A phase I trial of the γ-secretase inhibitor MK-0752 in combination with gemcitabine in patients with pancreatic ductal adenocarcinoma

Immunosuppressive JAG2+ tumor-associated neutrophils hamper PD-1 blockade response in ovarian cancer by mediating the differentiation of effector regulatory T cells

BACKGROUND

Tumor-associated neutrophils (TANs) play a critical role in modulating immune responses and exhibit significant heterogeneity. Our previous study demonstrated that jagged canonical Notch ligand 2 (JAG2)+ TANs were associated with an immunosuppressive microenvironment in high-grade serous ovarian cancer (HGSOC), but the underlying mechanism remains unclear. This study aimed to elucidate the role of JAG2+ TANs in tumor immunosuppressive microenvironment in HGSOC.

METHODS

HGSOC samples were collected, with 274 samples constituting two independent cohorts (training and validation cohorts) and an additional 30 samples utilized to establish patient-derived tumor organoids (PDTOs). We characterized the number and phenotype of JAG2+ TANs by multiplex immunohistochemistry, flow cytometry, and single-cell RNA sequencing (scRNA-seq). We investigated the biological functions of JAG2 in immune evasion using in vitro co-culture systems, flow cytometry, tumor-bearing mouse models, and PDTOs.

RESULTS

JAG2+ TANs expressed elevated levels of immunosuppressive molecules, including programmed cell death ligand 1 and CD14, and had independent prognostic value for the overall survival of patients with HGSOC. scRNA-seq analysis revealed that JAG2+ TANs exhibited a terminally mature phenotype. The infiltration of JAG2+ TANs was positively correlated with the abundance of effector regulatory T cells (eTregs). Interaction with JAG2+ TANs skewed CD4+ T cells towards an eTreg phenotype, a process that was suppressed by the Notch inhibitor LY3039478 and induced by recombinant Jagged2. Furthermore, we demonstrated that JAG2+ TANs enhanced Notch signaling activation, ultimately promoting recombination signal binding protein for immunoglobulin kappa J region (RBPJ)-induced differentiation of naïve CD4+ T cells into eTregs. Clinically, JAG2+ TANs could serve as a biomarker for assessing immunotherapy resistance in various solid tumors. Pharmacological targeting of Notch signaling with LY3039478 or JAG2 neutralization antibodies enhanced the efficacy of programmed cell death protein 1 (PD-1) monoclonal antibodies (mAbs) in both xenograft and PDTO models.

CONCLUSIONS

The emergence of JAG2+ TANs is crucial for the differentiation of eTregs, which triggers immune evasion and resistance to anti-PD-1 therapy. Inhibiting Notch signaling with LY3039478 or JAG2 neutralization antibodies may overcome this anti-PD-1 resistance in HGSOC.

Blood-brain-barrier-crossing lipid nanoparticles for mRNA delivery to the central nervous system

The systemic delivery of mRNA molecules to the central nervous system is challenging as they need to cross the blood-brain barrier (BBB) to reach into the brain. Here we design and synthesize 72 BBB-crossing lipids fabricated by conjugating BBB-crossing modules and amino lipids, and use them to assemble BBB-crossing lipid nanoparticles for mRNA delivery. Screening and structure optimization studies resulted in a lead formulation that has substantially higher mRNA delivery efficiency into the brain than those exhibited by FDA-approved lipid nanoparticles. Studies in distinct mouse models show that these BBB-crossing lipid nanoparticles can transfect neurons and astrocytes of the whole brain after intravenous injections, being well tolerated across several dosage regimens. Moreover, these nanoparticles can deliver mRNA to human brain ex vivo samples. Overall, these BBB-crossing lipid nanoparticles deliver mRNA to neurons and astrocytes in broad brain regions, thereby being a promising platform to treat a range of central nervous system diseases.

Canonical and noncanonical NOTCH signaling in the nongenetic resistance of cancer: distinct and concerted control

Therapeutic resistance in cancer is responsible for numerous cancer deaths in clinical practice. While target mutations are well recognized as the basis of genetic resistance to targeted therapy, nontarget mutation resistance (or nongenetic resistance) remains poorly characterized. Despite its complex and unintegrated mechanisms in the literature, nongenetic resistance is considered from our perspective to be a collective response of innate or acquired resistant subpopulations in heterogeneous tumors to therapy. These subpopulations, e.g., cancer stem-like cells, cancer cells with epithelial-to-mesenchymal transition, and drug-tolerant persisters, are protected by their resistance traits at cellular and molecular levels. This review summarizes recent advances in the research on resistant populations and their resistance traits. NOTCH signaling, as a central regulator of nongenetic resistance, is discussed with a special focus on its canonical maintenance of resistant cancer cells and noncanonical regulation of their resistance traits. This novel view of canonical and noncanonical NOTCH signaling pathways is translated into our proposal of reshaping therapeutic strategies targeting NOTCH signaling in resistant cancer cells. We hope that this review will lead researchers to study the canonical and noncanonical arms of NOTCH signaling as an integrated resistant mechanism, thus promoting the development of innovative therapeutic strategies.

Secretase promotes AD progression: simultaneously cleave Notch and APP

Alzheimer's disease (AD) involves complex pathological mechanisms. Secretases include membrane protein extracellular structural domain proteases and intramembrane proteases that cleave the topology to type I or type II. Secretases can effectively regulate the activation of Notch and amyloid precursor protein (APP), key factors in the progression of AD and cancer. This article systematically summarizes the intracellular localization, cleavage sites and products, and biological functions of six subtypes of secretases (α-secretase, β-secretase, γ-secretase, δ-secretase, ε-secretase, and η-secretase), and for the first time, elucidates the commonalities and differences between these subtypes of secretases. We found that each subtype of secretase primarily cleaves APP and Notch as substrates, regulating Aβ levels through APP cleavage to impact the progression of AD, while also cleaving Notch receptors to affect cancer progression. Finally, we review the chemical structures, indications, and research stages of various secretase inhibitors, emphasizing the promising development of secretase inhibitors in the fields of cancer and AD.

Examining nirogacestat for adults with progressing desmoid tumors who require systemic treatment

INTRODUCTION

Desmoid tumor (DT) is a rare, locally aggressive, mesenchymal neoplasm that can arise at any site in the body. Medical therapies play a major role for DT's patients requiring treatment. A novel systemic approach has recently emerged with Nirogacestat, a γ-secretase inhibitor targeting the NOTCH signaling pathway.

AREAS COVERED

Nirogacestat is the first drug in its class to receive approval from the Food and Drug Administration (FDA) and is the first FDA-approved treatment specifically for DTs. We reviewed the data leading to its discovery, including its mechanism of action, pharmacological properties, clinical efficacy, and its positioning within the current treatment armamentarium for DTs.

EXPERT OPINION

High-quality evidence for systemic therapies in the management of DTs remains an unmet need. Nirogacestat now joins sorafenib as the only drugs with efficacy in DTs demonstrated by randomized phase 3 studies. Currently, there are no comparative trials of the available systemic therapies. Therefore, physicians should consider factors such as drug accessibility, cost, toxicity profile, comorbidities, and patient preferences when selecting treatment. Long-term efficacy and safety data will be essential for evaluating the duration of treatment response and monitoring late-onset side effects of Nirogacestat.

Notch-Targeted Therapeutic in Colorectal Cancer by Notch1 Attenuation Via Tumor Microenvironment-Responsive Cascade DNA Delivery

The Notch signaling is a key molecular pathway that regulates cell fate and development. Aberrant Notch signaling can lead to carcinogenesis and progression of malignant tumors. However, current therapies targeting Notch pathway lack specificity and induce high toxicity. In this report, a tumor microenvironment-responsive and injectable hydrogel is designed to load plasmid DNA complexes as a cascade gene delivery system to achieve precise Notch-targeted gene therapy of colorectal cancer (CRC). The hydrogels are prepared through cross-linking between phenylboric acid groups containing poly(oligo(ethylene glycol)methacrylate) (POEGMA) and epigallocatechin gallate (EGCG), used to load the complexes between plasmid DNA encoding short hairpin RNAs of Notch1 (shNotch1) and fluorinated polyamidoamine (PAMAM-F) (PAMAM-F/shNotch1). In response to low pH and H2O2 in tumor microenvironment, the hydrogel can be dissociated and release the complexes for precise delivery of shNotch1 into tumor cells and inhibit Notch1 activity to suppress malignant biological behaviors of CRC. In the subcutaneous tumor model of CRC, PAMAM-F/shNotch1-loaded hydrogels can accurately attenuate Notch1 activity and significantly inhibit tumor growth without affecting Notch signal in adjacent normal tissues. Therefore, this therapeutic system can precisely inhibit Notch1 signal in CRC with high responsiveness and low toxicity, providing a promising Notch-targeted gene therapeutic for human malignancy.

Combined Treatment of Uterine Leiomyosarcoma with Gamma Secretase Inhibitor MK-0752 and Chemotherapeutic Agents Decreases Cellular Invasion and Increases Apoptosis

Due to limited effective therapeutics for uterine leiomyosarcoma (uLMS), the impact of the gamma secretase inhibitor (GSI) MK-0752 with common chemotherapeutics was explored in uLMS. MTT assays were performed on two human uLMS cell lines, SK-UT-1B and SK-LMS-1, using MK-0752, docetaxel, doxorubicin, and gemcitabine, individually and in combination, to determine cell viability after treatment. Synergistic combinations were used in transwell invasion assays, cell cycle flow cytometry, proliferation assays, and RNA sequencing. In SK-UT-1B, MK-0752 was synergistic with doxorubicin and gemcitabine plus docetaxel. In SK-LMS-1, MK-0752 was synergistic with all individual agents and with the combination of gemcitabine plus docetaxel. MK-0752, gemcitabine, and docetaxel decreased invasion in SK-UT-1B 2.1-fold* and in SK-LMS-1 1.7-fold*. In SK-LMS-1, invasion decreased 1.2-fold* after treatment with MK-0752 and docetaxel and 2.2-fold* after treatment with MK-0752 and doxorubicin. Cell cycle analysis demonstrated increases in the apoptotic sub-G1 population with MK-0752 alone in SK-UT-1B (1.4-fold*) and SK-LMS-1 (2.7-fold**), along with increases with all combinations in both cell lines. The combination treatments had limited effects on proliferation, while MK-0752 alone decreased proliferation in SK-LMS-1 (0.63-fold**). Both MK-0752 alone and in combination altered gene expression and KEGG pathways. In conclusion, the combinations of MK-0752 with either doxorubicin, docetaxel, or gemcitabine plus docetaxel are potential novel therapeutic approaches for uLMS. (* p < 0.05, ** p < 0.01).

Signaling pathways in liver cancer: pathogenesis and targeted therapy

Liver cancer remains one of the most prevalent malignancies worldwide with high incidence and mortality rates. Due to its subtle onset, liver cancer is commonly diagnosed at a late stage when surgical interventions are no longer feasible. This situation highlights the critical role of systemic treatments, including targeted therapies, in bettering patient outcomes. Despite numerous studies on the mechanisms underlying liver cancer, tyrosine kinase inhibitors (TKIs) are the only widely used clinical inhibitors, represented by sorafenib, whose clinical application is greatly limited by the phenomenon of drug resistance. Here we show an in-depth discussion of the signaling pathways frequently implicated in liver cancer pathogenesis and the inhibitors targeting these pathways under investigation or already in use in the management of advanced liver cancer. We elucidate the oncogenic roles of these pathways in liver cancer especially hepatocellular carcinoma (HCC), as well as the current state of research on inhibitors respectively. Given that TKIs represent the sole class of targeted therapeutics for liver cancer employed in clinical practice, we have particularly focused on TKIs and the mechanisms of the commonly encountered phenomena of its resistance during HCC treatment. This necessitates the imperative development of innovative targeted strategies and the urgency of overcoming the existing limitations. This review endeavors to shed light on the utilization of targeted therapy in advanced liver cancer, with a vision to improve the unsatisfactory prognostic outlook for those patients.

Notch signaling pathway in cancer: from mechanistic insights to targeted therapies

Notch signaling, renowned for its role in regulating cell fate, organ development, and tissue homeostasis across metazoans, is highly conserved throughout evolution. The Notch receptor and its ligands are transmembrane proteins containing epidermal growth factor-like repeat sequences, typically necessitating receptor-ligand interaction to initiate classical Notch signaling transduction. Accumulating evidence indicates that the Notch signaling pathway serves as both an oncogenic factor and a tumor suppressor in various cancer types. Dysregulation of this pathway promotes epithelial-mesenchymal transition and angiogenesis in malignancies, closely linked to cancer proliferation, invasion, and metastasis. Furthermore, the Notch signaling pathway contributes to maintaining stem-like properties in cancer cells, thereby enhancing cancer invasiveness. The regulatory role of the Notch signaling pathway in cancer metabolic reprogramming and the tumor microenvironment suggests its pivotal involvement in balancing oncogenic and tumor suppressive effects. Moreover, the Notch signaling pathway is implicated in conferring chemoresistance to tumor cells. Therefore, a comprehensive understanding of these biological processes is crucial for developing innovative therapeutic strategies targeting Notch signaling. This review focuses on the research progress of the Notch signaling pathway in cancers, providing in-depth insights into the potential mechanisms of Notch signaling regulation in the occurrence and progression of cancer. Additionally, the review summarizes pharmaceutical clinical trials targeting Notch signaling for cancer therapy, aiming to offer new insights into therapeutic strategies for human malignancies.

Breast cancer stem cells as novel biomarkers

Breast cancer is the most common cancer and the leading cause of mortality worldwide. Despite advancements in detection and treatment, it remains a major cause of cancer-related deaths in women. Breast cancer stem cells (BCSCs) are a crucial group of cells responsible for carcinogenesis, metastasis, medication resistance, and tumor recurrence. Identifying and understanding their molecular pathways is essential for developing effective breast cancer therapy. BCSCs are responsible for tumor genesis, development, metastasis, treatment resistance, and recurrence. Biomarkers are essential tools for identifying high-risk patients, improving diagnostic accuracy, developing follow-up programs, assessing treatment susceptibility, and predicting prognostic outcomes. Stem cell intervention therapy can provide specialized tools for precision therapy. Biomarker analysis in cancer patients is crucial to identify cells associated with disease progression and post-therapeutic relapse. However, negative post-therapeutic impacts can enhance cancer stemness by boosting BCSCs plasticity phenotypes, activating stemness pathways in non-BCSCs, and promoting senescence escape, leading to tumor relapse and metastasis. Despite the advancements in precision medicine, challenges persist in identifying stem cell markers, limiting the number of eligible patients for treatment. The diversity of biomedical research hinders the development of individualization-based preventative, monitoring, and treatment strategies, especially in oncology. Integrating and interpreting clinical and scientific data remains challenging. The development of stem cell-related indicators could significantly improve disease precision, enabling stem cell-targeted therapy and personalized treatment plans, although BCSCs are promising for breast cancer treatment optimization, serving as biomarkers for current therapy modalities. This summary discusses recent advancements in breast cancer stem cell research, including biomarkers, identification methods, molecular mechanisms, and tools for studying their biological origin and lineage development for precision medicine.

Informed by Cancer Stem Cells of Solid Tumors: Advances in Treatments Targeting Tumor-Promoting Factors and Pathways

Cancer stem cells (CSCs) represent a subpopulation within tumors that promote cancer progression, metastasis, and recurrence due to their self-renewal capacity and resistance to conventional therapies. CSC-specific markers and signaling pathways highly active in CSCs have emerged as a promising strategy for improving patient outcomes. This review provides a comprehensive overview of the therapeutic targets associated with CSCs of solid tumors across various cancer types, including key molecular markers aldehyde dehydrogenases, CD44, epithelial cellular adhesion molecule, and CD133 and signaling pathways such as Wnt/β-catenin, Notch, and Sonic Hedgehog. We discuss a wide array of therapeutic modalities ranging from targeted antibodies, small molecule inhibitors, and near-infrared photoimmunotherapy to advanced genetic approaches like RNA interference, CRISPR/Cas9 technology, aptamers, antisense oligonucleotides, chimeric antigen receptor (CAR) T cells, CAR natural killer cells, bispecific T cell engagers, immunotoxins, drug-antibody conjugates, therapeutic peptides, and dendritic cell vaccines. This review spans developments from preclinical investigations to ongoing clinical trials, highlighting the innovative targeting strategies that have been informed by CSC-associated pathways and molecules to overcome therapeutic resistance. We aim to provide insights into the potential of these therapies to revolutionize cancer treatment, underscoring the critical need for a multi-faceted approach in the battle against cancer. This comprehensive analysis demonstrates how advances made in the CSC field have informed significant developments in novel targeted therapeutic approaches, with the ultimate goal of achieving more effective and durable responses in cancer patients.

Clinical impact of epithelial–mesenchymal transition for cancer therapy

The epithelial–mesenchymal transition (EMT) represents a pivotal frontier in oncology, playing a central role in the metastatic cascade of cancer—a leading global health challenge. This comprehensive review delves into the complexities of EMT, a process where cancer cells gain exceptional mobility, facilitating their invasion into distant organs and the establishment of secondary malignancies. We thoroughly examine the myriad of factors influencing EMT, encompassing transcription factors, signalling pathways, metabolic alterations, microRNAs, long non‐coding RNAs, epigenetic changes, exosomal interactions and the intricate dynamics of the tumour microenvironment. Particularly, the review emphasises the advanced stages of EMT, crucial for the development of highly aggressive cancer phenotypes. During this phase, cancer cells penetrate the vascular barrier and exploit the bloodstream to propagate life‐threatening metastases through the mesenchymal–epithelial transition. We also explore EMT's significant role in fostering tumour dormancy, senescence, the emergence of cancer stem cells and the formidable challenge of therapeutic resistance. Our review transcends a mere inventory of EMT‐inducing elements; it critically assesses the current state of EMT‐focused clinical trials, revealing both the hurdles and significant breakthroughs. Highlighting the potential of EMT research, we project its transformative impact on the future of cancer therapy. This exploration is aimed at paving the way towards an era of effectively managing this relentless disease, positioning EMT at the forefront of innovative cancer research strategies.

Recent advances in drug delivery and targeting for the treatment of pancreatic cancer

Despite significant treatment efforts, pancreatic ductal adenocarcinoma (PDAC), the deadliest solid tumor, is still incurable in the preclinical stages due to multifacet stroma, dense desmoplasia, and immune regression. Additionally, tumor heterogeneity and metabolic changes are linked to low grade clinical translational outcomes, which has prompted the investigation of the mechanisms underlying chemoresistance and the creation of effective treatment approaches by selectively targeting genetic pathways. Since targeting upstream molecules in first-line oncogenic signaling pathways typically has little clinical impact, downstream signaling pathways have instead been targeted in both preclinical and clinical studies. In this review, we discuss how the complexity of various tumor microenvironment (TME) components and the oncogenic signaling pathways that they are connected to actively contribute to the development and spread of PDAC, as well as the ways that recent therapeutic approaches have been targeted to restore it. We also illustrate how many endogenous stimuli-responsive linker-based nanocarriers have recently been developed for the specific targeting of distinct oncogenes and their downstream signaling cascades as well as their ongoing clinical trials. We also discuss the present challenges, prospects, and difficulties in the development of first-line oncogene-targeting medicines for the treatment of pancreatic cancer patients.

Deregulated transcription factors in the emerging cancer hallmarks

Cancer progression is a multifaceted process that entails several stages and demands the persistent expression or activation of transcription factors (TFs) to facilitate growth and survival. TFs are a cluster of proteins with DNA-binding domains that attach to promoter or enhancer DNA strands to start the transcription of genes by collaborating with RNA polymerase and other supporting proteins. They are generally acknowledged as the major regulatory molecules that coordinate biological homeostasis and the appropriate functioning of cellular components, subsequently contributing to human physiology. TFs proteins are crucial for controlling transcription during the embryonic stage and development, and the stability of different cell types depends on how they function in different cell types. The development and progression of cancer cells and tumors might be triggered by any anomaly in transcription factor function. It has long been acknowledged that cancer development is accompanied by the dysregulated activity of TF alterations which might result in faulty gene expression. Recent studies have suggested that dysregulated transcription factors play a major role in developing various human malignancies by altering and rewiring metabolic processes, modifying the immune response, and triggering oncogenic signaling cascades. This review emphasizes the interplay between TFs involved in metabolic and epigenetic reprogramming, evading immune attacks, cellular senescence, and the maintenance of cancer stemness in cancerous cells. The insights presented herein will facilitate the development of innovative therapeutic modalities to tackle the dysregulated transcription factors underlying cancer.

Oncofetal reprogramming in tumor development and progression: novel insights into cancer therapy

Emerging evidence indicates that cancer cells can mimic characteristics of embryonic development, promoting their development and progression. Cancer cells share features with embryonic development, characterized by robust proliferation and differentiation regulated by signaling pathways such as Wnt, Notch, hedgehog, and Hippo signaling. In certain phase, these cells also mimic embryonic diapause and fertilized egg implantation to evade treatments or immune elimination and promote metastasis. Additionally, the upregulation of ATP-binding cassette (ABC) transporters, including multidrug resistance protein 1 (MDR1), multidrug resistance-associated protein 1 (MRP1), and breast cancer-resistant protein (BCRP), in drug-resistant cancer cells, analogous to their role in placental development, may facilitate chemotherapy efflux, further resulting in treatment resistance. In this review, we concentrate on the underlying mechanisms that contribute to tumor development and progression from the perspective of embryonic development, encompassing the dysregulation of developmental signaling pathways, the emergence of dormant cancer cells, immune microenvironment remodeling, and the hyperactivation of ABC transporters. Furthermore, we synthesize and emphasize the connections between cancer hallmarks and embryonic development, offering novel insights for the development of innovative cancer treatment strategies.

Systematic analysis reveals distinct roles of USF family proteins in various cancer types

BACKGROUND

Upstream stimulatory factors (USFs) are members of the basic helix-loop-helix leucine zipper transcription factor family, including USF1, USF2, and USF3. The first two members have been well studied compared to the third member, USF3, which has received scarce attention in cancer research to date. Despite a recently reported association of its alteration with thyroid carcinoma, its expression has not been previously analyzed.

METHODS

We comprehensively analyzed differential levels of USFs expression, genomic alteration, DNA methylation, and their prognostic value across different cancer types and the possible correlation with tumor-infiltrating immune cells and drug response by using different bioinformatics tools.

RESULTS

Our findings established that USFs play an important role in cancers related to the urinary system and justify the necessity for further investigation. We implemented and offer a useful ShinyApp to facilitate researchers' efforts to inquire about any other gene of interest and to perform the analysis of drug response in a user-friendly fashion at http://zzdlab.com:3838/Drugdiscovery/.

Signalling in pancreatic cancer: from pathways to therapy

Pancreatic cancer (PC) is a common malignant tumour in the digestive system. Due to the lack of sensitive diagnostic markers, strong metastasis ability, and resistance to anti-cancer drugs, the prognosis of PC is inferior. In the past decades, increasing evidence has indicated that the development of PC is closely related to various signalling pathways. With the exploration of RAS-driven, epidermal growth factor receptor, Hedgehog, NF-κB, TGF-β, and NOTCH signalling pathways, breakthroughs have been made to explore the mechanism of pancreatic carcinogenesis, as well as the novel therapies. In this review, we discussed the signalling pathways involved in PC and summarised current targeted agents in the treatment of PC. Furthermore, opportunities and challenges in the exploration of potential therapies targeting signalling pathways were also highlighted.

The m6A reader IGF2BP3 preserves NOTCH3 mRNA stability to sustain Notch3 signaling and promote tumor metastasis in nasopharyngeal carcinoma

Metastasis remains the major cause of treatment failure in patients with nasopharyngeal carcinoma (NPC), in which sustained activation of the Notch signaling plays a critical role. N6-Methyladenosine (m6A)-mediated post-transcriptional regulation is involved in fine-tuning the Notch signaling output; however, the post-transcriptional mechanisms underlying NPC metastasis remain poorly understood. In the present study, we report that insulin-like growth factor 2 mRNA-binding proteins 3 (IGF2BP3) serves as a key m6A reader in NPC. IGF2BP3 expression was significantly upregulated in metastatic NPC and correlated with poor prognosis in patients with NPC. IGF2BP3 overexpression promoted, while IGF2BP3 downregulation inhibited tumor metastasis and the stemness phenotype of NPC cells in vitro and in vivo. Mechanistically, IGF2BP3 maintains NOTCH3 mRNA stability via suppression of CCR4-NOT complex-mediated deadenylation in an m6A-dependent manner, which sustains Notch3 signaling activation and increases the transcription of stemness-associated downstream genes, eventually promoting tumor metastasis. Our findings highlight the pro-metastatic function of the IGF2BP3/Notch3 axis and revealed the precise role of IGF2BP3 in post-transcriptional regulation of NOTCH3, suggesting IGF2BP3 as a novel prognostic biomarker and potential therapeutic target in NPC metastasis.

In vitro antineoplastic effects of MK0752 in HPV-positive head and neck squamous cell carcinoma

PURPOSE

Gamma-secretase inhibitor MK0752 has shown a high therapeutic potential in different solid malignant tumors. Up to now, its antineoplastic effects were not investigated in head and neck squamous cell carcinoma (HNSCC) and particularly in human-papillomavirus (HPV)-positive tumors.

METHODS

We conducted cytotoxic, migration, and clonogenic assays in two HPV-negative HNSCC cell lines (Cal27 and FaDu) and one HPV-positive cell line (SCC154). Furthermore, in order to assess the pro-apoptotic effects of MK0752, a Caspase 3/7 Glo assay was performed.

RESULTS

Our experiments revealed antineoplastic effects of MK0752 in all three cell lines. Strong cytotoxic and antimigratory potential was shown in all cell lines, with strongest effects observed in the HPV-positive cell line. Meanwhile, anticlonogenic effects were only shown in Cal27 and SCC154. Most importantly, MK0752 induced apoptosis solely in HPV-positive SCC154.

CONCLUSIONS

Our novel findings indicate a therapeutic potential of MK0752 in HPV-positive HNSCC. Indeed, further investigation is needed for validation of our results and for the assessment of the mechanistic background.

The strategies to cure cancer patients by eradicating cancer stem-like cells

Cancer stem-like cells (CSCs), a subpopulation of cancer cells, possess remarkable capability in proliferation, self-renewal, and differentiation. Their presence is recognized as a crucial factor contributing to tumor progression and metastasis. CSCs have garnered significant attention as a therapeutic focus and an etiologic root of treatment-resistant cells. Increasing evidence indicated that specific biomarkers, aberrant activated pathways, immunosuppressive tumor microenvironment (TME), and immunoevasion are considered the culprits in the occurrence of CSCs and the maintenance of CSCs properties including multi-directional differentiation. Targeting CSC biomarkers, stemness-associated pathways, TME, immunoevasion and inducing CSCs differentiation improve CSCs eradication and, therefore, cancer treatment. This review comprehensively summarized these targeted therapies, along with their current status in clinical trials. By exploring and implementing strategies aimed at eradicating CSCs, researchers aim to improve cancer treatment outcomes and overcome the challenges posed by CSC-mediated therapy resistance.

The critical role of γ-secretase and its inhibitors in cancer and cancer therapeutics

As a multi-substrate transmembrane protease, γ-secretase exists widely in various cells. It controls multiple important cellular activities through substrate cleavage. γ-secretase inhibitors (GSIs) play a role in cancer inhibition by blocking Notch cleavage, and are considered as potential therapeutic strategies for cancer. Currently, GSIs have encouraging performance in preclinical models, yet this success does not translate well in clinical trials. In recent years, a number of breakthrough discoveries have shown us the promise of targeting γ-secretase for the treatment of cancer. Here, we integrate a large amount of data from γ-secretase and its inhibitors and cancer in nearly 30 years, comb and discuss the close connection between γ-secretase and cancer, as well as the potential and problems of current GSIs in cancer treatment. We analyze the possible reasons for the failure performance of current GSIs in clinical trials, and make recommendations for future research areas.

A microprotein N1DARP encoded by LINC00261 promotes Notch1 intracellular domain (N1ICD) degradation via disrupting USP10-N1ICD interaction to inhibit chemoresistance in Notch1-hyperactivated pancreatic cancer

The extensively activated Notch signaling pathway in pancreatic cancer cells is important in carcinogenesis, chemoresistance, and recurrence. Targeting this pathway is a promising therapeutic strategy for pancreatic cancer; however, few successful approaches have been reported, and currently used molecular inhibitors of this pathway exhibit limited clinical benefits. In this study, we identified a previously uncharacterized microprotein, Notch1 degradation-associated regulatory polypeptide (N1DARP), encoded by LINC00261. N1DARP knockout accelerated tumor progression and enhanced stem cell properties in pancreatic cancer organoids and LSL-Kras, LSL-Trp53, and Pdx1-Cre (KPC) mice. Mechanistically, N1DARP suppressed canonical and non-canonical Notch1 pathways by competitively disrupting the interaction between N1ICD and ubiquitin-specific peptidase 10 (USP10), thereby promoting K11- and K48-linked polyubiquitination of N1ICD. To evaluate the therapeutic potential of N1DARP, we designed a cell-penetrating stapled peptide, SAH-mAH2-5, with a helical structure similar to that of N1DARP that confers remarkable physicochemical stability. SAH-mAH2-5 interacted with and promoted the proteasome-mediated degradation of N1ICD. SAH-mAH2-5 injection provided substantial therapeutic benefits with limited off-target and systemic adverse effects in Notch1-activated pancreatic cancer models. Taken together, these findings confirm that N1DARP acts as a tumor suppressor and chemosensitizer by regulating USP10-Notch1 oncogenic signaling, and suggest a promising therapeutic strategy targeting the N1DARP-N1ICD interaction in Notch1-activated pancreatic cancer.

LIN28B promotes cell invasion and colorectal cancer metastasis via CLDN1 and NOTCH3

The RNA-binding protein LIN28B is overexpressed in over 30% of patients with colorectal cancer (CRC) and is associated with poor prognosis. In the present study, we unraveled a potentially novel mechanism by which LIN28B regulates colonic epithelial cell-cell junctions and CRC metastasis. Using human CRC cells (DLD-1, Caco-2, and LoVo) with either knockdown or overexpression of LIN28B, we identified claudin 1 (CLDN1) tight junction protein as a direct downstream target and effector of LIN28B. RNA immunoprecipitation revealed that LIN28B directly binds to and posttranscriptionally regulates CLDN1 mRNA. Furthermore, using in vitro assays and a potentially novel murine model of metastatic CRC, we show that LIN28B-mediated CLDN1 expression enhances collective invasion, cell migration, and metastatic liver tumor formation. Bulk RNA sequencing of the metastatic liver tumors identified NOTCH3 as a downstream effector of the LIN28B/CLDN1 axis. Additionally, genetic and pharmacologic manipulation of NOTCH3 signaling revealed that NOTCH3 was necessary for invasion and metastatic liver tumor formation. In summary, our results suggest that LIN28B promotes invasion and liver metastasis of CRC by posttranscriptionally regulating CLDN1 and activating NOTCH3 signaling. This discovery offers a promising new therapeutic option for metastatic CRC to the liver, an area where therapeutic advancements have been relatively scarce.

Pancreatic cancer stemness: dynamic status in malignant progression

Pancreatic cancer (PC) is one of the most aggressive malignancies worldwide. Increasing evidence suggests that the capacity for self-renewal, proliferation, and differentiation of pancreatic cancer stem cells (PCSCs) contribute to major challenges with current PC therapies, causing metastasis and therapeutic resistance, leading to recurrence and death in patients. The concept that PCSCs are characterized by their high plasticity and self-renewal capacities is central to this review. We focused specifically on the regulation of PCSCs, such as stemness-related signaling pathways, stimuli in tumor cells and the tumor microenvironment (TME), as well as the development of innovative stemness-targeted therapies. Understanding the biological behavior of PCSCs with plasticity and the molecular mechanisms regulating PC stemness will help to identify new treatment strategies to treat this horrible disease.

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.

Recent advances in targeted therapy for pancreatic adenocarcinoma

Pancreatic adenocarcinoma (PDAC) is a fatal disease with a 5-year survival rate of 8% and a median survival of 6 mo. In PDAC, several mutations in the genes are involved, with Kirsten rat sarcoma oncogene (90%), cyclin-dependent kinase inhibitor 2A (90%), and tumor suppressor 53 (75%–90%) being the most common. Mothers against decapentaplegic homolog 4 represents 50%. In addition, the self-preserving cancer stem cells, dense tumor microenvironment (fibrous accounting for 90% of the tumor volume), and suppressive and relatively depleted immune niche of PDAC are also constitutive and relevant elements of PDAC. Molecular targeted therapy is widely utilized and effective in several solid tumors. In PDAC, targeted therapy has been extensively evaluated; however, survival improvement of this aggressive disease using a targeted strategy has been minimal. There is currently only one United States Food and Drug Administration-approved targeted therapy for PDAC – erlotinib, but the absolute benefit of erlotinib in combination with gemcitabine is also minimal (2 wk). In this review, we summarize current targeted therapies and clinical trials targeting dysregulated signaling pathways and components of the PDAC oncogenic process, analyze possible reasons for the lack of positive results in clinical trials, and suggest ways to improve them. We also discuss emerging trends in targeted therapies for PDAC: combining targeted inhibitors of multiple pathways. The PubMed database and National Center for Biotechnology Information clinical trial website (www.clinicaltrials.gov) were queried to identify completed and published (PubMed) and ongoing (clinicaltrials.gov) clinical trials (from 2003-2022) using the keywords pancreatic cancer and targeted therapy. The PubMed database was also queried to search for information about the pathogenesis and molecular pathways of pancreatic cancer using the keywords pancreatic cancer and molecular pathways.

Arsenic trioxide elicits anti-tumor activity by inhibiting polarization of M2-like tumor-associated macrophages via Notch signaling pathway in lung adenocarcinoma

Drug-resistant advanced lung adenocarcinoma (LUAD) is an aggressive malignancy with limited treatment options. A therapeutic strategy for drug-resistant LUAD is to target the tumor associated macrophages (TAMs), because they play an important role in tumor immune escape, progression and metastasis. In this study, we conducted in vivo and in vitro investigation of the inhibitory effect of arsenic trioxide (ATO) on polarization of TAMs educated by LUAD. We found that ATO at a concentration of 4 μM disrupted the Notch-dependent positive feedback loop between LUAD and TAMs. In this loop, ATO inhibited the expression of Jagged1 and Notch1 in LUAD and suppressed M2 polarization via down-regulating Notch-dependent paracrine of CCL2 and IL1β. As a result, the secretion of M2-derived TGF-β1 decreased, thus inducing inhibitions of LUAD proliferation, migration, invasion, colony formation and epithelial-mesenchymal transition. In xenograft mouse models, ATO significantly inhibited tumor growth and down-regulated infiltration of M2-like TAMs in tumor tissues. In clinical LUAD biopsy samples, high Jagged1/Notch1 expression positively correlated with tumor-infiltrated M2-like TAMs, leading to poor prognosis. In conclusion, our results identified a novel tumor immunomodulating function for ATO, which can inhibit the polarization of M2-type TAMs to exert anti-tumor effects in the tumor microenvironment. Our results demonstrated the translational potential of repurposing ATO to target TAMs for lung adenocarcinoma treatment.

Nanomedicines Targeting Glioma Stem Cells

Glioblastoma (GBM), classified as a grade IV glioma, is a rapidly growing, aggressive, and most commonly occurring tumor of the central nervous system. Despite the therapeutic advances, it carries an ominous prognosis, with a median survival of 14.6 months after diagnosis. Accumulating evidence suggests that cancer stem cells in GBM, termed glioma stem cells (GSCs), play a crucial role in tumor propagation, treatment resistance, and tumor recurrence. GSCs, possessing the capacity for self-renewal and multilineage differentiation, are responsible for tumor growth and heterogeneity, leading to primary obstacles to current cancer therapy. In this respect, increasing efforts have been devoted to the development of anti-GSC strategies based on targeting GSC surface markers, blockage of essential signaling pathways of GSCs, and manipulating the tumor microenvironment (GSC niches). In this review, we will discuss the research knowledge regarding GSC-based therapy and the underlying mechanisms for the treatment of GBM. Given the rapid progression in nanotechnology, innovative nanomedicines developed for GSC targeting will also be highlighted from the perspective of rationale, advantages, and limitations. The goal of this review is to provide broader understanding and key considerations toward the future direction of GSC-based nanotheranostics to fight against GBM.

Targeting the DLL/Notch Signaling Pathway in Cancer: Challenges and Advances in Clinical Development

The DLL/Notch signaling pathway plays an important role in cancer as a key driver in maintaining cancer stemness and inducing tumor angiogenesis. Many different types of DLL/Notch inhibitors have been developed and explored in clinical trials for cancer treatment, including small-molecule compounds to inhibit gamma-secretase and antibodies targeting Notch ligands or receptors. Despite promising efficacy of these inhibitors in preclinical studies, the overall clinical outcomes have been insufficient to advance to the next stage of clinical development primarily due to safety concerns or modest efficacy. To overcome the narrow therapeutic window of DLL/Notch inhibitors, diverse strategies for improving the balance between the safety and efficacy are currently being explored. Here, we review the clinical perspective and potential of DLL/Notch inhibitors as anticancer agents based on recent results from multiple clinical studies. An antibody specifically targeting Notch ligands or receptors may offer a better approach to reduce concerns about toxicity derived from broad-spectrum DLL/Notch blockers. In addition, combination therapy with an angiogenesis inhibitor targeting VEGF could be a better option for increasing anticancer efficacy. Taken together, the results of clinical trials suggest a bispecific antibody blocking the DLL/Notch and VEGF/VEGFR signaling pathways as a promising approach for effective anticancer treatment.

NEPHROPROTECTIVE EFFECT OF GAMMA-SECRETASE INHIBITOR ON SEPSIS- INDUCED RENAL INJURY IN MOUSE MODEL OF CLP

OBJECTIVE

The aim: This study was set out to assess the potential protective impact of MK0752 (a gamma secretase inhibitor) on sepsis-induced renal injury through modulation of inflammatory and oxidative stress pathways.

PATIENTS AND METHODS

Materials and methods: Twenty-four Swiss-albino mice aged between eight and twelve week and weighted twenty to thirty-seven grams were randomly allocated into four groups (n=6 in each group). Sham group (laparotomy without cecal ligation and puncture (CLP), sepsis group (laparotomy with CLP), vehicle-treated group (equivalent volume of DMSO before the CLP), MK0752 treated group (5 mg/kg) single daily dose for three days before the CLP. Blood samples were used to assess the serum levels of urea and creatinine. The kidneys were used to assess tissue levels of the TNF-α, IL-10, IL-6, TNFR1, VEGF, notch1, jagged1 and tissue damage by histopathological analysis.

RESULTS

Results: The current study shows that pretreatment with MK0752 ameliorates the renal damage by significantly reducing the proinflammatory cytokines and notch1 signaling.

CONCLUSION

Conclusions: Taken together, these results suggest that MK0752 could be protective against the renal injury induced by sepsis through its ameliorative impact on renal architecture and modulating cytokines and Notch1 singling pathway. Further studies regarding the role of Notch signaling pathways would be worthwhile.

Pancreatic Cancer: Beyond Brca Mutations

Pancreatic cancer is the fourth-leading cause of cancer-related deaths worldwide. The outcomes in patients with pancreatic cancer remain unsatisfactory. In the current review, we summarize the genetic and epigenetic architecture of metastatic pancreatic cancer beyond the BRCA mutations, focusing on the genetic alterations and the molecular pathology in pancreatic cancer. This review focuses on the molecular targets for the treatment of pancreatic cancer, with a correlation to future treatments. The potential approach addressed in this review may lead to the identification of a subset of patients with specific biological behaviors and treatment responses.

A Gold Nanoparticle Bioconjugate Delivery System for Active Targeted Photodynamic Therapy of Cancer and Cancer Stem Cells

Cancer stem cells (CSCs), also called tumor-initiating cells, are a subpopulation of cancer cells believed to be the leading cause of cancer initiation, growth, metastasis, and recurrence. Presently there are no effective treatments targeted at eliminating CSCs. Hence, an urgent need to develop measures to target CSCs to eliminate potential recurrence and metastasis associated with CSCs. Cancer stem cells have inherent and unique features that differ from other cancer cells, which they leverage to resist conventional therapies. Targeting such features with photodynamic therapy (PDT) could be a promising treatment for drug-resistant cancer stem cells. Photodynamic therapy is a light-mediated non-invasive treatment modality. However, PDT alone is unable to eliminate cancer stem cells effectively, hence the need for a targeted approach. Gold nanoparticle bioconjugates with PDT could be a potential approach for targeted photodynamic therapy of cancer and CSCs. This approach has the potential for enhanced drug delivery, selective and specific attachment to target tumor cells/CSCs, as well as the ability to efficiently generate ROS. This review examines the impact of a smart gold nanoparticle bioconjugate coupled with a photosensitizer (PS) in promoting targeted PDT of cancer and CSC.

The emerging role of NOTCH3 receptor signalling in human lung diseases

The mammalian respiratory system or lung is a tree-like branching structure, and the main site of gas exchange with the external environment. Structurally, the lung is broadly classified into the proximal (or conducting) airways and the distal alveolar region, where the gas exchange occurs. In parallel with the respiratory tree, the pulmonary vasculature starts with large pulmonary arteries that subdivide rapidly ending in capillaries adjacent to alveolar structures to enable gas exchange. The NOTCH signalling pathway plays an important role in lung development, differentiation and regeneration post-injury. Signalling via the NOTCH pathway is mediated through activation of four NOTCH receptors (NOTCH1-4), with each receptor capable of regulating unique biological processes. Dysregulation of the NOTCH pathway has been associated with development and pathophysiology of multiple adult acute and chronic lung diseases. This includes accumulating evidence that alteration of NOTCH3 signalling plays an important role in the development and pathogenesis of chronic obstructive pulmonary disease, lung cancer, asthma, idiopathic pulmonary fibrosis and pulmonary arterial hypertension. Herein, we provide a comprehensive summary of the role of NOTCH3 signalling in regulating repair/regeneration of the adult lung, its association with development of lung disease and potential therapeutic strategies to target its signalling activity.

A γ-Secretase Inhibitor Attenuates Cell Cycle Progression and Invasion in Human Oral Squamous Cell Carcinoma: An In Vitro Study

Notch signaling is associated with many human malignancies, including oral squamous cell carcinoma (OSCC). However, the exact function of Notch signaling in OSCC remains unclear. Here, we investigated the effect of Notch signaling inhibition using a γ-secretase inhibitor (DAPT) on OSCC behaviours in vitro. Bioinformatic analysis of public-available gene expression profiles revealed the dysregulation of the Notch signaling pathway in OSCC compared with normal tissues, indicating the role of Notch signaling in OSCC regulation. RNA sequencing analysis of DAPT-treated human OSCC cells revealed the dysregulation of genes related to cell cycle-related pathways. Blocking Notch signaling significantly inhibited cell proliferation. DAPT-induced G0/G1 cell cycle arrest induced cell apoptosis. Furthermore, cell migration and invasion were also reduced in DAPT-treated cells. These findings indicate that Notch signaling activation participates in OSCC regulation by promoting cell growth, cell cycle progression, cell migration, and invasion. These mechanisms could facilitate OSCC progression. These results imply the potential use of Notch signaling inhibitors as a candidate adjuvant treatment in OSCC patients.

Gamma Secretase Inhibitors as Potential Therapeutic Targets for Notch Signaling in Uterine Leiomyosarcoma

Uterine leiomyosarcoma (uLMS) is a rare and aggressive cancer with few effective therapeutics. The Notch signaling pathway is evolutionarily conserved with oncogenic properties, but it has not been well studied in uLMS. The purpose of our study was to determine expression of Notch family genes and proteins and to investigate the therapeutic effect of γ-secretase inhibitors (GSIs), indirect inhibitors of Notch signaling, in uLMS. We determined expression of Notch genes and proteins in benign uterine smooth muscle tissue, fibroids, and uLMS samples by immunostaining and in two uLMS cell lines, SK-UT-1B (uterine primary) and SK-LMS-1 (vulvar metastasis) by RT-PCR, Western blot and immunostaining. We exposed our cell lines to GSIs, DAPT and MK-0752, and measured expression of HES1, a downstream effector of Notch. Notch proteins were differentially expressed in uLMS. Expression of NOTCH3 and NOTCH4 was higher in uLMS samples than in benign uterine smooth muscle and fibroids. Expression of NOTCH4 was higher in SK-LMS-1 compared to SK-UT-1B. Exposure of SK-UT-1B and SK-LMS-1 to DAPT and MK-0752 decreased expression of HES1 and decreased uLMS cell viability in a dose- and time-dependent manner that was unique to each GSI. Our findings suggest that GSIs are potential therapeutics for uLMS, albeit with limited efficacy.

The role of Jagged1 as a dynamic switch of cancer cell plasticity in PDAC assembloids

Background: Pancreatic ductal adenocarcinoma (PDAC), which commonly relapses due to chemotherapy resistance, has a poor 5-year survival rate (< 10%). The ability of PDAC to dynamically switch between cancer-initiating cell (CIC) and non-CIC states, which is influenced by both internal and external events, has been suggested as a reason for the low drug efficacy. However, cancer cell plasticity using patient-derived PDAC organoids remains poorly understood. Methods: First, we successfully differentiated CICs, which were the main components of PDAC organoids, toward epithelial ductal carcinomas. We further established PDAC assembloids of organoid-derived differentiated ductal cancer cells with endothelial cells (ECs) and autologous immune cells. To investigate the mechanism for PDAC plasticity, we performed single-cell RNA sequencing analysis after culturing the assembloids for 7 days. Results: In the PDAC assembloids, the ECs and immune cells acted as tumor-supporting cells and induced plasticity in the differentiated ductal carcinomas. We also observed that the transcriptome dynamics during PDAC re-programming were related to the WNT/beta-catenin pathway and apoptotic process. Interestingly, we found that WNT5B in the ECs was highly expressed by trans interaction with a JAG1. Furthermore, JAG1 was highly expressed on PDAC during differentiation, and NOTCH1/NOTCH2 were expressed on the ECs at the same time. The WNT5B expression level correlated positively with those of JAG1, NOTCH1, and NOTCH2, and high JAG1 expression correlated with poor survival. Additionally, we experimentally demonstrated that neutralizing JAG1 inhibited cancer cell plasticity. Conclusions: Our results indicate that JAG1 on PDAC plays a critical role in cancer cell plasticity and maintenance of tumor heterogeneity.

Role of Presenilin-1 in Aggressive Human Melanoma

Presenilin-1 (PS-1), a component of the gamma (γ)-secretase catalytic complex, has been implicated in Alzheimer’s disease (AD) and in tumorigenesis. Interestingly, AD risk is inversely related to melanoma, suggesting that AD-related factors, such as PS-1, may affect melanomagenesis. PS-1 has been shown to reduce Wnt activity by promoting degradation of beta-catenin (β-catenin), an important Wnt signaling partner. Since Wnt is known to enhance progression of different cancers, including melanoma, we hypothesized that PS-1 could affect Wnt-associated melanoma aggressiveness. Western blot results showed that aggressive melanoma cells expressed significantly lower levels of both PS-1 and phosphorylated-β-catenin (P-β-catenin) than nonaggressive melanoma cells. Immunohistochemistry of human melanoma samples showed significantly reduced staining for PS-1 in advanced stage melanoma compared with early stage melanoma. Furthermore, γ-secretase inhibitor (GSI) treatment of aggressive melanoma cells was followed by significant increases in PS-1 and P-β-catenin levels, suggesting impaired Wnt signaling activity as PS-1 expression increased. Finally, a significant reduction in cell migration was associated with the higher levels of PS-1 and P-β-catenin in the GSI-treated aggressive melanoma cells. We demonstrate for the first time that PS-1 levels can be used to assess melanoma aggressiveness and suggest that by enhancing PS-1 expression, Wnt-dependent melanoma progression may be reduced

A novel peptide inhibitor of Dll4-Notch1 signalling and its pro-angiogenic functions

BACKGROUND AND PURPOSE

The Dll4-Notch1 signalling pathway plays an important role in sprouting angiogenesis, vascular remodelling and arterial or venous specificity. Genetic or pharmacological inhibition of Dll4-Notch1 signalling leads to excessive sprouting angiogenesis. However, transcriptional inhibitors of Dll4-Notch1 signalling have not been described.

EXPERIMENTAL APPROACH

We designed a new peptide targeting Notch signalling, referred to as TAT-ANK, and assessed its effects on angiogenesis. In vitro, tube formation and fibrin gel bead assay were carried out, using human umbilical vein endothelial cells (HUVECs). In vivo, Matrigel plug angiogenesis assay, a developmental retinal model and tumour models in mice were used. The mechanisms underlying TAT-ANK activity were investigated by immunochemistry, western blotting, immunoprecipitation, RT-qPCR and luciferase reporter assays.

KEY RESULTS

The amino acid residues 179-191 in the G-protein-coupled receptor-kinase-interacting protein-1 (GIT1-ankyrin domain) are crucial for GIT1 binding to the Notch transcription repressor, RBP-J. We designed the peptide TAT-ANK, based on residues 179-191 in GIT1. TAT-ANK significantly inhibited Dll4 expression and Notch 1 activation in HUVECs by competing with activated Notch1 to bind to RBP-J. The analyses of biological functions showed that TAT-ANK promoted angiogenesis in vitro and in vivo by inhibiting Dll4-Notch1 signalling.

CONCLUSIONS AND IMPLICATIONS

We synthesized and investigated the biological actions of TAT-ANK peptide, a new inhibitor of Notch signalling. This peptide will be of significant interest to research on Dll4-Notch1 signalling and to clinicians carrying out clinical trials using Notch signalling inhibitors. Furthermore, our findings will have important conceptual and therapeutic implications for angiogenesis-related diseases.

Notch signaling pathway: architecture, disease, and therapeutics

The NOTCH gene was identified approximately 110 years ago. Classical studies have revealed that NOTCH signaling is an evolutionarily conserved pathway. NOTCH receptors undergo three cleavages and translocate into the nucleus to regulate the transcription of target genes. NOTCH signaling deeply participates in the development and homeostasis of multiple tissues and organs, the aberration of which results in cancerous and noncancerous diseases. However, recent studies indicate that the outcomes of NOTCH signaling are changeable and highly dependent on context. In terms of cancers, NOTCH signaling can both promote and inhibit tumor development in various types of cancer. The overall performance of NOTCH-targeted therapies in clinical trials has failed to meet expectations. Additionally, NOTCH mutation has been proposed as a predictive biomarker for immune checkpoint blockade therapy in many cancers. Collectively, the NOTCH pathway needs to be integrally assessed with new perspectives to inspire discoveries and applications. In this review, we focus on both classical and the latest findings related to NOTCH signaling to illustrate the history, architecture, regulatory mechanisms, contributions to physiological development, related diseases, and therapeutic applications of the NOTCH pathway. The contributions of NOTCH signaling to the tumor immune microenvironment and cancer immunotherapy are also highlighted. We hope this review will help not only beginners but also experts to systematically and thoroughly understand the NOTCH signaling pathway.

Intrinsic and Extrinsic Factors Impacting Cancer Stemness and Tumor Progression

Tumor heterogeneity represents an important limitation to the development of effective cancer therapies. The presence of cancer stem cells (CSCs) and their differentiation hierarchies contribute to cancer complexity and confer tumors the ability to grow, resist treatment, survive unfavorable conditions, and invade neighboring and distant tissues. A large body of research is currently focusing on understanding the properties of CSCs, including their cellular and molecular origin, as well as their biological behavior in different tumor types. In turn, this knowledge informs strategies for targeting these tumor initiating cells and related cancer stemness. Cancer stemness is modulated by the tumor microenvironment, which influences CSC function and survival. Several advanced in vitro models are currently being developed to study cancer stemness in order to advance new knowledge of the key molecular pathways involved in CSC self-renewal and dormancy, as well as to mimic the complexity of patients' tumors in pre-clinical drug testing. In this review, we discuss CSCs and the modulation of cancer stemness by the tumor microenvironment, stemness factors and signaling pathways. In addition, we introduce current models that allow the study of CSCs for the development of new targeted therapies.

RASSF1A disrupts the NOTCH signaling axis via SNURF/RNF4-mediated ubiquitination of HES1

RASSF1A promoter methylation has been correlated with tumor dedifferentiation and aggressive oncogenic behavior. Nevertheless, the underlying mechanism of RASSF1A-dependent tumor dedifferentiation remains elusive. Here, we show that RASSF1A directly uncouples the NOTCH-HES1 axis, a key suppressor of differentiation. Interestingly, the crosstalk of RASSF1A with HES1 occurs independently from the signaling route connecting RASSF1A with the Hippo pathway. At the molecular level, we demonstrate that RASSF1A acts as a scaffold essential for the SUMO-targeted E3 ligase SNURF/RNF4 to target HES1 for degradation. The reciprocal relationship between RASSF1A and HES1 is evident across a wide range of human tumors, highlighting the clinical significance of the identified pathway. We show that HES1 upregulation in a RASSF1A-depleted environment renders cells non-responsive to the downstream effects of γ-secretase inhibitors (GSIs) which restrict signaling at the level of the NOTCH receptor. Taken together, we report a mechanism through which RASSF1A exerts autonomous regulation of the critical Notch effector HES1, thus classifying RASSF1A expression as an integral determinant of the clinical effectiveness of Notch inhibitors.

Identification, Culture and Targeting of Cancer Stem Cells

Chemoresistance, tumor progression, and metastasis are features that are frequently seen in cancer that have been associated with cancer stem cells (CSCs). These cells are a promising target in the future of cancer therapy but remain largely unknown. Deregulation of pathways that govern stemness in non-tumorigenic stem cells (SCs), such as Notch, Wnt, and Hedgehog pathways, has been described in CSC pathogenesis, but it is necessary to conduct further studies to discover potential new therapeutic targets. In addition, some markers for the identification and characterization of CSCs have been suggested, but the search for specific CSC markers in many cancer types is still under development. In addition, methods for CSC cultivation are also under development, with great heterogeneity existing in the protocols used. This review focuses on the most recent aspects of the identification, characterization, cultivation, and targeting of human CSCs, highlighting the advances achieved in the clinical implementation of therapies targeting CSCs and remarking those potential areas where more research is still required.

Nanoparticle-Based RNAi Therapeutics Targeting Cancer Stem Cells: Update and Prospective

Cancer stem cells (CSCs) are characterized by intrinsic self-renewal and tumorigenic properties, and play important roles in tumor initiation, progression, and resistance to diverse forms of anticancer therapy. Accordingly, targeting signaling pathways that are critical for CSC maintenance and biofunctions, including the Wnt, Notch, Hippo, and Hedgehog signaling cascades, remains a promising therapeutic strategy in multiple cancer types. Furthermore, advances in various cancer omics approaches have largely increased our knowledge of the molecular basis of CSCs, and provided numerous novel targets for anticancer therapy. However, the majority of recently identified targets remain ‘undruggable’ through small-molecule agents, whereas the implications of exogenous RNA interference (RNAi, including siRNA and miRNA) may make it possible to translate our knowledge into therapeutics in a timely manner. With the recent advances of nanomedicine, in vivo delivery of RNAi using elaborate nanoparticles can potently overcome the intrinsic limitations of RNAi alone, as it is rapidly degraded and has unpredictable off-target side effects. Herein, we present an update on the development of RNAi-delivering nanoplatforms in CSC-targeted anticancer therapy and discuss their potential implications in clinical trials.

Chemical Genetic Screen in Drosophila Germline Uncovers Small Molecule Drugs That Sensitize Stem Cells to Insult-Induced Apoptosis

Cancer stem cells, in contrast to their more differentiated daughter cells, can endure genotoxic insults, escape apoptosis, and cause tumor recurrence. Understanding how normal adult stem cells survive and go to quiescence may help identify druggable pathways that cancer stem cells have co-opted. In this study, we utilize a genetically tractable model for stem cell survival in the Drosophila gonad to screen drug candidates and probe chemical-genetic interactions. Our study employs three levels of small molecule screening: (1) a medium-throughput primary screen in male germline stem cells (GSCs), (2) a secondary screen with irradiation and protein-constrained food in female GSCs, and (3) a tertiary screen in breast cancer organoids in vitro. Herein, we uncover a series of small molecule drug candidates that may sensitize cancer stem cells to apoptosis. Further, we have assessed these small molecules for chemical-genetic interactions in the germline and identified the NF-κB pathway as an essential and druggable pathway in GSC quiescence and viability. Our study demonstrates the power of the Drosophila stem cell niche as a model system for targeted drug discovery.

Targeting Notch to Maximize Chemotherapeutic Benefits: Rationale, Advanced Strategies, and Future Perspectives

Simple Summary

The Notch signaling pathway regulates cell proliferation, apoptosis, stem cell self-renewal, and differentiation in a context-dependent fashion both during embryonic development and in adult tissue homeostasis. Consistent with its pleiotropic physiological role, unproper activation of the signaling promotes or counteracts tumor pathogenesis and therapy response in distinct tissues. In the last twenty years, a wide number of studies have highlighted the anti-cancer potential of Notch-modulating agents as single treatment and in combination with the existent therapies. However, most of these strategies have failed in the clinical exploration due to dose-limiting toxicity and low efficacy, encouraging the development of novel agents and the design of more appropriate combinations between Notch signaling inhibitors and chemotherapeutic drugs with improved safety and effectiveness for distinct types of cancer.

Abstract

Notch signaling guides cell fate decisions by affecting proliferation, apoptosis, stem cell self-renewal, and differentiation depending on cell and tissue context. Given its multifaceted function during tissue development, both overactivation and loss of Notch signaling have been linked to tumorigenesis in ways that are either oncogenic or oncosuppressive, but always context-dependent. Notch signaling is critical for several mechanisms of chemoresistance including cancer stem cell maintenance, epithelial-mesenchymal transition, tumor-stroma interaction, and malignant neovascularization that makes its targeting an appealing strategy against tumor growth and recurrence. During the last decades, numerous Notch-interfering agents have been developed, and the abundant preclinical evidence has been transformed in orphan drug approval for few rare diseases. However, the majority of Notch-dependent malignancies remain untargeted, even if the application of Notch inhibitors alone or in combination with common chemotherapeutic drugs is being evaluated in clinical trials. The modest clinical success of current Notch-targeting strategies is mostly due to their limited efficacy and severe on-target toxicity in Notch-controlled healthy tissues. Here, we review the available preclinical and clinical evidence on combinatorial treatment between different Notch signaling inhibitors and existent chemotherapeutic drugs, providing a comprehensive picture of molecular mechanisms explaining the potential or lacking success of these combinations.

Epithelial to Mesenchymal Transition in Patients with Pancreatic Ductal Adenocarcinoma: State-of-the-Art and Therapeutic Opportunities

Pancreatic ductal adenocarcinoma (PDAC) is one of the malignancies with the worst prognosis despite a decade of efforts. Up to eighty percent of patients are managed at late stages with metastatic disease, in part due to a lack of diagnosis. The effectiveness of PDAC therapies is challenged by the early and widespread metastasis. Epithelial to mesenchymal transition (EMT) is a major driver of cancer progression and metastasis. This process allows cancer cells to gain invasive properties by switching their phenotype from epithelial to mesenchymal. The importance of EMT has been largely described in PDAC, and its importance is notably highlighted by the two major subtypes found in PDAC: the classical epithelial and the quasi-mesenchymal subtypes. Quasi-mesenchymal subtypes have been associated with a poorer prognosis. EMT has also been associated with resistance to treatments such as chemotherapy and immunotherapy. EMT is associated with several key molecular markers both epithelial and mesenchymal. Those markers might be helpful as a biomarker in PDAC diagnosis. EMT might becoming a key new target of interest for the treatment PDAC. In this review, we describe the role of EMT in PDAC, its contribution in diagnosis, in the orientation and treatment follow-up. We also discuss the putative role of EMT as a new therapeutic target in the management of PDAC.