Rintaro Narisawa

Post-translational stabilization of beta-catenin through mutation of the adenomatous polyposis coli (APC) gene has been proposed as an early step in colorectal carcinogenesis. Beta-catenin may translocate from the cytoplasm to the nucleus, where it might serve as a transcriptional factor to stimulate tumour formation. We investigated intracellular localization of beta-catenin in sporadic colorectal adenomas and cancers as well as familial adenomatous polyposis (FAP). Nuclear over-expression of beta-catenin was observed in 35% (7/20) of intramucosal cancers and 42% (23/55) of invasive cancers but was not seen in any adenomas from sporadic or FAP cases. Cytoplasmic beta-catenin in adenomas was significantly higher than that of normal mucosa in both sporadic and FAP cases. The cytoplasmic intensity index of cancers was significantly higher than that of sporadic adenomas, but the index was not correlated with nuclear expression in cancers. These findings suggest that nuclear translocation of beta-catenin is involved in development of intramucosal cancer rather than adenoma, independent of APC mutations. Cytoplasmic accumulation of beta-catenin may occur in adenomas, but it remains to be determined whether this is a cause or a consequence of colorectal cancer.

Administration of dextran sulphate sodium to animals induces acute colitis characterized by infiltration of large numbers of neutrophils into the colonic mucosa, which histologically resembles human active ulcerative colitis. It has been reported that neutrophils and the reactive oxygen metabolites produced by them are involved in the progress of ulcerative colitis. This study was intended to clarify their roles by using this animal model. First, possible sources and species of reactive oxygen metabolites were determined using luminol-dependent chemiluminescence with addition of enzyme inhibitors and reactive oxygen metabolite scavengers. Next, to examine whether neutrophils and hypochlorous acid derived from them contribute to tissue injury, we administered RP-3, a monoclonal antibody capable of selectively depleting neutrophils, and taurine, a hypochlorous acid scavenger, to rats treated with dextran sulphate sodium. Addition of azide, taurine, catalase, superoxide dismutase and dimethyl sulphoxide into colonic mucosal scrapings significantly inhibited chemiluminescence production, but allopurinol and indomethacin had no effects. These results suggest that excessive hypochlorous acid, hydrogen peroxide, superoxide anion and hydroxyl radical are generated by the inflamed colonic mucosa. Intraperitoneal injections of RP-3 significantly suppressed bleeding, tissue myeloperoxidase activity, chemiluminescence production and erosion formation. On the other hand, administration of taurine tended to inhibit bleeding and erosion formation to some extent, although it could not significantly suppress them. These data suggest that neutrophils play an important role in the development of this colitis and that hypochlorous acid might be one of the causes of tissue injury induced by neutrophils.

BACKGROUND: The major duodenal papilla is a common site of extracolonic adenoma in patients with familial adenomatosis coli (FAC). However, there have been no reports which have systematically discussed histologic change in atypia of ampullary adenomas with time by their location in the papilla. METHODS AND RESULTS: The major duodenal papillae of 23 patients with FAC were followed endoscopically and histologically for an average of 7.7 years (range, 1 year to 14 years 7 months). Tubular adenomas were detected histologically in 17 of the 23 patients at the first (14) or following examinations (3). They occurred in the orifice and/or ampulla in 11 patients and in the surface of the papilla in 8 patients. Three of the 11 orifice and/or ampulla adenomas contained moderate to severe atypia. There was no histologic change in atypia or malignant transformation during the follow-up period. CONCLUSIONS: In the patients with FAC, the major duodenal papilla had adenoma, i.e., precancerous lesion, at a high incidence (74%), and it is reported that the ampulla of the papilla tended to have extracolonic carcinoma. Therefore, it is necessary to follow duodenal papillae of patients with FAC carefully and take biopsy specimens repeatedly from various sites, especially from the orifice or ampulla even if the papilla seems to be normal.