Protein palmitoylation in cancer: molecular functions and therapeutic potential

An S-acylated N-terminus and a conserved loop regulate the activity of the ABHD17 deacylase

The dynamic addition and removal of long-chain fatty acids modulate protein function and localization. The α/β hydrolase domain-containing (ABHD) 17 enzymes remove acyl chains from membrane-localized proteins such as the oncoprotein NRas, but how the ABHD17 proteins are regulated is unknown. Here, we used cell-based studies and molecular dynamics simulations to show that ABHD17 activity is controlled by two mobile elements-an S-acylated N-terminal helix and a loop-that flank the putative substrate-binding pocket. Multiple S-acylation events anchor the N-terminal helix in the membrane, enabling hydrophobic residues in the loop to engage with the bilayer. This stabilizes the conformation of both helix and loop, alters the conformation of the binding pocket, and optimally positions the enzyme for substrate engagement. S-acylation may be a general feature of acyl-protein thioesterases. By providing a mechanistic understanding of how the lipid modification of a lipid-removing enzyme promotes its enzymatic activity, this work contributes to our understanding of cellular S-acylation cycles.

Identifying key palmitoylation-associated genes in endometriosis through genomic data analysis

BACKGROUND

Palmitoylation, a post-translational lipid modification, has garnered increasing attention for its role in inflammatory processes and tumorigenesis. Emerging evidence suggests a potential association between palmitoylation and inflammatory responses in the pathogenesis of endometriosis. However, the precise mechanistic interplay remains elusive, necessitating further investigation.

METHODS

This study integrated transcriptomic analysis and Mendelian randomization (MR) to identify a causal gene set implicated in endometriosis. Differentially expressed genes (DEGs) were first identified in the training dataset using the limma package in R. Weighted gene co-expression network analysis (WGCNA) was subsequently performed, leveraging Single Sample Gene Set Enrichment Analysis (ssGSEA)-derived scores of palmitoylation-related genes (PRGs) as phenotypic traits to identify key modular genes. The intersection of these key modular genes with DEGs yielded a refined gene set. Machine learning algorithms were then applied to further optimize gene selection, followed by external validation, immune infiltration analysis, RNA network construction, and exploration of potential targeted drug candidates.

RESULTS

Through a rigorous screening process, VRK1, GALNT12, and RMI1 emerged as key genes associated with palmitoylation, exhibiting significant downregulation in endometriosis samples (P < 0.05), indicative of a potential protective role. Immune infiltration analysis further revealed strong correlations between these genes and M2 macrophages as well as resting Natural Killer (NK) cells. Additionally, investigations into the targeted RNA network and drug association profiling provided novel insights, laying the groundwork for future high-quality validation studies.

CONCLUSIONS

This study employed a comprehensive analytical framework to identify palmitoylation-associated key genes in endometriosis. The integration of immunoinfiltration analysis, RNA network construction, and drug association profiling offers valuable insights for advancing clinical diagnostics, disease monitoring, and therapeutic development in endometriosis.

Posttranslational Modification in Bone Homeostasis and Osteoporosis

Bone is responsible for providing mechanical protection, attachment sites for muscles, hematopoiesis micssroenvironment, and maintaining balance between calcium and phosphorate. As a highly active and dynamically regulated organ, the balance between formation and resorption of bone is crucial in bone development, damaged bone repair, and mineral homeostasis, while dysregulation in bone remodeling impairs bone structure and strength, leading to deficiency in bone function and skeletal disorder, such as osteoporosis. Osteoporosis refers to compromised bone mass and higher susceptibility of fracture, resulting from several risk factors deteriorating the balanced system between osteoblast-mediated bone formation and osteoclast-mediated bone resorption. This balanced system is strictly regulated by translational modification, such as phosphorylation, methylation, acetylation, ubiquitination, sumoylation, glycosylation, ADP-ribosylation, S-palmitoylation, citrullination, and so on. This review specifically describes the updating researches concerning bone formation and bone resorption mediated by posttranslational modification. We highlight dysregulated posttranslational modification in osteoblast and osteoclast differentiation. We also emphasize involvement of posttranslational modification in osteoporosis development, so as to elucidate the underlying molecular basis of osteoporosis. Then, we point out translational potential of PTMs as therapeutic targets. This review will deepen our understanding between posttranslational modification and osteoporosis, and identify novel targets for clinical treatment and identify future directions.

Artemether relieves liver fibrosis by triggering ferroptosis in hepatic stellate cells via DHHC12-mediated S-palmitoylation of the BECN1 protein

Liver fibrosis, a pivotal stage in chronic liver disease progression, is driven by hepatic stellate cell (HSC) activation. Ferroptosis is a novel form of programmed cell death, which offers therapeutic potential for liver fibrosis. Although artemether (ART) exhibits antifibrotic properties, its mechanisms in liver fibrosis remain unclear. This study aimed to determine the therapeutic effects of ART on liver fibrosis and explore the role of S-palmitoylation in HSC ferroptosis.

METHODS

A mouse model of liver fibrosis was constructed by carbon tetrachloride (CCl4) injection. Transforming growth factor-β (TGF-β) was used for stimulating HSC activation in vitro. Histopathological and serological assays were performed to analyze the therapy effects of ART. Liquid Chromatography/Mass Spectrometry (LC/MS) and acyl-biotinyl exchange (ABE) were used to determine the role of S-palmitoylation in ART-induced HSC ferroptosis. Western blot and Co-Immunoprecipitation (Co-IP) were performed to examine the effects of autophagy in ART-induced HSC ferroptosis through regulating BECN1 S-palmitoylation.

RESULTS

ART ameliorated liver fibrosis by inducing HSC ferroptosis, and the ferroptosis inhibitor ferrostatin-1 (Fer-1) impaired the inhibitory effect of ART. Interestingly, the levels of S-palmitoylation were elevated by upregulating the palmitoyltransferase DHHC12 during ART-induced HSC ferroptosis. DHHC12 knockdown reduced S-palmitoylation levels and impaired ART-mediated HSC ferroptosis. RNA-seq analysis indicated that autophagy activation was essential for ART to induce HSC ferroptosis. 3-methyladenine (3-MA) suppressed autophagy and ART-induced HSC ferroptosis. Importantly, BECN1 S-palmitoylation by DHHC12 drove ART to activate autophagy. DHHC12 bound to the cysteine 21 residue of BECN1, thereby stabilizing the BECN1 protein and facilitating autophagy activation. Mutation of the cysteine 21 residue decreased BECN1 protein stability, autophagy activation and ferroptosis in ART-treated HSCs. In a mouse model of hepatic fibrosis, HSC-specific inhibition of BECN1 S-palmitoylation reversed ART-induced HSC ferroptosis and the improvement of fibrotic liver.

CONCLUSIONS

ART alleviates liver fibrosis by inducing HSC ferroptosis via DHHC12-mediated BECN1 protein S-palmitoylation.

Metabolites-mediated posttranslational modifications in cardiac metabolic remodeling: Implications for disease pathology and therapeutic potential

The nonenergy - producing functions of metabolism are attracting increasing attention, as metabolic changes are involved in discrete pathways modulating enzyme activity and gene expression. Substantial evidence suggests that myocardial metabolic remodeling occurring during diabetic cardiomyopathy, heart failure, and cardiac pathological stress (e.g., myocardial ischemia, pressure overload) contributes to the progression of pathology. Within the rewired metabolic network, metabolic intermediates and end-products can directly alter protein function and/or regulate epigenetic modifications by providing acyl groups for posttranslational modifications, thereby affecting the overall cardiac stress response and providing a direct link between cellular metabolism and cardiac pathology. This review provides a comprehensive overview of the functional diversity and mechanistic roles of several types of metabolite-mediated histone and nonhistone acylation, namely O-GlcNAcylation, lactylation, crotonylation, β-hydroxybutyrylation, and succinylation, as well as fatty acid-mediated modifications, in regulating physiological processes and contributing to the progression of heart disease. Furthermore, it explores the potential of these modifications as therapeutic targets for disease intervention.

ZDHHC9-mediated CD38 palmitoylation stabilizes CD38 expression and promotes pancreatic cancer growth

The cluster of differentiation 38 (CD38) is a multifunctional transmembrane protein involved in numerous physiological and pathological processes including aging, neurodegenerative diseases, and tumorigenesis, hence is an attractive drug target. However, the mechanisms underlying the regulation of CD38 expression remain enigmatic. Herein, we report for the first time that CD38 is palmitoylated at Cys16, and that S-palmitoylation is required to maintain CD38 protein expression in tumor cells. Furthermore, we identify DHHC9 as the palmitoyl transferase and APT1 as the acylprotein thioesterase responsible for this crucial post-translational modification. Finally, we designed a competitive peptide of CD38 palmitoylation that decreases CD38 expression in tumor cells and suppresses tumor progression in vivo. These findings provide novel insight into CD38 regulation and highlight potential therapeutic strategies targeting CD38 palmitoylation for cancer treatment.

Unlocking the brain's code: The crucial role of post-translational modifications in neurodevelopment and neurological function

Post-translational modifications (PTMs) represent a crucial regulatory mechanism in the brain, influencing various processes, including neurodevelopment and neurological function. This review discusses the effects of PTMs, such as phosphorylation, ubiquitination, acetylation, and glycosylation, on neurodevelopment and central nervous system functionality. Although neurodevelopmental processes linked to PTMs are complex, proteins frequently converge within shared pathways. These pathways encompass neurodevelopmental processes, signaling mechanisms, neuronal migration, and synaptic connection formation, where PTMs act as dynamic regulators, ensuring the precise execution of brain functions. A detailed investigation of the fundamental mechanisms governing these pathways will contribute to a deeper understanding of nervous system functions and facilitate the identification of potential therapeutic targets. A thorough examination of the PTM landscape holds significant potential, not only in advancing knowledge but also in developing treatments for various neurological disorders.

Dynamic PRDX S-acylation modulates ROS stress and signaling

Peroxiredoxins (PRDXs) are a highly conserved family of peroxidases that serve as the primary scavengers of peroxides. Post-translational modifications play crucial roles modulating PRDX activities, tuning the balance between reactive oxygen species (ROS) signaling and stress. We previously reported that S-acylation occurs at the "peroxidatic" cysteine (Cp) site of PRDX5 and that it inhibits PRDX5 activity. Here, we show that the PRDX family more broadly is subject to S-acylation at the Cp site of all PRDXs and that PRDX S-acylation dynamically responds to cellular ROS levels. Using activity-based fluorescent imaging with DPP-Red, a red-shifted fluorescent indicator for acyl-protein thioesterase (APT) activity, we also discover that the instigation of ROS-stress via exogenous H2O2 activates both the cytosolic and mitochondrial APTs, whereas epidermal growth factor (EGF)-stimulated endogenous H2O2 deactivates the cytosolic APTs. These results indicate that APTs help tune H2O2 signal transduction and ROS protection through PRDX S-deacylation.

DNA Methylation-Regulated ZDHHC13 Promotes the Progression of Parkinson's Disease

Recent studies suggest that palmitoylation may influence proteins involved in neurotransmission and neurodegenerative changes, such as pathological α-synuclein. However, the role of palmitoylation in Parkinson's disease (PD) has not been systematically investigated. Additionally, findings on DNA methylation changes and PD-associated gene expression remain inconsistent. This study aims to explore the causal relationship and mechanisms between palmitoylation genes, DNA methylation, and PD using Mendelian Randomization (MR). This study employed two-sample MR analysis, summary-data-based Mendelian Randomization (SMR) analysis, and mediation analysis, utilizing PD GWAS data from the Finngen database, palmitoylation genes data from the eQTLGen database, and DNA methylation data from the GoDMC database. First, a two-sample MR analysis was used to evaluate the causal relationship between the palmitoylation genes and PD. Then, the SMR method was applied to validate the association between gene expression and PD. Finally, mediation analysis was conducted to explore the mediating effect of DNA methylation on the relationship between expression of palmitoylation genes and PD. Our study found a significant positive correlation between high expression of the ZDHHC13 gene and increased PD risk. Each 1 standard deviation increase in ZDHHC13 expression was associated with a 24.20% increase in PD risk. Further DNA methylation analysis identified two key methylation sites (cg00161556 and cg27379915), which indirectly influenced the occurrence of PD by regulating the expression of the ZDHHC13 gene. Mediation effect analysis revealed that the methylation sites cg00161556 and cg27379915 indirectly promoted the development of PD by regulating the expression of the ZDHHC13 gene, with the mediation effect of ZDHHC13 gene expression accounting for 63.72% and 57.61% of the total effect, respectively. Sensitivity analysis and SMR analysis supported our findings, indicating high statistical robustness. This study highlights the role of DNA methylation in regulating ZDHHC13 during PD progression, suggesting potential clinical applications such as ZDHHC13 as a biomarker or therapeutic target for early PD diagnosis and treatment.

Regulation and Function of the cGAS-STING Pathway: Mechanisms, Post-Translational Modifications, and Therapeutic Potential in Immunotherapy

Autoimmune diseases arise when the immune system attacks healthy tissues, losing tolerance for self-tissues. Normally, the immune system recognizes and defends against pathogens like bacteria and viruses. The cGAS-STING pathway, activated by pattern-recognition receptors (PRRs), plays a key role in autoimmune responses. The cGAS protein senses pathogenic DNA and synthesizes cGAMP, which induces conformational changes in STING, activating kinases IKK and TBK1 and leading to the expression of interferon genes or inflammatory mediators. This pathway is crucial in immunotherapy, activating innate immunity, enhancing antigen presentation, modulating the tumor microenvironment, and integrating into therapeutic strategies. Modulation strategies include small molecule inhibitors, oligonucleotide therapies, protein and antibody therapies, genetic and epigenetic regulation, cytokine and metabolite modulation, and nanoscale delivery systems. Post-translational modifications (PTMs) of the cGAS-STING pathway, such as phosphorylation, acetylation, ubiquitination, methylation, palmitoylation, and glycosylation, fine-tune immune responses by regulating protein activity, stability, localization, and interactions. These modifications are interconnected and collectively influence pathway functionality. We summarize the functions of cGAS-STING and its PTMs in immune and non-immune cells across various diseases, and explore potential clinical applications.

Multiple regulatory mechanisms, functions and therapeutic potential of chaperone-mediated autophagy

Autophagy refers to the proteolytic degradation of cytoplasmic components by lysosomes, and includes three defined types: macroautophagy, chaperone-mediated autophagy (CMA), and microautophagy. Although the regulatory pathways of macroautophagy are well defined, how CMA is accurately regulated remains less understood. In recent years, emerging evidence has suggested that chaperone-mediated autophagy is regulated by multiple mechanisms at nucleic acid and protein levels. In this review, we summarized recent progress on multiple regulatory mechanisms and functions concerning CMA, as well as novel treatments targeting specific regulation sites.

Identification of prognostic biomarker of non-small cell lung cancer based on mitochondrial permeability transition-driven necrosis-related genes and determination of anti-tumor effect of ARL14

BACKGROUND

Mitochondrial permeability transition (MPT)-driven necrosis (MPTDN) is a non-apoptotic mode of cell death triggered by oxidative stress and cytosolic Ca2+ overload. Recent evidence suggests that activation of MPTND can effectively induce cancer cell death and may represent a novel therapeutic strategy for cancer. Yet, the role of MPTDN-related genes in non-small cell lung cancer (NSCLC) remains unrevealed. This study aimed to identify MPTDN-related biomarkers for predicting prognosis and guiding treatment in NSCLC.

METHODS

Gene expression profiles and clinical information of NSCLC were collected from public databases, and MPTDN-related genes were obtained from published article. Differential expressed MPTDN-related genes in NSCLC and control were screened, and molecular clusters were obtained. Based on the differentially expressed genes (DGEs) between clusters, univariate Cox and LASSO regression analyses were performed to screen biomarkers, followed by nomogram construction. Correlations between these biomarkers and immune cell infiltration, immune checkpoints, and chemotherapeutic agents were observed. Expression levels of MPTDN-related biomarkers were detected using RT-qPCR in NSCLC tissues and cells. Moreover, the biological function of ARL14 in NSLCL was verified in vitro.

RESULTS

Thirty-five differential MPTDN-related genes were identified, and two molecular clusters were obtained. Three biomarkers with prognostic values were finally screened, including ARL14, ZDHHC11B, and HLF. Among them, ARL14 was significantly upregulated in tumor samples, while ZDHHC11B and HLF were downregulated. Nomogram containing three genes exhibited predictive accuracy in 1, 3, and 5-year survival rates. Three gene were strongly associated with most immune cells, immune checkpoints, and drugs sensitivity. RT-qPCR confirmed that expression levels of three genes in tissues or cells were consistent with the results of bioinformatics analysis. Finally, ARL14 knockdown inhibited the malignant phenotype of NSCLC cells.

CONCLUSION

We first performed the comprehensive analysis of MPTDN in NSCLC and screened three NSCLC-related biomarkers as promising biomarkers. ARL14 might be a new potential target for therapy of NSCLC.

Natural products targeting RAS by multiple mechanisms and its therapeutic potential in cancer: An update since 2020

RAS proteins, as pivotal signal transduction molecules, are frequently mutated and hyperactivated in various human cancers, closely associated with tumor cell proliferation, survival, and metastasis. Despite extensive research on RAS targeted therapies, developing effective RAS inhibitors remains a significant challenge. Natural products, endowed with unique chemical structures and diverse biological activities through long-term natural selection, have emerged as a vital resource for discovering novel RAS-targeted therapeutic drugs. This review focuses on the latest advancements in targeting RAS with natural products and categorizes these natural products based on their mechanisms of action. Additionally, we discuss the challenges faced by these natural products during clinical translation, including issues related to pharmacokinetics. Strategies such as combination therapy, structural optimization, and drug delivery systems are anticipated to enhance efficacy and overcome these challenges.

A facile assay for zDHHC palmitoyl transferase activation elucidates effects of mutation and modification

At least 10% of proteins constituting the human proteome are subject to S-acylation by a long-chain fatty acid, thioesterified to a Cys thiol side chain. Fatty S-acylation (prototypically, S-palmitoylation) operates across eukaryotic phylogeny and cell type. S-palmitoylation is carried out in mammalian cells by a family of 23-24 dedicated zDHHC palmitoyl transferase enzymes, and mutation of zDHHCs is associated with a number of human pathophysiologies. Activation of the zDHHCs by auto-S-palmitoylation, the transthioesterification of the active site Cys by fatty acyl coenzyme A, is the necessary first step in zDHHC-mediated protein S-palmitoylation. Most prior in vitro assessments of zDHHC activation have utilized purified zDHHCs, a time- and effort-intensive approach, which removes zDHHCs from their native membrane environment. We describe here a facile assay for zDHHC activation in native membranes. We overexpressed hemagglutinin-tagged wild-type or mutant zDHHCs in cultured HEK293 cells and prepared a whole membrane fraction, which was incubated with fluorescent palmitoyl CoA (NBD-palmitoyl-CoA) followed by SDS-PAGE, fluorescence imaging, and Western blotting for hemagglutinin. We show by mutational analysis that, as assayed, zDHHC auto-S-palmitoylation by NBD-palmitoyl-CoA is limited to the active site Cys. Application of the assay revealed differential effects on zDHHC activation of posttranslational zDHHC modification and of zDHHC mutations associated with human disease, in particular cancer. Our assay provides a facile means of assessing zDHHC activation, and thus of differentiating the effects of zDHHC mutation and posttranslational modification on zDHHC activation versus secondary effects on zDHHC functionality including altered zDHHC interaction with substrate palmitoyl-proteins.

Dietary Palmitic Acid Drives a Palmitoyltransferase ZDHHC15-YAP Feedback Loop Promoting Tumor Metastasis

Elevated uptake of saturated fatty acid palmitic acid (PA) is associated with tumor metastasis; however, the precise mechanisms remain partially understood, hindering the development of therapy for PA-driven tumor metastasis. The Hippo-Yes-associated protein (Hippo/YAP) pathway is implicated in cancer progression. Here it is shown that a high-palm oil diet potentiates tumor metastasis in murine xenografts in part through YAP. It is found that the palmitoyltransferase ZDHHC15 is a YAP-regulated gene that forms a feedback loop with YAP. Notably, PA drives the ZDHHC15-YAP feedback loop, thus enforces YAP signaling, and hence promotes tumor metastasis in murine xenografts. In addition, it is shown that ZDHHC15 associates with Kidney and brain protein (KIBRA, also known as WW- and C2 domain-containing protein 1, WWC1), an upstream component of Hippo signaling, and mediates its palmitoylation. KIBRA palmitoylation leads to its degradation and regulates its subcellular localization and activity toward the Hippo/YAP pathway. Moreover, PA enhances KIBRA palmitoylation and degradation. It is further shown that combinatorial targeting of YAP and fatty acid synthesis exhibits augmented effects against metastasis formation in mice fed with a Palm diet. Collectively, these findings uncover a ZDHHC15-YAP feedback loop as a previously unrecognized mechanism underlying PA-promoted tumor metastasis and support targeting YAP and fatty acid synthesis as potential therapeutic targets in PA-driven tumor metastasis.

Protein palmitoylation is involved in regulating mouse sperm motility via the signals of calcium, protein tyrosine phosphorylation and reactive oxygen species

BACKGROUND

Protein palmitoylation, a critical posttranslational modification, plays an indispensable role in various cellular processes, including the regulation of protein stability, mediation of membrane fusion, facilitation of intracellular protein trafficking, and participation in cellular signaling pathways. It is also implicated in the pathogenesis of diseases, such as cancer, neurological disorders, inflammation, metabolic disorders, infections, and neurodegenerative diseases. However, its regulatory effects on sperm physiology, particularly motility, remain unclear. This study aimed to elucidate the mechanism by which protein palmitoylation governs sperm motility.

METHODS

Protein palmitoylation in situ in mouse sperm was observed using innovative click chemistry. Sperm motility and motion parameters were evaluated using a computer-assisted sperm analyzer (CASA) after treatment with 2-bromopalmitic acid (2BP), a specific inhibitor of protein palmitoylation. Protein palmitoylation levels were confirmed by the acyl-biotin exchange (ABE) method. The interplay between protein palmitoylation, protein tyrosine phosphorylation, and intracellular calcium was investigated using Western blotting, ABE method, and fluorescent probes. The regulation of reactive oxygen species was also examined using fluorescent probes.

RESULTS

Localized patterns and dynamics of protein palmitoylation in distinct sperm regions were revealed, including the midpiece, post-acrosomal region, acrosome, and head. Alterations in protein palmitoylation in sperm were observed under in vitro physiological conditions. Treatment with 2BP significantly affected sperm motility and motion parameters. The study revealed interactions between protein palmitoylation, including heat shock protein 90, and protein kinase A/protein kinase C-associated protein tyrosine phosphorylation and intracellular calcium. Additionally, protein palmitoylation was found to be involved in reactive oxygen species regulation.

CONCLUSIONS

Protein palmitoylation regulates sperm motility through calcium signaling, protein tyrosine phosphorylation, and reactive oxygen species. This study revealed the characteristics of protein palmitoylation in sperm and its role in regulating sperm motility, thereby providing novel insights into the causes of asthenozoospermia associated with sperm motility in humans.

Post-translational modifications in drug resistance

Resistance to antitumor drugs, antimicrobial drugs, and antiviral drugs severely limits treatment effectiveness and cure rate of diseases. Protein post-translational modifications (PTMs) represented by glycosylation, ubiquitination, SUMOylation, acetylation, phosphorylation, palmitoylation, and lactylation are closely related to drug resistance. PTMs are typically achieved by adding sugar chains (glycosylation), small proteins (ubiquitination), lipids (palmitoylation), or functional groups (lactylation) to amino acid residues. These covalent additions are usually the results of signaling cascades and could be reversible, with the triggering mechanisms depending on the type of modifications. PTMs are involved in antitumor drug resistance, not only as inducers of drug resistance but also as targets for reversing drug resistance. Bacteria exhibit multiple PTMs-mediated antimicrobial drug resistance. PTMs allow viral proteins and host cell proteins to form complex interaction networks, inducing complex antiviral drug resistance. This review summarizes the important roles of PTMs in drug resistance, providing new ideas for exploring drug resistance mechanisms, developing new drug targets, and guiding treatment plans.

The Role of Ayurveda in Prostate Cancer Management

Ayurveda is commonly utilized in the treatment of medical ailments but has yet to gain traction in incorporation into allopathic medicine. Prostate cancer is the most common cancer among men and presents a significant public health burden across the globe. Despite advancements in the management of advanced prostate cancer including androgen deprivation therapy and novel hormonal therapies, men may eventually develop resistance to hormonal therapy. As such, there is an urgent need for novel therapeutic options in treating this malignancy. This review examines the pre-clinical evidence for Ayurveda medicinal plants such as Withania somnifera, Glycyrrhiza spp, Momordica spp, Boswellia, and Bacopa monnieri and their potential application in managing prostate cancer. Several in-vitro and pre-clinical studies suggest potentials for these plants or their derivatives in preventing or treating prostate cancers. Despite strong evidence of efficacy of these plants to potentially improve the outcome of prostate cancer, clinical trials are required to evaluate which plants may be most efficacious and to determine effective dosing strategies, as well as the use of ayurvedic plants as standalone therapies or in combination with conventional prostate cancer treatments.

Protein palmitoylation in hepatic diseases: Functional insights and therapeutic strategies

BACKGROUND

Liver pathologies represent a spectrum of conditions ranging from fatty liver to the aggressive hepatocellular carcinoma (HCC), as well as parasitic infections, which collectively pose substantial global health challenges. S-palmitoylation (commonly referred to as palmitoylation), a post-translational modification (PTM) characterized by the covalent linkage of a 16-carbon palmitic acid (PA) chain to specific cysteine residues on target proteins, plays a pivotal role in diverse cellular functions and is intimately associated with the liver's physiological and pathological states.

AIM OF REVIEW

This study aims to elucidate how protein palmitoylation affects liver disease pathophysiology and evaluates its potential as a target for diagnostic and therapeutic interventions.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Recent studies have identified the key role of protein palmitoylation in regulating the development and progression of liver diseases. This review summarizes the intricate mechanisms by which protein palmitoylation modulates the pathophysiological processes of liver diseases and explores the potential of targeting protein palmitoylation modifications or the enzymes regulating this modification as prospective diagnostic biomarkers and therapeutic targets.

Palmitoylation-related gene expression and its prognostic value in ovarian cancer: insights into immune infiltration and therapeutic potential

BACKGROUND

Palmitoylation, a key post-translational modification, plays a significant role in ovarian cancer (OV) progression. However, the impact of palmitoylation-related genes on genomic instability, immune infiltration, and therapeutic response in OV remains poorly understood. This study aimed to investigate these factors to facilitate risk stratification and therapeutic intervention, providing insights into personalized treatment strategies.

METHODS

Data from TCGA and GEO were utilized to develop a prognostic model based on palmitoylation-related genes. Differential expression, functional enrichment, and immune infiltration analyses were performed. Immune cell composition and pathway activities in different risk groups were assessed using CIBERSORT and ssGSEA algorithms. Immunotherapy response was predicted using TIDE and SubMap, while drug sensitivity differences were evaluated using the GDSC database.

RESULTS

Univariate, LASSO, and multivariate Cox regression analyses identified palmitoylation-related genes with significant prognostic value. The prognostic model effectively stratified patients into high- and low-risk groups, demonstrating significant survival differences. Immune infiltration analysis revealed distinct immune cell compositions and functions between risk groups. Low-risk patients exhibited higher immune scores and increased expression of immune checkpoints (PD-1, CD274, CTLA4), suggesting greater response to immunotherapy. Drug sensitivity analysis identified compounds with differential efficacy between risk groups, highlighting potential targeted treatment options.

CONCLUSION

Palmitoylation-related genomic features significantly influence OV progression and the immune landscape, offering potential for improved risk stratification and informing immunotherapy strategies to enhance patient outcomes.

Advances in post-translational modifications and recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) is defined as two or more pregnancy loss, which affects approximately 1-2% of women's fertility. The etiology of RSA has not yet been fully revealed, which poses a great problem for clinical treatment. Post- translational modifications(PTMs) are chemical modifications that play a crucial role in the functional proteome. A considerable number of published studies have shown the relationship between post-translational modifications of various proteins and RSA. The study of PTMs contributes to elucidating the role of modified proteins in the pathogenesis of RSA, as well as the design of more effective diagnostic/prognostic tools and more targeted treatments. Most reviews in the field of RSA have only focused on RNA epigenomics research. The present review reports the latest research developments of PTMs related to RSA, such as glycosylation, phosphorylation, Methylation, Acetylation, Ubiquitination, etc.

Research progress on S-palmitoylation modification mediated by the ZDHHC family in glioblastoma

S-Palmitoylation has been widely noticed and studied in a variety of diseases. Increasing evidence suggests that S-palmitoylation modification also plays a key role in Glioblastoma (GBM). The zDHHC family, as an important member of S-palmitoyltransferases, has received extensive attention for its function and mechanism in GBM which is one of the most common primary malignant tumors of the brain and has an adverse prognosis. This review focuses on the zDHHC family, essential S-palmitoyltransferases, and their involvement in GBM. By summarizing recent studies on zDHHC molecules in GBM, we highlight their significance in regulating critical processes such as cell proliferation, invasion, and apoptosis. Specifically, members of zDHHC3, zDHHC4, zDHHC5 and others affect key processes such as signal transduction and phenotypic transformation in GBM cells through different pathways, which in turn influence tumorigenesis and progression. This review systematically outlines the mechanism of zDHHC family-mediated S-palmitoylation modification in GBM, emphasizes its importance in the development of this disease, and provides potential targets and strategies for the treatment of GBM. It also offers theoretical foundations and insights for future research and clinical applications.

The ZDHHC13/ZDHHC17 subfamily: From biological functions to therapeutic targets of diseases

The ZDHHC13/ZDHHC17 subfamily belongs to the zinc finger DHHC-domain containing (ZDHHC) family, including ZDHHC13 and ZDHHC17. Recent studies have shown that the ZDHHC13/ZDHHC17 subfamily is involved in various pathological and physiological processes, including S-palmitoylation, Mg2+ transport, and CALCOCO1-mediated Golgiphagy. Moreover, the ZDHHC13/ZDHHC17 subfamily plays a crucial role in the occurrence and development of many diseases, including Huntington disease (HD), osteoporosis, atopic dermatitis, diabetes, and cancer. In the present review, we describe the distribution, structure, and post-translational modifications (PTMs) of the ZDHHC13/ZDHHC17 subfamily. Moreover, we effectively summarize the biological functions and associated diseases of this subfamily. Given the pleiotropy of the ZDHHC13/ZDHHC17 subfamily, it is imperative to conduct further research on its members to comprehend the pertinent pathophysiological mechanisms and to devise tactics for managing and controlling various diseases.

Spatiotemporal control of kinases and the biomolecular tools to trace activity

The delicate balance of cell physiology is implicitly tied to the expression and activation of proteins. Post-translational modifications offer a tool to dynamically switch protein activity on and off to orchestrate a wide range of protein-protein interactions to tune signal transduction during cellular homeostasis and pathological responses. There is a growing acknowledgment that subcellular locations of kinases define the spatial network of potential scaffolds, adaptors, and substrates. These highly ordered and localized biomolecular microdomains confer a spatially distinct bias in the outcomes of kinase activity. Furthermore, they may hold essential clues to the underlying mechanisms that promote disease. Developing tools to dissect the spatiotemporal activation of kinases is critical to reveal these mechanisms and promote the development of spatially targeted kinase inhibitors. Here, we discuss the spatial regulation of kinases, the tools used to detect their activity, and their potential impact on human health.

Enhancing Gpx1 palmitoylation to inhibit angiogenesis by targeting PPT1

The significance of protein S-palmitoylation in angiogenesis has been largely overlooked, leaving various aspects unexplored. Recent identification of Gpx1 as a palmitoylated protein has generated interest in exploring its potential involvement in novel pathological mechanisms related to angiogenesis. In this study, we demonstrate that Gpx1 undergoes palmitoylation at cysteine-76 and -113, with PPT1 playing a crucial role in modulating the depalmitoylation of Gpx1. Furthermore, we find that PPT1-regulated depalmitoylation negatively impacts Gpx1 protein stability. Interestingly, inhibiting Gpx1 palmitoylation, either through expression of a non-palmitoylated Gpx1 mutant or by expressing PPT1, significantly enhances neovascular angiogenesis. Conversely, in PPT1-deficient mice, angiogenesis is notably attenuated compared to wild-type mice in an Oxygen-Induced Retinopathy (OIR) model, which mimics pathological angiogenesis. Physiologically, under hypoxic conditions, Gpx1 palmitoylation levels are drastically reduced, suggesting that increasing Gpx1 palmitoylation may have beneficial effects. Indeed, enhancing Gpx1 palmitoylation by inhibiting PPT1 with DC661 effectively suppresses retinal angiogenesis in the OIR disease model. Overall, our findings highlight the pivotal role of protein palmitoylation in angiogenesis and propose a novel mechanism whereby the PPT1-Gpx1 axis modulates angiogenesis, thereby providing a potential therapeutic strategy for targeting PPT1 to combat angiogenesis.

Palmitoylation regulates myelination by modulating the ZDHHC3-Cadm4 axis in the central nervous system

The downregulation of Cadm4 (Cell adhesion molecular 4) is a prominent feature in demyelination diseases, yet, the underlying molecular mechanism remains elusive. Here, we reveal that Cadm4 undergoes specific palmitoylation at cysteine-347 (C347), which is crucial for its stable localization on the plasma membrane (PM). Mutation of C347 to alanine (C347A), blocking palmitoylation, causes Cadm4 internalization from the PM and subsequent degradation. In vivo experiments introducing the C347A mutation (Cadm4-KI) lead to severe myelin abnormalities in the central nervous system (CNS), characterized by loss, demyelination, and hypermyelination. We further identify ZDHHC3 (Zinc finger DHHC-type palmitoyltransferase 3) as the enzyme responsible for catalyzing Cadm4 palmitoylation. Depletion of ZDHHC3 reduces Cadm4 palmitoylation and diminishes its PM localization. Remarkably, genetic deletion of ZDHHC3 results in decreased Cadm4 palmitoylation and defects in CNS myelination, phenocopying the Cadm4-KI mouse model. Consequently, altered Cadm4 palmitoylation impairs neuronal transmission and cognitive behaviors in both Cadm4-KI and ZDHHC3 knockout mice. Importantly, attenuated ZDHHC3-Cadm4 signaling significantly influences neuroinflammation in diverse demyelination diseases. Mechanistically, we demonstrate the predominant expression of Cadm4 in the oligodendrocyte lineage and its potential role in modulating cell differentiation via the WNT-β-Catenin pathway. Together, our findings propose that dysregulated ZDHHC3-Cadm4 signaling contributes to myelin abnormalities, suggesting a common pathological mechanism underlying demyelination diseases associated with neuroinflammation.

Exploring Protein S-Palmitoylation: Mechanisms, Detection, and Strategies for Inhibitor Discovery

S-palmitoylation is a reversible and dynamic process that involves the addition of long-chain fatty acids to proteins. This protein modification regulates various aspects of protein function, including subcellular localization, stability, conformation, and biomolecular interactions. The zinc finger DHHC (ZDHHC) domain-containing protein family is the main group of enzymes responsible for catalyzing protein S-palmitoylation, and 23 members have been identified in mammalian cells. Many proteins that undergo S-palmitoylation have been linked to disease pathogenesis and progression, suggesting that the development of effective inhibitors is a promising therapeutic strategy. Reducing the protein S-palmitoylation level can target either the PATs directly or their substrates. However, there are rare clinically effective S-palmitoylation inhibitors. This review aims to provide an overview of the S-palmitoylation field, including the catalytic mechanism of ZDHHC, S-palmitoylation detection methods, and the functional impact of protein S-palmitoylation. Additionally, this review focuses on current strategies for expanding the chemical toolbox to develop novel and effective inhibitors that can reduce the level of S-palmitoylation of the target protein.

ZDHHC20 Activates AKT Signaling Pathway to Promote Cell Proliferation in Hepatocellular Carcinoma

Background

Liver cancer is the sixth most common cancer worldwide, and hepatocellular carcinoma (HCC) presents one of the most challenging global health issues. ZDHHC20, a member of the ZDHHC palmitoyltransferase (ZDHHC-PAT) family, is involved in a reversible lipid modification known as palmitoylation, which contributes to the occurrence and progression of various tumors. However, the specific mechanisms underlying the involvement of ZDHHC20 in this process are unclear.

Methods

The effects of both ZDHHC20 knockdown and overexpression on hepatocellular carcinoma cell proliferation were evaluated using PCR, Western blotting, CCK-8 assay, colony formation assay, cell cycle analysis, apoptosis analysis, and EDU assay. The TCGA-LIHC dataset was analyzed bioinformatically, and the phosphorylation level of PI3K and AKT in SK-Hep1 and Huh7 cells was assessed using Western blotting. Nude mouse subcutaneous xenograft experiments were conducted to evaluate the effects of different treatment conditions on mouse tumor growth.

Results

ZDHHC20 knockdown inhibited cell proliferation and promoted apoptosis, while overexpression of ZDHHC20 promoted cell proliferation and inhibited apoptosis. Knockdown of ZDHHC20 also decreased phosphorylation of PI3K and AKT in HCC, whereas overexpression of ZDHHC20 increased phosphorylation of PI3K and AKT. The PI3K-AKT pathway inhibitors, LY294002 and MK2206, effectively inhibited the promotional effects of ZDHHC20 on the proliferation and growth of HCC.

Conclusion

High expression of ZDHHC20 promotes the proliferation and tumor growth of HCC by activating the PI3K-AKT signaling pathway. The PI3K inhibitor LY294002 and the AKT inhibitor MK2206 inhibit the promotional effects of ZDHHC20 on the proliferation of HCC and the growth of tumors.

Inhibiting S-palmitoylation arrests metastasis by relocating Rap2b from plasma membrane in colorectal cancer

Rap2b, a proto-oncogene upregulated in colorectal cancer (CRC), undergoes protein S-palmitoylation at specific C-terminus sites (C176/C177). These palmitoylation sites are crucial for Rap2b localization on the plasma membrane (PM), as mutation of C176 or C177 results in cytosolic relocation of Rap2b. Our study demonstrates that Rap2b influences cell migration and invasion in CRC cells, independent of proliferation, and this activity relies on its palmitoylation. We identify ABHD17a as the depalmitoylating enzyme for Rap2b, altering PM localization and inhibiting cell migration and invasion. EGFR/PI3K signaling regulates Rap2b palmitoylation, with PI3K phosphorylating ABHD17a to modulate its activity. These findings highlight the potential of targeting Rap2b palmitoylation as an intervention strategy. Blocking the C176/C177 sites using an interacting peptide attenuates Rap2b palmitoylation, disrupting PM localization, and suppressing CRC metastasis. This study offers insights into therapeutic approaches targeting Rap2b palmitoylation for the treatment of metastatic CRC, presenting opportunities to improve patient outcomes.

Bio-Pathological Functions of Posttranslational Modifications of Histological Biomarkers in Breast Cancer

Proteins are the most common types of biomarkers used in breast cancer (BC) theranostics and management. By definition, a biomarker must be a relevant, objective, stable, and quantifiable biomolecule or other parameter, but proteins are known to exhibit the most variate and profound structural and functional variation. Thus, the proteome is highly dynamic and permanently reshaped and readapted, according to changing microenvironments, to maintain the local cell and tissue homeostasis. It is known that protein posttranslational modifications (PTMs) can affect all aspects of protein function. In this review, we focused our analysis on the different types of PTMs of histological biomarkers in BC. Thus, we analyzed the most common PTMs, including phosphorylation, acetylation, methylation, ubiquitination, SUMOylation, neddylation, palmitoylation, myristoylation, and glycosylation/sialylation/fucosylation of transcription factors, proliferation marker Ki-67, plasma membrane proteins, and histone modifications. Most of these PTMs occur in the presence of cellular stress. We emphasized that these PTMs interfere with these biomarkers maintenance, turnover and lifespan, nuclear or subcellular localization, structure and function, stabilization or inactivation, initiation or silencing of genomic and non-genomic pathways, including transcriptional activities or signaling pathways, mitosis, proteostasis, cell-cell and cell-extracellular matrix (ECM) interactions, membrane trafficking, and PPIs. Moreover, PTMs of these biomarkers orchestrate all hallmark pathways that are dysregulated in BC, playing both pro- and/or antitumoral and context-specific roles in DNA damage, repair and genomic stability, inactivation/activation of tumor-suppressor genes and oncogenes, phenotypic plasticity, epigenetic regulation of gene expression and non-mutational reprogramming, proliferative signaling, endocytosis, cell death, dysregulated TME, invasion and metastasis, including epithelial-mesenchymal/mesenchymal-epithelial transition (EMT/MET), and resistance to therapy or reversal of multidrug therapy resistance. PTMs occur in the nucleus but also at the plasma membrane and cytoplasmic level and induce biomarker translocation with opposite effects. Analysis of protein PTMs allows for the discovery and validation of new biomarkers in BC, mainly for early diagnosis, like extracellular vesicle glycosylation, which may be considered as a potential source of circulating cancer biomarkers.

Cancer plasticity in therapy resistance: Mechanisms and novel strategies

Therapy resistance poses a significant obstacle to effective cancer treatment. Recent insights into cell plasticity as a new paradigm for understanding resistance to treatment: as cancer progresses, cancer cells experience phenotypic and molecular alterations, corporately known as cell plasticity. These alterations are caused by microenvironment factors, stochastic genetic and epigenetic changes, and/or selective pressure engendered by treatment, resulting in tumor heterogeneity and therapy resistance. Increasing evidence suggests that cancer cells display remarkable intrinsic plasticity and reversibly adapt to dynamic microenvironment conditions. Dynamic interactions between cell states and with the surrounding microenvironment form a flexible tumor ecosystem, which is able to quickly adapt to external pressure, especially treatment. Here, this review delineates the formation of cancer cell plasticity (CCP) as well as its manipulation of cancer escape from treatment. Furthermore, the intrinsic and extrinsic mechanisms driving CCP that promote the development of therapy resistance is summarized. Novel treatment strategies, e.g., inhibiting or reversing CCP is also proposed. Moreover, the review discusses the multiple lines of ongoing clinical trials globally aimed at ameliorating therapy resistance. Such advances provide directions for the development of new treatment modalities and combination therapies against CCP in the context of therapy resistance.

ZDHHC1 downregulates LIPG and inhibits colorectal cancer growth via IGF2BP1 Palmitoylation

Alteration in lipid metabolism is recognized as a hallmark feature of colorectal cancer (CRC). Protein S-palmitoylation plays a critical role in many different cellular processes including protein-lipid interaction. Zinc Finger DHHC-Type Containing 1 (ZDHHC1, also known as ZNF377) belongs to the palmitoyl-transferase ZDHHC family, and is a potential tumor suppressor. However, our knowledge of the functional roles of ZDHHC1 in CRC is limited. We discovered that ZDHHC1 expression was downregulated in CRC tissues and that low levels of ZDHHC1 were associated with unfavorable prognosis. Functional studies showed that ZDHHC1 inhibited CRC cell proliferation and invasion in vitro and in vivo. We also found that lipase G (LIPG) is negatively regulated by ZDHHC1 and plays a key role in CRC cell growth through lipid storage. Additionally, we demonstrated that ZDHHC1 functions as a IGF2BP1-palmitoylating enzyme that induces S-palmitoylation at IGF2BP1-C337, which results in downregulated LIPG expression via m6A modification. Mechanistic investigations revealed that the ZDHHC1/IGF2BP1/LIPG signaling axis is associated with inhibition of CRC cell growth. Our study uncovers the potential role of ZDHHC1 in CRC, including inhibition of CRC growth by reducing the stability of LIPG mRNA in an m6A dependent-manner by palmitoylation of IGF2BP1.

Palmitoyltransferase ZDHHC6 promotes colon tumorigenesis by targeting PPARγ-driven lipid biosynthesis via regulating lipidome metabolic reprogramming

BACKGROUND

The failure of proper recognition of the intricate nature of pathophysiology in colorectal cancer (CRC) has a substantial effect on the progress of developing novel medications and targeted therapy approaches. Imbalances in the processes of lipid oxidation and biosynthesis of fatty acids are significant risk factors for the development of CRC. Therapeutic intervention that specifically targets the peroxisome proliferator-activated receptor gamma (PPARγ) and its downstream response element, in response to lipid metabolism, has been found to promote the growth of tumors and has shown significant clinical advantages in cancer patients.

METHODS

Clinical CRC samples and extensive in vitro and in vivo experiments were carried out to determine the role of ZDHHC6 and its downstream targets via a series of biochemical assays, molecular analysis approaches and lipid metabolomics assay, etc. RESULTS: To study the effect of ZDHHC6 on the progression of CRC and identify whether ZDHHC6 is a palmitoyltransferase that regulates fatty acid synthesis, which directly palmitoylates and stabilizes PPARγ, and this stabilization in turn activates the ACLY transcription-related metabolic pathway. In this study, we demonstrate that PPARγ undergoes palmitoylation in its DNA binding domain (DBD) section. This lipid-related modification enhances the stability of PPARγ protein by preventing its destabilization. As a result, palmitoylated PPARγ inhibits its degradation induced by the lysosome and facilitates its translocation into the nucleus. In addition, we have identified zinc finger-aspartate-histidine-cysteine 6 (ZDHHC6) as a crucial controller of fatty acid biosynthesis. ZDHHC6 directly interacts with and adds palmitoyl groups to stabilize PPARγ at the Cys-313 site within the DBD domain of PPARγ. Consequently, this palmitoylation leads to an increase in the expression of ATP citrate lyase (ACLY). Furthermore, our findings reveals that ZDHHC6 actively stimulates the production of fatty acids and plays a role in the development of colorectal cancer. However, we have observed a significant reduction in the cancer-causing effects when the expression of ZDHHC6 is inhibited in in vivo trials. Significantly, in CRC, there is a strong positive correlation between the high expression of ZDHHC6 and the expression of PPARγ. Moreover, this high expression of ZDHHC6 is connected with the severity of CRC and is indicative of a poor prognosis.

CONCLUSIONS

We have discovered a mechanism in which lipid biosynthesis is controlled by ZDHHC6 and includes the signaling of PPARγ-ACLY in the advancement of CRC. This finding provides a justification for targeting lipid synthesis by blocking ZDHHC6 as a potential therapeutic approach.

Oncogenic fatty acid oxidation senses circadian disruption in sleep-deficiency-enhanced tumorigenesis

Circadian disruption predicts poor cancer prognosis, yet how circadian disruption is sensed in sleep-deficiency (SD)-enhanced tumorigenesis remains obscure. Here, we show fatty acid oxidation (FAO) as a circadian sensor relaying from clock disruption to oncogenic metabolic signal in SD-enhanced lung tumorigenesis. Both unbiased transcriptomic and metabolomic analyses reveal that FAO senses SD-induced circadian disruption, as illustrated by continuously increased palmitoyl-coenzyme A (PA-CoA) catalyzed by long-chain fatty acyl-CoA synthetase 1 (ACSL1). Mechanistically, SD-dysregulated CLOCK hypertransactivates ACSL1 to produce PA-CoA, which facilitates CLOCK-Cys194 S-palmitoylation in a ZDHHC5-dependent manner. This positive transcription-palmitoylation feedback loop prevents ubiquitin-proteasomal degradation of CLOCK, causing FAO-sensed circadian disruption to maintain SD-enhanced cancer stemness. Intriguingly, timed β-endorphin resets rhythmic Clock and Acsl1 expression to alleviate SD-enhanced tumorigenesis. Sleep quality and serum β-endorphin are negatively associated with both cancer development and CLOCK/ACSL1 expression in patients with cancer, suggesting dawn-supplemented β-endorphin as a potential chronotherapeutic strategy for SD-related cancer.

Mechanisms and functions of protein S-acylation

Over the past two decades, protein S-acylation (often referred to as S-palmitoylation) has emerged as an important regulator of vital signalling pathways. S-Acylation is a reversible post-translational modification that involves the attachment of a fatty acid to a protein. Maintenance of the equilibrium between protein S-acylation and deacylation has demonstrated profound effects on various cellular processes, including innate immunity, inflammation, glucose metabolism and fat metabolism, as well as on brain and heart function. This Review provides an overview of current understanding of S-acylation and deacylation enzymes, their spatiotemporal regulation by sophisticated multilayered mechanisms, and their influence on protein function, cellular processes and physiological pathways. Furthermore, we examine how disruptions in protein S-acylation are associated with a broad spectrum of diseases from cancer to autoinflammatory disorders and neurological conditions.

Depalmitoylation and cell physiology: APT1 as a mediator of metabolic signals

More than half of the global population is obese or overweight, especially in Western countries, and this excess adiposity disrupts normal physiology to cause chronic diseases. Diabetes, an adiposity-associated epidemic disease, affects >500 million people, and cases are projected to exceed 1 billion before 2050. Lipid excess can impact physiology through the posttranslational modification of proteins, including the reversible process of S-palmitoylation. Dynamic palmitoylation cycling requires the S-acylation of proteins by acyltransferases and the depalmitoylation of these proteins mediated in part by acyl-protein thioesterases (APTs) such as APT1. Emerging evidence points to tissue-specific roles for the depalmitoylase APT1 in maintaining homeostasis in the vasculature, pancreatic islets, and liver. These recent findings raise the possibility that APT1 substrates can be therapeutically targeted to treat the complications of metabolic diseases.

Acyltransferase zinc finger DHHC-type containing 2 aggravates gastric carcinoma growth by targeting Nrf2 signaling: A mechanism-based multicombination bionic nano-drug therapy

The significant regulatory role of palmitoylation modification in cancer-related targets has been demonstrated previously. However, the biological functions of Nrf2 in stomach cancer and whether the presence of Nrf2 palmitoylation affects gastric cancer (GC) progression and its treatment have not been reported. Several public datasets were used to look into the possible link between the amount of palmitoylated Nrf2 and the progression and its outcome of GC in patients. The palmitoylated Nrf2 levels in tumoral and peritumoral tissues from GC patients were also evaluated. Both loss-of-function and gain-of-function via transgenic experiments were performed to study the effects of palmitoylated Nrf2 on carcinogenesis and the pharmacological function of 2-bromopalmitate (2-BP) on the suppression of GC progression in vitro and in vitro. We discovered that Nrf2 was palmitoylated in the cytoplasmic domain, and this lipid posttranslational modification causes Nrf2 stabilization by inhibiting ubiquitination, delaying Nrf2 destruction via the proteasome and boosting nuclear translocation. Importantly, we also identify palmitoyltransferase zinc finger DHHC-type palmitoyltransferase 2 (DHHC2) as the primary acetyltransferase required for the palmitoylated Nrf2 and indicate that the suppression of Nrf2 palmitoylation via 2-bromopalmitate (2-BP), or the knockdown of DHHC2, promotes anti-cancer immunity in vitro and in mice model-bearing xenografts. Of note, based on the antineoplastic mechanism of 2-BP, a novel anti-tumor drug delivery system ground 2-BP and oxaliplatin (OXA) dual-loading gold nanorods (GNRs) with tumor cell membrane coating biomimetic nanoparticles (CM@GNRs-BO) was established. In situ photothermal therapy is done using near-infrared (NIR) laser irradiation to help release high-temperature-triggered drugs from the CM@GNRs-BO reservoir when needed. This is done to achieve photothermal/chemical synergistic therapy. Our findings show the influence and linkage of palmitoylated Nrf2 with tumoral and peritumoral tissues in GC patients, the underlying mechanism of palmitoylated Nrf2 in GC progression, and novel possible techniques for addressing Nrf2-associated immune evasion in cancer growth. Furthermore, the bionic nanomedicine developed by us has the characteristics of dual drugs delivery, homologous tumor targeting, and photothermal and chemical synergistic therapy, and is expected to become a potential platform for cancer treatment.

Identification of New Modulators and Inhibitors of Palmitoyl-Protein Thioesterase 1 for CLN1 Batten Disease and Cancer

Palmitoyl-protein thioesterase 1 (PPT1) is an understudied enzyme that is gaining attention due to its role in the depalmitoylation of several proteins involved in neurodegenerative diseases and cancer. PPT1 is overexpressed in several cancers, specifically cholangiocarcinoma and esophageal cancers. Inhibitors of PPT1 lead to cell death and have been shown to enhance the killing of tumor cells alongside known chemotherapeutics. PPT1 is hence a viable target for anticancer drug development. Furthermore, mutations in PPT1 cause a lysosomal storage disorder called infantile neuronal ceroid lipofuscinosis (CLN1 disease). Molecules that can inhibit, stabilize, or modulate the activity of this target are needed to address these diseases. We used PPT1 enzymatic assays to identify molecules that were subsequently tested by using differential scanning fluorimetry and microscale thermophoresis. Selected compounds were also tested in neuroblastoma cell lines. The resulting PPT1 screening data was used for building machine learning models to help select additional compounds for testing. We discovered two of the most potent PPT1 inhibitors reported to date, orlistat (IC50 178.8 nM) and palmostatin B (IC50 11.8 nM). When tested in HepG2 cells, it was found that these molecules had decreased activity, indicating that they were likely not penetrating the cells. The combination of in vitro enzymatic and biophysical assays enabled the identification of several molecules that can bind or inhibit PPT1 and may aid in the discovery of modulators or chaperones. The molecules identified could be used as a starting point for further optimization as treatments for other potential therapeutic applications outside CLN1 disease, such as cancer and neurological diseases.

AMPKα1-mediated ZDHHC8 phosphorylation promotes the palmitoylation of SLC7A11 to facilitate ferroptosis resistance in glioblastoma

The cystine/glutamate antiporter SLC7A11, as the key regulator of ferroptosis, functions to transport cystine for glutathione biosynthesis and antioxidant defense. Accumulating evidence has shown that SLC7A11 is overexpressed in multiple human cancers and promotes tumor growth and progression. However, the exact mechanism underlying this key protein remains unclear. In this study, we confirmed that SLC7A11 is S-palmitoylated in glioblastoma, and this modification is required for SLC7A11 protein stability. Moreover, we revealed that ZDHHC8, a member of the protein palmitoyl transferases (PATs), catalyzes S-palmitoylation of SLC7A11 at Cys327, thereby decreasing the ubiquitination level of SLC7A11. Furthermore, AMPKα1 directly phosphorylates ZDHHC8 at S299, strengthening the interaction between ZDHHC8 and SLC7A11, leading to SLC7A11 S-palmitoylation and deubiquitination. Functional investigations showed that ZDHHC8 knockdown impairs glioblastoma (GBM) cell survival via promoting intracellular ferroptosis events, which could be largely rescued by ectopic expression of SLC7A11. Clinically, ZDHHC8 expression positively correlates with SLC7A11 and AMPKα1 expression in clinical glioma specimens. This study underscores that ZDHHC8-mediated SLC7A11 S-palmitoylation is critical for ferroptosis resistance during GBM tumorigenesis, indicating a novel treatment strategy for GBM.

Protein S-palmitoylation is markedly inhibited by 4″-alkyl ether lipophilic derivatives of EGCG, the major green tea polyphenol: In vitro and in silico studies

S-palmitoylation is a dynamic lipid-based protein post-translational modification facilitated by a family of protein acyltransferases (PATs) commonly known as DHHC-PATs or DHHCs. It is the only lipid modification that is reversible, and this very fact uniquely qualifies it for therapeutic interventions through the development of DHHC inhibitors. Herein, we report that 4″-alkyl ether lipophilic derivatives of EGCG can effectively inhibit protein S-palmitoylation in vitro. With the help of metabolic labeling followed by copper(I)-catalyzed azide-alkyne cycloaddition Click reaction, we demonstrate that 4″-C14 EGCG and 4″-C16 EGCG markedly inhibited S-palmitoylation in various mammalian cells including HEK 293T, HeLa, and MCF-7 using both in gel fluorescence as well as confocal microscopy. Further, these EGCG derivatives were able to attenuate the S-palmitoylation to the basal level in DHHC3-overexpressed cells, suggesting that they are plausibly targeting DHHCs. Confocal microscopy data qualitatively reflected spatial and temporal distribution of S-palmitoylated proteins in different sub-cellular compartments and the inhibitory effects of 4″-C14 EGCG and 4″-C16 EGCG were clearly observed in the native cellular environment. Our findings were further substantiated by in silico analysis which revealed promising binding affinity and interactions of 4″-C14 EGCG and 4″-C16 EGCG with key amino acid residues present in the hydrophobic cleft of the DHHC20 enzyme. We also demonstrated the successful inhibition of S-palmitoylation of GAPDH by 4″-C16 EGCG. Taken together, our in vitro and in silico data strongly suggest that 4″-C14 EGCG and 4″-C16 EGCG can act as potent inhibitors for S-palmitoylation and can be employed as a complementary tool to investigate S-palmitoylation.

Benzosceptrin C induces lysosomal degradation of PD-L1 and promotes antitumor immunity by targeting DHHC3

Programmed cell death-1 (PD-1)/programmed cell death ligand-1 (PD-L1) blockade has become a mainstay of cancer immunotherapy. Targeting the PD-1/PD-L1 axis with small molecules is an attractive approach to enhance antitumor immunity. Here, we identified a natural marine product, benzosceptrin C (BC), that enhances the cytotoxicity of T cells to cancer cells by reducing the abundance of PD-L1. Furthermore, BC exerts its antitumor effect in mice bearing MC38 tumors by activating tumor-infiltrating T cell immunity. Mechanistic studies suggest that BC can prevent palmitoylation of PD-L1 by inhibiting DHHC3 enzymatic activity. Subsequently, PD-L1 is transferred from the membrane to the cytoplasm and cannot return to the membrane via recycling endosomes, triggering lysosome-mediated degradation of PD-L1. Moreover, the combination of BC and anti-CTLA4 effectively enhances antitumor T cell immunity. Our findings reveal a previously unrecognized antitumor mechanism of BC and represent an alternative immune checkpoint blockade (ICB) therapeutic strategy to enhance the efficacy of cancer immunotherapy.

Design and Evaluation of PROTACs Targeting Acyl Protein Thioesterase 1

PROTAC linker design remains mostly an empirical task. We employed the PRosettaC computational software in the design of sulfonyl-fluoride-based PROTACs targeting acyl protein thioesterase 1 (APT1). The software efficiently generated ternary complex models from empirically-designed PROTACs and suggested alkyl linkers to be the preferred type of linker to target APT1. Western blotting analysis revealed efficient degradation of APT1 and activity-based protein profiling showed remarkable selectivity of an alkyl linker-based PROTAC amongst serine hydrolases. Collectively, our data suggests that combining PRosettaC and chemoproteomics can effectively assist in triaging PROTACs for synthesis and providing early data on their potency and selectivity.

Protein S-palmitoylation modification: implications in tumor and tumor immune microenvironment

Protein S-palmitoylation is a reversible post-translational lipid modification that involves the addition of a 16-carbon palmitoyl group to a protein cysteine residue via a thioester linkage. This modification plays a crucial role in the regulation protein localization, accumulation, secretion, stability, and function. Dysregulation of protein S-palmitoylation can disrupt cellular pathways and contribute to the development of various diseases, particularly cancers. Aberrant S-palmitoylation has been extensively studied and proven to be involved in tumor initiation and growth, metastasis, and apoptosis. In addition, emerging evidence suggests that protein S-palmitoylation may also have a potential role in immune modulation. Therefore, a comprehensive understanding of the regulatory mechanisms of S-palmitoylation in tumor cells and the tumor immune microenvironment is essential to improve our understanding of this process. In this review, we summarize the recent progress of S-palmitoylation in tumors and the tumor immune microenvironment, focusing on the S-palmitoylation modification of various proteins. Furthermore, we propose new ideas for immunotherapeutic strategies through S-palmitoylation intervention.

Identification and validation of palmitoylation metabolism-related signature for liver hepatocellular carcinoma

BACKGROUND

Protein S-palmitoylation is a reversible posttranslational modification widely involved in tumor progression. Nevertheless, the function of palmitoylation metabolism in prognosis and tumor microenvironment characteristics in liver hepatocellular carcinoma (LIHC) patients is not fully understood.

METHODS

mRNA and clinical data of LIHC patients were obtained from the TCGA and ICGC databases. Consensus clustering was used to construct palmitoylation metabolism-related clusters. Univariate Cox and Lasso regression analyses were employed to establish a palmitoylation metabolism-related signature (PMS). ssGSEA was applied to evaluate the immune cell score in each LIHC sample. Functional enrichments were accessed through GO, KEGG and GSVA. Drug sensitivity data were downloaded from the GDSC database.

RESULTS

Three palmitoylation metabolism-related clusters with different prognostic and immune infiltration characteristics were constructed in LIHC. We identified PMS with distinct survival, clinical, and tumor immune microenvironment characteristics. The high PMS group had a poorer prognosis, higher infiltration of immunosuppressive cells and higher expression of immune checkpoints. ZDHHC20 exerted a tumor-promoting role in LIHC and was significantly associated with immunosuppressive cells and immunosuppressive checkpoints. Additionally, in HepG-2 and SMCC-7721 cells, si-ZDHHC20 boosted apoptosis but decreased proliferation and migration when compared to si-NC.

CONCLUSION

Our research revealed that PMS may accurately predict the prognosis and immune characteristics of LIHC patients. ZDHHC20 has significant clinical and immune relevance in LIHC and may contribute to the formulation of new targets for LIHC immunotherapy.

PPT1 Promotes Growth and Inhibits Ferroptosis of Oral Squamous Cell Carcinoma Cells

BACKGROUND

Oral squamous cell carcinoma (OSCC) is one of the most prevalent cancers with poor prognosis in the head and neck. Elucidating molecular mechanisms underlying OSCC occurrence and development is important for the therapy. Dysregulated palmitoylation-related enzymes have been reported in several cancers but OSCC.

OBJECTIVES

To explore the role of palmitoyl-protein thioesterase 1 (PPT1) in OSCC.

METHODS

Differentially expressed genes (DEGs) and related protein-protein interaction networks between normal oral epithelial and OSCC tissues were screened and constructed via different online databases. Tumor samples from 70 OSCC patients were evaluated for the relationship between PPT1 expression level and patients'clinic characteristics. The role of PPT1 in OSCC proliferation and metastasis was studied by functional experiments including MTT, colony formation, EdU incorporation and transwell assays. Lentivirus-based constructs were used to manipulate gene expression. FerroOrange probe and malondialdehyde assay were used to determine ferroptosis. Growth of OSCC cells in vivo was investigated by a xenograft mouse model.

RESULTS

A total of 555 DEGs were obtained, and topological analysis revealed that PPT1 and GPX4 might play critical roles in OSCC. Increased PPT1 expression was found to be correlated with poor prognosis of OSCC patients. PPT1 effectively promoted the proliferation, migration and invasion while inhibited the ferroptosis of OSCC cells. PPT1 affected the expression of glutathione peroxidase 4 (GPX4).

CONCLUSION

PPT1 promoted growth and inhibited ferroptosis of OSCC cells. PPT1 might be a potential target for OSCC therapy.

ZDHHC9: a promising therapeutic target for triple-negative breast cancer through immune modulation and immune checkpoint blockade resistance

BACKGROUND

Triple-negative breast cancer (TNBC) is a subtype of breast cancer with limited treatment options and poor prognosis. This study aimed to identify potential therapeutic targets based on the expression profiles of differentially expressed genes (DEGs) in TNBC.

METHODS

The Limma package was used to identify DEGs in TCGA and GEO datasets. Immunohistochemical (IHC) analysis and western blotting were used to determine the expression of ZDHHC9 in TNBC tissues. Flow cytometry assay and tissue immunofluorescence analysis were used to detect infiltration of multiple immune cells in tumor tissue at different levels of ZDHHC9 expression.

RESULTS

ZDHHC9 was identified as a key factor associated with resistance to ICB therapy through weighted gene co-expression network analysis (WGCNA) and single-cell RNA sequencing (scRNA-seq). Subsequently, immunohistochemical (IHC) analysis and western blotting verified that ZDHHC9 expression was elevated in TNBC cancer tissues and that elevated expression of ZDHHC9 was associated with the poor survival of patients with TNBC. Analysis of data from several public datasets revealed that patients with high ZDHHC9 expression had an increased proportion of Ki-67 + breast cancer cells and tended to be basal-like breast cancer. In addition, in vitro and in vivo experiments demonstrated that high expression of ZDHHC9 significantly predicted the efficacy and responsiveness of immunotherapy in TNBC.

CONCLUSION

These findings suggest that ZDHHC9 is a valuable marker for guiding the classification, diagnosis and prognosis of TNBC and developing specific targeted therapies.

Lymphoma in Border Collies: Genome-Wide Association and Pedigree Analysis

There has been considerable interest in studying cancer in dogs and its potential as a model system for humans. One area of research has been the search for genetic risk variants in canine lymphoma, which is amongst the most common canine cancers. Previous studies have focused on a limited number of breeds, but none have included Border Collies. The aims of this study were to identify relationships between Border Collie lymphoma cases through an extensive pedigree investigation and to utilise relationship information to conduct genome-wide association study (GWAS) analyses to identify risk regions associated with lymphoma. The expanded pedigree analysis included 83,000 Border Collies, with 71 identified lymphoma cases. The analysis identified affected close relatives, and a common ancestor was identified for 54 cases. For the genomic study, a GWAS was designed to incorporate lymphoma cases, putative "carriers", and controls. A case-control GWAS was also conducted as a comparison. Both analyses showed significant SNPs in regions on chromosomes 18 and 27. Putative top candidate genes from these regions included DLA-79, WNT10B, LMBR1L, KMT2D, and CCNT1.

Diverse Roles of Protein Palmitoylation in Cancer Progression, Immunity, Stemness, and Beyond

Protein S-palmitoylation, a type of post-translational modification, refers to the reversible process of attachment of a fatty acyl chain-a 16-carbon palmitate acid-to the specific cysteine residues on target proteins. By adding the lipid chain to proteins, it increases the hydrophobicity of proteins and modulates protein stability, interaction with effector proteins, subcellular localization, and membrane trafficking. Palmitoylation is catalyzed by a group of zinc finger DHHC-containing proteins (ZDHHCs), whereas depalmitoylation is catalyzed by a family of acyl-protein thioesterases. Increasing numbers of oncoproteins and tumor suppressors have been identified to be palmitoylated, and palmitoylation is essential for their functions. Understanding how palmitoylation influences the function of individual proteins, the physiological roles of palmitoylation, and how dysregulated palmitoylation leads to pathological consequences are important drivers of current research in this research field. Further, due to the critical roles in modifying functions of oncoproteins and tumor suppressors, targeting palmitoylation has been used as a candidate therapeutic strategy for cancer treatment. Here, based on recent literatures, we discuss the progress of investigating roles of palmitoylation in regulating cancer progression, immune responses against cancer, and cancer stem cell properties.

Palmitoylation of solute carriers

Post-translational modifications are an important mechanism in the regulation of protein expression, function, and degradation. Well-known post-translational modifications are phosphorylation, glycosylation, and ubiquitination. However, lipid modifications, including myristoylation, prenylation, and palmitoylation, are poorly studied. Since the early 2000s, researchers have become more interested in lipid modifications, especially palmitoylation. The number of articles in PubMed increased from about 350 between 2000 and 2005 to more than 600 annually during the past ten years. S-palmitoylation, where the 16-carbon saturated (C16:0) palmitic acid is added to free cysteine residues of proteins, is a reversible protein modification that can affect the expression, membrane localization, and function of the modified proteins. Various diseases like Huntington's and Alzheimer's disease have been linked to changes in protein palmitoylation. In humans, the addition of palmitic acid is mediated by 23 palmitoyl acyltransferases, also called DHHC proteins. The modification can be reversed by a few thioesterases or hydrolases. Numerous soluble and membrane-attached proteins are known to be palmitoylated, but among the approximately 400 solute carriers that are classified in 66 families, only 15 found in 8 families have so far been documented to be palmitoylated. Among the best-characterized transporters are the glucose transporters GLUT1 (SLC2A1) and GLUT4 (SLC2A4), the three monoamine transporters norepinephrine transporter (NET; SLC6A2), dopamine transporter (DAT; SLC6A3), and serotonin transporter (SERT; SLC6A4), and the sodium-calcium exchanger NCX1 (SLC8A1). While there is evidence from recent proteomics experiments that numerous solute carriers are palmitoylated, no details beyond the 15 transporters covered in this review are available.