Implication of USP22 in the regulation of BMI-1, c-Myc, p16INK4a, p14ARF, and cyclin D2 expression in primary colorectal carcinomas. ACTA ACUST UNITED AC. 2010;19:194-200. [PMID: 21052002 DOI: 10.1097/pdm.0b013e3181e202f2]

A new digital droplet PCR method for looking at epigenetics in diffuse large B-cell lymphomas: The role of BMI1, EZH2, and USP22 genes

INTRODUCTION

Epigenetics has been shown to be relevant in oncology: BMI1 overexpression has been reported in leukemias, EZH2 mutations have been found in follicular lymphoma, and USP22 seems to stabilize BMI1 protein. In this study, we measured the expression of BMI1, EZH2, and USP22 in lymph nodes from 56 diffuse large B-cell lymphoma (DLBCL) patients.

METHODS

A new multiplex digital droplet PCR (ddPCR) has been set up to measure the expression of 4 genes (BMI1, EZH2, USP22, and GAPDH) in the same reaction on RNA extracted from paraffin-embedded tissues.

RESULTS

The specificity of ddPCR was confirmed by a 100% alignment on the BLAST platform and its repeatability demonstrated by duplicates. A strict correlation between expression of BMI1 and EZH2 and BMI1 and USP22 has been found, and high expression of these genes was correlated with extra-nodal lymphomas. Progression-free survival (PFS) and overall survival (OS) were conditioned by IPI, bone marrow infiltration, and the complete response achievement. High levels of BMI1 and USP22 did not condition the response to therapy, but impaired the PFS, especially for patients defined at "high risk" based on the cell of origin (no germinal center [GCB]), high BCL2 expression, and IPI 3-5. In this subgroup, the probability of relapse/progression was twice higher than that of patients carrying low BMI1 and USP22 levels.

CONCLUSION

High expression of BMI1 and of USP22 might be a poor prognostic factor in DLBCL, and might represent the target for novel inhibitors.

Hepatocyte growth factor promotes melanoma metastasis through ubiquitin-specific peptidase 22-mediated integrins upregulation

Hepatocyte growth factor (HGF) plays a critical role in promoting tumor migration, invasion, and metastasis, partly by upregulating integrins. The molecular mechanisms behind how HGF facilitates integrin-mediated tumorigenesis are not fully understood. In this study, we demonstrate that the ubiquitin-specific peptidase 22 (USP22) is essential for HGF-induced melanoma metastasis. HGF treatment dramatically increased the expression of both USP22 and multiple integrin family members in particular ITGAV, ITGB3, and ITGA1. An unbiased analysis of the TCGA database reveals integrins as common downstream targets of both USP22 and HGF across multiple human cancer types. Notably, CRISPR-mediated deletion of USP22 completely eliminates HGF-induced integrin expression in melanoma cells. At the molecular level, USP22 acts as a bona fide deubiquitinase for Sp1, a transcription factor for the ITGAV, ITGB3, and ITGA1 genes. USP22 interacts with and inhibits Sp1 ubiquitination, protecting against Sp1 proteasomal degradation. Supporting this, immunohistology analysis detects a positive correlation among USP22, Sp1, and integrin αv in human melanoma tissues. This study identifies the death from the signature gene USP22 as a critical positive regulator for HGF-induced integrin expression by deubiquitinating the Sp1 transcription factor during melanoma metastasis.

Comprehensive analysis of the role of ubiquitin-specific peptidases in colorectal cancer: A systematic review

BACKGROUND

Colorectal cancer (CRC) is the third most frequent and the second most fatal cancer. The search for more effective drugs to treat this disease is ongoing. A better understanding of the mechanisms of CRC development and progression may reveal new therapeutic strategies. Ubiquitin-specific peptidases (USPs), the largest group of the deubiquitinase protein family, have long been implicated in various cancers. There have been numerous studies on the role of USPs in CRC; however, a comprehensive view of this role is lacking.

AIM

To provide a systematic review of the studies investigating the roles and functions of USPs in CRC.

METHODS

We systematically queried the MEDLINE (via PubMed), Scopus, and Web of Science databases.

RESULTS

Our study highlights the pivotal role of various USPs in several processes implicated in CRC: Regulation of the cell cycle, apoptosis, cancer stemness, epithelial-mesenchymal transition, metastasis, DNA repair, and drug resistance. The findings of this study suggest that USPs have great potential as drug targets and noninvasive biomarkers in CRC. The dysregulation of USPs in CRC contributes to drug resistance through multiple mechanisms.

CONCLUSION

Targeting specific USPs involved in drug resistance pathways could provide a novel therapeutic strategy for overcoming resistance to current treatment regimens in CRC.

Potent macrocycle inhibitors of the human SAGA deubiquitinating module

The Spt-Ada-Gcn5 acetyltransferase (SAGA) transcriptional coactivator contains a four-protein subcomplex called the deubiquitinating enzyme (DUB) module that removes ubiquitin from histone H2B-K120. The human DUB module contains the catalytic subunit ubiquitin-specific protease 22 (USP22), which is overexpressed in a number of cancers that are resistant to available therapies. We screened a massive combinatorial library of cyclic peptides and identified potent inhibitors of USP22. The top hit was highly specific for USP22 compared with a panel of 44 other human DUBs. Cells treated with peptide had increased levels of H2B monoubiquitination, demonstrating the ability of the cyclic peptides to enter human cells and inhibit H2B deubiquitination. These macrocycle inhibitors are, to our knowledge, the first reported inhibitors of USP22/SAGA DUB module and show promise for development.

Operative ubiquitin-specific protease 22 deubiquitination confers a more invasive phenotype to cholangiocarcinoma

Oncogenic ubiquitin-specific protease 22 (USP22) is implicated in a variety of tumours; however, evidence of its role and underlying molecular mechanisms in cholangiocarcinoma (CCA) development remains unknown. We collected paired tumour and adjacent non-tumour tissues from 57 intrahepatic CCA (iCCA) patients and evaluated levels of the USP22 gene and protein by qPCR and immunohistochemistry. Both the mRNA and protein were significantly upregulated, correlated with the malignant invasion and worse OS of iCCA. In cell cultures, USP22 overexpression increased CCA cell proliferation and mobility, and induced epithelial-to-mesenchymal transition (EMT). Upon an interaction, USP22 deubiquitinated and stabilized sirtuin-1 (SIRT1), in conjunction with Akt/ERK activation. In implantation xenografts, USP22 overexpression stimulated tumour growth and metastasis to the lungs of mice. Conversely, the knockdown by USP22 shRNA attenuated the tumour growth and invasiveness in vitro and in vivo. Furthermore, SIRT1 overexpression reversed the USP22 functional deficiency, while the knockdown acetylated TGF-β-activated kinase 1 (TAK1) and Akt. Our present study defines USP22 as a poor prognostic predictor in iCCA that cooperates with SIRT1 and facilitates tumour development.

Dissenting degradation: Deubiquitinases in cell cycle and cancer

Since its discovery forty years ago, protein ubiquitination has been an ever-expanding field. Virtually all biological processes are controlled by the post-translational conjugation of ubiquitin onto target proteins. In addition, since ubiquitin controls substrate degradation through the action of hundreds of enzymes, many of which represent attractive therapeutic candidates, harnessing the ubiquitin system to reshape proteomes holds great promise for improving disease outcomes. Among the numerous physiological functions controlled by ubiquitin, the cell cycle is among the most critical. Indeed, the discovery that the key drivers of cell cycle progression are regulated by the ubiquitin-proteasome system (UPS) epitomizes the connection between ubiquitin signaling and proliferation. Since cancer is a disease of uncontrolled cell cycle progression and proliferation, targeting the UPS to stop cancer cells from cycling and proliferating holds enormous therapeutic potential. Ubiquitination is reversible, and ubiquitin is removed from substrates by catalytic proteases termed deubiquitinases or DUBs. While ubiquitination is tightly linked to proliferation and cancer, the role of DUBs represents a layer of complexity in this landscape that remains poorly captured. Due to their ability to remodel the proteome by altering protein degradation dynamics, DUBs play an important and underappreciated role in the cell cycle and proliferation of both normal and cancer cells. Moreover, due to their enzymatic protease activity and an open ubiquitin binding pocket, DUBs are likely to be important in the future of cancer treatment, since they are among the most druggable enzymes in the UPS. In this review we summarize new and important findings linking DUBs to cell cycle and proliferation, as well as to the etiology and treatment of cancer. We also highlight new advances in developing pharmacological approaches to attack DUBs for therapeutic benefit.

Assessment of clinicopathological and prognostic relevance of BMI-1 in patients with colorectal cancer: A meta-analysis

B-cell-specific Moloney leukemia virus insertion site 1 (BMI-1) is one of the stemness markers. The prognostic and clinicopathological effects of BMI-1 expression in colorectal cancer (CRC) have been in dispute with different studies. Eligible studies were retrieved from international databases up to December 2019. Studies with a relationship between the clinicopathological and prognostic value of CRC patients with BMI-1 expression were selected. The correlations in the random-effect model were evaluated using the hazard ratios, odds ratio, and 95% confidence intervals (CIs). A total of nine studies comprising Asian cases (seven studies) and European cases (two studies) covering 1,294 samples of CRC were included for this meta-analysis. The analysis suggested that in Asian cases, increased expression of BMI-1 was associated with poor overall survival (OS) and death-free survival, whereas in European populations, high expression of BMI-1 was associated with better OS. Also, overexpression of BMI-1 in the Asian population was associated with the tumor size, distant metastasis, and patient's gender and age. Results suggested that high expression of BMI-1 can be involved in the progression and invasion of CRC, and so its inhibitor-based therapies could be used to prevent the progression of CRC.

USP22 positively modulates ERα action via its deubiquitinase activity in breast cancer

Estrogen receptor α (ERα) is the crucial factor in ERα-positive breast cancer progression. Endocrine therapies targeting ERα signaling is one of the widely used therapeutic strategies for breast cancer. However, a large number of the patients become refractory to therapy. Abnormal expression of ERα co-regulator facilitates breast cancer development and tendency of endocrine resistance. Thus, it is necessary to discover the novel co-regulators modulating ERα action. Here, we demonstrate that histone deubiquitinase USP22 is highly expressed in breast cancer samples compared with that in the benign tissue, and high expression of USP22 was significantly associated with poorer overall survival in BCa samples. Moreover, USP22 associates with ERα to be involved in maintenance of ERα stability. USP22 enhances ERα-induced transactivation. We further provide the evidence that USP22 is recruited together with ERα to cis-regulatory elements of ERα target gene. USP22 promotes cell growth even under hypoxia condition and with the treatment of ERα antagonist in breast cancer cells. Importantly, the deubiquitination activity of USP22 is required for its functions on maintenance of ERα stability, thereby enhancing ERα action and conferring endocrine resistance in breast cancer.

Identification of Prognostic Biomarkers and Drugs Targeting Them in Colon Adenocarcinoma: A Bioinformatic Analysis

Objective: To identify prognostic biomarkers and drugs that target them in colon adenocarcinoma (COAD) based on the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus databases. Methods: The TCGA dataset was used to identify the top 50 upregulated differentially expressed genes (DEGs), and Gene Expression Omnibus profiles were used for validation. Survival analyses were conducted with the TCGA dataset using the RTCGAToolbox package in the R software environment. Drugs targeting the candidate prognostic biomarkers were searched in the DrugBank and herbal databases. Results: Among the top 50 upregulated DEGs in patients with COAD in the TCGA dataset, the Wnt signaling pathway and cytokine-cytokine receptor interactions and pathways in cancer Kyoto Encyclopedia of Genes and Genomes pathway analysis were enriched in DEGs. Tissue development and regulation of cell proliferation were the main Gene Ontology biological processes associated with upregulated DEGs. MYC and KLK6 were overexpressed in tumors validated in the TCGA, GSE41328, and GSE113513 databases (all P < .001) and were significantly associated with overall survival in patients with COAD (P = .021 and P = .047). Nadroparin and benzamidine were identified as inhibitors of MYC and KLK6 in DrugBank, and 8 herbs targeting MYC, including Da Huang (Radix Rhei Et Rhizome), Hu Zhang (Polygoni Cuspidati Rhizoma Et Radix), Huang Lian (Coptidis Rhizoma), Ban Xia (Arum Ternatum Thunb), Tu Fu Ling (Smilacis Glabrae Rhixoma), Lei Gong Teng (Tripterygii Radix), Er Cha (Catechu), and Guang Zao (Choerospondiatis Fructus), were identified. Conclusion: MYC and KLK6 may serve as candidate prognostic predictors and therapeutic targets in patients with COAD.

USP22-dependent HSP90AB1 expression promotes resistance to HSP90 inhibition in mammary and colorectal cancer

As a member of the 11-gene “death-from-cancer” gene expression signature, overexpression of the Ubiquitin-Specific Protease 22 (USP22) was associated with poor prognosis in various human malignancies. To investigate the function of USP22 in cancer development and progression, we sought to detect common USP22-dependent molecular mechanisms in human colorectal and breast cancer cell lines. We performed mRNA-seq to compare gene expression profiles of various colorectal (SW837, SW480, HCT116) and mammary (HCC1954 and MCF10A) cell lines upon siRNA-mediated knockdown of USP22. Intriguingly, while USP22 depletion had highly heterogeneous effects across the cell lines, all cell lines displayed a common reduction in the expression of Heat Shock Protein 90 Alpha Family Class B Member 1 (HSP90AB1). The downregulation of HSP90AB1 was confirmed at the protein level in these cell lines as well as in colorectal and mammary tumors in mice with tissue-specific Usp22 deletions. Mechanistically, we detected a significant reduction of H3K9ac on the HSP90AB1 gene in USP22-deficient cells. Interestingly, USP22-deficient cells displayed a high dependence on HSP90AB1 expression and diminishing HSP90 activity further using the HSP90 inhibitor Ganetespib resulted in increased therapeutic vulnerability in both colorectal and breast cancer cells in vitro. Accordingly, subcutaneously transplanted CRC cells deficient in USP22 expression displayed increased sensitivity towards Ganetespib treatment in vivo. Together, we discovered that HSP90AB1 is USP22-dependent and that cooperative targeting of USP22 and HSP90 may provide an effective approach to the treatment of colorectal and breast cancer.

Oncogenic USP22 supports gastric cancer growth and metastasis by activating c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling

In this study, we investigated the role of ubiquitin-specific protease 22 (USP22) in the growth and progression of gastric cancer (GC). USP22 mRNA and protein levels were significantly higher in GC tissue samples and GC cell lines than in adjacent noncancerous tissue samples and a normal gastric mucosal epithelial cell line (GES1), respectively. USP22 knockdown significantly decreased in vitro survival, proliferation, migration, and invasiveness of GC cells compared with the controls. Western blot analysis of control and USP22-silenced GC cells showed that USP22 modulates the c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling pathways. Subcutanenous injection of USP22-silenced GC cells into SCID mice generated significantly smaller xenograft tumors than did control cells. Moreover, USP22-silenced GC cells showed less lung metastasis than the controls following tail vein injection in SCID mice. In addition, high USP22 expression correlated positively with tumor size, advanced stage and metastasis, and correlated negatively with tumor differentiation and prognosis in GC patients. These results show that USP22 regulates growth and progression of GC via the c-Myc/NAMPT/SIRT1-dependent FOXO1 and YAP signaling pathways.

USP22 exerts tumor-suppressive functions in colorectal cancer by decreasing mTOR activity

USP22, the deubiquitinating subunit of the SAGA transcriptional cofactor complex, is a member of an 11-gene "death-from-cancer" signature. USP22 has been considered an attractive therapeutic target since high levels of its expression were associated with distant metastasis, poor survival, and high recurrence rates in a wide variety of solid tumors, including colorectal cancer (CRC). We sought to investigate the role of Usp22 during tumorigenesis in vivo using a mouse model for intestinal carcinogenesis with a tissue-specific Usp22 ablation. In addition, we assessed the effects of USP22 depletion in human CRC cells on tumorigenic potential and identified underlying molecular mechanisms. For the first time, we report that USP22 has an unexpected tumor-suppressive function in vivo. Intriguingly, intestine-specific Usp22 deletion exacerbated the tumor phenotype caused by Apc mutation, resulting in significantly decreased survival and higher intestinal tumor incidence. Accordingly, human CRC cells showed increased tumorigenic properties upon USP22 reduction in vitro and in vivo and induced gene expression signatures associated with an unfavorable outcome in CRC patients. Notably, USP22 loss resulted in increased mTOR activity with the tumorigenic properties elicited by the loss of USP22 being reversible by mTOR inhibitor treatment in vitro and in vivo. Here, we demonstrate that USP22 can exert tumor-suppressive functions in CRC where its loss increases CRC burden by modulating mTOR activity. Importantly, our data uncover a tumor- and context-specific role of USP22, suggesting that USP22 expression could serve as a marker for therapeutic stratification of cancer patients.

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.

MicroRNA-485-5p reduces O-GlcNAcylation of Bmi-1 and inhibits colorectal cancer proliferation

Emerging evidences showed that miRNAs are involved in the oncogenesis of many cancers. Here, miRNA microarray analysis was performed to screen the significant miRNAs involved in the progression of colorectal cancer (CRC), miR-485-5p was chosen for further study. We found that the expression of miR-485-5p was significantly lower in CRC specimens and cell lines. In addition, low expression level of miR-485-5p is correlated with tumor progression and poor survival in CRC patients. Based on in vitro and in vivo assays, we found that miR-485-5p significantly inhibits CRC proliferation. Moreover, our results showed that miR-485-5p inhibits cell proliferation by reducing Bmi-1 protein expression, which has been reported to control the proliferation of many cancers. Mechanistically, OGT is a direct target of miR-485-5p, and miR-485-5p could inhibit the O-GlcNAcylation level of Bmi-1 by OGT. Overall, these results suggested that as a tumor suppressor, miR-485-5p may regulate CRC cells proliferation, which could regulate the O-GlcNAcylation and the stability of Bmi-1 through targeting OGT. This may give insight into a novel mechanism and therapy of CRC growth.

Downregulation of Ubiquitin-Specific Protease 22 Inhibits Proliferation, Invasion, and Epithelial-Mesenchymal Transition in Osteosarcoma Cells

Ubiquitin-specific protease 22 (USP22), a novel deubiquitinating enzyme, belongs to an extended family of proteins that have ubiquitin hydrolase activity. Recently, USP22 has attracted widespread attention because of its implication in carcinogenesis. However, there have been no studies, to our knowledge, investigating the expression of USP22 in osteosarcoma (OS) and its association with OS progression. In this study, we explored the role of USP22 in OS. We demonstrated that USP22 was highly expressed in OS tissue and cell lines. Downregulation of USP22 inhibited OS cell proliferation, invasion, and epithelial-mesenchymal transition (EMT) in vitro. In addition, downregulation of USP22 suppressed OS tumor growth and metastasis in vivo. We also found that the PI3K/Akt signaling pathway was involved in the tumor-promoting effect of USP22 on OS progression. Taken together, we suggest USP22 as a novel therapeutic target for OS.

Usp22 deficiency impairs intestinal epithelial lineage specification in vivo

Epigenetic regulatory mechanisms play a central role in controlling gene expression during development, cell differentiation and tumorigenesis. Monoubiquitination of histone H2B is one epigenetic modification which is dynamically regulated by the opposing activities of specific ubiquitin ligases and deubiquitinating enzymes (DUBs). The Ubiquitin-specific Protease 22 (USP22) is the ubiquitin hydrolase component of the human SAGA complex which deubiquitinates histone H2B during transcription. Recently, many studies have investigated an oncogenic potential of USP22 overexpression. However, its physiological function in organ maintenance, development and its cellular function remain largely unknown. A previous study reported embryonic lethality in Usp22 knockout mice. Here we describe a mouse model with a global reduction of USP22 levels which expresses the LacZ gene under the control of the endogenous Usp22 promoter. Using this reporter we found Usp22 to be ubiquitously expressed in murine embryos. Notably, adult Usp22^lacZ/lacZ displayed low residual Usp22 expression levels coupled with a reduced body size and weight. Interestingly, the reduction of Usp22 significantly influenced the frequency of differentiated cells in the small intestine and the brain while H2B and H2Bub1 levels remained constant. Taken together, we provide evidence for a physiological role for USP22 in controlling cell differentiation and lineage specification.

The prognostic value of polycomb group protein B-cell-specific moloney murine leukemia virus insertion site 1 in stage II colon cancer patients

The aim of this study was to investigate the prognostic value of B-cell-specific moloney murine leukemia virus insertion site 1 (BMI1) protein expression in primary tumors of stage II colon cancer patients. BMI1 protein expression was assessed by immunohistochemistry in a retrospective patient cohort consisting of 144 stage II colon cancer patients. BMI1 expression at the invasive front of the primary tumors correlated with mismatch repair status of the tumors. Furthermore, BMI1 expression at the luminal surface correlated with T-stage, tumor location, and the histological subtypes of the tumors. In a univariate Cox proportional hazard analysis, no statistical significant association between risk of relapse and BMI1 protein expression at the invasive front (HR: 1.12; 95% CI 0.78-1.60; p = 0.53) or at the luminal surface of the tumor (HR: 1.06; 95% CI 0.75-1.48; p = 0.70) was found. Likewise, there was no association between 5-year overall survival and BMI1 expression at the invasive front (HR: 1.12; 95% CI 0.80-1.56; p = 0.46) or at the luminal surface of the tumor (HR: 1.16; 95% CI 0.86-1.60; p = 0.33). In conclusion, BMI1 expression in primary tumors of stage II colon cancer patients could not predict relapse or overall survival of the patients, thus having a limited prognostic value in stage II colon cancer patients.

High USP22 expression indicates poor prognosis in hepatocellular carcinoma

Ubiquitin-specific protease 22 (USP22) removes ubiquitin from histones, thus regulating gene transcription. The expression frequency and expression levels of USP22 were significantly higher in hepatocellular carcinoma (HCC) than in normal liver tissues. High USP22 expression in HCC was significantly correlated with clinical stage and tumor grade. Kaplan-Meier analysis showed that elevated USP22 expression predicted poorer overall survival and recurrence-free survival. High USP22 expression was also associated with shortened survival time in patients at advanced tumor stages and with high grade HCC. Multivariate analyses revealed that USP22 expression is an independent prognostic parameter in HCC. These findings provide evidence that high USP22 expression might be important in tumor progression and serves as an independent molecular marker for poor HCC prognosis. Thus, USP22 overexpression identifies patients at high risk and represents a novel therapeutic molecular target for this tumor.

Ubiquitin proteasome system research in gastrointestinal cancer

The ubiquitin proteasome system (UPS) is important for the degradation of proteins in eukaryotic cells. It is involved in nearly every cellular process and plays an important role in maintaining body homeostasis. An increasing body of evidence has linked alterations in the UPS to gastrointestinal malignancies, including esophageal, gastric and colorectal cancers. Here, we summarize the current literature detailing the involvement of the UPS in gastrointestinal cancer, highlighting its role in tumor occurrence and development, providing information for therapeutic targets research and anti-gastrointestinal tumor drug design.

Expression of USP22 and Survivin is an indicator of malignant behavior in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common primary malignant liver tumor type, ranking as the third leading cause of all cancer-related deaths in the world. The post-surgical 5-year survival rate is low, largely due to the high recurrence rate. Therefore, the identification of target molecules that control the biological characteristics of HCC is of great importance. Ubiquitin-specific protease 22 (USP22) is a newly discovered deubiquitinating enzyme and is a cancer stem cell marker that plays a role in tumorigenesis, therapy resistance and cell cycle progression. Survivin is a member of the inhibitor of apoptosis protein (IAP) family and is known to function either as an inhibitor for apoptosis or as a regulator of cell division. Levels of survivin are correlated with the aggressiveness of tumors and a poor prognosis in various cancers including HCC. In the present study, we examined the USP22 expression and its association with survivin expression and clinicopathological features in HCC. First, we examined the expression of USP22 and survivin in 151 HCC cases by immunohistochemistry. High expression of USP22 and survivin was frequently observed in HCC cases, in comparison with normal adjacent liver tissues. Expression of USP22 and survivin was well correlated with malignant behavior including tumor size, stage and differentiation in HCC cases. Importantly, HCC patients with high expression of USP22 and survivin showed poor prognosis. USP22 expression was well correlated with survivin expression in HCC cases. This correlation was confirmed in HCC cell lines and tissues by RT-PCR and western blot analysis. Next, to investigate the biological role of USP22 in HCC, we examined the effect of USP22 knockdown on the cell growth and the expression of cell cycle-related protein including survivin in HCC cells. USP22 siRNA suppressed cell growth. Moreover, USP22 siRNA decreased survivin expression together with upregulation of CDK inhibitor, p21 and downregulation of cyclin B. These findings suggest that USP22 may be involved in HCC progression in cooperation with survivin. We suggest that USP22 can be useful as a new prognostic marker and therapeutic target in HCC patients.

Decreased miR-154 expression and its clinical significance in human colorectal cancer

Background

miRNA-154 (miR-154) has been identified as a tumor suppressor in several types of human cancers. However, its clinical significance in colorectal cancer (CRC) is still unclear. The aim of this study was to analyze the association of miR-154 expression with clinicopathologic features and prognosis in CRC patients.

Methods

Quantitative RT-PCR was performed to evaluate miR-154 levels in 169 pairs of CRC specimens and adjacent noncancerous tissues. Then, the associations of miR-154 expression with clinicopathological factors or survival of patients suffering CRC were determined.

Results

The expression levels of miR-154 in CRC tissues were significantly lower than those in corresponding noncancerous tissues (P < 0.001). Decreased miR-154 expression was significantly associated with large tumor size, positive lymph node metastasis, and advanced clinical stage. Moreover, the univariate analysis demonstrated that CRC patients with low miR-154 expression had poorer overall survival (P = 0.006). The multivariate analysis identified low miR-154 expression as an independent predictor of poor survival.

Conclusions

These findings suggested that miR-154 downregulation may be associated with tumor progression of CRC, and that this miR may be an independent prognostic marker for CRC patients.

Clinical significance of expression of Bmi-1 and Mina53 in colorectal carcinoma

AIM: To investigate the clinicopathological significance of expression of B-cell-specific moloney murine leukemia virus insertion site 1 (Bmi-1) and myc-induced nuclear antigen with a molecular mass of 53 kDa (Mina53) in colorectal carcinoma.

METHODS: The expression of Bmi-1 and Mina53 proteins was detected by immunohistochemistry in 56 colorectal cancer samples and matched tumor-adjacent normal tissue samples. The correlation between the expression of these proteins and the clinicopathologic features of colorectal carcinoma was analyzed.

RESULTS: The positive rates of Bmi-1 expression and Mina53 in colorectal cancer were significantly higher than those in matched tumor-adjacent normal tissue (80.4% vs 35.7%, 73.2% vs 19.6%, χ² = 22.913, 32.308, P < 0.05 for both). Expression of Bmi-1 and Mina53 was significantly associated with tumor differentiation, lymph node metastasis and tumor infiltration depth in colorectal carcinoma (P < 0.05 for all), but not with age or gender (P > 0.05 for both). A positive correlation was noted between the expression of Bmi-1 and that of Mina53 in colorectal carcinoma (r = 0.296, P < 0.05).

CONCLUSION: High expression of Bmi-1 and Mina53 proteins may participate in the occurrence, progression and prognosis of colorectal carcinoma. Combined detection of the expression of these proteins is helpful to the diagnosis and evaluation of the prognosis of colorectal carcinoma.

Deubiquitinases and the new therapeutic opportunities offered to cancer

Deubiquitinases (DUBs) play important roles and therefore are potential drug targets in various diseases including cancer and neurodegeneration. In this review, we recapitulate structure-function studies of the most studied DUBs including USP7, USP22, CYLD, UCHL1, BAP1, A20, as well as ataxin 3 and connect them to regulatory mechanisms and their growing protein interaction networks. We then describe DUBs that have been associated with endocrine carcinogenesis with a focus on prostate, ovarian, and thyroid cancer, pheochromocytoma, and adrenocortical carcinoma. The goal is enhancing our understanding of the connection between dysregulated DUBs and cancer to permit the design of therapeutics and to establish biomarkers that could be used in diagnosis and prognosis.

USP22 promotes the G1/S phase transition by upregulating FoxM1 expression via β-catenin nuclear localization and is associated with poor prognosis in stage II pancreatic ductal adenocarcinoma

Ubiquitin-specific protease 22 (USP22), a newly discovered member of ubiquitin hydrolase family, exhibits a critical function in cell cycle progression and tumorigenesis. The forkhead box M1 (FoxM1) transcription factor plays a crucial role in cell proliferation, differentiation and transformation. However, the expression and functions of USP22 in pancreatic ductal adenocarcinoma (PDA) and whether FoxM1 is involved in USP22-mediated cell cycle regulation have not been studied. We examined the expression of USP22 and FoxM1 in 136 stage II PDA tissues by immunohistochemistry. Clinical significance was analyzed by multivariate Cox regression analysis, Kaplan-Meier curves and log-rank test. RT-PCR, western blot analysis, luciferase and immunofluorescence assays were used to investigate the molecular function of USP22 and FoxM1 in PDA fresh tissues and cell lines. USP22 and FoxM1 were significantly upregulated in PDA tissues compared with the paired normal carcinoma-adjacent tissues. A statistical correlation was observed between USP22 and FoxM1 expression. The expression of USP/FoxM1 and co-expression of both factors correlated with tumor size, lymph node metastasis and overall survival. Multivariate Cox regression analysis revealed that the expression of USP22/FoxM1, especially the co-expression of both factors, is an independent, unfavorable prognostic factor. USP22 overexpression is accompanied by an increase in FoxM1 expression and USP22 increases FoxM1 expression to promote G1/S transition and cell proliferation through promoting β-catenin nuclear translocation in PDA cell lines. USP22 promotes the G1/S phase transition by upregulating FoxM1 expression via promoting β-catenin nuclear localization. USP22 and FoxM1 may act as prognostic markers and potential targets for PDA.

Ubiquitin-specific protease 22: a novel molecular biomarker in glioma prognosis and therapeutics

Ubiquitin-specific protease 22 (USP22) exhibits an important function in tumor progression and oncogenesis. The aim of this study was to investigate the role of USP22 and the association with its potential targets in patients with glioma. To our knowledge, this is the first study that determines the relationship between USP22 expression and clinicopathological significance in glioma. In our study, USP22 protein levels were detected by Western blot analysis. The protein levels of USP22 in glioma tissues were significantly higher than non-tumors. The immunohistochemistry results showed that USP22 protein was overexpressed in glioma tissues compared with non-tumors. The higher the grade of gliomas, the higher the level of USP22 expression. Further, the results of Kaplan-Meier analysis indicated that patients with high USP22 expression had significantly worse overall survival than patients with low expression of USP22. It suggested that USP22 overexpression may be associated with poor prognosis in patients with glioma. It may represent a novel prognostic biomarker or a target for improving the treatment efficiency of patients with glioma.

RNA interference in the treatment of colon cancer

Colorectal cancer is the third most common cancer in both men and women and has shown a progressive increase over the past 20 years. Current chemotherapy has major limitations, and a novel therapeutic approach is required. Given that neoplastic transformation of colon epithelial cells is a consequence of genetic and epigenetic alterations, RNA interference (RNAi) has been proposed as a new therapeutic strategy that offers important advantages over conventional treatments, with high specificity and potency and low toxicity. RNAi has been employed as an effective tool to study the function of genes, preventing their expression and leading to the development of new approaches to cancer treatment. In malignancies, including colon cancer, RNAi is being used for "silencing" genes that are deregulated by different processes such as gene amplification, mutation, or overexpression and may be the cause of oncogenesis. This strategy not only provides information on the involvement of certain genes in colon cancer, but also opens up a new perspective for its treatment. However, most studies have used adenovirus or lentivirus vectors to transport RNAi into tumor cells or tumors in animal models, because several technical obstacles must be overcome before RNAi can be used in the clinical setting. The aim of this study was to review current knowledge on the use of RNAi techniques in the treatment of colon cancer.

Deubiquitinating Enzymes as Novel Targets for Cancer Therapies

Most ubiquitinated proteins can be recognized and degraded by the 26S proteasome. In the meantime, protein deubiquitination by various deubiquitinating enzymes (DUBs) regulates protein stability within cells, and it can counterbalance intracellular homeostasis mediated by ubiquitination. Numerous reports have demonstrated that an aberrant process of the ubiquitin-proteasome pathway (UPP) regulated by the ubiquitination and deubiquitination systems results in failure of balancing between protein stability and degradation, and this failure can lead to tumorigenesis in various organs and tissues of mammals. The identification of molecular properties for various DUBs is very critical to understand cancer development and tumorigenesis. Therefore, knowledge of DUBs and their association with cancer and diseases is indispensible for developing effective inhibitors for DUBs. This chapter describes various features and functions of cancer-related DUBs. In addition, we summarize several inhibitors that specifically target certain DUBs in cancer and suggest that DUBs may be one of the most ideal and attractive therapeutic targets.

RNA interference-mediated USP22 gene silencing promotes human brain glioma apoptosis and induces cell cycle arrest

Ubiquitin-specific protease 22 (USP22) is a novel tumor stem cell marker that plays a key role in tumorigenesis and cell cycle progression. However, the effect of silencing the USP22 gene on human brain glioma cell growth is not well understood. In the present study, high gene expression of USP22 was identified in human brain glioma cells. In addition, RNA interference technology was used to silence USP22 gene expression in human brain glioma cells. Silencing the USP22 gene was found to effectively inhibit proliferation of human brain glioma cells, resulting in cell apoptosis and cell cycle arrest at the G₂/M phase. USP22 silencing was also found to lead to reduced expression of cell cycle proteins, including CDK1, CDK2 and CyclinB1. In summary, in this study the USP22 gene was demonstrated to play a key regulatory role in the growth of human brain glioma cells by affecting progression of apoptosis and the cell cycle.

USP22 nuclear expression is significantly associated with progression and unfavorable clinical outcome in human esophageal squamous cell carcinoma

PURPOSE

To detect the expression levels of ubiquitin-specific protease 22 (USP22) in human esophageal squamous cell carcinoma (ESCC) and to correlate it with clinicopathologic and prognostic data.

METHODS

The immunoreactivity of USP22 protein was analyzed in 157 pathologically characterized ESCC tissues by immunohistochemistry. All statistical analyses were performed with SPSS statistical software to evaluate the association of USP22 protein with clinicopathologic factors and survival.

RESULTS

High expression of USP22 protein was detected in 50.96 % of 157 ESCC tissues and significantly associated with invasion depth, lymph node metastasis, pathologic stage and tumor relapse (P < 0.05, respectively). Univariate survival analysis showed that patients with high expression of USP22 protein had a significantly poorer 5-year disease-specific survival (P = 0.002), and multivariate survival analysis showed that high expression of USP22 protein was an independent prognosticator for unfavorable disease-specific survival (P = 0.039). Further survival analysis stratified by pathologic stage demonstrated that high expression of USP22 protein significantly predicted unfavorable clinical outcome (P = 0.029) among patients with pathologic stage II(b)-III diseases.

CONCLUSION

USP22 protein plays an essential role in ESCC progression and has clinical potentials not only as a promising biomarker to identify the subgroup of patients with more aggressive tumors and poor prognostic potential but also as an attractively therapeutic target for ESCC.

Rac1 signalling modulates a STAT5/BCL-6 transcriptional switch on cell-cycle-associated target gene promoters

Gene expression depends on binding of transcriptional regulators to gene promoters, a process controlled by signalling pathways. The transcriptional repressor B-cell lymphoma (BCL)-6 downregulates genes involved in cell-cycle progression and becomes inactivated following phosphorylation by the Rac1 GTPase-activated protein kinase PAK1. Interestingly, the DNA motifs recognized by BCL-6 and signal transducers and activators of transcription 5 (STAT5) are similar. Because STAT5 stimulation in epithelial cells can also be triggered by Rac1 signalling, we asked whether both factors have opposing roles in transcriptional regulation and whether Rac1 signalling may coordinate a transcription factor switch. We used chromatin immunoprecipitation to show that active Rac1 promotes release of the repressor BCL-6 while increasing binding of STAT5A to a BCL-6-regulated reporter gene. We further show in colorectal cell lines that the endogenous activation status of the Rac1/PAK1 pathway correlated with the phosphorylation status of BCL-6 and STAT5A. Three cellular genes (cyclin D2, p15^INK4B, small ubiquitin-like modifier 1) were identified to be inversely regulated by BCL-6 and STAT5A and responded to Rac1 signalling with increased expression and corresponding changes in promoter occupancy. Together, our data show that Rac1 signalling controls a group of target genes that are repressed by BCL-6 and activated by STAT5A, providing novel insights into the modulation of gene transcription by GTPase signalling.

CIP2A overexpression is associated with c-Myc expression in colorectal cancer

BACKGROUND

To improve the prognostic evaluation of colorectal cancer requires new molecular markers. Cancerous inhibitor of protein phosphatase 2A (CIP2A) serves as an oncoprotein by targeting PP 2A-mediated inhibition of c-Myc. A prognostic role for CIP2A has been demonstrated in gastric, lung and tongue cancers.

RESULTS

CIP2A was overexpressed in 661 (87.9%) specimens. CIP2A overexpression was associated with tumor differentiation grade (p = 0.014), p53 immunopositivity (p = 0.042), EGFR immunopositivity (p = 0.007) and c-Myc nuclear immunopositivity (p = 0.018). In survival analysis, CIP2A failed to show any prognostic significance (p = 0.270, log-rank test).

METHODS

863 consecutive colorectal cancer patients treated at Helsinki University Central Hospital in 1983–2001 were collected with 752 scored successfully for CIP2A immunohistochemical expression from tumor tissue microarrays. Associations with clinicopathologic variables and molecular markers were explored by the chi-square test, and the Kaplan-Meier method served for survival analysis.

CONCLUSIONS

Overexpression of CIP2A in colorectal cancer patients may be an important step in colorectal carcinogenesis. Based on our findings, CIP2A shows no association with patient prognosis in colorectal cancer, but is associated with nuclear c-Myc.

Transcriptome data analysis for cell culture processes

In the past decade, DNA microarrays have fundamentally changed the way we study complex biological systems. By measuring the expression levels of thousands of transcripts, the paradigm of studying organisms has shifted from focusing on the local phenomena of a few genes to surveying the whole genome. DNA microarrays are used in a variety of ways, from simple comparisons between two samples to more intricate time-series studies. With the large number of genes being studied, the dimensionality of the problem is inevitably high. The analysis of microarray data thus requires specific approaches. In the case of time-series microarray studies, data analysis is further complicated by the correlation between successive time points in a series.In this review, we survey the methodologies used in the analysis of static and time-series microarray data, covering data pre-processing, identification of differentially expressed genes, profile pattern recognition, pathway analysis, and network reconstruction. When available, examples of their use in mammalian cell cultures are presented.