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Introduction

Despite notable advances in diagnostic techniques and therapeutic interventions, cancer remains a formidable global public health challenge (1). Tumor growth is orchestrated by a finely tuned interplay of numerous signaling molecules, culminating in the formation of highly intricate and diverse signaling networks (2). A defining hallmark of tumorigenesis lies in the dysregulation of pathways essential for maintaining homeostasis in normal cells. Elucidating the molecular mechanisms that underpin tumor initiation and progression is therefore pivotal for identifying novel therapeutic targets and broadening the scope of current oncological treatment strategies.

Post-translational modifications (PTMs) of proteins constitute a fundamental dimension of epigenetic regulation (3). PTMs involve covalent alterations to either the polypeptide backbone or side chains of proteins, and encompass a wide spectrum of biochemical modifications (4), including phosphorylation, ubiquitination, succinylation, methylation, acetylation, glycosylation and SUMOylation (5). As the ultimate executors of biological function (6), proteins derive much of their structural and functional plasticity from these modifications (7). PTMs profoundly influence protein-protein interactions, molecular stability, folding dynamics, solubility and subcellular localization (8). Aberrant PTMs often precipitate the loss of normal protein function and are implicated, either directly or indirectly, in the pathogenesis of various diseases (9). This is exemplified by NLRP3 palmitoylation, which regulates inflammasome activation and drives inflammatory bowel disease progression (10), and HRAS palmitoylation, which promotes renal fibrosis development (11).

Accumulating evidence underscores a close association between diverse PTMs and critical oncogenic processes, such as tumor initiation, metastasis and resistance to anticancer therapies (12). For instance, succinylation of the serine β-lactamase-like protein has been shown to facilitate the progression of hepatocellular carcinoma (13). Hence, a deeper understanding of PTMs may yield transformative insights into cancer prevention, early diagnosis and therapeutic innovation (14).

Most PTMs are enzymatically catalyzed and are generally orchestrated by three classes of enzymes distinguished by their functional roles: i) ‘Writers’, which introduce specific chemical moieties; ii) ‘readers’, which recognize and interpret these modifications; and iii) ‘erasers’, which remove the modifications (15). A substantial proportion of PTMs are dynamically reversible (16), endowing them with significant potential as both biomarkers and therapeutic targets in oncology (17).

Protein palmitoylation, a lipid-based PTM, has garnered increasing scholarly attention in recent years (18–21). This reversible covalent modification entails the attachment of a 16-carbon palmitoyl group to cysteine residues via thioester linkages (22). Palmitoylation modulates key attributes of protein biology, including molecular stability, membrane association, intermolecular interactions and signal transduction (23), thereby playing indispensable roles across a wide array of physiological and pathological processes. Moreover, palmitoylation influences the functional activity of both oncogenic and tumor-suppressive proteins, and exhibits distinct expression patterns across cancer types, underscoring its potential as a viable therapeutic target (24). Depending on the site of attachment, palmitoylation is classified into three types: N-palmitoylation, O-palmitoylation and S-palmitoylation (25). Among these, S-palmitoylation represents the predominant and uniquely reversible form, a feature that offers promising avenues for therapeutic exploitation (26).

The present review thus seeks to summarize the current understanding of the mechanisms governing S-palmitoylation and to elucidate its multifaceted roles in tumor progression, immune regulation and metabolic reprogramming, with the overarching goal of informing the development of novel cancer-targeted therapeutic strategies.

Regulation of protein palmitoylation

Protein palmitoylation is enzymatically mediated by a family of palmitoyl acyltransferases (PATs) (27). These enzymes are characterized by a conserved zinc finger DHHC (Asp-His-His-Cys) motif located within cysteine-rich domains (28), which defines their classification as members of the zinc finger DHHC domain-containing protein family. In mammals, this family comprises 23 identified members, designated ZDHHC1 through ZDHHC24, excluding ZDHHC10 (29).

The majority of PATs are localized to intracellular organelles such as the Golgi apparatus, endoplasmic reticulum and endosomes, although a subset is found predominantly at the plasma membrane (30). The substrates of these enzymes are primarily integral membrane proteins and peripheral membrane-associated proteins (31). Through the covalent attachment of palmitoyl groups, the hydrophobicity, conformation and functional dynamics of substrate proteins are altered, thereby enhancing their membrane affinity, subcellular trafficking and spatial localization (32).

Importantly, despite significant sequence homology among PATs, these enzymes exhibit divergent acylation capacities and substrate specificities (33). Such variability is essential for the context-dependent physiological roles that palmitoylation fulfills. Similar to numerous other PTMs, palmitoylation is a reversible lipid modification (34). The cleavage of palmitoyl-CoA from target proteins is critical for maintaining the dynamic equilibrium of palmitoylation states (35).

Depalmitoylation is catalyzed by a distinct group of enzymes, including acyl-protein thioesterases, palmitoyl-protein thioesterases and proteins containing α/β-hydrolase domains (36) (Fig. 1). These enzymes counterbalance the activity of PATs to preserve the dynamic homeostasis of protein palmitoylation. Such reversible regulation is indispensable for sustaining proteomic stability and cellular function.

Figure 1. Regulation of palmitoylation modification. Under the catalytic action of palmitoyl acyltransferases (DHHC proteins), palmitoyl-CoA is covalently transferred to the thiol group of cysteine residues on target proteins, resulting in the formation of S-palmitoylated proteins. This reversible post-translational modification can subsequently be reversed through the action of depalmitoylating enzymes, which hydrolyze the fatty acyl chains and restore the unmodified state of the protein. APT, acyl-protein thioesterase; Cys, cysteine.

S-palmitoylation plays a critical role in regulating protein trafficking and subcellular localization (37). Emerging evidence indicates that >4,000 proteins may be subject to S-palmitoylation (38). The dynamic cycle of palmitoylation and depalmitoylation can occur over short time scales, allowing proteins to be rapidly redistributed among distinct cellular membrane compartments. This reversible modulation enables proteins to fulfill context-specific physiological functions and respond flexibly to diverse cellular environments and biological demands.

Role of palmitoylation in tumorigenesis

Palmitoylation governs the membrane association and intracellular trafficking of proteins, thereby playing a pivotal role in cellular signal transduction and the modulation of protein function (39). Modifications of substrate proteins by palmitoylation can act as initiating events that either promote or suppress tumor progression. For instance, in breast cancer, palmitoylation of neurotensin receptor 1 inhibits apoptosis in malignant cells (40). Conversely, in colorectal cancer, palmitoylation of death receptor 4 enhances apoptosis, suggesting a context-dependent regulatory role of palmitoylation in tumor biology (41).

A substantial number of key oncogenes and tumor suppressors are subject to palmitoylation, underscoring its critical role in tumor initiation and progression (42). Modulating palmitoylation may thus impact diverse tumor-related biological processes. For example, abhydrolase domain containing 17A depalmitoylase, a depalmitoylating enzyme targeting Rap2b, regulates its membrane localization and thereby affects colorectal cancer cell migration and invasion (43). Similarly, palmitoylation of phosphatidylinositol 4-kinase IIα enhances its catalytic activity and subcellular localization, promoting tumor growth in murine models (44).

Dysregulated expression of palmitoylation-regulating enzymes results in aberrant palmitoylation levels, which in turn can affect tumor survival and progression (Table I) (45–54). These findings suggest that both palmitoylating and depalmitoylating enzymes, as well as their substrate proteins, may serve as promising therapeutic targets in oncology. Notably, palmitoylation exhibits divergent roles across different tumor types, indicating a dual regulatory function that warrants further mechanistic investigation. Deciphering tumor-specific palmitoylation patterns will facilitate the identification of functionally relevant palmitoylated proteins and aid in the development of novel anticancer strategies.

Table I. Palmitoylation-associated proteins in various cancer types.

Table I.

Palmitoylation-associated proteins in various cancer types.

Type of cancer	Functional protein	Effect of palmitoylation on tumor	(Refs.)
Glioma	GLUT1	Enhances glycolysis, cell proliferation and glioblastoma tumorigenesis	(45)
Melanoma	MC1R	Prevents melanomagenesis	(46)
Breast cancer	RAS	Promotes breast cancer progression	(47)
Lung cancer	EGFR	Inhibits cancer cell proliferation	(48)
Pituitary tumors	ERα	Promotes the proliferation of pituitary tumor cells	(49)
Leukemia	NRAS	Promotes leukemogenesis	(50)
Hepatocellular carcinoma	PCSK9	Induces sorafenib resistance in hepatocellular carcinoma	(51)
Pancreatic cancer	CKAP4	Promotes pancreatic cancer cell proliferation	(52)
Colorectal cancer	β-catenin	Promotes colorectal cancer progression	(53)
Ovarian cancer	Claudin-3	Promotes ovarian cancer	(54)

Therapeutic interventions targeting palmitoyl acyltransferases, depalmitoylating enzymes or specific palmitoylation sites on tumor-associated proteins may offer precise and effective treatment modalities. However, given the widespread roles of these enzymes in normal cellular physiology, potential off-target effects must be carefully considered (55). Moreover, the regulation of palmitoylation involves a complex network encompassing multiple proteins and modification sites; certain substrates may be targeted by several different DHHC enzymes (56). This intricate regulatory landscape adds to the complexity of therapeutic design and highlights the need for highly selective and context-aware interventions.

Overall, while the study of palmitoylation in tumorigenesis holds significant value, numerous critical issues remain that require further scrutiny and exploration. Current understanding of the role of palmitoylation in cancer largely stems from research focused on individual proteins or specific cancer types, which may limit the generalizability of the findings. Furthermore, this field faces substantial challenges in translating preclinical research results into effective clinical therapies. Despite the promising therapeutic potential of enzymes and substrates associated with palmitoylation as targets, the complexity of the palmitoylation network poses considerable obstacles to drug development. Additionally, static experimental models often overlook the dynamic and reversible nature of palmitoylation. The levels of palmitoylation fluctuate in response to cellular signaling cues, and traditional biochemical methods may fail to fully capture the transient interactions between proteins and cell membranes. Such dynamic regulation is crucial for understanding how palmitoylation influences cellular decision-making in the context of tumor progression.

In conclusion, while palmitoylation represents a captivating and highly promising avenue for cancer therapy, the field must address methodological limitations and deepen its understanding of the intricate mechanisms regulating this modification.

Palmitoylation in tumor immunity

Immune checkpoint inhibitors have significantly improved therapeutic outcomes in various malignancies, including lung cancer (57), hepatocellular and biliary tract cancer (58) and gastric cancer (59). Programmed cell death protein 1 (PD-1) and programmed death ligand 1 (PD-L1) are recognized as key immune checkpoint molecules (60). Upon binding of PD-1 on tumor-infiltrating lymphocytes to PD-L1 on tumor cells, T-cell receptor signaling and costimulatory pathways are disrupted, leading to T-cell dysfunction and eventual exhaustion. This, in turn, enables tumor cells to evade immune surveillance (61).

Palmitoylation modulates the function of immune checkpoint proteins through various mechanisms, such as membrane localization and membrane orientation (62), protein stability (63) and interaction networks (64), thereby influencing the activity of immune cells (42). Studies have shown that inhibiting the palmitoylation of PD-L1 enhances T cell-mediated antitumor immunity (62,65,66). For instance, reducing the constitutive overexpression of PD-L1 by eliminating its palmitoylation can attenuate T-cell immunity, thereby enhancing the efficacy of T cell-based immunotherapies (67).

In addition, the palmitoylation of MHC class I molecules affects their antigen-presenting capacity (68). Targeting the palmitoylation of PD-1 has demonstrated considerable therapeutic potential by augmenting the efficacy of anti-PD-1 immune checkpoint blockade (69).

In hepatocellular carcinoma, palmitoylation of T-cell immunoglobulin and mucin-domain containing-3 (TIM-3) at cysteine residue 296 prevents its interaction with the E3 ubiquitin ligase hydroxymethyl glutaryl-coenzyme A reductase degradation protein 1, thereby stabilizing TIM-3 and impairing antitumor immunity (63). Moreover, the palmitoylation of mitochondrial antiviral-signaling protein antagonizes its ubiquitination, enhancing its stability and bolstering antitumor immune responses (70). In colorectal cancer, targeting palmitoylation of interferon γ receptor 1 (IFNGR1) has been shown to stabilize IFNGR1 and improve T cell-mediated immunity (71).

Palmitoylation also regulates tumor immunity by modulating signaling pathways and reshaping the immune microenvironment. For instance, palmitoylated proteins on extracellular vesicles derived from acute myeloid leukemia (AML) cells activate Toll-like receptor 2/Akt/mTOR signaling, thereby promoting the differentiation of myeloid-derived suppressor cells (72). In pancreatic cancer, ZDHHC9 enhances the response to anti-PD-L1 immunotherapy by remodeling the tumor microenvironment through palmitoylation-dependent mechanisms (73).

Collectively, palmitoylation exerts a profound impact on antitumor immunity by regulating the stability of immune checkpoint proteins and modulating immune cell function. Targeting palmitoylation offers a novel strategy for cancer immunotherapy. Moreover, the combination of palmitoylation-targeting agents with immune checkpoint inhibitors presents a promising therapeutic avenue. Notably, benzosceptrin C, a natural compound, has been shown to synergize with immune checkpoint blockade, thereby potentiating antitumor immune responses (74).

Crosstalk between palmitoylation and lipid metabolism in cancer

Lipids serve fundamental biological functions in the body (75). For example, lipids serve as essential structural components of the cell membrane (76), and their critical function is as signaling mediators facilitating inter-organelle communication (77). Reprogramming of lipid metabolism is now recognized as a hallmark of cancer (78). This reprogramming can occur at various stages of lipid uptake, including synthesis, storage and mobilization (79), providing essential components for membrane biogenesis and alternative energy sources (80). Tumor cells exploit reprogrammed lipid metabolism to acquire the energy, membrane constituents and bioactive lipid molecules necessary for proliferation, survival, invasion, metastasis, modulation of the tumor microenvironment and therapeutic resistance (81). Rapid tumor cell growth is highly dependent on lipid metabolism (82). To sustain this demand, tumor cells utilize various transport proteins to mediate lipid uptake and oxidation or to activate oncogenic signaling pathways (83), thereby promoting tumor progression and shaping tumor-associated immunity. For example, upregulation of CD36 in CD8+ T cells leads to excessive lipid accumulation, impairing the secretion of antitumor cytokines such as IFN-γ and tumor necrosis factor-α, ultimately diminishing cytotoxic T-cell responses (84). In prostate cancer, exonuclease 1 has been shown to promote tumor progression by regulating lipid metabolic reprogramming via the p53/sterol regulatory element-binding protein 1 (SREBP1) axis (85). These insights highlight lipid metabolism as a promising therapeutic target in cancer (86).

Palmitic acid is derived from both endogenous synthesis and exogenous dietary intake (87). Fatty acid synthase in tumor cells catalyzes the formation of abundant C16 palmitic acid, the most prevalent saturated long-chain fatty acid (88). As a substrate for palmitoylation, fluctuations in palmitic acid levels can directly impact the availability of substrates for protein palmitoylation. During palmitoylation, palmitic acid is first converted into palmitoyl-CoA, which is then enzymatically linked to cysteine residues of target proteins, thereby modulating their biochemical properties and functional states. Metabolic conditions such as high-fat diet and insulin resistance can elevate palmitic acid levels, potentially enhancing global protein palmitoylation (89,90). For instance, the accumulation of triglycerides in endothelial cells alters the cytosolic profile of free fatty acids, which may stimulate lipid droplet formation while suppressing protein S-palmitoylation (91).

Moreover, palmitoylation itself modulates lipid metabolism through regulation of key proteins. In hepatocellular carcinoma, palmitoylation-driven ubiquitination of PHD finger protein 2 along the SREBP1c axis rewires lipid metabolism (92). Palmitoylation also facilitates fatty acid synthesis and uptake. For example, palmitoylation of CD36 promotes its translocation to the plasma membrane, enhancing fatty acid uptake (93). In colorectal cancer, the palmitoyltransferase ZDHHC6 modifies peroxisome proliferator-activated receptor γ through palmitoylation, stabilizing its structure and promoting nuclear translocation, which activates the transcription of metabolic genes and enhances fatty acid biosynthesis (94).

Palmitoylation is both dependent on and capable of influencing lipid metabolism (95). In cancer, the bidirectional crosstalk between palmitoylation and lipid metabolic pathways modulates various aspects of tumor biology through multiple regulatory mechanisms. These findings not only underscore the critical roles of lipid metabolism and palmitoylation in cancer development but also provide a theoretical foundation for identifying novel therapeutic targets.

Regulation of ion channels by palmitoylation

Ion channels are a vital class of transmembrane proteins located on the cell membrane (96). By mediating the translocation of ions across membranes, they play essential roles in maintaining membrane potential, ionic homeostasis and signal transduction, which are fundamental to a variety of physiological processes (97). Through the controlled transport of water and ions, ion channels regulate transmembrane ionic composition, organellar membrane potentials, vesicular trafficking, lipid and protein synthesis, macromolecular degradation and intracellular signaling cascades (98).

Dysregulation of ion channels is a hallmark of a number of cancer types (99). For example, voltage-dependent anion channel 2 loss elicits tumour destruction (100), while in colon carcinoma, transient receptor potential canonical 1 promotes cell proliferation through modulation of intracellular calcium signaling (101). These channels contribute to intracellular ionic homeostasis and signaling, influencing the pathophysiological features of tumors to varying degrees (102). Studies have shown that ion channels affect tumor cell proliferation, apoptosis and differentiation by modulating membrane potential, cell cycle progression, intracellular calcium concentrations, cytosolic pH and cell volume (103). For instance, G protein-coupled receptors on the plasma membrane can sense the acidic tumor microenvironment and subsequently regulate calcium signaling pathways (104). Calcium signaling itself serves as a key regulatory mechanism in various cancer types, playing crucial roles in cancer cell proliferation, migration and invasion (105). For instance, voltage-gated calcium channel Cav2.3 mutations are implicated in lung cancer (106), whereas inhibition of T-type Ca2+ channels reduces esophageal cancer cell proliferation (107), and their blockade suppresses proliferation in breast cancer cells (108). Consequently, calcium-related ion channels have emerged as promising targets for anticancer drug development (109). Moreover, inhibition of specific ion channels has been reported to enhance the efficacy of certain anticancer therapies (110). These findings underscore the therapeutic potential of targeting ion channels in oncology.

Palmitoylation, a reversible post-translational lipid modification, regulates ion channel function by modulating associated linker proteins, signaling intermediates and scaffold proteins within ion channel complexes (111). Accumulating evidence suggests that palmitoylation has a significant impact on the function of ion channels, thereby influencing tumor growth. For example, palmitoylation of stimulator of interferon genes sustains calcium homeostasis through regulation of the mitochondrial voltage-dependent anion channel, ultimately promoting the progression of renal cell carcinoma (112). Within ion channels, palmitoylation can influence membrane localization, electrophysiological properties and interactions with other proteins (113). Therefore, modulation of palmitoylation on ion channel components may provide a novel approach for developing targeted therapies against tumor-associated ion channels.

Nevertheless, the precise role of palmitoylation in regulating ion channels within the cancer context remains incompletely understood. Further studies are needed to delineate the mechanistic underpinnings of palmitoylation-mediated ion channel modulation and its downstream oncogenic consequences. Additionally, the development of palmitoylation-dependent ion channel biomarkers may facilitate personalized cancer therapies tailored to specific molecular profiles.

Palmitoylation as a therapeutic target in cancer

The palmitoylation of proteins links cellular metabolism with protein function (114). Studies have shown that palmitoylation predominantly affects protein stability (115), conformational changes (116), protein trafficking (117), protein-protein interactions (118) and the regulation of ion channel activity, thereby influencing ionic flux across cell membranes (119). These studies highlight the diverse functional impacts of palmitoylation on protein biology (Fig. 2).

Figure 2. Modification mechanism of palmitoylation on target proteins. (A) Palmitoylation regulates protein stability. (B) Palmitoylation changes the conformation of proteins. (C) Palmitoylation regulates the interoperability of proteins. (D) Palmitoylation regulates ion channel proteins to change ion flux in and out of cells. (E) Palmitoylation regulates the subcellular localization of proteins. PM, plasma membrane; ER, endoplasmic reticulum.

Understanding how palmitoylation modulates protein activity is crucial for elucidating its role in tumorigenesis, tumor progression, immune evasion and metabolic reprogramming. Although the dynamic regulation of palmitoylation by palmitoylation-related enzymes remains unclear, the pivotal role of S-palmitoylation in tumor biology emphasizes its potential as a therapeutic target. Therefore, targeting protein palmitoylation may present novel therapeutic opportunities and strategies for cancer treatment (120).

Palmitoylation is primarily regulated by enzymes associated with this modification, making targeting these enzymes a potential therapeutic strategy for tumors. Current strategies targeting palmitoylation focus on inhibiting ZDHHC enzymes, blocking palmitoylation of substrate proteins and preventing the depalmitoylation of proteins. For instance, chloroquine derivatives targeting palmitoyl-protein thioesterase 1 have been shown to inhibit tumor growth (121). Additionally, palmitoylation inhibitors have been demonstrated to reduce palmitoylation levels, thereby inhibiting the death of glioblastoma cells (122). However, a major remaining challenge is the lack of specific inhibitors for palmitoylation, as the active sites of DHHC family enzymes are highly conserved, making the development of selective competitive inhibitors difficult. As such, targeting the depalmitoylation of substrate proteins could present a more viable therapeutic approach. The broad-spectrum palmitoylation inhibitor 2-bromopalmitate is widely used to suppress the palmitoylation of substrate proteins (123), but it may also cause severe toxic side effects in normal cells. Therefore, further research is needed to develop specific palmitoylation-targeted drugs or inhibitors aimed at cancer progression.

The impact of palmitoylation on different cancer types varies, necessitating the integration of proteomics, metabolomics and other multi-omics technologies to fully elucidate the mechanisms by which palmitoylation influences distinct cancer types. Such a comprehensive analysis will provide more precise insights for targeted cancer therapies.

Future perspectives

Palmitoylation is a crucial PTM. Certain tumor-related proteins affected by palmitoylation play similar roles in various cancer types (124). For example, inhibiting the palmitoylation of EGFR suppresses both the progression of KRAS-mutant lung tumors (125) and the hepatic metastasis of colorectal cancer cells (126).

Additionally, the palmitoylation of intercellular signaling molecules plays a significant role in tumorigenesis. This suggests the potential for palmitoylation-based drug targets, and future cancer research will likely uncover more pathogenic mechanisms associated with protein palmitoylation. These findings will provide a solid theoretical foundation for the future development of palmitoylation-targeted cancer therapies. However, clinical translation of palmitoylation modulation faces several challenges. On one hand, palmitoylation can regulate tumorigenesis in both oncogenic and tumor-suppressive directions. Thus, when targeting palmitoylation, careful design of palmitoylation-targeted strategies for each specific case is necessary. On the other hand, palmitoylation enzymes may have multiple, or even overlapping, palmitoylation substrate proteins (127), and inhibiting palmitoyltransferases could impact other proteins, potentially leading to unforeseen therapeutic outcomes.

Moreover, the crosstalk between palmitoylation and other PTMs should be considered when studying protein function. For example, it has been shown that the succinylation of gasdermin D negatively regulates its palmitoylation, thereby influencing pyroptosis (128). Understanding the synergistic or antagonistic effects between palmitoylation and other PTMs will enable more precise intervention in disease-related pathways and lead to the development of more refined therapeutic strategies.

In conclusion, palmitoylation serves as an essential mechanism in regulating protein function and provides new targets and combination treatment strategies for cancer therapy. However, a deeper understanding of the role of palmitoylation in different cancer types is needed to further develop targeted therapies that specifically affect substrate proteins without impacting other proteins. Additionally, the development of more effective techniques for detecting palmitoylation modifications is crucial for uncovering its pathogenic mechanisms and facilitating the development of novel therapeutic strategies.

Acknowledgements

All figures were created with BioGDP (https://biogdp.com/?tg=CM46).

Funding

This review was funded by the Science and Technology Planning Project of Zunyi [grant nos. HZ(2022)238 and HZ(2023)270].

Availability of data and materials

Not applicable.

Authors' contributions

SH and YM conceived and designed the review, and wrote the manuscript. SC, JL, YZ and ZZ were involved in the literature search and contributed to drafting the manuscript. KZ revised and polished the manuscript. All authors have read and approved the final manuscript. Data authentication is not applicable.

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no competing interests.

References