Dual Inhibition of the Lactate Transporters MCT1 and MCT4 Is Synthetic Lethal with Metformin due to NAD+ Depletion in Cancer Cells

The role of lactate metabolism in retinoblastoma tumorigenesis and ferroptosis resistance

The Warburg effect, a hallmark of cancer, describes the preference of cancer cells for glucose metabolism via aerobic glycolysis, leading to substantial lactate accumulation. However, the role of lactate metabolism in retinoblastoma, the primary intraocular malignancy in children, remains unclear. This study aimed to elucidate the gene expression profiles associated with lactate metabolism in retinoblastoma and their impact on tumorigenesis and ferroptosis resistance. The involvement of metabolic characteristics in retinoblastoma was analyzed by comparing single-cell RNA sequencing transcriptome profiles from normal retina tissues and retinoblastoma tissues from patient samples. The effects of lactate on retinoblastoma cell line viability and its mechanisms were examined both in vitro and in vivo. Single-cell RNA sequencing analysis revealed enhanced glycolysis in retinoblastoma cells and significant differences in lactate metabolism-related gene expression among various retinoblastoma cell types. Retinoblastoma cell lines with moderate lactate levels exhibited increased viability and resistance to ferroptosis induced by ferroptosis inducers. Additionally, lactate promoted the upregulation of monocarboxylate transporter 1 (MCT1), which facilitated lactate transport, in a dose-dependent manner in retinoblastoma cell lines. Knocking down MCT1 reduced both viability and ferroptosis resistance of retinoblastoma cell lines in a lactate-rich environment. In vivo, disrupting lactate transport through MCT1 inhibition suppressed retinoblastoma tumorigenesis and invasion in a mouse xenograft model, and this effect was reversed by the ferroptosis inhibitor liproxstatin-1. These findings highlighted the crucial role of lactate metabolism in retinoblastoma tumorigenesis and resistance to ferroptosis.

Targeted inhibition of JMJD2C/MALAT1 axis compensates for the deficiency of metformin in reversing ovarian cancer platinum resistance

AIMS

We explored JMJD2C's role in platinum resistance in ovarian cancer and its modulation by metformin to propose strategies for overcoming treatment limitations.

MATERIALS AND METHODS

JMJD2C and MALAT1 expression was assessed via RT-qPCR, western blotting, and immunohistochemical assays using OC cell lines, tissue from OC patients, and xenograft treatment with or without metformin. CCK-8 assays, flow cytometry, inductively coupled plasma mass spectrometry, luciferase reporter assays, and ChIP assays were employed to evaluate the impact of JMJD2C/MALAT1 on PR and the effects of metformin on JMJD2C. The effects of metformin in combination with JMJD2C knockdown were assessed in vitro and in vivo.

KEY FINDINGS

JMJD2C and MALAT1 expression was higher in tissue samples from platinum-resistant phase compared to those from paired platinum-sensitive phase. JMJD2C upregulated MALAT1 in platinum-resistant ovarian cancer (PROC) cells by demethylating its promoter at sites H3K9m3 and H3K36m3. Overexpression of JMJD2C or MALAT1 promoted PR by activating NF-κB/P-gp and P38 MAPK/ERCC1 signaling pathways, with their knockdown produced the opposite effect. Metformin increased JMJD2C expression in tumor tissue, cell lines, and a xenograft model of OC; however, elevated JMJD2C expression attenuated the PR-reversal efficacy of low-concentration metformin. Low-dose metformin combined with JMJD2C-knockdown effectively reversed PR both in in vitro and in vivo, achieving better results than either treatment alone.

SIGNIFICANCE

JMJD2C drives PR in OC by demethylating the MALAT1 promoter. Metformin upregulated JMJD2C expression, thus necessitating a higher effective dosage of metformin. Targeted inhibition of JMJD2C synergistically enhanced the efficacy of low-dose metformin in overcoming PR, thus providing a promising approach for addressing PR.

Lactate transporter MCT4 regulates the hub genes for lipid metabolism and inflammation to attenuate intracellular lipid accumulation in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) patients have multiple metabolic disturbances, with markedly elevated levels of lactate. Lactate accumulations play pleiotropic roles in disease progression through metabolic rearrangements and epigenetic modifications. Monocarboxylate transporter 4 (MCT4) is highly expressed in hepatocytes and responsible for transporting intracellular lactate out of the cell. To explore whether elevated MCT4 levels played any role in NAFLD development, we overexpressed and silenced MCT4 in hepatocytes and performed a comprehensive in vitro and in vivo analysis. Our results revealed that MCT4 overexpression down-regulated the genes for lipid synthesis while up-regulating the genes involved in lipid catabolism. Conversely, silencing MCT4 expression or inhibiting MCT4 expression led to the accumulation of intracellular lipid and glucose metabolites, resulting in hepatic steatosis. In a mouse model of NAFLD, we found that exogenous MCT4 overexpression significantly reduced lipid metabolism and alleviated hepatocellular steatosis. Mechanistically, MCT4 alleviated hepatic steatosis by regulating a group of hub genes such as Arg2, Olr1, Cd74, Mmp8, Irf7, Spp1, and Apoe, which in turn impacted multiple pathways involved in lipid metabolism and inflammatory response, such as PPAR, HIF-1, TNF, IL-17, PI3K-AKT, Wnt, and JAK-STAT. Collectively, our results strongly suggest that MCT4 may play an important role in regulating lipid metabolism and inflammation and thus serve as a potential therapeutic target for NAFLD.

G-quadruplex in cancer energy metabolism: A potential therapeutic target

In recent years, energy metabolism in cancer has received increasing attention as an important component of tumor biology, and the functions of transcription factors, mitochondria, reactive oxygen species (ROS) and the autophagy-lysosome system in which have been elucidated. G-quadruplex (G4) is a molecular switch that regulates gene transcription or translation. As an anticancer target, the effect of G4 on cancer cell proliferation, apoptosis, cycle and autophagy has been recognized. The energy metabolism system is a unified whole composed of transcription factors, metabolic regulators, metabolites and signaling pathways that run through the entire cancer process. However, the role of G4 in this complex metabolic network has not been systematically elucidated. In this review, we analyze the close correlation between G4 and transcription factors, mitochondria, ROS and the autophagy-lysosome system and suggest that G4 can exert a marked effect on cancer energy metabolism by regulating the above mentioned key regulatory elements. The anticancer effects of some G4 ligands through regulation of energy metabolism have also been summarized, confirming the clear involvement of G4 in energy metabolism. Although much more research is needed, we propose that G4 may play a critical role in the complex energy metabolism system of cancer, which is a promising target for anticancer strategies focusing on energy metabolism.

Long-term histone lactylation connects metabolic and epigenetic rewiring in innate immune memory

Trained immunity, a de facto innate immune memory characterized by enhanced responsiveness to future challenges, is underpinned by epigenetic and metabolic rewiring. In individuals vaccinated with Bacille Calmette-Guérin (BCG), lactate release was associated with enhanced cytokine responsiveness upon restimulation. Trained monocytes/macrophages are characterized by lactylation of histone H3 at lysine residue 18(H3K18la), mainly at distal regulatory regions. Histone lactylation was positively associated with active chromatin and gene transcription, persisted after the elimination of the training stimulus, and was strongly associated with "trained" gene transcription in response to a secondary stimulus. Increased lactate production upon induction of trained immunity led to enhanced production of proinflammatory cytokines, a process associated with histone lactylation. Pharmacological inhibition of lactate production or histone lactylation blocked trained immunity responses, while polymorphisms of LDHA and EP300 genes modulated trained immunity. Long-term histone lactylation persisted in vivo 90 days after vaccination with BCG, highlighting H3K18la as an epigenetic mark of innate immune memory.

Tumor-stromal metabolic crosstalk in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with a dire prognosis. Standard-of-care chemotherapy regimens offer marginal survival benefit and carry risk of severe toxicity, while immunotherapy approaches have uniformly failed in clinical trials. Extensive desmoplasia in the PDAC tumor microenvironment (TME) disrupts blood flow to and from the tumor, thereby creating a nutrient-depleted, hypoxic, and acidic milieu that suppresses the function of antitumor immune cells and imparts chemotherapy resistance. Additionally, recent seminal studies have demonstrated crucial roles for metabolic crosstalk - the exchange of metabolites between PDAC cells and stromal cell populations in the TME - in establishing and maintaining core malignant behaviors of PDAC: tumor growth, metastasis, immune evasion, and therapy resistance. In this review, we provide a conceptual overview of metabolic crosstalk and how it evolves under various selection pressures in the TME, analyze the landscape of proposed tumorigenic metabolic crosstalk pathways, and highlight potentially druggable nodes.

Lactate-mediated metabolic reprogramming of tumor-associated macrophages: implications for tumor progression and therapeutic potential

The tumor microenvironment (TME) is characterized by distinct metabolic adaptations that not only drive tumor progression but also profoundly influence immune responses. Among these adaptations, lactate, a key metabolic byproduct of aerobic glycolysis, accumulates in the TME and plays a pivotal role in regulating cellular metabolism and immune cell function. Tumor-associated macrophages (TAMs), known for their remarkable functional plasticity, serve as critical regulators of the immune microenvironment and tumor progression. Lactate modulates TAM polarization by influencing the M1/M2 phenotypic balance through diverse signaling pathways, while simultaneously driving metabolic reprogramming. Furthermore, lactate-mediated histone and protein lactylation reshapes TAM gene expression, reinforcing their immunosuppressive properties. From a therapeutic perspective, targeting lactate metabolism has shown promise in reprogramming TAMs and enhancing anti-tumor immunity. Combining these metabolic interventions with immunotherapies may further augment treatment efficacy. This review underscores the crucial role of lactate in TAM regulation and tumor progression, highlighting its potential as a promising therapeutic target in cancer treatment.

A basigin antibody modulates MCTs to impact tumor metabolism and immunity

Lactate metabolism and signaling intricately intertwine in the context of cancer and immunity. Basigin, working alongside monocarboxylate transporters MCT1 and MCT4, orchestrates the movement of lactate across cell membranes. Despite their potential in treating formidable tumors, the mechanisms by which basigin antibodies affect basigin and MCTs remain unclear. Our research demonstrated that basigin positively modulates MCT activity. We subsequently developed a basigin antibody that converts basigin into a negative modulator, thereby suppressing lactate transport and enhancing anti-tumor immunity. Additionally, the antibody alters metabolic profiles in NSCLC-PDOs and T cells. Cryo-EM structural analysis and molecular dynamics simulations reveal that the extracellular Ig2 domain and transmembrane domain of basigin regulate MCT1 activity through an allosteric mechanism. The antibody decreases MCT1 transition rate by reducing the flexibility of basigin's Ig2 domain and diminishing interactions between basigin's transmembrane domain and MCT1. These findings underscore the promise of basigin antibodies in combating tumors by modulating metabolism and immunity, and the value of a common therapeutic subunit shared by multiple transporter targets.

SLC4A7 suppresses lung adenocarcinoma oncogenesis by reducing lactate transport and protein lactylation

Lactate and protein lactylation serve a key role in tumor pathogenesis. Solute carrier 4A7 (SLC4A7), a key transporter, participates in cellular acid homeostasis. However, its impact on lactate transport and protein lactylation in solid tumors, particularly lung adenocarcinoma (LUAD), remains largely unexplored. In the present study, lactylome analysis, Transwell and wound healing assay, animal experiments were conducted to validate functional regulation mediated by SLC4A7 in LUAD. SLC4A7 inhibited tumor progression, including metastasis, invasion and proliferation. Mechanistically, SLC4A7 decreased both intracellular and extracellular lactate accumulation and inhibited overall protein lactylation, as confirmed by lactylome analysis. Analyzing the lactylome revealed that SLC4A7 suppressed lysine lactylation of numerous genes like HSP90AA1 and pathways such as focal adhesion associated with carcinogenesis. Additionally, low expression levels of SLC4A7 in LUAD cancer stem cells were validated using tumor tissue samples from patients with LUAD. Moreover, the inhibitory role of SLC4A7 in regulating tumor stemness was verified. Collectively, the present results uncovered the inhibitory effect exerted by SLC4A7 on tumor progression via its regulation of lactate transport, protein lactylation and stemness properties. Targeting SLC4A7 may hold promise as a novel therapeutic strategy for LUAD.

Lactylation in cancer progression and drug resistance

Lactate plays a crucial role as an energy substrate, metabolite, and signaling molecule in cancer. Lactate has long been considered a byproduct of glycolysis. Still, the lactate shuttle hypothesis has changed the lactate paradigm, revealing the implications of lactate in cellular metabolism and cellular communications that can transcend the compartment barrier and occur within and between different cells, tissues, and organs. Due to the Warburg effect, the tumor produces a large amount of lactate, thus creating a low-nutrition, hypoxic, and low-pH tumor microenvironment (TME). Consequently, immunosuppressive networks are built to acquire immune evasion potential and regulate tumor growth. Lactylation is a newly discovered post-translational modification of lysine residues with the capacity for transcriptional regulation via histone modification and modulation of non-histone protein functions, which links gene regulation to cellular metabolism by aberrant metabolism activity and epigenetic modification. There is growing evidence that lactylation plays a crucial role in cancer progression and drug resistance. Targeting lactylation enzymes or metabolic pathways has shown promising effects in suppressing cancer progression and drug resistance, highlighting the therapeutic potential of this modification. Therefore, in this review, we offer a systematic overview of lactate homeostasis in physiological and pathological processes as well as discuss the influence of lactylation in cancer progression and drug resistance and underlying molecular mechanisms, providing a theoretical basis for further research.

Metformin as an immunomodulatory agent in enhancing head and neck squamous cell carcinoma therapies

Head and neck squamous cell carcinoma (HNSCC) remains a significant clinical challenge due to its aggressive behavior and poor prognosis, making the development of novel therapeutics with enhanced efficacy and minimal side effects critical. Metformin, a widely used antidiabetic agent, has recently emerged as a potential adjunctive therapy for HNSCC, exhibiting both direct anti-tumor and immunomodulatory effects. This review comprehensively explores the multifaceted role of metformin in shaping the tumor immune microenvironment within HNSCC. We emphasize its pivotal role in modulating immune cell populations and its potential for synergistic action with immunotherapeutic strategies. Furthermore, we address the current challenges associated with optimizing dosing regimens, identifying predictive biomarkers, and integrating metformin with immunotherapy. By dissecting these aspects, this review aims to pave the way for the development of personalized HNSCC treatment strategies that fully exploit the therapeutic potential of metformin.

Impact of lactate on immune cell function in the tumor microenvironment: mechanisms and therapeutic perspectives

Lactate has emerged as a key regulator in the tumor microenvironment (TME), influencing both tumor progression and immune dynamics. As a byproduct of aerobic glycolysis, lactate satisfies the metabolic needs of proliferating tumor cells while reshaping the TME to facilitate immune evasion. Elevated lactate levels inhibit effector immune cells such as CD8+ T and natural killer cells, while supporting immunosuppressive cells, such as regulatory T cells and myeloid-derived suppressor cells, thus fostering an immunosuppressive environment. Lactate promotes epigenetic reprogramming, stabilizes hypoxia-inducible factor-1α, and activates nuclear factor kappa B, leading to further immunological dysfunction. In this review, we examined the role of lactate in metabolic reprogramming, immune suppression, and treatment resistance. We also discuss promising therapeutic strategies targeting lactate metabolism, including lactate dehydrogenase inhibitors, monocarboxylate transporter inhibitors, and TME neutralization methods, all of which can restore immune function and enhance immunotherapy outcomes. By highlighting recent advances, this review provides a theoretical foundation for integrating lactate-targeted therapies into clinical practice. We also highlight the potential synergy between these therapies and current immunotherapeutic strategies, providing new avenues for addressing TME-related challenges and improving outcomes for patients with cancer.

The Role of Lactate and Lactylation in the Dysregulation of Immune Responses in Psoriasis

Historically, lactate has been considered merely a metabolic byproduct. However, recent studies have revealed that lactate plays a much more dynamic role, acting as an immune signaling molecule that influences cellular communication, through the process of "lactate shuttling." Lactylation, a novel post-translational modification, is directly derived from lactate and represents an emerging mechanism through which lactate exerts its effects on cellular function. It has been shown to directly affect immune cells by modulating the activation of pro-inflammatory and anti-inflammatory pathways. This modification influences the expression of key immune-related genes, thereby impacting immune cell differentiation, cytokine production, and overall immune response. In this review, we focused on the role of lactate and lactylation in the dysregulation of immune responses in psoriasis and its relapse. Additionally, we discuss the potential applications of targeting lactate metabolism and lactylation modifications in the treatment of psoriasis, alongside the investigation of artificial intelligence applications in advancing lactate and lactylation-focused drug development, identifying therapeutic targets, and enabling personalized medical decision-making. The significance of this review lies in its comprehensive exploration of how lactate and lactylation contribute to immune dysregulation, offering a novel perspective for understanding the metabolic and epigenetic changes associated with psoriasis. By identifying the roles of these pathways in modulating immune responses, this review provides a foundation for the development of new therapeutic strategies that target these mechanisms.

Lactate: A key regulator of the immune response

Lactate, the end product of both anaerobic and aerobic glycolysis in proliferating and growing cells-with the latter process known as the Warburg effect-is historically considered a mere waste product of cell and tissue metabolism. However, research over the past ten years has unveiled multifaceted functions of lactate that critically shape and impact cellular biology. Beyond serving as a fuel source, lactate is now known to influence gene expression through histone modification and to function as a signaling molecule that impacts a wide range of cellular activities. These properties have been particularly studied in the context of both adaptive and innate immune responses. Here, we review the diverse roles of lactate in the regulation of the immune system during homeostasis and disease pathogenesis (including cancer, infection, cardiovascular diseases, and autoimmunity). Furthermore, we describe recently proposed therapeutic interventions for manipulating lactate metabolism in human diseases.

Elevated Lactate in the AML Bone Marrow Microenvironment Polarizes Leukemia-Associated Macrophages via GPR81 Signaling

Interactions between acute myeloid leukemia (AML) and the bone marrow microenvironment (BMME) are critical to leukemia progression and chemoresistance. In the solid tumor microenvironment, altered metabolite levels contribute to cancer progression. We performed a metabolomic analysis of AML patient bone marrow serum, revealing increased metabolites compared to age- and sex-matched controls. The most highly elevated metabolite in the AML BMME was lactate. Lactate signaling in solid tumors induces immunosuppressive tumor-associated macrophages and correlates with poor prognosis. This has not yet been studied in the leukemic BMME. Herein, we describe the role of lactate in the polarization of leukemia-associated macrophages (LAMs). Using a murine AML model of blast crisis chronic myelogenous leukemia (bcCML), we characterize the suppressive phenotype of LAMs by surface markers, transcriptomics, and cytokine profiling. Then, mice genetically lacking GPR81, the extracellular lactate receptor, were used to demonstrate GPR81 signaling as a mechanism of both the polarization of LAMs and the direct support of leukemia cells. Furthermore, elevated lactate diminished the function of hematopoietic progenitors and reduced stromal support for normal hematopoiesis. We report microenvironmental lactate as a mechanism of AML-induced immunosuppression and leukemic progression, thus identifying GPR81 signaling as an exciting and novel therapeutic target for treating this devastating disease.

Mitochondrial-uncoupling nanomedicine for self-heating and immunometabolism regulation in cancer cells

Developing endogenous hyperthermia offers a promising strategy to address challenges with current exogenous hyperthermia techniques in clinics. Herein, a CD44-targeted and thermal-responsive nanocarrier was developed for the simultaneous delivery of 2,4-dinitrophenol and syrosingopine. The objective was to induce endogenous hyperthermia and regulate immunometabolism, ultimately augmenting anti-tumour immune responses. Dinitrophenol as mitochondrial uncoupler can convert electrochemical potential energy of inner mitochondrial membrane into heat, facilitating endogenous hyperthermia. Meanwhile, syrosingopine not only inhibits excessive lactate efflux caused by dinitrophenol but also downregulates tumour cell glycolysis, thus alleviating immunosuppression and heat shock protein (HSP)-dependent thermo-resistance through immunometabolism regulation. The synergistic effects of endogenous hyperthermia and immunometabolism regulation by this nanomedicine have potential to enhance tumor immunogenicity, reshape the tumour immune microenvironment, and effectively suppress the growth of subcutaneous tumours and patient-derived organoids in triple-negative breast cancer. Therefore, the endogenous hyperthermia strategy developed in this study would revolutionize hyperthermia for cancer treatment.

Emerging Roles of Nanozyme in Tumor Metabolism Regulation: Mechanisms, Applications, and Future Directions

Nanozymes, nanomaterials with intrinsic enzyme activity, have garnered significant attention in recent years due to their catalytic abilities comparable to natural enzymes, cost-effectiveness, high catalytic activities, and stability against environmental fluctuations. As functional analogs of natural enzymes, nanozymes participate in various critical metabolic processes, including glucose metabolism, lactate metabolism, and the maintenance of redox homeostasis, all of which are essential for normal cellular functions. However, disruptions in these metabolic pathways frequently promote tumorigenesis and progression, making them potential therapeutic targets. While several therapies targeting tumor metabolism are currently in clinical or preclinical stages, their efficacy requires further enhancement. Consequently, nanozymes that target tumor metabolism are regarded as a promising therapeutic strategy. Despite extensive studies investigating the application of nanozymes in tumor metabolism, relevant reviews are relatively scarce. This article first introduces the physicochemical properties and biological behaviors of nanozymes. Subsequently, we analyze the role of nanozymes in tumor metabolism and explore their potential applications in tumor therapy. In conclusion, this review aims to foster innovative research in related fields and advance the development of nanozyme-based strategies for cancer diagnostics and therapeutics.

Energy metabolism in health and diseases

Energy metabolism is indispensable for sustaining physiological functions in living organisms and assumes a pivotal role across physiological and pathological conditions. This review provides an extensive overview of advancements in energy metabolism research, elucidating critical pathways such as glycolysis, oxidative phosphorylation, fatty acid metabolism, and amino acid metabolism, along with their intricate regulatory mechanisms. The homeostatic balance of these processes is crucial; however, in pathological states such as neurodegenerative diseases, autoimmune disorders, and cancer, extensive metabolic reprogramming occurs, resulting in impaired glucose metabolism and mitochondrial dysfunction, which accelerate disease progression. Recent investigations into key regulatory pathways, including mechanistic target of rapamycin, sirtuins, and adenosine monophosphate-activated protein kinase, have considerably deepened our understanding of metabolic dysregulation and opened new avenues for therapeutic innovation. Emerging technologies, such as fluorescent probes, nano-biomaterials, and metabolomic analyses, promise substantial improvements in diagnostic precision. This review critically examines recent advancements and ongoing challenges in metabolism research, emphasizing its potential for precision diagnostics and personalized therapeutic interventions. Future studies should prioritize unraveling the regulatory mechanisms of energy metabolism and the dynamics of intercellular energy interactions. Integrating cutting-edge gene-editing technologies and multi-omics approaches, the development of multi-target pharmaceuticals in synergy with existing therapies such as immunotherapy and dietary interventions could enhance therapeutic efficacy. Personalized metabolic analysis is indispensable for crafting tailored treatment protocols, ultimately providing more accurate medical solutions for patients. This review aims to deepen the understanding and improve the application of energy metabolism to drive innovative diagnostic and therapeutic strategies.

Lactate metabolism in clonal plasma cells and its therapeutic implications in multiple myeloma patients with elevated serum LDH levels

INTRODUCTION

This study aimed to evaluate the metabolic differences between MM cells derived from patients with elevated serum LDH levels and those without elevated serum LDH levels to identify biological differences that could be exploited for therapeutic purposes.

METHODS

We performed transcriptome assessments of CD138 + MM cells derived from patients with elevated serum LDH levels compared to those without elevated serum LDH levels and validated the findings in a larger public dataset. Functional metabolic assessments of our findings were performed using a combination of stable isotope resolved metabolomics (SIRM), bioenergetic flux measurement assays, and live cell analysis in human myeloma cell lines and primary MM patient cells.

RESULTS

We identified SLC16A1, responsible for the formation of MCT1, a well-defined bi-directional transporter of lactate in and out of a cell with a predilection to importing extracellular lactate, as differentially expressed between the two groups. This finding was functionally confirmed by higher membranous MCT1 protein expression and SIRM on MM cells derived from patients with elevated serum LDH levels compared to those without elevated serum LDH levels. Finally, disrupting lactate transport in and out of CD138 + MM cells was maximally achievable only with dual inhibition of MCT1 and its partner, MCT4, which was preferentially more cytotoxic in MM cells derived from patients with elevated serum levels of LDH.

CONCLUSION

MCT1 mRNA and protein expression distinguish MM cells derived from patients with elevated serum LDH levels from those without elevated serum LDH levels. However, only dual inhibition of MCT1 and MCT4 can disrupt lactate transport in multiple myeloma (MM) cells, with preferential cytotoxicity in MM cells from patients with high serum LDH levels.

Integrative Analysis of Metabolome and Proteome in the Cerebrospinal Fluid of Patients with Multiple System Atrophy

Multiple system atrophy (MSA) is a progressive neurodegenerative synucleinopathy. Differentiating MSA from other synucleinopathies, especially in the early stages, is challenging because of its overlapping symptoms with other forms of Parkinsonism. Thus, there is a pressing need to clarify the underlying biological mechanisms and identify specific biomarkers for MSA. The metabolic profile of cerebrospinal fluid (CSF) is known to be altered in MSA. To further investigate the biological mechanisms behind the metabolic changes, we created a network of altered CSF metabolites in patients with MSA and analysed these changes using bioinformatic software. Acknowledging the limitations of metabolomics, we incorporated proteomic data to improve the overall comprehensiveness of the study. Our in silico predictions showed elevated ROS, cytoplasmic inclusions, white matter demyelination, ataxia, and neurodegeneration, with ATP concentration, neurotransmitter release, and oligodendrocyte count predicted to be suppressed in MSA CSF samples. Machine learning and dimension reduction are important multi-omics approaches as they handle large amounts of data, identify patterns, and make predictions while reducing variance without information loss and generating easily visualised plots that help identify clusters, patterns, or outliers. Thus, integrated multiomics and machine learning approaches are essential for elucidating neurodegenerative mechanisms and identifying potential diagnostic biomarkers of MSA.

Lactate and lactylation in cancer

Accumulated evidence has implicated the diverse and substantial influence of lactate on cellular differentiation and fate regulation in physiological and pathological settings, particularly in intricate conditions such as cancer. Specifically, lactate has been demonstrated to be pivotal in molding the tumor microenvironment (TME) through its effects on different cell populations. Within tumor cells, lactate impacts cell signaling pathways, augments the lactate shuttle process, boosts resistance to oxidative stress, and contributes to lactylation. In various cellular populations, the interplay between lactate and immune cells governs processes such as cell differentiation, immune response, immune surveillance, and treatment effectiveness. Furthermore, communication between lactate and stromal/endothelial cells supports basal membrane (BM) remodeling, epithelial-mesenchymal transitions (EMT), metabolic reprogramming, angiogenesis, and drug resistance. Focusing on lactate production and transport, specifically through lactate dehydrogenase (LDH) and monocarboxylate transporters (MCT), has shown promise in the treatment of cancer. Inhibitors targeting LDH and MCT act as both tumor suppressors and enhancers of immunotherapy, leading to a synergistic therapeutic effect when combined with immunotherapy. The review underscores the importance of lactate in tumor progression and provides valuable perspectives on potential therapeutic approaches that target the vulnerability of lactate metabolism, highlighting the Heel of Achilles for cancer treatment.

Focal adhesion kinase promotes aerobic glycolysis in hepatic stellate cells via the cyclin D1/c-Myc/MCT-1 pathway to induce liver fibrosis

Hepatic stellate cells (HSCs) transdifferentiate into myofibroblasts during liver fibrosis and exhibit increased glycolysis. Phosphorylated focal adhesion kinase (FAK) (pY397-FAK) promotes monocarboxylate transporter 1 (MCT-1) expression in HSCs to increase aerobic glycolysis and cause liver fibrosis. A combined multiomics analysis of C57BL/6 mice with tetrachloromethane (CCl4)-induced liver fibrosis was performed to identify the downstream FAK signaling pathway. The effect of the FAK inhibitor PF562271 on CCl4-induced liver fibrosis was explored by immunofluorescence of liver tissues. The migration, proliferation and aerobic glycolysis of LX-2 cells after stimulation and activation by transforming growth factor beta-1 (TGF-β1) or suppression by PF562271 was assessed in vitro. Multiomics analysis of a successfully generated CCl4-induced liver fibrosis mouse model was performed. FAK and cyclin D1 were significantly enriched in mice with CCl4-induced liver fibrosis. In vivo, the MCT-1 and alpha smooth muscle actin (α-SMA) levels were increased in mice with CCl4-induced liver fibrosis, and MCT-1 and α-SMA expression decreased after PF562271 treatment. In vitro, PF562271 alleviated TGF-β1-induced LX-2 activation. LX-2 cells showed diminished migration, proliferation, and aerobic glycolysis after PF562271 intervention. FAK promotes aerobic glycolysis in LX-2 cells through the cyclin D1/c-Myc/MCT-1 pathway, thereby increasing liver fibrosis.

Lactate-induced protein lactylation in cancer: functions, biomarkers and immunotherapy strategies

Lactate, long viewed as a byproduct of glycolysis and metabolic waste. Initially identified within the context of yogurt fermentation, lactate's role extends beyond culinary applications to its significance in biochemical processes. Contemporary research reveals that lactate functions not merely as the terminal product of glycolysis but also as a nexus for initiating physiological and pathological responses within the body. Lysine lactylation (Kla), a novel post-translational modification (PTM) of proteins, has emerged as a pivotal mechanism by which lactate exerts its regulatory influence. This epigenetic modification has the potential to alter gene expression patterns, thereby impacting physiological and pathological processes. Increasing evidence indicates a correlation between lactylation and adverse prognosis in various malignancies. Consequently, this review article aims to encapsulate the proteins that interact with lactate, elucidate the role of lactylation in tumorigenesis and progression, and explore the potential therapeutic targets afforded by the modulation of lactylation. The objective of this review is to clarify the oncogenic significance of lactylation and to provide a strategic framework for future research directions in this burgeoning field.

The impact of solute carrier proteins on disrupting substance regulation in metabolic disorders: insights and clinical applications

Carbohydrates, lipids, bile acids, various inorganic salt ions and organic acids are the main nutrients or indispensable components of the human body. Dysregulation in the processes of absorption, transport, metabolism, and excretion of these metabolites can lead to the onset of severe metabolic disorders, such as type 2 diabetes, non-alcoholic fatty liver disease, gout and hyperbilirubinemia. As the second largest membrane receptor supergroup, several major families in the solute carrier (SLC) supergroup have been found to play key roles in the transport of substances such as carbohydrates, lipids, urate, bile acids, monocarboxylates and zinc ions. Based on common metabolic dysregulation and related metabolic substances, we explored the relationship between several major families of SLC supergroup and metabolic diseases, providing examples of drugs targeting SLC proteins that have been approved or are currently in clinical/preclinical research as well as SLC-related diagnostic techniques that are in clinical use or under investigation. By highlighting these connections, we aim to provide insights that may contribute to the development of improved treatment strategies and targeted therapies for metabolic disorders.

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.

Reference-Attached pH Nanosensor for Accurately Monitoring the Rapid Kinetics of Intracellular H+ Oscillations

Intracellular pH (pHi) is an essential indicator of cellular metabolic activity, as its transient or small shift can significantly impact cellular homeostasis and reflect the cellular events. Real-time and precise tracking of these rapid pH changes within a single living cell is therefore important. However, achieving high dynamic response performance (subsecond) pH detection inside a living cell with high accuracy remains a challenge. Here a reference-attached pH nanosensor (R-pH-nanosensor) with fast and precise pHi sensing performance is introduced. The nanosensor comprises a highly conductive H+-sensitive IrRuOx nanowire (SiC@IrRuOx NW) as the intracellular working electrode and a SiC@Ag/AgCl NW as an intracellular reference electrode (RE) to diminish the interferences arising from cell membrane potential fluctuations. This whole-inside-cell detection mode ensures that the entire potential detection circuit is located within the same cell, and the R-pH-nanosensor is able to quantify the mild acidification of cytosol and completely record the fast pH variation within a single cell. It also enables real-time potentiometric monitoring of the pHi oscillations, which synchronize with the glycolysis oscillations in cancer cells. Furthermore, the asymmetry in glycolysis oscillations wave is disclosed and the inhibitory effect of just lactate to glycolysis oscillations is further confirmed.

Collateral lethality: A unique type of synthetic lethality in cancers

Genetic interactions play crucial roles in cell-essential functions. Intrinsic genetic defects in tumors typically involve gain-of- and loss-of-function mutations in tumor suppressor genes (TSGs) and oncogenes, respectively, providing potential antitumor vulnerabilities. Moreover, tumor cells with TSG deficiencies exhibit heightened sensitivity to the inhibition of compensatory pathways. Synthetic and collateral lethality are two strategies used for exploiting novel drug targets in multiple types of cancer. Collateral lethality is a unique type of synthetic lethality that occurs when passenger genes are co-deleted in neighboring TSGs. Although synthetic lethality has already been successfully demonstrated in clinical practice, antitumor therapeutics based on collateral lethality are predominantly still in the preclinical phase. Therefore, screening for potential genetic interactions within the cancer genome has emerged as a promising approach for drug development. Here, the two conceptual therapeutic strategies that involve the deletion or inactivation of cancer-specific TSGs are discussed. Moreover, existing approaches for screening and identifying potential gene partners are also discussed. Particularly, this review highlights the current advances of "collateral lethality" in the preclinical phase and addresses the challenges involved in translating them into therapeutic applications. This review provides insights into these strategies as new opportunities for the development of personalized antitumor therapies.

Postischemic inactivation of HIF prolyl hydroxylases in endothelium promotes maladaptive kidney repair by inducing glycolysis

Ischemic acute kidney injury (AKI) is common in hospitalized patients and increases the risk for chronic kidney disease (CKD). Impaired endothelial cell (EC) functions are thought to contribute in AKI to CKD transition, but the underlying mechanisms remain unclear. Here, we identify a critical role for endothelial oxygen sensing prolyl hydroxylase domain (PHD) enzymes 1-3 in regulating postischemic kidney repair. In renal endothelium, we observed compartment-specific differences in the expression of the 3 PHD isoforms in both mice and humans. Postischemic concurrent inactivation of endothelial PHD1, PHD2, and PHD3 but not PHD2 alone promoted maladaptive kidney repair characterized by exacerbated tissue injury, fibrosis, and inflammation. scRNA-Seq analysis of the postischemic endothelial PHD1, PHD2, and PHD3-deficient (PHDTiEC) kidney revealed an endothelial hypoxia and glycolysis-related gene signature, also observed in human kidneys with severe AKI. This metabolic program was coupled to upregulation of the SLC16A3 gene encoding the lactate exporter monocarboxylate transporter 4 (MCT4). Strikingly, treatment with the MCT4 inhibitor syrosingopine restored adaptive kidney repair in PHDTiEC mice. Mechanistically, MCT4 inhibition suppressed proinflammatory EC activation, reducing monocyte-EC interaction. Our findings suggest avenues for halting AKI to CKD transition based on selectively targeting the endothelial hypoxia-driven glycolysis/MCT4 axis.

Progress in Lactate Metabolism and Its Regulation via Small Molecule Drugs

Lactate, once viewed as a byproduct of glycolysis and a metabolic "waste", is now recognized as an energy-providing substrate and a signaling molecule that modulates cellular functions under pathological conditions. The discovery of histone lactylation in 2019 marked a paradigm shift, with subsequent studies revealing that lactate can undergo lactylation with both histone and non-histone proteins, implicating it in the pathogenesis of various diseases, including cancer, liver fibrosis, sepsis, ischemic stroke, and acute kidney injury. Aberrant lactate metabolism is associated with disease onset, and its levels can predict disease outcomes. Targeting lactate production, transport, and lactylation may offer therapeutic potential for multiple diseases, yet a systematic summary of the small molecules modulating lactate and its metabolism in various diseases is lacking. This review outlines the sources and clearance of lactate, as well as its roles in cancer, liver fibrosis, sepsis, ischemic stroke, myocardial infarction, and acute kidney injury, and summarizes the effects of small molecules on lactate regulation. It aims to provide a reference and direction for future research.

Lactate metabolism and lactylation in cardiovascular disease: novel mechanisms and therapeutic targets

Cardiovascular disease (CVD) is responsible for approximately 30% of annual global mortality rates, yet existing treatments for this condition are considered less than ideal. Despite being previously overlooked, lactate, a byproduct of glycolysis, is now acknowledged for its crucial role in the cellular functions of the cardiovascular system. Recent studies have shown that lactate influences the proliferation, differentiation, and activation of immune cells through its modulation of post-translational protein modifications, thereby affecting the development and prognosis of cardiovascular disease. Consequently, there has been a notable increase in interest towards drug targets targeting lactylation in immune cells, prompting further exploration. In light of the swift advancements in this domain, this review article is dedicated to examining lactylation in cardiovascular disease and potential drug targets for regulating lactylation, with the aim of enhancing comprehension of this intricate field.

Lactate: a rising star in tumors and inflammation

Lactate has been traditionally regarded as a mere byproduct of glycolysis or metabolic waste. However, an increasing body of literature suggests its critical role in regulating various physiological and pathological processes. Lactate is generally associated with hypoxia, inflammation, viral infections, and tumors. It performs complex physiological roles by activating monocarboxylate transporter (MCT) or the G protein-coupled receptor GPR81 across the cell membrane. Lactate exerts immunosuppressive effects by regulating the functions of various immune cells (such as natural killer cells, T cells, dendritic cells, and monocytes) and its role in macrophage polarization and myeloid-derived suppressor cell (MDSC) differentiation in the tumor microenvironment. Lactic acid has also recently been found to increase the density of CD8+ T cells, thereby enhancing the antitumor immune response. Acute or chronic inflammatory diseases have opposite immune states in the inflammatory disease microenvironment. Factors such as cell types, transcriptional regulators, ionic mediators, and the microenvironment all contribute to the diverse functions lactate exhibits. Herein, we reviewed the pleiotropic effects of lactate on the regulation of various functions of immune cells in the tumor microenvironment and under inflammatory conditions, which may help to provide new insights and potential targets for the diagnosis and treatment of inflammatory diseases and malignancies.

Daily oral administration of probiotics engineered to constantly secrete short-chain fatty acids effectively prevents myocardial injury from subsequent ischaemic heart disease

AIMS

Given the extremely limited regeneration potential of the heart, one of the most effective strategies to reduce the prevalence and mortality of coronary artery disease is prevention. Short-chain fatty acids (SCFAs), which are by-products of beneficial probiotics, have been reported to possess cardioprotective effects. Despite their beneficial roles, delivering SCFAs and maintaining their effective concentration in plasma present major challenges. Therefore, in the present study, we aimed to devise a strategy to prevent coronary heart disease effectively by using engineered probiotics to continuously release SCFAs in vivo.

METHODS AND RESULTS

We engineered a novel probiotic cocktail, namely EcN_TL, from the commercially available Escherichia coli Nissle 1917 (EcN) strain to continuously secrete SCFAs by introducing the propionate and butyrate biosynthetic pathways. Oral administration of EcN_TL enhanced and maintained an effective concentration of SCFAs in the plasma. As a preventative strategy, we observed that daily intake of EcN_TL for 14 days prior to ischaemia-reperfusion injury significantly reduced myocardial injury and improved cardiac performance compared with EcN administration. We uncovered that EcN_TL's protective mechanisms included reducing neutrophil infiltration into the infarct site and promoting the polarization of wound healing macrophages. We further revealed that SCFAs at plasma concentration protected cardiomyocytes from inflammation by suppressing the NF-κB activation pathway.

CONCLUSION

These data provide strong evidence to support the use of SCFA-secreting probiotics to prevent coronary heart disease. Since SCFAs also play a key role in other metabolic diseases, EcN_TL can potentially be used to treat a variety of other diseases.

Inducing disulfidptosis in tumors:potential pathways and significance

Regulated cell death (RCD) is crucial for the elimination of abnormal cells. In recent years, strategies aimed at inducing RCD, particularly apoptosis, have become increasingly important in cancer therapy. However, the ability of tumor cells to evade apoptosis has led to treatment resistance and relapse, prompting extensive research into alternative death processes in cancer cells. A recent study identified a novel form of RCD known as disulfidptosis, which is linked to disulfide stress. Cancer cells import cystine from the extracellular environment via solute carrier family 7 member 11 (SLC7A11) and convert it to cysteine using nicotinamide adenine dinucleotide phosphate (NADPH). When NADPH is deficient or its utilization is impaired, cystine accumulates, leading to the formation of disulfide bonds in the actin cytoskeleton, triggering disulfidptosis. Disulfidptosis reveals a metabolic vulnerability in tumors, offering new insights into cancer therapy strategies. This review provides a detailed overview of the mechanisms underlying disulfidptosis, the current research progress, and limitations. It also highlights innovative strategies for inducing disulfidptosis and explores the potential of combining these approaches with traditional cancer therapies, particularly immunotherapy, to expedite clinical translation.

Deregulation of lactate permeability using a small-molecule transporter (Lactrans-1) disturbs intracellular pH and triggers cancer cell death

Due to the relevance of lactic acidosis in cancer, several therapeutic strategies have been developed targeting its production and/or regulation. In this matter, inhibition approaches of key proteins such as lactate dehydrogenase or monocarboxylate transporters have showed promising results, however, metabolic plasticity and tumor heterogeneity limits their efficacy. In this study, we explored the anticancer potential of a new strategy based on disturbing lactate permeability independently of monocarboxylate transporters activity using a small molecule ionophore named Lactrans-1. Derived from click-tambjamines, Lactrans-1 facilitates transmembrane lactate transportation in liposome models and reduces cancer cell viability. The results showed that Lactrans-1 triggered both apoptosis and necrosis depending on the cell line tested, displaying a synergistic effect in combination with first-line standard chemotherapeutic cisplatin. The ability of this compound to transport outward lactate anions was confirmed in A549 and HeLa cells, two cancer cell lines having distinct rates of lactate production. In addition, through cell viability reversion experiments it was possible to establish a correlation between the amount of lactate transported and the cytotoxic effect exhibited. The movement of lactate anions was accompanied with intracellular pH disturbances that included basification of lysosomes and acidification of the cytosol and mitochondria. We also observed mitochondrial swelling, increased ROS production and activation of oxidative stress signaling pathways p38-MAPK and JNK/SAPK. Our findings provide evidence that enhancement of lactate permeability is critical for cellular pH homeostasis and effective to trigger cancer cell death, suggesting that Lactrans-1 may be a promising anticancer therapy.

Beyond Cancer Cells: How the Tumor Microenvironment Drives Cancer Progression

Liver cancer represents a substantial global health challenge, contributing significantly to worldwide morbidity and mortality. It has long been understood that tumors are not composed solely of cancerous cells, but also include a variety of normal cells within their structure. These tumor-associated normal cells encompass vascular endothelial cells, fibroblasts, and various inflammatory cells, including neutrophils, monocytes, macrophages, mast cells, eosinophils, and lymphocytes. Additionally, tumor cells engage in complex interactions with stromal cells and elements of the extracellular matrix (ECM). Initially, the components of what is now known as the tumor microenvironment (TME) were thought to be passive bystanders in the processes of tumor proliferation and local invasion. However, recent research has significantly advanced our understanding of the TME's active role in tumor growth and metastasis. Tumor progression is now known to be driven by an intricate imbalance of positive and negative regulatory signals, primarily influenced by specific growth factors produced by both inflammatory and neoplastic cells. This review article explores the latest developments and future directions in understanding how the TME modulates liver cancer, with the aim of informing the design of novel therapies that target critical components of the TME.

Enhanced glycolysis causes extracellular acidification and activates acid-sensing ion channel 1a in hypoxic pulmonary hypertension

In pulmonary hypertension (PHTN), a metabolic shift to aerobic glycolysis promotes a hyperproliferative, apoptosis-resistant phenotype in pulmonary arterial smooth muscle cells (PASMCs). Enhanced glycolysis induces extracellular acidosis, which can activate proton-sensing membrane receptors and ion channels. We previously reported that activation of the proton-gated cation channel acid-sensing ion channel 1a (ASIC1a) contributes to the development of hypoxic PHTN. Therefore, we hypothesize that enhanced glycolysis and subsequent acidification of the PASMC extracellular microenvironment activate ASIC1a in hypoxic PHTN. We observed decreased oxygen consumption rate and increased extracellular acidification rate in PASMCs from chronic hypoxia (CH)-induced PHTN rats, indicating a shift to aerobic glycolysis. In addition, we found that intracellular alkalization and extracellular acidification occur in PASMCs following CH and in vitro hypoxia, which were prevented by the inhibition of glycolysis with 2-deoxy-d-glucose (2-DG). Inhibiting H+ transport/secretion through carbonic anhydrases, Na+/H+ exchanger 1, or vacuolar-type H+-ATPase did not prevent this pH shift following hypoxia. Although the putative monocarboxylate transporter 1 (MCT1) and -4 (MCT4) inhibitor syrosingopine prevented the pH shift, the specific MCT1 inhibitor AZD3965 and/or the MCT4 inhibitor VB124 were without effect, suggesting that syrosingopine targets the glycolytic pathway independent of H+ export. Furthermore, 2-DG and syrosingopine prevented enhanced ASIC1a-mediated store-operated Ca2+ entry in PASMCs from CH rats. These data suggest that multiple H+ transport mechanisms contribute to extracellular acidosis and that inhibiting glycolysis-rather than specific H+ transporters-more effectively prevents extracellular acidification and ASIC1a activation. Together, these data reveal a novel pathological relationship between glycolysis and ASIC1a activation in hypoxic PHTN.NEW & NOTEWORTHY In pulmonary hypertension, a metabolic shift to aerobic glycolysis drives a hyperproliferative, apoptosis-resistant phenotype in pulmonary arterial smooth muscle cells. We demonstrate that this enhanced glycolysis induces extracellular acidosis and activates the proton-gated ion channel, acid-sensing ion channel 1a (ASIC1a). Although multiple H+ transport/secretion mechanisms are upregulated in PHTN and likely contribute to extracellular acidosis, inhibiting glycolysis with 2-deoxy-d-glucose or syrosingopine effectively prevents extracellular acidification and ASIC1a activation, revealing a promising therapeutic avenue.

The Inhibitory Effects of the Natural Stilbene Piceatannol on Lactate Transport In Vitro Mediated by Monocarboxylate Transporters

SCOPE

Lactate, a signaling molecule and energy source, crosses membranes through monocarboxylate transporters (MCTs). MCT1 and MCT4 are potential cancer drug targets due to their role in metabolic reprogramming of cancer cells. Stilbenes, plant secondary metabolites found in several food sources, have anticancer effects, though their mechanisms of action are not well understood. This study links the anticancer activity of natural stilbenes to tumor cell lactate metabolism.

METHODS AND RESULTS

The impact of resveratrol, pinostilbene, pterostilbene, rhapontigenin, and piceatannol on lactate transport is studied using a fluorescence resonance energy transfer (FRET)-based lactate sensor. The viability and migration of cells expressing MCT1 or MCT4 are also evaluated. Piceatannol inhibits MCT1 effectively at low micromolar concentrations, with less effect on MCT4. All stilbenes significantly reduce cell viability and migration.

CONCLUSIONS

These findings indicate that both MCTs are stilbene targets, with piceatannol highlighted as a cost-effective, low-toxicity compound for studying MCTs in cancer, providing a new mechanism of action of the therapeutic and nutraceutical effects of natural polyphenols. This enriches the understanding of dietary polyphenols in cancer prevention and therapy.

Nanozymes in cancer immunotherapy: metabolic disruption and therapeutic synergy

Over the past decade, there has been a growing emphasis on investigating the role of immunotherapy in cancer treatment. However, it faces challenges such as limited efficacy, a diminished response rate, and serious adverse effects. Nanozymes, a subset of nanomaterials, demonstrate boundless potential in cancer catalytic therapy for their tunable activity, enhanced stability, and cost-effectiveness. By selectively targeting the metabolic vulnerabilities of tumors, they can effectively intensify the destruction of tumor cells and promote the release of antigenic substances, thereby eliciting immune clearance responses and impeding tumor progression. Combined with other therapies, they synergistically enhance the efficacy of immunotherapy. Hence, a large number of metabolism-regulating nanozymes with synergistic immunotherapeutic effects have been developed. This review summarizes recent advancements in cancer immunotherapy facilitated by nanozymes, focusing on engineering nanozymes to potentiate antitumor immune responses by disturbing tumor metabolism and performing synergistic treatment. The challenges and prospects in this field are outlined. We aim to provide guidance for nanozyme-mediated immunotherapy and pave the way for achieving durable tumor eradication.

Isolation of Functional Human MCT Transporters in Saccharomyces cerevisiae

Human monocarboxylate transporters (hMCTs) belong to the solute carrier 16 (SLC16) family of proteins and are responsible for the bi-directional transport of various metabolites, including monocarboxylates, hormones, and aromatic amino acids. Hence, the metabolic role of hMCTs is undisputable, as they are directly involved in providing nutrients for oxidation and gluconeogenesis as well as participate in circulation of iodothyronines. However, due to the difficulty in obtaining suitable amounts of stable hMCT samples, the structural information available for these transporters is limited, hindering the development of effective therapeutics. Here we provide a straightforward, cost-effective strategy for the overproduction of hMCTs using a whole-cell Saccharomyces cerevisiae-based system. Our results indicate that this platform is able to provide three hMCTs, i.e., hMCT1 and hMCT4 (monocarboxylate transporters), and hMCT10 (an aromatic amino acid transporter). hMCT1 and hMCT10 are recovered in the quantity and quality required for downstream structural and functional characterization. Overall, our findings demonstrate the suitability of this platform to deliver physiologically relevant membrane proteins for biophysical studies.

SIRT1 improves lactate homeostasis in the brain to alleviate parkinsonism via deacetylation and inhibition of PKM2

Sirtuin 1 (SIRT1) is a histone deacetylase and plays diverse functions in various physiological events, from development to lifespan regulation. Here, in Parkinson's disease (PD) model mice, we demonstrated that SIRT1 ameliorates parkinsonism, while SIRT1 knockdown further aggravates PD phenotypes. Mechanistically, SIRT1 interacts with and deacetylates pyruvate kinase M2 (PKM2) at K135 and K206, thus leading to reduced PKM2 enzyme activity and lactate production, which eventually results in decreased glial activation in the brain. Administration of lactate in the brain recapitulates PD-like phenotypes. Furthermore, increased expression of PKM2 worsens PD symptoms, and, on the contrary, inhibition of PKM2 by shikonin or PKM2-IN-1 alleviates parkinsonism in mice. Collectively, our data indicate that excessive lactate in the brain might be involved in the progression of PD. By improving lactate homeostasis, SIRT1, together with PKM2, are likely drug targets for developing agents for the treatment of neurodegeneration in PD.

Regulation of macrophage activation by lactylation in lung disease

Lactylation is a process where lactate, a cellular metabolism byproduct, is added to proteins, altering their functions. In the realm of macrophage activation, lactylation impacts inflammatory response and immune regulation. Understanding the effects of lactylation on macrophage activation is vital in lung diseases, as abnormal activation and function are pivotal in conditions like pneumonia, pulmonary fibrosis, COPD, and lung cancer. This review explores the concept of lactylation, its regulation of macrophage activation, and recent research progress in lung diseases. It offers new insights into lung disease pathogenesis and potential therapeutic targets.

Syrosingopine and UK5099 synergistically suppress non-small cell lung cancer by activating the integrated stress response

Non-small cell lung cancer (NSCLC) presents a global health challenge due to its low five-year survival rates, underscoring the need for novel therapeutic strategies. Our research explored the synergistic mechanisms of syrosingopine and UK-5099 in treating NSCLC. In vitro experiments showed that the combination of syrosingopine and UK-5099 significantly synergized to suppress NSCLC proliferation. Further experiments revealed that this combination induced cell cycle arrest and promoted apoptosis in NSCLC cells. In vivo experiments demonstrated that the combination of syrosingopine and UK-5099 markedly inhibited tumor growth. Mechanistic studies revealed that this drug combination promoted mitochondrial damage by inducing lactate accumulation and oxidative stress. Additionally, the combination triggered an integrated stress response (ISR) through the activation of heme-regulated inhibitor kinase (HRI). Importantly, our findings suggested that the synergistic suppression of NSCLC by syrosingopine and UK-5099 was dependent on ISR activation. In summary, our study proposed a promising therapeutic approach that involved the combination of Syrosingopine and UK-5099 to activate ISR, significantly hindering NSCLC growth and proliferation.

Metabolism-Regulating Nanozyme System for Advanced Nanocatalytic Cancer Therapy

Nanocatalytic therapy, an emerging approach in cancer treatment, utilizes nanomaterials to initiate enzyme-mimetic catalytic reactions within tumors, inducing tumor-suppressive effects. However, the targeted and selective catalysis within tumor cells is challenging yet critical for minimizing the adverse effects. The distinctive reliance of tumor cells on glycolysis generates abundant lactate, influencing the tumor's pH, which can be manipulated to selectively activate nanozymatic catalysis. Herein, small interfering ribonucleic acid (siRNA) targeting lactate transporter-mediated efflux is encapsulated within the iron-based metal-organic framework (FeMOF) and specifically delivered to tumor cells through cell membrane coating. This approach traps lactate within the cell, swiftly acidifying the tumor cytoplasm and creating an environment for boosting the catalysis of the FeMOF nanozyme. The nanozyme generates hydroxyl radical (·OH) in the reversed acidic environment, using endogenous hydrogen peroxide (H2O2) produced by mitochondria as a substrate. The induced cytoplasmic acidification disrupts calcium homeostasis, leading to mitochondrial calcium overload, resulting in mitochondrial dysfunction and subsequent tumor cell death. Additionally, the tumor microenvironment is also remodeled, inhibiting migration and invasion, thus preventing metastasis. This groundbreaking strategy combines metabolic regulation with nanozyme catalysis in a toxic drug-free approach for tumor treatment, holding promise for future clinical applications.

Metformin is a potential therapeutic for COVID-19/LUAD by regulating glucose metabolism

Lung adenocarcinoma (LUAD) is the most common and aggressive subtype of lung cancer, and coronavirus disease 2019 (COVID-19) has become a serious public health threat worldwide. Patients with LUAD and COVID-19 have a poor prognosis. Therefore, finding medications that can be used to treat COVID-19/LUAD patients is essential. Bioinformatics analysis was used to identify 20 possible metformin target genes for the treatment of COVID-19/LUAD. PTEN and mTOR may serve as hub target genes of metformin. Metformin may be able to cure COVID-19/LUAD comorbidity through energy metabolism, oxidoreductase NADH activity, FoxO signalling pathway, AMPK signalling system, and mTOR signalling pathway, among other pathways, according to the results of bioinformatic research. Metformin has ability to inhibit the proliferation of A549 cells, according to the results of colony formation and proliferation assays. In A549 cells, metformin increased glucose uptake and lactate generation, while decreasing ATP synthesis and the NAD+/NADH ratio. In summary, PTEN and mTOR may be potential targets of metformin for the treatment of COVID-19/LUAD. The mechanism by which metformin inhibits lung adenocarcinoma cell proliferation may be related to glucose metabolism regulated by PI3K/AKT signalling and mTOR signalling pathways. Our study provides a new theoretical basis for the treatment of COVID-19/LUAD.

Metal-(Acyclic Diaminocarbene) Complexes Demonstrate Nanomolar Antiproliferative Activity against Triple-Negative Breast Cancer

Hydrolytically stable PdII and PtII complexes supported by acyclic diaminocarbene ligands represent a novel class of structural organometallic anticancer agents exhibiting nanomolar antiproliferative activity in a panel of cancer cell lines (IC50 0.07-0.81 μM) and up to 300-fold selectivity for cancer cells over normal primary fibroblasts. The lead drug candidate was 300 times more potent than cisplatin in vitro and showed higher efficacy in reducing the growth of aggressive MDA-MB-231 xenograft tumors in mice.

Lactate in breast cancer cells is associated with evasion of hypoxia-induced cell cycle arrest and adverse patient outcome

Tumor hypoxia is a common microenvironmental factor in breast cancers, resulting in stabilization of Hypoxia-Inducible Factor 1 (HIF-1), the master regulator of hypoxic response in cells. Metabolic adaptation by HIF-1 results in inhibition of citric acid cycle, causing accumulation of lactate in large concentrations in hypoxic cancers. Lactate can therefore serve as a secondary microenvironmental factor influencing cellular response to hypoxia. Presence of lactate can alter the hypoxic response of breast cancers in many ways, sometimes in opposite manners. Lactate stabilizes HIF-1 in oxidative condition, as well as destabilizes HIF-1 in hypoxia, increases cellular acidification, and mitigates HIF-1-driven inhibition of cellular respiration. We therefore tested the effect of lactate in MDA-MB-231 under hypoxia, finding that lactate can activate pathways associated with DNA replication, and cell cycling, as well as tissue morphogenesis associated with invasive processes. Using a bioengineered nano-patterned stromal invasion assay, we also confirmed that high lactate and induced HIF-1α gene overexpression can synergistically promote MDA-MB-231 dissemination and stromal trespass. Furthermore, using The Cancer Genome Atlas, we also surprisingly found that lactate in hypoxia promotes gene expression signatures prognosticating low survival in breast cancer patients. Our work documents that lactate accumulation contributes to increased heterogeneity in breast cancer gene expression promoting cancer growth and reducing patient survival.

Layered Double Hydroxide-Based PdCux@LDH Alloy Nanozyme for a Singlet Oxygen-Boosted Sonodynamic Therapy

Redox nanozymes have demonstrated tremendous promise in disrupting cellular homeostasis toward cancer therapy, but a dysfunctional competition of diverse activities makes it normally restricted by the complex tumor microenvironment (TME). As palladium nanocrystals can achieve the precise regulation of the enzyme-like activity by regulating exposed crystal planes, noble metal nanoalloys can enhance the enzyme-like activity by promoting electron transfer and enhanced active sites. Herein, bimetallic nanoalloys with optimized enzymatic activity were intelligently designed via the interaction between the Pd and layered double hydroxide, denoted as PdCux@LDH. This PdCux@LDH is able to produce long-lived singlet oxygen (1O2) with high efficiency and selectivity for ultrasound-improved cancer therapy. In addition, this PdCux@LDH nanozyme demonstrated unique surface-dependent multienzyme-mimicking activities for catalyzing cascade reactions: oxidase (OXD)- and catalase (CAT)-mimicking activities. Interestingly, ultrasound (US) stimulation can further improve the dual-enzyme-mimicking activities and impart superior reactive oxygen species (ROS) generation activity, thereby further consuming nicotinamide adenine dinucleotide (NADH) to cause mitochondrial dysfunction, resulting in a highly efficient alloy nanozyme-mediated cancer therapy. This work opens a new research avenue to apply nanozymes for effective sonodynamic therapies (SDT).

Lactate transport inhibition therapeutically reprograms fibroblast metabolism in experimental pulmonary fibrosis

Myofibroblast differentiation, essential for driving extracellular matrix synthesis in pulmonary fibrosis, requires increased glycolysis. While glycolytic cells must export lactate, the contributions of lactate transporters to myofibroblast differentiation are unknown. In this study, we investigated how MCT1 and MCT4, key lactate transporters, influence myofibroblast differentiation and experimental pulmonary fibrosis. Our findings reveal that inhibiting MCT1 or MCT4 reduces TGFβ-stimulated pulmonary myofibroblast differentiation in vitro and decreases bleomycin-induced pulmonary fibrosis in vivo. Through comprehensive metabolic analyses, including bioenergetics, stable isotope tracing, metabolomics, and imaging mass spectrometry in both cells and mice, we demonstrate that inhibiting lactate transport enhances oxidative phosphorylation, reduces reactive oxygen species production, and diminishes glucose metabolite incorporation into fibrotic lung regions. Furthermore, we introduce VB253, a novel MCT4 inhibitor, which ameliorates pulmonary fibrosis in both young and aged mice, with comparable efficacy to established antifibrotic therapies. These results underscore the necessity of lactate transport for myofibroblast differentiation, identify MCT1 and MCT4 as promising pharmacologic targets in pulmonary fibrosis, and support further evaluation of lactate transport inhibitors for patients for whom limited therapeutic options currently exist.

Monocarboxylate transporter-1 (MCT-1) inhibitors screened from autodisplayed FV-antibody library

Monocarboxylate transporter-1 (MCT-1) inhibitors were screened from the Fv-antibody library, which contained complementary determining region 3 with randomized amino acid sequences (11 residues) through site-directed mutagenesis. Fv-antibodies against MCT-1 were screened from the autodisplayed Fv-antibody library. Two clones were screened, and the binding affinity (KD) against MCT-1 was estimated using flow cytometry. The screened Fv-antibodies were expressed as soluble fusion proteins (Fv-1 and Fv-2) and the KD for MCT-1 was estimated using the SPR biosensor. The inhibitory activity of the expressed Fv-antibodies was observed in HEK293T and Jurkat cell lines by measuring intracellular pH and lactate accumulation. The level of cell viability in HEK293T and Jurkat cell lines was decreased by the inhibitory activity of the expressed Fv-antibodies. The binding properties of the Fv-antibodies to MCT-1 were analyzed using molecular docking simulations. Overall, the results showed that the screened Fv-antibodies against MCT-1 from the Fv-antibody library had high binding affinity and inhibitory activity against MCT-1, which could be used as potential therapeutic drug candidates for the MCT-1 inhibitor.