Objective    To explore the onset and mechanisms of apoptosis in 786-0 cells treated with As

2

O

3

.     Methods    The onset of apoptosis in 786-0 cells was investigated by FCM and TUNEL

and the changes of apoptosis related genes

such as p53

bcl-2

c-myc

c-fos

NF-κB p65

and NF-κB DNA binding activity were analyzed by ICC

RT-PCR

ISH

Western blot and EMSA.     Results    The characteristic apoptotic morphological changes were evaluated after treated with ≥2 μmol/L As

2

O

3

and FCM re

vealed that 2 μmol/L As

2

O

3

could induce a sub-G1 peak in 786-0 cells after 24-hour treatment. The expression of p53 gene was up-regulated (P0.05)

while bcl-2

c-myc

c-fos

and NF-κB p65 were down-regulated (P0.05). NF-κB DNA binding activity was significantly inhibited (P0.01).     Conclusion    As

2

O

3

can obviously induce the apoptosis of 786-0. Its mechanisms are supposed to down-regulate the expression of bcl-2

c-myc and c-fos genes

and up-regulate the expression of p53 gene through inhibiting NF-κB signaling.