Purpose: Neurotensin, a gut tridecapeptide, acts as a potent cellular mitogen for various colorectal and pancreatic cancers that possess high-affinity neurotensin receptors. Cytokine/chemokine proteins are increasingly recognized as important local factors that play a role in the metastasis and invasion of multiple cancers. The purpose of this study was to (a) determine the effect of neurotensin on cytokine/chemokine gene expression and cell migration in human cancer cells and (b) assess the effect of curcumin, a natural dietary product, on neurotensin-mediated processes.
Experimental Design: The human colorectal cancer, HCT116, was treated with neurotensin, with or without curcumin, and interleukin (IL)-8 expression and protein secretion was measured. Signaling pathways, which contribute to the effects of neurotensin, were assessed. Finally, the effect of curcumin on neurotensin-mediated HCT116 cell migration was analyzed.
Results: We show that neurotensin, acting through the native high-affinity neurotensin receptor, induced IL-8 expression in human colorectal cancer cells in a time- and dose-dependent fashion. This stimulation involves Ca2+-dependent protein kinase C, extracellular signal-regulated kinase–dependent activator protein-1, and extracellular signal-regulated kinase–independent nuclear factor-κB pathways. Curcumin inhibited neurotensin-mediated activator protein-1 and nuclear factor-κB activation and Ca2+ mobilization. Moreover, curcumin blocked neurotensin-stimulated IL-8 gene induction and protein secretion and, at a low concentration (i.e., 10 μmol/L), blocked neurotensin-stimulated colon cancer cell migration.
Conclusions: Neurotensin-mediated induction of tumor cell IL-8 expression and secretion may contribute to the procarcinogenic effects of neurotensin on gastrointestinal cancers. Furthermore, a potential mechanism for the chemopreventive and chemotherapeutic effects of curcumin on colon cancers may be through the inhibition of gastrointestinal hormone (e.g., neurotensin)–induced chemokine expression and cell migration.
- signal transduction
- GI cancers
Grant support: NIH grants R37 AG10885, R01 DK48498, and P01 DK35408.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
- Received April 19, 2006.
- Revision received June 13, 2006.
- Accepted July 13, 2006.