The mechanism of expression of gastric and intestinal character in epithelium of alimentary tract, and influence to prognosis of gastric cancer

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We established epithelial cell line from mouse glanduar stomach, and some fibroblast cell lines from mouse esophagus, forstomach, glandular stomach, jejunum and colon. By the immunofluorescence study epithelial cells were positive for tight junction protein zo-1 and cytokeratin-18 that is expressed only within simple (nonstratified) epithelium, but were not expressed specific markers for the stomach, such as MUC5AC, MUC6, pepsinogen, and H-K ATPase. All fibroblasts expressed vimentin filaments and α-SMA.To examine epithelial-mesenchymal interactions, we developed 3-dimensional coculture system using type I collagen gel. The epithelial cells formed thick branching cords that underwent progressive multifocal cavitation for 1 week when they cocultured with fibroblasts. That was the same phenomena as MontesanoR etc. observed in the renal cell line (MDCK) (1991 Cell 66: 697-711) But, formation of epithelial cells were not different even when coculture with another types of fibroblast. We speculated that fibroblasts lost their specificity during passage of culture.Hox is the homeobox gene which is necessary for development and differentiation of body, but the role of Hox gene in GI tract has not been elucidate. We investigated expression of HoxC8, HoxA5 mRNA in stomach, small. intestine and colon. RT PCR analysis revealed that Hox gene expressed only in small intestine and colon but not in stomach. We separated epithelium from mesenchyme of jejunum and investigate the expression of Hox gene separately, HoxC8 is express only in the mesenchyme of jejunum. HoxC8 must be specific and necessary for development of mesenchyme of jejunum.