USP22 promotes tumor progression and induces epithelial-mesenchymal transition in lung adenocarcinoma

Mogrol-mediated enhancement of radiotherapy sensitivity in non-small cell lung cancer: a mechanistic study

This study investigated mogrol's impact on non-small cell lung cancer (NSCLC) radiosensitivity and underlying mechanisms, using various methods including assays, bioinformatics, and xenograft models. CCK-8, clonogenic, flow cytometry, TUNEL, and Western blot assays evaluated mogrol and radiation effects on NSCLC viability and apoptosis. Ubiquitin-specific protease 22 (USP22) expression in NSCLC patient tissues was determined by RT-qPCR and Western blot. A xenograft model validated mogrol's effects on tumor growth. Bioinformatics identified four ubiquitin-specific proteases, including USP22, in NSCLC. Kaplan-Meier analysis confirmed USP22's value in lung cancer survival. Human Protein Atlas (HPA) database analysis indicated higher USP22 expression in lung cancer tissues. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis implicated ERK1/2 in NSCLC progression, and molecular docking showed stability between mogrol and ERK1/2. Further in vivo and in vitro experiments have demonstrated that mogrol enhances the inhibitory effect of radiation on NSCLC cell viability and clonogenic capacity. Cell viability and clonogenic capacity are reduced by >50%, and an increase in cellular apoptosis is observed, with apoptotic levels reaching 10%. USP22 expression was significantly elevated in NSCLC tissues, particularly in radiotherapy-resistant patients. Mogrol downregulated USP22 expression by inhibiting the ERK/CREB pathway, lowering COX2 expression. Mogrol also enhanced radiation's inhibition of tumor growth in mice. Mogrol enhances NSCLC radiosensitivity by downregulating USP22 via the ERK/CREB pathway, leading to reduced COX2 expression.NEW & NOTEWORTHY Mogrol enhances non-small cell lung cancer (NSCLC) cell sensitivity to radiotherapy by downregulating USP22 through the ERK/CREB pathway, reducing COX2 expression. These findings highlight mogrol's potential as an adjunct to improve NSCLC radiotherapy and open avenues for further research and clinical applications.

Programmed Death Ligand 1 Regulatory Crosstalk with Ubiquitination and Deubiquitination: Implications in Cancer Immunotherapy

Programmed death ligand 1 (PD-L1) plays a pivotal role in cancer immune evasion and is a critical target for cancer immunotherapy. This review focuses on the regulation of PD-L1 through the dynamic processes of ubiquitination and deubiquitination, which are crucial for its stability and function. Here, we explored the intricate mechanisms involving various E3 ubiquitin ligases and deubiquitinating enzymes (DUBs) that modulate PD-L1 expression in cancer cells. Specific ligases are discussed in detail, highlighting their roles in tagging PD-L1 for degradation. Furthermore, we discuss the actions of DUBs that stabilize PD-L1 by removing ubiquitin chains. The interplay of these enzymes not only dictates PD-L1 levels but also influences cancer progression and patient response to immunotherapies. Furthermore, we discuss the therapeutic implications of targeting these regulatory pathways and propose novel strategies to enhance the efficacy of PD-L1/PD-1-based therapies. Our review underscores the complexity of PD-L1 regulation and its significant impact on the tumor microenvironment and immunotherapy outcomes.

Construction of an immune predictive model and identification of TRIP6 as a prognostic marker and therapeutic target of CRC by integration of single-cell and bulk RNA-seq data

BACKGROUND

Investigations elucidating the complex immunological mechanisms involved in colorectal cancer (CRC) and accurately predicting patient outcomes via bulk RNA-Seq analysis have been notably limited. This study aimed to identify the immune status of CRC patients, construct a prognostic model, and identify prognostic signatures via bulk RNA sequencing (RNA-seq) and single-cell RNA-seq (scRNA-seq).

METHODS

The scRNA-seq data of CRC were downloaded from Gene Expression Omnibus (GEO). The UCSC Xena database was used to obtain bulk RNA-seq data. Differentially expressed gene (DEG), functional enrichment, and random forest analyses were conducted in order to identify core genes associated with colorectal cancer (CRC) that were relevant to prognosis. A molecular immune prediction model was developed using logistic regression after screening features using the least absolute shrinkage and selection operator (LASSO). The differences in immune cell infiltration, mutation, chemotherapeutic drug sensitivity, cellular senescence, and communication between patients who were at high and low risk of CRC according to the predictive model were investigated. The prognostic genes that were closely associated with CRC were identified by random survival forest (RSF) analysis. The expression levels and clinical significance of the hub genes were analyzed in vitro. The LoVo cell line was employed to ascertain the biological role of thyroid hormone receptor-interacting protein 6 (TRIP6).

RESULTS

A total of seven main cell subtypes were identified by scRNA-seq analysis. A molecular immune predictive model was constructed based on the risk scores. The risk score was significantly associated with OS, stage, mutation burden, immune cell infiltration, response to immunotherapy, key pathways, and cell-cell communication. The functions of the six hub genes were determined and further utilized to establish a regulatory network. Our findings unequivocally confirmed that TRIP6 upregulation was verified in the CRC samples. After knocking down TRIP6, cell proliferation, migration, and invasion of LoVo cells were inhibited, and apoptosis was promoted.

CONCLUSIONS

The molecular predictive model reliably distinguished the immune status of CRC patients. We further revealed that TRIP6 may act as an oncogene in CRC, making it a promising candidate for targeted therapy and as a prognostic marker for CRC.

Ubiquitin-specific protease 22 promotes tumorigenesis and progression by an FKBP12/mTORC1/autophagy positive feedback loop in hepatocellular carcinoma

Ubiquitin-specific protease 22 (USP22) has been identified as a potential marker for cancer stem cells in hepatocellular carcinoma (HCC). It can promote HCC stemness, which is considered a driver of tumorigenesis. Here, we sought to determine the role of USP22 in tumorigenesis, elucidate its underlying mechanism, and explore its therapeutic significance in HCC. As a result, we found that tissue-specific Usp22 overexpression accelerated tumorigenesis, whereas Usp22 ablation decelerated it in a c-Myc/NRasGV12-induced HCC mouse model and that the mammalian target of rapamycin complex 1 (mTORC1) pathway was activated downstream. USP22 overexpression resulted in increased tumorigenic properties that were reversed by rapamycin in vitro and in vivo. In addition, USP22 activated mTORC1 by deubiquitinating FK506-binding protein 12 (FKBP12) and activated mTORC1, in turn, further stabilizing USP22 by inhibiting autophagic degradation. Clinically, HCC patients with high USP22 expression tend to benefit from mTOR inhibitors after liver transplantation (LT). Our results revealed that USP22 promoted tumorigenesis and progression via an FKBP12/mTORC1/autophagy positive feedback loop in HCC. Clinically, USP22 may be an effective biomarker for selecting eligible recipients with HCC for anti-mTOR-based therapy after LT.

Single-cell RNA sequencing reveals small extracellular vesicles derived from malignant cells that contribute to angiogenesis in human breast cancers

BACKGROUND

Breast cancer is the most common cancer affecting women across the world. Tumor endothelial cells (TECs) and malignant cells are the major constituents of the tumor microenvironment (TME), but their origin and role in shaping disease initiation, progression, and treatment responses remain unclear due to significant heterogeneity.

METHODS

Tissue samples were collected from eight patients presenting with breast cancer. Single-cell RNA sequencing (scRNA-seq) analysis was employed to investigate the presence of distinct cell subsets in the tumor microenvironment. InferCNV was used to identify cancer cells. Pseudotime trajectory analysis revealed the dynamic process of breast cancer angiogenesis. We validated the function of small extracellular vesicles (sEVs)-derived protein phosphatase 1 regulatory inhibitor subunit 1B (PPP1R1B) in vitro experiments.

RESULTS

We performed single-cell transcriptomics analysis of the factors associated with breast cancer angiogenesis and identified twelve subclusters of endothelial cells involved in the tumor microenvironment. We also identified the role of TECs in tumor angiogenesis and confirmed their participation in different stages of angiogenesis, including communication with other cell types via sEVs. Overall, the research uncovered the TECs heterogeneity and the expression levels of genes at different stages of tumor angiogenesis.

CONCLUSIONS

This study showed sEVs derived from breast cancer malignant cells promote blood vessel formation by activating endothelial cells through the transfer of PPP1R1B. This provides a new direction for the development of anti-angiogenic therapies for human breast cancer.

USP22 aggravated diabetic renal tubulointerstitial fibrosis progression through deubiquitinating and stabilizing Snail1

Renal tubulointerstitial fibrosis (TIF) is one of the main pathological changes induced by diabetic kidney disease (DKD), and epithelial-to-mesenchymal transition (EMT) induced by high glucose (HG) can promote TIF. Our previous study has shown that ubiquitin-specific protease 22 (USP22) could affect the process of DKD by deubiquitinating and stabilizing Sirt1 in glomerular mesangial cells. However, whether USP22 could regulate EMT occurrence in renal tubular epithelial cells and further aggravate the pathological process of TIF in DKD remains to be elucidated. In this study, we found that USP22 expression was upregulated in kidney tissues of db/db mice and HG-treated NRK-52E cells. In vitro, USP22 overexpression promoted the EMT process of NRK-52E cells stimulated by HG and further increased the levels of extracellular matrix (ECM) components such as fibronectin, Collagen I, and Collagen Ⅳ. Meanwhile, USP22 deficiency exhibited the opposite effects. Mechanism studies showed that USP22, depending on its deubiquitinase activity, deubiquitinated and stabilized the EMT transcriptional factor Snail1. In vivo experiment showed that interfering with USP22 could improve the renal pathological damages and renal function of the db/db spontaneous diabetic mice by decreasing Snail1 expression, which could inhibit EMT occurrence, and reduce the production of ECM components. These results suggested that USP22 could accelerate renal EMT and promote the pathological progression of diabetic TIF by deubiquitinating Snail1, providing an experimental basis for using USP22 as a potential target for DKD.

USP22 Contributes to Chemoresistance, Stemness, and EMT Phenotype of Triple-Negative Breast Cancer Cells by egulating the Warburg Effect via c-Myc Deubiquitination

BACKGROUND

Ubiquitin-specific protease 22 (USP22) has been implicated in the progression of breast cancer, while its regulatory functions in triple-negative breast cancer (TNBC) have been rarely reported. This study aimed to elucidate the effect and mechanism of USP22 on the malignant phenotype of TNBC cells.

MATERIALS AND METHODS

The expression of USP22, stemness genes, and EMT-related markers were analyzed by RT-qPCR and/or Western blotting. Cell stemness was determined by cell spheroid formation, flow cytometry for CD44+/CD24-, and extreme limiting dilution analysis. Cell proliferation and cisplatin (DDP) chemoresistance of TNBC cells were assessed by CCK-8 assay and xenograft model. Glycolysis was measured by Seahorse assay. The mechanism underlying the role of USP22 was explored by Co-immunoprecipitation, ubiquitination assay, and cycloheximide-chase analysis.

RESULTS

USP22 expression was positively correlated with DDP resistance in TNBC patients and cells. The proliferation, spheroid number, CD44+/CD24- cells, the expression of stemness genes and EMT-related markers in TNBC cells were significantly elevated after USP22 was overexpressed; however, these parameters in DDP-resistant TNBC (TNBC/DDP) cells were significantly reduced after silencing USP22. USP22 overexpression enhanced the extracellular acidification rate, proliferation, spheroid number, CD44+/CD24- cell number, and the expression of stemness genes and EMT-related markers in TNBC/DDP cells, while these effects were restrained by glycolysis inhibitors. Mechanically, USP22 interacted with c-Myc to promote its stabilization by deubiquitination in TNBC cells. Silencing of USP22 increased DDP sensitivity and survival of mice bearing TNBC.

CONCLUSION

USP22 contributes to chemoresistance, stemness, and EMT phenotype of TNBC cells by suppressing the glycolysis via c-Myc deubiquitination.

Immune Evasion and Drug Resistance Mediated by USP22 in Cancer: Novel Targets and Mechanisms

Regulation of ubiquitination is involved in various processes in cancer occurrence and development, including cell cycle arrest, cell proliferation, apoptosis, invasion, metastasis, and immunity. Ubiquitination plays an important role not only at the transcriptional and post-translational levels but also at the protein level. When ubiquitination is in a pathological state, abnormally activated biological processes will not only induce cancer progression but also induce immune evasion. The main function of deubiquitinases (DUBs) is to remove ubiquitin chains from substrates, changing the biological activity of the substrates. It has great potential to improve the prognosis of cancer by targeting DUB to regulate proteome. Ubiquitin-specific peptidase 22 (USP22) belongs to the ubiquitin-specific protease (USP) family of DUBs and has been reported to be related to various physiological and pathological processes. USP22 is abnormally expressed in various malignant tumors such as prostate cancer, lung cancer, liver cancer, and colorectal cancer, which suggests that USP22 may play an important role in tumors. USP22 may stabilize programmed death ligand 1 (PD-L1) by deubiquitination while also regulating T-cell infiltration into tumors. Regulatory T cells (Tregs) are a unique class of immunosuppressive CD4⁺ T cells that primarily suppress the immune system by expressing the master transcription factor forkhead box protein 3 (FOXP3). USP22 was found to be a positive regulator of stable FOXP3 expression. Treg-specific ablation of USP22 leads to reduced tumor volume in multiple cancer models. This suggests that USP22 may regulate tumor resistance to immunotherapy. In this article, we review and summarize the biological functions of USP22 in multiple signal transduction pathways during tumorigenesis, immune evasion, and drug resistance. Furthermore, we propose a new possibility of combining USP22 with chemotherapeutic, targeted, and immunosuppressive drugs in the treatment of cancer.

The Ubiquitin System: An Emerging Therapeutic Target for Lung Cancer

The ubiquitin system, present in all eukaryotes, contributes to regulating multiple types of cellular protein processes such as cell signaling, cell cycle, and receptor trafficking, and it affects the immune response. In most types of cancer, unusual events in ubiquitin-mediated signaling pathway modulation can lead to a variety of clinical outcomes, including tumor formation and metastasis. Similarly, ubiquitination acts as a core component, which contributes to the alteration of cell signaling activity, dictating biosignal turnover and protein fates. As lung cancer acquires the most commonly mutated proteins, changes in the ubiquitination of the proteins contribute to the development of lung cancer. Various inhibitors targeting the ubiquitin system have been developed for clinical applications in lung cancer treatment. In this review, we summarize the current research advances in therapeutics for lung cancer by targeting the ubiquitin system.

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.

Deubiquitinating Enzymes Orchestrate the Cancer Stem Cell-Immunosuppressive Niche Dialogue: New Perspectives and Therapeutic Potential

Cancer stem cells (CSCs) are sparks for igniting tumor recurrence and the instigators of low response to immunotherapy and drug resistance. As one of the important components of tumor microenvironment, the tumor associated immune microenvironment (TAIM) is driving force for the heterogeneity, plasticity and evolution of CSCs. CSCs create the inhibitory TAIM (ITAIM) mainly through four stemness-related signals (SRSs), including Notch-nuclear factor-κB axis, Hedgehog, Wnt and signal transducer and activator of transcription. Ubiquitination and deubiquitination in proteins related to the specific stemness of the CSCs have a profound impact on the regulation of ITAIM. In regulating the balance between ubiquitination and deubiquitination, it is crucial for deubiquitinating enzymes (DUBs) to cleave ubiquitin chains from substrates. Ubiquitin-specific peptidases (USPs) comprise the largest family of DUBs. Growing evidence suggests that they play novel functions in contribution of ITAIM, including regulating tumor immunogenicity, activating stem cell factors, upregulating the SRSs, stabilizing anti-inflammatory receptors, and regulating anti-inflammatory cytokines. These overactive or abnormal signaling may dampen antitumor immune responses. The inhibition of USPs could play a regulatory role in SRSs and reversing ITAIM, and also have great potential in improving immune killing ability against tumor cells, including CSCs. In this review, we focus on the USPs involved in CSCs signaling pathways and regulating ITAIM, which are promising therapeutic targets in antitumor therapy.

Ubiquitin-specific peptidase 22 in cancer

Recently, many studies have shown that deubiquitination modification of proteins is of great significance in major physiological processes such as cell proliferation, apoptosis, and differentiation. The ubiquitin-specific peptidase (USP) family is one of the most numerous and structurally diverse of the deubiquitinates known to date. USP22, an important member of the USP family, has been found to be closely associated with tumor cell cycle regulation, stemness maintenance, invasion and metastasis, chemoresistance, and immune regulation. We focus on recent advances regarding USP22's function in cancer and discuss the prospect of USP22 in this review.

What deubiquitinating enzymes, oncogenes, and tumor suppressors actually do: Are current assumptions supported by patient outcomes?

Context can determine whether a given gene acts as an oncogene or a tumor suppressor. Deubiquitinating enzymes (DUBs) regulate the stability of many components of the pathways dictating cell fate so it would be expected that alterations in the levels or activity of these enzymes may have oncogenic or tumor suppressive consequences. In the current review we survey publications reporting that genes encoding DUBs are oncogenes or tumor suppressors. For many DUBs both claims have been made. For such "double agents," the effects of gain or loss of function will depend on the overall status of a complex of molecular signaling networks subject to extensive crosstalk. As the TGF-β paradox makes clear context is critical in cell fate decisions, and the disconnect between experimental findings and patient survival outcomes can in part be attributed to disparities between culture conditions and the microenvironment in vivo. Convincing claims for oncogene or tumor suppressor roles require the documentation of gene alterations in patient samples; survival curves are alone inadequate.

The POU2F1/miR-4490/USP22 axis regulates cell proliferation and metastasis in gastric cancer

PURPOSE

Growing evidence indicates that aberrant expression of microRNAs contributes to tumor development. However, the biological role of microRNA-4490 (miR-4490) in gastric cancer (GC) remains to be clarified.

METHODS

To explore the function of miR-4490 in GC, we performed colony formation, EdU incorporation, qRT-PCR, Western blotting, in situ hybridization (ISH), immunohistochemistry (IHC), flow cytometry, ChIP and dual-luciferase reporter assays. In addition, the growth, migration and invasion capacities of GC cells were evaluated.

RESULTS

We found that miR-4490 was significantly downregulated in primary GC samples and in GC-derived cell lines compared with normal controls, and that this expression level was negatively correlated with GC malignancy. Exogenous miR-4490 expression not only reduced cell cycle progression and proliferation, but also significantly inhibited GC cell migration, invasion and epithelial-mesenchymal transition (EMT) in vitro. Mechanistically, we found that miR-4490 directly targets USP22, which mediates inhibition of GC cell proliferation and EMT-induced metastasis in vitro and in vivo. Moreover, we found through luciferase and ChIP assays that transcription factor POU2F1 can directly bind to POU2F1 binding sites within the miR-4490 and USP22 promoters and, by doing so, modulate their transcription. Spearman's correlation analysis revealed a positive correlation between USP22 and POU2F1 expression and negative correlations between miR-4490 and USP22 as well as miR-4490 and POU2F1 expression in primary GC tissues.

CONCLUSION

Based on our results we conclude that miR-4490 acts as a tumor suppressor, and that the POU2F1/miR-4490/USP22 axis plays an important role in the regulation of growth, invasion and EMT of GC cells.

The role of DUBs in the post-translational control of cell migration

Cell migration is a multifactorial/multistep process that requires the concerted action of growth and transcriptional factors, motor proteins, extracellular matrix remodeling and proteases. In this review, we focus on the role of transcription factors modulating Epithelial-to-Mesenchymal Transition (EMT-TFs), a fundamental process supporting both physiological and pathological cell migration. These EMT-TFs (Snail1/2, Twist1/2 and Zeb1/2) are labile proteins which should be stabilized to initiate EMT and provide full migratory and invasive properties. We present here a family of enzymes, the deubiquitinases (DUBs) which have a crucial role in counteracting polyubiquitination and proteasomal degradation of EMT-TFs after their induction by TGFβ, inflammatory cytokines and hypoxia. We also describe the DUBs promoting the stabilization of Smads, TGFβ receptors and other key proteins involved in transduction pathways controlling EMT.

Clinical, pathological and prognostic implications of USP22, SIRT1 and E-cadherin expression in papillary thyroid cancer (PTC) and adjacent non-neoplastic tissue

Introduction

Ubiquitin-specific peptidase 22 (USP22) is described as a stem cell (CSC) marker which is involved in many biological processes, including cancer development, cellular growth and differentiation. Sirtuin 1 (SIRT1) controls a set of biologic processes that range from metabolic homeostasis to cancer. E-cadherin is a calcium-dependent intercellular adhesion molecule. Clinically, USP22, SIRT1 and E-cadherin have been studied to predict prognosis of a variety of cancers but the detailed roles of their expression in papillary thyroid cancer (PTC) and their relation to cancer invasion, metastases and recurrence are still not fully explained.

Aim of the study

To evaluate the expression of USP22, SIRT1 & E-cadherin in PTC tissues and adjacent non-neoplastic thyroid tissue and to correlate their expression with histopathology, clinical, pathological and prognostic parameters of PTC patients.

Methods

We have assessed USP22, SIRT1 & E-cadherin expression using immunohistochemistry in 40 cases with PTC in both malignant tissue and adjacent non-neoplastic tissue, analyzed the relationships between their levels of expression, clinic-pathological parameters, prognosis and survival of patients.

Results

High protein expression levels of both USP22, SIRT1 in addition to low E-cadherin expression in PTC were associated with larger tumors, extra-thyroidal extension, vascular invasion, lymphatic spread (p < 0.001), existence of distant metastases (p = 0.005 & 0.012 respectively), higher stage of the disease (p = 0.012 & 0.042 respectively) and worse five-years overall survival rates (p < 0.001).

Conclusion

Patients having advanced PTC with unfavorable prognosis had high levels of both USP22, SIRT1 in addition to low E-cadherin expression.

High expression of ubiquitin carboxyl-terminal hydrolase 22 is associated with poor prognosis in hepatitis B virus-associated liver cancer

Deubiquitinating enzymes regulate protein activity and cell homeostasis by removing ubiquitin moieties from various substrates. Ubiquitin carboxyl-terminal hydrolase 22 (USP22) is a member of the deubiquitinating protease family and is associated with the development of several tumor types. A previous study demonstrated that USP22 is highly expressed in liver cancer, and its high expression is associated with resistance to chemotherapy. However, the role of USP22 in hepatitis B virus (HBV)-associated liver cancer has not yet been elucidated. The current study demonstrated that USP22 was highly expressed in the tissues of patients with HBV-associated liver cancer, and its high expression was associated with clinicopathological characteristics, including tumor size, clinical stage and prognosis. Further results indicated that USP22 may regulate the proliferative and apoptotic abilities of HepG2.2.15 cells. Additionally, investigation into the underlying mechanism, using small interfering RNA, revealed that the downregulation of USP22 inhibited proliferation and promoted apoptosis though the phosphoinositide 3-kinase/protein kinase B signaling pathway. Therefore, USP22 has the potential to be used as an independent predictor of patient prognosis, as well as a therapeutic target for the treatment of HBV-associated liver cancer.

Pirarubicin reduces USP22 expression by inhibiting CREB-1 phosphorylation in HeLa cells

The expression of ubiquitin specific peptidase 22 (USP22) is upregulated in several types of cancer, and has been implicated in tumorigenesis. Pirarubicin (THP), an anthracycline antineoplastic drug, can induce apoptosis of several types of cancer cells. However, the molecular mechanisms underlying the action of THP remain to be elucidated. In the current study, treatment with THP induced HeLa cell apoptosis and decreased USP22 expression in a dose- and time-dependent manner. THP reduced the USP22 promoter-regulated luciferase activity, regardless of the mutation of transcriptional activator MYB or E3 ubiquitin-protein ligase SP1 binding sequences; however, this effect was abrogated by the mutation of cyclic AMP-responsive element-binding protein (CREB) binding sequence in HeLa cells. Furthermore, the inhibition on the USP22 promoter activity by THP was not affected by overexpression of CREB-1 in HeLa cells. Additionally, treatment with THP significantly decreased the phosphorylation of CREB-1 at ser133 in HeLa cells. Quantitative chromatin immunoprecipitation assay revealed that THP significantly inhibited the binding of CREB-1 to the USP22 promoter in HeLa cells. The present study demonstrated that THP decreased USP22 expression and promoted HeLa cell apoptosis partially by inhibiting the phosphorylation of CREB-1. The current results may provide novel insights into the molecular mechanisms underlying the pharmacological effect of THP on cancer cell apoptosis.

USP22 controls multiple signaling pathways that are essential for vasculature formation in the mouse placenta

USP22, a component of the SAGA complex, is overexpressed in highly aggressive cancers, but the normal functions of this deubiquitinase are not well defined. We determined that loss of USP22 in mice results in embryonic lethality due to defects in extra-embryonic placental tissues and failure to establish proper vascular interactions with the maternal circulatory system. These phenotypes arise from abnormal gene expression patterns that reflect defective kinase signaling, including TGFβ and several receptor tyrosine kinase pathways. USP22 deletion in endothelial cells and pericytes that are induced from embryonic stem cells also hinders these signaling cascades, with detrimental effects on cell survival and differentiation as well as on the ability to form vessels. Our findings provide new insights into the functions of USP22 during development that may offer clues to its role in disease states.

TGFβ-Activated USP27X Deubiquitinase Regulates Cell Migration and Chemoresistance via Stabilization of Snail1

In cancer cells, epithelial-to-mesenchymal transition (EMT) is controlled by Snail1, a transcriptional factor also required for the activation of cancer-associated fibroblasts (CAF). Snail1 is short-lived in normal epithelial cells as a consequence of its coordinated and continuous ubiquitination by several F-box-specific E3 ligases, but its degradation is prevented in cancer cells and in activated fibroblasts. Here, we performed an siRNA screen and identified USP27X as a deubiquitinase that increases Snail1 stability. Expression of USP27X in breast and pancreatic cancer cell lines and tumors positively correlated with Snail1 expression levels. Accordingly, downregulation of USP27X decreased Snail1 protein in several tumor cell lines. USP27X depletion impaired Snail1-dependent cell migration and invasion and metastasis formation and increased cellular sensitivity to cisplatin. USP27X was upregulated by TGFβ during EMT and was required for TGFβ-induced expression of Snail1 and other mesenchymal markers in epithelial cells and CAF. In agreement with this, depletion of USP27X prevented TGFβ-induced EMT and fibroblast activation. Collectively, these results indicate that USP27X is an essential protein controlling Snail1 expression and function and may serve as a target for inhibition of Snail1-dependent tumoral invasion and chemoresistance. SIGNIFICANCE: These findings show that inhibition of USP27X destabilizes Snail1 to impair EMT and renders tumor cells sensitive to chemotherapy, thus opening new strategies for the inhibition of Snail1 expression and its protumoral actions.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/1/33/F1.large.jpg.

Control of CCND1 ubiquitylation by the catalytic SAGA subunit USP22 is essential for cell cycle progression through G1 in cancer cells

Overexpression of the deubiquitylase ubiquitin-specific peptidase 22 (USP22) is a marker of aggressive cancer phenotypes like metastasis, therapy resistance, and poor survival. Functionally, this overexpression of USP22 actively contributes to tumorigenesis, as USP22 depletion blocks cancer cell cycle progression in vitro, and inhibits tumor progression in animal models of lung, breast, bladder, ovarian, and liver cancer, among others. Current models suggest that USP22 mediates these biological effects via its role in epigenetic regulation as a subunit of the Spt-Ada-Gcn5-acetyltransferase (SAGA) transcriptional cofactor complex. Challenging the dogma, we report here a nontranscriptional role for USP22 via a direct effect on the core cell cycle machinery: that is, the deubiquitylation of the G1 cyclin D1 (CCND1). Deubiquitylation by USP22 protects CCND1 from proteasome-mediated degradation and occurs separately from the canonical phosphorylation/ubiquitylation mechanism previously shown to regulate CCND1 stability. We demonstrate that control of CCND1 is a key mechanism by which USP22 mediates its known role in cell cycle progression. Finally, USP22 and CCND1 levels correlate in patient lung and colorectal cancer samples and our preclinical studies indicate that targeting USP22 in combination with CDK inhibitors may offer an approach for treating cancer patients whose tumors exhibit elevated CCND1.

Ubiquitin-Proteasome Axis, Especially Ubiquitin-Specific Protease-17 (USP17) Gene Family, is a Potential Target for Epithelial-Mesenchymal Transition in High-Grade Serous Ovarian Cancer

OBJECTIVES

To investigate gene expression differences and related functions between primary tumor, malignant cells in ascites, and metastatic peritoneal implant in high-grade serous ovarian cancer.

METHODS

Biopsies from primary tumor, peritoneal implant, and ascites were collected from 10 patients operated primarily for high-grade, advanced-staged serous ovarian cancer. Total RNA isolation was performed from collected tissue biopsy and fluid samples, and RNA expression profile was measured. Messenger RNA expression profiles of 3 different groups were compared. Functional analyses of candidate genes were carried out by gene ontology and pathway analysis.

RESULTS

There were significant differences in the expression of 5 genes between primary tumor and peritoneal implant, 979 genes between primary tumor and malignant cells in ascites, and 649 genes between peritoneal implant and malignant cells in ascites. Three commonly enriched gene ontology functions between "primary tumor and malignant cells in the ascites" and "peritoneal implant and malignant cells in the ascites" were protein deubiquitination, ubiquitin-dependent protein catabolism, and apoptotic processes. All genes related to these functions belonged to USP17 gene family.

CONCLUSION

Gene expression difference between primary tumor and the peritoneal implant is not as much as the difference between primary tumor and free cells in the ascites. These results show that malignant cells in the ascites return into its genetic origin after they invade on the peritoneum. Significantly increased expression of DUB-enzyme genes, SNAR gene family, and ribosomal pathway genes in epithelial-mesenchymal transition suggests that this regulation is ubiquitin-proteasome dependent. Especially, this is the first study that offers USP17 as a potential target for epithelial-mesenchymal transition.

USP22 promotes resistance to EGFR-TKIs by preventing ubiquitination-mediated EGFR degradation in EGFR-mutant lung adenocarcinoma

As a newly discovered deubiquitinating enzyme, ubiquitin-specific protease 22 (USP22) is predictive of therapeutic outcomes in individual cancer patients. However, its clinical effects on malignancy and its roles in conferring resistance to EGFR-TKIs (epidermal growth factor receptor-tyrosine kinase inhibitors) in lung adenocarcinoma (ADC) remain largely unknown. Here, we showed that USP22 promotes cell proliferation, migration and invasion, and contributes to resistance to EGFR-TKIs in EGFR mutant lung ADC cells. Mechanistically, USP22 deubiquitinates EGFR localized on late endosomes, prevents ubiquitination mediated EGFR degradation and enhances recycling of EGFR after EGF stimulation. Additionally, USP22 sustained the activation of multiple EGFR downstream signaling pathways, including STAT3, AKT/mTOR and MEK/ERK pathways, in lung ADC cell lines H1975 and PC9. Furthermore, USP22 stabilizes EGFR protein expression, which correlates with USP22 expression in EGFR-mutant lung ADC patient samples. We are the first to demonstrate that silencing USP22 counteracts EGFR-TKIs resistance both in vitro and in vivo. We propose USP22 as a potential therapeutic target for EGFR-TKIs-resistant lung ADC.

High expression of USP22 predicts poor prognosis and advanced clinicopathological features in solid tumors: a meta-analysis

Introduction

The expression of USP22 has been demonstrated to play a pivotal role in solid tumors. However, the prognostic value of USP22 still remains unknown.

Materials and methods

A systematic meta-analysis was performed to assess the prognostic value of USP22 in cancers. A literature collection was conducted from inception to June 8, 2017 by searching PubMed, Cochrane Library, Embase, Ovid and Web of Science databases. The pooled hazard ratio (HR) and odds ratio (OR) were used to correlate high expression of USP22 with overall survival (OS) and clinicopathological features.

Results

The results, pooled by 19 studies with 2,876 cases, indicated that high expression of USP22 predicted poor OS (HR=2.48, 95% CI: 2.11–2.84, p<0.001) and disease-free survival (DFS; HR=2.55, 95% CI: 2.05–3.05, p<0.001) of cancer patients. Furthermore, high expression of USP22 was also significantly associated with advanced clinicopathological parameters, including tumor stage, tumor differentiation, metastasis, nodal status and tumor size.

Conclusion

Our finding revealed that USP22 might be an indicator of poor prognosis and advanced clinicopathological features of solid tumors and could be served as a novel biomarker.

USP22 drives colorectal cancer invasion and metastasis via epithelial-mesenchymal transition by activating AP4

Ubiquitin specific peptidase 22 (USP22), a putative cancer stem cell marker, is overexpressed in liver metastases of colorectal cancer (CRC). However, the mechanism by which USP22 promotes CRC metastasis remains largely unknown. Here, we report that USP22 and AP4 are simultaneously overexpressed during TGF-β1-induced CRC cell epithelial-mesenchymal transition (EMT). USP22 up-regulation enhances CRC cell migration and invasion and EMT-related marker and AP4 expression, but these effects are partly blocked by AP4 knockdown. In addition, USP22 binds to the promoter region of AP4 to activate its transcription. In vivo, elevated USP22 expression promotes CRC cell metastasis to the lungs in nude mice, as evidenced by the fact that CRC metastatic nodules stain deeply positive for USP22 and AP4. In human CRC tissues, the genes encoding USP22 and AP4 are overexpressed in metastatic liver lesions compared with primary cancer tissues, and their overexpression is significantly associated with poor CRC patient survival. These findings indicate that USP22 and AP4 may serve as prognostic markers for predicting the risk of developing distant metastases in CRC.

USP14 is a predictor of recurrence in endometrial cancer and a molecular target for endometrial cancer treatment

Endometrial adenocarcinoma is the most common gynecologic malignancy in the United States. Most endometrial cancer cases are diagnosed at an early stage and have good prognosis. Unfortunately a subset of patients with early stage and low grade disease experience recurrence for reasons that remain unclear. Recurrence is often accompanied by chemoresistance and high mortality.

Deubiquitinating enzymes (DUBs) are key components of the ubiquitin-dependent protein degradation pathway and act as master regulators in a number of metabolic processes including cell growth, differentiation, and apoptosis. DUBs have been shown to be upregulated in a number of human cancers and their aberrant activity has been linked to cancer progression, initiation and onset of chemoresistance. Thus, selective inhibition of DUBs has been proposed as a targeted therapy for cancer treatment.

This study suggests the DUB USP14 as a promising biomarker for stratifying endometrial cancer patients at diagnosis based on their risk of recurrence. Further USP14 is expressed along with the marker of proliferation Ki67 in endometrial cancer cells in situ. Lastly, pharmacological targeting of USP14 with the FDA approved small-molecule inhibitor VLX1570, decreases cell viability in chemotherapy resistant endometrial cancer cells with a mechanism consistent with cell cycle arrest and caspase-3 mediated apoptosis.

Prognostic and clinicopathological significance of ubiquitin-specific protease 22 overexpression in cancers: evidence from a meta-analysis

Purpose

This meta-analysis study aimed to reveal the prognostic relevance of ubiquitin-specific protease 22 (USP22) expression in patients with cancers.

Methods

PubMed, Embase, and the Cochrane Library electronic databases were searched for relevant studies published up to April 2017. The prognostic value of USP22 expression was evaluated by hazard ratio with 95% confidence intervals (CIs). Relative risk (RR) with 95% CIs assessed the effects of USP22 expression on clinicopathological parameters. A total of 16 studies of 2,233 Chinese patients were included in the final meta-analysis.

Results

A significant association was found between USP22 overexpression and survival in patients with cancers. The pooled RR indicated that USP22 overexpression was related to histological grade, advanced tumor–node–metastasis stage, positive lymph node metastasis, and distant metastasis.

Conclusion

This meta-analysis demonstrated that USP22 could be a novel biomarker for predicting prognosis in patients with cancers in the Chinese population.

MicroRNA-30e-5p suppresses non-small cell lung cancer tumorigenesis by regulating USP22-mediated Sirt1/JAK/STAT3 signaling

MicroRNA-30e-5p (miR-30e-5p) is a tumor suppressor that is known to be downregulated in non-small cell lung cancer (NSCLC). However, how miR-30e-5p inhibits NSCLC tumorigenesis is not known. Ubiquitin-specific peptidase 22 (USP22) is upregulated in NSCLC and promotes tumorigenesis via a Sirt1-JAK-STAT3 pathway. In this study, we investigated whether miR-30e-5p inhibits tumor growth by targeting USP22 in NSCLC. Our results reveal that miR-30e-5p expression was correlated negatively with USP22 in NSCLC tissues. Luciferase reporter assays showed that miR-30e-5p negatively regulated USP22 expression by binding to a specific sequence in the 3'UTR. MiR-30e-5p overexpression and USP22 knockdown significantly inhibited tumor growth in vivo and induced cell cycle arrest and apoptosis in NSCLC cells in vitro. The effects of miR-30e-5p inhibition were prevented by USP22 knockdown. MiR-30e-5p inhibited SIRT1 expression and increased expression of p53 and the phosphorylated form of STAT3 (pSTAT3). Furthermore, miR-30e-5p prevented USP22-mediated regulation of SIRT1, pSTAT3, and p53 expression. Taken together, these findings suggest that miR-30e-5p suppresses NSCLC tumorigenesis by downregulatingUSP22-mediated Sirt1/JAK/STAT3 signaling. Our study has identified miR-30e-5p as a potential therapeutic target for the treatment of NSCLC.

Emerging role of DUBs in tumor metastasis and apoptosis: Therapeutic implication

Malfunction of ubiquitin-proteasome system is tightly linked to tumor formation and tumor metastasis. Targeting the ubiquitin-pathway provides a new strategy for anti-cancer therapy. Despite the parts played by ubiquitin modifiers, removal of ubiquitin from the functional proteins by the deubiquitinating enzymes (DUBs) plays an important role in governing the multiple steps of the metastatic cascade, including local invasion, dissemination, and eventual colonization of the tumor to distant organs. Both deregulated ubiquitination and deubiquitination could lead to dysregulation of various critical events and pathways such as apoptosis and epithelial-mesenchymal transition (EMT). Recent TCGA study has further revealed the connection between mutations of DUBs and various types of tumors. In addition, emerging drug design targeting DUBs provides a new strategy for anti-cancer therapy. In this review, we will summarize the role of deubiquitination and highlight the recent discoveries of DUBs with regards to multiple metastatic events including anti-apoptosis pathway and EMT. We will further discuss the regulation of deubiquitination as a novel strategy for anti-cancer therapy.

let-7b and let-7c microRNAs promote histone H2B ubiquitylation and inhibit cell migration by targeting multiple components of the H2B deubiquitylation machinery

Monoubiquitylation of histone H2B (H2Bub1) is catalyzed mainly by the RNF20/RNF40 complex and erased by multiple deubiquitylating enzymes (DUBs). H2Bub1 influences many aspects of chromatin function, including transcription regulation and DNA repair. Cancer cells often display reduced levels of H2Bub1, and this reduction may contribute to cancer progression. The let-7 family of microRNAs comprises multiple members with reported tumor suppressive features, whose expression is frequently downregulated in cancer. We now report that let-7b and let-7c can positively regulate cellular H2Bub1 levels. Overexpression of let-7b and let-7c in a variety of non-transformed and cancer-derived cell lines results in H2Bub1 elevation. The positive effect of let-7b and let-7c on H2Bub1 levels is achieved through targeting of multiple mRNAs, coding for distinct components of the H2B deubiquitylation machinery. Specifically, let-7b and let-7c bind directly and inhibit the mRNAs encoding the DUBs USP42 and USP44, and also the mRNA encoding the adapter protein ATXN7L3, which is part of the DUB module of the SAGA complex. RNF20 knockdown strongly reduces H2Bub1 levels and increases the migration of non-transformed mammary epithelial cells and breast cancer-derived cells. Remarkably, overexpression of let-7b, which partly counteracts the effect of RNF20 knockdown on H2Bub1 levels, also reverses the pro-migratory effect of RNF20 knockdown. Likewise, ATXN7L3 knockdown also increases H2Bub1 levels and reduces cell migration, and this anti-migratory effect is abolished by simultaneous knockdown of RNF20. Together, our findings uncover a novel function of let-7 microRNAs as regulators of H2B ubiquitylation, suggesting an additional mechanism whereby these microRNAs can exert their tumor suppressive effects.

Expression of MYSM1 is associated with tumor progression in colorectal cancer

Colorectal cancer, the third most common cancer in both men and women, has gradually increased in recent years. MYSM1has been investigated as a regulator of hematopoiesis and lymphocyte development in human. It has been reported that some tumor-related genes were modulated by MYSM1. However, its exact role in cancer development remains unclear. Herein, we aimed to examine the expression level of MYSM1 in tumor tissues and its correlation with clinicopathology and survivals of patients with colorectal cancer (CRC).MYSM1expressions in tumor specimens resected from 123 CRC patients were detected by immunochemistry and Western blot analysis. The results showed that MYSM1 was significantly highly expressed in carcinoma tissues compared with adjacent normal mucosa tissues (P<0.05). Correlation analyses by Pearson's chi-square test demonstrated that MYSM1 in tumors was positively correlated with tumor status (pathological assessment of the primary tumor (pT, P<0.001), regional lymph nodes (pN, P = 0.013), distant metastasis (pM, P<0.001)) and clinic stage (P<0.001); Whereas, MYSM1 was not associated with tumor size of CRC patients and was positively associated with tumor differentiation grade (P = 0.015). Patients with positiveMYSM1expression showed poor survival compared with the MYSM1 negative group (P<0.001).Simultaneously, multivariate Cox regression analysis indicated thatMYSM1 expression in tumor cells was an independent factor for reduced overall survival in CRC patients (P<0.001).Additionally,MYSM1 in CRC SW480 cells was silenced by small interference RNA (siRNA) technology. Scratch assay and Transwell assay showed that MYSM1 silencing decreased migration and invasion abilities of SW480 cells. These data suggested that expression of MYSM1 was associated with the progression of CRC and might be a potential biomarker for clinical prognosis.

Long Noncoding RNA-LET Suppresses Tumor Growth and EMT in Lung Adenocarcinoma

Recently, many studies showed that long noncoding RNAs (lncRNAs) are involved in tumor progression. It is reported that lncRNA-LET is downregulated and has antitumor effect on several types of cancer. This study focuses on the role of lncRNA-LET on lung adenocarcinoma (LAC) progression. RT-PCR results indicated that frequent downregulation of lncRNA-LET in LAC tissues was related to clinicopathologic factors. lncRNA-LET knockdown significantly promoted LAC cell proliferation, invasion, and migration while lncRNA-LET overexpression obviously inhibited LAC cell proliferation, invasion, and migration, indicating a tumor inhibition of lncRNA-LET in LAC progression. Besides, lncRNA-LET inhibited EMT and negatively regulated Wnt/β-catenin pathway in part. Our study suggests that lncRNA-LET exhibits an important tumor-suppressive effect on LAC progression by inhibiting EMT and Wnt/β-catenin pathway, which provides potential therapeutic targets for LAC.

MDMX (MDM4), a Promising Target for p53 Reactivation Therapy and Beyond

The MDMX protein was identified as a p53-interacting protein with a strong similarity to MDM2. Like Mdm2, Mdmx expression is essential for curbing p53 activity during embryonic development, indicating nonredundant functions of Mdmx and Mdm2. There is now a large body of evidence indicating that cancers frequently up-regulate MDMX expression as a means to dampen p53 tumor-suppressor function. Importantly, MDMX also shows p53-independent oncogenic functions. These data make MDMX an attractive therapeutic target for cancer therapy. Here, we summarize the mechanisms used by cancer cells to increase MDMX expression and promising pharmacological strategies to target MDMX in cancer-in particular, the recent findings that antisense oligonucleotides (ASOs) can be used to efficiently modulate MDMX messenger RNA (mRNA) splicing.

IRE-1α regulates expression of ubiquitin specific peptidases during hypoxic response in U87 glioma cells

IRE-1α (inositol requiring enzyme-1α), the most evolutionarily conserved of the endoplasmic reticulum stress signaling pathways, is highly implicated in sustaining the proliferation of glioma cells and subsequent tumor growth, which is decreased by the inhibition of IRE-1α. To explore the IRE-1α mediated regulation of ubiquitin system in glioma cells, the expression of a subset of ubiquitin specific peptidases (USP) and of ubiquitin activating enzyme E1-like protein/autophagy related 7 (GSA7/ATG7) genes was studied, during hypoxic stress in wild type and U87 glioma cells with inhibited IRE-1α. Hypoxic treatment of wild type glioma cells leads to the up-regulation of USP25 and the concomitant downregulation of USP1, USP10, USP14, and GSA7 genes. USP4 and USP22 genes expression did not significantly change with hypoxic treatment. Inhibition of IRE-1α activity led to up-regulation of USP1, USP4, USP10, USP22, and USP25, while USP14 and GSA7 genes were down-regulated. Therefore, IRE-1α activity modifies substrate-targeting specificity to proteasome during hypoxic stress, which in turn can affect cell survival. Inhibition of IRE-1α correlates directly with deregulation of ubiquitin specific peptidases and GSA7 in a fashion that ultimately slows tumor growth.

S100A4 participates in epithelial-mesenchymal transition in breast cancer via targeting MMP2

Numerous studies have shown that S100A4 acquires its metastasis-promoting effects via inducing epithelial-mesenchymal transition (EMT). However, its role and mechanism in EMT in breast cancer had not been clearly elucidated. Herein, we showed that the knockdown of S100A4 expression in breast cancer cell lines, MDA-MB-231 and MDA-MB-468, inhibited not only cell invasion ability greatly, but also the occurrence of EMT significantly. In addition, S100A4 knockdown could also decrease the expression of MMP2, a promoter and a mediator of the EMT processes in cancer. Above all, restoring the expression of MMP2 in MDA-MB-231 and MDA-MB-468 could not only rescue the invasion ability inhibited by knockdown of S100A4, but also reverse the EMT suppressed by knockdown of S100A4. In summary, our results indicated that S100A4 could promote the invasion ability of breast cancer cells via EMT, more importantly, it could participate in EMT via regulating MMP2 in breast cancer. Therefore, S100A4 could be a candidate biomarker for defining breast cancer metastasis and useful target for therapy.