Prognostic significance of USP22 as an oncogene in papillary thyroid carcinoma

Ubiquitin-modifying enzymes in thyroid cancer：Mechanisms and functions

Thyroid cancer is the most common malignant tumor of the endocrine system, and evidence suggests that post-translational modifications (PTMs) and epigenetic alterations play an important role in its development. Recently, there has been increasing evidence linking dysregulation of ubiquitinating enzymes and deubiquitinases with thyroid cancer. This review aims to summarize our current understanding of the role of ubiquitination-modifying enzymes in thyroid cancer, including their regulation of oncogenic pathways and oncogenic proteins. The role of ubiquitination-modifying enzymes in thyroid cancer development and progression requires further study, which will provide new insights into thyroid cancer prevention, treatment and the development of novel agents.

Contribution of microRNA-30d to the prevention of the thyroid cancer occurrence and progression: mechanism and implications

Thyroid cancer is a major endocrine tumor and represents an emerging health problem worldwide. MicroRNAs (miRNAs) have been addressed to participate in the pathogenesis and progression of thyroid cancer. However, it remains largely unknown what functions miR-30d may exert on thyroid cancer. This study, herein, aimed to identify the functional significance and machinery of miR-30d in the progression of thyroid cancer. MiR-30b presented aberrant low expression and ubiquitin-specific protease 22 (USP22) exhibited aberrant high expression in thyroid cancer tissues and cells. The current study proposed the possible machinery that miR-30d could target and negatively regulate USP22. Additionally, USP22 could enhance the stability of SIRT1 by inducing deubiquitination which consequently contributed to FOXO3a deacetylation-induced PUMA repression. Responding to the gain- or loss-of-function of miR-30d and/or USP22, behaviors of thyroid cancer cells were altered. Accordingly, miR-30d inhibited proliferation and promoted apoptosis of thyroid cancer cells by suppressing USP22 through SIRT1/FOXO3a/PUMA axis. The effects of miR-30d and USP22-mediated SIRT1/FOXO3a/PUMA axis on thyroid tumorigenesis were finally validated in murine models. We ultimately confirmed the anti-proliferative and pro-apoptotic effect of miR-30d via suppressing USP22 through in vivo findings. Conclusively, our findings highlight that the occurrence and progression of thyroid cancer can be suppressed by miR-30d-mediated inhibition of USP22 via the SIRT1/FOXO3a/PUMA axis, which provides a attractive therapeutic target for thyroid cancer treatment.

Role of H2B mono-ubiquitination in the initiation and progression of cancer

Numerous epigenetic alterations are observed in cancer cells, and dysregulation of mono-ubiquitination of histone H2B (H2Bub1) has often been linked to tumorigenesis. H2Bub1 is a dynamic post-translational histone modification associated with transcriptional elongation and DNA damage response. Histone H2B monoubiquitination occurs in the site of lysine 120, written predominantly by E3 ubiquitin ligases RNF20/RNF40 and deubiquitinated by ubiquitin specific peptidase 22 (USP22). RNF20/40 is often altered in the primary tumors including colorectal cancer, breast cancer, ovarian cancer, prostate cancer, and lung cancer, and the loss of H2Bub1 is usually associated with poor prognosis in tumor patients. The purpose of this review is to summarize the current knowledge of H2Bub1 in transcription, DNA damage response and primary tumors. This review also provides novel options for exploiting the potential therapeutic target H2Bub1 in personalized cancer therapy.

Reduced USP22 Expression Impairs Mitotic Removal of H2B Monoubiquitination, Alters Chromatin Compaction and Induces Chromosome Instability That May Promote Oncogenesis

Chromosome instability (CIN) is an enabling feature of oncogenesis associated with poor patient outcomes, whose genetic determinants remain largely unknown. As mitotic chromatin compaction defects can compromise the accuracy of chromosome segregation into daughter cells and drive CIN, characterizing the molecular mechanisms ensuring accurate chromatin compaction may identify novel CIN genes. In vitro, histone H2B monoubiquitination at lysine 120 (H2Bub1) impairs chromatin compaction, while in vivo H2Bub1 is rapidly depleted from chromatin upon entry into mitosis, suggesting that H2Bub1 removal may be a pre-requisite for mitotic fidelity. The deubiquitinating enzyme USP22 catalyzes H2Bub1 removal in interphase and may also be required for H2Bub1 removal in early mitosis to maintain chromosome stability. In this study, we demonstrate that siRNA-mediated USP22 depletion increases H2Bub1 levels in early mitosis and induces CIN phenotypes associated with mitotic chromatin compaction defects revealed by super-resolution microscopy. Moreover, USP22-knockout models exhibit continuously changing chromosome complements over time. These data identify mitotic removal of H2Bub1 as a critical determinant of chromatin compaction and faithful chromosome segregation. We further demonstrate that USP22 is a CIN gene, indicating that USP22 deletions, which are frequent in many tumor types, may drive genetic heterogeneity and contribute to cancer pathogenesis.

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.

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.

Hypoxia-induced USP22-BMI1 axis promotes the stemness and malignancy of glioma stem cells via regulation of HIF-1α

AIMS

This study intends to investigate the mechanisms of ubiqutin-specific protease 22 (USP22)/B cell-specific Moloney murine leukemia virus integration site 1 (BMI1) on the biological phenotypes of glioma stem cells (GSCs) under hypoxia.

MAIN METHODS

Western blot, Cell Counting Kit-8, colony formation and flow cytometry assays were preformed to evaluate cells biological behaviors. Luciferase assay was utilized to identify the associations among USP22, HIF-1α and BMI1.

KEY FINDINGS

Silencing USP22 reduced the stemness and proliferation of GSCs, and increased its apoptosis in response to hypoxia. Whilst, overexpression of BMI1 reversed these phenomena. Whilst, a significant decrease in proliferation and stemness of GSCs caused by HIF-1α exhaustion were inversed by overexpression of USP22 or BMI1.

SIGNIFICANCE

Function of USP22-BMI1 on biological behaviors of GSCs was regulated by HIF-1α in response to hypoxia.

Deubiquitination in prostate cancer progression: role of USP22

Prostate cancer (PCa) is the leading cause of cancer death in men. With more therapeutic modalities available, the overall survival in PCa has increased significantly in recent years. Patients with relapses after advanced secondgeneration anti-androgen therapy however, often show poor disease prognosis. This group of patients often die from cancer-related complicacies. Multiple approaches have been taken to understand disease recurrence and to correlate the gene expression profile. In one such study, an 11-gene signature was identified to be associated with PCa recurrence and poor survival. Amongst them, a specific deubiquitinase called ubiquitin-specific peptidase 22 (USP22) was selectively and progressively overexpressed with PCa progression. Subsequently, it was shown to regulate androgen receptors and Myc, the two most important regulators of PCa progression. Furthermore, USP22 has been shown to be associated with the development of therapy resistant PCa. Inhibiting USP22 was also found to be therapeutically advantageous, especially in clinically challenging and advanced PCa. This review provides an update of USP22 related functions and challenges associated with PCa research and explains why targeting this axis is beneficial for PCa relapse cases.

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.

Deubiquitinating enzymes as cancer biomarkers: new therapeutic opportunities?

Cancer remains a life-threatening disease and accounts for the major mortality rates worldwide. The practice of using biomarkers for early detection, staging, and customized therapy may increase cancer patients’ survival. Deubiquitinating enzymes (DUBs) are a family of proteases that remove ubiquitin tags from proteins of interest undergoing proteasomal degradation. DUBs play several functional roles other than deubiquitination. One of the important roles of DUBs is regulation of tumor progression. Several reports have suggested that the DUB family members were highly-elevated in various cancer cells and tissues in different stages of cancer. These findings suggest that the DUBs could be used as drug targets in cancer therapeutics. In this review, we recapitulate the role of the DUB family members, including ubiquitin-specific protease, otubain protease, and important candidates from other family members. Our aim was to better understand the connection between DUB expression profiles and cancers to allow researchers to design inhibitors or gene therapies to improve diagnosis and prognosis of cancers.

Ubiquitin-specific protease 22 promotes the proliferation, migration and invasion of glioma cells

Ubiquitin-specific protease 22 (USP22), as one of the 11 death-from-cancer signature genes, presented high expression in a variety of tumors. Previous studies showed that USP22 played a significant role in cell-cycle, oncogenesis, clinicopathology and survival. Our studies have presented USP22 was over-expressed in glioma tissue and the patients with high expression of USP22 had a poor survival than that with low expression of USP22. However, the concrete effect of USP22 on biological behavior in glioma cells has been rarely reported. The study aimed to clear the effect of USP22 on cell proliferation, migration and invasion in glioma. Using siRNA, USP22 was knocked down in U251 and U87 glioma cells and successful transfection effect was validated. Cell proliferation, migration and invasion were observed by the methods of EdU, Wound healing and Transwell assay, separately. At the same time, the expression of MMP2 was detected by Gelatin zymography after transfecting siRNAs. After the knockdown of USP22 by siRNA, the abilities of glioma cell proliferation, migration and invasion were decreased, accompanying, the expression of MMP2 was also decreased. We drew a conclusion that USP22 could increase the abilities of proliferation, migration and invasion of glioma cells, and promote the growth and development of glioma.

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.

Microtubule-Associated Protein 4 Is a Prognostic Factor and Promotes Tumor Progression in Lung Adenocarcinoma

Microtubule-associated protein 4 (MAP4) plays an important role in microtubule assembly and stabilization. The purpose of this study was to investigate the level of expression of MAP4 in lung adenocarcinoma (LADC) samples and to evaluate its prognostic value and the influence on cancer progression in LADC patients. The expression of MAP4 protein was analyzed using immunohistochemistry. The clinical significance and the prognostic significance of MAP4 expression were assessed by Kaplan-Meier analysis and Cox regression analysis. The roles of MAP4 in the migration and invasion of LADC cells were detected by wound-healing assays and transwell assays, respectively. We found the expression levels of MAP4 protein in LADC tissues to be significantly higher than those in noncancerous tissues. MAP4 expression was significantly correlated with differentiation, pathological T stage, and TNM stage. Kaplan-Meier survival analysis indicated that patients with high MAP4 expression had significantly poorer overall survival (OS). Cox regression analysis revealed that MAP4 expression level was an independent prognostic factor for OS. Functionally, in vitro studies showed that MAP4 knockdown efficiently suppressed the migration and invasion of LADC cells. Our data indicated that MAP4 protein may represent a novel prognostic biomarker and a potential therapeutic target for LADC.

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.

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.

Ubiquitin specific peptidase 5 mediates Histidine-rich protein Hpn induced cell apoptosis in hepatocellular carcinoma through P14-P53 signaling

Hpn is a small histidine-rich cytoplasmic protein from Helicobacter pylori and has been recognized as a high-risk factor for several cancers including gastric cancer, colorectal cancer, and MALT lymphoma. However, the relationship between Hpn and cancers remains elusive. In this study, we discovered that Hpn protein effectively suppressed cell growth and induced apoptosis in hepatocellular carcinoma (HCC). A two-dimensional gel electrophoresis and mass spectrometry-based comparative proteomics was performed to find the molecular targets of Hpn in HCC cells. It was identified that twelve proteins were differentially expressed, with USP5 being one of the most significantly downregulated protein. The P14^ARF -P53 signaling was activated by USP5 knockdown in HCC cells. Furthermore, USP5 overexpression significantly rescued the suppressive effect of Hpn on the viability of HCC cells. In conclusion, our study suggests that Hpn plays apoptosis-inducing roles through suppressing USP5 expression and activating the P14^ARF -P53 signaling. Therefore, Hpn may be a potential candidate for developing novel anti-HCC drugs.

Overexpression miR-211-5p hinders the proliferation, migration, and invasion of thyroid tumor cells by downregulating SOX11

PURPOSE

This study was aimed to investigate the relationship between miR-211-5p and SOX11, and the effects of their interaction on the proliferation, viability, and invasion of human thyroid cancer (TC) cells.

METHODS

We used quantitative real-time PCR (qRT-PCR) to determine the expression of miR-211-5p and SOX11mRNA in the thyroid tumorous and the adjacent tissues. The target relationship between miR-211-5p and SOX11 was confirmed using dual luciferase reporter gene assay. Flow cytometry, colony formation assay, Transwell assay, and MTT assay were performed to determine the cell-cycle progression, cell apoptosis, proliferation and invasion, respectively. In addition, the tumor formation assay in nude mice was done to assess the effect of miR-211-5p on TC development in vivo.

RESULTS

MiR-211-5p was underexpressed, whereas SOX11 was overexpressed in TC. The overexpression of miR-211-5p inhibited the expression of SOX11. The cell cycle was arrested and the proliferation as well as invasiveness was suppressed by exogenous miR-211-5p in TC cell line. The antitumor role of miR-211-5p was proved by the animal experiment.

CONCLUSION

MiR-211-5p affected the viability, proliferation and invasion of TC by negatively regulating SOX11 expression.

Downregulation of USP32 inhibits cell proliferation, migration and invasion in human small cell lung cancer

OBJECTIVES

Ubiquitin specific protease 32 (USP32) is a highly conserved but uncharacterized gene, which has been reported to be associated with growth of breast cancer cells. However, the role of USP32 in human small cell lung cancer (SCLC) has not been uncovered. The aim of this study was to investigate and evaluate the clinical significance of USP32 in patients with SCLC.

MATERIALS AND METHODS

Expression of USP32 was firstly investigated using public online data sets and then determined in SCLC tissues and cell lines using quantitative real-time PCR, Western blotting and immunohistochemical staining. SCLC cells were transfected with a small-interfering RNA targeting USP32 mRNA and analysed for cell viability, proliferation ability, cell cycle distribution, apoptosis and invasion.

RESULTS

USP32 was found to be overexpressed in SCLC tissues compared with normal tissues. High USP32 expression was significantly correlated with disease stage and invasion. In vitro experiments demonstrated that silencing of USP32 caused a significant decrease in the proliferation and migration rate of cells. Furthermore, USP32 silencing arrested cell cycle progression at G0/G1 phase via decreasing CDK4/Cyclin D1 complex and elevating p21. In addition, downregulation of USP32 significantly induced cell apoptosis by activating cleaved caspase-3 and cleaved PARP, as well as inhibiting cell invasiveness via altering epithelial mesenchymal transition expression.

CONCLUSIONS

Our results suggest for the first time that USP32 is important for SCLC progression and might be a potential target for molecular therapy of SCLC.

Usp5 functions as an oncogene for stimulating tumorigenesis in hepatocellular carcinoma

As deubiquitinases, several ubiquitin specific protease members have been reported to mediate tumorigenesis. Although ubiquitin specific protease 5 (Usp5) was previously demonstrated to suppress p53 transcriptional activity and DNA repair, its role in carcinogenesis remains elusive. In this study, we sought to define a novel role of Usp5 in tumorigenesis. It was found that Usp5 was significantly upregulated in hepatocellular carcinoma (HCC) cells and most clinical specimens. Further functional investigation also showed that Usp5 knockdown suppressed cell proliferation, migration, drug resistance and induced apoptosis; on the other hand, Usp5 overexpression promoted colony formation, migration, drug resistance and tumorigenesis. Additionally, the inactivated p14^ARF-p53 signaling was observed in Usp5 overexpressed HCC cells, while this signaling was activated by Usp5 knockdown. Therefore, our data demonstrated that Usp5 contributed to hepatocarcinogenesis by acting as an oncogene, which provides new insights into the pathogenesis of HCC and explores a promising molecular target for HCC diagnosis and therapy.

Targeting ubiquitin-specific protease 22 suppresses growth and metastasis of anaplastic thyroid carcinoma

Ubiquitin-specific protease 22 (USP22) aberrance has been implicated in several malignancies; however, whether USP22 plays a role in anaplastic thyroid carcinoma (ATC) remains unclear. Here, we report that USP22 expression is highly elevated in ATC tissues, which positively correlated with tumor size, extracapsular invasion, clinical stages, and poor prognosis of ATC patients. In vitro assays showed that USP22 depletion suppressed ATC cell survival and proliferation by decreasing Rb phosphorylation and cyclin D2, inactivating Akt, and simultaneously upregulating Rb; USP22 silencing restrained cell migration and invasion by inhibiting epithelial-mesenchymal transition; USP22 knockdown promoted mitochondrion- mediated and caspase-dependent apoptosis by upregulating Bax and Bid and promoting caspase-3 activation. Consistent with in vitro findings, downregulation of USP22 in ATC cells impeded tumor growth and lung metastasis in vivo. These results raise the applicability for USP22 as a useful predictor of ATC prognosis and a potential therapeutic target for ATC.

Deubiquitinases in cancer

Deubiquitinases are deubiquitinating enzymes (DUBs), which remove ubiquitin from proteins, thus regulating their proteasomal degradation, localization and activity. Here, we discuss DUBs as anti-cancer drug targets.

Regulation of MET-mediated proliferation of thyroid carcinoma cells by miR-449b

Thyroid carcinoma (TC) is a lethal cancer worldwide, whereas its carcinogenesis is not fully understood. Although growing evidence has demonstrated that dysregulation of microRNAs (miRNAs) contributes to the development of various cancers, the role of miRNAs in the pathogenesis of TC is poorly characterized. Here, we analyzed the levels of miR-449b in TC tissues and detected significantly lower miR-449b levels in TC tissues. Moreover, the low miR-449b levels were associated with poor survival. We then overexpressed miR-449b by miRNA mimic transfection and inhibited miR-449b by miRNA antisense transfection. Cell growth was analyzed by CCK-8 assay and MTT assay, and apoptosis and cell proliferation were analyzed by flow cytometry. Overexpression of miR-449b significantly inhibited cell growth, while depletion of miR-449b increased cell growth. Moreover, the effects of miR-449b on cell growth were through modulation of cell proliferation rather than through modulation of cell apoptosis. Targeted genes were predicted by a bioinformatics algorithm and confirmed by a dual luciferase reporter assay, showing that miR-449b binds to the 3'-UTR of MET (hepatocyte growth factor receptor) mRNA, to inhibit its expression in TC cells. MET levels were regulated by miR-449b in TT cells. Together, we show that reduced miR-449b levels in TT tissues may promote TC growth, through MET-mediated cell proliferation.

Thyroid carcinoma cells produce PLGF to enhance metastasis

Cancer neovascularization is essential for metastasis of thyroid carcinoma. However, the underlying molecular mechanisms are ill-defined. Recently, placental growth factor (PLGF) has been shown to play critical roles in the pathological angiogenesis through regulating matrix metalloproteinases (MMPs); here, we were prompted to examine the role of PLGF in the metastasis of thyroid carcinoma. We found that the PLGF and MMP9 levels strongly correlated in the thyroid carcinoma specimen. Higher PLGF and MMP9 levels were detected in the thyroid carcinoma with metastasis. Using a human thyroid carcinoma cell line, TT, we found that overexpression of PLGF in TT cells increased expression of MMP9, while inhibition of PLGF in TT cells decreased expression of MMP9. However, modification of MMP9 levels in TT cells did not affect PLGF levels, suggesting that PLGF may regulate MMP9 in thyroid carcinoma cells. Moreover, application of a specific MAPK p42/p44 inhibitor, but not the application of a specific MAPK p38 inhibitor or specific Akt or JNK inhibitors, substantially abolished the effect of PLGF on MMP9 activation, suggesting that PLGF may increase expression of MMP9 via p42/p44 signaling pathway. Together, these data suggest that antagonizing PLGF in thyroid carcinoma cells may be a promising therapy to suppress cancer metastasis.

"Upstream Analysis": An Integrated Promoter-Pathway Analysis Approach to Causal Interpretation of Microarray Data

A strategy is presented that allows a causal analysis of co-expressed genes, which may be subject to common regulatory influences. A state-of-the-art promoter analysis for potential transcription factor (TF) binding sites in combination with a knowledge-based analysis of the upstream pathway that control the activity of these TFs is shown to lead to hypothetical master regulators. This strategy was implemented as a workflow in a comprehensive bioinformatic software platform. We applied this workflow to gene sets that were identified by a novel triclustering algorithm in naphthalene-induced gene expression signatures of murine liver and lung tissue. As a result, tissue-specific master regulators were identified that are known to be linked with tumorigenic and apoptotic processes. To our knowledge, this is the first time that genes of expression triclusters were used to identify upstream regulators.

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

OBJECTIVES

Our previous study showed that USP22 as an oncogene may mediate cancer development and progression in NSCLC, but the underlying molecular mechanism remains uncharacterized. Epithelial-mesenchymal transition (EMT) has been reported to play an important role in migration and invasion of the tumor cells. Thus, this study aims to determine the clinical significance and the possible roles of USP22 in EMT and progression of lung adenocarcinoma.

METHODS

Immunohistochemistry was used to determine the expression of USP22 in clinical samples. The clinical correlations and prognostic significance of the aberrantly expressed proteins were evaluated by statistical analysis. Moreover, we evaluated whether USP22 could induce EMT in cultured lung cancer cells.

RESULTS

The USP22 expression was positive in 76.03% of specimens and was correlated with advanced clinicopathologic classifications (differentiation, T and AJCC stages) and TGF-β1 expression (p=0.008). Multivariate Cox regression analysis revealed that USP22 expression level was an independent prognostic factor for both overall survival and disease-free survival (HR, 2.060; p=0.013 and HR, 1.993; p=0.016). In vitro study revealed that USP22 can regulate proliferation and invasive properties, and induce EMT of lung adenocarcinoma cells. Moreover, USP22 may up-regulate TGF-β1 expression.

CONCLUSIONS

Our data indicated that USP22 may promote lung adenocarcinoma cell invasion by the induction of EMT.

Ubiquitin-specific peptidase 22 overexpression may promote cancer progression and poor prognosis in human gastric carcinoma

Ubiquitin-specific peptidase 22 (USP22) was recently identified as a new tumor cell marker, and previous studies demonstrated its expression in a variety of tumors and its correlation with tumor progression. Because tumor progression plays an important role in cancer, researchers are paying more attention to the correlation between USP22 expression and metastatic potential, resistance to chemotherapy, and patient prognosis. This study showed that USP22 is highly expressed in gastric cancer tissues, and significant differences in USP22 expression (P < 0.01) were identified between different types of gastric cancer (the highest expression was found in poorly differentiated adenocarcinomas). In addition USP22 expression was found to be correlated with the promotion of cancer evolution, tumor invasion, and lymph node metastasis. The C-myc protein was also shown to have synergistic effects with USP22 in gastric cancer tissue. On the basis of the results, USP22 expression may play an important role in gastric carcinoma tissue, particularly in precancerous lesions during the gastric cancer evolution process.

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.

Histone H2B monoubiquitination: roles to play in human malignancy

Ubiquitination has traditionally been viewed in the context of polyubiquitination that is essential for marking proteins for degradation via the proteasome. Recent discoveries have shed light on key cellular roles for monoubiquitination, including as a post-translational modification (PTM) of histones such as histone H2B. Monoubiquitination plays a significant role as one of the largest histone PTMs, alongside smaller, better-studied modifications such as methylation, acetylation and phosphorylation. Monoubiquitination of histone H2B at lysine 120 (H2Bub1) has been shown to have key roles in transcription, the DNA damage response and stem cell differentiation. The H2Bub1 enzymatic cascade involves E3 RING finger ubiquitin ligases, with the main E3 generally accepted to be the RNF20-RNF40 complex, and deubiquitinases including ubiquitin-specific protease 7 (USP7), USP22 and USP44. H2Bub1 has been shown to physically disrupt chromatin strands, fostering a more open chromatin structure accessible to transcription factors and DNA repair proteins. It also acts as a recruiting signal, actively attracting proteins with roles in transcription and DNA damage. H2Bub1 also appears to play central roles in histone cross-talk, influencing methylation events on histone H3, including H3K4 and H3K79. Most significantly, global levels of H2Bub1 are low to absent in advanced cancers including breast, colorectal, lung and parathyroid, marking H2Bub1 and the enzymes that regulate it as key molecules of interest as possible new therapeutic targets for the treatment of cancer. This review offers an overview of current knowledge regarding H2Bub1 and highlights links between dysregulation of H2Bub1-associated enzymes, stem cells and malignancy.

USP22 promotes NSCLC tumorigenesis via MDMX up-regulation and subsequent p53 inhibition

Increasing evidence suggests that ubiquitin-specific protease 22 (USP22) has great clinicopathologic significance in oncology. In this study, we investigated the role of USP22 in human NSCLC tumorigenesis along with the underlying mechanisms of action. First, we determined the expression of USP22 in human NSCLC, as well as normal tissues and cell lines. We then studied the effects of USP22 silencing by shRNA on NSCLC cell growth in vitro and tumorigenesis in vivo, along with the effect on the p53 pathway. We found that USP22 is overexpressed in human NSCLC tissues and cell lines. USP22 silencing by shRNA inhibits proliferation, induces apoptosis and arrests cells at the G0/G1 phases in NSCLC cells and curbs human NSCLC tumor growth in a mouse xenograft model. Additionally, USP22 silencing downregulates MDMX protein expression and activates the p53 pathway. Our co-immunoprecipitation analysis shows that USP22 interacts with MDMX in NSCLC cells. Furthermore, MDMX silencing leads to growth arrest and apoptosis in NSCLC cells, and over-expression of MDMX reverses the USP22 silencing-induced effects. Taken together, our results suggest that USP22 promotes NSCLC tumorigenesis in vitro and in vivo through MDMX upregulation and subsequent p53 inhibition. USP22 may represent a novel target for NSCLC treatment.

Emerging potential of therapeutic targeting of ubiquitin-specific proteases in the treatment of cancer

The ubiquitin-proteasome system (UPS) has emerged as a therapeutic focus and target for the treatment of cancer. The most clinically successful UPS-active agents (bortezomib and lenalidomide) are limited in application to hematologic malignancies, with only marginal efficacy in solid tumors. Inhibition of specific ubiquitin E3 ligases has also emerged as a valid therapeutic strategy, and many targets are currently being investigated. Another emerging and promising approach in regulation of the UPS involves targeting deubiquitinases (DUB). The DUBs comprise a relatively small group of proteins, most with cysteine protease activity that target several key proteins involved in regulation of tumorigenesis, apoptosis, senescence, and autophagy. Through their multiple contacts with ubiquitinated protein substrates involved in these pathways, DUBs provide an untapped means of modulating many important regulatory proteins that support oncogenic transformation and progression. Ubiquitin-specific proteases (USP) are one class of DUBs that have drawn special attention as cancer targets, as many are differentially expressed or activated in tumors or their microenvironment, making them ideal candidates for drug development. This review attempts to summarize the USPs implicated in different cancers, the current status of USP inhibitor-mediated pharmacologic intervention, and future prospects for USP inhibitors to treat diverse cancers.

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 peptidase 22, a histone deubiquitinating enzyme, is a novel poor prognostic factor for salivary adenoid cystic carcinoma

Salivary Adenoid Cystic Carcinoma (SACC) is characterized by a high rate of local recurrence and infiltration, strong invasion to peripheral nerves or late distant metastasis. Our aim was to investigate the expression of Ubiquitin-specific protease 22 (USP22) in SACC patients and its possible relationship to the outcome of the disease. A total of 135 SACC tissues and adjacent non-cancerous tissues which were diagnosed between 2002 and 2007 were enrolled in this study. Immunohistochemistry was used to compare the expression pattern of USP22 in SACC and adjacent non-cancerous groups, and the prognostic significance was assessed by Kaplan-Meier analysis and Cox proportional hazards regression in SACC patients. The rate of high expression of USP22 was significantly higher in SACC group than that in adjacent non-cancerous group. High expression of USP22 was significantly correlated with histological subtype, lymph node metastasis, grade, Ki-67 and SOX2 expression. Furthermore, USP22 acts as an oncogene by regulation the BMI-1 pathway and c-Myc pathway. SACC patients with high USP22 expression showed the poorer overall survival (OS) and disease-free survival (DFS) than those patients with low USP22 expression. In multivariate analysis, only lymph node metastasis and USP22 expression were the independent prognostic factors for OS and DFS in SACC. Our study provides evidence that USP22 expression is an independent prognostic factor for SACC patients.

Prognostic significance of USP10 as a tumor-associated marker in gastric carcinoma

Ubiquitin-specific protease 10 (USP10), a novel deubiquitinating enzyme, had been associated with growth of tumor cell. However, the role of USP10 in gastric cancer carcinogenesis had not been elucidated yet. The aim of this study was to investigate the expression level of USP10 in gastric carcinoma (GC) tissues and cell lines, then to evaluate the clinical significance of USP10 in GC patients. USP10, E-cadherin, Ki67 and p53 expressions were detected in 365 GC and 40 non-cancerous mucosa tissues by immunohistochemistry. Western blot for USP10 was performed on additional fresh GC tissues and GC cell lines. The expression level of USP10 in GC tissues was proved lower than that in non-cancerous mucosa tissues (p < 0.05). It was also lower in GC cell lines (AGS, BGC-823 and MKN45 cells) than that in gastric epithelial immortalized cell line (GES-1). Clinicopathological analysis showed that USP10 expression was negatively correlated with gastric wall invasion (p = 0.009), nodal metastasis (p = 0.002), and TNM stage (p = 0.000). In contrast, a positively correlation between the expression of USP10 and E-cadherin was found (p < 0.05), but there was no relationship proved between Ki67, p53 and USP10 (p > 0.05). On the Kaplan-Meier survival curves, we found poor prognosis in GC patients was associated with negative USP10 expression (p < 0.05). Moreover, USP10 expression was an independent prognostic factor for the overall survival in multivariate analysis. Our findings suggested that USP10 was an independent predictor of prognosis of GC patients.

USP22 regulates oncogenic signaling pathways to drive lethal cancer progression

Increasing evidence links deregulation of the ubiquitin-specific proteases 22 (USP22) deubitiquitylase to cancer development and progression in a select group of tumor types, but its specificity and underlying mechanisms of action are not well defined. Here we show that USP22 is a critical promoter of lethal tumor phenotypes that acts by modulating nuclear receptor and oncogenic signaling. In multiple xenograft models of human cancer, modeling of tumor-associated USP22 deregulation demonstrated that USP22 controls androgen receptor accumulation and signaling, and that it enhances expression of critical target genes coregulated by androgen receptor and MYC. USP22 not only reprogrammed androgen receptor function, but was sufficient to induce the transition to therapeutic resistance. Notably, in vivo depletion experiments revealed that USP22 is critical to maintain phenotypes associated with end-stage disease. This was a significant finding given clinical evidence that USP22 is highly deregulated in tumors, which have achieved therapeutic resistance. Taken together, our findings define USP22 as a critical effector of tumor progression, which drives lethal phenotypes, rationalizing this enzyme as an appealing therapeutic target to treat advanced disease.