title: Src activation of Stat3 is an independent requirement from NF-kappaB activation for constitutive IL-8 expression in human pancreatic adenocarcinoma cells.
abstract: Human pancreatic tumors often overexpress the angiogenesis-promoting factor Interleukin 8 (IL-8), in part due to overexpression of NF-kappaB, a frequent occurrence in pancreatic adenocarcinoma. In this study, we demonstrate that reducing c-Src kinase activity, through either pharmacologic inhibition or small interfering RNA-targeted reduction of Src expression, significantly decreased IL-8 expression (P < 0.05) without affecting NF-kappaB-mediated transcription, but by decreasing phosphorylation of STAT3. To ascertain whether Src-mediated expression of IL-8 was dependent on STAT3, we used stable clones expressing a dominant-negative isoform of STAT3 that inhibits endogenous STAT3 phosphorylation and subsequent DNA binding and STAT3-mediated gene expression or a constitutively activated isoform of STAT3. IL-8 expression was significantly lower in clones expressing the dominant-negative isoform and significantly increased in clones expressing the activated isoform (P < 0.05 for both). Pharmacologic inhibition of NF-kappaB activity significantly reduced basal IL-8 expression and tumor necrosis factor-induced IL-8 expression (P < 0.05 for both), yet NF-kappaB activity was not dependent on Src. We therefore suggest that Src activation, through phosphorylation of STAT3, and NF-kappaB are all required for expression of IL-8 a critical angiogenic-promoting factor in pancreatic adenocarcinomas.
authors.affiliation: Department of Cancer Biology, Unit 179, The University of Texas M D Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030, USA.
authors.forename: Jose G
authors.initials: JG
authors.lastname: Trevino
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Gray
authors.forename: Steffan T
authors.initials: ST
authors.lastname: Nawrocki
authors.forename: Justin M
authors.initials: JM
authors.lastname: Summy
authors.forename: Donald P
authors.initials: DP
authors.lastname: Lesslie
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Evans
authors.forename: Tomi K
authors.initials: TK
authors.lastname: Sawyer
authors.forename: William C
authors.initials: WC
authors.lastname: Shakespeare
authors.forename: Stephanie S
authors.initials: SS
authors.lastname: Watowich
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Chiao
authors.forename: David J
authors.initials: DJ
authors.lastname: McConkey
authors.forename: Gary E
authors.initials: GE
authors.lastname: Gallick
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D017930:Genes, Reporter; D006801:Humans; D007150:Immunohistochemistry; D016209:Interleukin-8 / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D018613:Microscopy, Confocal; D016328:NF-kappa B / Q000378:metabolism*; D010190:Pancreatic Neoplasms / Q000378:metabolism* / Q000473:pathology; D010766:Phosphorylation; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000378:metabolism*
chemical_list: D016209:Interleukin-8; D016328:NF-kappa B; D034741:RNA, Small Interfering; D050796:STAT3 Transcription Factor; D008156:Luciferases; D016392:Proto-Oncogene Proteins pp60(c-src)