Regulation And Effect Of Telomerase And Telomeric Length In Stem Cells

2020 ◽  
Vol 15 ◽  
Author(s):  
Basak Celtikci ◽  
Gulnihal Kulaksiz Erkmen ◽  
Zeliha Gunnur Dikmen
Keyword(s):  
Telomere Length ◽  
Somatic Cells ◽  
Telomere Maintenance ◽  
The Other ◽  
Telomerase Reverse Transcriptase ◽  
Human Telomerase Reverse Transcriptase ◽  
Telomere Shortening ◽  
Maintenance Mechanism ◽  
Associated Diseases ◽  
Human Telomerase

: Telomeres are the protective end caps of eukaryotic chromosomes and they decide the proliferative lifespan of somatic cells, as the guardians of the cell replication. Telomere length in leucocytes reflects telomere length in other somatic cells. Leucocyte telomere length can be a biomarker of human ageing. The risk of diseases, which are associated with reduced cell proliferation and tissue degeneration, including aging or aging-associated diseases, such as dyskeratosis congenita, cardiovascular diseases, pulmonary fibrosis and aplastic anemia, are correlated with an increase in short telomeres. On the other hand, the risk of diseases, which are associated with increased proliferative growth, including major cancers, is correlated with long telomeres. In most of the cancers, a telomere maintenance mechanism during DNA replication is essential. The reactivation of the functional ribonucleoprotein holoenzyme complex [telomerase] starts the cascade from normal and premalignant somatic cells to advanced malignant cells. Telomerase is overexpressed during the development of cancer and embryonic stem cells, through controlling genome integrity, cancer formation and stemness. Cancer cells have mechanisms to maintain telomeres to avoid initiation of cellular senescence or apoptosis, and halting cell division by critically short telomeres. Modulation of the human telomerase reverse transcriptase is the ratelimiting step for the production of functional telomerase and the telomere maintenance. Human telomerase reverse transcriptase promoter promotes its gene expression only in tumor cells, but not in normal cells. Some cancers activate an alternative lengthening of telomeres maintenance mechanism via DNA recombination to unshorten their telomeres. Not only heritability but also oxidative stress, inflammation, environmental factors, and therapeutic interventions have an effect on telomere shortening, explaining the variability in telomere length across individuals. There have been a large number of publications, which correlate human diseases with progressive telomere shortening. Telomere length of an individual at birth is also important to follow up telomere shortening, and it can be used as biomarkers for healthy aging. On the other hand, understanding of cellular stress factors, which affect stem cell behavior, will be useful in regeneration or treatment in cancer and age-associated diseases. In this review, we will understand the connection between stem cell and telomere biology, cancer, and aging-associated diseases. This connection may be useful for discovering novel drug targets and improve outcomes for patients having cancer and aging-associated diseases.

scholarly journals The Regulation of ROS- and BECN1-Mediated Autophagy by Human Telomerase Reverse Transcriptase in Glioblastoma

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Xuelu Ding ◽  
Ziyang Nie ◽  
Zhaoyuan She ◽  
Xue Bai ◽  
Qiuhui Yang ◽  
...  
Keyword(s):  
Reverse Transcriptase ◽  
Telomere Maintenance ◽  
High Morbidity ◽  
Telomerase Reverse Transcriptase ◽  
Human Telomerase Reverse Transcriptase ◽  
Telomere Shortening ◽  
Targeting Therapy ◽  
Anticancer Treatment ◽  
Human Telomerase

Glioblastoma (GBM) is the most common and aggressive malignant brain tumor with high morbidity and mortality. Human telomerase reverse transcriptase (hTERT), the catalytic subunit of human telomerase, is overexpressed in most cancers including GBM. It is well known that hTERT can compensate telomere shortening to immortalize cells. However, in addition to the canonical function, hTERT has the roles beyond canonical telomere maintenance. To further understand the effects of hTERT on glioblastoma progression, we investigated the role of hTERT in regulating autophagy—a conserved pathway, by which cells deliver cellular organic material and impaired organelles to the lysosomes for degradation and recycle these cargos to produce energy under a stressful condition. Our results showed that downregulation of hTERT impaired autophagy levels by suppressing BECN1/beclin-1 and induced an increase of reactive oxygen species (ROS), which resulted in cell death ultimately. On the contrary, overexpression of BECN1 or treating cells with the antioxidant N-acetylcysteine (NAC) could restore the survival of hTERT knockdown cells. Our study will provide an additional basis of telomerase-targeting therapy for future clinical anticancer treatment.

Expression Profile and up-Regulation of Telomere-Associated Proteins In Multiple Myeloma

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4050-4050
Author(s):  
Rafael Díaz de la Guardia ◽  
Carolina Elosua ◽  
Purificación Catalina ◽  
Brian A Walker ◽  
David C Johnson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Multiple Myeloma ◽  
Telomere Length ◽  
Conflicts Of Interest ◽  
Telomerase Activity ◽  
Telomere Maintenance ◽  
Post Translational Modification ◽  
Human Telomerase Reverse Transcriptase ◽  
Immortal Cells ◽  
Human Telomerase

Abstract Abstract 4050 The role of the telomeres in the mechanisms of ageing and carcinogenesis has generated a considerable interest as a novel approach to the treatment of many cancers. Telomeres are nucleoproteins structures that protect the ends of eukaryotic chromosomes, which are particularly vulnerable due to progressive shortening in almost all dividing cells. The telomere length was observed as a critical factor in the initiation and progression of human cancers, and it is associated to chromosomal instability. Most immortal cells possess enzymatic activity of telomerase. This suggests that telomerase activity and telomere length maintenance may be required for unlimited cell proliferation, tumorigenesis, and protection, allowing the evasion of apoptosis in cancer development. The telomerase activity could also be regulated positively or negatively by post-trancriptional and/or post-translational modification of the enzyme without transcriptional up-regulation of human telomerase reverse transcriptase (hTERT) mRNA. In this work, we analyze the expression data of all genes involved in telomerase activity. Patients with monoclonal gammopathy of undetermined significance (MGUS), smoldering multiple myeloma (SMM), multiple myeloma (MM) and plasma cell leukemia (PLC) were studied through gene expression profiling analysis (Human Genome U133 Plus 2.0 arrays, Affymetrix). We identify 21 deregulated genes, implicated directly in telomere length maintenance activity in clonal plasma cells compared with normal cells (20 up-regulated and 1 down-regulated). These genes are MYC, KRAS, HSPA9, RB1 and members of the families: Small nucleolar ribonucleoproteins (H/ACA snoRNPs), A/B subfamily of ubiquitously expressed heterogeneous nuclear ribonucleoproteins (hnRNPs), and 14-3 -3 family. In conclusion, the myeloma cells acquire the telomere maintenance capability without deregulation of the human telomerase RNA gene (hTERC) and hTERT gene expression. It is an alternative lengthening of telomeres mechanism that has effect in the regulation of the BAD activity in apoptosis. The mechanism is based on preventing the partially-denatured proteins from aggregating, telomere maintenance through the correct processing and intranuclear trafficking of hTERC, telomerase reactivation and telomere stabilization, and efficient accumulation of hTERT in the nucleus. Thus, the findings of this study may help to improve telomerase-based therapy for multiple myeloma. Disclosures: No relevant conflicts of interest to declare.

Telomere Length and Human Telomerase Reverse Transcriptase Expression As Markers for Progression and Prognosis of Colorectal Carcinoma

2004 ◽  
Vol 22 (10) ◽  
pp. 1807-1814 ◽  
Author(s):  
Ralf Gertler ◽  
Robert Rosenberg ◽  
Dominik Stricker ◽  
Jan Friederichs ◽  
Axel Hoos ◽  
...  
Keyword(s):  
Colorectal Carcinoma ◽  
Reverse Transcriptase ◽  
Telomere Length ◽  
Tumor Stage ◽  
Cancer Tissue ◽  
Telomerase Reverse Transcriptase ◽  
Htert Expression ◽  
Human Telomerase Reverse Transcriptase ◽  
Adjacent Mucosa ◽  
Human Telomerase

PurposeMaintenance of telomeres through reactivation of telomerase is a prerequisite for tumors to preserve their ability to proliferate. The purpose of this study was to evaluate telomere length and human telomerase reverse transcriptase (hTERT) expression as markers for progression and prognosis of colorectal carcinoma.Patients and MethodsTelomere length and hTERT expression were analyzed in matched cancer and adjacent noncancer mucosa samples from 57 patients with R0-resected colorectal carcinoma. The median follow-up time was 76 months.ResultsTelomere length and hTERT expression correlated significantly in cancer tissues and adjacent mucosa samples (r = 0.52, P < .001; and r = 0.54, P < .001, respectively). Overall, cancer tissue had shorter telomeres than adjacent mucosa (P < .001). Only in noncancer tissue did telomere length decrease with age (r = 0.36; P < .01). Telomere length in cancer tissue was significantly correlated with tumor stage (P < .01), with longer telomeres in advanced tumors. Patients with ratios of telomere length in cancer to noncancer tissue greater than 0.90 had a significantly poorer overall survival compared with patients with smaller telomere length ratios (P < .002). In multivariate analysis, the telomere length ratio proved to be of independent prognostic value (P < .03).ConclusionTelomeres in colorectal carcinoma tissue were significantly shorter compared with adjacent normal mucosa as an indication for extensive cell proliferation. The correlation with tumor stage and patient survival suggest that hTERT-mediated telomere stabilization may be critical for progression and prognosis of colorectal carcinoma.

Telomere shortening velocity of patients administered with hypnotics is accelerated in a gender-differential manner

2020 ◽  
pp. 1-6
Author(s):  
Toyoki Maeda ◽  
Takahiko Horiuchi ◽  
Naoki Makino
Keyword(s):  
Telomere Length ◽  
The Other ◽  
Biological Aging ◽  
Shortening Velocity ◽  
Telomere Shortening ◽  
Female Patients ◽  
Associated Diseases ◽  
Other Hand ◽  
Male Patients ◽  
Gender Differential

The telomere length and its distribution were compared between patients administered with and without hypnotics to see if regular administration of hypnotics is associated with their aging-related somatic telomere shortening. Male patients presented significant shortening of telomere length of circulating leukocytes in association with age (–41.9 bp/year, p = 0.045) in contrast with controls (–18.3 kb/year, p = 0.155). On the other hand, female patients presented no significant shortening of telomere length with aging (–16.4 bp/year, p = 0.372) in contrast with controls (–55.9 bp/year, p = 0.00005). These results suggested that regular administration of hypnotics is associated with aging progression in a gender-related manner. The administration of hypnotics could be an indicator as the somatic aging status and for the screening of background lifestyle-associated diseases promoting biological aging.

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