Deubiquitinase USP20 promotes breast cancer metastasis by stabilizing SNAI2

USP5 promotes tumor progression by stabilizing SLUG in bladder cancer

Bladder cancer ranks as the second most prevalent urology malignancy globally. Invasive metastasis is a significant contributor to mortality among patients with bladder cancer, yet the underlying mechanisms remain elusive. Deubiquitinases are pivotal in carcinogenesis, with USP5 implicated in the malignant progression of hepatocellular carcinoma, colorectal cancer and non-small cell lung cancer. The present study assessed the role and mechanism of ubiquitin-specific proteinase 5 (USP5) in the malignant progression of bladder cancer. The association between USP5 expression and bladder cancer prognosis and stage was analyzed using The Cancer Genome Atlas database. Moreover, to elucidate the role of USP5 in bladder cancer, USP5 overexpression and knockdown cell lines were established using T24 cells. Cell viability, proliferation and migration were assessed using Cell Counting Kit-8, Transwell and scratch assays, respectively. Cyclohexanamide was used to evaluate the effect of USP5 expression on Snail family zinc finger 2 (SLUG) stability. Immunoprecipitation and immunofluorescence co-localization were utilized to probe the interaction between USP5 and SLUG. Changes in mRNA and protein levels were assessed using reverse transcription-quantitative PCR and western blotting, respectively. The results revealed that patients with bladder cancer with high USP5 expression had significantly shorter survival (P<0.05) and a higher clinicopathologic stage (P<0.05) than those with low USP5 expression. T24 cells overexpressing USP5 demonstrated significantly increased proliferation (P<0.05), invasion (P<0.05) and expression of epithelial-mesenchymal transition markers (P<0.05); whereas T24 cells with knocked-down USP5 expression revealed significantly reduced proliferation (P<0.05), invasion (P<0.05) and epithelial-mesenchymal transition markers (P<0.05). Immunoprecipitation experiments demonstrated the binding of USP5 to SLUG in bladder cancer cells, with further analysis revealing that USP5 upregulated protein levels of SLUG by inhibiting its ubiquitination. Furthermore, the treatment of bladder cancer cells with Degrasyn, a USP5 inhibitor, was associated with a significant inhibition of the proliferation (P<0.05) and invasion (P<0.05) of T24 cells. In conclusion, the findings of the present study underscore the role of USP5 in promoting the malignant progression of bladder cancer through the stabilization of SLUG. Targeting USP5 holds promise as a strategy for inhibiting bladder cancer progression.

Antiapoptotic and Prometastatic Roles of Cytokine FAM3B in Triple-Negative Breast Cancer

BACKGROUND

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. FAM3B, a secreted protein, has been extensively studied in various types of tumors. However, its function in breast cancer remains poorly understood.

METHODS

We analyzed FAM3B expression data from breast cancer patients available at TCGA database and overall survival was analyzed by using the Kaplan-Meier plotter. MDA-MB-231 TNBC tumor cell line and hormone-responsive MCF-7 cell lines were transfected to overexpress FAM3B. We assessed cell death, tumorigenicity, and invasiveness in vitro through MTT analysis, flow cytometry assays, anchorage-independent tumor growth, and wound healing assays, respectively. We performed in vivo evaluation by tumor xenograft in nude mice.

RESULTS

In silico analysis revealed that FAM3B expression was lower in all breast tumors. However, TNBC patients with high FAM3B expression had a poor prognosis. FAM3B overexpression protected MDA-MB-231 cells from cell death, with increased expression of Bcl-2 and Bcl-xL, and reduced caspase-3 activity. MDA-MB-231 cells overexpressing FAM3B also exhibited increased tumorigenicity and migration rates in vitro, displaying increased tumor growth and reduced survival rates in xenotransplanted nude mice. This phenotype is accompanied by the upregulation of EMT-related genes Slug, Snail, TGFBR2, vimentin, N-cadherin, MMP-2, MMP-9, and MMP-14. However, these effects were not observed in the MCF-7 cells overexpressing FAM3B.

CONCLUSION

FAM3B overexpression contributes to tumor growth, promotion of metastasis, and, consequently, leads to a poor prognosis in the most aggressive forms of breast cancer. Future clinical research is necessary to validate FAM3B as both a diagnostic and a therapeutic strategy for TNBC.

USP20 deubiquitinates and stabilizes the reticulophagy receptor RETREG1/FAM134B to drive reticulophagy

The endoplasmic reticulum (ER) serves as a hub for various cellular processes, and maintaining ER homeostasis is essential for cell function. Reticulophagy is a selective process that removes impaired ER subdomains through autophagy-mediatedlysosomal degradation. While the involvement of ubiquitination in autophagy regulation is well-established, its role in reticulophagy remains unclear. In this study, we screened deubiquitinating enzymes (DUBs) involved in reticulophagy and identified USP20 (ubiquitin specific peptidase 20) as a key regulator of reticulophagy under starvation conditions. USP20 specifically cleaves K48- and K63-linked ubiquitin chains on the reticulophagy receptor RETREG1/FAM134B (reticulophagy regulator 1), thereby stabilizing the substrate and promoting reticulophagy. Remarkably, despite lacking a transmembrane domain, USP20 is recruited to the ER through its interaction with VAPs (VAMP associated proteins). VAPs facilitate the recruitment of early autophagy proteins, including WIPI2 (WD repeat domain, phosphoinositide interacting 2), to specific ER subdomains, where USP20 and RETREG1 are enriched. The recruitment of WIPI2 and other proteins in this process plays a crucial role in facilitating RETREG1-mediated reticulophagy in response to nutrient deprivation. These findings highlight the critical role of USP20 in maintaining ER homeostasis by deubiquitinating and stabilizing RETREG1 at distinct ER subdomains, where USP20 further recruits VAPs and promotes efficient reticulophagy.Abbreviations: ACTB actin beta; ADRB2 adrenoceptor beta 2; AMFR/gp78 autocrine motility factor receptor; ATG autophagy related; ATL3 atlastin GTPase 3; BafA1 bafilomycin A1; BECN1 beclin 1; CALCOCO1 calcium binding and coiled-coil domain 1; CCPG1 cell cycle progression 1; DAPI 4',6-diamidino-2-phenylindole; DTT dithiothreitol; DUB deubiquitinating enzyme; EBSS Earle's Balanced Salt Solution; FFAT two phenylalanines (FF) in an acidic tract; GABARAP GABA type A receptor-associated protein; GFP green fluorescent protein; HMGCR 3-hydroxy-3-methylglutaryl-CoA reductase; IL1B interleukin 1 beta; LIR LC3-interacting region; MAP1LC3/LC3 microtubule associated protein 1 light chain 3; PIK3C3/Vps34 phosphatidylinositol 3-kinase catalytic subunit type 3; RB1CC1/FIP200 RB1 inducible coiled-coil 1; RETREG1/FAM134B reticulophagy regulator 1; RFP red fluorescent protein; RHD reticulon homology domain; RIPK1 receptor interacting serine/threonine kinase 1; RTN3L reticulon 3 long isoform; SEC61B SEC61 translocon subunit beta; SEC62 SEC62 homolog, preprotein translocation factor; SIM super-resolution structured illumination microscopy; SNAI2 snail family transcriptional repressor 2; SQSTM1/p62 sequestosome 1; STING1/MITA stimulator of interferon response cGAMP interactor 1; STX17 syntaxin 17; TEX264 testis expressed 264, ER-phagy receptor; TNF tumor necrosis factor; UB ubiquitin; ULK1 unc-51 like autophagy activating kinase 1; USP20 ubiquitin specific peptidase 20; USP33 ubiquitin specific peptidase 33; VAMP8 vesicle associated membrane protein 8; VAPs VAMP associated proteins; VMP1 vacuole membrane protein 1; WIPI2 WD repeat domain, phosphoinositide interacting 2; ZFYVE1/DFCP1 zinc finger FYVE-type containing 1.

Emerging roles of deubiquitinating enzymes in actin cytoskeleton and tumor metastasis

BACKGROUND

Metastasis accounts for the majority of cancer-related deaths. Actin dynamics and actin-based cell migration and invasion are important factors in cancer metastasis. Metastasis is characterized by actin polymerization and depolymerization, which are precisely regulated by molecular changes involving a plethora of actin regulators, including actin-binding proteins (ABPs) and signalling pathways, that enable cancer cell dissemination from the primary tumour. Research on deubiquitinating enzymes (DUBs) has revealed their vital roles in actin dynamics and actin-based migration and invasion during cancer metastasis.

CONCLUSION

Here, we review how DUBs drive tumour metastasis by participating in actin rearrangement and actin-based migration and invasion. We summarize the well-characterized and essential actin cytoskeleton signalling molecules related to DUBs, including Rho GTPases, Src kinases, and ABPs such as cofilin and cortactin. Other DUBs that modulate actin-based migration signalling pathways are also discussed. Finally, we discuss and address therapeutic opportunities and ongoing challenges related to DUBs with respect to actin dynamics.

The deubiquitinating enzyme USP4 regulates BRCA1 stability and function

BRCA1 plays a suppressive role in breast tumorigenesis. Ubiquitin-dependent degradation is a common mechanism that regulates BRCA1 protein stability, and several ubiquitin ligases involved have been identified. However, the deubiquitinating enzyme for BRCA1 remains less defined. Here, we report that the deubiquitinase USP4 interacts with, deubiquitinates and stabilizes BRCA1, maintaining the protein level of BRCA1. USP4 knockdown results in a decreased BRCA1 protein level, impairment in homologous recombination mediated double-stranded break repair, and increased genome instability, and confers resistance to DNA damage-inducing agents and PARP inhibitors. Ectopic expression of USP4 stabilizes BRCA1 and reverse the effects caused by USP4 knockdown. Moreover, USP4 is low expressed in human breast cancer tissues and its low expression correlates with poorer survival of patients. Furthermore, we identified several loss-of-function mutations of USP4 in human gynecological cancers, the catalytic activity of which or their interaction with BRCA1 is disrupted. Together, we reveal that USP4 is a deubiquitinase for BRCA1. USP4 positively regulates the stability and function of BRCA1 through de-ubiquitination, and plays important role in the suppression of breast cancer.

The deubiquitinase USP7 and E3 ligase TRIM21 regulate vasculogenic mimicry and malignant progression of RMS by balancing SNAI2 homeostasis

BACKGROUND

Rhabdomyosarcoma (RMS) is a rare malignancy and the most common soft tissue sarcoma in children. Vasculogenic mimicry (VM) is a novel tumor microcirculation model different from traditional tumor angiogenesis, which does not rely on endothelial cells to provide sufficient blood supply for tumor growth. In recent years, VM has been confirmed to be closely associated with tumor progression. However, the ability of RMS to form VM has not yet been reported.

METHODS

Immunohistochemistry, RT-qPCR and western blot were used to test the expression level of SNAI2 and its clinical significance. The biological function in regulating vasculogenic mimicry and malignant progression of SNAI2 was examined both in vitro and in vivo. Mass spectrometry, co-immunohistochemistry, immunofluorescence staining, and ubiquitin assays were performed to explore the regulatory mechanism of SNAI2.

RESULTS

Our study indicated that SNAI2 was abnormally expressed in patients with RMS and RMS cell lines and promoted the proliferation and metastasis of RMS. Through cell tubule formation experiments, nude mice Matrigel plug experiments, and immunohistochemistry (IHC), we confirmed that RMS can form VM and that SNAI2 promotes the formation of VM. Due to SNAI2 is a transcription factor that is not easily drugged, we used Co-IP combined with mass spectrometry to screen for the SNAI2-binding protein USP7 and TRIM21. USP7 depletion inhibited RMS VM formation, proliferation and metastasis by promoting SNAI2 degradation. We further demonstrated that TRIM21 is expressed at low levels in human RMS tissues and inhibits VM in RMS cells. TRIM21 promotes SNAI2 protein degradation through ubiquitination in the RMS. The deubiquitinase USP7 and E3 ligase TRIM21 function in an antagonistic rather than competitive mode and play a key role in controlling the stability of SNAI2 to determine the VM formation and progression of RMS.

CONCLUSION

Our findings reveal a previously unknown mechanism by which USP7 and TRIM21 balance the level of SNAI2 ubiquitination, determining RMS vasculogenic mimicry, proliferation, and migration. This new mechanism may provide new targeted therapies to inhibit the development of RMS by restoring TRIM21 expression or inhibiting USP7 expression in RMS patients with high SNAI2 protein levels.

Dysregulation of deubiquitination in breast cancer

Breast cancer (BC) is a highly frequent malignant tumor that poses a serious threat to women's health and has different molecular subtypes, histological subtypes, and biological features, which act by activating oncogenic factors and suppressing cancer inhibitors. The ubiquitin-proteasome system (UPS) is the main process contributing to protein degradation, and deubiquitinases (DUBs) are reverse enzymes that counteract this process. There is growing evidence that dysregulation of DUBs is involved in the occurrence of BC. Herein, we review recent research findings in BC-associated DUBs, describe their nature, classification, and functions, and discuss the potential mechanisms of DUB-related dysregulation in BC. Furthermore, we present the successful treatment of malignant cancer with DUB inhibitors, as well as analyzing the status of targeting aberrant DUBs in BC.

A novel PDIA3/FTO/USP20 positive feedback regulatory loop induces osteogenic differentiation of preosteoblast in osteoporosis

Osteoporosis is a chronic skeletal disease and the major source of risk for fractures in aged people. It is urgent to investigate the mechanism regulating osteoporosis for developing potential treatment and prevention strategies. Osteogenic differentiation of preosteoblast enhances bone formation, which might be a promising strategy for treatment and prevention of osteoporosis. Protein disulfide isomerase family A, member 3 (PDIA3) could induce bone formation, yet the role of PDIA3 in osteogenic differentiation of preosteoblast remains unknown. In this study, m6 A RNA methylation was detected by methylated RNA immunoprecipitation (MeRIP), while mRNA stability was identified by RNA decay assay. Besides, protein-protein interaction and protein phosphorylation were determined using co-immunoprecipitation (Co-IP). Herein, results revealed that PDIA3 promoted osteogenic differentiation of preosteoblast MC3T3-E1. Besides, PDIA3 mRNA methylation was suppressed by FTO alpha-ketoglutarate dependent dioxygenase (FTO) as RNA methylation reduced PDIA3 mRNA stability during osteogenic differentiation of MC3T3-E1 cells. Moreover, ubiquitin specific peptidase 20 (USP20) improved FTO level through inhibiting FTO degradation while PDIA3 increased FTO level by enhancing USP20 phosphorylation during osteogenic differentiation of MC3T3-E1 cells, suggesting a positive feedback regulatory loop between PDIA3 and FTO. In summary, these findings indicated the mechanism of PDIA3 regulating osteogenic differentiation of preosteoblast and provided potential therapeutic targets for osteoporosis.

The Emerging Role of Deubiquitinases in Radiosensitivity

Radiation therapy is a primary treatment for cancer, but radioresistance remains a significant challenge in improving efficacy and reducing toxicity. Accumulating evidence suggests that deubiquitinases (DUBs) play a crucial role in regulating cell sensitivity to ionizing radiation. Traditional small-molecule DUB inhibitors have demonstrated radiosensitization effects, and novel deubiquitinase-targeting chimeras (DUBTACs) provide a promising strategy for radiosensitizer development by harnessing the ubiquitin-proteasome system. This review highlights the mechanisms by which DUBs regulate radiosensitivity, including DNA damage repair, the cell cycle, cell death, and hypoxia. Progress on DUB inhibitors and DUBTACs is summarized, and their potential radiosensitization effects are discussed. Developing drugs targeting DUBs appears to be a promising alternative approach to overcoming radioresistance, warranting further research into their mechanisms.

Targeting SMAD-Dependent Signaling: Considerations in Epithelial and Mesenchymal Solid Tumors

SMADs are the canonical intracellular effector proteins of the TGF-β (transforming growth factor-β). SMADs translocate from plasma membrane receptors to the nucleus regulated by many SMAD-interacting proteins through phosphorylation and other post-translational modifications that govern their nucleocytoplasmic shuttling and subsequent transcriptional activity. The signaling pathway of TGF-β/SMAD exhibits both tumor-suppressing and tumor-promoting phenotypes in epithelial-derived solid tumors. Collectively, the pleiotropic nature of TGF-β/SMAD signaling presents significant challenges for the development of effective cancer therapies. Here, we review preclinical studies that evaluate the efficacy of inhibitors targeting major SMAD-regulating and/or -interacting proteins, particularly enzymes that may play important roles in epithelial or mesenchymal compartments within solid tumors.

USP30 promotes the progression of breast cancer by stabilising Snail

Breast cancer (BC) is the most prevalent tumour in women worldwide. USP30 is a deubiquitinase that has been previously reported to promote tumour progression and lipid synthesis in hepatocellular carcinoma. However, the role of USP30 in breast cancer remains unclear. Therefore, we investigated its biological action and corresponding mechanisms in vitro and in vivo. In our study, we found that USP30 was highly expressed in breast cancer samples and correlated with a poor patient prognosis. Knockdown of USP30 significantly suppressed the proliferation, invasion and migration abilities of BC cells in vitro and tumour growth in vivo, whereas overexpression of USP30 exhibited the opposite effect. Mechanistically, we verified that USP30 interacts with and stabilises Snail to promote its protein expression through deubiquitination by K48-linked polyubiquitin chains and then accelerates the EMT program. More importantly, USP30 reduced the chemosensitivity of BC cells to paclitaxel (PTX). Collectively, these data demonstrate that USP30 promotes the BC cell EMT program by stabilising Snail and attenuating chemosensitivity to PTX and may be a potential therapeutic target in BC.

Helicobacter pylori promotes gastric fibroblast proliferation and migration by expulsing exosomal miR-124-3p

Gastric fibroblasts (GFs) are direct targets of Helicobacter pylori (H. pylori). GFs infected with H. pylori exhibit marked changes in their morphology and biological behavior. However, the molecular mechanisms by which H. pylori regulates GFs remain unknown. In this study, we cocultured GFs with H. pylori for 48 h. As a result, GFs exhibited an elongated and spindle-shaped morphology. Further, cancer-associated fibroblast (CAF) biomarkers were increased, and related behaviors were significantly enhanced in H. pylori-activated GFs. The number of extracellular vesicles (EVs) secreted by H. pylori-activated GFs remarkably increased. The miR-124-3p level was increased in secreted EVs but decreased in the cytoplasm of H. pylori-activated GFs. Overexpression of miRNA-124-3p in the original GFs significantly suppressed their proliferation and migration. In addition, the migration-promoting effects of H. pylori-activated GFs were suppressed by miR-124-3p and GW4869, which blocked EV generation. Finally, pull-down and luciferase assays revealed that SNAI2 is a target of miR-124-3p. The migration-inhibitory effects of GFs treated with miR-124-3p were eliminated by the overexpression of SNAI2, and the upregulation of SNAI2 in H. pylori-activated GFs was partially alleviated by miR-124-3p or GW4869. Overall, H. pylori infection promotes the proliferation and migration of GFs by accelerating the expulsion of EVs carrying miRNA-124-3p, a SNAI2 inhibitor.

Identification of signature of tumor-infiltrating CD8 T lymphocytes in prognosis and immunotherapy of colon cancer by machine learning

BACKGROUND

To explore the specific marker of CD8+ T cell subsets which are closely related to the prognosis and immunotherapy of patients with colon cancer.

METHODS

18 kinds of immune cell expression profile data sets were obtained from GEO database. Compared with other immune cell types, the specific markers of CD8 (+) T cells (TI-CD8) in colorectal cancer were screened. Regression analyses were used to further screen prognostic related genes and construct a prognostic evaluation model. The patients were stratified and analyzed according to the risk scores, KRAS mutation status, stage, lymphatic infiltration and other indicators. The landscape of infiltration level, mutation and copy number variation of immune subsets in high and low TI-CD8Sig score groups were compared and analyzed. The difference of drug response between high and low TI-CD8Sig score groups was analyzed. Differential expression of the model genes was verified by the HPA database.

RESULTS

Six prognostic-related CD8T cell-specific gene targets were further screened, and the prognostic evaluation model was constructed. The AUC value of the model is >0.75. FAT3 and UNC13C showed a high mutation state in the low-risk group, while USH2A, MUC5B et al. specifically showed a high mutation state in the high-risk group. Compared with the low-risk group, the high-risk group had lower effective rate of drug response. The expression of PD-1 gene was positively correlated with the level of TI-CD8Sig score.

CONCLUSION

The risk assessment model based on CD8T cell-specific marker genes can effectively predict the prognosis and the drug response of patients with CRC.

ATR-dependent ubiquitin-specific protease 20 phosphorylation confers oxaliplatin and ferroptosis resistance

Oxaliplatin (OXA) resistance is a major clinic challenge in hepatocellular carcinoma (HCC). Ferroptosis is a kind of iron-dependent cell death. Triggering ferroptosis is considered to restore sensitivity to chemotherapy. In the present study, we found that USP20 was overexpressed in OXA-resistant HCC cells. High expression of USP20 in HCC was associated with poor prognosis. USP20 contributes OXA resistance and suppress ferroptosis in HCC. Pharmacological inhibition or knockdown of USP20 triggered ferroptosis and increased the sensitivity of HCC cells to OXA both in vitro and in vivo. Coimmunoprecipitation results revealed that the UCH domain of USP20 interacted with the N terminal of SLC7A11. USP20 stabilized SLC7A11 via removing K48-linked polyubiquitination of SLC7A11 protein at K30 and K37. Most importantly, DNA damage-induced ATR activation was required for Ser132 and Ser368 phosphorylation of USP20. USP20 phosphorylation at Ser132 and Ser368 enhanced its stability and thus conferred OXA and ferroptosis resistance of HCC cells. Our study reveals a previously undiscovered association between OXA and ferroptosis and provides new insight into mechanisms regarding how DNA damage therapies always lead to therapeutic resistance. Therefore, targeting USP20 may mitigate the development of drug resistance and promote ferroptosis of HCC in patients receiving chemotherapy.

Long Noncoding RNA MIAT Modulates Chronic Retinal Ischemia-Reperfusion Injury in Mice via the microRNA-203-3p/SNAI2 Axis

Retinal ischemia-reperfusion injury (RIRI) is a vital pathological process of multiple ocular diseases. This study aimed at investigating the effects of the MIAT/miR-203-3p/SNAI2 axis on RIRI. RIRI was produced by inducing an exceedingly high intraocular pressure (IOP) in mice. Mouse retinal ganglion cells (RGCs) were subjected to oxygen-glucose deprivation/reoxygenation (OGD/R) to mimic in vitro models. Relevant oligonucleotides or plasmids were transfected into OGD/R-induced RGCs in vitro or injected into RIRI mice models in vivo via a vitreous cavity. The findings of our paper indicated that MIAT and SNAI2 were highly expressed and miR-203-3p was lowly expressed in mouse RIRI tissues and OGD/R-induced RGCs. Interfering MIAT promoted the viability of OGD/R-induced RGCs, decreased apoptosis, and reduced oxidative stress in vitro. Silencing MIAT increased retinal neuronal cell numbers and decreased retinal neuronal cell apoptosis in mouse RIRI tissues in vivo. MIAT sponged miR-203-3p, and miR-203-3p targeted and inhibited SNAI2 expression. SNAI2 up-regulation or miR-203-3p down-regulation reversed the protective effects of MIAT down-regulation on RIRI in mice and OGD/R-induced RGCs. MIAT sponges miR-203-3p upregulated the expression of SNAI2, thereby promoting RIRI in mice. In summary, MIAT may be a therapeutic target for the treatment of chronic RIRI.

NUAK1 promotes tumor metastasis through upregulating slug transcription in esophageal squamous cell carcinoma

BACKGROUND

Metastasis is still a major cause of poor pathological outcome and prognosis in esophageal squamous cell carcinoma (ESCC) patients. NUAK1 has been reported highly expressed in many human cancers and is associated with the poor prognosis of cancer patients. However, the role of NUAK1 and its underlying signaling mechanism in ESCC metastasis remain unclear.

METHODS

Expression of NUAK1 in ESCC was detected by real-time quantitative RT-PCR (qRT-PCR), Western blotting and immunohistochemical staining. MTT, colony formation, wound-healing and transwell assays were used to determine the role NUAK1 in vitro. Metastasis was evaluated by use of an experimental pulmonary metastasis model in BALB/c-nu/nu mice. The mechanisms were assessed by using coimmunoprecipitation, immunofluorescence and dual-luciferase reporter gene experiments.

RESULTS

NUAK1 was highly expressed in ESCC tissues compared with the adjacent normal esophageal epithelial tissues. Moreover, the elevated expression of NUAK1 positively correlated with tumor invasion depth, lymph node metastasis, pathological TNM stage, and poor survival in ESCC patients. Further experiments showed that NUAK1 overexpression did not change the cell viability and colony formation of ESCC cells, while remarkably promoted the migration and invasion in vitro and experimental pulmonary metastasis in vivo. Mechanistically, NUAK1 enhanced the transcription level of Slug, which enhanced the migratory and invasive capability of ESCC cells. Consistently, silencing Slug almost completely diminished the migration and invasion of NUAK1-overexpressing ESCC cells. Further studies demonstrated that NUAK1 upregulated the transcription activity of Slug through activating the JNK/c-Jun pathway.

CONCLUSION

These results demonstrated that NUAK1 promoted the metastasis of ESCC cells through activating JNK/c-Jun/Slug signaling, indicating NUAK1 is a promising therapeutic target for metastatic ESCC.

Upregulation of LINC00501 by H3K27 acetylation facilitates gastric cancer metastasis through activating epithelial-mesenchymal transition and angiogenesis

BACKGROUND

The molecular mechanism of the significant role of long noncoding RNAs (lncRNAs) in the progression and metastasis of gastric cancer (GC) remains largely elusive. Our objective is to detect overexpressed lncRNA in GC and investigate its role in promoting epithelial-mesenchymal transition and tumour microenvironment remodel.

METHODS

LncRNA differential expression profile in GC was analysed using RNA microarrays. The level of LINC00501 was evaluated in both GC patient tissues and GC cell lines by quantitative reverse transcription PCR and large-scale (n = 304) tissue microarray. To explore the biological role and regulatory driver of LINC00501 in GC, various experimental techniques including Chromatin isolation by RNA purification (ChIRP), RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP) assay, dual luciferase assays were performed.

RESULTS

Clinically, it was observed that LINC00501 level was abnormal overexpression in GC tissue and was associated with GC progression and distant metastasis. Gain and loss molecular biological experiments suggested that LINC00501, promoted EMT process and angiogenesis of GC. Mechanically, the enrichment of H3K27 acetylation in LINC00501 promoter region contributed to the increase of LINC00501 in GC. LINC00501 transactivated transcription of SLUG, by recruiting hnRNPR to its promoter. The growth of GC was inhibited both in vitro and in vivo by suppressing the level of LINC00501 using pharmacological intervention from the histone acetyltransferase (HAT) inhibitor -C646.

CONCLUSIONS

This study suggests that LINC00501 promotes GC progression via hnRNPR/SLUG pathway, which indicates a promising biomarker and target for GC.

USP32 deubiquitinase: cellular functions, regulatory mechanisms, and potential as a cancer therapy target

An essential protein regulatory system in cells is the ubiquitin-proteasome pathway. The substrate is modified by the ubiquitin ligase system (E1-E2-E3) in this pathway, which is a dynamic protein bidirectional modification regulation system. Deubiquitinating enzymes (DUBs) are tasked with specifically hydrolyzing ubiquitin molecules from ubiquitin-linked proteins or precursor proteins and inversely regulating protein degradation, which in turn affects protein function. The ubiquitin-specific peptidase 32 (USP32) protein level is associated with cell cycle progression, proliferation, migration, invasion, and other cellular biological processes. It is an important member of the ubiquitin-specific protease family. It is thought that USP32, a unique enzyme that controls the ubiquitin process, is closely linked to the onset and progression of many cancers, including small cell lung cancer, gastric cancer, breast cancer, epithelial ovarian cancer, glioblastoma, gastrointestinal stromal tumor, acute myeloid leukemia, and pancreatic adenocarcinoma. In this review, we focus on the multiple mechanisms of USP32 in various tumor types and show that USP32 controls the stability of many distinct proteins. Therefore, USP32 is a key and promising therapeutic target for tumor therapy, which could provide important new insights and avenues for antitumor drug development. The therapeutic importance of USP32 in cancer treatment remains to be further proven. In conclusion, there are many options for the future direction of USP32 research.

Emerging role of deubiquitination modifications of programmed death-ligand 1 in cancer immunotherapy

Immune evasion is essential for carcinogenesis and cancer progression. Programmed death-ligand 1 (PD-L1), a critical immune checkpoint molecule, interacts with programmed death receptor-1 (PD-1) on immune cells to suppress anti-tumor immune responses. In the past decade, antibodies targeting PD-1/PD-L1 have tremendously altered cancer treatment paradigms. Post-translational modifications have been reported as key regulators of PD-L1 expression. Among these modifications, ubiquitination and deubiquitination are reversible processes that dynamically control protein degradation and stabilization. Deubiquitinating enzymes (DUBs) are responsible for deubiquitination and have emerged as crucial players in tumor growth, progression, and immune evasion. Recently, studies have highlighted the participation of DUBs in deubiquitinating PD-L1 and modulating its expression. Here, we review the recent developments in deubiquitination modifications of PD-L1 and focus on the underlying mechanisms and effects on anti-tumor immunity.

The ubiquitin-proteasome system in breast cancer

Ubiquitin-proteasome system (UPS) is a selective proteolytic system that is associated with the expression or function of target proteins and participates in various physiological and pathological processes of breast cancer. Inhibitors targeting the 26S proteasome in combination with other drugs have shown promising therapeutic effects in the clinical treatment of breast cancer. Moreover, several inhibitors/stimulators targeting other UPS components are also effective in preclinical studies, but have not yet been applied in the clinical treatment of breast cancer. Therefore, it is vital to comprehensively understand the functions of ubiquitination in breast cancer and to identify potential tumor promoters or tumor suppressors among UPS family members, with the aim of developing more effective and specific inhibitors/stimulators targeting specific components of this system.

Dissecting metastasis using preclinical models and methods

Metastasis has long been understood to lead to the overwhelming majority of cancer-related deaths. However, our understanding of the metastatic process, and thus our ability to prevent or eliminate metastases, remains frustratingly limited. This is largely due to the complexity of metastasis, which is a multistep process that likely differs across cancer types and is greatly influenced by many aspects of the in vivo microenvironment. In this Review, we discuss the key variables to consider when designing assays to study metastasis: which source of metastatic cancer cells to use and where to introduce them into mice to address different questions of metastasis biology. We also examine methods that are being used to interrogate specific steps of the metastatic cascade in mouse models, as well as emerging techniques that may shed new light on previously inscrutable aspects of metastasis. Finally, we explore approaches for developing and using anti-metastatic therapies, and how mouse models can be used to test them.

Bayesian Machine Learning Enables Identification of Transcriptional Network Disruptions Associated with Drug-Resistant Prostate Cancer

Survival rates of patients with metastatic castration-resistant prostate cancer (mCRPC) are low due to lack of response or acquired resistance to available therapies, such as abiraterone (Abi). A better understanding of the underlying molecular mechanisms is needed to identify effective targets to overcome resistance. Given the complexity of the transcriptional dynamics in cells, differential gene expression analysis of bulk transcriptomics data cannot provide sufficient detailed insights into resistance mechanisms. Incorporating network structures could overcome this limitation to provide a global and functional perspective of Abi resistance in mCRPC. Here, we developed TraRe, a computational method using sparse Bayesian models to examine phenotypically driven transcriptional mechanistic differences at three distinct levels: transcriptional networks, specific regulons, and individual transcription factors (TF). TraRe was applied to transcriptomic data from 46 patients with mCRPC with Abi-response clinical data and uncovered abrogated immune response transcriptional modules that showed strong differential regulation in Abi-responsive compared with Abi-resistant patients. These modules were replicated in an independent mCRPC study. Furthermore, key rewiring predictions and their associated TFs were experimentally validated in two prostate cancer cell lines with different Abi-resistance features. Among them, ELK3, MXD1, and MYB played a differential role in cell survival in Abi-sensitive and Abi-resistant cells. Moreover, ELK3 regulated cell migration capacity, which could have a direct impact on mCRPC. Collectively, these findings shed light on the underlying transcriptional mechanisms driving Abi response, demonstrating that TraRe is a promising tool for generating novel hypotheses based on identified transcriptional network disruptions.

SIGNIFICANCE

The computational method TraRe built on Bayesian machine learning models for investigating transcriptional network structures shows that disruption of ELK3, MXD1, and MYB signaling cascades impacts abiraterone resistance in prostate cancer.

USP25 Ameliorates Pathological Cardiac Hypertrophy by Stabilizing SERCA2a in Cardiomyocytes

BACKGROUND

Pathological cardiac hypertrophy can lead to heart failure and is one of the leading causes of death globally. Understanding the molecular mechanism of pathological cardiac hypertrophy will contribute to the treatment of heart failure. DUBs (deubiquitinating enzymes) are essential to cardiac pathophysiology by precisely controlling protein function, localization, and degradation. This study set out to investigate the role and molecular mechanism of a DUB, USP25 (ubiquitin-specific peptidase 25), in pathological cardiac hypertrophy.

METHODS

The role of USP25 in myocardial hypertrophy was evaluated in murine cardiomyocytes in response to Ang II (angiotensin II) and transverse aortic constriction stimulation and in hypertrophic myocardium tissues of heart failure patients. Liquid chromotography with mass spectrometry/mass spectrometry analysis combined with Co-IP was used to identify SERCA2a (sarcoplasmic/endoplasmic reticulum Ca2+-ATPase 2A), an antihypertrophy protein, as an interacting protein of USP25. To clarify the molecular mechanism of USP25 in the regulation of SERCA2a, we constructed a series of mutant plasmids of USP25. In addition, we overexpressed USP25 and SERCA2a in the heart with adenoassociated virus serotype 9 vectors to validate the biological function of USP25 and SERCA2a interaction.

RESULTS

We revealed increased protein level of USP25 in murine cardiomyocytes subject to Ang II and transverse aortic constriction stimulation and in hypertrophic myocardium tissues of patients with heart failure. USP25 deficiency aggravated cardiac hypertrophy and cardiac dysfunction under Ang II and transverse aortic constriction treatment. Mechanistically, USP25 bound to SERCA2a directly via its USP (ubiquitin-specific protease) domain and cysteine at position 178 of USP25 exerts deubiquitination to maintain the stability of the SERCA2a protein by removing the K48 ubiquitin chain and preventing proteasomal pathway degradation, thereby maintaining calcium handling in cardiomyocytes. Moreover, restoration of USP25 expression via adenoassociated virus serotype 9 vectors in USP25^-/- mice attenuated Ang II-induced cardiac hypertrophy and cardiac dysfunction, whereas myocardial overexpression of SERCA2a could mimic the effect of USP25.

CONCLUSIONS

We confirmed that USP25 inhibited cardiac hypertrophy by deubiquitinating and stabilizing SERCA2a.

USP20 is a predictor of poor prognosis in colorectal cancer and associated with lymph node metastasis, immune infiltration and chemotherapy resistance

Background

Colorectal cancer (CRC) is a highly prevalent malignancy with a poor prognosis. USP20 can support progression of variety of tumors. USP20 was shown to promote breast tumor metastasis, and proliferation of oral squamous carcinoma cells. However, the role of USP20 in CRC remains unclear.

Methods

We used bioinformatics to analyze the expression and prognosis of USP20 in pan-cancer and explore the relationship between USP20 expression and immune infiltration, immune checkpoints, and chemotherapy resistance in CRC. The differential expression and prognostic role of USP20 in CRC was validated by qRT-PCR and immunohistochemistry. Cox univariate and multivariate analyses were performed to assess risk factors for poor prognosis of CRC, and new prognostic prediction models were constructed and evaluated by decision curve analysis (ROC) and receiver operating characteristic (DCA). USP20 was overexpressed in CRC cell lines to explore the effect of USP20 on the functionalities of CRC cells. Enrichment analyses were used to explore the possible mechanism of USP20 in CRC.

Results

The expression of USP20 was lower in CRC tissues than adjacent normal tissues. Compared with low USP20 expression patients, CRC patients with high USP20 expression level had shorter OS. Correlation analysis showed that USP20 expression was associated with lymph node metastasis. Cox regression analysis revealed USP20 as an independent risk factor for poor prognosis in CRC patients. ROC and DCA analyses showed that the performance of the newly constructed prediction model was better than the traditional TNM model. Immune infiltration analysis shown that USP20 expression is closely associated with T cell infiltration in CRC. A co-expression analysis showed that USP20 expression was positively correlated with several immune checkpoint genes including ADORA2A, CD160, CD27 and TNFRSF25 genes and positively associated with multiple multi-drug resistance genes such as MRP1, MRP3, and MRP5 genes. USP20 expression positively correlated with the sensitivity of cells to multiple anticancer drugs. Overexpression of USP20 enhanced the migration and invasive ability of CRC cells. Enrichment pathway analyses showed the USP20 may play a role via the Notch pathway, Hedgehog pathway and beta-catenin pathway.

Conclusion

USP20 is downregulated in CRC and associated with prognosis in CRC. USP20 enhances CRC cells metastasis and is associated with immune infiltration, immune checkpoints, and chemotherapy resistance.

OTUD1 promotes pathological cardiac remodeling and heart failure by targeting STAT3 in cardiomyocytes

Rationale: Understanding the molecular mechanisms of deleterious cardiac remodeling is important for the development of treatments for heart failure. Recent studies have highlighted a role of deubiquitinating enzymes in cardiac pathophysiology. In the present study, we screened for alteration of deubiquitinating enzymes in experimental models of cardiac remodeling, which indicated a potential role of OTU Domain-Containing Protein 1 (OTUD1). Methods: Wide-type or OTUD1 knockout mice with chronic angiotensin II infusion and transverse aortic constriction (TAC) were utilized to develop cardiac remodeling and heart failure. We also overexpressed OTUD1 in mouse heart with AAV9 vector to validate the function of OTUD1. LC-MS/MS analysis combined with Co-IP was used to identify the interacting proteins and substrates of OTUD1. Results: We found that OTUD1 is elevated in mouse heart tissues following chronic angiotensin II administration. OTUD1 knockout mice were significantly protected against angiotensin II-induced cardiac dysfunction, hypertrophy, fibrosis and inflammatory response. Similar results were obtained in the TAC model. Mechanistically, OTUD1 bounds to the SH2 domain of STAT3 and causes deubiquitination of STAT3. Cysteine at position 320 of OTUD1 exerts K63 deubiquitination to promote STAT3 phosphorylation and nuclear translocation, thereby increasing STAT3 activity to induce inflammatory responses, fibrosis, and hypertrophy in cardiomyocytes. Finally, OTUD1 overexpression by AAV9 vector increases Ang II-induced cardiac remodeling in mice and OTUD1-regulated responses can be inhibited by blocking STAT3. Conclusion: Cardiomyocyte OTUD1 promotes pathological cardiac remodeling and dysfunction by deubiquitinating STAT3. These studies have highlighted a novel role of OTUD1 in hypertensive heart failure and identified STAT3 as a target of OTUD1 in mediating these actions.

Stabilization of IGF2BP1 by USP10 promotes breast cancer metastasis via CPT1A in an m6A-dependent manner

Metastasis leads to the vast majority of breast cancer mortality. Increasing evidence has shown that N6-methyladenosine (m6A) modification and its associated regulators play a pivotal role in breast cancer metastasis. Here, we showed that overexpression of the m6A reader IGF2BP1 was clinically correlated with metastasis in breast cancer patients. Moreover, IGF2BP1 promoted distant metastasis in vitro and in vivo. Mechanistically, we first identified USP10 as the IGF2BP1 deubiquitinase. USP10 can bind to, deubiquitinate, and stabilize IGF2BP1, resulting in its higher expression level in breast cancer. Furthermore, by MeRIP-seq and experimental verification, we found that IGF2BP1 directly recognized and bound to the m6A sites on CPT1A mRNA and enhanced its stability, which ultimately mediated IGF2BP1-induced breast cancer metastasis. In clinical samples, USP10 levels correlated with IGF2BP1 and CPT1A levels, and breast cancer patients with high levels of USP10, IGF2BP1, and CPT1A had the worst outcome. Therefore, these findings suggest that the USP10/IGF2BP1/CPT1A axis facilitates breast cancer metastasis, and this axis may be a promising prognostic biomarker and therapeutic target for breast cancer.

Noninvasive prediction of axillary lymph node status in breast cancer using promoter profiling of circulating cell-free DNA

BACKGROUND

Lymph node metastasis (LNM) is one of the most important factors affecting the prognosis of breast cancer. The accurate evaluation of lymph node status is useful to predict the outcomes of patients and guide the choice of cancer treatment. However, there is still lack of a low-cost non-invasive method to assess the status of axillary lymph node (ALN). Gene expression signature has been used to assess lymph node metastasis status of breast cancer. In addition, nucleosome footprint of cell-free DNA (cfDNA) carries gene expression information of its original tissues, so it may be used to evaluate the axillary lymph node status in breast cancer.

METHODS

In this study, we found that the cfDNA nucleosome footprints between the ALN-positive patients and ALN-negative patients showed different patterns by implementing whole-genome sequencing (WGS) to detect 15 ALN-positive and 15 ALN-negative patients. In order to further evaluate its potential for assessing ALN status, we developed a classifier with multiple machine learning models by using 330 WGS data of cfDNA from 162 ALN-positive and 168 ALN-negative samples to distinguish these two types of patients.

RESULTS

We found that the promoter profiling between the ALN-positive patients and ALN-negative patients showed distinct patterns. In addition, we observed 1071 genes with differential promoter coverage and their functions were closely related to tumorigenesis. We found that the predictive classifier based on promoter profiling with a support vector machine model, named PPCNM, produced the largest area under the curve of 0.897 (95% confidence interval 0.86-0.93).

CONCLUSIONS

These results indicate that promoter profiling can be used to distinguish ALN-positive patients from ALN-negative patients, which may be helpful to guide the choice of cancer treatment.

LncRNA ELF3-AS1 inhibits gastric cancer by forming a negative feedback loop with SNAI2 and regulates ELF3 mRNA stability via interacting with ILF2/ILF3 complex

BACKGROUND

The biological function of lncRNA ELF3-AS1 remains largely unknown in cancers. The cause of SNAI2 overexpression in tumor metastasis remains largely unclear. The molecular mechanisms underlying the high co-expression of antisense lncRNAs and adjacent protein-coding genes remains unclear.

METHODS

RNA-seq, CHIP and dual-luciferase reporter assay were performed to identify lncRNAs regulated by SNAI2. MicroRNA-seq and RNA-seq studies were conducted to reveal the biological function of ELF3-AS1 in GC. RNA pulldown and CHIRP assays were conducted to identify the protein that interacts with ELF3-AS1.

RESULTS

A total of 123 lncRNAs were identified to be regulated by SNAI2 in GC by RNA sequencing. The ELF3 gene and antisense lncRNA ELF3-AS1 were both transcriptionally repressed by SNAI2 or SNAI1. Down-regulation of ELF3-AS1 and ELF3 predicted poor prognosis in GC. Nuclear localized lncRNA ELF3-AS1 negatively regulated GC cell cycle progression via suppressing G1/S transition and histone synthesis. ELF3-AS1 mainly inhibited GC metastasis by repressing SNAI2 signaling. Additionally, ELF3-AS1 modulated ELF3 mRNA stability by RNA-RNA interaction. The RNA duplexes formed by ELF3 mRNA and lncRNA ELF3-AS1 directly interacted with the double-stranded RNA (dsRNA) binding protein complex ILF2/ILF3 (NF45/NF90). In turn, the ILF2/ILF3 complex dynamically regulated the expression of ELF3-AS1 and ELF3 by affecting the dsRNA stability.

CONCLUSIONS

The SNAI2-ELF3-AS1 feedback loop regulates ELF3 expression at transcriptional and post-transcriptional levels and drives gastric cancer metastasis by maintaining SNAI2 overexpression. The ILF2/ILF3 complex plays a critical role in regulating dsRNA stability. In addition, our work provides a direct evidence that head-to-head antisense lncRNAs can share promoters with neighboring coding genes, which make their expression subject to similar transcriptional regulation, leading to high co-expression.

The intricate interplay between HIFs, ROS, and the ubiquitin system in the tumor hypoxic microenvironment

Alterations in protein ubiquitination and hypoxia-inducible factor (HIF) signaling both contribute to tumorigenesis and tumor progression. Ubiquitination is a dynamic process that is coordinately regulated by E3 ligases and deubiquitinases (DUBs), which have emerged as attractive therapeutic targets. HIF expression and transcriptional activity are usually increased in tumors, leading to poor clinical outcomes. Reactive oxygen species (ROS) are upregulated in tumors and have multiple effects on HIF signaling and the ubiquitin system. A growing body of evidence has shown that multiple E3 ligases and UBDs function synergistically to control the expression and activity of HIF, thereby allowing cancer cells to cope with the hypoxic microenvironment. Conversely, several E3 ligases and DUBs are regulated by hypoxia and/or HIF signaling. Hypoxia also induces ROS production, which in turn modulates the stability or activity of HIF, E3 ligases, and DUBs. Understanding the complex networks between E3 ligase, DUBs, ROS, and HIF will provide insights into the fundamental mechanism of the cellular response to hypoxia and help identify novel molecular targets for cancer treatment. We review the current knowledge on the comprehensive relationship between E3 ligase, DUBs, ROS, and HIF signaling, with a particular focus on the use of E3 ligase or DUB inhibitors in cancer.

Emerging potential of ubiquitin-specific proteases and ubiquitin-specific proteases inhibitors in breast cancer treatment

Breast cancer is the most frequently diagnosed cancer in women, accounting for 30% of new diagnosing female cancers. Emerging evidence suggests that ubiquitin and ubiquitination played a role in a number of breast cancer etiology and progression processes. As the primary deubiquitinases in the family, ubiquitin-specific peptidases (USPs) are thought to represent potential therapeutic targets. The role of ubiquitin and ubiquitination in breast cancer, as well as the classification and involvement of USPs are discussed in this review, such as USP1, USP4, USP7, USP9X, USP14, USP18, USP20, USP22, USP25, USP37, and USP39. The reported USPs inhibitors investigated in breast cancer were also summarized, along with the signaling pathways involved in the investigation and its study phase. Despite no USP inhibitor has yet been approved for clinical use, the biological efficacy indicated their potential in breast cancer treatment. With the improvements in phenotypic discovery, we will know more about USPs and USPs inhibitors, developing more potent and selective clinical candidates for breast cancer.

The molecular mechanisms and therapeutic strategies of EMT in tumor progression and metastasis

Epithelial–mesenchymal transition (EMT) is an essential process in normal embryonic development and tissue regeneration. However, aberrant reactivation of EMT is associated with malignant properties of tumor cells during cancer progression and metastasis, including promoted migration and invasiveness, increased tumor stemness, and enhanced resistance to chemotherapy and immunotherapy. EMT is tightly regulated by a complex network which is orchestrated with several intrinsic and extrinsic factors, including multiple transcription factors, post-translational control, epigenetic modifications, and noncoding RNA-mediated regulation. In this review, we described the molecular mechanisms, signaling pathways, and the stages of tumorigenesis involved in the EMT process and discussed the dynamic non-binary process of EMT and its role in tumor metastasis. Finally, we summarized the challenges of chemotherapy and immunotherapy in EMT and proposed strategies for tumor therapy targeting EMT.

Deubiquitinases in Cancers: Aspects of Proliferation, Metastasis, and Apoptosis

Simple Summary

This review summarizes the current DUBs findings that correlate with the most common cancers in the world (liver, breast, prostate, colorectal, pancreatic, and lung cancers). The DUBs were further classified by their biological functions in terms of proliferation, metastasis, and apoptosis. The work provides an updated of the current findings, and could be used as a quick guide for researchers to identify target DUBs in cancers.

Abstract

Deubiquitinases (DUBs) deconjugate ubiquitin (UBQ) from ubiquitylated substrates to regulate its activity and stability. They are involved in several cellular functions. In addition to the general biological regulation of normal cells, studies have demonstrated their critical roles in various cancers. In this review, we evaluated and grouped the biological roles of DUBs, including proliferation, metastasis, and apoptosis, in the most common cancers in the world (liver, breast, prostate, colorectal, pancreatic, and lung cancers). The current findings in these cancers are summarized, and the relevant mechanisms and relationship between DUBs and cancers are discussed. In addition to highlighting the importance of DUBs in cancer biology, this study also provides updated information on the roles of DUBs in different types of cancers.

Copper ionophore elesclomol selectively targets GNAQ/11-mutant uveal melanoma

Unlike cutaneous melanoma, uveal melanoma (UM) is characterized by mutations in GNAQ and GNA11 and remains a fatal disease because there is essentially no effective targeted therapy or immunotherapy available. We report the discovery of the copper ionophore elesclomol as a GNAQ/11-specific UM inhibitor. Elesclomol was identified in a differential cytotoxicity screen of an in-house tool compound library, and its in vivo pharmacological efficacy was further confirmed in zebrafish and mouse UM models. Mechanistically, elesclomol transports copper to mitochondria and produces a large amount of reactive oxygen species (ROS) as Cu(II) is reduced to Cu(I) in GNAQ/11-mutant UM cells, which selectively activates LATS1 kinase in the Hippo signaling pathway and consequently promotes YAP phosphorylation and inhibits its nuclear accumulation. The inactivation of YAP downregulates the expression of SNAI2, which in turn suppresses the migration of UM cells. These findings were cross validated by our clinical observation that YAP activation was found specifically in UM samples with a GNAQ/11 mutation. Furthermore, addition of binimetinib, a MEK inhibitor, to elesclomol increased its synthetic lethality to GNAQ/11-mutant UM cells, thereby overriding drug resistance. This effect was confirmed in an orthotopic xenograft model and in a patient-derived xenograft model of UM. These studies reveal a novel mechanistic basis for repurposing elesclomol by showing that copper homeostasis is a GNAQ/11-specific vulnerability in UM. Elesclomol may provide a new therapeutic path for selectively targeting malignant GNAQ/11-mutant UM.

Research Progress of DUB Enzyme in Hepatocellular Carcinoma

According to GLOBOCAN 2021 cancer incidence and mortality statistics compiled by the International Agency for Research on Cancer, hepatocellular carcinoma (HCC) is the most common malignancy in the human liver and one of the leading causes of cancer death worldwide. Although there have been great advances in the treatment of HCC, such as regofenib, sorafenib, and lomvatinib, which have been developed and approved for the clinical treatment of advanced or metastatic HCC. However, they only prolong survival by a few months, and patients with advanced liver cancer are susceptible to tumor invasion metastasis and drug resistance. Ubiquitination modification is a type of post-translational modification of proteins. It can affect the physiological activity of cells by regulating the localization, stability and activity of proteins, such as: gene transcription, DNA damage signaling and other pathways. The reversible process of ubiquitination is called de-ubiquitination: it is the process of re-releasing ubiquitinated substrates with the participation of de-ubiquitinases (DUBs) and other active substances. There is growing evidence that many dysregulations of DUBs are associated with tumorigenesis. Although dysregulation of deuquitinase function is often found in HCC and other cancers, The mechanisms of action of many DUBs in HCC have not been elucidated. In this review, we focused on several deubiquitinases (DUBs) associated with hepatocellular carcinoma, including their structure, function, and relationship to hepatocellular carcinoma. hepatocellular carcinoma was highlighted, as well as the latest research reports. Among them, we focus on the USP family and OTU family which are more studied in the HCC. In addition, we discussed the prospects and significance of targeting DUBs as a new strategy for the treatment of hepatocellular carcinoma. It also briefly summarizes the research progress of some DUB-related small molecule inhibitors and their clinical application significance as a treatment for HCC in the future.

PIWI-interacting RNAs in human diseases: databases and computational models

PIWI-interacting RNAs (piRNAs) are short 21-35 nucleotide molecules that comprise the largest class of non-coding RNAs and found in a large diversity of species including yeast, worms, flies, plants and mammals including humans. The most well-understood function of piRNAs is to monitor and protect the genome from transposons particularly in germline cells. Recent data suggest that piRNAs may have additional functions in somatic cells although they are expressed there in far lower abundance. Compared with microRNAs (miRNAs), piRNAs have more limited bioinformatics resources available. This review collates 39 piRNA specific and non-specific databases and bioinformatics resources, describes and compares their utility and attributes and provides an overview of their place in the field. In addition, we review 33 computational models based upon function: piRNA prediction, transposon element and mRNA-related piRNA prediction, cluster prediction, signature detection, target prediction and disease association. Based on the collection of databases and computational models, we identify trends and potential gaps in tool development. We further analyze the breadth and depth of piRNA data available in public sources, their contribution to specific human diseases, particularly in cancer and neurodegenerative conditions, and highlight a few specific piRNAs that appear to be associated with these diseases. This briefing presents the most recent and comprehensive mapping of piRNA bioinformatics resources including databases, models and tools for disease associations to date. Such a mapping should facilitate and stimulate further research on piRNAs.

Epithelial–mesenchymal transition: The history, regulatory mechanism, and cancer therapeutic opportunities

Epithelial–mesenchymal transition (EMT) is a program wherein epithelial cells lose their junctions and polarity while acquiring mesenchymal properties and invasive ability. Originally defined as an embryogenesis event, EMT has been recognized as a crucial process in tumor progression. During EMT, cell–cell junctions and cell–matrix attachments are disrupted, and the cytoskeleton is remodeled to enhance mobility of cells. This transition of phenotype is largely driven by a group of key transcription factors, typically Snail, Twist, and ZEB, through epigenetic repression of epithelial markers, transcriptional activation of matrix metalloproteinases, and reorganization of cytoskeleton. Mechanistically, EMT is orchestrated by multiple pathways, especially those involved in embryogenesis such as TGFβ, Wnt, Hedgehog, and Hippo, suggesting EMT as an intrinsic link between embryonic development and cancer progression. In addition, redox signaling has also emerged as critical EMT modulator. EMT confers cancer cells with increased metastatic potential and drug resistant capacity, which accounts for tumor recurrence in most clinic cases. Thus, targeting EMT can be a therapeutic option providing a chance of cure for cancer patients. Here, we introduce a brief history of EMT and summarize recent advances in understanding EMT mechanisms, as well as highlighting the therapeutic opportunities by targeting EMT in cancer treatment.

The emerging role of ubiquitin-specific protease 20 in tumorigenesis and cancer therapeutics

As a critical member of the ubiquitin-specific proteolytic enzyme family, ubiquitin-specific peptidase 20 (USP20) regulates the stability of proteins via multiple signaling pathways. In addition, USP20 upregulation is associated with various cellular biological processes, such as cell cycle progression, proliferation, migration, and invasion. Emerging studies have revealed the pivotal role of USP20 in the tumorigenesis of various cancer types, such as breast cancer, colon cancer, lung cancer, gastric cancer and adult T cell leukemia. In our review, we highlight the different mechanisms of USP20 in various tumor types and demonstrate that USP20 regulates the stability of multiple proteins. Therefore, regulating the activity of USP20 is a novel tumor treatment. However, the clinical significance of USP20 in cancer treatment merits more evidence. Finally, different prospects exist for the continued research focus of USP20.

Ribonucleotide reductase holoenzyme inhibitor COH29 interacts with deubiquitinase ubiquitin-specific protease 2 and downregulates its substrate protein cyclin D1

USP2 contributes to the quality control of multiple oncogenic proteins including cyclin D1, Mdm2, Aurora-A, etc., and it is a potential target for anti-cancer drug development. However, currently only a few inhibitors with moderate inhibition activities against USP2 have been discovered. USP2-targeted active compounds with either new scaffolds or enhanced activities are in need. Here in this study, Ub-AMC hydrolysis assay-based screening against ~4000 commercially available drugs and drug candidates was performed to identify USP2-targeted inhibitors. COH29, which was originally developed as an anti-cancer agent by blocking the function of human ribonucleotide reductase (RNR, IC₅₀  = 16 µM), was found to exhibit an inhibition activity against USP2 with the IC₅₀ value at 2.02 ± 0.16 µM. The following conducted biophysical and biochemical experiments demonstrated that COH29 could specifically interact with USP2 and inhibit its enzymatic activity in a noncompetitive inhibition mode (K_i  = 1.73 ± 0.14 µM). Since COH29 shows similar inhibitory potencies against RNR (RRM2) and USP2, USP2 inhibition-dependent cellular consequences of COH29 are expected. The results of cellular assays confirmed that the application of COH29 could downregulate the level of cyclin D1 by enhancing its degradation via ubiquitin-proteasome system (UPS), and the modulation effect of COH29 on cyclin D1 is independent of RRM2. Since cyclin D1 acts as an oncogenic driver in human cancer, our findings suggest that USP2 might be a promising therapeutic target for cyclin D1-addicted cancers, and COH29 could serve as a starting compound for high selectivity inhibitor development against USP2.

USP20 regulates the stability of EMT transcription factor SOX4 and influences colorectal cancer metastasis

BACKGROUND

Colorectal cancer (CRC) is a familiar malignancy accompanied by higher morbidity and mortality. The deubiquitination enzyme USP20 has been discovered to be one key factor in several cancers progression. SOX4 is a critical transcription factor to regulate the expression of various genes, and participates into the occurrence and progression of cancers. In this study, it was aimed to illustrate the role of USP20 and the regulatory relationship between USP20 and SOX4 in CRC.

METHODS

The protein expressions of USP20, SOX4, E-cadherin, N-cadherin, Snail and slug were tested through western blot. The cell proliferation ability was verified through CCK-8 assay. The migration and invasion abilities were detected through Transwell assay. The mRNA expression of SOX4 was confirmed through RT-qPCR. The interaction between USP20 and SOX4 was notarized through Co-IP assay.

RESULT

Our study demonstrated that USP20 displayed higher expression, and facilitated CRC progression through regulating cell proliferation, migration, invasion and EMT process markers. USP20 was found to modulate SOX4 protein expression. Next, it was verified that USP20 regulated SOX4 degradation through deubiquitination. Finally, through rescue assays, we revealed that USP20 mediated SOX4 expression to accelerate CRC progression.

CONCLUSIONS

In this study, USP20 regulated the stability of EMT transcription factor SOX4 and aggravated colorectal cancer metastasis. This finding might highlight the function of USP20 in the treatment of CRC.

Sleeve gastrectomy improves lipid dysmetabolism by downregulating the USP20-HSPA2 axis in diet-induced obese mice

INTRODUCTION

Obesity is a metabolic disease accompanied by abnormalities in lipid metabolism that can cause hyperlipidemia, non-alcoholic fatty liver disease, and artery atherosclerosis. Sleeve gastrectomy (SG) is a type of bariatric surgery that can effectively treat obesity and improve lipid metabolism. However, its specific underlying mechanism remains elusive.

METHODS

We performed SG, and sham surgery on two groups of diet-induced obese mice. Histology and lipid analysis were used to evaluate operation effect. Immunohistochemistry, immunoblotting, real-time quantitative PCR, immunoprecipitation, immunofluorescence and mass spectrometry were used to reveal the potential mechanisms of SG.

RESULTS

Compared to the sham group, the SG group displayed a downregulation of deubiquitinase ubiquitin-specific peptidase 20 (USP20). Moreover, USP20 could promote lipid accumulation in vitro. Co-immunoprecipitation and mass spectrometry analyses showed that heat-shock protein family A member 2 (HSPA2) potentially acts as a substrate of USP20. HSPA2 was also downregulated in the SG group and could promote lipid accumulation in vitro. Further research showed that USP20 targeted and stabilized HSPA2 via the ubiquitin-proteasome pathway.

CONCLUSION

The downregulation of the USP20-HSPA2 axis in diet-induced obese mice following SG improved lipid dysmetabolism, indicating that USP20-HSPA2 axis was a noninvasive therapeutic target to be investigated in the future.

Roles and Mechanisms of Deubiquitinases (DUBs) in Breast Cancer Progression and Targeted Drug Discovery

Deubiquitinase (DUB) is an essential component in the ubiquitin—proteasome system (UPS) by removing ubiquitin chains from substrates, thus modulating the expression, activity, and localization of many proteins that contribute to tumor development and progression. DUBs have emerged as promising prognostic indicators and drug targets. DUBs have shown significant roles in regulating breast cancer growth, metastasis, resistance to current therapies, and several canonical oncogenic signaling pathways. In addition, specific DUB inhibitors have been identified and are expected to benefit breast cancer patients in the future. Here, we review current knowledge about the effects and molecular mechanisms of DUBs in breast cancer, providing novel insight into treatments of breast cancer-targeting DUBs.

JOSD1 promotes proliferation and chemoresistance of head and neck squamous cell carcinoma under the epigenetic regulation of BRD4

BACKGROUND

Deubiquitinating enzymes (DUBs) play critical roles in various cancers by modulating functional proteins post-translationally. Previous studies have demonstrated that DUB Josephin Domain Containing 1 (JOSD1) is implicated in tumor progression, however, the role and mechanism of JOSD1 in head and neck squamous cell carcinoma (HNSCC) remain to be explored. In this study, we aimed to identify the clinical significance and function of JOSD1 in HNSCC.

METHODS

The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were analyzed to find novel DUBs in HNSCC. Immunohistochemistry assay was performed to determine the expression of JOSD1 in our cohort of 42 patients suffered with HNSCC. Kaplan-Meier analysis was used to identify the correlation between JOSD1 and the prognosis of HNSCC patients. The regulation of BRD4 on JOSD1 was determined by using pharmacological inhibition and gene depletion. The in vitro and in vivo experiments were conducted to elucidate the role of JOSD1 in HNSCC.

RESULTS

The results of IHC showed that JOSD1 was aberrantly expressed in HNSCC specimens, especially in the chemoresistant ones. The overexpression of JOSD1 indicated poor clinical outcome of HNSCC patients. Moreover, JOSD1 depletion dramatically impaired cell proliferation and colony formation, and promoted cisplatin-induced apoptosis of HNSCC cells in vitro. Additionally, JOSD1 suppression inhibited the tumor growth and improved chemosensitivity in vivo. The epigenetic regulator BRD4 contributed to the upregulation of JOSD1 in HNSCC.

CONCLUSIONS

These results demonstrate that JOSD1 functions as an oncogene in HNSCC progression, and provide a promising target for clinical diagnosis and therapy of HNSCC.

PRL1 Promotes Glioblastoma Invasion and Tumorigenesis via Activating USP36-Mediated Snail2 Deubiquitination

Regenerating liver phosphatase 1 (PRL1) is an established oncogene in various cancers, although its biological function and the underlying mechanisms in glioblastoma multiforme (GBM) remain unclear. Here, we showed that PRL1 was significantly upregulated in glioma tissues and cell lines, and positively correlated with the tumor grade. Consistently, ectopic expression of PRL1 in glioma cell lines significantly enhanced their tumorigenicity and invasion both in vitro and in vivo by promoting epithelial-mesenchymal transition (EMT). Conversely, knocking down PRL1 blocked EMT in GBM cells, and inhibited their invasion, migration and tumorigenic growth. Additionally, PRL1 also stabilized Snail2 through its deubiquitination by activating USP36, thus revealing Snail2 as a crucial mediator of the oncogenic effects of PRL1 in GBM pathogenesis. Finally, PRL1 protein levels were positively correlated with that of Snail2 and predicted poor outcome of GBMs. Collectively, our data support that PRL1 promotes GBM progression by activating USP36-mediated Snail2 deubiquitination. This novel PRL1/USP36/Snail2 axis may be a promising therapeutic target for glioblastoma.

HES1 promotes breast cancer stem cells by elevating Slug in triple-negative breast cancer

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer. TNBC is enriched with breast cancer stem cells (BCSCs), which are responsible for cancer initiation, cancer progression and worse prognosis. Our previous study found that HES1 was overexpressed and promoted invasion in TNBC. However, the role of HES1 in modulating BCSC stemness of TNBC remains unclear. Here, we found that HES1 upregulates Slug both in transcriptional level and in protein level. HES1 also has a positive correlation with Slug expression in 150 TNBC patient samples. TNBC patients with high HES1 and Slug levels show worse prognosis in both progression-free survival and overall survival analyses. Survival analyses indicate that the effects of HES1 on survival prognosis may depend on Slug. Furthermore, we reveal that HES1 is a novel transcriptional activator for Slug through acting directly on its promoter. Meanwhile, HES1 knockdown reduces BCSC self-renewal, BCSC population, and cancer cell proliferation in TNBC, whereas overexpression of Slug restores the oncogenic function of HES1, both in vitro and in vivo, suggesting that HES1 performs its oncogenic role through upregulating Slug. Taken together, HES1 promotes BCSC stemness properties via targeting Slug, highlighting that HES1 might be a novel candidate for BCSC stemness regulation in TNBC and providing new clues for identifying promising prognostic biomarkers and therapeutic targets of TNBC.