Therapeutic inhibition of USP9x-mediated Notch signaling in triple-negative breast cancer

Genomic characterization reveals distinct mutational landscapes and therapeutic implications between different molecular subtypes of triple-negative breast cancer

Triple-negative breast cancer (TNBC) has high heterogeneity, poor prognosis, and limited treatment success. Recently, an immunohistochemistry-based surrogate classification for the "Fudan University Shanghai Cancer Center (FUSCC) subtyping" has been developed and is considered more suitable for clinical application. Seventy-one paraffin-embedded sections of surgically resected TNBC were classified into four molecular subtypes using the IHC-based surrogate classification. Genomic analysis was performed by targeted next-generation sequencing and the specificity of the subtypes was explored by bioinformatics, including survival analysis, multivariate Cox regression, pathway enrichment, Pyclone analysis, mutational signature analysis and PHIAL analysis. AKT1 and BRCA1 mutations were identified as independent prognostic factors in TNBC. TNBC molecular subtypes encompass distinct genomic landscapes that show specific heterogeneities. The luminal androgen receptor (LAR) subtype was associated with mutations in PIK3CA and PI3K pathways, which are potentially sensitive to PI3K pathway inhibitors. The basal-like immune-suppressed (BLIS) subtype was characterized by high genomic instability and the specific possession of signature 19 while patients in the immunomodulatory (IM) subtype belonged to the PD-L1 ≥ 1% subgroup with enrichment in Notch signaling, suggesting a possible benefit of immune checkpoint inhibitors and Notch inhibitors. Moreover, mesenchymal-like (MES) tumors displayed enrichment in the receptor tyrosine kinase (RTK)-RAS pathway and potential sensitivity to RTK pathway inhibitors. The findings suggest potential treatment targets and prognostic factors, indicating the possibility of TNBC stratified therapy in the future.

Cellular functions, molecular signalings and therapeutic applications: Translational potential of deubiquitylating enzyme USP9X as a drug target in cancer treatment

Protein ubiquitination, one of the most significant post-translational modifications, plays an important role in controlling the proteins activity in diverse cellular processes. The reversible process of protein ubiquitination, known as deubiquitination, has emerged as a critical mechanism for maintaining cellular homeostasis. The deubiquitinases (DUBs), which participate in deubiquitination process are increasingly recognized as potential candidates for drug discovery. Among these DUBs, ubiquitin-specific protease 9× (USP9X), a highly conserved member of the USP family, exhibits versatile functions in various cellular processes, including the regulation of cell cycle, protein endocytosis, apoptosis, cell polarity, immunological microenvironment, and stem cell characteristics. The dysregulation and abnormal activities of USP9X are influenced by intricate cellular signaling pathway crosstalk and upstream non-coding RNAs. The complex expression patterns and controversial clinical significance of USP9X in cancers suggest its potential as a prognostic biomarker. Furthermore, USP9X inhibitors has shown promising antitumor activity and holds the potential to overcome therapeutic resistance in preclinical models. However, a comprehensive summary of the role and molecular functions of USP9X in cancer progression is currently lacking. In this review, we provide a comprehensive delineation of USP9X participation in numerous critical cellular processes, complicated signaling pathways within the tumor microenvironment, and its potential translational applications to combat therapeutic resistance. By systematically summarizing the updated molecular mechanisms of USP9X in cancer biology, this review aims to contribute to the advancement of cancer therapeutics and provide essential insights for specialists and clinicians in the development of improved cancer treatment strategies.

Isoform alterations in the ubiquitination machinery impacting gastrointestinal malignancies

The advancement of RNAseq and isoform-specific expression platforms has led to the understanding that isoform changes can alter molecular signaling to promote tumorigenesis. An active area in cancer research is uncovering the roles of ubiquitination on spliceosome assembly contributing to transcript diversity and expression of alternative isoforms. However, the effects of isoform changes on functionality of ubiquitination machineries (E1, E2, E3, E4, and deubiquitinating (DUB) enzymes) influencing onco- and tumor suppressor protein stabilities is currently understudied. Characterizing these changes could be instrumental in improving cancer outcomes via the identification of novel biomarkers and targetable signaling pathways. In this review, we focus on highlighting reported examples of direct, protein-coded isoform variation of ubiquitination enzymes influencing cancer development and progression in gastrointestinal (GI) malignancies. We have used a semi-automated system for identifying relevant literature and applied established systems for isoform categorization and functional classification to help structure literature findings. The results are a comprehensive snapshot of known isoform changes that are significant to GI cancers, and a framework for readers to use to address isoform variation in their own research. One of the key findings is the potential influence that isoforms of the ubiquitination machinery have on oncoprotein stability.

Novel insights into Notch signaling in tumor immunity: potential targets for cancer immunotherapy

Notch signaling pathway is a highly conserved system of cell-to-cell communication that participates in various biological processes, such as stem cell maintenance, cell fate decision, cell proliferation and death during homeostasis and development. Dysregulation of Notch signaling has been associated with many aspects of cancer biology, such as maintenance of cancer stem-like cells (CSCs), cancer cell metabolism, angiogenesis and tumor immunity. Particularly, Notch signaling can regulate antitumor or pro-tumor immune cells within the tumor microenvironment (TME). Currently, Notch signaling has drawn significant attention in the therapeutic development of cancer treatment. In this review, we focus on the role of Notch signaling pathway in remodeling tumor immune microenvironment. We describe the impact of Notch signaling on the efficacy of cancer immunotherapies. Furthermore, we summarize the results of relevant preclinical and clinical trials of Notch-targeted therapeutics and discuss the challenges in their clinical application in cancer therapy. An improved understanding of the involvement of Notch signaling in tumor immunity will open the door to new options in cancer immunotherapy treatment.

A molecular approach to triple-negative breast cancer: targeting the Notch signaling pathway

INTRODUCTION

Triple-negative breast cancer is an aggressive subtype of breast cancer characterized by the absence of estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 expression. This phenotype renders triple-negative breast cancer cells refractory to conventional therapies, resulting in poor clinical outcomes and an urgent need for novel therapeutic approaches. Recent studies have implicated dysregulation of the Notch receptor signaling pathway in the development and progression of triple-negative breast cancer.

OBJECTIVE

This study aimed to conduct a comprehensive literature review to identify potential therapeutic targets of the Notch pathway. Our analysis focused on the upstream and downstream components of this pathway to identify potential therapeutic targets.

RESULTS

Modulating the Notch signaling pathway may represent a promising therapeutic strategy to treat triple-negative breast cancer. Several potential therapeutic targets within this pathway are in the early stages of development, including upstream (such as Notch ligands) and downstream (including specific molecules involved in triple-negative breast cancer growth). These targets represent potential avenues for therapeutic intervention in triple-negative breast cancer.

COMMENTS

Additional research specifically addressing issues related to toxicity and improving drug delivery methods is critical for the successful translation of these potential therapeutic targets into effective treatments for patients with triple-negative breast cancer.

Gene expression alterations predict the pathological complete response in triple-negative breast cancer exploratory analysis of the NACATRINE trial

This exploratory analysis of the Neoadjuvant Carboplatin in Triple Negative Breast Cancer (NACATRINE) study aimed to identify the biomarkers of pathological complete response (pCR) in patients with triple-negative breast cancer (TNBC) treated with neoadjuvant chemotherapy (NAC) within the context of a clinical trial. The NACATRINE trial is a phase II, single-center, randomized, open-label clinical trial that investigated the addition of carboplatin to sequential anthracycline- and taxane-based NAC for TNBC. We evaluated the gene expression in untreated samples to investigate its association with pCR, overall survival (OS), and disease-free survival (DFS). RNA was extracted from the tissue biopsy, and the nCounter Breast Cancer panel was used to analyze gene expression. Of the 66 patients included in the gene expression profiling analysis, 24 (36.4%) achieved pCR and 42 (63.6%) had residual disease. In unsupervised hierarchical clustering analyses, differentially expressed genes between patients with and without pCR were identified irrespective of the treatment (24 genes), carboplatin (37 genes), and non-carboplatin (27 genes) arms. In receiver operating characteristic (ROC) curve analysis, 10 genes in the carboplatin arm (area under the ROC curve [AUC], 0.936) and three genes in the non-carboplatin arm (AUC, 0.939) were considered to be potential pCR-associated biomarkers. We identified genes that were associated with improvements in OS and DFS in addition to being related to pCR. We successfully identified gene expression signatures associated with pCR in pretreatment samples of patients with TNBC treated with NAC. Further investigation of these biomarkers is warranted.

The deubiquitinase USP9X regulates RIT1 protein abundance and oncogenic phenotypes

RIT1 is a rare and understudied oncogene in lung cancer. Despite structural similarity to other RAS GTPase proteins such as KRAS, oncogenic RIT1 activity does not appear to be tightly regulated by nucleotide exchange or hydrolysis. Instead, there is a growing understanding that the protein abundance of RIT1 is important for its regulation and function. We previously identified the deubiquitinase USP9X as a RIT1 dependency in RIT1-mutant cells. Here, we demonstrate that both wild-type and mutant forms of RIT1 are substrates of USP9X. Depletion of USP9X leads to decreased RIT1 protein stability and abundance and resensitizes cells to EGFR tyrosine kinase inhibitors. Our work expands upon the current understanding of RIT1 protein regulation and presents USP9X as a key regulator of RIT1-driven oncogenic phenotypes.

Roles of USP9X in cellular functions and tumorigenesis (Review)

Ubiquitin-specific peptidase 9X (USP9X) is involved in certain human diseases, including malignancies, atherosclerosis and certain diseases of the nervous system. USP9X promotes the deubiquitination and stabilization of diverse substrates, thereby exerting a versatile range of effects on pathological and physiological processes. USP9X serves vital roles in the processes of cell survival, invasion and migration in various types of cancer. The present review aims to highlight the current knowledge of USP9X in terms of its structure and the possible mediatory mechanisms involved in certain types of cancer, providing a thorough introduction to its biological functions in carcinogenesis and further outlining its oncogenic or suppressive properties in a diverse range of cancer types. Finally, several perspectives regarding USP9X-targeted pharmacological therapeutics in cancer development are discussed.

Significance of NotchScore and JAG1 in predicting prognosis and immune response of low-grade glioma

Introduction

Low-grade glioma (LGG) is a prevalent malignant tumor in the intracranial region. Despite the advancements in treatment methods for this malignancy over the past decade, significant challenges still persist in the form of drug resistance and tumor recurrence. The Notch signaling pathway plays essential roles in many physiological processes as well as in cancer development. However, the significance of the pathway and family genes in LGG are poorly understood.

Methods

We conducted gene expression profiling analysis using the TCGA dataset to investigate the gene set associated with the Notch signaling pathway. we have proposed a metric called "NotchScore" that quantifies the strength of the Notch signaling pathway and enables us to assess its significance in predicting prognosis and immune response in LGG. We downregulated JAG1 in low-grade gliomas to assess its influence on the proliferation and migration of these tumors. Ultimately, we determined the impact of the transcription factor VDR on the transcription of PDL1 through chip-seq data analysis.

Results

Our findings indicate that tumors with a higher NotchScore, exhibit poorer prognosis, potentially due to their ability to evade the anti-tumor effects of immune cells by expressing immune checkpoints. Among the genes involved in the Notch signaling pathway, JAG1 has emerged as the most representative in terms of capturing the characteristics of both NotchScore and Notch pathways. The experimental results demonstrate that silencing JAG1 yielded a significant decrease in tumor cell proliferation in LGG cell lines. Our study revealed mechanisms by which tumors evade the immune system through the modulation of PDL1 transcription levels via the PI3K-Akt signaling pathway. Additionally, JAG1 potentially influences PDL1 in LGG by regulating the PI3K-Akt signaling pathway and the expression of the transcription factor VDR.

Discussion

These findings contribute to our understanding of immune evasion by tumors in LGG. The insights gained from this research may have implications for the development of therapeutic interventions for LGG.

Sulindac sulfide as a non-immune suppressive γ-secretase modulator to target triple-negative breast cancer

Introduction

Triple-negative breast cancer (TNBC) comprises a heterogeneous group of clinically aggressive tumors with high risk of recurrence and metastasis. Current pharmacological treatment options remain largely limited to chemotherapy. Despite promising results, the efficacy of immunotherapy and chemo-immunotherapy in TNBC remains limited. There is strong evidence supporting the involvement of Notch signaling in TNBC progression. Expression of Notch1 and its ligand Jagged1 correlate with poor prognosis. Notch inhibitors, including g-secretase inhibitors (GSIs), are quite effective in preclinical models of TNBC. However, the success of GSIs in clinical trials has been limited by their intestinal toxicity and potential for adverse immunological effects, since Notch plays key roles in T-cell activation, including CD8 T-cells in tumors. Our overarching goal is to replace GSIs with agents that lack their systemic toxicity and ideally, do not affect tumor immunity. We identified sulindac sulfide (SS), the active metabolite of FDA-approved NSAID sulindac, as a potential candidate to replace GSIs.

Methods

We investigated the pharmacological and immunotherapeutic properties of SS in TNBC models in vitro, ex-vivo and in vivo.

Results

We confirmed that SS, a known γ-secretase modulator (GSM), inhibits Notch1 cleavage in TNBC cells. SS significantly inhibited mammosphere growth in all human and murine TNBC models tested. In a transplantable mouse TNBC tumor model (C0321), SS had remarkable single-agent anti-tumor activity and eliminated Notch1 protein expression in tumors. Importantly, SS did not inhibit Notch cleavage in T- cells, and the anti-tumor effects of SS were significantly enhanced when combined with a-PD1 immunotherapy in our TNBC organoids and in vivo.

Discussion

Our data support further investigation of SS for the treatment of TNBC, in conjunction with chemo- or -chemo-immunotherapy. Repurposing an FDA-approved, safe agent for the treatment of TNBC may be a cost-effective, rapidly deployable therapeutic option for a patient population in need of more effective therapies.

USP9X deubiquitinates and stabilizes CDC123 to promote breast carcinogenesis through regulating cell cycle

Cell division cycle 123 (CDC123) has been implicated in a variety of human diseases. However, it remains unclear whether CDC123 plays a role in tumorigenesis and how its abundance is regulated. In this study, we found that CDC123 was highly expressed in breast cancer cells, and its high expression was positively correlated with a poor prognosis. Knowndown of CDC123 impaired the proliferation of breast cancer cells. Mechanistically, we identified a deubiquitinase, ubiquitin-specific peptidase 9, X-linked (USP9X), that could physically interact with and deubiquitinate K48-linked ubiquitinated CDC123 at the K308 site. Therefore, the expression of CDC123 was positively correlated with USP9X in breast cancer cells. In addition, we found that deletion of either USP9X or CDC123 led to altered expression of cell cycle-related genes and resulted in the accumulation of cells population in the G0/G1 phase, thereby suppressing cell proliferation. Treatment with the deubiquitinase inhibitor of USP9X, WP1130 (Degrasyn, a small molecule compound that USP9X deubiquitinase inhibitor), also led to the accumulation of breast cancer cells in the G0/G1 phase, but this effect could be rescued by overexpression of CDC123. Furthermore, our study revealed that the USP9X/CDC123 axis promotes the occurrence and development of breast cancer through regulating the cell cycle, and suggests that it may be a potential target for breast cancer intervention. In conclusion, our study demonstrates that USP9X is a key regulator of CDC123, providing a novel pathway for the maintenance of CDC123 abundance in cells, and supports USP9X/CDC123 as a potential target for breast cancer intervention through regulating the cell cycle.

Targeting ubiquitin specific proteases (USPs) in cancer immunotherapy: from basic research to preclinical application

Tumors have evolved in various mechanisms to evade the immune system, hindering the antitumor immune response and facilitating tumor progression. Immunotherapy has become a potential treatment strategy specific to different cancer types by utilizing multifarious molecular mechanisms to enhance the immune response against tumors. Among these mechanisms, the ubiquitin-proteasome system (UPS) is a significant non-lysosomal pathway specific to protein degradation, regulated by deubiquitinating enzymes (DUBs) that counterbalance ubiquitin signaling. Ubiquitin-specific proteases (USPs), the largest DUB family with the strongest variety, play critical roles in modulating immune cell function, regulating immune response, and participating in antigen processing and presentation during tumor progression. According to recent studies, the expressions of some USP family members in tumor cells are involved in tumor immune escape and immune microenvironment. This review explores the potential of targeting USPs as a new approach for cancer immunotherapy, highlighting recent basic and preclinical studies investigating the applications of USP inhibitors. By providing insights into the structure and function of USPs in cancer immunity, this review aims at assisting in developing new therapeutic approaches for enhancing the immunotherapy efficacy.

The Efficacy of CB-103, a First-in-Class Transcriptional Notch Inhibitor, in Preclinical Models of Breast Cancer

BACKGROUND

The efficacy of CB-103 was evaluated in preclinical models of both ER+ and TNBC. Furthermore, the therapeutic efficacy of combining CB-103 with fulvestrant in ER+ BC and paclitaxel in TNBC was determined.

METHODS

CB-103 was screened in combination with a panel of anti-neoplastic drugs. We evaluated the anti-tumor activity of CB-103 with fulvestrant in ESR1-mutant (Y537S), endocrine-resistant BC xenografts. In the same model, we examined anti-CSC activity in mammosphere formation assays for CB-103 alone or in combination with fulvestrant or palbociclib. We also evaluated the effect of CB-103 plus paclitaxel on primary tumors and CSC in a GSI-resistant TNBC model HCC1187. Comparisons between groups were performed with a two-sided unpaired Students' t-test. A one-way or two-way ANOVA followed by Tukey's post-analysis was performed to analyze the in vivo efficacy study results.

THE RESULTS

CB-103 showed synergism with fulvestrant in ER+ cells and paclitaxel in TNBC cells. CB-103 combined with fulvestrant or paclitaxel potently inhibited mammosphere formation in both models. Combination of CB-103 and fulvestrant significantly reduced tumor volume in an ESR1-mutant, the endocrine-resistant BC model. In a GSI-resistant TNBC model, CB-103 plus paclitaxel significantly delayed tumor growth compared to paclitaxel alone.

CONCLUSION

our data indicate that CB-103 is an attractive candidate for clinical investigation in endocrine-resistant, recurrent breast cancers with biomarker-confirmed Notch activity in combination with SERDs and/or CDKis and in TNBCs with biomarker-confirmed Notch activity in combination with taxane-containing chemotherapy regimens.

The chemokine monocyte chemoattractant protein-1/CCL2 is a promoter of breast cancer metastasis

Breast cancer is the most prevalent cancer worldwide, and metastasis is the leading cause of death in cancer patients. Human monocyte chemoattractant protein-1 (MCP-1/CCL2) was isolated from the culture supernatants of not only mitogen-activated peripheral blood mononuclear leukocytes but also malignant glioma cells based on its in vitro chemotactic activity toward human monocytes. MCP-1 was subsequently found to be identical to a previously described tumor cell-derived chemotactic factor thought to be responsible for the accumulation of tumor-associated macrophages (TAMs), and it became a candidate target of clinical intervention; however, the role of TAMs in cancer development was still controversial at the time of the discovery of MCP-1. The in vivo role of MCP-1 in cancer progression was first evaluated by examining human cancer tissues, including breast cancers. Positive correlations between the level of MCP-1 production in tumors and the degree of TAM infiltration and cancer progression were established. The contribution of MCP-1 to the growth of primary tumors and metastasis to the lung, bone, and brain was examined in mouse breast cancer models. The results of these studies strongly suggested that MCP-1 is a promoter of breast cancer metastasis to the lung and brain but not bone. Potential mechanisms of MCP-1 production in the breast cancer microenvironment have also been reported. In the present manuscript, we review studies in which the role of MCP-1 in breast cancer development and progression and the mechanisms of its production were examined and attempt to draw a consensus and discuss the potential use of MCP-1 as a biomarker for diagnosis.

The Notch signaling pathway: a potential target for cancer immunotherapy

Dysregulation of the Notch signaling pathway, which is highly conserved across species, can drive aberrant epigenetic modification, transcription, and translation. Defective gene regulation caused by dysregulated Notch signaling often affects networks controlling oncogenesis and tumor progression. Meanwhile, Notch signaling can modulate immune cells involved in anti- or pro-tumor responses and tumor immunogenicity. A comprehensive understanding of these processes can help with designing new drugs that target Notch signaling, thereby enhancing the effects of cancer immunotherapy. Here, we provide an up-to-date and comprehensive overview of how Notch signaling intrinsically regulates immune cells and how alterations in Notch signaling in tumor cells or stromal cells extrinsically regulate immune responses in the tumor microenvironment (TME). We also discuss the potential role of Notch signaling in tumor immunity mediated by gut microbiota. Finally, we propose strategies for targeting Notch signaling in cancer immunotherapy. These include oncolytic virotherapy combined with inhibition of Notch signaling, nanoparticles (NPs) loaded with Notch signaling regulators to specifically target tumor-associated macrophages (TAMs) to repolarize their functions and remodel the TME, combining specific and efficient inhibitors or activators of Notch signaling with immune checkpoint blockers (ICBs) for synergistic anti-tumor therapy, and implementing a customized and effective synNotch circuit system to enhance safety of chimeric antigen receptor (CAR) immune cells. Collectively, this review aims to summarize how Notch signaling intrinsically and extrinsically shapes immune responses to improve immunotherapy.

Exploring immune interactions in triple negative breast cancer: IL-1β inhibition and its therapeutic potential

Triple negative breast cancer (TNBC) has poor prognosis when compared to other breast cancer subtypes. Despite pre-clinical data supporting an immune targeted approach for TNBCs, immunotherapy has failed to demonstrate the impressive responses seen in other solid tumor malignancies. Additional strategies to modify the tumor immune microenvironment and potentiate response to immunotherapy are needed. In this review, we summarise phase III data supporting the use of immunotherapy for TNBC. We discuss the role of IL-1β in tumorigenesis and summarize pre-clinical data supporting IL-1β inhibition as a potential therapeutic strategy in TNBC. Finally, we present current trials evaluating IL-1β in breast cancer and other solid tumor malignancies and discuss future studies that may provide a strong scientific rationale for the combination of IL-1β and immunotherapy in the neoadjuvant and metastatic setting for people with TNBC.

Targeting Notch-Driven Cytokine Secretion: Novel Therapies for Triple Negative Breast Cancer

Compared with other breast cancer subtypes, triple negative breast cancer (TNBC) is an aggressive malignancy with a high recurrence rate and reduced overall survival. Immune checkpoint inhibition (ICI) has shown modest results in this subgroup, highlighting the need for improved targeted therapeutic options. Notch is a defining feature of TNBC and drives the expression of interleukin-1 beta (IL1β) and C-C motif chemokine ligand 2 (CCL2). These cytokines are involved in the recruitment of tumor-associated macrophages (TAMs) to the tumor, resulting in immune evasion and tumor progression. Targeting Notch, IL1β or CCL2 may reduce TAM recruitment and resistance to ICI, illuminating the potential of combination immunotherapy in TNBC.

Notch signaling, hypoxia, and cancer

Notch signaling is involved in cell fate determination and deregulated in human solid tumors. Hypoxia is an important feature in many solid tumors, which activates hypoxia-induced factors (HIFs) and their downstream targets to promote tumorigenesis and cancer development. Recently, HIFs have been shown to trigger the Notch signaling pathway in a variety of organisms and tissues. In this review, we focus on the pro- and anti-tumorigenic functions of Notch signaling and discuss the crosstalk between Notch signaling and cellular hypoxic response in cancer pathogenesis, including epithelia-mesenchymal transition, angiogenesis, and the maintenance of cancer stem cells. The pharmacological strategies targeting Notch signaling and hypoxia in cancer are also discussed in this review.

EOAI, a ubiquitin-specific peptidase 5 inhibitor, prevents non-small cell lung cancer progression by inducing DNA damage

OBJECTIVE

Targeting deubiquitinases (DUBs) has emerged as a promising avenue for anticancer drug development. However, the effect and mechanism of pan-DUB inhibitor EOAI on non-small cell lung cancer (NSCLC) remains to be studied.

MATERIALS AND METHODS

The expression of ubiquitin-specific peptidase 5 (USP5) in NSCLC was evaluated by immunohistochemistry. The effect of the USP5 inhibitor, EOAI, on NSCLC cell growth and cell cycle was evaluated by CCK-8 and PI staining. Apoptosis was detected by Annexin V-FITC/PI double staining. Autophagy was examined by LC3 immunofluorescence. Comet assay and γ-H2AX immunofluorescence staining were used to detect DNA damage, and Western blotting was used to detect the expression of apoptosis, cycle, autophagy and DNA damage-related proteins. In vivo experiments demonstrated the effect of EOAI on NSCLC.

RESULTS

We also found that USP5 was significantly upregulated in NSCLC tissues in this study. In addition, we show that EOAI can cause DNA damage in NSCLC cells while modulating the transcriptional activity of P53, thereby inducing cell cycle arrest in NSCLC cells, autophagy and apoptosis. In vivo experiments have shown that EOAI can inhibit tumors and synergistically enhance the anti-tumor effect of cisplatin.

CONCLUSION

USP5-mediated epigenetic regulation of oncogenes promotes the occurrence of NSCLC, which provides ideas for developing potential targeted therapy.

The role of Hedgehog and Notch signaling pathway in cancer

Notch and Hedgehog signaling are involved in cancer biology and pathology, including the maintenance of tumor cell proliferation, cancer stem-like cells, and the tumor microenvironment. Given the complexity of Notch signaling in tumors, its role as both a tumor promoter and suppressor, and the crosstalk between pathways, the goal of developing clinically safe, effective, tumor-specific Notch-targeted drugs has remained intractable. Drugs developed against the Hedgehog signaling pathway have affirmed definitive therapeutic effects in basal cell carcinoma; however, in some contexts, the challenges of tumor resistance and recurrence leap to the forefront. The efficacy is very limited for other tumor types. In recent years, we have witnessed an exponential increase in the investigation and recognition of the critical roles of the Notch and Hedgehog signaling pathways in cancers, and the crosstalk between these pathways has vast space and value to explore. A series of clinical trials targeting signaling have been launched continually. In this review, we introduce current advances in the understanding of Notch and Hedgehog signaling and the crosstalk between pathways in specific tumor cell populations and microenvironments. Moreover, we also discuss the potential of targeting Notch and Hedgehog for cancer therapy, intending to promote the leap from bench to bedside.

The tumor microenvironment and triple-negative breast cancer aggressiveness: shedding light on mechanisms and targeting

INTRODUCTION

In contrast to other breast cancer subtypes, there are currently limited options of targeted therapies for triple-negative breast cancer (TNBC). Immense research has demonstrated that not only cancer cells but also stromal cells and immune cells in the tumor microenvironment (TME) play significant roles in the progression of TNBC. It is thus critical to understand the components of the TME of TNBC and the interactions between the various cell populations.

AREAS COVERED

The components of the TME of TNBC identified by single-cell technologies are reviewed. Furthermore, the molecular interactions between the cells and the potential therapeutic targets contributing to the progression of TNBC are discussed.

EXPERT OPINION

Single-cell omics studies have contributed to the classification of cells in the TME and the identification of important cell types involved in the progression and the treatment of the tumor. The interactions between cancer cells and stromal cells/immune cells in the TME have led to the discovery of potential therapeutic targets. Experimental data with spatial and temporal resolution will further boost the understanding of the TME of TNBC.

The Notch signaling pathway in skeletal muscle health and disease

The Notch signaling pathway is a key regulator of skeletal muscle development and regeneration. Over the past decade, the discoveries of three new muscle disease genes have added a new dimension to the relationship between the Notch signaling pathway and skeletal muscle: MEGF10, POGLUT1, and JAG2. We review the clinical syndromes associated with pathogenic variants in each of these genes, known molecular and cellular functions of their protein products with a particular focus on the Notch signaling pathway, and potential novel therapeutic targets that may emerge from further investigations of these diseases. The phenotypes associated with two of these genes, POGLUT1 and JAG2, clearly fall within the realm of muscular dystrophy, whereas the third, MEGF10, is associated with a congenital myopathy/muscular dystrophy overlap syndrome classically known as early-onset myopathy, areflexia, respiratory distress, and dysphagia. JAG2 is a canonical Notch ligand, POGLUT1 glycosylates the extracellular domain of Notch receptors, and MEGF10 interacts with the intracellular domain of NOTCH1. Additional genes and their encoded proteins relevant to muscle function and disease with links to the Notch signaling pathway include TRIM32, ATP2A1 (SERCA1), JAG1, PAX7, and NOTCH2NLC. There is enormous potential to identify convergent mechanisms of skeletal muscle disease and new therapeutic targets through further investigations of the Notch signaling pathway in the context of skeletal muscle development, maintenance, and disease.

The Notch Signaling Pathway Contributes to Angiogenesis and Tumor Immunity in Breast Cancer

Breast cancer in women is the first leading tumor in terms of incidence worldwide. Some subtypes of BC lack distinct molecular targets and exhibit therapeutic resistance; these patients have a poor prognosis. Thus, the search for new molecular targets is an ongoing challenge for BC therapy. The Notch signaling pathway is found in both vertebrates and invertebrates, and it is a highly conserved in the evolution of the species, controlling cellular fates such as death, proliferation, and differentiation. Numerous studies have shown that improper activation of Notch signaling may lead to excessive cell proliferation and cancer, with tumor-promoting and tumor-suppressive effects in various carcinomas. Thus, inhibitors of Notch signaling are actively being investigated for the treatment of various tumors. The role of Notch signaling in BC has been widely studied in recent years. There is a growing body of evidence suggesting that Notch signaling has a pro-oncogenic role in BC, and the tumor-promoting effect is largely a result of the diverse nature of tumor immunity. Immunological abnormality is also a factor involved in the pathogenesis of BC, suggesting that Notch signaling could be a target for BC immunotherapies. Furthermore, angiogenesis is essential for BC growth and metastasis, and the Notch signaling pathway has been implicated in angiogenesis, so studying the role of Notch signaling in BC angiogenesis will provide new prospects for the treatment of BC. We summarize the potential roles of the current Notch signaling pathway and its inhibitors in BC angiogenesis and the immune response in this review and describe the pharmacological targets of Notch signaling in BC, which may serve as a theoretical foundation for future research into exploring this pathway for novel BC therapies.

Chimeric Oncolytic Adenovirus Armed Chemokine Rantes for Treatment of Breast Cancer

The immunosuppressive state in the tumor microenvironment (TME) of breast cancer makes it difficult to treat with immunotherapy. Oncolytic viruses not only lyse tumor cells but also reshape the TME. Therefore, they can play a multi-mechanism synergistic effect with immunotherapy. In this study, an oncolytic adenovirus Ad5F11bSP-Rantes was constructed and used as a vector to express the chemokine Rantes. The objective of this study was to test the dual mechanisms of the oncolytic effect mediated by virus replication and the enhanced anticancer immune response mediated by Rantes chemotaxis of immune cells. It was found that Ad5F11bSP-Rantes has strong infectivity and effective killing activity against breast cancer cells. In the established triple negative breast cancer (TNBC) xenograft model in NCG mice whose immune system was humanized with human peripheral blood mononuclear cells (PBMCs), Ad5F11bSP-Rantes achieved 88.33% tumor inhibition rate. Rantes expression was high in mouse blood, a large number of CD3+ lymphocytes infiltrated in tumor tissues and E-cadherin was up-regulated in cancer cells, suggesting that Ad5F11bSP-Rantes altered the TME and induced a reversal of cancer cell epithelial-mesenchymal transition (EMT). In conclusion, oncolytic adenovirus can exert the oncolytic effect and the chemotactic effect of immune cells and realize the synergy of multiple anticancer effects. This strategy creates a candidate treatment for the optimization of breast cancer, especially TNBC, combination therapy.

Roles of Notch Signaling in the Tumor Microenvironment

The Notch signaling pathway is an architecturally simple signaling mechanism, well known for its role in cell fate regulation during organ development and in tissue homeostasis. In keeping with its importance for normal development, dysregulation of Notch signaling is increasingly associated with different types of tumors, and proteins in the Notch signaling pathway can act as oncogenes or tumor suppressors, depending on the cellular context and tumor type. In addition to a role as a driver of tumor initiation and progression in the tumor cells carrying oncogenic mutations, it is an emerging realization that Notch signaling also plays a role in non-mutated cells in the tumor microenvironment. In this review, we discuss how aberrant Notch signaling can affect three types of cells in the tumor stroma-cancer-associated fibroblasts, immune cells and vascular cells-and how this influences their interactions with the tumor cells. Insights into the roles of Notch in cells of the tumor environment and the impact on tumor-stroma interactions will lead to a deeper understanding of Notch signaling in cancer and inspire new strategies for Notch-based tumor therapy.

Emerging drug targets for triple-negative breast cancer: A guided tour of the preclinical landscape

INTRODUCTION

Triple-negative breast cancer (TNBC) is the most fatal molecular subtype of breast cancer because of its aggressiveness and resistance to chemotherapy. FDA-approved therapies for TNBC are limited to poly(ADP-ribose) polymerase inhibitors, immune checkpoint inhibitors, and trophoblast cell surface antigen 2-targeted antibody-drug conjugate. Therefore, developing a novel effective targeted therapy for TNBC is an urgent unmet need.

AREAS COVERED

In this narrative review, we discuss emerging targets for TNBC treatment discovered in early translational studies. We focus on cancer cell membrane molecules, hyperactive intracellular signaling pathways, and the tumor microenvironment (TME) based on their druggability, therapeutic potency, specificity to TNBC, and application in immunotherapy.

EXPERT OPINION

The significant challenges in the identification and validation of TNBC-associated targets are 1) application of appropriate genetic, molecular, and immunological approaches for modulating the target, 2) establishment of a proper mouse model that accurately represents the human immune TME, 3) TNBC molecular heterogeneity, and 4) failure translation of preclinical findings to clinical practice. To overcome those difficulties, future research needs to apply novel technology, such as single-cell RNA sequencing, thermostable group II intron reverse transcriptase sequencing, and humanized mouse models. Further, combination treatment targeting multiple pathways in both the TNBC tumor and its TME is essential for effective disease control.

On the Study of Deubiquitinases: Using the Right Tools for the Job

Deubiquitinases (DUBs) have been the subject of intense scrutiny in recent years. Many of their diverse enzymatic mechanisms are well characterized in vitro; however, our understanding of these enzymes at the cellular level lags due to the lack of quality tool reagents. DUBs play a role in seemingly every biological process and are central to many human pathologies, thus rendering them very desirable and challenging therapeutic targets. This review aims to provide researchers entering the field of ubiquitination with knowledge of the pharmacological modulators and tool molecules available to study DUBs. A focus is placed on small molecule inhibitors, ubiquitin variants (UbVs), and activity-based probes (ABPs). Leveraging these tools to uncover DUB biology at the cellular level is of particular importance and may lead to significant breakthroughs. Despite significant drug discovery efforts, only approximately 15 chemical probe-quality small molecule inhibitors have been reported, hitting just 6 of about 100 DUB targets. UbV technology is a promising approach to rapidly expand the library of known DUB inhibitors and may be used as a combinatorial platform for structure-guided drug design.