Targeting succinylation-mediated metabolic reprogramming as a potential approach for cancer therapy

Cholangiocarcinoma PDHA1 succinylation suppresses macrophage antigen presentation via alpha-ketoglutaric acid accumulation

Gemcitabine combined with cisplatin is the first-line chemotherapy for advanced cholangiocarcinoma, but drug resistance remains a challenge, leading to unsatisfactory therapeutic effect. Here, we elucidate the possibility of chemotherapy regimens sensitized by inhibiting succinylation in patients with cholangiocarcinoma from the perspective of post-translational modification. Our omics analysis reveals that succinylation of PDHA1 lysine 83, a key enzyme in the tricarboxylic acid cycle, alters PDH enzyme activity, modulates metabolic flux, and leads to alpha-ketoglutaric acid accumulation in the tumor microenvironment. This process activates the OXGR1 receptor on macrophages, triggering MAPK signaling and inhibiting MHC-II antigen presentation, which promotes immune escape and tumor progression. Moreover, we show that inhibiting PDHA1 succinylation with CPI-613 enhances the efficacy of gemcitabine and cisplatin. Targeting PDHA1 succinylation may be a promising strategy to improve treatment outcomes in cholangiocarcinoma and warrants further clinical exploration.

KAT3B Promotes the Glycolysis and Malignant Progression of Lung Cancer by Mediating the Succinylation Modification of PKM2

Lysine succinyltransferase KAT3B plays a critical role in the progression of various cancers by modulating key metabolic pathways, including glycolysis. However, the function and underlying mechanism of KAT3B in glycolysis and lung cancer (LC) progression remain to be further studied. We determined mRNA expression levels of lysine succinyl-modifying enzymes through qRT-PCR. Protein expression and succinylation status of glycolysis-related proteins PKM2, LDHA, and ENO1 were analyzed via Western blot. Co-immunoprecipitation and immunofluorescence microscopy were employed to verify the interaction between KAT3B and PKM2. Bioinformatics analysis predicted succinylation sites on PKM2, which were subsequently validated through site-directed mutagenesis. The effects of KAT3B and PKM2 on LC cell malignancy and glycolysis were evaluated using CCK-8, transwell migration, glucose uptake, lactate production, ECAR, and OCR assays. A xenograft tumor model was utilized to assess the impact of KAT3B on LC tumor growth. We confirmed the augmentation of KAT3B in LC, which also was correlated with advanced TNM stages and elevated T stages of LC patients. Conversely, KAT3B knockdown suppressed the growth, metastasis, and glycolytic activity of LC cells in vitro, while also inhibiting tumor growth in vivo. KAT3B mediated succinylation at PKM2 K298, and the suppression of LC cell malignancy and glycolysis upon KAT3B downregulation was largely reversed by upregulation of PKM2. The KAT3B/PKM2 axis may be a novel target for LC therapy.

A nicotinamide metabolism-related gene signature for predicting immunotherapy response and prognosis in lung adenocarcinoma patients

Background

Nicotinamide (NAM) metabolism fulfills crucial functions in tumor progression. The present study aims to establish a NAM metabolism-correlated gene (NMRG) signature to assess the immunotherapy response and prognosis of lung adenocarcinoma (LUAD).

Methods

The training set and validation set (the GSE31210 dataset) were collected The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO), respectively. Molecular subtypes of LUAD were classified by consensus clustering. Mutation landscape of the top 20 somatic genes was visualized by maftools package. Subsequently, differential expression analysis was conducted using the limma package, and univariate, multivariate and LASSO regression analyses were performed on the screened genes to construct a risk model for LUAD. Next, the MCP-counter, TIMER and ESTIMATE algorithms were utilized to comprehensively assess the immune microenvironmental profile of LUAD patients in different risk groups. The efficacy of immunotherapy and chemotherapy drugs was evaluated by TIDE score and pRRophetic package. A nomogram was created by integrating RiskScore and clinical features. The mRNA expressions of independent prognostic NMRGs and the migration and invasion of LUAD cells were measured by carrying out cellular assays.

Results

Two subtypes (C1 and C2) of LUAD were classified, with C1 subtype showing a worse prognosis than C2. The top three genes with a high mutation frequency in C1 and C2 subtypes were TTN (45.25%), FLG (25.25%), and ZNF536 (19.8%). Four independent prognostic NMRGs (GJB3, CPA3, DKK1, KRT6A) were screened and used to construct a RiskScore model, which exhibited a strong predictive performance. High-risk group showed low immune cell infiltration, high TIDE score, and worse prognosis, and the patients in this group exhibited a high drug sensitivity to Cisplatin, Erlotinib, Paclitaxel, Saracatini, and CGP_082996. A nomogram was established with an accurate predictive and diagnostic performance. GJB3, DKK1, CPA3, and KRT6A were all high- expressed in LUAD cells, and silencing GJB3 inhibited the migration and invasion of LUAD cells.

Conclusion

A novel NMRG signature was developed, contributing to the prognostic evaluation and personalized treatment for LUAD patients.

CPT1A mediates succinylation of LDHA at K318 site promoteing metabolic reprogramming in NK/T-cell lymphoma nasal type

Carnitine palmitoyltransferase 1A (CPT1A), a succinylating enzyme, is highly expressed in various malignant tumors and promotes tumor progression. Succinylation is a posttranslational modification that has been reported in various diseases, but its role in NK/T-Cell lymphoma nasal type (ENKTL-NT) remains underexplored. In this study, bioinformatics analysis showed that glycolytic is a major metabolic pathway in ENKTL-NT as the expression of many glycolytic related kinases are increased. CPT1A probably mediates glycolytic process, as indicated by GO-enrichment analysis. Studies showed that CPT1A was upregulated in ENKTL-NT tissues, and that high CPT1A expression was associated with poor prognosis of ENKTL-NT. CPT1A promoted the proliferation, colony formation, invasion and glycolytic process of ENKTL-NT cells and suppresses apoptosis. Mechanistically, CPT1A promotes succinylation of LDHA at lysine 318 (K318), which increase the protein stability and the final protein level of LDHA. Both knockdown and mutation (K318R) of LDHA abolished the cancer-promoting effects of CPT1A in ENKTL-NT. In all, this study reveals the mechanism underlying the cancer-promoting effects of CPT1A via inducing LDHA succinylation and metabolic reprogramming in ENKTL-NT. These findings might provide potential targets for the diagnosis or therapy of ENKTL-NT.

Up-regulated succinylation modifications induce a senescence phenotype in microglia by altering mitochondrial energy metabolism

The aging of the central nervous system(CNS) is a primary contributor to neurodegenerative diseases in older individuals and significantly impacts their quality of life. Neuroinflammation, characterized by activation of microglia(MG) and release of cytokines, is closely associated with the onset of these neurodegenerative diseases. The activated status of MG is modulated by specifically programmed metabolic changes under various conditions. Succinylation, a novel post-translational modification(PTM) mainly involved in regulating mitochondrial energy metabolism pathways, remains unknown in its role in MG activation and aging. In the present study, we found that succinylation levels were significantly increased both during aging and upon lipopolysaccharide-induced(LPS-induced) MG activation undergoing metabolic reprogramming. Up-regulated succinylation induced by sirtuin 5 knockdown(Sirt5 KD) in microglial cell line BV2 resulted in significant up-regulation of aging-related genes, accompanied by impaired mitochondrial adaptability and a shift towards glycolysis as a major metabolic pathway. Furthermore, after LPS treatment, Sirt5 KD BV2 cells exhibited increased generation of reactive oxygen species(ROS), accumulation of lipid droplets, and elevated levels of lipid peroxidation. By employing immunoprecipitation, introducing point mutation to critical succinylation sites, and conducting enzyme activity assays for succinate dehydrogenase(SDH) and trifunctional enzyme subunit alpha(ECHA), we demonstrated that succinylation plays a regulatory role in modulating the activities of these mitochondrial enzymes. Finally, down-regulation the succinylation levels achieved through administration of succinyl phosphonate(SP) led to amelioration of MG senescence in vitro and neuroinflammation in vivo. To our knowledge, our data provide preliminary evidence indicating that up-regulated succinylation modifications elicit a senescence phenotype in MG through alterations in energy metabolism. Moreover, these findings suggest that manipulation of succinylation levels may offer valuable insights into the treatment of aging-related neuroinflammation.

Sirtuin 5-Mediated Desuccinylation of ALDH2 Alleviates Mitochondrial Oxidative Stress Following Acetaminophen-Induced Acute Liver Injury

Acetaminophen (APAP) overdose is a major cause of drug-induced liver injury. Sirtuins 5 (SIRT5) has been implicated in the development of various liver diseases. However, its involvement in APAP-induced acute liver injury (AILI) remains unclear. The present study aimed to explore the role of SIRT5 in AILI. SIRT5 expression is dramatically downregulated by APAP administration in mouse livers and AML12 hepatocytes. SIRT5 deficiency not only exacerbates liver injury and the inflammatory response, but also worsens mitochondrial oxidative stress. Conversely, the opposite pathological and biochemical changes are observed in mice with SIRT5 overexpression. Mechanistically, quantitative succinylome analysis and site mutation experiments revealed that SIRT5 desuccinylated aldehyde dehydrogenase 2 (ALDH2) at lysine 385 and maintained the enzymatic activity of ALDH2, resulting in the suppression of inflammation and mitochondrial oxidative stress. Furthermore, succinylation of ALDH2 at lysine 385 abolished its protective effect against AILI, and the protective effect of SIRT5 against AILI is dependent on the desuccinylation of ALDH2 at K385. Finally, virtual screening of natural compounds revealed that Puerarin promoted SIRT5 desuccinylase activity and further attenuated AILI. Collectively, the present study showed that the SIRT5-ALDH2 axis plays a critical role in AILI progression and might be a strategy for therapeutic intervention.

Sirtuin 5 (SIRT5) Suppresses Tumor Growth by Regulating Mitochondrial Metabolism and Synaptic Remodeling in Gliomas

Sirtuin 5 (SIRT5) is increasingly recognized as a key regulator of cellular metabolism, which is commonly dysregulated in cancer cells, resulting in enhanced proliferation and tumor progression. To investigate the clinicopathologic implications of SIRT5 dysregulation in glioblastoma, we performed comprehensive analyses of transcriptomic data and functional verifications using in vitro and in vivo glioblastoma models. We found that higher SIRT5 expression levels were associated with a favorable prognosis in glioma patients. Knockdown of SIRT5 significantly enhanced glioblastoma cell growth. Our data suggest its potential role in regulating mitochondrial metabolism in gliomas. Furthermore, SIRT5 is also significantly correlated with synaptic remodeling pathways. Our findings indicate a tumor-suppressive role for SIRT5 that extends beyond regulating cancer metabolism, by which it may function through modulating neuroplasticity. Understanding these cellular interactions provides nuanced insights into the multifaceted role of SIRT5 and the broader therapeutic implications of this for the development of novel treatment strategies.

Emerging mechanisms and promising approaches in pancreatic cancer metabolism

Pancreatic cancer is an aggressive cancer with a poor prognosis. Metabolic abnormalities are one of the hallmarks of pancreatic cancer, and pancreatic cancer cells can adapt to biosynthesis, energy intake, and redox needs through metabolic reprogramming to tolerate nutrient deficiency and hypoxic microenvironments. Pancreatic cancer cells can use glucose, amino acids, and lipids as energy to maintain malignant growth. Moreover, they also metabolically interact with cells in the tumour microenvironment to change cell fate, promote tumour progression, and even affect immune responses. Importantly, metabolic changes at the body level deserve more attention. Basic research and clinical trials based on targeted metabolic therapy or in combination with other treatments are in full swing. A more comprehensive and in-depth understanding of the metabolic regulation of pancreatic cancer cells will not only enrich the understanding of the mechanisms of disease progression but also provide inspiration for new diagnostic and therapeutic approaches.

Comprehensive review of histone lactylation: Structure, function, and therapeutic targets

Histone lysine lactylation (Kla) has emerged as a distinct epigenetic modification that differs markedly from established acylation modifications through the unique addition of a lactyl group to a lysine residue. Such modifications not only alter nucleosome structure but also significantly impact chromatin dynamics and gene expression, thus playing a crucial role in cellular metabolism, inflammatory responses, and embryonic development. The association of histone Kla with various metabolic processes, particularly glycolysis and glutamine metabolism, underscores its pivotal role in metabolic reprogramming, including in cancerous tissues, where it contributes to tumorigenesis, immune evasion, and angiogenesis. In addition, histone Kla is involved in the pathogenesis of various diseases, particularly several cancers and neurodegenerative diseases. The identification of histone Kla opens new avenues for therapeutic interventions targeting specific Kla sites. In this review, we summarize the differences between histone Kla modifications and other acylation modifications, discuss the mechanisms and roles of histone Kla in disease, and conclude by describing existing drugs and potential targets. This study provides new insights into the mechanisms linking histone Kla to diseases and into the discovery of new drugs and targets.

SIRT7 Inhibits Melanin Synthesis of PIG1 and PIG3V by Suppressing the Succinylation of EZR

Background

Vitiligo is an autoimmune disease characterized by loss of skin pigmentation and currently has no effective treatment. This study aimed to investigate the function of SIRT7, being an important desuccinylase mediating multiple disease progression, and its mechanism in vitiligo progression.

Methods

Normal human melanocytes (NHM) PIG1 and vitiligo human melanocytes (VHM) PIG3V were utilized in this research. The role of sirtuin 7 (SIRT7) and Ezrin (EZR) on melanin synthesis was investigated by detecting tyrosinase activity, melanin content, α-MSH levels, and the protein levels of melanin-related markers. The function of EZR was identified via rescue experiments, while the underlying mechanism was investigated via bioinformatic analysis, co-immunoprecipitation (co-IP), immunoprecipitation (IP), and Western blot techniques.

Results

Results showed that only SIRT7 was highly expressed in vitiligo human melanocytes, where knockingdown SIRT7 translated into increased melanin synthesis in melanocytes. Mechanistically, SIRT7 knockdown promoted the succinylation of EZR at the Lys (K)60 site. Moreover, overexpressing EZR induced higher melanin synthesis in melanocytes, while its knocking down exerted the opposite effect by inhibiting SIRT7 knockdown-induced melanin synthesis.

Conclusion

SIRT7 inhibited melanin synthesis in melanocytes by suppressing the succinylation of EZR. These findings are envisaged to provide a novel theoretical basis for vitiligo treatment.

Role of succinylation modification in central nervous system diseases

Diseases of the central nervous system (CNS), including stroke, brain tumors, and neurodegenerative diseases, have a serious impact on human health worldwide, especially in elderly patients. The brain, which is one of the body's most metabolically dynamic organs, lacks fuel stores and therefore requires a continuous supply of energy substrates. Metabolic abnormalities are closely associated with the pathogenesis of CNS disorders. Post-translational modifications (PTMs) are essential regulatory mechanisms that affect the functions of almost all proteins. Succinylation, a broad-spectrum dynamic PTM, primarily occurs in mitochondria and plays a crucial regulatory role in various diseases. In addition to directly affecting various metabolic cycle pathways, succinylation serves as an efficient and rapid biological regulatory mechanism that establishes a connection between metabolism and proteins, thereby influencing cellular functions in CNS diseases. This review offers a comprehensive analysis of succinylation and its implications in the pathological mechanisms of CNS diseases. The objective is to outline novel strategies and targets for the prevention and treatment of CNS conditions.