USP10 as a Potential Therapeutic Target in Human Cancers

FOXP4-AS1 promotes CD8+ T cell exhaustion and esophageal cancer immune escape through USP10-stabilized PD-L1

Esophageal cancer (EC) is the 9th most frequently diagnosed malignancy globally with unfavorable prognosis. Immune escape is one of the principal factors leading to poor survival, however, the mechanism underlying immune escape remains largely uninvestigated. The xenograft mouse model and EC cell-CD8+ cytotoxic T lymphocytes (CTLs) co-culture system were established. Immunohistochemistry, qRT-PCR or western blot were employed to detect the levels of long non-coding RNA (lncRNA) FOXP4-AS1, PD-L1, USP10 and other molecules. The abundance of T cells, cytokine production and cell apoptosis were monitored by flow cytometry. The viability of CTLs was assessed by Trypan blue staining. The binding between FOXP4-AS1 and USP10 was validated by RNA pull-down assay, and the interaction between USP10 and PD-L1, as well as the ubiquitination of PD-L1, were detected by co-immunoprecipitation. The elevation of FOXP4-AS1 in EC was associated with decreased CTL abundance, and upregulated PD-L1 facilitated CTL apoptosis in EC. FOXP4-AS1 accelerated EC tumor growth by decreasing the abundance of tumor infiltrating CTLs in vivo. FOXP4-AS1 inhibited the viability of CTLs and facilitated the cytotoxicity and exhaustion of CTLs. In Kyse 450 cell-CTL co-culture system, FOXP4-AS1 suppressed the viability and abundance of CTLs, and inhibited EC cell apoptosis via PD-L1. Mechanistically, FOXP4-AS1 regulated the ubiquitination of PD-L1 through deubiquitinating enzyme USP10. FOXP4-AS1 promoted CTL exhaustion and EC immune escape through USP10-stabilized PD-L1. HIGHLIGHTS: PD-L1 facilitated CD8+ T cell apoptosis in EC. Upregulated FOXP4-AS1 promoted EC tumor growth by inhibiting the viability and facilitating the cytotoxicity and exhaustion of tumor infiltrating CD8+ T cells. FOXP4-AS1 suppressed the viability and abundance of CD8+ T cells through USP10-mediated deubiquitination of PD-L1.

Targeting autophagy drug discovery: Targets, indications and development trends

Autophagy plays a vital role in sustaining cellular homeostasis and its alterations have been implicated in the etiology of many diseases. Drugs development targeting autophagy began decades ago and hundreds of agents were developed, some of which are licensed for the clinical usage. However, no existing intervention specifically aimed at modulating autophagy is available. The obstacles that prevent drug developments come from the complexity of the actual impact of autophagy regulators in disease scenarios. With the development and application of new technologies, several promising categories of compounds for autophagy-based therapy have emerged in recent years. In this paper, the autophagy-targeted drugs based on their targets at various hierarchical sites of the autophagic signaling network, e.g., the upstream and downstream of the autophagosome and the autophagic components with enzyme activities are reviewed and analyzed respectively, with special attention paid to those at preclinical or clinical trials. The drugs tailored to specific autophagy alone and combination with drugs/adjuvant therapies widely used in clinical for various diseases treatments are also emphasized. The emerging drug design and development targeting selective autophagy receptors (SARs) and their related proteins, which would be expected to arrest or reverse the progression of disease in various cancers, inflammation, neurodegeneration, and metabolic disorders, are critically reviewed. And the challenges and perspective in clinically developing autophagy-targeted drugs and possible combinations with other medicine are considered in the review.

Stabilization of MOF (KAT8) by USP10 promotes esophageal squamous cell carcinoma proliferation and metastasis through epigenetic activation of ANXA2/Wnt signaling

Dysregulation of MOF (also known as MYST1, KAT8), a highly conserved H4K16 acetyltransferase, plays important roles in human cancers. However, its expression and function in esophageal squamous cell carcinoma (ESCC) remain unknown. Here, we report that MOF is highly expressed in ESCC tumors and predicts a worse prognosis. Depletion of MOF in ESCC significantly impedes tumor growth and metastasis both in vitro and in vivo, whereas ectopic expression of MOF but not catalytically inactive mutant (MOF-E350Q) promotes ESCC progression, suggesting that MOF acetyltransferase activity is crucial for its oncogenic activity. Further analysis reveals that USP10, a deubiquitinase highly expressed in ESCC, binds to and deubiquitinates MOF at lysine 410, which protects it from proteosome-dependent protein degradation. MOF stabilization by USP10 promotes H4K16ac enrichment in the ANXA2 promoter to stimulate ANXA2 transcription in a JUN-dependent manner, which subsequently activates Wnt/β-Catenin signaling to facilitate ESCC progression. Our findings highlight a novel USP10/MOF/ANXA2 axis as a promising therapeutic target for ESCC.

The role of ubiquitination and deubiquitination in PI3K/AKT/mTOR pathway: A potential target for cancer therapy

The PI3K/AKT/mTOR pathway controls key cellular processes, including proliferation and tumor progression, and abnormally high activation of this pathway is a hallmark in human cancers. The post-translational modification, such as Ubiquitination and deubiquitination, fine-tuning the protein level and the activity of members in this pathway play a pivotal role in maintaining normal physiological process. Emerging evidence show that the unbalanced ubiquitination/deubiquitination modification leads to human diseases via PI3K/AKT/mTOR pathway. Therefore, a comprehensive understanding of the ubiquitination/deubiquitination regulation of PI3K/AKT/mTOR pathway may be helpful to uncover the underlying mechanism and improve the potential treatment of cancer via targeting this pathway. Herein, we summarize the latest research progress of ubiquitination and deubiquitination of PI3K/AKT/mTOR pathway, systematically discuss the associated crosstalk between them, as well as focus the clinical transformation via targeting ubiquitination process.

Deubiquitinases in cancer

Ubiquitination is an essential regulator of most, if not all, signalling pathways, and defects in cellular signalling are central to cancer initiation, progression and, eventually, metastasis. The attachment of ubiquitin signals by E3 ubiquitin ligases is directly opposed by the action of approximately 100 deubiquitinating enzymes (DUBs) in humans. Together, DUBs and E3 ligases coordinate ubiquitin signalling by providing selectivity for different substrates and/or ubiquitin signals. The balance between ubiquitination and deubiquitination is exquisitely controlled to ensure properly coordinated proteostasis and response to cellular stimuli and stressors. Not surprisingly, then, DUBs have been associated with all hallmarks of cancer. These relationships are often complex and multifaceted, highlighted by the implication of multiple DUBs in certain hallmarks and by the impact of individual DUBs on multiple cancer-associated pathways, sometimes with contrasting cancer-promoting and cancer-inhibiting activities, depending on context and tumour type. Although it is still understudied, the ever-growing knowledge of DUB function in cancer physiology will eventually identify DUBs that warrant specific inhibition or activation, both of which are now feasible. An integrated appreciation of the physiological consequences of DUB modulation in relevant cancer models will eventually lead to the identification of patient populations that will most likely benefit from DUB-targeted therapies.

USP10 promotes intrahepatic cholangiocarcinoma cell survival and stemness via SNAI1 deubiquitination

Cancer cell stemness contributes significantly to intrahepatic cholangiocarcinoma (ICC) progression. However, the roles of deubiquitinating enzymes (DUBs) in ICC modulation are poorly understood. Ubiquitin specific peptidase 10 (USP10) was highly expressed in ICC spheres. The interaction between USP10 and snail family transcriptional repressor 1 (SNAI1) reduced the polyubiquitination of the SNAI1 protein and stabilized the SNAI1 protein. USP10 knockdown in RBE cells inhibited cell proliferation, promoted cell apoptosis and decreased the diameter of the formed spheres and the expression levels of CD44, EpCAM, OCT4 and SOX2. SNAI1 overexpression alleviated the effect of USP10 knockdown in RBE cells. In addition, the knockdown of USP10 attenuated the ability of RBE cells to form tumors subcutaneously in nude mice. Our results revealed that USP10 attenuates ICC cell malignancy by deubiquitinating SNAI1, indicating that USP10 could be developed as a therapeutic target for ICC treatment.

The AEG-1-USP10-PARP1 axis confers radioresistance in esophageal squamous cell carcinoma via facilitating homologous recombination-dependent DNA damage repair

Radiotherapy is the standard adjuvant treatment for esophageal squamous cell carcinoma (ESCC), yet radioresistance remains a major obstacle leading to treatment failure and unfavorable prognosis. Previous reports have demonstrated the involvement of astrocyte elevated gene-1 (AEG-1) in tumorigenesis and progression of multiple malignancies. Nevertheless, the precise role of AEG-1 in the radioresistance of ESCC remains elusive. Here, we unveiled a strong correlation between aberrant AEG-1 gene overexpression and malignant progression as well as adverse prognosis in ESCC patients. Moreover, both in vitro and in vivo investigations revealed that AEG-1 significantly alleviated irradiation-induced DNA damage and enhanced radiation resistance in ESCC cells. Mechanistically, AEG-1 recruited the deubiquitinase USP10 to remove the K48-linked polyubiquitin chains at the Lys425 of PARP1, thus preventing its proteasomal degradation. This orchestrated process facilitated homologous recombination-mediated DNA double-strand breaks (DSBs) repair, culminating in mitigated DNA damage and acquired radioresistance in ESCC cells. Notably, PARP1 overexpression reversed the radiosensitizing effect caused by AEG-1 deficiency. Collectively, these findings shed new light on the mechanism of ESCC radioresistance, providing potential therapeutic targets to enhance the efficacy of radiotherapy in ESCC.

Deubiquitinating PABPC1 by USP10 upregulates CLK2 translation to promote tumor progression in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is extremely malignant with limited treatment options. Deubiquitinases (DUBs), which cleave ubiquitin on substrates, can regulate tumor progression and are appealing therapeutic targets, but there are few related studies in PDAC. In our study, we screened the expression levels and prognostic value of USP family members based on published databases and selected USP10 as the potential interventional target in PDAC. IHC staining of the PDAC microarray revealed that USP10 expression was an adverse clinical feature of PDAC. USP10 promoted tumor growth both in vivo and in vitro in PDAC. Co-IP experiments revealed that USP10 directly interacts with PABPC1. Deubiquitination assays revealed that USP10 decreased the K27/29-linked ubiquitination level of the RRM2 domain of PABPC1. Deubiquitinated PABPC1 was able to couple more CLK2 mRNA and eIF4G1, which increased the translation efficiency. Replacing PABPC1 with a mutant that could not be ubiquitinated impaired USP10 knock-down-mediated tumor suppression in PDAC. Targeting USP10 significantly delayed the growth of cell-derived xenograft and patient-derived xenograft tumors. Collectively, our study first identified USP10 as the DUB of PABPC1 and provided a rationale for potential therapeutic options for PDAC with high USP10 expression.

USP33 promotes nonalcoholic fatty acid disease-associated fibrosis in gerbils via the c-myc signaling

Nonalcoholic fatty acid disease (NAFLD) is a common complication of obesity associated with liver fibrosis. The underlying molecular mechanisms involved in the progression from normal to fibrosis remain unclear. Liver tissues from the liver fibrosis model identified the USP33 gene as a key gene in NAFLD-associated fibrosis. USP33 knockdown inhibited hepatic stellate cell activation and glycolysis in gerbils with NAFLD-associated fibrosis. Conversely, overexpression of USP33 caused a contrast function on hepatic stellate cell activation and glycolysis activation, which was inhibited by c-Myc inhibitor 10058-F4. The copy number of short-chain fatty acids-producing bacterium Alistipes sp. AL-1, Mucispirillum schaedleri, Helicobacter hepaticus in the feces, and the total bile acid level in serum were higher in gerbils with NAFLD-associated fibrosis. Bile acid promoted USP33 expression and inhibiting its receptor reversed hepatic stellate cell activation in gerbils with NAFLD-associated fibrosis. These results suggest that the expression of USP33, an important deubiquitinating enzyme, is increased in NAFLD fibrosis. These data also point to hepatic stellate cells as a key cell type that may respond to liver fibrosis via USP33-induced cell activation and glycolysis.

USP10 Contributes to Colon Carcinogenesis via mTOR/S6K Mediated HIF-1α but Not HIF-2α Protein Synthesis

Colorectal cancer ranks among the third most common human malignant diseases and is one of the leading causes of cancer-related deaths globally. Colon cancer cells are hypoxic and display disturbed protein homeostasis. Ubiquitin-ligase-initiated proteasomal degradation as well as its prevention by deubiquitinases (DUBs) are supposed to contribute to the above-mentioned disturbances. However, not much is known about the involvement of ubiquitinating and deubiquitinating enzymes in colon cancer and their effect on the hypoxia response. Here, we identify the DUB ubiquitin-specific protease 10 (USP10) as an important player in the control of colon cancer progression and a new modifier of the hypoxia response. Mechanistically, we show that knockout of USP10 in different colon cancer cells causes an elevation in HIF-1α but not HIF-2α protein levels under both normoxic and hypoxic conditions. In addition, the lack of USP10 increased cellular migration, reduced cell adhesion, and switched the energy phenotype towards increased glycolysis and enhanced extracellular acidification. These changes were at least partially caused by HIF-1α, as the knockdown of HIF-1α rescued the cellular phenotype caused by USP10 deficiency. Interestingly, the USP10-dependent increase in HIF-1 α was neither caused by enhanced transcription nor prolonged half-life but via mTOR/S6K mediated HIF-1α protein synthesis. Together, the current findings indicate that USP10 is able to participate in colon carcinogenesis by modulating the hypoxia response and may therefore represent a new therapeutic target.

A review of deubiquitinases and thier roles in tumorigenesis and development

Ubiquitin is a small protein that can be added onto target protein for inducing target degradation, thereby modulating the activity and stability of protein. Relatively, deubiquitinases (DUBs), a class catalase that can remove ubiquitin from substrate protein, provide a positive regulation of the protein amount at transcription level, post-translational modification, protein interaction, etc. The reversible and dynamic ubiquitination-deubiquitination process plays an essential role in maintaining protein homeostasis, which is critical to almost all the biological processes. Therefore, the metabolic dysregulation of deubiquitinases often lead to serious consequences, including the growth and metastasis of tumors. Accordingly, deubiquitinases can be served as key drug targets for the treatment of tumors. The small molecule inhibitors targeting deubiquitinases has become one of the hot spots of anti-tumor drug research areas. This review concentrated on the function and mechanism of deubiquitinase system in the proliferation, apoptosis, metastasis and autophagy of tumor cells. The research status of small molecule inhibitors of specific deubiquitinases in tumor treatment is introduced, aiming to provide reference for the development of clinical targeted drugs.

The Ubiquitin-Proteasome System in Tumor Metabolism

Metabolic reprogramming, which is considered a hallmark of cancer, can maintain the homeostasis of the tumor environment and promote the proliferation, survival, and metastasis of cancer cells. For instance, increased glucose uptake and high glucose consumption, known as the "Warburg effect," play an essential part in tumor metabolic reprogramming. In addition, fatty acids are harnessed to satisfy the increased requirement for the phospholipid components of biological membranes and energy. Moreover, the anabolism/catabolism of amino acids, such as glutamine, cystine, and serine, provides nitrogen donors for biosynthesis processes, development of the tumor inflammatory environment, and signal transduction. The ubiquitin-proteasome system (UPS) has been widely reported to be involved in various cellular biological activities. A potential role of UPS in the metabolic regulation of tumor cells has also been reported, but the specific regulatory mechanism has not been elucidated. Here, we review the role of ubiquitination and deubiquitination modification on major metabolic enzymes and important signaling pathways in tumor metabolism to inspire new strategies for the clinical treatment of cancer.

Research Progress for Targeting Deubiquitinases in Gastric Cancers

Gastric cancers (GCs) are malignant tumors with a high incidence that threaten global public health. Despite advances in GC diagnosis and treatment, the prognosis remains poor. Therefore, the mechanisms underlying GC progression need to be identified to develop prognostic biomarkers and therapeutic targets. Ubiquitination, a post-translational modification that regulates the stability, activity, localization, and interactions of target proteins, can be reversed by deubiquitinases (DUBs), which can remove ubiquitin monomers or polymers from modified proteins. The dysfunction of DUBs has been closely linked to tumorigenesis in various cancer types, and targeting certain DUBs may provide a potential option for cancer therapy. Multiple DUBs have been demonstrated to function as oncogenes or tumor suppressors in GC. In this review, we summarize the DUBs involved in GC and their associated upstream regulation and downstream mechanisms and present the benefits of targeting DUBs for GC treatment, which could provide new insights for GC diagnosis and therapy.