Amino Acid Depletion Therapies: Starving Cancer Cells to Death

Metabolic reprogramming of tumor microenviroment by engineered bacteria

The tumor microenvironment (TME) is a complex ecosystem that plays a crucial role in tumor progression and response to therapy. The metabolic characteristics of the TME are fundamental to its function, influencing not only cancer cell proliferation and survival but also the behavior of immune cells within the tumor. Metabolic reprogramming-where cancer cells adapt their metabolic pathways to support rapid growth and immune evasion-has emerged as a key factor in cancer immunotherapy. Recently, the potential of engineered bacteria in cancer immunotherapy has gained increasing recognition, offering a novel strategy to modulate TME metabolism and enhance antitumor immunity. This review summarizes the metabolic properties and adaptations of tumor and immune cells within the TME and summarizes the strategies by which engineered bacteria regulate tumor metabolism. We discuss how engineered bacteria can overcome the immunosuppressive TME by reprogramming its metabolism to improve antitumor therapy. Furthermore, we examine the advantages, potential challenges, and future clinical translation of engineered bacteria in reshaping TME metabolism.

Metabolic reprogramming of drug resistance in pancreatic cancer: mechanisms and effects

Pancreatic cancer is a highly aggressive gastrointestinal malignancy, often termed the "king of cancers" due to its notoriously high mortality rate. Its clinical characteristics, including late diagnosis, low surgical resectability, high recurrence rates, significant chemoresistance, and poor prognosis have collectively driven the persistent rise in incidence and mortality. Despite ongoing advancements in therapeutic strategies, the management of pancreatic cancer, particularly at advanced stages, remains challenging. Chemotherapy remains the mainstay of current treatment. However, the prevalent problem of chemotherapy resistance poses a significant obstacle to effective treatment. Metabolic reprogramming, characterized by alterations in glucose metabolism, lipid biosynthesis, and amino acid utilization, supports the high energy demands and rapid proliferation of cancer cells. Emerging evidence suggests that these metabolic changes, possibly mediated by epigenetic mechanisms, also contribute to tumorigenesis and metastasis. These findings highlight the critical role of metabolic alterations in pancreatic cancer pathogenesis. This review explores the relationship between metabolic reprogramming and chemotherapy resistance, discussing underlying mechanisms and summarizing preclinical studies and drug development targeting metabolism. The aim is to provide a comprehensive perspective on potential therapeutic strategies for pancreatic cancer.

Nanomaterials in cancer starvation therapy: pioneering advances, therapeutic potential, and clinical challenges

Gaining significant attention in recent years, starvation therapy based on the blocking nutrients supply to cancer cells via blood occlusion and metabolic interventions is a promisingly novel approach in cancer treatment. However, there are many crucial obstacles to overcome to achieve effective treatment, for example, poor-targeting delivery, cellular hypoxia, adverse effects, and ineffective monotherapy. The starvation-based multitherapy based on multifunctional nanomaterials can narrow these gaps and pave a promising way for future clinical translation. This review focuses on the progression in nanomaterials-mediated muti-therapeutic modalities based on starvation therapy in recent years and therapeutic limitations that prevent their clinical applications. Moreover, unlike previous reviews that focused on a single aspect of the field, this comprehensive review presents a broader perspective on starvation therapy by summarising advancements across its various therapeutic strategies.

Methionine Metabolism Dictates PCSK9 Expression and Antitumor Potency of PD-1 Blockade in MSS Colorectal Cancer

Nutrient metabolisms are vitally interrelated to cancer progression and immunotherapy. However, the mechanisms by which nutrient metabolisms interact to remodel immune surveillance within the tumor microenvironment remain largely unexplored. Here it is demonstrated that methionine restriction inhibits the expression of proprotein convertase subtilisin/kexin type 9 (PCSK9), a key regulator of cholesterol homeostasis and a potential target for cancer immunotherapy, in colorectal cancer (CRC) but not in the liver. Mechanistically, methionine is catabolized to S-adenosylmethionine (SAM), promoting mRNA transcription of PCSK9 through increased DNA methyltransferase 1 (DNMT1)-mediated DNA methylation and suppression of sirtuin 6 (SIRT6) expression. Furthermore, both PCSK9 inhibition and dietary methionine restriction (DMR) potentiate PD-1 blockade therapy and foster the infiltration of CD8+ T cells in Colon 26 tumor-bearing mice-a proficient mismatch repair (pMMR)/microsatellite stable (MSS) CRC model that exhibits limited response to anti-PD-1 therapy. Moreover, combining 5-fluorouracil (5-FU) chemotherapy with PCSK9 inhibition and PD-1 blockade further augments therapeutic efficacy for MSS CRC. The findings establish a mechanistic link between amino acid metabolism and cholesterol metabolism within the tumor microenvironment where tumor cells sense methionine to regulate PCSK9 expression, highlighting promising combination therapeutic strategies that may greatly benefit MSS CRC patients.

Methionine Dependency and Restriction in Cancer: Exploring the Pathogenic Function and Therapeutic Potential

Methionine, an essential amino acid, is obtained by dietary intake to fulfill the requirements of our bodies. Accumulating evidence indicates that methionine plays a pivotal role in various biological processes, including protein synthesis, energy metabolism, redox balance maintenance, and methylation modifications. Numerous advances underscore the heightened dependence of cancer cells on methionine, which is a significant factor in cancer pathogenesis and development. A profound comprehension of the intricate relationship between methionine metabolism and tumorigenesis is imperative for advancing the field of cancer therapeutics. Herein, we delve into the role of methionine in supporting cancer growth, the impact on epigenetic modifications, and the interaction between methionine and the tumor microenvironment. Additionally, we provide insights into the development of various methionine-targeted therapy strategies. This paper summarizes the current state of research and its translational potential, emphasizing the challenges and opportunities associated with harnessing methionine dependence as a target for innovative cancer treatments.

SOD2 is a regulator of proteasomal degradation promoting an adaptive cellular starvation response

Adaptation to changes in amino acid availability is crucial for cellular homeostasis, which requires an intricate orchestration of involved pathways. Some cancer cells can maintain cellular fitness upon amino acid shortage, which has a poorly understood mechanistic basis. Leveraging a genome-wide CRISPR-Cas9 screen, we find that superoxide dismutase 2 (SOD2) has a previously unrecognized dismutase-independent function. We demonstrate that SOD2 regulates global proteasomal protein degradation and promotes cell survival under conditions of metabolic stress in malignant cells through the E3 ubiquitin ligases UBR1 and UBR2. Consequently, inhibition of SOD2-mediated protein degradation highly sensitizes different cancer entities, including patient-derived xenografts, to amino acid depletion, highlighting the pathophysiological relevance of our findings. Our study reveals that SOD2 is a regulator of proteasomal protein breakdown upon starvation, which serves as an independent catabolic source of amino acids, a mechanism co-opted by cancer cells to maintain cellular fitness.

Extracellular Vesicle-Packaged Linc-ZNF25-1 from Pancreatic Cancer Cell Promotes Pancreatic Stellate Cell Uptake of Asparagine to Advance Chemoresistance

Extensive fibrous stroma plays an important role in gemcitabine (GEM) resistance. However, the mechanism by which pancreatic cancer cells interact with pancreatic stellate cells (PSCs) to promote GEM resistance remains unclear. This study investigates the role of metabolic crosstalk between these two cells in inducing GEM resistance. Extracellular vesicles (EVs) of parental and GEM-resistant pancreatic cancer cells are extracted and performed metabolic assays and long noncoding RNA (lncRNA) sequencing. Pancreatic cancer cell-derived EVs promote PSCs activation and extracellular matrix formation, and GEM-resistant pancreatic cancer cells produce more asparagine (Asn), favoring PSCs activation. Mechanistically, pancreatic cancer cell-derived EVs mediate linc-ZNF25-1 to promote Asn uptake via the IGF2BP3/c-Myc/SLC1A5 pathway in PSCs. In addition, mouse models elucidate the oncogenic function of linc-ZNF25-1 and the enhanced therapeutic effect of asparaginase (L-ASNase) in combination with GEM in pancreatic cancer. This study demonstrates that pancreatic cancer cell-derived EVs promote the uptake of Asn released from pancreatic cancer cells through the upregulation of SLC1A5 in PSCs, facilitating PSCs activation and pancreatic cancer resistance to GEM. L-ASNase in combination with GEM is a potential therapeutic strategy for targeting stromal cells to enhance the efficacy of chemotherapeutic agents against pancreatic cancer.

Cell-type dependent effect of 3D collagen matrix on cancer cell resistance to suboptimal conditions: the case of serum deprivation, glucose starvation, and hypoxia

The extracellular matrix (ECM) and its primary chemical components, including collagen, play a pivotal role in carcinogenesis and tumor progression. The ECM actively regulates cell proliferation, migration, and, importantly, resistance to various adverse factors. It is widely recognized as a key factor in modifying the resistance of tumor cells to various treatment modalities and cytotoxic compounds. However, the role of the ECM in tumor cell adaptation to nutritional deficiencies and hypoxic conditions remains significantly less studied. Since it is generally accepted that tumor cells resistance increases when cultured in a three-dimensional matrix, we sought to experimentally test the universality of this statement. In this work, we analyzed the responses of tumor cells with varying origins and proliferative activities, including human bladder carcinoma, epidermoid carcinoma, and ovarian carcinoma, to deprivation of serum, glucose and oxygen. We compared cell resistance to suboptimal conditions when cultured in a monolayer on tissue culture (TC)-treated polystyrene, on collagen-coated surfaces, or within a three-dimensional hydrogel composed of collagen type I. All three cell lines were stably transfected with fluorescent protein genes. To register the cell growth dynamics, we used a fluorescence-based technique that allows long-term quantitative observations without disrupting the hydrogel. The analyzed cell lines demonstrated different patterns of relative sensitivity to suboptimal conditions. We revealed that the direction and intensity of the collagen matrix effect depend on the cell type. Slowly proliferating ovarian carcinoma cells showed no noticeable changes in their behavior when cultured in a gel compared to a monolayer. In the case of bladder carcinoma, we registered predominantly resistance-stimulating effect of the collagen matrix, but it was significant only under serum deprivation. The most pronounced effect of collagen was registered for epidermoid carcinoma. Importantly, this effect was ambivalent: gel-embedded cells demonstrated significantly enhanced resistance to serum deprivation, but, at the same time, they were more responsive to glucose starvation and hypoxic conditions. We attribute the registered phenomenon to the individual characteristics of tumor cells with different origins and metabolic activities.

Exploring the complex relationship between metabolomics and breast cancer early detection (Review)

An overview of metabolomics in cancer research, focusing on the identification of biomarkers, pharmacological targets and therapeutic agents, is provided in the present review. The fundamentals of metabolomics, the role of metabolites in cancer emergence and the methods used in metabolomic analysis, are reviewed. The applications of metabolomics in cancer therapy and diagnostics, as well as the challenges encountered in metabolomic research, are discussed. Finally, the potential clinical uses of metabolomics in cancer research and its future possibilities are explored, emphasising the importance of non-invasive diagnostic and monitoring techniques. The present review highlights the significance of metabolite-based metabolomics as a specialised tool for illuminating disease processes and identifying treatment potentials. The malfunctioning of metabolomic pathways and metabolite accumulation or depletion is caused by metabolomics abnormalities. Metabolite signatures close to a subject's phenotypic informative dimension can be used to monitor therapies and disease prediction diagnosis and prognosis. Non-invasive diagnostic and monitoring techniques with high specificity and selectivity are urgently needed. Metabolite-based metabolomics is a specialised metabolic biomarker and pathway-analysis technique, illuminating the putative processes of numerous human illnesses and determining treatment potentials. Locating biochemical pathway modifications that are early warning signs of pathological malfunction and illness is possible by identifying functional biomarkers linked to phenotypic variance. Scientists generated numerous metabolomics profiles to disclose the underlying processes and metabolomics networks for therapeutic target research in biomedicine. The metabolomic analysis of the potential utility of metabolites as biomarkers for clinical events is summarised in the present review. The significance of metabolite-based metabolomics as a specialised tool for illuminating disease processes and identifying treatment potentials is highlighted.

Ultrasensitive Determination of Amino Acids in Single Cells by Chemical Isotope Labeling with Liquid Chromatography Mass Spectrometry Analysis

Amino acids play multiple critical roles in the regulation of various metabolic pathways and physiological processes in living organisms. Mass spectrometry (MS) has become the most pioneering platform for amino acid analysis. However, the simultaneous and sensitive determination of amino acids is still challenging because of their structural similarity and broad ranges of concentrations. To this end, a pair of isotope labeling reagents, d0/d3-2-((diazomethyl)phenyl)(9-methyl-1,3,4,9-tetrahydro-2H-pyrido[3,4-b]indol-2-yl) methanone (DMPI/d3-DMPI), were applied to label amino acid metabolites. The diazo groups on the pair of isotopomers (DMPI/d3-DMPI) can specifically react with the carboxyl groups on the amino acids. The results showed that the retention on reversed-phase column were enhanced and the detection sensitivities of 19 amino acids were increased benefiting from DMPI labeling strategy that transfers the hydrophobic indole heterocycle group of DMPI to the hydrophilic compounds of amino acids. The obtained limits of detection (LODs) of amino acids were in the range of 0.002-0.082 fmol. With this established method, we achieved the sensitive detection of amino acids in a single HUVE cell. Meanwhile, we found that the contents of amino acids in the serum of premature neonates were higher compared to normal neonates. Overall, this developed method provides great support of detection tool for the clinical metabolomic study of amino acids and the investigation of dynamic changes of amino acid metabolism in single cells.

Methionine metabolite spermidine inhibits tumor pyroptosis by enhancing MYO6-mediated endocytosis

The connection between amino acid metabolism and pyroptosis remains elusive. Herein, we screen the effect of individual amino acid on pyroptosis and identify that methionine inhibits GSDME-mediated pyroptosis. Mechanistic analyses unveil that MYO6, a unique actin-based motor protein, bridges the GSDME N-terminus (GSDME-NT) and the endocytic adaptor AP2, mediating endolysosomal degradation of GSDME-NT. This degradation is increased by the methionine-derived metabolite spermidine noncanonically by direct binding to MYO6, which enhances MYO6 selectivity for GSDME-NT. Moreover, combination targeted therapies using dietary or pharmacological inhibition in methionine-to-spermidine metabolism in the tumor promotes pyroptosis and anti-tumor immunity, leading to a stronger tumor-suppressive effect in in vivo models. Clinically, higher levels of tumor spermidine and expression of methionine-to-spermidine metabolism-related gene signature predict poorer survival. Conclusively, our research identifies an unrecognized mechanism of pyroptotic resistance mediated by methionine-spermidine metabolic axis, providing a fresh angle for cancer treatment.

Mass spectrometry-based analysis of eccrine sweat supports predictive, preventive and personalised medicine in a cohort of breast cancer patients in Austria

Objective

Metabolomics measurements of eccrine sweat may provide novel and relevant biomedical information to support predictive, preventive and personalised medicine (3PM). However, only limited data is available regarding metabolic alterations accompanying chemotherapy of breast cancer patients related to residual cancer burden (RCB) or therapy response. Here, we have applied Metabo-Tip, a non-invasive metabolomics assay based on the analysis of eccrine sweat from the fingertips, to investigate the feasibility of such an approach, especially with respect to drug monitoring, assessing lifestyle parameters and stratification of breast cancer patients.

Methods

Eccrine sweat samples were collected from breast cancer patients (n = 9) during the first cycle of neoadjuvant chemotherapy at four time points in this proof-of-concept study at a Tertiary University Hospital. Metabolites in eccrine sweat were analysed using mass spectrometry. Blood plasma samples from the same timepoints were also collected and analysed using a validated targeted metabolomics kit, in addition to proteomics and fatty acids/oxylipin analysis.

Results

A total of 247 exogenous small molecules and endogenous metabolites were identified in eccrine sweat of the breast cancer patients. Cyclophosphamide and ondansetron were successfully detected and monitored in eccrine sweat of individual patients and accurately reflected the administration schedule. The non-essential amino acids asparagine, serine and proline, as well as ornithine were significantly regulated in eccrine sweat and blood plasma over the therapy cycle. However, their distinct time-dependent profiles indicated compartment-specific distributions. Indeed, the metabolite composition of eccrine sweat seems to largely resemble the composition of the interstitial fluid. Plasma proteins and fatty acids/oxylipins were not affected by the first treatment cycle. Individual smoking habit was revealed by the simultaneous detection of nicotine and its primary metabolite cotinine in eccrine sweat. Stratification according to RCB revealed pronounced differences in the metabolic composition of eccrine sweat in these patients at baseline, e.g., essential amino acids, possibly due to the systemic contribution of breast cancer and its impact on metabolic turnover.

Conclusion

Mass spectrometry-based analysis of metabolites from eccrine sweat of breast cancer patients successfully qualified lifestyle parameters for risk assessment and allowed us to monitor drug treatment and systemic response to therapy. Moreover, eccrine sweat revealed a potentially predictive metabolic pattern stratifying patients by the extent of the metabolic activity of breast cancer tissue at baseline. Eccrine sweat is derived from the otherwise hardly accessible interstitial fluid and, thus, opens up a new dimension for biomonitoring of breast cancer in secondary and tertiary care. The simple sample collection without the need for trained personnel could also enable decentralised long-term biomonitoring to assess stable disease or disease progression. Eccrine sweat analysis may indeed significantly advance 3PM for the benefit of breast cancer patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-025-00396-6.

Muscle loss in cancer cachexia: what is the basis for nutritional support?

Cancer cachexia (CC) is characterized by significant skeletal muscle wasting, and contributes to diminished quality of life, while being associated with poorer response to treatment and with reduced survival. Chronic inflammation plays a central role in driving CC progression, within a complex interplay favoring catabolism. Although cachexia cannot be fully reversed by conventional nutritional support, nutritional intervention shows promise for the prevention and treatment of the syndrome. Of special interest are nutrients with antioxidant and anti-inflammatory potential and those that activate pathways involved in muscle mass synthesis and/or in the inhibition of muscle wasting. Extensive research has been carried out on novel nutritional supplements' power to mitigate CC impact, while the mechanisms through which some nutrients or bioactive compounds exert beneficial effects on muscle mass are still not totally clear. Here, we discuss the most studied supplements and nutritional strategies for dealing with muscle loss in CC.

Disrupted methionine cycle triggers muscle atrophy in cancer cachexia through epigenetic regulation of REDD1

The essential amino acid methionine plays a pivotal role in one-carbon metabolism, facilitating the production of S-adenosylmethionine (SAM), a critical supplier for DNA methylation and thereby a modulator of gene expression. Here, we report that the methionine cycle is disrupted in skeletal muscle during cancer cachexia, leading to endoplasmic reticulum stress and DNA hypomethylation-induced expression of the DNA damage inducible transcript 4 (Ddit4) gene, encoding the regulated in development and DNA damage response 1 (REDD1) protein. Targeting DNA methylation by depletion or pharmacological inhibition of DNA methyltransferase 3A (DNMT3A) exacerbates cachexia, while restoring DNMT3A expression or REDD1 knockout alleviates cancer cachexia-induced skeletal muscle atrophy in mice. Methionine supplementation restores DNA methylation of the Ddit4 promoter in a DNMT3A-dependent manner, thereby inhibiting activating transcription factor 4 (ATF4)-mediated Ddit4 transcription. Thus, with the identification of the methionine/SAM-DNMT3A/DNA hypomethylation-Ddit4/REDD1 axis, our study provides molecular insights into an epigenetic mechanism underlying cancer cachexia, and it suggests nutrient supplementation as a promising therapeutic strategy to prevent or reverse cachectic muscle atrophy.

Global metabolomic profiling of tumor tissue and paired serum samples to identify biomarkers for response to neoadjuvant FOLFIRINOX treatment of human pancreatic cancer

Neoadjuvant chemotherapy (NAT) is increasingly used for the treatment of non-metastatic pancreatic ductal adenocarcinoma (PDAC) and is established as a standard of care for borderline resectable and locally advanced PDAC. However, full exploitation of its clinical benefits is limited by the lack of biomarkers that assess treatment response. To address this unmet need, global metabolomic profiling was performed on tumor tissue and paired serum samples from patients with treatment-naïve (TN; n = 18) and neoadjuvant leucovorin calcium (folinic acid), fluorouracil, irinotecan hydrochloride and oxaliplatin (FOLFIRINOX)-treated (NAT; n = 17) PDAC using liquid chromatography mass spectrometry. Differentially abundant metabolites (DAMs) in TN versus NAT groups were identified and their correlation with various clinical parameters was assessed. Metabolomics profiling identified 40 tissue and five serum DAMs in TN versus NAT PDAC. In general, DAMs associated with amino acid and nucleotide metabolism were lower in NAT compared to TN. Four DAMs-3-hydroxybutyric acid (BHB), 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), glycochenodeoxycholate and citrulline-were common to both tissue and serum and showed a similar pattern of differential abundance in both groups. A strong positive correlation was observed between serum carbohydrate 19-9 antigen (CA 19-9) and tissue carnitines (C12, C18, C18:2) and N8-acetylspermidine. The reduction in CA 19-9 following NAT correlated negatively with serum deoxycholate levels, and the latter correlated positively with survival. This study revealed neoadjuvant-chemotherapy-induced changes in metabolic pathways in PDAC, mainly amino acid and nucleotide metabolism, and these correlated with reduced CA 19-9 following neoadjuvant FOLFIRINOX treatment.

Identification of an Amino Acid Metabolism Reprogramming Signature for Predicting Prognosis, Immunotherapy Efficacy, and Drug Candidates in Colon Cancer

Colon cancer ranked third among the most frequently diagnosed cancers worldwide. Amino acid metabolic reprogramming was related to the occurrence and development of colon cancer. We looked for the amino acid metabolism genes (AMGs) associated with amino acid metabolism from molecular signatures database as prognostic markers and constructed amino acid metabolism scoring model (AMS). According to AMS, the patients were divided into high AMS and low AMS groups, and the prognostic characteristics, molecular phenotypes, somatic cell mutation characteristics, immune cell infiltration characteristics, and immunotherapy effect of the two groups were systematically analyzed. Finally, the compounds targeting AMGs were also screened. We screen out 6 prognostic AMGs (P < 0.05) and construct an AMS model based on them. K-M curve indicated that OS in low AMS group was significantly higher than that in high group (P < 0.05), which were validated in multiple datasets. And different AMS groups had different molecular phenotypes, somatic cell mutation characteristics and immune cell infiltration characteristics. Low AMS group had a better effect for immunotherapy. In addition, we predicted potential therapeutic compounds that could bind to AMGs target proteins. AMS model can be used as a hierarchical tool to evaluate the prognosis, immune infiltration characteristics and immunotherapy response ability of colon cancer. And the compounds screened based on AMGs may become new anti-tumor drugs.

Nanomaterial-enabled metabolic reprogramming strategies for boosting antitumor immunity

Immunotherapy has become a crucial strategy in cancer treatment, but its effectiveness is often constrained. Most cancer immunotherapies focus on stimulating T-cell-mediated immunity by driving the cancer-immunity cycle, which includes tumor antigen release, antigen presentation, T cell activation, infiltration, and tumor cell killing. However, metabolism reprogramming in the tumor microenvironment (TME) supports the viability of cancer cells and inhibits the function of immune cells within this cycle, presenting clinical challenges. The distinct metabolic needs of tumor cells and immune cells require precise and selective metabolic interventions to maximize therapeutic outcomes while minimizing adverse effects. Recent advances in nanotherapeutics offer a promising approach to target tumor metabolism reprogramming and enhance the cancer-immunity cycle through tailored metabolic modulation. In this review, we explore cutting-edge nanomaterial strategies for modulating tumor metabolism to improve therapeutic outcomes. We review the design principles of nanoplatforms for immunometabolic modulation, key metabolic pathways and their regulation, recent advances in targeting these pathways for the cancer-immunity cycle enhancement, and future prospects for next-generation metabolic nanomodulators in cancer immunotherapy. We expect that emerging immunometabolic modulatory nanotechnology will establish a new frontier in cancer immunotherapy in the near future.

Cellular Signaling of Amino Acid Metabolism in Prostate Cancer

Prostate cancer is one of the most common malignancies affecting men worldwide and a leading cause of cancer-related mortality, necessitating a deeper understanding of its underlying biochemical pathways. Similar to other cancer types, prostate cancer is also characterised by aberrantly activated metabolic pathways that support tumour development, such as amino acid metabolism, which is involved in modulating key physiological and pathological cellular processes during the progression of this disease. The metabolism of several amino acids, such as glutamine and methionine, crucial for tumorigenesis, is dysregulated and commonly discussed in prostate cancer. And the roles of some less studied amino acids, such as histidine and glycine, have also been covered in prostate cancer studies. Aberrant regulation of two major signalling pathways, mechanistic target of rapamycin (mTOR) and general amino acid control non-depressible 2 (GCN2), is a key driver of reshaping the amino acid metabolism landscape in prostate cancer. By summarising our current understanding of how amino acid metabolism is modulated in prostate cancer, here, we provide further insights into certain potential therapeutic targets for managing prostate cancer through metabolic interventions.

The roles of KRAS in cancer metabolism, tumor microenvironment and clinical therapy

KRAS is one of the most mutated genes, driving alternations in metabolic pathways that include enhanced nutrient uptaking, increased glycolysis, elevated glutaminolysis, and heightened synthesis of fatty acids and nucleotides. However, the beyond mechanisms of KRAS-modulated cancer metabolisms remain incompletely understood. In this review, we aim to summarize current knowledge on KRAS-related metabolic alterations in cancer cells and explore the prevalence and significance of KRAS mutation in shaping the tumor microenvironment and influencing epigenetic modification via various molecular activities. Given that cancer cells rely on these metabolic changes to sustain cell growth and survival, targeting these processes may represent a promising therapeutic strategy for KRAS-driven cancers.

Hydration behavior of asparagine: an approach using time domain reflectometry at low temperatures

The dielectric behavior of Asparagine (C4H8N2O3) in water over the frequency range of 10 MHz to 30 GHz in the temperature region of 278.15-303.15 K in a step of 5 K has been carried out using time domain reflectometry (TDR) at various concentrations of asparagine. The obtained dielectric spectra reveal two relaxation peaks. The low frequency relaxation is attributed to the interaction between solute-solute molecules, while the high frequency relaxation is due to the reorientation of solvent molecules. The various dielectric and thermodynamic parameters were calculated such as the dielectric constant (εj), relaxation time (τj), effective dipole moment (μeff), Kirkwood correlation factor (g1), hydration number or the number of solvent molecules effectively bounded to solute molecule (Zib), effective volume of rotation (Veff), free energy of activation (ΔFj), entropy of activation (ΔSj) and enthalpy of activation (ΔHj). The static dielectric constant (ε1) shows increasing trend towards the higher concentration of asparagine, where as the high frequency dielectric constant (ε2) decreases with the concentration of asparagine. The relaxation time of low frequency (τ1) and high frequency (τ2) processes increases towards higher concentration of solute molecule and also towards lower temperature. As the concentration of asparagine increases, the value of effective dipole moment (μeff) decreases. With increasing amino acid concentrations hydration dynamics get affected and indicated by decreasing the hydration number (Zib) but the hydration dynamics of aqueous asparagine was found least temperature dependent.

Amino acid metabolism-related genes as potential biomarkers and the role of MATN3 in stomach adenocarcinoma: A bioinformatics, mendelian randomization and experimental validation study

BACKGROUND

Stomach adenocarcinoma (STAD) is a major contributor to cancer-related mortality worldwide. Alterations in amino acid metabolism, which is integral to protein synthesis, have been observed across various tumor types. However, the prognostic significance of amino acid metabolism-related genes in STAD remains underexplored.

METHODS

Transcriptomic gene expression and clinical data for STAD patients were obtained from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Amino acid metabolism-related gene sets were sourced from the Gene Set Enrichment Analysis (GSEA) database. A prognostic model was built using LASSO Cox regression based on the TCGA cohort and validated with GEO datasets (GSE84433, GSE84437, GSE84426). Kaplan-Meier analysis compared overall survival (OS) between high- and low-risk groups, and ROC curves assessed model accuracy. A nomogram predicted 1-, 3-, and 5-year survival. Copy number variations (CNVs) in model genes were visualized using data from the Xena platform, and mutation profiles were analyzed with "maftools" to create a waterfall plot. KEGG and GO enrichment analyses were performed to explore biological mechanisms. Immune infiltration and related functions were evaluated via ssGSEA, and Spearman correlation analyzed associations between risk scores and immune components. The TIDE database predicted immunotherapy efficacy, while FDA-approved drug sensitivity was assessed through CellMiner database. The role of MATN3 in STAD was further examined in vitro and in vivo, including amino acid-targeted metabolomic sequencing to assess its impact on metabolism. Finally, Mendelian randomization (MR) analysis evaluated the causal relationship between the model genes and gastric cancer.

RESULTS

In this study, we developed a prognostic risk model for STAD based on three amino acid metabolism-related genes (SERPINE1, NRP1, MATN3) using LASSO regression analysis. CNV amplification was common in SERPINE1 and NRP1, while CNV deletion frequently occurred in MATN3. STAD patients were classified into high- and low-risk groups based on the median risk score, with the high-risk group showing worse prognosis. A nomogram incorporating the risk score and clinical factors was created to estimate 1-, 3-, and 5-year survival rates. Distinct mutation profiles were observed between risk groups, with KEGG pathway analysis showing immune-related pathways enriched in the high-risk group. High-risk scores were significantly associated with the C6 (TGF-β dominant) subtype, while low-risk scores correlated with the C4 (lymphocyte-depleted) subtype. Higher risk scores also indicated increased immune infiltration, enhanced immune functions, lower tumor purity, and poorer immunotherapy response. Model genes were linked to anticancer drug sensitivity. Manipulating MATN3 expression showed that it promoted STAD cell proliferation and migration in vitro and tumor growth in vivo. Metabolomic sequencing revealed that MATN3 knockdown elevated levels of 30 amino acid metabolites, including alpha-aminobutyric acid, glycine, and aspartic acid, while reducing (S)-β-Aminoisobutyric acid and argininosuccinic acid. MR analysis found a significant causal effect of NRP1 on gastric cancer, but no causal relationship for MATN3 or SERPINE1.

CONCLUSION

In conclusion, the amino acid metabolism-related prognostic model shows promise as a valuable biomarker for predicting the clinical prognosis, selecting immunotherapy and drug treatment for STAD patients. Furthermore, our study has shed light on the potential value of the MATN3 as a promising strategy for combating the progression of STAD.

Rewiring Lysine Catabolism in Cancer Leads to Increased Histone Crotonylation and Immune Escape

Crotonyl-CoA (cr-CoA) is a metabolite derived directly from the catabolism of lysine (Lys) and tryptophan (Trp) or from the β-oxidation of fatty acids. In glioblastoma stem cells (GSCs), histone H4 crotonylation levels are significantly elevated, which appears to positively correlate with tumor growth. This increase in crotonyl-CoA production is attributed to the overexpression of specific Lys transporters on the cell membrane, leading to higher free lysine levels. Additionally, the overexpression of glutaryl-CoA dehydrogenase (GCDH), the enzyme responsible for crotonyl-CoA production, further contributes to this increase. When GCDH is depleted or under a lysine-restricted diet, genes involved in type I interferon (IFN) signaling are upregulated, resulting in tumor growth suppression. Type I interferons are a group of cytokines critical for antiviral responses and immunoregulation. This highlights how cancer cells exploit crotonylation to modulate the immune response. This work opens up new avenues for investigating how cancer cells rewire their metabolism to increase crotonylation and evade the immune system.

Targeting pivotal amino acids metabolism for treatment of leukemia

Metabolic reprogramming is a crucial characteristic of cancer, allowing cancer cells to acquire metabolic properties that support their survival, immune evasion, and uncontrolled proliferation. Consequently, targeting cancer metabolism has become an essential therapeutic strategy. Abnormal amino acid metabolism is not only a key aspect of metabolic reprogramming but also plays a significant role in chemotherapy resistance and immune evasion, particularly in leukemia. Changes in amino acid metabolism in tumor cells are typically driven by a combination of signaling pathways and transcription factors. Current approaches to targeting amino acid metabolism in leukemia include inhibiting amino acid transporters, blocking amino acid biosynthesis, and depleting specific amino acids to induce apoptosis in leukemic cells. Different types of leukemic cells rely on the exogenous supply of specific amino acids, such as asparagine, glutamine, arginine, and tryptophan. Therefore, disrupting the supply of these amino acids may represent a vulnerability in leukemia. This review focuses on the pivotal role of amino acids in leukemia metabolism, their impact on leukemic stem cells, and their therapeutic potential.

Clinical research framework proposal for ketogenic metabolic therapy in glioblastoma

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults, with a universally lethal prognosis despite maximal standard therapies. Here, we present a consensus treatment protocol based on the metabolic requirements of GBM cells for the two major fermentable fuels: glucose and glutamine. Glucose is a source of carbon and ATP synthesis for tumor growth through glycolysis, while glutamine provides nitrogen, carbon, and ATP synthesis through glutaminolysis. As no tumor can grow without anabolic substrates or energy, the simultaneous targeting of glycolysis and glutaminolysis is expected to reduce the proliferation of most if not all GBM cells. Ketogenic metabolic therapy (KMT) leverages diet-drug combinations that inhibit glycolysis, glutaminolysis, and growth signaling while shifting energy metabolism to therapeutic ketosis. The glucose-ketone index (GKI) is a standardized biomarker for assessing biological compliance, ideally via real-time monitoring. KMT aims to increase substrate competition and normalize the tumor microenvironment through GKI-adjusted ketogenic diets, calorie restriction, and fasting, while also targeting glycolytic and glutaminolytic flux using specific metabolic inhibitors. Non-fermentable fuels, such as ketone bodies, fatty acids, or lactate, are comparatively less efficient in supporting the long-term bioenergetic and biosynthetic demands of cancer cell proliferation. The proposed strategy may be implemented as a synergistic metabolic priming baseline in GBM as well as other tumors driven by glycolysis and glutaminolysis, regardless of their residual mitochondrial function. Suggested best practices are provided to guide future KMT research in metabolic oncology, offering a shared, evidence-driven framework for observational and interventional studies.

DON encapsulated carbon dot-vesicle conjugate in therapeutic intervention of lung adenocarcinoma by dual targeting of CD44 and SLC1A5

Lung adenocarcinoma, recognized as one of the most formidable malignancies with a dismal prognosis and low survival rates, poses a significant challenge in its treatment. This article delineates the design and development of a carbon dot-vesicle conjugate (HACD-TMAV) for efficient cytotoxicity towards lung cancer cells by target selective delivery of the glutamine inhibitor 6-diazo-5-oxo-L-norleucine (DON) within CD44-enriched A549 cancer cells. HACD-TMAV is composed of hyaluronic acid-based carbon dots (HACDs) and trimesic acid-based vesicles (TMAV), which are bound via electrostatic interactions. TMAVs are formed by positively charged trimesic acid-based amphiphiles through H-type aggregation in water. HACDs were synthesized through a one-step hydrothermal route. The blue-emitting HACD-TMAV conjugate demonstrated selective bioimaging in CD44-overexpressed A549 lung cancer cells due to specific ligand-receptor interactions between HA and CD44. HACD-TMAV exhibited notably improved DON loading efficiency compared to individual nano-vehicles. HACD-TMAV-DON exhibited remarkable (∼6.0-fold higher) cytotoxicity against CD44-overexpressing A549 cells compared to CD44- HepG2 cells and HEK 293 normal cells. Also, DON-loaded HACD-TMAV showed ∼2.0-fold higher cytotoxicity against A549 cells compared to individual carriers and ∼4.5-fold higher cytotoxicity than by DON. Furthermore, HACD-TMAV-DON induced a ∼3.5-fold reduction in the size of 3D tumor spheroids of A549 cells. The enhanced anticancer effectiveness was attributed to starvation of the A549 cells of glutamine by dual targeting of glutamine metabolism and solute linked carrier family 1 member A5 (SLC1A5) through HA-linked CD44-mediated targeted delivery of DON. This led to over-production of reactive oxygen species (ROS) that induced apoptosis of cancer cells through downregulation of the PI3K/AKT/mTOR signaling cascade.

The impact of epithelial-mesenchymal transition (EMT) induced by metabolic processes and intracellular signaling pathways on chemo-resistance, metastasis, and recurrence in solid tumors

The intricate cellular process, known as the epithelial-mesenchymal transition (EMT), significantly influences solid tumors development. Changes in cell shape, metabolism, and gene expression linked to EMT facilitate tumor cell invasion, metastasis, drug resistance, and recurrence. So, a better understanding of the intricate processes underlying EMT and its role in tumor growth may lead to the development of novel therapeutic approaches for the treatment of solid tumors. This review article focuses on the signals that promote EMT and metabolism, the intracellular signaling pathways leading to EMT, and the network of interactions between EMT and cancer cell metabolism. Furthermore, the functions of EMT in treatment resistance, recurrence, and metastasis of solid cancers are covered. Lastly, treatment approaches that focus on intracellular signaling networks and metabolic alterations brought on by EMT will be discussed.

Identification of Novel Target DCTPP1 for Colorectal Cancer Therapy with the Natural Small-Molecule Inhibitors Regulating Metabolic Reprogramming

Colorectal cancer (CRC) is one of the most common malignant tumors. Identification of new effective drug targets for CRC and exploration of bioactive small-molecules are clinically urgent. The human dCTP pyrophosphatase 1 (DCTPP1) is a newly identified pyrophosphatase regulating the cellular nucleotide pool but remains unexplored as potential target for CRC treatment. Here, twelve unprecedented chemical architectures terpene-nonadride heterodimers (1-12) and their monomers (13-20) were isolated from endophyte Bipolaris victoriae S27. Compounds 1-12 represented the first example of terpene-nonadride heterodimers, in which nonadride monomers of 1 and 2 were also first example of 5/6 bicyclic nonadrides. A series of assays showed that 2 could repress proliferation and induce cell cycle arrest, apoptotic and autophagic CRC cell death in vitro and in vivo. Clinical cancer samples data revealed that DCTPP1 was a novel target associated with poor survival in CRC. DCTPP1 was also identified as a new target protein of 2. Mechanically, compound 2 bound to DCTPP1, inhibited its enzymatic activity, intervened with amino acid metabolic reprogramming, and exerted anti-CRC activity. Our study demonstrates that DCTPP1 was a novel potential biomarker and therapeutic target for CRC, and 2 was the first natural anti-CRC drug candidate targeting DCTPP1.

Niche-Aware Metagenomic Screening for Enzyme Methioninase Illuminates Its Contribution to Metabolic Syntrophy

The single-step methioninase-mediated degradation of methionine (as a sulfur containing amino acid) is a reaction at the interface of carbon, nitrogen, sulfur, and methane metabolism in microbes. This enzyme also has therapeutic application due to its role in starving auxotrophic cancer cells. Applying our refined in silico screening pipeline on 33,469 publicly available genome assemblies and 1878 metagenome assembled genomes/single-cell amplified genomes from brackish waters of the Caspian Sea and the Fennoscandian Shield deep groundwater resulted in recovering 1845 methioninases. The majority of recovered methioninases belong to representatives of phyla Proteobacteria (50%), Firmicutes (29%), and Firmicutes_A (13%). Prevalence of methioninase among anaerobic microbes and in the anoxic deep groundwater together with the relevance of its products for energy conservation in anaerobic metabolism highlights such environments as desirable targets for screening novel methioninases and resolving its contribution to microbial metabolism and interactions. Among archaea, majority of detected methioninases are from representatives of Methanosarcina that are able to use methanethiol, the sulfur containing product from methionine degradation, as a precursor for methanogenesis. Branching just outside these archaeal methioninases in the phylogenetic tree, we recovered three methioninases belonging to representatives of Patescibacteria reconstructed from deep groundwater metagenomes. We hypothesize that methioninase in Patescibacteria could contribute to their syntrophic interactions where their methanogenic partners/hosts benefit from the produced 2-oxobutyrate and methanethiol. Our results underscore the significance of accounting for specific ecological niche in screening for enzyme variates with desired characteristics. Finally, complementing of our findings with experimental validation of methioninase activity confirms the potential of our in silico screening in clarifying the peculiar ecological role of methioninase in anoxic environments.

Arginine deprivation/citrulline augmentation with ADI-PEG20 as novel therapy for complications in type 2 diabetes

OBJECTIVE

Chronic inflammation and oxidative stress mediate the pathological progression of diabetic complications, like diabetic retinopathy (DR), peripheral neuropathy (DPN) and impaired wound healing. Studies have shown that treatment with a stable form of arginase 1 that reduces l-arginine levels and increases ornithine and urea limits retinal injury and improves visual function in DR. We tested the therapeutic efficacy of PEGylated arginine deiminase (ADI-PEG20) that depletes l-arginine and elevates l-citrulline on diabetic complications in the db/db mouse model of type 2 diabetes (T2D).

METHODS

Mice received intraperitoneal (IP), intramuscular (IM), or intravitreal (IVT) injections of ADI-PEG20 or PEG20 as control. Effects on body weight, fasting blood glucose levels, blood-retinal-barrier (BRB) function, visual acuity, contrast sensitivity, thermal sensitivity, and wound healing were determined. Studies using bone marrow-derived macrophages (BMDM) examined the underlying signaling pathway.

RESULTS

Systemic injections of ADI-PEG20 reduced body weight and blood glucose and decreased oxidative stress and inflammation in db/db retinas. These changes were associated with improved BRB and visual function along with thermal sensitivity and wound healing. IVT injections of either ADI-PEG20, anti-VEGF antibody or their combination also improved BRB and visual function. ADI-PEG20 treatment also prevented LPS/IFNℽ-induced activation of BMDM in vitro as did depletion of l-arginine and elevation of l-citrulline.

CONCLUSIONS/INTERPRETATION

ADI-PEG20 treatment limited signs of DR and DPN and enhanced wound healing in db/db mice. Studies using BMDM suggest that the anti-inflammatory effects of ADI-PEG20 involve blockade of the JAK2-STAT1 signaling pathway via l-arginine depletion and l-citrulline production.

Transport of aromatic amino acids l-tryptophan, l-tyrosine, and l-phenylalanine by the organic anion transporting polypeptide (OATP) 3A1

Amino acids are important for cellular metabolism. Their uptake across the plasma membrane is mediated by transport proteins. Despite the fact that the organic anion transporting polypeptide 4C1 (OATP4C1, Uniprot: Q6ZQN7) mediates transport of l-arginine and l-arginine derivatives, other members of the OATP family have not been characterized as amino acid transporters. The OATP family member OATP3A1 (gene symbol SLCO3A1, Uniprot: Q9UIG8) is ubiquitously expressed in human cells and highly expressed in many cancer tissues and cell lines. However, only a few substrates are known for OATP3A1. Accordingly, knowledge about its biological relevance is restricted. Our aim was to identify new substrates of OATP3A1 to gain insights into its (patho-)physiological function. In an LC-MS-based untargeted metabolomics assay using untreated OATP3A1-overexpressing HEK293 cells and control cells, we identified several amino acids as potential substrates of OATP3A1. Subsequent uptake experiments using exogenously added substrates revealed OATP3A1-mediated transport of l-tryptophan, l-tyrosine, and l-phenylalanine with 194.8 ± 28.7% (P < 0.05), 226.2 ± 18.7% (P < 0.001), and 235.2 ± 13.5% (P < 0.001), respectively, in OATP3A1-overexpressing cells compared to control cells. Furthermore, kinetic transport parameters (Km values) were determined (Trp = 61.5 ± 14.2 μm, Tyr = 220.8 ± 54.5 μm, Phe = 234.7 ± 20.6 μm). In summary, we identified the amino acids l-tryptophan, l-tyrosine, and l-phenylalanine as new substrates of OATP3A1. These findings could be used for a better understanding of (patho-)physiological processes involving increased demand of amino acids, where OATP3A1 should be considered as an important uptake transporter of l-tryptophan, l-tyrosine, and l-phenylalanine.

NRF2 signaling and amino acid metabolism in cancer

Alterations in amino acid metabolism have emerged as a critical component in cancer biology, influencing various aspects of tumor initiation, progression, and metastasis. This review explores how amino acids, beyond their role as protein building blocks, are essential for redox balance, cell proliferation, metastasis, signaling/epigenetic regulation, and tumor microenvironment modulation in cancer. We particularly focus on the intricate relationship between amino acid metabolism and nuclear factor erythroid 2-related factor 2 (NRF2) signaling, a master regulator of oxidative stress response that frequently hyperactivated in cancer. Increasing evidence indicates that NRF2 is a key player in amino acid metabolism, orchestrating metabolism of cysteine, glutamine, and serine/glycine to promote cancer cell survival and growth. This comprehensive analysis provides insights into potential therapeutic strategies targeting the NRF2-amino acid metabolism axis, offering new avenues for cancer treatment that address multiple aspects of tumor biology.

Predictive nomogram of the clinical outcomes of colorectal cancer based on methylated SEPT9 and intratumoral IL-10+ Tregs infiltration

BACKGROUND

Gene methylation and the immune-related tumor microenvironment (TME) are highly correlated in tumor progression and therapeutic efficacy. Although both of them can be used to predict the clinical outcomes of colorectal cancer (CRC) patients, their predictive value is still unsatisfactory. Whether a combination risk model comprising these two prediction parameters performs better predictive effectiveness than independent factor is still unclear. Methylated Septin9 (mSEPT9) is an early diagnosis biomarker of CRC, in this study, we aimed to investigate mSEPT9-related biomarkers of immunosuppressive TME and identify the value of the combination risk model in predicting the clinical outcomes of CRC.

METHODS

Immunofluorescence staining was performed to clarify the correlation between intratumoral IL-10+ Treg infiltration and mSEPT9 in peripheral blood. Survival time, response to 5-fluorouracil (5-FU)-based chemotherapy and PD-1 blockade, and the probability of recurrence or metastasis were analyzed in study (197 CRC samples) and validation (195 CRC samples) sets to evaluate the efficacy of combination risk model. Potential mechanisms were explored by mRNA sequencing.

RESULTS

Hypermethylated SEPT9 in the peripheral blood of patients with CRC (stage I-III, and stage IV with resectable M1) before radical resection was positively correlated with high intratumoral IL-10+ Treg infiltration. The high-risk model revealed poor overall survival and progression-free survival, inferior therapeutic response to 5-FU-based chemotherapy and PD-1 blockade, and high probability of recurrence or metastasis. The underlying mechanisms may be associated with the increase in mSEPT9 and mediation of IL-10 via methionine metabolic reprogramming-induced infiltration of IL-10+ Tregs in the TME, which promotes tumor progression and resistance to 5-FU-based chemotherapy and PD-1 blockade.

CONCLUSIONS

The combination risk model of peripheral mSETP9 and intratumoral IL-10+ Treg infiltration in CRC can effectively predict prognosis, responsiveness to 5-FU-based chemotherapy and PD-1 blockade, and the probability of recurrence or metastasis. Therefore, this model can be used for precision treatment of CRC.

Altered metabolism in cancer: insights into energy pathways and therapeutic targets

Cancer cells undergo significant metabolic reprogramming to support their rapid growth and survival. This study examines important metabolic pathways like glycolysis, oxidative phosphorylation, glutaminolysis, and lipid metabolism, focusing on how they are regulated and their contributions to the development of tumors. The interplay between oncogenes, tumor suppressors, epigenetic modifications, and the tumor microenvironment in modulating these pathways is examined. Furthermore, we discuss the therapeutic potential of targeting cancer metabolism, presenting inhibitors of glycolysis, glutaminolysis, the TCA cycle, fatty acid oxidation, LDH, and glucose transport, alongside emerging strategies targeting oxidative phosphorylation and lipid synthesis. Despite the promise, challenges such as metabolic plasticity and the need for combination therapies and robust biomarkers persist, underscoring the necessity for continued research in this dynamic field.

Pre-analytic decrease of phenylalanine in plasma of patients with phenylketonuria treated with pegvaliase

Treatment of phenylketonuria (PKU) has evolved since the initial introduction of a phenylalanine (Phe) restricted diet. The most recent option for adults affected with PKU is treatment with an alternate enzyme, phenylalanine ammonia lyase (PAL), that metabolizes excess Phe. Proper management of all patients with PKU relies on accurate measurement of Phe levels in blood, to comply with guidance intended to minimize the neurological symptoms. Recently, our laboratory was notified of discrepant results for a patient with PKU who is treated with pegvaliase. Two specimens were collected at the same time but yielded unexpectedly different Phe concentrations. After exclusion of specimen mix-ups or analytical errors, we suspected that there was residual pegvaliase activity in the specimens continuing to degrade Phe after collection. To investigate this possibility, we performed spiking studies that showed the degradation of Phe over time at ambient temperatures. Sample preparation by protein crash appears to deactivate pegvaliase and prevents further Phe degradation. However, because pegvaliase deactivation would be required immediately following blood collection, appropriate mitigation measures must be implemented, including stringent pre-analytical requirements, alternate sample matrices such as dried blood spots, or point of care testing. Until then, health care professionals need to be cautious in their interpretation of Phe levels in their patients with PKU that are treated with pegvaliase.

O-GlcNAcylation in tumorigenesis and its implications for cancer therapy

O-linked N-acetylglucosaminylation (O-GlcNAcylation) is a dynamic and reversible posttranslational modification that targets serine and threonine residues in a variety of proteins. Uridine diphospho-N-acetylglucosamine, which is synthesized from glucose via the hexosamine biosynthesis pathway, is the major donor of this modification. O-GlcNAc transferase is the sole enzyme that transfers GlcNAc onto protein substrates, while O-GlcNAcase is responsible for removing this modification. O-GlcNAcylation plays an important role in tumorigenesis and progression through the modification of specific protein substrates. In this review, we discuss the tumor-related biological functions of O-GlcNAcylation and summarize the recent progress in the development of pharmaceutical options to manipulate the O-GlcNAcylation of specific proteins as potential anticancer therapies.

Iron(III)-salophene catalyzes redox cycles that induce phospholipid peroxidation and deplete cancer cells of ferroptosis-protecting cofactors

Ferroptosis, a lipid peroxidation-driven cell death program kept in check by glutathione peroxidase 4 and endogenous redox cycles, promises access to novel strategies for treating therapy-resistant cancers. Chlorido [N,N'-disalicylidene-1,2-phenylenediamine]iron (III) complexes (SCs) have potent anti-cancer properties by inducing ferroptosis, apoptosis, or necroptosis through still poorly understood molecular mechanisms. Here, we show that SCs preferentially induce ferroptosis over other cell death programs in triple-negative breast cancer cells (LC50 ≥ 0.07 μM) and are particularly effective against cell lines with acquired invasiveness, chemo- or radioresistance. Redox lipidomics reveals that initiation of cell death is associated with extensive (hydroper)oxidation of arachidonic acid and adrenic acid in membrane phospholipids, specifically phosphatidylethanolamines and phosphatidylinositols, with SCs outperforming established ferroptosis inducers. Mechanistically, SCs effectively catalyze one-electron transfer reactions, likely via a redox cycle involving the reduction of Fe(III) to Fe(II) species and reversible formation of oxo-bridged dimeric complexes, as supported by cyclic voltammetry. As a result, SCs can use hydrogen peroxide to generate organic radicals but not hydroxyl radicals and oxidize membrane phospholipids and (membrane-)protective factors such as NADPH, which is depleted from cells. We conclude that SCs catalyze specific redox reactions that drive membrane peroxidation while interfering with the ability of cells, including therapy-resistant cancer cells, to detoxify phospholipid hydroperoxides.

Immunotherapy and the ovarian cancer microenvironment: Exploring potential strategies for enhanced treatment efficacy

Despite progress in cancer immunotherapy, ovarian cancer (OC) prognosis continues to be disappointing. Recent studies have shed light on how not just tumour cells, but also the complex tumour microenvironment, contribute to this unfavourable outcome of OC immunotherapy. The complexities of the immune microenvironment categorize OC as a 'cold tumour'. Nonetheless, understanding the precise mechanisms through which the microenvironment influences the effectiveness of OC immunotherapy remains an ongoing scientific endeavour. This review primarily aims to dissect the inherent characteristics and behaviours of diverse cells within the immune microenvironment, along with an exploration into its reprogramming and metabolic changes. It is expected that these insights will elucidate the operational dynamics of the immune microenvironment in OC and lay a theoretical groundwork for improving the efficacy of immunotherapy in OC management.

Construction and validation of a prognostic model for overall survival time of patients with ovarian cancer by metabolism-related genes

BACKGROUND

Ovarian cancer is a female-specific malignancy with high morbidity and mortality. The metabolic reprogramming of tumor cells is closely related to the biological behavior of tumors.

METHODS

The prognostic signature of the metabolism-related gene (MRGs) was established by LASSO-Cox regression analysis. The prognostic signature of MRGs was also prognosticated in each clinical subgroup. These genes were subjected to functional enrichment analysis and tissue expression exploration. Analysis of the MRG prognostic signature in terms of immune cell infiltration and antitumor drug susceptibility was also performed.

RESULTS

A MRG prognostic signature including 21 genes was established and validated. Most of the 21 MRGs were expressed at different levels in ovarian cancer than in normal ovarian tissue. The enrichment analysis suggested that MRGs were involved in lipid metabolism, membrane organization, and molecular binding. The MRG prognostic signature demonstrated the predictive value of overall survival time in various clinical subgroups. The monocyte, NKT, Tgd and Tex cell scores showed differences between the groups with high- and low-risk score. The antineoplastic drug analysis we performed provided information on ovarian cancer drug therapy and drug resistance. In vitro experiments verified that PLCH1 in 21 MRGs can regulate the apoptosis and proliferation of ovarian cancer cells.

CONCLUSION

This metabolism-related prognostic signature was a potential prognostic factor in patients with ovarian cancer, demonstrating high stability and accuracy.

Regulatory mechanisms of amino acids in ferroptosis

Ferroptosis, an iron-dependent non-apoptotic regulated cell death process, is associated with the pathogenesis of various diseases. Amino acids, which are indispensable substrates of vital activities, significantly regulate ferroptosis. Amino acid metabolism is involved in maintaining iron and lipid homeostasis and redox balance. The regulatory effects of amino acids on ferroptosis are complex. An amino acid may exert contrasting effects on ferroptosis depending on the context. This review systematically and comprehensively summarized the distinct roles of amino acids in regulating ferroptosis and highlighted the emerging opportunities to develop clinical therapeutic strategies targeting amino acid-mediated ferroptosis.

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.

Opportunities for nanomaterials in enzyme therapy

In recent years, enzyme therapy strategies have rapidly evolved to catalyze essential biochemical reactions with therapeutic potential. These approaches hold particular promise in addressing rare genetic disorders, cancer treatment, neurodegenerative conditions, wound healing, inflammation management, and infectious disease control, among others. There are several primary reasons for the utilization of enzymes as therapeutics: their substrate specificity, their biological compatibility, and their ability to generate a high number of product molecules per enzyme unit. These features have encouraged their application in enzyme replacement therapy where the enzyme serves as the therapeutic agent to rectify abnormal metabolic and physiological processes, enzyme prodrug therapy where the enzyme initiates a clinical effect by activating prodrugs, and enzyme dynamic or starving therapy where the enzyme acts upon host substrate molecules. Currently, there are >20 commercialized products based on therapeutic enzymes, but approval rates are considerably lower than other biologicals. This has stimulated nanobiotechnology in the last years to develop nanoparticle-based solutions that integrate therapeutic enzymes. This approach aims to enhance stability, prevent rapid clearance, reduce immunogenicity, and even enable spatio-temporal activation of the therapeutic catalyst. This comprehensive review delves into emerging trends in the application of therapeutic enzymes, with a particular emphasis on the synergistic opportunities presented by incorporating enzymes into nanomaterials. Such integration holds the promise of enhancing existing therapies or even paving the way for innovative nanotherapeutic approaches.

Enzalutamide Sensitizes Castration-Resistant Prostate Cancer to Copper-Mediated Cell Death

Despite the initial efficacy of enzalutamide in castration-resistant prostate cancer (CRPC), inevitable resistance remains a significant challenge. Here, the synergistic induction of copper-dependent cell death (cuproptosis) in CRPC cells is reported by enzalutamide and copper ionophores (elesclomol/disulfiram). Mechanistically, enzalutamide treatment increases mitochondrial dependence in CRPC cells, rendering them susceptible to cuproptosis, as evidenced by specific reversal with the copper chelator tetrathiomolybdate. This susceptibility is characterized by hallmarks of cuproptosis, including lipoylated protein aggregation and iron-sulfur cluster protein instability. Interestingly, the mitochondrial matrix reductase, FDX1, specifically correlates with elesclomol sensitivity, suggesting a potential mechanistic divergence between the two copper ionophores. Notably, this synergistic effect extends beyond in vitro models, demonstrating efficacy in 22Rv1 xenografts, mouse Pten p53 knockout organoids. Importantly, enzalutamide significantly enhances copper ionophore-mediated cytotoxicity in enzalutamide-resistant cells. Collectively, these findings indicate that enzalutamide and copper ionophores synergistically induce cuproptosis, offering a promising therapeutic avenue for CRPC, potentially including enzalutamide-resistant cases.

Starving cancer cells to enhances DNA damage and immunotherapy response

Prostate cancer (PCa) poses significant challenges in treatment, particularly when it progresses to a metastatic, castrate-resistant state. Conventional therapies, including chemotherapy, radiotherapy, and hormonal treatments, often fail due to toxicities, off-target effects, and acquired resistance. This research perspective defines an alternative therapeutic strategy focusing on the metabolic vulnerabilities of PCa cells, specifically their reliance on non-essential amino acids such as cysteine. Using an engineered enzyme cyst(e)inase to deplete the cysteine/cystine can induce oxidative stress and DNA damage in cancer cells. This depletion elevates reactive oxygen species (ROS) levels, disrupts glutathione synthesis, and enhances DNA damage, leading to cancer cell death. The combinatorial use of cyst(e)inase with agents targeting antioxidant defenses, such as thioredoxins, further amplifies ROS accumulation and cytotoxicity in PCa cells. Overall, in this perspective provides a compressive overview of the previous work on manipulating amino acid metabolism and redox balance modulate the efficacy of DNA repair-targeted and immune checkpoint blockade therapies in prostate cancer.

The Improved Antineoplastic Activity of Thermophilic L-Asparaginase Tli10209 via Site-Directed Mutagenesis

Amino acid deprivation therapy (AADT) is a novel anticancer therapy, considered nontoxic and selective. Thermophilic L-asparaginase enzymes display high stability and activity at elevated temperatures. However, they are of limited use in clinical applications because of their low substrate affinity and reduced activity under physiological conditions, which may necessitate an improved dosage, leading to side effects and greater costs. Thus, in an attempt to improve the activity of L-Asn at 37 °C, with the use of a semi-rational design, eight active-site mutants of Thermococcus litoralis DSM 5473 L-asparaginase Tli10209 were developed. T70A exhibited a 5.11-fold increase compared with the wild enzyme in physiological conditions. Double-mutant enzymes were created by combining mutants with higher hydrolysis activity. T70A/F36Y, T70A/K48L, and T70A/D50G were enhanced by 5.59-, 6.38-, and 5.58-fold. The immobilized enzyme applied in MCF-7 breast cancer cells only required one-seventh of the dose of the free enzyme to achieve the same inhibition rate under near-infrared irradiation. This provides a proof of concept that it is possible to reduce the consumption of L-Asn by improving its activity, thus providing a method to manage side effects.

PEGylated Recombinant Aplysia punctata Ink Toxin Depletes Arginine and Lysine and Inhibits the Growth of Tumor Xenografts

In recent years, a novel treatment method for cancer has emerged, which is based on the starvation of tumors of amino acids like arginine. The deprivation of arginine in serum is based on enzymatic degradation and can be realized by arginine deaminases like the l-amino acid oxidase found in the ink toxin of the sea hare Aplysia punctata. Previously isolated from the ink, the l-amino acid oxidase was described to oxidate the essential amino acids l-lysine and l-arginine to their corresponding deaminated alpha-keto acids. Here, we present the recombinant production and functionalization of the amino acid oxidase Aplysia punctata ink toxin (APIT). PEGylated APIT (APIT-PEG) increased the blood circulation time. APIT-PEG treatment of patient-derived xenografted mice shows a significant dose-dependent reduction of tumor growth over time mediated by amino acid starvation of the tumor. Treatment of mice with APIT-PEG, which led to deprivation of arginine, was well tolerated.

The multifaceted roles of small extracellular vesicles in metabolic reprogramming in the tumor microenvironments

The link between metabolism and tumor progression has been extensively researched for a long time. With the increasing number of studies uncovering the multiple functions of metabolic reprogramming in tumor microenvironments, the regulatory network seems to become even more intricate at the same time. Small extracellular vesicles (sEV), as crucial mediators facilitating intercellular communications, exhibit significant involvement in regulating metabolic reprogramming within the complicated network of tumor microenvironments. sEV derived from tumor cells and those released by other cell populations such as tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs) can mutually influence each other, giving rise to diverse complex feedback loops. This review includes multiple studies conducted in recent years to summarize the functions of sEV in altering metabolism in various cell types within tumor microenvironments. Additionally, it aims to highlight potential therapeutic targets based on the commonly observed mechanisms identified in different studies.

Glutathione-depleting Liposome Adjuvant for Augmenting the Efficacy of a Glutathione Covalent Inhibitor Oridonin for Acute Myeloid Leukemia Therapy

BACKGROUND

Discrepancies in the utilization of reactive oxygen species (ROS) between cancer cells and their normal counterparts constitute a pivotal juncture for the precise treatment of cancer, delineating a noteworthy trajectory in the field of targeted therapies. This phenomenon is particularly conspicuous in the domain of nano-drug precision treatment. Despite substantial strides in employing nanoparticles to disrupt ROS for cancer therapy, current strategies continue to grapple with challenges pertaining to efficacy and specificity. One of the primary hurdles lies in the elevated levels of intracellular glutathione (GSH). Presently, predominant methods to mitigate intracellular GSH involve inhibiting its synthesis or promoting GSH efflux. However, a conspicuous gap remains in the absence of a strategy capable of directly and efficiently clearing GSH.

METHODS

We initially elucidated the chemical mechanism underpinning oridonin, a diminutive pharmacological agent demonstrated to perturb reactive oxygen species, through its covalent interaction with glutathione. Subsequently, we employed the incorporation of maleimide-liposomes, renowned for their capacity to disrupt the ROS delivery system, to ameliorate the drug's water solubility and pharmacokinetics, thereby enhancing its ROS-disruptive efficacy. In a pursuit to further refine the targeting for acute myeloid leukemia (AML), we harnessed the maleic imide and thiol reaction mechanism, facilitating the coupling of Toll-like receptor 2 (TLR2) peptides to the liposomes' surface via maleic imide. This strategic approach offers a novel method for the precise removal of GSH, and its enhancement endeavors are directed towards fortifying the precision and efficacy of the drug's impact on AML targets.

RESULTS

We demonstrated that this peptide-liposome-small molecule machinery targets AML and consequently induces cell apoptosis both in vitro and in vivo through three disparate mechanisms: (I) Oridonin, as a Michael acceptor molecule, inhibits GSH function through covalent bonding, triggering an initial imbalance of oxidative stress. (II) Maleimide further induces GSH exhaustion, aggravating redox imbalance as a complementary augment with oridonin. (III) Peptide targets TLR2, enhances the directivity and enrichment of oridonin within AML cells.

CONCLUSION

The rationally designed nanocomplex provides a ROS drug enhancement and targeted delivery platform, representing a potential solution by disrupting redox balance for AML therapy.

Influence of Amino Acids and Exercise on Muscle Protein Turnover, Particularly in Cancer Cachexia

Cancer cachexia is a multifaceted syndrome that impacts individuals with advanced cancer. It causes numerous pathological changes in cancer patients, such as inflammation and metabolic dysfunction, which further diminish their quality of life. Unfortunately, cancer cachexia also increases the risk of mortality in affected individuals, making it an important area of focus for cancer research and treatment. Several potential nutritional therapies are being tested in preclinical and clinical models for their efficacy in improving muscle metabolism in cancer patients. Despite promising results, no special nutritional therapies have yet been validated in clinical practice. Multiple studies provide evidence of the benefits of increasing muscle protein synthesis through an increased intake of amino acids or protein. There is also increasing evidence that exercise can reduce muscle atrophy by modulating protein synthesis. Therefore, the combination of protein intake and exercise may be more effective in improving cancer cachexia. This review provides an overview of the preclinical and clinical approaches for the use of amino acids with and without exercise therapy to improve muscle metabolism in cachexia.

NIR-II imaging-guided precise photodynamic therapy for augmenting tumor-starvation therapy by glucose metabolism reprogramming interference

Metabolic reprogramming is a mechanism by which cancer cells alter their metabolic patterns to promote cell proliferation and growth, thereby enabling their resistance to external stress. 2-Deoxy-D-glucose (2DG) can eliminate their energy source by inhibiting glucose glycolysis, leading to cancer cell death through starvation. However, a compensatory increase in mitochondrial metabolism inhibits its efficacy. Herein, we propose a synergistic approach that combines photodynamic therapy (PDT) with starvation therapy to address this challenge. To monitor the nanodrugs and determine the optimal triggering time for precise tumor therapy, a multifunctional nano-platform comprising lanthanide-doped nanoparticle (LnNP) cores was constructed and combined with mesoporous silicon shells loaded with 2DG and photosensitizer chlorin e6 (Ce6) in the mesopore channels. Under 980 nm near-infrared light excitation, the downshifted 1550 nm fluorescence signal in the second near-infrared (NIR-II, 1000-1700 nm) window from the LnNPs was used to monitor the accumulation of nanomaterials in tumors. Furthermore, upconverted 650 nm light excited the Ce6 to generate singlet oxygen for PDT, which damaged mitochondrial function and enhanced the efficacy of 2DG by inhibiting hexokinase 2 and lactate dehydrogenase A expressions. As a result, glucose metabolism reprogramming was inhibited and the efficiency of starvation therapy was significantly enhanced. Overall, the proposed NIR-II bioimaging-guided PDT-augmented starvation therapy, which simultaneously inhibited glycolysis and mitochondria, facilitated the effects of a cancer theranostic system.

METTL16 deficiency attenuates apoptosis through translational control of extrinsic death receptor during nutrient deprivation

METTL16 is a well-characterized m6A methyltransferase that has been reported to contribute to tumorigenesis in various types of cancer. However, the effect of METTL16 on tumor progression under restricted nutrient conditions, which commonly occur in tumor microenvironment, has yet to be elucidated. Herein, our study initially reported the inhibitory effect of METTL16 depletion on apoptosis under amino acid starvation conditions. Mechanistically, we determined that the METTL16 knockdown represses the expression of extrinsic death receptors at both transcription and translation levels. Depletion of METTL16 prevented protein synthesis of GCN2, resulting in diminished ATF4 expression in a GCN2-eIF2α-dependent manner. Reduction of ATF4 further declined the expression of apoptotic receptor protein DR5. Meanwhile, METTL16 deficiency directly hampered protein synthesis of FADD and DR5, thereby impairing apoptosis and promoting cancer cell survival. Taken together, our study provides novel evidence for the involvement of METTL16 in regulating cancer progression, suggesting that METTL16 as a potential therapeutic target for cancer treatment.