title: Activation of Stat3 by receptor tyrosine kinases and cytokines regulates survival in human non-small cell carcinoma cells.
abstract: Overexpression of receptor tyrosine kinases including the epidermal growth factor receptor (EGF-R) as well as nonreceptor tyrosine kinases, such as Src, have been implicated in the formation of human lung cancers. In addition, cytokines like interleukin-6 (IL-6) have been demonstrated to modulate lung cancer cell growth and elevated levels of IL-6 have been shown to be an adverse prognostic factor for patients with lung cancer. Despite a large body of evidence pointing to their potential importance, few direct studies into the role of signal transducers and activators of transcription (STAT) pathways in human lung cancer have been undertaken. Here we demonstrate that multiple nonsmall cell lung cancer cell lines demonstrate constitutive Stat3 DNA-binding activity. Stat3 DNA-binding activity is specifically upregulated by the addition of epidermal growth factor (EGF), IL-6, and hepatocyte-derived growth factor (HGF). Furthermore, the stimulation of Stat3 DNA-binding activity by EGF requires the activity of EGF-R tyrosine kinase as well as Src-kinase, while the upregulation of Stat3 activity by IL-6 or HGF requires only Src-kinase activity. Treatment of A549 lung cancer cells with PD180970 or SU6656, both pharmacological inhibitors of Src-kinase, resulted in reduced Src and Stat3 activity, cell cycle arrest in G2, and reduced viability of cells accompanied by induction of apoptosis. Treatment of Stat3-positive A549 and H358 cells with antisense Stat3 oligonucleotides results in complete loss of Stat3 DNA-binding activity and apoptosis, while Stat3-positive H1299 cells remained healthy. Finally, an adenoviral vector expressing a dominant-negative Stat3 isoform results in loss of Stat3 DNA-binding activity, apoptosis, and reduced cellular viability. These results demonstrate a role of Stat3 in transducing survival signals downstream of tyrosine kinases such as Src, EGF-R, and c-Met, as well as cytokines such as IL-6, in human nonsmall cell lung cancers.
authors.affiliation: Experimental Therapeutics, H. Lee Moffitt Cancer Center and Research Insitute, University of South Florida College of Medicine Tampa, FL 33612, USA.
authors.forename: Lanxi
authors.initials: L
authors.lastname: Song
authors.forename: James
authors.initials: J
authors.lastname: Turkson
authors.forename: James G
authors.initials: JG
authors.lastname: Karras
authors.forename: Richard
authors.initials: R
authors.lastname: Jove
authors.forename: Eric B
authors.initials: EB
authors.lastname: Haura
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D017209:Apoptosis; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000378:metabolism*; D002453:Cell Cycle; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival; D016207:Cytokines / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004815:Epidermal Growth Factor / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D016195:G2 Phase; D005799:Genes, Dominant; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008175:Lung Neoplasms / Q000378:metabolism*; D008954:Models, Biological; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D050796:STAT3 Transcription Factor; D013997:Time Factors; D015534:Trans-Activators / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D016207:Cytokines; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D015850:Interleukin-6; D016376:Oligonucleotides, Antisense; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D015534:Trans-Activators; D004815:Epidermal Growth Factor; D017228:Hepatocyte Growth Factor; D004247:DNA; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases