scholarly journals Assessment of Telomere Length and Molecular Characterization of TERT Gene Promoter in Periampullary Carcinomas

2021 ◽  
Author(s):  
Cleandra Gregório ◽  
Shefali Thakur ◽  
Raquel Camara Rivero ◽  
Simone Márcia dos Santos Machado ◽  
Cyrille Cuenin ◽  
...  
Keyword(s):  
Protein Expression ◽  
Telomere Length ◽  
Gene Promoter ◽  
Ampulla Of Vater ◽  
Telomere Maintenance ◽  
Epigenetic Alterations ◽  
Dna Hypermethylation ◽  
Tert Gene ◽  
The Status ◽  
Periampullary Carcinomas

Abstract Genetic and epigenetic alterations of the telomere maintenance machinery like telomere length and telomerase reverse transcriptase (encoded by TERT gene) are reported in several human malignancies. However, there is limited knowledge on the status of the telomere machinery in periampullary carcinomas (PAC) that are rare and heterogeneous groups of cancers arising from different anatomic sites around the ampulla of Vater. In the current study, we investigated the relative telomere length (RTL) and the most frequent genetic and epigenetic alterations in the TERT promoter in PAC (n=20) and compared with tumor-adjacent nonpathological duodenum (NDu; n=16). We found shorter RTLs (1.27 vs 1.33, P=0.01) and lower TERT protein expression (p=0.04) in PAC tissues as compared to the NDu. Although we did not find any mutation at two reactivating hotspot mutation sites of the TERT promoter, we detected polymorphism in 55% (11/20) of the cases at rs2853669 (T>C). Also, we found a hypermethylated region in the TERT promoter of PACs consisting of four CpGs (cg10896616 with ∆β 7%; cg02545192 with ∆β 9%; cg03323598 with ∆β 19%; and cg07285213 with ∆β 15%). In conclusion, we identified shorter telomeres with DNA hypermethylation in the TERT promoter region and lower TERT protein expression in PAC tissues. Further studies with a larger sample size are necessary to substantiate these results.

scholarly journals Revisiting Telomere Shortening in Cancer

Cells ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 107 ◽  
Author(s):  
Keiji Okamoto ◽  
Hiroyuki Seimiya
Keyword(s):  
Cancer Cells ◽  
Telomere Length ◽  
Prognostic Biomarker ◽  
Telomere Maintenance ◽  
Epigenetic Alterations ◽  
Telomere Shortening ◽  
Normal Tissues ◽  
Genome Wide ◽  
Unlimited Growth ◽  
Protective Structures

Telomeres, the protective structures of chromosome ends are gradually shortened by each cell division, eventually leading to senescence or apoptosis. Cancer cells maintain the telomere length for unlimited growth by telomerase reactivation or a recombination-based mechanism. Recent genome-wide analyses have unveiled genetic and epigenetic alterations of the telomere maintenance machinery in cancer. While telomerase inhibition reveals that longer telomeres are more advantageous for cell survival, cancer cells often have paradoxically shorter telomeres compared with those found in the normal tissues. In this review, we summarize the latest knowledge about telomere length alterations in cancer and revisit its rationality. Finally, we discuss the potential utility of telomere length as a prognostic biomarker.

EPIGENETIC ALTERATIONS ASSOCIATED WITH PREMATURE OVARIAN FAILURE

2008 ◽  
Vol 31 (4) ◽  
pp. 11
Author(s):  
Manda Ghahremani ◽  
Courtney W Hannah ◽  
Maria Peneherrera ◽  
Karla L Bretherick ◽  
Margo R Fluker ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Premature Ovarian Failure ◽  
Promoter Region ◽  
Gene Promoter ◽  
Ovarian Failure ◽  
P Value ◽  
Epigenetic Alterations ◽  
Methylation Array ◽  
Cpg Sites ◽  
Deficient Mice

Background/Purpose: Premature ovarian failure (POF) affects 1% of women with a largely idiopathic and poorly understood etiology. The objective of this study was to identify specific epigenetic alterations by measuring DNA methylation of gene regulatory regions in women with POF vs. controls. Methods: Blood samples were collected from idiopathic POFpatients (Amenorrhea for at least 3 months and 2 serum FSH levels of > 40mIU/ml obtained > 1 month apart prior to age 40) and control women (CW) (healthy pregnancy after age 37 with out a pregnancy loss). Genomic DNA was extracted from EDTA anticoagulated blood and bisulfite converted for analysis using the Illumina Golden Gate Methylation Panel which measures DNA methylation at 1506 CpG sites in the promoter regions of 807 genes in 10 POF and 12 CW. Candidate genes with altered epigenetic marks between POF and CW at a nominal P-value < 0.05 were identified using a t-testcomparison within the Illumina bead studio software. Genes of interest were further analyzed for quantitative methylation at specific CpG sites using pyrosequencing in 30 POF and 30 CW. Results: Comparison of DNA methylation profiles of our initial POF and CW groups identified several genes with statistically significanthyper- or hypo- methylation in the POF group (P < 0.05), including the Androgen Receptor (AR)promoter region, which was significantly hypermethylated. To further validate these results, DNA methylation of the AR gene promoter was quantified bypryosequencing in a larger group of POF and CW. Pyrosequencing further confirmed a significantly higher DNA methylation of the AR promoter region inPOF vs. CW (P=0.007). Conclusions: This is a novel study identifying epigenetic alterations in POF. The hypermethylation of the AR gene in POF patients may cause decreased level of the AR in these women. This is especially interesting given a recent report of induced POF in AR deficient mice^1. Specific epigenetic markers, as identified by DNA methylation array profiling in blood, may serve as useful biomarkers for POF and other fertility disorders. However, it will need to be determined if these methylation changes are present prior to diagnosis, or are a consequence of menopause itself. Reference: 1.Hiroko S. et al. Premature ovarian failure in androgenreceptor deficient mice. PNAS;103:224-9

Non-canonical Functions of Telomerase Reverse Transcriptase: Emerging Roles and Biological Relevance

2020 ◽  
Vol 20 (6) ◽  
pp. 498-507 ◽  
Author(s):  
Connor A.H. Thompson ◽  
Judy M.Y. Wong
Keyword(s):  
Oxidative Stress ◽  
Dna Damage ◽  
Reverse Transcriptase ◽  
Cancer Cells ◽  
Telomere Length ◽  
Telomere Maintenance ◽  
Telomerase Reverse Transcriptase ◽  
Alternative Mechanism ◽  
Dependent Manner ◽  
Mitochondrial Integrity

Increasing evidence from research on telomerase suggests that in addition to its catalytic telomere repeat synthesis activity, telomerase may have other biologically important functions. The canonical roles of telomerase are at the telomere ends where they elongate telomeres and maintain genomic stability and cellular lifespan. The catalytic protein component Telomerase Reverse Transcriptase (TERT) is preferentially expressed at high levels in cancer cells despite the existence of an alternative mechanism for telomere maintenance (alternative lengthening of telomeres or ALT). TERT is also expressed at higher levels than necessary for maintaining functional telomere length, suggesting other possible adaptive functions. Emerging non-canonical roles of TERT include regulation of non-telomeric DNA damage responses, promotion of cell growth and proliferation, acceleration of cell cycle kinetics, and control of mitochondrial integrity following oxidative stress. Non-canonical activities of TERT primarily show cellular protective effects, and nuclear TERT has been shown to protect against cell death following double-stranded DNA damage, independent of its role in telomere length maintenance. TERT has been suggested to act as a chromatin modulator and participate in the transcriptional regulation of gene expression. TERT has also been reported to regulate transcript levels through an RNA-dependent RNA Polymerase (RdRP) activity and produce siRNAs in a Dicer-dependent manner. At the mitochondria, TERT is suggested to protect against oxidative stress-induced mtDNA damage and promote mitochondrial integrity. These extra-telomeric functions of TERT may be advantageous in the context of increased proliferation and metabolic stress often found in rapidly-dividing cancer cells. Understanding the spectrum of non-canonical functions of telomerase may have important implications for the rational design of anti-cancer chemotherapeutic drugs.

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 RAD50 and RAD51 Define Two Pathways That Collaborate to Maintain Telomeres in the Absence of Telomerase

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 143-152 ◽  
Author(s):  
Siyuan Le ◽  
J Kent Moore ◽  
James E Haber ◽  
Carol W Greider
Keyword(s):  
Cell Death ◽  
Telomere Length ◽  
Gene Conversion ◽  
De Novo ◽  
Dna Recombination ◽  
Telomere Maintenance ◽  
Triple Mutant ◽  
Yeast Telomerase ◽  
Telomere Lengthening

Abstract Telomere length is maintained by the de novo addition of telomere repeats by telomerase, yet recombination can elongate telomeres in the absence of telomerase. When the yeast telomerase RNA component, TLC1, is deleted, telomeres shorten and most cells die. However, gene conversion mediated by the RAD52 pathway allows telomere lengthening in rare survivor cells. To further investigate the role of recombination in telomere maintenance, we assayed telomere length and the ability to generate survivors in several isogenic DNA recombination mutants, including rad50, rad51, rad52, rad54, rad57, xrs2, and mre11. The rad51, rad52, rad54, and rad57 mutations increased the rate of cell death in the absence of TLC1. In contrast, although the rad50, xrs2, and mre11 strains initially had short telomeres, double mutants with tlc1 did not affect the rate of cell death, and survivors were generated at later times than tlc1 alone. While none of the double mutants of recombination genes and tlc1 (except rad52 tlc1) blocked the ability to generate survivors, a rad50 rad51 tlc1 triple mutant did not allow the generation of survivors. Thus RAD50 and RAD51 define two separate pathways that collaborate to allow cells to survive in the absence of telomerase.

scholarly journals WGS-based telomere length analysis in Dutch family trios implicates stronger maternal inheritance and a role for RRM1 gene

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Lilit Nersisyan ◽  
◽  
Maria Nikoghosyan ◽  
Arsen Arakelyan
Keyword(s):  
Telomere Length ◽  
Telomere Maintenance ◽  
Whole Genome Sequencing Data ◽  
Sequencing Data ◽  
Association Analyses ◽  
Relative Contribution ◽  
Age Related ◽  
Small Influence ◽  
Ribonuclease Reductase ◽  
Length Analysis

AbstractTelomere length (TL) regulation is an important factor in ageing, reproduction and cancer development. Genetic, hereditary and environmental factors regulating TL are currently widely investigated, however, their relative contribution to TL variability is still understudied. We have used whole genome sequencing data of 250 family trios from the Genome of the Netherlands project to perform computational measurement of TL and a series of regression and genome-wide association analyses to reveal TL inheritance patterns and associated genetic factors. Our results confirm that TL is a largely heritable trait, primarily with mother’s, and, to a lesser extent, with father’s TL having the strongest influence on the offspring. In this cohort, mother’s, but not father’s age at conception was positively linked to offspring TL. Age-related TL attrition of 40 bp/year had relatively small influence on TL variability. Finally, we have identified TL-associated variations in ribonuclease reductase catalytic subunit M1 (RRM1 gene), which is known to regulate telomere maintenance in yeast. We also highlight the importance of multivariate approach and the limitations of existing tools for the analysis of TL as a polygenic heritable quantitative trait.

scholarly journals DNA Hypermethylation of a panel of genes as an urinary biomarker for bladder cancer diagnosis

2021 ◽  
Author(s):  
Petros Georgopoulos ◽  
Maria Papaioannou ◽  
Soultana Markopoulou ◽  
Aikaterini Fragou ◽  
George Kouvatseas ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Bladder Cancer ◽  
Smoking Status ◽  
Gene Promoter ◽  
Control Group ◽  
Gene Promoters ◽  
Dna Hypermethylation ◽  
Diagnostic Potential ◽  
Specificity And Sensitivity ◽  
Promoter Dna

Abstract PurposeThe aim of this study was to explore the diagnostic potential of a panel of five hypermethylated gene promoters in bladder cancer. Individuals with primary BCa and control individuals matching the gender, age and smoking status of the cancer patients were recruited. DNA methylation was assessed for the gene promoters of RASSF1, RARβ, DAPK, hTERT and APC in urine samples collected by spontaneous urination. Fifty patients and 35 healthy controls were recruited, with average age of 70.26 years and average smoking status of 44.78 pack-years. In the BCa group, DNA methylation was detected in 27(61.4%) samples. RASSF1 was methylated in 52.2% of samples. Only 3(13.6%) samples from the control group were methylated, all in the RASSF1 gene promoter. The specificity and sensitivity of this panel of genes to diagnose BCa was 86% and 61% respectively. The RASSF1 gene could diagnose BCa with specificity 86.4% and sensitivity 52.3%. Promoter DNA methylation of this panel of five genes could be further investigated as urine biomarker for the diagnosis of BCa. The RASSF1 could be a single candidate biomarker for predicting BCa patients versus controls. Studies are required in order to develop a geographically adjusted diagnostic biomarker for BCa.Trial registration: ACTRN12620000258954

scholarly journals Loss of protein expression and recurrent DNA hypermethylation of the GNG7 gene in squamous cell carcinoma of the head and neck

2011 ◽  
Vol 53 (2) ◽  
pp. 167-174 ◽  
Author(s):  
Sylvia Hartmann ◽  
Marcin Szaumkessel ◽  
Itziar Salaverria ◽  
Ronald Simon ◽  
Guido Sauter ◽  
...  
Keyword(s):  
Squamous Cell Carcinoma ◽  
Protein Expression ◽  
Cell Carcinoma ◽  
Head And Neck ◽  
Squamous Cell ◽  
Dna Hypermethylation
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