Search results for "Proto-oncogene"
showing 10 items of 770 documents
Integrin cytoplasmic domain and pITAM compete for spleen tyrosine kinase binding
2019
ABSTRACTIn hematopoietic tissues cell-cell communication involves immunoreceptors and specialized cell adhesion receptors that both mediate intracellular signals. Spleen tyrosine kinase (Syk) is a non-receptor tyrosine kinase involved in the downstream signaling of both immunoreceptors tyrosine activation motif (ITAM) receptors and integrin family cell adhesion receptors. Both phosphorylated ITAM (pITAM) and integrins bind to the regulatory domain of Syk composed of two Src homology 2 (SH2) domains. The interaction with pITAM is mediated by binding of a specific phosphotyrosine to each of the SH2 domains, leading to conformational changes and Syk kinase activation. Integrins bind to the int…
The PVT-1 oncogene is a Myc protein target that is overexpressed in transformed cells
2007
The human PVT-1 gene is located on chromosome 8 telomeric to the c-Myc gene and it is frequently involved in the translocations occurring in variant Burkitt's lymphomas and murine plasmacytomas. It has been proposed that PVT-1 regulates c-Myc gene transcription over a long distance. To get new insights into the functional relationships between the two genes, we have investigated PVT-1 and c-Myc expression in normal human tissues and in transformed cells. Our findings indicate that PVT-1 expression is restricted to a relative low number of normal tissues compared to the wide distribution of c-Myc mRNA, whereas the gene is highly expressed in many transformed cell types including neuroblastom…
Gata4 Blocks Somatic Cell Reprogramming By Directly Repressing Nanog
2012
Abstract Somatic cells can be reprogrammed to induced pluripotent stem (iPS) cells by ectopic expression of the four factors Oct4, Klf4, Sox2, and Myc. Here, we investigated the role of Gata4 in the reprogramming process and present evidence for a negative role of this family of transcription factors in the induction of pluripotency. Coexpression of Gata4 with Oct4, Klf4, and Sox2 with or without Myc in mouse embryonic fibroblasts greatly impaired reprogramming and endogenous Nanog expression. The lack of Nanog upregulation was associated with a blockade in the transition from the initiation phase of reprogramming to the full pluripotent state characteristic of iPS cells. Addition of Nanog …
Effect of flupirtine on Bcl-2 and glutathione level in neuronal cells treated in vitro with the prion protein fragment (PrP106-126).
1997
Flupirtine, trade name Katadolon, is a centrally acting nonopioid analgesic that has recently been found to display cytoprotective activity in vitro and in vivo on neurons induced to undergo apoptosis. This report shows that the PrP106-126 fragment of the prion protein, which is the likely etiological agent for a series of encephalopathies, is toxic to cortical neurons in vitro. Simultaneously, PrP106-126 influences the molecular GSH content and the bcl-2 expression in neurons. Significant toxicity (32% reduction in cell viability) was observed at a concentration of 50 microM of the peptide after 9 days of incubation, while at higher concentrations toxicity increased to 70%. Neurotoxicity w…
Met inhibition revokes IFNγ-induction of PD-1 ligands in MET-amplified tumours
2019
BACKGROUND: Interferon-induced expression of programmed cell death ligands (PD-L1/PD-L2) may sustain tumour immuneevasion. Patients featuring MET amplification, a genetic lesion driving transformation, may benefit from anti-MET treatment. We explored if MET-targeted therapy interferes with Interferon-gamma modulation of PD-L1/PD-L2 in MET-amplified tumours.METHODS: PD-L1/PD-L2 expression and signalling pathways downstream of MET or Interferon-gamma were analysed in MET-amplified tumour cell lines and in patient-derived tumour organoids, in basal condition, upon Interferon-gamma stimulation, and after anti-MET therapy.RESULTS: PD-L1 and PD-L2 were upregulated in MET-amplified tumour cells up…
The abrogation of the HOXB7/PBX2 complex induces apoptosis in melanoma through the miR-221&222-c-FOS pathway.
2013
Cutaneous melanoma is the fastest increasing cancer worldwide. Although several molecular abnormalities have been associated with melanoma progression, the underlying mechanisms are still largely unknown and few targeted therapies are under evaluation. Here we show that the HOXB7/PBX2 dimer acts as a positive transcriptional regulator of the oncogenic microRNA-221 and -222. In addition, demonstrating c-FOS as a direct target of miR-221&222, we identify a HOXB7/PBX2→miR-221&222 →c-FOS regulatory link, whereby the abrogation of functional HOXB7/PBX2 dimers leads to reduced miR-221&222 transcription and elevated c-FOS expression with consequent cell death. Taking advantage of the treatment wit…
Chemically modified tetracyclines induce cytotoxic effects against J774 tumour cell line by activating the apoptotic pathway
2003
Here, we have studied the effects of chemically modified tetracyclines (CMTs) on apoptosis both at the level of the cytoplasmic proteolytic caspase cascade, and on Bcl-2 and c-myc mRNA expression in the J774 macrophage cell line. The results indicate that CMTs induce morphological changes consistent with apoptotic events, as clearly demonstrated both by the acridine orange and ethidium bromide staining, and by TUNEL and fragmentation ELISA assays. Furthermore, the analysis of the cell cycle by flow cytometry shows an evident apoptotic sub-G0G1 peak, without important modifications in the cell cycle distribution. CMTs induce programmed cell death (PCD) in a dose-dependent manner and CMT-8 is…
GD3 ganglioside directly targets mitochondria in a bcl-2-controlled fashion.
2000
Lipid and glycolipid diffusible mediators are involved in the intracellular progression and amplification of apoptotic signals. GD3 ganglioside is rapidly synthesized from accumulated ceramide after the clustering of death-inducing receptors and triggers apoptosis. Here we show that GD3 induces dissipation of DeltaPsim and swelling of isolated mitochondria, which results in the mitochondrial release of cytochrome c, apoptosis inducing factor, and caspase 9. Soluble factors released from GD3-treated mitochondria are sufficient to trigger DNA fragmentation in isolated nuclei. All these effects can be blocked by cyclosporin A, suggesting that GD3 is acting at the level of the permeability tran…
DNA damage-induced cell death by apoptosis
2006
Following the induction of DNA damage, a prominent route of cell inactivation is apoptosis. During the last ten years, specific DNA lesions that trigger apoptosis have been identified. These include O6-methylguanine, base N-alkylations, bulky DNA adducts, DNA cross-links and DNA double-strand breaks (DSBs). Repair of these lesions are important in preventing apoptosis. An exception is O6-methylguanine-thymine lesions, which require mismatch repair for triggering apoptosis. Apoptosis induced by many chemical genotoxins is the consequence of blockage of DNA replication, which leads to collapse of replication forks and DSB formation. These DSBs are thought to be crucial downstream apoptosis-tr…
Differentiation-associated apoptosis of neural stem cells is effected by Bcl-2 overexpression: impact on cell lineage determination
2001
Apoptosis is an integral part of neural development. To elucidate the importance of programmed cell death on cell lineage determination we utilized murine PCC7-Mzl cells, a model system for neural differentiation. Treatment of pluripotent PCC7-Mzl stem cells with 0.1 microM all-trans retinoic acid (RA) causes a cease of proliferation and an initiation of differentiation into neurons, glial cells and fibroblasts. Simultaneously, a fraction of the cell culture (ca. 25%) dies within 24 h by apoptosis. We transfected PCC7-Mzl cells with the human bcl-2 cDNA and generated PCC7-Mz-Bcl-2 cell lines expressing two- to tenfold higher levels of Bcl-2 than parental cells. Overexpression of Bcl-2 resul…