OTUB1-catalyzed deubiquitination of FOXM1 facilitates tumor progression and predicts a poor prognosis in ovarian cancer

A drug repurposing study identifies novel FOXM1 inhibitors with in vitro activity against breast cancer cells

FOXM1, a proto-oncogenic transcription factor, plays a critical role in cancer development and treatment resistance in cancers, particularly in breast cancer. Thus, this study aimed to identify potential FOXM1 inhibitors through computational screening of drug databases, followed by in vitro validation of their inhibitory activity against breast cancer cells. In silico studies involved pharmacophore modeling using the FOXM1 inhibitor, FDI-6, followed by virtual screening of DrugBank and Selleckchem databases. The selected drugs were prepared for molecular docking, and the crystal structure of FOXM1 was pre-processed for docking simulations. In vitro studies included MTT assays to assess cytotoxicity, and Western blot analysis to evaluate protein expression levels. Our study identified Pantoprazole and Rabeprazole as potential FOXM1 inhibitors through in silico screening and molecular docking. Molecular dynamics simulations confirmed stable interactions of these drugs with FOXM1. In vitro experiments showed both Pantoprazole and Rabeprazole exhibited strong FOXM1 inhibition at effective concentrations and that showed inhibition of cell proliferation. Rabeprazole showed the inhibitor activity at 10 µM in BT-20 and MCF-7 cell lines. Pantoprazole exhibited FOXM1 inhibition at 30 µM and in BT-20 cells and at 70 µM in MCF-7 cells, respectively. Our current study provides the first evidence that Rabeprazole and Pantoprazole can bind to FOXM1 and inhibit its activity and downstream signaling, including eEF2K and pEF2, in breast cancer cells. These findings indicate that rabeprazole and pantoprazole inhibit FOXM1 and breast cancer cell proliferation, and they can be used for FOXM1-targeted therapy in breast or other cancers driven by FOXM1.

OTUB1/NDUFS2 axis promotes pancreatic tumorigenesis through protecting against mitochondrial cell death

Pancreatic cancer is one of the most fatal cancers in the world. A growing number of studies have begun to demonstrate that mitochondria play a key role in tumorigenesis. Our previous study reveals that NDUFS2 (NADH: ubiquinone oxidoreductase core subunit S2), a core subunit of the mitochondrial respiratory chain complex I, is upregulated in Pancreatic adenocarcinoma (PAAD). However, its role in the development of PAAD remains unknown. Here, we showed that NDUFS2 played a critical role in the survival, proliferation and migration of pancreatic cancer cells by inhibiting mitochondrial cell death. Additionally, protein mass spectrometry indicated that the NDUFS2 was interacted with a deubiquitinase, OTUB1. Overexpression of OTUB1 increased NDUFS2 expression at the protein level, while knockdown of OTUB1 restored the effects in vitro. Accordingly, overexpression and knockdown of OTUB1 phenocopied those of NDUFS2 in pancreatic cancer cells, respectively. Mechanically, NDUFS2 was deubiquitinated by OTUB1 via K48-linked polyubiquitin chains, resulted in an elevated protein stability of NDUFS2. Moreover, the growth of OTUB1-overexpressed pancreatic cancer xenograft tumor was promoted in vivo, while the OTUB1-silenced pancreatic cancer xenograft tumor was inhibited in vivo. In conclusion, we revealed that OTUB1 increased the stability of NDUFS2 in PAAD by deubiquitylation and this axis plays a pivotal role in pancreatic cancer tumorigenesis and development.

OTUB1-mediated inhibition of ubiquitination: a growing list of effectors, multiplex mechanisms, and versatile functions

Protein ubiquitination plays a pivotal role in protein homeostasis. Ubiquitination may regulate the stability, activity, protein-protein interaction, and localization of a protein. Ubiquitination is subject to regulation by two groups of counteracting enzymes, the E3 ubiquitin ligases and deubiquitinases. Consistently, deubiquitinases are involved in essentially all biological processes. OTUB1, an OTU-family deubiquitinase, is a critical regulator of development, cancer, DNA damage response, and immune response. OTUB1 antagonizes the ubiquitination of a wide-spectrum of proteins through at least two different mechanisms. Besides direct deubiquitination, OTUB1 can also inhibit ubiquitination by non-canonically blocking ubiquitin transfer from certain ubiquitin-conjugases (E2). In this review, we start with a general background of protein ubiquitination and deubiquitination. Next, we introduce the basic characteristics of OTUB1 and then elaborate on the updated biological functions of OTUB1. Afterwards, we discuss potential mechanisms underlying the versatility and specificity of OTUB1 functions. In the end, we discuss the perspective that OTUB1 can be a potential therapeutic target for cancer.

Involvement of the OTUB1-YAP1 axis in driving malignant behaviors of head and neck squamous cell carcinoma

BACKGROUND

Comprehending the molecular mechanisms underlying head and neck squamous cell carcinoma (HNSCC) is vital for the development of effective treatment strategies. Deubiquitinating enzymes (DUBs), which regulate ubiquitin-dependent pathways, are potential targets for cancer therapy because of their structural advantages. Here we aimed to identify a potential target for HNSCC treatment among DUBs.

METHODS

A screening process was conducted using RNA sequencing data and clinical information from HNSCC patients in the TCGA database. A panel of 88 DUBs was analyzed to identify those associated with poor prognosis. Subsequently, HNSCC cells were modified to overexpress specific DUBs, and their effects on cell proliferation and invasion were evaluated. In vivo experiments were performed to validate the findings.

RESULTS

In HNSCC patients, USP10, USP14, OTUB1, and STAMBP among the screened DUBs were associated with a poor prognosis. Among them, OTUB1 showed the most aggressive characteristics in both in vitro and in vivo experiments. Additionally, OTUB1 regulated the stability and nuclear localization of YAP1, a substrate involved in cell proliferation and invasion. Notably, OTUB1 expression exhibited a positive correlation with the HNSCC-YAP score in HNSCC cells.

CONCLUSIONS

This study highlights the critical role of OTUB1 in HNSCC progression via modulating YAP1. Targeting the OTUB1-YAP1 axis holds promise as a potential therapeutic strategy for HNSCC treatment.

Differential co-expression network analysis elucidated genes associated with sensitivity to farnesyltransferase inhibitor and prognosis of acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease and the most common form of acute leukemia with a poor prognosis. Due to its complexity, the disease requires the identification of biomarkers for reliable prognosis. To identify potential disease genes that regulate patient prognosis, we used differential co-expression network analysis and transcriptomics data from relapsed, refractory, and previously untreated AML patients based on their response to treatment in the present study. In addition, we combined functional genomics and transcriptomics data to identify novel and therapeutically potential systems biomarkers for patients who do or do not respond to treatment. As a result, we constructed co-expression networks for response and non-response cases and identified a highly interconnected group of genes consisting of SECISBP2L, MAN1A2, PRPF31, VASP, and SNAPC1 in the response network and a group consisting of PHTF2, SLC11A2, PDLIM5, OTUB1, and KLRD1 in the non-response network, both of which showed high prognostic performance with hazard ratios of 4.12 and 3.66, respectively. Remarkably, ETS1, GATA2, AR, YBX1, and FOXP3 were found to be important transcription factors in both networks. The prognostic indicators reported here could be considered as a resource for identifying tumorigenesis and chemoresistance to farnesyltransferase inhibitor. They could help identify important research directions for the development of new prognostic and therapeutic techniques for AML.

The deubiquitinase OTUB1 governs lung cancer cell fitness by modulating proteostasis of OXPHOS proteins

Aerobic glycolysis is a hallmark of cancer development, but this dogma has been challenged by reports showing a key role of oxidative phosphorylation (OXPHOS) in cancer cell survival. It has been proposed that increased levels of intramitochondrial proteins in cancer cells are associated with high OXPHOS activity and increased sensitivity to OXPHOS inhibitors. However, the molecular mechanisms leading to the high expression of OXPHOS proteins in cancer cells remain unknown. Multiple proteomics studies have detected the ubiquitination of intramitochondrial proteins, suggesting the contribution of the ubiquitin system to the proteostatic regulation of OXPHOS proteins. Here, we identified the ubiquitin hydrolase OTUB1 as a regulator of the mitochondrial metabolic machinery essential for lung cancer cell survival. Mitochondria-localized OTUB1 modulates respiration by inhibiting K48-linked ubiquitination and turnover of OXPHOS proteins. An increase in OTUB1 expression is commonly observed in one-third of non-small-cell lung carcinomas and is associated with high OXPHOS signatures. Moreover, OTUB1 expression highly correlates with the sensitivity of lung cancer cells to mitochondrial inhibitors.

Cellular Functions of Deubiquitinating Enzymes in Ovarian Adenocarcinoma

In ovarian cancer patients, the 5-year survival rate is 90% for stages I and II, but only 30% for stages III and IV. Unfortunately, as 75% of the patients are diagnosed at stages III and IV, many experience a recurrence. To ameliorate this, it is necessary to develop new biomarkers for early diagnosis and treatment. The ubiquitin-proteasome system is a post-translational modification that plays an important role in regulating protein stability through ubiquitination. In particular, deubiquitinating enzymes (DUBs) regulate protein stability through deubiquitinating substrate proteins. In this review, DUBs and substrates regulated by these enzymes are summarized based on their functions in ovarian cancer cells. This would be useful for the discovery of biomarkers for ovarian cancer and developing new therapeutic candidates.

Ubiquitination and deubiquitination in the regulation of epithelial-mesenchymal transition in cancer: Shifting gears at the molecular level

The process of conversion of non-motile epithelial cells to their motile mesenchymal counterparts is known as epithelial-mesenchymal transition (EMT), which is a fundamental event during embryonic development, tissue repair, and for the maintenance of stemness. However, this crucial process is hijacked in cancer and becomes the means by which cancer cells acquire further malignant properties such as increased invasiveness, acquisition of stem cell-like properties, increased chemoresistance, and immune evasion ability. The switch from epithelial to mesenchymal phenotype is mediated by a wide variety of effector molecules such as transcription factors, epigenetic modifiers, post-transcriptional and post-translational modifiers. Ubiquitination and de-ubiquitination are two post-translational processes that are fundamental to the ubiquitin-proteasome system (UPS) of the cell, and the shift in equilibrium between these two processes during cancer dictates the suppression or activation of different intracellular processes, including EMT. Here, we discuss the complex and dynamic relationship between components of the UPS and EMT in cancer.

Deubiquitinating enzyme OTUB1 in immunity and cancer: Good player or bad actor?

OTU domain-containing ubiquitin aldehyde-binding proteins 1 (OTUB1) is the most important element of the deubiquitinase OTU superfamily, which has been identified as an essential regulator of diverse physiological processes, such as DNA damage repair and cytokines secretion. Recently, we found that the pro-carcinogenesis role of OTUB1 and the relationship between OTUB1 and immune response have gradually become the research hot-spot. OTUB1 regulates NK/CD8 T cell activation, autoimmune diseases, PD-L1 mediated immune evasion, viral or bacterial infection related immune response and the occurrence and progression of various cancers via deubiquitinating and stabilizing related proteins. This review provides a comprehensive description about the role and regulatory axis of OTUB1. We can explore the balance between immune response and defense via regulating the level of OTUB1, and targeting OTUB1 might restrain the progression of cancers. This review highlights the experimental evidence that OTUB1 is a feasible and potential therapeutic target against various cancers progression and immune diseases or disorder.

RNF126 is a positive regulator of TRAF3 ubiquitination

Ubiquitination and deubiquitination of signaling molecules are critical regulatory mechanisms in various biological contexts such as inflammatory signaling and the DNA damage response. Thus, finely tuned regulation of protein ubiquitination is essential for maintaining cellular homeostasis. Here, we showed that the RING finger protein RNF126 interacts with TRAF3 and promotes its K63-linked polyubiquitination, which is a crucial step in the TRAF3-dependent antiviral response. We found that RNF126 also interacts with OTUB1, a deubiquitinating enzyme that negatively regulates K63-linked ubiquitination of TRAF3. RNF126 promotes ubiquitination of OTUB1, leading to reduced deubiquitinating activity toward TRAF3. Moreover, RNF126 promotes ubiquitination of OTUB1 on cysteine 91, which is reportedly required for its catalytic activity. Taken together, our results suggest that RNF126 positively regulates the antiviral response by directly promoting K63-linked polyubiquitination of TRAF3 and by reducing OTUB1 activity.

FOXM1: A Multifunctional Oncoprotein and Emerging Therapeutic Target in Ovarian Cancer

Forkhead box M1 (FOXM1) is a member of the conserved forkhead box (FOX) transcription factor family. Over the last two decades, FOXM1 has emerged as a multifunctional oncoprotein and a robust biomarker of poor prognosis in many human malignancies. In this review article, we address the current knowledge regarding the mechanisms of regulation and oncogenic functions of FOXM1, particularly in the context of ovarian cancer. FOXM1 and its associated oncogenic transcriptional signature are enriched in >85% of ovarian cancer cases and FOXM1 expression and activity can be enhanced by a plethora of genomic, transcriptional, post-transcriptional, and post-translational mechanisms. As a master transcriptional regulator, FOXM1 promotes critical oncogenic phenotypes in ovarian cancer, including: (1) cell proliferation, (2) invasion and metastasis, (3) chemotherapy resistance, (4) cancer stem cell (CSC) properties, (5) genomic instability, and (6) altered cellular metabolism. We additionally discuss the evidence for FOXM1 as a cancer biomarker, describe the rationale for FOXM1 as a cancer therapeutic target, and provide an overview of therapeutic strategies used to target FOXM1 for cancer treatment.

Research Progress in Prognostic Factors and Biomarkers of Ovarian Cancer

Ovarian cancer is a serious threat to women's health; its early diagnosis rate is low and prone to metastasis and recurrence. The current conventional treatment for ovarian cancer is a combination of platinum and paclitaxel chemotherapy based on surgery. The recurrence and progression of ovarian cancer with poor prognosis is a major challenge in treatment. With rapid advances in technology, understanding of the molecular pathways involved in ovarian cancer recurrence and progression has increased, biomarker-guided treatment options can greatly improve the prognosis of patients. This review systematically discusses and summarizes existing and new information on prognostic factors and biomarkers of ovarian cancer, which is expected to improve the clinical management of patients and lead to effective personalized treatment.

The functions and regulation of Otubains in protein homeostasis and diseases

OTU domain-containing ubiquitin aldehyde-binding proteins Otubain1 (OTUB1) and Otubain2 (OTUB2) were initially identified as OTU deubiquitinases (DUBs). Recently, Otubains have emerged as essential regulators of diverse physiological processes, such as immune signaling and DNA damage response. Dysregulation of those processes is likely to increase the risk in multiple aspects of aging-related diseases, including cancers, neurodegenerative disorders, chronic kidney diseases, bone dysplasia and pulmonary fibrosis. Consistently, Otubains are aberrantly expressed in cancers and have been identified to be both tumor suppressors and tumor promoters in different types of cancers. Therefore, the regulatory mechanism of the activity and expression of Otubains is very important for better understanding of Otubains-associated biological networks and human diseases. This review provides a comprehensive description of functions and regulatory axis of Otubains, highlighting experimental evidences indicating Otubains as potential therapeutic targets against aging-related disorders.

FOXM1 and Cancer: Faulty Cellular Signaling Derails Homeostasis

Forkhead box transcription factor, FOXM1 is implicated in several cellular processes such as proliferation, cell cycle progression, cell differentiation, DNA damage repair, tissue homeostasis, angiogenesis, apoptosis, and redox signaling. In addition to being a boon for the normal functioning of a cell, FOXM1 turns out to be a bane by manifesting in several disease scenarios including cancer. It has been given an oncogenic status based on several evidences indicating its role in tumor development and progression. FOXM1 is highly expressed in several cancers and has also been implicated in poor prognosis. A comprehensive understanding of various aspects of this molecule has revealed its role in angiogenesis, invasion, migration, self- renewal and drug resistance. In this review, we attempt to understand various mechanisms underlying FOXM1 gene and protein regulation in cancer including the different signaling pathways, post-transcriptional and post-translational modifications. Identifying crucial molecules associated with these processes can aid in the development of potential pharmacological approaches to curb FOXM1 mediated tumorigenesis.

OTUB1 Promotes Progression and Proliferation of Prostate Cancer via Deubiquitinating and Stabling Cyclin E1

Background: Prostate cancer (PCa) is currently the most common cancer among males worldwide. It has been reported that OTUB1 plays a critical role in a variety of tumors and is strongly related to tumor proliferation, migration, and clinical prognosis. The aim of this research is to investigate the regulatory effect of OTUB1 on PCa proliferation and the underlying mechanism. Methods: Using the TCGA database, we identified that OTUB1 was up-regulated in PCa, and observed severe functional changes in PC3 and C4-2 cells through overexpression or knock down OTUB1. Heterotopic tumors were implanted subcutaneously in nude mice and IHC staining was performed on tumor tissues. The relationship between OTUB1 and cyclin E1 was identified via Western blotting and immunoprecipitations assays. Results: We found that the expression of OTUB1 in PCa was significantly higher than that in Benign Prostatic Hyperplasia (BPH). Overexpression OTUB1 obviously promoted the proliferation and migration of PC3 and C4-2 cells via mediating the deubiquitinated Cyclin E1, while OTUB1 knockout has the opposite effect. The nude mice experiment further explained the above conclusions. We finally determined that OTUB1 promotes the proliferation and progression of PCa via deubiquitinating and stabling Cyclin E1. Conclusions: Our findings reveal the critical role of OTUB1 in PCa, and OTUB1 promotes the proliferation and progression of PCa via deubiquitinating and stabilizing Cyclin E1. Blocking OTUB1/Cyclin E1 axis or applying RO-3306 could significantly repress the occurrence and development of PCa. OTUB1/Cyclin E1 axis might provide a new and potential therapeutic target for PCa.

OTUB1 Recruits Tumor Infiltrating Lymphocytes and Is a Prognostic Marker in Digestive Cancers

Background

The deubiquitinating enzyme (DUB) OTUB1 can regulate the process of ubiquitination, but the influence of OTUB1 on immunity, apoptosis, autophagy, and the prognosis of digestive cancers requires further exploration.

Methods

OTUB1 expression was analyzed with the Oncomine and TIMER database. Kaplan-Meier plotter was used to calculate the association between OTUB1 and clinical prognosis. The regulation of OTUB1 on cancer immunocyte infiltration was determined by the TIMER database. The interaction between OTUB1 and immune genes, gene expression profiling (GEP), key genes of apoptosis and autophagy were analyzed via GEPIA. Protein-protein interaction (PPI), gene expression profiling (GEP), and functional pathway enrichment were also performed with the STRING and Pathway Common databases, respectively.

Results

High OTUB1 expression was found in CHOL, LIHC, READ, ESCA, and COAD, which was significantly associated with the poorer OS of LIHC (HR = 2.07, 95% CI = 1.30-3.30, P = 0.002), with modifications by sex, stage, grade, and mutant burden. OTUB1 can promote the recruitment of B cells, CD8 + T cells, macrophages in ESCA, B cells, and neutrophils in LIHC. We determined a significant interaction between OTUB1 and USP8, RNF128, LRIG1, UBB, UBC, STAM2, RNF41, EGFR, RPS27A, and HGS by PPI. This functional pathway indicates the regulatory role of OTUB1on immune, apoptosis, and autophagy through its interaction with TP53 and ATG.

Conclusions

OTUB1 performed as a molecular indicator of poor prognosis in digestive cancers, regulated the infiltration of tumor immunocytes, and exerted a significant influence on apoptosis and autophagy. OTUB1 is a potential antitumor target for digestive tumors.

FoxM1 promotes the migration of ovarian cancer cell through KRT5 and KRT7

Forkhead box M1(FoxM1) played an important role in the pathogenesis of ovarian cancer, but its downstream molecular network is mysterious. Here, we combined ChIP-seq with RNA-seq analysis and identified 687 FoxM1-binding regions and 182 genes regulated by FoxM1. The above data pointed out that KRT5 and KRT7 were downstream target genes of FoxM1. Next, we used qPCR and Western blot to verify that FoxM1 knockdown inhibited the expression levels of KRT5 and KRT7. We also demonstrated that FoxM1 regulated KRT5 and KRT7 genes expression through binding a consensus AP-2 cis element, and showed that KRT5 and KRT7 deficiency could prevent the migration but not proliferation of SK-OV-3 cells. Finally, tissue microarray results indicated that KRT5 and KRT7 were highly expressed in ovarian cancer and positively correlated with FoxM1 expression. TCGA database showed that high expression of KRT5 and KRT7 could significantly reduce the survival rate of patients with ovarian cancer. The above results clarify the specific downstream molecular network of FoxM1 to promote the pathogenesis of ovarian cancer, and provide a basis experiment for the judgment of ovarian cancer prognosis and the design of drug targets.

OTUB1-mediated deubiquitination of FOXM1 up-regulates ECT-2 to promote tumor progression in renal cell carcinoma

Background

OTUB1 (ovarian tumor domain protease domain-containing ubiquitin aldehyde-binding proteins)-mediated deubiquitination of FOXM1 (Forkhead box M1) participates in carcinogenesis of various tumors. We aim to investigate the effect and mechanism of OTUB1/FOXM1 on RCC (renal cell carcinoma) progression. Expression levels of OTUB1 in RCC tissues and cell lines were examined by qRT-PCR (quantitative real-time polymerase chain reaction) and immunohistochemistry. Cell proliferation was measured with CCK8 (Cell Counting Kit-8) and colony formation assays. Wound healing and transwell assays were used to determine cell migration and invasion, respectively. The effect of OTUB1 on FOXM1 ubiquitination was examined by Immunoprecipitation. Western blot was used to uncover the underlying mechanism. In vivo subcutaneous xenotransplanted tumor model combined with immunohistochemistry and western blot were used to examine the tumorigenic function of OTUB1.

Results

OTUB1 was up-regulated in RCC tissues and cell lines, and was associated with poor prognosis of RCC patients. Knockdown of OTUB1 inhibited cell viability and proliferation, as well as migration and invasion of RCC cells. Mechanistically, knockdown of OTUB1 down-regulated FOXM1 expression by promoting its ubiquitination. Down-regulation of FOXM1 inhibited ECT2 (epithelial cell transforming 2)-mediated Rho signaling. Moreover, the inhibition of RCC progression caused by OTUB1 knockdown was reversed by FOXM1 over-expression. In vivo subcutaneous xenotransplanted tumor model also revealed that knockdown of OTUB1 could suppress in vivo RCC growth via down-regulation of FOXM1-mediated ECT2 expression.

Conclusions

OTUB1-mediated deubiquitination of FOXM1 up-regulates ECT-2 to promote tumor progression in RCC, providing a new potential therapeutic target for RCC treatment.

Comparison of Cross-Regulation by Different OTUB1:E2 Complexes

OTUB1 is a highly expressed cysteine protease that specifically cleaves K48-linked polyubiquitin chains. This unique deubiquitinating enzyme (DUB) can bind to a subset of E2 ubiquitin conjugating enzymes, forming complexes in which the two enzymes can regulate one another's activity. OTUB1 can noncatalytically suppress the ubiquitin conjugating activity of its E2 partners by sequestering the charged E2∼Ub thioester and preventing ubiquitin transfer. The same E2 enzymes, when uncharged, can stimulate the DUB activity of OTUB1 in vitro, although the importance of OTUB1 stimulation in vivo remains unclear. To assess the potential balance between these activities that might occur in cells, we characterized the kinetics and thermodynamics governing the formation and activity of OTUB1:E2 complexes. We show that both stimulation of OTUB1 by E2 enzymes and noncatalytic inhibition of E2 enzymes by OTUB1 occur at physiologically relevant concentrations of both partners. Whereas E2 partners differ in their ability to stimulate OTUB1 activity, we find that this variability is not correlated with the affinity of each E2 for OTUB1. In addition to UBE2N and the UBE2D isoforms, we find that OTUB1 inhibits the polyubiquitination activity of all three UBE2E enzymes, UBE2E1, UBE2E2, and UBE2E3. Interestingly, although OTUB1 also inhibits the auto-monoubiquitination and autopolyubiquitination activity of UBE2E1 and UBE2E2, it is unable to suppress autoubiquitination by UBE2E3. Our quantitative analysis provides a basis for further exploring the biological roles of OTUB1:E2 complexes in cells.

High expression of FOXM1 critical for sustaining cell proliferation in mitochondrial DNA-less liver cancer cells

The copy number of mitochondrial DNA (mtDNA) is decreased in most cancer types, including hepatocellular carcinoma (HCC), compared to normal counterparts. However, a decrease in mtDNA usually leads to defects in cell proliferation, which contradicts the robustness of cancer cell proliferation. In this study, we found that four out of seven HCC cell lines were of the mtDNA-less type. Interestingly, FOXM1, a member of the FOX transcription factor family, was highly expressed in a subset of them with proliferative potential maintained. B-MYB, a partner of FOXM1, was also expressed in the same cell lines. RNAi-mediated experiments demonstrated that when FOXM1/B-MYB was silenced in the cell lines, cell cycle-related genes were downregulated, while p21^Cip1 was induced with senescence-associated β-galactosidase, resulting in G₁/S cell cycle arrest. These results suggest that high expression of FOXM1/B-MYB is critical for sustaining cell proliferation in mtDNA-less cells. In addition, we found that high expression of FOXM1 was mediated by the deubiquitinating enzyme, OTUB1, in one cell line. Thus, interference with FOXM1/B-MYB expression, such as through OTUB1 inhibition, may induce a dormant state of senescence-like proliferation arrest in mtDNA-less cancer cells. This finding may be utilized for the development of precision medicine for relevant cancers.

MicroRNA‑542‑3p represses OTUB1 expression to inhibit migration and invasion of esophageal cancer cells

Dysregulation of microRNAs (miRNAs) is involved in the pathogenesis of esophageal cancer. miRNA (miR)‑542‑3p is a tumor suppressor in multiple types of cancer. However, whether and how miR‑542‑3p contributes to the progression of esophageal cancer remains unknown, and this is the aim of the present study. In the current study, decreased expression of miR‑542‑3p was detected in tumor tissues compared with normal tissues from patients with esophageal cancer, and miR‑542‑3p expression was negatively correlated with mRNA expression levels of ovarian tumor domain‑containing ubiquitin aldehyde‑binding protein 1 (OTUB1) in tumor tissues from patients with esophageal cancer. In KYSE150 human esophageal squamous cell carcinoma cells, overexpression of miR‑542‑3p significantly decreased OTUB1 at mRNA and protein levels, whereas downregulation of miR‑542‑3p significantly increased OTUB1 expression. Using a dual‑luciferase assay, OTUB1 was validated to be a target gene of miR‑542‑3p in KYSE150 cells. Functionally, miR‑542‑3p significantly inhibited the migration and invasion of KYSE150 cells by repression of OTUB1 expression. These results demonstrated that miR‑542‑3p may promote the metastasis of esophageal cancer cells, and indicated that miR‑542‑3p may be a treatment target for esophageal cancer.

ERRα Regulates OTUB1 Expression to Promote Colorectal Cancer Cell Migration

Ovarian tumor domain-containing ubiquitin aldehyde binding protein 1 (OTUB1) is overexpressed in many cancers and plays an important role in tumor progression and metastasis. However, the molecular mechanisms underlying OTUB1 overexpression are not clear. In this study, we found that estrogen-related receptor alpha (ERRα, also called NR3B1) binds to OTUB1 promoter and regulates its expression in colorectal cancer. Furthermore, ERRα promoted the migration of CRC cells by inducing vimentin expression via OTUB1. Our data show that OTUB1 is a novel target of ERRα and indicate that ERRα-OTUB1 signaling may play a significant role in CRC metastasis.

UCHL3 promotes pancreatic cancer progression and chemo-resistance through FOXM1 stabilization

The dysregulation of deubiquitinating enzymes has been reported to be important in the development of many human cancers, including pancreatic cancer. However, the precise role and potential mechanism of action of the deubiquitinating enzyme UCHL3 in pancreatic cancer progression and chemo-resistance, are poorly elucidated. In the current study, the consequences of UCHL3 knockdown in pancreatic cancer cells were evaluated via cell viability and colony formation assays. In vivo experiments were also conducted to confirm the effect of UCHL3 and FOXM1 depletion on tumor growth in nude mouse xenograft models. Cell migration and invasion were assessed by wound-healing and transwell assays, respectively. Co-immunoprecipitation (co-IP) and in vitro deubiquitination assays were performed to investigate the interactions between UCHL3 and FOXM1. Immunohistochemical (IHC) staining was utilized to examine the expression of UCHL3 and FOXM1 in pancreatic cancer tissues. Our results demonstrate that UCHL3 deubiquitinated and stabilized FOXM1, thereby potentiating proliferation, migration, and invasion of pancreatic cancer cells. Furthermore, knockdown of UCHL3 increased FOXM1 ubiquitination, which enhanced FOXM1 turnover and promoted pancreatic cancer cells' sensitivity to gemcitabine. High UCHL3 expression was positively associated with FOXM1 expression level in pancreatic cancer patient samples. Collectively, our study established the UCHL3-FOXM1 axis as a pivotal driver of pancreatic cancer progression and gemcitabine resistance and provided evidence for the potential therapeutic benefit of targeting the UCHL3-FOXM1 axis for pancreatic cancer treatment.

OTUB1 inhibits CNS autoimmunity by preventing IFN-γ-induced hyperactivation of astrocytes

Astrocytes are critical regulators of neuroinflammation in multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE). Growing evidence indicates that ubiquitination of signaling molecules is an important cell-intrinsic mechanism governing astrocyte function during MS and EAE Here, we identified an upregulation of the deubiquitinase OTU domain, ubiquitin aldehyde binding 1 (OTUB1) in astrocytes during MS and EAE Mice with astrocyte-specific OTUB1 ablation developed more severe EAE due to increased leukocyte accumulation, proinflammatory gene transcription, and demyelination in the spinal cord as compared to control mice. OTUB1-deficient astrocytes were hyperactivated in response to IFN-γ, a fingerprint cytokine of encephalitogenic T cells, and produced more proinflammatory cytokines and chemokines than control astrocytes. Mechanistically, OTUB1 inhibited IFN-γ-induced Janus kinase (JAK)/signal transducer and activator of transcription (STAT) signaling by K48 deubiquitination and stabilization of the JAK2 inhibitor suppressor of cytokine signaling 1 (SOCS1). Thus, astrocyte-specific OTUB1 is a critical inhibitor of neuroinflammation in CNS autoimmunity.

Ovarian tumor domain-containing ubiquitin aldehyde binding protein 1 inhibits inflammation by regulating Nur77 stability

Nur77 (NR4A1) plays an important role in various inflammatory responses. Nur77 is rapidly degraded in cells and its protein level is critically controlled. Although few E3 ligases regulating the Nur77 protein have been defined, the deubiquitinase (DUB) responsible for Nur77 stability has not been reported to date. We identified ovarian tumor domain-containing ubiquitin aldehyde binding protein 1 (OTUB1) as a DUB that stabilizes Nur77 by preventing its proteasomal degradation. We found that OTUB1 interacted with Nur77 to deubiquitinate it, thereby stabilizing Nur77 in an Asp88-dependent manner. This suggests that OTUB1 targets Nur77 for deubiquitination via a non-canonical mechanism. Functionally, OTUB1 inhibited TNFα-induced IL-6 production by promoting Nur77 protein stability. OTUB1 modulated the stability of Nur77 as a counterpart of tripartite motif 13 (Trim13). That is, OTUB1 reduced the ubiquitination and degradation of Nur77 potentiated by Trim13. In addition, this DUB also inhibited IL-6 production, which was further amplified by Trim13 in TNFα-induced responses. These findings suggest that OTUB1 is an important regulator of Nur77 stability and plays a role in controlling the inflammatory response.

Anti-tumor effects and potential therapeutic response biomarkers in α-emitting meta-211At-astato-benzylguanidine therapy for malignant pheochromocytoma explored by RNA-sequencing

Targeted α-particle therapy is a promising option for patients with malignant pheochromocytoma. Recent observations regarding meta-²¹¹At-astato-benzylguanidine (²¹¹At-MABG) in a pheochromocytoma mouse model showed a strong anti-tumor effect, though the molecular mechanism remains elusive. Here, we present the first comprehensive RNA-sequencing (RNA-seq) data for pheochromocytoma cells based on in vitro²¹¹At-MABG administration experiments. Key genes and pathways in the tumor α-particle radiation response are also examined to obtain potential response biomarkers.

Methods: We evaluated genome-wide transcriptional alterations in the rat pheochromocytoma cell line PC12 at 3, 6, and 12 h after ²¹¹At-MABG treatment; a control experiment using ⁶⁰Co γ-ray irradiation was carried out to highlight ²¹¹At-MABG-specific gene expression. For comparisons, 10% and 80% iso-survival doses (0.8 and 0.1 kBq/mL for ²¹¹At-MABG and 10 and 1 Gy for ⁶⁰Co γ-rays) were used.

Results: Enrichment analysis of differentially expressed genes (DEGs) and analysis of the gene expression profiles of cell cycle checkpoints revealed similar modes of cell death via the p53-p21 signaling pathway after ²¹¹At-MABG treatment and γ-ray irradiation. The top list of ranked DEGs demonstrated the expression of key genes on the decrease in the survival following ²¹¹At-MABG exposure, and four potential genes (Mien1, Otub1, Vdac1 and Vegfa genes) of ²¹¹At-MABG therapy. Western blot analysis indicated increased expression of TSPO in ²¹¹At-MABG-treated cells, suggesting its potential as a PET imaging probe.

Conclusion: Comprehensive RNA-seq revealed contrasting cellular responses to γ-ray and α-particle therapy, leading to the identification of four potential candidate genes that may serve as molecular imaging and ²¹¹At-MABG therapy targets.

TGF-β signaling pathway mediated by deubiquitinating enzymes

Ubiquitination is a reversible cellular process mediated by ubiquitin-conjugating enzymes, whereas deubiquitinating enzymes (DUBs) detach the covalently conjugated ubiquitin from target substrates to counter ubiquitination. DUBs play a crucial role in regulating various signal transduction pathways and biological processes including apoptosis, cell proliferation, DNA damage repair, metastasis, differentiation, etc. Since the transforming growth factor-β (TGF-β) signaling pathway participates in various cellular functions such as inflammation, metastasis and embryogenesis, aberrant regulation of TGF-β signaling induces abnormal cellular functions resulting in numerous diseases. This review focuses on DUBs regulating the TGF-β signaling pathway. We discuss the molecular mechanisms of DUBs involved in TGF-β signaling pathway, and biological and therapeutic implications for various diseases.

Otubain 1: a non-canonical deubiquitinase with an emerging role in cancer

The ubiquitin system regulates diverse biological processes, many involved in cancer pathogenesis, by altering the ubiquitination state of protein substrates. This is accomplished by ubiquitin ligases and deubiquitinases (DUBs), which respectively add or remove ubiquitin from substrates to alter their stability, activity, localization and interactions. While lack of catalytic activity makes therapeutic targeting of ubiquitin ligases difficult, DUB inhibitors represent an active area of research and the identification of cancer-associated DUBs may lead to the development of novel therapeutics. A growing body of literature demonstrates that the DUB Otubain 1 (OTUB1) regulates many cancer-associated signaling pathways including MAPK, ERa, epithelial-mesenchymal transition (EMT), RHOa, mTORC1, FOXM1 and P53 to promote tumor cell survival, proliferation, invasiveness and therapeutic resistance. In addition, clinical studies have associated elevated OTUB1 expression with high grade, invasiveness and metastasis in several tumor types including lung, breast, ovarian, glioma, colon and gastric. Interestingly, in addition to catalytic DUB activity, OTUB1 displays a catalytic-independent, non-canonical activity where it inhibits the transfer of ubiquitin onto protein substrates by sequestration of E2 ubiquitin-conjugating enzymes. The aim of this review is to describe the canonical and non-canonical activities of OTUB1, summarize roles for OTUB1 in cancer-associated pathways and discuss its potential therapeutic targeting.

Regulation of the master regulator FOXM1 in cancer

FOXM1 (forkhead box protein M1) is a critical proliferation-associated transcription factor that is widely spatiotemporally expressed during the cell cycle. It is closely involved with the processes of cell proliferation, self-renewal, and tumorigenesis. In most human cancers, FOXM1 is overexpressed, and this indicates a poor prognosis for cancer patients. FOXM1 maintains cancer hallmarks by regulating the expression of target genes at the transcriptional level. Due to its potential role as molecular target in cancer therapy, FOXM1 was named the Molecule of the Year in 2010. However, the mechanism of FOXM1 dysregulation remains indistinct. A comprehensive understanding of FOXM1 regulation will provide novel insight for cancer and other diseases in which FOXM1 plays a major role. Here, we summarize the transcriptional regulation, post-transcriptional regulation and post-translational modifications of FOXM1, which will provide extremely important implications for novel strategies targeting FOXM1.

The non-coding RNA OTUB1-isoform2 promotes ovarian tumour progression and predicts poor prognosis

Ovarian cancer is the leading malignancy of the female reproductive system and is associated with inconspicuous early invasion and metastasis. We have previously reported that the oncogene OTUB1 plays a crucial role in ovarian cancer progression, but the role of its isoform, the non‐coding RNA OTUB1‐isoform2, in ovarian cancer is still elusive. Here, we reported that OTUB1‐isoform2 expression in ovarian cancer tissues was significantly higher than that in the paired paratumorous tissues (P < .01). The patients with high expression of OTUB1‐isoform2 had larger tumours than those with low expression (P < .05). The high expression of OTUB1‐isoform2 was correlated with the involvement of bilateral ovaries (P < .05), lymph node metastasis (P < .05), vascular invasion (P < .05), greater omentum involvement (P < .01), fallopian tube involvement (P < .05), advanced FIGO stages (P < .01) and recurrence (P < .01). Moreover, OTUB1‐isoform2 served as an independent negative prognostic predictor for disease‐free survival (DFS) and disease‐specific survival (DSS). Overexpression of OTUB1‐isoform2 in the ovarian cancer cells stimulated cell proliferation, migration and invasion both in vitro and in vivo. In summary, our study suggested that OTUB1‐isoform2 is a novel prognostic biomarker with independent oncogenic functions for ovarian cancer.

OTUB1 promotes esophageal squamous cell carcinoma metastasis through modulating Snail stability

Snail is a key regulator of epithelial-mesenchymal transition (EMT) and plays an important role in tumor progression and metastasis. Snail is rapidly degraded in the cells and its protein level is critically controlled. Although several E3 ligases regulating Snail degradation have been defined, the deubiquitinases (DUBs) responsible for Snail deubiquitination are less studied. We identified ovarian tumor domain-containing ubiquitin aldehyde binding protein 1 (OTUB1) as a DUB that stabilizes Snail through preventing its ubiquitination and proteasomal degradation. Functionally, OTUB1 facilitates metastasis of esophageal squamous cell carcinoma (ESCC) through promoting Snail protein stability. Moreover, OTUB1 is highly expressed in ESCC and higher expression of OTUB1 predicts poor prognosis. These findings suggest that OTUB1 is an essential regulator of Snail and plays a critical role in facilitating esophageal cancer progression.

Genome-wide association analysis identifies multiple loci associated with kidney disease-related traits in Korean populations

Chronic kidney disease (CKD) is an important social health problem characterized by a decrease in the kidney glomerular filtration rate (GFR). In this study, we analyzed genome-wide association studies for kidney disease-related traits using data from a Korean adult health screening cohort comprising 7,064 participants. Kidney disease-related traits analyzed include blood urea nitrogen (BUN), serum creatinine, estimated GFR, and uric acid levels. We detected two genetic loci (SLC14A2 and an intergenic region) and 8 single nucleotide polymorphisms (SNPs) associated with BUN, 3 genetic loci (BCAS3, C17orf82, ALDH2) and 6 SNPs associated with serum creatinine, 3 genetic loci (BCAS3, C17orf82/TBX2, LRP2) and 7 SNPs associated with GFR, and 14 genetic loci (3 in ABCG2/PKD2, 2 in SLC2A9, 3 in intergenic regions on chromosome 4; OTUB1, NRXN2/SLC22A12, CDC42BPG, RPS6KA4, SLC22A9, and MAP4K2 on chromosome 11) and 84 SNPs associated with uric acid levels. By comparing significant genetic loci associated with serum creatinine levels and GFR, rs9895661 in BCAS3 and rs757608 in C17orf82 were simultaneously associated with both traits. The SNPs rs11710227 in intergenic regions on chromosome 3 showing significant association with BUN is newly discovered. Genetic variations of multiple gene loci are associated with kidney disease-related traits, and differences in associations between kidney disease-related traits and genetic variation are dependent on the population. The meanings of the mutations identified in this study will need to be reaffirmed in other population groups in the future.

Untying the knot of transcription factor druggability: Molecular modeling study of FOXM1 inhibitors

The FOXM1 protein is a relevant transcription factor involved in cancer cell proliferation. The direct or indirect inhibition of this protein's transcriptional activity by small molecule drugs correlates well with a potentially significant anti-cancer profile, making this macro molecule a promising drug target. There are a few drug molecules reported to interact with (and inhibit) the FOXM1 DNA binding domain (FOXM1-BD), causing downregulation of protein expression and cancer cell proliferation inhibition. Among these drug molecules are the proteasome inhibitor thiostrepton, the former antidiabetic drug troglitazone, and the new FDI-6 molecule. Despite their structural differences, these drugs exert a similar inhibitory profile, and this observation prompted us to study a possible similar mechanism of action. Using a series of molecular dynamics simulations and docking protocols, we identified essential binding interactions exerted by all three classes of drugs, among which, a π-sulfur interaction (between a His287 and a sulfur-containing heterocycle) was the most important. In this report, we describe the preliminary evidence suggesting the presence of a drug-binding pocket within FOXM1 DNA binding domain, in which inhibitors fit to dissociate the protein-DNA complex. This finding suggests a common mechanism of action and a basic framework to design new FOXM1 inhibitors.

OTUB1 protein suppresses mTOR complex 1 (mTORC1) activity by deubiquitinating the mTORC1 inhibitor DEPTOR

Mechanistic target of rapamycin (mTOR) complex 1 (mTORC1) integrates various environmental signals to regulate cell growth and metabolism. DEPTOR, also termed DEPDC6, is an endogenous inhibitor of mTORC1 and mTORC2 activities. The abundance of DEPTOR centrally orchestrates the mTOR signaling network. However, the mechanisms by which DEPTOR stability is regulated are still elusive. Here, we report that OTU domain-containing ubiquitin aldehyde-binding protein 1 (OTUB1) specifically deubiquitinates DEPTOR in a deubiquitination assay. We found that OTUB1 directly interacted with DEPTOR via its N-terminal domain, deubiquitinated DEPTOR, and thereby stabilized DEPTOR in a Cys-91-independent but Asp-88-dependent manner, suggesting that OTUB1 targets DEPTOR for deubiquitination via a deubiquitinase activity-independent non-canonical mechanism. The interaction between OTUB1 and DEPTOR was enhanced when the cells were treated with amino acids. Moreover, OTUB1 suppressed amino acid-induced activation of mTORC1 in a DEPTOR-dependent manner and thereby ultimately controlled cellular autophagy, cell proliferation, and size. Our findings reveal a mechanism that stabilizes the mTORC1 inhibitor DEPTOR via OTUB1's deubiquitinase activity. Our insights may inform research into various mTOR activity-related diseases, such as cancer, and may contribute to the identification of new diagnostic markers and therapeutic strategies for cancer treatments.

Suppressor of fused (Sufu) promotes epithelial-mesenchymal transition (EMT) in cervical squamous cell carcinoma

Suppressor of fused is essential for the maximal activation of Sonic Hedgehog signaling in development and tumorigenesis. However, the role of Sufu in cervical carcinoma remains unknown. Here, we report new findings of Sufu in regulating the epithelial-to-mesenchymal transition through the FoxM1 transcriptional modulation by 14-3-3ζ protein in cervical carcinoma. Sufu is overexpressed in cervical squamous cell carcinoma and its level in clinical tumor tissues is positively correlated with 14-3-3ζ. Functionanlly, siSufu remarkably prevents the cancer cell migration and invasion. We further demonstrate that the transcriptional activity of Sufu is increased by FoxM1, of which stability is promoted by 14-3-3ζ. Knockdown FoxM1 decreases the invasion of SiHa cells and reconstitution of Sufu rescues the invasion of these cells.Finally, overexpression of Sufu is significantly associated with differentiation grade, FIGO stage, Depth of stromal invasion and vascular cancer embolus. Our findings highlight a novel role for Sufu in cervical carcinogenesis.

A novel integrative risk index of papillary thyroid cancer progression combining genomic alterations and clinical factors

Although the majority of papillary thyroid cancer (PTC) is indolent, a subset of PTC behaves aggressively despite the best available treatment. A major clinical challenge is to reliably distinguish early on between those patients who need aggressive treatment from those who do not. Using a large cohort of PTC samples obtained from The Cancer Genome Atlas (TCGA), we analyzed the association between disease progression and multiple forms of genomic data, such as transcriptome, somatic mutations, and somatic copy number alterations, and found that genes related to FOXM1 signaling pathway were significantly associated with PTC progression. Integrative genomic modeling was performed, controlling for demographic and clinical characteristics, which included patient age, gender, TNM stages, histological subtypes, and history of other malignancy, using a leave-one-out elastic net model and 10-fold cross validation. For each subject, the model from the remaining subjects was used to determine the risk index, defined as a linear combination of the clinical and genomic variables from the elastic net model, and the stability of the risk index distribution was assessed through 2,000 bootstrap resampling. We developed a novel approach to combine genomic alterations and patient-related clinical factors that delineates the subset of patients who have more aggressive disease from those whose tumors are indolent and likely will require less aggressive treatment and surveillance (p = 4.62 × 10-10, log-rank test). Our results suggest that risk index modeling that combines genomic alterations with current staging systems provides an opportunity for more effective anticipation of disease prognosis and therefore enhanced precision management of PTC.

Expression of OTUB1 in hepatocellular carcinoma and its effects on HCC cell migration and invasion

OTUB1 (OTU domain-containing ubiquitin aldehyde binding protein 1) is a deubiquitinating enzyme (DUB) that belongs to the ovarian tumor (OTU) domain protease superfamily. Although it has been demonstrated to play important roles in the development of many kinds of cancer, the mechanism of OTUB1 in hepatocellular carcinoma (HCC) is not clear. The aim of this study was to explore the roles of OTUB1 in HCC progression using cell lines and 115 archived HCC samples. In addition, the clinical outcomes were also analyzed with a special focus on OTUB1 expression in HCC samples. In the immunohistochemical study, OTUB1 showed high expression in 60 of the 115 cases (52.2%). The OTUB1 expression level was significantly correlated with many clinicopathological parameters, including TNM stage (P = 0.002), histology stage (P = 0.002), and metastasis/recurrence (P = 0.016). Survival analysis showed that the group with OTUB1 overexpression had significantly shorter overall survival time than the group with OTUB1 downregulation (hazard ratio [HR] = 0.482; confidence interval [CI]: 0.311-0.748; P = 0.001). Multivariate analysis indicated that OTUB1 expression was a significant and independent prognostic parameter (HR = 0.214; CI: 0.126-0.364; P < 0.001) for HCC patients. The ability of HCC cells to undergo proliferation, migration, and invasion was suppressed by disruption of endogenous OTUB1 using short hairpin RNA (shRNA). OTUB1 expression appears to be a new and independent predictor for the prognosis of HCC patients. Overexpression of OTUB1 in HCC could be a novel, effective, and supplementary biomarker for HCC because it plays a vital role in the progression of HCC.

miR-542-3p inhibits colorectal cancer cell proliferation, migration and invasion by targeting OTUB1

Although miR-542-3p has been found to be aberrantly downregulated in variety of human tumors, little is known about its role in colorectal cancer (CRC). This study was designed to assess the prognostic value of miR-542-3p in CRC by examining the expression profile of miR-542-3p in patients with CRC and investigate the possible molecular mechanism underlying the function of miR-542-3p. Our results showed that low levels of miR-542-3p were significantly associated with advanced tumor stage and lymph node metastasis and miR-542-3p can serve as an independent prognostic marker for CRC. Furthermore, ectopic induced expression of miR-542-3p significantly suppressed cell proliferation, induced apoptosis, inhibited migration and invasion in vitro and in vivo. Mechanistically, we identified OTUB1 as a direct and functional target for miR-542-3p, at least partly responsible for the anti-tumor effect of miR-542-3p in CRC. Our study demonstrates the importance of miR-524-3p/OTUB1 signaling in CRC development and suggests that targeting this signaling may highlight a new therapeutic approach for treatment of CRC.

A Positive Feedback Loop of lncRNA-PVT1 and FOXM1 Facilitates Gastric Cancer Growth and Invasion

Purpose: The long, noncoding RNA (lncRNA) PVT1 is an important epigenetic regulator with a critical role in human tumors. Here, we aimed to investigate the clinical application and the potential molecular mechanisms of PVT1 in gastric cancer tumorigenesis and progression.Experimental Design: The expression level of PVT1 was determined by RT-qPCR analysis in 190 pairs of gastric cancer tissues and adjacent normal gastric mucosa tissues (ANT). The biologic functions of PVT1 were assessed by in vitro and in vivo functional experiments. RNA protein pull-down assays and LS/MS mass spectrometry analysis were performed to detect and identify the PVT1- interacting protein FOXM1. Protein-RNA immunoprecipitation assays were conducted to examine the interaction of FOXM1 and PVT1 Chromatin immunoprecipitation (ChIP) and luciferase analyses were utilized to identify the binding site of FOXM1 on the PVT1 promoter.Results: The lncRNA PVT1 was significantly upregulated in gastric cancer tissues compared with ANTs. High expression of PVT1 predicted poor prognosis in patients with gastric cancer. PVT1 enhanced gastric cancer cell proliferation and invasion in vitro and in vivoPVT1 directly bound FOXM1 protein and increased FOXM1 posttranslationally. Moreover, PVT1 is also a FOXM1-responsive lncRNA, and FOXM1 directly binds to the PVT1 promoter to activate its transcription. Finally, PVT1 fulfilled its oncogenic functions in a FOXM1-mediated manner.Conclusions: Our study suggests that PVT1 promotes tumor progression by interacting with FOXM1. PVT1 may be a valuable prognostic predictor for gastric cancer, and the positive feedback loop of PVT1-FOXM1 could be a therapeutic target in pharmacologic strategies. Clin Cancer Res; 23(8); 2071-80. ©2016 AACR.

DUBbing Cancer: Deubiquitylating Enzymes Involved in Epigenetics, DNA Damage and the Cell Cycle As Therapeutic Targets

Controlling cell proliferation is one of the hallmarks of cancer. A number of critical checkpoints ascertain progression through the different stages of the cell cycle, which can be aborted when perturbed, for instance by errors in DNA replication and repair. These molecular checkpoints are regulated by a number of proteins that need to be present at the right time and quantity. The ubiquitin system has emerged as a central player controlling the fate and function of such molecules such as cyclins, oncogenes and components of the DNA repair machinery. In particular, proteases that cleave ubiquitin chains, referred to as deubiquitylating enzymes (DUBs), have attracted recent attention due to their accessibility to modulation by small molecules. In this review, we describe recent evidence of the critical role of DUBs in aspects of cell cycle checkpoint control, associated DNA repair mechanisms and regulation of transcription, representing pathways altered in cancer. Therefore, DUBs involved in these processes emerge as potentially critical targets for the treatment of not only hematological, but potentially also solid tumors.