Ubiquitination and deubiquitination: Implications on cancer therapy

The role of ubiquitination in health and disease

Ubiquitination is an enzymatic process characterized by the covalent attachment of ubiquitin to target proteins, thereby modulating their degradation, transportation, and signal transduction. By precisely regulating protein quality and quantity, ubiquitination is essential for maintaining protein homeostasis, DNA repair, cell cycle regulation, and immune responses. Nevertheless, the diversity of ubiquitin enzymes and their extensive involvement in numerous biological processes contribute to the complexity and variety of diseases resulting from their dysregulation. The ubiquitination process relies on a sophisticated enzymatic system, ubiquitin domains, and ubiquitin receptors, which collectively impart versatility to the ubiquitination pathway. The widespread presence of ubiquitin highlights its potential to induce pathological conditions. Ubiquitinated proteins are predominantly degraded through the proteasomal system, which also plays a key role in regulating protein localization and transport, as well as involvement in inflammatory pathways. This review systematically delineates the roles of ubiquitination in maintaining protein homeostasis, DNA repair, genomic stability, cell cycle regulation, cellular proliferation, and immune and inflammatory responses. Furthermore, the mechanisms by which ubiquitination is implicated in various pathologies, alongside current modulators of ubiquitination are discussed. Enhancing our comprehension of ubiquitination aims to provide novel insights into diseases involving ubiquitination and to propose innovative therapeutic strategies for clinical conditions.

KIFC1 depends on TRIM37-mediated ubiquitination of PLK4 to promote centrosome amplification in endometrial cancer

Endometrial cancer (EC), as one of the most common cancers, severely threatens female reproductive health. Our previous study has shown that Kinesin family member C1 (KIFC1) played crucial roles in the progression of EC. In addition, abnormal centrosome amplification, which was reported to be partially regulated by KIFC1, usually occurred in different cancers. However, whether KIFC1 promoted EC through centrosome amplification and the potential mechanism remain to be revealed. The present study demonstrated that overexpressed KIFC1, which exhibited a worse prognosis, had a positive correlation with an increased number of centrosomes in human EC samples. In addition, KIFC1 overexpression in EC cells prompted centrosome amplification, chromosomal instability, and cell cycle progression. Moreover, we demonstrated that KIFC1 inhibited E3 ubiquitin-protein ligase TRIM37 to maintain the stability of PLK4 by reducing its ubiquitination degradation, and finally promoting centrosome amplification and EC progression in vitro. Finally, the contributing role of KIFC1 and the inhibitory effect of TRIM37 on EC development and metastasis was verified in a nude mouse xenograft model. Our study elucidated that KIFC1 depends on TRIM37-mediated reduced ubiquitination degradation of PLK4 to promote centrosome amplification and EC progression, thus providing a potential prognostic marker and promising therapeutic target for EC in the future.

HECTD2 as a target for veratric acid in the regulation of ferroptosis in renal cell carcinoma

Function of HECTD2 in renal cell carcinoma malignant progression is undefined. Molecular mechanism behind anti-cancer effects of veratric acid (VA) from traditional Chinese medicine (TCM) is underexplored. The Cancer Genome Atlas was leveraged to study HECTD2 expression in renal cell carcinoma and its relationship with histological grading. Kaplan-Meier survival analysis was performed. HECTD2 expression was detected in cancer cells and tissues via qRT-PCR and immunohistochemistry. GPX4 and SLC7A11 expression in tumor samples with high or low HECTD2 expression was examined by immunohistochemistry, cell viability by CCK8, cell proliferation by colony formation assay, lipid ROS and mitochondrial superoxide levels by flow cytometry, Fe2+ and MDA content by assay kits, and GPX4 and SLC7A11 proteins by western blot. SeeSAR software screened TCM small molecule compounds with highest affinity to HECTD2, confirmed with cellular thermal shift assay. VA IC50 was measured by CCK8. Xenograft model was developed and treated with VA. Tumor size and weight were monitored, with immunohistochemistry to detect HECTD2 expression in tumors and assess ferroptosis-related markers. HECTD2 was overexpressed in tumor tissues and cells, which positively correlated with histological grading. HECTD2 depletion inhibited cell vitality and proliferation, raised intracellular lipid ROS, mitochondrial superoxide, Fe2+, and MDA. HECTD2 was a target with highest VA affinity. In vitro and vivo experiments concurred that VA treatment hindered malignancy of renal cell carcinoma and enhanced its susceptibility to ferroptosis. HECTD2 supports ferroptosis resistance in renal cell carcinoma, but VA, through its targeting of HECTD2, initiates ferroptosis, showcasing its anti-cancer efficacy.

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.

UBTD1 is a potential prognostic biomarker in colorectal cancer

Colorectal cancer (CRC) is a complex malignancy with poorly understood molecular mechanisms, necessitating the identification of genetic markers. Although Ubiquitin domain-containing protein 1 (UBTD1) has received significant attention in the study of human cancers, its specific role in CRC is yet to be fully clarified. This study sought to examine how UBTD1 expression was associated with various clinical and pathological characteristics of CRC, and to determine its prognostic significance and biological function, utilizing data from clinical samples and large-scale databases. Notably, UBTD1 expression was found to be upregulated in CRC, resulting in decreased survival rates and unfavorable clinical characteristics such as advanced T, N, and pathological stages. The findings of the multivariate Cox regression analysis illustrated that UBTD1 expression upregulation is a significant independent marker of unfavorable outcomes in CRC patients. An examination of the functional enrichment of UBTD1 and the genes it co-expresses indicated that it could serve as an oncogene by modulating the expression of genes implicated in crucial tumorigenesis pathways and functions. Additionally, immune cell infiltration analysis suggested a link between UBTD1 levels and various immune cells, particularly macrophages. In conclusion, the use of UBTD1 as a biomarker for both the prognosis and diagnosis of CRC has promising prospects for further investigation and therapeutic approaches.

CD28 co-stimulation: novel insights and applications in cancer immunotherapy

Substantial progress in understanding T cell signalling, particularly with respect to T cell co-receptors such as the co-stimulatory receptor CD28, has been made in recent years. This knowledge has been instrumental in the development of innovative immunotherapies for patients with cancer, including immune checkpoint blockade antibodies, adoptive cell therapies, tumour-targeted immunostimulatory antibodies, and immunostimulatory small-molecule drugs that regulate T cell activation. Following the failed clinical trial of a CD28 superagonist antibody in 2006, targeted CD28 agonism has re-emerged as a technologically viable and clinically promising strategy for cancer immunotherapy. In this Review, we explore recent insights into the molecular functions and regulation of CD28. We describe how CD28 is central to the success of current cancer immunotherapies and examine how new questions arising from studies of CD28 as a clinical target have enhanced our understanding of its biological role and may guide the development of future therapeutic strategies in oncology.

PRDM1 promotes the ferroptosis and immune escape of thyroid cancer by regulating USP15-mediated SELENBP1 deubiquitination

BACKGROUND

The deubiquitinating enzyme Ubiquitin-specific peptidase 15 (USP15) is upregulated in various cancers and promotes tumor progression by increasing the expression of several oncogenes. This project is designed to explore the role and mechanism of USP15 in thyroid cancer (TC) progression.

METHODS

Selenium-binding protein 1 (SELENBP1), USP15, CCL2/5, CXCL10/11, IL-4, and TGF-β1 mRNA levels were detected using real-time quantitative polymerase chain reaction (RT-qPCR). SELENBP1, USP15, GPX4, IL-10, Arg-1, Granzyme B, TNF-α, and PR domain zinc finger protein 1 (PRDM1) protein levels were examined by western blot assay. Fe+ level, malondialdehyde (MDA), and lipid-ROS levels were determined using special kits. The proportion of CD11b+CD206+ positive cells was detected using a flow cytometry assay. The role of SELENBP1 on TC cell growth was examined using a xenograft tumor model in vivo. After GeneMANIA prediction, the interaction between USP15 and SELENBP1 was verified using Co-immunoprecipitation (CoIP) assay. The binding between PRDM1 and USP15 promoter was predicted by JASPAR and validated using Chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays.

RESULTS

SELENBP1 was increased in TC subjects and cell lines, and its knockdown repressed TC cell proliferation, migration, invasion, immune escape, and induced ferroptosis in vitro, as well as blocked tumor growth in vivo. In mechanism, USP15 interacted with SELENBP1 and maintained its stabilization by removing ubiquitin. Meanwhile, the upregulation of USP15 was induced by the transcription factor PRDM1.

CONCLUSION

USP15 transcriptionally mediated by PRDM1 might boost TC cell malignant behaviors through deubiquitinating SELENBP1, providing a promising therapeutic target for TC treatment.

The future of cancer treatment: combining radiotherapy with immunotherapy

Radiotherapy (RT) and immunotherapy (IT) are the powerful tools for cancer treatment which act through the stimulation of immune response, and evidence suggest that combinatorial actions of these therapies may augment each other's beneficial effect through complex synergistic mechanisms. These molecular strategies are designed to target rapidly dividing cancer cells by either directly or indirectly inducing DNA damage. However, when cells detect DNA damage, they activate a range of signalling pathways known as the DNA damage response (DDR) to repair. Strategies are being developed to interfere with the DDR pathways in cancer cells to ensure their damage-induced degeneration. The stability of a cell's genetic material is largely dependent on the efficacy of DNA repair and therefore, an in-depth understanding of DNA damages and repair mechanism(s) in cancer cells is important to develop a promising therapeutic strategies for ensuring the efficacy of damage-induced tumor cell death. In recent years, a wide range of small molecule drugs have been developed which are currently being employed to combat the DNA repair deficiencies associated with tumor cells. Sequential or concurrent use of these two modalities significantly enhances the anti-tumor response, however with a concurrent probability of increased incidence of symptomatic adverse effects. With advent of newer IT agents, and administration of higher doses of radiation per fraction, such effects are more difficult to predict owing to the paucity of randomized trial data. It is well established that anti cytotoxic-T-lymphocyte-associated antigen 4 (CTLA-4), anti- Programmed cell death protein 1(PD-1), anti-Programmed cell death one ligand 1 (PD-L1) can be safely administered with RT and many studies have demonstrated survival benefit with such combination for patients with metastatic malignancy. However, the biology of radioimmunotherapy (RT/IT) is still an open area where research need to be focused to determine optimum dosage specially the interaction of the RT/IT pathways to determine optimum dosing schedule. In the current article we have summarised the possible intracellular immunological events that might be triggered when RT and IT modalities are combined with the DDR antagonists and highlighted present clinical practices, outcome, and toxicity profile of this novel treatment strategy.

USP3 promotes cisplatin resistance in non-small cell lung cancer cells by suppressing ACOT7-regulated ferroptosis

This study aims to investigate the role and mechanism of ubiquitin-specific protease 3 (USP3) in cisplatin (DDP) in non-small cell lung cancer (NSCLC). USP3 expression in NSCLC cells was detected using reverse transcription quantitative PCR and Western blot. DDP-resistant cells were constructed and cell counting kit-8 assay determined the IC 50 of cells to DDP. USP3 expression was silenced in DDP-resistant cells, followed by detection of cell proliferation by clone formation assay, iron ion contents, ROS, MDA, and GSH levels by kits, GPX4 and ACSL4 protein expressions by Western blot. The binding between USP3 and ACOT7 was analyzed using Co-IP, and the ubiquitination level of ACOT7 was measured. USP3 and ACOT7 were highly expressed in NSCLC cells and further increased in drug-resistant cells. USP3 silencing reduced the IC 50 of cells to DDP and diminished the number of cell clones. Moreover, USP3 silencing suppressed GSH and GPX4 levels, upregulated iron ion contents, ROS, MDA, and ACSL4 levels, and facilitated ferroptosis. Mechanistically, USP3 upregulated ACOT7 protein expression through deubiquitination. ACOT7 overexpression alleviated the promoting effect of USP7 silencing on ferroptosis in NSCLC cells and enhanced DDP resistance. To conclude, USP3 upregulated ACOT7 protein expression through deubiquitination, thereby repressing ferroptosis in NSCLC cells and enhancing DDP resistance.

BHLHE41 inhibits bladder cancer progression via regulation of PYCR1 stability and thus inactivating PI3K/AKT signaling pathway

BACKGROUND

The basic helix-loop-helix family member e41 (BHLHE41) is frequently dysregulated in tumors and plays a crucial role in malignant progression of various cancers. Nevertheless, its specific function and underlying mechanism in bladder cancer (BCa) remain largely unexplored.

METHODS

The expression levels of BHLHE41 in BCa tissues and cells were examined by qRT-PCR and western blot assays. BCa cells stably knocking down or overexpressing BHLHE41 were constructed through lentivirus infection. The changes of cell proliferation, cell cycle distribution, migration, and invasion were detected by CCK-8, flow cytometry, wound healing, transwell invasion assays, respectively. The expression levels of related proteins were detected by western blot assay. The interaction between BHLHE41 and PYCR1 was explored by co-immunoprecipitation analysis.

RESULTS

In this study, we found that BHLHE41 was lowly expressed in bladder cancer tissues and cell lines, and lower expression of BHLHE41 was associated with poor overall survival in bladder cancer patients. Functionally, by manipulating the expression of BHLHE41, we demonstrated that overexpression of BHLHE41 significantly retarded cell proliferation, migration, invasion, and induced cell cycle arrest in bladder cancer through various in vitro and in vivo experiments, while silence of BHLHE41 caused the opposite effect. Mechanistically, we showed that BHLHE41 directly interacted with PYCR1, decreased its stability and resulted in the ubiquitination and degradation of PYCR1, thus inactivating PI3K/AKT signaling pathway. Rescue experiments showed that the effects induced by BHLHE41 overexpression could be attenuated by further upregulating PYCR1.

CONCLUSION

BHLHE41 might be a useful prognostic biomarker and a tumor suppressor in bladder cancer. The BHLHE41/PYCR1/PI3K/AKT axis might be a potential therapeutic target for bladder cancer intervention.

NEDD4 and NEDD4L: Ubiquitin Ligases Closely Related to Digestive Diseases

Protein ubiquitination is an enzymatic cascade reaction and serves as an important protein post-translational modification (PTM) that is involved in the vast majority of cellular life activities. The key enzyme in the ubiquitination process is E3 ubiquitin ligase (E3), which catalyzes the binding of ubiquitin (Ub) to the protein substrate and influences substrate specificity. In recent years, the relationship between the subfamily of neuron-expressed developmental downregulation 4 (NEDD4), which belongs to the E3 ligase system, and digestive diseases has drawn widespread attention. Numerous studies have shown that NEDD4 and NEDD4L of the NEDD4 family can regulate the digestive function, as well as a series of related physiological and pathological processes, by controlling the subsequent degradation of proteins such as PTEN, c-Myc, and P21, along with substrate ubiquitination. In this article, we reviewed the appropriate functions of NEDD4 and NEDD4L in digestive diseases including cell proliferation, invasion, metastasis, chemotherapeutic drug resistance, and multiple signaling pathways, based on the currently available research evidence for the purpose of providing new ideas for the prevention and treatment of digestive diseases.

Ubiquitin-specific proteases: From biological functions to potential therapeutic applications in gastric cancer

Deubiquitination, a post-translational modification regulated by deubiquitinases, is essential for cancer initiation and progression. Ubiquitin-specific proteases (USPs) are essential elements of the deubiquitinase family, and are overexpressed in gastric cancer (GC). Through the regulation of several signaling pathways, such as Wnt/β-Catenin and nuclear factor-κB signaling, and the promotion of the expression of deubiquitination- and stabilization-associated proteins, USPs promote the proliferation, metastasis, invasion, and epithelial-mesenchymal transition of GC. In addition, the expression of USPs is closely related to clinicopathological features, patient prognosis, and chemotherapy resistance. USPs therefore could be used as prognostic biomarkers. USP targeting small molecule inhibitors have demonstrated strong anticancer activity. However, they have not yet been tested in the clinic. This article provides an overview of the latest fundamental research on USPs in GC, aiming to enhance the understanding of how USPs contribute to GC progression, and identifying possible targets for GC treatment to improve patient survival.

Programmed Death Ligand 1 Regulatory Crosstalk with Ubiquitination and Deubiquitination: Implications in Cancer Immunotherapy

Programmed death ligand 1 (PD-L1) plays a pivotal role in cancer immune evasion and is a critical target for cancer immunotherapy. This review focuses on the regulation of PD-L1 through the dynamic processes of ubiquitination and deubiquitination, which are crucial for its stability and function. Here, we explored the intricate mechanisms involving various E3 ubiquitin ligases and deubiquitinating enzymes (DUBs) that modulate PD-L1 expression in cancer cells. Specific ligases are discussed in detail, highlighting their roles in tagging PD-L1 for degradation. Furthermore, we discuss the actions of DUBs that stabilize PD-L1 by removing ubiquitin chains. The interplay of these enzymes not only dictates PD-L1 levels but also influences cancer progression and patient response to immunotherapies. Furthermore, we discuss the therapeutic implications of targeting these regulatory pathways and propose novel strategies to enhance the efficacy of PD-L1/PD-1-based therapies. Our review underscores the complexity of PD-L1 regulation and its significant impact on the tumor microenvironment and immunotherapy outcomes.