Targeting amino acid metabolism for cancer therapy

From natural herbal wisdom to nano innovation: Revolutionizing tumor treatment through intervening in metabolic reprogramming

In recent years, with the deepening understanding of the biological mechanisms underlying tumorigenesis, metabolic reprogramming has emerged as a pivotal process in cancer initiation, progression, and treatment resistance, gradually paving the way for new avenues in precision oncology. Natural herbal ingredients, characterized by their multi-target engagement, low toxicity, and wide-ranging biological activities, exhibit unique advantages in anti-cancer therapy. Nonetheless, the clinical application of these components has been constrained by issues such as poor solubility, low bioavailability, and inadequate stability when administered through traditional delivery methods. The advent of multifunctional nanoformulations has offered solutions to these challenges, substantially advancing the utilization of natural herbal components in precision therapy targeting tumor metabolic reprogramming. This article provides a comprehensive review of the multidimensional features of cancer metabolic reprogramming and its intricate regulatory network, highlighting the latest advancements in metabolic regulation, targeted delivery, and precision therapy achieved through natural herbs and their multifunctional nanomedicines. It also offers insights into future directions in this field. We are justified in believing that continued breakthroughs in this area will usher in safer and more effective treatment options for cancer patients, heralding a new chapter in cancer therapy.

Combination of Metabolomics and Bioinformatics to Reveal the Mechanism of Luteolin in the Treatment of Cervical Cancer

The incidence of cervical cancer is high among women globally. The potential therapeutic efficacy of luteolin in the treatment of cervical cancer has been identified. Therefore, we aim to elucidate the mechanism of action of luteolin in the treatment of cervical cancer through a comprehensive approach that integrates metabolomics with bioinformatics. The first step involved the identification of differential metabolites through UHPLC-Q-Orbitrap-MS, which were then utilized for enrichment analysis of metabolic pathways and to determine the targets associated with these differential metabolites. Subsequently, the differential analysis and WGCNA were employed to identify DEGs and functional module genes respectively. The common targets were obtained by intersecting the results from the aforementioned three analyses, followed by conducting GO and KEGG pathway enrichment analysis on these targets. Subsequently, PPI networks were constructed using these common targets, and key targets were identified utilizing the MCC, EPC, Degree, Closeness Centrality, Betweenness Centrality, and Bottleneck algorithms in the CytoHubba plug-in. The subsequent steps involved the analysis of key genes for constructing a nomogram, conducting a ROC curve, examining content expression and survival analysis, and ultimately employing molecular docking to investigate the interaction between luteolin and crucial targets. The metabolomics analysis revealed the identification of a total of 45 distinct metabolites in this study, primarily associated with amino acid and nucleotide metabolism. The intersection of 773 differential metabolite targets, 3493 cervical cancer differential genes, and 3245 WGCNA-associated module genes yielded a set of 32 target genes associated with luteolin therapy for cervical cancer. The GO and KEGG pathway enrichment analysis also revealed that these targets were primarily associated with amino acid metabolism and nucleotide metabolism. The CytoHubba plug-in was utilized to identify three key genes (DMNT1, EZH2, and GMPS) through the application of multiple algorithms. Additionally, the datasets GSE63514, GSE67522, and GEPIA2 revealed a significant upregulation of all three genes in tumor tissue. ROC analysis demonstrated the good predictive ability of these three hub genes. Finally, the molecular docking results demonstrated the high binding affinity of luteolin towards DMNT1, EZH2, and GMPS. In conclusion, this study has unveiled the potential of luteolin in modulating amino acid and nucleotide metabolism for the treatment of cervical cancer, thereby providing a theoretical foundation for further investigation into the intricate association between luteolin and cervical cancer.

Global Trends in Research of Amino Acid Metabolism in T Lymphocytes in Recent 15 Years: A Bibliometric Analysis

Amino acid metabolism in T cells determines the therapeutic efficacy of T-cell-targeting drugs. To assess the direction of amino acid metabolism in T cells and construct related knowledge structure, we performed a bibliometric analysis aiming at amino acid metabolism in T cells utilizing studies publicized in recent 15 years. Three hundred thirty-seven related studies were downloaded from the Web of Science Core Collection (WoSCC), and the information on countries, institutes, and authors was collected and analyzed. In addition, the present research status and future trends were explored according to the results yielded from the analysis of cited references and keywords. This study revealed that publications regarding amino acid metabolism in T cells gradually increased each year. The USA is the top producer and most influential country in this field. Recent research has focused on the correlation between the metabolism of several amino acids and regulatory T cells (Tregs) and CD8+ T cells. Overall, this research offers a comprehensive exhibition on the field of amino acid metabolism in T cells, which will help researchers to study this domain more effectively and intuitively.

Metabolic Reprogramming in Cancer: Implications for Immunosuppressive Microenvironment

Cancer is a complex and heterogeneous disease characterised by uncontrolled cell growth and proliferation. One hallmark of cancer cells is their ability to undergo metabolic reprogramming, which allows them to sustain their rapid growth and survival. This metabolic reprogramming creates an immunosuppressive microenvironment that facilitates tumour progression and evasion of the immune system. In this article, we review the mechanisms underlying metabolic reprogramming in cancer cells and discuss how these metabolic alterations contribute to the establishment of an immunosuppressive microenvironment. We also explore potential therapeutic strategies targeting metabolic vulnerabilities in cancer cells to enhance immune-mediated anti-tumour responses. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02044861, NCT03163667, NCT04265534, NCT02071927, NCT02903914, NCT03314935, NCT03361228, NCT03048500, NCT03311308, NCT03800602, NCT04414540, NCT02771626, NCT03994744, NCT03229278, NCT04899921.

Metabolism of cancer cells and immune cells in the initiation, progression, and metastasis of cancer

The metabolism of cancer and immune cells plays a crucial role in the initiation, progression, and metastasis of cancer. Cancer cells often undergo metabolic reprogramming to sustain their rapid growth and proliferation, along with meeting their energy demands and biosynthetic needs. Nevertheless, immune cells execute their immune response functions through the specific metabolic pathways, either to recognize, attack, and eliminate cancer cells or to promote the growth or metastasis of cancer cells. The alteration of cancer niches will impact the metabolism of both cancer and immune cells, modulating the survival and proliferation of cancer cells, and the activation and efficacy of immune cells. This review systematically describes the key characteristics of cancer cell metabolism and elucidates how such metabolic traits influence the metabolic behavior of immune cells. Moreover, this article also highlights the crucial role of immune cell metabolism in anti-tumor immune responses, particularly in priming T cell activation and function. By comprehensively exploring the metabolic crosstalk between cancer and immune cells in cancer niche, the aim is to discover novel strategies of cancer immunotherapy and provide effective guidance for clinical research in cancer treatment. In addition, the review also discusses current challenges such as the inadequacy of relevant diagnostic technologies and the issue of multidrug resistance, and proposes potential solutions including bolstering foundational cancer research, fostering technological innovation, and implementing precision medicine approaches. In-depth research into the metabolic effects of cancer niches can improve cancer treatment outcomes, prolong patients' survival period and enhance their quality of life.

Multi-Omics Assessment of Puff Volume-Mediated Salivary Biomarkers of Metal Exposure and Oxidative Injury Associated with Electronic Nicotine Delivery Systems

BACKGROUND

Since their inception, electronic nicotine delivery systems (ENDS) have gained increasing popularity, sparking a vaping epidemic among adolescents in the US and globally. Several ENDS safety concerns have emerged as device features and formats that contribute to heavy metal exposure and toxicity continue to evolve and outpace regulatory efforts.

OBJECTIVES

Our objective was to integrate ENDS emission profiles with salivary proteome and metabolome data to characterize exposure factors that may influence adverse vaping-mediated health outcomes.

METHODS

A total of 56 participants (38 exclusive ENDS users and 18 non-ENDS users) were recruited. A subset of 15 exclusive ENDS users completed puffing topography assessments to obtain individual vaping behavior patterns using each participant's ENDS device. Inductively coupled plasma mass spectrometry was used to determine the metal content of emissions (12 ENDS devices) generated using a programmable ENDS aerosol generation system and saliva (15 exclusive ENDS users and 5 non-ENDS users). Saliva samples from 10 exclusive ENDS users and 5 non-ENDS users were analyzed for proteomic, metabolomic, inflammatory, and oxidative stress/damage biomarkers.

RESULTS

A linear puff volume-dependent increase in particle emissions and heavy metals was observed in ENDS aerosols and saliva of exclusive ENDS users. Elevated puff volume-dependent levels of salivary cytokines, including tumor necrosis factor-alpha (TNFα ), interleukin-1 beta (IL-1β ), and IL-6, were observed alongside the oxidative damage indicators malondialdehyde (MDA), superoxide dismutase (SOD), and 8-hydroxy-2'-deoxyguanosine (8-OHdG). Proteome-metabolome network analysis showed a higher risk of potentially developing neurological and respiratory diseases in ENDS users compared with non-ENDS users. Integrated salivary proteome-metabolome-metallome network analysis further demonstrated that heavy metals were associated with proteomic and metabolomic perturbations, with notable alterations in inflammatory response, immune function, and disease-related pathways.

DISCUSSION

A significant correlation between heavy metals, cytokines, and oxidative stress markers reveals a potential role of vaping behavior in exposure to metals and changes in markers associated with DNA damage and inflammation. Our study demonstrates the importance of characterizing vaping behavior and puffing topography when examining the human health implications of ENDS use. https://doi.org/10.1289/EHP14321.

Long-term high fat diet aggravates the risk of lung fibrosis and lung cancer: transcriptomic analysis in the lung tissues of obese mice

Background

Previous studies reported significant relationships between obesity and pulmonary dysfunction. Here, we investigated genetic alterations in the lung tissues of high fat diet (HFD) induced obese mouse through transcriptomic and molecular analyses.

Methods

Eight-week-old male C57BL/6J mice were fed either a normal chow diet (NCD) or HFD for 12 weeks. We performed RNA sequencing, functional analysis of altered genes using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway data, Database for Annotation, Visualization and Integrated Discovery (DAVID) analysis, protein network analysis, quantitative real-time polymerase chain reaction, and Western blotting.

Results

We performed RNA sequencing analysis in the lung tissue of HFD mice. GO and KEGG pathway data presented higher expressions of genes related to lung fibrosis, and the changes of several pathways including regulation of nitrogen compound metabolic process, G protein-coupled receptor signaling, cancer pathway, and small cell lung cancer pathway. DAVID analysis and protein network analysis showed the changes of vascular endothelial growth factor, hypoxia-inducible factor-1 and rat sarcoma virus signaling related to vascular permeability, and protein network of MYC proto-oncogene gene related to cancer. In addition, we found increased protein and mRNA levels of the growth/differentiation factor 15 and alpha smooth muscle actin genes related to lung fibrosis in lung tissue of HFD mice.

Conclusions

HFD contributes to an increased risk of lung fibrosis and lung cancer. Thus, we propose that the genetic modulation and the molecular regulation of target pathways are essential to suppress pulmonary fibrosis in obese patients.

Analysis of nitrogen metabolism-related gene expression in hepatocellular carcinoma to establish relevant indicators for prediction of prognosis and guidance of immunotherapy

BACKGROUND

The prognosis of cancers is strongly connected with nitrogen metabolism (NM), which plays a critical role in the microenvironment and growth of tumors. It is unsubstantiated, however, how important NM-related genes are for the prognosis of hepatocellular carcinoma (HCC).

METHODS

Using publicly available data, we examined potential mechanisms of NM-related genes in HCC, created a predictive model, and assessed immune infiltration and medication sensitivity.

RESULTS

A prognostic model, which included 12 NM genes (COLQ, GNE, ISCU, MSRA, SARS2, SPHK1, CBS, GOT2, CHST1, EXTL2, GCLM, YARS1), was constructed based on regression analysis. The robustness of the model was validated using multiple methods. The high-risk (HR) and low-risk (LR) groups had varying degrees of immune infiltration, according to an immunology-related study. Of these, B cells and Type_II_IFN_Response were greatly infiltrated in the LR group, whereas aCDs, Macrophages, and Treg were heavily infiltrated in the HR group (p < 0.05). Because of higher immunophenoscore, the low-risk group could benefit from immunotherapy more. Drug sensitivity predictions indicated that people with high CBS expression and low GOT2 and ISCU expression may benefit more from treatment with SCH-772984, Pimasertib, Cobimetinib (isomer1), TAK-733, LY-3214996, ARRY-162, Cladribine, Fludarabine, and Hydroxyurea.

CONCLUSION

This work created a 12-gene signature based on NM, preliminary investigated immune infiltration in two risk categories, and discovered some possible anti-tumor medications. To sum up, our study findings offer fresh perspectives on the roles played by NM-associated genes in HCC development, prognosis, immunological response, and medication screening.

Exploring pH Dynamics in Amino Acid Solutions Under Low-Temperature Plasma Exposure

Low-temperature plasma (LTP) offers a promising alternative for cancer therapy, as it targets malignant cells selectively while minimizing damage to healthy tissues. Upon interaction with an aqueous solution, LTP generates reactive oxygen and nitrogen species and thereby influences the solution's pH, which is a crucial factor in cancer proliferation and response to treatment. This study investigated the effects of LTP on the pH of aqueous solutions, with a focus on the effect of LTP parameters such as voltage, frequency, and irradiation time. In addition, it explored the influence of solution composition, specifically the presence of the amino acids, glycine and serine, on pH changes; these amino acids are known to play significant roles in cancer proliferation. Our results indicated that LTP induces acidification in deionized water, in which the extent of acidification increased proportionally with plasma parameters. In glycine-containing solutions, pH changes were concentration-dependent, whereas serine-containing solutions maintained a constant pH across all tested concentrations. To investigate potential changes to the structural properties of glycine and serine exposed to LTP that could be responsible for different pH responses, we analyzed the samples using FTIR spectroscopy. A significant decrease in absorbance was observed for solutions with low concentrations of amino acids, suggesting their degradation.

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.

Biofluorescence imaging-guided spatial metabolic tracing: In vivo tracking of metabolic activity in circulating tumor cell-mediated multi-organ metastases

Circulating tumor cells (CTC) are considered metastatic precursors that are shed from the primary or metastatic deposits and navigate the bloodstream before undergoing extravasation to establish distant metastases. Metabolic reprogramming appears to be a hallmark of metastatic progression, yet current methods for evaluating metabolic heterogeneity within organ-specific metastases in vivo are limited. To overcome this challenge, we present Biofluorescence Imaging-Guided Spatial Metabolic Tracing (BIGSMT), a novel approach integrating in vivo biofluorescence imaging, stable isotope tracing, stain-free laser capture microdissection, and liquid chromatography-mass spectrometry. This innovative technology obviates the need for staining or intricate sample preparation, mitigating metabolite loss, and substantially enhances detection sensitivity and accuracy through chemical derivatization of polar metabolites in central carbon pathways. Application of BIGSMT to a preclinical CTC-mediated metastasis mouse model revealed significant heterogeneity in the in vivo carbon flux from glucose into glycolysis and the tricarboxylic acid (TCA) cycle across distinct metastatic sites. Our analysis indicates that carbon predominantly enters the TCA cycle through the enzymatic reaction catalyzed by pyruvate dehydrogenase. Thus, our spatially resolved BIGSMT technology provides fresh insights into the metabolic heterogeneity and evolution during melanoma CTC-mediated metastatic progression and points to novel therapeutic opportunities.

Current hotspots and trends in cancer metabolic reprogramming: a scientometric analysis

Background

Metabolic reprogramming (MR) in cancer (CA) has been a focus of intense research in the recent two decades. This phenomenon has attracted great interest because it offers potential targets for cancer therapy. To capture the intellectual landscape of this field, we conducted a bibliometric analysis to assess the scientific output, major contributors, and trends in the MR/CA research.

Methods

We performed a systematic search using the Web of Science to retrieve articles published on MR of cancer from 2006 until 2023. The bibliometric tools such as Biblioshiny, VOSviewer, and Microsoft Excel were used to identify the most prolific authors, institutions, citation patterns, and keywords. We also used co-citation analysis to map the conceptual structure of the field and identify influential publications. Furthermore, we examined the literature by analyzing publication years, citations, and research impact factors.

Results

A total of 4,465 publications about MR/CA were retrieved. Publications on MR/CA increased rapidly from 2006 to 2023. Frontiers in Oncology published the most papers, while Cell Metabolism had the most citations. Highly cited papers were mainly published in Cancer Cell, Nature, Cell, Science and Cell Metabolism. China and the United States led the way in publications and contributed the most to MR/CA research. The University of Texas System, Chinese Academy of Sciences, and Fudan University were the most productive institutions. The profitable authors were Deberardinis Ralph J and Chiarugi Paola. The current topics included MR in tumorigenesis and progression of CA, MR of tumor cells and tumor microenvironment, the effect of MR on the CA treatment, the underlying mechanisms of MR (such as gene regulation, epigenetics, extracellular vesicles, and gut microbiota), and the modulation of MR. Some topics such as tumor microenvironment, lipid MR, circular RNA, long noncoding RNA, exosome, prognostic model, and immunotherapy may be the focus of MR/CA research in the next few years.

Conclusion

This study evaluated the global scientific output in the field of MR/CA research, analyzing its quantitative characteristics. It identified some significant and distinguished papers and compiled information regarding the current status and evolving trends of MR/CA research.

Amino acid metabolic reprogramming in the tumor microenvironment and its implication for cancer therapy

Amino acids are essential building blocks for proteins, crucial energy sources for cell survival, and key signaling molecules supporting the resistant growth of tumor cells. In tumor cells, amino acid metabolic reprogramming is characterized by the enhanced uptake of amino acids as well as their aberrant synthesis, breakdown, and transport, leading to immune evasion and malignant progression of tumor cells. This article reviews the altered amino acid metabolism in tumor cells and its impact on tumor microenvironment, and also provides an overview of the current clinical applications of amino acid metabolism. Innovative drugs targeting amino acid metabolism hold great promise for precision and personalized cancer therapy.

Causal relationship between amino acids and ovarian cancer in the European population: A bidirectional Mendelian randomization study and meta-analysis

In recent years, an increasing number of observational studies have reported the impact of amino acids on ovarian cancer. However, Mendelian randomization studies have not yet been conducted to explore the causal relationship between them in the context of ovarian cancer. This study conducted Mendelian randomization (MR) analysis of 20 amino acids in relation to ovarian cancer data from 2 different sources within the European population, using a two-sample MR approach. The primary results from the inverse variance weighting analysis were then subjected to a meta-analysis, followed by multiple testing correction for the meta-analysis thresholds. Finally, reverse causality testing was performed on the positively associated amino acids and ovarian cancer. MR analyses were conducted for 20 amino acids with ovarian cancer data from both the Finngen R10 and Open genome-wide association study databases. The inverse variance weighted results from these 2 analyses were then combined through meta-analysis, with multiple corrections applied to the significance thresholds of the meta-analysis results. The findings showed that only cysteine had a significant association with ovarian cancer, with an (odds ratio) odds ratio value of 0.507 (95% confidence interval: 0.335-0.767, P = .025). The P-value of the combined MR and meta-analysis, after multiple testing correction, was 0.025, indicating statistical significance (P < .05). Additionally, cysteine did not show a reverse causal relationship with ovarian cancer in either data source. Cysteine is a protective factor for ovarian cancer, potentially reducing the risk of ovarian cancer and slowing the progression of the disease.

PRODH Regulates Tamoxifen Resistance through Ferroptosis in Breast Cancer Cells

BACKGROUND

Estrogen receptor-positive breast cancer accounts for around 70% of all cases. Tamoxifen, an anti-estrogenic inhibitor, is the primary drug used for this type of breast cancer treatment. However, tamoxifen resistance is a major challenge in clinics. Metabolic reprogramming, an emerging hallmark of cancer, plays a key role in cancer initiation, progression, and therapy resistance. The metabolism of non-essential amino acids such as serine, proline, and glutamine is involved in tumor metabolism reprogramming. Although the association of glutamine metabolism with tamoxifen resistance has been well established, the role of proline metabolism and its critical enzyme PRODH is unknown.

OBJECTIVE

The aim of this study is to explore the role and mechanism of PRODH in tamoxifen resistance in breast cancer cells.

METHODS

PRODH and GPX4 expressions in tamoxifen-resistant cells were detected using real-time PCR and Western blot analysis. The breast cells' response to tamoxifen was measured using MTT assays. Trans-well assays were used to detect cell migration and invasion. A Xenograft tumor assay was used to detect the role of PRODH in tumor growth. Reactive oxygen species were measured using flow cytometry.

RESULTS

PRODH expression is reduced in tamoxifen-resistant cells, and its overexpression enhances tamoxifen response in vitro and in vivo. Conversely, PRODH knockdown confers tamoxifen resistance in tamoxifen-sensitive cells. Mechanistic studies show that ferroptosis is inhibited in tamoxifen-resistant cells and overexpression of PRODH restores the ferroptosis in tamoxifen-resistant cells. Moreover, Ferrostatin-1 (Fer-1), the ferroptosis inhibitor, reversed the effect of PRODH on tamoxifen resistance.

CONCLUSIONS

These findings suggest that PRODH regulates tamoxifen resistance by regulating ferroptosis in tamoxifen-resistant cells.

Asparagine Dependency Is a Targetable Metabolic Vulnerability in TP53-Altered Castration-Resistant Prostate Cancer

TP53 tumor suppressor is frequently altered in lethal, castration-resistant prostate cancer (CRPC). However, to date there are no effective treatments that specifically target TP53 alterations. Using transcriptomic and metabolomic analyses, we have shown here that TP53-altered prostate cancer exhibits an increased dependency on asparagine (Asn) and overexpresses Asn synthetase (ASNS), the enzyme catalyzing the synthesis of Asn. Mechanistically, the loss or mutation of TP53 transcriptionally activated ASNS expression, directly and via mTORC1-mediated ATF4 induction, driving de novo Asn biosynthesis to support CRPC growth. TP53-altered CRPC cells were sensitive to Asn restriction by knockdown of ASNS or L-asparaginase treatment to deplete the intracellular and extracellular sources of Asn, respectively, and cell viability was rescued by Asn addition. Notably, pharmacological inhibition of intracellular Asn biosynthesis using a glutaminase inhibitor and depletion of extracellular Asn with L-asparaginase significantly reduced Asn production and effectively impaired CRPC growth. This study highlights the significance of ASNS-mediated metabolic adaptation as a synthetic vulnerability in CRPC with TP53 alterations, providing a rationale for targeting Asn production to treat these lethal prostate cancers. Significance: TP53-mutated castration-resistant prostate cancer is dependent on asparagine biosynthesis due to upregulation of ASNS and can be therapeutically targeted by approaches that deplete intracellular and extracellular asparagine.

Integrated machine learning screened glutamine metabolism-associated biomarker SLC1A5 to predict immunotherapy response in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) stands as one of the most prevalent malignancies. While PD-1 immune checkpoint inhibitors have demonstrated promising therapeutic efficacy in HCC, not all patients exhibit a favorable response to these treatments. Glutamine is a crucial immune cell regulatory factor, and tumor cells exhibit glutamine dependence. In this study, HCC patients were divided into two subtypes (C1 and C2) based on glutamine metabolism-related genes via consensus clustering. The C1 pattern, in contrast to C2, was associated with a lower survival probability among HCC patients. Additionally, the C1 pattern exhibited higher proportions of patients with advanced tumor stages. The activity of C1 in glutamine metabolism and transport is significantly enhanced, while its oxidative phosphorylation activity is reduced. And, C1 was mainly involved in the progression-related pathway of HCC. Furthermore, C1 exhibited high levels of immunosuppressive cells, cytokine-receptor interactions and immune checkpoint genes, suggesting C1 as an immunosuppressive subtype. After stepwise selection based on integrated four machine learning methods, SLC1A5 was finally identified as the pivotal gene that distinguishes the subtypes. The expression of SLC1A5 was significantly positively correlated with immunosuppressive status. SLC1A5 showed the most significant correlation with macrophage infiltration, and this correlation was confirmed through the RNA-seq data of CLCA project and our cohort. Low-SLC1A5-expression samples had better immunogenicity and responsiveness to immunotherapy. As expected, SubMap and survival analysis indicated that individuals with low SLC1A5 expression were more responsive to anti-PD1 therapy. Collectively, this study categorized HCC patients based on glutamine metabolism-related genes and proposed two subclasses with different clinical traits, biological behavior, and immune status. Machine learning was utilized to identify the hub gene SLC1A5 for HCC classification, which also could predict immunotherapy response.

Factors Determining Epithelial-Mesenchymal Transition in Cancer Progression

Epithelial-mesenchymal transition (EMT) is a process in which an epithelial cell undergoes multiple modifications, acquiring both morphological and functional characteristics of a mesenchymal cell. This dynamic process is initiated by various inducing signals that activate numerous signaling pathways, leading to the stimulation of transcription factors. EMT plays a significant role in cancer progression, such as metastasis and tumor heterogeneity, as well as in drug resistance. In this article, we studied molecular mechanisms, epigenetic regulation, and cellular plasticity of EMT, as well as microenvironmental factors influencing this process. We included both in vivo and in vitro models in EMT investigation and clinical implications of EMT, such as the use of EMT in curing oncological patients and targeting its use in therapies. Additionally, this review concludes with future directions and challenges in the wide field of EMT.

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.

The role of metabolic reprogramming in immune escape of triple-negative breast cancer

Triple-negative breast cancer (TNBC) has become a thorny problem in the treatment of breast cancer because of its high invasiveness, metastasis and recurrence. Although immunotherapy has made important progress in TNBC, immune escape caused by many factors, especially metabolic reprogramming, is still the bottleneck of TNBC immunotherapy. Regrettably, the mechanisms responsible for immune escape remain poorly understood. Exploring the mechanism of TNBC immune escape at the metabolic level provides a target and direction for follow-up targeting or immunotherapy. In this review, we focus on the mechanism that TNBC affects immune cells and interstitial cells through hypoxia, glucose metabolism, lipid metabolism and amino acid metabolism, and changes tumor metabolism and tumor microenvironment. This will help to find new targets and strategies for TNBC immunotherapy.

The unique catalytic properties of PSAT1 mediate metabolic adaptation to glutamine blockade

Cultured cancer cells frequently rely on the consumption of glutamine and its subsequent hydrolysis by glutaminase (GLS). However, this metabolic addiction can be lost in the tumour microenvironment, rendering GLS inhibitors ineffective in the clinic. Here we show that glutamine-addicted breast cancer cells adapt to chronic glutamine starvation, or GLS inhibition, via AMPK-mediated upregulation of the serine synthesis pathway (SSP). In this context, the key product of the SSP is not serine, but α-ketoglutarate (α-KG). Mechanistically, we find that phosphoserine aminotransferase 1 (PSAT1) has a unique capacity for sustained α-KG production when glutamate is depleted. Breast cancer cells with resistance to glutamine starvation or GLS inhibition are highly dependent on SSP-supplied α-KG. Accordingly, inhibition of the SSP prevents adaptation to glutamine blockade, resulting in a potent drug synergism that suppresses breast tumour growth. These findings highlight how metabolic redundancy can be context dependent, with the catalytic properties of different metabolic enzymes that act on the same substrate determining which pathways can support tumour growth in a particular nutrient environment. This, in turn, has practical consequences for therapies targeting cancer metabolism.

A panel of four plasma amino acids is a promising biomarker for newly diagnosed bladder cancer

BACKGROUND

Metastasis and recurrence are the main causes of death in post-operative bladder cancer (BC), emphasizing the importance of exploring early-stage diagnostic markers. Serum biomarkers constitute a promising diagnostic approach for asymptomatic stage cancer as they are non-invasive, have high accuracy and low cost.

AIMS

To correlate concentrations of plasma amino acids with BC progression to assess their utility as an early-stage diagnostic.

METHODS

Newly diagnosed BC patients (n = 95) and normal controls (n = 96) were recruited during the period from 1 December 2018 to 30 December 2020. General and food frequency questionnaires established their basic information and dietary intake data. Venous blood samples were collected from fasting subjects and used to detect levels of plasma amino acids by liquid chromatography-mass spectrometry. Verification was performed on the GSE13507 transcriptome gene expression matrix of BC from Gene Expression Omnibus (GEO) database.

RESULTS

Eleven amino acids have been identified as altered in the plasma of newly diagnosed BC patients compared to controls (P < 0.05). Adjusted by gender, education, smoking and other factors, plasma ornithine level (OR = 0.256, 95% CI: 0.104-0.630) is a protective factor for BC, plasma levels of methionine (OR = 3.460, 95% CI: 1.384-8.651), arginine (OR = 3.851, 95% CI: 1.542-9.616), and glutamate (OR = 3.813, 95% CI: 1.543-9.419) are all risk factors for BC. ROC analysis demonstrated that the combination of plasma ornithine, methionine, arginine and glutamate could accurately diagnose BC (AUC = 0.84, 95% CI: 0.747-0.833). In addition, the mRNA level of arginase 1 was decreased (P < 0.05), while the inducible nitric oxide synthase was increased significantly, which may be linked with the disturbance of arginine metabolism in BC patients. Further analysis of GEO database confirmed the role of arginine metabolism.

CONCLUSION

A biomarker panel containing four amino acids may provide a feasible strategy for the early diagnosis of BC. However, further validation is required through prospective studies.

Screening of postoperative adjuvant chemotherapy-related serum metabolic markers in breast cancer patients based on 1H NMR metabonomics

Background

Breast cancer (BC) has the highest incidence rate among female malignant tumors. Adjuvant chemotherapy is commonly used to reduce micrometastasis in postoperative patients. However, monitoring the efficacy of chemotherapy in BC is a major challenge in clinical practice. In this study, 1H nuclear magnetic resonance (NMR) metabonomics was performed to explore the serum metabolic characteristics of BC patients before and after adjuvant chemotherapy.

Methods

In this study, we collected serum samples from 51 healthy controls and 61 BC patients before and after chemotherapy for 1H NMR metabolomic analysis, and tested the performance of each metabolite and combination segment by the receiver operating characteristic (ROC) curves.

Results

Nine metabolites, namely glutamine, citrate, creatine, glycerophosphatidylcholine/phosphatidylcholine, glycine, 1-methylhistidine, lactate, pyruvate and formate had significant changes in BC patients before chemotherapy compared with healthy controls. Lactate, pyruvate, 1-methylhistidine and formate were found to be inversely regulated by chemotherapy. ROC analysis showed that a combination of the four metabolites had good prediction for chemotherapy efficacy with area under the curve of 0.958, sensitivity of 98.36% and specificity of 91.30%. There was no significant correlation between chemotherapy-related metabolites and clinical indicators of cancer patients, indicating that they can be used to evaluate the chemotherapy efficacy of patients with different clinical indicators.

Conclusions

Effectively, dynamic and non-invasive metabolic markers for the evaluation of the efficacy of chemotherapy were identified in this study.

The Role of Salivary Vascular Endothelial Growth Factor A, Cytokines, and Amino Acids in Immunomodulation and Angiogenesis in Breast Cancer

In this work, we focused on the analysis of VEGF content in saliva and its relationship with pro-inflammatory cytokines and amino acids involved in immunomodulation and angiogenesis in breast cancer. The study included 230 breast cancer patients, 92 patients with benign breast disease, and 59 healthy controls. Before treatment, saliva samples were obtained from all participants, and the content of VEGF and cytokines in saliva was determined by an enzyme-linked immunosorbent assay, as well as the content of amino acids by high-performance liquid chromatography. It was found that VEGF was positively correlated with the level of pro-inflammatory cytokines IL-1β (r = 0.6367), IL-6 (r = 0.3813), IL-8 (r = 0.4370), and IL-18 (r = 0.4184). Weak correlations were shown for MCP-1 (r = 0.2663) and TNF-α (r = 0.2817). For the first time, we demonstrated changes in the concentration of VEGF and related cytokines in saliva in different molecular biological subtypes of breast cancer depending on the stage of the disease, differentiation, proliferation, and metastasis to the lymph nodes. A correlation was established between the expression of VEGF and the content of aspartic acid (r = -0.3050), citrulline (r = -0.2914), and tryptophan (r = 0.3382) in saliva. It has been suggested that aspartic acid and citrulline influence the expression of VEGF via the synthesis of the signaling molecule NO, and then tryptophan ensures tolerance of the immune system to tumor cells.

Elevated SLC1A5 associated with poor prognosis and therapeutic resistance to transarterial chemoembolization in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is a common malignant tumor, and glutamine is vital for tumor cells. The role of glutamine transporter SLC1A5 in tumor progression and transarterial chemoembolization (TACE) efficacy is under study. This research seeks to determine the impact of SLC1A5 expression on the prognosis and TACE efficacy of HCC and elucidate its mechanisms.

METHODS

SLC1A5 expression in HCC, correlation with patient outcomes, and response to TACE were studied in an open access liver cancer dataset and confirmed in our cohort. Additionally, the correlation between SLC1A5 expression and hypoxia, angiogenesis and immune infiltration was analyzed and verified by immunohistochemistry, immunofluorescence and transcriptome sequencing. Liver cancer cell lines with SLC1A5 expression knockdown or overexpression were constructed, and cell proliferation, colony formation, apoptosis, migration and drug sensitivity as well as in vivo xenograft tumor were measured. A gene set enrichment analysis was conducted to determine the signaling pathway influenced by SLC1A5, and a western blot analysis was performed to detect protein expression alterations.

RESULTS

SLC1A5 expression was higher in HCC tissue and associated with poor survival and TACE resistance. Hypoxia could stimulate the upregulation of glutamine transport, angiogenesis and SLC1A5 expression. The SLC1A5 expression was positively correlated with hypoxia and angiogenesis-related genes, immune checkpoint pathways, macrophage, Tregs, and other immunosuppressive cells infiltration. Knockdown of SLC1A5 decreased proliferation, colony formation, and migration, but increased apoptosis and increased sensitivity to chemotherapy drugs. Downregulation of SLC1A5 resulted in a decrease in Vimentin and N-cadherin expression, yet an increase in E-cadherin expression. Upregulation of SLC1A5 increased Vimentin and N-cadherin expression, while decreasing E-cadherin. Overexpression of β-catenin in SLC1A5-knockdown HCC cell lines could augment Vimentin and N-cadherin expression, suppress E-cadherin expression, and increase the migration and drug resistance.

CONCLUSIONS

Elevated SLC1A5 was linked to TACE resistance and survival shortening in HCC patients. SLC1A5 was positively correlated with hypoxia, angiogenesis, and immunosuppression. SLC1A5 may mediate HCC cell migration and drug resistance via Epithelial-mesenchymal transition (EMT) pathway.

Beyond the Bile: Exploring the Microbiome and Metabolites in Cholangiocarcinoma

INTRODUCTION

Cholangiocarcinoma (CCC) still has a high mortality rate despite improvements in diagnostic and therapeutic techniques. The role of the human microbiome in CCC is poorly understood, and a recent metagenomic analysis demonstrated a significant correlation between microbiome-associated carcinogenesis and CCC. This study aimed to investigate changes in microbiome composition associated with CCC and its metabolic signature by integrating taxonomic and functional information with metabolomics data and in vitro experimental results.

METHODS

From February 2019 to January 2021, this study included patients who underwent endoscopic retrograde cholangiopancreatography (ERCP), both with and without a diagnosis of CCC. Bile samples were collected via endoscopic nasobiliary drainages (ENBD) and subjected to DNA extraction, PCR amplification of the bacterial 16S rRNA gene V3-V4 region, and data analysis using QIIME2. In vitro Carboxyfluorescein succinimidyl ester (CFSE) proliferation and Annexin V/PI apoptosis assays were performed to investigate the effects of metabolites on CCC cells.

RESULTS

A total of 24 patients were included in the study. Bile fluid analysis revealed a significantly higher abundance of Escherichia coli in the CCC group. Alpha diversity analyses exhibited significant differences between the CCC and non-CCC groups, and Nuclear Magnetic Resonance (NMR) spectroscopy metabolic profiling identified 15 metabolites with significant concentration differences; isoleucine showed the most notable difference. In vitro experiments demonstrated that isoleucine suppressed CCC cell proliferation but did not induce apoptosis.

CONCLUSIONS

This research underlines the significance of biliary dysbiosis and specific bile metabolites, such as isoleucine, in influencing the development and progression of CCC.

Arginine deprivation enriches lung cancer proteomes with cysteine by inducing arginine-to-cysteine substitutants

Many types of human cancers suppress the expression of argininosuccinate synthase 1 (ASS1), a rate-limiting enzyme for arginine production. Although dependency on exogenous arginine can be harnessed by arginine-deprivation therapies, the impact of ASS1 suppression on the quality of the tumor proteome is unknown. We therefore interrogated proteomes of cancer patients for arginine codon reassignments (substitutants) and surprisingly identified a strong enrichment for cysteine (R>C) in lung tumors specifically. Most R>C events did not coincide with genetically encoded R>C mutations but were likely products of tRNA misalignments. The expression of R>C substitutants was highly associated with oncogenic kelch-like epichlorohydrin (ECH)-associated protein 1 (KEAP1)-pathway mutations and suppressed by intact-KEAP1 in KEAP1-mutated cancer cells. Finally, functional interrogation indicated a key role for R>C substitutants in cell survival to cisplatin, suggesting that regulatory codon reassignments endow cancer cells with more resilience to stress. Thus, we present a mechanism for enriching lung cancer proteomes with cysteines that may affect therapeutic decisions.

Stress-Induced Proteasome Sub-Cellular Translocation in Cardiomyocytes Causes Altered Intracellular Calcium Handling and Arrhythmias

The ubiquitin-proteasome system (UPS) is an essential mechanism responsible for the selective degradation of substrate proteins via their conjugation with ubiquitin. Since cardiomyocytes have very limited self-renewal capacity, as they are prone to protein damage due to constant mechanical and metabolic stress, the UPS has a key role in cardiac physiology and pathophysiology. While altered proteasomal activity contributes to a variety of cardiac pathologies, such as heart failure and ischemia/reperfusion injury (IRI), the environmental cues affecting its activity are still unknown, and they are the focus of this work. Following a recent study by Ciechanover's group showing that amino acid (AA) starvation in cultured cancer cell lines modulates proteasome intracellular localization and activity, we tested two hypotheses in human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs, CMs): (i) AA starvation causes proteasome translocation in CMs, similarly to the observation in cultured cancer cell lines; (ii) manipulation of subcellular proteasomal compartmentalization is associated with electrophysiological abnormalities in the form of arrhythmias, mediated via altered intracellular Ca2+ handling. The major findings are: (i) starving CMs to AAs results in proteasome translocation from the nucleus to the cytoplasm, while supplementation with the aromatic amino acids tyrosine (Y), tryptophan (W) and phenylalanine (F) (YWF) inhibits the proteasome recruitment; (ii) AA-deficient treatments cause arrhythmias; (iii) the arrhythmias observed upon nuclear proteasome sequestration(-AA+YWF) are blocked by KB-R7943, an inhibitor of the reverse mode of the sodium-calcium exchanger NCX; (iv) the retrograde perfusion of isolated rat hearts with AA starvation media is associated with arrhythmias. Collectively, our novel findings describe a newly identified mechanism linking the UPS to arrhythmia generation in CMs and whole hearts.

Salivary Tryptophan as a Metabolic Marker of HER2-Negative Molecular Subtypes of Breast Cancer

Changes in the concentration of tryptophan (Trp) indicate a serious metabolic restructuring, which is both a cause and a consequence of many diseases. This work examines the upward change in salivary Trp concentrations among patients with breast cancer. This study involved volunteers divided into three groups: breast cancer (n = 104), non-malignant breast pathologies (n = 30) and healthy controls (n = 20). In all participants, before treatment, the quantitative content of Trp in saliva was determined by capillary electrophoresis. In 20 patients with breast cancer, Trp was re-tested four weeks after surgical removal of the tumor. An increase in the Trp content in saliva in breast cancer has been shown, which statistically significantly decreases after surgical removal of the tumor. A direct correlation was found between increased Trp levels with the degree of malignancy and aggressive molecular subtypes of breast cancer, namely triple negative and luminal B-like HER2-negative. These conclusions were based on an increase in Ki-67 and an increase in Trp in HER2-negative and progesterone-negative subtypes. Factors under which an increase in Trp concentration in saliva was observed were identified: advanced stage of breast cancer, the presence of regional metastasis, low tumor differentiation, a lack of expression of HER2, estrogen and progesterone receptors and the high proliferative activity of the tumor. Thus, the determination of salivary Trp may be a valuable tool in the study of metabolic changes associated with cancer, particularly breast cancer.

Homology modeling and molecular docking studies to decrease glutamine affinity of Yarrowia lipolytica L-asparaginase

L-Asparaginase is a key component in the treatment of leukemias and lymphomas. However, the glutamine affinity of this therapeutic enzyme is an off-target activity that causes several side effects. The modeling and molecular docking study of Yarrowia lipolytica L-asparaginase (YL-ASNase) to reduce its l-glutamine affinity and increase its stability was the aim of this study. Protein-ligand interactions of wild-type and different mutants of YL-ASNase against L-asparagine compared to l-glutamine were assessed using AutoDock Vina tools because the crystal structure of YL-ASNase does not exist in the protein data banks. The results showed that three mutants, T171S, T171S-N60A, and T171A-T223A, caused a considerable increase in L-asparagine affinity and a decrease in l-glutamine affinity as compared to the wild-type and other mutants. Then, molecular dynamics simulation and MM/GBSA free energy were applied to assess the stability of protein structure and its interaction with ligands. The three mutated proteins, especially T171S-N60A, had higher stability and interactions with L-asparagine than l-glutamine in comparison with the wild-type. The YL-ASNase mutants could be introduced as appropriate therapeutic candidates that might cause lower side effects. However, the functional properties of these mutated enzymes need to be confirmed by genetic manipulation and in vitro and in vivo studies.

Evodiamine inhibits EPRS expression to regulate glutamate metabolism and proliferation of oral squamous cell carcinoma cells

The effects of evodiamine (EVO) on oral squamous cell carcinoma (OSCC) are not yet understood. Based on our earlier findings, we hypothesized that evodiamine may affect OSCC cell proliferation and glutamate metabolism by modulating the expression of EPRS (glutamyl-prolyl-tRNA synthetase 1). From GEPIA, we obtained EPRS expression data in patients with OSCC as well as survival prognosis data. An animal model using Cal27 cells in BALB/c nude mice was established. The expression of EPRS was assessed by immunofluorescence, Western blotting, and quantitative PCR. Glutamate measurements were performed to evaluate the impact of evodiamine on glutamate metabolism of Cal27 and SAS tumor cells. transient transfection techniques were used to knock down and modulate EPRS in these cells. EPRS is expressed at higher levels in OSCC than in normal tissues, and it predicts poor prognosis in patients. In a nude mouse xenograft model, evodiamine inhibited tumor growth and the expression of EPRS. Evodiamine impacted cell proliferation, glutamine metabolism, and EPRS expression on Cal27 and SAS cell lines. In EPRS knockdown cell lines, both cell proliferation and glutamine metabolism are suppressed. EPRS's overexpression partially restores evodiamine's inhibitory effects on cell proliferation and glutamine metabolism. This study provides crucial experimental evidence supporting the potential therapeutic application of evodiamine in treating OSCC. Evodiamine exhibits promising anti-tumor effects by targeting EPRS to regulate glutamate metabolism.

Amino acid deprivation induces TXNIP expression by NRF2 downregulation

Thioredoxin-interacting protein (TXNIP) is sensitive to oxidative stress and is involved in the pathogenesis of various metabolic, cardiovascular, and neurodegenerative disorders. Therefore, several studies have suggested that TXNIP is a promising therapeutic target for several diseases, particularly cancer and diabetes. However, the regulation of TXNIP expression under amino acid (AA)-restricted conditions is not well understood. In the present study, we demonstrated that TXNIP expression was promoted by the deprivation of AAs, especially arginine, glutamine, lysine, and methionine, in non-small cell lung cancer (NSCLC) cells. Interestingly, we determined that increased TXNIP expression induced by AA deprivation was associated with nuclear factor erythroid 2-related factor 2 (NRF2) downregulation, but not with activating transcription factor 4 (ATF4) activation. Furthermore, N-acetyl-l-cysteine (NAC), a scavenger of reactive oxygen species (ROS), suppressed TXNIP expression in NSCLC cells deprived of AA. Collectively, the induction of TXNIP expression by AA deprivation was mediated by ROS production, potentially through NRF2 downregulation. Our findings suggest that TXNIP expression may be associated with the redox homeostasis of AA metabolism and provide a possible rationale for a therapeutic strategy to treat cancer with AA restriction.

Metabolism-regulated ferroptosis in cancer progression and therapy

Cancer metabolism mainly includes carbohydrate, amino acid and lipid metabolism, each of which can be reprogrammed. These processes interact with each other to adapt to the complicated microenvironment. Ferroptosis is a regulated cell death induced by iron-dependent lipid peroxidation, which is morphologically different from apoptosis, necrosis, necroptosis, pyroptosis, autophagy-dependent cell death and cuprotosis. Cancer metabolism plays opposite roles in ferroptosis. On the one hand, carbohydrate metabolism can produce NADPH to maintain GPX4 and FSP1 function, and amino acid metabolism can provide substrates for synthesizing GPX4; on the other hand, lipid metabolism might synthesize PUFAs to trigger ferroptosis. The mechanisms through which cancer metabolism affects ferroptosis have been investigated extensively for a long time; however, some mechanisms have not yet been elucidated. In this review, we summarize the interaction between cancer metabolism and ferroptosis. Importantly, we were most concerned with how these targets can be utilized in cancer therapy.

Filament formation drives catalysis by glutaminase enzymes important in cancer progression

The glutaminase enzymes GAC and GLS2 catalyze the hydrolysis of glutamine to glutamate, satisfying the 'glutamine addiction' of cancer cells. They are the targets of anti-cancer drugs; however, their mechanisms of activation and catalytic activity have been unclear. Here we demonstrate that the ability of GAC and GLS2 to form filaments is directly coupled to their catalytic activity and present their cryo-EM structures which provide a view of the conformational states essential for catalysis. Filament formation guides an 'activation loop' to assume a specific conformation that works together with a 'lid' to close over the active site and position glutamine for nucleophilic attack by an essential serine. Our findings highlight how ankyrin repeats on GLS2 regulate enzymatic activity, while allosteric activators stabilize, and clinically relevant inhibitors block, filament formation that enables glutaminases to catalyze glutaminolysis and support cancer progression.

The recombinant L-lysine α-oxidase from the fungus Trichoderma harzianum promotes apoptosis and necrosis of leukemia CD34 + hematopoietic cells

BACKGROUND

In hematologic cancers, including leukemia, cells depend on amino acids for rapid growth. Anti-metabolites that prevent their synthesis or promote their degradation are considered potential cancer treatment agents. Amino acid deprivation triggers proliferation inhibition, autophagy, and programmed cell death. L-lysine, an essential amino acid, is required for tumor growth and has been investigated for its potential as a target for cancer treatment. L-lysine α-oxidase, a flavoenzyme that degrades L-lysine, has been studied for its ability to induce apoptosis and prevent cancer cell proliferation. In this study, we describe the use of L-lysine α-oxidase (LO) from the filamentous fungus Trichoderma harzianum for cancer treatment.

RESULTS

The study identified and characterized a novel LO from T. harzianum and demonstrated that the recombinant protein (rLO) has potent and selective cytotoxic effects on leukemic cells by triggering the apoptotic cascade through mitochondrial dysfunction.

CONCLUSIONS

The results support future translational studies using the recombinant LO as a potential drug for the treatment of leukemia.

Loss of RACK1 promotes glutamine addiction via activating AKT/mTOR/ASCT2 axis to facilitate tumor growth in gastric cancer

BACKGROUND

Metabolic reprogramming is closely related to the development of gastric cancer (GC), which remains as the fourth leading cause of cancer-related death worldwide. As a tumor suppressor for GC, whether receptor for activated C-kinase 1 (RACK1) play a modulatory role in metabolic reprogramming remains largely unclear.

METHODS

GC cell lines and cell-derived xenograft mouse model were used to identify the biological function of RACK1. Flow cytometry and Seahorse assays were applied to examine cell cycle and oxygen consumption rate (OCR), respectively. Western blot, real-time PCR and autophagy double fluorescent assays were utilized to explore the signaling. Immunohistochemistry was performed to detect the expression of RACK1 and other indicators in tissue sections.

RESULTS

Loss of RACK1 facilitated the viability, colony formation, cell cycle progression and OCR of GC cells in a glutamine-dependent manner. Further investigation revealed that RACK1 knockdown inhibited the lysosomal degradation of Alanine-serine-cysteine amino acid transporter 2 (ASCT2). Mechanistically, depletion of RACK1 remarkably decreased PTEN expression through up-regulating miR-146b-5p, leading to the activation of AKT/mTOR signaling pathway which dampened autophagy flux subsequently. Moreover, knockdown of ASCT2 could reverse the promotive effect of RACK1 depletion on GC tumor growth both in vitro and in vivo. Tissue microarray confirmed that RACK1 was negatively correlated with the expression of ASCT2 and p62, as well as the phosphorylation of mTOR.

CONCLUSION

Together, our results demonstrate that the suppressive function of RACK1 in GC is associated with ASCT2-mediated glutamine metabolism, and imply that targeting RACK1/ASCT2 axis provides potential strategies for GC treatment.

Amino acid metabolism in tumor biology and therapy

Amino acid metabolism plays important roles in tumor biology and tumor therapy. Accumulating evidence has shown that amino acids contribute to tumorigenesis and tumor immunity by acting as nutrients, signaling molecules, and could also regulate gene transcription and epigenetic modification. Therefore, targeting amino acid metabolism will provide new ideas for tumor treatment and become an important therapeutic approach after surgery, radiotherapy, and chemotherapy. In this review, we systematically summarize the recent progress of amino acid metabolism in malignancy and their interaction with signal pathways as well as their effect on tumor microenvironment and epigenetic modification. Collectively, we also highlight the potential therapeutic application and future expectation.

Directed evolution of biomass intensive CHO cells by adaptation to sub-physiological temperature

We report a simple and effective means to increase the biosynthetic capacity of host CHO cells. Lonza proprietary CHOK1SV® cells were evolved by serial sub-culture for over 150 generations at 32 °C. During this period the specific proliferation rate of hypothermic cells gradually recovered to become comparable to that of cells routinely maintained at 37 °C. Cold-adapted cell populations exhibited (1) a significantly increased volume and biomass content (exemplified by total RNA and protein), (2) increased mitochondrial function, (3) an increased antioxidant capacity, (4) altered central metabolism, (5) increased transient and stable productivity of a model IgG4 monoclonal antibody and Fc-fusion protein, and (6) unaffected recombinant protein N-glycan processing. This phenotypic transformation was associated with significant genome-scale changes in both karyotype and the relative abundance of thousands of cellular mRNAs across numerous functional groups. Taken together, these observations provide evidence of coordinated cellular adaptations to sub-physiological temperature. These data reveal the extreme genomic/functional plasticity of CHO cells, and that directed evolution is a viable genome-scale cell engineering strategy that can be exploited to create host cells with an increased cellular capacity for recombinant protein production.

The Role of Amino Acids in Non-Enzymatic Antioxidant Mechanisms in Cancer: A Review

Currently, the antioxidant properties of amino acids and their role in the physicochemical processes accompanying oxidative stress in cancer remain unclear. Cancer cells are known to extensively uptake amino acids, which are used as an energy source, antioxidant precursors that reduce oxidative stress in cancer, and as regulators of inhibiting or inducing tumor cell-associated gene expression. This review examines nine amino acids (Cys, His, Phe, Met, Trp, Tyr, Pro, Arg, Lys), which play a key role in the non-enzymatic oxidative process in various cancers. Conventionally, these amino acids can be divided into two groups, in one of which the activity increases (Cys, Phe, Met, Pro, Arg, Lys) in cancer, and in the other, it decreases (His, Trp, Tyr). The review examines changes in the metabolism of nine amino acids in eleven types of oncology. We have identified the main nonspecific mechanisms of changes in the metabolic activity of amino acids, and described direct and indirect effects on the redox homeostasis of cells. In the future, this will help to understand better the nature of life of a cancer cell and identify therapeutic targets more effectively.

The Role of Tumor Metabolic Reprogramming in Tumor Immunity

The occurrence and development of tumors require the metabolic reprogramming of cancer cells, namely the alteration of flux in an autonomous manner via various metabolic pathways to meet increased bioenergetic and biosynthetic demands. Tumor cells consume large quantities of nutrients and produce related metabolites via their metabolism; this leads to the remodeling of the tumor microenvironment (TME) to better support tumor growth. During TME remodeling, the immune cell metabolism and antitumor immune activity are affected. This further leads to the escape of tumor cells from immune surveillance and therefore to abnormal proliferation. This review summarizes the regulatory functions associated with the abnormal biosynthesis and activity of metabolic signaling molecules during the process of tumor metabolic reprogramming. In addition, we provide a comprehensive description of the competition between immune cells and tumor cells for nutrients in the TME, as well as the metabolites required for tumor metabolism, the metabolic signaling pathways involved, and the functionality of the immune cells. Finally, we summarize current research targeted at the development of tumor immunotherapy. We aim to provide new concepts for future investigations of the mechanisms underlying the metabolic reprogramming of tumors and explore the association of these mechanisms with tumor immunity.

Exploring the interplay between metabolomics and genetics in Parkinson's disease: Insights from ongoing research and future avenues

Parkinson's disease (PD) is a widespread neurodegenerative disorder, whose complex aetiology remains under construction. While rare variants have been associated with the monogenic PD form, most PD cases are influenced by multiple genetic and environmental aspects. Nonetheless, the pathophysiological pathways and molecular networks involved in monogenic/idiopathic PD overlap, and genetic variants are decisive in elucidating the convergent underlying mechanisms of PD. In this scenario, metabolomics has furnished a dynamic and systematic picture of the synergy between the genetic background and environmental influences that impact PD, making it a valuable tool for investigating PD-related metabolic dysfunctions. In this review, we performed a brief overview of metabolomics current research in PD, focusing on significant metabolic alterations observed in idiopathic PD from different biofluids and strata and exploring how they relate to genetic factors associated with monogenic PD. Dysregulated amino acid metabolism, lipid metabolism, and oxidative stress are the critical metabolic pathways implicated in both genetic and idiopathic PD. By merging metabolomics and genetics data, it is possible to distinguish metabolic signatures of specific genetic backgrounds and to pinpoint subgroups of PD patients who could derive personalized therapeutic benefits. This approach holds great promise for advancing PD research and developing innovative, cost-effective treatments.

Oxidative stress regulation and related metabolic pathways in epithelial-mesenchymal transition of breast cancer stem cells

Epithelial-mesenchymal transition (EMT) is a cell remodeling process in which epithelial cells undergo a reversible phenotype switch via the loss of adhesion capacity and acquisition of mesenchymal characteristics. In other words, EMT activation can increase invasiveness and metastatic properties, and prevent the sensitivity of tumor cells to chemotherapeutics, as mesenchymal cells have a higher resistance to chemotherapy and immunotherapy. EMT is orchestrated by a complex and multifactorial network, often linked to episodic, transient, or partial events. A variety of factors have been implicated in EMT development. Based on this concept, multiple metabolic pathways and master transcription factors, such as Snail, Twist, and ZEB, can drive the EMT. Emerging evidence suggests that oxidative stress plays a significant role in EMT induction. One emerging theory is that reducing mitochondrial-derived reactive oxygen species production may contribute to EMT development. This review describes how metabolic pathways and transcription factors are linked to EMT induction and addresses the involvement of signaling pathways.

Shuttle between arginine and lysine: influence on cancer immunonutrition

Amino acids which are essential nutrients for all cell types' survival are also recognised to serve as opportunistic/alternative fuels in cancers auxotrophic for specific amino acids. Accordingly, restriction of amino acids has been utilised as a therapeutic strategy in these cancers. Contrastingly, amino acid deficiencies in cancer are found to greatly impair immune functions, increasing mortality and morbidity rates. Dietary and supplemental amino acids in such conditions have revealed their importance as 'immunonutrients' by modulating cellular homeostasis processes and halting malignant progression. L-arginine specifically has attracted interest as an immunonutrient by acting as a nodal regulator of immune responses linked to carcinogenesis processes through its versatile signalling molecule, nitric oxide (NO). The quantum of NO generated directly influences the cytotoxic and cytostatic processes of cell cycle arrest, apoptosis, and senescence. However, L-lysine, a CAT transporter competitor for arginine effectively limits arginine input at high L-lysine concentrations by limiting arginine-mediated effects. The phenomenon of arginine-lysine antagonism can, therefore, be hypothesised to influence the immunonutritional effects exerted by arginine. The review highlights aspects of lysine's interference with arginine-mediated NO generation and its consequences on immunonutritional and anti-cancer effects, and discusses possible alternatives to manage the condition. However, further research that considers monitoring lysine levels in arginine immunonutritional therapy is essential to conclude the hypothesis.

High WFDC3 gene expression is associated with poor prognosis and reduced immune cells infiltration in pancreatic adenocarcinoma: A study using the TCGA database and bioinformatics analysis

Whey-acidic-protein (WAP) four-disulfide core domain protein 3 (WFDC3) is one of the WAP family proteins. This protein family is associated with the development of solid tumors and affects the tumor immunological microenvironment. However, the prognostic value of WFDC3 in pancreatic adenocarcinoma (PAAD) and its effect on the tumor immune microenvironment is yet to be clarified. The Cancer Genome Atlas database and Genotype-Tissue Expression database were used to analyze the differential expression of WFDC3 between the tumor and adjacent tissues. The clinical significance of WFDC3 was analyzed in The Cancer Genome Atlas and International Cancer Genome Consortium database using WFDC3 transcripts and clinical information. In order to elucidate the underlying mechanisms, gene set enrichment analysis was conducted to determine potential activated pathways. Immune score evaluation and publicly available pharmacogenomics database [the Genomics of Drug Sensitivity in Cancer] were utilized to quantify immune cell infiltration and the effect on chemotherapeutic drug sensitivity. WFDC3 levels were higher in PAAD tissues than in normal pancreatic tissues. High levels of WFDC3 expression progressively increased as PAAD tumor stages progressed. Patients with elevated WFDC3 expression showed a poor prognosis. The gene set enrichment analysis analysis revealed that glutamate, arginine, and proline, and histidine metabolism levels were elevated in patients with a high WFDC3 expression phenotype. B, CD4+ T, and CD8+ T cell infiltration was diminished in PAAD tissues with elevated WFDC3 expression. According to pharmacogenomics, PAAD tissues with high WFDC3 expression are susceptible to gemcitabine. WFDC3 is highly expressed in PAAD, and patients with a high level of WFDC3 expression have a shorter overall survival time, indicating a poorer prognosis. High expression of WFDC3 may lead to the development of PAAD by affecting the amino acid metabolism and the tumor immunological microenvironment. WFDC3 may serve as a potential diagnostic and prognostic biomarker for PAAD patients.

Research progress on the role of cationic amino acid transporter (CAT) family members in malignant tumors and immune microenvironment

Amino acids are essential for the survival of all living organisms and living cells. Amino acid transporters mediate the transport and absorption of amino acids, and the dysfunction of these proteins can induce human diseases. Cationic amino acid transporters (CAT family, SLC7A1-4, and SLC7A14) are considered to be a group of transmembrane transporters, of which SLC7A1-3 are essential for arginine transport in mammals. Numerous studies have shown that CAT family-mediated arginine transport is involved in signal crosstalk between malignant tumor cells and immune cells, especially T cells. The modulation of extracellular arginine concentration has entered a number of clinical trials and achieved certain therapeutic effects. Here, we review the role of CAT family on tumor cells and immune infiltrating cells in malignant tumors and explore the therapeutic strategies to interfere with extracellular arginine concentration, to elaborate its application prospects. CAT family members may be used as biomarkers for certain cancer entities and might be included in new ideas for immunotherapy of malignant tumors.

The role of bone marrow microenvironment (BMM) cells in acute myeloid leukemia (AML) progression: immune checkpoints, metabolic checkpoints, and signaling pathways

Acute myeloid leukemia (AML) comprises a multifarious and heterogeneous array of illnesses characterized by the anomalous proliferation of myeloid cells in the bone marrow microenvironment (BMM). The BMM plays a pivotal role in promoting AML progression, angiogenesis, and metastasis. The immune checkpoints (ICs) and metabolic processes are the key players in this process. In this review, we delineate the metabolic and immune checkpoint characteristics of the AML BMM, with a focus on the roles of BMM cells e.g. tumor-associated macrophages, natural killer cells, dendritic cells, metabolic profiles and related signaling pathways. We also discuss the signaling pathways stimulated in AML cells by BMM factors that lead to AML progression. We then delve into the roles of immune checkpoints in AML angiogenesis, metastasis, and cell proliferation, including co-stimulatory and inhibitory ICs. Lastly, we discuss the potential therapeutic approaches and future directions for AML treatment, emphasizing the potential of targeting metabolic and immune checkpoints in AML BMM as prognostic and therapeutic targets. In conclusion, the modulation of these processes through the use of directed drugs opens up new promising avenues in combating AML. Thereby, a comprehensive elucidation of the significance of these AML BMM cells' metabolic and immune checkpoints and signaling pathways on leukemic cells can be undertaken in the future investigations. Additionally, these checkpoints and cells should be considered plausible multi-targeted therapies for AML in combination with other conventional treatments in AML. Video Abstract.

Aspartic Acid in Health and Disease

Aspartic acid exists in L- and D-isoforms (L-Asp and D-Asp). Most L-Asp is synthesized by mitochondrial aspartate aminotransferase from oxaloacetate and glutamate acquired by glutamine deamidation, particularly in the liver and tumor cells, and transamination of branched-chain amino acids (BCAAs), particularly in muscles. The main source of D-Asp is the racemization of L-Asp. L-Asp transported via aspartate-glutamate carrier to the cytosol is used in protein and nucleotide synthesis, gluconeogenesis, urea, and purine-nucleotide cycles, and neurotransmission and via the malate-aspartate shuttle maintains NADH delivery to mitochondria and redox balance. L-Asp released from neurons connects with the glutamate-glutamine cycle and ensures glycolysis and ammonia detoxification in astrocytes. D-Asp has a role in brain development and hypothalamus regulation. The hereditary disorders in L-Asp metabolism include citrullinemia, asparagine synthetase deficiency, Canavan disease, and dicarboxylic aminoaciduria. L-Asp plays a role in the pathogenesis of psychiatric and neurologic disorders and alterations in BCAA levels in diabetes and hyperammonemia. Further research is needed to examine the targeting of L-Asp metabolism as a strategy to fight cancer, the use of L-Asp as a dietary supplement, and the risks of increased L-Asp consumption. The role of D-Asp in the brain warrants studies on its therapeutic potential in psychiatric and neurologic disorders.

Drug Repurposing to Circumvent Immune Checkpoint Inhibitor Resistance in Cancer Immunotherapy

Immune checkpoint inhibitors (ICI) have achieved unprecedented clinical success in cancer treatment. However, drug resistance to ICI therapy is a major hurdle that prevents cancer patients from responding to the treatment or having durable disease control. Drug repurposing refers to the application of clinically approved drugs, with characterized pharmacological properties and known adverse effect profiles, to new indications. It has also emerged as a promising strategy to overcome drug resistance. In this review, we summarized the latest research about drug repurposing to overcome ICI resistance. Repurposed drugs work by either exerting immunostimulatory activities or abolishing the immunosuppressive tumor microenvironment (TME). Compared to the de novo drug design strategy, they provide novel and affordable treatment options to enhance cancer immunotherapy that can be readily evaluated in the clinic. Biomarkers are exploited to identify the right patient population to benefit from the repurposed drugs and drug combinations. Phenotypic screening of chemical libraries has been conducted to search for T-cell-modifying drugs. Genomics and integrated bioinformatics analysis, artificial intelligence, machine and deep learning approaches are employed to identify novel modulators of the immunosuppressive TME.

Diagnostic Value of Salivary Amino Acid Levels in Cancer

This review analyzed 21 scientific papers on the determination of amino acids in various types of cancer in saliva. Most of the studies are on oral cancer (8/21), breast cancer (4/21), gastric cancer (3/21), lung cancer (2/21), glioblastoma (2/21) and one study on colorectal, pancreatic, thyroid and liver cancer. The amino acids alanine, valine, phenylalanine, leucine and isoleucine play a leading role in the diagnosis of cancer via the saliva. In an independent version, amino acids are rarely used; the authors combine either amino acids with each other or with other metabolites, which makes it possible to obtain high values of sensitivity and specificity. Nevertheless, a logical and complete substantiation of the changes in saliva occurring in cancer, including changes in salivary amino acid levels, has not yet been formed, which makes it important to continue research in this direction.

Co-inhibition of glutaminolysis and one-carbon metabolism promotes ROS accumulation leading to enhancement of chemotherapeutic efficacy in anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is one of the most aggressive tumors with an extremely poor prognosis. Based on the several biological features related to glutamine metabolism in ATC, we hypothesized glutaminolysis inhibition induces cell death in ATC cells. However, glutamine metabolism inhibition triggered cell growth arrest independent of cell death in ATC, suggesting that other signaling pathways avoid glutamine metabolism inhibition-induced stress exist. To investigate the functional mechanism against glutamine metabolism inhibition, we conducted mRNA and ATAC-Sequencing data analysis and found that glutamine deprivation increased ATF4-mediated one-carbon metabolism. When we inhibited PHGDH, the first rate-limiting enzyme for one-carbon metabolism, cell growth arrest was promoted upon glutamine metabolism inhibition by accumulating intracellular ROS. We next observed that the co-inhibition of glutamine and one-carbon metabolism could augment the anticancer effects of drugs used in patients with ATC. Finally, single-cell RNA sequencing analysis revealed that one-carbon metabolism was strengthened through the evolutionary process from PTC to ATC. Collectively, our data demonstrate that one-carbon metabolism has a potential role of modulation of cell fate in metabolic stress and can be a therapeutic target for enhancing antitumor effects in ATC.