USP27-mediated Cyclin E stabilization drives cell cycle progression and hepatocellular tumorigenesis

USP27 promotes glycolysis and hepatocellular carcinoma progression by stabilizing PFKFB3 through deubiquitination

Hepatocellular carcinoma (HCC) is associated with a dismal prognosis, primarily due to its high rates of metastasis and recurrence. Metabolic reprogramming, specifically enhanced glycolysis, is a prominent feature of cancer progression. This study identifies ubiquitin-specific peptidase 27 X-linked (USP27) as a significant regulator of glycolysis in HCC. We demonstrate that USP27 stabilizes PFKFB3, a key glycolytic enzyme, through deubiquitination, thereby increasing glycolytic activity and facilitating tumor progression. Furthermore, we reveal that CTCF, a well-known transcription factor, directly binds to the USP27 promoter and upregulates its expression, thereby establishing a connection between transcriptional regulation and metabolic reprogramming in HCC. Knockdown of USP27 or CTCF in HCC cells considerably decreased glycolysis and proliferation, while overexpression had the opposite effect. In vivo studies confirmed that USP27 knockdown suppresses HCC growth and metastasis. Our findings establish the CTCF/USP27/PFKFB3 axis as a novel mechanism driving HCC progression through glycolysis, indicating that targeting this pathway could offer new therapeutic opportunities. These results provide valuable insights into the molecular mechanisms underlying HCC and emphasize the potential of targeting USP27-mediated metabolic pathways as a strategy for cancer treatment.

MiR-214 promotes the antitumor effect of NK cells in colorectal cancer liver metastasis through USP27X/Bim

Colorectal cancer (CRC) is a common tumor type, and liver metastasis reduces the long-term survival in CRC patients. Natural killer (NK) cells play an important role in anti-tumor immunity. The aim of this study was to investigate the mechanism of miR-214-5p on NK cells in CRC liver metastasis. We collected clinical samples of CRC liver metastasis and nonmetastatic tissues and purchased the human NK cell lines NK92 and liver metastatic CRC cells KM12L4 for research. RT‒qPCR, Western blot, CCK-8, Transwell, and flow cytometry methods were used to evaluate the effect of miR-214-5p/USP27X/Bim pathway regulating NK cell activity on CRC liver metastasis. In addition, we also investigated the potential targets and regulatory mechanisms of the signaling pathway of miR-214-5p. In this study, we found that miR-214-5p was downregulated in CRC liver metastasis tissues. After transfection of miR-214-5p mimic, the activity of NK cells was significantly enhanced, and the proliferation and migration ability of CRC liver metastasis cells were inhibited, while inducing tumor cell apoptosis. Further research proved that USP27X is a potential target for miR-214-5p and upregulates Bim level through deubiquitination. In addition, miR-214-5p mimic reduced the level of USP27X and Bim, thereby enhancing the antitumor effect of NK cells. In conclusion, our research results show that miR-214-5p promotes the antitumor effect of NK cells by regulating the USP27X/Bim pathway, thereby inhibiting CRC liver metastasis. This finding reveals the important role of miR-214-5p in regulating the immune function of NK cells, and provides new ideas for developing new immunotherapy strategies.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10616-024-00642-1.

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.

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.

Dysregulation of deubiquitination in breast cancer

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

USP27X variants underlying X-linked intellectual disability disrupt protein function via distinct mechanisms

Neurodevelopmental disorders with intellectual disability (ND/ID) are a heterogeneous group of diseases driving lifelong deficits in cognition and behavior with no definitive cure. X-linked intellectual disability disorder 105 (XLID105, #300984; OMIM) is a ND/ID driven by hemizygous variants in the USP27X gene encoding a protein deubiquitylase with a role in cell proliferation and neural development. Currently, only four genetically diagnosed individuals from two unrelated families have been described with limited clinical data. Furthermore, the mechanisms underlying the disorder are unknown. Here, we report 10 new XLID105 individuals from nine families and determine the impact of gene variants on USP27X protein function. Using a combination of clinical genetics, bioinformatics, biochemical, and cell biology approaches, we determined that XLID105 variants alter USP27X protein biology via distinct mechanisms including changes in developmentally relevant protein-protein interactions and deubiquitylating activity. Our data better define the phenotypic spectrum of XLID105 and suggest that XLID105 is driven by USP27X functional disruption. Understanding the pathogenic mechanisms of XLID105 variants will provide molecular insight into USP27X biology and may create the potential for therapy development.

Inhibition of SIRT7 promotes STAT1 activation and STAT1-dependent signaling in hepatocellular carcinoma

The signal transducer and activator of transcription 1 (STAT1) plays a crucial role in regulating tumor progression. However, the mechanisms governing its phosphorylation and biological functions remain incompletely understood. Here, we present compelling evidence indicating that knockdown of SIRT7 inhibits Smurf1-induced ubiquitination of STAT1, consequently impeding the proteasome pathway degradation of STAT1. This inhibition leads to increased stability of STAT1 and enhanced binding to JAK1. Importantly, SIRT7 exerts a negative regulatory effect on STAT1 activation and IFN-γ/STAT1 signaling in hepatocellular carcinoma (HCC). Etoposide treatment not only facilitates STAT1 activation but also downregulates SIRT7 expression. Notably, knockdown of STAT1 in SIRT7-deficient cells attenuates the increase in cell apoptosis induced by Etoposide treatment. In conclusion, our data shed light on the intricate interplay between ubiquitination, STAT1, SIRT7, and Smurf1, elucidating their impact on STAT1-related signaling. These insights contribute to a more comprehensive understanding of the molecular mechanisms involved in STAT1 regulation and suggest potential avenues for the development of targeted therapies against cancer.

Deubiquitylating Enzymes in Cancer and Immunity

Deubiquitylating enzymes (DUBs) maintain relative homeostasis of the cellular ubiquitome by removing the post-translational modification ubiquitin moiety from substrates. Numerous DUBs have been demonstrated specificity for cleaving a certain type of ubiquitin linkage or positions within ubiquitin chains. Moreover, several DUBs perform functions through specific protein-protein interactions in a catalytically independent manner, which further expands the versatility and complexity of DUBs' functions. Dysregulation of DUBs disrupts the dynamic equilibrium of ubiquitome and causes various diseases, especially cancer and immune disorders. This review summarizes the Janus-faced roles of DUBs in cancer including proteasomal degradation, DNA repair, apoptosis, and tumor metastasis, as well as in immunity involving innate immune receptor signaling and inflammatory and autoimmune disorders. The prospects and challenges for the clinical development of DUB inhibitors are further discussed. The review provides a comprehensive understanding of the multi-faced roles of DUBs in cancer and immunity.

Phosphorylation of USP27X by GSK3β maintains the stability and oncogenic functions of CBX2

Chromobox protein homolog 2 (CBX2) exerts a multifaceted impact on the progression of aggressive cancers. The proteasome-dependent pathway is crucial for modulating CBX2 regulation, while the specific regulatory roles and mechanisms of deubiquitinating enzymes targeting CBX2 remain poorly understood. Mass spectrometry analysis identified ubiquitin-specific peptidase 27X (USP27X) as a deubiquitinating enzyme that targets CBX2. Overexpression of USP27X significantly enhances CBX2 levels by promoting deubiquitination, while deficiency of USP27X leads to CBX2 degradation, thereby inhibiting tumorigenesis. Furthermore, it has been revealed that glycogen synthase kinase 3 beta (GSK3β) can directly bind to and phosphorylate USP27X, thereby enhancing the interaction between USP27X and CBX2 and leading to further stabilization of the CBX2 protein. Clinically, the co-expression of high levels of USP27X and CBX2 in breast cancer tissues is indicative of a poor prognosis for patients with this disease. These findings collectively underscore the critical regulatory role played by USP27X in modulating CBX2, thereby establishing the GSK3β-USP27X-CBX2 axis as a pivotal driver of malignant progression in breast cancer.

Therapeutic Potential of Nanomedicine in Management of Alzheimer's Disease and Glioma

Neoplasm (Glioblastoma) and Alzheimer's disease (AD) comprise two of the most chronic psychological ailments. Glioblastoma is one of the aggressive and prevalent malignant diseases characterized by rapid growth and invasion resulting from cell migration and degradation of extracellular matrix. While the latter is characterized by extracellular plaques of amyloid and intracellular tangles of tau proteins. Both possess a high degree of resistance to treatment owing to the restricted transport of corresponding drugs to the brain protected by the blood-brain barrier (BBB). Development of optimized therapies using advanced technologies is a great need of today. One such approach is the designing of nanoparticles (NPs) to facilitate the drug delivery at the target site. The present article elaborates the advances in nanomedicines in treatment of both AD as well as Gliomas. The intention of this review is to provide an overview of different types of NPs with their physical properties emphasizing their importance in traversing the BBB and hitting the target site. Further, we discuss the therapeutic applications of these NPs along with their specific targets. Multiple overlapping factors with a common pathway in development of AD and Glioblastoma are discussed in details that will assist the readers in developing the conceptual approach to target the NP for an aging population in the given circumstances with limitations of currently designed NPs, and the challenges to meet and the future perspectives.

High expression of BHLHE40 promotes immune infiltration and tumor progression in thyroid cancer

Thyroid cancer (THCA) is a common malignancy of the endocrine system which threatens people's health and life quality. It is urgent to find the marker gene of THCA. BHLHE40 is a key gene involved in tumor malignant progression. However, the role of BHLHE40 in THCA remains unclear. In this study, 346 upregulated and 302 downregulated genes were found by analyzing the Gene Expression Omnibus database. BHLHE40 was upregulated in THCA. BHLHE40 and its related differentially expressed genes were involved in cell adhesion and differentiation in THCA. Moreover, BHLHE40 was also highly expressed in THCA cells and tissues. Downregulation of BHLHE40 inhibited cell growth and metastasis. Knockdown of BHLHE40 conditioned media retarded cell migration in M2 macrophages. In addition, knockdown of BHLHE40 inhibited CD206 and CD163 expression and decreased the secretion of interleukin-10 in M2 macrophage. Therefore, BHLHE40 has the potential to be used as a biomarker of immune infiltration and tumorigenesis in THCA.

Regulation of Cyclin D1 Degradation by Ubiquitin-Specific Protease 27X Is Critical for Cancer Cell Proliferation and Tumor Growth

Cyclin D1 (CCND1) is a critical regulator of cell proliferation and its overexpression has been linked to the development and progression of several malignancies. CCND1 overexpression is recognized as a major mechanism of therapy resistance in several cancers; tumors that rely on CCND1 overexpression to evade cancer therapy are extremely sensitive to its ablation. Therefore, targeting CCND1 is a promising strategy for preventing tumor progression and combating therapy resistance in cancer patients. Although CCND1 itself is not a druggable target, it can be targeted indirectly by inhibiting its regulators. CCND1 steady-state levels are tightly regulated by ubiquitin-mediated degradation, and defects in CCND1 ubiquitination are associated with increased CCND1 protein levels in cancer. Here, we uncover a novel function of ubiquitin-specific protease 27X (USP27X), a deubiquitinating enzyme (DUB), in regulating CCND1 degradation in cancer. USP27X binds to and stabilizes CCND1 in a catalytically dependent manner by negatively regulating its ubiquitination. USP27X expression levels correlate with the levels of CCND1 in several HER2 therapy-resistant breast cancer cell lines, and its ablation leads to a severe reduction of CCND1 protein levels, inhibition of tumor growth, and resensitization to targeted therapy. Together, the results presented in our study are the first to expose USP27X as a major CCND1 deubiquitinase and provide a mechanistic explanation for how this DUB fosters tumor growth.

IMPLICATIONS

As a deubiquitinating enzyme, USP27X is a druggable target. Our study illuminates new avenues for therapeutic intervention in CCND1-driven cancers.

Identification of KIF21B as a Biomarker for Colorectal Cancer and Associated with Poor Prognosis

OBJECTIVE

This study is aimed at exploring the function of KIF21B in colorectal cancer.

METHODS

The expression of KIF21B was analyzed by the UALCAN database, GEPIA site, and TIMER site. The survival rate was analyzed by Kaplan-Meier curves, and the prognosis was analyzed by ROC. Relevant signaling pathways and biological processes were analyzed by GO-KEGG enrichment analysis. The correlation between KIF21B and cancer immune infiltrates was analyzed by TIMER. The functional state of KIF21B in various types of cancers was conducted by single-cell RNA-sequencing. Furthermore, the expression of KIF21B was verified by real-time qPCR and Western blotting. The cell proliferation was measured by CCK8 assay. The cell apoptosis was analyzed by flow cytometry. Cell migration and invasion were determined by the transwell assay.

RESULTS

Combination analysis of bioinformatics methods revealed that KIF21B is high expression in CRC, associated with poor survival. KIF21B and associated genes were significantly enriched in covalent chromatin modification. The expression of KIF21B was positively correlated with infiltrating levels of CD4+ T cells and neutrophils, cell apoptosis, and metastasis. KIF21B was upregulated expression in CRC cell lines. KIF21B deficiency reduced cell proliferation, migration, and invasion.

CONCLUSIONS

Our study suggested that KIF21B may be a biomarker in CRC.

Candesartan Reduces Neuronal Apoptosis Caused by Ischemic Stroke via Regulating the FFAR1/ITGA4 Pathway

Ischemic stroke (IS) is a general term for necrosis of brain tissue caused by stenosis, occlusion of arteries supplying blood to the brain (carotid artery and vertebral artery), and insufficient blood supply to the brain. Cerebral ischemia is the main kind of IS causing cell damage. However, the underlying mechanism still needs to be clarified further. In this study, it was demonstrated that FFAR1 was a hub gene in IS. The expression of FFAR1 was increased in PC12 cells with OGD/R treatment. FFAR1 deficiency inhibited cell viability and induced cell apoptosis, which was reversed by FFAR1 overexpression. Moreover, candesartan, as a compound targeting FFAR1, facilitated cell viability and reduced cell apoptosis. The expression of ITGA4 was also high in OGD/R-PC12 cells as FFAR1. Furthermore, FFAR1 deficiency retarded the increasing of cell viability and inhibition of cell apoptosis by downregulation of Bax and Cleaved Caspase-3 in OGD/R-PC12 cells with candesartan treatment. In conclusion, candesartan may regulate neuronal apoptosis through FFAR1/ITGA4 axis.

MiR-19a suppresses ferroptosis of colorectal cancer cells by targeting IREB2

Colorectal cancer (CRC) is the most common malignant tumor occurred in digestive system. However, the prognosis of CRC patients is poor. Therefore, it is urgent to illuminate the mechanism suppressing CRC and explore novel targets or therapies for CRC treatment. MicroRNAs (miRNAs) are a class of non-coding RNAs with a length of 20–23 nucleotides encoded by endogenous genes, which are associated with the development of a variety of cancers, including CRC. Studies have shown that miR-19a is identified as oncogenic miRNA and promotes the proliferation, migration and invasion of CRC cells. However, the relationship between miR-19a and ferroptosis in CRC remains unknown. Here, we reported that iron-responsive element-binding protein 2 (IREB2), as an inducer of ferroptosis, was negatively regulated by miR-19a. IREB2 is a direct target of miR-19a. In addition, ferroptosis was suppressed by miR-19a through inhibiting IREB2. Thus, we proposed a novel mechanism of ferroptosis mediated by miR-19a in CRC cells, which could give rise to a new strategy for the therapy of CRC.

Pathological implication of protein post-translational modifications in cancer

Protein post-translational modifications (PTMs) profoundly influence protein functions and play crucial roles in essentially all cell biological processes. The diverse realm of PTMs and their crosstalk is linked to many critical signaling events involved in neoplastic transformation, carcinogenesis and metastasis. The pathological roles of various PTMs are implicated in all aspects of cancer hallmark functions, cancer metabolism and regulation of tumor microenvironment. Study of PTMs has become an important area in cancer research to understand cancer biology and discover novel biomarkers and therapeutic targets. With a limited scope, this review attempts to discuss some PTMs of high frequency with recognized importance in cancer biology, including phosphorylation, acetylation, glycosylation, palmitoylation and ubiquitination, as well as their implications in clinical applications. These protein modifications are among the most abundant PTMs and profoundly implicated in carcinogenesis.

Knockdown of mitochondrial threonyl-tRNA synthetase 2 inhibits lung adenocarcinoma cell proliferation and induces apoptosis

Lung cancer is a significant global burden. Aminoacyl-tRNA synthetases (aaRSs) can be reliably identified by the occurrence and improvement of tumors. Threonyl-tRNA synthetase (TARS) and mitochondrial threonyl-tRNA synthetase 2 (TARS2) are both aaRSs. Many studies have shown that TARS are involved in tumor angiogenesis and metastasis. However, TARS2 has not yet been reported in tumors. This study explored the role of TARS2 in the proliferation and apoptosis of lung adenocarcinoma (LUAD). TARS2 expression in lung adenocarcinoma and non-cancerous lung tissues was detected via immunohistochemistry. Cell proliferation was detected using MTS, clone formation, and EdU staining assays. Flow cytometry was used to detect cell cycle, mitochondria reactive oxygen species (mROS) production, and apoptosis. Mitochondrial membrane potential (MMP ΔΨm) was detected using JC-1 fluorescent probes. Cell cycle, apoptosis-related pathway, and mitochondrial DNA (mtDNA) -encoded protein expression was detected via Western blotting. Finally, the effect of TARS2 on tumor growth was examined using a xenotransplanted tumor model in nude mice. We found that TARS2 was highly expressed in lung adenocarcinoma tissues and associated with poor overall survival (OS). Mechanistic analysis showed that knockdown of TARS2 inhibited proliferation through the retinoblastoma protein (RB) pathway and promoted mROS-induced apoptosis. Knockdown of TARS2 inhibits tumor growth in a xenotransplanted tumor model. TARS2 plays an important role in LUAD cell proliferation and apoptosis and may be a new therapeutic target.

FUNDC1 induces apoptosis and autophagy under oxidative stress via PI3K/Akt/mTOR pathway in cataract lens cells

OBJECTIVE

This purpose of the study is to explore the mRNA and protein expression of FUNDC1 in cataract cells and tissues, clarify the function and mechanism of FUNDC1 in cataract cells under oxidative stress.

METHODS

We used bioinformatic analysis to screen DEGs in cataract from GSE153933. The expression of FUNDC1 in cataract specimens and cells was measured by RT-qPCR and western blotting. MethPrimer was used to predict CpG island of FUNDC1 promoter. The methylation of FUNDC1 in cataract specimens and cells was determined by MSP assay. Flow cytometry assay was used to measure cell apoptosis in FUNDC1-knockdown and -overexpression SRA01/04 cells. The expression of LC3 was analyzed by immunofluorescence assay. The expression of apoptosis related proteins, autophagy and PI3K/Akt/mTOR related proteins was determined by western blotting.

RESULTS

The results of bioinformatic analysis revealed that FUNDC1 was upregulation in cataract. FUNDC1 was further high expression in SRA01/04 cells with H₂O₂ treatment whereas hypomethylation of FUNDC1 in cataract lens cells under oxidative stress. Knockdown of FUNDC1 decreased cell apoptosis and autophagy compared with negative control of SRA01/04 cells. While overexpression of FUNDC1 elevated cell apoptosis and autophagy compared to empty vector group in SRA01/04 cells. Mechanically, FUNDC1 reduced the phosphorylation of PI3K/Akt/mTOR pathway under oxidative stress in SRA01/04 cells.

CONCLUSION

Our study suggested that FUNDC1 deficiency restrains cell apoptosis and autophagy through inhibiting PI3K/Akt/mTOR signal pathway.

MT1G inhibits the growth and epithelial-mesenchymal transition of gastric cancer cells by regulating the PI3K/AKT signaling pathway

Gastric carcinoma (GC) is a malignant tumor that has high mortality and morbidity worldwide. Although many efforts have been focused on the development and progression of GC, the underlying functional regulatory mechanism of GC needs more clarification. Metallothionein 1G (MT1G) is a member of the metallothionein family (MTs), and hypermethylation of MT1G occurred in a variety of cancers, including gastric cancer. However, the functional mechanism of MT1G in GC remains unclear. Here, we demonstrated that MT1G was down-regulated in GC tissues and cells. Overexpression of MT1G inhibited cell proliferation, foci formation and cell invasion, while knockdown of MT1G increased cell proliferation, foci formation and cell invasion. In addition, MT1G overexpression inhibited cell cycle progression and MT1G deficiency exerted opposite phenotype. p-AKT was negatively regulated by MT1G. In summary, our study reveals that MT1G exerts crucial role in regulating of cell proliferation and migration of gastric cancer, providing new insights for MT1G-related pathogenesis and a basis for developing new strategies for treatment of GC.

GADD45A induces neuropathic pain by activating P53 apoptosis pathway in mice

BACKGROUND

Neuropathic pain is a common condition with current heights of varying etiology. The therapeutic drugs are also poorly work and often limited by side effects such as dizziness.

OBJECTIVE

This study aimed to explore the function mechanism of GADD45A in neuropathic pain.

METHODS

The DEGs in neuropathic pain mouse model chip were screened by bioinformatics analysis. The expression of GADD45A in SNL model was determined by RT-qPCR and Immunofluorescence assay. The protein expression of p53-apoptosis pathway proteins was determined by western blotting.

RESULTS

Combination analysis of bioinformatics methods revealed that the expression of GADD45A was upregulated in SNL. The results of RT-qPCR assay and Immunofluorescence assay revealed that GADD45A was overexpressed in all of time points SNL model. Furthermore, knockdown of GADD45A in SNL remarkably antagonized the malignance phenotype compared with the Ad-GFP treated SNL. In addition, knockdown of GADD45A downregulated the expression of p53 and reduced the apoptosis of spinal cord nerve cells.

CONCLUSIONS

Our study suggests that GADD45A may be a biomarker in the neuropathic pain of mice.

SLC3A2 inhibits ferroptosis in laryngeal carcinoma via mTOR pathway

Objective

This study aimed to explore the mRNA and protein expression of SLC3A2 in laryngeal carcinoma cells and tissues, and functional regulatory mechanism of SLC3A2 in cell ferroptosis of laryngeal carcinoma.

Methods

We chose the key gene-SLC3A2 of DEGs from TCGA by bioinformatics analysis, and then we constructed stable knockdown of SLC3A2 in laryngeal carcinoma cells. MTT assay and clonogenic assay were used to determine cell viability and cell growth, respectively. The mRNA and protein expression were determined by RT-qPCR and western blotting, respectively. Xenograft tumor model was used to determine the role of SLC3A2 in tumor growth.

Results

The results of limma analysis recovered that 92 genes were involved in both upregulated DEGs and high risk of poor prognosis, whereas 36 genes were involved in both downregulated DEGs and low risk of poor prognosis. Pathway enrichment analysis indicated that mTOR signaling pathway and ferroptosis exerted a role in regulating these intersection genes. Moreover, SLC3A2 is a key gene in ferroptosis in laryngeal carcinoma. SLC3A2 is highly expressed in laryngeal carcinoma tissues and cells. Patients with high SLC3A2 expression exerted poor survival. SLC3A2 deficiency inhibited cell proliferation and foci formation. Furthermore, knockdown of SLC3A2 expression induced the efficacy of ferroptosis and suppressed ferroptosis related proteins expression. Mechanically, SLC3A2 deficiency facilitated ferroptosis through upregulating the expression of mTOR and P70S6K, whereas inhibited p-mTOR and p-P70S6K expression in laryngeal carcinoma cells. SLC3A2 deficiency inhibited tumorigenesis in nude mice.

Conclusion

Our study suggests that SLC3A2 negatively regulates ferroptosis through mTOR pathway in laryngeal carcinoma.

The deubiquitinase Usp27x as a novel regulator of cFLIPL protein expression and sensitizer to death-receptor-induced apoptosis

Death receptors are transmembrane proteins that can induce the activation of caspase-8 upon ligand binding, initiating apoptosis. Recent work has highlighted the great molecular complexity of death receptor signalling, in particular through ubiquitination/deubiquitination. We have earlier defined the deubiquitinase Ubiquitin-Specific Protease 27x (Usp27x) as an enzyme capable of stabilizing the pro-apoptotic Bcl-2 family member Bim. Here, we report that enhanced expression of Usp27x in human melanoma cells leads to the loss of cellular FLICE-like inhibitory protein (cFLIP) and sensitizes to Tumor necrosis factor receptor 1 (TNF-R1) or Toll-like receptor 3 (TLR3)-induced extrinsic apoptosis through enabling enhanced processing of caspase-8. The loss of cFLIP_L upon overexpression of Usp27x was not due to reduced transcription, could be partially counteracted by blocking the ubiquitin proteasome system and was independent of the known cFLIP_L destabilizing ubiquitin E3-ligases Itch and DTX1. Instead, Usp27x interacted with the E3-ligase TRIM28 and reduced ubiquitination of TRIM28. Reduction of cFLIP_L protein levels by Usp27x-induction depended on TRIM28, which was also required for polyI:C-induced cell death. This work defines Usp27x as a novel regulator of cFLIP_L protein expression and a deubiquitinase in fine tuning death receptor signalling pathways to execute apoptosis.

Stabilization of SETD3 by deubiquitinase USP27 enhances cell proliferation and hepatocellular carcinoma progression

The histone methyltransferase SETD3 plays critical roles in various biological events, and its dysregulation is often associated with human diseases including cancer. However, the underlying regulatory mechanism remains elusive. Here, we reported that ubiquitin-specific peptidase 27 (USP27) promotes tumor cell growth by specifically interacting with SETD3, negatively regulating its ubiquitination, and enhancing its stability. Inhibition of USP27 expression led to the downregulation of SETD3 protein level, the blockade of the cell proliferation and tumorigenesis of hepatocellular carcinoma (HCC) cells. In addition, we found that USP27 and SETD3 expression is positively correlated in HCC tissues. Notably, higher expression of USP27 and SETD3 predicts a worse survival in HCC patients. Collectively, these data elucidated that a USP27-dependent mechanism controls SETD3 protein levels and facilitates its oncogenic role in liver tumorigenesis.

Integral membrane protein 2A enhances sensitivity to chemotherapy via notch signaling pathway in cervical cancer

As the second most common cancer among women, cervical cancer is a huge threat to their health all over the world. Integral membrane protein 2A (ITM2A), a member of the Type II Integral Membrane protein (ITM2) family, has been reported to act as a tumor suppressor in breast cancer and ovarian cancer. Moreover, the low expression of ITM2A was associated with cervical adenocarcinoma. However, the function of ITM2A in drug resistance in cervical cancer remains unclear. Here, we used bioinformatics methods to screen differentially expressed genes (DEGs) closely related to chemotherapeutic relapse cervical carcinoma. ITM2A is downregulated in cervical tumor tissues and is associated with poor survival. Furthermore, ITM2A is also downregulated in cervical cancer cells with cisplatin resistance. Overexpression of ITM2A increases the cisplatin sensitivity of cervical cancer cells. Mechanically, ITM2A upregulation mediates the sensitivity of cervical cancer cell through Notch signaling pathway. Our study suggests that ITM2A may serve as a target in mediating cisplatin-resistant cervical cancer.

SLC34A2 promotes cancer proliferation and cell cycle progression by targeting TMPRSS3 in colorectal cancer

Solute carrier family 34 member 2 (SLC34A2), a family member of sodium-driven phosphate cotransporters, has been reported to facilitate cell proliferation and tumor growth. However, the functional mechanism by which SLC34A2 promotes cell growth and cell cycle progression remains poorly understood. Here, we reported that SLC34A2 was overexpressed in CRC by analysis of TCGA and GEO datasets. A total of 45 differentially expressed genes (DEGs) were identified from comparing SLC34A2-high or -low groups and functional enrichment analysis of these DEGs demonstrated that cell cycle pathway was enriched. Interestingly, we found a positive correlation between TMPRSS3 (transmembrane serine protease 3) and SLC34A2, which was confirmed by RT-qPCR and western blotting. Furthermore, TMPRSS3 was also upregulated in CRC tumor tissues compared to normal tissues. Patients with high TMPRSS3 expression had poor prognosis. Functionally, TMPRSS3 deficiency inhibited cell proliferation and colony formation in CRC cells. TMPRSS3 overexpression in SLC34A2-deficient cells antagonized siSLC34A2-mediated cell cycle inhibition by promoting cyclin E, cyclin A protein expression. Based on these results, our study suggests that SLC34A2 promotes cancer proliferation and cell cycle progression by targeting TMPRSS3 in colorectal cancer cells.

Overexpression of the Ubiquitin Specific Proteases USP43, USP41, USP27x and USP6 in Osteosarcoma Cell Lines: Inhibition of Osteosarcoma Tumor Growth and Lung Metastasis Development by the USP Antagonist PR619

Osteosarcoma (OS) is the most common malignant bone tumor in children and teenagers. In many cases, such as poor response to treatment or the presence of metastases at diagnosis, the survival rate of patients remains very low. Although in the literature, more and more studies are emerging on the role of Ubiquitin-Specific Proteases (USPs) in the development of many cancers, few data exist regarding OS. In this context, RNA-sequencing analysis of OS cells and mesenchymal stem cells differentiated or not differentiated into osteoblasts reveals increased expression of four USPs in OS tumor cells: USP6, USP27x, USP41 and USP43. Tissue microarray analysis of patient biopsies demonstrates the nucleic and/or cytoplasmic expression of these four USPs at the protein level. Interestingly, Kaplan–Meyer analysis shows that the expression of two USPs, USP6 and USP41, is correlated with patient survival. In vivo experiments using a preclinical OS model, finally demonstrate that PR619, a USP inhibitor able to enhance protein ubiquitination in OS cell lines, reduces primary OS tumor growth and the development of lung metastases. In this context, in vitro experiments show that PR619 decreases the viability of OS cells, mainly by inducing a caspase3/7-dependent cell apoptosis. Overall, these results demonstrate the relevance of targeting USPs in OS.

CKS2 Promotes the Growth in Non-Small-Cell Lung Cancer by Downregulating Cyclin-Dependent Kinase Inhibitor

INTRODUCTION/OBJECTIVE

This study aimed to explore the expression of cyclin-dependent kinase subunit 2 (CKS2) in tissues and cells in non-small-cell lung cancer (NSCLC) and the function mechanism of CKS2 in NSCLC cell growth and tumorigensis.

METHODS

After transfecting NCI-H2170 cells with short-hair RNA (shRNA), an shCKS2 gene-silencing model was established. The cells were divided into a shRNA group and shNC group. For overexpression cell lines, we used the same method to establish the NCI-H2170-CKS2 cell lines. Cell Count Kit-8 assay and colony formation assay were used to determine cell viability and cell growth, respectively. Propidium iodide staining was used to determine cell cycle progression. The mRNA expression of CKS2 and protein expression of CKS2, p21, p53, and PTEN were determined by RT-qPCR and Western blotting, respectively. The expression of CKS2, p53, and Ki67 in tissues was determined by immunohistochemical stain. The in vivo tumorigenesis assays were used to determine the ability of CKS2 in tumor growth.

RESULTS

The results of RT-qPCR and Western blotting assay revealed that CKS2 upregulated expression in NSCLC tissues and cells. The results of the CCK-8 assay revealed that the shRNA group exhibited significantly lower cell viability and foci formation than the empty plasmid group, while CKS2 overexpression induces cell growth and cell cycle progression. The result of nude mice suggested that CKS2 knockdown expression suppressed tumorigenesis in the in vivo animal model.

CONCLUSIONS

Our study suggests that CKS2 could be a biomarker in the progression and prognosis of NSCLC.

G6PD inhibits ferroptosis in hepatocellular carcinoma by targeting cytochrome P450 oxidoreductase

Ferroptosis is an important cell necrosis and has been a focus in cancer related research.Increcsing studies have focused on the phenotype and function of ferroptosis in tumorigenesis, but the underlying mechanism remains poorly understood. Here, we used bioinformatics approaches to identify differentially expressed genes associated with HCC and ferroptosis. We found that G6PD (glucose-6-phosphate dehydrogenase) was highly expressed in HCC and was associated with poor prognosis. G6PD promoted the proliferation, migration and invasion, as well as inhibited ferroptosis in HCC cells. Pathway and functional enrichment analyses revealed that G6PD was related to the P450 metabolic pathway. POR (cytochrome P450 oxidoreductase) was downregulated in HCC and was significantly correlated with the prognosis. G6PD inhibited ferroptosis inin HCC cells through POR. Knockdown of G6PD reduced the tumor volume and tumor weight in vivo. Our study demonstrated that G6PD deficiency suppresses cell growth, metastasis, and tumorigenesis via upregulating POR, suggesting that G6PD may be used as a biomarker for the treatment of HCC in the future.

CXCL8 Facilitates the Survival and Paclitaxel-Resistance of Triple-Negative Breast Cancers

BACKGROUND

This study aimed to demonstrate CXCL8 expression in TNBC tissues and cells, and elucidate the functional mechanism of CXCL8 in paclitaxel (PTX)-resistant TNBC.

METHODS

Bioinformatics analysis was performed to identify differentially expressed genes (DEGs) in PTX-resistant TNBC using publicly available data from the GEO, TCGA and METABRIC databases. STRING was used to identify the interacting partners of CXCL8. Kaplan-Meier software was used to analyze the relationship between CXCL8 expression and patient survival rate. The protein expression and distribution of CXCL8 were examined by immunohistochemistry, MTT assay and colony formation assay were performed to determine cell viability of TNBC cells treated with PTX. Western blotting was used to assess the levels of drug resistance and apoptosis-related proteins. GO-KEGG analysis was conducted on the DEGs to identify enriched signaling pathways.

RESULTS

The results of bioinformatics analysis demonstrated a high expression of CXCL8 in TNBC tissues and cells. Kaplan-Meier analysis revealed that the expression of CXCL8 is associated with poor prognosis. CXCL8 was upregulated in PTX-resistant TNBC cells. Knockdown of CXCL8 increased the sensitivity of TNBC cells to PTX. Mechanically, CXCL8 deficiency regulated PTX resistance in TNBC cells via cell apoptosis signaling pathway.

CONCLUSION

Our work demonstrated that CXCL8 may be a potential molecule to be targeted for the treatment of PTX-resistant TNBC.

Ubiquitin-Specific Protease 29 Regulates Cdc25A-Mediated Tumorigenesis

Cell division cycle 25A (Cdc25A) is a dual-specificity phosphatase that is overexpressed in several cancer cells and promotes tumorigenesis. In normal cells, Cdc25A expression is regulated tightly, but the changes in expression patterns in cancer cells that lead to tumorigenesis are unknown. In this study, we showed that ubiquitin-specific protease 29 (USP29) stabilized Cdc25A protein expression in cancer cell lines by protecting it from ubiquitin-mediated proteasomal degradation. The presence of USP29 effectively blocked polyubiquitination of Cdc25A and extended its half-life. CRISPR-Cas9-mediated knockdown of USP29 in HeLa cells resulted in cell cycle arrest at the G0/G1 phase. We also showed that USP29 knockdown hampered Cdc25A-mediated cell proliferation, migration, and invasion of cancer cells in vitro. Moreover, NSG nude mice transplanted with USP29-depleted cells significantly reduced the size of the tumors, whereas the reconstitution of Cdc25A in USP29-depleted cells significantly increased the tumor size. Altogether, our results implied that USP29 promoted cell cycle progression and oncogenic transformation by regulating protein turnover of Cdc25A.

The Involvement of Ubiquitination Machinery in Cell Cycle Regulation and Cancer Progression

The cell cycle is a collection of events by which cellular components such as genetic materials and cytoplasmic components are accurately divided into two daughter cells. The cell cycle transition is primarily driven by the activation of cyclin-dependent kinases (CDKs), which activities are regulated by the ubiquitin-mediated proteolysis of key regulators such as cyclins, CDK inhibitors (CKIs), other kinases and phosphatases. Thus, the ubiquitin-proteasome system (UPS) plays a pivotal role in the regulation of the cell cycle progression via recognition, interaction, and ubiquitination or deubiquitination of key proteins. The illegitimate degradation of tumor suppressor or abnormally high accumulation of oncoproteins often results in deregulation of cell proliferation, genomic instability, and cancer occurrence. In this review, we demonstrate the diversity and complexity of the regulation of UPS machinery of the cell cycle. A profound understanding of the ubiquitination machinery will provide new insights into the regulation of the cell cycle transition, cancer treatment, and the development of anti-cancer drugs.

Autophagy Induction by Trichodermic Acid Attenuates Endoplasmic Reticulum Stress-Mediated Apoptosis in Colon Cancer Cells

Colorectal cancer (CRC) is the third leading malignant tumor in the world, which has high morbidity and mortality. In this study we found that trichodermic acid (TDA), a secondary metabolite isolated from the plant endophytic fungus Penicillium ochrochloronthe with a variety of biological and pharmacological activities, exhibited the antitumor effects on colorectal cancer cells in vitro and in vivo. Our results showed that TDA inhibited the proliferation of colon cancer cells in a dose-dependent manner. TDA induces sustained endoplasmic reticulum stress, which triggers apoptosis through IRE1α/XBP1 and PERK/ATF4/CHOP pathways. In addition, we found that TDA mediated endoplasmic reticulum stress also induces autophagy as a protective mechanism. Moreover, combined treatment of TDA with autophagy inhibitors significantly enhanced its anticancer effect. In conclusion, our results indicated that TDA can induce ER stress and autophagy mediated apoptosis, suggesting that targeting ER stress and autophagy may be an effective strategy for the treatment of CRC.

RNA-Binding RING E3-Ligase DZIP3/hRUL138 Stabilizes Cyclin D1 to Drive Cell-Cycle and Cancer Progression

DZIP3/hRUL138 is a poorly characterized RNA-binding RING E3-ubiquitin ligase with functions in embryonic development. Here we demonstrate that DZIP3 is a crucial driver of cancer cell growth, migration, and invasion. In mice and zebrafish cancer models, DZIP3 promoted tumor growth and metastasis. In line with these results, DZIP3 was frequently overexpressed in several cancer types. Depletion of DZIP3 from cells resulted in reduced expression of Cyclin D1 and a subsequent G1 arrest and defect in cell growth. Mechanistically, DZIP3 utilized its two different domains to interact and stabilize Cyclin D1 both at mRNA and protein levels. Using an RNA-binding lysine-rich region, DZIP3 interacted with the AU-rich region in 3' untranslated region of Cyclin D1 mRNA and stabilized it. Using a RING E3-ligase domain, DZIP3 interacted and increased K63-linked ubiquitination of Cyclin D1 protein to stabilize it. Remarkably, DZIP3 interacted with, ubiquitinated, and stabilized Cyclin D1 predominantly in the G1 phase of the cell cycle, where it is needed for cell-cycle progression. In agreement with this, a strong positive correlation of mRNA expression between DZIP3 and Cyclin D1 in different cancer types was observed. Additionally, DZIP3 regulated several cell cycle proteins by modulating the Cyclin D1-E2F axes. Taken together, this study demonstrates for the first time that DZIP3 uses a unique two-pronged mechanism in its stabilization of Cyclin D1 to drive cell-cycle and cancer progression. SIGNIFICANCE: These findings show that DZIP3 is a novel driver of cell-cycle and cancer progression via its control of Cyclin D1 mRNA and protein stability in a cell-cycle phase-dependent manner. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/2/315/F1.large.jpg.

Molecular crosstalk between cancer and neurodegenerative diseases

The progression of cancers and neurodegenerative disorders is largely defined by a set of molecular determinants that are either complementarily deregulated, or share remarkably overlapping functional pathways. A large number of such molecules have been demonstrated to be involved in the progression of both diseases. In this review, we particularly discuss our current knowledge on p53, cyclin D, cyclin E, cyclin F, Pin1 and protein phosphatase 2A, and their implications in the shared or distinct pathways that lead to cancers or neurodegenerative diseases. In addition, we focus on the inter-dependent regulation of brain cancers and neurodegeneration, mediated by intercellular communication between tumor and neuronal cells in the brain through the extracellular microenvironment. Finally, we shed light on the therapeutic perspectives for the treatment of both cancer and neurodegenerative disorders.

Ubiquitination-mediated degradation of SIRT1 by SMURF2 suppresses CRC cell proliferation and tumorigenesis

The NAD-dependent deacetylase sirtuin 1 (SIRT1), a member of the mammalian sirtuin family, plays a pivotal role in deacetylating histone and nonhistone proteins. Recently, it has been reported that SIRT1 is upregulated in various kinds of tumors and is associated with cell growth and metastasis. However, the factors and molecular mechanism regulating its cellular levels remain to be clarified. Here, we reported that the E3 ubiquitin ligase SMURF2 interacts with SIRT1 and mediates its ubiquitination and degradation. Depletion of SMURF2 leads to SIRT1 upregulation and induces the tumor formation and growth of colorectal cancer in vitro and in vivo. Furthermore, we show a negative correlation between SIRT1 and SMURF2 expression in human colorectal cancer. Thus, we propose a novel mechanism of colorectal tumorigenesis via SIRT1 regulation by SMURF2, which could potentially give rise to a new strategy for the treatment of colorectal cancer.

Cathepsin K inhibition-induced mitochondrial ROS enhances sensitivity of cancer cells to anti-cancer drugs through USP27x-mediated Bim protein stabilization

Cathepsin K (Cat K) is expressed in cancer cells, but the effect of Cat K on apoptosis is still elusive. Here, we showed that inhibition of Cat K sensitized the human carcinoma cells to anti-cancer drug through up-regulation of Bim. Inhibition of Cat K increased USP27x expression, and knock down of USP27x markedly blocked Cat K-induced up-regulation of Bim expression. Furthermore, inhibition of Cat K induced proteasome-dependent degradation of regulatory associated protein of mammalian target of rapamycin (Raptor). Down-regulation of Raptor expression increased mitochondrial ROS production, and mitochondria specific superoxide scavengers prevented USP27x-mediated stabilization of Bim by inhibition of Cat K. Moreover, combined treatment with Cat K inhibitor (odanacatib) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) reduced tumor growth and induced cell death in a xenograft model. Our results demonstrate that Cat K inhibition enhances anti-cancer drug sensitivity through USP27x-mediated the up-regulation of Bim via the down-regulation of Raptor.

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Inhibition of Cat K sensitizes cancer cells to anti-cancer drugs.

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Reduction of Raptor by inhibition of Cat K induces mitochondria dysfunction.

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Mitochondrial ROS induction by inhibition of Cat K induces USP27X expression.

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Up-regulation of USP27X by inhibition of Cat K stabilizes Bim protein.

Exosome circRNA secreted from adipocytes promotes the growth of hepatocellular carcinoma by targeting deubiquitination-related USP7

Hepatocellular carcinoma (HCC), the major form of liver cancer, has shown increasing incidence and poor prognosis. Adipose tissue is known to function in energy storage and metabolism regulation by the secretion of adipokines. Circular RNAs (circRNAs), a novel type of noncoding RNA, have recently been recognized as key factors in tumor development, but the role of exosome circRNAs derived from adipose tissues has not been defined yet. Here, adipose-secreted circRNAs were found to regulate deubiquitination in HCC, thus facilitating cell growth. It was observed that exosome circ-deubiquitination (circ-DB) is upregulated in HCC patients with higher body fat ratios. Moreover, in vitro and in vivo studies showed that exo-circ-DB promotes HCC growth and reduces DNA damage via the suppression of miR-34a and the activation of deubiquitination-related USP7. Finally, the results showed that the effects of adipose exosomes on HCC cells can be reversed by knockdown of circ-DB. These results indicate that exosome circRNAs secreted from adipocytes promote tumor growth and reduce DNA damage by suppressing miR-34a and activating the USP7/Cyclin A2 signaling pathway.

Control of DNA Replication Initiation by Ubiquitin

Eukaryotic cells divide by accomplishing a program of events in which the replication of the genome is a fundamental part. To ensure all cells have an accurate copy of the genome, DNA replication occurs only once per cell cycle and is controlled by numerous pathways. A key step in this process is the initiation of DNA replication in which certain regions of DNA are marked as competent to replicate. Moreover, initiation of DNA replication needs to be coordinated with other cell cycle processes. At the molecular level, initiation of DNA replication relies, among other mechanisms, upon post-translational modifications, including the conjugation and hydrolysis of ubiquitin. An example is the precise control of the levels of the DNA replication initiation protein Cdt1 and its inhibitor Geminin by ubiquitin-mediated proteasomal degradation. This control ensures that DNA replication occurs with the right timing during the cell cycle, thereby avoiding re-replication events. Here, we review the events that involve ubiquitin signalling during DNA replication initiation, and how they are linked to human disease.