Aloe emodin inhibits telomerase activity in breast cancer cells: transcriptional and enzymological mechanism

Regulation and clinical potential of telomerase reverse transcriptase (TERT/hTERT) in breast cancer

Telomerase reverse transcriptase (TERT/hTERT) serves as the pivotal catalytic subunit of telomerase, a crucial enzyme responsible for telomere maintenance and human genome stability. The high activation of hTERT, observed in over 90% of tumors, plays a significant role in tumor initiation and progression. An in-depth exploration of hTERT activation mechanisms in cancer holds promise for advancing our understanding of the disease and developing more effective treatment strategies. In breast cancer, the expression of hTERT is regulated by epigenetic, transcriptional, post-translational modification mechanisms and DNA variation. Besides its canonical function in telomere maintenance, hTERT exerts non-canonical roles that contribute to disease progression through telomerase-independent mechanisms. This comprehensive review summarizes the regulatory mechanisms governing hTERT in breast cancer and elucidates the functional implications of its activation. Given the overexpression of hTERT in most breast cancer cells, the detection of hTERT and its associated molecules are potential for enhancing early screening and prognostic evaluation of breast cancer. Although still in its early stages, therapeutic approaches targeting hTERT and its regulatory molecules show promise as viable strategies for breast cancer treatment. These methods are also discussed in this paper. Video Abstract.

Aloe-emodin targets multiple signaling pathways by blocking ubiquitin-mediated degradation of DUSP1 in nasopharyngeal carcinoma cells

Aloe-emodin (AE) has been shown to inhibit the proliferation of several cancer cell lines, including human nasopharyngeal carcinoma (NPC) cell lines. In this study, we confirmed that AE inhibited malignant biological behaviors, including cell viability, abnormal proliferation, apoptosis, and migration of NPC cells. Western blotting analysis revealed that AE upregulated the expression of DUSP1, an endogenous inhibitor of multiple cancer-associated signaling pathways, resulting in blockage of the extracellular signal-regulated kinase (ERK)-1/2, protein kinase B (AKT), and p38-mitogen activated protein kinase（p38-MAPK） signaling pathways in NPC cell lines. Moreover, the selective inhibitor of DUSP1, BCI-hydrochloride, partially reversed the AE-induced cytotoxicity and blocked the aforementioned signaling pathways in NPC cells. In addition, the binding between AE and DUSP1 was predicted via molecular docking analysis using AutoDock-Vina software and further verified via a microscale thermophoresis assay. The binding amino acid residues were adjacent to the predicted ubiquitination site (Lys192) of DUSP1. Immunoprecipitation with the ubiquitin antibody, ubiquitinated DUSP1 was shown to be upregulated by AE. Our findings revealed that AE can stabilize DUSP1 by blocking its ubiquitin-proteasome-mediated degradation and proposed an underlying mechanism by which AE-upregulated DUSP1 may potentially target multiple pathways in NPC cells.

Investigation of the Interaction between Aloe vera Anthraquinone Metabolites and c-Myc and C-Kit G-Quadruplex DNA Structures

G-quadruplexes are nucleotide sequences present in the promoter region of numerous oncogenes, having a key role in the suppression of gene transcription. Recently, the binding of anthraquinones from Aloe vera to G-quadruplex structures has been studied through various physico-chemical techniques. Intrigued by the reported results, we investigated the affinity of aloe emodin, aloe emodin-8-glucoside, and aloin to selected G-quadruplex nucleotide sequences by NMR spectroscopy. The structural determinants for the formation of the ligand/nucleotide complexes were elucidated and a model of the interactions between the tested compounds and C-Kit and c-Myc G-quadruplex DNA structures was built by integrated NMR and molecular modeling studies. Overall, the obtained results confirmed and implemented the previously reported findings, pointing out the complementarity of the different approaches and their contribution to a more detailed overview of the ligand/nucleotide complex formation. Furthermore, the proposed models of interaction could pave the way to the design of new nature-derived compounds endowed with increased G-quadruplex stabilizing activity.

How Should the Worldwide Knowledge of Traditional Cancer Healing Be Integrated with Herbs and Mushrooms into Modern Molecular Pharmacology?

Traditional herbal medicine (THM) is a “core” from which modern medicine has evolved over time. Besides this, one third of people worldwide have no access to modern medicine and rely only on traditional medicine. To date, drugs of plant origin, or their derivates (paclitaxel, vinblastine, vincristine, vinorelbine, etoposide, camptothecin, topotecan, irinotecan, and omacetaxine), are very important in the therapy of malignancies and they are included in most chemotherapeutic regimes. To date, 391,000 plant and 14,000 mushroom species exist. Their medical and biochemical capabilities have not been studied in detail. In this review, we systematized the information about plants and mushrooms, as well as their active compounds with antitumor properties. Plants and mushrooms are divided based on the regions where they are used in ethnomedicine to treat malignancies. The majority of their active compounds with antineoplastic properties and mechanisms of action are described. Furthermore, on the basis of the available information, we divided them into two priority groups for research and for their potential of use in antitumor therapy. As there are many prerequisites and some examples how THM helps and strengthens modern medicine, finally, we discuss the positive points of THM and the management required to transform and integrate THM into the modern medicine practice.

Guanine quadruplexes in the RNA genome of the tick-borne encephalitis virus: their role as a new antiviral target and in virus biology

We have identified seven putative guanine quadruplexes (G4) in the RNA genome of tick-borne encephalitis virus (TBEV), a flavivirus causing thousands of human infections and numerous deaths every year. The formation of G4s was confirmed by biophysical methods on synthetic oligonucleotides derived from the predicted TBEV sequences. TBEV-5, located at the NS4b/NS5 boundary and conserved among all known flaviviruses, was tested along with its mutated variants for interactions with a panel of known G4 ligands, for the ability to affect RNA synthesis by the flaviviral RNA-dependent RNA polymerase (RdRp) and for effects on TBEV replication fitness in cells. G4-stabilizing TBEV-5 mutations strongly inhibited RdRp RNA synthesis and exhibited substantially reduced replication fitness, different plaque morphology and increased sensitivity to G4-binding ligands in cell-based systems. In contrast, strongly destabilizing TBEV-5 G4 mutations caused rapid reversion to the wild-type genotype. Our results suggest that there is a threshold of stability for G4 sequences in the TBEV genome, with any deviation resulting in either dramatic changes in viral phenotype or a rapid return to this optimal level of G4 stability. The data indicate that G4s are critical elements for efficient TBEV replication and are suitable targets to tackle TBEV infection.

Overview of the Biological Activity of Anthraquinons and Flavanoids of the Plant Rumex Species

Rumex confertus belongs to the genus Rumex and is classified as an invasive parasitic plant in agriculture. Despite other Rumex species being widely used in herbal medicine due to their antimicrobial, antioxidant, antitumor, and anti-inflammatory effects, there are almost no information about the potential of Rumex confertus for the treatment of various diseases. In this review we analyzed scientific articles revealing properties of Rumex plant’s substances against cancer, diabetes, pathogenic bacterial invasions, viruses, inflammation, and oxidative stress for the past 20 years. Compounds dominating in each composition of solvents for extraction were discussed, and common thin layer chromatography(TLC) and high performance liquid chromatography(HPLC) methods for efficient separation of the plant’s extract are included. Physico-chemical properties such as solubility, hydrophobicity (Log P), pKa of flavonoids, anthraquinones, and other derivatives are very important for modeling of pharmacokinetic and pharmacodynamics. An overview of clinical studies for abounded selected substances of Rumex species is presented.

Cerebroprotective effect of Aloe Emodin: In silico and in vivo studies

This study involved cerebroprotective potential of aloe emodin (AE) by in silico molecular docking analysis against various cerebrotoxic proteins followed by in vivo activity on multiple occlusions and reperfusion of bilateral carotid arteries (MO/RCA) induced cerebral injury in experimental rats. Molecular docking studies were carried out to evaluate the binding affinity (or binding interaction) between AE and various proteins involved in apoptosis such as caspase-3 (CASP3) and Bcl-2-associated X protein (BAX), and proteins involved in inflammation such as interleukin-6 (IL-6), tumor necrosis factor α (TNF α), nitric oxide synthase (NOS), acid-sensing ion channel (ASIC) and glutamate receptor (GR) involved in cerebral stroke, and results were compared with that of standard drugs, minocycline, quercetin, and memantine. Cerebral ischemic reperfusion induced by MO/RCA was assessed for 10 mins reperfusion period as one cycle, and the experiment was conducted for up to 3 cycles in rats. After completion of 3 cycles, the rats were subjected to ethically acceptable animal euthanasia followed by isolation of the brains which were studied for the size of cerebral infarction, and biochemical parameters such as glutathione (GSH), malondialdehyde (MDA), catalase (CAT) were estimated from the brain homogenate. Further, histological studies were done to study neuronal contact. Results of molecular docking indicated that the AE exhibited interaction with active sites of cerebrotoxic proteins usually involved in protein functions or cerebrotoxicity. Biochemical results showed that in the untreated brain, MDA levels increased significantly, and decreased GSH and CAT levels were observed when compared to MO/RCA group, while treated rats showed a decrease in the levels of MDA and an increase in GSH and CAT levels as compared to MO/RCA rats. In comparison with sham rats and normal rats, histopathological analysis revealed neuronal damage in MO/RCA surgery rats which manifested as decreased intact neurons. However, treatment with AE 50 mg/kg b.wt. restored contact between neuronal cells. It can be concluded that AE showed cerebroprotective effect on RO/RCA with promising inhibition of cerebrotoxic proteins (apoptotic and neuroinflammatory) as evident from molecular docking studies. The cerebroprotective potential of AE could be due to its anti-inflammatory, antioxidant, and antiapoptotic principles.

Advances in Understanding the Role of Aloe Emodin and Targeted Drug Delivery Systems in Cancer

Cancer is one of the important causes of death worldwide. Despite remarkable improvements in cancer research in the past few decades, several cancer patients still cannot be cured owing to the development of drug resistance. Natural sources might have prominence as potential drug candidates. Among the several chemical classes of natural products, anthraquinones are characterized by their large structural variety, noticeable biological activity, and low toxicity. Aloe emodin, an anthraquinone derivative, is a natural compound found in the roots and rhizomes of many plants. This compound has proven its antineoplastic, anti-inflammatory, antiangiogenic, and antiproliferative potential as well as ability to prevent cancer metastasis and potential in reversing multidrug resistance of cancer cells. The anticancer property of aloe emodin, a broad-spectrum inhibitory agent of cancer cells, has been detailed in many biological pathways. In cancer cells, these molecular mechanisms consist of inhibition of cell growth and proliferation, cell cycle arrest deterioration, initiation of apoptosis, antimetastasis, and antiangiogenic effect. In accordance with the strategy of developing potential drug candidates from natural products, aloe emodin's low bioavailability has been tried to be overcome by structural modifications and nanocarrier systems. Consequently, this review summarizes the antiproliferative and anticarcinogenic properties of aloe emodin, as well as the enhanced activity of its derivatives and the advantages of drug delivery systems on bioavailability.

Journey of anthraquinones as anticancer agents - a systematic review of recent literature

Anthraquinones are privileged chemical scaffolds that have been used for centuries in various therapeutic applications. The anthraquinone moiety forms the core of various anticancer agents. However, the emergence of drug-resistant cancers warrants the development of new anticancer agents. The research endeavours towards new anthraquinone-based compounds are increasing rapidly in recent years. They are used as a core chemical template to achieve structural modifications, resulting in the development of new anthraquinone-based compounds as promising anticancer agents. Mechanistically, most of the anthraquinone-based compounds inhibit cancer progression by targeting essential cellular proteins. Herein, we review new anthraquinone analogues that have been developed in recent years as anticancer agents. This includes a systematic review of the recent literature (2005-2021) on anthraquinone-based compounds in cell-based models and key target proteins such as kinases, topoisomerases, telomerases, matrix metalloproteinases and G-quadruplexes involved in the viability of cancer cells. In addition to this, the developments in PEG-based delivery of anthraquinones and the toxicity aspects of anthraquinone derivatives are also discussed. The review dispenses a compact background knowledge to understanding anthraquinones for future research on the expansion of anticancer therapeutics.

Natural Bioactive Compounds Targeting Epigenetic Pathways in Cancer: A Review on Alkaloids, Terpenoids, Quinones, and Isothiocyanates

Cancer is one of the most complex and systemic diseases affecting the health of mankind, causing major deaths with a significant increase. This pathology is caused by several risk factors, of which genetic disturbances constitute the major elements, which not only initiate tumor transformation but also epigenetic disturbances which are linked to it and which can induce transcriptional instability. Indeed, the involvement of epigenetic disturbances in cancer has been the subject of correlations today, in addition to the use of drugs that operate specifically on different epigenetic pathways. Natural molecules, especially those isolated from medicinal plants, have shown anticancer effects linked to mechanisms of action. The objective of this review is to explore the anticancer effects of alkaloids, terpenoids, quinones, and isothiocyanates.

Binding Studies of Aloe-Active Compounds with G-Quadruplex Sequences

G-quadruplex, a unique DNA quartet motif with a pivotal role in regulation of the gene expression, has been established as a potent therapeutic target for the treatment of cancer. Small-molecule-mediated stabilization of the G-quadruplex and thus inhibition of the expression from the oncogene promoter and telomere region may be a promising anticancer strategy. Aloe vera-derived natural compounds like aloe emodin, aloe emodin-8-glucoside, and aloin have significant anticancer activity. Comparative binding studies of these three molecules with varieties of G-quadruplex sequences were carried out using different biophysical techniques like absorption spectral titration, fluorescence spectral titration, dye displacement, ferrocyanide quenching assay, and CD and DSC thermogram studies. Overall, this study revealed aloe emodin and aloe emodin-8-glucoside as potent quadruplex-binding molecules mostly in the case of c-KIT and c-MYC sequences with a binding affinity value of 10⁵ order that is higher than their duplex DNA binding ability. This observation may be correlated to the anticancer activity of these aloe-active compounds and also be helpful in the potential therapeutic application of natural compound-based molecules.

Aloe and its Effects on Cancer: A Narrative Literature Review

Many years ago, Aloe Vera was cited to have a lot of therapeutic properties including; anti-microbial, anti-viral, anti-cancer, anti-oxidant, anti-inflammatory, skin protection, wound healing, and regulation of blood glucose and cholesterol. However, Aloe could present some side effects. This review focused on the latest discoveries regarding the therapeutic role of Aloe plant or its compounds on the acquired biological capabilities for tumour growth and progression namely; evading growth suppressor, avoiding immune destruction, enabling replicative immortality, tumour promoting inflammation, activating invasion and metastasis, inducing angiogenesis, genome instability and mutation, resisting cell death, deregulating cellular energetics and sustaining proliferating signalling. It clarified the anti-cancer activities it exerts on different types of cancer and also highlighted some pro-oncogenic pathways that can be disrupted by different compounds of Aloe.

hTERT Promotes CRC Proliferation and Migration by Recruiting YBX1 to Increase NRF2 Expression

High human telomerase reverse transcriptase (hTERT) expression is related to severe Colorectal Cancer (CRC) progression and negatively related to CRC patient survival. Previous studies have revealed that hTERT can reduce cancer cellular reactive oxygen species (ROS) levels and accelerate cancer progression; however, the mechanism remains poorly understood. NFE2-related factor 2 (NRF2) is a molecule that plays a significant role in regulating cellular ROS homeostasis, but whether there is a correlation between hTERT and NRF2 remains unclear. Here, we showed that hTERT increases CRC proliferation and migration by inducing NRF2 upregulation. We further found that hTERT increases NRF2 expression at both the mRNA and protein levels. Our data also revealed that hTERT primarily upregulates NRF2 by increasing NRF2 promoter activity rather than by regulating NRF2 mRNA or protein stability. Using DNA pull-down/MS analysis, we found that hTERT can recruit YBX1 to upregulate NRF2 promoter activity. We also found that hTERT/YBX1 may localize to the P2 region of the NRF2 promoter. Taken together, our results demonstrate that hTERT facilitates CRC proliferation and migration by upregulating NRF2 expression through the recruitment of the transcription factor YBX1 to activate the NRF2 promoter. These results provide a new theoretical basis for CRC treatment.