[Mucin core peptide expression in malignant and non-malignant colorectal tissues]

Three human mucin cDNAs (Muc-1, Muc-2, Muc-3) have recently been cloned and sequenced. The major portion of each mucin consists of sequences repeated in tandem along the protein. Three mucins are distinct due to differences in tandem repeat length, lack of sequence homology and different chromosomal locations of their genes. Since altered mucin glycosylation occurs in cancer resulting in exposure of core carbohydrate, we postulated that increased exposure or other alteration of core peptide structure may occur in cancerous tissues. Antibodies against Muc-1, Muc-2, Muc-3 tandem repeats were used for immunohistochemical analysis of normal, non-malignant and cancer tissues. The results indicate that in normal tissues, only Muc-2 expressed, while in cancerous tissues all three mucin core peptides were significantly accumulated, All of the three mucin core peptides increasingly expressed in adenoma, dysplasia epithelium and active ulcerative colitis (pre-malignant lesions), but not in the hyperplastic polyps, ischemic colitis and quiescent ulcerative colitis (non-malignant diseases).