Cysteine metabolic circuitries: druggable targets in cancer

Cancer stem cells amino acid metabolism: Roles, mechanisms, and intervention strategies

Cancer stem cells (CSCs) are recognized as key drivers of tumor recurrence and therapy resistance due to their capacity for self-renewal and differentiation. Amino acid metabolic reprogramming, a hallmark of cancer, underpins CSC biology. Methionine, tryptophan, and glutamine support CSC survival and the maintenance of stemness, while proline plays a role in CSC differentiation and susceptibility to cell death. Consequently, the impact of amino acid metabolism on CSCs is multifaceted and complex. This review first outlines the intrinsic amino acid metabolic features of CSCs. It then provides a comprehensive analysis of the distinct roles of various amino acids in regulating CSC biology. Additionally, strategies targeting amino acid metabolism to eliminate CSCs in clinical therapies are discussed, offering new perspectives for the development of innovative tumor-targeting approaches.

A near-infrared fluorescent probe selectively recognizing cysteine to release H2S and its applications

Cysteine, a pivotal biothiol vital for human health, exhibits strong associations with various diseases, yet its concentration assessment is often confounded by structurally and functionally similar biothiols. Hydrogen sulfide (H2S), an endogenous gasotransmitter with therapeutic potential, faces challenges in achieving pharmacological effects due to the unpredictable presence of inorganic H2S donors. To address these issues, we developed TMN-ONCS, a near-infrared fluorescent probe that integrates a p-tolyl isothiocyanate with a dicyanoisophorone fluorophore through a self-immolative spacer. TMN-ONCS demonstrates high selectivity and analytical performance for cysteine, avoids the generation of multiple fluorophores seen in conventional isothiocyanate probes, and functions as a cysteine-activated fluorescent H2S donor with concurrent visualization. Furthermore, it mitigates lipopolysaccharide-induced inflammation in RAW 264.7 cells, highlighting its potential for treating inflammation.

The neuroprotective effects of N-acetylcysteine in psychiatric and neurodegenerative disorders: From modulation of glutamatergic transmission to restoration of synaptic plasticity

N-acetylcysteine (NAC) is an effective pleiotropic drug with a strong safety profile. It is predominantly used as a mucolytic agent and in the treatment of paracetamol overdose. However, extensive research in the last decade has shown the prominent efficacy of NAC in many neuropsychiatric and neurodegenerative disorders. NAC acts through multiple mechanisms; primarily, it releases cysteine and modulates glutamatergic and monoaminergic transmission. Further, it restores glutathione levels, promotes oxidative balance, reverses decreased synaptic plasticity, reduces neuroinflammation and mitochondrial dysfunction, and provides neurotrophic support. Additionally, it regulates one-carbon metabolism pathways, leading to the production of key metabolites. In this review, we will be discussing in-depth mechanisms of action of NAC and its promising ability to reverse neuropathological changes, particularly cognitive deficits, and associated plasticity changes in various psychiatric and neurodegenerative diseases, including depression, bipolar disorders, schizophrenia, Alzheimer's disease, Huntington's disease, traumatic brain injury, aging. Overall, several preclinical studies and clinical trials have demonstrated the efficacy of NAC in reversing regressive plasticity, cognitive deficits, and associated changes in the brain. NAC remains among the strongest candidates with a high safety profile for managing several types of neurological disorders.

Salivary Zinc and Copper Levels Are Differentially Associated with ROS Levels in Breast Cancer Patients

Disruption of the balanced metabolism of copper and zinc can be both a consequence and potential cause-trigger for the occurrence of many pathological conditions including cancer. Zinc is an important cofactor of many enzymes that participate in inflammatory and redox reactions and the immune response, and refers to the components of DNA transcription factors. Copper plays an important role in processes such as cuproplasia and cuproptosis, affecting the process of cell differentiation and the epithelial-mesenchymal transition of cancer cells. In this regard, the study of changes in copper and zinc in breast cancer can provide valuable information on the metabolic features of cancer cells. In this study, we investigated the metabolic relationship between the zinc and copper levels in the saliva of patients with breast cancer and the content of reactive oxygen species, the state of the antioxidant and immune systems as well as the metabolism of the amino acids Cys, His, Met, and Arg. We also considered how the content and ratio of copper and zinc in saliva changes in patients with breast cancer depend on the state of the hormonal background and the expression of hormone receptors.

Unraveled cancer cell survival-associated amino acid metabolism of HepG2 cells altered by Thai rat-tailed radish microgreen extract examined by untargeted LC-MS/MS analysis

Thai rat-tailed radish (RS) microgreens are enriched in macro- and micronutrients and phytochemicals with anticancer potential. This study investigates the antiproliferative effects of RS in the liver HepG2 cell model and untargeted liquid chromatography-mass spectrometry (LC-MS) metabolomics analysis. RS was partitioned in water and dichloromethane (DCM). DCM was collected and evaporated to yield crude extract. The extract exhibited antiproliferation with inhibitory concentrations (IC50) of 612.5 ± 24.7 μg/ml at 24 h and 568.6 ± 11.0 μg/ml at 48 h. Metabolic pathways relevant to the anticancer effects are amino acid metabolism, including (1) alanine, aspartate, and glutamate metabolism; (2) nicotinate and nicotinamide metabolism; and (3) cysteine and methionine metabolism. Significantly, glutamine was upregulated, and aspartic acid, NAD, 5'-methylthioadenosine, cystathionine, and S-adenosylhomocysteine were downregulated. This finding suggested plausible effects of RS on liver cancer cell survival and invasion activities.

Design, optimization, and ADMET evaluation of S11a-0000168202: A promising LIMK1 inhibitor for gastric cancer treatment

This study focuses on the development and optimization of S11a-0000168202, a novel LIMK1 inhibitor with potential therapeutic applications in gastric cancer. Through scaffold hopping and structural modification of HIT100844099, S11a-0000168202 demonstrated enhanced binding stability and stronger interactions with key LIMK1 residues, including GLU-414, ILE-416, and HIS-464. Molecular dynamics simulations and MMGBSA analyses confirmed the compound's stability, while ADMET evaluation revealed favorable properties such as moderate lipophilicity, good human intestinal absorption, and low P-glycoprotein inhibition. Despite the promising computational results, the lack of experimental validation remains a limitation. Future studies should focus on in vitro and in vivo testing to confirm S11a-0000168202's efficacy, pharmacokinetics, and safety. This compound holds significant potential as a therapeutic agent for LIMK1-targeted gastric cancer treatment.

Single-cell and multi-omics integration reveals cholesterol biosynthesis as a synergistic target with HER2 in aggressive breast cancer

Breast cancer stands as one of the most prevalent malignancies affecting women. Alterations in molecular pathways in cancer cells represent key regulatory disruptions that drive malignancy, influencing cancer cell survival, proliferation, and potentially modulating therapeutic responsiveness. Therefore, decoding the intricate molecular mechanisms and identifying novel therapeutic targets through systematic computational approaches are essential steps toward advancing effective breast cancer treatments. In this study, we developed an integrative computational framework that combines single-cell RNA sequencing (scRNA-seq) and multi-omics analyses to delineate the functional characteristics of malignant cell subsets in breast cancer patients. Our analyses revealed a significant correlation between cholesterol biosynthesis and HER2 expression in malignant breast cancer cells, supported by proteomics data, gene expression profiles, drug treatment scores, and cell-surface HER2 intensity measurements. Given previous evidence linking cholesterol biosynthesis to HER2 membrane dynamics, we proposed a combinatorial strategy targeting both pathways. Experimental validation through clonogenic and viability assays demonstrated that simultaneous inhibition of cholesterol biosynthesis (via statins) and HER2 (via Neratinib) synergistically reduced malignant breast cancer cells, even in HER2-negative contexts. Through systematic analysis of scRNA-seq and multi-omics data, our study computationally identified and experimentally validated cholesterol biosynthesis and HER2 as novel combinatorial therapeutic targets in breast cancer. This data-driven approach highlights the potential of leveraging multiple molecular profiling techniques to uncover previously unexplored treatment strategies.

CDO1 phosphorylation is required for IL-6-induced tumor cell proliferation through governing cysteine availability

Inflammatory pathways are often hijacked by cancer cells to favor their own proliferation and survival. Cysteine dioxygenase type 1 (CDO1), an iron-dependent thiol dioxygenase enzyme, catalyzes the rate-limiting step for cysteine oxidation, and so that functions as an important regulator of cellular cysteine availability. However, whether inflammatory environment affects CDO1 activity and cysteine oxidation and its potential impact on tumor growth remains substantially elusive. In the present study, we demonstrate that CDO1 activity and cysteine oxidation is inhibited upon IL-6 treatment, without noticeable alterations in CDO1 expression. Mechanistically, AKT1 phosphorylates CDO1 T89 under IL-6 treatment, which represses CDO1 enzymatic activity by disrupting iron incorporation. Further, AKT1-mediated CDO1 T89 phosphorylation is required for IL-6-elicited oral squamous cell carcinoma (OSCC) growth, and is associated with the progression of OSCC development. The present data discover a new mechanism by which AKT1-mediated CDO1 T89 phosphorylation governs cysteine oxidation to support OSCC growth, thereby highlighting its value as a potential anti-tumor target.

Deep sequencing reveals distinct microRNA-mRNA signatures that differentiate pancreatic neuroendocrine tumor from non-diseased pancreas tissue

BACKGROUND

Only a limited number of biomarkers guide personalized management of pancreatic neuroendocrine tumors (PanNETs). Transcriptome profiling of microRNA (miRs) and mRNA has shown value in segregating PanNETs and identifying patients more likely to respond to treatment. Because miRs are key regulators of mRNA expression, we sought to integrate expression data from both RNA species into miR-mRNA interaction networks to advance our understanding of PanNET biology.

METHODS

We used deep miR/mRNA sequencing on six low-grade/high-risk, well-differentiated PanNETs compared with seven non-diseased tissues to identify differentially expressed miRs/mRNAs. Then we crossed a list of differentially expressed mRNAs with a list of in silico predicted mRNA targets of the most and least abundant miRs to generate high probability miR-mRNA interaction networks.

RESULTS

Gene ontology and pathway analyses revealed several miR-mRNA pairs implicated in cellular processes and pathways suggesting perturbed neuroendocrine function (miR-7 and Reg family genes), cell adhesion (miR-216 family and NLGN1, NCAM1, and CNTN1; miR-670 and the claudins, CLDN1 and CLDN2), and metabolic processes (miR-670 and BCAT1/MPST; miR-129 and CTH).

CONCLUSION

These novel miR-mRNA interaction networks identified dysregulated pathways not observed when assessing mRNA alone and provide a foundation for further investigation of their utility as diagnostic and predictive biomarkers.

Adaptation mechanisms in cancer: Lipid metabolism under hypoxia and nutrient deprivation as a target for novel therapeutic strategies (Review)

Tumor tissues generally exist in a relatively hypovascular state, and cancer cells must adapt to severe tissue conditions with a limited molecular oxygen and nutrient supply for their survival. Lipid metabolism serves a role in this adaptation. Lipids are supplied not only through the bloodstream but also through autonomous synthesis by cancer cells, and they function as sources of adenosine triphosphate and cell components. Although cancer‑associated lipid metabolism has been widely reviewed, how this metabolism responds to the tumor environment with poor molecular oxygen and nutrient supply remains to be fully discussed. The main aim of the present review was to summarize the findings on this issue and to provide insights into how cancer cells adapt to better cope with metabolic stresses within tumors. It may be suggested that diverse types of lipid metabolism have a role in enabling cancer cells to adapt to both hypoxia and nutrient‑poor conditions. Gaining a deeper understanding of these molecular mechanisms may reveal novel possibilities of exploration for cancer treatment.

Role of the sulfur-containing amino acid-ROS axis in cancer chemotherapeutic drug resistance

Chemotherapeutic drug resistance remains a major barrier to effective cancer treatment. Drug resistance could be driven in part by adaptive redox remodeling of cancer cells. Paradoxically, drug-resistant malignancies exhibit elevated reactive oxygen species (ROS), as well as amplified antioxidant defenses, which enable cancer cell survival under therapeutic stress. Central to this adaptation is glutathione (GSH), the predominant cellular antioxidant, whose synthesis relies on sulfur-containing amino acids (SAAs) - methionine and cysteine. This review delineates the metabolic interplay between methionine and cysteine in the transsulfuration pathway, highlighting their roles as precursors in GSH biosynthesis. We systematically summarize the key enzymes that drive GSH production and their contributions to resistance against platinum-based drugs and other chemotherapeutics. In addition to GSH synthesis, we summarize the roles of GSH antioxidant systems, including glutathione peroxidases (GPXs), peroxiredoxins (PRDXs), and thioredoxins (TRXs), which are critical in chemotherapeutic drug resistance through ROS scavenging. Recent advances reveal that targeting these enzymes, by pharmacologically inhibiting transsulfuration enzymes or disrupting GSH-dependent antioxidant cascades, can sensitize resistant cancer cells to ROS-mediated therapies. These findings not only clarify the mechanistic links between SAA metabolism and redox adaptation but also provide practical approaches to overcome chemotherapeutic drug resistance. By analyzing metabolic and redox vulnerabilities, this review highlights the therapeutic potential to restore chemosensitivity, offering new options in precision oncology medicine.

Exploring Mechanisms and Biomarkers of Breast Cancer Invasion and Migration: An Explainable Gene-Pathway-Compounds Neural Network

BACKGROUNDS

Exploring the molecular features that drive breast cancer invasion and migration remains an important biological and clinical challenge. In recent years, the use of interpretable machine learning models has enhanced our understanding of the underlying mechanisms of disease progression.

METHODS

In this study, we present a novel gene-pathway-compound-related sparse deep neural network (GPC-Net) for investigating breast cancer invasion and migration. The GPC-Net is an interpretable neural network model that utilizes molecular data to predict cancer status. It visually represents genes, pathways, and associated compounds involved in these pathways.

RESULTS

Compared with other modeling methods, GPC-Net demonstrates superior performance. Our research identifies key genes, such as ADCY8, associated with invasive breast cancer and verifies their expression in breast cancer cells. In addition, we conducted a preliminary exploration of several pathways.

CONCLUSION

GPC-Net is among the pioneering deep neural networks that incorporate pathways and compounds, aiming to balance interpretability and performance. It is expected to offer a more convenient approach for future biomedical research.

Evaluating the effects of zinc oxide nanoparticles on a sentinel aquatic invertebrate species: Transcriptomic analysis and potential implications for ecosystem health

The widespread use of zinc oxide nanoparticles (ZnO NPs) in various products raises significant ecological concerns due to their potential toxic effects in aquatic environments. This study employed the Asian green mussel (Perna viridis) as a model to explore the molecular and ecological risks of ZnO NP exposure using transcriptomics. Mussels exposed to ZnO NPs (5, 10, and 15 mg/L) for 28 days showed significant gene expression changes in gill tissues, affecting immune response, calcium homeostasis, and cellular stress. Disrupted pathways such as FOXO, Wnt, and TGFβ reveal complex toxicity mechanisms. These findings provide crucial insights into the environmental impact of nanoparticle pollution, emphasizing the need for stringent regulations. Furthermore, the shared molecular pathways suggest that similar mechanisms may occur in humans, highlighting potential health risks associated with nanoparticle exposure.

Nanomaterial-Triggered Ferroptosis and Cuproptosis in Cancer Therapy

Cancer remains one of the leading causes of the death of individuals globally. Conventional treatment techniques like chemotherapy and radiation often suffer various drawbacks like toxicity and drug resistance. The study of cell death has been predominantly focused on classical forms like apoptosis, but the role of metal ions in governing controlled cell death is a fascinating and less explored area. Metal-mediated controlled cell death is a process where metal triggers cell death via a unique mechanism. Nanomaterial-based strategies have gained attention for their ability to deliver precise therapeutic agents while also triggering Regulated Cell Death (RCD) mechanisms in cancer cells. The recently discovered metal-mediated controlled cell death techniques like cuproptosis and ferroptosis can be used in cancer treatment as they can be used selectively for the treatment of drug-resistant cancer. Nano material-based delivery system can also be used for the precise delivery of the drug to the targeted sites. In this review, we have given some idea about the mechanism of metal-mediated controlled cell death techniques (ferroptosis and cuproptosis) and how we can initiate controlled cell deaths using nanomaterials for cancer treatment.

The impact of cysteine on lifespan in three model organisms: A systematic review and meta-analysis

Cysteine is an amino acid present in thiol proteins and often dictates their secondary structures. Although considered nonessential, cysteine may be essential for patients with certain metabolic diseases and can reduce the requirement for dietary methionine. Cysteine and some of its derivatives, such as N-acetylcysteine, are considered antioxidants and widely used in animal aging studies. To provide insights into the potential anti-aging effects of cysteine, we systematically reviewed and performed a meta-analysis to investigate the impact of cysteine supplementation on lifespan using three model organisms: mice, nematodes, and fruit flies. A total of 13 mouse studies, 13 C. elegans studies, and 5 Drosophila studies were included in the analysis. The findings revealed that cysteine supplementation significantly reduced the risk of mortality in mice and C. elegans. Subgroup analysis showed consistent results across different starting times and administration methods and revealed adverse effects of high doses on worms and a lack of effect in nondisease mouse models. Similar to mice, the effects of cysteine supplementation on Drosophila were not statistically significant, except in transgenic flies. The study identified certain limitations, including the quality of the included studies and the potential for publication bias. We also discussed uncertainties in the underlying molecular mechanisms and the clinical application of dietary cysteine.

On-Off-On Fluorometric Detection of Hg(II) and L-Cysteine Using Red Emissive Nitrogen-Doped Carbon Dots for Environmental and Clinical Sample Analysis

This research introduces a novel fluorescence sensor 'on-off-on' employing nitrogen-doped carbon dots (N-CDs) with an 'on-off-on' mechanism for the selective and sensitive detection of Hg(II) and L-cysteine (L-Cys). N-CDs was synthesized using citric acid as the carbon precursor and urea as the nitrogen source in dimethylformamide (DMF) solvent, resulting in red emissive characteristics under UV light. Comprehensive spectroscopic analyses, including UV-Vis, fluorescence, FT-IR, XRD, XPS, Raman, and Zeta potential techniques, validated the structural and optical characteristics of the synthesized N-CDs. The maximum excitation and emission of N-CDs were observed at 548 and 622 nm, respectively. The quantum yield of N-CDs was calculated to be 16.1%. The fluorescence of N-CDs effectively quenches upon the addition of Hg(II) due to the strong coordination between Hg(II) and the surface functionalities of N-CDs. Conversely, upon the subsequent addition of L-Cys, the fluorescence of N-CDs was restored. This restoration can be attributed to the stronger affinity of the -SH group in L-Cys towards Hg(II) relative to the surface functionalities of N-CDs. This dual-mode response enabled the detection of Hg(II) and L-Cys with impressive detection limits of 15.1 nM and 8.0 nM, respectively. This sensor methodology effectively detects Hg(II) in lake water samples and L-Cys levels in human urine, with a recovery range between 99 and 101%. Furthermore, the N-CDs demonstrated excellent stability, high sensitivity, and selectivity, making them a promising fluorescence on-off-on probe for both environmental monitoring of Hg(II) and clinical diagnostics of L-Cys.

Fluorous-Phase- and Chiral-Axis-Enhanced Fluorescent Sensitivity and Chemoselectivity for Cysteine Recognition

Highly fluorinated naphthyl aldehyde 1 and binaphthyl aldehyde (R)-2 were designed and synthesized for fluorous-phase-based sensing. Greatly enhanced sensitivity and chemoselectivity in going from 1 to (R)-2 in the fluorescent detection of cysteine has been discovered. This is attributed to the increased structural rigidity of the axially chiral binaphthyl unit in (R)-2 upon reaction with cysteine to form the corresponding thiazolidine product. The fluorous-phase-based detection of cysteine not only can allow the analysis to be conducted in a phase away from the interference of other organic and inorganic species but also results in significantly increased fluorescence response.

Evaluating the performance of multi-omics integration: a thyroid toxicity case study

Multi-omics data integration has been repeatedly discussed as the way forward to more comprehensively cover the molecular responses of cells or organisms to chemical exposure in systems toxicology and regulatory risk assessment. In Canzler et al. (Arch Toxicol 94(2):371-388. https://doi.org/10.1007/s00204-020-02656-y ), we reviewed the state of the art in applying multi-omics approaches in toxicological research and chemical risk assessment. We developed best practices for the experimental design of multi-omics studies, omics data acquisition, and subsequent omics data integration. We found that multi-omics data sets for toxicological research questions were generally rare, with no data sets comprising more than two omics layers adhering to these best practices. Due to these limitations, we could not fully assess the benefits of different data integration approaches or quantitatively evaluate the contribution of various omics layers for toxicological research questions. Here, we report on a multi-omics study on thyroid toxicity that we conducted in compliance with these best practices. We induced direct and indirect thyroid toxicity through Propylthiouracil (PTU) and Phenytoin, respectively, in a 28-day plus 14-day recovery oral rat toxicity study. We collected clinical and histopathological data and six omics layers, including the long and short transcriptome, proteome, phosphoproteome, and metabolome from plasma, thyroid, and liver. We demonstrate that the multi-omics approach is superior to single-omics in detecting responses at the regulatory pathway level. We also show how combining omics data with clinical and histopathological parameters facilitates the interpretation of the data. Furthermore, we illustrate how multi-omics integration can hint at the involvement of non-coding RNAs in post-transcriptional regulation. Also, we show that multi-omics facilitates grouping, and we assess how much information individual and combinations of omics layers contribute to this approach.

Lactate/Cysteine Dual-Consuming Probiotic-Nanomedicine Biohybrid System for Enhanced Cancer Chemo-Immunotherapy

Immunotherapy is revolutionizing oncology, but its therapeutic efficiency is still limited by the off-target toxicities and poor antitumor immune responses. By integrating the drug-loaded nanoparticles (DMnSH) with the unique metabolic traits of Veillonella parvula (Vei), a probiotic-nanomedicine conjugate Vei@DMnSH biohybrid is elaborately designed for enhanced cancer chemo-immunotherapy. Specifically, Vei@DMnSH can accumulate in hypoxic tumor sites and simultaneously consume lactate and cysteine to reverse the lactate-associated immunosuppression and impede the biosynthesis of GSH. In addition, the DMnSH nanoparticles will rapidly deplete intracellular GSH and disassemble to release DOX and Mn2+. Accompanied by the two-pronged GSH depletion, the Mn2+-mediated Fenton-like reaction can effectively generate oxidative hydroxyl radicals to induce heavy redox imbalance. Combined with the therapeutic effect of DOX, robust immunogenic cell death is provoked and subsequently activates antitumor adaptive immunity with a tumor suppression rate over 82%, synergistically enhancing the therapeutic outcomes of cancer chemo-immunotherapy.

The role of cystathionine β-synthase in cancer

Cystathionine β-synthase (CBS) occupies a key position as the initiating and rate-limiting enzyme in the sulfur transfer pathway and plays a vital role in health and disease. CBS is responsible for regulating the metabolism of cysteine, the precursor of glutathione (GSH), an important antioxidant in the body. Additionally, CBS is one of the three enzymes that produce hydrogen sulfide (H2S) in mammals through a variety of mechanisms. The dysregulation of CBS expression in cancer cells affects H2S production through direct or indirect pathways, thereby influencing cancer growth and metastasis by inducing angiogenesis, facilitating proliferation, migration, and invasion, modulating cellular energy metabolism, promoting cell cycle progression, and inhibiting apoptosis. It is noteworthy that CBS expression exhibits complex changes in different cancer models. In this paper, we focus on the CBS synthesis and metabolism, tissue distribution, potential mechanisms influencing tumor growth, and relevant signaling pathways. We also discuss the impact of pharmacological CBS inhibitors and silencing CBS in preclinical cancer models, supporting their potential as targeted cancer therapies.

Emerging roles of hydrogen sulfide-metabolizing enzymes in cancer

Gasotransmitters play crucial roles in regulating many physiological processes, including cell signaling, cellular proliferation, angiogenesis, mitochondrial function, antioxidant production, nervous system functions and immune responses. Hydrogen sulfide (H2S) is the most recently identified gasotransmitter, which is characterized by its biphasic behavior. At low concentrations, H2S promotes cellular bioenergetics, whereas at high concentrations, it can exert cytotoxic effects. Cystathionine β-synthetase (CBS), cystathionine-γ-lyase (CSE), 3-mercaptopyruvate sulfurtransferase (3-MST), and cysteinyl-tRNA synthetase 2 (CARS2) are pivotal players in H2S biosynthesis in mammalian cells and tissues. The focus of this review is the regulation of the various pathways involved in H2S metabolism in various forms of cancer. Key enzymes in this process include the sulfide oxidation unit (SOU), which includes sulfide:quinone oxidoreductase (SQOR), human ethylmalonic encephalopathy protein 1 (hETHE1), rhodanese, sulfite oxidase (SUOX/SO), and cytochrome c oxidase (CcO) enzymes. Furthermore, the potential role of H2S methylation processes mediated by thiol S-methyltransferase (TMT) and thioether S-methyltransferase (TEMT) is outlined in cancer biology, with potential opportunities for targeting them for clinical translation. In order to understand the role of H2S in oncogenesis and tumor progression, one must appreciate the intricate interplay between H2S-synthesizing and H2S-catabolizing enzymes.

Alterations in Glutathione Redox Homeostasis in Metabolic Dysfunction-Associated Fatty Liver Disease: A Systematic Review

Low molecular weight (LMW) thiols, particularly glutathione, play pathogenic roles in various multiorgan diseases. The liver is central for the production and systemic distribution of LMW thiols; thus, it is particularly susceptible to the imbalance of redox status that may determine increased oxidative stress and trigger the liver damage observed in metabolic dysfunction-associated steatotic liver disease (MASLD) models and humans. Indeed, increased LMW thiols at the cellular and extracellular levels may be associated with the severity of MASLD. Here, we present a systematic literature review of recent studies assessing the levels of LMW thiols in MASLD in in vivo and in vitro models and human subjects. Based on the PRISMA 2020 criteria, a search was conducted using PubMed and Scopus by applying inclusion/exclusion filters. The initial search returned 1012 documents, from which 165 eligible studies were selected, further described, and qualitatively analysed. Of these studies, most focused on animal and cellular models, while a minority used human fluids. The analysis of these studies revealed heterogeneity in the methods of sample processing and measurement of LMW thiol levels, which hinder cut-off values for diagnostic use. Standardisation of the analysis and measure of LMW thiol is necessary to facilitate future studies.

Integration of epigenomic and transcriptomic profiling uncovers EZH2 target genes linked to cysteine metabolism in hepatocellular carcinoma

Enhancer of zeste homolog 2 (EZH2), a key protein implicated in various cancers including hepatocellular carcinoma (HCC), is recognized for its association with epigenetic dysregulation and pathogenesis. Despite clinical explorations into EZH2-targeting therapies, the mechanisms underlying its role in gene suppression in HCC have remained largely unexplored. Here, we integrate epigenomic and transcriptomic analyses to uncover the transcriptional landscape modulated by selective EZH2 inhibition in HCC. By reanalyzing transcriptomic data of HCC patients, we demonstrate that EZH2 overexpression correlates with poor patient survival. Treatment with the EZH2 inhibitor tazemetostat restored expression of genes involved in cysteine-methionine metabolism and lipid homeostasis, while suppressing angiogenesis and oxidative stress-related genes. Mechanistically, we demonstrate EZH2-mediated H3K27me3 enrichment at cis-regulatory elements of transsulfuration pathway genes, which is reversed upon inhibition, leading to increased chromatin accessibility. Among 16 EZH2-targeted candidate genes, BHMT and CDO1 were notably correlated with poor HCC prognosis. Tazemetostat treatment of HCC cells increased BHMT and CDO1 expression while reducing levels of ferroptosis markers FSP1, NFS1, and SLC7A11. Functionally, EZH2 inhibition dose-dependently reduced cell viability and increased lipid peroxidation in HCC cells. Our findings reveal a novel epigenetic mechanism controlling lipid peroxidation and ferroptosis susceptibility in HCC, providing a rationale for exploring EZH2-targeted therapies in this malignancy.

SLC7A9 suppression increases chemosensitivity by inducing ferroptosis via the inhibition of cystine transport in gastric cancer

BACKGROUND

SLC7A9 is responsible for the exchange of dibasic amino acids and cystine (influx) for neutral amino acids (efflux). Cystine/cysteine transport is related to ferroptosis.

METHODS

Sanger sequencing detected TP53 status of cancer cells. Transcriptomic sequencing and untargeted metabolome profiling were used to identify differentially expressed genes and metabolites, respectively, upon SLC7A9 overexpression. CCK8, cell clonality, and EdU assays were used to observe cell proliferation. Cystine probes, glutathione (GSH) probes, and lipid ROS probes were used to examine cystine, GSH, and lipid ROS levels. 13C metabolic flow assays were used to monitor cellular cystine and GSH metabolism. Patient-derived organoids (PDO), immunocompetent MFC mice allograft models and patient-derived xenograft (PDX) models were used to evaluate SLC7A9 impact on chemotherapeutic response and to observe therapeutic effect of SLC7A9 knockdown.

FINDINGS

Elevated SLC7A9 expression levels in gastric cancer cells were attributed to p53 loss. SLC7A9 knockdown suppressed the proliferation and increased the chemotherapy sensitivity of the cells. Chemotherapy was more effective in PDX and immunocompetent mice models upon SLC7A9 knockdown. Differentially expressed genes and metabolites between the SLC7A9 overexpression and control groups were associated with ferroptosis and GSH metabolism. SLC7A9 knockdown reduced cystine transport into cells, hampered intracellular cystine and GSH metabolic flow, decreased GSH synthesis, and increased lipid ROS levels in gastric cancer cells. Erastin was more effective at inducing ferroptosis in PDO and PDX models upon SLC7A9 knockdown.

INTERPRETATION

SLC7A9 promotes gastric cancer progression by acting as a suppressor of ferroptosis, independent of SLC7A11, which is negatively regulated by p53.

FUNDING

This work was supported by National Natural Science Foundation of China, Innovation Promotion Program of NHC and Shanghai Key Labs SIBPT, and Shanghai Academy of Science & Technology.

Oncogenic accumulation of cysteine promotes cancer cell proliferation by regulating the translation of D-type cyclins

Malignant cells exhibit a high demand for amino acids to sustain their abnormal proliferation. Particularly, the intracellular accumulation of cysteine is often observed in cancer cells. Previous studies have shown that deprivation of intracellular cysteine in cancer cells results in the accumulation of lipid peroxides in the plasma membrane and induction of ferroptotic cell death, indicating that cysteine plays a critical role in the suppression of ferroptosis. Herein, we found that the oncogenic accumulation of cysteine also contributes to cancer cell proliferation by promoting the cell cycle progression, which is independent of its suppressive effect on ferroptosis. The growth ability of four types of cancer cells, including murine hepatocarcinoma cells, but not of primary hepatocytes, were dependent on the exogenous supply of cysteine. Deprivation of intracellular cysteine in cancer cells induced cell cycle arrest at the G0/G1 phase, accompanied by a decrease in the expression of cyclin D1 and D2 proteins. The cysteine deprivation-induced decrease in D-type cyclin expression was associated with the upregulation of eukaryotic translation initiation factor 4E binding protein 1, which represses the translation of cyclin D1 and D2 proteins by binding to eukaryotic translation initiation factor 4E. Similar results were observed in hepatocarcinoma cells treated with erastin, an inhibitor of cystine/glutamate antiporter, xCT. These findings reveal an unappreciated role of cysteine in regulating the growth of malignant cancer cells and deepen our understanding of the cytotoxic effect of xCT inhibitor to prevent cancer cell proliferation.

Cysteamine dioxygenase (ADO) governs cancer cell mitochondrial redox homeostasis through proline metabolism

2-Aminoethanethiol dioxygenase (ADO) is a thiol dioxygenase that sulfinylates cysteamine and amino-terminal cysteines in polypeptides. The pathophysiological roles of ADO remain largely unknown. Here, we demonstrate that ADO expression represents a vulnerability in cancer cells, as ADO depletion led to loss of proliferative capacity and survival in cancer cells and reduced xenograft growth. In contrast, generation of the ADO knockout mouse revealed high tolerance for ADO depletion in adult tissues. To understand the mechanism underlying ADO's essentiality in cancer cells, we characterized the cell proteome and metabolome following depletion of ADO. This revealed that ADO depletion leads to toxic levels of polyamines which can be driven by ADO's substrate cysteamine. Polyamine accumulation in turn stimulated expression of proline dehydrogenase (PRODH) which resulted in mitochondrial hyperactivity and ROS production, culminating in cell toxicity. This work identifies ADO as a unique vulnerability in cancer cells, due to its essential role in maintenance of redox homeostasis through restraining polyamine levels and proline catabolism.

CuO Nanozymes Catalyze Cysteine and Glutathione Depletion Induced Ferroptosis and Cuproptosis for Synergistic Tumor Therapy

The latest research identifies that cysteine (Cys) is one of the key factors in tumor proliferation, metastasis, and recurrence. The direct depletion of intracellular Cys shows a profound antitumor effect. However, using nanozymes to efficiently deplete Cys for tumor therapy has not yet attracted widespread attention. Here, a (3-carboxypropyl) triphenylphosphonium bromide-derived hyaluronic acid-modified copper oxide nanorods (denoted as MitCuOHA) are designed with cysteine oxidase-like, glutathione oxidase-like and peroxidase-like activities to realize Cys depletion and further induce cellular ferroptosis and cuproptosis for synergistic tumor therapy. MitCuOHA nanozymes can efficiently catalyze the depletion of Cys and glutathione (GSH), accompanied by the generation of H2O2 and the subsequent conversion into highly active hydroxyl radicals, thereby successfully inducing ferroptosis in cancer cells. Meanwhile, copper ions released by MitCuOHA under tumor microenvironment stimulation directly bind to lipoylated proteins of the tricarboxylic acid cycle, leading to the abnormal aggregation of lipoylated proteins and subsequent loss of iron-sulfur cluster proteins, which ultimately triggers proteotoxic stress and cell cuproptosis. Both in vitro and in vivo results show the drastically enhanced anticancer efficacy of Cys oxidation catalyzed by the MitCuOHA nanozymes, demonstrating the high feasibility of such catalytic Cys depletion-induced synergistic ferroptosis and cuproptosis therapeutic concept.

The role of nonesterified fatty acids in cancer biology: Focus on tryptophan and related metabolism

Plasma nonesterified fatty acids (NEFA) are elevated in cancer, because of decreased albumin levels and of fatty acid oxidation, and increased fatty acid synthesis and lipolysis. Albumin depletion and NEFA elevation maximally release albumin-bound tryptophan (Trp) and increase its flux down the kynurenine pathway, leading to increased production of proinflammatory kynurenine metabolites, which tumors use to undermine T-cell function and achieve immune escape. Activation of the aryl hydrocarbon receptor by kynurenic acid promotes extrahepatic Trp degradation by indoleamine 2,3-dioxygenase and leads to upregulation of poly (ADP-ribose) polymerase, activation of which and also of SIRT1 (silent mating type information regulation 2 homolog 1) could lead to depletion of NAD+ and ATP, resulting in cell death. NEFA also modulate heme synthesis and degradation, changes in which impact homocysteine metabolism and production of reduced glutathione and hydrogen sulphide. The significance of the interactions between heme and homocysteine metabolism in cancer biology has received little attention. Targeting Trp disposition in cancer to prevent the NEFA effects is suggested.

Cystathionine gamma-lyase deficiency exaggerates diethylnitrosamine-induced liver damage in mice

Cystathionine gamma-lyase (CSE) is a key enzyme in reverse transsulfuration pathway and contributes to the majority of H2S generation in liver tissues via cysteine metabolism. Dysfunction of the CSE/H2S system is linked to both chronic and acute liver damage. This study investigated the regulatory role of CSE deficiency on diethylnitrosamine (DEN)-induced liver damage in mice. A single injection of DEN was administered into 4-week-old male CSE knockout (CSE-KO) mice and wild-type (WT) littermates, and the mice were sacrificed at 28 weeks of age. Compared to age-matched WT mice, CSE-KO mice spontaneously developed steatosis with increased oxidative stress and higher expressions of inflammation and fibrosis-related genes at 28-weeks of age. Following DEN injection, CSE-KO mice experienced more severe liver damage in comparison with the WT group as reflected by elevated levels of lipid accumulation, increased activities of alanine aminotransferase and aspartate aminotransferase, higher oxidative stress and fibrosis development, and increased expressions of inflammation and fibrosis-related genes. No visible tumors were observed in both types of mice with DEN treatment. In addition, the expression levels of the three H2S-generating proteins (CSE, cystathionine beta-synthase, and 3-mercaptopyruvate sulfurtransferase) and the H2S production rate in liver tissues were unaffected by DEN. Taken together, our study demonstrates that CSE provides a significant hepatoprotective effect and deficiency of CSE exaggerates DEN-induced liver damage in mice. Based on these findings, it can be suggested that targeting the CSE/H2S signaling pathway could be a potential therapeutic target for the treatment of liver diseases.

The epigenetic signatures of opioid addiction and physical dependence are prevented by D-cysteine ethyl ester and betaine

We have reported that D,L-thiol esters, including D-cysteine ethyl ester (D-CYSee), are effective at overcoming opioid-induced respiratory depression (OIRD) in rats. Our on-going studies reveal that co-injections of D-CYSee with multi-day morphine injections markedly diminish spontaneous withdrawal that usually occurs after cessation of multiple injections of morphine in rats. Chronically administered opioids are known (1) to alter cellular redox status, thus inducing an oxidative state, and (2) for an overall decrease in DNA methylation, therefore resulting in the transcriptional activation of previously silenced long interspersed elements (LINE-1) retrotransposon genes. The first objective of the present study was to determine whether D-CYSee and the one carbon metabolism with the methyl donor, betaine, would maintain redox control and normal DNA methylation levels in human neuroblastoma cell cultures (SH-SY5Y) under overnight challenge with morphine (100 nM). The second objective was to determine whether D-CYSee and/or betaine could diminish the degree of physical dependence to morphine in male Sprague Dawley rats. Our data showed that overnight treatment with morphine reduced cellular GSH levels, induced mitochondrial damage, decreased global DNA methylation, and increased LINE-1 mRNA expression. These adverse effects by morphine, which diminished the reducing capacity and compromised the maintenance of the membrane potential of SH-SY5Y cells, was prevented by concurrent application of D-CYSee (100 µM) or betaine (300 µM). Furthermore, our data demonstrated that co-injections of D-CYSee (250 μmol/kg, IV) and to a lesser extent, betaine (250 μmol/kg, IV), markedly diminished the development of physical dependence induced by multi-day morphine injections (escalating daily doses of 10-30 mg/kg, IV), as assessed by the lesser number of withdrawal phenomena elicited by the injection of the opioid receptor antagonist, naloxone (1.5 mg/kg, IV). These findings provide evidence that D-CYSee and betaine prevent the appearance of redox alterations and epigenetic signatures commonly seen in neural cells involved in opioid physical dependence/addiction, and lessen development of physical dependence to morphine.

Epigenetic repression of de novo cysteine synthetases induces intra-cellular accumulation of cysteine in hepatocarcinoma by up-regulating the cystine uptake transporter xCT

BACKGROUND

The metabolic reprogramming of amino acids is critical for cancer cell growth and survival. Notably, intracellular accumulation of cysteine is often observed in various cancers, suggesting its potential role in alleviating the oxidative stress associated with rapid proliferation. The liver is the primary organ for cysteine biosynthesis, but much remains unknown about the metabolic alterations of cysteine and their mechanisms in hepatocellular carcinoma cells.

METHODS

RNA-seq data from patients with hepatocarcinoma were analyzed using the TNMplot database. The underlying mechanism of the oncogenic alteration of cysteine metabolism was studied in mice implanted with BNL 1ME A.7 R.1 hepatocarcinoma.

RESULTS

Database analysis of patients with hepatocellular carcinoma revealed that the expression of enzymes involved in de novo cysteine synthesis was down-regulated accompanying with increased expression of the cystine uptake transporter xCT. Similar alterations in gene expression have also been observed in a syngeneic mouse model of hepatocarcinoma. The enhanced expression of DNA methyltransferase in murine hepatocarcinoma cells caused methylation of the upstream regions of cysteine synthesis genes, thereby repressing their expression. Conversely, suppression of de novo cysteine synthesis in healthy liver cells induced xCT expression by up-regulating the oxidative-stress response factor NRF2, indicating that reduced de novo cysteine synthesis repulsively increases cystine uptake via enhanced xCT expression, leading to intracellular cysteine accumulation. Furthermore, the pharmacological inhibition of xCT activity decreased intracellular cysteine levels and suppressed hepatocarcinoma tumor growth in mice.

CONCLUSIONS

Our findings indicate an underlying mechanism of the oncogenic alteration of cysteine metabolism in hepatocarcinoma and highlight the efficacy of alteration of cysteine metabolism as a viable therapeutic target in cancer.

Metabolic profiling and combined therapeutic strategies unveil the cytotoxic potential of selenium-chrysin (SeChry) in NSCLC cells

Lung cancer ranks as the predominant cause of cancer-related mortalities on a global scale. Despite progress in therapeutic interventions, encompassing surgical procedures, radiation, chemotherapy, targeted therapies and immunotherapy, the overall prognosis remains unfavorable. Imbalances in redox equilibrium and disrupted redox signaling, common traits in tumors, play crucial roles in malignant progression and treatment resistance. Cancer cells, often characterized by persistent high levels of reactive oxygen species (ROS) resulting from genetic, metabolic, and microenvironmental alterations, counterbalance this by enhancing their antioxidant capacity. Cysteine availability emerges as a critical factor in chemoresistance, shaping the survival dynamics of non-small cell lung cancer (NSCLC) cells. Selenium-chrysin (SeChry) was disclosed as a modulator of cysteine intracellular availability. This study comprehensively characterizes the metabolism of SeChry and investigates its cytotoxic effects in NSCLC. SeChry treatment induces notable metabolic shifts, particularly in selenocompound metabolism, impacting crucial pathways such as glycolysis, gluconeogenesis, the tricarboxylic acid (TCA) cycle, and amino acid metabolism. Additionally, SeChry affects the levels of key metabolites such as acetate, lactate, glucose, and amino acids, contributing to disruptions in redox homeostasis and cellular biosynthesis. The combination of SeChry with other treatments, such as glycolysis inhibition and chemotherapy, results in greater efficacy. Furthermore, by exploiting NSCLC's capacity to consume lactate, the use of lactic acid-conjugated dendrimer nanoparticles for SeChry delivery is investigated, showing specificity to cancer cells expressing monocarboxylate transporters.

Feedforward cysteine regulation maintains melanoma differentiation state and limits metastatic spread

The inherent ability of melanoma cells to alter the differentiation-associated transcriptional repertoire to evade treatment and facilitate metastatic spread is well accepted and has been termed phenotypic switching. However, how these facets of cellular behavior are controlled remains largely elusive. Here, we show that cysteine availability, whether from lysosomes (CTNS-dependent) or exogenously derived (SLC7A11-dependent or as N-acetylcysteine), controls melanoma differentiation-associated pathways by acting on the melanocyte master regulator MITF. Functional data indicate that low cysteine availability reduces MITF levels and impairs lysosome functions, which affects tumor ferroptosis sensitivity but improves metastatic spread in vivo. Mechanistically, cysteine-restrictive conditions reduce acetyl-CoA levels to decrease p300-mediated H3K27 acetylation at the melanocyte-restricted MITF promoter, thus forming a cysteine feedforward regulation that controls MITF levels and downstream lysosome functions. These findings collectively suggest that cysteine homeostasis governs melanoma differentiation by maintaining MITF levels and lysosome functions, which protect against ferroptosis and limit metastatic spread.

Comparative Analysis of Breast Cancer Metabolomes Highlights Fascin's Central Role in Regulating Key Pathways Related to Disease Progression

Omics technologies provide useful tools for the identification of novel biomarkers in many diseases, including breast cancer, which is the most diagnosed cancer in women worldwide. We and others have reported a central role for the actin-bundling protein (fascin) in regulating breast cancer disease progression at different levels. However, whether fascin expression promotes metabolic molecules that could predict disease progression has not been fully elucidated. Here, fascin expression was manipulated via knockdown (fascinKD+NORF) and rescue (fascinKD+FORF) in the naturally fascin-positive (fascinpos+NORF) MDA-MB-231 breast cancer cells. Whether fascin dysregulates metabolic profiles that are associated with disease progression was assessed using untargeted metabolomics analyses via liquid chromatography-mass spectrometry. Overall, 12,226 metabolic features were detected in the tested cell pellets. Fascinpos+NORF cell pellets showed 2510 and 3804 significantly dysregulated metabolites compared to their fascinKD+NORF counterparts. Fascin rescue (fascinKD+FORF) revealed 2710 significantly dysregulated cellular metabolites compared to fascinKD+NORF counterparts. A total of 101 overlapped cellular metabolites between fascinKD+FORF and fascinpos+NORF were significantly dysregulated in the fascinKD+NORF cells. Analysis of the significantly dysregulated metabolites by fascin expression revealed their involvement in the metabolism of sphingolipid, phenylalanine, tyrosine, and tryptophan biosynthesis, and pantothenate and CoA biosynthesis, which are critical pathways for breast cancer progression. Our findings of fascin-mediated alteration of metabolic pathways could be used as putative poor prognostic biomarkers and highlight other underlying mechanisms of fascin contribution to breast cancer progression.

Disulfidptosis: A Novel Prognostic Criterion and Potential Treatment Strategy for Diffuse Large B-Cell Lymphoma (DLBCL)

Diffuse Large B-cell Lymphoma (DLBCL), with its intrinsic genetic and epigenetic heterogeneity, exhibits significantly variable clinical outcomes among patients treated with the current standard regimen. Disulfidptosis, a novel form of regulatory cell death triggered by disulfide stress, is characterized by the collapse of cytoskeleton proteins and F-actin due to intracellular accumulation of disulfides. We investigated the expression variations of disulfidptosis-related genes (DRGs) in DLBCL using two publicly available gene expression datasets. The initial analysis of DRGs in DLBCL (GSE12453) revealed differences in gene expression patterns between various normal B cells and DLBCL. Subsequent analysis (GSE31312) identified DRGs strongly associated with prognostic outcomes, revealing eight characteristic DRGs (CAPZB, DSTN, GYS1, IQGAP1, MYH9, NDUFA11, NDUFS1, OXSM). Based on these DRGs, DLBCL patients were stratified into three groups, indicating that (1) DRGs can predict prognosis, and (2) DRGs can help identify novel therapeutic candidates. This study underscores the significant role of DRGs in various biological processes within DLBCL. Assessing the risk scores of individual DRGs allows for more precise stratification of prognosis and treatment strategies for DLBCL patients, thereby enhancing the effectiveness of clinical practice.

Bridging the Gap in Cancer Research: Sulfur Metabolism of Leukemic Cells with a Focus on L-Cysteine Metabolism and Hydrogen Sulfide-Producing Enzymes

Leukemias are cancers of the blood-forming system, representing a significant challenge in medical science. The development of leukemia cells involves substantial disturbances within the cellular machinery, offering hope in the search for effective selective treatments that could improve the 5-year survival rate. Consequently, the pathophysiological processes within leukemia cells are the focus of critical research. Enzymes such as cystathionine beta-synthase and sulfurtransferases like thiosulfate sulfurtransferase, 3-mercaptopyruvate sulfurtransferase, and cystathionine gamma-lyase play a vital role in cellular sulfur metabolism. These enzymes are essential to maintaining cellular homeostasis, providing robust antioxidant defenses, and supporting cell division. Numerous studies have demonstrated that cancerous processes can alter the expression and activity of these enzymes, uncovering potential vulnerabilities or molecular targets for cancer therapy. Recent laboratory research has indicated that certain leukemia cell lines may exhibit significant changes in the expression patterns of these enzymes. Analysis of the scientific literature and online datasets has confirmed variations in sulfur enzyme function in specific leukemic cell lines compared to normal leukocytes. This comprehensive review collects and analyzes available information on sulfur enzymes in normal and leukemic cell lines, providing valuable insights and identifying new research pathways in this field.

The emerging role and clinicopathological significance of MFSD12 in cancer and lysosomal storage diseases

MFSD12 protein has recently risen as a key factor in malignancy and plays a potential role in a variety of complex oncogenic signaling cascades. Current studies suggest that MFSD12 has a positive complex role in the growth and progression of tumors such as melanoma, breast cancer, and lung cancer. At the same time, as a transporter of cysteine, MFSD12 is also involved in the development of lysosomal storage diseases. Therefore, MFSD12 may be an effective target to inhibit tumor development, block metastasis, and expand the therapeutic effect. This article reviews the molecular mechanisms of MFSD12 in a variety of cancers and lysosomal storage diseases.

Transcriptional control of a metabolic switch regulating cellular methylation reactions is part of a common response to stress in divergent bee species

Recent global declines in bee health have elevated the need for a more complete understanding of the cellular stress mechanisms employed by diverse bee species. We recently uncovered the biomarker lethal (2) essential for life [l(2)efl] genes as part of a shared transcriptional program in response to a number of cell stressors in the western honey bee (Apis mellifera). Here, we describe another shared stress-responsive gene, glycine N-methyltransferase (Gnmt), which is known as a key metabolic switch controlling cellular methylation reactions. We observed Gnmt induction by both abiotic and biotic stressors. We also found increased levels of the GNMT reaction product sarcosine in the midgut after stress, linking metabolic changes with the observed changes in gene regulation. Prior to this study, Gnmt upregulation had not been associated with cellular stress responses in other organisms. To determine whether this novel stress-responsive gene would behave similarly in other bee species, we first characterized the cellular response to endoplasmic reticulum (ER) stress in lab-reared adults of the solitary alfalfa leafcutting bee (Megachile rotundata) and compared this with age-matched honey bees. The novel stress gene Gnmt was induced in addition to a number of canonical gene targets induced in both bee species upon unfolded protein response (UPR) activation, suggesting that stress-induced regulation of cellular methylation reactions is a common feature of bees. Therefore, this study suggests that the honey bee can serve as an important model for bee biology more broadly, although studies on diverse bee species will be required to fully understand global declines in bee populations.

Exploiting the metabolic vulnerability of circulating tumour cells

Metastasis has a major part in the severity of disease and lethality of cancer. Circulating tumour cells (CTCs) represent a reservoir of metastatic precursors in circulation, most of which cannot survive due to hostile conditions in the bloodstream. Surviving cells colonise a secondary site based on a combination of physical, metabolic, and oxidative stress protection states required for that environment. Recent advances in CTC isolation methods and high-resolution 'omics technologies are revealing specific metabolic pathways that support this selection of CTCs. In this review, we discuss recent advances in our understanding of CTC biology and discoveries of adaptations in metabolic pathways during their selection. Understanding these traits and delineating mechanisms by which they confer acquired resistance or vulnerability in CTCs is crucial for developing successful prognostic and therapeutic strategies in cancer.

Dissecting hair breakage in alopecia areata: the central role of dysregulated cysteine homeostasis

In the initial stages of Alopecia Areata (AA), the predominance of hair breakage or exclamation mark hairs serves as vital indicators of disease activity. These signs are non-invasive and are commonly employed in dermatoscopic examinations. Despite their clinical salience, the underlying etiology precipitating this hair breakage remains largely uncharted territory. Our exhaustive review of the existing literature points to a pivotal role for cysteine-a key amino acid central to hair growth-in these mechanisms. This review will probe and deliberate upon the implications of aberrant cysteine metabolism in the pathogenesis of AA. It will examine the potential intersections of cysteine metabolism with autophagy, ferroptosis, immunity, and psychiatric manifestations associated with AA. Such exploration could illuminate new facets of the disease's pathophysiology, potentially paving the way for innovative therapeutic strategies.

A novel disulfidptosis-related gene signature predicts overall survival of glioblastoma patients

Aim: The aim of this study was to investigate the prognostic relevance of disulfidptosis-related genes in glioblastoma using bioinformatic analysis in The Cancer Genome Atlas Program-Glioblastoma (TCGA-GBM) database and develop a gene signature model for predicting patient prognosis. Methods: We conducted a bioinformatic analysis using the TCGA-GBM database and employed weighted co-expression network analysis to identify disulfidptosis-related genes. Subsequently, we developed a predictive gene signature model based on these genes to stratify glioblastoma patients into high and low-risk groups. Results: Patients categorized into the high-risk group based on the disulfidptosis-related gene signature exhibited a significantly reduced survival rate in comparison to those in the low-risk group. Functional analysis also revealed notable differences in the immune status between the two risk groups. Conclusion: In conclusion, a new disulfidptosis-related gene signature can be utilised to predict prognosis in GBM.

Chiral Induction in 2D Borophene Nanoplatelets through Stereoselective Boron-Sulfur Conjugation

Chirality is a structural metric that connects biological and abiological forms of matter. Although much progress has been made in understanding the chemistry and physics of chiral inorganic nanoparticles over the past decade, almost nothing is known about chiral two-dimensional (2D) borophene nanoplatelets and their influence on complex biological networks. Borophene's polymorphic nature, derived from the bonding configurations among boron atoms, distinguishes it from other 2D materials and allows for further customization of its material properties. In this study, we describe a synthetic methodology for producing chiral 2D borophene nanoplatelets applicable to a variety of structural polymorphs. Using this methodology, we demonstrate feasibility of top-down synthesis of chiral χ3 and β12 phases of borophene nanoplatelets via interaction with chiral amino acids. The chiral nanoplatelets were physicochemically characterized extensively by various techniques. Results indicated that the thiol presenting amino acids, i.e., cysteine, coordinates with borophene in a site-selective manner, depending on its handedness through boron-sulfur conjugation. The observation has been validated by circular dichroism, X-ray photoelectron spectroscopy, and 11B NMR studies. To understand how chiral nanoplatelets interact with biological systems, mammalian cell lines were exposed to them. Results showed that the achiral as well as the left- and right-handed biomimetic χ3 and β12 borophene nanoplatelets have distinct interaction with the cellular membrane, and their internalization pathway differs with their chirality. By engineering optical, physical, and chemical properties, these chiral 2D nanomaterials could be applied successfully to tuning complex biological events and find applications in photonics, sensing, catalysis, and biomedicine.

Unresolved questions regarding cellular cysteine sources and their possible relationships to ferroptosis

Cysteine is required for synthesis of glutathione (GSH), coenzyme A, other sulfur-containing metabolites, and most proteins. In most cells, cysteine comes from extracellular disulfide sources including cystine, glutathione-disulfide, and peptides. The thioredoxin reductase-1 (TrxR1)- or glutathione-disulfide reductase (GSR)-driven enzymatic systems can fuel cystine reduction via thioredoxins, glutaredoxins, or other thioredoxin-fold proteins. Free cystine enters cells thorough the cystine-glutamate antiporter, xCT, but systemically, plasma glutathione-disulfide might predominate as a cystine source. Erastin, inhibiting both xCT and voltage-dependent anion channels, induces ferroptotic cell death, so named because this type of cell death is antagonized by iron-chelators. Many cancer cells seem to be predisposed to ferroptosis, which has been proposed as a targetable cancer liability. Ferroptosis is associated with lipid peroxidation and loss of either glutathione peroxidase-4 (GPX4) or ferroptosis suppressor protein-1 (FSP1), which each prevent accumulation of lipid peroxides. It has been suggested that an xCT inhibition-induced cellular cysteine-deficiency lowers GSH levels, starving GPX4 for reducing power and allowing membrane lipid peroxides to accumulate, thereby causing ferroptosis. Aspects of ferroptosis are however not fully understood and need to be further scrutinized, for example that neither disruption of GSH synthesis, loss of GSH, nor disruption of glutathione disulfide reductase (GSR), triggers ferroptosis in animal models. Here we reevaluate the relationships between Erastin, xCT, GPX4, cellular cysteine and GSH, RSL3 or ML162, and ferroptosis. We conclude that, whereas both Cys and ferroptosis are potential liabilities in cancer, their relationship to each other remains insufficiently understood.

Ferroptosis and its role in gastric and colorectal cancers

Ferroptosis is a novel mechanism of programmed cell death, characterized by intracellular iron overload, intensified lipid peroxidation, and abnormal accumulation of reactive oxygen species, which ultimately resulting in cell membrane impairment and demise. Research has revealed that cancer cells exhibit a greater demand for iron compared to normal cells, indicating a potential susceptibility of cancer cells to ferroptosis. Stomach and colorectal cancers are common gastrointestinal malignancies, and their elevated occurrence and mortality rates render them a global health concern. Despite significant advancements in medical treatments, certain unfavorable consequences and drug resistance persist. Consequently, directing attention towards the phenomenon of ferroptosis in gastric and colorectal cancers holds promise for enhancing therapeutic efficacy. This review aims to elucidate the intricate cellular metabolism associated with ferroptosis, encompassing lipid and amino acid metabolism, as well as iron metabolic processes. Furthermore, the significance of ferroptosis in the context of gastric and colorectal cancer is thoroughly examined and discussed.

ATF3-CBS signaling axis coordinates ferroptosis and tumorigenesis in colorectal cancer

The induction of ferroptosis is promising for cancer therapy. However, the mechanisms enabling cancer cells to evade ferroptosis, particularly in low-cystine environments, remain elusive. Our study delves into the intricate regulatory mechanisms of Activating transcription factor 3 (ATF3) on Cystathionine β-synthase (CBS) under cystine deprivation stress, conferring resistance to ferroptosis in colorectal cancer (CRC) cells. Additionally, our findings establish a positively correlation between this signaling axis and CRC progression, suggesting its potential as a therapeutic target. Mechanistically, ATF3 positively regulates CBS to resist ferroptosis under cystine deprivation stress. In contrast, the suppression of CBS sensitizes CRC cells to ferroptosis through targeting the mitochondrial tricarboxylic acid (TCA) cycle. Notably, our study highlights that the ATF3-CBS signaling axis enhances ferroptosis-based CRC cancer therapy. Collectively, the findings reveal that the ATF3-CBS signaling axis is the primary feedback pathway in ferroptosis, and blocking this axis could be a potential therapeutic approach for colorectal cancer.

Programming a Ferroptosis-to-Apoptosis Transition Landscape Revealed Ferroptosis Biomarkers and Repressors for Cancer Therapy

Ferroptosis and apoptosis are key cell-death pathways implicated in several human diseases including cancer. Ferroptosis is driven by iron-dependent lipid peroxidation and currently has no characteristic biomarkers or gene signatures. Here a continuous phenotypic gradient between ferroptosis and apoptosis coupled to transcriptomic and metabolomic landscapes is established. The gradual ferroptosis-to-apoptosis transcriptomic landscape is used to generate a unique, unbiased transcriptomic predictor, the Gradient Gene Set (GGS), which classified ferroptosis and apoptosis with high accuracy. Further GGS optimization using multiple ferroptotic and apoptotic datasets revealed highly specific ferroptosis biomarkers, which are robustly validated in vitro and in vivo. A subset of the GGS is associated with poor prognosis in breast cancer patients and PDXs and contains different ferroptosis repressors. Depletion of one representative, PDGFA-assaociated protein 1(PDAP1), is found to suppress basal-like breast tumor growth in a mouse model. Omics and mechanistic studies revealed that ferroptosis is associated with enhanced lysosomal function, glutaminolysis, and the tricarboxylic acid (TCA) cycle, while its transition into apoptosis is attributed to enhanced endoplasmic reticulum(ER)-stress and phosphatidylethanolamine (PE)-to-phosphatidylcholine (PC) metabolic shift. Collectively, this study highlights molecular mechanisms underlying ferroptosis execution, identified a highly predictive ferroptosis gene signature with prognostic value, ferroptosis versus apoptosis biomarkers, and ferroptosis repressors for breast cancer therapy.

Formyl-Peptide Receptor 2 Signaling Modulates SLC7A11/xCT Expression and Activity in Tumor Cells

Cancer cells exhibit high levels of oxidative stress and consequently require a high amount of cysteine for glutathione synthesis. Solute Carrier Family 7 Member 11 (SLC7A11), or xCT, mediates the cellular uptake of cystine in exchange for intracellular glutamate; imported extracellular cystine is reduced to cysteine in the cytosol through a NADPH-consuming reduction reaction. SLC7A11/xCT expression is under the control of stress-inducing conditions and of several transcription factors, such as NRF2 and ATF4. Formyl-peptide receptor 2 (FPR2) belongs to the FPR family, which transduces chemotactic signals mediating either inflammatory or anti-inflammatory responses according to the nature of its ligands and/or FPR2 binding with other FPR isoforms. The repertoire of FPR2 agonists with anti-inflammatory activities comprises WKYMVm peptide and Annexin A1 (ANXA1), and the downstream effects of the intracellular signaling cascades triggered by FPR2 include NADPH oxidase (NOX)-dependent generation of reactive oxygen species. Herein, we demonstrate that stimulation of CaLu-6 cells with either WKYMVm or ANXA1: (i) induces the redox-regulated activation of SLC7A11/xCT; (ii) promotes the synthesis of glutathione; (iii) prevents lipid peroxidation; and (iv) favors NRF2 nuclear translocation and activation. In conclusion, our overall results demonstrate that FPR2 agonists and NOX modulate SLC7A11/xCT expression and activity, thereby identifying a novel regulative pathway of the cystine/glutamate antiport that represents a new potential therapeutical target for the treatment of human cancers.

Disulfidptosis decoded: a journey through cell death mysteries, regulatory networks, disease paradigms and future directions

Cell death is an important part of the life cycle, serving as a foundation for both the orderly development and the maintenance of physiological equilibrium within organisms. This process is fundamental, as it eliminates senescent, impaired, or aberrant cells while also promoting tissue regeneration and immunological responses. A novel paradigm of programmed cell death, known as disulfidptosis, has recently emerged in the scientific circle. Disulfidptosis is defined as the accumulation of cystine by cancer cells with high expression of the solute carrier family 7 member 11 (SLC7A11) during glucose starvation. This accumulation causes extensive disulfide linkages between F-actins, resulting in their contraction and subsequent detachment from the cellular membrane, triggering cellular death. The RAC1-WRC axis is involved in this phenomenon. Disulfidptosis sparked growing interest due to its potential applications in a variety of pathologies, particularly oncology, neurodegenerative disorders, and metabolic anomalies. Nonetheless, the complexities of its regulatory pathways remain elusive, and its precise molecular targets have yet to be definitively identified. This manuscript aims to meticulously dissect the historical evolution, molecular underpinnings, regulatory frameworks, and potential implications of disulfidptosis in various disease contexts, illuminating its promise as a groundbreaking therapeutic pathway and target.

Plasma Metabolite Profiling in the Search for Early-Stage Biomarkers for Lung Cancer: Some Important Breakthroughs

Lung cancer is the leading cause of cancer-related mortality worldwide. In order to improve its overall survival, early diagnosis is required. Since current screening methods still face some pitfalls, such as high false positive rates for low-dose computed tomography, researchers are still looking for early biomarkers to complement existing screening techniques in order to provide a safe, faster, and more accurate diagnosis. Biomarkers are biological molecules found in body fluids, such as plasma, that can be used to diagnose a condition or disease. Metabolomics has already been shown to be a powerful tool in the search for cancer biomarkers since cancer cells are characterized by impaired metabolism, resulting in an adapted plasma metabolite profile. The metabolite profile can be determined using nuclear magnetic resonance, or NMR. Although metabolomics and NMR metabolite profiling of blood plasma are still under investigation, there is already evidence for its potential for early-stage lung cancer diagnosis, therapy response, and follow-up monitoring. This review highlights some key breakthroughs in this research field, where the most significant biomarkers will be discussed in relation to their metabolic pathways and in light of the altered cancer metabolism.