Original Article

Oncogene (2007) 26, 4833–4841; doi:10.1038/sj.onc.1210286; published online 12 February 2007

Suppressor of cytokine signaling 3 (SOCS3) limits damage-induced crypt hyper-proliferation and inflammation-associated tumorigenesis in the colon

R J Rigby1, J G Simmons1, C J Greenhalgh2, W S Alexander3 and P K Lund1

  1. 1Department of Cell and Molecular Physiology, University of North Carolina, Chapel Hill, NC, USA
  2. 2Cancer and Haematology Division, Walter and Eliza Hall Institute of Medical Research, Victoria, Australia
  3. 3Division of Autoimmunity and Transplantation, Walter and Eliza Hall Institute of Medical Research, Victoria, Australia

Correspondence: Dr RJ Rigby, Department of Cell and Molecular Physiology, University of North Carolina at Chapel Hill, Rm 6336, MBRB, CB.7545, 103, Mason Farm Road, Chapel Hill, NC 27599, USA. E-mail: rachael_rigby@med.unc.edu

Received 8 September 2006; Revised 7 December 2006; Accepted 7 December 2006; Published online 12 February 2007.

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Abstract

Intestinal injury or chronic inflammation induce cytokines that promote crypt regeneration and mucosal repair. If excessive or prolonged, such mechanisms may increase colon cancer risk. Factors that terminate or limit cytokine action in intestinal epithelial cells (IEC) may protect against crypt hyperplasia and neoplasia. We hypothesized that suppressor of cytokine signaling-3 (SOCS3) is such a factor. Mice with Vilin-promoter/Cre-recombinase (VC)-mediated IEC-specific SOCS3 gene disruption (VC/HO), WT/HO littermates with floxed but intact SOCS3 genes and VC/WT mice were studied. Colon was examined after acute dextran sodium sulfate (DSS)-induced mucosal injury or after azoxymethane (AOM) and chronic DSS. Signaling pathways were examined in colon, cultured IEC or colon cancer cell lines. VC/HO mice showed no basal phenotype. After acute DSS, VC/HO exhibited enhanced crypt proliferation and crypt hyperplasia and reduced transforming growth factor (TGF) beta expression in colon. Inflammation and mucosal damage were similar across genotypes. Following AOM/DSS, VC/HO mice had increased size, number and load of colonic tumors and increased STAT3 and nuclear factor-kappa B (NF-kappaB) activation in colon. In vitro, SOCS3 overexpression reduced proliferation, IL-6-mediated STAT3 activation and tumor necrosis factor (TNF) alpha-mediated NF-kappaB activation. We conclude that cytokine induction of SOCS3 normally provides an intrinsic mechanism to limit injury-induced crypt hyperproliferation and inflammation-associated colon cancer by regulating both STAT3 and NF-kappaB pathways.

Keywords:

SOCS3, colon, cancer, mouse model