein as fluorogen and without quencher) thus simplifies MBs with the aid of graphene oxide (GO) to detect telomerase activity. To further simplify this structure, namely label-free strategy, we design a facile, sensitive and selective platform using a label-free beacon (AIE-MB, without fluorogen and quencher), based on aggregation-induced emission fluorogen (silole-R). Upon the addition of telomerase, AIE-MB induced comb-like DNA structure leads to high aggregation of silole-R and thus exhibits strong fluorescence emission. By exploitation of this, we can detect telomerase with superior sensitivity and demonstrate their applications in bladder cancer diagnosis. Compared to single-labeled FAM-MB based telomerase activity assay, the label-free AIE-MB induced method could perform the sensitive detection with high signal-to-background ratio.

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

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    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.

  1. Proinflammatory Cytokines IL-6 and TNF-α Increased Telomerase Activity through NF-κB/STAT1/STAT3 Activation, and Withaferin A Inhibited the Signaling in Colorectal Cancer Cells

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    Seyung S. Chung

    2017-01-01

    Full Text Available There are increasing evidences of proinflammatory cytokine involvement in cancer development. Here, we found that two cytokines, IL-6 and TNF-α, activated colorectal cancer cells to be more invasive and stem-like. Combined treatment of IL-6 and TNF-α phosphorylated transcription factors STAT3 in a synergistic manner. STAT3, STAT1, and NF-κB physically interacted upon the cytokine stimulation. STAT3 was bound to the promoter region of human telomerase reverse transcriptase (hTERT. IL-6 and TNF-α stimulation further enhanced STAT3 binding affinity. Stem cell marker Oct-4 was upregulated in colorectal cancer cells upon IL-6 and TNF-α stimulation. Withaferin A, an anti-inflammatory steroidal lactone, inhibited the IL-6- and TNF-α-induced cancer cell invasion and decreased colonosphere formation. Notably, withaferin A inhibited STAT3 phosphorylation and abolished the STAT3, STAT1, and NF-κB interactions. Oct-4 expression was also downregulated by withaferin A inhibition. The binding of STAT3 to the hTERT promoter region and telomerase activity showed reduction with withaferin A treatments. Proinflammatory cytokine-induced cancer cell invasiveness is mediated by a STAT3-regulated mechanism in colorectal cancer cells. Our data suggest that withaferin A could be a promising anticancer agent that effectively inhibits the progression of colorectal cancer.

  2. Telomerase stimulates ribosomal DNA transcription under hyperproliferative conditions.

    Science.gov (United States)

    Gonzalez, Omar Garcia; Assfalg, Robin; Koch, Sylvia; Schelling, Adrian; Meena, Jitendra K; Kraus, Johann; Lechel, Andre; Katz, Sarah-Fee; Benes, Vladimir; Scharffetter-Kochanek, Karin; Kestler, Hans A; Günes, Cagatay; Iben, Sebastian

    2014-08-13

    In addition to performing its canonical function, Telomerase Reverse Transcriptase (TERT) has been shown to participate in cellular processes independent of telomerase activity. Furthermore, although TERT mainly localizes to Cajal bodies, it is also present within the nucleolus. Because the nucleolus is the site of rDNA transcription, we investigated the possible role of telomerase in regulating RNA polymerase I (Pol I). Here we show that TERT binds to rDNA and stimulates transcription by Pol I during liver regeneration and Ras-induced hyperproliferation. Moreover, the inhibition of telomerase activity by TERT- or TERC-specific RNA interference, the overexpression of dominant-negative-TERT, and the application of the telomerase inhibitor imetelstat reduce Pol I transcription and the growth of tumour cells. In vitro, telomerase can stimulate the formation of the transcription initiation complex. Our results demonstrate how non-canonical features of telomerase may direct Pol I transcription in oncogenic and regenerative hyperproliferation.

  3. 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.

  4. 贲门癌端粒酶活性表达及与p53基因突变关系的研究%Relationship of telomerase activity and p53 gene mutation in cardiac cancer

    Institute of Scientific and Technical Information of China (English)

    Jingruo li; Mengquan li; Jiangtao Li; Juntao Bao; Yunhang Zhang

    2007-01-01

    Objective: To study the relationship of the telomerase activity and the p53 gene mutation in cardiac cancer.Methods: Telomerase activity and the p53 gene mutation were detected in 46 case of cardiac cancer, peri-cancerous and 30 case of normal mucosa by TRAP-ELISA and PCR-SSCP. Results: The rate of expression of telomerase activity in cardiac cancer, peri-cancerous and normal mucosa were 82.61% (38/46), 43.48% (20/46) and 13.33% (4/30) respectively. The rate of Exon5→8 of p53 gene mutation were 39.13% (18/46), 4.35% (2/46) and 0.00% respectively. There was significant differ ence between group cancer and without cancer (P < 0.01). Mean of (A) value of telomerase is 1.89 ± 0.41 in cancer group and were 1.49 ± 0.43, 0.54 ± 0.45 respectively in peri-canvcerous and normal mucosa, there were significant differences in cancer group and group of without cancer (P < 0.05). The rate of p53 gene mutations in group of expression of telomerase activity was 44.74% (17/38), and 12.50% (1/8) in without expression of telomerase activity. There were significant differences between the two groups. Conclusion: The rate of expression of telomerase activity and mean of (A) value of telomerase in cardiac cancer were obviously higher than without cancer, which indicating telomerase activity was closely related with the occurrence of cardiac cancer. P53 gene mutation in cardiac cancer were higher than the tissue of without cancer, and the rate of p53 gene mutation in telomerase activity were obviously higher than the group of without cancer. This shows the p53 gene mutation can loss of function of suppressing cancer and prompt telomerase activity and cause the cardiac cancer.

  5. The p16(INK4A)/pRb pathway and telomerase activity define a subgroup of Ph+ adult Acute Lymphoblastic Leukemia associated with inferior outcome.

    Science.gov (United States)

    Chien, Wei W; Catallo, Régine; Chebel, Amel; Baranger, Laurence; Thomas, Xavier; Béné, Marie-Christine; Gerland, Luc M; Schmidt, Aline; Beldjord, Kheira; Klein, Nathalie; Escoffre-Barbe, Martine; Leguay, Thibaut; Huguet, Françoise; Larosa, Fabrice; Hayette, Sandrine; Plesa, Adriana; Ifrah, Norbert; Dombret, Hervé; Salles, Gilles; Chassevent, Agnès; Ffrench, Martine

    2015-04-01

    Adult Acute Lymphoblastic Leukemia (ALL) therapies have been improved by pediatric-like approaches. However, treatment failures and relapses are common and new markers are needed to identify patients with poor prognosis in prospective trials. The p16(INK4A)/CDK4-6/pRb pathway and telomerase activity, which are implicated in cell activation and aging, were analyzed to identify new prognostic markers. Proteins of the p16(INK4A)/CDK4-6/pRb pathway and telomerase activity were analyzed in 123 adult B-cell precursor (BCP) ALL cases included in the GRAALL/GRAAPH trials. We found a significantly increased expression of p16(INK4A) in BCP-ALLs with MLL rearrangement. Telomerase activity was significantly lower in Philadelphia chromosome-negative/IKAROS-deleted (BCR-ABL1(-)/IKAROS(del)) cases compared to Philadelphia chromosome-positive (BCR-ABL1+) BCP-ALLs. In BCR-ABL1+ ALLs, high CDK4 expression, phosphorylated pRb (p-pRb) and telomerase activity were significantly associated with a shorter disease-free survival (DFS) and event-free survival (EFS). Enhanced p16(INK4A) expression was only related to a significantly shorter DFS. In vitro analyses of normal stimulated lymphocytes after short- and long-term cultures demonstrated that the observed protein variations of poor prognosis in BCR-ABL1+ ALLs may be related to cell activation but not to cell aging. For these patients, our findings argue for the development of therapeutic strategies including the addition of new lymphocyte activation inhibitors to current treatments.

  6. Expression of telomerase activity in ovarian neoplasmas%卵巢肿瘤组织中端粒酶活性的表达

    Institute of Scientific and Technical Information of China (English)

    李艳; 佟玲霞; 李立安; 李红霞

    2012-01-01

    Objective: The purpose of the study was to evaluate the levels of telomerase activity in ovarian neoplasmas, analysis the signification of telomerase activity as a tumor marker in early diagnosis of ovarian neoplasmas. Methods: In the present study, telomerase activity was examined in frozen tissue specimens of malignant ovary tumor ( n = 27 ) , benign ovarian tumor ( n = 5 ) , normal tissue of malignant ovarian tumor (n = 22) and normal ovary tissue ( n = 12). The relationship was analyzed between telomerase activity and clinic - pathological parameters such as histological grade, FIGO stage, presence of distant metastasis at diagnosis of ovarian maliganant tumor. Telomerase activity was assessed by the telomeric repeat amplification protocol (TRAP). The PCR products were analyzed by electrophoresis and silver dyeing protocol. Evidence of a 6 - bp telomeric repeat ladder indicates presence of telomerase activity. The high or moderate telomerase activity was assigned to its ability to synthesize the length of DNA ladders in TRAP assay. The ladders > 100bp were graded as high level. The ladders≤99bp were graded moderate level of telomerase activity. Results: Total 66 samples ware tested. Telomarase activity could be detected in the 2 of 12 normal ovarian tissues, 1 of 5 ovarian benign tumors, 23 of 27 malignant ovarian tumors, and 12 of 22 proximal tissues. The telomrase activity rate of malignant ovarian tumors were higher than that of benign tumor and normal tissues (P = 0.0090 and 0.0000 respectively). The telomrase activity rates were 71 % and 90% in early and later stage respectively (P = 0. 269). But the higher level of telomerase activity can be detected in terminal stage of ovarian neoplasmas ( P < 0. 05 ). There were no significant differences between tumor types and histological classification. Conclusions: This study shows a high expression rate of telomerase activity in malignant ovarian tumor. There is no significant difference between early stage

  7. 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.

  8. Current Insights to Regulation and Role of Telomerase in Human Diseases

    Science.gov (United States)

    Ozturk, Mert Burak; Li, Yinghui; Tergaonkar, Vinay

    2017-01-01

    The telomerase ribonucleoprotein complex has a pivotal role in regulating the proliferation and senescence of normal somatic cells as well as cancer cells. This complex is comprised mainly of telomerase reverse transcriptase (TERT), telomerase RNA component (TERC) and other associated proteins that function to elongate telomeres localized at the end of the chromosomes. While reactivation of telomerase is a major hallmark of most cancers, together with the synergistic activation of other oncogenic signals, deficiency in telomerase and telomeric proteins might lead to aging and senescence-associated disorders. Therefore, it is critically important to understand the canonical as well as non-canonical functions of telomerase through TERT to develop a therapeutic strategy against telomerase-related diseases. In this review, we shed light on the regulation and function of telomerase, and current therapeutic strategies against telomerase in cancer and age-related diseases. PMID:28264499

  9. 端粒酶活性在肿瘤诊治中的价值%Value of Telomerase Activity on the Diagnosis and Treatment in Tumor

    Institute of Scientific and Technical Information of China (English)

    易铁男; 周云峰

    2001-01-01

    Telomerase activity highly increases in almost all huma n malignant tumors,but in benign lesions or normal tissues it dosent express e xcept germ cell and stem cell.Besides its diagnostic value,telomerase activity a ppears to be associated with tumor therapeutic effect,monitoring recurrence of t umor,predicting tumor aggressiveness.So it could be of values as a marker of tum or and a therapeutic target.This review gives a detailed presentation of value o f telomerase activity on the diagnosis and treatment in human tumor.%端粒酶几乎在所有的恶性肿瘤进程中表达,但除生殖细胞和干细 胞外良性病变和正常组织均不表达。因为它的广泛表达可作为肿瘤的标志物及癌症治疗的靶 点,使端粒酶成为目前全世界研究的热点,本文就端粒酶活性的检测与肿瘤临床的诊断、治 疗、对残存或复发癌症的监测以及病人的预后方面的研究进展作一综述。

  10. Sensitive electrochemical detection of telomerase activity using spherical nucleic acids gold nanoparticles triggered mimic-hybridization chain reaction enzyme-free dual signal amplification.

    Science.gov (United States)

    Wang, Wen-Jing; Li, Jing-Jing; Rui, Kai; Gai, Pan-Pan; Zhang, Jian-Rong; Zhu, Jun-Jie

    2015-03-03

    We report an electrochemical sensor for telomerase activity detection based on spherical nucleic acids gold nanoparticles (SNAs AuNPs) triggered mimic-hybridization chain reaction (mimic-HCR) enzyme-free dual signal amplification. In the detection strategy, SNAs AuNPs and two hairpin probes were employed. SNAs AuNPs as the primary amplification element, not only hybridized with the telomeric repeats on the electrode to amplify signal but also initiated the subsequent secondary amplification, mimic-hybridization chain reaction of two hairpin probes. If the cells' extracts were positive for telomerase activity, SNAs AuNPs could be captured on the electrode. The carried initiators could trigger an alternative hybridization reaction of two hairpin probes that yielded nicked double helices. The signal was further amplified enzyme-free by numerous hexaammineruthenium(III) chloride ([Ru(NH3)6](3+), RuHex) inserting into double-helix DNA long chain by electrostatic interaction, each of which could generate an electrochemical signal at appropriate potential. With this method, a detection limit of down to 2 HeLa cells and a dynamic range of 10-10,000 cells were achieved. Telomerase activities of different cell lines were also successfully evaluated.

  11. Comparative Analysis of Telomerase Activity in CD117+CD34+ Cardiac Telocytes with Bone Mesenchymal Stem Cells, Cardiac Fibroblasts and Cardiomyocytes

    Institute of Scientific and Technical Information of China (English)

    Yuan-Yuan Li; Shan-Shan Lu; Ting Xu; Hong-Qi Zhang; Hua Li

    2015-01-01

    Background:This study characterized the cardiac telocyte (TC) population both in vivo and in vitro,and investigated its telomerase activity related to mitosis.Methods:Using transmission electron microscopy and a phase contrast microscope,the typical morphological features of cardiac TCs were observed;by targeting the cell surface proteins CD 1 17 and CD34,CD 117+CD34+ cardiac TCs were sorted via flow cytometry and validated by immunofluorescence based on the primary cell culture.Then the optimized basal nutrient medium for selected population was examined with the cell counting kit 8.Under this conditioned medium,the process of cell division was captured,and the telomerase activity ofCD 117+CD34+ cardiac TCs was detected in comparison with bone mesenchymal stem cells (BMSCs),cardiac fibroblasts (CFBs),cardiomyocytes (CMs).Results:Cardiac TCs projected characteristic telopodes with thin segments (podomers) in alternation with dilation (podoms).In addition,64% of the primary cultured cardiac TCs were composed of CD 117+CD34+ cardiac TCs;which was verified by immunofluorescence.In a live cell imaging system,CD 117+CD34+ cardiac TCs were observed to enter into cell division in a short time,followed by an significant invagination forming across the middle of the cell body.Using a real-time quantitative telomeric-repeat amplification assay,the telomerase concentration in CD117+CD34+ cardiac TCs was obviously lower than in BMSCs and CFBs,and significantly higher than in CMs.Conclusions:Cardiac TCs represent a unique cell population and CD117+CD34+ cardiac TCs have relative low telomerase activity that differs from BMSCs,CFBs and CMs and thus they might play an important role in maintaining cardiac homeostasis.

  12. Comparative Analysis of Telomerase Activity in CD117+CD34+ Cardiac Telocytes with Bone Mesenchymal Stem Cells, Cardiac Fibroblasts and Cardiomyocytes

    Science.gov (United States)

    Li, Yuan-Yuan; Lu, Shan-Shan; Xu, Ting; Zhang, Hong-Qi; Li, Hua

    2015-01-01

    Background: This study characterized the cardiac telocyte (TC) population both in vivo and in vitro, and investigated its telomerase activity related to mitosis. Methods: Using transmission electron microscopy and a phase contrast microscope, the typical morphological features of cardiac TCs were observed; by targeting the cell surface proteins CD117 and CD34, CD117+CD34+ cardiac TCs were sorted via flow cytometry and validated by immunofluorescence based on the primary cell culture. Then the optimized basal nutrient medium for selected population was examined with the cell counting kit 8. Under this conditioned medium, the process of cell division was captured, and the telomerase activity of CD117+CD34+ cardiac TCs was detected in comparison with bone mesenchymal stem cells (BMSCs), cardiac fibroblasts (CFBs), cardiomyocytes (CMs). Results: Cardiac TCs projected characteristic telopodes with thin segments (podomers) in alternation with dilation (podoms). In addition, 64% of the primary cultured cardiac TCs were composed of CD117+CD34+ cardiac TCs; which was verified by immunofluorescence. In a live cell imaging system, CD117+CD34+ cardiac TCs were observed to enter into cell division in a short time, followed by an significant invagination forming across the middle of the cell body. Using a real-time quantitative telomeric-repeat amplification assay, the telomerase concentration in CD117+CD34+ cardiac TCs was obviously lower than in BMSCs and CFBs, and significantly higher than in CMs. Conclusions: Cardiac TCs represent a unique cell population and CD117+CD34+ cardiac TCs have relative low telomerase activity that differs from BMSCs, CFBs and CMs and thus they might play an important role in maintaining cardiac homeostasis. PMID:26168836

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

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    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.

  14. Imetelstat (a telomerase antagonist) exerts off‑target effects on the cytoskeleton.

    Science.gov (United States)

    Mender, Ilgen; Senturk, Serif; Ozgunes, Nuriman; Akcali, K Can; Kletsas, Dimitris; Gryaznov, Sergei; Can, Alp; Shay, Jerry W; Dikmen, Z Gunnur

    2013-05-01

    Telomerase is a cellular ribonucleoprotein reverse transcriptase that plays a crucial role in telomere maintenance. This enzyme is expressed in approximately 90% of human tumors, but not in the majority of normal somatic cells. imetelstat sodium (GRN163L), is a 13-mer oligonucleotide N3'→P5' thio-phosphoramidate lipid conjugate, which represents the latest generation of telomerase inhibitors targeting the template region of the human functional telomerase RNA (hTR) subunit. In preclinical trials, this compound has been found to inhibit telomerase activity in multiple cancer cell lines, as well as in vivo xenograft mouse models. Currently, GRN163L is being investigated in several clinical trials, including a phase II human non‑small cell lung cancer clinical trial, in a maintenance setting following standard doublet chemotherapy. In addition to the inhibition of telomerase activity in cancer cell lines, GRN163L causes morphological cell rounding changes, independent of hTR expression or telomere length. This leads to the loss of cell adhesion properties; however, the mechanism underlying this effect is not yet fully understood. In the present study, we observed that GRN163L treatment leads to the loss of adhesion in A549 lung cancer cells, due to decreased E-cadherin expression, leading to the disruption of the cytoskeleton through the alteration of actin, tubulin and intermediate filament organization. Consequently, the less adherent cancer cells initially cease to proliferate and are arrested in the G1 phase of the cell cycle, accompanied by decreased matrix metalloproteinase-2 (MMP-2) expression. These effects of GRN163L are independent of its telomerase catalytic activity and may increase the therapeutic efficacy of GRN163L by decreasing the adhesion, proliferation and metastatic potential of cancer cells in vivo.

  15. 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.

  16. Tracing the path of DNA substrates in active Tetrahymena telomerase holoenzyme complexes: mapping of DNA contact sites in the RNA subunit.

    Science.gov (United States)

    Goldin, Svetlana; Kertesz Rosenfeld, Karin; Manor, Haim

    2012-08-01

    Telomerase, the enzyme that extends single-stranded telomeric DNA, consists of an RNA subunit (TER) including a short template sequence, a catalytic protein (TERT) and accessory proteins. We used site-specific UV cross-linking to map the binding sites for DNA primers in TER within active Tetrahymena telomerase holoenzyme complexes. The mapping was performed at single-nucleotide resolution by a novel technique based on RNase H digestion of RNA-DNA hybrids made with overlapping complementary oligodeoxynucleotides. These data allowed tracing of the DNA path through the telomerase complexes from the template to the TERT binding element (TBE) region of TER. TBE is known to bind TERT and to be involved in the template 5'-boundary definition. Based on these findings, we propose that upstream sequences of each growing telomeric DNA chain are involved in regulation of its growth arrest at the 5'-end of the RNA template. The upstream DNA-TBE interaction may also function as an anchor for the subsequent realignment of the 3'-end of the DNA with the 3'-end of the template to enable initiation of synthesis of a new telomeric repeat.

  17. Shortened telomere length is demonstrated in T-cell subsets together with a pronounced increased telomerase activity in CD4 positive T cells from blood of patients with mycosis fungoides and parapsoriasis.

    Science.gov (United States)

    Wu, K D; Hansen, E R

    2001-10-01

    We have recently demonstrated that telomerase activity is increased and telomere length shortened in lymphocytes from peripheral blood of patients with cutaneous T-cell lymphoma. In order to determine which cell type has increased telomerase activity and shortened telomere length, CD4+, CD8+, CLA+ CD3+ and CLA- CD3+ T cells were isolated from peripheral blood of 25 patients, including 15 patients with mycosis fungoides and 10 patients with parapsoriasis. Eleven healthy individuals were used as controls; CD19+ B cells were separated from each individual as an internal control. The results showed that the increased telomerase activity was significantly predominating in the CD4+ T-cell subset. Significantly shortened telomere length was found in CD4+ and CD8+ T-cell subsets from the patients compared with the same cell subsets obtained from healthy individuals. However, no difference was observed between the subsets; CD19+ B cells collected from patients and healthy control individuals had similar telomerase activity and telomere length which was significantly different from the values found in T cells. The telomere length was significantly shorter in CLA+ CD3+ subset than in CLA- CD3+ subset. Interestingly, increased telomerase activity and shortened telomere length was also detected in CD4+ T cells from patients with parapsoriasis indicating that alteration of telomerase activity and telomere length in CD4+ T cells is an early event in the pathogenesis of cutaneous T-cell lymphoma. Thus, the results indicate that a significant high level of telomerase activity and shortened telomere length frequently occur in T cells of patients with CTCL and may reflect tumorigenesis.

  18. DHA-enriched fish oil upregulates cyclin-dependent kinase inhibitor 2A (P16(INK)) expression and downregulates telomerase activity without modulating effects of PPARγ Pro12Ala polymorphism in type 2 diabetic patients: A randomized, double-blind, placebo-controlled clinical trial.

    Science.gov (United States)

    Toupchian, Omid; Sotoudeh, Gity; Mansoori, Anahita; Abdollahi, Shima; Ali Keshavarz, Seyyed; Djalali, Mahmoud; Nasli-Esfahani, Ensieh; Alvandi, Ehsan; Chahardoli, Reza; Koohdani, Fariba

    2016-12-19

    The present study investigated the effects of docosahexaenoic acid (DHA)-enriched fish oil supplement on telomerase activity, mRNA expression of P16(INK), IL-6, and TNF-α considering Pro12Ala polymorphism in the PPARγ gene. In this double-blind randomized controlled trial, 72 PPARγ Pro12Ala polymorphism genotyped type 2 diabetic patients aged 30-70 years were randomly assigned to receive 2.4 gr of DHA-enriched fish oil or a placebo for 8 weeks. Genotyping of the Pro12Ala polymorphism in the PPARγ gene was assessed using polymerase chain reaction-restriction length polymorphism (PCR-RFLP), telomerase activity in the peripheral blood mononuclear cell (PBMC) was measured using PCR-ELISA based on the telomeric repeat amplification protocol (TRAP), and changes in the mRNA expression of P16, IL-6, and TNF-α were measured using real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). In the DHA group, telomerase activity was decreased (p = 0.001) during the intervention. In addition, between-group comparisons showed significant differences in the changes in telomerase activity (p = 0.003) and P16 mRNA expression (p = 0.028) and non-significant differences in TNF-α and IL-6 mRNA expression. The gene*DHA interaction could not affect changes in P16, IL-6, or TNF-α mRNA expression or in telomerase activity in PBMC. Short-time DHA-enriched fish oil supplementation caused increased levels of P16 expression and a decline in telomerase activity compared with the control group without modulating the effects of Pro12Ala polymorphism on the PPARγ gene. Because of the positive correlation between P16 activity and cellular senescence, the possibility of senescence stimulation by DHA is proposed. Copyright © 2016 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

  19. siRNA Downregulates Human Telomerase Reverse Transcriptase Gene and Telomere Length and Telomerase Activity in Human Colon Cancer Colo320 Cells%c-myc靶向siRNA抑制人结直肠癌Colo320细胞的增殖及下调hTERT基因表达的研究

    Institute of Scientific and Technical Information of China (English)

    黄浩; 李秀; 肖宏; 傅雷; 余兰才; 林世和; 易艳东

    2009-01-01

    Objective To study transfected shRNA of c-myc as therapeutic agent in target cell Colo320 which expressed more totomerase activity and to investigate the effect of inhibition on telomerase activity and telomere lengths and tumor cell growth. Methods A plasmid-based polymerase Ⅲ promoter system was used to deliver and express short interfering RNA (siRNA) targeting c-myc in 12o1o320 cells. The c-myc and hTERT mRNA levels were monitored by fluorescence real time reverse transcription-polymerase chain reaction, the protein levels of c-myc and hTERT were examined by Western blot analysis. Mean-while, telomere lengths and telomerase activity were measured by Southern analysis of telomere restric-tion fragment (TRF) length and PCR-ELISA. We also assessed the effects of c-myc silencing on tumor growth by DNA synthesis (3H-thymidine). Results Our data showed that expressions of c-myc and hTERT were decreased in shRNA-transfected cells, and down-regulations of c-myc and hTERT inhibited cell growth, reduced cell telomere lengths, telomerase activity. Conclusion shRNA of c-myc has the a-bility to inhibit telomerase activity, telomere lengths and cell growth with a dose dependent pattern.%目的 探讨发夹状shRNA封阻c-mye基因,抑制人结直肠癌Colo320细胞增殖、生长的状况.方法 针对原癌基因e-myc构建发夹状shRNA的真核表达质粒,并转染人结直肠癌Colo320细胞.荧光定量RT-PCR检测c-myc及细胞端粒酶逆转录酶的mRNA表达,Westemn-blot检测c-myc、hTERT蛋白表达水平.Southern blot检测端粒的长度,PCR-ELISE法检测端粒酶活性.3H-thymidine实验分析DNA合成和细胞增殖.结果 转染细胞增殖、生长皆受到抑制.同时,c-myc和hTERT的mRNA和蛋白表达显著下降,端粒的长度明显缩短,端粒酶活性降低.结论 c-myc的shRNA对人结直肠癌Co1p320细胞的增殖、端粒长度、端粒酶活性有特异性抑制作用,并呈剂量依赖关系.

  20. 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.

  1. Telomeres and telomerase: a modern fountain of youth?

    Science.gov (United States)

    de Magalhães, João Pedro; Toussaint, Olivier

    2004-01-01

    Since ageing is a universal human feature, it is not surprising that, from the Babylonian epic of Gilgamesh to Ponce de Leon seeking the "Fountain of Youth," countless people have dreamed of finding a way to avoid ageing, to no avail. Yet the search continues. In this review, we present one of the latest candidates: the enzyme telomerase, capable of elongating the tips of chromosomes, the telomeres. Research into the causes of cellular ageing established the telomeres as the molecular clock that counts the number of times cells divide and triggers cellular senescence. Herein, we review arguments both in favor and against the use of telomerase as an anti-ageing therapy. The importance of the telomeres in cellular ageing, the low or non-existent levels of telomerase activity in human tissues, and the ability of telomerase to immortalize human cells suggest that telomerase can be used as an anti-ageing therapy. On the other hand, recent experiments in mice have raised doubts whether telomerase affects organismal ageing. Results from human cells expressing telomerase have also suggested telomerase may promote tumorigenesis. We conclude that, though telomerase may be used in regenerative medicine and to treat specific diseases, it is unlikely to become a source of anti-ageing therapies.

  2. Oxoisoaporphine as Potent Telomerase Inhibitor.

    Science.gov (United States)

    Wei, Zu-Zhuang; Qin, Qi-Pin; Chen, Jia-Nian; Chen, Zhen-Feng

    2016-11-14

    Two compounds previously isolated from traditional Chinese medicine, Menispermum dauricum (DC), 6-hydroxyl-oxoisoaporphine (H-L(a)), and 4,6-di(2-pyridinyl)benzo[h]isoindolo[4,5,6-de]quinolin-8(5H)-one (H-L(b)), were known to have in vitro antitumor activity and to selectively bind human telomeric, c-myc, and bcl-2 G-quadruplexes (G4s). In this study, the binding properties of these two compounds to telomerase were investigated through molecular docking and telomeric repeat amplication protocol and silver staining assay (TRAP-silver staining assay). The binding energies bound to human telomerase RNA were calculated by molecular docking to be -6.43 and -9.76 kcal/mol for H-L(a) and H-L(b), respectively. Compared with H-L(a), the ligand H-L(b) more strongly inhibited telomerase activity in the SK-OV-3 cells model.

  3. 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.

  4. Influence of Mindfulness-Based Stress Reduction (MBSR) on Telomerase Activity in Women With Breast Cancer (BC)

    Science.gov (United States)

    Lengacher, Cecile A.; Reich, Richard R.; Kip, Kevin E.; Barta, Michelle; Ramesar, Sophia; Paterson, Carly L.; Moscoso, Manolete S.; Carranza, Irina; Budhrani, Pinky H.; Kim, Seung Joon; Park, Hyun Y.; Jacobsen, Paul B.; Schell, Michael J.; Jim, Heather S. L.; Post-White, Janice; Farias, Jerrica R.; Park, Jong Y.

    2015-01-01

    Mindfulness-based stress reduction (MBSR) reduces symptoms of depression, anxiety, and fear of recurrence among breast cancer (BC) survivors. However, the effects of MBSR (BC) on telomere length (TL) and telomerase activity (TA), known markers of cellular aging, psychological stress, and disease risk, are not known. This randomized, wait-listed, controlled study, nested within a larger trial, investigated the effects of MBSR (BC) on TL and TA. BC patients (142) with Stages 0–III cancer who had completed adjuvant treatment with radiation and/or chemotherapy at least 2 weeks prior to enrollment and within 2 years of completion of treatment with lumpectomy and/or mastectomy were randomly assigned to either a 6-week MBSR for BC program or a usual care. Assessments of TA and TL were obtained along with psychological measurements at baseline, 6 weeks, and 12 weeks after completing the MBSR(BC) program. The mean age of 142 participants was 55.3 years; 72% were non-Hispanic White; 78% had Stage I or II cancer; and 36% received both chemotherapy and radiation. In analyses adjusted for baseline TA and psychological status, TA increased steadily over 12 weeks in the MBSR(BC) group (approximately 17%) compared to essentially no increase in the control group (approximately 3%, p < .01). In contrast, no between-group difference was observed for TL (p = .92). These results provide preliminary evidence that MBSR(BC) increases TA in peripheral blood mononuclear cells from BC patients and have implications for understanding how MBSR(BC) may extend cell longevity at the cellular level. PMID:24486564

  5. A platinum(II) complex of liriodenine from traditional Chinese medicine (TCM): Cell cycle arrest, cell apoptosis induction and telomerase inhibition activity via G-quadruplex DNA stabilization.

    Science.gov (United States)

    Li, Yu-Lan; Qin, Qi-Pin; Liu, Yan-Cheng; Chen, Zhen-Feng; Liang, Hong

    2014-08-01

    Liriodenine (L), an antitumor active ingredient from the traditional Chinese medicine (TCM), Zanthoxylum nitidum, afforded a platinum(II) complex (1) of L, cis-[PtCl2(L)(DMSO)], which previously reported for its in vitro antitumor activity and intercalative binding with DNA. In this study, complex 1 was further discussed for its antitumor mechanism and structure-activity relationship, comparing with L and cisplatin. Towards the most sensitive BEL-7404 human hepatoma cells, complex 1 significantly induced cell cycle arrest at both G2/M phase and S phase. It suggests that double helix DNA is not the simplex intracellular target for 1. On the other hand, the BEL-7404 cells incubated with 1 and stained by Hoechst 33258 and AO/EB showed typical cell apoptosis in dose-dependent manner. The BEL-7404 cells incubated with 1 and stained by JC-1 were also characteristic for cell apoptosis on the loss of mitochondrial membrane potential. Furthermore, the G-quadruplex DNA binding property of complex 1 was also investigated by spectroscopic analyses, fluorescent indicator displacement (FID) assay and fluorescence resonance energy transfer (FRET) assay. The results indicated that 1 stabilized the human telomeric G4-HTG21 DNA better than L. The telomerase inhibition ratio of 1 ((62.50±0.03)%), which was examined by telomerase polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA), was much higher than L ((21.77±0.01)%). It can be ascribed to the better G4-HTG21 DNA stabilization of 1 than L. The results suggested that the nuclei, mitochondria and telomerase via G-quadruplex DNA stabilization all should be key targets for the antitumor mechanism of 1, in which the central platinum(II) played a key role.

  6. 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

  7. Telomeres and telomerase: Pharmacological targets for new anticancer strategies?

    Science.gov (United States)

    Pendino, F; Tarkanyi, I; Dudognon, C; Hillion, J; Lanotte, M; Aradi, J; Ségal-Bendirdjian, E

    2006-03-01

    Telomeres are located at the ends of eukaryotic chromosomes. Human telomerase, a cellular reverse transcriptase, is a ribonucleoprotein enzyme that catalyzes the synthesis and extension of telomeric DNA. It is composed of at least, a template RNA component (hTR; human Telomerase RNA) and a catalytic subunit, the telomerase reverse transcriptase (hTERT). The absence of telomerase is associated with telomere shortening and aging of somatic cells, while high telomerase activity is observed in over 85% of human cancer cells, strongly indicating its key role during tumorigenesis. Several details regarding telomere structure and telomerase regulation have already been elucidated, providing new targets for therapeutic exploitation. Further support for anti-telomerase approaches comes from recent studies indicating that telomerase is endowed of additional functions in the control of growth and survival of tumor cells that do not depend only on the ability of this enzyme to maintain telomere length. This observation suggests that inhibiting telomerase or its synthesis may have additional anti-proliferative and apoptosis inducing effect, independently of the reduction of telomere length during cell divisions. This article reviews the basic information about the biology of telomeres and telomerase and attempts to present various approaches that are currently under investigation to inhibit its expression and its activity. We summarize herein distinct anti-telomerase approaches like antisense strategies, reverse transcriptase inhibitors, and G-quadruplex interacting agents, and also review molecules targeting hTERT expression, such as retinoids and evaluate them for their therapeutic potential. "They conceive a certain theory, and everything has to fit into that theory. If one little fact will not fit it, they throw it aside. But it is always the facts that will not fit in that are significant". "Death on the Nile". Agatha Christie.

  8. Increased in vitro glial fibrillary acidic protein expression, telomerase activity, and telomere length after productive human immunodeficiency virus-1 infection in murine astrocytes.

    Science.gov (United States)

    Ojeda, Diego; López-Costa, Juan José; Sede, Mariano; López, Ester María; Berria, María Isabel; Quarleri, Jorge

    2014-02-01

    Although HIV-associated neurocognitive disorders (HAND) result from injury and loss of neurons, productive infection routinely takes place in cells of macrophage lineage. In such a complex context, astrocytosis induced by local chemokines/cytokines is one of the hallmarks of HIV neuropathology. Whether this sustained astrocyte activation is able to alter telomere-aging process is unknown. We hypothesized that interaction of HIV with astrocytes may impact astrocyte telomerase activity (TA) and telomere length in a scenario of astrocytic activation measured by expression of glial fibrillary acidic protein (GFAP). To test this hypothesis, cultured murine astrocytes were challenged with pseudotyped HIV/vesicular stomatitis virus (HIV/VSV) to circumvent the absence of viral receptors; and GFAP, telomerase activity, and telomere length were quantified. As an early and transient event after HIV infection, both TA activity and telomere length were significantly augmented (P telomere length, that may attenuate cell proliferation and enhance the astrocyte dysregulation, contributing to HIV neuropathogenesis. Understanding the mechanisms involved in HIV-mediated persistence by altering the telomere-related aging processes could aid in the development of therapeutic modalities for neurological complications of HIV infection.

  9. Antiproliferative effect of gold(I compound auranofin through inhibition of STAT3 and telomerase activity in MDA-MB 231 human breast cancer cells

    Directory of Open Access Journals (Sweden)

    Nam-Hoon Kim

    2013-01-01

    Full Text Available Signal transducer and activator of transcription 3 (STAT3 andtelomerase are considered attractive targets for anticancertherapy. The in vitro anticancer activity of the gold(I compoundauranofin was investigated using MDA-MB 231 human breastcancer cells, in which STAT3 is constitutively active. In cellculture, auranofin inhibited growth in a dose-dependent manner,and N-acetyl-L-cysteine (NAC, a scavenger of reactive oxygenspecies (ROS, markedly blocked the effect of auranofin.Incorporation of 5-bromo-2’-deoxyuridine into DNA andanchorage-independent cell growth on soft agar were decreasedby auranofin treatment. STAT3 phosphorylation and telomeraseactivity were also attenuated in cells exposed to auranofin, butNAC pretreatment restored STAT3 phosphorylation andtelomerase activity in these cells. These findings indicate thatauranofin exerts in vitro antitumor effects in MDA-MB 231 cellsand its activity involves inhibition of STAT3 and telomerase.Thus, auranofin shows potential as a novel anticancer drug thattargets STAT3 and telomerase. [BMB Reports 2013; 46(1: 59-64

  10. P04.24MUTATIONS OF THE TERT PROMOTER CORRELATE WITH ENHANCED TELOMERASE ACTIVATION AND PREDICT A WORSE PROGNOSIS IN PRIMARY GLIOBLASTOMA PATIENTS

    Science.gov (United States)

    Spiegl-Kreinecker, S.; Loetsch, D.; Laaber, M.; Pichler, J.; Weis, S.; Ghanim, B.; Webersinke, G.; Olschowski, A.; Berger, W.

    2014-01-01

    The stabilization of telomeres by upregulation of telomerase is compulsive for indefinite proliferation and cell immortalization therefore representing a main feature of malignant solid tumors, including gliomas. However, the mechanisms responsible for cancer-associated telomerase activation are not completely understood. Recently, defined mutations in the TERT promoter were identified in a variety of tumors, most frequent in primary glioblastomas (GBM). Presence of the mutations was associated with increased TERT expression. In the present study GBM derived tumor tissue from 126 patients operated at the Wagner Jauregg Hospital were screened for TERT promoter mutations. Subsequently the collected data were correlated with telomere associated parameters (telomerase activity, TERT mRNA expression, telomere lengths), the glioma biomarkers MGMT promoter methylation and IDH1 mutation as well as clinical parameters including patient survival. Using direct sequencing, the TERT promoter mutations (C228T, C250T) were found in 73% of tumors with predominance of C228T (72% of the mutated cases). Thirty-four (27%) samples contained none of the investigated TERT promoter mutations while mutations at both sites occurred in none of the investigated GBM cases. TERT promoter mutations were accompanied by a significant upregulation of telomerase activity (p = 0.0005) and TERT mRNA expression (p = 0.0004). Accordingly, telomere lengths of TERT promoter mutated tumors were significantly shorter compared to the TERT promoter wild-type subgroup (p = 0.001). Moreover, Kaplan-Meier survival analyses revealed a significantly shorter overall survival for GBM patients harbouring mutant tumors (p < 0.0001). In the multivariate Cox regression analysis TERT promoter mutation was found to have independent prognostic power (p = 0.049) but reached elevated significance in the interaction with age (p = 0.007). Accordingly, the prognostic quality of TERT promoter mutations was confined to the

  11. Decreased chewing activity during mouth breathing.

    Science.gov (United States)

    Hsu, H-Y; Yamaguchi, K

    2012-08-01

    This study examined the effect of mouth breathing on the strength and duration of vertical effect on the posterior teeth using related functional parameters during 3 min of gum chewing in 39 nasal breathers. A CO(2) sensor was placed over the mouth to detect expiratory airflow. When no airflow was detected from the mouth throughout the recording period, the subject was considered a nasal breather and enrolled in the study. Electromyographic (EMG) activity was recorded during 3 min of gum chewing. The protocol was repeated with the nostrils occluded. The strength of the vertical effect was obtained as integrated masseter muscle EMG activity, and the duration of vertical effect was also obtained as chewing stroke count, chewing cycle variation and EMG activity duration above baseline. Baseline activity was obtained from the isotonic EMG activity during jaw movement at 1.6 Hz without making tooth contact. The duration represented the percentage of the active period above baseline relative to the 3-min chewing period. Paired t-test and repeated analysis of variance were used to compare variables between nasal and mouth breathing. The integrated EMG activity and the duration of EMG activity above baseline, chewing stroke count and chewing cycle significantly decreased during mouth breathing compared with nasal breathing (Pmouth breathing was significantly greater than nasal breathing (PMouth breathing reduces the vertical effect on the posterior teeth, which can affect the vertical position of posterior teeth negatively, leading to malocclusion.

  12. 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.

  13. Transcriptional Regulation of Telomerase Reverse Transcriptase (TERT) by MYC

    Science.gov (United States)

    Khattar, Ekta; Tergaonkar, Vinay

    2017-01-01

    Telomerase elongates telomeres and is crucial for maintaining genomic stability. While stem cells and cancer cells display high telomerase activity, normal somatic cells lack telomerase activity primarily due to transcriptional repression of telomerase reverse transcriptase (TERT), the catalytic component of telomerase. Transcription factor binding, chromatin status as well as epigenetic modifications at the TERT promoter regulates TERT transcription. Myc is an important transcriptional regulator of TERT that directly controls its expression by promoter binding and associating with other transcription factors. In this review, we discuss the current understanding of the molecular mechanisms behind regulation of TERT transcription by Myc. We also discuss future perspectives in investigating the regulation of Myc at TERT promoter during cancer development.

  14. Evaluation of Energy Balance on Human Telomerase Reverse Transcriptase (hTERT Alternative Splicing by Semi-quantitative RT-PCR in Human Umbilical Vein Endothelial Cells

    Directory of Open Access Journals (Sweden)

    Mohaddeseh Behjati

    2017-01-01

    Full Text Available Background: Decreased high-energy phosphate level is involved in endothelial cell injury and dysfunction. Reduced telomerase activity in endothelial cells in parallel with reduced energy levels might be due to altered direction of alternative splicing machine as a complication of depleted energy during the process of atherosclerosis. Materials and Methods: Isolated human umbilical vein endothelial cells (HUVECs were treated for 24 hours by oligomycine (OM and 2-deoxy glucose (2-DG. After 24 hours, the effect of energy depletion on telomerase splicing pattern was evaluated using RT-PCR. Indeed, in both treated and untargeted cells, nitric oxide (NO and von Willebrand factor (vWF were measured. Results: ATP was depleted in treated cells by 43.9% compared with control group. We observed a slight decrease in NO levels (P = 0.09 and vWF (P = 0.395 in the setting of 49.36% ATP depletion. In both groups, no telomerase gene expression was seen. Telomerase and housekeeping gene expression were found in positive control group (colon cancer tissue and sample tissue. Conclusions: The absence of telomerase gene expression in HUVECs might be due to the mortality of these cells or the low level of telomerase gene expression in these cells under normal circumstances.

  15. Evaluation of Energy Balance on Human Telomerase Reverse Transcriptase (hTERT) Alternative Splicing by Semi-quantitative RT-PCR in Human Umbilical Vein Endothelial Cells.

    Science.gov (United States)

    Behjati, Mohaddeseh; Hashemi, Mohammad; Kazemi, Mohammad; Salehi, Mansoor; Javanmard, Shaghayegh Haghjooy

    2017-01-01

    Decreased high-energy phosphate level is involved in endothelial cell injury and dysfunction. Reduced telomerase activity in endothelial cells in parallel with reduced energy levels might be due to altered direction of alternative splicing machine as a complication of depleted energy during the process of atherosclerosis. Isolated human umbilical vein endothelial cells (HUVECs) were treated for 24 hours by oligomycine (OM) and 2-deoxy glucose (2-DG). After 24 hours, the effect of energy depletion on telomerase splicing pattern was evaluated using RT-PCR. Indeed, in both treated and untargeted cells, nitric oxide (NO) and von Willebrand factor (vWF) were measured. ATP was depleted in treated cells by 43.9% compared with control group. We observed a slight decrease in NO levels (P = 0.09) and vWF (P = 0.395) in the setting of 49.36% ATP depletion. In both groups, no telomerase gene expression was seen. Telomerase and housekeeping gene expression were found in positive control group (colon cancer tissue) and sample tissue. The absence of telomerase gene expression in HUVECs might be due to the mortality of these cells or the low level of telomerase gene expression in these cells under normal circumstances.

  16. Telomerase activity is not enough for tumor initiation in human cells

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-05

    Oct 5, 2009 ... activity may result in cell crisis of cancer and tumor regression. However, several reports ... of lung cancers (Hiyama et al., 1995), 84% of prostate cancers .... resulted in increased growth rate, cytogenetic abnor- malities and ...

  17. 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.

  18. 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.

  19. Telomerase and telomere length in pulmonary fibrosis.

    Science.gov (United States)

    Liu, Tianju; Ullenbruch, Matthew; Young Choi, Yoon; Yu, Hongfeng; Ding, Lin; Xaubet, Antoni; Pereda, Javier; Feghali-Bostwick, Carol A; Bitterman, Peter B; Henke, Craig A; Pardo, Annie; Selman, Moises; Phan, Sem H

    2013-08-01

    In addition to its expression in stem cells and many cancers, telomerase activity is transiently induced in murine bleomycin (BLM)-induced pulmonary fibrosis with increased levels of telomerase transcriptase (TERT) expression, which is essential for fibrosis. To extend these observations to human chronic fibrotic lung disease, we investigated the expression of telomerase activity in lung fibroblasts from patients with interstitial lung diseases (ILDs), including idiopathic pulmonary fibrosis (IPF). The results showed that telomerase activity was induced in more than 66% of IPF lung fibroblast samples, in comparison with less than 29% from control samples, some of which were obtained from lung cancer resections. Less than 4% of the human IPF lung fibroblast samples exhibited shortened telomeres, whereas less than 6% of peripheral blood leukocyte samples from patients with IPF or hypersensitivity pneumonitis demonstrated shortened telomeres. Moreover, shortened telomeres in late-generation telomerase RNA component knockout mice did not exert a significant effect on BLM-induced pulmonary fibrosis. In contrast, TERT knockout mice exhibited deficient fibrosis that was independent of telomere length. Finally, TERT expression was up-regulated by a histone deacetylase inhibitor, while the induction of TERT in lung fibroblasts was associated with the binding of acetylated histone H3K9 to the TERT promoter region. These findings indicate that significant telomerase induction was evident in fibroblasts from fibrotic murine lungs and a majority of IPF lung samples, whereas telomere shortening was not a common finding in the human blood and lung fibroblast samples. Notably, the animal studies indicated that the pathogenesis of pulmonary fibrosis was independent of telomere length.

  20. 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

    . Nuclear export is initiated by ROS-induced phosphorylation of tyrosine 707 within hTERT by the Src kinase family. It might be presumed that protection of mitochondria against oxidative stress is an important telomere length-independent function for telomerase in cell survival. Biotechnology companies are focused on development of therapeutic telomerase vaccines, telomerase inhibitors, and telomerase promoter-driven cell killing in oncology, have a telomerase antagonist in late preclinical studies. Anti-aging medicine-oriented groups have intervened on the market with products working on telomerase activation for a broad range of degenerative diseases in which replicative senescence or telomere dysfunction may play an important role. Since oxidative damage has been shown to shorten telomeres in tissue culture models, the adequate topical, transdermal, or systemic administration of antioxidants (such as, patented ocular administration of 1% N-acetylcarnosine lubricant eye drops in the treatment of cataracts) may be beneficial at preserving telomere lengths and delaying the onset or in treatment of disease in susceptible individuals. Therapeutic strategies toward controlled transient activation of telomerase are targeted to cells and replicative potential in cell-based therapies, tissue engineering and regenerative medicine.

  1. Disodium pentaborate decahydrate (DPD) induced apoptosis by decreasing hTERT enzyme activity and disrupting F-actin organization of prostate cancer cells.

    Science.gov (United States)

    Korkmaz, Mehmet; Avcı, Cigir Biray; Gunduz, Cumhur; Aygunes, Duygu; Erbaykent-Tepedelen, Burcu

    2014-02-01

    Animal and cell culture studies have showed that boron and its derivatives may be promising anticancer agents in prostate cancer treatment. Thus, DU145 cells were treated with disodium pentaborate decahydrate (DPD) for 24, 48, and 72 h in order to investigate the inhibitor effect and mechanisms of DPD. Then, cell proliferation, telomerase enzyme activity, actin polymerization, and apoptosis were detected by WST-1 assay, qRT-PCR, immunofluorescence labeling, and flow cytometry, respectively. We found that DPD inhibited the growth of human prostate cancer cell line DU145 at the concentration of 3.5 mM for 24 h. Our results demonstrated that 7 mM of DPD treatment prevented the telomerase enzyme activity at the rate of 38 %. Furthermore, DPD has an apoptotic effect on DU145 cells which were examined by labeling DNA breaks. With 7 mM of DPD treatment, 8, 14, and 41 % of apoptotic cells were detected for 24, 48, and 72 h, respectively. Additionally, immunofluorescence labeling showed that the normal organization of actin filaments was disrupted in DPD-exposed cells, which is accompanied by the alteration of cell shape and by apoptosis in targeted cells. Taken together, the results indicate that DPD may exert its cytotoxicity at least partly by interfering with the dynamic properties of actin polymerization and decreasing the telomerase activity. Eventually, for the first time, the results of this study showed that DPD suppressed the activity of telomerase in DU145 cells, and therefore, we suggested that DPD could be an important agent for its therapeutic potential in the treatment of prostate cancer.

  2. 苦参碱对K562细胞端粒酶hTERT-mRNA表达及其酶活性影响作用的研究%Effects of Matrine on hTERT-mRNA Expression and Telomerase Activity in K562 Cells

    Institute of Scientific and Technical Information of China (English)

    李旭芬; 张苏展; 郑树; 张行

    2001-01-01

    目的:观察苦参碱对K562细胞hTERT-mRNA表达及端粒酶活性的影响作用,并明确两者的相关性。方法:以0.1~2mg/ml苦参碱处理K562细胞48h后,RT-PCR检测其hTERT-mRNA表达,同时行TRAP-PCR-ELISA端粒酶活性检测。结果:K562细胞为一强端粒酶活性细胞株,在浓度分别为0.1、05、10、20mg/ml苦参碱作用后,K562细胞hTERT-mRNA表达明显受抑,同时伴有端粒酶活性下降,抑制率分别为0.%、13.%、91.7%和98.6%。结论:苦参碱可降低K562细胞hTERT-mRNA表达,同时伴端粒酶活性下降;端粒酶活性强度与hTERT-mRNA表达有关。%Objective:This study was designed to investigate the effects of matrine on hTERT-mRNA expression and telomerase activity in K562 cells and their relationship. Methods: The hTERT-mRNA expression was determined by RT-PCR assay in untreated and matrine-treated K562 cells, and telomerase activity was analyzed by TRAP-PCR-ELISA assay. Results: The hTERT-mRNA expression of K562 cells was significantly inhibited when treatment with matrine, while telomerase activity was decreased. Conclusion: Matrine can inhibit the hTERT-mRNA expression and telomerase activity of K562 cells. Telomerase activity might be related to the expression of hTERT-mRNA.

  3. Telomerase antagonist imetelstat inhibits esophageal cancer cell growth and increases radiation-induced DNA breaks.

    Science.gov (United States)

    Wu, Xuping; Smavadati, Shirin; Nordfjäll, Katarina; Karlsson, Krister; Qvarnström, Fredrik; Simonsson, Martin; Bergqvist, Michael; Gryaznov, Sergei; Ekman, Simon; Paulsson-Karlsson, Ylva

    2012-12-01

    Telomerase is mainly active in human tumor cells, which provides an opportunity for a therapeutic window on telomerase targeting. We sought to evaluate the potential of the thio-phosphoramidate oligonucleotide inhibitor of telomerase, imetelstat, as a drug candidate for treatment of esophageal cancer. Our results showed that imetelstat inhibited telomerase activity in a dose-dependent manner in esophageal cancer cells. After only 1 week of imetelstat treatment, a reduction of colony formation ability of esophageal cancer cells was observed. Furthermore, long-term treatment with imetelstat decreased cell growth of esophageal cancer cells with different kinetics regarding telomere lengths. Short-term imetelstat treatment also increased γ-H2AX and 53BP1 foci staining in the esophageal cancer cell lines indicating a possible induction of DNA double strand breaks (DSBs). We also found that pre-treatment with imetelstat led to increased number and size of 53BP1 foci after ionizing radiation. The increase of 53BP1 foci number was especially pronounced during the first 1h of repair whereas the increase of foci size was prominent later on. This study supports the potential of imetelstat as a therapeutic agent for the treatment of esophageal cancer.

  4. Expression and alternative splicing pattern of human telomerase reverse transcriptase in human lung cancer cells.

    Science.gov (United States)

    Fujiwara, Masachika; Kamma, Hiroshi; Wu, Wenwen; Hamasaki, Makoto; Kaneko, Setsuko; Horiguchi, Hisashi; Matsui-Horiguchi, Miwa; Satoh, Hiroaki

    2004-04-01

    Telomerase activity is generally considered to be necessary for cancer cells to avoid senescence. The expression of human telomerase reverse transcriptase (hTERT) is believed to be a rate-limiting step in telomerase activation. Recently, it has been proposed that the alternative splicing of hTERT is also involved in regulation of telomerase activity. However, the regulatory mechanism of telomerase in cancer cells has not been thoroughly investigated. To clarify it in lung cancer cells, we measured the expression of the hTERT transcript, analyzed its alternative splicing by RT-PCR, and compared it with telomerase activity and telomere length. The expression of the hTERT transcript was positively correlated with telomerase activity in lung cancer cells. Cancer cells with high telomerase activity contained 4 splicing variants of hTERT, and the full-length variant was 31.3-54.2% of the total transcripts. Cells of the TKB-20 cell line, which has extremely low telomerase activity, showed a different splicing pattern of hTERT in addition to low expression. The functional full-length variant was scarcely detected in TKB-20 cells, suggesting that the telomerase activity was repressed by alternative splicing of hTERT. Telomere length was not necessarily correlated with telomerase activity or hTERT expression in lung cancer cells. Cells of the TKB-4 cell line that also showed relatively low telomerase activity (as TKB-20 cells) had long telomeres. In conclusion, hTERT expression is regulated at both the transcriptional and post-transcriptional levels in lung cancer cells, and the alternative splicing of hTERT is involved in the control of telomerase activity.

  5. Telomerase inhibition targets clonogenic multiple myeloma cells through telomere length-dependent and independent mechanisms.

    Directory of Open Access Journals (Sweden)

    Sarah K Brennan

    Full Text Available BACKGROUND: Plasma cells constitute the majority of tumor cells in multiple myeloma (MM but lack the potential for sustained clonogenic growth. In contrast, clonotypic B cells can engraft and recapitulate disease in immunodeficient mice suggesting they serve as the MM cancer stem cell (CSC. These tumor initiating B cells also share functional features with normal stem cells such as drug resistance and self-renewal potential. Therefore, the cellular processes that regulate normal stem cells may serve as therapeutic targets in MM. Telomerase activity is required for the maintenance of normal adult stem cells, and we examined the activity of the telomerase inhibitor imetelstat against MM CSC. Moreover, we carried out both long and short-term inhibition studies to examine telomere length-dependent and independent activities. METHODOLOGY/PRINCIPAL FINDINGS: Human MM CSC were isolated from cell lines and primary clinical specimens and treated with imetelstat, a specific inhibitor of the reverse transcriptase activity of telomerase. Two weeks of exposure to imetelstat resulted in a significant reduction in telomere length and the inhibition of clonogenic MM growth both in vitro and in vivo. In addition to these relatively long-term effects, 72 hours of imetelstat treatment inhibited clonogenic growth that was associated with MM CSC differentiation based on expression of the plasma cell antigen CD138 and the stem cell marker aldehyde dehydrogenase. Short-term treatment of MM CSC also decreased the expression of genes typically expressed by stem cells (OCT3/4, SOX2, NANOG, and BMI1 as revealed by quantitative real-time PCR. CONCLUSIONS: Telomerase activity regulates the clonogenic growth of MM CSC. Moreover, reductions in MM growth following both long and short-term telomerase inhibition suggest that it impacts CSC through telomere length-dependent and independent mechanisms.

  6. Oxoisoaporphine as Potent Telomerase Inhibitor

    OpenAIRE

    Zu-Zhuang Wei; Qi-Pin Qin; Jia-Nian Chen; Zhen-Feng Chen

    2016-01-01

    Two compounds previously isolated from traditional Chinese medicine, Menispermum dauricum (DC), 6-hydroxyl-oxoisoaporphine (H-La), and 4,6-di(2-pyridinyl)benzo[h]isoindolo[4,5,6-de]quinolin-8(5H)-one (H-Lb), were known to have in vitro antitumor activity and to selectively bind human telomeric, c-myc, and bcl-2 G-quadruplexes (G4s). In this study, the binding properties of these two compounds to telomerase were investigated through molecular docking and telomeric repeat amplication protocol a...

  7. 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 biological clock of the cell, since they shorten with each cell division. Telomerase can elongate telomeres. Telomeres protect chromosome ends against being recognized as double stranded DNA breaks, and are thought to be a guard against cancer. It has furthermore been suggested that telomeres may play a role...

  8. Friend or foe? Telomerase as a pharmacological target in cancer and cardiovascular disease.

    Science.gov (United States)

    Ait-Aissa, Karima; Ebben, Johnathan D; Kadlec, Andrew O; Beyer, Andreas M

    2016-09-01

    Aging, cancer, and chronic disease have remained at the forefront of basic biological research for decades. Within this context, significant attention has been paid to the role of telomerase, the enzyme responsible for lengthening telomeres, the nucleotide sequences located at the end of chromosomes found in the nucleus. Alterations in telomere length and telomerase activity are a common denominator to the underlying pathology of these diseases. While nuclear-specific, telomere-lengthening effects of telomerase impact cellular/organismal aging and cancer development, non-canonical, extra-nuclear, and non-telomere-lengthening contributions of telomerase have only recently been described and their exact physiological implications are ill defined. Although the mechanism remains unclear, recent reports reveal that the catalytic subunit of telomerase, telomerase reverse transcriptase (TERT), regulates levels of mitochondrial-derived reactive oxygen species (mtROS), independent of its established role in the nucleus. Telomerase inhibition has been the target of chemotherapy (directed or indirectly) for over a decade now, yet no telomerase inhibitor is FDA approved and few are currently in late-stage clinical trials, possibly due to underappreciation of the distinct extra-nuclear functions of telomerase. Moreover, evaluation of telomerase-specific therapies is largely limited to the context of chemotherapy, despite reports of the beneficial effects of telomerase activation in the cardiovascular system in relation to such processes as endothelial dysfunction and myocardial infarction. Thus, there is a need for better understanding of telomerase-focused cell and organism physiology, as well as development of telomerase-specific therapies in relation to cancer and extension of these therapies to cardiovascular pathologies. This review will detail findings related to telomerase and evaluate its potential to serve as a therapeutic target.

  9. 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 ...

  10. Telomere and telomerase stability in human diseases and cancer.

    Science.gov (United States)

    Chiodi, Ilaria; Mondello, Chiara

    2016-01-01

    Telomeres are the nucleoprotein structures at the end of linear eukaryotic chromosomes required for genome stability. Telomerase is the specialized enzyme deputed to their elongation. Maintenance of a proper telomere structure, an accurate regulation of telomerase biogenesis and activity, as well as a correct telomere-telomerase interaction and a faithful telomeric DNA replication are all processes that a cell has to precisely control to safeguard its functionality. Here, we review key factors that play a role in the development of these processes and their relationship with human health.

  11. Multiple DNA Interactions Contribute to the Initiation of Telomerase Elongation.

    Science.gov (United States)

    Karademir Andersson, Ahu; Gustafsson, Cecilia; Krishnankutty, Roopesh; Cohn, Marita

    2017-07-07

    Telomerase maintains telomere length and chromosome integrity by adding short tandem repeats of single-stranded DNA to the 3' ends, via reverse transcription of a defined template region of its RNA subunit. To further understand the telomerase elongation mechanism, we studied the primer utilization and extension activity of the telomerase from the budding yeast Naumovozyma castellii (Saccharomyces castellii), which displays a processive nucleotide and repeat addition polymerization. For the efficient initiation of canonical elongation, telomerase required 4-nt primer 3' end complementarity to the template RNA. This DNA-RNA hybrid formation was highly important for the stabilization of an initiation-competent telomerase-DNA complex. Anchor site interactions with the DNA provided additional stabilization to the complex. Our studies indicate three additional separate interactions along the length of the DNA primer, each providing different and distinct contributions to the initiation event. A sequence-independent anchor site interaction acts immediately adjacent to the base-pairing 3' end, indicating a protein anchor site positioned very close to the catalytic site. Two additional anchor regions further 5' on the DNA provide sequence-specific contributions to the initiation of elongation. Remarkably, a non-telomeric sequence in the distal 25- to 32-nt region negatively influences the initiation of telomerase elongation, suggesting an anchor site with a regulatory role in the telomerase elongation decision. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. 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; Kolvraa, Steen;

    2007-01-01

    BACKGROUND: Previous studies have demonstrated that telomeres in somatic cells are not randomly distributed at the end of the chromosomes. We hypothesize that these chromosome arm specific differences in telomere length (the telomere length pattern) may be actively maintained. In this study we...... 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...... were measured using Fluorescence In Situ Hybridization (Q-FISH). RESULTS: A telomere length pattern was found to exist in primary hMSC's as well as in hMSC-telo1. This pattern is similar to what was previously found in lymphocytes and fibroblasts. The cells were then exposed to a high dose of ionizing...

  13. The catalytic and the RNA subunits of human telomerase are required to immortalize equid primary fibroblasts.

    Science.gov (United States)

    Vidale, Pamela; Magnani, Elisa; Nergadze, Solomon G; Santagostino, Marco; Cristofari, Gael; Smirnova, Alexandra; Mondello, Chiara; Giulotto, Elena

    2012-10-01

    Many human primary somatic cells can be immortalized by inducing telomerase activity through the exogenous expression of the human telomerase catalytic subunit (hTERT). This approach has been extended to the immortalization of cell lines from several mammals. Here, we show that hTERT expression is not sufficient to immortalize primary fibroblasts from three equid species, namely donkey, Burchelli's zebra and Grevy's zebra. In vitro analysis of a reconstituted telomerase composed by hTERT and an equid RNA component of telomerase (TERC) revealed a low activity of this enzyme compared to human telomerase, suggesting a low compatibility of equid and human telomerase subunits. This conclusion was also strengthened by comparison of human and equid TERC sequences, which revealed nucleotide differences in key regions for TERC and TERT interaction. We then succeeded in immortalizing equid fibroblasts by expressing hTERT and hTERC concomitantly. Expression of both human telomerase subunits led to telomerase activity and telomere elongation, indicating that human telomerase is compatible with the other equid telomerase subunits and proteins involved in telomere metabolism. The immortalization procedure described herein could be extended to primary cells from other mammals. The availability of immortal cells from endangered species could be particularly useful for obtaining new information on the organization and function of their genomes, which is relevant for their preservation.

  14. 获得性再生障碍性贫血患者端粒-端粒酶活性的变化及其意义%Changes of telomere-telomerase activity in patients with acquired aplastic anemia

    Institute of Scientific and Technical Information of China (English)

    宋佳音; 王耀春; 肖扬

    2013-01-01

    Summary To summarize (he research progress of iclomcrc length and telomerase activity in acquired aplastic anemia(Aaa). A full text database system based on PUBMED and CNK1 was adopted for searching relevant literature from 1996 to 2012 with the key words of "telomere.telomerase and acquired aplastic anemia". Criterion for data selection-The literature about advances of telomere, telomerase and acquired aplastic anemia was selected for a-nalysis. According to the standard.236 articles were analyzed. Acquired aplastic anemia is hone marrow failure syndromes that mainly results from immune-mediated destruction of hematopoiesis. About one-third of patients with Aaa have short telomeres in peripheral white blood cells.some of which have heterozygous mutations in genes encoding the telomerase components of TERT or TERC Clinical observation found that most Aaa patients with telomere shortening were insensitive to immunosuppressive therapy;the disease duration increased and the prognosis was poor. Short telomeres may cause malignant clonal diseases in the advanced .stage.such as MDS.AML. Treatment plan for these Aaa patients with shortening telomere should he adjusted. They must undergo haematopoietic stem cell transplant ( HSCT) as soon as possible,and family donors with relevant mutations must he avoided. The Aaa patients with telomere related abnormality are different from other patients regarding pathological mechanism,disease progress, treatment and prognosis. Only a small proportion of these eases could be explained by TERT or TERC mutation. Other mutation or causes may remain unknown .

  15. 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.

  16. Reptin is required for the transcription of telomerase reverse transcriptase and over-expressed in gastric cancer

    Directory of Open Access Journals (Sweden)

    Liu Tiantian

    2010-05-01

    Full Text Available Abstract Background Telomerase is activated in oncogenesis, which confers an immortal phenotype to cancer cells. The AAA + ATPase Reptin is required for telomerase biogenesis by maintaining telomerase RNA (hTER stability and is aberrantly expressed in certain cancers. Given its role in chromatin remodeling and transcription regulation, we determined the effect of Reptin on the transcription of the telomerase reverse transcriptase (hTERT gene, a key component of the telomerase complex and its expression in gastric cancer. Results Knocking down Reptin or its partner Pontin using small interfering RNA in gastric and cervical cancer cells led to significant decreases in hTERT mRNA, but hTERT promoter activity was inhibited in only Reptin-depleted cells. Reptin interacted with the c-MYC oncoprotein and its stimulatory effect on the hTERTpromoter was significantly dependent on functional E-boxes in the promoter. Moreover, Reptin bound to the hTERT proximal promoter and the loss of the Reptin occupancy led to dissociation of c-MYC from the hTERT promoter in Reptin-depleted cells. Reptin inhibition dramatically impaired clonogenic potential of gastric cancer cells by inducing cell growtharrest and over-expression of Reptin was observed in primary gastric cancer specimens. Conclusions The hTERT gene is a direct target of Reptin, and hTERT transcription requires constitutive expression of Reptin and its cooperation with c-MYC. Thus, Reptin regulates telomerase at two different levels. This finding, together with the requirementof Reptin for the clonogenic potential of cancer cells and its over-expression in gastriccancer and other solid tumors, suggests that Reptin may be a putative therapeutic target.

  17. Telomerase reverse transcriptase is required for the localization of telomerase RNA to cajal bodies and telomeres in human cancer cells.

    Science.gov (United States)

    Tomlinson, Rebecca L; Abreu, Eladio B; Ziegler, Tania; Ly, Hinh; Counter, Christopher M; Terns, Rebecca M; Terns, Michael P

    2008-09-01

    Telomere maintenance by telomerase is critical for the unlimited division potential of most human cancer cells. The two essential components of human telomerase, telomerase RNA (hTR) and telomerase reverse transcriptase (hTERT), are recruited from distinct subnuclear sites to telomeres during S phase. Throughout the remainder of the cell cycle hTR is found primarily in Cajal bodies. The localization of hTR to Cajal bodies and telomeres is specific to cancer cells where telomerase is active and is not observed in primary cells. Here we show that the trafficking of hTR to both telomeres and Cajal bodies depends on hTERT. RNA interference-mediated depletion of hTERT in cancer cells leads to loss of hTR from both Cajal bodies and telomeres without affecting hTR levels. In addition, expression of hTERT in telomerase-negative cells (including primary and ALT cancer cell lines) induces hTR to localize to both sites. Factors that did not stimulate hTR localization in our experiments include increased hTR RNA levels and Cajal body numbers, and expression of SV40 large T antigen and oncogenic Ras. Our findings suggest that the trafficking of telomerase to Cajal bodies and telomeres in cancer cells correlates with and depends on the assembly of the enzyme.

  18. 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.

  19. Turning telomerase into a Jekyll and Hyde case?

    Science.gov (United States)

    Wellinger, Raymund J

    2015-01-01

    It may be possible to coerce telomerase to incorporate modified guanine nucleotides into telomeric repeat DNA, thereby seriously compromising the functionality of the telomeres. Thus, a guanine analogue such as 6-thio-dG could turn active telomerase into a chromosome de-protecting enzyme, the opposite of what it is normally, namely a chromosome-protecting enzyme. ©2015 American Association for Cancer Research.

  20. Telomerase inhibition abolishes the tumorigenicity of pediatric ependymoma tumor-initiating cells.

    Science.gov (United States)

    Barszczyk, Mark; Buczkowicz, Pawel; Castelo-Branco, Pedro; Mack, Stephen C; Ramaswamy, Vijay; Mangerel, Joshua; Agnihotri, Sameer; Remke, Marc; Golbourn, Brian; Pajovic, Sanja; Elizabeth, Cynthia; Yu, Man; Luu, Betty; Morrison, Andrew; Adamski, Jennifer; Nethery-Brokx, Kathleen; Li, Xiao-Nan; Van Meter, Timothy; Dirks, Peter B; Rutka, James T; Taylor, Michael D; Tabori, Uri; Hawkins, Cynthia

    2014-12-01

    Pediatric ependymomas are highly recurrent tumors resistant to conventional chemotherapy. Telomerase, a ribonucleoprotein critical in permitting limitless replication, has been found to be critically important for the maintenance of tumor-initiating cells (TICs). These TICs are chemoresistant, repopulate the tumor from which they are identified, and are drivers of recurrence in numerous cancers. In this study, telomerase enzymatic activity was directly measured and inhibited to assess the therapeutic potential of targeting telomerase. Telomerase repeat amplification protocol (TRAP) (n = 36) and C-circle assay/telomere FISH/ATRX staining (n = 76) were performed on primary ependymomas to determine the prevalence and prognostic potential of telomerase activity or alternative lengthening of telomeres (ALT) as telomere maintenance mechanisms, respectively. Imetelstat, a phase 2 telomerase inhibitor, was used to elucidate the effect of telomerase inhibition on proliferation and tumorigenicity in established cell lines (BXD-1425EPN, R254), a primary TIC line (E520) and xenograft models of pediatric ependymoma. Over 60 % of pediatric ependymomas were found to rely on telomerase activity to maintain telomeres, while no ependymomas showed evidence of ALT. Children with telomerase-active tumors had reduced 5-year progression-free survival (29 ± 11 vs 64 ± 18 %; p = 0.03) and overall survival (58 ± 12 vs 83 ± 15 %; p = 0.05) rates compared to those with tumors lacking telomerase activity. Imetelstat inhibited proliferation and self-renewal by shortening telomeres and inducing senescence in vitro. In vivo, Imetelstat significantly reduced subcutaneous xenograft growth by 40 % (p = 0.03) and completely abolished the tumorigenicity of pediatric ependymoma TICs in an orthotopic xenograft model. Telomerase inhibition represents a promising therapeutic approach for telomerase-active pediatric ependymomas found to characterize high-risk ependymomas.

  1. 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.

  2. Telomerase inhibitor imetelstat has preclinical activity across the spectrum of non-small cell lung cancer oncogenotypes in a telomere length dependent manner

    OpenAIRE

    Frink, Robin E.; Peyton, Michael; Schiller, Joan H.; Gazdar, Adi F.; Shay, Jerry W.; Minna, John D.

    2016-01-01

    Telomerase was evaluated as a therapeutic oncotarget by studying the efficacy of the telomerase inhibitor imetelstat in non-small cell lung cancer (NSCLC) cell lines to determine the range of response phenotypes and identify potential biomarkers of response. A panel of 63 NSCLC cell lines was studied for telomere length and imetelstat efficacy in inhibiting colony formation and no correlation was found with patient characteristics, tumor histology, and oncogenotypes. While there was no overal...

  3. Telomerase activity in scrapings from patients with CIN and cervical cancer%宫颈上皮内瘤样病变及宫颈癌脱落细胞中端粒酶活性检测

    Institute of Scientific and Technical Information of China (English)

    乔玉环; 张梦真; 史惠蓉

    2001-01-01

    Aim:To explore the potential value of telomerase activity in cervical scrapings and to compare telomerase activity in cervical scrapings with that in frozen specimens from the same patients with CIN or cervical cancer.Methods: Telomerase activity was measured quantitatively in paired scrapings and frozen specimens respectively from 13 cases of CIN, 17 cases of cervical cancer and 11 normal cervixes by TRAP-ELISA. Results:Of the 41 scrapings, telomerase activity was detected out from 8 (61.54%) patients with CIN, 14(82.35%) patients with invasive cervical cancer and 0 in normal controls. Mean telomerase activity in CIN, cervical cancer, and control groups were(0.328±0.192),(1.329±0.259) and (0.039±0.084),respectively. There was statistically significant difference among 3 groups (p<0.01). Additionally, telomerase activity in scrapings was in accordance with that in frozen specimens. Conclusion: Our data suggest that telomerase activation is an early event and may play an important role during cervical carcinogenesis and progression. The level of telomerase activity in scrapings can mirror the cervical lesions as that in frozen tissues. It may be used as a tumor biomarker for early diagnosis, progression, prognostic evaluation of cervical cancer.%目的:探讨宫颈上皮内瘤样病变(CIN)及宫颈癌脱落细胞端粒酶活性检测的意义,并和相应活组织中端粒酶活性进行比较。方法:应用TRAR-ELISA法分别检测13例CIN、17例宫颈癌及11例正常宫颈脱落细胞和相应活组织中端粒酶活性。结果:41例脱落细胞中,8例CIN、14例宫颈癌呈端粒酶阳性表达。而正常宫颈脱落细胞中无端粒酶活性表达。CIN、宫颈癌及正常宫颈脱落细胞中端粒酶活性分别是(0.328±0.192),(1.329±0.259)和(0.039±0.084),3组比较,差异有显著性,脱落细胞中端粒酶活性和活组织中一致,呈直线正相关。结论:端粒酶激活在宫颈癌的发生发展过程

  4. 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.

  5. Telomerase regulation and the intimate relationship with aging

    Directory of Open Access Journals (Sweden)

    Morgan G

    2013-06-01

    Full Text Available Garrett Morgan1–31Department of Physiology, University of Utah School of Medicine, University of Utah, 2George E. Wahlen Department of Veterans Affairs Medical Center, 3Geriatric Research, Education and Clinical Center, VA Salt Lake City Health Care System, Salt Lake City, UT, USAAbstract: Advancing age in humans is associated with a decline in function of physiological systems, as well as the onset and progression of many chronic diseases. An ongoing focus of basic aging research is to identify biomarkers that could be used to assess the severity of age-related diseases or that could also be modulated to treat them. Telomerase is an enzyme with mechanistic links to telomere length homeostasis and cell viability. Human telomerase is a ribonucleoprotein complex that consists of its catalytic subunit (hTERT and ribonucleic acid template (hTERC. Telomerase adds de novo TTAGGG repeats to the ends of telomeres, which may prevent telomere shortening and subsequent dysfunction in certain cell compartments. Telomerase function within the cell represents a growing area of interest among biologists who study human aging, due to its potential use as a biomarker and therapeutic target for chronic disease. Here I review the basic biology of telomerase and the consequences of telomerase overexpression and deficiency in human cells and animal models. I discuss the putative role of telomerase in telomere-length homeostasis with advancing age in humans. Finally, I describe novel nontelomeric activities of telomerase related to cell viability and mitochondrial function.Keywords: chronic disease, inflammation, oxidative stress, hTERT, hTERC, mitochondria

  6. Human cells lacking coilin and Cajal bodies are proficient in telomerase assembly, trafficking and telomere maintenance

    OpenAIRE

    Chen, Yanlian; Deng, Zhiqiang; Jiang, Shuai; Hu, Qian; Liu, Haiying; Songyang, Zhou; Ma, Wenbin; Chen, Shi; Zhao, Yong

    2014-01-01

    The RNA component of human telomerase (hTR) localizes to Cajal bodies, and it has been proposed that Cajal bodies play a role in the assembly of telomerase holoenzyme and telomerase trafficking. Here, the role of Cajal bodies was examined in Human cells deficient of coilin (i.e. coilin-knockout (KO) cells), in which no Cajal bodies are detected. In coilin-KO cells, a normal level of telomerase activity is detected and interactions between core factors of holoenzyme are preserved, indicating t...

  7. Stabilization of c-myc G-Quadruplex DNA, inhibition of telomerase activity, disruption of mitochondrial functions and tumor cell apoptosis by platinum(II) complex with 9-amino-oxoisoaporphine.

    Science.gov (United States)

    Qin, Jiao-Lan; Qin, Qi-Pin; Wei, Zu-Zhuang; Yu, Yan-Cheng; Meng, Ting; Wu, Chen-Xuan; Liang, Yue-Lan; Liang, Hong; Chen, Zhen-Feng

    2016-11-29

    [Pd(L)(DMSO)Cl2] (1) and [Pt(L)(DMSO)Cl2] (2) with 9-amino-oxoisoaporphine (L), were synthesized and characterized. 1 and 2 are more selectively cytotoxic to Hep-G2 cells versus normal liver cells (HL-7702). Various experiments showed that 2 acted as telomerase inhibitors targeting G4-DNA and triggered cell apoptosis by interacting with c-myc G4-DNA. Furthermore, 2 significantly induced cell cycle arrest at both G2/M and S phase, which leading to the down-regulation of cdc25 A, cyclin D, cyclin B, cyclin A and CDK2 and the up-regulation of p53, p27, p21,chk1 and chk2. In addition, 2 also caused mitochondrial dysfunction. Taken together, we found that 2 exerted its cytotoxic activity mainly via inhibiting telomerase by interaction with c-myc G4-DNA and disruption of mitochondrial function.

  8. Prognostic impact of the number of viable circulating cells with high telomerase activity in gastric cancer patients: a prospective study.

    Science.gov (United States)

    Ito, Hiroaki; Inoue, Haruhiro; Kimura, Satoshi; Ohmori, Tohru; Ishikawa, Fumihiro; Gohda, Keigo; Sato, Jun

    2014-07-01

    The identification of circulating tumor cells (CTCs) in peripheral blood is a useful approach to estimate prognosis, monitor disease progression and measure treatment effects in several types of malignancies. We have previously used OBP-401, a telomerase-specific, replication-selective, oncolytic adenoviral agent carrying the green fluorescent protein (GFP) gene. GFP-positive cells (GFP+ cells) were counted under a fluorescence microscope. Our results showed that the number of at least 7.735 µm in diameter GFP+ cells (L-GFP+ cells) in the peripheral blood was a significant marker of prognosis in gastric cancer patients. However, tumor cells undergoing epithelial-mesenchymal transition (EMT) have been reported to be smaller in size than cells without EMT features; thus, CTCs undergoing EMT may escape detection with this technique. Therefore, in this study, we analyzed the relationship between patient outcome and the number of GFP+ cells of any size. We obtained peripheral blood samples from 65 patients with gastric cancer. After infection of OBP-401, GFP+ cells were counted and measured. The relationship between the number of GFP+ cells and surgical outcome was analyzed. The median follow-up period of the surviving patients was 36 months. A significant difference in overall survival was found between patients with 0-5 and patients with ≥6 L-GFP+ cells. No clear relationship was established between the number of small-sized GFP+ cells and patient prognosis. The number of L-GFP+ cells was significantly related to overall survival in patients with gastric cancer. The detection of L-GFP+ cells using OBP-401 may be a useful prognostic marker in gastric cancer.

  9. No difference in the rate of change in telomere length or telomerase activity in HIV-infected patients after three years of darunavir/ritonavir with and without nucleoside analogues in the MONET trial.

    Directory of Open Access Journals (Sweden)

    Ajantha Solomon

    Full Text Available OBJECTIVE: To determine whether nucleos(tide reverse transcriptase inhibitors (NRTI contribute to an accelerated loss in telomere length (TL in HIV-infected patients on antiretroviral therapy (ART. DESIGN: Substudy of randomised controlled trial. METHODS: Patients with HIV RNA <50 copies/mL on combination ART (n = 256 were randomised to darunavir/ritonavir (DRV/r 800/100 mg once daily, either as monotherapy (n = 127 or with 2 NRTIs (n = 129 for up to 144 weeks. TL and telomerase activity was quantified on stored peripheral blood mononuclear cells (PBMC; n = 124 using quantitative real time PCR. RESULTS: Patients in the sub-study had a mean age of 44 years and had received NRTI for a mean of 6.4 years (range 1-20 years. As expected, older patients have significantly shorter TL (p = 0.006, while women had significantly longer TL (p = 0.026. There was no significant association between TL and either the duration of prior NRTI treatment (p = 0.894 or the use of a PI versus NNRTI (p = 0.107. There was no significant difference between patients who continued or ceased NRTI in the mean change/year of TL or telomerase (p = 0.580 and 0.280 respectively. CONCLUSION: Continuation versus cessation of NRTI treatment was not associated with an accelerated loss in TL or telomerase activity.

  10. Human cells lacking coilin and Cajal bodies are proficient in telomerase assembly, trafficking and telomere maintenance.

    Science.gov (United States)

    Chen, Yanlian; Deng, Zhiqiang; Jiang, Shuai; Hu, Qian; Liu, Haiying; Songyang, Zhou; Ma, Wenbin; Chen, Shi; Zhao, Yong

    2015-01-01

    The RNA component of human telomerase (hTR) localizes to Cajal bodies, and it has been proposed that Cajal bodies play a role in the assembly of telomerase holoenzyme and telomerase trafficking. Here, the role of Cajal bodies was examined in Human cells deficient of coilin (i.e. coilin-knockout (KO) cells), in which no Cajal bodies are detected. In coilin-KO cells, a normal level of telomerase activity is detected and interactions between core factors of holoenzyme are preserved, indicating that telomerase assembly occurs in the absence of Cajal bodies. Moreover, dispersed hTR aggregates and forms foci specifically during S and G2 phase in coilin-KO cells. Colocalization of these hTR foci with telomeres implies proper telomerase trafficking, independent of Cajal bodies. Therefore, telomerase adds similar numbers of TTAGGG repeats to telomeres in coilin-KO and controls cells. Overexpression of TPP1-OB-fold blocks cell cycle-dependent formation of hTR foci and inhibits telomere extension. These findings suggest that telomerase assembly, trafficking and extension occur with normal efficiency in Cajal bodies deficient human cells. Thus, Cajal bodies, as such, are not essential in these processes, although it remains possible that non-coilin components of Cajal bodies and/or telomere binding proteins (e.g. TPP1) do play roles in telomerase biogenesis and telomere homeostasis.

  11. Masoprocol decreases rat lipolytic activity by decreasing the phosphorylation of HSL.

    Science.gov (United States)

    Gowri, M S; Azhar, R K; Kraemer, F B; Reaven, G M; Azhar, S

    2000-09-01

    Masoprocol (nordihydroguaiaretic acid), a lipoxygenase inhibitor isolated from the creosote bush, has been shown to decrease adipose tissue lipolytic activity both in vivo and in vitro. The present study was initiated to test the hypothesis that the decrease in lipolytic activity by masoprocol resulted from modulation of adipose tissue hormone-sensitive lipase (HSL) activity. The results indicate that oral administration of masoprocol to rats with fructose-induced hypertriglyceridemia significantly decreased their serum free fatty acid (FFA; P HSL activity were significantly lower (P HSL protein. Incubation of masoprocol with adipocytes from chow-fed rats significantly inhibited isoproterenol-induced lipolytic activity and HSL activity, associated with a decrease in the ability of isoproterenol to phosphorylate HSL. Masoprocol had no apparent effect on adipose tissue phosphatidylinositol 3-kinase activity, but okadaic acid, a serine/threonine phosphatase inhibitor, blocked the antilipolytic effect of masoprocol. The results of these in vitro and in vivo experiments suggest that the antilipolytic activity of masoprocol is secondary to its ability to inhibit HSL phosphorylation, possibly by increasing phosphatase activity. As a consequence, masoprocol administration results in lower serum FFA and TG concentrations in hypertriglyceridemic rodents.

  12. Effect of antisense human telomerase RNA on malignant behaviors of gastric carcinoma cell line SGC-7901

    Institute of Scientific and Technical Information of China (English)

    YANG Jin-liang; FANG Dian-chun; YANG Shi-ming; LUO Yuan-hui; LUO Kun-lun; LU Rong; LIU Wei-wen

    2001-01-01

    Objective: To study the effects of antisense human telomerase RNA (ahTR) transfection on the malignant behaviors of gastric carcinoma cell line SGC-7901 and its potential role in gene therapy for tumor. Methods: An antisense hTR eukaryotic expression vector containing the sequence of template region of telomere repeats was transfected into gastric carcinoma cell line SGC-7901 with liposome DOTAP. The expressions of hTR RNA and antisense hTR RNA were observed with RT-PCR, telomerase activity with PCR-ELISA. Telomere length was measured with Southern blot. Cell morphology and cellular proliferation capacity were studied with MTT assay. Cell cycle distribution and apoptotic state were observed with flow cytometry. Efficiency of clone formation in soft agar and tumorigencity in nude mice were examined and evaluated in ahTR-transfected 7901 cells, and plasmid pCL-neo transfected 7901 cells and parental 7901 cells served as control. Results: An antisense hTR eukaryotic expression vector was transfected into 7901 cells successfully. The telomerase activity in ahTR-transfected 7901 cells was decreased from 100% to about 25%, and telomere length in the cells shortened from 4.08 kb to 3.35 kb at 60 population doublings (PDs). Compared with parental 7901 and pCL-neo transfected 7901 cells, ahTR-transfected 7901 cells displayed some morphological changes, including decreased cell atypia and nucleus/cytoplasm ratio under light microscope. Furthermore, ahTR-transfected 7901 cells displayed growth inhibition, decreased invasive capacity in Borden's chamber invasive model, increased G0/G1 phase rate and apoptotic rate, and restored contact inhibition and density inhibition. Surprisingly, ahTR-transfected 7901 cells lost their capacity of clone formation in soft agar and carcinogensis in nude mice. Conclusion: Antisense hTR transfection can induce 7901 cell differentiation and reverse its malignant phenotype. This study provides an exciting approach for cancer therapy through the

  13. Activation of p53, inhibition of telomerase activity and induction of estrogen receptor beta are associated with the anti-growth effects of combination of ovarian hormones and retinoids in immortalized human mammary epithelial cells

    Directory of Open Access Journals (Sweden)

    Smith-Schneider Sallie

    2005-03-01

    Full Text Available Abstract Background A full-term pregnancy has been associated with reduced risk for developing breast cancer. In rodent models, the protective effect of pregnancy can be mimicked with a defined regimen of estrogen and progesterone combination (E/P. However, the effects of pregnancy levels of E/P in humans and their underlying mechanisms are not fully understood. In this report, we investigated the growth inhibitory effects of pregnancy levels of E/P and both natural and synthetic retinoids in an immortalized human mammary epithelial cell line, 76N TERT cell line. Results We observed that cell growth was modestly inhibited by E/P, 9-cis-retinoic acid (9-cis RA or all-trans-retinoic acid (ATRA, and strongly inhibited by N-(4-hydroxyphenyl retinamide (HPR. The growth inhibitory effects of retinoids were further increased in the presence of E/P, suggesting their effects are additive. In addition, our results showed that both E/P and retinoid treatments resulted in increased RARE and p53 gene activity. We further demonstrated that p53 and p21 protein expression were induced following the E/P and retinoid treatments. Furthermore, we demonstrated that while the telomerase activity was moderately inhibited by E/P, 9-cis RA and ATRA, it was almost completely abolished by HPR treatment. These inhibitions on telomerase activity by retinoids were potentiated by co-treatment with E/P, and correlated well with their observed growth inhibitory effects. Finally, this study provides the first evidence that estrogen receptor beta is up-regulated in response to E/P and retinoid treatments. Conclusion Taken together, our studies show that part of the anti-growth effects of E/P and retinoids is p53 dependent, and involve activation of p53 and subsequent induction of p21 expression. Inhibition of telomerase activity and up-regulation of estrogen receptor beta are also associated with the E/P- and retinoid-mediated growth inhibition. Our studies also demonstrate that

  14. 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

  15. Telomerase inhibitor imetelstat has preclinical activity across the spectrum of non-small cell lung cancer oncogenotypes in a telomere length dependent manner.

    Science.gov (United States)

    Frink, Robin E; Peyton, Michael; Schiller, Joan H; Gazdar, Adi F; Shay, Jerry W; Minna, John D

    2016-05-31

    Telomerase was evaluated as a therapeutic oncotarget by studying the efficacy of the telomerase inhibitor imetelstat in non-small cell lung cancer (NSCLC) cell lines to determine the range of response phenotypes and identify potential biomarkers of response. A panel of 63 NSCLC cell lines was studied for telomere length and imetelstat efficacy in inhibiting colony formation and no correlation was found with patient characteristics, tumor histology, and oncogenotypes. While there was no overall correlation between imetelstat efficacy with initial telomere length (ranging from 1.5 to 20 kb), the quartile of NSCLC lines with the shortest telomeres was more sensitive than the quartile with the longest telomeres. Continuous long-term treatment with imetelstat resulted in sustained telomerase inhibition, progressive telomere shortening and eventual growth inhibition in a telomere-length dependent manner. Cessation of imetelstat therapy before growth inhibition was followed by telomere regrowth. Likewise, in vivo imetelstat treatment caused tumor xenograft growth inhibition in a telomere-length dependent manner. We conclude from these preclinical studies of telomerase as an oncotarget tested by imetelstat response that imetelstat has efficacy across the entire oncogenotype spectrum of NSCLC, continuous therapy is necessary to prevent telomere regrowth, and short telomeres appears to be the best treatment biomarker.

  16. Structure and folding of the Tetrahymena telomerase RNA pseudoknot

    Science.gov (United States)

    Cash, Darian D.; Feigon, Juli

    2017-01-01

    Telomerase maintains telomere length at the ends of linear chromosomes using an integral telomerase RNA (TER) and telomerase reverse transcriptase (TERT). An essential part of TER is the template/pseudoknot domain (t/PK) which includes the template, for adding telomeric repeats, template boundary element (TBE), and pseudoknot, enclosed in a circle by stem 1. The Tetrahymena telomerase holoenzyme catalytic core (p65-TER-TERT) was recently modeled in our 9 Å resolution cryo-electron microscopy map by fitting protein and TER domains, including a solution NMR structure of the Tetrahymena pseudoknot. Here, we describe in detail the structure and folding of the isolated pseudoknot, which forms a compact structure with major groove U•A-U and novel C•G-A+ base triples. Base substitutions that disrupt the base triples reduce telomerase activity in vitro. NMR studies also reveal that the pseudoknot does not form in the context of full-length TER in the absence of TERT, due to formation of a competing structure that sequesters pseudoknot residues. The residues around the TBE remain unpaired, potentially providing access by TERT to this high affinity binding site during an early step in TERT-TER assembly. A model for the assembly pathway of the catalytic core is proposed. PMID:27899638

  17. Telomerase RNA accumulates in Cajal bodies in human cancer cells.

    Science.gov (United States)

    Zhu, Yusheng; Tomlinson, Rebecca L; Lukowiak, Andrew A; Terns, Rebecca M; Terns, Michael P

    2004-01-01

    Telomerase synthesizes telomeric DNA repeats at the ends of eukaryotic chromosomes. The RNA component of the enzyme (hTR) provides the template for telomere synthesis, which is catalyzed by telomerase reverse transcriptase (hTERT). Little is known regarding the subcellular localization of hTR and hTERT and the pathway by which telomerase is assembled. Here we report the first glimpse of the detailed subcellular localization of endogenous hTR in human cells, which we obtained by fluorescence in situ hybridization (FISH). Our studies have revealed a distinctive hTR localization pattern in cancer cells. We have found that hTR accumulates within intranuclear foci called Cajal bodies in all typical tumor-derived cell lines examined (in which telomerase is active), but not in primary or ALT cells (where little or no hTERT is present). Accumulation of hTR in the Cajal bodies of primary cells is induced when hTERT is ectopically expressed. Moreover, we report that hTERT is also found in Cajal bodies. Our data suggest that Cajal bodies are involved in the assembly and/or function of human telomerase.

  18. Telomerase efficiently elongates highly transcribing telomeres in human cancer cells.

    Directory of Open Access Journals (Sweden)

    Benjamin O Farnung

    Full Text Available RNA polymerase II transcribes the physical ends of linear eukaryotic chromosomes into a variety of long non-coding RNA molecules including telomeric repeat-containing RNA (TERRA. Since TERRA discovery, advances have been made in the characterization of TERRA biogenesis and regulation; on the contrary its associated functions remain elusive. Most of the biological roles so far proposed for TERRA are indeed based on in vitro experiments carried out using short TERRA-like RNA oligonucleotides. In particular, it has been suggested that TERRA inhibits telomerase activity. We have exploited two alternative cellular systems to test whether TERRA and/or telomere transcription influence telomerase-mediated telomere elongation in human cancer cells. In cells lacking the two DNA methyltransferases DNMT1 and DNMT3b, TERRA transcription and steady-state levels are greatly increased while telomerase is able to elongate telomeres normally. Similarly, telomerase can efficiently elongate transgenic inducible telomeres whose transcription has been experimentally augmented. Our data challenge the current hypothesis that TERRA functions as a general inhibitor of telomerase and suggest that telomere length homeostasis is maintained independently of TERRA and telomere transcription.

  19. Potent Human Telomerase Inhibitors: Molecular Dynamic Simulations, Multiple Pharmacophore-Based Virtual Screening, and Biochemical Assays.

    Science.gov (United States)

    Shirgahi Talari, Faezeh; Bagherzadeh, Kowsar; Golestanian, Sahand; Jarstfer, Michael; Amanlou, Massoud

    2015-12-28

    Telomere maintenance is a universal cancer hallmark, and small molecules that disrupt telomere maintenance generally have anticancer properties. Since the vast majority of cancer cells utilize telomerase activity for telomere maintenance, the enzyme has been considered as an anticancer drug target. Recently, rational design of telomerase inhibitors was made possible by the determination of high resolution structures of the catalytic telomerase subunit from a beetle and subsequent molecular modeling of the human telomerase complex. A hybrid strategy including docking, pharmacophore-based virtual screening, and molecular dynamics simulations (MDS) were used to identify new human telomerase inhibitors. Docking methodology was applied to investigate the ssDNA telomeric sequence and two well-known human telomerase inhibitors' (BIBR1532 and MST-312) modes of interactions with hTERT TEN domain. Subsequently molecular dynamic simulations were performed to monitor and compare hTERT TEN domain, TEN-ssDNA, TEN-BIBR1532, TEN-MST-312, and TEN-ssDNA-BIBR1532 behavior in a dynamic environment. Pharmacophore models were generated considering the inhibitors manner in the TEN domain anchor site. These exploratory studies identified several new potent inhibitors whose IC50 values were generated experimentally in a low micromolar range with the aid of biochemical assays, including both the direct telomerase and the telomeric repeat amplification protocol (TRAP) assays. The results suggest that the current models of human telomerase are useful templates for rational inhibitor design.

  20. Telomerase-independent paths to immortality in predictable cancer subtypes.

    Science.gov (United States)

    Durant, Stephen T

    2012-01-01

    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.

  1. Dynamics of human telomerase RNA structure revealed by antisense oligonucleotide technique.

    Science.gov (United States)

    Vasilkova, Daria V; Azhibek, Dulat M; Zatsepin, Timofei S; Naraikina, Yulia V; Prassolov, Vladimir S; Prokofjeva, Maria M; Zvereva, Maria I; Rubtsova, Maria P

    2013-12-01

    Telomeres are the nucleoprotein complexes that cap the linear chromosome ends. Telomerase is a ribonucleoprotein that maintains telomere length in stem, embryonic and cancer cells. Somatic cells don't contain active telomerase and telomere function as mitotic clock and telomere length determines the number of cell divisions. Telomerase RNA (TER) contains the template for telomere synthesis and serves as a structural scaffold for holoenzyme assembly. We compared different oligonucleotide based methods for telomerase RNA inhibition, such as antisense oligonucleotides, knockdown by transient siRNA transfection and silencing by miRNA derived from short expressed RNA hairpin in HEK293 cells. All of these methods were applied to different TER regions. Our results revealed that CR2/CR3 domain of TER is accessible in vitro and in vivo and could serve as an optimal site for oligonucleotide-based telomerase silencing.

  2. 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

    that the TA increased as the TRFL decreased,probably under the control of hTERT, hTERC, and TRF1.When telomerase expression was activated, only TRF2overexpression persisted to stabilize T-loop formation.Furthermore, as the TRFLR decreased to 85%, a trend of better prognosis was observed. Cox model analysis indicates a higher t/n TRFLR and distant metastasis are independent poorer prognostic factors (P = 0.035 and P = 0.042, respectively).

  3. 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.

    2015-01-01

    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 TertHigh undifferentiated spermatogonia and TertLow 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 TertHigh 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

  4. Porphyrin-aminoquinoline conjugates as telomerase inhibitors.

    Science.gov (United States)

    Maraval, Alexandrine; Franco, Sonia; Vialas, Corine; Pratviel, Geneviève; Blasco, Maria A; Meunier, Bernard

    2003-03-21

    A series of metalloporphyrins was prepared in order to target the G-quadruplex structure of telomeric DNA for the design of antitelomerase compounds. The initial cationic tetramethylpyridiniumyl porphyrin was modified by the replacement of one or two methylpyridiniumyl groups by one or two 4-aminoquinoline moieties, at the meso position, in order to increase the cell penetration and the quadruplex affinity. The porphyrins were either metallated by manganese or by nickel. The degradation of quadruplex DNA was assayed in vitro with the manganese redox-active derivatives. All porphyrins complexes were capable of inhibiting the telomerase enzyme with IC50 values in the micromolar range (TRAP assay).

  5. Telomerase expression in the glial scar of rats with spinal cord injury

    Institute of Scientific and Technical Information of China (English)

    Mingkun Yang; Weibin Sheng; Tao Xu; Kai Huang; Yanjiao Wang

    2012-01-01

    A rat model of spinal cord injury was established using the weight drop method. A cavity formed 14 days following spinal cord injury, and compact scar tissue formed by 56 days. Enzyme-linked immunosorbent assay and polymerase chain reaction enzyme-linked immunosorbent assay results demonstrated that glial fibrillary acidic protein and telomerase expression increased gradually after injury, peaked at 28 days, and then gradually decreased. Spearman rank correlation showed a positive correlation between glial fibrillary acidic protein expression and telomerase expression in the glial scar. These results suggest that telomerase promotes glial scar formation.

  6. Identification of Telomerase Components and Telomerase Regulating Factors in Yeast

    Science.gov (United States)

    1998-07-01

    required for telomere function. To further explore the mechanism of telomere replication, I identified CDCl3 and EST2 interacting proteins via yeast two...hybrid screens. Characterization of the EST2 interacting proteins may reveal additional telomerase components or regulators. STNl, a high-copy

  7. 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

  8. 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

  9. 鹿茸顶端组织端粒酶活性检测及TERT基因的差异表达%Detecting Telomerase Activity and Differential Expression Analysis of TERT Gene in Antler Tip Tissue

    Institute of Scientific and Technical Information of China (English)

    胡薇; 李沐; 李婷; 田玉华; 孟星宇; 刘宁

    2013-01-01

    为了检测梅花鹿鹿茸顶端组织不同部位的端粒酶活性及端粒酶逆转录酶( TERT )基因的mRNA表达水平,分离鹿茸顶端组织的茸皮层、间充质层及软骨层,并进行细胞培养,利用TRAP银染法测定不同部位的端粒酶活性。再利用TRIzol试剂法分别提取茸皮层、间充质和软骨细胞的总RNA,逆转录合成cDNA。根据Gen-Bank已发表的相关序列设计梅花鹿TERT基因部分序列特异引物并克隆TERT基因,采用相对荧光定量Real-time PCR法检测TERT在鹿茸顶端不同部位细胞的表达丰度。结果表明:在鹿茸顶端组织茸皮层、间充质层和软骨层均检测到了端粒酶活性,其中间充质层的端粒酶活性最高,软骨层次之,茸皮层端粒酶活性最低;而体外培养的不同代数间充质细胞的端粒酶活性无明显差异。成功获得了鹿茸组织TERT基因部分编码区cDNA序列,该基因长915 bp,编码305个AA;与牛、羊TERT基因进行同源性分析显示,核苷酸序列分别为94.89%和94.31%;氨基酸序列分别为92.16%和92.11%。相对荧光定量PCR差异分析发现,TERT基因在鹿茸顶端不同部位组织均有表达。其中,在间充质组织的表达水平高于软骨和茸皮层组织。%In order to detect the telomerase activity of different parts of top tissue of sika deer antler and mRNA expression of TERT gene, the skin of antler, mesenchymal layer and layer of cartilage were separated from the antler tip tissue and cul-tured.TRAP silver staining was improved to detect the telomerase activity of different parts.And total RNA of cartilage layer and the skin layer of antler and mesenchymal layer were isolated by TRIzol reagent to use reverse transcription for synthesizing the cDNA.According to the correlation sequences that GenBank published, sika TERT gene partial sequence special primers were designed and the gene was cloned.The relative fluorescence

  10. Synthesis and Enantiomeric Separation of a Novel Spiroketal Derivative: A Potent Human Telomerase Inhibitor with High in Vitro Anticancer Activity

    NARCIS (Netherlands)

    Fuggetta, Maria Pia; De Mico, Antonella; Cottarelli, Andrea; Morelli, Franco; Zonfrillo, Manuela; Ulgheri, Fausta; Peluso, Paola; Mannu, Alberto; Deligia, Francesco; Marchetti, Mauro; Roviello, Giovanni; Reyes Romero, Atilio; Dömling, Alexander; Spanu, Pietro

    2016-01-01

    The synthesis, the enantiomeric separation, and the characterization of new simple spiroketal derivatives have been performed. The synthesized compounds have shown a very high anticancer activity. Cell proliferation assay showed that they induce a remarkable inhibition of cell proliferation in all

  11. 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.

  12. Decreasing activated sludge thermal hydrolysis temperature reduces product colour, without decreasing degradability.

    Science.gov (United States)

    Dwyer, Jason; Starrenburg, Daniel; Tait, Stephan; Barr, Keith; Batstone, Damien J; Lant, Paul

    2008-11-01

    Activated sludges are becoming more difficult to degrade in anaerobic digesters, due to the implementation of stricter nitrogen limits, longer sludge ages, and removal of primary sedimentation units. Thermal hydrolysis is a popular method to enhance degradability of long-age activated sludge, and involves pressure and heat treatment of the process fluid (150-160 degrees C saturated steam). However, as documented in this study, in a full-scale system, the use of thermal hydrolysis produces coloured, recalcitrant compounds that can have downstream impacts (e.g., failure of UV disinfection, and increased effluent nitrogen). The coloured compound formed during thermal hydrolysis was found to be melanoidins. These are coloured recalcitrant compounds produced by polymerisation of low molecular weight intermediates, such as carbohydrates and amino compounds at elevated temperature (Maillard reaction). By decreasing the THP operating temperature from 165 degrees C to 140 degrees C, THP effluent colour decreased from 12,677 mg-PtCo L(-1) to 3837 mg-PtCo L(-1). The change in THP operating temperature from 165 degrees C to 140 degrees C was shown to have no significant impact on anaerobic biodegradability of the sludge. The rate and extent of COD biodegradation remained largely unaffected by the temperature change with an average first order hydrolysis rate of 0.19 d(-1) and conversion extent of 0.43 g-COD(CH4)g-COD(-1).

  13. Telomerase functions beyond telomere maintenance in primary cutaneous T-cell lymphoma.

    Science.gov (United States)

    Chevret, Edith; Andrique, Laetitia; Prochazkova-Carlotti, Martina; Ferrer, Jacky; Cappellen, David; Laharanne, Elodie; Idrissi, Yamina; Boettiger, Anna; Sahraoui, Wafa; Ruiz, Florian; Pham-Ledard, Anne; Vergier, Beatrice; Belloc, Francis; Dubus, Pierre; Beylot-Barry, Marie; Merlio, Jean-Philippe

    2014-03-20

    Telomere erosion may be counteracted by telomerase. Here we explored telomere length (TL) and telomerase activity (TA) in primary cutaneous T-cell lymphoma (CTCL) by using quantitative polymerase chain reaction and interphase quantitative fluorescence in situ hybridization assays. Samples from patients with Sézary syndrome (SS), transformed mycosis fungoides (T-MF), and cutaneous anaplastic large cell lymphoma were studied in parallel with corresponding cell lines to evaluate the relevance of TL and TA as target candidates for diagnostic and therapeutic purposes. Compared with controls, short telomeres were observed in aggressive CTCL subtypes such as SS and T-MF and were restricted to neoplastic cells in SS. While no genomic alteration of the hTERT (human telomerase catalytic subunit) locus was observed in patients' tumor cells, TA was detected. To understand the role of telomerase in CTCL, we manipulated its expression in CTCL cell lines. Telomerase inhibition rapidly impeded in vitro cell proliferation and led to cell death, while telomerase overexpression stimulated in vitro proliferation and clonogenicity properties and favored tumor development in immunodeficient mice. Our data indicate that, besides maintenance of TL, telomerase exerts additional functions in CTCL. Therefore, targeting these functions might represent an attractive therapeutic strategy, especially in aggressive CTCL.

  14. Stiffened yeast telomerase RNA supports RNP function in vitro and in vivo.

    Science.gov (United States)

    Lebo, Kevin J; Zappulla, David C

    2012-09-01

    The 1157-nt Saccharomyces cerevisiae telomerase RNA, TLC1, in addition to providing a 16-nt template region for reverse transcription, has been proposed to act as a scaffold for protein subunits. Although accessory subunits of the telomerase ribonucleoprotein (RNP) complex function even when their binding sites are relocated on the yeast telomerase RNA, the physical nature of the RNA scaffold has not been directly analyzed. Here we explore the structure-function organization of the yeast telomerase RNP by extensively stiffening the three long arms of TLC1, which connect essential and important accessory protein subunits Ku, Est1, and Sm(7), to its central catalytic hub. This 956-nt triple-stiff-arm TLC1 (TSA-T) reconstitutes active telomerase with TERT (Est2) in vitro. Furthermore, TSA-T functions in vivo, even maintaining longer telomeres than TLC1 on a per RNA basis. We also tested functional contributions of each stiffened arm within TSA-T and found that the stiffened Est1 and Ku arms contribute to telomere lengthening, while stiffening the terminal arm reduces telomere length and telomerase RNA abundance. The fact that yeast telomerase tolerates significant stiffening of its RNA subunit in vivo advances our understanding of the architectural and functional organization of this RNP and, more broadly, our conception of the world of lncRNPs.

  15. Decreased antitoxic activities among children with clinical episodes of malaria

    DEFF Research Database (Denmark)

    Jakobsen, P H; McKay, V; N'Jie, R

    1998-01-01

    Healthy Gambian children, children with clinical Plasmodium falciparum malaria, and children with asymptomatic P. falciparum infections were studied to investigate whether antitoxic activities may contribute to protection against malarial symptoms. Markers of inflammatory reactions, soluble tumor...... necrosis factor receptor I, and C-reactive protein were found in high concentrations in children with symptomatic P. falciparum malaria compared with levels in children with asymptomatic P. falciparum infections or in healthy children, indicating that inflammatory reactions are induced only in children...... decreased capacity to block induction of LAL activation by P. falciparum exoantigen. The decreased blocking activity was restored in the following dry season, when the children had no clinical malaria. Symptomatic children also had the highest immunoglobulin G (IgG) reactivities to conserved P. falciparum...

  16. Telomerase as an emerging target to fight cancer--opportunities and challenges for nanomedicine.

    Science.gov (United States)

    Philippi, C; Loretz, B; Schaefer, U F; Lehr, C M

    2010-09-01

    Telomerase as an enzyme is responsible for the renewal of the chromosomal ends, the so-called telomeres. By preventing them from shortening with each cell cycle, telomerase is able to inhibit cellular senescence and apoptosis. Telomerase activity, which is detectable in the majority of cancer cells, allows them to maintain their proliferative capacity. The thus obtained immortality of those cells again is a key to their malignancy. Based on these discoveries, it is obvious that telomerase inhibitors would represent an innovative approach to fight cancer, and a variety of such candidate molecules are currently in the pipeline. Telomerase inhibitors largely fall in two classes of compounds: small synthetic molecules and nucleotide-based biologicals. For several candidates, some proof of concept studies have been demonstrated, either on cell cultures or in animal models. But the same studies also revealed that inefficient delivery is largely limiting the translational step into the clinic. The most appealing feature of telomerase inhibitors, which distinguishes them from conventional anticancer drugs, is probably seen in their intrinsic non-toxicity to normal cells. Nevertheless, efficient delivery to the target cells, i.e. to the tumor, is still required. Here, some well-known biopharmaceutical problems such as insufficient solubility, permeability or even metabolic stability are frequently encountered. To address these challenges, there is a clear need for adequate delivery technologies, for example by using nanomedicines, that would allow to overcome their biopharmaceutical shortcomings and to warrant a sufficient bioavailability at the target side. This review first briefly explains the concept of telomerase and telomerase inhibition in cancer therapy. It secondly aims to provide an overview of the different currently known telomerase inhibitors. Finally, the biopharmaceutical limitations of these molecules are discussed as well as the possibilities to overcome

  17. The relationship of telomere and telomerase activity with outcome of aplastic anemia after immunesu pysessive therapy%端粒及端粒酶与再生障碍性贫血免疫抑制治疗疗效的关系

    Institute of Scientific and Technical Information of China (English)

    宋佳音; 邝丽萍; 王洋; 李勇华; 吴九龙; 张航; 李力; 王耀春; 蒋祖军

    2013-01-01

    Objective To observe the changes of telomere length and telomerase activity in patients with aplastic anemia (AA),and relationship with immunosuppressive therapy (IST) efficacy,to explore the pathogenesis of AA and the role of telomere length in evaluating immunosuppressive therapy efficacy.Method 71 cases of AA patients between September 2010 and March 2013 were enrolled into this study.3 ml peripheral blood specimens from this cohort of patients were collected to test the telomere length in peripheral blood mononuclear cell (PBMNC) with flow-FISH and detect telomerase activity with TRAP-PCR-ELISA method.Results Telomere length and age showed negative correlation (b=-0.387,P=0.001) in normal control,NSAA and SAA + VSAA groups,telomere length became shorter with the growth of age,and normal control group telomere length decreased along with the age growth slightly greater than the other two groups (NSAA,SAA+VSAA).Besides the effect of age on telomere length,(30.957±4.502) (29.510±5.911) no significant difference was observed between NSAA and SAA+VSAA groups (P=0.573),and NSAA,SAA+VSAA groups were significantly shorter than normal control group (51.086± 10.844) (P<0.01).Telomere length in NR group (25.357±4.848) was significantly lower than normal control group (51.086± 10.844) (P=0.005),telomere length in CR (32.808±4.685)/PR groups (30.334±4.464) compared with normal control group had no significant difference (P=0.517,P=0.254).Telomere length below 29.21% obviously decreased outcomes of IST.Telomerase activity had significant difference (x2=20.385,P<0.01).The telomerase activity had no significant difference interms of age and gender in three groups,multiple comparison found that telomerase activities in SAA + VSAA (0.324± 0.178) (P<0.01),and NSAA (0.234± 0.175)groups (P=0.002) were significantly higher than normal control group (0.107±0.083).Conclusion Telomere length of PBMNC in AA patients was significantly shortened than normal control group

  18. Telomere and telomerase in the initial stage of immortalization of esophageal epithelial cell

    Institute of Scientific and Technical Information of China (English)

    Zhong-Ying Shen; Li-Yan Xu; En-Min Li; Wei-Jia Cai; Min-Hua Chen; Jian Shen; Yi Zeng

    2002-01-01

    AIM: To search for the biomarker of cellular immortalization,the telomere length, telomerase activity and its subunits incultured epithelial cells of human fetal esophagus in theprocess of immortalization.METHODS: The transgenic cell line of human fetalesophageal epithelium (SHEE) was established with E6 E7genes of bt man papillomavirus (HPV) type 18 in ourlaboratory. Morphological phenotype of cultured SHEE cellsfrom the 6th to 30th passages, was examined by phasecontrast microscopy, the telomere length was assayed bySouthern blot method, and the activity of telomerase wasanalyzed by telomeric repeat amplification protocol (TRAP).Expressions of subunits of telomerase, hTR and hTERT,were assessed by RT-PCR. DNA content in cell cycle wasdetected by flow cytometry. The cell apoptosis wasexamined by electron microscopy (EM) and TUNEL label.RESULTS: SHEE cells from the 6 th to 10 th passagesshowed cellular proliferation with a good differentiation.From the 12 th to the 16 th passages, many senescent andapoptotic cells appeared, and the telomere length sharplyshortened from 23 kb to 17 kb without expression of hTERTand telornerase activity. At the 20 th passage, SHEE cellsovercame the senescence and apoptosis and restored theirproliferative activity with expression of telomerase andhTERT at low levels, but the telomere length shortenedcontinuously to the lowest of 3 kb. After the 30 th passagecells proliferation was restored by increment of cells at S andG2M phase in the cell cycle end telomerase activity expressedat high levels and with maintenance of telomere length.CONCLUSION: At the early stage of SHEE cells, telomeresare shortened without expression of telomerase and hTERTcausing cellular senescence and cell death. From the 20 thto the 30 th passages, the activation of telomerase andmaintenance of telomere length show a progressive processfor immortalization of esophageal epithelial cells. Theexpression of telomerase may constitute a biomarker fordetection of

  19. 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.

  20. PinX1 suppresses bladder urothelial carcinoma cell proliferation via the inhibition of telomerase activity and p16/cyclin D1 pathway.

    Science.gov (United States)

    Liu, Jian-Ye; Qian, Dong; He, Li-Ru; Li, Yong-Hong; Liao, Yi-Ji; Mai, Shi-Juan; Tian, Xiao-Peng; Liu, Yan-Hui; Zhang, Jia-Xing; Kung, Hsiang-Fu; Zeng, Yi-Xin; Zhou, Fang-Jian; Xie, Dan

    2013-11-23

    PIN2/TRF1-interacting telomerase inhibitor1 (PinX1) was recently suggested as a putative tumor suppressor in several types of human cancer, based on its binding to and inhibition of telomerase. Moreover, loss of PinX1 has been detected in many human malignancies. However, the possible involvement of PinX1 and its clinical/prognostic significance in urothelial carcinoma of the bladder (UCB) are unclear. The PinX1 expression profile was examined by quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, and immunohistochemistry (IHC) in UCB tissues and adjacent normal urothelial bladder epithelial tissues. PinX1 was overexpressed and silenced in UCB cell lines to determine its role in tumorigenesis, development of UCB, and the possible mechanism. PinX1 expression in UCB was significantly down-regulated at both mRNA and protein level as compared with that in normal urothelial bladder epithelial tissues. PinX1 levels were inversely correlated with tumor multiplicity, advanced N classification, high proliferation index (Ki-67), and poor survival (P p16/cyclin D1 pathway. These findings suggest that down-regulation of PinX1 play an important role in the tumorigenesis and development of UCB and that the expression of PinX1 as detected by IHC is an independent molecular marker in patients with UCB.

  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. Berberine Suppresses Adipocyte Differentiation via Decreasing CREB Transcriptional Activity.

    Directory of Open Access Journals (Sweden)

    Juan Zhang

    Full Text Available Berberine, one of the major constituents of Chinese herb Rhizoma coptidis, has been demonstrated to lower blood glucose, blood lipid, and body weight in patients with type 2 diabetes mellitus. The anti-obesity effect of berberine has been attributed to its anti-adipogenic activity. However, the underlying molecular mechanism remains largely unknown. In the present study, we found that berberine significantly suppressed the expressions of CCAAT/enhancer-binding protein (C/EBPα, peroxisome proliferators-activated receptor γ2 (PPARγ2, and other adipogenic genes in the process of adipogenesis. Berberine decreased cAMP-response element-binding protein (CREB phosphorylation and C/EBPβ expression at the early stage of 3T3-L1 preadipocyte differentiation. In addition, CREB phosphorylation and C/EBPβ expression induced by 3-isobutyl-1-methylxanthine (IBMX and forskolin were also attenuated by berberine. The binding activities of cAMP responsive element (CRE stimulated by IBMX and forskolin were inhibited by berberine. The binding of phosphorylated CREB to the promoter of C/EBPβ was abrogated by berberine after the induction of preadipocyte differentiation. These results suggest that berberine blocks adipogenesis mainly via suppressing CREB activity, which leads to a decrease in C/EBPβ-triggered transcriptional cascades.

  3. Berberine Suppresses Adipocyte Differentiation via Decreasing CREB Transcriptional Activity.

    Science.gov (United States)

    Zhang, Juan; Tang, Hongju; Deng, Ruyuan; Wang, Ning; Zhang, Yuqing; Wang, Yao; Liu, Yun; Li, Fengying; Wang, Xiao; Zhou, Libin

    2015-01-01

    Berberine, one of the major constituents of Chinese herb Rhizoma coptidis, has been demonstrated to lower blood glucose, blood lipid, and body weight in patients with type 2 diabetes mellitus. The anti-obesity effect of berberine has been attributed to its anti-adipogenic activity. However, the underlying molecular mechanism remains largely unknown. In the present study, we found that berberine significantly suppressed the expressions of CCAAT/enhancer-binding protein (C/EBP)α, peroxisome proliferators-activated receptor γ2 (PPARγ2), and other adipogenic genes in the process of adipogenesis. Berberine decreased cAMP-response element-binding protein (CREB) phosphorylation and C/EBPβ expression at the early stage of 3T3-L1 preadipocyte differentiation. In addition, CREB phosphorylation and C/EBPβ expression induced by 3-isobutyl-1-methylxanthine (IBMX) and forskolin were also attenuated by berberine. The binding activities of cAMP responsive element (CRE) stimulated by IBMX and forskolin were inhibited by berberine. The binding of phosphorylated CREB to the promoter of C/EBPβ was abrogated by berberine after the induction of preadipocyte differentiation. These results suggest that berberine blocks adipogenesis mainly via suppressing CREB activity, which leads to a decrease in C/EBPβ-triggered transcriptional cascades.

  4. Detection of telomerase activity in biopsy samples for predicting prognosis in cirrhotic patients with hepatocellular carcinoma after laparoscopic radiofrequency ablation therapy%活检组织端粒酶活性检测评价肝癌合并肝硬化腹腔镜射频消融治疗的疗效

    Institute of Scientific and Technical Information of China (English)

    Ruifang Fan; Fulu Chai; Zhipeng Han; Chenyang Wang; Xianling Guo; Xinxin Bu; Lixin Wei

    2007-01-01

    Objective:To explore the role of telomerase activity detected in biopsy samples for evaluating the efficacy of laparoscopic radiofrequency ablation (RFA) therapy in patients with hepatocellular carcinoma(HCC)and liver cirrhosis.Methods:From August 2001 to October 2004.34 cirrhotic patients with HCC were treared by laparoscopic RFA under general anesthesia.A total of 34 tumors.with a mean maximum tumor diameter of 4.0±1.0 cm.were all located on the liver surface or adjacent to the gallbladder.Laparoscopic ultrasound-guided core biopsy for liver lesions was performed before and immediately after RFA therapy.In these biopsy samples.telomerase activity was detected by the ELISA-based telomeric repeay amplificalion protocol(ELISA-TRAP)assay,and pathological examination was routinely performed.Results:Laparoscopic RFA was successfully performed in all the 34 patients.A complete tumor necrosis was achieved in all patients on the contrast-enhanced helical CT scanning one month after laparoscopic RFA.The positive rates of telomerase activity and histopathologic diagnosis in biopsy samples were 91.2%(31/34)and 100%(34/34)respectively before RFA,and 26.15%(9/34)and 0%respectively after RFA.During a median follow-up period of 35 months (range.18-51 months).the rates of local tumor recurrence at the ablation sites in post-RFA telomerase-positive and negative patients were 88.9%(8/9)and 4%(1/25)respectively(P<0.01),and the rates of distant recurrence within the livers were 0%(0/9)and 12%(3/25)respectively(P>0.05).Conclusion:For cirrhotic patients with HCC treated by laparoscopic RFA.detection of telomerase activity in biopsy samples may be useful for evaluating the therapeutic efficacy of RFA and predicting postoperative local tumor recurrence.

  5. Effects of DHA Supplementation on Vascular Function, Telomerase Activity in PBMC, Expression of Inflammatory Cytokines, and PPARγ-LXRα-ABCA1 Pathway in Patients With Type 2 Diabetes Mellitus: Study Protocol for Randomized Controlled Clinical Trial.

    Science.gov (United States)

    Toupchian, Omid; Sotoudeh, Gity; Mansoori, Anahita; Djalali, Mahmoud; Keshavarz, Seyyed Ali; Nasli-Esfahani, Ensieh; Alvandi, Ehsan; Koohdani, Fariba

    2016-07-01

    Docosahexaenoic acid (DHA), as an omega-3 fatty acid, in a natural ligand of peroxisome proliferator-activated receptors (PPARs). Regarding the combinative effects of Nutrigenomics and Nutrigenetics and due to the lack of in vivo studies conducted using natural ligands of PPARs, we aimed to evaluate the effects of DHA supplementation on vascular function, telomerase activity, and PPARγ-LXRα-ABCA1 pathway, in patients with type 2 diabetes mellitus (T2DM), based on the Pro12Ala polymorphism in PPARγ encoding gene. 72 T2DM patients (36 dominant and 36 recessive allele carriers), aged 30-70, with body mass index of 18.5 to 35 kg/m2, will be participated in this double blind randomized controlled trial. In each group, stratification will be performed based on sex and age and participants will be randomly assigned to receive 2.4 g/day DHA or placebo (paraffin) for 8 weeks. PPARγ genotyping will be carried out using PCR-RFLP method; Telomerase activity will be estimated by PCR-ELISA TRAP assay; mRNA expression levels of target genes will be assessed using real time PCR. Serum levels of ADMA, sCD163 and adiponectin, will be measured using ELISA commercial kits. The present study is designed in order to help T2DM patients to modify their health conditions based on their genetic backgrounds, and to recommend the proper food ingredients as the natural agonists for PPARs in order to prevent and treat metabolic abnormalities of the disease.

  6. Effects of DHA Supplementation on Vascular Function, Telomerase Activity in PBMC, Expression of Inflammatory Cytokines, and PPARγ-LXRα-ABCA1 Pathway in Patients With Type 2 Diabetes Mellitus: Study Protocol for Randomized Controlled Clinical Trial

    Directory of Open Access Journals (Sweden)

    Omid Toupchian

    2016-07-01

    Full Text Available Docosahexaenoic acid (DHA, as an omega-3 fatty acid, in a natural ligand of peroxisome proliferator-activated receptors (PPARs. Regarding the combinative effects of Nutrigenomics and Nutrigenetics and due to the lack of in vivo studies conducted using natural ligands of PPARs, we aimed to evaluate the effects of DHA supplementation on vascular function, telomerase activity, and PPARγ-LXRα-ABCA1 pathway, in patients with type 2 diabetes mellitus (T2DM, based on the Pro12Ala polymorphism in PPARγ encoding gene. 72 T2DM patients (36 dominant and 36 recessive allele carriers, aged 30-70, with body mass index of 18.5 to 35 kg/m2, will be participated in this double blind randomized controlled trial. In each group, stratification will be performed based on sex and age and participants will be randomly assigned to receive 2.4 g/day DHA or placebo (paraffin for 8 weeks. PPARγ genotyping will be carried out using PCR-RFLP method; Telomerase activity will be estimated by PCR-ELISA TRAP assay; mRNA expression levels of target genes will be assessed using real time PCR. Serum levels of ADMA, sCD163 and adiponectin, will be measured using ELISA commercial kits. The present study is designed in order to help T2DM patients to modify their health conditions based on their genetic backgrounds, and to recommend the proper food ingredients as the natural agonists for PPARs in order to prevent and treat metabolic abnormalities of the disease.

  7. Role of Telomerase in the Cardiovascular System

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    Mark Zurek

    2016-06-01

    Full Text Available Aging is one major risk factor for the incidence of cardiovascular diseases and the development of atherosclerosis. One important enzyme known to be involved in aging processes is Telomerase Reverse Transcriptase (TERT. After the discovery of the enzyme in humans, TERT had initially only been attributed to germ line cells, stem cells and cancer cells. However, over the last few years it has become clear that TERT is also active in cells of the cardiovascular system including cardiac myocytes, endothelial cells, smooth muscle cells and fibroblasts. Interference with the activity of this enzyme greatly contributes to cardiovascular diseases. This review will summarize the findings on the role of TERT in cardiovascular cells. Moreover, recent findings concerning TERT in different mouse models with respect to cardiovascular diseases will be described. Finally, the extranuclear functions of TERT will be covered within this review.

  8. Behaviour of telomere and telomerase during aging and regeneration in zebrafish.

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    Monique Anchelin

    Full Text Available Telomere length and telomerase activity are important factors in the pathobiology of human diseases. Age-related diseases and premature aging syndromes are characterized by short telomeres, which can compromise cell viability, whereas tumour cells can prevent telomere loss by aberrantly upregulating telomerase. The zebrafish (Danio rerio offers multiple experimental manipulation advantages over other vertebrate models and, therefore, it has been recently considered as a potential model for aging, cancer, and regeneration studies. However, it has only partially been exploited to shed light on these fundamental biological processes. The aim of this study was, therefore, to investigate telomere length and telomerase expression and activity in different strains of zebrafish obtained from different stock centres to determine whether they undergo any changes during aging and regeneration. We found that although both telomerase expression and telomere length increased from embryo to adulthood stages, they drastically declined in aged fish despite telomerase activity was detected in different tissues of old fish. In addition, we observed a weaker upregulation of telomerase expression in regenerating fins of old fish, which well correlates with their impaired regeneration capacity. Strikingly, telomeres were elongated or maintained during the fin regeneration process at all ages and after repeated amputations, likely to support high cell proliferation rates. We conclude that the expression of telomerase and telomere length are closely related during the entire life cycle of the fish and that these two parameters can be used as biomarkers of aging in zebrafish. Our results also reveal a direct relationship between the expression of telomerase, telomere length and the efficiency of tissue regeneration.

  9. 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

    2016-08-15

    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.

  10. Structural Features of the Telomerase RNA Gene in the Naked Mole Rat Heterocephalus glaber

    Science.gov (United States)

    Evfratov, S. A.; Smekalova, E. M.; Golovin, A. V.; Logvina, N. A.; Zvereva, M. I.; Dontsova, O. A.

    2014-01-01

    Telomere length, an important feature of life span control, is dependent on the activity of telomerase (a key enzyme of the telomere-length-maintaining system). Telomerase RNA is a component of telomerase and, thus, is crucial for its activity. The structures of telomerase RNA genes and their promoter regions were compared for the long-living naked mole rat and different organisms. Two rare polymorphisms in Heterocephalus glaber telomerase RNA (hgTER) were identified: A→G in the first loop of pseudoknot P2b-p3 (an equivalent of 111nt in hTR) and G→A in the scaRNA domain CR7-p8b (an equivalent of 421nt in hTR). Analysis of TER promoter regions allowed us to identify two new transcription factor binding sites. The first one is the ETS family site, which was found to be a conserved element for all the analyzed TER promoters. The second site is unique for the promoter region of TER of the naked mole rat and is a binding site for the SOX17 transcription factor. The absence of one Sp1 site in the TER promoter region of the naked small rat is an additional specific feature of the promoter area of hgTER. Such variation in the hgTER transcription regulation region and hgTER itself could provide increased telomerase activity in stem cells and an extended lifespan to H. glaber. PMID:25093110

  11. Telomerase RNA stem terminus element affects template boundary element function, telomere sequence, and shelterin binding.

    Science.gov (United States)

    Webb, Christopher J; Zakian, Virginia A

    2015-09-08

    The stem terminus element (STE), which was discovered 13 y ago in human telomerase RNA, is required for telomerase activity, yet its mode of action is unknown. We report that the Schizosaccharomyces pombe telomerase RNA, TER1 (telomerase RNA 1), also contains a STE, which is essential for telomere maintenance. Cells expressing a partial loss-of-function TER1 STE allele maintained short stable telomeres by a recombination-independent mechanism. Remarkably, the mutant telomere sequence was different from that of wild-type cells. Generation of the altered sequence is explained by reverse transcription into the template boundary element, demonstrating that the STE helps maintain template boundary element function. The altered telomeres bound less Pot1 (protection of telomeres 1) and Taz1 (telomere-associated in Schizosaccharomyces pombe 1) in vivo. Thus, the S. pombe STE, although distant from the template, ensures proper telomere sequence, which in turn promotes proper assembly of the shelterin complex.

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

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    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

  13. Herpesvirus telomerase RNA(vTR)-dependent lymphoma formation does not require interaction of vTR with telomerase reverse transcriptase (TERT).

    Science.gov (United States)

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

    2010-08-26

    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 significantly contributes to MDV-induced lymphomagenesis. As recent studies have suggested that TRs possess functions independently of telomerase activity, we investigated if the tumor-promoting properties of MDV vTR are dependent on formation of a functional telomerase complex. The P6.1 stem-loop of TR is known to mediate TR-TERT complex formation and we show here that interaction of vTR with TERT and, consequently, telomerase activity was efficiently abrogated by the disruption of the vTR P6.1 stem-loop (P6.1mut). Recombinant MDV carrying the P6.1mut stem-loop mutation were generated and tested for their behavior in the natural host in vivo. In contrast to viruses lacking vTR, all animals infected with the P6.1mut viruses developed MDV-induced lymphomas, but onset of tumor formation was significantly delayed. P6.1mut viruses induced enhanced metastasis, indicating functionality of non-complexed vTR in tumor dissemination. We discovered that RPL22, a cellular factor involved in T-cell development and virus-induced transformation, directly interacts with wild-type and mutant vTR and is, consequently, relocalized to the nucleoplasm. Our study provides the first evidence that expression of TR, in this case encoded by a herpesvirus, is pro-oncogenic in the absence of telomerase activity.

  14. Herpesvirus telomerase RNA(vTR-dependent lymphoma formation does not require interaction of vTR with telomerase reverse transcriptase (TERT.

    Directory of Open Access Journals (Sweden)

    Benedikt B Kaufer

    Full Text Available 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 significantly contributes to MDV-induced lymphomagenesis. As recent studies have suggested that TRs possess functions independently of telomerase activity, we investigated if the tumor-promoting properties of MDV vTR are dependent on formation of a functional telomerase complex. The P6.1 stem-loop of TR is known to mediate TR-TERT complex formation and we show here that interaction of vTR with TERT and, consequently, telomerase activity was efficiently abrogated by the disruption of the vTR P6.1 stem-loop (P6.1mut. Recombinant MDV carrying the P6.1mut stem-loop mutation were generated and tested for their behavior in the natural host in vivo. In contrast to viruses lacking vTR, all animals infected with the P6.1mut viruses developed MDV-induced lymphomas, but onset of tumor formation was significantly delayed. P6.1mut viruses induced enhanced metastasis, indicating functionality of non-complexed vTR in tumor dissemination. We discovered that RPL22, a cellular factor involved in T-cell development and virus-induced transformation, directly interacts with wild-type and mutant vTR and is, consequently, relocalized to the nucleoplasm. Our study provides the first evidence that expression of TR, in this case encoded by a herpesvirus, is pro-oncogenic in the absence of telomerase activity.

  15. 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

  16. 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

  17. The HSP90 inhibitor alvespimycin enhances the potency of telomerase inhibition by imetelstat in human osteosarcoma.

    Science.gov (United States)

    Hu, Yafang; Bobb, Daniel; He, Jianping; Hill, D Ashley; Dome, Jeffrey S

    2015-01-01

    The unsatisfactory outcomes for osteosarcoma necessitate novel therapeutic strategies. This study evaluated the effect of the telomerase inhibitor imetelstat in pre-clinical models of human osteosarcoma. Because the chaperone molecule HSP90 facilitates the assembly of telomerase protein, the ability of the HSP90 inhibitor alvespimycin to potentiate the effect of the telomerase inhibitor was assessed. The effect of single or combined treatment with imetelstat and alvespimycin on long-term growth was assessed in osteosarcoma cell lines (143B, HOS and MG-63) and xenografts derived from 143B cells. Results indicated that imetelstat as a single agent inhibited telomerase activity, induced telomere shortening, and inhibited growth in all 3 osteosarcoma cell lines, though the bulk cell cultures did not undergo growth arrest. Combined treatment with imetelstat and alvespimycin resulted in diminished telomerase activity and shorter telomeres compared to either agent alone as well as higher levels of γH2AX and cleaved caspase-3, indicative of increased DNA damage and apoptosis. With dual telomerase and HSP90 inhibition, complete growth arrest of bulk cell cultures was achieved. In xenograft models, all 3 treatment groups significantly inhibited tumor growth compared with the placebo-treated control group, with the greatest effect seen in the combined treatment group (imetelstat, p = 0.045, alvespimycin, p = 0.034; combined treatment, p = 0.004). In conclusion, HSP90 inhibition enhanced the effect of telomerase inhibition in pre-clinical models of osteosarcoma. Dual targeting of telomerase and HSP90 warrants further investigation as a therapeutic strategy.

  18. Foam Rolling of Quadriceps Decreases Biceps Femoris Activation.

    Science.gov (United States)

    Cavanaugh, Mark Tyler; Aboodarda, Saied Jalal; Hodgson, Daniel; Behm, David George

    2016-09-06

    Foam rolling has been shown to increase range of motion without subsequent performance impairments of the rolled muscle, however, there are no studies examining rolling effects on antagonist muscles. The objective of this study was to determine whether foam rolling the hamstrings and/or quadriceps would affect hamstrings and quadriceps activation in men and women. Recreationally active men (n=10, 25 ± 4.6 years, 180.1 ± 4.4 cm, 86.5 ± 15.7 kg) and women (n=8, 21.75 ± 3.2 years, 166.4 ± 8.8 cm, 58.9 ± 7.9 kg) had surface electromyographic activity analyzed in the dominant vastus lateralis (VL), vastus medialis (VM), and biceps femoris (BF) muscles upon a single leg landing from a hurdle jump under four conditions. Conditions included rolling of the hamstrings, quadriceps, both muscle groups and a control session. BF activation significantly decreased following quadriceps foam rolling (F(1,16) = 7.45, p = 0.015, -8.9%). There were no significant changes in quadriceps activation following hamstrings foam rolling. This might be attributed to the significantly greater levels of perceived pain with quadriceps rolling applications (F(1,18) = 39.067, p foam rolling for VL (F(6,30) = 1.31, p = 0.283) VM (F(6,30) = 1.203, p = 0.332) or BF (F(6,36) = 1.703, p = 0.199). Antagonist muscle activation may be altered following agonist foam rolling, however, it can be suggested that any changes in activation are likely a result of reciprocal inhibition due to increased agonist pain perception.

  19. Exogenous Glucocorticoids Decrease Subgenual Cingulate Activity Evoked by Sadness

    Science.gov (United States)

    Sudheimer, Keith D; Abelson, James L; Taylor, Stephan F; Martis, Brian; Welsh, Robert C; Warner, Christine; Samet, Mira; Manduzzi, Andrea; Liberzon, Israel

    2013-01-01

    The glucocorticoid hormone cortisol is known to have wide-ranging effects on a variety of physiological systems, including the morphology and physiology of the amygdala and hippocampus. Disruptions of cortisol regulation and signaling are also linked with psychiatric disorders involving emotional disturbances. Although there is much evidence to suggest a relationship between cortisol signaling and the brain physiology underlying emotion, few studies have attempted to test for direct effects of cortisol on the neurophysiology of emotion. We administered exogenous synthetic cortisol (hydrocortisone, HCT) using two different dosing regimens (25 mg/day over 4 days, 100 mg single dose), in a double-blind placebo-controlled functional magnetic resonance imaging (fMRI) study. During fMRI scanning, healthy subjects viewed images designed to induce happy, sad, and neutral emotional states. Subjective emotional reactions were collected for each experimental stimulus after fMRI scanning. Mood ratings were also collected throughout the 4 days of the study. Both dose regimens of HCT resulted in decreased subgenual cingulate activation during sadness conditions. The 25 mg/day regimen also resulted in higher arousal ratings of sad stimuli. No effects of HCT were observed on any mood ratings. Few reliable effects of HCT were observed on brain activity patterns or subjective emotional responses to stimuli that were not sad. The inhibitory effects of cortisol on sadness-induced subgenual cingulate activity may have critical relevance to the pathophysiology of major depression, as both subgenual hyperactivity and decreased sensitivity to cortisol signaling have been documented in patients with depression. PMID:23303057

  20. Dysregulated but not decreased salience network activity in schizophrenia

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    Thomas eWhite

    2013-03-01

    Full Text Available Effective estimation of the salience of environmental stimuli underlies adaptive behaviour, while related aberrance is believed to undermine rational thought processes in schizophrenia. A network including bilateral frontoinsular cortex (FIC and dorsal anterior cingulate cortex (dACC has been observed to respond to salient stimuli using functional magnetic resonance imaging (fMRI. To test the hypothesis that activity in this salience network (SN is less discriminately modulated by contextually-relevant stimuli in schizophrenia than in healthy individuals, fMRI data were collected in 20 individuals with schizophrenia and 13 matched controls during performance of a modified monetary incentive delay task. After quantitatively identifying spatial components representative of the FIC and dACC features of the SN, two principal analyses were conducted. In the first, modulation of SN activity by salience was assessed by measuring response to trial outcome. First-level general linear models were applied to individual-specific time-courses of SN activity identified using spatial independent component analysis. This analysis revealed a significant salience-by-performance-by-group interaction on the best-fit FIC component’s activity at reward outcome, whereby healthy individuals but not individuals with schizophrenia exhibited significantly greater distinction between the response to hits and misses in high salience trials than in low salience trials. The second analysis aimed to ascertain whether SN component amplitude differed between the study groups over the duration of the experiment. Independent-samples T-tests on back-projected, percent-signal-change scaled SN component images importantly showed that the groups did not differ in the overall amplitude of SN expression over the entire dataset. These findings of dysregulated but not decreased SN activity in schizophrenia provide physiological support for mechanistic conceptual frameworks of delusional

  1. Dysregulated but not decreased salience network activity in schizophrenia

    Science.gov (United States)

    White, Thomas P.; Gilleen, James; Shergill, Sukhwinder S.

    2013-01-01

    Effective estimation of the salience of environmental stimuli underlies adaptive behavior, while related aberrance is believed to undermine rational thought processes in schizophrenia. A network including bilateral frontoinsular cortex (FIC) and dorsal anterior cingulate cortex (dACC) has been observed to respond to salient stimuli using functional magnetic resonance imaging (fMRI). To test the hypothesis that activity in this salience network (SN) is less discriminately modulated by contextually-relevant stimuli in schizophrenia than in healthy individuals, fMRI data were collected in 20 individuals with schizophrenia and 13 matched controls during performance of a modified monetary incentive delay (MID) task. After quantitatively identifying spatial components representative of the FIC and dACC features of the SN, two principal analyses were conducted. In the first, modulation of SN activity by salience was assessed by measuring response to trial outcome. First-level general linear models were applied to individual-specific time-courses of SN activity identified using spatial independent component analysis (ICA). This analysis revealed a significant salience-by-performance-by-group interaction on the best-fit FIC component's activity at trial outcome, whereby healthy individuals but not individuals with schizophrenia exhibited greater distinction between the response to hits and misses in high salience trials than in low salience trials. The second analysis aimed to ascertain whether SN component amplitude differed between the study groups over the duration of the experiment. Independent-samples T-tests on back-projected, percent-signal-change scaled SN component images importantly showed that the groups did not differ in the overall amplitude of SN expression over the entire dataset. These findings of dysregulated but not decreased SN activity in schizophrenia provide physiological support for mechanistic conceptual frameworks of delusional thought formation

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

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    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.

  3. Decreased dopamine activity predicts relapse in methamphetamine abusers

    Energy Technology Data Exchange (ETDEWEB)

    Wang G. J.; Wang, G.-J.; Smith, L.; Volkow, N.D.; Telang, F.; Logan, J.; Tomasi, D.; Wong, C.T.; Hoffman, W.; Jayne, M.; Alia-Klein, N.; Thanos, P.; Fowler, J.S.

    2011-01-20

    Studies in methamphetamine (METH) abusers showed that the decreases in brain dopamine (DA) function might recover with protracted detoxification. However, the extent to which striatal DA function in METH predicts recovery has not been evaluated. Here we assessed whether striatal DA activity in METH abusers is associated with clinical outcomes. Brain DA D2 receptor (D2R) availability was measured with positron emission tomography and [{sup 11}C]raclopride in 16 METH abusers, both after placebo and after challenge with 60 mg oral methylphenidate (MPH) (to measure DA release) to assess whether it predicted clinical outcomes. For this purpose, METH abusers were tested within 6 months of last METH use and then followed up for 9 months of abstinence. In parallel, 15 healthy controls were tested. METH abusers had lower D2R availability in caudate than in controls. Both METH abusers and controls showed decreased striatal D2R availability after MPH and these decreases were smaller in METH than in controls in left putamen. The six METH abusers who relapsed during the follow-up period had lower D2R availability in dorsal striatum than in controls, and had no D2R changes after MPH challenge. The 10 METH abusers who completed detoxification did not differ from controls neither in striatal D2R availability nor in MPH-induced striatal DA changes. These results provide preliminary evidence that low striatal DA function in METH abusers is associated with a greater likelihood of relapse during treatment. Detection of the extent of DA dysfunction may be helpful in predicting therapeutic outcomes.

  4. Increasing Physical Activity Decreases Hepatic Fat and Metabolic Risk Factors.

    Science.gov (United States)

    Alderete, Tanya L; Gyllenhammer, Lauren E; Byrd-Williams, Courtney E; Spruijt-Metz, Donna; Goran, Michael I; Davis, Jaimie N

    2012-04-01

    This study assessed the changes in time spent in moderate to vigorous physical activity (MVPA) on fat depots, insulin action, and inflammation. Longitudinal data were generated from 66 Hispanic adolescents (15.6±1.1 yr; BMI percentile 97.1±3.0) who participated in a 16-wk nutrition or nutrition+exercise intervention. There were no effects of the intervention on PA, but there were inter-individual changes in PA. For purposes of this analysis, all intervention groups were combined to assess how changes in PA during 16 wk affected changes in adiposity, insulin action, and markers of inflammation. MVPA was assessed by 7-day accelerometry, total body fat via DXA, liver fat by MRI, and insulin, glucose and HOMA-IR via a fasting blood draw. A repeated measures ANCOVA was used to assess the effect of MVPA on fat depots, insulin action, and inflammatory markers. Sixty-two percent of participants increased MVPA (mean increase, 19.7±16.5 min/day) and 38% decreased MVPA (mean decrease, 10.7±10.1 min/day). Those who increased MVPA by as little as 20 min per day over 16 wk, compared to those who decreased MVPA, had significant reductions in liver fat (-13% vs. +3%; P=0.01), leptin levels (-18% vs. +4%; P=0.02), and fasting insulin (-23% vs. +5%; P=0.05). These findings indicate that a modest increase in MVPA can improve metabolic health in sedentary overweight Hispanic adolescents.

  5. Intracellular water motion decreases in apoptotic macrophages after caspase activation.

    Science.gov (United States)

    Hortelano, S; García-Martín, M L; Cerdán, S; Castrillo, A; Alvarez, A M; Boscá, L

    2001-10-01

    Triggering of the macrophage cell line RAW 264.7 with lipopolysaccharide and interferon-gamma promoted apoptosis that was prevented by inhibitors of type 2 nitric oxide synthase or caspase. Using (1)H NMR analysis, we have investigated the changes of the intracellular transverse relaxation time (T(2)) and apparent diffusion coefficient (ADC) as parameters reflecting the rotational and translational motions of water in apoptotic macrophages. T(2) values decreased significantly from 287 to 182 ms in cells treated for 18 h with NO-donors. These changes of T(2) were prevented by caspase inhibitors and were not due to mitochondrial depolarization or microtubule depolymerization. The decrease of the intracellular values of T(2) and ADC in apoptotic macrophages was observed after caspase activation, but preceded phosphatidylserine exposure and nucleosomal DNA cleavage. The changes of water motion were accompanied by an enhancement of the hydrophobic properties of the intracellular milieu, as detected by fluorescent probes. These results indicate the occurrence of an alteration in the physicochemical properties of intracellular water during the course of apoptosis.

  6. Telomerase inhibitor Imetelstat (GRN163L limits the lifespan of human pancreatic cancer cells.

    Directory of Open Access Journals (Sweden)

    Katrina M Burchett

    Full Text Available Telomerase is required for the unlimited lifespan of cancer cells. The vast majority of pancreatic adenocarcinomas overexpress telomerase activity and blocking telomerase could limit their lifespan. GRN163L (Imetelstat is a lipid-conjugated N3'→P5' thio-phosphoramidate oligonucleotide that blocks the template region of telomerase. The aim of this study was to define the effects of long-term GRN163L exposure on the maintenance of telomeres and lifespan of pancreatic cancer cells. Telomere size, telomerase activity, and telomerase inhibition response to GRN163L were measured in a panel of 10 pancreatic cancer cell lines. The cell lines exhibited large differences in levels of telomerase activity (46-fold variation, but most lines had very short telomeres (2-3 kb in size. GRN163L inhibited telomerase in all 10 pancreatic cancer cell lines, with IC50 ranging from 50 nM to 200 nM. Continuous GRN163L exposure of CAPAN1 (IC50 = 75 nM and CD18 cells (IC50 = 204 nM resulted in an initial rapid shortening of the telomeres followed by the maintenance of extremely short but stable telomeres. Continuous exposure to the drug eventually led to crisis and to a complete loss of viability after 47 (CAPAN1 and 69 (CD18 doublings. Crisis In these cells was accompanied by activation of a DNA damage response (γ-H2AX and evidence of both senescence (SA-β-galactosidase activity and apoptosis (sub-G1 DNA content, PARP cleavage. Removal of the drug after long-term GRN163L exposure led to a reactivation of telomerase and re-elongation of telomeres in the third week of cultivation without GRN163L. These findings show that the lifespan of pancreatic cancer cells can be limited by continuous telomerase inhibition. These results should facilitate the design of future clinical trials of GRN163L in patients with pancreatic cancer.

  7. Telomerase inhibitor Imetelstat (GRN163L) limits the lifespan of human pancreatic cancer cells.

    Science.gov (United States)

    Burchett, Katrina M; Yan, Ying; Ouellette, Michel M

    2014-01-01

    Telomerase is required for the unlimited lifespan of cancer cells. The vast majority of pancreatic adenocarcinomas overexpress telomerase activity and blocking telomerase could limit their lifespan. GRN163L (Imetelstat) is a lipid-conjugated N3'→P5' thio-phosphoramidate oligonucleotide that blocks the template region of telomerase. The aim of this study was to define the effects of long-term GRN163L exposure on the maintenance of telomeres and lifespan of pancreatic cancer cells. Telomere size, telomerase activity, and telomerase inhibition response to GRN163L were measured in a panel of 10 pancreatic cancer cell lines. The cell lines exhibited large differences in levels of telomerase activity (46-fold variation), but most lines had very short telomeres (2-3 kb in size). GRN163L inhibited telomerase in all 10 pancreatic cancer cell lines, with IC50 ranging from 50 nM to 200 nM. Continuous GRN163L exposure of CAPAN1 (IC50 = 75 nM) and CD18 cells (IC50 = 204 nM) resulted in an initial rapid shortening of the telomeres followed by the maintenance of extremely short but stable telomeres. Continuous exposure to the drug eventually led to crisis and to a complete loss of viability after 47 (CAPAN1) and 69 (CD18) doublings. Crisis In these cells was accompanied by activation of a DNA damage response (γ-H2AX) and evidence of both senescence (SA-β-galactosidase activity) and apoptosis (sub-G1 DNA content, PARP cleavage). Removal of the drug after long-term GRN163L exposure led to a reactivation of telomerase and re-elongation of telomeres in the third week of cultivation without GRN163L. These findings show that the lifespan of pancreatic cancer cells can be limited by continuous telomerase inhibition. These results should facilitate the design of future clinical trials of GRN163L in patients with pancreatic cancer.

  8. Telomerase Inhibitor Imetelstat in Patients with Essential Thrombocythemia.

    OpenAIRE

    Baerlocher, Gabriela M.; Oppliger Leibundgut, Elisabeth; Ottmann, Oliver G; Spitzer, Gary; Odenike, Olatoyosi; McDevitt, Michael A.; Röth, Alexander; Daskalakis, Michael; Burington, Bart; Stuart, Monic; Snyder, David S.

    2015-01-01

    BACKGROUND Imetelstat, a 13-mer oligonucleotide that is covalently modified with lipid extensions, competitively inhibits telomerase enzymatic activity. It has been shown to inhibit megakaryocytic proliferation in vitro in cells obtained from patients with essential thrombocythemia. In this phase 2 study, we investigated whether imetelstat could elicit hematologic and molecular responses in patients with essential thrombocythemia who had not had a response to or who had had unacceptable s...

  9. Human Telomerase Reverse Transcriptase (hTERT) Transcription Requires Sp1/Sp3 Binding to the Promoter and a Permissive Chromatin Environment.

    Science.gov (United States)

    Cheng, De; Zhao, Yuanjun; Wang, Shuwen; Jia, Wenwen; Kang, Jiuhong; Zhu, Jiyue

    2015-12-11

    The transcription of human telomerase gene hTERT is regulated by transcription factors (TFs), including Sp1 family proteins, and its chromatin environment. To understand its regulation in a relevant chromatin context, we employed bacterial artificial chromosome reporters containing 160 kb of human genomic sequence containing the hTERT gene. Upon chromosomal integration, the bacterial artificial chromosomes recapitulated endogenous hTERT expression, contrary to transient reporters. Sp1/Sp3 expression did not correlate with hTERT promoter activity, and these TFs bound to the hTERT promoters in both telomerase-positive and telomerase-negative cells. Mutation of the proximal GC-box resulted in a dramatic decrease of hTERT promoter activity, and mutations of all five GC-boxes eliminated its transcriptional activity. Neither mutations of GC-boxes nor knockdown of endogenous Sp1 impacted promoter binding by other TFs, including E-box-binding proteins, and histone acetylation and trimethylation of histone H3K9 at the hTERT promoter in telomerase-positive and -negative cells. The result indicated that promoter binding by Sp1/Sp3 was essential, but not a limiting step, for hTERT transcription. hTERT transcription required a permissive chromatin environment. Importantly, our data also revealed different functions of GC-boxes and E-boxes in hTERT regulation; although GC-boxes were essential for promoter activity, factors bound to the E-boxes functioned to de-repress hTERT promoter.

  10. Evaluation of telomerase expression in chronic periodontitis

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    Balaji T

    2010-01-01

    Full Text Available 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 reverse transcriptase polymerase chain reaction. Materials and Methods : Gingival biopsies were obtained from eight healthy subjects and eight chronic periodontitis patients. Reverse transcriptase polymerase chain reaction (RTPCR was carried out to evaluate telomerase gene expression in the samples. Results : None of the healthy gingival tissue samples expressed the telomerase gene while all the chronic periodontitis samples expressed it. The severe chronic periodontitis samples expressed the gene more intensely than the moderate chronic periodontitis samples. Conclusion : Various mechanisms have been explained to account for telomerase elevation in chronic periodontitis .This study helps us understand the role of telomerase in the pathogenesis of periodontal disease. It could be concluded that telomerase could be used as a marker to assess the severity of inflammation in chronic periodontitis.

  11. Examination of Telomerase Expression with Immuno-Hystochemistry Techniques on Some of Cancer Cells

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    Endang Purwaningsih

    2016-04-01

    Full Text Available Objective: Cancer is a disease that gets serious attention in the medical world. This is due to the ever increasing number of patients and there has been no effective way to treat. Cancer cells have telomerase activity is relatively high compared to normal cells, so the cancer cells have the ability to continue to proliferate. Cancer cells undergo uncontrolled mitosis and have high telomerase activity compared to cells normal. Telomerase is an enzyme responsible for telomere length, a segment of DNA that is the tip of chromosomes in eukaryotic cells. Telomeres are associated with the process of aging and carcinogenesis. The purpose of this study was to determine the expression of telomerase in some cells such as breast cancer, cervical cancer, and lung cancer. Methods: The research method is experimental studies in several cancer cell cultures in the form of cell line. Cancer cells used were: HeLa (cervical cancer, MCF7 and T47D (breast cancer, WiDr (lung cancer, and Raji (lymphoma with culture medium RPMI, DMEM, and M199. Vero cells is used (fibroblast cells as a control (normal cells. Expression of telomerase enzyme was measured by the Immunohystochemistry (IHC method. Results: The results showed that the cancer cells have activity/higher telomerase expression were highly significant (p<0.01 compared to normal cells (Vero cells. Similarly, the expression of telomerase in HeLa versus WiDr, WiDr versus T47D, T47D versus Raji, and Raji versus MCF7 also showed highly significant differences (p<0.01. Telomerase expression between cancer cells that showed significant difference (HeLa cells versus Raji cells; HeLa cells versus MCF7 cell; T47D cells versus MCF7 cells (p<0.05. No significant difference was found in the group of HeLa cells versus T47D, WiDr versus Raji cells, and WiDr versus MCF7. Conclusions: It was concluded, that the cancer cells have telomerase expression of specific and different from each other, depending on the type of cell. T47D

  12. Inhibition of human telomerase enhances the effect of chemotherapeutic agents in lung cancer cells.

    Science.gov (United States)

    Misawa, Masafumi; Tauchi, Tetsuzo; Sashida, Goro; Nakajima, Akihiro; Abe, Kenji; Ohyashiki, Junko H; Ohyashiki, Kazuma

    2002-11-01

    Telomerase is a ribonucleoprotein enzyme that maintains protective structures at the ends of eukaryotic chromosomes. Earlier studies have reported that the presence of telomerase activity in tumors of patients with non-small cell lung cancer patients correlates with a high proliferation rate and advanced pathological stage. Thus, the modification of telomerase activity may be a potential therapeutic modality for the treatment of lung and other cancers. We introduced vectors encoding dominant negative (DN)-hTERT, or wild-type (WT)-hTERT, or a control vector expressing only a drug-resistance marker, into the A549 lung cancer cell line, and assessed the biological effect of telomerase inhibition on cellular immortality. Ectopic expression of DN-hTERT resulted in complete inhibition of telomerase activity and reduction of telomere length. The entire population of telomerase-inhibited A549 cells exhibited cytoplasmic blebbling and chromatin condensation, which are features of apoptosis. In contrast, A549 cells expressing wild-type hTERT, which differs from the mutants by only two amino acids, exhibited normal morphology. Evidence for apoptosis in the telomerase-inhibited cells was provided by flow cytometric analysis with APO2.7 monoclonal antibody. We also observed enhanced induction of apoptosis by chemotherapeutic reagents, including cisplatin, docetaxel and etoposide, in DN-hTERT-expressing A549 cells, as compared with WT-hTERT-expressing cells. These results demonstrate that disruption of telomere maintenance limits the cellular lifespan of lung cancer cells, and show that the combined use of chemotherapeutic agents and telomere maintenance inhibition may be effective in the treatment of patients with non-small cell lung cancer.

  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; Rosada, Cecilia; 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......, 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 functions....

  14. Collapse of telomere homeostasis in hematopoietic cells caused by heterozygous mutations in telomerase genes.

    Directory of Open Access Journals (Sweden)

    Geraldine Aubert

    Full Text Available 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 healthy individuals and 60 individuals with reduced telomerase activity. Healthy individuals showed a broad range in average telomere length in granulocytes and lymphocytes at any given age. The average telomere length declined with age at a rate that differed between age-specific breakpoints and between cell types. Gender differences between leukocyte telomere lengths were observed for all cell subsets studied; interestingly, this trend could already be detected at birth. Heterozygous carriers for mutations in either the telomerase reverse transcriptase (hTERT or the telomerase RNA template (hTERC gene displayed striking and comparable telomere length deficits. Further, non-carrier relatives of such heterozygous individuals had somewhat shorter leukocyte telomere lengths than expected; this difference was most profound for granulocytes. Failure to maintain telomere homeostasis as a result of partial telomerase deficiency is thought to trigger cell senescence or cell death, eventually causing tissue failure syndromes. Our data are consistent with these statements and suggest that the likelihood of similar processes occurring in normal individuals increases with age. Our work highlights the essential role of telomerase in the hematopoietic system and supports the notion that telomerase levels in hematopoietic cells, while limiting and unable to prevent overall telomere shortening, are nevertheless crucial to maintain telomere homeostasis with age.

  15. Telomerase contributes to fludarabine resistance in primary human leukemic lymphocytes.

    Science.gov (United States)

    Shawi, May; Chu, Tsz Wai; Martinez-Marignac, Veronica; Yu, Y; Gryaznov, Sergei M; Johnston, James B; Lees-Miller, Susan P; Assouline, Sarit E; Autexier, Chantal; Aloyz, Raquel

    2013-01-01

    We report that Imetelstat, a telomerase inhibitor that binds to the RNA component of telomerase (hTR), can sensitize primary CLL lymphocytes to fludarabine in vitro. This effect was observed in lymphocytes from clinically resistant cases and with cytogenetic abnormalities associated with bad prognosis. Imetelstat mediated-sensitization to fludarabine was not associated with telomerase activity, but with the basal expression of Ku80. Since both Imetelstat and Ku80 bind hTR, we assessed 1) if Ku80 and Imetelstat alter each other's binding to hTR in vitro and 2) the effect of an oligonucleotide complementary to the Ku binding site in hTR (Ku oligo) on the survival of primary CLL lymphocytes exposed to fludarabine. We show that Imetelstat interferes with the binding of Ku70/80 (Ku) to hTR and that the Ku oligo can sensitize CLL lymphocytes to FLU. Our results suggest that Ku binding to hTR may contribute to fludarabine resistance in CLL lmphocytes. This is the first report highlighting the potentially broad effectiveness of Imetelstat in CLL, and the potential biological and clinical implications of a functional interaction between Ku and hTR in primary human cancer cells.

  16. Telomerase contributes to fludarabine resistance in primary human leukemic lymphocytes.

    Directory of Open Access Journals (Sweden)

    May Shawi

    Full Text Available We report that Imetelstat, a telomerase inhibitor that binds to the RNA component of telomerase (hTR, can sensitize primary CLL lymphocytes to fludarabine in vitro. This effect was observed in lymphocytes from clinically resistant cases and with cytogenetic abnormalities associated with bad prognosis. Imetelstat mediated-sensitization to fludarabine was not associated with telomerase activity, but with the basal expression of Ku80. Since both Imetelstat and Ku80 bind hTR, we assessed 1 if Ku80 and Imetelstat alter each other's binding to hTR in vitro and 2 the effect of an oligonucleotide complementary to the Ku binding site in hTR (Ku oligo on the survival of primary CLL lymphocytes exposed to fludarabine. We show that Imetelstat interferes with the binding of Ku70/80 (Ku to hTR and that the Ku oligo can sensitize CLL lymphocytes to FLU. Our results suggest that Ku binding to hTR may contribute to fludarabine resistance in CLL lmphocytes. This is the first report highlighting the potentially broad effectiveness of Imetelstat in CLL, and the potential biological and clinical implications of a functional interaction between Ku and hTR in primary human cancer cells.

  17. Telomerase Regulation from Beginning to the End

    Directory of Open Access Journals (Sweden)

    Deanna Elise MacNeil

    2016-09-01

    Full Text Available The vast body of literature regarding human telomere maintenance is a true testament to the importance of understanding telomere regulation in both normal and diseased states. In this review, our goal was simple: tell the telomerase story from the biogenesis of its parts to its maturity as a complex and function at its site of action, emphasizing new developments and how they contribute to the foundational knowledge of telomerase and telomere biology.

  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. Effect of telomerase inhibition on preclinical models of malignant rhabdoid tumor.

    Science.gov (United States)

    Hu, Yafang; Bobb, Daniel; Lu, Yunbiao; He, Jianping; Dome, Jeffrey S

    2014-09-01

    Novel treatment approaches are desperately needed for malignant rhabdoid tumor (MRT). Telomerase is an attractive therapeutic target because it is specific to cancer and critical for cancer cell immortality. We evaluated the effect of the telomerase inhibitor imetelstat in preclinical models of MRT. Three MRT cell lines, BT-12, G401, and RT-peri, were treated with the telomerase inhibitor imetelstat. The effects of imetelstat on telomere length, DNA damage response, and cell proliferation were assessed. The efficacy of imetelstat in vivo was evaluated in subcutaneous xenografts derived from each of the cell lines. Treatment with imetelstat resulted in inhibition of telomerase activity, marked telomere shortening, and activation of the DNA damage response pathway, as measured by formation of γ-H2AX nuclear foci, phosphorylation of ATM, and phosphorylation of TP53. Imetelstat-treated G401 cells underwent complete growth arrest after 16 passages. The other two cell lines exhibited growth inhibition. Imetelstat resulted in 40-50% growth inhibition compared to placebo-treated controls in all three xenograft models. The activity of imetelstat as a single agent suggests that further studies of telomerase inhibitors in combination with other agents may be warranted.

  20. 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

  1. 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

  2. A spectrum of severe familial liver disorders associate with telomerase mutations.

    Directory of Open Access Journals (Sweden)

    Rodrigo T Calado

    Full Text Available BACKGROUND: Telomerase is an enzyme specialized in maintaining telomere lengths in highly proliferative cells. Loss-of-function mutations cause critical telomere shortening and are associated with the bone marrow failure syndromes dyskeratosis congenita and aplastic anemia and with idiopathic pulmonary fibrosis. Here, we sought to determine the spectrum of clinical manifestations associated with telomerase loss-of-function mutations. METHODOLOGY/PRINCIPAL FINDINGS: Sixty-nine individuals from five unrelated families with a variety of hematologic, hepatic, and autoimmune disorders were screened for telomerase complex gene mutations; leukocyte telomere length was measured by flow fluorescence in situ hybridization in mutation carriers and some non-carriers; the effects of the identified mutations on telomerase activity were determined; and genetic and clinical data were correlated. In six generations of a large family, a loss-of-function mutation in the telomerase enzyme gene TERT associated with severe telomere shortening and a range of hematologic manifestations, from macrocytosis to acute myeloid leukemia, with severe liver diseases marked by fibrosis and inflammation, and one case of idiopathic pulmonary fibrosis but not with autoimmune disorders. Additionally, we identified four unrelated families in which loss-of-function TERC or TERT gene mutations tracked with marrow failure, pulmonary fibrosis, and a spectrum of liver disorders. CONCLUSIONS/SIGNIFICANCE: These results indicate that heterozygous telomerase loss-of-function mutations associate with but are not determinant of a large spectrum of hematologic and liver abnormalities, with the latter sometimes occurring in the absence of marrow failure. Our findings, along with the link between pulmonary fibrosis and telomerase mutations, also suggest a common pathogenic mechanism for fibrotic diseases in which defective telomere repair plays important role.

  3. 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.

  4. Prognostic significance of telomerase-associated parameters in glioblastoma: effect of patient age.

    Science.gov (United States)

    Lötsch, Daniela; Ghanim, Bahil; Laaber, Magdalena; Wurm, Gabriele; Weis, Serge; Lenz, Stefan; Webersinke, Gerald; Pichler, Josef; Berger, Walter; Spiegl-Kreinecker, Sabine

    2013-04-01

    Glioblastoma multiforme (GBM) is a heterogeneous, highly aggressive primary brain tumor with strongly variable patient survival. Because reliable prognostic biomarkers are lacking, we investigated the relation between telomerase-associated parameters and the disease course. Telomerase-associated parameters were determined in 100 GBM tissues and associated with clinical characteristics and overall survival. Expressions of telomere length, telomerase activity (TA), and human telomerase reverse transcriptase (hTERT) were analyzed by quantitative PCR, telomeric repeat amplification protocol assay, and reverse transcriptase-PCR, respectively. Mutation status of isocitrate dehydrogenase (IDH)1 was determined by direct sequencing, and O(6)-methylguanine DNA methyltransferase (MGMT) promoter methylation by methylation-specific PCR. Of 100 GBM tissues, 61 were positive for both hTERT mRNA and TA, with a highly significant correlation between both parameters (linear regression, P 60 y at diagnosis, P 60 y, both ns). Telomerase activation is not an independent prognostic parameter in GBM but predicts aggressive tumor behavior solely in a younger patient cohort.

  5. Telomerase inhibition and telomere loss in BEL-7404 human hepatoma cells treated with doxorubicin

    Institute of Scientific and Technical Information of China (English)

    Ru-Gang Zhang; Li-Xia Guo; Xing-Wang Wang; Hong Xie

    2002-01-01

    AIM: To study the effects of doxorubicin on telomeraseactivity and telomere length in hepatocellular carcinoma.METHODS: Telomerase activity was assayed with a non-radioisotopic quantitative telomerase repeat amplificationprotocal-based method. The effect of doxorubicin (DOX) onthe growth of BEL-7404 human hepatoma cells wasdetermined by microculture tetrazolium assay. Meantelomere length (terminal restriction fragment) was detectedby Southern blot method. The expression of telomerasesubunits genes was investigated by RT-PCR. Cell apoptosisand cell cycle distribution were evaluated by flow cytometry.RESULTS: Telomerase activity was inhibited in a dose andtime-dependent manner in BEL-7404 human hepatoma cellstreated with DOX for 24, 48 or 72 h in concentrations from0.156 to 2.5 μM which was crrelated with the inhibition ofcell growth. No changes were found in the mRNA expressionof three telomerase subunits (hTERT, hTR and TP1) afterdrug exposure for 72 h with indicated concentrations. Thecells treated with DOX showed shortened mean telomerelength and accumulated at the G2/M phase. However, therewas almost no effects on cell apoptosis by DOX.CONCLUSION: The telomerase inhibition and the telomereshortening by DOX may contribute to its efficiency in thetreatment in hepatocellular carcinoma.

  6. The telomerase inhibitor imetelstat depletes cancer stem cells in breast and pancreatic cancer cell lines.

    Science.gov (United States)

    Joseph, Immanual; Tressler, Robert; Bassett, Ekaterina; Harley, Calvin; Buseman, Christen M; Pattamatta, Preeti; Wright, Woodring E; Shay, Jerry W; Go, Ning F

    2010-11-15

    Cancer stem cells (CSC) are rare drug-resistant cancer cell subsets proposed to be responsible for the maintenance and recurrence of cancer and metastasis. Telomerase is constitutively active in both bulk tumor cell and CSC populations but has only limited expression in normal tissues. Thus, inhibition of telomerase has been shown to be a viable approach in controlling cancer growth in nonclinical studies and is currently in phase II clinical trials. In this study, we investigated the effects of imetelstat (GRN163L), a potent telomerase inhibitor, on both the bulk cancer cells and putative CSCs. When breast and pancreatic cancer cell lines were treated with imetelstat in vitro, telomerase activity in the bulk tumor cells and CSC subpopulations were inhibited. Additionally, imetelstat treatment reduced the CSC fractions present in the breast and pancreatic cell lines. In vitro treatment with imetelstat, but not control oligonucleotides, also reduced the proliferation and self-renewal potential of MCF7 mammospheres and resulted in cell death after imetelstat, suggesting a mechanism of action independent of telomere shortening for the effects of imetelstat on the CSC subpopulations. Our results suggest that imetelstat-mediated depletion of CSCs may offer an alternative mechanism by which telomerase inhibition may be exploited for cancer therapy.

  7. Physically active lifestyle does not decrease the risk of fattening.

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    Klaas R Westerterp

    Full Text Available BACKGROUND: Increasing age is associated with declining physical activity and a gain in fat mass. The objective was to observe the consequence of the age-associated reduction in physical activity for the maintenance of energy balance as reflected in the fat store of the body. METHODOLOGY/PRINCIPAL FINDINGS: Young adults were observed over an average time interval of more than 10 years. Physical activity was measured over two-week periods with doubly labeled water and doubly labeled water validated triaxial accelerometers, and body fat gain was measured with isotope dilution. There was a significant association between the change in physical activity and the change in body fat, where a high initial activity level was predictive for a higher fat gain. CONCLUSION/SIGNIFICANCE: The change from a physically active to a more sedentary routine does not induce an equivalent reduction of energy intake and requires cognitive restriction to maintain energy balance.

  8. Decreased replication origin activity in temporal transition regions.

    Science.gov (United States)

    Guan, Zeqiang; Hughes, Christina M; Kosiyatrakul, Settapong; Norio, Paolo; Sen, Ranjan; Fiering, Steven; Allis, C David; Bouhassira, Eric E; Schildkraut, Carl L

    2009-11-30

    In the mammalian genome, early- and late-replicating domains are often separated by temporal transition regions (TTRs) with novel properties and unknown functions. We identified a TTR in the mouse immunoglobulin heavy chain (Igh) locus, which contains replication origins that are silent in embryonic stem cells but activated during B cell development. To investigate which factors contribute to origin activation during B cell development, we systematically modified the genetic and epigenetic status of the endogenous Igh TTR and used a single-molecule approach to analyze DNA replication. Introduction of a transcription unit into the Igh TTR, activation of gene transcription, and enhancement of local histone modifications characteristic of active chromatin did not lead to origin activation. Moreover, very few replication initiation events were observed when two ectopic replication origin sequences were inserted into the TTR. These findings indicate that the Igh TTR represents a repressive compartment that inhibits replication initiation, thus maintaining the boundaries between early and late replication domains.

  9. Decreased Chitotriosidase Activity and Levels in Familial Mediterranean Fever.

    Science.gov (United States)

    Doğan, Halef Okan; Omma, Ahmet; Turhan, Turan; Boğdaycıoğlu, Nihal; Karaaslan, Yaşar; Yavuz, Hayrettin; Demirpençe, Özlem; Aydın, Hüseyin; Bakır, Sevtap

    2016-12-01

    Different studies have demonstrated changes in chitotriosidase (ChT) activity and concentrations in multiple diseases. However, changes in ChT activity and concentrations have not been concurrently evaluated in patients with Familial Mediterranean Fever (FMF). In this study, we analyzed the changes in serum ChT activity and concentrations in patients with FMF. The study included a total of 80 patients with FMF and 80 healthy controls. ChT enzyme activity and concentrations were measured and then compared between the groups. ChT activity was measured by using fluorometric ELISA and ChT concentrations were measured by using colorimetric ELISA methods. The median ChT activity was 10.00 (6.00-15.00) nmol/mL/hr in the patients and 14.00 (6.25-20.75) nmol/mL/hr in the controls. There was a statistically significant difference in the ChT activity between the controls and patients (P = 0.027). The median ChT concentrations were 65.40 (46.20-84.92) pg/mL and 125.00 (75.72-143.95) pg/mL in the patients and controls, respectively (P < 0.001), which were expressed as median percentiles (25th-75th). Additionally, we found no correlation between C-reactive protein and ChT activity (P = 0.978, r = 0.003) and concentrations (P = 0.446, r = -0.87). Serum ChT enzyme activity and concentrations may not be considered as a biomarker in FMF patients taking colchicine. New studies are needed to evaluate the changes of enzyme activity and concentration in colchicine-negative patients.

  10. Novel Efficient Cell-Penetrating, Peptide-Mediated Strategy for Enhancing Telomerase Inhibitor Oligonucleotides.

    Science.gov (United States)

    Muñoz-Alarcón, Andrés; Eriksson, Jonas; Langel, Ülo

    2015-12-01

    At present, there are several therapeutic approaches for targeting telomerase in tumors. One in particular, currently undergoing clinical trials, is based on synthetic lipid-modified oligonucleotide antagonists aimed at inhibiting the ribonucleoprotein subunit of human telomerase. However, while enabling efficient uptake, the lipid modifications reduce the potency of the therapeutic oligonucleotides compared to nonmodified oligonucleotides. Moreover, lipid modification may increase oligonucleotide accumulation in the liver causing undesirable hepatotoxicity. Noncovalent complexation strategies for cell-penetrating peptide (CPP)-mediated delivery present an option to circumvent the need for potency-reducing modifications, while allowing for a highly efficient uptake, and could significantly improve the efficiency of telomerase-targeting cancer therapeutics. Delivery of a nonlipidated locked nucleic acid/2'-O-methyl mixmer significantly inhibits the telomerase activity in treated HeLa cells. The inhibitory effect was further improved through addition of a CPP. Furthermore, calculated IC50-values for the oligonucleotide delivered by CPPs into HeLa cells are more than 20 times lower than telomerase inhibitor Imetelstat, currently undergoing clinical trials. These results emphasize the potential of CPP-mediated delivery of future pharmaceuticals and provide means by which to enhance an already promising therapeutic strategy for cancer treatment.

  11. The Ctf18RFC clamp loader is essential for telomere stability in telomerase-negative and mre11 mutant alleles.

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    Honghai Gao

    Full Text Available The function of the replication clamp loaders in the semi-conservative telomere replication and their relationship to telomerase- and recombination mechanisms of telomere addition remains ambiguous. We have investigated the variant clamp loader Ctf18 RFC (Replication Factor C. To understand the role of Ctf18 at the telomere, we first investigated genetic interactions after loss of Ctf18 and TLC1 (the yeast telomerase RNA. We find that the tlc1Δ ctf18Δ double mutant confers a rapid >1000-fold decrease in viability. The rate of loss was similar to the kinetics of cell death in rad52Δ tlc1Δ cells. However, the Ctf18 pathway is distinct from Rad52, required for the repair of DSBs, as demonstrated by the synthetic lethality of rad52▵ tlc1Δ ctf18Δ triple mutants. These data suggest that each mutant elicits non-redundant defects acting on the same substrate. Second, interactions of the yeast hyper-recombinational mutant, mre11A470T, with ctf18▵ confer a synergistic cold sensitivity. The phenotype of these double mutants ultimately results in telomere loss and the generation of recombinational survivors. We observed a similar synergism between single mutants that led to hypersensitivity to the DNA alkylating agent, methane methyl sulphonate (MMS, the replication fork inhibitor hydroxyurea (HU, and to a failure to separate telomeres of sister chromatids. Hence, ctf18Δ and mre11A470T act in different pathways on telomere substrates for multiple phenotypes. The mre11A470T cells also displayed a DNA damage response (DDR at 15°C but not at 30°C while ctf18Δ mutants conferred a constitutive DDR activity. Both the 15°C DDR pattern and growth rate were reversible at 30°C and displayed telomerase activity in vivo. We hypothesize that Ctf18 confers protection against stalling and/or breaks at the replication fork in cells that either lack, or are compromised for, telomerase activity. This Ctf18-based function is likely to contribute another level

  12. Gastrointestinal stromal tumors - quantitative detection of the Ki-67, TPX2, TOP2A, and hTERT telomerase subunit mRNA levels to determine proliferation activity and a potential for aggressive biological behavior.

    Science.gov (United States)

    Kalfusova, A; Hilska, I; Krskova, L; Kalinova, M; Linke, Z; Kodet, R

    2016-01-01

    Gastrointestinal stromal tumors (GISTs) have an unpredictable biological potential ranging from benign to malignant. Molecular markers involved in the mechanisms of proliferation and cellular senescence may provide additional information about biological behavior of the tumor. The aim of the present study was to investigate Ki-67, TPX2, TOP2A and hTERT mRNA expression levels in specimens from patients with GISTs to define relationships between proliferation activity and biological potential and progression of the disease. We measured Ki-67, TPX2, TOP2A and hTERT mRNA levels using quantitative real-time reverse transcription PCR (RQ RT PCR). The highest Ki-67, TPX2, TOP2A and hTERT mRNA expression levels were found in the highly proliferative BLs (18 specimens), in comparison with GISTs (137 specimens) and LMSs (9 specimens). Patients with GISTs and adequate information about mitotic activity, tumor size and anatomical site (84 specimens) were divided into two groups - GISTs with benign (29 patients) and with malignant (55 patients) potential. We observed association between higher Ki-67, TPX2 and hTERT mRNA levels and the GISTs with malignant potential. Univariate analysis (57 patients with available follow-up information) of survival (Kaplan Meier curves method) revealed a correlation between higher levels of TPX2, Ki-67 and hTERT markers and shorter event-free survival (EFS) or poorer overall survival (OS). The results demonstrate the importance of quantitative assessment of the proliferation activity in GISTs. Proliferation markers of Ki-67, TPX2, TOP2A and hTERT are suitable markers for detection the proliferation activity and telomerase activity of these tumors. Furthermore, the assessment of TPX2, Ki-67 and hTERT expression levels is appropriate for determination of malignant potential of GISTs.

  13. Decreased Heme Oxygenase Activity in Patients with Alzheimer's Disease

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    Berkay Cataloglu

    2013-04-01

    Full Text Available Alzheimer's disease is a neurodegenerative disorder characterized with progressive im-pairment of cognitive functions. Heme oxygenase is an enzyme that degrades the heme molecule resulting in equimolar amounts of the carbon monoxide, ferrous iron, and bili-verdin. Up to now, heme oxygenase activity and its metabolic effects in Alzheimer's dis-ease have been investigated in so many studies; most of them were performed in post-mortem brain tissues of Alzheimer's disease patients or in animal models. Therefore, we aimed to investigate heme oxygenase activity in leukocytes of Alzheimer's disease pa-tients as a peripheral sample. Mean heme oxygenase activity was significantly lower in patients with Alzheimer's disease (0.53 +/- 0.32 nmol/h/mg protein compared to control sucjects (1.19 +/- 0.84 nmol/h/mg protein (p= 0.001. We think that reduction in leukocyte heme oxygenase activity may limit disease progression through preserving peripheral mitochondrial function by reducing the formation of free iron and carbon monoxide. [Dis Mol Med 2013; 1(2.000: 31-34

  14. The telomerase reverse transcriptase subunit from the dimorphic fungus Ustilago maydis.

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    Dolores Bautista-España

    Full Text Available In this study, we investigated the reverse transcriptase subunit of telomerase in the dimorphic fungus Ustilago maydis. This protein (Trt1 contains 1371 amino acids and all of the characteristic TERT motifs. Mutants created by disrupting trt1 had senescent traits, such as delayed growth, low replicative potential, and reduced survival, that were reminiscent of the traits observed in est2 budding yeast mutants. Telomerase activity was observed in wild-type fungus sporidia but not those of the disruption mutant. The introduction of a self-replicating plasmid expressing Trt1 into the mutant strain restored growth proficiency and replicative potential. Analyses of trt1 crosses in planta suggested that Trt1 is necessary for teliospore formation in homozygous disrupted diploids and that telomerase is haploinsufficient in heterozygous diploids. Additionally, terminal restriction fragment analysis in the progeny hinted at alternative survival mechanisms similar to those of budding yeast.

  15. The telomerase reverse transcriptase subunit from the dimorphic fungus Ustilago maydis.

    Science.gov (United States)

    Bautista-España, Dolores; Anastacio-Marcelino, Estela; Horta-Valerdi, Guillermo; Celestino-Montes, Antonio; Kojic, Milorad; Negrete-Abascal, Erasmo; Reyes-Cervantes, Hortensia; Vázquez-Cruz, Candelario; Guzmán, Plinio; Sánchez-Alonso, Patricia

    2014-01-01

    In this study, we investigated the reverse transcriptase subunit of telomerase in the dimorphic fungus Ustilago maydis. This protein (Trt1) contains 1371 amino acids and all of the characteristic TERT motifs. Mutants created by disrupting trt1 had senescent traits, such as delayed growth, low replicative potential, and reduced survival, that were reminiscent of the traits observed in est2 budding yeast mutants. Telomerase activity was observed in wild-type fungus sporidia but not those of the disruption mutant. The introduction of a self-replicating plasmid expressing Trt1 into the mutant strain restored growth proficiency and replicative potential. Analyses of trt1 crosses in planta suggested that Trt1 is necessary for teliospore formation in homozygous disrupted diploids and that telomerase is haploinsufficient in heterozygous diploids. Additionally, terminal restriction fragment analysis in the progeny hinted at alternative survival mechanisms similar to those of budding yeast.

  16. Decrease in T Cell Activation and Calcium Flux during Clinorotation

    Science.gov (United States)

    Sams, Clarence; Holtzclaw, J. David

    2006-01-01

    We investigated the effect of altered gravitational environments on T cell activation. We isolated human, naive T cells (CD3+CD14-CD19-CD16-CD56-CD25-CD69-CD45RA-) following IRB approved protocols. These purified T cells were then incubated with 6 mm polystyrene beads coated with OKT3 (Ortho Biotech, Raritan, NJ) and antiCD28 (Becton Dickinson (BD), San Jose, CA) at 37 C for 24 hours. Antibodies were at a 1:1 ratio and the bead-to-cell ratio was 2:1. Four incubation conditions existed: 1) static or "1g"; 2) centrifugation at 10 relative centrifugal force (RCF) or "10g"; 3) clinorotation at 25 RPM (functional weightlessness or "0g"); and 4) clinorotation at 80 RPM ("1g" plus net shear force approx.30 dynes/sq cm). Following incubation, T cells were stained for CD25 expression (BD) and intracellular calcium (ratio of Fluo4 to Fura Red, Molecular Probes, Eugene, OR) and analyzed by flow cytometry (Coulter EPICS XL, Miami, FL). Results: Static or "1g" T cells had the highest level of CD25 expression and intracellular calcium. T cells centrifuged at 10 RCF ("10g") had lower CD25 expression and calcium levels compared to the static control. However, cells centrifuged at 10 RCF had higher CD25 expression and calcium levels than those exposed to 24 RPM clinorotation ("0g"). T cells exposed to 24 RPM clinorotation had lower CD25 expression, but the approximately the same calcium levels than T cells exposed to 80 RPM clinorotation. These data suggest that stress-activated calcium channel exist in T cells and may play a role during T cell activation.

  17. Telomeres and telomerase: Biological and clinical importance in dogs.

    Science.gov (United States)

    Nasir, Lubna

    2008-02-01

    In recent years in human oncology the enzyme telomerase has emerged as an ideal target for cancer therapy. This has led to the assessment of telomerase in cancers in companion animals, mainly dogs and these studies confirm that in dogs, like humans, telomere maintenance by telomerase is the primary mechanism by which cancer cells overcome their mortality and extend their lifespan. This review aims to provide an introduction to the biology of telomeres and telomerase and to discuss some of the telomere/telomerase directed therapeutic methodologies currently under development which may be of benefit to the canine cancer patient.

  18. A trans-spliced telomerase RNA dictates telomere synthesis in Trypanosoma brucei

    Institute of Scientific and Technical Information of China (English)

    Ranjodh Sandhu; Samantha Sanford; Shrabani Basu; MinA Park; Unnati M Pandya; Bibo Li; Kausik Chakrabarti

    2013-01-01

    Telomerase is a ribonucleoprotein enzyme typically required for sustained cell proliferation.Although both telomerase activity and the telomerase catalytic protein component,TbTERT,have been identified in the eukaryotic pathogen Trypanosoma brucei,the RNA molecule that dictates telomere synthesis remains unknown.Here,we identify the RNA component of Trypanosoma brucei telomerase,TbTR,and provide phylogenetic and in vivo evidence for TbTR's native folding and activity.We show that TbTR is processed through trans-splicing,and is a capped transcript that interacts and copurifies with TbTERT in vivo.Deletion of TbTR caused progressive shortening of telomeres at a rate of 3-5 bp/population doubling (PD),which can be rescued by ectopic expression of a wild-type allele of TbTR in an apparent dose-dependent manner.Remarkably,introduction of mutations in the TbTR template domain resulted in corresponding mutant telomere sequences,demonstrating that telomere synthesis in T.brucei is dependent on TbTR.We also propose a secondary structure model for TbTR based on phylogenetic analysis and chemical probing experiments,thus defining TbTR domains that may have important functional implications in telomere synthesis.Identification and characterization of TbTR not only provide important insights into T.brucei telomere functions,which have been shown to play important roles in T.brucei pathogenesis,but also offer T.brucei as an attractive model system for studying telomerase biology in pathogenic protozoa and for comparative analysis of telomerase function with higher eukaryotes.

  19. A trans-spliced telomerase RNA dictates telomere synthesis in Trypanosoma brucei

    Science.gov (United States)

    Sandhu, Ranjodh; Sanford, Samantha; Basu, Shrabani; Park, MinA; Pandya, Unnati M; Li, Bibo; Chakrabarti, Kausik

    2013-01-01

    Telomerase is a ribonucleoprotein enzyme typically required for sustained cell proliferation. Although both telomerase activity and the telomerase catalytic protein component, TbTERT, have been identified in the eukaryotic pathogen Trypanosoma brucei, the RNA molecule that dictates telomere synthesis remains unknown. Here, we identify the RNA component of Trypanosoma brucei telomerase, TbTR, and provide phylogenetic and in vivo evidence for TbTR's native folding and activity. We show that TbTR is processed through trans-splicing, and is a capped transcript that interacts and copurifies with TbTERT in vivo. Deletion of TbTR caused progressive shortening of telomeres at a rate of 3-5 bp/population doubling (PD), which can be rescued by ectopic expression of a wild-type allele of TbTR in an apparent dose-dependent manner. Remarkably, introduction of mutations in the TbTR template domain resulted in corresponding mutant telomere sequences, demonstrating that telomere synthesis in T. brucei is dependent on TbTR. We also propose a secondary structure model for TbTR based on phylogenetic analysis and chemical probing experiments, thus defining TbTR domains that may have important functional implications in telomere synthesis. Identification and characterization of TbTR not only provide important insights into T. brucei telomere functions, which have been shown to play important roles in T. brucei pathogenesis, but also offer T. brucei as an attractive model system for studying telomerase biology in pathogenic protozoa and for comparative analysis of telomerase function with higher eukaryotes. PMID:23478302

  20. Shared Subunits of Tetrahymena Telomerase Holoenzyme and Replication Protein A Have Different Functions in Different Cellular Complexes.

    Science.gov (United States)

    Upton, Heather E; Chan, Henry; Feigon, Juli; Collins, Kathleen

    2017-01-06

    In most eukaryotes, telomere maintenance relies on telomeric repeat synthesis by a reverse transcriptase named telomerase. To synthesize telomeric repeats, the catalytic subunit telomerase reverse transcriptase (TERT) uses the RNA subunit (TER) as a template. In the ciliate Tetrahymena thermophila, the telomerase holoenzyme consists of TER, TERT, and eight additional proteins, including the telomeric repeat single-stranded DNA-binding protein Teb1 and its heterotrimer partners Teb2 and Teb3. Teb1 is paralogous to the large subunit of the general single-stranded DNA binding heterotrimer replication protein A (RPA). Little is known about the function of Teb2 and Teb3, which are structurally homologous to the RPA middle and small subunits, respectively. Here, epitope-tagging Teb2 and Teb3 expressed at their endogenous gene loci enabled affinity purifications that revealed that, unlike other Tetrahymena telomerase holoenzyme subunits, Teb2 and Teb3 are not telomerase-specific. Teb2 and Teb3 assembled into other heterotrimer complexes, which when recombinantly expressed had the general single-stranded DNA binding activity of RPA complexes, unlike the telomere-specific DNA binding of Teb1 or the TEB heterotrimer of Teb1, Teb2, and Teb3. TEB had no more DNA binding affinity than Teb1 alone. In contrast, heterotrimers reconstituted with Teb2 and Teb3 and two other Tetrahymena RPA large subunit paralogs had higher DNA binding affinity than their large subunit alone. Teb1 and TEB, but not RPA, increased telomerase processivity. We conclude that in the telomerase holoenzyme, instead of binding DNA, Teb2 and Teb3 are Teb1 assembly factors. These findings demonstrate that Tetrahymena telomerase holoenzyme and RPA complexes share subunits and that RPA subunits have distinct functions in different heterotrimer assemblies. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. A transposable element within the Non-canonical telomerase RNA of Arabidopsis thaliana modulates telomerase in response to DNA damage [corrected].

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    Hengyi Xu

    2015-06-01

    Full Text Available Long noncoding RNAs (lncRNAs have emerged as critical factors in many biological processes, but little is known about how their regulatory functions evolved. One of the best-studied lncRNAs is TER, the essential RNA template for telomerase reverse transcriptase. We previously showed that Arabidopsis thaliana harbors three TER isoforms: TER1, TER2 and TER2S. TER1 serves as a canonical telomere template, while TER2 is a novel negative regulator of telomerase activity, induced in response to double-strand breaks (DSBs. TER2 contains a 529 nt intervening sequence that is removed along with 36 nt at the RNA 3' terminus to generate TER2S, an RNA of unknown function. Here we investigate how A. thaliana TER2 acquired its regulatory function. Using data from the 1,001 Arabidopsis genomes project, we report that the intervening sequence within TER2 is derived from a transposable element termed DSB responsive element (DRE. DRE is found in the TER2 loci of most but not all A. thaliana accessions. By analyzing accessions with (TER2 and without DRE (TER2Δ we demonstrate that this element is responsible for many of the unique properties of TER2, including its enhanced binding to TERT and telomerase inhibitory function. We show that DRE destabilizes TER2, and further that TER2 induction by DNA damage reflects increased RNA stability and not increased transcription. DRE-mediated changes in TER2 stability thus provide a rapid and sensitive switch to fine-tune telomerase enzyme activity. Altogether, our data shows that invasion of the TER2 locus by a small transposon converted this lncRNA into a DNA damage sensor that modulates telomerase enzyme activity in response to genome assault.

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

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    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

  3. Acutely decreased thermoregulatory energy expenditure or decreased activity energy expenditure both acutely reduce food intake in mice.

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    Karl J Kaiyala

    Full Text Available Despite the suggestion that reduced energy expenditure may be a key contributor to the obesity pandemic, few studies have tested whether acutely reduced energy expenditure is associated with a compensatory reduction in food intake. The homeostatic mechanisms that control food intake and energy expenditure remain controversial and are thought to act over days to weeks. We evaluated food intake in mice using two models of acutely decreased energy expenditure: 1 increasing ambient temperature to thermoneutrality in mice acclimated to standard laboratory temperature or 2 exercise cessation in mice accustomed to wheel running. Increasing ambient temperature (from 21 °C to 28 °C rapidly decreased energy expenditure, demonstrating that thermoregulatory energy expenditure contributes to both light cycle (40 ± 1% and dark cycle energy expenditure (15 ± 3% at normal ambient temperature (21 °C. Reducing thermoregulatory energy expenditure acutely decreased food intake primarily during the light cycle (65 ± 7%, thus conflicting with the delayed compensation model, but did not alter spontaneous activity. Acute exercise cessation decreased energy expenditure only during the dark cycle (14 ± 2% at 21 °C; 21 ± 4% at 28 °C, while food intake was reduced during the dark cycle (0.9 ± 0.1 g in mice housed at 28 °C, but during the light cycle (0.3 ± 0.1 g in mice housed at 21 °C. Cumulatively, there was a strong correlation between the change in daily energy expenditure and the change in daily food intake (R(2 = 0.51, p<0.01. We conclude that acutely decreased energy expenditure decreases food intake suggesting that energy intake is regulated by metabolic signals that respond rapidly and accurately to reduced energy expenditure.

  4. 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

  5. Transcript Regulation of Human Telomerase Reverse Transcriptase by c-myc and mad1

    Institute of Scientific and Technical Information of China (English)

    Lin ZOU; Peng-Hui ZHANG; Chun-Li LUO; Zhi-Guang TU

    2005-01-01

    Telomerase activity is highly positive correlated to most malignant neoplasms. Human telomerase reverse transcriptase (hTERT) is the rate-limiting factor of telomerase activity. Recent studies have shown that the expression of hTERT is mainly determined by its transcript regulation. Among the transcript regulation factors of hTERT, c-myc and mad1 are well known. Here, we constructed c-myc and mad1 eukaryotic expression vectors, then co-transfected them with the wild-type (Tw) or mutant hTERT promoter (Td)luciferase reporter plasmid, which were double-mutated in the E-box sequences from CACGTG to CACCTG of Tw. The change of luciferase activity in different cells was detected. The results showed that Tw was obviously activated in T24 and EJ bladder cancer cells, but not in normal fibrocytes. c-myc and mad1 had positive and negative effects respectively on the Tw transcript in a dose-dependent manner, while the roles of c-myc and mad1 in regulating the Td transcript were reversed. c-myc combined with mad1 can downregulate Tw but not Td. These observations indicate that c-myc and mad1 can regulate the hTERT transcript in a different manner in hTERT positive cells, but not in normal cells. This may provide an insight into some telomerase-related carcinogenesis mechanisms.

  6. Telomere-independent functions of telomerase in nuclei, cytoplasm, and mitochondria.

    Science.gov (United States)

    Chiodi, Ilaria; Mondello, Chiara

    2012-01-01

    Telomerase canonical activity at telomeres prevents telomere shortening, allowing chromosome stability and cellular proliferation. To perform this task, the catalytic subunit (telomerase reverse transcriptase, TERT) of the enzyme works as a reverse transcriptase together with the telomerase RNA component (TERC), adding telomeric repeats to DNA molecule ends. Growing evidence indicates that, besides the telomeric-DNA synthesis activity, TERT has additional functions in tumor development and is involved in many different biological processes, among which cellular proliferation, gene expression regulation, and mitochondrial functionality. TERT has been shown to act independently of TERC in the Wnt-β-catenin signaling pathway, regulating the expression of Wnt target genes, which play a role in development and tumorigenesis. Moreover, TERT RNA-dependent RNA polymerase activity has been found, leading to the genesis of double-stranded RNAs that act as precursor of silencing RNAs. In mitochondria, a TERT TERC-independent reverse transcriptase activity has been described that could play a role in the protection of mitochondrial integrity. In this review, we will discuss some of the extra-telomeric functions of telomerase.

  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. 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.

  9. 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

  10. Telomerase recruitment requires both TCAB1 and Cajal bodies independently.

    Science.gov (United States)

    Stern, J Lewis; Zyner, Katherine G; Pickett, Hilda A; Cohen, Scott B; Bryan, Tracy M

    2012-07-01

    The ability of most cancer cells to grow indefinitely relies on the enzyme telomerase and its recruitment to telomeres. In human cells, recruitment depends on the Cajal body RNA chaperone TCAB1 binding to the RNA subunit of telomerase (hTR) and is also thought to rely on an N-terminal domain of the catalytic subunit, hTERT. We demonstrate that coilin, an essential structural component of Cajal bodies, is required for endogenous telomerase recruitment to telomeres but that overexpression of telomerase can compensate for Cajal body absence. In contrast, recruitment of telomerase was sensitive to levels of TCAB1, and this was not rescued by overexpression of telomerase. Thus, although Cajal bodies are important for recruitment, TCAB1 has an additional role in this process that is independent of these structures. TCAB1 itself localizes to telomeres in a telomerase-dependent but Cajal body-independent manner. We identify a point mutation in hTERT that largely abolishes recruitment yet does not affect association of telomerase with TCAB1, suggesting that this region mediates recruitment by an independent mechanism. Our results demonstrate that telomerase has multiple independent requirements for recruitment to telomeres and that the function of TCAB1 is to directly transport telomerase to telomeres.

  11. Value of endoscopic methylene blue and Lugol's iodine double staining and detection of GST-Π and telomerase in the early diagnosis of esophageal carcinoma

    OpenAIRE

    Zhu, Xuan; Zhang, Shuang-Hong; ZHANG, KUN-HE; Li, Bi-Ming; Chen, Jiang

    2005-01-01

    AIM: To explore the expressions of GST-Π and telomerase activity in esophageal carcinoma and premalignant lesions and to investigate the value of endoscopic methylene blue (MB) and Lugol's iodine double staining.

  12. [The expression of human telomerase reverse transcriptase mRNA and its significance in acute leukemia].

    Science.gov (United States)

    Meng, Xiao-Li; Lin, Mao-Fang; Jin, Jie

    2003-02-01

    To investigate the expression of hTERT mRNA in bone marrow mononuclear cells (MNCs) from acute leukemia patients, the method of semi-quntitative RT-PCR was used to examine the expression of hTERT mRNA in marrow MNCs, and the telomerase activity of marrow MNCs was determined with the method of TRAP-PCR-ELISA by using a commercial kit. The results indicated that the expression of hTERT mRNA of marrow MNCs in 30 untreated AL patients was markedly higher than that in 12 CR cases (0.71 +/- 0.34 vs 0.43 +/- 0.25, P < 0.05) and 6 normal volunteers (0.71 +/- 0.34 vs 0.22 +/- 0.21, P < 0.01), respectively. Telomerase activity of marrow MNCs in 30 untreated AL patients was significantly higher than that in 12 CR cases (0.235 +/- 0.395 vs 0.012 +/- 0.015, P = 0.007). Moreover, there was a positive correlation between the hTERT mRNA synthesis and telomerase activity in AL cells (r = 0.421, P < 0.01). The pencentage of blast cells in marrow smear of the untreated AL patients was positively correlated with both the expression of hTERT mRNA and the telomerase activity of bone marrow MNCs (r = 0.457, P < 0.05 and r = 0.411, P < 0.05), respectively. It is concluded that the expression of hTERT mRNA in bone marrow MNCs from untreated AL patients was correlated with their telomerase activity. It is suggested that the expression of hTERT mRNA leukemic cells indicates their higher proliferation ability.

  13. 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.

  14. 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.

  15. The level of telomere dysfunction determines the efficacy of telomerase-based therapeutics in a lung cancer cell line.

    Science.gov (United States)

    Pantic, Milena; Zimmermann, Stefan; Waller, Cornelius F; Martens, Uwe M

    2005-05-01

    Telomerase is the ribonucleoprotein enzyme that maintains telomeres of eukaryotic chromosomes. Activation of telomerase is a common feature of the majority of human cancers, and inhibition of this enzyme has been proposed as a novel target for cancer therapeutics. Here, we investigated the effects of telomerase inhibition in the non-small cell lung cancer cell line NCI-H460, using a genetic approach by ectopic expression of dominant-negative (DN)-hTERT. Five clones were selected in which telomerase activity was completely abolished. As a result, telomere erosion was observed leading to proliferation arrest after a lag period of 20-28 population doublings. Although overall telomere length was similar between the different clones as measured by quantitative fluorescence in situ hybridization (Q-FISH), striking differences were found in telomere length of individual chromosomes. In particular, lack of individual telomeres and formation of end-to-end fusions were variable. Interestingly, this level of individual telomere dysfunction was positively correlated with the remaining life span of the different clones in vitro. In addition, the amount of telomere dysfunction induced by DN-hTERT was twice as high compared to the small molecule telomerase inhibitor BIBR1532, which induced growth arrest after >100 population doublings. Thus, pharmacological strategies that aim at inhibition of telomerase in cancer cells should take into account that not only overall telomere shortening, but rapid induction of a high level telomere dysfunction appears to be the crucial surrogate parameter for the development of future telomerase-based therapeutics.

  16. Imetelstat (GRN163L)--telomerase-based cancer therapy.

    Science.gov (United States)

    Röth, Alexander; Harley, Calvin B; Baerlocher, Gabriela M

    2010-01-01

    Telomeres and telomerase play essential roles in the regulation of the lifespan of human cells. While normal human somatic cells do not or only transiently express telomerase and therefore shorten their telomeres with each cell division, most human cancer cells typically express high levels of telomerase and show unlimited cell proliferation. High telomerase expression allows cells to proliferate and expand long-term and therefore supports tumor growth. Owing to the high expression and its role, telomerase has become an attractive diagnostic and therapeutic cancer target. Imetelstat (GRN163L) is a potent and specific telomerase inhibitor and so far the only drug of its class in clinical trials. Here, we report on the structure and the mechanism of action of imetelstat as well as about the preclinical and clinical data and future prospects using imetelstat in cancer therapy.

  17. Dose-Dependent Cytotoxic Effects of Boldine in HepG-2 Cells—Telomerase Inhibition and Apoptosis Induction

    Directory of Open Access Journals (Sweden)

    Sakineh Kazemi Noureini

    2015-02-01

    Full Text Available Plant metabolites are valuable sources of novel therapeutic compounds. In an anti-telomerase screening study of plant secondary metabolites, the aporphine alkaloid boldine (1,10-dimethoxy-2,9-dihydroxyaporphine exhibited a dose and time dependent cytotoxicity against hepatocarcinoma HepG-2 cells. Here we focus on the modes and mechanisms of the growth-limiting effects of this compound. Telomerase activity and expression level of some related genes were estimated by real-time PCR. Modes of cell death also were examined by microscopic inspection, staining methods and by evaluating the expression level of some critically relevant genes. The growth inhibition was correlated with down-regulation of the catalytic subunit of telomerase (hTERT gene (p < 0.01 and the corresponding reduction of telomerase activity in sub-cytotoxic concentrations of boldine (p < 0.002. However, various modes of cell death were stimulated, depending on the concentration of boldine. Very low concentrations of boldine over a few passages resulted in an accumulation of senescent cells so that HepG-2 cells lost their immortality. Moreover, boldine induced apoptosis concomitantly with increasing the expression of bax/bcl2 (p < 0.02 and p21 (p < 0.01 genes. Boldine might thus be an interesting candidate as a potential natural compound that suppresses telomerase activity in non-toxic concentrations.

  18. 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.

  19. 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

    2016-04-07

    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 telomerase Tert gene in 2 independent mouse models of aplastic anemia due to short telomeres (Trf1- and Tert-deficient mice). We find that a high dose of AAV9-Tert targets the bone marrow compartment, including hematopoietic stem cells. AAV9-Tert treatment 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.

  20. Telomeres and Telomerase: Role in Marek’s Disease Virus Pathogenesis, Integration and Tumorigenesis

    Directory of Open Access Journals (Sweden)

    Ahmed Kheimar

    2017-07-01

    Full Text Available Telomeres protect the ends of vertebrate chromosomes from deterioration and consist of tandem nucleotide repeats (TTAGGGn that are associated with a number of proteins. Shortening of the telomeres occurs during genome replication, thereby limiting the replication potential of somatic cells. To counteract this shortening, vertebrates encode the telomerase complex that maintains telomere length in certain cell types via de novo addition of telomeric repeats. Several herpesviruses, including the highly oncogenic alphaherpesvirus Marek’s disease virus (MDV, harbor telomeric repeats (TMR identical to the host telomere sequences at the ends of their linear genomes. These TMR facilitate the integration of the MDV genome into host telomeres during latency, allowing the virus to persist in the host for life. Integration into host telomeres is critical for disease and tumor induction by MDV, but also enables efficient reactivation of the integrated virus genome. In addition to the TMR, MDV also encodes a telomerase RNA subunit (vTR that shares 88% sequence identity with the telomerase RNA in chicken (chTR. vTR is highly expressed during all stages of the virus lifecycle, enhances telomerase activity and plays an important role in MDV-induced tumor formation. This review will focus on the recent advances in understanding the role of viral TMR and vTR in MDV pathogenesis, integration and tumorigenesis.

  1. Telomeres and Telomerase: Role in Marek's Disease Virus Pathogenesis, Integration and Tumorigenesis.

    Science.gov (United States)

    Kheimar, Ahmed; Previdelli, Renato L; Wight, Darren J; Kaufer, Benedikt B

    2017-07-04

    Telomeres protect the ends of vertebrate chromosomes from deterioration and consist of tandem nucleotide repeats (TTAGGG)n that are associated with a number of proteins. Shortening of the telomeres occurs during genome replication, thereby limiting the replication potential of somatic cells. To counteract this shortening, vertebrates encode the telomerase complex that maintains telomere length in certain cell types via de novo addition of telomeric repeats. Several herpesviruses, including the highly oncogenic alphaherpesvirus Marek's disease virus (MDV), harbor telomeric repeats (TMR) identical to the host telomere sequences at the ends of their linear genomes. These TMR facilitate the integration of the MDV genome into host telomeres during latency, allowing the virus to persist in the host for life. Integration into host telomeres is critical for disease and tumor induction by MDV, but also enables efficient reactivation of the integrated virus genome. In addition to the TMR, MDV also encodes a telomerase RNA subunit (vTR) that shares 88% sequence identity with the telomerase RNA in chicken (chTR). vTR is highly expressed during all stages of the virus lifecycle, enhances telomerase activity and plays an important role in MDV-induced tumor formation. This review will focus on the recent advances in understanding the role of viral TMR and vTR in MDV pathogenesis, integration and tumorigenesis.

  2. Juglans mandshurica Maxim extracts exhibit antitumor activity on HeLa cells in vitro.

    Science.gov (United States)

    Xin, Nian; Hasan, Murtaza; Li, Wei; Li, Yan

    2014-04-01

    The present study examined the potential application of Juglans mandshurica Maxim extracts (HT) for cancer therapy by assessing their anti‑proliferative activity, reduction of telomerase activity, induction of apoptosis and cell cycle arrest in S phase in HeLa cells. From the perspective of using HT as a herbal medicine, photomicroscopy and florescent microscopy techniques were utilized to characterize the effect of the extracts on telomerase activity and cell morphology. Flow cytometry was employed to study apoptosis and cell cycle of HeLa cells, and DNA laddering was performed. The results showed that HT inhibited cell proliferation and telomerase activity, induced apoptosis and caused S phase arrest of HeLa cells in vitro. HT inhibited HeLa cell proliferation significantly, and the highest inhibition rate was 83.7%. A trap‑silver staining assay showed that HT was capable of markedly decreasing telomerase activity of HeLa cells and this inhibition was enhanced in a time‑ and dose‑dependent manner. Results of a Hoechst 33258 staining assay showed that HeLa cells treated by HT induced cell death. Through DNA agarose gel electrophoresis, DNA ladders of HeLa cells treated with HT were observed, indicating apoptosis. In conclusion, the present study demonstrated that HT exhibited anti‑tumor effects comprising the inhibition of growth and telomerase activity as well as apoptosis and cell cycle arrest in HeLa cells.

  3. Brain-derived Neurotrophic Factor Signaling Pathway: Modulation by Acupuncture in Telomerase Knockout Mice.

    Science.gov (United States)

    Lin, Dong; Wu, Qiang; Lin, Xiaoyang; Borlongan, Cesar V; He, Zhi-Xu; Tan, Jun; Cao, Chuanhai; Zhou, Shu-Feng

    2015-01-01

    through the activation of BDNF and its downstream signaling pathways in populations of patients who exhibit low telomerase activity.

  4. Chromosomal imbalances in primary and metastatic melanomas: over-representation of essential telomerase genes.

    Science.gov (United States)

    Pirker, Christine; Holzmann, Klaus; Spiegl-Kreinecker, Sabine; Elbling, Leonilla; Thallinger, Christiane; Pehamberger, Hubert; Micksche, Michael; Berger, Walter

    2003-10-01

    Comparative genomic hybridization was used to map copy number abnormalities in 48 short-term cell cultures established from different stages and types of human melanoma. A variety of random and non-random chromosomal alterations were detected, with gains within chromosomes 20q, 7q, 7p, 20p, 6p and 17q and losses in 9p, 10q, 6q, 10p, 4q, and 11q being the most common observations. In addition, several other chromosomal loci were over- or under-represented in subgroups of melanomas. For example, sequences on 3q26 were over-represented in 33% and on 5p15.33 in 27% of cell cultures, reaching the level of amplification in 12% and 22%, respectively. These regions harbour the two essential genes for the enzyme telomerase: the telomerase reverse transcriptase gene (hTERT) on 5p15.33 and the telomerase RNA component gene (hTERC) on 3q26. Using fluorescence in situ hybridization and Southern blot analysis, both genes were shown to be over-represented or amplified in several melanomas. Interestingly, hTERT amplification was abundant in superficial spreading primary melanomas, subcutaneous metastases and malignant effusion-derived cells, but completely absent or very rare in primary nodular melanomas as well as brain, bone and lymph node metastases. Several chromosomes or chromosomal regions harbouring telomerase-suppressing activities (3p, 4, 6 and 10p) were frequently under-represented in melanomas. Our data suggest that genetic alterations at several chromosomal loci might facilitate activation of telomerase during the development of cutaneous malignant melanoma.

  5. Modulation of telomere shelterin by TRF1 [corrected] and TRF2 interacts with telomerase to maintain the telomere length in non-small cell lung cancer.

    Science.gov (United States)

    Hsu, Chung-Ping; Ko, Jiunn-Liang; Shai, Sen-Ei; Lee, Li-Wen

    2007-12-01

    Our previous report demonstrated good correlations between the expressions of h-TERT and its associated genes, such as c-Myc, TRF1 and TRF2. To observe the interaction between telomerase activity and expression of its associated genes in regulation of the telomere restriction fragment length (TRFL) in non-small cell lung cancer (NSCLC), 79 NSCLC specimens were examined. Telomerase activity, h-TERT, TRF1 and TRF2 genes expression were observed in 60.8, 66.7, 74.7, and 83.5% of the tumour tissues, respectively. The TRFL were shorter in both tumour tissues and telomerase positive tissues, as compared to their counterparts. The t/n-TRFLR (tumour-to-normal TRFL ratio) was also lower in telomerase positive tissues. When telomerase was negative, the t/n-TRFLR was lower in both TRF1 positive and TFR2 positive. However, when telomerase was positive, the t/n-TRFLR was only lower in the TFR2 positive group. When t/n-TRFLR level was equal to or less than 75%, the majority of the specimens became TRF1 and TRF2 positive. To explain these findings, our hypothesis is that when the TRF length becomes shorter during tumour progression, the tumour cells can sustain a better tolerance to shorter telomere with the help of both TRF1 and TRF2, but without immediate activation of the telomerase. However, when the TRF length reaches a critical level, changing the telomere shelterin by persistent expression of the TRF2, which in combination with telomerase activation reverses the telomere shortening.

  6. Culture of Human Tendon Cell Transfected by Human Telomerase Reverse Transcriptase Plasmid and their Biological Characteristics In Vitro

    Institute of Scientific and Technical Information of China (English)

    Hui-Qi XIE; Zhi-Ming YANG; Fan LIN; Yi QU

    2005-01-01

    @@ 1 Introduction The proliferative and functional characteristics of tendon cell are the key issue in the research of tissue engineered tendon. The standard tendon cell line, which has normal functional characteristics, and can be subcultured continuously and permanently, will not only meet the demands of seeding cell in tissue engineered tendon,but also control the variable of tendon cell. In our previous study, it showed that the proliferative ability of human tendon cell cultured in vitro is depressed gradually after subcultured to the 13th passage, which can not meet the demands of tendon tissue engineering. It has been proved that replicative senescence of cells was closely related to the activity of telomerase. We constructed pGRN145 plasmid which contain total human telomerase reverse transcriptase (hTERT) cDNA. We transfected it into human tendon cells to investigate the feasibility of life span extension by reconstitution of the telomerase activity.

  7. Defining the Regulation of Telomerase Through Identification of Mammary-Specific Telomerase Interacting Proteins

    Science.gov (United States)

    2007-06-01

    Studying Telomeres and Telomerase. Zebrafish , 1:349-355. Jones,K.R., L.W.Elmore, L.Povirk, S.E.Holt, and D.A.Gewirtz. 2005. Reciprocal regulation... Zebrafish Blastula Cell Line on Rainbow Trout Stromal Cells and Subsequent Development under Feeder-Free Conditions into a Cell Line, ZEB2J. Zebrafish 5: 49...63. Elmore,L.W., M.Norris, A.T.Bright, P.A.McChesney, R.Winn, and S.E.Holt. 2008. Upregulation of Telomerase Function during Tissue Regeneration in

  8. Promotion of cell proliferation by HBXIP via upregulation of human telomerase reverse transcriptase in human mesenchymal stem cells1

    Institute of Scientific and Technical Information of China (English)

    Feng-ze WANG; Li SHA; Li-hong YE; Xiao-dong ZHANG

    2008-01-01

    Aim: We previously found that the hepatitis B X-interacting protein (HBXIP) was able to promote the proliferation of cells. Telomerase activity is known to be critical in cellular senescence and its level is modulated by the regulation of the telomerase catalytic subunit, telomerase reverse transcriptase (TERT), at both the transcriptional and post-transcriptional levels. To investigate the mechanism of promoting proliferation by HBXIP, the effect of HBXIP on human TERT (hTERT) was investigated in human mesenchymal stem cells (hMSC). Methods: BMMS-03 cells and hMSC from the bone marrow of a 4-month-old elicited fetus, were tran-siently transfected with the pcDNA3-hbxip plasmid encoding the HBXIP gene and pSilencer-hbxip plasmid encoding RNA interference (RNAi) targeting HBXIP mRNA, followed by the examination of the hTERT promoter reporter gene by luciferase assay, and the detection of telomerase activity by telomeric repeat amplication protocol, respectively, as well as the expression levels of hTERT, c-Myc, and Bcl-2 by Western blot analysis. Results: The overexpression of HBXIP led to a significant upregulation of hTERT promoter activity, telomerase activity, and the expression levels of hTERT, c-Myc, and Bcl-2 in BMMS-03 cells. RNAi target-ing HBXIP mRNA produced the opposite results completely. Conclusion: Our data demonstrated that HBXIP significantly stimulated the transcription and ex-pression of hTERT and increased the activity of telomerase in BMMS-03 cells, which provides a new insight into the mechanism of promoting cell proliferation by HBXIP.

  9. Identification of telomerase RNAs from filamentous fungi reveals conservation with vertebrates and yeasts.

    Directory of Open Access Journals (Sweden)

    Paulius V Kuprys

    Full Text Available Telomeres are the nucleoprotein complexes at eukaryotic chromosomal ends. Telomeric DNA is synthesized by the ribonucleoprotein telomerase, which comprises a telomerase reverse transcriptase (TERT and a telomerase RNA (TER. TER contains a template for telomeric DNA synthesis. Filamentous fungi possess extremely short and tightly regulated telomeres. Although TERT is well conserved between most organisms, TER is highly divergent and thus difficult to identify. In order to identify the TER sequence, we used the unusually long telomeric repeat sequence of Aspergillus oryzae together with reverse-transcription-PCR and identified a transcribed sequence that contains the potential template within a region predicted to be single stranded. We report the discovery of TERs from twelve other related filamentous fungi using comparative genomic analysis. These TERs exhibited strong conservation with the vertebrate template sequence, and two of these potentially use the identical template as humans. We demonstrate the existence of important processing elements required for the maturation of yeast TERs such as an Sm site, a 5' splice site and a branch point, within the newly identified TER sequences. RNA folding programs applied to the TER sequences show the presence of secondary structures necessary for telomerase activity, such as a yeast-like template boundary, pseudoknot, and a vertebrate-like three-way junction. These telomerase RNAs identified from filamentous fungi display conserved structural elements from both yeast and vertebrate TERs. These findings not only provide insights into the structure and evolution of a complex RNA but also provide molecular tools to further study telomere dynamics in filamentous fungi.

  10. Pyrimidine motif triple helix in the Kluyveromyces lactis telomerase RNA pseudoknot is essential for function in vivo.

    Science.gov (United States)

    Cash, Darian D; Cohen-Zontag, Osnat; Kim, Nak-Kyoon; Shefer, Kinneret; Brown, Yogev; Ulyanov, Nikolai B; Tzfati, Yehuda; Feigon, Juli

    2013-07-02

    Telomerase is a ribonucleoprotein complex that extends the 3' ends of linear chromosomes. The specialized telomerase reverse transcriptase requires a multidomain RNA (telomerase RNA, TER), which includes an integral RNA template and functionally important template-adjacent pseudoknot. The structure of the human TER pseudoknot revealed that the loops interact with the stems to form a triple helix shown to be important for activity in vitro. A similar triple helix has been predicted to form in diverse fungi TER pseudoknots. The solution NMR structure of the Kluyveromyces lactis pseudoknot, presented here, reveals that it contains a long pyrimidine motif triple helix with unexpected features that include three individual bulge nucleotides and a C(+)•G-C triple adjacent to a stem 2-loop 2 junction. Despite significant differences in sequence and base triples, the 3D shape of the human and K. lactis TER pseudoknots are remarkably similar. Analysis of the effects of nucleotide substitutions on cell growth and telomere lengths provides evidence that this conserved structure forms in endogenously assembled telomerase and is essential for telomerase function in vivo.

  11. The MAPK pathway signals telomerase modulation in response to isothiocyanate-induced DNA damage of human liver cancer cells.

    Directory of Open Access Journals (Sweden)

    Evelyn Lamy

    Full Text Available 4-methylthiobutyl isothiocyanate (MTBITC, an aliphatic, sulphuric compound from Brassica vegetables, possesses in vitro and in vivo antitumor activity. Recently we demonstrated the potent growth inhibitory potential of the DNA damaging agent MTBITC in human liver cancer cells. Here we now show that MTBITC down regulates telomerase which sensitizes cells to apoptosis induction. This is mediated by MAPK activation but independent from production of reactive oxygen species (ROS. Within one hour, MTBITC induced DNA damage in cancer cells correlating to a transient increase in hTERT mRNA expression which then turned into telomerase suppression, evident at mRNA as well as enzyme activity level. To clarify the role of MAPK for telomerase regulation, liver cancer cells were pre-treated with MAPK-specific inhibitors prior to MTBITC exposure. This clearly showed that transient elevation of hTERT mRNA expression was predominantly mediated by the MAPK family member JNK. In contrast, activated ERK1/2 and P38, but not JNK, signalled to telomerase abrogation and consequent apoptosis induction. DNA damage by MTBITC was also strongly abolished by MAPK inhibition. Oxidative stress, as analysed by DCF fluorescence assay, electron spin resonance spectroscopy and formation of 4-hydroxynonenal was found as not relevant for this process. Furthermore, N-acetylcysteine pre-treatment did not impact MTBITC-induced telomerase suppression or depolarization of the mitochondrial membrane potential as marker for apoptosis. Our data therefore imply that upon DNA damage by MTBITC, MAPK are essential for telomerase regulation and consequent growth impairment in liver tumor cells and this detail probably plays an important role in understanding the potential chemotherapeutic efficacy of ITC.

  12. 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.

  13. A Case of Angioedema Associated with Decreased C1 Inhibitor Activity

    Directory of Open Access Journals (Sweden)

    Chizuko Yano

    2007-01-01

    Discussion: Based on the presence of the typical clinical features and the positive results on the complement tests, we diagnosed hereditary angioedema. A decrease in C1 inhibitor activity and an increase in specific protein concentrations indicated type 1.

  14. Statins decrease dendritic arborization in rat sympathetic neurons by blocking RhoA activation

    OpenAIRE

    Kim, Woo-Yang; Gonsiorek, Eugene A.; Barnhart, Chris; Davare, Monika A.; Engebose, Abby J.; Lauridsen, Holly; Bruun, Donald; Lesiak, Adam; Wayman, Gary; Bucelli, Robert; Higgins, Dennis; Lein, Pamela J.

    2009-01-01

    Clinical and experimental evidence suggest that statins decrease sympathetic activity, but whether peripheral mechanisms involving direct actions on post-ganglionic sympathetic neurons contribute to this effect is not known. Because tonic activity of these neurons is directly correlated with the size of their dendritic arbor, we tested the hypothesis that statins decrease dendritic arborization in sympathetic neurons. Oral administration of atorvastatin (20 mg/kg/day for 7 days) significantly...

  15. Structural Basis for Telomerase Catalytic Subunit TERT Binding to RNA Template and Telomeric DNA

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, M.; Gillis, A; Futahashi, M; Fujiwara, H; Skordalakes, E

    2010-01-01

    Telomerase is a specialized DNA polymerase that extends the 3{prime} ends of eukaryotic linear chromosomes, a process required for genomic stability and cell viability. Here we present the crystal structure of the active Tribolium castaneum telomerase catalytic subunit, TERT, bound to an RNA-DNA hairpin designed to resemble the putative RNA-templating region and telomeric DNA. The RNA-DNA hybrid adopts a helical structure, docked in the interior cavity of the TERT ring. Contacts between the RNA template and motifs 2 and B{prime} position the solvent-accessible RNA bases close to the enzyme active site for nucleotide binding and selectivity. Nucleic acid binding induces rigid TERT conformational changes to form a tight catalytic complex. Overall, TERT-RNA template and TERT-telomeric DNA associations are remarkably similar to those observed for retroviral reverse transcriptases, suggesting common mechanistic aspects of DNA replication between the two families of enzymes.

  16. Cancer Immunotherapy Targeting the Telomerase Reverse Transcriptase

    Institute of Scientific and Technical Information of China (English)

    Longfei Huo; Janice WS Tang; Junjian Huang; Peitang Huang; Cuifen Huang; Hsiang-fu Kung; Marie C. Lin

    2006-01-01

    The human telomerase reverse transcriptase (hTERT) is expressed in more than 85% of tumor cells but is usually not found in normal cells, which makes hTERT as an ideal tumor-associate antigen (TAA) to develop potential vaccine specifically destroying cancers without impairing normal tissues in human cancer immunotherapy. Here are reviewed the fundamental advances of studies on immunogenicity of hTERT or its peptides and the early clinical trials using the hTERT vaccine approach in the last decades.

  17. Profile of telomerase and telomerase RNA expression in nasopharyngeal carcinogen esis of rats induced by N, N'dinitrosopiperazine (DNP)%鼻咽上皮癌变过程中端粒酶活性和端粒酶RNA的表达

    Institute of Scientific and Technical Information of China (English)

    唐发清; 蒋海鹰; 段朝军; 谌兵来; 荆照政; 吴尚辉

    2001-01-01

    目的研究二亚硝基哌嗪(DNP)诱发大鼠鼻咽癌变过程中端粒酶的表达规律。方法以DNP诱导大鼠鼻咽癌;用PCR-ELISA 和Nested RT-PCR检测DNP诱导大鼠鼻咽癌变不同阶段端粒酶活性和端粒酶RNA的表达,同时作病理形态学检测。结果 DNP诱导大鼠鼻咽癌变过程中,端粒酶活性不断升高,端粒酶的变化与鼻咽癌变呈正相关,而且端粒酶中RNA表达先于端粒酶的表达。在大鼠鼻咽上皮细胞异型增生阶段即出现端粒酶的激活和端粒酶RNA的表达。结论化学致癌物DNP诱导细胞癌变端粒酶的激活,且端粒酶的激活和端粒酶RNA的表达是鼻咽上皮癌变的早发事件,与鼻咽癌的发生、发展有关。%Objective  To investigate the profile of telomerase and telomerase RNA expression in nasopharyngeal carcinogenesis (NPC) induced by N,N'dinitrosopi perazine (DNP) and examined histolofically. Methods Nasopharyngeal carcinomas o f rats were induced by DNP and examined histologically. PCR-ELISA and nested R T -PCR were used to assay telomerase and telomerase RNA expression at different s tages in the nasopharyngeal tissues of rats. Results  During the carcinogenesis p rocess, telomerase activity increased along with the formation of a nasopharynge al carcinoma. Telomerase expression was positively related with nasopharyngeal c arcinogenesis. Telomerase RNA expression was present and did not change during t he NPC process. Expression of telomease RNA was earlier than telomerase activat ion. Telomerase activation and telomerase RNA expressin were also detected in th e pre-cancerous nasopharyngeal lesions. Conclusion  Telomerase activation may p articipate in the onset and progression of NPC, and is an early step in NPC.

  18. Src activity increases and Yes activity decreases during mitosis of human colon carcinoma cells.

    OpenAIRE

    Park, J.; Cartwright, C A

    1995-01-01

    Src and Yes protein-tyrosine kinase activities are elevated in malignant and premalignant tumors of the colon. To determine whether Src activity is elevated throughout the human colon carcinoma cell cycle as it is in polyomavirus middle T antigen- or F527 Src-transformed cells, and whether Yes activity, which is lower than that of Src in the carcinoma cells, is regulated differently, we measured their activities in cycling cells. We observed that the activities of both kinases were higher thr...

  19. Using of Telomerase Enzyme in Urine as a Non invasive Marker for Cancer Bladder Detection

    Directory of Open Access Journals (Sweden)

    Azza A Hassan*, Fawzia A . El- Sheshtawey** , Seliem A. Seliem

    2008-12-01

    Full Text Available Background: Urinary bladder cancer is one of the major health problem all over the world. Cystoscopy remains the gold standard for identifying bladder cancer but it is invasive and expensive, therefore, a simple, non invasive test for detecting bladder cancer would be helpful. Several biomarkers for bladder cancer have been used, but no single marker has been accurate and conclusive. Aim: The current study aimed to measure telomerase enzyme in urine as a useful non invasive marker for detection of bladder cancer. Methods : Forty eight patients ( 39 males and 9 females were included, They are complaining of urinary symptoms and undergo cystoscopy with biopsy of bladder lesions and histopathological examination. They were divided into groups: Group I: 16 patients ( 11 males and 5 females have benign urologic conditions. Group II: 32 patients (28 males and 4 females have proven bladder cancer patients underwent transurethral resection of bladder tumor or cystoscopy with biopsy of bladder lesions. Also, 15 apparently healthy volunteers with matched age and sex with patients were served as a control group. All subjects were submitted to laboratory estimation of the following in urine: urinary creatinine, urine cytology, telomerase enzyme in urine by telomerase PCR and complete urine examination. Results : The results of this study revealed that a highly significant increase in the frequency of cytolological positive cases for tumor cells in malignant group than each of benign group and healthy subjects, while no significant difference was detected between benign group and healthy subjects. The frequency of telomerase in urine was significantly higher in malignant group than each of benign group and healthy subjects, while no significant difference was detected between benign group and healthy subjects. The telomerase activity has sensitivity of 90.6% for diagnosis of cancer bladder with 93.7% for specificity and PPV was 96.6%, NPV was 83.3% and

  20. Telomerase prevents accelerated senescence in glucose-6-phosphate dehydrogenase (G6PD-deficient human fibroblasts

    Directory of Open Access Journals (Sweden)

    Wu Yi-Hsuan

    2009-02-01

    Full Text Available Abstract Fibroblasts derived from glucose-6-phosphate dehydrogenase (G6PD-deficient patients display retarded growth and accelerated cellular senescence that is attributable to increased accumulation of oxidative DNA damage and increased sensitivity to oxidant-induced senescence, but not to accelerated telomere attrition. Here, we show that ectopic expression of hTERT stimulates telomerase activity and prevents accelerated senescence in G6PD-deficient cells. Stable clones derived from hTERT-expressing normal and G6PD-deficient fibroblasts have normal karyotypes, and display no sign of senescence beyond 145 and 105 passages, respectively. Activation of telomerase, however, does not prevent telomere attrition in earlier-passage cells, but does stabilize telomere lengths at later passages. In addition, we provide evidence that ectopic expression of hTERT attenuates the increased sensitivity of G6PD-deficient fibroblasts to oxidant-induced senescence. These results suggest that ectopic expression of hTERT, in addition to acting in telomere length maintenance by activating telomerase, also functions in regulating senescence induction.

  1. Heroin abuse accelerates biological aging: a novel insight from telomerase and brain imaging interaction.

    Science.gov (United States)

    Cheng, G L F; Zeng, H; Leung, M-K; Zhang, H-J; Lau, B W M; Liu, Y-P; Liu, G-X; Sham, P C; Chan, C C H; So, K-F; Lee, T M C

    2013-05-21

    Heroin abuse and natural aging exert common influences on immunological cell functioning. This observation led to a recent and untested idea that aging may be accelerated in abusers of heroin. We examined this claim by testing whether heroin use is associated with premature aging at both cellular and brain system levels. A group of abstinent heroin users (n=33) and matched healthy controls (n=30) were recruited and measured on various biological indicators of aging. These measures included peripheral blood telomerase activity, which reflects cellular aging, and both structural and functional measures of brain magnetic resonance imaging. We found that heroin users were characterized by significantly low telomerase activity (0.21 vs 1.78; 88% reduction; t(61)=6.96, Pbrain region implicated in aging. Using the PFC location identified from the structural analyses as a 'seed' region, it was further revealed that telomerase activity interacted with heroin use to impact age-sensitive brain functional networks (AlphaSim corrected Pbrain system and behavioral measures in the context of substance abuse. The present finding that heroin abuse is associated with accelerated aging at both cellular and brain system levels is novel and forms a unique contribution to our knowledge in how the biological processes of drug abusers may be disrupted.

  2. Water-Soluble Ruthenium(II) Complexes with Chiral 4-(2,3-Dihydroxypropyl)-formamide Oxoaporphine (FOA): In Vitro and in Vivo Anticancer Activity by Stabilization of G-Quadruplex DNA, Inhibition of Telomerase Activity, and Induction of Tumor Cell Apoptosis.

    Science.gov (United States)

    Chen, Zhen-Feng; Qin, Qi-Pin; Qin, Jiao-Lan; Zhou, Jie; Li, Yu-Lan; Li, Nan; Liu, Yan-Cheng; Liang, Hong

    2015-06-11

    Three water-soluble ruthenium(II) complexes with chiral 4-(2,3-dihydroxypropyl)-formamide oxoaporphine (FOA) were synthesized and characterized. It was found that these ruthenium(II) complexes exhibited considerable in vitro anticancer activities and that they were the effective stabilizers of telomeric and G-quadruplex-DNA (G4-DNA) in promoter of c-myc, which acted as a telomerase inhibitor targeting G4-DNA and induced cell senescence and apoptosis. Interestingly, the in vitro anticancer activity of 6 (LC-003) was higher than those of 4 (LC-001) and 5 (LC-002), more selective for BEL-7404 cells than for normal HL-7702 cells, and preferred to activate caspases-3/9. The different biological behaviors of the ruthenium complexes could be correlated with the chiral nature of 4-(2,3-dihydroxypropyl)-formamide oxoaporphine. More significantly, 6 exhibited effective inhibitory on tumor growth in BEL-7402 xenograft mouse model and higher in vivo safety than cisplatin. These mechanistic insights indicate that 6 displays low toxicity and can be a novel anticancer drug candidate.

  3. Decreased electrophysiological activity represents the conscious state of emptiness in meditation

    OpenAIRE

    Thilo eHinterberger; Stephanie eSchmidt; Tsutomu eKamei; Harald eWalach

    2014-01-01

    Many neuroscientific theories explain consciousness with higher order information processing corresponding to an activation of specific brain areas and processes. In contrast, most forms of meditation ask for a down-regulation of certain mental processing activities while remaining fully conscious. To identify the physiological properties of conscious states with decreased mental and cognitive processing, the electrical brain activity (64 channels of EEG) of 50 participants of various meditat...

  4. Correlations Decrease with Propagation of Spiking Activity in the Mouse Barrel Cortex

    Science.gov (United States)

    Ranganathan, Gayathri Nattar; Koester, Helmut Joachim

    2011-01-01

    Propagation of suprathreshold spiking activity through neuronal populations is important for the function of the central nervous system. Neural correlations have an impact on cortical function particularly on the signaling of information and propagation of spiking activity. Therefore we measured the change in correlations as suprathreshold spiking activity propagated between recurrent neuronal networks of the mammalian cerebral cortex. Using optical methods we recorded spiking activity from large samples of neurons from two neural populations simultaneously. The results indicate that correlations decreased as spiking activity propagated from layer 4 to layer 2/3 in the rodent barrel cortex. PMID:21629764

  5. Correlations decrease with propagation of spiking activity in the mouse barrel cortex

    Directory of Open Access Journals (Sweden)

    Gayathri Nattar Ranganathan

    2011-05-01

    Full Text Available Propagation of suprathreshold spiking activity through neuronal populations is important for the function of the central nervous system. Neural correlations have an impact on cortical function particularly on the signaling of information and propagation of spiking activity. Therefore we measured the change in correlations as suprathreshold spiking activity propagated between recurrent neuronal networks of the mammalian cerebral cortex. Using optical methods we recorded spiking activity from large samples of neurons from two neural populations simultaneously. The results indicate that correlations decreased as spiking activity propagated from layer 4 to layer 2/3 in the rodent barrel cortex.

  6. Estrogen deficiency leads to telomerase inhibition,telomere shortening and reduced cell proliferation in the adrenal gland of mice

    Institute of Scientific and Technical Information of China (English)

    Sharyn Bayne; Margaret EE Jones; He Li; Alex R Pinto; Evan R Simpson; Jun-Ping Liu

    2008-01-01

    Estrogen deficiency mediates aging, but the underlying mechanism remains to be fully determined. We report here that estrogen deficiency caused by targeted disruption of aromatase in mice results in significant inhibition oftelomerase activity in the adrenal gland in vivo. Gene expression analysis showed that, in the absence of estrogen, telomerase reverse transcriptase (TERT) gene expression is reduced in association with compromised cell proliferation in the adrenal gland cortex and adrenal atrophy. Stem cells positive in c-kit are identified to populate in the parenchyma of adrenal cortex. Analysis of telomeres revealed that estrogen deficiency results in significantly shorter telomeres in the adrenal cortex than that in wild-type (WT) control mice. To further establish the causal effects of estrogen, we conducted an estrogen replacement therapy in these estrogen-deficient animals. Administration of estrogen for 3 weeks restores TERT gene expression, telomerase activity and cell proliferation in estrogen-deficient mice. Thus, our data show for the first time that estrogen deficiency causes inhibitions of TERT gene expression, telomerase activity, telomere maintenance, and cell proliferation in the adrenal gland of mice in vivo, suggesting that telomerase inhibition and telomere shortening may mediate cell proliferation arrest in the adrenal gland, thus contributing to estrogen deficiency-induced aging under physiological conditions.

  7. Urine Telomerase: An Important Marker in the Diagnosis of Bladder Cancer

    Directory of Open Access Journals (Sweden)

    Maria Aurora Sanchini

    2004-05-01

    Full Text Available Telomerase activity is present in most human malignant tumors, whereas it is generally not detectable, with some exceptions, in normal cells. Therefore, it represents a potential tool for tumor detection. In the present study, telomerase activity was determined in urine from 79 healthy individuals and 121 previously untreated bladder cancer patients using a highly sensitive telomeric repeat amplification protocol (TRAP assay and the results were expressed as arbitrary enzymatic units (AEU. This approach enabled us to identify cutoff values characterized by high sensitivity (from 75% to 93% and specificity (from 72% to 92%. Moreover, analysis as a function of gender showed a higher accuracy of TRAP assay in males (93% sensitivity and 90% specificity at the cutoff of 50 AEU than in females. This sensitivity was confirmed in patients with nonassessable or negative cytology. In women, morphological and immunocytochemical determinations using a human telomerase reverse transcriptase monoclonal antibody (anti-hTERT recently developed in our laboratory showed a large fraction of immunoreactive inflammatory or nonbladder cells, which may justify the false-positive TRAP results. In conclusion, this assay represents an important noninvasive diagnostic tool to detect bladder cancer also in patients with negative or nonassessable urine cytology and with low-grade and early-stage lesions.

  8. Noise power associated with decreased task-induced variability of brain electrical activity in schizophrenia.

    Science.gov (United States)

    Molina, Vicente; Bachiller, Alejandro; Suazo, Vanessa; Lubeiro, Alba; Poza, Jesús; Hornero, Roberto

    2016-02-01

    In schizophrenia, both increased baseline metabolic and electroencephalographic (EEG) activities as well as decreased task-related modulation of neural dynamics have been reported. Noise power (NP) can measure the background EEG activity during task performance, and Shannon entropy (SE) is useful for quantifying the global modulation of EEG activity with a high temporal resolution. In this study, we have assessed the possible relationship between increased NP in theta and gamma bands and decreased SE modulation in 24 patients with schizophrenia and 26 controls over the parietal and central regions during a P300 task. SE modulation was calculated as the change from baseline to the active epoch (i.e., 150-550 ms following the target stimulus onset). Patients with schizophrenia displayed statistically significant higher NP values and lower SE modulation than healthy controls. We found a significant association between gamma NP and SE in all of the participants. Specifically, a NP increase in the gamma band was followed by a decrease in SE change. These results support the notion that an excess of gamma activity, unlocked to the task being performed, is accompanied by a decreased modulation of EEG activity in schizophrenia.

  9. Prenatal protein malnutrition decreases KCNJ3 and 2DG activity in rat prefrontal cortex.

    Science.gov (United States)

    Amaral, A C; Jakovcevski, M; McGaughy, J A; Calderwood, S K; Mokler, D J; Rushmore, R J; Galler, J R; Akbarian, S A; Rosene, D L

    2015-02-12

    Prenatal protein malnutrition (PPM) in rats causes enduring changes in brain and behavior including increased cognitive rigidity and decreased inhibitory control. A preliminary gene microarray screen of PPM rat prefrontal cortex (PFC) identified alterations in KCNJ3 (GIRK1/Kir3.1), a gene important for regulating neuronal excitability. Follow-up with polymerase chain reaction and Western blot showed decreased KCNJ3 expression in the PFC, but not hippocampus or brainstem. To verify localization of the effect to the PFC, baseline regional brain activity was assessed with (14)C-2-deoxyglucose. Results showed decreased activation in the PFC but not hippocampus. Together these findings point to the unique vulnerability of the PFC to the nutritional insult during early brain development, with enduring effects in adulthood on KCNJ3 expression and baseline metabolic activity. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  10. Sub-chronic exposure to methylmercury at low levels decreases butyrylcholinesterase activity in rats.

    Science.gov (United States)

    Valentini, Juliana; Vicentini, Juliana; Grotto, Denise; Tonello, Raquel; Garcia, Solange C; Barbosa, Fernando

    2010-02-01

    In this study, we examined the effects of low levels and sub-chronic exposure to methylmercury (MeHg) on butyrylcholinesterase (BuChE) activity in rats. Moreover, we examined the relationship between BuChE activity and oxidative stress biomarkers [delta-aminolevulinic acid dehydratase (delta-ALA-D) and malondialdehyde levels (MDA)] in the same animals. Rats were separated into three groups (eight animals per group): (Group I) received water by gavage; (Group II) received MeHg (30 microg/kg/day) by gavage; (Group III) received MeHg (100 microg/kg/day). The time of exposure was 90 days. BuChE and ALA-D activities were measured in serum and blood, respectively; whereas MDA levels were measured in plasma. We found BuChE and ALA-D activities decreased in groups II and III compared to the control group. Moreover, we found an interesting negative correlation between plasmatic BuChE activity and MDA (r = -0.85; p < 0.01) and a positive correlation between plasmatic BuChE activity and ALA-D activities (r = 0.78; p < 0.01), thus suggesting a possible relationship between oxidative damage promoted by MeHg exposure and the decrease of BuChE activity. In conclusion, long-term exposure to low doses of MeHg decreases plasmatic BuChE activity. Moreover, the decrease in the enzyme is strongly correlated with the oxidative stress promoted by the metal exposure. This preliminary finding highlights a possible mechanism for MeHg to reduce BuChE activity in plasma. Additionally, this enzyme could be an auxiliary biomarker on the evaluation of MeHg exposure.

  11. Telomerase: a target for therapeutic effects of curcumin and a curcumin derivative in Aβ1-42 insult in vitro.

    Directory of Open Access Journals (Sweden)

    Zijian Xiao

    Full Text Available This study was designed to investigate whether telomerase was involved in the neuroprotective effect of curcumin and Cur1. Alzheimer's disease is a consequence of an imbalance between the generation and clearance of amyloid-beta peptide in the brain. In this study, we used Aβ1-42 (10 µg/ml to establish a damaged cell model, and curcumin and Cur1 were used in treatment groups. We measured cell survival and cell growth, intracellular oxidative stress and hTERT expression. After RNA interference, the effects of curcumin and Cur1 on cells were verified. Exposure to Aβ1-42 resulted in significant oxidative stress and cell toxicity, and the expression of hTERT was significantly decreased. Curcumin and Cur1 both protected SK-N-SH cells from Aβ1-42 and up-regulated the expression of hTERT. Furthermore, Cur1 demonstrated stronger protective effects than curcumin. However, when telomerase was inhibited by TERT siRNA, the neuroprotection by curcumin and Cur1 were ceased. Our study indicated that the neuroprotective effects of curcumin and Cur1 depend on telomerase, and thus telomerase may be a target for therapeutic effects of curcumin and Cur1.

  12. Decreased salivary sulphotransferase activity correlated with inflammation and autoimmunity parameters in Sjogren's syndrome patients.

    Science.gov (United States)

    Castro, Isabel; Aguilera, Sergio; Brockhausen, Inka; Alliende, Cecilia; Quest, Andrew F G; Molina, Claudio; Urzúa, Ulises; Mandel, Ulla; Bahamondes, Verónica; Barrera, María-José; Sánchez, Marianela; González, Sergio; Hermoso, Marcela; Leyton, Cecilia; González, María-Julieta

    2012-03-01

    To determine the expression and enzymatic activities of sulphotransferases involved in mucin hyposulphation in labial salivary glands (LSGs) from SS patients and to correlate sulphotransferase activity with clinical parameters such as secretion, inflammation and serology. LSG from 31 SS patients and 31 control subjects were studied. Relative mRNA and protein levels of Gal3-O-sulphotransferases (Gal3STs) and β1,3-galactosyltransferase-5 (β3GalT5) were determined by quantitative RT-PCR and western blotting, respectively. Enzymatic activities were quantified using radioactively labelled donor substrates and specific acceptor substrates. Products were purified by chromatography. Spearman's correlation analysis was used to compare data. The levels of Gal3ST activity were significantly decreased in SS patients, without changes in mRNA and protein levels, while the enzymatic activities of glycosyltransferases involved in mucin glycosylation were similar in both groups. An inverse correlation was observed between Gal3ST activity and glandular function measured by scintigraphy, but not with unstimulated salivary flow. Gal3ST activity was inversely correlated with focus score, TNF-α levels and presence of the autoantibodies Ro/SS-A and La/SS-B. The decrease in sulphotransferase activity provides an explanation for mucin hyposulphation observed in the LSGs from SS patients. The decrease in Gal3STs activity was not a consequence of reduced gene expression, but probably due to alterations in the enzyme activity regulation. Interestingly, the levels of sulphotransferase activity detected correlated well with secretory function, inflammation and serology. Finally, we postulate that pro-inflammatory cytokines induced by autoantibodies, such as Ro/SS-A and La/SS-B in SS patients, may modulate Gal3ST activity, thereby altering mucin quality and leading to mouth dryness.

  13. Reward prediction-related increases and decreases in tonic neuronal activity of the pedunculopontine tegmental nucleus

    Directory of Open Access Journals (Sweden)

    Ken-Ichi eOkada

    2013-05-01

    Full Text Available The neuromodulators serotonin, acetylcholine, and dopamine have been proposed to play important roles in the execution of movement, control of several forms of attentional behavior, and reinforcement learning. While the response pattern of midbrain dopaminergic neurons and its specific role in reinforcement learning have been revealed, the roles of the other neuromodulators remain elusive. Reportedly, neurons in the dorsal raphe nucleus, one major source of serotonin, continually track the state of expectation of future rewards by showing a correlated response to the start of a behavioral task, reward cue presentation, and reward delivery. Here, we show that neurons in the pedunculopontine tegmental nucleus (PPTN, one major source of acetylcholine, showed similar encoding of the expectation of future rewards by a systematic increase or decrease in tonic activity. We recorded and analyzed PPTN neuronal activity in monkeys during a reward conditioned visually guided saccade task. The firing patterns of many PPTN neurons were tonically increased or decreased throughout the task period. The tonic activity pattern of neurons was correlated with their encoding of the predicted reward value; neurons exhibiting an increase or decrease in tonic activity showed higher or lower activity in the large reward-predicted trials, respectively. Tonic activity and reward-related modulation ended around the time of reward delivery. Additionally, some tonic changes in activity started prior to the appearance of the initial stimulus, and were related to the anticipatory fixational behavior. A partially overlapping population of neurons showed both the initial anticipatory response and subsequent predicted reward value-dependent activity modulation by their systematic increase or decrease of tonic activity. These bi-directional reward- and anticipatory behavior-related modulation patterns are suitable for the presumed role of the PPTN in reward processing and

  14. Peroxynitrite induced decrease in Na+, K+-ATPase activity is restored by taurine

    Institute of Scientific and Technical Information of China (English)

    Necla Kocak-Toker; Murat Giris; Feti Tülübas; Müjdat Uysal; Gülcin Aykac-Toker

    2005-01-01

    AIM: Peroxynitrite (ONOO-) is a powerful oxidant shown to damage membranes. In the present study, the effect of taurine on changes of liver plasma membrane Na+, K+-ATPase induced by ONOO- was investigated. METHODS: Liver plasma membrane was exposed toONOO-with or without taurine. Na+, K+-ATPase activity and lipid peroxidation as thiobarbituric acid reactive substances (TBARS) levels were measured.RESULTS: Different concentrations of ONOO- (100, 200,500, and 1 000 μmol/L) were found to decrease liver plasma membrane Na+, K+-ATPase activity significantly. The depletion of enzyme activity was not concentration dependent. Effects of different concentrations of taurine on liver plasma membrane Na+, K+-ATPase activity were also measured. Taurine did not cause any increase in enzyme activity. When plasma membranes were treated with 200 μmol/L ONOO- with different concentrations of taurine, a restoring effect of taurine on enzyme activity was observed. TBARS levels were also measured and taurine was found to decrease the elevated values. CONCLUSION: Taurine is observed to act as an antioxidant of ONOO-to decrease lipid peroxidation and thus affect liver plasma membrane Na+, K+-ATPase by restoring its activity.

  15. Antiproliferative Effects of Cucurbitacin B in Breast Cancer Cells: Down-Regulation of the c-Myc/hTERT/Telomerase Pathway and Obstruction of the Cell Cycle

    Directory of Open Access Journals (Sweden)

    Suwit Duangmano

    2010-12-01

    Full Text Available Naturally occurring cucurbitacins have been shown to have anticancer, antimicrobial and anti-inflammatory activities. In this study, we determined the effects of cucurbitacin B extracted from the Thai herb Trichosanthes cucumerina L. on telomerase regulation in three human breast cancer cell lines (T47D, SKBR-3, and MCF-7 and a mammary epithelium cell line (HBL-100. Cell viability after treatment with cucurbitacin B, which is an active ingredient of this herb, was assessed. Telomeric Repeat Amplification Protocol (TRAP assays and RT-PCR (qualitative and realtime were performed to investigate activity of telomerase as well as expression of human telomerase reverse transcriptase (hTERT and c-Myc. The c-Myc protein level was also determined in SKBR-3 and HBL-100 cells. Our results show that the cucurbitacin B inhibits growth and telomerase activity in the three breast cancer cell lines and exerts an obvious inhibitory effect in the estrogen receptor (ER-negative breast cancer SKBR-3 cells. The expression of hTERT and c-Myc were also inhibited by cucurbitacin B, In addition, a clear reduction of c-Myc protein was observed after treatment in SKBR-3 cells even with a concentration of cucurbitacin B that was ten-times lower compared to the concentration used for HBL-100. Our findings imply that cucurbitacin B exerts an anticancer effect by inhibiting telomerase via down regulating both the hTERT and c-Myc expression in breast cancer cells.

  16. Decrease of epidermal histidase activity by tumor-promoting phorbol esters.

    Science.gov (United States)

    Colburn, N H; Lau, S; Head, R

    1975-11-01

    The potent skin tumor promoter (12-O-tetradecanoyl phorbol-13-acetate (TPA) stimulates epidermal macromolecular synthesis as well as proliferation, but little is known of specific functional aberrations produced by TPA. This report presents results of a study on the effects of TPA on epidermal histidase (L-histidine ammonia lyase), an enzyme found in normal epidermis but not in dermis or in mouse squamous cell carcinomas. Histidase activity was assayed on postmitochondrial supernatants obtained from hairless mouse epidermis after removal by keratotome. Topical TPA treatment at doses active in tumor promotion (1.7 to 17.0 nmoles/application) produced dose-dependent decreases in epidermal histidase specific activity at 19 hr posttreatment. The onset of the decrease occurred at 12 hr with recovery to control level specific activity by 5 days, showing kinetics similar to those obtained for stimulation of DNA synthesis. This decrease in histidase could not be attributed to a general inhibition of soluble protein synthesis or to the appearance of an inhibitor of histidase activity. The strong promoter TPA produced a greater histidase decrease than did the moderate promoter and mitogen 12,13-didecanoyl phorbol at equimolar dose, while phorbol, a nonpromoter and nonmitogen, produced no effects on histidase. The relationship of this histidase depression to tumor promotion and not initiation is further indicated by the finding that (a) Tween 60, a structurally unrelated tumor promotor, also produced a decrease in histidase; and (b) the tumor initiator urethan and an initiating dose of 9,10-dimethybenz(a)anthracene showed no effects on histadase activity.

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

    Science.gov (United States)

    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, compared to four repeats, showed much greater dynamics and accessibility to telomerase binding and activity, and loading of the ALT-associated proteins RAD51, WRN and BLM. Although the eight repeats are highly dynamic, they can fold into two GQs, which limited protein accessibility. In contrast, the telomere-specific protein, POT1 is unique in that it binds independently of repeat number. Our results suggest that the telomeric overhang length and dynamics may contribute to the regulation of telomere extension via telomerase action and the ALT mechanism. PMID:24836024

  18. NBS1 plays a synergistic role with telomerase in the maintenance of telomeres in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Najdekrova Lucie

    2012-09-01

    Full Text Available Abstract Background Telomeres, as elaborate nucleo-protein complexes, ensure chromosomal stability. When impaired, the ends of linear chromosomes can be recognised by cellular repair mechanisms as double-strand DNA breaks and can be healed by non-homologous-end-joining activities to produce dicentric chromosomes. During cell divisions, particularly during anaphase, dicentrics can break, thus producing naked chromosome tips susceptible to additional unwanted chromosome fusion. Many telomere-building protein complexes are associated with telomeres to ensure their proper capping function. It has been found however, that a number of repair complexes also contribute to telomere stability. Results We used Arabidopsis thaliana to study the possible functions of the DNA repair subunit, NBS1, in telomere homeostasis using knockout nbs1 mutants. The results showed that although NBS1-deficient plants were viable, lacked any sign of developmental aberration and produced fertile seeds through many generations upon self-fertilisation, plants also missing the functional telomerase (double mutants, rapidly, within three generations, displayed severe developmental defects. Cytogenetic inspection of cycling somatic cells revealed a very early onset of massive genome instability. Molecular methods used for examining the length of telomeres in double homozygous mutants detected much faster telomere shortening than in plants deficient in telomerase gene alone. Conclusions Our findings suggest that NBS1 acts in concert with telomerase and plays a profound role in plant telomere renewal.

  19. The effects of telomerase inhibition on prostate tumor-initiating cells.

    Science.gov (United States)

    Marian, Calin O; Wright, Woodring E; Shay, Jerry W

    2010-07-15

    Prostate cancer is the most common malignancy in men, and patients with metastatic disease have poor outcome even with the most advanced therapeutic approaches. Most cancer therapies target the bulk tumor cells, but may leave intact a small population of tumor-initiating cells (TICs), which are believed to be responsible for the subsequent relapse and metastasis. Using specific surface markers (CD44, integrin alpha(2)beta(1) and CD133), Hoechst 33342 dye exclusion, and holoclone formation, we isolated TICs from a panel of prostate cancer cell lines (DU145, C4-2 and LNCaP). We have found that prostate TICs have significant telomerase activity which is inhibited by imetelstat sodium (GRN163L), a new telomerase antagonist that is currently in Phase I/II clinical trials for several hematological and solid tumor malignancies. Prostate TICs telomeres were of similar average length to the telomeres of the main population of cells and significant telomere shortening was detected in prostate TICs as a result of imetelstat treatment. These findings suggest that telomerase inhibition therapy may be able to efficiently target the prostate TICs in addition to the bulk tumor cells, providing new opportunities for combination therapies.

  20. Iron Deficiency Decreases the Fe(III)-Chelate Reducing Activity of Leaf Protoplasts1

    Science.gov (United States)

    González-Vallejo, Elena B.; Morales, Fermín; Cistué, Luis; Abadía, Anunciación; Abadía, Javier

    2000-01-01

    The ferric-chelate reductase (FC-R) activity of mesophyll protoplasts isolated from Fe-sufficient (control) and Fe-deficient sugar beet (Beta vulgaris L.) leaves has been characterized. Measurements were made in an ionic environment similar to that in the apoplastic space of the sugar beet mesophyll cells. The FC-R activity of Fe-sufficient and Fe-deficient protoplasts was dependent on light. Fe deficiency decreased markedly the FC-R activity per protoplast surface unit. The optimal pH for the activity of the FC-R in mesophyll protoplasts was in the range 5.5 to 6.0, typical of the apoplastic space. Beyond pH 6.0, the activity of the FC-R in mesophyll protoplasts decreased markedly in both Fe-sufficient and Fe-deficient protoplasts. These data suggest that both the intrinsic decrease in FC-R activity per protoplast surface and a possible shift in the pH of the apoplastic space could lead to the accumulation of physiologically inactive Fe pools in chlorotic leaves. PMID:10677427

  1. Decrease in catalase activity of Folsomia candida fed a Bt rice diet

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Yiyang, E-mail: yuanyy@ioz.ac.cn [State Key Laboratory of Integrated Management of Pest and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101 (China); Graduate School, Chinese Academy of Sciences, Beijing 100039 (China); Ke Xin, E-mail: xinke@sibs.ac.cn [Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032 (China); Chen Fajun, E-mail: fajunchen@njau.edu.cn [College of Plant Protection, Department of Entomology, Nanjing Agricultural University, Nanjing 210095 (China); Krogh, Paul Henning, E-mail: phk@dmu.dk [Department of Bioscience, University of Aarhus, P.O. Box 314, Vejlsoevej 25, DK-8600 Silkeborg (Denmark); Ge Feng, E-mail: gef@ioz.ac.cn [State Key Laboratory of Integrated Management of Pest and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101 (China)

    2011-12-15

    Here we report the effects of three Bt-rice varieties and their non-Bt conventional isolines on biological traits including survival, reproduction, and the activities of three antioxidant enzymes superoxide dismutase, catalase and peroxidase, in the Collembolan, Folsomia candida. The reproduction was significantly lower when fed Kemingdao and Huahui1 than those feeding on their non-GM near-isogenic varieties Xiushui and Minghui63 respectively, this can be explained by the differences of plant compositions depended on variety of rice. The catalase activity of F. candida was significantly lower when fed the Bt-rice variety Kemingdao compared to the near-isogenic non-Bt-rice variety Xiushui. This suggests that some Bt-rice varieties may impose environmental stress to collembolans. We emphasize that changes in activity of antioxidant enzymes of non-target organisms are important in understanding the ecological consequences for organisms inhabiting transgenic Bt-rice plantations. - Highlights: > We examine the effects of Bt-rice on Folsomia candida with laboratory test. > The reproduction of F. candida was decreased by two Bt-rice varieties. > Decreased reproduction caused by the differences of varieties or C/N ratio of rice. > The catalase activity was decreased by Bt-rice Kemingdao. > Some Bt-rice may impose environmental stress on NTOs. - The catalase of the collembolan (Folsomia candida) was decreased when fed Bt-rice, Kemingdao.

  2. The cell-free fetal DNA fraction in maternal blood decreases after physical activity

    DEFF Research Database (Denmark)

    Schlütter, Jacob Mørup; Hatt, Lotte; Bach, Cathrine;

    2014-01-01

    of cycling with a pulse-rate of 150 beats per minute. The concentrations of cffDNA (DYS14) and cfDNA (RASSF1A) were assessed using quantitative real-time polymerase chain reaction. RESULTS: The fetal fraction decreased significantly in all participants after physical activity (p 

  3. Decreased peripheral natural killer cells activity in the immune activated stage of chronic hepatitis B.

    Directory of Open Access Journals (Sweden)

    Yuan Li

    Full Text Available BACKGROUND & AIMS: The natural course of chronic hepatitis B virus (HBV infection is characterized by different immune responses, ranging from immune tolerant (IT to immune activated (IA stages. In our study, we investigated the natural killer (NK cells activity in patients at different immunological stages of chronic HBV infection. METHODS: Blood samples obtained from 57 HBeAg positive patients with chronic hepatitis B (CHB, including 15 patients in the immune tolerant (IT stage, 42 patients in the immune activated (IA stage, and 18 healthy individuals (HI. The analyses included flow cytometry to detect NK cells, the determination of cytokine levels as well as of surface receptor expression and cytotoxicity. RESULTS: NK cells in peripheral blood were significantly lower in patients in the IA stage of CHB compared to HI (p<0.05. Patients in the IA stage of CHB had lower levels of NK cells activating receptor NKp30 and NKG2D expression, cytokine interferon-γ (IFN-γ and tumor necrosis factor-α (TNF-α production, as compared to patients in the IT stage and HI, respectively (p<0.05. Cytotoxicity of NK cells was lower in patients in the IA stage of CHB compared to patients in the IT stage and HI, respectively (p<0.05. The level of IFN-γ but not level of TNF-α and cytotoxicity of NK cells was inversely correlated with serum HBV load in patients with CHB. Peripheral NK cells activity did not correlate with ALT level. CONCLUSION: NK cells activity was lower in CHB patients, especially in those in the IA stage.

  4. Decreased activation of subcortical brain areas in the motor fatigue state: an fMRI study

    Directory of Open Access Journals (Sweden)

    Lijuan Hou

    2016-08-01

    Full Text Available One aspect of motor fatigue is the exercise-induced reduction of neural activity to voluntarily drive the muscle or muscle group. Functional magnetic resonance imaging provides access to investigate the neural activation on the whole brain level and studies observed changes of activation intensity after exercise-induced motor fatigue in the sensorimotor cortex. However, in human, little evidence exists to demonstrate the role of subcortical brain regions in motor fatigue, which is contradict to abundant researches in rodent indicating that during simple movement, the activity of the basal ganglia is modulated by the state of motor fatigue. Thus, in present study, we explored the effect of motor fatigue on subcortical areas in human. A series of fMRI data were collected from 11 healthy subjects while they were executing simple motor tasks in two conditions: before and under the motor fatigue state. The results showed that in both conditions, movements evoked activation volumes in the sensorimotor areas, SMA, cerebellum, thalamus and basal ganglia. Of primary importance are the results that the intensity and size of activation volumes in the subcortical areas (i.e. thalamus and basal ganglia areas are significantly decreased during the motor fatigue state, implying that motor fatigue disturbs the motor control processing in a way that both sensorimotor areas and subcortical brain areas are less active. Further study is needed to clarify how subcortical areas contribute to the overall decreased activity of CNS during motor fatigue state.

  5. Mean platelet volume is decreased in adults with active lupus disease

    Directory of Open Access Journals (Sweden)

    Guillermo Delgado-García

    Full Text Available ABSTRACT Background: Only a few biomarkers are available for assessing disease activity in systemic lupus erythematosus (SLE. Mean platelet volume (MPV has been recently studied as an inflammatory biomarker. It is currently unclear whether MPV may also play a role as a biomarker of disease activity in adult patients with SLE. Objective: We investigated the association between MPV and disease activity in adult patients with SLE. Methods: In this retrospective study, we compared two groups of adult patients divided according to disease activity (36 per group. Subjects were age- and gender-matched. Results: MPV was significantly decreased with respect to those of inactive patients (7.16 ± 1.39 vs. 8.16 ± 1.50, p = 0.005. At a cutoff level of 8.32 fL, MPV has a sensitivity of 86% and a specificity of 41% for the detection of disease activity. A modest positive correlation was found between MPV and albumin (r = 0.407, p = 0.001, which in turn is inversely associated with disease activity. Conclusions: In summary, MPV is decreased in adult patients with active lupus disease, and positively correlated with albumin, another biomarker of disease activity. Prospective studies are needed to evaluate the prognostic value of this biomarker.

  6. Telomerase promoter mutations in cancer: an emerging molecular biomarker?

    Science.gov (United States)

    Vinagre, João; Pinto, Vasco; Celestino, Ricardo; Reis, Marta; Pópulo, Helena; Boaventura, Paula; Melo, Miguel; Catarino, Telmo; Lima, Jorge; Lopes, José Manuel; Máximo, Valdemar; Sobrinho-Simões, Manuel; Soares, Paula

    2014-08-01

    Cell immortalization has been considered for a long time as a classic hallmark of cancer cells. Besides telomerase reactivation, such immortalization could be due to telomere maintenance through the "alternative mechanism of telomere lengthening" (ALT) but the mechanisms underlying both forms of reactivation remained elusive. Mutations in the coding region of telomerase gene are very rare in the cancer setting, despite being associated with some degenerative diseases. Recently, mutations in telomerase (TERT) gene promoter were found in sporadic and familial melanoma and subsequently in several cancer models, notably in gliomas, thyroid cancer and bladder cancer. The importance of these findings has been reinforced by the association of TERT mutations in some cancer types with tumour aggressiveness and patient survival. In the first part of this review, we summarize the data on the biology of telomeres and telomerase, available methodological approaches and non-neoplastic diseases associated with telomere dysfunction. In the second part, we review the information on telomerase expression and genetic alterations in the most relevant types of cancer (skin, thyroid, bladder and central nervous system) on record, and discuss the value of telomerase as a new biomarker with impact on the prognosis and survival of the patients and as a putative therapeutic target.

  7. MIF-1 (Pro-Leu-Gly-NH2) decreases activity in Siamese fighting fish (Betta splendens).

    Science.gov (United States)

    Brown, M M; Sardenga, P B; Olson, G A; Delatte, S W; Olson, R D

    1984-04-01

    The effects of MIF-1 (Pro-Leu-Gly-NH2) on activity and aggression of male Siamese Fighting Fish ( Betta splendens) were considered. Animals were given intraperitoneal injections of 0.0 or 10.0 mg/kg MIF-1. After a 10-minute delay, they were placed in a 10 gallon aquarium and their activity was monitored for 60 minutes. Although aggressive responses in the presence of suitable opponents were not reliably affected, as significant decrease in general activity was produced. This is compatible with differential effects of MIF-1 across species.

  8. Human telomerase reverse transcriptase binds to a pre-organized hTR in vivo exposing its template.

    Science.gov (United States)

    Zemora, Georgeta; Handl, Stefan; Waldsich, Christina

    2016-01-08

    Telomerase is a specialized reverse transcriptase that is responsible for telomere length maintenance. As in other organisms, the minimal components required for an active human telomerase are the template-providing telomerase RNA (hTR) and the enzymatic entity telomerase reverse transcriptase (hTERT). Here, we explored the structure of hTR and the hTERT-induced conformational changes within hTR in living cells. By employing an in vivo DMS chemical probing technique, we showed that the pseudoknot and associated triple helical scaffold form stably in vivo independently of hTERT. In fact, the dimethyl-sulfate (DMS) modification pattern suggests that hTR alone is capable of adopting a conformation that is suited to interact with hTERT. However, in the absence of hTERT the template region of hTR is only weakly accessible to DMS-modifications. The predominant change after binding of hTERT to hTR is the exposure of the template region.

  9. Dioxin exerts anti-estrogenic actions in a novel dioxin-responsive telomerase-immortalized epithelial cell line of the porcine oviduct (TERT-OPEC).

    Science.gov (United States)

    Hombach-Klonisch, Sabine; Pocar, Paola; Kauffold, Johannes; Klonisch, Thomas

    2006-04-01

    Oviduct epithelial cells are important for the nourishment and survival of ovulated oocytes and early embryos, and they respond to the steroid hormones estrogen and progesterone. Endocrine-disrupting polyhalogenated aromatic hydrocarbons (PHAH) are environmental toxins that act in part through the ligand-activated transcription factor arylhydrocarbon receptor (AhR; dioxin receptor), and exposure to PHAH has been shown to decrease fertility. To investigate effects of PHAHs on the oviduct epithelium as a potential target tissue of dioxin-type endocrine disruptors, we have established a novel telomerase-immortalized oviduct porcine epithelial cell line (TERT-OPEC). TERT-OPEC exhibited active telomerase and the immunoreactive epithelial marker cytokeratin but lacked the stromal marker vimentin. TERT-OPEC contained functional estrogen receptor (ER)-alpha and AhR, as determined by the detection of ER-alpha- and AhR-specific target molecules. Treatment of TERT-OPEC with the AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) resulted in a significant increase in the production of the cytochrome P-450 microsomal enzyme CYP1A1. Activated AhR caused a downregulation of ER nuclear protein fraction and significantly decreased ER-signaling in TERT-OPEC as determined by ERE-luciferase transient transfection assays. In summary, the TCDD-induced and AhR-mediated anti-estrogenic responses by TERT-OPEC suggest that PHAH affect the predominantly estrogen-dependent differentiation of the oviduct epithelium within the fallopian tube. This action then alters the local endocrine milieu, potentially resulting in a largely unexplored cause of impaired embryonic development and female infertility.

  10. Comparison between effects of free curcumin and curcumin loaded NIPAAm-MAA nanoparticles on telomerase and PinX1 gene expression in lung cancer cells.

    Science.gov (United States)

    Badrzadeh, Fariba; Akbarzadeh, Abolfazl; Zarghami, Nosratollah; Yamchi, Mohammad Rahmati; Zeighamian, Vahide; Tabatabae, Fateme Sadate; Taheri, Morteza; Kafil, Hossein Samadi

    2014-01-01

    Herbal compounds such as curcumin which decrease telomerase and gene expression have been considered as beneficial tools for lung cancer treatment. In this article, we compared the effects of pure curcumin and curcumin-loaded NIPAAm-MAA nanoparticles on telomerase and PinX1 gene expression in a lung cancer cell line. A tetrazolium-based assay was used for determination of cytotoxic effects of curcumin on the Calu-6 lung cancer cell line and telomerase and pinX1 gene expression was measured with real-time PCR. MTT assay showed that Curcumin-loaded NIPAAm-MAA inhibited the growth of the Calu-6 lung cancer cell line in a time and dose-dependent manner. Our q-PCR results showed that the expression of telomerase gene was effectively reduced as the concentration of curcumin-loaded NIPAAm-MAA increased while expression of the PinX1 gene became elevated. The results showed that curcumin- loaded- NIPAAm-MAA exerted cytotoxic effects on the Calu-6 cell line through down-regulation of telomerase and stimulation of pinX1 gene expression. NIPPAm-MAA could be good carrier for such kinds of hydrophobic agent.

  11. Decreased electrophysiological activity represents the conscious state of emptiness in meditation.

    Science.gov (United States)

    Hinterberger, Thilo; Schmidt, Stephanie; Kamei, Tsutomu; Walach, Harald

    2014-01-01

    Many neuroscientific theories explain consciousness with higher order information processing corresponding to an activation of specific brain areas and processes. In contrast, most forms of meditation ask for a down-regulation of certain mental processing activities while remaining fully conscious. To identify the physiological properties of conscious states with decreased mental and cognitive processing, the electrical brain activity (64 channels of EEG) of 50 participants of various meditation proficiencies was measured during distinct and idiosyncratic meditative tasks. The tasks comprised a wakeful "thoughtless emptiness (TE)," a "focused attention," and an "open monitoring" task asking for mindful presence in the moment and in the environment without attachment to distracting thoughts. Our analysis mainly focused on 30 highly experienced meditators with at least 5 years and 1000 h of meditation experience. Spectral EEG power comparisons of the TE state with the resting state or other forms of meditation showed decreased activities in specific frequency bands. In contrast to a focused attention task the TE task showed significant central and parietal gamma decreases (p waves than a wakeful closed eyes resting condition. A group of participants with none or little meditation practice did not present those differences significantly. Our findings indicate that a conscious state of TE reached by experienced meditators is characterized by reduced high-frequency brain processing with simultaneous reduction of the low frequencies. This suggests that such a state of meditative conscious awareness might be different from higher cognitive and mentally focused states but also from states of sleep and drowsiness.

  12. Decreased Electrophysiological Activity Represents the Conscious State of Emptiness in Meditation

    Directory of Open Access Journals (Sweden)

    Thilo eHinterberger

    2014-02-01

    Full Text Available Many neuroscientific theories explain consciousness with higher order information processing corresponding to an activation of specific brain areas and processes. In contrast, most forms of meditation ask for a down-regulation of certain mental processing activities while remaining fully conscious. To identify the physiological properties of conscious states with decreased mental and cognitive processing, the electrical brain activity (64 channels of EEG of 50 participants of various meditation proficiencies was measured during distinct and idiosyncratic meditative tasks. The tasks comprised a wakeful ‘thoughtless emptiness (TE’, a ‘focused attention’, and an ‘open monitoring’ task asking for mindful presence in the moment and in the environment without attachment to distracting thoughts. Our analysis mainly focused on 30 highly experienced meditators with at least 5 years and 1000 hours of meditation experience.Spectral EEG power comparisons of the TE state with the resting state or other forms of meditation showed decreased activities in specific frequency bands. In contrast to a focused attention task the TE task showed significant central and parietal gamma decreases (pOur findings indicate that a conscious state of thoughtless emptiness reached by experienced meditators is characterized by reduced high-frequency brain processing with simultaneous reduction of the low frequencies. This suggests that such a state of meditative conscious awareness might be different from higher cognitive and mentally focused states but also from states of sleep and drowsiness.

  13. Decreased basal ganglia activation in subjects with chronic fatigue syndrome: association with symptoms of fatigue.

    Directory of Open Access Journals (Sweden)

    Andrew H Miller

    Full Text Available Reduced basal ganglia function has been associated with fatigue in neurologic disorders, as well as in patients exposed to chronic immune stimulation. Patients with chronic fatigue syndrome (CFS have been shown to exhibit symptoms suggestive of decreased basal ganglia function including psychomotor slowing, which in turn was correlated with fatigue. In addition, CFS patients have been found to exhibit increased markers of immune activation. In order to directly test the hypothesis of decreased basal ganglia function in CFS, we used functional magnetic resonance imaging to examine neural activation in the basal ganglia to a reward-processing (monetary gambling task in a community sample of 59 male and female subjects, including 18 patients diagnosed with CFS according to 1994 CDC criteria and 41 non-fatigued healthy controls. For each subject, the average effect of winning vs. losing during the gambling task in regions of interest (ROI corresponding to the caudate nucleus, putamen, and globus pallidus was extracted for group comparisons and correlational analyses. Compared to non-fatigued controls, patients with CFS exhibited significantly decreased activation in the right caudate (p = 0.01 and right globus pallidus (p = 0.02. Decreased activation in the right globus pallidus was significantly correlated with increased mental fatigue (r2 = 0.49, p = 0.001, general fatigue (r2 = 0.34, p = 0.01 and reduced activity (r2 = 0.29, p = 0.02 as measured by the Multidimensional Fatigue Inventory. No such relationships were found in control subjects. These data suggest that symptoms of fatigue in CFS subjects were associated with reduced responsivity of the basal ganglia, possibly involving the disruption of projections from the globus pallidus to thalamic and cortical networks.

  14. Soluble CD206 plasma levels in rheumatoid arthritis reflect decrease in disease activity

    DEFF Research Database (Denmark)

    Heftdal, Line Dam; Stengaard-Pedersen, Kristian; Ørnbjerg, Lykke Midtbøll

    2017-01-01

    and after 3, 6, 12 and 24 months. Baseline plasma level of sCD206 in treatment naïve RA patients was 0.33 mg/L (CI: 0.33-0.38 mg/L) corresponding to the upper part of the reference interval for healthy controls (0.10-0.43 mg/L). In the PLA group, sCD206 levels decreased after 3 months, but did not differ...... from baseline after 6 months. In the ADA group, however, levels remained lower than baseline throughout the treatment period. In conclusion, initially, plasma sCD206 in early RA patients decreased in accordance with disease activity and initiation of DMARD treatment. Treatment with anti-TNFα preserved...... this decrease throughout the study period....

  15. Overcrowding stress decreases macrophage activity and increases Salmonella Enteritidis invasion in broiler chickens.

    Science.gov (United States)

    Gomes, A V S; Quinteiro-Filho, W M; Ribeiro, A; Ferraz-de-Paula, V; Pinheiro, M L; Baskeville, E; Akamine, A T; Astolfi-Ferreira, C S; Ferreira, A J P; Palermo-Neto, J

    2014-01-01

    Overcrowding stress is a reality in the poultry industry. Chickens exposed to long-term stressful situations present a reduction of welfare and immunosuppression. We designed this experiment to analyse the effects from overcrowding stress of 16 birds/m(2) on performance parameters, serum corticosterone levels, the relative weight of the bursa of Fabricius, plasma IgA and IgG levels, intestinal integrity, macrophage activity and experimental Salmonella Enteritidis invasion. The results of this study indicate that overcrowding stress decreased performance parameters, induced enteritis and decreased macrophage activity and the relative bursa weight in broiler chickens. When the chickens were similarly stressed and infected with Salmonella Enteritidis, there was an increase in feed conversion and a decrease in plasma IgG levels in the stressed and Salmonella-infected birds. We observed moderate enteritis throughout the duodenum of chickens stressed and infected with Salmonella. The overcrowding stress decreased the macrophage phagocytosis intensity and increased Salmonella Enteritidis counts in the livers of birds challenged with the pathogenic bacterium. Overcrowding stress via the hypothalamic-pituitary-adrenal axis that is associated with an increase in corticosterone and enteritis might influence the quality of the intestinal immune barrier and the integrity of the small intestine. This effect allowed pathogenic bacteria to migrate through the intestinal mucosa, resulting in inflammatory infiltration and decreased nutrient absorption. The data strengthen the hypothesis that control of the welfare of chickens and avoidance of stress from overcrowding in poultry production are relevant factors for the maintenance of intestinal integrity, performance and decreased susceptibility to Salmonella infection.

  16. Sex-Dependent Decrease of Sphingomyelinase Activity During Alcohol Withdrawal Treatment

    Directory of Open Access Journals (Sweden)

    Christiane Mühle

    2014-06-01

    Full Text Available Background: In vitro and in vivo studies have demonstrated the role of the acid sphingomyelinase (ASM in pathophysiological processes and alterations in response to ethanol exposure. Cellular and plasmatic ASM activities are increased in male alcohol dependent patients and decrease during physical withdrawal. Methods: Here, we analyzed the time course of ASM in male and also female acutely intoxicated patients during alcohol withdrawal and compared the activity levels to those under long-term maintenance treatment. Craving and further psychometric parameters were assessed by questionnaires. Results: The gradual decrease of serum ASM was confirmed in males (pConclusion: These data support the potential of ASM as a biomarker for the course of withdrawal therapy in males and provide the first associations of this enzyme with psychological variables such as craving and depression.

  17. Exacerbated cardiac fibrosis induced by β-adrenergic activation in old mice due to decreased AMPK activity.

    Science.gov (United States)

    Wang, Jingjing; Song, Yao; Li, Hao; Shen, Qiang; Shen, Jing; An, Xiangbo; Wu, Jimin; Zhang, Jianshu; Wu, Yunong; Xiao, Han; Zhang, Youyi

    2016-11-01

    Senescent hearts exhibit defective responses to β-adrenergic receptor (β-AR) over-activation upon stress, leading to more severe pathological cardiac remodelling. However, the underlying mechanisms remain unclear. Here, we investigated the role of adenosine monophosphate-activated protein kinase (AMPK) in protecting against ageing-associated cardiac remodelling in mice upon β-AR over-activation. 10-week-old (young) and 18-month-old (old) mice were subcutaneously injected with the β-AR agonist isoproterenol (ISO; 5 mg/kg). More extensive cardiac fibrosis was found in old mice upon ISO exposure than in young mice. Meanwhile, ISO treatment decreased AMPK activity and increased β-arrestin 1, but not β-arrestin 2, expression, and the effects of ISO on AMPK and β-arrestin 1 were greater in old mice than in young mice. Similarly, young AMPKα2-knockout (KO) mice showed more extensive cardiac fibrosis upon ISO exposure than that was observed in age-matched wild-type (WT) littermates. The extent of cardiac fibrosis in WT old mice was similar to that in young KO mice. Additionally, AMPK activities were decreased and β-arrestin 1 expression increased in KO mice. In contrast, the AMPK activator metformin decreased β-arrestin 1 expression and attenuated cardiac fibrosis in both young and old mice upon ISO exposure. In conclusion, more severe cardiac fibrosis is induced by ISO in old mice than in young mice. A decrease in AMPK activity, which further increases β-arrestin 1 expression, is the central mechanism underlying the ageing-related cardiac fibrosis induced by ISO. The AMPK activator metformin is a promising therapeutic agent for treating ageing-related cardiac remodelling upon β-AR over-activation.

  18. Neuroprotective effects of human telomerase reverse transcriptase on beta-amyloid fragment 25-35-treated human embryonic cortical neurons

    Institute of Scientific and Technical Information of China (English)

    Lingping Kong; Lingzhi Wu; Jie Zhang; Yaping Liao; Huaqiao Wang

    2009-01-01

    activity was measured using a PCR-based telomeric repeat amplification protocol (TRAP) ELISA kit.Neural activity in human embryonic cortical neurons was examined by MTT assay;apoptosis was measured using TUNEL assay;and Cdk5 and p16 protein expressions were measured by Western blot.RESULTS:Expression of hTERT protein was significantly increased and peaked at day 3 post-transfection in the Ad-hTERT group.No hTERT expression was detected in the Ad-GFP and control groups.Telomerase activity was significantly greater in the Ad-hTERT group compared with the Ad-GFP and control groups (P<0.01).Compared with the control group,cell activity was significantly decreased (P<0.05),and cell apoptotic rate,Cdk5 and p16 expression were significantly increased (P<0.01) in the model group.Compared with the model group,cell activity was increased in the Ad-hTERT group,and peaked at day 3 post-transfection (P<0.05).Neuroprotective effects also peaked at day 3 post-transfection;and the apoptotic rate,Cdk5 and p16 expression significantly decreased (P<0.01).CONCLUSION:Expression of hTERT in human embryonic cortical neurons can relieve Aβ25-35-induced neuronal apoptosis.The possible mechanism by which hTERT produces these neuroprotective effects may be associated with inhibition of Cdk5 and p16 expression.

  19. Lead exposure is associated with decreased serum paraoxonase 1 (PON1) activity and genotypes.

    Science.gov (United States)

    Li, Wan-Fen; Pan, Mei-Hung; Chung, Meng-Chu; Ho, Chi-Kung; Chuang, Hung-Yi

    2006-08-01

    Lead exposure causes cardiac and vascular damage in experimental animals. However, there is considerable debate regarding the causal relationship between lead exposure and cardiovascular dysfunction in humans. Paraoxonase 1 (PON1), a high-density lipoprotein-associated antioxidant enzyme, is capable of hydrolyzing oxidized lipids and thus protects against atherosclerosis. Previous studies have shown that lead and several other metal ions are able to inhibit PON1 activity in vitro. To investigate whether lead exposure has influence on serum PON1 activity, we conducted a cross-sectional study of workers from a lead battery manufactory and lead recycling plant. Blood samples were analyzed for whole-blood lead levels, serum PON1 activity, and three common PON1 polymorphisms (Q192R, L55M, -108C/T). The mean blood lead level (+/-SD) of this cohort was 27.1+/-15 microg/dL. Multiple linear regression analysis showed that blood lead levels were significantly associated with decreased serum PON1 activity (p<0.001) in lead workers. This negative correlation was more evident for workers who carry the R192 allele, which has been suggested to be a risk factor for coronary heart disease. Taken together, our results suggest that the decrease in serum PON1 activity due to lead exposure may render individuals more susceptible to atherosclerosis, particularly subjects who are homozygous for the R192 allele.

  20. Decreased beta-band activity is correlated with disambiguation of hidden figures.

    Science.gov (United States)

    Minami, Tetsuto; Noritake, Yosuke; Nakauchi, Shigeki

    2014-04-01

    Insight is commonly described as sudden comprehension, sometimes called an "Aha! moment." In everyday life, we apply the process of insight to problems that are difficult to solve at first glance or that we perceive as ambiguous; however the brain dynamics underlying the disambiguation process remains elusive. Beta-band oscillatory brain activity has been hypothesized to reflect the transition of cognitive states. To elucidate the neural mechanism of insight, we recorded electroencephalograms while subjects were presented with hidden figures followed by unambiguous, gray images. We identified oscillatory activity to detect temporal changes, and compared brain activity that occurred during a perceptual transition with activity that occurred when no perceptual transition occurred. Statistical comparison confirmed stronger beta-power decrease during perceptual transition. Source analysis indicated that the beta-power decrease was around the parietal-posterior regions, mainly in the precuneus. We propose that beta-band desynchronization in the parietal-posterior regions reflects the disambiguation process, and our findings provide additional support for the theory that beta-band activity is related to the transition of cognitive state.

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

    Science.gov (United States)

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

    2011-10-01

    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) 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 against virus

  2. 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

  3. 雌二醇通过增加端粒酶活性影响人LECs生长动力学的实验研究%The regulation of estradiol on growth dynamics of human LECs affected by increasing telomerase activity

    Institute of Scientific and Technical Information of China (English)

    王杰; 康刚劲; 袁雪峰; 徐曼华; 蒋燕; 罗波

    2016-01-01

    Background Human LECs can express telomerase activity,which participates in the formation of cataract.It is reported that estrogen can increase the expression of telomerase activity in human endometrial cancer and breast cancer cells and play an important role in promoting proliferation and anti-apoptosis,but whether estrogen exerts its role on human LECs is still unclear.Objective This study aimed to investigate whether β-estradiol (β-E2) can increase the telomerase activity of human LECs and the influence of β-E2 on proliferation and apoptosis of human LECs.Method Human LECs line was cultured and passaged in vitro,and 1×10-6 mol/L β-E2 was added in the medium for 0,6,12,24 and 48 hours,and reverse transcription PCR was used to determine the optimal time of the expression of human telomerase reverse transcriptase (hTERT) mRNA in the cells.Cultured cells were divided into five groups.The cells in the blank contol group were cultured in the routin medium.Ethanol of 0.1% was added in the solvent control group,and 1 × 10-8,1 × 10-7 or 1 × 10-6 mol/L β-E2 was added in the medium in different contents of β-E2 groups,respectively.The relative expression level of hTERT mRNA in different groups was detected by reverse transcription PCR.Telomere repeat amplification protocol (TRAP)-ELISA was employed to determine the telomerase activity.The proliferative value of the cells was assayed by cell counting kit-8,and the apoptosis rate of the cells was examined by Hoechst33258 staining.Results The optimal time of β-E2 to rise the expression of hTERT mRNA (absorbance) was at 24 hours under the 1×10-6 mol/L.The relative expression levels of hTERT mRNA in the cells were 0.477±0.015,0.712±0.013 and 0.914±0.031 in the 1 ×10-8,1 ×10-7 and 1 ×10-6 mol/L β-E2 group,which were signifincatly higher than 0.428±0.010 in the blank control group and 0.426±0.010 in the solvent control group (all at P<0.05).The telomerase activity values (absorbance) were 0.711 ±0

  4. To explore the effective of telomerase activity on radiosensitivity of cervical cancer cell line tolerated to radiation%放射抗拒的宫颈癌细胞端粒酶活性对其放射敏感性影响的研究

    Institute of Scientific and Technical Information of China (English)

    陈敏; 邢丽娜

    2013-01-01

    Objective To investigate the correlation of the telomerase activity and radiosensitivity of surviving progeny from different doses irradiated cervical carcinoma cell. Methods The HeLa cells were irradited with 0,2,6,10 Gy of X -ray for three times and the surviving progeny were subculture. There were four groups: HeLa, HeLa - 2 , HeLa - 6 , HeLa - 10. The telomerase activity was measured by the polymerase chain reaction -based telomeic repeat amplification protocol coupled with ELISA. And the expression of the hTERT mRNA were detected by the RT - PCR assay. The radiosesitivity index was examined by clone formation assay. Results The HeLa cells were treated by different doses of irradiation. The telomerase activity of HeLa group HeLa - 2 group HeLa -6 group was( 1. 54 ±0. 01 ),( 1. 87 ±0. 01 ),( 2. 03 ±0. 02 )and the expression of hTERT mRNA was increased with the irradiation dose and was( 0. 44 ± 0. 03 ) ,( 0. 53 ± 0. 04 ),( 0. 74± 0. 07 ). Each parameter had significant differences among the survival progenies! P < 0. 05 ). But the HeLa - 10 group was( 1. 02 ±0. 024 )and (0.21 ±0. 02 )significantly reduced. Each group's radiosensitivity was declined with the different irradiation dose. The telomerase activity and the expression of the hTERT mRNA was negatively correlated with radiosensitivity of each groups( r = - 0. 927 , P < 0. 01: r = -0. 904 , P < 0. 01 ). Conclusion Radiosensitivity of the surviving progeny correlates with the telomerase activity and the expression of hTERT.%目的 通过检测不同剂量照射宫颈癌细胞后生长特性及端粒酶逆转录酶的表达,探讨其与放射敏感性之间的关系.方法 将同源的HeLa细胞分为四组,分别给予多次0Gy、2Gy、6Gy和10Gy的X射线照射,建立不同剂量的放射耐受模型,用TRAP-ELISA分别检测HeLa组、HeLa-2组、HeLa-6组和HeLa-10组端粒酶的活性,用RT-PCR检测其端粒酶hTERT的相对表达量,克隆形成实验检测其放射敏感参数α、β及SF2.

  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. Music Attenuated a Decrease in Parasympathetic Nervous System Activity after Exercise.

    Science.gov (United States)

    Jia, Tiantian; Ogawa, Yoshiko; Miura, Misa; Ito, Osamu; Kohzu