N-Terminal Truncation of Stat5a/b Circumvents PIAS3-Mediated Transcriptional Inhibition of Stat5 in Prostate Cancer Cells.
Summary of "N-Terminal Truncation of Stat5a/b Circumvents PIAS3-Mediated Transcriptional Inhibition of Stat5 in Prostate Cancer Cells."
Transcription factor Stat5a/b is critical for prostate cancer cell survival and for prostate xenograft tumor growth. In addition, the Stat5a/b signaling pathway may contribute to progression of organ-confined prostate cancer to castration-resistant and/or metastatic disease. Expression of nuclear Stat5a/b is clustered to high grade human prostate cancers, and nuclear Stat5a/b in primary prostate cancer predicts early disease recurrence after initial treatment. Here, we show by Western blotting and electromobility shift assay that Stat5a/b protein in human prostate cancer is N-terminally truncated. This short form of Stat5a/b is generated post-translationally in vivo in prostate cancer cells and is the predominant form of Stat5a/b that binds to DNA. We further demonstrate by mutagenesis and co-immunoprecipitations that the N-domain of Stat5a/b is required for binding to PIAS3, and that PIAS3 inhibits transcriptional activity of Stat5a/b in breast cancer cells but not in prostate cancer cells. Thus, the proteolytic cleavage of the N-terminus of Stat5a/b may be a mechanism by which Stat5 evades the transcriptional repression by PIAS3 in prostate cancer cells, and results in increased Stat5-driven gene expression and prostate cancer progression.
Department of Cancer Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107.
This article was published in the following journal.
Name: The international journal of biochemistry & cell biology
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/20854925
- DOI: http://dx.doi.org/10.1016/j.biocel.2010.09.008
Medical and Biotech [MESH] Definitions
The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activa
Cell Migration Inhibition
Phenomenon of cell-mediated immunity measured by in vitro inhibition of the migration or phagocytosis of antigen-stimulated LEUKOCYTES or MACROPHAGES. Specific CELL MIGRATION ASSAYS have been developed to estimate levels of migration inhibitory factors, immune reactivity against tumor-associated antigens, and immunosuppressive effects of infectious microorganisms.
Positive Transcriptional Elongation Factor B
A transcriptional elongation factor complex that is comprised of a heterodimer of CYCLIN-DEPENDENT KINASE 9 and one of several CYCLINS including TYPE T CYCLINS and cyclin K. It functions by phosphorylating the carboxy-terminal domain of RNA POLYMERASE II.
Proto-oncogene Proteins Pp60(c-src)
Membrane-associated tyrosine-specific kinases encoded by the c-src genes. They have an important role in cellular growth control. Truncation of carboxy-terminal residues in pp60(c-src) leads to PP60(V-SRC) which has the ability to transform cells. This kinase pp60 c-src should not be confused with csk, also known as c-src kinase.
An RNA polymerase II transcriptional inhibitor. This compound terminates transcription prematurely by selective inhibition of RNA synthesis. It is used in research to study underlying mechanisms of cellular regulation.
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