Targeting Notch Signaling Research Articles

DDDR-12. INHIBITION OF NOTCH PATHWAY VIA A NOVEL MONOCLONAL ANTIBODY PROLONGS SURVIVAL IN HIGH GRADE GLIOMA MODELS

Abstract High grade gliomas (HGGs) have poor prognosis partially owing to a glioma-stem cell (GSC) population that escapes most therapeutic modalities. Inhibition of NOTCH signaling, necessary for GSC maintenance, has shown promise, however clinically limited by systemic (on-target, off-tumor) side effects. Thus, we develop a novel monoclonal antibody, 1H5, inhibitory against a disintegrin and metalloproteinase 10 (ADAM10), a protein responsible for NOTCH signaling initiation in tumor tissue, to treat HGGs. Patient-derived, glioma cell lines were treated with 1H5 to determine therapeutic IC50 and characterize downstream, NOTCH-related effectors. A patient-derived explant system, which best replicates the tumor microenvironment in vitro, was generated and treated. An orthotopic xenograft model (PDX) of HGG was created and treated with convection enhanced delivery (CED) of 1H5 to assess tumor volume and survival. We determined that ADAM10 is found in a majority of IDH-wildtype HGGs, but not on IDH-mutant HGGs or low-grade gliomas. 1H5 has nanomolar IC50 against a large library of HGG patient-derived cell lines, achieving cell death via NOTCH-signaling inhibition. In explants, treatment with 1H5 significant delays explant progression (p = 0.01), expansion (4.1-fold decrease, p = 0.007), and reduces the fraction of ADAM10+ cells (from 63.3% to 2.6%, p = 0.004), of replicating cells (from 10.0% to 0.9%, p = 0.006), and of GSCs (SOX2+ cells; from 65.8% to 12.8%, p = 0.06). In vivo, CED of 1H5 both slows down tumor growth compared to vehicle-treated controls (2.2-fold decrease in tumor volume, p = 0.03), and significantly prolongs survival (p = 0.01), without the development of significant side effects, through a reduction of replicating cells (p = 0.01) and SOX2+ GSCs (p < 0.0001), in a dose-dependent fashion. In conclusion, 1H5 is efficacious against HGG preclinical models both in vitro and in vivo by targeting NOTCH signaling. This posits 1H5 as a new promising therapeutic worthy of expeditious clinical translation.

Decreased number of satellite cells-derived myonuclei in both fast- and slow-twitch muscles in HeyL-KO mice during voluntary running exercise

BackgroundSkeletal muscles possess unique abilities known as adaptation or plasticity. When exposed to external stimuli, such as mechanical loading, both myofiber size and myonuclear number increase. Muscle stem cells, also known as muscle satellite cells (MuSCs), play vital roles in these changes. HeyL, a direct target of Notch signaling, is crucial for efficient muscle hypertrophy because it ensures MuSC proliferation in surgically overloaded muscles by inhibiting the premature differentiation. However, it remains unclear whether HeyL is essential for MuSC expansion in physiologically exercised muscles. Additionally, the influence of myofiber type on the requirement for HeyL in MuSCs within exercised muscles remains unclear.MethodsWe used a voluntary wheel running model and HeyL-knockout mice to investigate the impact of HeyL deficiency on MuSC-derived myonuclei, MuSC behavior, muscle weight, myofiber size, and myofiber type in the running mice.ResultsThe number of new MuSC-derived myonuclei was significantly lower in both slow-twitch soleus and fast-twitch plantaris muscles from exercised HeyL-knockout mice than in control mice. However, expect for the frequency of Type IIb myofiber in plantaris muscle, exercised HeyL-knockout mice exhibited similar responses to control mice regarding myofiber size and type.ConclusionsHeyL expression is crucial for MuSC expansion during physiological exercise in both slow and fast muscles. The frequency of Type IIb myofiber in plantaris muscle of HeyL-knockout mice was not significantly reduced compared to that of control mice. However, the absence of HeyL did not affect the increased size and frequency of Type IIa myofiber in plantaris muscles. In this model, no detectable changes in myofiber size or type were observed in the soleus muscles of either control or HeyL-knockout mice. These findings imply that the requirement for MuSCs in the wheel-running model is difficult to observe due to the relatively low degree of hypertrophy compared to surgically overloaded models.

Synergistic Effects of Ethanol Extract of Allium sativum (Garlic) with DAPT and ATRA on Notch Signaling Targeted Molecular Action on Lung Cancer Cell line (A549)

Background: The activated oncogenic Notch signalling is an emerging target to treat cancer progression and recurrence. Synthetic inhibitors of Notch receptors are in pre-clinical studies. However, the overexpression of Notch signalling molecules at the gene level needs to be regulated to control cancer progression. Objective: We propose that this can be achieved by gene-regulatory drugs in combination with natural phytochemical compounds. Methods: The ethanol extract of Allium sativum alone and in combination with DAPT and ATRA were evaluated for cytotoxicity on A549 cells by MTT and Trypan blue assays. Their effects on Notch 1, Hes 1 and p53 gene expressions were studied by RT-PCR and qPCR. Their inhibition on metastatic invasion of A549 cells was analyzed by in vitro wound scratch assay. The phytochemicals of the extract were identified by GC-MS analysis. Results: Many organosulfur compounds having anti-cancer potency were identified in GC-MS. The combination treatment with 50μg (IC50) of garlic extract exhibited a highly significant (P≤0.01) synergistic inhibitory effect on A549 cell growth and migration. It has also significantly reduced the expression of Notch 1 and Hes 1 oncogenes and enhanced p53 gene expression, compared with the individual treatments. This indicates the synergistic action of the extract on the downregulation of Notch signalling at the mRNA level. Conclusion: Our study results imply that the combination therapies have potent molecular treatment action via down-regulating Notch signaling target genes and upregulating p53 gene expression as an underlying mechanism of inhibitory action on A549 lung cancer cells.

Notch-Dependent Expression of the Drosophila Hey Gene Is Supported by a Pair of Enhancers with Overlapping Activities.

Drosophila Hey is a basic helix-loop-helix-orange (bHLH-O) protein with an important role in the establishment of distinct identities of postmitotic cells. We have previously identified Hey as a transcriptional target and effector of Notch signalling during the asymmetric division of neuronal progenitors, generating neurons of two types, and we have shown that Notch-dependent expression of Hey also marks a subpopulation of the newborn enteroendocrine (EE) cells in the midgut primordium of the embryo. Here, we investigate the transcriptional regulation of Hey in neuronal and intestinal tissues. We isolated two genomic regions upstream of the promoter (HeyUP) and in the second intron (HeyIN2) of the Hey gene, based on the presence of binding motifs for Su(H), the transcription factor that mediates Notch activity. We found that both regions can direct the overlapping expression patterns of reporter transgenes recapitulating endogenous Hey expression. Moreover, we showed that while HeyIN2 represents a Notch-dependent enhancer, HeyUP confers both Notch-dependent and independent transcriptional regulation. We induced mutations that removed the Su(H) binding motifs in either region and then studied the enhancer functionality in the respective Hey mutant lines. Our results provide direct evidence that although both enhancers support Notch-dependent regulation of the Hey gene, their role is redundant, as a Hey loss-of-function lethal phenotype is observed only after deletion of all their Su(H) binding motifs by CRISPR/Cas9.

Notch signaling regulates UNC5B to suppress endothelial proliferation, migration, junction activity, and retinal plexus branching

Notch signaling guides vascular development and function by regulating diverse endothelial cell behaviors, including migration, proliferation, vascular density, endothelial junctions, and polarization in response to flow. Notch proteins form transcriptional activation complexes that regulate endothelial gene expression, but few of the downstream effectors that enable these phenotypic changes have been characterized in endothelial cells, limiting our understanding of vascular Notch activities. Using an unbiased screen of translated mRNA rapidly regulated by Notch signaling, we identified novel in vivo targets of Notch signaling in neonatal mouse brain endothelium, including UNC5B, a member of the netrin family of angiogenic-regulatory receptors. Endothelial Notch signaling rapidly upregulates UNC5B in multiple endothelial cell types. Loss or gain of UNC5B recapitulated specific Notch-regulated phenotypes. UNC5B expression inhibited endothelial migration and proliferation and was required for stabilization of endothelial junctions in response to shear stress. Loss of UNC5B partially or wholly blocked the ability of Notch activation to regulate these endothelial cell behaviors. In the developing mouse retina, endothelial-specific loss of UNC5B led to excessive vascularization, including increased vascular outgrowth, density, and branchpoint count. These data indicate that Notch signaling upregulates UNC5B as an effector protein to control specific endothelial cell behaviors and inhibit angiogenic growth.

Gasdermin D silencing alleviates airway inflammation and remodeling in an ovalbumin-induced asthmatic mouse model

Emerging evidence demonstrates that pyroptosis has been implicated in the pathogenesis of asthma. Gasdermin D (GSDMD) is the pyroptosis executioner. The mechanism of GSDMD in asthma remains unclear. The aim of this study was to elucidate the potential role of GSDMD in asthmatic airway inflammation and remodeling. Immunofluorescence staining was conducted on airway epithelial tissues obtained from both asthma patients and healthy controls (HCs) to evaluate the expression level of N-GSDMD. ELISA was used to measure concentrations of cytokines (IL-1β, IL-18, IL-17A, and IL-10) in serum samples collected from asthma patients and healthy individuals. We demonstrated that N-GSDMD, IL-18, and IL-1β were significantly increased in samples with mild asthma compared with those from the controls. Then, wild type and Gsdmd-knockout (Gsdmd−/−) mice were used to establish asthma model. We performed histopathological staining, ELISA, and flow cytometry to explore the function of GSDMD in allergic airway inflammation and tissue remodeling in vivo. We observed that the expression of N-GSDMD, IL-18, and IL-1β was enhanced in OVA-induced asthma mouse model. Gsdmd knockout resulted in attenuated IL-18, and IL-1β production in both bronchoalveolar lavage fluid (BALF) and lung tissue in asthmatic mice. In addition, Gsdmd−/− mice exhibit a significant reduction in airway inflammation and remodeling, which might be associated with reduced Th17 inflammatory response and M2 polarization of macrophages. Further, we found that GSDMD knockout may improve asthmatic airway inflammation and remodeling through regulating macrophage adhesion, migration, and macrophage M2 polarization by targeting Notch signaling pathway. These findings demonstrate that GSDMD deficiency profoundly alleviates allergic inflammation and tissue remodeling. Therefore, GSDMD may serve as a potential therapeutic target against asthma.

Cardiomyocyte Notch1 signaling is essential for protection of the maternal heart from peripartum stress

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft Background Peripartum cardiomyopathy (PPCM) is a life-threatening disease in women without known cardiovascular disease and is characterized by a sudden onset of heart failure (HF) before, under or after delivery. Previous studies suggest impaired endothelial to cardiomyocyte crosstalk as a major pathomechanism of the disease. Purpose Analyses of the role of Notch1 signaling for the endothelial-cardiomyocyte crosstalk in PPCM. Methods and results Serum from PPCM patients with acute HF reduced Notch1 expression in induced pluripotent stem cell derived cardiomyocytes (-20%, P<0.05) compared to serum from postpartum-matched healthy controls (PP-Ctrl). Beside miRNA-146a previously described to be up-regulated in PPCM plasma (6.8-fold, P<0.01), additional miRNAs targeting Notch1 signaling (miR-30a-3p, miR-34a, miR-200b-3p, miR-200c-3p, miR-429-3p, miR-449a) were up-regulated in PPCM plasma. Overexpression of these miRNAs in cardiomyocytes (CM) reduces Notch1 protein levels. Mice with a CM-restricted knockout of Notch1 (N1-KO) are born at the expected Mendelian ratio and nulli pari (NP) N1-KO female mice do not show a distinct cardiac phenotype at the age of 3 to 4 months compared to WT female mice (%FS WT: 41±5 vs N1-KO: 37±6; n= 9-12). However, they develop mild HF at the age of 6 months (%FS WT: 44±4 vs N1-KO: 31±8; n=11-14; P<0.01). Mated N1-KO females displayed normal cardiac function and LV dimensions in the last week of the first pregnancy. After 3 pregnancies and nursing periods, N1-KO developed severe HF (%FS WT PP: 30±5 vs N1-KO PP: 16±5; n=8-12; P<0.01), and show enhanced mortality (P<0.01). N1-KO-NP and N1-KO-PP displayed significant increase in the cardiac expression of the stress markers ANP and BNP compared to respective WT-NP and WT-PP. RNA-Seq analysis of N1-KO-PP revealed 1380 transcripts (adj. P<0.01) differently regulated genes, among them down-regulation of ErbB4, a known driver in PPCM onset. SiRNA-mediated knockdown of Notch1 in CM were associated with a decrease in ErbB4 protein expression. Treatment with bromocriptin (BR) was not able to improve survival and to rescue cardiac function and LV dimensions in postpartum N1-KO females (WT: 37±4, N1-KO: 23±10; n=7-8). Moreover, RNA-Seq analysis revealed that BR had no effect on the dysregulated cardiac mRNA. In conclusion, the pathophysiology of PPCM is associated with reduced cardiac Notch1 expression, which results in part from 16-kDa-prolactin mediated upregulation of miRNAs targeting Notch1. The reduced cardiac Notch1 expression contributes to PPCM as indicated with severe postpartum HF and high mortality in N1-KO mice. Inhibition of prolactin secretion with BR failed to rescue the development of PPCM in N1-KO mice suggesting that deregulated Notch1 is downstream of the 16-kDa prolactin-miRNA pathophysiology.

Notch1 signaling regulates Sox9 and VEGFA expression and governs BMP2-induced endochondral ossification of mesenchymal stem cells

Although bone morphogenetic protein 2 (BMP2) can induce chondrogenic differentiation of mesenchymal stem cells (MSCs), its induction of endochondral ossification limits the application of BMP2-based cartilage regeneration. Here, we clarified the mechanisms of BMP2-induced endochondral ossification of MSCs. In vitro and in vivo chondrogenic, osteogenic, and angiogenic differentiation models of MSCs were constructed. The expression of target genes was identified at both protein and mRNA levels. RNA sequencing, molecular docking, co-immunoprecipitation, and chromatin immunoprecipitation followed by sequencing were applied to investigate the molecular mechanisms. We found that BMP2 up-regulated the expression of Notch receptors and ligands in MSCs. Notch1 signaling activation was related to inhibition of chondrogenic differentiation, promotion of osteogenic and angiogenic differentiation. In vivo ectopic stem cell implantation identified that Notch1 signaling activation blocked BMP2-induced chondrogenesis and facilitated endochondral ossification of MSCs. Mechanistically, we elucidated Notch1 intracellular domain (NICD1)-RBPjk complex binding to SRY-box transcription factor 9 (Sox9) and vascular endothelial growth factor A (VEGFA) promoters to decrease Sox9 expression and increase VEGFA expression. These findings suggest that Notch1 signaling can regulate BMP2-induced endochondral ossification by promoting RBPjk-mediated Sox9 inactivation and VEGFA expression. It is conceivable that targeting Notch1 signaling mediated endochondral ossification would benefit BMP2-based cartilage regeneration.

A study to investigate the anticancer potential of carvacrol via targeting Notch signaling in breast cancer

Abstract Breast cancer (BC) continues to be a primary worldwide health concern despite the tremendous efforts made to deploy novel chemotherapeutic techniques for the treatment of BC. It is, therefore, essential to elucidate better plant-based compounds targeting deregulated signaling components in various cancer cell types. Our objective was to elucidate a potent targeted therapeutic approach by exploiting the anticancerous potential of carvacrol in MDA-MB-231 cells via employing silicon and in vitro approaches. In silico analysis was executed to identify the anticancer potential of carvacrol against BC via targeting crucial signaling component of the NOTCH pathway, namely Jagged-1 and its downstream target cyclin D1. In vitro, assays were also employed to display the antiproliferative potential of carvacrol at the mRNA level in MDA-MB-231 cells via targeting Jagged-1 and cyclin D1 genes. Docking studies using CB DOCK displayed better binding energy of carvacrol (Jagged-1: −5.0 and cyclin D1: −5.8) in comparison to the standard drug, 5-fluorouracil (Jagged-1: −4.5; cyclin D1: −4.6) against these crucial targets. Carvacrol potentially downregulated the expression of these crucial genes along with caspase-mediated apoptosis induction. However, more in vitro assays must be employed to validate its candidature for drug development against BC. This study provided a novel insight into the targeted therapeutic approach using natural products and deregulated signaling components for managing breast carcinoma.

Abstract 4463: Metabolic reprogramming through Notch1 signaling promotes a survival advantage in pancreatic neuroendocrine tumor cells

Abstract Background: Cancer cells utilize both oxidative phosphorylation (OXPHOS) and glycolysis to generate energy. Switching between OXPHOS and glycolysis can promote tumor progression. The mechanisms governing oncogenic metabolic reprogramming are largely unknown, but recent data has suggested that Notch1 dysregulation in cancer cells can contribute to altered metabolic phenotypes. We hypothesized that Notch1 signaling supports metabolic reprogramming in pancreatic neuroendocrine tumor (pNET) cells. Methods: We established a Notch1-knockout pNET cell line (BON-N1-KO) by deleting Notch1 at exon 3 in a pNET cell line (BON) using CRISPR/Cas9. Proliferation over time was measured using a trypan blue exclusion test. Seahorse Glycolytic Rate Assay and Mitochondria Stress Test were used to measure the glycolytic and mitochondrial activities of cells. A glycolysis deprivation assay was employed to determine cell viability at varying glucose concentrations. Single end RNAseq was performed using the Illumina NGS platform, to a read depth of 50M. Results: Over time, pNET cells lacking Notch1 (BON-N1-KO) proliferated slower than wildtype (WT) cells (p=0.034). Compared to WT BON, the BON-N1-KO cells had reduced basal oxygen consumption rate (28.2 ± 1.3 vs. 40.7 ± 1.4; p=0.02, ATP production (21.9 ± 1.0 vs. 29.6 ± 0.98; p=0.04), and maximal respiration (39.4 ± 1.7 vs. 63.7 ± 2.1; p=0.004). BON-N1-KO cells also had a reduction in basal glycolysis, as measured by proton efflux rate, compared to WT (48.7 ± 2.6 vs. 57.7 ± 6.2; p=0.2). To further test metabolic reprogramming, WT and BON-N1-KO cells were starved of glucose (0mM), compared to normal glucose (17.5mM) and viability was measured over time. By day 5, the BON-N1-KO group had a viability of 0%, whereas 12.8% of WT cells were alive (p=0.038). To determine if Notch1 loss was associated with altered expression of established metabolic genes, we performed RNAseq. Differential gene expression analysis found that OXPHOS-related genes (UQCC2, COX15, COX20) and glycolysis-related genes (Slc1a1, Slc2a4, Hk1, Hk2) were significantly down-regulated in BON-N1-KO cells. Conclusions: Our study shows that Notch1 signaling facilitates metabolic reprogramming as a survival advantage in pNET cells. Targeting Notch1 signaling to mediate cellular metabolism may be a novel therapeutic strategy in pNETs. Citation Format: Rachael Guenter, Weisheng Chen, Brendon Herring, Yuvasri Golivi, Melissa Sammy, Jason Whitt, Renata Jaskula-Sztul, Herbert Chen, J. Bart Rose. Metabolic reprogramming through Notch1 signaling promotes a survival advantage in pancreatic neuroendocrine tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4463.

Identifications of three novel alleles of Serrate in Drosophila

The Notch signaling pathway, an evolutionarily highly conserved pathway, participates in various essential physiological processes in organisms. Activation of Notch signaling in the canonical manner requires the combination of ligand and receptor. There are two ligands of Notch in Drosophila: Delta (Dl) and Serrate (Ser). A mutation mf157 is identified for causing nicks of fly wings in genetic analysis from a mutant library (unpublished) that was established previously. Immunofluorescent staining illustrates that mf157 represses the expression of Cut and Wingless (Wg), the targets of Notch signaling. MARCM cloning analysis reveals that mf157 functions at the same level or the upstream of ligands of Notch in signaling sending cells. Sequencing demonstrates that mf157 is a novel allele of the Ser gene. Subsequently, mf553 and mf167 are also identified as new alleles of Ser from our library. Furthermore, the complementary assays and the examination of transcripts confirm the sequencing results. Besides, the repressed phenotypes of Notch signaling were reverted by transposon excision experiments of mf157. In conclusion, we identify three fresh alleles of Ser. Our works supply additional genetic resources for further study of functions of Ser and Notch signaling regulation.

Targeting Notch signaling pathways with natural bioactive compounds: a promising approach against cancer.

Notch signaling pathway is activated abnormally in solid and hematological tumors, which perform essential functions in cell differentiation, survival, proliferation, and angiogenesis. The activation of Notch signaling and communication among Notch and other oncogenic pathways heighten malignancy aggressiveness. Thus, targeting Notch signaling offers opportunities for improved survival and reduced disease incidence. Already, most attention has been given to its role in the cancer cells. Recent research shows that natural bioactive compounds can change signaling molecules that are linked to or interact with the Notch pathways. This suggests that there may be a link between Notch activation and the growth of tumors. Here, we sum up the natural bioactive compounds that possess inhibitory effects on human cancers by impeding the Notch pathway and preventing Notch crosstalk with other oncogenic pathways, which provoke further study of these natural products to derive rational therapeutic regimens for the treatment of cancer and develop novel anticancer drugs. This review revealed Notch as a highly challenging but promising target in oncology.

Directing cellular responses in a nanocomposite 3D matrix for tissue regeneration with nanoparticle-mediated drug delivery

Hydrogels play an important role in tissue engineering due to their native extracellular matrix-like characteristics, but they are insufficient in providing the necessary stimuli to support tissue formation. Efforts to integrate bioactive cues directly into hydrogels are hindered by incompatibility with hydrophobic drugs, issues of burst/uncontrolled release, and rapid degradation of the bioactive molecules. Skeletal muscle tissue repair requires internal stimuli and communication between cells for regeneration, and nanocomposite systems offer to improve the therapeutic effects in tissue regeneration. Here, the versatility of mesoporous silica nanoparticles (MSN) was leveraged to formulate a nanoparticle-hydrogel composite and to combine the benefits of controlled delivery of bioactive cues and cellular support. The tunable surface characteristics of MSNs were exploited to optimize homogeneity and intracellular drug delivery in a 3D matrix. Nanocomposite hydrogels formulated with acetylated or succinylated MSNs achieved high homogeneity in 3D distribution, with succinylated MSNs being rapidly internalized and acetylated MSNs exhibiting slower cellular uptake. MSN-hydrogel nanocomposites simultaneously allowed efficient local intracellular delivery of a hydrophobic model drug. To further study the efficiency of directing cell response, a Notch signaling inhibitor (DAPT) was incorporated into succinylated MSNs and incorporated into the hydrogel. MSN-hydrogel nanocomposites effectively downregulated the Notch signaling target genes, and accelerated and maintained the expression of myogenic markers. The current findings demonstrate a proof-of-concept in effective surface engineering strategies for MSN-based nanocomposites, suited for hydrophobic drug delivery in tissue regeneration with guided cues.

Extracellular Vesicle MicroRNAs From Corneal Stromal Stem Cell Enhance Stemness of Limbal Epithelial Stem Cells by Targeting the Notch Pathway.

The limbal niche supports the self-renewal of limbal epithelial stem cells (LESCs). The corneal stromal stem cell (CSSC) is an important component in the niche that regulates the LESC phenotype. However, the intercellular communication between LESCs and CSSCs has yet to be elucidated. A traditional two-dimensional (2D) system, a direct three-dimensional (3D) system, and an indirect 3D coculture system of LESCs and CSSCs were used to elucidate the paracrine pathway effect of CSSCs on LESCs. To reveal the impact of CSSC derived extracellular vesicles (CSSC-EVs) on LESCs, GW4869 and CSSC-EVs were added separately to the LESC culture medium. The outgrowth rate, cell density, differentiation, and stemness maintenance were compared among these methods. The miRNAs in the CSSC-EVs were sequenced, and the targeted Notch pathway was further confirmed by RT‒qPCR and Western blotting. Compared with 2D culture, both the direct and indirect 3D coculture systems yielded a higher outgrowth rate and expression of stem cell markers of LESCs. The phenotypes of LESCs cultivated using the two coculture approaches were also comparable. Nevertheless, GW4869 inhibited the effect of CSSCs on LESCs, and the addition of CSSC-EVs to the 2D culture system could increase cell density, and the proportion of p63αbright cells, which indicated that CSSC-EVs were crucial in regulating LESCs. Furthermore, the EV-AlixKD with reduced miRNA partly lost its regulating function. The abundant miRNAs in CSSC-EVs, such as hsa-miR-663b, hsa-miR-16-5p, and hsa-miR-1290, target the Notch pathway. The LESCs transfected with miR-663b had higher p63 expression via downregulating of the Notch pathway. CSSC-EV played an important role in promoting LESC proliferation and stemness maintenance by targeting Notch signaling via miRNAs, which will increase our understanding of the limbal niche and provide a potential new approach for LESC culture and the treatment of corneal epithelial disorders.

Loss of HES1 expression is associated with extracellular matrix remodeling and tumor immune suppression in KRAS mutant colon adenocarcinomas

The loss of HES1, a canonical Notch signaling target, may cooperate with KRAS mutations to remodel the extracellular matrix and to suppress the anti-tumor immune response. While HES1 expression is normal in benign hyperplastic polyps and normal colon tissue, HES1 expression is often lost in sessile serrated adenomas/polyps (SSAs/SSPs) and colorectal cancers (CRCs) such as those right-sided CRCs that commonly harbor BRAF or KRAS mutations. To develop a deeper understanding of interaction between KRAS and HES1 in colorectal carcinogenesis, we selected microsatellite stable (MSS) and KRAS mutant or KRAS wild type CRCs that show aberrant expression of HES1 by immunohistochemistry. By comparing the transcriptional landscapes of microsatellite stable (MSS) CRCs with or without nuclear HES1 expression, we investigated differentially expressed genes and activated pathways. We identified pathways and markers in the extracellular matrix and immune microenvironment that are associated with mutations in KRAS. We found that loss of HES1 expression positively correlated with matrix remodeling and epithelial-mesenchymal transition but negatively correlated with tumor cell proliferation. Furthermore, loss of HES1 expression in KRAS mutant CRCs correlates with a higher M2 macrophage polarization and activation of IL6 and IL10 immunosuppressive signature. Identifying these HES1-related markers may be useful for prognosis stratification and developing treatment for KRAS-mutant CRCs.

#3048 INDOXYL SULFATE INHIBITS OSTEOGENESIS OF BONE MARROW DERIVED MESENCHYMAL STEM CELLS THROUGH AHR/HES1/BMP2 PATHWAY

Abstract Background and Aims There is a high global burden of chronic kidney disease (CKD). The increased risk of bone fracture in patients with CKD suggests that CKD-associated factors, such as uremic toxins, might be the cause. Recent studies demonstrated that low turnover osteodystrophy and bone formation defect develop in early CKD, which indicates that uremic toxins, particularly in relatively low concentrations, can potentially be a cause. Thus far, studies about defected osteogenesis adopted high concentrations of uremic toxins (for example, indoxyl sulfate (ISx) >100 μM). Furthermore, the pathology is not yet fully investigated. Uremic toxin induced aryl hydrocarbon receptor (AHR) has been linked to bone formation defect, however, the mechanisms are incompletely understood. AHR inhibit osteogenesis during early processes of differentiation of early cells (stem cells), but whether uremic toxins induced AHR to affect stem cell in osteogenesis lineage has yet to be studied. The present study aims to clarify whether ISx at concentrations approximate to average in CKD patients (20 μM in free form) affect osteogenesis of bone marrow-derived mesenchymal stem cells (BMSCs), and further survey the underline signal transduction of AHR-induced defected osteogenesis. Method Mineralization of D1 cells (mouse BMSCs) was evaluated by alizarin red S staining (ARS). The mRNA expressions and protein levels of osteogenic markers including Runx2, BMP2, ALP, and osteocalcin were determined by quantitative real-time polymerase chain reaction (RT-PCR) and western blotting. AHR translocation into the nucleus was evaluated by an immunofluorescence confocal microscope. Reporter gene assays were adopted to study the transcriptional regulation of Runx2 and BMP2. Results ISx at concentrations ≤50 μM significantly downregulated mineralization of BMSCs with the most influence in the early stage of osteogenesis. ISx decreased the mRNA expressions and protein levels of osteogenic markers Runx2, BMP2, ALP, and osteocalcin. ISx of 50 μM induced AHR translocation into the nucleus and upregulated AHR target genes CYP1a1 and CYP1b1. The ISx-induced mineralization defects of BMSCs were counteracted by AHR antagonist CH223191, while downregulated gene expressions of osteogenic markers were recovered by AHR antagonist and knockdown (KD) of AHR. In mechanistic studies, ISx upregulated mRNA levels of hairy and enhancer of split (HES1), which is a primary target of NOTCH signaling. Although there were no significant differences in expressions of Notch1∼4, the upregulated Hes1 was attenuated by the antagonist and KD of AHR, which indicated that Hes1 was directly regulated by AHR. We identified putative binding sites of transcription repressor Hes1 in the promoter area of BMP2 and Runx2. Following experimental treatment of ISx, expression levels of BMP2 and Runx2 monitored by reporter assays were downregulated, which indicated that Hes1 plays as a transcription repressor to downregulated BMP2 and Runx2. Conclusion ISx under clinically relevant concentrations attenuated mineralization of BMSCs, particularly in the early stage of osteogenesis. ISx-induced AHR upregulated Hes1, which inhibited expressions of not only Runx2, but also BMP2, which has not been published before. A study of the underline signal transduction pathways relevant to the AHR genomic control system may provide potential therapy for low bone formation in early CKD.

γ-tocotrienol regulates gastric cancer by targeting notch signaling pathway

BackgroundGastric cancer is a common cause of death from cancer and an important global health care issue. Consequently, there is an urgent need to find new drugs and therapeutic targets for the treatment of gastric cancer. Recent studies have shown that tocotrienols (T3) have significant anticancer ability in cancer cell lines. Our previous study found that γ-tocotrienol (γ-T3) induced apoptosis in gastric cancer cells. We further explored the possible mechanisms of γ-T3 therapy for gastric cancer.MethodsIn this study, we treated gastric cancer cells with γ-T3, collect and deposit the cells. γ-T3-treated gastric cancer cells group and untreated group were subjected to RNA-seq assay, and analysis of sequencing results.ResultsConsistent with our previous findings, the results suggest that γ-T3 can inhibit mitochondrial complexes and oxidative phosphorylation. Analysis reveals that γ-T3 has altered mRNA and ncRNA in gastric cancer cells. Significantly altered signaling pathways after γ-T3 treatment were enriched for human papillomavirus infection (HPV) pathway and notch signaling pathway. The same significantly down-regulated genes notch1 and notch2 were present in both pathways in γ-T3-treated gastric cancer cells compared to controls.ConclusionsIt is indicated that γ-T3 may cure gastric cancer by inhibiting the notch signaling pathway. To provide a new and powerful basis for the clinical treatment of gastric cancer.

Cooperative NF-κB and Notch1 signaling promotes macrophage-mediated MenaINV expression in breast cancer

Metastasis is a multistep process that leads to the formation of clinically detectable tumor foci at distant organs and frequently to patient demise. Only a subpopulation of breast cancer cells within the primary tumor can disseminate systemically and cause metastasis. To disseminate, cancer cells must express MenaINV, an isoform of the actin regulatory protein Mena, encoded by the ENAH gene, that endows tumor cells with transendothelial migration activity, allowing them to enter and exit the blood circulation. We have previously demonstrated that MenaINV mRNA and protein expression is induced in cancer cells by macrophage contact. In this study, we discovered the precise mechanism by which macrophages induce MenaINV expression in tumor cells. We examined the promoter of the human and mouse ENAH gene and discovered a conserved NF-κB transcription factor binding site. Using live imaging of an NF-κB activity reporter and staining of fixed tissues from mouse and human breast cancer, we further determined that for maximal induction of MenaINV in cancer cells, NF-κB needs to cooperate with the Notch1 signaling pathway. Mechanistically, Notch1 signaling does not directly increase MenaINV expression, but it enhances and sustains NF-κB signaling through retention of p65, an NF-κB transcription factor, in the nucleus of tumor cells, leading to increased MenaINV expression. In mice, these signals are augmented following chemotherapy treatment and abrogated upon macrophage depletion. Targeting Notch1 signaling in vivo decreased NF-κB signaling activation and MenaINV expression in the primary tumor and decreased metastasis. Altogether, these data uncover mechanistic targets for blocking MenaINV induction that should be explored clinically to decrease cancer cell dissemination and improve survival of patients with metastatic disease.

Abstract 3598: Cooperative NF-KappaB and Notch1 signaling promotes a macrophage-mediated metastatic phenotype in breast cancer

Abstract Metastasis is a multistep process that leads to the formation of clinically detectable tumor foci at distant organs and, frequently, to patient demise. Only a subpopulation of breast cancer cells within the primary tumor can disseminate systemically and cause metastasis. To disseminate, cancer cells must express MenaINV, an isoform of the actin-regulatory protein, Mena, encoded by the ENAH gene that endows tumor cells with transendothelial migration activity allowing them to enter and exit the blood circulation. We have previously demonstrated that MenaINV mRNA and protein expression is induced in cancer cells by macrophage contact. Here, we report on the discovery of the precise mechanism by which macrophages induce MenaINV expression in tumor cells. We examined the promoter of the human and mouse ENAH gene and discovered a conserved NF-κB transcription factor binding site. Using live imaging of an NF-κB activity reporter and staining of fixed tissues from mouse and human breast cancer we further determined that, for maximal induction of MenaINV in cancer cells, NF-κB needs to cooperate with the Notch1 signaling pathway. Mechanistically, Notch1 signaling does not directly increase MenaINV expression, but instead enhances and sustains NF-κB signaling through retention of p65, an NF-κB transcription factor, in the nucleus of tumor cells, leading to increased MenaINV expression. In mice, these signals are augmented following chemotherapy treatment and abrogated upon macrophage depletion. Targeting Notch1 signaling in vivo decreased NF-κB signaling and MenaINV expression in the primary tumor and decreased metastasis. Altogether, these data uncover mechanistic targets for blocking MenaINV induction that should be explored clinically to decrease cancer cell dissemination and improve survival of patients with metastatic disease. Citation Format: Camille L. Duran, George S. Karagiannis, Xiaoming Chen, Ved P. Sharma, David Entenberg, John S. Condeelis, Maja H. Oktay. Cooperative NF-KappaB and Notch1 signaling promotes a macrophage-mediated metastatic phenotype in breast cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3598.

Abstract 2594: Alcohol drinking inhibits NOTCH-PAX9 signaling in esophageal squamous epithelial cells

Abstract Alcohol drinking has been established as a major risk factor for esophageal diseases, such as gastroesophageal reflux disease (GERD) and esophageal squamous cell carcinoma (ESCC). Certain mechanisms of alcohol-induced esophageal injury are supported by experimental data, whereas most are speculative or extrapolated from studies on cancers of other organ sites. Our previous study showed that ethanol exposure inhibited PAX9 expression in human esophageal squamous epithelial cells in vitro and in vivo, and promoted ESCC. In this study, we aimed to investigate the molecular pathways through which alcohol drinking suppresses PAX9 in esophageal squamous epithelial cells. Gene microarray, qRT-PCR, ChIP-PCR, Western blotting, and immunostaining were used to identify and validate inhibition of NOTCH-PAX9 signaling in human esophageal squamous epithelial cells and mouse esophagus after ethanol exposure. Human tissue samples were analyzed to further validate NOTCH inhibition by alcohol drinking. We first demonstrated the inhibition of NOTCH by ethanol exposure in vitro. NOTCH regulated PAX9 expression in esophageal squamous epithelial cells in vitro and in vivo. RBPJ and NOTCH intracellular domain (NICD1) ChIP-PCR confirmed Pax9 as a direct downstream target of NOTCH signaling in mouse esophagus. NOTCH inhibition by alcohol drinking was further validated in mouse esophagus and human tissue samples. In conclusion, ethanol exposure inhibited NOTCH signaling and thus suppressed PAX9 expression in esophageal squamous epithelial cells in vitro and in vivo. Our data support a novel mechanism of alcohol-induced esophageal injury through the inhibition of NOTCH-PAX9 signaling. As a result, chemical NOTCH activators may be used to prevent or treat alcohol-associated esophageal diseases such as GERD and ESCC. Citation Format: Zhaohui Xiong. Alcohol drinking inhibits NOTCH-PAX9 signaling in esophageal squamous epithelial cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2594.