Hypoxia preconditioning increases Notch1 activity by regulating DNA methylation in vitro and in vivo.

BACKGROUND: Our previous research has demonstrated that hypoxic preconditioning (HPC) can improve spatial learning and memory abilities in adult mice. Adult hippocampal neurogenesis has been associated with learning and memory. The Neurogenic locus notch homolog protein (Notch) was involved in adult hippocampal neurogenesis, as well as in learning and memory. It is currently unclear whether the Notch pathway regulates hippocampal neuroregeneration by modifying the DNA methylation status of the Notch gene following HPC. METHOD: The HPC animal model and cell model were established through repeated hypoxia exposure using mice and the mouse hippocampal neuronal cell line HT22. Step-down test was conducted on HPC mice. Real-time PCR and Western blot analysis were used to assess the mRNA and protein expression levels of Notch1 and hairy and enhancer of split1 (HES1). The presence of BrdU-positive cells and Notch1 expression in the hippocampal dental gyrus (DG) were examined with confocal microscopy. The methylation status of the Notch1 was analyzed using methylation-specific PCR (MS-PCR). HT22 cells were employed to elucidate the impact of HPC on Notch1 in vitro. RESULTS: HPC significantly improved the step-down test performance of mice with elevated levels of mRNA and protein expression of Notch1 and HES1 (P < 0.05). The intensities of the Notch1 signal in the control group, the H group and the HPC group were 2.62 ± 0.57 × 107, 2.87 ± 0.84 × 107, and 3.32 ± 0.14 × 107, respectively, and the number of BrdU (+) cells in the hippocampal DG were 1.83 ± 0.54, 3.71 ± 0.64, and 7.29 ± 0.68 respectively. Compared with that in C and H group, the intensity of the Notch1 signal and the number of BrdU (+) cells increased significantly in HPC group (P < 0.05). The methylation levels of the Notch1 promoter 0.82 ± 0.03, 0.65 ± 0.03, and 0.60 ± 0.02 in the C, H, and HPC groups, respectively. The methylation levels of Notch1 decreased significantly (P < 0.05). The effect of HPC on HT22 cells exhibited similarities to that observed in the hippocampus. CONCLUSION: HPC may confer neuroprotection by activating the Notch1 signaling pathway and regulating its methylation level, resulting in the regeneration of hippocampal neurons.

NOTCH1-Related Leukoencephalopathy: A Novel Variant and Literature Review.

NOTCH1-related leukoencephalopathy is a new diagnostic entity linked to heterozygous gain-of-function variants in NOTCH1 that neuroradiologically show some overlap with the inflammatory microangiopathy Aicardi-Goutières syndrome (AGS). To report a 16-year-old boy harbouring a novel NOTCH1 mutation who presented neuroradiological features suggestive of enhanced type I interferon signalling. We describe five years of follow-up and review the current literature on NOTCH1-related leukoencephalopathy. Clinical evaluation, standardised scales (SPRS, SARA, CBCL, CDI-2:P, WISCH-IV and VABS-2) and neuroradiological studies were performed, as well as blood DNA analysis. For the literature review, a search was performed on Pubmed, Scopus and Web of Science up to December 2023 using the following text word search strategy: (NOTCH1) AND (leukoencephalopathy). Our patient presents clinical features consistent with other reported cases with NOTCH1 mutations but is among the minority of patients with an onset after infancy. During the five-year follow-up, we observed an increase in the severity of spasticity and ataxia. However, at the age of 16 years, our proband is still ambulatory. As for other reported patients, he manifests psychiatric features ranging from hyperactivity during childhood to anxiety and depression during adolescence. The neuroradiological picture remained essentially stable over five years. In addition to the typical findings of leukoencephalopathy with cysts and calcifications already described, we report the presence of T2-hyperintensity and T1-hypotensity of the transverse pontine fibres, enhancement in the periventricular white matter after gadolinium administration and decreased NAA and Cho peaks in the periventricular white matter on MRS. We identified a novel heterozygous variant in NOTCH1 (c.4788_4799dup), a frame insertion located in extracellular negative regulatory region (NRR)-domain as in previously published cases. Blood interferon signalling was not elevated compared to controls. This case provides further data on a new diagnostic entity, i.e., NOTCH1-related leukoencephalopathy. By describing a standardised five-year follow-up in one case and reviewing the other patients described to date, we outline recommendations relating to monitoring in this illness, emphasising the importance of psychiatric and gastroenterological surveillance alongside neurological and neuropsychological management. Studies are needed to better understand the factors influencing disease onset and severity, which are heterogeneous.

Cis inhibition of NOTCH1 through JAGGED1 sustains embryonic hematopoietic stem cell fate.

Hematopoietic stem cells (HSCs) develop from the hemogenic endothelium (HE) in the aorta- gonads-and mesonephros (AGM) region and reside within Intra-aortic hematopoietic clusters (IAHC) along with hematopoietic progenitors (HPC). The signalling mechanisms that distinguish HSCs from HPCs are unknown. Notch signaling is essential for arterial specification, IAHC formation and HSC activity, but current studies on how Notch segregates these different fates are inconsistent. We now demonstrate that Notch activity is highest in a subset of, GFI1 + , HSC-primed HE cells, and is gradually lost with HSC maturation. We uncover that the HSC phenotype is maintained due to increasing levels of NOTCH1 and JAG1 interactions on the surface of the same cell (cis) that renders the NOTCH1 receptor from being activated. Forced activation of the NOTCH1 receptor in IAHC activates a hematopoietic differentiation program. Our results indicate that NOTCH1-JAG1 cis-inhibition preserves the HSC phenotype in the hematopoietic clusters of the embryonic aorta.

Involvement of NOTCH1-mediated Microglia Activation in Neuromodulation of Chronic Prostatitis-related Pain.

BACKGROUND/AIM: This study aimed to investigate the role of NOTCH receptor 1 (NOTCH1)-mediated activation of microglia in the L5-S2 spinal dorsal horn in chronic prostatitis pain. MATERIALS AND METHODS: Rats were divided into chronic prostatitis (CP) group and control group. Complete Freund's adjuvant was injected into the prostate, and prostate pathology and pain-related behavior were monitored to assess the successful establishment of the CP-related pain model. The dorsal horn of the L5-S2 spinal cord was collected for the detection of ionized calcium-binding adapter molecule 1 (IBA-1) and NOTCH1 expression by quantitative real time polymerase chain reaction and the detection of tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) by enzyme-linked immunosorbent assay. Electrical excitability was assessed with whole-cell patch clamp. In addition, NOTCH1 receptor inhibitor or inhibitor of microglial cell activation was injected into the subarachnoid space, and the pro-inflammatory cytokines in the spinal cord were detected. RESULTS: In the CP group, the expression of NOTCH1, IBA-1, TNF-α and IL-1ß began to increase at 4 days, peaked at 12 days, and began to decline at 24 days, and it was significantly higher than in the control group (p<0.01). Inhibition of microglia or NOTCH1 receptor markedly reduced the content of TNF-α and IL-1ß in the spinal cord (p<0.05). At 4, 12 and 24 days, the amplitude and frequency of neuronal action potential increased and the threshold decreased markedly as compared to the control group (p<0.05), and spontaneous action potential was noted. CONCLUSION: NOTCH1 mediates the activation of microglia in the L5-S2 spinal cord, leading to the secretion of inflammatory factors and enhanced electrical excitability of neurons, which is related to persistent and refractory chronic prostatitis-related pain.

[Resveratrol Inhibits T-acute Lymphoblastic Leukemia in Mice by Regulating Notch1 Signaling Pathway].

OBJECTIVE: To observe the effect of resveratrol (Res) on T-acute lymphoblastic leukemia (T-ALL) mice, and further explore its mechanism on Notch1 signaling pathway. METHODS: Twenty-five 6-8 weeks old female C57BL/6 mice were randomly divided into control group, T-ALL group and Res group. Res group was further divided into low-Res, middle-Res and high-Res group. The percentage of leukemia cells in peripheral blood and spleen cell suspension were detected by flow cytometry and Wright-Giemsa staining, pathological morphology of spleen and bone marrow tissues were observed by HE staining, the expression levels of Notch1, Hes-1, c-Myc, miR-19b and PTEN mRNA in spleen tissue were detected by RT-qPCR, and the protein levels of Notch1, Hes-1, c-Myc, p-PTEN and PTEN were detected by Western blot. RESULTS: Compared with control group, the leukemia cells in peripheral blood of mice in T-ALL group were markedly increased, accompanied by diffuse infiltration of leukemia cells in spleen and bone marrow tissues, the mRNA levels of Notch1, Hes-1, c-Myc, miR-19b and the protein levels of Notch1, Hes-1, c-Myc were increased (P <0.01), while the expression of PTEN mRNA and protein were significantly decreased in the spleen tissue of T-ALL mice (P <0.01). The above indicators in the H-Res group were reversed compared with T-ALL group after administration of resveratrol. CONCLUSION: Resveratrol may play a role in anti T-ALL by inhibiting Notch1 signaling pathway in mice.

ASPM stabilizes the NOTCH intracellular domain 1 and promotes oncogenesis by blocking FBXW7 binding in hepatocellular carcinoma cells.

Notch signaling is aberrantly activated in approximately 30% of hepatocellular carcinoma (HCC), significantly contributing to tumorigenesis and disease progression. Expression of the major Notch receptor, NOTCH1, is upregulated in HCC cells and correlates with advanced disease stages, although the molecular mechanisms underlying its overexpression remain unclear. Here, we report that expression of the intracellular domain of NOTCH1 (NICD1) is upregulated in HCC cells due to antagonism between the E3-ubiquitin ligase F-box/WD repeat-containing protein 7 (FBXW7) and the large scaffold protein abnormal spindle-like microcephaly-associated protein (ASPM) isoform 1 (ASPM-i1). Mechanistically, FBXW7-mediated polyubiquitination and the subsequent proteasomal degradation of NICD1 are hampered by the interaction of NICD1 with ASPM-i1, thereby stabilizing NICD1 and rendering HCC cells responsive to stimulation by Notch ligands. Consistently, downregulating ASPM-i1 expression reduced the protein abundance of NICD1 but not its FBXW7-binding-deficient mutant. Reinforcing the oncogenic function of this regulatory module, the forced expression of NICD1 significantly restored the tumorigenic potential of ASPM-i1-deficient HCC cells. Echoing these findings, NICD1 was found to be strongly co-expressed with ASPM-i1 in cancer cells in human HCC tissues (P < 0.001). In conclusion, our study identifies a novel Notch signaling regulatory mechanism mediated by protein-protein interaction between NICD1, FBXW7, and ASPM-i1 in HCC cells, representing a targetable vulnerability in human HCC.

N6-Methyladenosine Reader YTHDF1 Promotes Stemness and Therapeutic Resistance in Hepatocellular Carcinoma by Enhancing NOTCH1 Expression.

N6-methyladenosine (m6A) RNA modification is the most common and conserved epigenetic modification in mRNA and has been shown to play important roles in cancer biology. As the m6A reader YTHDF1 has been reported to promote progression of hepatocellular carcinoma (HCC), it represents a potential therapeutic target. In this study, we evaluated the clinical significance of YTHDF1 using human HCC samples and found that YTHDF1 was significantly upregulated in HCCs with high stemness scores and was positively associated with recurrence and poor prognosis. Analysis of HCC spheroids revealed that YTHDF1 was highly expressed in liver cancer stem cells (CSC). Stem cell-specific conditional Ythdf1 knockin (CKI) mice treated with diethylnitrosamine showed elevated tumor burden as compared with wild-type mice. YTHDF1 promoted CSCs renewal and resistance to the multiple tyrosine kinase inhibitors lenvatinib and sorafenib in patient-derived organoids and HCC cell lines, which could be abolished by catalytically inactive mutant YTHDF1. Multiomic analysis, including RNA immunoprecipitation sequencing, m6A methylated RNA immunoprecipitation sequencing, ribosome profiling, and RNA sequencing identified NOTCH1 as a direct downstream of YTHDF1. YTHDF1 bound to m6A modified NOTCH1 mRNA to enhance its stability and translation, which led to increased NOTCH1 target genes expression. NOTCH1 overexpression rescued HCC stemness in YTHDF1-deficient cells in vitro and in vivo. Lipid nanoparticles targeting YTHDF1 significantly enhanced the efficacy of lenvatinib and sorafenib in HCC in vivo. Taken together, YTHDF1 drives HCC stemness and drug resistance through an YTHDF1-m6A-NOTCH1 epitranscriptomic axis, and YTHDF1 is a potential therapeutic target for treating HCC. SIGNIFICANCE: Inhibition of YTHDF1 expression suppresses stemness of hepatocellular carcinoma cells and enhances sensitivity to targeted therapies, indicating that targeting YTHDF1 may be a promising therapeutic strategy for liver cancer.

Analysis of Notch1 protein expression in methotrexate-associated lymphoproliferative disorders.

Methotrexate (MTX)-associated lymphoproliferative disorder (MTX-LPD) is a lymphoproliferative disorder in patients treated with MTX. The mechanism of pathogenesis is still elusive, but it is thought to be a complex interplay of factors, such as underlying autoimmune disease activity, MTX use, Epstein-Barr virus infection, and aging. The NOTCH genes encode receptors for a signaling pathway that regulates various fundamental cellular processes, such as proliferation and differentiation during embryonic development. Mutations of NOTCH1 have been reported in B-cell tumors, including chronic lymphocytic leukemia/lymphoma, mantle cell lymphoma, and diffuse large B-cell lymphoma (DLBCL). Recently, it has also been reported that NOTCH1 mutations are found in post-transplant lymphoproliferative disorders, and in CD20-positive cells in angioimmunoblastic T-cell lymphoma, which might be associated with lymphomagenesis in immunodeficiency. In this study, to investigate the association of NOTCH1 in the pathogenesis of MTX-LPD, we evaluated protein expression of Notch1 in nuclei immunohistochemically in MTX-LPD cases [histologically DLBCL-type (n = 24) and classical Hodgkin lymphoma (CHL)-type (n = 24)] and de novo lymphoma cases [DLBCL (n = 19) and CHL (n = 15)]. The results showed that among MTX-LPD cases, the expression of Notch1 protein was significantly higher in the DLBCL type than in the CHL type (P < 0.001). In addition, among DLBCL morphology cases, expression of Notch1 tended to be higher in MTX-LPD than in the de novo group; however this difference was not significant (P = 0.0605). The results showed that NOTCH1 may be involved in the proliferation and tumorigenesis of B cells under the use of MTX. Further research, including genetic studies, is necessary.

NOTCH1-Induced T-Cell Acute Lymphoblastic Leukemia In Vivo Models.

T-cell acute lymphoblastic leukemia (T-ALL) is primarily a NOTCH1-driven disease, which represents approximately 15% of pediatric and 25% of adult newly diagnosed ALL cases. Gain-of-function NOTCH1 mutations are highly prevalent in T-ALL contributing to almost 60% of the cases. The protocol presented here describes a method for in vivo T-ALL transformation driven by the retroviral transduction of hematopoietic progenitors with oncogenic mutant forms NOTCH1 and subsequent transplant into recipient mice. This T-ALL transformation model allows the interaction between the leukemia cells and the bone marrow microenvironment, better recapitulating the physiological conditions that promote the development of the human disease, providing a versatile tool for both experimental therapeutics and functional genetics studies on T-ALL.

CAD204520 Targets NOTCH1 PEST Domain Mutations in Lymphoproliferative Disorders.

NOTCH1 PEST domain mutations are often seen in hematopoietic malignancies, including T-cell acute lymphoblastic leukemia (T-ALL), chronic lymphocytic leukemia (CLL), splenic marginal zone lymphoma (SMZL), mantle cell lymphoma (MCL), and diffuse large B-cell lymphoma (DLBCL). These mutations play a key role in the development and progression of lymphoproliferative tumors by increasing the Notch signaling and, consequently, promoting cell proliferation, survival, migration, and suppressing apoptosis. There is currently no specific treatment available for cancers caused by NOTCH1 PEST domain mutations. However, several NOTCH1 inhibitors are in development. Among these, inhibition of the Sarco-endoplasmic Ca2+-ATPase (SERCA) showed a greater effect in NOTCH1-mutated tumors compared to the wild-type ones. One example is CAD204520, a benzimidazole derivative active in T-ALL cells harboring NOTCH1 mutations. In this study, we preclinically assessed the effect of CAD204520 in CLL and MCL models and showed that NOTCH1 PEST domain mutations sensitize cells to the anti-leukemic activity mediated by CAD204520. Additionally, we tested the potential of CAD204520 in combination with the current first-line treatment of CLL, venetoclax, and ibrutinib. CAD204520 enhanced the synergistic effect of this treatment regimen only in samples harboring the NOTCH1 PEST domain mutations, thus supporting a role for Notch inhibition in these tumors. In summary, our work provides strong support for the development of CAD204520 as a novel therapeutic approach also in chronic lymphoproliferative disorders carrying NOTCH1 PEST domain mutations, emerging as a promising molecule for combination treatment in this aggressive subset of patients.

Circ-MBOAT2 Regulates Angiogenesis via the miR-495/NOTCH1 Axis and Associates with Myocardial Perfusion in Patients with Coronary Chronic Total Occlusion.

Revascularization of coronary chronic total occlusion (CTO) still remains controversial. The factors that impact collateral circulation and myocardial perfusion are of interest. Circular RNA (circRNA) has been shown to regulate the process of angiogenesis. However, the effects of circ-membrane-bound O-acyltransferase domain containing 2 (circ-MBOAT2) on angiogenesis in patients with CTO were unclear. In this study, we evaluated circulating circRNAs and miRNAs in patients with CTO and stable coronary artery disease using high-throughput sequencing. Another cohort of patients were selected to verify the expressions of circ-MBOAT2 and miR-495. The role and mechanism of circ-MBOAT2 in the process of angiogenesis were explored through in vitro and vivo studies. Finally, we came back to a clinical perspective and investigated whether circ-MBOAT2 and miR-495 were associated with the improvement of myocardial perfusion evaluated by single-photon emission computed tomography (SPECT). We found that the expression of circ-MBOAT2 was significantly up-regulated while miR-495 was significantly down-regulated in patients with CTO. The expression of circ-MBOAT2 was negatively correlated with miR-495 in patients with CTO. In an in vitro study, we found that circ-MBOAT2 promoted tube formation and cell migration via the miR-495/NOTCH1 axis in endothelial cells. In an in vivo study, we showed that the inhibition of miR-495 caused the increase in collateral formation in mice after hindlimb ischemia. In a human study, we showed the expressions of circ-MBOAT2 and miR-495 were associated with myocardial perfusion improvement after revascularization of CTO. In conclusion, circ-MBOAT2 regulates angiogenesis via the miR-495/NOTCH1 axis and associates with myocardial perfusion in patients with CTO. Our findings suggest that circ-MBOAT2 and miR-495 may be potential therapeutic targets and prognostic factors for patients with CTO.

Myeloid-specific knockout of Notch-1 inhibits MyD88- and TRIF-mediated TLR signaling pathways by regulating oxidative stress-SHP2 axis, thus restraining aneurysm progression.

OBJECTIVE: Notch-1 is a signal regulatory protein with extensive effects in myeloid cells, but its role in aneurysms remains to be fully clarified. In this study, therefore, the aneurysm mouse model with myeloid-specific knockout of Notch-1 was established to observe the role of Notch-1 in aneurysm progression. METHODS AND RESULTS: The effect of Notch-1 was assessed by pathological staining and Western blotting. It was found that after myeloid-specific knockout of Notch-1 in the aneurysm mouse model, the area of aneurysms and the macrophage infiltration were significantly reduced, the damage to arterial elastic plates was significantly relieved, and the oxidative stress level significantly declined. The results of Western blotting showed that after myeloid-specific knockout of Notch-1, the levels of oxidative stress-related proteins p22 and p47 in aneurysm tissues significantly declined, accompanied by a significant increase in the protein level of Src homology 2 domain-containing tyrosine phosphatase-2 (SHP2). In addition, the levels of phosphorylated myeloid differential protein-88 (MyD88), TIR domain-containing adaptor-inducing interferon-ß (TRIF) and nuclear factor-κB (NF-κB), and inflammatory cytokines interferon-γ (IFN-γ), interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) also significantly decreased after myeloid-specific knockout of Notch-1. Following myeloid-specific knockout of Notch-1, the phagocytic capacity of macrophages was enhanced by promoting the SHP2 signaling pathway. CONCLUSION: Notch-1 in monocytes/macrophages can activate the Toll-like receptor (TLR)-mediated inflammatory and stress responses by activating oxidative stress and inhibiting the SHP2 protein expression, thus facilitating aneurysm progression.

Comprehensive analysis of the proximity-dependent nuclear interactome for the oncoprotein NOTCH1 in live cells.

Notch signaling plays a critical role in cell fate decisions in all cell types. Furthermore, gain-of-function mutations in NOTCH1 have been uncovered in many human cancers. Disruption of Notch signaling has recently emerged as an attractive disease treatment strategy. However, the nuclear interaction landscape of the oncoprotein NOTCH1 remains largely unexplored. We therefore employed here a proximity-dependent biotin identification approach to identify in vivo protein associations with the nuclear Notch1 intracellular domain in live cells. We identified a large set of previously reported and unreported proteins that associate with NOTCH1, including general transcription and elongation factors, DNA repair and replication factors, coactivators, corepressors, and components of the NuRD and SWI/SNF chromatin remodeling complexes. We also found that Notch1 intracellular domain associates with protein modifiers and components of other signaling pathways that may influence Notch signal transduction and protein stability such as USP7. We further validated the interaction of NOTCH1 with histone deacetylase 1 or GATAD2B using protein network analysis, proximity-based ligation, in vivo cross-linking and coimmunoprecipitation assays in several Notch-addicted cancer cell lines. Through data mining, we also revealed potential drug targets for the inhibition of Notch signaling. Collectively, these results provide a valuable resource to uncover the mechanisms that fine-tune Notch signaling in tumorigenesis and inform therapeutic targets for Notch-addicted tumors.

NOTCH1 and CREBBP co-mutations negatively affect the benefit of adjuvant therapy in completely resected EGFR-mutated NSCLC: translational research of phase III IMPACT study.

The phase III IMPACT study (UMIN000044738) compared adjuvant gefitinib with cisplatin plus vinorelbine (cis/vin) in completely resected epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC). Although the primary endpoint of disease-free survival (DFS) was not met, we searched for molecular predictors of adjuvant gefitinib efficacy. Of 234 patients enrolled in the IMPACT study, 202 patients were analyzed for 409 cancer-related gene mutations and tumor mutation burden using resected lung cancer specimens. Frequent somatic mutations included tumor protein p53 (TP53; 58.4%), CUB and Sushi multiple domains 3 (CSMD3; 11.8%), and NOTCH1 (9.9%). Multivariate analysis showed that NOTCH1 co-mutation was a significant poor prognostic factor for overall survival (OS) in the gefitinib group and cAMP response element binding protein (CREBBP) co-mutation for DFS and OS in the cis/vin group. In patients with NOTCH1 co-mutations, gefitinib group had a shorter OS than cis/vin group (Hazard ratio 5.49, 95% CI 1.07-28.00), with a significant interaction (P for interaction = 0.039). In patients with CREBBP co-mutations, the gefitinib group had a longer DFS than the cis/vin group, with a significant interaction (P for interaction = 0.058). In completely resected EGFR-mutated NSCLC, NOTCH1 and CREBBP mutations might predict poor outcome in patients treated with gefitinib and cis/vin, respectively.

NOTCH pathway mutation contributes to inferior prognosis in HBV-infected chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) patients with hepatitis B virus (HBV) infection have a poor prognosis, underlying mechanism remains unclear. NOTCH mutations are frequent in CLL and associated with disease progression and drug resistance. It is also reported to be associated with hepatitis infection in lymphoid malignancies. In order to investigate the relation between the NOTCH pathway and HBV-associated CLL, we studied 98 previously untreated HBV-positive CLL patients and 244 HBV-negative CLL. NOTCH mutations were more frequent in HBV-positive CLL subgroup (p = 0.033). By survival analysis, HBV infection was associated with disease progression and poor survival (p = 0.0099 for overall survival (OS) and p = 0.0446 for time-to-treatment (TTT)). Any lesions of the NOTCH pathway (NOTCH1, NOTCH2, and SPEN) aggravated prognosis. In multivariate analysis, NOTCH mutation retained an independent significance for HBV-infected patients (p = 0.016 for OS and p = 0.023 for TTT). However, HBV positive with NOTCH unmutated had no statistical difference in prognosis compared with HBV-negative patients (p = 0.1706 for OS and p = 0.2387 for TTT), which indicated that NOTCH pathway mutation contributed to inferior prognosis in HBV-infected CLL. In conclusion, a cohort of CLL patients with HBV positive displayed a worse clinical outcome and the status of the NOTCH signaling pathway might play a crucial role.

Generation and characterization of a human induced pluripotent stem cell line heterozygous for a NOTCH1 mutation (NCHi014-A).

NOTCH1 signaling is crucial for cardiovascular development. Numerous studies have identified heterozygous NOTCH1 loss of function and missense variants associated with a spectrum of congenital heart diseases (CHD). We generated induced pluripotent stem cells (iPSC) from a healthy individual to develop a model for NOTCH1+/- iPSC to study the molecular pathogenesis of CHD. NOTCH1+/-iPSC (NCHi014-A) have normal morphology and karyotype, are identical to the parental cell line, express pluripotency markers and have the ability to differentiate to the three germ layers. NOTCH1+/- iPSC can be used as a tool to study the cellular and molecular mechanisms underlying NOTCH1-associated human CHD.

[Forkhead Box M1 Regulates the Proliferation,Invasion,and Drug Resistance of Gastric Cancer Cells via circ_NOTCH1].

Objective To investigate the impacts of forkhead box M1(FOXM1)on the proliferation,invasion,and drug resistance of gastric cancer cells by regulating the circular RNA circ_NOTCH1.Methods Western blotting and real-time quantitative PCR were performed to determine the expression of FOXM1 protein and circ_NOTCH1,respectively,in the gastric cancer tissue,para-carcinoma tissue,human normal gastric mucosa epithelial cell line GES-1 and gastric cancer cell lines MGC-803,HGC-27,and BGC-823.BGC-823 cells were classified into the following groups:control,short hairpin RNA FOXM1(sh-FOXM1)and negative control(sh-NC),small interfering RNA circ_NOTCH1(si-circ_NOTCH1)and negative control(si-NC),and sh-FOXM1+circ_NOTCH1 overexpression plasmid(sh-FOXM1+pcDNA-circ_NOTCH1)and sh-FOXM1+negative control(sh-FOXM1+pcDNA).CCK-8 assay and clone formation assay were employed to measure the cell proliferation,and Transwell assay to measure cell invasion.After treatment with 1.0 mg/L adriamycin for 48 h,the cell resistance in each group was analyzed.Western blotting was employed to determine the expression levels of FOXM1,proliferating cell nuclear antigen(PCNA),Bax,multi-drug resistance-associated protein 1(MRP1),and multi-drug resistance gene 1(MDR1).RNA pull-down and RNA immunoprecipitation were employed to examine the binding of circ_NOTCH1 to FOXM1 protein.Results Compared with those in the para-carcinoma tissue,the expression levels of FOXM1 protein and circ_NOTCH1 in the gastric cancer tissue were up-regulated(all P<0.001).Compared with GES-1 cells,MGC-803,HGC-27,and BGC-823 cells showed up-regulated expression levels of FOXM1 protein and circ_NOTCH1(all P<0.001).Compared with the control group and sh-NC group,the sh-FOXM1 group with down-regulated expression of FOXM1 protein and circ_NOTCH1 showed decreased optical density value,clone formation rate,cell invasion number,and cell viability,down-regulated expression of PCNA,MRP1,and MDR1,and up-regulated expression of Bax protein in BGC-823 cells(all P<0.001).Compared with the control group and the si-NC group,the si-circ_NOTCH1 group with down-regulated expression of circ_NOTCH1 showed decreased optical density value,clone formation rate,cell invasion number,and cell viability,down-regulated expression of PCNA,MRP1,and MDR1,and up-regulated expression of Bax protein in BGC-823 cells(all P<0.001).Compared with sh-FOXM1 group and sh-FOXM1+pcDNA group,the sh-FOXM1+pcDNA-circ_NOTCH1 group with up-regulated expression of circ_NOTCH1 showed increased optical density value,clone formation rate,cell invasion number,and cell viability,up-regulated expression of PCNA,MRP1,and MDR1,and down-regulated expression of Bax protein(all P<0.001).FOXM1 protein was able to interact with circ_NOTCH1.Conclusion Interference with FOXM1 may inhibit the proliferation,invasion,and drug resistance of gastric cancer cells by silencing circ_NOTCH1 expression.

TM2D3, a mammalian homologue of Drosophila neurogenic gene product Almondex, regulates surface presentation of Notch receptors.

Notch signaling is an evolutionarily conserved mechanism required for numerous types of cell fate decisions in metazoans. It mediates short-range communication between cells with receptors and ligands, both of which are expressed on the cell surfaces. In response to the ligand-receptor interaction, the ligand and the extracellular domain of the Notch receptor (NECD) in the complex are internalized into ligand-expressing cells by endocytosis, a prerequisite process for the conformational change of the membrane proximal region of Notch to induce critical proteolytic cleavages for its activation. Here we report that overexpression of transmembrane 2 (TM2) domain containing 3 (TM2D3), a mammalian homologue of Drosophila melanogaster Almondex (Amx), activates Notch1. This activation requires the ligand-binding domain in Notch1 and the C-terminal region containing TM2 domain in TM2D3. TM2D3 physically associates with Notch1 at the region distinct from the ligand-binding domain and enhances expression of Notch1 on the cell surface. Furthermore, cell surface expression of Notch1 and Notch2 is reduced in Tm2d3-deficient cells. Finally, amx-deficient Drosophila early embryos exhibit impaired endocytosis of NECD and Delta ligand, for which surface presentation of Notch is required. These results indicate that TM2D3 is an element involved in Notch signaling through the surface presentation.

Inhibition of the NOTCH and mTOR pathways by nelfinavir as a novel treatment for T cell acute lymphoblastic leukemia.

T cell acute lymphoblastic leukemia (T­ALL), a neoplasm derived from T cell lineage­committed lymphoblasts, is characterized by genetic alterations that result in activation of oncogenic transcription factors and the NOTCH1 pathway activation. The NOTCH is a transmembrane receptor protein activated by γ­secretase. γ­secretase inhibitors (GSIs) are a NOTCH­targeted therapy for T­ALL. However, their clinical application has not been successful due to adverse events (primarily gastrointestinal toxicity), limited efficacy, and drug resistance caused by several mechanisms, including activation of the AKT/mTOR pathway. Nelfinavir is an human immunodeficiency virus 1 aspartic protease inhibitor and has been repurposed as an anticancer drug. It acts by inducing endoplasmic reticulum (ER) stress and inhibiting the AKT/mTOR pathway. Thus, it was hypothesized that nelfinavir might inhibit the NOTCH pathway via γ­secretase inhibition and blockade of aspartic protease presenilin, which would make nelfinavir effective against NOTCH­associated T­ALL. The present study assessed the efficacy of nelfinavir against T­ALL cells and investigated mechanisms of action in vitro and in preclinical treatment studies using a SCL­LMO1 transgenic mouse model. Nelfinavir blocks presenilin 1 processing and inhibits γ­secretase activity as well as the NOTCH1 pathway, thus suppressing T­ALL cell viability. Additionally, microarray analysis of nelfinavir­treated T­ALL cells showed that nelfinavir upregulated mRNA levels of CHAC1 (glutathione­specific γ­glutamylcyclotransferase 1, a negative regulator of NOTCH) and sestrin 2 (SESN2; a negative regulator of mTOR). As both factors are upregulated by ER stress, this confirmed that nelfinavir induced ER stress in T­ALL cells. Moreover, nelfinavir suppressed NOTCH1 mRNA expression in microarray analyses. These findings suggest that nelfinavir inhibited the NOTCH1 pathway by downregulating NOTCH1 mRNA expression, upregulating CHAC1 and suppressing γ­secretase via presenilin 1 inhibition and the mTOR pathway by upregulating SESN2 via ER stress induction. Further, nelfinavir exhibited therapeutic efficacy against T­ALL in an SCL­LMO1 transgenic mouse model. Collectively, these findings highlight the potential of nelfinavir as a novel therapeutic candidate for treatment of patients with T­ALL.