Increased Wnt signaling triggers oncogenic conversion of human breast epithelial cells by a Notch-dependent mechanism

Targeting DLL3: Innovative Strategies for Tumor Treatment

Delta-like 3 (DLL3) is an oncogenic protein aberrantly expressed in several tumors, particularly in small-cell lung cancer. DLL3-targeted therapies have recently made significant progress, demonstrating promising preclinical and clinical efficacy. This review aims to explore the mechanisms, challenges, and future opportunities associated with therapies targeting DLL3 for cancer treatment. The biological characteristics of DLL3 and its role in the Notch signaling pathway are introduced first, delving into the role of DLL3 in tumorigenesis and cancer progression. Next, current therapeutic approaches targeting DLL3 are described, including antibody-drug conjugates, T cell engagers, chimeric antigen receptor T cells, and radiopharmaceutical therapy, highlighting their effectiveness and safety in clinical trials. Despite the promising prospects, difficulties remain in the use of DLL3 as a therapeutic target due to tumor heterogeneity, the development of resistance, potential adverse effects, and barriers to patient stratification. Therefore, the potential of combination therapies, the use of innovative drug delivery systems, and ongoing clinical trial advancements are also discussed. Finally, the potential of DLL3-targeted therapies is summarized, highlighting the importance of multidisciplinary research to guide the clinical application and optimization of this emerging treatment strategy. These approaches might provide new therapeutic options, potentially starting a new era in cancer treatment.

Wnt signaling pathways in biology and disease: mechanisms and therapeutic advances

The Wnt signaling pathway is critically involved in orchestrating cellular functions such as proliferation, migration, survival, and cell fate determination during development. Given its pivotal role in cellular communication, aberrant Wnt signaling has been extensively linked to the pathogenesis of various diseases. This review offers an in-depth analysis of the Wnt pathway, detailing its signal transduction mechanisms and principal components. Furthermore, the complex network of interactions between Wnt cascades and other key signaling pathways, such as Notch, Hedgehog, TGF-β, FGF, and NF-κB, is explored. Genetic mutations affecting the Wnt pathway play a pivotal role in disease progression, with particular emphasis on Wnt signaling's involvement in cancer stem cell biology and the tumor microenvironment. Additionally, this review underscores the diverse mechanisms through which Wnt signaling contributes to diseases such as cardiovascular conditions, neurodegenerative disorders, metabolic syndromes, autoimmune diseases, and cancer. Finally, a comprehensive overview of the therapeutic progress targeting Wnt signaling was given, and the latest progress in disease treatment targeting key components of the Wnt signaling pathway was summarized in detail, including Wnt ligands/receptors, β-catenin destruction complexes, and β-catenin/TCF transcription complexes. The development of small molecule inhibitors, monoclonal antibodies, and combination therapy strategies was emphasized, while the current potential therapeutic challenges were summarized. This aims to enhance the current understanding of this key pathway.

Understanding Susceptibility to Breast Cancer: From Risk Factors to Prevention Strategies

Breast cancer is the most common malignancy among women globally, with incidence rates continuing to rise. A comprehensive understanding of its risk factors and the underlying biological mechanisms that drive tumor initiation is essential for developing effective prevention strategies. This review examines key non-modifiable risk factors, such as genetic predisposition, demographic characteristics, family history, mammographic density, and reproductive milestones, as well as modifiable risk factors like exogenous hormone exposure, obesity, diet, and physical inactivity. Importantly, reproductive history plays a dual role, providing long-term protection while temporarily increasing breast cancer risk shortly after pregnancy. Current chemoprevention strategies primarily depend on selective estrogen receptor modulators (SERMs), including tamoxifen and raloxifene, which have demonstrated efficacy in reducing the incidence of estrogen receptor-positive breast cancer but remain underutilized due to adverse effects. Emerging approaches such as aromatase inhibitors, RANKL inhibitors, progesterone antagonists, PI3K inhibitors, and immunoprevention strategies show promise for expanding preventive options. Understanding the interactions between risk factors, hormonal influences, and tumorigenesis is critical for optimizing breast cancer prevention and advancing safer, more targeted chemopreventive interventions.

Breast Morphogenesis: From Normal Development to Cancer

The human breast gland is composed of branching epithelial ducts that culminate in milk-producing units known as terminal duct lobular units (TDLUs). The epithelial compartment comprises an inner layer of luminal epithelial cells (LEP) and an outer layer of contractile myoepithelial cells (MEP). Both LEP and MEP arise from a common stem cell population. The epithelial compartment undergoes dynamic branching morphogenesis and remodelling, which expands the surface area for milk production. The epithelial remodelling that starts at the onset of menarche is largely under hormonal control, first and foremost by estrogen and progesterone from ovaries, the production of which is stimulated by pituitary-derived hormones. Menopause leads to a significant decline in estrogen and progesterone levels, resulting in involution and senescence of the breast epithelium. The branching morphogenesis involves developmental events such as epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET). EMT and MET confer plasticity to the epithelial compartment enabling the migration of epithelial cells through the stroma and restoration of the epithelial phenotype. In the normal breast, the stroma, including the basement membrane (BM), collagen-rich extracellular matrix, and various stromal cells, supports the correct histoarchitecture of the glandular tree. However, in cancer, the stroma can acquire tumour-promoting properties and is referred to as the tumour microenvironment. This chapter will explore the developmental processes including branching morphogenesis in the normal breast gland and discuss the lineage relationship between LEPS and MEPs and their interactions with the surrounding stroma in the normal and neoplastic breast gland. Finally, we will review various in vitro and in vivo models employed in mammary gland research.

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.

Advances in new targets for immunotherapy of small cell lung cancer

Small cell lung cancer (SCLC) is one of the highly aggressive malignancies characterized by rapid growth and early metastasis, but treatment options are limited. For SCLC, carboplatin or cisplatin in combination with etoposide chemotherapy has been considered the only standard of care, but the standard first-line treatment only results in 10-month survival. The majority of patients relapse within a few weeks to months after treatment, despite the relatively sensitive response to chemotherapy. Over the past decade, immunotherapy has made significant progress in the treatment of SCLC patients. However, there have been limited improvements in survival rates for SCLC patients with the current immune checkpoint inhibitors PD-1/PD-L1 and CTLA-4. In the face of high recurrence rates, small beneficiary populations, and low survival benefits, the exploration of new targets for key molecules and signals in SCLC and the development of drugs with novel mechanisms may provide fresh hope for immunotherapy in SCLC. Therefore, the aim of this review was to explore four new targets, DLL3, TIGIT, LAG-3, and GD2, which may play a role in the immunotherapy of SCLC to find useful clues and strategies to improve the outcome for SCLC patients.

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

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

FOXO1 promotes the expression of canonical WNT target genes in examined basal-like breast and glioblastoma multiforme cancer cells

Basal-like breast cancer (BBC) and glioblastoma multiforme (GBM) are aggressive cancers associated with poor prognosis. BBC and GBM have stem cell-like gene expression signatures, which are in part driven by forkhead box O (FOXO) transcription factors. To gain further insight into the impact of FOXO1 in BBC, we treated BT549 cells with AS1842856 and performed RNA sequencing. AS1842856 binds to unphosphorylated FOXO1 and inhibits its ability to directly bind to DNA. Gene Set Enrichment Analysis indicated that a set of WNT pathway target genes, including lymphoid enhancer-binding factor 1 (LEF1) and transcription factor 7 (TCF7), were robustly induced after AS1842856 treatment. These same genes were also induced in GBM cell lines U87MG, LN18, LN229, A172, and DBTRG upon AS1842856 treatment. By contrast, follow-up RNA interference (RNAi) targeting of FOXO1 led to reduced LEF1 and TCF7 gene expression in BT549 and U87MG cells. In agreement with RNAi experiments, CRISPR Cas9-mediated FOXO1 disruption reduced the expression of canonical WNT genes LEF1 and TCF7 in U87MG cells. The loss of TCF7 gene expression in FOXO1 disruption mutants was restored by exogenous expression of the DNA-binding-deficient FOXO1-H215R. Therefore, FOXO1 induces TCF7 in a DNA-binding-independent manner, similar to other published FOXO1-activated genes such as TCF4 and hes family bHLH transcription factor 1. Our work demonstrates that FOXO1 promotes canonical WNT gene expression in examined BBC and GBM cells, similar to results found in Drosophila melanogaster, T-cell development, and murine acute myeloid leukemia models.

Anaplastic large cell lymphomas with the 6p25.3 rearrangement are a heterogeneous group of tumours with a diverse molecular background

ALK-negative anaplastic large cell lymphoma (ALCL) cases with 6p25.3 rearrangement are characterized by peculiar morphological and immunohistochemical features compare to 6p25.3-negative ALK-negative ALCL cases. A subgroup of 6p25.3-positive ALK-negative ALCL cases show the t(6,7) (p25.3;q32.3) rearrangement. Aims: To analyse the differences between 6p25.3-rearranged cases with and without t(6,7) (p25.3;q32.3). Using RNA-sequencing we studied a series of 17 samples showing 6p25.3-rearrangement, identified by FISH, consisting of seven systemic and eight primary cutaneous cases including two examples of secondary skin involvement by systemic ALCL. RNA-sequencing exclusively detected a translocation involving a gene in the 6p25.3 region (either IRF4 or DUSP22) in 7/14 cases (50%). In six of these seven cases the partner proved to be the LINC-PINT region in chromosome 7, while an EXOC2::DUSP22 rearrangement was found in one case. All cases but one were primary cutaneous ALCLs. They all were CD3 positive and BCL2 negative, while most of them expressed p-STAT3. On the contrary, cases without the t(6,7) (p25.3;q32.3) were mainly systemic (71%, 5/7) against just two pcALCL. In general, they lose CD3 (50% positive) and p-STAT3 (25% positive) expression, being all of them BCL2 positive. Moreover, in 60% of them other gene fusions were found. At the transcriptional level, they were characterized by the overexpression of TCF3 (TCF7L1/E2A), DLL3, CD58 and BCL2 genes 75%(6/8) of pcALCL with 6p25.3 rearrangement featured the so-called "biphasic morphologic pattern, which was not found in cutaneous involvement from systemic ALCL. 83% (5/6) of the pcALCL cases with the "biphasic morphologic pattern" showed the t(6,7) (p25.3;q32.3) rearrangement. ALK-negative ALCL cases with 6p25.3 rearrangement are a subgroup of tumours that are heterogeneous with respect to the presence or absence of the t(6,7) (p25.3;q32.3) translocation.

Identification of DLL3-related genes affecting the prognosis of patients with colon adenocarcinoma

Background: Delta-like ligand 3 (DLL3) is one of the NOTCH family of ligands, which plays a pro- or anti-carcinogenic role in some cancers. But the role of DLL3 in colon adenocarcinoma (COAD) has not been studied in depth. Materials and methods: First, we used Kaplan-Meier (K-M) curve to evaluate the effect of DLL3 on the prognosis of COAD in The Cancer Genome Atlas (TCGA), which was further validated in clinical samples for immunohistochemistry. Then we screened for differentially expressed genes (DEGs) of DLL3 by analyzing datasets of COAD samples from Gene Expression Omnibus (GEO) and TCGA. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, and Gene Set Enrichment Analysis (GSEA) were conducted to explore the underlying mechanisms of DLL3-related in the development and prognosis of COAD. On the basis of DLL3-related signature genes, a prognostic model and a nomogram were constructed. Finally, CIBERSORT was applied to assess the proportion of immune cell types in COAD sample. Results: Survival analysis showed a significant difference in overall survival between high- and low-expression group (p = 0.0092), with COAD patients in the high-group having poorer 5-year survival rate. Gene functional enrichment analysis revealed that DLL3-related DEGs were mainly enriched in tumor- and immunity-related signaling pathways, containing AMPK pathway and mitophagy-animal. The comparison of COAD tumor and normal, DLL3 high- and low-expression groups by GSEA found that AMPK signaling pathway and mitophagy-animal were inhibited. Nomogram constructed from DLL3-related signature genes had a good predictive effect on the prognosis of COAD. We found the highest correlation between DLL3 and interstitial dendritic cell (iDC), natural killer (NK) cell and Interstitial dendritic cell (Tem). DLL3 was also revealed to be diagnostic for COAD. In clinical sample, we identified higher DLL3 expression in colon cancer tissue than in adjacent control (p < 0.0001) and in metastasis than in primary lesion (p = 0.0056). DLL3 expression was associated with stage and high DLL3 expression was observed to predict poorer overall survival (p = 0.004). Conclusion: It suggested that DLL3 may offer prognostic value and therapeutic potential for individualized treatment of COAD, and that it may has a diagnostic role in COAD.

LIN28 and histone H3K4 methylase induce TLR4 to generate tumor-initiating stem-like cells

Chemoresistance and plasticity of tumor-initiating stem-like cells (TICs) promote tumor recurrence and metastasis. The gut-originating endotoxin-TLR4-NANOG oncogenic axis is responsible for the genesis of TICs. This study investigated mechanisms as to how TICs arise through transcriptional, epigenetic, and post-transcriptional activation of oncogenic TLR4 pathways. Here, we expressed constitutively active TLR4 (caTLR4) in mice carrying pLAP-tTA or pAlb-tTA, under a tetracycline withdrawal-inducible system. Liver progenitor cell induction accelerated liver tumor development in caTLR4-expressing mice. Lentiviral shRNA library screening identified histone H3K4 methylase SETD7 as central to activation of TLR4. SETD7 combined with hypoxia induced TLR4 through HIF2 and NOTCH. LIN28 post-transcriptionally stabilized TLR4 mRNA via de-repression of let-7 microRNA. These results supported a LIN28-TLR4 pathway for the development of HCCs in a hypoxic microenvironment. These findings not only advance our understanding of molecular mechanisms responsible for TIC generation in HCC, but also represent new therapeutic targets for the treatment of HCC.

Implications of Axis Inhibition Protein 2 in Breast Cancer Progression

BACKGROUND/AIM

Although axis inhibition protein 2 (Axin2) has been reported to act as a tumour suppressor, recent findings suggest that it exhibits oncogenic effects by mediating Snail1-induced epithelial-mesenchymal transition (EMT) in breast cancer cells. EMT is a crucial biological process involved in the initiation of metastasis in cancer progression. This study elucidated the biological significance and mechanism of Axin2 in breast cancer using transcriptomic and molecular techniques.

MATERIALS AND METHODS

The expression of Axin2 and Snail1 in MDA-MB-231 breast cancer cells was determined by western blotting analysis, and the role of Axin2 in breast cancer tumorigenesis was investigated in xenograft mouse models constructed using pLKO-Tet-shAxin2-transfected triple negative (TN) breast cancer cells. Additionally, the expression levels of EMT markers were determined using qRT-PCR, and clinical data were analysed using Kaplan-Meier (KM) plotter and The Cancer Genome Atlas (TCGA).

RESULTS

Axin2 knockdown significantly decreased (p<0.001) the proliferation of MDA-MB-231 cells in vitro and attenuated (p<0.05) the tumorigenic potential of the cells in vivo. Moreover, Axin2 knockdown significantly increased the relative mRNA levels of epithelial markers but decreased the expression of mesenchymal markers in MDA-MB-231 cells.

CONCLUSION

Axin2 may be involved in the progression of breast cancer, particularly triple-negative breast cancer, through the regulation of Snail1-induced EMT, making it a potential therapeutic target.

A genome-wide cell-free DNA methylation analysis identifies an episignature associated with metastatic luminal B breast cancer

Breast cancers of the luminal B subtype are frequent tumors with high proliferation and poor prognosis. Epigenetic alterations have been found in breast tumors and in biological fluids. We aimed to profile the cell-free DNA (cfDNA) methylome of metastatic luminal B breast cancer (LBBC) patients using an epigenomic approach to discover potential noninvasive biomarkers. Plasma cfDNA was analyzed using the Infinium MethylationEpic array in a cohort of 14 women, including metastatic LBBC patients and nontumor controls. The methylation levels of cfDNA and tissue samples were validated with droplet digital PCR. The methylation and gene expression data of 582 primary luminal breast tumors and 79 nontumor tissues were obtained from The Cancer Genome Atlas (TCGA). We found an episignature of 1,467 differentially methylated CpGs that clearly identified patients with LBBC. Among the genes identified, the promoter hypermethylation of WNT1 was validated in cfDNA, showing an area under the ROC curve (AUC) of 0.86 for the noninvasive detection of metastatic LBBC. Both paired cfDNA and primary/metastatic breast tumor samples showed hypermethylation of WNT1. TCGA analysis revealed significant WNT1 hypermethylation in the primary tumors of luminal breast cancer patients, with a negative association between WNT1 methylation and gene expression. In this proof-of-principle study, we discovered an episignature associated with metastatic LBBC using a genome-wide cfDNA methylation approach. We also identified the promoter hypermethylation of WNT1 in cfDNA as a potential noninvasive biomarker for luminal breast cancer. Our results support the use of EPIC arrays to identify new epigenetic noninvasive biomarkers 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.

The role of epigenetic modifications in drug resistance and treatment of breast cancer

Background

Breast cancer is defined as a biological and molecular heterogeneous disorder that originates from breast cells. Genetic predisposition is the most important factor giving rise to this malignancy. The most notable mutations in breast cancer occur in the BRCA1 and BRCA2 genes. Owing to disease heterogeneity, lack of therapeutic target, anti-cancer drug resistance, residual disease, and recurrence, researchers are faced with challenges in developing strategies to treat patients with breast cancer.

Results

It has recently been reported that epigenetic processes such as DNA methylation and histone modification, as well as microRNAs (miRNAs), have potently contributed to the pathophysiology, diagnosis, and treatment of breast cancer. These observations have persuaded researchers to move their therapeutic approaches beyond the genetic framework toward the epigenetic concept.

Conclusion

Herein we discuss the molecular and epigenetic mechanisms underlying breast cancer progression and resistance as well as various aspects of epigenetic-based therapies as monotherapy and combined with immunotherapy.

Wnt Signaling in the Breast: From Development to Disease

The Wnt cascade is a primordial developmental signaling pathway that plays a myriad of essential functions throughout development and adult homeostasis in virtually all animal species. Aberrant Wnt activity is implicated in embryonic and tissue morphogenesis defects, and several diseases, most notably cancer. The role of Wnt signaling in mammary gland development and breast cancer initiation, maintenance, and progression is far from being completely understood and is rather shrouded in controversy. In this review, we dissect the fundamental role of Wnt signaling in mammary gland development and adult homeostasis and explore how defects in its tightly regulated and intricated molecular network are interlinked with cancer, with a focus on the breast.

Research progress on RNA‑binding proteins in breast cancer (Review)

Breast cancer is the most common malignancy among women, and the abnormal regulation of gene expression serves an important role in its occurrence and development. However, the molecular mechanisms underlying gene expression are highly complex and heterogeneous, and RNA-binding proteins (RBPs) are among the key regulatory factors. RBPs bind targets in an environment-dependent or environment-independent manner to influence mRNA stability and the translation of genes involved in the formation, progression, metastasis and treatment of breast cancer. Due to the growing interest in these regulators, the present review summarizes the most influential studies concerning RBPs associated with breast cancer to elucidate the role of RBPs in breast cancer and to assess how they interact with other key pathways to provide new molecular targets for the diagnosis and treatment of breast cancer.

Elevated DLL3 in stomach cancer by tumor-associated macrophages enhances cancer-cell proliferation and cytokine secretion of macrophages

Background

The notch signal pathway is important in the development of both tumor-associated macrophages (TAMs) and stomach cancer, but how Notch signaling affects TAMs in stomach cancer is barely understood.

Methods

The expressions of Notch1, Notch2, Notch3, Notch4, hes family bHLH transcription factor 1 (Hes1), and delta-like canonical Notch ligand 3 (DLL3) were detected by Western blot and the expressions of interleukin (IL)-10, IL-12, and IL1-β were detected using enzyme-linked immunosorbent assay after the co-culture of macrophages and stomach-cancer cells. The proliferation and migration of cancer cells were detected using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and scratch assay, respectively, and the cell cycle was detected using Annexin V/propidium iodide assay. The protein interactions with DLL3 were detected using co-immunoprecipitation and mass spectrometry.

Results

The co-culture of macrophages and stomach-cancer cells MKN45 and BGC823 could enhance cell proliferation accompanied by the activation of Notch1/Notch2 signaling and upregulation of DLL3. Notch signaling gamma-secretase inhibitor (DAPT) blocked this process. The overexpression of DLL3 in stomach-cancer cells could promote the proliferation of cancer cells, enhance the activation of Notch1/Notch2 signaling, induce the expression of IL-33, lead to the degradation of galectin-3–binding protein (LG3BP) and heat shock cognate 71 kDa protein (HSPA8), and result in elevated IL-1β, IL-12, and IL-10 secretion by macrophages. Higher expression of DLL3 or IL-33 could lead to a lower survival rate based on University of California, Santa Cruz Xena Functional Genomics Explorer and The Cancer Genome Atlas data set.

Conclusions

This is evidence that DLL3 regulates macrophages in stomach cancer, suggesting that DLL3 may be a novel and potential target for stomach-cancer therapy.

Mammary Development and Breast Cancer: a Notch Perspective

Mammary gland development primarily occurs postnatally, and this unique process is complex and regulated by systemic hormones and local growth factors. The mammary gland is also a highly dynamic organ that undergoes profound changes at puberty and during the reproductive cycle. These changes are driven by mammary stem cells (MaSCs). Breast cancer is one of the most common causes of cancer-related death in women. Cancer stem cells (CSCs) play prominent roles in tumor initiation, drug resistance, tumor recurrence, and metastasis. The highly conserved Notch signaling pathway functions as a key regulator of the niche mediating mammary organogenesis and breast neoplasia. In this review, we discuss mechanisms by which Notch contributes to breast carcinoma pathology and suggest potentials for therapeutic targeting of Notch in breast cancer. In summary, we provide a comprehensive overview of Notch functions in regulating MaSCs, mammary development, and breast cancer.

Notch Signalling in Breast Development and Cancer

The Notch signalling pathway is a highly conserved developmental signalling pathway, with vital roles in determining cell fate during embryonic development and tissue homeostasis. Aberrant Notch signalling has been implicated in many disease pathologies, including cancer. In this review, we will outline the mechanism and regulation of the Notch signalling pathway. We will also outline the role Notch signalling plays in normal mammary gland development and how Notch signalling is implicated in breast cancer tumorigenesis and progression. We will cover how Notch signalling controls several different hallmarks of cancer within epithelial cells with sections focussed on its roles in proliferation, apoptosis, invasion, and metastasis. We will provide evidence for Notch signalling in the breast cancer stem cell phenotype, which also has implications for therapy resistance and disease relapse in breast cancer patients. Finally, we will summarise the developments in therapeutic targeting of Notch signalling, and the pros and cons of this approach for the treatment of breast cancer.

Delta-like canonical Notch ligand 3 as a potential therapeutic target in malignancies: A brief overview

Delta‐like canonical Notch ligand 3 (DLL3) is a member of the Delta/Serrate/Lag2 (DSL) Notch receptor ligand family and plays a crucial role in Notch signaling, which influences various cellular processes including differentiation, proliferation, survival, and apoptosis. DLL3 is expressed throughout the presomitic mesoderm and is localized to the rostral somatic compartments; mutations in DLL3 induce skeletal abnormalities such as spondylocostal dysostosis. Recently, DLL3 has attracted interest as a novel molecular target due to its high expression in neuroendocrine carcinoma of the lung. Moreover, a DLL3‐targeting Ab‐drug conjugate, rovalpituzumab tesirine (ROVA‐T), has been developed as a new treatment with proven antitumor activity. However, the development of ROVA‐T was suspended because of shorter overall survival compared to topotecan, the second‐line standard treatment. Thus, several studies on the mechanism and function of DLL3 in several malignancies are underway to find a new strategy for targeting DLL3. In this review, we discuss the roles of DLL3 in various malignancies and the future perspectives of DLL3‐related research, especially as a therapeutic target.

Heat Killed Salmonella typhimurium Protects Intestine Against Radiation Injury Through Wnt Signaling Pathway

Gastrointestinal (GI) toxicity caused by ionizing radiation (IR) is a dose limiting factor in radiotherapy and a great threat for individual nuclear-related military missions. However, there are currently no available strategies to effectively prevent the damage on the intestine induced by IR. In the present study, the protective activity of Heat Killed Salmonella typhimurium (HKST) on intestine against IR was investigated. Through mouse intestinal organoids and whole body irradiation of mice, we found that the pretreatment with HKST significantly preserved the structure of small intestine upon IR exposure and promoted the proliferation of intestinal cells post-IR. Further study revealed that the radioprotective effects of HKST were involved in DNA damage response (DDR) signaling. Moreover, the stimulation of DDR signaling by HKST upon radiation damage was mediated by Wnt signaling, in which the inhibition of Wnt signaling diminished the radioprotective effects of HKST. To sum up, our study suggested HKST as a potential radioprotectant used for prevention of IR-induced GI toxicity.

Chlorpyrifos induces cell proliferation in MCF-7 and MDA-MB-231 cells, through cholinergic and Wnt/β-catenin signaling disruption, AChE-R upregulation and oxidative stress generation after single and repeated treatment

Chlorpyrifos (CPF) biocide, is associated with breast cancer. The processes underlying this association have not been elucidated to date. CPF increases MCF-7 and MDA-MB-231 cell proliferation after acute and long-term treatment, partially through KIAA1363 overexpression and aryl-hydrocarbon receptor activation but also through estrogen receptor-alpha activation after 24 h exposure in MCF-7 cells, suggesting other mechanisms may be involved. CPF induces reactive oxygen species (ROS) generation, acetylcholine accumulation, and overexpression of acetylcholinesterase-R/S (AChE-R/S) variants, while it also alters the Wnt/β-catenin pathway, both in vitro and in vivo, in processes different from cancer. These latter mechanisms are also linked to cell proliferation and could mediate this effect induced by CPF. Our results show that CPF (0.01-100 μM), following one-day and fourteen-days treatment, respectively, induced ROS generation and lipid peroxidation, and acetylcholine accumulation due to AChE inhibition, Wnt/β-catenin up- or downregulation depending on the CPF treatment concentration, and AChE-R and AChE-S overexpression, with the latter being mediated through GSK-3β activity alteration. Finally, CPF promoted cell division through ACh and ROS accumulation, AChE-R overexpression, and Wnt/β-catenin signaling disruption. Our results provide novel information on the effect of CPF on human breast cancer cell lines that may help to explain its involvement in breast cancer.

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.

Progesterone Receptor Signaling in the Breast Tumor Microenvironment

The tumor microenvironment (TME) is a complex infrastructure composed of stromal, epithelial, and immune cells embedded in a vasculature ECM. The microenvironment surrounding mammary epithelium plays a critical role during the development and differentiation of the mammary gland, enabling the coordination of the complex multihormones and growth factor signaling processes. Progesterone/progesterone receptor paracrine signaling interactions in the microenvironment play vital roles in stem/progenitor cell function during normal breast development. In breast cancer, the female sex hormones, estrogen and progesterone, and growth factor signals are altered in the TME. Progesterone signaling modulates not only breast tumors but also the breast TME, leading to the activation of a series of cross-communications that are implicated in the genesis of breast cancers. This chapter reviews the evidence that progesterone and PR signaling modulates not only breast epitheliums but also the breast TME. Furthermore, crosstalk between estrogen and progesterone signaling affecting different cell types within the TME is discussed. A better understanding of how PR and progesterone affect the TME of breast cancer may lead to novel drugs or a therapeutic approach for the treatment of breast cancer shortly.

Inhibition of the Wnt Signalling Pathway: An Avenue to Control Breast Cancer Aggressiveness

Breast cancer (BC) is the most common tumour in women. Although the introduction of novel therapeutic approaches in clinical practice has dramatically improved the clinical outcome of BC patients, this malignant disease remains the second leading cause of cancer-related death worldwide. The wingless/integrated (Wnt) signalling pathway represents a crucial molecular node relevantly implicated in the regulation of normal somatic stem cells as well as cancer stem cell (CSC) traits and the epithelial-mesenchymal transition cell program. Accordingly, Wnt signalling is heavily dysregulated in BC, and the altered expression of different Wnt genes is significantly associated with cancer-related aggressive behaviours. For all these reasons, Wnt signalling represents a promising therapeutic target currently under clinical investigation to achieve cancer eradication by eliminating CSCs, considered by most to be responsible for tumour initiation, relapse, and drug resistance. In this review, we summarized the current knowledge on the Wnt signalling pathway in BC and have presented evidence implicating the suitability of Wnt targeting in an attempt to improve the outcome of patients without affecting the normal somatic stem cell population.

Wnt signaling in breast cancer: biological mechanisms, challenges and opportunities

Wnt signaling is a highly conserved signaling pathway that plays a critical role in controlling embryonic and organ development, as well as cancer progression. Genome-wide sequencing and gene expression profile analyses have demonstrated that Wnt signaling is involved mainly in the processes of breast cancer proliferation and metastasis. The most recent studies have indicated that Wnt signaling is also crucial in breast cancer immune microenvironment regulation, stemness maintenance, therapeutic resistance, phenotype shaping, etc. Wnt/β-Catenin, Wnt-planar cell polarity (PCP), and Wnt-Ca2+ signaling are three well-established Wnt signaling pathways that share overlapping components and play different roles in breast cancer progression. In this review, we summarize the main findings concerning the relationship between Wnt signaling and breast cancer and provide an overview of existing mechanisms, challenges, and potential opportunities for advancing the therapy and diagnosis of breast cancer.

The Relevance of Notch Signaling in Cancer Progression

The Notch signaling pathway controls normal embryonic development and tissue homeostasis of many cell types. It regulates cell proliferation, fate, differentiation, and cell death by short-range signaling between nearby cells that come in contact. The Notch pathway has also been critically involved in the pathobiology of a variety of malignancies, regulating cancer initiation and development, as well as early stages of cancer progression, by adjusting conserved cellular programs. Fibroblasts, an essential for tumor growth component of stroma, have also been affected by Notch regulation. Sequencing Notch gene mutations have been identified in a number of human tumors, revealing information on the progression of specific cancer types, such as ovarian cancer and melanoma, immune-associated tumors such as myeloid neoplasms, but especially in lymphocytic leukemia. Activation of the Notch can be either oncogenic or it may contain growth-suppressive functions, acting as a tumor suppressor in other hematopoietic cells, hepatocytes, skin, and pancreatic epithelium.

Notch in Head and Neck Cancer

Head and neck cancer is a group of neoplastic diseases affecting the facial, oral, and neck region. It is one of the most common cancers worldwide with an aggressive, invasive evolution. Due to the heterogeneity of the tissues affected, it is particularly challenging to study the molecular mechanisms at the basis of these tumors, and to date we are still lacking accurate targets for prevention and therapy. The Notch signaling is involved in a variety of tumorigenic mechanisms, such as regulation of the tumor microenvironment, aberrant intercellular communication, and altered metabolism. Here, we provide an up-to-date review of the role of Notch in head and neck cancer and draw parallels with other types of solid tumors where the Notch pathway plays a crucial role in emergence, maintenance, and progression of the disease. We therefore give a perspective view on the importance of the pathway in neoplastic development in order to define future lines of research and novel therapeutic approaches.

Targeting Notch Trafficking and Processing in Cancers

The Notch family comprises a group of four ligand-dependent receptors that control evolutionarily conserved developmental and homeostatic processes and transmit signals to the microenvironment. NOTCH undergoes remodeling, maturation, and trafficking in a series of post-translational events, including glycosylation, ubiquitination, and endocytosis. The regulatory modifications occurring in the endoplasmic reticulum/Golgi precede the intramembrane γ-secretase proteolysis and the transfer of active NOTCH to the nucleus. Hence, NOTCH proteins coexist in different subcellular compartments and undergo continuous relocation. Various factors, including ion concentration, enzymatic activity, and co-regulatory elements control Notch trafficking. Interfering with these regulatory mechanisms represents an innovative therapeutic way to bar oncogenic Notch signaling. In this review, we briefly summarize the role of Notch signaling in cancer and describe the protein modifications required for NOTCH to relocate across different subcellular compartments. We focus on the functional relationship between these modifications and the corresponding therapeutic options, and our findings could support the development of trafficking modulators as a potential alternative to the well-known γ-secretase inhibitors.

Novel strategies to target chemoresistant triple-negative breast cancer

Previous studies from our group and others have shown that current drug treatment(s) strategies eliminate bulk of tumor cells (non-CSCs) but it had a minimal effect on cancer stem cells (CSCs) leading to resistance and tumor recurrence. We studied the effects of CFM-4.16 (CARP-1 functional mimetic) and/or cisplatin on four Triple-negative breast cancer (TNBC) MDA-MB-468, MDA-MB-231, CRL-2335 and BR-1126, two cisplatin resistant CisR/MDA-231 and CisR/MDA-468 and cancer stem cells (CSCs) from resistant cell lines. TNBC cells treated with CFM-4.16 plus cisplatin inhibited the expression of FZD8, LRP6 and c-Myc and significantly enhanced cell death in all the cell lines by ~70%-80% compared with the control(s). When Cisplatin resistant CisR/MDA-231 and CisR/MDA-468 were treated with CFM-4.16 plus cisplatin, they also showed a reduction in FZD8 and LRP6 and increased apoptosis compared to control group. Similarly, CFM-4.16 plus cisplatin treatment reduced mammospheres formation abilities of CSCs by 80-90% compared to control group, increased PARP cleavage and apoptosis. Data shows CFM-4.16 plus cisplatin treatment significantly increased apoptosis/cell death in parental, cisplatin resistant and CSCs. Taken together the data suggests that FZD8-mediated Wnt-signaling plays a major role in mediating CSCs growth and resistance to chemotherapy and its inhibition enhances the chemotherapeutic response in TNBC.

Prevention of tumor risk associated with the reprogramming of human pluripotent stem cells

Human pluripotent embryonic stem cells have two special features: self-renewal and pluripotency. It is important to understand the properties of pluripotent stem cells and reprogrammed stem cells. One of the major problems is the risk of reprogrammed stem cells developing into tumors. To understand the process of differentiation through which stem cells develop into cancer cells, investigators have attempted to identify the key factors that generate tumors in humans. The most effective method for the prevention of tumorigenesis is the exclusion of cancer cells during cell reprogramming. The risk of cancer formation is dependent on mutations of oncogenes and tumor suppressor genes during the conversion of stem cells to cancer cells and on the environmental effects of pluripotent stem cells. Dissecting the processes of epigenetic regulation and chromatin regulation may be helpful for achieving correct cell reprogramming without inducing tumor formation and for developing new drugs for cancer treatment. This review focuses on the risk of tumor formation by human pluripotent stem cells, and on the possible treatment options if it occurs. Potential new techniques that target epigenetic processes and chromatin regulation provide opportunities for human cancer modeling and clinical applications of regenerative medicine.

PEX5, a novel target of microRNA-31-5p, increases radioresistance in hepatocellular carcinoma by activating Wnt/β-catenin signaling and homologous recombination

Rationale: Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death worldwide, with high recurrence and metastasis rates. Although radiation is an effective treatment for tumors, it is often limited by intrinsic radioresistance in HCC. The contributions of dysregulated microRNAs, including miR-31-5p, to HCC progression have been recently reported. However, the role of miR-31-5p in the radiation response of HCC is unknown. In this study, we aimed to investigate the impact of miR-31-5p on HCC radiosensitivity.

Methods: miR-31-5p expression in HCC tissues, paired adjacent tissues, and HCC cell lines was measured using quantitative real-time polymerase chain reaction and in situ hybridization. Bioinformatic analyses, gain- and loss-of-function experiments, and luciferase reporter assays were performed to validate peroxisomal biogenesis factor 5 (PEX5) as a direct target of miR-31-5p. The biofunctions of PEX5 and miR-31-5p in HCC were determined by Transwell, wound-healing, and Cell Counting Kit-8 (CCK8) assays. A colony formation assay was used to evaluate the radiosensitivity of HCC cells. The interaction among PEX5, β-catenin, Rac1, and JNK-2 was confirmed by coimmunoprecipitation. A xenograft tumor model was established to validate the effects of miR-31-5p and PEX5 on HCC progression and radiosensitivity in vivo.

Results: Low expression of miR-31-5p in HCC specimens, as observed in this study, predicted a poor clinical outcome. However, the expression pattern of PEX5, as a direct target of miR-31-5p, was opposite that of miR-31-5p, and high PEX5 expression indicated poor prognosis in HCC patients. Ectopic expression of PEX5 increased the proliferation, migration, and invasion abilities and enhanced the radioresistance of HCC cells in vitro and in vivo; however, these phenotypes were inhibited by miR-31-5p. Mechanistically, PEX5 stabilized cytoplasmic β-catenin and facilitated β-catenin nuclear translocation to activate Wnt/β-catenin signaling. Moreover, upon radiation exposure, PEX5 reduced excessive reactive oxygen species (ROS) accumulation and activated the homologous recombination (HR) pathway, which protected HCC cells from radiation-induced damage.

Conclusions: Our findings demonstrated a novel role for PEX5 as a miR-31-5p target and a mediator of the Wnt/β-catenin signaling and HR pathways, providing new insights into studying HCC radiation responses and implicating PEX5 and miR-31-5p as potential therapeutic targets in HCC.

Aberrant WNT/CTNNB1 Signaling as a Therapeutic Target in Human Breast Cancer: Weighing the Evidence

WNT signaling is crucial for tissue morphogenesis during development in all multicellular animals. After birth, WNT/CTNNB1 responsive stem cells are responsible for tissue homeostasis in various organs and hyperactive WNT/CTNNB1 signaling is observed in many different human cancers. The first link between WNT signaling and breast cancer was established almost 40 years ago, when Wnt1 was identified as a proto-oncogene capable of driving mammary tumor formation in mice. Since that discovery, there has been a dedicated search for aberrant WNT signaling in human breast cancer. However, much debate and controversy persist regarding the importance of WNT signaling for the initiation, progression or maintenance of different breast cancer subtypes. As the first drugs designed to block functional WNT signaling have entered clinical trials, many questions about the role of aberrant WNT signaling in human breast cancer remain. Here, we discuss three major research gaps in this area. First, we still lack a basic understanding of the function of WNT signaling in normal human breast development and physiology. Second, the overall extent and precise effect of (epi)genetic changes affecting the WNT pathway in different breast cancer subtypes are still unknown. Which underlying molecular and cell biological mechanisms are disrupted as a result also awaits further scrutiny. Third, we survey the current status of targeted therapeutics that are aimed at interfering with the WNT pathway in breast cancer patients and highlight the importance and complexity of selecting the subset of patients that may benefit from treatment.

Shaping of the Tumor Microenvironment by Notch Signaling

The tumor microenvironment (TME) has become a major concern of cancer research both from a basic and a therapeutic point of view. Understanding the effect of a signaling pathway-and thus the effect of its targeting-in every aspect of the microenvironment is a prerequisite to predict and analyze the effect of a therapy. The Notch signaling pathway is involved in every component of the TME as well as in the interaction between the different parts of the TME. This review aims at describing how Notch signaling is impacting the TME and the consequences this may have when modulating Notch signaling in a therapeutic perspective.

In vitro transformation of primary human hepatocytes: Epigenetic changes and stemness properties

Human hepatocarcinogenesis is a complex process with many unresolved issues, including the cell of origin (differentiated and/or progenitor/stem cells) and the initial steps leading to tumor development. With the aim of providing new tools for studying hepatocellular carcinoma initiation and progression, we developed an innovative model based on primary human hepatocytes (PHHs) lentivirus-transduced with SV40LT+ST, HRASV12 with or without hTERT. The differentiation status of these transduced-PHHs was characterized by RNA sequencing (including lncRNAs), and the expression of some differentiation markers confirmed by RT-qPCR and immunofluorescence. In addition, their transformation capacity was assessed by colony formation in soft agar and tumorigenicity evaluated in immune-deficient mice. The co-expression of SV40LT+ST and HRASV12 in PHHs, in association or not with hTERT, led to the emergence of transformed clones. These clones exhibited a poorly differentiated cell phenotype with expression of stemness and mesenchymal-epithelial transition markers and gave rise to cancer stem cell subpopulations. In vivo, they resulted in poorly differentiated hepatocellular carcinomas with a reactivation of endogenous hTERT. These experiments demonstrate for the first time that non-cycling human mature hepatocytes can be permissive to in vitro transformation. This cellular tool provides the first comprehensive in vitro model for identifying genetic/epigenetic changes driving human hepatocarcinogenesis.

DLL3 expression in large cell neuroendocrine carcinoma (LCNEC) and association with molecular subtypes and neuroendocrine profile

OBJECTIVES

For stage IV pulmonary large cell neuroendocrine carcinoma (LCNEC), the only therapeutic option is palliative chemotherapy. DLL3 is a new therapeutic target, which seems to be often expressed in SCLC and LCNEC. It has recently been reported that DLL3 mRNA expression is particularly upregulated in the LCNEC subgroup with STK11/KEAP1 and TP53 co-mutations, in contrast to lower expression levels in RB1 and TP53 co-mutated LCNEC. Our aim was to investigate DLL3 protein expression in stage IV LCNEC and correlate data with mutational profiles (i.e.STK11/KEAP1/RB1), immunostaining results (pRb, NE markers) and clinical characteristics.

MATERIALS AND METHODS

Immunohistochemical analysis for DLL3 (SC16.65) and ASCL1 (SC72.201) was performed on 94 and 51 FFPE tissue sections, respectively, of pathologically reviewed stage IV LCNEC. DLL3 and ASCL1 were scored positive if ≥1% of the tumor cells showed cytoplasmic/membranous or dotlike (DLL3) or nuclear (ASCL1) immunostaining. Data were correlated with available sequencing (TP53, RB1, STK11, KEAP1), immunostaining (pRb, NE markers) and clinical data.

RESULTS

DLL3 was expressed in 70/94 (74%) LCNEC, 56 (80%) of which showed cytoplasmic/membranous staining. Median H-score was 55 (interquartile range 0-160). DLL3 staining was not different in pRb immunohistochemistry negative and positive patients (DLL3+ in 53/70 (76%) vs. 14/21 (67%), p = 0.409) or RB1 mutated and wildtype patients (DLL3+ in 27/34 (79%) vs. 23/33 (70%), p = 0.361). Nevertheless, 6/6 (100%) STK11 mutated, 10/11 (91%) KEAP1 mutated and 9/9 (100%) TP53 wildtype tumors were DLL3+ . Furthermore, DLL3 expression was associated with expression of ASCL1 and at least 2 out of 3 neuroendocrine markers.

CONCLUSION

The high percentage (74%) of DLL3 expression in stage IV LCNEC denotes the potential of DLL3 targeted therapy in this patient group.

Downregulation of STAT3, β-Catenin, and Notch-1 by Single and Combinations of siRNA Treatment Enhance Chemosensitivity of Wild Type and Doxorubicin Resistant MCF7 Breast Cancer Cells to Doxorubicin

Combinatorial therapeutic strategies using siRNA and small molecules to eradicate tumors are emerging. Targeting multiple signaling pathways decreases the chances of cancer cells switching and adapting new signaling processes that may occur when using a single therapeutic modality. Aberrant functioning of Notch-1, Wnt/β-catenin, and STAT3 proteins and their crosstalk signaling pathways have been found to be involved in tumor survival, drug resistance, and relapse. In the current study, we describe a therapeutic potential of single and combinations of siRNA designed for silencing Notch-1, Wnt/β-catenin, and STAT3 in MCF7_DoxS (wild type) and MCF7_DoxR (doxorubicin resistant) breast cancer cells. The MCF7_DoxR cells were developed through treatment with a gradual increase in doxorubicin concentration, the expression of targeted genes was investigated, and the expression profiling of CD44/CD24 of the MCF7_DoxS and MCF7_DoxR cells were detected by flow cytometry. Both MCF7_DoxS and MCF7_DoxR breast cancer cells were treated with single and combinations of siRNA to investigate synergism and were analyzed for their effect on cell proliferation with and without doxorubicin treatment. The finding of this study showed the overexpression of targeted genes and the enrichment of the CD44⁻/CD24⁺ phenotype in MCF7_DoxR cells when compared to MCF7_DoxS cells. In both cell lines, the gene silencing efficacy showed a synergistic effect when combining STAT3/Notch-1 and STAT3/Notch-1/β-catenin siRNA. Interestingly, the chemosensitivity of MCF7_DoxS and MCF7_DoxR cells to doxorubicin was increased when combined with siRNA treatment. Our study shows the possibility of using single and combinations of siRNA to enhance the chemosensitivity of cancer cells to conventional antitumor chemotherapy.

Convergence of Wnt and Notch signaling controls ovarian cancer cell survival

In the last 40 years ovarian cancer mortality rates have slightly declined and, consequently, it continues to be the fifth cause of cancer death in women. In the present study, we showed that β-catenin signaling is involved in the functions of ovarian cancer cells and interacts with the Notch system. Wnt and Notch systems showed to be prosurvival for ovarian cancer cells and their inhibition impaired cell proliferation and migration. We also demonstrated that the inhibition of β-catenin by means of two molecules, XAV939 and ICG-001, decreased the proliferation of the IGROV1 and SKOV3 ovarian cancer cell lines and that ICG-001 increased the percentage of IGROV1 cells undergoing apoptosis. The simultaneous inhibition of β-catenin and Notch signaling, by using the DAPT inhibitor, decreased ovarian cancer cell proliferation to the same extent as targeting only the Wnt/β-catenin pathway. A similar effect was observed in IGROV1 cell migration with ICG-001 and DAPT. ICG-001 increased the Notch target genes Hes-1 and Hey-1 and increased Jagged1 expression. However, no changes were observed in Dll4 or Notch 1 and 4 expressions. Our results suggest that Notch and β-catenin signaling co-operate in ovarian cancer to ensure the proliferation and migration of cells and that this could be achieved, at least partly, by the upregulation of Notch Jagged1 ligand in the absence of Wnt signaling. We showed that the Wnt pathway crosstalks with Notch in ovarian cancer cell functions, which may have implications in ovarian cancer therapeutics.

Targeting the crosstalks of Wnt pathway with Hedgehog and Notch for cancer therapy

Wnt pathway is an evolutionarily conserved signaling pathway determining patterning of animal embryos, cell fate, cell polarity, and a substantial role in the origin and maintenance of stem cells. It has been found to crosstalk with two other major developmental pathways, Hedgehog and Notch, in many embryological development cascades and in maintaining stemness of stem cells Research has shown that all the three pathways are potent in inducing tumorigenesis, driving tumor progression and aiding epithelial to mesenchymal transition in malignant cells, apart from maintaining cancer stem cells population inside the tumor tissue. Cancer stem cells are thought to aid in the process of tumor relapse, as they survive therapy by displaying drug resistance and then repopulating tumor tissues. Hence the role of these crosstalks in cancer is under intensive research. Inhibition of all the three pathways individually have resulted in tumor regression, but not optimally, as treatment failure and cancer relapse have been found to occur. Hence, instead of targeting a single pathway, targeting the crosstalk network could be a better alternative to conventional cancer treatment. Also, elimination of both tumor cells as well as cancer stem cells implies a reduced chance of relapse. Drugs developed to target these crosstalking networks, when used in combinatorial therapy, can potentially increase the efficacy of the therapy to a very large extent.

Mathematical modeling of bone marrow - peripheral blood dynamics in the disease state based on current emerging paradigms, part II

The cancer stem cell hypothesis has gained currency in recent times but concerns remain about its scientific foundations because of significant gaps that exist between research findings and comprehensive knowledge about cancer stem cells (CSCs). In this light, a mathematical model that considers hematopoietic dynamics in the diseased state of the bone marrow and peripheral blood is proposed and used to address findings about CSCs. The ensuing model, resulting from a modification and refinement of a recent model, develops out of the position that mathematical models of CSC development, that are few at this time, are needed to provide insightful underpinnings for biomedical findings about CSCs as the CSC idea gains traction. Accordingly, the mathematical challenges brought on by the model that mirror general challenges in dealing with nonlinear phenomena are discussed and placed in context. The proposed model describes the logical occurrence of discrete time delays, that by themselves present mathematical challenges, in the evolving cell populations under consideration. Under the challenging circumstances, the steady state properties of the model system of delay differential equations are obtained, analyzed, and the resulting mathematical predictions arising therefrom are interpreted and placed within the framework of findings regarding CSCs. Simulations of the model are carried out by considering various parameter scenarios that reflect different experimental situations involving disease evolution in human hosts. Model analyses and simulations suggest that the emergence of the cancer stem cell population alongside other malignant cells engenders higher dimensions of complexity in the evolution of malignancy in the bone marrow and peripheral blood at the expense of healthy hematopoietic development. The model predicts the evolution of an aberrant environment in which the malignant population particularly in the bone marrow shows tendencies of reaching an uncontrollable equilibrium state. Essentially, the model shows that a structural relationship exists between CSCs and non-stem malignant cells that confers on CSCs the role of temporally enhancing and stimulating the expansion of non-stem malignant cells while also benefitting from increases in their own population and these CSCs may be the main protagonists that drive the ultimate evolution of the uncontrollable equilibrium state of such malignant cells and these may have implications for treatment.

Moving Breast Cancer Therapy up a Notch

Breast cancer is the second most common malignancy, worldwide. Treatment decisions are based on tumor stage, histological subtype, and receptor expression and include combinations of surgery, radiotherapy, and systemic treatment. These, together with earlier diagnosis, have resulted in increased survival. However, initial treatment efficacy cannot be guaranteed upfront, and these treatments may come with (long-term) serious adverse effects, negatively affecting a patient's quality of life. Gene expression-based tests can accurately estimate the risk of recurrence in early stage breast cancers. Disease recurrence correlates with treatment resistance, creating a major need to resensitize tumors to treatment. Notch signaling is frequently deregulated in cancer and is involved in treatment resistance. Preclinical research has already identified many combinatory therapeutic options where Notch involvement enhances the effectiveness of radiotherapy, chemotherapy or targeted therapies for breast cancer. However, the benefit of targeting Notch has remained clinically inconclusive. In this review, we summarize the current knowledge on targeting the Notch pathway to enhance current treatments for breast cancer and to combat treatment resistance. Furthermore, we propose mechanisms to further exploit Notch-based therapeutics in the treatment of breast cancer.

Notch Signaling in the Tumor Microenvironment

The Notch signaling pathway regulates many aspects of cancer biology. Most attention has been given to its role in the transformed cell. However, it is now clear that cancer progression and metastasis depend on the bidirectional interactions between cancer cells and their environment, forming the tumor microenvironment (TME). These interactions are mediated and constantly evolve through paracrine and juxtacrine signaling. In this review, we discuss how Notch signaling takes an important part in regulating the crosstalk between the different compartments of the TME. We also address the consequences of the Notch-TME involvement from a therapeutic perspective.

Inhibitor of DNA Binding 2 Inhibits Epithelial-Mesenchymal Transition via Up-Regulation of Notch3 in Breast Cancer

Breast cancer is the second leading cause of cancer death in women worldwide. Incurable metastatic breast disease presents a major clinical challenge and is the main cause of breast cancer-related death. The epithelial-mesenchymal transition (EMT) is a critical early promoter of metastasis. In the present study, we identified a novel role for the inhibitor of DNA binding 2 (Id2), a member of the basic helix-loop-helix protein family, during the EMT of breast cancer. Expression of Id2 was positively correlated with Notch3 in breast cancer cells. Low expression of Id2 and Notch3 was associated with worse distant metastasis-free survival in breast cancer patients. The present study revealed that Id2 activated Notch3 expression by blocking E2A binding to an E-box motif in the Notch3 promoter. The Id2-mediated up-regulation of Notch3 expression at both the mRNA and protein levels resulted in an attenuated EMT, which was associated with reduced motility and matrix invasion of ER-positive and -negative human breast cancer cells and the emergence of E-cadherin expression and reduction in the mesenchymal marker vimentin in triple-negative breast cancer cells. In summary, our findings identified Id2 as a suppressor of the EMT and positive transcriptional regulator of Notch3 in breast cancer. Id2 and Notch3 may serve as novel prognostic markers in a subpopulation of ER-positive breast cancer patients.

Targeting Stemness: Implications for Precision Medicine in Breast Cancer

The genomic landscape of breast cancer has been delineated in recent years. Advances in molecular characterization and targeting strategies are making it feasible to integrate clinical, genome-based and phenotype-based diagnostic and therapeutic methods and apply them to individual patient in the era of precision medicine. Cancer stem cells (CSCs) are a subpopulation in the tumor which have the capability of self-renewal and differentiation. Breast CSCs have important clinical implications as they account for tumor initiation, maintenance, metastasis, therapy resistance, and relapse. In this chapter, we will introduce approaches used to characterize breast CSCs, crucial pathways involved in regulating cancer stemness, and implications of breast CSCs in the precision diagnosis and treatment of breast cancer. We will also discuss novel compounds and therapeutic strategies that selectively target breast CSCs. Integration of breast CSC-related molecular diagnosis and targeted therapy into the clinical workflow of precision medicine has the potential to deliver more effective treatment to breast cancer patients.

The Notch Pathway in Breast Cancer Progression

Objective

Notch signaling pathway is a vital parameter of the mammalian vascular system. In this review, the authors summarize the current knowledge about the impact of the Notch signaling pathway in breast cancer progression and the therapeutic role of Notch's inhibition.

Methods

The available literature in MEDLINE, PubMed, and Scopus, regarding the role of the Notch pathway in breast cancer progression was searched for related articles from about 1973 to 2017 including terms such as “Notch,” “Breast Cancer,” and “Angiogenesis.” Results. Notch signaling controls the differentiation of breast epithelial cells during normal development. Studies confirm that the Notch pathway has a major participation in breast cancer progression through overexpression and/or abnormal genetic type expression of the notch receptors and ligands that determine angiogenesis. The cross-talk of Notch and estrogens, the effect of Notch in breast cancer stem cells formation, and the dependable Notch overexpression during breast tumorigenesis have been studied enough and undoubtedly linked to breast cancer development. The already applied therapeutic inhibition of Notch for breast cancer can drastically change the course of the disease.

Conclusion

Current data prove that Notch pathway has a major participation and multiple roles during breast tumor progression. Inhibition of Notch receptors and ligands provides innovative therapeutic results and could become the therapy of choice in the next few years, even though further research is needed to reach safe conclusions.

Breast cancer development and progression: Risk factors, cancer stem cells, signaling pathways, genomics, and molecular pathogenesis

As the most commonly occurring cancer in women worldwide, breast cancer poses a formidable public health challenge on a global scale. Breast cancer consists of a group of biologically and molecularly heterogeneous diseases originated from the breast. While the risk factors associated with this cancer varies with respect to other cancers, genetic predisposition, most notably mutations in BRCA1 or BRCA2 gene, is an important causative factor for this malignancy. Breast cancers can begin in different areas of the breast, such as the ducts, the lobules, or the tissue in between. Within the large group of diverse breast carcinomas, there are various denoted types of breast cancer based on their invasiveness relative to the primary tumor sites. It is important to distinguish between the various subtypes because they have different prognoses and treatment implications. As there are remarkable parallels between normal development and breast cancer progression at the molecular level, it has been postulated that breast cancer may be derived from mammary cancer stem cells. Normal breast development and mammary stem cells are regulated by several signaling pathways, such as estrogen receptors (ERs), HER2, and Wnt/β-catenin signaling pathways, which control stem cell proliferation, cell death, cell differentiation, and cell motility. Furthermore, emerging evidence indicates that epigenetic regulations and noncoding RNAs may play important roles in breast cancer development and may contribute to the heterogeneity and metastatic aspects of breast cancer, especially for triple-negative breast cancer. This review provides a comprehensive survey of the molecular, cellular and genetic aspects of breast cancer.

Bioinformatics functional analysis of let-7a, miR-34a, and miR-199a/b reveals novel insights into immune system pathways and cancer hallmarks for hepatocellular carcinoma

Let-7a, miR-34a, and miR-199 a/b have gained a great attention as master regulators for cellular processes. In particular, these three micro-RNAs act as potential onco-suppressors for hepatocellular carcinoma. Bioinformatics can reveal the functionality of these micro-RNAs through target prediction and functional annotation analysis. In the current study, in silico analysis using innovative servers (miRror Suite, DAVID, miRGator V3.0, GeneTrail) has demonstrated the combinatorial and the individual target genes of these micro-RNAs and further explored their roles in hepatocellular carcinoma progression. There were 87 common target messenger RNAs (p ≤ 0.05) that were predicted to be regulated by the three micro-RNAs using miRror 2.0 target prediction tool. In addition, the functional enrichment analysis of these targets that was performed by DAVID functional annotation and REACTOME tools revealed two major immune-related pathways, eight hepatocellular carcinoma hallmarks-linked pathways, and two pathways that mediate interconnected processes between immune system and hepatocellular carcinoma hallmarks. Moreover, protein-protein interaction network for the predicted common targets was obtained by using STRING database. The individual analysis of target genes and pathways for the three micro-RNAs of interest using miRGator V3.0 and GeneTrail servers revealed some novel predicted target oncogenes such as SOX4, which we validated experimentally, in addition to some regulated pathways of immune system and hepatocarcinogenesis such as insulin signaling pathway and adipocytokine signaling pathway. In general, our results demonstrate that let-7a, miR-34a, and miR-199 a/b have novel interactions in different immune system pathways and major hepatocellular carcinoma hallmarks. Thus, our findings shed more light on the roles of these miRNAs as cancer silencers.

Dishevelled: A masterful conductor of complex Wnt signals

The Dishevelled gene was first identified in Drosophila mutants with disoriented hair and bristle polarity [1-3]. The Dsh gene (Dsh/Dvl, in Drosophila and vertebrates respectively) gained popularity when it was discovered that it plays a key role in segment polarity during early embryonic development in Drosophila [4]. Subsequently, the vertebrate homolog of Dishevelled genes were identified in Xenopus (Xdsh), mice (Dvl1, Dvl2, Dvl3), and in humans (DVL1, DVL2, DVL3) [5-10]. Dishevelled functions as a principal component of Wnt signaling pathway and governs several cellular processes including cell proliferation, survival, migration, differentiation, polarity and stem cell renewal. This review will revisit seminal discoveries and also summarize recent advances in characterizing the role of Dishevelled in both normal and pathophysiological settings.