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Oncogene. 2008 Sep 18;27(42):5599-611. doi: 10.1038/onc.2008.169. Epub 2008 Jun 2.

Activation of NF-kappaB is required for mediating proliferative and antiapoptotic effects of progastrin on proximal colonic crypts of mice, in vivo.

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1
Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555-1043, USA.

Abstract

Mice overexpressing progastrin (PG) in intestinal mucosa (fatty acid-binding protein (Fabp)-PG mice) are at an increased risk of proximal colon carcinogenesis in response to azoxymethane. Here, we report a significant increase in the length of proximal colonic crypts in Fabp-PG mice, associated with potent antiapoptotic effects of PG, which likely contributed to the previously reported increase in colon carcinogenesis in Fabp-PG mice. Phosphorylation of kinase of IkappaBalpha (IKKalpha/beta), inhibitor of kappaB (IkappaB)alpha and p65NF-kappaB was significantly elevated in proximal colonic crypts of Fabp-PG versus wild-type mice, which was associated with degradation of IkappaBalpha and nuclear translocation/activation of p65. Surprisingly, distal colonic crypt cells were not as responsive to elevated levels of PG in Fabp-PG mice. Annexin II, recently described as a high-affinity receptor for PG, strongly co-localized with PG intracellularly and on basolateral membranes of proximal crypt cells, providing evidence that annexin-II binds PG in situ in colonic crypt cells. Proliferative and antiapoptotic effects of PG on proximal crypts of Fabp-PG mice were attenuated to wild-type levels, on treatment with NEMO peptide (an inhibitor of nuclear factor-kappaB (NF-kappaB) activation), demonstrating for the first time a critical role of NF-kappaB in mediating hyperproliferative affects of PG on colonic crypts of Fabp-PG mice, in vivo. Thus, downregulation of NF-kappaB may significantly reduce the increased risk of colon carcinogenesis in response to PG.

PMID:
18521082
PMCID:
PMC2891442
DOI:
10.1038/onc.2008.169
[Indexed for MEDLINE]
Free PMC Article
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