title: Involvement of MAP-kinase, PI3-kinase and EGF-receptor in the stimulatory effect of Neurotensin on DNA synthesis in PC3 cells.
abstract: The mechanism by which neurotensin (NT) promotes the growth of prostate cancer epithelial cells is not yet defined. Here, androgen-independent PC3 cells, which express high levels of the type 1 NT-receptor (NTR1), are used to examine the involvement of epidermal growth factor receptor (EGFR), mitogen-activated protein kinases (ERK, SAPK/JNK and p38), PI3 kinase and PKC in the mitogenic effect of NT. NT dose dependently (0.1-30 nM) enhanced phosphorylation of EGFR, ERK and Akt, reaching maximal levels within 3 min as measured by Western blotting. These effects were associated with an accumulation of EGF-like substance(s) in the medium (assayed by EGFR binding) and a 2-fold increase in DNA synthesis (assayed by [3H]thymidine incorporation). The DNA synthesis enhancement by NT was non-additive with that of EGF. The NT-induced stimulation of EGFR/ERK/Akt phosphorylation and DNA synthesis was inhibited by EGFR-tyrosine kinase inhibitors (AG1478, PD153035), metallo-endopeptidase inhibitor phosphoramidon and by heparin, but not by neutralizing anti-EGF antibody. Thus, transactivation of EGFR by NT involved heparin-binding EGF (HB-EGF or amphiregulin) rather than EGF. The effects of NT on EGFR/ERK/Akt activation and DNA synthesis were attenuated by PLC-inhibitor (U73122), PKC-inhibitors (bisindolylmaleimide, staurosporine, rottlerin), MEK inhibitor (U0126) and PI3 kinase inhibitors (wortmannin, LY 294002). We conclude that NT stimulated mitogenesis in PC3 cells by a PKC-dependent ligand-mediated transactivation of EGFR, which led to stimulation of the Raf-MEK-ERK pathway in a PI3 kinase-dependent manner.
authors.affiliation: Department of Cellular and Molecular Physiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester 01655-0127, USA.
authors.forename: Sazzad
authors.initials: S
authors.lastname: Hassan
authors.forename: Paul R
authors.initials: PR
authors.lastname: Dobner
authors.forename: Robert E
authors.initials: RE
authors.lastname: Carraway
mesh_terms: D015153:Blotting, Western; D004273:DNA, Neoplasm / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D008297:Male; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009496:Neurotensin / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000473:pathology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism; D013936:Thymidine / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D004273:DNA, Neoplasm; D004791:Enzyme Inhibitors; D066246:ErbB Receptors; D008024:Ligands; D020928:Mitogen-Activated Protein Kinases; D009496:Neurotensin; D019869:Phosphatidylinositol 3-Kinases; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D019908:Proto-Oncogene Proteins c-raf; D013936:Thymidine; C494918:AKT1 protein, human