The deubiquitinating enzyme STAMBP is a newly discovered driver of triple-negative breast cancer progression that maintains RAI14 protein stability

USP46 promotes the interferon antiviral signaling in black carp by deubiquitinating TBK1

Ubiquitin-specific peptidase 46 (USP46) functions as a deubiquitinating enzyme, facilitating the removal of ubiquitin molecules attached to substrate proteins and playing a critical role in cancer and neurodegenerative diseases. However, its function in innate antiviral immunity is unknown. In this study we cloned and identified bcUSP46, a homolog of USP46 from black carp. We discovered that overexpression of bcUSP46 enhanced the transcription of interferon (IFN) promoters and increased the expression of IFN, PKR, and Mx1. In addition, bcUSP46 knockdown significantly inhibited the expression of ISG genes, as well as the antiviral activity of the host cells. Interestingly, when bcUSP46 was co-expressed with the RLR factors, it significantly enhanced the activity of the IFN promoter mediated by these factors, especially TANK-binding kinase 1 (TBK1). The subsequent co-immunoprecipitation (co-IP) and immunofluorescence (IF) assay confirmed the association between bcUSP46 and bcTBK1. Noteworthily, co-expression of bcUSP46 with bcTBK1 led to an elevation of bcTBK1 protein level. Further analysis revealed that bcUSP46 stabilized bcTBK1 by eliminating the K48-linked ubiquitination of bcTBK1. Overall, our findings highlight the unique role of USP46 in modulating TBK1/IFN signaling and enrich our knowledge of the function of deubiquitination in regulating innate immunity in vertebrates.

IGFBP6 regulates extracellular vesicles formation via cholesterol abundance in MDA-MB-231 cells

Breast cancer recurrence is associated with the growth of disseminated cancer cells that separate from the primary tumor before surgical treatment and hormonal therapy and form a metastatic niche in distant organs. We previously demonstrated that IGFBP6 expression is associated with the risk of early relapse of luminal breast cancer. Knockdown of IGFBP6 in MDA-MB-231 breast cancer cells increased their invasiveness, proliferation, and metastatic potential. In addition, the knockdown of IGFBP6 leads to impaired lipid metabolism. In this study, we demonstrated that the knockdown of the IGFBP6 gene, a highly selective inhibitor of IGF-II, led to a significant decline in the number of secreted extracellular vesicles (EVs) and altered cholesterol metabolism in MDA-MB-231 cells. Knockdown of IGFBP6 led to a decrease in the essential proteins responsible for the biogenesis of cholesterol LDLR and LSS, which reduced the amount by more than 13 times. In addition, the knockdown of IGFBP6 led to a possible change in the profile of adhesion molecules on the surface of EVs. The expression of L1CAM, IGSF3, EpCAM, CD24, and CD44 decreased, and the expression of EGFR increased. We can conclude that the negative prognostic value of low expression of this gene could be associated with increased activity of IGF2 in tumor-associated fibroblasts due to low secretion of IGFBP6 by tumor cells. In addition, changing the profile of adhesion molecules on the surface of tumor EVs may contribute to the more efficient formation of metastatic niches.

The deubiquitinase BRCC3 increases the stability of ZEB1 and promotes the proliferation and metastasis of triple-negative breast cancer cells

Triple negative breast cancer (TNBC) has a high recurrence rate, metastasis rate and mortality rate. The aim of this study is to identify new targets for the treatment of TNBC. Clinical samples are used for screening deubiquitinating enzymes (DUBs). MDA-MB-231 cells and a TNBC mouse model are used for in vitro and in vivo experiments, respectively. Western blot analysis is used to detect the protein expressions of DUBs, zinc finger E-box binding homeobox 1 (ZEB1), and epithelial-mesenchymal transition (EMT)-related markers. Colony formation and transwell assays are used to detect the proliferation, migration and invasion of TNBC cells. Wound healing assay is used to detect the mobility of TNBC cells. Immunoprecipitation assay is used to detect the interaction between breast cancer susceptibility gene 1/2-containing complex subunit 3 (BRCC3) and ZEB1. ZEB1 ubiquitination levels, protein stability, and protein degradation are also examined. Pathological changes in the lung tissues are detected via HE staining. Our results show a significant positive correlation between the expressions of BRCC3 and ZEB1 in clinical TNBC tissues. Interference with BRCC3 inhibits TNBC cell proliferation, migration, invasion and EMT. BRCC3 interacts with ZEB1 and interferes with BRCC3 to inhibit ZEB1 expression by increasing ZEB1 ubiquitination. Interference with BRCC3 inhibits TNBC cell tumorigenesis and lung metastasis in vivo. In all, this study demonstrates that BRCC3 can increase the stability of ZEB1, upregulate ZEB1 expression, and promote the proliferation, migration, invasion, EMT, and metastasis of TNBC cells, providing a new direction for cancer therapy.

Dysregulation of deubiquitination in breast cancer

Breast cancer (BC) is a highly frequent malignant tumor that poses a serious threat to women's health and has different molecular subtypes, histological subtypes, and biological features, which act by activating oncogenic factors and suppressing cancer inhibitors. The ubiquitin-proteasome system (UPS) is the main process contributing to protein degradation, and deubiquitinases (DUBs) are reverse enzymes that counteract this process. There is growing evidence that dysregulation of DUBs is involved in the occurrence of BC. Herein, we review recent research findings in BC-associated DUBs, describe their nature, classification, and functions, and discuss the potential mechanisms of DUB-related dysregulation in BC. Furthermore, we present the successful treatment of malignant cancer with DUB inhibitors, as well as analyzing the status of targeting aberrant DUBs in BC.

Serum protein profiling reveals an inflammation signature as a predictor of early breast cancer survival

BACKGROUND

Breast cancers exhibit considerable heterogeneity in their biology, immunology, and prognosis. Currently, no validated, serum protein-based tools are available to evaluate the prognosis of patients with early breast cancer.

METHODS

The study population consisted of 521 early-stage breast cancer patients with a median follow-up of 8.9 years. Additionally, 61 patients with breast fibroadenoma or atypical ductal hyperplasia were included as controls. We used a proximity extension assay to measure the preoperative serum levels of 92 proteins associated with inflammatory and immune response processes. The invasive cancers were randomly split into discovery (n = 413) and validation (n = 108) cohorts for the statistical analyses.

RESULTS

Using LASSO regression, we identified a nine-protein signature (CCL8, CCL23, CCL28, CSCL10, S100A12, IL10, IL10RB, STAMPB2, and TNFβ) that predicted various survival endpoints more accurately than traditional prognostic factors. In the time-dependent analyses, the prognostic power of the model remained rather stable over time. We also developed and validated a 17-protein model with the potential to differentiate benign breast lesions from malignant lesions (Wilcoxon p < 2.2*10- 16; AUC 0.94).

CONCLUSIONS

Inflammation and immunity-related serum proteins have the potential to rise above the classical prognostic factors of early-stage breast cancer. They may also help to distinguish benign from malignant breast lesions.

TET2 stabilized by deubiquitinase USP21 ameliorates cigarette smoke-induced apoptosis in airway epithelial cells

DNA demethylase TET2 was related with lung function. However, the precise role of TET2 in cigarette smoke (CS)-induced apoptosis of airway epithelium cells, and the mechanisms involved, have yet to be elucidated. Here, we showed that CS decreased TET2 protein levels but had no significant effect on its mRNA levels in lung tissues of chronic obstructive pulmonary disease (COPD) patients and CS-induced COPD mice model and even in airway epithelial cell lines. TET2 could inhibit CS-induced apoptosis of airway epithelial cell in vivo and in vitro. Moreover, we identified ubiquitin-specific protease 21 (USP21) as a deubiquitinase of TET2 in airway epithelial cells. USP21 interacted with TET2 and inhibited CSE-induced TET2 degradation. USP21 downregulated decreased TET2 abundance and further reduced the anti-apoptosis effect of TET2. Thus, we draw a conclusion that the USP21/TET2 axis is involved in CS-induced apoptosis of airway epithelial cells.

Spotlights on ubiquitin-specific protease 12 (USP12) in diseases: from multifaceted roles to pathophysiological mechanisms

Ubiquitination is one of the most significant post-translational modifications that regulate almost all physiological processes like cell proliferation, autophagy, apoptosis, and cell cycle progression. Contrary to ubiquitination, deubiquitination removes ubiquitin from targeted protein to maintain its stability and thus regulate cellular homeostasis. Ubiquitin-Specific Protease 12 (USP12) belongs to the biggest family of deubiquitinases named ubiquitin-specific proteases and has been reported to be correlated with various pathophysiological processes. In this review, we initially introduce the structure and biological functions of USP12 briefly and summarize multiple substrates of USP12 as well as the underlying mechanisms. Moreover, we discuss the influence of USP12 on tumorigenesis, tumor immune microenvironment (TME), disease, and related signaling pathways. This study also provides updated information on the roles and functions of USP12 in different types of cancers and other diseases, including prostate cancer, breast cancer, lung cancer, liver cancer, cardiac hypertrophy, multiple myeloma, and Huntington's disease. Generally, this review sums up the research advances of USP12 and discusses its potential clinical application value which deserves more exploration in the future.

The ubiquitin-proteasome system in breast cancer

Ubiquitin-proteasome system (UPS) is a selective proteolytic system that is associated with the expression or function of target proteins and participates in various physiological and pathological processes of breast cancer. Inhibitors targeting the 26S proteasome in combination with other drugs have shown promising therapeutic effects in the clinical treatment of breast cancer. Moreover, several inhibitors/stimulators targeting other UPS components are also effective in preclinical studies, but have not yet been applied in the clinical treatment of breast cancer. Therefore, it is vital to comprehensively understand the functions of ubiquitination in breast cancer and to identify potential tumor promoters or tumor suppressors among UPS family members, with the aim of developing more effective and specific inhibitors/stimulators targeting specific components of this system.

Analysis of Protein Degradation in Ferroptosis

The ubiquitin-proteasome system (UPS) is a highly conserved cellular mechanism that degrades and recycles proteins in eukaryotic cells. It involves the tagging of specific target proteins with ubiquitin, a small regulatory protein, which marks them for degradation by the proteasome, a large protein complex that acts as a molecular shredder. Dysfunction of the UPS has been implicated in a wide range of diseases, including cancer, neurodegenerative disorders, and viral infections. Therefore, targeting the UPS has become an attractive therapeutic strategy for many diseases. Ferroptosis is an iron-dependent cell death process that is regulated by multiple levels, including protein degradation. In this chapter, we introduce the detection of UPS-mediated protein degradation in ferroptosis using several techniques such as western blotting, co-immunoprecipitation, in vitro ubiquitination assay, and proteasome assay.