Ko CWS, Cuthbert RJ, Orsi NM, Brooke DA, Perry SL, Markham AF, Coletta PL, Hull MA. Lack of interleukin-4 receptor alpha chain-dependent signalling promotes azoxymethane-induced colorectal aberrant crypt focus formation in Balb/c mice.
J Pathol 2008;
214:603-9. [PMID:
18220315 DOI:
10.1002/path.2316]
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Abstract
Interleukin (IL)-4 receptor (IL-4R) alpha chain-dependent signalling by IL-4 and IL-13 promotes tumour growth and metastasis in mouse models of colorectal cancer. However, the role of IL-4R alpha-dependent signalling during the early, pre-malignant stages of colorectal carcinogenesis has not been investigated. Therefore, we investigated the effect of deletion of the IL-4R alpha gene on azoxymethane-induced colorectal aberrant crypt focus (ACF) multiplicity and size in Balb/c mice. IL-4R alpha(-/-) mice developed significantly more ACFs [median 8, inter-quartile range (IQR) 4-11.5; n = 9] than wild-type (WT) animals (median 4, IQR 1-6; n = 9; p = 0.04, Mann-Whitney U-test). There were significantly higher levels of IL-4 in serum from azoxymethane- and sham-treated IL-4R alpha(-/-) mice than WT animals, but no difference in serum IL-13 levels. In the absence of functional IL-4Rs, IL-13 can also signal via the IL-13R alpha2 receptor, leading to induction of transforming growth factor (TGF) beta, which has pro-tumourigenic activity at early stages of intestinal tumourigenesis. We found that mucosal TGFbeta mRNA levels and intestinal epithelial cell TGFbeta immunoreactivity were significantly higher in IL-4R alpha(-/-) mice than in WT animals. In summary, IL-4R alpha-dependent signalling has a protective, anti-neoplastic role during the post-initiation phase of azoxymethane-induced colorectal carcinogenesis in Balb/c mice. Our data should prompt thorough investigation of the role of IL-4R alpha-dependent signalling during human colorectal carcinogenesis, particularly as antagonism of IL-4R signalling represents a therapeutic strategy for asthma and other allergic diseases.
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