Supply and demand: Cellular nutrient uptake and exchange in cancer

Identification of oncogenes associated with colorectal cancer mortality and the effect of cinnamon-conjugated magnetic nanoparticles on their expression

Finding the molecular targets involved in the severity and drug resistance of Colorectal cancer (CRC) and applying targeted treatments against them is a promising approach. In this study, some candidate oncogenes related to disease severity and mortality were identified by extracting bioinformatics data, and the effect of Fe3O4@Glu-Cinnamon NPs on the survival of CRC cells (SW480) and the expression of these oncogenes was investigated. The NPs were characterized by FT-IR, XRD, DLS and zeta potential measurement, TEM and SEM imaging, EDS-mapping and VSM analysis. Cytotoxicity of the NPs was evaluated by the MTT assay and a flow cytometry analysis was done to investigate cell apoptosis/necrosis levels and cell cycle analysis of cancer cells. The Fe3O4@Glu-Cinnamon NPs with spherical morphology were correctly synthesized, containing no elemental impurities, with a size range of 26.8-60.2 nm, DLS of 213 nm, zeta potential of -15.4mV and maximum magnetization level of 20.33emu/g. Treatment of cancer cells with the NPs elevated primary and late apoptosis and cell necrosis levels to 20.85, 16.83 and 9.56% and treated cells were mainly arrested at the S and G2/M phases. The expression level of the oncogenes associated with mortality, SNAI1, THBS2 and INHBA reduced to 0.74, 0.66 and 0.7 folds, respectively. The magnetic properties of Fe3O4 NPs enable their potential use in targeted drug delivery, allowing for site-specific accumulation within tumors. This could minimize systemic toxicity while enhancing treatment efficacy.

The metabolic underpinnings of sebaceous lipogenesis

Sebaceous glands synthesize and secrete sebum, a mélange of lipids and other cellular products that safeguards the mammalian integument. Differentiating sebocytes delaminate from the basal membrane and dislodge towards the gland's middle, where they eventually undergo a poorly understood death mode in which the whole cell becomes a secretion product (holocrine secretion). Supported by recent transcriptomics data, this review examines the idea that peripheral sebocytes have a remarkable ability to draw nutrients from the blood and become committed to unrestrainedly invest all available resources into synthetic processes for accomplishing sebum synthesis, thereby exploiting core metabolic fluxes as glycogen turnover, glutamine-directed anaplerosis, the pentose phosphate pathway and de novo lipogenesis. Finally, we propose that metabolic-driven processes are an important mechanistic component of holocrine secretion. A deeper understanding of these metabolic adaptations could indicate novel strategies for modulating sebum synthesis, a key pathogenic factor in acne and other skin diseases.

NR4A1 suppresses breast cancer growth by repressing c-Fos-mediated lipid and redox dyshomeostasis

The specific function of NR4A1 as a transcriptional regulator in cancer remains unclear. Here we report the biological effect of NR4A1 in suppressing breast cancer (BC) growth. We found that NR4A1 deficiency was correlated with BC progression in the clinic. Genetic deletion of NR4A1 in BC cells significantly promoted cellular proliferation and tumor growth. Moreover, global metabolome screening indicated that the deletion of NR4A1 resulted in tumor lipid remodeling and phospholipid accumulation, which was accompanied by increases in fatty acid and lipid uptake. In addition, NR4A1 knockout induced oxidative stress that aggravated redox balance disruption. Mechanistically, transcriptomic and epigenomic analyses revealed that NR4A1 restrained BC cell proliferation by directly interacting with c-Fos and competitively inhibiting c-Fos binding to the promoter of the target gene PRDX6, which is involved in lipid and redox homeostasis. Notably, we confirmed that the treatment of BC cells with the selective NR4A1 agonist cytosporone B significantly activated the expression of NR4A1, followed by increased interaction between NR4A1 and c-Fos, thereby interfering with c-Fos-mediated transcriptional regulation of BC cell growth. Thus, NR4A1 plays a vital role in reducing the c-Fos-induced activation of downstream signaling cascades in BC, suggesting that agents that activate NR4A1 may be potential therapeutic strategies.

Dietary nutrient intake and cancer presence: evidence from a cross-sectional study

BACKGROUND

While the role of specific nutrients in cancer is established, associations between comprehensive between dietary nutrient intake and cancer presence remain underexplored. This cross-sectional study investigates global dietary nutrient profiles in relation to solid and blood cancers.

METHODS

A total of 42,732 mobile adults from the National Health and Nutrition Examination Survey (NHANES, 2001-2023) were enrolled in this study. The potential associations of dietary intakes of 34 nutrients and 4 common trace components with cancer presence were investigated by weighted logistic regression and restricted cubic spline.

RESULTS

Higher intake of saturated fatty acid (OR = 1.1082, 95% CI: 1.0110-1.2146), β-carotene (OR = 1.0431, 1.0096-1.0777) and vitamin K (OR = 1.0370, 1.0094-1.0654) was positively associated with overall cancer presence, while phosphorus intake (OR = 0.9016, 0.8218-0.9892) showed a protective association. For solid tumors, dietary intakes of saturated fatty acid (OR = 1.1099), α-carotene (OR = 1.0353), β-carotene (OR = 1.0484), and vitamin K (OR = 1.0405) exhibited positive associations. Retinol intake was linked to blood carcinoma (OR = 1.0935, 1.0222-1.1698). Dose-response analyses revealed linear relationships without non-linear thresholds.

CONCLUSION

Specific dietary nutrients, notably saturated fats, carotenoids, and vitamin K, are associated with increased cancer presence, whereas phosphorus intake is associated with the reduced cancer presence. Due to the cross-sectional nature of the study and the measurement of dietary intake after cancer diagnosis, a causal relationship could not be established. These findings underscore the need for longitudinal studies to establish causality and inform dietary interventions in cancer management.

Reprogramming of Thyroid Cancer Metabolism: from Mechanism to Therapeutic Strategy

Thyroid cancer as one of the most prevalent malignancies of endocrine system, has raised public concern and more research on its mechanism and treatment. And metabolism-based therapies have advanced rapidly, for the exclusive metabolic profiling of thyroid cancer. In thyroid cancer cells, plenty of metabolic pathways are reprogrammed to accommodate tumor microenvironment. In this review, we initiatively summarize recent progress in the full-scale thyroid cancer metabolic rewiring and the interconnection of various metabolites. We also discuss the efficacy and prospect of metabolic targeted detection as well as therapy. Comprehending metabolic mechanism and characteristics of thyroid cancer roundly will be highly beneficial to managing individual patients.

Rational design of peptides to overcome drug resistance by metabolic regulation

Chemotherapy is widely used clinically, however, its efficacy is often compromised by the development of drug resistance, which arises from prolonged administration of drugs or other stimuli. One of the driven causes of drug resistance in tumors or bacterial infections is metabolic reprogramming, which alters mitochondrial metabolism, disrupts metabolic pathways and causes ion imbalance. Bioactive peptide materials, due to their biocompatibility, diverse bioactivities, customizable sequences, and ease of modification, have shown promise in overcoming drug resistance. This review provides an in-depth analysis of metabolic reprogramming and associated microenvironmental changes that contribute to drug resistance in common tumors and bacterial infections, suggesting potential therapeutic targets. Additionally, we explore peptide-based materials for regulating metabolism and their potential synergic effect with other therapies, highlighting the mechanisms by which these peptides reverse drug resistance. Finally, we discuss future perspectives and the clinical challenges in peptide-based treatments, aiming to offer insights for overcoming drug-resistant diseases.

Defined media reveals the essential role of lipid scavenging to support cancer cell proliferation

Fetal bovine serum (FBS) is a nearly ubiquitous, yet undefined additive in mammalian cell culture media whose functional contributions to promoting cell proliferation remain poorly understood. Efforts to replace serum supplementation in culture media have been hindered by an incomplete understanding of the environmental requirements fulfilled by FBS in culture. Here, we use a combination of live-cell imaging and liquid chromatography-mass spectrometry to elucidate the role of serum in supporting proliferation. We show that serum provides consumed factors that enable proliferation and demonstrate that the serum metal and lipid components are crucial to sustaining proliferation in culture. Importantly, despite access to a wide range of lipid classes, albumin-bound lipids are the primary species consumed during cancer cell proliferation. Furthermore, we find that combinations of the additive ITS, containing necessary metals, and albumin-associated lipid classes are sufficient to replace FBS in culture media. We show that serum-free media enables sensitive quantification of lipid consumption dynamics during cell proliferation, which indicate that fatty acids (FA) are consumed through a mass-action mechanism, with minimal competition from other lipid classes. Finally, we find that pharmacologic disruption of FA activation and incorporation into the cellular lipidome reduces uptake from the environment and impairs cell proliferation. This work therefore identifies metabolic contributions of serum in cell culture settings and provides a framework for building cell culture systems that sustain cell proliferation without the variable and undefined contributions of FBS.

Envisioning Glucose Transporters (GLUTs and SGLTs) as Novel Intervention against Cancer: Drug Discovery Perspective and Targeting Approach

Metabolic reprogramming and altered cellular energetics have been recently established as an important cancer hallmark. The modulation of glucose metabolism is one of the important characteristic features of metabolic reprogramming in cancer. It contributes to oncogenic progression by supporting the increased biosynthetic and bio-energetic demands of tumor cells. This oncogenic transformation consequently results in elevated expression of glucose transporters in these cells. Moreover, various cancers exhibit abnormal transporter expression patterns compared to normal tissues. Recent investigations have underlined the significance of glucose transporters in regulating cancer cell survival, proliferation, and metastasis. Abnormal regulation of these transporters, which exhibit varying affinities for hexoses, could enable cancer cells to efficiently manage their energy supply, offering a crucial edge for proliferation. Exploiting the upregulated expression of glucose transporters, GLUTs, and Sodium Linked Glucose Transporters (SGLTs), could serve as a novel therapeutic intervention for anti-cancer drug discovery as well as provide a unique targeting approach for drug delivery to specific tumor tissues. This review aims to discussthe previous and emerging research on the expression of various types of glucose transporters in tumor tissues, the role of glucose transport inhibitors as a cancer therapy intervention as well as emerging GLUT/SGLT-mediated drug delivery strategies that can be therapeutically employed to target various cancers.

An early, novel arginine methylation of KCa3.1 attenuates subsequent T cell exhaustion

T cell receptor (TCR) engagement initiates the activation process, and this signaling event is regulated in multifaceted ways. Nutrient availability in the immediate niche is one such mode of regulation 1-3 . Here, we investigated how the availability of an essential amino acid methionine (Met) and TCR signaling might interplay in the earliest events of T cell activation to affect subsequent T cell fate and function. We found that limiting Met during only the initial 30 minutes of CD8 + T cell activation increased Ca 2+ influx, Ca 2+ -mediated NFAT1 ( Nfatc2 ) activation, NFAT1 promoter occupancy, and T cell exhaustion. We identified changes in the protein arginine methylome during the initial 30 min of TCR engagement and discovered a novel arginine methylation of a Ca 2+ -activated potassium transporter, KCa3.1, which regulates Ca 2+ -mediated NFAT1 signaling to ensure optimal activation. Ablation of arginine methylation in KCa3.1 led to increased NFAT1 activation, rendering T cells dysfunctional in murine tumour and infection models. Furthermore, acute Met supplementation at early stages reduced nuclear NFAT1 in tumour-infiltrating T cells and augmented their anti-tumour activity. Our findings identify a metabolic event occurring early after T cell activation that influences the subsequent fate of the cell.

Nutritional Glutamine-Modified Iron-Delivery System with Enhanced Endocytosis for Ferroptosis Therapy of Pancreatic Tumors

Heterogeneous reprogrammed nutrient metabolic networks formed by oncogenes exhibit the potential for exploring novel druggable targets and developing innovative anticancer therapeutics. Herein, based on the heterogeneous metabolic characteristics of glutamine (Gln) addiction in pancreatic cancer cells, an iron-delivery system (IDS) with enhanced endocytosis is designed for efficient ferroptosis therapy. The IDS is characterized by Gln modification and can be recognized as a source of Gln nutrients for efficient endocytic uptake by pancreatic tumor cells. Because the IDS is flexible to combine with amino acid-like components, the IDS with enhanced endocytosis is further produced by loading the Gln transporter inhibitor of V9302. V9302 is capable of suppressing molecular Gln uptake via transporter ASCT2, which generates Gln deprivation to direct metabolic reprogramming of cancer cells and enhances cellular uptake of Gln-modified IDS via RAS-stimulated macropinocytosis. The enhanced endocytosis and high iron content of IDS facilitate ferroptosis in mice pancreatic tumor models; thus, an amino acid-like ferroptosis inducer of l-buthionine sulfoximine (BSO) is further combined. The enhanced endocytosis resulting from the synergism of Gln and V9302 enables the efficient delivery of iron and BSO for ferroptosis tumor therapy. This work provides an alternative approach for enhancing intracellular drug delivery of the tumors with heterogeneous nutrient metabolism by virtue of combining nutrient-modified nanodrugs with the corresponding nutrient transporter inhibitors.

Advancing drug discovery through assay development: a survey of tool compounds within the human solute carrier superfamily

With over 450 genes, solute carriers (SLCs) constitute the largest transporter superfamily responsible for the uptake and efflux of nutrients, metabolites, and xenobiotics in human cells. SLCs are associated with a wide variety of human diseases, including cancer, diabetes, and metabolic and neurological disorders. They represent an important therapeutic target class that remains only partly exploited as therapeutics that target SLCs are scarce. Additionally, many small molecules reported in the literature to target SLCs are poorly characterized. Both features may be due to the difficulty of developing SLC transport assays that fulfill the quality criteria for high-throughput screening. Here, we report one of the main limitations hampering assay development within the RESOLUTE consortium: the lack of a resource providing high-quality information on SLC tool compounds. To address this, we provide a systematic annotation of tool compounds targeting SLCs. We first provide an overview on RESOLUTE assays. Next, we present a list of SLC-targeting compounds collected from the literature and public databases; we found that most data sources lacked specificity data. Finally, we report on experimental tests of 19 selected compounds against a panel of 13 SLCs from seven different families. Except for a few inhibitors, which were active on unrelated SLCs, the tested inhibitors demonstrated high selectivity for their reported targets. To make this knowledge easily accessible to the scientific community, we created an interactive dashboard displaying the collected data in the RESOLUTE web portal (https://re-solute.eu). We anticipate that our open-access resources on assays and compounds will support the development of future drug discovery campaigns for SLCs.

Oncogenic KRAS Induces Arginine Auxotrophy and Confers a Therapeutic Vulnerability to SLC7A1 Inhibition in Non-Small Cell Lung Cancer

The urea cycle is frequently rewired in cancer cells to meet the metabolic demands of cancer. Elucidation of the underlying mechanism by which oncogenic signaling mediates urea cycle reprogramming could help identify targetable metabolic vulnerabilities. In this study, we discovered that oncogenic activation of KRAS in non-small cell lung cancer (NSCLC) silenced the expression of argininosuccinate synthase 1 (ASS1), a urea cycle enzyme that catalyzes the production of arginine from aspartate and citrulline, and thereby diverted the utilization of aspartate to pyrimidine synthesis to meet the high demand for DNA replication. Specifically, KRAS signaling facilitated a hypoacetylated state in the promoter region of the ASS1 gene in a histone deacetylase 3-dependent manner, which in turn impeded the recruitment of c-MYC for ASS1 transcription. ASS1 suppression in KRAS-mutant NSCLC cells impaired the biosynthesis of arginine and rendered a dependency on the arginine transmembrane transporter SLC7A1 to import extracellular arginine. Depletion of SLC7A1 in both patient-derived organoid and xenograft models inhibited KRAS-driven NSCLC growth. Together, these findings uncover the role of oncogenic KRAS in rewiring urea cycle metabolism and identify SLC7A1-mediated arginine uptake as a therapeutic vulnerability for treating KRAS-mutant NSCLC.

SIGNIFICANCE

ASS1 deficiency is induced by mutant KRAS in NSCLC to facilitate DNA synthesis and creates a dependency on SLC7A1, revealing dietary arginine restriction and SLC7A1 inhibition as potential therapeutic strategies.

Apoptosis Induction by ZnFe2O4-Ag Biosynthesized by Chlorella vulgaris in MCF-7 Breast Cancer Cell Line

The incidence and mortality of breast cancer are growing which indicates the inefficiency of the current chemotherapy drugs. Due to the anticancer potential of Zn and Ag and the magnetic feature of iron oxide, in this work, we synthesized ZnFe2O4-Ag nanocomposite using Chlorella vulgaris and investigated its anticancer effect on breast cancer cell line. Physicochemical characterization was performed by FT-IR, XRD, SEM, TEM, VSM, EDS mapping, UV, and zeta potential assays. Cell cytotoxicity and apoptosis frequency were studied by the MTT and flow cytometry assays. Also, cell cycle analysis, Hoechst staining, and measuring ROS (reactive oxygen species) level were performed. The synthesized particles were almost spherical with a size range of 14-52 nm. The FT-IR and XRD assays confirmed the proper synthesis of the particles and VSM analysis showed that particles had magnetic property and the maximum saturation magnetization was 0.8 Emu/g. Also, the EDS mapping of the nanocomposite showed the Zn, Fe, O, and Ag elements. The MTT assay showed that the 50% inhibitory concentration (IC50) of ZnFe2O4-Ag for breast cancer and normal cells were 28 and 154 µg/mL, respectively, and the nanocomposite had stronger anticancer activity than cisplatin (IC50 = 84 µg/mL). Flow cytometry analysis showed that the exposure to the nanocomposite induced cell apoptosis by 77.5% and significantly induced ROS generation. Also, treating breast cancer cells with the nanocomposite induced cell cycle arrest and apoptotic features, including chromatin condensation and fragmentation. In conclusion, ZnFe2O4-Ag nanocomposite synthesized by C. vulgaris could suppress the proliferation of breast cancer cells by the generation of oxidative stress, apoptosis induction, and cell cycle arrest.

A rapid and simple non-radioactive assay for measuring uptake by solute carrier transporters

Introduction: Solute carrier (SLC) transport proteins play a crucial role in maintaining cellular nutrient and metabolite homeostasis and are implicated in various human diseases, making them potential targets for therapeutic interventions. However, the study of SLCs has been limited due to the lack of suitable tools, particularly cell-based substrate uptake assays, necessary for understanding their biological functions and for drug discovery purposes. Methods: In this study, a cell-based uptake assay was developed using a stable isotope-labeled compound as the substrate for SLCs, with detection facilitated by liquid chromatography-tandem mass spectrometry (LC-MS/MS). This assay aimed to address the limitations of existing assays, such as reliance on hazardous radiolabeled substrates and limited availability of fluorescent biosensors. Results: The developed assay was successfully applied to detect substrate uptakes by two specific SLCs: L-type amino acid transporter 1 (LAT1) and sodium taurocholate co-transporting polypeptide (NTCP). Importantly, the assay demonstrated comparable results to the radioactive method, indicating its reliability and accuracy. Furthermore, the assay was utilized to screen for novel inhibitors of NTCP, leading to the identification of a potential NTCP inhibitor compound. Discussion: The findings highlight the utility of the developed cell-based uptake assay as a rapid, simple, and environmentally friendly tool for investigating SLCs' biological roles and for drug discovery purposes. This assay offers a safer alternative to traditional methods and has the potential to contribute significantly to advancing our understanding of SLC function and identifying therapeutic agents targeting SLC-mediated pathways.

Comprehensive analyses of solute carrier family members identify SLC12A2 as a novel therapy target for colorectal cancer

As the largest transporter family impacting on tumor genesis and development, the prognostic value of solute carrier (SLC) members has not been elucidated in colorectal cancer (CRC). We aimed to identify a prognostic signature from the SLC members and comprehensively analyze their roles in CRC. Firstly, we downloaded transcriptome data and clinical information of CRC samples from GEO (GSE39582) and TCGA as training and testing dataset, respectively. We extracted the expression matrix of SLC genes and established a prognostic model by univariate and multivariate Cox regression. Afterwards, the low-risk and high-risk group were identified. Then, the differences of prognosis traits, transcriptome features, clinical characteristics, immune infiltration and drug sensitivity between the two groups were explored. Furthermore, molecular subtyping was also implemented by non-negative matrix factorization (NMF). Finally, we studied the expression of the screened SLC genes in CRC tumor tissues and normal tissues as well as investigated the role of SLC12A2 by loss of function and gain of function. As a result, we developed a prognostic risk model based on the screened 6-SLC genes (SLC39A8, SLC2A3, SLC39A13, SLC35B1, SLC4A3, SLC12A2). Both in the training and testing sets, CRC patients in the high-risk group had the poorer prognosis and were in the more advanced pathological stage. What's more, the high-risk group were enriched with CRC progression signatures and immune infiltration. Two groups showed different drug sensitivity. On the other hand, two distinct subclasses (C1 and C2) were identified based on the 6 SLC genes. CRC patients in the high-risk group and C1 subtype had a worse prognosis. Furthermore, we found and validated that SLC12A2 was steadily upregulated in CRC. A loss-of-function study showed that knockdown of SLC12A2 expression restrained proliferation and stemness of CRC cells while a gain-of-function study showed the contrary results. Hence, we provided a 6-SLC gene signature for prognosis prediction of CRC patients. At the same time, we identified that SLC12A2 could promote tumor progression in CRC, which may serve as a potential therapeutic target.

Enhanced anti-tumor activity of arginine decarboxylase through the incorporation of aromatic amino acids at the multimer-forming interface

The pressing challenge of cancer's high mortality and invasiveness demands improved therapeutic approaches. Targeting the nutrient dependencies within cancer cells has emerged as a promising approach. This study is dedicated to demonstrating the potential of arginine depletion for cancer treatment. Notably, the focus centers on arginine decarboxylase (RDC), a pH-dependent enzyme expecting enhanced activity within the slightly acidic microenvironments of tumors. To investigate the effect of a single-site mutation on the catalytic efficacy of RDC, diverse amino acids, including glycine, alanine, phenylalanine, tyrosine, tryptophan, p-azido-phenylalanine, and a phenylalanine analog with a hydrogen-substituted tetrazine, were introduced at the crucial threonine site (position 39) in the multimer-forming interface. Remarkably, the introduction of either a natural or a non-natural aromatic amino acid at position 39 substantially boosted enzymatic activity, while amino acids with smaller side chains did not show the same effect. This enhanced enzymatic activity is likely attributed to the reinforced formation of multimer structures through favorable interactions between the introduced aromatic amino acid and the neighboring subunit. Noteworthy, at slightly acidic pH, the RDC variant featuring tryptophan at position 39 demonstrated augmented cytotoxicity against tumor cells compared to the wild-type RDC. This attribute aligns with the tumor microenvironment and positions these variants as potential candidates for targeted cancer therapy.

Mass spectrometry-based methods for investigating the dynamics and organization of the surfaceome: exploring potential clinical implications

INTRODUCTION

Cell-surface proteins are extremely important for many cellular events, such as regulating cell-cell communication and cell-matrix interactions. Aberrant alterations in surface protein expression, modification (especially glycosylation), and interactions are directly related to human diseases. Systematic investigation of surface proteins advances our understanding of protein functions, cellular activities, and disease mechanisms, which will lead to identifying surface proteins as disease biomarkers and drug targets.

AREAS COVERED

In this review, we summarize mass spectrometry (MS)-based proteomics methods for global analysis of cell-surface proteins. Then, investigations of the dynamics of surface proteins are discussed. Furthermore, we summarize the studies for the surfaceome interaction networks. Additionally, biological applications of MS-based surfaceome analysis are included, particularly highlighting the significance in biomarker identification, drug development, and immunotherapies.

EXPERT OPINION

Modern MS-based proteomics provides an opportunity to systematically characterize proteins. However, due to the complexity of cell-surface proteins, the labor-intensive workflow, and the limit of clinical samples, comprehensive characterization of the surfaceome remains extraordinarily challenging, especially in clinical studies. Developing and optimizing surfaceome enrichment methods and utilizing automated sample preparation workflow can expand the applications of surfaceome analysis and deepen our understanding of the functions of cell-surface proteins.

Phenotypic profiling of solute carriers characterizes serine transport in cancer

Serine is a vital amino acid in tumorigenesis. While cells can perform de novo serine synthesis, most transformed cells rely on serine uptake to meet their increased biosynthetic requirements. Solute carriers (SLCs), a family of transmembrane nutrient transport proteins, are the gatekeepers of amino acid acquisition and exchange in mammalian cells and are emerging as anticancer therapeutic targets; however, the SLCs that mediate serine transport in cancer cells remain unknown. Here we perform an arrayed RNAi screen of SLC-encoding genes while monitoring amino acid consumption and cell proliferation in colorectal cancer cells using metabolomics and high-throughput imaging. We identify SLC6A14 and SLC25A15 as major cytoplasmic and mitochondrial serine transporters, respectively. We also observe that SLC12A4 facilitates serine uptake. Dual targeting of SLC6A14 and either SLC25A15 or SLC12A4 diminishes serine uptake and growth of colorectal cancer cells in vitro and in vivo, particularly in cells with compromised de novo serine biosynthesis. Our results provide insight into the mechanisms that contribute to serine uptake and intracellular handling.

Trigger of apoptosis in human liver cancer cell line (HepG2) by titanium dioxide nanoparticles functionalized by glutamine and conjugated with thiosemicarbazone

The incidence of liver cancer, the third cause of cancer-associated death, has been growing, worldwide. The increasing trend of liver cancer incidence and mortality indicates the inefficiency of current therapeutic approaches, especially anticancer chemotherapy. Owing to the promising anticancer potential of Thiosemicarbazone (TSC) complexes, this work was conducted to synthesize titanium oxide nanoparticles conjugated with TSC through glutamine functionalization (TiO2@Gln-TSC NPs) and characterize their anticancer mechanism in HepG2 liver cancer cells. Physicochemical analyses of the synthesized particles, including FT-IR, XRD, SEM, TEM, Zeta potential and DLS, and EDS-mapping confirmed the proper synthesis and conjugation of TiO2@Gln-TSC NPs. The synthesized NPs were almost spherical, with a size range of 10-80 nm, a zeta potential of - 57.8 mV, a hydrodynamic size of 127 nm, and without impurities. Investigation of the cytotoxic effect of TiO2@Gln-TSC in HepG2 and HEK293 human normal cells indicated significantly higher toxicity in cancer cells (IC50 = 75 µg/mL) than normal cells (IC50 = 210 µg/mL). Flow cytometry analysis of TiO2@Gln-TSC treated and control cells showed that the population of apoptotic cells considerably increased from 2.8 to 27.3% after treatment with the NPs. Moreover, 34.1% of the TiO2@Gln-TSC treated cells were mainly arrested at the sub-G1 phase of the cell cycle, which was significantly greater than control cells (8.4%). The Hoechst staining assay showed considerable nuclear damage, including chromatin fragmentation and the appearance of apoptotic bodies. This work introduced TiO2@Gln-TSC NPs as a promising anticancer compound that could combat liver cancer cells through apoptosis induction.

Plasma metabolomics of oral squamous cell carcinomas based on NMR and MS approaches provides biomarker identification and survival prediction

Metabolomics has proven to be an important omics approach to understand the molecular pathways underlying the tumour phenotype and to identify new clinically useful markers. The literature on cancer has illustrated the potential of this approach as a diagnostic and prognostic tool. The present study aimed to analyse the plasma metabolic profile of patients with oral squamous cell carcinoma (OSCC) and controls and to compare patients with metastatic and primary tumours at different stages and subsites using nuclear magnetic resonance and mass spectrometry. To our knowledge, this is the only report that compared patients at different stages and subsites and replicates collected in diverse institutions at different times using these methodologies. Our results showed a plasma metabolic OSCC profile suggestive of abnormal ketogenesis, lipogenesis and energy metabolism, which is already present in early phases but is more evident in advanced stages of the disease. Reduced levels of several metabolites were also associated with an unfavorable prognosis. The observed metabolomic alterations may contribute to inflammation, immune response inhibition and tumour growth, and may be explained by four nonexclusive views-differential synthesis, uptake, release, and degradation of metabolites. The interpretation that assimilates these views is the cross talk between neoplastic and normal cells in the tumour microenvironment or in more distant anatomical sites, connected by biofluids, signalling molecules and vesicles. Additional population samples to evaluate the details of these molecular processes may lead to the discovery of new biomarkers and novel strategies for OSCC prevention and treatment.

Elevated serum β-hydroxybutyrate, a circulating ketone metabolite, accelerates colorectal cancer proliferation and metastasis via ACAT1

Colorectal cancer (CRC) ranks third in incidence and second in mortality worldwide. Metabolic disorders are known to be closely associated with CRC. Functional metabolomics aims to translate metabolomics-derived biomarkers to disease mechanisms. Previous work based on untargeted liquid chromatography identified 30 differential metabolites of CRC. Among them, only β-hydroxybutyrate (BHB) was elevated in CRC. Here, we first confirm the increased level of β-hydroxybutyrate by targeted metabolomic analysis using an independent cohort of 400 serum samples by UPLC-QQQ-MS/MS analysis. Using appropriate cell and animal models, we find that treatment with pathological levels of β-hydroxybutyrate expedites CRC proliferation and metastasis. Out of four major rate-limiting enzymes of ketolysis, only acetyl-coenzyme A acetyltransferase1 (ACAT1) expression is increased in paired human CRC tissues. These findings suggest probable clinical relevance for the functional implications of β-hydroxybutyrate in CRC. We demonstrate that β-hydroxybutyrate may exert its tumorigenic effects via regulation of ACAT1, due to induction of downstream isocitrate dehydrogenase1 (IDH1) acetylation. Genetic silencing of ACAT1 significantly suppresses the progression of CRC and abrogates the effects of β-hydroxybutyrate both in vitro and in vivo. Overall, this study suggests that targeting β-hydroxybutyrate and its major rate-limiting enzyme ACAT1 may provide a new avenue for therapeutic intervention in CRC.

How Warburg-Associated Lactic Acidosis Rewires Cancer Cell Energy Metabolism to Resist Glucose Deprivation

Lactic acidosis, a hallmark of solid tumour microenvironment, originates from lactate hyperproduction and its co-secretion with protons by cancer cells displaying the Warburg effect. Long considered a side effect of cancer metabolism, lactic acidosis is now known to play a major role in tumour physiology, aggressiveness and treatment efficiency. Growing evidence shows that it promotes cancer cell resistance to glucose deprivation, a common feature of tumours. Here we review the current understanding of how extracellular lactate and acidosis, acting as a combination of enzymatic inhibitors, signal, and nutrient, switch cancer cell metabolism from the Warburg effect to an oxidative metabolic phenotype, which allows cancer cells to withstand glucose deprivation, and makes lactic acidosis a promising anticancer target. We also discuss how the evidence about lactic acidosis' effect could be integrated in the understanding of the whole-tumour metabolism and what perspectives it opens up for future research.

Potent Inhibition of Macropinocytosis by Niclosamide in Cancer Cells: A Novel Mechanism for the Anticancer Efficacy for the Antihelminthic

Niclosamide, a drug used to treat tapeworm infection, possesses anticancer effects by interfering with multiple signaling pathways. Niclosamide also causes intracellular acidification. We have recently discovered that the amino acid transporter SLC38A5, an amino acid-dependent Na+/H+ exchanger, activates macropinocytosis in cancer cells via amino acid-induced intracellular alkalinization. Therefore, we asked whether niclosamide will block basal and SLC38A5-mediated macropinocytosis via intracellular acidification. We monitored macropinocytosis in pancreatic and breast cancer cells using TMR-dextran and the function of SLC38A5 by measuring Li+-stimulated serine uptake. The peptide transporter activity was measured by the uptake of glycylsarcosine. Treatment of the cancer cells with niclosamide caused intracellular acidification. The drug blocked basal and serine-induced macropinocytosis with differential potency, with an EC50 of ~5 μM for the former and ~0.4 μM for the latter. The increased potency for amino acid-mediated macropinocytosis is due to direct inhibition of SLC38A5 by niclosamide in addition to the ability of the drug to cause intracellular acidification. The drug also inhibited the activity of the H+-coupled peptide transporter. We conclude that niclosamide induces nutrient starvation in cancer cells by blocking macropinocytosis, SLC38A5 and the peptide transporter. These studies uncover novel, hitherto unknown, mechanisms for the anticancer efficacy of this antihelminthic.

MicroRNAs in the Regulation of Solute Carrier Proteins Behind Xenobiotic and Nutrient Transport in Cells

Altered metabolism, such as aerobic glycolysis or the Warburg effect, has been recognized as characteristics of tumor cells for almost a century. Since then, there is accumulating evidence to demonstrate the metabolic reprogramming of tumor cells, addiction to excessive uptake and metabolism of key nutrients, to support rapid proliferation and invasion under tumor microenvironment. The solute carrier (SLC) superfamily transporters are responsible for influx or efflux of a wide variety of xenobiotic and metabolites that are needed for the cells to function, as well as some medications. To meet the increased demand for nutrients and energy, SLC transporters are frequently dysregulated in cancer cells. The SLCs responsible for the transport of key nutrients for cancer metabolism and energetics, such as glucose and amino acids, are of particular interest for their roles in tumor progression and metastasis. Meanwhile, rewired metabolism is accompanied by the dysregulation of microRNAs (miRNAs or miRs) that are small, noncoding RNAs governing posttranscriptional gene regulation. Studies have shown that many miRNAs directly regulate the expression of specific SLC transporters in normal or diseased cells. Changes of SLC transporter expression and function can subsequently alter the uptake of nutrients or therapeutics. Given the important role for miRNAs in regulating disease progression, there is growing interest in developing miRNA-based therapies, beyond serving as potential diagnostic or prognostic biomarkers. In this article, we discuss how miRNAs regulate the expression of SLC transporters and highlight potential influence on the supply of essential nutrients for cell metabolism and drug exposure toward desired efficacy.

AKR1C1 promotes non-small cell lung cancer proliferation via crosstalk between HIF-1α and metabolic reprogramming

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AKR1C1 accelerates the proliferation of NSCLC cells.

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AKR1C1 remodels metabolism in NSCLC cells.

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HIF-1α may play a vital role in AKR1C1-mediated metabolic reprogramming.

Non-small cell lung cancer (NSCLC) ranks first among cancer death worldwide. Despite efficacy and safety priority, targeted therapy only benefits ∼30% patients, leading to the unchanged survival rates for whole NSCLC patients. Metabolic reprogramming occurs to offer energy and intermediates for fuelling cancer cells proliferation. Thus, mechanistic insights into metabolic reprogramming may shed light upon NSCLC proliferation and find new proper targets for NSCLC treatment. Herein, we used loss- and gain-of-function experiments to uncover that highly expressed aldo-keto reductase family1 member C1 (AKR1C1) accelerated NSCLC cells proliferation via metabolic reprogramming. Further molecular profiling analyses demonstrated that AKR1C1 augmented the expression of hypoxia-inducible factor 1-alpha (HIF-1α), which could drive tumour metabolic reprogramming. What's more, AKR1C1 significantly correlated with HIF-1α signaling, which predicted poor prognosis for NSCLC patients. Collectively, our data display that AKR1C1 reprograms tumour metabolism to promote NSCLC cells proliferation by activating HIF-1α. These newly acquired data not only establish the specific role for AKR1C1 in metabolic reprogramming, but also hint to the possibility that AKR1C1 may be a new therapeutic target for NSCLC treatment.

Rationally designed cationic amphiphilic peptides for selective gene delivery to cancer cells

Gene therapy has gained increasing attention as an alternative to pharmacotherapy for treatment of various diseases. The extracellular and intracellular barriers to gene delivery necessitate the use of gene vectors which has led to the development of myriads of gene delivery systems. However, many of these gene delivery systems have pitfalls such as low biocompatibility, low loading efficiency, low transfection efficiency, lack of tissue selectivity and high production costs. Herein, we report the development of a new series of short cationic amphiphilic peptides with anticancer activity for selective delivery of small interfering RNA (siRNA) and antisense oligodeoxynucleotides (ODNs) to cancer cells. The peptides consist of alternating dyads of hydrophobic (isoleucine (I) or leucine (L)) and hydrophilic (arginine (R) or lysine (L)) amino acids. The peptides exhibited higher preference for transfection of HCT 116 colorectal cancer cells compared to human dermal fibroblasts (HDFs) and induced higher level of gene silencing in the cancer cells. The nucleic acid complexation and transfection efficiency of the peptides was a function of their secondary structure, their hydrophobicity and their C-terminal amino acid. The peptides containing L in their hydrophobic domain formed stronger complexes with siRNA and successfully delivered it to the cancer cells but were unable to release their cargo inside the cells and therefore could not induce any gene silencing. On the contrary, the peptides containing I in their hydrophobic domain were able to release their associated siRNA and induce considerable gene silencing in cancer cells. The peptides exhibited higher selectivity for colorectal cancer cells and induced less gene silencing in fibroblasts compared to the lipid-based commercial transfection reagent DharmaFECT™ 1. The results from this study can serve as a tool for rational design of new peptide-based gene vectors for high selective gene delivery to cancer cells.

Structural basis for recognition and transport of folic acid in mammalian cells

Structural studies on mammalian vitamin transport lag behind other metabolites. Folates, also known as B9 vitamins, are essential cofactors in one-carbon transfer reactions in biology. Three different systems control folate uptake in the human body; folate receptors function to capture and internalise extracellular folates via endocytosis, whereas two major facilitator superfamily transporters, the reduced folate carrier (RFC; SLC19A1) and proton-coupled folate transporter (PCFT; SLC46A1) control the transport of folates across cellular membranes. Targeting specific folate transporters is being pursued as a route to developing new antifolates with improved pharmacology. Recent structures of the proton-coupled folate transporter, PCFT, revealed key insights into antifolate recognition and the mechanism of proton-coupled transport. Combined with previously determined structures of folate receptors and new predictions for the structure of the RFC, we are now able to develop a structure-based understanding of folate and antifolate recognition to accelerate efforts in antifolate drug development.

Unconventional Functions of Amino Acid Transporters: Role in Macropinocytosis (SLC38A5/SLC38A3) and Diet-Induced Obesity/Metabolic Syndrome (SLC6A19/SLC6A14/SLC6A6)

Amino acid transporters are expressed in mammalian cells not only in the plasma membrane but also in intracellular membranes. The conventional function of these transporters is to transfer their amino acid substrates across the lipid bilayer; the direction of the transfer is dictated by the combined gradients for the amino acid substrates and the co-transported ions (Na⁺, H⁺, K⁺ or Cl⁻) across the membrane. In cases of electrogenic transporters, the membrane potential also contributes to the direction of the amino acid transfer. In addition to this expected traditional function, several unconventional functions are known for some of these amino acid transporters. This includes their role in intracellular signaling, regulation of acid–base balance, and entry of viruses into cells. Such functions expand the biological roles of these transporters beyond the logical amino acid homeostasis. In recent years, two additional unconventional biochemical/metabolic processes regulated by certain amino acid transporters have come to be recognized: macropinocytosis and obesity. This adds to the repertoire of biological processes that are controlled and regulated by amino acid transporters in health and disease. In the present review, we highlight the unusual involvement of selective amino acid transporters in macropinocytosis (SLC38A5/SLC38A3) and diet-induced obesity/metabolic syndrome (SLC6A19/SLC6A14/SLC6A6).