ABSTRACT
MiRNAs, a class of non-coding RNA molecules, have emerged as critical modulators of telomere length and telomerase activity by finely tuning the expression of target genes (and not gene targets) within signaling pathways involved in telomere homeostasis. The primary objective of this systematic review was to compile and synthesize the existing body of knowledge on the role, association, and involvement of miRNAs in telomere length. Additionally, the review explored the regulation, function, and activation mechanism of the human telomerase reverse transcriptase (hTERT) gene and telomerase activity in tumor cells. A comprehensive analysis of 47 selected articles revealed 40 distinct miRNAs involved in these processes. These miRNAs were shown to exert their function, in both clinical cases and cell line models, either directly or indirectly, regulating hTERT and telomerase activity through distinct molecular mechanisms. The regulatory roles of these miRNAs significantly affected major cancer phenotypes, with outcomes largely dependent on the tissue type and the cellular actions within the tumor cells, whereby they functioned as oncogenes or tumor suppressors. These findings strongly support the pivotal role of miRNAs in modulating telomere length and telomerase activity, thereby contributing to the intricate and complex regulation of telomere homeostasis in tumor cells. Moreover, they emphasize the potential of targeting miRNAs and key regulatory genes as therapeutic strategies to disrupt cancer cell growth and promote senescence, offering promising avenues for novel cancer treatments.
Subject(s)
Gene Expression Regulation, Neoplastic , MicroRNAs , Neoplasms , Telomerase , Telomere Homeostasis , Telomere , Humans , Telomerase/genetics , Telomerase/metabolism , MicroRNAs/genetics , MicroRNAs/metabolism , Telomere Homeostasis/genetics , Neoplasms/genetics , Neoplasms/pathology , Neoplasms/metabolism , Telomere/metabolism , Telomere/genetics , AnimalsABSTRACT
BACKGROUND: Telomeropathies are a group of inherited disorders caused by germline pathogenic variants in genes involved in telomere maintenance, resulting in excessive telomere attrition that affects several tissues, including hematopoiesis. RecQ and RTEL1 helicases contribute to telomere maintenance by unwinding telomeric structures such as G-quadruplexes (G4), preventing replication defects. Germline RTEL1 variants also are etiologic in telomeropathies. METHODS AND RESULTS: Here we investigated the expression of RecQ (RECQL1, BLM, WRN, RECQL4, and RECQL5) and RTEL1 helicase genes in peripheral blood mononuclear cells (PBMCs) from human telomeropathy patients. The mRNA expression levels of all RecQ helicases, but not RTEL1, were significantly downregulated in patients' primary cells. Reduced RecQ expression was not attributable to cell proliferative exhaustion, as RecQ helicases were not attenuated in T cells exhausted in vitro. An additional fifteen genes involved in DNA damage repair and RecQ functional partners also were downregulated in the telomeropathy cells. CONCLUSION: These findings indicate that the expression of RecQ helicases and functional partners involved in DNA repair is downregulated in PBMCs of telomeropathy patients.
Subject(s)
Leukocytes, Mononuclear , RecQ Helicases , Adult , Female , Humans , Male , DNA Helicases/genetics , DNA Helicases/metabolism , DNA Repair/genetics , Leukocytes, Mononuclear/metabolism , RecQ Helicases/genetics , RecQ Helicases/metabolism , Telomere/metabolism , Telomere/genetics , Telomere Homeostasis/geneticsABSTRACT
OBJECTIVES: Lifestyle, obesity, and eating habits are emerging as determinants for the instability of telomeres. The increase in childhood and adolescent obesity and the association of biochemical profiles and dietary components with telomere length (TL) makes it an important issue in nutritional research. The aim of the present study was to investigate TL and its association with ethnic background, adiposity, clinical and biochemical parameters, and dietary patterns among Brazilian children and adolescents. METHODS: A cross-sectional study encompassing 981 children and adolescents between 7 and 17 y of age was performed. Dietary intake habits, anthropometry, and clinical data were collected. TL analysis was performed by quantitative polymerase chain reaction. RESULTS: Children presented significantly longer TL than adolescents (P = 0.046). Participants who self-declared as black, mulatto, or brown (P < 0.001) also showed longer TL than those who were white. Regarding biochemical parameters, individuals with altered glucose levels had shorter TL than normoglycemic participants in the total sample (P = 0.014). Such difference remained statistically significant in adolescents (P = 0.019). Participants who reported eating fruits and vegetables regularly had longer TL than those who did not (P < 0.001). CONCLUSION: The results suggested that both biochemical parameters and the intake of antioxidant-rich food, such as fruits and vegetables, are associated with the stability of telomere biology among young Brazilians.
Subject(s)
Ethnicity/genetics , Feeding Behavior/physiology , Pediatric Obesity/ethnology , Pediatric Obesity/genetics , Telomere Homeostasis/genetics , Adiposity/genetics , Adolescent , Anthropometry , Brazil , Child , Cross-Sectional Studies , Diet/adverse effects , Feeding Behavior/ethnology , Female , Humans , Male , TelomereABSTRACT
Telomeropathies involve a wide variety of infrequent genetic diseases caused by mutations in the telomerase maintenance mechanism or the DNA damage response (DDR) system. They are considered a family of rare diseases that often share causes, molecular mechanisms and symptoms. Generally, these diseases are not diagnosed until the symptoms are advanced, diminishing the survival time of patients. Although several related syndromes may still be unrecognized this work describes those that are known, highlighting that because they are rare diseases, physicians should be trained in their early diagnosis. The etiology and diagnosis are discussed for each telomeropathy and the treatments when available, along with a new classification of this group of diseases. Ethical and legal issues related to this group of diseases are also considered.
Subject(s)
DNA Damage , Genetic Diseases, Inborn/diagnosis , Genetic Diseases, Inborn/therapy , Telomerase/genetics , Telomere Homeostasis , Anticipation, Genetic , Ethics, Medical , Genetic Association Studies , Genetic Markers , Genetic Testing , Genetic Variation , Humans , Mutation , Phenotype , Rare Diseases , Telomerase/metabolism , Telomere/genetics , Telomere/metabolism , Telomere Homeostasis/geneticsABSTRACT
OBJECTIVE: We evaluated the association between cognitive deficits and leukocyte telomere length (LTL) in HIV-1-infected individuals. DESIGN: 73 HIV-1-infected patients undergoing neuropsychological evaluation and 91 healthy controls were included in this study. Fifteen HIV-1 positive patients did not have cognitive disorders whereas 26 had asymptomatic neurocognitive disorder (ANI), 13 presented mild to moderate neurocognitive disorder (MND), and 10 had HIV-associated dementia (HAD). METHODS: DNA from the peripheral blood of HIV-1-infected patients was used for measurement of telomere length by real-time PCR. HIV-1 viral load was determined in blood. RESULTS: LTL decreased with age in healthy controls (p=0.0001). Regardless of the HIV status, age-matched LTL from HIV patients, including those with ANI and MND, were shortened in comparison to the healthy control group (p=0.0073); however, no association was found among the HIV-1-infected individuals with cognitive deficits (p=0.01). In addition, no gender-related association with LTL was observed (p=0.80), smoking, physical exercise, and plasma viral load were not correlated to telomere length (p=0.66). CONCLUSIONS: We concluded that leukocyte telomere length may not be a marker of cellular senescence in individuals with HIV infection and neurocognitive disorders.
Subject(s)
HIV Infections/genetics , HIV Infections/psychology , HIV-1 , Neurocognitive Disorders/genetics , Neurocognitive Disorders/virology , Telomere Homeostasis/genetics , Telomere/genetics , Age Factors , Analysis of Variance , Case-Control Studies , Female , Humans , Leukocytes/virology , Male , Middle Aged , Neuropsychological Tests , Real-Time Polymerase Chain Reaction , Reference Values , Statistics, Nonparametric , Surveys and Questionnaires , Viral LoadABSTRACT
Limitless replicative potential is one of the hallmarks of cancer that is mainly due to the activity of telomerase. This holoenzyme maintains telomere length, adding TTAGGG repetitions at the end of chromosomes in each cell division. In addition to this function, there are extratelomeric roles of telomerase that are involved in cancer promoting events. It has been demonstrated that TERT, the catalytic component of telomerase, acts as a transcriptional modulator in many signaling pathways. Taking into account this evidence and our experience on the study of azidothymidine (AZT) as an inhibitor of telomerase activity, the present study analyzes the effect of AZT on some telomeric and extratelomeric activities. To carry out the present study, we evaluated the transcription of genes that are modulated by the Wnt/ß-catenin pathway, such as c-Myc and cyclin-D1 (Cyc-D1) and cell processes related with their expression, such as, proliferation, modifications of the actin cytoskeleton, cell migration and cell cycle in a mammary carcinoma cell line (F3II). Results obtained after treatment with AZT (600 µM) for 15 passages confirmed the inhibitory effect on telomerase. Regarding extratelomeric activities, our results showed a decrease of 64, 38 and 25% in the transcription of c-Myc, Cyc-D1 and TERT, respectively (p<0.05) after AZT treatment. Furthermore, we found an effect on cell migration, reaching an inhibition of 48% (p<0.05) and a significant passage-dependent increase on cell doubling time during treatment. Finally, we evaluated the effect on cell cycle, obtaining a decline in G0/G1 in AZT-treated cells. These results allow us to postulate that AZT is not only an inhibitor of telomerase activity, but also a potential modulator of extratelomeric processes involved in cancer promotion.
Subject(s)
Adenocarcinoma/drug therapy , Breast Neoplasms/drug therapy , Cyclin D1/biosynthesis , Proto-Oncogene Proteins c-myc/biosynthesis , Telomerase/genetics , Zidovudine/administration & dosage , Actin Cytoskeleton/drug effects , Adenocarcinoma/genetics , Adenocarcinoma/pathology , Animals , Apoptosis/drug effects , Breast Neoplasms/genetics , Breast Neoplasms/pathology , Cell Division/genetics , Cell Movement/drug effects , Cell Proliferation/drug effects , Cyclin D1/genetics , Disease Models, Animal , Female , Humans , Proto-Oncogene Proteins c-myc/genetics , Telomerase/antagonists & inhibitors , Telomerase/biosynthesis , Telomere Homeostasis/genetics , Wnt Signaling Pathway/drug effects , beta Catenin/geneticsABSTRACT
We tested the hypothesis that leukocyte telomere length (LTL) is associated with birth weight in both extremes of abnormal fetal growth: small (SGA) and large for gestational age newborns (LGA). Clinical and laboratory variables of the mothers and the neonates were explored; 45 newborns with appropriate weight for gestational age (AGA), 12 SGA and 12 LGA were included. Whether the differences might be explained by variation in OBFC1 (rs9419958) and CTC1 (rs3027234) genes associated with LTL was determined. A significant association between birth weight and LTL was observed; LTL was significantly shorter in LGA newborns (1.01 ± 0.12) compared with SGA (1.73 ± 0.19) p < 0.005, mean ± SE. Maternal (Spearman R = -0.6, p = 0.03) and neonatal LTL (R = -0.25, p = 0.03) were significantly and inversely correlated with maternal history of arterial hypertension in previous gestations. Neonatal LTL was not significantly associated with either rs9419950 or rs3027234, suggesting that the association between neonatal LTL and birth weight is not influenced by genetic variation in genes that modify the interindividual LTL. In conclusion, telomere biology seems to be modulated by abnormal fetal growth; modifications in telomere length might be programmed by an adverse environment in utero.
Subject(s)
Fetal Development/genetics , Hypertension/genetics , Telomere Homeostasis/genetics , Telomere-Binding Proteins/genetics , Adult , Birth Weight/genetics , Birth Weight/radiation effects , Female , Fetal Development/physiology , Genetic Association Studies , Humans , Hypertension/physiopathology , Infant, Newborn , Leukocytes/pathology , Pregnancy , Telomere/geneticsABSTRACT
Studies in humans suggest that leukocyte telomere length may act as a marker of biological aging. We investigated whether individuals in the Nicoya region of Costa Rica, known for exceptional longevity, had longer telomere length than those in other parts of the country. After controlling for age, age squared, rurality, rainy season and gender, the mean leukocyte telomere length in Nicoya was substantially longer (81 base pairs, p<0.05) than in other areas of Costa Rica, providing evidence of a biological pathway to which this notable longevity may be related. This relationship remains unchanged (79 base pairs, p<0.05) after statistically controlling for nineteen potential biological, dietary and social and demographic mediators. Thus the difference in the mean leukocyte telomere length that characterizes this unique region does not appear to be explainable by traditional behavioral and biological risk factors. More detailed examination of mean leukocyte telomere length by age shows that the regional telomere length difference declines at older ages.
Subject(s)
Aging/genetics , Longevity/genetics , Telomere Homeostasis/genetics , Telomere/genetics , Aged , Aged, 80 and over , Costa Rica , Female , Genetics, Population , Humans , Leukocytes/metabolism , MaleABSTRACT
Smoking and diabetes, consistent risk factors for pancreatic cancer, are also factors that influence telomere length maintenance. To test whether telomere length is associated with pancreatic cancer risk, we conducted a nested case-control study in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study cohort of male smokers, aged 50-69 years at baseline. Between 1992 and 2004, 193 incident cases of pancreatic adenocarcinoma occurred (mean follow-up from blood draw: 6.3 years) among participants with whole blood samples available for telomere length assays. For these cases and 660 controls, we calculated odds ratios (OR) and 95% confidence intervals using unconditional logistic regression, adjusting for age, number of years smoked regularly, and history of diabetes mellitus. Telomere length was categorized into quartiles (shortest to longest) and analyzed as both a categorical and a continuous normal variable (reported per 0.2 unit increase in telomere length). All statistical tests were two-sided. Longer telomere length was significantly associated with increased pancreatic cancer risk (continuous OR = 1.26 95% CI = 1.09-1.46; highest quartile compared to lowest, OR = 1.57, 95% CI = 1.01-2.43, p-trend = 0.007). This association remained for subjects diagnosed within the first five years of blood draw (continuous OR = 1.46, 95% CI = 1.19-1.79 highest quartile OR = 2.92, 95% CI = 1.47-5.77, p-trend = 0.002), but not those diagnosed greater than five years after blood draw (continuous OR = 1.03, 95% CI = 0.85-1.22; highest quartile OR = 1.04, 95% CI = 0.60-1.79). This is the first prospective study to suggest an association between longer blood leukocyte telomere length and increased pancreatic cancer risk.
Subject(s)
Pancreatic Neoplasms/pathology , Telomere Homeostasis/genetics , alpha-Tocopherol/administration & dosage , beta Carotene/administration & dosage , Aged , Case-Control Studies , Humans , Logistic Models , Male , Middle Aged , Pancreatic Neoplasms/epidemiology , Pancreatic Neoplasms/etiology , Pancreatic Neoplasms/genetics , Prospective Studies , Risk Factors , Smoking/adverse effects , Telomere Homeostasis/drug effectsABSTRACT
Dyskeratosis congenita (DC) encompasses a large spectrum of diseases and clinical manifestations generally related to premature aging, including bone marrow failure and cancer predisposition. The major risk factor for DC is to carry germline telomere-related mutations - in telomerase or telomere shelterin genes - which results in premature telomere dysfunction, thus increasing the risk of premature aging impairments. Despite the advances that have been accomplished in DC research, the molecular aspects underlying the phenotypic variability of the disease remain poorly understood. Here different aspects of telomere biology, concerning adult stem cells senescence, tumor suppression and cancer are considered in the context of DC, resulting in two translational models: late onset of DC symptoms in telomere-related mutations carriers is a potential indicator of increased cancer risk and differences in tumor suppression capacities among the genetic subgroups are (at least partial) causes of different clinical manifestations of the disease. The limitations of both models are presented, and further experiments for their validation, as well as clinical implications, are discussed.