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Changes in mucin gene expression may be a useful marker in surveillance for colorectal cancer in patients with a pelvic ileoanal reservoir (IAR), a molecular study has suggested. Biopsy specimens from IARs showed a mucin pattern similar to that in ulcerative colitis (UC): expression of membrane associated mucins MUC1 AND MUC3 was less than in ileal control specimens whereas expression of mRNA transcripts was unchanged. Conversely, no mRNA transcripts were detected for mucins MUC5AC, MUC5B, AND MUC6 associated with colorectal cancer, though MUC5AC protein occurred in five IARs and MUC6 protein in two. In one and two of these cases, respectively, this was in an ulcer associated cell lineage. None of the specimens showed histological evidence of cancer.
Specimens were taken from 40 patients undergoing yearly surveillance after an IAR constructed 1–10 years before for UC or familial adenomatous polyposis (FAP). These were taken at random from the back wall of the reservoir. Control ileal and colonic specimens were taken from other patients with neither UC nor FAP. Messenger RNA transcripts were detected by in situ hybridisation of thin sections with radiolabelled oligonucleotide probes. Mucins were detected by staining with antibody to peptide sequences of core protein.
Mucins form part of the mucosal defence of the gut. Their pattern changes in colorectal cancer, when MUC5AC and MUC6 are newly expressed. IARs show no evidence of cancerous change according to mucin glycosylation, but pattern of expression has not been looked at before. The risk of cancer after an IAR, although low, is still a concern.