Figure 3.

The effects of paclitaxel (PTX) combined with mitogen‐activated protein kinase kinase (MEK) and phosphatidylinositol 3′‐kinase (PI3K) inhibitors on ovarian cancer cells. (a) Five ovarian cancer cell lines were treated with varying concentrations of PTX along with phosphate‐buffered saline, or 25 µM PD98059 (PD) and/or 5 µM LY294002 (LY) for 72 h compared with the control. Cell‐growth inhibition was determined using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐dyphenyltetrazolium bromide assay. Cell proliferation was significantly suppressed by PTX combined with MEK and PI3K inhibitors compared with other treatment conditions (P < 0.01). Points represent mean ± SD from six dishes. (b) Cells were treated with 100 nM PTX (the KF, SK‐OV‐3, and SHIN‐3 cell lines) or 300 nM PTX (the KOC‐2S and KFTx cell lines) in the presence or absence of 50 µM PD and/or 10 µM LY for 36 h, then stained with annexin V–fluorescein isothiocyanate. The number of apoptotic cells increased significantly after treating with PTX combined with both the MEK and PI3K inhibitors, compared with the other treatments (P < 0.05). The points represent mean ± SD from three dishes. (Inset) DNA fragmentation was also observed 48 h after treatment with a combination of PTX with both PD and LY in all cell lines. Lane 1, no treatment; lane 2, LY+PD+PTX; and lane 3, 100‐bp DNA ladder as standard. The results shown represent duplicate experiments. (c) The combination effects of PD and LY were synergistic with those of PTX in ovarian cancer cells. PTX was combined with PD and LY at a fixed ratio that spanned the individual IC₅₀ of each drug. Data were analyzed using the method of Chou and Talalay.^{( 16 )} The results shown represent duplicate experiments. p, phosphorylated.