Alternative splicing is a developmental switch for hTERT expression.

Telomere length control is critical for cellular lifespan and tumor suppression. Telomerase is transiently activated in the inner cell mass of the developing blastocyst to reset telomere reserves. Its silencing upon differentiation leads to gradual telomere shortening in somatic cells. Here, we report that transcriptional regulation through cis-regulatory elements only partially accounts for telomerase activation in pluripotent cells. Instead, developmental control of telomerase is primarily driven by an alternative splicing event, centered around hTERT exon 2. Skipping of exon 2 triggers hTERT mRNA decay in differentiated cells, and conversely, its retention promotes telomerase accumulation in pluripotent cells. We identify SON as a regulator of exon 2 alternative splicing and report a patient carrying a SON mutation and suffering from insufficient telomerase and short telomeres. In summary, our study highlights a critical role for hTERT alternative splicing in the developmental regulation of telomerase and implicates defective splicing in telomere biology disorders.

DDB2 promotes melanoma cell growth by transcriptionally regulating the expression of KMT2A and predicts a poor prognosis.

Identification of potential key targets of melanoma, a fatal skin malignancy, is critical to the development of new cancer therapies. Lysine methyltransferase 2A (KMT2A) promotes melanoma growth by activating the human telomerase reverse transcriptase (hTERT) signaling pathway; however, the exact mechanism remains elusive. This study aimed to reveal new molecular targets that regulate KMT2A expression and melanoma growth. Using biotin-streptavidin-agarose pull-down and proteomics, we identified Damage-specific DNA-binding protein 2 (DDB2) as a KMT2A promoter-binding protein in melanoma cells and validated its role as a regulator of KMT2A/hTERT signaling. DDB2 knockdown inhibited the expression of KMT2A and hTERT and inhibited the growth of melanoma cells in vitro. Conversely, overexpression of DDB2 activated the expression of KMT2A and promoted the growth of melanoma cells. Additionally, we demonstrated that DDB2 expression was higher in tumor tissues of patients with melanoma than in corresponding normal tissues and was positively correlated with KMT2A expression. Kaplan-Meier analysis showed a poor prognosis in patients with high levels of DDB2 and KMT2A. Overall, our data suggest that DDB2 promotes melanoma cell growth through the transcriptional regulation of KMT2A expression and predicts poor prognosis. Therefore, targeting DDB2 may regulate the effects of KMT2A on melanoma growth and progression, providing a new potential therapeutic strategy for melanoma.

Noncanonical functions of telomerase and telomeres in viruses-associated cancer.

The cause of cancer is attributed to the uncontrolled growth and proliferation of cells resulting from genetic changes and alterations in cell behavior, a phenomenon known as epigenetics. Telomeres, protective caps on the ends of chromosomes, regulate both cellular aging and cancer formation. In most cancers, telomerase is upregulated, with the telomerase reverse transcriptase (TERT) enzyme and telomerase RNA component (TERC) RNA element contributing to the maintenance of telomere length. Additionally, it is noteworthy that two viruses, human papillomavirus (HPV) and Epstein-Barr virus (EBV), utilize telomerase for their replication or persistence in infected cells. Also, TERT and TERC may play major roles in cancer not related to telomere biology. They are involved in the regulation of gene expression, signal transduction pathways, cellular metabolism, or even immune response modulation. Furthermore, the crosstalk between TERT, TERC, RNA-binding proteins, and microRNAs contributes to a greater extent to cancer biology. To understand the multifaceted roles played by TERT and TERC in cancer and viral life cycles, and then to develop effective therapeutic strategies against these diseases, are fundamental for this goal. By investigating deeply, the complicated mechanisms and relationships between TERT and TERC, scientists will open the doors to new therapies. In its analysis, the review emphasizes the significance of gaining insight into the multifaceted roles that TERT and TERC play in cancer pathogenesis, as well as their involvement in the viral life cycle for designing effective anticancer therapy approaches.

Human artificial chromosome carrying 3p21.3-p22.2 region suppresses hTERT transcription in oral cancer cells.

Telomerase is a ribonucleoprotein ribonucleic enzyme that elongates telomere repeat sequences at the ends of chromosomes and contributes to cellular immortalization. The catalytic component of telomerase, human telomerase reverse transcriptase (hTERT), has been observed to be reactivated in immortalized cells. Notably, most cancer cells have been found to have active hTERT mRNA transcription, resulting in continuous cell division, which is crucial for malignant transformation. Therefore, discovering mechanisms underlying the regulation of hTERT transcription is an attractive target for cancer-specific treatments.Loss of heterozygosity (LOH) of chromosome 3p21.3 has been frequently observed in human oral squamous cell carcinoma (OSCC). Moreover, we previously reported that HSC3 OSCC microcell hybrid clones with an introduced human chromosome 3 (HSC3#3) showed inhibition of hTERT transcription compared with the parental HSC3 cells. This study examined whether hTERT transcription regulators are present in the 3p21.3 region. We constructed a human artificial chromosome (HAC) vector (3p21.3-HAC) with only the 3p21.3-p22.2 region and performed functional analysis using the 3p21.3-HAC. HSC3 microcell hybrid clones with an introduced 3p21.3-HAC exhibited significant suppression of hTERT transcription, similar to the microcell hybrid clones with an intact chromosome 3. In contrast, HSC3 clones with truncated chromosome 3 with deletion of the 3p21.3 region (3delp21.3) showed no effect on hTERT expression levels. These results provide direct evidence that hTERT suppressor gene(s) were retained in the 3p21.3 region, suggesting that the presence of regulatory factors that control telomerase enzyme activity may be involved in the development of OSCC.

Association between human telomerase reverse transcriptase (hTERT) MNS16A polymorphism and risk of breast cancer.

BACKGROUND: It is well known that telomerase activity is suppressed in normal human tissues and reactivated in tumors, suggesting that the human telomerase reverse transcriptase (hTERT, MIM: 187270) gene may be involved in carcinogenesis. A polymorphic tandem repeat minisatellite located downstream of exon 16 of hTERT and upstream in the putative promoter region of an antisense hTERT transcript, termed MNS16A, results in a functional polymorphism. Because the association between the MNS16A genetic polymorphism and breast cancer (BC) risk remains an open question, the present case-control study was conducted in Shiraz (Fars Province, Southern Iran). METHODS: A total of 711 samples were collected, including 362 BC patients and 349 healthy individuals. Genotyping was performed by polymerase chain reaction method. Alleles were determined by classifying DNA amplicons of less than and greater than 300 bp as short (S) and long (L) alleles, respectively. RESULTS: Different inheritance models (codominant, dominant, recessive, overdominant genotype models and the allele model) were used to evaluate the association between the MNS16A polymorphism and the risk of BC. No significant association was observed in any of the analyses. It should be noted that the statistical power of the comparisons was low. CONCLUSION: The present study did not support the association between hTERT MNS16A polymorphism and breast cancer risk. Similar studies in other populations with larger sample sizes are needed to determine the association between the hTERT MNS16A polymorphism and susceptibility to breast cancer.

Safety and dose escalation of the targeted oncolytic adenovirus OBP-301 for refractory advanced liver cancer: Phase I clinical trial.

OBP-301 is an oncolytic adenovirus modified to replicate within cancer cells and lyse them. This open-label, non-comparative, phase I dose-escalation trial aimed to assess its safety and optimal dosage in 20 patients with advanced hepatocellular carcinoma. Good tolerance was shown with a maximum tolerated dose of 6 × 1012 viral particles. The most common treatment-emergent adverse events were influenza-like illness, pyrexia, fatigue, decreased platelet count, abdominal distension, and anemia. Cohorts 4 and 5 had approximately 50% higher levels of CD8+ T cells in the peripheral blood after injection. The best target response occurred in 14 patients, 4 of whom had progressive disease. Multiple intratumoral injections of OBP-301 were well tolerated in patients with advanced hepatocellular carcinoma. The stable disease rate for the injected tumors was greater than the overall response rate, even with no obvious tumor response. OBP-301 might have a greater impact on local response as histological examination revealed that the presence of OBP-301 was consistent with the necrotic area at the injection site. Increased infiltration of CD8+ T cells and <1% PD-L1 expression were observed in tumors after injection. Improved antitumor efficacy might be achieved in future studies via viral injection with volume adjustment and in combination with other immuno-therapeutics.

Obesity-Senescence-Breast Cancer: Clinical Presentation of a Common Unfortunate Cycle.

There are few convincing studies establishing the relationship between endogenous factors that cause obesity, cellular aging, and telomere shortening. Without a functional telomerase, a cell undergoing cell division has progressive telomere shortening. While obesity influences health and longevity as well as telomere dynamics, cellular senescence is one of the major drivers of the aging process and of age-related disorders. Oxidative stress induces telomere shortening, while decreasing telomerase activity. When progressive shortening of telomere length reaches a critical point, it triggers cell cycle arrest leading to senescence or apoptotic cell death. Telomerase activity cannot be detected in normal breast tissue. By contrast, maintenance of telomere length as a function of human telomerase is crucial for the survival of breast cancer cells and invasion. Approximately three-quarters of breast cancers in the general population are hormone-dependent and overexpression of estrogen receptors is crucial for their continued growth. In obesity, increasing leptin levels enhance aromatase messenger ribonucleic acid (mRNA) expression, aromatase content, and its enzymatic activity on breast cancer cells, simultaneously activating telomerase in a dose-dependent manner. Meanwhile, applied anti-estrogen therapy increases serum leptin levels and thus enhances leptin resistance in obese postmenopausal breast cancer patients. Many studies revealed that shorter telomeres of postmenopausal breast cancer have higher local recurrence rates and higher tumor grade. In this review, interlinked molecular mechanisms are looked over between the telomere length, lipotoxicity/glycolipotoxicity, and cellular senescence in the context of estrogen receptor alpha-positive (ERα+) postmenopausal breast cancers in obese women. Furthermore, the effect of the potential drugs, which are used for direct inhibition of telomerase and the inhibition of human telomerase reverse transcriptase (hTERT) or human telomerase RNA promoters as well as approved adjuvant endocrine therapies, the selective estrogen receptor modulator and selective estrogen receptor down-regulators are discussed.

Polymorphic tandem DNA repeats activate the human telomerase reverse transcriptase gene.

Multiple independent sequence variants of the hTERT locus have been associated with telomere length and cancer risks in genome-wide association studies. Here, we identified an intronic variable number tandem repeat, VNTR2-1, as an enhancer-like element, which activated hTERT transcription in a cell in a chromatin-dependent manner. VNTR2-1, consisting of 42-bp repeats with an array of enhancer boxes, cooperated with the proximal promoter in the regulation of hTERT transcription by basic helix-loop-helix transcription factors and maintained hTERT expression during embryonic stem-cell differentiation. Genomic deletion of VNTR2-1 in MelJuSo melanoma cells markedly reduced hTERT transcription, leading to telomere shortening, cellular senescence, and impairment of xenograft tumor growth. Interestingly, VNTR2-1 lengths varied widely in human populations; hTERT alleles with shorter VNTR2-1 were underrepresented in African American centenarians, indicating its role in human aging. Therefore, this polymorphic element is likely a missing link in the telomerase regulatory network and a molecular basis for genetic diversities of telomere homeostasis and age-related disease susceptibilities.

TRIM28 is a transcriptional activator of the mutant TERT promoter in human bladder cancer.

Bladder cancer (BC) has a 70% telomerase reverse transcriptase (TERT or hTERT in humans) promoter mutation prevalence, commonly at -124 base pairs, and this is associated with increased hTERT expression and poor patient prognosis. We inserted a green fluorescent protein (GFP) tag in the mutant hTERT promoter allele to create BC cells expressing an hTERT-GFP fusion protein. These cells were used in a fluorescence-activated cell sorting-based pooled CRISPR-Cas9 Kinome knockout genetic screen to identify tripartite motif containing 28 (TRIM28) and TRIM24 as regulators of hTERT expression. TRIM28 activates, while TRIM24 suppresses, hTERT transcription from the mutated promoter allele. TRIM28 is recruited to the mutant promoter where it interacts with TRIM24, which inhibits its activity. Phosphorylation of TRIM28 through the mTOR complex 1 (mTORC1) releases it from TRIM24 and induces hTERT transcription. TRIM28 expression promotes in vitro and in vivo BC cell growth and stratifies BC patient outcome. mTORC1 inhibition with rapamycin analog Ridaforolimus suppresses TRIM28 phosphorylation, hTERT expression, and cell viability. This study may lead to hTERT-directed cancer therapies with reduced effects on normal progenitor cells.

Association of hTERT Gene Polymorphism and Colorectal Cancer (CRC) Risk in the Chinese Han Population.

The catalytic subunit telomerase reverse transcriptase (hTERT) is a prerequisite for malignant transformation of human cells. Colorectal cancer (CRC) is a common malignant tumor. The genetic association of hTERT gene rs2853669 and rs2736098 polymorphisms with CRC was surveyed in the Chinese population. Two hundreds patients with CRC and 200 healthy controls were taken for blood sample collection. Sanger sequencing was applied for genotyping. Multiple logistic regression analysis was performed, and odds ratio (OR) together with confidence interval (CI) were calculated to obtain the corresponding association power. Among CRC cases (49.50%), hTERT gene rs2736098 GA genotype carriers were more prevalent compared with the control group (41.00%, P = 0.035), which increased the risk of CRC by 1.576 times (95% CI, 1.031-2.409). Distribution of the rs2736098 genotypes was significantly associated with TNM stage, tumor differentiation, tumor size and lymph node metastasis (P < 0.05). The frequencies of hTERT gene rs2853669 polymorphism were not significantly different between CRC patients and healthy controls. Logistic regression analysis indicated that both body mass index (BMI) and hTERT gene rs2736098 polymorphism remained significantly correlated with CRC susceptibility. The frequencies of hTERT gene rs2853669 polymorphism did not differ significantly between CRC patients and control group (P > 0.05). The hTERT gene rs2736098 polymorphism was correlated with CRC risk in the Chinese Han population, and the GA genotype was a risk element for the onset of CRC.

hTERT Epigenetics Provides New Perspectives for Diagnosis and Evidence-Based Guidance of Chemotherapy in Cancer.

Strong epigenetic pan-cancer biomarkers are required to meet several current, urgent clinical needs and to further improve the present chemotherapeutic standard. We have concentrated on the investigation of epigenetic alteration of the hTERT gene, which is frequently epigenetically dysregulated in a number of cancers in specific developmental stages. Distinct DNA methylation profiles were identified in our data on early urothelial cancer. An efficient EpihTERT assay could be developed utilizing suitable combinations with sequence-dependent thermodynamic parameters to distinguish between differentially methylated states. We infer from this data set, the epigenetic context, and the related literature that a CpG-rich, 2800 bp region, a prominent CpG island, surrounding the transcription start of the hTERT gene is the crucial epigenetic zone for the development of a potent biomarker. In order to accurately describe this region, we have named it "Acheron" (Ἀχέρων). In Greek mythology, this is the river of woe and misery and the path to the underworld. Exploitation of the DNA methylation profiles focused on this region, e.g., idiolocal normalized Methylation Specific PCR (IDLN-MSP), opens up a wide range of new possibilities for diagnosis, determination of prognosis, follow-up, and detection of residual disease. It may also have broad implications for the choice of chemotherapy.

Advancements in Telomerase-Targeted Therapies for Glioblastoma: A Systematic Review.

Glioblastoma (GBM) is a primary CNS tumor that is highly lethal in adults and has limited treatment options. Despite advancements in understanding the GBM biology, the standard treatment for GBM has remained unchanged for more than a decade. Only 6.8% of patients survive beyond five years. Telomerase, particularly the hTERT promoter mutations present in up to 80% of GBM cases, represents a promising therapeutic target due to its role in sustaining telomere length and cancer cell proliferation. This review examines the biology of telomerase in GBM and explores potential telomerase-targeted therapies. We conducted a systematic review following the PRISMA-P guidelines in the MEDLINE/PubMed and Scopus databases, from January 1995 to April 2024. We searched for suitable articles by utilizing the terms "GBM", "high-grade gliomas", "hTERT" and "telomerase". We incorporated studies addressing telomerase-targeted therapies into GBM studies, excluding non-English articles, reviews, and meta-analyses. We evaluated a total of 777 records and 46 full texts, including 36 studies in the final review. Several compounds aimed at inhibiting hTERT transcription demonstrated promising preclinical outcomes; however, they were unsuccessful in clinical trials owing to intricate regulatory pathways and inadequate pharmacokinetics. Direct hTERT inhibitors encountered numerous obstacles, including a prolonged latency for telomere shortening and the activation of the alternative lengthening of telomeres (ALT). The G-quadruplex DNA stabilizers appeared to be potential indirect inhibitors, but further clinical studies are required. Imetelstat, the only telomerase inhibitor that has undergone clinical trials, has demonstrated efficacy in various cancers, but its efficacy in GBM has been limited. Telomerase-targeted therapies in GBM is challenging due to complex hTERT regulation and inadequate inhibitor pharmacokinetics. Our study demonstrates that, despite promising preclinical results, no Telomerase inhibitors have been approved for GBM, and clinical trials have been largely unsuccessful. Future strategies may include Telomerase-based vaccines and multi-target inhibitors, which may provide more effective treatments when combined with a better understanding of telomere dynamics and tumor biology. These treatments have the potential to be integrated with existing ones and to improve the outcomes for patients with GBM.

Crosstalk between BER and NHEJ in XRCC4-Deficient Cells Depending on hTERT Overexpression.

Targeting DNA repair pathways is an important strategy in anticancer therapy. However, the unrevealed interactions between different DNA repair systems may interfere with the desired therapeutic effect. Among DNA repair systems, BER and NHEJ protect genome integrity through the entire cell cycle. BER is involved in the repair of DNA base lesions and DNA single-strand breaks (SSBs), while NHEJ is responsible for the repair of DNA double-strand breaks (DSBs). Previously, we showed that BER deficiency leads to downregulation of NHEJ gene expression. Here, we studied BER's response to NHEJ deficiency induced by knockdown of NHEJ scaffold protein XRCC4 and compared the knockdown effects in normal (TIG-1) and hTERT-modified cells (NBE1). We investigated the expression of the XRCC1, LIG3, and APE1 genes of BER and LIG4; the Ku70/Ku80 genes of NHEJ at the mRNA and protein levels; as well as p53, Sp1 and PARP1. We found that, in both cell lines, XRCC4 knockdown leads to a decrease in the mRNA levels of both BER and NHEJ genes, though the effect on protein level is not uniform. XRCC4 knockdown caused an increase in p53 and Sp1 proteins, but caused G1/S delay only in normal cells. Despite the increased p53 protein, p21 did not significantly increase in NBE1 cells with overexpressed hTERT, and this correlated with the absence of G1/S delay in these cells. The data highlight the regulatory function of the XRCC4 scaffold protein and imply its connection to a transcriptional regulatory network or mRNA metabolism.

Telomerase activity and hTERT gene expression in patients with acute coronary syndrome and stable coronary artery disease.

BACKGROUND: In this study, we aimed to examine the telomerase activity and hTERT gene expression in patients with acute coronary syndrome (ACS) and those with stable coronary artery disease (SCAD) and compare the results to controls. Additionally, we compared overall mortality rates relative to the telomerase activity. METHODS: A total of 211 patients (78 ACS and 71 SCAD patients) were included in the study. The telomerase concentration was measured by ELISA and used to determine telomerase activity. The hTERT gene expression was determined by real-time PCR. RESULTS: The serum telomerase enzyme concentration was lower in ACS (36.61 ± 1.54) and SCAD (36.79 ± 1.57) when compared to the control group (37.03 ± 2.25). However, this difference did not reach statistical significance (p = 0.890). The hTERT gene expression acting in telomerase enzyme synthesis was 2.7-fold lower in ACS group (p = 0.070) and 2.2-fold lower in the SCAD group (p = 0.101) compared to the control group. Patients were followed for a median of 32 months (minimum: 0.1, maximum: 46.8). The serum telomerase concentrations in patients who died and those survived in the SCAD group (35.98 ± 2.02 vs 36.86 ± 1.52 ng/ml, respectively; p = 0.529) were similar to those in the ACS group (36.39 ± 1.08 vs 36.63 ± 1.60 ng/ml, respectively p = 0.993). CONCLUSIONS: In the current study, telomerase activity or hTERT expression was similar in patients with ACS, SCAD, and controls. Moreover, telomerase activity was not associated with all- cause mortality during the 32-month follow-up (Tab. 3, Fig. 1, Ref. 29).

Telomerase inhibition in malignant gliomas: a systematic review.

Glioblastoma (GBM) is the most frequent adult malignant brain tumour and despite different therapeutic efforts, the median overall survival still ranges from 14 to 18 months. Thus, new therapeutic strategies are urgently needed. However, the identification of cancer-specific targets is particularly challenging in GBM, due to the high heterogeneity of this tumour in terms of histopathological, molecular, genetic and epigenetic features. Telomerase reactivation is a hallmark of malignant glioma. An activating mutation of the hTERT gene, encoding for the active subunit of telomerase, is one of the molecular criteria to establish a diagnosis of GBM, IDH-wildtype, in the 2021 WHO classification of central nervous system tumours. Telomerase inhibition therefore represents, at least theoretically, a promising strategy for GBM therapy: pharmacological compounds, as well as direct gene expression modulation therapies, have been successfully employed in in vitro and in vivo settings. Unfortunately, the clinical applications of telomerase inhibition in GBM are currently scarce. The aim of the present systematic review is to provide an up-to-date report on the studies investigating telomerase inhibition as a therapeutic strategy for malignant glioma in order to foster the future translational and clinical research on this topic.

Lyon IARC Polyomavirus Displays Transforming Activities in Primary Human Cells.

Several studies reported the presence of a recently discovered polyomavirus (PyV), Lyon IARC PyV (LIPyV), in human and domestic animal specimens. LIPyV has some structural similarities to well-established animal and human oncogenic PyVs, such as raccoon PyV and Merkel cell PyV (MCPyV), respectively. In this study, we demonstrate that LIPyV early proteins immortalize human foreskin keratinocytes. LIPyV LT binds pRb, accordingly cell cycle checkpoints are altered in primary human fibroblasts and keratinocytes expressing LIPyV early genes. Mutation of the pRb binding site in LT strongly affected the ability of LIPyV ER to induced HFK immortalization. LIPyV LT also binds p53 and alters p53 functions activated by cellular stresses. Finally, LIPyV early proteins activate telomerase reverse transcriptase (hTERT) gene expression, via accumulation of the Sp1 transcription factor. Sp1 recruitment to the hTERT promoter is controlled by its phosphorylation, which is mediated by ERK1 and CDK2. Together, these data highlight the transforming properties of LIPyV in in vitro experimental models, supporting its possible oncogenic nature. IMPORTANCE Lyon IARC PyV is a recently discovered polyomavirus that shows some structural similarities to well-established animal and human oncogenic PyVs, such as raccoon PyV and Merkel cell PyV, respectively. Here, we show the capability of LIPyV to efficiently promote cellular transformation of primary human cells, suggesting a possible oncogenic role of this virus in domestic animals and/or humans. Our study identified a novel virus-mediated mechanism of activation of telomerase reverse transcriptase gene expression, via accumulation of the Sp1 transcription factor. In addition, because the persistence of infection is a key event in virus-mediated carcinogenesis, it will be important to determine whether LIPyV can deregulate immune-related pathways, similarly to the well-established oncogenic viruses.

Circulating tumor cells (CTCs) and hTERT gene expression in CTCs for radiotherapy effect with lung cancer.

BACKGROUND: Circulating tumor cells (CTCs) are important biological indicators of the lung cancer prognosis, and CTC counting and typing may provide helpful biological information for the diagnosis and treatment of lung cancer. METHODS: The CTC count in blood before and after radiotherapy was detected by the CanPatrol™ CTC analysis system, and the CTC subtypes and the expression of hTERT before and after radiotherapy were detected by multiple in situ hybridization. The CTC count was calculated as the number of cells per 5 mL of blood. RESULTS: The CTC positivity rate in patients with tumors before radiotherapy was 98.44%. Epithelial-mesenchymal CTCs (EMCTCs) were more common in patients with lung adenocarcinoma and squamous carcinoma than in patients with small cell lung cancer (P = 0.027). The total CTCs (TCTCs), EMCTCs, and mesenchymal CTCs (MCTCs) counts were significantly higher in patients with TNM stage III and IV tumors (P < 0.001, P = 0.005, and P < 0.001, respectively). The TCTCs and MCTCs counts were significantly higher in patients with an ECOG score of > 1 (P = 0.022 and P = 0.024, respectively). The TCTCs and EMCTCs counts before and after radiotherapy affected the overall response rate (ORR) (P < 0.05). TCTCs and ECTCs with positive hTERT expression were associated with the ORR of radiotherapy (P = 0.002 and P = 0.038, respectively), as were TCTCs with high hTERT expression (P = 0.012). ECOG score (P = 0.006) and post-radiation TCTCs count (P = 0.011) were independent factors for progression-free survival (PFS) and TNM stage (P = 0.054) and pre-radiation EMCTCs count (P = 0.009) were independent factors of overall survival (OS). CONCLUSION: This study showed a high rate of positive CTC detection in patients with lung cancer, and the number, subtype, and hTERT-positive expression of CTCs were closely related to patients' ORR, PFS, and OS with radiotherapy. EMCTCs, hTERT-positive expression of CTCs are expected to be important biological indicators for predicting radiotherapy efficacy and the prognosis in patients with lung cancer. These results may be useful in improving disease stratification for future clinical trials and may help in clinical decision-making.

Phosphorylation of hTERT at threonine 249 is a novel tumor biomarker of aggressive cancer with poor prognosis in multiple organs.

Recent evidence indicates that RNA-dependent RNA polymerase (RdRP) activity of human telomerase reverse transcriptase (hTERT) regulates expression of target genes and is directly involved in tumor formation in a telomere-independent manner. Non-canonical function of hTERT has been considered as a therapeutic target for cancer therapy. We have previously shown that hTERT phosphorylation at threonine 249 (p-hTERT), which promotes RdRP activity, is an indicator of an aggressive phenotype and poor prognosis in liver and pancreatic cancers, using two cohorts with small sample sizes with polyclonal p-hTERT antibody. To clarify the clinical relevance of p-hTERT, we developed a specific monoclonal antibody and determined the diagnostic and prognostic value of p-hTERT in cancer specimens using a large cohort. A monoclonal antibody for phosphorylated hTERT (p-hTERT) at threonine 249 was developed and validated. The antibody was used for the immunohistochemical staining of formalin-fixed, paraffin-embedded specimens from 1523 cases of lung, colon, stomach, pancreatic, liver, breast, and kidney cancers. We detected elevated p-hTERT expression levels in cases with a high mitotic activity, high pathological grade, and high nuclear pleomorphism. Elevated p-hTERT expression was an independent prognostic factor for lung, pancreatic, and liver cancers. Furthermore, p-hTERT expression was associated with immature and aggressive features, such as adenosquamous carcinoma (lung and pancreas), invasive type of cancer (lung), high serum alpha-fetoprotein level (liver), and triple-negative status (breast). In conclusion, RdRP activity indicated by p-hTERT expression predicts aggressive cancer phenotypes in various types of cancer. Thus, p-hTERT is a novel biomarker for the diagnosis of aggressive cancers with a poor prognosis. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

The effect of natural polyphenols Resveratrol, Gallic acid, and Kuromanin chloride on human telomerase reverse transcriptase (hTERT) expression in HepG2 hepatocellular carcinoma: role of SIRT1/Nrf2 signaling pathway and oxidative stress.

BACKGROUND: There is evidence that low doses or physiological concentrations of certain natural polyphenols enhance the activity of telomerase. However, the precise mechanism by which natural polyphenols regulate telomerase activity remains unclear. Recent research indicates that NF-E2 related factor 2 (Nrf2) and silent information regulator 1 (SIRT1) are involved in human telomerase reverse transcriptase (hTERT) regulation. Thus, in order to better comprehend the mechanism by which polyphenols regulate hTERT, the present study investigated the effects of the natural polyphenols Resveratrol, Gallic acid, and Kuromanin chloride on hTERT, Nrf2, and SIRT1 expression as well as oxidative stress in HepG2 hepatocellular carcinoma. METHODS: The trypan blue dye exclusion assay was used to assess cell viability. The level of mRNA for hTERT, Nrf2, and SIRT1 was then determined using real-time PCR. A spectrophotometric analysis was conducted to quantify oxidative stress markers. RESULTS: The results demonstrated that Resveratrol induces the expression of hTERT and the SIRT1/Nrf2 pathway in a dose-dependent manner. Gallic acid at concentrations of 10 and 20 µM also increased the expression of the hTERT and SIRT1/Nrf2 pathway. Furthermore, dose-dependent overexpression of hTERT and Nrf2 was induced by Kuromanin chloride at 10 and 20 µM. Moreover, we found that Resveratrol and Kuromanin chloride ameliorated oxidative stress, whereas Gallic acid exacerbated it. CONCLUSIONS: This study demonstrates that low doses of polyphenols (Resveratrol, Gallic acid, and Kuromanin chloride) upregulate the expression of the hTERT gene in the HepG2 hepatocellular carcinoma cell line, possibly via induction of the SIRT1/Nrf2 signaling pathway. Therefore, by targeting this pathway or hTERT, the anti-cancer effect of polyphenols can be enhanced.

Differential Expression of the hTERT Gene in Umbilical Cord-Derived Mesenchymal Stem Cells Cocultured with B Cell Precursor Leukemia Cell Microparticles or CD41+/CD61+ Platelet Microparticles.

Several investigations are being done to increase the short lifetime of mesenchymal stem cells (MSCs). One of the crucial genes involved in the immortalization of MSCs, hTERT (human telomerase reverse transcriptase), is activated in most publications using viral-based techniques. In this work, we investigated the use of platelet-derived (PMPs) and B cell precursor leukemia-derived microparticles as a nonviral method to trigger and compare the expression of the hTERT gene in MSCs. MSCs were extracted from the umbilical cord for the current investigation and identified using a flow cytometry approach and an inverted microscope. The Nalm-6 cell line and platelet concentrate were used to isolate microparticles (MPs). MSCs and MPs were cocultured for 14 days at 25-, 50-, and 100 µg/ml concentrations. qRT-PCR was used to research the expression of the hTERT gene. SPSS 26.0's t test was used to compare the outcomes. After coculture with platelet MPs, MSCs had higher levels of hTERT gene expression than the control group. In contrast, this gene's expression was concurrently decreased in MSCs exposed to MPs generated from Nalm-6. We demonstrated that following 14-day treatment, PMP significantly boosted the hTERT gene expression in MSCs, while the Nalm-6 MPs lowered the gene expression. However, additional studies are necessary due to the stability of hTERT gene expression and the immortalization of MSCs following exposure.