Lactylated Apolipoprotein C-II Induces Immunotherapy Resistance by Promoting Extracellular Lipolysis

Lactylation: From Homeostasis to Pathological Implications and Therapeutic Strategies

Lactylation, a recently identified post-translational modification, represents a groundbreaking addition to the epigenetic landscape, revealing its pivotal role in gene regulation and metabolic adaptation. Unlike traditional modifications, lactylation directly links metabolic intermediates, such as lactate, to protein function and cellular behavior. Emerging evidence highlights the critical involvement of lactylation in diverse biological processes, including immune response modulation, cellular differentiation, and tumor progression. However, its regulatory mechanisms, biological implications, and disease associations remain poorly understood. This review systematically explores the enzymatic and nonenzymatic mechanisms underlying protein lactylation, shedding light on the interplay between cellular metabolism and epigenetic control. We comprehensively analyze its biological functions in normal physiology, such as immune homeostasis and tissue repair, and its dysregulation in pathological contexts, including cancer, inflammation, and metabolic disorders. Moreover, we discuss advanced detection technologies and potential therapeutic interventions targeting lactylation pathways. By integrating these insights, this review aims to bridge critical knowledge gaps and propose future directions for research. Highlighting lactylation's multifaceted roles in health and disease, this review provides a timely resource for understanding its clinical implications, particularly as a novel target for precision medicine in metabolic and oncological therapies.

Lactate and lactylation in liver diseases: energy metabolism, inflammatory immunity and tumor microenvironment

Liver diseases pose a significant threat to human health. Lactate, a byproduct of glycolysis, serves various biological functions, including acting as an energy source, a signaling molecule, and a substrate for lactylation. Lactylation is a novel lactate-dependent post-translational modification that plays a role in tumor proliferation, the regulation of immune cell function, and the modulation of gene expression. In this paper, we summarize the roles of lactate and lactylation in energy metabolism, inflammatory immunity, and the tumor microenvironment, while also elucidating recent research advancements regarding lactate and lactylation in the context of hepatic fibrosis, non-alcoholic fatty liver disease, and hepatocellular carcinoma. Furthermore, lactate and lactylation are proposed as promising new targets for the treatment of liver diseases.

Cancer stem cells-derived exosomal TSPAN8 enhances non-stem cancer cells stemness and promotes malignant progression in PDAC

Cancer stem cells (CSC) play a crucial role in pancreatic ductal adenocarcinoma (PDAC) progression and therapeutic resistance. However, the underlying mechanisms and potential targeted treatment strategies remain poorly understood. In this study, we employed single-cell RNA sequencing and exosomal profiling, identifying TSPAN8-enriched exosomes secreted by CSC, which are associated with poor survival rates in PDAC patients. They enhanced stemness in the surrounding non-stem cancer cells (NSCC) by activating the Sonic Hedgehog (Hh) signalling pathway. This exosomal TSPAN8-Hh signalling axis significantly increases the clonogenic ability, invasiveness, and chemoresistance of PDAC cells. Furthermore, TSPAN8-enriched exosomes promoted a higher stem cell frequency, tumourigenicity, and tumour growth rate in vivo, confirming their critical roles in PDAC malignant progression. Our findings underscore the importance of TSPAN8-enriched exosomes for CSC-NSCC communication during PDAC progression.

Tumor Microenvironment Lactate: Is It a Cancer Progression Marker, Immunosuppressant, and Therapeutic Target?

The "Warburg effect" is a term coined a century ago for the preferential use of glycolysis over aerobic respiration in tumor cells for energy production, even under aerobic conditions. Although this is a less efficient mechanism of generating energy from glucose, aerobic glycolysis, in addition to the canonical anaerobic glycolysis, is an effective means of lactate production. The abundant waste product, lactate, yielded by the dual glycolysis in a tumor, has been discovered to be a major biomolecule that drives cancer progression. Lactate is a metabolic energy source that, via cell membrane lactate transporters, shuttles in and out of cancer cells as well as cancer cell-associated stromal cells and immune cells within the tumor microenvironment (TME). Additionally, lactate serves as a pH tuner, signaling ligand and transducer, epigenetic and gene transcription regulator, TME modifier, immune suppressor, chemoresistance modulator, and prognostic marker. With such broad functionalities, the production-consumption-reproduction of TME lactate fuels tumor growth and dissemination. Here, we elaborate on the lactate sources that contribute to the pool of lactate in the TME, the functions of TME lactate, the influence of the TME lactate on immune cell function and local tissue immunity, and anticancer therapeutic approaches adopting lactate manipulations and their efficacies. By scrutinizing these properties of the TME lactate and others that have been well addressed in the field, it is expected that a better weighing of the influence of the TME lactate on cancer development, progression, prognosis, and therapeutic efficacy can be achieved.

Mechanisms for Regulatory Effects of Exercise on Metabolic Diseases from the Lactate-Lactylation Perspective

Metabolic diseases, including cardiovascular diseases, type 2 diabetes mellitus (T2DM), osteoporosis, and non-alcoholic fatty liver disease (NAFLD), constitute a major global health burden associated with chronic morbidity and mortality. Lactate, once considered as a metabolic byproduct, has emerged as a key regulator of cellular reprogramming through lactylation, a novel post-translational modification (PTM) that dynamically couples metabolic flux to chromatin remodeling. Lactylation exerts dual regulatory roles as a signaling molecule via GPR81/GPR4-mediated pathways and as a substrate for the covalent modification of histones and metabolic enzymes. Pathologically, chronic hyperlactatemia suppresses mitochondrial biogenesis, driving metabolic cardiomyopathy through the epigenetic silencing of oxidative metabolism genes. Conversely, exercise-induced lactate surges transiently enhance insulin sensitivity via AMPK/PGC-1α/GLUT4 signaling, resolve inflammation through GPR81-mediated M2 macrophage polarization, and restore mitochondrial function via lactylation-dependent pathways. This review delineates lactylation as a spatiotemporal rheostat: chronic dysregulation perpetuates metabolic disorders, whereas acute exercise-mediated lactylation remodels transcriptional networks to restore metabolic homeostasis. Future research should integrate multiomics to clarify lactylation's spatiotemporal dynamics, tissue-specific thresholds, metabolism-immunity interactions, and metabolic-epigenetic crosstalk for the precision management of metabolic diseases.

HDAC2-Mediated METTL3 Delactylation Promotes DNA Damage Repair and Chemotherapy Resistance in Triple-Negative Breast Cancer

The current treatment of triple-negative breast cancer (TNBC) is still primarily based on platinum-based chemotherapy. However, TNBC cells frequently develop resistance to platinum and experience relapse after drug withdrawal. It is crucial to specifically target and eliminate cisplatin-tolerant cells after platinum administration. Here, it is reported that upregulated N 6-methyladenosine (m6A) modification drives the development of resistance in TNBC cells during cisplatin treatment. Mechanistically, histone deacetylase 2 (HDAC2) mediates delactylation of methyltransferase-like 3 (METTL3), facilitating METTL3 interaction with Wilms'-tumor-1-associated protein and subsequently increasing m6A of transcript-associated DNA damage repair. This ultimately promotes cell survival under cisplatin. Furthermore, pharmacological inhibition of HDAC2 using Tucidinostat can enhance the sensitivity of TNBC cells to cisplatin therapy. This study not only elucidates the biological function of lactylated METTL3 in tumor cells but also highlights its negative regulatory effect on cisplatin resistance. Additionally, it underscores the nonclassical functional mechanism of Tucidinostat as a HDAC inhibitor for improving the efficacy of cisplatin against TNBC.

The lactylation modification of proteins plays a critical role in tumor progression

Lactylation modifications have been shown to be a novel type of protein post-translational modifications (PTMs), providing a new perspective for understanding the interaction between cellular metabolic reprogramming and epigenetic regulation. Studies have shown that lactylation plays an important role in the occurrence, development, angiogenesis, invasion and metastasis of tumors. It can not only regulate the phenotypic expression and functional polarization of immune cells, but also participate in the formation of tumor drug resistance through a variety of molecular mechanisms. In this review, we review the latest research progress of lactylation modification in tumors, focusing on its mechanism of action in angiogenesis, immune cell regulation in tumor microenvironment (TME), and tumor drug resistance, aiming to provide a theoretical basis and research ideas for the discovery of new therapeutic targets and methods. Through the in-depth analysis of lactylation modification, it is expected to open up a new research direction for tumor treatment and provide potential strategies for overcoming tumor drug resistance and improving clinical efficacy.

Potential role of lactylation in intrinsic immune pathways in lung cancer

Lung cancer, one of the most lethal malignancies, has seen its therapeutic strategies become a focal point of significant scientific attention. Intrinsic immune signaling pathways play crucial roles in anti-tumor immunity but face clinical application challenges despite promising preclinical outcomes. Lactylation, an emerging research focus, may influences lung cancer progression by modulating the functions of histones and non-histone proteins. Recent findings have suggested that lactylation regulates key intrinsic immune molecules, including cGAS-STING, TLR, and RIG-I, thereby impacting interferon expression. However, the precise mechanisms by which lactylation governs intrinsic immune signaling in lung cancer remain unclear. This review presents a comprehensive and systematic analysis of the relationship between lactylation and intrinsic immune signaling pathways in lung cancer and emphasizes the innovative perspective of linking lactylation-mediated epigenetic modifications with immune regulation. By thoroughly examining current research findings, this review uncovers potential regulatory mechanisms and highlights the therapeutic implications of targeting lactylation in lung cancer. Future investigations into the intricate interactions between lactylation and intrinsic immunity are anticipated to unveil novel therapeutic targets and strategies, potentially improving patient survival outcomes.

A novel lactylation-related gene signature to predict prognosis and treatment response in lung adenocarcinoma

Background

Lactylation, a novel post-translational modification, has emerged as a critical regulatory mechanism in various biological processes, including tumor progression. However, its role and associated gene signatures in lung adenocarcinoma (LUAD) remain unclear.

Methods

RNA sequencing data of LUAD patients were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. Unsupervised clustering was used to identify lactylation-related genes. A risk prognostic model was constructed using least absolute shrinkage and selection operator regression analysis and subsequently validated. A nomogram was then employed to optimize the clinical applicability of the risk score. Additionally, various algorithms were used to explore the relationship between the risk score and immune infiltration levels, with model genes analyzed based on single-cell sequencing. The effects of RCCD1 knockdown on LUAD cell proliferation and migration were evaluated through CCK8 and transwell assays.

Results

Higher risk scores were associated with poorer overall survival prognosis. Immune analysis revealed that the risk score may play a role in regulating the tumor microenvironment. Additionally, these risk scores were found to be associated with chemotherapy drug sensitivity. A series of experiments further demonstrated that RCCD1 promotes LUAD cell proliferation and migration in vitro.

Conclusion

This study highlights the critical role of lactylation-related gene signatures in LUAD and their association with immune cell infiltration, providing insights into potential therapeutic targets and biomarkers for clinical application.

Global Profiling of Protein Lactylation in Human Hippocampi

PURPOSE

The hippocampus has long been associated with cognition and memory function, the implications of lysine lactylation (Kla), a recently identified post-translational modification (PTM), in the role of the hippocampus remain largely unexplored.

EXPERIMENTAL DESIGN

An LC-MS/MS bottom-up proteomics analysis of three human hippocampal tissue samples was applied to profile the lactylation map in human hippocampi under normal physiological conditions.

RESULTS

We identified 2579 quantifiable Class I lactylated sites in 853 proteins, of which contained four types of modification motifs. Cellular localization analysis implies that a majority of lactylated proteins were distributed in the cytoplasm. Functional enrichment analysis showed that lactylated proteins were mainly involved in energy metabolic pathways. In addition, we found that the lactylation on histones exhibits a certain degree of conservation across different tissues. Compared with previously reported lactylation databases, 213 lactylated proteins were identified for the first time in this study.

CONCLUSION AND CLINICAL RELEVANCE

The first global lactylated proteins atlas of human hippocampi was reported in this study. Our work provides a reliable foundation for further research on lactylation in the hippocampus under physiological conditions.

Metabolism of Tryptophan, Glutamine, and Asparagine in Cancer Immunotherapy-Synergism or Mechanism of Resistance?

Amino acids are crucial components of proteins, key molecules in cellular physiology and homeostasis. However, they are also involved in a variety of other mechanisms, such as energy homeostasis, nitrogen exchange, further synthesis of bioactive compounds, production of nucleotides, or activation of signaling pathways. Moreover, amino acids and their metabolites have immunoregulatory properties, significantly affecting the behavior of immune cells. Immunotherapy is one of the oncological treatment methods that improves cytotoxic properties of one's own immune system. Thus, enzymes catalyzing amino acid metabolism, together with metabolites themselves, can affect immune antitumor properties and responses to immunotherapy. In this review, we will discuss the involvement of tryptophan, glutamine, and asparagine metabolism in the behavior of immune cells targeted by immunotherapy and summarize results of the most recent investigations on the impact of amino acid metabolites on immunotherapy.

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.

Non-histone lactylation: unveiling its functional significance

Lactylation, a newly discovered protein posttranslational modification (PTM) in 2019, primarily occurs on lysine residues. Lactylation of histones was initially identified, and subsequent studies have increasingly demonstrated its widespread presence on non-histone proteins. Recently, high-throughput proteomics studies have identified a large number of lactylated proteins and sites, revealing their global regulatory role in disease development. Notably, this modification is catalyzed by lactyltransferase and reversed by delactylase, with numerous new enzymes, such as AARS1/2, reported to be involved. Specifically, these studies have revealed how lactylation exerts its influence through alterations in protein spatial conformation, molecular interactions, enzyme activity and subcellular localization. Indeed, lactylation is implicated in various physiological and pathological processes, including tumor development, cardiovascular and cerebrovascular diseases, immune cell activation and psychiatric disorders. This review provides the latest advancements in research on the regulatory roles of non-histone protein lactylation, highlighting its crucial scientific importance for future studies.

DLGAP5 enhances bladder cancer chemoresistance by regulating glycolysis through MYC stabilization

Rationale: Bladder cancer (BLCA), one of the most lethal urological tumors, exhibits high rates of recurrence and chemoresistance, particularly to gemcitabine (GEM). Understanding the mechanisms of GEM resistance is crucial for improving therapeutic outcomes. Our study investigates the role of DLGAP5 in promoting GEM resistance through modulation of glycolysis and MYC protein stability in BLCA cells. Methods: We utilized various BLCA cell lines and clinical tissue samples to analyze the impact of DLGAP5 on GEM resistance. Through biochemical assays, protein interaction studies, and gene expression analyses, we examined how DLGAP5 interacts with USP11 and MYC, assessed the effects on MYC deubiquitination and stability. The influence of these interactions on glycolytic activity and GEM resistance was also evaluated via mouse subcutaneous xenograft model and spontaneous BLCA model. Results: Our findings indicate that DLGAP5 enhances GEM resistance by stabilizing MYC protein via deubiquitination, a process mediated by USP11. DLGAP5 was found to facilitate the interaction between USP11 and MYC, promoting MYC-driven transcription of DLGAP5 itself, thereby creating a positive feedback loop. This loop leads to sustained MYC accumulation and increased glycolytic activity, contributing to GEM resistance in BLCA cells. Conclusion: The study highlights the critical role of DLGAP5 in regulating MYC protein stability and suggests that disrupting the DLGAP5-USP11-MYC axis may provide a novel therapeutic approach to overcome GEM resistance in BLCA. DLGAP5 represents a potential target for therapeutic intervention aimed at mitigating chemoresistance in bladder cancer BLCA.

Revisiting of Cancer Immunotherapy: Insight from the Dialogue between Glycolysis and PD-1/PD-L1 Axis in the Tumor Microenvironment

The interplay between metabolic pathways and immune escape has emerged as a captivating research area in oncobiology. Among these, the Warburg effect stands out as a hallmark metabolic reprogramming in cancer, characterized by elevated glucose utilization and excessive lactic acid production through anaerobic glycolysis. Key glycolytic enzymes not only fulfill the bioenergetic demands of cancer cells but also exhibit moonlighting roles, including regulation of epigenetic modifications, protein kinase activity, and immune escape mechanisms, thereby reshaping the tumor microenvironment. Tumor-specific vascular architecture facilitates lactate accumulation, which drives tumor progression by impairing immune cell function and acting as a signaling molecule to recruit immunosuppressive cells and modulate immune checkpoint pathways. The PD-1/PD-L1 co-stimulatory pathway plays a crucial role in negatively modulating the activation, proliferation, and cytokine secretion by T-lymphocytes. This review primarily focuses on elucidating the regulation and mechanisms underlying PD-1/PD-L1 signaling axis during glycolysis in tumor cells as well as surrounding cells. In the era of precision medicine, there is a particular interest in leveraging 18F-FDG PET/CT imaging as a valuable tool to assess PD-L1 expression status for more targeted therapeutic interventions. Additionally, the development of natural compounds capable of modulating metabolism opens new avenues for metabolism-based immunotherapy, though further studies are required to validate their in vivo efficacy.

Kanglaite alleviates lung squamous cell carcinoma through ferroptosis

Kanglaite, a compound predominantly composed of polyunsaturated fatty acids (PUFAs), has been employed in the clinical treatment of adenocarcinoma non-small cell lung cancer (NSCLC) in China for decades. However, its therapeutic efficacy and specific mechanism in the treatment of squamous NSCLC remains unexplored. In this study, we demonstrate that the co-treatment with ferric ion significantly enhances the cytotoxic effects of kanglaite by inducing ferroptosis in NCL-H1703, a cell line of human lung squamous cell carcinoma. Mechanistic investigations reveal that kanglaite induces mitochondrial dysfunction resulting in reactive oxygen species (ROS) excessive production, which is critical for the induction of ferroptosis. Further analysis shows that kanglaite suppresses the PI3K/AKT signaling pathway, leading to increased IP3 generation. IP3 subsequently binds to and activates IP3R, an endoplasmic reticulum (ER) calcium channel, exacerbating the excessive calcium transfer from the ER to mitochondria. The overloaded mitochondrial calcium contributes to its dysfunction and elevates ROS production. To optimize the synergistic effects of ferric ion and kanglaite, we develop a mesoporous silica-based nanodrug delivery system co-loaded with Kanglaite and Fe3O4, which offers several notable advantages, including reduced drug dosage and a faster therapeutic onset. Finally, in an NCL-H1703 xenograft model, the DMSN/Fe3O4-Kanglaite nanodrug significantly inhibited tumor growth. In conclusion, we identified the function and mechanism of kanglaite in treatment of squamous NSCLC and have developed a DMSN/Fe3O4-Kanglaite nanodrug, providing a superior therapeutic approach for the treatment of squamous NSCLC.

Lactylation in health and disease: physiological or pathological?

Lactate is an indispensable substance in various cellular physiological functions and plays regulatory roles in different aspects of energy metabolism and signal transduction. Lactylation (Kla), a key pathway through which lactate exerts its functions, has been identified as a novel posttranslational modification (PTM). Research indicates that Kla is an essential balancing mechanism in a variety of organisms and is involved in many key cellular biological processes through different pathways. Kla is closely related to disease development and represents a potential and important new drug target. In line with existing reports, we searched for newly discovered Kla sites on histone and nonhistone proteins; reviewed the regulatory mechanisms of Kla (particularly focusing on the enzymes directly involved in the reversible regulation of Kla, including "writers" (modifying enzymes), "readers" (modification-binding enzymes), and "erasers" (demodifying enzymes); and summarized the crosstalk between different PTMs to help researchers better understand the widespread distribution of Kla and its diverse functions. Furthermore, considering the "double-edged sword" role of Kla in both physiological and pathological contexts, this review highlights the "beneficial" biological functions of Kla in physiological states (energy metabolism, inflammatory responses, cell fate determination, development, etc.) and its "detrimental" pathogenic or inducive effects on pathological processes, particularly malignant tumors and complex nontumor diseases. We also clarify the molecular mechanisms of Kla in health and disease, and discuss its feasibility as a therapeutic target. Finally, we describe the detection technologies for Kla and their potential applications in diagnosis and clinical settings, aiming to provide new insights for the treatment of various diseases and to accelerate translation from laboratory research to clinical practice.

A rising star involved in tumour immunity: Lactylation

In recent years, continuous exploration worldwide has revealed that some metabolites produced during cellular and tissue metabolism can act as signalling molecules to exert different effects on the human body. These metabolites may act as cofactors for proteases or as post-translational modifications linked to proteins. Lactate, a traditional metabolite, is found at high levels in the tumour microenvironment (TME). Many studies have shown that lactate influences tumorigenesis and development via different mechanisms, not only through the metabolic reprogramming of tumours but also through its significant impact on tumour immunity. Previously, tumour cells were reported to use glucose and glutamine to fuel lactate metabolism; however, lactate serves not only as an energy source for tumour cells but also as a precursor substance needed for the post-translational modification of proteins. Recent studies identified a novel form of epigenetic modification, lactate-mediated histone lysine lactylation (Kla) and demonstrated that histone lactylation directly stimulates chromatin after gene transcription; consequently, lactylation has become a popular research topic in recent years. This article focuses on the research progress and application prospects of lactylation in the context of tumour immunity.