During Chinese hamster ovary (CHO) cell culture for foreign protein production, cells are subjected to programmed cell death (PCD). A rapid death at the end of batch culture is accelerated by nutrient starvation. In this study, type II PCD, autophagy, as well as type I PCD, apoptosis, was found to take place in two antibody-producing CHO cell lines, Ab1 and Ab2, toward the end of batch culture when glucose and glutamine were limiting. The evidence of autophagy was observed from the accumulation of a common autophagic marker, a 16 kDa form of LC3-II during batch culture. Moreover, a significant percentage of the total cells (80% of Ab1 cells and 86% of Ab2 cells) showed autophagic vacuoles containing cytoplasmic material by transmission electron microscopy. An increased level of PARP cleavage and chromosomal DNA fragmentation supported that starvation-induced apoptosis also occurred simultaneously with autophagy.
(c) 2007 Wiley Periodicals, Inc.