Ubiquitin-specific Peptidase 22 Expression Research Articles

EZH2 Inhibition Enhances PD-L1 Protein Stability Through USP22-Mediated Deubiquitination in Colorectal Cancer.

The regulation of PD-L1 is the key question, which largely determines the outcome of the immune checkpoint inhibitors (ICIs) based therapy. However, besides the transcription level, the protein stability of PD-L1 is closely correlated with its function and has drawn increasing attention. In this study, EZH2 inhibition enhances PD-L1 expression and protein stability, and the deubiquitinase ubiquitin-specific peptidase 22 (USP22) is identified as a key mediator in this process. EZH2 inhibition transcriptionally upregulates USP22 expression, and upregulated USP22 further stabilizes PD-L1. Importantly, a combination of EZH2 inhibitors with anti-PD-1 immune checkpoint blockade therapy improves the tumor microenvironment, enhances sensitivity to immunotherapy, and exerts synergistic anticancer effects. In addition, knocking down USP22 can potentially enhance the therapeutic efficacy of EZH2 inhibitors on colon cancer. These findings unveil the novel role of EZH2 inhibitors in tumor immune evasion by upregulating PD-L1, and this drawback can be compensated by combining ICI immunotherapy. Therefore, these findings provide valuable insights into the EZH2-USP22-PD-L1 regulatory axis, shedding light on the optimization of combining both immune checkpoint blockade and EZH2 inhibitor-based epigenetic therapies to achieve more efficacies and accuracy in cancer treatment.

USP22 overexpression fails to augment tumor formation in MMTV-ERBB2 mice but loss of function impacts MMTV promoter activity.

The Ubiquitin Specific Peptidase 22 (USP22), a component of the Spt-Ada-Gcn5 Acetyltransferase (SAGA) histone modifying complex, is overexpressed in multiple human cancers, but how USP22 impacts tumorigenesis is not clear. We reported previously that Usp22 loss in mice impacts execution of several signaling pathways driven by growth factor receptors such as erythroblastic oncogene B b2 (ERBB2). To determine whether changes in USP22 expression affects ERBB2-driven tumorigenesis, we introduced conditional overexpression or deletion alleles of Usp22 into mice bearing the Mouse mammary tumor virus-Neu-Ires-Cre (MMTV-NIC) transgene, which drives both rat ERBB2/NEU expression and Cre recombinase activity from the MMTV promoter resulting in mammary tumor formation. We found that USP22 overexpression in mammary glands did not further enhance primary tumorigenesis in MMTV-NIC female mice, but increased lung metastases were observed. However, deletion of Usp22 significantly decreased tumor burden and increased survival of MMTV-NIC mice. These effects were associated with markedly decreased levels of both Erbb2 mRNA and protein, indicating Usp22 loss impacts MMTV promoter activity. Usp22 loss had no impact on ERBB2 expression in other settings, including MCF10A cells bearing a Cytomegalovirus (CMV)-driven ERBB2 transgene or in human epidermal growth factor receptor 2 (HER2)+ human SKBR3 and HCC1953 cells. Decreased activity of the MMTV promoter in MMTV-NIC mice correlated with decreased expression of known regulatory factors, including the glucocorticoid receptor (GR), the progesterone receptor (PR), and the chromatin remodeling factor Brahma-related gene-1 (BRG1). Together our findings indicate that increased expression of USP22 does not augment the activity of an activated ERBB2/NEU transgene but impacts of Usp22 loss on tumorigenesis cannot be assessed in this model due to unexpected effects on MMTV-driven Erbb2/Neu expression.

USP22 promotes aspirin-induced trophoblast cell proliferation as well as migration via Wnt/β-catenin pathway in preeclampsia

Purpose: To investigate the involvement of ubiquitin-specific peptidase 22 (USP22) in the pathogenesis of preeclampsia (PE), and the potential mechanism of action.
 Methods: To investigate the role of USP22 in preeclampsia, immunoblot assay as well as quantitative real-time polymerase chain reaction (qRT-PCR) were conducted to determine USP22 expression levels in placental tissues from both the control (non-preeclampsia normal) and the PE cases. Furthermore, cell counting kit-8 as well as EdU assays were performed to assess the impact of USP22 on the viability of HTR-8/Svneo and TEV-1 cells. Furthermore, wound closure and Transwell assays were used to examine the effect of USP22 on cell motility, while tube formation assay was used to determine the effect of USP22 on the angiogenesis of trophoblast cells. Finally, the effect of USP22 on Wnt/β-catenin pathway in HTR-8/Svneo and TEV-1 human trophoblast cells was evaluated by immunoblot analysis.
 Results: USP22 expression was significantly reduced in PE placental tissue compared to control tissues. In addition, USP22 promoted trophoblast cell proliferation, increased cell motility as well as enhanced angiogenesis capacity. USP22 regulated the proliferation as well as migration of trophoblast cells via Wnt/β-catenin pathway. Notably, USP22 enhanced cell proliferation and migration in aspirininduced PE.
 Conclusion: USP22 plays a crucial role in inhibiting trophoblast cell growth by regulating Wnt/β-catenin pathway. Therefore, targeting USP22 may hold promise for the treatment of PE.

LncRNA MALAT1 Regulates USP22 Expression Through EZH2-Mediated H3K27me3 Modification to Accentuate Sepsis-Induced Myocardial Dysfunction

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a long non-coding RNA (lncRNA), has been confirmed to recruit enhancer of zeste 2 polycomb repressive complex 2 subunit (EZH2) to regulate cardiomyocyte apoptosis in diabetic cardiomyopathy. However, whether the similar regulatory axis exists in sepsis-induced myocardial dysfunction (SIMD) has not been clearly established. The current study sought to define the mechanism governing MALAT1-mediated EZH2 in SIMD. MALAT1 was significantly upregulated in lipopolysaccharide-induced cardiomyocytes. Depletion of MALAT1 by caudal vein injection of small interfering RNA targeting MALAT1 alleviated myocardial injury in SIMD rats, restored cardiac function, reduced oxidative stress production and fibrosis, and inhibited inflammatory factors and apoptosis in myocardial tissues. Moreover, MALAT1 bound to EZH2 and promoted EZH2 activity in the nucleus of cardiomyocytes. EZH2 repressed ubiquitin-specific peptidase 22 (USP22) expression through H3K27me3 modification. EZH2 elevation aggravated the cardiac injury in SIMD rats, while USP22 upregulation inhibited the effect of EZH2, which reduced the cardiac injury in SIMD rats. Taken together, MALAT1 decreased USP22 expression by interacting with EZH2, thereby worsening SIMD, highlighting an attractive therapeutic strategy for SIMD.

Down-regulation of USP22 reduces cell stemness and enhances the sensitivity of pancreatic cancer cells to cisplatin by inactivating the Wnt/β-catenin pathway

ObjectivePancreatic cancer (PC) has the worst prognosis of all common cancers worldwide. This study was intended to investigate the role of ubiquitin specific peptidase 22 (USP22) in cisplatin sensitivity of PC cells and its regulatory mechanism. MethodsThe expression of USP22 and the toxicity of cisplatin to PC cells were detected. The two cell lines AsPC-1 and CAPAN-1 with the most differential drug resistance were selected. By down-expressing USP22 in CAPAN-1 cells and over-expressing USP22 in AsPC-1 cells, the survival rate of PC cells treated with cisplatin was detected. The mRNA expressions of stem cell markers, cell stemness, migration ability and apoptosis of PC cells were detected. The expression of Wnt/β-catenin pathway related proteins was detected. The role of the Wnt/β-catenin pathway in PC cell stemness and cisplatin sensitivity was explored after adding the inhibitor HLY78 and activator DKK1. ResultsUSP22 was highly-expressed in PC cells, and the sensitivity of PC cells to cisplatin was negatively-correlated with USP22 expression. Downregulation of USP22 raised the sensitivity of PC cells to cisplatin, reduced the levels of stem cell markers, reduced the tumor sphere formation and migration, and promoted apoptosis. Silencing USP22 inhibited the Wnt/β-catenin pathway. Inhibition of USP22 reduced the cell stemness and augmented the sensitivity of PC cells to cisplatin by inhibiting the Wnt/β-catenin pathway. ConclusionSilencing USP22 can inhibit the Wnt/β-catenin pathway to reduce cell stemness and enhance the sensitivity of PC cells to cisplatin.

USP22 controls necroptosis by regulating receptor-interacting protein kinase 3 ubiquitination.

Dynamic control of ubiquitination by deubiquitinating enzymes is essential for almost all biological processes. Ubiquitin‐specific peptidase 22 (USP22) is part of the SAGA complex and catalyzes the removal of mono‐ubiquitination from histones H2A and H2B, thereby regulating gene transcription. However, novel roles for USP22 have emerged recently, such as tumor development and cell death. Apart from apoptosis, the relevance of USP22 in other programmed cell death pathways still remains unclear. Here, we describe a novel role for USP22 in controlling necroptotic cell death in human tumor cell lines. Loss of USP22 expression significantly delays TNFα/Smac mimetic/zVAD.fmk (TBZ)‐induced necroptosis, without affecting TNFα‐mediated NF‐κB activation or extrinsic apoptosis. Ubiquitin remnant profiling identified receptor‐interacting protein kinase 3 (RIPK3) lysines 42, 351, and 518 as novel, USP22‐regulated ubiquitination sites during necroptosis. Importantly, mutation of RIPK3 K518 reduced necroptosis‐associated RIPK3 ubiquitination and amplified necrosome formation and necroptotic cell death. In conclusion, we identify a novel role of USP22 in necroptosis and further elucidate the relevance of RIPK3 ubiquitination as crucial regulator of necroptotic cell death.

Abstract PO-069: Characterizing cell-to-cell heterogeneity and chromosome instability induced by USP22 deficiency in colorectal cancer

Abstract Chromosome instability (CIN) is an aberrant phenotype characterized by an increased rate of gains and losses of chromosomes. CIN is observed in most cancer types, including 85% of colorectal cancer (CRC) cases. Although CIN is a driver of tumor heterogeneity and associated with drug resistance and poor patient prognosis, the genetic defects underlying CIN remain poorly understood. Ubiquitin Specific Peptidase 22 (USP22) is a deubiquitinating enzyme that targets mono-ubiquitin on lysine 120 of histone H2B (H2Bub1). H2Bub1 is a dynamic post-translational modification that modulates chromatin compaction. Importantly, homozygous or heterozygous USP22 deletion is observed in 45% of CRC cases, suggesting this may be a pathogenic event promoting CRC progression. Accordingly, we sought to characterize the impact reduced USP22 expression has on CIN. To reduce USP22 expression in karyotypically stable CRC (HCT116) and immortalized fibroblast (hTERT) cell lines, we employed transient siRNA silencing and stable CRISPR-Cas9 knockout (KO) models. Single-cell quantitative image-based analyses were utilized to monitor CIN-associated phenotypes, including changes in nuclear areas, micronucleus formation and chromosome numbers. In HCT116, USP22 silencing induced CIN phenotypes and an increase in H2Bub1 abundance in mitotic chromosomes. Subsequent mechanistic studies determined that this is accompanied by an increase in the recruitment of the spindle assembly checkpoint kinase BUB1 at metaphase centromeres and an increased frequency of lagging chromosomes in anaphase. Collectively, these data suggest that reduced USP22 expression alters H2Bub1 regulation in mitosis, which impairs mitotic fidelity, thereby inducing CIN. In addition, to assess the relevance of reduced USP22 expression in a distinct cellular context, the impact of USP22 silencing was assessed in hTERT, revealing similar CIN phenotypes, including changes in nuclear area and chromosome numbers. To assess the long-term impact USP22 deletions have on CIN, novel homozygous and heterozygous USP22-KO HCT116 clones were generated and monitored for three months, which revealed dynamic CIN phenotypes and ongoing changes in chromosome complements relative to controls. Collectively, these data identify USP22 as a novel CIN gene and indicate that USP22 deletions in cancer may drive intra-tumor genetic heterogeneity and thereby promote oncogenesis. Citation Format: Lucile M. Jeusset, Zelda D. Lichtensztejn, Kirk J. McManus. Characterizing cell-to-cell heterogeneity and chromosome instability induced by USP22 deficiency in colorectal cancer [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-069.

Long Non-Coding RNA SNHG16 Activates USP22 Expression to Promote Colorectal Cancer Progression by Sponging miR-132-3p.

BackgroundColorectal cancer (CRC) is the most common cause of cancer-related mortality in the world. Long non-coding RNAs (lncRNAs) are involved in the development of many cancers. However, studies on the effect of lncRNA small nucleolar RNA host gene 16 (SNHG16) on the proliferation, metastasis and apoptosis of CRC are still few.MethodsQuantitative real-time polymerase chain reaction (qRT-PCR) was performed to determine the expression levels of SNHG16, microRNA-132-3p (miR-132-3p) and ubiquitin specific peptidase 22 (USP22). The proliferation, apoptosis, migration and invasion of CRC cells were evaluated by the 3-(4,5-dimethyl-2 thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, flow cytometry and transwell assay, respectively. Dual-luciferase reporter assay was used to verify the interactions among SNHG16, miR-132-3p and USP22. Also, Western blot analysis was used to assess the protein levels of USP22 and metastasis-related markers. Moreover, mice xenograft models were used to determine the effect of SNHG16 on CRC tumor growth in vivo.ResultsSNHG16 was highly expressed in CRC tissues and cells. Knockdown of SNHG16 reduced the proliferation, migration, invasion, and promoted the apoptosis of CRC cells. MiR-132-3p could interact with SNHG16, and its inhibitor recovered the suppression effect of silenced SNHG16 on CRC cell progression. Besides, USP22 was a target of miR-132-3p, and its overexpression restored the inhibition effect of miR-132-3p mimic on CRC cell progression. In addition, interference of SNHG16 reduced CRC tumor growth in vivo.ConclusionLncRNA SNHG16 might act as an oncogene in CRC. The discovery of the SNHG16/miR-132-3p/USP22 pathway provided new thinking for the treatment of CRC.

Abstract 1743: Evaluating the effect of USP22 depletion on chromosome instability in colorectal cancer

Abstract Chromosome instability (CIN) is an aberrant phenotype defined as an increase in the rate at which whole chromosomes or large chromosomal fragments are gained or lost, and is observed in virtually all cancer types. Although CIN is associated with aggressive tumors, multi-drug resistance and poor patient prognosis, the genetic defects underlying CIN remain poorly understood. Preliminary data from our laboratory suggest that diminished USP22 (Ubiquitin-Specific Peptidase 22) expression induces CIN. Importantly, USP22 deletions and reduced USP22 expression are frequently observed in multiple cancer types, including colorectal cancer, suggesting diminished USP22 expression/function may be a pathogenic event underlying oncogenesis. Therefore, the present study seeks to evaluate the impact diminished USP22 expression has on CIN by determining whether karyotypically stable colorectal cancer (HCT116) and immortalized fibroblast (hTERT) cell lines can be converted into karyotypically unstable lines following the reduction of USP22 expression. Diminished USP22 expression was achieved by siRNA-based silencing or CRISPR-Cas9-mediated gene knockout (KO) and quantitative image-based single-cell analyses were employed to monitor changes in surrogate markers for CIN, including nuclear areas and chromosome numbers. USP22 silencing induced significant changes in nuclear area as well as increased frequencies of chromosomes gains and losses, which suggest USP22 is a CIN gene. Next, to assess the long-term impact diminished USP22 expression has on CIN, two HCT116 USP22-KO clones were monitored for 10 weeks and revealed dynamic changes in nuclear areas and chromosome numbers over time relative to controls. Collectively, these data identify USP22 as a novel CIN gene and indicate that USP22 deletions in cancer may have long-term impact on CIN and may thereby promote oncogenesis. Further analysis is ongoing to investigate the mechanism through which USP22 depletion induces CIN, and in particular its effect on H2B monoubiquitination. Characterizing the effect diminished USP22 expression has on CIN is the first step towards the development of therapeutic strategies targeting USP22-deficient cancers. Citation Format: Lucile M. Jeusset, Kirk J. McManus. Evaluating the effect of USP22 depletion on chromosome instability in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1743.

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.

Is co-expression of USP22 and HSP90 more effective in predicting prognosis of gastric cancer?

The ubiquitin-specific peptidase 22 (USP22) belongs to the largest subfamily of deubiquitylases and recent studies indicate that overexpression of USP22 may promote gastric cancer progression and predict prognosis. But little is known about the interaction network of USP22 in gastric cancer. In this study, we applied bioinformatics methods and found that USP22 was correlated with the heat shock protein 90 (HSP90) which is now considered to be a biomarker to predict the prognosis of gastric cancer. Then the siRNA transfection and western blotting were used to testify the correlation of USP22 and HSP90 in gastric cancer cells. The immunohistochemistry staining of the microarrays was applied to confirm the correlation of USP22 and HSP90 expression in gastric cancer tissue and further analysis showed that co-expression of USP22 and HSP90 was related to lymph node metastasis and more effective in predicting the prognosis of gastric cancer. In summary, our data demonstrate that correlation exists between USP22 and HSP90 expressions in gastric cancer and co-expression of USP22 and HSP90 may be more effective in predicting prognosis of gastric cancer.

MiR-30e-5p inhibits proliferation and metastasis of nasopharyngeal carcinoma cells by target-ing USP22.

To investigate the effects of miR-30e-5p on the proliferation, invasion and migration of nasopharyngeal carcinoma (NPC) cells, as well as its underlying mechanism. We detected the expressions of miR-30e-5p in NPC tissues, adjacent normal tissues, NPC cells (5-8F cells) and control cells (293T cells) by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). The target gene of miR-30e-5p was predicted by online software and ubiquitin-specific peptidase 22 (USP22) was screened out. Luciferase reporter gene assay was performed after NPC cells were co-transfected miR-30e-5p mimics or miR-30e-5p inhibitor and mutant-type or wild-type USP22, respectively. Expressions of miR-30e-5p and USP22 in 5-8F cells were detected by qRT-PCR and Western blotting. The proliferation of 5-8F cells was measured by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay, and the invasion and migration abilities were detected by transwell assay. The activation of the epithelial-mesenchymal transition (EMT) was analyzed by detecting expressions of EMT-associated proteins (E-cadherin and Vimentin) in NPC cells. Expression level of miR-30e-5p was remarkably reduced, while USP22 expression was elevated in NPC tissues and cells compared with the controls. Molecular mechanism analysis con-firmed that miR-30e-5p could negatively regulate mRNA and protein levels of USP22 by binding to its specific sequence of 3'UTR. Subsequent experiments showed that USP22 knockdown resulting from up-regulation of miR-30e-5p could inhibit proliferation, invasion, migration, and EMT in 5-8F cells. MiR-30e-5p was lowly expressed in NPC by targeting USP22, suggesting that miR-30e-5p could be used as a potential therapeutic target for NPC.

Highlights of This Issue

Cancer-associated fibroblasts (CAFs) promote cancer growth and metastasis. However, mechanistic understanding by which cancer cells promote activation of healthy fibroblasts into CAFs remains elusive. In the current issue, Goulet and colleagues demonstrate that exosomes released by bladder cancer cells are internalized by healthy fibroblasts (HFs) to promote CAF differentiation through the activation of the TGFβ/SMAD signaling pathway. In fact, exosomal TGFβ, shown to be localized inside the vesicle, contributed 53 to 86% of the total TGFβ present in the bladder cancer cell conditioned medium. In conclusion, this study highlights that TGFβ-derived cancer exosomes are important molecular modulators of tumor microenvironment and CAF differentiation.PARP inhibitors (PARPi) are synthetically lethal in tumors carrying BRCA1/2 mutations and with deficiencies in homologous recombination (HR)-mediated DNA repair. However, BRCA mutations are rare; thus, most tumors are resistant to PARPi. Sizemore and colleagues demonstrate that ionizing radiation (IR) induces BRCA1 sequestration to the cytoplasm and DNA repair deficiency, and subsequent PARPi synthetic lethality in multiple tumor model systems. Importantly, p53 status was discovered to be a significant determining factor of tumor cell sensitization to PARPi following IR. These results have the potential to significantly increase the number of patients who may clinically benefit from PARPi-based therapies.Cancer genomics has highlighted the prevalence of sequence variants of unknown significance. Singh and colleagues hypothesized that a fraction of these mutations reflect RNA-related selection processes, thereby impacting RNA metabolism and contributing to oncogenic processes. Analysis of whole-genome sequencing (WGS) data from multiple cancers uncovered frequent mutations in binding sites for RNA binding proteins and splicing regulators. Furthermore, RNA sequencing (RNA-seq) data from the same specimens validated a change in RNA processing in association to these mutations. The study describes new alterations in cancer that impact RNA processing and proposes a systematic method for the interpretation of non-coding variants in cancer genomes.Histone 2B monoubiquitination (H2Bub1) is commonly lost during carcinogenesis and is deubiquitinated by ubiquitin-specific peptidase 22 (USP22). Here, the impact of USP22 on stem cell characteristics and cisplatin resistance was investigated in cancer-initiating cells (CICs) derived from human lung adenocarcinomas. Elevated USP22 expression associated with stem-like characteristics and chemotherapy resistance. Furthermore, ALDH1A3 which has been implicated in cisplatin resistance in lung adenocarcinoma was down-regulated upon USP22 knockdown. These data demonstrate that USP22 plays a critical role in tumorgenicity and cisplatin resistance in lung adenocarcinoma and may be a useful target for therapy.

Ubiquitin-Specific Peptidase 22 Contributes to Colorectal Cancer Stemness and Chemoresistance via Wnt/β-Catenin Pathway

Background/Aims: Two major barriers to the successful treatment of colorectal cancer (CRC) are the development of stem cell-like characteristics (stemness) and chemoresistance. Ubiquitin-specific peptidase 22 (USP22) is a deubiquitinating enzyme and putative CRC marker that has emerged as a potential cause of both phenomena in CRC. There is evidence that USP22 acts through the Wnt/β-catenin pathway and that downregulation of the latter may reduce chemoresistance. Methods: In this study, we used CRC tissue specimens from human patients as well as human CRC cell lines to evaluate the role of USP22 in CRC stemness and chemoresistance in vitro and in vivo. RT-PCR and western blot were used for gene expression analyses. Immunohistochemistry was performed for USP22 expression in clinical samples. CD133 levels were analyzed by flow cytometry. Sphere formation and MTT assays were used for self-renewal and proliferation analysis. Chemoresistance was evaluated by cell viability and sphere formation assays. Results: We found a significant increase of USP22 in recurrent CRC and chemoresistant CRC cells as compared to primary CRC and non-chemoresistant CRC cells, respectively. We then demonstrated that USP22 mediates CRC cell chemoresistance through the Wnt/β-catenin pathway and that reducing USP22 in CRC cells diminishes chemoresistance. Conclusions: Having established the crucial role of USP22 in CRC stemness and chemoresistance, this study suggests that USP22 may be an ideal genetic target in the treatment of chemoresistant CRC.

Ubiquitin Specific Peptidase 22 Regulates Histone H2B Mono-Ubiquitination and Exhibits Both Oncogenic and Tumor Suppressor Roles in Cancer.

Ubiquitin-Specific Peptidase 22 (USP22) is a ubiquitin hydrolase, notably catalyzing the removal of the mono-ubiquitin moiety from histone H2B (H2Bub1). Frequent overexpression of USP22 has been observed in various cancer types and is associated with poor patient prognosis. Multiple mechanisms have been identified to explain how USP22 overexpression contributes to cancer progression, and thus, USP22 has been proposed as a novel drug target in cancer. However, gene re-sequencing data from numerous cancer types show that USP22 expression is frequently diminished, suggesting it may also harbor tumor suppressor-like properties. This review will examine the current state of knowledge on USP22 expression in cancers, describe its impact on H2Bub1 abundance and present the mechanisms through which altered USP22 expression may contribute to oncogenesis, including an emerging role for USP22 in the maintenance of genome stability in cancer. Clarifying the impact aberrant USP22 expression and abnormal H2Bub1 levels have in oncogenesis is critical before precision medicine therapies can be developed that either directly target USP22 overexpression or exploit the loss of USP22 expression in cancer cells.

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 3ʹUTR. 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.

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.

The role of the cancer stem cell marker USP22 in tumors

Ubiquitin specific peptidase 22 (USP22) is one of the 11 known death-from-cancer signature genes. USP22 is also considered a cancer stem cell marker and is highly expressed in a variety of tumor types. USP22 alters the expression of tumor-associated genes (e.g., proto-oncogenes and tumor suppressor genes) and promotes tumor cell proliferation, invasion and metastasis via the modification of cell cycle activity and the activation of a variety of signaling pathways. In patients with tumors, USP22 expression is related to lymphatic metastasis, clinical stage of tumors, survival rate and a number of other factors. In addition, USP22 is considered an indicator of a poor prognosis and thus may be used to evaluate the prognosis of patients with tumors. As a potential cancer stem cell marker, USP22 may serve as a novel target for tumor therapies. Finally, USP22 also plays an important role in tumor development and progression.

MiR-34b inhibits nasopharyngeal carcinoma cell proliferation by targeting ubiquitin-specific peptidase 22.

ObjectivesThis study aimed to investigate the precise role of miR-34b in nasopharyngeal carcinoma (NPC).Materials and methods:The expression of miR-34b and transcription of ubiquitin-specific peptidase 22 (USP22) were examined using quantitative reverse transcription-polymerase chain reaction. Western blot analysis was used to measure the protein expression of USP22. A dualluciferase assay was used to investigate the interaction between miR-34b and USP22. Cell viability was determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. The cell cycle was analyzed by propidium iodide staining followed by flow cytometry analysis.ResultsmiR-34b was significantly downregulated in NPC tissues and NPC cell lines. Overexpression of miR-34b in NPC SUNE-6-10B cells inhibited cell viability and proliferation. USP22 was highly expressed in NPC cells and promoted cell viability and proliferation. Restoration of USP22 expression could reverse the effect of miR-34b on NPC cell viability and proliferation.ConclusionmiR-34b acts as a tumor suppressor in NPC, which is mediated via repression of the oncogene USP22.

Ubiquitin-specific peptidase 22 inhibits colon cancer cell invasion by suppressing the signal transducer and activator of transcription 3/matrix metalloproteinase 9 pathway.

Colon cancer is associated with increased cell migration and invasion. In the present study, the role of ubiquitin-specific peptidase 22 (USP22) in signal transducer and activator of transcription 3 (STAT3)-mediated colon cancer cell invasion was investigated. The messenger RNA levels of STAT3 target genes were measured by reverse transcription-quantitative polymerase chain reaction, following USP22 knockdown by RNA interference in SW480 colon cancer cells. The matrix metalloproteinase 9 (MMP9) proteolytic activity and invasion potential of SW480 cells were measured by zymography and Transwell assay, respectively, following combined USP22 and STAT3 short interfering (si)RNA treatment or STAT3 siRNA treatment alone. Similarly, a cell counting kit-8 assay was used to detect the proliferation potential of SW480 cells. The protein expression levels of USP22, STAT3 and MMP9 were detected by immunohistochemistry in colon cancer tissue microarrays (TMAs) and the correlation between USP22, STAT3 and MMP9 was analyzed. USP22/STAT3 co-depletion partly rescued the MMP9 proteolytic activity and invasion of SW480 cells, compared with that of STAT3 depletion alone. However, the proliferation of USP22/STAT3si-SW480 cells was decreased compared with that of STAT3si-SW480 cells. USP22 expression was positively correlated with STAT3 and MMP9 expression in colon cancer TMAs. In conclusion, USP22 attenuated the invasion capacity of colon cancer cells by inhibiting the STAT3/MMP9 signaling pathway.