De-Ubiquitinating Enzymes USP21 Regulate MAPK1 Expression by Binding to Transcription Factor GATA3 to Regulate Tumor Growth and Cell Stemness of Gastric Cancer

USP21-mediated G3BP1 stabilization accelerates proliferation and metastasis of esophageal squamous cell carcinoma via activating Wnt/β-Catenin signaling

Lacking effective therapeutic targets heavily restricts the improvement of clinical prognosis for patients diagnosed with esophageal squamous cell carcinoma (ESCC). Ubiquitin Specific Peptidase 21 (USP21) is dysregulated in plenty of human cancers, however, its potential function and relevant molecular mechanisms in ESCC malignant progression as well as its value in clinical translation remain largely unknown. Here, in vitro and in vivo experiments revealed that aberrant upregulation of USP21 accelerated the proliferation and metastasis of ESCC in a deubiquitinase-dependent manner. Mechanistically, we found that USP21 binds to, deubiquitinates, and stabilizes the G3BP Stress Granule Assembly Factor 1 (G3BP1) protein, which is required for USP21-mediated ESCC progression. Further molecular studies demonstrated that the USP21/G3BP1 axis played a tumor-promoting role in ESCC progression by activating the Wnt/β-Catenin signaling pathway. Additionally, disulfiram (DSF), an inhibitor against USP21 deubiquitylation activity, markedly abolished the USP21-mediated stability of G3BP1 protein and significantly displayed an anti-tumor effect on USP21-driving ESCC progression. Finally, the regulatory axis of USP21/G3BP1 was demonstrated to be aberrantly activated in ESCC tumor tissues and closely associated with advanced clinical stages and unfavorable prognoses, which provides a promising therapeutic strategy targeting USP21/G3BP1 axis for ESCC patients.

Ubiquitin-specific protease 21 promotes tumorigenicity and stemness of colorectal cancer by deubiquitinating and stabilizing ZEB1

BACKGROUND

Colorectal cancer (CRC) is one very usual tumor together with higher death rate. Ubiquitin-specific protease 21 (USP21) has been confirmed to take part into the regulation of CRC progression through serving as a facilitator. Interestingly, the promotive function of USP21 has also discovered in the progression of CRC. ZEB1 has illustrated to be modulated by USP7, USP22 and USP51 in cancers. However, the regulatory functions of USP21 on ZEB1 in CRC progression need more investigations.

AIM

To investigate the relationship between USP21 and ZEB1 in CRC progression.

METHODS

The mRNA and protein expressions were assessed through RT-qPCR, western blot and IHC assay. The interaction between USP21 and ZEB1 was evaluated through Co-IP and GST pull down assays. The cell proliferation was detected through colony formation assay. The cell migration and invasion abilities were determined through Transwell assay. The stemness was tested through sphere formation assay. The tumor growth was evaluated through in vivo mice assay.

RESULTS

In this work, USP21 and ZEB1 exhibited higher expression in CRC, and resulted into poor prognosis. Moreover, the interaction between USP21 and ZEB1 was further investigated. It was demonstrated that USP21 contributed to the stability of ZEB1 through modulating ubiquitination level. In addition, USP21 strengthened cell proliferation, migration and stemness through regulating ZEB1. At last, through in vivo assays, it was illustrated that USP21/ZEB1 axis aggravated tumor growth.

CONCLUSION

For the first time, these above findings manifested that USP21 promoted tumorigenicity and stemness of CRC by deubiquitinating and stabilizing ZEB1. This discovery suggested that USP21/ZEB1 axis may provide novel sights for the treatment of CRC.

Inhibition of USP21 leads to ovarian carcinoma cell death by suppressing MAPK signaling

Ovarian cancer is the most aggressive and lethal of all gynecologic malignancies. Although the overexpression (OE) of ubiquitin-specific peptidase 21 (USP21) has been observed in multiple cancers, its expression profile and biological function in ovarian cancer remain unknown. The expression levels of USP21 in ovarian cancer cells and tissues as well as adjacent normal tissues were assessed by qRT-PCR or Western blot assay. The biological function of USP21 in ovarian cancer cells was assessed by cell growth assay in vitro and a tumor growth model in vivo. Our study revealed that USP21 was markedly elevated in ovarian carcinoma tissues compared with adjacent normal tissues. Downregulation of USP21 attenuated the expression levels of MEK2 and p-ERK1/2. Depletion of USP21 resulted in suppressed cell growth of ovarian cancers in vitro and inhibited tumor growth in vivo. Conversely, OE of USP21 promoted the cell proliferation of ovarian cancers and conferred resistance to BAY 11-7082. These findings provide evidences supporting the notion of USP21 as a promising therapeutic target for the treatment of ovarian cancer.

Emerging role of deubiquitination modifications of programmed death-ligand 1 in cancer immunotherapy

Immune evasion is essential for carcinogenesis and cancer progression. Programmed death-ligand 1 (PD-L1), a critical immune checkpoint molecule, interacts with programmed death receptor-1 (PD-1) on immune cells to suppress anti-tumor immune responses. In the past decade, antibodies targeting PD-1/PD-L1 have tremendously altered cancer treatment paradigms. Post-translational modifications have been reported as key regulators of PD-L1 expression. Among these modifications, ubiquitination and deubiquitination are reversible processes that dynamically control protein degradation and stabilization. Deubiquitinating enzymes (DUBs) are responsible for deubiquitination and have emerged as crucial players in tumor growth, progression, and immune evasion. Recently, studies have highlighted the participation of DUBs in deubiquitinating PD-L1 and modulating its expression. Here, we review the recent developments in deubiquitination modifications of PD-L1 and focus on the underlying mechanisms and effects on anti-tumor immunity.

USP21 contributes to the aggressiveness of laryngeal cancer cells by deubiquitinating and stabilizing AURKA

Laryngeal cancer is a usual malignant tumor of the head and neck. The role and mechanism of deubiquitinase USP21 in laryngeal cancer are still unclear. We aimed to explore whether USP21 affected laryngeal cancer progress through deubiquitinating AURKA. USP21 and AURKA levels were evaluated by qRT-PCR and Western blot. Kaplan-Meier analysis was conducted by survival package. MTT was performed to detect cell proliferation. The wound healing assay was applied to evaluate cell migration. Transwell was used to measure cell invasion. Co-IP and GST-pull down determined the interaction between USP21 and AURKA. In addition, AURKA ubiquitination levels were analyzed. USP21 was signally elevated in laryngeal cancer tissues and cells. USP21 level in clinical stages III-IV was higher than that in clinical stages I-II, and high levels of USP21 were highly correlated with poor prognosis in laryngeal cancer. USP21 inhibition suppressed AMC-HN-8 and TU686 cell proliferation, migration and invasion. Co-IP and GST-pull down confirmed the interaction between USP21 and AURKA. Knockdown of USP21 markedly increased the ubiquitination level of AURKA, and USP21 restored AURKA activity through deubiquitination. In addition, overexpression of AURKA reversed the effects of USP21 knockdown on cell growth, migration, and invasion. USP21 stabilized AURKA through deubiquitination to promote laryngeal cancer progression.

Discovery and Characterization of BAY-805, a Potent and Selective Inhibitor of Ubiquitin-Specific Protease USP21

USP21 belongs to the ubiquitin-specific protease (USP) subfamily of deubiquitinating enzymes (DUBs). Due to its relevance in tumor development and growth, USP21 has been reported as a promising novel therapeutic target for cancer treatment. Herein, we present the discovery of the first highly potent and selective USP21 inhibitor. Following high-throughput screening and subsequent structure-based optimization, we identified BAY-805 to be a non-covalent inhibitor with low nanomolar affinity for USP21 and high selectivity over other DUB targets as well as kinases, proteases, and other common off-targets. Furthermore, surface plasmon resonance (SPR) and cellular thermal shift assays (CETSA) demonstrated high-affinity target engagement of BAY-805, resulting in strong NF-κB activation in a cell-based reporter assay. To the best of our knowledge, BAY-805 is the first potent and selective USP21 inhibitor and represents a valuable high-quality in vitro chemical probe to further explore the complex biology of USP21.

Salt-like transcription factor 4 promotes laryngeal cancer progression through transcriptional activation of ubiquitin-specific protease 21 to stabilize Yin Yang 1

Laryngeal cancer (LC) is a rare and challenging clinical problem. Our aim was to investigate the mechanism of salt-like transcription factor 4 (SALL4) in LC. LC tissue and paracancerous tissue were collected. Relative mRNA or protein levels were measured by quantitative real-time polymerase chain reaction or Western blot. MTT, wound healing, and transwell assay were performed to evaluate cell proliferation, migration and invasion. The binding relationship between SALL4 and USP21 promoter was verified by dual-luciferase assay and ChIP. Co-IP and glutathione-S-transferase (GST)-pull down were performed to measure the protein interaction between USP21 and YY1. Additionally, YY1 ubiquitination level was analyzed. It was found that SALL4 mRNA and SALL4 protein levels were elevated in LC clinical tissues and various LC cells. Knockdown of SALL4 inhibited epithelial-mesenchymal transition (EMT) of LC cells. USP21 was transcriptionally activated by SALL4. Co-IP and GST-pull down confirmed USP21 interacted with YY1. USP21 protected YY1 from degradation through deubiquitination. Furthermore, overexpression of USP21 reversed the effect of knockdown of SALL4 on YY1 and EMT in LC cells. In general, SALL4 facilitated EMT of LC cells through modulating USP21/YY1 axis.

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.

Investigating the Active Substance and Mechanism of San-Jiu-Wei-Tai Granules via UPLC-QE-Orbitrap-MS and Network Pharmacology

San-Jiu-Wei-Tai granules (SJWTG) are a significant Chinese patent medicine for the treatment of chronic gastritis (CG), having outstanding advantages in long-term treatment; however, the chemical composition and potential mechanism have not been investigated until now. In this study, a rapid separation and identification method based on UPLC-QE-Orbitrap-MS was established, and 95 chemical components from SJWTGs were identified, including 6 chemical components of an unknown source that are not derived from the 8 herbs included in SJWTGs. The identified chemical components were subsequently analysed by network pharmacology, suggesting that the core targets for the treatment of CG with SJWTGs were EGFR, SRC, AKT1, HSP90AA1, MAPK1, and MAPK3 and thus indicating that SJWTGs could reduce the inflammatory response of gastric epithelial cells and prevent persistent chronic inflammation that induces cancerization by regulating the MAPK signalling pathway and the C-type lectin receptor signalling pathway as well as their upstream and downstream pathways in the treatment of CG. The key bioactive components in SJWTGs were identified as 2,6-bis(4-ethylphenyl)perhydro-1,3,5,7-tetraoxanaphth-4-ylethane-1,2-diol, a chemical component of an unknown source, murrangatin, meranzin hydrate, paeoniflorin, and albiflorin. The results of molecular docking showed the strong binding interaction between the key bioactive components and the core targets, demonstrating that the key bioactive components deserve to be further studied and considered as Q-markers. By acting on multiple targets, SJWTG is less susceptible to drug resistance during the long-term treatment of CG, indicating the advantage of Chinese patent medicines. Furthermore, the preventive effect of SJWTGs on gastric cancer also demonstrates the superiority of preventive treatment of disease with traditional Chinese medicine.

MiR-585-5p impedes gastric cancer proliferation and metastasis by orchestrating the interactions among CREB1, MAPK1 and MITF

Background

Gastric cancer (GC) is one of the most malignant and lethal cancers worldwide. Multiple microRNAs (miRNAs) have been identified as key regulators in the progression of GC. However, the underlying pathogenesis that miRNAs govern GC malignancy remains uncertain. Here, we identified a novel miR-585-5p as a key regulator in GC development.

Methods

The expression of miR-585-5p in the context of GC tissue was detected by in situ hybridization for GC tissue microarray and assessed by H-scoring. The gain- and loss-of-function analyses comprised of Cell Counting Kit-8 assay and Transwell invasion and migration assay. The expression of downstream microphthalmia-associated transcription factor (MITF), cyclic AMP-responsive element-binding protein 1 (CREB1) and mitogen-activated protein kinase 1 (MAPK1) were examined by Immunohistochemistry, quantitative real-time PCR and western blot. The direct regulation between miR-585-5p and MITF/CREB1/MAPK1 were predicted by bioinformatic analysis and screened by luciferase reporter assay. The direct transcriptional activation of CREB1 on MITF was verified by luciferase reporter assay, chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift assays (EMSAs). The interaction between MAPK1 and MITF was confirmed by co-immunoprecipitation (Co-IP) and immunofluorescent double-labelled staining.

Results

MiR-585-5p is progressively downregulated in GC tissues and low miR-585-5p levels were strongly associated with poor clinical outcomes. Further gain- and loss-of-function analyses showed that miR-585-5p possesses strong anti-proliferative and anti-metastatic capacities in GC. Follow-up studies indicated that miR-585-5p targets the downstream molecules CREB1 and MAPK1 to regulate the transcriptional and post-translational regulation of MITF, respectively, thus controlling its expression and cancer-promoting activity. MiR-585-5p directly and negatively regulates MITF together with CREB1 and MAPK1. According to bioinformatic analysis, promotor reporter gene assays, ChIP and EMSAs, CREB1 binds to the promotor region to enhance transcriptional expression of MITF. Co-IP and immunofluorescent double-labelled staining confirmed interaction between MAPK1 and MITF. Protein immunoprecipitation revealed that MAPK1 enhances MITF activity via phosphorylation (Ser73). MiR-585-5p can not only inhibit MITF expression directly, but also hinder MITF expression and pro-cancerous activity in a CREB1-/MAPK1-dependent manner indirectly.

Conclusions

In conclusion, this study uncovered miR-585-5p impedes gastric cancer proliferation and metastasis by orchestrating the interactions among CREB1, MAPK1 and MITF.

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.

MZF1 Transcriptionally Activated MicroRNA-328-3p Suppresses the Malignancy of Stomach Adenocarcinoma via Inhibiting CD44

MicroRNA-328-3p (miR-328-3p) plays a critical role in mediating the progression of multiple types of cancers. To date, no study has concentrated on the molecular mechanism of miR-328-3p in mediating stomach adenocarcinoma (STAD). In this study, it was found that miR-328-3p was downregulated in STAD, and inhibition of miR-328-3p significantly promoted the growth, migration, invasion, and stemness of STAD cells, while miR-328-3p overexpression exerted reverse effects. Through bioinformatics analysis, it was uncovered that a cluster of differentiation 44 (CD44) was upregulated in STAD and closely associated with the prognosis of STAD patients. Mechanistically, we identified CD44 as the target gene of miR-328-3p. Notably, knockdown of CD44 abolished the promoting function of miR-328-3p inhibitor in the development of STAD. Moreover, myeloid zinc finger protein 1 (MZF1) was confirmed as an upstream transcription factor for miR-328-3p, which is involved in enhancing miR-328-3p expression. In addition, the role of MZF1 downregulation in the malignant traits of STAD cells was blocked by miR-328-3p overexpression. More importantly, upregulation of miR-328-3p efficiently suppressed STAD tumor growth in vivo. Collectively, our findings illustrated that MZF1-mediated miR-328-3p acted as a cancer suppressor in STAD progression via regulation of CD44, which suggested the possibility of the MZF1/miR-328-3p/CD44 axis as a novel promising therapeutic candidate for STAD.

Network Pharmacology Analysis of Huangqi Jianzhong Tang Targets in Gastric Cancer

Background: The Chinese medicine, Huangqi Jianzhong Tang (HJT), is widely used to treat gastric cancer (GC). In this study, network pharmacological methods were used to analyze the potential therapeutic targets and pharmacological mechanisms of HJT in GC.

Methods: Bioactive components and targets of HJT and GC-related targets were identified using public databases. The protein-protein interaction network of potential targets of HJT in GC was constructed using the Cytoscape plug-in (v3.8.0), CytoHubba. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were performed, in addition to molecular docking and animal experiments to verify the results of network pharmacology analysis.

Results: A total of 538 GC-related targets were identified. The bioactive components of HJT were selected for drug-likeness evaluation and binomial statistical model screening, which revealed 63 bioactive components and 72 targets. Based on GO enrichment analysis, all targets in the protein-protein interaction network were mainly involved in the response to oxidative stress and neuronal death. Further, KEGG enrichment analysis suggested that the treatment of GC with HJT mainly involved the Wnt signaling pathway, PI3K-Akt signaling pathway, TGF-β signaling pathway, and MAPK signaling pathway, thereby providing insights into the mechanism of the effects of HJT on GC.

Conclusion: This study revealed the potential bioactive components and molecular mechanisms of HJT, which may be useful for the treatment of GC, and provided insights into the development of new drugs for GC.

Identification of a Novel Immune-Related lncRNA CTD-2288O8.1 Regulating Cisplatin Resistance in Ovarian Cancer Based on Integrated Analysis

Ovarian cancer (OC) is the most lethal gynecological malignancy, in which chemoresistance is a crucial factor leading to the poor prognosis. Recently, immunotherapy has brought new light for the treatment of solid tumors. Hence, as a kind of immunologically active cancer, it is reasonably necessary to explore the potential mechanism between immune characteristics and cisplatin resistance in OC. Our study focused on the important role of cisplatin resistance-related lncRNAs on mediating the OC tumor immune microenvironment (TIME) using an integrative analysis based on the Cancer Genome Atlas (TCGA) database. First, the cisplatin resistance-related differentially expressed lncRNAs (DELs) and mRNAs (DEMs) were preliminarily screened to construct a DEL–DEM co-expression network. Next, the protein–protein interaction (PPI) network and pivot analysis were performed to reveal the relevance of these lncRNAs with tumor immune response. Second, the novel lncRNA CTD-2288O8.1 was identified as a key gene for the OC cisplatin resistance formation by qRT-PCR and survival analysis. Gain- and loss-of-function assays (Cell Counting Kit-8 (CCK-8) assay, wound-healing scratch assay, transwell assay, and colony formation assay) further verified the activity of CTD-2288O8.1 in OC progression as well. Third, gene set enrichment analysis (GSEA) was applied along with the correlation analyses of CTD-2288O8.1 with ImmuneScore, tumor-infiltrating immune cells (TICs), and immune inhibitory checkpoint molecules, illustrating that CTD-2288O8.1 was strongly associated with the TIME and has the potential to predict the effect of OC immunotherapy. In addition, basic experiments demonstrated that the expression of CTD-2288O8.1 impacted the EGFR/AKT signal pathway activity of OC tumor cells. Of greater significance, it promoted the M2 polarization of macrophage, which is a type of the most important components of the TIME in solid tumor. Taking together, our study revealed cisplatin resistance-related lncRNAs closely linked with tumor immunity in OC, underscoring the potential mechanism of the TIME in conferring cisplatin resistance, which provided the research basis for further clinical treatment. CTD-2288O8.1 was identified to mediate cisplatin resistance and affect the response of immunotherapy, which could serve as a promising biomarker for guiding clinical treatment and improving prognosis in OC.

Tripartite motif-containing 54 promotes gastric cancer progression by upregulating K63-linked ubiquitination of filamin C

BACKGROUND

Tripartite motif (TRIM) proteins have been proved to contribute to cancer progression, while whether tripartite motif-containing 54 (TRIM54) could functionally influence gastric cancer (GC) progression remains elusive.

METHODS

The expression level of TRIM54 and filamin C (FLNC) in GC was determined by Western blot and online database. Cell Counting Kit-8 (CCK-8) assay, colony formation assay and Ethylenediurea (EdU) staining were performed to explore the effects of TRIM54 on GC cell proliferation. Transwell assay and wound healing assay were applied to detect the influence of TRIM54 on GC cell migration and invasion. Bioinformatics analysis and Co-immunoprecipitation assay (Co-Ip), Ubiquitination assay and Half-life assay were involved to explore the regulatory mechanism of TRIM54 on FLNC.

RESULTS

TRIM54 was upregulated in GC tissues and cells, and a higher expression level of TRIM54 indicated a shorter overall survival of GC patients. The overexpression of TRIM54 significantly enhanced proliferation, migration, and invasion of GC cells, and inhibition of TRIM54 expression exerted reverse effects on GC cells. Mechanistically, TRIM54 was determined as a post-translational mediator of FLNC, and TRIM54 was co-immunoprecipitated with FLNC and degraded its protein level via K63-linked ubiquitination of FLNC. Notably, FLNC efficiently inhibited GC progression by TRIM54 overexpression.

CONCLUSION

Collectively, our findings suggested that the TRIM54/FLNC axis could be considered as a potential prognostic biomarker for GC.