De-ubiquitination of SAMHD1 by USP7 promotes DNA damage repair to overcome oncogenic stress and affect chemotherapy sensitivity

HUWE1-mediated ubiquitination and degradation of oxidative damage repair gene ATM maintains mitochondrial quality control system in lens epithelial cells

Mitochondrial dysfunction, resulting from a diminished oxidative damage repair capacity of mitochondrial DNA (mtDNA) in peripheral lens epithelial cells (LECs), is a key pathogenic mechanism in age-related cortical cataract (ARCC). This study aims to investigate the potential role of the E3 ligase HUWE1 and its ubiquitination substrate, the oxidative damage repair gene ATM, in the pathogenesis of ARCC. Our findings reveal that ATM protein expression is downregulated in human peripheral lens epithelial cells and the turbid cortex, correlating with increased expression of HUWE1. Overexpression of ATM is shown to repair damaged mtDNA, protect mitochondria in LECs from oxidative damage, inhibit mitochondrial fission, enhance mitochondrial biogenesis and mitophagy, and prevent LECs apoptosis. Conversely, overexpression of HUWE1 may negate the protective effects of ATM via the ubiquitination pathway, promote oxidative stress-induced mitochondrial damage, increase the expression of mitochondrial fission proteins Drp1/Fis1, lead to mitochondrial network fragmentation and LECs apoptosis. In a SD rat lens model ex vitro, the ATM inhibitor AZD0156 exacerbated lens opacity, whereas the mitochondrial fission inhibitor Mdivi-1 restored lens transparency. These results suggest that modulating key molecules involved in oxidative damage repair and mitochondrial fission pathways could enhance mitochondrial quality control, paving the way for the development of targeted molecular therapies for the prevention and treatment of ARCC.

USP7-Mediated ICAM1 Facilitates Lipopolysaccharide-Induced Human Pulmonary Microvascular Endothelial Cell Injury to Accelerate Pediatric Acute Respiratory Distress Syndrome

BACKGROUND

Intercellular cell adhesion molecule 1 (ICAM1) has been confirmed to be abnormally expressed in acute respiratory distress syndrome (ARDS) patients. However, its role and mechanism in pediatric ARDS process need further revealed.

METHODS

Serum samples were selected from pediatric ARDS patients and age-matched healthy individuals. Lipopolysaccharide (LPS)-induced human pulmonary microvascular endothelial cells (HPMECs) were used to mimic ARDS cell models. Cell proliferation and apoptosis were tested by cell counting kit 8 assay, EdU assay, and flow cytometry. Oxidative stress and inflammation were assessed by corresponding kits. M1 macrophage polarization was evaluated via measuring CD86 positive cell rate. The expression levels of ICAM1, ubiquitin-specific peptidase 7 (USP7), and NF-κB pathway-related markers were detected by quantitative real-time PCR and western blot. The interaction between USP7 and ICAM1 was analyzed by Co-IP assay.

RESULTS

LPS induced apoptosis, inflammation, oxidative stress, and M1 macrophage polarization, while suppressed proliferation in HPMECs. ICAM1 was upregulated in pediatric ARDS patients, and its knockdown alleviated HPMEC injury induced by LPS. USP7 positively regulated ICAM1 protein expression through deubiquitination. USP7 overexpression aggravated LPS-induced HPMEC apoptosis, inflammation, oxidative stress, and M1 macrophage polarization. Besides, ICAM1 upregulation could eliminate the inhibitory effect of USP7 knockdown on LPS-induced HPMEC injury. In addition, USP7 activated NF-κB pathway by promoting ICAM1 expression.

CONCLUSION

USP7-mediated ICAM1 upregulation could promote LPS-induced HPMEC injury by activating NF-κB pathway, which provided a new idea for the treatment of pediatric ARDS.

Unraveling the role of deubiquitinating enzymes on cisplatin resistance in several cancers

The use of platinum-based drugs in cancer treatment is one of the most common methods in chemotherapy. Especially, cisplatin induces cell death by interrupting DNA synthesis by binding to the DNA bases, thereby leading to the apoptosis via multiple pathways. However, the major hurdle in chemotherapy is drug resistance. To overcome drug resistance, the ubiquitin-proteasome system (UPS) has emerged as a potential therapeutic target. The UPS is a pivotal signaling pathway that regulates the majority of cellular proteins by attaching ubiquitin to substrates, leading to proteasomal degradation. Conversely, deubiquitinating enzymes (DUBs) remove tagged ubiquitin from the substrate and inhibit degradation, thereby maintaining proteostasis. Recently, studies have been conducted to identify the substrates of DUBs and investigated the cellular mechanisms, and now the development of therapeutics using DUB inhibitors is in clinical trials. However, the mechanism of the DUB response to cisplatin remains still unclear. In this review, we summarize the research reported on the function of DUBs responding to cisplatin.

METTL14 Promotes the Osteogenic Differentiation of Human Bone Marrow Stromal Cells via m6A-Dependent Stabilization of USP7 mRNA

Osteoporosis (OP) is a common clinical bone disease that can cause a high incidence of non-stress fractures and is one of the main degenerative diseases that endangers the health and life of middle-aged and older women. The mechanism underlying the abnormal differentiation and function of human bone marrow stem cells (hBMSCs) remains to be elucidated. Cell proliferation and differentiation were determined using 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay, alkaline phosphatase (ALP) staining, and Alizarin Red Staining. The interaction between insulin-like growth factor 2 mRNA-binding protein 2 (IGF2BP2) and ubiquitin-specific protease 7 (USP7) was predicted and validated using bioinformatics approaches, luciferase assays, RNA immunoprecipitation (RIP), and immunoprecipitation (IP). Actinomycin D treatment was used to test the stability of mRNA in the various groups. Methyltransferase-like 14 (METTL14) expression was increased in osteogenic differentiation medium-induced hBSMCs and was associated with enhanced osteogenic differentiation. METTL14 regulated the expression USP7 by modulating its N6-methyladenosine (m6A) level. IGF2BP2 exerted an m6A-dependent effect on USP7 mRNA stability and USP7 increased sirtuin 1 (SIRT1) expression in hBMSCs by enhancing SIRT1 deubiquitination. METTL14 stimulated the osteogenic differentiation of hBMSCs through the m6A-IGF2BP2-USP7 pathway and promoted hBMSCs osteogenic development via SIRT1-Bmi1 signaling. METTL14 stimulated the osteogenic differentiation of hBMSCs by stabilizing USP7 mRNA in an m6A-dependent manner. USP7 was also stabilized by IGF2BP2 and it regulated downstream SIRT1-Bmi1 signaling.

New insights into SUMOylation and NEDDylation in fibrosis

Fibrosis is the outcome of any abnormal tissue repair process that results in normal tissue replacement with scar tissue, leading to persistent tissue damage and cellular injury. During the process of fibrosis, many cytokines and chemokines are involved, and their activities are controlled by post-translational modifications, especially SUMOylation and NEDDylation. Both these modifications entail a three-step process of activation, conjugation, and ligation that involves three kinds of enzymes, namely, E1 activating, E2 conjugating, and E3 ligase enzymes. SUMOylation participates in organ fibrosis by modulating FXR, PML, TGF-β receptor I, Sirt3, HIF-1α, and Sirt1, while NEDDylation influences organ fibrosis by regulating cullin3, NIK, SRSF3, and UBE2M. Further investigations exhibit the therapeutic potentials of SUMOylation/NEDDylation activators and inhibitors against organ fibrosis, especially ginkgolic acid in SUMOylation and MLN4924 in NEDDylation. These results demonstrate the therapeutic effects of SUMOylation and NEDDylation against organ fibrosis and highlight their activators as well as inhibitors as potential candidates. In the future, deeper investigations of SUMOylation and NEDDylation are needed to identify novel substrates against organ fibrosis; moreover, clinical investigations are needed to determine the therapeutic effects of their activators and inhibitors that can benefit patients. This review highlights that SUMOylation and NEDDylation function as potential therapeutic targets for organ fibrosis.

The Role and Mechanism of Deubiquitinase USP7 in Tumor-Associated Inflammation

Deubiquitinating enzymes are a class of proteases that remove ubiquitin tags from proteins, thereby controlling protein stability and function. Tumor inflammation arises from interactions between tumor cells and their microenvironment, which trigger an inflammatory response. The deubiquitinating enzyme USP7 plays a central role in this process. Research suggests that USP7 may modulate various signaling pathways related to inflammatory responses through its deubiquitinating activity, thereby influencing tumor development and progression, including regulating T cell immune activity, improving macrophage anti-tumor activity, and regulating NF-κB signal pathways. Overall, describing the role and mechanism of USP7 in the tumor inflammatory response is of great importance for elucidating the regulatory mechanism of tumor inflammation and developing new therapeutic strategies. This article mainly reviews the structure, function, role, and mechanism of USP7 in the tumor inflammation response.

USP7 alleviates neuronal inflammation and apoptosis in spinal cord injury via deubiquitinating NRF1/KLF7 axis

BACKGROUND

Ubiquitin-specific protease 7 (USP7) has been found to be associated with motor function recovery after spinal cord injury (SCI). Therefore, its role and mechanism in SCI process need further exploration.

METHODS

SCI rat models were established via performing laminectomy at the T9-T11 spinal vertebrae and cutting spinal cord tissues. SCI cell models were constructed by inducing PC12 cells with lipopolysaccharide (LPS). The protein levels of USP7, nuclear respiratory factor 1 (NRF1), Krüppel-like factor 7 (KLF7) and apoptosis-related markers were detected by western blot. Cell viability and apoptosis were tested by cell counting kit-8 assay and flow cytometry. The contents of inflammatory factors were examined using ELISA. The interaction between NRF1 and USP7 or KLF7 was analyzed by co-immunoprecipitation assay, chromatin immunoprecipitation assay and dual-luciferase reporter assay, respectively.

RESULTS

USP7 was downregulated in SCI rat models and LPS-induced PC12 cells. Overexpressed USP7 promoted viability, while repressed apoptosis and inflammation in LPS-induced PC12 cells. USP7 could stabilize NRF1 protein expression via deubiquitination, and NRF1 knockdown reversed the protective effect of USP7 against LPS-induced PC12 cell injury. NRF1 is bound to KLF7 promoter to enhance its transcription. NRF1 overexpression inhibited LPS-induced PC12 cell inflammation and apoptosis via increasing KLF7 expression.

CONCLUSION

USP7 alleviated inflammation and apoptosis in LPS-induced PC12 cells via NRF1/KLF7 axis, indicating that targeting of USP7/NRF1/KLF7 axis might be a promising treatment strategy for SCI.

Understanding the interplay between dNTP metabolism and genome stability in cancer

The size and composition of the intracellular DNA precursor pool is integral to the maintenance of genome stability, and this relationship is fundamental to our understanding of cancer. Key aspects of carcinogenesis, including elevated mutation rates and induction of certain types of DNA damage in cancer cells, can be linked to disturbances in deoxynucleoside triphosphate (dNTP) pools. Furthermore, our approaches to treat cancer heavily exploit the metabolic interplay between the DNA and the dNTP pool, with a long-standing example being the use of antimetabolite-based cancer therapies, and this strategy continues to show promise with the development of new targeted therapies. In this Review, we compile the current knowledge on both the causes and consequences of dNTP pool perturbations in cancer cells, together with their impact on genome stability. We outline several outstanding questions remaining in the field, such as the role of dNTP catabolism in genome stability and the consequences of dNTP pool expansion. Importantly, we detail how our mechanistic understanding of these processes can be utilised with the aim of providing better informed treatment options to patients with cancer.

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.

Molecular characterization, clinical value, and cancer-immune interactions of genes related to disulfidptosis and ferroptosis in colorectal cancer

BACKGROUND

This research strived to construct a new signature utilizing disulfidptosis-related ferroptosis (SRF) genes to anticipate response to immunotherapy, prognosis, and drug sensitivity in individuals with colorectal cancer (CRC).

METHODS

The data for RNA sequencing as well as corresponding clinical information of individuals with CRC, were extracted from The Cancer Genome Atlas (TCGA) dataset. SRF were constructed with the help of the random forest (RF), least absolute shrinkage and selection operator (LASSO), and stepwise regression algorithms. To validate the SRF model, we applied it to an external cohort, GSE38832. Prognosis, immunotherapy response, drug sensitivity, molecular functions of genes, and somatic mutations of genes were compared across the high- and low-risk groups (categories). Following this, all statistical analyses were conducted with the aid of the R (version 4.23) software and various packages of the Cytoscape (version 3.8.0) tool.

RESULTS

SRF was developed based on five genes (ATG7, USP7, MMD, PLIN4, and THDC2). Both univariate and multivariate Cox regression analyses established SRF as an independent, prognosis-related risk factor. Individuals from the high-risk category had a more unfavorable prognosis, elevated tumor mutational burden (TMB), and significant immunosuppressive status. Hence, they might have better outcomes post-immunotherapy and might benefit from the administration of pazopanib, lapatinib, and sunitinib.

CONCLUSION

In conclusion, SRF can act as a new biomarker for prognosis assessment. Moreover, it is also a good predictor of drug sensitivity and immunotherapy response in CRC but should undergo optimization before implementation in clinical settings.

Drug resistance mechanisms and treatment strategies mediated by Ubiquitin-Specific Proteases (USPs) in cancers: new directions and therapeutic options

Drug resistance represents a significant obstacle in cancer treatment, underscoring the need for the discovery of novel therapeutic targets. Ubiquitin-specific proteases (USPs), a subclass of deubiquitinating enzymes, play a pivotal role in protein deubiquitination. As scientific research advances, USPs have been recognized as key regulators of drug resistance across a spectrum of treatment modalities, including chemotherapy, targeted therapy, immunotherapy, and radiotherapy. This comprehensive review examines the complex relationship between USPs and drug resistance mechanisms, focusing on specific treatment strategies and highlighting the influence of USPs on DNA damage repair, apoptosis, characteristics of cancer stem cells, immune evasion, and other crucial biological functions. Additionally, the review highlights the potential clinical significance of USP inhibitors as a means to counter drug resistance in cancer treatment. By inhibiting particular USP, cancer cells can become more susceptible to a variety of anti-cancer drugs. The integration of USP inhibitors with current anti-cancer therapies offers a promising strategy to circumvent drug resistance. Therefore, this review emphasizes the importance of USPs as viable therapeutic targets and offers insight into fruitful directions for future research and drug development. Targeting USPs presents an effective method to combat drug resistance across various cancer types, leading to enhanced treatment strategies and better patient outcomes.

ER Stress-Activated HSF1 Governs Cancer Cell Resistance to USP7 Inhibitor-Based Chemotherapy through the PERK Pathway

Ubiquitin-specific protease 7 inhibitors (USP7i) are considered a novel class of anticancer drugs. Cancer cells occasionally become insensitive to anticancer drugs, known as chemoresistance, by acquiring multidrug resistance, resulting in poor clinical outcomes in patients with cancer. However, the chemoresistance of cancer cells to USP7i (P22077 and P5091) and mechanisms to overcome it have not yet been investigated. In the present study, we generated human cancer cells with acquired resistance to USP7i-induced cell death. Gene expression profiling showed that heat stress response (HSR)- and unfolded protein response (UPR)-related genes were largely upregulated in USP7i-resistant cancer cells. Biochemical studies showed that USP7i induced the phosphorylation and activation of heat shock transcription factor 1 (HSF1), mediated by the endoplasmic reticulum (ER) stress protein kinase R-like ER kinase (PERK) signaling pathway. Inhibition of HSF1 and PERK significantly sensitized cancer cells to USP7i-induced cytotoxicity. Our study demonstrated that the ER stress-PERK axis is responsible for chemoresistance to USP7i, and inhibiting PERK is a potential strategy for improving the anticancer efficacy of USP7i.

RNA methylation, homologous recombination repair and therapeutic resistance

Homologous recombination (HR) repair of DNA double-strand breaks (DSBs) is critical for maintaining genomic integrity and stability. Defects in HR increase the risk of tumorigenesis. However, many human tumors exhibit enhanced HR repair capabilities, consequently endowing tumor cells with resistance to DNA-damaging chemotherapy and radiotherapy. This review summarizes the role of RNA methylation in HR repair and therapeutic resistance in human tumors. We also analyzed the interactions between RNA methylation and other HR-modulating modifications including histone acetylation, histone deacetylation, ubiquitination, deubiquitination, protein arginine methylation, and gene transcription. This review proposes that targeting RNA methylation is a promising approach to overcoming HR-mediated therapeutic resistance.