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5-Azacytidine (5Az) induces apoptosis in PC12 cells: a model for 5Az-induced apoptosis in developing neuronal cells
M.M. Hossain1, H. Nakayama1, A. Takashima2, N. Goto3 and K. Doi1
1Department of Veterinary Pathology, Faculty of Agriculture, The University of Tokyo, Bunkyo-kyu, 2Mitsubishi Kagaku Institute of Life Sciences, Tokyo and 3Shin Nippon Medical Laboratories, Tokyo, Japan
Offprint requests to: Dr. Hiroyuki Nakayama, Department of Veterinary Pathology, Faculty of Agriculture, the University of Tokyo, 1-1-1 Yayoi,
Bunkyo-ku, Tokyo 113, Japan
Summary. Our previous in vivo and in vitro studies
showed that 5-azacytidine (5Az), a cytidine analog,
induced apoptosis in developing neuronal cells in mice.
To develop a system in which the precise molecular
mechanism of 5Az-induced apoptosis in developing
neuronal cells could be elucidated, we carried out the
present study with PC12 cells. These cells are derived
from a rat pheochromocytoma and extrude neurites in
response to nerve growth factor (NGF). Light
microscopy showed dose-dependent pyknotic and
karyorrhectic changes in undifferentiated PC12 cells.
Although they were less sensitive to 5Az, NGF-treated
differentiated cells showed the same changes. Analysis
by the TUNEL method (an in situ method for the
detection of apoptosis) showed positive signals in the
pyknotic and fragmented nuclei of these cells.
Transmission electron microscopy revealed margination,
segmentation, and condensation of nuclear chromatin,
cell body shrinkage, and cytoplasmic vacuolization.
Scanning electron microscopy demonstrated bleb
formation on the cell surface. These pathomorphological
changes are typical of apoptosis. 5Az seemed to affect
cells that were in the proliferative stage; when the cells
were terminally differentiated, their sensitivity to 5Az
appeared to decline . PC12 cells could be used as a
pathomorphological and biochemical model for studies
of 5Az-induced neuronal cell apoptosis at the molecular
and genetic level. Histol Histopathol 12, 439-445 (1997)
Key words: Apoptosis, 5-Azacytidine, Central nervous
system (CNS), PC12 cells
DOI: 10.14670/HH-12.439
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