Onopordopicrin from the new genus Shangwua as a novel thioredoxin reductase inhibitor to induce oxidative stress-mediated tumor cell apoptosis

Thioredoxin (Trx): A redox target and modulator of cellular senescence and aging-related diseases

Thioredoxin (Trx) is a compact redox-regulatory protein that modulates cellular redox state by reducing oxidized proteins. Trx exhibits dual functionality as an antioxidant and a cofactor for diverse enzymes and transcription factors, thereby exerting influence over their activity and function. Trx has emerged as a pivotal biomarker for various diseases, particularly those associated with oxidative stress, inflammation, and aging. Recent clinical investigations have underscored the significance of Trx in disease diagnosis, treatment, and mechanistic elucidation. Despite its paramount importance, the intricate interplay between Trx and cellular senescence-a condition characterized by irreversible growth arrest induced by multiple aging stimuli-remains inadequately understood. In this review, our objective is to present a comprehensive and up-to-date overview of the structure and function of Trx, its involvement in redox signaling pathways and cellular senescence, its association with aging and age-related diseases, as well as its potential as a therapeutic target. Our review aims to elucidate the novel and extensive role of Trx in senescence while highlighting its implications for aging and age-related diseases.

Cerebral neurotoxicity of amino-modified polystyrene nanoplastics in mice and the protective effects of functional food Camellia pollen

Accumulating evidence suggests that nanoplastics contribute to an increased risk of brain damage, however, the precise underlying mechanisms remain unclear. Here, we subjected mice to long-term exposure to amino-modified polystyrene nanoplastics (APS-NPs). These nanoplastics were detected in the mouse brain; coupled with the observed upregulation of Alzheimer's disease-associated genes (APP and MAPT). To further explore nanoplastic damage mechanisms and the corresponding protective strategies against these mechanisms in vitro, we used hCMEC/D3 and HT22 cells. Results showed that APS-NPs disrupted tight junction proteins (Occludin and ZO-1) via TLR2/MMP9 axis, resulting in blood-brain barrier permeation; this was significantly mitigated by functional food Camellia pollen treatment. APS-NPs initiated iNOS and nNOS upregulation within neurons resulting in Sirtuin 1 deacetylase inactivation and CBP acetyltransferase stimulation, ultimately leading to Ac-Tau formation. This process was attenuated by Camellia pollen, which also ameliorated the APS-NPs-induced neuronal apoptosis mediated by the p53/Bax/Bcl-2 axis. Network pharmacology analysis of Camellia pollen offered a further theoretical understanding of its potential applications in preventing and treating nervous system disorders, such as Alzheimer's disease. This study established that Camellia pollen protects the brain against APS-NPs-mediated blood-brain barrier damage and alleviates neuronal apoptosis and Alzheimer's disease-like neurotoxicity. This study elucidates the mechanisms underlying polystyrene-induced brain damage and can be used to inform future prevention and treatment strategies.

Selenoproteins in Health

Selenium (Se) is a naturally occurring essential micronutrient that is required for human health. The existing form of Se includes inorganic and organic. In contrast to the inorganic Se, which has low bioavailability and high cytotoxicity, organic Se exhibits higher bioavailability, lower toxicity, and has a more diverse composition and structure. This review presents the nutritional benefits of Se by listing and linking selenoprotein (SeP) functions to evidence of health benefits. The research status of SeP from foods in recent years is introduced systematically, particularly the sources, biochemical transformation and speciation, and the bioactivities. These aspects are elaborated with references for further research and utilization of organic Se compounds in the field of health.

Upgrade of chrysomycin A as a novel topoisomerase II inhibitor to curb KRAS-mutant lung adenocarcinoma progression

A primary strategy employed in cancer therapy is the inhibition of topoisomerase II (Topo II), implicated in cell survival. However, side effects and adverse reactions restrict the utilization of Topo II inhibitors. Thus, investigations focus on the discovery of novel compounds that are capable of inhibiting the Topo II enzyme and feature safer toxicological profiles. Herein, we upgrade an old antibiotic chrysomycin A from Streptomyces sp. 891 as a compelling Topo II enzyme inhibitor. Our results show that chrysomycin A is a new chemical entity. Notably, chrysomycin A targets the DNA-unwinding enzyme Topo II with an efficient binding potency and a significant inhibition of intracellular enzyme levels. Intriguingly, chrysomycin A kills KRAS-mutant lung adenocarcinoma cells and is negligible cytotoxic to normal cells at the cellular level, thus indicating a capability of potential treatment. Furthermore, mechanism studies demonstrate that chrysomycin A inhibits the Topo II enzyme and stimulates the accumulation of reactive oxygen species, thereby inducing DNA damage-mediated cancer cell apoptosis. Importantly, chrysomycin A exhibits excellent control of cancer progression and excellent safety in tumor-bearing models. Our results provide a chemical scaffold for the synthesis of new types of Topo II inhibitors and reveal a novel target for chrysomycin A to meet its further application.

Toxicological differences of trifloxystrobin and kresoxim-methyl on zebrafish in various levels of exposure routes, organs, cells and biochemical indicators

Trifloxystrobin (TRI) and kresoxim-methyl (KRE), as quinone outside inhibitor fungicides (QoIs), have broad applications due to their effective activity against fungi. Excessive usages of agrochemicals trigger environmental risks, such as aquatic organisms (fish). Research performed in recent years has focused on the ecotoxicology of TRI and KRE in fish containing histologic morphology, enzyme activity, protein and gene expression under chronic toxicity conditions, whereas less is known about the underlying mechanisms of toxicity and differences between TRI and KRE in fish under acute toxicity conditions. In the present study, in comparison to different exposure routes [whole-body exposure (WBE), head exposure (HE), trunk exposure (TE), and Oral administration (OA)], the external substances TRI and KRE entered the fish body mainly via gill organs and led to fish toxicity. Furthermore, gill organs and gill cells were vulnerable to TRI and KRE exposure, which indicated that the gill is a vital impaired organ. The 96 h-LC₅₀ (sublethal concentration) value of KRE was 289.8 μg L^-1 (R² = 0.9855) with an approximate 10-fold difference in TRI toxicity. The cytotoxicity exposed to TRI was higher than that in KRE at the same concentration. The potential mechanisms of toxic differences could be various toxic effects in terms of MCIII (mitochondrial complex III) activity, ATP (Adenosine triphosphate) content, MA (mitochondrial activity), ROS (reactive oxygen species) levels, and cellular respiration. Furthermore, the disorder in MCIII activity was probably the main potential mechanisms of toxic differences. To some extent, this research provides not only new insight into the underlying toxic mechanism of TRI and KRE in fish but also a basis for the guidance of agrochemicals considering aquatic risks.

Revealing PACMA 31 as a new chemical type TrxR inhibitor to promote cancer cell apoptosis

Thioredoxin reductase (TrxR) is a pivotal regulator of redox homeostasis, while dysregulation of redox homeostasis is a hallmark for cancer cells. Thus, there is considerable potential to inhibit the aberrantly upregulated TrxR in cancer cells to discover selective cancer therapeutic agents. Nevertheless, the structural types of TrxR inhibitors presented currently are still relatively limited. We herein report that PACMA 31, previously reported to inhibit protein disulfide isomerase (PDI), is a potent TrxR inhibitor. PACMA 31 possesses a pharmacophore scaffold that is structurally different from the announced TrxR inhibitors and exhibits effective cytotoxicity against cervical cancer cells. Our results reveal that PACMA 31 selectively inhibits TrxR over the related glutathione reductase (GR) and in the presence of reduced glutathione (GSH). Further studies with mutant enzyme and molecular docking suggest that the propynamide fragment of PACMA 31 interacts covalently with the selenocysteine residue of TrxR. Moreover, PACMA 31 effectively and selectively curbs TrxR activity in cells and further stimulates the production of reactive oxygen species (ROS) at low micromolar concentrations, which in turn triggers the accumulation of oxidized thioredoxin (Trx) and GSSG in cells. Follow-up studies demonstrate that PACMA 31 targets TrxR in cells to induce oxidative stress-mediated cancer cell apoptosis. Our results provide a new structural type of TrxR inhibitor that may serve as a useful probe for investigating the biology of TrxR-implicated pathways, and uncover a new target of PACMA 31 that contributes to it becoming a candidate for cancer treatment.

NO news: S-(de)nitrosylation of cathepsins and their relationship with cancer

Tumor formation and progression have been much of a study over the last two centuries. Recent studies have seen different developments for the early diagnosis and treatment of the disease; some of which even promise survival of the patient. Cysteine proteases, mainly cathepsins have been unequivocally identified as putative worthy players of redox imbalance that contribute to the premonition and further progression of cancer by interfering in the normal extracellular and intracellular proteolysis and initiating a proteolytic cascade. The present review article focuses on the study of cancer so far, while establishing facts on how future studies focused on the cellular interrelation between nitric oxide (NO) and cancer, can direct their focus on cathepsins. For a tumor cell to thrive and synergize a cancerous environment, different mutations in the proteolytic and signaling pathways and the proto-oncogenes, oncogenes, and the tumor suppressor genes are made possible through cellular biochemistry and some cancer-stimulating environmental factors. The accumulated findings show that S-nitrosylation of cathepsins under the influence of NO-donors can prevent the invasion of cancer and cause cancer cell death by blocking the activity of cathepsins as well as the major denitrosylase systems using a multi-way approach. Faced with a conundrum of how to fill the gap between the dodging of established cancer hallmarks with cathepsin activity and gaining appropriate research/clinical accreditation using our hypothesis, the scope of this review also explores the interplay and crosstalk between S-nitrosylation and S-(de)nitrosylation of this protease and highlights the utility of charging thioredoxin (Trx) reductase inhibitors, low-molecular-weight dithiols, and Trx mimetics using efficient drug delivery system to prevent the denitrosylation or regaining of cathepsin activity in vivo. In foresight, this raises the prospect that drugs or novel compounds that target cathepsins taking all these factors into consideration could be deployed as alternative or even better treatments for cancer, though further research is needed to ascertain the safety, efficiency and effectiveness of this approach.

Selenium as an important factor in various disease states - a review

Selenium (Se) is an element that has a pro-health effect on humans and animals. However, both the deficiency of this element and its excess may prove harmful to the body depending on the chemical form of the selenium, the duration of supplementation, and the human health condition. Many data indicate insufficient coverage of the demand for selenium in humans and animals due to its low content in soils and food products. A balance in the physiological process of the body can be achieved via the proper percentage of organically active minerals in the feed of animals as well as human beings. Selenium is a trace mineral of great importance to the body, required for the maintenance of a variety of its processes; primarily, selenium maintains immune endocrine, metabolic, and cellular homeostasis. Recently, this element has been emerging as a most promising treatment option for various disorders. Therefore, research based on Se has been increasing in recent times. The present review is designed to provide up-to-date information related to Se and its different forms as well as its effects on health.

Targeting thioredoxin reductase by micheliolide contributes to radiosensitizing and inducing apoptosis of HeLa cells

Inhibition of thioredoxin reductase (TrxR) is a crucial strategy for the discovery of antineoplastic drugs and radiosensitizers. As an anticancer candidate derived from Michelia, micheliolide (MCL) is converted readily from parthenolide (PTL), and has better stability and solubility than PTL. However, the anticancer mechanism of MCL has not been fully dissected. We present here for the first time that MCL-targeted inhibition of TrxR not only promotes oxidative stress-mediated HeLa cell apoptosis but also sensitizes ionizing radiation (IR) treatment. Further mechanistic studies demonstrate that MCL covalently binds to Sec at position 498 of TrxR to restrain the biological function of TrxR. It exhibits the inhibition of TrxR activity, enhancement of oxidized Trx, and sensitization of IR in the cellular environment, accompanied by the accumulation of reactive oxygen species (ROS) and the collapse of the intracellular redox balance. In addition, HeLa-shTrxR1 cells with knockdown of TrxR were more sensitive than the HeLa-shNT cells to either MCL-treated or IR-induced cytotoxicity, ROS, and apoptosis, suggesting that inhibition of TrxR by MCL is likely responsible for increased cytotoxicity and enhanced radiation response. These findings further establish the mechanistic understanding and preclinical data to support the further investigation of MCL's potential as a prospective radiosensitizer and cancer chemotherapeutic agent.

Novel strategies for targeting the thioredoxin system for cancer therapy

INTRODUCTION

: The thioredoxin system is increasingly recognized as an important executor for maintaining cell redox homeostasis and regulating multiple cell signaling pathways. Targeting this system for cancer treatment has therefore attracted much attention.

AREAS COVERED

: The authors focus on providing coverage and emphasizing the strategy of targeting the thioredoxin system to develop anticancer therapeutics in the past five years, especially from the perspective of discovering novel protein functions or new downstream regulatory pathways, and designing new therapeutic reagents. The authors also provide the readers with their expert perspectives for future development.

EXPERT OPINION

: The limited pharmacophore of inhibitors and the slow progress of clinical research partially restrict the development of anticancer drugs targeting the thioredoxin system, necessitating thus novel strategies to accelerate the system for treating cancer. Nevertheless, the synergistic targeting of thioredoxin system for cancer therapy is a promising strategy, particularly with regards to chemotherapy resistance and/or sensitization immunotherapy.

Inhibition of thioredoxin reductase by natural anticancer candidate β-lapachone accounts for triggering redox activation-mediated HL-60 cell apoptosis

β-Lapachone as a natural novel anticancer candidate is under clinical trials. Previous studies suggested that β-lapachone works by redox activation to ablate cancer cells. However, it is still unclear whether thioredoxin reductase (TrxR), one of the key redox catalytic enzymes in cells, plays a role in the pharmacological effects of β-lapachone. Herein, we present that β-lapachone kills human promyelocytic leukemia HL-60 cells with preference over other cancer cells and normal cells. The follow-up studies demonstrate that β-lapachone induces the HL-60 cell apoptosis through inhibition of TrxR and further elevation of oxidative stress. Overexpression of the TrxR alleviates the efficiency of β-lapachone while knockdown of the enzyme increases the β-lapachone cytotoxicity, scientifically underpinning the correlation of the observed biological behaviors of β-lapachone to TrxR inhibition. The disclosure of the novel action mechanism of β-lapachone sheds light on understanding its capacity in interfering with cellular redox signaling and supports β-lapachone as an anticancer drug candidate.

Natural diterpenoid eriocalyxin B covalently modifies glutathione and selectively inhibits thioredoxin reductase inducing potent oxidative stress-mediated apoptosis in colorectal carcinoma RKO cells

Increasing evidence suggests the significant contribution of high levels of thioredoxin reductase (TrxR) in various stages of tumorigenesis and resistance to tumor chemotherapy. Thus, inhibition of TrxR with small molecules is an attractive strategy for cancer therapy. Eriocalyxin B (EriB), a naturally occurring diterpenoid extracted from Isodon eriocalyx, has reflected potential anticancer activities through numerous pathways. Here, we describe that EriB covalently modifies GSH and selectively inhibits TrxR activity by targeting the Sec residue of the enzyme. Pharmacological inhibition of TrxR by EriB results in elevated ROS levels, reduced total GSH and thiols content, which ultimately induced potent RKO cell apoptosis mediated by oxidative stress. Importantly, EriB indicates potent synthetic lethality with GSH inhibitors, BSO, in RKO cells. In summary, our results highlight that targeting TrxR by EriB explores a novel mechanism for the biological action of EriB. This opened up a new therapeutic indication for using EriB to combat cancers.

Apremilast mitigates interleukin (IL)-13-induced inflammatory response and mucin production in human nasal epithelial cells (hNECs)

Interleukin (IL)-13-associated inflammatory response is important for the pathogenesis of allergic rhinitis (AR). Apremilast is a phosphodiesterase-4 (PDE4) inhibitor approved for psoriasis treatment. Here, we investigated the potential effects of Apremilast against IL-13-induced injury in human nasal epithelial cells (hNECs). Firstly, Apremilast ameliorated oxidative stress in IL-13-challenged cells by decreasing the levels of reactive oxygen species (ROS) and the production of malondialdehyde (MDA). Secondly, Apremilast inhibited the expressions of IL-6 and IL-8. Moreover, Apremilast inhibited the expressions of the chemokines colony-stimulating factor 2 (CSF2) and chemokine ligand 11 (CCL11). Interestingly, exposure to IL-13 increased the expressions of mucin 4 and mucin 5AC (MUC5AC), which was ameliorated by treatment with Apremilast. Interestingly, we found that Apremilast inhibited the phosphorylation of c-Jun-N-terminal kinase (JNK). Importantly, Apremilast reduced the levels of c-fos and c-Jun, the two AP-1 subfamilies. The luciferase reporter assay demonstrates that Apremilast reduced the transcriptional activity of activator protein 1 (AP-1). Lastly, we found that Apremilast prevented the activation of nuclear factor kappa-B (NF-κB) by decreasing the levels of nuclear NF-κB p65 and the luciferase activity of the NF-κB reporter. In summary, we conclude that Apremilast possesses a protective effect against IL-13-induced inflammatory response and mucin production in hNECs by inhibiting the activity of AP-1 and NF-κB.

Inhibition of Thioredoxin Reductase by Santamarine Conferring Anticancer Effect in HeLa Cells

Natural products frequently have unique physiological activities and new action mechanisms due to their structural diversity and novelty, and are an important source for innovative drugs and lead compounds. We present herein that natural product santamarine targeted thioredoxin reductase (TrxR) to weaken its antioxidative function in cells, accompanied by accumulation of high levels of reactive oxygen species (ROS), and finally induced a new mechanism of tumor cell oxidative stress-mediated apoptosis. TrxR knockdown or overexpression cell lines were employed to further evaluate the cytotoxicity of santamarine regulated by TrxR, demonstrated that TrxR played a key role in the physiological effect of santamarine on cells. Santamarine targeting TrxR reveals its previously unrecognized mechanism of antitumor and provides a basis for the further development of santamarine as a potential cancer therapeutic agent.