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decreased in a dose-dependent manner. After 48 and 72 h incubation with 20 mM
taurine, cell proliferations were decreased to 28.9% and 37.5%, respectively, com-
pared to control. Single treatment of cisplatin (low concentration) has little decreased
cell proliferations (11.8% at 48 h and 21.3% at 72 h). Furthermore, co-treatment of
cisplatin with taurine has more decreased cell proliferations than single treatment of
cisplatin or taurine. In co-treatment of cisplatin with taurine for 48 h and 72 h, cell
proliferations were decreased to 42.4% and 53.8% compared with the control.
Because of higher effects of 72 h than 48 h, the following experiments were per-
formed for 72 h (Fig.
19.1
).
19.3.2
Co-treatment of Cisplatin with Taurine Increases
Apoptotic Cells
Reduced cell proliferations were caused by induction of apoptosis. For investigation
of apoptotic cells, cells were imaged using DAPI as fl uorescent probes. DAPI binds
to DNA in the cell nucleus, so that chromatin agglomeration and fragmentation
occurring by apoptosis were observed by fluorescence microscopy. The results indi-
cated that single treatment of taurine or cisplatin induced apoptosis. In co-treatment
of cisplatin with taurine, the incidence of apoptosis was more increased than single
treatment of taurine or cisplatin (Fig.
19.2
).
19.3.3
The p53 Was Increased in Single and Co-treatment
of Cisplatin with Taurine
When apoptosis occurred, expression of p53 was investigated by western blotting.
Taurine or cisplatin increased p53 level in a dose-dependent manner. In co-treatment
of cisplatin with taurine, expression of p53 was increased compared to control
(Fig.
19.3
).
19.3.4
Taurine Increases Cleavage of Caspases in a Dose-
Dependent Manner
Apoptosis is mostly mediated by apoptosis-related enzymes known as caspases.
In this study, we investigated caspase-9, caspase-7, and caspase-6 by western blot-
ting. Caspase-9 was increased by single treatment of cisplatin or taurine compared
to control, but co-treatment of cisplatin with taurine does not enhance the effects. In
single treatment of taurine, caspase-7 was increased in a dose-dependent manner.
Taurine more affected the expression of caspase-7 than cisplatin, whereas caspase-7
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