353.3.2 Results and Analysis
3.3.2.1 In Vitro Evaluation of ASC on Tumor Cell Proliferation
The optimal dosages of all components should be lower than their IC 50 , i.e.,
70 μM for ART, 20 μM for DM, 210 μM for MA, and 700 μM for AT. According
to this principle, we designed ASC as 50 μM ART, 5 μM DM, 10 μM MA, and
10 μM AT. In the present study, we compared the antitumor effects of ASC with
ART through in vitro evaluation tests.
After incubation of HepG 2 cells with ART or ASC for 48 h, it was observed
that cell proliferation is extraordinarily suppressed. From the absorbance
at 490 nm (A 490 ) of 1.55 ± 0.10 for the control, 0.83 ± 0.08 for ART, and
0.50 ± 0.09 for ASC, the growth inhibition rates were calculated to 46.76 % for
ART and 67.26 % for ASC. These results indicated that ART and ASC suppress
the in vitro propagation of tumor cells, but ASC allows a higher inhibition rate
than ART alone.
3.3.2.2 In Vivo Evaluation of ASC on Graft Tumor Growth
Because of their capacity to exhaust GSH and inhibit antioxidant enzymes, pro-
oxidants in ASC can attenuate antioxidation and enhance oxidative stress, thereby
inducing apoptosis in tumor cells. For evaluating ASC’s in vivo antitumor effects,
we measured the tumor weight and tumor volume before and after treatment in
tumor-bearing nude mice, from which the sensitizing potential of each pro-oxidant
to ART for killing tumors should be clarified.
For in vivo evaluations, the optimal dosage for each drug was chosen by referring
to 50 % of corresponding lethal dosages (LD 50 ), usually equivalent to 1/10–1/20
LD 50. The treatment regimens were divided into a short-term treatment and a long-
term treatment. In the latter group, ASC was administered by either subcutaneous
injections or intratumor injections. As comparison, FLU was included in the in vivo
tests. The results were shown in Table 3.2 and Fig. 3.1.
From above results regarding the tumor weight and tumor volume, it is clear
that the pro-oxidants in ASC can certainly sensitize ART to achieve the more
effective results of antitumor activity.
3.3.2.3 Mechanisms of Chemosensitizer-Enhanced Antitumor Activity
of ART
Upon treatment of HepG 2 by ASC or ART alone for 24–48 h, we noticed that the
measured GSH content, GSH-POX activity, and CAT activity are dramatically
declined (Fig. 3.2).
3.3 Pro-oxidant Agents Synergize ART in Killing Tumor Cells