Dysregulation of IL6/IL6R-STAT3-SOCS3 signaling pathway in IBD-associated colorectal dysplastic lesions as compared to sporadic colorectal adenomas in non-IBD patients

Background: IL6-IL6R-STAT3-SOCS3 signaling pathway is known to play important roles in regulating intestinal epithelial homeostasis, in pathogenesis of inflammatory bowel disease (IBD), and in tumorigenesis of colorectal neoplasia. We studied the expressions of these factors in IBD-associated dysplasia and compared to sporadic colorectal adenomas in non-IBD individuals. Materials and methods: The expression of IL6, IL6R, STAT3, and SOCS3 within dysplastic as well as background non-dysplastic epithelial cells was evaluated by immunohistochemistry in 26 sporadic colorectal adenomas in non-IBD patients, 32 adenoma-like and 30 non-adenoma-like dysplastic lesions in IBD (41 ulcerative colitis, 21 Crohn's disease) patients. The level of expression of each factor was arbitrarily scored as 0, 1, 2, and 3. Results: In both IBD and non-IBD lesions, neoplastic epithelium showed a higher expression of all factors, except the IL6R, as compared to non-neoplastic epithelium. For non-neoplastic epithelium between IBD and non-IBD settings, the colitic epithelium showed a similar IL6, lower IL6R, higher STAT3, and higher SOCS3 expression. As compared to non-IBD adenomas, IBD-associated dysplasia showed a significantly lower IL6, lower IL6R, higher STAT3, and lower SOCS3 expression. Most notably, a parallel-elevation pattern of STAT3/SOCS3 expressions was seen in non-IBD adenomas but an inverse-expression pattern of STAT3/SOCS3 seen in IBD dysplastic lesions. No significant differences existed between adenoma-like and non-adenoma-like lesions. Conclusions: IL6/IL6R-STAT3-SOCS3 signaling pathway does not seem to be preferentially associated with IBD-associated dysplasia. However, the STAT3-SOCS3 interaction appears dysregulated in IBD, characterized by a loss of STAT3/SOCS3 balance,i.e., loss of the normal negative regulation of SOCS3.