Deubiquitination of MYC by OTUB1 contributes to HK2 mediated glycolysis and breast tumorigenesis

OTUB1 promotes the progression of acute myeloid leukemia by regulating glycolysis via deubiquitinating c-Myc

Acute myeloid leukemia (AML) is the most common type of adult leukemia and patients with AML often have poor prognosis, for which there remains an urgent need to identify novel selective targeted therapy. OTUB1, a deubiquitinating enzyme, is associated with the malignant progression of multiple cancers. However, the role of OTUB1 in AML is still unclear and warrants further investigations. Our study revealed that the expression of OTUB1 is significantly upregulated in AML. Next, we observed that knockdown of OTUB1 inhibits AML cell proliferation and promotes AML cell apoptosis and G0/G1 phase blockade using CCK-8 assay, western blotting, and flow cytometry. Mechanistically, OTUB1 drives the malignant development of AML through regulating cellular aerobic glycolysis by deubiquitinating c-Myc. Lastly, by investigating whether inhibition of OTUB1 enhances the sensitivity of chemotherapeutic agents commonly used in the clinical treatment of AML, we found that combining OTUB1 inhibition with daunorubicin treatment could achieve better therapeutic effects in AML. In brief, our results revealed a novel mechanism by which OTUB1 promotes glycolysis via deubiquitinating c-Myc in AML. Consequently, targeting OTUB1 may provide a promising strategy for enhancing the efficacy of AML treatment.

OTUB1 promotes glioma progression by stabilizing TRAF4

BACKGROUND

Glioma is a highly heterogeneous brain tumor with poor prognosis. This study aims to investigate the functional role of OTUB1 in glioma and its impact on TRAF4 stability, seeking potential therapeutic targets.

METHODS

We mined single-cell sequencing data from 12 glioma patients to analyze the heterogeneity of 20,145 glioma cells. The expression of OTUB1 in glioma tissues and cell lines was assessed using Western blot and qPCR. Additionally, immunoprecipitation and ubiquitination assays were conducted to evaluate the effect of OTUB1 on TRAF4 and its role in regulating TRAF4 stability. In vitro assays were performed to assess the effects of OTUB1 on cell proliferation, migration, and clonogenicity, while in vivo experiments using xenograft models in nude mice validated the impact of OTUB1 on tumor growth.

RESULTS

OTUB1 was found to be significantly overexpressed in glioma tissues, correlating with poor patient outcomes. Knockdown of OTUB1 markedly inhibited the proliferation and migration of LN229 and U87MG cells while increasing apoptosis. Immunoprecipitation studies revealed that OTUB1 stabilizes TRAF4 by inhibiting its ubiquitination, thereby promoting glioma cell proliferation and invasion. In vivo, tumors with OTUB1 knockdown demonstrated significantly reduced growth rates.

CONCLUSION

OTUB1 plays a critical role in glioma progression and may serve as a novel therapeutic target. The development of inhibitors targeting OTUB1 could potentially improve outcomes for glioma patients.

The synergy of TPL and selinexor in MLL-R acute myeloid leukemia via Rap1/Raf/MEK pathway-mediated MYC downregulation

MLL gene rearrangement recurrently occurs in acute myeloid leukemia (MLL-r AML), which is closely associated with chemotherapy insensitivity and unfavorable clinical outcomes. More importantly, there are limited therapeutic options for the management of patients with MLL-r AML, thus necessitating novel effective treatment strategies. In this study, we demonstrated that low doses of triptolide (LD TPL) and the XPO1 inhibitor selinexor exerted synergistic therapeutic effects on poor-outcome MLL-r AML in vitro, ex vivo and in vivo. Induction of mitochondrial outer membrane permeabilization (MOMP) and initiation of the mitochondrial apoptotic pathway were closely involved in the therapeutic synergy of LD TPL in combination with selinexor against MLL-r AML. Mechanistically, MYC downregulation mediated by the Rap1/Raf/MEK/ERK pathway rather than by PI3K/AKT signaling was implicated in the synergistic activity of the combined regimen. In addition, the induction of DNA damage also contributed to the synergistic effects of the combined regimen on MLL-r AML. In summary, our findings suggest that LD TPL in combination with selinexor might represent a promising therapeutic approach for the treatment of MLL-r AML. However, future clinical trials are mandatory to draw a decisive conclusion.

USP3 promotes clear cell renal cell carcinoma progression by stabilizing MYC and enhancing glycolysis

Clear cell renal cell carcinoma (ccRCC) is the most prevalent type of renal malignancy, and the deubiquitinase USP3 has been implicated as a critical factor in tumor biology. However, the precise mechanisms by which USP3 contributes to ccRCC progression remain unclear. This study investigates the role of USP3 in ccRCC and elucidates its underlying molecular mechanisms. Data from TCGA and GTEx databases showed elevated USP3 expression in ccRCC tissues and cell lines compared to normal renal tissues. Further analysis using qPCR and Western blot confirmed this upregulation in ccRCC cell lines. Functional assays revealed that silencing USP3 significantly impaired cell proliferation, migration, and invasion, while promoting apoptosis. Additionally, co-immunoprecipitation assays demonstrated an interaction between USP3 and MYC, with subsequent ubiquitination assays showing that USP3 regulates MYC stability. USP3 depletion also led to alterations in glycolysis-related gene expression, which could be partially reversed by MYC overexpression. These findings suggest that USP3 modulates ccRCC progression by stabilizing MYC, highlighting its potential as a therapeutic target in ccRCC treatment.

PYK2 promotes cell proliferation and epithelial-mesenchymal transition in endometriosis by phosphorylating Snail1

BACKGROUND

Endometriosis can lead to decreased endometrial receptivity, reduced rates of implantation, and diminished ovarian reserve. Currently, more than 50% of infertile women are found to suffer from endometriosis. However the etiology and pathogenesis of endometriosis are still poorly understood. Epithelial-mesenchymal transition (EMT) has been confirmed to be involved in endometriosis. PYK2 is a non-receptor tyrosine kinase that affects cell proliferation, survival, and migration by regulating intracellular signaling pathways. PYK2 plays a regulatory role in the EMT process by affecting the expression of genes associated with EMT through the influence of transcription factors. Snail1 (Snail1) plays a key role in the EMT process and is highly expressed in endometriosis tissues. On the other hand, Snail1 affects the invasive and metastatic ability of endometriosis cells mainly by regulating the EMT process. However, the upstream mechanisms that regulate the process of Snail1 protein stability in endometriosis are not clear.

METHODS

We identified a non-receptor tyrosine kinase, proline-rich tyrosine kinase 2 (PYK2 or PTK2B), and examined the expression of PYK2 in endometriosis. The relevant plasmids were constructed. This study enrolled 20 patients with laparoscopically confirmed endometriosis meeting ASRM diagnostic criteria, collecting ectopic lesions (14 ovarian endometriotic cysts and 6 deep infiltrating nodules) along with matched eutopic endometrial tissues (15 proliferative phase, 5 secretory phase) as controls. All tissue specimens underwent immunohistochemical analysis. Human endometrial stromal cells (HESC) were isolated from normal endometrium of 3 control patients for in vitro meconium induction. Ectopic endometrial stromal cells (EESC) were obtained from 5 ectopic lesions. Protein extracts from both ectopic tissues and cells were subjected to Western blot and co-immunoprecipitation (Co-IP) interaction validation. Functional assays (proliferation/migration/invasion) were performed using EESC and 11Z cell lines with triplicate biological replicates. Co-IP experiments were performed to verify the interaction between PYK2 and Snail1, as well as to determine the specific location of this interaction. Additionally, we examined the effect of PYK2 on endometriosis cells in vitro and whether VS-6063 inhibits the biological functions of endometriosis cells. Endometriosis models were established in 20 five-week-old female C57BL/6 mice, randomly allocated into experimental (n = 10) and control (n = 10) groups. Statistical analyses were conducted using GraphPad Prism 7.0, employing parametric tests for normally distributed data and non-parametric methods otherwise, with Benjamini-Hochberg correction for multiple comparisons.

RESULTS

PYK2 is highly expressed in endometriosis tissues. It acts as a new binding partner of Snail1 and enhances EMT in endometriosis by increasing the phosphorylation of Snail1. Additionally, PYK2 promotes the proliferation, migration, and invasion of endometriosis cells while inhibiting decidualization. We demonstrated that VS-6063 inhibited the proliferation, migration, and invasion of endometriosis cells in vitro, as well as the growth of endometriotic lesions in vivo.

CONCLUSIONS

PYK2 is a novel binding partner of Snail1. PYK2 promotes the occurrence and development of endometriosis by up-regulating Snail1, which could be a promising therapeutic target for endometriosis.

Mechanical Load-Induced Upregulation of Talin2 through Non-Canonical Deubiquitination of OTUB1 Drives Facet Joint Osteoarthritis Pathogenesis

Facet joint osteoarthritis (FJOA) is a prevalent degenerative condition in the aging population; however, the underlying pathophysiological mechanisms remain poorly understood and current therapeutic strategies remain limited to palliative pain management. In this study, novel potential therapeutic targets and prevention paradigms for FJOA are systematically explored. Proteomic screening and validation show that Talin2 is specifically upregulated in FJOA samples. Immunoprecipitation-mass spectrometry, transcriptome RNA sequencing, and bioinformatics simulation analyses, combined with in vitro and in vivo experiments, are conducted to elucidate the molecular mechanism of the role of Talin2 in FJOA. Increased expression levels of Talin2 in FJOA promote the degradation of the extracellular matrix and inhibit its synthesis. Talin2 is found to be stabilized via non-canonical deubiquitination and direct interaction with ovarian tumor domain-containing ubiquitin aldehyde-binding protein 1 (OTUB1). C-C motif ligand 2 (CCL2), an inflammatory chemoattractant, is identified to be a target gene of Talin2. Furthermore, mechanical loading potentiates the Talin2/OTUB1 interaction, resulting in the stabilization of Talin2 and enhances non-canonical deubiquitination. Therefore, Talin2 regulates CCL2 expression and promotes FJOA. Given that Talin2 is stabilized and deubiquitinated by OTUB1, especially under mechanical load, the Talin2/OTUB1 interaction may be a promising therapeutic target for FJOA.

TTC36 promotes proliferation and drug resistance in hepatocellular carcinoma cells by inhibiting c-Myc degradation

High c-Myc protein accumulation contributes to the proliferation, invasion, and drug resistance in multiple cancer cells, but the underlying mechanism about c-Myc accumulation remains not to be elucidated. Here, we demonstrate that TTC36 promotes c-Myc protein accumulation in hepatocellular carcinoma cells, thereby driving the proliferation and sorafenib resistance in hepatocellular carcinoma cells. Ttc36 depletion disrupts the interaction between SET and PPP2R1A, consequently activating PP2A. Activated PP2A directly dephosphorylates p-c-MycS62 and activates GSK3β, relying on AKT, leading increased phosphorylation of p-c-MycT58, finally promotes FBXW7-mediated polyubiquitination and degradation of c-Myc. Inhibitors targeting GSK3β and PP2A effectively reverse the sorafenib resistance promoted by TTC36. These findings highlight the crucial role of TTC36 in c-Myc accumulation-caused proliferation and sorafenib resistance in HCC, providing a promising combination strategy for treating patients with c-Myc protein accumulation in advanced HCC.

OTUB1 enhances fatty acid oxidation in APAP-induced liver injury by mediating ACSL5 deubiquitination

Overdosing on acetaminophen (APAP) is the primary cause of drug-induced liver injury. Recent studies have demonstrated that dysregulated lipid metabolism, particularly decreased fatty acid oxidation (FAO), is a key contributor to APAP-induced acute liver injury (AILI). OTU domain-containing ubiquitin aldehyde-binding protein 1 (OTUB1), a crucial member of the OTU deubiquitinase family, has been involved in the metabolic progression of multiple diseases. Nevertheless, its involvement in AILI as well as FAO remains unclear. Here, we aimed to elucidate the effects of OTUB1 on the regulation of FAO in AILI. Our investigation revealed decreased OTUB1 expression in AILI. OTUB1 overexpression not only alleviated liver injury but also improved FAO in vivo and in vitro. Conversely, opposite biochemical changes were observed in hepatocytes with OTUB1 knockdown. Mechanistically, long-chain acyl-CoA synthase 5 (ACSL5), which plays a crucial role in regulating FAO, was identified as a novel substrate of OTUB1 in AILI via mass spectrometry analysis. OTUB1 interacts with ACSL5 and promotes its deubiquitination and stability. Moreover, the protective effect of OTUB1 on FAO in AILI occurred via the deubiquitination of ACSL5. Overall, the present study revealed that the OTUB1-ACSL5 axis plays an essential role in regulating FAO during AILI progression and might be a novel target for therapeutic intervention.

Foot-and-mouth disease virus activates glycolysis and hijacks HK2 to inhibit innate immunity and promote viral replication

Foot-and-mouth disease (FMD) severely restricts the healthy development of global animal husbandry, and the unclear pathogenic mechanism of FMD virus (FMDV) leads to difficulty in preventing and purifying FMD. Glycolytic remodelling is considered one of the hallmarks of viral infection, providing energy and precursors for viral assembly and replication. In this work, the interaction and mechanism between FMDV and glycolysis were explored from the perspective of immune metabolism. We found that FMDV infection increased the extracellular acidification rate, lactic acid accumulation, and HK2 level. In addition, during FMDV infection, HK2 enhances glycolytic activity and mediates autophagic degradation of IRF3/7 to antagonize the innate immune response, thereby promoting viral replication. Our findings provide evidence that FMDV is closely correlated with host metabolism, increasing the understanding that glycolysis and HK2 facilitate virus infection, and provide new ideas for further elucidating the pathogenic mechanism of FMDV.

LT-α Facilitates the Aerobic Glycolysis and M1 Polarization of Macrophages by Activating the NF-κB Signaling Pathway in Intervertebral Disc Degeneration

Purpose

Injury and inflammatory activate and polarize macrophages in intervertebral disc degeneration (IVDD). Further research needs to be carried to explore the mechanisms that regulate macrophage polarization, providing new insights and targets for IVDD treatment. The aim of our study was to evaluate the influence of LT-α on aerobic glycolysis (AG) and polarization in macrophages.

Methods

M0 macrophages were achieved by stimulating THP-1 cells with PMA. M1 macrophages were obtained by IFN-γ and LPS stimulation in M0 macrophages. Energy metabolomics, AG and apoptosis related protein expression, migration and invasion measurement, proliferation was analyzed. Polarization of macrophages, AG associated genes expression, macrophage recruitment was evaluated. NF-κB signaling was ascertained by laser confocal and Western blotting.

Results

The propanoate metabolism pathway was enriched in LT-α overexpressing M0 macrophages, and various energy metabolites were detected. Glucose absorption, lactic acid production, and levels of AG proteins were strikingly increased in LT-α overexpression macrophages and remarkably repressed in LT-α knockdown macrophages, accompanied by activated and inactivated NF-κB signaling, respectively. Suppressed migration and invasion ability, restrained proliferation, activated AG, and enhanced apoptosis were observed in nucleus pulposus (NP) cells treated by LT-α overexpressed macrophages, accompanied by reduced macrophage recruitment, with opposite results when treated by LT-α knockdown macrophages. The enhanced M1 polarization and activated AG in LT-α overexpression macrophages were abolished by co-culturing with NF-κB inhibitor.

Conclusion

LT-α facilitates the AG and M1 polarization of macrophages via activating the NF-κB signaling pathway.

Sialylated IgG-activated integrin β4-Src-Erk axis stabilizes c-Myc in a p300 lysine acetyltransferase-dependent manner to promote colorectal cancer liver metastasis

BACKGROUND

Liver metastasis is a leading cause of colorectal cancer mortality. Therefore, the underlying mechanism and potential therapeutic target of colorectal cancer liver metastasis urge to be found. Mounting evidence indicates that cancer-derived sialylated IgG promotes tumor formation and progression. However, the role of sialylated IgG in colorectal cancer liver metastasis remains undefined.

MATERIALS AND METHODS

Analysis of sialylated IgG in paired tumor tissues and adjacent normal tissues from 65 colorectal cancer patients was performed using immunohistochemical staining. Functional assays of sialylated IgG were explored in vitro and in vivo. The downstream target of sialylated IgG was investigated by performing gene-set enrichment analysis, ubiquitination assay, cycloheximide chase assay, acetylation assay and co-immunoprecipitation.

RESULTS

Here, our investigation reveals that sialylated IgG is significantly upregulated in colorectal cancer and that the increase of IgG is positively associated with liver metastasis and poor overall survival in colorectal cancer patients. Sialylated IgG promotes colorectal cancer cell migration, invasion and liver metastasis. Notably, anti-sialylated IgG antibody effectively blocks colorectal cancer liver metastasis in mouse models. Mechanistically, sialylated IgG upregulates c-Myc protein level by decreasing c-Myc ubiquitination. Moreover, we find that p300/CBP can stabilize c-Myc by reducing c-Myc ubiquitination. Overexpression of p300/CBP protects c-Myc protein level from sialylated IgG-knockdown in a lysine acetyltransferase activity-dependent manner. Furthermore, sialylated IgG upregulates p300 protein level through integrin β4-FAK-Src-Erk signaling.

CONCLUSION

Collectively, these results indicate that a novel sialylated IgG-integrin β4-FAK-Src-Erk-p300-c-Myc signaling pathway promotes colorectal cancer liver metastasis, thus providing potential therapeutic targets for colorectal cancer liver metastasis.

Ailanthone induces triple-negative breast cancer cells death involving the inhibition of OTUB1-mediated ERRα deubiquitylation

INTRODUCTION

Triple-negative breast cancer (TNBC) remains the most aggressive subtype of breast cancer, and effective therapeutic strategies are needed. Estrogen-related receptor alpha (ERRα) is considered a promising target for managing TNBC.

OBJECTIVES

Here, we aimed to screen natural products to find downregulator of ERRα and elucidate its mechanism of action.

METHODS

TNBC cells (MDA-MB-231, MDA-MB-468, MDA-MB-453, and BT-549) were used for in vitro studies, and a subcutaneous MDA-MB-231 tumor model was created for in vivo studies. Immunofluorescence assessed protein distribution, while competitive activity-based protein profiling identified potential target proteins. Co-immunoprecipitation detected protein interactions and modifications, and a luciferase reporter assay evaluated ERRα transcriptional activity.

RESULTS

The natural product Ailanthone (AIL) effectively induced cell death in TNBC cells by reducing the protein level of ERRα. The mechanism of action involved AIL promoting the degradation of ERRα through the ubiquitin-proteasome system, consequently reducing its transcriptional activity. The competitive-ABPP method mapped the profile of target proteins for AIL, and OTU domain-containing ubiquitin aldehyde-binding protein 1 (OTUB1) was identified as a pivotal target of AIL in regulating ERRα protein levels. OTUB1 was validated as a novel deubiquitinating enzyme for ERRα, with its C91 residue being crucial for this deubiquitination process. AIL was found to inhibit the enzyme activity of OTUB1 by interacting with the C91 residue and disrupt the interaction between OTUB1 and ERRα, ultimately leading to the inhibition of ERRα.

CONCLUSION

AIL is a promising downregulator of ERRα, and the mechanism of this downregulation has been elucidated. Additionally, a new regulatory relationship between ERRα and OTUB1 is identified. The research presented in this article is anticipated to yield potential lead compounds for ERRα regulatory agents and to stimulate the development of novel therapeutic strategies designed to modulate ERRα activity for the treatment of TNBC.

DLGAP5 enhances bladder cancer chemoresistance by regulating glycolysis through MYC stabilization

Rationale: Bladder cancer (BLCA), one of the most lethal urological tumors, exhibits high rates of recurrence and chemoresistance, particularly to gemcitabine (GEM). Understanding the mechanisms of GEM resistance is crucial for improving therapeutic outcomes. Our study investigates the role of DLGAP5 in promoting GEM resistance through modulation of glycolysis and MYC protein stability in BLCA cells. Methods: We utilized various BLCA cell lines and clinical tissue samples to analyze the impact of DLGAP5 on GEM resistance. Through biochemical assays, protein interaction studies, and gene expression analyses, we examined how DLGAP5 interacts with USP11 and MYC, assessed the effects on MYC deubiquitination and stability. The influence of these interactions on glycolytic activity and GEM resistance was also evaluated via mouse subcutaneous xenograft model and spontaneous BLCA model. Results: Our findings indicate that DLGAP5 enhances GEM resistance by stabilizing MYC protein via deubiquitination, a process mediated by USP11. DLGAP5 was found to facilitate the interaction between USP11 and MYC, promoting MYC-driven transcription of DLGAP5 itself, thereby creating a positive feedback loop. This loop leads to sustained MYC accumulation and increased glycolytic activity, contributing to GEM resistance in BLCA cells. Conclusion: The study highlights the critical role of DLGAP5 in regulating MYC protein stability and suggests that disrupting the DLGAP5-USP11-MYC axis may provide a novel therapeutic approach to overcome GEM resistance in BLCA. DLGAP5 represents a potential target for therapeutic intervention aimed at mitigating chemoresistance in bladder cancer BLCA.

A peptide encoded by LINC00944 suppresses the growth of melanoma cells by diminishing EP400-MYC interaction

The peptides encoded by long noncoding RNAs (lncRNAs) have been shown to participate in cancer pathogenesis. In this study, lncRNA LINC00944 was validated to encode an endogenous 102-amino acid (aa) small peptide (named LINC00944 peptide). Functionally, LINC00944 peptide exerted an anti-growth effect in melanoma cells in vitro. Mechanistically, LINC00944 peptide interacted with the E1A binding protein p400 (EP400)/c-MYC complex. LINC00944 peptide also inhibited c-MYC protein expression. Furthermore, LINC00944 peptide repressed the transcriptional activity of MYC by reducing the EP400-MYC interaction, thereby reducing the levels of fatty acid metabolism- and glucose metabolism-related proteins. Our findings uncovered that LINC00944 peptide might be a promising adjuvant therapeutic agent for melanoma. Implications: This study provided the first evidence that LINC00944-encoded peptide played a critical role in the growth of melanoma cells.

Exploring the impact of deubiquitination on melanoma prognosis through single-cell RNA sequencing

Background

Cutaneous melanoma, characterized by the malignant proliferation of melanocytes, exhibits high invasiveness and metastatic potential. Thus, identifying novel prognostic biomarkers and therapeutic targets is essential.

Methods

We utilized single-cell RNA sequencing data (GSE215120) from the Gene Expression Omnibus (GEO) database, preprocessing it with the Seurat package. Dimensionality reduction and clustering were executed through Principal Component Analysis (PCA) and Uniform Manifold Approximation and Projection (UMAP). Cell types were annotated based on known marker genes, and the AUCell algorithm assessed the enrichment of deubiquitination-related genes. Cells were categorized into DUB_high and DUB_low groups based on AUCell scores, followed by differential expression analysis. Importantly, we constructed a robust prognostic model utilizing various genes, which was evaluated in the TCGA cohort and an external validation cohort.

Results

Our prognostic model, developed using Random Survival Forest (RSF) and Ridge Regression methods, demonstrated excellent predictive performance, evidenced by high C-index and AUC values across multiple cohorts. Furthermore, analyses of immune cell infiltration and tumor microenvironment scores revealed significant differences in immune cell distribution and microenvironment characteristics between high-risk and low-risk groups. Functional experiments indicated that TBC1D16 significantly impacts the migration and proliferation of melanoma cells.

Conclusion

This study highlights the critical role of deubiquitination in melanoma and presents a novel prognostic model that effectively stratifies patient risk. The model's strong predictive ability enhances clinical decision-making and provides a framework for future studies on the therapeutic potential of deubiquitination mechanisms in melanoma progression. Further validation and exploration of this model's applicability in clinical settings are warranted.

PAK5-mediated PKM2 phosphorylation is critical for anaerobic glycolysis in endometriosis

P21-activated kinase 5 (PAK5) belongs to the PAK-II subfamily, which is an important regulator of cell survival, adhesion, and motility. However, the functions of PAK5 in endometriosis remain unclear. Here, PAK5 is strikingly upregulated in endometriosis. Furthermore, the knockdown of PAK5 or its inhibitor GNE 2861 blocks the development of endometriosis, which is equally demonstrated in PAK5-knockout mice. In addition, PAK5 promotes glycolysis by enhancing the protein stability of pyruvate kinase 2 (PKM2) in endometriotic cells, which is a key enzyme for glucose metabolism. Moreover, the phosphorylation of PKM2 at Ser519 by PAK5 mediates endometriosis cell proliferation and metastasis. Collectively, PAK5 plays an indispensable role in endometriosis. Our findings demonstrate that PAK5 is an important target for the treatment of endometriosis.

Deubiquitinases as novel therapeutic targets for diseases

Deubiquitinating enzymes (DUBs) regulate substrate ubiquitination by removing ubiquitin or cleaving within ubiquitin chains, thereby maintaining cellular homeostasis. Approximately 100 DUBs in humans counteract E3 ubiquitin ligases, finely balancing ubiquitination and deubiquitination processes to maintain cellular proteostasis and respond to various stimuli and stresses. Given their role in modulating ubiquitination levels of various substrates, DUBs are increasingly linked to human health and disease. Here, we review the DUB family, highlighting their distinctive structural characteristics and chain-type specificities. We show that DUB family members regulate key signaling pathways, such as NF-κB, PI3K/Akt/mTOR, and MAPK, and play crucial roles in tumorigenesis and other diseases (neurodegenerative disorders, cardiovascular diseases, inflammatory disorders, and developmental diseases), making them promising therapeutic targets Our review also discusses the challenges in developing DUB inhibitors and underscores the critical role of the DUBs in cellular signaling and cancer. This comprehensive analysis enhances our understanding of the complex biological functions of the DUBs and underscores their therapeutic potential.

The deubiquitinase OTUB1 inhibits gluconeogenesis by stabilizing YWHAB

Hepatic gluconeogenesis plays a crucial role in maintaining glucose homeostasis and serves as a potential therapeutic target for type 2 diabetes, while its underlying mechanisms are not fully understood. This study elucidates the role of the deubiquitinase OTU domain-containing ubiquitin aldehyde binding protein 1 (OTUB1) in gluconeogenesis. We found that hepatic OTUB1 expression is reduced in both db/db mice and patients with type 2 diabetes. Deletion of hepatic OTUB1 significantly elevates fasting blood glucose levels and increases the expression of key gluconeogenic genes. Conversely, overexpression of OTUB1 in hepatocytes mitigates diabetic hyperglycemia and enhances insulin sensitivity. It is known that the tyrosine 3-monooxygenase/tryptophan 5-monooxygenase activation protein β (YWHAB) functions as an inhibitor of hepatic gluconeogenesis by interacting with forkhead box protein O (FOXO1) and glucagon receptor (GPCR), but its own modification mechanism remains unclear. Our findings indicate that OTUB1 interacts with YWHAB and deubiquitinates it through a catalytic process, which in turn suppresses gluconeogenesis. Therefore, OTUB1 plays a pivotal role in inhibiting hepatic gluconeogenesis, highlighting its potential as a therapeutic target for type 2 diabetes.

Mitochondrial bioenergetics of breast cancer

Breast cancer cells exhibit metabolic heterogeneity based on tumour aggressiveness. Glycolysis and mitochondrial respiration are two major metabolic pathways for ATP production. The oxygen flux, oxygen tension, proton leakage, protonmotive force, inner mitochondrial membrane potential, ECAR and electrochemical proton gradient maintain metabolic homeostasis, ATP production, ROS generation, heat dissipation, and carbon flow and are referred to as "sub-domains" of mitochondrial bioenergetics. Tumour aggressiveness is influenced by these mechanisms, especially when breast cancer cells undergo metastasis. These physiological parameters for healthy mitochondria are as crucial as energy demands for tumour growth and metastasis. The instant energy demands are already elucidated under Warburg effects, while these parameters may have dual functionality to maintain cellular bioenergetics and cellular health. The tumour cell might maintain these mitochondrial parameters for mitochondrial health or avoid apoptosis, while energy production could be a second priority. This review focuses explicitly on the crosstalk between metabolic domains and the utilisation of these parameters by breast cancer cells for their progression. Some major interventions are discussed based on mitochondrial bioenergetics that need further investigation. This review highlights the pathophysiological significance of mitochondrial bioenergetics and the regulation of its sub-domains by breast tumour cells for uncontrolled proliferation.

USP18 promotes the proliferation, invasion, and migration of head and neck squamous cell carcinoma by deubiquitinating PLK1

The ubiquitin specific peptidase 18 (USP18), a well-established deubiquitinase, has been extensively implicated in the malignant progression of various human tumors. However, its role in head and neck squamous cell carcinoma (HNSC) requires further investigation. Here, we revealed that USP18 was significantly upregulated in HNSC and knockdown of USP18 markedly suppressed tumor growth in vivo. Furthermore, silencing USP18 attenuated HNSC cell proliferation, invasion, and migration, while overexpression of USP18 exerted converse effects. Mechanistically, USP18 diminished K48-linked ubiquitination of polo-like kinase 1 (PLK1) to stabilize the protein through its deubiquitinase activity. Subsequently, we validated that USP18 modulated PLK1 to activate the mTORC1 pathway, thereby facilitating HNSC cell proliferation, invasion, and migration. In conclusion, our findings demonstrate that elevated expression of USP18 in HNSC cells promotes tumorigenesis by regulating the PLK1-mTORC1 pathway.

Research progress of the Otubains subfamily in hepatocellular carcinoma

In cancer research, oncogenesis can be affected by modulating the deubiquitination pathway. Ubiquitination regulates proteins post-translationally in variety of physiological processes. The Otubain Subfamily includes OTUB1 (ovarian tumor-associated proteinase B1) and OTUB2(ovarian tumor-associated proteinase B2). They are deubiquitinating enzymes, which are research hotspots in tumor immunotherapy, with their implications extending across the spectrum of tumor development. Understanding their important role in tumorigenesis, includ-ing hepatocellular carcinoma (HCC) is crucial. HCC has alarming global incidence rates and mortality statistics, ranking among the top five prevalent cancers in Malaysia1. Numerous studies have consistently indicated significant expression of OTUB1 and OTUB2 in HCC cells. In addition, OTUB1 has important biological functions in cancer, suggesting its important role in tumorigenesis. However, the mechanism underlying the action of OTUB1 and OTUB2 in liver cancer remains inadequately explored. Therefore, Otubain Subfamily, as potential molecular target, holds promise for advancing HCC treatments. However, further clinical studies are required to verify its efficacy and application prospects.

METTL3-mediated m6A modification of OTUD1 aggravates press overload induced myocardial hypertrophy by deubiquitinating PGAM5

Background: Pathological cardiac hypertrophy, a condition that contributes to heart failure, is characterized by its intricate pathogenesis. The meticulous regulation of protein function, localization, and degradation is a crucial role played by deubiquitinating enzymes in cardiac pathophysiology. This study clarifies the participation and molecular mechanism of OTUD1 (OTU Deubiquitinase 1) in pathological cardiac hypertrophy. Methods: We generated a cardiac-specific Otud1 knockout mouse line (Otud1-CKO) and adeno-associated virus serotype 9-Otud1 mice to determine the role of Otud1 in cardiac hypertrophy. Its impact on cardiomyocytes enlargement was investigated using the adenovirus. RNA immunoprecipitation was used to validate the specific m6a methyltransferase interacted with OTUD1 transcript. RNA sequencing in conjunction with immunoprecipitation-mass spectrometry analysis was employed to identify the direct targets of OTUD1. A series of depletion mutant plasmids were constructed to detect the interaction domain of OTUD1 and its targets. Results: Ang II-stimulated neonatal rat cardiac myocytes and mice hearts subjected to transverse aortic constriction (TAC) showed increased protein levels of Otud1. Cardiac hypertrophy and dysfunction were less frequent in Otud1-CKO mice during TAC treatment, while Otud1 overexpression worsened cardiac hypertrophy and remodeling. METTL3 mediated m6A modification of OTUD1 transcript promoted mRNA stability and elevated protein expression. In terms of pathogenesis, Otud1 plays a crucial role in cardiac hypertrophy by targeting Pgam5, leading to the robust activation of the Ask1-p38/JNK signal pathway to accelerate cardiac hypertrophy. Significantly, the pro-hypertrophy effects of Otud1 overexpression were largely eliminated when Ask1 knockdown. Conclusion: Our findings confirm that targeting the OTUD1-PGAM5 axis holds significant potential as a therapeutic approach for heart failure associated with pathological hypertrophy.

Identification of lysine lactylation (kla)-related lncRNA signatures using XGBoost to predict prognosis and immune microenvironment in breast cancer patients

Breast cancer (BC) stands as a predominant global malignancy, significantly contributing to female mortality. Recently uncovered, histone lysine lactylation (kla) has assumed a crucial role in cancer progression. However, the correlation with lncRNAs remains ambiguous. Scrutinizing lncRNAs associated with Kla not only improves clinical breast cancer management but also establishes a groundwork for antitumor drug development. We procured breast tissue samples, encompassing both normal and cancerous specimens, from The Cancer Genome Atlas (TCGA) database. Utilizing Cox regression and XGBoost methods, we developed a prognostic model using identified kla-related lncRNAs. The model's predictive efficacy underwent validation across training, testing, and the overall cohort. Functional analysis concerning kla-related lncRNAs ensued. We identified and screened 8 kla-related lncRNAs to formulate the risk model. Pathway analysis disclosed the connection between immune-related pathways and the risk model of kla-related lncRNAs. Significantly, the risk scores exhibited a correlation with both immune cell infiltration and immune function, indicating a clear association. Noteworthy is the observation that patients with elevated risk scores demonstrated an increased tumor mutation burden (TMB) and decreased tumor immune dysfunction and exclusion (TIDE) scores, suggesting heightened responses to immune checkpoint blockade. Our study uncovers a potential link between Kla-related lncRNAs and BC, providing innovative therapeutic guidelines for BC management.

A comprehensive molecular characterization of a claudin-low luminal B breast tumor

Breast cancer is the most common cause of death from cancer in women. Here, we present the case of a 43-year-old woman, who received a diagnosis of claudin-low luminal B breast cancer. The lesion revealed to be a poorly differentiated high-grade infiltrating ductal carcinoma, which was strongly estrogen receptor (ER)/progesterone receptor (PR) positive and human epidermal growth factor receptor (HER2) negative. Her tumor underwent in-depth chromosomal, mutational and gene expression analyses. We found a pathogenic protein truncating mutation in the TP53 gene, which is predicted to disrupt its transcriptional activity. The patient also harbors germline mutations in some mismatch repair (MMR) genes, and her tumor displays the presence of immune infiltrates, high tumor mutational burden (TMB) status and the apolipoprotein B mRNA editing enzyme catalytic polypeptide 3 (APOBEC3) associated signatures, which, overall, are predictive for the use of immunotherapy. Here, we propose promising prognostic indicators as well as potential therapeutic strategies based on the molecular characterization of the tumor.

Phosphorylation of USP27X by PIM2 promotes glycolysis and breast cancer progression via deubiquitylation of MYC

Aberrant cell proliferation is a hallmark of cancer, including breast cancer. Here, we show that USP27X is required for cell proliferation and tumorigenesis in breast cancer. We identify a PIM2-USP27X regulator of MYC signaling axis whose activity is an important contributor to the tumor biology of breast cancer. PIM2 phosphorylates USP27X, and promotes its deubiquitylation activity for MYC, which promotes its protein stability and leads to increase HK2-mediated aerobic glycolysis in breast cancer. Moreover, the PIM2-USP27X-MYC axis is also validated in PIM2-knockout mice. Taken together, these findings show a PIM2-USP27X-MYC signaling axis as a new potential target for breast cancer treatment.

Vibrio splendidus infection promotes circRNA-FGL1-regulated coelomocyte apoptosis via competitive binding to Myc with the deubiquitinase OTUB1 in Apostichopus japonicus

Circular RNAs (circRNAs) are involved in various physiological and pathological processes in both vertebrates and invertebrates. However, most studies on circRNAs have focused on their roles as endogenous competitive RNAs. Here, we report a novel function of circRNA derived from the Fibrinogen-like protein 1 gene (circ-FGL1) that inhibits coelomocyte apoptosis via competing with the deubiquitinase AjOTUB1 to bind AjMyc in Apostichopus japonicus during Vibrio splendidus infection. The results showed that circ-FGL1 is significantly downregulated in coelomocytes of V. splendidus-induced A. japonicus and negatively regulates coelomocyte apoptosis through the AjBax-AjCyt c pathway. Mechanistically, the deubiquitinase AjOTUB1 and circ-FGL1 could interact with the transcription factor protein AjMyc in the same region with circ-FGL1/AjMyc having greater affinity. Under normal conditions, high levels of circ-FGL1 bind directly to AjMyc, inhibiting the deubiquitylation of AjMyc by AjOTUB1 and leading to the degradation of AjMyc. After V. splendidus infection, AjMyc disassociates from the depressed expression of circ-FGL1, promoting its deubiquitylation by binding to the induced deubiquitinase AjOTUB1 to inhibit its degradation. AjMyc is then transferred to the nucleus and promotes the transcription of AjCyt c and AjBax to induce coelomocyte apoptosis. The new finding will expand our present outstanding on the functional role of circRNAs and suggest new therapeutic targets for the treatment of echinoderms during bacterial invasion.

Deubiquitinase USP9x regulates the proline biosynthesis pathway in non-small cell lung cancer

Metabolic rewiring has been recognized as a hallmark of malignant transformation, supplying the biosynthetic and energetic demands for rapid cancer cell proliferation and tumor progression. A comprehensive understanding of the regulatory mechanisms governing these metabolic processes is still limited. Here, we identify the deubiquitinase ubiquitin-specific peptidase 9 X-linked (USP9x) as a positive regulator of the proline biosynthesis pathway in non-small cell lung cancer (NSCLC). Our findings demonstrate USP9x directly stabilizes pyrroline-5-carboxylate reductase 3 (PYCR3), a key enzyme in the proline cycle. Disruption of proline biosynthesis by either USP9x or PYCR3 knockdown influences the proline cycle leading to a decreased activity of the connected pentose phosphate pathway and mitochondrial respiration. We show that USP9x is elevated in human cancer tissues and its suppression impairs NSCLC growth in vitro and in vivo. Overall, our study uncovers a novel function of USP9x as a regulator of the proline biosynthesis pathway, which impacts lung cancer growth and progression, and implicates a new potential therapeutic avenue.

Ubiquitination and deubiquitination in cancer: from mechanisms to novel therapeutic approaches

Ubiquitination, a pivotal posttranslational modification of proteins, plays a fundamental role in regulating protein stability. The dysregulation of ubiquitinating and deubiquitinating enzymes is a common feature in various cancers, underscoring the imperative to investigate ubiquitin ligases and deubiquitinases (DUBs) for insights into oncogenic processes and the development of therapeutic interventions. In this review, we discuss the contributions of the ubiquitin-proteasome system (UPS) in all hallmarks of cancer and progress in drug discovery. We delve into the multiple functions of the UPS in oncology, including its regulation of multiple cancer-associated pathways, its role in metabolic reprogramming, its engagement with tumor immune responses, its function in phenotypic plasticity and polymorphic microbiomes, and other essential cellular functions. Furthermore, we provide a comprehensive overview of novel anticancer strategies that leverage the UPS, including the development and application of proteolysis targeting chimeras (PROTACs) and molecular glues.

OTUB1 Targets CHK1 for Deubiquitination and Stabilization to Facilitate Lung Cancer Progression and Radioresistance

PURPOSE

Radioresistance of lung cancer poses a significant challenge when it comes to the treatment of advanced, recurrent, and metastatic cases. Ovarian tumor domain ubiquitin aldehyde binding 1 (OTUB1) is a key member of the deubiquitinase OTU superfamily. This protein is involved in various cellular functions, including cell proliferation, iron death, lipid metabolism, and cytokine secretion as well as immune response processes. However, its specific role and molecular mechanism in lung cancer radioresistance remain to be clarified.

METHODS AND MATERIALS

The expression levels of OTUB1 in paired lung cancer tissues were determined by immunohistochemistry. In vitro and in vivo experiments were conducted to investigate the impact of OTUB1 on the growth and proliferation of lung cancer. Coimmunoprecipitation and Western blotting techniques were performed to examine the interaction between OTUB1 and CHK1. The DNA damage response was measured by comet tailing and immunofluorescence staining. KEGG pathways and Gene Ontology terms were analyzed based on RNA sequencing.

RESULTS

Our findings reveal a high frequency of OTUB1 overexpression, which is associated with an unfavorable prognosis in patients with lung cancer. Through comprehensive investigations, we demonstrate that OTUB1 depletion impairs the process of DNA damage repair and overcomes radioresistance. In terms of the underlying mechanism, our study uncovers that OTUB1 deubiquitinates and stabilizes CHK1, which enhances CHK1 stability, thereby regulating DNA damage and repair. Additionally, we identify CHK1 as the primary downstream effector responsible for mediating the functional effects exerted by OTUB1 specifically in lung cancer. Importantly, OTUB1 has the potential to be a valuable marker for improving the efficacy of radiation therapy for lung adenocarcinoma.

CONCLUSIONS

These findings unveil a novel role for OTUB1 in enhancing radioresistance by deubiquitination and stabilization of the expression of CHK1 in lung cancer and indicate that targeting OTUB1 holds great potential as an effective therapeutic approach for enhancing the efficacy of radiation therapy in lung cancer.

Aerobic glycolysis of vascular endothelial cells: a novel perspective in cancer therapy

Vascular endothelial cells (ECs) are monolayers of cells arranged in the inner walls of blood vessels. Under normal physiological conditions, ECs play an essential role in angiogenesis, homeostasis and immune response. Emerging evidence suggests that abnormalities in EC metabolism, especially aerobic glycolysis, are associated with the initiation and progression of various diseases, including multiple cancers. In this review, we discuss the differences in aerobic glycolysis of vascular ECs under normal and pathological conditions, focusing on the recent research progress of aerobic glycolysis in tumor vascular ECs and potential strategies for cancer therapy.

Targeting deubiquitinase OTUB1 protects vascular smooth muscle cells in atherosclerosis by modulating PDGFRβ

Atherosclerosis is a chronic artery disease that causes various types of cardiovascular dysfunction. Vascular smooth muscle cells (VSMCs), the main components of atherosclerotic plaque, switch from contractile to synthetic phenotypes during atherogenesis. Ubiquitylation is crucial in regulating VSMC phenotypes in atherosclerosis, and it can be reversely regulated by deubiquitinases. However, the specific effects of deubiquitinases on atherosclerosis have not been thoroughly elucidated. In this study, RNAi screening in human aortic smooth muscle cells was performed to explore the effects of OTU family deubiquitinases, which revealed that silencing OTUB1 inhibited PDGF-BB-stimulated VSMC phenotype switch. Further in vivo studies using Apoe-/- mice revealed that knockdown of OTUB1 in VSMCs alleviated atherosclerosis plaque burden in the advanced stage and led to a stable plaque phenotype. Moreover, VSMC proliferation and migration upon PDGF-BB stimulation could be inhibited by silencing OTUB1 in vitro. Unbiased RNA-sequencing data indicated that knocking down OTUB1 influenced VSMC differentiation, adhesion, and proliferation. Mass spectrometry of ubiquitinated protein confirmed that proteins related to cell growth and migration were differentially ubiquitylated. Mechanistically, we found that OTUB1 recognized the K707 residue ubiquitylation of PDGFRβ with its catalytic triad, thereby reducing the K48-linked ubiquitylation of PDGFRβ. Inhibiting OTUB1 in VSMCs could promote PDGFRβ degradation via the ubiquitin-proteasome pathway, so it was beneficial in preventing VSMCs' phenotype switch. These findings revealed that knocking down OTUB1 ameliorated VSMCs' phenotype switch and atherosclerosis progression, indicating that OTUB1 could be a valuable translational therapeutic target in the future.

OTUB1 accelerates hepatocellular carcinoma by stabilizing RACK1 via its non-canonical ubiquitination

BACKGROUND

Dysregulated ubiquitination modification occupies a pivotal role in hepatocellular carcinoma (HCC) tumorigenesis and progression. The ubiquitin aldehyde binding 1 (OTUB1) was aberrantly upregulated and exhibited the pro-tumorigenic function in HCC. However, the underlying mechanisms and responsible targets of OTUB1 remain unclear.

METHODS

First, bioinformatics analysis, western blot and immunohistochemistry staining were applied to analyze OTUB1 expression in HCC specimens. Then, immunoprecipitation assay-tandem mass spectrometry (MS) combined with the gene set enrichment analysis (GSEA) was used to explore the downstream target of OTUB1. Co-immunoprecipitation and ubiquitination assays were used to identify the mechanisms involved. Finally, we explored the regulatory effect of MAZ on OTUB1 through ChIP-qPCR and dual-luciferase reporter assay.

RESULTS

OTUB1 was broadly elevated in HCC tissues and promoted the proliferation and metastasis of HCC in vitro and in vivo. The receptor for activated C kinase 1 (RACK1) performed as a functional partner of OTUB1 and its hyperactivation was associated with aggressive development and other malignant features in HCC by activating oncogenes transcription. Mechanistically, OTUB1 directly bound to RACK1 at its C-terminal domain and decreased the K48-linked ubiquitination of RACK1 through its non-canonical suppression of ubiquitination activity, which stabilized RACK1 protein levels in HCC cells. Therefore, OTUB1 significantly increased multiple oncogenes expression and activated PI3K/AKT and FAK/ERK signaling in a RACK1-dependent manner in HCC. Moreover, the transcription factor MAZ upregulated OTUB1 expression through identifying a putative response element of OTUB1 promoter area.

CONCLUSIONS

Our findings might provide a new therapeutic strategy for HCC by modifying the MAZ-OTUB1-RACK1 axis.

Arecoline promotes Akt-c-Myc-driven aerobic glycolysis in esophageal epithelial cells

Aerobic glycolysis is a typical metabolic rearrangement for tumorigenesis. Arecoline is of explicit carcinogenicity, numerous works demonstrate its mutagenicity, genotoxicity, and cytotoxicity. However, the effects of arecoline on aerobic glycolysis of esophageal epithelial cells remain unclear. In the present study, 5 μM arecoline efficiently increased HK2 expression to induce aerobic glycolysis in Het-1A-Are and NE2-Are cells. The mechanistic analysis showed that arecoline activated the Akt-c-Myc signaling pathway and reduced the GSK3β-mediated phosphorylation of c-Myc on Thr58 to prevent its ubiquitination and destruction, subsequently promoting HK2 transcription and expression. Taken together, these results suggest that arecoline can induce aerobic glycolysis of esophageal epithelial cells and further confirm that arecoline is a carcinogen harmful to human health.

Arginine methylation of ALKBH5 by PRMT6 promotes breast tumorigenesis via LDHA-mediated glycolysis

ALKBH5 is a master regulator of N6-methyladenosine (m6A) modification, which plays a crucial role in many biological processes. Here, we show that ALKBH5 is required for breast tumor growth. Interestingly, PRMT6 directly methylates ALKBH5 at R283, which subsequently promotes breast tumor growth. Furthermore, arginine methylation of ALKBH5 by PRMT6 increases LDHA RNA stability via m6A demethylation, leading to increased aerobic glycolysis. Moreover, PRMT6-mediated ALKBH5 arginine methylation is confirmed in PRMT6-knockout mice. Collectively, these findings identify a PRMT6-ALKBH5-LDHA signaling axis as a novel target for the treatment of breast cancer.

Erianin promotes apoptosis and inhibits Akt-mediated aerobic glycolysis of cancer cells

Highly activated aerobic glycolysis provides the metabolic requirements for tumor cell growth and proliferation. Erianin, a natural product isolated from Dendrobium chrysotoxum Lindl, has been reported to exert antitumor activity in multiple cancers. However, whether Erianin exerts inhibitory effects on aerobic glycolysis and the inherent mechanism remain poorly defined in non-small cell lung cancer (NSCLC). Here, we showed that Erianin inhibited the cell viability and proliferation, and induced apoptosis in NSCLC cells. Moreover, Erianin overtly suppressed aerobic glycolysis via decreasing HK2 expression. Mechanistically, Erianin dose-dependently curbed the Akt-GSK3β signaling pathway phosphorylation activation, which afterwards downregulated HK2 expression. Meanwhile, Erianin inhibited HCC827 tumor growth in vivo. Taken together, our results suggest that the natural product Erianin can suppress aerobic glycolysis and exert potent anticancer effects via the Akt-GSK3β signaling pathway in NSCLC cells.

USP43 stabilizes c-Myc to promote glycolysis and metastasis in bladder cancer

A hallmark of tumor cells, including bladder cancer (BLCA) cells, is metabolic reprogramming toward aerobic glycolysis (Warburg effect). The classical oncogene MYC, which is crucial in regulating glycolysis, is amplified and activated in BLCA. However, direct targeting of the c-Myc oncoprotein, which regulates glycolytic metabolism, presents great challenges and necessitates the discovery of a more clarified regulatory mechanism to develop selective targeted therapy. In this study, a siRNA library targeting deubiquitinases identified a candidate enzyme named USP43, which may regulate glycolytic metabolism and c-Myc transcriptional activity. Further investigation using functional assays and molecular studies revealed a USP43/c-Myc positive feedback loop that contributes to the progression of BLCA. Moreover, USP43 stabilizes c-Myc by deubiquitinating c-Myc at K148 and K289 primarily through deubiquitinase activity. Additionally, upregulation of USP43 protein in BLCA increased the chance of interaction with c-Myc and interfered with FBXW7 access and degradation of c-Myc. These findings suggest that USP43 is a potential therapeutic target for indirectly targeting glycolytic metabolism and the c-Myc oncoprotein consequently enhancing the efficacy of bladder cancer treatment.

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

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

m6A-modified circARHGAP12 promotes the aerobic glycolysis of doxorubicin-resistance osteosarcoma by targeting c-Myc

Chemotherapy resistance accompanied by energy metabolism abnormality functions as one of the main reasons for treatment failure and poor prognosis. However, the function of N6-methyladenosine (m6A)-modified circular RNA (circRNA) on osteosarcoma (OS) is still unclear. Here, present research investigated the potential role and mechanism of circARHGAP12 on OS doxorubicin (Dox) resistance and aerobic glycolysis. Results indicated that circARHGAP12 was a novel m6A-modified circRNA, which was up-regulated in OS cells. Overexpression of circARHGAP12 promoted the Dox resistance half-maximal inhibitory concentration (IC50) and aerobic glycolysis (glucose uptake, lactate and ATP production) in OS cells (Saos-2/Dox, MG63/Dox). Mechanistically, m6A-modified circARHGAP12 could bind with c-Myc mRNA through m6A-dependent manner, thereby enhancing the c-Myc mRNA stability. Thus, these findings revealed the critical function of circARHGAP12 on OS Dox-resistance and aerobic glycolysis. Taken together, our study demonstrated a critical function of circARHGAP12 on OS chemotherapy resistance and energy metabolism abnormality, providing critical roles on OS treatment.

Potential Otubain1 Inhibitor, an Approach for a Treatment against Breast Cancer

The develop of new anticancer drug continues worldwide and one of the new therapeutic targets to reach it is Otubain 1 (OTUB1), since OTUB1 has functions related to prognosis in a variety of tumors and is strongly related to tumor proliferation, migration, and apoptosis by their functions on deubiquitinating. This study uses OTUB1´s active site to develop a specific pharmacological treatment to regulate the OTUB1 functions. The aim of this research was to evaluate the effects of ten compounds (OT1 - OT10), that previously were selected by molecular docking to develop a new anticancer drug to decrease the OTUB1 functions in the cancer processes. We evaluated the cytotoxic effect of OT1 - OT10 compounds on MCF-7, BT474 and MDA-MB 231 cells by MTT assay, and we determined characteristics of apoptosis by western blot analysis. Then, the best compound (OT5) was analyzed by molecular docking, molecular dynamics and theoretical toxicity for describing the interactions of OT5 compound with the OTUB1´s active site. We proposed that the OT5 compound has a high probability to be selective against OTUB1, with an apoptosis (regulating caspase-8) and cytotoxic effect on some cancer lines; IC50 for MCF-7: 97 µM and MDA-MB 231:147 µM, as well as we described that this compound could have specific interactions in the catalytic domain of OTUB1, modifying this protein's activity, decreasing the OTUB1 functions, and probably safe for humans. These results show the high potential of this compound for promoting the development of this compound as a new drug against cancer.

PFKFB3 promotes endometriosis cell proliferation via enhancing the protein stability of β-catenin

Endometriosis is a common inflammatory disease in women of reproductive age and is highly associated with infertility. However, the molecular mechanism of endometriosis remains unclear. 6-Phosphofructose-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) is a key enzyme in glycolysis and plays an important regulatory role in the development of cancer. Here we found that PFKFB3 is highly expressed in endometriotic tissues. PFKFB3 promotes the proliferation and growth of endometriosis cells. Meanwhile, PFKFB3 promotes glycolysis in endometriosis cells. Furthermore, PFKFB3 promotes migration and invasion of endometriosis cells. On this basis, we found that PFKFB3 promotes epithelial-mesenchymal transition (EMT) in endometriosis cells. PFKFB3 interacts with the essential factor of EMT, β-catenin, and promotes the protein stability of β-catenin. In addition, the PFKFB3 inhibitor PFK-015 inhibites the growth of endometriosis cells and the development of endometrial tissue. In conclusion, our study shows that PFKFB3 plays an important role in the development of endometriosis and provides new ideas for the clinical diagnosis or treatment of endometriosis.

Deubiquitinase OTUB1 regulates doxorubicin-induced cardiotoxicity via deubiquitinating c-MYC

BACKGROUND

Doxorubicin (DOX), an anthracycline drug widely used in antitumor therapies, has dose-dependent toxicity that can cause cardiomyocyte apoptosis and oxidative stress, thus limiting its clinical application. OTUB1 (ovarian tumor associated proteinase B1) is an OTU superfamily deubiquitinase that effectively regulates cell proliferation, inflammatory responses, apoptosis, and oxidative stress by specifically removing K48- and K63-linked ubiquitination; however, its role in DOX-induced cardiotoxicity remains unknown.

MATERIALS AND METHODS

A DOX-induced subacute cardiotoxicity mouse model was established by intraperitoneal injection, and cardiac injury was assessed by echocardiography, serum cardiac markers, and histopathological staining. Western blotting, qRT-PCR, and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) immunohistochemistry were used to analyze cell apoptosis, tissue oxidative stress was assessed by superoxide dismutase (SOD) activity, malondialdehyde (MDA), and glutathione peroxidase (GSH-PX) activity. Cell counting kit-8 (CCK-8) assay, TUNEL staining, Western blotting, qRT-PCR, and reactive oxygen species (ROS) flow cytometry were applied on isolated neonatal mice cardiomyocytes to assess apoptosis and oxidative stress. Differentially expressed genes were analyzed using RNA sequencing and clustering analyses. c-MYC inhibitor 10,058-F4 and siRNA targeting c-Myc were used to investigate the roles of c-MYC in OTUB1's regulations of DOX-induced cardiotoxicity. Immunoprecipitation and Western blotting were performed to reveal the deubiquitinating effects of OTUB1 on c-MYC expression.

RESULTS

We found that global Otub1-knockdown in vivo alleviated the subacute DOX treatment-induced cardiac dysfunction, fibrosis, and cardiomyocyte atrophy. Mechanistically, unbiased RNA sequencing and molecular biology experiments revealed that cardiomyocyte apoptosis, inflammation, and oxidative stress in DOX-induced cardiotoxicity were significantly compromised in the Otub1-knockdown group. Further in vitro studies have shown that c-MYC, a critical regulator of apoptosis, is indispensable in OTUB1's regulations of DOX-induced cardiotoxicity. Deubiquitinating effects of OTUB1 on K48- and K63-linked ubiquitination of c-MYC protein are essential for promoting cardiomyocyte apoptosis and oxidative responses.

CONCLUSIONS

OTUB1-c-MYC inhibition protected cardiomyocytes against DOX-induced apoptosis and oxidative stress, suggesting that OTUB1 is a potential translational therapeutic target for preventing DOX-induced cardiotoxicity.

The knockdown of lncRNA DLGAP1-AS2 suppresses osteosarcoma progression by inhibiting aerobic glycolysis via the miR-451a/HK2 axis

Osteosarcoma (OS) is one of the most aggressive bone tumors worldwide. Emerging documents have shown that long noncoding RNAs (lncRNAs) elicit crucial regulatory functions in the process of tumorigenesis. LncRNA DLGAP1-AS2 is recognized as a regulator in several types of cancers, but its biological functions and molecular mechanisms in OS remain to be elucidated. RT-qPCR and In situ hybridization (ISH) were used to evaluate DLGAP1-AS2 expression in OS samples. Western blotting was used for the measurement of the protein levels of hexokinase 2 (HK2) and epithelial-mesenchymal transition (EMT)-related markers. The proliferation of OS cells was determined using a CCK-8 assay and EdU assay. TUNEL assay and flow cytometry were performed to assess OS cell apoptosis. Glucose metabolism in vitro assays were used. The binding relations among miR-451a, HK2, and DLGAP1-AS2 were validated by luciferase reporter assay. The cellular distribution of DLGAP1-AS2 in OS cells was determined by FISH and subcellular fractionation assays. Mouse xenograft models were established to perform the experiments in vivo. We found that DLGAP1-AS2 expression was upregulated in OS tissues and cells. Downregulation of DLGAP1-AS2 expression suppressed the malignancy of OS cells by restraining cell proliferation, the EMT process, invasiveness, migration, and aerobic glycolysis and accelerating apoptotic behaviors. Of note, silenced DLGAP1-AS2 restrained tumor growth and metastasis in vivo. However, DLGAP1-AS2 overexpression accelerated the progression of OS. We further found that DLGAP1-AS2 upregulation was induced by hypoxia and low glucose. Additionally, DLGAP1-AS2 bound to miR-451a to upregulate HK2 expression. Rescue assays revealed that the DLGAP1-AS2/miR-451a/HK2 axis contributed to OS cell malignancy by promoting aerobic glucose metabolism. Overall, these findings revealed a new regulatory pathway where DLGAP1-AS2 upregulated HK2 expression by sponging miR-451a to accelerate OS development.

POH1 facilitates pancreatic carcinogenesis through MYC-driven acinar-to-ductal metaplasia and is a potential therapeutic target

Pancreatic acinar cells undergo acinar-to-ductal metaplasia (ADM), a necessary process for pancreatic ductal adenocarcinoma (PDAC) initiation. However, the regulatory role of POH1, a deubiquitinase linked to several types of cancer, in ADM and PDAC is unclear. In this study, we investigated the role of POH1 in ADM and PDAC using murine models. Our findings suggest that pancreatic-specific deletion of Poh1 alleles attenuates ADM and impairs pancreatic carcinogenesis, improving murine survival. Mechanistically, POH1 deubiquitinates and stabilizes the MYC protein, which potentiates ADM and PDAC. Furthermore, POH1 is highly expressed in PDAC samples, and clinical evidence establishes a positive correlation between aberrantly expressed POH1 and poor prognosis in PDAC patients. Targeting POH1 with a specific small-molecule inhibitor significantly reduces pancreatic tumor formation, highlighting POH1 as a promising therapeutic target for PDAC treatment. Overall, POH1-mediated MYC deubiquitination is crucial for ADM and PDAC onset, and targeting POH1 could be an effective strategy for PDAC treatment, offering new avenues for PDAC targeted therapy.

Lysine lactylation (Kla) might be a novel therapeutic target for breast cancer

BACKGROUND

Histone lysine lactylation (Kla) is a newly identified histone modification, which plays a crucial role in cancer progression. Hence, we determined the prognostic value of Kla in breast cancer (BC).

METHODS

We obtained RNA expression profiles of BC from The Cancer Genome Atlas (TCGA), following screening out Kla-specific genes. Furthermore, we determined the prognostic value of Kla by constructing a cox model based on Kla-specific genes. Subsequently, we identified expression of lactate accumulation-related genes and prognostic Kla-specific genes through Human Protein Atlas (HPA), and further performed a correlation analysis based on their expression. Meanwhile, we explored the effects of Kla on BC tumor microenvironment (TME), drug therapy and immunotherapy. Moreover, we predicted the pathways influenced by Kla via gene set enrichment analysis (GSEA).

RESULTS

A total of 1073 BC samples and 112 normal controls were obtained from TCGA, and 23 tumor samples were removed owing to inadequate clinical information. We identified 257 differentially expressed Kla-specific genes (DEKlaGs) in BC. A cox model involved with CCR7, IGFBP6, NDUFAF6, OVOL1 and SDC1 was established, and risk score could be visualized as an independent biomarker for BC. Meanwhile, Kla was remarkably associated with BC immune microenvironment, drug therapy and immunotherapy. Kla was identified to be related to activation of various BC-related KEGG pathways.

CONCLUSION

In conclusion, Kla contributes to drug resistance and undesirable immune responses, and plays a crucial role in BC prognosis, suggesting that Kla was expected to be a new therapeutic target for BC.

HK2 contributes to the proliferation, migration, and invasion of diffuse large B-cell lymphoma cells by enhancing the ERK1/2 signaling pathway

Hexokinase 2 (HK2) has been associated with carcinogenic growth in numerous kinds of malignancies as essential regulators during the processing of glucose. This study aimed to explore the effects of HK2 on diffuse large B-cell lymphoma (DLBCL) cells via the ERK1/2 signaling. Expressions of HK2 and ERK1/2 were examined in DLBCL cell lines using quantitative reverse transcription polymerase chain reaction and western blotting. HK2 and ERK1/2 were attenuated through HK2 small-interfering RNA (siRNA) and ERK inhibitor FR180204, respectively, in U2932 and SU-DHL-4 cells. Cell Counting Kit-8, clone formation, transwell, and flow cytometry assays were used in evaluating the effects of HK2 and ERK1/2 on cell proliferation, migration, and apoptosis. Moreover, a xenograft model was created to assess the roles of HK2 in vivo. HK2 and ERK1/2 were evidently up-regulated in DLBCL cell lines. HK2 knockdown and FR180204 markedly suppressed the proliferation and clonogenesis of U2932 and SU-DHL-4 cells and promoted cell apoptosis in vitro. We also found that HK2 silencing suppressed tumor growth in vivo. Notably, HK2 knockdown inactivated the ERK1/2 signaling pathway both in vitro and in vivo. These data indicate that inhibition of HK2 may suppress the proliferation, migration, and invasion of DLBCL cells, partly via inhibiting the ERK1/2 signaling pathway.

A BRCA2 germline mutation and high expression of immune checkpoints in a TNBC patient

Triple-negative breast cancer (TNBC) is the most aggressive subtype of mammary carcinoma. Here, we describe a case of an 81-year-old female diagnosed with ductal triple negative breast cancer with a germline pathogenic variant in BReast CAncer gene2 (BRCA2). Genetic testing also revealed the presence of four somatic mutations in the ephrin type-A receptor 3 (EphA3), TP53, BRCA1-associated protein (BAP1), and MYB genes. The BRCA2, TP53, and BAP1 gene mutations are highly predictive of a defective homologous recombination repair system and subsequent chromosomal instability in this patient. Coherently, the patient displayed a strong homologous recombination deficiency signature and high tumor mutational burden status, which are generally associated with increased probability of immune neoantigens formation and presentation, and with tumor immunogenicity. Analysis of immune checkpoint revealed high expression of programmed cell death ligand 1 (PD-L1), programmed cell death ligand 2 (PD-L2), programmed death 1 (PD1), and cytotoxic T-lymphocyte-associated protein 4 (CTLA 4), suggesting that the patient might likely benefit from immunotherapies. Altogether, these findings support an unveiled link between BRCA2 inactivation, HR deficiency and increased expression of immune checkpoints in TNBC. This clinical case highlights the importance of screening TNBC patients for genetic mutations and TMB biomarkers in order to predict the potential efficacy of immunotherapy.

A primary luminal/HER2 negative breast cancer patient with mismatch repair deficiency

Here, we present the case of a 47-year-old woman diagnosed with luminal B breast cancer subtype and provide an in-depth analysis of her gene mutations, chromosomal alterations, mRNA and protein expression changes. We found a point mutation in the FGFR2 gene, which is potentially hyper-activating the receptor function, along with over-expression of its ligand FGF20 due to genomic amplification. The patient also harbors somatic and germline mutations in some mismatch repair (MMR) genes, with a strong MMR mutational signature. The patient displays high microsatellite instability (MSI) and tumor mutational burden (TMB) status and increased levels of CTLA-4 and PD-1 expression. Altogether, these data strongly implicate that aberrant FGFR signaling, and defective MMR system might be involved in the development of this breast tumor. In addition, high MSI and TMB in the context of CTLA-4 and PD-L1 positivity, suggest the potential benefit of immune checkpoint inhibitors. Accurate characterization of molecular subtypes, based on gene mutational and expression profiling analyses, will be certainly helpful for individualized treatment and targeted therapy of breast cancer patients, especially for those subtypes with adverse outcome.

OTUB1's role in promoting OSCC development by stabilizing RACK1 involves cell proliferation, migration, invasion, and tumor-associated macrophage M1 polarization

Ovarian tumor domain, ubiquitin aldehyde binding 1 (OTUB1), a deubiquitinating enzyme known to regulate the stability of downstream proteins, has been reported to regulate various cancers tumorigenesis, yet its direct effects on oral squamous cell carcinoma (OSCC) progression are unclear. Bioinformatics analysis was performed to screen for genes of interest, and in vitro and in vivo studies were carried out to investigate the function and mechanism of OTUB1 in OSCC. We found that OTUB1 was abnormally elevated in OSCC tissues and positively associated with the pathological stage and tumor stage. Knockdown of OTUB1 impaired the malignance of OSCC cells - suppressed cell proliferation, invasion, migration, and xenografted tumor growth. OTUB1 silencing also drove tumor-associated macrophage M1 polarization but suppressed M2 polarization, and the induction of M1 polarization inhibited the survival of OSCC cells. However, OTUB1 overexpression exerted the opposite effects. Furthermore, the protein network that interacted with the OTUB1 protein was constructed based on the GeneMANIA website. Receptor for activated C kinase 1 (RACK1), a facilitator of OSCC progression, was identified as a potential target of the OTUB1 protein. We revealed that OTUB1 positively regulated RACK1 expression and inhibited RACK1 ubiquitination. Additionally, RACK1 upregulation reversed the effects of OTUB1 knockdown on OSCC progression. Overall, we demonstrated that OTUB1 might regulate OSCC progression by maintaining the stability of the RACK1 protein. These findings highlight the potential roles of the OTUB1/RACK1 axis as a potential therapeutic target in OSCC.

Molecular profile of non-coding RNA-mediated glycolysis control in human cancers

The glycolysis is a common characteristic of cancer and it is responsible for providing enough energy to ensure growth. The glycolysis suppression is beneficial in tumor growth reduction. The stimulation/inhibition of glycolysis in cancer is tightly regulated by ncRNAs. The regulation of glycolysis by ncRNAs can influence proliferation and therapy response of tumor. The miRNAs are capable of inactivating enzymes responsible for glycolysis and suppressing signaling networks resulting in glycolysis induction. By regulation of glycolysis, miRNAs can affect therapy response. The lncRNAs and circRNAs follow a same pathway and by targeting glycolysis, they affect progression and therapy response of tumor. Noteworthy, lncRNAs and circRNAs sponge miRNAs in glycolysis mechanism control in tumor cells. Furthermore, ncRNA-mediated regulation of glycolysis mechanism can influence metastasis to organs of body. The ncRNAs regulating glycolysis are reliable biomarkers in cancer patients and more importantly, exosomal ncRNAs due to their presence in body fluids, are minimally-invasive biomarkers.

FDX1 enhances endometriosis cell cuproptosis via G6PD-mediated redox homeostasis

Cuproptosis is a new form of programmed cell death, which is associated with the mitochondrial TCA (tricarboxylic acid) cycle. But the functions of cuproptosis in endometriosis progression are still unknown. Here, we find that cuproptosis suppresses the growth of endometriosis cells and the growth of ectopic endometrial tissues in a mouse model. FDX1 as a key regulator in cuproptosis pathway could promote cuproptosis in endometriosis cells. Interestingly, FDX1 interacts with G6PD, and reduces its protein stability, which predominantly affects the cellular redox-regulating systems. Then, the reduced G6PD activity enhances cuproptosis via down-regulating NADPH and GSH levels. Collectively, our study demonstrates that FDX1 mediates cuproptosis in endometriosis via G6PD pathway, resulting in repression of endometriosis cell proliferation and metastasis.