SENP2 regulates MMP13 expression in a bladder cancer cell line through SUMOylation of TBL1/TBLR1

Two decades of a protooncogene TBL1XR1: from a transcription modulator to cancer therapeutic target

Transducin beta-like 1X-related protein 1 (TBL1XR1) was discovered two decades ago and was implicated as part of the nuclear transcription corepressor complex. Over the past 20 years, the emerging oncogenic function of TBL1XR1 in cancer development has been discovered. Recent studies have highlighted that the genetic aberrations of TBL1XR1 in cancers, especially in hematologic tumors, are closely associated with tumorigenesis. In solid tumors, TBL1XR1 is proposed to be a promising prognostic biomarker due to the correlation between abnormal expression and clinicopathological parameters. Post-transcriptional and post-translational modification are responsible for the expression and function of TBL1XR1 in cancer. TBL1XR1 exerts its functional role in various processes that involves cell cycle and apoptosis, cell proliferation, resistance to chemotherapy and radiotherapy, cell migration and invasion, stemness and angiogenesis. Multitude of cancer-related signaling cascades like Wnt-β-catenin, PI3K/AKT, ERK, VEGF, NF-κB, STAT3 and gonadal hormone signaling pathways are tightly modulated by TBL1XR1. This review provided a comprehensive overview of TBL1XR1 in tumorigenesis, shedding new light on TBL1XR1 as a promising diagnostic biomarker and druggable target in cancer.

The emerging roles of SUMOylation in the tumor microenvironment and therapeutic implications

Tumor initiation, progression, and response to therapies depend to a great extent on interactions between malignant cells and the tumor microenvironment (TME), which denotes the cancerous/non-cancerous cells, cytokines, chemokines, and various other factors around tumors. Cancer cells as well as stroma cells can not only obtain adaption to the TME but also sculpt their microenvironment through a series of signaling pathways. The post-translational modification (PTM) of eukaryotic cells by small ubiquitin-related modifier (SUMO) proteins is now recognized as a key flexible pathway. Proteins involved in tumorigenesis guiding several biological processes including chromatin organization, DNA repair, transcription, protein trafficking, and signal conduction rely on SUMOylation. The purpose of this review is to explore the role that SUMOylation plays in the TME formation and reprogramming, emphasize the importance of targeting SUMOylation to intervene in the TME and discuss the potential of SUMOylation inhibitors (SUMOi) in ameliorating tumor prognosis.

Regulation and Function of Matrix Metalloproteinase-13 in Cancer Progression and Metastasis

Matrix metalloproteinase-13 (MMP-13) is a member of the Matrix metalloproteinases (MMPs) family of endopeptidases. MMP-13 is produced in low amounts and is well-regulated during normal physiological conditions. Its expression and secretion are, however, increased in various cancers, where it plays multiple roles in tumour progression and metastasis. As an interstitial collagenase, MMP-13 can proteolytically cleave not only collagens I, II and III, but also a range of extracellular matrix proteins (ECMs). Its action causes ECM remodelling and often leads to the release of various sequestered growth and angiogenetic factors that promote tumour cell growth, invasion and angiogenesis. This review summarizes our current understanding of the regulation of MMP-13 expression and secretion and discusses the actions of MMP-13 in cancer progression and metastasis.

SUMOylation Pattern Predicts Prognosis and Indicates Tumor Microenvironment Infiltration Characterization in Bladder Cancer

Background

SUMOylation is an important component of post-translational protein modifications (PTMs), and bladder cancer (BCa) is the ninth most common cancer around the world. But the comprehensive role of SUMOylation in shaping tumor microenvironment (TME) and influencing tumor clinicopathological features and also the prognosis of patients remains unclear.

Methods

Using the data downloaded from The Cancer Genome Atlas (TCGA) and the Gene Expression Omnibus (GEO), we comprehensively evaluated the SUMOylation patterns of 570 bladder cancer samples, and systematically correlated these SUMOylation patterns with TME immune cell infiltrating characteristics. The SUMO score was constructed to quantify SUMOylation patterns of individuals using principal component analysis (PCA) algorithms.

Results

Two distinct SUMOylation patterns and gene clusters were finally determined. Significant differences in the prognosis of patients were found among two different SUMOylation patterns and gene clusters, so were in the mRNA transcriptome and the landscape of TME immune cell infiltration. We also established a set of scoring system named SUMO score to quantify the SUMOylation pattern of individuals with BCa, which was discovered to be tightly connected with tumor clinicopathological characteristics and could predict the prognosis of patients with BCa. Moreover, SUMO score was a considerable predictive indicator for the survival outcome independent of tumor mutation burden (TMB) and low SUMO score was related to better response to immunotherapy using PD-1 blockade. We also found that there existed a significant relationship between sensitivity to commonly used chemotherapy drugs and SUMO score. Finally, a nomograph based on five features, namely, SUMO score, age, gender, T category, and M category was constructed to predict the survival probability of patients with BCa in 1, 3, and 5 years, respectively.

Conclusions

Our work demonstrated and overviewed the complicated regulation mechanisms of SUMOylation in bladder cancer, and better understanding and evaluating SUMOylation patterns could be helpful in guiding clinical therapeutic strategy and improving the prognosis of patients with BCa.

PPy@Fe3O4 Nanoparticles Inhibit Tumor Growth and Metastasis Through Chemodynamic and Photothermal Therapy in Non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is considered to be a principal cause of cancer death across the world, and nanomedicine has provided promising alternatives for the treatment of NSCLC in recent years. Photothermal therapy (PTT) and chemodynamic therapy (CDT) have represented novel therapeutic modalities for cancer treatment with excellent performance. The purpose of this research was to evaluate the effects of PPy@Fe₃O₄ nanoparticles (NPs) on inhibiting growth and metastasis of NSCLC by combination of PTT and CDT. In this study, we synthesized PPy@Fe₃O₄ NPs through a very facile electrostatic absorption method. And we detected reactive oxygen species production, cell apoptosis, migration and protein expression in different groups of A549 cells and established xenograft models to evaluate the effects of PPy@Fe₃O₄ NPs for inhibiting the growth of NSCLC. The results showed that the PPy@Fe₃O₄ NPs had negligible cytotoxicity and could efficiently inhibit the cell growth and metastasis of NSCLC in vitro. In addition, the PPy@Fe₃O₄ NPs decreased tumor volume and growth in vivo and endowed their excellent MRI capability of observing the location and size of tumor. To sum up, our study displayed that the PPy@Fe₃O₄ NPs had significant synergistic effects of PTT and CDT, and had good biocompatibility and safety in vivo and in vitro. The PPy@Fe₃O₄ NPs may be an effective drug platform for the treatment of NSCLC.

Intravesical High Dose BCG Tokyo and Low Dose BCG Tokyo with GMCSF+IFN α Induce Systemic Immunity in a Murine Orthotopic Bladder Cancer Model

This study evaluates a short therapy schedule for bladder cancer using BCG Tokyo. BCG Tokyo was evaluated in vitro using bone marrow derived dendritic cells, neutrophils, RAW macrophages and the murine bladder cancer cell line, MB49PSA, and compared to other BCG strains. BCG Tokyo > BCG TICE at inducing cytokine production. In vivo, high dose (1 × 10⁷ colony forming units (cfu)) and low dose (1 × 10⁶ cfu) BCG Tokyo with and without cytokine genes (GMCSF + IFNα) were evaluated in C57BL/6J mice (n = 12–16 per group) with orthotopically implanted MB49PSA cells. Mice were treated with four instillations of cytokine gene therapy and BCG therapy. Both high dose BCG alone and low dose BCG combined with cytokine gene therapy were similarly effective. In the second part the responsive groups, mice (n = 27) were monitored by urinary PSA analysis for a further 7 weeks after therapy cessation. More mice were cured at day 84 than at day 42 confirming activation of the immune system. Cured mice resisted the re-challenge with subcutaneous tumors unlike naïve, age matched mice. Antigen specific T cells recognizing BCG, HY and PSA were identified. Thus, fewer intravesical instillations, with high dose BCG Tokyo or low dose BCG Tokyo with GMCSF + IFNα gene therapy, can induce effective systemic immunity.

Regulation of transforming growth factor-β signalling by SUMOylation and its role in fibrosis

Fibrosis is an abnormal healing process that only repairs the structure of an organ after injury and does not address damaged functions. The pathogenesis of fibrosis is multifactorial and highly complex; numerous signalling pathways are involved in this process, with the transforming growth factor-β (TGF-β) signalling pathway playing a central role. TGF-β regulates the generation of myofibroblasts and the epithelial-mesenchymal transition by regulating transcription and translation of downstream genes and precisely regulating fibrogenesis. The TGF-β signalling pathway can be modulated by various post-translational modifications, of which SUMOylation has been shown to play a key role. In this review, we focus on the function of SUMOylation in canonical and non-canonical TGF-β signalling and its role in fibrosis, providing promising therapeutic strategies for fibrosis.

SENP Proteases as Potential Targets for Cancer Therapy

Simple Summary

Post-translational modification—the biochemical addition of functional groups or proteins—occurs following protein biosynthesis and contributes to an increase in the functional diversity of the proteome. Post-translational modifications include SUMOylation—the covalent attachment of small ubiquitin-related modifier (SUMO) proteins to substrate proteins. SUMOylation is a reversible modification, which is erased by SUMO-specific proteases (SENPs). Deregulation of SENPs leads to cellular dysfunction and is associated with various diseases, including cancer. The role of SENPs in cancer pathogenesis is expected, and thus these proteins are considered promising targets for drug design and development. In this review, we will discuss the role of SENPs, focusing on DNA repair and the cell cycle—cellular pathways malfunctioning in most cancer cells—and provide an update on advances in the development of SENP-oriented inhibitors.

Abstract

SUMOylation is a reversible post-translational modification (PTM) involving a covalent attachment of small ubiquitin-related modifier (SUMO) proteins to substrate proteins. SUMO-specific proteases (SENPs) are cysteine proteases with isopeptidase activity facilitating the de-conjugation of SUMO proteins and thus participating in maintaining the balance between the pools of SUMOylated and unSUMOylated proteins and in SUMO recycling. Several studies have reported that SENPs’ aberrant expression is associated with the development and progression of cancer. In this review, we will discuss the role of SENPs in the pathogenesis of cancer, focusing on DNA repair and the cell cycle—cellular pathways malfunctioning in most cancer cells. The plausible role of SENPs in carcinogenesis resulted in the design and development of their inhibitors, including synthetic protein-based, peptide-based, and small molecular weight inhibitors, as well as naturally occurring compounds. Computational methods including virtual screening have been implemented to identify a number of lead structures in recent years. Some inhibitors suppressed the proliferation of prostate cancer cells in vitro and in vivo, confirming that SENPs are suitable targets for anti-cancer treatment. Further advances in the development of SENP-oriented inhibitors are anticipated toward SENP isoform-specific molecules with therapeutic potential.

Identification of Key Genes Related to the Prognosis of Esophageal Squamous Cell Carcinoma Based on Chip Re-Annotation

Esophageal cancer (EC) is one of the deadliest cancers worldwide. However, reliable biomarkers for early diagnosis, or those for the prognosis of therapy, remain unfulfilled goals for its subtype esophageal squamous cell carcinoma (ESCC). The purpose of this study was to identify reliable biomarkers for the diagnosis and prognosis of ESCC by gene chip re-annotation technique and downstream bioinformatics analysis. In our research, the GSE53624 dataset was downloaded from the GEO database. Then, we reannotated the gene expression probe and obtained the gene expression matrix. Differential expressed genes (DEGs) were found by R packages and they were subjected to Gene Ontology enrichment analysis and protein–protein interaction (PPI) network construction. As a result, a total of 28,885 mRNA probes were reannotated, among which 210 down-regulated and 80 up-regulated DEGs were screened out. By combining these genes set in clinical prognosis information and Western blot analysis, we found four genes with diagnostic and prognostic significance, including MMP13, SPP1, MMP10, and COL1A1. Furthermore, markers of infiltrating immune cells exhibited different DEG-related immune infiltration patterns.

Comprehensive in silico analysis for identification of novel candidate target genes, including DHX36, OPA1, and SENP2, located on chromosome 3q in head and neck cancers

BACKGROUND

Major milestones of head and neck carcinogenesis have been associated with various genetic abnormalities; however, a clear picture of the molecular networks deregulated during the carcinogenesis of head and neck squamous cell carcinoma (HNSC) has not yet completely revealed.

METHODS

In this study, we used in silico tools and online data sets to evaluate the underlying reasons for the expressional changes of genes residing within the chromosome 3q and to help understanding their contributions to HNSC carcinogenesis.

RESULTS

We found that 13 of 20 most upregulated genes in HNSC are localized to 3q. Further analysis revealed a gene signature consisting of DHX36, OPA1, and SENP2, which showed significant correlation in HNSC samples and potentially be deregulated through similar mechanisms including DNA amplification, transcriptional, and posttranscriptional regulation.

CONCLUSIONS

Considering our findings, we suggest DHX36, OPA1, and SENP2 genes as overexpressed in HNSC tumors and that might be concurrently involved in HNSC carcinogenesis, tumor progression, and induction of angiogenic pathways.

Genetic alteration and clinical significance of SUMOylation regulators in multiple cancer types

The purpose of this study was to investigate the genetic variation, gene expression differences, and clinical significance of SUMOylation regulators in pan-cancers. Based on previous studies, we gained a better understanding of the biological process of SUMOylation and the status of current research. In the present study, we employed a wide range of bioinformatics methods. We used genetic variation and mRNA expression data in the Cancer Genome Atlas (TCGA) to construct a panoramic view of the single nucleotide variants, copy number variants, and gene expression changes in SUMOylation regulators in various tumors. Subsequently, we used the String website and the Cytoscape tool to construct the PPI network between these regulators. We used the GSCALite website to determine the relationship between these regulators and cancer pathways and drug sensitivity. We constructed images of co-expression between these regulators using the R programming language. Using clinical data from TCGA, we performed hazard ratio analysis for these regulators in pan-cancer. Most importantly, we used these regulators to successfully establish risk signatures related to patient prognosis in multiple tumors. Finally, in KIRC, we conducted gene-set enrichment analysis (GSEA) of the five molecules in its risk signatures. We found that these five molecules are involved in multiple cancer pathways. In short, we have comprehensively interpreted the detailed biological process of SUMOylation at the genetic level for the first time, successfully constructed multiple risk signatures, and conducted GSEA in KIRC. We believe that these findings provide credible and valuable information that is relevant for future clinical diagnoses and scientific research.

Identification of GOLM1 as a positively regulator of tumor metastasis by regulating MMP13 in gastric carcinoma

BACKGROUND

Metastatic gastric carcinoma (GC) is a typically incurable disease. The progression of anti-metastatic treatment is hampered because the underlying mechanisms regulating the metastasis of GC cell are not well illuminated.

OBJECTIVE

Therefore, further elucidation of the molecular mechanism behind the metastatic traits of GC cells is needed for optimizing GC treatment.

METHODS

The levels of GOLM1 and MMP13 in GC cells and tissues were measured by using qPCR assay. The growth of GC cells in vitro was detected using MTS and colony formation assays. The migration and invasion of GC cells was analyzed using wound healing test and Transwell invasion assay. The level of MMP13 in GC cell was measured using immunoblotting and the level of GOLM1 was measured using immunofluorescence staining. The role of GOLM1 on the distant metastasis of GC SGC7910 cell was analyzed using experimental metastasis assay. Transplanted tumor model was constructed to analyze the influence of GOLM1 on GC cell growth in vivo.

RESULTS

Here, we report that GOLM1 is over-expressed in GC and knockdown GOLM1 impairs the aggressive phenotypes of GC cell in vitro. Furthermore, downregulation of GOLM1 restrains the tumor growth of GC cell in nude mice. Nevertheless, upregulation of GOLM1 distinctly elevated the growth, migration ability and invasiveness of GC SGC7910 cell. Finally, GOLM1 increases the metastatic phenotypes of GC cell in a MMP13-dependent manner.

CONCLUSIONS

Altogether, this investigation demonstrates the crucial function of GOLM1 in the progression of GC, which indicating GOLM1 as a potential target for GC treatment.

Expression of SUMO associated proteins in the mouse endometrium is regulated by ovarian hormones throughout the estrous cycle

The modification of proteins by small ubiquitin-like modifier (SUMO), known as SUMOylation, regulates biological function by changing protein transcription and translation. During the estrous cycle the endometrium undergoes continual change to processes including cell proliferation, secretion and exfoliation and these changes are regulated by the levels of ovarian hormones. Increasing the expression of SUMO family members has previously been shown to promote proliferation and invasion of endometrial cancer cells. However, limited research has been carried out into the expression and function of SUMO in the mammalian endometrium. In the present study, the level and localization of SUMO-associated proteins throughout the natural estrous cycle in the mouse uterus was determined using immunohistochemical staining and western blot analysis. The association between the spatiotemporal expression of these SUMO modified proteins and SENPs in endometrium and the concentration of ovarian hormones during estrous cycle was revealed. The present study clarified the role of SUMOylation in maintenance of normal estrous cycling and may have important significance in the study of hormone-dependent endometrial diseases.

PIAS1 is not suitable as a urothelial carcinoma biomarker protein and pharmacological target

Urothelial cancer (UC) is one of the most common cancers in Europe and is also one of the costliest to treat. When first line therapies show initial success, around 50% of cancers relapse and proceed to metastasis. In this study we assessed the Protein inhibitor of activated signal transducers and activators of transcription (PIAS)1 as a potential therapeutic target in urothelial cancer. PIAS1 is a key regulator of STAT1 signalling and may be implicated in carcinogenesis. In contrast to other cancer types PIAS1 protein expression is not significantly different in malignant areas of UC specimens compared to non-malignant tissue. In addition, we found that down-regulation and overexpression of PIAS1 had no effect on the viability or colony forming ability of tested cell lines. Whilst other studies of PIAS1 suggest an important biological role in cancer, this study shows that PIAS1 has no influence on reducing the cytotoxic effects of Cisplatin or cell recovery after DNA damage induced by irradiation. Taken together, these in vitro data demonstrate that PIAS1 is not a promising therapeutic target in UC cancer as previously shown in different entities such as prostate cancer (PCa).

Regulation of post-translational modification in breast cancer treatment

The small ubiquitin-related modification molecule (SUMO), one of the post-translational modification molecules, is involved in a variety of cellular functions where it regulates protein activity and stability, transcription, and cell cycling. Modulation of protein SUMOylation or deSUMOylation modification has been associated with regulation of carcinogenesis in breast cancer. In the dynamic processes of SUMOylation and deSUMOylation in a variety of cancers, SUMO proteases (SENPs), reverse SUMOylation by isopeptidase activity and SENPs are mostly elevated, and are related to poor patient prognosis. Although underlying mechanisms have been suggested for how SENPs participate in breast cancer tumorigenesis, such as through regulation of target protein transactivation, cancer cell survival, cell cycle, or other post-translational modification-related machinery recruitment, the effect of SENP isoform-specific inhibitors on the progression of breast cancer have not been well evaluated. This review will introduce the functions of SENP1 and SENP2 and the underlying signaling pathways in breast cancer for use in discovery of new biomarkers for diagnosis or therapeutic targets for treatment. [BMB Reports 2019; 52(2): 113-118].

The deSUMOylase SENP2 coordinates homologous recombination and nonhomologous end joining by independent mechanisms

SUMOylation (small ubiquitin-like modifier) in the DNA double-strand break (DSB) response regulates recruitment, activity, and clearance of repair factors. However, our understanding of a role for deSUMOylation in this process is limited. Here we identify different mechanistic roles for deSUMOylation in homologous recombination (HR) and nonhomologous end joining (NHEJ) through the investigation of the deSUMOylase SENP2. We found that regulated deSUMOylation of MDC1 prevents excessive SUMOylation and its RNF4-VCP mediated clearance from DSBs, thereby promoting NHEJ. In contrast, we show that HR is differentially sensitive to SUMO availability and SENP2 activity is needed to provide SUMO. SENP2 is amplified as part of the chromosome 3q amplification in many cancers. Increased SENP2 expression prolongs MDC1 focus retention and increases NHEJ and radioresistance. Collectively, our data reveal that deSUMOylation differentially primes cells for responding to DSBs and demonstrates the ability of SENP2 to tune DSB repair responses.

Role of small ubiquitin-like modifier proteins-1 (SUMO-1) in regulating migration and invasion of fibroblast-like synoviocytes from patients with rheumatoid arthritis

Rheumatoid arthritis (RA) is featured by erosive cartilage and bone destruction. The enhancing aggressive property of fibroblast-like synoviocytes (FLSs) plays a critical role in this process. Small ubiquitin-like modifier (SUMO) proteins, including SUMO-1, SUMO-2, SUMO-3 and SUMO-4, participate in regulating many cellular events such as survival, migration and signal transduction in some cell lines. However, their roles in the pathogenesis of RA are not well established. Therefore, we evaluated the role of SUMO proteins in RA FLSs migration and invasion. We found that expression of both SUMO-1 and SUMO-2 was elevated in FLSs and synovial tissues (STs) from patients with RA. SUMO-1 suppression by small interference RNA (siRNA) reduced migration and invasion as well as MMP-1 and MMP-3 expression in RA FLSs. We also demonstrated that SUMO-1 regulated lamellipodium formation during cell migration. To explore further into molecular mechanisms, we evaluated the effect of SUMO-1 knockdown on the activation of Rac1/PAK1, a critical signaling pathway that controls cell motility. Our results indicated that SUMO-1-mediated SUMOylation controlled Rac1 activation and modulated downstream PAK1 activity. Inhibition of Rac1 or PAK1 also decreased migration and invasion of RA FLSs. Our findings suggest that SUMO-1 suppression could be protective against joint destruction in RA by inhibiting aggressive behavior of RA FLSs.

SENP2 exerts an anti‑tumor effect on chronic lymphocytic leukemia cells through the inhibition of the Notch and NF‑κB signaling pathways

Chronic lymphocytic leukemia (CLL) is one of the most often diagnosed hematological malignant tumors in the Western world and a type of inert B-cell lymphoma that commonly attacks the elderly. Small ubiquitin related modifier (SUMO)-specific protease 2 (SENP2) can act as a suppressor in various types of cancer by regulating the stability of β-catenin to affect the Notch signaling pathway; however, it has a low expression level in CLL cells. In this study, we firstly used western blot analysis and RT-qPCR to detect the protein and mRNA expression levels of SENP2 in the peripheral blood of patients with CLL and healthy volunteers. Secondly, we overexpressed or knocked down the expression of SENP2 in CLL cells and then determined the cell invasive and chemotactic ability in a Transwell assay and chemotaxis assay. We examined the sensitivity of the cells to cytarabine and dexamethasone via a CCK-8 assay and determined the cell apoptotic condition and the expression of the Notch signaling pathway using flow cytometry and western blot analysis. The results demonstrated that the patients with CLL had relatively low expression levels of SENP2. The overexpression of SENP2 in the CLL cells decreased their invasive and proliferative ability, as well as their chemotactic response and enhanced their sensitivity to cytarabine and dexamethasone, while it promoted cell apoptosis. The silencing of SENP2 in the CLL cells generally produced the opposite results. We thus hypothesized that the overexpression of SENP2 downregulated β-catenin expression, thus inhibiting the Notch signaling pathway in CLL cells. Moreover, the nuclear factor (NF)-κB signaling pathway was also regulated by the overexpression of SENP2. On the whole, the findings of this study indicate tha SENP2 can act as a tumor suppressor in CLL cells, and may thus prove to be a novel target for CLL treatment in clinical practice.

Post-translational modifications in bladder cancer: Expanding the tumor target repertoire

Over the past decade, genomic and transcriptomic analyses have uncovered promising tumor antigens including immunotherapeutic targets in bladder cancer (BCa). Conventional tumor antigens are proteins expressed on the plasma membrane of tumor cells such as EGFR, FGFR3, and ERBB2 in BCa, which can be targeted by antibodies or similar epitope-specific binding reagents. The cellular proteome consists of ∼100,000 proteins but the expression of these proteins is rarely unique to tumor cells. Many tumor-associated proteins are post-translationally modified with phosphorylation, glycosylation, ubiquitination, or SUMOylation moieties. Although these modifications expand the complexity, they potentially offer novel targeting opportunities across tumor sub-populations. Experimental targeting of cancer-specific post-translational modifications (PTMs) has shown encouraging results in pre-clinical models of BCa, which could potentially overcome issues with inherent intra-tumor heterogeneity due to simultaneous expression on different proteins. Here, we review current knowledge on post-translational modifications in BCa and highlight recent efforts in experimental targeting strategies.

The role of sentrin-specific protease 2 substrate recognition in TGF-β-induced tumorigenesis

Smad4, a common-mediator of Smads, plays a central role in forming complexes with receptor-phosphorylated Smads, and then transduces transforming growth factor (TGF)-β signals into the nuclei. Although many cellular factors are involved in TGF-β induced epithelial-to-mesenchymal transition (EMT) and cell migration, very little is known with the mechanism of Smad4 regulation on pro-oncogenes response by TGF-β. Herein, we demonstrate the interaction of Sentrin-specific protease 2 (SENP2) with Smad4 through SENP2 residue 363~400. The same segment is also important for desumoylation of Smad4, and able to relieve sumoylation-mediated TGF-β repression. The SENP2^363~400 segment is critical for TGF-β-induced cell migration, which is correlated with SENP2^363~400 deletion mutant failed to increase matrix metalloproteinase (MMP)-9 and EMT marker gene expression. Moreover, our results suggest that the interaction and desumoylation between SENP2 and Smad4 promote cell migration in triple-negative breast cancer cells. Altogether, our data show how SENP2 regulates its substrate for desumoylation, and also the role of SENP2 in TGF-β induced cancer cell migration.

SUMO1/sentrin/SMT3 specific peptidase 2 modulates target molecules and its corresponding functions

Small ubiquitin-like modifier (SUMOylation) is a reversible post-translational modification, which plays important roles in numerous biological processes. SUMO could be covalently attached to target proteins in an isopeptide bond manner that occurs via a lysine ε-amino group on the target proteins and the glycine on SUMO C-terminus. This covalent binding could affect the subcellular localization and stability of target proteins. SUMO modification can be reversed by members of the Sentrin/SUMO-specific proteases (SENPs) family, which are highly evolutionarily conserved from yeast to human. SENP2, a member of the SENPs family, mainly plays a physiological function in the nucleus. SENP2 can promote maturity of the SUMO and deSUMOylate for single-SUMO modified or poly-SUMO modified proteins. SENP2 can affect the related biological processes through its peptidase activity or the amino terminal transcriptional repression domain. It plays important roles by inhibiting or activating some molecular functions. Therefore, the research achievements of SENP2 are reviewed in order to understand its related functions and the underlying molecular mechanisms and provide a clue for future research on SENP2.

SENP2 alleviates CCl4-induced liver fibrosis by promoting activated hepatic stellate cell apoptosis and reversion

SUMOylation and deSUMOylation, a dynamic process, is proved to be involved in various fibrotic diseases. Here, we found SENP2, one of deSUMOylation protease family member, was decreased in CCl₄-induced mice fibrotic liver tissues, primary HSCs and restored after spontaneously recovery. In addition, HSC-T6 cells with TGF-β1 treatment resulted in a significant reduction of SENP2. Ectopic expression of SENP2 hindered cells activation and proliferation induced by TGF-β1 while knockdown of SENP2 showed an opposite effect. Importantly, SENP2 promoted apoptosis of HSC-T6 cells activated by TGF-β1. Furthermore, restoration of SENP2 was observed in inactivated HSCs after adipogenic differentiation mixture (MDI) treatment. Inadequate SENP2 inhibited the reversion of HSC-T6 cells, featured as aberrant expressions of α-SMA and col1a1, two markers of liver fibrosis. It has been reported SENP2 was a suppressant regulator of Wnt/β-catenin signal pathway. Similarly, we found SENP2 has a negative effect on β-catenin as well as its downstream genes C-myc and CyclinD1 in liver fibrosis. Collectively, our data indicated SENP2 may be involved in HSCs apoptosis and reversion in liver fibrosis.

CCR4 promotes metastasis via ERK/NF-κB/MMP13 pathway and acts downstream of TNF-α in colorectal cancer

Chemokines and chemokine receptors are causally involved in the metastasis of human malignancies. As a crucial chemokine receptor for mediating immune homeostasis, however, the role of CCR4 in colorectal cancer (CRC) remains unknown. In this study, we found that high expression of CCR4 in CRC tissues was correlated with shorter overall survival and disease free survival. In vitro and in vivo experiments revealed that silencing CCR4 attenuated the invasion and metastasis of CRC cells, whereas ectopic overexpression of CCR4 contributed to the forced metastasis of these cells. We further demonstrated that matrix metalloproteinase 13 (MMP13) played an important role in CCR4-mediated cancer cell invasion, which is up-regulated by ERK/NF-κB signaling. Positive correlation between CCR4 and MMP13 expression was also observed in CRC tissues. Moreover, our investigations showed that the level of CCR4 could be induced by TNF-α dependent of NF-κB activation in CRC cells. CCR4 might be implicated in TNF-α-regulated cancer cells metastasis. Combination of CCR4 and TNF-α is a more powerful prognostic marker for CRC patients. These findings suggest that CCR4 facilitates metastasis through ERK/NF-κB/MMP13 signaling and acts as a downstream target of TNF-α. CCR4 inhibition may be a promising therapeutic option for suppressing CRC metastasis.

The post-translational modification, SUMOylation, and cancer (Review)

SUMOylation is a reversible post-translational modification which has emerged as a crucial molecular regulatory mechanism, involved in the regulation of DNA damage repair, immune responses, carcinogenesis, cell cycle progression and apoptosis. Four SUMO isoforms have been identified, which are SUMO1, SUMO2/3 and SUMO4. The small ubiquitin-like modifier (SUMO) pathway is conserved in all eukaryotes and plays pivotal roles in the regulation of gene expression, cellular signaling and the maintenance of genomic integrity. The SUMO catalytic cycle includes maturation, activation, conjugation, ligation and de-modification. The dysregulation of the SUMO system is associated with a number of diseases, particularly cancer. SUMOylation is widely involved in carcinogenesis, DNA damage response, cancer cell proliferation, metastasis and apoptosis. SUMO can be used as a potential therapeutic target for cancer. In this review, we briefly outline the basic concepts of the SUMO system and summarize the involvement of SUMO proteins in cancer cells in order to better understand the role of SUMO in human disease.

Association between Sumoylation-Related Gene rs77447679 Polymorphism and Risk of Gastric Cancer (GC) in a Chinese Population

Purpose: Sumoylation plays a critical role in gene regulation and tumorigenesis, and is hypothesized to correlate with the development of various cancers. So far, there has been no reported association between sumoylation-related genes and the risk of gastric cancer (GC).

Methods: A total of 17 tagging single-nucleotide polymorphisms (tag-SNPs) in 5 sumoylation-related genes were selected and genotyped by SNaPshot in a case-control study, including 1021 GC patients and 1304 controls. Odds ratio (OR) and 95% confidential interval (CI) were computed to evaluate the genetic association of the onset of GC.

Results: We demonstrated that CBX4 rs77447679 polymorphism was significantly associated with GC risk (P= 0.017; adjusted OR: 1.71; 95% CI: 1.10-2.66). The patients with CC genotype had a lower risk of GC (CC vs. CA+AA, P= 0.017; adjusted OR: 1.24; 95% CI: 1.04-1.49).

Conclusion: This study revealed that CBX4 rs77447679 polymorphism was positively associated with GC, and individuals with CC genotype had less risk of GC. The risky effects and functional effect of this polymorphism in GC require further investigation.

Cordycepin induces apoptosis in human bladder cancer cells via activation of A3 adenosine receptors

Bladder cancer is a neoplasm originated from bladder epithelial cells. The therapy for bladder cancer is so far not satisfactory. In this study, we examined the effects of Cordyceps militaris hot water extracts containing cordycepin on human bladder cells. Cordyceps militaris hot water extracts containing cordycepin was used to treat human T24 bladder carcinoma cells, and we found that Cordyceps militaris hot water extracts containing cordycepin decreased T24 cell survival in a dose-dependent manner, which was seemingly mediated by activation of A3 adenosine receptor and the subsequent inactivation of Akt pathways, resulting in increases in cleaved Caspase-3 and apoptosis. Overexpression of A3 adenosine receptor in T24 cells mimicked the effects of Cordyceps militaris hot water extracts, while A3 adenosine receptor depletion abolished the effects of Cordyceps militaris hot water extracts containing cordycepin. Together, these data suggest that Cordyceps militaris hot water extracts containing cordycepin may be a promising treatment for bladder cancer via A3 adenosine receptor activation.

SENP2 suppresses epithelial-mesenchymal transition of bladder cancer cells through deSUMOylation of TGF-βRI

SUMO-specific protease 2 (SENP2) is a deSUMOylation protease that plays an important role in the regulation of transforming growth factor-β (TGF-β) signaling. Aberrant TGF-β signaling is common in human cancers and contributes to tumor metastasis by inducing an epithelial-mesenchymal transition (EMT). In previous studies, we demonstrated that SENP2 suppresses bladder cancer cell migration and invasion. However, little is known about whether SENP2 inhibits EMT by regulating TGF-β signaling in bladder cancer progression. Here, we investigated the role of SENP2 in regulating TGF-β signaling and bladder cancer metastasis in vitro and in vivo. We found that SENP2 is frequently downregulated in bladder cancer, especially in metastatic bladder cancer. SENP2 downregulation is associated with more aggressive phenotypes and poor patient outcomes. SENP2 knockdown results in a decrease of E-cadherin and an increase of N-cadherin and fibronectin at both transcript and protein levels, indicating that SENP2 negatively regulates EMT. On the contrary, SENP2 overexpression suppresses TGF-β signaling and TGF-β-induced EMT. We further demonstrated that SENP2 regulates TGF-β signaling partly through deSUMOylation of TGFβ receptor I (TGF-βRI). Functionally, SENP2 suppresses bladder cancer cell invasion in vitro and tumor metastasis in vivo, acts as a tumor suppressor gene in bladder cancer. Our results establish a function of SENP2 in metastatic progression and suggest its candidacy as a new prognostic biomarker and target for clinical management of bladder cancer.

Targeting nuclear thymidylate biosynthesis

Thymidylate (dTMP) biosynthesis plays an essential and exclusive function in DNA synthesis and proper cell division, and therefore has been an attractive therapeutic target. Folate analogs, known as antifolates, and nucleotide analogs that inhibit the enzymatic action of the de novo thymidylate biosynthesis pathway and are commonly used in cancer treatment. In this review, we examine the mechanisms by which the antifolate 5-fluorouracil, as well as other dTMP synthesis inhibitors, function in cancer treatment in light of emerging evidence that dTMP synthesis occurs in the nucleus. Nuclear localization of the de novo dTMP synthesis pathway requires modification of the pathway enzymes by the small ubiquitin-like modifier (SUMO) protein. SUMOylation is required for nuclear localization of the de novo dTMP biosynthesis pathway, and disruption in the SUMO pathway inhibits cell proliferation in several cancer models. We summarize evidence that the nuclear localization of the dTMP biosynthesis pathway is a critical factor in the efficacy of antifolate-based therapies that target dTMP synthesis.