Abstract
Neurotensin (NT), a gastrointestinal hormone, binds its receptor [neurotensin receptor (NTR)] to regulate the growth of normal and neoplastic intestinal cells; molecular mechanisms remain largely undefined. Glycogen synthase kinase-3 (GSK-3) regulates diverse cellular processes, including cell growth and apoptosis. Here, we show that NT induces the phosphorylation of GSK-3α/β in the human colon cancer cell line HT29, HCT116, or SW480, which possesses high-affinity NTR. The effect of NT was blocked by inhibitors of protein kinase C (PKC), but not by inhibitors of mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK1) or phosphatidylinositol-3 kinase, suggesting a predominant role for PKC in GSK-3β phosphorylation by NT. Pretreatment with Gö6976 (which inhibits PKCα and PKCβ1) or downregulation of endogenous PKCα or PKCβ1 blocked NT-mediated GSK-3β (but not GSK-3α) phosphorylation. Moreover, a selective PKCβ inhibitor, LY379196, reduced NT-mediated GSK-3β (but not GSK-3α) phosphorylation, suggesting a role for PKCβ1 in the NT-mediated phosphorylation of GSK-3β and an undefined kinase in the NT-mediated phosphorylation of GSK-3α. Treatment with NT or the GSK-3 inhibitor SB216763 increased the expression of cyclin D1, a downstream effector protein of GSK-3 and a critical protein for the proliferation of various cells. Our results indicate that NT uses PKC-dependent pathways to modulate GSK-3, which may play a role in the NT regulation of intestinal cell growth.
| Original language | English |
|---|---|
| Pages (from-to) | 781-787 |
| Number of pages | 7 |
| Journal | Neoplasia |
| Volume | 8 |
| Issue number | 9 |
| DOIs | |
| State | Published - 2006 |
Bibliographical note
Funding Information:Abbreviations: ECL, enhanced chemiluminescence; FBS, fetal bovine serum; GSK-3, glycogen synthase kinase-3; MBP, myelin basic protein; NT, neurotensin; NTR, neurotensin receptor; PI3-kinase, phosphatidylinositol-3 kinase; PMA, phorbol-12-myristate-13 acetate; PVDF, polyvinylidene difluoride; PKA, protein kinase A; PKB/Akt, protein kinase B; PKC, protein kinase C Address all correspondence to: B. Mark Evers, MD, Department of Surgery, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-0536. E-mail: mevers@utmb.edu 1This work was supported by grants R37 AG10885, RO1 DK48498, RO1 CA104748, and PO1 DK35608 from the National Institutes of Health. Received 24 March 2006; Revised 31 May 2006; Accepted 6 June 2006.
Keywords
- Cyclin D1
- GSK-3
- Intestinal cells
- Neurotensin
- PKC
ASJC Scopus subject areas
- Cancer Research
