Telomerase therapeutics for cancer: challenges and new directions

Canonical and non-canonical functions of the non-coding RNA component (TERC) of telomerase complex

The telomerase complex consists of a protein component (TERT), which has reverse transcriptase activity, and an RNA component (TERC), which serves as a template for telomere synthesis. Evidence is rapidly accumulating regarding the non-canonical functions of these components in both normal or diseased cells. An oligonucleotide-based drug, the first telomerase inhibitor, secured FDA approval in June 2024. We recently summarized the non-canonical functions of TERT in viral infections and cancer. In this review, we expand on these non-canonical functions of TERC beyond telomere maintenance. Specifically, we explore TERC's roles in cellular aging and senescence, immune regulation, genetic diseases, human cancer, as well as involvement in viral infections and host interactions. Finally, we discuss a transcription product of telomere repeats, TERRA, and explore strategies for targeting TERC as a therapeutic approach.

Gold nanoparticle-mediated fluorescence resonance energy transfer for analytical applications in the fields of life health and safety

Fluorescence Resonance Energy Transfer (FRET) has emerged as a predominant, highly sensitive, and homogeneous optical analytical technique in the realm of analytical testing and bio-imaging. Gold nanoparticles (AuNPs) demonstrate a size-dependent, broader absorption range within visible wavelengths owing to the phenomenon of surface plasmon resonance. As a result, they can effectively act as light acceptors, enabling the creation of a donor-acceptor system crucial for achieving precise target analyte analysis. In this comprehensive review, we present an extensive survey of recent research advancements in the field of FRET techniques based on AuNPs for the analytical detection of a wide range of entities, including some biomolecules, pesticides, enzymes, microorganisms, food safety and environmental pollutants. Additionally, we elucidate the procedural strategies and underlying mechanisms involved. Finally, we provide perspectives on the current issues and future efforts surrounding the FRET applications of AuNPs in biological analysis. Overall, this review aims to provide a holistic comprehension of gold nanoparticle applications in life analysis using FRET, while also presenting a promising vision for future endeavors in this domain.

Association of hTERT MNS16A polymorphism with clinical outcomes of North Indian lung cancer patients undergoing platinum-based doublet chemotherapy

BACKGROUND

Telomerase has been linked to aging and cancer. The MNS16A polymorphism in the hTERT gene plays a significant role in modulating telomerase activity and highlights the complexity of telomere-related genetics in cancer research.

EXPERIMENTAL DESIGN

We genotyped 401 lung-cancer samples treated with platinum-based chemotherapy to identify the MNS16A polymorphism. We assessed overall survival using the Kaplan-Meier method and Cox regression analysis for adjusted hazard ratios. Stratified analyses evaluated risks for subgroups based on clinicopathologic parameters, outcomes, and toxicity calculated.

RESULTS

Our findings show no significant link between MNS16A polymorphism and lung-cancer survival. However, in squamous cell carcinoma (SQCC) patients, the SS genotype was associated with poorer survival (p = 0.004). Patients with LS + SS genotypes responded better to gemcitabine in univariate (p = 0.003) and multivariate analyses (p = 0.014). The LS genotype was linked to a lower risk of progression to stage 4 (p = 0.011) and metastasis (p = 0.015) but an increased risk of T4 tumor size (p = 0.026). No significant correlations were found between MNS16A polymorphism and treatment-related toxicities.

CONCLUSION

The MNS16A polymorphism does not significantly impact overall lung-cancer survival but affects specific subgroups, influencing certain lung-cancer subtypes and treatment responses while having limited predictive value for overall outcomes or toxicity risks.

The impact of Radioresistant-Related Telomere Genes in the prognosis and immune infiltration in lung adenocarcinoma

INTRODUCTION

Lung adenocarcinoma (LUAD), a common subtype of NSCLC, has a high mortality rate. Telomere genes are influenced by radiation therapy, affecting treatment response. Additionally, immune cell presence in the tumor microenvironment plays a crucial role in cancer prognosis. However, the role of Radioresistant-Related Telomere Genes (RRTGs) in LUAD prognosis and immune infiltration remains unclear.

METHODS

In this research, we utilized diverse bioinformatics techniques to examine our personally tested information along with publicly accessible datasets. We conducted a comprehensive study on the genetic and transcriptional differences, predictive significance, and expression profiles of RRTGs. Afterwards, a RRTGs score was developed to forecast the overall survival (OS) and ascertain its reliable predictive capacity for patients with LUAD. Following this, dependable nomograms were developed to enhance the practicality of RRTGs scoring in a clinical setting. Furthermore, the investigation delved into the associations among RRTGs, infiltration of immune cells, prognosis, and clinical treatments of patients. Gene Set Enrichment Analysis (GSEA) was conducted to explore the potential mechanisms by which RRTGs influence the regulation of LUAD. Then, Western blot, qRT-PCR and Immunohistochemistry were used to detect the expression levels of RRTGs in cell lines and LUAD tumor tissues.

RESULTS

Our research indicates that certain genes related to telomeres have a notable correlation with the prognosis of patients diagnosed with LUAD. The RRTGs score, which includes three key genes (ARRB1, PLK1, and DSG2), was developed to forecast the OS and its dependable predictive capability for individuals diagnosed with LUAD was ascertained. Afterwards, extremely reliable nomograms were developed to improve the practicality of the RRTGs score. Moreover, as illustrated, genetic characteristics can be utilized to assess the infiltration of immune cells in tumors, as well as clinical attributes and prognosis. RRTGs score characterizes tumor mutational burden, immune activity, and notable survival probabilities in addition. Furthermore, GSEA results revealed that RRTGs may influence LUAD by modulating immune-related pathways in high-risk groups and regulating cell cycle and DNA repair processes in low-risk groups. The RRTGs (ARRB1 and PLK1) were upregulated in A549 cells and radiosensitive NSCLC tissues compared to radioresistant A549 cells and NSCLC tissues.

CONCLUSION

In conclusion, this research emphasizes the significance of RRTGs in the outlook of LUAD. The findings contributed to a better understanding of the link between radiotherapy, telomere-related genes, and prognosis in LUAD, and identified potential therapeutic targets for patients with LUAD.

Endogenous Telomerase-Activated Fluorescent Probes for Specific Detection and Imaging of Flap Endonuclease 1 in Cancer Cells and Tissues

Flap endonuclease 1 (FEN1) is a structure-specific DNA repair enzyme that has emerged as a potential target for cancer diagnosis and treatment. However, existing FEN1 assays often suffer from complicated reaction schemes and laborious procedures, and only a few methods are available for the detection and imaging of FEN1 in living cells. Especially, FEN1 is not exclusive to cancer cells, but it is also shared by normal cells. Consequently, the specific detection of FEN1 in cancer cells remains a challenge. Herein, we develop a simple and selective fluorescent biosensor for the specific imaging of FEN1 in cancer cells and tissues by engineering a FEN1 detection probe with a telomerase-responsive unit. In the presence of telomerase, it induces an extension reaction and subsequent intramolecular reconfiguration of the detection probe, generating a suitable branched DNA structure for FEN1 recognition and facilitating the cleavage of the flap by FEN1 for the recovery of fluorescence signal. Because telomerase is undetectable in normal cells but highly upregulated in cancer cells, the detection probe can only be activated in cancer cells to generate a high signal. This assay is quite simple, with the requirement of merely a single probe for dual enzyme recognition and signal output. With the integration of the single-molecule counting technology, this biosensor can achieve a detection limit of 1.2 × 10-5 U/μL, and it can accurately detect FEN1 in living cells and clinical tissues, providing a new avenue for FEN1-associated fundamental research and clinical diagnosis.

Pyroptosis in lung cancer: The emerging role of non-coding RNAs

Lung cancer remains an intractable malignancy worldwide, prompting novel therapeutic modalities. Pyroptosis, a lethal form of programmed cell death featured by inflammation, has been involved in cancer progression and treatment response. Simultaneously, non-coding RNA has been shown to have important roles in coordinating pattern formation and oncogenic pathways, including long non-coding RNA (lncRNAs), microRNA (miRNAs), circular RNA (circRNAs), and small interfering RNA (siRNAs). Recent studies have revealed that ncRNAs can promote or inhibit pyroptosis by interacting with key molecular players such as NLRP3, GSDMD, and various transcription factors. This dual role of ncRNAs offers a unique therapeutic potential to manipulate pyroptosis pathways, providing opportunities for innovative cancer treatments. In this review, we integrate current research findings to propose novel strategies for leveraging ncRNA-mediated pyroptosis as a therapeutic intervention in lung cancer. We explore the potential of ncRNAs as biomarkers for predicting patient response to treatment and as targets for overcoming resistance to conventional therapies.

Role of renin angiotensin system inhibitors and metformin in Glioblastoma Therapy: a review

Glioblastoma multiforme (GBM) is a highly aggressive and incurable disease accounting for about 10,000 deaths in the USA each year. Despite the current treatment approach which includes surgery with chemotherapy and radiation therapy, there remains a high prevalence of recurrence. Notable improvements have been observed in persons receiving concurrent antihypertensive drugs such as renin angiotensin inhibitors (RAS) or the antidiabetic drug metformin with standard therapy. Anti-tumoral effects of RAS inhibitors and metformin have been observed in in vitro and in vivo studies. Although clinical trials have shown mixed results, the potential for the use of RAS inhibitors and metformin as adjuvant GBM therapy remains promising. Nevertheless, evidence suggest that these drugs exert multimodal antitumor actions; by particularly targeting several cancer hallmarks. In this review, we highlight the results of clinical studies using multidrug cocktails containing RAS inhibitors and or metformin added to standard therapy for GBM. In addition, we highlight the possible molecular mechanisms by which these repurposed drugs with an excellent safety profile might elicit their anti-tumoral effects. RAS inhibition elicits anti-inflammatory, anti-angiogenic, and immune sensitivity effects in GBM. However, metformin promotes anti-migratory, anti-proliferative and pro-apoptotic effects mainly through the activation of AMP-activated protein kinase. Also, we discussed metformin's potential in targeting both GBM cells as well as GBM associated-stem cells. Finally, we summarize a few drug interactions that may cause an additive or antagonistic effect that may lead to adverse effects and influence treatment outcome.

Construction of single-molecule counting-based biosensors for DNA-modifying enzymes: A review

DNA-modifying enzymes act as critical regulators in a wide range of genetic functions (e.g., DNA damage & repair, DNA replication), and their aberrant expression may interfere with regular genetic functions and induce various malignant diseases including cancers. DNA-modifying enzymes have emerged as the potential biomarkers in early diagnosis of diseases and new therapeutic targets in genomic research. Consequently, the development of highly specific and sensitive biosensors for the detection of DNA-modifying enzymes is of great importance for basic biomedical research, disease diagnosis, and drug discovery. Single-molecule fluorescence detection has been widely implemented in the field of molecular diagnosis due to its simplicity, high sensitivity, visualization capability, and low sample consumption. In this paper, we summarize the recent advances in single-molecule counting-based biosensors for DNA-modifying enzyme (i.e, alkaline phosphatase, DNA methyltransferase, DNA glycosylase, flap endonuclease 1, and telomerase) assays in the past four years (2019 - 2023). We highlight the principles and applications of these biosensors, and give new insight into the future challenges and perspectives in the development of single-molecule counting-based biosensors.

Terahertz Photons Inhibit Cancer Cells Long Term by Suppressing Nano Telomerase Activity

Telomeres are nanoscale DNA-protein complexes to protect and stabilize chromosomes. The reexpression of telomerase in cancer cells is a key determinant crucial for the infinite proliferation and long-term survival of most cancer cells. However, the use of telomerase inhibitors for cancer treatment may cause problems such as poor specificity, drug resistance, and cytotoxicity. Here, we discovered a nondrug and noninvasive terahertz modulation strategy capable of the long-term suppression of cancer cells by inhibiting telomerase activity. First, we found that an optimized frequency of 33 THz photon irradiation effectively inhibited the telomerase activity by molecular dynamics simulation and frequency filtering experiments. Moreover, in vitro experiments showed that telomerase activity in 4T1 and MCF-7 cells significantly decreased by 77% and 80% respectively, after 21 days of regular 33 THz irradiation. Furthermore, two kinds of cells were found to undergo aging, apoptosis, and DNA double-strand breaks caused by telomere crisis, which seriously affected the survival of cancer cells. In addition, the tumorigenicity of 4T1 cells irradiated with 33 THz waves for 21 days in in vivo mice decreased by 70%. In summary, this study demonstrates the potential application of THz modulation in nano therapy for cancer.

2.7 Å cryo-EM structure of human telomerase H/ACA ribonucleoprotein

Telomerase is a ribonucleoprotein (RNP) enzyme that extends telomeric repeats at eukaryotic chromosome ends to counterbalance telomere loss caused by incomplete genome replication. Human telomerase is comprised of two distinct functional lobes tethered by telomerase RNA (hTR): a catalytic core, responsible for DNA extension; and a Hinge and ACA (H/ACA) box RNP, responsible for telomerase biogenesis. H/ACA RNPs also have a general role in pseudouridylation of spliceosomal and ribosomal RNAs, which is critical for the biogenesis of the spliceosome and ribosome. Much of our structural understanding of eukaryotic H/ACA RNPs comes from structures of the human telomerase H/ACA RNP. Here we report a 2.7 Å cryo-electron microscopy structure of the telomerase H/ACA RNP. The significant improvement in resolution over previous 3.3 Å to 8.2 Å structures allows us to uncover new molecular interactions within the H/ACA RNP. Many disease mutations are mapped to these interaction sites. The structure also reveals unprecedented insights into a region critical for pseudouridylation in canonical H/ACA RNPs. Together, our work advances understanding of telomerase-related disease mutations and the mechanism of pseudouridylation by eukaryotic H/ACA RNPs.

Retrospective Analysis of the Clinical Characteristics of Patients with Breast Cancer Treated with Telomerase Peptide Immunotherapy Combined with Cytotoxic Chemotherapy

Purpose

Telomerase activation, a critical step in cancer progression, occurs in approximately 95% of breast cancer cases. Telomerase is an attractive therapeutic target for breast cancer owing to its unique expression pattern. GV1001, a telomerase-derived peptide, is loaded onto human leukocyte antigen (HLA) class II antigen-presenting cells and binds to CD4+ T cell activating immune responses. This study aimed to evaluate the effectiveness and safety of co-administration of GV1001 and cytotoxic chemotherapy in patients with heavily-treated metastatic breast cancer.

Patients and methods

We analyzed 63 patients with breast cancer who received both GV1001 and cytotoxic chemotherapy. The GV 1001 administration methods involves 0.56 mg intradermal injection three times during the first week, one time at weeks 2, 3, 4, and 6, and then once every 28 days. The primary endpoint of this study was quality of life according to EORTC QLO-C30 and EQ-5D, while the secondary endpoint was the antitumor response according to RECIST 1.1, progression-free survival, overall survival, and toxicity profile.

Results

In 34 patients with HR+ breast cancer evaluable for tumor response, the disease control rate (DCR) and overall response rate (ORR) were 58.8% and 26.4%, respectively. The DCR and ORR were 66.6% and 28.5% in 21 patients with HER-2+ and 50% and 25% in patients with triple-negative breast cancer (TNBC), respectively. The median progression free survival was 10.4, 8.7, and 5.6 months in HR+, HER-2+, TNBC, respectively. The overall survival was 19.7, 13.2, and 9.4 months for patients with HR+, HER-2+, and TNBC, respectively. Most patients had an improved quality of life with statistically significant differences in some variables. The patients in this study experienced no additional toxicities other than the cytotoxic chemotherapy-associated side effects.

Conclusion

GV1001 is a relatively safe anticancer vaccine for patients with heavily-treated breast cancer and can to improve the quality of life.

Countercurrent chromatography separation of vitamin E isomers in a co-current mode

Vitamin E represents a group of lipophilic phenolic compounds, including α-tocopherol, β-tocopherol, γ-tocopherol, and δ-tocopherol, and α-tocotrienol, β-tocotrienol, γ-tocotrienol, and δ-tocotrienol isomers. Different forms of vitamin E have been proven to exhibit varying biological activities. However, due to their structural similarities, the separation of vitamin E isomers is a challenging task. Therefore, it is crucial to establish an efficient method for isolating individual isomers. In this study, co-current countercurrent chromatography was employed to isolate vitamin E isomers from commercial capsules using a n-heptane-methanol-water (10:9.5:0.5, v/v) solvent system. The partition coefficients of the main constituents in the capsules ranged from 0.94 to 6.23, requiring over 450 min for a complete separation. To improve separation efficiency, a co-current elution mode was implemented and the flow rates of the two liquid phases as well as sample amount were examined. The results suggested that increasing the flow rate of the stationary phase and sample size could result in more effective separation, shorter separation time, and higher yield. It proved that co-current countercurrent chromatography was an effective method for the separation of vitamin E isomers.

Amplification-free detection of telomerase activity at the single-cell level via Cas12a-lighting-up single microbeads (Cas12a-LSMBs)

Telomerase overexpresses in almost all cancer cells and has been deemed a universal biomarker for cancer diagnosis and therapy. However, simple and ultrasensitive detection of telomerase activity in single-cells is still a huge challenge. Herein, we wish to report Cas12a-lighting up single microbeads (Cas12a-LSMBs) for ultrasensitive detection of telomerase activity without nucleic acid amplification. In this platform, single-strand DNA reporter (ssDNA reporter)-functionalized single-microbeads (functionalized-SMBs) are employed as a reactor for the trans-cleavage of telomerase-activated CRISPR/Cas12a as well as a reporting unit for fluorescence signal enrichment and visualization. Due to the space-confined effect and signal enrichment mechanism on the surface of the functionalized SMBs, the Cas12a-LSMBs can accurately detect telomerase activity in crude cell lysates with high specificity. Importantly, we have demonstrated that the Cas12a-LSMBs are a reliable and practical tool to detect telomerase activity in single cells and investigate cellular heterogeneity of telomerase activity from cell-to-cell variations.

Telomere biology: from disorders to hematological diseases

Variations in the length of telomeres and pathogenic variants involved in telomere length maintenance have been correlated with several human diseases. Recent breakthroughs in telomere biology knowledge have contributed to the identification of illnesses named "telomeropathies" and revealed an association between telomere length and disease outcome. This review emphasizes the biology and physiology aspects of telomeres and describes prototype diseases in which telomeres are implicated in their pathophysiology. We also provide information on the role of telomeres in hematological diseases ranging from bone marrow failure syndromes to acute and chronic leukemias.

Telomere Targeting Chimera Enables Targeted Destruction of Telomeric Repeat-Binding Factor Proteins

Telomeres are naturally shortened after each round of cell division in noncancerous normal cells, while the activation of telomerase activity to extend telomere in the cancer cell is essential for cell transformation. Therefore, telomeres are regarded as a potential anticancer target. In this study, we report the development of a nucleotide-based proteolysis-targeting chimera (PROTAC) designed to degrade TRF1/2 (telomeric repeat-binding factor 1/2), which are the key components of the shelterin complex (telosome) that regulates the telomere length by directly interacting with telomere DNA repeats. The prototype telomere-targeting chimeras (TeloTACs) efficiently degrade TRF1/2 in a VHL- and proteosome-dependent manner, resulting in the shortening of telomeres and suppressed cancer cell proliferation. Compared to the traditional receptor-based off-target therapy, TeloTACs have potential application in a broad spectrum of cancer cell lines due to their ability to selectively kill cancer cells that overexpress TRF1/2. In summary, TeloTACs provide a nucleotide-based degradation approach for shortening the telomere and inhibiting tumor cell growth, representing a promising avenue for cancer treatment.

Angelica sinensis extract induces telomere dysfunction, cell cycle arrest, and mitochondria-mediated apoptosis in human glioblastoma cells

Glioblastoma (GB) is one of the most aggressive and malignant tumors of the central nervous system. Conventional treatment for GB requires surgical resection followed by radiotherapy combined with temozolomide chemotherapy; however, the median survival time is only 12-15 months. Angelica sinensis Radix (AS) is commonly used as a traditional medicinal herb or a food/dietary supplement in Asia, Europe, and North America. This study aimed to investigate the effect of AS-acetone extract (AS-A) on the progression of GB and the potential mechanisms underlying its effects. The results indicated that AS-A used in this study showed potency in growth inhibition of GB cells and reduction of telomerase activity. In addition, AS-A blocked the cell cycle at the G₀/G₁ phase by regulating the expression of p53 and p16. Furthermore, apoptotic morphology, such as chromatin condensation, DNA fragmentation, and apoptotic bodies, was observed in AS-A-treated cells, induced by the activation of the mitochondria-mediated pathway. In an animal study, AS-A reduced tumor volume and prolonged lifespans of mice, with no significant changes in body weight or obvious organ toxicity. This study confirmed the anticancer effects of AS-A by inhibiting cell proliferation, reducing telomerase activity, altering cell cycle progression, and inducing apoptosis. These findings suggest that AS-A has great potential for development as a novel agent or dietary supplement against GB.

Hyperpolarized δ-[1- 13C]gluconolactone imaging visualizes response to TERT or GABPB1 targeting therapy for glioblastoma

TERT promoter mutations are a hallmark of glioblastoma (GBM). Accordingly, TERT and GABPB1, a subunit of the upstream mutant TERT promoter transcription factor GABP, are being considered as promising therapeutic targets in GBM. We recently reported that the expression of TERT or GABP1 modulates flux via the pentose phosphate pathway (PPP). Here, we investigated whether 13C magnetic resonance spectroscopy (MRS) of hyperpolarized (HP) δ- [1-13C]gluconolactone can serve to image the reduction in PPP flux following TERT or GABPB1 silencing. We investigated two different human GBM cell lines stably expressing shRNAs targeting TERT or GABPB1, as well as doxycycline-inducible shTERT or shGABPB1cells. MRS studies were performed on live cells and in vivo tumors, and dynamic sets of 13C MR spectra were acquired following injection of HP δ-[1-13C]gluconolactone. HP 6-phosphogluconolactone (6PG), the product of δ-[1-13C]gluconolactone via the PPP, was significantly reduced in TERT or GABPB1-silenced cells or tumors compared to controls in all our models. Furthermore, a positive correlation between TERT expression and 6PG levels was observed. Our data indicate that HP δ-[1-13C]gluconolactone, an imaging tool with translational potential, could serve to monitor TERT expression and its silencing with therapies that target either TERT or GABPB1 in mutant TERT promoter GBM patients.

Discovering potential stabilizers for KRAS22RT G-quadruplex DNA: an alternative next generation approach to treat pancreatic cancer

KRAS is the signature gene responsible for the occurrence of pancreatic cancer, which is a complex, multifactorial and intractable lethal malignancy. Prevention and treatment of the ailment have always been a key motivation behind the search for new therapeutic drug molecules. G-quadruplexes are non-canonical guanine-rich secondary structures, commonly formed at eukaryotic telomeric ends, oncogenic promotors and G-rich regions of the DNA. These G-quadruplexes play a crucial role in the regulation of gene expression and maintenance of genome integrity, therefore, they are considered as emerging potential therapeutic drug targets. The present study is concerned with the discovery of a potential stabilizer for KRAS22RT G-quadruplex DNA, located in the NHE region of the promotor, while inhibiting the upregulation of KRAS proto-oncogene, as an alternative approach for the treatment of pancreatic cancer. Various chemical libraries have been virtually screened against the targeted G4 structure and 143 compounds showed promising results. However, molecular dynamic studies, ADME and toxicity analyses predicted that three compounds belonging to the class of tetra-substituted phenanthrolines (i.e., 7i, 7j and 7k) can not only effectively stabilize KRAS22RT G4 structure but also have least toxic effects in the in vivo system. Therefore, it is highly recommended to further investigate their effectiveness and efficacy through experimental analysis in laboratory.Communicated by Ramaswamy H. Sarma.

Proximity ligation-transcription circuit-powered exponential amplifications for single-molecule monitoring of telomerase in human cells

We develop a new strategy for single-molecule monitoring of telomerase based on proximity ligation-transcription circuit-powered exponential amplifications. This strategy exhibits high sensitivity with a detection limit of 0.1 aM for the synthetic telomerase product TPC4 in vitro and 1 HeLa cell in vivo. Moreover, it can screen potential inhibitors, discriminate telomerase from interferents, and distinguish cancer cells from normal cells.

Designing a multitarget In(III) compound to overcome the resistance of lung cancer cells to cisplatin

Designing novel anticancer non-platinum metal agents is fully challenging. Herein, a series of little-known indium (In) 2-acetylpyridine thiosemicarbazone compounds as potential anticancer agents were designed, synthesized, and characterized. The hydrogen atoms at the N-4 position with the alkyl of the In compounds significantly increased cellular uptake and cytotoxicity. In(III) compounds showed significantly higher cytotoxicity toward cisplatin-resistant cell lines than cisplatin. More importantly, C4 greatly inhibited A549DDP tumor growth in a vaccinated mouse model. C4 exerted cytotoxic effects via a multitarget mechanism. First, it activated p53 and blocked the cell cycle at the S phase, which then led to weak expression levels of cyclin and related kinases and upregulation of the expression levels of cyclin-dependent kinase inhibitors. C4 also depolarized the mitochondrial membrane potential and regulated the expression of the Bcl-2 family, which then released cyt-c and activated caspase-3/8/9 to execute apoptotic pathways. Then, it inhibited telomerase through the inhibition of the expression of the c-Myc regulator gene and expression of the human telomerase reverse transcriptase. Furthermore, C4 showed excellent antimetastatic activity.

Ageing, Metabolic Dysfunction, and the Therapeutic Role of Antioxidants

The gradual ageing of the world population has been accompanied by a dramatic increase in the prevalence of obesity and metabolic diseases, especially type 2 diabetes. The adipose tissue dysfunction associated with ageing and obesity shares many common physiological features, including increased oxidative stress and inflammation. Understanding the mechanisms responsible for adipose tissue dysfunction in obesity may help elucidate the processes that contribute to the metabolic disturbances that occur with ageing. This, in turn, may help identify therapeutic targets for the treatment of obesity and age-related metabolic disorders. Because oxidative stress plays a critical role in these pathological processes, antioxidant dietary interventions could be of therapeutic value for the prevention and/or treatment of age-related diseases and obesity and their complications. In this chapter, we review the molecular and cellular mechanisms by which obesity predisposes individuals to accelerated ageing. Additionally, we critically review the potential of antioxidant dietary interventions to counteract obesity and ageing.

Entropy-Driven Self-Assembly of Single Quantum Dot Sensor for Catalytic Imaging of Telomerase in Living Cells

Telomerase is a highly valuable cancer diagnosis biomarker and a promising cancer therapy target. So far, most telomerase assays are limited by the involvement of tedious procedures, multiple enzymes, and complicated reaction schemes. Sensitive monitoring of low-abundant telomerase in living cells remains a challenge. Herein, we demonstrate an entropy-driven catalytic assembly of quantum dot (QD) sensors for accurate detection and imaging of telomerase activity in living cells. In this sensor, target telomerase specifically catalyzes extension of telomerase primer, and the extended primer subsequently acts as a catalyst to continuously initiate entropy-driven catalytic reaction, generating a large number of fluorophore- and biotin-labeled DNAs that can be self-assembled on the QD surface to induce an efficient Föster resonance energy transfer signal. The proposed sensor requires a single step for both recognition and amplification of the telomerase signal, eliminating the use of either protein enzymes or laborious procedures. Taking advantage of the inherent superiority of single-molecule fluorescence detection and high amplification efficiency of the entropy-driven reaction, this sensor demonstrates single-cell sensitivity for the in vitro assay. Moreover, it is capable of screening the telomerase inhibitor, discriminating different tumor cells from normal ones, and even real-time imaging telomerase in living cells, providing a novel platform for telomerase-associated cancer diagnosis and drug screening.

Insights into the Small Molecule Targeting of Biologically Relevant G-Quadruplexes: An Overview of NMR and Crystal Structures

G-quadruplexes turned out to be important targets for the development of novel targeted anticancer/antiviral therapies. More than 3000 G-quadruplex small-molecule ligands have been described, with most of them exerting anticancer/antiviral activity by inducing telomeric damage and/or altering oncogene or viral gene expression in cancer cells and viruses, respectively. For some ligands, in-depth NMR and/or crystallographic studies were performed, providing detailed knowledge on their interactions with diverse G-quadruplex targets. Here, the PDB-deposited NMR and crystal structures of the complexes between telomeric, oncogenic or viral G-quadruplexes and small-molecule ligands, of both organic and metal-organic nature, have been summarized and described based on the G-quadruplex target, from telomeric DNA and RNA G-quadruplexes to DNA oncogenic G-quadruplexes, and finally to RNA viral G-quadruplexes. An overview of the structural details of these complexes is here provided to guide the design of novel ligands targeting more efficiently and selectively cancer- and virus-related G-quadruplex structures.

DNA-Based Nanoprobes for Simultaneous Detection of Telomerase and Correlated Biomolecules

Telomerase (TE), a ribonucleoprotein reverse transcriptase, is enzymatically activated in most tumor cells and is responsible for promoting tumor progression and malignancy by enabling replicative immortality of cancer cells. TE has become an important hallmark for cancer diagnosis and a potential therapy target. Therefore, accurate and in site detection of TE activity, especially the simultaneous imaging of TE activity and its correlated biomolecules, is highly essential to medical diagnostics and therapeutics. DNA-based nanoprobes, with their effective cell penetration capability and programmability, are the most advantageous for detection of intracellular TE activity. This concept article introduces the recent strategies for in situ sensing and imaging of TE activity, with a focus on simultaneous detection of TE and related biomolecules, and provides challenges and perspectives for the development of new strategies for such correlated imaging.

Positron emission tomography molecular imaging-based cancer phenotyping

During the past several decades, numerous studies have provided insights into biological characteristics of cancer cells and identified various hallmarks of cancer acquired in the tumorigenic processes. However, it is still challenging to image these distinctive traits of cancer to facilitate the management of patients in clinical settings. The rapidly evolving field of positron emission tomography (PET) imaging has provided opportunities to investigate cancer's biological characteristics in vivo. This article reviews the current status of PET imaging on characterizing hallmarks of cancer and discusses the future directions of PET imaging strategies facilitating in vivo cancer phenotyping.

Insights into POT1 structural dynamics revealed by cryo-EM

Telomeres are protein-DNA complexes that protect the ends of linear eukaryotic chromosomes. Mammalian telomeric DNA consists of 5′-(TTAGGG)n-3′ double-stranded repeats, followed by up to several hundred bases of a 3′ single-stranded G-rich overhang. The G-rich overhang is bound by the shelterin component POT1 which interacts with TPP1, the component involved in telomerase recruitment. A previously published crystal structure of the POT1 N-terminal half bound to the high affinity telomeric ligand 5′-TTAGGGTTAG-3′ showed that the first six nucleotides, TTAGGG, are bound by the OB1 fold, while the adjacent OB2 binds the last four, TTAG. Here, we report two cryo-EM structures of full-length POT1 bound by the POT1-binding domain of TPP1. The structures differ in the relative orientation of the POT1 OB1 and OB2, suggesting that these two DNA-binding OB folds take up alternative conformations. Supporting DNA binding studies using telomeric ligands in which the OB1 and OB2 binding sites were spaced apart, show that POT1 binds with similar affinities to spaced or contiguous binding sites, suggesting plasticity in DNA binding and a role for the alternative conformations observed. A likely explanation is that the structural flexibility of POT1 enhances binding to the tandemly arranged telomeric repeats and hence increases telomere protection.

Neuroblastoma-Telomere maintenance, deregulated signaling transduction and beyond

The childhood malignancy neuroblastoma belongs to the group of embryonal tumors and originates from progenitor cells of the sympathoadrenal lineage. Treatment options for children with high-risk and relapsed disease are still very limited. In recent years, an ever-growing molecular diversity was identified using (epi)-genetic profiling of neuroblastoma tumors, indicating that molecularly targeted therapies could be a promising therapeutic option. In this review article, we summarize the various molecular subtypes and genetic events associated with neuroblastoma and describe recent advances in targeted therapies. We lay a strong emphasis on the importance of telomere maintenance mechanisms for understanding tumor progression and risk classification of neuroblastoma.

Expression of telomerase reverse transcriptase in peripheral T-cell lymphoma

Telomere length is maintained by the activation of telomerase, which causes continuous cell division and proliferation in many carcinomas. A catalytic reverse transcriptase protein (TERT) encoded by the TERT gene plays a critical role in the activation of telomerase. We performed a molecular and pathological analysis of the TERT against three different peripheral T‐cell lymphoma (PTCL) subtypes: PTCL, not otherwise specified (PTCL‐NOS), angioimmunoblastic T‐cell lymphoma (AITL), and adult T‐cell leukemia/lymphoma (ATLL). Immunohistochemical analysis demonstrated TERT expression in 31% of AITL, 11% of PTCL‐NOS, and 5% of ATLL. Among them, AITL frequently showed high TERT expression with statistical significance. TERT promoter mutation analysis and genomic copy number evaluation were performed. TERT promoter mutation was observed in two cases of PTCL‐NOS (2/40) and not in other PTCLs. Genome copy number amplification was detected in 33% of PTCL‐NOS, 33% of AITL, and 50% of ATLL cases. We evaluated the relationship between the analyzed TERT genomic abnormalities and protein expression; however, no apparent relationship was observed. Furthermore, immunostaining showed TERT expression in the PTCL cytoplasm, suggesting the existence of mechanisms other than the maintenance of telomere length. Statistical analysis of the effect of TERT expression on the prognosis in PTCL cases revealed that TERT expression tended to have a poor prognosis in PTCL‐NOS. Since TERT expression was not an independent factor in multivariate analysis, further research will be needed to clarify the poor prognosis of PTCL‐NOS in TERT expression.

Tocotrienols Activate Nrf2 Nuclear Translocation and Increase the Antioxidant- Related Hepatoprotective Mechanism in Mice Liver

BACKGROUND

The most common preparation of tocotrienols is the Tocotrienol-Rich Fraction (TRF). This study aimed to investigate whether TRF induced liver Nrf2 nuclear translocation and influenced the expression of Nrf2-regulated genes.

METHODS

In the Nrf2 induction study, mice were divided into control, 2000 mg/kg TRF and diethyl maleate treated groups. After acute treatment, mice were sacrificed at specific time points. Liver nuclear extracts were prepared and Nrf2 nuclear translocation was detected through Western blotting. To determine the effect of increasing doses of TRF on the extent of liver nuclear Nrf2 translocation and its implication on the expression levels of several Nrf2-regulated genes, mice were divided into 5 groups (control, 200, 500 and 1000 mg/kg TRF, and butylated hydroxyanisole-treated groups). After 14 days, mice were sacrificed and liver RNA was extracted for qPCR assay.

RESULTS

2000 mg/kg TRF administration initiated Nrf2 nuclear translocation within 30 min, reached a maximum level of around 1 h and dropped to half-maximal levels by 24 h. Incremental doses of TRF resulted in dose-dependent increases in liver Nrf2 nuclear levels, along with concomitant dosedependent increases in the expressions of Nrf2-regulated genes.

CONCLUSION

TRF activated the liver Nrf2 pathway resulting in increased expression of Nrf2-regulated cytoprotective genes.

Age-Associated Proteomic Signatures and Potential Clinically Actionable Targets of Colorectal Cancer

The occurrence and prevalence of colorectal cancer (CRC) is closely associated with age. More than 90% of patients with CRC are diagnosed after 50 years of age. However, CRC incidence of young individuals has been increasing since 1990s, whereas the overall CRC frequency is declining. Distinct overall survival rates between young and aged patients with CRC have been established. Tremendous efforts have been made to clarify the underlying mechanisms of age-dependent clinical differences, but it still remains elusive. Here, we performed proteomic profiling of 50 patients with CRC and revealed proteomic signatures of CRC across age groups. Gene set enrichment analysis showed that distinct age-dependent clinical outcomes might mainly attribute to varied MYC targets V1/V2, E2F targets and G2M checkpoint gene sets, which were associated with cancer cell proliferation, cell apoptosis, tumor growth, and tumor metastasis. Multiple linear regression analysis revealed a large number of functional proteins, such as NOP2, CSE1L, NHP2, NOC2L and CDK1, with adjusted expression significantly correlated with age (p < 0.05). Among them, NHP2 is a core component of the telomerase complex associated with age. High NHP2 expression predicted poor overall survival, with a more significant correlation in aged patients with CRC. Knockdown of NHP2 significantly suppressed cancer cell proliferation. In addition, we revealed some age-related potential clinically actionable targets, such as PSEN1, TSPO, and CDK1, which might be more suitable for patients with late-onset CRC. Collectively, this study identifies age-associated proteomic signatures and potential therapeutic targets of CRC and may help make a precise decision on CRC treatment.

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The proteomic signatures of early-onset CRC are disclosed.

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Alterations of some proteins between cancerous and normal tissues are age-correlated.

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NHP2, overexpressed in tumors especially in aged patients, predicts poor prognosis.

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Potential age-dependent druggable targets and their inhibitors are summarized.

Telomere length determinants in childhood

Telomere length (TL) is a dynamic marker that reflects genetic predispositions together with the environmental conditions of an individual. It is closely related to longevity and a number of pathological conditions. Even though the extent of telomere research in children is limited compared to that of adults, there have been a substantial number of studies providing first insights into child telomere biology and determinants. Recent discoveries revealed evidence that TL is, to a great extent, determined already in childhood and that environmental conditions in adulthood have less impact than first believed. Studies have demonstrated that large inter-individual differences in TL are present among newborns and are determined by diverse factors that influence intrauterine development. The first years of child growth are associated with high cellular turnover, which results in fast shortening of telomeres. The rate of telomere loss becomes stable in early adulthood. In this review article we summarise the existing knowledge on telomere dynamics during the first years of childhood, highlighting the conditions that affect newborn TL. We also warn about the knowledge gaps that should be filled to fully understand the regulation of telomeres, in order to implement them as biomarkers for use in diagnostics or treatment.

[Molecular mechanisms of renal aging]

Chronic kidney disease (CKD) is characterized by the progressive decline of renal function, that occurs once a critical number of nephrons has been lost, regardless the etiology. CKD prevalence is constantly increasing, especially with age. Nevertheless, the molecular mechanisms underlying this progression are not very well known. With an increasing number of patients with CKD, especially elderly patients, it urges to better understand the pathophysiology of this progression to elaborate new therapeutic strategies. Recent works have highlighted the role of some cellular processes, such as senescence, during age-related kidney dysfunction. Senescence corresponds to a cellular state associated with a cell cycle blockade. Although the cell cannot proliferate, she is able to secrete a lot of proteins grouped under the term of senescence associated secretory phenotype (SASP). Identification of molecular mechansims involved in age related kidney dysfunction could help to determine new therapeutic targets.

Cancer-specific loss of TERT activation sensitizes glioblastoma to DNA damage

Glioblastoma is a highly lethal form of brain cancer with no current treatment options that substantially improve patient outcomes. A key therapeutic challenge is the identification of methods that reduce tumor burden while leaving normal cells unaffected. We show that TERT-promoter mutations, common in glioblastoma, lead to TERT reactivation through increased binding of GABPB1L-isoform–containing transcription factor complexes. In turn, we find that cancer-cell–specific inhibition of TERT through GABPB1L reduction results in near-term anti-growth effects and an impaired DNA damage response that profoundly increase the sensitivity of glioblastoma tumors to frontline chemotherapy. Our results thus provide rationale for GABPB1L inhibition combined with temozolomide chemotherapy treatment as a promising therapeutic strategy for glioblastoma.

Most glioblastomas (GBMs) achieve cellular immortality by acquiring a mutation in the telomerase reverse transcriptase (TERT) promoter. TERT promoter mutations create a binding site for a GA binding protein (GABP) transcription factor complex, whose assembly at the promoter is associated with TERT reactivation and telomere maintenance. Here, we demonstrate increased binding of a specific GABPB1L-isoform–containing complex to the mutant TERT promoter. Furthermore, we find that TERT promoter mutant GBM cells, unlike wild-type cells, exhibit a critical near-term dependence on GABPB1L for proliferation, notably also posttumor establishment in vivo. Up-regulation of the protein paralogue GABPB2, which is normally expressed at very low levels, can rescue this dependence. More importantly, when combined with frontline temozolomide (TMZ) chemotherapy, inducible GABPB1L knockdown and the associated TERT reduction led to an impaired DNA damage response that resulted in profoundly reduced growth of intracranial GBM tumors. Together, these findings provide insights into the mechanism of cancer-specific TERT regulation, uncover rapid effects of GABPB1L-mediated TERT suppression in GBM maintenance, and establish GABPB1L inhibition in combination with chemotherapy as a therapeutic strategy for TERT promoter mutant GBM.

Targeting MYC: From understanding its biology to drug discovery

The MYC oncogene is considered to be a high priority target for clinical intervention in cancer patients due to its aberrant activation in more than 50% of human cancers. Direct small molecule inhibition of MYC has traditionally been hampered by its intrinsically disordered nature and lack of both binding site and enzymatic activity. In recent years, however, a number of strategies for indirectly targeting MYC have emerged, guided by the advent of protein structural information and the growing set of computational tools that can be used to accelerate the hit to lead process in medicinal chemistry. In this review, we provide an overview of small molecules developed for clinical applications of these strategies, which include stabilization of the MYC guanine quadruplex, inhibition of BET factor BRD4, and disruption of the MYC:MAX heterodimer. The recent identification of novel targets for indirect MYC inhibition at the protein level is also discussed.

A Pan-Cancer Study of Somatic TERT Promoter Mutations and Amplification in 30,773 Tumors Profiled by Clinical Genomic Sequencing

TERT gene promoter mutations are known in multiple cancer types. Other TERT alterations remain poorly characterized. Sequencing data from 30,773 tumors analyzed by a hybridization capture next-generation sequencing assay (Memorial Sloan Kettering Cancer Center Integrated Mutation Profiling of Actionable Cancer Targets) were analyzed for the presence of TERT alterations. Promoter rearrangements (500 bases upstream of the transcriptional start site), hypermethylation (n = 57), and gene expression (n = 155) were evaluated for a subset of cases. Mutually exclusive and recurrent promoter mutations were identified at three hot spots upstream of the transcriptional start site in 11.3% of cases (-124: 74%; -146: 24%; and -138: <2%). Mutually exclusive amplification events were identified in another 2.3% of cases, whereas mutually exclusive rearrangements proximal to the TERT gene were seen in 24 cases. The highest incidence of TERT promoter mutations was seen in cutaneous melanoma (82%), whereas amplification events significantly outnumbered promoter mutations in well-differentiated/dedifferentiated liposarcoma (14.1% versus 2.4%) and adrenocortical carcinoma (13.6% versus 4.5%). Gene expression analysis suggests that the highest levels of gene expression are seen in cases with amplifications and rearrangements. Hypermethylation events upstream of the TERT coding sequence were not mutually exclusive with known pathogenic alterations. Studies aimed at defining the prevalence and prognostic impact of TERT alterations should incorporate other pathogenic TERT alterations as these may impact telomerase function.

Analysis of candidate genes expected to be essential for melanoma surviving

Introduction

Cancers may be treated by selective targeting of the genes vital for their survival. A number of attempts have led to discovery of several genes essential for surviving of tumor cells of different types. In this work, we tried to analyze genes that were previously predicted to be essential for melanoma surviving. Here we present the results of transient siRNA-mediated knockdown of the four of such genes, namely, UNC45A, STK11IP, RHPN2 and ZNFX1, in melanoma cell line A375, then assayed the cells for their viability, proliferation and ability to migrate in vitro. In our study, the knockdown of the genes predicted as essential for melanoma survival does not lead to statistically significant changes in cell viability. On the other hand, for each of the studied genes, mobility assays showed that the knockdown of each of the target genes accelerates the speed of cells migrating. Possible explanation for such counterintuitive results may include insufficiency of the predicting computational models or the necessity of a multiplex knockdown of the genes.

Aims

To examine the hypothesis of essentiality of hypomutated genes for melanoma surviving we have performed knockdown of several genes in melanoma cell line and analyzed cell viability and their ability to migrate.

Methods

Knockdown was performed by siRNAs transfected by Metafectene PRO. The levels of mRNAs before and after knockdown were evaluated by RT-qPCR analysis. Cell viability and proliferation were assessed by MTT assay. Cell migration was assessed by wound healing assay.

Results

The knockdown of the genes predicted as essential for melanoma survival does not lead to statistically significant changes in cell viability. On the other hand, for each of the studied genes, mobility assays showed that the knockdown of each of the target genes accelerates the speed of cells migrating.

Conclusion

Our results do not confirm initial hypothesis that the genes predicted essential for melanoma survival as a matter of fact support the survival of melanoma cells.

P-stereocontrolled synthesis of oligo(nucleoside N3'→O5' phosphoramidothioate)s - opportunities and limitations

3'-N-(2-Thio-1,3,2-oxathiaphospholane) derivatives of 5'-O-DMT-3'-amino-2',3'-dideoxy-ribonucleosides (NOTP-N), that bear a 4,4-unsubstituted, 4,4-dimethyl, or 4,4-pentamethylene substituted oxathiaphospholane ring, were synthesized. Within these three series, NOTP-N differed by canonical nucleobases (i.e., AdeBz, CytBz, GuaiBu, or Thy). The monomers were chromatographically separated into P-diastereomers, which were further used to prepare NNPSN' dinucleotides (3), as well as short P-stereodefined oligo(deoxyribonucleoside N3'→O5' phosphoramidothioate)s (NPS-) and chimeric NPS/PO- and NPS/PS-oligomers. The condensation reaction for NOTP-N monomers was found to be 5-6 times slower than the analogous OTP derivatives. When the 5'-end nucleoside of a growing oligomer adopts a C3'-endo conformation, a conformational 'clash' with the incoming NOTP-N monomer takes place, which is a main factor decreasing the repetitive yield of chain elongation. Although both isomers of NNPSN' were digested by the HINT1 phosphoramidase enzyme, the isomers hydrolyzed at a faster rate were tentatively assigned the R P absolute configuration. This assignment is supported by X-ray analysis of the protected dinucleotide DMTdGiBu NPSMeTOAc, which is P-stereoequivalent to the hydrolyzed faster P-diastereomer of dGNPST.

The secrets of telomerase: Retrospective analysis and future prospects

Telomerase plays a significant role to maintain and regulate the telomere length, cellular immortality and senescence by the addition of guanine-rich repetitive sequences. Chronic inflammation or oxidative stress-induced infection downregulates TERT gene modifying telomerase activity thus contributing to the early steps of gastric carcinogenesis process. Furthermore, telomere-telomerase system performs fundamental role in the pathogenesis and progression of diabetes mellitus as well as in its vascular intricacy. The cessation of cell proliferation in cultured cells by inhibiting the telomerase activity of transformed cells renders the rationale for culling of telomerase as a target therapy for the treatment of metabolic disorders and various types of cancers. In this article, we have briefly described the role of immune system and malignant cells in the expression of telomerase with critical analysis on the gaps and potential for future studies. The key findings regarding the secrets of the telomerase summarized in this article will help in future treatment modalities for the prevention of various types of cancers and metabolic disorders notably diabetes mellitus.

Enzyme-mimicking accelerated signal enhancement for visually multiplexed quantitation of telomerase activity

Here, we propose an amplification strategy involving enzyme-mimicking accelerated signal enhancement integrated with a triple-channel volumetric bar-chart chip for visually multiplexed quantitation of telomerase activity. This platform was used for evaluating the telomerase activities from different kinds of cells and a detection limit at the single-cell level was realized without any instrumental assistance.

Quantitative Detection and Imaging of Multiple Biological Molecules in Living Cells for Cell Screening

Because of insufficient information, a single biomarker is not sufficient for early diagnosis of cancer, whereas sensitive and selective detection of multiple biomolecules can significantly reduce analysis time, sample size, and accurately perform cell screening in early cancer. Therefore, the development of a noninvasive strategy that can simultaneously quantify multiple biomarkers (i.e., nucleic acids, proteins, and small molecules) in a single cell is particularly important. Herein, a universal sensing system (functional DNA@mesoporous silica nanoparticles (MSN)-Black Hole Quencher-rhodamine 6G (RhB), FDSBR), which is based on the combination of functionalized DNA and smart responsive nanomaterial, was successfully constructed. After incubation with the cells, different types of targets trigger the strand displacement reaction to release the fluorophore-labeled nucleic acids as the output signals to reflect the intracellular level of the telomerase and adenosine triphosphate (ATP), respectively. Simultaneously, intracellular miR-21 can be clearly indicated by the restored fluorescence of RhB when the caged double-stranded DNA was substituted into single-stranded DNA to open the pore. The concentrations of intracellular telomerase, miR-21, and ATP were identified successfully in three cell lines at the single-cell level. The results show that the contents of three biomolecules have significant differences in the three model cell lines and provide a promising route for developing innovative early disease diagnosis and cell screening assay.

Tumor-Oriented Telomerase-Terminated Nanoplatform as Versatile Strategy for Multidrug Resistance Reversal in Cancer Treatment

Multidrug resistance is one of the major problems in chemotherapy, and exploiting impactful targets to reverse drug resistance of most tumors remains a difficult problem. In this study, the tumor-oriented nanoparticle, BIBR1532-loaded peptide dendrimeric prodrug nanoassembly (B-PDPN), is used to assist telomerase inhibition for multidrug resistance reversal. B-PDPN possesses the characteristics of an acid-activated histidine to promote cellular uptake, a redox-sensitive poly(ethylene glycol) (PEG) layer to actualize endosomal escape and telomerase inhibitor release, and an acid sensitive chemical bond to facilitate chemotherapeutic drug release. Telomerase termination weakens the protective effect of hTERT protein on mitochondria and enhances reactive oxygen species (ROS) production, which increases DNA damage and apoptosis. The tumor-oriented nanoparticle B-PDPN achieves a broad-spectrum telomerase inhibition to combat multidrug resistance. In vivo experiments support the evidence that B-PDPN accumulates in the tumor site and reduces the expression of hTERT in tumor tissues to inhibit drug resistant tumor growth. This work introduces an innovative strategy of utilizing features of tumor-activated nanoplatform to assist telomerase termination. The nanoplatform enhances intracellular drug concentration and nucleus delivery of doxorubicin (DOX), and promotes DNA damage to combat multidrug resistance.

The mTOR pathway is necessary for survival of mice with short telomeres

Telomerase deficiency leads to age-related diseases and shorter lifespans. Inhibition of the mechanistic target of rapamycin (mTOR) delays aging and age-related pathologies. Here, we show that telomerase deficient mice with short telomeres (G2-Terc^−/−) have an hyper-activated mTOR pathway with increased levels of phosphorylated ribosomal S6 protein in liver, skeletal muscle and heart, a target of mTORC1. Transcriptional profiling confirms mTOR activation in G2-Terc^−/− livers. Treatment of G2-Terc^−/− mice with rapamycin, an inhibitor of mTORC1, decreases survival, in contrast to lifespan extension in wild-type controls. Deletion of mTORC1 downstream S6 kinase 1 in G3-Terc^−/− mice also decreases longevity, in contrast to lifespan extension in single S6K1^−/− female mice. These findings demonstrate that mTOR is important for survival in the context of short telomeres, and that its inhibition is deleterious in this setting. These results are of clinical interest in the case of human syndromes characterized by critically short telomeres.

Telomerase deficiency leads to age-related diseases and shortened lifespan, while inhibition of the mTOR pathway delays aging. Here, the authors show that inhibition of mTORC1 signaling shortens the lifespan of telomerase deficient mice.

Targeting DNA-PK in cancer

DNA-dependent protein kinase (DNA-PK) is involved in many cellular pathways. It has a key role in the cellular response to DNA damage, in the repair of DNA double-strand break (DNA-DSBs) and as a consequence an important role in maintaining genomic integrity. In addition, DNA-PK has been shown to modulate transcription, to be involved in the development of the immune system and to protect telomeres. These pleotropic involvements and the fact that its expression is de-regulated in cancer have made DNA-PK an intriguing therapeutic target in cancer therapy, especially when combined with agents causing DNA-DSBs such as topoisomerase II inhibitors and ionizing radiation. Different small molecule inhibitors of DNA-PK have been recently synthesized and some are now being tested in clinical trials. This review discusses what is known about DNA-PK, its role in tumor biology, DNA repair and cancer therapy and critically discusses its inhibition as a potential therapeutic approach.

DNA-dependent protein kinase in telomere maintenance and protection

This review focuses on DNA-dependent protein kinase (DNA-PK), which is the key regulator of canonical non-homologous end-joining (NHEJ), the predominant mechanism of DNA double-strand break (DSB) repair in mammals. DNA-PK consists of the DNA-binding Ku70/80 heterodimer and the catalytic subunit DNA-PKcs. They assemble at DNA ends, forming the active DNA-PK complex, which initiates NHEJ-mediated DSB repair. Paradoxically, both Ku and DNA-PKcs are associated with telomeres, and they play crucial roles in protecting the telomere against fusions. Herein, we discuss possible mechanisms and contributions of Ku and DNA-PKcs in telomere regulation.

Three-Dimensional Structure of RNA Monomeric G-Quadruplex Containing ALS and FTD Related G4C2 Repeat and Its Binding with TMPyP4 Probed by Homology Modeling based on Experimental Constraints and Molecular Dynamics Simulations

The G-quadruplex-forming hexanucleotide repeat expansion (HRE), d(G4C2)_n, within the human C9orf72 gene is the root cause for familial amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD). A recent study has shown that TMPyP4 has good potential to work as a RNA G-quadruplex binder in treating ALS and FTD. Although the high-resolution structure of the monomeric DNA antiparallel G-quadruplex form of the monomeric hexanucleotide repeat was recently solved, the RNA parallel G-quadruplex structure and its complex with TMPyP4 are not available yet. In this study, we first constructed the homology model for the parallel monomeric RNA G-quadruplex of r(G4C2)₃G4 based on experimental constraints and the parallel monomeric G-quadruplex DNA crystal structure. Although the G-tetra core of the homology model was stable observed in 15 μs molecular dynamics (MD) simulations, we observed that the loops adopt additional conformations besides the initial crystal conformation, where TMPyP4 binding was found to reduce the loop fluctuation of the RNA monomeric G-quadruplex. Next, we probed the elusive binding behavior of TMPyP4 to the RNA monomeric G-quadruplex. Encouragingly, the binding modes observed are similar to the modes observed in two experimental complexes of a parallel DNA G-quadruplex with TMPyP4. We also constructed a Markov state model to provide insights into the binding pathways. Together, the findings from our study may assist future development of G-quadruplex-specific ligands in the treatment of neurodegenerative diseases like ALS and FTD.

Oxoisoaporphines and Aporphines: Versatile Molecules with Anticancer Effects

Cancer is a disease that involves impaired genome stability with a high mortality index globally. Since its discovery, many have searched for effective treatment, assessing different molecules for their anticancer activity. One of the most studied sources for anticancer therapy is natural compounds and their derivates, like alkaloids, which are organic molecules containing nitrogen atoms in their structure. Among them, oxoisoaporphine and sampangine compounds are receiving increased attention due to their potential anticancer effects. Boldine has also been tested as an anticancer molecule. Boldine is the primary alkaloid extract from boldo, an endemic tree in Chile. These compounds and their derivatives have unique structural properties that potentially have an anticancer mechanism. Different studies showed that this molecule can target cancer cells through several mechanisms, including reactive oxygen species generation, DNA binding, and telomerase enzyme inhibition. In this review, we summarize the state-of-art research related to oxoisoaporphine, sampangine, and boldine, with emphasis on their structural characteristics and the relationship between structure, activity, methods of extraction or synthesis, and anticancer mechanism. With an effective cancer therapy still lacking, these three compounds are good candidates for new anticancer research.

Long telomeres and cancer risk: the price of cellular immortality

The distribution of telomere length in humans is broad, but it has finite upper and lower boundaries. Growing evidence shows that there are disease processes that are caused by both short and long telomere length extremes. The genetic basis of these short and long telomere syndromes may be linked to mutations in the same genes, such as the telomerase reverse transcriptase (TERT), but through differential effects on telomere length. Short telomere syndromes have a predominant degenerative phenotype marked by organ failure that most commonly manifests as pulmonary fibrosis and are associated with a relatively low cancer incidence. In contrast, insights from studies of cancer-prone families as well as genome-wide association studies (GWAS) have identified both rare and common variants that lengthen telomeres as being strongly associated with cancer risk. We have hypothesized that these cancers represent a long telomere syndrome that is associated with a high penetrance of cutaneous melanoma and chronic lymphocytic leukemia. In this Review, we will synthesize the clinical and human genetic observations with data from mouse models to define the role of telomeres in cancer etiology and biology.