USP22 regulates lipidome accumulation by stabilizing PPARγ in hepatocellular carcinoma

Mechanisms and therapeutic strategies for NLRP3 degradation via post-translational modifications in ubiquitin-proteasome and autophagy lysosomal pathway

The NLRP3 inflammasome is crucial for immune responses. However, its overactivation can lead to severe inflammatory diseases, underscoring its importance as a target for therapeutic intervention. Although numerous inhibitors targeting NLRP3 exist, regulating its degradation offers an alternative and promising strategy to suppress its activation. The degradation of NLRP3 is primarily mediated by the proteasomal and autophagic pathways. The review not only elaborates on the traditional concepts of ubiquitination and NLRP3 degradation but also investigates the important roles of indirect regulatory modifications, such as phosphorylation, acetylation, ubiquitin-like modifications, and palmitoylation-key post-translational modifications (PTMs) that influence NLRP3 degradation. Additionally, we also discuss the potential targets that may affect NLRP3 degradation during the proteasomal and autophagic pathways. By unraveling these complex regulatory mechanisms, the review aims to enhance the understanding of NLRP3 regulation and its implications for developing therapeutic strategies to combat inflammatory diseases.

The deubiquitinase USP28 maintains the expression of PPARγ and its inactivation protects mice from diet-induced MASH and hepatocarcinoma

Metabolic dysfunction-associated steatohepatitis (MASH), a progressive form of metabolic dysfunction-associated fatty liver disease (MAFLD), is a leading cause of liver disease worldwide and can progress to cirrhosis and cancer. Despite its prevalence, the pathogenesis of MASH remains poorly understood, and there is only one U.S. Food and Drug Administration-approved treatment, highlighting the need for new therapeutic strategies. Peroxisome proliferator-activated receptor (PPAR)γ is activated in the liver under high-fat or obese conditions, promoting lipid storage and contributing to MASH progression. We found that USP28 expression is elevated in the livers of MAFLD/MASH patients. Through dietary induction, including a methionine-choline deficient (MCD) diet and a western diet (WD) combined with carbon tetrachloride (CCl4) injections, we established two severe mouse models of MASH to explore the role of USP28. Mechanistically, the hepatic deubiquitinase (DUB) USP28 directly binds to PPARγ, preventing its ubiquitination and subsequent degradation, thereby maintaining the integrity of the PPARγ signaling pathway. In the absence of Usp28 or if the DUB is inhibited, PPARγ is downregulated, and the PPAR signaling pathway is inhibited, enhancing cellular defenses against excess fat. Both genetic and pharmacological inactivation of Usp28 significantly reduced MASH severity induced by the MCD diet or WD-CCl4 regimen, as well as WD-CCl4-induced hepatocellular carcinoma in mice.

Prognostic Model Construction of Disulfidptosis-Related Genes and Targeted Anticancer Drug Research in Pancreatic Cancer

Pancreatic cancer stands as one of the most lethal malignancies, characterized by delayed diagnosis, high mortality rates, limited treatment efficacy, and poor prognosis. Disulfidptosis, a recently unveiled modality of cell demise induced by disulfide stress, has emerged as a critical player intricately associated with the onset and progression of various cancer types. It has emerged as a promising candidate biomarker for cancer diagnosis, prognosis assessment, and treatment strategies. In this study, we have effectively established a prognostic risk model for pancreatic cancer by incorporating multiple differentially expressed long non-coding RNAs (DElncRNAs) closely linked to disulfide-driven cell death. Our investigation delved into the nuanced relationship between the DElncRNA-based predictive model for disulfide-driven cell death and the therapeutic responses to anticancer agents. Our findings illuminate that the high-risk subgroup exhibits heightened susceptibility to the small molecule compound AZD1208, positioning it as a prospective therapeutic agent for pancreatic cancer. Finally, we have elucidated the underlying mechanistic potential of AZD1208 in ameliorating pancreatic cancer through its targeted inhibition of the peroxisome proliferator-activated receptor-γ (PPARG) protein, employing an array of comprehensive analytical methods, including molecular docking and molecular dynamics (MD) simulations. This study explores disulfidptosis-related genes, paving the way for the development of targeted therapies for pancreatic cancer and emphasizing their significance in the field of oncology. Furthermore, through computational biology approaches, the drug AZD1208 was identified as a potential treatment targeting the PPARG protein for pancreatic cancer. This discovery opens new avenues for exploring targets and screening drugs for pancreatic cancer.

USP22 promotes angiotensin II-induced podocyte injury by deubiquitinating and stabilizing HMGB1

BACKGROUND

Chronic kidney disease (CKD) remains a significant global health burden, with hypertensive nephropathy (HN) as one of its primary causes. Podocyte injury is a key factor in the progression of CKD. However, the molecular mechanisms underlying angiotensin II-induced podocyte injury remain incompletely understood. Ubiquitin-specific protease 22 (USP22) has been reported to facilitate a range of cellular processes, including cell proliferation and apoptosis. However, the role of USP22 in HN pathogenesis is unclear.

METHODS

The expression of USP22 was assessed in kidney samples from hypertensive nephropathy patients, angiotensin II-induced hypertensive nephropathy mouse models, and cultured podocytes treated with angiotensin II. Podocyte-specific USP22 knockout mice were used to investigate the effects of USP22 deletion on podocyte injury and inflammation.

RESULTS

USP22 expression was significantly upregulated in kidneys of HN patients, angiotensin II-induced mouse models, and cultured podocytes. Podocyte-specific deletion of USP22 markedly reduced angiotensin II-induced podocyte injury and inflammatory responses. Furthermore, we identified high-mobility group box protein 1 (HMGB1) as a protein that interacts with USP22. USP22 deubiquitinated and stabilized HMGB1 through K48-linked ubiquitination. Downregulation of USP22 expression improved kidney function and pathological changes in HN by promoting HMGB1 degradation.

CONCLUSION

This study identifies USP22 as a key regulator of angiotensin II-induced podocyte injury and inflammation through its interaction with HMGB1. Our findings revealed that following glomerular injury, damage and shedding of tubular cells also occurred. Targeting the USP22-HMGB1 axis offers a promising therapeutic strategy for treating hypertensive nephropathy and other types of CKD.

eIF3f promotes tumour malignancy by remodelling fatty acid biosynthesis in hepatocellular carcinoma

BACKGROUND & AIMS

Fatty acid metabolism is closely associated with hepatocellular carcinoma (HCC). Elucidating the molecules that influence fatty acid metabolism in HCC is important for developing precise therapy. However, elucidating its molecular mechanisms in tumour cells is challenging. In this study, we aimed to determine the characteristics and differences of fatty acid metabolism in HCC.

METHODS

We employed organoid models, single-cell RNA sequencing, and spatial transcriptomics to identify key genes involved in tumour fatty acid metabolism. Metabolomics, proteomics, metabolic flux analysis, and transmission electron microscopy were utilized to evaluate this metabolic process. Tumour malignancy was characterized using multi-species models. Changes in the immune microenvironment were analyzed by time-of-flight mass cytometry and multiplexed immunohistochemistry. Gene knockdown targeting the liver was achieved using lipid nanoparticles.

RESULTS

Eukaryotic translation initiation factor 3 subunit f (eIF3f) is upregulated in HCC tissues and is associated with poor prognosis. eIF3f directly interacted with and stabilised long chain acyl CoA synthetase 4 (ACSL4) through K48-linked deubiquitination, promoting fatty acid biosynthesis (FAB) and tumour malignancy. The increased fatty acid levels in the tumour microenvironment indirectly reduced CD8+ T-cell infiltration. In addition, phosphorylated eIF3f enhanced the interaction between eIF3f and ACSL4.

CONCLUSIONS

Targeting the eIF3f-ACSL4-FAB axis could decelerate HCC malignancy and enhance anti-programmed cell death-1 efficacy, suggesting that eIF3f is a potential target for precision therapy in HCC.

Ubiquitin-specific protease: an emerging key player in cardiomyopathy

Protein quality control (PQC) plays a vital role in maintaining normal heart function, as cardiomyocytes are relatively sensitive to misfolded or damaged proteins, which tend to accumulate under pathological conditions. Ubiquitin-specific protease (USP) is the largest deubiquitinating enzyme family and a key component of the ubiquitin proteasome system (UPS), which is a non-lysosomal protein degradation machinery to mediate PQC in cells. USPs regulate the stability or activity of the target proteins that involve intracellular signaling, transcriptional control of inflammation, antioxidation, and cell growth. Recent studies demonstrate that the USPs can regulate fibrosis, lipid metabolism, glucose homeostasis, hypertrophic response, post-ischemic recovery and cell death such as apoptosis and ferroptosis in cardiomyocytes. Since myocardial cell loss is an important component of cardiomyopathy, therefore, these findings suggest that the UPSs play emerging roles in cardiomyopathy. This review briefly summarizes recent literature on the regulatory roles of USPs in the occurrence and development of cardiomyopathy, giving us new insights into the molecular mechanisms of USPs in different cardiomyopathy and potential preventive strategies for cardiomyopathy.

FGF2 Mediated USP42-PPARγ Axis Activation Ameliorates Liver Oxidative Damage and Promotes Regeneration

Liver regeneration is critical for maintaining whole-body homeostasis, especially under exposure to deadly chemical toxins. Understanding the molecular mechanisms underlying liver repair is critical for the development of intervention strategies to treat liver diseases. In this study, ubiquitin-specific Proteases 42 (USP42) is identified as a novel deubiquitinases (DUB) of peroxisome proliferators-activated receptor γ (PPARγ) in hepatocytes. This DUB interacted, deubiquitinated, and stabilized PPARγ, and increased PPARγ targeted proliferative and antioxidative gene expressions, which protects the liver from carbon tetrachloride (CCL4) induced oxidative injury and promotes liver regeneration. In addition, fibroblast growth factor 2 (FGF2) initiated USP42 expression and enhanced the interaction between USP42 and PPARγ during the liver regeneration process. Moreover, the PPARγ full agonist, rosiglitazone (RSG), possesses the ability to further reinforce the USP42-PPARγ interplay, which enlightens to construct of an extracellular vesicle-based targeting strategy to activate the liver USP42-PPARγ axis and promote liver regeneration. In summary, the work uncovers the importance of USP42-PPARγ axis-mediated liver tissue homeostasis and provides a promising regimen to target this protein-protein interplay for liver regeneration.

USP43 drives cervical carcinoma progression through regulation of the Hippo/TAZ pathway

BACKGROUND

Cervical carcinoma (CC) poses significant health challenges, with its pathogenesis not fully understood. While ubiquitin specific peptidase 43 (USP43) is implicated in various cancers, its role in CC and regulation of the Hippo/Transcriptional Co-Activator With PDZ-Binding Motif (TAZ) pathway remain unexplored. This study examines USP43's impact on CC progression and its interaction with TAZ.

METHODS

USP43 expression levels in CC tissues and cell lines were assessed using reverse transcription real-time polymerase chain reaction (RT-qPCR) and Western blot. The effects of USP43 silencing on cell proliferation, migration, and invasion were evaluated through cell counting Kit-8 (CCK-8), 5-ethynyl-2'deoxyuridine (EdU), colony formation, and transwell assays. Immunofluorescence staining and co-immunoprecipitation (Co-IP) assays were used to explore the interaction between USP43 and TAZ. Polyubiquitination assays were performed to evaluate ubiquitination and stability of TAZ, and cycloheximide (CHX) chase experiments determined the half-life of TAZ. In vivo studies using BALB/c nude mice examined the impact of USP43 knockdown on tumor growth and metastasis.

RESULTS

USP43 was overexpressed in CC tissues and cell lines. Silencing of USP43 reduced cell proliferation, migration, invasion, and the epithelial-mesenchymal transition (EMT) process. Co-IP and ubiquitination assays revealed that USP43 interacted with and stabilized TAZ by inhibiting TAZ ubiquitination. CHX chase experiments confirmed that USP43 prolonged TAZ protein stability. In vivo, USP43 knockdown led to reduced tumor growth and lung metastasis. Overexpression of TAZ reversed the inhibitory effects of USP43 silencing on CC cell proliferation, migration, invasion and EMT CONCLUSION: USP43 promotes CC cell proliferation, migration, invasion, and epithelial-to-mesenchymal transition (EMT) by activating the Hippo/TAZ pathway. These findings enhance our understanding of USP43's role in CC progression and highlight potential therapeutic targets for the treatment of CC.

HACD2 Promotes Pancreatic Cancer Progression by Enhancing PKM2 Dissociation From PRKN in a Dehydratase-Independent Manner

3-Hydroxyacyl-CoA dehydratase 2 (HACD2), an obesity-related gene involved in the elongation of long-chain fatty acids, is highly expressed in pancreatic cancer (PC) and is associated with patient prognosis. Interestingly, the study reveals that HACD2 mediated the proliferation of PC cells in a dehydratase-independent manner, affecting the downstream glycolytic pathway. Mechanistically, HACD2 promotes PC cells proliferation by binding to E3 ubiquitin-protein ligase parkin (PRKN) and enhancing pyruvate kinase PKM (PKM2) dissociation from PRKN, resulting in reduced ubiquitination of PKM2 and increased dimerization of PKM2, which subsequently promote c-Myc expression and tumor growth. Moreover, HACD2 overexpression-induced PC growth is mitigated by knockdown of PKM2 or overexpression of PRKN. Furthermore, the weight loss drug orlistat, which potentially binds to HACD2, disrupted the interaction between HACD2 and PRKN and further increased the ubiquitination of PKM2. Therefore, this study elucidates the mechanism by which the obesity-related gene HACD2 regulates PC cells proliferation through a noncanonical signaling pathway, which may provide a potential new target and strategy for the individualized clinical treatment of PC.

Fatty acid binding protein 4 regulates doxorubicin-induced renal injury via mediating lipid metabolism and apoptosis

Doxorubicin(DOX) is an anthracycline chemotherapeutic drug used in the treatment of a wide range of tumors. However, the nephrotoxicity has limited the clinical application of DOX. Fatty acid-binding protein 4 (FABP4), a key adipokine mainly expressed in adipocytes, is strongly associated with kidney dysfunction and kidney disease. This study aims to investigate the role of FABP4 in DOX-induced nephrotoxicity. In vivo experiments, the mice were divided into 4 groups randomly: CON group, DOX group, 4T1 group, and 4T1 + DOX group respectively. DOX was given by intraperitoneal injection at a dose of 15 mg/kg. The kidney function indicators, the morphology and lipid deposition in renal tissues and the preliminary mechanism were assessed. In vitro experiment, HK-2 cell was used to detect DOX-induced kidney cell injury with or without BMS309403. DOX caused renal dysfunction in both DOX group and 4T1 + DOX group, with a more severe kidney injury in DOX group. DOX also induced kidney lipid deposition, glycerophospholipids metabolism dysfunction, apoptosis accompanied by increased FABP4 and decreased Peroxisome Proliferator Activated Receptor- γ (PPAR-γ) levels in the kidney tissues. The decreased cell viability, increased apoptotic ratio, elevated protein levels of apoptosis and the lipid deposition caused by DOX were all alleviated by BMS309403. FABP4 mediated DOX induced kidney damage in normal mice and tumor-bearing mice by lipid metabolism disorders and cell apoptosis. This study may enhance the clinical management of DOX-induced kidney injury and provide new therapeutic targets and preventive strategies for the clinical application of DOX.

Mitochondrial alterations and signatures in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer worldwide. Its primary risk factors are chronic liver diseases such as metabolic fatty liver disease, non-alcoholic steatohepatitis, and hepatitis B and C viral infections. These conditions contribute to a specific microenvironment in liver tumors which affects mitochondrial function. Mitochondria are energy producers in cells and are responsible for maintaining normal functions by controlling mitochondrial redox homeostasis, metabolism, bioenergetics, and cell death pathways. HCC involves abnormal mitochondrial functions, such as accumulation of reactive oxygen species, oxidative stress, hypoxia, impairment of the mitochondrial unfolded protein response, irregularities in mitochondrial dynamic fusion/fission mechanisms, and mitophagy. Cell death mechanisms, such as necroptosis, pyroptosis, ferroptosis, and cuproptosis, contribute to hepatocarcinogenesis and play a significant role in chemoresistance. The relationship between mitochondrial dynamics and HCC is thus noteworthy. In this review, we summarize the recent advances in mitochondrial alterations and signatures in HCC and attempt to elucidate its molecular biology. Here, we provide an overview of the mitochondrial processes involved in hepatocarcinogenesis and offer new insights into the molecular pathology of the disease. This may help guide future research focused on improving patient outcomes using innovative therapies.

ATF3-SLC7A7 Axis Regulates mTORC1 Signaling to Suppress Lipogenesis and Tumorigenesis in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) poses a substantial global health burden, with poor prognosis and high mortality rates. Dysregulated lipid metabolism has emerged as a critical driver of HCC progression. While mTORC1 signaling is known to promote lipid synthesis in HCC, the regulatory mechanisms governing mTORC1 remain largely unclear. Here, we demonstrate that mTORC1 inhibition significantly reduces lipogenesis in HCC and uncover a regulatory axis involving the transcription factor ATF3 and the leucine-arginine transporter SLC7A7. Transcriptomic analysis of HCC patients reveals an inverse correlation between ATF3 expression and lipid synthesis, a finding corroborated by experimental validation. Mechanistically, ATF3 suppresses mTORC1 signaling, thereby inhibiting lipid biosynthesis, with SLC7A7 identified as a key intermediary in this process. Specifically, ATF3 binds to the enhancer region of SLC7A7, driving its transcriptional activation and subsequently restraining mTORC1 activity. Functional assays in ATF3-overexpressing and -knockdown HCC cell lines further confirm ATF3's role as a tumor suppressor. Our study identifies a novel ATF3-SLC7A7-mTORC1 regulatory axis that attenuates lipogenesis and tumorigenesis in HCC, establishing a critical link between lipid metabolism and hepatocarcinogenesis. These findings offer new insights into potential therapeutic targets for the treatment of HCC.

USP25 directly interacts with and deubiquitinates PPARα to increase PPARα stability in hepatocytes and attenuate high-fat diet-induced MASLD in mice

Recent studies have implicated altered ubiquitination/de-ubiquitination pathway in the pathogenesis of metabolic dysfunction-associated steatotic liver disease (MASLD). Here, we investigated the potential role of a deubiquitinase, ubiquitin-specific peptidase 25 (USP25), in MASLD. Analysis of mRNA profiling data showed that both human and mouse MASLD are associated with reduced expression of USP25 in hepatocytes. Usp25 deficiency exacerbated HFD-induced liver lipid accumulation and MASLD in mice. Rescue experiments with USP25 induction in hepatocytes protected mice against HFD-induced MASLD. Through comprehensive transcriptome sequence and pulldown-LC-MS/MS analysis, we identified that peroxisome proliferator-activated receptor α (PPARα) is involved in USP25's protective actions and may be the substrate protein of USP25. Cell-based experiments show that USP25 interacts with PPARα directly via its USP domain and the histidine at position 608 of USP25 exerts deubiquitination to increase protein stability by removing the K48 ubiquitin chain at PPARα's lysine at position 429. USP25 reduces palmitate (PA)-induced lipid accumulation in hepatocytes via increasing PPARα. Finally, we show that the protective effects of Usp25 induction are nullified in Ppara-deficient mice with HFD. In summary, this study presents a new USP25-PPARα axis in hepatocytes and highlights a novel function of USP25 in MASLD, suggesting that it may be targeted to combat the disease.

Integrating single-cell RNA-Seq and bulk RNA-Seq data to explore the key role of fatty acid metabolism in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a predominant cause of cancer-related mortality globally, noted for its propensity towards late-stage diagnosis and scarcity of effective treatment modalities. The process of metabolic reprogramming, with a specific emphasis on lipid metabolism, is instrumental in the progression of HCC. Nevertheless, the precise mechanisms through which lipid metabolism impacts HCC and its viability as a therapeutic target have yet to be fully elucidated. In the current investigation, single-cell RNA sequencing in conjunction with weighted gene co-expression network analysis (WGCNA) was utilized to delineate lipid metabolism-related genes correlated with the prognostic outcomes of hepatocellular carcinoma (HCC). Data procurement encompassed transcriptomic and clinical datasets from HCC patients, sourced from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) repositories. Subsequent to this, consensus clustering analysis was implemented to stratify patients into distinct subgroups, contingent upon the expression patterns of lipid metabolism genes. Further analytical procedures involved functional enrichment analysis, evaluation of immune infiltration, and examination of the mutation landscape.PTGES3 was identified as a pivotal gene associated with lipid metabolism. Subsequent to its identification, cellular communication analysis was employed to assess the immunological attributes of PTGES3 within the tumor microenvironment. The functional role of PTGES3 was further corroborated through molecular docking simulations and in vitro experimental assays. We identified 27 genes associated with lipid metabolism, 18 of which exhibited significant correlation with overall survival in HCC patients. PTGES3 emerged as a central gene, demonstrating a robust association with immune cell infiltration and unfavorable prognosis. Cellular communication analysis revealed that PTGES3 exhibits the highest communication intensity with T cells, modulating the tumor microenvironment by potentiating the FN1/CD44 + MDK/NCL signaling pathway. Elevated expression of PTGES3 was linked to immunosuppressive cascades, diminished responsiveness to immunotherapy, and inferior overall survival outcomes. Molecular docking analysis indicated that etoposide, methotrexate, and doxorubicin could effectively bind to PTGES3. In vitro experiments confirmed that PTGES3 knockdown significantly impaired the proliferation, invasion, and migration of HCC cells. This study highlights the pivotal role of lipid metabolism in HCC progression and identifies PTGES3 as a potential prognostic biomarker and therapeutic target. These findings offer new insights into the development of targeted therapies for HCC, particularly in patients with high PTGES3 expression.

Identification of Novel Organo-Se BTSA-Based Derivatives as Potent, Reversible, and Selective PPARγ Covalent Modulators for Antidiabetic Drug Discovery

Recent studies have identified selective peroxisome proliferator-activated receptor γ (PPARγ) modulators, which synergistically engage in the inhibition mechanism of PPARγ-Ser273 phosphorylation, as a promising approach for developing safer and more effective antidiabetic drugs. Herein, we present the design, synthesis, and evaluation of a new class of organo-Se compounds, namely, benzothiaselenazole-1-oxides (BTSAs), acting as potent, reversible, and selective PPARγ covalent modulators. Notably, 2n, especially (R)-2n, displayed a high binding affinity and superior antidiabetic effects with diminished side effects. This is mainly because it can reversibly form a unique covalent bond with the Cys285 residue in PPARγ-LBD. Further mechanistic investigations revealed that it manifested such desired pharmacological profiles primarily by effectively suppressing PPARγ-Ser273 phosphorylation, enhancing glucose metabolism, and selectively upregulating the expression of insulin-sensitive genes. Collectively, our results suggest that (R)-2n holds promise as a lead compound for treating T2DM and also provides an innovative reversible covalent warhead reference for future covalent drug design.

Hsp90α promotes lipogenesis by stabilizing FASN and promoting FASN transcription via LXRα in hepatocellular carcinoma

Excessive lipid accumulation promotes the occurrence and progression of hepatocellular carcinoma (HCC), accompanied by high levels of fatty acid synthetase (FASN) and more active lipogenesis. Heat shock protein 90 (Hsp90) acts as a chaperone to maintain the stability and activity of the client proteins. Studies have revealed that Hsp90 regulates the lipid metabolism of HCC, but the effect of Hsp90 on FASN still remains unknown. This study aims to discover the mechanism of Hsp90 inhibition on lipid accumulation and investigate the different effects of Hsp90 N-terminal domain inhibitor STA9090 and C-terminal domain inhibitor novobiocin on FASN protein stability and transcription pathway in HCC. We found that HCC cells tended to store lipids, which could be disrupted by Hsp90 inhibitors in vivo and in vitro. High levels of Hsp90α and FASN in tumor tissue had correlation with poor prognosis of HCC patients, and Hsp90α interacted with FASN to maintain its protein stability. Furthermore, N-terminal domain of Hsp90α was essential for process of sterol regulatory element binding protein 1 to activate FASN transcription and Hsp90α prevented proteasomal degradation of liver X receptor α to upregulate FASN transcription via liver X receptor α/sterol regulatory element binding protein 1 axis. Our data reveal that Hsp90α promotes lipid accumulation by increasing the protein stability and FASN mRNA transcription, and can be alleviated by Hsp90 inhibitors, which provides a theoretical basis for Hsp90-targeted therapy on lipid metabolism in HCC.

The ubiquitination degradation of KLF15 mediated by WSB2 promotes lipogenesis and progression of hepatocellular carcinoma via inhibiting PDLIM2 expression

BACKGROUND AND AIM

Krüppel-like factors15 (KLF15) is a cancer suppressor in many cancers. However, its precise function in the development of hepatocellular carcinoma (HCC) remains unclear. Lipogenesis is necessary for the development of HCC. This research aims to investigate the role of KLF15 in the regulation of hepatic lipid production and HCC progression.

METHODS

The binding relationships among genes were confirmed by ChIP, dual luciferase assays, and Co-IP. Lipogenesis was examined by oil red O staining. Triglyceride and cholesterol levels were measured through commercial kits. The effect of treatment on HCC cell viability, proliferation, migration, and invasion were assessed using CCK-8, clone formation, or transwell assays. A subcutaneous tumorigenic model was utilized to explore the effects of PDLIM2 in HCC in vivo.

RESULTS

KLF15 were downregulated in human HCC tissues. KLF15 overexpression reduced lipid droplet production, suppressed the expression of genes associated with lipogenesis, and promoted cell proliferation, migration, and invasion. KLF15 suppressed the NF-κB pathway through transcriptional activation of PDLIM2. PDLIM2 knockdown attenuated the effect of KLF15 overexpression on HCC. WSB2 degraded KLF15 through ubiquitination to promote HCC lipogenesis and development.

CONCLUSION

The ubiquitination degradation of KLF15 was mediated by WSB2, which led to transcriptional repression of PDLIM2 and further activation of the NF-κB pathway, ultimately promoting HCC lipogenesis and development.

IGFALS suppresses hepatocellular carcinoma progression by stabilizing PPAR-γ

IGFALS forms stable ternary complexes with insulin-like growth factors (IGF1 and IGF2) and IGF-binding proteins (IGFBP3 and IGFBP5), which prolong the half-lives of IGFs. Through immunohistochemical analysis of 90 pairs of clinical samples and bioinformatics analysis, we observed downregulation of IGFALS in hepatocellular carcinoma tissues, which was associated with poor patient prognosis. This prompted us to explore the specific molecular mechanism of action of IGFALS in the inhibition of hepatocellular carcinoma (HCC), which could be a potential new target for the treatment of HCC. In vitro experiments demonstrated that IGFALS inhibits the proliferation, invasion, and migration of hepatocellular carcinoma cells and suppresses epithelial-mesenchymal transition. Gene Set Enrichment Analysis (GSEA) revealed a positive correlation between IGFALS and the activation of the PPAR pathway. Western blotting, immunofluorescence colocalization, and co-immunoprecipitation assays confirmed that IGFALS binds to PPAR-γ and stabilizes it through deubiquitination. Inhibition of PPAR-γ reversed the anticancer effects of IGFALS. Furthermore, we showed that IGFALS/PPAR-γ upregulates the expression of HMGCS2. The tumor xenograft model supported our findings. Mass spectrometry analysis and co-immunoprecipitation assays indicated that IGFALS promotes the binding of PPAR-γ with USP9X, a deubiquitinating enzyme, thereby facilitating the deubiquitination of PPAR-γ. In conclusion, our findings demonstrate that IGFALS can suppress hepatocellular carcinoma via the PPAR-γ/HMGCS2 pathway.

Inhibition of USP22 by miR-200b-5p represses gastric cancer cell proliferation and migration by targeting the NF-κB signaling pathway

Gastric cancer (GC) is an aggressive tumor type with an intricate pathogenesis and limited therapeutic options. Ubiquitin-specific protease 22 (USP22) is a protein implicated in cell proliferation, metastasis, and tumorigenesis. However, the regulatory mechanisms governing USP22 in GC are still not fully understood. In this study, we perform bioinformatics analysis to identify conserved miRNA recognition sites for miR-200b-5p within the 3'UTR of USP22. Validation via luciferase reporter assay confirms the transcriptional regulation of USP22 by miR-200b-5p. Overexpression of miR-200b-5p markedly inhibits the proliferation and migration of GC cells in vitro and suppresses tumor growth in vivo. Conversely, ectopic expression of USP22 reversed this effect by modulating the NF-κB signaling pathway. Additionally, qPCR analysis reveals an inverse correlation between the miR-200b-5p level and USP22 expression in GC. Collectively, our findings indicate that miR-200b-5p-mediated inhibition of USP22 attenuates cell proliferation by targeting the NF-κB signaling pathway in GC, suggesting that miR-200b-5p and USP22 could serve as potential diagnostic or therapeutic targets for gastric cancer and other related human diseases.

Potential crosstalk between Naïve CD4+ T cells and SPP1+ Macrophages is associated with clinical outcome and therapeutic response in hepatocellular carcinoma

BACKGROUND

The highly heterogeneity of the tumor microenvironment (TME) in hepatocellular carcinoma (HCC) results in diverse clinical outcomes and therapeutic responses. This study aimed to investigate potential intercellular crosstalk and its impact on clinical outcomes and therapeutic responses.

METHODS

Single-cell RNA sequencing (scRNA-seq), spatial transcriptomics (ST) and bulk RNA sequencing (RNA-seq) datasets were integrated to comprehensively analyze the intercellular interactions within the TME. Multiplex immunohistochemistry was conducted to validate the intercellular interactions. A machine learning-based integrative procedure was used in bulk RNA-seq datasets to generate a risk model to predict prognosis and therapeutic responses.

RESULTS

Survival analyses based on the bulk RNA-seq datasets revealed the negative impact of the naïve Cluster of Differentiation 4+ (CD4) T cells and Secreted Phosphoprotein 1+ (SPP1) macrophages on prognosis. Furthermore, their intricate intercellular crosstalk and spatial colocalization were also observed by scRNA-seq and ST analyses. Based on this crosstalk, a machine learning model, termed the naïve CD4+ T cell and SPP1+ macrophage prognostic score (TMPS), was established in the bulk-RNA seq datasets for prognostic prediction. The TMPS achieved C-index values of 0.785, 0.715, 0.692 and 0.857, respectively, across 4 independent cohorts. A low TMPS was associated with a significantly increased survival rates, improved response to immunotherapy and reduced infiltration of immunosuppressive cells, such as. regulatory T cells. Finally, 8 potential sensitive drugs and 6 potential targets were predicted for patients based on their TMPS.

CONCLUSION

The crosstalk between naïve CD4+ T cells and SPP1+ macrophages play a crucial role in the TME. TMPS can reflect this crosstalk and serve as a valuable tool for prognostic stratification and guiding clinical decision-making.

Loss of USP10 promotes hepatocellular carcinoma proliferation by regulating the serine synthesis pathway through inhibition of LKB1 activity

Metabolic dysregulation is emerging as a critical factor in tumorigenesis, and reprogramming of serine metabolism has been identified as an essential factor in the progression of hepatocellular carcinoma (HCC). Studies have shown that LKB1 deficiency can activate mTOR to upregulate the serine synthesis pathway (SSP) and promote tumor progression. Our team discovered that ubiquitin-specific protease 10 (USP10) can inhibit HCC proliferation through mTOR, but its relationship with SSP needs further investigation. The metabolite assays revealed a significant increase in serine content in HCC tissues. Through the LKB1/mTOR/activating transcription factor 4 (ATF4) axis, loss of USP10 may increase serine biosynthesis and promote the proliferation of HCC in vitro and in vivo. Furthermore, it was found that USP10 could activate LKB1 through deubiquitination. Analyzing clinical HCC tissues revealed a positive correlation between USP10 and LKB1. Additionally, those with high expression of USP10 in HCC tissues showed a better degree of tumor differentiation and longer overall survival time. Moreover, we found increased expression of both serine and its synthase in liver tumor tissues of USP10 liver-specific KO mice. Loss of USP10 inhibits the activity of LKB1, contributing to the stimulation of the mTOR/ATF4 axis and SSP and then promoting the proliferation of HCC. This work presents a novel approach for serine-targeted treatment in HCC.

Zbtb7b defines a compensatory mechanism in MASLD-related HCC progression by suppressing H19-mediated hepatic lipid deposition

Hepatocellular carcinoma (HCC) is a widely prevalent type of primary liver cancer. However, strategies for pretumor intervention are still limited. In this study, a liver-specific Zbtb7b knockout mouse model was used to evaluate the role of Zbtb7b in metabolic dysfunction-associated steatotic liver disease (MASLD)-related HCC development. We revealed that Zbtb7b was compensatively increased and restricted lipid deposition in the liver during MASLD progression, which protects against MASLD-related HCC initiation. Mechanistically, Zbtb7b suppresses the expression of the long noncoding RNA H19 to attenuate hepatic de novo lipogenesis and increase fatty acid oxidation, thereby preventing lipid accumulation in hepatocytes. As a result, the proliferation and migration abilities of HCC cells are reduced. Overall, we demonstrated that Zbtb7b serves as a tumor suppressor at an early stage of HCC, thus providing a promising target for the treatment of HCC at a premalignant stage.

Deubiquitinases as novel therapeutic targets for diseases

Deubiquitinating enzymes (DUBs) regulate substrate ubiquitination by removing ubiquitin or cleaving within ubiquitin chains, thereby maintaining cellular homeostasis. Approximately 100 DUBs in humans counteract E3 ubiquitin ligases, finely balancing ubiquitination and deubiquitination processes to maintain cellular proteostasis and respond to various stimuli and stresses. Given their role in modulating ubiquitination levels of various substrates, DUBs are increasingly linked to human health and disease. Here, we review the DUB family, highlighting their distinctive structural characteristics and chain-type specificities. We show that DUB family members regulate key signaling pathways, such as NF-κB, PI3K/Akt/mTOR, and MAPK, and play crucial roles in tumorigenesis and other diseases (neurodegenerative disorders, cardiovascular diseases, inflammatory disorders, and developmental diseases), making them promising therapeutic targets Our review also discusses the challenges in developing DUB inhibitors and underscores the critical role of the DUBs in cellular signaling and cancer. This comprehensive analysis enhances our understanding of the complex biological functions of the DUBs and underscores their therapeutic potential.

Pentadecanoic acid (C15:0, PA) induces mild maternal glucose intolerance and promotes the growth of the offspring partly through up-regulating liver PPARα and MAPK signaling pathways

Gestational diabetes mellitus (GDM) is one of the most common metabolic disturbances during pregnancy, which poses a serious threat to both maternal and offspring health. Pentadecanoic acid (C15:0, PA) is one of the most common odd-chain saturated fatty acids (OCS-FAs). However, its safety and nutritional value are yet to be verified. Herein, we provide a systematic assessment of the effects of PA on maternal and progeny health and insulin sensitivity for the first time. Our results showed that consumption of 1% PA during pregnancy could increase the contents of PA and heptadecanoic acid (C17:0) in maternal plasma, fetal tissue and offspring plasma, but it had no effect on embryonic development. During pregnancy, PA treatment caused mild insulin resistance, while it had little effect on the maternal body composition. During lactation, PA treatment caused mild insulin resistance and oxidative stress. Maternal body fat deposition was also reduced, but the growth rate of the offspring was faster. It is worth noting that PA treatment decreased plasma and liver TG content and increased the antioxidant capacity of the offspring. The effect of PA on the transcription and expression genes in the liver of pregnant mice was investigated using RNA-seq. PPARα and MAPK signaling pathways, both closely related to lipolysis, inflammation, oxidative stress, and insulin resistance were significantly increased. The expression of c-JUN, ERK, JNK and P65 proteins was also significantly up-regulated. In conclusion, our results suggest that 1% PA can induce a mild decrease in the maternal glucose tolerance and lipolysis mainly by activated MAPK and PPARα signaling. Moreover, low concentrations of PA may be an effective nutrient to alleviate the oxidative stress and reduce blood lipid levels of offspring.

USP11 promotes lipogenesis and tumorigenesis by regulating SREBF1 stability in hepatocellular carcinoma

BACKGROUND

The relationship between hepatocellular carcinoma (HCC) metastasis and cancer metabolism reprogramming is becoming increasingly evident. Ubiquitin-specific protease 11 (USP11), a member of the deubiquitinating enzyme family, has been linked to various cancer-related processes. While USP11 is known to promote HCC metastasis and proliferation, the precise mechanisms, especially those related to cancer metabolism, remain unclear.

METHODS

Through mass spectrometry, co-immunoprecipitation, immunofluorescence, and ubiquitination assays, we identified USP11 as the key deubiquitinase for SREBF1.Lipogenesis was evaluated using Oil Red O and Nile Red staining, along with the detection of triglycerides and cholesterol. To assess HCC cell proliferation, migration, and invasion in vitro, Transwell assays, EDU, colony formation, and CCK-8 were conducted. Xenograft models in nude mice were developed to verify the role of the USP11/SREBF1 axis in lipogenesis and tumor growth in vivo.

RESULTS

USP11 directly interacts with SREBF1, and its silencing leads to the disruption of SREBF1 stabilization through K48-linked deubiquitination and degradation. Importantly, the truncated mutant USP11 (503-938 aa) interacts with the truncated mutant SREBF1 (569-1147aa), with K1151 playing a crucial role in this interaction. Higher levels of USP11 enhance lipogenesis, proliferation, and metastasis in HCC cells. Importantly, the knockdown of SREBF1 weakened the effects of USP11 in enhancing lipogenesis and tumorigenesis. Futhermore, the elevated expression of USP11 and SREBF1 in HCC tissue serves as an indicator of poor prognosis in HCC patients.

CONCLUSIONS

In summary, our study reveals that USP11 promotes HCC proliferation and metastasis through SREBF1-induced lipogenesis. These findings provide a foundation for novel therapies targeting lipid metabolism in HCC.

Aberrant Energy Metabolism in Tumors and Potential Therapeutic Targets

Energy metabolic reprogramming is frequently observed during tumor progression as tumor cells necessitate adequate energy production for rapid proliferation. Although current medical research shows promising prospects in studying the characteristics of tumor energy metabolism and developing anti-tumor drugs targeting energy metabolism, there is a lack of systematic compendiums and comprehensive reviews in this field. The objective of this study is to conduct a systematic review on the characteristics of tumor cells' energy metabolism, with a specific focus on comparing abnormalities between tumor and normal cells, as well as summarizing potential targets for tumor therapy. Additionally, this review also elucidates the aberrant mechanisms underlying four major energy metabolic pathways (glucose, lipid, glutamine, and mitochondria-dependent) during carcinogenesis and tumor progression. Through the utilization of graphical representations, we have identified anomalies in crucial energy metabolism pathways, encompassing transporter proteins (glucose transporter, CD36, and ASCT2), signaling molecules (Ras, AMPK, and PTEN), as well as transcription factors (Myc, HIF-1α, CREB-1, and p53). The key molecules responsible for aberrant energy metabolism in tumors may serve as potential targets for cancer therapy. Therefore, this review provides an overview of the distinct energy-generating pathways within tumor cells, laying the groundwork for developing innovative strategies for precise cancer treatment.

USP22 promotes gefitinib resistance and inhibits ferroptosis in non-small cell lung cancer by deubiquitination of MDM2

BACKGROUND

The emergence of chemoresistance markedly compromised the treatment efficiency of human cancer, including non-small cell lung cancer (NSCLC). In the present study, we aimed to explore the effects of ubiquitin-specific peptidase 22 (USP22) and murine double minute 2 (MDM2) in gefitinib resistance in NSCLC.

METHODS

Immunohistochemistry (IHC) assay, quantitative real-time polymerase chain reaction (qRT-PCR) assay and western blot assay were carried out to determine the expression of USP22 and MDM2. Transwell assay and flow cytometry analysis were performed to evaluate cell migration and apoptosis. Cell Counting Kit-8 (CCK-8) assay was employed to assess gefitinib resistance. The phenomenon of ferroptosis was estimated by related commercial kits. The oxidized C11-BODIPY fluorescence intensity by C11-BODIPY staining. The relation between USP22 and MDM2 was analyzed by ubiquitination assay and co-immunoprecipitation (Co-IP) assay.

RESULTS

USP22 was abnormally upregulated in NSCLC tissues and cells, and USP22 silencing markedly repressed NSCLC cell migration and facilitated apoptosis and ferroptosis. Moreover, our results indicated that ferroptosis could enhance the suppressive effect of gefitinib on NSCLC cells. Besides, USP22 overexpression enhanced gefitinib resistance and ferroptosis protection in NSCLC cells. Mechanically, USP22 stabilized MDM2 and regulated MDM2 expression through deubiquitination of MDM2. MDM2 deficiency partially restored the effects of USP22 on gefitinib resistance and ferroptosis in NSCLC cells. Of note, we validated the promotional effect of USP22 on gefitinib resistance in NSCLC in vivo through establishing the murine xenograft model.

CONCLUSION

USP22/MDM2 promoted gefitinib resistance and inhibited ferroptosis in NSCLC, which might offer a novel strategy for overcoming gefitinib resistance in NSCLC.

Epidemiology, pathophysiology and clinical aspects of Hepatocellular Carcinoma in MAFLD patients

Hepatocellular carcinoma (HCC) is undergoing a transformative shift, with metabolic-associated fatty liver disease (MAFLD) emerging as a dominant etiology. Diagnostic criteria for MAFLD involve hepatic steatosis and metabolic dysregulation. Globally, MAFLD prevalence stands at 38.77%, significantly linked to the escalating rates of obesity. Epidemiological data indicate a dynamic shift in the major etiologies of hepatocellular carcinoma (HCC), transitioning from viral to metabolic liver diseases. Besides the degree of liver fibrosis, several modifiable lifestyle risk factors, such as type 2 diabetes, obesity, alcohol use, smoking, and HBV, HCV infection contribute to the pathogenesis of HCC. Moreover  gut microbiota and genetic variants may contribute to HCC development.The pathophysiological link between MAFLD and HCC involves metabolic dysregulation, impairing glucose and lipid metabolism, inflammation and oxidative stress. Silent presentation poses challenges in early MAFLD-HCC diagnosis. Imaging, biopsy, and AI-assisted techniques aid diagnosis, while HCC surveillance in non-cirrhotic MAFLD patients remains debated.ITA.LI.CA. group proposes a survival-based algorithm for treatment based on Barcelona clinic liver cancer (BCLC) algorithm. Liver resection, transplantation, ablation, and locoregional therapies are applied based on the disease stage. Systemic treatments is promising, with initial immunotherapy results indicating a less favorable response in MAFLD-related HCC.Adopting lifestyle interventions and chemopreventive measures with medications, including aspirin, metformin, and statins, constitute promising approaches for the primary prevention of HCC.Prognosis is influenced by multiple factors, with MAFLD-HCC associated with prolonged survival. Emerging diagnostic biomarkers and epigenomic markers, show promising results for early HCC detection in the MAFLD population.

Protein posttranslational modifications in metabolic diseases: basic concepts and targeted therapies

Metabolism-related diseases, including diabetes mellitus, obesity, hyperlipidemia, and nonalcoholic fatty liver disease, are becoming increasingly prevalent, thereby posing significant threats to human health and longevity. Proteins, as the primary mediators of biological activities, undergo various posttranslational modifications (PTMs), including phosphorylation, ubiquitination, acetylation, methylation, and SUMOylation, among others, which substantially diversify their functions. These modifications are crucial in the physiological and pathological processes associated with metabolic disorders. Despite advancements in the field, there remains a deficiency in contemporary summaries addressing how these modifications influence processes of metabolic disease. This review aims to systematically elucidate the mechanisms through which PTM of proteins impact the progression of metabolic diseases, including diabetes, obesity, hyperlipidemia, and nonalcoholic fatty liver disease. Additionally, the limitations of the current body of research are critically assessed. Leveraging PTMs of proteins provides novel insights and therapeutic targets for the prevention and treatment of metabolic disorders. Numerous drugs designed to target these modifications are currently in preclinical or clinical trials. This review also provides a comprehensive summary. By elucidating the intricate interplay between PTMs and metabolic pathways, this study advances understanding of the molecular mechanisms underlying metabolic dysfunction, thereby facilitating the development of more precise and effective disease management strategies.

ATP citrate lyase promotes the progression of hepatocellular carcinoma by activating the REGγ-proteasome pathway

The search for novel tumor biomarkers and targets is of significant importance for the early clinical diagnosis and treatment of Hepatocellular Carcinoma (HCC). The mechanisms by which ATP citrate lyase (ACLY) promotes HCC progression remain unclear, and the connection between ACLY and REGγ has not been reported in the literature. In vitro, we will perform overexpression/knockdown of ACLY or overexpression/knockdown of REGγ to investigate the impact of ACLY on HCC cells and its underlying mechanisms. In vivo, we will establish mouse tumor models with overexpression/knockdown of ACLY or overexpression/knockdown of REGγ to study the effect of ACLY on mouse tumors and its mechanisms. Firstly, ACLY overexpression upregulated REGγ expression and activated the REGγ-proteasome pathway, leading to changes in the expression of downstream signaling pathway proteins. This promoted HCC cell proliferation, invasion, and migration in vitro, as well as tumor growth and metastasis in vivo. Secondly, ACLY overexpression increased acetyl-CoA production, upregulated the acetylation level of the REGγ promoter region histone H3K27ac, and subsequently induced REGγ expression. Lastly, enhanced acetylation of the REGγ promoter region histone H3K27ac resulted in upregulated REGγ expression, activation of the REGγ-proteasome pathway, changes in downstream signaling pathway protein expression, and promotion of HCC cell proliferation, invasion, and migration in vitro, as well as tumor growth and metastasis in vivo. Conversely, REGγ knockdown reversed these effects. ACLY and REGγ may serve as potential biomarkers and clinical therapeutic targets for HCC.

Ubiquitin-Specific Protease 22 Plays a Key Role in Increasing Extracellular Vesicle Secretion and Regulating Cell Motility of Lung Adenocarcinoma

Tumor-derived extracellular vesicles (EVs) are potential biomarkers for tumors, but their reliable molecular targets have not been identified. The previous study confirms that ubiquitin-specific protease 22 (USP22) promotes lung adenocarcinoma (LUAD) metastasis in vivo and in vitro. Moreover, USP22 regulates endocytosis of tumor cells and localizes to late endosomes. However, the role of USP22 in the secretion of tumor cell-derived EVs remains unknown. In this study, it demonstrates that USP22 increases the secretion of tumor cell-derived EVs and accelerates their migration and invasion, invadopodia formation, and angiogenesis via EV transfer. USP22 enhances EV secretion by upregulating myosin IB (MYO1B). This study further discovers that USP22 activated the SRC signaling pathway by upregulating the molecule KDEL endoplasmic reticulum protein retention receptor 1 (KDELR1), thereby contributing to LUAD cell progression. The study provides novel insights into the role of USP22 in EV secretion and cell motility regulation in LUAD.

An integrative pan-cancer analysis of MASP1 and the potential clinical implications for the tumor immune microenvironment

Mannose-binding lectin-associated serine protease 1 (MASP1) plays a crucial role in the complement lectin pathway and the mediation of immune responses. However, comprehensive research on MASP1 across various cancer types has not been performed to date. This study aimed to evaluate the significance of MASP1 in pan-cancer. The Cancer Genome Atlas (TCGA), UCSC Xena and Genotype Tissue Expression (GTEx) databases were used to evaluate the expression profiles, genomic features, prognostic relevance, and immune microenvironment associations of MASP1 across 33 cancer types. We observed significant dysregulation of MASP1 expression in multiple cancers, with strong associations between MASP1 expression levels and diagnostic value as well as patient prognosis. Mechanistic insights revealed significant correlations between MASP1 levels and various immunological and genomic factors, including tumor-infiltrating immune cells (TIICs), immune-related genes, mismatch repair (MMR), tumor mutation burden (TMB), and microsatellite instability (MSI), highlighting a critical regulatory function of MASP1 within the tumor immune microenvironment (TIME). In vitro and in vivo experiments demonstrated that MASP1 expression was markedly decreased in liver hepatocellular carcinoma (LIHC). Moreover, the overexpression of MASP1 in hepatocellular carcinoma (HCC) cell lines significantly inhibited their proliferation, invasion and migration. In conclusion, MASP1 exhibits differential expression in the pan-cancer analyses and might play an important role in TIME. MASP1 is a promising prognostic biomarker and a potential target for immunological research, particularly in LIHC.

USP26 as a hepatitis B virus-induced deubiquitinase primes hepatocellular carcinogenesis by epigenetic remodeling

Despite recent advances in systemic therapy for hepatocellular carcinoma (HCC), the prognosis of hepatitis B virus (HBV)-induced HCC patients remains poor. By screening a sgRNA library targeting human deubiquitinases, we find that ubiquitin-specific peptidase 26 (USP26) deficiency impairs HBV-positive HCC cell proliferation. Genetically engineered murine models with Usp26 knockout confirm that Usp26 drives HCC tumorigenesis. Mechanistically, we find that the HBV-encoded protein HBx binds to the promoter and induces the production of USP26, which is an X-linked gene exclusively expressed in the testis. HBx consequently promotes the association of USP26 with SIRT1 to synergistically stabilize SIRT1 by deubiquitination, which promotes cell proliferation and impedes cell apoptosis to accelerate HCC tumorigenesis. In patients with HBV-positive HCC, USP26 is robustly induced, and its levels correlate with SIRT1 levels and poor prognosis. Collectively, our study highlights a causative link between HBV infection, deubiquitinase induction and development of HCC, identifying a druggable target, USP26.

Overexpression of USP22 ameliorates LPS-induced endometrial stromal cells inflammation and modulates cells decidualization by inhibiting ferroptosis

Endometritis and the failure of decidualization of the endometrium are important factors contributing to the increased incidence of abortion. USP22 is associated with various inflammatory diseases and has been shown to be involved in endometrial decidualization in mice. This study aims to investigate whether USP22 is involved in the regulation of inflammatory response and decidualization in human endometrial stromal cells (hESCs). In this study, lipopolysaccharide (LPS) was used to induce inflammation in hESCs, and MPA combined with cAMP was used to induce decidualization of hESCs. USP22 overexpression vector was constructed to study the role of USP22 in endometritis. The results showed that the USP22 protein and mRNA levels were decreased in LPS-induced hESCs. LPS induction increased the levels of TNF-α, IL-1β, and IL-6, as well as the expression of iNOS and COX2 proteins in hESCs. In the LPS group, the levels of F-actin, PRL, IGFBP1, SLC7A11, and GPX4 proteins decreased, while the levels of lipid peroxidation and total iron content increased. Additionally, the levels of ACSL4 and TFR1 proteins were up-regulated. Overexpression of USP22 reversed LPS-induced cellular inflammation, attenuated decidualization, and inhibited ferroptosis. However, the use of ferroptosis inducers diminished the regulatory effects of USP22 on inflammatory responses and decidualization. In summary, these suggested that USP22 reduces the LPS-induced inflammatory response and regulates the decidualization of hESCs, and possibly involving ferroptosis.

USP22 is required for human endometrial stromal cell proliferation and decidualization by deubiquitinating FoxM1

Despite significant advances in assisted reproductive technology (ART), recurrent implantation failure (RIF) still occurs in some patients. Poor endometrial receptivity and abnormal human endometrial stromal cell (HESC) proliferation and decidualization have been identified as the major causes. Ubiquitin-specific protease 22 (USP22) has been reported to participate in the decidualization of endometrial stromal cells in mice. However, the role of USP22 in HESC function and RIF development remains unknown. In this study, clinical endometrial tissue samples were gathered to investigate the involvement of USP22 in RIF, and HESCs were utilized to examine the molecular mechanisms of USP22 and Forkhead box M1 (FoxM1). The findings indicated a high expression of USP22 in the secretory phase of the endometrium. Knockdown of USP22 led to a notable reduction in the proliferation and decidualization of HESCs, along with a decrease in FoxM1 expression, while overexpression of USP22 yielded opposite results. Furthermore, USP22 was found to deubiquitinate FoxM1 in HESCs. Moreover, both USP22 and FoxM1 were downregulated in the endometria of patients with RIF. In conclusion, these results suggest that USP22 may have a significant impact on HESCs proliferation and decidualization through its interaction with FoxM1, potentially contributing to the underlying mechanisms of RIF pathogenesis.

Ubiquitination and De-Ubiquitination in the Synthesis of Cow Milk Fat: Reality and Prospects

Ubiquitination modifications permit the degradation of labelled target proteins with the assistance of proteasomes and lysosomes, which is the main protein degradation pathway in eukaryotic cells. Polyubiquitination modifications of proteins can also affect their functions. De-ubiquitinating enzymes reverse the process of ubiquitination via cleavage of the ubiquitin molecule, which is known as a de-ubiquitination. It was demonstrated that ubiquitination and de-ubiquitination play key regulatory roles in fatty acid transport, de novo synthesis, and desaturation in dairy mammary epithelial cells. In addition, natural plant extracts, such as stigmasterol, promote milk fat synthesis in epithelial cells via the ubiquitination pathway. This paper reviews the current research on ubiquitination and de-ubiquitination in dairy milk fat production, with a view to providing a reference for subsequent research on milk fat and exploring new directions for the improvement of milk quality.

Polyphyllin I exerts anti-hepatocellular carcinoma activity by targeting ZBTB16 to activate the PPARγ/RXRα signaling pathway

BACKGROUND

Studies have reported that polyphyllin I (PPI) had effective anti-tumor activity against hepatocellular carcinoma (HCC). However, the precise molecular mechanism of this action and the direct target remain unclear. The aim of this study was to discover the molecular targets and the exact mechanism of PPI in the treatment of HCC.

METHODS

Various HCC cells and Zebrafish xenotransplantation models were used to examine the efficacy of PPI against HCC. A proteome microarray, surface plasmon resonance (SPR) analysis, small molecule transfection, and molecular docking were conducted to confirm the direct binding targets of PPI. Transcriptome and Western blotting were then used to determine the exact responding mechanism. Finally, the anticancer effect and its precise mechanism, as well as the safety of PPI, were verified using a mouse tumor xenograft study.

RESULTS

The results demonstrated that PPI had significant anticancer activity against HCC in both in vitro studies of two cells and the zebrafish model. Notably, PPI selectively enhanced the action of the Zinc finger and BTB domain-containing 16 (ZBTB16) protein by directly binding to it. Furthermore, specific knockdown of ZBTB16 markedly attenuated PPI-dependent inhibition of HCC cell proliferation and migration caused by overexpression of the gene. The transcriptome and Western blotting also confirmed that the interaction between ZBTB16 and PPI also activated the PPARγ/RXRα pathway. Finally, the mouse experiments confirmed the efficacy and safety of PPI to treat HCC.

CONCLUSIONS

Our results indicate that ZBTB16 is a promising drug target for HCC and that PPI as a potent ZBTB16 agonist has potential as a therapeutic agent against HCC by regulating the ZBTB16/PPARγ/RXRα signaling axis.

Epinephrine promotes breast cancer metastasis through a ubiquitin-specific peptidase 22-mediated lipolysis circuit

Chronic stress-induced epinephrine (EPI) accelerates breast cancer progression and metastasis, but the molecular mechanisms remain unclear. Herein, we found a strong positive correlation between circulating EPI levels and the tumoral expression of ubiquitin-specific peptidase 22 (USP22) in patients with breast cancer. USP22 facilitated EPI-induced breast cancer progression and metastasis by enhancing adipose triglyceride lipase (ATGL)-mediated lipolysis. Targeted USP22 deletion decreased ATGL expression and lipolysis, subsequently inhibiting EPI-mediated breast cancer lung metastasis. USP22 acts as a bona fide deubiquitinase for the Atgl gene transcription factor FOXO1, and EPI architects a lipolysis signaling pathway to stabilize USP22 through AKT-mediated phosphorylation. Notably, USP22 phosphorylation levels are positively associated with EPI and with downstream pathways involving both FOXO1 and ATGL in breast cancers. Pharmacological USP22 inhibition synergized with β-blockers in treating preclinical xenograft breast cancer models. This study reveals a molecular pathway behind EPI's tumor-promoting effects and provides a strong rationale for combining USP22 inhibition with β-blockers to treat aggressive breast cancer.

Lecithin-cholesterol acyltransferase is a potential tumor suppressor and predictive marker for hepatocellular carcinoma metastasis

BACKGROUND

Hepatocellular carcinoma (HCC) is a major cause of cancer mortality worldwide, and metastasis is the main cause of early recurrence and poor prognosis. However, the mechanism of metastasis remains poorly understood.

AIM

To determine the possible mechanism affecting HCC metastasis and provide a possible theoretical basis for HCC treatment.

METHODS

The candidate molecule lecithin-cholesterol acyltransferase (LCAT) was screened by gene microarray and bioinformatics analysis. The expression levels of LCAT in clinical cohort samples was detected by quantitative real-time polymerase chain reaction and western blotting. The proliferation, migration, invasion and tumor-forming ability were measured by Cell Counting Kit-8, Transwell cell migration, invasion, and clonal formation assays, respectively. Tumor formation was detected in nude mice after LCAT gene knockdown or overexpression. The immunohistochemistry for Ki67, E-cadherin, N-cadherin, matrix metalloproteinase 9 and vascular endothelial growth factor were performed in liver tissues to assess the effect of LCAT on HCC. Gene set enrichment analysis (GSEA) on various gene signatures were analyzed with GSEA version 3.0. Three machine-learning algorithms (random forest, support vector machine, and logistic regression) were applied to predict HCC metastasis in The Cancer Genome Atlas and GEO databases.

RESULTS

LCAT was identified as a novel gene relating to HCC metastasis by using gene microarray in HCC tissues. LCAT was significantly downregulated in HCC tissues, which is correlated with recurrence, metastasis and poor outcome of HCC patients. Functional analysis indicated that LCAT inhibited HCC cell proliferation, migration and invasion both in vitro and in vivo. Clinicopathological data showed that LCAT was negatively associated with HCC size and metastasis (HCC size ≤ 3 cm vs 3-9 cm, P < 0.001; 3-9 cm vs > 9 cm, P < 0.01; metastatic-free HCC vs extrahepatic metastatic HCC, P < 0.05). LCAT suppressed the growth, migration and invasion of HCC cell lines via PI3K/AKT/mTOR signaling. Our results indicated that the logistic regression model based on LCAT, TNM stage and the serum level of α-fetoprotein in HCC patients could effectively predict high metastatic risk HCC patients.

CONCLUSION

LCAT is downregulated at translational and protein levels in HCC and might inhibit tumor metastasis via attenuating PI3K/AKT/mTOR signaling. LCAT is a prognostic marker and potential therapeutic target for HCC.

Acetylation-dependent deubiquitinase USP26 stabilizes BAG3 to promote breast cancer progression

Deubiquitylases (DUBs) have emerged as promising targets for cancer therapy due to their role in stabilizing substrate proteins within the ubiquitin machinery. Here, we identified ubiquitin-specific protease 26 (USP26) as an oncogene via screening prognostic DUBs in breast cancer. Through in vitro and in vivo experiments, we found that depletion of USP26 inhibited breast cancer cell proliferation and invasion, and suppressed tumor growth and metastasis in nude mice. Further investigation identified co-chaperone Bcl-2-associated athanogene 3 (BAG3) as the direct substrate of USP26, and ectopic expression of BAG3 partially reversed antitumor effect induced by USP26 knockdown. Mechanistically, the lysine acetyltransferase Tip60 targeted USP26 at K134 for acetylation, which enhanced USP26 binding affinity to BAG3, leading to BAG3 deubiquitination and increased protein stability. Importantly, we employed a structure-based virtual screening and discovered a drug-like molecule called 5813669 that targets USP26, destabilizing BAG3 and effectively mitigating tumor growth and metastasis in vivo. Clinically, high expression levels of USP26 were correlated with elevated BAG3 levels and poor prognosis in breast cancer patients. Overall, our findings highlight the critical role of USP26 in BAG3 protein stabilization and provide a promising therapeutic target for breast cancer.

Roles of the peroxisome proliferator-activated receptors (PPARs) in the pathogenesis of hepatocellular carcinoma (HCC)

Hepatocellular carcinoma (HCC) holds a prominent position among global cancer types. Classically, HCC manifests in individuals with a genetic predisposition when they encounter risk elements, particularly in the context of liver cirrhosis. Peroxisome proliferator-activated receptors (PPARs), which are transcription factors activated by fatty acids, belong to the nuclear hormone receptor superfamily and play a pivotal role in the regulation of energy homeostasis. At present, three distinct subtypes of PPARs have been recognized: PPARα, PPARγ, and PPARβ/δ. They regulate the transcription of genes responsible for cellular development, energy metabolism, inflammation, and differentiation. In recent years, with the rising incidence of HCC, there has been an increasing focus on the mechanisms and roles of PPARs in HCC. PPARα primarily mediates the occurrence and development of HCC by regulating glucose and lipid metabolism, inflammatory responses, and oxidative stress. PPARβ/δ is closely related to the self-renewal ability of liver cancer stem cells (LCSCs) and the formation of the tumor microenvironment. PPARγ not only influences tumor growth by regulating the glucose and lipid metabolism of HCC, but its agonists also have significant clinical significance for the treatment of HCC. Therefore, this review offers an exhaustive examination of the role of the three PPAR subtypes in HCC progression, focusing on their mediation of critical cellular processes such as glucose and lipid metabolism, inflammation, oxidative stress, and other pivotal signaling pathways. At the end of the review, we discuss the merits and drawbacks of existing PPAR-targeted therapeutic strategies and suggest a few alternative combinatorial therapeutic approaches that diverge from conventional methods.

PPAR-γ/NF-kB/AQP3 axis in M2 macrophage orchestrates lung adenocarcinoma progression by upregulating IL-6

Aquaporin 3 (AQP3), which is mostly expressed in pulmonary epithelial cells, was linked to lung adenocarcinoma (LUAD). However, the underlying functions and mechanisms of AQP3 in the tumor microenvironment (TME) of LUAD have not been elucidated. Single-cell RNA sequencing (scRNA-seq) was used to study the composition, lineage, and functional states of TME-infiltrating immune cells and discover AQP3-expressing subpopulations in five LUAD patients. Then the identifications of its function on TME were examined in vitro and in vivo. AQP3 was associated with TNM stages and lymph node metastasis of LUAD patients. We classified inter- and intra-tumor diversity of LUAD into twelve subpopulations using scRNA-seq analyses. The analysis showed AQP3 was mainly enriched in subpopulations of M2 macrophages. Importantly, mechanistic investigations indicated that AQP3 promoted M2 macrophage polarization by the PPAR-γ/NF-κB axis, which affected tumor growth and migration via modulating IL-6 production. Mixed subcutaneous transplanted tumor mice and Aqp3 knockout mice models were further utilized, and revealed that AQP3 played a critical role in mediating M2 macrophage polarization, modulating glucose metabolism in tumors, and regulating both upstream and downstream pathways. Overall, our study demonstrated that AQP3 could regulate the proliferation, migration, and glycometabolism of tumor cells by modulating M2 macrophages polarization through the PPAR-γ/NF-κB axis and IL-6/IL-6R signaling pathway, providing new insight into the early detection and potential therapeutic target of LUAD.

Ubiquitination and deubiquitination in cancer: from mechanisms to novel therapeutic approaches

Ubiquitination, a pivotal posttranslational modification of proteins, plays a fundamental role in regulating protein stability. The dysregulation of ubiquitinating and deubiquitinating enzymes is a common feature in various cancers, underscoring the imperative to investigate ubiquitin ligases and deubiquitinases (DUBs) for insights into oncogenic processes and the development of therapeutic interventions. In this review, we discuss the contributions of the ubiquitin-proteasome system (UPS) in all hallmarks of cancer and progress in drug discovery. We delve into the multiple functions of the UPS in oncology, including its regulation of multiple cancer-associated pathways, its role in metabolic reprogramming, its engagement with tumor immune responses, its function in phenotypic plasticity and polymorphic microbiomes, and other essential cellular functions. Furthermore, we provide a comprehensive overview of novel anticancer strategies that leverage the UPS, including the development and application of proteolysis targeting chimeras (PROTACs) and molecular glues.

Crosstalk between Epigenetics and Metabolic Reprogramming in Metabolic Dysfunction-Associated Steatotic Liver Disease-Induced Hepatocellular Carcinoma: A New Sight

Epigenetic and metabolic reprogramming alterations are two important features of tumors, and their reversible, spatial, and temporal regulation is a distinctive hallmark of carcinogenesis. Epigenetics, which focuses on gene regulatory mechanisms beyond the DNA sequence, is a new entry point for tumor therapy. Moreover, metabolic reprogramming drives hepatocellular carcinoma (HCC) initiation and progression, highlighting the significance of metabolism in this disease. Exploring the inter-regulatory relationship between tumor metabolic reprogramming and epigenetic modification has become one of the hot directions in current tumor metabolism research. As viral etiologies have given way to metabolic dysfunction-associated steatotic liver disease (MASLD)-induced HCC, it is urgent that complex molecular pathways linking them and hepatocarcinogenesis be explored. However, how aberrant crosstalk between epigenetic modifications and metabolic reprogramming affects MASLD-induced HCC lacks comprehensive understanding. A better understanding of their linkages is necessary and urgent to improve HCC treatment strategies. For this reason, this review examines the interwoven landscape of molecular carcinogenesis in the context of MASLD-induced HCC, focusing on mechanisms regulating aberrant epigenetic alterations and metabolic reprogramming in the development of MASLD-induced HCC and interactions between them while also updating the current advances in metabolism and epigenetic modification-based therapeutic drugs in HCC.

Role of lipid metabolism in hepatocellular carcinoma

Hepatocellular carcinoma (HCC), an aggressive malignancy with a dismal prognosis, poses a significant public health challenge. Recent research has highlighted the crucial role of lipid metabolism in HCC development, with enhanced lipid synthesis and uptake contributing to the rapid proliferation and tumorigenesis of cancer cells. Lipids, primarily synthesized and utilized in the liver, play a critical role in the pathological progression of various cancers, particularly HCC. Cancer cells undergo metabolic reprogramming, an essential adaptation to the tumor microenvironment (TME), with fatty acid metabolism emerging as a key player in this process. This review delves into intricate interplay between HCC and lipid metabolism, focusing on four key areas: de novo lipogenesis, fatty acid oxidation, dysregulated lipid metabolism of immune cells in the TME, and therapeutic strategies targeting fatty acid metabolism for HCC treatment.

Tumor-associated macrophage-induced circMRCKα encodes a peptide to promote glycolysis and progression in hepatocellular carcinoma

The tumor-associated macrophages (TAMs) play multifaceted roles in the progression of hepatocellular carcinoma (HCC). However, the involvement of circular RNAs in the interplay between TAMs and HCC remains unclear. Based on Transwell co-culturing and circular RNA sequencing, this study revealed that TAMs enhanced tumor glycolysis and progression by upregulating circMRCKα in HCC cells. Patients with HCC who exhibited elevated circMRCKα levels presented significantly reduced overall survival and greater cumulative recurrence. Notably, we identified a novel functional peptide of 227 amino acids named circMRCKα-227aa, encoded by circMRCKα. Mechanistically, circMRCKα-227aa bound to USP22 and enhanced its protein level to obstruct HIF-1α degradation via the ubiquitin-proteasome pathway, thereby augmenting HCC glycolysis and progression. In clinical HCC samples, a positive correlation was observed between the expression of circMRCKα and the number of infiltrating CD68+ TAMs and expression of USP22. Furthermore, circMRCKα emerged as an independent prognostic risk factor both individually and in conjunction with CD68+ TAMs and USP22. This study illustrated that circMRCKα-227aa, a novel TAM-induced peptide, promotes tumor glycolysis and progression via USP22 binding and HIF-1α upregulation, suggesting that circMRCKα and TAMs could be combined as therapeutic targets in HCC.

FOXP3 (in)stability and cancer immunotherapy

Dysregulation of regulatory T cells (Tregs) is described in the context of inflammatory and autoimmune diseases, and cancer. Forkhead box P3 (FOXP3) is a transcription factor that its activity is an indicator of Treg identity. FOXP3 induces metabolic versatility in intra-tumoral Tregs, so that its deficiency mediates Treg instability or even gives rise to the acquisition of effector T cell phenotype. FOXP3 dysregulation and defectiveness occurs upon ubiquitination, methylation and presumably acetylation. Stimulators of PTEN, mammalian target of rapamycin complex 2 (mTORC2), and nucleus accumbens-associated protein-1 (NAC1), and inhibitors of B lymphocyte-induced maturation protein-1 (Blimp-1), Deltex1 (DTX1) and ubiquitin-specific peptidase 22 (USP22) are suggested to hamper FOXP3 stability, and to promote its downregulation and further Treg depletion. A point is that Treg subsets reveal different reliance on FOXP3, which indicates that not all Tregs are strictly dependent on FOXP3, and presumably Tregs with different origin rely on diverse regulators of FOXP3 stability. The focus of this review is over the current understanding toward FOXP3, its activity in Tregs and influence from different regulators within tumor microenvironment (TME). Implication of FOXP3 targeting in cancer immunotherapy is another focus of this paper.

USP22 as a key regulator of glycolysis pathway in osteosarcoma: insights from bioinformatics and experimental approaches

Background

Osteosarcoma is the most common primary malignant bone tumor, but its pathogenesis remains unclear. Ubiquitin-specific processing peptidase 22 (USP22) is reported to be highly expressed and associated with tumor malignancy and prognosis in cancers. However, the role and mechanism of USP22 in osteosarcoma is not fully understood. This study aims to investigate the function and potential mechanism of USP22 in osteosarcoma using bioinformatics analysis combined with experimental validation.

Methods

We first integrated transcriptomic datasets and clinical information of osteosarcoma from GEO and TCGA databases to assess the expression and prognostic value of USP22 in osteosarcoma. Then, differential expression analysis and weighted gene co-expression network analysis (WGCNA) were conducted to identify USP22-related co-expressed genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to explore the biological functions and signaling pathways of USP22 co-expressed genes. To validate the accuracy of bioinformatics analyses, we downregulated USP22 expression in osteosarcoma cell line Sao-2 using siRNA and assessed its effect on cell proliferation, migration, invasion, apoptosis, and regulation of key signaling pathways.

Results

We found that USP22 was highly expressed in osteosarcoma tissues and correlated with poor prognosis in osteosarcoma patients. USP22 also showed potential as a diagnostic marker for osteosarcoma. In addition, 344 USP22-related co-expressed genes were identified, mainly involved in signaling pathways such as glycolysis, oxidative phosphorylation, spliceosome, thermogenesis, and cell cycle. The in vitro experiments confirmed the accuracy and reliability of bioinformatics analyses. We found that downregulation of USP22 could inhibit Sao-2 cell proliferation, migration, invasion, and induce apoptosis. Furthermore, downregulation of USP22 significantly reduced aerobic glycolysis levels in Sao-2 cells and inhibited the expression of key enzymes and transporters in aerobic glycolysis pathways such as HK2, PKM2, and GLUT1.

Conclusions

USP22 plays a critical role in the occurrence, development, and prognosis of osteosarcoma. USP22 could influence Sao-2 cell proliferation, apoptosis, migration, and invasion by regulating the glycolysis pathway, thereby promoting osteosarcoma progression. Therefore, USP22 may be a potential therapeutic target for the treatment of osteosarcoma.

The ubiquitous role of ubiquitination in lipid metabolism

Lipids are essential molecules that play key roles in cell physiology by serving as structural components, for storage of energy, and in signal transduction. Hence, efficient regulation and maintenance of lipid homeostasis are crucial for normal cellular and tissue function. In the past decade, increasing research has shown the importance of ubiquitination in regulating the stability of key players in different aspects of lipid metabolism. This review describes recent insights into the regulation of lipid metabolism by ubiquitin signaling, discusses how ubiquitination can be targeted in diseases characterized by lipid dysregulation, and identifies areas that require further research.

The natural compounds, Magnolol or Honokiol, promote adipose tissue browning and resist obesity through modulating PPARα/γ activity

Non-alcoholic fatty liver disease (NAFLD) is closely associated with the body's energy metabolism. A potential strategy to regulate energy metabolism, combat obesity, and reduce NAFLD is by enhancing adipocyte thermogenesis and increasing energy expenditure. In this study, our objective was to examine the effects of phenolic extracts derived from Magnolia officinalis on the regulation of NAFLD. Specifically, we investigated the impact of Magnolol or Honokiol treatment on high-fat diet (HFD)-induced obese C57BL6/J male mice. Firstly, we monitored energy metabolism, dissected tissues, and analyzed tissue sections. Additionally, we conducted experiments on HepG2 and primary adipocytes to gain insights into the roles of Magnolol or Honokiol. To further understand the effects of these compounds on related signaling pathways and marker genes, we performed molecular docking, dual-luciferase assays, and interfered with target genes. Our findings revealed that Magnolol or Honokiol activate the peroxisome proliferator activated receptor alpha (PPARα) signaling pathway, leading to the alleviation of NAFLD. This activation promotes fatty acid oxidation, reduces lipogenesis, and enhances the expression and secretion of FGF21. Notably, Fibroblast growth factor 21 (FGF21), secreted by the liver, plays a crucial role in improving communication between the liver and adipocytes while also promoting the browning of adipose tissue. Additionally, Magnolol or Honokiol activate the peroxisome proliferator activated receptor gamma (PPARγ) signaling pathway, resulting in increased uncoupling protein 1 (UCP1) expression, heightened heat production in adipose tissue, and anti-obesity. Therefore, Magnolol or Honokiol alleviate NAFLD, promote adipose tissue browning and resist obesity through dual activation of PPARα/γ.