Ubiquitin-specific protease 1 overexpression indicates poor prognosis and promotes proliferation, migration, and invasion of gastric cancer cells.

Ubiquitin-specific protease 1 (USP1) has been documented to involved in the occurrence and development of different kinds of malignancies, containing breast cancer, glioma and prostatic cancer. However, the role of USP1 in gastric cancer (GC) is still obscure. In method, gene expression profiling interactive analysis and Kaplan-Meier Plotter databases were applied to analyze the prognostic value of USP1 in human cancers. The expression of USP1 was evaluated by quantitative reverse transcription polymerase chain reaction assay and western blotting. Cell proliferation, migration, and invasion abilities were detected to determin the role of USP1 in the tumorigenesis of GC. As a result, USP1 was upregulated in GC samples relative to its paired normal samples. USP1 was a valuable diagnostic marker for GC, and its overexpression indicated the poor overall survival time of patients with GC. More importantly, USP1 levels were increased in GC cells and its silencing restrained the proliferation, migration, invasion and epithelial-to-mesenchymal transition (EMT) of GC cells. In Conclusion, USP1 was upregulated in GC, and might be a valuable diagnostic and prognostic marker for GC. Moreover, USP1 silencing hindered the proliferation, migration, invasion, and EMT of GC cells, revealing the oncogenic role of USP1 in GC progression.

USP1-WDR48 deubiquitinase complex enhances TGF-ß induced epithelial-mesenchymal transition of TNBC cells via stabilizing TAK1.

Triple-negative breast cancer (TNBC) is the most aggressive histological subtype of breast cancer and is characterized by poor outcomes and a lack of specific-targeted therapies. Transforming growth factor-ß (TGF-ß) acts as the key cytokine in the epithelial-mesenchymal transition (EMT) and the metastasis of TNBC. However, the regulatory mechanisms of the TGF-ß signaling pathway remain largely unknown. In this study, we identified that the USP1/WDR48 complex could effectively enhance TGF-ß-mediated EMT and migration of TNBC cells. Furthermore, lower phosphorylation of Smad2/3, Erk, Jnk, and p38 was noted on the suppression of the expression of endogenous USP1 or WDR48. Moreover, the USP1-WDR48 complex was found to downregulate the polyubiquitination of TAK1 and mediate its in vitro stability. Therefore, our findings have shed a light on the novel role of the USP1/WDR48 complex in promoting TGF-ß-induced EMT and migration in TNBC via in vitro stabilization of TAK1.

Cav3.2 overexpression in L4 dorsal root ganglion neurons after L5 spinal nerve cutting involves Egr-1, USP5 and HMGB1 in rats: An emerging signaling pathway for neuropathic pain.

Overexpression of Cav3.2 T-type Ca2+ channels in L4 dorsal root ganglion (DRG) participates in neuropathic pain after L5 spinal nerve cutting (L5SNC) in rats. The L5SNC-induced neuropathic pain also involves high mobility group box 1 (HMGB1), a damage-associated molecular pattern protein, and its target, the receptor for advanced glycation end-products (RAGE). We thus studied the molecular mechanisms for the L5SNC-induced Cav3.2 overexpression as well as neuropathic pain in rats by focusing on; 1) possible involvement of early growth response 1 (Egr-1), known to regulate transcriptional expression of Cav3.2, and ubiquitin-specific protease 5 (USP5) that protects Cav3.2 from proteasomal degradation, and 2) possible role of HMGB1/RAGE as an upstream signal. Protein levels of Cav3.2 as well as Egr-1 in L4 DRG significantly increased in the early (day 6) and persistent (day 14) phases of neuropathy after L5SNC, while USP5 protein in L4 DRG did not increase on day 6, but day 14. An anti-HMGB1-neutralizing antibody or a low molecular weight heparin, a RAGE antagonist, prevented the development of neuropathic pain and upregulation of Egr-1 and Cav3.2 in L4 DRG after L5SNC. L5SNC increased macrophages accumulating in the sciatic nerves, and the cytoplasm/nuclear ratio of immunoreactive HMGB1 in those macrophages. Our findings suggest that L5SNC-induced Cav3.2 overexpression in L4 DRG and neuropathic pain involves Egr-1 upregulation downstream of the macrophage-derived HMGB1/RAGE pathway, and that the delayed upregulation of USP5 might contribute to the persistent Cav3.2 overexpression and neuropathy.

The Effects of the Transforming Growth Factor-ß1 (TGF-ß1) Signaling Pathway on Cell Proliferation and Cell Migration are Mediated by Ubiquitin Specific Protease 4 (USP4) in Hypertrophic Scar Tissue and Primary Fibroblast Cultures.

BACKGROUND Hypertrophic scar results from an abnormal repair response to trauma in the skin and involves fibroblasts proliferation with increased collagen deposition. Transforming growth factor-ß1 (TGF-ß1) and TGF-ß receptor type I (TGF-ßR1) are involved in tissue repair and are increased by ubiquitin-specific protease 4 (USP4). This study aimed to investigate the effects of TGF-ßR1 and USP4 in human tissue samples of hypertrophic scar and on cell proliferation and cell migration in primary fibroblast cultures in vitro. MATERIAL AND METHODS Skin excision tissue samples with adjacent normal skin were obtained from 15 patients with hypertrophic scar, which provided tissue sections and primary fibroblast culture for analysis. Immunohistochemistry detected the expression of USP4 and TGF-ßR1 in tissue sections. MicroRNA (miRNAs) expression levels were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Western blot was performed to measure protein expression levels. Cultured skin fibroblasts were investigated using immunofluorescence staining. Fibroblast proliferation, apoptosis, and migration were measured with the Cell Counting Kit-8 (CCK-8) assay, flow cytometry, and a wound-healing assay, respectively. RESULTS The expression of USP4 and TGF-ßR1 in hypertrophic scar were increased compared with normal skin. Fibroblasts cultured from hypertrophic scar tissue showed increased expression of of USP4 and TGF-ßR1. Fibroblast transfection with USP4 short-interfering RNA (siRNA) resulted in reduced fibroblast proliferation and migration, and increased apoptosis. Downregulation of USP4 inhibited the expression of TGF-ßR1 protein and increased the expression levels of Smad7 protein. CONCLUSIONS USP4 regulated the proliferation, migration, and apoptosis of hypertrophic scar fibroblasts by regulating the TGF-ß1 signaling pathway.

De-regulated STAT5A/miR-202-5p/USP15/Caspase-6 regulatory axis suppresses CML cell apoptosis and contributes to Imatinib resistance.

BACKGROUND: STAT5 plays an important role in the transformation of hematopoietic cells by BCR-ABL. However, the downstream target genes activated by STAT5 in chronic myeloid leukemia (CML) cells remain largely unclear. Here, we investigated the mechanistic functional relationship between STAT5A-regulated microRNA and CML cell apoptosis. METHODS: The expression of USP15, Caspase-6, STAT5A-regulated miR-202-5p and STAT5A was detected by qRT-PCR and Western blotting in CML cell lines and PBMCs of CML patients. Cell apoptosis was evaluated by flow cytometry. Both gain- and loss-of-function experiments were used to investigate the roles of USP15, miR-202-5p and STAT5A in CML. Luciferase reporter assay detected the effect of miR-202-5p on USP15 expression. Xenograft animal model was used to test the effect of anti-miR-202-5p and pimozide on K562 cell xenograft growth. RESULTS: USP15 expression was significantly downregulated in CML cell lines and PBMCs of CML patients. Depletion of USP15 increased, whereas overexpression of USP15 reduced the resistance of CML cells to Imatinib. Further, decreased deubiquitinating activity of USP15 by USP15 downregulation led to reduced caspase-6 level, thus attenuating CML cell apoptosis. Mechanistically, miR-202-5p was upregulated in K562G cells and negatively regulated USP15 expression by directly targeting USP15 3'-UTR. Correspondingly, upregulation of miR-202-5p enhanced the resistance of CML cells to Imatinib by inhibiting cell apoptosis. Importantly, STAT5A was upregulated in CML cells and directly activated miR-202-5p transcription by binding to the pre-miR-202 promoter. Pimozide induced CML cell apoptosis and significantly reduced K562 cell xenograft growth in vivo by blocking STAT5A/miR-202-5p/USP15/Caspase-6 regulatory axis. CONCLUSIONS: we provide the first evidence that de-regulated STAT5A/miR-202-5p/USP15/Caspase-6 regulatory axis suppresses the apoptosis of CML cells, targeting this pathway might be a promising therapeutic approach for the treatment of CML.

Ubiquitin-specific peptidase 39 regulates the process of proliferation and migration of human ovarian cancer via p53/p21 pathway and EMT.

Ovarian cancer is one of the most lethal gynecological cancers; owning to its late detection and chemoresistance, understanding the pathogenesis of this malignant tumor is much critical. Previous studies have reported that ubiquitin-specific peptidase 39 (USP39) is generally overexpressed in a variety of cancers, including hepatocellular carcinoma, gastric cancer and so forth. Furthermore, USP39 is proved to be associated with the proliferation of malignant tumors. However, the function and mechanism of USP39 in ovarian cancer have not been elucidated. In the present study, we observed that USP39 was frequently overexpressed in human ovarian cancer and was highly correlated with TNM stage. Suppression of USP39 markedly inhibited the growth and migration of ovarian cancer cell lines HO-8910 and SKOV3 and induced cell cycle G2/M arrest. Moreover, knockdown of USP39 inhibited ovarian tumor growth in a xenograft model. In addition, our findings indicated that cell cycle arrest induced by USP39 knockdown might be involved in p53/p21 signaling pathway. Furthermore, we found that the depletion of USP39 inhibited the migration of ovarian cancer cells via blocking epithelial-mesenchymal transition. Taken together, these results suggest that USP39 may play vital roles in the genesis and progression and may serve as a potential biomarker for diagnosis and therapeutic target of ovarian cancer.

A four-mRNA model to improve the prediction of breast cancer prognosis.

BACKGROUND: Breast cancer (BRCA) is the most prevalent cancer that threatens female health. A growing body of evidence has demonstrated the non-negligible effects of messenger RNAs (mRNAs) on biological processes involved in cancers; however, there is no definite conclusion regarding the role of mRNAs in predicting the prognosis of BRCA patients. MATERIALS AND METHODS: We systematically screened the mRNA expression landscape and clinical data of samples from the Cancer Genome Atlas (TCGA). Univariate Cox analysis and robust likelihood-based survival analysis were conducted to identify key mRNAs associated with BRCA. Furthermore, risk scores based on multivariate Cox analysis divided the training set into high-risk and low-risk groups. ROC analysis determined the optimal cut-off point for patient classification of risk levels. The prognostic model was additionally validated in the testing set and complete dataset. Finally, we plotted the survival curves for the mRNAs used in our model. RESULTS: We obtained the original expression data of 13,617 mRNAs from a total of 1088 samples. After comprehensive survival analysis, the four-mRNA (ACSL1, OTUD3, PKD1L2, and WISP1) prognosis risk assessment model was constructed. Furthermore, the area under cure (AUC) was 0.834, indicating that the model was meaningful and reasonable. In each dataset, analysis based on the four-mRNA signature risk score indicated that the survival status of the group with high risk score was worse than that of the group with low risk scores. Patients with strong mRNA expression of OTUD3, PKD1L2, and WISP1 tended to have good prognosis, whereas patients with high ACSL1 expression tended to have poor prognosis. CONCLUSION: In summary, we constructed a four-mRNA prognosis risk assessment model for BRCA. The newly developed model offers more possibilities for assessing prognosis and guiding the selection of better treatment strategies for BRCA.

USP39 promotes ovarian cancer malignant phenotypes and carboplatin chemoresistance.

Ubiquitin­specific protease 39 (USP39), as one of the deubiquitinating enzymes (DUBs), exhibits aberrant an expression and has oncogenic functions in several types of cancer. However, the function and underlying molecular mechanisms of action of USP39 in ovarian cancer remain largely undetermined. The present study thus aimed to investigate whether USP39 is a promising tumor­associated gene and whether it could be a viable target for overcoming chemotherapeutic resistance in ovarian cancer. The present study identified that USP39 was highly expressed in ovarian cancer samples with carboplatin resistance. A series of functional assays revealed that the knockdown of USP39 in ES2 and SKOV3 cells significantly decreased cell proliferation, induced cell cycle arrest at the G2/M phase and impaired the cell colony formation ability. USP39 deficiency enhanced the carboplatin­induced apoptosis of the SKOV3 cells via the activation of poly­ADP ribose polymerase and caspase­3. USP39 knockdown led to the inhibition of cell migration and invasion. The opposite effects were observed when USP39 was overexpressed in the ES2 and SKOV3 cells. In vivo animal models revealed that the subcutaneous transplantation and intraperitoneal injection of USP39­overexpressing ES2 cells increased tumor burden with or without treatment with carboplatin. However, the knockdown of USP39 suppressed SKOV3 cell growth in vivo. Mechanistic analyses also demonstrated that USP39 induced the phosphorylation of extracellular signal­regulated kinase and AKT and increased the expression of epidermal growth factor receptor and cyclin B1. Collectively, the findings of this study suggest that USP39 may paly a vital role in regulating ovarian cancer malignant phenotypes and carboplatin resistance. Therefore, USP39 may prove to be a promising therapeutic target for patients with ovarian cancer.

FAM175B promotes apoptosis by inhibiting ATF4 ubiquitination in esophageal squamous cell carcinoma.

FAM175B is a reported regulator of p53 and suppresses tumorigenesis in numerous types of cancer, but very little is known about its function in esophageal squamous cell carcinomas (ESCCs), almost 70% of which exhibit mutations in p53. Here, we report that FAM175B expression is downregulated in high-grade intraepithelial neoplasia (t = 2.44, P = 0.031) and ESCC (t = 5.664, P < 0.001) tissues relative to that in adjacent normal esophageal tissues. Exogenous expression of FAM175B in ESCC cells resulted in a decrease in proliferation rate, inhibition of colony formation, and an increase in apoptosis rate. Knockdown of FAM175B produced the opposite results. Furthermore, confocal microscopy and coimmunoprecipitation assay showed that Activating transcription factor 4 (ATF4) colocalized and interacted with FAM175B. Ubiquitination assays revealed that FAM175B inhibited ubiquitin-dependent ATF4 degradation and elevated ATF4 protein level. Finally, luciferase reporter experiments further clarified that FAM175B promoted CHOP expression in an ATF4-dependent manner. Accordingly, the proapoptotic activity of FAM175B was significantly rescued by treatment with si-ATF4 and the CHOP inhibitor 4-PBA. In summary, FAM175B inhibited ATF4 ubiquitination and promoted ESCC cell apoptosis in a p53-independent manner. FAM175B expression loss may be an early diagnostic biomarker in ESCC patients.

YAP1-Mediated Suppression of USP31 Enhances NFκB Activity to Promote Sarcomagenesis.

To date, no consistent oncogenic driver mutations have been identified in most adult soft tissue sarcomas; these tumors are thus generally insensitive to existing targeted therapies. Here we investigated alternate mechanisms underlying sarcomagenesis to identify potential therapeutic interventions. Undifferentiated pleomorphic sarcoma (UPS) is an aggressive tumor frequently found in skeletal muscle where deregulation of the Hippo pathway and aberrant stabilization of its transcriptional effector yes-associated protein 1 (YAP1) increases proliferation and tumorigenesis. However, the downstream mechanisms driving this deregulation are incompletely understood. Using autochthonous mouse models and whole genome analyses, we found that YAP1 was constitutively active in some sarcomas due to epigenetic silencing of its inhibitor angiomotin (AMOT). Epigenetic modulators vorinostat and JQ1 restored AMOT expression and wild-type Hippo pathway signaling, which induced a muscle differentiation program and inhibited sarcomagenesis. YAP1 promoted sarcomagenesis by inhibiting expression of ubiquitin-specific peptidase 31 (USP31), a newly identified upstream negative regulator of NFκB signaling. Combined treatment with epigenetic modulators effectively restored USP31 expression, resulting in decreased NFκB activity. Our findings highlight a key underlying molecular mechanism in UPS and demonstrate the potential impact of an epigenetic approach to sarcoma treatment.Significance: A new link between Hippo pathway signaling, NFκB, and epigenetic reprogramming is highlighted and has the potential for therapeutic intervention in soft tissue sarcomas. Cancer Res; 78(10); 2705-20. ©2018 AACR.

Ubiquitin-specific protease 4 improves the prognosis of the patients in esophageal cancer.

Our study mainly investigated ubiquitin-specific protease 4 (USP4) expression in pathogenesis of esophageal cancer. The data showed significantly increased expression of USP4 in cancer tissues compared to that in para-carcinoma tissues (68.38% ± 25.60% vs 13.04% ± 9.95%, P= 0.000) and positive correlation between USP4 and pathology grade (r= 0.249, P= 0.014), although survival analysis revealed that USP4 expression was positively associated with the prognosis (32.4% vs 10.9%, P= 0.043). Grouped analysis revealed that the prognosis of patients with high USP4 expression were significantly better only in the small tumor subgroup (diameter ⩽ 5 cm) (52.6% VS 8.6%, P= 0.001) and the early stage subgroup (stages 1 and 2) (60.0% VS 16.7%, P= 0.006). Moreover, in the subgroup of clinical stages 1 and 2 with tumor diameter ⩽ 5 cm, high USP4 expression prolonged the survival time of esophageal cancer patients more significantly (75.5% VS 5.9%, P= 0.000). Based on these results, we speculated that it was possible to significantly improve the prognosis of patients with low USP4 expression by targeted therapy in early esophageal cancer. Taken together, our study uncovered a previously unknown function of USP4 in esophageal cancer and more investigations would be carried out to further study its regulation gene network and molecular biological mechanism in esophageal cancer.

High expression of ubiquitin-specific peptidase 39 is associated with the development of vascular remodeling.

Vascular remodeling is the primary cause underlying the failure of angioplasty surgeries, including vascular stenting, transplant vasculopathy and vein grafts. Multiple restenosis­associated proteins and genes have been identified to account for this. In the present study, the functions of ubiquitin­specific peptidase 39 (USP39) were investigated in the context of two vascular remodeling models (a mouse common carotid artery ligation and a pig bilateral saphenous vein­carotid artery interposition graft). USP39 has previously been observed to be upregulated in ligated arteries, and this result was confirmed in the pig vein graft model. In addition, Transwell assay results demonstrated that vascular smooth muscle cell (VSMC) migration was suppressed by lentiviral vector­mediated downregulation of USP39 and enhanced by upregulation of USP39. Furthermore, knockdown of USP39 inhibited VSMC cell proliferation and the expression of cyclin D1 and cyclin­dependent kinase 4, as analyzed via cell counting, MTT assay and western blotting. These results suggest that USP39 may represent a novel therapeutic target for treating vascular injury and preventing vein-graft failure.

In Vitro and in Vivo Analyses Reveal Profound Effects of Fibroblast Growth Factor 16 as a Metabolic Regulator.

The discovery of brown adipose tissue (BAT) as a key regulator of energy expenditure has sparked interest in identifying novel soluble factors capable of activating inducible BAT (iBAT) to combat obesity. Using a high content cell-based screen, we identified fibroblast growth factor 16 (FGF16) as a potent inducer of several physical and transcriptional characteristics analogous to those of both "classical" BAT and iBAT. Overexpression of Fgf16 in vivo recapitulated several of our in vitro findings, specifically the significant induction of the Ucp1 gene and UCP1 protein expression in inguinal white adipose tissue (iWAT), a common site for emergent active iBAT. Despite significant UCP1 up-regulation in iWAT and dramatic weight loss, the metabolic improvements observed due to Fgf16 overexpression in vivo were not the result of increased energy expenditure, as measured by indirect calorimetric assessment. Instead, a pattern of reduced food and water intake, combined with feces replete with lipid and bile acid, indicated a phenotype more akin to that of starvation and intestinal malabsorption. Gene expression analysis of the liver and ileum indicated alterations in several steps of bile acid metabolism, including hepatic synthesis and reabsorption. Histological analysis of intestinal tissue revealed profound abnormalities in support of this conclusion. The in vivo data, together with FGF receptor binding analysis, indicate that the in vivo outcome observed is the likely result of both direct and indirect mechanisms and probably involves multiple receptors. These results highlight the complexity of FGF signaling in the regulation of various metabolic processes.

Ubiquitin-specific protease 39 is overexpressed in human lung cancer and promotes tumor cell proliferation in vitro.

Lung cancer is the most frequent cancer in the world. Previous studies have shown that ubiquitin-specific protease 39 (USP39) is upregulated in several cancers and associated with tumor malignant characters. However, the effects of USP39 in lung cancer have not been well understood. In the present study, we found USP39 was generally expressed higher in human lung cancer tissues than in normal tissues by Oncomine database mining, qRT-PCR, and western blot assay. Knockdown of USP39 expression markedly reduced the proliferative and colony-forming ability of lung cancer cell lines 95D and A549. Flow cytometric analysis showed that USP39 knockdown induced cell cycle arrest at G2/M phase and enhanced cell apoptosis in 95D cells. Moreover, depletion of USP39 blocked activation of Akt, mTOR, p53, and PARP signaling pathways. Taken together, our study indicates that USP39 may be functionally involved in lung cancer growth and act as a potential molecular target for human lung cancer diagnosis and treatment.

Overexpression of USP39 predicts poor prognosis and promotes tumorigenesis of prostate cancer via promoting EGFR mRNA maturation and transcription elongation.

Castration resistance is a serious problem facing clinical treatment of prostate cancer (PCa). The underlying molecular mechanisms of acquired proliferation ability of tumor cells upon androgen deprivation are largely undetermined. In the present study, we identified that ubiquitin specific peptidase 39 (USP39) was significantly upregulated in PCa samples and cell lines. Elevated USP39 expression was positively correlated with Gleason score, predicted a poor outcome, and functioned as an independent risk factor for biochemical recurrence (BCR) especially in patients with a Gleason score ≤7. Our cell-based study showed that the expression level of USP39 was the highest in AR-negative PCa cell lines. Knockdown of USP39 in PCa cells inhibited cancer colony formation and tumor cell growth, and induced G2/M arrest and cell apoptosis. Microarray analysis suggested that knockdown of USP39 caused a reduced expression of EGFR. Silencing of USP39 inhibited the expression of EGFR 3'-end, and presented a remarkable block to the maturation of EGFR mRNA, suggesting that silencing of USP39 decreased the transcriptional elongation and maturation of EGFR mRNA. Oncomine datasets analysis showed that USP39 expression was positively correlated with EGFR level. The above findings suggest that USP39 plays a vital oncogenic role in the tumorigenesis of PCa and may prove to be a potential biomarker for predicting the prognosis of PCa patients.

A novel role for the deubiquitinase USP1 in the control of centrosome duplication.

Defects in the regulation of centrosome duplication lead to tumorigenesis through abnormal cell division and resulting chromosome missegregation. Therefore, maintenance of accurate centrosome number is critical for cell fate. The deubiquitinating enzyme USP1 plays important roles in DNA repair and cell differentiation. Importantly, increased levels of USP1 are detected in certain types of human cancer, but little is known about the significance of USP1 overexpression in cancer development. Here we show that Usp1 plays a novel role in regulating centrosome duplication. The ectopic expression of wild-type Usp1, but not C90S Usp1 (catalytically inactive mutant form), induced centrosome amplification. Conversely, ablation of Usp1 in mouse embryonic fibroblasts (MEFs) showed a significant delay in centrosome duplication. Moreover, Usp1-induced centrosome amplification caused abnormal mitotic spindles, chromosome missegregation and aneuploidy. Interestingly, loss of inhibitor of DNA binding protein 1 (ID1) suppressed Usp1-induced centrosome amplification. Taken together, our results strongly suggest that Usp1 is involved in the regulation of centrosome duplication, at least in part via ID1, and Usp1 may exert its oncogenic activity, partially through inducing centrosome abnormality.

The BAH domain of BAF180 is required for PCNA ubiquitination.

Monoubiquitination of proliferating cell nuclear antigen (PCNA) is a critical regulator of post replication repair (PRR). The depletion of BAF180, a unique subunit of the PBAF chromatin remodeling complex in human cells results in reduced PCNA ubiquitination leading to less efficient fork progression following DNA damage, but little is known about the mechanism. Here, we report that the expression of exogenous BAF180 in cells promotes PCNA ubiquitination during S-phase after UV irradiation and it persists for many hours. No correlation was observed between the protein level of ubiquitin-specific protease 1 (USP1) and ubiquitinated PCNA in BAF180 expressing cells. Analysis of cells expressing BAF180 deletion mutants showed that the bromo-adjacent homology (BAH) domains are responsible for this effect. Surprisingly, a deletion construct encoding only the BAH domain region is able to increase the level of ubiquitinated PCNA, even though it is unable to be assembled into the PBAF complex. These results suggest that the ATPase-dependent chromatin remodeling activity of PBAF is not necessary, but instead the BAH domains are sufficient to promote PCNA ubiquitination.

USP39 promotes the growth of human hepatocellular carcinoma in vitro and in vivo.

Ubiquitin specific protease 39 (USP39) plays an important role in mRNA splicing. In the present study, we investigated the role of USP39 in regulating the growth of hepatocellular carcinoma (HCC). We detected USP39 expression in more than 100 HCC clinical samples. The USP39 expression was significantly higher in the tumor tissues compared to the adjacent normal tissues, and was strongly associated with the pathological grade of HCC. USP39 knockdown inhibited cell proliferation and colony formation in vitro in the HepG2 cells, while upregulation of USP39 promoted tumor cell growth. FCM assay showed that USP39 knockdown led to G2/M arrest and induced apoptosis in the HepG2 cells. USP39 knockdown by shRNA inhibited xenograft tumor growth in nude mice. Moreover, USP39 knockdown led to the upregulation of p-Cdc2 and downregulation of p-Cdc25c and p-myt1, while the expression of total Cdc2, Cdc25c and myt1 was not changed in the USP39-knockdown cells. We also found that p-Cdc2 was decreased in the USP39-overexpressing cells and was upregulated in the xenografted tumors derived from the HepG2/KD cells from nude mice. Meanwhile, the expression levels of FoxM1 and its target genes PLK1 and cyclin B1 were decreased in the USP39-knockdown cells. These results suggest that USP39 may contribute to FoxM1 splicing in HCC tumor cells. Our data indicate that USP39 knockdown inhibited the growth of HCC both in vitro and in vivo through G2/M arrest, which was partly achieved via the inhibition of FoxM1 splicing.

Deubiquitinase DUBA is a post-translational brake on interleukin-17 production in T cells.

T-helper type 17 (TH17) cells that produce the cytokines interleukin-17A (IL-17A) and IL-17F are implicated in the pathogenesis of several autoimmune diseases. The differentiation of TH17 cells is regulated by transcription factors such as RORγt, but post-translational mechanisms preventing the rampant production of pro-inflammatory IL-17A have received less attention. Here we show that the deubiquitylating enzyme DUBA is a negative regulator of IL-17A production in T cells. Mice with DUBA-deficient T cells developed exacerbated inflammation in the small intestine after challenge with anti-CD3 antibodies. DUBA interacted with the ubiquitin ligase UBR5, which suppressed DUBA abundance in naive T cells. DUBA accumulated in activated T cells and stabilized UBR5, which then ubiquitylated RORγt in response to TGF-ß signalling. Our data identify DUBA as a cell-intrinsic suppressor of IL-17 production.

Biological functions of hyaluronan and cytokine-inducible deubiquitinating enzymes.

The modification of proteins through post-translation and degradation by the ubiquitin-proteasome system plays a pivotal role in a broad array of biological processes. Reversal of this process by deubiquitination is a central step in the maintenance and regulation of cellular homeostasis. It now appears that the regulation of ubiquitin pathways by deubiquitinating enzymes (DUBs) could be used as targets for anticancer therapy. Recent success in inducing apoptosis in cancerous cells by USP17, a cytokine-inducible DUB encoding two hyaluronan binding motifs (HABMs) showing direct interaction with hyaluronan (HA), could prove a promising step in the development of DUBs containing HABMs as agents in anticancer therapeutics. In this review, we summarize the importance of hyaluronan (HA) in cancer, the role played by DUBs in apoptosis, and a possible relationship between DUBs and HA in cancerous cells, suggesting new strategies for applying DUB enzymes as potential anticancer therapeutics.