USP26 promotes anaplastic thyroid cancer progression by stabilizing TAZ

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.

A ubiquitin-proteasome system-related signature to predict prognosis, immune infiltration, and therapy efficacy for breast cancer

The ubiquitin-proteasome system (UPS) is an essential regulatory system for maintaining homeostasis, and its dysfunction may cause various diseases. The activity of proteasome and ubiquitin-conjugating enzymes has been found to be greatly increased in breast cancer (BC), indicating that the heterogeneity of UPS may be related to the progression of BC. Gene data was obtained from The Cancer Genome Atlas and Gene Expression Omnibus databases and performed in multiple algorithms to construct a UPS-related signature for BC. Patients in the UPS low-risk group had greater overall and recurrence-free survival probability than those in the UPS high-risk group. This signature was closely associated with functional enrichment. Some high metabolism-related pathways were more active in the UPS high-risk group. The UPS low-risk group had more abundant anti-tumor immune cells, while in the UPS high-risk group, immunosuppressive cells were dominant. More importantly, we found that the UPS low-risk group was more sensitive to immunotherapy, while the UPS high-risk group responded better to radiotherapy. Drug sensitivity analysis identified more effective chemotherapy drugs in different UPS-related risk groups. This UPS-related signature may serve as a novel biomarker and independent prognostic factor for BC. It can effectively predict prognosis, immune infiltration, and therapy efficacy, providing new strategies for individualized treatment.

USP26 promotes colorectal cancer tumorigenesis by restraining PRKN-mediated mitophagy

Deubiquitinating enzymes (DUBs) are promising targets for cancer therapy because of their pivotal roles in various physiological and pathological processes. Among these, ubiquitin-specific peptidase 26 (USP26) is a protease with crucial regulatory functions. Our study sheds light on the upregulation of USP26 in colorectal cancer (CRC), in which its increased expression correlates with an unfavorable prognosis. Herein, we evidenced the role of USP26 in promoting CRC tumorigenesis in a parkin RBR E3 ubiquitin-protein ligase (PRKN) protein-dependent manner. Our investigation revealed that USP26 directly interacted with PRKN protein, facilitating its deubiquitination, and subsequently reducing its activity. Additionally, we identified the K129 site on PRKN as a specific target for USP26-mediated deubiquitination. Our research highlights that a K-to-R mutation at the site on PRKN diminishes its potential for activation and ability to mediate mitophagy. In summary, our findings underscore the significance of USP26-mediated deubiquitination in restraining the activation of the PRKN-mediated mitophagy pathway, ultimately driving CRC tumorigenesis. This study not only elucidated the multifaceted role of USP26 in CRC but also introduced a promising avenue for therapeutic exploration through the development of small molecule inhibitors targeting USP26. This strategy holds promise as a novel therapeutic approach for CRC.

Ubiquitin specific peptidase 38 epigenetically regulates KLF transcription factor 5 to augment malignant progression of lung adenocarcinoma

Protein ubiquitination is a common post-translational modification and a critical mechanism for regulating protein stability. This study aimed to explore the role and potential molecular mechanism of ubiquitin-specific peptidase 38 (USP38) in the progression of lung adenocarcinoma (LUAD). USP38 expression was significantly higher in patients with LUAD than in their counterparts, and higher USP38 expression was closely associated with a worse prognosis. USP38 silencing suppresses the proliferation of LUAD cells in vitro and impedes the tumorigenic activity of cells in xenograft mouse models in vivo. Further, we found that USP38 affected the protein stability of transcription factor Krüppel-like factors 5 (KLF5) by inhibiting its degradation. Subsequent mechanistic investigations showed that the N-terminal of USP38 (residues 1-400aa) interacted with residues 1-200aa of KLF5, thereby stabilizing the KLF5 protein by deubiquitination. Moreover, we found that PIAS1-mediated SUMOylation of USP38 was promoted, whereas SENP2-mediated de-SUMOylation of USP38 suppressed the deubiquitination effects of USP38 on KLF5. Additionally, our results demonstrated that KLF5 overexpression restored the suppression of the malignant properties of LUAD cells by USP38 knockdown. SUMOylation of USP38 enhances the deubiquitination and stability of KLF5, thereby augmenting the malignant progression of LUAD.

Investigating the clinical role and prognostic value of genes related to insulin-like growth factor signaling pathway in thyroid cancer

BACKGROUND

Thyroid cancer (THCA) is the most common endocrine malignancy having a female predominance. The insulin-like growth factor (IGF) pathway contributed to the unregulated cell proliferation in multiple malignancies. We aimed to explore the IGF-related signature for THCA prognosis.

METHOD

The TCGA-THCA dataset was collected from the Cancer Genome Atlas (TCGA) for screening of key prognostic genes. The limma R package was applied for differentially expressed genes (DEGs) and the clusterProfiler R package was used for the Gene Ontology (GO) and KEGG analysis of DEGs. Then, the un/multivariate and least absolute shrinkage and selection operator (Lasso) Cox regression analysis was used for the establishment of RiskScore model. Receiver Operating Characteristic (ROC) analysis was used to verify the model's predictive performance. CIBERSORT and MCP-counter algorithms were applied for immune infiltration analysis. Finally, we analyzed the mutation features and the correlation between the RiskScore and cancer hallmark pathway by using the GSEA.

RESULT

We obtained 5 key RiskScore model genes for patient's risk stratification from the 721 DEGs. ROC analysis indicated that our model is an ideal classifier, the high-risk patients are associated with the poor prognosis, immune infiltration, high tumor mutation burden (TMB), stronger cancer stemness and stronger correlation with the typical cancer-activation pathways. A nomogram combined with multiple clinical features was developed and exhibited excellent performance upon long-term survival quantitative prediction.

CONCLUSIONS

We constructed an excellent prognostic model RiskScore based on IGF-related signature and concluded that the IGF signal pathway may become a reliable prognostic phenotype in THCA intervention.

Investigating USP42 Mutation as Underlying Cause of Familial Non-Medullary Thyroid Carcinoma

In a family with Familial Non-Medullary Thyroid Carcinoma (FNMTC), our investigation using Whole-Exome Sequencing (WES) uncovered a novel germline USP42 mutation [p.(Gly486Arg)]. USP42 is known for regulating p53, cell cycle arrest, and apoptosis, and for being reported as overexpressed in breast and gastric cancer patients. Recently, a USP13 missense mutation was described in FNMTC, suggesting a potential involvement in thyroid cancer. Aiming to explore the USP42 mutation as an underlying cause of FNMTC, our team validated the mutation in blood and tissue samples from the family. Using immunohistochemistry, the expression of USP42, Caspase-3, and p53 was assessed. The USP42 gene was silenced in human thyroid Nthy-Ori 3-1 cells using siRNAs. Subsequently, expression, viability, and morphological assays were conducted. p53, Cyclin D1, p21, and p27 proteins were evaluated by Western blot. USP42 protein was confirmed in all family members and was found to be overexpressed in tumor samples, along with an increased expression of p53 and cleaved Caspase-3. siRNA-mediated USP42 downregulation in Nthy-Ori 3-1 cells resulted in reduced cell viability, morphological changes, and modifications in cell cycle-related proteins. Our results suggest a pivotal role of USP42 mutation in thyroid cell biology, and this finding indicates that USP42 may serve as a new putative target in FNMTC.

Synergistic effect of YOD1 and USP21 on the Hippo signaling pathway

BACKGROUND

Deubiquitinating enzymes (DUBs) comprise a family of proteases responsible for cleaving the peptide or isopeptide bond between ubiquitin and its substrate proteins. Ubiquitin is essential for regulating diverse cellular functions by attaching to target proteins. The Hippo signaling pathway plays a crucial role in controlling tissue size, cell proliferation, and apoptosis. In a previous study, we discovered that YOD1 regulates the Hippo signaling pathway by deubiquitinating the neural precursor cell expressed developmentally down-regulated protein 4 (NEDD4), an E3 ligase of large tumor suppressor kinase 1 (LATS1). Here, our aim was to investigate potential substrates of YOD1 implicated in the Hippo signaling pathway.

METHODS

We employed various bioinformatics tools (BioGRID, STRING, and Cytoscape) to identify novel potential substrates of YOD1. Furthermore, we used western blotting, co-immunoprecipitation (co-IP), glutathione S-transferase (GST) pull-down, immunocytochemistry (ICC) assays to investigate cellular interactions. To evaluate cell proliferation, we performed cell counting kit-8 (CCK-8), wound healing, colony forming, and flow cytometry assays using A549, HEK293T, and HeLa cells. Additionally, we assessed the expression levels of YAP and p-YAP in A549, HEK293T, and HeLa cells through western blotting.

RESULTS

Our investigations revealed that YOD1 interacts with ubiquitin-specific proteases 21 (USP21), a DUB involved in the Hippo signaling pathway, and deubiquitinates the microtubule-affinity regulating kinase (MARK). Intriguingly, YOD1 and USP21 mutually deubiquitinate each other; while YOD1 regulates the protein stability of USP21, USP21 does not exert a regulatory effect on YOD1. Moreover, we observed the synergistic effect of YOD1 and USP21 on cell proliferation through the modulation of the Hippo signaling pathway.

CONCLUSIONS

Our study revealed multiple cellular interactions between YOD1 and USP21. Moreover, our findings suggest that the combined activities of YOD1 and USP21 synergistically influence cell proliferation in A549 cells by regulating the Hippo signaling pathway.

USP32 deubiquitinase: cellular functions, regulatory mechanisms, and potential as a cancer therapy target

An essential protein regulatory system in cells is the ubiquitin-proteasome pathway. The substrate is modified by the ubiquitin ligase system (E1-E2-E3) in this pathway, which is a dynamic protein bidirectional modification regulation system. Deubiquitinating enzymes (DUBs) are tasked with specifically hydrolyzing ubiquitin molecules from ubiquitin-linked proteins or precursor proteins and inversely regulating protein degradation, which in turn affects protein function. The ubiquitin-specific peptidase 32 (USP32) protein level is associated with cell cycle progression, proliferation, migration, invasion, and other cellular biological processes. It is an important member of the ubiquitin-specific protease family. It is thought that USP32, a unique enzyme that controls the ubiquitin process, is closely linked to the onset and progression of many cancers, including small cell lung cancer, gastric cancer, breast cancer, epithelial ovarian cancer, glioblastoma, gastrointestinal stromal tumor, acute myeloid leukemia, and pancreatic adenocarcinoma. In this review, we focus on the multiple mechanisms of USP32 in various tumor types and show that USP32 controls the stability of many distinct proteins. Therefore, USP32 is a key and promising therapeutic target for tumor therapy, which could provide important new insights and avenues for antitumor drug development. The therapeutic importance of USP32 in cancer treatment remains to be further proven. In conclusion, there are many options for the future direction of USP32 research.

USP1 modulates hepatocellular carcinoma progression via the Hippo/TAZ axis

Hepatocellular carcinoma (HCC) is one of the most lethal malignancies worldwide. The Hippo signaling pathway has emerged as a significant suppressive pathway for hepatocellular carcinogenesis. The core components of the Hippo pathway constitute a kinase cascade, which inhibits the functional activation of YAP/TAZ. Interestingly, the overactivation of YAP/TAZ is commonly observed in hepatocellular carcinoma, although the inhibitory kinase cascade of the Hippo pathway is still functional. Recent studies have indicated that the ubiquitin‒proteasome system also plays important roles in modulating Hippo signaling activity. Our DUB (deubiquitinase) siRNA screen showed that USP1 is a critical regulator of Hippo signaling activity. Analysis of TCGA data demonstrated that USP1 expression is elevated in HCC and associated with poor survival in HCC patients. RNA sequencing analysis revealed that USP1 depletion affects Hippo signaling activity in HCC cell lines. Mechanistic assays revealed that USP1 is required for Hippo/TAZ axis activity and HCC progression. USP1 interacted with the WW domain of TAZ, which subsequently enhanced TAZ stability by suppressing K11-linked polyubiquitination of TAZ. Our study identifies a novel mechanism linking USP1 and TAZ in regulating the Hippo pathway and one possible therapeutic target for HCC.

Insights Into the Properties, Biological Functions, and Regulation of USP21

Deubiquitylating enzymes (DUBs) antagonize ubiquitination by removing ubiquitin from their substrates. The role of DUBs in controlling various physiological and pathological processes has been extensively studied, and some members of DUBs have been identified as potential therapeutic targets in diseases ranging from tumors to neurodegeneration. Ubiquitin-specific protease 21 (USP21) is a member of the ubiquitin-specific protease family, the largest subfamily of DUBs. Although USP21 was discovered late and early research progress was slow, numerous studies in the last decade have gradually revealed the importance of USP21 in a wide variety of biological processes. In particular, the pro-carcinogenic effect of USP21 has been well elucidated in the last 2 years. In the present review, we provide a comprehensive overview of the current knowledge on USP21, including its properties, biological functions, pathophysiological roles, and cellular regulation. Limited pharmacological interventions for USP21 have also been introduced, highlighting the importance of developing novel and specific inhibitors targeting USP21.