Morphological change, loss of Delta psi(m) and activation of caspases uponapoptosis of colorectal adenocarcinoma induced by 5-FU

Apoptosis is clearly distinguished from necrosis, morphologically and chemi cally. Morphologically, apoptosis is characterized by a condensed nucleus a nd the disappearance of microvilli without disruption of the cytoplasm. In this report, we demonstrate that 5-fluorouracil (5-FU)-induced early apopto tic cells are characterized by (i) ultracondensed mitochondria, (ii) no cha nge in the microvilli or nucleus, (iii) a high mitochondrial transmembrane potential (Delta psi (m)), and (iv) being annexin V-negative. The early apo ptotic cells also show the active forms of caspase 8 and caspase 9. They ra pidly lose Delta psi (m) after further incubation. Therefore, we conclude t hat the ultracondensation of mitochondria precedes the loss of Delta psi (m ), and the exposure of phosphatidylserine to the outer leaflet of the cell membrane. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.