Figure 6.

Notch-1 siRNA promoted, but Notch-1 cDNA reduced, As₂O₃-induced cell growth inhibition and apoptosis in SKBR-3 breast cancer cells (A–B). Left panel, down-regulation of Notch-1 by siRNA significantly inhibited SKBR-3 breast cancer cell growth. 8 μM As₂O₃ plus Notch-1 siRNA inhibited cell growth to a greater degree compared to As₂O₃ alone. Right panel, down-regulation of Notch-1 expression significantly increased apoptosis induced by As₂O₃. Notch-1 siRNA transfected cells were significantly more sensitive to spontaneous and As₂O₃-induced apoptosis (C–D). Over-expression of Notch-1 by cDNA transfection rescued As₂O₃-induced cell growth and abrogated As₂O₃-induced apoptosis to a certain degree. * p < 0.05, compared with the control; ** p < 0.05, compared with As₂O₃ treatment alone and Notch-1 siRNA transfection alone. # p <0.05, compared with As₂O₃ treatment alone and Notch-1 cDNA transfection alone.