Telomerase in Cancer: Function, Regulation, and Clinical Translation

LASSO regression and WGCNA-based telomerase-associated lncRNA signaling predicts clear cell renal cell carcinoma prognosis and immunotherapy response

OBJECTIVE

To investigate whether telomerase-associated lncRNA expression affects the prognosis and anti-tumor immunity of patients with renal clear cell carcinoma (ccRCC).

METHODS

A series of analyses were performed to establish a prognostic risk model and validate its accuracy. Immune-related analyses were performed to assess further the association between immune status, tumor microenvironment, and prognostic risk models.

RESULTS

Eight telomerase-associated lncRNAs associated with prognosis were identified and applied to establish a prognostic risk model. Overall survival was higher in the low-risk group.

CONCLUSION

The established prognostic risk model has a good predictive ability for the prognosis of ccRCC patients and provides a new possible therapeutic target for ccRCC.

Arabidopsis AN3 and OLIGOCELLULA genes link telomere maintenance mechanisms with cell division and expansion control

Telomeres are conserved chromosomal structures necessary for continued cell division and proliferation. In addition to the classical telomerase pathway, multiple other genes including those involved in ribosome metabolism and chromatin modification contribute to telomere length maintenance. We previously reported that Arabidopsis thaliana ribosome biogenesis genes OLI2/NOP2A, OLI5/RPL5A and OLI7/RPL5B have critical roles in telomere length regulation. These three OLIGOCELLULA genes were also shown to function in cell proliferation and expansion control and to genetically interact with the transcriptional co-activator ANGUSTIFOLIA3 (AN3). Here we show that AN3-deficient plants progressively lose telomeric DNA in early homozygous mutant generations, but ultimately establish a new shorter telomere length setpoint by the fifth mutant generation with a telomere length similar to oli2/nop2a -deficient plants. Analysis of double an3 oli2 mutants indicates that the two genes are epistatic for telomere length control. Telomere shortening in an3 and oli mutants is not caused by telomerase inhibition; wild type levels of telomerase activity are detected in all analyzed mutants in vitro. Late generations of an3 and oli mutants are prone to stem cell damage in the root apical meristem, implying that genes regulating telomere length may have conserved functional roles in stem cell maintenance mechanisms. Multiple instances of anaphase fusions in late generations of oli5 and oli7 mutants were observed, highlighting an unexpected effect of ribosome biogenesis factors on chromosome integrity. Overall, our data implicate AN3 transcription coactivator and OLIGOCELLULA proteins in the establishment of telomere length set point in plants and further suggest that multiple regulators with pleiotropic functions can connect telomere biology with cell proliferation and cell expansion pathways.

All-trans-retinoic acid modulates glycolysis via H19 and telomerase: the role of mir-let-7a in estrogen receptor-positive breast cancer cells

BACKGROUND

Breast cancer (BC) is the most commonly diagnosed cancer in women. Treatment approaches that differ between estrogen-positive (ER+) and triple-negative BC cells (TNBCs) and may subsequently affect cancer biomarkers, such as H19 and telomerase, are an emanating delight in BC research. For instance, all-trans-Retinoic acid (ATRA) could represent a potent regulator of these oncogenes, regulating microRNAs, mostly let-7a microRNA (miR-let-7a), which targets the glycolysis pathway, mainly pyruvate kinase M2 (PKM2) and lactate dehydrogenase A (LDHA) enzymes. Here, we investigated the potential role of ATRA in H19, telomerase, miR-let-7a, and glycolytic enzymes modulation in ER + and TNBC cells.

METHODS

MCF-7 and MDA-MB-231 cells were treated with 5 µM ATRA and/or 100 nM fulvestrant. Then, ATRA-treated or control MCF-7 cells were transfected with either H19 or hTERT siRNA. Afterward, ATRA-treated or untreated MDA-MB-231 cells were transfected with estrogen receptor alpha ER(α) or beta ER(β) expression plasmids. RNA expression was evaluated by RT‒qPCR, and proteins were assessed by Western blot. PKM2 activity was measured using an NADH/LDH coupled enzymatic assay, and telomerase activity was evaluated with a quantitative telomeric repeat amplification protocol assay. Student's t-test or one-way ANOVA was used to analyze data from replicates.

RESULTS

Our results showed that MCF-7 cells were more responsive to ATRA than MDA-MB-231 cells. In MCF-7 cells, ATRA and/or fulvestrant decreased ER(α), H19, telomerase, PKM2, and LDHA, whereas ER(β) and miR-let-7a increased. H19 or hTERT knockdown with or without ATRA treatment showed similar results to those obtained after ATRA treatment, and a potential interconnection between H19 and hTERT was found. However, in MDA-MB-231 cells, RNA expression of the aforementioned genes was modulated after ATRA and/or fulvestrant, with no significant effect on protein and activity levels. Overexpression of ER(α) or ER(β) in MDA-MB-231 cells induced telomerase activity, PKM2 and LDHA expression, in which ATRA treatment combined with plasmid transfection decreased glycolytic enzyme expression.

CONCLUSIONS

To the best of our knowledge, our study is the first to elucidate a new potential interaction between the estrogen receptor and glycolytic enzymes in ER + BC cells through miR-let-7a.

Exploring active ingredients and mechanisms of Coptidis Rhizoma-ginger against colon cancer using network pharmacology and molecular docking

BACKGROUND

Colon cancer is the most prevalent and rapidly increasing malignancy globally. It has been suggested that some of the ingredients in the herb pair of Coptidis Rhizoma and ginger (Zingiber officinale), a traditional Chinese medicine, have potential anti-colon cancer properties.

OBJECTIVE

This study aimed to investigate the molecular mechanisms underlying the effects of the Coptidis Rhizoma-ginger herb pair in treating colon cancer, using an integrated approach combining network pharmacology and molecular docking.

METHODS

The ingredients of the herb pair Coptidis Rhizoma-ginger, along with their corresponding protein targets, were obtained from the Traditional Chinese Medicine System Pharmacology and Swiss Target Prediction databases. Target genes associated with colon cancer were retrieved from the GeneCards and OMIM databases. Then, the protein targets of the active ingredients in the herb pair were identified, and the disease-related overlapping targets were determined using the Venn online tool. The protein-protein interaction (PPI) network was constructed using STRING database and analyzed using Cytoscape 3.9.1 to identify key targets. Then, a compound-target-disease-pathway network map was constructed. The intersecting target genes were subjected to Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses for colon cancer treatment. Molecular docking was performed using the Molecular Operating Environment (MOE) software to predict the binding affinity between the key targets and active compounds.

RESULTS

Besides 1922 disease-related targets, 630 targets associated with 20 potential active compounds of the herb pair Coptidis Rhizoma-ginger were collected. Of these, 229 intersection targets were obtained. Forty key targets, including STAT3, Akt1, SRC, and HSP90AA1, were further analyzed using the ClueGO plugin in Cytoscape. These targets are involved in biological processes such as miRNA-mediated gene silencing, phosphatidylinositol 3-kinase (PI3K) signaling, and telomerase activity. KEGG enrichment analysis showed that PI3K-Akt and hypoxia-inducible factor 1 (HIF-1) signaling pathways were closely related to colon cancer prevention by the herb pair Coptidis Rhizoma-ginger. Ten genes (Akt1, TP53, STAT3, SRC, HSP90AA1, JAK2, CASP3, PTGS2, BCl2, and ESR1) were identified as key genes for validation through molecular docking simulation.

CONCLUSIONS

This study demonstrated that the herb pair Coptidis Rhizoma-ginger exerted preventive effects against colon cancer by targeting multiple genes, utilizing various active compounds, and modulating multiple pathways. These findings might provide the basis for further investigations into the molecular mechanisms underlying the therapeutic effects of Coptidis Rhizoma-ginger in colon cancer treatment, potentially leading to the development of novel drugs for combating this disease.

A Review of the Repair of DNA Double Strand Breaks in the Development of Oral Cancer

We explore the possibility that defects in genes associated with the response and repair of DNA double strand breaks predispose oral potentially malignant disorders (OPMD) to undergo malignant transformation to oral squamous cell carcinoma (OSCC). Defects in the homologous recombination/Fanconi anemia (HR/FA), but not in the non-homologous end joining, causes the DNA repair pathway to appear to be consistent with features of familial conditions that are predisposed to OSCC (FA, Bloom's syndrome, Ataxia Telangiectasia); this is true for OSCC that occurs in young patients, sometimes with little/no exposure to classical risk factors. Even in Dyskeratosis Congenita, a disorder of the telomerase complex that is also predisposed to OSCC, attempts at maintaining telomere length involve a pathway with shared HR genes. Defects in the HR/FA pathway therefore appear to be pivotal in conditions that are predisposed to OSCC. There is also some evidence that abnormalities in the HR/FA pathway are associated with malignant transformation of sporadic cases OPMD and OSCC. We provide data showing overexpression of HR/FA genes in a cell-cycle-dependent manner in a series of OPMD-derived immortal keratinocyte cell lines compared to their mortal counterparts. The observations in this study argue strongly for an important role of the HA/FA DNA repair pathway in the development of OSCC.

Effects of metformin and silodosin as supplementary treatments to abiraterone on human telomerase reverse transcriptase (hTERT) level in metastatic castration-resistant prostate cancer (mCRPC) cells: An in vitro study

The antiproliferative properties of metformin and silodosin have been observed in prostate cancer. Furthermore, it is hypothesized that the molecular pathways related to these drugs may impact the levels of human telomerase reverse transcriptase (hTERT) in prostate cancer cells. The aim of this study was to assess the effect of metformin and silodosin on the levels of hTERT in metastatic castration-resistant prostate cancer (mCRPC) cells. The present study employed an experimental design with a post-test-only control group. This study utilized the PC3 cell line as a model for mCRPC. A viability experiment was conducted using the CCK-8 method to determine the inhibitory concentration (IC50) values of metformin, silodosin, and abiraterone acetate (AA) after a 72-hour incubation period of PC3 cells. In order to investigate the levels of hTERT, PC3 cells were divided into two control groups: a negative control and a standard therapy with AA. Additionally, three experimental combination groups were added: metformin with AA; silodosin with AA; and metformin, silodosin and AA. The level of hTERT was measured using sandwich ELISA technique. The difference in hTERT levels was assessed using ANOVA followed by a post hoc test. The IC50 values for metformin, silodosin, and AA were 17.7 mM, 44.162 mM, and 66.9 μM, respectively. Our data indicated that the combination of metformin with AA and the combination of metformin, silodosin and AA decreased the hTERT levels when compared to control, AA, and silodosin with AA. The administration of metformin resulted in a reduction of hTERT levels in the PC3 cell line, but the impact of silodosin on hTERT levels was not statistically significant compared to AA group.

Telomerase inhibitors induce mitochondrial oxidation and DNA damage-dependent cell death rescued by Bcl-2/Bcl-xL

BACKGROUND

Reactivation of telomerase is a hallmark of cancer and the majority of cancers over-express telomerase. Telomerase-dependent telomere length maintenance confers immortality to cancer cells. However, telomere length-independent cell survival functions of telomerase also play a critical role in tumorigenesis. Multiple telomerase inhibitors have been developed as therapeutics and include anti-sense oligonucleotides, telomerase RNA component targeting agents, chemical inhibitors of telomerase, small molecule inhibitors of hTERT, and telomerase vaccine. In general, telomerase inhibitors affect cell proliferation and survival of cells depending on the telomere length reduction, culminating in replicative senescence or cell death by crisis. However, most telomerase inhibitors kill cancer cells prior to significant reduction in telomere length, suggesting telomere length independent role of telomerase in early telomere dysfunction-dependent cell death.

METHODS

In this study, we explored the mechanism of cell death induced by three prominent telomerase inhibitors utilizing a series of genetically encoded sensor cells including redox and DNA damage sensor cells.

RESULTS

We report that telomerase inhibitors induce early cell cycle inhibition, followed by redox alterations at cytosol and mitochondria. Massive mitochondrial oxidation and DNA damage induce classical cell death involving mitochondrial transmembrane potential loss and mitochondrial permeabilization. Real-time imaging of the progression of mitochondrial oxidation revealed that treated cells undergo a biphasic mitochondrial redox alteration during telomerase inhibition, emphasizing the potential role of telomerase in the redox regulation at mitochondria. Additionally, silencing of hTERT confirmed its predominant role in maintaining mitochondrial redox homeostasis. Interestingly, the study also demonstrated that anti-apoptotic Bcl-2 family proteins still confer protection against cell death induced by telomerase inhibitors.

CONCLUSION

The study demonstrates that redox alterations and DNA damage contribute to early cell death by telomerase inhibitors and anti-apoptotic Bcl-2 family proteins confer protection from cell death by their ability to safeguard mitochondria from oxidation damage.

Immunolocalization of telomerases in human hairs identifies proliferating cells in the bulb matrix and outer root sheath

Telomerase is present in cells with numerous or even un-limited replicative cycles, and some studies suggest it is a stemness marker. In order to determine whether this is the case for the human hair bulbs, an immunohistochemical and ultrastructural study has been carried out using antibodies against telomerase and PCNA (a cell proliferation marker). The observed labeling is similar for the two antibodies here utilized and is mainly nuclear. More frequent telomerase-positive cells are seen in the matrix epithelium of anagen hair bulbs but sparse labeled cells are also seen in the outer root sheath. In late catagen and also in telogen hair follicles only sparse labeled cells are present in the outer root sheath and few cells also in the secondary germinal epithelium formed at the base of the hair bulb in telogen. Electron microscopic immunogold shows a prevalent nuclear distribution and a lower cytoplasmic distribution in sparse cells of anagen bulb matrix that contain few keratin bundles. The nuclear localization is generally seen over the euchromatin or in areas occupied by more compact chromatin that may indicate an activity of telomerase in chromatin assemblage or dis-assemblage. The study concludes that the localization of telomerase is present in cells undergoing proliferation, namely transit amplifying cells of the outer root sheath that are sparsely detected in the lowermost secondary germinal hair bulb also in telogen.

Exploring the Prospective Role of Propolis in Modifying Aging Hallmarks

Aging populations worldwide are placing age-related diseases at the forefront of the research agenda. The therapeutic potential of natural substances, especially propolis and its components, has led to these products being promising agents for alleviating several cellular and molecular-level changes associated with age-related diseases. With this in mind, scientists have introduced a contextual framework to guide future aging research, called the hallmarks of aging. This framework encompasses various mechanisms including genomic instability, epigenetic changes, mitochondrial dysfunction, inflammation, impaired nutrient sensing, and altered intercellular communication. Propolis, with its rich array of bioactive compounds, functions as a potent functional food, modulating metabolism, gut microbiota, inflammation, and immune response, offering significant health benefits. Studies emphasize propolis' properties, such as antitumor, cardioprotective, and neuroprotective effects, as well as its ability to mitigate inflammation, oxidative stress, DNA damage, and pathogenic gut bacteria growth. This article underscores current scientific evidence supporting propolis' role in controlling molecular and cellular characteristics linked to aging and its hallmarks, hypothesizing its potential in geroscience research. The aim is to discover novel therapeutic strategies to improve health and quality of life in older individuals, addressing existing deficits and perspectives in this research area.

Ellagic Acid and Cancer Hallmarks: Insights from Experimental Evidence

Cancer is a complex and multifaceted disease with a high global incidence and mortality rate. Although cancer therapy has evolved significantly over the years, numerous challenges persist on the path to effectively combating this multifaceted disease. Natural compounds derived from plants, fungi, or marine organisms have garnered considerable attention as potential therapeutic agents in the field of cancer research. Ellagic acid (EA), a natural polyphenolic compound found in various fruits and nuts, has emerged as a potential cancer prevention and treatment agent. This review summarizes the experimental evidence supporting the role of EA in targeting key hallmarks of cancer, including proliferation, angiogenesis, apoptosis evasion, immune evasion, inflammation, genomic instability, and more. We discuss the molecular mechanisms by which EA modulates signaling pathways and molecular targets involved in these cancer hallmarks, based on in vitro and in vivo studies. The multifaceted actions of EA make it a promising candidate for cancer prevention and therapy. Understanding its impact on cancer biology can pave the way for developing novel strategies to combat this complex disease.

Involvement of Inheritance in Determining Telomere Length beyond Environmental and Lifestyle Factors

All linear chromosomal ends have specific DNA-protein complexes called telomeres. Telomeres serve as a "molecular clock" to estimate the potential length of cell replication. Shortening of telomere length (TL) is associated with cellular senescence, aging, and various age-related diseases in humans. Here we reviewed the structure, function, and regulation of telomeres and the age-related diseases associated with telomere attrition. Among the various determinants of TL, we highlight the connection between TL and heredity to provide a new overview of genetic determinants for TL. Studies across multiple species have shown that maternal and paternal TL influence the TL of their offspring, and this may affect life span and their susceptibility to age-related diseases. Hence, we reviewed the linkage between TL and parental influences and the proposed mechanisms involved. More in-depth studies on the genetic mechanism for TL attrition are needed due to the potential application of this knowledge in human medicine to prevent premature frailty at its earliest stage, as well as promote health and longevity.

Arabidopsis AN3 and OLIGOCELLULA genes link telomere maintenance mechanisms with cell division and expansion control

Telomeres are conserved chromosomal structures necessary for continued cell division and proliferation. In addition to the classical telomerase pathway, multiple other genes including those involved in ribosome metabolism and chromatin modification contribute to telomere length maintenance. We previously reported that Arabidopsis thaliana ribosome biogenesis genes OLI2/NOP2A, OLI5/RPL5A and OLI7/RPL5B have critical roles in telomere length regulation. These three OLIGOCELLULA genes were also shown to function in cell proliferation and expansion control and to genetically interact with the transcriptional co-activator ANGUSTIFOLIA3 (AN3). Here we show that AN3-deficient plants progressively lose telomeric DNA in early homozygous mutant generations, but ultimately establish a new shorter telomere length setpoint by the fifth mutant generation with a telomere length similar to oli2/nop2a - deficient plants. Analysis of double an3 oli2 mutants indicates that the two genes are epistatic for telomere length control. Telomere shortening in an3 and oli mutants is not caused by telomerase inhibition; wild type levels of telomerase activity are detected in all analyzed mutants in vitro. Late generations of an3 and oli mutants are prone to stem cell damage in the root apical meristem, implying that genes regulating telomere length may have conserved functional roles in stem cell maintenance mechanisms. Multiple instances of anaphase fusions in late generations of oli5 and oli7 mutants were observed, highlighting an unexpected effect of ribosome biogenesis factors on chromosome integrity. Overall, our data implicate AN3 transcription coactivator and OLIGOCELLULA proteins in the establishment of telomere length set point in plants and further suggest that multiple regulators with pleiotropic functions can connect telomere biology with cell proliferation and cell expansion pathways.

Association of TERT (rs2736098 and rs2736100) genetic variants with elevated risk of hepatocellular carcinoma: a retrospective case-control study

Hepatocellular carcinoma (HCC) is an inflammatory problematic issue with higher mortality among different ethnic populations. The telomerase reverse transcriptase (TERT) gene has an imperative role in the proliferation of various cancerous illnesses, particularly HCC. Moreover, the TERT (rs2736098 and rs2739100) variants were correlated with the HCC susceptibility and telomere shortening, but with unconvincing outcomes. The main purpose of this outward work is to assess the correlation between these significant variants within the TERT gene and the elevated risk of HCC with the aid of various computational bioinformatics tools. This study included 233 participants [125 cancer-free controls and 108 HCC patients] from the same locality. In addition, 81.5% of HCC patients were positive for HCV autoantibodies, while 73.1% of HCC patients were positive for cirrhotic liver. Genomic DNA of the TERT (rs2736098 and rs2736100) variants were characterized utilizing the PCR-RFLP method. Interestingly, the frequencies of TERT (rs2736098*A allele) and TERT (rs2736100*T allele) conferred a significant correlation with increased risk of HCC compared to healthy controls (p-value = 0.002, and 0.016, respectively). The TERT (rs2736098*A/A) genotype indicated a definite association with positive smoking and splenomegaly (p-value < 0.05), while the TERT (rs2736100*T/T) genotype observed a significant difference with higher levels of HCV autoantibodies (p-value = 0.009). In conclusion, this significant work confirmed the contribution of the TERT (rs2736098*A and rs2736100*T) alleles with elevated risk of HCC progression and telomere shortening among Egyptian subjects.

Senescence in cancer: Advances in detection and treatment modalities

Senescence is a form of irreversible cell cycle arrest. Senescence plays a dual role in cancer, as both a tumor suppressor by preventing the growth of damaged cells and a cancer promoter by creating an inflammatory milieu. Stress-induced premature senescence (SIPS) and replicative senescence are the two major sub-types of senescence. Senescence plays a dual role in cancer, depending on the context and kind of senescence involved. SIPS can cause cancer by nurturing an inflammatory environment, whereas replicative senescence may prevent cancer. Major pathways that are involved in senescence are the p53-p21, p16INK4A-Rb pathway along with mTOR, MAPK, and PI3K pathways. The lack of universal senescence markers makes it difficult to identify senescent cells in vivo. A combination of reliable detection methods of senescent cells in vivo is of utmost importance and will help in early detection and open new avenues for future treatment. New strategies that are being developed in order to tackle these shortcomings are in the field of fluorescent probes, nanoparticles, positron emission tomography probes, biosensors, and the detection of cell-free DNA from liquid biopsies. Along with detection, eradication of these senescent cells is also important to prevent cancer reoccurrence. Recently, the field of nano-senolytic and immunotherapy has also been emerging. This review provides up-to-date information on the various types of advancements made in the field of detection and treatment modalities for senescent cells that hold promise for the future treatment and prognosis of cancer, as well as their limitations and potential solutions.

Nuclear and Cytoplasmic hTERT, Tumor-Infiltrating Lymphocytes, and Telomere Elongation Leukocytes Are Independent Factors in the Response to Neoadjuvant Treatment in HER2-Enriched Breast Cancer

HER2-enriched tumors are responsible for 20% of breast tumors and have high rates of immune infiltrates in the tumor stroma that respond favorably to neoadjuvant chemotherapy. In the context of tumors, telomeres control cell death and prevent tumor cells from replicating discontinuously, leading to their immortalization. This study aimed to evaluate the presence of tumor-infiltrating lymphocytes, hTERT expression, hTERT promoter mutation, and leukocyte telomere length in HER2-enriched breast tumors. A total of 103 cases were evaluated, 19 with pathologic complete response. The TILs percentage was above ≥10 in 44 cases (43%) and significantly present in patients ≥50 years of age. hTERT staining positivity was mostly nuclear, significantly present in the non-pCR group, and associated with a lower survival rate. Leukocyte telomeres were elongated for HER2-enriched tumors, and in multivariate analysis, shortening was associated with an increased risk of death. Overall, our results show that the nuclear and cytoplasmic presence of hTERT may indicate a worse prognosis and that leukocyte telomere elongation is a protective factor.

Alpha-ketoglutarate as a potent regulator for lifespan and healthspan: Evidences and perspectives

Aging is a natural process that determined by a functional decline in cells and tissues as organisms are growing old, resulting in an increase at risk of disease and death. To this end, many efforts have been made to control aging and increase lifespan and healthspan. These efforts have led to the discovery of several anti-aging drugs and compounds such as rapamycin and metformin. Recently, alpha-ketoglutarate (AKG) has been introduced as a potential anti-aging metabolite that can control several functions in organisms, thereby increases longevity and improves healthspan. Unlike other synthetic anti-aging drugs, AKG is one of the metabolites of the tricarboxylic acid (TCA) cycle, also known as the Krebs cycle, and synthesized in the body. It plays a crucial role in the cell energy metabolism, amino acid/protein synthesis, epigenetic regulation, stemness and differentiation, fertility and reproductive health, and cancer cell behaviors. AKG exerts its effects through different mechanisms such as inhibiting mTOR and ATP-synthase, modulating DNA and histone demethylation and reducing ROS formation. Herein, we summarize the recent findings of AKG-related lifespan and healthspan studies and discuss AKG associated cell and molecular mechanisms involved in increasing longevity, improving reproduction, and modulating stem cells and cancer cells behavior. We also discuss the promises and limitations of AKG for delaying aging and other potential applications.

Telomere Length Changes in Cancer: Insights on Carcinogenesis and Potential for Non-Invasive Diagnostic Strategies

Telomere dynamics play a crucial role in the maintenance of chromosome integrity; changes in telomere length may thus contribute to the development of various diseases including cancer. Understanding the role of telomeric DNA in carcinogenesis and detecting the presence of cell-free telomeric DNA (cf-telDNA) in body fluids offer a potential biomarker for novel cancer screening and diagnostic strategies. Liquid biopsy is becoming increasingly popular due to its undeniable benefits over conventional invasive methods. However, the organization and function of cf-telDNA in the extracellular milieu are understudied. This paper provides a review based on 3,398,017 cancer patients, patients with other conditions, and control individuals with the aim to shed more light on the inconsistent nature of telomere lengthening/shortening in oncological contexts. To gain a better understanding of biological factors (e.g., telomerase activation, alternative lengthening of telomeres) affecting telomere homeostasis across different types of cancer, we summarize mechanisms responsible for telomere length maintenance. In conclusion, we compare tissue- and liquid biopsy-based approaches in cancer assessment and provide a brief outlook on the methodology used for telomere length evaluation, highlighting the advances of state-of-the-art approaches in the field.

The Relevance of Telomerase and Telomere-Associated Proteins in B-Acute Lymphoblastic Leukemia

Telomeres and telomerase are closely linked to uncontrolled cellular proliferation, immortalization and carcinogenesis. Telomerase has been largely studied in the context of cancer, including leukemias. Deregulation of human telomerase gene hTERT is a well-established step in leukemia development. B-acute lymphoblastic leukemia (B-ALL) recovery rates exceed 90% in children; however, the relapse rate is around 20% among treated patients, and 10% of these are still incurable. This review highlights the biological and clinical relevance of telomerase for B-ALL and the implications of its canonical and non-canonical action on signaling pathways in the context of disease and treatment. The physiological role of telomerase in lymphocytes makes the study of its biomarker potential a great challenge. Nevertheless, many works have demonstrated that high telomerase activity or hTERT expression, as well as short telomeres, correlate with poor prognosis in B-ALL. Telomerase and related proteins have been proven to be promising pharmacological targets. Likewise, combined therapy with telomerase inhibitors may turn out to be an alternative strategy for B-ALL.

Construction of a radiogenomic association map of pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic adenocarcinoma (PDAC) persists as a malignancy with high morbidity and mortality that can benefit from new means to characterize and detect these tumors, such as radiogenomics. In order to address this gap in the literature, constructed a transcriptomic-CT radiogenomic (RG) map for PDAC.

METHODS

In this Institutional Review Board approved study, a cohort of subjects (n = 50) with gene expression profile data paired with histopathologically confirmed resectable or borderline resectable PDAC were identified. Studies with pre-operative contrast-enhanced CT images were independently assessed for a set of 88 predefined imaging features. Microarray gene expression profiling was then carried out on the histopathologically confirmed pancreatic adenocarcinomas and gene networks were constructed using Weighted Gene Correlation Network Analysis (WCGNA) (n = 37). Data were analyzed with bioinformatics analyses, multivariate regression-based methods, and Kaplan-Meier survival analyses.

RESULTS

Survival analyses identified multiple features of interest that were significantly associated with overall survival, including Tumor Height (P = 0.014), Tumor Contour (P = 0.033), Tumor-stroma Interface (P = 0.014), and the Tumor Enhancement Ratio (P = 0.047). Gene networks for these imaging features were then constructed using WCGNA and further annotated according to the Gene Ontology (GO) annotation framework for a biologically coherent interpretation of the imaging trait-associated gene networks, ultimately resulting in a PDAC RG CT-transcriptome map composed of 3 stage-independent imaging traits enriched in metabolic processes, telomerase activity, and podosome assembly (P < 0.05).

CONCLUSIONS

A CT-transcriptomic RG map for PDAC composed of semantic and quantitative traits with associated biology processes predictive of overall survival, was constructed, that serves as a reference for further mechanistic studies for non-invasive phenotyping of pancreatic tumors.

Association of the Telomerase Reverse Transcriptase rs10069690 Polymorphism with the Risk, Age at Onset and Prognosis of Triple Negative Breast Cancer

Telomerase reverse transcriptase (TERT) plays a key role in the maintenance of telomere DNA length. The rs10069690 single nucleotide variant, located in intron 4 of TERT, was found to be associated with telomere length and the risk of estrogen receptor-negative but not-positive breast cancer. This study aimed at analysis of the association of rs10069690 genotype and TERT expression with the risk, age at onset, prognosis, and clinically and molecularly relevant subtypes of breast cancer. Accordingly, rs10069690 was genotyped in a hospital-based case-control study of 403 female breast cancer patients and 246 female controls of a Central European (Austrian) study population, and the mRNA levels of TERT were quantified in 106 primary breast tumors using qRT-PCR. We found that in triple-negative breast cancer patients, the minor rs10069690 TT genotype tended to be associated with an increased breast cancer risk (OR, 1.87; 95% CI, 0.75-4.71; p = 0.155) and was significantly associated with 11.7 years younger age at breast cancer onset (p = 0.0002), whereas the CC genotype was associated with a poor brain metastasis-free survival (p = 0.009). Overall, our data show that the rs10069690 CC genotype and a high TERT expression tended to be associated with each other and with a poor prognosis. Our findings indicate a key role of rs10069690 in triple-negative breast cancer.

Meta-hallmarks of aging and cancer

Both aging and cancer are characterized by a series of partially overlapping "hallmarks" that we subject here to a meta-analysis. Several hallmarks of aging (i.e., genomic instability, epigenetic alterations, chronic inflammation, and dysbiosis) are very similar to specific cancer hallmarks and hence constitute common "meta-hallmarks," while other features of aging (i.e., telomere attrition and stem cell exhaustion) act likely to suppress oncogenesis and hence can be viewed as preponderantly "antagonistic hallmarks." Disabled macroautophagy and cellular senescence are two hallmarks of aging that exert context-dependent oncosuppressive and pro-tumorigenic effects. Similarly, the equivalence or antagonism between aging-associated deregulated nutrient-sensing and cancer-relevant alterations of cellular metabolism is complex. The agonistic and antagonistic relationship between the processes that drive aging and cancer has bearings for the age-related increase and oldest age-related decrease of cancer morbidity and mortality, as well as for the therapeutic management of malignant disease in the elderly.

A telomerase regulation-related lncRNA signature predicts prognosis and immunotherapy response for gastric cancer

BACKGROUND

Telomeres are involved in the development and progression of gastric cancer (GC). However, the association of telomerase regulation-related lncRNAs with prognosis and immunotherapy responsiveness in gastric cancer is unclear.

METHODS

This study systematically evaluated the relationship between lncRNAs co-expressed with 67 telomerase regulatory genes and gastric cancer prognosis. The risk scores of the samples were calculated based on telomerase regulation-related lncRNAs with prognostic value, and the samples were classified into high-/low-risk groups. The prognostic value of risk groups was then evaluated, a GC prognostic prediction model based on risk groups and clinical characteristics was established, and the prediction accuracy of the model was clarified by receiving operating characteristic (ROC) curves and calibration curves. Finally, the value of risk grouping in GC immunotherapy sensitivity was predicted by comparing MSI status and tumor mutation load between the high- and low-risk groups.

RESULTS

We identified 13 lncRNAs with prognostic value co-expressed with telomerase regulatory genes and observed that the prognosis of the low-risk group was significantly better than that of the high-risk group. Meanwhile, a GC overall survival (OS) prediction model based on risk grouping and clinical characteristics was developed, and ROC curves and calibration curves confirmed the good predictive ability of the model. In addition, the low-risk group exhibited a higher tumor mutation load and MSI-H, suggesting a possible benefit of immunotherapy.

CONCLUSION

We found that telomerase regulation-related lncRNAs have prognostic value in GC patients and contribute to the exploration of more effective immunotherapeutic strategies.

Subcellular localization of hTERT in breast cancer: insights into its tumorigenesis and drug resistance mechanisms in HER2-immunopositive breast cancer

Human telomerase reverse transcriptase (hTERT) is highly expressed in various cancers, including breast cancer. Although telomere elongation is an essential role for hTERT, the nuclear export after oxdative stress has also been shown in several cancer cell lines and is associated with drug-resistance in vitro. As only a few reports focused on the subcellular localization of hTERT in clinical specimens, we performed immunohistochemistry (IHC) and analyzed the correlation between intracellular hTERT expression and the clinicopathological characteristics to identify the clinical significance of hTERT subcellular expression in breast cancers. 144 invasive breast cancers classified by IHC subtype without primary systemic therapy (PST), were selected from a surgical resection cohort and were immunostained for hTERT, p-STAT3, p-AKT and p-ERK. The nuclear and/or cytoplasmic staining intensity and proportion of hTERT were scored and compared with clinicopathological parameters. The nuclear hTERT expression was significantly correlated with HER2 expression (p = 0.00156), and the scores were significantly correlated with p-STAT3 and p-AKT expression scores (r = 0.532, p = 0.000587 and r = 0.345, p = 0.0339, respectively) in the HER2-immunopositive breast cancer including luminal-HER2 and HER2 subtypes. Furthermore, hTERT was expressed more in cytoplasm in the specimens after PST than those before PST, and the score tended to be negatively correlated with tumor shrinkage rate in HER2 subtype (r = -0.593, p = 0.0705). These results suggest that nuclear and/or cytoplasmic hTERT may play a different role before and after PST including the tumorigenesis and drug-resistance in breast cancer. Suppression of cytoplasmic hTERT expression may lead to more effective strategy for drug-resistant HER2 subtype in breast cancer.

The role of transketolase in human cancer progression and therapy

Transketolase (TKT) is an enzyme that is ubiquitously expressed in all living organisms and has been identified as an important regulator of cancer. Recent studies have shown that the TKT family includes the TKT gene and two TKT-like (TKTL) genes; TKTL1 and TKTL2. TKT and TKTL1 have been reported to be involved in the regulation of multiple cancer-related events, such as cancer cell proliferation, metastasis, invasion, epithelial-mesenchymal transition, chemoradiotherapy resistance, and patient survival and prognosis. Therefore, TKT may be an ideal target for cancer treatment. More importantly, the levels of TKTL1 were detected using EDIM technology for the early detection of some malignancies, and TKTL1 was more sensitive and specific than traditional tumor markers. Detecting TKTL1 levels before and after surgery could be used to evaluate the surgery's effect. While targeted TKT suppresses cancer in multiple ways, in some cases, it has detrimental effects on the organism. In this review, we discuss the role of TKT in different tumors and the detailed mechanisms while evaluating its value and limitations in clinical applications. Therefore, this review provides a basis for the clinical application of targeted therapy for TKT in the future, and a strategy for subsequent cancer-related research.

Telomere Dysfunction Is Associated with Altered DNA Organization in Trichoplein/Tchp/Mitostatin (TpMs) Depleted Cells

Recently, we highlighted a novel role for the protein Trichoplein/TCHP/Mitostatin (TpMs), both as mitotic checkpoint regulator and guardian of chromosomal stability. TpMs-depleted cells show numerical and structural chromosome alterations that lead to genomic instability. This condition is a major driving force in malignant transformation as it allows for the cells acquiring new functional capabilities to proliferate and disseminate. Here, the effect of TpMs depletion was investigated in different TpMs-depleted cell lines by means of 3D imaging and 3D Structured illumination Microscopy. We show that TpMs depletion causes alterations in the 3D architecture of telomeres in colon cancer HCT116 cells. These findings are consistent with chromosome alterations that lead to genomic instability. Furthermore, TpMs depletion changes the spatial arrangement of chromosomes and other nuclear components. Modified nuclear architecture and organization potentially induce variations that precede the onset of genomic instability and are considered as markers of malignant transformation. Our present observations connect the tumor suppression ability of TpMs with its novel functions in maintaining the proper chromosomal segregation as well as the proper telomere and nuclear architecture. Further investigations will investigate the connection between alterations in telomeres and nuclear architecture with the progression of human tumors with the aim of developing personalized therapeutic interventions.

Metabolic Reprogramming in Cancer Cells: Emerging Molecular Mechanisms and Novel Therapeutic Approaches

The constant changes in cancer cell bioenergetics are widely known as metabolic reprogramming. Reprogramming is a process mediated by multiple factors, including oncogenes, growth factors, hypoxia-induced factors, and the loss of suppressor gene function, which support malignant transformation and tumor development in addition to cell heterogeneity. Consequently, this hallmark promotes resistance to conventional anti-tumor therapies by adapting to the drastic changes in the nutrient microenvironment that these therapies entail. Therefore, it represents a revolutionary landscape during cancer progression that could be useful for developing new and improved therapeutic strategies targeting alterations in cancer cell metabolism, such as the deregulated mTOR and PI3K pathways. Understanding the complex interactions of the underlying mechanisms of metabolic reprogramming during cancer initiation and progression is an active study field. Recently, novel approaches are being used to effectively battle and eliminate malignant cells. These include biguanides, mTOR inhibitors, glutaminase inhibition, and ion channels as drug targets. This review aims to provide a general overview of metabolic reprogramming, summarise recent progress in this field, and emphasize its use as an effective therapeutic target against cancer.

Relative Telomere Length Change in Colorectal Carcinoma and Its Association with Tumor Characteristics, Gene Expression and Microsatellite Instability

We compared tumor and adjacent normal tissue samples from 165 colorectal carcinoma (CRC) patients to study change in relative telomere length (RTL) and its association with different histological and molecular features. To measure RTL, we used a Luminex-based assay. We observed shorter RTL in the CRC tissue compared to paired normal tissue (RTL 0.722 ± SD 0.277 vs. 0.809 ± SD 0.242, p = 0.00012). This magnitude of RTL shortening (by ~0.08) in tumor tissue is equivalent to RTL shortening seen in human leukocytes over 10 years of aging measured by the same assay. RTL was shorter in cancer tissue, irrespective of age group, gender, tumor pathology, location and microsatellite instability (MSI) status. RTL shortening was more prominent in low-grade CRC and in the presence of microsatellite instability (MSI). In a subset of patients, we also examined differential gene expression of (a) telomere-related genes, (b) genes in selected cancer-related pathways and (c) genes at the genome-wide level in CRC tissues to determine the association between gene expression and RTL changes. RTL shortening in CRC was associated with (a) upregulation of DNA replication genes, cyclin dependent-kinase genes (anti-tumor suppressor) and (b) downregulation of "caspase executor", reducing apoptosis.