Sulforaphane synergizes with cisplatin in suppressing cancer cell proliferation and promoting apoptosis of ovarian cancer cells. (A) Synergism between sulforaphane and cisplatin. A2780 cells were treated with sulforaphane and cisplatin at the indicated concentrations. After 24 h, WST-1 reagent was administrated to the culture medium and then incubated for 1 h. The WST-1 activities were determined at 440 nm. (B) Colony formation assay. Subconfluent A2780 cells were seeded in plates and treated with sulforaphane and cisplatin at the indicated concentrations. After 48 h, the cancer cells were then fixed and stained with crystal violet for the colony formation assay. (C) Colony-forming ability of ovarian cancer cells following sulforaphane and cisplatin treatment was quantified for optical absorbance. (D) Western blot assays with (E) quantification were performed to determine protein levels of Bcl-2, Caspase-3, P53, and Cyclin-D1 in A2780 cells treated with or without sulforaphane and cisplatin. The values are presented as the mean ± standard deviation (n=8-10) of the samples. +P<0.05, ++P<0.01 and +++P<0.001, vs. 0 μM group. SFN, sulforaphane; Cis, cisplatin; Bcl-2, B-cell lymphoma 2.