Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 13.071
Filtrar
1.
Int J Mol Sci ; 22(7)2021 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-33810359

RESUMO

Despite the strong evidence for the immunomodulatory activity of mesenchymal stromal cells (MSCs), clinical trials have so far failed to clearly show benefit, likely reflecting methodological shortcomings and lack of standardization. MSC-mediated tissue repair is commonly believed to occur in a paracrine manner, and it has been stated that extracellular vesicles (EVs) secreted by MSCs (EVMSC) are able to recapitulate the immunosuppressive properties of parental cells. As a next step, clinical trials to corroborate preclinical studies should be performed. However, effective dose in large mammals, including humans, is quite high and EVs industrial production is hindered by the proliferative senescence that affects MSCs during massive cell expansion. We generated a genetically modified MSC cell line overexpressing hypoxia-inducible factor 1-alpha and telomerase to increase the therapeutic potency of EVMSC and facilitate their large-scale production. We also developed a cytokine-based preconditioning culture medium to prime the immunomodulatory response of secreted EVs (EVMSC-T-HIFc). We tested the efficacy of this system in vitro and in a delayed-type hypersensitivity mouse model. MSC-T with an HIF-1α-GFP lentiviral vector (MSC-T-HIF) can be effectively expanded to obtain large amounts of EVs without major changes in cell phenotype and EVs composition. EVMSC-T-HIFc suppressed the proliferation of activated T-cells more effectively than did EVs from unmodified MSC in vitro, and significantly blunted the ear-swelling response in vivo by inhibiting cell infiltration and improving tissue integrity. We have developed a long-lived EV source that secretes high quantities of immunosuppressive EVs, facilitating a more standard and cost-effective therapeutic product.


Assuntos
Vesículas Extracelulares/transplante , Hipersensibilidade Tardia/terapia , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Imunomodulação , Transplante de Células-Tronco Mesenquimais/métodos , Células-Tronco Mesenquimais/metabolismo , Linfócitos T/imunologia , Animais , Linhagem Celular , Proliferação de Células , Células Cultivadas , Citocinas/farmacologia , Polpa Dentária/citologia , Vesículas Extracelulares/imunologia , Vetores Genéticos/genética , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Lentivirus/genética , Masculino , Células-Tronco Mesenquimais/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Engenharia de Proteínas/métodos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Linfócitos T/fisiologia , Telomerase/genética , Telomerase/metabolismo , Adulto Jovem
2.
Adv Exp Med Biol ; 1286: 135-143, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33725351

RESUMO

Telomerases are attractive targets for development of new anticancer agents. Most tumors express the enzyme telomerase that maintains telomere length and thus ensures indefinite cell proliferation, a hallmark of cancer. Curcumin has been shown to be effective against several types of malignancies and has also been shown to have inhibitory effects on telomerase activity. Hence, the aim of this chapter is to review the available investigations of curcumin on telomerase activity. Based on the findings obtained from the different studies here, we conclude that the telomerase inhibitory effects of curcumin are integral to its anticancer activity, and thus curcumin may be useful therapeutically in the cancer field.


Assuntos
Antineoplásicos , Curcumina , Neoplasias , Telomerase , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Proliferação de Células , Curcumina/farmacologia , Curcumina/uso terapêutico , Humanos , Neoplasias/tratamento farmacológico , Telomerase/genética , Telômero/metabolismo
3.
Int J Mol Sci ; 22(4)2021 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33670111

RESUMO

The gene coding for the telomerase reverse transcriptase (TERT) is essential for the maintenance of telomeres. Previously we described the presence of three TERT paralogs in the allotetraploid plant Nicotiana tabacum, while a single TERT copy was identified in the paleopolyploid model plant Arabidopsis thaliana. Here we examine the presence, origin and functional status of TERT variants in allotetraploid Nicotiana species of diverse evolutionary ages and their parental genome donors, as well as in other diploid and polyploid plant species. A combination of experimental and in silico bottom-up analyses of TERT gene copies in Nicotiana polyploids revealed various patterns of retention or loss of parental TERT variants and divergence in their functions. RT-qPCR results confirmed the expression of all the identified TERT variants. In representative plant and green algal genomes, our synteny analyses show that their TERT genes were located in a conserved locus that became advantageous after the divergence of eudicots, and the gene was later translocated in several plant groups. In various diploid and polyploid species, translocation of TERT became fixed in target loci that show ancient synapomorphy.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Dosagem de Genes , Poliploidia , Telomerase , Tabaco , Arabidopsis/enzimologia , Arabidopsis/genética , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Telomerase/genética , Telomerase/metabolismo , Tabaco/enzimologia , Tabaco/genética
4.
Int J Mol Sci ; 22(4)2021 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-33672524

RESUMO

Human bone marrow stem cells (HBMSCs) are isolated from the bone marrow. Stem cells can self-renew and differentiate into various types of cells. They are able to regenerate kinds of tissue that are potentially used for tissue engineering. To maintain and expand these cells under culture conditions is difficult-they are easily triggered for differentiation or death. In this study, we describe a new culture formula to culture isolated HBMSCs. This new formula was modified from NCDB 153, a medium with low calcium, supplied with 5% FBS, extra growth factor added to it, and supplemented with N-acetyl-L-cysteine and L-ascorbic acid-2-phosphate to maintain the cells in a steady stage. The cells retain these characteristics as primarily isolated HBMSCs. Moreover, our new formula keeps HBMSCs with high proliferation rate and multiple linage differentiation ability, such as osteoblastogenesis, chondrogenesis, and adipogenesis. It also retains HBMSCs with stable chromosome, DNA, telomere length, and telomerase activity, even after long-term culture. Senescence can be minimized under this new formulation and carcinogenesis of stem cells can also be prevented. These modifications greatly enhance the survival rate, growth rate, and basal characteristics of isolated HBMSCs, which will be very helpful in stem cell research.


Assuntos
Antioxidantes/farmacologia , Cálcio/farmacologia , Senescência Celular , Meios de Cultura/química , Células-Tronco Mesenquimais/citologia , Antígenos CD/metabolismo , Biomarcadores/metabolismo , Diferenciação Celular/efeitos dos fármacos , Linhagem da Célula/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Separação Celular , Forma Celular/efeitos dos fármacos , Células Cultivadas , Senescência Celular/efeitos dos fármacos , Dano ao DNA , Humanos , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteoblastos/metabolismo , Telomerase/metabolismo , Homeostase do Telômero , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/metabolismo
5.
Methods Mol Biol ; 2292: 133-141, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33651358

RESUMO

Bladder cancer with an incidence of 15 cases per 100,000 persons in the global population is the most common tumor of the urinary tract. Imaging techniques, cytoscopy, and cytology are not sufficiently accurate to detect early stage tumors, and the need for new diagnostic markers is still an urgency. Among the biomarkers most recently proposed to improve diagnostic accuracy and especially sensitivity, increasing attention has been focused on the role of the ribonucleoprotein, telomerase. Previous studies have shown that the quantitative telomerase repeat amplification protocol (TRAP) assay performed in voided urine is an important noninvasive tool for the diagnosis of bladder tumors since it has very high sensitivity and specificity, even for early stage and low-grade tumors. Telomerase activity in urine determined by TRAP seems to be marker of great potential, even more advantageous in cost-benefit terms when used in selected symptomatic patients or professionally high-risk subgroups. Here we report the real-time PCR protocol to detect telomerase activity in urine sediment for bladder cancer.


Assuntos
Telomerase/urina , Neoplasias da Bexiga Urinária/urina , Biomarcadores Tumorais/urina , Ensaios Enzimáticos/métodos , Humanos , Reação em Cadeia da Polimerase em Tempo Real/métodos , Coleta de Urina/métodos
6.
Crit Rev Oncol Hematol ; 160: 103288, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33675908

RESUMO

We conducted a systematic review and meta-analysis of the association between somatic mutations of the TERT gene promoter and melanoma survival. Data from nineteen independent studies (>2,500 melanoma overall) were pooled using random effects meta-analysis models. TERT-mutated melanoma patients had a significantly worse overall survival (OS) (summary hazard ratio 1.43, 95 % confidence intervals (CI) 1.05-1.95) compared to wild-type ones. The association became stronger when combining risk estimates for overall and melanoma-specific survival (MSS) (1.52, 95 % CI 1.14-2.02), and when restricting the analysis to studies mostly based on invasive non-acral cutaneous melanomas (1.77, 95 % CI 1.00-3.15). Limited, yet suggestive evidence of a detrimental effect of TERT promoter mutations on melanoma prognosis emerged also for other survival measures (e.g. disease-free and distant metastasis-free survival). We found suggestive evidence of a detrimental effect of TERT mutations on melanoma patients' survival.


Assuntos
Melanoma , Neoplasias Cutâneas , Telomerase , Humanos , Melanoma/genética , Mutação , Prognóstico , Neoplasias Cutâneas/genética , Telomerase/genética
8.
Biol Lett ; 17(3): 20200745, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33726560

RESUMO

The role of telomerase reverse transcriptase has been widely investigated in the contexts of ageing and age-related diseases. Interestingly, decreased telomerase activities (and accelerated telomere shortening) have also been reported in patients with emotion-related disorders, opening the possibility for subjective appraisal of stressful stimuli playing a key role in stress-driven telomere shortening. In fact, patients showing a pessimistic judgement bias have shorter telomeres. However, in humans the evidence for this is correlational and the causal directionality between pessimism and telomere shortening has not been established experimentally yet. We have developed and validated a judgement bias experimental paradigm to measure subjective evaluations of ambiguous stimuli in zebrafish. This behavioural assay allows classification of individuals in an optimistic-pessimistic dimension (i.e. from individuals that consistently evaluate ambiguous stimuli as negative to others that perceive them as positive). Using this behavioural paradigm we found that telomerase-deficient zebrafish (tert-/-) were more pessimistic in response to ambiguous stimuli than wild-type zebrafish. The fact that individuals with constitutive shorter telomeres have pessimistic behaviours demonstrates for the first time in a vertebrate model a genetic basis of judgement bias.


Assuntos
Pessimismo , Telomerase , Animais , Telomerase/genética , Telomerase/metabolismo , Telômero/genética , Encurtamento do Telômero , Peixe-Zebra/genética
9.
Medicine (Baltimore) ; 100(13): e25346, 2021 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-33787635

RESUMO

RATIONALE: Glioblastoma is the most lethal and common malignant brain tumor but rare in patients with neurofibromatosis type 1. The clinical findings and pathological findings with gene signatures in female patients have not been well clarified. PATIENT CONCERNS: A 51-year-old female patient complained of headache and left limb weakness lasting for 20 days. The patient underwent a cesarean section 20 years ago and hysterectomy 1 year ago because of uterine leiomyomas. Multiple café-au-lait spots and neurofibromas were found over patient's chest, neck, back, and arms. The myodynamia of left distant and proximate epipodite were grade 0 and grade 1 respectively. The myodynamia of lower left limb was grade 3. DIAGNOSES: Magnetic resonance imaging revealed a malignant lesion which was most likely a glioblastoma in the right temporo-parietal lobe, approximately 5.6 × 5.9 × 6.9 cm in size with a rounded boundary. INTERVENTIONS: A right temporo-parietal craniotomy was performed to resect the space-occupying lesion for gross total removal. Then, the patient received concurrent chemoradiotherapy. Histological examination confirmed a glioblastoma without v-RAF murine sarcoma viral oncogene homolog B1 gene, isocitrate dehydrogenase 1 gene, and telomerase reverse transcriptase gene promoter mutations. OUTCOMES: After surgery, the headache was relieved and the muscular strength of left limbs did improve. After receiving the standard treatment regimen, the patient was alive at 13 months follow-up. LESSONS: This is the first reported glioblastoma in female neurofibromatosis type 1 patient without v-RAF murine sarcoma viral oncogene homolog B1 gene, isocitrate dehydrogenase 1 gene, and telomerase reverse transcriptase gene promoter mutations. Tumors in adult patients with these signatures were less aggressive with well-circumscribed border and had long-term survivals which strengthened the evidence that these patients may comprise a unique subset in glioblastoma.


Assuntos
Biomarcadores Tumorais/genética , Neoplasias Encefálicas/diagnóstico , Glioblastoma/diagnóstico , Neurofibromatose 1/diagnóstico , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/patologia , Neoplasias Encefálicas/cirurgia , Craniotomia , Feminino , Glioblastoma/genética , Glioblastoma/patologia , Glioblastoma/cirurgia , Humanos , Isocitrato Desidrogenase/genética , Imagem por Ressonância Magnética , Pessoa de Meia-Idade , Mutação , Neurofibromatose 1/complicações , Neurofibromatose 1/genética , Lobo Parietal/diagnóstico por imagem , Lobo Parietal/patologia , Lobo Parietal/cirurgia , Regiões Promotoras Genéticas/genética , Proteínas Proto-Oncogênicas B-raf/genética , Telomerase/genética , Lobo Temporal/diagnóstico por imagem , Lobo Temporal/patologia , Lobo Temporal/cirurgia , Transcriptoma/genética
10.
BMC Cancer ; 21(1): 310, 2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33761896

RESUMO

BACKGROUND: Chromosomal inversions involving anaplastic lymphoma kinase (ALK) and echinoderm microtubule associated protein like 4 (EML4) generate a fusion protein EML4-ALK in non-small cell lung cancer (NSCLC). The understanding of EML4-ALK function can be improved by a functional study using normal human cells. METHODS: Here we for the first time conduct such study to examine the effects of EML4-ALK on cell proliferation, cellular senescence, DNA damage, gene expression profiles and transformed phenotypes. RESULTS: The lentiviral expression of EML4-ALK in mortal, normal human fibroblasts caused, through its constitutive ALK kinase activity, an early induction of cellular senescence with accumulated DNA damage, upregulation of p16INK4A and p21WAF1, and senescence-associated ß-galactosidase (SA-ß-gal) activity. In contrast, when EML4-ALK was expressed in normal human fibroblasts transduced with telomerase reverse transcriptase (hTERT), which is activated in the vast majority of NSCLC, the cells showed accelerated proliferation and acquired anchorage-independent growth ability in soft-agar medium, without accumulated DNA damage, chromosome aberration, nor p53 mutation. EML4-ALK induced the phosphorylation of STAT3 in both mortal and hTERT-transduced cells, but RNA sequencing analysis suggested that the different signaling pathways contributed to the different phenotypic outcomes in these cells. While EML4-ALK also induced anchorage-independent growth in hTERT-immortalized human bronchial epithelial cells in vitro, the expression of EML4-ALK alone did not cause detectable in vivo tumorigenicity in immunodeficient mice. CONCLUSIONS: Our data indicate that the expression of hTERT is critical for EML4-ALK to manifest its in vitro transforming activity in human cells. This study provides the isogenic pairs of human cells with and without EML4-ALK expression.


Assuntos
Carcinogênese/genética , Carcinoma Pulmonar de Células não Pequenas/genética , Neoplasias Pulmonares/genética , Proteínas de Fusão Oncogênica/metabolismo , Telomerase/metabolismo , Animais , Carcinogênese/patologia , Carcinoma Pulmonar de Células não Pequenas/patologia , Linhagem Celular , Proliferação de Células/genética , Senescência Celular/genética , Dano ao DNA , Modelos Animais de Doenças , Células Epiteliais , Feminino , Fibroblastos , Regulação Neoplásica da Expressão Gênica , Vetores Genéticos/genética , Humanos , Lentivirus/genética , Neoplasias Pulmonares/patologia , Camundongos , Proteínas de Fusão Oncogênica/genética , RNA-Seq , Telomerase/genética , Homeostase do Telômero/genética , Transfecção
11.
Nucleic Acids Res ; 49(5): 2848-2858, 2021 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-33589924

RESUMO

The ubiquitous RNA-binding protein HuR (ELAVL1) promotes telomerase activity by associating with the telomerase noncoding RNA TERC. However, the role of the neural-specific members HuB, HuC, and HuD (ELAVL2-4) in telomerase activity is unknown. Here, we report that HuB and HuD, but not HuC, repress telomerase activity in human neuroblastoma cells. By associating with AU-rich sequences in TERC, HuB and HuD repressed the assembly of the TERT-TERC core complex. Furthermore, HuB and HuD competed with HuR for binding to TERC and antagonized the function of HuR that was previously shown to enhance telomerase activity to promote cell growth. Our findings reveal a novel mechanism controlling telomerase activity in human neuroblastoma cells that involves a competition between HuR and the related, neural-specific proteins HuB and HuD.


Assuntos
Proteína Semelhante a ELAV 1/metabolismo , Proteína Semelhante a ELAV 2/metabolismo , Proteína Semelhante a ELAV 4/metabolismo , RNA/metabolismo , Telomerase/metabolismo , Linhagem Celular Tumoral , Senescência Celular , Proteína Semelhante a ELAV 1/antagonistas & inibidores , Humanos
12.
Nucleic Acids Res ; 49(5): 2655-2673, 2021 03 18.
Artigo em Inglês | MEDLINE | ID: mdl-33590101

RESUMO

Plasmids and temperate phages are key contributors to bacterial evolution. They are usually regarded as very distinct. However, some elements, termed phage-plasmids, are known to be both plasmids and phages, e.g. P1, N15 or SSU5. The number, distribution, relatedness and characteristics of these phage-plasmids are poorly known. Here, we screened for these elements among ca. 2500 phages and 12000 plasmids and identified 780 phage-plasmids across very diverse bacterial phyla. We grouped 92% of them by similarity of gene repertoires to eight defined groups and 18 other broader communities of elements. The existence of these large groups suggests that phage-plasmids are ancient. Their gene repertoires are large, the average element is larger than an average phage or plasmid, and they include slightly more homologs to phages than to plasmids. We analyzed the pangenomes and the genetic organization of each group of phage-plasmids and found the key phage genes to be conserved and co-localized within distinct groups, whereas genes with homologs in plasmids are much more variable and include most accessory genes. Phage-plasmids are a sizeable fraction of the sequenced plasmids (∼7%) and phages (∼5%), and could have key roles in bridging the genetic divide between phages and other mobile genetic elements.


Assuntos
Bactérias/genética , Bacteriófagos/genética , Plasmídeos/genética , Prófagos/genética , Acinetobacter/genética , Bases de Dados de Ácidos Nucleicos , Enterobacteriaceae/enzimologia , Enterobacteriaceae/genética , Genes Bacterianos , Telomerase/genética
13.
Mol Cell Biol ; 41(4)2021 03 24.
Artigo em Inglês | MEDLINE | ID: mdl-33526451

RESUMO

The nuclear and subnuclear compartmentalization of the telomerase-associated protein and H/ACA ribonucleoprotein component dyskerin is an important although incompletely understood aspect of H/ACA ribonucleoprotein function. Four SUMOylation sites were previously identified in the C-terminal nuclear/nucleolar localization signal (N/NoLS) of dyskerin. We found that a cytoplasmic localized C-terminal truncation variant of dyskerin lacking most of the C-terminal N/NoLS represents an under-SUMOylated variant of dyskerin compared to wild-type dyskerin. We demonstrate that mimicking constitutive SUMOylation of dyskerin using a SUMO3 fusion construct can drive nuclear accumulation of this variant and that the SUMO site K467 in this N/NoLS is particularly important for the subnuclear localization of dyskerin to the nucleolus in a mature H/ACA complex assembly- and SUMO-dependent manner. We also characterize a novel SUMO-interacting motif in the mature H/ACA complex component GAR1 that mediates the interaction between dyskerin and GAR1. Mislocalization of dyskerin, either in the cytoplasm or excluded from the nucleolus, disrupts dyskerin function and leads to reduced interaction of dyskerin with the telomerase RNA. These data indicate a role for dyskerin C-terminal N/NoLS SUMOylation in regulating the nuclear and subnuclear localization of dyskerin, which is essential for dyskerin function as both a telomerase-associated protein and as an H/ACA ribonucleoprotein.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Citoplasma/metabolismo , Ribonucleoproteínas Nucleolares Pequenas/metabolismo , Sumoilação/fisiologia , Núcleo Celular/metabolismo , Disceratose Congênita/genética , Disceratose Congênita/metabolismo , Humanos , Sinais de Localização Nuclear/genética , Proteínas Nucleares/metabolismo , RNA/metabolismo , Proteínas de Ligação a RNA/metabolismo , Telomerase/metabolismo
14.
Nat Rev Mol Cell Biol ; 22(4): 283-298, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33564154

RESUMO

The regulation of telomere length in mammals is crucial for chromosome end-capping and thus for maintaining genome stability and cellular lifespan. This process requires coordination between telomeric protein complexes and the ribonucleoprotein telomerase, which extends the telomeric DNA. Telomeric proteins modulate telomere architecture, recruit telomerase to accessible telomeres and orchestrate the conversion of the newly synthesized telomeric single-stranded DNA tail into double-stranded DNA. Dysfunctional telomere maintenance leads to telomere shortening, which causes human diseases including bone marrow failure, premature ageing and cancer. Recent studies provide new insights into telomerase-related interactions (the 'telomere replisome') and reveal new challenges for future telomere structural biology endeavours owing to the dynamic nature of telomere architecture and the great number of structures that telomeres form. In this Review, we discuss recently determined structures of the shelterin and CTC1-STN1-TEN1 (CST) complexes, how they may participate in the regulation of telomere replication and chromosome end-capping, and how disease-causing mutations in their encoding genes may affect specific functions. Major outstanding questions in the field include how all of the telomere components assemble relative to each other and how the switching between different telomere structures is achieved.


Assuntos
Cromatina/metabolismo , Proteínas de Ligação a Telômeros/metabolismo , Telômero/metabolismo , Animais , Cromossomos/metabolismo , DNA/metabolismo , Humanos , Telomerase/metabolismo
15.
Clinics (Sao Paulo) ; 76: e2432, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33567048

RESUMO

OBJECTIVES: Telomeres are a terminal "DNA cap" that prevent chromosomal fusion and degradation. However, aging is inherent to life, and so is the loss of terminal sequences. Telomerase is a specialized reverse transcriptase encoded by self-splicing introns that counteract chromosome erosion. Telomerase activity is observed during early embryonic development, but after the blastocyst stage, the expression of telomerase reduces. The consequences of either insufficient or unrestrained telomerase activity underscore the importance of ongoing studies aimed at elucidating the regulation of telomerase activity in humans. In the present study, we aimed to standardize a simplified telomerase repeat-amplification protocol (TRAP) assay to detect telomerase activity in unstimulated and PHA-stimulated mononuclear cells. METHODS AND RESULTS: Our optimized qPCR-based can efficiently evaluate telomerase activity. Quantification of protein and DNA between unstimulated and PHA-stimulated peripheral blood mononuclear cells revealed cellular activation and cell-cycle entry. The assay also showed that relative telomerase activity is significantly different between these two conditions, supporting the applicability of the assay. Furthermore, our findings corroborated that telomerase activity decreases with age. CONCLUSIONS: Telomeres and telomerase are implicated in aging and development of chronic diseases and cancer; however, difficulty in accessing commercial kits to investigate these aspects is a critical constraint in health surveillance studies. Our optimized assay was successfully used to differentiate telomerase activity between unstimulated and stimulated cells, clearly showing the reactivation of telomerase upon cell activation. This assay is affordable, reproducible, and can be executed in resource-limited settings.


Assuntos
Neoplasias , Telomerase , Envelhecimento , Doença Crônica , Análise Custo-Benefício , Feminino , Humanos , Leucócitos Mononucleares/metabolismo , Gravidez , Telomerase/genética , Telomerase/metabolismo
16.
Artigo em Inglês | MEDLINE | ID: mdl-33567728

RESUMO

BACKGROUND: A burgeoning literature has found relationships between telomere length, telomerase activity, and human health and longevity. Although some research links a history of childhood adversity with shortened telomere length, our review found no prior research on the relationship between child maltreatment history and telomerase activity in adulthood. We hypothesized a negative relationship between child maltreatment and telomerase activity and hypothesized that the association would be moderated by sex. METHODS: These relationships were tested on a sample of 262 Hong Kong Chinese adults (200 females versus 62 males) with mild to moderate depression. RESULTS: Counterintuitively, emotional abuse was positively associated with telomerase activity, while other maltreatment types were non-significant. The positive relationship between emotional abuse and telomerase activity was significantly moderated by the sex of the participant. CONCLUSIONS: We advance two possible explanations for this finding (1) a culturally informed resilience explanation and (2) a homeostatic complexity explanation. The two explanations are not mutually exclusive. This trial is registered under Hong Kong Clinical Trial Register number HKCTR-1929. SIGNIFICANCE STATEMENT: Emotional abuse was significantly positively associated with telomerase activity. There are at least two non-mutually exclusive explanations for the findings. Simply put, either (1) in the cultural context of Hong Kong emotional abuse was not a risk factor, and/or (2) the conceptualization of telomerase activity as a straightforward indicator of longevity is overly simplistic. The first story we might term a "resilience explanation" while the second we might call a "homeostatic complexity" story.


Assuntos
Maus-Tratos Infantis , Telomerase , Adulto , Criança , Feminino , Hong Kong , Humanos , Masculino , Inquéritos e Questionários , Telômero , Encurtamento do Telômero
17.
J Cancer Res Clin Oncol ; 147(4): 1007-1017, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33547950

RESUMO

The TERT promoter (pTERT) mutations, C228T and C250T, play a significant role in malignant transformation by telomerase activation, oncogenesis and immortalisation of cells. C228T and C250T are emerging as important biomarkers in many cancers including glioblastoma multiforme (GBM), where the prevalence of these mutations is as high as 80%. Additionally, the rs2853669 single nucleotide polymorphism (SNP) may cooperate with these pTERT mutations in modulating progression and overall survival in GBM. Using liquid biopsies, pTERT mutations, C228T and C250T, and other clinically relevant biomarkers can be easily detected with high precision and sensitivity, facilitating longitudinal analysis throughout therapy and aid in cancer patient management.In this review, we explore the potential for pTERT mutation analysis, via liquid biopsy, for its potential use in personalised cancer therapy. We evaluate the relationship between pTERT mutations and other biomarkers as well as their potential clinical utility in early detection, prognostication, monitoring of cancer progress, with the main focus being on brain cancer.


Assuntos
Biomarcadores Tumorais/genética , Neoplasias Encefálicas/patologia , Glioma/patologia , Mutação , Telomerase/genética , Neoplasias Encefálicas/genética , Neoplasias Encefálicas/terapia , Glioma/genética , Glioma/terapia , Humanos , Prognóstico
18.
J Cancer Res Clin Oncol ; 147(4): 1125-1135, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33635430

RESUMO

PURPOSE: Penile carcinoma is a rare malignant neoplasm with a largely unknown molecular pathogenesis. Telomerase reverse transcriptase promoter (TERT-p) mutations have been detected in several types of human malignancies. The aim of this study was to investigate the presence of TERT-p mutations in penile squamous cell carcinomas (SCCs) and their associations with clinicopathologic features. METHODS: In this retrospective study, Sanger sequencing was performed to detect TERT-p mutations in formalin-fixed paraffin-embedded tissue samples from 37 patients with penile SCC, 16 patients with cutaneous SCC, and 4 patients with non-neoplastic penile/skin tissue. The expression of p16INK4a and Ki-67 was investigated via immunohistochemistry. Associations of TERT-p mutation with clinicopathological factors, immunohistochemical results, and clinical outcome were statistically analyzed. RESULTS: Recurrent TERT-p mutations were identified in 18 out of 37 (48.6%) penile SCCs, including all 3 carcinoma in situ cases. TERT-p mutations were significantly more frequent in non-human papilloma virus (HPV)-related penile SCC types than in non-HPV-related penile SCC based on both histologic classification and p16INK4a immunoreactivity. Furthermore, TERT-p mutation was associated with a low histologic grade, low mitotic count, absence of necrosis, low Ki-67/MIB-1 labeling index, and absence of lymph node or distant metastasis. CONCLUSION: Our study shows TERT-p mutations are the most frequent somatic mutations in penile SCC. In addition, TERT-p mutations are far more frequent in non-HPV-related penile SCC than in HPV-related penile SCC, indicating TERT-p mutations may have a role in tumorigenesis distinct from HPV-related penile SCC.


Assuntos
Biomarcadores Tumorais/genética , Carcinoma de Células Escamosas/patologia , Mutação , Infecções por Papillomavirus/complicações , Neoplasias Penianas/patologia , Regiões Promotoras Genéticas , Telomerase/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores Tumorais/metabolismo , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/virologia , Estudos de Casos e Controles , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidor p16 de Quinase Dependente de Ciclina/metabolismo , Feminino , Seguimentos , Humanos , Antígeno Ki-67/genética , Antígeno Ki-67/metabolismo , Masculino , Pessoa de Meia-Idade , Papillomaviridae/isolamento & purificação , Infecções por Papillomavirus/virologia , Neoplasias Penianas/genética , Neoplasias Penianas/virologia , Prognóstico , Estudos Retrospectivos , Taxa de Sobrevida
19.
Nat Commun ; 12(1): 1097, 2021 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-33597549

RESUMO

Telomeres are part of a highly refined system for maintaining the stability of linear chromosomes. Most telomeres rely on simple repetitive sequences and telomerase enzymes to protect chromosomal ends; however, in some species or telomerase-defective situations, an alternative lengthening of telomeres (ALT) mechanism is used. ALT mainly utilises recombination-based replication mechanisms and the constituents of ALT-based telomeres vary depending on models. Here we show that mouse telomeres can exploit non-telomeric, unique sequences in addition to telomeric repeats. We establish that a specific subtelomeric element, the mouse template for ALT (mTALT), is used for repairing telomeric DNA damage as well as for composing portions of telomeres in ALT-dependent mouse embryonic stem cells. Epigenomic and proteomic analyses before and after ALT activation reveal a high level of non-coding mTALT transcripts despite the heterochromatic nature of mTALT-based telomeres. After ALT activation, the increased HMGN1, a non-histone chromosomal protein, contributes to the maintenance of telomere stability by regulating telomeric transcription. These findings provide a molecular basis to study the evolution of new structures in telomeres.


Assuntos
Células-Tronco Embrionárias Murinas/metabolismo , Sequências Repetitivas de Ácido Nucleico/genética , Telomerase/genética , Homeostase do Telômero/genética , Telômero/genética , Animais , Proteínas de Ligação a DNA/genética , Epigenômica/métodos , Células HEK293 , Humanos , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Células-Tronco Embrionárias Murinas/citologia , Proteômica/métodos , Análise de Sequência de RNA/métodos , Análise de Célula Única/métodos , Telomerase/metabolismo , Telômero/enzimologia , Fatores de Transcrição/genética
20.
Mol Cell ; 81(8): 1816-1829.e5, 2021 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-33639094

RESUMO

Alternative lengthening of telomeres (ALT) is a recombination process that maintains telomeres in the absence of telomerase and helps cancer cells to survive. Yeast has been used as a robust model of ALT; however, the inability to determine the frequency and structure of ALT survivors hinders understanding of the ALT mechanism. Here, using population and molecular genetics approaches, we overcome these problems and demonstrate that contrary to the current view, both RAD51-dependent and RAD51-independent mechanisms are required for a unified ALT survivor pathway. This conclusion is based on the calculation of ALT frequencies, as well as on ultra-long sequencing of ALT products that revealed hybrid sequences containing features attributed to both recombination pathways. Sequencing of ALT intermediates demonstrates that recombination begins with Rad51-mediated strand invasion to form DNA substrates that are matured by a Rad51-independent ssDNA annealing pathway. A similar unified ALT pathway may operate in other organisms, including humans.


Assuntos
Saccharomyces cerevisiae/genética , Homeostase do Telômero/genética , Telômero/genética , DNA/genética , Rad51 Recombinase/genética , Recombinação Genética/genética , Telomerase/genética
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...