| 1. |
- Bahram, Fuad, et al.
(författare)
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Interferon-γ-induced p27KIP1 binds to and targets MYC for proteasome-mediated degradation.
- 2016
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 7:3, s. 2837-2854
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Tidskriftsartikel (refereegranskat)abstract
- The Myc oncoprotein is tightly regulated at multiple levels including ubiquitin-mediated protein turnover. We recently demonstrated that inhibition of Cdk2-mediated phosphorylation of Myc at Ser-62 pharmacologically or through interferon (IFN)-γ-induced expression of p27Kip1 (p27) repressed Myc's activity to suppress cellular senescence and differentiation. In this study we identified an additional activity of p27 to interfere with Myc independent of Ser-62 phosphorylation. p27 is required and sufficient for IFN-γ-induced turnover of Myc. p27 interacted with Myc in the nucleus involving the C-termini of the two proteins, including Myc box 4 of Myc. The C-terminus but not the Cdk2 binding fragment of p27 was sufficient for inducing Myc degradation. Protein expression data of The Cancer Genome Atlas breast invasive carcinoma set revealed significantly lower Myc protein levels in tumors with highly expressed p27 lacking phosphorylation at Thr-157 - a marker for active p27 localized in the nucleus. Further, these conditions correlated with favorable tumor stage and patient outcome. This novel regulation of Myc by IFN-γ/p27KIP1 potentially offers new possibilities for therapeutic intervention in tumors with deregulated Myc.
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| 2. |
- Bahram, Fuad, et al.
(författare)
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Posttranslational regulation of Myc function in response to phorbol ester/interferon-gamma-induced differentiation of v-Myc-transformed U-937 monoblasts
- 1999
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Ingår i: Blood. - 0006-4971 .- 1528-0020. ; 93:11, s. 3900-3912
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Tidskriftsartikel (refereegranskat)abstract
- The transcription factors of the Myc/Max/Mad network are important regulators of cell growth, differentiation, and apoptosis and are frequently involved in tumor development. Constitutive expression of v-Myc blocks phorbol ester (TPA)-induced differentiation of human U-937 monoblasts. However, costimulation with interferon-gamma (IFN-gamma) and TPA restores terminal differentiation and G1 cell-cycle arrest despite continuous expression of v-Myc. The mechanism by which TPA + IFN-gamma counteract v-Myc activity has not been unravelled. Our results show that TPA + IFN-gamma treatment led to an inhibition of v-Myc- and c-Myc-dependent transcription, and a specific reduction of v-Myc:Max complexes and associated DNA-binding activity, whereas the steady state level of the v-Myc protein was only marginally affected. In contrast, TPA + IFN-gamma costimulation neither increased the expression of Mad1 or other mad/mnt family genes nor altered heterodimerization or DNA-binding activity of Mad1. The reduced amount of v-Myc:Max heterodimers in response to treatment was accompanied by partial dephosphorylation of v-Myc and c-Myc. Phosphatase treatment of Myc:Max complexes lead to their dissociation, thus mimicking the effect of TPA + IFN-gamma. In addition to modulation of the expression of Myc/Max/Mad network proteins, posttranslational negative regulation of Myc by external signals may, therefore, be an alternative biologically important level of control with potential therapeutic relevance for hematopoietic and other tumors with deregulated Myc expression.
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| 3. |
- Bahram, Fuad, et al.
(författare)
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VEGF-mediated signal transduction in lymphatic endothelial cells
- 2010
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Ingår i: Pathophysiology : the official journal of the International Society for Pathophysiology / ISP. - : Elsevier BV. - 0928-4680. ; 17:4, s. 253-261
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Tidskriftsartikel (refereegranskat)abstract
- The VEGF family of angiogenic ligands consists of VEGFA, VEGFB, VEGFC, VEGFD and placenta growth factor, PlGF. These growth factors bind in an overlapping pattern to three receptor tyrosine kinases, denoted VEGFR1, VEGFR2 and VEGFR3. Originally, VEGFA (the prototype VEGF) was described as a master regulator of vascular endothelial cell biology in vitro and in vivo, transducing its effect through VEGFR2. VEGFA, VEGFB and PlGF bind to VEGFR1, which is a negative regulator of endothelial cell function at least during embryogenesis. VEGFC and VEGFD were identified as lymphatic endothelial factors, acting via VEGFR3. With time, the very clear distinction between the roles of the VEGF ligands in angiogenesis/lymphangiogenesis has given way for a more complex pattern. It seems that the biology of the different VEGFR2 and VEGFR3 ligands overlaps quite extensively and that both receptor types contribute to angiogenesis as well as lymphangiogenesis. This paradigm shift in our understanding is due to the access to more sophisticated reagents and techniques revealing dynamic and plastic expression of ligands and receptors in different physiological and pathological conditions. Moreover, knowledge on the important role of VEGF coreceptors, the neuropilins, in regulating the responsiveness to VEGF has changed our perception on the mechanism of VEGF signal transduction. This review will primarily focus on the properties of VEGR3, its signal transduction and the resulting biology.
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| 4. |
- Cetinkaya, Cihan, et al.
(författare)
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Combined IFN-gamma and retinoic acid treatment targets the N-Myc/Max/Mad1 network resulting in repression of N-Myc target genes in MYCN-amplified neuroblastoma cells
- 2007
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Ingår i: Molecular Cancer Therapeutics. - 1535-7163 .- 1538-8514. ; 6:10, s. 2634-2641
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Tidskriftsartikel (refereegranskat)abstract
- The MYCN protooncogene is involved in the control of cell proliferation, differentiation, and survival of neuroblasts. Deregulation of MYCN by gene amplification contributes to neuroblastoma development and is strongly correlated to advanced disease and poor outcome, emphasizing the urge for new therapeutic strategies targeting MYCN function. The transcription factor N-Myc, encoded by MYCN, regulates numerous genes together with its partner Max, which also functions as a cofactor for the Mad/Mnt family of Myc antagonists/transcriptional repressors. We and others have previously reported that IFN-gamma synergistically potentiates retinoic acid (RA)induced sympathetic differentiation and growth inhibition in neuroblastoma cells. This study shows that combined treatment of MYCN-amplified neuroblastorna cells with RA+IFN-gamma down-regulates N-Myc protein expression through increased protein turnover, up-regulates Mad1 mRNA and protein, and reduces N-Myc/Max heteroclimerization. This results in a shift of occupancy at the ornithine decarboxylase N-Myc/Mad1 target promoter in vivo from N-Myc/Max to Madl/Max predominance, correlating with histone H4 deacetylation, indicative of a chromatin structure typical of a transcriptionally repressed state. This is further supported by data showing that RA + IFN-gamma treatment strongly represses expression of N-Myc/Mad1 target genes ornithine decarboxylase and hTERT. Our results suggest that combined IFN-gamma and RA signaling can form a basis for new therapeutic strategies targeting N-Myc function for patients with high-risk, MYCN-amplified neuroblastoma.
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| 5. |
- Dimberg, Anna, et al.
(författare)
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Retinoic acid-induced cell cycle arrest of human myeloid cell lines is associated with sequential down-regulation of c-Myc and cyclin E and post-transcriptional upregulation of p27Kip1
- 2002
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Ingår i: Blood. - 0006-4971 .- 1528-0020. ; 99:6, s. 2199-2206
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Tidskriftsartikel (refereegranskat)abstract
- All-trans retinoic acid (ATRA) is a potential therapeutic agent for the treatment of hematopoietic malignancies, because of its function as an inducer of terminal differentiation of leukemic blasts. Although the efficacy of ATRA as an anticancer drug has been demonstrated by the successful treatment of acute promyelocytic leukemia (APL), the molecular mechanisms of ATRA-induced cell cycle arrest of myeloid cells have not been fully investigated. In this study, we show that the onset of ATRA-induced G0/G1 arrest of human monoblastic U-937 cells is linked to a sharp down-regulation of c-Myc and cyclin E levels and an increase in p21WAF1/CIP1 expression. This is followed by an increase in p27Kip1 protein expression due to enhanced protein stability. The importance of an early decrease in Myc expression for these events was demonstrated by the failure of a U-937 subline with constitutive exogenous expression of v-Myc to cell cycle arrest and regulate cyclin E and p27Kip1 in response to ATRA. Preceding the initiation of G1 arrest, a transient rise in retinoblastoma protein (pRb), p107, and cyclin A levels was detected. Later, a rapid fall in the levels of cyclins A and B and a coordinate dephosphorylation of pRb at Ser780, Ser795, and Ser807/811 coincided with the accumulation of cells in G1. These results thus identify a decrease in c-Myc and cyclin E levels and a posttranscriptional up-regulation of p27Kip1 as important early changes, and position them in the complex chain of events regulating ATRA-induced cell cycle arrest of myeloid cells.
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| 6. |
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| 7. |
- Klevebro, Susanna, et al.
(författare)
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Risk of SARS-CoV-2 exposure among hospital healthcare workers in relation to patient contact and type of care
- 2021
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Ingår i: Scandinavian Journal of Public Health. - : SAGE Publications. - 1403-4948 .- 1651-1905. ; 49:7, s. 707-712
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to assess prevalence of IgG antibodies to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and factors associated with seropositivity in a large cohort of healthcare workers (HCWs). Methods: From 11 May until 11 June 2020, 3981 HCWs at a large Swedish emergency care hospital provided serum samples and questionnaire data. Presence of IgG antibodies to SARS-CoV-2 was measured as an indicator of SARS-CoV-2 exposure. Results: The total seroprevalence was 18% and increased during the study period. Among the seropositive HCWs, 11% had been entirely asymptomatic. Participants who worked with COVID-19 patients had higher odds for seropositivity: adjusted odds ratio 1.96 (95% confidence intervals 1.59–2.42). HCWs from three of the departments managing COVID-19 patients had significantly higher seroprevalences, whereas the prevalence among HCWs from the intensive care unit (also managing COVID-19 patients) was significantly lower. Conclusions: HCWs in contact with SARS-CoV-2 infected patients had a variable, but on average higher, likelihood for SARS-CoV-2 infections.
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| 8. |
- Laytragoon-Lewin, Nongnit, et al.
(författare)
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Direct Effects of Pure Nicotine, Cigarette Smoke Extract, Swedish-type Smokeless Tobacco (Snus) Extract and Ethanol on Human Normal Endothelial Cells and Fibroblasts
- 2011
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 31:5, s. 1527-1534
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Tidskriftsartikel (refereegranskat)abstract
- The adverse health effects of cigarette smoking are well established including the increased risk of various types of cancer. In this study, the direct effects of ethanol, pure nicotine, cigarette smoke extract and Swedish type smokeless tobacco (Snus) extract on normal cells were investigated. Materials and Methods: Primary normal adult human endothelial cells and fibroblasts at early passage were used. Upon exposure to pure nicotine, cigarette smoke extract, Snus extract and ethanol, these cells were assessed for DNA synthesis, gene expression profile and cellular morphology. Results: Normal human fibroblasts and endothelial cells have unique gene expression profiles. The effects of treatment with ethanol and nicotine from different sources was more prominent in endothelial cells than fibroblasts. The combination of alterated gene expressions and strongly inhibited DNA synthesis was only detected in cells exposed to smoke extract. In the presence and absence of ethanol, pure nicotine and Snus extract induced abnormalities in the cytoplasm without any significant degree of cell death. With similar doses of nicotine and ethanol, the additional components in smoke extract had a dominant effect. The smoke extract induced vast cellular abnormalities and massive cell death. Conclusion: Cigarette smoke induced massive cell death and various abnormalities at cellular and molecular levels in surviving endothelial cells and fibroblasts. The combination of genomic alterations and the chronic inflammatory microenvironment induced from massive cell death, will potentially promote tumourigenesis and various diseases in cigarette smokers.
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| 9. |
- Matsumoto, Taro, et al.
(författare)
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Ninein Is Expressed in the Cytoplasm of Angiogenic Tip-Cells and Regulates Tubular Morphogenesis of Endothelial Cells
- 2008
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1079-5642 .- 1524-4636. ; 28, s. 2123-2130
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Tidskriftsartikel (refereegranskat)abstract
- Objective— Angiogenesis is an integral part of many physiologicalprocesses but may also aggravate pathological conditions suchas cancer. Development of effective angiogenesis inhibitorsrequires a thorough understanding of the molecular mechanismsregulating vessel formation. The aim of this project was toidentify proteins that regulate tubular morphogenesis of endothelialcells.Methods and Results— Phosphotyrosine-dependent affinity-purificationand mass spectrometry showed tyrosine phosphorylation of nineinduring tubular morphogenesis of endothelial cells. Ninein wasrecently identified as a centrosomal microtubule-anchoring protein.Our results show that ninein is localized in the cytoplasm inendothelial cells, and that it is highly expressed in the vasculaturein normal and pathological human tissues. Using embryoid bodiesas a model of vascular development, we found that ninein isabundantly expressed in the cytoplasm of endothelial cells duringsprouting angiogenesis, in particular in the sprouting tip-cell.In accordance, siRNA-dependent silencing of ninein in endothelialcells inhibited tubular morphogenesis.Conclusions— In this study, we show that ninein is expressedin developing vessels and in endothelial tip cells, and thatninein is critical for formation of the vascular tube. Thesedata strongly implicate ninein as an important new regulatorof angiogenesis.Proteins orchestrating morphological changes accompanying formationof the vascular tube constitute new targets for antiangiogenictherapy. In this study, we identify the microtubule-anchoringprotein ninein as an important new regulator of tubular morphogenesisof endothelial cells. This is the first report of a functionalrole of ninein in angiogenesis.
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| 10. |
- Mellberg, Sofie, et al.
(författare)
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Transcriptional profiling reveals a critical role for tyrosine phosphatase VE-PTP in regulation of VEGFR2 activity and endothelial cell morphogenesis.
- 2009
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Ingår i: The FASEB journal. - : Wiley. - 1530-6860 .- 0892-6638. ; 23:5, s. 1490-1502
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Tidskriftsartikel (refereegranskat)abstract
- To define molecular events accompanying formation of the 3-dimensional (3D) vascular tube, we have characterized gene expression during vascular endothelial growth factor (VEGF)-induced tubular morphogenesis of endothelial cells. Microarray analyses were performed comparing gene induction in growth-arrested, tube-forming endothelial cells harvested from 3D collagen cultures to that in proliferating endothelial cells cultured on fibronectin. Differentially expressed genes were clustered and analyzed for specific endothelial expression through publicly available datasets. We validated the contribution of one of the identified genes, vascular endothelial protein tyrosine phosphatase (VE-PTP), to endothelial morphogenesis. Silencing of VE-PTP expression was accompanied by increased VEGF receptor-2 (VEGFR2) tyrosine phosphorylation and activation of downstream signaling pathways. The increased VEGFR2 activity promoted endothelial cell cycle progression, overcoming the G(0)/G(1) arrest associated with organization into tubular structures in the 3D cultures. Proximity ligation showed close association between VEGFR2 and VE-PTP in resting cells. Activation of VEGFR2 by VEGF led to rapid loss of association, which was resumed with time in parallel with decreased receptor activity. In conclusion, we have identified genes, which may serve critical functions in formation of the vascular tube. One of these, VE-PTP, regulates VEGFR2 activity thereby modulating the VEGF-response during angiogenesis.
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