Reversible cell cycle arrest with concomitant p21/WAF1 overexpression and mitochondrial destruction by nitric oxide.
When human hepatocellular carcinoma Hep-G2 cells were treated with the NO-generating compounds, S-nitroso-N-acetyl-DL-penicillamine(SNAP) or (+/-)-(E)-4-ethyl-2-(E)-hydroxyimino]-5-nitroso-3-hexenamide, cells stopped growing. Most cells were found to be in either G1 or G2/M phase and the dye-exclusion test revealed that the cells were alive. Electron microscopic examination confirmed the integrity of cells and nuclei. Nuclear staining with the DNA-binding dye H33258 revealed that cells did not undergo apoptosis although dramatic changes in mitochondrial morphology were noticed within 6 hr of treatment with SNAP by electron microscopy. Western and northern blot analysesrevealed that cells overexpressed p21/WAF1. The growth arrest was released by withdrawal of the NO-generating compound and cells started to divide within 24 hr after withdrawal of the compounds.
Esumi
H
H
Investigative Treatment Division, National Cancer Center Research Institute, Chiba, Japan.
Chin
K
K
Kurashima
Y
Y
Hasegawa
F
F
Ogura
T
T
Yoneda
M
M
Ozawa
T
T