Intestinal-type fibroblasts selectively influence proliferation rate and peptide synthesis in the murine entero-endocrine cell line STC-1.

The intestinal epithelium consists of enterocytes, endocrine cells, goblet cells and Paneth cells, which differentiate from pluripotent stem cells located at the crypt bases. The role of the epithelial-mesenchymal inter-actions has been well documented for the differentiation of enterocytes, but the mechanisms that control endocrine cell differentiation are poorly understood. We have cultured the intestinal endocrine cell line STC-1, which synthesizes most of the intestinal peptide hormones, in media conditioned by several subepithelial fibroblast cell lines from three distinct sites of intestine. The fibroblast Swiss 3T3 cell line was used as a non-intestinal control. Our results show that culture media from intestinal fibroblasts inhibit the proliferation rate of STC-1 cells, while those from Swiss 3T3 fibroblasts do not. As regards peptide hormone gene expression, Swiss 3T3-conditioned media have no effect, whereas media from intestinal fibroblasts variably affect cholecystokinin, glucagon, secretin and somatostatin mRNA levels. In particular, clonal subepithelial myofibroblasts do not exert the same effects as mixed subepithelial fibroblasts from homologous intestinal segment. Taken together, these results suggest that cultured fibroblasts of intestinal origin release soluble factors that inhibit STC-1 cell proliferation and modulate, in a region-specific manner, the expression of hormonal peptide genes in this nonspecialized endocrine cell line.