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Title: Transforming growth factor alpha activates Ha-Ras in human pancreatic cancer cells with Ki-ras mutations
Authors: Seufferlein, T
Van Lint, Johan
Liptay, S
Adler, G
Schmid, R M # ×
Issue Date: 23-Jun-1999
Series Title: Gastroenterology vol:116 issue:6 pages:1441-52
Abstract: BACKGROUND & AIMS: The aim of this study was to identify signaling pathways that mediate cell proliferation in response to a Ras-activating growth factor, transforming growth factor (TGF)-alpha, in two pancreatic cancer cell lines with constitutively active Ki-Ras, MiaPaCa-2, and Panc-1. METHODS: ERK1/-2- and p90(rsk) activation were determined by immune complex kinase assays. AP-1 and E74 activation were assessed in transient transfections using luciferase reporter plasmids. Ha-Ras activation was determined using a glutathione S-transferase fusion protein comprising the Ras-binding domain of Raf and by immunocytochemistry, growth by DNA synthesis and colony formation in softagar. RESULTS: TGF-alpha stimulated activation of ERK1/-2, which was dependent on MEK-1, but independent of PKC activity. TGF-alpha-induced activation of an AP-1 reporter plasmid also required MEK-1 and Ras activity. Using an E74 reporter plasmid, we demonstrate that TGF-alpha indeed activates Ras in both cell lines. In particular, TGF-alpha induced membrane translocation and activation of the Ras isoform Ha-Ras. Finally, TGF-alpha-stimulated DNA synthesis and clonal growth in soft agar were prevented by treatment of cells with a MEK-1 inhibitor or a Ras farnesyl transferase inhibitor. CONCLUSIONS: The Ha-Ras-ERK cascade plays an important role in TGF-alpha-induced growth of pancreatic cancer cells with activating Ki-ras mutations. Inhibitors of this cascade could constitute novel anticancer agents for pancreatic tumors.
URI: 
ISSN: 0016-5085
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Biochemistry Section (Medicine) (-)
Laboratory of Protein Phosphorylation and Proteomics
× corresponding author
# (joint) last author

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