Nodal signalling in embryogenesis and tumourigenesis

LADON, a Natural Antisense Transcript of NODAL, Promotes Tumour Progression and Metastasis in Melanoma

The TGFβ family member NODAL, repeatedly required during embryonic development, has also been associated with tumour progression. Our aim was to clarify the controversy surrounding its involvement in melanoma tumour progression. We found that the deletion of the NODAL exon 2 in a metastatic melanoma cell line impairs its ability to form tumours and colonize distant tissues. However, we show that this phenotype does not result from the absence of NODAL, but from a defect in the expression of a natural antisense transcript of NODAL, here called LADON. We show that LADON expression is specifically activated in metastatic melanoma cell lines, that its transcript is packaged in exosomes secreted by melanoma cells, and that, via its differential impact on the expression of oncogenes and tumour suppressors, it promotes the mesenchymal to amoeboid transition that is critical for melanoma cell invasiveness. LADON is, therefore, a new player in the regulatory network governing tumour progression in melanoma and possibly in other types of cancer.

Recruitment of TRIM33 to cell-context specific PML nuclear bodies regulates nodal signaling in mESCs

TRIM33 is a chromatin reader required for mammalian mesendoderm differentiation after activation of Nodal signaling, while its role in mESCs is still elusive. Here, we report that TRIM33 co-localizes with promyelocytic leukemia nuclear bodies (PML-NBs) specifically in mESCs, to mediate Nodal signaling-directed transcription of Lefty1/2. We show that TRIM33 puncta formation in mESCs depends on PML and on specific assembly of PML-NBs. Moreover, TRIM33 and PML co-regulate Lefty1/2 expression in mESCs, with both PML protein and formation of mESCs-specific PML-NBs being required for TRIM33 recruitment to these loci, and PML-NBs directly associating with the Lefty1/2 loci. Finally, a TurboID proximity-labeling experiment confirmed that TRIM33 is highly enriched only in mESCs-specific PML-NBs. Thus, our study supports a model in which TRIM33 condensates regulate Nodal signaling-directed transcription in mESCs and shows that PML-NBs can recruit distinct sets of client proteins in a cell-context-dependent manner.

Drug Repurposing at the Interface of Melanoma Immunotherapy and Autoimmune Disease

Cancer cells have a remarkable ability to evade recognition and destruction by the immune system. At the same time, cancer has been associated with chronic inflammation, while certain autoimmune diseases predispose to the development of neoplasia. Although cancer immunotherapy has revolutionized antitumor treatment, immune-related toxicities and adverse events detract from the clinical utility of even the most advanced drugs, especially in patients with both, metastatic cancer and pre-existing autoimmune diseases. Here, the combination of multi-omics, data-driven computational approaches with the application of network concepts enables in-depth analyses of the dynamic links between cancer, autoimmune diseases, and drugs. In this review, we focus on molecular and epigenetic metastasis-related processes within cancer cells and the immune microenvironment. With melanoma as a model, we uncover vulnerabilities for drug development to control cancer progression and immune responses. Thereby, drug repurposing allows taking advantage of existing safety profiles and established pharmacokinetic properties of approved agents. These procedures promise faster access and optimal management for cancer treatment. Together, these approaches provide new disease-based and data-driven opportunities for the prediction and application of targeted and clinically used drugs at the interface of immune-mediated diseases and cancer towards next-generation immunotherapies.

Association between cancer genes and germ layer specificity

Cancer signaling pathways defining cell fates are related to differentiation. During the developmental process, three germ layers (endoderm, mesoderm, and ectoderm) are formed during embryonic development that differentiate into organs via the epigenetic regulation of specific genes. To examine the relationship, the specificities of cancer gene mutations that depend on the germ layers are studied. The major organs affected by cancer were determined based on statistics from the National Cancer Information Center of Korea, and were grouped according to their germ layer origins. Then, the gene mutation frequencies were evaluated to identify any bias based on the differentiation group using the Catalogue of Somatic Mutations in Cancer (COSMIC) database. The chi-square test showed that the p-value of 152 of 166 genes was less than 0.05, and 151 genes showed p-values of less than 0.05 even after adjusting for the false discovery rate (FDR). The germ layer-specific genes were evaluated using visualization based on basic statistics, and the results matched the top ranking genes depending on organs in the COSMIC database.The current study confirmed the germ layer specificity of major cancer genes. The germ layer specificity of mutated driver genes is possibly important in cancer treatments because each mutated gene may react differently depending on the germ layer of origin. By understanding the mechanism of gene mutation in the development and progression of cancer in the context of cell-fate pathways, a more effective therapeutic strategy for cancer can be established.

Recurrent NOMO1 Gene Deletion Is a Potential Clinical Marker in Early-Onset Colorectal Cancer and Is Involved in the Regulation of Cell Migration

The incidence of early-onset colorectal cancer (EOCRC; age younger than 50 years) has been progressively increasing over the last decades globally, with causes unexplained. A distinct molecular feature of EOCRC is that compared with cases of late-onset colorectal cancer, in EOCRC cases, there is a higher incidence of Nodal Modulator 1 (NOMO1) somatic deletions. However, the mechanisms of NOMO1 in early-onset colorectal carcinogenesis are currently unknown. In this study, we show that in 30% of EOCRCs with heterozygous deletion of NOMO1, there were pathogenic mutations in this gene, suggesting that NOMO1 can be inactivated by deletion or mutation in EOCRC. To study the role of NOMO1 in EOCRC, CRISPR/cas9 technology was employed to generate NOMO1 knockout HCT-116 (EOCRC) and HS-5 (bone marrow) cell lines. NOMO1 loss in these cell lines did not perturb Nodal pathway signaling nor cell proliferation. Expression microarrays, RNA sequencing, and protein expression analysis by LC-IMS/MS showed that NOMO1 inactivation deregulates other signaling pathways independent of the Nodal pathway, such as epithelial-mesenchymal transition and cell migration. Significantly, NOMO1 loss increased the migration capacity of CRC cells. Additionally, a gut-specific conditional NOMO1 KO mouse model revealed no subsequent tumor development in mice. Overall, these findings suggest that NOMO1 could play a secondary role in early-onset colorectal carcinogenesis because its loss increases the migration capacity of CRC cells. Therefore, further study is warranted to explore other signalling pathways deregulated by NOMO1 loss that may play a significant role in the pathogenesis of the disease.

Effects of Pregnancy-Specific Glycoproteins on Trophoblast Motility in Three-Dimensional Gelatin Hydrogels

Introduction

Trophoblast invasion is a complex biological process necessary for establishment of pregnancy; however, much remains unknown regarding what signaling factors coordinate the extent of invasion. Pregnancy-specific glycoproteins (PSGs) are some of the most abundant circulating trophoblastic proteins in maternal blood during human pregnancy, with maternal serum concentrations rising to as high as 200-400 μg/mL at term.

Methods

Here, we employ three-dimensional (3D) trophoblast motility assays consisting of trophoblast spheroids encapsulated in 3D gelatin hydrogels to quantify trophoblast outgrowth area, viability, and cytotoxicity in the presence of PSG1 and PSG9 as well as epidermal growth factor and Nodal.

Results

We show PSG9 reduces trophoblast motility whereas PSG1 increases motility. Further, we assess bulk nascent protein production by encapsulated spheroids to highlight the potential of this approach to assess trophoblast response (motility, remodeling) to soluble factors and extracellular matrix cues.

Conclusions

Such models provide an important platform to develop a deeper understanding of early pregnancy.

Combinatorial Strategies to Target Molecular and Signaling Pathways to Disarm Cancer Stem Cells

Cancer is an urgent public health issue with a very huge number of cases all over the world expected to increase by 2040. Despite improved diagnosis and therapeutic protocols, it remains the main leading cause of death in the world. Cancer stem cells (CSCs) constitute a tumor subpopulation defined by ability to self-renewal and to generate the heterogeneous and differentiated cell lineages that form the tumor bulk. These cells represent a major concern in cancer treatment due to resistance to conventional protocols of radiotherapy, chemotherapy and molecular targeted therapy. In fact, although partial or complete tumor regression can be achieved in patients, these responses are often followed by cancer relapse due to the expansion of CSCs population. The aberrant activation of developmental and oncogenic signaling pathways plays a relevant role in promoting CSCs therapy resistance. Although several targeted approaches relying on monotherapy have been developed to affect these pathways, they have shown limited efficacy. Therefore, an urgent need to design alternative combinatorial strategies to replace conventional regimens exists. This review summarizes the preclinical studies which provide a proof of concept of therapeutic efficacy of combinatorial approaches targeting the CSCs.

Genetically-encoded discovery of proteolytically stable bicyclic inhibitors for morphogen NODAL

In this manuscript, we developed a two-fold symmetric linchpin (TSL) that converts readily available phage-displayed peptides libraries made of 20 common amino acids to genetically-encoded libraries of bicyclic peptides displayed on phage. TSL combines an aldehyde-reactive group and two thiol-reactive groups; it bridges two side chains of cysteine [C] with an N-terminal aldehyde group derived from the N-terminal serine [S], yielding a novel bicyclic topology that lacks a free N-terminus. Phage display libraries of SX1CX2X3X4X5X6X7C sequences, where X is any amino acid but Cys, were converted to a library of bicyclic TSL-[S]X1[C]X2X3X4X5X6X7[C] peptides in 45 ± 15% yield. Using this library and protein morphogen NODAL as a target, we discovered bicyclic macrocycles that specifically antagonize NODAL-induced signaling in cancer cells. At a 10 μM concentration, two discovered bicyclic peptides completely suppressed NODAL-induced phosphorylation of SMAD2 in P19 embryonic carcinoma cells. The TSL-[S]Y[C]KRAHKN[C] bicycle inhibited NODAL-induced proliferation of NODAL-TYK-nu ovarian carcinoma cells with apparent IC50 of 1 μM. The same bicycle at 10 μM concentration did not affect the growth of the control TYK-nu cells. TSL-bicycles remained stable over the course of the 72 hour-long assays in a serum-rich cell-culture medium. We further observed general stability in mouse serum and in a mixture of proteases (Pronase™) for 21 diverse bicyclic macrocycles of different ring sizes, amino acid sequences, and cross-linker geometries. TSL-constrained peptides to expand the previously reported repertoire of phage-displayed bicyclic architectures formed by cross-linking Cys side chains. We anticipate that it will aid the discovery of proteolytically stable bicyclic inhibitors for a variety of protein targets.

The effect of Activin pathway modulation on the expression of both pluripotency and differentiation markers during early zebrafish development compared with other vertebrates

Activin-like factors control many developmental processes, including pluripotency maintenance and differentiation. Although Activin-like factors' action in mesendoderm induction has been demonstrated in zebrafish, their involvement in preserving the stemness remains unknown. To investigate the role of maternal Activin-like factors, their effects were promoted or blocked using synthetic human Activin A or SB-431542 treatments respectively until the maternal to zygotic transition. To study the role of zygotic Activin-like factors, SB-431542 treatment was also applied after the maternal to zygotic transition. The effect of the pharmacological modulations of the Activin/Smad pathway was then studied on the mRNA expressions of the ndr1, ndr2, tbxta (no tail/ntl) as the differentiation index, mych, nanog, and oct4 (pou5f3) as the pluripotency markers of the zebrafish embryonic cells as well as sox17 as a definitive endoderm marker. Expression of the target genes was measured at the 16-cell, 256-cell, 1K-cell, oblong, dome, and shield stages using the real-time quantitative polymerase chain reaction (RT-qPCR). Activation of the maternal Activin signaling pathway led to an increase in zygotic expression of the tbxta, particularly marked at the oblong stage. In other words, promotion of the maternal Activin/Smad pathway induced differentiation by advancing the major peaks of ndr1 and nanog, thereby eliciting tbxta expression. Whereas suppression of the maternal or zygotic Activin/Smad pathway sustained the pluripotency by preventing the major peaks of ndr1 and nanog as well as tbxta encoding.

Embryonic protein NODAL regulates the breast tumor microenvironment by reprogramming cancer-derived secretomes

The tumor microenvironment (TME) is an important mediator of breast cancer progression. Cancer-associated fibroblasts constitute a major component of the TME and may originate from tissue-associated fibroblasts or infiltrating mesenchymal stromal cells (MSCs). The mechanisms by which cancer cells activate fibroblasts and recruit MSCs to the TME are largely unknown, but likely include deposition of a pro-tumorigenic secretome. The secreted embryonic protein NODAL is clinically associated with breast cancer stage and promotes tumor growth, metastasis, and vascularization. Herein, we show that NODAL expression correlates with the presence of activated fibroblasts in human triple-negative breast cancers and that it directly induces Cancer-associated fibroblasts phenotypes. We further show that NODAL reprograms cancer cell secretomes by simultaneously altering levels of chemokines (e.g., CXCL1), cytokines (e.g., IL-6) and growth factors (e.g., PDGFRA), leading to alterations in MSC chemotaxis. We therefore demonstrate a hitherto unappreciated mechanism underlying the dynamic regulation of the TME.

ECM deposition is driven by caveolin-1-dependent regulation of exosomal biogenesis and cargo sorting

The composition and physical properties of the extracellular matrix (ECM) critically influence tumor progression, but the molecular mechanisms underlying ECM layering are poorly understood. Tumor–stroma interaction critically depends on cell communication mediated by exosomes, small vesicles generated within multivesicular bodies (MVBs). We show that caveolin-1 (Cav1) centrally regulates exosome biogenesis and exosomal protein cargo sorting through the control of cholesterol content at the endosomal compartment/MVBs. Quantitative proteomics profiling revealed that Cav1 is required for exosomal sorting of ECM protein cargo subsets, including Tenascin-C (TnC), and for fibroblast-derived exosomes to efficiently deposit ECM and promote tumor invasion. Cav1-driven exosomal ECM deposition not only promotes local stromal remodeling but also the generation of distant ECM-enriched stromal niches in vivo. Cav1 acts as a cholesterol rheostat in MVBs, determining sorting of ECM components into specific exosome pools and thus ECM deposition. This supports a model by which Cav1 is a central regulatory hub for tumor–stroma interactions through a novel exosome-dependent ECM deposition mechanism.

Nodal is involved in chemoresistance of renal cell carcinoma cells via regulation of ABCB1

Renal cell carcinoma (RCC) is the third most frequent malignancy within urological oncology. Understanding mechanisms of chemoresistance in RCC cell is important for therapy and drug development. We established cisplatin (CDDP) resistant RCC cells by treating cells with increasing concentrations of CDDP. Nodal, an important embryonic morphogen, was increased in RCC/CDDP cells. Targeted inhibition of Nodal via its siRNA or neutralization antibody restored sensitivity of RCC resistant cells to CDDP treatment. It was due to that si-Nodal can decrease expression of P-glycoprotein (P-gp, encoded by ABCB1), one important ATP-binding cassette (ABC) membrane transporter for drug efflux. si-Nodal can decrease the transcription and promoter activity of ABCB1. Mechanistically, si-Nodal can decrease the phosphorylation of p65, which can bind to the promoter of ABCB1 and then trigger its transcription. Further, CDDP treatment decreased the expression of Nodal in culture medium of RCC cells. Collectively, we found that Nodal can regulate chemoresistance of RCC cells via regulating transcription of ABCB1.

Differential genetic mutations of ectoderm, mesoderm, and endoderm-derived tumors in TCGA database

Background

In terms of biological behavior, gene regulation, or signaling pathways, there is a certain similarity between tumorigenesis and embryonic development of humans. Three germ layer structure exhibits the distinct ability to form specific tissues and organs.

Methods

The present study set out to investigate the genetic mutation characteristics of germ layer differentiation-related genes using the tumor cases of the cancer genome atlas (TCGA) database.

Results

These tumor samples were divided into three groups, including the ectoderm, mesoderm, and endoderm. Children cases less than 9 years old accounted for a larger proportion for the cases in the ectoderm and mesoderm groups; whereas the middle-aged and elderly individuals (from 50 to 89 years old) were more susceptible to tumors of endoderm. There was a better prognosis for the cases of mesoderm, especially the male with the race of White, compared with the other groups. A missense mutation was frequently detected for the cases of ectoderm and endoderm, while deletion mutation was common for that of mesoderm. We could not identify the ectoderm, mesoderm, or endoderm-specific mutated genes or variants with high mutation frequency. However, there was a relatively higher mutation incidence of endoderm markers (GATA6, FOXA2, GATA4, AFP) in the endoderm group, compared with the groups of ectoderm and mesoderm. Additionally, four members (SMO, GLI1, GLI2, GLI3) within the Hedgehog signaling pathway genes showed a relatively higher mutation rate in the endoderm group than the other two groups.

Conclusions

TCGA tumors of ectoderm, mesoderm, and endoderm groups exhibit the distinct subject distribution, survival status, and genomic alteration characteristics. The synergistic mutation effect of specific genes closely related to embryonic development may contribute to the tumorigenesis of tissues or organs derived from the specific germ layers. This study provides a novel reference for exploring the functional connection between embryogenesis and tumorigenesis.

Transient Nodal Signaling in Left Precursors Coordinates Opposed Asymmetries Shaping the Heart Loop

The secreted factor Nodal, known as a major left determinant, is associated with severe heart defects. Yet, it has been unclear how it regulates asymmetric morphogenesis such as heart looping, which align cardiac chambers to establish the double blood circulation. Here, we report that Nodal is transiently active in precursors of the mouse heart tube poles, before looping. In conditional mutants, we show that Nodal is not required to initiate asymmetric morphogenesis. We provide evidence of a heart-specific random generator of asymmetry that is independent of Nodal. Using 3D quantifications and simulations, we demonstrate that Nodal functions as a bias of this mechanism: it is required to amplify and coordinate opposed left-right asymmetries at the heart tube poles, thus generating a robust helical shape. We identify downstream effectors of Nodal signaling, regulating asymmetries in cell proliferation, differentiation, and extracellular matrix composition. Our study uncovers how Nodal regulates asymmetric organogenesis.

Aberrantly Expressed Embryonic Protein NODAL Alters Breast Cancer Cell Susceptibility to γδ T Cell Cytotoxicity

Gamma delta (γδ) T cells kill transformed cells, and increased circulating γδ T cells levels correlate with improved outcome in cancer patients; however, their function within the breast tumor microenvironment (TME) remains controversial. As tumors progress, they begin to express stem-cell associated proteins, concomitant with the emergence of therapy resistant metastatic disease. For example, invasive breast cancers often secrete the embryonic morphogen, NODAL. NODAL has been shown to promote angiogenesis, therapy resistance and metastasis in breast cancers. However, to date, little is known about how this secreted protein may interact with cells in the TME. Herein we explore how NODAL in the TME may influence γδ T cell function. We have assessed the proximity of γδ T cells to NODAL in a cohort of triple negative breast tumors. In all cases in which γδ T cells could be identified in these tumors, γδ T cells were found in close proximity to NODAL-expressing tumor cells. Migration of γδ and αβ T cells was similar toward MDA-MB-231 cells in which NODAL had been knocked down (shN) and MDA-MB-231 scrambled control cells (shC). Furthermore, Vδ1 γδ T cells did not migrate preferentially toward conditioned medium from these cell lines. While 24-h exposure to NODAL did not impact CD69, PD-1, or T cell antigen receptor (TCR) expression on γδ T cells, long term exposure resulted in decreased Vδ2 TCR expression. Maturation of γδ T cells was not significantly influenced by NODAL stimulation. While neither short- nor long-term NODAL stimulation impacted the ability of γδ T cells to kill MCF-7 breast cancer cells, the absence of NODAL resulted in greater sensitivity of targets to γδ T cell cytotoxicity, while overexpression of NODAL conferred resistance. This appeared to be at least in part due to an inverse correlation between NODAL and surface MICA/B expression on breast cancer target lines. As such, it appears that NODAL may play a role in strategies employed by breast cancer cells to evade γδ T cell targeting, and this should be considered in the development of safe and effective γδ T cell immunotherapies.

Translational control of breast cancer plasticity

Plasticity of neoplasia, whereby cancer cells attain stem-cell-like properties, is required for disease progression and represents a major therapeutic challenge. We report that in breast cancer cells NANOG, SNAIL and NODAL transcripts manifest multiple isoforms characterized by different 5' Untranslated Regions (5'UTRs), whereby translation of a subset of these isoforms is stimulated under hypoxia. The accumulation of the corresponding proteins induces plasticity and "fate-switching" toward stem cell-like phenotypes. Mechanistically, we observe that mTOR inhibitors and chemotherapeutics induce translational activation of a subset of NANOG, SNAIL and NODAL mRNA isoforms akin to hypoxia, engendering stem-cell-like phenotypes. These effects are overcome with drugs that antagonize translational reprogramming caused by eIF2α phosphorylation (e.g. ISRIB), suggesting that the Integrated Stress Response drives breast cancer plasticity. Collectively, our findings reveal a mechanism of induction of plasticity of breast cancer cells and provide a molecular basis for therapeutic strategies aimed at overcoming drug resistance and abrogating metastasis.

Establishment of a Gorlin syndrome model from induced neural progenitor cells exhibiting constitutive GLI1 expression and high sensitivity to inhibition by smoothened (SMO)

The hedgehog signaling pathway is a vital factor for embryonic development and stem cell maintenance. Dysregulation of its function results in tumor initiation and progression. The aim of this research was to establish a disease model of hedgehog-related tumorigenesis with Gorlin syndrome-derived induced pluripotent stem cells (GS-iPSCs). Induced neural progenitor cells from GS-iPSCs (GS-NPCs) show constitutive high GLI1 expression and higher sensitivity to smoothened (SMO) inhibition compared with wild-type induced neural progenitor cells (WT-NPCs). The differentiation process from iPSCs to NPCs may have similarity in gene expression to Hedgehog signal-related carcinogenesis. Therefore, GS-NPCs may be useful for screening compounds to find effective drugs to control Hedgehog signaling activity.

Long Non-Coding RNA NANCI/NKX2-1 Duplex Impacts Prognosis in Stage I Non-Small-Cell Lung Cancer

BACKGROUND

NANCI, an intergenic long non-coding RNA (lncRNA) is essential for buffering NKX2-1 expression during embryonic development and in adult tissue. We analyzed NANCI and NKX2-1 in human lung embryonic samples and adult lung tissues and evaluated their potential as prognostic markers in stage I non-small cell lung cancer (NSCLC).

METHODS AND RESULTS

NANCI and NKX2-1 expression was assessed by TaqMan assays in 18 human embryonic samples from 8 to 13 weeks, 59 non-tumoral (NT) lung tissue samples, and 98 stage I NSCLC tumor samples. NANCI and NKX2-1 expression in embryonic and NSCLC samples were downregulated in comparison to adult NT tissue. Patients with low expression of NANCI had shorter disease-free survival (DFS) and overall survival (OS) than those with high levels (47.6 vs 69.3 months, P=0.032 and 57.7 vs 77.6 months, P=0.021, respectively). When the expression levels of NANCI and NKX2-1 were evaluated in combination, four groups were identified (high NANCI/high NKX2-1, low NANCI/high NKX2-1, high NANCI/low NKX2-1 and low NANCI/low NKX2-1) with differential impact on DFS (P=0.042) and OS (P=0.024). Interestingly, the high NANCI/high NKX2-1 duplex group had longer DFS and OS than the other three groups (71.25 vs 46.3 months, P=0.009 and 81.3 vs 56.1 months, P=0.004, respectively). In the multivariate analysis, the high NANCI/high NKX2-1 duplex was identified as an independent prognostic factor for longer DFS (HR 0.346, 95% CI, 0.169-0.709; P=0.004) and OS (HR 0.309, 95% CI, 0.121-0.786; P=0.014).

CONCLUSIONS

NANCI and the NANCI-NKX2-1 duplex impacts prognosis in stage I NSCLC patients.

Nodal promotes the malignancy of non-small cell lung cancer (NSCLC) cells via activation of NF-κB/IL-6 signals

Non-small cell lung cancer (NSCLC) is one of the leading causes of cancer deaths worldwide. Understanding the mechanisms responsible for the malignancy of NSCLC cells is important for therapy and drug development. Nodal, an important embryonic morphogen, has been reported to modulate tumorigenesis. We found that Nodal can trigger the proliferation of NSCLC cells and decrease the sensitivity to doxorubicin (Dox) and cisplatin (CDDP) treatment. Targeted inhibition of Nodal can suppress the proliferation of NSCLC cells. Among the measured cytokines, Nodal can increase the expression of interleukin-6 (IL-6) and vascular endothelial growth factor A (VEGFA) in NSCLC cells. Inhibition of IL-6, while not VEGFA, attenuated Nodal induced cell proliferation, suggesting the essential roles of IL-6 in Nodal induced malignancy of NSCLC cells. Nodal can trigger the phosphorylation, nuclear translocation and transcriptional activities of p65, the key signal transducer of NF-κB. This was due to the fact that Nodal can increase the phosphorylation of IKKβ/IκBα. The inhibitor of IKKβ abolished Nodal induced activation of p65 and expression of IL-6. Collectively, we found that Nodal can increase the proliferation and decrease chemosensitivity of NSCLC cells via regulation of NF-κB/IL-6 signals. It indicated that Nodal might be a potential therapeutic target for NSCLC treatment.

Expression of Lefty predicts Merkel cell carcinoma-specific death

BACKGROUND

Lefty and Nodal are transforming growth factor β-related proteins, which, beside their role in determination of laterality during embryogenesis, have also been linked with cancer progression.

OBJECTIVES

Prompted by the observed significant left-sided laterality of Merkel cell carcinoma (MCC), we addressed whether Lefty and Nodal are expressed in MCC and correlated expression patterns with clinical parameters such as MCC laterality and patient outcome.

METHODS

Expression of Lefty and Nodal in primary MCC was assessed in 29 patients by immunohistochemistry. The histology (H-)score was calculated and correlated with clinical parameters.

RESULTS

The median (range) H-score of Lefty and Nodal was 17.6 (0-291) and 74.9 (0.7-272), respectively. There was a significant correlation between Lefty expression and Nodal expression (correlation coefficient of 0.60, P = 0.0006). There was no significant correlation between Lefty expression and Nodal expression with either tumour laterality, gender, age, Merkel cell polyomavirus status, disease stage, anatomical localization of primary tumours or disease relapse. On univariate analysis, low Lefty expression and Nodal expression were significantly associated with MCC-specific death (P = 0.010 and P = 0.019, respectively). On univariate analysis, low Lefty expression was the only significant independent predictor for MCC-specific death (P = 0.025) as indicated by an odds ratio of 14 (95% CI: 1.43-137.33).

CONCLUSIONS

Lefty and Nodal are frequently expressed in MCC, but not correlated with tumour laterality. Importantly, our data suggest that a low level of Lefty expression in primary MCC is a strong predictor of MCC-specific death.

Promotion effects of mono-2-ethyhexyl phthalate (MEHP) on migration and invasion of human melanoma cells via activation of TGF-β signals

Malignant melanoma is one of the most leading forms of skin cancer associated with a low patient survival rate. There is an urgent need to illustrate risk factors that can trigger the motility of melanoma cancer cells. Our present study revealed that mono-(2-ethylhexyl)phthalate (MEHP) exposure can significantly increase the in vitro migration and invasion of WM983A and A375 cells. Among the tested cytokines, MEHP can increase the expression of transforming growth factor β (TGF-β). Inhibition of TGF-β via its neutralization antibody can attenuate MEHP-induced cell migration and invasion. Further, upregulation of TGF-β mediated MEHP-induced activation of Smad signals and upregulation of Snail in melanoma cells. Blocking the TGF-β/Smad signal pathway can attenuate MEHP-induced cell migration. Estrogen receptor α (ERα) was essential for MEHP-induced expression of TGF-β. In addition, MEHP can increase the expression of ERα in melanoma cells. Collectively, our study found that MEHP can stimulate the progression of melanoma via TGF-β signals. SIGNIFICANCE: Mono-(2-ethylhexyl)phthalate (MEHP) is the active and most toxic metabolite of di(2-ethylhexyl)phthalate (DEHP). Our present study revealed that MEHP can trigger the in vitro migration and invasion of melanoma cells via upregulation of TGF-β/Snail signals. It revealed that daily exposure to MEHP might be a risk factor for melanoma patients.

Role of cell-to-cell communication in cancer: New features, insights, and directions

The current special issue entitled "Role of tunneling nanotubes (TNTs) in carcinogenesis" was designed to discuss the role of cell-to-cell communication, especially TNTs, in cancer pathogenesis. In addition, we discuss the exploitation of TNTs as a potential therapeutic target to prevent and reduce cancer incidence. It is accepted that cell-to-cell communication is essential for the development of multicellular systems, and it is coordinated by soluble factors, associated membrane proteins, exosomes, gap junction channels, and TNTs. An old belief in the cancer field is that cancer cells are "disconnected" from healthy cells, resulting in loss of cell-to-cell communication and neighbor control. However, recent data obtained from different kind of tumors indicate that TNTs and others forms of communication (exosomes and localized cell-to-cell communication) are highly expressed and functional during tumor development . In physiological conditions, TNTs are expressed by few cells, and their main function is to coordinate long-distance signaling. However, upon carcinogenesis, TNTs proliferate and provide an alternative route of communication to enable the transfer of several signaling molecules and organelles to spread disease and toxicity. We propose that TNTs and their cargo are an attractive therapeutic target to reduce or prevent cancer development. All these unique aspects of cell-to-cell diffusion and organelle sharing will be discussed in this special issue.

Targeting Nodal and Cripto-1: Perspectives Inside Dual Potential Theranostic Cancer Biomarkers

BACKGROUND

Elucidating the mechanisms of recurrence of embryonic signaling pathways in tumorigenesis has led to the discovery of onco-fetal players which have physiological roles during normal development but result aberrantly re-activated in tumors. In this context, Nodal and Cripto-1 are recognized as onco-developmental factors, which are absent in normal tissues but are overexpressed in several solid tumors where they can serve as theranostic agents.

OBJECTIVE

To collect, review and discuss the most relevant papers related to the involvement of Nodal and Cripto-1 in the development, progression, recurrence and metastasis of several tumors where they are over-expressed, with a particular attention to their occurrence on the surface of the corresponding sub-populations of cancer stem cells (CSC).

RESULTS

We have gathered, rationalized and discussed the most interesting findings extracted from some 370 papers related to the involvement of Cripto-1 and Nodal in all tumor types where they have been detected. Data demonstrate the clear connection between Nodal and Cripto-1 presence and their multiple oncogenic activities across different tumors. We have also reviewed and highlighted the potential of targeting Nodal, Cripto-1 and the complexes that they form on the surface of tumor cells, especially of CSC, as an innovative approach to detect and suppress tumors with molecules that block one or more mechanisms that they regulate.

CONCLUSION

Overall, Nodal and Cripto-1 represent two innovative and effective biomarkers for developing potential theranostic anti-tumor agents that target normal as well as CSC subpopulations and overcome both pharmacological resistance and tumor relapse.

Nodal pathway activation due to Akt1 suppression is a molecular switch for prostate cancer cell epithelial-to-mesenchymal transition and metastasis

Several studies have unraveled the negative role of Akt1 in advanced cancers, including metastatic prostate cancer (mPCa). Hence, understanding the consequences of targeting Akt1 in the mPCa and identifying its downstream novel targets is essential. We studied how Akt1 deletion in PC3 and DU145 cells activates the Nodal pathway and promotes PCa epithelial-to-mesenchymal transition (EMT) and metastasis. Here we show that Akt1 loss increases Nodal expression in PCa cells accompanied by activation of FoxO1/3a, and EMT markers Snail and N-cadherin as well as loss of epithelial marker E-cadherin. Treatment with FoxO inhibitor AS1842856 abrogated the Nodal expression in Akt1 deleted PCa cells. Akt1 deficient PCa cells exhibited enhanced cell migration and invasion in vitro and lung metastasis in vivo, which were attenuated by treatment with Nodal pathway inhibitor SB505124. Interestingly, Nodal mRNA analysis from two genomic studies in cBioportal showed a positive correlation between Nodal expression and Gleason score indicating the positive role of Nodal in human mPCa. Collectively, our data demonstrate Akt1-FoxO3a-Nodal pathway as an important mediator of PCa metastasis and present Nodal as a potential target to treat mPCa patients.

Nodal increases the malignancy of childhood neuroblastoma cells via regulation of Zeb1

Neuroblastoma (NB) is one of the most common malignant tumors derived from pluripotent cells of the neural crest. Nodal is an important embryonic morphogen which can re-express in cancer cells. The roles of Nodal in the progression of NB are not illustrated. Our present study reveals that Nodal is upregulated in NB cells and tissues. Targeted inhibition of Nodal can suppress the in vitro migration and invasion of NB cells while increase its chemo-sensitivity to doxorubicin (Dox) treatment. Nodal positively regulates the expression of Zeb1, one well-known transcription factors of epithelial to mesenchymal transition (EMT) of cancer cells. Knockdown of Zeb1 can attenuate Nodal-induced malignancy of NB cells. Mechanistically, Nodal increases the protein stability of Zeb1 while has no effect on its mRNA expression. It is due to that Nodal can increase the expression of Ataxia telangiectasia mutated kinase (ATM), which can phosphorylate and stabilize Zeb1 in cancer cells. Collectively, our data revealed that Nodal can increase the malignancy of NB cells via increasing the expression of Zeb1. It suggests that targeted inhibition of Nodal might be a potential therapy approach for NB treatment. © 2019 BioFactors, 45(3):355-363, 2019.

Exploring major signaling cascades in melanomagenesis: a rationale route for targetted skin cancer therapy

Although most melanoma cases may be treated by surgical intervention upon early diagnosis, a significant portion of patients can still be refractory, presenting low survival rates within 5 years after the discovery of the illness. As a hallmark, melanomas are highly prone to evolve into metastatic sites. Moreover, melanoma tumors are highly resistant to most available drug therapies and their incidence have increased over the years, therefore leading to public health concerns about the development of novel therapies. Therefore, researches are getting deeper in unveiling the mechanisms by which melanoma initiation can be triggered and sustained. In this context, important progress has been achieved regarding the roles and the impact of cellular signaling pathways in melanoma. This knowledge has provided tools for the development of therapies based on the intervention of signal(s) promoted by these cascades. In this review, we summarize the importance of major signaling pathways (mitogen-activated protein kinase (MAPK), phosphoinositide 3-kinase (PI3K)-Akt, Wnt, nuclear factor κ-light-chain-enhancer of activated B cell (NF-κB), Janus kinase (JAK)-signal transducer and activator of transcription (STAT), transforming growth factor β (TGF-β) and Notch) in skin homeostasis and melanoma progression. Available and developing melanoma therapies interfering with these signaling cascades are further discussed.

Spatial and temporal control of NODAL signaling

Embryonic development is orchestrated by the activity of signal transduction pathways, amongst which are those downstream of the transforming growth factor β (TGF-β) family. Here I focus on signalling by one of these ligands, NODAL, which is essential for early embryonic axis patterning. I review recent advances in our understanding of how NODAL signalling is transduced from the plasma membrane to the nucleus to regulate the transcription of target genes, and how domains of NODAL activity are established and refined during embryonic development. The duration of signalling is emerging as a key determinant of the specificity of downstream responses in terms of cell fate decisions and I will discuss what is currently known about the underlying mechanisms.

Nodal signalling and asymmetry of the nervous system

The role of Nodal signalling in nervous system asymmetry is still poorly understood. Here, we review and discuss how asymmetric Nodal signalling controls the ontogeny of nervous system asymmetry using a comparative developmental perspective. A detailed analysis of asymmetry in ascidians and fishes reveals a critical context-dependency of Nodal function and emphasizes that bilaterally paired and midline-unpaired structures/organs behave as different entities. We propose a conceptual framework to dissect the developmental function of Nodal as asymmetry inducer and laterality modulator in the nervous system, which can be used to study other types of body and visceral organ asymmetries. Using insights from developmental biology, we also present novel evolutionary hypotheses on how Nodal led the evolution of directional asymmetry in the brain, with a particular focus on the epithalamus. We intend this paper to provide a synthesis on how Nodal signalling controls left-right asymmetry of the nervous system.This article is part of the themed issue 'Provocative questions in left-right asymmetry'.

Vg1-Nodal heterodimers are the endogenous inducers of mesendoderm

Nodal is considered the key inducer of mesendoderm in vertebrate embryos and embryonic stem cells. Other TGF-beta-related signals, such as Vg1/Dvr1/Gdf3, have also been implicated in this process but their roles have been unclear or controversial. Here we report that zebrafish embryos without maternally provided vg1 fail to form endoderm and head and trunk mesoderm, and closely resemble nodal loss-of-function mutants. Although Nodal is processed and secreted without Vg1, it requires Vg1 for its endogenous activity. Conversely, Vg1 is unprocessed and resides in the endoplasmic reticulum without Nodal, and is only secreted, processed and active in the presence of Nodal. Co-expression of Nodal and Vg1 results in heterodimer formation and mesendoderm induction. Thus, mesendoderm induction relies on the combination of two TGF-beta-related signals: maternal and ubiquitous Vg1, and zygotic and localized Nodal. Modeling reveals that the pool of maternal Vg1 enables rapid signaling at low concentrations of zygotic Nodal.

All animals begin life as just one cell – a fertilized egg. In order to make a recognizable adult, each embryo needs to make the three types of tissue that will eventually form all of the organs: endoderm, which will form the internal organs; mesoderm, which will form the muscle and bones; and ectoderm, which will generate the skin and nervous system.

All vertebrates – animals with backbones like fish and humans – use the so-called Nodal signaling pathway to make the endoderm and mesoderm. Nodal is a signaling molecule that binds to receptors on the surface of cells. If Nodal binds to a receptor on a cell, it instructs that cell to become endoderm or mesoderm. As such, Nodal is critical for vertebrate life. However, there has been a 30-year debate in the field of developmental biology about whether a protein called Vg1, which has a similar molecular structure as Nodal, plays a role in the early development of vertebrates.

Zebrafish are often used to study animal development, and Montague and Schier decided to test whether these fish need the gene for Vg1 (also known as Gdf3) by deleting it using a genome editing technique called CRISPR/Cas9. It turns out that female zebrafish can survive without this gene. Yet, when the offspring of these females do not inherit the instructions to make Vg1 from their mothers, they fail to form the endoderm and mesoderm. This means that the embryos do not have hearts, blood or other internal organs, and they die within three days. Two other groups of researchers have independently reported similar results.

The findings reveal that Vg1 is critical for the Nodal signaling pathway to work in zebrafish. Montague and Schier then showed that, in this pathway, Nodal does not activate its receptors on its own. Instead, Nodal must interact with Vg1, and it is this Nodal-Vg1 complex that activates receptors, and instructs cells to become endoderm and mesoderm.

Scientists currently use the Nodal signaling pathway to induce human embryonic stem cells growing in the laboratory to become mesoderm and endoderm. As such, these new findings could ultimately help researchers to grow tissues and organs for human patients.

Cancer as an ecomolecular disease and a neoplastic consortium

Current anticancer paradigms largely target driver mutations considered integral for cancer cell survival and tumor progression. Although initially successful, many of these strategies are unable to overcome the tremendous heterogeneity that characterizes advanced tumors, resulting in the emergence of resistant disease. Cancer is a rapidly evolving, multifactorial disease that accumulates numerous genetic and epigenetic alterations. This results in wide phenotypic and molecular heterogeneity within the tumor, the complexity of which is further amplified through specific interactions between cancer cells and the tumor microenvironment. In this context, cancer may be perceived as an "ecomolecular" disease that involves cooperation between several neoplastic clones and their interactions with immune cells, stromal fibroblasts, and other cell types present in the microenvironment. This collaboration is mediated by a variety of secreted factors. Cancer is therefore analogous to complex ecosystems such as microbial consortia. In the present article, we comment on the current paradigms and perspectives guiding the development of cancer diagnostics and therapeutics and the potential application of systems biology to untangle the complexity of neoplasia. In our opinion, conceptualization of neoplasia as an ecomolecular disease is warranted. Advances in knowledge pertinent to the complexity and dynamics of interactions within the cancer ecosystem are likely to improve understanding of tumor etiology, pathogenesis, and progression. This knowledge is anticipated to facilitate the design of new and more effective therapeutic approaches that target the tumor ecosystem in its entirety.

Targeting the Stem Cell Properties of Adult Breast Cancer Cells: Using Combinatorial Strategies to Overcome Drug Resistance

PURPOSE OF REVIEW

Cancer is a major public health problem worldwide. In aggressive cancers, which are heterogeneous in nature, there exists a paucity of targetable molecules that can be used to predict outcome and response to therapy in patients, especially those in the high risk category with a propensity to relapse following chemotherapy. This review addresses the challenges pertinent to treating aggressive cancer cells with inherent stem cell properties, with a special focus on triple-negative breast cancer (TNBC).

RECENT FINDINGS

Plasticity underlies the cancer stem cell (CSC) phenotype in aggressive cancers like TNBC. Progenitors and CSCs implement similar signaling pathways to sustain growth, and the convergence of embryonic and tumorigenic signaling pathways has led to the discovery of novel oncofetal targets, rigorously regulated during normal development, but aberrantly reactivated in aggressive forms of cancer.

SUMMARY

Translational studies have shown that Nodal, an embryonic morphogen, is reactivated in aggressive cancers, but not in normal tissues, and underlies tumor growth, invasion, metastasis and drug resistance. Front-line therapies do not inhibit Nodal, but when a combinatorial approach is used with an agent such as doxorubicin followed by anti-Nodal antibody therapy, significant decreases in cell growth and viability occur. These findings are of special interest in the development of new therapeutic interventions that target the stem cell properties of cancer cells to overcome drug resistance and metastasis.

Epithelial-to-Mesenchymal Transition in the Female Reproductive Tract: From Normal Functioning to Disease Pathology

Epithelial-to-mesenchymal transition (EMT) is a physiological process that is vital throughout the human lifespan. In addition to contributing to the development of various tissues within the growing embryo, EMT is also responsible for wound healing and tissue regeneration later in adulthood. In this review, we highlight the importance of EMT in the development and normal functioning of the female reproductive organs (the ovaries and the uterus) and describe how dysregulation of EMT can lead to pathological conditions, such as endometriosis, adenomyosis, and carcinogenesis. We also summarize the current literature relating to EMT in the context of ovarian and endometrial carcinomas, with a particular focus on how molecular mechanisms and the tumor microenvironment can govern cancer cell plasticity, therapy resistance, and metastasis.

Nodal expression in triple-negative breast cancer: Cellular effects of its inhibition following doxorubicin treatment

Triple-negative breast cancer (TNBC) represents an aggressive cancer subtype characterized by the lack of expression of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). The independence of TNBC from these growth promoting factors eliminates the efficacy of therapies which specifically target them, and limits TNBC patients to traditional systemic neo/adjuvant chemotherapy. To better understand the growth advantage of TNBC - in the absence of ER, PR and HER2, we focused on the embryonic morphogen Nodal (associated with the cancer stem cell phenotype), which is re-expressed in aggressive breast cancers. Most notably, our previous data demonstrated that inhibition of Nodal signaling in breast cancer cells reduces their tumorigenic capacity. Furthermore, inhibiting Nodal in other cancers has resulted in improved effects of chemotherapy, although the mechanisms for this remain unknown. Thus, we hypothesized that targeting Nodal in TNBC cells in combination with conventional chemotherapy may improve efficacy and represent a potential new strategy. Our preliminary data demonstrate that Nodal is highly expressed in TNBC when compared to invasive hormone receptor positive samples. Treatment of Nodal expressing TNBC cell lines with a neutralizing anti-Nodal antibody reduces the viability of cells that had previously survived treatment with the anthracycline doxorubicin. We show that inhibiting Nodal may alter response mechanisms employed by cancer cells undergoing DNA damage. These data suggest that development of therapies which target Nodal in TNBC may lead to additional treatment options in conjunction with chemotherapy regimens - by altering signaling pathways critical to cellular survival.

Targeting melanoma with front-line therapy does not abrogate Nodal-expressing tumor cells

Metastatic melanoma is a highly aggressive skin cancer with a poor prognosis. It is the leading cause of skin cancer deaths with a median overall survival for advanced-stage metastatic disease of <6 months. Despite advances in the field with conventional and targeted therapies, the heterogeneity of melanoma poses the greatest ongoing challenge, ultimately leading to relapse and progression to a more drug-resistant tumor in most patients. Particularly noteworthy are recent findings, indicating that these therapies exert selective pressure on tumors resulting in the activation of pathways associated with cancer stem cells that are unresponsive to current therapy. Our previous studies have shown how Nodal, an embryonic morphogen of the transforming growth factor-beta superfamily, is one of these critical factors that is reactivated in aggressive melanoma and resistant to conventional chemotherapy, such as dacarbazine. In the current study, we sought to determine whether BRAF inhibitor (BRAFi) therapy targeted Nodal-expressing tumor cells in uniquely matched unresectable stage III and IV melanoma patient samples before and after therapy that preceded their eventual death due to disease. The results demonstrate that BRAFi treatment failed to affect Nodal levels in melanoma tissues. Accompanying experiments in soft agar and in nude mice showed the advantage of using combinatorial treatment with BRAFi plus anti-Nodal monoclonal antibody to suppress tumor growth and metastasis. These data provide a promising new approach using front-line therapy combined with targeting a cancer stem cell-associated molecule-producing a more efficacious response than monotherapy.

Left-sided laterality of Merkel cell carcinoma in a German population: more than just sun exposure

BACKGROUND

Lateral distribution of cancer has been observed previously. Most evident is this laterality in ultraviolet (UV)-induced skin cancer, based on an unequally distributed UV exposure.

OBJECTIVES

The aim of this study was to explore whether patients from Germany also show asymmetrical lateral distribution of Merkel cell carcinoma (MCC).

METHODS

In total, 115 patients with MCC were studied for laterality of the primary tumour. Correlation of clinical variables with lateral distribution of MCC was investigated as well.

RESULTS

In 64/115 (55.7%) patients, primary tumours were present on the left side, in 37/115 (32.2%) on the right side, and in 14/115 (12.2%) in the midline (P < 0.0001). Excluding the latter localization occurrence of left-sided MCCs (64 of 101/63.4%) was significantly (P = 0.0072) more often observed (1.73-fold) when compared to right-sided tumours (37 of 101/36.6%). The excess of left-sided tumours was found on the head with a left-right ratio of 1.8, trunk of 8, arm of 1.2, and leg of 1.8. There was no significant association between laterality and gender, age, MCPyV status, and anatomic localization of primary tumours including the occurrence in sun-exposed sites.

CONCLUSIONS

Occurrence of left-sided MCCs was significantly more often observed when compared to right-sided tumours. Laterality was not associated with tumour presentation at chronically ultraviolet-exposed sites. Hence, the reason for laterality in MCC remains obscure, but likely goes beyond UV exposure.

Plasticity underlies tumor progression: role of Nodal signaling

The transforming growth factor beta (TGFβ) superfamily member Nodal is an established regulator of early embryonic development, with primary roles in endoderm induction, left-right asymmetry, and primitive streak formation. Nodal signals through TGFβ family receptors at the plasma membrane and induces signaling cascades leading to diverse transcriptional regulation. While conceptually simple, the regulation of Nodal and its molecular effects are profoundly complex and context dependent. Pioneering work by developmental biologists has characterized the signaling pathways, regulatory components, and provided detailed insight into the mechanisms by which Nodal mediates changes at the cellular and organismal levels. Nodal is also an important factor in maintaining pluripotency of embryonic stem cells through regulation of core transcriptional programs. Collectively, this work has led to an appreciation for Nodal as a powerful morphogen capable of orchestrating multiple cellular phenotypes. Although Nodal is not active in most adult tissues, its reexpression and signaling have been linked to multiple types of human cancer, and Nodal has emerged as a driver of tumor growth and cellular plasticity. In vitro and in vivo experimental evidence has demonstrated that inhibition of Nodal signaling reduces cancer cell aggressive characteristics, while clinical data have established associations with Nodal expression and patient outcomes. As a result, there is great interest in the potential targeting of Nodal activity in a therapeutic setting for cancer patients that may provide new avenues for suppressing tumor growth and metastasis. In this review, we evaluate our current understanding of the complexities of Nodal function in cancer and highlight recent experimental evidence that sheds light on the therapeutic potential of its inhibition.

Nodal signaling modulates the expression of Oct-4 via nuclear translocation of β-catenin in lung and prostate cancer cells

Nodal is a member of transforming growth factor beta (TGF-β) superfamily. Nodal promotes the self-renewal of human cancer stem cells (CSCs) and triggers carcinogenesis of human cancers via an autocrine manner through Smad2/3 pathway. In our study, generation of Nodal-overexpressed cancer cells was constructed, and the effect of Nodal on the stem cell marker Oct-4 was evaluated by overexpression or blocked Nodal/ALKs signaling pathway in non-small cell lung cancer cells A549 and prostate cancer cells PC3. Functionally, Nodal also increased the proliferation via the β-catenin nuclear translocation. This increase was attributed to GSK-3β dephosphorylating, and activin receptor-like kinase 4/7 (ALK4/7) played a major role in human cancer cells. Our study provides a positive understanding of Nodal function in cancer cells and suggests a potential novel target for clinical therapeutic research.

Overview of Transforming Growth Factor β Superfamily Involvement in Glioblastoma Initiation and Progression

Glioblastoma, also known as glioblastoma multiforme (GBM), is the most aggressive of human brain tumors and has a stunning progression with a mean survival of one year from the date of diagnosis. High cell proliferation, angiogenesis and/or necrosis are histopathological features of this cancer, which has no efficient curative therapy. This aggressiveness is associated with particular heterogeneity of the tumor featuring multiple genetic and epigenetic alterations, but also with implications of aberrant signaling driven by growth factors. The transforming growth factor β (TGFβ) superfamily is a large group of structurally related proteins including TGFβ subfamily members Nodal, Activin, Lefty, bone morphogenetic proteins (BMPs) and growth and differentiation factor (GDF). It is involved in important biological functions including morphogenesis, embryonic development, adult stem cell differentiation, immune regulation, wound healing and inflammation. This superfamily is also considered to impact on cancer biology including that of GBM, with various effects depending on the member. The TGFβ subfamily, in particular, is overexpressed in some GBM types which exhibit aggressive phenotypes. This subfamily impairs anti-cancer immune responses in several ways, including immune cells inhibition and major histocompatibility (MHC) class I and II abolishment. It promotes GBM angiogenesis by inducing angiogenic factors such as vascular endothelial growth factor (VEGF), plasminogen activator inhibitor (PAI-I) and insulin- like growth factor-binding protein 7 (IGFBP7), contributes to GBM progression by inducing metalloproteinases (MMPs), "pro-neoplastic" integrins (αvβ3, α5β1) and GBM initiating cells (GICs) as well as inducing a GBM mesenchymal phenotype. Equally, Nodal promotes GICs, induces cancer metabolic switch and supports GBM cell proliferation, but is negatively regulated by Lefty. Activin promotes GBM cell proliferation while GDF yields immune-escape function. On the other hand, BMPs target GICS and induce differentiation and sensitivity to chemotherapy. This multifaceted involvement of this superfamily in GBM necessitates different strategies in anti-cancer therapy. While suppressing the TGFβ subfamily yields advantageous results, enhancing BMPs production is also beneficial.

A Digital PCR-Based Method for Efficient and Highly Specific Screening of Genome Edited Cells

The rapid adoption of gene editing tools such as CRISPRs and TALENs for research and eventually therapeutics necessitates assays that can rapidly detect and quantitate the desired alterations. Currently, the most commonly used assay employs “mismatch nucleases” T7E1 or “Surveyor” that recognize and cleave heteroduplexed DNA amplicons containing mismatched base-pairs. However, this assay is prone to false positives due to cancer-associated mutations and/or SNPs and requires large amounts of starting material. Here we describe a powerful alternative wherein droplet digital PCR (ddPCR) can be used to decipher homozygous from heterozygous mutations with superior levels of both precision and sensitivity. We use this assay to detect knockout inducing alterations to stem cell associated proteins, NODAL and SFRP1, generated using either TALENs or an “all-in-one” CRISPR/Cas plasmid that we have modified for one-step cloning and blue/white screening of transformants. Moreover, we highlight how ddPCR can be used to assess the efficiency of varying TALEN-based strategies. Collectively, this work highlights how ddPCR-based screening can be paired with CRISPR and TALEN technologies to enable sensitive, specific, and streamlined approaches to gene editing and validation.

Nodal Promotes Functional Luteolysis via Down-Regulation of Progesterone and Prostaglandins E2 and Promotion of PGF2α Synthetic Pathways in Mare Corpus Luteum

In the present work, we investigated the role of Nodal, an embryonic morphogen from the TGFβ superfamily in corpus luteum (CL) secretory activity using cells isolated from equine CL as a model. Expression pattern of Nodal and its receptors activin receptor A type IIB (ACVR2B), activin receptor-like kinase (Alk)-7, and Alk4, as well as the Nodal physiological role, demonstrate the involvement of this pathway in functional luteolysis. Nodal and its receptors were immune localized in small and large luteal cells and endothelial cells, except ACVR2B, which was not detected in the endothelium. Nodal mRNA in situ hybridization confirmed its transcription in steroidogenic and endothelial cells. Expression analysis of the aforementioned factors evidenced that Nodal and Alk7 proteins peaked at the mid-CL (P < .01), the time of luteolysis initiation, whereas Alk4 and ACVR2B proteins increased from mid- to late CL (P < .05). The Nodal treatment of luteal cells decreased progesterone and prostaglandin (PG) E2 concentrations in culture media (P < .05) as well as mRNA and protein of secretory enzymes steroidogenic acute regulatory protein, cholesterol side-chain cleavage enzyme, cytosolic PGE2 synthase, and microsomal PGE2 synthase-1 (P < .05). Conversely, PGF2α secretion and gene expression of PG-endoperoxidase synthase 2 and PGF2α synthase were increased after Nodal treatment (P < .05). Mid-CL cells cultured with PGF2α had increased Nodal protein expression (P < .05) and phosphorylated mothers against decapentaplegic-3 phosphorylation (P < .05). Finally, the supportive interaction between Nodal and PGF2α on luteolysis was shown to its greatest extent because both factors together more significantly inhibited progesterone (P < .05) and promoted PGF2α (P < .05) synthesis than Nodal or PGF2α alone. Our results neatly pinpoint the sites of action of the Nodal signaling pathway toward functional luteolysis in the mare.

Overexpression of Nodal induces a metastatic phenotype in pancreatic cancer cells via the Smad2/3 pathway

Metastasis is the major cause for the high mortality rate of pancreatic cancer. Human embryonic stem cell (hESC) associated genes frequently correlate with malignant disease progression. Recent studies have demonstrated that the embryonic protein Nodal, which plays a critical role during embryonic development, is re-expressed in several types of tumors and promotes cancers progression. However, little is known about the role of Nodal in pancreatic cancer. Here, we show that Nodal expression is upregulated in human pancreatic cancer tissues. Moreover, Nodal expression levels correlate well with the grade of pancreatic cancer differentiation. In addition, we present clear evidence that Nodal induces signal transduction through the Smad2/3-dependent pathway in vitro. Furthermore, we show that Nodal promotes pancreatic cancer cell migration and invasion, induces epithelial-mesenchymal transition (EMT) and enhances the expression of matrix metalloproteinase-2 (MMP2) and CXC chemokine receptor 4 (CXCR4). Using an in vivo liver metastasis model of pancreatic cancer, we observed that blocking Nodal signaling activity with the small-molecule inhibitor SB431542 decreases the number and size of liver metastases. Taken together, our results suggest that Nodal overexpression induces a metastatic phenotype in pancreatic cancer cells, and that targeting Nodal signaling may be a promising therapeutic strategy for pancreatic cancer.

New Anti-Nodal Monoclonal Antibodies Targeting the Nodal Pre-Helix Loop Involved in Cripto-1 Binding

Nodal is a potent embryonic morphogen belonging to the TGF-β superfamily. Typically, it also binds to the ALK4/ActRIIB receptor complex in the presence of the co-receptor Cripto-1. Nodal expression is physiologically restricted to embryonic tissues and human embryonic stem cells, is absent in normal cells but re-emerges in several human cancers, including melanoma, breast, and colon cancer. Our aim was to obtain mAbs able to recognize Nodal on a major CBR (Cripto-Binding-Region) site and to block the Cripto-1-mediated signalling. To achieve this, antibodies were raised against hNodal(44-67) and mAbs generated by the hybridoma technology. We have selected one mAb, named 3D1, which strongly associates with full-length rhNodal (KD 1.4 nM) and recognizes the endogenous protein in a panel of human melanoma cell lines by western blot and FACS analyses. 3D1 inhibits the Nodal-Cripto-1 binding and blocks Smad2/3 phosphorylation. Data suggest that inhibition of the Nodal-Cripto-1 axis is a valid therapeutic approach against melanoma and 3D1 is a promising and interesting agent for blocking Nodal-Cripto mediated tumor development. These findings increase the interest for Nodal as both a diagnostic and prognostic marker and as a potential new target for therapeutic intervention.

Targeting nodal in conjunction with dacarbazine induces synergistic anticancer effects in metastatic melanoma

Metastatic melanoma is a highly aggressive skin cancer with a poor prognosis. Despite a complete response in fewer than 5% of patients, the chemotherapeutic agent dacarbazine (DTIC) remains the reference drug after almost 40 years. More recently, FDA-approved drugs have shown promise but patient outcome remains modest, predominantly due to drug resistance. As such, combinatorial targeting has received increased attention, and will advance with the identification of new molecular targets. One attractive target for improving melanoma therapy is the growth factor Nodal, whose normal expression is largely restricted to embryonic development, but is reactivated in metastatic melanoma. In this study, we sought to determine how Nodal-positive human melanoma cells respond to DTIC treatment and to ascertain whether targeting Nodal in combination with DTIC would be more effective than monotherapy. A single treatment with DTIC inhibited cell growth but did not induce apoptosis. Rather than reducing Nodal expression, DTIC increased the size of the Nodal-positive subpopulation, an observation coincident with increased cellular invasion. Importantly, clinical tissue specimens from patients with melanomas refractory to DTIC therapy stained positive for Nodal expression, both in pre- and post-DTIC tumors, underscoring the value of targeting Nodal. In vitro, anti-Nodal antibodies alone had some adverse effects on proliferation and apoptosis, but combining DTIC treatment with anti-Nodal antibodies decreased cell growth and increased apoptosis synergistically, at concentrations incapable of producing meaningful effects as monotherapy.

IMPLICATIONS

Targeting Nodal in combination with DTIC therapy holds promise for the treatment of metastatic melanoma.

Activin/Nodal signalling in stem cells

Activin/Nodal growth factors control a broad range of biological processes, including early cell fate decisions, organogenesis and adult tissue homeostasis. Here, we provide an overview of the mechanisms by which the Activin/Nodal signalling pathway governs stem cell function in these different stages of development. We describe recent findings that associate Activin/Nodal signalling to pathological conditions, focusing on cancer stem cells in tumorigenesis and its potential as a target for therapies. Moreover, we will discuss future directions and questions that currently remain unanswered on the role of Activin/Nodal signalling in stem cell self-renewal, differentiation and proliferation.

Conformational features and binding affinities to Cripto, ALK7 and ALK4 of Nodal synthetic fragments

Nodal, a member of the TGF-β superfamily, is a potent embryonic morphogen also implicated in tumor progression. As for other TGF-βs, it triggers the signaling functions through the interaction with the extracellular domains of type I and type II serine/threonine kinase receptors and with the co-receptor Cripto. Recently, we reported the molecular models of Nodal in complex with its type I receptors (ALK4 and ALK7) as well as with Cripto, as obtained by homology modeling and docking simulations. From such models, potential binding epitopes have been identified. To validate such hypotheses, a series of mutated Nodal fragments have been synthesized. These peptide analogs encompass residues 44-67 of the Nodal protein, corresponding to the pre-helix loop and the H3 helix, and reproduce the wild-type sequence or bear some modifications to evaluate the hot-spot role of modified residues in the receptor binding. Here, we show the structural characterization in solution by CD and NMR of the Nodal peptides and the measurement of binding affinity toward Cripto by surface plasmon resonance. Data collected by both conformational analyses and binding measurements suggest a role for Y58 of Nodal in the recognition with Cripto and confirm that previously reported for E49 and E50. Surface plasmon resonance binding assays with recombinant proteins show that Nodal interacts in vitro also with ALK7 and ALK4 and preliminary data, generated using the Nodal synthetic fragments, suggest that Y58 of Nodal may also be involved in the recognition with these protein partners.

Investigating microenvironmental regulation of human chordoma cell behaviour

The tumour microenvironment is complex and composed of many different constituents, including matricellular proteins such as connective tissue growth factor (CCN2), and is characterized by gradients in oxygen levels. In various cancers, hypoxia and CCN2 promote stem and progenitor cell properties, and regulate the proliferation, migration and phenotype of cancer cells. Our study was aimed at investigating the effects of hypoxia and CCN2 on chordoma cells, using the human U-CH1 cell line. We demonstrate that under basal conditions, U-CH1 cells express multiple CCN family members including CCN1, CCN2, CCN3 and CCN5. Culture of U-CH1 cells in either hypoxia or in the presence of recombinant CCN2 peptide promoted progenitor cell-like characteristics specific to the notochordal tissue of origin. Specifically, hypoxia induced the most robust increase in progenitor-like characteristics in U-CH1 cells, including increased expression of the notochord-associated markers T, CD24, FOXA1, ACAN and CA12, increased cell growth and tumour-sphere formation, and a decrease in the percentage of vacuolated cells present in the heterogeneous population. Interestingly, the effects of recombinant CCN2 peptide on U-CH1 cells were more pronounced under normoxia than hypoxia, promoting increased expression of CCN1, CCN2, CCN3 and CCN5, the notochord-associated markers SOX5, SOX6, T, CD24, and FOXA1 as well as increased tumour-sphere formation. Overall, this study highlights the importance of multiple factors within the tumour microenvironment and how hypoxia and CCN2 may regulate human chordoma cell behaviour.