5-Fluorouracil-induced intestinal toxicity: what determines the severity of damage to murine intestinal crypt epithelia?

To elucidate the relationship between 5-fluorouracil (5-FU) distribution and 5-FU-induced apoptosis and/or cell cycle arrest, microautoradiography was applied to murine intestinal crypts exposed to [C-14] 5-FU by intravenous infusion. The histologic location of apoptotic cells in the crypt did not correlate to that of 5-FU. The temporal profiles of apoptotic and/or mitotic indexes corresponded to those of orally administered 5-FU in a previous study. Two cell cycle-related proteins, p21(WAF/Cip1) and bax, were also investigated in the present study. With time, p21(WAF/Cip1)-positive nuclei apparently migrated up the crypt. Bax-positive cytoplasm was observed throughout the crypt epithelial cells, accompanied by the occurrence of apoptosis, and remained until 48 h when the control level recovered. The findings demonstrate that 5-FU mainly exerts an apoptotic effect and/or cell cycle arrest by systemic exposure, and p21 and bax expression determine an individual cell's fate. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.