Inhibition of USP7 induces p53-independent tumor growth suppression in triple-negative breast cancers by destabilizing FOXM1

Helicobacter pylori activates DOPEY1 to promote p53 degradation through the USP7/TRIP12 axis in gastric tumorigenesis

DOP1 leucine zipper-like protein A (DOPEY1), a member of the DOPEY family, is mainly localized in the Golgi apparatus, endosomes, and cytoplasmic compartments within cells. The involvement of DOPEY1 in H. pylori infection-induced carcinogenesis has remained unresolved. Here, we report that DOPEY1 is upregulated in GC tissues compared to adjacent normal tissues, correlating with poor prognosis. Mechanistically, H. pylori infection increases DOPEY1 expression and promotes p53 degradation through a CagA-dependent pathway. Using the String database and liquid chromatography-mass spectrometry, we identified DOPEY1-interacting proteins, confirming through co-immunoprecipitation that DOPEY1 interacts with USP7 and TRIP12. H. pylori infection enhances the expression of DOPEY1, USP7, and TRIP12, leading to p53 degradation, which is reversed by DOPEY1 silencing. Moreover, USP7 overexpression rescues p53 degradation in DOPEY1-silenced cells. Functionally, DOPEY1 knockdown reduces GC cell proliferation and suppresses tumor growth in mouse models. Immunohistochemistry analysis further reveals a link between DOPEY1, USP7, and TRIP12 expression, H. pylori infection, and GC progression. These findings demonstrate that H. pylori-induced upregulation of DOPEY1 drives p53 degradation via the USP7/TRIP12 axis, contributing to gastric tumorigenesis, and highlight DOPEY1 as a potential therapeutic target for H. pylori-associated GC.

FOXM1 could serve as a bridge mediating prognosis and immunity for clear cell renal cell carcinoma via single-cell and bulk RNA-sequencing

BACKGROUND

In the development of several cancers, the Forkhead Box M1 (FOXM1) is crucial. The relationship between the immune system and FOXM1 in renal cell carcinoma (ccRCC), which has been verified by bulk RNA sequencing and scRNA sequencing, is the primary subject of this research.

METHOD

Publicly available data related to FOXM1 and ccRCC were extracted from The Cancer Genome Atlas (TCGA) database. The impact of FOXM1 on the prognosis of ccRCC was examined using Cox regression analysis. Results were verified by immunohistochemistry and quantitative real-time PCR (qRT-PCR). Additionally, single-cell sequencing data were analyzed.

RESULTS

When compared to para-carcinoma tissues, the expression of FOXM1 was considerably higher in ccRCC tissues. Patients with elevated FOXM1 expression had lower survival rates. FOXM1 may be a standalone prognostic factor for ccRCC, according to results of univariate and multivariate Cox regression studies. Reduced FOXM1 expression was linked to higher immunotherapy sensitivity, according to immunocorrelation analysis. This suggests FOXM1 may mediate immunotherapy resistance in ccRCC. Additionally, FOXM1 showed strong associations with tumor mutation load, microsatellite instability, and antitumor immunity. These results imply FOXM1 may regulate antitumor immunity in the ccRCC microenvironment. Consistent results from immunohistochemistry, PCR, and single-cell RNA sequencing confirmed upregulated FOXM1 expression in ccRCC.

CONCLUSIONS

According to the findings, FOXM1 might be used as a stand-alone prognostic biomarker for ccRCC. Moreover, FOXM1 has exhibited robust correlations with microsatellite instability, tumor mutation burden, immune response, and immunotherapy efficacy. FOXM1 may promote ccRCC pathogenesis partly by suppressing antitumor immunity and mediating immunotherapy resistance.

TOR1 AIP1 interacts with p53 to enhance cell cycle dysregulation in prostate cancer progression

The cell cycle mechanism is an integration point where information is sent through an upstream signaling network, making it a potential target for cancer diagnosis and treatment. The LAP1 protein, encoded by the Tor1aip1 gene, is required to maintain the shape of the nuclear envelope and the progression of the cell cycle. The aim of this study was to determine the role of Tor1aip1 gene in PRAD development and its mechanism. We analyzed the expression and survival data of TOR1 AIP1 in PRAD patients in the TCGA database and verified the low expression of TOR1 AIP1 in prostate cancer by qPCR, western blot and immunohistology, which was correlated with the tumor stage and survival prognosis of PRAD. In addition, lentiviral vectors were used to mediate the up-regulation or down-regulation of TOR1 AIP1 expression in prostate cancer cells, and the effects of TOR1 AIP1 on tumor proliferation and related signaling pathways were investigated by cell counting kit- 8, colony formation assay, transwell assay, western blot, and flow cytometry. As a result, we found that TOR1 AIP1 enhances protein stability of p53 by directly interacting with p53, consequently inhibited tumor proliferation and invasion by inducing the cell cycle to be arrested in the S phase. Therefore, TOR1 AIP1 represents a promising therapeutic target in PRAD due to its ability to stabilize p53 and enhance its tumor-suppressive functions. Future studies should focus on elucidating its mechanisms, developing targeted therapies, and exploring its clinical potential in combination with existing treatments. By advancing our understanding of TOR1 AIP1, we may unlock new strategies for improving outcomes in PRAD patients.

USP13: A therapeutic target for combating tumorigenesis and antitumor therapy resistance

Ubiquitin-specific peptidase 13 (USP13) has emerged as a key regulator of proteins critical to the hallmarks of cancer, playing an essential role in cellular regulation. This deubiquitinating enzyme, often overexpressed in malignancies, wields its molecular scissors precisely, snipping ubiquitin tags to rescue oncoproteins from degradation. Our review highlights the dual role of USP13 in cancer biology: while it predominantly fuels tumor growth and metastasis, USP13 occasionally functions as a tumor suppressor. USP13 is as a formidable factor in cancer therapy, fortifying tumors against an arsenal of treatments. It bolsters DNA repair mechanisms, ignites prosurvival autophagy, and even reprograms cell lineages to evade targeted therapies. However, USP13 is also a promising target in the treatment of cancer. We highlight burgeoning strategies to neutralize USP13, from small molecule inhibitors to innovative protein degraders, which may disarm cancer resistance mechanisms. We also offer suggestions for future USP13 research, emphasizing the need for structural insights and more potent inhibitors. This review highlights the critical role of USP13 in cancer and underscores its potential as a therapeutic target for advancing cancer treatment.

Mouse mesenchymal stem cell-derived exosomal miR-205-5p modulates LPS-induced macrophage polarization and alleviates lung injury by regulating the USP7/FOXM1 axis

Exosomal microRNAs produced from mesenchymal stem cells (MSCs) are crucial in the management of acute lung injury (ALI). In this work, mMSCs separated from bone marrow were used to extract exosomes (MSC-Exos). MSC-Exos treatment attenuated pathological changes and scores, and edema in ALI mice. Also, MSC-Exos administration modulated the concentrations of inflammatory factors as well as the macrophage polarization both in vivo and in vitro. Upregulation of miR-205-5p in MSC-Exos regulated the macrophage polarization and the contents of inflammatory factors in animal and cell models. MiR-205-5p targeted USP7, and negatively modulated the expression of USP7. USP7 interacted with FOXM1, and reduced the ubiquitination degradation of FOXM1. MSC-derived exosomal miR-205-5p modulated ubiquitination of FOXM1 by targeting USP7. The ameliorative effect of MSC-Exos on the macrophage polarization and the inflammatory factors release was reversed with the overexpression of USP7 in animal and cell models. Collectively, MSC-derived exosomal miR-205-5p regulated lipopolysaccharide (LPS)-induced macrophage polarization and alleviated lung injury by the USP7/FOXM1 axis, which developed a potential target for the treatment of ALI.

USP7 facilitates deubiquitination of LRRC42 in colorectal cancer to accelerate tumorigenesis and augment Wnt/β-catenin signaling

Colorectal cancer is a prevalent malignancy with an increasing incidence worldwide. Leucine-rich repeat-containing protein 42 (LRRC42) is known to be dysregulated in tumor tissues, yet its role in colorectal cancer remains largely unexplored. Herein, the function of LRRC42 in colorectal cancer was investigated using clinical samples, cellular experiments, animal models, and multiple omics techniques. The results demonstrated that LRRC42 was highly expressed in colorectal cancer tissues and was associated with poor clinical outcomes. Silencing LRRC42 suppressed cell proliferation, induced G0/G1 phase arrest, and promoted apoptosis by reducing Bcl2 expression while elevating the expression of Bax, cleaved PARP and cleaved caspase 3. Conversely, LRRC42 overexpression exhibited the opposite effects. Consistent findings were observed in vivo. Additionally, ubiquitin specific peptidase 7 was identified as a potential LRRC42-interacting protein through immunoprecipitation-mass spectrometry, with ubiquitin specific peptidase 7 stabilizing LRRC42 expression by promoting its deubiquitination. Notably, LRRC42 overexpression partially reversed the effects of ubiquitin specific peptidase 7 silencing on tumor cell proliferation and apoptosis. mRNA sequencing analysis revealed that differentially expressed genes in LRRC42 overexpressing cells were linked to Wnt signaling pathway, suggesting that LRRC42 overexpression may activate this pathway. Furthermore, LRRC42 was proved to elevate the levels of ki67, cyclin D1 and WNT3, while reducing the level of p-β-catenin. These findings suggest that LRRC42 perhaps serve as a potential oncogenic factor in colorectal cancer, regulated by ubiquitin specific peptidase 7 and capable of activating Wnt/β-catenin signaling pathway.

Unveiling the molecular profile of a prostate carcinoma: implications for personalized medicine

BACKGROUND

Prostate cancer is the most common diagnosed tumor and the fifth cancer related death among men in Europe. Although several genetic alterations such as ERG-TMPRSS2 fusion, MYC amplification, PTEN deletion and mutations in p53 and BRCA2 genes play a key role in the pathogenesis of prostate cancer, specific gene alteration signature that could distinguish indolent from aggressive prostate cancer or may aid in patient stratification for prognosis and/or clinical management of patients with prostate cancer is still missing. Therefore, here, by a multi-omics approach we describe a prostate cancer carrying the fusion of TMPRSS2 with ERG gene and deletion of 16q chromosome arm.

RESULTS

We have observed deletion of KDM6A gene, which may represent an additional genomic alteration to be considered for patient stratification. The cancer hallmarks gene signatures highlight intriguing molecular aspects that characterize the biology of this tumor by both a high hypoxia and immune infiltration scores. Moreover, our analysis showed a slight increase in the Tumoral Mutational Burden, as well as an over-expression of the immune checkpoints. The omics profiling integrating hypoxia, ROS and the anti-cancer immune response, optimizes therapeutic strategies and advances personalized care for prostate cancer patients.

CONCLUSION

The here data reported can lay the foundation for predicting a poor prognosis for the studied prostate cancer, as well as the possibility of targeted therapies based on the modulation of hypoxia, ROS, and the anti-cancer immune response.

Ubiquitin-specific protease 7 maintains c-Myc stability to support pancreatic cancer glycolysis and tumor growth

BACKGROUND

The typical pathological feature of pancreatic ductal adenocarcinoma (PDAC) is a significant increase in stromal reaction, leading to a hypoxic and poorly vascularized tumor microenvironment. Tumor cells undergo metabolic reprogramming, such as the Warburg effect, yet the underlying mechanisms are not fully understood.

METHODS

Interference and overexpression experiments were conducted to analyze the in vivo and in vitro effects of USP7 on the growth and glycolysis of tumor cells. Small-molecule inhibitors of USP7 and transgenic mouse models of PDAC were employed to assess the consequences of targeting USP7 in PDAC. The molecular mechanism underlying USP7-induced c-Myc stabilization was determined by RNA sequencing, co-IP and western blot analyses.

RESULTS

USP7 is abnormally overexpressed in PDAC and predicts a poor prognosis. Hypoxia and extracellular matrix stiffness can induce USP7 expression in PDAC cells. Genetic silencing of USP7 inhibits the glycolytic phenotypes in PDAC cells, while its overexpression has the opposite effect, as demonstrated by glucose uptake, lactate production, and extracellular acidification rate. Importantly, USP7 promotes PDAC tumor growth in a glycolysis-dependent manner. The small-molecule inhibitor P5091 targeting USP7 effectively suppresses the Warburg effect and cell growth in PDAC. In a transgenic mouse model of PDAC, named KPC, P5091 effectively blocks tumor progression. Mechanistically, USP7 interacts with c-Myc, enhancing its stability and expression, which in turn upregulates expression of glycolysis-related genes.

CONCLUSIONS

This study sheds light on the molecular mechanisms underlying the Warburg effect in PDAC and unveils USP7 as a potential therapeutic target for improving PDAC treatment.

Latest Therapeutical Approaches for Triple-Negative Breast Cancer: From Preclinical to Clinical Research

Triple-negative breast cancer (TNBC) represents roughly one-sixth of all breast cancer patients, but accounts for 30-40% of breast cancer deaths. Due to the lack of typical biomarkers exploited clinically for breast cancer, it remains very difficult to treat. Moreover, its intrinsic high heterogeneity and proneness to become resistant to the drugs administered makes the treatment management very challenging for oncologists. Herein, we outline the different therapies used currently for TNBC and list the ongoing clinical trials to provide an overview of the most recent TNBC therapeutic landscape. In addition, we highlight the emerging therapies in the preclinical stage that hold the most promise, such as epigenetic modulators, CRISPR, miniproteins, radioconjugates, cancer vaccines, and PROTACs. Moreover, we navigate through the existing limitations and challenges which hamper the development of new and more effective treatments for TNBC. Lastly, we point to emerging new directions that may revolutionize future therapy for TNBC.

M1 macrophage-derived exosomes alleviate leukemia by causing mitochondrial dysfunction

Acute myeloid leukemia (AML) is one type of blood cancer that initially has a high cure rate but frequently relapses and leading to death. Therefore, there is an urgent need for innovative AML treatments. The leukemia C1498 cells were co-cultured with M1 macrophage-derived exosomes (M1-exo), and the proliferation and apoptosis of C1498 cells were investigated using CCK-8 and flow cytometry, respectively. qPCR and Western blot were applied to determine the PGAM5 expression in M1-exo treated C1498 cells. The role of M1-exo-derived PGAM5 in mitochondria was examined via fluorescence staining. The anti-inflammatory effects of M1-exo-derived PGAM5 and M1-exo were evaluated by flow cytometry, HE staining, and immunohistochemistry in xenograft and nude mouse tumorigenic models. M1-exo exhibited a potent capability to attenuate C1498 cell proliferation, and induce cell apoptosis. In vivo experimentation demonstrated that administration of M1-exo led to a reduction in leukocyte count, alleviated inflammatory infiltration, decreased liver and spleen weights, and significantly diminished tumor size. PGAM5 was elevated in M1-exo, and knockdown of PGAM5 in C1498 cells and M1-exo enhanced proliferation and reduced apoptosis in C1498 cells. Concurrently, M1-exo-derived PGAM5 decreased mitochondrial membrane potential and increased calcium influx in vitro. In vivo, studies showed that knockdown of PGAM5 in M1-exo elevated liver and spleen weights, augmented tumor size, and intensified hepatic inflammatory infiltration. Our study reveals that M1-exo induces mitochondrial dysfunction against leukemia through PGAM5.

SNRPB2 promotes triple-negative breast cancer progression by controlling alternative splicing of MDM4 pre-mRNA

Alternative splicing generates cancer-specific transcripts and is now recognized as a hallmark of cancer. However, the critical oncogenic spliceosome-related proteins involved in triple-negative breast cancer (TNBC) remain elusive. Here, we explored the expression pattern of spliceosome-related proteins in TNBC, non-TNBC, and normal breast tissues from The Cancer Genome Atlas breast cancer (TCGA-BRCA) cohort, revealing higher expression of nearly half of spliceosome-related proteins in TNBC than their counterparts. Among these TNBC-specific spliceosome-related proteins, the expression of SNRPB2 was associated with poor prognosis in patients with TNBC. In TNBC cells, the knockdown of SNRPB2 strongly suppressed cell proliferation and invasion and induced cell cycle arrest. Mechanistically, transcriptome data showed that SNRPB2 knockdown inactivated E2F1 signaling, which regulated the cell cycle. We further validated the downregulation of several cell cycle genes in SNRPB2 knockdown cells. Moreover, the analysis showed that SNRPB2 knockdown triggered the alteration of many alternative splicing events, most of which were skipping of exon. In TNBC cells, it was found that SNRPB2 knockdown led to the skipping of exon 6 in MDM4 pre-mRNA, generating MDM4-S transcript and downregulating MDM4 protein expression. More importantly, downregulation of MDM4 decreased retinoblastoma 1 (Rb1) protein expression, which is a target of MDM4 and a regulator of E2F1 signaling. In summary, the current study revealed an SNRPB2/MDM4/Rb axis in promoting the progression of TNBC, providing novel insights and novel targets for combating TNBC.

The Role and Mechanism of Deubiquitinase USP7 in Tumor-Associated Inflammation

Deubiquitinating enzymes are a class of proteases that remove ubiquitin tags from proteins, thereby controlling protein stability and function. Tumor inflammation arises from interactions between tumor cells and their microenvironment, which trigger an inflammatory response. The deubiquitinating enzyme USP7 plays a central role in this process. Research suggests that USP7 may modulate various signaling pathways related to inflammatory responses through its deubiquitinating activity, thereby influencing tumor development and progression, including regulating T cell immune activity, improving macrophage anti-tumor activity, and regulating NF-κB signal pathways. Overall, describing the role and mechanism of USP7 in the tumor inflammatory response is of great importance for elucidating the regulatory mechanism of tumor inflammation and developing new therapeutic strategies. This article mainly reviews the structure, function, role, and mechanism of USP7 in the tumor inflammation response.

Therapeutic Landscape of FOXM1 in Triple-Negative Breast Cancer and Aggressive Solid Cancers

Triple-negative breast cancer (TNBC) is one of the most aggressive forms of breast cancer, lacking common treatment targets such as estrogen (ER), progesterone (PR), and HER2 receptors. This subtype is associated with significant heterogeneity, chemoresistance, early recurrence, metastasis, and poor patient survival. FOXM1 is a cancer-promoting transcription factor that plays a critical role in TNBC and other highly aggressive cancers by driving cell proliferation, invasion, metastasis, and drug resistance. In TNBC, mutations in the TP53 gene-detected in approximately 80% of patients-lead to the overexpression of FOXM1, making it a promising therapeutic target. Beyond TNBC, FOXM1 is implicated in other solid cancers, such as brain (glioblastoma), lung, and pancreatic cancers, and is considered an Achilles' heel of aggressive cancers. Despite its potential as a therapeutic target, there are currently no FDA-approved FOXM1 inhibitors, and none have advanced to clinical trials. This review explores the role of FOXM1 in cancer progression and highlights the current status of efforts to develop effective FOXM1 inhibitors.

Tetrahydrocurcumin targets TRIP13 inhibiting the interaction of TRIP13/USP7/c-FLIP to mediate c-FLIP ubiquitination in triple-negative breast cancer

INTRODUCTION

Triple-negative breast cancer (TNBC) has a high mortality rate and limited treatment options. Tetrahydrocurcumin (THC), a major metabolite of curcumin, has potential antitumor activities. However, the antitumor effects and mechanism of THC in TNBC remain elusive.

OBJECTIVES

To investigate the mechanism of THC in combating TNBC by targeting TRIP13 to disrupt the interaction of the TRIP13/USP7/c-FLIP complex and mediate c-FLIP ubiquitination both in vitro and in vivo.

METHODS

Apoptosis was measured by TUNEL and flow cytometry. Click chemistry-based target fishing, CETSA, DARTS, and SPR were used to identify direct target of THC. Protein interactions was examined using co-immunoprecipitation. The role of USP7 in THC-mediated c-FLIP ubiquitination was evaluated by in vitro deubiquitination assay. Human breast cancer clinical samples were employed to assess the expression of c-FLIP, TRIP13, and USP7. The impact of THC on USP7/TRIP13/c-FLIP was analyzed using co-immunoprecipitation, confocal microscopy, molecular docking and dynamics simulations.

RESULTS

THC effectively inhibits TNBC cell proliferation and tumor growth in vitro and in vivo without significant toxicity. Mechanistically, THC induces extrinsic apoptosis in TNBC primarily by promoting degradation of c-FLIP, a key negative regulator in the apoptotic pathway. Furthermore, utilizing click chemistry-based target fishing, we identified TRIP13, a component of the highly conserved AAA ATPase family, as a direct target of THC in combating TNBC. Interestingly, contrary to previous drug-target studies, the knockdown of TRIP13 further amplified the antitumor effects of THC. After in-depth investigation, it was revealed that TRIP13 forms a trimeric complex with USP7 and c-FLIP in TNBC cells. THC specifically targets TRIP13 to disrupt the interaction of TRIP13/USP7/c-FLIP, leading to the ubiquitination of c-FLIP, ultimately inducing extrinsic apoptosis.

CONCLUSIONS

These findings offer new insights into the novel molecular mechanisms of anti-TNBC effects of THC and present a promising targeted therapeutic strategy for TNBC.

PROTAC as a novel anti-cancer strategy by targeting aging-related signaling

Aging and cancer share common cellular hallmarks, including cellular senescence, genomic instability, and abnormal cell death and proliferation, highlighting potential areas for therapeutic interventions. Recent advancements in targeted protein degradation technologies, notably Proteolysis-Targeting Chimeras (PROTACs), offer a promising approach to address these shared pathways. PROTACs leverage the ubiquitin-proteasome system to specifically degrade pathogenic proteins involved in cancer and aging, thus offering potential solutions to key oncogenic drivers and aging-related cellular dysfunction. This abstract summarizes the recent progress of PROTACs in targeting critical proteins implicated in both cancer progression and aging, and explores future perspectives in integrating these technologies for more effective cancer treatments.

Immunosuppressive SOX9-AS1 Resists Triple-Negative Breast Cancer Senescence Via Regulating Wnt Signalling Pathway

Long noncoding RNAs (lncRNAs) are involved in the regulation of triple-negative breast cancer (TNBC) senescence, while pro-carcinogenic lncRNAs resist senescence onset leading to the failure of therapy-induced senescence (TIS) strategy, urgently identifying the key senescence-related lncRNAs (SRlncRNAs). We mined seven SRlncRNAs (SOX9-AS1, LINC01152, AC005152.3, RP11-161 M6.2, RP5-968 J1.1, RP11-351 J23.1 and RP11-666A20.3) by bioinformatics, of which SOX9-AS1 was reported to be pro-carcinogenic. In vitro experiments revealed the highest expression of SOX9-AS1 in MDA-MD-231 cells. SOX9-AS1 knockdown inhibited cell growth (proliferation, cycle and apoptosis) and malignant phenotypes (migration and invasion), while SOX9-AS1 overexpression rescued these effects. Additionally, SOX9-AS1 knockdown facilitated tamoxifen-induced cellular senescence and the transcription of senescence-associated secretory phenotype (SASP) factors (IL-1α, IL-1β, IL-6 and IL-8) mechanistically by resisting senescence-induced Wnt signal (GSK-3β/β-catenin) activation. Immune infiltration analysis revealed that low SOX9-AS1 expression was accompanied by a high infiltration of naïve B cells, CD8+ T cells and γδ T cells. In conclusion, SOX9-AS1 resists TNBC senescence via regulating the Wnt signalling pathway and inhibits immune infiltration. Targeted inhibition of SOX9-AS1 enhances SASP and thus mobilises immune infiltration to adjunct TIS strategy.

Targeting the p53-p21 axis in liver cancer: Linking cellular senescence to tumor suppression and progression

Liver cancer is a major health epidemic worldwide, mainly due to its high mortality rates and limited treatment options. The association of cellular senescence to tumorigenesis and the cancer hallmarks remains a subject of interest in cancer biology. The p53-p21 signalling axis is an important regulator in restoring the cell's balance by supporting tumor suppression and tumorigenesis in liver cancer. We review the novel molecular mechanisms that p53 and its downstream effector, p21, employ to induce cellular senescence, making it last longer, and halt the proliferation of damaged hepatocytes to become tumorous cells. We also examine how dysregulation of this pathway contributes to HCC pathogenesis, proliferation, survival, acquired resistance to apoptosis, and increased invasiveness. Furthermore, we comprehensively describe the molecular cross-talk between the p53-p21 signalling axis and major cell cycle signalling pathways, including Wnt/β-catenin, PI3K/Akt, and TGF-β in liver cancer and provide an overview of promising candidates for chemoprevention and future therapeutic strategies. This review article explores the roles of the p53-p21 pathway in liver cancer, examining its function in promoting cellular senescence under normal conditions and its potential role in cancer progression. It also highlights novel therapeutic drugs and drug targets within the pathway and discusses the implications for treatment strategies and prognosis in liver cancer.

USP33 facilitates the ovarian cancer progression via deubiquitinating and stabilizing CBX2

Post-translational modifications of proteins play a pivotal role in both the initiation and progression of ovarian cancer. Despite the recognition of USP33 as a significant factor in various cancers, its specific function and underlying mechanisms in ovarian cancer remain elusive. Proteomics and ubiquitinomics approaches were coupled to screen novel substrate proteins directly regulated by USP33. Our findings unveil that USP33 was observed to eliminate K27- and K48-linked ubiquitin chains from CBX2 at the K277 position. Notably, acetylation of CBX2 at K199, catalyzed by lysine acetyltransferase GCN5, was found to enhance its interaction with USP33, subsequently promoting further deubiquitination and stabilization. Functionally, our experiments demonstrate that USP33 significantly enhances ovarian cancer proliferation and metastasis in a CBX2-dependent manner. Furthermore, analysis revealed a direct positive correlation between the expression levels of USP33 and CBX2 proteins in human specimens, with elevated levels being associated with reduced survival rates in ovarian cancer patients. These findings elucidate the mechanism by which USP33 augments ovarian cancer progression through the stabilization of CBX2, underscoring the USP33-CBX2 axis as a promising therapeutic target in ovarian cancer management.

In vivo CRISPR screens identify Mga as an immunotherapy target in triple-negative breast cancer

Immune evasion is not only critical for tumor initiation and progression, but also determines the efficacy of immunotherapies. Through iterative in vivo CRISPR screens with seven syngeneic tumor models, we identified core and context-dependent immune evasion pathways across cancer types. This valuable high-confidence dataset is available for the further understanding of tumor intrinsic immunomodulators, which may lead to the discovery of effective anticancer therapeutic targets. With a focus on triple-negative breast cancer (TNBC), we found that Mga knock-out significantly enhances antitumor immunity and inhibits tumor growth. Transcriptomics and single-cell RNA sequencing analyses revealed that Mga influences various immune-related pathways in the tumor microenvironment. Our findings suggest that Mga may play a role in modulating the tumor immune landscape, though the precise mechanisms require further investigation. Interestingly, we observed that low MGA expression in breast cancer patients correlates with a favorable prognosis, particularly in those with active interferon-γ signaling. These observations provide insights into tumor immune escape mechanisms and suggest that further exploration of MGA's function could potentially lead to effective therapeutic strategies in TNBC.

The deubiquitinase Usp7 in Drosophila melanogaster is required for synaptonemal complex maintenance

Meiosis is a form of cell division that is essential to sexually reproducing organisms and is therefore highly regulated. Each event of meiosis must occur at the correct developmental stage to ensure that chromosomes are segregated properly during both meiotic divisions. One unique meiosis-specific structure that is tightly regulated in terms of timing of assembly and disassembly is the synaptonemal complex (SC). While the mechanism(s) for assembly and disassembly of the SC are poorly understood in Drosophila melanogaster, posttranslational modifications, including ubiquitination and phosphorylation, are known to play a role. Here, we identify a role for the deubiquitinase Usp7 in the maintenance of the SC in early prophase and show that its function in SC maintenance is independent of the meiotic recombination process. Using two usp7 shRNA constructs that result in different knockdown levels, we have shown that the presence of SC through early/mid-pachytene is critical for normal levels and placement of crossovers.

Down-regulation of microRNA-23a promotes pancreatic ductal adenocarcinoma initiation and progression by up-regulation of FOXM1 expression

Transcriptional factor Forkhead box M1 (FOXM1) plays an important role in pancreatic ductal adenocarcinoma (PDAC) development and progression. The molecular mechanisms underlying its dysregulation remain unclear. We identified and functionally validated the microRNAs (miRNAs) that critically regulate FOXM1 expression in PDAC. The expression levels of miRNA-23a (miR-23a-3p and -5p) were altered in PDAC cell lines and their effects on FOXM1 signaling and cell proliferation and migration and tumorigenesis were examined in vitro and in vivo using mouse PDAC models. Compared with non-tumor pancreatic tissues, PDAC tissues and cell lines exhibited significantly reduced levels of miR-23a expression. Reduced miR-23a expression and concomitant increase in FOXM1 expression were also observed in acinar-to-ductal metaplasia and pancreatic intraepithelial neoplasia, the major premalignant lesions of PDAC. Transgenic expression of miR-23a reduced the expression of FOXM1 and suppressed cell proliferation and migration in PDAC cells, whereas the inhibitors of miR-23a did the opposite. Loss or reduced levels of miR-23a increased the levels of FOXM1 expression, while increased expression of FOXM1 down-regulated miR-23a expression, suggesting that miR-23a and FOXM1 were mutual negative regulators of their expression in PDAC cells. Therefore, the miR-23a/FOXM1 signaling axis is important in PDAC initiation and progression and could serve as an interventional or therapeutic target for patients with early or late stages of PDAC.

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.

Discovery of a Highly Potent, Selective and Efficacious USP7 Degrader for the Treatment of Acute Lymphoblastic Leukemia

USP7 is an attractive therapeutic target for cancers, especially for acute lymphoblastic leukemia (ALL) with wild-type p53. Herein, we report the discovery of XM-U-14 as a highly potent, selective and efficacious USP7 proteolysis-targeting chimera degrader. XM-U-14 achieves DC50 values of 0.74 nM and Dmax of 93% in inducing USP7 degradation in RS4;11 cell lines, and also significantly inhibits ALL cell growth. XM-U-14 even at 5 mg/kg dosed daily effectively inhibits RS4;11 tumor growth with 64.7% tumor regressions and causes no signs of toxicity in mice. XM-U-14 is a promising USP7 degrader for further optimization for ALL treatment.

Ubiquitin recruiting chimera: more than just a PROTAC

Ubiquitinylation of protein substrates results in various but distinct biological consequences, among which ubiquitin-mediated degradation is most well studied for its therapeutic application. Accordingly, artificially targeted ubiquitin-dependent degradation of various proteins has evolved into the therapeutically relevant PROTAC technology. This tethered ubiquitinylation of various targets coupled with a broad assortment of modifying E3 ubiquitin ligases has been made possible by rational design of bi-specific chimeric molecules that bring these proteins in proximity. However, forced ubiquitinylation inflicted by the binary warheads of a chimeric PROTAC molecule should not necessarily result in protein degradation but can be used to modulate other cellular functions. In this respect it should be noted that the ubiquitinylation of a diverse set of proteins is known to control their transport, transcriptional activity, and protein-protein interactions. This review provides examples of potential PROTAC usage based on non-degradable ubiquitinylation.

USP7 as an emerging therapeutic target: A key regulator of protein homeostasis

Maintaining protein balance within a cell is essential for proper cellular function, and disruptions in the ubiquitin-proteasome pathway, which is responsible for degrading and recycling unnecessary or damaged proteins, can lead to various diseases. Deubiquitinating enzymes play a vital role in regulating protein homeostasis by removing ubiquitin chains from substrate proteins, thereby controlling important cellular processes, such as apoptosis and DNA repair. Among these enzymes, ubiquitin-specific protease 7 (USP7) is of particular interest. USP7 is a cysteine protease consisting of a TRAF region, catalytic region, and C-terminal ubiquitin-like (UBL) region, and it interacts with tumor suppressors, transcription factors, and other key proteins involved in cell cycle regulation and epigenetic control. Moreover, USP7 has been implicated in the pathogenesis and progression of various diseases, including cancer, inflammation, neurodegenerative conditions, and viral infections. Overall, characterizing the functions of USP7 is crucial for understanding the pathophysiology of diverse diseases and devising innovative therapeutic strategies. This article reviews the structure and function of USP7 and its complexes, its association with diseases, and its known inhibitors and thus represents a valuable resource for advancing USP7 inhibitor development and promoting potential future treatment options for a wide range of diseases.