3.6. Disruption of mitochondrial membrane potential (Dwm) by MPEE
Significant increases inDWm were observed for both skin cancer cell lines. Treatment with 10lg/ml of MPEE for 48 h significantly increased% cells positive for JC-1 monomers from 9% in
untreated cells to 44% on both cell lines (Fig. 6)(P< 0.05).
3.7. Effect of MPEE on the expression of cell cycle and apoptosis-related
genes
As determined by qRT-PCR, MPEE was found to inhibit proliferation of the skin cancer cells by altering the expression of the cell
cycle and apoptosis-related genes (Fig. 7). Compared with the untreated control, MPEE at 10lg/ml induced a 12.5- and 3.5-fold increase in the mRNA expression of cytochromecin A-431 (P< 0.05)
and SK-MEL-28 cells (P< 0.01), respectively (Fig. 7a and c). In A-431 cells, treatment with MPEE at 10lg/ml induced a 5.4-fold decrease in the mRNA expression of Akt1 (Fig. 7a;P< 0.01), and a 2.4-fold increase in the ratio of Bax/Bcl-2 (Fig. 7b;P< 0.05) compared
with the untreated control. However, mRNA expression of these
three genes was not significantly altered by MPEE in SK-MEL-28
cells. In SK-MEL-28 cells, a 10.6-fold increase in mRNA level of
p21
WAF1
was found after treatment with MPEE at 10lg/ml
(Fig. 7c; P< 0.05), while that of cyclin D1 remained unchanged
(Fig. 7c). No significant changes in the mRNA levels of NFjB and
IjBawere found after treatment of MPEE on A-431 or SK-MEL-28 cell lines (Fig. 7a and c).