Measurement Of Telomerase Activity Research Articles

Discovery of telomerase inhibitors: existing strategies and emerging innovations.

Telomerase, crucial for maintaining telomere length, is an attractive target for cancer therapy due to its role in cellular immortality. Despite three decades of research efforts, no small-molecule telomerase inhibitors have been clinically approved, highlighting the extensive challenges in developing effective telomerase-based therapeutics. This review examines conventional and emerging methods to measure telomerase activity and discusses existing inhibitors, including oligonucleotides and small molecules. Furthermore, this review highlights recent breakthroughs in structural studies of telomerase using cryo-electron microscopy, which can facilitate improved structure-based drug design. Altogether, advancements in structural methodologies and high-throughput screening offer promising prospects for telomerase-based cancer therapeutic development.

The Effect of Telomerase Enzyme on Cell Aging and Cancer Formation-Treatment

Research has made the effects of the telomerase enzyme on both cellular ageing and cancer even more important. Measurement of telomerase activity appears to be a unique marker in addition to known methods for cancer diagnosis and treatment. In addition, numerous studies have shown that the reduction of telomeres shortens the life span of living cells. It is a known fact that cells with shortened lifespan age earlier and predispose to many diseases, especially cancer types. The fact that old cells are the basis for many diseases and young cells are resistant to many diseases has revealed the reality of keeping the cells young in order to prevent diseases. Studies aimed at understanding the activation of the telomerase enzyme on telomeres, have shown that this enzyme will have a positive effect on cellular rejuvenation on living cells, prolong the life span of living cells, thus preventing age-related diseases before they occur, and also making it impossible for many types of cancer that may develop due to old age to occur in the first place. Predictions such as preventing and stopping cellular senescence in human cells, providing cellular rejuvenation by reversing cellular senescence and extending human life span as much as desired are also worthy of further emphasis with the studies carried out.

The application of quantitative telomerase activity measurement as an important indicator to monitor the cardiomyocyte differentiation process of human induced pluripotent stem cells under defined conditions

The construction of an in vitro differentiation system for human induced pluripotent stem cells (hiPSCs) has made exciting progress, but it is still of great significance to clarify the differentiation process. The use of conventional genetic and protein-labeled microscopes to observe or detect different stages of hiPSC differentiation is not specific enough and is cumbersome and time-consuming. In this study, in addition to analyzing the expression of gene/protein-related markers, we used a previously reported simple and excellent quantitative method of cellular telomerase activity based on a quartz crystal microbalance (TREAQ) device to monitor the dynamic changes in cellular telomerase activity in hiPSCs during myocardial differentiation under chemically defined conditions. Finally, by integrating these results, we analyzed the relationship between telomerase activity and the expression of marker genes/proteins as well as the cell type at each study time point. This dynamic quantitative measurement of cellular telomerase activity should be a promising indicator for monitoring dynamic changes in a stage of hiPSC differentiation and inducing cell types. This study provided a quantitative, dynamic and simple monitoring index for the in vitro differentiation process of hiPSC-CMs, which was a certain reference value for the optimization and improvement of the induction system.

The Evaluation of Telomere Length and Telomerase Activity Measurement in NF1 Tumors

The Evaluation of Telomere Length and Telomerase Activity Measurement in NF1 Tumors

P02.01.B The telomere maintenance mechanism spectrum and its dynamics in gliomas

Abstract The activation of the telomere maintenance mechanism (TMM) is one of the critical drivers of cancer cell immortality. In gliomas, TERT expression and TERT promoter mutation are considered to reliably indicate telomerase activation, while ATRX mutation indicates alternative lengthening of telomeres (ALT). However, these relationships have not been extensively validated in tumor tissues. Here, we show through the direct measurement of telomerase activity and ALT in a large set of glioma samples that the TMM in glioma cannot be defined in the dichotomy of telomerase activity and ALT, regardless of TERT expression, TERT promoter mutation and ATRX mutation. Moreover, we observed that a considerable proportion of gliomas lack both telomerase activity and ALT (Neither group). And this Neither group exhibited evidence of slow growth potential. From a set of longitudinal samples from a separate cohort of glioma patients, we discovered that the TMM is not fixed but changes with glioma progression. Collectively, these results suggest that the TMM is a dynamic entity and that reflects the plasticity of the oncogenic biological status of tumor cells and that the TMM should be defined by the direct measurement of telomerase enzyme activity and evidence of ALT.

TERT distal promoter GC islands are critical for telomerase and together with DNMT3B silencing may serve as a senescence-inducing agent in gliomas

Telomerase is reactivated in the majority of cancers. For instance, in gliomas, it is common that the TERT promoter is mutated. Research on telomere promoter GC islands have been focused primarily on proximal TERT promoter but little is known about the distal promoter. Therefore, in this study, we investigated the proximal and distal TERT promoter, in terms of DNA methylation. We did bisulfite sequencing in zebrafish tissue samples for the distal tert promoter. In the zebrafish brain tissues, we identified a hypomethylation site in the tert promoter, and found that this hypomethylation was associated with aging and shortened telomeres. Through site directed mutagenesis in glioma cell lines, we changed 10 GC spots individually, cloned into a reporter vector, and measured promoter activity. Finally, we silenced DNMT3B and measured telomerase activity along with vidaza and adriamycin treatments. Site directed mutagenesis of glioma cell lines revealed that each of the 10 GC spots are critical for telomerase activity. Changing GC to AT abolished promoter activity in all spots when transfected into glioma cell lines. Then, through silencing of DNMT3B, we observed a reduction in hTERT expression levels, while hTR remained the same, and a major increase in senescence-associated beta-galactosidase activity. Finally, we propose a model regarding the efficacy of two chemotherapeutic drugs, adriamycin and azacytidine, on gliomas. Here, we show that distal TERT promoter is critical; changing even one GC to AT abolishes TERT promoter activity. DNMT3B, a de novo methyltransferase, together with GC islands in distal TERT promoter plays an important role in regulation of telomerase expression and senescence.

The telomere maintenance mechanism spectrum and its dynamics in gliomas

BackgroundThe activation of the telomere maintenance mechanism (TMM) is one of the critical drivers of cancer cell immortality. In gliomas, TERT expression and TERT promoter mutation are considered to reliably indicate telomerase activation, while ATRX mutation and/or loss indicates an alternative lengthening of telomeres (ALT). However, these relationships have not been extensively validated in tumor tissues.MethodsTelomerase repeated amplification protocol (TRAP) and C-circle assays were used to profile and characterize the TMM cross-sectionally (n = 412) and temporally (n = 133) across glioma samples. WES, RNA-seq, and NanoString analyses were performed to identify and validate the genetic characteristics of the TMM groups.ResultsWe show through the direct measurement of telomerase activity and ALT in a large set of glioma samples that the TMM in glioma cannot be defined solely by the combination of telomerase activity and ALT, regardless of TERT expression, TERT promoter mutation, and ATRX loss. Moreover, we observed that a considerable proportion of gliomas lacked both telomerase activity and ALT. This telomerase activation-negative and ALT negative group exhibited evidence of slow growth potential. By analyzing a set of longitudinal samples from a separate cohort of glioma patients, we discovered that the TMM is not fixed and can change with glioma progression.ConclusionsThis study suggests that the TMM is dynamic and reflects the plasticity and oncogenicity of tumor cells. Direct measurement of telomerase enzyme activity and evidence of ALT should be considered when defining TMM. An accurate understanding of the TMM in glioma is expected to provide important information for establishing cancer management strategies.

Enzymatic DNA repair cascade-driven fluorophore encoding for sensitively sensing telomerase activity in cancer cells

Telomerase is an important reverse transcriptase that is in charge of maintaining telomeres length, and the dysregulation of telomerase activity is closely associated with cancers. Accurate measurement of telomerase activity is critical to clinical diagnosis and therapeutics. Herein, by taking advantage of in vivo repair mechanisms and single-molecule detection, we demonstrate the enzymatic DNA repair cascade-driven fluorophore encoding for sensitively sensing telomerase activity in cancer cells. The presence of telomerase enables repetitive addition of (TTAGGG)n to the 3′-OH end of telomerase substrate (TS) primer to generate long telomeric products. Telomeric product then hybridizes with the apurinic (AP) probe to induce the cleavage of AP site in dsDNA by APE1, yielding a ssDNA with a biotin and an OH group at 5′ and 3′ ends and simultaneously releasing the telomeric product which in turn hybridizes with new AP probes to yield numerous ssDNAs. By adding streptavidin-coated MBs, the ssDNAs are captured and subsequently functioned as primers to initiate template-free TdT-catalyzed random incorporation of dATPs and Cy5-dATPs into 3′-OH ends, producing long poly-A chains with multiple Cy5 molecules encoding and finally forming Cy5-ssDNA-MB complexes. After magnetic separation, Cy5-ssDNA-MBs are digested by Exo I, releasing large numbers of Cy5 molecules which can be measured by single-molecule detection. This strategy exhibits excellent specificity and high sensitivity with a limit of detection (LOD) of 1 cancer cell. Moreover, it can be employed to screen inhibitors and discriminate different cancer cell lines from normal cell lines, holding enormous potential in clinical diagnosis and therapeutics.

Telomeres and Age-Related Diseases.

Telomeres are at the non-coding ends of linear chromosomes. Through a complex 3-dimensional structure, they protect the coding DNA and ensure appropriate separation of chromosomes. Aging is characterized by a progressive shortening of telomeres, which compromises their structure and function. Because of their protective function for genomic DNA, telomeres appear to play an important role in the development and progression of many age-related diseases, such as cardiovascular disease (CVD), malignancies, dementia, and osteoporosis. Despite substantial evidence that links telomere length with these conditions, the nature of these observations remains insufficiently understood. Therefore, future studies should address the question of causality. Furthermore, analytical methods should be further improved with the aim to provide informative and comparable results. This review summarize the actual knowledge of telomere biology and the possible implications of telomere dysfunction for the development and progression of age-related diseases. Furthermore, we provide an overview of analytical techniques for the measurement of telomere length and telomerase activity.

SERS-based copper-mediated signal amplification strategy for simple and sensitive detection of telomerase activity

Simple and sensitive detection of telomerase activity is of vital importance for both early diagnosis and therapy of malignant tumors. Inspired by DNA-biobarcode amplification reported by Chad A. Mirkin, we developed a facile DNA-biobarcode-like SERS-based copper-mediated signal amplification strategy for sensitive detection of telomerase activity. In this strategy, a duplex DNA constructed by hybridization of a copper oxide nanoparticle (CuO NP)-labeled reporting sequence (RS) with the telomerase primer sequence (TS) is ingeniously designed, and anchored on the magnetic bead (MB) to build the CuO NPs-encoded magnetic bead (MB-CuO NPs) detection probe. Upon selective sensing of telomerase, telomerase elongation reaction and structure change of TS products make the CuO NP-RS displace and separate from MB. The separated CuO NPs are dissolved into a mass of Cu2+, which prompt monodisperse dopamine-functionalized AgNPs (D-AgNPs) signal probe into aggregation, resulting in color changes and significantly enhancing of SERS signal. The SERS signal increases with the increase of Cu2+, which is directly proportional to the telomerase. Benefiting from the transformation of CuO NP to Cu2+ with a high amplification effect, this strategy could realize the telomerase activity measurement down to 3 HeLa cells and a dynamic range of 10–10000 cells. It shows a significant improvement of sensitivity without need for other enzymes and elaborate design, which escapes from the complicated manipulations and design in polymerase chain reaction (PCR) and DNA amplification techniques. Moreover, with this strategy, telomerase activities of different cell lines and telomerase inhibitors screening were successfully performed. Significantly, it can also be utilized for visual detection of telomerase, which validates the potential on-site application and its application as point-of-care testing (POCT) for efficient monitoring. Given the high-performance for telomerase analysis, the strategy has a promising application in biological detection and clinical diagnosis, as well as point-of-care tests.

Targeting Telomere Biology in Acute Lymphoblastic Leukemia.

Increased cell proliferation is a hallmark of acute lymphoblastic leukemia (ALL), and genetic alterations driving clonal proliferation have been identified as prognostic factors. To evaluate replicative history and its potential prognostic value, we determined telomere length (TL) in lymphoblasts, B-, and T-lymphocytes, and measured telomerase activity (TA) in leukocytes of patients with ALL. In addition, we evaluated the potential to suppress the in vitro growth of B-ALL cells by the telomerase inhibitor imetelstat. We found a significantly lower TL in lymphoblasts (4.3 kb in pediatric and 2.3 kb in adult patients with ALL) compared to B- and T-lymphocytes (8.0 kb and 8.2 kb in pediatric, and 6.4 kb and 5.5 kb in adult patients with ALL). TA in leukocytes was 3.2 TA/C for pediatric and 0.7 TA/C for adult patients. Notably, patients with high-risk pediatric ALL had a significantly higher TA of 6.6 TA/C compared to non-high-risk patients with 2.2 TA/C. The inhibition of telomerase with imetelstat ex vivo led to significant dose-dependent apoptosis of B-ALL cells. These results suggest that TL reflects clonal expansion and indicate that elevated TA correlates with high-risk pediatric ALL. In addition, telomerase inhibition induces apoptosis of B-ALL cells cultured in vitro. TL and TA might complement established markers for the identification of patients with high-risk ALL. Moreover, TA seems to be an effective therapeutic target; hence, telomerase inhibitors, such as imetelstat, may augment standard ALL treatment.

THE POSITIVE EFFECT OF MOXONIDINE ON TELOMERASE ACTIVITY

Objective: To estimate the effect of moxonidine versus bisoprolol on cellular senescence processes in postmenopausal women with arterial hypertension (AH). Design and method: There was an open randomized control study. The study group was represented by 56 women with AH and a mean age of 63 ± 9.217 years, with SBP of 146.72 ± 7.127 mm Hg and DBP of 84.38 ± 7.941 mm Hg, who received moxonidine treatment (average dose 0.515 mg/day [0.4; 0.6]) for 12 months. The control group was comprised of 59 female patients with AH and a mean age of 61 ± 9.117 years, with SBP of 145.59 ± 6.102 mm Hg and DBP of 86.18 ± 6.682 mm Hg, who received treatment with bisoprolol (average dose 5.0 mg/day [5.0; 7.5]) for 12 months. For all patients, the measurement of telomerase activity was performed using genomic DNA real-time PCR at baseline and after 12 months of treatment. Statistical analysis was carried out using the SPSS/PASW Statistics software (version 18, SPSS Inc., Chicago, Illinois, USA). Results: In both groups there was a substantial and significant BP reduction, in the moxonidine treatment group: SBP – 126.93 ± 8.086 mm Hg (p < 0.001), DBP – 73.64 ± 7.522 mm Hg (p < 0.001); in the bisoprolol treatment group: SBP – 125.83 ± 8.097 mm Hg (p < 0.001), DBP – 73.31 ± 7.964 mm Hg (p < 0.001). Patients from the moxonidine treatment group demonstrated a significant reduction of body weight, on average, by 1.89% (from 75.7 ± 12.77 kg to 74.5 ± 11.7 kg,p < 0.001) and of BMI (from 29.359 ± 4.7 kg/m2 to 28.6 ± 4.4 kg/m2, p < 0.001). By contrast, in the bisoprolol treatment group patients’ average body weight increased by 2.22% (from 76.655 ± 13.754 kg to 78.13 ± 13.728 kg, p < 0.001) as well as BMI (from 29.037 ± 4.6 kg/m2 to 29.609 ± 4.7 kg/m2, p < 0.001). TA in the moxonidine treatment group increased from 0.87 [0.16; 1.18] to 1.1 [0.74; 1.5] (p < 0.001), and, conversely in the bisoprolol treatment group TA decreased from 1.1 [0.5; 1.6] to 0.94 [0.56; 1.5] (p < 0.001). Conclusions: The preliminary data suggests that moxonidine can be used as telomerase activator and effective geroprotective agent. Increased TA against the backdrop of moxonidine treatment may be explained by increased insulin sensitivity, decreased body weight, and, consequently, lower intensity of chronic inflammation.

Tetrahedral DNA Nanoconjugates for Simultaneous Measurement of Telomerase Activity and miRNA.

In this study, a tetrahedral DNA nanostructure was first self-assembled; this was then conjugated with gold nanoparticles (AuNPs) and carbon nanodots (CDs). The fabricated nanocomposites allow simultaneous analysis of telomerase activity and miRNA with dual fluorescence channels. By further introducing an iRGD peptide sequence, the nanoconjuates can be conveniently transferred inside living cells for in situ imaging. The analytical performances and anti-jamming capabilities are excellent. Meanwhile, the materials are highly biocompatible for intracellular applications. Therefore, the proposed biosystem shows great promise as a powerful tool for quantitative analysis of the dual biomarkers. The strategy can also be further exploited as a versatile platform for in situ detection of many other targets for early disease diagnosis.

Aging Process in Dermal Fibroblast Cell Culture of Green Turtle (Chelonia mydas)

Senescence in green turtle is an interesting process to study because until now no clear explanation has been established about senescence at cellular or molecular level in this species. One of common markers used for detecting senescence is telomere shortening. Reduced telomerase activity may also cause senescence. The aims of this research are to establish and identify dermal fibroblast cell culture from green turtle and also to compare telomere length and telomerase activity from the cells subculture 5 and 14. Cells were identified with Rabbit Anti-Vimentin Polyclonal Antibody and Goat Polyclonal Antibody using confocal microscope. Telomere length was obtained using TeloTAGGG Telomere Length Assay (Roche), while telomerase activity was obtained using TeloTAGGG Telomerase PCR ElisaPlus. Primary cell culture from green turtle skin showed fibroblastic morphology and immunocytochemistry results using vimentin antibody proved that the culture was fibroblast cell. Measurement of telomere length and telomerase activity showed that telomere length and telomerase activity of subculture 14 was greater than subculture 5. However, based on morphology, green turtle fibroblast skin cell culture showed senescent morphology. Therefore, possible aging mechanism that the green turtle fibroblast skin cell culture underwent did not go through both telomere shortening and reduced telomerase activity.

One-Step High-Throughput Telomerase Activity Measurement of Cell Populations, Single Cells, and Single-Enzyme Complexes.

Telomerase, a key enzyme involved in telomere homeostasis, is a major player involved in or required for sustained cell proliferation. It is expressed in ∼90% tumor but rarely in normal somatic cells. Therefore, telomerase serves as a diagnostic marker and therapeutic target of cancers. Although many methods are available for measuring telomerase activity, a convenient, fast, sensitive, and reliable method is still lacking for routine use in both clinics and research. Here, we present a single-enzyme sensitivity telomere repeat amplification protocol for quantifying telomerase activity. With multiple optimizations, the protocol pushes the ultimate detection limit down to a single telomerase complex, enabling measurement of telomerase activity of not only multiple cancerous/normal cell samples but also single cancer cells alone or even in the presence of 8000 normal cells. Implemented in a one-step mix-and-run format, the protocol offers a most sensitive, fast, accurate, and reproducible quantification of telomerase activity with linearity ranging from 20,000 HeLa cancer cells to a single telomerase complex. It requires minimal manual operation and experimental skill and is convenient for either low or high throughput of samples. We expect that the protocol should provide practical routine analyses of telomerase in both research and clinical applications. As an example, we demonstrate how telomerase activity evolves at the single-cell level and partitions in cell division in early mouse embryo development.

Telomerase as a Possible Candidate Targeting Therapy in Different Breast Cancer Cell Lines.

Background:Telomerase activity is up regulated in most breast cancer subtypes but not in the adjacent normal tissues. Thus, it is a promising target for anticancer therapy. The present work investigated the effects of telomerase inhibition by siRNA on breast cancer cell lines and studied the feasibility of whether the combined effect of doxorubicin with siRNA treatment on breast cancer cells potentiates a rapid cellular response to the cytotoxic effect of chemotherapy. Methods:This study was performed on Luminal A (MCF-7), triple negative (MDA-MB-468), and HER-2/neu (SKBR-3) human breast cancer cell lines, wherein telomerase activity inhibition by hTERT siRNA and doxorubicin was detected by measuring telomerase activity using Telomeric Repeat Amplification Protocol (TRAP assay), assessing cell viability through MTT assay, and evaluating apoptosis through scanning electron microscopy (SEM) and through estimating caspase-3 and -8 activities using enzyme-linked immunosorbent assay (ELISA). Results:In the present study, hTERT siRNA effectively reduced telomerase activity and cell viability to more than 90% and 60%, respectively, in most breast cancer cell lines within 72 hours after transfection. The combination of hTERT siRNA and doxorubicin showed a cumulative effect compared with either treatment alone (P < 0.05). Meanwhile, SEM demonstrated apoptotic morphologic cell changes. Conclusion:Telomerase inhibition is a promising strategy for the effective treatment of breast cancer. When used in combination with doxorubicin, it could potentiate the cytotoxic effect of the drug on breast cancer cells.

TERT and TERC mutations detected in cryptic dyskeratosis congenita suppress telomerase activity.

A cryptic form of dyskeratosis congenita (cDKC) has a gradual onset without the characteristic physical findings of DKC. cDKC is distinguished from other forms of bone marrow failure (BMF) through analysis of telomere shortening and gene mutations. Mutations in the telomerase reverse transcriptase (TERT) and telomere RNA component (TERC) genes have been detected in most Japanese cDKC patients. Therefore, we investigated the impact of each TERT and TERC mutation on telomerase activity. TERT and TERC mutants observed in DKC or cDKC patients were transfected into Saos-2 or VA13+TERT (TERT-expressing VA13 cells) cells to measure telomerase activity. Telomerase activity in cells expressing a mutant detected in cDKC patients was significantly lower (P<.0001) than in cells expressing the wild-type genes. In addition, some TERT mutations seen in cDKC (p.P632R, p.T726M) caused weaker (P=.0013) suppression of telomerase activity than others (p.G106W and p.G682D). In contrast, telomerase activity in cells expressing a TERT or TERC mutant detected in DKC patients did not significantly differ from cells expressing the wild-type genes. These findings suggest that TERT and TERC mutations detected in cDKC patients could potentially contribute to the pathogenesis of cDKC by blocking telomerase activity. However, TERT and TERC mutations detected in DKC patients did not affect telomerase activities, which means studying the telomerase activity of mutants are not always useful for the diagnosis of DKC.

A Multi-Type Collagen-Based Drink Supplement Significantly Improved Markers of Aging, both in vitro and in a Human Clinical Study

Introduction: Collagen is a ubiquitous structural protein found in skin, bone, muscle and connective tissue in humans and animals. Several studies have found significant positive impacts on skin health when collagen-containing dietary supplements are routinely ingested. A newly developed collagen product (4Life Transfer Factor Collagen (TF Collagen)) containing multiple types of collagen, transfer factors from colostrum, and other ingredients, was tested in vitro in a telomere model, and in vivo in a human skin health clinical study. Objective: The purpose of these studies was to determine if TF Collagen supplementation could significantly improve measures of aging and the overall skin health of the participants. Methods: The in vitro telomere study measured telomerase activity of lung tissue cells over 15 passages by optical density (OD). The telomerase activity was then compared between a control group and a TF Collagen-treated group at corresponding passages. For the human study, 26 subjects (aged 35-55) consumed one packet (eight grams) of TF Collagen daily for 84 days. Skin hydration, skin firmness, skin elasticity, and the appearance of fine lines and wrinkles were measured at day 42 and day 84. Results: The in vitro study found a significant increase in telomerase activity in cells treated with TF Collagen compared to the control. In the human clinical study, TF Collagen significantly improved skin hydration, skin firmness, and the appearance of fine lines and wrinkles, as well as subjective measures of skin health. Conclusion: A multi-type collagen supplement with other ingredients activated telomerase in vitro and significantly improved overall skin health in healthy men and women.

Telomerase activity in the differential diagnosis of pancreatic mass.

In this manuscript, we show that the detection of telomerase activity in pancreatic mass tissue provides early evidence of a cancerous process that requires a well-timed surgical treatment. Eighty-eight patients with pancreatic mass (both benign and malignant) were involved in the research. Comparative analyses of the data and instrumental methods to define the histological structure of tumor mass and measure telomerase activity have been carried out. Intense telomerase activity (+++) in the tissue of pancreatic mass determines cancer with high accuracy. One hundred percent of patients with pancreatic cancer had high telomerase activity. In 32.4% of patients with average telomerase activity (++) pancreatic cancer was diagnosed. The average telomerase activity (++) in pancreatic tumors gives an early indication of pancreatic cancer and requires dynamic observation for 6 to 12 months (P<0.05). Low telomerase activity (+) in patients with benign tumors is an accurate sign for confirming a diagnosis. The detection of telomerase activity in pancreatic mass tissue provides early evidence of a cancerous process that requires a well-timed surgical treatment.

Regulation of multiple energy transfer processes in a simple nano-system for sensitive telomerase detection

Telomerase, as a potential biomarker for early cancer diagnostics and therapies, has attracted considerable interests concerning its detection and monitoring. Herein, we develop a novel method for sensitive detection of telomerase activity by designing a gold nanoparticles/graphene oxide (AuNPs/GO) probe. The AuNPs were functionalized with a telomerase substrate (TS) primer and a 6-carboxy-fluorescein (FAM)-modified complementary DNA (P1). In the absence of telomerase, P1 exists in the random-coiled conformation, and the fluorescence resonance energy transfer (FRET) from FAM to AuNPs and GO results in efficient fluorescence quenching. In the presence of telomerase, the multiple hybridization between TS extension products and P1 leads to the conformation transition of P1 from single-stranded DNA to double-stranded rigid structure, and thus the FRET process can be prevented with the efficient fluorescence recovery. The metal enhanced fluorescence (MEF) effect between FAM and AuNPs can further effectively enhance the fluorescence of FAM, and thus the sensitivity and specificity of telomerase detection can be remarkably improved. It is worth mentioning that the proposed strategy does not need to design complex hairpin structure and allows the measurement of telomerase activity in three crude cell extracts equivalent to 7 HeLa cells, 8 A549 cells and 8 L929 cells in 1 h. In addition, the present sensing platform can be applied to inhibitor screening, in situ telomerase imaging, and intracellular drug delivery.