Reference : Cell density dependent increase of constitutive signal transducers and activators of ...
Scientific journals : Article
Life sciences : Biochemistry, biophysics & molecular biology
http://hdl.handle.net/10993/773
Cell density dependent increase of constitutive signal transducers and activators of transcription 3 activity in melanoma cells is mediated by Janus kinases
English
Kreis, Stephanie mailto [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Life Science Research Unit >]
Munz, G. A. [Rheinisch - Westfälische Technische Hochschule Aachen - RWTH > Institute for Biochemistry]
Haan, Serge mailto [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Life Science Research Unit >]
Heinrich, P. C. [Rheinisch - Westfälische Technische Hochschule Aachen - RWTH > Institute for Biochemistry]
Behrmann, Iris mailto [University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Life Science Research Unit >]
2008
Molecular Cancer Research
American Association for Cancer Research, Inc. (AACR)
5
12
1331-41
Yes (verified by ORBilu)
International
1541-7786
1557-3125
[en] Janus Kinases ; Melanoma ; Phosphorylation ; STAT3 Transcription Factor ; Signal Transduction ; Skin Neoplasms ; src-Family Kinases ; Apoptosis ; Carcinoma, Hepatocellular ; Cell Count ; Cell Division ; Cell Survival ; Hela Cells ; Humans ; Liver Neoplasms
[en] Signal transducers and activators of transcriptions (STAT) are key mediators of cytokine signaling. Moreover, these transcription factors play a crucial role in oncogenic signaling where inappropriate and sustained activation of STATs, especially STAT3, is a trait of many different cancers and their derived cell lines. Constitutively active STAT3 has been reported to prevent programmed cell death and enhance cell proliferation, whereas the disruption of STAT3 signaling can inhibit tumor growth. The physiologic activation of STAT3 by cytokines has been well established; however, little is known about altered, stimulation-independent STAT3 activation. Here, we show that, in most but not all melanoma cell lines, STAT3 phosphorylation increased substantially with cell density and that this STAT3 was able to bind to DNA and to activate transcription. Inhibitor studies showed that the cell density-dependent STAT3 activation relies on Janus kinases (JAK) rather than Src kinases. Using a specific JAK inhibitor, sustained STAT3 activation was completely abrogated in all tested melanoma lines, whereas inhibition of Src or mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2 had no effect on constitutively tyrosine-phosphorylated STAT3 levels. Although STAT3 activation was completely blocked with JAK inhibitor I and to a lesser extent with the common JAK inhibitor AG490, only the latter compound markedly decreased proliferation and induced apoptosis. Taken together, variations in cell density can profoundly modify the extent of JAK-mediated persistent STAT3 phosphorylation; however, STAT3 activation was not sufficient to provide critical growth and survival signals in melanoma cell lines.
http://hdl.handle.net/10993/773
10.1158/1541-7786.MCR-07-0317

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