In both physiological and neoplastic contexts, glucose acts as the principal substrate for lactate generation, marking the end of the glycolytic cascade (Fig. 1) (22). Cellular uptake of glucose is predominantly mediated by glucose transporter (GLUT) proteins (23). Following internalization, glucose is metabolized to pyruvate under normoxic conditions. Subsequently, the bulk of this pyruvate enters the mitochondria via the mitochondrial pyruvate carrier, or is shuttled after conversion to undergo oxidative phosphorylation. Within the mitochondria, the tricarboxylic acid (TCA) cycle and electron transport chain drive the synthesis of ATP, releasing CO₂ and H₂O as byproducts (24) Conversely, in hypoxic or anaerobic environments, oxidative phosphorylation is compromised. To maintain redox homeostasis and sustain glycolysis, cytosolic pyruvate is reduced to lactate by lactate dehydrogenase (LDH) (25) Structurally, LDH exists as a tetramer formed by varying combinations of muscle subunits (M) and heart subunits (H), yielding five distinct isozymes: LDH-1 (4H), LDH-2 (3H1M), LDH-3 (2H2M), LDH-4 (1H3M) and LDH-5 (4M) (26). While these isoforms are bidirectional, LDHA (LDH-5) preferentially drives the reduction of pyruvate to lactate, thereby markedly fueling tumor progression, whereas LDHB (LDH-1) favors the oxidation of lactate back to pyruvate (27,28). Beyond glucose, research has highlighted glutaminolysis as an alternative metabolic route in cancer cells (29). Driven by the c-Myc proto-oncogene, glutamine enters the cytoplasm via specific transporters, including ASCT2 and SNAT2 (30). Once inside the cell, glutaminase (GLS) converts glutamine into glutamate, which is further processed into α-ketoglutarate by enzymes such as glutamate dehydrogenase to enter the TCA. Carbon derived from glutamine is then metabolized into oxaloacetate and subsequently malate, which is exported from the mitochondria. In the cytosol, malic enzyme converts malate to pyruvate, generating NADPH in the process, which is ultimately reduced to lactate by LDHA. Although this pathway typically serves as a secondary source of lactate, glutamine becomes the dominant carbon reservoir supporting cancer cell metabolism during glucose starvation (31). Furthermore, evidence suggests that under such glucose-deprived conditions, lactate enhances cell survival primarily by sustaining mitochondrial respiration through GLS1-mediated glutaminolysis (32).

Driven by metabolic reprogramming, lactate concentrations in cancer cells are markedly higher than those in the circulation or healthy parenchyma (33). Malignant tumors exhibit upregulated glycolytic flux even when oxygen availability is adequate and oxidative phosphorylation remains functional. Specifically, through aerobic glycolysis, tumor tissues generate lactate levels that are 10- to 100-fold higher than those produced via complete mitochondrial glucose oxidation (34). Characterized as the Warburg effect, this phenomenon describes the propensity of cancer cells to prioritize glycolysis and lactate synthesis over oxidative phosphorylation, despite the presence of oxygen (3). This metabolic shift is essential for meeting neoplastic requirements for bioenergetics, redox homeostasis and biosynthetic precursors, a process accompanied by extensive reprogramming of metabolic enzymes and transport proteins (35,36). Consequently, the accumulation of substantial lactic acid stands as a definitive outcome of this metabolic reconfiguration.

Following its efflux from glycolytic cells, lactate enters the systemic circulation, where, under homeostatic conditions, it functions as a vital metabolic substrate for the myocardium, brain and skeletal musculature (37–39). To avert the onset of acidosis caused by supraphysiological lactate levels, rapid metabolic clearance and irreversible elimination mediated by LDH are essential for maintaining tissue equilibrium (40). Concurrently, the accumulation of lactate stimulates hepatic gluconeogenesis, allowing the liver to recycle lactate into glucose via the Cori cycle for redistribution into the vascular system (41). In cancer, where metabolic reprogramming drives excessive lactate generation, efflux is predominantly facilitated by monocarboxylate transporters (MCTs), with MCT4 serving as a pivotal mediator of this export mechanism (42). Furthermore, in hypoxic microenvironments, MCT1 also contributes to the extracellular transport of lactate (43).

The TME constitutes a complex ecosystem comprising malignant cells, stromal elements such as endothelial cells and cancer-associated fibroblasts (CAFs), and infiltrating immune populations. These cellular components are embedded within a non-neoplastic extracellular matrix rich in bioactive peptides, including cytokines, chemokines, antibodies and growth factors (44). Upon accumulation in the TME, lactate actively potentiates immune escape by dampening the functional activity of immune cells and suppressing the synthesis of inflammatory mediators (45). Beyond its metabolic function, lactate acts simultaneously as an energy substrate, a signaling messenger and a potent immunosuppressive agent, thereby orchestrating diverse cellular behaviors (46). Notably, lactate buildup sustains a chronically acidic extracellular pH; this localized acidic milieu is a critical driver of angiogenesis, therapeutic resistance, immunosuppression and metastatic dissemination (47–50). Specifically, the acidic conditions compromise cytokine secretion by monocytes (51) and impair the cytotoxic capabilities of natural killer (NK) and NKT cells (52,53), ultimately fostering an environment conducive to tumor proliferation. Furthermore, lactate stimulates the upregulation of vascular endothelial growth factor, ensuring sufficient oxygen and nutrient delivery to support neoplastic growth and neovascularization (54). In colorectal cancer (CRC), research has indicated that lactic acidosis blunts the activity of antitumor immune cells and inhibits the phagocytic capacity of tumor-associated macrophages (TAMs). Concurrently, metabolic stress and nutritional deprivation favor the differentiation of regulatory T cells (Tregs) and M2-polarized macrophages, the latter of which promote tumor expansion and metastasis (55). Collectively, these mechanisms orchestrate robust tumor immune evasion (56). In summary, the synergistic effects of TME acidification and sustained high lactate levels drive tumor progression by disabling immune surveillance and fortifying cancer cells against host defenses.

Mechanistic investigations have confirmed that GPR81, a lactate receptor, is a pivotal modulator of both tumor proliferation and metastatic progression (57). Evidence from in vitro and in vivo models has suggested that GPR81 regulates metabolic processes in cancer cells through autocrine loops and simultaneously drives immune escape via paracrine mechanisms (58,59). In breast cancer (BC), in vitro experiments have revealed elevated GPR81 levels relative to healthy mammary epithelium (60), and knockdown of GPR81 markedly suppresses BC cell proliferation (61). Furthermore, activation of GPR81 by lactate induces PD-L1 upregulation, thereby promoting immune evasion (62). Additionally, experimental findings have identified a signaling axis in which lactate activates STAT3, which subsequently binds to the GPR81 promoter to induce GPR81 transcription (57). In lung cancer (LC) models, inhibition of GPR81 signaling reduces PD-L1 protein abundance (63). Moreover, silencing GPR81 in hypopharyngeal squamous cell carcinoma cells potentiates cisplatin-induced apoptosis (64). Preclinical studies have also demonstrated that antagonizing GPR81 augments the therapeutic efficacy of metformin (65,66). From a clinical perspective, the contribution of lactate metabolism to metastasis is corroborated by correlative analyses in patient populations (67). Driven by the Warburg effect, LDHA expression shows a direct linear relationship with lactate levels, and its depletion has been observed to inhibit metastasis in hepatocellular carcinoma (HCC) (68,69). In human BC tissues, the potassium channel KCNK1 is markedly upregulated and is associated with poor prognosis. Mechanistically, KCNK1 physically interacts with LDHA to enhance lactate production, creating a positive feedback loop that drives metastatic spread (70). Furthermore, clinical data have indicated that patients with cervical cancer (CC) exhibiting high LDH levels are at a greater risk for deep stromal invasion and nodal metastasis (71). Similarly, in cases of brain metastasis, elevated serum LDH is inversely associated with overall survival (OS) (72).

Histones are fundamental chromatin proteins that compact the eukaryotic genome into nucleosomes and higher-order chromosomal structures, thereby maintaining physiological stability (73,74). PTMs of these proteins provide a crucial regulatory layer, influencing DNA-dependent processes to facilitate cellular differentiation and optimize gene function. Furthermore, sequence variants within histone families enrich the chromatin landscape, offering diverse mechanisms for signaling and regulation. While initial reports characterized histone lactylation broadly, a recent study by Zhang et al (75) employed chemical analysis to differentiate three distinct isomers: Lysine L-lactylation (Kl-la), N-ε-(carboxyethyl)-lysine (Kce) and D-lactyllysine (Kd-la). Notably, this investigation established Kl-la as the dominant isomer on histones, specifically induced by upregulated glycolytic flux. This distinction is particularly relevant in oncology, given that the Warburg effect drives tumor cells to generate L-lactate, the specific substrate for Kl-la. Conversely, Kd-la originates from methylglyoxal, a toxic metabolic byproduct. This suggests that Kl-la serves as the primary functional bridge connecting metabolic reprogramming to tumor epigenetics, whereas the specific roles of Kce and Kd-la within the TME warrant further independent study (75). Utilizing high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) on trypsinized core histones from human MCF-7 cells, Zhang et al (9) pioneered the detection of a specific 72.021 Da mass shift on lysine residues. The authors further validated the widespread occurrence of histone lysine lactylation using metabolic isotope labeling, thereby establishing a cornerstone for Kl-la research. While this work focused on characterizing histone lactylation as a novel epigenetic regulator of transcription, subsequent research broadened this perspective. Subsequently, Gaffney et al (76) detected lactylation on various metabolic enzymes associated with glycolysis, suggesting that this modification could exert negative feedback control on glycolytic flux. The findings of this previous study underscored the ubiquity of lactylation across human tissues, demonstrating that this modification is not confined to histones but also exerts regulatory effects on non-histone proteins.

Non-histone lactylation is increasingly recognized as a pivotal regulator of a range of cellular processes in both physiological and pathological contexts. The functional impact and enzymatic dynamics of this modification are dictated by the subcellular positioning and protein-protein interactions of the specific substrates, employing varied mechanisms to modulate target protein activity (77). Broadly, lactate-driven protein modification is markedly ubiquitous across diverse biological systems. In the context of Toxoplasma gondii, a prevalent parasitic pathogen, investigations have revealed that lactylated proteins are present in various subcellular organelles. These modifications are closely linked to vital processes such as mRNA splicing, glycolytic metabolism, aminoacyl-transfer RNA (tRNA) biosynthesis, RNA transport and several signaling cascades (e.g., DNA damage repair and mTOR signaling) (78). Similarly, proteomic analyses in yaks have identified 421, 308 and 650 lactylated proteins in cardiac, muscular and hepatic tissues, respectively; these modifications are integral to metabolic regulation and the maintenance of physiological homeostasis (79). Furthermore, in the plant kingdom, researchers have characterized 927 specific lactylation sites across 394 proteins in wheat (80). Furthermore, mechanistic inquiries into specific non-histone targets have yielded profound insights. For example, the lactylation of α-myosin heavy chain has been shown to maintain sarcomeric integrity and functionality in a mouse model, effectively mitigating the progression of heart failure (81). In oncology, MRE11, a key mediator of homologous recombination (HR), has been reported to undergo lactylation at residue K673, a modification that reduces tumor cell susceptibility to chemotherapy. Consequently, inhibiting MRE11 lactylation restores the sensitivity of cancer cells to agents such as cisplatin and poly(ADP-ribose) polymerase inhibitors (PARPi) (82).

Elucidating the precise regulatory machinery of lactylation necessitates a thorough characterization of its enzymatic effectors. This regulatory system is orchestrated by three distinct classes of proteins: ‘Writers’ that deposit lactyl moieties onto specific residues, ‘erasers’ that catalyze the removal of these modifications, and ‘readers’ that possess specialized domains to interpret site-specific epigenetic codes. Drawing parallels to the successful therapeutic targeting of acetylation enzymes in oncology (83), it is postulated that the enzymatic regulators of lactylation hold comparable potential as precision targets for treating cancer and other pathologies.

The bromodomain-containing protein p300, traditionally recognized for catalyzing histone H3 acetylation to drive transcription (84), was established by Zhang et al (9) to be a dual-function enzyme also capable of mediating histone lactylation. Mechanistic studies have revealed that p300 overexpression can augment histone lactylation in 293T cells, whereas its depletion was shown to markedly diminish H3 lysine 18 lactylation (H3K18la) in both HCT116 and 293T cell lines (85,86). Subsequent investigations have broadened the functional scope of p300. For example, Minami et al (87) demonstrated that p300 facilitated osteoblast differentiation through lactate-induced histone modification. In cardiovascular pathology, Dong et al (88) reported that lipid peroxidation accelerated atherosclerosis by triggering endothelial-to-mesenchymal transition, a process driven by lactate-dependent H3K18la via the p300/ASF1A complex. Furthermore, therapeutic interventions targeting p300 have shown promise; Wang et al (89) reported that andrographolide alleviated aortic valve calcification by disrupting p300-mediated histone H3 lactylation. p300 also modulated inflammatory responses; its inhibition suppressed the lactylation of Yin-Yang 1, thereby mitigating microglial inflammation (90). In oncology, p300 has been characterized as the primary histone lactylation writer in pancreatic ductal adenocarcinoma (PDAC) (91). Additionally, in intrahepatic cholangiocarcinoma, p300 has been reported to catalyze the lactylation of nucleolin (NCL) at lysine (K)477, a modification that fuels tumor proliferation and invasion (92).

Beyond p300, the repertoire of lactyltransferases has expanded. Ju et al (93) identified alanyl-tRNA synthetase (AARS)1 as an enzyme capable of utilizing ATP and lactate to directly catalyze protein lactylation. Similarly, the acetyltransferase KAT8 has been implicated in depositing lactyl marks on numerous substrates. Notably, KAT8 deficiency has been shown to markedly impair CRC growth within lactate-rich microenvironments, highlighting its potential as a therapeutic target (94).

Recent evidence has also highlighted the role of 5-methylcytosine (m5C) in CRC progression (95,96). The m5C methyltransferase NSUN2 is frequently upregulated and drives oncogenesis in CRC. A critical signaling axis involves NSUN2 (as the writer) and YBX1 (as the reader) regulating ENO1, thereby reprogramming glucose metabolism to increase lactate production. This accumulated lactate subsequently enhances NSUN2 transcription via H3K18la and promotes NSUN2 lactylation at K356, a modification essential for RNA binding. This establishes a positive feedback loop within the NSUN2/YBX1/m5C-ENO1 axis, effectively linking metabolic shifts with epigenetic remodeling (95). Additionally, TIP60 acts as the specific writer for NBS1 lactylation at K388, a modification that facilitates HR repair (97). In hepatic stellate cell activation, hexokinase 2 (HK2) serves a requisite role in driving histone lactylation-dependent gene expression; consequently, HK2 knockdown mitigates stellate cell activation and liver fibrosis (98). Collectively, these findings underscore the pivotal roles of p300, AARS1, KAT8, NSUN2, TIP60 and HK2 as key enzymatic effectors of protein lactylation.

The superfamily of histone lysine deacetylases (HDACs) is traditionally divided into two primary lineages: The classical zinc-dependent HDACs and the NAD⁺-requiring Sirtuin (SIRT) family (99). While the classical zinc-dependent HDAC1-3 are characterized as robust deacylase complexes (100), the SIRT family generally demonstrates comparatively limited delactylase efficacy (101). Specific functional roles have been delineated for these enzymes; for example, Fan et al (102) reported that HDAC2 acted as a negative regulator of angiogenesis by diminishing H3K9 lactylation. Concurrently, HDAC2 has been implicated as a putative eraser of histone lactylation within PDAC cells (91). During genomic maintenance, HDAC3 serves as the specific delactylase for NBS1 during DNA repair processes (97). Furthermore, Zu et al (103) established SIRT2 as a proficient eraser of histone lactylation. This is exemplified by the regulation of METTL16, an atypical methyltransferase: Under copper stress, METTL16 undergoes lactylation at K229, a modification that is antagonized by SIRT2. Collectively, current evidence positions HDAC1-3 and SIRT2 as pivotal regulatory enzymes governing the removal of lactyl modifications.

During PTM, the functional execution of an epigenetic mark depends not merely on its deposition by a writer, but crucially on its subsequent recognition by specialized effector proteins. These proteins, termed readers, possess distinct structural domains engineered to identify and bind to specific site-specific modifications (104). While the characterization of readers specific to protein lactylation has historically lagged behind that of writers and erasers, the field has seen advances over the past 2 years. As aforementioned, YBX1 has been identified as a direct reader of lactylated ENO1 in CRC, serving an integral role in the NSUN2/YBX1/m5C-ENO1 signaling axis; a discovery with profound implications for understanding CRC pathogenesis. Hu et al (105) used proteomic profiling of H3K18la immunoprecipitates to identify the specific recruitment of Brg1 during cellular reprogramming. Their analysis demonstrated co-enrichment of H3K18la and Brg1 at the promoters of genes governing pluripotency and epithelial junction integrity. Furthermore, biochemical validation of the physical interaction between Brg1 and H3K18la effectively established Brg1 as a bona fide reader of histone lactylation (105). Despite these isolated advances, the current landscape of lactylation reader research remains nascent and limited in scope, underscoring an urgent need for more comprehensive mechanistic investigations to fully map this regulatory network.

Historically, lactyl-CoA was primarily recognized for its industrial utility as a foundational building block in the biosynthesis of biodegradable and biocompatible lactate-derived copolymers (106). From a biochemical perspective, the generation of this intermediate is a prerequisite for protein lactylation, a process that depends on the conversion of lactate to lactyl-CoA catalyzed by the enzyme acyl-CoA transferase. To elucidate this mechanism, Zhang et al (106) performed comprehensive enzymological characterization, encompassing screening, cloning and purification, of five candidate lactyl-CoA synthetases, specifically evaluating the stability profiles of the three variants that demonstrated superior specific activity. Furthermore, the endogenous existence of this metabolite has been definitively confirmed in vivo, particularly in mouse liver and muscle tissues. By employing liquid chromatography-high-resolution mass spectrometry validated against synthetic standards, investigators have successfully verified the ubiquitous presence of lactyl-CoA across a range of mammalian cell lines and murine tissues (107).

In hypoxic microenvironments, the activation of hypoxia-inducible factor (HIF)-1α acts as a critical driver of malignancy, fostering tumor cell migration, invasion and metastatic spread through the promotion of epithelial-mesenchymal transition (110). Mechanistically, HIF-1α functions as a master transcriptional regulator that drives glycolytic machinery (111). By orchestrating the expression of genes essential for glycolysis, HIF-1α indirectly amplifies lactate generation, which subsequently fuels protein lactylation. This regulatory axis has been corroborated by studies utilizing PX-478, a potent HIF-1α inhibitor; inhibition of HIF-1α was shown to abrogate the surge in extracellular lactate levels, thereby confirming its modulatory role in lactylation substrate availability (112,113). Beyond indirect regulation, hypoxia may also exert direct control over lactylation-associated enzymes. Recent findings have indicated that intracellular hypoxia triggers mitochondrial protein lactylation via a distinct mechanism: It induces the accumulation of mitochondrial AARS (AARS2). Acting as a non-canonical lysine lactyltransferase, AARS2 targets and inactivates key metabolic enzymes, specifically the pyruvate dehydrogenase complex (PDC) and carnitine palmitoyltransferase 2 (114).

There is a distinct association between p53 status and the expression profile of proteins governing aerobic glycolysis in HCC cells. Functionally, the stabilization and subsequent activation of p53 effectively downregulate genes driving aerobic glycolysis and restricts glycolytic flux; this regulatory action notably diminishes lactate generation, thereby impeding the progression of HCC (115). Other studies in HCC have demonstrated that interrupting the p53/isocitrate dehydrogenase 1/HIF-1α signaling cascade shifts cellular metabolism toward mitochondrial respiration while suppressing aerobic glycolysis (116,117). This metabolic switch results in reduced lactate output, further arresting malignant advancement (116). Collectively, these findings indicate that p53 exerts its regulatory influence on lactylation primarily by indirectly modulating the glycolytic pathway.

While histone lactylation is recognized as a canonical epigenetic modifier, emerging proteomic landscapes have unveiled a ubiquitous role for this modification across the non-histone proteome, where it critically governs protein stability, enzymatic kinetics and interactome dynamics. These non-histone substrates primarily cluster into three functional domains: Metabolic regulation, DNA damage response and signal transduction, which together orchestrate complex networks that fuel tumorigenesis.

Metabolic enzymes are primary targets of lactylation, establishing a feed-forward mechanism that amplifies the Warburg effect. Specific examples include the lactylation of PDHX at K488 in HCC, which impairs complex assembly to block oxidative phosphorylation while boosting glycolysis (118). Furthermore, aldolase A (ALDOA) lactylation diminishes its binding to DEAD-box helicase 17 (DDX17), a molecular event that augments the stem-like properties of liver cancer cells (119). In immunometabolism, the modification of pyruvate kinase M2 (PKM2) at K62 acts as a switch for macrophage reprogramming, effectively dampening inflammatory outputs (120).

In genomic integrity, lactylation modulates DNA repair machinery, directly underpinning therapeutic resistance. The HR factor MRE11 is lactylated at K673, a modification that potentiates DNA repair efficiency, and consequently reduces cancer cell susceptibility to cisplatin and PARPi (82). Similarly, lactylation events on NBS1 (at K388) and XRCC1 (at K247) have been characterized as drivers of chemo- and radioresistance across diverse malignancies (97,121). This modification tunes critical signaling effectors governing proliferation and immune escape. For example, in Tregs, lactylation of Moesin at K72 amplifies TGF-β signaling, thereby facilitating Treg differentiation and fostering an immunosuppressive niche (122). In intrahepatic cholangiocarcinoma, p300-mediated lactylation of NCL has been shown to drive tumor expansion and invasion by regulating RNA splicing (92). For a comprehensive synthesis of these findings, the specific substrates, modification sites and downstream consequences are systematically detailed in Table I.

Metabolic reprogramming has been widely recognized as a fundamental driver of tumorigenesis and malignant progression (123). To fuel sustained proliferation, neoplastic cells undergo profound bioenergetic restructuring (33). Lactylation has emerged as a pivotal epigenetic modulator, altering chromatin topology to influence transcriptional landscapes. Crucially, this modification creates a bidirectional regulatory axis; it not only reshapes the transcriptional and functional profiles of key glycolytic enzymes (124), but also serves as a molecular bridge connecting metabolism to epigenetics, thereby directly upregulating metabolism-associated genes (125).

As established, LDHA functions as the central enzyme catalyzing pyruvate-to-lactate conversion. Concurrently, GLUT3 is integral to glucose uptake and glycolysis in cancer cells (126). Single-cell sequencing data have revealed the notable upregulation of GLUT3 in both primary and metastatic lesions. Notably, GLUT3 expression has been shown to be positively associated with LDHA levels and lactylation pathways; in gastric cancer, GLUT3 has been reported to modulate lactylation dynamics, thereby driving disease progression (127). In esophageal carcinoma, hypoxic conditions trigger the lactylation of Axin1 and SHMT2 proteins, a modification that further potentiates cell proliferation, metastasis and stemness features (128,129).

The landscape in non-small cell LC (NSCLC) appears multifaceted. Evidence has suggested that lactate can suppress the mRNA levels of glycolytic enzymes (HK1 and PKM) and TCA cycle enzymes (SDHA and IDH3G); chromatin immunoprecipitation assays have confirmed an enrichment of histone lactylation at the promoters of HK1 and IDH3G, indicating that lactate regulates metabolism partly through epigenetic repression (130). Conversely, hypoxia-induced lactylation of SOX9 has been reported to amplify glycolytic activity, thereby enhancing stemness and invasive potential in NSCLC cells (131). Thus, lactylation exerts complex, context-dependent effects on glycolysis within this malignancy.

In LC models, the IGF1/IGF1R axis is critical for metabolic regulation. Research has indicated that stability of the IGF1R oncogene is enhanced by lactate-mediated lactylation, establishing a positive feedback loop that further fuels glycolysis and lactate generation (132). In pancreatic adenocarcinoma, studies have linked elevated global histone lactylation to poor prognosis (91,133). Mechanistically, EP300 has been identified as the writer catalyzing lactylation at K128 of NMNAT1. This modification supports the nuclear NAD⁺ salvage pathway, thereby sustaining tumor growth (32). Furthermore, in CC, lactate has been shown to upregulate and stabilize DCBLD1, a type I protein containing an LCCL domain, via lactylation. This stabilization activates the pentose phosphate pathway, ultimately promoting proliferation and metastasis (134). Collectively, these findings underscore protein lactylation as a critical nexus integrating lactate metabolism, oncogenic signaling and clinical outcomes.

Functionally and structurally, the TME constitutes a sophisticated ecosystem orchestrated by a heterogeneous array of cell types, including endothelial cells, CAFs, mesenchymal stromal cells and various immune cell subsets, such as macrophages, dendritic cells, NK cells, T cells and B cells. Crucially, this multicellular environment establishes a permissive niche that actively supports protein lactylation. Therefore, dissecting the crosstalk between these TME constituents and lactylation pathways, particularly their contributions to tumorigenesis, invasive behavior, and immune evasion, holds potential to advance the frontiers of cancer immunotherapy.

Immune populations represent pivotal constituents of the TME; consequently, elucidating the dynamics of lactylation within these cells is of profound scientific significance (Fig. 2) (135).

Traditionally, the immune system is conceptualized as a defensive apparatus tasked with distinguishing self from non-self, orchestrating innate and adaptive responses to eliminate threats and preserve tissue homeostasis (136). Within this framework, T lymphocytes occupy a central position (137). As the linchpins of cellular immunotherapy and tumor surveillance, T cells are responsible for antigen recognition, cytokine secretion, and the coordination of broad immune responses to thwart malignant invasion. Based on their distinct surface markers and functional profiles, these lymphocytes are further categorized into specialized subsets (138).

Research highlights the notable sensitivity of T lymphocytes to the lactate-rich milieu of the TME, where lactate signaling fundamentally alters cellular signaling and therapeutic outcomes (139). Specifically, lactate accumulation drives histone lactylation, thereby compromising histone transcriptional activity in CD4⁺ and CD8₊ cells. This epigenetic suppression reduces cytokine production and cytolytic efficacy, ultimately blunting lymphocyte responses and favoring tumor progression (140–142).

Quinn et al (143) revealed that under glucose-deprived, lactate-rich conditions, glycolytic effector T cells undergo profound metabolic inhibition. High lactate concentrations drive LDH to reduce NAD⁺ to NADH, thereby disrupting the cellular redox balance. This depletion of NAD⁺ impairs downstream enzymatic reactions that depend on GAPDH and PGDH, creating a bottleneck that depletes glycolytic intermediates and serine, a critical metabolite derived from 3-phosphoglycerate and essential for T-cell proliferation. Notably, serine supplementation can effectively rescue T-cell proliferation from this lactate-induced reductive stress (143). Beyond metabolic restriction, lactate impairs the T-cell redox system. Pharmacological intervention using dichloroacetate to target tumor lactate metabolism has been shown to reinvigorate T-cell antitumor immunity (144).

In head and neck squamous cell carcinoma (HNSCC), H3K9 lactylation is linked to immunotherapy resistance, activating immune checkpoints via IL-11 and causing CD8⁺ T-cell dysfunction (142). Furthermore, GLUT10 has been implicated as a crucial GLUT for CD8⁺ T-cell activation. Lactate accumulates in the TME and directly binds to GLUT10, blocking glucose uptake; therefore, disrupting this lactate-GLUT10 interaction offers a novel therapeutic avenue to restore CD8⁺ cytotoxicity (145).

The clinical efficacy of PD-1 blockade hinges on the balance between effector CD8⁺ T cells and immunosuppressive Tregs. In highly glycolytic tumors (such as MYC-amplified or hepatic cancers), Tregs exhibit higher PD-1 levels than effector T cells. This occurs because Tregs in low-glucose environments actively import lactate via MCT1, thereby driving nuclear translocation of NFAT1 and upregulating PD-1, whereas effector expression is suppressed. Thus, a lactate-rich TME selectively upregulates PD-1 on Tregs (146). Additionally, lactate fuels Treg generation through the specific lactylation of Moesin at K72. This modification strengthens the interaction between Moesin and TGF-β receptor I and activates downstream SMAD3 signaling. Consequently, combining anti-PD-1 therapy with LDH inhibitors yields superior efficacy over monotherapy (122). These findings suggest that targeting lactylation-driven Treg differentiation constitutes a promising strategy to provide novel options in cancer treatment.

As cornerstones of the innate immune architecture, macrophages are defined by their marked phenotypic malleability. This high plasticity allows them to orchestrate responses to diverse physiological and pathological cues by transitioning between functional states (147,148). This heterogeneity is traditionally conceptualized as ‘polarization’, a spectrum often simplified into a dichotomy dictated by the microenvironment: The classically activated (M1) and alternatively activated (M2) phenotypes, which generally exhibit antagonistic roles (149). M1 macrophages are characterized by robust antigen-presenting capabilities, and the secretion of proinflammatory cytokines such as IL-12, IL-23 and TNF-α (150). Conversely, the M2 phenotype is predominantly aligned with anti-inflammatory processes, and is strongly implicated in fostering tumor proliferation and metastasis (55). Emerging evidence has suggested that metabolic rewiring is not merely a consequence but a prerequisite for this phenotypic switching (151). Specifically, the lactylation of PKM2 at K62 has been isolated as a pivotal mechanism driving the metabolic reprogramming essential for macrophage inflammatory activation (120).

In the TME, TAMs display notable heterogeneity, adapting their function in response to niche-specific signals. While it is established that metabolic shifts accompany these phenotypic changes, recent findings have argued that metabolic reprogramming actively dictates the activation state and function of macrophages (152,153). For example, in CRC, RARγ downregulation in TAMs is associated with poor clinical outcomes. Mechanistically, tumor-derived lactate drives H3K18 lactylation, which transcriptionally suppresses the RARγ gene in macrophages, thereby accelerating disease progression (154). Both bioinformatics profiling and real-world clinical data corroborate that elevated H3K18 lactylation serves as a negative prognostic indicator (155,156). Notably, the regulation is bidirectional: Macrophages can also modulate the lactylation landscape. In glioblastoma (GBM) models, monocyte-derived macrophages have been shown to actively erase histone lactylation. This erasure facilitates the intratumoral accumulation of T cells and suppresses tumor growth (157). Consequently, a reciprocal regulatory axis between macrophages and lactylation collectively shapes the trajectory of tumor initiation and development.

In addition to macrophages and T cells, high lactate accumulation in the TME also impairs the function and cytokine release of DCs (21). In tumor-infiltrating myeloid cells (TIMs), the upregulation of lactylation enzyme METTL3 induces immunosuppressive effects in CRC (158). Lactic acid inhibits the differentiation and antigen presentation of DCs, promoting their transformation into tumor-associated DCs (TADCs), which results in a reduction of IL-12 secretion and impaired immune response (159). The transcription factor SREBP2, influenced by lactic acid, further regulates the maturation of DCs and their immunosuppressive functions, thereby inhibiting anti-tumor immune responses (160).

Leveraging established gene signatures associated with histone lactylation, a study utilized single-sample gene set enrichment analysis to assess the cellular landscape of the TME. The analysis highlighted a clear stratification; the low-lactylation cohort was characterized by a robust infiltration of NK cells and cytotoxic lymphocytes. Conversely, the high-lactylation group exhibited a predominance of stromal elements, specifically showing enriched populations of fibroblasts and endothelial cells (125).

CAFs represent a prominent and diverse mesenchymal population within the TME, serving a pivotal role in orchestrating malignant behaviors (161). In clear cell renal cell carcinoma (ccRCC), histone lactylation in CAFs has been shown to drive tumor progression, with TIMP1 identified as a central downstream target of this epigenetic modification (162). Furthermore, in gastric cancer, the epigenetic landscape of CAFs, specifically defined by H3K18la levels, critically affects the therapeutic efficacy of immune checkpoint inhibitors by regulating PD-L1 abundance (163). Regarding the vascular component, tumor endothelial cells typically remain quiescent under physiological conditions. However, in lung adenocarcinoma (LUAD), SLC25A29 has emerged as a vital prognostic determinant linked to tumor staging. Mechanistic studies have confirmed that SLC25A29 expression is epigenetically regulated by H3K14 and H3K18 lactylation at its promoter (164,165). Functionally, downregulation of SLC25A29 promotes endothelial proliferation and migration while suppressing apoptosis, thereby accelerating LUAD progression (166).

Epigenetic dysregulation is increasingly recognized as a cornerstone of tumorigenesis. As a newly defined epigenetic modification, lactylation orchestrates tumor development by regulating both histone and non-histone substrates, while simultaneously modulating metabolic plasticity (167–169). HCC represents a highly lethal malignancy and ranks as the second leading cause of cancer mortality globally (170). Its pathogenesis is frequently preceded by chronic liver injury, stemming from hepatitis B, hepatitis C or steatohepatitis, where the risk of mortality scales exponentially with the severity of fibrosis (171). The pathogenic continuum from fibrosis to cirrhosis, and ultimately to HCC, involves complex regulatory shifts (172).

Emerging evidence has implicated lactylation, a structural analog of acetylation, as a driver of this fibrotic progression. Notably, gene signatures marked by histone lactylation in fibrotic tissues are concomitantly upregulated in HCC, suggesting a direct mechanistic link between fibrotic remodeling and hepatocarcinogenesis (173). Furthermore, liver cancer stem cells (LCSCs) underpin the phenotypic heterogeneity of HCC. Proteomic profiling has unveiled that ALDOA undergoes lactylation at residues K230 and K322; mechanistically, this modification disrupts the physical interaction between ALDOA and DDX17, thereby potentiating DDX17 function and reinforcing the stem-like phenotype of LCSCs (119).

In BC, The Cancer Genome Atlas analysis has highlighted the pivotal role of lactylation (174). Specifically in triple-negative BC (TNBC), an aggressive subtype, elevated histone H4 lysine 12 lactylation (H4K12la) is inversely associated with OS (175). This poor prognosis is driven by the H4K12la-mediated transcriptional suppression of Schlafen 5, delineating a novel oncogenic axis (176). Similarly, in ovarian cancer (OC), the chemokine CCL18 is frequently upregulated; this is epigenetically driven by H3K18 lactylation, which actively fuels tumorigenesis (177).

Uncontrolled proliferation and metastatic dissemination represent defining hallmarks of malignancy, with the latter accounting for ~90% of cases of cancer-related mortality (178,179). Against this backdrop, the rapidly expanding field of lactylation research offers novel therapeutic paradigms for the treatment of refractory tumors. In HCC, lactylation drives malignancy through dual epigenetic and metabolic mechanisms. First, pyrroline-5-carboxylate reductase 1 increases IRS1 transcriptional activity by modulating H3K18 lactylation at its promoter, thereby increasing proliferation and metastasis (180). Moreover, the metabolic shift from oxidative phosphorylation to aerobic glycolysis is cemented by inactivation of the mitochondrial PDC. Specifically, lactylation of the PDHX component at K488 impairs PDC assembly, a critical event that accelerates HCC progression (118).

In TNBC, elevated glycolytic flux initiates a specific oncogenic cascade: It promotes histone lactylation at the c-Myc promoter, leading to c-Myc upregulation. This, in turn, transcriptionally activates the splicing factor SRSF10, ultimately driving accelerated tumor growth (181). Similarly, in OC, bioinformatics profiling has linked lactylation-associated gene signatures to specific tumor subtypes and immune landscapes (156). Immunohistochemical validation has further confirmed that elevated histone lactylation serves as a robust indicator of poor prognosis in patients with OC (155).

Immune evasion constitutes a fundamental barrier in oncology. In NSCLC, elevated lactylation is associated with adverse outcomes. Mechanistically, H3K18la directly drives POM121 transcription, activating the POM121/MYC/PD-L1 signaling axis to blunt immune surveillance. Consequently, targeting this axis by combining glycolysis inhibitors with anti-PD-1 antibodies has demonstrated potent antitumor efficacy (182).

The CRC landscape reveals complex roles for lactylation in initiation, progression and therapeutic resistance (94,183). Regarding chemoresistance, SMC4 downregulation induces a ‘diapause-like’ quiescent state. This downregulation increases lactate production via glycolytic enzymes while suppressing PGAM1. The resulting increase in lactate levels drives histone lactylation to upregulate ABC transporters, thereby conferring chemoresistance (184). Furthermore, the interplay between the microbiome and non-histone lactylation is critical yet underappreciated (185,186). For example, tumor-resident ' suppresses NF-κB signaling by inducing lactylation of RIG-I. This modification drives M2 macrophage polarization and facilitates colorectal liver metastasis. Targeting this pathway with a specific RIG-I lactylation inhibitor has been shown to restore sensitivity to 5-fluorouracil (187).

In ccRCC, pathogenesis is closely tied to the inactivation of von Hippel-Lindau (VHL) (188). Loss of VHL function perturbs histone lactylation dynamics, leading to the transcriptional activation of PDGFRβ. This establishes a positive feedback loop between histone lactylation and PDGFRβ signaling, presenting a viable therapeutic target (189).

Beyond solid tumors, lactylation markedly impacts hematological malignancies. In leukemia, histone lactylation promotes progression by upregulating ALKBH3, which removes m1A methylation from SP100A and consequently destabilizes the tumor suppressor PML (190). In diffuse large B-cell lymphoma, elevated lactate levels are closely linked to prognosis, immune function and drug resistance (191). Similarly, in multiple myeloma (MM), lactylation-related genes have emerged as prognostic biomarkers (192). Addressing resistance to proteasome inhibitors in MM, research indicates that Mucin20 drives resistance by modulating the MET signaling pathway through the suppression of IGF-1R lactylation (193). Despite these advances, the field remains nascent and mechanistic landscapes await further elucidation.

Lactate serves as the primary substrate for protein lactylation and drives tumor progression through multiple molecular mechanisms. Consequently, pharmacologically intercepting the lactate axis constitutes a promising frontier in oncology (194). Current therapeutic strategies have focused extensively on blocking lactate metabolism and transport, with research directed toward LDHA/B and MCT1/4.

Regarding LDH inhibition, several potent compounds targeting LDHA have emerged. For example, ML-05 has been shown to effectively curtail cellular lactate synthesis and suppress proliferation in melanoma models (195). Furthermore, evidence suggests that LDHA inhibitors can function as valuable adjunctive agents in pancreatic cancer regimens (196). While LDHB is generally considered secondary to LDHA in tumorigenesis, it retains functional importance in modulating autophagy, apoptosis and the immune microenvironment (197,198). To date, the selective LDHB inhibitor AXKO-0046 has demonstrated competitive inhibition; however, it remains a tool for mechanistic validation in cancer metabolism rather than a clinical therapeutic (199).

AZD3965 represents a first-in-class inhibitor targeting MCT1 and MCT2 with selectivity over MCT3 and MCT4. Preclinically, it suppresses hematological tumor growth, and exhibits synergy with doxorubicin or rituximab in diffuse large B-cell and Burkitt lymphomas (200). Crucially, the 2023 publication of its Phase I trial (NCT01791595) provided pivotal clinical insights. While the drug showed a favorable safety profile, its single-agent efficacy was limited, likely due to a compensatory lactate efflux mechanism mediated by MCT4 in solid tumors. This underscores the necessity for patient stratification strategies, specifically targeting MCT4-negative tumors, or the development of combination therapies (201).

Conversely, MCT4 is essential for lactate efflux under hypoxic conditions, and its blockade can induce lethal intracellular lactate accumulation (202). In HNSCC, MCT4 inhibition has been proven to attenuate invasiveness (203). A notable advancement involves VB124, a potent MCT4 inhibitor that restricts liver tumor growth in immunocompetent models by potentiating CD8⁺ T-cell infiltration and cytotoxicity (204). These findings position VB124 as a high-priority candidate for future clinical investigation, particularly in synergistic combinations with immunotherapy.

Therapeutic recalcitrance represents a formidable barrier in oncology, profoundly undermining the clinical efficacy of antineoplastic regimens (205). Accumulating evidence implicates protein lactylation, which affects both histone and non-histone substrates, as a potent driver of this phenomenon, conferring resistance to radiotherapy and chemotherapy through multiple molecular mechanisms.

In GBM, clinical outcomes have revealed that patients with elevated ALDH1A3 expression derive minimal benefit from postoperative chemoradiation. To elucidate the molecular basis of this failure, proteomic profiling of lactate-rich GBM stem cells identified the lactylation of XRCC1 at K247 as a pivotal determinant of radio- and chemoresistance (121). Parallel investigations in GBM have further established that H3K9 histone lactylation drives temozolomide resistance. Notably, the repurposed antiepileptic agent stiripentol has been shown to effectively inhibit this lactylation event, offering a viable combinatorial strategy for GBM management (206).

In bladder cancer, where resistance to platinum-based agents is common, single-cell RNA sequencing has unveiled a strong association between cisplatin resistance and histone H3K18la (207). Similarly, for advanced prostate cancer, resistance to the androgen receptor signaling inhibitor enzalutamide poses a notable challenge. Mechanistic studies attribute this to the NF-κB/STAT3/SLC4A4 signaling axis, which facilitates p53 lactylation, thereby driving tumor progression and drug insensitivity (208,209).

In HCC, acquired resistance remains the primary limiting factor for molecular targeted therapies. In lenvatinib-resistant models, a lactylated IGF2BP3-PCK2-SAM-m6A feedback loop has been found to sustain high expression of PCK2 and NRF2; this upregulation bolsters the antioxidant defense system, thereby maintaining lenvatinib resistance (210). Furthermore, although bevacizumab is a cornerstone of CRC treatment, its efficacy is often compromised by resistance mechanisms linked to histone lactylation. Consequently, targeting histone lactylation in conjunction with bevacizumab represents a novel therapeutic option for overcoming resistance in advanced malignancies (183). For reference, detailed data regarding these treatment associations are compiled in Table II.

Despite the substantial therapeutic potential of targeting lactate metabolism and lactylation, translation of these strategies into clinical practice is currently hindered by limitations in single-agent potency and pharmacological specificity.

Monotherapies frequently fail to achieve durable responses, a failure attributed to tumor metabolic flexibility and compensatory activation of alternative transport mechanisms, exemplified by the upregulation of MCT4 following MCT1 blockade. To overcome this, combinatorial regimens have been prioritized to induce synergistic antitumor activity. A particularly promising option involves coupling glycolysis or lactate inhibitors with immunotherapeutic agents (211). Given that lactate accumulation within the TME actively dampens T-cell cytotoxicity, therapeutic depletion of lactate alleviates this immunosuppression. Indeed, empirical data have demonstrated that the concurrent administration of anti-PD-1 antibodies and LDH inhibitors yields efficacy superior to that of either agent alone (212). In NSCLC, combining glycolysis inhibitors with immune checkpoint blockade has been shown to disrupt the histone lactylation-driven POM121/MYC/PD-L1 signaling axis, effectively resensitizing resistant tumors to anti-PD-1 therapy (182).

Conversely, the development of lactylation-specific inhibitors is constrained by the risk of off-target toxicity. A notable bottleneck is the functional duality of ‘writer’ enzymes; p300, for example, functions as both a histone acetyltransferase and a lactyltransferase (85). Consequently, indiscriminate inhibition of p300 risks suppressing physiological histone acetylation, which could catastrophically disrupt essential transcriptional programs and cellular homeostasis. Future medicinal chemistry efforts must therefore prioritize the structural delineation of domains specific to lactyl-CoA binding. The goal is to uncouple lactylation inhibition from acetylation, thereby maximizing therapeutic precision while minimizing collateral toxicity. Furthermore, recent literature positions lactylation as a central epigenetic node integrating multifactorial resistance mechanisms. This suggests that targeting downstream effectors, rather than the writers themselves, may offer a strategic bypass around compensatory metabolic adaptations (213).

Currently, the identification of lactylation relies heavily on HPLC-MS/MS and isotope metabolic labeling (9). While robust for research, these methods are costly, time-consuming and impractical for routine clinical diagnosis using tissue biopsies or blood samples. Although immunohistochemistry has been used to detect lactylation in OC tissues (155), standardization of antibodies remains a challenge. Future priorities should focus on developing highly specific, lactylation-sensitive imaging agents and noninvasive liquid-biopsy biomarkers to enable real-time monitoring of lactylation dynamics in patients.

Lactylation levels exhibit notable heterogeneity not only among patients but also within the TME. For example, single-cell analyses have revealed distinct lactylation patterns in different cell subsets, such as macrophages and cancer stem cells (119,120). This heterogeneity suggests that a ‘one-size-fits-all’ metabolic therapy may fail. Consequently, the construction of patient-derived xenograft models or organoids to evaluate individual sensitivity to lactylation inhibitors is essential. Furthermore, gene signatures related to lactylation, as identified in OC (156), should be validated as predictive tools for therapeutic response. Consistent with this, recent literature posits that deciphering the specific interaction networks between lactylation and immune checkpoints is critical for advancing precision oncology (214).

A major ethical and safety concern is that lactate is not solely a tumor metabolite but a critical fuel for normal physiological functions, including cardiac modulation (13) and skeletal muscle metabolism (39). Broad-spectrum inhibition of lactate production or transport (via systemic LDH or MCT inhibition) carries a risk of severe systemic toxicity, including muscle fatigue and cardiac dysfunction. Therefore, developing drug delivery systems that specifically target the acidic TME or exploiting synthetic lethality to minimize off-target effects on healthy tissues is a prerequisite for clinical trials.