Notch3 overexpression causes arrest of cell cycle progression by inducing Cdh1 expression in human breast cancer cells

NOTCH3 as a prognostic biomarker and its correlation with immune infiltration in gastrointestinal cancers

NOTCH receptor 3 (NOTCH3) is known to regulate the transcription of oncogenes or tumor suppressor genes, thereby playing a crucial role in tumor development, invasion, maintenance, and chemotherapy resistance. However, the specific mechanism of how NOTCH3 drives immune infiltration in gastrointestinal cancer remains uncertain. The expression of NOTCH3 was analyzed through Western blot, PCR, Oncomine database, and the Tumor Immune Estimation Resource (TIMER) site. Kaplan-Meier plotter, PrognoScan database, and gene expression profile interactive analysis (GEPIA) were used to assess the impact of NOTCH3 on clinical prognosis. The correlation between NOTCH3 expression and immune infiltration gene markers was investigated using TIMER and GEPIA. NOTCH3 was found to be commonly overexpressed in various types of gastrointestinal tumors and was significantly associated with poor prognosis. Furthermore, the expression level of NOTCH3 showed a significant correlation with the tumor purity of gastrointestinal tumors and the extent of immune infiltration by different immune cells. Our findings suggest that NOTCH3 may act as a crucial regulator of tumor immune cell infiltration and can serve as a valuable prognostic biomarker in gastrointestinal cancers.

CDCA3 is a potential biomarker for glioma malignancy and targeted therapy

CDCA3, a cell cycle regulator gene that plays a catalytic role in many tumors, was initially identified as a regulator of cell cycle progression, specifically facilitating the transition from the G2 phase to mitosis. However, its role in glioma remains unknown. In this study, bioinformatics analyses (TCGA, CGGA, Rembrandt) shed light on the upregulation and prognostic value of CDCA3 in gliomas. It can also be included in a column chart as a parameter predicting 3- and 5-year survival risk (C index = 0.86). According to Gene Set Enrichment Analysis and gene ontology analysis, the biological processes of CDCA3 are mainly concentrated in the biological activities related to cell cycle such as DNA replication and nuclear division. CDCA3 is closely associated with many classic glioma biomarkers (CDK4, CDK6), and inhibitors of CDK4 and CDK6 have been shown to be effective in tumor therapy. We have demonstrated that high expression of CDCA3 indicates a higher malignancy and poorer prognosis in gliomas.

Inhibition of γ-secretase/Notch pathway as a potential therapy for reversing cancer drug resistance

The mechanism of tumor drug resistance is complex and may involve stem cell maintenance, epithelial-mesenchymal transition, the activation of survival signaling pathways, transporter protein expression, and tumor microenvironment remodeling, all of which are linked to γ-secretase/Notch signaling. Increasing evidence has shown that the activation of the γ-secretase/Notch pathway is a key driver of cancer progression and drug resistance development and that γ-secretase inhibitors (GSIs) may be the most promising agents for reversing chemotherapy resistance of tumors by targeting the γ-secretase/Notch pathway. Here, we systematically summarize the roles in supporting γ-secretase/Notch activation-associated transformation of cancer cells into cancer stem cells, promotion of the EMT process, PI3K/Akt, MEK/ERK and NF-κB activation, enhancement of ABC transporter protein expression, and TME alteration in mediating tumor drug resistance. Subsequently, we analyze the mechanism of GSIs targeting the γ-secretase/Notch pathway to reverse tumor drug resistance and propose the outstanding advantages of GSIs in treating breast cancer drug resistance over other tumors. Finally, we emphasize that the development of GSIs for reversing tumor drug resistance is promising.

Moringa oleifera Lam. Isothiocyanate Quinazolinone Derivatives Inhibit U251 Glioma Cell Proliferation through Cell Cycle Regulation and Apoptosis Induction

A major active constituent of Moringa oleifera Lam. is 4-[(α-L-rhamnose oxy) benzyl] isothiocyanate (MITC). To broaden MITC's application and improve its biological activity, we synthesized a series of MITC quinazolinone derivatives and evaluated their anticancer activity. The anticancer effects and mechanisms of the compound with the most potent anticancer activity were investigated further. Among 16 MITC quinazolinone derivatives which were analyzed, MITC-12 significantly inhibited the growth of U251, A375, A431, HCT-116, HeLa, and MDA-MB-231 cells. MITC-12 significantly inhibited U251 cell proliferation in a time- and dose-dependent manner and decreased the number of EdU-positive cells, but was not toxic to normal human gastric mucosal cells (GES-1). Further, MITC-12 induced apoptosis of U251 cells, and increased caspase-3 expression levels and the Bax:Bcl-2 ratio. In addition, MITC-12 significantly decreased the proportion of U251 cells in the G1 phase and increased it in S and G2 phases. Transcriptome sequencing showed that MITC-12 had a significant regulatory effect on pathways regulating the cell cycle. Further, MITC-12 significantly decreased the expression levels of the cell cycle-related proteins CDK2, cyclinD1, and cyclinE, and increased those of cyclinA2, as well as the p-JNK:JNK ratio. These results indicate that MITC-12 inhibits U251 cell proliferation by inducing apoptosis and cell cycle arrest, activating JNK, and regulating cell cycle-associated proteins. MITC-12 has potential for use in the prevention and treatment of glioma.

Silencing Notch4 promotes tumorigenesis and inhibits metastasis of triple-negative breast cancer via Nanog and Cdc42

Elucidation of individual Notch protein biology in specific cancer is crucial to develop safe, effective, and tumor-selective Notch-targeting therapeutic reagents for clinical use [1]. Here, we explored the Notch4 function in triple-negative breast cancer (TNBC). We found that silencing Notch4 enhanced tumorigenic ability in TNBC cells via upregulating Nanog expression, a pluripotency factor of embryonic stem cells. Intriguingly, silencing Notch4 in TNBC cells suppressed metastasis via downregulating Cdc42 expression, a key molecular for cell polarity formation. Notably, downregulation of Cdc42 expression affected Vimentin distribution, but not Vimentin expression to inhibit EMT shift. Collectively, our results show that silencing Notch4 enhances tumorigenesis and inhibits metastasis in TNBC, indicating that targeting Notch4 may not be a potential strategy for drug discovery in TNBC.

Clinical significance of Notch receptors in triple negative breast cancer

BACKGROUND

The Notch signaling pathway is an evolutionary conserved cell signaling pathway that plays an indispensable role in essential developmental processes. Aberrant activation of Notch pathway is known to initiate wide array of diseases and cancers.

OBJECTIVE

To evaluate the clinical significance of Notch receptors in Triple Negative Breast Cancer.

METHODS

We evaluated the association between Notch receptors and clinicopathological parameters including disease-free survival and overall survival of one hundred TNBC patients by immunohistochemistry.

RESULTS

Positive expression of nuclear Notch1 receptor (18%) was found be significantly correlated with positive lymph node (p = 0.009), high BR score (p = 0.02) and necrosis (p = 0.004) while cytoplasmic expression of Notch2 receptor (26%) was significantly correlated with metastasis (p = 0.05), worse DFS (p = 0.05) and poor OS (p = 0.02) in TNBC patients. Membrane (18%) and cytonuclear (3%) Notch3 expression were significantly associated with poorly differentiated tumors (p = 0.007), high BR score (p = 0.002) and necrosis (p = 0.03) respectively. However, cytoplasmic Notch3 and Notch4 expression were negatively correlated with poor prognostic factors.

CONCLUSIONS

Our data indicated that Notch receptors play a key role in promoting TNBC and mainly, Notch2 may contribute to poor prognosis of the disease. Hence, it is implicated that Notch2 may serve as a potential biomarker and therapeutic target for TNBC.

Notch signaling pathway: a comprehensive prognostic and gene expression profile analysis in breast cancer

Breast cancer is a complex disease exhibiting a great degree of heterogeneity due to different molecular subtypes. Notch signaling regulates the differentiation of breast epithelial cells during normal development and plays a crucial role in breast cancer progression through the abnormal expression of the Notch up-and down-stream effectors. To date, there are only a few patient-centered clinical studies using datasets characterizing the role of Notch signaling pathway regulators in breast cancer; thus, we investigate the role and functionality of these factors in different subtypes using publicly available databases containing records from large studies. High-throughput genomic data and clinical information extracted from TCGA were analyzed. We performed Kaplan-Meier survival and differential gene expression analyses using the HALLMARK_NOTCH_SIGNALING gene set. To determine if epigenetic regulation of the Notch regulators contributes to their expression, we analyzed methylation levels of these factors using the TCGA HumanMethylation450 Array data. Notch receptors and ligands expression is generally associated with the tumor subtype, grade, and stage. Furthermore, we showed gene expression levels of most Notch factors were associated with DNA methylation rate. Modulating the expression levels of Notch receptors and effectors can be a potential therapeutic approach for breast cancer. As we outline herein, elucidating the novel prognostic and regulatory roles of Notch implicate this pathway as an essential mediator controlling breast cancer progression.

Notch3 Transactivates Glycogen Synthase Kinase-3-Beta and Inhibits Epithelial-to-Mesenchymal Transition in Breast Cancer Cells

As a critical transformational process in the attributes of epithelial cells, epithelial-to-mesenchymal transition (EMT) is involved in tumor invasion, metastasis, and resistance to treatment, which contributes to the ultimate death of some patients with breast cancer. Glycogen synthase kinase-3-beta (GSK3β) is thought to be an EMT suppressor that down-regulates the protein, snail, a zinc finger transcription inhibitor, and regulates E-cadherin expression and the Wnt signaling pathway. Our previous studies have shown that Notch3 also inhibits EMT in breast cancer. In mammary gland cells, GSK3β physically bound and phosphorylated the intracellular domain of two Notch paralogs: N1ICD was positively regulated, but N2ICD was negatively regulated; however, the relationship between Notch3, GSK3β, and EMT in breast cancer is still unclear and crosstalk between Notch3 and GSK3β has not been widely investigated. In this study, we revealed that Notch3 was an essential antagonist of EMT in breast cancer cells by transcriptionally upregulating GSK3β. In breast cancer, MCF-7 and MDA-MB-231 cell lines, the silencing of Notch3 reduced GSK3β expression, which is sufficient to induce EMT. Conversely, ectopic Notch3 expression re-activated GSK3β and E-cadherin. Mechanistically, Notch3 can bind to the GSK3β promoter directly and activate GSK3β transcription. In human breast cancer samples, Notch3 expression is positively associated with GSK3β (r = 0.416, p = 0.001); moreover, high expressions of Notch3 and GSK3β mRNA are correlated to better relapse-free survival in all breast cancer patients via analysis in "the Kaplan-Meier plotter" database. In summary, our preliminary results suggested that Notch3 might inhibit EMT by trans-activating GSK3β in breast cancer cells. The suppression of Notch3 expression may contribute to EMT by transcriptionally downregulating GSK3β in breast cancer.

Herbal Ingredients in the Prevention of Breast Cancer: Comprehensive Review of Potential Molecular Targets and Role of Natural Products

Among various cancers, breast cancer is the most prevalent type in women throughout the world. Breast cancer treatment is challenging due to complex nature of the etiology of disease. Cell division cycle alterations are often encountered in a variety of cancer types including breast cancer. Common treatments include chemotherapy, surgery, radiotherapy, and hormonal therapy; however, adverse effects and multidrug resistance lead to complications and noncompliance. Accordingly, there is an increasing demand for natural products from medicinal plants and foods. This review summarizes molecular mechanisms of signaling pathways in breast cancer and identifies mechanisms by which natural compounds may exert their efficacy in the treatment of breast cancer.

Notch Signaling in Breast Tumor Microenvironment as Mediator of Drug Resistance

Notch signaling dysregulation encourages breast cancer progression through different mechanisms such as stem cell maintenance, cell proliferation and migration/invasion. Furthermore, Notch is a crucial driver regulating juxtracrine and paracrine communications between tumor and stroma. The complex interplay between the abnormal Notch pathway orchestrating the activation of other signals and cellular heterogeneity contribute towards remodeling of the tumor microenvironment. These changes, together with tumor evolution and treatment pressure, drive breast cancer drug resistance. Preclinical studies have shown that targeting the Notch pathway can prevent or reverse resistance, reducing or eliminating breast cancer stem cells. In the present review, we will summarize the current scientific evidence that highlights the involvement of Notch activation within the breast tumor microenvironment, angiogenesis, extracellular matrix remodeling, and tumor/stroma/immune system interplay and its involvement in mechanisms of therapy resistance.

Different Expression Levels of DLK2 Inhibit NOTCH Signaling and Inversely Modulate MDA-MB-231 Breast Cancer Tumor Growth In Vivo

NOTCH signaling is implicated in the development of breast cancer tumors. DLK2, a non-canonical inhibitor of NOTCH signaling, was previously shown to be involved in skin and breast cancer. In this work, we studied whether different levels of DLK2 expression influenced the breast cancer characteristics of MDA-MB-231 cells. We found that DLK2 overexpression inhibited NOTCH activation in a dose-dependent manner. Moreover, depending on the level of inhibition of NOTCH1 activation generated by different levels of DLK2 expression, cell proliferation, cell cycle dynamics, cell apoptosis, cell migration, and tumor growth in vivo were affected in opposite directions. Low levels of DLK2 expression produced a slight inhibition of NOTCH1 activation, and enhanced MDA-MB-231 cell invasion in vitro and cell proliferation both in vitro and in vivo. In contrast, MDA-MB-231 cells expressing elevated levels of DLK2 showed a strong inhibition of NOTCH1 activation, decreased cell proliferation, increased cell apoptosis, and were unable to generate tumors in vivo. In addition, DLK2 expression levels also affected some members of other cell signaling pathways implicated in cancer, such as ERK1/2 MAPK, AKT, and rpS6 kinases. Our data support an important role of DLK2 as a protein that can finely regulate NOTCH signaling and affect the tumor properties and growth dynamics of MDA-MB-231 breast cancer cells.

Molecular-Genetic Portrait of Breast Cancer with Triple Negative Phenotype

Simple Summary

Breast cancer is a genetically heterogeneous disease with different molecular biological and clinical characteristics. The available knowledge about the genetic heterogeneity of the most aggressive molecular subtype of breast cancer—triple-negative—has led to discoveries in drug treatment. Identification of the molecular-genetic phenotype of breast cancer is an important prognostic factor of the disease and allows personalization of the patient’s treatment.

Abstract

Understanding of the genetic mechanisms and identification of the biological markers of tumor progression that form the individual molecular phenotype of transformed cells can characterize the degree of tumor malignancy, the ability to metastasize, the hormonal sensitivity, and the effectiveness of chemotherapy, etc. Breast cancer (BC) is a genetically heterogeneous disease with different molecular biological and clinical characteristics. The available knowledge about the genetic heterogeneity of the most aggressive molecular subtype of breast cancer—triple-negative (TN)—has led to discoveries in drug treatment, including the use of DNA damaging agents (platinum and PARP inhibitors) for these tumors, as well as the use of immunotherapy. Most importantly, the ability to prescribe optimal drug treatment regimens for patients with TNBC based on knowledge of the molecular-genetic characteristics of this subtype of BC will allow the achievement of high rates of overall and disease-free survival. Thus, identification of the molecular-genetic phenotype of breast cancer is an important prognostic factor of the disease and allows personalization of the patient’s treatment.

Notch3 inhibits cell proliferation and tumorigenesis and predicts better prognosis in breast cancer through transactivating PTEN

Notch receptors (Notch1-4) play critical roles in tumorigenesis and metastasis of malignant tumors, including breast cancer. Although abnormal Notch activation is related to various tumors, the importance of single receptors and their mechanism of activation in distinct breast cancer subtypes are still unclear. Previous studies by our group demonstrated that Notch3 may inhibit the emergence and progression of breast cancer. PTEN is a potent tumor suppressor, and its loss of function is sufficient to promote the occurrence and progression of tumors. Intriguingly, numerous studies have revealed that Notch1 is involved in the regulation of PTEN through its binding to CBF-1, a Notch transcription factor, and the PTEN promoter. In this study, we found that Notch3 and PTEN levels correlated with the luminal phenotype in breast cancer cell lines. Furthermore, we demonstrated that Notch3 transactivated PTEN by binding CSL-binding elements in the PTEN promoter and, at least in part, inhibiting the PTEN downstream AKT-mTOR pathway. Notably, Notch3 knockdown downregulated PTEN and promoted cell proliferation and tumorigenesis. In contrast, overexpression of the Notch3 intracellular domain upregulated PTEN and inhibited cell proliferation and tumorigenesis in vitro and in vivo. Moreover, inhibition or overexpression of PTEN partially reversed the promotion or inhibition of cell proliferation induced by Notch3 alterations. In general, Notch3 expression positively correlated with elevated expression of PTEN, ER, lower Ki-67 index, and incidence of involved node status and predicted better recurrence-free survival in breast cancer patients. Therefore, our findings demonstrate that Notch3 inhibits breast cancer proliferation and suppresses tumorigenesis by transactivating PTEN expression.

miR-106a-363 cluster in extracellular vesicles promotes endogenous myocardial repair via Notch3 pathway in ischemic heart injury

Endogenous capability of the post-mitotic human heart holds great promise to restore the injured myocardium. Recent evidence indicates that the extracellular vesicles (EVs) regulate cardiac homeostasis and regeneration. Here, we investigated the molecular mechanism of EVs for self-repair. We isolated EVs from human iPSC-derived cardiomyocytes (iCMs), which were exposed to hypoxic (hEVs) and normoxic conditions (nEVs), and examined their roles in in vitro and in vivo models of cardiac injury. hEV treatment significantly improved the viability of hypoxic iCMs in vitro and cardiac function of severely injured murine myocardium in vivo. Microarray analysis of the EVs revealed significantly enriched expression of the miR-106a-363 cluster (miR cluster) in hEVs vs. nEVs. This miR cluster preserved survival and contractility of hypoxia-injured iCMs and maintained murine left-ventricular (LV) chamber size, improved LV ejection fraction, and reduced myocardial fibrosis of the injured myocardium. RNA-Seq analysis identified Jag1-Notch3-Hes1 as a target intracellular pathway of the miR cluster. Moreover, the study found that the cell cycle activator and cytokinesis genes were significantly up-regulated in the iCMs treated with miR cluster and Notch3 siRNA. Together, these results suggested that the miR cluster in the EVs stimulated cardiomyocyte cell cycle re-entry by repressing Notch3 to induce cell proliferation and augment myocardial self-repair. The miR cluster may represent an effective therapeutic approach for ischemic cardiomyopathy.

Coexpressed Genes That Promote the Infiltration of M2 Macrophages in Melanoma Can Evaluate the Prognosis and Immunotherapy Outcome

Purpose

To improve immunotherapy efficacy for melanoma, a coexpression network and key genes of M2 macrophages in melanoma were explored. A prognostic risk assessment model was established for M2-related coexpressed genes, and the role of M2 macrophages in the immune microenvironment of melanoma was elucidated.

Method

We obtained mRNA data from melanoma and peritumor tissue samples from The Cancer Genome Atlas-skin cutaneous melanoma (TCGA-SKCM). Then, we used CIBERSORT to calculate the proportion of M2 macrophage cells. A coexpression module most related to M2 macrophages in TCGA-SKCM was determined by analyzing the weighted gene coexpression network, and a coexpression network was established. After survival analysis, factors with significant results were incorporated into a Cox regression analysis to establish a model. The model's essential genes were analyzed using functional enrichment, GSEA, and subgroup and total carcinoma. Finally, external datasets GSE65904 and GSE78220 were used to verify the prognostic risk model.

Results

The yellow-green module was the coexpression module most related to M2 macrophages in TCGA-SKCM; NOTCH3, DBN1, KDELC2, and STAB1 were identified as the essential genes that promoted the infiltration of M2 macrophages in melanoma. These genes are concentrated in antigen treatment and presentation, chemokine, cytokine, the T cell receptor pathway, and the IFN-γ pathway. These factors were analyzed for survival, and factors with significant results were included in a Cox regression analysis. According to the methods, a model related to M2-TAM coexpressed gene was established, and the formula was risk score = 0.25^∗NOTCH3 + 0.008^∗ DBN1 − 0.031^∗KDELC2 − 0.032^∗STAB1. The new model was used to perform subgroup evaluation and external queue validation. The results showed good prognostic ability.

Conclusion

We proposed a Cox proportional hazards regression model associated with coexpression genes of melanoma M2 macrophages that may provide a measurement method for generating prognosis scores in patients with melanoma. Four genes coexpressed with M2 macrophages were associated with high levels of infiltration of M2 macrophages. Our findings may provide significant candidate biomarkers for the treatment and monitoring of melanoma.

Functional Gene Expression Differentiation of the Notch Signaling Pathway in Female Reproductive Tract Tissues-A Comprehensive Review With Analysis

The Notch pathway involves evolutionarily conserved signaling regulating the development of the female tract organs such as breast, ovary, cervix, and uterine endometrium. A great number of studies revealed Notch aberrancies in association with their carcinogenesis and disease progression, the management of which is still challenging. The present study is a comprehensive review of the available literature on Notch signaling during the normal development and carcinogenesis of the female tract organs. The review has been enriched with our analyses of the TCGA data including breast, cervical, ovarian, and endometrial carcinomas concerning the effects of Notch signaling at two levels: the core components and downstream effectors, hence filling the lack of global overview of Notch-driven carcinogenesis and disease progression. Phenotype heterogeneity regarding Notch signaling was projected in two uniform manifold approximation and projection algorithm dimensions, preceded by the principal component analysis step reducing the data burden. Additionally, overall and disease-free survival analyses were performed with the optimal cutpoint determination by Evaluate Cutpoints software to establish the character of particular Notch components in tumorigenesis. In addition to the review, we demonstrated separate models of the examined cancers of the Notch pathway and its targets, although expression profiles of all normal tissues were much more similar to each other than to its cancerous compartments. Such Notch-driven cancerous differentiation resulted in a case of opposite association with DFS and OS. As a consequence, target genes also show very distinct profiles including genes associated with cell proliferation and differentiation, energy metabolism, or the EMT. In conclusion, the observed Notch associations with the female tract malignancies resulted from differential expression of target genes. This may influence a future analysis to search for new therapeutic targets based on specific Notch pathway profiles.

Defective cell proliferation is an attribute of overexpressed Notch1 receptor and impaired autophagy in Fanconi Anemia

Fanconi Anemia (FA) is an inherited bone marrow failure syndrome caused by mutation in FA pathway proteins, involved in Interstrand Cross Link (ICL) repair. FA cells exhibit in vitro proliferation arrest due to accumulated DNA damage, hence understanding the rescue mechanism that renders proliferation advantage is required. Gene expression profiling performed in FA patients Peripheral Blood Mononuclear Cells (PBMCs) revealed a wide array of dysregulated biological processes. Functional enrichment and gene clustering analysis showed crippled autophagy process and escalated Notch signalling pathway in FA clinical samples and cell lines. Notch pathway mediators overexpression were reverted in FANCA mutant cells when treated with Rapamycin, an autophagy inducer. Additionally, Rapamycin stabilized cell viability after treatment with the DNA damaging agent, MitomycinC (MMC) and enhanced cell proliferation genes expression in FANCA mutant cells. Inherently FANCA mutant cells express impaired autophagy; thus activation of autophagy channelizes Notch signalling cascade and sustains cell viability.

A lncRNA landscape in breast cancer reveals a potential role for AC009283.1 in proliferation and apoptosis in HER2-enriched subtype

Breast cancer is the most commonly diagnosed neoplasm in women worldwide with a well-recognized heterogeneous pathology, classified into four molecular subtypes: Luminal A, Luminal B, HER2-enriched and Basal-like, each one with different biological and clinical characteristics. Long non-coding RNAs (lncRNAs) represent 33% of the human transcriptome and play critical roles in breast carcinogenesis, but most of their functions are still unknown. Therefore, cancer research could benefit from continued exploration into the biology of lncRNAs in this neoplasm. We characterized lncRNA expression portraits in 74 breast tumors belonging to the four molecular subtypes using transcriptome microarrays. To infer the biological role of the deregulated lncRNAs in the molecular subtypes, we performed co-expression analysis of lncRNA-mRNA and gene ontology analysis. We identified 307 deregulated lncRNAs in tumor compared to normal tissue and 354 deregulated lncRNAs among the different molecular subtypes. Through co-expression analysis between lncRNAs and protein-coding genes, along with gene enrichment analysis, we inferred the potential function of the most deregulated lncRNAs in each molecular subtype, and independently validated our results taking advantage of TCGA data. Overexpression of the AC009283.1 was observed in the HER2-enriched subtype and it is localized in an amplification zone at chromosome 17q12, suggesting it to be a potential tumorigenic lncRNA. The functional role of lncRNA AC009283.1 was examined through loss of function assays in vitro and determining its impact on global gene expression. These studies revealed that AC009283.1 regulates genes involved in proliferation, cell cycle and apoptosis in a HER2 cellular model. We further confirmed these findings through ssGSEA and CEMITool analysis in an independent HER2-amplified breast cancer cohort. Our findings suggest a wide range of biological functions for lncRNAs in each breast cancer molecular subtype and provide a basis for their biological and functional study, as was conducted for AC009283.1, showing it to be a potential regulator of proliferation and apoptosis in the HER2-enriched subtype.

PD-L1 is overexpressed on breast cancer stem cells through notch3/mTOR axis

The T-cell inhibitory molecule PD-L1 is expressed on a fraction of breast cancer cells. The distribution of PD-L1 on the different subpopulations of breast cancer cells is not well-defined. Our aim was to study the expression level of PD-L1 on breast cancer stem-like (CSC-like) cells and their differentiated-like counterparts. We used multi-parametric flow cytometry to measure PD-L1 expression in different subpopulations of breast cancer cells. Pathway inhibitors, quantitative immunofluorescence, cell sorting, and western blot were used to investigate the underlying mechanism of PD-L1 upregulation in CSC-like cells. Specifically, PD-L1 was overexpressed up to three folds on breast CSC-like cells compared with more differentiated-like cancer cells. Functional in vitro and in vivo assays show higher stemness of PD-L1^hi as compared with PD-L1^lo cells. Among different pathways examined, PD-L1 expression on CSCs was partly dependant on Notch, and/or PI3K/AKT pathway activation. The effect of Notch inhibitors on PD-L1 overexpression in CSCs was completely abrogated upon mTOR knockdown. Specific knockdown of different Notch receptors shows Notch3 as a mediator for PD-L1 overexpression on CSCs and important for maintaining their stemness. Indeed, Notch3 was found to be overexpressed on PD-L1^hi cells and specific knockdown of Notch3 abolished the effect of notch inhibitors and ligands on PD-L1 expression as well as mTOR activation. Our data demonstrated that overexpression of PD-L1 on CSCs is partly mediated by the notch pathway through Notch3/mTOR axis. We propose that these findings will help in a better design of anti-PD-L1 combination therapies to treat breast cancer effectively.

The frequency of CpG and non-CpG methylation of Notch3 gene promoter determines its expression levels in breast cancer cells

Notch3 can act as a tumor suppressor in the breast cancer epithelial cells. Unfortunately, Notch3 expression is decreased or lost, especially in triple-negative breast cancer (TNBC) cells, and the reasons remain unclear. Here, we found Notch3 was upregulated in MDA-MB-231 cells with 5-Aza treatment. Two CpG islands were observed in notch3 promoter. Interestingly, bisulfite sequencing exhibited that large amounts of unconverted cytosines were not only followed by guanine, but also adenine, cytosine and thymine, which implied that there simultaneously existed CpG and non-CpG methylation in notch3 promoter. To better analyze the methylation frequency of non-CpG locus, we designed CpG/non-CpG methylation analysis software. The results showed that the methylation frequency of notch3 gene in different breast cancer cell lines was in order T47D, MCF-7, SKBR3, BT-549 and MDA-MB-231. Furthermore, we identified that DNMT3b, DNMT1, DNMT3L, Mecp2 and EZH2 were important regulators of non-CpG locus of notch3 gene. Immunohistochemistry staining revealed a negative correlation between EZH2 and Notch3 from 22 luminal and 26 TNBC cases. In vitro methylation combined luciferase activity assays showed that non-CpG methylation was still crucial cause leading to notch3 transcriptional repression in TNBC. Our findings provide possible explanation for the downregulation or loss of Notch3 expression in TNBC.

N3ICD with the transmembrane domain can effectively inhibit EMT by correcting the position of tight/adherens junctions

EMT allows a polarized epithelium to lose epithelial integrity and acquire mesenchymal characteristics. Previously, we found that overexpression of the intracellular domain of Notch3 (N3ICD) can inhibit EMT in breast cancer cells. In this study, we aimed to elucidate the influence of N3ICD or N3ICD combined with the transmembrane domain (TD+N3ICD) on the expression and distribution of TJs/AJs and polar molecules. We found that although N3ICD can upregulate the expression levels of the above-mentioned molecules, TD+N3ICD can inhibit EMT more effectively than N3ICD alone. TD+N3ICD overexpression upregulated the expression of endogenous full-length Notch3 and contributed to correcting the position of TJs/AJs molecules and better acinar structures formation. Co-immunoprecipitation results showed that the upregulated endogenous full-length Notch3 could physically interact with E-ca in MDA-MB-231/pCMV-(TD+N3ICD) cells. Collectively, our data indicate that overexpression of TD+N3ICD can effectively inhibit EMT, resulting in better positioning of TJs/AJs molecules and cell-cell adhesion in breast cancer cells. Abbreviations: EMT: Epithelial-mesenchymal transition; TJs: Tight junctions; AJs: Adherens junctions; aPKC: Atypical protein kinase C; Crb: Crumbs; Lgl: Lethal (2) giant larvae; LLGL2: lethal giant larvae homolog 2; PAR: Partitioning defective; PATJ: Pals1-associated TJ protein.

Shikonin induces apoptosis and prosurvival autophagy in human melanoma A375 cells via ROS-mediated ER stress and p38 pathways

Shikonin, a botanical drug extracted from Lithospermum erythrorhizon, exhibits anti-cancer effects in various cancer cell lines. However, the mechanisms underlying these effects have not been completely elucidated yet. Here, we showed that Shikonin induces apoptosis and autophagy in A375 cells and inhibits their proliferation. Shikonin caused G2/M phase arrest through upregulation of p21 and downregulation of cyclin B1. Shikonin significantly triggered ER stress-mediated apoptosis by upregulating the expression of p-eIF2α, CHOP, and cleaved caspase-3. It also induced protective autophagy by activating the p38 pathway, followed by an increase in the levels of p-p38, LC3B-II, and Beclin 1. Upon suppression of autophagy by 3-methyladenine, Shikonin-induced apoptosis was enhanced in A375 cells. Moreover, after pretreatment with N-acetyl-cysteine, Shikonin increased the production of reactive oxygen species that are involved in regulating ER stress-mediated apoptosis and p38-activated autophagy, as evidenced by the reversion of cell viability and apoptosis and a decrease in p-eIF2α, CHOP, p-p38, LC3B-II, and Beclin 1 levels. Thus, we demonstrated that Shikonin induced apoptosis and autophagy in A375 cells via the activation of ROS-mediated ER stress and p38 pathways, indicating that Shikonin can serve as a potential agent for human melanoma therapy.

Notch signaling in breast cancer: From pathway analysis to therapy

The Notch signaling pathway, which is highly conserved from sea urchins to humans, plays an important role in cell-differentiation, survival, proliferation, stem-cell renewal, and determining cell fate during development and morphogenesis. It is well established that signaling pathways are dysregulated in a wide-range of diseases, including human malignancies. Studies suggest that the dysregulation of the Notch pathway contributes to carcinogenesis, cancer stem cell renewal, angiogenesis, and chemo-resistance. Elevated levels of Notch receptors and ligands have been associated with cancer-progression and poor survival. Furthermore, the Notch signaling pathway regulates the transcriptional activity of key target genes through crosstalk with several other signaling pathways. Indeed, increasing evidence suggests that the Notch signaling pathway may serve as a therapeutic target for the treatment of several cancers, including breast cancer. Researchers have demonstrated the anti-tumor properties of Notch inhibitors in various cancer types. Currently, Notch inhibitors are being evaluated for anticancer efficacy in a number of clinical-trials. However, because there are multiple Notch receptors that can exhibit either oncogenic or tumor-suppressing roles in various cells, it is important that the Notch inhibitors are specific to particular receptors that are tumorigenic in nature. This review critically evaluates existing Notch inhibitory drugs and strategies and summarizes the previous discoveries, current understandings, and recent developments in support of Notch receptors as therapeutic targets in breast cancer.

Knockdown of nucleophosmin 1 suppresses proliferation of triple-negative breast cancer cells through activating CDH1/Skp2/p27kip1 pathway

Background

NPM1 is a multifunctional phosphoprotein that commutes between the cytoplasm and nucleus in cell cycle process, which appears to be actively involved in tumorigenesis. Herein, we sought to investigate the possible role and prognostic value of NPM1 in triple-negative breast cancer (TNBC).

Methods

An array of public databases, including bc-GenExMiner v4.0, GOBO, GEPIA, UAL-CAN, ONCOMINE database and Kaplan-Meier plotter, were used to investigate the expression feature and potential function of NPM1 in TNBC. Immunohistochemistry, immunofluorescence, proliferation and colony formation, flow cytometry and western-blotting assays were used to analyze and verify the function and relevant mechanism of NPM1 in TNBC tissues and cells.

Results

According to analysis from bc-GenExMiner, the expression level of NPM1 was significantly higher in basal-like subtypes than luminal-A, HER-2 or normal-like subtypes of breast cancer (P<0.0001). GOBO database analysis indicated that the expression of NPM1 in basal-A or basal-B was significantly higher than luminal-like breast cancer cells. Immunohistochemistry assay in 52 TNBC tissue samples showed that positive expression of Ki-67 was 93.5% in the high-NPM1-expression group and 66.7% in the low-NPM1-expression group, respectively (P=0.032). Proliferation and colony formation assays demonstrated that inhibition of NPM1 suppressed cell growth by approximately 2-fold and reduced the number of colonies by 3-4-fold in MDA-MB-231 and BT549 cells. Moreover, inhibition of NPM1 in MDA-MB-231 and BT549 cells increased the percentage of cells at G0/G1 phase and decreased the percentage of cells at both S and G2/M phase, as compared with control counterparts. Western-blotting results showed that down-regulation of NPM1 could elevate CDH1 and p27kip1 expression, while decrease Skp2 expression both in MDA-MB-231 and BT549 cells. In addition, high mRNA expression of NPM1 correlated with shorter RFS (HR=1.64, P=0.00013) and OS (HR=2.45, P=0.00034) in patients with TNBC.

Conclusions

NPM1 is significantly high expressed basal-like/triple-negative breast cancer and is correlated with shorter RFS and OS in this subset of patients. Knockdown of NPM1 impairs the proliferative capacity of TNBC cells via activation of the CDH1/Skp2/p27kip1 pathway. Targeting NPM1 is a potential therapeutic strategy against TNBC.

The Role of Notch3 in Cancer

The Notch family is a highly conserved gene group that regulates cell-cell interaction, embryogenesis, and tissue commitment. This review article focuses on the third Notch family subtype, Notch3. Regulation via Notch3 signaling was first implicated in vasculogenesis. However, more recent findings suggest that Notch3 signaling may play an important role in oncogenesis, tumor maintenance, and resistance to chemotherapy. Its role is mainly oncogenic, although in some cancers it appears to be tumor suppressive. Despite the wealth of published literature, it remains relatively underexplored and requires further research to shed more light on its role in cancer development, determine its tissue-specific function, and elaborate novel treatment strategies. Herein we summarize the role of Notch3 in cancer, possible mechanisms of its action, and current cancer treatment strategies targeting Notch3 signaling.

IMPLICATIONS FOR PRACTICE

The Notch family is a highly conserved gene group that regulates cell-cell interaction, embryogenesis, and tissue commitment. This review summarizes the existing data on the third subtype of the Notch family, Notch3. The role of Notch3 in different types of cancers is discussed, as well as implications of its modification and new strategies to affect Notch3 signaling activity.

Histone deacetylase SIRT6 inhibits glioma cell growth through down-regulating NOTCH3 expression

Gliomas are the most common brain tumors of the central nervous system. In this study, we investigated the molecular mechanisms and biological function of SIRT6 in human gliomas. The expression levels of SIRT6 in glioma tissues and cells were analyzed by qRT-PCR and western blot analysis. CCK8 and clonogenicity assays were performed to detect the cell proliferation. Furthermore, the migration and invasion of glioma cells were examined by transwell assays. It was found that the expression of SIRT6 was significantly lower in human glioma tissues or cell lines compared with the normal brain tissue or NHA. Up-regulated SIRT6 significantly decreased cell proliferation, migration and invasion of U87 and U251 cells. By contrast, knockdown of SIRT6 dramatically increased cell proliferation, migration and invasion of U87 and U251 cells. Moreover, over expression of NOTCH3 significantly increased the cell proliferation, migration, and invasion of U87 and U251 cells. However, these effects were abolished after overexpression of SIRT6. These results suggest that SIRT6 may suppress cell proliferation, migration, and invasion via inhibition of the NOTCH3 signaling pathway in glioma.

Downregulated long non-coding RNA CLMAT3 promotes the proliferation of colorectal cancer cells by targeting regulators of the cell cycle pathway

Over-expression of long non-coding RNA (lncRNA)-CLMAT3 is significantly associated with colorectal liver metastasis and is an independent predictor of poor survival for colorectal cancer patients. However, as little is known regarding the role of this gene in the proliferation of colorectal cancer in vitro, we investigated the involvement of lncRNA-CLMAT3 in colorectal cancer cell proliferation. In this study, we demonstrate that lncRNA-CLMAT3 expression was significantly increased in colorectal cancer cells compared with a normal intestinal mucous cell line and that inhibition of lncRNA-CLMAT3 suppressed colorectal cancer cell proliferation in vitro. We also found that this reduced colorectal cancer cell proliferation due to lncRNA-CLMAT3 knockdown is associated with G0/G1 cell-cycle arrest induction and apoptosis enhancement. Furthermore, lncRNA-CLMAT3 knockdown enhanced Cdh1 expression and resulted in p27Kip accumulation via increased Skp2 protein ubiquitination. Taken together, our findings suggest that reducing lncRNA-CLMAT3 inhibits colorectal cancer cell proliferation by affecting cell cycle components.

The Notch-3 receptor: A molecular switch to tumorigenesis?

The Notch pathway is a highly conserved pathway increasingly implicated with the progression of human cancers. Of the four existing receptors associated with the pathway, the deregulation in the expression of the Notch-3 receptor is associated with more aggressive disease and poor prognosis. Selective targeting of this receptor has the potential to enhance current anti-cancer treatments. Molecular profiling strategies are increasingly incorporated into clinical decision making. This review aims to evaluate the clinical potential of Notch-3 within this new era of personalised medicine.

Different expression levels of DLK1 inversely modulate the oncogenic potential of human MDA-MB-231 breast cancer cells through inhibition of NOTCH1 signaling

NOTCH receptors participate in cancer cell proliferation and survival. Accumulated evidence indicates that, depending on the cellular context, these receptors can function as oncogenes or as tumor-suppressor genes. The epidermal growth factor-like protein delta-like homolog (DLK)1 acts as a NOTCH inhibitor and is involved in the regulation of normal and tumoral growth. In this work, we focused on the role of DLK1 in the control of breast cancer cell growth, a tumor type in which NOTCH receptors have been shown to play both opposite roles. We found that human DLK1 inhibits NOTCH signaling in MDA-MB-231 breast cancer cells. The proliferation rate and invasion capabilities of these cells depended on the level of NOTCH activation and signaling, as regulated by DLK1. High levels of DLK1 expression led to a significant decrease in NOTCH signaling, which was associated with a decrease in breast cancer cell proliferation and invasion. On the contrary, lower levels of NOTCH inhibition, caused by lower levels of DLK1 overexpression, led to enhanced in vitro MDA-MB-231 cell invasion, and to both in vitro and in vivo increased cell proliferation. The data presented in this work suggest that a fine regulation of NOTCH signaling plays an important role in the control of breast cancer cell proliferation and invasion.-Nueda, M.-L., Naranjo, A.-I., Baladrón V., Laborda, J. Different expression levels of DLK1 inversely modulate the oncogenic potential of human MDA-MB-231 breast cancer cells through inhibition of NOTCH1 signaling.

MCAM/CD146 promotes tamoxifen resistance in breast cancer cells through induction of epithelial-mesenchymal transition, decreased ERα expression and AKT activation

Tamoxifen resistance presents a prominent clinical challenge in endocrine therapy for hormone sensitive breast cancer. However, the underlying mechanisms that contribute to tamoxifen resistance are not fully understood. In this study, we established a tamoxifen resistant MCF-7 cell line (MCF-7-Tam-R) by continuously incubating MCF-7 cells with 4-OH-tamoxifen. We found that melanoma cell adhesion molecule (MCAM/CD146), a unique epithelial-to-mesenchymal transition (EMT) inducer, was significantly up-regulated at both mRNA and protein levels in MCF-7-Tam-R cells compared to parental MCF-7 cells. Mechanistic research demonstrated that MCAM promotes tamoxifen resistance by transcriptionally suppressing ERα expression and activating the AKT pathway, followed by induction of EMT. Elevated MCAM expression was inversely correlated with recurrence-free and distant metastasis-free survival in a cohort of 4142 patients with breast cancer derived from a public database, particularly in the subgroup only treated with tamoxifen. These results demonstrate a novel function of MCAM in conferring tamoxifen resistance in breast cancer. Targeting MCAM might be a promising therapeutic strategy to overcome tamoxifen resistance in breast cancer patients.

Notch3 Maintains Luminal Phenotype and Suppresses Tumorigenesis and Metastasis of Breast Cancer via Trans-Activating Estrogen Receptor-α

The luminal A phenotype is the most common breast cancer subtype and is characterized by estrogen receptor α expression (ERα). Identification of the key regulator that governs the luminal phenotype of breast cancer will clarify the pathogenic mechanism and provide novel therapeutic strategies for this subtype of cancer. ERα signaling pathway sustains the epithelial phenotype and inhibits the epithelial-mesenchymal transition (EMT) of breast cancer. In this study, we demonstrate that Notch3 positively associates with ERα in both breast cancer cell lines and human breast cancer tissues. We found that overexpression of Notch3 intra-cellular domain, a Notch3 active form (N3ICD), in ERα negative breast cancer cells re-activated ERα, while knock-down of Notch3 reduced ERα transcript and proteins, with alteration of down-stream genes, suggesting its ability to regulate ERα. Mechanistically, our results show that Notch3 specifically binds to the CSL binding element of the ERα promoter and activates ERα expression. Moreover, Notch3 suppressed EMT, while suppression of Notch3 promoted EMT in cellular assay. Overexpressing N3ICD in triple-negative breast cancer suppressed tumorigenesis and metastasis in vivo. Conversely, depletion of Notch3 in luminal breast cancer promoted metastasis in vivo. Furthermore, Notch3 transcripts were significantly associated with prolonged relapse-free survival in breast cancer, in particular in ERα positive breast cancer patients. Our observations demonstrate that Notch3 governs the luminal phenotype via trans-activating ERα expression in breast cancer. These findings delineate the role of a Notch3/ERα axis in maintaining the luminal phenotype and inhibiting tumorigenesis and metastasis in breast cancer, providing a novel strategy to re-sensitize ERα negative or low-expressing breast cancers to hormone therapy.

Targeting Notch degradation system provides promise for breast cancer therapeutics

Notch receptor signaling pathways play an important role, not only in normal breast development but also in breast cancer development and progression. As a group of ligand-induced proteins, different subtypes of mammalian Notch (Notch1-4) are sensitive to subtle changes in protein levels. Thus, a clear understanding of mechanisms of Notch protein turnover is essential for understanding normal and pathological mechanisms of Notch functions. It has been suggested that there is a close relationship between the carcinogenesis and the dysregulation of Notch degradation. However, this relationship remains mostly undefined in the context of breast cancer, as protein degradation is mediated by numerous signaling pathways as well as certain molecule modulators (activators/inhibitors). In this review, we summarize the published data regarding the regulation of Notch family member degradation in breast cancer, while emphasizing areas that are likely to provide new therapeutic modalities for mechanism-based anti-cancer drugs.