fluorescent dye, DiOC6. As shown in Fig. 6, a drop in the
mitochondrial membrane potential was observed. The data show
that changes in the membrane potential were induced in treated
95-D cells during 4 and 8 h treatments. A significant decrease of
Δψm was detected in cells treated with 50 μg/ml GA-T for 4 and
8 h. Compared to control, the decrease in the mean fluorescence
density was about 10% and 16.7%, respectively. The results
illuminate that GA-T could induce Δψm dissipation in a timedependent
manner. A drop in the mitochondrial membrane
potential is usually accompanied by release of cyt-c into the
cytosol. As shown in Fig. 7, cyt-c levels in the cytosol of GA-T
treated cells showed a rapid increase. A one-fold increase was
seen within 4 h. At 8 h, about 3-fold increase in the cyt-c level
was observed. The data indicate that GA-T increased the release
of cyt-c to cytosol in treated tumor cells.
GA-T induces activation of caspase-3 but not caspase-8
In general, induced apoptosis is often associated with activity
of a series of caspases, such as caspase-3 and caspase-8. In this
work, the activity of caspase-3 was detected in 95-D cells treated
by GA-T. The data are shown in Fig. 8A. GA-T noticeably
stimulated the activity of caspase-3 in tumor cells in a dosedependent
manner. The activity of caspase-3 increases 2- and 3-
fold respectively at 4 and 8 h under the drug concentration of