Mcl-1 plays critical roles in regulating the sensitivity of melanoma cells to apoptosis induced by EGb761.

<p>(A) Knockdown of Mcl-1by siRNA decreases the levels of Mcl-1expression. Mel-RM and Mel-AT cells were transfected with scramble SiRNA or Mcl-1siRNA. Whole cell lysates were then subjected to Western blot analysis.(B) Inhibition of Mcl-1 by siRNA induces apoptosis of melanoma and sensitizes melanoma cells to EGb761-induced apoptosis. Mel-RM and Mel-AT cells were transfected with scramble or Mcl-1siRNA. 24hours later, the cells were switched into normal culture medium for a further 48 h followed by treatment with 5% ethanol or EGb761. After another 24 hours, the cells were subjected to measurement of sub-G1content by the propidiumiodide method using flow cytometry. The data shown are the mean ± SEM of three individual experiments. * Present p<0.05 vs control.(C) Knockdown Mcl-1 can affect Bax and Bak activation status in Mel-RM cells. SiRNA inhibition of Mcl-1 resulted in a marked increase in the levels of conformational changed Bax and Bak, which detected by flow cytometry. The open and filled histograms were generated from control (5% ethanol) (C) and EGb761-treated (E) cells respectively. The numbers represent MFIs. The data shown are representative of three individual experiments.(D) Expression of Mcl-1 in a panel of melanoma cell lines after treatment with EGb761 or control (5% ethanol) for 24 hours. Whole cell lysates from melanoma cells were subjected to Western blot analysis. The data shown are representative of three individual experiments.