USP26 promotes esophageal squamous cell carcinoma metastasis through stabilizing Snail

Acetylation-dependent deubiquitinase USP26 stabilizes BAG3 to promote breast cancer progression

Deubiquitylases (DUBs) have emerged as promising targets for cancer therapy due to their role in stabilizing substrate proteins within the ubiquitin machinery. Here, we identified ubiquitin-specific protease 26 (USP26) as an oncogene via screening prognostic DUBs in breast cancer. Through in vitro and in vivo experiments, we found that depletion of USP26 inhibited breast cancer cell proliferation and invasion, and suppressed tumor growth and metastasis in nude mice. Further investigation identified co-chaperone Bcl-2-associated athanogene 3 (BAG3) as the direct substrate of USP26, and ectopic expression of BAG3 partially reversed antitumor effect induced by USP26 knockdown. Mechanistically, the lysine acetyltransferase Tip60 targeted USP26 at K134 for acetylation, which enhanced USP26 binding affinity to BAG3, leading to BAG3 deubiquitination and increased protein stability. Importantly, we employed a structure-based virtual screening and discovered a drug-like molecule called 5813669 that targets USP26, destabilizing BAG3 and effectively mitigating tumor growth and metastasis in vivo. Clinically, high expression levels of USP26 were correlated with elevated BAG3 levels and poor prognosis in breast cancer patients. Overall, our findings highlight the critical role of USP26 in BAG3 protein stabilization and provide a promising therapeutic target for breast cancer.

USP26 promotes colorectal cancer tumorigenesis by restraining PRKN-mediated mitophagy

Deubiquitinating enzymes (DUBs) are promising targets for cancer therapy because of their pivotal roles in various physiological and pathological processes. Among these, ubiquitin-specific peptidase 26 (USP26) is a protease with crucial regulatory functions. Our study sheds light on the upregulation of USP26 in colorectal cancer (CRC), in which its increased expression correlates with an unfavorable prognosis. Herein, we evidenced the role of USP26 in promoting CRC tumorigenesis in a parkin RBR E3 ubiquitin-protein ligase (PRKN) protein-dependent manner. Our investigation revealed that USP26 directly interacted with PRKN protein, facilitating its deubiquitination, and subsequently reducing its activity. Additionally, we identified the K129 site on PRKN as a specific target for USP26-mediated deubiquitination. Our research highlights that a K-to-R mutation at the site on PRKN diminishes its potential for activation and ability to mediate mitophagy. In summary, our findings underscore the significance of USP26-mediated deubiquitination in restraining the activation of the PRKN-mediated mitophagy pathway, ultimately driving CRC tumorigenesis. This study not only elucidated the multifaceted role of USP26 in CRC but also introduced a promising avenue for therapeutic exploration through the development of small molecule inhibitors targeting USP26. This strategy holds promise as a novel therapeutic approach for CRC.

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.

Role of deubiquitinase JOSD2 in the pathogenesis of esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a deadly malignancy with limited treatment options. Deubiquitinases (DUBs) have been confirmed to play a crucial role in the development of malignant tumors. JOSD2 is a DUB involved in controlling protein deubiquitination and influencing critical cellular processes in cancer.

AIM

To investigate the impact of JOSD2 on the progression of ESCC.

METHODS

Bioinformatic analyses were employed to explore the expression, prognosis, and enriched pathways associated with JOSD2 in ESCC. Lentiviral transduction was utilized to manipulate JOSD2 expression in ESCC cell lines (KYSE30 and KYSE150). Functional assays, including cell proliferation, colony formation, drug sensitivity, migration, and invasion, were performed, revealing the impact of JOSD2 on ESCC cell lines. JOSD2's role in xenograft tumor growth and drug sensitivity in vivo was also assessed. The proteins that interacted with JOSD2 were identified using mass spectrometry.

RESULTS

Preliminary research indicated that JOSD2 was highly expressed in ESCC tissues, which was associated with poor prognosis. Further analysis demonstrated that JOSD2 was upregulated in ESCC cell lines compared to normal esophageal cells. JOSD2 knockdown inhibited ESCC cell activity, including proliferation and colony-forming ability. Moreover, JOSD2 knockdown decreased the drug resistance and migration of ESCC cells, while JOSD2 overexpression enhanced these phenotypes. In vivo xenograft assays further confirmed that JOSD2 promoted tumor proliferation and drug resistance in ESCC. Mechanistically, JOSD2 appears to activate the MAPK/ERK and PI3K/AKT signaling pathways. Mass spectrometry was used to identify crucial substrate proteins that interact with JOSD2, which identified the four primary proteins that bind to JOSD2, namely USP47, IGKV2D-29, HSP90AB1, and PRMT5.

CONCLUSION

JOSD2 plays a crucial role in enhancing the proliferation, migration, and drug resistance of ESCC, suggesting that JOSD2 is a potential therapeutic target in ESCC.

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.

Machine learning-based classification of deubiquitinase USP26 and its cell proliferation inhibition through stabilizing KLF6 in cervical cancer

OBJECTIVE

We aim to accurately distinguish ubiquitin-specific proteases (USPs) from other members within the deubiquitinating enzyme families based on protein sequences. Additionally, we seek to elucidate the specific regulatory mechanisms through which USP26 modulates Krüppel-like factor 6 (KLF6) and assess the subsequent effects of this regulation on both the proliferation and migration of cervical cancer cells.

METHODS

All the deubiquitinase (DUB) sequences were classified into USPs and non-USPs. Feature vectors, including 188D, n-gram, and 400D dimensions, were extracted from these sequences and subjected to binary classification via the Weka software. Next, thirty human USPs were also analyzed to identify conserved motifs and ascertained evolutionary relationships. Experimentally, more than 90 unique DUB-encoding plasmids were transfected into HeLa cell lines to assess alterations in KLF6 protein levels and to isolate a specific DUB involved in KLF6 regulation. Subsequent experiments utilized both wild-type (WT) USP26 overexpression and shRNA-mediated USP26 knockdown to examine changes in KLF6 protein levels. The half-life experiment was performed to assess the influence of USP26 on KLF6 protein stability. Immunoprecipitation was applied to confirm the USP26-KLF6 interaction, and ubiquitination assays to explore the role of USP26 in KLF6 deubiquitination. Additional cellular assays were conducted to evaluate the effects of USP26 on HeLa cell proliferation and migration.

RESULTS

1. Among the extracted feature vectors of 188D, 400D, and n-gram, all 12 classifiers demonstrated excellent performance. The RandomForest classifier demonstrated superior performance in this assessment. Phylogenetic analysis of 30 human USPs revealed the presence of nine unique motifs, comprising zinc finger and ubiquitin-specific protease domains. 2. Through a systematic screening of the deubiquitinase library, USP26 was identified as the sole DUB associated with KLF6. 3. USP26 positively regulated the protein level of KLF6, as evidenced by the decrease in KLF6 protein expression upon shUSP26 knockdown in both 293T and Hela cell lines. Additionally, half-life experiments demonstrated that USP26 prolonged the stability of KLF6. 4. Immunoprecipitation experiments revealed a strong interaction between USP26 and KLF6. Notably, the functional interaction domain was mapped to amino acids 285-913 of USP26, as opposed to the 1-295 region. 5. WT USP26 was found to attenuate the ubiquitination levels of KLF6. However, the mutant USP26 abrogated its deubiquitination activity. 6. Functional biological assays demonstrated that overexpression of USP26 inhibited both proliferation and migration of HeLa cells. Conversely, knockdown of USP26 was shown to promote these oncogenic properties.

CONCLUSIONS

1. At the protein sequence level, members of the USP family can be effectively differentiated from non-USP proteins. Furthermore, specific functional motifs have been identified within the sequences of human USPs. 2. The deubiquitinating enzyme USP26 has been shown to target KLF6 for deubiquitination, thereby modulating its stability. Importantly, USP26 plays a pivotal role in the modulation of proliferation and migration in cervical cancer cells.

Deubiquitinating enzyme OTUD4 regulates metastasis in triple-negative breast cancer by stabilizing Snail1

Metastasis is the primary cause of cancer-related deaths and remains poorly understood. Deubiquitinase OTU domain containing 4 (OTUD4) has been reported to regulate antiviral immune responses and resistance to radio- or chemo-therapies in certain cancers. However, the role of OTUD4 in cancer metastasis remain unknown. Here, we demonstrate that the depletion of OTUD4 in triple-negative breast cancer (TNBC) cells markedly suppress cell clonogenic ability, migration, invasion and cancer stem cell population in vitro as well as metastasis in vivo. Mechanistically, the tumor promoting function of OTUD4 is mainly mediated by deuiquitinating and stabilizing Snail1, one key transcriptional factor in the epithelial-mesenchymal transition. The inhibitory effect of targeting OTUD4 could be largely reversed by the reconstitution of Snail1 in OTUD4-deficient cells. Overall, our study establishes the OTUD4-Snail1 axis as an important regulatory mechanism of breast cancer metastasis and provides a rationale for potential therapeutic interventions in the treatment of TNBC.

ERK3 Increases Snail Protein Stability by Inhibiting FBXO11-Mediated Snail Ubiquitination

Snail is a key regulator of the epithelial-mesenchymal transition (EMT), the key step in the tumorigenesis and metastasis of tumors. Although induction of Snail transcription precedes the induction of EMT, the post-translational regulation of Snail is also important in determining Snail protein levels, stability, and its ability to induce EMT. Several kinases are known to enhance the stability of the Snail protein by preventing its ubiquitination; however, the precise molecular mechanisms by which these kinases prevent Snail ubiquitination remain unclear. Here, we identified ERK3 as a novel kinase that interacts with Snail and enhances its protein stability. Although ERK3 could not directly phosphorylate Snail, Erk3 increased Snail protein stability by inhibiting the binding of FBXO11, an E3 ubiquitin ligase that can induce Snail ubiquitination and degradation, to Snail. Importantly, functional studies and analysis of clinical samples indicated the crucial role of ERK3 in the regulation of Snail protein stability in pancreatic cancer. Therefore, we conclude that ERK3 is a key regulator for enhancing Snail protein stability in pancreatic cancer cells by inhibiting the interaction between Snail and FBXO11.

Androgen Receptor/AP-1 Activates UGT2B15 Transcription to Promote Esophageal Squamous Cell Carcinoma Invasion

Esophageal squamous cell carcinoma (ESCC) is an aggressive epithelial malignancy with poor prognosis. Interestingly, ESCC is strongly characterized by a male-predominant propensity. Our previous study showed that androgen receptor (AR) orchestrated a transcriptional repression program to promote ESCC growth, but it remains unclear whether AR can also activate oncogenic signaling during ESCC progression. In this study, by analyzing our previous AR cistromes and androgen-regulated transcriptomes, we identified uridine diphosphate glucuronosyltransferase family 2 member B15 (UGT2B15) as a bona fide target gene of AR. Mechanistically, AP-1 cofactors played important and collaborative roles in AR-mediated UGT2B15 upregulation. Functional studies have revealed that UGT2B15 promoted invasiveness in vitro and lymph node metastasis in vivo. UGT2B15 was partially responsible for the AR-induced invasive phenotype in ESCC cells. Importantly, simultaneous blocking of AP-1 and AR resulted in stronger inhibition of cell invasiveness compared to inhibiting AP-1 or AR alone. In conclusion, our study reveals the molecular mechanisms underlying the AR-driven ESCC invasion and suggests that the AR/AP1/UGT2B15 transcriptional axis can be potentially targeted in suppressing metastasis in male ESCC patients.

Deubiquitinase YOD1 suppresses tumor progression by stabilizing E3 ligase TRIM33 in head and neck squamous cell carcinoma

Ubiquitination is a reversible process that not only controls protein synthesis and degradation, but also is essential for protein transport, localization and biological activity. Deubiquitinating enzyme (DUB) dysfunction leads to various diseases, including cancer. In this study, we aimed to explore the functions and mechanisms of crucial DUBs in head and neck squamous cell carcinoma (HNSCC). Based on bioinformatic analysis and immunohistochemistry detection, YOD1 was identified to be significantly downregulated in HNSCC specimens compared with adjacent normal tissues. Further analysis revealed that reduced YOD1 expression was associated with the malignant progression of HNSCC and indicated poor prognosis. The results of the in vitro and in vivo experiments verified that YOD1 depletion significantly promoted growth, invasion, and epithelial-mesenchymal transition in HNSCC. Mechanistically, YOD1 inhibited the activation of the ERK/β-catenin pathway by suppressing the ubiquitination and degradation of TRIM33, leading to the constriction of HNSCC progression. Overall, our findings reveal the molecular mechanism underlying the role of YOD1 in tumor progression and provide a novel potential therapeutic target for HNSCC treatment.

USP41 Enhances Epithelial-Mesenchymal Transition of Breast Cancer Cells through Snail Stabilization

Ubiquitination, one of many post-translational modifications, causes proteasome-mediated protein degradation by attaching ubiquitin to target proteins. Multiple deubiquitinases inhibit the ubiquitination pathway by removing the ubiquitin chain from protein, thus contributing to the stabilization of substrates. USP41 contributes to invasion, apoptosis and drug resistance in breast and lung cancer cells. However, the detailed mechanism and role of USP41 in breast cancer have not been elucidated. USP41 was overexpressed and showed poor prognosis according to the aggressive phenotype of breast cancer cells. Knockdown of USP41 inhibited migration and growth of breast cancer cells, whereas overexpression of USP41 increased cell growth and migration. In addition, depletion of USP41 downregulated Snail protein expression, an epithelial-mesenchymal transition marker, but not mRNA expression. Furthermore, USP41 interacted with and inhibited ubiquitination of Snail, resulting in the increase in Snail stabilization. Therefore, these data demonstrated that USP41 increases migration of breast cancer cells through Snail stabilization.

Post-Translational Modification of ZEB Family Members in Cancer Progression

Post-translational modification (PTM), the essential regulatory mechanisms of proteins, play essential roles in physiological and pathological processes. In addition, PTM functions in tumour development and progression. Zinc finger E-box binding homeobox (ZEB) family homeodomain transcription factors, such as ZEB1 and ZEB2, play a pivotal role in tumour progression and metastasis by induction epithelial-mesenchymal transition (EMT), with activation of stem cell traits, immune evasion and epigenetic reprogramming. However, the relationship between ZEB family members' post-translational modification (PTM) and tumourigenesis remains largely unknown. Therefore, we focussed on the PTM of ZEBs and potential therapeutic approaches in cancer progression. This review provides an overview of the diverse functions of ZEBs in cancer and the mechanisms and therapeutic implications that target ZEB family members' PTMs.

PSMA1 mediates tumor progression and poor prognosis of gastric carcinoma by deubiquitinating and stabilizing TAZ

The deubiquitinating enzyme family in tumor progression play important role in intracellular protein degradation. The proteasome subunit alpha type 1 (PSMA1) has been reported to act as an oncogene in several human cancers. The present study aimed to reveal the functional significance of PSMA1 in gastric cancer (GC) progression and the underlying mechanisms. The expression of PSMA1 in human GC samples and GC cell lines was examined by western blot analysis, real-time PCR, immunohistochemistry (IHC), and in vitro ubiquitination assays and established a xenograft mouse model. We found that PSMA1 was upregulated in GC and promoted proliferation, migration and invasion in GC cells. Herein, we report transcriptional co-activator with PDZ-binding motif (TAZ) was a downstream gene of PSMA1. Mechanistically, PSMA1 directly interacted with and stabilized TAZ via deubiquitination in GC. Furthermore, we found that TAZ was the essential mediator of PSMA1-modulated oncogenic activity in vitro and in vivo. Examination of clinical samples confirmed that elevated mediators of PSMA1, concomitant with increased TAZ abundance, correlate with human GC progression. These data suggested that PSMA1 promotes GC progression and proliferation by deubiquitinating TAZ. PSMA1 promotes GC progression and proliferation regarding PSMA1-mediated deubiquitinating enzyme activity and suggest potential therapeutic targets for GC management.

HuR Affects the Radiosensitivity of Esophageal Cancer by Regulating the EMT-Related Protein Snail

Purpose

We previously found that Hu antigen R (HuR) can regulate the proliferation and metastasis of esophageal cancer cells. This study aims to explore the effects of HuR on the radiosensitivity of esophageal cancer.

Materials and Method

Analyses of CCK-8, colony formation assay, Western blot, immunofluorescence, flow cytometry, reactive oxygen species (ROS), and mitochondrial membrane potential were conducted to characterize the esophageal cancer cells. Nude mouse models were used to detect the effects of HuR in a combination of X-ray treatment on the subcutaneous xenografts of esophageal cancer. In addition, a luciferase assay was used to detect the direct interaction of HuR with Snail mRNA 3’-UTR.

Results

The down-regulation of HuR combined with X-ray can significantly inhibit the proliferation and colony formation of esophageal cancer cells. Flow cytometry data showed that the down-regulation of HuR could induce a G1 phase cell cycle block in esophageal cancer cells, and aggravate X-ray-induced apoptosis, indicated by the increases of apoptosis-related proteins Bax, caspase-3 and caspase-9. Moreover, the down-regulation of HuR could significantly impair the mitochondrial membrane potential and increase the ROS production and DNA double-strand break marker γH2AX expression in esophageal cancer cells that were exposed to X-rays. In vivo data showed that the down-regulation of HuR combined with radiation significantly decreased the growth of subcutaneous xenograft tumors. Furthermore, HuR could interact with Snail. Up-regulation of Snail can reverse the EMT inhibitory effects caused by HuR down-regulation, and attenuate the tumor-inhibiting and radiosensitizing effects caused by HuR down-regulation.

Conclusion

In summary, our data demonstrate that HuR effectively regulates the radiosensitivity of esophageal cancer, which may be achieved by stabilizing Snail. Thus, HuR/Snail axis is a potentially therapeutic target for the treatment of esophageal cancer.

USP26 promotes anaplastic thyroid cancer progression by stabilizing TAZ

Anaplastic thyroid cancer (ATC) is one of the most lethal and aggressive human malignancies, with no effective treatment currently available. The Hippo tumor suppressor pathway is highly conserved in mammals and plays an important role in carcinogenesis. TAZ is one of major key effectors of the Hippo pathway. However, the mechanism supporting abnormal TAZ expression in ATC remains to be characterized. In the present study, we identified USP26, a DUB enzyme in the ubiquitin-specific proteases family, as a bona fide deubiquitylase of TAZ in ATC. USP26 was shown to interact with, deubiquitylate, and stabilize TAZ in a deubiquitylation activity-dependent manner. USP26 depletion significantly decreased ATC cell proliferation, migration, and invasion. The effects induced by USP26 depletion could be rescued by further TAZ overexpression. Depletion of USP26 decreased the TAZ protein level and the expression of TAZ/TEAD target genes in ATC, including CTGF, ANKRD1, and CYR61. In general, our findings establish a previously undocumented catalytic role for USP26 as a deubiquitinating enzyme of TAZ and provides a possible target for the therapy of ATC.

MicroRNAs and Corresponding Targets in Esophageal Cancer as Shown In Vitro and In Vivo in Preclinical Models

Squamous cell carcinoma of the esophagus is associated with a dismal prognosis. Therefore, identification of new targets and implementation of new treatment modalities are issues of paramount importance. Based on a survey of the literature, we identified microRNAs conferring antitumoral activity in preclinical in vivo experiments. In the category of miRs targeting secreted factors and transmembrane receptors, four miRs were up-regulated and 10 were down-regulated compared with five out of nine in the category transcription factors, and six miRs were down-regulated in the category enzymes, including metabolic enzymes. The down-regulated miRs have targets which can be inhibited by small molecules or antibody-related entities, or re-expressed by reconstitution therapy. Up-regulated miRs have targets which can be reconstituted with small molecules or inhibited with antagomirs.

The osteoprotective role of USP26 in coordinating bone formation and resorption

Bone homeostasis is maintained through a balance of bone formation by osteoblasts and bone resorption by osteoclasts. Ubiquitin-specific proteases (USPs) are involved in regulating bone metabolism by preserving bone formation or antagonizing bone resorption. However, the specific USPs that maintain bone homeostasis by orchestrating bone formation and bone resorption simultaneously are poorly understood. Here, we identified USP26 as a previously unknown regulator of bone homeostasis that coordinates bone formation and resorption. Mechanistically, USP26 stabilizes β-catenin to promote the osteogenic activity of mesenchymal cells (MSCs) and impairs the osteoclastic differentiation of bone myelomonocytes (BMMs) by stabilizing inhibitors of NF-κBα (IκBα). Gain-of-function experiments revealed that Usp26 supplementation significantly increased bone regeneration in bone defects in aged mice and decreased bone loss resulting from ovariectomy. Taken together, these data show the osteoprotective effect of USP26 via the coordination of bone formation and resorption, suggesting that USP26 represents a potential therapeutic target for osteoporosis.

SNAIL1: Linking Tumor Metastasis to Immune Evasion

The transcription factor Snail1, a key inducer of epithelial-mesenchymal transition (EMT), plays a critical role in tumor metastasis. Its stability is strictly controlled by multiple intracellular signal transduction pathways and the ubiquitin-proteasome system (UPS). Increasing evidence indicates that methylation and acetylation of Snail1 also affects tumor metastasis. More importantly, Snail1 is involved in tumor immunosuppression by inducing chemokines and immunosuppressive cells into the tumor microenvironment (TME). In addition, some immune checkpoints potentiate Snail1 expression, such as programmed death ligand 1 (PD-L1) and T cell immunoglobulin 3 (TIM-3). This mini review highlights the pathways and molecules involved in maintenance of Snail1 level and the significance of Snail1 in tumor immune evasion. Due to the crucial role of EMT in tumor metastasis and tumor immunosuppression, comprehensive understanding of Snail1 function may contribute to the development of novel therapeutics for cancer.

Epigenetic Regulator KDM4D Restricts Tumorigenesis via Modulating SYVN1/HMGB1 Ubiquitination Axis in Esophageal Squamous Cell Carcinoma

Background

Increasing researches have been reported that epigenetic alterations play critical roles in ESCC development. However, the role of the histone demethylase KDM4D in ESCC tumorigenesis is poorly investigated. This study aims to discover the underlying mechanisms between KDM4D and ESCC progression.

Methods

CCK-8 assays, clone formation assay and soft-agar assays were performed to assess cell proliferation. Transwell assay was utilized to assess cell migration efficiency, while sphere formation assay was used to evaluate the cell self-renewal ability. Bioinformatic analysis was conducted to identify prognostic factors and predict the potential E3 ubiquitin ligases. In vitro ubiquitination assay was conducted to confirm the regulations between SYVN1 and HMGB1. The mRNA levels or protein levels of genes were detected by real-time PCR and western blot analysis. In vivo tumor xenograft models were used to determine whether the HMGB1 inhibition affected the malignant features of ESCC cells.

Result

Epigenome screening and low-throughput validations highlighted that KDM4D is a tumor suppressor in ESCC. KDM4D expressed lowly in tumors that predicts poor prognosis. KDM4D deficiency significantly enhanced tumor growth, migration and stemness. Mechanistically, KDM4D transcriptionally activates SYVN1 expressions via H3K9me3 demethylation at the promoter region, thereby triggering the ubiquitin-dependent degradation of HMGB1. Low KDM4D depended on accumulated HMGB1 to drive ESCC progression and aggressiveness. Targeting HMGB1 (Glycyrrhizin) could remarkably suppress ESCC tumor growth in vitro and in vivo, especially in KDM4D-deficient cells.

Conclusions

We systematically identified KDM4D/SYVN1/HMGB1 axis in ESCC progression, proving novel biomarkers and potential therapeutic targets.

Epigenetic Regulation and Post-Translational Modifications of SNAI1 in Cancer Metastasis

SNAI1, a zinc finger transcription factor, not only acts as the master regulator of epithelial-mesenchymal transition (EMT) but also functions as a driver of cancer progression, including cell invasion, survival, immune regulation, stem cell properties, and metabolic regulation. The regulation of SNAI1 occurs at the transcriptional, translational, and predominant post-translational levels including phosphorylation, acetylation, and ubiquitination. Here, we discuss the regulation and role of SNAI1 in cancer metastasis, with a particular emphasis on epigenetic regulation and post-translational modifications. Understanding how signaling networks integrate with SNAI1 in cancer progression will shed new light on the mechanism of tumor metastasis and help develop novel therapeutic strategies against cancer metastasis.

ZIP4 promotes non-small cell lung cancer metastasis by activating snail-N-cadherin signaling axis

Non-small cell lung cancer (NSCLC) is one of the most critical health problems worldwide, with high incidence and poor survival rate. A zinc importer ZIP4 has been implicated in the process of tumor growth and metastasis of many cancers. However, its exact role and the underlying mechanism in NSCLC remains to be elucidated. In the present study, we found that human ZIP4 was substantially overexpressed in NSCLC tissues and was correlated with poor overall survival (OS) and progression-free survival (PFS). Overexpression of ZIP4 promoted cell migration, invasion and metastasis both in vitro and in a mouse lung metastasis model. Silencing of ZIP4 attenuated migration, invasion and metastasis. Mechanistically, overexpression of ZIP4 increased the expression of Snail, Slug and N-cadherin while genetic inactivation of ZIP4 downregulated the expression of above-mentioned genes. Further analysis showed that transcriptional factor Snail which modulates N-cadherin was involved in the process of ZIP4-mediated NSCLC migration and invasion. We also demonstrated that ZIP4 positively correlates with the levels of Snail, Slug and N-cadherin in mice lung metastasis tumors. Together, these results suggest that ZIP4 acts as an important regulator of Snail-N-cadherin signaling axis in promoting NSCLC progression and may serve as a novel predictive marker and therapeutic target in NSCLC.

HERC1 Regulates Breast Cancer Cells Migration and Invasion

Simple Summary

Breast cancer has the highest incidence and mortality in women worldwide, and, despite formidable advances in its prevention, detection, and treatment, the development of metastasis foci still represents a significant reduction in patients’ survival and life quality. The Ubiquitin-Proteasome System plays a fundamental role in the maintenance of protein balance, and its dysregulation has been associated with malignant transformation and tumor cells invasive potential. The objective of our work was focused on the identification of ubiquitination-related genes that could represent putative molecular targets for the treatment of breast cancer dissemination. For that purpose, we performed a genetic study and identified and validated HERC1 (HECT and RLD Domain Containing E3 Ubiquitin Protein Ligase Family Member 1) as a regulator of migration and invasion. We confirmed that its depletion reduces tumorigenicity and the appearance of metastasis foci and determined that HERC1 protein expression inversely correlates with breast cancer patients’ overall survival. Altogether, we demonstrate that HERC1 might represent a novel therapeutic target in breast cancer.

Abstract

Tumor cell migration and invasion into adjacent tissues is one of the hallmarks of cancer and the first step towards secondary tumors formation, which represents the leading cause of cancer-related deaths. This process is considered an unmet clinical need in the treatment of this disease, particularly in breast cancers characterized by high aggressiveness and metastatic potential. To identify and characterize genes with novel functions as regulators of tumor cell migration and invasion, we performed a genetic loss-of-function screen using a shRNA library directed against the Ubiquitin Proteasome System (UPS) in a highly invasive breast cancer derived cell line. Among the candidates, we validated HERC1 as a gene regulating cell migration and invasion. Furthermore, using animal models, our results indicate that HERC1 silencing affects primary tumor growth and lung colonization. Finally, we conducted an in silico analysis using publicly available protein expression data and observed an inverse correlation between HERC1 expression levels and breast cancer patients’ overall survival. Altogether, our findings demonstrate that HERC1 might represent a novel therapeutic target for the development or improvement of breast cancer treatment.

HN1 promotes tumor growth and metastasis of anaplastic thyroid carcinoma by interacting with STMN1

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive malignancies frequently associated with extrathyroidal extension and metastasis through pathways that remain unclear. Analysis of the cancer genome atlas (TCGA) database and an independent cohort showed that the expression of hematological and neurological expressed 1 (HN1) was higher in thyroid cancers than in normal tissues, and negatively correlated with progression-free survival. RT-PCR and immunohistochemistry revealed higher HN1 expression in ATC compared to healthy tissues and papillary thyroid carcinoma (PTC). HN1 knockdown attenuated migration and invasion of ATC cells, whereas HN1 overexpression increased migration and invasion of PTC cells. HN1 reduced the acetylation of α-tubulin and promoted progression through epithelial-mesenchymal transition of ATC cells and mouse xenografts. HN1 knockdown significantly attenuated TGF-β-induced mesenchymal phenotype, and inhibited tumor formation and growth of ATC xenografts in nude mice. Loss of STMN1 decreased the malignant potential of HN1, whereas HN1 knockdown in combination with STMN1 overexpression restored the aggressive properties of ATC cells. HN1 increased STMN1 mRNA expression, and prevented STMN1 ubiquitination and subsequent degradation. These results demonstrate that HN1 interacts with STMN1 and drives ATC aggressiveness.

USP29 enhances chemotherapy-induced stemness in non-small cell lung cancer via stabilizing Snail1 in response to oxidative stress

Chemotherapy remains an essential part of diverse treatment regimens against human malignancies. However, recent progressions have revealed a paradoxical role of chemotherapies to induce the cancer stem cell-like features that facilitate chemoresistance and tumor dissemination, with the underlying mechanisms underinvestigated. The zinc-finger transcription factor Snail1 is a central regulator during the epithelial-mesenchymal transition process and is closely implicated in cancer progression. Snail1 expression is strictly regulated at multiple layers, with its stability governed by post-translational ubiquitylation that is counterbalanced by the activities of diverse E3 ligases and deubiquitylases. Here we identify the deubiquitylase USP29 as a novel stabilizer of Snail1, which potently restricts its ubiquitylation in a catalytic activity-dependent manner. Bioinformatic analysis reveals a reverse correlation between USP29 expression and prognosis in lung adenocarcinoma patients. USP29 is unique among Snail1 deubiquitylases through exhibiting chemotherapy-induced upregulation. Mechanistically, oxidative stresses incurred by chemotherapy stimulate transcriptional activation of USP29. USP29 upregulation enhances the cancer stem cell-like characteristics in lung adenocarcinoma cells to promote tumorigenesis in athymic nude mice. Our findings uncover a novel mechanism by which chemotherapy induces cancer stemness and suggest USP29 as a potential therapeutic target to impede the development of chemoresistance and metastasis in lung adenocarcinoma.

Biological role of epithelial-mesenchymal-transition-inducing transcription factors in head and neck squamous cell carcinoma: A systematic review

OBJECTIVE

The aim of this systematic review was to explore the biological functions and mechanisms of epithelial-mesenchymal transition-inducing transcription factors in head and neck squamous cell carcinoma-derived cell lines. In addition, we analyzed the possible usefulness of epithelial-mesenchymal transition-inducing transcription factors as a future therapeutic target.

DESIGN

An electronic search was performed in EMBASE, Medline/PubMed, Chinese BioMedical Literature Databases, and Cochrane Collaboration Library. Articles evaluating the relationship between epithelial-mesenchymal transition-inducing transcription factors and the biological behavior of head and neck squamous cell carcinoma cell lines were selected for this systematic review. The quality of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria.

RESULTS

After application of the previously established inclusion/exclusion criteria, 23 articles were included in the qualitative synthesis. Our study showed that epithelial-mesenchymal transition-inducing transcription factors are essential components during the progression of head and neck squamous cell carcinomas and their overexpression is associated with a greater capacity of dissemination and survival of the tumor and resistance to cancer treatment. The inhibition of epithelial-mesenchymal transition-inducing transcription factors is able to reverse the epithelial-mesenchymal transition process and to increase the sensitivity of head and neck squamous cell carcinoma cell lines to radio/chemotherapy.

CONCLUSIONS

Analysis of the expression of epithelial-mesenchymal transition-inducing transcription factors for the prediction of prognosis and response to cancer treatment may have a significant clinical impact.

EIF3H promotes aggressiveness of esophageal squamous cell carcinoma by modulating Snail stability

Background

Overexpression of eukaryotic translation initiation factor 3H (EIF3H) predicts cancer progression and poor prognosis, but the mechanism underlying EIF3H as an oncogene remains unclear in esophageal squamous cell carcinoma (ESCC).

Methods

TCGA database and the immunohistochemistry (IHC) staining of ESCC samples were used and determined the upregulation of EIF3H in ESCC. CCK8 assay, colony formation assay and transwell assay were performed to examine the ability of cell proliferation and mobility in KYSE150 and KYSE510 cell lines with EIF3H overexpression or knockdown. Xenograft and tail-vein lung metastatic mouse models of KYSE150 cells with or without EIF3H knockdown were also used to confirm the function of EIF3H on tumor growth and metastasis in vivo. A potential substrate of EIF3H was screened by co-immunoprecipitation assay (co-IP) combined with mass spectrometry in HEK293T cells. Their interaction and co-localization were confirmed using reciprocal co-IP and immunofluorescence staining assay. The function of EIF3H on Snail ubiquitination and stability was demonstrated by the cycloheximide (CHX) pulse-chase assay and ubiquitination assay. The correlation of EIF3H and Snail in clinical ESCC samples was verified by IHC.

Results

We found that EIF3H is significantly upregulated in esophageal cancer and ectopic expression of EIF3H in ESCC cell lines promotes cell proliferation, colony formation, migration and invasion. Conversely, genetic inhibition of EIF3H represses ESCC tumor growth and metastasis in vitro and in vivo. Moreover, we identified EIF3H as a novel deubiquitinating enzyme of Snail. We demonstrated that EIF3H interacts with and stabilizes Snail through deubiquitination. Therefore, EIF3H could promote Snail-mediated EMT process in ESCC. In clinical ESCC samples, there is also a positive correlation between EIF3H and Snail expression.

Conclusions

Our study reveals a critical EIF3H-Snail signaling axis in tumor aggressiveness in ESCC and provides EIF3H as a promising biomarker for ESCC treatment.

SREBP1 silencing inhibits the proliferation and motility of human esophageal squamous carcinoma cells via the Wnt/β-catenin signaling pathway

Sterol regulatory element-binding protein 1 (SREBP1) is dysregulated in a variety of types of human cancer. However, the functional roles of SREBP1 in esophageal squamous cell carcinoma (ESCC) remain poorly understood. The present study investigated the function of SREBP1 in cell proliferation and motility. Microarray datasets in Oncomine, reverse transcription-quantitative PCR and western blot analysis revealed that SREBP1 was overexpressed in ESCC tumors when compared with normal tissues. In addition, SREBP1 overexpression was significantly associated with tumor differentiation, lymphatic metastasis and Ki67 expression. Results suggested that silencing SREBP1 inhibited the proliferation, migration and invasion of ESCC cells, whereas overexpression of SREBP1 had opposite effects on proliferation and metastasis. In addition, loss of SREBP1 significantly increased E-cadherin and decreased N-cadherin, Vimentin, Snail, matrix metalloproteinase 9 and vascular endothelial growth factor C expression levels, which were restored via SREBP1-overexpression. Mechanistically, loss of SREBP1 suppressed T-cell factor 1/lymphoid enhancer factor 1 (TCF1/LEF1) activity and downregulated TCF1/LEF1 target proteins, including CD44 and cyclin D1. Moreover, knockdown of SREBP1 downregulated the expression levels of stearoyl-CoA desaturase 1 (SCD1), phosphorylated glycogen synthase kinase-3β and nuclear β-catenin. Furthermore, the inhibitors of SREBP1 and/or SCD1 and small interfering RNA-SCD1 efficiently inhibited the activation of the Wnt/β-catenin pathway driven by constitutively active SREBP1. Finally, in vivo results indicated that SREBP1-knockdown suppressed the proliferation and metastasis of ESCC. Taken together, these findings demonstrated that SREBP1 exerts oncogenic effects in ESCC by promoting proliferation and inducing epithelial-mesenchymal transition via the SCD1-induced activation of the Wnt/β-catenin signaling pathway.

Targeting deubiquitinating enzyme USP26 by microRNA-203 regulates Snail1's pro-metastatic functions in esophageal cancer

Background

Esophageal cancer is one of the most common cancers worldwide with poor prognosis and high mortality. The transcription factor SNAI1, encoding Snail1, is important for metastatic progression in esophageal cancer whereas the microRNA (miRNA)-203 has been shown to function as an inhibitor of metastasis in EC. The Snail1 protein is stabilized in EC partially by the deubiquitinating enzyme USP26; however, how USP26 is regulated is not completely known.

Methods

Expression of SNAI1 and USP26 messenger RNA (mRNA) and miR-203 was performed in datasets within The Cancer Genome Atlas and Gene Expression Omnibus, respectively. Expression of Snail1 and USP26 protein and miR-203 was determined in the normal esophageal cell line HET-1A and EC cell lines Kyse150 and TE-1 using western blot and quantitative polymerase chain reaction, respectively. TargetScan was used for in situ prediction of miR-203 targets and in vitro heterologous reporter assays using the wild-type and miR-203 seed mutant of the 3′ Untranslated region (UTR) of USP26 were used to investigate whether USP26 is a target of miR-203. Effects of increasing miR-203 using MIR203A/5P mimic on USP26 and Snail1 in the HET-1A, Kyse150 and TE-1 cell lines were performed using western blot and cycloheximide-based protein stability analysis. Effects of modulating miR-203 in Kyse150 and TE-1 cell lines on in vitro pro-metastatic effects were analyzed by invasion assay, scratch wound-healing assay, and chemosensitivity to 5-fluoruracil (5-FU). In vivo lung metastasis assay was used to study the effect of modulating miR-203 in Kyse150 cells.

Results

SNAI1 mRNA and HSA/MIR203 was higher and lower, respectively, in EC patients compared to tumor-adjacent normal tissues. No changes in expression of USP26 mRNA were observed in these datasets. MIR/203 expression was downregulated whereas protein expression of both Snail1 and USP26 were higher in EC cell lines Kyse150 and TE-1 compared to normal esophageal cell line HET-1A. USP26 was predicted as a potential target of miR-203 by TargetScan Release 2.0. Reporter assays confirmed USP26 as a target of miR-203 in the EC cell lines. Transfection of EC cell lines with MIR203 mimic decreased USP26 protein expression and Snail1 protein stability indicating the ability of miR-203 to regulate Snail1 protein levels via USP26. Exogenous increase in miR-203 in the EC cell lines significantly inhibited Snail-1 mediated in vitro pro-metastatic function of invasion, wound-healing, and increased chemosensitivity to 5-FU. Finally, overexpression of miR-203 inhibited in vivo lung metastasis of Kyse150 cells, which was reversed following overexpression of USP26, indicating a direct role of miR-203-mediated regulation of USP26 in metastatic progression of EC.

Conclusions

Cumulatively, these results establish an important mechanism by which decrease in miR-203 expression potentiates metastatic progression in EC via USP26-mediated stabilization of Snail1. Hence, miR-203 can serve as a biomarker of metastasis in EC and is a potential target for therapeutic intervention in EC.

Ubiquitin-specific peptidase 46 promotes tumor metastasis through stabilizing ENO1 in human esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) has high aggressiveness and poor prognosis, and is the major histological subtype of esophageal cancer in East Asia and East Africa. In this study, we found that USP46, a deubiquitinating enzyme, is overexpressed in clinical ESCC samples, especially in patients with positive lymph node metastasis. Moreover, USP46 enhances the migration and invasion of ESCC cells by mediating the EMT process in vitro, and promotes lymph nodes and lung metastasis of ESCC in vivo. In addition, we found that USP46 is a bona fide deubiquitinating enzyme to stabilize the protein level of ENO1 through deubiquitination. ENO1 protein level was also positively correlated with USP46 in the ESCC samples. In summary, these findings reveal the functional role of USP46 as a deubiquitinating enzyme on ESCC metastasis, providing us a potential therapeutic target for the treatment of ESCC.

The Deubiquitinase USP4 Stabilizes Twist1 Protein to Promote Lung Cancer Cell Stemness

Lung cancer stem cells (CSCs) play a pivotal role in tumor development, drug resistance, metastasis and recurrence of lung cancer. Thus, it is of great importance to study the mechanism by which CSCs are regulated. In this study, we demonstrate that the deubiquitinase USP4 is critically important in promoting lung cancer stemness. Silencing of USP4 leads to reduction of Oct4 and Sox2 expression, decreased CD133+ cell population and inhibition of tumorsphere formation. Conversely, ectopic expression of USP4 significantly enhances lung cancer cell stemness, which is effectively rescued by simultaneous silencing of Twist1. Mechanistically, we identified USP4 as a novel deubiquitinase of Twist1. USP4 binds to, deubiquitinates and stabilizes Twist1 protein. Furthermore, we show that USP4 expression is elevated in human lung cancer specimens and is positively correlated with Twist1 expression. High expression of USP4/Twist1 is associated with poor clinical outcomes of lung cancer patients. Together, this study highlights an important role for USP4 in lung cancer stemness and suggests USP4 as a potential target for lung cancer diagnosis and treatment.

CDK4/6 inhibition blocks cancer metastasis through a USP51-ZEB1-dependent deubiquitination mechanism

Tumor metastasis is the most common cause of cancer-related deaths, yet it remains poorly understood. The transcription factor zinc-finger E-box binding homeobox 1 (ZEB1) is involved in the epithelial-to-mesenchymal transition (EMT) and plays a pivotal role in tumor metastasis. However, the underlying mechanisms of the posttranslational modification of ZEB1 remain largely unknown. Herein, we demonstrated that specific inhibition of CDK4/6 was able to block tumor metastasis of breast cancer by destabilizing the ZEB1 protein in vitro and in vivo. Mechanistically, we determined that the deubiquitinase USP51 is a bona fide target of CDK4/6. The phosphorylation and activation of USP51 by CDK4/6 is necessary to deubiquitinate and stabilize ZEB1. Moreover, we found a strong positive correlation between the expression of p-RB (an indicator of CDK4/6 activity), p-USP51 and ZEB1 in metastatic human breast cancer samples. Notably, the high expression of p-RB, p-USP51, and ZEB1 was significantly correlated with a poor clinical outcome. Taken together, our results provide evidence that the CDK4/6-USP51-ZEB1 axis plays a key role in breast cancer metastasis and could be a viable therapeutic target for the treatment of advanced human cancers.

SERPINE2 promotes esophageal squamous cell carcinoma metastasis by activating BMP4

Metastasis is a major lethal cause of esophageal squamous cell carcinoma (ESCC) and confers a poor prognosis. Previous studies demonstrated that serpin family E member 2 (SERPINE2) is involved in tumor metastasis. However, the function and mechanism of SERPINE2 in ESCC metastasis remains unclear. In this study, we found that SERPINE2 was increased in ESCC and associated with tumor metastasis. SERPINE2 knockdown inhibited tumor cell invasion and lymph node and lung metastasis by inducing epithelial-mesenchymal transition (EMT). We identified a total of 410 differentially expressed genes in SERPINE2-knockdown cells by RNA-Seq analysis. Among them, bone morphogenetic protein 4 (BMP4) was significantly downregulated. Conversely, BMP4 was increased in SERPINE2-overexpressing cells. Inhibiting BMP4 could attenuate SERPINE2-induced migration and invasion. Moreover, SERPINE2 was positively correlated with clinical stage, tumor invasion depth and lymph node metastasis in ESCC patients. These findings suggest that SERPINE2 promotes tumor metastasis by activating BMP4 and could serve as a potential therapeutic target for clinical intervention in ESCC.

The role of DUBs in the post-translational control of cell migration

Cell migration is a multifactorial/multistep process that requires the concerted action of growth and transcriptional factors, motor proteins, extracellular matrix remodeling and proteases. In this review, we focus on the role of transcription factors modulating Epithelial-to-Mesenchymal Transition (EMT-TFs), a fundamental process supporting both physiological and pathological cell migration. These EMT-TFs (Snail1/2, Twist1/2 and Zeb1/2) are labile proteins which should be stabilized to initiate EMT and provide full migratory and invasive properties. We present here a family of enzymes, the deubiquitinases (DUBs) which have a crucial role in counteracting polyubiquitination and proteasomal degradation of EMT-TFs after their induction by TGFβ, inflammatory cytokines and hypoxia. We also describe the DUBs promoting the stabilization of Smads, TGFβ receptors and other key proteins involved in transduction pathways controlling EMT.

Identification of a multidimensional transcriptome prognostic signature for lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD) is one of the leading contributors to cancer-related deaths worldwide. The objective of the current study is to identify a multidimensional transcriptome prognostic signature by combining protein-coding gene (PCG) with long non-coding RNA (lncRNA) for patients with LUAD.

METHODS

We obtained LUAD PCG and lncRNA expression profile data from three datasets in the Gene Expression Omnibus database and conducted survival analyzes for these individuals.

RESULTS

We established a predictive model comprising the three PCGs (NHLRC2, PLIN5, GNAI3), and one lncRNA (AC087521.1). This model segregated patients with LUAD into low- and high-risk groups based on significant differences in survival in the training dataset (GSE31210, n = 226, log-rank test P < .001). Risk stratification of the model was subsequently validated in other two test datasets (GSE37745, n = 106, log-rank test P < .001; GSE30219, n = 85, log-rank test P = .006). Time-dependent receiver operating characteristic (timeROC) curve analysis demonstrated that the model correlated strongly with disease progression and outperformed pathological stage in terms of prognostic ability. Cox proportional hazards regression analysis revealed that the signature could serve as an independent predictor of clinical outcomes in patients with LUAD.

CONCLUSIONS

We describe a novel multidimensional transcriptome signature that can predict survival probabilities in patients with LUAD.

Snail1: A Transcriptional Factor Controlled at Multiple Levels

Snail1 transcriptional factor plays a key role in the control of epithelial to mesenchymal transition and fibroblast activation. As a consequence, Snail1 expression and function is regulated at multiple levels from gene transcription to protein modifications, affecting its interaction with specific cofactors. In this review, we describe the different elements that control Snail1 expression and its activity both as transcriptional repressor or activator.