hes1-protein--human and Cell-Transformation--Neoplastic

Loss of BRCA1 p220 function often results in basal-like breast cancer (BLBC), but the underlying disease mechanism is largely opaque. In mammary epithelial cells (MECs), BRCA1 interacts with multiple proteins, including NUMB and HES1, to form complexes that participate in interstrand crosslink (ICL) DNA repair and MEC differentiation control. Unrepaired ICL damage results in aberrant transdifferentiation to a mesenchymal state of cultured, human basal-like MECs and to a basal/mesenchymal state in primary mouse luminal MECs. Loss of BRCA1, NUMB, or HES1 or chemically induced ICL damage in primary murine luminal MECs results in persistent DNA damage that triggers luminal to basal/mesenchymal transdifferentiation. In vivo single-cell analysis revealed a time-dependent evolution from normal luminal MECs to luminal progenitor-like tumor cells with basal/mesenchymal transdifferentiation during murine BRCA1 BLBC development. Growing DNA damage accompanied this malignant transformation.

Topics: Animals; BRCA1 Protein; Breast Neoplasms; Cell Differentiation; Cell Transdifferentiation; Cell Transformation, Neoplastic; Disease Models, Animal; DNA Damage; DNA Repair; Epithelial Cells; Female; HEK293 Cells; Humans; Mammary Glands, Animal; MCF-7 Cells; Membrane Proteins; Mice; Mice, Transgenic; Nerve Tissue Proteins; Transcription Factor HES-1; Transfection

Notch signaling pathway has been demonstrated to mediate radioresistance of several tumors. Our study aims to explore the function of Notch1/HES1 pathway in the radioresistance of colorectal cancer (CRC). The results demonstrated that expressions of Notch1 and Hes1 were up-regulated with the increasing irradiation dose. DAPT (N-[(3,5-difluorophenacetyl)acety1]-L-alanyl-2-phenyl]glycine-1,1-dimethylethyl ester) or si-Notch1 reduced expressions of Notch1 and Hes1, exacerbated irradiation-induced cell proliferation inhibition, and improved radiosensitivity of CRC cells. Moreover, DAPT or si-Notch1 increased radiation-induced DNA damage and attenuated radiation-triggered DNA-PK activity. Furthermore, xenograft in nude mice demonstrated that co-treated with DAPT and irradiation could inhibited tumor growth additively in vivo. Taken together, inhibition of Notch1/Hes1 signaling pathway enhances radiosensitivity of CRC cells, providing a potential therapeutic target to improve the therapeutic effect of radiotherapy for CRC patients.

Topics: Animals; Cell Proliferation; Cell Transformation, Neoplastic; Colorectal Neoplasms; Dipeptides; HT29 Cells; Humans; Mice; Radiation Tolerance; Receptor, Notch1; RNA, Small Interfering; Signal Transduction; Transcription Factor HES-1

Head and neck squamous cell carcinoma (HNSCC), a common cancer worldwide, is etiologically associated with tobacco use, high alcohol consumption, and high-risk human papillomaviruses (HPV). The Notch signaling pathway, which is involved in cell differentiation decisions with differential downstream targets and effects depending on tissue type and developmental stage, has been implicated in human HNSCC.. To assess the role of Notch signaling in HPV-positive and HPV-negative HNSCC, we utilized genetically engineered mouse (GEM) models for conventional keratinizing HNSCC, in which either HPV16 E6 and E7 oncoproteins or a gain-of-function mutant p53 are expressed, and in which we inactivated canonical Notch signaling via expression of a dominant negative form of MAML1 (DNMAML1), a required transcriptional coactivator of Notch signaling.. Loss of canonical Notch signaling increased tumorigenesis in both contexts and also caused an increase in nuclear β-catenin, a marker for increased tumorigenic potential. When combined with loss of canonical Notch signaling, HPV oncogenes led to the highest frequency of cancers overall and the largest number of poorly differentiated (high-grade) cancers.. These findings inform on the contribution of loss of canonical Notch signaling in head and neck carcinogenesis.

Topics: Animals; Cell Transformation, Neoplastic; Cell Transformation, Viral; Disease Models, Animal; DNA-Binding Proteins; Female; Gene Expression; Head and Neck Neoplasms; Human papillomavirus 16; Humans; Male; Mice; Mice, Transgenic; Molecular Targeted Therapy; Oncogene Proteins, Viral; Papillomavirus E7 Proteins; Papillomavirus Infections; Receptors, Notch; Repressor Proteins; Severity of Illness Index; Signal Transduction; Transcription Factor HES-1; Transcription Factors

Cancer stem cells (CSC) have attracted attention as therapeutic targets; however, CSC-targeting therapy may disrupt normal tissue homeostasis because many CSC molecules are also expressed by normal stem cells (NSC). Here, we demonstrate that NSC-specific and CSC-specific roles of the stem cell transcription factor Hes1 in the intestine enable the feasibility of a specific cancer therapy. Hes1 expression was upregulated in NSCs and intestinal tumors. Lineage-tracing experiments in adult mouse intestine revealed that Hes1 deletion in Lgr5

Topics: Animals; Cell Line, Tumor; Cell Transformation, Neoplastic; Humans; Intestinal Mucosa; Intestinal Neoplasms; Intestines; Mice; Mice, Inbred C57BL; Neoplastic Stem Cells; Transcription Factor HES-1

Perturbation of keratinocyte differentiation by E6/E7 oncoproteins of high-risk human papillomaviruses that drive oncogenic transformation of cells in squamocolumnar junction of the uterine cervix may confer "stem-cell like" characteristics. However, the crosstalk between E6/E7 and stem cell signaling during cervical carcinogenesis is not well understood. We therefore examined the role of viral oncoproteins in stem cell signaling and maintenance of stemness in cervical cancer.. Isolation and enrichment of cervical cancer stem-like cells (CaCxSLCs) was done from cervical primary tumors and cancer cell lines by novel sequential gating using a set of functional and phenotypic markers (ABCG2, CD49f, CD71, CD133) in defined conditioned media for assessing sphere formation and expression of self-renewal and stemness markers by FACS, confocal microscopy, and qRT-PCR. Differential expression level and DNA-binding activity of Notch1 and its downstream targets in CaCxSLCs as well as silencing of HPVE6/Hes1 by siRNA was evaluated by gel retardation assay, FACS, immunoblotting, and qRT-PCR followed by in silico and in vivo xenograft analysis.. CaCxSLCs showed spheroid-forming ability, expressed self-renewal and stemness markers Oct4, Sox2, Nanog, Lrig1, and CD133, and selectively overexpressed E6 and HES1 transcripts in both cervical primary tumors and cancer cell lines. The enriched CaCxSLCs were highly tumorigenic and did recapitulate primary tumor histology in nude mice. siRNA silencing of HPVE6 or Hes1 abolished sphere formation, downregulated AP-1-STAT3 signaling, and induced redifferentiation.. Our findings suggest the possible mechanism by which HPVE6 potentially regulate and maintain stem-like cancer cells through Hes1. Clin Cancer Res; 22(16); 4170-84. ©2016 AACR.

Topics: Animals; ATP-Binding Cassette Transporters; Biomarkers; Cell Line, Tumor; Cell Self Renewal; Cell Transformation, Neoplastic; Cell Transformation, Viral; Disease Models, Animal; Female; Gene Expression Regulation, Neoplastic; Genes, fos; Genes, jun; HeLa Cells; Humans; Mice; Mice, Inbred NOD; Models, Biological; Neoplastic Stem Cells; Oncogene Proteins, Viral; Protein Interaction Maps; Receptor, Notch1; RNA Interference; Signal Transduction; STAT3 Transcription Factor; Transcription Factor HES-1; Uterine Cervical Neoplasms

A small subpopulation of cancer cells with stem cell-like features might be responsible for tumour generation, progression, and chemoresistance. Hes1 influences the maintenance of certain stem cells and progenitor cells and the digestive systems. We found upregulated Hes1 in poorly differentiated cancer samples compared with well-differentiated tumour samples, and most of the adenocarcinomas exhibited significantly higher levels of Hes1 mRNA compared with that observed in matched normal colon samples. Moreover, Hes1 expression was found to be correlated with the expression of stem cell markers in colon cancer samples, and Hes1 upregulates the expression of stemness-related genes in colon cancer cells. In addition, Hes1 enhances the self-renewal properties of the stem-like cells by increasing the sizes of CD133+ cells and SP cells and the ability of tumour sphere formation. Additionally, the Hes1-overexpressing cells formed significantly larger and higher number of colonies, as determined through the colony and the soft agar assays. More importantly, Hes1 enhances the tumourigenicity of colon cancer cell lines in nude mice and exhibits a strong tumour-formation ability at a cell density of 1 × 10(3). Taken together, our data indicate that Hes1 induces stem-like cell self-renewal and increases the number of tumour-initiating cells in colon cancer.

Topics: AC133 Antigen; Adenocarcinoma; Animals; Antigens, CD; Basic Helix-Loop-Helix Transcription Factors; Cell Transformation, Neoplastic; Colonic Neoplasms; Flow Cytometry; Gene Expression Regulation, Neoplastic; Glycoproteins; HCT116 Cells; Homeodomain Proteins; Humans; Mice; Mice, Nude; Neoplasm Transplantation; Neoplastic Stem Cells; Peptides; RNA, Messenger; Spheroids, Cellular; Transcription Factor HES-1; Transplantation, Heterologous; Tumor Cells, Cultured; Up-Regulation

Biliary neuroendocrine tumours (NETs) are rare and mostly exist as a component of mixed adenoneuroendocrine carcinomas (MANECs). Although the NET component in biliary MANECs is generally more malignant and clinically more important to the prognosis than the ordinary adenocarcinomatous component, the histogenesis of biliary NET has not been clarified. In this study, the role of the Notch1-Hes1 signalling axis in the histogenesis of biliary NETs was examined.. Immunohistochemistry for Notch1, its ligand Jagged1 and Hes1 was performed using surgical specimens from 11 patients with biliary MANEC. Moreover, after the knock-down of Notch1 mRNA expression in a cholangiocarcinoma cell line, the expression of chromogranin A (a neuroendocrine marker) and Ascl1 (a neuroendocrine-inducing molecule inhibited by activated Hes1) was examined by quantitative PCR.. Histological examination revealed that the adenocarcinomatous components were predominately located at the luminal surface of the MANEC and the majority of stromal invasion involved NET components. Ordinary adenocarcinomas and non-neoplastic biliary epithelium constantly expressed Notch1, Jagged1 and Hes1, but the expression of Notch1 and Hes1 was decreased or absent in NET components, suggesting interference with the Notch1-Hes1 signalling axis in biliary NET. Moreover, in the cholangiocarcinoma cell line in which the expression of Notch1 mRNA was knocked down, the mRNA expression of Ascl1 and chromogranin A was increased.. The Notch1-Hes1 signalling axis suppresses neuroendocrine differentiation and maintains tubular/acinar features in adenocarcinoma and non-neoplastic epithelium in the biliary tree. Moreover, a disruption of this signalling axis may be associated with the tumourigenesis of NETs in biliary MANEC.

Topics: Adenocarcinoma; Basic Helix-Loop-Helix Transcription Factors; Biliary Tract Neoplasms; Carcinoma, Neuroendocrine; Cell Differentiation; Cell Line, Tumor; Cell Transformation, Neoplastic; Homeodomain Proteins; Humans; Immunohistochemistry; Receptor, Notch1; Signal Transduction; Transcription Factor HES-1; Transfection

CCAAT/enhancer binding protein α is one of the key transcription factors of the hepatocyte nuclear factors family, which plays a critical role in liver cell proliferation and differentiation. However, the role of CCAAT/enhancer binding protein α in hepatocarcinogenesis remains to be defined.. A recombinant adenovirus carrying the C/EBPα gene was constructed to determine its effect on hepatocarcinogenesis in vitro and in vivo.. We demonstrated that overexpression of CCAAT/enhancer binding protein α inhibited the tumourigenicity of Huh7 cells, re-established the expression of certain liver-specific genes and induced G0/G1 arrest. Overexpression of CCAAT/enhancer binding protein α significantly suppressed the proliferation of primary hepatocarcinogenesis cells and tumour associated fibroblasts in vitro. Additionally, intratumoural injection of adenovirus carrying the C/EBPα reduced the growth of subcutaneous hepatocarcinogenesis xenografts in nude mice. Systemic administration of adenovirus carrying the C/EBPα resulted in the eradication of orthotopic liver hepatocarcinogenesis nodules in nude mice. Further, up-regulation of CCAAT/enhancer binding protein α reduced the expression of Notch3, thereby suppressing Hes1 transactivation activity and leading to decreased p27 expression. Overexpression of Hes1 partially abolished the anti-proliferation effect of CCAAT/enhancer binding protein α on Huh7 cells.. These results suggested that the effect of CCAAT/enhancer binding protein α on hepatocarcinogenesis is partially through by reducing Notch3/Hes1/p27 cascades and CCAAT/enhancer binding protein α may possess a novel therapeutic potential for human hepatocarcinogenesis.

Topics: Adenoviridae; Animals; Basic Helix-Loop-Helix Transcription Factors; Carcinoma, Hepatocellular; CCAAT-Enhancer-Binding Protein-alpha; Cell Line, Tumor; Cell Proliferation; Cell Transformation, Neoplastic; G1 Phase Cell Cycle Checkpoints; Gene Expression Regulation, Neoplastic; Genetic Vectors; Homeodomain Proteins; Humans; Liver Neoplasms; Mice; Mice, Inbred BALB C; Neoplasm Transplantation; Proliferating Cell Nuclear Antigen; Receptor, Notch3; Receptors, Notch; Signal Transduction; Transcription Factor HES-1; Transfection

In animal studies, Notch1-signaling pathway plays an important role in the pancreatic embryogenesis by promoting pancreatic progenitor cells self-renewal and exocrine linage development. The persistent activation of Notch pathway could arrest the organ development and keep cells at an undifferentiated stage. Studies have shown that Notch1-signaling pathway is upregulated in invasive pancreatic ductal adenocarcinoma (PDAC). Here we examined the expression pattern of Notch1 and Hes1 in human fetal pancreatic tissues to elucidate the role of Notch1 in human pancreatic embryonic development. We also compared Notch1 expression in tissues from PDAC, chronic pancreatitis and pancreatic intraepithelial neoplasm. Our data show that Notch1/Hes1-signaling pathway is activated during early pancreatic embryogenesis and reaches the highest at birth. After pancreas is fully developed, Notch1/Hes1 pathway is inactivated even though Notch1 protein cell-surface expression is upregulated. We also showed that the expression of both Notch1 and Hes1 are present in 50% (33/66) of PDACs, but not in pancreatic intraepithelial neoplasms. These findings indicate that Notch1 activation is only apparent in late stage of pancreatic carcinogenesis, suggesting that treatment with Notch-signaling inhibitors including γ-secretase should be selectively used for PDACs with confirmed Notch1-signaling activation.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Basic Helix-Loop-Helix Transcription Factors; Carcinoma in Situ; Carcinoma, Pancreatic Ductal; Cell Transformation, Neoplastic; Child; Child, Preschool; Embryonic Development; Female; Fetus; Gene Expression Regulation, Developmental; Gene Expression Regulation, Neoplastic; Homeodomain Proteins; Humans; Infant; Male; Middle Aged; Pancreas; Pancreatic Neoplasms; Pancreatitis, Chronic; Pregnancy; Receptor, Notch1; Signal Transduction; Transcription Factor HES-1

Prostate carcinoma is among the most common causes of cancer-related death in men, representing 15% of all male malignancies in developed countries. Neuroendocrine differentiation (NED) has been associated with tumor progression, poor prognosis, and with the androgen-independent status. Currently, no successful therapy exists for advanced, castration-resistant disease. Because hypoxia has been linked to prostate cancer progression and unfavorable outcome, we sought to determine whether hypoxia would impact the degree of neuroendocrine differentiation of prostate cancer cells in vitro.. Exposure of LNCaP cells to low oxygen tension induced a neuroendocrine phenotype, associated with an increased expression of the transcription factor neurogenin3 and neuroendocrine markers, such as neuron-specific enolase, chromogranin A, and β3-tubulin. Moreover, hypoxia triggered a significant decrease of Notch 1 and Notch 2 mRNA and protein expression, with subsequent downregulation of Notch-mediated signaling, as shown by reduced levels of the Notch target genes, Hes1 and Hey1. NED was promoted by attenuation of Hes1 transcription, as cells expressing a dominant-negative form of Hes1 displayed increased levels of neuroendocrine markers under normoxic conditions. Although hypoxia downregulated Notch 1 and Notch 2 mRNA transcription and receptor activation also in the androgen-independent cell lines, PC-3 and Du145, it did not change the extent of NED in these cultures, suggesting that androgen sensitivity may be required for transdifferentiation to occur.. Hypoxia induces NED of LNCaP cells in vitro, which seems to be driven by the inhibition of Notch signaling with subsequent downregulation of Hes1 transcription.

Topics: Androgens; Basic Helix-Loop-Helix Transcription Factors; Cell Cycle Proteins; Cell Differentiation; Cell Line, Tumor; Cell Transformation, Neoplastic; Gene Expression Regulation, Neoplastic; Homeodomain Proteins; Humans; Hypoxia; Male; Nerve Tissue Proteins; Neuroendocrine Tumors; Oxygen; Prostatic Neoplasms; Receptor, Notch1; Receptor, Notch2; Transcription Factor HES-1

Cancer stem-like cell (CSC; also known as tumor initiating cell) is defined as a small subpopulation of cancer cells within a tumor and isolated from various primary tumors and cancer cell lines. CSCs are highly tumorigenic and resistant to anticancer treatments. In this study, we found that prolonged exposure to tumor necrosis factor alpha (TNFα), a major proinflammatory cytokine, enhances CSC phenotype of oral squamous cell carcinoma (OSCC) cells, such as an increase in tumor sphere-forming ability, stem cell-associated genes expression, chemo-radioresistance, and tumorigenicity. Moreover, activation of Notch1 signaling was detected in the TNFα-exposed cells, and suppression of Notch1 signaling inhibited CSC phenotype. Furthermore, we demonstrated that inhibition of a Notch downstream target, Hes1, led to suppression of CSC phenotype in the TNFα-exposed cells. We also found that Hes1 expression is commonly upregulated in OSCC lesions compared to precancerous dysplastic lesions, suggesting the possible involvement of Hes1 in OSCC progression and CSC in vivo. In conclusion, inflammatory cytokine exposure may enhance CSC phenotype of OSCC, in part by activating the Notch-Hes1 pathway.

Topics: Basic Helix-Loop-Helix Transcription Factors; Carcinoma, Squamous Cell; Cell Line, Tumor; Cell Transformation, Neoplastic; Homeodomain Proteins; Humans; Mouth Neoplasms; Neoplastic Stem Cells; Receptor, Notch1; Transcription Factor HES-1; Tumor Necrosis Factor-alpha

The activation of β-catenin signalling is a key step in intestinal tumorigenesis. Interplay between the β-catenin and Notch pathways during tumorigenesis has been reported, but the mechanisms involved and the role of Notch remain unclear.. Notch status was analysed by studying expression of the Notch effector Hes1 and Notch ligands/receptors in human colorectal cancer (CRC) and mouse models of Apc mutation. A genetic approach was used, deleting the Apc and RBP-J or Atoh1 genes in murine intestine. CRC cell lines were used to analyse the control of Hes1 and Atoh1 by β-catenin signalling.. Notch signalling was found to be activated downstream from β-catenin. It was rapidly induced and maintained throughout tumorigenesis. Hes1 induction was mediated by β-catenin and resulted from both the induction of the Notch ligand/receptor and Notch-independent control of the Hes1 promoter by β-catenin. Surprisingly, the strong phenotype of unrestricted proliferation and impaired differentiation induced by acute Apc deletion in the intestine was not rescued by conditional Notch inactivation. Hyperactivation of β-catenin signalling overrode the forced differention induced by Notch inhibition, through the downregulation of Atoh1, a key secretory determinant factor downstream of Notch. This process involves glycogen synthase kinase 3 β (GSK3β) and proteasome-mediated degradation. The restoration of Atoh1 expression in CRC cell lines displaying β-catenin activation was sufficient to increase goblet cell differentiation, whereas genetic ablation of Atoh1 greatly increased tumour formation in Apc mutant mice.. Notch signalling is a downstream target of β-catenin hyperactivation in intestinal tumorigenesis. However, its inhibition had no tumour suppressor effect in the context of acute β-catenin activation probably due to the downregulation of Atoh1. This finding calls into question the use of γ-secretase inhibitors for the treatment of CRC and suggests that the restoration of Atoh1 expression in CRC should be considered as a therapeutic approach.

Topics: Adenomatous Polyposis Coli Protein; Animals; Basic Helix-Loop-Helix Transcription Factors; beta Catenin; Cell Transformation, Neoplastic; Colorectal Neoplasms; DNA Mutational Analysis; DNA, Neoplasm; Genes, APC; Genes, Neoplasm; Homeodomain Proteins; Humans; Immunoglobulin J Recombination Signal Sequence-Binding Protein; Mice; Mice, Knockout; Neoplasm Proteins; Receptors, Notch; RNA Interference; Signal Transduction; Transcription Factor HES-1

Epidermal growth factor receptor (EGFR) overexpression and activation are hallmarks of non-small cell lung carcinoma (NSCLC). Although EGFR-targeted therapies are used, the prognosis of NSCLC remains poor. ADAM17 induces activation of the EGFR through ligand cleavage. However, we show that inhibition or knockdown of ADAM17 markedly reduces tumorigenesis and survival to a large part independently from EGFR ligand shedding in NSCLC cells. These findings strongly indicate additional oncogenic mechanisms regulated by ADAM17. We identified Notch1 signaling as an ADAM17-controlled pathway and a critical regulator of anchorage-independent growth by using both Notch1 shRNA and ectopic expression of the active intracellular Notch1 fragment. Strikingly, Notch1 knockdown led to a strong reduction of EGFR expression in all analyzed cell lines. Proliferation, survival, and colony formation of Notch1-deficient cells were insensitive to EGF stimulation. Moreover, targeting Notch1 or ADAM17 resulted in substantial cell death, whereas EGFR inhibition predominantly induced cell cycle arrest. Immunohistochemical analysis of primary human tissue revealed a significant correlation between ADAM17, Notch1 signaling, and high EGFR expression levels. In conclusion, this article describes a novel molecular circuitry in NSCLC, incorporating ADAM17 as a regulator of EGFR expression through the activation of Notch1. Due to their central role in tumorigenesis and survival of NSCLC cells, both ADAM17 and Notch1 constitute promising targets for the treatment of NSCLC.

Topics: ADAM Proteins; ADAM17 Protein; Animals; Basic Helix-Loop-Helix Transcription Factors; Carcinoma, Non-Small-Cell Lung; Cell Growth Processes; Cell Line, Tumor; Cell Survival; Cell Transformation, Neoplastic; Epidermal Growth Factor; ErbB Receptors; Homeodomain Proteins; Humans; Lung Neoplasms; Mice; Receptor, Notch1; Signal Transduction; Transcription Factor HES-1; Transplantation, Heterologous

The Notch signaling cascade plays a vital role in the proliferation and differentiation of cells during pancreatic development. Cell line experiments have suggested the involvement of Notch signaling in pancreatic endocrine tumorigenesis. We investigated the expression of NOTCH1, HES1, HEY1 and ASCL1 in pancreatic endocrine tumors and compared the data to tumor phenotype including hormone production, heredity, and WHO classification. Real-time quantitative PCR and immunohistochemistry were performed on samples of 26 pancreatic endocrine tumors. For comparison, 10 specimens of macroscopically normal pancreas were analyzed using immunohistochemistry. The subcellular localization of proteins was determined. Neither hormone production, nor heredity, or WHO classification was found to be associated with the expression of these proteins. There were discrepancies between mRNA and protein expression levels. All tumors displayed ASCL1 immunoreactivity. HES1 immunoreactivity was lacking altogether in 46% of the tumors, and in the remaining lesions its expression was weak and confined to the cytoplasm. In the nontumorous pancreatic endocrine cells, weak nuclear expression of HES1 as well as of HEY1 and NOTCH1 was observed. There was a significant positive correlation between NOTCH1 and HES1 mRNA levels, but no indication that HES1 was inhibiting ASCL1 transcription was found. No nuclear expression of HES1 was found in the tumors. This lack of nuclear expression of HES1 may contribute to the abundance of ASCL1 and to tumorigenesis in the endocrine pancreas.

Topics: Adult; Aged; Basic Helix-Loop-Helix Transcription Factors; Cell Cycle Proteins; Cell Differentiation; Cell Nucleus; Cell Proliferation; Cell Transformation, Neoplastic; Female; Gene Expression Regulation, Neoplastic; Homeodomain Proteins; Humans; Immunohistochemistry; Male; Middle Aged; Neoplasm Proteins; Pancreatic Neoplasms; Receptor, Notch1; Reverse Transcriptase Polymerase Chain Reaction; Signal Transduction; Transcription Factor HES-1

Notch receptors are conserved regulators of cell fate and have been implicated in the regulation of T cell differentiation and lymphomagenesis. However, neither the generality of Notch involvement in leukemia, nor the molecules with which Notch may interact have been clarified. Recently, we showed that transgenic mice expressing the constitutively active intracellular domain of Notch3 in thymocytes and T cells developed early and aggressive T cell neoplasias. Although primarily splenic, the tumors sustained features of immature thymocytes, including expression of pTalpha, a defining component of the pre T cell receptor, known to be a potent signaling complex provoking thymocyte survival, proliferation, and activation. Thus, enforced expression of Notch3, which is ordinarily down-regulated as thymocytes mature, may sustain pre T cell receptor expression, causing dysregulated hyperplasia. This hypothesis has been successfully tested in this article by the observation that deletion of pTalpha in Notch3 transgenic mice abrogates tumor development, indicating a crucial role for pTalpha in T cell leukemogenesis. Parallel observations were made in humans, in that all T cell acute lymphoblastic leukemias examined showed expression of Notch3 and of the Notch target gene HES-1, as well as of pTalpha a and b transcripts, whereas the expression of all these genes was dramatically reduced or absent in remission. Together, these results suggest that the combined expression of Notch3 and pTalpha sustains T cell leukemogenesis and may represent pathognomonic molecular features of human T-ALL.

Topics: Animals; Basic Helix-Loop-Helix Transcription Factors; Cell Transformation, Neoplastic; Child; Flow Cytometry; Gene Deletion; Gene Expression Regulation, Neoplastic; Homeodomain Proteins; Humans; Immunophenotyping; Leukemia-Lymphoma, Adult T-Cell; Leukemia, T-Cell; Lymph Nodes; Membrane Glycoproteins; Membrane Proteins; Mice; Mice, Transgenic; Proto-Oncogene Proteins; Receptor, Notch1; Receptor, Notch3; Receptor, Notch4; Receptors, Antigen, T-Cell; Receptors, Antigen, T-Cell, alpha-beta; Receptors, Cell Surface; Receptors, Notch; RNA, Messenger; Spleen; Thymus Gland; Transcription Factor HES-1; Transcription Factors

The cellular transcriptional repressor RBP-Jkappa associates with the Epstein-Barr virus nuclear antigens (EBNAs) determined to be essential for transformation of human primary B lymphocytes. It was demonstrated through genetic analysis that interaction between the viral transactivator EBNA2 and RBP-Jkappa is essential for EBV immortalization of primary B lymphocytes. We have shown that the association of RBP-Jkappa with intracellular NOTCH1 differs significantly in B and T cells. Immunoprecipitation analyses with antibodies to both the intracellular forms of NOTCH1 and to RBP-Jkappa demonstrated that little or no RBP-Jkappa is associated with NOTCH1 in B cell lines compared to the RBP-Jkappa associated with NOTCH1 in T cell lines and was further demonstrated in human primary lymphocytes. Additionally, EBNA2 can compete with intracellular NOTCH1 for binding to GST-RBP-Jkappa in vitro. Northern blot for the cellular gene hairy enhancer of split (HES1) demonstrated that HES1 is upregulated in the EBV transformed lymphoblastoid cells expressing high levels of EBNA2 and in a T cell line SupT1 overexpressing intracellular activated NOTCH1. Hence, EBNA2 may be able to compete for the available pool of RBP-Jkappa more effectively in human B cells than in T cells and provides a possible explanation for the ability of EBV to potently and efficiently infect and immortalize human B cells. Leukemia (2000) 14, 84-92.

Topics: B-Lymphocytes; Basic Helix-Loop-Helix Transcription Factors; Binding, Competitive; Cell Transformation, Neoplastic; DNA-Binding Proteins; Epstein-Barr Virus Nuclear Antigens; Homeodomain Proteins; Humans; Immunoglobulin J Recombination Signal Sequence-Binding Protein; Membrane Proteins; Nuclear Proteins; Protein Binding; Receptor, Notch1; Receptors, Cell Surface; T-Lymphocytes; Transcription Factor HES-1; Transcription Factors; Tumor Cells, Cultured; Viral Proteins