Notch-1 inhibits apoptosis in some transformed cells through incompletely understood mechanisms. Notch-1 can increase nuclear factor-kappa B (NF-kappaB) activity through a variety of mechanisms. Overexpression of cleaved Notch-1 in T-cell acute lymphoblastic leukemia cells activates NF-kappaB via interaction with the I kappa B kinase (IKK) signalosome.
View Article and Find Full Text PDFIndolent non-Hodgkin lymphomas are characterized by a prolonged phase that is typically followed by a clinical progression associated with an accelerated clinical course and short survival time. Previous studies have not identified a consistent cytogenetic or molecular abnormality associated with transformation. The development of a transformed phenotype, evolving from the original low-grade component, most likely depends on multiple genetic events, including the activation of synergistic dominant oncogenes and a loss of tumor suppressor gene functions.
View Article and Find Full Text PDFcAMP is a potent inhibitor of cell proliferation in a variety of cell lines. Downregulation of cyclin D1 and upregulation of the cell cycle inhibitor p27Kip1 are two mechanisms by which cAMP may induce a G1-arrest. Here we show that cAMP inhibits proliferation of cells that constitutively express cyclin D1 or are deficient for Rb, demonstrating that changes in these cell cycle regulators do not account for the cAMP-induced growth effects in mouse embryo fibroblasts (MEFs).
View Article and Find Full Text PDFForkhead transcription factors of the FOXO class are negatively regulated by PKB/c-Akt in response to insulin/IGF signalling, and are involved in regulating cell cycle progression and cell death. Here we show that, in contrast to insulin signalling, low levels of oxidative stress generated by treatment with H2O2 induce the activation of FOXO4. Upon treatment of cells with H2O2, the small GTPase Ral is activated and this results in a JNK-dependent phosphorylation of FOXO4 on threonine 447 and threonine 451.
View Article and Find Full Text PDFNotch receptor signaling has been implicated in cellular transformation. Notch-1 receptor expression is increased during the progression from cervical intraepithelial lesions (CIN) to invasive cervical carcinoma. Moreover, the main cellular localization of Notch-1 protein changes from cytoplasmic to nuclear with the transition from CIN III to microinvasive carcinoma.
View Article and Find Full Text PDFNotch receptors play a key role in several cellular processes including differentiation, proliferation, and apoptosis. This study investigated whether the activation of Notch signaling would affect the maturation of dendritic cells (DCs). Direct stimulation of Notch signaling in DCs with a peptide ligand induced DC maturation, similar to LPS: DCs up-regulated maturation markers, produced IL-12, lost endocytosis capacity, and became able to activate allogeneic T cells.
View Article and Find Full Text PDFTruncated Notch receptors have transforming activity in vitro and in vivo. However, the role of wild-type Notch signaling in neoplastic transformation remains unclear. Ras signaling is deregulated in a large fraction of human malignancies and is a major target for the development of novel cancer treatments.
View Article and Find Full Text PDFIn human papillomavirus (HPV) infected cervical epithelial cells the synthetic steroid dexamethasone inhibits radiation-induced apoptosis and increases the transcription of HPV E6/E7, enhancing p53 degradation. The aim of this study was to determine if suppression of apoptosis was mechanistically linked to changes in p53. HPV 16 E6 or E6/E7 expression vectors were transiently transfected into C4-1 HPV 18-positive cervical carcinoma cells to mimic the enhanced transcription following steroid treatment.
View Article and Find Full Text PDFVaccination with a peptide representing a CTL epitope from the human papillomavirus (HPV)16 E7 protein induces a specific CTL response that prevents the outgrowth of HPV16 E7-expressing tumors. In contrast, vaccination with a peptide encoding an adenovirus type 5 (Ad5) E1A CTL epitope results in CTL tolerance and enhanced growth of an Ad5 E1A-expressing tumor. It is unclear why these peptides induce such opposite effects.
View Article and Find Full Text PDFLoss of immunogenic epitopes by tumors has urged the development of vaccines against multiple epitopes. Recombinant DNA technologies have opened the possibility to develop multiepitope vaccines in a relatively rapid and efficient way. We have constructed four naked DNA-based multiepitope vaccines, containing CTL, Th cell, and B cell epitopes of the human papillomavirus type 16.
View Article and Find Full Text PDFAs a result of its transforming abilities, activated Ras is expressed in a great number of cancers. The ras mutation frequency varies between 95% in pancreatic cancer and 5% in breast cancer. In leukemia, the highest frequency (30%) is found in acute myeloid leukemia.
View Article and Find Full Text PDFMonaldi Arch Chest Dis
April 1998
An important role in the immune defense against deoxyribonucleic acid virus induced tumors is mediated by T-cells, as is evident from aetiological, animal model, and clinical data. In this review the most recent observations in this field are described for three prominent members of this family of viruses, namely human papillomavirus associated with human cervical cancer, human adenovirus associated with lung infections in humans and tumors in rodents, and simian virus 40 associated with rodent tumors and human mesothelioma, osteosarcoma and ependymoma.
View Article and Find Full Text PDFAs the nature of the T cell immune response is defined by T cell receptor recognition of small protein fragments, referred to as peptides, the identification of peptides would lead us to understanding and directing the T-cell-mediated immune response. Immunogenic peptides might be used for vaccination and activation of the immune reaction against cancer- and virus-infected cells. Additionally, the knowledge of immunogenic peptides was expected to lead to blocking of allergic reactions and autoimmune diseases.
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