Kinetics of the mucous cells of the rectum in patients with chronic ulcerative colitis

Cell proliferation biomarkers in the gastrointestinal tract

Measurements of epithelial cell proliferation in the mucosa of the gastrointestinal tract pointed out the existence of cell kinetic abnormalities which can be involved in the first steps of carcinogenesis. In particular, an increase in the cell proliferation rate and an abnormal distribution of proliferating cells were found both in animals exposed to carcinogens and in human subjects at high risk of gastrointestinal cancer. In some diseases which predispose to cancer (i.e., chronic atropic gastritis, hereditary gastrointestinal cancer, sporadic colorectal neoplasia, chronic ulcerative colitis) we observed an expansion of the proliferative compartment even when the mucosa was not affected by morphological abnormalities. This proliferative feature seems to be associated with the presence of defects in cell differentiation. The abnormality is well detected by the histological examination of the proliferative pattern using microautoradiography after incorporation of tritiated thymidine, or using immunohistochemistry after bromodeoxyuridine uptake. The literature, and our own results, indicate that the search for abnormalities of epithelial cell proliferation can be useful in studying the earliest mechanisms leading to gastrointestinal cancer, in detecting subjects at high cancer risk, and for pilot chemoprevention studies using these abnormalities as intermediate biomarkers of gastrointestinal cancer risk.

Proliferative defects in ulcerative colitis patients

The proliferative characteristics of epithelial cells in rectal biopsies from a group of 18 patients (ages 18-72) with ulcerative colitis spanning several months to over 20 years duration were examined, using an in vitro 3HTdR labeling technique. Although the labeling indices for patients with inflammatory bowel disease did not differ significantly from that of control (8.9 +/- 3.6 vs 7.7 +/- 3.9), the number of labeled cells/individual crypt column was higher among some crypts in ulcerative colitis patients. A normal proliferative pattern was demonstrated in crypts of 5/18 patients (27.8%) with DNA synthesis confined to the lower two-thirds of the crypt and the lower third the major zone of proliferation. Thirteen patients (72.2%) showed extension of the proliferative compartment to the surface of the glands, while retaining the lower third of the gland as the predominant proliferative zone (Stage I abnormality). Of these 13, seven had an additional abnormality, namely, a shift of the major zone of proliferation to the middle third of the crypt (Stage II abnormality), a pattern first reported in the colorectal mucosa of patients with a history of colon cancer. Precancerous lesions, including incompletely differentiated epithelium and lateral crypt budding, were recognized in all of these cases, suggesting that the Stage II abnormality is a proliferative parameter forecasting neoplastic transformation.