Telomerase: A prominent oncological target for development of chemotherapeutic agents

TERC promotes non-small cell lung cancer progression by facilitating the nuclear localization of TERT

The core of telomerase consists of the protein subunit telomerase reverse transcriptase (TERT) and the telomerase RNA component (TERC). So far, the role of TERC in cancer development has remained elusive. Here, we found TERC expression elevated in non-small cell lung cancer (NSCLC) tissues, which was associated with disease progression and poor prognosis in patients. Using NSCLC cell lines and xenograft models, we showed that knockdown of TERC caused cell cycle arrest, and inhibition of cell proliferation and migration. Mechanistically, TERC was exported to the cytoplasm by nuclear RNA export factor 1 (NXF1), where it mediated the interaction of TERT with other telomerase subunits. Depletion of TERC hindered the assembly and subsequent nuclear localization of the telomerase complex, preventing TERT from functioning in telomere maintenance and transcription regulation. Our findings suggest that TERC is a potential biomarker for NSCLC diagnosis and prognosis and can be a target for NSCLC treatment.

New insights from bidirectional Mendelian randomization: causal relationships between telomere length and mitochondrial DNA copy number in aging biomarkers

Mitochondrial DNA (mtDNA) copy number and telomere length (TL) are dynamic factors that have been linked to the aging process in organisms. However, the causal relationship between these variables remains uncertain. In this research, instrumental variables (IVs) related to mtDNA copy number and TL were obtained from publicly available genome-wide association studies (GWAS). Through bidirectional Mendelian randomization (MR) analysis, we examined the potential causal relationship between these factors. The forward analysis, with mtDNA copy number as the exposure and TL as the outcome, did not reveal a significant effect (B=-0.004, P>0.05). On the contrary, upon conducting a reverse analysis, it was found that there exists a positive causal relationship (B=0.054, P<0.05). Sensitivity analyses further confirmed the reliability of these results. The outcomes of this study indicate a one-way positive causal relationship, indicating that telomere shortening in the aging process may lead to a decrease in mtDNA copy number, providing new perspectives on their biological mechanisms.

Drug repurposing for cancer therapy

Cancer, a complex and multifactorial disease, presents a significant challenge to global health. Despite significant advances in surgical, radiotherapeutic and immunological approaches, which have improved cancer treatment outcomes, drug therapy continues to serve as a key therapeutic strategy. However, the clinical efficacy of drug therapy is often constrained by drug resistance and severe toxic side effects, and thus there remains a critical need to develop novel cancer therapeutics. One promising strategy that has received widespread attention in recent years is drug repurposing: the identification of new applications for existing, clinically approved drugs. Drug repurposing possesses several inherent advantages in the context of cancer treatment since repurposed drugs are typically cost-effective, proven to be safe, and can significantly expedite the drug development process due to their already established safety profiles. In light of this, the present review offers a comprehensive overview of the various methods employed in drug repurposing, specifically focusing on the repurposing of drugs to treat cancer. We describe the antitumor properties of candidate drugs, and discuss in detail how they target both the hallmarks of cancer in tumor cells and the surrounding tumor microenvironment. In addition, we examine the innovative strategy of integrating drug repurposing with nanotechnology to enhance topical drug delivery. We also emphasize the critical role that repurposed drugs can play when used as part of a combination therapy regimen. To conclude, we outline the challenges associated with repurposing drugs and consider the future prospects of these repurposed drugs transitioning into clinical application.

Synthesis of the Reducing-end Hexasaccharide Fragment of Marine Lipopolysaccharide Axinelloside A

Chemical synthesis of an orthogonally protected hexasaccharide relevant to the reducing-end half of axinelloside A, a highly sulfated marine lipopolysaccharide, is disclosed. The synthesis features preparation of the scyllo-inositol unit via a Ferrier-type-II rearrangement, construction of the 1,2-cis-glycosidic bonds via remote participation, and concise [2+2+2] assembly via Au(I)-catalyzed glycosylation.

Berberine and RNAi-Targeting Telomerase Reverse Transcriptase (TERT) and/or Telomerase RNA Component (TERC) Caused Oxidation in Colorectal Cancer Cell Line, HCT 116: An Integrative Approach using Molecular and Metabolomic Studies

Colorectal cancer (CRC) is the most common cancer in both men and women and is associated with increased telomerase levels and activity. The potential downstream effects of TERT and/or TERC downregulation by berberine (a telomerase inhibitor) or RNA interference (RNAi) on various target RNAs, proteins, relative telomerase activity (RTA), relative telomere length (RTL), hydrogen peroxide concentration [H2O2], percentage of cell cycle distribution, cell size and granularity as well as cellular metabolites were explored in HCT 116 cell line. Knockdown of TERT decreased TERC. The downregulation of TERT and/or TERC caused increment of [H2O2], G0/G1 phase arrest in addition to decreased S and G2/M phases, as well as diminished cell size. RTL was later reduced as a result of TERT, TERT and/or TERC downregulation which decreased RTA. It was discovered that xanthine oxidase (XO) was significantly and positively correlated at FDR-adjusted p value < 0.05 with RTA, TERT, TERT, TERC, and RTL. HCT 116 with decreased RTA was closely clustered in the Principal Component Analysis (PCA) indicating similarity of the metabolic profile. A total of 55 metabolites were putatively annotated in this study, potentially associated with RTA levels. The Debiased Sparse Partial Correlation (DSPC) Network revealed that RTA was directly correlated to TERT. There were 4 metabolic pathways significantly affected by low level of RTA which include (1) purine metabolism, (2) glycine, serine, and threonine metabolism, (3) glyoxylate and dicarboxylate metabolism, and (4) aminoacyl-tRNA biosynthesis. The Gene-Metabolite Interaction Network implied that reduced RTA level was related to the mechanism of oxidative stress. This study reveals the linkages between RTA to various selected RNAs, proteins, metabolites, oxidative stress mechanism and subsequently phenotypic changes in HCT 116 which is valuable to understand the intricate biological interactions and mechanism of telomerase in CRC.

Marine-Derived Bisindoles for Potent Selective Cancer Drug Discovery and Development

Marine-derived bisindoles exhibit structural diversity and exert anti-cancer influence through multiple mechanisms. Comprehensive research has shown that the development success rate of drugs derived from marine natural products is four times higher than that of other natural derivatives. Currently, there are 20 marine-derived drugs used in clinical practice, with 11 of them demonstrating anti-tumor effects. This article provides a thorough review of recent advancements in anti-tumor exploration involving 167 natural marine bisindole products and their derivatives. Not only has enzastaurin entered clinical practice, but there is also a successfully marketed marine-derived bisindole compound called midostaurin that is used for the treatment of acute myeloid leukemia. In summary, investigations into the biological activity and clinical progress of marine-derived bisindoles have revealed their remarkable selectivity, minimal toxicity, and efficacy against various cancer cells. Consequently, they exhibit immense potential in the field of anti-tumor drug development, especially in the field of anti-tumor drug resistance. In the future, these compounds may serve as promising leads in the discovery and development of novel cancer therapeutics.

Current research status of tumor cell biomarker detection

With the annual increases in the morbidity and mortality rates of tumors, the use of biomarkers for early diagnosis and real-time monitoring of tumor cells is of great importance. Biomarkers used for tumor cell detection in body fluids include circulating tumor cells, nucleic acids, protein markers, and extracellular vesicles. Among them, circulating tumor cells, circulating tumor DNA, and exosomes have high potential for the prediction, diagnosis, and prognosis of tumor diseases due to the large amount of valuable information on tumor characteristics and evolution; in addition, in situ monitoring of telomerase and miRNA in living cells has been the topic of extensive research to understand tumor development in real time. Various techniques, such as enzyme-linked immunosorbent assays, immunoblotting, and mass spectrometry, have been widely used for the detection of these markers. Among them, the detection of tumor cell markers in body fluids based on electrochemical biosensors and fluorescence signal analysis is highly preferred because of its high sensitivity, rapid detection and portable operation. Herein, we summarize recent research progress in the detection of tumor cell biomarkers in body fluids using electrochemical and fluorescence biosensors, outline the current research status of in situ fluorescence monitoring and the analysis of tumor markers in living cells, and discuss the technical challenges for their practical clinical application to provide a reference for the development of new tumor marker detection methods.

Reaction of human telomeric unit TTAGGG and a photoactivatable Pt(IV) anticancer prodrug

The interaction of a photoactivatable diazidodihydroxido Pt(IV) prodrug, trans,trans,trans-[Pt(N3)2(OH)2(py)2] (py = pyridine; 1), with a hexamer straight human telomeric DNA unit sequence (5'-T1T2A3G4G5G6-3', I) upon light irradiation was investigated by electrospray ionization mass spectroscopy (ESI-MS). In the primary mass spectrum, two major mono-platinated I adducts with the bound Pt moieties, trans-[PtII(N3)(py)2]+ (1') and trans-[PtII(py)2]2+ (1''), respectively, were detected. It is rare to observe such high abundance and nearly equal intensity platinated DNA adducts formed by these two PtII species because 1' is usually the only major reduced Pt(II) species produced by the photodecomposition of complex 1 in the presence of DNA while 1'' was rarely detected as the major reduced PtII species reported previously. Subsequent tandem mass spectrometric analysis by collision-induced dissociation (CID) showed that in the former adduct {I + 1'}2+, G6 and A3 were the platination sites. While in the latter adduct {I + 1''}2+, a potential intrastrand crosslink was speculated after G4 and G6 sites were identified. Additionally, other minor platinated adducts like di-platinated I adduct by 1' with platination sites at G4 and G6 and mono-platinated I adducts containing base oxidation were also detected by mass spectrometry. Due to the rich guanines and their sensitivity to oxidation, the oxidation induced by 1 most probably occurred at guanine. The oxidation adducts were proposed as 8-hydroxyl guanine, spiroiminodihydantoin (Sp), 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyG), 5-guanidinohydantoin (Gh), and/or dehydroguanidinohydantoin (DGh) referring to previous reports. The obtained results provide useful chemical information about the photoreaction between photoactivatable Pt(IV) anticancer prodrugs and human telomeric DNA. Such special damages of Pt(IV) prodrugs on human telomeric DNA implicate its active role in the mechanism of Pt(IV) prodrugs and further support the unique sequence-dependent photointeraction profile of complex 1 reacting with DNA.