BACKGROUND: It has been shown that the expression of potassium channel tetramerization domain containing 12 (KCTD12) as a regulator of GABAB receptor signaling is reversely associated with gastrointestinal stromal tumors. In present study we examined the probable role of KCTD12 in regulation of several signaling pathways and chromatin remodelers in esophageal squamous cell carcinoma (ESCC).
METHODS: KCTD12 ectopic expression was done in KYSE30 cell line. Comparative quantitative real time PCR was used to assess the expression of stem cell factors and several factors belonging to the WNT/NOTCH and chromatin remodeling in transfected cells in comparison with non-transfected cells.
RESULTS: We observed that the KCTD12 significantly down regulated expression of NANOG, SOX2, SALL4, KLF4, MAML1, PYGO2, BMI1, BRG1, MSI1, MEIS1, EGFR, DIDO1, ABCC4, ABCG2, and CRIPTO1 in transfected cells in comparison with non-transfected cells. Migration assay showed a significant decrease in cell movement in ectopic expressed cells in comparison with non-transfected cells (p = 0.02). Moreover, KCTD12 significantly decreased the 5FU resistance in transfected cells (p = 0.01).
CONCLUSIONS: KCTD12 may exert its inhibitory role in ESCC through the suppression of WNT /NOTCH, stem cell factors, and chromatin remodelers and can be introduced as an efficient therapeutic marker.

AIMS: Head and neck squamous cell carcinoma (HNSCC) is the seventh most common cancer worldwide with considerable morbidity and mortality. Invasion and metastasis of HNSCC is a complex process involving multiple molecules and signaling pathways. Twist Family BHLH Transcription Factor 1 (TWIST1) and Mastermind-like 1 (MAML1) are essential in induction of epithelial-mesenchymal transition through direct regulation of implicated molecules in cellular adhesion, migration and invasion. Our aim in this study was to assess the clinical significance of MAML1 and TWIST1 expression in HNSCC, and elucidate the probable correlation between these genes to exhibit their possible associations with progression and metastasis of the disease.
METHODS: The gene expression profile of MAML1 and TWIST1 was assessed in fresh tumoral compared to distant tumor-free tissues of 55 HNSCC patients using quantitative real-time Polymerase chain reaction (PCR).
RESULTS: Significant overexpression of MAML1 and TWIST1 mRNA was observed in 49.1% and 38.2% (P ˂ 0.05) of tumor specimens, respectively. Overexpression of MAML1 was associated with vascular invasion (P = 0.048). Concomitant overexpression of MAML1 and TWIST1 was significantly correlated to each other (P = 0.004). Co-overexpression of the genes was significantly correlated to the various clinicopathological indices of poor prognosis including depth of tumor invasion (P < 0.01), lymphatic invasion and grade of tumor cell differentiation (P < 0.05).
CONCLUSIONS: Significant correlation between MAML1 and TWIST1 in HNSCC was revealed. This study was the first report elucidating MAML1 clinical relevance in HNSCC. These new findings suggest an oncogenic role for concomitant expression of MAML1 and TWIST1 genes in HNSCC invasion and metastasis.

Homeobox (HOX) transcription factors and NOTCH signaling pathway are critical regulators of stem cell functions, cell fate in development and homeostasis of gastrointestinal tissues. In the present study, we analyzed cross talk between NOTCH pathway and HOX genes through assessment of probable correlation betweenMAML1 and MEIS1 as the main transcription factor of NOTCH pathway and enhancer of HOX transcriptional machinery, respectively in esophageal squamous cell carcinoma (ESCC) patients. Fifty one ESCC cases were enrolled to assess the levels of Meis1 and Maml1 mRNA expression using real-time polymerase chain reaction (PCR). Only 3 out of 51 (5.9%) cases had MEIS1/MAML1 under expression and 2/51 (3.9%) cases had MEIS1/MAML1over expression. Nine out of 51 samples (17.6%) have shown MEIS1 under expression and MAML1 over expression. There was a significant correlation between MAML1and MEIS1mRNA expressions (p ≤ 0.05). There were significant correlations between MEIS1 under/MAML1 over expressed cases and tumor location (p = 0.05), tumor depth of invasion (p = 0.011), and sex (p = 0.04). Our results showed that MEIS1 may have a negative role in regulation of MAML1expression during the ESCC progression.

BACKGROUND: Notch signaling pathway is involved in different cellular and developmental processes including cell proliferation, differentiation and apoptosis. Mastermind like1 (MAML1) is a critical key transcription coactivator of this pathway. In this study, we aimed to examine MAML1 protein expression in esophageal squamous cell carcinoma (ESCC) and reveal its association with clinicopathological variables of the patients.
METHODS: Tumoral and their margin normal tissues from 56 ESCC patients were recruited for protein expression analysis using immunohistochemistry (IHC). Furthermore, MAML1 expression was analyzed in ESCC cell line KYSE-30 using immunocytochemistry.
RESULTS: Overexpression of MAML1 was detected in 59% of tumor samples. It was significantly associated with different indices of poor prognosis including depth of tumor invasion (P=0.026), grade of tumor differentiation (P=0.002), stage of tumor progression (P=0.004) and sex (P=0.027).
CONCLUSION: Beside the appearing evidences explaining MAML1 role in different cellular processes and its deviations in different malignancies and also based on its correlation with different clinicopathological variables of ESCC, MAML1 can be proposed as potentially novel molecular marker for ESCC progression and tumorigenesis as well as therapeutic target to inhibit and reverse progression and development of the disease.

Notch pathway was found to be activated in most glioblastomas (GBMs), underlining the importance of Notch in formation and recurrence of GBM. In this study, a Notch inhibitory peptide, dominant negative MAML (dnMAML), was conjugated to elastin-like polypeptide (ELP) for tumor targeted delivery. ELP is a thermally responsive polypeptide that can be actively and passively targeted to the tumor site by localized application of hyperthermia. This complex was further modified with the addition of a cell penetrating peptide, SynB1, for improved cellular uptake and blood-brain barrier penetration. The SynB1-ELP1-dnMAML was examined for its cellular uptake, cytotoxicity, apoptosis, cell cycle inhibition and the inhibition of target genes' expression. SynB1-ELP1-dnMAML inhibited the growth of D54 and U251 cells by inducing apoptosis and cell cycle arrest, especially in the presence of hyperthermia. Hyperthermia increased overall uptake of the polypeptide by the cells and enhanced the resulting pharmacological effects of dnMAML, showing the inhibition of targets of Notch pathway such as Hes-1 and Hey-L. These results confirm that dnMAML is an effective Notch inhibitor and combination with ELP may allow thermal targeting of the SynB1-ELP1-dnMAML complex in cancer cells while avoiding the dangers of systemic Notch inhibition.

In many cancers, aberrant Notch activity has been demonstrated to play a role in the initiation and maintenance of the neoplastic phenotype and in cancer stem cells, which may allude to its additional involvement in metastasis and resistance to therapy. Therefore, Notch is an exceedingly attractive therapeutic target in cancer, but the full range of potential targets within the pathway has been underexplored. To date, there are no small-molecule inhibitors that directly target the intracellular Notch pathway or the assembly of the transcriptional activation complex. Here, we describe an in vitro assay that quantitatively measures the assembly of the Notch transcriptional complex on DNA. Integrating this approach with computer-aided drug design, we explored potential ligand-binding sites and screened for compounds that could disrupt the assembly of the Notch transcriptional activation complex. We identified a small-molecule inhibitor, termed Inhibitor of Mastermind Recruitment-1 (IMR-1), that disrupted the recruitment of Mastermind-like 1 to the Notch transcriptional activation complex on chromatin, thereby attenuating Notch target gene transcription. Furthermore, IMR-1 inhibited the growth of Notch-dependent cell lines and significantly abrogated the growth of patient-derived tumor xenografts. Taken together, our findings suggest that a novel class of Notch inhibitors targeting the transcriptional activation complex may represent a new paradigm for Notch-based anticancer therapeutics, warranting further preclinical characterization. Cancer Res; 76(12); 3593-603. ©2016 AACR.

Corilagin is a natural plant polyphenol tannic acid with antitumor, anti-inflammatory, and anti-oxidative properties. However, the mechanisms of its actions are largely unknown. Our group reported that corilagin could induce cell inhibition in human breast cancer cell line MCF-7 and human liver hepatocellular carcinoma cell lines HepG2. We report here that corilagin inhibits cholangiocarcinoma (CCA) development through regulating Notch signaling pathway. We found that, in vitro, corilagin inhibited CCA cell proliferation, migration and invasion, promoted CCA cell apoptosis, and inhibited Notch1 and Notch signaling pathway protein expression. Co-immunoprecipitation was used to establish Notch intracellular domain (NICD) interaction with MAML1 and P300 in CCA. Importantly, corilagin reduced Hes1 mRNA level through inhibiting Hes1 promoter activity. In nude mice, corilagin inhibited CCA growth and repressed the expression of Notch1 and mTOR. These results indicate that corilagin may control CCA cell growth by downregulating the expression of Notch1. Therefore, our findings suggest that corilagin may have the potential to become a new therapeutic drug for human CCA.

Glioblastoma is the most common malignant brain tumor accounting for more than 54 % of all gliomas. Despite aggressive treatments, median survival remains less than 1 year. This might be due to the unavailability of effective molecular diagnostic markers and targeted therapy. Thus, it is essential to discover molecular mechanisms underlying disease by identifying dysregulated pathways involved in tumorigenesis. Notch signaling is one such pathway which plays an important role in determining cell fates. Since it is found to play a critical role in many cancers, we investigated the role of Notch genes in glioblastoma with an aim to identify biomarkers that can improve diagnosis. Using real-time PCR, we assessed the expression of Notch genes including receptors (Notch1, Notch2, Notch3, and Notch4), ligands (JAG1, JAG2, and DLL3), downstream targets (HES1 and HEY2), regulator Deltex1 (DTX1), inhibitor NUMB along with transcriptional co-activator MAML1, and a component of gamma-secretase complex APH1A in 15 formalin-fixed paraffin-embedded (FFPE) patient samples. Relative quantification was done by the 2(-ΔΔCt) method; the data are presented as fold change in gene expression normalized to an internal control gene and relative to the calibrator. The data revealed aberrant expression of Notch genes in glioblastoma compared to normal brain. More than 85 % of samples showed high Notch1 (P = 0.0397) gene expression and low HES1 (P = 0.011) and DTX1 (P = 0.0001) gene expression. Our results clearly show aberrant expression of Notch genes in glioblastoma which can be used as putative biomarkers together with histopathological observation to improve diagnosis, therapeutic strategies, and patient prognosis.

Notch signaling was associated with a variety of cancers but was not comprehensively studied in clear-cell renal cell carcinoma (ccRCC). We have in this study studied the genetic alteration (mutation and copy number variance) of Notch gene set in the Cancer Genome Atlas (TCGA) Kidney Renal Clear Cell Carcinoma (KIRC) database. We found that Notch pathway was frequently altered in ccRCC. The Notch gene set was genetically altered in 182 (44%) of the 415 ccRCC patients. CNV was the predominant type of alteration in most genes. Alterations in KAT2B and MAML1 occurred in 13% and 19% of patients, respectively, both of which were functionally active in ccRCC. Deletion of VHL was exclusively found in cases with Notch alteration. Overall survival was longer in ccRCC patients with altered-Notch pathway. The median survival was 90.41 months in Notch-altered cases and 69.15 in Notch-unaltered cases (P = 0.0404). The median disease free time was 89.82 months in Notch-altered cases and 77.27 months in in Notch-unaltered cases (P = 0.935). Conclusively, Notch signaling was altered in almost half of the ccRCC patients and copy number variances in MAML1 and KAT2B were predominant changes. These findings broadened our understanding of the role of Notch in ccRCC.

PURPOSE: Developmental pathways such as Wnt and Notch are involved in different cellular functions from the cell cycle regulation to self-renewal. Therefore, aberrations in these pathways may cause tumorigenesis. Msi1 has a critical regulatory role for the Wnt and Notch pathways. In the present study, we have assessed the probable correlation between the Msi1 and MAML1 in esophageal squamous cell carcinoma (ESCC) progression and metastasis.
METHODS: Levels of Msi1 and MAML1 mRNA expression in 51 ESCC patients were compared to the normal tissues using real-time polymerase chain reaction (PCR).
RESULTS: Nine out of 51 (17.6 %) cases had Msi1/MAML1 overexpression, and there was a significant correlation between such overexpressed cases and tumor location (p = 0.013).
CONCLUSIONS: We showed that there is not any direct correlation and feedback between the Msi1 and MAML1 in ESCC patients.

BACKGROUND AND AIMS: Pulmonary Mucoepidermoid carcinoma (MEC) accounts for 0.1-0.2% of all lung cancer. It occurred in the 3-78 years old, and 50% patients younger than 30. MEC has no standard treatment, but recently reports indicated MEC without epidermal growth factor receptor (EGFR) mutations sensitive to gefitinib.
OBJECTIVES: To explore a new standard treatment strategy for MEC, after reviewed literature related to MEC, we used Gefitinib to treatment a patient with EGFR-negative MEC, and observe its effects.
METHODS: 10-year-old boy was diagnosed with low-grade MEC by bronchial lung biopsy, EGFR gene mutation test was negative. Gefitinib was administered as neoadjuvant therapy at 125 mg daily.
RESULTS: The patient underwent right middle lobe, lower lobe resection and mediastinal lymph node dissection. After surgery, the patient had gained weight (5 kg) after 18 days of gefitinib therapy. A CT scan of the chest 1 month after surgical resection showed no recurrence, and followed for 22 months after treatment without tumour recurrence, suggesting that the patient was completely cured.
CONCLUSION: Gefitinib has potential to become a standard treatment for pulmonary MEC patients, including pediatric patients. However, the mechanisms need further investigation.

Activation of Notch signaling contributes to glioblastoma multiform (GBM) tumorigenesis. However, the molecular mechanism that promotes the Notch signaling augmentation during GBM genesis remains largely unknown. Identification of new factors that regulate Notch signaling is critical for tumor treatment. The expression levels of RND3 and its clinical implication were analyzed in GBM patients. Identification of RND3 as a novel factor in GBM genesis was demonstrated in vitro by cell experiments and in vivo by a GBM xenograft model. We found that RND3 expression was significantly decreased in human glioblastoma. The levels of RND3 expression were inversely correlated with Notch activity, tumor size, and tumor cell proliferation, and positively correlated with patient survival time. We demonstrated that RND3 functioned as an endogenous repressor of the Notch transcriptional complex. RND3 physically interacted with NICD, CSL, and MAML1, the Notch transcriptional complex factors, promoted NICD ubiquitination, and facilitated the degradation of these cofactor proteins. We further revealed that RND3 facilitated the binding of NICD to FBW7, a ubiquitin ligase, and consequently enhanced NICD protein degradation. Therefore, Notch transcriptional activity was inhibited. Forced expression of RND3 repressed Notch signaling, which led to the inhibition of glioblastoma cell proliferation in vitro and tumor growth in the xenograft mice in vivo. Downregulation of RND3, however, enhanced Notch signaling activity, and subsequently promoted glioma cell proliferation. Inhibition of Notch activity abolished RND3 deficiency-mediated GBM cell proliferation. We conclude that downregulation of RND3 is responsible for the enhancement of Notch activity that promotes glioblastoma genesis.

p53 and Notch-1 play important roles in breast cancer biology. Notch-1 inhibits p53 activity in cervical and breast cancer cells. Conversely, p53 inhibits Notch activity in T-cells but stimulates it in human keratinocytes. Notch co-activator MAML1 binds p53 and functions as a p53 co-activator. We studied the regulation of Notch signaling by p53 in MCF-7 cells and normal human mammary epithelial cells (HMEC). Results show that overexpression of p53 or activation of endogenous p53 with Nutlin-3 inhibits Notch-dependent transcriptional activity and Notch target expression in a dose-dependent manner. This effect could be partially rescued by transfection of MAML1 but not p300. Standard and quantitative co-immunoprecipitation experiments readily detected a complex containing p53 and Notch-1 in MCF-7 cells. Formation of this complex was inhibited by dominant negative MAML1 (DN-MAML1) and stimulated by wild-type MAML1. Standard and quantitative far-Western experiments showed a complex including p53, Notch-1, and MAML1. Chromatin immunoprecipitation (ChIP) experiments showed that p53 can associate with Notch-dependent HEY1 promoter and this association is inhibited by DN-MAML1 and stimulated by wild-type MAML1. Our data support a model in which p53 associates with the Notch transcriptional complex (NTC) in a MAML1-dependent fashion, most likely through a p53-MAML1 interaction. In our cellular models, the effect of this association is to inhibit Notch-dependent transcription. Our data suggest that p53-null breast cancers may lack this Notch-modulatory mechanism, and that therapeutic strategies that activate wild-type p53 can indirectly cause inhibition of Notch transcriptional activity.

Barrett's esophagus (BE) is defined as an incomplete intestinal metaplasia characterized generally by the presence of columnar and goblet cells in the formerly stratified squamous epithelium of the esophagus. BE is known as a precursor for esophageal adenocarcinoma. Currently, the cell of origin for human BE has yet to be clearly identified. Therefore, we investigated the role of Notch signaling in the initiation of BE metaplasia. Affymetrix gene expression microarray revealed that BE samples express decreased levels of Notch receptors (NOTCH2 and NOTCH3) and one of the the ligands (JAG1). Furthermore, BE tissue microarray showed decreased expression of NOTCH1 and its downstream target HES1. Therefore, Notch signaling was inhibited in human esophageal epithelial cells by expression of dominant-negative-Mastermind-like (dnMAML), in concert with MYC and CDX1 overexpression. Cell transdifferentiation was then assessed by 3D organotypic culture and evaluation of BE-lineage specific gene expression. Notch inhibition promoted transdifferentiation of esophageal epithelial cells toward columnar-like cells as demonstrated by increased expression of columnar keratins (K8, K18, K19, K20) and glandular mucins (MUC2, MUC3B, MUC5B, MUC17) and decreased expression of squamous keratins (K5, K13, K14). In 3D culture, elongated cells were observed in the basal layer of the epithelium with Notch inhibition. Furthermore, we observed increased expression of KLF4, a potential driver of the changes observed by Notch inhibition. Interestingly, knockdown of KLF4 reversed the effects of Notch inhibition on BE-like metaplasia. Overall, Notch signaling inhibition promotes transdifferentiation of esophageal cells toward BE-like metaplasia in part via upregulation of KLF4. These results support a novel mechanism through which esophageal epithelial transdifferentiation promotes the evolution of BE.

Aberrant activation of Notch signaling has an essential role in colorectal cancer (CRC) progression. Amplified in breast cancer 1 (AIB1), also known as steroid receptor coactivator 3 or NCOA3, is a transcriptional coactivator that promotes cancer cell proliferation and invasiveness. However, AIB1 implication in CRC progression through enhancing Notch signaling is unknown. In this study, we found that several CRC cell lines expressed high levels of AIB1, and knockdown of AIB1 decreased cell proliferation, colony formation and tumorigenesis of these CRC cells. Specifically, knockdown of AIB1 inhibited cell cycle progression at G1 phase by decreasing the mRNA levels of cyclin A2, cyclin B1, cyclin E2 and hairy and enhancer of split (Hes) 1. Furthermore, AIB1 interacted with Notch intracellular domain and Mastermind-like 1 and was recruited to the Hes1 promoter to enhance Notch signaling. Downregulation of AIB1 also decreased CRC cell invasiveness in vitro and lung metastasis in vivo. Besides that, knockout of AIB1 in mice inhibited colon carcinogenesis induced by azoxymethane/dextran sodium sulfate treatment. The mRNA levels of cyclin B1 and Hes5 were downregulated, but p27, ATOH1 and MUC2 were upregulated in the colon tumors from AIB1-deficient mice compared with those from wild-type mice. Thus, our results signify the importance of AIB1 in CRC and demonstrate that AIB1 promotes CRC progression at least in part through enhancing Notch signaling, suggesting that AIB1 is a potential molecular target for CRC treatment.

BACKGROUND: Notch signaling is one of the main involved pathways in cell differentiation and organogenesis, and its deregulation may lead to tumorigenesis. In this pathway, targeted to the CSL (CBF1, Suppressor of Hairless or Lag-1) complex, notch intracellular domain (NICD) releases corepressors and recruits MAML1 as coactivator triggering the activation of notch signaling transcription complex. Hairy enhance of split-1 (HES1) is one of the notch signaling target genes which is a basic helix-loop-helix (bHLH) transcription factor acting as a proliferation stimulator through the suppression of cell cycle inhibitors such as p27 and p21.
AIMS: In this study, we aimed to analyze the role of HES1 in the progression of esophageal squamous cell carcinoma (ESCC).
METHODS: Messenger RNA (mRNA) expression of HES1 in fresh tumoral tissues and their margin normal samples were assessed in 50 ESCC patients by real-time polymerase chain reaction (RT-PCR).
RESULTS: Thirteen out of 50 cases (26 %) had HES1 underexpression, while HES1 overexpression was observed only in 4 (8 %) samples. HES1 underexpression was significantly correlated with tumor depth of invasion (P = 0.035).
CONCLUSION: Although we have not observed any significant correlation between the HES1 expression and notch activation in ESCC, this study is the first report that elucidated the HES1 underexpression in ESCC and revealed its correlation with the invasiveness of ESCC.

Activation of the NOTCH receptors relies on their intracellular proteolysis by the gamma-secretase complex. This cleavage liberates the NOTCH intracellular domain (NIC) thereby allowing the translocation of NIC towards the nucleus to assemble into a transcriptional platform. Little information is available regarding the regulatory steps operating on NIC following its release from the transmembrane receptor up to its association with transcriptional partners. Interfering with these regulatory steps might potentially influences the nuclear outcome of NOTCH signalling. Herein, we exploited a reliable model to study the molecular events occurring subsequent to NOTCH1 cleavage. In pancreatic cancer cells, pulse of NOTCH1 activation led to increased expression of NOTCH target genes namely HES1 and c-MYC. We uncovered that, upon its release, the NOTCH1 intracellular domain, NIC1, undergoes a series of post-translational modifications that include phosphorylation. Most interestingly, we found that activation of the MEK/ERK pathway promotes HES1 expression. Inhibition of the gamma-secretase complex prevented the MEK/ERK-induced HES1 expression suggesting a NOTCH-dependent mechanism. Finally, higher levels of NIC1 were found associated with its transcriptional partners [CBF1, Su(H) and LAG-1] (CSL) and MASTERMIND-LIKE 1 (MAML1) upon MEK/ERK activation providing a potential mechanism whereby the MEK/ERK pathway promotes expression of NOTCH target genes. For the first time, our data exposed a signalling pathway, namely the MEK/ERK pathway that positively impacts on NOTCH nuclear outcome.

Recent advances in non-protein coding part of human genome analysis have discovered extensive transcription of large RNA transcripts that lack of coding protein function, termed long noncoding RNAs (lncRNAs). It is becoming evident that lncRNAs may be an important class of pervasive genes involved in carcinogenesis and metastasis. However, the biological and molecular mechanisms of lncRNAs in diverse diseases are not yet fully understood. Thus, it is anticipated that more efforts should be made to clarify the lncRNAs world. Moreover, accumulating studies have demonstrated that a class of lncRNAs are dysregulated in hepatocellular carcinoma(HCC) and closely related with tumorigenesis, metastasis, prognosis or diagnosis. In this review, we will briefly discuss the regulation and functional role of lncRNAs in HCC, therefore evaluating the potential of lncRNAs as prospective novel therapeutic targets in HCC.

Genomic, transcriptional, and proteomic analyses of brain tumors reveal subtypes that differ in pathway activity, progression, and response to therapy. However, a number of small molecule inhibitors under development vary in strength of subset and pathway-specificity, with molecularly targeted experimental agents tending toward stronger specificity. The Notch signaling pathway is an evolutionarily conserved pathway that plays an important role in multiple cellular and developmental processes. We investigated the effects of Notch pathway inhibition in glioma tumor-initiating cell (GIC, hereafter GIC) populations using γ secretase inhibitors. Drug cytotoxicity testing of 16 GICs showed differential growth responses to the inhibitors, stratifying GICs into responders and nonresponders. Responder GICs had an enriched proneural gene signature in comparison to nonresponders. Also gene set enrichment analysis revealed 17 genes set representing active Notch signaling components NOTCH1, NOTCH3, HES1, MAML1, DLL-3, JAG2, and so on, enriched in responder group. Analysis of The Cancer Genome Atlas expression dataset identified a group (43.9%) of tumors with proneural signature showing high Notch pathway activation suggesting γ secretase inhibitors might be of potential value to treat that particular group of proneural glioblastoma (GBM). Inhibition of Notch pathway by γ secretase inhibitor treatment attenuated proliferation and self-renewal of responder GICs and induces both neuronal and astrocytic differentiation. In vivo evaluation demonstrated prolongation of median survival in an intracranial mouse model. Our results suggest that proneural GBM characterized by high Notch pathway activation may exhibit greater sensitivity to γ secretase inhibitor treatment, holding a promise to improve the efficiency of current glioma therapy.

UNLABELLED: Early detection of circulation tumor cells (CTCs) in breast cancer patients has great clinical relevance. Currently, immunomagnetic microparticles enriched assays require Fe3O4 inner cores, making it difficult to improve sensitivity. In this study, we prepared magnetic nanoparticles with carbon-coated pure iron (Fe@C) acted as the core, Conjugating with EpCAM monoclonal antibody for immunomagnetic nanoparticles(IMPs). IMPs were used in conjunction with immunocytochemistry (ICC) to develop a refined immunomagnetic nanoparticles enriched assay (IMPEA) for detection of circulating tumor cells (CTCs) in breast cancer patients. Compared with nested RT-PCR, this method achieved the same sensitivity, but with a significantly reduced false-positive rate. This method will help find hidden micrometastases, establish clinical stage, and guide individual treatment post-surgery, suggesting potentially significant value in the clinic.
FROM THE CLINICAL EDITOR: This team of investigators prepared magnetic nanoparticles with carbon-coated pure iron as core and conjugated them with EpCAM monoclonal antibody to form immunomagnetic nanoparticles for circulating tumor cell (CTC) detection. Compared with nested RT-PCR, this method achieved the same sensitivity, but with a significantly reduced false-positive rate, paving the way to the development of a tool that enables enhanced detection of micrometastases and post-surgical treatment monitoring.

Glioblastoma (GBM) is a highly malignant primary tumor of the central nervous system originating in glial cells. GBM results in more years of life lost than any other cancer type. Low levels of Notch receptor expression correlates with prolonged survival in various high grade gliomas independent of other markers. Different downstream pathways of Notch receptors have been identified. We tested if the Notch/Deltex pathway, which is distinct from the canonical, CSL-mediated pathway, has a role in GBM. We show that the alternative or non-canonical Notch pathway functioning through Deltex1 (DTX1) mediates key features of glioblastoma cell aggressiveness. For example, DTX1 activates the RTK/PI3K/PKB and the MAPK/ERK mitotic pathways and induces anti-apoptotic Mcl-1. The clonogenic and growth potential of established glioma cells correlated with DTX1 levels. Microarray gene expression analysis further identified a DTX1-specific, MAML1-independent transcriptional program - including microRNA-21- which is functionally linked to the changes in tumor cell aggressiveness. Over-expression of DTX1 increased cell migration and invasion correlating to ERK activation, miR-21 levels and endogenous Notch levels. In contrast to high and intermediate expressors, patients with low DTX1 levels have a more favorable prognosis. The alternative Notch pathway via DTX1 appears to be an oncogenic factor in glioblastoma and these findings offer new potential therapeutic targets.

Although aberrant Notch activation contributes to leukemogenesis in T cells, its role in acute myelogenous leukemia (AML) remains unclear. Here, we report that human AML samples have robust expression of Notch receptors; however, Notch receptor activation and expression of downstream Notch targets are remarkably low, suggesting that Notch is present but not constitutively activated in human AML. The functional role of these Notch receptors in AML is not known. Induced activation through any of the Notch receptors (Notch1-4), or through the Notch target Hairy/Enhancer of Split 1 (HES1), consistently leads to AML growth arrest and caspase-dependent apoptosis, which are associated with B cell lymphoma 2 (BCL2) loss and enhanced p53/p21 expression. These effects were dependent on the HES1 repressor domain and were rescued through reexpression of BCL2. Importantly, activated Notch1, Notch2, and HES1 all led to inhibited AML growth in vivo, and Notch inhibition via dnMAML enhanced proliferation in vivo, thus revealing the physiological inhibition of AML growth in vivo in response to Notch signaling. As a novel therapeutic approach, we used a Notch agonist peptide that led to significant apoptosis in AML patient samples. In conclusion, we report consistent Notch-mediated growth arrest and apoptosis in human AML, and propose the development of Notch agonists as a potential therapeutic approach in AML.

Notch signaling is a highly conserved cell-cell communication pathway regulating normal development and tissue homeostasis. Aberrant Notch signaling represents an important oncogenic mechanism for T cell acute lymphoblastic leukemia (T-ALL), an aggressive subset of the most common malignant childhood cancer ALL. Therefore, understanding the molecular regulation of Notch signaling is critical to identify new approaches to block aberrant Notch oncogenic activity. The family of three MAML transcriptional coactivators is crucial for Notch signaling activation. The prototypic member MAML1 is the major coactivator that regulates Notch oncogenic activities in leukemic cells. However, the molecular basis underlying MAML1 coactivator function that contributes to Notch signaling remains unclear. In this study, we performed proteomic studies and identified DDX5, an ATP-dependent DEAD-box RNA helicase, as a component of the MAML1 protein complex. DDX5 interacts with MAML1 in vitro and in vivo, and is associated with the endogenous NOTCH1 transcription activation complex in human T-ALL leukemic cells. Lentivirus-mediated short-hairpin RNA knock-down of DDX5 resulted in decreased expression of Notch target genes, reduced cell proliferation and increased apoptosis in cultured human leukemic cells with constitutive activation of Notch signaling. Also, DDX5 depletion inhibited the growth of human leukemia xenograft in nude mice. Moreover, DDX5 is highly expressed in primary human T-ALL leukemic cells based on the analyses of Oncomine and GEO databases, and Immunohistochemical staining. Our overall findings revealed a critical role of DDX5 in promoting efficient Notch-mediated transcription in leukemic cells, suggesting that DDX5 might be critical for NOTCH1-mediated T-ALL pathogenesis and thus is a potential new target for modulating the Notch signaling in leukemia.

Mastermind-like 1 (MAML1) is a transcriptional coregulator of activators in various signaling pathways, such as Notch, p53, myocyte enhancer factor 2C (MEF2C) and beta-catenin. In earlier studies, we demonstrated that MAML1 enhanced p300 acetyltransferase activity, which increased the acetylation of Notch by p300. In this study, we show that MAML1 strongly induced acetylation of the transcription factor early growth response-1 (EGR1) by p300, and increased EGR1 protein expression in embryonic kidney cells. EGR1 mRNA transcripts were also upregulated in the presence of MAML1. We show that MAML1 physically interacted with, and acted cooperatively with EGR1 to increase transcriptional activity of the EGR1 and p300 promoters, which both contain EGR1 binding sites. Bioinformatics assessment revealed a correlation between p300, EGR1 and MAML1 copy number and mRNA alterations in renal clear cell carcinoma and p300, EGR1 and MAML1 gene alterations were associated with increased overall survival. Our findings suggest MAML1 may be a component of the transcriptional networks which regulate EGR1 target genes during nephrogenesis and could also have implications for the development of renal cell carcinoma.

Activating mutations in NOTCH1, an essential regulator of T cell development, are frequently found in human T cell acute lymphoblastic leukemia (T-ALL). Despite important advances in our understanding of Notch signal transduction, the regulation of Notch functions in the nucleus remains unclear. Using immunoaffinity purification, we identified NOTCH1 nuclear partners in T-ALL cells and showed that, beyond the well-characterized core activation complex (ICN1-CSL-MAML1), NOTCH1 assembles a multifunctional complex containing the transcription coactivator AF4p12, the PBAF nucleosome remodeling complex, and the histone demethylases LSD1 and PHF8 acting through their demethylase activity to promote epigenetic modifications at Notch-target genes. Remarkably, LSD1 functions as a corepressor when associated with CSL-repressor complex and as a NOTCH1 coactivator upon Notch activation. Our work provides new insights into the molecular mechanisms that govern Notch transcriptional activity and represents glimpse into NOTCH1 interaction landscape, which will help in deciphering mechanisms of NOTCH1 functions and regulation.

In order to investigate the prognostic value of circulating tumor cells (CTCs) in patients with metastatic breast cancer (MBC), the blood cells from 98 MBC patients and 60 controls were evaluated by RT-PCR to detect the presence of markers EpCAM, CK19, and hMAM. Peripheral blood was obtained from all patients with MBC before any systemic therapy. Immunofluorescence staining experiment was conducted on CTCs samples from 10 patients to investigate the coexpression of EpCAM, CK19, and hMAM. In addition, analyses were carried out for their correlation with patients' clinicopathologic features. EpCAM+, CK19+, and hMAM+ cells were detected in 50 (51.0 %), 43 (43.9 %), and 68 (69.4 %) of the 98 patients, respectively. Triple-marker-positive CTCs were detected in 86 of 98 (87.8 %) patients with a significantly higher rate than the control group. Among the 98 patients, 12 (12.2 %) patients were negative for three genes, 34 (34.7 %) positive for one gene, 29 (29.6 %) positive for any two genes, and 23 (23.5 %) positive for all three genes. Compared to single-marker detection, the triple combined marker detection exhibited significantly higher rate. Furthermore, the specificity of triple combined markers of serial test was 100 %. The expression of three genes was significantly correlated with lymph node metastasis, high histological grade, and high levels of serum CA153 and CEA. Double-immunofluorescence labeling confirmed the presence of following CTCs phenotypes: CK19+/hMAM+, CK19+/hMAM-, CK19-/hMAM+, CK19+/EpCAM+, CK19-/EpCAM+, CK19+/EpCAM-, hMAM+/EpCAM+, and hMAM+/EpCAM-. After 2 years of follow-up, the presence of CTCs with triple-marker positive in peripheral blood was an independent risk factor for reduced progression-free survival (PFS) and overall survival (OS), and the presence of CTCs before any chemotherapy predicts poor OS and PFS in patients with MBC.

The Notch signaling pathway is an evolutionarily conserved, intercellular signaling cascade. The Notch proteins are single-pass receptors that are activated upon interaction with the Delta (or Delta-like) and Jagged/Serrate families of membrane-bound ligands. Association of ligand-receptor leads to proteolytic cleavages that liberate the Notch intracellular domain (NICD) from the plasma membrane. The NICD translocates to the nucleus, where it forms a complex with the DNA-binding protein CSL, displacing a histone deacetylase (HDAc)-corepressor (CoR) complex from CSL. Components of a transcriptional complex, such as MAML1 and histone acetyltransferases (HATs), are recruited to the NICD-CSL complex, leading to the transcriptional activation of Notch target genes. The Notch signaling pathway plays a critical role in cell fate decision, tissue patterning, morphogenesis, and is hence regarded as a developmental pathway. However, if this pathway goes awry, it contributes to cellular transformation and tumorigenesis. There is mounting evidence that this pathway is dysregulated in a variety of malignancies, and can behave as either an oncogene or a tumor suppressor depending upon cell context. This chapter highlights the current evidence for aberration of the Notch signaling pathway in a wide range of tumors from hematological cancers, such as leukemia and lymphoma, through to lung, skin, breast, pancreas, colon, prostate, ovarian, brain, and liver tumors. It proposes that the Notch signaling pathway may represent novel target for cancer therapeutic intervention.

Maml1 is emerging as a coactivator of many signaling pathways, including the Notch and Wnt pathways. Targeting Maml1 in melanoma cells efficiently knocks down the downstream transcriptional repressors Hey1 and Hes1, resulting in melanoma cell senescence, cellular differentiation, and increased melanin production. Significantly, higher IFNβ and chemokine gene transcripts have been observed, together with increased STAT1 and decreased STAT3 and NF-κB signaling activities. Although decreased cell proliferation contributes to slower tumor growth in vivo, the depletion of NK and CD8(+) T cells in an shMaml1-B16 tumor carrier mouse leads to more rapid tumor growth than that observed in control shC002-B16 tumors. This result demonstrates that the knockdown of Maml1 transcription and function contributes to increased immune surveillance. The knockdown of Maml1 transcription in the human melanoma cell line M537 also results in senescence, IFNβ upregulation, increased chemokine gene expression, and greater NK and CD8(+) T cell migration in a transwell system. This study demonstrated that targeting Maml1-induced tumor cell senescence and differentiation may alter the tumor microenvironment and cytokine and chemokine profiles and may also promote innate and adaptive immune cell infiltration and function.

Angiosarcomas (ASs) represent a heterogeneous group of malignant vascular tumors that may occur spontaneously as primary tumors or secondarily after radiation therapy or in the context of chronic lymphedema. Most secondary ASs have been associated with MYC oncogene amplification, whereas the role of MYC abnormalities in primary AS is not well defined. Twenty-two primary and secondary ASs were analyzed by array-comparative genomic hybridization (aCGH) and by deep sequencing of small RNA libraries. By aCGH and subsequently confirmed by fluorescence in situ hybridization, MYC amplification was identified in three out of six primary tumors and in 8 out of 12 secondary AS. We have also found MAML1 as a new potential oncogene in MYC-amplified AS. Significant upregulation of the miR-17-92 cluster was observed in MYC-amplified AS compared to AS lacking MYC amplification and the control group (other vascular tumors, nonvascular sarcomas). Moreover, MYC-amplified ASs were associated with a significantly lower expression of thrombospondin-1 (THBS1) than AS without MYC amplification or controls. Altogether, our study implicates MYC amplification not only in the pathogenesis of secondary AS but also in a subset of primary AS. Thus, MYC amplification may play a crucial role in the angiogenic phenotype of AS through upregulation of the miR-17-92 cluster, which subsequently downregulates THBS1, a potent endogenous inhibitor of angiogenesis.

BACKGROUND: Epithelial-mesenchymal transition has recently attracted great attention in studying the malignant progression of cells through a converging pathway of oncogenesis and metastasis. Twist1 and Mastermind-like 1 (MAML1) are major regulators of EMT through different pathways. The aim of this study was to investigate the clinicopathological relevance of the expression of MAML-1 and Twist1 genes in esophageal squamous cell carcinoma (ESCC).
METHODS: Tumoral and corresponding normal tissues from 55 treatment-naive ESCC patients were subjected for expression analysis with quantitative real-time RT-PCR.
RESULTS: Overexpression of MAML-1 and Twist1 were significantly associated with lymph node metastasis and the surgical staging of tumor. Overexpression of Twist1 was associated with tumor depth of invasion. Mean relative expression (MRE) of MAML1 was significantly higher in patients with metastasis to lymph nodes (3.07 ± 0.51 vs. 0.86 ± 0.58, P = .008). MRE of Twist1 was significantly higher in patients with invasion of tumor to adventitia (T3, T4) (1.97 ± 0.29 vs. 0.39 ± 0.73, P = .036). In advanced stages of tumor (stage III, IV), a significantly higher MRE of Twist1 (2.47 ± 0.41 vs. 1.25 ± 0.36, P = .035) and MAML1 (3.05 ± 0.45 vs. 1.07 ± 0.59, P = .021) mRNA was observed.
CONCLUSIONS: We introduce Twist1 and MAML1 as new molecular markers of advanced tumor, which determine the characteristics and aggressive behavior of ESCC. Along with the emerging evidence of their role in different cellular processes and aberrations in various cancers, they are suggested as potentially interesting therapeutic targets to reverse a broad spectrum of functional aberrations that promote ESCC development.