EXPRESSION OF MUC2 AND MUC3 MESSENGER-RNA IN HUMAN NORMAL, MALIGNANT,AND INFLAMMATORY INTESTINAL TISSUES

MUC2 and MUC3 are prominent mucin genes expressed in the human intesti ne. Using in situ hybridization with RNA probes, we examined the cellu lar distribution of MUC2 and MUC3 mRNA in normal, malignant, and infla mmatory human intestinal tissues. In normal small intestine and colon. MUC2 mRNA was expressed exclusively in goblet cells and occurred thro ughout the entire height of the mucosa. MUC3 mRNA was expressed by gob let and columnar cells but was restricted to the villous compartment o f the small intestine and the surface epithelium of the colon. Express ion of MUC2 and MUC3 mRNA were both markedly decreased in poorly, mode rately, and well-differentiated colon cancers but were preserved in mu cinous colon cancers. In ulcerative colitis and Crohn's colitis tissue s, MUC2 and MUC3 mRNA expression displayed a normal pattern regardless of whether the mucosa manifested active or quiescent inflammation. Th ese findings indicate that MUC2 is goblet cell-specific, whereas MUC3 is related to maturation of intestinal epithelial cells. In colon canc ers, the genetic regulation of MUC2 and MUC3 is different depending on the histological type of tumor. The constitutive expression of MC2 an d MUC3 mRNA in inflammatory bowel diseases suggests that these genes m ay be necessary for maintenance of normal epithelial cell function dur ing inflammation.