Expression Analysis of Fibronectin Type III Domain-Containing (FNDC) Genes in Inflammatory Bowel Disease and Colorectal Cancer.

Background: Fibronectin type III domain-containing () proteins fulfill manifold functions in tissue development and regulation of cellular metabolism. was described as anti-inflammatory factor, upregulated in inflammatory bowel disease (IBD). signaling includes direct cell-cell interaction as well as release of bioactive peptides, like shown for or . The G-protein-coupled receptor 116 () was found as a putative FNDC4 receptor. We here aim to comprehensively analyze the mRNA expression of , , , , , and in nonaffected and affected mucosal samples of patients with IBD or colorectal cancer (CRC).

Methods: Mucosa samples were obtained from 30 patients undergoing diagnostic colonoscopy or from surgical resection of IBD or CRC. Gene expression was determined by quantitative real-time PCR. In addition, expression data from publicly available Gene Expression Omnibus (GEO) data sets (GDS4296, GDS4515, and GDS5232) were analyzed.

Results: Basal mucosal expression revealed higher expression of and in the ileum compared to colonic segments. and were significantly upregulated in IBD. None of the investigated was differentially expressed in CRC, just trended to be upregulated. The GEO data set analysis revealed significantly downregulated and upregulated in microsatellite unstable (MSI) CRCs. The expression of and was independent of age and sex.

Conclusions: and may play a relevant role in the pathobiology of IBD, but none of the investigated is regulated in CRC. GPR116 may be upregulated in advanced or MSI CRC. Further studies should validate the altered expression results on protein levels and examine the corresponding functional consequences.