The deubiquitinating enzyme PSMD14 facilitates tumor growth and chemoresistance through stabilizing the ALK2 receptor in the initiation of BMP6 signaling pathway

Prognostic biomarker PSMD14 facilitates bladder cancer tumorigenesis and progression by regulating Nucleolin-YAP1 axis

Deubiquitinating enzymes (DUBs) significantly contribute to tumor progression and treatment resistance in bladder cancer. However, the mechanisms by which DUBs promote malignant behavior in patients with bladder cancer remain poorly understood. Using online databases such as TCGA, GSE13507, and GSE23894, along with clinical sample validation, the expression profiles of PSMD14 in patients with bladder cancer were identified. The analysis revealed correlations among PSMD14, nucleolin (NCL), and YAP1, which were verified using TCGA data and clinical sample studies. In this study, PSMD14 was identified as a novel DUB involved in bladder cancer malignancy. PSMD14 expression is upregulated in the tissues of patients with bladder cancer and is associated with poor clinical outcomes. Both in vitro and in vivo experiments demonstrated that PSMD14 inhibition significantly reduced bladder cancer cell proliferation, metastasis, and cisplatin resistance. Mechanistic investigations revealed that PSMD14 enhances protein stability and NCL expression through deubiquitination. NCL, an RNA-binding protein, exerts oncogenic effects in patients with bladder cancer by binding to and stabilizing YAP1 mRNA, leading to increased YAP1 expression and activation of downstream YAP1-related pathways. Notably, the tumor-suppressive effects of PSMD14 inhibition were partially reversed by the overexpression of either NCL or YAP1. In conclusion, the PSMD14/NCL/YAP1 axis plays a pivotal role in the malignant behavior of bladder cancer, including proliferation, metastasis, and chemoresistance. These findings suggest that PSMD14 is a critical biomarker for predicting bladder cancer prognosis and is a potential target for therapeutic interventions.

Blocking PSMD14-mediated E2F1/ERK/AKT signaling pathways suppresses the progression of anaplastic thyroid cancer

Anaplastic thyroid cancer (ATC) is the most aggressive subtype of thyroid cancer with few effective therapeutic strategies. Recent studies have identified the deubiquitinating enzyme (DUB) 26S proteasome non-ATPase regulatory subunit 14 (PSMD14) as a promising therapeutic target for multiple cancers; however, the role of PSMD14 in ATC remains largely unknown. Here, we found that PSMD14 was upregulated in ATC tissues and that its aberrant expression was negatively associated with the overall survival of patients with ATC. Functionally, PSMD14 promotes the proliferation and invasiveness of ATC cells, whereas the depletion of PSMD14 or PSMD14 inhibitor thiolutin (THL) inhibits the growth, invasiveness, and epithelial-mesenchymal transition ((EMT) of ATC cells. In addition, the cell cycle was arrested and apoptosis was increased in PSMD14-depleted ATC or ATC cells treated with THL in vitro. An in vivo assay indicated that THL exerted a potent inhibitory effect on ATC xenografts. Mechanistically, PSMD14 increased E2F1 stabilization by binding to and deubiquitinating E2F1. PSMD14-regulated E2F1 improved the activation of the ERK and AKT signaling pathways, which are instrumental in ATC tumorigenesis and progression. Overall, our findings reveal the oncogenic role of PSMD14 in ATC and provide a promising therapeutic target for the treatment of ATC.

Emerging role of deubiquitinases in modulating cancer chemoresistance

Chemotherapy remains a gold standard in cancer treatment by targeting the rapidly dividing cancer cells. However, chemoresistance is a major obstacle to successful cancer treatment, often leading to recurrence, metastasis, and high mortality. Deubiquitinases (DUBs), enzymes that remove ubiquitin and stabilize proteins, have been implicated in chemoresistance and can either promote therapeutic resistance or enhance sensitivity depending on their targets. In this review, we highlight the chemoresistance mechanisms of DUBs in various cancers, including breast, lung, liver, gastrointestinal, colorectal, ovarian, prostate, and blood cancers. Given these mechanisms, the development of DUB inhibitors has gained considerable attention in cancer therapeutics and combination therapies involving these inhibitors show potential to overcome drug resistance and improving treatment outcomes.

Histone lactylation stimulated upregulation of PSMD14 alleviates neuron PANoptosis through deubiquitinating PKM2 to activate PINK1-mediated mitophagy after traumatic brain injury

Alleviating the multiple types of programmed neuronal death caused by mechanical injury has been an impetus for designing neuro-therapeutical approaches after traumatic brain injury (TBI). The aim of this study was to elucidate the potential role of PSMD14 (proteasome 26S subunit, non-ATPase 14) in neuron death and the specific mechanism through which it improves prognosis of TBI patients. Here, we identified differential expression of the PSMD14 protein between the controlled cortical impact (CCI) and sham mouse groups by LC-MS proteomic analysis and found that PSMD14 was significantly upregulated in neurons after brain injury by qPCR and western blot. PSMD14 suppressed stretch-induced neuron PANoptosis and improved motor ability and learning performance after CCI in vivo. Mechanistically, PSMD14 improved PINK1 phosphorylation levels at Thr257 and activated PINK1-mediated mitophagy by deubiquitinating PKM/PKM2 (pyruvate kinase M1/2) to maintain PKM protein stability. PSMD14-induced mitophagy promoted mitochondrial homeostasis to reduced ROS production, and ultimately inhibited the neuron PANoptosis. The upregulation of neuronal PSMD14 after TBI was due to the increase of histone lactation modification level and lactate treatment alleviated neuron PANoptosis via increasing PSMD14 expression. Our findings suggest that PSMD14 could be a potential therapeutic approach for improving the prognosis of TBI patients.Abbreviations: CCI: controlled cortical impact; CQ: chloroquine; DUBs: deubiquitinating enzymes; H3K18la: H3 lysine 18 lactylation; IB: immunoblot; IHC: immunohistochemistry; IP: immunoprecipitation; MLKL: mixed lineage kinase domain like pseudokinase; PI3K: phosphoinositide 3-kinase; PINK1: PTEN induced kinase 1; PKM/PKM2: pyruvate kinase M1/2; PSMD14: proteasome 26S subunit, non-ATPase 14; ROS: reactive oxygen species; RIPK1: receptor interacting serine/threonine kinase 1; RIPK3: receptor interacting serine/threonine kinase 3; TBI: traumatic brain injury.

PSMD14-mediated deubiquitination of CARM1 facilitates the proliferation and metastasis of hepatocellular carcinoma by inducing the transcriptional activation of FERMT1

Hepatocellular carcinoma (HCC) is a highly potent malignancy. The enzyme coactivator-associated arginine methyltransferase 1 (CARM1) is highly expressed in different types of cancer. However, the precise levels of expression, clinical significance, biological functions, and molecular mechanisms of CARM1 in HCC, particularly related to the downstream genes regulated by CARM1 through histone arginine methylation, remain unclear. In this study, we presented findings from the TCGA database and clinical samples, which collectively demonstrated the overexpression of CARM1 in HCC. Additionally, we found that the upregulation of CARM1 was mediated by PSMD14-induced deubiquitination. CARM1 promoted the proliferation and metastasis of HCC cells in vitro and in vivo. Mechanistic investigations further revealed that FERMT1 is a downstream gene of CARM1, and CARM1 activates the transcription of FERMT1 through the dimethylation of arginine 17 on histone 3 (H3R17me2). Additionally, administering SGC2085, a CARM1 inhibitor, effectively suppressed the malignant behaviors of HCC cells. To summarize, our findings provided strong evidence that CARM1 can serve as a key oncoprotein; thus, it holds promise as a therapeutic target for HCC.

The clinicopathological and prognostic significance of PSMD14 in cancers based on bioinformatics and meta-analysis

Aim: To evaluate the clinic-pathological features and prognostic value regarding PSMD14 in cancers.Materials & methods: Literature was gathered from public databases until 22 June 2023 to analyze data on survival rates and clinicopathological characteristics associated with PSMD14. TCGA and GEO data were also utilized for validation.Results: Eight reports on seven types of tumors showed that high PSMD14 expression was linked to poorer overall survival and disease-free survival. PSMD14 expression also correlated with larger tumor size, differentiation and metastasis, as well as the effectiveness of various chemotherapy drugs.Conclusion: PSMD14 could serve as a potential biomarker of poor prognosis in cancers, including lung cancer, head and neck squamous cell carcinoma, ovarian cancer, breast cancer and hepatocellular carcinoma.

E3 ubiquitin ligases and deubiquitinases in colorectal cancer: Emerging molecular insights and therapeutic opportunities

Colorectal cancer (CRC) presents ongoing challenges due to limited treatment effectiveness and a discouraging prognosis, underscoring the need for ground-breaking therapeutic approaches. This review delves into the pivotal role of E3 ubiquitin ligases and deubiquitinases (DUBs), underscoring their role as crucial regulators for tumor suppression and oncogenesis in CRC. We spotlight the diverse impact of E3 ligases and DUBs on CRC's biological processes and their remarkable versatility. We closely examine their specific influence on vital signaling pathways, particularly Wnt/β-catenin and NF-κB. Understanding these regulatory mechanisms is crucial for unravelling the complexities of CRC progression. Importantly, we explore the untapped potential of E3 ligases and DUBs as novel CRC treatment targets, discussing aspects that may guide more effective therapeutic strategies. In conclusion, our concise review illuminates the E3 ubiquitin ligases and deubiquitinases pivotal role in CRC, offering insights to inspire innovative approaches for transforming the treatment landscape in CRC.

Deubiquitinases as novel therapeutic targets for diseases

Deubiquitinating enzymes (DUBs) regulate substrate ubiquitination by removing ubiquitin or cleaving within ubiquitin chains, thereby maintaining cellular homeostasis. Approximately 100 DUBs in humans counteract E3 ubiquitin ligases, finely balancing ubiquitination and deubiquitination processes to maintain cellular proteostasis and respond to various stimuli and stresses. Given their role in modulating ubiquitination levels of various substrates, DUBs are increasingly linked to human health and disease. Here, we review the DUB family, highlighting their distinctive structural characteristics and chain-type specificities. We show that DUB family members regulate key signaling pathways, such as NF-κB, PI3K/Akt/mTOR, and MAPK, and play crucial roles in tumorigenesis and other diseases (neurodegenerative disorders, cardiovascular diseases, inflammatory disorders, and developmental diseases), making them promising therapeutic targets Our review also discusses the challenges in developing DUB inhibitors and underscores the critical role of the DUBs in cellular signaling and cancer. This comprehensive analysis enhances our understanding of the complex biological functions of the DUBs and underscores their therapeutic potential.

Deubiquitinase PSMD14 promotes tumorigenicity of glioblastoma by deubiquitinating and stabilizing β-catenin

The deubiquitinating enzyme 26S proteasome non-ATPase regulatory subunit 14 (PSMD14), a member of the JAB1/MPN/Mov34 metalloenzyme (JAMM) family, has been shown to function as an oncogene in various human cancers. However, the function of PSMD14 in glioma and the underlying mechanism remain unclear. In this study, our findings reveal a dramatic upregulation of PSMD14 in GBMs, which is associated with poor survival outcomes. Knocking down PSMD14 is associated with decreased proliferation and invasion of GBM cells in vitro and inhibited tumor growth in a xenograft mouse model. Mechanistically, PSMD14 directly interacts with β-catenin, leading to a decrease in the K48-linked ubiquitination of β-catenin and subsequent β-catenin stabilization. Increased β-catenin expression significantly reverses the inhibitory effects of PSMD14 knockdown on the migration, invasion, and tumor growth of GBM cells. Moreover, we observed a significant correlation between PSMD14 and β-catenin expression in human GBM samples. In summary, our results reveal that PSMD14 is a crucial deubiquitinase that is responsible for stabilizing the β-catenin protein, highlighting its potential for use as a therapeutic target for GBM.

BRCC3 Regulation of ALK2 in Vascular Smooth Muscle Cells: Implication in Pulmonary Hypertension

BACKGROUND

An imbalance of antiproliferative BMP (bone morphogenetic protein) signaling and proliferative TGF-β (transforming growth factor-β) signaling is implicated in the development of pulmonary arterial hypertension (PAH). The posttranslational modification (eg, phosphorylation and ubiquitination) of TGF-β family receptors, including BMPR2 (bone morphogenetic protein type 2 receptor)/ALK2 (activin receptor-like kinase-2) and TGF-βR2/R1, and receptor-regulated Smads significantly affects their activity and thus regulates the target cell fate. BRCC3 modifies the activity and stability of its substrate proteins through K63-dependent deubiquitination. By modulating the posttranslational modifications of the BMP/TGF-β-PPARγ pathway, BRCC3 may play a role in pulmonary vascular remodeling, hence the pathogenesis of PAH.

METHODS

Bioinformatic analyses were used to explore the mechanism by which BRCC3 deubiquitinates ALK2. Cultured pulmonary artery smooth muscle cells (PASMCs), mouse models, and specimens from patients with idiopathic PAH were used to investigate the rebalance between BMP and TGF-β signaling in regulating ALK2 phosphorylation and ubiquitination in the context of pulmonary hypertension.

RESULTS

BRCC3 was significantly downregulated in PASMCs from patients with PAH and animals with experimental pulmonary hypertension. BRCC3, by de-ubiquitinating ALK2 at Lys-472 and Lys-475, activated receptor-regulated Smad1/5/9, which resulted in transcriptional activation of BMP-regulated PPARγ, p53, and Id1. Overexpression of BRCC3 also attenuated TGF-β signaling by downregulating TGF-β expression and inhibiting phosphorylation of Smad3. Experiments in vitro indicated that overexpression of BRCC3 or the de-ubiquitin-mimetic ALK2-K472/475R attenuated PASMC proliferation and migration and enhanced PASMC apoptosis. In SM22α-BRCC3-Tg mice, pulmonary hypertension was ameliorated because of activation of the ALK2-Smad1/5-PPARγ axis in PASMCs. In contrast, Brcc3-/- mice showed increased susceptibility of experimental pulmonary hypertension because of inhibition of the ALK2-Smad1/5 signaling.

CONCLUSIONS

These results suggest a pivotal role of BRCC3 in sustaining pulmonary vascular homeostasis by maintaining the integrity of the BMP signaling (ie, the ALK2-Smad1/5-PPARγ axis) while suppressing TGF-β signaling in PASMCs. Such rebalance of BMP/TGF-β pathways is translationally important for PAH alleviation.

PSMD14 is a novel prognostic marker and therapeutic target in osteosarcoma

BACKGROUND

Osteosarcoma is a bone tumor that is characterized by high malignancy and a high mortality rate, and that originates from primitive osteoblastic mesenchymal cells and is most common in rapidly growing long bones. PSMD14, also known as RPN11 or POH1, is a member of the JAMM isopeptidase family, which is able to remove the substrate protein ubiquitination label, thereby regulating the stability and function of the substrate protein. In this study, we explored the expression and potential biological significance of the PSMD14 deubiquitinating enzyme in osteosarcoma.

METHODS

Immunohistochemical methods were used to detect the expression of PSMD14 in biopsies of 91 osteosarcoma patients, and the specimens were classified into high and low PSMD14 expression groups. The correlation between PSMD14 expression and clinical indicators and prognosis was compared.SiRNA was used to downregulate PSMD14 in two osteosarcoma cell lines (HOS and SJSA-1), and the effects of downregulation of PSMD14 on the viability, proliferation, and invasion ability of osteosarcoma cells were analyzed.

RESULTS

We identified significant differences in recurrence, metastasis, and survival time of the osteosarcoma patients on the basis of PSMD14 expression. High expression of PSMD14 in osteosarcoma patients was associated with a low survival rate and high risk of metastasis and recurrence. Down-regulation of PSMD14 inhibited the viability, proliferation, and invasiveness of osteosarcoma cell lines.

CONCLUSIONS

PSMD14 may be a new prognostic marker and therapeutic target for osteosarcoma.

Activin receptors in human cancer: Functions, mechanisms, and potential clinical applications

Activins are members of the transforming growth factor-β (TGF-β) superfamily and act as key regulators in various physiological processes, such as follicle and embryonic development, as well as in multiple human diseases, including cancer. They have been established to signal through three type I and two type II serine/threonine kinase receptors, which, upon ligand binding, form a final signal-transducing receptor complex that activates downstream signaling and governs gene expression. Recent research highlighted the dysregulation of the expression or activity of activin receptors in multiple human cancers and their critical involvement in cancer progression. Furthermore, expression levels of activin receptors have been associated with clinicopathological features and patient outcomes across different cancers. However, there is currently a paucity of comprehensive systematic reviews of activin receptors in cancer. Thus, this review aimed to consolidate existing knowledge concerning activin receptors, with a primary emphasis on their signaling cascade and emerging biological functions, regulatory mechanisms, and potential clinical applications in human cancers in order to provide novel perspectives on cancer prognosis and targeted therapy.

POH1 induces Smad3 deubiquitination and promotes lung cancer metastasis

Smad3 is the key mediator of TGF-β1-triggered signal transduction and the related biological responses, promoting cell invasion and metastasis in various cancers, including lung cancer. However, the deubiquitinase stabilizing Smad3 remains unknown. In this study, we present a paradigm in which POH1 is identified as a novel deubiquitinase of Smad3 that plays a tumor-promoting role in lung adenocarcinoma (LUAD) by regulating Smad3 stability. POH1 markedly increased Smad3 protein levels and prolonged its half-life. POH1 directly interacted and colocalized with Smad3, leading to the removal of poly-deubiquitination of Smad3. Functionally, POH1 facilitated cell proliferation, migration, and invasion by stabilizing Smad3. Importantly, POH1 also promoted liver metastasis of lung cancer cells. The protein levels of both POH1 and Smad3 were raised in the tumor tissues of patients with LUAD, which predicts poor prognosis. Collectively, we demonstrate that POH1 acts as an oncoprotein by enhancing TGF-β1/Smad3 signaling and TGF-β1-mediated metastasis of lung cancer.

Regulation of Drp1 and enhancement of mitochondrial fission by the deubiquitinating enzyme PSMD14 facilitates the proliferation of bladder cancer cells

The protein Dynein‑related protein 1 (Drp1) plays a crucial role in regulating the process of mitochondrial fission, which is known to be associated with the onset and progression of various human diseases. However, the specific impact of Drp1 on bladder cancer has yet to be fully understood. In previous studies, evidence to support the theory that the deubiquitinating enzyme proteasome non‑ATPase regulatory subunit 14 (PSMD14) is responsible for stabilizing and promoting the activity of Drp1, ultimately resulting in increased mitochondrial fission, has been presented. The levels of PSMD14 in both bladder cancer tissues and cells were elevated, as confirmed through immunohistochemical and immunofluorescent staining. Co‑immunoprecipitation and reciprocal co‑IP tests demonstrated that PSMD14 and Drp1 interacted with each other. Upon knockdown of PSMD14, there was a corresponding decrease in Drp1 expression and subsequent inhibition of mitochondrial fission. However, when the Drp1 agonist Mdivi‑1 was applied to cells where PSMD14 expression had been knocked down, a significant increase in cell growth was observed, partially restoring the cancer‑promoting effects of PSMD14 on cell proliferation. In conclusion, these findings suggest that PSMD14 may stimulate bladder cancer cell proliferation by promoting mitochondrial fission through the stabilization of Drp1.

Aberrant Expressions of PSMD14 in Tumor Tissue are the Potential Prognostic Biomarkers for Hepatocellular Carcinoma after Curative Resection

Introduction

Hepatocellular carcinoma (HCC) has a high mortality rate, with curative resection being the primary treatment. However, HCC patients have a large possibility of recurrence within 5 years after curative resection.

Methods

Thus, identifying biomarkers to predict recurrence is crucial. In our study, we analyzed data from CCLE, GEO, and TCGA, identifying eight oncogenes associated with HCC. Subsequently, the expression of 8 genes was tested in 5 cases of tumor tissues and the adjacent non-tumor tissues. Then ATP6AP1, PSMD14 and HSP90AB1 were selected to verify the expression in 63 cases of tumor tissues and the adjacent non-tumor tissues. The results showed that ATP6AP1, PSMD14, HSP90AB1 were generally highly expressed in tumor tissues. A five-year follow-up of the 63 clinical cases, combined with Kaplan-Meier Plotter's relapse-free survival (RFS) analysis, found a significant correlation between PSMD14 expression and recurrence in HCC patients. Subsequently, we analyzed the PSMD14 mutations and found that the PSMD14 gene mutations can lead to a shorter disease-free survival time for HCC patients.

Results

The results of enrichment analysis indicated that the differentially expressed genes related to PSMD14 are mainly enriched in the signal release pathway.

Conclusion

In conclusion, our research showed that PSMD14 might be related to recurrence in HCC patients, and the expression of PSMD14 in tumor tissue might be a potential prognostic biomarker after tumor resection in HCC patients.

The function and mechanism of PSMD14 in promoting progression and resistance to anlotinib in osteosarcoma

BACKGROUND

Osteosarcoma is a rare bone malignancy that frequently affects adolescents and poses formidable obstacles in its advanced stages. Studies revealed that PSMD14 may be a viable osteosarcoma treatment target. However, PSMD14's function and mechanism in osteosarcoma remain unknown. This study aimed to examine the function and mechanism of PSMD14 in the biological behavior of osteosarcoma and its role in anlotinib resistance.

METHODS

Western blotting, qRT-PCR, and immunohistochemistry (IHC) studies were used to examine PSMD14 levels. The role of PSMD14 in the malignant phenotype of osteosarcoma and its molecular pathway was explored by a series of studies, including Western blotting, cell amplification assay, transwell assay, and tumor growth. Furthermore, a series of in vitro investigations were done to determine the effect of PSMD14 on anlotinib-resistant osteosarcoma cell lines.

RESULTS

PSMD14 expression was elevated in osteosarcoma tissues compared to normal tissues. Overexpression of PSMD14 was associated with osteosarcoma patients' pathological grade and clinical stage, and PSMD14 was an independent poor prognostic factor. PSMD14 knockdown inhibits in vitro cell proliferation, migration, invasion, and in vivo tumor growth. PSMD14 knockdown has the potential to downregulate the PI3K/Akt/mTOR pathway, which was regarded as one of the key mechanisms promoting tumor growth. PSMD14 was likewise overexpressed in anlotinib-resistant OS cell lines, and its knockdown not only reduced the proliferation, migration, and invasion of subline cells and triggered cell apoptosis. Importantly, combination therapy with anlotinib enhanced these effects.

CONCLUSIONS

PSMD14 is substantially expressed in osteosarcoma and may be an independent risk factor associated with poor prognosis. It can promote tumor progression and anlotinib resistance in osteosarcoma and may promote osteosarcoma progression by modulating PI3K/AKT/mTOR signaling pathway.

PSMD8 can serve as potential biomarker and therapeutic target of the PSMD family in ovarian cancer: based on bioinformatics analysis and in vitro validation

BACKGROUND

The ubiquity-proteasome system is an indispensable mechanism for regulating intracellular protein degradation, thereby affecting human antigen processing, signal transduction, and cell cycle regulation. We used bioinformatics database to predict the expression and related roles of all members of the PSMD family in ovarian cancer. Our findings may provide a theoretical basis for early diagnosis, prognostic assessment, and targeted therapy of ovarian cancer.

METHODS

GEPIA, cBioPortal, and Kaplan-Meier Plotter databases were used to analyze the mRNA expression levels, gene variation, and prognostic value of PSMD family members in ovarian cancer. PSMD8 was identified as the member with the best prognostic value. The TISIDB database was used to analyze the correlation between PSMD8 and immunity, and the role of PSMD8 in ovarian cancer tissue was verified by immunohistochemical experiments. The relationship of PSMD8 expression with clinicopathological parameters and survival outcomes of ovarian cancer patients was analyzed. The effects of PSMD8 on malignant biological behaviors of invasion, migration, and proliferation of ovarian cancer cells were studied by in vitro experiments.

RESULTS

The expression levels of PSMD8/14 mRNA in ovarian cancer tissues were significantly higher than those in normal ovarian tissues, and the expression levels of PSMD2/3/4/5/8/11/12/14 mRNA were associated with prognosis. Up-regulation of PSMD4/8/14 mRNA expression was associated with poor OS, and the up-regulation of PSMD2/3/5/8 mRNA expression was associated with poor PFS in patients with ovarian serous carcinomas. Gene function and enrichment analysis showed that PSMD8 is mainly involved in biological processes such as energy metabolism, DNA replication, and protein synthesis. Immunohistochemical experiments showed that PSMD8 was mainly expressed in the cytoplasm and the expression level was correlated with FIGO stage. Patients with high PSMD8 expression had poor prognosis. Overexpression of PSMD8 significantly enhanced the proliferation, migration, and invasion abilities in ovarian cancer cells.

CONCLUSION

We observed different degrees of abnormal expression of members of PSMD family in ovarian cancer. Among these, PSMD8 was significantly overexpressed in ovarian malignant tissue, and was associated with poor prognosis. PSMDs, especially PSMD8, can serve as potential diagnostic and prognostic biomarkers and therapeutic targets in ovarian cancer.

Six immune-related promising biomarkers may promote hepatocellular carcinoma prognosis: a bioinformatics analysis and experimental validation

BACKGROUND

Abnormal miRNA and mRNA expression and dysregulated immune microenvironment have been found to frequently induce the progression of hepatocellular carcinoma (HCC) in recent reports. In particular, the immune-related competing endogenous RNAs (ceRNA) mechanism plays a crucial role in HCC progression. However, the underlying mechanisms remain unclear.

METHODS

Differentially expressed immune-related genes were obtained from the Immport, GEO, and TCGA databases. The mRNA and protein expression levels in HCC tissues and adjacent normal tissues were confirmed, and we further investigated the methylation levels of these biomarkers to explore their function. Then, the TIMER and TISCH databases were used to assess the relationship between immune infiltration and hub genes. Survival analysis and univariate and multivariate Cox models were used to evaluate the association between hub genes and HCC diagnosis. Hub gene expression was experimentally validated in six HCC cell lines and 15 HCC samples using qRT-PCR and immunohistochemistry. The hub genes were uploaded to DSigDB for drug prediction enrichment analysis.

RESULTS

We identified that patients with abnormal miRNAs (hsa-miR-125b-5p and hsa-miR-21-5p) and their targeted genes (NTF3, PSMD14, CD320, and SORT1) had a worse prognosis. Methylation analysis of miRNA-targeted genes suggested that alteration of methylation levels is also a factor in the induction of tumorigenesis. We also found that the development of HCC progression caused by miRNA-mRNA interactions may be closely correlated with the infiltration of immunocytes. Moreover, the GSEA, GO, and KEGG analysis suggested that several common immune-related biological processes and pathways were related to miRNA-targeted genes. The results of qRT-PCR, immunohistochemistry, and western blotting were consistent with our bioinformatics results, suggesting that abnormal miRNAs and their targeted genes may affect HCC progression.

CONCLUSIONS

Briefly, our study systematically describes the mechanisms of miRNA-mRNA interactions in HCC and predicts promising biomarkers that are associated with immune filtration for HCC progression.

Depletion of PSMD14 suppresses bladder cancer proliferation by regulating GPX4

Objective

The aim of this study was to investigate the role of deubiquitinase (DUB) 26S proteasome non-ATPase regulatory subunit 14 (PSMD14) in patients with bladder cancer.

Methods

From 2016 to 2018, 181 patients diagnosed with primary bladder cancer at the Affiliated Hospital of Qingdao University were recruited. The expression of PSMD14 in bladder cancer tissues was tested by immunochemistry. The association between PSMD14 expression and clinical and pathological data and outcomes of bladder cancer patients was determined. Overexpression and knockdown cells were constructed to evaluate the effects of PSMD14 on proliferation of bladder cancer cells.

Results

Our results showed that PSMD14 was significantly overexpressed in bladder cancer tissues compared to adjacent non-tumor tissues (76.24% vs 23.76%, P = 0.02). The expression of PSMD14 was significantly higher in patients with larger tumor diameters (85.14% vs 70.09%, P = 0.019) and patients with a family history of cancer (92.16% vs 70.00%, P = 0.002). Patients with high expression of PSMD14 had poor disease-free survival (DFS) (HR = 2.89, 95% CI [1.247-6.711], P = 0.013). Gain and loss of function experiments demonstrated that PSMD14 deficiency inhibited bladder cancer cell proliferation. Additionally, depletion of PSMD14 suppressed bladder cancer cell growth via down-regulation of GPX4, and the promotion of PSMD14-induced cell growth was observably reversed by the GPX4 inhibitor RSL3.

Conclusion

We determined that PSMD14 is highly expressed in bladder cancer tissues, and that PSMD14 expression correlated with poor disease-free survival. Depletion of PSMD14 could inhibit the proliferation of bladder cancer cells through the downregulation of GPX4. Therefore, PSMD14 may be an effective target for the treatment of bladder cancer.

Novel insights into the non-canonical roles of PSMD14/POH1/Rpn11 in proteostasis and in the modulation of cancer progression

PSMD14/POH1/Rpn11 plays a crucial role in cellular homeostasis. PSMD14 is a structural subunit of the lid subcomplex of the proteasome 19S regulatory particle with constitutive deubiquitinase activity. Canonically, PSMD14 removes the full ubiquitin chains with K48-linkages by hydrolyzing the isopeptide bond between the substrate and the C-terminus of the first ubiquitin, a crucial step for the entry of substrates into the catalytic barrel of the 20S proteasome and their subsequent degradation, all in context of the 26S proteasome. However, more recent discoveries indicate PSMD14 DUB activity is not only coupled to the translocation of substrates into the core of 20S proteasome. During the assembly of the lid, activity of PSMD14 has been detected in the context of the heterodimer with PSMD7. Additionally, assembly of the lid subcomplex occurs as an independent event of the base subcomplex and 20S proteasome. This feature opens the possibility that the regulatory particle, free lid subcomplex or the heterodimer PSMD14-PSMD7 might play other physiological roles including a positive function on protein stability through deubiquitination. Here we discuss scenarios that could enhance this PSMD14 non-canonical pathway, the potential impact in preventing degradation of substrates by autophagy highlighting the main findings that support this hypothesis. Finally, we discuss why this information should be investigated in biomedicine specifically with focus on cancer progression to design new therapeutic strategies against the lid subcomplex and the heterodimer PSMD14-PSMD7, highlighting PSMD14 as a druggable target for cancer therapy.

Inhibition of proteasomal deubiquitinases USP14 and UCHL5 overcomes tyrosine kinase inhibitor resistance in chronic myeloid leukaemia

Background

Chronic myeloid leukaemia (CML) is a haematological cancer featured by the presence of BCR‐ABL fusion protein with abnormal tyrosine kinase activation. Classical tyrosine kinase inhibitor (TKI)‐based therapies are available to patients with CML. However, acquired resistance to TKI has been a challenging obstacle, especially stubborn T315I mutation is the most common cause. Therefore, it is especially urgent to find more effective targets to overcome TKI resistance induced by BCR‐ABL^T315I. Proteasomal deubiquitinases (USP14 and UCHL5) have fundamental roles in the ubiquitin‐proteasome system and possess multiple functions during cancer progression.

Methods

The human peripheral blood mononuclear cells were collected to measure the mRNA expression of USP14 and UCHL5, as well as to detect the toxicity effect of b‐AP15. We explored the effect of b‐AP15 on the activity of proteasomal deubiquitinases. We detected the effects of b‐AP15 on BCR‐ABL^WT and BCR‐ABL^T315I CML cells in vitro and in the subcutaneous tumour model. We knocked down USP14 and/or UCHL5 by shRNA to explore whether these proteasomal deubiquitinases are required for cell proliferation of CML.

Results

In this study, we found that increased expression of the proteasomal deubiquitinase USP14 and UCHL5 in primary cancer cells from CML patients compared to healthy donors. b‐AP15, an inhibitor of USP14 and UCHL5, exhibited potent tumour‐killing activity in BCR‐ABL^WT and BCR‐ABL^T315I CML cell lines, as well as in CML xenografts and primary CML cells. Mechanically, pharmacological or genetic inhibition of USP14 and UCHL5 induced cell apoptosis and decreased the protein level of BCR‐ABL in CML cells expressing BCR‐ABL^WT and BCR‐ABL^T315I. Moreover, b‐AP15 synergistically enhanced the cytotoxic effect caused by TKI imatinib in BCR‐ABL^WT and BCR‐ABL^T315I CML cells.

Conclusion

Collectively, our results demonstrate targeting USP14 and UCHL5 as a potential strategy for combating TKI resistance in CML.

Deubiquitinases in Cancers: Aspects of Proliferation, Metastasis, and Apoptosis

Simple Summary

This review summarizes the current DUBs findings that correlate with the most common cancers in the world (liver, breast, prostate, colorectal, pancreatic, and lung cancers). The DUBs were further classified by their biological functions in terms of proliferation, metastasis, and apoptosis. The work provides an updated of the current findings, and could be used as a quick guide for researchers to identify target DUBs in cancers.

Abstract

Deubiquitinases (DUBs) deconjugate ubiquitin (UBQ) from ubiquitylated substrates to regulate its activity and stability. They are involved in several cellular functions. In addition to the general biological regulation of normal cells, studies have demonstrated their critical roles in various cancers. In this review, we evaluated and grouped the biological roles of DUBs, including proliferation, metastasis, and apoptosis, in the most common cancers in the world (liver, breast, prostate, colorectal, pancreatic, and lung cancers). The current findings in these cancers are summarized, and the relevant mechanisms and relationship between DUBs and cancers are discussed. In addition to highlighting the importance of DUBs in cancer biology, this study also provides updated information on the roles of DUBs in different types of cancers.

Deubiquitinase JOSD1 promotes tumor progression via stabilizing Snail in lung adenocarcinoma

Accumulating evidence suggests that the deubiquitinase JOSD1 accounts for aggressiveness and unfavorable prognosis in multiple human cancers. But, the significance of JOSD1 in lung adenocarcinoma (LUAD) is elusive. We established that JOSD1 was aberrantly overexpressed in LUAD tissues, relative to normal tissues. Elevated JOSD1 levels in LUAD tissues positively related to advanced clinicopathological characteristics and poor overall survival (OS) in LUAD patients. Furthermore, we found that JOSD1 knockdown suppressed tumor cell proliferation and metastasis, whereas overexpression of JOSD1 led to opposite phenotypes. Mechanistically, JOSD1 stabilized Snail protein through deubiquitination, which promotes the epithelial-to-mesenchymal transition (EMT) process. Indeed, JOSD1 promoted tumor cell invasion as well as metastasis on the dependence of Snail. The protein expression analysis of LUAD tissues indicated that JOSD1 positively correlated with Snail. Moreover, JOSD1 and Snail co-overexpression had the worst prognosis in LUAD patients. Overall, these results demonstrated that JOSD1 was significantly overexpressed in LUAD and stabilized Snail via deubiquitination to promote LUAD metastasis.

POH1/Rpn11/PSMD14: a journey from basic research in fission yeast to a prognostic marker and a druggable target in cancer cells

POH1/Rpn11/PSMD14 is a highly conserved protein in eukaryotes from unicellular organisms to human and has a crucial role in cellular homoeostasis. It is a subunit of the regulatory particle of the proteasome, where it acts as an intrinsic deubiquitinase removing polyubiquitin chains from substrate proteins. This function is not only coupled to the translocation of substrates into the core of the proteasome and their subsequent degradation but also, in some instances, to the stabilisation of ubiquitinated proteins through their deubiquitination. POH1 was initially discovered as a functional homologue of the fission yeast gene pad1⁺, which confers drug resistance when overexpressed. In translational studies, expression of POH1 has been found to be increased in several tumour types relative to normal adjacent tissue and to correlate with tumour progression, higher tumour grade, decreased sensitivity to cytotoxic drugs and poor prognosis. Proteasome inhibitors targeting the core particle of the proteasome are highly active in the treatment of myeloma, and recently developed POH1 inhibitors, such as capzimin and thiolutin, have shown promising anticancer activity in cell lines of solid tumours and leukaemia. Here we give an overview of POH1 function in the cell, of its potential role in oncogenesis and of recent progress in developing POH1-targeting drugs.

Construction and Validation of a Necroptosis-Related Signature Associated With the Immune Microenvironment in Liver Hepatocellular Carcinoma

Background: Liver hepatocellular carcinoma (LIHC) is a widespread and often deadly neoplasm. There is increasing evidence that necroptosis mediates numerous tumor-associated behaviors, as well as the regulation of the tumor microenvironment, suggesting its use as a biomarker for tumor prognosis.

Methods: Data on mRNA expression and necroptosis regulators were acquired from the TCGA and KEGG databases, respectively. Clinical liver hepatocellular carcinoma (LIHC) patient data and information on the expression of necroptosis regulators were processed by unsupervised cluster analysis was performed on LIHC patients together with necroptotic regulator expression and, differentially expressed necroptosis-related genes (DENRGs) were identified by comparing the two clusters. A signature based on eight DENRGs was constructed and verified through independent data sets, and its relationship with the tumor microenvironment was investigated.

Results: Unsupervised cluster analysis demonstrated inherent immune differences among LIHC patients. In all, 1,516 DENRGs were obtained by comparison between the two clusters. In the training set, the final eight genes obtained by univariate, LASSO, and multivariate Cox regression were utilized for constructing the signature. The survival and receiver operating characteristic (ROC) curve achieved satisfactory results in both sets. The high-risk group was characterized by greater immune infiltration and poor prognosis. The results of survival analysis based on the expression of eight DENRGs further confirmed the signature.

Conclusion: We established and validated a risk signature based on eight DERNGs related to the tumor microenvironment. This provides a possible explanation for the different clinical effects of immunotherapy and provides a novel perspective for predicting tumor prognosis in LIHC.

Integrated genomic analysis of proteasome alterations across 11,057 patients with 33 cancer types: clinically relevant outcomes in framework of 3P medicine

Relevance

Proteasome, a cylindrical complex containing 19S regulatory particle lid, 19S regulatory particle base, and 20S core particle, acted as a major mechanism to regulate the levels of intracellular proteins and degrade misfolded proteins, which involved in many cellular processes, and played important roles in cancer biological processes. Elucidation of proteasome alterations across multiple cancer types will directly contribute to cancer medical services in the context of predictive, preventive, and personalized medicine (PPPM / 3P medicine).

Purpose

This study aimed to investigate proteasome gene alterations across 33 cancer types for discovery of effective biomarkers and therapeutic targets in the framework of PPPM practice in cancers.

Methods

Proteasome gene data, including gene expression RNAseq, somatic mutation, tumor mutation burden (TMB), copy number variant (CNV), microsatellite instability (MSI) score, clinical characteristics, immune phenotype, 22 immune cells, cancer stemness index, drug sensitivity, and related pathways, were systematically analyzed with publically available database and bioinformatics across 11,057 patients with 33 cancer types.

Results

Differentially expressed proteasome genes were extensively found between tumor and control tissues. PSMB4 occurred the top mutation event among proteasome genes, and those proteasome genes were significantly associated with TMB and MSI score. Most of proteasome genes were positively related to CNV among single deletion, control copy number, and single gain. Kaplan-Meier curves and COX regression survival analysis showed proteasome genes were significantly associated with patient survival rate across 33 cancer types. Furthermore, the expressions of proteasome genes were significantly different among different clinical stages and immune subtypes. The expressions of proteasome genes were correlated with immune-related scores (ImmuneScore, StromalScore, and ESTIMATEScore), 22 immune cells, and cancer stemness. The sensitivities of multiple drugs were closely related to proteasome gene expressions. The identified proteasome and proteasome-interacted proteins were significantly enriched in various cancer-related pathways.

Conclusions

This study provided the first landscape of proteasome alterations across 11,057 patients with 33 cancer types and revealed that proteasome played a significant and wide functional role in cancer biological processes. These findings are the precious scientific data to reveal the common and specific alterations of proteasome genes among 33 cancer types, which benefits the research and practice of PPPM in cancers.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-021-00256-z.

Deubiquitinase PSMD14 promotes ovarian cancer progression by decreasing enzymatic activity of PKM2

Dysregulation of deubiquitination has been reported to contribute to carcinogenesis. However, the function and mechanism of deubiquitinating enzyme 26S proteasome non-ATPase regulatory subunit 14 (PSMD14) in the progression of ovarian cancer (OV), the deadliest gynecological cancer, still remains to be characterized. The present study demonstrated that PSMD14 was overexpressed in OV tissues and its higher levels correlated with a higher International Federation of Gynecology and Obstetrics (FIGO) stage in OV patients. A high level of PSMD14 expression was related to poor survival in OV patients. Knockdown and overexpression experiments elucidated that PSMD14 stimulated OV cell proliferation, invasion, and migration in vitro. Repression of PSMD14 suppressed OV tumor growth in vivo. PSMD14 inhibitor O-phenanthroline (OPA) effectively attenuated malignant behaviors of OV cells in vitro and OV tumor growth in vivo. Mechanistically, we uncovered that PSMD14 was involved in post-translational regulation of pyruvate kinase M2 isoform (PKM2). PSMD14 decreased K63-linked ubiquitination on PKM2, downregulated the ratio of PKM2 tetramers to dimers and monomers, and subsequently diminished pyruvate kinase activity and induced nuclear translocation of PKM2, contributing to aerobic glycolysis in OV cells. Collectively, our findings highlight the potential roles of PSMD14 as a biomarker and therapeutic candidate for OV.

USP24 promotes drug resistance during cancer therapy

Drug resistance has remained an important issue in the treatment and prevention of various diseases, including cancer. Herein, we found that USP24 not only repressed DNA-damage repair (DDR) activity by decreasing Rad51 expression to cause the tumor genomic instability and cancer stemness, but also increased the levels of the ATP-binding cassette (ABC) transporters P-gp, ABCG2, and ezrin to enhance the pumping out of Taxol from cancer cells, thus resulted in drug resistance during cancer therapy. A novel USP24 inhibitor, NCI677397, was screened for specific inhibiting the catalytic activity of USP24. This inhibitor was identified to suppress drug resistance via decreasing genomic instability, cancer stemness, and the pumping out of drugs from cancer cells. Understanding the role and molecular mechanisms of USP24 in drug resistance will be beneficial for the future development of a novel USP24 inhibitor. Our studies provide a new insight of USP24 inhibitor for clinically implication of blocking drug resistance during chemotherapy.

Advances in deubiquitinating enzymes in lung adenocarcinoma

The process of ubiquitination and deubiquitination is widely present in the human body's protein reactions and plays versatile roles in multiple diseases. Deubiquitinating enzymes (DUBs) are significant regulators of this process, which cleave the ubiquitin (Ub) moiety from various substrates and maintain protein stability. Lung adenocarcinoma (LUAD) is the most common type of non-small cell lung cancer (NSCLC) and remains refractory to treatment. To elucidate the mechanism of LUAD and advance new therapeutic targets, we review the latest research progress on DUBs in LUAD. We summarize the biological capabilities of these DUBs and further highlight those DUBs that may serve as anticancer target candidates for precision treatment. We also discuss deubiquitinase inhibitors, which are expected to play a role in targeted LUAD therapy.

The Role of BMP Signaling in Endothelial Heterogeneity

Bone morphogenetic proteins (BMPs), which compose the largest group of the transforming growth factor-β (TGF-ß) superfamily, have been implied to play a crucial role in diverse physiological processes. The most intriguing feature of BMP signaling is that it elicits heterogeneous responses from cells with equivalent identity, thus permitting highly context-dependent signaling outcomes. In endothelial cells (ECs), which are increasingly perceived as a highly heterogeneous population of cells with respect to their morphology, function, as well as molecular characteristics, BMP signaling has shown to elicit diverse and often opposite effects, illustrating the innate complexity of signaling responses. In this review, we provide a concise yet comprehensive overview of how outcomes of BMP signaling are modulated in a context-dependent manner with an emphasis on the underlying molecular mechanisms and summarize how these regulations of the BMP signaling promote endothelial heterogeneity.

Ubiquitin Specific Protease 29 Functions as an Oncogene Promoting Tumorigenesis in Colorectal Carcinoma

Simple Summary

Among other cancers, colorectal carcinoma (CRC) is one of the foremost causes of death worldwide. The mortality rate of those having CRC has increased dramatically in the past few years. Identification of novel regulatory molecules contributing to the progression of CRC remains a focus of significant interest. The oncogenic role of USP29 has recently been explored in a few cancer types. However, evidence concerning the expression of USP29 in other cancers is currently lacking. We identified that USP29 is highly expressed in CRC and may contribute to the progression of CRC. Depletion of USP29 in HCT116 by CRISPR-Cas9 system reduced the growth of cancer cells. Furthermore, our data suggests that USP29 knockdown reduced the tumor volume of mouse xenograft models. Future investigations are required to validate the outcome of USP29-targted therapy in patients having CRC.

Abstract

Colorectal carcinoma is the third foremost cause of cancer-related deaths and accounts for 5.8% of all deaths globally. The molecular mechanisms of colon cancer progression and metastasis control are not well studied. Ubiquitin-specific protease 29 (USP29), a deubiquitinating enzyme, is involved in the occurrence and development of wide variety of cancers. However, its clinical significance and biological roles in colorectal carcinoma (CRC) remain unexplored. In this research, we observed that the rate of USP29 overexpression was higher in colon cancer patient tissues relative to its corresponding normal tissues. CRISPR-Cas9-mediated depletion of USP29 triggered DNA double strand breaks and delayed cell-cycle progression in HCT116 cells. We also demonstrated that USP29 depletion hampers the colony formation and increases apoptosis of HCT116 cells. USP29 knockdown significantly decreased CRC cell proliferation in vitro. Depletion of USP29 in HCT116 cells substantially reduced the tumor volume of mouse xenografts. In conclusion, our study shows that elevated expression of USP29 promotes malignancy in CRC, suggesting that USP29 could be a promising target for colon cancer therapy.

The PSMD14 inhibitor Thiolutin as a novel therapeutic approach for esophageal squamous cell carcinoma through facilitating SNAIL degradation

Metastasis and chemoresistance are major causes of poor prognosis in patients with esophageal squamous cell carcinoma (ESCC), manipulated by multiple factors including deubiquitinating enzyme (DUB). DUB PSMD14 is reported to be a promising therapeutic target in various cancers. Here, we explored the antitumor activity of Thiolutin (THL), the PSMD14 inhibitor, as a new therapy strategy in ESCC.

Methods: Through 4-NQO-induced murine ESCC model, we investigated the expression of PSMD14 in esophageal tumorigenesis. Ubiquitin-AMC assay was performed to evaluate DUB activity of PSMD14 with THL treatment. The effect of THL on epithelial-to-mesenchymal transition (EMT), invasion, stemness and chemosensitivity was detected by using in vitro and in vivo experiments. Immunoprecipitation and in vivo ubiquitination assay were conducted to examine whether THL could impair the deubiquitination and stability of SNAIL regulated by PSMD14.

Results: Compared with normal esophageal epithelium, PSMD14 was upregulated in 4-NQO-induced murine esophageal epithelium dysplasia and ESCC tissues. THL could significantly weaken DUB activity of PSMD14. Furthermore, the results of in vitro and in vivo assays showed that THL efficiently suppressed motility and stemness and increased sensitivity to cisplatin in ESCC. Mechanically, THL impaired the interaction between PSMD14 and SNAIL, then promoted the ubiquitination and degradation of SNAIL to inhibit EMT which plays a crucial role in ESCC metastasis, stemness and chemosensitivity. TCGA database analysis revealed that high concomitant PSMD14/SNAIL expression predicted shorter overall survival in esophageal cancer.

Conclusion: Our findings demonstrate for the first time that suppression of PSMD14/SNAIL axis by THL could be a novel and promising therapeutic approach for ESCC clinical therapy.

Role of the BMP6 protein in breast cancer and other types of cancer

The BMP6 protein (Bone Morphogenetic Protein 6) is part of the superfamily of transforming growth factor-beta (TGF-β) ligands, participates in iron homeostasis, inhibits invasion by increasing adhesions and cell-cell type interactions and induces angiogenesis directly on vascular endothelial cells. BMP6 is coded by a tumor suppressor gene whose subexpression is related to the development and cancer progression; during neoplastic processes, methylation is the main mechanism by which gene silencing occurs. This work presents a review on the role of BMP6 protein in breast cancer (BC) and other types of cancer. The studies carried out to date suggest the participation of the BMP6 protein in the epithelial-mesenchymal transition (EMT) phenotype, cell growth and proliferation; however, these processes are affected in a variable way in the different types of cancer, the methylated CpG sites in BMP6 gene promoter, as well as the interaction with other proteins could be the cause of such variation.

Blockade of deubiquitinating enzyme PSMD14 overcomes chemoresistance in head and neck squamous cell carcinoma by antagonizing E2F1/Akt/SOX2-mediated stemness

Increasing evidence reveals a close relationship between deubiquitinating enzymes (DUBs) and cancer progression. In this study, we attempted to identify the roles and mechanisms of critical DUBs in head and neck squamous cell carcinoma (HNSCC).

Methods: Bioinformatics analysis was performed to screen differentially expressed novel DUBs in HNSCC. Immunohistochemistry assay was used to measure the expression of DUB PSMD14 in HNSCC specimens and adjacent normal tissues. The level of PSMD14 in HNSCC tumorigenesis was investigated using a 4-NQO-induced murine HNSCC model. The function of PSMD14 was determined through loss-of-function assays. Chromatin immunoprecipitation, immunoprecipitation and in vivo ubiquitination assay were conducted to explore the potential mechanism of PSMD14. The anti-tumor activity of PSMD14 inhibitor Thiolutin was assessed by in vitro and in vivo experiments.

Results: We identified PSMD14 as one of significantly upregulated DUBs in HNSCC tissues. Aberrant expression of PSMD14 was associated with tumorigenesis and malignant progression of HNSCC and further indicated poor prognosis. The results of in vitro and in vivo experiments demonstrated PSMD14 depletion significantly undermined HNSCC growth, chemoresistance and stemness. Mechanically, PSMD14 inhibited the ubiquitination and degradation of E2F1 to improve the activation of Akt pathway and the transcription of SOX2. Furthermore, PSMD14 inhibitor Thiolutin exhibited a potent anti-tumor effect on HNSCC in vivo and in vitro by impairing DUB activity of PSMD14.

Conclusion: Our findings demonstrate the role and mechanism of PSMD14 in HNSCC, and provide a novel and promising target for diagnosis and clinical therapy of HNSCC.

SMURF1, a promoter of tumor cell progression?

Overexpression of HECT-type E3 ubiquitin ligase SMURF1 is correlated with poor prognosis in patients with various cancers, such as glioblastoma, colon cancer, and clear cell renal cell carcinoma. SMURF1 acts as a tumor promoter by ubiquitination modification and/or degradation of tumor-suppressing proteins. Combined treatment of Smurf1 knockdown with rapamycin showed collaborative antitumor effects in mice. This review described the role of HECT, WW, and C2 domains in regulating SMURF1 substrate selection. We summarized up to date SMURF1 substrates regulating different type cell signaling, thus, accelerating tumor progression, invasion, and metastasis. Furthermore, the downregulation of SMURF1 expression, inhibition of its E3 activity and regulation of its specificity to substrates prevent tumor progression. The potential application of SMURF1 regulators, specifically, wisely choose certain drugs by blocking SMURF1 selectivity in tumor suppressors, to develop novel anticancer treatments.

The Deubiquitinating Enzyme USP20 Regulates the TNFα-Induced NF-κB Signaling Pathway through Stabilization of p62

p62/sequestosome-1 is a scaffolding protein involved in diverse cellular processes such as autophagy, oxidative stress, cell survival and death. It has been identified to interact with atypical protein kinase Cs (aPKCs), linking these kinases to NF-κB activation by tumor necrosis factor α (TNFα). The diverse functions of p62 are regulated through post-translational modifications of several domains within p62. Among the enzymes that mediate these post-translational modifications, little is known about the deubiquitinating enzymes (DUBs) that remove ubiquitin chains from p62, compared to the E3 ligases involved in p62 ubiquitination. In this study, we first demonstrate a role of ubiquitin-specific protease USP20 in regulating p62 stability in TNFα-mediated NF-κB activation. USP20 specifically binds to p62 and acts as a positive regulator for NF-κB activation by TNFα through deubiquitinating lysine 48 (K48)-linked polyubiquitination, eventually contributing to cell survival. Furthermore, depletion of USP20 disrupts formation of the atypical PKCζ-RIPK1-p62 complex required for TNFα-mediated NF-κB activation and significantly increases the apoptosis induced by TNFα plus cycloheximide or TNFα plus TAK1 inhibitor. These findings strongly suggest that the USP20-p62 axis plays an essential role in NF-κB-mediated cell survival induced by the TNFα-atypical PKCζ signaling pathway.