Telomere Length Dynamics and the Evolution of Cancer Genome Architecture

Circulating TERT serves as the novel diagnostic and prognostic biomarker for the resectable NSCLC

BACKGROUND

Telomerase reverse transcriptase (TERT) is a catalytic subunit of telomerase and required for cancer development. This study aims to reveal its clinical utility for diagnosis and prognosis of resectable NSCLC.

METHODS

TERT was quantitatively evaluated by the enzyme-linked immunosorbent assay (ELISA) from 69 patients before and after the surgery. The prognostic value was evaluated by disease-free survival (DFS) and overall survival (OS).

RESULTS

Circulating TERT in NSCLC patients were significantly higher than that in the healthy group, possessing the AUC of 0.90. Importantly, TERT change between pre- and post- operation was significantly correlated with OS and DFS (p = 0.022, p = 0.046 respectively), acted as the independent prognostic factors for DFS and OS, indicating it can serve as the promising diagnostic and prognostic biomarker for resectable non-small cell lung cancer (NSCLC).

CONCLUSIONS

TERT change between pre- and post- resection can serve as the promising biomarker for prognosis of resectable NSCLC.

Connecting the Dots: Telomere Shortening and Rheumatic Diseases

Telomeres, repetitive sequences located at the extremities of chromosomes, play a pivotal role in sustaining chromosomal stability. Telomerase is a complex enzyme that can elongate telomeres by appending telomeric repeats to chromosome ends and acts as a critical factor in telomere dynamics. The gradual shortening of telomeres over time is a hallmark of cellular senescence and cellular death. Notably, telomere shortening appears to result from the complex interplay of two primary mechanisms: telomere shelterin complexes and telomerase activity. The intricate interplay of genetic, environmental, and lifestyle influences can perturb telomere replication, incite oxidative stress damage, and modulate telomerase activity, collectively resulting in shifts in telomere length. This age-related process of telomere shortening plays a considerable role in various chronic inflammatory and oxidative stress conditions, including cancer, cardiovascular disease, and rheumatic disease. Existing evidence has shown that abnormal telomere shortening or telomerase activity abnormalities are present in the pathophysiological processes of most rheumatic diseases, including different disease stages and cell types. The impact of telomere shortening on rheumatic diseases is multifaceted. This review summarizes the current understanding of the link between telomere length and rheumatic diseases in clinical patients and examines probable telomere shortening in peripheral blood mononuclear cells and histiocytes. Therefore, understanding the intricate interaction between telomere shortening and various rheumatic diseases will help in designing personalized treatment and control measures for rheumatic disease.

Gradual telomere shortening in the tumorigenesis of pancreatic and hepatic mucinous cystic neoplasms

Mucinous cystic neoplasm (MCN) is one of the precursor lesions of pancreatic ductal adenocarcinoma and intrahepatic cholangiocarcinoma. The aim of this study is to examine the presence of short telomeres in promoting the tumorigenesis of MCN by measuring telomere lengths in distinct components of MCN, including the mucinous lining epithelium, non-mucinous lining epithelium, and ovarian-type stroma. A total of 45 patients with MCN (30 pancreatic and 15 hepatic cases) were obtained. Quantitative telomere-specific fluorescent in situ hybridization was performed to measure the telomere length of specific cell types within MCNs, including mucinous lining epithelium, non-mucinous lining epithelium, and ovarian-type stroma, as well as normal ductal epithelium and adenocarcinoma. Relative telomere lengths tended to decrease between normal ductal epithelium, ovarian-type stroma, non-mucinous lining epithelium, mucinous lining epithelium, and adenocarcinoma regardless of the involved organs. Among the analyzed cell types, relative telomere lengths were significantly different between normal ductal epithelium (3.31 ± 0.78), ovarian-type stroma (2.90 ± 0.93), non-mucinous lining epithelium (2.84 ± 0.79), mucinous lining epithelium (2.49 ± 0.93), and adenocarcinoma (1.19 ± 0.59), respectively (P < 0.001, mixed-effects model). As expected, no difference in relative telomere lengths was observed between normal ductal epithelium and ovarian-type stroma; however, significant differences were observed in pair-wise comparisons between ovarian-type stroma vs. non-mucinous lining epithelium (P = 0.001), non-mucinous lining epithelium vs. mucinous lining epithelium (P = 0.005), and mucinous lining epithelium vs. adenocarcinoma (P < 0.001). These findings suggest gradual telomere shortening occurs in the tumorigenesis of MCN, which may have important implications for the progression of this disease.

Physical Activity and Epigenetic Aging in Breast Cancer Treatment

Biological age, reflecting the cumulative damage in the body over a lifespan, is a dynamic measure more indicative of individual health than chronological age. Accelerated aging, when biological age surpasses chronological age, is implicated in poorer clinical outcomes, especially for breast cancer (BC) survivors undergoing treatments. This preliminary study investigates the impact of a 16-week online supervised physical activity (PA) intervention on biological age in post-surgery female BC patients. Telomere length was measured using qPCR, and the ELOVL2-based epigenetic clock was assessed via DNA methylation pyrosequencing of the ELOVL2 promoter region. Telomere length remained unchanged, but the ELOVL2 epigenetic clock indicated a significant decrease in biological age in the PA group, suggesting the potential of PA interventions to reverse accelerated aging processes in BC survivors. The exercise group showed improved cardiovascular fitness, highlighting PA's health impact. Finally, the reduction in biological age, as measured by the ELOVL2 epigenetic clock, was significantly associated with improvements in cardiovascular fitness and handgrip strength, supporting improved recovery. Epigenetic clocks can potentially assess health status and recovery progress in BC patients, identifying at-risk individuals in clinical practice. This study provides potential and valuable insights into how PA benefits BC survivors' health, supporting the immediate benefits of a 16-week exercise intervention in mitigating accelerated aging. The findings could suggest a holistic approach to improving the health and recovery of post-surgery BC patients.

Reproductive Ageing: Metabolic contribution to age-related chromosome missegregation in mammalian oocytes

In brief

Chromosome missegregation and declining energy metabolism are considered to be unrelated features of oocyte ageing that contribute to poor reproductive outcomes. Given the bioenergetic cost of chromosome segregation, we propose here that altered energy metabolism during ageing may be an underlying cause of age-related chromosome missegregation and aneuploidy.

Abstract

Advanced reproductive age in women is a major cause of infertility, miscarriage and congenital abnormalities. This is principally caused by a decrease in oocyte quality and developmental competence with age. Oocyte ageing is characterised by an increase in chromosome missegregation and aneuploidy. However, the underlying mechanisms of age-related aneuploidy have not been fully elucidated and are still under active investigation. In addition to chromosome missegregation, oocyte ageing is also accompanied by metabolic dysfunction. In this review, we integrate old and new perspectives on oocyte ageing, chromosome segregation and metabolism in mammalian oocytes and make direct links between these processes. We consider age-related alterations to chromosome segregation machinery, including the loss of cohesion, microtubule stability and the integrity of the spindle assembly checkpoint. We focus on how metabolic dysfunction in the ageing oocyte disrupts chromosome segregation machinery to contribute to and exacerbate age-related aneuploidy. More specifically, we discuss how mitochondrial function, ATP production and the generation of free radicals are altered during ageing. We also explore recent developments in oocyte metabolic ageing, including altered redox reactions (NAD+ metabolism) and the interactions between oocytes and their somatic nurse cells. Throughout the review, we integrate the mechanisms by which changes in oocyte metabolism influence age-related chromosome missegregation.

Targeting Telomere Dynamics as an Effective Approach for the Development of Cancer Therapeutics

Telomere is a protective structure located at the end of chromosomes of eukaryotes, involved in maintaining the integrity and stability of the genome. Telomeres play an essential role in cancer progression; accordingly, targeting telomere dynamics emerges as an effective approach for the development of cancer therapeutics. Targeting telomere dynamics may work through multifaceted molecular mechanisms; those include the activation of anti-telomerase immune responses, shortening of telomere lengths, induction of telomere dysfunction and constitution of telomerase-responsive drug release systems. In this review, we summarize a wide variety of telomere dynamics-targeted agents in preclinical studies and clinical trials, and reveal their promising therapeutic potential in cancer therapy. As shown, telomere dynamics-active agents are effective as anti-cancer chemotherapeutics and immunotherapeutics. Notably, these agents may display efficacy against cancer stem cells, reducing cancer stem levels. Furthermore, these agents can be integrated with the capability of tumor-specific drug delivery by the constitution of related nanoparticles, antibody drug conjugates and HSA-based drugs.

Effects of SETD2 on telomere length and malignant transformation property of Met-5A after one-month crocidolite exposure

Crocidolite is a carcinogen contributing to the pathogenesis of malignant mesothelioma. This study aimed to characterize the possible telomere-related events mediating the malignant transformation of mesothelial cells with and without SETD2 under crocidolite exposure. The crocidolite concentration resulting in 90% viable SETD2 knockout Met-5A (Met-5ASETD2-KO) and Met-5A were estimated to be 0.71 μg/cm2 and 1.8 μg/cm2, respectively, during 72 h of exposure, which was further employed in chronical crocidolite exposure during a 72 h exposure interval per time up to 1 month. Chronical crocidolite-exposed Met-5ASETD2-KO (chronical Cro-Met-5ASETD2-KO) had higher colony formation and increased telomerase reverse transcriptase (TERT) protein levels than chronical crocidolite-exposed Met-5A (chronical Cro-Met-5A) and Met-5ASETD2-KO. Chronical Cro-Met-5ASETD2-KO had longer telomere length (TL) than chronical Cro-Met-5A, although there were no changes in TL for either chronical Cro-Met-5A or chronical Cro-Met-5ASETD2-KO compared with their corresponding cells without crocidolite exposure. BIBR 1532, an inhibitor targeting TERT, partially reduced colony formation and TL for chronical Cro-Met-5ASETD2-KO, while BIBR 1532 reduced TL but had no effect on colony formation for chronical Cro-Met-5A. Therefore, SETD2 deficient mesothelial cells are susceptible to malignant transformation during chronical crocidolite exposure, and TERT-dependent TL modification likely partially drives SETD2 loss-mediated early onset of mesothelial malignant transformation.

Biological clocks as age estimation markers in animals: a systematic review and meta-analysis

Various biological attributes associated with individual fitness in animals change predictably over the lifespan of an organism. Therefore, the study of animal ecology and the work of conservationists frequently relies upon the ability to assign animals to functionally relevant age classes to model population fitness. Several approaches have been applied to determining individual age and, while these methods have proved useful, they are not without limitations and often lack standardisation or are only applicable to specific species. For these reasons, scientists have explored the potential use of biological clocks towards creating a universal age-determination method. Two biological clocks, tooth layer annulation and otolith layering have found universal appeal. Both methods are highly invasive and most appropriate for post-mortem age-at-death estimation. More recently, attributes of cellular ageing previously explored in humans have been adapted to studying ageing in animals for the use of less-invasive molecular methods for determining age. Here, we review two such methods, assessment of methylation and telomere length, describing (i) what they are, (ii) how they change with age, and providing (iii) a summary and meta-analysis of studies that have explored their utility in animal age determination. We found that both attributes have been studied across multiple vertebrate classes, however, telomere studies were used before methylation studies and telomere length has been modelled in nearly twice as many studies. Telomere length studies included in the review often related changes to stress responses and illustrated that telomere length is sensitive to environmental and social stressors and, in the absence of repair mechanisms such as telomerase or alternative lengthening modes, lacks the ability to recover. Methylation studies, however, while also detecting sensitivity to stressors and toxins, illustrated the ability to recover from such stresses after a period of accelerated ageing, likely due to constitutive expression or reactivation of repair enzymes such as DNA methyl transferases. We also found that both studied attributes have parentally heritable features, but the mode of inheritance differs among taxa and may relate to heterogamy. Our meta-analysis included more than 40 species in common for methylation and telomere length, although both analyses included at least 60 age-estimation models. We found that methylation outperforms telomere length in terms of predictive power evidenced from effect sizes (more than double that observed for telomeres) and smaller prediction intervals. Both methods produced age correlation models using similar sample sizes and were able to classify individuals into young, middle, or old age classes with high accuracy. Our review and meta-analysis illustrate that both methods are well suited to studying age in animals and do not suffer significantly from variation due to differences in the lifespan of the species, genome size, karyotype, or tissue type but rather that quantitative method, patterns of inheritance, and environmental factors should be the main considerations. Thus, provided that complex factors affecting the measured trait can be accounted for, both methylation and telomere length are promising targets to develop as biomarkers for age determination in animals.

Big data analysis identified a telomere-related signature predicting the prognosis and drug sensitivity in lung adenocarcinoma

Telomeres exert a critical role in chromosome stability and aberrant regulation of telomerase may result in telomeres dysfunction and genomic instability, which are involved in the occurrence of cancers. However, limited studies have been performed to fully clarify the immune infiltration and clinical significance of telomeres-related genes (TRGs) in lung adenocarcinoma (LUAD). The number of clusters of LUAD was determined by consensus clustering analysis. The prognostic signature was constructed and verified using TCGA and GSE42127 dataset with Least Absolute Shrinkage and Selection Operator cox regression analysis. The correlation between different clusters and risk-score and drug therapy response was analyzed using TIDE and IMvigor210 dataset. Using several miRNA and lncRNA related databases, we constructed a lncRNA-miRNA-mRNA regulatory axis. We identified 2 telomeres-related clusters in LUAD, which had distinct differences in prognostic stratification, TMB score, TIDE score, immune characteristics and signal pathways and biological effects. A prognostic model was developed based on 21 TRGs, which had a better performance in risk stratification and prognosis prediction compared with other established models. TRGs-based risk score could serve as an independent risk factor for LUAD. Survival prediction nomogram was also developed to promote the clinical use of TRGs risk score. Moreover, LUAD patients with high risk score had a high TMB score, low TIDE score and IC50 value of common drugs, suggesting that high risk score group might benefit from receiving immunotherapy, chemotherapy and target therapy. We also developed a lncRNA KCNQ1QT1/miR-296-5p/PLK1 regulatory axis. Our study identified 2 telomeres-related clusters and a prognostic model in LUAD, which could be helpful for risk stratification, prognosis prediction and treatment approach selection.

Regulation and function of R-loops at repetitive elements

R-loops are atypical, three-stranded nucleic acid structures that contain a stretch of RNA:DNA hybrids and an unpaired, single stranded DNA loop. R-loops are physiological relevant and can act as regulators of gene expression, chromatin structure, DNA damage repair and DNA replication. However, unscheduled and persistent R-loops are mutagenic and can mediate replication-transcription conflicts, leading to DNA damage and genome instability if left unchecked. Detailed transcriptome analysis unveiled that 85% of the human genome, including repetitive regions, hold transcriptional activity. This anticipates that R-loops management plays a central role for the regulation and integrity of genomes. This function is expected to have a particular relevance for repetitive sequences that make up to 75% of the human genome. Here, we review the impact of R-loops on the function and stability of repetitive regions such as centromeres, telomeres, rDNA arrays, transposable elements and triplet repeat expansions and discuss their relevance for associated pathological conditions.

Decoding Cancer Evolution: Integrating Genetic and Non-Genetic Insights

The development of cancer begins with cells transitioning from their multicellular nature to a state akin to unicellular organisms. This shift leads to a breakdown in the crucial regulators inherent to multicellularity, resulting in the emergence of diverse cancer cell subpopulations that have enhanced adaptability. The presence of different cell subpopulations within a tumour, known as intratumoural heterogeneity (ITH), poses challenges for cancer treatment. In this review, we delve into the dynamics of the shift from multicellularity to unicellularity during cancer onset and progression. We highlight the role of genetic and non-genetic factors, as well as tumour microenvironment, in promoting ITH and cancer evolution. Additionally, we shed light on the latest advancements in omics technologies that allow for in-depth analysis of tumours at the single-cell level and their spatial organization within the tissue. Obtaining such detailed information is crucial for deepening our understanding of the diverse evolutionary paths of cancer, allowing for the development of effective therapies targeting the key drivers of cancer evolution.

A non-genetic switch triggers alternative telomere lengthening and cellular immortalization in ATRX deficient cells

Alternative Lengthening of Telomeres (ALT) is an aberrant DNA recombination pathway which grants replicative immortality to approximately 10% of all cancers. Despite this high prevalence of ALT in cancer, the mechanism and genetics by which cells activate this pathway remain incompletely understood. A major challenge in dissecting the events that initiate ALT is the extremely low frequency of ALT induction in human cell systems. Guided by the genetic lesions that have been associated with ALT from cancer sequencing studies, we genetically engineered primary human pluripotent stem cells to deterministically induce ALT upon differentiation. Using this genetically defined system, we demonstrate that disruption of the p53 and Rb pathways in combination with ATRX loss-of-function is sufficient to induce all hallmarks of ALT and results in functional immortalization in a cell type-specific manner. We further demonstrate that ALT can be induced in the presence of telomerase, is neither dependent on telomere shortening nor crisis, but is rather driven by continuous telomere instability triggered by the induction of differentiation in ATRX-deficient stem cells.

Antitumor efficacy of a recombinant EGFR-targeted fusion protein conjugate that induces telomere shortening and telomerase downregulation

OBJECTIVE

To prepare a recombinant EGFR-targeted fusion protein drug conjugate acting on telomere and telomerase; and evaluate its antitumor efficacy.

METHODS

We prepared a recombinant fusion protein Fv-LDP-D3 which consists of the Fv fragment of an anti-EGFR monoclonal antibody (MAb), the apoprotein of lidamycin (LDP), and the third domain (D3) of human serum albumin (HSA); then generated the conjugate Fv-LDP-D3∼AE by integrating the active enediyne chomophore (AE) of lidamycin. Accordingly, in vitro and in vivo experiments were performed.

RESULTS

As shown, Fv-LDP-D3 specifically bound to EGFR highly-expressing cancer cells and intensely entered K-Ras mutant cells via enhanced macropinocytosis. By in vivo imaging, Fv-LDP-D3 displayed intense accumulation and persistent retention in tumor-site. Furthermore, the conjugate Fv-LDP-D3∼AE displayed highly potent cytotoxicity to cancer cells with IC₅₀ at 0.1 nM level. The conjugate induced telomere shortening and downregulation of telomerase and EGFR pathway related proteins. Fv-LDP-D3∼AE exhibited prominent antitumor efficacy against human colorectal cancer xenograft accompanying with significant increase of serum IFN-β in athymic mice.

CONCLUSION

The recombinant fusion protein conjugate that exhibits the capability of tumor-targeting drug delivery can induce telomere shortening and telomerase downregulation. The investigation may lay the foundation for the development of MAb-HSA domain-based fusion protein drug conjugates.

Telomeres, the loop tying cancer to organismal life-histories

Recent developments in telomere and cancer evolutionary ecology demonstrate a very complex relationship between the need of tissue repair and controlling the emergence of abnormally proliferating cells. The trade-off is balanced by natural and sexual selection and mediated via both intrinsic and environmental factors. Here, we explore the effects of telomere-cancer dynamics on life history traits and strategies as well as on the cumulative effects of genetic and environmental factors. We show that telomere-cancer dynamics constitute an incredibly complex and multifaceted process. From research to date, it appears that the relationship between telomere length and cancer risk is likely nonlinear with good evidence that both (too) long and (too) short telomeres can be associated with increased cancer risk. The ability and propensity of organisms to respond to the interplay of telomere dynamics and oncogenic processes, depends on the combination of its tissue environments, life history strategies, environmental challenges (i.e., extreme climatic conditions), pressure by predators and pollution, as well as its evolutionary history. Consequently, precise interpretation of telomere-cancer dynamics requires integrative and multidisciplinary approaches. Finally, incorporating information on telomere dynamics and the expression of tumour suppressor genes and oncogenes could potentially provide the synergistic overview that could lay the foundations to study telomere-cancer dynamics at ecosystem levels.

Physical Activity on Telomere Length as a Biomarker for Aging: A Systematic Review

Background

Overall life expectancy continues to rise, approaching 80 years of age in several developed countries. However, healthy life expectancy lags far behind, which has, in turn, contributed to increasing costs in healthcare. One way to improve health and attenuate the socio-economic impact of an aging population is to increase overall fitness through physical activity. Telomere attrition or shortening is a well-known molecular marker in aging. As such, several studies have focused on whether exercise influences health and aging through telomere biology. This systematic review examines the recent literature on the effect of physical activity on telomere length (TL) and/or telomerase activity as molecular markers of aging.

Methods

A focused search was performed in the databases PubMed and Web of Science for retrieving relevant articles over the past ten years. The search contained the following keywords: exercise, sport, physical activity, fitness, sedentary, physical inactivity, telomere, telomere length, t/s ratio, and telomerase. PRISMA guidelines for systematic reviews were observed.

Results

A total of 43 articles were identified and categorized into randomized controlled trials (RCT), observational or interventional studies. RCTs (n = 8) showed inconsistent findings of increased TL length with physical activity in, e.g. obese, post-menopausal women. In comparison with a predominantly sedentary lifestyle, observational studies (n = 27) showed significantly longer TL with exercise of moderate to vigorous intensity; however, there was no consensus on the duration and type of physical activity and training modality. Interventional studies (n = 8) also showed similar findings of significantly longer TL prior to exercise intervention; however, these studies had smaller numbers of enrolled participants (mostly of high-performance athletes), and the physical activities covered a range of exercise intensities and duration. Amongst the selected studies, aerobic training of moderate to vigorous intensity is most prevalent. For telomere biology analysis, TL was determined mainly from leukocytes using qPCR. In some cases, especially in RCT and interventional studies, different sample types such as saliva, sperm, and muscle biopsies were analyzed; different leukocyte cell types and potential genetic markers in regulating telomere biology were also investigated.

Conclusions

Taken together, physical activity with regular aerobic training of moderate to vigorous intensity appears to help preserve TL. However, the optimal intensity, duration of physical activity, as well as type of exercise still need to be further elucidated. Along with TL or telomerase activity, participants’ fitness level, the type of physical activity, and training modality should be assessed at different time points in future studies, with the plan for long-term follow-up. Reducing the amount of sedentary behavior may have a positive effect of preserving and increasing TL. Further molecular characterization of telomere biology in different cell types and tissues is required in order to draw definitive causal conclusions on how physical activity affects TL and aging.

Systemic Sclerosis Association with Malignancy

The association of systemic sclerosis (SSc) and cancer is well known from several decades suggesting common genetic and environmental risk factors involved in the development of both diseases. Immunosuppressive drugs widely used in SSc may increase the risk of cancer occurrence and different SSc clinical and serological features identify patients at major risk to develop malignancy. In this context, among serological features, presence of anti-RNA polymerase III and anti-topoisomerase I autoantibodies seems to increase cancer frequency in SSc patients (particularly lung and breast cancers). Lung fibrosis and a long standing SSc pulmonary involvement have been largely proposed as lung cancer risk factors, and the exposure to cyclophosphamide and an upper gastrointestinal involvement have been traditionally linked to bladder and oesophagus cancers, respectively. Furthermore, immune checkpoint inhibitors used for cancer therapy can induce immune-related adverse events, which are more frequent and severe in patients with pre-existing autoimmune diseases such as SSc. The strong association between SSc and cancer occurrence steers clinicians to carefully survey SSc patients performing periodical malignancy screening. In the present review, the most relevant bilateral relationships between SSc and cancer will be addressed.

Tieing together loose ends: telomere instability in cancer and aging

Telomere maintenance is essential for maintaining genome integrity in both normal and cancer cells. Without functional telomeres, chromosomes lose their protective structure and undergo fusion and breakage events that drive further genome instability, including cell arrest or death. One means by which this loss can be overcome in stem cells and cancer cells is via re-addition of G-rich telomeric repeats by the telomerase reverse transcriptase (TERT). During aging of somatic tissues, however, insufficient telomerase expression leads to a proliferative arrest called replicative senescence, which is triggered when telomeres reach a critically short threshold that induces a DNA damage response. Cancer cells express telomerase but do not entirely escape telomere instability as they often possess short telomeres; hence there is often selection for genetic alterations in the TERT promoter that result in increased telomerase expression. In this review, we discuss our current understanding of the consequences of telomere instability in cancer and aging, and outline the opportunities and challenges that lie ahead in exploiting the reliance of cells on telomere maintenance for preserving genome stability.

Mediation Effect of Platelet Traits on Associations of Central Obesity with Aging Biomarkers in Rural Adults of Henan, China

Background: To assess the associations of platelet traits and obesity indices with aging biomarkers (telomere length (TL) and mitochondrial DNA copy number (mtDNA-CN)). Methods: A cross-sectional study was performed among 5091 rural Chinese adults. Obesity indices (waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR)) and platelet traits (plateletcrit (PCT), platelet large cell ratio (P-LCR), mean platelet volume (MPV) and platelet distribution width (PDW)) were collected by physical examination. The aging biomarkers were determined by quantitative real-time polymerase chain reaction. Generalized linear regression models and mediation analysis were applied to explore the relationships between platelet traits, obesity indices, and aging biomarkers. Results: The mean age of the participants was 56 years (range: 18–79). Each one-unit increment in WC, WHR and WHtR were related to a 0.316 (95% confidence interval (CI): −0.437, −0.196), 0.323 (95% CI: −0.513, −0.134) and 0.277 (95% CI: −0.400, −0.153) decrease in relative TL; or a 0.102 (95% CI: −0.197, −0.007), 0.109 (95% CI: −0.258, −0.041) and 0.101 (95% CI: −0.199, −0.004) decrease in relative mtDNA-CN. The proportions of obesity indices with aging biomarkers mediated by platelet indices ranged from 2.85% to 10.10%. Conclusions: Increased central obesity indices in relation to shortened relative TL or decreased mtDNA-CN were mediated by platelet traits, indicating that obesity in association with the accelerated aging process may be partially attributable to abnormal platelet activity.

Congenital Aneuploidy in Klinefelter Syndrome with B-Cell Acute Lymphoblastic Leukemia Might Be Associated with Chromosomal Instability and Reduced Telomere Length

Simple Summary

Klinefelter syndrome (KS) is a rare congenital aneuploidy characterized by inherited gain of one X chromosome (XXY). KS is associated with higher susceptibility to the development of cancer. Somatic acquired chromosomal aberrations and chromosomal instability are hallmarks of cancer and leukemia but little is known about the cellular mechanisms involved. The conducted research aimed to identify genomic mechanisms involved in chromosomal evolution mechanisms important for leukemic development. In the leukemic blasts of a patient with KS and B-cell acute lymphoblastic leukemia (B-ALL), we identified additional acquired chromosomal aberration and a significant reduction in the length of the chromosomal ends, i.e., telomeres. A literature review of KS patients with B-ALL revealed that the majority of these patients had acquired two or more additional chromosomal aberrations at B-ALL diagnosis. These data indicate that enhanced reduction in telomere length might be associated with chromosomal instability and may serve as a future target for therapy or prevention.

Abstract

Rare congenital aneuploid conditions such as trisomy 13, trisomy 18, trisomy 21 and Klinefelter syndrome (KS, 47,XXY) are associated with higher susceptibility to developing cancer compared with euploid genomes. Aneuploidy frequently co-exists with chromosomal instability, which can be viewed as a “vicious cycle” where aneuploidy potentiates chromosomal instability, leading to further karyotype diversity, and in turn, paving the adaptive evolution of cancer. However, the relationship between congenital aneuploidy per se and tumor initiation and/or progression is not well understood. We used G-banding analysis, array comparative genomic hybridization analysis and quantitative fluorescence in situ hybridization for telomere length analysis to characterize the leukemic blasts of a three-year-old boy with KS and B-cell acute lymphoblastic leukemia (B-ALL), to gain insight into genomic evolution mechanisms in congenital aneuploidy and leukemic development. We found chromosomal instability and a significant reduction in telomere length in leukemic blasts when compared with the non-leukemic aneuploid cells. Reviewing published cases with KS and B-ALL revealed 20 additional cases with B-ALL diagnostic cytogenetics. Including our present case, 67.7% (14/21) had acquired two or more additional chromosomal aberrations at B-ALL diagnosis. The presented data indicate that congenital aneuploidy in B-ALL might be associated with chromosomal instability, which may be fueled by enhanced telomere attrition.

Telomeric zinc-finger associated protein (TZAP) in cancer biology: friend or foe?

The new identified protein telomeric zinc-finger associated protein (TZAP) is a negative regulator of telomere length. Since telomere length and telomere maintenance mechanisms are essential to cancer progression, TZAP is considered a new player in cancer biology. Here we aimed to analyze TZAP using the Cancer Genome Atlas data in a Pan-Cancer approach. We gathering data from TCGA Pan-Cancer studies utilizing cBioPortal, GEPIA and UALCAN. In total we analyzed 33 types of cancer (n=9664) and their respective controls (n=711). TZAP is transcribed in all cancers but less than 5% of all tumors show any somatic changes. TZAP was downregulated in kidney chromophobe carcinoma, and upregulated in esophageal cancer, head and neck squamous cell carcinomas, kidney renal clear cell carcinoma and in liver hepatocellular carcinoma. Globally, TZAP expression is related to favorable prognosis, associated to better overall and disease-free survival. Looking to specific tumors, TZAP expression has a dual behavior. Its downregulation is associated with poor prognosis in cervical squamous cell carcinoma, in kidney renal clear cell carcinoma, kidney papillary cell carcinoma, lung adenocarcinoma and pancreas adenocarcinoma. On the contrary, in adrenocortical carcinoma, colon and rectal cancer, brain lower grade glioma and prostate adenocarcinoma the upregulation of TZAP is related with poor prognosis. TZAP expression has a positive correlation with TRF1 and TRF2 in normal tissue but not in cancer. Our analyses indicate that TZAP has an important role in oncology and may be considered as a potential biomarker.

Dietary Pattern, Genomic Stability and Relative Cancer Risk in Asian Food Landscape

The incidence of cancer globally is increasing, partly due to lifestyle factors. Despite a better understanding of cancer biology and advancement in cancer management and therapies, current strategies in cancer treatment remain costly and cause socioeconomic burden especially in Asian countries. Hence, instead of putting more efforts in searches for new cancer cures, attention has now shifted to understanding how to mitigate cancer risk by modulating lifestyle factors. It has been established that carcinogenesis is multifactorial, and the important detrimental role of oxidative stress, chronic inflammation, and genomic instability is evident. To date, there is no study linking dietary pattern and genomic stability in cancer risk in the Asian food landscape. Thus, this present review article discusses recent literature on dietary pattern and genomic stability and its relationship with cancer risk in Asia.

Obesity and telomere status in the prognosis of patients with colorectal cancer submitted to curative intention surgical treatment

The risk of colorectal cancer (CRC) development has been associated with telomere dysfunction and obesity. However, clinical relevance of these parameters in CRC prognosis is not clear. Therefore, the aim of the present study was to evaluate the impact of obesity and telomere status in the prognosis of patients affected by CRC and submitted to curative surgical treatment. According to published data, this is the first work in which obesity and telomere status are jointly considered in relation to CRC prognosis. A prospective study including 162 patients with CRC submitted to curative surgical treatment was performed. Subjects were classified according to their BMI. Telomere status was established through telomere length and telomerase activity evaluation. Statistical analyses were performed using the SPSS software package version 22. Telomere shortening was inversely associated with BMI in patients with CRC. Notably, among patients with CRC, subjects with obesity exhibited less shortening of tumor telomeres than non-obese patients (P=0.047). Patients with shorter telomeres, both in the tumor (median telomere length <6.5 kb) and their non-tumor paired tissues (median telomere length <7.1 kb), had the best clinical evolution, regardless of the Dukes' stage of cancers (P=0.025, for tumor samples; P=0.003, for non-tumor samples). Additionally, subjects with a BMI >31.85 kg/m² showed the worse clinical outcomes compared with subjects with other BMI values. Interestingly, the impact of BMI showed sex dependence, since only the group of men displayed significant differences in CRC prognosis in relation to obesity status (P=0.037). From the results of the present study, based on a multivariate prediction model to establish prognosis, it was concluded that telomere length is a useful biomarker to predict prognosis in patients with CRC. Regardless of BMI values, the improved clinical evolution was associated with shorter telomeres. The impact of BMI seems to be associated with other factors, such as sex.

Telomere Shortening and Fusions: A Link to Aneuploidy in Early Human Embryo Development

Importance

It is known that oocytes undergo aging that is caused by exposure to an aged ovarian microenvironment. Telomere length in mouse and bovine oocytes declines with age, and age-associated telomere shortening in oocytes is considered a sign of poor development competency. Women with advanced age undergoing assisted reproductive technologies have poor outcomes because of increasing aneuploidy rates with age. Research has shown that aneuploidy is associated with DNA damage, reactive oxygen species, and telomere dysfunction.

Objective

In this review, we focus on the possible relationship between telomere dysfunction and aneuploidy in human early embryo development and several reproductive and perinatal outcomes, discussing the mechanism of aneuploidy caused by telomere shortening and fusion in human embryos.

Evidence Acquisition

We reviewed the current literature evidence concerning telomere dysfunction and aneuploidy in early human embryo development.

Results

Shorter telomeres in oocytes, leukocytes, and granulosa cells, related to aging in women, were associated with recurrent miscarriage, trisomy 21, ovarian insufficiency, and decreasing chance of in vitro fertilization success. Telomere length and telomerase activity in embryos have been related to the common genomic instability at the cleavage stage of human development. Complications of assisted reproductive technology pregnancies, such as miscarriage, birth defects, preterm births, and intrauterine growth restriction, also might result from telomere shortening as observed in oocytes, polar body, granulosa cells, and embryos.

Conclusions and Relevance

Telomere length clearly plays an important role in the development of the embryo and fetus, and the abnormal shortening of telomeres is likely involved in embryo loss during early human development. However, telomere fusion studies have yet to be performed in early human development.

Genetic predisposition to long telomeres is associated with increased mortality after melanoma: A study of 2101 melanoma patients from hospital clinics and the general population

Whether there is an association between measured and genetically predicted telomere length and melanoma mortality is unclear. We tested the hypothesis that measured and genetically predicted telomere length is associated with mortality after a melanoma diagnosis. We followed 2,101 patients with melanoma from hospital clinics and the general population for risk of death for up to 26 years. All had telomere length measured in DNA from leukocytes, and 2052 of these were genotyped for the three single nucleotide polymorphisms rs7726159 (TERT), rs1317082 (TERC), and rs2487999 (OBFC1); all three genotypes are associated with telomere length and combined into an allele count from 0 to 6. For each telomere-lengthening allele, the hazard ratios (HRs) for mortality in the age-adjusted and multivariable-adjusted Cox analysis were 1.12 (95% confidence interval: 1.02-1.23) and 1.11 (1.01-1.23). However, for each standard deviation increase in measured telomere length, HR for mortality was 0.97 (0.88-1.08). In conclusion, in more than 2000 melanoma patients from hospital clinics and from the general population, genetically predicted long telomeres were associated with increased mortality, but measured leukocyte telomere length was not.

Drug Repurposing of Itraconazole and Estradiol Benzoate against COVID-19 by Blocking SARS-CoV-2 Spike Protein-Mediated Membrane Fusion

SARS-CoV-2 caused the emerging epidemic of coronavirus disease in 2019 (COVID-19). To date, there are more than 82.9 million confirmed cases worldwide, there is no clinically effective drug against SARS-CoV-2 infection. The conserved properties of the membrane fusion domain of the spike (S) protein across SARS-CoV-2 make it a promising target to develop pan-CoV therapeutics. Herein, two clinically approved drugs, Itraconazole (ITZ) and Estradiol benzoate (EB), are found to inhibit viral entry by targeting the six-helix (6-HB) fusion core of SARS-CoV-2 S protein. Further studies shed light on the mechanism that ITZ and EB can interact with the heptad repeat 1 (HR1) region of the spike protein, to present anti-SARS-CoV-2 infections in vitro, indicating they are novel potential therapeutic remedies for COVID-19 treatment. Furthermore, ITZ shows broad-spectrum activity targeting 6-HB in the S2 subunit of SARS-CoV and MERS-CoV S protein, inspiring that ITZ have the potential for development as a pan-coronavirus fusion inhibitor.

MicroRNA-340-5p increases telomere length by targeting telomere protein POT1 to improve Alzheimer's disease in mice

Alzheimer's disease (AD) is a chronic neurodegenerative disorder which is the primary cause of dementia in the elderly. Telomere attrition has been proposed as a hallmark of aging. Our study aimed to explore the mechanism of the protection of telomere 1 (POT1) in regulating telomere length and affecting cellular senescence in AD. The AD mouse model was established by d-galactose and aluminum chloride, and the water maze test and dark avoidance test were used to detect the behaviors of mice and confirm the success of AD mouse model. AD cell model was established with HT22 cells induced by Aβ₄₂ oligomers. POT1 expression in the AD model was detected by quantitative real-time polymerase chain reaction. Cellular telomere length in hippocampal tissue was analyzed by telomere restriction fragment. Localization of intracellular POT1, telomerase, and telomeres was analyzed by immunofluorescence and fluorescence in situ hybridization. Dual-luciferase assay was used to validate the targeted binding relationship between microRNA-340-5p (miR-340-5p) and POT1. After inhibiting POT1 expression, the symptoms of AD in mice were improved. Aβ_1-42 deposition was reduced, whereas telomere length and telomerase activity was increased. Dual-luciferase assay verified the binding relationship between miR-340-5p and POT1. An increase in miR-340-5p expression could alleviate cellular senescence and AD symptoms. miR-340-5p increased cellular telomere length and delayed cell senescence by inhibiting POT1 expression to improve AD symptoms. This study made a conclusion that miR-340-5p increased cellular telomere length and delayed cell senescence by inhibiting POT1 expression to improve AD symptoms in mice.

Telomere shortening in head and neck cancer: association between DNA demethylation and survival

A growing body of evidence indicates that telomere dysfunction is a biological marker of progression in several types of cancer. However, the association between head and neck squamous cell carcinoma (HNSCC) and telomere length (TL) remains unknown. We measured the absolute TL levels in a well-characterised dataset of 211 tumoral vs normal tissues obtained from the same patients by quantitative polymerase chain reaction assay. Normalised TL levels were significantly lower in tumour samples than in normal tissue (P < 0.001) and there was a positive correlation between tumour tissue and normal mucosal tissue (R² = 0.176, P < 0.001). We were able to distinguish two classes, one with a tumour/normal TL ratio ≤ 0.3 (38.4%), which showed clear telomere erosion, and the other with a tumour/normal TL ratio > 0.3 (61.6%), in which the TL was slightly shorter or longer than that in normal tissue. Notably, the tumour/normal TL ratio was correlated with the likelihood of disease recurrence (P = 0.002), the 5-hydroxymethylcytosine level (P = 0.043), and expression of the ten-eleven translocation (TET) gene (P = 0.043). Our findings show that TL shortening and subsequent low levels of 5-hydroxymethylcytosine and TET expression may contribute to development of HNSCC.

Genetic Landscape of Papillary Thyroid Carcinoma and Nuclear Architecture: An Overview Comparing Pediatric and Adult Populations

Thyroid cancer is a rare malignancy in the pediatric population that is highly associated with disease aggressiveness and advanced disease stages when compared to adult population. The biological and molecular features underlying pediatric and adult thyroid cancer pathogenesis could be responsible for differences in the clinical presentation and prognosis. Despite this, the clinical assessment and treatments used in pediatric thyroid cancer are the same as those implemented for adults and specific personalized target treatments are not used in clinical practice. In this review, we focus on papillary thyroid carcinoma (PTC), which represents 80-90% of all differentiated thyroid carcinomas. PTC has a high rate of gene fusions and mutations, which can influence the histologic subtypes in both children and adults. This review also highlights telomere-related genomic instability and changes in nuclear organization as novel biomarkers for thyroid cancers.

Influence of cortisol awakening response on telomere length: Trends for males and females

Although telomere attrition is associated with the process of normal ageing, shorter telomere length (TL) has been associated with acute and chronic stressors. A neurobiological factor hypothesised to be responsible for this accelerated attrition is the dysregulation of the cortisol stress response, which can induce DNA damage affecting DNA telomeric caps. Marked sex differences are reported in both the cortisol stress response and telomere dynamics, yet no explicit investigation of sex specificity on the relationship between cortisol and TL exists. This study used mathematical equation modelling to describe the relationship between diurnal cortisol levels and telomere length within the context of sex, in a healthy population. Cortisol awakening responses (CAR) were measured via ELISA methodology in fifty-one healthy participants (28 males, 23 females). qPCRs determined TL from genomic DNA extracted from saliva. To assess the effect of free cortisol on relative TL ratio, a semi-log regression plot of the two variables trended for sex were fitted using spline curves. Results demonstrated significant differences between males and females in the relationship defining CAR and TL association (p = 0.03). These results suggest the relationship is not linear and can be represented as a complex arcsin function, and that the patterns are opposite in males and females. Males demonstrate a positive correlation, with higher levels of CAR being associated with longer telomere sequences. Females demonstrated a negative correlation. Future studies must carefully take into consideration moderating factors such as sex, and sex hormones across the lifespan when investigating telomere length.

The functional and structural connectomes of telomere length and their association with cognition in mild cognitive impairment

Previous findings on the relationship between telomere length and cognition have inconclusive, despite the relatively consistent telomere-shortening associated atrophy in the subcortical regions. Perhaps, there could be other more important telomere-associated factors in the brain, such as functional connectivity (FC) and structural connectivity (SC) that modulate cognition. The current study examined the relationship between telomere length, connectivity, and cognition. Telomere length measurements, neurocognitive scores, diffusion tensor and resting-state functional magnetic resonance imaging scans were collected from 82 older adults with mild cognitive impairment. SC and FC matrices were derived from these scans and, in various combinations, entered into connectome-based predictive models to predict telomere length. The telomere-associated features were then used to predict memory and executive functions. Leave-one-out cross-validation was performed. Predictive accuracy was assessed via the correlation between predicted and observed scores (r_{predicted-observed}). Correlation analyses were carried out between cognition and telomere length. Telomere length was significantly and negatively correlated with executive functions (EF), after controlling for demographical confounds. Telomere length was best predicted by negative SC and positive FC features (r_{predicted-observed} = .57; p < .001). The telomere-associated negative SC features significantly predicted EF scores (r_{predicted-observed} = -.26; p = .015). Telomere-shortening was associated with better EF and alterations in both FC and SC. This enhanced EF can be partly attributed to the telomere-associated changes in SC. Given that telomere is known to be a nonspecific marker of health, our findings illustrated a potential clinical use of telomere length to predict individualized health-related information from FC and SC features.

Molecular Pathogenesis of Hodgkin Lymphoma: Past, Present, Future

Our understanding of the tumorigenesis of classical Hodgkin lymphoma (cHL) and the formation of Reed–Sternberg cells (RS-cells) has evolved drastically in the last decades. More recently, a better characterization of the signaling pathways and the cellular interactions at play have paved the way for new targeted therapy in the hopes of improving outcomes. However, important gaps in knowledge remain that may hold the key for significant changes of paradigm in this lymphoma. Here, we discuss the past, present, and future of cHL, and review in detail the more recent discoveries pertaining to genetic instability, anti-apoptotic signaling pathways, the tumoral microenvironment, and host-immune system evasion in cHL.

Modulation of telomerase expression and function by miRNAs: Anti-cancer potential

Telomerase is a nucleoprotein reverse transcriptase that maintains the telomere, a protective structure at the ends of the chromosome, and is active in cancer cells, stem cells, and fetal cells. Telomerase immortalizes cancer cells and induces unlimited cell division by preventing telomere shortening. Immortalized cancer cells have unlimited proliferative potential due to telomerase activity that causes tumorigenesis and malignancy. Therefore, telomerase can be a lucrative anti-cancer target. The regulation of catalytic subunit of telomerase (TERT) determines the extent of telomerase activity. miRNAs, as an endogenous regulator of gene expression, can control telomerase activity by targeting TERT mRNA. miRNAs that have a decreasing effect on TERT translation mediate modulation of telomerase activity in cancer cells by binding to TERT mRNA and regulating TERT translation. In this review, we provide an update on miRNAs that influence telomerase activity by regulation of TERT translation.

Maternal stress or sleep during pregnancy are not reflected on telomere length of newborns

Telomeres play an important role in maintaining chromosomal integrity. With each cell division, telomeres are shortened and leukocyte telomere length (LTL) has therefore been considered a marker for biological age. LTL is associated with various lifetime stressors and health-related outcomes. Transgenerational effects have been implicated in newborns, with maternal stress, depression, and anxiety predicting shorter telomere length at birth, possibly reflecting the intrauterine growth environment. Previous studies, with relatively small sample sizes, have reported an effect of maternal stress, BMI, and depression during pregnancy on the LTL of newborns. Here, we attempted to replicate previous findings on prenatal stress and newborn LTL in a sample of 1405 infants using a qPCR-based method. In addition, previous research has been expanded by studying the relationship between maternal sleep quality and LTL. Maternal prenatal stress, anxiety, depression, BMI, and self-reported sleep quality were evaluated with self-reported questionnaires. Despite sufficient power to detect similar or even considerably smaller effects than those previously reported in the literature, we were unable to replicate the previous correlation between maternal stress, anxiety, depression, or sleep with LTL. We discuss several possible reasons for the discrepancies between our findings and those previously described.

Association of Relative Leucocyte Telomere Length and Gene Single Nucleotide Polymorphisms (TERT, TRF1, TNKS2) in Laryngeal Squamous Cell Carcinoma

BACKGROUND/AIM

The study aimed to evaluate associations of relative leukocyte telomere length (LTL) and polymorphisms of telomere length-associated genes TERT (rs2736098), TERT-CLPTM1L (rs401681), TRF1 (rs1545827, rs10107605) and TNKS2 (rs10509637, rs10509639) in patients with laryngeal squamous cell carcinoma (LSCC).

MATERIALS AND METHODS

The study consisted of 300 patients with LSCC and 369 healthy control subjects. Genotyping and relative LTL measuring were carried out using qPCR.

RESULTS

Relative LTL was statistically significantly shorter in the G3 (tumor differentiation grade) subgroup of patients with LSCC compared to the G1 and G2 subgroups. Significant differences were found in genotype distributions of TERT rs401681 and TNKS2 rs10509639 between the study groups. TERT rs401681 C/T and T/T genotypes were associated with approximately 30% decreased odds of LSCC development.

CONCLUSION

LTL was shorter in the G3 subgroup compared to the G2 and G1 subgroups of LSCC patients. TERT rs401681 and its C/T and T/T genotypes were associated with decreased odds of overall LSCC development.

Repair and Reconstruction of Telomeric and Subtelomeric Regions and Genesis of New Telomeres: Implications for Chromosome Evolution

DNA damage repair within telomeres are suppressed to maintain the integrity of linear chromosomes, but the accidental activation of repairs can lead to genome instability. This review develops the concept that mechanisms to repair DNA damage in telomeres contribute to genetic variability and karyotype evolution, rather than catastrophe. Spontaneous breaks in telomeres can be repaired by telomerase, but in some cases DNA repair pathways are activated, and can cause chromosomal rearrangements or fusions. The resultant changes can also affect subtelomeric regions that are adjacent to telomeres. Subtelomeres are actively involved in such chromosomal changes, and are therefore the most variable regions in the genome. The case of Caenorhabditis elegans in the context of changes of subtelomeric structures revealed by long-read sequencing is also discussed. Theoretical and methodological issues covered in this review will help to explore the mechanism of chromosome evolution by reconstruction of chromosomal ends in nature.

The enigma of excessively long telomeres in cancer: lessons learned from rare human POT1 variants

The discovery that rare POT1 variants are associated with extremely long telomeres and increased cancer predisposition has provided a framework to revisit the relationship between telomere length and cancer development. Telomere shortening is linked with increased risk for cancer. However, over the past decade, there is increasing evidence to show that extremely long telomeres caused by mutations in shelterin components (POT1, TPP1, and RAP1) also display an increased risk of cancer. Here, we will review current knowledge on germline mutations of POT1 identified from cancer-prone families. In particular, we will discuss some common features presented by the mutations through structure-function studies. We will further provide an overview of how POT1 mutations affect telomere length regulation and tumorigenesis.

Genome rearrangements associated with aberrant telomere maintenance

There is unequivocal evidence that telomeres are crucial for cellular homeostasis and that telomere dysfunction can elicit genome instability and potentially initiate events that culminate in cancer. Mounting evidence points to telomeres having a crucial role in driving local and systemic structural rearrangements that drive cancer. These include the classical 'breakage-fusion-bridge' (BFB) cycles and more recently identified genome re-shaping events like kataegis and chromothripsis. In this brief review, we outline the established and most recent advances describing the roles that telomere dysfunction has in the origin of these catastrophic genome rearrangements. We discuss how local and systemic structural rearrangements enable telomere length maintenance, by either telomerase or the alternative lengthening of telomeres, that is essential to sustain cancer cell proliferation.

Tumor Suppressor LKB1 inhibits both the mRNA Expression and the Amplification of hTERC by the Phosphorylation of YAP in Lung Cancer Cells

Liver kinase B1 (LKB1) is a critical tumor suppressor that is frequently mutated in human cancers. LKB1 has serine/threonine protein kinase activity, which regulates gene expression by phosphorylation of Yes-Associated protein (YAP). The phosphorylation-dependent YAP shuttling is critically important intracellular mechanism in the Hippo pathway. In our previous study, we found that the amplification of hTERC was significant higher in the bronchial brushing cells of patients with lung cancer, however, the underlying molecular mechanism is not clear. In this study, we showed that LKB1 overexpression could phosphorylate YAP and promoted its nuclear rejection. Silencing LKB1 could dephosphorylate YAP and promoted its entry into the nucleus. Here, we found that LKB1 inhibited the mRNA expression and the amplification of hTERC. YAP further up-regulated hTERC at mRNA and gene amplification levels. Therefore, we suggest that LKB1 may inhibit the expression and amplification of hTERC through the axis of LKB1-pYAP(YAP)-hTERC.

Stem cells, immortality, and the evolution of metastatic properties in breast cancer: telomere maintenance mechanisms and metastatic evolution

Breast cancer is the most significant cause of cancer-related death in women around the world. The vast majority of breast cancer-associated mortality stems from metastasis, which remains an incurable disease state. Metastasis results from evolution of clones that possess the insidious properties required for dissemination and colonization of distant organs. These clonal populations are descended from breast cancer stem cells (CSCs), which are also responsible for their prolonged maintenance and continued evolution. Telomeres impose a lifespan on cells that can be extended when they are actively elongated, as occurs in CSCs. Thus, changes in telomere structure serve to promote the survival of CSCs and subsequent metastatic evolution. The selection of telomere maintenance mechanism (TMM) has important consequences not only for CSC survival and evolution, but also for their coordination of various signaling pathways that choreograph the metastatic cascade. Targeting the telomere maintenance machinery may therefore provide a boon to the treatment of metastatic breast cancer. Here we review the two major TMMs and the roles they play in the development of stem and metastatic breast cancer cells. We also highlight current and future approaches to targeting these mechanisms in clinical settings to alleviate metastatic breast cancers.

Chromothripsis during telomere crisis is independent of NHEJ, and consistent with a replicative origin

Telomere erosion, dysfunction, and fusion can lead to a state of cellular crisis characterized by large-scale genome instability. We investigated the impact of a telomere-driven crisis on the structural integrity of the genome by undertaking whole-genome sequence analyses of clonal populations of cells that had escaped crisis. Quantification of large-scale structural variants revealed patterns of rearrangement consistent with chromothripsis but formed in the absence of functional nonhomologous end-joining pathways. Rearrangements frequently consisted of short fragments with complex mutational patterns, with a repair topology that deviated from randomness showing preferential repair to local regions or exchange between specific loci. We find evidence of telomere involvement with an enrichment of fold-back inversions demarcating clusters of rearrangements. Our data suggest that chromothriptic rearrangements caused by a telomere crisis arise via a replicative repair process involving template switching.

Modelling chromosome structural and copy number changes to understand cancer genomes

Cancer cells differ from healthy cells by genetic information that is massively altered not only by point mutations and small insertions and deletions, but also by large scale changes such as chromosomal rearrangements as well as gains and losses of individual chromosomes or entire chromosome sets. How exactly large-scale chromosomal abnormalities contribute to tumorigenesis has been difficult to study. Remarkable progress has been recently made thanks to in vitro models that mimic large-scale chromosomal aberrations and allow their systematic analysis. The obtained findings reveal that genomic alterations strongly affect the cellular physiology and, importantly, instigate further genomic instability. This suggests that these model systems might provide novel insights by recapitulating the processes that occur during tumorigenesis.

Heterogeneous Nuclear Ribonucleoproteins Involved in the Functioning of Telomeres in Malignant Cells

Heterogeneous nuclear ribonucleoproteins (hnRNPs) are structurally and functionally distinct proteins containing specific domains and motifs that enable the proteins to bind certain nucleotide sequences, particularly those found in human telomeres. In human malignant cells (HMCs), hnRNP-A1-the most studied hnRNP-is an abundant multifunctional protein that interacts with telomeric DNA and affects telomerase function. In addition, it is believed that other hnRNPs in HMCs may also be involved in the maintenance of telomere length. Accordingly, these proteins are considered possible participants in the processes associated with HMC immortalization. In our review, we discuss the results of studies on different hnRNPs that may be crucial to solving molecular oncological problems and relevant to further investigations of these proteins in HMCs.

The three-dimensional cancer nucleus

Research into the three-dimensional (3D) organization of the cancer cell genome started over 100 years ago. We follow an exciting avenue of research in this field, from Hansemann's early observations of aberrant mitoses and nuclei in cancer cells in the late 19th century to Boveri's theory of the cancer cell in the early 20th century, to current views of nuclear organization and its changes in cancer. Molecular and imaging methods go hand in hand with providing us with a better understanding of the spatial nature of the cancer cell genome. This has led to the concept that the structural order of the nucleus can be used as cancer cell biomarker.

Intriguing Relationships Between Cancer and Systemic Sclerosis: Role of the Immune System and Other Contributors

Systemic sclerosis (SSc) is an autoimmune connective tissue disorder, characterized by multisystem involvement, vasculopathy, and fibrosis. An increased risk of malignancy is observed in SSc (including breast and lung cancers), and in a subgroup of patients with specific autoantibodies (i.e., anti-RNA polymerase III and related autoantibodies), SSc could be a paraneoplastic syndrome and might be directly related to an immune response against cancer. Herein, we reviewed the literature, focusing on the most recent articles, and shed light onto the potential relationship between cancer and scleroderma regarding temporal and immunological dimensions.

Exercise, Telomeres, and Cancer: "The Exercise-Telomere Hypothesis"

Telomeres are genomic complex at the end of chromosomes that protects the DNA and telomere length (TL) is related to several age-related diseases, lifespan, and cancer. On the other hand, cancer is a multifactorial disease that is responsible for reduce the quality of life and kills millions of people every year. Both, shorter TL and cancer are related and could be treated or prevented depending of the lifestyle. In this review we discuss the possible role of exercise in the relationship between shorter telomeres, telomerase activity, and cancer. In summary, there is evidence that exercise leads to less telomere attrition and exercise also may diminish the risk of cancer, these two outcomes are possible intermediated by a reduction in oxidative stress, and chronic inflammation. Although, there is evidence that shorter TL are associated with cancer, the possible mechanisms that one may lead to the other remains to be clarified. We assume that humans under cancer treatment may suffer a great decrease in quality of life, which may increase sedentary behavior and lead to increased telomere attrition. And those humans with already shorter TL likely lived under a poor lifestyle and might have an increased risk to have cancer.